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Basic science Flashcards

1
Q

eGFR equation

A

GFR = ( urine concentration (mmol/l) x urine volume (ml/min) ) / plasma concentration (mmol/l)

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2
Q

MA of RCTs level of evidence

A

Ia

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3
Q

RCT level of evidence

A

1b

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4
Q

Control trial, not randomised level of evidence

A

2a

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5
Q

2b level of evidence

A

evidence from at least one well designed experimental trial

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6
Q

3 level of evidence

A

evidence from case, correlation and comparative studies

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7
Q

4 level of evidence

A

evidence from a panel of experts

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8
Q

what regulates cell cycle

A

proteins called cyclins which in turn control cyclin-dependent kinase (CDK) enzymes.

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9
Q

phases of cell cycle

A

G0,G1,S,G2,M

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10
Q

G0

A

‘resting’ phase

quiescent cells such as hepatocytes and more permanently resting cells such as neurons

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11
Q

G1

A

Gap 1, cells increase in size
determines length of cell cycle
under influence of p53

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12
Q

regulatory proteins G1

A

Cyclin D / CDK4, Cyclin D / CDK6 and Cyclin E / CDK2: regulates transition from G1 to S phase

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13
Q

S

A

Synthesis of DNA, RNA and histone

centrosome duplication

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14
Q

regulatory proteins S

A

Cyclin A / CDK2: active in S phase

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15
Q

G2

A

Gap 2, cells continue to increase in size

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16
Q

regulatory preoteins G2

A

Cyclin B / CDK1: regulates transition from G2 to M phase

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17
Q

M

A

Mitosis - cell division

the shortest phase of the cell cycle

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18
Q

negative predictive value equation

A

TN / (TN + FN)

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19
Q

sensitivity equation

A

TP / (TP + FN )

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20
Q

specificity equation

A

TN / (TN + FP)

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21
Q

PPV equation

A

TP / (TP + FP)

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22
Q

likelihood ratio for a positive result

A

sensitivity / (1 - specificity)

How much the odds of the disease increase when a test is positive

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23
Q

likelihood ratio negative test

A

(1 - sensitivity) / specificity

How much the odds of the disease decrease when a test is negative

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24
Q

most common congenital infection in the UK

A

CMV

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25
Q 
Sensorineural deafness
Congenital cataracts
Congenital heart disease (e.g. patent ductus arteriosus)
Glaucoma
congenital infection
A

rubella

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26
Q

Cerebral calcification
Chorioretinitis
Hydrocephalus

congenital infection

A

toxoplasmosis

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27
Q

Growth retardation
Purpuric skin lesions

congenital infection

A

CMV

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28
Q

audit definition

A

a quality improvement process that seeks to improve patient care and outcomes through systematic review of care against explicit criteria and the implementation of change

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29
Q

what phase of mitosis does vincristine act on?

A

metaphase

These drugs bind to tubulin stopping the polymerisation and assembly of microtubules. This, in turn, disrupts spindle formation arresting mitosis at metaphase.

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30
Q

what happens in prophase

A

Chromatin in the nucleus condenses

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31
Q

prometaphase

A

Nuclear membrane breaks down allowing the microtubules to attach to the chromosomes

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32
Q

metaphase

A

Chromosomes aligned at middle of cell

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33
Q

anaphase

A

The paired chromosomes separate at the kinetochores and move to opposite sides of the cell

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34
Q

telophase

A

Chromatids arrive at opposite poles of cell

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35
Q

cytokinesis

A

Actin-myosin complex in the centre of the cell contacts resulting in it being ‘pinched’ into two daughter cells

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36
Q

parametric tests

A

Student’s t-test - paired or unpaired*

Pearson’s product-moment coefficient - correlation

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37
Q

non-parametric tests

A

Mann-Whitney U test
compares ordinal, interval, or ratio scales of unpaired data
Wilcoxon signed-rank test
compares two sets of observations on a single sample, e.g. a ‘before’ and ‘after’ test on the same population following an intervention
chi-squared test
used to compare proportions or percentages e.g. compares the percentage of patients who improved following two different interventions
Spearman, Kendall rank - correlation

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38
Q

what are compliment

A

series of proteins that circulate in plasma and are involved in the inflammatory and immune reaction of the body. Complement proteins are involved in chemotaxis, cell lysis and opsonisation

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39
Q

C1 deficiency

A 
C1 inhibitor (C1-INH) protein deficiency
causes hereditary angioedema
C1-INH is a multifunctional serine protease inhibitor
probable mechanism is uncontrolled release of bradykinin resulting in oedema of tissues
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40
Q

classical pathway compliment and deficiency

A

C1q, C1rs, C2, C4 deficiency (classical pathway components)
predisposes to immune complex disease
e.g. SLE, Henoch-Schonlein Purpura

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41
Q

c3 deficiency

A

predisposes to bacterial infections

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42
Q

C5 deficiency

A

predisposes to Leiner disease

recurrent diarrhoea, wasting and seborrhoeic dermatitis

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43
Q

C5-9 deficiency

A

encodes the membrane attack complex (MAC)

particularly prone to Neisseria meningitidis infection

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44
Q

IL-1 source and functions

A

Macrophages Acute inflammation

Induces fever

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45
Q

IL-2 source and functions

A

Th1 cells Stimulates growth and differentiation of T cell response

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46
Q

IL-3 source and functions

A

Activated T helper cells Stimulates differentiation and proliferation of myeloid progenitor cells

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47
Q

IL-4 source and functions

A

Th2 cells Stimulates proliferation and differentiation of B cells

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48
Q

IL-5 source and functions

A

Th2 cells Stimulate production of eosinophils

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49
Q

IL-6 source and functions

A

Macrophages, Th2 cells Stimulates differentiation of B cells

Induces fever

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50
Q

IL-8 source and functions

A

Macrophages Neutrophil chemotaxis

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51
Q

IL-10 source and functions

A

Th2 cells
Inhibits Th1 cytokine production
Also known as human cytokine synthesis inhibitory factor and is an ‘anti-inflammatory’ cytokine

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52
Q

IL-12 source and functions

A

Dendritic cells, macrophages, B cells

Activates NK cells and stimulates differentiation of naive T cells into Th1 cells

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53
Q

TNF alpha source and functions

A

Macrophages Induces fever

Neutrophil chemotaxis

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54
Q

interferon Y source and functions

A

Th1 cells Activates macrophages

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55
Q

type 1 error

A

the null hypothesis is rejected when it is true - i.e. Showing a difference between two groups when it doesn’t exist, a false positive. This is determined against a preset significance level (termed alpha). As the significance level is determined in advance the chance of making a type I error is not affected by sample size. It is however increased if the number of end-points are increased. For example if a study has 20 end-points it is likely one of these will be reached, just by chance.

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56
Q

type 2 error

A

the null hypothesis is accepted when it is false - i.e. Failing to spot a difference when one really exists, a false negative. The probability of making a type II error is termed beta. It is determined by both sample size and alpha

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57
Q

define the power of a study

A

the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference
power = 1 - the probability of a type II error
power can be increased by increasing the sample size

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58
Q

what is atrial nartiuretic peptide?

A

secreted mainly from myocytes of right atrium and ventricle in response to increased blood volume
secreted by both the right and left atria (right&raquo_space; left)
28 amino acid peptide hormone, which acts via cGMP
degraded by endopeptidases

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59
Q

effects of ANP

A

natriuretic, i.e. promotes excretion of sodium
lowers BP
antagonises actions of angiotensin II, aldosterone

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60
Q

artherosclerosis stages

A

initial endothelial dysfunction is triggered by a number of factors such as smoking, hypertension and hyperglycaemia
this results in a number of changes to the endothelium including pro-inflammatory, pro-oxidant, proliferative and reduced nitric oxide bioavailability
fatty infiltration of the subendothelial space by low-density lipoprotein (LDL) particles
monocytes migrate from the blood and differentiate into macrophages. These macrophages then phagocytose oxidized LDL, slowly turning into large ‘foam cells’. As these macrophages die the result can further propagate the inflammatory process.
smooth muscle proliferation and migration from the tunica media into the intima results in formation of a fibrous capsule covering the fatty plaque.

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61
Q

artherosclerosis complications

A

the plaque forms a physical blockage in the lumen of the coronary artery. This may cause reduced blood flow and hence oxygen to the myocardium, particularly at times of increased demand, resulting clinically in angina
the plaque may rupture, potentially causing a complete occlusion of the coronary artery. This may result in a myocardial infarction

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62
Q

what is p53

A

p53 is a tumour suppressor gene located on chromosome 17p. It is the most commonly mutated gene in breast, colon and lung cancer.
p53 is thought to play a crucial role in the cell cycle, preventing entry into the S phase until DNA has been checked and repaired. It may also be a key regulator of apoptosis

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63
Q

what is Li-fraumeni syndrome?

A

rare autosomal dominant 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.

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64
Q

vitamin D function

A

increases plasma calcium and plasma phosphate
increases renal tubular reabsorption and gut absorption of calcium
increases osteoclastic activity
increases renal phosphate reabsorption

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65
Q

vitamin d deficiency causes

A

rickets: seen in children
osteomalacia: seen in adults

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66
Q

cerebral metastasis features

A

Metastatic brain cancer is the most common form of brain tumours. They are often multiple and not treatable with surgical intervention.

Tumours that most commonly spread to the brain include:
lung (most common)
breast
bowel
skin (namely melanoma)
kidney
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67
Q

glioblastoma features

A

Glioblastoma is the most common primary tumour in adults and is associated with a poor prognosis (~ 1yr).

  • On imaging they are solid tumours with central necrosis and a rim that enhances with contrast. Disruption of the blood-brain barrier and therefore are associated with vasogenic oedema.
  • Histology: Pleomorphic tumour cells border necrotic areas
  • Treatment is surgical with postoperative chemotherapy and/or radiotherapy. Dexamethasone is used to treat the oedema.
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68
Q

meningioma features

A

The second most common primary brain tumour in adults

  • Meningiomas are typically benign, extrinsic tumours of the central nervous system. They arise from the dura mater of the meninges and cause symptoms by compression rather than invasion.
  • They typically are located at the falx cerebri, superior sagittal sinus, convexity or skull base.
  • Histology: Spindle cells in concentric whorls and calcified psammoma bodies
  • Investigation is with CT (will show contrast enhancement) and MRI, and treatment will involve either observation, radiotherapy or surgical resection.
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69
Q

schwannoma features

A

A vestibular schwannoma (previously termed acoustic neuroma) is a benign tumour arising from the eighth cranial nerve (vestibulocochlear nerve). Often seen in the cerebellopontine angle. It presents with hearing loss, facial nerve palsy (due to compression of the nearby facial nerve) and tinnitus.

  • Neurofibromatosis type 2 is associated with bilateral vestibular schwannomas.
  • Histology: Antoni A or B patterns are seen. Verocay bodies (acellular areas surrounded by nuclear palisades)
  • Treatment may involve observation, radiotherapy or surgery.
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70
Q

pilocytic astrocytoma features

A

The most common primary brain tumour in children

• Histology: Rosenthal fibres (corkscrew eosinophilic bundle)

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71
Q

medulloblastoma features

A

A medulloblastoma is an aggressive paediatric brain tumour that arises within the infratentorial compartment. It spreads through the CSF system. Treatment is surgical resection and chemotherapy.

• Histology: Small, blue cells. Rosette pattern of cells with many mitotic figures

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72
Q

ependymoma features

A
  • Commonly seen in the 4th ventricle
  • May cause hydrocephalus
  • Histology: perivascular pseudorosettes
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73
Q

oligodendroma features

A

Benign, slow-growing tumour common in the frontal lobes

• Histology: Calcifications with ‘fried-egg’ appearance

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74
Q

haemangioblastoma features

A
  • Vascular tumour of the cerebellum
  • Associated with von Hippel-Lindau syndrome
  • Histology: foam cells and high vascularity
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75
Q

pituitary adenoma features

A

Pituitary adenomas are benign tumours of the pituitary gland. They are either secretory (producing a hormone in excess) or non-secretory. They may be divided into microadenomas (smaller than 1cm) or macroadenoma (larger than 1cm).

  • Patients will present with the consequences of hormone excess (e.g. Cushing’s due to ACTH, or acromegaly due to GH) or depletion. Compression of the optic chiasm will cause a bitemporal hemianopia due to the crossing nasal fibers.
  • Investigation requires a pituitary blood profile and MRI. Treatment can either be hormonal or surgical (e.g. transphenoidal resection).
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76
Q

craniopharyngioma features

A

Most common paediatric supratentorial tumour

  • A craniopharyngioma is a solid/cystic tumour of the sellar region that is derived from the remnants of Rathke’s pouch. It is common in children, but can present in adults also. It may present with hormonal disturbance, symptoms of hydrocephalus or bitemporal hemianopia.
  • Histology: Derived from remnants of Rathke pouch
  • Investigation requires pituitary blood profile and MRI. Treatment is typically surgical with or without postoperative radiotherapy.
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77
Q

vitamin c functions

A

antioxidant
collagen synthesis: acts as a cofactor for enzymes that are required for the hydroxylation proline and lysine in the synthesis of collagen
facilitates iron absorption
cofactor for norepinephrine synthesis

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78
Q

vitamin c deficiency features

A

gingivitis, loose teeth
poor wound healing
bleeding from gums, haematuria, epistaxis
general malaise

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79
Q

what is fragile X?

A

trinucleotide repeat disorder

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80
Q

fragile X features

A 
Features in males
learning difficulties
large low set ears, long thin face, high arched palate
macroorchidism
hypotonia
autism is more common
mitral valve prolapse

Features in females (who have one fragile chromosome and one normal X chromosome) range from normal to mild

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81
Q

equation for standard error mean

A

SEM = SD / square root (n)
where SD = standard deviation and n = sample size
therefore the SEM gets smaller as the sample size (n) increases

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82
Q

95% confidence interval equation

A

lower limit = mean - (1.96 * SEM)

upper limit = mean + (1.96 * SEM)

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83
Q

collagen structure

A

Composed of 3 polypeptide strands that are woven into a helix, usually a combination of glycine with either proline or hydroxyproline plus another amino acid
Numerous hydrogen bonds exist within molecule to provide additional strength
Many subtypes but commonest subtype is I (90% of bodily collagen), tissues with increased levels of flexibility have increased levels of type III collagen
Vitamin C is important in establishing cross-links
Synthesised by fibroblasts

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84
Q

where is type 1 collagen found and what are the associated conditions?

A

Bone, skin, tendon Osteogenesis imperfecta

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85
Q

where is type 2 collagen found ?

A

Hyaline cartilage, vitreous humour

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86
Q

where is type 3 collagen found and what are the associated conditions?

A

Reticular fibre, granulation tissue Vascular variant of Ehlers-Danlos syndrome

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87
Q

where is type 4 collagen found and what are the associated conditions?

A

Basal lamina, lens, basement membrane Alport syndrome, Goodpasture’s syndrome

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88
Q

where is type 5 collagen found and what are the associated conditions?

A

Most interstitial tissue, placental tissue Classical variant of Ehlers-Danlos syndrome

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89
Q

dry beriberi

A

B1 (thiamine deficiency)

peripheral neuropathy

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90
Q

wet beriberi

A

B1 (thiamine deficiency)

dilated cardiomyopathy

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91
Q

causes of thiamine deficiency

A

alcohol excess. Thiamine supplements are the only routinely recommend supplement in patients with alcoholism
malnutrition

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92
Q

LVEF equation

A

Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%

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93
Q

stroke volume equation

A

Stroke volume = end diastolic LV volume - end systolic LV volume

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94
Q

factors which increase pulse pressure

A

a less compliant aorta (this tends to occur with advancing age)
increased stroke volume

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95
Q

systemic vascular resistance calculation

A

Systemic vascular resistance = mean arterial pressure / cardiac output

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96
Q

vitamin k dependent clotting factors

A

II, VII, IX, X

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97
Q

how are oncogenes different from tumor supressor genes?

A

Tumor suppressor genes - loss of function results in an increased risk of cancer

Oncogenes - gain of function results in an increased risk of cancer

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98
Q

CML associated gene

A

ABL

Cytoplasmic tyrosine kinase

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99
Q

Burkitt’s lymphoma associated gene

A

c-MYC Transcription factor

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100
Q

neuroblastoma associated gene

A

n-MYC Transcription factor

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101
Q

follicular lymphoma associated gene

A

BCL-2 Apoptosis regulator protein

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102
Q

MEN 2+3 gene

A

RET Tyrosine kinase receptor

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103
Q

RAS gene conditions

A

G-protein Many cancers especially pancreatic

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104
Q

erb-B2 associated cancer

A

erb-B2 (HER2/neu) Tyrosine kinase receptor Breast and ovarian cancer

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105
Q

ADH secreted from?

A

Synthesized in the supraoptic nuclei of the hypothalamus, released by the posterior pituitary

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106
Q

ADH function

A

Conserves body water Promotes water reabsorption in the collecting ducts of the kidneys by the insertion of aquaporin-2 channels

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107
Q

ADH regulation

A 
Increases secretion
extracellular fluid osmolality increase
volume decrease
pressure decrease
angiotensin II

Decreases secretion
extracellular fluid osmolality decrease
volume increase
temperature decrease
Diabetes insipidus (DI) is a condition characterised by either a deficiency of antidiuretic hormone, ADH, (cranial DI) or an insensitivity to antidiuretic hormone (nephrogenic DI)
Cranial DI can be treated by desmopressin, an analog of ADH

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108
Q

Di George syndrome cause

A

T-cell deficiency and dysfunction. It is an example of a microdeletion syndrome (deletion of a section of chromosome 22).

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109
Q

Di George syndrome features

A 
C - Cardiac abnormalities
A - Abnormal facies
T - Thymic aplasia
C - Cleft palate
H - Hypocalcaemia/ hypoparathyroidism (parathyroid gland hypoplasia)
22 - Caused by chromosome 22 deletion
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110
Q

what infection are patients with t-cell dysfunction at risk of

A

recurrent viral and fungal infections

e.g. cryptococcus

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111
Q

homocystinuria features

A

often patients have fine, fair hair
musculoskeletal: may be similar to Marfan’s - arachnodactyly etc
neurological patients may have learning difficulties, seizures
ocular: downwards (inferonasal) dislocation of lens
increased risk of arterial and venous thromboembolism
also malar flush, livedo reticularis

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112
Q

homocystinuria diagnosis

A

cyanide-nitroprusside test, which is also positive in cystinuria.

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113
Q

homocystinuria cause

A

rare autosomal recessive disease caused by a deficiency of cystathionine beta synthase. This results in severe elevations in plasma and urine homocysteine concentrations.

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114
Q

homocystinuria treatment

A

vitamin B6 (pyridoxine)

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115
Q

southern blotting detects

A

DNA

SNOW DROP

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116
Q

northern blotting detects

A

RNA

SNOW DROP

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117
Q

Western blotting detects

A

proteins

Uses gel electrophoresis to separate native proteins by 3-D structure
Examples include the confirmatory HIV test

SNOW DROP

118
Q

what is ELISA?

A

a type of biochemical assay used to detect antigens and antibodies
a colour changing enzyme is attached to the antibody if looking for an antigen and to an antigen if looking for an antibody
the sample therefore changes colour if the antigen or antibody is detected
an example includes the initial HIV test

119
Q

4 main types of membrane receptor

A
  • ligand gated ion channels
  • tyrosine kinase receptors
  • guanylate cyclase receptors
  • GPCRS
120
Q

ligand-gated ion channel receptors

A

generally mediate fast responses

e.g. nicotinic acetylcholine, GABA-A & GABA-C, glutamate receptors

121
Q

tyrosine kinase receptors

A

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

122
Q

guanylate cyclase receptors

A

contain intrinsic enzyme activity

e.g. atrial natriuretic factor, brain natriuretic peptide

123
Q

GPCRS

A

generally mediate slow transmission and affect metabolic processes
activated by a wide variety of extracellular signals e.g. Peptide hormones, biogenic amines (e.g. adrenaline), lipophilic hormones, light
7-helix membrane-spanning domains
consist of 3 main subunits: alpha, beta and gamma
the alpha subunit is linked to GDP.Ligand binding causes conformational changes to receptor, GDP is phosphorylated to GTP,and the alpha subunit is activated
G proteins are named according to the alpha subunit (Gs, Gi, Gq)

124
Q

what does Gs do?

A

Stimulates adenylate cyclase → increases cAMP → activates protein kinase A

Beta-1 receptors (epinephrine, norepinephrine, dobutamine)
• Beta-2 receptors (epinephrine, salbuterol)
• H2 receptors (histamine)
• D1 receptors (dopamine)
• V2 receptors (vasopressin)
• Receptors for ACTH, LH, FSH, glucagon, PTH, calcitonin, prostaglandins

125
Q

what does Gi do?

A

Inhibits adenylate cyclase → decreases cAMP → inhibits protein kinase A

M2 receptors (acetylcholine)
• Alpha-2 receptors (epinephrine, norephinephrine)
• D2 receptors (dopamine)
• GABA-B receptor

126
Q

what does Gq do?

A

Activates phospholipase C → splits PIP2 to IP3 & DAG → activates protein kinase C

Alpha-1 receptors (epinephrine, norepinephrine)
• H1 receptors (histamine)
• V1 receptors (vasopressin)
• M1, M3 receptors (acetylcholine)

127
Q

Type 1 hypersensitivity reaction

A

Antigen reacts with IgE bound to mast cells • Anaphylaxis

• Atopy (e.g. asthma, eczema and hayfever)

128
Q

Type 2 hypersensitivity reaction

A

IgG or IgM binds to antigen on cell surface • Autoimmune haemolytic anaemia
• ITP
• Goodpasture’s syndrome
• Pernicious anaemia
• Acute haemolytic transfusion reactions
• Rheumatic fever
• Pemphigus vulgaris / bullous pemphigoid

129
Q

type 3 hypersensitivity

A

Type III - Immune complex Free antigen and antibody (IgG, IgA) combine • Serum sickness
• Systemic lupus erythematosus
• Post-streptococcal glomerulonephritis
• Extrinsic allergic alveolitis (especially acute phase)

130
Q

Type 4 hypersensitivity reaction

A

T-cell mediated • Tuberculosis / tuberculin skin reaction
• Graft versus host disease
• Allergic contact dermatitis
• Scabies
• Extrinsic allergic alveolitis (especially chronic phase)
• Multiple sclerosis
• Guillain-Barre syndrome

131
Q

Type 5 hypersensitivity reaction

A

Antibodies that recognise and bind to the cell surface receptors.

This either stimulating them or blocking ligand binding • Graves’ disease
• Myasthenia gravis

132
Q

Ulnar nerve motor to…

A 
medial two lumbricals
aDductor pollicis
interossei
hypothenar muscles: abductor digiti minimi, flexor digiti minimi
flexor carpi ulnaris
133
Q

Down’s syndrome features

A

face: upslanting palpebral fissures, epicanthic folds, Brushfield spots in iris, protruding tongue, small low-set ears, round/flat face
flat occiput
single palmar crease, pronounced ‘sandal gap’ between big and first toe
hypotonia
congenital heart defects (40-50%, see below)
duodenal atresia
Hirschsprung’s disease

134
Q

Down’s syndrome cardiac defects

A

multiple cardiac problems may be present
endocardial cushion defect (most common, 40%, also known as atrioventricular septal canal defects)
ventricular septal defect (c. 30%)
secundum atrial septal defect (c. 10%)
tetralogy of Fallot (c. 5%)
isolated patent ductus arteriosus (c. 5%)

135
Q

later complications of Down’s

A 
subfertility: males are almost always infertile due to impaired spermatogenesis. Females are usually subfertile, and have an increased incidence of problems with pregnancy and labour
learning difficulties
short stature
repeated respiratory infections (+hearing impairment from glue ear)
acute lymphoblastic leukaemia
hypothyroidism
Alzheimer's disease
atlantoaxial instability
136
Q

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

A

Gaucher’s disease

137
Q

cherry red spots on macula, normal liver

A

Tay-Sachs disease Hexosaminidase A Accumulation of GM2 ganglioside within lysosomes. Key features include developmental delay, cherry red spot on the macula, liver and spleen normal size (cf. Niemann-Pick)

138
Q

cherry red spots on macula, enlarged liver

A

Niemann-Pick disease Sphingomyelinase Key features include hepatosplenomegaly, cherry red spot on the macula

139
Q

NNT

A

1 / (control event rate - experimental event rate)

OR

1 / Absolute Risk Reduction

140
Q

Turners syndrome features

A

short stature
shield chest, widely spaced nipples
webbed neck
bicuspid aortic valve (15%), coarctation of the aorta (5-10%)
primary amenorrhoea
cystic hygroma (often diagnosed prenatally)
high-arched palate
short fourth metacarpal
multiple pigmented naevi
lymphoedema in neonates (especially feet)
gonadotrophin levels will be elevated
hypothyroidism is much more common in Turner’s
horseshoe kidney: the most common renal abnormality in Turner’s syndrome

There is also an increased incidence of autoimmune disease (especially autoimmune thyroiditis) and Crohn’s disease

141
Q

turners syndrome pathophysiology

A

It is caused by either the presence of only one sex chromosome (X) or a deletion of the short arm of one of the X chromosomes. Turner’s syndrome is denoted as 45,XO or 45,X.

142
Q

down’s syndrome genetics

A

94% Nondisjunction
5% Robertsonian translocation
1% mosaicism

143
Q

Raised PAPP-A and abnormal nuchal translucency

A

Down’s syndrome

144
Q

trinucleotide repeat disorders

A 
Fragile X (CGG)
Huntington's (CAG)
myotonic dystrophy (CTG)
Friedreich's ataxia* (GAA)
spinocerebellar ataxia
spinobulbar muscular atrophy
dentatorubral pallidoluysian atrophy

*Friedreich’s ataxia is unusual in not demonstrating anticipation

145
Q

PTH actions

A

Increase calcium levels and decrease phosphate levels
Increases bone resorption
Immediate action on osteoblasts to increase ca2+ in extracellular fluid
Osteoblasts produce a protein signaling molecule that activate osteoclasts which cause bone resorption
Increases renal tubular reabsorption of calcium
Increases synthesis of 1,25(OH)2D (active form of vitamin D) in the kidney which increases bowel absorption of Ca2+
Decreases renal phosphate reabsorption

146
Q

1,25 dihydroxycholecalciferol effects

A

Increases plasma calcium and plasma phosphate
Increases renal tubular reabsorption and gut absorption of calcium
Increases osteoclastic activity
Increases renal phosphate reabsorption in the proximal tubule

147
Q

Calcitonin effects

A

Secreted by C cells of thyroid
Inhibits osteoclast activity
Inhibits renal tubular absorption of calcium

148
Q

Which drug for TB can cause burning in the feet?

A

Isoniazid therapy can cause a vitamin B6 deficiency causing peripheral neuropathy

149
Q

Vitamin B6 deficincy consequences

A

peripheral neuropathy

sideroblastic anaemia

150
Q

Noonan’s syndrome

A

‘male Turner’s’, Noonan syndrome is an autosomal dominant condition associated with a normal karyotype. It is thought to be caused by a defect in a gene on chromosome 12

As well as features similar to Turner’s syndrome (webbed neck, widely-spaced nipples, short stature, pectus carinatum and excavatum), a number of characteristic clinical signs may also be seen:
cardiac: pulmonary valve stenosis
ptosis
triangular-shaped face
low-set ears
coagulation problems: factor XI deficiency

151
Q

role of T helper cells

A

Involved in the cell-mediated immune response
Recognises antigens presented by MHC class II molecules
Expresses CD4
Also expresses CD3, TCR & CD28
Major source of IL-2
Mediates acute and chronic organ rejection

152
Q

role of cytotoxic T cells

A

Involved in the cell-mediated immune response
Recognises antigens presented by MHC class I molecules
Induce apoptosis in virally infected and tumour cells
Expresses CD8
Also expresses CD3, TCR
Mediates acute and chronic organ rejection

153
Q

role of B cells

A

Major cell of the humoral immune response
Acts as an antigen presenting cell
Mediates hyperacute organ rejection

154
Q

role of plasma cells

A

Differentiated from B cells

Produces large amounts of antibody specific to a particular antigen

155
Q

Wilson and Junger screening criteria

A
  1. The condition should be an important public health problem
  2. There should be an acceptable treatment for patients with recognised disease
  3. Facilities for diagnosis and treatment should be available
  4. There should be a recognised latent or early symptomatic stage
  5. The natural history of the condition, including its development from latent to declared disease should be adequately understood
  6. There should be a suitable test or examination
  7. The test or examination should be acceptable to the population
  8. There should be agreed policy on whom to treat
  9. The cost of case-finding (including diagnosis and subsequent treatment of patients) should be economically balanced in relation to the possible expenditure as a whole
  10. Case-finding should be a continuous process and not a ‘once and for all’ project
156
Q

Blood tests in DIC

A

prolonged clotting times, thrombocytopenia, decreased fibrinogen, increased fibrinogen degradation products

157
Q

Causes of DIC

A 
Infection
Malignancy
Trauma e.g. major surgery, burns, shock, dissecting aortic aneurysm
Liver disease
Obstetric complications
158
Q

Haemophillia inheritance

A

In X-linked recessive inheritance only males are affected. An exception to this seen in examinations are patients with Turner’s syndrome, who are affected due to only having one X chromosome. X-linked recessive disorders are transmitted by heterozygote females (carriers) and male-to-male transmission is not seen. Affected males can only have unaffected sons and carrier daughters.

Each male child of a heterozygous female carrier has a 50% chance of being affected whilst each female child of a heterozygous female carrier has a 50% chance of being a carrier.

The possibility of an affected father having children with a heterozygous female carrier is generally speaking extremely rare. However, in certain Afro-Caribbean communities G6PD deficiency is relatively common and homozygous females with clinical manifestations of the enzyme defect are seen.

159
Q

Cardiac cycle stages

A

0 Rapid depolarisation 1 Early repolarisation
2 Plateau
3 Final repolarisation
4 Restoration of ionic concentrations

160
Q

what causes phase 0 of cardiac cycle?

A

Rapid sodium influx

These channels automatically deactivate after a few ms

161
Q

what causes phase 1 of cardiac cycle?

A

Efflux of potassium

162
Q

what causes phase 2 of cardiac cycle?

A

Slow influx of calcium

163
Q

what causes phase 3 of cardiac cycle?

A

Efflux of potassium

164
Q

what causes phase 4 of cardiac cycle?

A

Resting potential is restored by Na+/K+ ATPase
There is slow entry of Na+ into the cell decreasing the potential difference until the threshold potential is reached, triggering a new action potential

165
Q

define penetrance

A

Penetrance describes the proportion of a population of individuals who carry a disease-causing allele who express the related disease phenotype.

166
Q

define expressivity

A

Expressivity describes the extent to which a genotype shows its phenotypic expression in an individual.

These phenomena are thought to be due to a number of factors, including:
Modifier genes
Environmental factors
Allelic variation

167
Q

PKU features

A

usually presents by 6 months e.g. with developmental delay
child classically has fair hair and blue eyes
learning difficulties
seizures, typically infantile spasms
eczema
‘musty’ odour to urine and sweat*

168
Q

PKU pathophysiology

A

autosomal recessive condition caused by a disorder of phenylalanine metabolism. This is usually due to defect in phenylalanine hydroxylase, an enzyme which converts phenylalanine to tyrosine. In a small number of cases the underlying defect is a deficiency of the tetrahydrobiopterin-deficient cofactor, e.g. secondary to defective dihydrobiopterin reductase. High levels of phenylalanine lead to problems such as learning difficulties and seizures. The gene for phenylalanine hydroxylase is located on chromosome 12. The incidence of PKU is around 1 in 10,000 live births.

169
Q

PKU diagnosis

A

Guthrie test: the ‘heel-prick’ test done at 5-9 days of life - also looks for other biochemical disorders such as hypothyroidism
hyperphenylalaninaemia
phenylpyruvic acid in urine

170
Q

PKU management

A

poor evidence base to suggest strict diet prevents learning disabilities
dietary restrictions are however important during pregnancy as genetically normal fetuses may be affected by high maternal phenylalanine levels

171
Q

Bohr effect

A

increasing acidity (or pCO2) means O2 binds less well to Hb

172
Q

Haldane effect

A

increase pO2 means CO2 binds less well to Hb

173
Q

main functioning component of surfactant

A

dipalmitoyl phosphatidylcholine (DPPC) which reduces alveolar surface tension.

174
Q

surfactant released by…

A

type 2 pneumocytes

175
Q

Relative risk reduction

A

(EER - CER) / CER

176
Q

Relative risk ratio

A

EER / CER

177
Q

corneal reflexes nerves

A

Ophthalmic nerve (V1) Facial nerve (VII)

178
Q

Jaw jerk reflex

A

Mandibular nerve (V3) Mandibular nerve (V3)

179
Q

Gag reflex nerves

A

Glossopharyngeal nerve (IX) Vagal nerve (X)

180
Q

carotid sinus nerve

A

Glossopharyngeal nerve (IX) Vagal nerve (X)

181
Q

pupillary light reflex nerve

A

Optic nerve (II) Oculomotor nerve (III)

182
Q

lacrimation reflex nerves

A

Ophthalmic nerve (V1) Facial nerve (VII)

183
Q

define p value

A

is the probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true

184
Q

Alkaptonuria

A

Alkaptonuria (ochronosis) is a rare autosomal recessive disorder of phenylalanine and tyrosine metabolism caused by a lack of the enzyme homogentisic dioxygenase (HGD) which results in a build-up of toxic homogentisic acid. The kidneys filter the homogentisic acid (hence black urine) but eventually it accumulates in cartilage and other tissues.

Alkaptonuria is generally a benign and often asymptomatic condition. Possible features include:
pigmented sclera
urine turns black if left exposed to the air
intervertebral disc calcification may result in back pain
renal stones

Treatment
high-dose vitamin C
dietary restriction of phenylalanine and tyrosine

185
Q

nitric oxide effects

A

acts on guanylate cyclase leading to raised intracellular cGMP levels and therefore decreasing Ca2+ levels
vasodilation, mainly venodilation
inhibits platelet aggregation

186
Q

clinical relevance NO

A

underproduction of NO is implicated in hypertrophic pyloric stenosis
lack of NO is thought to promote atherosclerosis
in sepsis increased levels of NO contribute to septic shock
organic nitrates (metabolism produces NO) is widely used to treat cardiovascular disease (e.g. angina, heart failure)
sildenafil is thought to potentiate the action of NO on penile smooth muscle and is used in the treatment of erectile dysfunctions

187
Q

Linear regression

A

In contrast to the correlation coefficient, linear regression may be used to predict how much one variable changes when a second variable is changed. A regression equation may be formed, y = a + bx, where
y = the variable being calculated
a = the intercept value, when x = 0
b = the slope of the line or regression coefficient. Simply put, how much y changes for a given change in x
x = the second variable

188
Q

IgG

A

75% Monomer • Enhance phagocytosis of bacteria and viruses
• Fixes complement and passes to the fetal circulation
• Most abundant isotype in blood serum

GAMDE

189
Q

IgA

A

15% Monomer/ dimer • IgA is the predominant immunoglobulin found in breast milk. It is also found in the secretions of digestive, respiratory and urogenital tracts and systems
• Provides localized protection on mucous membranes
• Most commonly produced immunoglobulin in the body (but blood serum concentrations lower than IgG
.)
• Transported across the interior of the cell via transcytosis

190
Q

IgM

A

10% Pentamer • First immunoglobulins to be secreted in response to an infection
• Fixes complement but does not pass to the fetal circulation
• Anti-A, B blood antibodies (note how they cannot pass to the fetal circulation, which could of course result in haemolysis)
Pentamer when secreted

191
Q

IgD

A

1% Monomer • Role in immune system largely unknown

• Involved in activation of B cells

192
Q

IgE

A

0.1% Monomer • Mediates type 1 hypersensitivity reactions
• Binds to Fc receptors found on the surface of mast cells and basophils
• Provides immunity to parasites such as helminths
• Least abundant isotype in blood serum

193
Q

types of T cells

A

Th1 and Th2

194
Q

Th1 cells do what

A

involved in the cell-mediated response and delayed (type IV) hypersensitivity
secrete IFN-gamma, IL-2, IL-3

195
Q

Th2 cells do what

A

involved in mediating humoral (antibody) immunity
e.g. stimulating production of IgE in asthma
secrete IL-4, IL-5, IL-6, IL-10, IL-13

196
Q

Endothelin

A

Endothelin is a potent, long-acting vasoconstrictor and bronchoconstrictor. It is secreted initially as a prohormone by the vascular endothelium and later converted to ET-1 by the action of endothelin converting enzyme. It acts via interaction with a G-protein linked to phospholipase C leading to calcium release. Endothelin is thought to be important in the pathogenesis of many diseases including primary pulmonary hypertension (endothelin antagonists are now used), cardiac failure, hepatorenal syndrome and Raynaud’s

Promotes release
angiotensin II
ADH
hypoxia
mechanical shearing forces

Inhibits release
nitric oxide
prostacyclin

Raised levels in
MI
heart failure
ARF
asthma
primary pulmonary hypertension
197
Q

funnel plot use

A

demonstrate the existence of publication bias in meta-analyses. Funnel plots are usually drawn with treatment effects on the horizontal axis and study size on the vertical axis.

Interpretation
a symmetrical, inverted funnel shape indicates that publication bias is unlikely
conversely, an asymmetrical funnel indicates a relationship between treatment effect and study size. This indicates either publication bias or a systematic difference between smaller and larger studies (‘small study effects’)

198
Q

Immunological changes in HIV

A 
reduction in CD4 count
increase B2-microglobulin
decreased IL-2 production
polyclonal B-cell activation
decrease NK cell function
reduced delayed hypersensitivity responses
199
Q

5 epidermal layers

A

Stratum corneum Flat, dead, scale-like cells filled with keratin
Continually shed
Stratum lucidum Clear layer - present in thick skin only
Stratum granulosum Cells form links with neighbours
Stratum spinosum Squamous cells begin keratin synthesis
Thickest layer of epidermis
Stratum germinativum The basement membrane - single layer of columnar epithelial cells
Gives rise to keratinocytes
Contains melanocytes

Come (corneum)
Let's (lucidum)
Get (granulosum)
Sun (spinosum)
Burnt (basale)
200
Q

Skeletal muscle contraction

A

action potential reaches the neuromuscular junction, causing a calcium ion influx through voltage-gated calcium channels
the calcium influx causes the release of acetylcholine into the extracellular space
the acetylcholine activates nicotinic acetylcholine receptors causing an influx of sodium, triggering an action potential
the action potential spreads through the T-tubules
the depolarization activates L-type voltage-dependent calcium channels (dihydropyridine receptors) in the T-tubule membrane, which are close to calcium-release channels (ryanodine receptors) in the adjacent sarcoplasmic reticulum
this causes the sarcoplasmic reticulum to release calcium
calcium binds to troponin C (found on actin-containing thin filaments) causing a conformational change, allowing tropomyosin to move, unblocking the binding sites
myosin binds to the newly released binding site releasing ADP, pulling the Z bands towards each other
ATP binds to myosin, releasing actin

201
Q

Fabry’s disease

A

Overview
X-linked recessive
deficiency of alpha-galactosidase A

Features
burning pain/paraesthesia in childhood
angiokeratomas
lens opacities
proteinuria
early cardiovascular disease
202
Q

Leptin

A

Leptin is 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.

Leptin stimulates the release of melanocyte-stimulating hormone (MSH) and corticotrophin-releasing hormone (CRH). Low levels of leptin stimulates the release of neuropeptide Y (NPY)

203
Q

Ghrelin

A

Where as leptin induces satiety, ghrelin stimulates hunger. It is produced mainly by the P/D1 cells lining the fundus of the stomach and epsilon cells of the pancreas. Ghrelin levels increase before meals and decrease after meals

204
Q

odds ratio

A

ad/bc

205
Q

causes of metabolic alkalosis

A 
vomiting / aspiration (e.g. peptic ulcer leading to pyloric stenos, nasogastric suction)
diuretics
liquorice, carbenoxolone
hypokalaemia
primary hyperaldosteronism
Cushing's syndrome
Bartter's syndrome
206
Q

mechanism of metabolic alkalosis

A 
activation of renin-angiotensin II-aldosterone (RAA) system is a key factor
aldosterone causes reabsorption of Na+ in exchange for H+ in the distal convoluted tubule
ECF depletion (vomiting, diuretics) → Na+ and Cl- loss → activation of RAA system → raised aldosterone levels
in hypokalaemia, K+ shift from cells → ECF, alkalosis is caused by shift of H+ into cells to maintain neutrality
207
Q

superiority trial

A

superiority: whilst this may seem the natural aim of a trial one problem is the large sample size needed to show a significant benefit over an existing treatment

208
Q

equivalence trial

A

an equivalence margin is defined (-delta to +delta) on a specified outcome. If the 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

209
Q

non-inferiority trial

A

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

210
Q

drugs contraindicated in breast feeding

A 
antibiotics: ciprofloxacin, tetracycline, chloramphenicol, sulphonamides
psychiatric drugs: lithium, benzodiazepines
aspirin
carbimazole
methotrexate
sulfonylureas
cytotoxic drugs
amiodarone
211
Q

skewed distribution

A

alphabetical order: mean - median - mode

‘>’ for positive, ‘

212
Q

function of microtubules

A

Microtubules are components of the cytoskeleton of the cytoplasm. They help guide movement during intracellular transport and also help bind internal organelles. Microtubules are found in all cells except red blood cells.

213
Q

microtubules structure

A

cylindrical structure composed of alternating α and β tubulin subunits which polymerize to form protofilaments
microtubules are polarized, having a positive and negative end

214
Q

molecular transport microtubules

A

attachment proteins called dynein and kinesin move up and down the microtubules facilitating the movement of various organelles around the cell
dynein moves in a retrograde fashion, down the the microtubule towards the centre of the cell (+ve → -ve)
kinesin moves in an anterograde fashion, up the microtubule away from the centre, towards the periphery (-ve → +ve)

215
Q

EEG theta waves

A

Non-REM stage 1 (N1) Theta waves Light sleep

Transition to this stage be associated with hypnic jerks

216
Q

N2 sleep stage on EEG

A

Non-REM stage 2 (N2) Sleep spindles + K-complexes Deeper sleep
Represents around 50% of total sleep

217
Q

delta waves on EEG

A

Non-REM stage 3 (N3) Delta waves Deep sleep

Parasomnias such as night terrors, nocturnal enuresis, sleepwalking

218
Q

REM sleep on EEG

A

REM Beta-waves Dreaming occurs

Loss of muscle tone, erections

219
Q

stages of sleep with EEG findings

A

N1 → N2 → N3 → REM

Theta → Sleep spindles/K-complexes → Delta → Beta

The Sleep Doctor’s Brain

220
Q

what is interferon alpha

A

produced by leucocytes
antiviral action
useful in hepatitis B & C, Kaposi’s sarcoma, metastatic renal cell cancer, hairy cell leukaemia
adverse effects include flu-like symptoms and depression

221
Q

what is interferon beta

A

produced by fibroblasts
antiviral action
reduces the frequency of exacerbations in patients with relapsing-remitting MS

222
Q

what is interferon gamma

A

predominately natural killer cells. Also by T helper cells
weaker antiviral action, more of a role in immunomodulation particularly macrophage activation
may be useful in chronic granulomatous disease and osteopetrosis

223
Q

interferon binding sites

A

FN-alpha and IFN-beta bind to type 1 receptors whilst IFN-gamma binds only to type 2 receptors.

224
Q

what is cerebral perfusion pressure

A

net pressure gradient causing blood flow to the brain. The CPP is tightly autoregulated to maximise cerebral perfusion. A sharp rise in CPP may result in a rising ICP, a fall in CPP may result in cerebral ischaemia. It may be calculated by the following equation:

CPP= Mean arterial pressure - Intra cranial pressure

Following trauma, the CPP has to be carefully controlled and the may require invasive monitoring of the ICP and MAP.

225
Q

standard deviation

A

square root variance

226
Q

achondroplasia genetics

A

Achondroplasia is an autosomal dominant disorder associated with short stature. It is caused by a mutation in the fibroblast growth factor receptor 3 (FGFR-3) gene.

In most cases (approximately 70%) it occurs as a sporadic mutation. The main risk factor is advancing parental age at the time of conception. Once present it is typically inherited in an autosomal dominant fashion.

227
Q

achndroplasia features

A

short limbs (rhizomelia) with shortened fingers (brachydactyly)
large head with frontal bossing and narrow foramen magnum
midface hypoplasia with a flattened nasal bridge
‘trident’ hands
lumbar lordosis

228
Q

what is williams syndrome

A

inherited neurodevelopmental disorder caused by a microdeletion on chromosome 7

229
Q

features williams syndrome

A 
elfin-like facies
characteristic like affect - very friendly and social
learning difficulties
short stature
transient neonatal hypercalcaemia
supravalvular aortic stenosis
230
Q

diagnosis of williams syndrome

A

Diagnosis is made by FISH studies

231
Q

posterior to right kidney

A

Quadratus lumborum, diaphragm, psoas major, transversus abdominis

232
Q

posterior to left kidney

A

Quadratus lumborum, diaphragm, psoas major, transversus abdominis

233
Q

anterior to right kidney

A

Hepatic flexure of colon

234
Q

anterior to left kidney

A

Stomach, Pancreatic tail

235
Q

superior to right kidney

A

Liver, adrenal gland

236
Q

superior to left kidney

A

Spleen, adrenal gland

237
Q

structure of renal hilum

A

The renal vein lies most anteriorly, then renal artery (it is an end artery) and the ureter lies most posterior.

238
Q

contents popliteal fossa

A 
Popliteal artery and vein
Small saphenous vein
Common peroneal nerve
Tibial nerve
Posterior cutaneous nerve of the thigh
Genicular branch of the obturator nerve
Lymph nodes
239
Q

histopathology acute tubular necrosis

A

tubular epithelium necrosis: loss of nuclei and detachment of tubular cells from the basement membrane
dilatation of the tubules may occur
necrotic cells obstruct the tubule lumen

240
Q

phases of anaphase

A

anaphase A: cohesins that bind sister chromatids together are cleaved, followed by shortening of the kinetochore microtubules which pulls the daughter chromosomes to opposite ends of the cell
anaphase B: polar microtubules push against each other, causing the cell to elongate

241
Q

what does troponin C bind to

A

calcium ions

242
Q

what does troponin T bind to

A

tropomyosin

243
Q

what does troponin I bind to

A

actin to hold toponin-tropomyosin complex in place

244
Q

what is myosin

A

the thick component of muscle fibres. Actin slides along myosin to generate muscle contraction.

245
Q

3 places that control respiration

A

central regulatory centres
central and peripheral chemoreceptors
pulmonary receptors

246
Q

central regulatory centres

A 
medullary respiratory centre
apneustic centre (lower pons)
pneumotaxic centre (upper pons)
247
Q

central and peripheral chemoreceptors

A

central: raised [H+] in ECF stimulates respiration
peripheral: carotid + aortic bodies, respond to raised pCO2 & [H+], lesser extent low pO2

248
Q

pulmonary receptors

A

stretch receptors, lung distension causes slowing of respiratory rate (Hering-Bruer reflex)
irritant receptor, leading to bronchoconstriction
juxtacapillary receptors, stimulated by stretching of the microvasculature

249
Q

most common renal stone

A

alcium oxalate Hypercalciuria is a major risk factor (various causes)
Hyperoxaluria may also increase risk
Hypocitraturia increases risk because citrate forms complexes with calcium making it more soluble
Stones are radio-opaque (though less than calcium phosphate stones)
Hyperuricosuria may cause uric acid stones to which calcium oxalate binds 85%

250
Q

cystine stones

A

Inherited recessive disorder of transmembrane cystine transport leading to decreased absorption of cystine from intestine and renal tubule
Multiple stones may form
Relatively radiodense because they contain sulphur 1%

251
Q

uric acid stones

A

Uric acid is a product of purine metabolism
May precipitate when urinary pH low
May be caused by diseases with extensive tissue breakdown e.g. malignancy
More common in children with inborn errors of metabolism
Radiolucent 5-10%

252
Q

calcium phosphate stones

A

May occur in renal tubular acidosis, high urinary pH increases supersaturation of urine with calcium and phosphate
Renal tubular acidosis types 1 and 3 increase risk of stone formation (types 2 and 4 do not)
Radio-opaque stones (composition similar to bone) 10%

253
Q

struvite stones

A

Stones formed from magnesium, ammonium and phosphate
Occur as a result of urease producing bacteria (and are thus associated with chronic infections)
Under the alkaline conditions produced, the crystals can precipitate
Slightly radio-opaque 2-20%

254
Q

prolactin function

A

Stimulates breast development (both initially and further hyperplasia during pregnancy)
Stimulates milk production

It decreases GnRH pulsatility at the hypothalamic level and to a lesser extent, blocks the action of LH on the ovary or testis.

255
Q

prolactin regulation

A

Prolactin secretion is under constant inhibition by dopamine

Increases secretion
thyrotropin releasing hormone
pregnancy
oestrogen
breastfeeding
sleep
stress
drugs e.g. metoclopramide, antipsychotics

Decreases secretion
dopamine
dopaminergic agonists

256
Q

riboflavin deficiency

A

Riboflavin is a cofactor of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) and is important in energy metabolism.

Consequences of riboflavin deficiency:
angular cheilitis

257
Q

iron absorption

A

upper small intestine especially the duodenum
about 10% of dietary iron absorbed
Fe2+ (ferrous iron) much better absorbed than Fe3+ (ferric iron)
absorption is regulated according to body’s need
increased by vitamin C, gastric acid
decreased by proton pump inhibitors, tetracycline, gastric achlorhydria, tannin (found in tea)

258
Q

iron distribution

A 
total body iron = 4g
haemoglobin = 70%
ferritin and haemosiderin = 25%
myoglobin = 4%
plasma iron = 0.1%
259
Q

what is fabry disease?

A

Overview
X-linked recessive
deficiency of alpha-galactosidase A

Features
burning pain/paraesthesia in childhood
angiokeratomas
lens opacities
proteinuria
early cardiovascular disease
260
Q

primary hyperparathyroidism

A

PTH (Elevated)
Ca2+ (Elevated)
Phosphate (Low)
Urine calcium : creatinine clearance ratio > 0.01
May be asymptomatic if mild
Recurrent abdominal pain (pancreatitis, renal colic)
Changes to emotional or cognitive state
Most cases due to solitary adenoma (80%), multifocal disease occurs in 10-15% and parathyroid carcinoma in 1% or less

261
Q

secondary hyperparathyroidism

A

PTH (Elevated)
Ca2+ (Low or normal)
Phosphate (Elevated)
Vitamin D levels (Low)
May have few symptoms
Eventually may develop bone disease, osteitis fibrosa cystica and soft tissue calcifications
Parathyroid gland hyperplasia occurs as a result of low calcium, almost always in a setting of chronic renal failure

262
Q

tertiary hyperparathyroidism

A 
Ca2+ (Normal or high)
PTH (Elevated)
Phosphate levels (Decreased or Normal)
Vitamin D (Normal or decreased)
Alkaline phosphatase (Elevated)
Metastatic calcification
Bone pain and / or fracture
Nephrolithiasis
Pancreatitis
Occurs as a result of ongoing hyperplasia of the parathyroid glands after correction of underlying renal disorder, hyperplasia of all 4 glands is usually the cause
263
Q

indications for surgery in primary hyperparathyroidism

A

Elevated serum Calcium > 1mg/dL above normal
Hypercalciuria > 400mg/day
Creatinine clearance < 30% compared with normal
Episode of life threatening hypercalcaemia
Nephrolithiasis
Age < 50 years
Neuromuscular symptoms
Reduction in bone mineral density of the femoral neck, lumbar spine, or distal radius of more than 2.5 standard deviations below peak bone mass (T score lower than -2.5)

264
Q

indications for surgery in secondary hyperparathyroidism

A

Bone pain
Persistent pruritus
Soft tissue calcifications

265
Q

treatment for tertiary hyperparathyroidism

A

The presence of an autonomously functioning parathyroid gland may require surgery. If the culprit gland can be identified then it should be excised. Otherwise total parathyroidectomy and re-implantation of part of the gland may be required.

266
Q

growth hormone source

A

Anterior pituitary: Somatotrophs comprise 50% of the cells of the anterior pituitary gland

267
Q

growth hormone function

A

Postnatal growth and development
Numerous actions on protein, carbohydrate and fat metabolism (including increasing lipolysis and gluconeogenesis) Mechanism of action
acts on a transmembrane receptor for growth factor
binding of GH to the receptor leads to receptor dimerization
acts directly on tissues and also indirectly via insulin-like growth factor 1 (IGF-1), primarily secreted by the liver

268
Q

growth hormone regulation

A 
Increases secretion
growth hormone releasing hormone (GHRH): released in pulses by the hypothalamus
fasting
exercise
sleep (particularly delta sleep)

Decreases secretion
glucose
somatostatin (itself increased by somatomedins, circulating insulin-like growth factors, IGF-1 and IGF-2)
Conditions associated with GH disorders
excess GH: acromegaly
GH deficiency: resulting in short stature

269
Q

antibody regions

A

Fab region: antigen-binding fragment - the region that binds to antigens
Fc region: fragment crystallizable region - the tail region of an antibody that interacts with cell surface receptors

270
Q

leukotriene function

A

mediators of inflammation and allergic reactions
cause bronchoconstriction, mucous production
increase vascular permeability, attract leukocytes
leukotriene D4 has been identified as the SRS-A (slow reacting substance of anaphylaxis)

271
Q

leukotriene production

A

secreted by leukocytes
formed from arachidonic acid by action of lipoxygenase
it is thought that the NSAID induced bronchospasm in asthmatics is secondary to the express production of leukotrienes due to the inhibition of prostaglandin synthetase

272
Q

renin effects

A

secreted by juxtaglomerular cells and hydrolyses angiotensinogen to produce angiotensin I

273
Q

stimulating renin release

A 
hypotension causing reduced renal perfusion
hyponatraemia
sympathetic nerve stimulation
catecholamines
erect posture
274
Q

factors reducing renin secretion

A

drugs: beta-blockers, NSAIDs

275
Q

what is lesch Nyhan syndrome?

A

known as juvenile gout, is characterized by hyperuricemia. It is a genetic condition with an X-linked pattern of inheritance. It is caused by a defect in the purine salvage pathway due to the absence of the hypoxanthine-guanine phosphoribosyltransferase (HGPRT) enzyme which catalyzes the conversion of hypoxanthine to inosine monophosphate (IMP) and guanine to guanosine monophosphate (GMP). The consequence is an accumulation of uric acid. The typical findings supporting this diagnosis in this patient is the aggressive behavior, self-mutilation, intellectual impairment as well as laboratory finding of hyperuricemia.

276
Q

what is nyacin?

A

Niacin is a water soluble vitamin of the B complex group. It is a precursor to NAD+ and NADP+ and hence plays an essential metabolic role in cells.

Biosynthesis
Hartnup’s disease: hereditary disorder which reduces absorption of tryptophan
carcinoid syndrome: increased tryptophan metabolism to serotonin

Consequences of niacin deficiency:
pellagra: dermatitis, diarrhoea, dementia

277
Q

what is prader-willi syndrome?

A

rader-Willi syndrome is an example of genetic imprinting where the phenotype depends on whether the deletion occurs on a gene inherited from the mother or father:
Prader-Willi syndrome if gene deleted from father
Angelman syndrome if gene deleted from mother

Prader-Willi syndrome is associated with the absence of the active Prader-Willi gene on the long arm of chromosome 15. This may be due to:
microdeletion of paternal 15q11-13 (70% of cases)
maternal uniparental disomy of chromosome 15

Features
hypotonia during infancy
dysmorphic features
short stature
hypogonadism and infertility
learning difficulties
childhood obesity
behavioural problems in adolescence
278
Q

prader willi v angelman

A

Deletion of chromosome 15
Prader-Willi - paternal
Angelman syndrome - maternal

279
Q

phases of cardiac action potential

A

0 Rapid depolarisation Rapid sodium influx
These channels automatically deactivate after a few ms

1 Early repolarisation Efflux of potassium

2 Plateau Slow influx of calcium

3 Final repolarisation Efflux of potassium

4 Restoration of ionic concentrations Resting potential is restored by Na+/K+ ATPase
There is slow entry of Na+ into the cell decreasing the potential difference until the threshold potential is reached, triggering a new action potential

280
Q

pre-test probability

A

The proportion of people with the target disorder in the population at risk at a specific time (point prevalence) or time interval (period prevalence)

281
Q

post-test probability

A

The proportion of patients with that particular test result who have the target disorder

282
Q

pre-test odds

A

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)

283
Q

post-test odds

A

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)

284
Q

organisation of adrenal cortex

A 
zona glomerulosa (on outside): mineralocorticoids, mainly aldosterone
zona fasciculata (middle): glucocorticoids, mainly cortisol
zona reticularis (on inside): androgens, mainly dehydroepiandrosterone (DHEA)
285
Q

renin

A

an enzyme that is released by the renal juxtaglomerular cells in response to reduced renal perfusion
other factors that stimulate renin secretion include hyponatraemia, sympathetic nerve stimulation
hydrolyses angiotensinogen to form angiotensin I

286
Q

angiotensin 2

A

angiotensin-converting enzyme (ACE) in the lungs converts angiotensin I → angiotensin II
angiotensin II has a wide variety of actions:
causes vasoconstriction of vascular smooth muscle leading to raised blood pressure and vasoconstriction of efferent arteriole of the glomerulus → increased filtration fraction (FF) to preserve GFR. Remember that FF = GFR / renal plasma flow
stimulates thirst (via the hypothalamus)
stimulates aldosterone and ADH release
increases proximal tubule Na+/H+ activity

287
Q

aldosterone

A

released by the zona glomerulosa in response to raised angiotensin II, potassium, and ACTH levels
causes retention of Na+ in exchange for K+/H+ in distal tubule

288
Q

phas 1 trial

A

Determines pharmacokinetics and pharmacodynamics and side-effects prior to larger studies Conducted on healthy volunteers

289
Q

phase 2 trials

A

Assess efficacy + dosage Involves small number of patients affected by particular disease

May be subdivided into
IIa - assesses optimal dosing
IIb - assesses efficacy

290
Q

phase 3 trials

A

Assess effectiveness Typically involves 100-1000’s of people, often as part of a randomised controlled trial, comparing new treatment with established treatments

291
Q

phase 4 trials

A

Postmarketing surveillance Monitors for long-term effectiveness and side-effects

MRCP (7 decks)

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