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Question 1
Incorrect
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A 34-year-old male patient is admitted with hemisection of the spinal cord at the level T5, after being stabbed in the back. Which sign would you expect to see by assessing the patient's sensory function and muscle strength?
Your Answer: Contralateral loss of temperature, ipsilateral loss of fine touch and vibration, contralateral spastic paresis
Correct Answer: Contralateral loss of temperature, ipsilateral loss of fine touch and vibration, ipsilateral spastic paresis
Explanation:Depending on the level of SCI, patients experience paraplegia or tetraplegia. Paraplegia is defined as the impairment of sensory or motor function in lower extremities. Patients with incomplete paraplegia generally have a good prognosis in regaining locomotor ability (,76% of patients) within a year. Complete paraplegic patients, however, experience limited recovery of lower limb function if their NLI is above T9. The spinothalamic tract is the one responsible for sensory information such as pain or temperature. However, it decussates at the same level the nerve root enters the spinal cord, meaning that the sensory loss will be contralateral. However, the dorsal column carries sensory fibres for fine touch and vibration and it decussates at the medulla which means that the sensory loss will be ipsilateral. The corticospinal tract is responsible for motor functions and it decussates at the medulla, meaning that the motor function loss will be ipsilateral.
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This question is part of the following fields:
- Clinical Sciences
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Question 2
Correct
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Primarily, funnel plots are used to do what?
Your Answer: Demonstrate the existence of publication bias in meta-analyses
Explanation:Funnel plots are graphical tools to assess and compare clinical performance of a group of care professionals or care institutions on a quality indicator against a benchmark. Incorrect construction of funnel plots may lead to erroneous assessment and incorrect decisions potentially with severe consequences.
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This question is part of the following fields:
- Clinical Sciences
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Question 3
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 4
Incorrect
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A study is carried out to assess the efficacy of a rapid urine screening test developed to detect Chlamydia. The total number of people involved in the study were 200. The study compared the new test to the already existing NAAT techniques. The new test was positive in 20 patients that were Chlamydia positive and in 3 patients that were Chlamydia negative. For 5 patients that were Chlamydia positive and 172 patients that were Chlamydia negative the test turned out to be negative. Choose the correct value regarding the negative predictive value of the new test:
Your Answer: 172/175
Correct Answer: 172/177
Explanation:The definition of negative predictive value is the probability that the individuals with truly negative screening test don’t have Chlamydia. The equation is the following: Negative predictive value = Truly negative/(truly negative + false negative) = 172 / (172 + 5) = 172 / 177
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This question is part of the following fields:
- Clinical Sciences
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Question 5
Incorrect
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What is the site of action of antidiuretic hormone?
Your Answer: Ascending loop of Henle
Correct Answer: Collecting ducts
Explanation:Vasopressin, also called antidiuretic hormone (ADH), regulates the tonicity of body fluids. It is released from the posterior pituitary in response to hypertonicity and promotes water reabsorption in the collecting ducts of the kidneys by the insertion of aquaporin-2 channels.. An incidental consequence of this renal reabsorption of water is concentrated urine and reduced urine volume. In high concentrations may also raise blood pressure by inducing moderate vasoconstriction.
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This question is part of the following fields:
- Clinical Sciences
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Question 6
Incorrect
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Intracellular proteins tagged with mannose-6-phosphate are destined to which of the following organelles?
Your Answer: Rough endoplasmic reticulum
Correct Answer: Lysosome
Explanation:Lysosomal hydrolases are synthesized in the rough endoplasmic reticulum and specifically transported through the Golgi apparatus to the trans-Golgi network, from which transport vesicles bud to deliver them to the endosomal/lysosomal compartment. The explanation of how the lysosomal enzymes are accurately recognized and selected over many other proteins in the trans-Golgi network relies on them being tagged with a unique marker: the mannose-6-phosphate (M6P) group, which is added exclusively to the N-linked oligosaccharides of lysosomal soluble hydrolases, as they pass through the cis-Golgi network. Generation of the M6P recognition marker depends on a reaction involving two different enzymes: UDP-N-acetylglucosamine 1-phosphotransferase and α-N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase.
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This question is part of the following fields:
- Clinical Sciences
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Question 7
Correct
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Which is the formula to calculate the number needed to treat?
Your Answer: 1 / (Absolute risk reduction)
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.
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This question is part of the following fields:
- Clinical Sciences
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Question 8
Incorrect
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Which one of the following statements regarding epidemiological measures is correct?
Your Answer: The prevalence is the number of new cases per population in a given time period
Correct 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 9
Correct
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A 15-year-old girl is admitted to hospital following a ruptured ectopic pregnancy. She comes from a family of Jehovah's Witnesses. Her haemoglobin on admission is 6.7 g/dl. She consents to a blood transfusion but her mother refuses. What is the most appropriate course of action?
Your Answer: Give the blood transfusion
Explanation:People aged 16 or over are entitled to consent to their own treatment. This can only be overruled in exceptional circumstances. Children under the age of 16 can consent to their own treatment if they’re believed to have enough intelligence, competence and understanding to fully appreciate what’s involved in their treatment. This is known as being Gillick competent.
Otherwise, someone with parental responsibility can consent for them.
This could be:
the child’s mother or father
the child’s legally appointed guardian
a person with a residence order concerning the child
a local authority designated to care for the child
a local authority or person with an emergency protection order for the child.
Giving the blood transfusion is therefore both clinically and ethically the right course of action.
Jehovah’s Witnesses frequently carry a signed and witnessed Advance Decision Document listing the blood products and autologous procedures that are, or are not, acceptable to them It is appropriate to have a frank, confidential discussion with the patient about the potential risks of their decision and the possible alternatives to transfusion, but the freely expressed wish of a competent adult must always be respected. -
This question is part of the following fields:
- Clinical Sciences
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Question 10
Incorrect
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A 60-year-old male presents with dyspnoea and an urgent chest X-ray is scheduled. Sputum cultures reveal pneumonia and he receives treatment with erythromycin. What is the mechanism of action of this drug?
Your Answer: Inhibit 30S subunit of ribosomes
Correct Answer: Inhibit 50S subunit of ribosomes
Explanation:Erythromycin is a bacteriostatic antibiotic. This means it stops the further growth of bacteria rather than directly destroying it. This is achieved by inhibiting protein synthesis. Erythromycin binds to the 23S ribosomal RNA molecule in the 50S subunit of the bacterial ribosome. This causes a blockage in the exiting of the peptide chain that is growing. Given that humans have 40S and 60S subunits, and do not have 50S subunits, erythromycin does not affect protein synthesis in human tissues.
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This question is part of the following fields:
- Clinical Sciences
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Question 11
Incorrect
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A case-control study is being designed to look at the relationship between eczema and a new vaccine for yellow fever. What is the usual outcome measure in a case-control study?
Your Answer: Relative risk
Correct Answer: Odds ratio
Explanation:A case–control study (also known as case–referent study) is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case–control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that condition/disease (the cases) with patients who do not have the condition/disease but are otherwise similar (the controls).
An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of A in the presence of B and the odds of A in the absence of B or vice versa. -
This question is part of the following fields:
- Clinical Sciences
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Question 12
Incorrect
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Choose the hormone secreted only by the adrenal medulla:
Your Answer: Metadrenaline
Correct 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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Question 13
Correct
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A literature review of a number of studies was conducted to assess the potential efficacy of a new drug, which may reduce the chance of patients with chronic kidney disease (CKD) developing gout. In one study 120 out of 1,200 patients receiving the new drug developed gout. The total number of the patients were 2,000 and the remaining 800 individuals received a placebo. From the patients that had received the placebo, 200 developed gout. What is the absolute risk reduction of developing gout?
Your Answer: 15%
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) = 0.15 = 15%
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This question is part of the following fields:
- Clinical Sciences
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Question 14
Correct
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Which one of the following statements regarding interleukin 1 (IL-1) is true?
Your Answer: It is released mainly by macrophages/monocytes
Explanation:Interleukin 1 alpha and interleukin 1 beta (IL1 alpha and IL1 beta) are cytokines that participate in the regulation of immune responses, inflammatory reactions, and hematopoiesis. It is secreted mainly by macrophages and monocytes and acts as a costimulator of T cell and B cell proliferation.
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This question is part of the following fields:
- Clinical Sciences
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Question 15
Incorrect
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A study's objective is to find the normal reference range for IgE levels in the adult population. What percentage of individuals will have IgE levels higher than 2 standard deviations from the mean, assuming that the IgE levels follow a normal distribution?
Your Answer: 5%
Correct Answer: 2.30%
Explanation:Normal distribution describes the spread of many biological and clinical measurements. Usually, 68.3% lies within 1 standard deviation (SD) of the mean, 95.4% lies within 2 SD of the mean and 99.7% lies within 3 SD of the mean.
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This question is part of the following fields:
- Clinical Sciences
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Question 16
Correct
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A 45-year-old male patient presents with severe pharyngitis and dysphagia. He's found to be HIV positive and with oesophageal candidiasis. Which of the following regarding HIV virus is correct?
Your Answer: HIV is an RNA virus
Explanation:The human immunodeficiency virus (HIV) is grouped to the genus Lentivirus within the family of Retroviridae, subfamily Orthoretrovirinae. The HIV genome consists of two identical single-stranded RNA molecules that are enclosed within the core of the virus particle. The genome of the HIV provirus, also known as proviral DNA, is generated by the reverse transcription of the viral RNA genome into DNA, degradation of the RNA and integration of the double-stranded HIV DNA into the human genome.
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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 stage in the cell cycle that vincristine acts on:
Your Answer: M
Explanation:Vincristine is part of the antimitotic agents, cell cycle specific (M phase). It binds to microtubules in the spindle apparatus and prevents their proper function, finally arresting mitosis.
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This question is part of the following fields:
- Clinical Sciences
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Question 18
Incorrect
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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: Tetralogy of Fallot
Correct 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 19
Incorrect
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A 21-year-old man presents with a three day history of general malaise and low-grade temperature. Yesterday he developed extensive painful ulceration of his mouth and gums. On examination his temperature is 37.4ºC, pulse 84 / min and there is submandibular lymphadenopathy. What is the most likely diagnosis?
Your Answer: Epstein Barr virus
Correct Answer: Herpes simplex virus infection
Explanation:This man has gingivostomatitis, a characteristic feature of primary herpes simplex virus infection. Herpetic gingivostomatitis is often the initial presentation during the first (primary) herpes simplex infection. It is of greater severity than herpes labialis (cold sores) which is often the subsequent presentations. Primary herpetic gingivostomatitis is the most common viral infection of the mouth.
Primary herpetic gingivostomatitis (PHGS) is caused predominantly by HSV-1 and affects mainly children. Prodromal symptoms, such as fever, anorexia, irritability, malaise and headache, may occur in advance of disease. Sub-mandibular lymphadenitis, halitosis and refusal to drink are usual concomitant findings. -
This question is part of the following fields:
- Clinical Sciences
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Question 20
Incorrect
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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: 15%
Correct 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 21
Correct
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A new study was developed to assess the benefit of omega-3 fish oils in patients with established ischaemic heart disease. The power of the study is equal to:
Your Answer: 1 - probability of making a type II error
Explanation:The power of a test is defined as 1 − the probability of Type II error. The Type II error is concluding at no difference (the null is not rejected) when in fact there is a difference, and its probability is named β. Therefore, the power of a study reflects the probability of detecting a difference when this difference exists. It is also very important to medical research that studies are planned with an adequate power so that meaningful conclusions can be issued if no statistical difference has been shown between the treatments compared. More power means less risk for Type II errors and more chances to detect a difference when it exists.
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This question is part of the following fields:
- Clinical Sciences
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Question 22
Correct
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A study is done on 1000 patients to assess the specificity of a new rapid finger-prick blood test developed to help diagnose deep vein thrombosis (DVT). The new test was positive on 200 patients with DVT and on 100 patients without DVT. It was also negative on 20 patients with DVT and 680 without DVT. What is the specificity of the new test?
Your Answer: 680/780
Explanation:Specificity (negative in health)
The ability of a test to correctly classify an individual as disease- free is called the test′s specificity. [Table 2]Specificity = d / b+d
= d (true negative) / b+d (true negative + false positive)
= Probability of being test negative when disease absent.
Example: One hundred persons with normal angles (diagnosed by ′gold standard′: gonioscopy) are examined by peripheral angle chamber depth examination. Eighty-five persons had normal peripheral angle chamber depth [Table 3]. The specificity of the peripheral angle chamber depth examination to PACG is therefore –
85 / 100 = 85%.
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This question is part of the following fields:
- Clinical Sciences
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Question 23
Correct
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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 24
Incorrect
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Intracellular proteins tagged with ubiquitination are destined to which of the following organelles?
Your Answer: Peroxisome
Correct Answer: Proteasome
Explanation:Delivery of ubiquitinated substrates to the proteasome.
Ubiquitinated proteins are delivered to the proteasome by various routes and the complete picture of how these pathways fit together has yet to emerge, reviewed in. Some substrates bind directly to the proteasome by interacting with the 19S regulatory particle subunits Rpn1028 or Rpn1329, and probably Rpt530. Alternatively, ubiquitinated substrates can be brought to the proteasome by adaptors that bind both the proteasome and the ubiquitin chain on the substrate to deliver it for degradation. -
This question is part of the following fields:
- Clinical Sciences
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Question 25
Incorrect
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Which one of the following statements regarding nitric oxide is incorrect?
Your Answer: Raises intracellular cGMP levels
Correct Answer: Promotes platelet aggregation
Explanation:Nitric oxide, known as an endothelium-derived relaxing factor (EDRF), is biosynthesized endogenously from L-arginine, oxygen, and NADPH by various nitric oxide synthase (NOS) enzymes and is a signaling molecule in many physiological and pathological processes in humans.
One of the main enzymatic targets of nitric oxide is guanylyl cyclase. The binding of nitric oxide to the haem region of the enzyme leads to activation, in the presence of iron. -
This question is part of the following fields:
- Clinical Sciences
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Question 26
Correct
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A 54-year-old female patient presents with a one week history of bloody diarrhoea, fever and abdominal pain. She has a history of rheumatoid arthritis which she controls with methotrexate. Her stool sample shows Campylobacter jejuni. What is the single most appropriate management?
Your Answer: Fluids + clarithromycin
Explanation:This woman is receiving methotrexate, an immunosuppressant, to control her rheumatoid arthritis. In such immunocompromised patients, BNF suggests clarithromycin as first-line management.
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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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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 28
Correct
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Choose the most important stimulator of the central chemoreceptors:
Your Answer: Decrease in pH
Explanation:Central chemoreception refers to the detection of changes in CO2/H+ within the brain and the associated effects on breathing. In the conscious animal the response of ventilation to changes in the brain’s interstitial fluid (ISF) pH is very sensitive. Note that a small change in cerebrospinal fluid (CSF) pH from 7.30 to 7.25 is associated with a doubling of alveolar ventilation; it is a very sensitive reflex response. Note also that the relationship of alveolar ventilation to ISF pH is essentially the same for both types of stimulation, metabolic acid-base disorders and primary CO2 stimulation.
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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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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 30
Correct
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What do T-helper cells of the Th2 subset typically secrete?
Your Answer: IL-4, IL-5, IL-6, IL-10, IL-13
Explanation:Interleukin-4 (IL-4), IL-5 and IL-13, the signature cytokines that are produced during type 2 immune responses, are critical for protective immunity against infections of extracellular parasites and are responsible for asthma and many other allergic inflammatory diseases. Although many immune cell types within the myeloid lineage compartment including basophils, eosinophils and mast cells are capable of producing at least one of these cytokines, the production of these “type 2 immune response-related” cytokines by lymphoid lineages, CD4 T helper 2 (Th2) cells and type 2 innate lymphoid cells (ILC2s) in particular, are the central events during type 2 immune responses.
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This question is part of the following fields:
- Clinical Sciences
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Question 31
Correct
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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 32
Correct
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A new blood test developed to screen individuals for cardiac failure was performed on 500 patients. The results were positive for 40 out of 50 patients with echocardiography-established heart failure. However, the test was also positive for 20 patients with no signs of heart failure. What is the positive predictive value of the test?
Your Answer: 0.66
Explanation:Positive predictive value = TP (true positives) / [TP + FP (false positives)] = 40 / (40 + 20) = 0.66
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This question is part of the following fields:
- Clinical Sciences
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Question 33
Correct
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A 61-year-old female presents to the A&E with malaise and muscle twitching. Her blood pressure is 114/78 mmHg and her pulse is 84/min. Blood exam reveals Calcium = 1.94 mmol/l and Albumin = 38 g/l. Which of the following tests is most useful in establishing her diagnosis?
Your Answer: Parathyroid hormone
Explanation:Hypocalcaemia occurs in patients with impaired function of the parathyroid glands. This is most common after thyroid or parathyroid surgery, but it can be idiopathic—mostly in young adults and less often as part of a genetic syndrome, such as autoimmune polyglandular syndrome type 1. Usually, the first and most useful test to perform in such cases is the measurement of the parathyroid hormone.
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This question is part of the following fields:
- Clinical Sciences
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Question 34
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 35
Correct
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A 23-year-old man is referred to the pneumologist with a suspicion of bronchiectasis. History reveals he's been having recurrent pulmonary infections his whole life together with difficulties gaining weight. He's a non-smoker with a clear family history and he admits inhalers haven't helped him in the past. He is finally suspected of having cystic fibrosis. What is the normal function of the cystic fibrosis transmembrane regulator?
Your Answer: Chloride channel
Explanation:Chloride channels are involved in a diverse set of functions in normal physiology and acquired diseases. Additionally, there are genetic diseases caused by mutations in chloride channels (channelopathies) — the most common being cystic fibrosis, which has a prevalence of 1 in 2,000 Caucasians.
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This question is part of the following fields:
- Clinical Sciences
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Question 36
Incorrect
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What percentage of values lie within 3 standard deviations of the mean in a normal distribution?
Your Answer: 97.20%
Correct Answer: 99.70%
Explanation:Normal distribution describes the spread of many biological and clinical measurements. Usually, 68.3% lies within 1 standard deviation (SD) of the mean, 95.4% lies within 2 SD of the mean and 99.7% lies within 3 SD of the mean.
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This question is part of the following fields:
- Clinical Sciences
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Question 37
Incorrect
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Which is the best source of vitamin D per average serving for a woman with suspected Osteomalacia?
Your Answer: Sunflower seeds
Correct Answer: Cod liver oil
Explanation:Serum vitamin D levels are influenced by sun exposure and diet. Cod liver oil is an important dietary vitamin D source in high-latitude countries like Norway where there is no sun-induced vitamin D production during the winter. 14 Norwegian Health Authorities have recommended 5 ml of cod liver oil daily (400 IU of vitamin D) for more than 60 years to prevent diseases like rickets, formerly more prevalent in areas with little access to vitamin D-rich fatty fish.
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This question is part of the following fields:
- Clinical Sciences
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Question 38
Incorrect
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Which one of the following congenital infections is most characteristically associated with chorioretinitis?
Your Answer: Cytomegalovirus
Correct Answer: Toxoplasma gondii
Explanation:The common congenital infections encountered are rubella, toxoplasmosis and cytomegalovirus. Cytomegalovirus is the most common congenital infection in the UK. Maternal infection is usually asymptomatic.
Congenital toxoplasmosis is associated with fetal death and abortion, and in infants, it is associated with neurologic deficits, neurocognitive deficits, and chorioretinitis. -
This question is part of the following fields:
- Clinical Sciences
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Question 39
Incorrect
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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:
Correct 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 40
Incorrect
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Which one of the following statements regarding mitochondrial inheritance is true?
Your Answer:
Correct Answer: Poor genotype:phenotype correlation
Explanation:The human cell has two type of DNA: Nuclear DNA and Mitochondrial DNA (MtDNA). A MtDNA copy is passed down entirely unchanged, through the maternal line. Males cannot pass their MtDNA to their offspring although they inherit a copy of it from their mother. There is poor genotype:phenotype correlation. Within a tissue or cell there can be different mitochondrial populations (this is known as heteroplasmy).
Examples of mitochondrial diseases include:
– Leber’s optic atrophy
– MELAS syndrome (mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes)
– MERRF syndrome (myoclonus epilepsy with ragged-red fibres)
– Kearns-Sayre syndrome (more severe syndromic variant of chronic progressive external ophthalmoplegia, onset in patients < 20 years old) -
This question is part of the following fields:
- Clinical Sciences
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Question 41
Incorrect
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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:
Correct 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 42
Incorrect
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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:
Correct 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 43
Incorrect
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A 40-year-old female patient with a history of rheumatoid arthritis is diagnosed with type 1 renal tubular acidosis. What is the most probable sequela of this condition?
Your Answer:
Correct Answer: Nephrocalcinosis
Explanation:Distal renal tubular acidosis is due to defective proton secretion from the alpha intercalated cells of the distal tubule caused by dysfunction of the H+/K+ antiporter on the apical membrane. This leads to failure of H+ excretion thereby causing systemic acidosis and potassium depletion. Inability to lower the urine pH below 5.3 in the presence of systemic acidosis is the diagnostic hallmark of type I or distal renal tubular acidosis. Hypercalciuria, hypocitraturia and elevated urinary pH observed in distal renal tubular acidosis can lead to nephrocalcinosis and may cause renal calculi, obstructive uropathy and renal failure necessitating surgical or endoscopic stone extraction.
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This question is part of the following fields:
- Clinical Sciences
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Question 44
Incorrect
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The average weight of 64 patients with type 2 diabetes mellitus was 81 kg, with a standard deviation of 12 kg. What is the standard error of the mean?
Your Answer:
Correct Answer: 1.5
Explanation:The SEM is dependent on the variation in the population and the number of the extracted samples. A large variation in the population causes a large difference in the sample means, ultimately resulting in a larger SEM. However, as more samples are extracted from the population, the sample means move closer to the population mean, which results in a smaller SEM. In short, the SEM is an indicator of how close the sample mean is to the population mean. Standard error of the mean = standard deviation / square root (number of patients)
The standard error of the mean is calculated by the standard deviation / square root (number of patients)= 12 / square root (64) = 12 / 8 = 1.5
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This question is part of the following fields:
- Clinical Sciences
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Question 45
Incorrect
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Double-stranded DNA is found in which of the following cell organelles?
Your Answer:
Correct Answer: Mitochondria
Explanation:Mitochondrial DNA (mtDNA) is a double-stranded molecule of 16.6 kb (Figure 1, lower panel). The two strands of mtDNA differ in their base composition, with one being rich in guanines, making it possible to separate a heavy (H) and a light (L) strand by density centrifugation in alkaline CsCl2 gradients.
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This question is part of the following fields:
- Clinical Sciences
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Question 46
Incorrect
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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:
Correct 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 47
Incorrect
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A 23-year-old male patient with a downward dislocation of the lens in his right eye is experiencing visual problems. The ophthalmologist notes a constellation of symptoms resembling those of Marfan Syndrome. The patient's history reveals learning disabilities and a diagnosis of homocystinuria is suspected. What is the pathophysiology of homocystinuria?
Your Answer:
Correct Answer: Deficiency of cystathionine beta synthase
Explanation:Inherited metabolic disorders are often characterized by the lack of an essential enzyme and are currently treated by dietary restriction and other strategies to replace the substrates or products of the missing enzyme. Patients with homocystinuria lack the enzyme cystathionine β-synthase (CBS), and many of these individuals do not respond to current treatment protocols.
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This question is part of the following fields:
- Clinical Sciences
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Question 48
Incorrect
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A 34-year-old man presents with haemoptysis and weight loss. History reveals he suffers from night sweats and upon auscultation you notice reduced breath sounds over the apex of his right lung and significant nail clubbing. You refer him to a pneumologist who administers the following antibiotics: rifampicin, ethambutol, pyrazinamide and isoniazid. What is the mechanism of action of the first drug?
Your Answer:
Correct Answer: Inhibit RNA synthesis
Explanation:Rifampicin specifically inhibits bacterial RNA polymerase, the enzyme responsible for DNA transcription, by forming a stable drug-enzyme complex with a binding constant of 10(-9) M at 37 C.
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This question is part of the following fields:
- Clinical Sciences
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Question 49
Incorrect
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Which one of the following is true regarding Escherichia coli infection?
Your Answer:
Correct Answer: E coli is an important cause of neonatal meningitis
Explanation:Escherichia coli (also known as E. coli) is a gram-negative, facultatively anaerobic, rod-shaped bacterium commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in their hosts, and are occasionally responsible for product recalls due to food contamination. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2, and preventing colonization of the intestine with pathogenic bacteria. Virulent strains can cause gastroenteritis, urinary tract infections, and neonatal meningitis.
The most common causes of neonatal meningitis is bacterial infection of the blood, known as bacteremia (specifically Group B Streptococci (GBS; Streptococcus agalactiae), Escherichia coli, and Listeria monocytogenes). Although there is a low mortality rate in developed countries, there is a 50% prevalence rate of neurodevelopmental disabilities in E. coli and GBS meningitis -
This question is part of the following fields:
- Clinical Sciences
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Question 50
Incorrect
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What is the correct formula to calculate the positive predictive value? (TP = true positive; FP = false positive; TN = true negative; FN = false negative)
Your Answer:
Correct Answer: TP / (TP + FP)
Explanation:Positive predictive value is the probability that subjects with a positive screening test truly have the disease.
Positive predictive value = true positive / ( true positive + false positive)
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This question is part of the following fields:
- Clinical Sciences
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