Which one of the following best describes the main action of the polymerase chain reaction?
Correct Answer B:
PCR:
Polymerase chain reaction (PCR) is a molecular genetic investigation technique. 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. PCR is also extensively used in forensics. Prior to the procedure it is necessary to have two DNA oligonucleotide primers.
These are complimentary to specific DNA sequences at either end of the target DNA Initial prep:
The following cycle then takes place:
The above cycle is then repeated, with the amount of DNA doubling each time.
Reverse transcriptase PCR:
Which one of the following would cause a fall in the carbon monoxide transfer factor (TLCO)?
Correct Answer E:
Transfer factor:
Transfer factor: The transfer factor describes the rate at which a gas will diffuse from alveoli into blood. Carbon monoxide is used to test the rate of diffusion. Results may be given as the total gas transfer (TLCO) or that corrected for lung volume (transfer coefficient, KCO).
KCO also tends to increase with age. Some conditions may cause an increased KCO with a normal or reduced TLCO:
In which one of the following conditions is intravenous immunoglobulin therapy most likely to be beneficial?
Immunoglobulins: therapeutics: The Department of Health issued guidelines on the use of intravenous immunoglobulins in May 2008
Uses:
Basics:
A 37-year-old woman who has a BMI of 44 kg/m2 undergoes a Roux-en-Y gastric bypass.
Of which vitamin/mineral is she most likely to require supplementation?
Correct Answer B: The duodenum is the primary site of absorption for both iron and calcium. All gastric bypass operations bypass the duodenum. Nearly all menstruating women will therefore require iron supplementation.
Obesity: bariatric surgery:
The use of bariatric surgery in the management of obesity has developed significantly over the past decade. It is now recognized that for many obese patients who fail to lose weight with lifestyle and drug interventions the risks and expense of long-term obesity outweigh those of surgery.
NICE guidelines on bariatric surgery for adults: Consider surgery for people with severe obesity if:
Consider surgery as a first-line option for adults with a BMI of more than 50 kg/m2 in whom surgical intervention is considered appropriate; consider orlistat before surgery if the waiting time is long.
Types of bariatric surgery:
Which operation?
A study is performed looking at the chance of stroke in high-risk patients taking a new oral antithrombotic drug compared to warfarin. The following results are obtained:
What is the relative risk of having a stroke within a 3 year period for patients taking the new drug compared to warfarin?
Correct Answer D:
Relative risk = EER / CER
Relative risk: Relative risk (RR) is the ratio of risk in the experimental group (experimental event rate, EER) to risk in the control group (control event rate, CER). The term relative risk ratio is sometimes used instead of relative risk. To recap:
For example, if we look at a trial comparing the use of paracetamol for dysmenorrhoea compared to placebo we may get the following results:
If the risk ratio is > 1 then the rate of an event (in this case experiencing significant pain relief) is increased compared to controls. It is therefore appropriate to calculate the relative risk increase if necessary.
If the risk ratio is < 1 then the rate of an event is decreased compared to controls. The relative risk reduction should therefore be calculated.
Relative risk reduction (RRR) or relative risk increase (RRI) is calculated by dividing the absolute risk change by the control event rate: Using the above data, RRI = (EER - CER) / CER = (0.6 - 0.25) / 0.25 = 1.4 = 140%
Click to expand