2006 Paper A Flashcards Preview

Paeds Exam > 2006 Paper A > Flashcards

Flashcards in 2006 Paper A Deck (70):
1

There is considerable variation in the age at which teeth erupt. Which of the following are usually the first teeth to erupt?

A. Lower central incisors.

B. Lower first molars.

C. Lower lateral incisors.

D. Upper central incisors.

E. Upper lateral incisors.

A. Lower central incisors. 

2

The epithelial sodium channel located in the collecting duct is regulated by which of the following?

A. Adrenocorticotrophic hormone (ACTH).

B. Aldosterone.

C. Amiloride.

D. Cyclic AMP .

E. Renin.

B. Aldosterone

Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release (secretion) of potassium ions in the collecting ducts and distal convoluted tubule of the kidneys' functional unit, the nephron.
Amiloride works by directly blocking the epithelial sodium channel (ENaC) thereby inhibiting sodium reabsorption in the late distal convoluted tubules, connecting tubules, and collecting ducts in the kidneys.

3

Telomeres are best defined as:

A. cis-acting DNA elements responsible for segregation of chromosomes at mitosis and meiosis.

B. proteins which bind to promotor elements to initiate transcription of a gene.

C. specialised structures which "cap" the ends of chromosomes.

D. the major non-DNA component of chromatin.

E. the sites at which crossovers occur during pachytene.

C. specialised structures which "cap" the ends of chromosomes.

A telomere is a region of repetitive DNA sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. The telomere regions deter the degradation of genes near the ends of chromosomes by allowing for the shortening of chromosome ends, which necessarily occurs during chromosome replication.[1] Over time, due to each cell division, the telomere ends do become shorter. During cell division, enzymes that duplicate DNA cannot continue their duplication all the way to the end of chromosomes. If cells divided without telomeres, they would lose the ends of their chromosomes, and the necessary information they contain. The telomeres are disposable buffers blocking the ends of the chromosomes, are consumed during cell division, and are replenished by an enzyme, telomerase reverse transcriptase.

4

The embryonic gonad is bipotential. Which of the following hormones determine early differentiation towards the male phenotype?

A. Activin.

B. Antimüllerian hormone.

C. Dihydrotestosterone.

D. Human chorionic gonadotropin.

E. Inhibin.

B. Antimüllerian hormone. 

5

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.

6

Which of the following blood group combinations is most frequently associated with isoimmune haemolytic disease of the newborn?

B. Mother A neg, Infant O pos

  • when also incompatible with group A or B, mother partially protected against sensitization by rapid removal of Rh-positive cells from circulation by preexisting anti-A or anti-B (IgM Ab)
    • therefore answers D and E protective
  • if ABO only: usually mother is type O and infant type A or B
  • ABO occurs in 20-25% pregnancies, haemolytic disease develps in only 10% of such offspring and infants generally type A1 (more antigenic than A2)

7

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. Toxicity profile.

B. Efficacy of an experimental therapy. 

8

Renin release from juxtaglomerular cells is stimulated by:

A beta sympathetic blockade.

B cortisol.

C increased plasma chloride.

D increased vagal activity.

E sodium depletion.

E sodium depletion.

The peptide hormone is secreted by the kidney from specialized cells called granular cells of the juxtaglomerular apparatus via 3 responses:

  1. A decrease in arterial blood pressure (that could be related to a decrease in blood volume) as detected by baroreceptors (pressure-sensitive cells). This is the most causal link between blood pressure and renin secretion (the other two methods operate via longer pathways).
  2. A decrease in sodium chloride levels in the ultra-filtrate of the nephron. This flow is measured by the macula densa of the juxtaglomerular apparatus.
  3. Sympathetic nervous system activity, which also controls blood pressure, acting through the beta1 adrenergic receptors.

9

An otherwise normal five-year-old child is brought to see you because of recurrent generalised convulsions. The child had his first febrile convulsion at 12 months of age, and subsequently has had six afebrile seizures. He is on anticonvulsant therapy. There is no family history of febrile convulsions or epilepsy. His mother asks about risk for sudden, unexplained [unexpected] death due to epilepsy (SUDEP). Which of the following is the greatest risk factor for SUDEP?

A. Idiopathicepilepsy.

B. Male sex.

C. Neurological deficit.

D. Symptomatic epilepsy.

E. Young age.

C. Neurological deficit. 

Risk factors for SUDEP include early age of epilepsy onset, frequent generalized tonic-clonic seizures, and intractable epilepsy. Case-control and cohort studies of SUDEP have identified certain clinical and demographic features as potential risk factors, although these are not all consistently found in all studies:

  • Seizure frequency (>1/month)
  • Medication noncompliance, subtherapeutic AED level
  • Age 20 to 45 years
  • Generalized tonic-clonic seizures
  • Polytherapy
  • Duration of epilepsy (>10 years)
  • Alcoholism
  • Male gender
  • Nocturnal seizures

According to Dr Silberstein - Symptomatic Epilepsy

10

Which of the following best describes the mode of action of aminoglycoside antibiotics?
A. Disruption of cytoplasmic membrane function.
B. Inhibition of bacterial DNA gyrase.
C. Inhibition of cell wall synthesis.
D. Inhibition of protein synthesis.
E. Interference with bacterial folic acid metabolism.

D. Inhibition of protein synthesis.

Aminoglycosides have concentration-dependent bactericidal activity. They bind to the 30S ribosome, thereby inhibiting bacterial protein synthesis.

11

Pulse oximetry is widely utilised in clinical practice to measure the oxygen saturation of haemoglobin. In which of the following situations is the measured saturation likely to be falsely elevated?
A. Carbon dioxide retention.
B. Methaemoglobinaemia.
C. Persistent fetal haemoglobin.
D. Profoundanaemia.
E. Sickle cell anaemia.

B. Methaemoglobinaemia.

When hemoglobin loses an electron and becomes oxidized, it is converted to the ferric state (Fe3+) or methemoglobin. Methemoglobin lacks the electron that is needed to form a bond with oxygen and, thus, is incapable of oxygen transport.
Methemoglobin absorbs light at wavelengths that also absorb deoxyhemoglobin and oxyhemoglobin. Thus, methemoglobin interferes with the colorimetric testing that is used to obtain the percentage of oxyhemoglobin to deoxyhemoglobin.
Traditional pulse oximetry is inaccurate and unreliable in patients with high methemoglobin fractions. Traditional pulse oximetry of patients with low-level methemoglobinemia often reveals falsely low values for oxygen saturation, and it often reveals falsely high values in those with high-level methemoglobinemia.

12

Which of the following anticonvulsants is most likely to decrease the half-life of lamotrigine in a clinically significant manner?
A. Carbamazepine.
B. Clonazepam.
C. Gabapentin.
D. Sodium valproate.
E. Vigabatrin.

A. Carbamazepine.

Carbamazepine: Lamotrigine may enhance the adverse/toxic effect of Carbamazepine. Carbamazepine may increase the metabolism of Lamotrigine. Carbamazepine administration can decrease serum lamotrigine concentrations by approximately 40%.5 Such is likely due to carbamazepine induction of CYP isoenzymes responsible for lamotrigine metabolism.

Sodium Valproate: May enhance the adverse/toxic effect of Lamotrigine and may increase the serum concentration of Lamotrigine.

13

Infants and children with a large patent ductus arteriosus will develop significant cardiomegaly. The mechanism of this is:

A. pressure loading of left ventricle.
B. pressure loading of right ventricle.
C. volume loading of left ventricle.
D. volume loading of left and right ventricle.
E. volume loading of right ventricle.

C. volume loading of left ventricle.

PDA allows blood passage from aorta to pulmonary artery, which returns to left heart via lungs.

14

Many challenging behaviours of children are best understood in terms of the developmental phase the child is negotiating. Which of Erikson's developmental stages best explains toddler tantrums?
A. Autonomy.
B. Identity.
C. Industry.
D. Initiative.
E. Trust.

A. Autonomy.

15

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%.

100x (45x50)/(25x100) = 90%

16

A four-month-old girl presents to the emergency department with a two day history of coryza and low grade fever. Her parents are concerned as they have noticed increasingly noisy breathing today and the baby is not feeding as well as usual. On examination the baby is miserable with a clear nasal discharge, intercostal recession, nasal flaring and grunting respirations.
Which of the following best describes the physiological basis for the audible grunt in this patient?
A. Decreasing residual volume.
B. Generation of negative end-expiratory pressure.
C. Generation of positive end-expiratory pressure.
D. Increasing tidal volume.
E. Respiratory muscle fatigue.

C. Generation of positive end-expiratory pressure.

17

Metformin is the drug of choice in the treatment of Type 2 (non-insulin-dependent) diabetes mellitus in childhood and adolescence. Which of the following is its most frequent side-effect?
A. Gastrointestinal disturbance.
B. Hypoglycaemia.
C. Rash.
D. Taste disturbance.
E. Weight gain.

A. Gastrointestinal disturbance.

18

A 20-month-old boy presents with an acute febrile illness. As part of his work-up he has a full blood examination.

Results are as follows: (image below)

Blood film demonstrates hypochromia and microcytosis of the red blood cells, with an immature neutrophilia and some toxic granulations. Some atypical lymphocytes were also seen.

Dietary history is notable for cow milk intake of over 1000mL/day, with little meat, chicken or fish. His parents are Indian. He was born in Australia.

The next day he has some further investigations. His serum ferritin level is 11μg/L [8-160], and his Hb electrophoresis shows a HbA2 of 3.3% [1.8 - 3.5]. 

Which of the following is the most likely explanation for his anaemia?
A. Alpha thalassaemia minor.
B. Beta thalassaemia major.
C. Beta thalassaemia minor.
D. Iron deficiency anaemia.
E. Iron deficiency anaemia and beta thalassaemia minor.

E. Iron deficiency anaemia and beta thalassaemia minor.

  • Microcytic anaemia, inflam changes, low MCH and MCV
  • Iron deficient hx
  • Low ferritin
  • Raised HbA2
    • HbA2 rarely alters – increased level (>3.4%, normal level 2-3.4%) found in most pts with β-thal trait and in megaloblastic anaemias secondary to vit B12 and folic acid deficiency, decreased levels in iron-def anaemia and α-thal
  • Level of serum ferritin (iron-storage protein) provides estimate of body iron stores in absence of inflammatory disease
    • decreased levels accompany iron deficiency
  • Beta-thal – mild microcytic anaemia characterised by elevated levels of HbA2 and/or fetal Hb concentration, serum iron, total transferrin and ferritin normal, no abn Hb seen on electrophoresis

19

An eight-year-old boy presents to the emergency department with a three day history of double vision.
Examination reveals that the two images are most separated when looking to the right. When looking to the right with the left eye covered, the more medial image disappears.
The nerve involved is the:
A. left abducens.
B. left oculomotor.
C. left trochlear.
D. right abducens.
E. right oculomotor.

D. right abducens.

Binocular diplopia is present with both eyes open and absent when either eye is closed. Binocular diplopia reflects conditions in which the visual axes are misaligned. In general, most patients will close the eye with the dysfunctional muscle unless that is the eye with the much better vision.

The orbital muscles are innervated by cranial nerve III except for the superior oblique (cranial nerve IV) and the lateral rectus (cranial nerve VI) muscles. Any condition that results in palsy of the third, fourth, or sixth cranial nerves can cause binocular diplopia.

When the eyes fix on an image, impairment in the movement of one eye results in projection of the image upon the macular area in the normal eye and to one side of the macula in the paretic eye and thus 2 images are perceived. The image seen by the paretic eye (false image) is ALWAYS outermost. For this boy, diplopia is maximal on looking to the right, and the medial (true) image disappears when covering the left eye. This leaves only the false image. Thus, the abnormality is on abduction of the right eye, initiated by the lateral rectus muscle and innervated by the Right abducens (6th) nerve.

A: Left abducens - Lateral rectus. Patients complain of horizontal diplopia. There is esotropia (inward deviation) of the left eye, worse with gaze into the field of the weak lateral rectus muscle (i.e. to the left). Patients assume a compensatory face turn in the direction of the paralysed muscle. Abduction is commonly limited on the side of the lesion. The patient would complain of diplopia on left lateral gaze, and the medial (true) image would disappear on covering the right eye.

B: Left Occulomotor - may cause both horizontal and vertical diplopia. If complete palsy, patients have ptosis and large unreactive pupil, paralysis of adduction, elevation and depression. The eye rests in the position of abduction, depression and intorsion (medial rotation of upper pole). The left eye deviates laterally in the resting position due to unopposed action of the intact left lateral rectus muscle.

C: Left Trochlear - Superior Oblique. Common cause of vertical diplopia, most palsies being traumatic or idiopathic. The eyes appear conjugate in the primary position, but testing eye movements reveals defective depression of the left eye when adducted (i.e. patient looks to right and down, left eye is adducted but does not look down. More often patients complain of diplopia on looking downwards (when descending stairs or reading) and the head may tilt to the side opposite the weak superior oblique (i.e. to the right) to minimise the diplopia.

D: Right abducens - controls lateral rectus muscle of right eye, thus preventing abduction of this eye. When looking toward the field of the weak muscle (i.e. the right), diplopia is greatest. The eyes appear conjugate in the primary position. Diplopia is horizontal (true and fake image side by side) and is present only when looking to the paralysed side and maximal at the extreme of binocular lateral vision.

20

The electrocardiogram (ECG) of a child with a history of frequent recurrent supraventricular tachycardia is shown above. Which of the following drugs should be avoided because of the increased risk of ventricular tachyarrhythmias secondary to enhanced conduction through the bypass tract?
A. Amiodarone.
B. Digoxin.
C. Flecainide.
D. Propranolol.
E. Sotolol.

B. Digoxin.

ECG shows WPW. Digoxin is contraindicated as it can accelerate conduction across the accessory pathway, shortens refractory period of accessory pathway and can lead to VT. Treatment is with beta blockers, propranolol is first line.

21

Which of the following is the most frequent side-effect of selective serotonin reuptake inhibitor (SSRI) anti-depressants in children?
A. Behavioural activation.
B. Insomnia.
C. Nausea.
D. Suicidal ideation.
E. Tremor.

C. Nausea.

Gastrointestinal symptoms, mostly pain, diarrhea, and nausea, may be problematic, but are often manageable by dose reduction or by assuring that the child takes the medication after eating. Sexual side effects, such as decreased libido or anorgasmia, which are often major deterrents to treatment in adults, are rarely problematic with teens. Although the SSRIs result in weight gain or loss only occasionally, it is a good idea to monitor weight during the first few months of treatment.

However, on October 15, 2004, the FDA issued a public health advisory that directed manufacturers of all antidepressant drugs, including the SSRIs, to revise the labeling for their products to include a boxed warning and expanded warning statements that alert health care providers to an increased risk of suicidality (suicidal thinking and behavior) in children and adolescents being treated with these agents.

22

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.

23

Genomic imprinting is best defined as:

A. a process by which there is selective expression of either the paternally or maternally inherited allele of a gene.
B. inheritance of both copies of a chromosome from one parent.
C. massive amplification of a triplet repeat sequence within a gene.
D. skewing of X-inactivation.
E. the combined effect on a chromosomal locus of methylation of DNA and acetylation of associated histones.

A. a process by which there is selective expression of either the paternally or maternally inherited allele of a gene.

24

What is the major determinant of vocabulary size at age three years?

A. Amount of language stimulation.

B. Child's birth weight.

C. Child's sex.

D. Maternal education level.

E. Maternal IQ.

A. Amount of language stimulation.

25

Which of the following is most strongly associated with substance abuse in adolescence?
A. Adolescent anxiety disorder.
B. Conduct disorder in childhood.
C. Infantile separation anxiety disorder.
D. Learning disorder in childhood.
E. Maternal smoking.

B. Conduct disorder in childhood.

26

Which of the following drugs is most likely to increase the serum levels of cyclosporin to toxic levels?
A. Cotrimoxazole.
B. Erythromycin.
C. Flucloxacillin.
D. Ibuprofen.
E. Rifampicin.

B. Erythromycin.

27

A previously well two-year-old boy presents to his general practitioner with tonsillitis and a macular red rash over his body. He is treated with oral Penicillin V. After two days he is admitted with a sudden onset of fever (38.5°C), irritability and painful skin. On examination he is miserable; screams when touched; has erythema of the face, axillae, neck, buttocks and groin; and peeling skin at the tip of his penis. Rubbing the skin leads to wrinkling and erosions of the epidermis. He has crusting around the mouth and nose and mild conjunctivitis. On day two of admission he develops large flaccid bullae on areas of red skin as shown in the photographs below. Investigations on admission include:

  • Haemoglobin 136 g/L [100-140]
  • Platelets 434 x 109/L [150-400]
  • White Cell Count 15.9 x 109/L [6.0-13.0]
  • Neutrophils 10.8 x 109/L [2.0-6.0]
  • Serum creatinine 30 μmol/L [27-62]
  • C-Reactive Protein < 3mg/L [<8]
  • Gram stain of skin: No organisms seen.

A skin biopsy from this patient would be expected to show a cleavage plane in the:
A. granular layer with a perivascular lymphocytic and neutrophilic infiltrate.
B. granular layer with no inflammatory cell infiltrate.
C. subepidermal layer with eosinophilic infiltration of the dermis.
D. subepidermal layer with full-thickness epidermal necrosis.
E. subepidermal layer with intense perivascular and interstitial mononuclear cell infiltrate.

B. granular layer with no inflammatory cell infiltrate.

Staphylococcal Scalded Skin syndrome. This also usually affects younger children. The disease starts with local peri-oral erythema that spreads over the whole body and progresses to widespread, flaccid bullae that rupture causing exfoliation of the skin that resembles an extensive third-degree burn. There are no organisms that can be cultured from the fluid of the bullae, indicating that the bullae are caused by the toxin and not the bacteria themselves.

Before the bullae form, slight pressure on the apparently normal epidermis may separate it at the basal layer. It may be rubbed off when pressed with a sliding motion. This is Nikolsky's sign.

BIOPSY - cleavage at or below stratum granulosum, no inflammatory cells in bullae or dermis

S&S - prodromal fever, tender skin evolve to generalised erythema with flexural accentuation and then flaccid bullae formation; Nikolsky's sign (lateral pressure on unblistered skin in a bullous eruption with resultant shearing off of the epithelium) present, desquamation follows starting in flexural areas; in contrast to toxic epidermal necrolysis, does not affect oral mucosa and may be a helpful clue to diagnosis.

28

Eczema is associated with a Th2 cytokine profile as evidenced by increased production of which one of the following?

A. Interferon alpha (IFN alpha).
B. Interleukin-2.
C. Interleukin-4.
D. Tumour necrosis factor alpha (TNF alpha).
E. Transforming growth factor beta (TGF beta).

C. Interleukin-4.

Atopic eczema – T cells express skin homing receptor cutaneous lymphocyte-associated antigen (CLA) produce increased levels of TH2 cytokines incl IL-4 and IL-13 → induce isotype switching to IgE synthesis.

29

BCG (Bacille Calmette-Guérin) vaccine is most likely to reduce the risk of:

A. cutaneous tuberculosis.
B. latent tuberculous infection.
C. pulmonarytuberculosis.
D. tuberculous adenitis.
E. tuberculous meningitis.

E. tuberculous meningitis.

30

Widened splitting of the pulmonary and aortic components of the second heart sound during expiration is an auscultatory feature of:

A. atrial septal defect.
B. pulmonary hypertension.
C. severe aortic valve stenosis.
D. severe pulmonary valve stenosis.
E. structurally normal heart.

C. severe aortic valve stenosis.

In structurally normal heart, splitting of 2nd heart sound occurs in inspiration. Negative pressure in chest causes increased blood return to right heart, and decreased return to left heart. Takes longer for volume of blood to be ejected from right heart so aortic valve closes earlier than pulmonary valve.

31

The prevalence of Immunoglobulin A deficiency in the normal population is approximately:
A. 1 in 100.
B. 1 in 500.
C. 1 in 1500.
D. 1 in 2500.
E. 1 in 5000.

B. 1 in 500.

32

Parents with three children seek your advice. Their eldest son, now in his early twenties, has been diagnosed with schizophrenia. What is the likelihood that their youngest son will develop this disorder?

A. 2%.
B. 5%.
C. 10%.
D. 20%.
E. 30%.

C. 10%.

The lifetime risk of schizophrenia is estimated to be 0.2 to 0.7 percent, with an annual incidence of 11 per 100,000
Genetic and environmental risk factors — The 50 percent concordance rate for schizophrenia between monozygotic twins highlights both the importance and limits of genetic predisposition in this condition. In a large population study of 2 million nuclear families in Sweden, risk for schizophrenia was increased 10-fold if a parent had schizophrenia (RR 9.9, 95% CI 8.5-11.6), and 9-fold if a sibling was affected . Risk for schizophrenia was also increased, though to a lesser extent (RR 2.4-3.9), in first degree relatives of patients with bipolar disorder, and risk of bipolar disorder was similarly increased in relatives of patients with schizophrenia, indicating some common genetic effect.

33

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.

increased Na etc from dehydration, also causing inc BE/dec pH

34

The 7-valent pneumococcal conjugate vaccine (Prevenar®) is likely to cover what percentage of invasive pneumococcal isolates in urban Australian and New Zealander children?

A. 10%.
B. 25%.
C. 40%.
D. 60%.
E. 85%.

E. 85%.

35

Compared to term infants, premature infants are most likely to be deficient in which of the following components of the immune system?

A. B cell.
B. Complement.
C. Immunoglobulin.
D. Neutrophils.
E. T cells.

C. Immunoglobulin.

B cells and immunoglobulins

  • newborns have inc susceptibility to infections with gram-neg orgs bc IgM antibodies (heat-stable opsonins) do not cross placenta and C3b (another heat-stable opsonin) also lower
  • → impaired phagocytosis by newborn PMNs
  • Maternal IgG Ab adequate for gram-positive bacteria and viruses
  • Relative deficiency of IgG2 subclass → Ab to capsular polysaccharide Ag may be deficient

Preterm → receive less IgG from mother therefore lower activity

36

In sick preterm infants the most important variable affecting insensible fluid losses is:

A. gestation.
B. incubator humidification.
C. phototherapy.
D. radiant heating.
E. tracheal intubation.

A. gestation

Insensible water loss

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

37

Apart from glucose, which other carbohydrate is absorbed by the intestinal sodium-glucose transporter 1 (SGLT-1)?

A. Fructose.
B. Galactose.
C. Lactose.
D. Mannose.
E. Sorbitol.

B. Galactose.

38

Intravenous infusion of which of the following blood components is most likely to be associated with a septic transfusion reaction?

A. Cryoprecipitate.
B. Freshfrozenplasma.
C. Platelet concentrate.
D. Pooledgammaglobulin.
E. Red cell concentrate.

C. Platelet concentrate.

Bacterial contamination/endotoxemia: The incidence of septic reactions may be as high as 1 case per 700 pooled random donor platelet concentrates and 1 case per 4000 single-donor (apheresis) platelet products. The frequency of sepsis associated with bacterially contaminated RBCs is estimated to be 1 in 250,000. 

39

Three children present to the emergency department with similar symptoms of nausea, severe vomiting, dizziness, and abdominal cramping. All of them had been at the same party two hours previously and had eaten the same potato salad. Analysis of the contaminated food is most likely to yield large numbers of which of the following organisms?

A. Bacillus cereus.
B. Clostridium perfringens.
C. Escherichia coli.
D. Salmonella typhimurium.
E. Staphylococcus aureus.

E. Staphylococcus aureus.

Symptoms of food-borne Staph don't come from the bacteria themselves, but rather from the toxins they release into foods that are left out at room temperature. These toxins are resistant to heating, so recooking food that has been sitting out will not prevent you from getting Staph food poisoning.

How Staph Spreads
Staph food poisoning is food-borne. It occurs when a person consumes a food that is contaminated with the bacteria or its toxins. Staph aureus can be found in meat products, poultry and egg products, mayonnaise-based salads, cream-filled pastries, and other dairy products. It can also withstand higher salt levels than most other bacteria, so it can also live in cured foods, such as ham.

Staph food poisoning usually occurs as a result of human contamination either from dirty hands or through coughing or sneezing into foods that are ready to eat. After the food is contaminated, it sits out and the organism multiplies, resulting in high enough levels of toxin to cause symptoms.

Symptoms of Staph Food Poisoning
Explosive vomiting and nausea, and sometimes diarrhea and severe abdominal pain, starting within 30 minutes to 8 hours of eating the contaminated food and lasting about 1 day.

40

The major contribution to increased cardiac output in a healthy child when running is derived from:

A. decreased left ventricular end-diastolic volume.
B. increased heart rate.
C. increased left ventricular afterload.
D. increased left ventricular preload.
E. increased myocardial contractility.

B. increased heart rate.

Infants are limited to increasing heart rate, for children this is the main way to increase cardiac output but can increase stroke volume, systemic venous return and pulse pressure.

41

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 BB12.
E. Vitamin E.

B. Calcium.

Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:

  • Iron is absorbed in the duodenum.
  • Vitamin B12 and bile salts are absorbed in the terminal ileum.
  • Water and lipids are absorbed by passive diffusion throughout the small intestine.
  • Sodium Bicarbonate is absorbed by active transport and glucose and amino acid co-transport.
  • Fructose is absorbed by facilitated diffusion.

42

Which of the following does not shift the oxyhaemoglobin dissociation curve to the left?

A. Decrease in 2,3 diphosphoglycerate in the red cell.
B. Decrease in carbon dioxide tension.
C. Decrease in pH.
D. Decrease in temperature.
E. Presence of carboxyhaemoglobin.

C. Decrease in pH.

The effectiveness of hemoglobin-oxygen binding can be affected by several factors. The factors can be viewed as having the effect of shifting or reshaping the oxyhemoglobin curve ("the standard curve") of a typical, healthy person. The standard curve is shifted to the right by an increase in temperature, 2,3-DPG, or PCO2, or a decrease in pH. The curve is shifted to the left by the opposite of these conditions. A rightward shift, by definition, causes a decrease in the affinity of hemoglobin for oxygen. This makes it harder for the hemoglobin to bind to oxygen (requiring a higher partial pressure to achieve the same oxygen saturation), but it makes it easier for the hemoglobin to release bound oxygen. Conversely, a leftward shift increases the affinity, making the oxygen easier for the hemoglobin to pick up but harder to release.

43

On average, what proportion of genetic material is shared (i.e. is identical by descent) between two first cousins? Assume the cousins are from an outbred population and there is no consanguinity in the family.

A. 1/64.
B. 1/32.
C. 1/16.
D. 1/8.
E. 1/4.

D. 1/8.

½ x ½ x ½

44

A three-year-old boy is brought to the emergency department with alcohol intoxication following a family party at home. Which of the following best describes the primary hepatic metabolic pathway for alcohol?

A. Conjugation with glucuronic acid.
B. Oxidation by alcohol dehydrogenase.
C. Oxidation by peroxisomal catalase.
D. Oxidation by the microsomal ethanol-oxidizing system (MEOS).
E. Reduction using nicotinamide-adenine dinucleotide phosphate (NADPH) as a cofactor.

B. Oxidation by alcohol dehydrogenase.

45

The calculation of Respiratory Compliance (Crs) in infants can be undertaken using the single-breath occlusion method. When using this technique, the most appropriate method of calculating respiratory compliance is:

A. the pressure at the airway opening recorded during occlusion, divided by flow.
B. the pressure at the airway opening recorded during occlusion, divided by total exhaled volume.
C. the time constant divided by the total exhaled volume.
D. the time constant divided by the airway opening pressure recorded during occlusion.
E. the total exhaled volume divided by pressure at the airway opening recorded during occlusion.

E. the total exhaled volume divided by pressure at the airway opening recorded during occlusion.

46

Which of the following is least likely to cross the placenta from mother to foetus?

A. Calcium.
B. Glucose.
C. Insulin.
D. Thyroxine (T4).
E. TSH receptor antibodies.

C. Insulin.

47

A breast-fed six-month-old boy presents with abdominal distension, loose stools up to six times daily and failure to thrive. He appears to be feeding well. His neonatal metabolic screening tests are all unremarkable. His full blood examination and liver function tests are normal. Faecal microscopy findings are shown below:

What is the most likely diagnosis?

A. Chronic liver disease.

B. Cystic fibrosis.

C. Food allergy.

D. Gastroenteritis.

E. Lymphangiectasia.

B. Cystic fibrosis.

48

An 18-month-old boy presents with cough and fever for three days. His X-rays are shown above. Which of the following best describes the area most affected in this child?

A. Anterior segment right upper lobe.
B. Apical segment right upper lobe.
C. Lateral segment right middle lobe.
D. Posterior segment right upper lobe.
E. Superior segment right lower lobe.

D. Posterior segment right upper lobe.

49

A 26-week gestation infant, intubated and ventilated since delivery, is 12 hours old and has received two doses of surfactant. The ventilation settings are as follows: 

Which of the following alterations to the ventilator settings would be the most appropriate to improve oxygenation?
A. Convert to assist control ventilation.
B. Increase inspiratory time to 0.6 seconds.
C. Increase PEEP to 6 cm H2O.
D. Increase PIP to 32 cm H2O.
E. Increase rate to 70 breaths per minute.

C. Increase PEEP to 6 cm H2O.

Issue is oxygenation and ventilation, FiO2 is 100%, high PIP and rate, Ti good, PEEP low
Oxygenation – alter MAP or FiO2

  • MAP = (PIPxTi) + (PEEPx((60/RR)-Ti)/60/RR)
  • Therefore increase PEEP (most important), PIP, Ti, flow or decrease expiratory time

Ventilation

  • minute ventilation = Vt x RR (should be 0.2-0.3L/kg/min)

Therefore increase PEEP

50

Absorption of gastrointestinal calcium is primarily stimulated by which of the following hormones?

A. 1,25-dihydroxyvitamin D.
B. Cortisol.
C. Growth hormone.
D. Parathyroid hormone (PTH).
E. Thyroid hormone.

A. 1,25-dihydroxyvitamin D.

51

The diagram below represents the bony features of the cervical spine found on radiography. Which of the marked lines best delineates the posterior boundary of the spinal canal?

A. A.
B. B.
C. C.
D. D.
E. E.

B. B.

52

In chronic granulomatous disease, the mechanism of abnormal phagocytic cell function is:

A. abnormalities of the mannose-binding lectin (MBL) pathway.
B. cyclical variation in haematopoiesis.
C. deficiency of myeloperoxidase within the phagocyte granules.
D. failure to produce reactive oxygen intermediates.
E. lack of beta 2-integrin adhesion molecules on neutrophils.

D. failure to produce reactive oxygen intermediates.

Chronic granulomatous disease

  • neutrophils and monocytes capable of normal chemotaxis, ingestion and degranulation but unable to kill catalase-positive microorganisms because of defect in generation of microbicidal oxygen metabolites

53

Which one of the following viruses has not been associated with malignancy?

A. Cytomegalovirus (CMV).
B. Epstein-Barr virus (EBV).
C. Human herpes virus-8 (HHV-8).
D. Human immunodeficiency virus (HIV).
E. Human papilloma virus (HPV).

A. Cytomegalovirus (CMV).

54

A 14-year-old obese girl with a long-standing history of migraine has been having increasing frequency and severity of her headaches. She misses approximately one day per week of school because of her headaches. Despite evaluation for triggering factors and the use of abortive therapy, her headaches continue at the same severity.
You are considering the use of prophylactic therapy.

Which of the following prophylactic medications is not usually associated with weight gain?

A. Amitriptyline.
B. Cyproheptadine.
C. Pizotifen.
D. Propranolol.
E. Sodium valproate.

D. Propranolol.

55

Which brain structure has been most consistently found on functional neuroimaging studies to be associated with the executive function deficits seen in attention deficit hyperactivity disorder?

A. Cerebellum.
B. Limbic system.
C. Pre-frontal cortex.
D. Reticular activating system.
E. Thalamus.

C. Pre-frontal cortex.

Executive function – from prefrontal cortex  organisation, planning, prioritisation, working memory, sequencing response inhibition, cognitive flexibility

  • has connections to anterior lingulate gyrus (for emotions) – not modulated well
  • dysfunction in many neurodevelopmental disorders eg ADHD, ASD, OCD, Tourette;s eating disorder, borderline personality, schizophrenia
  • may be a non-specific feature common to many of psychopathologies
  • neural cell adhesion moecules (NCAMs) mediate connections between cells
  • noradrenaline receptors outnumber the dopa receptors but stimulant mediations still work

Non-executive

  • delay aversion/rewards – ventral fronto-striatal
  • motivation – fronto-limbic
  • temporal processing – parietal/basal ganglia
  • perception – parietal
  • movement – cerebellar

56

In developed countries, breast feeding of term infants is contra-indicated by which of the following maternal infections?

A. Cytomegalovirus.
B. Hepatitis A.
C. Hepatitis B.
D. Hepatitis C.
E. Human immunodeficiency virus (HIV).

E. Human immunodeficiency virus (HIV).

  • contraindications: maternal drugs eg cytotoxics, maternal HIV
  • can transmit maternal drugs (caffeine, alcohol, nicotine), CMV,
  • NB Hep B not contraindication for breastfeeding if HBIg and vaccine given, hep C – transmission possible but not contraindication

57

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 – number who are true neg/(no true negs + no false pos) = 850/1000

58

Which biochemical abnormality is most consistently found in infants subjected to severe environmental deprivation?

A. Decreasedcortisol.
B. Hyperglycaemia.
C. Hypoglycaemia.
D. Hypothyroidism.
E. Increased cortisol.

E. Increased cortisol.

59

A six-year-old boy presents with a six-month history of swallowing problems and speech change. His mother says that his speech is less clear and that fluids occasionally come out of his nose when he is drinking. A photograph of his mouth is shown below. What is the most likely diagnosis?

A. Anterior horn cell disorder.

B. Arnold-Chiari malformation.

C. Cervical cord tumour.

D. Myasthenia gravis.

E. Myotonic dystrophy.

A. Anterior horn cell disorder. 

From Starship.....
-This boy has fasciculations of the tongue.
-Combined with a history of deteriorating speech and fluids coming out of the nose, this suggests an anterior horn cell disorder.
-Anterior horn cell disease is classified as a form of spinal muscular atrophy.
-Because anterior horn cell disease affects the nerve cells responsible for body movements, precursors to the disease include severe reduced muscle tone, diminished limb movements, lack of muscle reflexes, body tremors, difficulty eating and drinking, breathing problems, or inability to stand.
-The mildest form of SMA is type 3 or Kugelberg-Welander disease, where patients can appear normal in infancy.


60

Deficiency of which complement component is most associated with severe pyogenic infections?

A. C1 esterase inhibitor.
B. C3.
C. C4.
D. C8.
E. Properdin.

B. C3.

61

A three-year-old boy undergoing induction for acute lymphoblastic leukaemia is at risk of tumour lysis syndrome due to a high white cell count. Twelve hours following initial chemotherapy, the following investigations were obtained: Which one of the following metabolites is most likely to precipitate within the renal tubules in the patient?

Which one of the following metabolites is most likely to precipitate within the renal tubules in the patient?
A. Allantoin.
B. Calcium phosphate.
C. Hypoxanthine.
D. Sodium nitrate.
E. Uric acid.

B. Calcium phosphate.

  • ARF: Renal tubule precipitation of uric acid, calcium phosphate, or hypoxanthine
  • Rasburicase is recombinant enzyme urate oxidase that oxidizes uric acid to allantoin (able to excrete in urine)
  • Hypoxanthine – product of xanthine oxidase on xanthine
  • Sodium nitrate – used in fertilizers!
  • The phosphorus content of the lymphoblasts is 3-4 times the content of normal lymphocytes → when cells lyse serum phosphorous rises → can cause nephrocalcinosis from calcium phosphate crystal precipitation. This occurs in the renal tubules and microvasculature as the in vivo calcium-phosphorus solubility product exceeds 60-70 because of hyperphosphatemia and may be worsened with iatrogenic alkalinization. Symptomatic hypocalcemia may result from hyperphosphatemia.

62

What is the most common side effect of mycophenolate mofetil?

A. Gastrointestinal disturbance.

B. Impaired renal function.

C. Invasive cytomegalovirus infections.

D. Leucopenia.

E. Post-transplant lymphoproliferative disease.

A. Gastrointestinal disturbance. 

63

Chronic lung disease of prematurity can affect later lung growth. In school-aged children, which part of the lung is most affected?

A. Alveoli.
B. Bronchioles and acini.
C. Interstitial tissue.
D. Main bronchi.
E. Trachea.

B. Bronchioles and acini.

64

Which of the following anthropometric measures in the school-aged child is most specifically associated with level of long-term cardiovascular risk?
A. Body mass index.
B. Height/weight ratio.
C. Skin fold thickness.
D. Waist circumference.
E. Weight.

D. Waist circumference.

65

The parents of a child in the Intensive Care unit with a terminal illness make a choice not to pursue further treatment for their child's condition. Medical advice has been that there is little hope that any intervention would prolong the child's life. In this situation, which of the following should not be withheld?

A. Adequate sedation and analgesia.
B. Antibiotics.
C. Artificial hydration and nutrition.
D. Ionotrophic medications.
E. Red Cell transfusion.

A. Adequate sedation and analgesia.

66

The following table shows the results of the primary endpoint of a study of a new treatment for asthma, “Micoffstop”. Patients were recruited in a tertiary referral hospital after Intensive Care Unit admission.

If the same treatment and endpoint was used in a trial in a group of patients with non-ICU hospital admission for asthma, which of these measures of treatment effect is most likely to remain approximately the same?

A. Absolute risk reduction.
B. Cost-benefit analysis.
C. Number needed to treat.
D. Relative risk reduction.
E. Risk-benefit analysis.

D. Relative risk reduction.

67

Which biochemical abnormality is typical for the 'refeeding syndrome' which occurs due to the reintroduction of food after a period of prolonged undernutrition?

A. Hypercalcaemia.
B. Hyperphosphataemia.
C. Hypocalcaemia.
D. Hypophosphataemia.
E. Hypotriglyceridaemia.

D. Hypophosphataemia.

Starting to eat again after a period of prolonged starvation seemed to precipitate cardiac failure. The pathophysiology of refeeding syndrome has now been established. In starvation the secretion of insulin is decreased in response to a reduced intake of carbohydrates. Instead fat and protein stores are catabolised to produce energy. This results in an intracellular loss of electrolytes, in particular phosphate. Malnourished patients' intracellular phosphate stores can be depleted despite normal serum phosphate concentrations. When they start to feed a sudden shift from fat to carbohydrate metabolism occurs and secretion of insulin increases. This stimulates cellular uptake of phosphate, which can lead to profound hypophosphataemia. This phenomenon usually occurs within four days of starting to feed again.

Phosphate is necessary for the generation of adenosine triphosphate from adenosine diphosphate and adenosine monophosphate and other crucial phosphorylation reactions. Serum phosphate concentrations of less than 0.50 mmol/l (normal range 0.85-1.40 mmol/l) can produce the clinical features of refeeding syndrome, which include rhabdomyolysis, leucocyte dysfunction, respiratory failure, cardiac failure, hypotension, arrhythmias, seizures, coma, and sudden death. Importantly, the early clinical features of refeeding syndrome are non-specific and may go unrecognised.

68

You admit an eight-year-old girl to the Intensive Care Unit with septic shock. A randomised controlled trial recently showed that a new drug reduces mortality. In the study, 33 of 110 control patients (30%) died, compared to 30 of 120 (25%) in the treatment group. It costs $2,000 per treatment course. In order to save one life using this new drug, about how much would your hospital have to spend?

A. $2,500
B. $40,000
C. $50,000
D. $60,000
E. $66,000

B. $40,000

EER = 25%, CER = 30%, ARR = 5%
NNT = 100/5 = 20 therefore 20x$2000

69

An eight-year-old girl is brought to the emergency department with a facial rash of one day's duration, as pictured below. She has been febrile and systemically unwell with nausea, but no vomiting. Her white blood cell count is 29.4 x 109/L [5.50 - 11.0] with a neutrophil count of 26.46 x 109/L [1.8 - 7.0].

Which of the following is the most likely causative agent?

A. Haemophilus influenzae.
B. Pseduomonas aerogiroisa.
C. Staphylococcus aureus.
D. Staphylococcus pneumoniae.
E. Streptococcus pyogenes.

E. Streptococcus pyogenes.

70

The mucopolysaccharidoses are a group of disorders caused by:

A. abnormal accumulation of substrate in lysosomes.
B. abnormal processing of polysaccharide side chains of glycoproteins.
C. dysfunction of membrane ion channels.
D. dysfunction of the mitochondrial respiratory chain.
E. failure of assembly of peroxisomes.

A. abnormal accumulation of substrate in lysosomes.