In the Gell and Coombs classification of hypersensitivity reactions Grave's disease is an example of a:
Correct Answer E:
Hypersensitivity: The Gell and Coombs classification divides hypersensitivity reactions into 4 types: 1- Type I - Anaphylactic:
2- Type II - Cell bound:
3- Type III - Immune complex:
4- Type IV - Delayed hypersensitivity:
In recent times a further category has been added:
5- Type V - Stimulated hypersensitivity:
A 61-year-old woman is admitted to the Acute Medical Unit as she is generally unwell with muscle twitching. Blood pressure is recorded at 114/78 mmHg, pulse 84/min and she is apyrexial. Blood tests reveal the following:
Which one of the following tests is most useful in elucidating the cause of her symptoms?
Correct Answer D: Parathyroid hormone is the single most useful test in determining the cause of hypocalcaemia.
Hypocalcaemia: causes and management: The clinical history combined with parathyroid hormone levels will reveal the cause of hypocalcaemia in the majority of cases.
Causes:
Acute pancreatitis may also cause hypocalcaemia. Contamination of blood samples with EDTA may also give falsely low calcium levels.
Management:
Which one of the following statements best describes a type II statistical error?
Correct Answer D:
Significance tests: A null hypothesis (H0) states that two treatments are equally effective (and is hence negatively phrased).
A significance test uses the sample data to assess how likely the null hypothesis is to be correct. For example:
The alternative hypothesis (H1) is the opposite of the null hypothesis, i.e. There is a difference between the two treatments.
The p value is the probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true. It is therefore equal to the chance of making a type I error(see below).
Two types of errors may occur when testing the null hypothesis:
The power of a study is the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference:
Which one of the following clotting factors is not affected by warfarin?
Correct Answer C: Warfarin - clotting factors affected mnemonic - 1972 (10, 9, 7, 2).
Factor XII is not affected by warfarin.
Warfarin: Warfarin is an oral anticoagulant which inhibits the reduction of vitamin K to its active hydroquinone form, which in turn acts as a cofactor in the formation of clotting factor II, VII, IX and X (mnemonic = 1972) and protein C .
Indications:
Patients on warfarin are monitored using the INR (international normalized ration), the ratio of the prothrombin time for the patient over the normal prothrombin time. Warfarin has a long half-life and achieving a stable INR may take several days. There a variety of loading regimes and computer software is now often used to alter the dose.
Factors that may potentiate warfarin:
Side-effects:
Which one of the following is involved in the degradation of polypeptides?
Correct Answer C:
Cell organelles: The table below summarizes the main functions of the major cell organelles:
Click to expand