Clinical sciences Flashcards
What is the relative risk reduction?
Relative risk reduction (RRR) or relative risk increase (RRI) is calculated by dividing the absolute risk change by the control event rate
What is the process by which atherosclerosis occurs?
Endothelial dysfunction is triggered e.g. by smoking, HTN and hyperglycaemia
Results in changes to the endothelium
Fatty infiltration of the sub-endothelial space by low-density lipoproteins (LDL)
Monocytes migrate from the blood and become macrophages. These macrophages then phagocytose the LDL and turn into large ‘foam cells’ (fat laden macrophages). As these macrophages die the result can further propagate the inflammatory process
SM proliferation + migration from the tunica media into the intima results in formation of a fibrous capsule covering the fatty plaque
Result of C3 deficiency?
causes recurrent bacterial infections
Results of C5 deficiency?
predisposes to Leiner disease
recurrent diarrhoea, wasting and seborrhoeic dermatitis
Results of C5-9 deficiency?
encodes the membrane attack complex (MAC)
particularly prone to Neisseria meningitidis infection
The MAC essentially punches holes in the surface of the cell. When the happens enough times, the cell is killed. So without these complement subunits this cannot happen.
Results of C1, C2 and C4 deficiency?
Form part of the classical complement pathway. A deficiency in any of these complements makes patients susceptible to immune complex diseases including SLE
What to give alongside ferrous fumarate in iron deficiency and why?
Ascorbic acid (vit C) - think about being told to drink orange juice
Iron is best absorbed in the small intestine in the ferrous form (Fe2+). Ferric iron (Fe3+), however, is more difficult for the intestinal mucosa to absorb. By the addition of Ascorbic acid (vitamin C) to oral iron therapy, there is increased conversion of Fe3+ to Fe2+ in the gastrointestinal tract. This increases the proportion of Fe2+ iron, which is more readily absorbed, thus improving the response to treatment.
Where is iron absorbed?
upper small intestine especially the duodenum
How is iron transported around the body?
carried in plasma as Fe3+ bound to transferrin
What decreases the absorption of iron?
A more alkaline environment: PPIs, gastric achlorhydria (no gastric acid)
tetracycline
tannin (found in tea)
Which type of renal stones form in acid/alkaline urine?
Acid - uric acid
Alkaline - struvite
Struvite = magnesium ammonium phosphate (ammonia is alkaline)
What is the inheritance pattern and cause go homocystinuria?
Homocystinuria is a rare autosomal recessive disease caused by a deficiency of cystathionine beta synthase
What are the features of patients with homocystinuria?
Everything points downwards, looking at legs
Fine, fair hair - pointing to the floor Arachnodactylyl - hands hanging by sides Learning difficulties - LOW IQ DOWNWARDS dislocation of the lens Increased risk of VTEs (DVT in leg)
Investigations in homocystinuria?
increased homocysteine levels in serum and urine
cyanide-nitroprusside test: also positive in cystinuria
Treatment of homocystinuria?
vitamin B6 (pyridoxine) supplements
(Google image for pictures)
B6 is needed in the conversion of homocysteine -> cysteine. Therefore providing more should clear the body of more homocysteine.
What are the stages of the cell cycle and what regulates it?
Regulated by cyclins
G0: resting phase
G1: cells increase in size, under influence of p53, this stage determines cell cycle length
S: synthesis of DNA, RNA, histone, centrosome duplication
G2: cells continue to increase in size
M: mitosis, cell division (shortest phase)
What is the inheritance pattern of mitochondrial diseases?
none of the children of an affected male will inherit the disease
all of the children of an affected female will inherit the disease
inheritance is only via the maternal line as the sperm contributes no cytoplasm to the zygote
What might you see on a muscle biopsy in mitochondrial diseases?
muscle biopsy classically shows ‘red, ragged fibres’ due to increased number of mitochondria
What foods contain folic acid?
Liver, green vegetables and nuts
Which conditions are associated with collagen type 1, 3, 4 and 5?
1 = Osteogenesis imperfecta 3 = Vascular variant of Ehlers-Danlos syndrome 4 = Goodpastures, alports 5 = Classical variant of Ehler-Danlos syndrome
What are the different sleep stages?
N1 → N2 → N3 → REM
Non-REM stage 1: Light sleep, associated with hypnic jerks
Non-REM stage 1: deeper sleep = 50% of all sleep
Non-REM stage 1: deep sleep - night tremors, bed wetting and sleep walking occur here
REM: dreaming occurs, loss of muscle tone/erections
REM can dysfunction - if the patient is DREAMING - must be REM regardless of whether there is hypotonia or not
On ECG:
Theta (N-REM1) → Sleep spindles/K-complexes (N-REM2) → Delta (N-REM3) → Beta (REM)
The Sleep Doctor’s Brain
What is specificity and how is it calculated?
A test’s specificity is the proportion of people without the disease who will have a negative result.
Specificity = True Negatives / (True Negatives + False Positives)
What is the p value?
A measure of the probability that an observed difference could have occurred just by random chance, assuming that the null hypothesis is true
Therefore = to a T1 error
Or, equal to the chance that the value of our study or one at least as extreme as it, could have occurred by chance if the null hypothesis is true
What is the difference between a T1 and T2 error?
T1 = the null hypothesis is rejected when it is true T2 = the null hypothesis is accepted when it is false
What is the ‘power’ and how is it calculated?
the probability of (correctly) rejecting the null hypothesis when it is false
power = 1 - the probability of a type II error
power can be increased by increasing the sample size
What type of vitamin deficiency is pyridoxine and what symptoms?
vitamin B6
This may cause some similar symptoms to pellagra, but classically also peripheral neuropathy
What type of vitamin deficiency produces pellagra?
Vitamin B3 (niacin)
How to calculate the left ventricular ejection volume?
Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%
Stroke volume = end diastolic LV volume - end systolic LV volume
How to calculate cardiac output?
Cardiac output = stroke volume x heart rate
What is the p53 gene, what Chr is it located on and when is it commonly seen?
p53 is a TUMOUR SUPPRESSOR GENE located on chromosome 17p. It is the most commonly mutated gene in breast, colon and lung cancer
What is p53s role in the cell cycle?
If it detects damaged DNA, it pauses the process to allow for the DNA to be repaired or destroyed. Therefore if there is a mutation here, the cell cycle won’t be halted and it will result in a short G1 and proliferation of the damaged cell
What is Li-Fraumeni syndrome?
A rare AD disorder characterised by the early onset of a variety of cancers such as sarcoma, breast cancer and leukaemias. It is caused by mutation in the p53 gene.
What is the pre-test probability?
Just the prevalence of the disease in the population
What is the post-test probability?
The proportion of patients with that particular test result who have the target disorder
Post-test probability = post test odds / (1 + post-test odds)
What are the pre-test odds?
The odds that the patient has the target disorder before the test is carried out
Pre-test odds = pre-test probability / (1 - pre-test probability)
What are the post-test odds?
The odds that the patient has the target disorder after the test is carried out
Post-test odds = pre-test odds x likelihood ratio
where the likelihood ratio for a positive test result = sensitivity / (1 - specificity)
What is the inheritance and deficiency in Fabry’s disease?
X-linked recessive
deficiency of alpha-galactosidase A
Symptoms of Fabry’s disease?
burning pain/paraesthesia in childhood angiokeratomas lens opacities proteinuria early cardiovascular disease
F - foggy lens A - angiokeratomas B - burning pain R - renal: proteinurea Y do I have cardiac problems too
What are the three possible intended outcomes of trials? What sample sizes are needed?
superiority: large sample size needed to show a significant benefit over an existing treatment
equivalence: confidence interval of the difference between the two drugs lies within the equivalence margin then the drugs may be assumed to have a similar effect
non-inferiority: similar to equivalence trials, but only the lower confidence interval needs to lie within the equivalence margin (i.e. -delta). Small sample sizes are needed for these trials. Once a drug has been shown to be non-inferior large studies may be performed to show superiority
What electrolyte movement occurs during: Rapid depolarisation Early repolarisation Plateau Final repolarisation Restoration of ionic concentrations
Rapid depolarisation - rapid Na influx Early repolarisation - K efflux Plateau - slow Ca influx Final repolarisation - K efflux Restoration of ionic concentrations - resting potential is restored by Na+/K+ ATPase
Speed of conduction along atrial fibres? AV node conduction? ventricular conduction?
atrial fibres - 1m/sec
AV node conduction - 0.05m/sec
Purkinje fibres - 2-4m/sec -> fastest in the heart
In which foods would you find riboflavin (vit B2)?
Widely found in plant and animal food
eggs, green vegetables and milk
What is the importance of vitamin A and what can a deficiency in it lead to?
Vit A - needed to produce rhodopsin, a light-absorbing molecule used for low light and colour vision
Deficiency = can cause blindness
Other than Wernicke’s, what can thiamine (B1) deficiency cause?
dry beriberi: peripheral neuropathy
wet beriberi: dilated cardiomyopathy
What can vitamin B3 produce?
Pellagra
Which nerve roots supply the musculocutaneous nerve and what are the common injuries?
C5-C7
Elbow flexion
Sensory to lateral part of the forearm
Rarely independent injury
Which nerve roots supply the axillary nerve and what are the common injuries?
C5-C6
Shoulder abduction
Sensory to inferior region of the deltoid muscle
May be caused by a humeral neck fracture/dislocation
Which nerve roots supply the radial nerve and what are the common injuries?
C5-C8
Extension (forearm, wrist, fingers, thumb)
Defect causes WRIST DROP
Sensory to small area between the dorsal aspect of the 1st and 2nd metacarpals
May be caused by a humeral midshaft fracture
Which nerve roots supply the medial nerve and what are the common injuries?
Motor to LOAF muscles
Sensory to latter 3.5 fingers
Caused by carpel tunnel
LOAF = Lateral two lumbricals Opponens pollis Abductor pollis brevis Flexor pollis brevis
Which nerve roots supply the ulnar nerve and what are the common injuries?
C8 -T1
Motor: Intrinsic hand muscles except LOAF
Sensory: Medial 1½ fingers
May be caused by medial epicondyle fracture
Which nerve roots supply the long thoracic nerve and what are the common injuries?
C5-C7
Damage results in a winged scapula
Often during sport, can be following mastectomy
What is Erb-Duchenne palsy and what causes it?
(‘waiter’s tip’)
due to damage of the upper trunk of the brachial plexus (C5,C6)
may be secondary to shoulder dystocia during birth
the arm hangs by the side and is internally rotated, elbow extended
What is Klumpke injury?
due to damage of the lower trunk of the brachial plexus (C8, T1)
May be secondary to shoulder dystocia during birth. Also may be caused by a sudden upward jerk of the hand
associated with Horner’s syndrome
What is the mechanism of PCR?
Add to the cauldron:
- DNA section, 2x DNA primers, free nucleotides (A,T,C,G) and the Taq polymerase enzyme
Heat up sample - bonds between DNA will break
Cool it down - primers will bond to section of the DNA
Heat up again a bit - Taq enzyme with fill in the gaps with nucleotides
Overall the amount of DNA doubles with each cycle -> DNA amplification
What is the chi-squared test?
used to compare proportions or percentages e.g. compares the percentage of patients who improved following two different interventions
What is the odds and odds ratio?
Odds are a ratio of the number of people who incur a particular outcome to the number of people who do not incur the outcome. The odds ratio may be defined as the ratio of the odds of a particular outcome with experimental treatment and that of control.
See pass med for example
Which kidney lies higher than the other?
Left - approximately 1.5cm higher
think about your liver being in the way
Which 3 structures are in direct contact with the R and L kidney?
R: Right suprarenal gland
Duodenum
Colon
L: Left suprarenal gland
Pancreas
Colon
What is the mechanism of NO?
NO is produced in endothelial cells and travels to SM cells
Here it is involved in the formation of cGMP which is involved in the relaxation of vessel walls causing vasodilation
What is prevalence/incidence bias (Neyman bias)?
When a study is investigating a condition that is characterised by early fatalities or silent cases. It results from missed cases being omitted from calculations
What is admission bias (Berkson’s bias)?
Cases and controls in a hospital case control study are systematically different from one another because the combination of exposure to risk and occurrence of disease increases the likelihood of being admitted to the hospital
What is recall bias?
Difference in the accuracy of the recollections retrieved by study participants, possibly due to whether they have disorder or not
What is publication bias?
Failure to publish results from valid studies, often as they showed a negative or uninteresting result. Important in meta-analyses where studies showing negative results may be excluded
What is work-up bias?
In studies which compare new diagnostic tests with gold standard tests, work-up bias can be an issue. Sometimes clinicians may be reluctant to order the gold standard test unless the new test is positive, as the gold standard test may be invasive (e.g. tissue biopsy). This approach can seriously distort the results of a study, and alter values such as specificity and sensitivity. Sometimes work-up bias cannot be avoided, in these cases it must be adjusted for by the researchers.
What is expectation bias?
Only a problem in non-blinded trials. Observers may subconsciously measure or report data in a way that favours the expected study outcome.
What is the Hawthorne effect?
Describes a group changing it’s behaviour due to the knowledge that it is being studied
Studied efficiency in The Hawthorne Works, people worked a lot harder during observation
What is late-look bias?
Gathering information at an inappropriate time e.g. studying a fatal disease many years later when some of the patients may have died already
What is procedure bias?
Occurs when subjects in different groups receive different treatment
What is lead-time bias?
Occurs when two tests for a disease are compared, the new test diagnoses the disease earlier, but there is no effect on the outcome of the disease
Where is the majority of iron found in the body?
Hb
What is the standard error of the mean?
how ‘accurate’ the calculated sample mean is from the true population mean
Calculated by: standard deviation / square root (sample size)
i.e. if you ask 50 people for a specific outcome, the mean response = sample mean. Then ask 50x 50 more people and take their sample means. When you plot all these on a graph you will get a bell curve with all of the sample means i.e. standard sampling mean. When you compare these to the true mean = the standard error of the mean. This will obvious decrease (i.e. the mean will become more accurate) as the sample size gets bigger.
What are the four main types of membrane receptors?
ligand-gated ion channels
tyrosine kinase receptors
guanylate cyclase receptors
G protein-coupled receptors
What are ligand-gated ion channel receptors?
generally mediate fast responses
The ligand binds to the channel to open it up and allow electrolytes to pass through
e.g. nicotinic acetylcholine, GABA-A & GABA-C, glutamate receptors
What are guanylate cyclase receptors?
contain intrinsic enzyme activity
e.g. atrial natriuretic factor, BNP
What are tyrosine kinase receptors?
Like iron channels, but things can’t pass through. The ligand binds to the receptor and activates enzymes on the inside of the cell.
Think kinase = enzyme.
receptor tyrosine kinase: insulin, insulin-like growth factor (IGF), epidermal growth factor (EGF)
non-receptor tyrosine kinase: PIGG(L)ET: Prolactin, Immunomodulators (cytokines IL-2, Il-6, IFN), GH, G-CSF, Erythropoietin and Thromobopoietin
What are G protein-coupled receptors?
generally mediate slow transmission and affect metabolic processes
The outside of the cell is activated by a wide variety of extracellular signals
It folds in and out of the cell membrane 7 times, and is therefore know as having 7-helix membrane-spanning domains
On the inside of the cell there are 3 main subunits: alpha, beta and gamma. These are all normally bound to GDP when the channel isn’t activated. However when the receptor is activated, it drops GDP and binds to GTP, then the alpha subunit breaks off (with GTP) leaving the beta and gamma subunits behind. This alpha unit-GTP complex can go on to activate other intracellular processes
G proteins are named according to the alpha subunit (Gs, Gi, Gq)
What is the difference between Gs, Gi and Gq?
Gs: Stimulates adenylate cyclase → increases cAMP → activates protein kinase A (ex. B1 + B2 receptors)
Gi: Inhibits adenylate cyclase → decreases cAMP → inhibits protein kinase A (ex. M2 + A2 receptors)
Gq: Activates phospholipase C → activates protein kinase C (ex. M1 + A1 receptors)
What are Merkel cells?
Found in the skin
May be involved in touch
What are langerhans cells?
These cells determine the appropriate adaptive immune response (inflammation or tolerance) by interpreting the microenvironmental context in which they encounter foreign substances
Layers of the skin?
Come (corneum) Let's (lucidum) Get (granulosum) Sun (spinosum) Burnt (basale)
Where are the melanocytes found?
Stratum basale
Where are keratinocytes formed?
Formed in the stratum basale
Rubella, characteristic congenital symptoms?
SN deafness
Cataracts
Cardiac abnormalities e.g. PDA
Toxoplasmosis, characteristic congenital symptoms?
Cerebral calcification
Chorioretinitis
Hydrocephalus
CMV, characteristic congenital symptoms?
Growth retardation
Purpuric skin lesions
What is an endocardial cushion defect?
AVSD
Are IFa, IFb and IFg type 1 or type 2 IFs?
IFa and IFb - type 1 receptors
IFg - (the only) type 2 receptors
What produces IFa? What produces IFb? IFg?
IFa - leukocytes
IFb - fibroblasts
IFg - predominantly by NK cells, also T cells
gnaw bf
What are interferons?
Interferons (IFN) are cytokines released by the body in response to viral infections and neoplasia.
How to calculate the likelihood ratio for a positive result?
sensitivity / (1 - specificity)
How to calculate the likelihood ratio for a negative result?
(1 - sensitivity) / specificity
What are the features of DiGeorge syndrome?
caused by T-cell deficiency and dysfunction (because the thymus is under produced so nowhere to store)
'CATCH22' is a mnemonic used to describe some of the key features of this condition: C - Cardiac abnormalities - TOF A - Abnormal facies T - Thymic aplasia C - Cleft palate H - Hypocalcaemia/ hypoparathyroidism 22 - Caused by chromosome 22 deletion
Helper T cells, which of the MHC class do they recognise?
Recognises antigens presented by MHC class II molecules
Cytotoxic T cells, which of the MHC class do they recognise?
Recognises antigens presented by MHC class I molecules
What are the 4 classic antigen presenting cells?
dendritic cells, macrophages, Langerhans cells and B cells
Most common genetic abnormality in Prader-Willi syndrome?
Microdeletion of paternal 15q11-13
Think ‘illi’ (4 x 1s)
Which conditions are X-linked recessive inheritance?
Be Wise, Fools GOLD Heeds (false) Hope Brutons Wiskott Aldrich Fabry G6PD Ocular albinism Lesch-Nyhan Duchenne (and Becker) Haemophilia Hunter
What are the common cardiac abnormalities in Turner’s syndrome?
Bicuspid aortic valve and aortic coarctation
T helper cell 1 secretes what?
secrete IFN-gamma, IL-2, IL-3
Think Th1, 2, 3 .. go!
T helper cell 2 secretes what?
IL-4, IL-5, IL-6, IL-10, IL-13
What is Gaucher’s disease?
Most common lipid storage disorder resulting in accumulation of glucocerebrosidase in the brain, liver and spleen. Key features include hepatosplenomegaly, aseptic necrosis of the femur
How soon after successful treatment of pneumothorax can you fly?
2wks
What are the different levels of evidence?
Ia - evidence from meta-analysis of randomised controlled trials
Ib - evidence from at least one randomised controlled trial
IIa - evidence from at least one well designed controlled trial which is not randomised
IIb - evidence from at least one well designed experimental trial
III - evidence from case, correlation and comparative studies
IV - evidence from a panel of experts
Which drugs reduce renin secretion?
beta-blockers, NSAIDs
What is detected in Southern, Northern and Western blotting tests?
SNOW (South - NOrth - West)
DROP (DNA - RNA - Protein)
Which type of HLA is dermatitis herpetiformis, Sjogren’s syndrome, primary biliary cirrhosis associated with?
HLA-DR3
Which chromosome encodes for HLA antigens?
Chr 6
takes 6 lines to write HLA
Which HLA encode for coeliac disease?
HLA-DQ2/DQ8
How to calculate the absolute risk reduction?
Experimental event rate - the control event rate
How to calculate the number needed to treat?
1/absolute risk reduction
Difference between T1 and T2 muscle fibres?
T2 - All A's Absence of myoglobin so white in colour Active - occurs on sudden movement Fuelled by ATP Low mitochondrial density
T1 Myoglobin gives it the colour red Used for sustained force Fuelled by triglycerides High mitochondrial density
Difference between T1 and T2 muscle fibres?
T2 - All A's Absence of myoglobin so white in colour Active - occurs on sudden movement Fuelled by ATP Low mitochondrial density
T1 Myoglobin gives it the colour red Used for sustained force Fuelled by triglycerides High mitochondrial density One slow, fat, red Ox
What are 4 examples of mitochondrial diseases?
Leber optic atrophy
Kearns-Sayre syndrome
MALAS syndrome
MERRF syndrome
What percentage of data lies outside of a confidence interval within 2 standard deviations of the mean?
CI = 95.4% Outside = 4.6%, 2.3% each side
Which type of cytokine is responsible for activating macrophages?
IF-gamma
What is the difference between a box plot, a forest plot and a funnel plot?
Genetic abnormality in fragile X?
Tri-nucleotide repeat disorder
Symptoms of fragile X?
Xtra large testes Xtra large ears Xtra large forehead Hypotonia MV prolapse Autism
What isthe cushing’s reflex and what is the mechanism?
Cushings reflex describes a trio of bradycardia, HTN and irregular breathing in the case of raised ICP.
Also wide pulse pressure.
Raised ICP means that the blood has to be pumped harder to perfuse the brain = HTN.
This HTN + backlog from the brain causes baroreceptors to be stimulated and bradycardia to develop.
As the brain swells it presses on the brainstem which causes irregular breathing.
Noonan’s chromosome defect and inheritance pattern?
Chromosome 12
Noon-ans
AD
What is noonan’s syndrome and what are the key features?
Male Turner's Same as turners with - pulmonary valve stenosis Low set ears Coagulant factor 11 deficiency
Which HLA is associated with narcolepsy and goodpastures?
HLA DR2
In which order would the mode, mean and median fall in negatively skewed distribution?
Mode > Median > Mean
What is the main component of pulmonary surfactant?
DPPC
What is Reverse transcriptase PCR?
The same as normal PCR but the first step is different
RNA copied with the help of the reverse transcriptase enzyme and a primer segment. This produces cDNA. This is then copied in the same process as normal PCR
What is the function of IL-1 and where is it produced?
Function: induces fever, acute inflammation
Produced by macrophages
What is the most common inheritance pattern for Down Syndrome?
Maternal non-disjunction
During meiosis, the chromosomes don’t split equally resulting in three chr21
Which type of cell secretes surfactant and when do they develop?
T2 pneumocytes
Start to develop around 24wks but don’t full develop until 35wks
What are club cells?
Prev clara cells
Involved in airway detoxification and airway repair after injury
What is the shape of IgGAMDE?
IgGAED - monomers
IgM (the one that should be a monomer because it starts with M but alas that is never the case) = pentamer
What is the predominant role of IgG, A and M?
IgG - Enhance phagocytosis of bacteria and viruses
IgA - predominant Ig found in breast milk. Also found in the secretions of digestive, resp and urogenital tracts and systems. Provides localized protection on mucous membranes
IgM - First to respond to infection. Fixes complement but does not pass to the fetal circulation
In what order are the Ig most abundant in the blood?
G A M D E
What is expressivity in genetics?
the extent to which a particular genotype is expressed in the phenotype of an individual
e.g. Marfans - shows varied phenotypic presentation for the genotype
What is penetrance in genetics?
refers to the proportion of the population who have a particular mutation also having the associated disease
e.g. BRCA-1 in breast cancer
What is Lynch syndrome?
also known as hereditary non-polyposis colorectal cancer (HNPCC), is the most common cause of hereditary colorectal (colon) cancer
Which cancers does HPV 16/18 predispose you to?
Cervical cancer Anal cancer Penile cancer Vulval cancer Oropharyngeal cancer
How do tumour suppressor genes and oncogenes lead to cancer?
Tumor suppressor genes - loss of function results in an increased risk of cancer (think p53)
Oncogenes - gain of function results in an increased risk of cancer
What do the following oncogenes predispose you to? c-MYC n-MYC ABL BCL-2 RET RAS
c-MYC - Burkitt's lymphoma n-MYC - Neuroblastoma ABL - CML BCL-2 - follicular lymphoma RET - MENII + III RAS - many Ca's, esp pancreatic
What is leptin?
thought to play a key role in the regulation of body weight. It is produced by adipose tissue and acts on satiety centres in the hypothalamus and decreases appetite. More adipose tissue (e.g. in obesity) results in high leptin levels.
Role of ghrelin?
Induces feeling of hunger
Causes of massive splenomegaly?
Myelofibrosis chronic Myeloid leukaemia visceral leishManiasis (kala-azar) Malaria Gaucher's syndrome
What are person-years?
The cumulative number of years for which you have studied each person, number of people x years examined them
What is the relative risk (risk ratio)?
incidence of exposed individuals / incidence of unexposed individuals
What does intention-to-treat mean?
Including all participants who were initially randomised into each group in the outcome data, rather than ruling out certain patients based on factors e.g. compliance with medication
When is the hazard ratio used?
Similar to risk ratio but used when variables do not stay constant in time
E.g. if looking at survival risk, hazard ratio is more appropriate as will take into account changes with time
Main site of ANP excretion?
R atrium (opposite to BNP)
What is the main function of ANP?
natriuretic, i.e. promotes excretion of sodium
lowers BP
Which conditions have trinucleotide repeats?
Fragile X (CGG) Huntington's (CAG) myotonic dystrophy (CTG) Friedreich's ataxia* (GAA) spinocerebellar ataxia spinobulbar muscular atrophy dentatorubral pallidoluysian atrophy
What is the purpose of a funnel plot?
To show publication bias in meta-analyses Effect size (e.g. odds ratio) on the horizontal axis and a measure of the studies’ standard error on the vertical axis (which is linked to study size)
What occurs to the lung vasculature during hypoxia?
A fall in the partial pressure of oxygen in the blood leads to vasoconstriction of the pulmonary arteries. This allows blood to be diverted to better aerated areas of the lung and improves the efficiency of gaseous exchange
What occurs in vitamin D resistant rickets?
Hypophosphataemia
Normal serum calcium
X-lined dominant
Require high dose vitamin D
What is the variance and how is it calculated?
Variance is a measure of the spread of scores away from the mean.
Variance = square of standard deviation
What are the stages of mitosis?
Interphase - before
Prophase - organisation begins
Prometaphase - nuclear membrane breaks down, microtubules attach to chromosomes
Metaphase - chromosomes align in the middle of the cell
Anaphase - chromosomes pulled to opposite ends
Telephase - chromosomes arrive at opposite ends
Cytokinesis - breaks into two cells
Where is the majority of Na absorbed in the nephron
PCT (50%)
Loop (40%)
DCT (5%)
CD (2%)
What else is absorbed in the PCT?
AA, bicarbonate, phosphate, glucose
Where is the nephron can water not be absorbed?
Thick ascending limb
What is fanconi’s syndrome?
Disorder of reabsorption in the PCT
What can cause proximal RTA?
Inherited, sjogren’s, heavy metal poisoning, myeloma
What is the overall effect of vitamin D on Ca and Phos?
Increases plasma concentrations of both
In which stage of sleep can you act out your dreams?
REM
What is the HaLdane effect?
Describes the scenario where the presence of O2 into the blood causes the Hb molecule to bind less well to its CO2 molecule. This is useful in the lungs where gas exchanges needs to occur
What is the Bohr effect?
Describes the scenario where the presence of CO2 causes the Hb molecule to bind less well to its O2 molecule. This happens in the tissues where the presence of CO2 helps to release O2 from the Hb so it can be taken in by the cells
What is regression analysis?
Used to understand whether there is a relationship between a dependant variable and one or more independent variables. The most common form of regression analysis is linear regression.
How to remember the order of the categories in Gell and Coombs?
ABCDG Anaphylactic-1 antiBody-2 Complex-3 Delayed-4 Graves & Gravis -5
What is the power in statistics?
the probability of (correctly) rejecting the null hypothesis when it is false
Where is GH produced and from what cells?
Anterior pituitary: Somatotrophs comprise 50% of the cells of the anterior pituitary gland
