2007 Paper A Flashcards Preview

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Flashcards in 2007 Paper A Deck (70):
1

The growth promoting effects of Growth Hormone (GH) are mostly mediated by which of the following?

A. Growth hormone releasing hormone.
B. IGF1 (Insulin-like Growth Factor One).
C. IGF2 (Insulin-like Growth Factor Two).
D. IGFBP3 (Insulin-like Growth Factor Binding Protein Three).
E. Insulin.

B. IGF1 (Insulin-like Growth Factor One).

2

Malrotation with midgut volvulus is a potentially life threatening condition in otherwise healthy infants. Which of the following best describes the normal rotation of the bowel that occurs during embryogenesis?
A. Clockwise 180 degrees.
B. Clockwise 270 degrees.
C. Counterclockwise 90 degrees.
D. Counterclockwise 180 degrees.
E. Counterclockwise 270 degrees.

E. Counterclockwise 270 degrees.

3

A three-year-old child undergoes cardiac catheterization. The saturations obtained in room air during the procedure are as follows:

Superior vena cava 75% 
Right atrium 75%
Inferior vena cava 75%
Right ventricle 75%
Main pulmonary artery 87%
Left ventricle 99%
Aorta 99%

The most likely cardiac abnormality that this child has is:
A. atrial septal defect.
B. atrial septal defect with partial anomalous pulmonary venous drainage.
C. patent ductus arteriosus.
D. ventricular septal defect.
E. ventricular septal defect with Eisenmenger’s complex.

C. patent ductus arteriosus.

4

In an X-linked disorder which has no effect on reproductive fitness or life expectancy, the expected ratio of affected (hemizygous) males to carrier (heterozygous) females is closest to:
A. 1:3.
B. 1:2.
C. 1:1.
D. 2:1.
E. 3:1.

B. 1:2.

5

Which biochemical abnormality is most consistently found in infants subjected to severe environmental deprivation?
A. Decreased cortisol.
B. Hyperglycaemia.
C. Hypoglycaemia.
D. Hypothyroidism.
E. Increased cortisol.

E. Increased cortisol.

6

At what age does physical aggression peak across populations? 

A.1-2 years.
B.2-3 years.
C.5-6 years.
D. 8-10 years.
E.14-18 years.




 

B.2-3 years

7

A nine-year-old girl is referred from the surgical clinic, where evaluation of recurrent abdominal pain included the following blood film. Her mother required cholecystectomy for gallstones at 19 years of age, and her maternal grandfather is thought to have had a splenectomy as a young adult.

Which of the following tests is likely to be abnormal?
A. Acid serum lysis (Ham’s) test.
B. Bone marrow flow cytometry.
C. Direct antiglobulin (Coombs’) test.
D. Glucose-6-phosphate dehydrogenase level.
E. Osmotic fragility test.

E. Osmotic fragility test.

  • Osmotic fragility test: Osmotic fragility measures red blood cell (RBC) resistance to hemolysis when exposed to a series of increasingly dilute saline solutions. The sooner hemolysis occurs, the greater the osmotic fragility of the cells. – indicates hereditary spherocytosis or thalassaemia
  • Ham’s test: HAM test is used to evaluate patients with suspected PNH (Paroxysmal Noctural Hemoglobinuria) or suspected congential dyserythropoietic anemia, especially with hemosiderinuria, Pancytopenia, decreased RBC acetyl cholinesterase, decreased leukocyte alkaline phosphatase, negative direct Coomb’s test, and/or apparent marrow failure.
  • BM Flow cytometry: differentiate cells
  • DAT: for antibody mediated haemolysis

S&S of hereditary spherocytosis:
Anaemia, splenomegaly (breakdown of spherocytes in spleen), gallstones (inc bile from RBC breakdown)
Film: spherocytes (small diameter, hyperchromic, less central pallor), >15-20% of cells when haemolytic anaemia present

8

A seven-year-old girl with Morquios syndrome is referred for respiratory assessment prior to a surgical procedure. Her lung function demonstrated the following:


The most likely explanation for this pattern is:
A. decreased chest wall compliance.
B. decreased small airway conductance.
C. increased upper airway resistance.
D. increased chest wall compliance.
E. narrowing of the trachea.
 

 

A. decreased chest wall compliance.

Dec TLC → unable to expand wall, inc RV → obstructive, dec FRC → dec with TLC?

Likely to have dec chest wall compliance from skeletal abns, which is consistent with results

Morquios syndrome 

mucopolysaccharidosis (MPS-IV), short-trunk dwarfism, fine corneal deposits, skeletal dysplasia and preservation of intelligence

PFTs

  • Restrictive disease – decreases total lung capacity (incls residual volume), decreases vital capacity
  • Obstructive disease – produces gas trapping → increases residual volume and FRC esp when considered with respect to TLC

9

A study is comparing the bioavailability of a new oral preparation of a drug (100 mg tablet) with the marketed intravenous preparation (50 mg in 2 mLs). In this crossover study, healthy volunteers were given in random order one 100 mg tablet or 50 mg intravenously (IV). The drug has linear kinetics within the range of concentrations studied. The mean results are as follows:

Which of the following is the best estimate of the oral bioavailability of the tablet?
A. 12.5%.
B. 40%.
C. 50%.
D. 90%.
E. 96%.

D. 90%

Absolute bioavailability compares the bioavailability of the active drug in systemic circulation following non-intravenous administration (i.e., after oral, rectal, transdermal, subcutaneous, or sublingual administration), with the bioavailability of the same drug following intravenous administration.

The absolute bioavailability is the dose-corrected area under curve (AUC) non-intravenous divided by AUC intravenous.

Causes of low bioavailability: Orally administered drugs must pass through the intestinal wall and then through the portal circulation to the liver; both are common sites of 1st-pass metabolism (metabolism of a drug before it reaches systemic circulation). Thus, many drugs may be metabolized before adequate plasma concentrations are reached. Low bioavailability is most common with oral dosage forms of poorly water-soluble, slowly absorbed drugs.

Insufficient time for absorption in the GI tract is a common cause of low bioavailability. If the drug does not dissolve readily or cannot penetrate the epithelial membrane (eg, if it is highly ionized and polar), time at the absorption site may be insufficient. In such cases, bioavailability tends to be highly variable as well as low.

Age, sex, physical activity, genetic phenotype, stress, disorders (eg, achlorhydria, malabsorption syndromes), or previous GI surgery (eg, bariatric surgery) can also affect drug bioavailability.

10

The addition of starch to oral rehydration solution increases water absorption by which mechanism?
A. Aquaporin transport.
B. Colonic fermentation.
C. Enterohepatic reabsorption.
D. Sodium-glucose co-transport.
E. Sodium-Potasium A TPase.

B. Colonic fermentation

11

In the fetus with a structurally normal heart. The percentage of pulmonary arterial blood flow that is directed through the ductus arteriosus is:
A. 10.
B. 30.
C. 50.
D. 70.
E. 90.

E. 90.

12

During acute hypovolaemia, which of the following mediators produces dilation of the renal afferent arteriole?

A. Aldosterone.

B. Angiotensin II.

C. Anti diuretic hormone.

D .  Prostaglandin I2.

E. Thromboxane.
 
 

D .  Prostaglandin I2.

When renal blood flow is reduced (indicating hypotension) or there is a decrease in sodium and chloride ion concentration, the macula densa of the distal tubule releases prostaglandins, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin-angiotensin-aldosterone system, to increase blood pressure and increase retention of sodium ions via aldosterone.

The macula densa cell can also increase the local blood pressure of the afferent arterioles by increasing the synthesis of nitrous oxide or decreasing the synthesis of adenosine or ATP.

If the afferent arterioles are constricted then the blood pressure in the capillaries of the kidneys will drop.

13

A two-year-old boy presents with an incidentally noted abdominal mass. He is found to have sparse pubic hair. Investigation confirms he has a hepatoblastoma.
Virilization is most likely in children with ectopic production of:
A. alpha fetoprotein.
B. androstenedione.
C. human chorionic gonadotrophin
D. luteinizing hormone
E. testosterone.

C. human chorionic gonadotrophin

14

A woman presents for genetic counselling early in her first pregnancy. Her husband has a disorder caused by a mitochondrial DNA point mutation; several other members of his family are also affected.
The risk that this baby will be affected by the same condition is closest to:
A. 0%.
B. 5%.
C. 25%.
D. 50%.
E. 100%.

A. 0%.

Mitochondria contain own chromosomes, which are maternally derived. Diseases with mitochondrial mutations have inheritance through maternal line eg mitochondrial myopathies (MELAS and MERRF)

15

A 12-year-old girl presents to the Emergency Department following a motor vehicle accident complaining of neck pain. She was a front seat passenger wearing a seat belt in a stationary car which was hit from behind by a vehicle travelling at approximately 30 kilometers per hour. On examination she has no bony tenderness and full neck movements with no neurological deficit.

Which of the following best describes the lateral cervical spine radiograph shown above?
A. Fracture C2 pedicles.
B. Fracture odontoid peg.
C. Pseudosubluxation of C2 on C3.
D. Spondylolisthesis of C2 on C3.
E. Anterior wedge fracture C3.

C. Pseudosubluxation of C2 on C3.

Pediatric pseudosubluxation refers to normal mobility of C-2 on C-3 in flexion which may be so pronounced as to be mistake for pathologic motion; (is normal in children < 8 years old);

Pseudosubluxation may be seen in 40% of children at C2-C3 level and in 14% of children at the C3-C4 level
etiology:

  • pediatric C-spine (up to 8 yrs of age) has greatly increased physiologic mobility as compared to the adult;
  • occurs because of increased ligamentous laxity, more horizontal nature of facet joint (30 deg vs. 60-70 deg in adult);
  • in children, fulcrum of motion that is relatively greatest at C2-C3 level (compared w/ C5-C6 in the adult);
  • 70% of C-spine frx in infants and children occur from C1 to C3;
  • hence increase frequency of atlantoaxial rotatory subluxation as compared to the adult;
  • in normal circumstances, this anterior displacement only occurs in flexion, and should not occur in extension;

16

Children who are born with extremely low birth weight are surviving at higher rates than ever before. What is the prevalence of severe neurological disability in surviving children who are born with extremely low birth weight?
A. Less than 10%.
B. 10 to 20%.
C. 30 to 40%.
D. 50 to 60%.
E. Over 80%.

B. 10 to 20%

17

The anterior pituitary gland releases all of the following hormones except:
A. adrenocorticotropin.
B. growth Hormone.
C. leuteinising hormone.
D. thyroid stimulating hormone.
E. vasopressin.

E. vasopressin.

18

The key event which directly initiates myocardial fibre contraction is:
A. active uptake of calcium into sarcoplasmic reticulum.
B. rapid entry of sodium through fast ion specific channels.
C. release of stored calcium from sarcoplasmic reticulum.
D. slow inward calcium current.
E. slow inward sodium current.

C. release of stored calcium from sarcoplasmic reticulum.

19

Lymph nodes are the major site for interaction between antigen presenting cells and:
A. B cells.
B. macrophages .
C. neutrophils.
D. NK cells.
E. T cells.

E. T cells.

20

Adolescence represents a stage of development where a number of cognitive and psychosocial tasks must be mastered.
Which one of the following is not a task of adolescence?
A. Concrete operational thinking.
B. Establishing stronger peer group relationships.
C. Forming sexual relationships.
D. Identity formation.
E. Separation from the family group.

A. Concrete operational thinking.

21

Which measure on spirometry is the most sensitive in children with small airways disease?

A. Forced Vital Capacity (FVC).
B. Forced Expiratory Volume in 1 second (FEV1).
C. Forced Expiratory Flow 25%-75% (FEF 25%-75%).
D. Peak flow.
E. FEV1/FVC ratio.

C. Forced Expiratory Flow 25%-75% (FEF 25%-75%).

FEV1 correlates well with severity of obstructive disease

Maximal midexpiratory flow rate (average flow during middle 50% for forced vital capacity) is more reliable indicator of mild airway obstruction with sensitivity to changes in residual volume and vital capacity

  • flow rate at 25% VC is useful index of small airway function

Peak flow reduced in advanced obstructive disease but may not be altered when obstruction is moderate or mild and need cooperation

FEV1/FVC ration ie the proportion of the vital capacity exhaled in the first second – distinguishes between reduced FEV1 due to restricted lung volume and that due to obstruction. Obstruction is defined as an FEV1/FVC ratio of <70%

22

An otherwise well ten-year-old boy has chronic kidney disease secondary to posterior urethral valves. His mother has noted that he is often very thirsty and drinks up to 2500mls of fluids per day.
 


A. 5%.
B. 10%.
C. 20%.
D. 30%.
E. 40%.

A. 5%.

100x (70x0.2)/(140x2) = 5

The fractional excretion of sodium (FENa) is the percentage of the sodium filtered by the kidney which is excreted in the urine. It is measured in terms of plasma and urine sodium, rather than by the interpretation of urinary sodium concentration alone, as urinary sodium concentrations can vary with water reabsorption.

In clinical use, the fractional excretion of sodium can be calculated as part of the evaluation of acute renal failure in order to determine if hypovolemia or decreased effective circulating plasma volume is a contributor to the renal failure. "Measurement of the urine sodium concentration provides information on the integrity of tubular reabsorptive function. Low urine sodium concentration thus indicates not only intact reabsorptive function but also the presence of a stimulus to conserve sodium "

23

A 15-year-old with a history of complex partial seizures is currently on carbamazepine. He develops acute sinusitis and is prescribed an antibiotic by his general practitioner. He presents to the emergency room with depressed conscious state and status epilepticus. He is found to have markedly elevated carbamazepine levels.
Which of the following antibiotics is he likely to have been prescribed?
A. Amoxicillin-clavulinic acid.
B. Cefaclor.
C. Ciprofloxacin.
D. Doxycycline.
E. Erythromycin

E. Erythromycin.

Carbamazepine is a CYP 3A4 substrate as well as an inducer of multiple cytochrome P450 isoenzymes and may be subject to a number of drug-drug interactions. Toxic levels of carbamazepine may result from CYP 3A4 inhibition due to erythromycin, fluoxetine, and cimetidine, among other drugs.

CYP 3A4 inducers, such as phenytoin and phenobarbital, may decrease carbamazepine levels. Plasma levels of many medications, including haloperidol and clozapine, are reduced in the setting of carbamazepine use.

24

A previously well 14-year-old boy presents to the emergency department with a history of increasing wheeze and shortness of breath over several days. On examination, he has facial fullness and erythema, and his neck veins are easily visible. His chest X-ray is shown below.

A radiologically guided biopsy yields tissue consistent with lymphoblastic lymphoma. Immunocytochemistry is likely to show the cells originate from which lymphocyte group?

A. Mature B cells.
B. Natural killer (NK) cells.
C. Precursor B cells.
D. Reed-Sternberg cells.
E. T cells.

E. T cells.

T-cell ALL: obstruction from anterior mediastinal mass (thymus or nodes) – mostly seen in adolescent boys with T-cell ALL (T-cell ALL also has higher leukocyte count), 50-75% Reed-Sternberg cells (Hodgkins)

25

Patients with isolated hemihypertrophy are at increased risk of intra-abdominal tumours. Which of the following tumors is the most likely to develop?
A. Adrenal carcinoma.
B. Hepatoblastoma.
C. Neuroblastoma.
D. Phaeochromocytoma.
E. Wilms tumour.

E. Wilm tumour (but answer key says phaeochromocytoma)

Wilms' tumor, a cancer of the kidney, is the most common cancer in children with BWS or isolated hemihypertrophy. Most children with this cancer develop it before age 5, but some children can develop it later. Ninety five percent of Wilms' tumors occur in BWS or hemihypertrophy patients by age 8. Hepatoblastoma, a cancer of the liver, is the second most common cancer in patients with Beckwith-Wiedemann Syndrome or isolated hemihypertrophy. This cancer usually develops by 2 years of age. Rarely, patients with BWS or isolated hemihypertrophy develop other cancers.

26

Which one of the following antibiotics is the most useful for treating community acquired infections caused by resistant Staphylococcus aureus (MRSA)?
A. Amoxicillin-clavulanate acid.
B. Cephalexin.
C. Clindamycin.
D. Erythromycin.
E. Flucloxacillin.

C. Clindamycin.

27

In which segment of the gastrointestinal tract is most of dietary iron absorbed?
A. Distal ileum.
B. Duodenum.
C. Jejunum.
D. Proximal ileum.
E. Stomach.

B. Duodenum.

28

Which of the following medications is least likely to cause significant sedation?
A. Atomoxotine.
B. Clonidine.
C. Fluoxetine.
D. Methylphenidate.
E. Risperidone.

D. Methylphenidate.

29

CDC (Centre for Disease Control) BMI (body mass index) charts have been recommended as a screening tool to identify individuals who are overweight.
Which of the following BMI’s define a child likely to be obese?
A. >25 kg/m2.
B. >30 kg/m2.
C. >85th percentile for age.
D. >85th <95th percentile for age.
E. equal to or >95th percentile for age.

E. equal to or >95th percentile for age.

30

Macrolide antibiotics have been increasingly used in the treatment of children with cystic fibrosis. The beneficial effect is most likely:
A. killing of staphylococcus aureus.
B. killing of atypical mycobacteria.
C. modulation of airway inflammation.
D. reduced adherence of Pseudomonas aeruginosa to airway epithelium.
E. upregulation of CFTR.

C. modulation of airway inflammation.

Macrolides – reduce virulence properties of P. aeruginosa (biofilm production) and contribute anti-inflammatory effects. 

Long term azithromycin shown to improve lung function in pts with chronic P. aeruginosa infection.

31

A 27-year-old pregnant Somali woman is referred from the antenatal clinic after a screening test shows she is a carrier of Haemoglobin S (HbS). Her husband, also Somali, has not been tested.

Given that 1 in 10 Somalis are HbS carriers, the risk of her unborn baby having sickle cell disease is:
A. 1 in 2.
B. 1 in 4.
C. 1 in 10.
D. 1 in 20.
E. 1 in 40.

E. 1 in 40.

Dad has 1/10 risk of being a carrier. If he is a carrier, he has a ½ risk of passing on gene. Therefore mothers risk of passing on gene (1/2) x dad risk (1/2) x chance of being HbS (1/10) = 1/40

32

The arterial blood pressure trace of an unwell one-year-old child is shown below.

The child has a one week history of low grade fever with viral symptoms. At presentation the child is tachycardic and tachypnoeic with poor peripheral perfusion. The most likely diagnosis is:

A. cardiac tamponade.
B. coarctation of aorta.
C. dilated cardiomyopathy.
D. septic shock.
E. viral myocarditis.

A. cardiac tamponade.

Pulsus paradoxus
Normally during inspiration, systolic blood pressure decreases ≤10 mmHg.[1], and pulse rate goes up slightly. This is because the intrathoracic pressure becomes more negative relative to atmospheric pressure. This increases systemic venous return, so more blood flows into the right side of the heart. However, the decrease in intrathoracic pressure also expands the compliant pulmonary vasculature. This increase in pulmonary blood capacity pools the blood in the lungs, and decreases pulmonary venous return, so flow is reduced to the left side of the heart. Also the increased venous return to the right side of the heart expands the right heart and directly compromises filling of the left side of the heart. Reduced left-heart filling leads to a reduced stroke volume which manifests as a decrease in systolic blood pressure. The decrease in systolic blood pressure leads to a faster heart rate due to the baroreceptor reflex, which stimulates sympathetic outflow to the heart.

33

An infant is born at 26 weeks gestational with a birth weight of 750g. What are the expected insensible water losses (mls/kg/hour) on day one of life?
A. 0.5 – 1.0.
B. 2.0 – 3.0.
C. 4.0 – 5.0.
D. 8.0 –10.0.
E. 12.0 – 15.0.

B. 2.0 – 3.0.

Insensible water loss

  • Preterm – 2.5-3mL/kg/hr
  • Term 0.7-1mL/kg/hr

34

Which one of the following drugs will most likely lead to an increase in tacrolimus drug levels and nephrotoxicity?
A. Acyclovir.
B. Amoxycillin.
C. Fluconazole.
D. Prednisone.
E. Rifampicin.

C. Fluconazole.

35

Human Metapneumovirus infection is associated with which of the following?
A. Bronchiolitis.
B. Croup.
C. Febrile convulsions.
D. Gastroenteritis.
E. Viral exanthem.

A. Bronchiolitis.

36

Supplementation with which of the following micronutrients has been shown to be most effective in the treatment of chronic diarrhoea in malnourished children?
A. Cyanocobalamin.
B. Folic acid.
C. Iron.
D. Magnesium.
E. Zinc.

E. Zinc.

Zinc supplements – important factor in prevention and therapy of chronic diarrhoea

Promotes ion absorption, restores epithelial proliferation and stimulates immune response

37

A five-year-old boy presents to the Emergency Department with a one week history of intermittent vomiting and increasing lethargy with polyuria and thirst. Examination reveals deep sighing respiration with severe dehydration. His initial blood chemistry is shown below:

Which of the following substances best accounts for the elevated anion gap?
A. Glucose.
B. Hydrogen.
C. Ketones.
D. Lactate.
E. Phosphate.

C. Ketones.

38

A four-year-old boy has an 11-year-old sister who has recently been diagnosed with Type 1 diabetes mellitus. His parents seek advice about the risk of their son also developing Type 1 diabetes.
His lifetime risk of developing Type 1 diabetes mellitus is closest to:
A. 0.5%.
B. 5%.
C. 25%.
D. 50%.
E. 100%.

B. 5%.

Close relatives (children, siblings) of a person with type 1 diabetes have an increased risk of developing type 1 diabetes, compared to a person with no family history (5 to 6 percent versus 0.4 percent, respectively)

39

The optimal method of rehydration in children with gastroenteritis is widely accepted to be through the use of Oral Rehydration Solution because it optimises the absorption of both water and electrolytes in appropriate quantities.
Which of the following best describes the mechanism by which water is absorbed from the gastrointestinal lumen?
A. Activation of adenylate cyclase.
B. Active transport via sodium - glucose cotransporter.
C. Active transport via sodium - water cotransporter.
D. Passive diffusion across an osmotic gradient.
E. Utilisation of sodium - potassium ATPase pump.

D. Passive diffusion across an osmotic gradient.

40

A term infant was noted to have a grade 3/6 systolic murmur prior to discharge. Oxygen saturations were measured at 90%. The child’s ECG is shown below.

The most likely diagnosis is:

A. atrioventricular septal defect.
B. pulmonary valve stenosis .
C. severe aortic stenosis.
D. tricuspid atresia.
E. truncus arteriosus.

B. pulmonary valve stenosis .

Mixing, R axis deviation, R ventricular hypertrophy

41

A 40-year-old woman has chorionic villus sampling because of the age-related risk of chromosomal abnormalities in her pregnancy. The karyotype is shown below. There is no evidence of confined placental mosaicism.

The most likely outcome for this pregnancy is:

A. a child with Angelman syndrome.
B. a child with multiple congenital malformations who dies in the first weeks of life.
C. a child with Prader-Willi syndrome.
D. a normal child.
E. spontaneous abortion.

E. spontaneous abortion.

Chromosome 15 TRISOMY
Angelman and Prader-Willi both result from loss of gene at chromosome 15q11-13

  • failure to inherit the active gene causes the syndrome
  • failure to inherit the paternal copy → Prader-Willi (paternal deletion or maternal UPD)
  • failure to inherit the maternal copy → Angelman (maternal deletion or paternal UPD)

Imprinting/UPD

  • differential activation of genes depending on which parent they were inherited from
  • imprinting “silences” the gene transcription
  • involves DNA – methylation (blocks transcripts → gene turned off), demethylation = turned on
  • mechanisms – chromosomal deletions, uniparental disomy, imprinting centre mutations
  • known chromosomes – 7, 11, 13, 14, 15, 17, 22
  • occurs during gametogenesis – stably transmitted during somatic mitosis
  • reversible on passage through opposite paternal germline
  • when mutation arises in female ancestor:
    • female imprinting cannot be reversed (ie son can’t reprint for their kids) → transmission through male gives PWS
  • when mutation arises in male ancestor:
    • male imprinting cannot be reversed → female germline → AS

Prader-Willi syndrome – 15q11-13, inherited from mother

  • 1/10000-15000 births
  • hypotonia
  • developmental delay, intellectual disability
  • FTT in infancy
  • Facial dysmorphism
  • Hypogonadism
  • Voracious appetite with obesity in childhood and adulthood
  • Behavioural problems

Angelman syndrome – inherited from father

  • 1/15000-20000 births
  • severe mental retardation
  • microcephaly
  • ataxic gait
  • absence of speech

Testing for AS/PWS

  • methylation studies – primary investigation
  • FISH for deletions
  • Microsatellite analysis (UPD studies)
  • Mutational analysis - research

42

Which vitamin B complex nutritional deficiency is most likely to cause angular cheilosis and glossitis?

A. Cobalamin.
B. Folate.
C. Niacin.
D. Riboflavin.
E. Thiamin.

D. Riboflavin.

Riboflavin (B2), iron deficiency, zinc deficiency

43

According to the diagram shown above, the most common type of oesophageal atresia is:

A. a.
B. b.
C. c.
D. d.
E. e.

A. a.

44

A 14-year-old girl with Type 1 diabetes mellitus is seen for follow-up of her diabetes. She has had two severe hypoglycaemic episodes in the last three months. Both of these have been associated with the use of alcohol.
Which of the following mechanisms best explains alcohol related hypoglycaemia?
A. Increased insulin absorption.
B. Increased insulin sensitivity.
C. Interaction with other drug use.
D. Reduction counter-regulatory hormone responses.
E. Suppresses hepatic gluconeogenesis.

E. Suppresses hepatic gluconeogenesis.

45

A new screening test is developed for Condition X. It is trialled in a population of 1100 children, of whom 100 have Condition X and the remainder do not. Of the 200 children who screen positive, 50 have Condition X.
What is the specificity of the screening test?

A. 0.15.
B. 0.25.
C. 0.50.
D. 0.85.

E.  0.94.
 

D. 0.85.

Specificity = # true negs/(# true negs and false pos)

46

Which of the following nutrients is predominantly absorbed in the duodenum and upper small intestine?
A. Bile salts.
B. Calcium.
C. Linoleic acid.
D. Vitamin B12.
E. Vitamin E.

B. Calcium.

Bile salts and vit B12 in distal ileum
Calcium - duodenum

47

An infant with cyanotic congenital heart disease has a blood gas performed in room air which shows a PO2 of 40 mmHg and PCO2 of 40 mmHg. The infant has no associated lung disease. The PO2 and PCO2 in 100% O2 would be closest to:
A. 40 mmHg.
B. 50 mmHg.
C. 80 mmHg.
D. 100 mmHg.
E. 320 mmHg.

B. 50 mmHg.

48

Desmopressin (DDAVP) can limit bleeding in type 1 von Willebrand disease by transiently increasing plasma von Willebrand factor (vWF) and factor VIII (FVIII) levels.

The mechanism by which this occurs is:

A. decreased breakdown of Vwf.
B. increased synthesis of FVIII.
C. increased synthesis of vWF.
D. release of FVIII from platelets.
E. release of vWF from endothelial cells.

E. release of vWF from endothelial cells.

Type 1 – DDAVP induces release of vWF from endothelial cells

May have some effect in type 2, but otherwise no effect

49

Which of the following immune responses best describes ABO incompatibility?
A. Antibody dependent cytotoxicity.
B. Delayed type hypersensitivity.
C. Immediate hypersensitivity.
D. Immune complex mediated.
E. T cell mediated cytotoxicity.

A. Antibody dependent cytotoxicity.

Anti- A or B antibodies
Hypersensitivity
I – anaphylaxis (IgE)
II – cytotoxic Ab dependment (IgM/G, complement)
III – immune complex – IgG/complement
IV – cell-mediated immune response → T cells

50

BCG (Bacille Calmette-Guérin) vaccine is most likely to reduce the risk of:
A. cutaneous tuberculosis.
B. latent tuberculous infection.
C. pulmonary tuberculosis.
D. tuberculous adenitis.
E. tuberculous meningitis.

E. tuberculous meningitis.

Variable efficacy of vaccine. BCG seems to have its greatest effect in preventing miliary TB or TB meningitis,for which reason, it is still extensively used even in countries where efficacy against pulmonary tuberculosis is negligible.

51

A four-year-old boy presents with facial oedema and dark urine two weeks after a bout of tonsillitis. He has been anuric for 18 hours. Initial investigations confirm acute renal failure with markedly elevated serum urea and creatinine. His serum potassium is elevated at 6.8 millimoles / litre.
Which of the following reduces total body potassium?
A. Calcium infusion.
B. Glucose and insulin infusion.
C. Nebulised salbutamol.
D. Sodium bicarbonate infusion.
E. Sodium polystyrene sulphonate (Resonium) enema.

E. Sodium polystyrene sulphonate (Resonium) enema.

52

A 24-week gestation male infant weighing 600 grams is managed with nasopharyngeal continuous positive airways pressure. At 36 hours of age he is receiving 60ml/kg/day of 10% dextrose intravenously. In addition an umbilical arterial line is running at 1ml/hr with 0.45% (half-normal) saline. His urine output is 0.5ml/kg/hour. Analysis of an arterial blood sample reveals the following:

The most appropriate management would be:

A. furosemide.
B. glucose and insulin.
C. increased intravenous fluids.
D. resonium.
E. sodium bicarbonate.

C. increased intravenous fluids.

53

Which of the following best describes the mechanism of action of the thiazolidinediones?
A. Increased insulin sensitivity.
B. Increased insulin synthesis.
C. Stimulation of beta cell proliferation.
D. Stimulation of conversion of pro-insulin to C peptide.
E. Stimulation of insulin secretion.

A. Increased insulin sensitivity.

54

A seven-year-old boy with a diagnosis of intractable epilepsy is prescribed an anticonvulsant. Six months later, he presents with a four hour history of colicky abdominal pain and vomiting. Examination reveals him to be distressed and pale. He is not jaundiced. During the examination he suffers a bout of pain. A diagnosis of renal colic is made.
Which of the following anticonvulsants is most likely to be associated with this clinical scenario?
A. Carbamazepine.
B. Lamotrigine.
C. Phenytoin.
D. Sodium valproate.
E. Topiramate.

E. Topiramate.

Topiramate - CNS effects, Glaucoma, hyperammonemia/encephalopathy, hyperthermia, metabolic acidosis, renal calculus, suicidal ideation.

Renal calculus: Topiramate exhibits weak carbonic anhydrase inhibitory properties and may increase the risk of kidney stones about 2-4 times that of the untreated population. Kidney stones have been reported in children and adults (incidence higher in males). The risk of stones may be reduced by increasing fluid intake.

Carbamazepine - Anemia, agranulocytosis, CNS depression, TENS, Stevens Johnson syndrome, hypersensitivity, hyponatremia, suicidal ideation, activate latent psychosis, confusion/agitation.

Lamotrigine - Aseptic meningitis, blood dyscrasias, CNS depression, multiorgan hypersensitivity, severe and potentially life threatening skin rashes (Stevens Johnson, TENS, angiodema).

Phenytoin- Blood dyscrasias, decreased bone mineral density, hypotension and severe cardiac arrhythmias with IV infusion (must be done slowly), TENS, Steven-Johnson Syndrome, hypersensitivity, suicidal ideation, gingival hyperplasia, megaloblastic anemia, hyperglycemia.
 

Sodium Valproate - CNS depression, hepatic failure, fulminant hepatitis, hyperammonemia/encephalopathy, hypothermia, pancreatitis, multi organ hypersensitivity, suicidal ideation, thrombocytopenia, spina bifida in pregnancy.
 


 

55

In infants with glucose-galactose malabsorption, ingestion of foods containing which of the following carbohydrates is likely to cause severe diarrhoea and dehydration?

A. Fructose.
B. Mannose.
C. Mannitol.
D. Sorbitol.
E. Sucrose.

E. Sucrose.

Fructose, glucose and galactose – monosaccharides not broken down and are absorbed directly
Mannose – not well metabolised
Sucrose – made of fructose and glucose
Sorbitol – sugar alcohol, changed aldehyde group

56

A three-year-old girl is diagnosed with adrenocortical carcinoma. Her maternal aunt died from osteosarcoma at 12 years of age, and her maternal grandmother was treated for breast carcinoma in her early forties. A familial tumour predisposition syndrome is suspected.
The most likely mechanism for this is a germline mutation in which of the following genes?
A. APC.
B. NF1.
C. p53.
D. RB1.
E. RET.

C. p53.

APC – adenomatos polyposis coli
NF1 – neurofibromas
P53 – multiple different types
RB1 – retinoblastoma
RET – MEN, thyroid

57

Which of the following is not a common side effect of therapy with cyclosporin?
A. hirsutism.
B. hypertension.
C. hypomagnesaemia.
D. renal impairment.
E. tinnitus.

E. tinnitus.

58

Which of the following is, the most useful test for assessment of disease activity in systemic lupus erythematosus?
A. Anti-nuclear antibody (ANA).
B. Complement factor 3 (C3).
C. C-reactive protein (CRP).
D. Extractable nuclear antigen antibodies (ENA).
E. Haemoglobin .

B. Complement factor 3 (C3).

59

Oral medications, Drugs A and B, have the following properties in healthy individuals.

Compared to healthy individuals, patients with cirrhosis have a much higher concentration of drug A than drug B.

The best explanation for this is the difference in:

A. bioavailability.
B. volume of distribution.
C. renal clearance.
D. hepatic clearance.
E. protein binding.

A. bioavailability.

60

Jaundice in the first 24 hours of life is most commonly due to:
A. biliary atresia.
B. breast milk jaundice.
C. haemolytic disorders.
D. hepatocellular damage secondary to birth asphyxia.
E. physiological jaundice.

C. haemolytic disorders.

61

The most common psychiatric cause of school refusal in older adolescents is:
A. conduct disorder.
B. oppositional defiant disorder.
C. obsessive compulsive disorder.
D. separation anxiety disorder.
E. social phobia.

E. social phobia.

The hallmarks of social anxiety disorder (SAD) are excessive fears of scrutiny, embarrassment, and humiliation, although patients often manifest broader fears of social inadequacy and fears of criticism and negative evaluation by others. In social or performance situations, persons with SAD may also experience physical manifestations of anxiety, include blushing, sweating, trembling, and palpitations, which sometimes can take the form of a full panic attack.

Persons often fear that others will notice that they are irrationally anxious. They also often experience anticipatory anxiety, worrying for hours or days prior to a feared event. Persons with SAD may completely avoid some or most social activities, or they may participate with intense anxiety or with more subtle avoidance behaviors, such as limiting eye contact or the initiation of conversations. Upon leaving a social situation, persons with SAD often focus on their perceived shortcomings, berate themselves, and feel depressed.

Avoidant personality disorder — In patients with severe SAD, symptoms are pervasive and overlap with those of avoidant personality disorder. Common clinical manifestations include a widespread avoidance of essential activities (including school avoidance and work absenteeism), pervasive low self esteem, and a relatively isolated existence with social contact limited to close family and very few, if any, friends. Over 50 percent of persons with the generalized subtype of SAD meet criteria for avoidant personality disorder.

62

The major objective of a phase III clinical trial is to determine which one of the following?
A. Cost effectiveness.
B. Efficacy of an experimental therapy.
C. Efficacy of a standard therapy.
D. Maximum tolerated dose.
E. T oxicity profile.

B. Efficacy of an experimental therapy.

63

If Rubella vaccine is inadvertently given to a woman in the first four weeks of pregnancy the risk of vaccine related birth defects is closest to:
A. 1%.
B. 5%.
C. 10%.
D. 20%.
E. 50%.

A. 1%.

64

Which of the following psychoactive medications is most likely to cause excessive weight gain?
A. Fluoxetine.
B. Haloperidol.
C. Olanzapine.
D. Quetiapine.
E. Sodium valproate.

C. Olanzapine.

65

Which subgroup of children with cerebral palsy is at most risk of hip displacement?
A. Ataxic.
B. Hypotonic.
C. Spastic diplegia.
D. Spastic hemiplegia.
E. Spastic quadriplegia.

E. Spastic quadriplegia.

Children who suffer from cerebral palsy and do not walk before the age of 5 have a 58% incidence of hip dislocation (44% bilateral, 14% unilateral). Other factors involved in the causation of hip dislocation include four limb cerebral palsy and tightness of the adductor and iliopsoas muscles with concomitant weakness in the abductor muscles at the hip. (BMJ. 1999 April 17; 318(7190): 1021–1022)

Spastic diplegia is bilateral spasticity of the legs that is greater than in the arms.

Infants with spastic hemiplegia have decreased spontaneous movements on the affected side and show hand preference at a very early age. The arm is often more involved than the leg and difficulty in hand manipulation is obvious by 1 yr of age.

Spastic quadriplegia is the most severe form of CP because of marked motor impairment of all extremities and the high association with mental retardation and seizures.
(Nelsons)
 

66

A one-day-old male infant of a diabetic mother has a seizure. At the time his blood glucose registers as 'LO' on the bedside glucometer and a formal blood glucose is measured as 1.2 mmol/L [ 2.8 - 7.8 mmol/L].

Which of the following investigation profiles is most likely?
 

B. Raised serum insulin, decreased serum ketones, reducing substances negative.

67

Which of the following cells is most likely to cause bony erosions in patients with rheumatoid arthritis?

A. T-Lymphocyte.
B. B-Lymphocyte.
C. Osteoclast.
D. Osteoblast.
E. Plasma cells.

C. Osteoclast.

68

Pyloric stenosis is a disorder with polygenic inheritance. The male to female ratio is about 4:1. Who of the following is most likely to develop pyloric stenosis?
A. The brother of an affected boy.
B. The daughter of an affected woman.
C. The daughter of an affected man.
D. The son of an affected man.
E. The son of an affected woman.

E. The son of an affected woman.

69

In the performance of spirometry in 6-12 year old children, the flow volume curves should appear similar in configuration on repeat testing.
What is the maximum allowable variation on repeat testing?

A. 5%

B. 10%

C. 15%

D. 20%

E. 25%
 

A. 5%

70

The most likely cause of an IgE level of 2000 (Normal: 0-35kIU/L) in a two-year-old child is:

A. allergic rhinitis.
B. asthma.
C. atopic dermatitis.
D. food allergy.
E. hyperIgE syndrome.

C. atopic dermatitis.