Sunday, 25 November 2012

A 62-year-old woman with a 30-pack-year smoking history is evaluated.

A 62-year-old woman with a 30-pack-year smoking history is evaluated with a history of chronic shortness of breath. She has mild left-sided chest discomfort. She denies fever, chills, and night sweats and has no localizing signs on physical exam. A CT-guided needle biopsy of the lesion seen in the CXR in Fig. below is performed and reveals malignant cells.

Based on the CXR finding, the likely diagnosis is
a. Small cell carcinoma
b. Bronchoalveolar cell carcinoma
c. Adenocarcinoma of the lung
d. Liposarcoma of the chest wall

This malignancy is associated with
a. Positive sputum cytology
b. A good response to chemotherapy
c. Incidentally detected peripheral carcinomas on CXR
d. Cavitation in the majority of these carcinomas

Bilateral lower zone haziness is seen secondary to soft tissue shadows. An irregular 1.5 × 2-cm shadow is noted in the left middle lung zone peripherally abutting the left chest wall

The answers are 6-c, 7-c. An SPN in a 42-year-old smoker mandates a diagnostic workup. In this case, a CT-guided biopsy revealed malignant cells. Adenocarcinoma is commonly peripheral and represents about 30% of the total number of lung cancer cases. Its incidence is rising especially in females. Adenocarcinoma frequently presents as an incidental finding on x-ray. The other major histological types of lung cancer tend to have central localization and are as follows:
  • Squamous (epidermoid) carcinoma. Eighty percent are central; when peripheral, they have a tendency for cavitation.
  • Small cell (oat cell) carcinoma. Believed to originate from neuroendocrine cells of the bronchial mucosa, these are usually central with mediastinal involvement.
  • Large cell undifferentiated carcinoma with mixed malignant features.
  • Bronchoalveolar carcinoma. A variant of adenocarcinoma, these arise from type II pneumocytes in the alveoli. They may simulate pneumonia with focal consolidation or may present as solitary or multiple nodules.

Saturday, 24 November 2012

A 34-year-old woman, a recent immigrant from Eastern Europe, is seen with complaints of vague chest discomfort after an upper respiratory tract infection.

A 34-year-old woman, a recent immigrant from Eastern Europe, is seen with complaints of vague chest discomfort after an upper respiratory tract infection. She is not a smoker and gives a history of BCG vaccination when she was an infant. Physical examination is normal. PPD is 10-mm induration and induced sputum for acid-fast bacilli is negative. CXR is shown below:

What is the most likely diagnosis?
a. Granuloma
b. Scar carcinoma
c. Coccidioidomycosis
d. Hamartoma

What is the next step in the management of this patient?
a. MRI of the chest
b. Fiberoptic bronchoscopy
c. Comparison of previous chest radiograph, if available, and repeat chest radiograph in 3 mo
d. Treatment with four-drug anti-TB chemotherapy

This chest x-ray shows a normal heart size. No pleural or mediastinal disease is noted. Cardiophrenic and costophrenic angles are clear. A dense, rounded solitary pulmonary nodule is noted in the right lung.

The answers are 2-a, 3-c. With a history of a positive PPD in a young immigrant and the presence of a calcified peripheral SPN, the likely diagnosis is tuberculous granuloma. Comparison with a previous x-ray to confirm stability of the lesion would prevent the need for further diagnostic tests. An MRI of the chest would not add definitive information, and bronchoscopy for a peripherally located calcified lesion would be of low yield. Since this lesion probably represents latent, old, healed granulomatous focus, treatment with four antituberculosis drugs is not warranted unless evidence of active disease is seen.

A 40-year-old male smoker presents with a history of chronic cough.

A 40-year-old male smoker presents with a history of chronic cough. He has had symptoms of an upper respiratory illness for a few months since visiting family in Arizona. Physical exam is normal. CXR is shown below in Fig. below. The next step in management should be:

a. Complete pulmonary function tests
b. Fiberoptic bronchoscopy
c. Percutaneous needle biopsy
d. Observation and repeat CXR in 6 to 8 months

This chest x-ray shows a radiographically dense nodule in the left hilum. Cardiophrenic and costophrenic angles are clear. An 0.8 × 1-cm circular solitary pulmonary nodule with peripheral yet distinct calcification in the superior aspect is seen overlying the 5th posterior rib in the right upper lung zone.
The answer is c. Based on the age of the patient, risk factors, and persistent symptoms, further diagnostic tests are warranted. Observation for 11 months is inappropriate. Due to the peripheral nature of this lesion, a CT-guided needle biopsy would be the best diagnostic strategy and have a better yield than a bronchoscopy. Pulmonary function tests would be helpful if surgery is planned, but would not alter the diagnostic steps. In this case, the CT-guided biopsy revealed coccidioidomycosis. This is caused by a fungus (Coccidioides immitis) in the soil and is seen in desert semiarid climates with a short, intense rainy season. It is endemic in southwestern North America, Mexico, and Central and South America. Most patients are asymptomatic or recover fully after initial flulike illness. The radiographic findings of coccidioidomycosis are variable and depend upon the severity of the disease. Most granulomas are smaller than 2 cm, and almost all are less than 3 cm in size. Besides SPNs, in the early stages of coccidioidomycosis patchy infiltrates may be accompanied by hilar and mediastinal adenopathy and less frequently by pleural effusion. In cases of persistent disease, infiltrates may enlarge.

Sunday, 11 November 2012

The photomicrograph is of a urine specimen from a 15-year-old girl.

The photomicrograph is of a urine specimen from a 15-year-old girl. She has had intermittent fever, malaise, and weight loss over the previous several months. Recently she has developed swollen hands, wrists, and ankles, the pain of which seems out of proportion to the clinical findings. She also complains of cold extremities with some ulcerations of her distal digits. The laboratory test most likely to assist in the diagnosis of this condition is

a. Antibodies to nDNA and Sm nuclear antigens
b. Throat culture for group A ß-hemolytic streptococcus
c. Simultaneously acquired urine and serum bicarbonate levels
d. A urine culture
e. Erythrocyte sedimentation rate

The answer is a. The figure accompanying the question depicts a red blood cell cast characteristically found in the urine of patients with glomerular disease. The fever, malaise, and weight loss as well as the arthritis involving mainly small joints are common findings of systemic lupus erythematosus (SLE). Raynaud phenomenon resulting in digital ulceration and gangrene in a few patients may also be seen. Not described in this patient is the oft-seen malar rash in a butterfly distribution across the bridge of the nose and the cheeks. Simultaneous urine and serum electrolytes for bicarbonate determination hint at renal tubular acidosis that often presents with failure to thrive and unexplained acidosis, sometimes with repeated episodes of dehydration and anorexia. Poststreptococcal glomerulonephritis can present with red cell casts, but the symptoms usually develop 8 to 14 days after the acute throat infection. Urinary tract infections, especially of the upper system, can result in casts, but they would be expected to consist of white rather than red cells. Elevation of the erythrocyte sedimentation rate may be found in SLE, but this is a nonspecific finding noted in many other chronic and acute inflammatory conditions; its diagnostic usefulness in this situation is limited.


A 7-year-old child is noted to have 2+ protein on urinalysis.

A 7-year-old child is noted to have 2+ protein on urinalysis. A 24-h collection of urine reveals a protein excretion of 2.5 g/24 h. A thorough history might reveal ingestion of which of the following medications?

a. Tetracycline
b. Streptomycin
c. Trimethadione
d. Diazepam
e. Chlorambucil

The answer is c. The patient described appears to have nephrotic syndrome (protein excretion of greater than 2 g/24 h). Drug-related nephrotic syndrome has been described in connection with the use of trimethadione, penicillamine, captopril, probenicid, ethosuximide, methimazole, lithium, procainamide, chlorpropamide, phenytoin, paramethadione, tolbutamide, some of the nonsteroidal anti-inflammatory drugs (NSAIDs), and certain heavy metals (e.g., gold, mercury-containing medications).


A 3-year-old girl is admitted with the x-ray pictured. The child lives with her parents and a 6-week-old brother.

A 3-year-old girl is admitted with the x-ray pictured. The child lives with her parents and a 6-week-old brother. Her grandfather stayed with the family for 2 months before his return to the West Indies 1 month ago. The grandfather had a 3-month history of weight loss, fever, and hemoptysis. Appropriate management of this problem includes

a. Bronchoscopy and culture of washings for all family members
b. Placement of a Mantoux test on the 6-week-old sibling
c. Isolating the 3-year-old patient for 1 month
d. Treating the 3-year-old patient with isoniazid (INH) and rifampin
e. HIV testing for all family members

The answer is d. The key to controlling tuberculosis in children and eradicating the disease is early detection and appropriate treatment of adult cases; the child, once infected, is at lifelong risk for the development of the disease and for infecting others unless given isoniazid prophylaxis. The usual source of the disease is an infected adult. Household contacts of a person with newly diagnosed active disease have a considerable risk of developing active tuberculosis, and the risk is greatest for infants and children. Therefore, when tuberculosis is diagnosed in a child, the immediate family and close contacts should be tested with tuberculin skin tests and chest radiographs and treated appropriately when indicated. Bronchoscopy would be indicated only in unusual circumstances. Three to eight weeks is required after exposure before hypersensitivity to tuberculin develops. This means that the tuberculin test must be repeated in exposed persons if there is a negative reaction at the time that contact with the source of infection is broken. TB skin tests are usually negative in infants of this age, even when active disease is ongoing. A logical preventive measure is the administration of isoniazid to the baby for 3 months when a Mantoux (purified protein derivative, PPD) can then be placed. Transmission of tuberculosis occurs when bacilli-laden, small-sized droplets are dispersed into the air by the cough or sneeze of an infected adult. Small children with primary pulmonary tuberculosis are not considered infectious to others, and they are not capable of coughing up and producing sputum. Sputum, when produced, is promptly swallowed, and for this reason specimens for microbial confirmation can be obtained by means of gastric lavage from smaller children.


A 13-year-old girl with a history of 2 days of cough and fever has the chest x-ray shown here. The most appropriate treatment is

a. N-acetylcysteine
b. Prolonged course of ampicillin combined with a ß-lactamase inhibitor
c. Lobectomy
d. Postural drainage
e. Thoracentesis and chest tube

The answer is b. The x-ray reveals a lung abscess involving the right upper lobe characterized by the round density, the air-fluid vel, and the opaque rim. Lung abscesses are usually caused by anaerobic bacteria such as bacteroides, fusobacteria, and anaerobic streptococci, and on occasion by Staphylococcus aureus and Klebsiella. The organisms were previously sensitive to penicillin, but some anaerobic organisms (especially bacteroides) are now resistant due to ß-lactam production. Lung abscesses frequently respond surprisingly well to treatment with antibiotics alone.


Wednesday, 7 November 2012

A dental hygienist is concerned about the effects of radiation on the in utero development of her baby. During which of the following periods is the embryo most susceptible to environmental influences that could induce the formation of nonlethal congenital malformations?

a. Fertilization to 1 week of fetal life
b. The second week of fetal life
c. The third through eighth weeks of fetal life
d. The third month of fetal life
e. The third trimester of fetal life

The answer is c. Exposure of the embryo to harmful environmental factors (teratogens), such as chemicals, viruses, and/or radiation, can occur at any time. During the third through eighth weeks of embryonic life, organ systems are developing and are most susceptible to teratogens. During that time, each organ system has its own specific period of peak susceptibility. Exposure of the embryo to teratogens during the first 2 weeks of fetal life (answers a and b) generally induces spontaneous abortion and is, therefore, lethal. After the eighth week of intrauterine development (answers d and e), teratogenic exposure generally results in retardation of organ growth rather than in new structural or functional changes.


Which of the following is in direct contact with maternal blood in lacunae of the placenta?

a. Cells of the cytotrophoblast
b. Extraembryonic mesoderm
c. Fetal blood vessels
d. Cells of the syncytiotrophoblast
e. Amniotic cells

The answer is d. In the developing fetus, the maternal blood is in direct contact with the syncytiotrophoblast. During implantation, the syncytiotrophoblast invades the endometrium and erodes the maternal blood vessels. Maternal blood and nutrient glandular secretions fill the lacunae and bathe the projections of syncytiotrophoblast. Primary villi consist of syncytiotrophoblast with a core of cytotrophoblast cells. In secondary villi, the cytotrophoblast core is invaded by mesoderm and subsequently by umbilical blood vessels in tertiary villi.


Which of the following processes places the developing heart in the presumptive thoracic region cranial to the septum transversum?

a. Gastrulation
b. Lateral folding
c. Cranial folding
d. Neurulation
e. Fusion of the endocardial heart tubes

The answer is c. Cranial folding is responsible for the placement of the developing heart in the presumptive thoracic region of the embryo. Initially, the developing cranial portion of the neural tube lies dorsal and caudal to the oropharyngeal membrane. However, overgrowth of the forebrain causes it to extend past the oropharyngeal membrane and overhang the cardiogenic area. Subsequent growth of the forebrain pushes the developing heart ventrally and caudally to a position in the presumptive thoracic region caudal to the oropharyngeal membrane and cranial to the septum transversum that will form the central tendon of the diaphragm. Gastrulation (answer a) is the process by which epiblast cells migrate to the primitive streak and become internalized to form the mesodermal and endodermal germ layers. Lateral folding (answer b) of the embryo forms the endoderm tube and surrounding concentric layering of mesoderm and ectoderm. Neurulation refers to formation of the neural tube from surface ectoderm (answer d). The fusion of the two endocardial heart tubes (answer e) occurs as lateral folding occurs. The fused tube will form the endocardium surrounded by the primordial myocardium derived from splanchnic mesoderm that will form the heart muscle (myocardium).


Which of the following hematopoietic tissues or organs develops from endoderm?

a. Thymus
b. Tonsils
c. Bone marrow
d. Spleen
e. Blood islands

The answer is a. The thymic parenchyma (epithelial cells) develops from endoderm of the third pharyngeal (branchial) pouches. The thymic rudiment is invaded by bone marrow–derived lymphocyte precursors early in the third month of development. The tonsils (answer b) develop as partially encapsulated lymph nodules. Their parenchymal framework is derived from pharyngeal mesoderm. Bones, of course, whether formed by intramembranous or endochondral ossification, are derived from mesoderm. Their forming marrow cavities are populated by hematopoietic stem cells (answer c) beginning in the second month of fetal life. The connective tissue capsule and skeletal framework of the spleen develop from splanchnic lateral plate mesoderm during the fifth week and are quickly invaded by hematopoietic cells of the myeloid lineage (answer d). It remains an active hematopoietic organ until at least the seventh month in utero. Blood islands develop by differentiation of mesodermal cells in the extraembryonic mesoderm lining the yolk sac during the third week of fetal development (answer e). They give rise to vitelline vessels and are the major site of red blood cell formation in the early embryo.  

Fetal blood from the placenta is about 80% oxygenated. However, mixture with unoxygenated blood at various points reduces the oxygen content. Which of the following fetal vessels contains blood with the highest oxygen content?

a. Abdominal aorta
b. Common carotid arteries
c. Ductus arteriosus
d. Pulmonary artery
e. Pulmonary vein

The answer is b. Blood from the placenta in the umbilical cord is about 80% oxygenated. Mixture with unoxygenated blood from the vitelline veins and the inferior vena cava reduces the oxygen content somewhat. However, this stream with relatively high oxygen content is directed by the valve of the inferior vena cava directly through the foramen ovale into the left atrium. This prevents admixture with oxygen-depleted blood entering the right atrium from the superior vena cava. Thus, the oxygen-saturated blood entering the left ventricle and pumped into the aortic arch, subclavian arteries, and common carotid arteries has the highest oxygen content. The oxygen-depleted blood from the superior vena cava is directed into the right ventricle and then to the pulmonary trunk. Although a small portion of this flow passes through the lungs (where any residual oxygen is extracted by the tissue of the nonrespiring lung), most is shunted into the thoracic aorta via the ductus arteriosus and thereby lowers the oxygen content of that vessel. This occurs distal to the origins of the carotid arteries and ensures that the rapidly developing brain has the best oxygen supply. The pattern of blood supply in the fetus and the changes that occur at birth are shown in the following figures.

Friday, 2 November 2012

In performing a tracheostomy, authorities agree that

Option A. The strap muscles should be divided
Option B. The thyroid isthmus should be preserved
Option C. The trachea should be entered at the second or third cartilaginous ring
Option D. Only horizontal incisions should be used
Option E. Formal tracheostomy is preferable to cricothyroidotomy as an emergency procedure

The correct answer is c. Although tracheostomy is occasionally an emergency procedure, it can be more effectively performed in an operating room where hemostasis and antisepsis are readily achieved. Most authorities recommend a horizontal incision; however, limited direct midline incisions have the advantage of not opening any unnecessary tissue planes and perhaps reducing the incidence of bleeding complications. Both approaches have advocates. In either case, the skin incision is made just below the cricoid cartilage, the strap muscles are spared and retracted, the thyroid isthmus is divided if necessary, and the trachea is entered at the second tracheal ring. The second and third tracheal rings are incised vertically, allowing placement of the tracheostomy tube. The first tracheal ring and the cricoid cartilage must be left intact.


Diagnostic abdominal laparoscopy is contraindicated in which of the following patients?

Option A. A patient with rebound tenderness following a tangential gunshot wound to the abdomen
Option B. A stable patient with a stab wound to the lower chest wall
Option C. A patient with a mass in the head of the pancreas
Option D. A young female with pelvic pain and fever
Option E. An elderly patient in the intensive care unit suspected of having intestinal ischemia

The answer is a. The indications for diagnostic laparoscopic exploration are increasing rapidly as the tools and techniques for such intervention improve. In the stable trauma patient with a tangential gunshot wound or with a stab wound to the lower chest wall or abdomen, laparoscopy may show no actual peritoneal penetration and might make a laparotomy unnecessary. If the peritoneum or diaphragm is injured, subsequent laparotomy and exploration are generally indicated to exclude other possible injuries and to facilitate repair of the diaphragm. All unstable patients or those with signs of peritoneal irritation (e.g., rebound tenderness) should undergo prompt celiotomy Laparoscopic staging of malignancies allows improved preoperative assessment of the resectability of intraabdominal malignancies. The procedure has proved particularly useful in cases with pancreatic carcinoma. Laparoscopic evaluations may expedite differentiation of competing etiologies of right lower quadrant pain; this would allow appendectomy for appendicitis or appropriate therapy such as intravenous antibiotics for pelvic inflammatory disease and preempt celiotomy. In critically ill patients, the development of low flow or embolic ischemic insults to the bowel can be fatal if not recognized and treated early. Many such patients are already being ventilated in intensive care units; in this setting, bedside laparoscopy can ascertain the need for early exploration for bowel revascularization or resection.


The substrate depleted earliest in the postoperative period is:

Option A. Branched-chain amino acids
Option B. Non-branched-chain amino acids
Option C. Ketone
Option D. Glycogen
Option E. Glucose

The correct answer is d. The metabolic response to surgery (and other trauma) is a result of neuroendocrine stimulation that sharply accelerates protein breakdown, stimulates gluconeogenesis, and produces glucose intolerance. The glycogen stores are rapidly depleted because of a fall in insulin and a rise in glucagon levels in the plasma. The peripheral effects of the neuroendocrine secretion result in an increase in plasma levels of amino acids, free fatty acids, lactate, glucose, and glycerol. In the liver, the cortisol and glucagon stimulate glycogenolysis, gluconeogenesis, and increased substrate uptake.

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.