A nurse who is known to have an allergy to latex develops a widespread urticarial rash and facial oedema shortly after eating lunch.
Which food is she most likely to have consumed?
Correct Answer E:
The nurse is likely to suffer from latex-fruit syndrome.
Latex allergy:
Sensitivity to latex may cause a number of problems:
Latex allergy is more common in children with myelomeningocele spina bifida.
Latex-fruit syndrome:
It is recognized that many people who are allergic to latex are also allergic to fruits, particularly banana, pineapple, avocado, chestnut, kiwi fruit, mango, passion fruit and strawberry.
A study is performed to find the normal reference range for IgE levels in adults. Assuming IgE levels follow a normal distribution, what percentage of adults will have an IgE level higher than 2 standard deviations from the mean?
Correct Answer B:
For normally distributed data 95.4% of values lie within 2 standard deviations of the mean, leaving 4.6% outside this range. Therefore 2.3% of values will be higher and 2.3% will be lower than 2 standard deviations from the mean. This figure is sometimes approximated to 2.5%.
Normal distribution:
The normal distribution is also known as the Gaussian distribution or 'bell-shaped' distribution. It describes the spread of many biological and clinical measurements.
Properties of the Normal distribution:
Standard deviation:
An elderly patient with a history of atrial fibrillation develops torsades de pointes shortly after being started on sotalol.
What effect does sotalol have on the cardiac cell membrane to make this more likely?
Correct Answer C:
Long QT syndrome - usually due to loss-of-function/blockage of K+ channels.
This patient is likely to have developed torsades de pointes secondary to a prolonged QT interval.
Long QT syndrome:
Long QT syndrome (LQTS) is an inherited condition associated with delayed repolarization of the ventricles. It is important to recognize as it may lead to ventricular tachycardia and can therefore cause collapse/sudden death.
The most common variants of LQTS (LQT1 & LQT2) are caused by defects in the alpha subunit of the slow delayed rectifier potassium channel. A normal corrected QT interval is less than 430 ms in males and 450 ms in females.
Causes of a prolonged QT interval:
Features:
Management:
*The usual mechanism by which drugs prolong the QT interval is blockage of potassium channels. See the link for more details
**A non-sedating antihistamine and classic cause of prolonged QT in a patient, especially if also taking P450 enzyme inhibitor, e.g. Patient with a cold takes terfenadine and erythromycin at the same time
***Note sotalol may exacerbate long QT syndrome
Which one of the following diseases is most strongly associated with HLA antigen DR2?
HLA associations: HLA antigens are encoded for by genes on chromosome 6. HLA A, B and C are class I antigens whilst DP, DQ, DR are class II antigens. Questions are often based around which diseases have strong HLA associations. The most important associations are listed below:
HLA-A3:
HLA-B5:
HLA-B27:
HLA-DQ2/DQ8:
HLA-DR2:
HLA-DR3:
HLA-DR4:
*Type 1 diabetes mellitus is associated with HLA-DR3 but is more strongly associated with HLA-DR4.
Patients with deficiencies of which one of the following complement protein(s) are predisposed to immune complex diseases?
Complement deficiencies: Complement is a series of proteins that circulate in plasma and are involved in the inflammatory and immune reaction of the body. Complement proteins are involved in chemotaxis, cell lysis and opsonization.
C1 inhibitor (C1-INH) protein deficiency:
C1q, C1rs, C2, C4 deficiency (classical pathway components):
C3 deficiency:
C5 deficiency:
C5-9 deficiency:
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