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Question 1
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A study is developed to compare the calcemia of men and women with Crohn's disease. The objective of the study is to detect any differences between the average calcium levels in men compared to women. Previous studies have shown a normal distribution regarding calcium levels. Which of the the following tests would you most likely apply?
Your Answer: Student's unpaired t-test
Explanation:A t test is a type of statistical test that is used to compare the means of two groups. It is one of the most widely used statistical hypothesis tests in pain studies. There are two types of statistical inferences: parametric and nonparametric methods. Parametric methods refer to a statistical technique in which one defines the probability distribution of probability variables and makes inferences about the parameters of the distribution. In cases in which the probability distribution cannot be defined, nonparametric methods are employed. T tests are a type of parametric method; they can be used when the samples satisfy the conditions of normality, equal variance, and independence. In this case the data is parametric, comparing two independent samples from the same population.
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This question is part of the following fields:
- Clinical Sciences
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Question 2
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170 patients are enrolled in a study to assess the addition of a new antiplatelet drug to aspirin for those who've had a stroke. Out of 170 patients, 120 received the aspirin in addition to the new drug with the remaining 50 patients receiving just aspirin. After 5 years, 18 out of the 120 patients receiving the new drug in addition to aspirin and 10 out of the 50 patients receiving just aspirin, had had a stroke. What is the number needed to treat?
Your Answer: 20
Explanation:The number needed to treat (NNT) is valuable information in treatment decisions. NNT is the inverse of the absolute risk reduction (1/ARR) between two treatment options. Control event rate = 10 / 50 = 0.2
Experimental event rate = 18 / 120 = 0.15Absolute risk reduction = 0.2 – 0.15 = 0.05
Number needed to treat = 1 / 0.05 = 20 -
This question is part of the following fields:
- Clinical Sciences
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Question 3
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A 45-year-old woman with a history of hypothyroidism, presents with ptosis and muscle weakness. She's noticed that her muscle weakness becomes worse towards the end of the day. Clinical examination reveals fatigable ptosis and proximal limb weakness. Myasthenia gravis is suspected. Which receptor is implicated in the pathophysiology of this condition?
Your Answer: Nicotinic acetylcholine receptors
Explanation:Myasthenia gravis (MG) is an organ-specific autoimmune disease caused by an antibody-mediated assault on the muscle nicotinic acetylcholine receptor (AChR) at the neuromuscular junction. Binding of antibodies to the AChR leads to loss of functional AChRs and impairs the neuromuscular signal transmission, resulting in muscular weakness.
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This question is part of the following fields:
- Clinical Sciences
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Question 4
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Choose the karyotype associated with short stature:
Your Answer: 45,XO
Explanation:Turner syndrome (TS) is one of the most common genetic disorders; occurs with an incidence of I: 2,500 female live births. It results from complete or partial chromosome X monosomy. TS is associated with abnormalities of the X chromosome and characteristic clinical features of short stature, gonadal dysgenesis, sexual developmental deficiencies, cardiac and/or renal defects, webbed neck, low-set ears, skeletal deformities including cubitus valgus, a propensity to ear infections and hearing deficits.
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This question is part of the following fields:
- Clinical Sciences
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Question 5
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A case-control study is developed to assess passive smoking as a risk factor for the development of asthma in children. The total number of patients recruited for this study is 200. 40 out of the 200 patients report at least one parent smoking in the house when they were younger. 200 more people without asthma are recruited and 20 out of them report that at least one parent smoked in the house when they were younger. What is the odds ratio of patients with asthma having been exposed to passive smoking during their childhood?
Your Answer: 2.25
Explanation:An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Where
a = Number of exposed cases
b = Number of exposed non-cases
c = Number of unexposed cases
d = Number of unexposed non-cases
OR=(a/c) / (b/d) = ad/bc
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This question is part of the following fields:
- Clinical Sciences
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Question 6
Correct
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Which one of the following statements regarding epidemiological measures is correct?
Your Answer: Cross-sectional surveys can be used to estimate the prevalence of a condition in the population
Explanation:The incidence rate is the number of new cases per population at risk in a given time period. For example, if a population initially contains 1,000 non-diseased persons and 28 develop a condition over two years of observation, the incidence proportion is 28 cases per 1,000 persons per two years, i.e. 2.8% per two years.
Prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seat-belt use). It is derived by comparing the number of people found to have the condition with the total number of people studied, and is usually expressed as a fraction, as a percentage, or as the number of cases per 10,000 or 100,000 people.
Incidence should not be confused with prevalence, which is the proportion of cases in the population at a given time rather than rate of occurrence of new cases. Thus, incidence conveys information about the risk of contracting the disease, whereas prevalence indicates how widespread the disease is. -
This question is part of the following fields:
- Clinical Sciences
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Question 7
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A 19-year-old woman is admitted with diabetic ketoacidosis (DKA). It is her fourth episode in the past two months and she's known to be a type 1 diabetes mellitus patient. The doctors suspects she's non-compliant with her treatment to keep her weight down. She often self-discharges after 24 hours. What is the single most appropriate management?
Your Answer: Have a chat after the ward round about why she thinks her control is so bad
Explanation:In many Western countries and health plans in the United States, patients have a primary care physician who acts as a formal gatekeeper for medical specialist care and thereby determines together with the patient whether or not a patient requires medical specialist care. Ideally in such systems, patients are treated in primary care if possible, and referred to medical specialist care if necessary. For the gatekeeper system to be effective, it is vital that adequate decisions are made about when and who to refer. But it is also important that referred patients comply with the referral by consulting a medical specialist. In this case, the GP should discuss with the patient the reasons why she cannot follow the treatment plan. In other words, the GP should detect why the patient is being non-compliant.
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This question is part of the following fields:
- Clinical Sciences
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Question 8
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A 2-day-old girl is admitted by her mother because she gets cyanotic upon feeding and she wouldn't stop crying. The doctors suspect a congenital heart disease. What is the most probable aetiology?
Your Answer: Transposition of the great arteries
Explanation:Transposition of the great arteries results in a significant hypoxemic status that is observed clinically by central cyanosis. The bluish discoloration of the skin and mucous membranes is therefore the basic pattern of clinical presentation in transposition. Its onset and severity depend on anatomical and functional variants that influence the degree of mixing between the two circulations. Limited intercirculatory mixing, usually present if the ventricular septum is intact or the atrial septal defect is restrictive, is related to progressive and profound central cyanosis evident within the first hours of life. Tachypnoea, tachycardia, diaphoresis, poor weight gain, a gallop rhythm, and eventually hepatomegaly can be then detected later on during infancy. Heart murmurs associated with left outflow tract obstruction, due to a persistent arterial duct or a septal defect may be heard, but they are not a constant finding.
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This question is part of the following fields:
- Clinical Sciences
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Question 9
Correct
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Cholecystokinin is secreted from:
Your Answer: I cells in upper small intestine
Explanation:Cholecystokinin (CCK) was discovered in 1928 in jejunal extracts as a gallbladder contraction factor. It was later shown to be member of a peptide family, which are all ligands for the CCK1 and CCK2 receptors. CCK peptides are known to be synthetized in the small intestinal endocrine I-cells and cerebral neurons.
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This question is part of the following fields:
- Clinical Sciences
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Question 10
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Choose the correct statement regarding the standard error of the mean:
Your Answer: Gets smaller as the sample size increases
Explanation:When statistically comparing data sets, researchers estimate the population of each sample and examine them to see whether they are identical. The standard error of the mean (SEM) – not the standard deviation (SD), which represents the variation in the sample – is used to estimate the population mean. Via this process, researchers conclude that the sample used in their studies appropriately represents the population within the error range specified by the pre-set significance level.
The SEM is smaller than the SD, as the SEM is estimated usually with the SD divided by the square root of the sample size. For this reason, researchers are tempted to use the SEM when describing their samples. It is acceptable to use either the SEM or SD to compare two different groups if the sample sizes of the two groups are equal; however, the sample size must be stated in order to deliver accurate information. For example, when a population has a large amount of variation, the SD of an extracted sample from this population must be large. However, the SEM will be small if the sample size is deliberately increased. -
This question is part of the following fields:
- Clinical Sciences
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Question 11
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A study is performed to assess a new proton pump inhibitor (PPI) in 120 elderly patients who are receiving aspirin. A control group of 240 elderly patients is given the standard PPI. The final evaluation after five years revealed that 24 individuals receiving the new PPI experienced an upper GI bleed. What is the absolute risk reduction if 60 individuals receiving the standard PPI experienced the same condition?
Your Answer: 5%
Explanation:Absolute risk reduction (ARR) – also called risk difference (RD) – is the most useful way of presenting research results to help your decision-making. Absolute risk reduction = (Control event rate) – (Experimental event rate) = 0.05 = 5% reduction
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This question is part of the following fields:
- Clinical Sciences
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Question 12
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A 69-year-old woman is admitted with confusion. She's known to have a history of multiple myeloma. Blood exam reveals the following: Na+ = 147 mmol/l, K+ = 4.7 mmol/l, Urea = 14.2 mmol/l, Creatinine = 102 μmol/l, Adjusted calcium = 3.9 mmol/l. What is the single most appropriate management?
Your Answer: IV 0.9% saline
Explanation:NICE guidelines on hypercalcemia recommend that maintaining good hydration equals drinking 3-4 L of fluid/day, provided there are no contraindications. A low calcium diet is not necessary because intestinal absorption of calcium is reduced. The patient should avoid any other drugs or vitamins that could worsen the hypercalcemia. Mobilization is encouraged and any symptoms of hypercalcemia should be reported.
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This question is part of the following fields:
- Clinical Sciences
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Question 13
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A non-cyanosed 1-year-old female patient has a continuous murmur which is loudest at the left sternal edge. What pulse abnormality is most associated with patent ductus arteriosus if that's her suspected diagnosis?
Your Answer: Collapsing pulse
Explanation:DIAGNOSIS:
A consensus definition for hemodynamically significant PDA is lacking. The diagnosis is often suspected clinically, when an infant demonstrates signs of excessive shunting from the arterial to pulmonary circulation. Continuous or a systolic murmur; note, a “silent” PDA may also occur when the ductus shunt is large enough that nonturbulent flow fails to generate a detectible murmur.
A low diastolic blood pressure (due to runoff into the ductus during diastole, more frequent in the most premature infants).
A wide pulse pressure (due to ductus runoff or steal)Hypotension (especially in the most premature infants)
Bounding pulses
Increased serum creatinine concentration or oliguria
Hepatomegaly -
This question is part of the following fields:
- Clinical Sciences
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Question 14
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Sensorineural deafness is strongly associated with which one of the following?
Your Answer: Rubella
Explanation:Primary rubella infection during pregnancy, particularly during the first trimester, can affect several organs and cause birth defects that are responsible for congenital rubella syndrome (CRS). The most common defects of CRS are hearing impairment (unilateral or bilateral sensorineural), eye defects (e.g., cataracts, congenital glaucoma, or pigmentary retinopathy), and cardiac defects (e.g., patent ductus arteriosus or peripheral pulmonic stenosis). Congenital hearing loss is the most common sequela, occurring in approximately 60% of cases, especially when infection occurs in the 4th month of pregnancy.
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This question is part of the following fields:
- Clinical Sciences
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Question 15
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A 23-year-old woman presents to the A&E with a 24-hour-history of gradual-onset fever, light sensitivity and headache. Clinical examination reveals neck stiffness and an area of rash which does not disappear upon pressure on her right shin. Anamnesis reveals a history of 3 episodes of meningococcal meningitis in the past and she was started on ceftriaxone for another suspected meningitis. However, you suspect that the patients might be immunodeficient. Which immunodeficiency does she most probably have?
Your Answer: C5-9 deficiency
Explanation:Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Disease outcome has been related to the severity of the proinflammatory response in the subarachnoid space. The complement system, which mediates key inflammatory processes, has been implicated as a modulator of pneumococcal meningitis disease severity in animal studies. C5 fragment levels in cerebrospinal fluid (CSF) of patients with bacterial meningitis correlated with several clinical indicators of poor prognosis. The common terminal pathway consists of complement components C5–C9, and activation forms the anaphylatoxin C5a, a strong proinflammatory mediator, and the membrane attack complex (MAC), which creates pores in the bacterial cell wall (12). Deficiencies in these late complement components have been recognized as a cause of recurrent and familial meningococcal infections.
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This question is part of the following fields:
- Clinical Sciences
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Question 16
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How is the left ventricular ejection fraction calculated?
Your Answer: Stroke volume / end diastolic LV volume
Explanation:Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%
Stroke volume = end diastolic LV volume – end systolic LV volume
Pulse pressure = Systolic Pressure – Diastolic Pressure
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This question is part of the following fields:
- Clinical Sciences
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Question 17
Correct
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Choose the correct statement regarding leptin:
Your Answer: Is produced mainly by the hypothalamus
Explanation:Leptin, a 167–amino acid hormone, was discovered in 1994 and is secreted mainly by adipocytes. Plasma leptin levels are significantly correlated with body mass index (BMI) and the total amount of body fat.
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This question is part of the following fields:
- Clinical Sciences
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Question 18
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A 55-year-old woman with established metastatic breast cancer is admitted to the A&E with hypercalcemia. She has a clear medical history, doesn't smoke and works in an office based job. At the A&E she's given intravenous fluids and bisphosphonates. She's finally discharged after normalization of her calcium levels. However, before leaving the hospital she's sent to the endocrinology department for consultation regarding outpatient care and serum calcium monitoring. What is the most appropriate and useful advice for this patient?
Your Answer: Increase fluid intake
Explanation:NICE guidelines on hypercalcemia recommend that maintaining good hydration equals drinking 3-4 L of fluid/day, provided there are no contraindications. A low calcium diet is not necessary because intestinal absorption of calcium is reduced. The patient should avoid any other drugs or vitamins that could worsen the hypercalcemia. Mobilization is encouraged and any symptoms of hypercalcemia should be reported.
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This question is part of the following fields:
- Clinical Sciences
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Question 19
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A 33-year-old woman has missed her last two periods and has been lactating. Upon anamnesis, she claims she's lost weight and she's been suffering from vaginal dryness. The endocrinologist suggests that she checks her prolactin levels. Which of the following inhibits prolactin release from the hypophysis?
Your Answer: Dopamine
Explanation:Dopamine (DA) holds a predominant role in the regulation of prolactin (PRL) secretion. Through a direct effect on anterior pituitary lactotrophs, DA inhibits the basally high-secretory tone of the cell. It accomplishes this by binding to D2 receptors expressed on the cell membrane of the lactotroph, activation of which results in a reduction of PRL exocytosis and gene expression by a variety of intracellular signalling mechanisms.
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This question is part of the following fields:
- Clinical Sciences
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Question 20
Correct
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Which of the following suggests a diagnosis of molluscum contagiosum rather than chickenpox?
Your Answer: Absence of erythema surrounding lesions
Explanation:Molluscum contagiosum (MC), is a viral infection of the skin that results in small, raised, pink lesions with a dimple in the center with little to no surrounding erythema. They may occasionally be itchy or sore. They may occur singularly or in groups. Any area of the skin may be affected, with abdomen, legs, arms, neck, genital area, and face being most common. Onset of the lesions is around 7 weeks after infection. It usually goes away within a year without scarring.
Chickenpox lesions in the early stages may be mistaken for molluscum. However, the presence of associated macules and later vesicles and pustules help to differentiate them. -
This question is part of the following fields:
- Clinical Sciences
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Question 21
Correct
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A 19-year-old female is admitted with a headache, photophobia, fever and confusion. She is managed with antibiotics. What is the mechanism of action of the most commonly used first line antibiotic class?
Your Answer: Inhibition of cell wall synthesis
Explanation:In adults, the most common symptom of meningitis is a severe headache, occurring in almost 90% of cases of bacterial meningitis, followed by nuchal rigidity (the inability to flex the neck forward passively due to increased neck muscle tone and stiffness). Other signs commonly associated with meningitis include photophobia (intolerance to bright light) and phonophobia (intolerance to loud noises).
In the United Kingdom empirical treatment consists of a third-generation cefalosporin such as cefotaxime or ceftriaxone. In the USA, where resistance to cefalosporins is increasingly found in streptococci, addition of vancomycin to the initial treatment is recommended. Penicillins, cephalosporins, carbapenems and monobactams all act via inhibition of cell wall synthesis. -
This question is part of the following fields:
- Clinical Sciences
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Question 22
Correct
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Where is secretin secreted from?
Your Answer: S cells in upper small intestine
Explanation:Secretin is a peptide hormone produced in the S cells of the duodenum, which are located in the intestinal glands. In humans, the secretin peptide is encoded by the SCT gene.
Secretin helps regulate the pH of the duodenum by
1) inhibiting the secretion of gastric acid from the parietal cells of the stomach and
(2) stimulating the production of bicarbonate from the ductal cells of the pancreas.
G cells in the antrum of the stomach release gastrin
I cells in upper small intestine release CCK
D cells in the pancreas & stomach secrete somatostatin
K cells secrete gastric inhibitory peptide, an incretin, which also promotes triglyceride storage. -
This question is part of the following fields:
- Clinical Sciences
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Question 23
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A 29-year-old male patient with a history of three previous chest infections in the past seven months presents with fever, pleuritic pain and productive cough. Chest x-ray shows lobar consolidation and the diagnosis of a fourth chest infection is established, after sputum culture reveals Haemophilus influenzae. The previous chest infections were due to Streptococcus pneumoniae. After a period of six weeks, a full blood count, urea, CRP, electrolytes and chest x-ray turn out as normal. What is the investigation you would choose next?
Your Answer: Serum immunoglobulins
Explanation:Hypogammaglobulinemia occurs due to a variety of underlying primary or secondary immunodeficient states, including HIV which is suspected in this case. The most commonly recognised clinical feature is recurrent infection.
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This question is part of the following fields:
- Clinical Sciences
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Question 24
Correct
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Choose the molecule that acts as the co-receptor for cells expressing antigens linked with MHC class I molecules:
Your Answer: CD8
Explanation:CD8+ T cells recognize antigens in the form of short peptide fragments bound to major histocompatibility complex class I (MHCI) molecules on the target cell surface.1 Specific engagement of peptide-MHCI (pMHCI) complexes via the clonotypically expressed αβ T-cell receptor (TCR) triggers a range of effector functions that play a critical role in protective immunity against intracellular infections and various malignancies.
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This question is part of the following fields:
- Clinical Sciences
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Question 25
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A 42-year-old patient has been admitted with a very swollen and painful right knee. He was unable to walk on it so came into hospital. It is currently being treated as gout with non steroidal anti-inflammatory drugs. You notice he is of short stature, has shortened arms and legs and a flat nasal bridge. A mutation in which gene is responsible for this condition?
Your Answer: Fibroblast growth factor receptor
Explanation:Achondroplasia is a common cause of dwarfism. It is caused by a mutation in fibroblast growth factor receptor 3 (FGFR3). In normal development FGFR3 has a negative regulatory effect on bone growth. In achondroplasia, the mutated form of the receptor is constitutively active and this leads to severely shortened bones. The effect is genetically dominant, with one mutant copy of the FGFR3 gene being sufficient to cause achondroplasia, while two copies of the mutant gene are invariably fatal. A person with achondroplasia thus has a 50% chance of passing dwarfism to each of their offspring. People with achondroplasia can be born to parents that do not have the condition due to spontaneous mutation. It occurs as a sporadic mutation in approximately 80% of cases (associated with advanced paternal age) or it may be inherited as an autosomal dominant genetic disorder.
People with achondroplasia have short stature, with an average adult height of 131 centimeters (52 inches) for males and 123 centimeters (48 inches) for females. -
This question is part of the following fields:
- Clinical Sciences
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Question 26
Correct
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Which one of the following occurs during reverse transcriptase polymerase chain reaction?
Your Answer: RNA is converted to DNA
Explanation:Reverse transcription polymerase chain reaction is a laboratory technique combining reverse transcription of RNA into DNA and amplification of specific DNA targets using polymerase chain reaction. It is primarily used to measure the amount of a specific RNA. The main advantage of PCR is its sensitivity: only one strand of sample DNA is needed to detect a particular DNA sequence. It now has many uses including prenatal diagnosis, detection of mutated oncogenes and diagnosis of infections.
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This question is part of the following fields:
- Clinical Sciences
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Question 27
Correct
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Choose the wrong statement regarding hypocalcaemia:
Your Answer: Chvostek's sign is more sensitive and specific than Trousseau's sign
Explanation:Chvostek and Trousseau signs can be elicited in patients with hypocalcaemia. Chvostek sign is the twitching of the upper lip with tapping on the cheek 2 cm anterior to the earlobe, below the zygomatic process overlying the facial nerve. Trousseau sign (a more reliable sign present in 94% of hypokalaemic individuals and only 1% to 4% of healthy people) is the presence of carpopedal spasm observed following application of an inflated blood pressure cuff over systolic pressure for 3 minutes in hypokalaemic patients.
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This question is part of the following fields:
- Clinical Sciences
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Question 28
Correct
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Choose the correct statement regarding standard polymerase chain reaction:
Your Answer: A thermostable DNA polymerase is required
Explanation:In the PCR, DNA amplification is performed by thermostable enzymes; invariably either family A DNA polymerases from thermophilic and hyperthermophilic Bacteria or family B DNA polymerases from hyperthermophilic Archaea. Family Y DNA polymerase from the hyperthermophilic archaeon Sulfolobus solfataricus, Sso-polY, is also an enzyme marketed for PCR, but with specialist applications. Each thermostable DNA polymerases has different characteristics and to achieve optimal results, the choice of a PCR enzyme depends on the application itself.
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This question is part of the following fields:
- Clinical Sciences
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Question 29
Correct
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You want to compare a new oral hypoglycaemic drug with an existing treatment, which would also lower HbA1c. Which study design would you choose?
Your Answer: Superiority trial
Explanation:When the aim of the randomized controlled trial (RCT) is to show that one treatment is superior to another, a statistical test is employed and the trial (test) is called a superiority trial (test).
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This question is part of the following fields:
- Clinical Sciences
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Question 30
Correct
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Choose the hormone secreted only by the adrenal medulla:
Your Answer: Adrenaline
Explanation:The major endocrine functions of adrenal gland are to produce catecholamines and steroids. Catecholamine, synthesized by the adrenal medulla, is responsible for blood pressure and blood flow regulation whereas steroids produced by the cortex control energy and water homeostasis and immune responses. Glucocorticoids, a major group of adrenal steroids, have a stimulatory effect on catecholamine synthesis in the medulla.
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This question is part of the following fields:
- Clinical Sciences
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