TI Flashcards

Question

What are the two types of microcytic anaemia?

Answer 1

Magaloblastic: Low reticulocyte count: - Vitamin B12/folic acid deficiency - Drug-related - (Interference with B12/FA metabolism) Nonmegaloblastic: - alcoholism ++ - hypothyroidism - liver disease - myelodysplastic syndromes - reticulocytosis (haemolysis) Vitamin B12 = cobalamin and folic acid are both are important for the final maturation of RBC and for the synthesis of DNA. We also need both for thymidine triphosphate synthesis.

Answer 2

folate is necessary for DNA synthesis: adenosine, guanine and thymidine synthesis

Answer 3

Folate comes from most foods with 60-90% lost in cooking. It is absorbed in the jejunum and the body has enough stores usually for 3-5 months INCREASED DEMAND: pregnancy/breastfeeding, infancy and growth spurt, haemolysis and rapid cell turnover e.g. SCD, disseminated cancer, urinary losses e.g. heart failure DECREASED INTAKE: poor diet elderly, chronic alcohol intake DECREASED ABSORPTION: medication, coeliac, jejunal resection, tropical sprue

Answer 4

This is an essential co-factor for methylation in DNA and cell metabolism. There is intracellular conversion to 2 active coenzymes necessary for the homeostasis of methylmalonic acid (MMA) and homocysteine. • Foods containing vitamin B12: animal sources – fish, meat, dairy • UK intake recommendations are 1.5mcg/day • EU: 1mcg/day and USA: 2.4mcg/day • The average western intake is 5-30mcg/day • Body (liver) storage: 1-5mg so many years for deficiency. • Absorption of vitamin B12 in the terminal ileum requires the presence of intrinsic factor. IF is made in parietal cells in the stomach. Transcobalamin II and transcobalamin I transport vitamin B12 to tissues

Answer 5

- haemolysis - HIV - pregnancy - growth spurts

Answer 6

Brain: cognition, depression, psychosis Neurology: myelopathy, sensory changes, ataxia, spasticity (SACDC) Iron deficiency is the most common nutritional deficiency as well as the most common cause of anaemia throughout the world and a common cause of referral. Premenopausal women with excessive menstrual losses are particularly at risk of developing iron deficiency anaemia (IDA). Infertility Cardiac cardiomyopathy Tongue: glossitis, taste impairment Blood: pancytopenia

Answer 7

* Autoimmune disorder * Lack of IF * Lack of B12 absorption * Gastric parietal cell antibodies * IF antibodies

Answer 8

* Treat the underlying cuase * Iron: diet, oral, parenteral iron supplementation, stopping the bleeding * Folic acid: oral supplements * B12: Oral vs intramuscular treatment

Answer 9

- Blood cell production - Bone marrow - Long bones - Maturation occurs in bone marrow - Mature cells within peripheral blood The purple tubes have EDTA in to stop the blood from clotting. As it doesn’t clot, if the blood is left for long enough it will segment out into its components

Answer 10

``` Red blood cell results • Hb: concentration of Haemoglobin • Hct: percentage of blood volume as RBC • MCV: average size of RBC • MCH (mean cell Hb): Average haemoglobin content of RBC • RDW (red cell derivation width): range of deviation around RBC size • Reticulocyte count • Blood film ``` Hct: haematocrit (% of blood volume that is RBC) – usually around 50-52% Not just RBC results… • WHITE BLOOD CELL RESULTS: total WBC and differential neutrophils, lymphocytes, monocytes, basophils, eosinophils • PLATELET RESULTS: platelet count and size • OTHERS: warning flags

Answer 11

Confirming numbers Morphology – are the cells ‘normal’ Are there cells present that shouldn’t be? ``` o PURPLE: clotting o PINK: EDTA cross matching in blood transfusions o BLACK: ESR o RUST: clots biochemistry o GREEN: lithium pagrin ``` Tube colour does matter!! In a lab, around 1600 FBC samples are processed every day! Peroxide stain picks up myeloperoxidase in neutrophils

Answer 12

* These are seen in myelofibrosis or bone marrow infiltration with malignant disease * This suggests there is something else sitting inside the bone marrow * This wouldn’t be picked up in a numbers count

Answer 13

This is a protective process evolved in order to maintain a stable physiology. It forms a scaffold like structure so that the body can go on to heal Haemostasis does more than just preventing blood loss. It also works in the context of someone who has an infection Life preserving process designed to maintain blood flow: - Respond to tissue injury - Curtail blood loss - Restore vascular integrity and promote healing - Limit infection

Answer 14

Coagulation is being activated by infection and blocking off the bacteria from getting to more vital places in the body. For example, the young child’s hand has become infarcted in trying to prevent the infection from getting to the liver or heart for example, and losing the hand as a result of this may not be as bad as the otherwise possible consequences. Our biggest killer now is us (war, violence), rather than infection

Answer 15

- endothelium - platelets - coagulation - fibrinolysis

Answer 16

- Fibrin mesh - Platelets - Red blood cells Platelets are the main features of a clot and they are very complex. Fibrin makes the mesh which is the proteins that come out of solution and is the final end point to strengthen the clot. Without this, people would bleed

Answer 17

When you cut yourself, the first thing that happens is that you lose blood. Vasoconstriction occurs which reduces the size of the cut and therefore the amount of blood lost. There is lots of smooth muscle around the blood vessels to allow for this. Next we get a platelet plug. The platelets recognise the damage to the endothelium and stick there to limit blood loss. This isn’t a very strong plug however, and it would only work for a little while. Fibrin comes out to strengthen this and maintain the clot by forming a mesh

Answer 18

Primary Haemostasis: - Vasoconstriction (immediate) - Platelet adhesion (within seconds) - Platelet aggregation and contraction (within minutes) Secondary Haemostasis: - Activation of coagulation factors (within seconds) - Formation of fibrin (within minutes) Fibrinolysis: - Activation of fibrinolysis (within minutes) - Lysis of the plug (within hours) There are several different aspects to haemostasis. There is a fibrinolytic mechanism that occurs almost straight away in order to modify the clot and make sure it only stays at the site of injury

Answer 19

In the lumen there are lots of components that are very important for haemostasis; platelets, VWF etc. VWF is very important and people without it bleed. It is the anchor for the platelets to adhere to at the site of injury. In the subendothelium there are the initiators for when you injur yourself; collagen and tissue factor

Answer 20

In a damaged vessel there are two crucial molecules exposed, forget tissue factor. Primary haemostasis involves collage. It interacts with VWF in the blood and then VWF unravels and acts as the anchor for platelets to adhere to that damaged area. The platelets adhering transform from small and round into star shaped cells, releasing their components that they are carrying, which makes more platelets and VWF coming along. This provides a nice phospholipid surface for the fibrin

Answer 21

VWF in the endothelium us released when you damage the surrounding area. It is vital for platelets to adhere. VWF unravels when it gets released, allowing the platelets to identify there is a problem and stick to it. You then form a platelet clot

Answer 22

Platelet aggregation prevents excessive blood loss at the site of injury

Answer 23

The things inside are exposed to the blood. Tissue factor and collagen are the important ones. Collagen causes the platelets to adhere and release substances to cause more platelets to migrate to the site. A platelet plug then forms and we get primary haemostasis

Answer 24

¥ When a vessel wall is damaged, various signalling molecules are expressed / exposed, including tissue factor and collagen ¥ The TF leads to the production of a small local amount of thrombin, which is the initiation step of the coagulation process ¥ The exposed signalling molecules attract circulating platelets, which attach themselves to the exposed sub-endothelial tissue (mechanism to be discussed later): this is adhesion ¥ These platelets become activated – principally through the presence of the thrombin – and release further attractant chemicals, which attract more platelets: this is secretion ¥ These new platelets bind to the adhered platelets (mechanism to be discussed later) and themselves become activated: this is aggregation ¥ Through the conformational changes inherent in activation, the loose platelet plug contracts to form a dense, adherent plug: this is contraction ¥ Together these steps comprise primary haemostasis, which may well be sufficient to achieve haemostasis if the injury is relatively minor ¥ The activated platelets also present a substantial area of negatively-charged phospholipid membrane at the site of the injury, upon which the subsequent processes of coagulation (secondary haemostasis) can occur, if needed

Answer 25

The fibrin mesh binds and stabilises the platelet plug and other cells. In coagulation fibrin forms, there are lots of clotting factors that circulate in the plasma. Most of them are produced in the liver and are complex. In the last 20-30 years we have learnt the crystalline structures of compositions of them

Answer 26

There are 13 coagulation factors and we don’t really need to learn them all. A haematologist will refer to them as their numbers. We need so many because the more you have, the more easily you can achieve regulation – ie we don’t need to turn everything off or everything on. This about having lots of light switches, you would be able to alter the light more specifically

Answer 27

Blood has an intrinsic ability to clot. It can clot without any obvious provoking factors. We call this contact activation – surface contact. The easiest way to think of it is if you cut yourself and go and clean it and wrap it up in the process made a mess of blood on bench and the blood on the bench has clotted and this is the intrinsic ability – there was no tissue factor and it clots because of a foreign surface. Factor 12 and some others can recognise a foreign, non physiological surface. These in turn can cause a clot to occur. Factor 12 activates 11 activates 9 joins up with common area does 10 then thrombin and then fibrin

Answer 28

FVII deficiency causes bleeding: without factors we get bleeding. For example, without factor 7 we have a bleeding disorder and cant drive forward coagulation.

Answer 29

FXII deficiency is not associated with bleeding: without 12 there is no bleeding problem. This shows that the role it plays physiologically in forming clots isn’t quite the same

Answer 30

Each reaction requires: - Ca2+ - Phospholipid - ± specific co-factors In reality, these two limbs of the cascade, intrinsic and extrinsic, have a much more complex interaction

Answer 31

- TF is outside the lumen - Formation of TF-FVIIa complex - Recruitment of FX and formation of thrombin When there is bleeding from the blood vessel the tissue factor is not usually exposed to the blood, but damage leads to 7a coming into contact with tissue factor. This leads to production of prothrombin into thrombin, and then into fibrin

Answer 32

¥ Initiation of coagulation occurs when sub-endothelial tissue is exposed to the circulation at a site of injury. These tissues express tissue factor at their surface, which binds to endogenous activated FVII ¥ This complex binds small amounts of FX and FV to the exposed endothelial surface, which produce small quantities of thrombin ¥ The thrombin activates platelets that are attracted to the site by the process, as well as other plasma-borne clotting factors ¥ The activated factors (among them FVIII and FIX) enable the binding of activated FX and FV to the surface of platelets whose activation has produce conformational changes in their surface membranes to expose the ‘reaction sites’ necessary for continuation of the process ¥ This leads to the ‘thrombin burst’ that is necessary for the large-scale production of fibrin and so the development of an effective clot ¥ These three stages are called the initiation, amplification and propagation phases of coagulation ¥ Secondary haemostasis this time ¥ Tissue factor exposed to circulating blood ¥ Forms complies with factor seven ¥ Make a little bit of thrombin ¥ Very imprint regulator ¥ Need to make a lot ¥ Seven a cant do it alone ¥ Got to activate lots of other factors to do this ¥ Then make a huge amount of thrombin – thrombin burst and then get fibrin ¥ Thee is an initiator, form a small amount and then need to make more, amplification, the fed elopement of more and more sactivzted substances to PROPAGATE and produce a huge amount

Answer 33

The process of clot dissolution: Main function - Clot limiting mechanism - Repair and healing mechanism Series of tightly regulated enzymatic steps - Feedback potentiation and inhibition

Answer 34

- Plasminogen - Tissue plasminogen activator (t-PA) and urokinase (u-PA) - Plasminogen activator inhibitor -1 and -2 - Alpha2-plasmin inhibitor

Answer 35

First component of haemostasis and the process of removing the clot. If a clot formed and never went away you couldn't replace it with normal tissue. Fibrinolysis is also important for limiting where the clot forms. It involves a lot of different steps. The main players are plasminogen, TPA which activated plasminogen, and things that turn it off. The precursor wants to chew it up and is activated by TPA. It becomes active and will remove the clot. We can measure D-dimers in the lab to see if someone is going through a lot of the process. If they are then they may have a clot. This proves that it starts the moment that you are forming a clot. If someone gets a clot it would be good if we could make this process a bit stronger. We can do this using TPA and similar substances to form plasminogen to be activated into plasminogen so it can chew up the clot

Answer 36

- Atrophic changes - Hyperpigmentation - Ulceration - Infection This can happen if you don’t get a DVT. There is damage to the blood vessels and they can become secondarily infected

Answer 37

Normal haemostasis: a state of equilibrium All the processes work in a fine balance. Blood is in a state of equilibrium between the processes The imbalance can go the other way and we get bleeding. This would happen if you don’t have enough platelets or clotting factors.

Answer 38

Easy bruising: ecchymosis This occurs in virtually all bleeding disorders and often in normal. If mild it may just result in easy bruising and heavy periods, or could be much more significant bleeding

Answer 39

There are different aspects for evaluating someone's haemostasis. A FBC is interested in platelet number. It is not very specific but can get some degree of suspicion. Fundamental tests are the coagulation tests. These aim to activate and produce fibrin. We can also do very specialised tests. We can look at if they have VWF which is the most common bleeding disorder. Global tests aren't in routine diagnostic use but more at research level need standardising

Answer 40

Incubate plasma with reagents necessary for coagulation - Phospholipid, co-factors - Trigger or activator - Calcium Measure time taken to form fibrin clot. We need to take blood from the patient and not allow it to clot until we get to the lab. We want to isolate the coagulation factors from the sample by administering triggering factors

Answer 41

rothrombin time is one of the coagulation screen tests. It is trying to look at extrinsic path and see how long it takes to occur. 7 tf to fibrin. This is called the prothrombin time or PT. PT takes from 9-13 seconds and each lab has a normal range. If someone is lacking one of the factors it will take longer so might have an abnormal PT

Answer 42

Activated partial thromboplastin time. APTT is measuring the intrinsic path. We have to add something to activate factor 12. It is a foreign substance and we used to add things like sand and then glass beads. Now we add agents that we know have the right ionic charge. APTT is the slower way to make a clot, taking 32-45 seconds. If prolonged then we must wonder what is missing. We know know what though, because this is only a screening test

Answer 43

The third assay is thrombin time. This is trying to mimic the last reaction. We wan to make a clot so we add thrombin and make sure that the end point is right

Answer 44

* Accuracy of haemostasis laboratory tests depends on the quality of the specimen submitted. * Blood is anticoagulated with 3.2% (0.109M) sodium citrate * Most tubes contain 0.3mL anticoagulant and require 2.7mLs of blood * Under filling the tube yields grossly inaccurate results We use citrates in the blood. Blood is collected in a tube containing citrate. The proportions have to be right, not too little or too much compared to the volume of blood. If the tube is only half filled for example, it cant be measured – it has to be completely full to have the right proportions

Answer 45

Problems with blue-top tube - Partial fill tubes - Vacuum leak and citrate evaporation Problems with phlebotomy - Heparin contamination - Wrong label - Slow fill - Underfill - Vigorous shaking - Difficult venipuncture Biological effects - Hct >55 or

Answer 46

We have go the plasma we can do a manual clotting test/manual APTT. When the things are added and it is kept at 37*C we just see how long it takes to clot whilst tilting 3 times every 5 seconds

Answer 47

This machine has reduced human error in seeing the end point and it is much easier to measure

Answer 48

* Clotting factor NR 50-150 IU/dL * APTT normal (24-34s) if factor level within range * 50:50 mix 32s/28s If we have an abnormal clotting factor test and it takes a lot longer than it should it is usually due to a factor deficiency. We can mix their plasma with control plasma from healthy volunteers and this should give you a normal time. If its normal then we expect that their clotting factors are abnormal. If we mix them together, in theory we are replacing all the clotting factors from the patient with something right. If they are deficient and we mix it with normal it should replace the deficiency. We measure that, and whilst we might only get 50% of one of the clotting factors, it should be enough to correct the time. If it does correct it, then the patient was deficient in something. Correction of a clotting test by mixing will investigate whether they are deficient in something

Answer 49

* Antibody in excess * Inhibits added factor * 50:50 mix 75s/30s This wont always correct it. When mixed there may still be a long APTT. This would show the patient to have antibodies so while the clotting factors have been replaced, there are still antibodies which will now interact with the normal plasma that you have added, and so we will still get a low factor as the antibodies may inhibit normal function. Something is interfering with the coagulation

Answer 50

* Mix patient and normal plasma in equal volumes (50:50 mix) * Repeat abnormal coagulation test * Test normalizes – factor deficiencies * Test remains abnormal – inhibitor (usually antibody)

Answer 51

D-dimer testing • A measure of the D-dimer, a fibrin degradation product • Found elevated in the situation of enhanced fibrinolysis (thrombosis, DIC) • Not specific for thrombosis also elevated as an acute phase reactant • A negative result is useful if clinical suspicion of VTE is low The D-dimer is a breakdown product of fibrin. It can be broken down into D-dimer form when it undergoes fibrinolysis. Someone who clots a lot will have a lot of D-dimer and this can be useful if we suspect DVT. If there is no raised D-dimer then it is likely that we are heading towards the wrong diagnosis

Answer 52

This is low technology which was used until the 1940s. It took a long time to count and was cumbersome, taking easily more than five minutes to do a single blood count. It use, you put a drop into the counting chamber with a fine grid allowing counting under the microscope once the drop has been allowed to spread

Answer 53

This is how the blood count is done now – the blood goes in, and a result comes out. This new technology has a high throughput and the blood goes through a capillary tube. The counting chamber applied an electrical field which is changed as the cells move through producing characteristic changes in current. This is then interpreted by a machine. We can also differentiate with different kinds of white cells

Answer 54

he most common white cells are neutrophils. This is reflected in the WBC count. We will see subtle differences in different labs, especially in neutrophils because there are ethnic variations. These variations do not indicate illness, they are just the normal ranges for different ethnicities. This may reflect on the normal range of the lab depending on where it is, even within a city. Lymphocytes are the second most common, and have less variation between ethnicities – usually accepted as a global normal. These cells do different things and are from different lineages within the development

Answer 55

If you have doubt about something and the results don’t quite fit, you can make a blood film. To do this you take a drop of blood and then take a slide and put a 40* angle onto it, pull back a bit so it spreads and then slide forward so you are spreading the blood thin enough to look at individual cells. After this is done it needs to be fixed and stained to be looked at and investigated

Answer 56

There are 2 main components: 1. Azure B or Methylene Blue – basic dyes 2. Eosin Y – acidic dye Buffer: pH 6.8 To separate the white cells we will need two different stains. Basophillic stain (blue) and azurophilic stain (red). Some will stain blue and some will stain red allowing differentiation

Answer 57

What you end up with is the staining of everything. Neutrophils are the most common cells. We can recognise that these are neutrophils because they have a segmented nucleus (polysegmented). Up to five segments is normal and this can be easily recognised. They become this way as they mature

Answer 58

They are different as they have a single round nucleus with a variable amount of cytoplasm. Some have more cytoplasm than others. When they become activated or reactive through infecition, they may change their morphology between

Answer 59

The major role of the lymphocytes is adaptive immune response, the differentiation between self and non-self. Eg viral attack, lymphocytes produce antibodies to destroy that virus, memory cells are produced

Answer 60

The two basic divisions of the immune system are the adaptive and innate system. The innate system kills when and where it needs to. The two parts are integrated into one another and they don’t function independently but work as one

Answer 61

There are three major types of lymphocytes: - T cells - B cells - Natural killer (NK) cells These work together to initiate an immune response when you need it. They are naïve when you are born. The first virus you come across will activate a certain number of clones of the pre existing lymphocyte repertoire and want to kill it. T cells are triggered directly and detect the virus/infected cells and kill it. B cells make antibodies which bind to organisms and coat cells that are affected by viruses. Natural killer cells mostly directly kill the infected cells and cancer cells – abnormal cells. T cells are involved in cell-mediated immunity - CD4+ T-Helper cells - CD8+ Cytotoxic T-cells B cells in humoural immunity ie antibody production NK cells are part of the innate immune system attacking virally infected cells and tumour cells

Answer 62

These cells become abnormal when they are infected by viruses. Part of the virus is expressed on the surface of cells and they start looking different; altered self. This is how the immune system recognises and destroys cells. If you couldn’t do this, you would die of autoimmune disease and you wouldn’t be able to differentiate between your own cells. You also wouldn’t be able to absorb food etc as it would all see foreign. The immune system is programmed to tolerate, and it may switch and make an immune response when you need it to. The nucleus of resting lymphocytes is roughly the same size as a red blood cell. The blue cytoplasm comes from antibodies staining blue

Answer 63

A proportion of lymphocytes may look like this. They are large granular lymphocytes. It can be natural to see when fighting infection, for example in leukaemia there is a clinical expansion of these. Activated T cells into natural killer cells look like this

Answer 64

Monocytesa re the next most commonly seen WBC. They are part of the innate immune system and they are phagocytosing cells. These don’t have visible granules like the lymphocytes but the nucleus can be funny, irregular shapes. They are recognised by this characteristic as well as by their colour which is grey blue and no visible in cytoplasm and there are often vacuoles within the cytoplasm

Answer 65

Eosinophils are also recognised quite easily. Eosinophils are recognised by the polynucleotide and granules. They also have granules but are more red than the neutrophils. There are very few basophilic granules. They are eosinophilic. These cells fight a specific corner that provides protection against parasites, especially in the gut. They also have involvement in allergic reactions. The gut reactions and allergies can show degranulation of eosinophils – antihistamines. They are present in eczema, asthma, worms and GI parasites

Answer 66

These are the rarest of the WBC in the blood. Sometimes none will be seen in a blood film. If there are too many it can be associated with certain malignancies. Blood is arguably the least important place for them to be – they go out into tissues to survey tissues and do their job and then they die. The typical life span of a basophil is less than one day – it goes where it is needed, fights infection and then dies

Answer 67

Because they don’t live long we need good production of them in the bone marrow. We need millions produced every second to keep up with what you need. They start dividing in the bone marrow and are becoming more committed progenitors. The stem cell can be anything. The reason we don’t run out of stem cells is because of asymmetric division. They go through a number of precursor stages in the bone marrow, and the whole process takes 7-10 days

Answer 68

The physiological response to most infections is to increase neutrophils and push them out. Certain drugs can cause neutropenia, such as chemotherapy

Answer 69

when they become activated they change how they look

Answer 70

``` Myeloblast promyelocyte myelocyte metamyelocyte band form segmented neutrophil ```

Answer 71

six or more segments make the neutrophil hyperhsegmented. this can be caused by a deficiency in vitamin B12, for example.

Answer 72

These are rather non-specific. Some innate problems can be seen. They are a glomerulus of large blue granules, forming one large blue longitudinal shaped thing. They can be seen in conditions of infection or inflammation and are a good thing to know. They usually go alongside toxic granulation as well. There are three tongs in this neutrophil. Body, granulation and not fully mature segmented neutrophil is a slightly earlier precursor which sometimes pushes out into the blood, sometimes in response to infection/inglammation

Answer 73

Normal physiological reaction: - Post-operative - Pregnancy Other causes: - Bacterial infection - Inflammation eg vasculitis, myocardial infarction - Carcinoma - Steroid treatment - Myeloproliferative disorders - Treatment with myeloid growth factors This can be in response to stress, autoimmune disorders, steroids, pregnancy. Neutrophils try to go to the side of the blood vessels because they leave the blood vessels. In steroids they become more in the middle which is why there is an increase when blood is drawn. Is this a normal response to stress of the system? If it is without any real reason then it is called myeloproliferative disorder

Answer 74

* FBC and differential white cell count * Blood film examination * Bacterial culture screen for infection * Bone marrow examination and chromosome analysis for chronic myeloid leukaemia – Philadelphia chromosome: translocation between chromosomes 9 and 22, molecular analysis for BCR-ABL oncogene The white cell count makes you want to do a blood film. We want to look at the chromosomes in the cells of blood vessels. We may see characteristic translocation between chromosomes driving this growth and we now have treatments for these things. We can recognise, detect and monitor the treatment

Answer 75

* Viral infection * Drug induced eg sulphonamides * Radiotherapy and chemotherapy * Part of a pancytopenia in bone marrow failure (aplastic anaemia) or infiltration eg leukaemia * Racial: ‘benign ethnic neutropenia’

Answer 76

They are bi-lobed with big red granules. This could also be a malignant process. Part of the stem cell is destined to be an eosinophil. Are there lost of basophils for example? * Allergic diseases eg asthma, hayfever * Parasitic infections * Drug sensitivity * Myeloproliferative diseases eg chronic myeloid leukaemia * Hidgkin’s lymphoma Allergic diseases will bring up eosinophils and the differential is very wide. It is important therefore not to jump to conclusions, but to report what you see and seek further information

Answer 77

* FBC and differential white cell count * Blood film examination * Stool examination for ova and parasites * CLARIFICATION!

Answer 78

These are recognised as bigger cells with irregular shaped nuclei. They have pale grey blue cytoplasm and there is no prominent granulations but some have vacuoles. * TB * Acute and chronic monocytic and myelomonocytic leukaemia * Malaria (chronic, not so much acute)

Answer 79

* FBC and differential white cell count * Blood film examination: for abnormal white blood cells and for malarial parasites * Bone marrow examination – leukaemia * TB cultures

Answer 80

Some are clear cut, big square monocytes. The morphology alone may not get you to know what something is, so you could have to use certain stains etc and send them away to find out with phenotyping etc. There could be something malignant in this picture…

Answer 81

Normal physiological status: • Lymphocytosis of childhood (1-6 years) normal: 5.5-8.5x10^9/L Other causes: • Bacterial infection • Viral infections eg hepatitis, mumps, rubella, pertussis, glandular fever, (infectious mononucleosis) • Leukaemias and lymphomas Higher in early life and drops down and reaches normal range in teenage life

Answer 82

* FBC and differential white cell count | * Blood film examination

Answer 83

This may be seen in glandular fever etc. All the glands produce these. They are not malignant, they are blasts – reactive T cells often look like this. They envelope the red cells. Peripheral basophilia is present which means there is a blue ring around the red cells. This may be how blood cells look after glandular fever for example, or anything that drives a strong T cell immune response

Answer 84

Glandular Fever Heterophile antibodies are antibodies which react against an antigen which is completed unrelated to the antigen which originally stimulated it eg human antibodies reacting against sheep or horse or bovine cells

Answer 85

This is the modern way of testing. There are antibodies that will detect antibodies. If they are in the serum moving upwards and we put on a secondary antibody that will recognise them, we will get a control line. When we see the second line occurring this may show mononucleosis. This may not work in the first few days of infection because they take a while to develop – so a repeat should be suggested

Answer 86

Mature lymphocytes: chronic lymphocytic leukaemia? Lymphoma? Immunophenotyping to determine if lymphocytes are: - B cells: demonstrate clonality by light chain restriction - T cells: demonstrate clonality by T-cell receptor gene rearrangement studies

Answer 87

Antigens are part of the surface of cells • All blood cells have antigens Reactions to blood usually occurs when the antibody in the plasma reacts with an antigen on the cells. * There are 26 known blood group systems * ABO and Rh are clinically most important * Antigens in transfused blood can stimulate a patient to produce an antibody but only if the patient lacks the antigen themselves * The frequency of antibody production is very low but increases the more transfusions that are given

Answer 88

Antibodies are protein molecules – immunoglobulins (Ig) • Usually of the immunoglobulin classes: IgG and IgM • Found in the plasma • Produced by the immune system following exposure to a foreign antigen

Answer 89

* Blood transfusion: ie blood carrying antigens foreign to the patient * Pregnancy: fetal antigen entering maternal circulation during pregnancy or at birth * Environmental factors: ie naturally acquired eg anti-A and anti-B

Answer 90

``` In vivo (in the body) – leads to destruction of the cell either: Directly when the cell breaks up in the blood stream (intravascular) Indirectly when liver and spleen remove antibody coated cells (extravascular) ``` ``` In vitro (in the laboratory) Reactions are normally seen as agglutination tests ```

Answer 91

* Agglutination is the clumping together of red cells into visible agglutinates by antigen-antibody reactions * Agglutination results from antibody cross-linking with the antigens

Answer 92

As the antigen-antibody reaction is specific, agglutination can identify: • The presence of a red cell antigen: ie blood grouping • The presence of an antibody in the plasma: ie antibody screening/identification

Answer 93

* A and B antigens very common (55% UK) * Anti-A, anti-B or anti-A,B antibodies very common (97% UK) * High risk of A or B cells being transfused into someone with the antibody in a random situation * ABO antibodies can activate complement causing intravascular haemolysis (Almost) all serious/fatal transfusion reactions caused by technical/clerical error are due to ABO incompatibility

Answer 94

The patients red cells and plasma are both tested. Test patient’s red cells with anti-A, anti-B and anti-D • Agglutination shows that a particular antigen is on the red cells • No agglutination shows the antigen is absent Test patient’s plasma with A cells and B cells • Agglutination shows that a particular antibody is in the plasma or serum • No agglutination shows the antibody is absent

Answer 95

50+ antigens: • Most important antigen is called D • People with D antigen are RhD positive (85% of UK) • People who do not produce any D antigen are RhD negative (15%) • The other 4 main Rh antigens are known as C, c, E and e

Answer 96

* Most important after ABO * Must be tested in duplicate (or tested each time and compared to historical result) * Patient/donor classified as RhD pos or RhD neg

Answer 97

Rh antibodies are clinically significant. Second only to ABO. Transfusion: • D antigen is very immunogenic and anti-D is easily stimulated – PREVENTION! • All Rh antibodies are capable of causing severe transfusion reaction – ANTIBODY DETECTION Pregnancy: • Rh antibodies are usually IgG and can cause haemolytic disease of the newborn • Anti-D is still most common cause of severe HDN

Answer 98

* Blood group and antibody screen at antenatal booking to identify pregnancies at risk of HDN – RhD negative women who may need anti-D prophylaxis * Blood group and antibody screen at 28 weeks * Atypical antibodies are quantified periodically to assess their potential effect on the fetus

Answer 99

* An injection of anti-D will bind to and remove any fetal RhD positive red cells in the circulation * 1500 iu of anti-D is given routinely at 28 weeks and a smaller dose (usually 500 iu) after delivery if baby RhD+ * in some hospitals 2 smaller (500 iu) doses are given at 28 and 34 weeks instead of the 1 larger dose * anti-D is also given after any event that may cause a feta-maternal haemorrhage (bleed between mum and fetus) such as: * abdominal trauma * intrauterine death * spontaneous or therapeutic abortion

Answer 100

* there are other clinically significant antibodies that can cause a haemolytic transfusion reaction * it is important that we screen for these antibodies so that if detected, antigen negative blood can be provided to avoid causing an immune reaction * patients serum is mixed with 3 selected screening cells, incubated for 15 minutes at 30^C and then centrifuged for 5 minutes * any clinically significant antibodies reacting at body temperature should be detected and then identified using panel of known phenotyped red cells * specific antigen negative blood can then be provided for these patients to avoid stimulating an immune response

Answer 101

* identify the antibody | * assess its clinical significance: for transfusion, in pregnancy

Answer 102

* compare pattern of reactions with each reagent cell of ID panel with the pattern fo antigens on the reagent cells * matching pattern will identify the antibody

Answer 103

the potential difference existing between the surface of a solid particle immersed in a conducting liquid (e.g. water) and the bulk of the liquid. IgM antibodies can span the gap between RBCs. IgG can not, because it is too small to overcome the ZETA potential (positive chage). LISS (low ionic strength saline) is negatively charged, so neutralises positive ZETA potential. Therefore, IgG can now span the gap

Answer 104

``` • used to detect IgG antibodies • LISS counteracts Zeta potential • Results in agglutination • Used for: • Screening for antibodies • Identifying antibodies Cross matching donor blood with recipient plasma when there are known antibodies or a previous history of antibodies ```

Answer 105

* Antibody screen is negative * Checking donor red cells against patients plasma: ABO check, incubate for 2-5 minutes (room temp), spin and read ISX – basically just checking the ABO group. Therefore IgM antibodies (therefore no problem with ZETA potential, therefore no need to IAT).

Answer 106

* Antibody screen positive or patient has known antibody history * Select antigen negative donor red cells and incubate with patient serum for 15 minutes at 37^C

Answer 107

* Blood establishment: MHRA licensed manufacturer of blood and products * Donor selection: questionnaire; lifestyle, health, not previously transfused * Collection procedure arm cleansing/diversion pouch * Comprehensive testing of all products: Viral; HIV 1+2, hepatitis B, hepatitis C, syphilis, HTLV * Platelets: bacteria

Answer 108

* 1 in 910,000 for hepatitis B * 1 in 70 million for hepatitis C * 1 in 5 million for HIV infection * 1 in 23 million for HTLV infection There are believed to have been 4 cases of infected with vCJD from blood transfusion

Answer 109

• FFP contains all clotting factors - Given for coagulopathy with associated bleeding - Requires clotting screens to monitor • Only has 24 hour life after thawing

Answer 110

* Adult pool of platelets fro 4 donors (suspended in plasma from 1 donor) * 85% of doses are apheresis units * platelets required to create clots to reduce bleeding * some drugs given to reduce efficacy of platelets (anti-platelet agents) so patient history is important

Answer 111

Contains factor VIII, VWF and fibrinogen - 2 units usually given at one time - monitor fibrinogen levels by clotting screens

Answer 112

* EU Blood Safety Directive * Blood Safety Quality Regulations * Better Blood Transfusion 3 * MHRA inspections * CPA inspections

Answer 113

Serious hazards of transfusion (SHOT): - Voluntary reporting - Report all serious adverse events (SAE) and serious adverse reactions (SAR) Serious adverse blood reactions and events (SABRE): - Mandatory reporting - Report all SAR and SAE where the root cause error was the quality system

Answer 114

Blood glucose levels are maintained from several sources: • Dietary carbohydrate • Glycogenolysis • Gluconeogenesis Livers role: • After meals: stores glucose as glycogen • During fasting: makes glucose available through glycogenolysis and gluconeogenesis

Answer 115

* Brain and erythrocytes require continuous supply – avoid deficiency * High glucose and metabolites cause pathological changes to tissues; eg, micro/macro vascular diseases, neuropathy – avoid excess

Answer 116

* Peptide hormone (51 amino acids) * Synthesised in -cells of pancreas as proinsulin; cleaved to insulin and C-peptide * Secretion is stimulated by rise in blood glucose

Answer 117

Glucagon • Secreted by alpha-cells of pancreas in response to hypoglycaemia • Stimulates glycogenolysis and gluconeogenesis Adrenaline • Increased glycogenolysis and lipolysis Growth Hormone • Increased glycogenolysis and lipolysis Cortisol • Increased gluconeogenesis, glycogen synthesis

Answer 118

Metabolic disorder characterised by chronic hyperglycaemia, glycosuria and associated abnormalities of lipid and protein metabolism. • hyperglycaemia result of increased hepatic glucose production and decreased cellular glucose uptake • blood glucose > ~10mmol/L exceeds renal threshold – glycosuria • long term complication – micro-macrovascular disease

Answer 119

* globally 415 million people currently have diabetes; estimated to double by 2030 * estimated prevalence of diabetes in UK 2013 was 3.2 million (ages 17+) * number of people in UK with diabetes has more than doubled since 1996 (1.4 million)

Answer 120

* increased awareness * more complete recording * poor diet * low physical activities

Answer 121

In the presence of symptoms: (polyuria, polydipsia weight loss) • random plasma glucose > 11.1 mmol/l (200 mg/dl) OR • fasting plasma glucose > 7.0mmol/l (126 mg/dl) fasting is defined as no caloric intake for at least 8 hours OR • 2-h plasma glucose > 11.1 mmol/l (200 mg/dl); 2hrs after 75g oral glucose tolerance test (OGTT) In the absence of symptoms: • test blood samples on 2 separate days

Answer 122

Impaired glucose tolerance (IGT) • fasting plasma glucose 6.1-6.9 mmol/L** • OTTG value of

Answer 123

• OGTT should be carried out: o In patients with IFG o In unexplained glycosuria o In clinical features of diabetes with normal plasma glucose values o For the diagnosis of acromegaly • 75g oral glucose and test after 2 hours • blood samples collected at 0 and 120 mins after glucose • subjects tested fasting after 3 days of normal diet containing at least 250g carbohydrate

Answer 124

TYPE 1: insulin secretion is deficient due to autoimmune destruction of beta-cells in pancreas by T-cells TYPE 2: insulin secretion is retained but there is target organ resistance to its actions GESTATIONAL: occurs for first time in pregnancy SECONDARY: chronic pancreatitis, pancreatic surgery, secretion of antagonists

Answer 125

* predominantly in children and young adults’ but ages also * sudden onset (days/weeks) * appearance of symptoms may be preceded by ‘prediabetic’ period of several months * commonest cause is autoimmune destruction of B-cells * interaction between genetic factors and environment * strong link with HLA genes within the MHC region on chromosome 6

Answer 126

• HLA class II cell surface present as foreign as self antigens to T-lymphocytes to initiate autoimmune response • Circulating autoantibodies to various-cell antigens: o Glutamic acid decarboxylase o Tyrosine-phosphatase-like molecule o Islet auto-antigen • The most commonly detected antibody associated with type 1 DM is the islet cell antibody • More than 90% of newly diagnosed persons with type 1 DM have one or another of these antibodies • Destruction of pancreatic beta-cell causes hyperglycaemia due to absolute deficiency of both insulin and amylin • Amylin, a glucoregulatory peptide hormone co-secreted with insulin lowers blood glucose by slowing gastric emptying, and suppressing glucagon output from pancreatic cells

Answer 127

* Slow onset (months/years) * Patients middle aged/elderly – prevalence increases with age * Strong familiar incidence * Pathogenesis uncertain – insulin resistance; beta cell dysfunction may be due to lifestyle factors – obesity, lack of exercise * Emergency presentation as hyper-osmolar, non-ketotic state (HONK)

Answer 128

``` Hyper-osmolar non-ketotic coma (HONK) • Development of severe hyperglycaemia • Extreme dehydration • Increased plasma osmolality • No ketosis, minimal acidosis • Impaired consciousness • Death is untreated ```

Answer 129

* Immediate: blood glucose * Few hours: urinary dipstick * 3-4 months: blood HbA1c (glycated Hb, covalent linkage of glucose to residue in Hb) * Others: orinary albumin (index of risk of progression to nephropathy), abnormalities in serum lipids common in T1 and T2 DM – increased risk of MI and stroke

Answer 130

* Prevent complication through tight control * Avoidance of hypoglycaemia * Self-monitoring: capillary blood measurement, urine analysis: glucose in urine gives indication of blood glucose concentration above renal threshold * Glycated Hb (HbA1c) – aim at

Answer 131

* Occur in both type 1 and type 2 DM * Micro-vascular disease: retinopathy, nephropathy, neuropathy * Macro-vascular disease: related to atherosclerosis heart attack/stroke * Exact mechanisms of complications are unclear

Answer 132

* Attain normal weight and waist circumference * Eat food low in fat and salt * Exercise * Stop smoking * HbA1c

Answer 133

• Defined as plasma glucose

Answer 134

* Insulinoma * Drugs eg sulphonylureas, insulin, alcohol abuse * Inherited metabolic disorders eg glycogen storage diseases, galactosaemia, hereditary fructose intolerance * Endocrines disease; eg cortisol disorder * Others: severe liver disease, non-pancreatic tumours, postgastrectomy

Answer 135

• Insulin levels fall, limiting glucose entry into non-cerebral tissues • Hepatic gluconeogenesis stimulated • Glycogen breakdown activated • Fatty acid oxidation activated • Release of counter regulatory hormone raising glucose - Glucagon – (

Answer 136

Neurogenic (autonomic): - Triggered by falling glucose levels - Activated by ANS and mediated by sympathoadrenal release of catecholamines and Ach - Sign and symptoms include shakiness, anxiety, nervousness, palpitations, sweating, dry mouth, pallor and pupil dilation Neuroglycopaenia: - Due to neuronal glucose deprivation - Sign and symptoms include confusion, difficulty speaking, ataxia, paresthesia, seizure, coma and death Insulinoma: - Tumour in the insulin secreting beta-cells of pancreas Symptoms include: - Fasting hypoglycaemia, patients may present with behavioural changes - Inappropriate high insulin concentration at time when plasma glucose is low (

Answer 137

* Glycogen storage disease type I (von Gierke’s disease); deficiency of G-6-Phosphatase: impaired glucose release from glycogen * Galactosaemia: deficiency of galactose-1-phosphate uridyl transferase: liver damage * Hereditary fructose intolerance: deficiency of fructose-1-phosphate adolase B: accumulation of fructose-1-phosphate in liver

Answer 138

* Autosomal recessive disorder (described in 1929) * Glucose synthesis from glycogen or by gluconeogenesis is blocked * Presents in early infancy; severe fasting hypoglycaemia as only source of glucose is dietary carbohydrate * Accumulation of glycogen causes hepatomegly; inability to produce glucose from lactose causes acidosis * Tx: uncooked cornstarch; a slow releasing glucose prep

Answer 139

* Defects in 3 enzymes can cause galactosaemia; most common is galactose-1-phosphate uridyl transferase deficiency * Autosomal recessive disorder (1st described in 1935) * Deficiency of G-1-PUT impairs conversion of galactose-1-phosphate to glucose-1-P gal-1-phosphate accumulates in liver – toxicity * Hypoglycaemia and vomiting/diarrhoea after starting milk feeds * Galactose excreted in urine. Tx – exclude galactose from diet

Answer 140

* Autosomal recessive disorder (1st described in 1956) * Deficiency of fructose 1-phosphate aldolase B when ingested fructose accumulates – inhibits glycogenolysis at phosphorylase step * Severe hypoglycaemia and vomiting after ingesting fruit, sweetened foods * Fructose detected in urine * Avoid ingestion of fructose, sucrose * Benign fructose intolerance: this is due to absence of fructokinase

Answer 141

* These are neural connections between the hypothalamus and posterior (but not anterior) pituitary * Blood form the hypothalamus supplies the anterior pituitary * The secretion of anterior pituitary hormones is regulated by hypothalamic releasing factors

Answer 142

GR-RH (stimulatory) and somatostatin (inhibitory)

Answer 143

PIF (dopamine)

Answer 144

corticotrophin (CRF)

Answer 145

¥ Essential for normal growth and development ¥ Increase basal metabolic rate (BMR) and affect many metabolic processes ¥ Synthesized in thyroid via series of enzyme catalyzed reactions, beginning with uptake of iodine into gland ¥ Synthesis and release controlled by TSH ¥ T4 main hormone secreted by thyroid, T3 is more biologically active – mostly formed by peripheral conversion from T4 ¥ Effects are mediated via activation of nuclear receptor

Answer 146

* Both T4 and T3 are extensively protein bound, principally to TBG * Free (non-protein bound) fraction physiologically active * Changes in protein binding affect total hormone concentrations * Measurement of free hormones is not affected by variation in TBG and so discriminates more reliably between normal and abnormal thyroid function

Answer 147

- Graves disease: most common (TSH-R antibodies) - Toxic multinodular goiter - Toxic adenoma thyroiditis - Excessive TSH production (rare)

Answer 148

excessive production of thyroid hormones

Answer 149

- weight loss - heat intolerance - palpitations - goitre - eye changes

Answer 150

- Serum TSH concentraitons suppressed | - fT4 raised

Answer 151

deficient production of thyroid hormones

Answer 152

- primary: autoimmune thyroiditis, iodine deficiency, post-surgery/antithyroid drugs, congenital - secondary: pituitary or hypothalamic diorder

Answer 153

- weight gain - cold intolerance - lack of energy - goitre - congenital - development abnormalities

Answer 154

- serum TSH concentrations raised - fT4 reduced (primary) - reduction in both TSH+fT4 consistent with hypopituitarism

Answer 155

* anti-thyroid drugs (g carbimazole) * partial thyroidectomy * radioactive iodine * fT4 levels fall rapidly with successful treatment * TSH may remain suppressed for several months

Answer 156

* Thyroxine replacement * fT4 may remain slightly raised * best monitored by TSH (elevated values indicate under/and suppressed values over replacement)

Answer 157

* Aldosterone is the main mineralocorticoid synthesized in (outer) zona glomerulosa * Cortisol is the principal glucocorticoid produced by the zona fasciculate * Glucocorticoids and adrenal androgens are synthesized in zona fasciculate & zona reticularis

Answer 158

Cortisol - antagonizes effects of insulin by enhancing gluconeogenesis - promotes the central deposition of fat - increases catabolism of proteins - weak mineralocorticoid effects - anti-inflammatory Aldosterone - increases sodium reabsorption in renal DCT Androgens - virilizing effects when secreted in excess

Answer 159

* Synthesis of cortisol regulated by hypothalamic - pituitary - adrenal axis * Aldosterone synthesis is controlled by the renin-angiotensin system * Adrenal androgen synthesis is regulated by ACTH, not gonadotrophins

Answer 160

Conn’s syndrome: excess secretion of aldosterone due to tumour or hyperplasia of adrenal - sodium retention ``` Cushing’s syndrome: excess cortisol secretion - causes: - pituitary tumour (Cushing’s disease) - ectopic ACTH production - adrenal tumour - exogenous administration of steroids ```

Answer 161

Due to excessive cortisol production by adrenal. ``` Clinical features include: • muscle weakness • menstrual disturbances • psychiatric disturbances • moon face, truncal obesity • striae, bruising • hirsutism, acne • hypertension • glucose intolerance • osteoporosis ```

Answer 162

1. Demonstration of excessive cortisol production Screening Tests: - Loss of cortisol circadian rhythm - Elevated 12am serum cortisol - Increased 24hr urine cortisol - Inadequate suppression of serum cortisol levels following low dose (1mg dexamethasone) 2. Elucidation of cause - High dose dexamethasone suppression test - ACTH assay

Answer 163

Dynamic tests are important tools in the investigation of endocrine function. There are two types: - Stimulatory test may be used to investigate endocrine gland hypofunction - Suppression tests are used to investigate suspected hyperfunction

Answer 164

Dexamethasone - synthetic glucocorticoid - binds to GC receptors in pituitary to suppress - ACTH release (and cortisol secretion from adrenal) Low dose dexamethasone suppression test - 1mg dexamethasone given at night. Serum cortisol is measured at 9am next morning - in normal subjects, cortisol

Answer 165

``` Causes: Primary adrenocortical failure – Addison’s disease due to : autoimmune disease tuberculosis less common; metastases, haemochromatosis, haemorrhage ``` Secondary to impaired ACTH release eg – tumour, head trauma, surgery, rapid withdrawal of steroids

Answer 166

- fatigue - weakness - hypoglycaemia - hypotension

Answer 167

Short synacthen test - to assess the ability of the adrenal to produce cortisol in response to ACTH Serum cortisol is measured after giving synacthen (synthetic ACTH) (normal response – cortisol increases by >200nmol/L over basal level with peak of >550nmol/L).

Answer 168

Long synacthen test - 3 day stimulation with 1mg depot synacthen i.m. daily In secondary adrenal hypofunction, serum cortisol levels increase to at least 200nmol/L over baseline values

Answer 169

¥ Group of inherited metabolic disorders of adrenal steroid hormone biosynthesis ¥ Clinical features depend on the position of enzyme defect in metabolic pathway ¥ 21-hydroxylase deficiency > 90% cases, prevalence 1:5000-12,000 Leads to impaired production of cortisol and aldosterone. Raised ACTH stimulates production of adrenal androgens

Answer 170

¥ Virilization of female infants ¥ Salt wasting and dehydration occurs during first 4 weeks of life, serum Na 2 days after birth ¥ Requires glucocorticoid and mineralocorticoid replacement ¥ Treatment monitored by measurement of either plasma 17a-hydroxyprogesterone or androstenedione

Answer 171

¥ Condition of excess androgen secretion and chronic anovulation ¥ Ovaries are the source of excess androgens and there are multiple ovarian cysts ¥ Associated with menstrual disturbances, hirsutism and infertility ¥ Many patients with PCOS are overweight and a link has been made with insulin resistance ¥ Increased serum LH:FSH ratio ¥ Decreased SHBG

Answer 172

- Tumours eg pituitary adenoma - Trauma/ head injury - Hypothalamic disorders - Vascular disease - Infection – eg meningitis - Iatrogenic – eg therapeutic skull irradiation - Miscellaneous – eg sarcoidosis, haemochromatosis

Answer 173

Destructive lesions of the pituitary tend to present with pituitary hypofunction, thus stimulatory tests are used toassess the ability of the gland to secrete hormones. In assessing patients with suspected anterior pituitary dysfunction, it is often convenient to test the capacity of the gland to secrete GH, ACTH, TSH and the gonadotrophins in a single procedure – the combined pituitary function test. This involves measurement of anterior pituitary hormones following adminstration of TRH, GnRH and insulin

Answer 174

* GH deficiency in children is a cause of growth retardation * The diagnosis depends on the demonstration of subnormal growth velocity and subnormal serum growth hormone concentrations * While a random growth hormone concentration >20mU/L excludes significant deficiency, a low level is not diagnostic * GH status can be measured by a number of stimulatory tests

Answer 175

¥ Pituitary tumours may be functional, producing excess hormone secretion ¥ Prolactin, GH and ACTH secreting tumours are well recognised ¥ Gonadotrophin and TSH secreting tumours are rare ¥ Since the presence of the tumour may give rise to destructionof normal pituitary tissue, decreased production of other hormones should be investigated with the combined pituitary function test

Answer 176

¥ Acromegaly is the result of excessive GH secretion by a pituitary tumour leading to increased growth of soft tissue/bone increase in size of hands, feet, jaw change in facial appearance ¥ GH concentration in a random serum sample usually raised ¥ Diagnosis confirmed biochemically by demonstrating failure of suppression of GH levels in response to oral glucose ¥ Treatment options – surgery, external irradiation, drugs ¥ Accompanying hypopituitarism requires appropriate treatment with cortisol, sex steroids and thyroxine

Answer 177

Carbohydrate metabolism • Gluconeogenesis • Glycogen synthesis and degredation ``` Lipid Metabolism • Fatty acid synthesis • Cholesterol synthesis and excretion • Lipoprotein • Ketogenesis • Vitamin D 25-OH • Bile acid synthesis and excretion ``` Protein metabolism • Plasma protein • Ammonia detoxification Bilirubin metabolism Hormones • Conjugation of steroid hormones • Degradation of peptide hormones Xenobiotic metabolism ``` Storage • Vitamin A • Glycogen • B12 • Iron ```

Answer 178

¥ Liver has a considerable functional reserve, and therefore simple tests of liver function as bilirubin or albumin concentrations are insensitive indicators of disease ¥ Tests reflecting liver cell damage are more sensitive, e.g., hepatic enzymes in plasma ¥ True tests of liver function, e.g., bromsulphophthalein (BSP), indocyanin green, caffeine clearance and radio-labelled bile acid uptake and clearance tests are available for research purposes Biochemical tests usually reflect the basic pathological processes common to many conditions, and rarely provide a precise diagnosis, However, they are cheap, non-invasive, and can direct other investigations, e.g., liver biopsy and imaging. They are useful in detecting the presence of a liver disease and in monitoring progress

Answer 179

* Aid in establishing liver disease by showing abnormal values * Inform or help specific diagnosis by showing different patterns * Establish the severity of liver damage and provide prognostic insight * Monitor disease progression * Assess response to therapy

Answer 180

o Derived from the break down of haem of senescent PBCs, and to a lesser extent from myoglobin, cytochromes and some enzymes o Being water insoluble, it is transported in the plasma to the liver by albumin. At this stage, bilirubin is unconjugated and can not pass in urine even if present at high level o Unconjugated bilirubin is taken up by liver cells to be conjugated with glucuronic acid by the enzyme UDP-glucuronyl transferase to produce bilirubin diglucuronide which is water soluble and s called conjugated bilirubin which is then secreted into bile and eventually reaches the intestine where more of it is oxidised by bacteria to urobilinogen and stercobilin o A small amount of urobilinogen and bilirunin are reabsorbed through entero-hepatic circulation to be secreted in urine Total bilirubin reference range (RR): 3-17 micromol/l Plasma bilirubin rises when significant liver damage occurs and causes yellowish discolouration of skin and mucous membranes (Jaundice) which can be clinically detected at bilirubin level of 50 umol/l

Answer 181

* Investigate liver diseases and assess subclinical hyperbilirubinaemia * Determine the need for exchange transfusion in neonatal jaundice * Assess surgical treatment of bile duct stricture * Determining correct doses of drugs, e.g., cytotoxic therapy

Answer 182

Alkaline phosphatase (ALP): (RR: 30-130 U/I) o A group of enzymes that hydrolyse phosphate esters at alkaline pH and are present in liver, bone, intestine and placenta. Plasma ALP increases in the presence of obstruction to the biliary passages or cholestasis. The block could be intrahepatic as in PBC, or due to a stone in the bile duct or pressure by a tumour, e.g., head of pancreas or lymph nodes o ALP increases in liver and bone disease, with pregnancy, growing children and to enhance the specificity, ALP isoenzymes can be measured using electrophoresis or utilising different thermal stabilities of iso-enzymes, as liver isoenzyme activity drops by 40% after 15 min incubation at 56oC while bone isoenzyme activity decreases only by 15% or gGT is used

Answer 183

Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) (RR: 0-40 U/l for both) o Also called transaminases as they transfer an amino group from an amino acid to a keto acid. They increase in the plasma in presence of liver cell damage. o They have wide tissue distribution, with AST present in liver, heart, skeletal muscle, kidney, brain, erythrocytes and lung. ALT has also a similar wide tissue distribution but activities are lower in extrahepatic tissues, and increased plasma ALT is more specific for liver disease (CK for muscle and troponins for heart) o Aminotransferase activity above 10 times the upper limit of RR are most frequently due to hepatocellular damage, e.g., viral or drug induced hepatitis or autoimmune hepatitis o Aminotransferase activity below 10 times the upper limit of RR, but higher than upper limit of RR are less specific but could occur in chronic liver diseases o Aminotransferase activities within RR do not exclude liver disease that could be assessed by histological examination of a biopsy specimen o The higher the AST/ALP ratio, the more likely the underlying condition to be a form of hepatitis. The lower the ratio, the more it is indicative of cholestatic disorder o An AST/ALT ratio of more than 2 in a patient who clinically appears to have hepatitis strongly suggests that alcohol is involved

Answer 184

Accounts for 80% of total AST in liver cells and the ratio of mAST/total AST is a good marker for chronic alcohol consumption

Answer 185

o A microsomal enzyme that transfers glutamyl groups between peptides and aminoacids and is involved in the transport of peptides across plasma membranes. o Plasma activity is mainly derived from liver, despite its wide distribution, and it has a poor specificity and high sensitivity for liver disease o Its measurement helps in linking an elevated ALP to the liver and is elevated with chronic alcohol consumption and is more elevated in the presence of chronic liver disease with alcohol consumption

Answer 186

Albumin: (RR: 30-50 g/l) o Synthesised exclusively by liver and its plasma half-life is 21 days. It maintains plasma oncotic pressure, binds calcium, fatty acids, bilirubin, some hormones and drugs. o Its level tends to fall with progress of chronic liver disease and therefore plays a major prognostic role. It also falls with inadequate protein intake

Answer 187

Measures the rate at which prothrombin is converted to thrombin in the presence of thromboplastin, calcium, fibrinogen, and coagulation factors V, VII and X.

Answer 188

INR is the ratio of the PT of the patient to that obtained using a control preparation. Normal individuals have an INR

Answer 189

In the presence of severe acute or chronic liver damage, the synthesis of clotting proteins by the liver is impaired . Prothrombin half life is 6 hours and therefore, a prolonged INR which can only be improved by fresh plasma transfusion or providing the deficient clotting factors is a good indicator of severe liver damage, e.g., acute liver failure Vitamin K is a fat soluble vitamin and requires bile salts from liver for absorption. It is also needed for the synthesis of clotting factors by the liver. In case of cholestasis, vitamin K absorption is defective and the synthesis of clotting factors is impaired causing an increased INR which can be corrected within 24 hours by an injection of vitamin K

Answer 190

Is relatively common in Southeast Asia, Sub-Saharan Africa, Japan, Pacific Islands and Mediterranean area. UK incidence ranges between 1-7/100 000. Incidence in some tribes in Mozambique is 107/100 000. Individuals who migrate from areas of high incidence to areas of low incidence of HCC have lower incidence compared with the population remaining in lands of origin. Therefore, environmental factors, rather than genetic or racial predisposition, play a key role in pathogenesis of HCC. In recent years, the incidence of HCC seems to be rising in the West, as a result of improved treatment of alcoholic and other cirrhosis (e.g., after hepatitis B or C) and more prolonged survival. Incidence rates of about 10/100 000 have been reported

Answer 191

In low-incidence populations, the tumour usually presents in a patient who is known to have had cirrhosis or haemochromatosis for some time. In high incidence areas, it appears in individuals who were apparently healthy. However, the majority of affected patients are found to have cirrhosis in non-tumour part of liver

Answer 192

Usually runs a silent course until advanced where it presents with: • Upper abdominal discomfort or pain, in the right hypochondrium or epigastrium, radiating to the right sub-scapular region or shoulder • Weight loss and weakness • Feeling of fullness in the upper abdomen after meals/ anorexia • Generalised swelling of the abdomen (due to ascites) • Nausea, vomiting, constipation • Peritoneal haemorrhage (acute abdomen due to tumour rupture ) • Bone pain due to skeletal metastasis

Answer 193

* Early: Mild to moderate hepatomegaly, but later: Massive enlargemen, tenderness * Hepatic arterial bruit, ascites heard, splenomegaly, jaundice, wasting, fever * Stigmata of chronic liver disease: gynaecomastia, caput medusae, feminisation * Ectopic Hormonal Syndromes: erythrocytosis, hypercalcaemia, feminisation (dehydroepiandrosterone converted to oestradiol by the tumour) * Hypoglycaemia, hypercholesterolaemia, porphyria * Elevated a-fetoprotein, carcino-embryonic antigen (CEA), dysfibrinogenaemia

Answer 194

• Determination of a-fetoprotein: markedly elevated • Biochemistry: similar to cirrhosis: markedly elevated alkaline phosphatase with normal or slightly elevated bilirubin and transaminases, low albumin and elevated IgG and IgM Radiologic Investigations: isotope liver scanning (figures), hepatic angiography, ultrasonography (solid vs cysts), CT scans

Answer 195

* Surgical Resection: partial hepatectomy, hemihepatectomy offer the only chance of cure of HCC. Tumour should be confined to one lobe and the rest of the liver free from cirrhosis or only have mild cirrhosis * Liver transplantation * Chemotherapy: 5-Flurouracil, cyclophosphamide, methotrexate, vincristine. * External irradiation

Answer 196

H. Pylori infection is the main cause of duodenal or gastric ulcers and plays an important role in gastric cancer. It can be diagnosed by microscopical examination of biopsy specimens. Alternatively, biopsies could be tested for the presence of urease, which is specific for H. Pylori, in the presence of an indicator that changes colour with the release of ammonia in case of positive biopsies. Antibodies for H. Pylori can also be checked but C13 or C14 urea breath test of PCR are preferred

Answer 197

Exocrine: • Alkaline secretion • Enzymes: amylase, lipase, trypsin, chymotrypsin, carboxypeptidases, elastase, esterases, phospholipases • Bile salts and lipases are essential for fat digestion and absorption and absorption of fat soluble vitamins A, D, E, K Endocrine: • Insulin • Glucagon • Somatostatin

Answer 198

Pain: upper abdominal, radiates to the back Enzymes marked elevation of amylase and lipase in blood and urine ``` Aetiology • Alcohol • Gallstones • Post-operative • Hyperlipidaemia • Traumatic • Carcinoma • Drugs: steroids, azathioprine, diuretics ```

Answer 199

``` Biochemistry: • serum or urine amylase or lipase (high) • serum calcium (low) • falling arterial O2 tension • coagulopathy ``` ``` Radiology and imaging (figures) • plain radiography • ultrasonography • computerized tomography (CT) • ERCP • PTC ```

Answer 200

affects 10-20% of world population 1. Cholesterol stones: >70% cholesterone, mucoprotein ± calcium • Supersaturation • Nucleation • GB motor dysfunction 2. Pigment stones: calcium bilirubinate, cholesterol, calcium soaps and mucoprotein matrix • Bacterial beta-glucuronidase

Answer 201

* Symptomless * Biliary obstruction * Cholangitis * Cholecystitis * Jaundice * Intestinal obstruction

Answer 202

- Polymorphonuclear leukocytosis - Increased alkaline phosphatase - Elevated bilirubin - Increased amylase Abdominal radiograph: calcified gallstone Ultrasonography: gallstones in GB

Answer 203

Hepatocellular: - Viral or alcoholic hepatitis - Sex hormones and pregnancy Biliary: - Intrahepatic atresia - Primary biliary cirrhosis - Sclerosin cholangitis - Malignancy

Answer 204

The incidence has doubled in UK over the past 50 years to 10/100 000/year. It is twice as high in men than in women, and over 80% of cases occur in the 60-80 y age group. Risk Factors: • Tobacco: cigarette smoking is associated with PC, with a relative risk of 2-3 over non-smokers. • Diet: Increased animal fat, combined with increased alcohol consumption, are associated with increased incidence of PC. The fish oil fatty acids (eicosapentaenoic and docosahexaenoic acids) seem to antagonise the carcinogenic effect. Vegetables and fruit are protective • Coffee: prolonged intake of higher amounts of coffee might be linked to PC • Chronic Pancreatitis • Diabetes mellitus • Gastric resection

Answer 205

Symptoms: - Pain: is the presenting feature in 50-80% of cases, usually dull aching or boring pain in the epigastrium and radiates to the back. It is aggravated by food intake and may be worst in recumbent position and eased by sitting. - Jaundice: is the 1st symptom in 10-30% of patients and the presenting symptom in 30-65%. It is progressive until releived by surgery or stenting. Pruritus is common. - Weight Loss: is the presenting feature in 90% of patients, usually rapid and progressive. - Other Symptoms: Fatigue, weakness, epigastric bloating, diarrhoea, steatorrhoea, or constipation. Nausea and vomiting occur in 25% of patients Signs: - Jaundice - Hepatomegaly - a palpable gallbladder and epigastric tenderness - ascities - enlarged lymph nodes

Answer 206

- Imaging Techniques: CT scanning, ERCP, PTCA, US, angiography (Figures) - Blood Tests: ESR, CRP, Blood count, LFTs, enzymes: amylase, lipase, pancreatic elastase, tumour markers: DU-PAN 2, CEA, CA 19-9, CA 50

Answer 207

- Pre-operative biliary drainage - Palliative surgery - Curative resection: prognosis and complications - Chemotherapy: 5-flurouracil, cyclophosphamide, methotrexate, vincristine - Radiotherapy

Answer 208

* Screening (subclinical conditions) * Diagnosis (normal vs abnormal values) * Monitoring (course of disease) * Clinical management (treatment/response) * Prognosis (risk stratification)

Answer 209

* Located in the myocardium * Released in response to cardiac overload * Released in response to cardiac injury * Released in response to cardiac failure * Can be measured in blood samples

Answer 210

* Markers of risk factors for development of coronary artery disease * Genetic analysis for candidate genes of risk factors * Markers of cardiac tissue damage * Markers of myocardial function/overload

Answer 211

* Rule in/out an acute MI * Confirm an old MI * Help to define therapy * Monitor success of therapy * Diagnosis of heart failure * Risk stratification of death

Answer 212

Analytical characteristics - Measureable by cost-effective method - Simple to perform - Rapid turnaround time - Sufficient precision and accuracy - Reasonable cost Clinical Characteristics - Early detection of disease - Sensitivity vs specificity - Validated decision limits - Selection of therapy - Risk stratification - Prognostic value - Ability to improve patient outcome

Answer 213

Stable angina vs acute myocardial infarction - Treatment - Prognosis - Management

Answer 214

* Broken rib * Collapsed lung * Nerve infection (shingles) * ‘pulled’ muscle * infection * heart burn (hernia) * pericarditis * blood clot in the lungs (PE) * angina * myocardial infarction

Answer 215

- medical history - risk factors - presenting signs and symptoms - ECG - Biomarkers - Imaging/scans

Answer 216

In general, an ST elevation MI is caused by complete obstruction of a coronary artery, and causes damage that involves the full thickness of the heart muscle. A non-ST elevation MI is caused by partial obstruction of a coronary artery, and causes damage that does not involve the full thickness of the heart wall

Answer 217

* Irreversible injury typically requires 30 minutes of ischaemia * High risk that 80% of cardiac cells die within 3 hours and almost 100% by 6 hours * Cellular content leak out through membrane dependent on size and solubility * Concentration gradient from inside to outside important (high gradient improves detection of early damage)

Answer 218

* 7-36h peak after MI * heart muscle specific markers troponin-T and troponin-I * creatinine kinase (increase by 90% MIs, but less specific as also released from skeletal muscle) * heart specific isoforms of creatinine phosphokinase (CPK-MB) * myoglobin raised early but less specific for heart damage

Answer 219

The troponin complex is a component of the thin filaments in striated muscle complexed to actin. There are three types of troponins: o Troponin T (tropomyosin binding) o Troponin I (inhibits actomyosin ATPase) o Troponin C (calcium binding) The troponins are three different proteins structurally unrelated with each other. Cardiac troponin T and I differ significantly from troponin T and I found in skeletal muscle

Answer 220

Advantages of cardiac troponin: - An index of cardiac damage - Blood levels related to severity of cardiac damage - Predicts major adverse cardiac events such as myocardial infarction

Answer 221

- Coronary artery disease - Chronic hypertension - Cardiomyopathy - Heart valve disease - Arrhythmias – AF, VT - Infective endocarditis - Pulmonary hypertension – PE, COPD - Alcohol and drugs (eg cocaine)

Answer 222

* Shortness of breath * Swelling of feet and legs * Chronic lack of energy * Difficulty sleeping at night due to breathing problems * Swollen or tender abdomen with loss of appetite * Cough with frothy sputum * Increased urination at night * Confusion and/or impaired memory Sensitivity and specificity of signs and symptoms of heart failure is relatively poor

Answer 223

* Initial evaluation of heart failure * Screening for cardiac dysfunction * Guiding management of heart failure * Assessment of prognosis and survival Natiuretic peptides as markers of cardiac damage/overload. An A,B,C of natriuretic peptides

Answer 224

Assays are now available for the active peptides and the N-terminal precursor forms of ANP and BNP. Advantages of N-terminal precursor forms over ANP or BNP - Longer half life - Higher plasma concentrations - Less sensitive to rapid fluctuations

Answer 225

* Congestive heart failure * Aortic stenosis * Dilated cardiomyopathy * Hypertrophic cardiomyopathy * Myocardial infarction * Chronic renal failure

Answer 226

- Haemodynamic - Structural - LVH - Ventricular dilation - Damage/remodelling after MI - Hypoxia/necrosis

Answer 227

* Assessment of severity of congestive heart failure * Screening for mild heart failure * Monitor response to treatment in congestive heart failure * Prognostic outcome/risk stratification

Answer 228

Inflammation - C-reactive protein - Tumour necrosis factor alpha - Interleukins 1, 6, 10 and 18 Oxidative Stress - Oxidised LDL - Myeloperoxidase Extracellular-matrix Remodelling - MMP2, MMP3, MMP9 - TIMP1 - Collagen propeptides - Galectin-3 Neurohormones - Angiotensin II - Aldosterone - Arginine vasopressin - Endothelin-1 Myocyte Injury and Apoptosis - Troponins I and T - Myosin light-chain kinase I - Heart-type fatty-acid binding protein - Creatine kinase MB fraction Myocyte Stress - BNP - NT-proBNP - MR-proANP

Answer 229

- Neuronal and neuromuscular activity - Membrane permeability - Activity of many enzymes The concentration of calcium in ECF is normally kept within closely defined limits

Answer 230

- Parathyroid hormones | - Calcitriol (the active metabolite of vitamin D)

Answer 231

* 1-2kg, 99% mineralized in bone mainly in form of hydroxyapatite * ~1% intracellular,

Answer 232

* Dietary intake: 400-1200mg/day of which ~200mg is absorbed – increased requirement during pregnancy, lactation, growth * Intestinal absorption – in duodenum, stimulated by vitamin D * Calcium exchange in bone: ~99% of body calcium is in bone, ~5g in form that is readily exchangeable * Renal excretion: ~6mmol/day when renal function is normal, PTH increases reabsorption * Plasma: ~50% protein bound (mainly to albumin), ~50% ionized (active form ~1 mmol/L) 1000-12000mg per day. Only a fraction of that is absorbed. About ½ is free [Ca2+] (physiologically active), half protein bound (mainly albumin)

Answer 233

* Net gain of calcium from gut * Recycle through renal tubule multiple times per day * Small net loss of calcium in urine * Bone has a huge reservoir of calcium locked in mineralised form * Remodeling – can either be absorbed in the bone, during resorption the mineralized bone is digested/dissolved

Answer 234

Parathyroid hormone – 84 aa peptide - Secreted by chief cells parathyroid gland. Stimulus for parathyroid hormone secretion is low [Ca++], negative feedback system - If high parathyroid hormone will not be stimulated, will be suppressed - [Ca++] levels monitored by chief cell membrane Ca receptor (GPCR) Target Organs - Kidney: increases calcium reabsorption, decreases phosphate reabsorption, increases synthesis of calcitriol (active form of vitamin D) - Bone: increases bone resorption by increasing osteoclast activity, releasing Ca from mineralised bone (by dissolving/digesting bone) - Increases calcium absorption (indirect action via vitamin D)

Answer 235

• Fat soluble ‘vitamin’ synthesised in skin in response to exposure to UV (‘sunshine vitamin’) • Activated by 2 metabolic steps - 25 hydroxylation in liver to form 25OH D, major circulating metabolite - 1alpha hydroxylation of 25 OH D in kidney produces calcitriol (1alpha,25(OH)2D3), active hormonal metabolite - calcitriol increases intestinal absorption of dietary calcium • it is really a steroid hormone, not a vitamin

Answer 236

There are 32 amino acid peptides. They are secreted by C cells of thyroid. Stimulus for secretion is high [Ca++] Target organs: - kidney: decreases calcium and phosphate reabsorption - bone: decreases bone resorption by inhibiting osteoclast activity - synthetic calcitonin used in treatment of Paget’s disease of bone/osteoporosis

Answer 237

Major causes: - cancer associated eg due to bone metastases - primary hyperparathyroidism Less common causes include: - hyperthyroidism - excessive intake of vitamin D In ambulatory patients = primary hyperparathyroidism (excess PTH) In hospitalised patients = malignancy

Answer 238

Kidney: - renal calcification/stones - increased urine volume (polyuria) Neuromuscular and neurological effects - abdominal pain, constipation - anorexia, nausea, vomiting, mental changes Heart: - cardiac arrhythmias - cardiac arrest

Answer 239

* usually due to a benign adenoma * most common in post-menopausal women * often detected on screening – many patients asymptomatic * ~10% of patients present in clinical evidence of bone disease * 10-20% of patients present with kidney stones Doesn’t lead to overt symptoms

Answer 240

* serum calcium – modest to marked increase * serum phosphate – low or low normal * serum alkaline phosphatase raised in ~20% of cases * serum creatinine may be elevated in longstanding disease (kidney damage) * serum PTH concentration should be interpreted in relation to calcium Calcium and phosphate handling by the kidney tend to be reciprocal. This is a marker of bone remodelling

Answer 241

The most common cause of hypercalcaemia in hospitalised patients is malignant disease. * PTHrP, not quite ectopic source as is slightly different hormone * Do not have to do tests to distinguish between ectopic source and primary hyperparathyroidism * Regulation of delicate balance of osteoclasts and osteoblasts * Anything favouring osteoclast activity over osteoblast hypercalcaemia as bone breakdown leads to more free calcium

Answer 242

• Rehydration/fluid therapy • Inhibition of bone resorption - Bisphosphonates (inhibits OCs) - Calcitonin (inhibits OCs)

Answer 243

* Vitamin D deficiency and disordered vitamin D metabolism (eg renal failure) * Hypoparathyroidism/pseudohypoparathyroidism * Magnesium deficiency (Mg required for PTH secretion and action on target tissues) * Acute pancreatitis ? formation of insoluble calcium salts of fatty acids * Spurious – blood collected into EDTA tube Pseudo = PTH is secreted but problem is with PTH receptor not PTH itself

Answer 244

``` • Numbness • Muscle cramps and spasms • Convulsions • ECG changes • Prolonged hypocalcaemia - Cataracts - Mental disturbances ```

Answer 245

- Bone disease associated with vitamin D deficiency - Rickets – in children, failure of bone mineralisation and disordered cartilage formation - Osteomalacia – in adults, impaired bone mineralisation Rickets occur in childhood, osteomalacia occurs in adulthood

Answer 246

- Adequate supplies of vitamin D3 can be synthesised with sufficient exposure to solar ultraviolet B radiation - Depends on latitude and season - Summer sunlight in cape town – 2500 IU vitamin D3 daily - Melanin, clothing or sunscreens that absorb UVB will reduce cutaneous production of vitamin D3 The balance between sufficient production of vitamin D and avoiding sun damage. Darker skinned people require more vitamin D in general

Answer 247

Synthesis from precursor in skin as well as diet = sources, can make up for one with the other Intermediate undergoes final processing in kidney – inactive or active form. Skin, dietary + metabolic (e.g. converting of intermediate enzyme problems) interruptions can all occur and lead to deficiency

Answer 248

Deficient synthesis and supply of vitamin D - Inadequate intake - Limited sunlight exposure Impaired absorption of vitamin D - Malabsorption syndromes (eg coeliac disease)

Answer 249

- Babies who are bottle fed on non-vitamin supplemented feeds - Children who have little sunlight exposure - Breast fed babies of mothers with marginal vitamin D status

Answer 250

* Muscle weakness * Bowing deformity of long bones * Prominence of the costochondral junction (rachitic rosary) * On x-ray, generalised demineralisation of bone

Answer 251

``` • Diffuse bone pain • Waddling gait, muscle weakness • On x-ray, stress fractures • Serum biochemistry: - Low/normal calcium - Hypophosphataemia - Raised alkaline phosphatase - Secondary hyperparathyroidism ```

Answer 252

Diet vs sunlight as a source of vitamin D: • Limited exposure to UV light leads to vitamin D deficiency • Limited UV exposure is necessary but insufficient in itself to induce the biochemical, radiological and clinical expression of privational osteomalacia • In the presence of limited UV exposure, dietary factors are the major determinants of privational osteomalacia • Major dietary risk factors are low or absent meat intake and high intake of wholemeal cereals

Answer 253

Failure of 25 hydroxylation of vitamin D - Chronic liver disease - Anticonvulsant therapy Failure of 1 hydroxylation of 25 OH-vitamin D - Chronic renal failure - Vitamin D dependent rickets type I Others - Vitamin D resistant rickets - Vitamin D dependent rickets type II

Answer 254

* Hypocalcaemia is common in patients with end stage renal disease – primarily due to decreased synthesis of calcitriol * Hypocalcaemia stimulated PTH secretion (secondary hyperparathyroidism) which also has detrimental effects on the skeleton * Increased [H+] (metabolism acidosis) may increase loss of mineral from bone

Answer 255

• May be congenital or acquired (eg following thyroid surgery, autoimmune disease) • Serum biochemistry - Calcium decreased, phosphate increased, low PTH, alkaline phosphatase normal • May be treated with vitamin D (or an analogue) with or without calcium supplements

Answer 256

- Primary hyperparathyroidism - Vitamin D deficiency - Persistent hypophosphataemia may be observed during intravenous nutrition - Severe hypophosphataemia (0.2-0.3mmol/L) may causes neuromuscular irritability, confusion and hyperventilation

Answer 257

* Paget’s disease of bone (generalised increase in bone turnover) * Osteoporosis * Medullary carcinoma of the thyroid (increased circulating concentrations of calcitonin)

Answer 258

• Aging, especially post menopausal • Endocrine - Premature ovarian failure/hypogonasism - Thyrotoxicosis, Cushing’s, diabetes mellitus • Drugs - Glucocorticoids, alcoholism, prolonged heparin treatment • Others - Immobilisation, malabsorption of calcium, weightlessness (piezoelectricity)

Answer 259

Primary: defect in immune system Secondary: caused by non-immune

Answer 260

• Recurrent infections (normal:

Answer 261

2 or more of the following: • 8 or more new ear infections within 1 year • 2 or more serious sinus infections within 1 year • 2 or more months on antibiotics with little effect • 2 or more pneumonias within 1 year • failure of an infant to gain weight or grow normally • recurrent, keep skin or organ abscesses • persistent thrush (mouth/elsewhere on skin) after age 1 • need for intravenous antibiotics to clear infections • 2 or more deep-seated infections • a family history of primary immunodeficiency

Answer 262

* usually genetic * infrequent but can be life-threatening * adaptive immune system: T and B cells * innate immune system: phagocytes, complement Frequency: 50% antibody, 30% T cell, 18% phagocytes, 2% complement

Answer 263

* x-linked agammaglobulinaemia (Bruton’s disease) * common variable immunodeficiency (CVID) * selective IgA deficiency * IgG2 subclass deficiency

Answer 264

- First described immunodeficiency (1952) - Bruton’s disease - Defect in btk gene (x chromosome) - Encodes Bruton’s tyrosine kinase - Block in B-cell development (stop at pre-B cells) - Recurrent severe bacterial infections Investigations - All Igs absent/very low - B cells absent/low Treatment - IVIg: 200-600mg/kg/month at 2-3 week intervals - Or subcutaneous Ig weekly - Prompt antibiotic therapy (URI/LRI)

Answer 265

* Commonest symptomatic Ab deficiency * Presentation: any age childhood to old age * Peak: early childhood/early adulthood * Recurrent bacterial infections (chest, sinuses) * Autoimmune problems * Usually missed (exclusion diagnosis late diagnosis complications (structural lung/sinus damage) - B cells are normal or low - One or more Igs low - T cells normal; CD4 T cells can be low - Treatment: IVIg; antibiotic prophylaxis

Answer 266

Selective IgA deficiency: - Most common: 1:400-1:800 - Most cases are asymptomatic; some have respiratory infections/diarrhoea Specific Ab deficiency with normal Igs: - HepB vaccination: 5% do not respond - Recurrent bacterial infections (URI/LRI)

Answer 267

Combined Immunodeficiencies: - Severe combined immune deficiency (SCID) Predominant T cell disorders: - DiGeorge Syndrome - Wiskott-Aldrich syndrome - Ataxia-telagiectasia

Answer 268

- Involves both T and B cells - 50% x-linked Presentation - well at birth; problems > 1st month - diarrhoea; weight loss; persistent candidiasis - severe bacterial/viral infections - failure to clear vaccines - unusual infections

Answer 269

- RAG-1/RAG-2 defect no T and B cells - Common cytokine receptor gamma-chain defect (IL-2R) - ADA (adenosine deaminase deficiency) - Bare lymphocyte syndrome (MHC I or MHC II)

Answer 270

- Lymphocyte subsets: T, B, NK (% and numbers) low total lymphocyte count SCID sign! - Pattern: very low/absent T; normal/absent B cells - Igs low - T cell function decreased (proliferation, cytokines)

Answer 271

* Isolation to prevent further infections * Do not give live vaccines * Blood products from CMV-negative donors * IVIg replacement * Treat infections * Bone marrow/stem cell transplant Outcome: • Dependent on promptness of diagnosis • Survival >80% (early diagnosis, good donor match, no infections pre-transplant) • Survival

Answer 272

* 22q11 deletion * complex array of deelopemntal defects * dysmorphic face: cleft palate, low-set ears, fish shaped mouth * hypocalcaemia, cardiac abnormalities * variable immunodeficiency (absent/reduced thymus affects T cell development)

Answer 273

- x linked - defect in WASP (protein involved in actin polymerisation defect in signalling) - thrombocytopaemia, eczema, infections - progressive immunodeficiency - progressive decrease in T cells, decreased T cell proliferation

Answer 274

- AR - Defect in cell cycle checkpoint cells very sensitive to ionising radiation - Progressive cerebellar ataxia - Typical telangiectasia (ear lobes, conjunctivae)

Answer 275

- Quantitative (decreased number) - Qualitative - Chronic granulomatous disease - Chediak-higashi syndrome - Leucocyte adhesion defects (LADs)

Answer 276

- NBT test (nitroblue tetrazolium reduction) | - Flow cytometry assay dihydrorhodamine

Answer 277

Phagocyte defects * Rare genetic disease * Defect in LYST gene (regulates lysosome traffic) * Neutrophils have defective phagocytosis * Repetitive, severe infections Diagnosis: - Decreased number neutrophils - Neutrophils have giant granules

Answer 278

* Defect in beta2-chain integrins (LFA-1, Mac-1) * Delayed umbilical cord separation diagnosis * Skin infections, intestinal and perianal ulcers * Decreased neutrophil chemotaxis * Decreased integrins on phagocytes (flow cytometry)

Answer 279

- Recurrent infections (Neisseia – terminal complex C5, C6, C7, C8 and C9 deficiency) - Severe/fatal pyogenic infections (C3 deficiency) - SLE-like syndrome (C1q, C2, C4, deficiency) - Hereditary angioneurotic edema: failure to inactive complement (deficiency in C1 inhibitor); intermittent acute edema skin/mucosa vomiting, diarhhoea, airway obstruction Investigations: - Complement function: CH50 (haemolysis) - Measure individual components

Answer 280

- Minimise/control infection - Replace defective/absent component of IS - Prompt treatment of infection - Prevention of infection: isolation, antibiotic prophyaxis, vaccination (not live vaccines!) - Nutrition

Answer 281

* Infections: viral, bacterial * Malignancy * Extremes of age * Nutrition * Chronic renal disease * Splenectomy Infections: - Viral: HIV, CMV, EBV, measles, influenza - Chronic bacterial: TB, leprosy - Chronic parasitic: malaria, leishmaniasis Malignancy: - Myeloma - Lymphoma (Hodgkin’s, non-Hodgkin’s) Extremes of Age Prematurity: - Infants

Answer 282

- Reconstruction of full haematopoietic system by transfer of pluripotent stem cells - Used to replace defective, absent, or malignant cells

Answer 283

- SCID - Combined ID (WAS, DiGoerge) - Phagocyte defects - Lymphomas, leukaemias, myeloma

Answer 284

By donor source: • Allogeneic – genotypically matched individuals (sibling, matched unrelated donor (MUD)) • Autologous – patient is the source By site of harvest: • Puncture and aspiration of BM • Peripheral stem cells (CD34+): from the blood • Cord blood stem cells (CD34+): umbilical cord

Answer 285

- Infection (CMV, EBV, adenocirus) - Graft failure (increases with poor matching) - Graft vs host disease (GvHD)

Answer 286

- Transplanted immunocompetent T cells of donor respond against recipient - Acute (rare now improved matching) - Chronic (main causes of death in BMT) - Graft vs tumour (leukaemia) Prevention: - T cell depletion - Immunosuppressive drugs

Answer 287

* Transfer of defective genes into cells * Used in ADA-SCID, X-linked SCID suspended: acute leukaemia I some patients due to insertion of retroviral vector into known oncogenes * Development of self-inactivating lentiviral vectors to reduce risk of insertional mutagenesis (some success for ADA-SCID)

Answer 288

* Congenital (present at birth) | * Inborn (transmitted through the gametes)

Answer 289

* AR * Urine turns black on standing (alkalinisation) * Black ochrontic pigmentation of cartilage and collagenous tissue * Arthritis * (homogentisic acid oxidase def.)

Answer 290

* AR * 1:7,000 * defective transport of cysteine and dibasic aa’s through epithelial cells of renal tubule and intestinal tract * cysteine has low solubility – formation of calculi in renal tract * COLA or COAL * Mutations of SLC3A1 aa transporter gene (Chr 2p) and SLC7A9 (Chr 19)

Answer 291

• Tyrosinase negative - Type 1a – complete lack of enzyme activity due to production of inactive tyrosinase - Type 1b – reduced activity of tyrosinase • Tyrosinase positive - Type II: - AR, biosynthesis of melanin reduced in skin, hair and eyes - Most individuals do acquire a small amount of pigment with age

Answer 292

* Excrete 1-4g pentose sugar L-xylulose daily (reducing sugar) * Benign * Almost exclusively Ashkenazi Jews of Polish-Russian extraction (1:2,500 births)

Answer 293

Beadle and Tatum 1945 (Nobel prize 1958) - All biochemical processes in all organisms are under genetic control - These biochemical processes are resolvable into a series of stepwise reactions - Each biochemical reaction is under the ultimate control of a different single gene - Mutation of a single gene results in an alteration in the ability of the cell to carry out a single primary chemical reaction

Answer 294

Pauling et al 1949, Ingram 1956 - Work on haemoglobin in sickle cell disease - Direct evidence that human gene mutations actually produce an alteration in the primary structure of proteins - Inborn errors of metabolism are caused by mutations in genes which then produce abnormal proteins whose functional activities are altered

Answer 295

- Both parents carry a mutation affecting the same gene - 1 in 4 risk each pregnancy - consanguinity increases risk of autosomal recessive conditions - examples: cystic fibrosis, sickle cell disease

Answer 296

- rare in IEMs | - examples: Huntingdon disease, Marfan’s, familial hypercholesterolaemia

Answer 297

- characterised by carrier females passing on condition to their affected sons - no male to male transmission - female carriers may manifest condition – lyonisation (random inactivation of one fo the x chromosomes) - x-linked dominant: fragile x - x-linked recessive: haemophilia, Fabry’s disease

Answer 298

- two different versions (alleles) of a gene are expressed, and each version makes a slightly different protein. Both alleles influence the genetic trait or determine the characteristics of the genetic condition - example: ABO blood group, alpha1AT

Answer 299

- mitochondrial DNA - inherited exclusively from mother o only the egg contributes mitochondria to the developing embryo o only females can pass on mitochrondrial mutations to their children o fathers do NOT pass these disorders to their daughters or sons - affects both male and female offspring * distribution of affected mitochondria determine presentation * high energy requiring organs more frequently affected * current debate on three parent babies

Answer 300

* inborn errors of metabolism or inherited metabolic disease (IMD) * individually rare (1:10,000 – 1:500,000) * collectively present sizeable problem * important to recognise in sick neonate * screening programmes

Answer 301

* genetic disease individually rare but cumulatively frequent and account for approximately 42% of deaths within the first year of life * they make a significant contribution to the 1% of children of school age with physical handicap and the 0.3% with severe learning difficulties

Answer 302

``` Neonate to adult • neonatal presentation often acute - maple syrup urine disease - tyrosinaemia - OTC (urea cycle defect) • Adult - Wilson’s - Haemochromatosis ``` ``` Neonatal Presentation Often caused by defects in energy metabolism - Amino acid metabolism - Organic acid metabolism - Carbohydrate metabolism - Urea cycle defects - Respiratory chain defects ```

Answer 303

* Condition should be an important health problem * Natural history of the condition should be understood * There should be a recognisable latent or early symptomatic stage * There should be a test that is easy to perform and interpret, acceptable, accurate, reliable, sensitive and specific * There should be an accepted treatment recognised for the disease * Treatment should be more effective if started early * There should be a policy on who should be treated * Diagnosis and treatment should be cost effective * Case-finding should be a continuous process

Answer 304

¥ condition screened for should be an important one ¥ there should be an acceptable treatment for patients with the disease ¥ facilities for diagnosis and treatment should be available ¥ there should be a recognised latent or early symptomatic stage ¥ there should be a suitable test or examination which has few false positives -specificity - and few false negatives - sensitivity ¥ test or examination should be acceptable to the population ¥ cost, including diagnosis and subsequent treatment, should be economically balanced in relation to expenditure on medical care as a whole

Answer 305

``` ¥ Initial National programme Ð PKU Ð Congenital hypothyroidism ¥ Extended to include Ð Cystic fibrosis Ð MCADD Ð Haemoglobinopathies ¥ From 2015, the screening in England expanded to include four additional conditions Ð Maple syrup urine disease (MSUD) Ð Homocystinuria (pyridoxine unresponsive) (HCU) Ð Isovaleric acidaemia (IVA) Ð Glutaric aciduria type 1 (GA1) ```

Answer 306

* Samples should be taken on day 5 (day of birth is day 0) * All four circles on card need to be completely filled with a single drop of blood which soaks through to the back of the Guthrie card

Answer 307

¥ Most are born at term with normal birthweight and no abnormal features ¥ Symptoms frequently in the first week of life when starting full milk feeds ¥ clues for IEMs Ð Consanguinity Ð FH of similar illness in sibs or unexplained deaths Ð Infant who was well at birth but starts to deteriorate for no obvious reason

Answer 308

¥ Full term pregnancy ¥ Symtoms - can be very non-specific Ð Poor feeding, Lethargy, Vomiting, Hypotonia, Fits ¥ or Specific Ð Abnormal smell (sweet, musty, cabbage-like) Ð Cataracts Ð Hyperventilation 2 to metabolic acidosis Ð Hyponatraemia and ambiguous genitalia Ð Neurological dysfunction with respiratory alkalosis

Answer 309

``` ¥ Biochemical abnormalities Ð Hypoglycaemia Ð Hyperammonaemia Ð Unexplained metabolic acidosis / ketoacidosis Ð Lactic acidosis ¥ Clinical Ð Cognitive decline Ð Epileptic encephalopathy Ð Floppy baby Ð Exercise intolerant Ð Cardiomyopathy Ð Dysmorphic features Ð SUDI Ð Fetal hydrops ```

Answer 310

- Blood gas analysis - Blood glucose - Plasma ammonia - Liver function tests - Urinary ketones - Urine reducing substances

Answer 311

``` Ð Plasma & urine amino acids Ð Urinary organic acids Ð Urinary orotic acid Ð Blood acyl carnitines Ð Blood lactate and pyruvate Ð Urinary glycosaminoglycans Ð Plasma very long chain fatty acids ```

Answer 312

``` ¥ Enzymology Ð Red cell galactose-1-phosphate uridyl transferase Ð Lysosomal enzyme screening ¥ Biopsy (muscle, liver) ¥ Fibroblast studies ¥ Complementation studies ¥ Mutation analysis ```

Answer 313

- Classical galactosaemia - Hereditary fructose intolerance - An organic acidaemia - Tyrosinaemia type 1

Answer 314

40-80 mol hydrogen ions in 24 hours which are excreted in urine hydrogen ion concentration of ECF maintained within narrow limits of 36-44nmol/l (pH 7.35-7.45)

Answer 315

25,000 mmol/24 hours CO2 which produce carbonic acid H2CO3 and are normally secreted by the lungs

Answer 316

The kidneys are important in acid base balance as they reabsorb all the filtered bicarbonate and synthesise additional bicarbonate to add to blood. They also produce ammonia which is an important mechanism for H+ excretion and also use phosphate to excrete H+.

Answer 317

In the capillary beds, CO2 produced by tissue respiration diffuses into RBCs and forms carbonic acid (Figure) in the presence of carbonate hydratase. Carbonic acid dissociates to form H+ and bicarbonate HCO3-. H+ are buffered by deoxygenated haemoglobin while HCO3- diffuse outside RBCs in exchange for chloride ions (Cl-) (chloride shift) which maintains electrochemical neutrality. The reverse process happens in the alveolar capillaries and the produced CO2 is excreted into the alveoli.

Answer 318

Hydrogen ion homeostasis depends on buffering in the tissues and blood stream, acid excretion by the kidneys and expiration of carbon dioxide through the lungs. The blood hydrogen ion concentration [H+] is directly proportional to the partial pressure of carbon dioxide (pCO2) and inversely proportional to the concentration of bicarbonate [HCO3-]

Answer 319

pH = pKa + [HCO3-] / pCO2

Answer 320

Results from increased production or decreased removal of hydrogen ions (H+) [other than those that are derived from carbonic acid (or CO2)] or both or due to excessive loss of bicarbonate from the body

Answer 321

♣ Increased acid production in diabetic or alcoholic ketoacidosis, lactic acidosis, poisoning by ethanol, methanol, ethylene glycol (antifreeze) or salicylates, or intake of excess acid (parenteral amino acid administration ♣ Decreased H+ excretion as in renal failure, renal tubular acidosis (type 1 or 4), carbonic anhydrase inhibitors (acetazolamide) ♣ Loss of bicarbonate in diarrhoea, ileostomy, gastrointestinal drainage or fistulae (pancreatic, biliary or intestinal), renal tubular acidosis (type 2)

Answer 322

Excess H+ are buffered by bicarbonate to form carbon dioxide which is lost in expired air. This minimises the rise in H+ concentration (or drop in pH) of the plasma at the expense of a drop in plasma bicarbonate (alkali reserve) H+ + HCO3- HCO3 CO2 + H2O Low plasma bicarbonate concentration is a marker for the presence, and a measure of the severity, of metabolic acidosis

Answer 323

Compensation is effected by hyperventilation which is caused by excess H+ stimulating the respiratory centre. This removes excess CO2 and lowers the excess pCO2 which minimises the increase in H+ [H+ ] = K x pCO2 / [HCO3-] N.B: Respiratory compensation minimises the rise in [H+ ] but does not completely normalise it as it is the elevated [H+ ] that stimulates the hyperventilation

Answer 324

If the cause of acidosis is not corrected, a new steady state is reached with increased [H+], low [HCO3-] and low pCO2 Respiratory compensation is limited if respiratory function is compromised, e.g., COPD, asthma, heart failure If kidney function is normal, excess H+ can be excreted by the kidney, albeit at a slower rate as compared to the very rapid respiratory component of compensation

Answer 325

- Increased [H+] causes hyperventilation, hyperkalaemia with ECG changes, increased adrenaline, decreased myocardial contractility and CNS depression - Increased pCO2 causes peripheral vasodilatation, headache, bounding pulse, papilloedema, flapping tremors, drowsiness and coma

Answer 326

Complete correction of metabolic acidosis is achieved by treating the cause, e.g, insulin and fluids for diabetic ketoacidosis or removal of ethylene glycol in poisoning. In severe conditions with [H+ ] of 100 nmol/l or above, iv bicarbonate (1.26%, 150 mmol/l) is given in small volumes and the effect on arterial [H+ ] regularly checked. Careful monitoring of hyperkalaemia and treatment if necessary using glucose and insulin or dialysis Summary of changes: [H+] elevated (RR 35-46 nmol/l), pH decreased (RR 7.36-7.44), pCO2 decreased (RR 4.5-6 kPa) and [HCO3-] much reduced (RR 22-30 mmol/l)

Answer 327

Is characterised by increased pCO2 , increased [H +], decrease in pH and a compensatory increase in bicarbonates: CO2 + H2O H2CO3 H+ + HCO3-

Answer 328

- Airway obstruction as in chronic obstructive airway disease, bronchitis, emphysema, asthma - Respiratory centre depression as with anaesthesia, morphine, sedatives, cerebral trauma - Neuromuscular diseases: poliomyelitis, motor neurone disease, tetanus, botulism, neurotoxins, Guillain-Barré syndrome - Pulmonary diseases: pneumonia, respiratory distress syndrome, pulmonary fibrosis - Thoracic wall diseases: kyphoscoliosis, flail chest

Answer 329

Respiratory acidosis can be corrected by means that restore pCO2 to normal. If elevated pCO2 persists compensation occurs through increased renal H+ excretion

Answer 330

- Acute respiratory acidosis: [H+] elevated (RR 35-46 nmol/l), pH decreased (RR 7.36-7.44), pCO2 increased (RR 4.5-6 kPa) and [HCO3-] slightly increased (RR 22- 30 mmol/l) - Chronic respiratory acidosis: [H+] slightly elevated or high-normal (RR 35-46 nmol/l), pH slightly decreased or low-normal (RR 7.36-7.44), pCO2 increased (RR 4.5-6 kPa) and [HCO3-] increased (RR 22-30 mmol/l)

Answer 331

Management aims at lowering pCO2 and combating hypoxaemia by improving alveolar ventilation. Bronchodilators, antibiotics, physiotherapy and artificial ventilation are useful. Oxygen at high concentration may be safely used in acute respiratory failure. However, this might be dangerous in chronic respiratory failure as the respiratory centre becomes insensitive to CO2 and hypoxia becomes the main stimulus to respiration.

Answer 332

Is characterised by an increase in extracellular fluid bicarbonate concentration with a consequent reduction in [H+] . Normally, increased plasma bicarbonate leads to incomplete renal tubular reabsorption of bicarbonate and increased excretion in urine.

Answer 333

* ECF volume depletion and hypochloraemia as in gastric aspiration, repeated vomiting with pyloric stenosis, chloride-losing diarrhoea, loop and thiazide diuretics (but not potassium-sparing diuretics). Loss of sodium and water results in the contraction of ECF volume which stimulates renal sodium retention through stimulating renin-angiotensin-aldosterone system and increased excretion of potassium and hydrogen ions. * Alkali intake as in chronic antacid intake, over-treating acidosis * Potassium depletion due to reduced intake, excessive loss, mineralocorticoid excess as in Cushing syndrome, Conn’s syndrome, Barrter’s syndrome, secondary hyperaldosteronism, drugs like carbenoxolone. Potassium depletion and the loss of intracellular potassium results in intracellular shift of H+ This shift causes extracellular alkalosis. Potassium depletion also causes more hydrogen ions to be exchanged (lost in urine) for the reabsorbed sodium ions in the distal convoluted tubules. In addition, potassium depletion stimulates ammonia formation by the kidney and thus increase acid secretion.

Answer 334

decreased [H+] (RR 35-46 nmol/l), increased pH (RR 7.36-7.44), increased pCO2 (RR 4.5-6 kPa) and much increased [HCO3-] (RR 22-30 mmol/l

Answer 335

The expected compensatory change is an increase in pCO2 which would increase the pCO2 / [HCO3-] and thus [H+]. A low arterial blood [H+] inhibits the respiratory centre, causes hypoventilation and an increase in pCO2. However, this mechanism is self –limiting as the increased CO2 stimulates respiration and thus it is mainly useful in acute conditions. In more chronic conditions, the respiratory centre becomes less sensitive to CO2. Should hypoventilation lead to significant hypoxaemia, the low pO2 would be a powerful stimulus of respiration and prevent further compensation

Answer 336

0.9% (w/v) sodium chloride solution (isotonic saline) is used to expand the contracted ECF and correct hypochloraemia. The corrected hypovolaemia will improve renal perfusion and enhance the excretion of excess bicarbonate. In the presence of potassium depletion, correction of the underlying cause and potassium replacement should be initiated

Answer 337

The common feature of this condition is a fall in pCO2 which reduces the ratio of pCO2 to bicarbonate concentration thus reduces [H+].

Answer 338

- Hypoxia and increased respiratory drive as occurs in high altitude, anaemia, pulmonary oedema or pulmonary embolism - Other causes of increased respiratory drive like cerebral trauma, infection or tumours, respiratory stimulants like salicylates, liver failure, septicaemia, primary or voluntary hyperventilation and mechanical ventilation

Answer 339

In acute respiratory alkalosis: decreased [H+] (RR 35-46 nmol/l), increased pH (RR 7.36-7.44), decreased pCO2 (RR 4.5-6 kPa) and a slight decrease in [HCO3-] (RR 22-30 mmol/l). In chronic respiratory alkalosis, slightly decreased or low-normal [H+] (RR 35- 46 nmol/l), slightly increased or high-normal pH (RR 7.36-7.44), decreased pCO2 (RR 4.5-6 kPa) and decreased [HCO3-] (RR 22-30 mmol/l)

Answer 340

treat the underlying cause and increase inspired pCO2

Answer 341

* Water accounts for 60% of body weight in men and 55% in women, 2/3 in intracellular fluid (ICF) and 1/3 in extracellular fluid (ECF), with only 8% in plasma * Water distribution is determined by the osmotic contents of these compartments, which are kept equal, except in the kidney. Changes in solute content of a compartment results in water shift, which restores isotonicity.

Answer 342

* Osmolality of ECF is mainly due to sodium (135mmol/l) and its associated anions chloride and bicarbonate, with glucose and urea also contributing. Osmolality of the ICF is mainly determined by potassium (110 mmol/l) and its associated anions phosphates, proteins and sulphates. * Osmotic effect of plasma proteins (colloid osmotic pressure or oncotic pressure) is important in determining water distribution between these compartments. * Changes in body water content independent of the amount of solute will alter osmolality, which is normally 280-295 mmol/kg of ECF water. Loss of water, as in water deprivation, would increase osmolality and cause water movement from ICF to ECF, thus a slight increase in ECF osmolality occurs. This stimulates thirst centre in the hypothalamus, which promotes a desire to drink, and stimulate the hypothalamic osmoreceptors, which cause the release of ADH (anti-diuretic hormone or vasopressin). This peptide hormone is synthesised in the hypothalamus and transported to the posterior pituitary to be secreted into the blood. It renders renal collecting ducts permeable to water , thus permitting water reabsorption and urine concentration.

Answer 343

• If ECF osmolality falls, there will be no sensation of thirst, vasopressin secretion is inhibited and urine will be dilute, allowing water loss and restoration of normal ECF osmolality. In Diabetes Insipidus, either ADH is not produced by hypothalamus (Cranial DI) or the kidney receptors are resistant to its action (Nephrogenic DI). Very large volume of dilute urine is produced • Vasopressin can also be stimulated by a decrease in plasma or blood volume of 8-10%, even if osmolality is decreased

Answer 344

- Increased ECF osmolality - Severe hypovolaemia - Stress - Pain - Nausea - Exercise - Drugs: nicotine, morphine, sulphonylureas, carbamazepine, clofibrate, vincristine

Answer 345

- Decreased ECF osmolality - Hypervolaemia - Alcohol

Answer 346

The body of an adult man contains about 300mmol of sodium, 70% of it is freely exchangeable and 30% is complexed in bone. ECF sodium concentration is 135-145mmol/l, while ICF sodium is 4-10mmol/l. This gradient is maintained by the activity of the Na+/K+-ATPase, which uses the energy of ATP to pump sodium into the outside of the cells in exchange for potassium, both against their own concentration gradient. Western diet supplies 100-200mmol of sodium in 24h, while the obligatory sodium loss via kidney, skin and guy is less then 10mmol/24h. Excess sodium might contribute to hypertension.

Answer 347

¥ Potassium is the predominant intracellular cation, 90% of body potassium is freely exchangeable, while the rest is bound in RBCs, bone and brain, and only 2% (50-60mmol) is located in ECF. Plasma potassium concentration is not an accurate index of total body potassium and its reference range is 3.0 - 5.5 mmol/l ¥ Potassium tends to diffuse down its concentration gradient from cells into ECF, but this is efficiently opposed by the pumping action of Na+/K+-ATPase, which transports potassium into cells, in exchange for sodium, against concentration gradient.

Answer 348

ECF volume depends upon total body sodium content, since water intake and loss is regulated to maintain a constant ECF osmolality, which in turn depends mainly on sodium concentration. Facing a variable intake, sodium balance is maintained by regulation of its renal excretion. Normally 70% of filtered sodium is actively reabsorbed in the proximal convoluted tubules, with further reabsorption in the Loop of Henle, thus less than 5% of filtered sodium reaches the distal convoluted tubules. Fine control of distal tubule sodium excretion depends on the activity of aldosterone, secreted by adrenal cortex in response to activation of renin-angiotensin aldosterone system.

Answer 349

The fluid flitered by the golmerular capillary filtration membrane is similar to blood plasma, with the exception of proteins, as it is virtually protein free. The hydrostatic pressure within the glomerular capillaries is the major force that drives water and solutes out of blood capillaries and into the Bowman’s capsule. It is opposed by oncotic pressure (due to plasma proteins) of the capillary blood.

Answer 350

In the proximal tubule, 70% of filtered sodium, chloride and water, as well as >90% of potassium, glucose, bicarbonate, calcium, phosphate, amino acids are reabsorbed back to blood, mostly by active transport. Glucose re-absorption has a maximum capacity, called renal threshold. If the amount of filtered glucose exceeds the renal threshold (because blood glucose is higher than 10mmol/l as occurs in diabetes mellitus), not all glucose can be reabsorbed back to blood and glucose will appear in urine.

Answer 351

The loop of Henle and distal and collecting ducts concentrate urine and conserve water under the influence of ADH. They also finely adjust the composition of urine under the influence of aldosterone, which stimulates further sodium reabsorption in exchange for potassium or hydrogen ions. ``` Hydrogen ions (acids) are excreted in the distal tubule, which thus contributes to the regulation of acid-base balance Waste products like creatinine, urea, uric acid and organic acids are excreted through filtration at the glomerulous and secretion by tubules ```

Answer 352

- plasma creatinine and creatinine clearance - blood urea nitrogen - urine analysis

Answer 353

Creatinine is a metabolite of skeletal muscles and is excreted by the kidneys. In renal damage, creatinine concentration in the blood is increased above the upper reference level of 140umol/l. Elevated creatinine level indicates a decreased GFR (glomerular filtration rate). Creatinine clearance is calculated from creatinine level in blood and urine and volume of urine per minute. Monitoring creatinine clearance allows monitoring the progress of kidney disease and response to therapy estimating the time at which dialysis or renal transplantation would be required.

Answer 354

Reflects glomerular filtration and urine concentrating ability. Its level increases as GFR decreases. It also rises in states of dehydration or hypovolaemia as it is reabsorbed back to blood. It is also sensitive to protein intake. The normal reference range in the plasma is 3-7 mmol/l

Answer 355

Physical properties of urine, e.g., colour, aspect, odour, pH, volume, specific gravity; chemical properties as presence of albumin, glucose, acetone, nitrates, as well as microscopic picture e.g., pus cells, red cells, crystals, casts, epithelial cells, parasites ova are useful in diagnosis and management of renal diseases

Answer 356

Secreted by cardiac atria in response to atrial stretch following a rise in atrial pressure. ANP acts directly by inhibiting distal tubular sodium reabsorption and through inhibiting renin-angiotensin-aldosterone system. ANP also antagonises the pressor effects of noradrenaline and angiotensin II and causing vasodilatation.

Answer 357

1. increased loss from the kidneys as in renal disease, diabetes insipidus (DI), diabetes mellitus, diuretics 2. increased loss from skin (sweating), lungs (hyperventilation), gut (diarrhoea or vomiting) 3. decreased intake as in unconsciousness, old age, dementia or infancy

Answer 358

- Thirst - dry mouth - difficult swallowing - weakness - confusion - weight loss - low urine volume (except in DI) Loss of water from ECF increases osmolality and causes movement of water from ICF to ECF, thus moderating the increased osmolality. Thirst centre is stimulated and vasopressin (ADH) secreted. Urine becomes concentrated and of low volume, except in renal disease or DI. Brain dehydration, haemorrhage or oedema may occur.

Answer 359

1. Increased intake as in compulsive water drinking, excessive parenteral fluid, water absorption during bladder irrigation 2. Decreased excretion: renal failure, cortisol deficiency, ectopic ADH secretion (bronchial or prostate carcinoma) or inappropriate ADH secretion (pneumonia, TB, head injury, brain tumours, pain, drugs as chlorpropamide, oxytocin). Clinical picture: Confusion, headache, behavioural disturbances, convulsions, muscle twitching, coma

Answer 360

1. increased intake as in excessive parenteral administration, absorption from saline emetics 2. decreased excretion as in renal failure, primary aldosterone excess as in Cushing’s syndrome, secondary aldosterone excess as in heart failure, liver cirrhosis

Answer 361

- shortness of breath (dyspnoea) - peripheral oedema - venous congestion - hypertension - weight gain - pulmonary oedema These symptoms and signs are due to expansion of ECF volume.

Answer 362

treat the cause, diuretics, control sodium intake

Answer 363

In the kidneys, filtered potassium is almost completely reabsorbed in the proximal tubules. Some active secretion occurs in the most distal part of the distal convoluted tubules, but potassium excretion is mainly a passive process that, together with hydrogen ions, counterbalance the active sodium reabsorption. Aldosterone stimulates potassium excretion directly at the distal tubule, and indirectly by increasing active sodium reabsorption in distal tubules and collecting ducts. Aldosterone secretion from the adrenal cortex is stimulated by renin-angiotensin system and by hyperkalaemia. Both potassium and hydrogen ions can neutralise the membrane potential generated by active sodium reabsorption. In acidosis (a lot of hydrogen ions compete with potassium), potassium excretion decreases and its blood level rises (hyperkalaemia). In alkalosis (low hydrogen ion concentration), potassium excretion increases and its blood level decreases (hypokalaemia). Potassium depletion causes alkalosis.

Answer 364

Potassium is excreted in gastric juice, and much of this, along with dietary potassium, is reabsorbed in the small intestine. In colon and rectum, potassium is secreted in exchange for sodium, partly under the control of aldosterone. Considerable amounts of potassium can be lost in stools in patients with chronic diarrhoea or fistulae, or in patients with persistent vomiting or nasogastric aspiration The cellular uptake of potassium is stimulated by insulin, in exchange for sodium co-transported with glucose. Aggressive insulin treatment of high blood glucose as in non-ketotic hyperglycaemic coma might induce hypokalaemia. Conditions of rapid cell death or membrane damage, as in leukemia, lymphoma or crush accidents cause hyperkalaemia.

Answer 365

Normal dietary intake is 60-200 mmol/24h, prevalent in many foods. Causes of hypokalaemia: 1. decreased intake: parenteral or oral 2. transcellular movement: alkalosis, insulin therapy, rapid cell proliferation, b-adrenergic agonists 3. increased renal excretion as with diuretics, acute renal failure, aldosterone excess, Cushing’s syndrome, liquorice 4. increased extra-renal excretion as in diarrhoea, purgative abuse, rectal adenoma, vomiting, gastric aspiration, entero-cutaneous fistulae, sweating

Answer 366

* Neuromuscular: hypotonia and weakness, constipation, ileus, confusion, depression. * Cardiac: arrhythmia, ECG changes, digoxin toxicity. * Renal: polyuria and polydipsia. * Metabolic: alkalosis

Answer 367

Plasma concentration of 3 mmol/l implies a deficit of 300 mmol, almost entirely from ICF. Replacement should be given with care, particularly when the iv route is used, with a rate of 20 mmol/h, and a total of 140 mmol/24h

Answer 368

1. haemolysed or delayed separation sample 2. increased intake in parenteral infusion, or orally especially with potassium-sparing diuretics, transfusion of stored blood 3. transcellular movement as in tissue damage, catabolic states, insulin lack, acidosis 4. decreased excretion as in renal failure, angiotensin converting enzyme inhibitors, aldosterone deficiency as in Addison’s disease and adrenalectomy

Answer 369

Can kill without warning through ventricular fibrillation and cardiac arrest. ECG changes may precede ventricular fibrillation

Answer 370

* calcium gluconate: 10 ml of 10% solution iv over 1 minute, and repeated as necessary. * iv glucose and insulin * dialysis * restriction of intake * oral ion exchange resin

Answer 371

An inappropriate immune response to non-infectious antigens that results in tissue damage and disease

Answer 372

1 - immediate hypersensitivity 2 - cytotoxic hypersensitivity 3 - serum sickness and Arthurs reaction 4 - delayed-type hypersensitivity, contact dermatitis

Answer 373

- Prick on the skin and then inject the allergen - If the person has mast cells specific IgE to that allergen then they get a local inflammatory response - They get a wheal, with oedema into the extracellular spaces and redness Examples of diseases associated with Type-I Hypersensitivity - Allergen test/skin prick test - Infantile eczema - Asthma - Hayfever

Answer 374

- Swelling of mast cells in tissues - When it becomes systemic it can be life threatening - Anaphylaxis - Epi-pens for this reason

Answer 375

Respond to altered components of human cells - cytotoxic hypersensitivity - due to antigens on surface of cells such as red cells - could be a drug such as penicillin - immune response recognised altered allergen on surface and announces immune response against it - killing of the cells that have encountered it and haemolytic anaemia

Answer 376

- produce IgG | - when exposed to the thing again the cells are killed and degraded

Answer 377

- involved IgG antibodies directed at cell-surface receptors - these antibodies disrupt the normal functions of the receptor by either uncontrollable activation or blocking receptor function - this has been renamed to type V

Answer 378

GRAVES DISEASE: production og autoimmune Ab which stimulates thyroxin receptor uncontrollably, get lots of thyroxin MYASTHENIA GRAVIS: relating to production of autoantibodies which block receptor for Ach causing paralysis as ACh can't stimulate the muscular cells

Answer 379

This relates to rhesus. If the mother is R- and the baby is R+ they can get an immune response against the antigen. If this happens in the first pregnancy there wold be no reaction to the foetus until after birth when the chorion has broken, introducing it to the mother. The second baby gets crossing of the Ab across the placenta and get haemolysis of red cells and can get haemolytic disease of the newborn. This can be prevented by giving an antigen immediately after birth and this will mop up all the foetal red cells preventing the mother becoming sensitised to the antigen.

Answer 380

Specific IgG binds to soluble antigen forming immune complexes in the circulation. Excess of one or another leads to development of immune complexes.

Answer 381

A tetanus booster can cause this – it is a strong local reaction relating to development of Arthurs reaction. * Activate mast cells to release inflammatory mediators * Inflammatory cells invade the site, and blood vessel permeability and blood flow are increased * Platelets also accumulate, leading to occlusion of the small blood vessels, haemorrhage, and the appearance of purpura.

Answer 382

* caused by large intravenous doses of soluble antigens (e.g. drugs) * IgG antibodies produced form small immune complexes with the antigen in excess. * immune complexes deposited in tissues e.g. blood vessel walls. * tissue damage is caused by complement activation and the subsequent inflammatory responses this is an example of T3 hypersensitivity if we inject a large amount of immunoglobulin into the circulation. If it hangs around then we get an immune response against it, and if it is cleared away then we get an immune response at the second injection. Complement is stimulated and we get inflammation. Serum sickness following antivenom - most antivenom created from horses - snake bite get horse protein injected into you and can get serum sickness to that protein in circulation leading to local vasculitis

Answer 383

* type 3 hypersensitivity example * exposed to moulds in hay * sensitisation in lungs development of immune complexes * interstitial pneumonitis Bagazosis – sugar cane reaction

Answer 384

Antigen dose and route of delivery determine the pathology observed in type III hypersensitivity reactions Type of pathology develops following depends on dose and route of exposure. Eg antivenom can get vasculitis, nephritis, arthritis

Answer 385

- first inject antigen to skin - get cells picking up antigen and presenting to TH1 cells - these attract inflammatory cells causing inflammatory reaction Example – Mantoux test - intracutaneous injection of tuberculin - after 2-3 days measure size of reaction - someone exposed/latent TB may have a stronger reaction

Answer 386

shoes or watch could cause a local delayed response. Could be TH2 or TH1

Answer 387

* defined as “disease following a response by the immune system to an otherwise innocuous antigen” * a major health concern around the world * ~40% of the population in Europe have allergies to one or more common environmental allergens This is extremely common with around 40% of those living in Europe having some form of allergy. Worldwide it is a growing problem. Disease follows response by the immune system to an innocuous allergen

Answer 388

* First line of defence against worms * Binds FcεR1 receptor on mast cells * Pre-arms mast cells to react when in the presence of antigen * It binds to high affinity receptors on mast cells and other cell types * Makes it react to an allergen on exposure

Answer 389

* Allergen exposure * Ag presenting cells take it up and present to T cells * Can lead to production of cytokines

Answer 390

``` What causes Allergic Sensitisation? ¥ Exposure to Allergen is critical, this includes: Ð Nature of the allergen Ð Dosage of Allergen (high vs. low) Ð Timing in life eg children vs adults Ð Location of Priming ¥ Role of pro-allergic dendritic cells and cytokines ¥ Genetic predisposition to Allergy ``` Children are more likely to develop allergy than adults in later life

Answer 391

- Effect of birth order and sibship on hay fever and atopy - Reduced prevalence of atopy, asthma and hay fever among children living on farms - Living in a more aseptic environment leading to development of allergy? - Having older siblings makes you less likely to have allergy? They go to school and bring back the allergens? - Children on farms protected against allergy – wide variety of pathogens etc that programmes immune response to be more regulatory and less vulnerable to allergens

Answer 392

¥ Common allergens Ð House dust mite, pollens, cockroach etc ¥ Allergens are named systematically: Ð After the source organism and the order they were discovered Ð e.g. Der p1 comes from Dermatophagoides pteronyssinus Ð Not all proteins are allergenic ¥ One possibility is the allergens have common functionality Ð Der p1 is a protease ¥ Allergens are normally received in small doses Ð 1mg per year of ragweed pollen may be enough to sensitise ¥ High dose exposure (eg Fel d 1) may lead to tolerance They tend to be proteins but there are no specific characteristics that define an antigen

Answer 393

- Filaggrin links skin integrity and allergy - When it is defective atopic dermatitis is greater - This is due to the access for allergens

Answer 394

Not known but one candidate protein is TSLP. This may switch DC to a ‘pro-allergic’ state.

Answer 395

- Primed for allergic response when first exposed to allergen - Ig lines surface of mast cells - When exposed again get immediate hypersensitivity response - Cross links leading to degranulation and the release of cytokines and various other inflammatory mediators

Answer 396

- Mast cell activation requires cross linking on surface on mast cells - Particular allergen - Only that one can unlink them on the surface of mast cells

Answer 397

- Not just immediate response – early response - Also late phase response comes afterwards - Immediate hypersensitivity response - Delayed response after several hours – late phase response - Charaterised by recruitment of cells such as T cells, eosinophils - Activation of those cells in the tissues leads to a more prolonged allergic response

Answer 398

- primary allergen response - allergen presented by antigen representing cells eg dendritic cells to cells and can get production of IgE – important in lining surface of mast cells for 2nd exposure - Aggregation of cells types and activation I the tissues causes late phase response on 2nd exposure on recruitment of other cell types

Answer 399

HISTAMINE: increases vascular permeability, causes smooth muscle contraction LEUKOTRIENES: increases vascular permeability, cause smooth muscle contraction, stimulates mucus secretion PROSTAGLANDINS: chemoattractants for T cells, eosinophils and basophils

Answer 400

CYTOKINES IL-4, IL-13: promotes Th2, promotes IgE TNF-alpha: promotes tissue inflammation

Answer 401

- increased fluid secretion, increased peristalsis | - expulsion of GI tract contents (diarrhoea and vomiting)

Answer 402

- decreased diameter, increased mucus secretion - congestion and blockage of airways (wheezing, coughing, phlegm) - swelling and mucus secretion in nasal passages

Answer 403

- increased blood flow, increased permeability - increased fluid in tissues causing increased flow of lymph to lymph nodes, increased cells and protein in tissues - increased effector response in tissues

Answer 404

located in the tissues recruited to the sites of allergic reactions express FceRI upon activation

Answer 405

1. Release highly toxic granule proteins and free radicals upon activation to kill microorganisms/parasites and cause tissue damage in allergic reactions. 2. Synthesise and release prostaglandins, leukotrienes and cytokines in order to amplify the inflammatory response by activating epithelial cells and recruiting leukocytes.

Answer 406

¥ Late-phase reaction is dependent on allergen dose ¥ Continued synthesis and release of inflammatory mediators ¥ Chronic allergic inflammation caused by Th2 cells i.e. a type IV hypersensitivity reaction The second phase of allergic response is T cell mediated ¥ Mostly consisting of allergen specific Th2 cells ¥ These cells recruit other cells by cytokine release ¥ Potentiate further responses

Answer 407

¥ There is a key difference between sensitisation to allergen and reaction to allergen. ¥ Individuals must be sensitised to an allergen before they can react. ¥ Sensitisation requires presentation of allergen to T cells by DC and the priming of Cognate B cells to produce IgE ¥ The Reaction to allergen occurs when the individual is re-exposed to allergen and it binds preformed IgE on mast cells

Answer 408

``` ¥ “A State of reversible bronchial hyper-reactivity resulting from a persistent inflammatory process in response to a number of stimuli in a genetically susceptible individual”. ¥ Atopic and Non-Atopic Ð Non Atopic includes ¥ Occupational ¥ Exercise induced ¥ Nocturnal Asthma ¥ Post-bronchiolitic Wheeze ```

Answer 409

``` • episodes of wheezy breathing • narrowing of the airways • rapid changes in airway • obstruction • reaction times and severity vary slight wheeziness to asthma • attack • common allergens causing • asthma include - pollen - HDM - plants - some foods ```

Answer 410

- occurs within seconds of allergen exposure - results in airway obstruction and breathing difficulties - caused by allergen-induced mast cell degranulation in the submucosa of the airways

Answer 411

- chronic inflammation of the airways - caused by activation of eosinophils, neutrophils, T cells and other leukocytes - mediators released by these cells cause airway remodelling, permanent narrowing of the airways, and further tissue damage

Answer 412

contraction and mucus contribute to blocking the airway.

Answer 413

Blockage of effector pathways: • inhibit effects of mediators on specific receptors anti-histamine (block the histamine H1 receptor) • inhibit mast cell degranulation non-steroidal anti-inflammatory (e.g. chromoglycate) • inhibit synthesis of specific mediators lipoxygenase inhibitors - Steroids – Act directly on DNA to increase transcription of anti-inflammatory mediators (e.g. IL-10) and decrease transcription of pro-inflammatory mediators - Bronchodilators – Reverse acute effect of allergy on airways - Immunotherapy – Reverses the sensitisation to allergen by means of tolerising exposure Preventing allergy is the gold of allergy research. There are promising studies of food allergies.

Answer 414

- Graves disease – TSH receptors in thyroid - Type 1 diabetes – insulin producing cells of the pancreas - Graves opthalmopathy, fibroblasts in the eye may express TSH leading to inflammation. - Autoimmune disease against tsh receptors, causes hyperthyroisism – graves - Agonistic antibody against TSHR- hyperthyroidism - T1 diabetes – get T cell destruction

Answer 415

- Ankylosing spondylitis, undifferentiated spondyloarthropathy, reactive arthritis, psoriatic arthritis, urethritis, iritis - Spectrum of severity and HLA B27 association - Associated with bowel inflammation HLA B27 – molecule involved in the attachment of antigens to molecules. It is associated with a number of diseases.

Answer 416

- Multisystem disease - Characterised by autoantibodies to nuclear antigens eg double stranded DNA - Relapse and remission

Answer 417

- alopecia - discoid lesions - mucus membrane ulceration - raynauds phenomenon - proteinuria - anemia, leukopenia - butterfly rash - pericarditis - arthritis - anti-nuclear bodies

Answer 418

The immune system has various regulatory controls to prevent it from attacking self proteins and cells. Failure of these controls will result in immune attack of host components – known as autoimmunity.

Answer 419

Immune system does not attack self proteins or cells – it is tolerant to them.

Answer 420

¥ Central tolerance – destroy self-reactive T or B cells before they enter the circulation ¥ Peripheral tolerance – destroy or control any self reactive T or B cells which do enter the circulation

Answer 421

If immature B cells in the bone marrow encounter antigens in a form which can crosslink their IgM, apoptosis is triggered. Stromal cells in the bone marrow which B cells encounter before going out – then they die.

Answer 422

T cells recognise antigens that are presented to them by MHC proteins. - Thymus cells - Have to go through the thymus after bone marrow - Doesn’t just recognise a large protein, recognises part of it; a peptide - Recognises it in the context of MHC proteins T cells need to be able to recognise foreign peptides that are bound to self-MHC - Binds to peptide and the MHC molecule itself - CD8 binds to side of MHC - In CD4 binds in similar way but different - CD4 binds to side of MHCclass II molecules

Answer 423

need to select for T cell receptors which are capable of binding self MHC. BUT - If binding to self MHC is too weak, may not be enough to allow signalling when binding to MHC with foreign peptides bound in groove. - If binding to self MHC is too strong, may allow signalling irrespective of whether self for foreign peptide is bound in groove.

Answer 424

Is it useless? Doesn’t bind to any self-MHC at all Death by neglect Is it dangerous? Binds self MHC too strongly Apoptosis triggered – negative selection Is it useful? Binds self MHC weakly Signal to survive – positive selection

Answer 425

A specialised transcription factor allows thymic expression of genes that are expressed in peripheral tissues.

Answer 426

- Promotes self tolerance by allowing the thymic expression of genes from other tissues - Mutations in AIRE result in multi-organ autoimmunity

Answer 427

B cells and autoimmune IgM, no T cell help and so no class switch.

Answer 428

- antigen may be present in too low a concentration to reach the threshold for T cell receptor triggering - immunologically privileged sites e.g. eye, brain

Answer 429

- Naïve T cells need costimulatory signals in order to become activated - Most cells lack costimulatory proteins and MHC class II - If a naïve T cell sees its MHC/peptide ligand without appropriate costimulatory protein it becomes anergic – ie less likely to be stimulated in future even if co-stimuation is then present

Answer 430

A subset of helper T cells known as Treg (T regulatory cells) inhibit other T cells. - Treg express transcription factor FOXP3 - Mutation in FOXP3 leads to severe and fatal autoimmune disorder – Immune dysregulation, Polyendocrinopathy, Enteropathy X-linked (IPEX) syndrome

Answer 431

- Each copy of chromosome 6 carries 3 different MHC class I and 3 different MHC class II genes - High levels f genetic variation (polymorphism) - MHC is associated with more disease than other region of the genome

Answer 432

- SLE is >10 times more common in females than males - MS is approximately 10 times more common in females than males - Diabetes is equally common in females and males - Ankylosing spondylitis is approximately 3 times more common in males than females This shows there is an endocrine factor predisposing one gender over the other.

Answer 433

- Hygiene hypothesis: NOD mice and SPF conditions. Migration and T1D, MS and SLE - Smoking and rheumatoid arthritis – 13 pairs of identical twins where 1 of each pair smoked and 1 of each pair had RA, in 12/13 cases the twin with RA was the smoker SPF = specific pathogen free

Answer 434

- Loss of/problem with regulatory cells - Release of sequestrated antigen - Modification of self - Molecular mimicry

Answer 435

Modification of self... - Citrillin is an amino acid, not coded for by DNA - Arginine can be converted to citrulline as a post-translational modification by peptidylarginine deiminase (PAD) enzymes - Citrullination may be increased by inflammation - Autoantibodies to citrullinated proteins seen in rheumatoid arthritis. Now used for clinical diagnosis.

Answer 436

- Disease is triggered by infection with Streptococcus pyogenes - Antibodies to strep cell wall antigens may crossreact with cardiac muscle

Answer 437

GRAVES DISEASE - Auto-antibodies bind Thyroid stimulating hormone (TSH) receptor and stimulate it, resulting in hyperthyroidism - Disease can be transferred with IgG antibodies MYASTHENIA GRAVIS - Autoantibodies bind to acetylcholine receptor and block the ability of acetyl choline to bind - Also lead to receptor internalisation and degradation - Results in muscle weakness IMMUNE COMPLEXES IN SLE AND VASCULITIS - Autoantibodies to soluble antigens form immune complexes - Deposited in tissue eg blood vessels, joints, renal glomerulus - Can lead to activation of complement and phagocytic cells - Immune complexes depositing in kidney can lead to renal failure

Answer 438

IgG is the only antibody small enough to get across the placenta. - Patient with Graves disease makes anti-TSHR antibodies - Transfer of antibodies across placenta into foetus - Newborn infant also suffers from graves disease - Plasmapheresis removed maternal anti-TSHR antibodies and cures the disease

Answer 439

- Direct killing by CD8+ CTL - Self-destruction induced by cytokines such as TNFalpha - Recruitment and activation of macrophages leading to bystander tissue destruction - Multiple sclerosis - Insulin dependent diabetes mellitus

Answer 440

- Th17 cells are helper T cells that produce the cytokine IL-17 - Implicated in autoimmune diseases including spondyloarthropathy, MS and diabetes - Highly inflammatory - Produce cytokines which are involved in the recruitment, migration and activation of immune cells

Answer 441

- Anti-inflammatories: NSAID, corticosteroids - T cell depletion (RA: anti-CD4, anti-CD20) - Therapeutic antibodies (nti-TNF; anti-VLA-4 (blocks adhesion)) - Antigen specific therapies, indevelopemnt. Glaritamer acetate, increases T-regs

Answer 442

Donor and recipients are genetically identical, do not usually generate any immunological problems. Skin transplant is an example of an autologous transplant in humans

Answer 443

This is between genetically identical twins

Answer 444

Donors and recipients are from the same species but are genetically different. This is a more common type of transplant. Eg from one mouse to another non-genetically identical mouse or between non-identical humans such as siblings

Answer 445

Donor and recipient are different species. In humans the best animla transplant source are pigs, cows or maybe baboons. Problems include the introductions of xenosis which is an infectious disease from animal and mismatch in MHC

Answer 446

* Histocompatibility = tissue compatibility * Immune responses to transplant are caused by genetic differences between the donor and the recipient * The most important are differences between the major histocompatibility antigens * Human transplants largely unsuccessful until identification of human MHC in 1967 * In 1968 WHO nomenclature committee designated that human MHC proteins be names HLA (Human Leukocyte Antigen)

Answer 447

* Described as MHC restrictive * Refers to the need for MHC to present antigens to T cells * The antibody on the B cell can bind to the antigen irrespective of any other proteins * MHC can only interact with TCR as part of MHC complex

Answer 448

T cells recognise short peptide fragments that are presented to them by major histocompatibility (MHC) proteins. All our somatic cells have HLA class I. Proteins within the cell are degraded and loaded onto MHC.

Answer 449

* These are similar except MHC class II only present on the surface of WBC * They are not present in somatic cells that are not part of the immune system * They get their peptides to present in a different way * Will engulf a dying or dead cell * Will process the peptides particularly the MHC and will present on HLA to CD4 T cells

Answer 450

Helper T cells are required to produce antibody and cytotoxic T cell responses. HELPER T CELLS - information and support for other immune cells via cytokine production CYTOTOXIC T CELLS - highly specific killer cells

Answer 451

In transplants, both the MHC protein and the peptide in its binding groove may be foreign In transplants the MHC itself and the thing being presented can both be foreign. This is why it is so important to match HLA in the donor and the recipient. This make it more likely to be successful.

Answer 452

Usually we try to match 4/6 MHC class II loci, reduces likelihood of future transplants and problems with future transplants. Clinicians try to match as many class II as passible. With an increasing number of mismatches get increasing amount of time going to be accepted by the host

Answer 453

* Recipients will have a history of disease which will have resulted in a degree of inflammation * Organs from deceased donors are also likely to be in inflamed conditions due to ischaemia * Transplant success is less sensitive to MHC mismatch for live donors - Lots of inflammation aids in activation of t cells can can make it more likely the host immune system will break tolerance/direct an immune response against transplant - From deceased donor more likely to be inflamed, also doesn’t help as this will cause the WBC in the organ to have an activated phenotype - Not only the recipient immune system present – donor immune system in transplanted organ!

Answer 454

- hyperacute rejection - acute rejection - chronic rejection

Answer 455

¥ Within a few hours of transplant – very rapid ¥ Most commonly seen for highly vascularised organs (e.g. kidney) ¥ Requires pre-existing antibodies, usually to ABO blood group antigens or MHC-I proteins ¥ (ABO antigens are expressed on endothelial cells of blood vessels) ¥ Antibodies to MHC can arise from pregnancy, blood transfusion or previous transplants ¥ Due to strong Ab response ¥ Usually because the recipient has seen the antigen (ABO or MHC) before in pregnancy or transfusion or another transplantation ¥ Not dissimilar to vaccination ¥ Immune system trying to reject transplanted tissue

Answer 456

Recognition of Fc region leading to… - Complement activation - Antibody dependent cellular cytotoxicity (Fc receptors on NK cells) - Phagocytosis (Fc receptors on macrophages) FAB region: hypervariable region responsible for binding the Ag Fc: constant region that can be identified by complement pathway – serious for proteins that can opsonize the target cell

Answer 457

* Antibodies bind to endothelial cells * Complement fixation * Accumulation of innate immune cells * Endothelial damage, platelets accumulate, thrombi develop * Eg kidney transplantation

Answer 458

Inflammation results in activation of organs resident dendritic cells. T cell response develops as a result of MHC mismatch. Based upon the immune system within donor transplant – activated phenotype

Answer 459

the recipient immune system can protect the MHC and TCR will bind to MHC and will identify them as foreign/non-self

Answer 460

Inflammation results in activation or organ’s resident dendritic cells. DC migrate to secondary lymphoid tissue where they encounter circulating effector T cells. Macrophages and CTL increase inflammation and destroy transplant. In this case eg kidney (last slides notes), the dendritic cells in the tissues WBC and get a kidney and all the cells come with it eg dendritic cells and macrophages. DCs migrate and activate T cell immunity and will move from kidney into recipients lymph nodes. T cells there will identify DCs. The immune system doesn’t recognize the DCs from donor. The T cells will then hunt down the cells in the donor kidney and destroy it. - kidney graft with dendritic cells - dendritic cells migrate to the spleen where they activate effector T cells - effector T cells migrate to graft via blood - graft destroyed by effector T cells

Answer 461

¥ Can occur months or years after transplant ¥ Blood vessel walls thickened, lumina narrowed – loss of blood supply ¥ Correlates with presence of antibodies to MHC-I This can occur even under immunosuppressant therapy. Antibodies bind to the endothelial cells and recruit immune effector cells, particularly cells of the inert immune system. This causes damage to the endothelial cells apoptosis and internalized by cells of the recipient. The recipient antigen presenting cells internalizes the donor cells and start to process the donor MHC molecules. This is another case of MHC mismatch. Chronic rejection is when the donor cells die and are taken up by DCs. The foreign MHC is cut up unto peptides and presented to HLC class II. They are foreign to the immune system activating T cells to destroy the transplanted tissue.

Answer 462

¥ Donor-derived cells die ¥ Membrane fragments containing donor MHC are taken up by host DC ¥ Donor MHC is presented into peptides which are presented by host MHC ¥ T cell response is generated Acute – donor WBC, host immune system detects MHC on those donor WBCs Chronic – host DCs internalize donor cells and present MHC peptides to T cells (it is the peptide that is foreign) – this is indirect recognition

Answer 463

¥ Previously called bone marrow transplant, now renamed as source is often blood ¥ Often autologous – transfer of biological material from one part of a person, to another part ¥ Until 1980 only HLA identical siblings could be used as donors due to the risk of rejection or graft versus host disease Stem cells are more often derived from peripheral blood now than bone marrow. It is a better way of getting more cells and it is easier. HSCs can find their way to bone marrow after infusion and regenerate there. They can be cryopreserved with little damage.

Answer 464

¥ When transplanted tissue is immune cells themselves, there is the risk of donor immune cells attacking the host – GVHD ¥ Can be lethal – best approach is prevention ¥ Removing T cells from transplant reduces GVHD In this case the graft is attacking host instead of the other way round. If we remove the T cells from the recipient so wont be attacked, or from HST’s transplanted so no initial attack. Prevent GCHD using immunotherapy. This can be beneficial….

Answer 465

¥ But sometimes mismatch and donor leukocytes can be benificial - removing original leukemia ¥ Graft versus leukemia response ¥ Development of GVL may prevent disease relapse Patient could have residual leukemia, chemo may not have completely removed the leukemic cells, so new immune system sees leukocytes as foreign and will attack them, preventing patient leukemia reoccurring.

Answer 466

¥ Essential to maintain non-autologous transplant ¥ Immunosuppressants for transplant can be - Ð General immune inhibitors (e.g. corticosteroids) Ð Cytotoxic – kill proliferating lymphocytes (e.g. mycophenolic acid, cyclophosphamide, methotrexate) Ð Inhibit T cell activation (cyclosporin, tacrolimus, rapamycin) • Immunosuppressives may need to be maintained indefinitely Maintenance phase of immunosuppression to last potentially their whole life. If things go wrong then there can be a rescue phase – more powerful immunosuppressants

Answer 467

- Breakthrough drug for transplant - Blocks T cell proliferation and differentiation - Next generation therapies less toxic and effective at lower doses - Very toxic – making newer versions

Answer 468

1. Steroids – eg prednisolone 2. Cytotoxic – eg mycophenolate motefil 3. Immunosuppressive specific for T cells – eg cyclosporine A, FK506 The best combination is being worked out and this is important for treating individuals

Answer 469

¥ There is currently no immunosuppressive that will prevent transplant rejection whilst maintaining other immune responses ¥ Transplant patients more susceptible to infection and malignancy Ð Immediate risk e.g. CMV ¥ Immunosuppressive drug toxicity can lead to organ failure eg cyclosporin nephrotoxicity in kidney transplant The immune system is not meant to be inhibited indefinitely so can cause all sorts of problems. People on immunosuppressive therapy at greater risk of cancer. Also drug toxicity which can result in organ failure. New and better immunosuppressive therapy is vital to improving patients outcomes after transplantation

Answer 470

1 - Haematopoietic stem cell 2 - common myeloid progenitor --> neutrophils, red cells, platelets etc OR 2.1 - common lymphoid progenitor 3. T cell precursors and B cell precursors 4 - B cell precursors go on to become immature B cells

Answer 471

- usually non specific symptoms of bone marrow suppression | - symptoms of organ infiltration more often in advanced disease

Answer 472

- commonest leukaemia in children 40 y.o

Answer 473

- bone marrow morphology; infiltration by undifferentiated blast cells - immunophenotyping; B-cell surface markers (or T markers for T-ALL), light chain restriction, TdT positive - cytogenetics

Answer 474

Chemotherapy in children >90% cure adults have a much lower survival because different cell or origin, different oncogene mutations, older patients do not tolerate intensive treatment

Answer 475

PRESENTATION: enlarged lymph nodes EPIDEMIOLOGY: peak incense in young adults, possible association with Epstein Barr Virus (EBV) aka HHV4 HISTOPATHOLOGY: presence of large Reed-Sternberg cells is pathognomonic, these are malignant B-cells, but typically 99% of cells are reactive non-malignant cells

Answer 476

chemotherapy +/- radiotherapy - 5 year survival ~50-90% depending on age, stage and histology - especially good results in young adults

Answer 477

- low grade - high grade - T-cell lymphomas - EBV (HHV4) driven lymphomas in immunosuppressed patients

Answer 478

* Many lymphomas carry chromosome translocations involving the Ig heavy chain or light chain loci * Ig genes are highly expressed in B-cells * Each Ig gene has a powerful tissue specific enhancer near to the constant (C) segment * Most cases of follicular lymphoma carry t(14;18)(q32;31) * This juxtaposes the BCL-2 gene on chromosome 18 with the IgH locus on chromosome 14 * Causes overexpression of BCL-2 protein * BCL-2 is an apoptosis inhibitor * Some cases of high grade lymphoma carry t(8;14)(q24;q32) * This juxtaposes the MYC gene on chromosome 18 with the IgH locus on chromosome 14 * MYC is a powerful oncogene * Can also get MYC or BCL-2 translocations to one of the Ig light chain loci

Answer 479

Presentation: enlarged lymph node(s) Histology - Normal tissue architecture partially preserved - Normal cell of origin recognisable  used to name lymphoma – follicular lymphoma, mantle cell lymphoma etc

Answer 480

- Histology - Immunocytochemistry - Cytogenetics - Light chain restriction - PCR  for clonal Ig gene rearrangement, for chromosome translocations (eg t(14;18) IgL Bcl-2)

Answer 481

Treatment - Chemotherapy - Glucocorticoids (eg prednisolone) - Radiotherapy - Monoclonal Ab therapy – rituximab (anti-CD20) Prognosis - Relatively indolent - Respond well to therapy - But hard to cure

Answer 482

Presentation: enlarged lymph node(s) Histology - Loss of normal tissue architecture - Normal cell of origin hard to determine

Answer 483

- Histology - Immunocytochemistry - Cytogenetics - Light chain restriction - PCR  for clonal Ig gene rearrangement, for chromosome translocations

Answer 484

Treatment - Chemotherapy - Glucocorticoids - Radiotherapy - Monoclonal Ab therapy  rituximab – anti CD20 Prognosis - Variable depending on type, stage and other factors - Overall long term survival

Answer 485

``` • Rare • Usually CD4 cells • Often present with skin infiltration eg - Sezary syndrome - Mycosis fungoides ```

Answer 486

* Found in Japan, Caribbean and UK citizens of Caribbean origin * Associated with retrovirus HTLV-1 (human T-cell leukaemia/lymphoma virus 1) infection

Answer 487

* EBV or Human Herpes Virus 4 (HHV4) directly transforms B-lymphocytes in culture * Due to viral oncogene LMP-1 * Over half of all normal individuals carry latent EBV infection * Do not develop lymphomas due to effective immune surveillance by cytotoxic T-cells

Answer 488

- The endogenous latent EBV may transform B-cells - No longer eliminated by cytotoxic T-cells - Develop high grade lymphoma Transplant patients on cyclosporine - Lymphoma usually regresses on withdrawal of immunosuppression - But patient may lose the graft AIDS patient - Lymphoma may regress on successful HAART

Answer 489

Presentation - Most often as incidental finding on fbc - Persistent infection(s); due to immunosuppression, low IgG, suppression of normal B cells - Lymph node enlargement - Symptoms of bone marrow suppression Epidemiology - 85% of cases >50yo

Answer 490

- FBC: lymphocytosis - Immunophenotyping: cell surface markers, light chain restriction - Cytogenetics

Answer 491

Presence of a single monoclonal Ig in the serum

Answer 492

Malignant Multiple myeloma – high levels of paraprotein Benign Monoclonal gammopathy of undetermined significance (MGUS) – low levels of paraprotein. Low levels of paraprotein occasionally seen in lymphoma or chronic lymphocytic leukaemia. IgM paraprotein seen in waldenstrom’s macroglobulinaemia. * Monoclonal gammopathy of undetermined significance (MGUS) – low levels of paraprotein. * Low levels of paraprotein occasionally seen in lymphoma or chronic lymphocytic leukaemia. * IgM paraprotein seen in waldenstrom’s macroglobulinaemia.

Answer 493

1. Suppression of normal bone marrow, blood cell and immune cell function 2. Bone resorption and release of calcium 3. Pathological effects of the paraprotein

Answer 494

- Anaemia - Recurrent infections - Bleeding endency

Answer 495

- Myeloma cells produce cytokines (esp. IL-6) - Which stimulate bone marrow stromal cells to release the cytokine RANKL - Which activates osteoclasts: lytic lesions of bone, bone pain, fractures - Calcium released form bone causes hypercalcaemia: multiple symptoms including mental disturbance

Answer 496

- Precipitates in kidney tubules cause renal failure - Deposited as amyloid in many tissues - 2% of cases develop hyperviscosity syndrome: increased viscosity of blood leading to, stroke, heart failure

Answer 497

- serum electrophoresis for paraprotein - urine electrophoresis: Bence-Jones protein represents free monoclonal light chains - increased plasma cells in bone marrow - ESR (very high due to rouleaux formation) - Radiological investigation of skeleton for lytic lesion

Answer 498

Chemotherapy (not curative) - Cutotoxic drugs - Glucocorticoids - Thalidomide analogues - Bortezomib Allogeneic bone marrow transplant - Only available for a small number of younger patients (

Answer 499

The leukaemias are a group of diseases characterised by malignant overproduction of white blood cells or their immature precursors.

Answer 500

• Varies between types of leukaemia • But typically first presents with symptoms due to loss of normal blood cell production - Commonest presentation is abnormal bruising (suppression of platelet production) - Or repeated/abnormal infection (suppression of neutrophil production) - Sometimes just anaemia (suppression of RBC production)

Answer 501

There are a few rare forms that don’t fit. • Lymphoid- involving cells of the lymphocyte lineages – commonly B-cell, – more rarely T-cell • Myeloid- involving any of the non-lymphocyte blood cell lineages – commonly neutrophils or their precursors – But can be erythroid, platelet, basophil lineages etc

Answer 502

ACUTE: undifferentiated leukaemia, characterised by immature white cells (blast cells) CHRONIC: differentiated leukaemia, characterised by mature WBCs

Answer 503

• Activation of oncogenes and inactivation of tumour suppressor genes • May involve genes similar to other malignancies eg - RAS - MYC - P45 – tumour suppressor gene • But also some specific to the leukaemias • Chromosome translocations to generate novel hybrid oncogenes eg - BCR-ABL in CML - PML-RARA in AML M4 - And many others Numerical and chromosome changes eg - Monosomy: loss of normal genes, tumour suppressor genes - Trisomy: gene amplification

Answer 504

All the malignant cells derive from a single mutant stem cell

Answer 505

Radiation - acute radiation accidents - atomic bomb survivors Chemicals - eg industrial exposure to benzene Chemotherapy - cancer chemotherapy with alkylating agents (eg busulphan) generates a future risk of leukaemia Age - the age related incidence is different in different types of leukaemia Controversial - electric power lines - nuclear power stations - natural background radiation Most cases are not associated with any identifiable precipitating cause

Answer 506

• Chemotherapy with cytotoxic drugs • Stem cell and bone marrow transplant (SCBMT) • Disease specific agents - Including oncogene targeted drugs - Combination of drugs used to kill leukaemic cells - Optimised for type and subtype of leukaemia - Cytotoxic drugs mostly target dividing cells

Answer 507

Kills normally dividing cells - GI epithelium  nausea and diarrhoea - Hair follicles  hair loss - Loss of fertility - Haemopoietic progenitors  bone marrow suppression Haemopoiesis is reconstituted form the quiescent stem cell pool.

Answer 508

* Give intense chemotherapy and totally body irradditation * Wipe out leukaemic cells AND normal stem cells * Reconstitute bone marrow by transplanted stem cells

Answer 509

- Shortage of HLA (MHC) matched donors | - High mortality of the procedure for older or sicker patients

Answer 510

- bone marrow smear - all look like lymphoblasts - very suspiscious Large numbers of myeloid blasts (AML) or lymphoblasts (ALL) in bone marrow – therefore “undifferentiated leukaemias’.

Answer 511

Typical symptoms due to bone marrow suppression - Thrombocytopenia  purpura (bruising), epistaxis (nosebleed), bleeding from gums - Neutropenia  recurrent infections - Anaemia  lassitude, weakness, shortness of breath

Answer 512

Peripheral blood - Presence of blasts - Cytopenias Bone marrow aspirate - >30% blasts is diagnostic of acute leukaemia Shortage of normal cells – cytopenia

Answer 513

If the cells don’t mature the blast cell pool will build up and up without stopping and wont die. There is a high turnover so they are being made very quickly. Many of the chromosome translocations in acute leukaemias - involve genes for transcription factors - which control cell differentiation Chromosome abnormalities also help determie prognosis and response to treatment.

Answer 514

French-American-British (FAB) classification - based on stage of differentiation arrest eg. AML M4 promyelocytic leukaemia - and predominant cell type eg AML M6 erythroleukaemia (M0-M8) Also some rare leukaemias that don’t fit the main classifications. WHO classification - similar to FAB, but - acute leukaemias with specific chromosome translocations are classified separately - eg AML with a translocation between chromosomes 8 and 21

Answer 515

* chemotherapy * combinations of drugs * optimised for each type and sub-type of acute leukaemia * ALL- add chemo- or radio-therapy to CNS ALL to CNS – BBB means in cytotoxic drugs don’t get to the cells and so brain may be a site where leukemic cells survive and can come back from. Phase 1: remission induction  blast with chemotherapy, may get very ill and wipe out most of the blasts Phase 2: consolidation therapy – to kill residual leukaemic stem cells  if leave at previous stage leukaemia may come back so send home with less powerful chemo agents oral for the next year and less likely to relapse.

Answer 516

Childhood ALL - >90% long term remission/cure Adult ALL – poorer prognosis because disease is different - Different cell of origin - Different oncogene mutations AML - >80% long term remission in young adults with aggressive treatment Elderly unable to tolerate aggressive chemotherapy or SCMBT The elderly you know may relapse because you can’t give really aggressive chemotherapy. Some may choose not to have chemo as it’s a horrible experience for just a few extra months of life.

Answer 517

“Differentiated leukaemias” – increased numbers of differentiated cells From patient with CLL. Too man WBC here and all are lymphocytes.

Answer 518

- Large numbers of mature (clonal) lymphocytes in bone marrow and peripheral blood - Therefore also called chronic lymphocytic leukaemia

Answer 519

- Recurrent infections – due to neutropenia, and suppression of normal lymphocyte function - Anaemia - Thrombocytopenia - Lymph node enlargement - Hepatosplenomegaly

Answer 520

- Controlled by regular chemotherapy to reduce cell numbers - A few patients may die in 12 years As this is a disease of the elderly a lot of the time, then surviving of more than 12 years you are likely to die of something else first. These days many people live with cancer, rather than die of it.

Answer 521

“differentiated leukaemias” Increased numbers of differentiated cells. * CML * Far too many WBC of neutrophil lineage * Lots of mature cells but also immature cells * Doesn’t mean all the cells are differentiated and mature, but that they are not all arrested earlier on

Answer 522

Symptoms - Anaemia - Night fever/night sweats - Splenomegaly Infection is not a major symptom of CLL, because not short of neutrophils even though they’re not all working properly.

Answer 523

* Very high white count (neutrophilia) * Left shift in blood and bone marrow * Presence of Philadelphia chromosome * BCR-ABL gene rearrangement

Answer 524

Controlled but not cured by chemotherapy. - Cytotoxic drugs - Interferon alpha – body normally makes interferons when you have a viral infection. If you give someone interferon alpha it makes them feel like they have the flu. - Imatinib Course - Survival on treatment usually measured in years – 4-5 years - But eventually progresses to accelerated phase and then blast crisis Treatment - Allogenic bone marrow or stem cell transplant curative - Autologous transplant sometimes tried - Most patients >50 years old. Do not tolerate transplant. Transplant only really used for younger and fitter patients

Answer 525

resembles an acute leukaemia, but very refractory to treatment

Answer 526

95% of cases of CML have a detectable Philadelphia chromosome (Ph') * Breakpoint on chr22 in middle of BCR gene * Breakpoint in chr9 in middle of ABL gene * after translocation get a gene with a bit of BCR and a bit of ABL – a chimaeric gene Breakpoints occur within introns. - The ABL protein is a protein tyrosine kinase - But activity is tightly regulated - BCR-ABL protein has constitutive (unregulated) protein tyrosine kinase activity * Tyrosine kinases involved in cell signalling * ABL not cell surface protein but important signalling protien in cell * Tightly regulated * Most of the time not active and only stimulated when theres a need * BCR-ABL protein still has the catalytic domain but not regulated – active all the time independent of regulation * This causes problems

Answer 527

- Proliferation of progenitor cells in the absence of growth factors - Decreased apoptosis - Decreased adhesion to bone marrow stroma

Answer 528

Inhibiton of BCR-ABL tyrosine kinase causes apoptosis of CML cells. Cells undergo apoptosis. Entered clinical trials 1999. Approved by NICE 2003. This was very quick to be approved – notmally it takes >10 years. There was a large drive from patients etc that pushed it through to be approved. Compared to previous treatments Imatinib - Remission is induced in more patients - With greater durability - And fewer side effects But some patients become drug resistant

Answer 529

Current trials - Patients in long term remission taken off therapy - But closely monitored by RT-PCR In some cases the disease comes back. If the patient is put back on imatinib they will respond. Some patients a long time after will have no sign of relapse – so sometimes it is possibly a cure!!

Answer 530

Commensal non pathogen (in host) Zoonotic non pathogen (in carrier) commensal opportunist (in host)

Answer 531

- in host - present but not capable of causing disease in the host - eg e.coli

Answer 532

- in carrier - present but only capable of causing disease in another host - eg e.coli O157

Answer 533

- in host - present and capable of causing disease in host but only in certain circumstances - eg bacteroides fragilis

Answer 534

a microbe capable of causing a specific degree of host damage

Answer 535

* Sterile sites must be free fro contamination eg skin flora in blood cultures * Non sterile sites require decontamination of normal flora eg faeces, mouth, skin * Samples with high volume or relatively low infected pathogen load require concentration (centrifugation, filtering) eg CSF, ascites, 24 hr urine

Answer 536

1 - take culture 2 - PREPARATION PHASE enrichment, purification, amplification 3 - IDENTIFICATION PHASE molecular DNA/RNA, gross morphology (microscopy), chemical composition (HPLC MassSpec)

Answer 537

1- take sample 2 - PREPARATION PHASE concentration, sample treatment 3 - IDENTIFICATION PHASE molecular DNA/RNA, gross morphology (microscopy), chemical composition (HPLC MassSpec)

Answer 538

- easy to perform - rapid screening - some parasites have specific morphology - specific immunofluorescence staining possible

Answer 539

- not sensitive - screening sputum smears requires at least 10,000 orgs per ml to be visualised - general stains are not specific - labour intensive (expensive) - requires specialist interpretive expertise (more expensive)

Answer 540

this relies on the ability of the test system to be able to grow the pathogen

Answer 541

- non selective media e.g. blood agar - semi selective media eg MacConkey agar - selective growth temperatures e.g. campylobacter species

Answer 542

- aerobic culture - microaerophilic culture - anaerobic culture

Answer 543

42^C | 10% CO2

Answer 544

- colony morphology, colour, haemolysis - colony count - colony identification - systematic identification - colony resistance to antibiotics

Answer 545

where you put antibiotics on a plate and see where the bacteria will grow - if it grows near the drug then it is resistance. Can also be done for dosages.

Answer 546

1 - culture requires permissive cell lines cytopathic effect immunofluorescnet staining of culture 2 - direct antigen detection eg influenza virus

Answer 547

- Electron microscopy can see this virus but not identify it as ‘swine flu’ - Culture takes 3-10 days - Rapid ELISA for fluA antigen = 15 mins - ELISA for flu antibody

Answer 548

- Cheap, simple, reliable reagents - Sensitive – eg single organisms can be grown and identified - Validated specificity eg ‘gold standards’ with multiple parameters - Direct in vivo measurement of effectiveness of therapy eg antibiotic sensitivity - Easily archived eg epidemiology

Answer 549

- Some pathogens cannot be grown eg mycobacterium leprae - Some pathogens cannot be well differentiated by biochemistry alone - Slow: culture requires at least over night incubation, viral: 3-10 days, mycobacterial: 6-12 weeks - Some pathogens grow too slowly to aid rapid diagnosis eg mycobacterium tuberculosis - Labour intensive (expensive) - Requires specialist interpretive expertise (more expensive)

Answer 550

- Constitutive - Virulence - Antibiotic resistane - Pathogenic phenotype - Repetitive

Answer 551

Specificity If the test unique to the genus/species/type? Reliability Is the target nonessential/transmissible? ``` Sensitivity How many organisms does it take to suggest disease? - For every sample type - For every host type - For every epidemiological niche ``` Accuracy Do we need to detect live organisms? Is the detection system susceptible to genomic shifts/mutations? Rapidity Is the result generated going to be beneficial to the paitent? Instant bedside? – diagnosis of paediatric meningitis Same day? – transmission/quarantine Next day? – antibiotic resistance Next week? – chronic persistent infections

Answer 552

microarrays * Ordered short oligonucleotide probes (40-70mer) attached to slides in defined spots * Each spot represents a single gene * Comparative genomic hybridisation (CGH) used mostly for DNA

Answer 553

- Covers the whole genome - Strand dependent - Can be used for RNA and transcriptomics - Can look for microRNA

Answer 554

Aim to detect a gene or gene products that are pathogen specific. Single gene target (PCR) – PCR, qPCR Multiple gene target (microarray) – microarray Mass spectrometry (MALDI-TOF)

Answer 555

Mass spectrometry MALDI-TOF (matrix assisted laser desorption ionisation-time-of-flight) Compare against an archival database, 62,500 unique spectral profiles identifying 1,160 species and 233 genera.

Answer 556

Looking for selected genes or gene products that drive the disease process. - Latex agglutination test - Uses particles coated with specific antibody to cell wall antigens - CSF direct agglutination test - Neisseria meningitides Group B - Haemophilus influenza type b - Streptococcus pneumonia type 3 Specific cell wall antigens are predictive of invasiveness and virulence.

Answer 557

1. Enterohaemolysis 2. Agglutination with anti-toxin antibodies 3. PCR for the presence of the gene

Answer 558

- Good specificity - Good sensitivity - Easily automated

Answer 559

- Serological response is not rapid therefore not useful in acute infections - Single sera results are meaningless due to possible previous exposure - Some antibodies are cross-reactive - Virulence is only INFERRED by the presence of a biomarker ONLY in vivo testing of cultured pathogen infected into an animal model can prove virulence.

Answer 560

Sequencing can show differences between SINGLE bases in strains or resistance mutations to antibiotics

Answer 561

- Rapid - Faster detection of pathogens that traditional techniques - Allows appropriate, timely antimicrobial therapy and infection control interventions - Increased sensitivity over culture and microscopy based techniques in POSITIVE samples - Can be automated and has potential for Point of Care testing

Answer 562

- Expensive - Does not screen for UNKNOWNS - Requires expertise - Labour intensive - Possibility of contamination - Require complex and efficient methods for extraction of nucleic acid - NEGATIVE samples may STILL need Gold Standard culture. Hospitalisation costs accounted for 95% of health-system costs among patients suspected of tuberculosis. In culture-negative patients, PCR tests do not significantly decrease time to TB exclusion

Answer 563

following the host transcriptomic profile with microarrays

Answer 564

- bio-signature profiling - metabolic profiling - rapid intrinsic fluorescence - rapid point of care testing - lab on a chip

Answer 565

- Point of care (POC) testing - Lab on a chip - Nanotechnology - Microfluidics - Rapid sequencing of samples direct at the bedside… - DNA extraction, PCR and sequencing on site

Answer 566

- But who will do the analysis? - Where? - How will the testing be controlled? - Who will interpret the results? - When does the science become medicine?

Answer 567

We can use a polyclonal mixture of antibodies that will bind to various epitopes. These are presented when challenged with an antigen. In this example there are two epitopes. When they are injected into the mouse we get an immune response, one B cell with a particular receptor will bind to an epitope, and the other will bind to the other epitope. They will both then proliferate to make antibodies for those epitopes.

Answer 568

Monoclonal antibody technology was developed in 1975. A mouse is injected with an antigen. B cells are then isolated form the mouse after it has developed an immune response and these are fused using chemicals with myeloma cells from a B cell tumour. We get a mixrue of cells (some original B cells, some myeloma cells and some hybridoma cells). We select the hybridoma cells on HAT medium. The medium stops myeloma cells being able to grow, B cells are not immortal so die quickly, and this means that in the medium the only cells that can survive and grow are the hybridoma cells. When we have this population of hybridoma cells we can dilute them out to individual cells which then divide to clonus cells. Each will secrete an antibody with the same specificity which bind to one type of epitope. They are monoclonal antibodies. * Hybridomas can be stored indefinitely and grown to produce monoclonal antibody when required * Antibody genes can be cloned from the hybridomas which allows antibodies to be engineered for different applications * Polyclonal or monoclonal antibodies can be produced which bind to Fc regions of particular antibody classes eg to IgG’s, IgA’s etc. These ae called anti-isotypic antibodies.

Answer 569

* Originally radioactive – radioimmunoassay (RIA) * Commonly now enzyme eg horseradish peroxidase, alkaline phosphatase (usually detected by coloured product) – enzyme linked immunosorbent assay (ELISA) * Other alternatives are luminescent One antibody is labelled. Used to be radioactive but as radioactivity is dangerous we now use enzymes. When you give these enzymes to substrates a coloured product will be produced which is measured. The alternative is illuminescence.

Answer 570

Direct • Often used to quantify an antibody Capture or switch • Often used to quantify an antigen Using these assays, the concentration of analyte (antibody or antigen) in the sample can be calculated by comparison to analyte standards of known concentration.

Answer 571

* Antigen immobilised on solid support * Test antibody solution added, incubated and non-bound removed by washing * Bound antibody detected by incubation with labelled 2nd antibody (ie anti-immunoglobulin) and non-bound removed by washing Uses: - Screen hybridoma supernatants - Detect exposure to infectious agent Second Ab is the detecting Ab. This has a label bound to it. The mixture is then washed and we add a substrate for the enzyme. We then measure the colour formed and correlate it’s intensity to the amount of Ag formed on the plate. We can look for HIV in the blood using this assay.

Answer 572

* Antigens mat be present in low concentration. Because antibodies have high affinity for antigen this technique can concentrate the antigen. * Need tow antibodies reacting with different epitopes on the antigen * One antibody immobilised on solid support * Test antigen solution added, incubated and non-bound removed by washing * Bound antigen detected by incubation with the other antibody, which has been labelled and non-bound removed by washing. We coat the antigen with antibody. This can be low in concentration. The body has a high affinity for Ag and can concentrate it – we need two Abs to bind to different epitopes. One is immobilised on a solid support. We add solution containing Ag to detect – this will bind to the antibody. We wash the mixture to remove any non-bound antigen. The second antigen is linked to the enzyme. We add the substrate an get a colour formed from the product again.

Answer 573

We can measure cytokine secretion from T cells. We coat the bottom of the well with antibody that binds specific cytokine. We add activated T cells which are secreting cytokines. Once secreted, they will bind specifically with antibody in wells. They are captured by those antibodies and we wash off the cells and the second labelled antibody is added. We then add the enzyme and detect the colour formation as before.

Answer 574

1. Can be used to detect antigens or antibodies 2. Used to measure size of the protein being analysed 3. Can be sued to calculate protein concentration 4. May show is protein has been degraded

Answer 575

SDS-PAGE is often combined with western blotting. This can be use to measure the size of a protein or for antibody/antigen detection. We can calculate the concentration of the protein we are looking at. We can also demonstrate whether the protein has been degraded in anyway. We start with a mixture of antibodies. We take the mixture, mix it with SDS and boil it up. SDS will bind to the protein and give a negative charge. We load this onto a gel and run it in an electric current. Proteins are negatively charged and will migrate to the positively charged electrode. We take the gel and stain it with something that binds to the protein. This shows us that it is a mixture of proteins generally, but it would be better if we could specifically identify what we are interested in so we can do a western blot. We transfer this to nitrocellular paper by an electric current. We then add antibodies specific to the antigen to detect. Then we take the nitrocellulose blot paper and incubate it with a substrate of enzyme. We get a single band corresponding to the protein we are trying to detect. At the same time, we run protein standards in the gel. * SDS PAGE/Western blotting often used alongside ELISA * In WB, protein concentration can be measured by comparing intensity of band we are detecting to band from a protein standard of known concentration * If protein is degraded it mat be more useful to use WB to calculate protein concentration, as some of degradation fragments mat contribute to signal in ELISA if both coating and detecting antibody are bale to bind to them.

Answer 576

antibody coated magnetic beads. Purification of immune cell subsets. Couple them to particles that are paramagnetic. We then take the Abs and they will bind specifically to particular lymphocytes because WBCs have certain proteins on their surface. We then pour them onto an iron wall mesh and apply a magnetic field. The Ab bound to cells will bind to iron mesh, and cells not bound to Ab are washed out. Then we stop applying the magnetic field and elute the cells to get a population of a particular kind of cell. Used to purify particular subset base don protein it has on its cell surface.

Answer 577

* Individual cells within a mixed population are tagged by treatment with monoclonal antibodies which bind to surface molecules and are labelled with fluorescent dyes * Mixed cells are then forced through a nozzle to form stream of single cells * Individual cells pass through a laser beam which scatters light and causes dye to fluoresce and provides information on bound antibody and cell surface protein * A cell sorter can separate specific subpopulations of cells Fluorochromes fluoresce when a light is shone on them in different colours. When we combine cells from a mixed population with monoclonal antibodies they bind to a particular marker on the protein. They are then forced through a nozzle converting the mixture into a single stream of cells. We pass that laser through the stream and get scattering which gives us information about the cell. When the laser hits a fluorochrome will fluoresce in certain colours. This is measured by a computer giving information about the mixture of cells which is then plotted on a dot plot. Each spot corresponds to a single cell and gives information about the particular fluorescence. Going up both the x and y axis corresponds to increasing fluorescence. This shows that it is a fixed population of B cells. Some don’t fluoresce at all – showing they are potentially not B cells but T cells instead. Part will fluoresce heavily for M and D (both on surface), some more for D and some more for M. We can combine this with FACS and this means when the cells pass through the single stream we can pick up cells fluorescing one way or another. We can isolate a particular population of cells and make the machine just do cells of D or M for example.

Answer 578

* Blood serum * Blood cells * Urine * Synovial fluid * Saliva * Mucus * Cerebrospinal fluid

Answer 579

* Transplant compatibility * Immunodeficiency * Autoimmunity allergy * Malignancy

Answer 580

* In humans known as HLA (Human Leucocyte Antigens) * The MHC is located on chromosome 6 and contains 3 MHC class I proteins and 3 MHC class II proteins * Highly polymorphic – 100s of different variants

Answer 581

¥ Lymphocyte subset estimations are performed using monoclonal antibodies to: CD3, CD4 and CD8 on whole blood and analysed by flow cytometry ¥ The percentages of cells in each subset is determined using a FACS machine ¥ The results are reported as percentages and absolute counts

Answer 582

MHC-peptide complexes made which bind specifically to the T cell receptor of appropriate MHC-peptide specific T cells. A fluorochrome e.g. phycoerythrin added and visualisation is by flow cytometry. By creating MHC complexes loaded with HIV antigen we can calculate for example what proportion of CD 8+ T cells will bind to the antigen. Immunodeficiency – analysing cell function

Answer 583

¥ Neutrophils are found in acutely inflamed tissue ¥ Ingest pathogens and kill using reactive oxygen species ¥ Rapidly die after phagocytosis which generates pus ¥ Deficiency in neutrophil numbers – neutropenia – high rate of infection ¥ Deficiency in phagocyte function; chronic granulomatous disease – patients cannot form reactive oxygen species, succumb to bacterial and fungal infections

Answer 584

neutrophil oxidative burst assay This test is based on the principle that nonfluorescent DHR (dihydrorhodamine) 123 when phagocytosed by normal activated neutrophils (after stimulation with PMA – phorbol myristate acetate) can be oxidized by reactive oxygen species (ROS), produced during the activated neutrophil respiratory oxidative burst, to rhodamine 123, a green fluorescent compound, which can be detected by flow cytometry.

Answer 585

• Nephelometry: an automated and rapid method used to measure serum immunoglobulin levels; it relies on the light-scattering properties of antigen-antibody complexes Nephelometry measures light refraction - Often used to study the amount of antibody from different classes present in serum eg IgG, IgA etc - Here, serum is mixed with anti-isotope antibodies. We shine a light onto complexes and the light will be scattered. We can measure the scattering with a machine and this will give an idea about the amount of antigen present We can study the amount of antibody in different populations. We can mix the serum with different antibodies which will bind specifically to IgG or IgA

Answer 586

- IgE responses predominate | - Common allergens: house dust mites, cat, dog, trees, grasses, moulds, egg, milk, cod, soya, peanut, etc

Answer 587

Skin Prick Test: In allergic individual, IgE binds to allergen and via the Fc region of the antibody binds to receptors on mast cells. This causes mast cells to degranulate causing the release of mediators (e.g histamine) which causes reddening and swelling of skin Degranulation of mast cells results in release of mediators eg histamine causing reddening and raised skin. ¥ RAST (RadioAllergoSorbent Test) The suspected allergen is bound to an insoluble material and the patient's serum is added. If the serum contains antibodies to the allergen, those antibodies will bind to the allergen. Radiolabeled anti-human IgE antibody is added where it binds to those IgE antibodies already bound to the insoluble material. The amount of radioactivity is proportional to the serum IgE for the allergen ¥ Often fluorescence is used instead of radioactivity e.g. ImmunoCap Take suspected allergen and bind to solid face. Take serum from patient and add to antigen. If there are Abs specific to the antigen in the serum, it will bind. Ag that are specific bind to IgE and will be radiolabelled. We can detect the amount of radioactivity. Radioactivity is dangerous and so we are replacing it with fluorescence (immunoCap).

Answer 588

¥ Autoimmune disease characterised by autoantibodies to nuclear antigens eg DNA, RNA ¥ Detection of autoantibodies is useful for diagnosis and monitoring disease activity e.g. Systemic Lupus Erythematous (SLE) Autoimmune disease characterised by production of autoantibodies causing a range of symptoms, often dermatological

Answer 589

¥ ELISA (Quantitative) and immunofluorescence (Qualitative) ¥ Performed in parallel to increase sensitivity ¥ Immunofluorescence: serum added to human cell line. Then probed with fluorochrome-labelled anti-immunoglobulin antibody. Visualised by fluorescence microscopy ¥ 98% of SLE patients are Anti-nuclear antibody positive,

Answer 590

¥ Intravenous immunoglobulin (IVIG) is a blood product purified from the serum of between 1000-15,000 people/batch ¥ Used to treat patients with antibody deficiencies at 200-400mg/Kg/3 weeks ¥ At high dose 2g/kg/4 weeks used as an immunomodulatory agent in a number of immune and inflammatory disorders ¥ Used in neurology, haematology, immunology, nephrology, rheumatology and dermatology ¥ Other example: rabies: after a bite from a suspected rabid animal, polyclonal antibodies isolated from the serum of individuals who have been immunised with the rabies vaccine injected into the wound site – Human Rabies Immunoglobulin (HRIG) Deficiencies – given the Ab IV at low doses Immunomodulatory ages at higher doses

Answer 591

¥ Approx. 45 monoclonal antibodies are licensed to treat disease: cancer, chronic inflammatory diseases, transplantation, infectious diseases and cardiovascular medicine ¥ Monoclonal antibodies can have their effects either by binding and blocking a process or by mediating immune responses such as initiation of complement or antibody-dependent cell mediated cytotoxicity (ADCC) ¥ Molecules such as toxins or radionuclides can be joined to monoclonal antibodies: antibody binds to cancer cell which is then killed by toxin or radioactivity

Answer 592

One way of action is to bind to something an block the process, or alternatively to mediate processes such as the complement pathway. The two processes are shown above; left Ab bound to Ag on a pathogen, by binding it initiates the complement pathway leading to killing of the pathogen. This is called the classical pathway but there are several that have evolved in initiating complement. The right picture shows initiating cytotoxicity (?) bound to pathogen, binds to Fc receptor on surface of immune cell and stimulates NK cell and when activated goes on to kill the pathogen by inducing pathogen to undergo apoptosis. Can take these Abs and attach various molecules to them eg. toxins or radioisotopes. This can be used to kill cancer cells. This will target the protein produced on surface of cancer cells. Binds to the surface protein on cancer cell and the toxin or radioactivity kills the cancer cell.

Answer 593

A resolved measure (diversity) of differences (variables) that determines: a. Disease distribution in time and place b. Disease transmission c. Disease manifestation d. Disease progression

Answer 594

Confirming outbreaks • Inside institutions - Did patient A catch this pathogen from patient B? - Do patients A, B and C from the same hospital ward have the same strain? • In the community - Who was the index case and what is the likely source? • In the past - What has driven the geographical spread of important strains? • In the lab - Is this an outbreak or a contaminant?

Answer 595

• Shifts in virulence - Is the incidence of annual infections increased from… last year? - Are drug resistance strains on the rise? From where? • Reservoirs of infection - New infection or recrudescence? It is important to know how quickly the mutations occur and are fixed. We also need to know if these patients are newly infected patients, or recrudescence where it is latent for years and suddenly comes back.

Answer 596

- Presence or absence – biochemical test, presence of O157 antigen, presence of verotoxin - Addictive weighting – combination of single tests

Answer 597

combination of single tests

Answer 598

Genomic factors - Factoral – presence or absence of a gene base/s change in genome/gene relative to location in the genome - Functional – type of substitution (synonymous/non-synonymous) - Temporal – mutation rate (time since the last alteration)

Answer 599

Spoligotyping dendrogram showing relatedness of pattern We can use maths to define how different one strain is from another. Strains are all different. We can produce an evolutional tree of he patterns of change between the strains and see the differences between them. We can track back via the tree to find the original strain, and the length of the line tells us how different it is from the other.

Answer 600

mutations that are intragenic (between genes) or synonymous (not altering coding

Answer 601

substitutions causing coding to be altered

Answer 602

deletions or insertions (disrupting coding frame), creation of STOP codons (truncation), corruption of STOP codons (elongation), corruption of CONTROL sequences (eg promoters)

Answer 603

when the DNA changes – want to predict this and we can measure it easily

Answer 604

not so easy to predict, the DNA has caused the protein to change, DNA changes into something functional

Answer 605

• Replication rate: a high division rate provides a higher mutation rate • DNA or RNA polymerase proof reading fidelity: some species (eg HIV) have low fidelity promoting high mutation rate • Selection pressure from the host or environment: high selection pressure removes ‘weak’ mutants and emphasises clusters, loss of selection pressure allows deletions • Degree of redundancy in the genome: multiple copies of a single gene in the genome allow for mutations in one copy without compromising overall functionality, movement or recombination within genome may not effect phenotype Transmission rate: high transmission rates relative to the mutation rate results in dissemination and single strain outbreaks Some things divide slowly so huge changes and mutations; others divide really slowly. Some hosts are not susceptible to pathogens. But this doesn’t mean that the organism can’t grow in the host – they can be infected just not affected

Answer 606

Restriction fragment length polymorphism (RFLP) Stage 1 Cut genome with low frequency cut restriction enzyme Stage 2 Separate fragments on a gel and visualise with a probe against repetitive element Result is a profile of the number of SNPs at each locus

Answer 607

a. Transmission: hospital acquired infection b. Reservoirs of infection: contact tracing c. Spread or emergence of resistance

Answer 608

These are resistant to every drug – MDR TB is coming! It is currently mainly in Russia but is being brought into the UK.

Answer 609

Molecular epidemiology offers a variety of methods to test questions involving disease transmission, strain virulence, pathogen evolution. Choosing the most appropriate system requires: 1. Knowing the most appropriate variable/s 2. Quantitating variations and deriving diversity 3. Generating identities or clusters 4. Applying related data - Geographic location - Time of isolation - Incidence - Prevalence - Transmission rate - Severity of disease