CSGD Quiz 3 2006

1

Which ONE of the following statements regarding nicotine is CORRECT?


  There is rapid tolerance to the peripheral actions of nicotine due to a decrease in acetylcholine release from preganglionic nerves.

  Chronic use of nicotine leads to a decrease in nicotinic receptors in the brain.

  Part of the physical withdrawal response to nicotine is anorexia.

  Nicotine may cause both an increase in alertness and relief from tension.

  Nicotine is an agonist at GABA receptors.


A is incorrect: Peripheral tolerance is rapid, but nicotine causes an increase in ACh from preganglionic nerves via its actions on the adrenal medulla. B is incorrect: Chronic use will increase the number of receptors in the brain. C is incorrect: Withdrawal is often associated with an increased appetite. D is correct: This is one of the factors that leads to the addictive nature of nicotine. E is incorrect: It is an agonist at nicotinic muscarinic receptors.

2

The antidepressant drug moclobemide is considered less likely to have the “cheese reaction” as a side effect than earlier monamine oxidase inhibitors. Which ONE of the following statements is the CORRECT explanation?


  Moclobemide is selective for monoamine oxidase A.

  Moclobemide is selective for monoamine oxidase B.

  Moclobemide competes with dietary amines for uptake across the gastrointestinal tract.

  Moclobemide is a reversible inhibitor of monamine oxidase.

  Moclobemide inhibits neuronal uptake of monoamines.


A is incorrect: This statement is true, but is not closely associated with the cheese reaction. B is incorrect: Moclobemide is MAO-A selective. C is incorrect: It inhibits the metabolism of amines. It does not compete for uptake. D is correct: It is this reversibility which is thought to mitigate the build-up of tyramine associated with the cheese reaction. E is incorrect: It does not affect neuronal uptake.

3

Which ONE of the following drugs that can be used to alleviate anxiety has as their primary site of action a target outside the central nervous system?


  The 5-HT1A receptor partial agonist, buspirone.

  The b-adrenoceptor antagonist, propranolol.

  The benzodiazepine, diazepam.

  The non-benzodiazepine, zopiclone.

  The barbiturate, phenobarbital.


The only anxiolytics whose primary action is outside the CNS are the β-adrenoceptor antagonists, which work by treating the physical manifestations of anxiety - they inhibit the SNS activation associated with the anxiety "fear response.

4

In the early 1970s a discovery was made: a brief high frequency train of action potentials within specific inter-neuronal pathways leads to an increase in synaptic strength. Which ONE of the following cellular phenomena of relevance to learning and memory was discovered?


  Dendritic propagation in the neocortex.

  Long – term potentiation in the hippocampus.

  Synaptogenesis in the prefrontal cortex.

  Paired – pulse facilitation in the amygdala.

  Synaptic pruning in the thalamus.


The hippocampus is classically associated with LTP. Except for E, all the others describe processes that are part of LTP but in the wrong place. Synaptic pruning was not the mechanism by which LTP was discovered.

5

Which ONE of the following features best differentiates between depression and dementia?


  Rapidity of onset of the disorder.

  Mini-Mental State Examination Score between 21 and 24 out of 30.

  Weight loss.

  Decreased attention to personal care.

  Loss of interest in activities.


A is correct: Dementia onset is usually very slow (insidious - years), compared to depression which is usually gradual (weeks/months).

The other answers are features of both.

6

All of the dementias have areas of the brain specifically targeted by the pathologic process. Which ONE of the following dementias DOES NOT have the listed brain area affected?


  Alzheimer’s disease: temporal and parietal region.

  Fronto-temporal dementia: frontal and temporal region.

  Lewy body dementia: frontal lobe region.

  Dementia associated with Parkinson’s disease: substantia nigra and corpus striatum.

  Dementia associated with Cruetzfeldt-Jakob disease: motor cortical area.


The classic histological appearance of CJD is spongiform change in all six cortical layers of the cerebral cortex. MRI often shows high intensity changes in the basal ganglia.

7

Which ONE of the following statements about ageing is NOT CORRECT?


  Ageing is associated with increased susceptibility to disease.

  The hydra does not age.

  Senescence is the phase of ageing associated with an increased probability of dying.

  All the organ systems age at the same rate.

  The oldest authenticated age at death of a human being is 122 years.


A is correct. B is correct: The hydra genus does actually undergo senescence, although it was previously thought to be immortal. C is correct: Senescence can refer either to biological senscence (cells losing the ability to divide) or organismal senescence (whole-body changes). D is incorrect because organ systems tend to age at different rates. E is correct: Jeanne Calment.

8

Which ONE of the following statements defines a category C drug for use in pregnancy?


  Drugs which have caused an increase in malformations.

  Drugs taken by a limited number of pregnant women in which there is no information about harmful effect.

  Contraindicated.

  Drugs that cause harmful effect which is usually pharmacological and may be reversible.

  Drugs taken by a large number of pregnant women without harmful effect.


A is incorrect: This is the definition of class D drugs. B is incorrect: Not the definition of any class. C is incorrect: Only category X drugs are definitively contraindicated. D is correct: This is the definition of class C drugs. E is incorrect: This the definition of class A drugs.

9

Which ONE of the following prenatal tests is best performed at 14-15 weeks of pregnancy?


  Karyotyping following amniocentesis.

  Karyotyping following chorionic villus sampling.

  Maternal serum screening (quadruple test).

  Ultrasound and nuchal translucency measurements.

  Percutaneous umbilical blood sampling.


A is incorrect: Amniocentesis is usually performed around 15 weeks, but usually only if CVS results are equivocal or unavailable. B is incorrect: CVS is usually done around 11-13 weeks. C is correct: The second trimester serum screen is a non-invasive test that has a high rate of detection for Down syndrome and NTDs. D is incorrect: Nuchal translucency ultrasound is a first trimester screening test. E is incorrect: PUBS is a last-resort option following failed amniocentesis, CVS and ultrasound - it carries significant risks of complication.

10

Which ONE of the following statements about genes or chromosomes is NOT CORRECT?


  Monosomy of autosomal chromosomes in embryos is usually lethal.

  There are specific genes on the long arm of chromosome 21 that, when present in triplicate, are associated with certain features of Down syndrome.

  All genes on one of the X chromosomes in females are transcriptionally silent through a process known as X chromosome inactivation.

  A relatively small number of genes must only have mono-allelic expression.

  Prader-Willi syndrome is caused by a deficiency of certain paternally active genes.


C is incorrect: A small number genes escape inactivation because they require biallelic expression. This is evidenced by Turner/XO syndrome, where the complete absence of one X chromosome causes abnormalities.