Clinical sciences

Question 1

What are funnel plots used for?

Answer 1

Used to demonstrate publication bias in meta analysases

Question 2

How do you interpret funnel plots?

Answer 2

Symmetrical, inverted funnel shape - pub bias unlikely

asymmetrical funnel - relationship present between treatment effect and study size –> publication bias or systematic difference between smaller and larger studies (small study effects)

Question 3

acending loop of henle - what can and cant get through?

Answer 3

Impermeable to water

Highly permeable to Na and Cl

Question 4

early-onset breast cancer, sarcoma and leukaemia

Condition? gene?

Answer 4

Li-Fraumeni syndrome - p53 mutation

Question 5

What is p53 gene for?

Answer 5

Crucial role in cell cycle - prevents entery into S phase until DNA has been checked and repaired

May also regulate apoptosis

Question 6

Which pneumocytes secrete surfactant?

Answer 6

Pneumocyte type 2 - can differentiate into type 1 during lung damage

Question 7

Difference between cranial and nephrogenic DI

Answer 7

Cranial - deficiency of ADH

Nephrogenic - insensitivity to ADH

Question 8

Where does ADH act and what does it do?

Answer 8

ADH promotes water reabsorption via insertion of aquaporin 2 channels in collect ducts

Question 9

What triggers release of ADH?

Answer 9

extracellular fluid osmolality increase
volume decrease
pressure decrease
angiotensin II

Question 10

What reduces secretion of ADH?

Answer 10

extracellular fluid osmolality decrease
volume increase
temperature decrease

Question 11

C1 inhibitor (C1-INH) protein deficiency - consequence?

Answer 11

causes hereditary angioedema
C1-INH is a multifunctional serine protease inhibitor

probable mechanism is uncontrolled release of bradykinin resulting in oedema of tissues

Question 12

C1q, C1rs, C2, C4 deficiency (classical pathway components) - consequence?

Answer 12

predisposes to immune complex disease
e.g. SLE, Henoch-Schonlein Purpura

Question 13

C3 deficiency - consequence?

Answer 13

causes recurrent bacterial infections

Question 14

C5 deficiency - consequence?

Answer 14

predisposes to Leiner disease

recurrent diarrhoea, wasting and seborrhoeic dermatitis

Question 15

C5-9 deficiency - consequence?

Answer 15

encodes the membrane attack complex (MAC)

particularly prone to Neisseria meningitidis infection

Question 16

What diseases is endothelin involved in?

Answer 16

primary pulmonary hypertension (endothelin antagonists are now used),

cardiac failure,

hepatorenal syndrome

and Raynaud’s.

Question 17

Calculation of absolute risk reduction?

Answer 17

Absolute risk reduction = (Control event rate) - (Experimental event rate)

Question 18

Where in nephron does majority of glucose reabsorption occur?

Answer 18

Proximal convoluted tubule

Question 19

What is the genetic phenomenon of anticipation? Which disorders are more likley to experience this?

Answer 19

earlier onset in successive generations

Particularly present in trinucleotide repeat disorders

Question 20

Most common cause of Down Syndrome (genetically)

Answer 20

Nondisjunction

Question 21

prenatal tests showing low circulating levels of pregnancy-associated plasma protein-A (PAPP-A) and an abnormal nuchal translucency screening test

Diagnosis?

Answer 21

Downs syndrome

Question 22

Examples of mitochondrially inherited disease?

Answer 22

Leber’s optic atrophy
symptoms typically develop at around the age of 30 years
central scotoma → loss of colour vision → rapid onset of significant visual impairment

MELAS syndrome: mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes

MERRF syndrome: myoclonus epilepsy with ragged-red fibres

Kearns-Sayre syndrome: onset in patients < 20 years old, external ophthalmoplegia, retinitis pigmentosa. Ptosis may be seen

sensorineural hearing loss

Question 23

Children of fathers with mitochondrialy inherited disease?

Answer 23

For a man with mitochondrial disease, none of his children will inherit the condition

Question 24

What is Gaucher’s disease? How does it present?

Answer 24

Gaucher’s disease is an autosomal recessive disease and it is the most common lipid storage disorder

Leads to accumulation of glucocerebrosidase in brain, liver and spleen

Present with hepatosplenomegaly and aseptic necrosis of femur

Question 25

Which metabolic disorder causes:
Developmental delay
Cherry red spot on macula
+- hepatosplenomegaly

Answer 25

If no hepatosplenomegaly - Tay-Sachs disease

If hepatospenomegaly - Niemann-Pick disease

Question 26

Most common cardiac and renal abnormalities in Turner’s?

Answer 26

Cardiac - Biscuspid aortic valve (15%), coarctation of aorta (5-10%)

Increased risk of aortic dilatation and dissection

Renal - horseshoe kidney

Question 27

What does specificity and sensitivity mean?

Answer 27

Specificity - Proportion of patients without the condition who have a negative test result
TN / (TN + FP)

Sensitivity - Proportion of patients with the condition who have a positive test result
Sensitivity = TP / (TP + FN )

Question 28

What is lead time bias?

Answer 28

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

Question 29

HLA DR3 is associated with which conditions?

Answer 29

dermatitis herpetiformis
Sjogren’s syndrome
primary biliary cirrhosis

T1DM (More strongly associated with DR4)

Question 30

How to calculate NTT?

Answer 30

NNT = 1 / Absolute Risk Reduction

Question 31

Short stature + primary amenorrhoea

Diagnosis?

Answer 31

Turners syndrome

Question 32

What are the parametric tests and non-parametric tests? When to use which?

Answer 32

Parametric - normally distributed data

Parametric tests:
- Students t test (paired v unpaired - single group of patients if paired)
- Pearsons product moment coefficient - correlated

Non-parametric tests
- Mann Whitney U test
- Wilcoxon signed rank test
- Chi-squared test
- Spearman, Kendall rank - correlation

Question 33

Which statistical test to use when:
comparing ordinal, interval, or ratio scales of unpaired data

Answer 33

Mann-Whitney U

Question 34

Which statistical test to use when:

comparing two sets of observations on a single sample, e.g. a ‘before’ and ‘after’ test on the same population following an intervention

Answer 34

Wilcoxon signed rank

Question 35

Which statistical test to use when:
Comparing proportions or percentages e.g. compares the percentage of patients who improved following two different interventions

Answer 35

Chi-squared

Question 36

Karyotype in Turners?

Answer 36

45 XO