Wednesday, 31 October 2012

A 28-year-old woman who is known to have a cardiac murmur becomes pregnant. It is noted that the intensity of her murmur diminishes during her pregnancy. Which cardiac abnormality is she likely to have?

A. Aortic stenosis
B. Aortic regurgitation
C. Mitral stenosis
D. Pulmonic stenosis
E. Fallot’s tetralogy

The correct answer is B. During pregnancy, cardiac output and blood volume increase from the second month up to the thirtieth week to 30–50% above the normal levels. The average increase in blood volume during pregnancy amounts to 1600 ml, and there is also an increased metabolic workload. This produces warm extremities, a tachycardia with a large-volume pulse and a slight rise in venous pressure. The diastolic blood pressure is lower due to vasodilatation, and this is responsible for the fading of the aortic regurgitation murmur. The apex beat is displaced, because of cardiomegaly and a raised diaphragm. The increased blood flow may produce a pulmonary systolic murmur and a third heart sound. All stenotic murmurs become more prominent.

A 51-year-old baby-sitter sustained a fracture in her right wrist after an apparently minor fall. Her dorsal spine is kyphotic. Her blood biochemical profile is normal. You are thinking of osteoporosis and planning to perform DEXA scan. Indications for bone mineral density measurement include all of the following, except?

a- Previous low trauma fracture.
b- Family history of osteoporotic fracture.
c- Systemic diseases associated with high risk of osteoporosis like rheumatoid arthritis.
d- A patient on long term prednisolone treatment.
e- Body mass index of more than 23.

The correct answer is e.
  • a - with a fall from standing height or less.
  • b - also, radiological evidence of osteoporosis, and premature gonadal failure.
  • c - remember, not only the disease may pose a risk but also its treatment like corticosteroids.
  • d - also, clinical features of osteoporosis, like loss of height and kyphosis.
  • e -false, BMI less than 19; hence obese persons are usually protected.
Polycystic ovarian syndrome patients although may be infertile with irregular or absent menstrual cycles, but the high BMI and the good amount of estrogens and androgens protect them from osteoporosis. Measurement of BMD is valuable not only for diagnosis but also for management of osteoporosis, since the anti-fracture efficacy of many treatments is restricted to individuals who have low spine or hip BMD values. BMD measurements are also used to assess treatment response. Since changes in BMD with most osteoporosis treatments are small and occur slowly, repeat measurements
should not be performed until 12-24 months after starting therapy. Measurement of spine BMD is better than hip BMD for assessing treatment response because precision is better and changes in BMD at the spine occur more quickly because of the higher content of trabecular bone.

A 56-year-old retired bus driver presents with symmetrical deforming arthropathy. His rheumatoid factor is positive at a very high titer. Regarding rheumatoid factor; all of the following are true, except?

a- Is an antibody directed against Fc portion of IgG.
b- May be of IgG, IgM, or IgA class.
c- Is diagnostic of rheumatoid arthritis.
d- Can be detected by many lab methods.
e- Found in almost 100% of cases of secondary Sjogren's syndrome and Felty’s syndrome.

The correct answer is c.
  • a - true, is an autoantibody.
  • b - but, we detect only IgM in the slide agglutination test.
  • c - false; does not reflect any thing apart from poor prognosis if found in high titer in RA.
  • d - like slide tube agglutination, SCAT, and Rose Waaler tests. e-true; these are seropositive.
In terms of sensitivity, it is present in the majority of patients with erosive rheumatoid disease but may only appear after months or years of disease, once the diagnosis is beyond dispute. It is therefore neither sufficient nor necessary for the diagnosis. Its principal use is as a prognostic marker; a high titer at the onset of rheumatoid arthritis associates with a poorer prognosis. IgG rheumatoid factor has greater specificity for major rheumatic disease but the above caveats still remain.

Tuesday, 30 October 2012

Sexual function is controlled by which nucleus of hypothalamus?

Option A: Supraoptic nucleus
Option B: Paraoptic nucleus
Option C: Lateral hypothalamus
Option D: Posterior hypothalamus

The correct answer is C. The ideal answer is preoptic nucleus. The preoptic area is one of the areas of greatest sexual dimorphism. Several hypothalamic nuclei are sexually dimorphic, i.e. there are clear differences in both structure and function between males and females. Some differences are apparent even in gross neuroanatomy: most notable is the sexually dimorphic nucleus within the preoptic area. However most of the differences are subtle changes in the connectivity and chemical sensitivity of particular sets of neurons.

General Adaptation syndrome is seen in?

Option A: Depression
Option B: Anxiety
Option C: Panic attack
Option D: Stressful situation

The correct answer is D. Stressful situation.

  • Hans Selye developed a model of stress that he called the general adaptation syndrome. 
  • It consisted of three phases: (1) the alarm reaction; (2) the stage of resistance, in which adaptation is ideally achieved; and (3) the stage of exhaustion, in which acquired adaptation or resistance may be lost. 
  • He considered stress a nonspecific bodily response to any demand caused by either pleasant or unpleasant conditions. 
  • Selye believed that stress, by definition, need not always be unpleasant. He called unpleasant stress distress while pleasent stress eustress. Accepting both types of stress requires adaptation. 
  • The body reacts to stress defined as anything (real, symbolic, or imagined) that threatens an individual's survival by putting into motion a set of responses that seeks to diminish the impact of the stressor and restore homeostasis. 
  • Many stressors occur over a prolonged period of time or have long-lasting repercussions. For example, the loss of a spouse may be followed by months or years of loneliness and a violent sexual assault may be followed by years of apprehension and worry. Neuroendocrine and immune responses to such events help explain why and how stress can have deleterious effects.

All are true about Clozapine except:

Option A: More potently block D2 compared to D1.
Option B: Blood level above 350 mg/ml associate with better response
Option C: Should not be used with Carbamazepine concurrently
Option D: Should be discontinued if the WBC count is below 3,000/mm3 cells

The correct answer is A.

More potently block D2 compared to D1. (Kaplan & Sadock synopsis of psychiatry, 10th edition, page 1095-1096)

  • Clozapine is an antagonist of 5-HT2A, D1, D3, D4, and alpha1 receptors. It has relatively low potency as a D2-receptor antagonist. Data from PET scanning show that 10 mg of haloperidol produces 80 percent occupancy of striatal D2 receptors, whereas clinically effective dosages of clozapine occupy only 40 to 50 percent of striatal D2 receptors. 
  • This difference in D2 receptor occupancy is probably why clozapine does not cause extrapyramidal adverse effects. 
  • It has also been postulated that clozapine, as well as other SDAs, bind more loosely to the D2 receptor, and as a result of this fast dissociation, more normal dopamine neurotransmission is possible. 

Sunday, 28 October 2012

Which of the following is the most important first step in the diagnostic and treatment process?

Option A: A through history and physical examination
Option B: Blood Work
Option C: Urinalysis
Option D: Electrocardiogram
Option E: Radiographic Imaging
Option F: Invasive Procedures

The answer is a. A thorough history and physical examination is the core of the diagnostic and treatment process. Any further assessment with blood work and the other tests listed must be integrated with the initial information compiled in the history and physical examination. The H&P is always the most important first step in any diagnostic and treatment process.

The normal amount of CSF in a man is about

Option A: 50 cc
Option B: 100 cc
Option C: 150 cc
Option D: 200 cc

The correct answer is C. Cerebrospinal fluid (CSF) is a clear colorless bodily fluid produced in the choroid plexus of the brain. It acts as a cushion or buffer for the cortex, providing a basic mechanical and immunological protection to the brain inside the skull and serves a vital function in cerebral autoregulation of cerebral blood flow. The CSF occupies the subarachnoid space - between the arachnoid mater and the pia mater, and the ventricular system around and inside the brain and spinal cord. It constitutes the content of the ventricles, cisterns, and sulci of the brain, as well as the central canal of the spinal cord.
CSF serves four primary purposes:
  • Buoyancy: The actual mass of the human brain is about 1400 grams; however, the net weight of the brain suspended in the CSF is equivalent to a mass of 25 grams. The brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight, which would cut off blood supply and kill neurons in the lower sections without CSF.
  • Chemical stability: CSF flows throughout the inner ventricular system in the brain and is absorbed back into the bloodstream, rinsing the metabolic waste from the central nervous system through the blood–brain barrier. This allows for homeostatic regulation of the distribution of neuroendocrine factors, to which slight changes can cause problems or damage to the nervous system. For example, high glycine concentration disrupts temperature and blood pressure control, and high CSF pH causes dizziness and syncope.. To use Davson's term, the CSF has a "sink action" by which the various substances formed in the nervous tissue during its metabolic activity diffuse rapidly into the CSF and are thus removed into the bloodstream as CSF is absorbed.
  • Protection: CSF protects the brain tissue from injury when jolted or hit. In certain situations such as auto accidents or sports injuries, the CSF cannot protect the brain from forced contact with the skull case, causing hemorrhaging, brain damage, and sometimes death.
  • Prevention of brain ischemia: The prevention of brain ischemia is made by decreasing the amount of CSF in the limited space inside the skull. This decreases total pressure and facilitates brain blood flow - perfusion.

Mapleson's classification of anaesthetic breathing systems

Option A: Describes four systems, A, B, C and D
Option B: Classifies the Bain system as maples on D
Option C: Describes the T-piece as mapleson D
Option D: Describes the T-piece as requiring a fresh gas-flow of 1.5-2 times

The Correct answer is B. Anaesthetic gas exits the anaesthesia machine (via the common gas outlet) and then enters a breathing circuit. The function of the circuit is to deliver oxygen and anaesthetic gases to the patient and to eliminate CO2. The CO2 may be eliminated by gas inflow or by soda lime absorption. Various classification systems have been developed to aid understanding of how breathing systems operate.
  • Open, semi-open, semi-closed and closed
  • Non-rebreathing and rebreathing systems
  • Mapleson systems
  • Adjustable pressure-limiting valve (APL valve)
Mapleson described five different arrangements of breathing circuits. He classifed these circuits and they are now known as the Mapleson systems, termed A-E. This classification does not include systems with CO2 absorption.