Explanation:

The combination of optochin sensitivity and positive Quellung reaction is characteristic of a single organism, Streptococcus pneumoniae. The other encapsulated organisms that have Quellung-positive reactions are Haemophilus influenzae, Neisseria meningitidis, and Klebsiella pneumoniae. However, none of these organisms are optochin-sensitive. The other choices, Escherichia coli and Neisseria gonorrhoeae, are not encapsulated.

Explanation:

This patient has systemic sclerosis, also called scleroderma. Antibodies to topoisomerase I (anti-Scl-70) occur in up to 70% of patients with diffuse systemic sclerosis, but only rarely in other disorders. Systemic sclerosis, is characterized initially by excessive fibrosis and edema of the skin, especially the hands and fingers, producing sclerodactyly (characteristic changes in the fingers, which resemble claws). Raynaud phenomenon is common. The diffuse type of systemic sclerosis generally spreads to include visceral organs, such as the esophagus (producing dysphagia), the lungs (producing pulmonary fibrosis), the heart (leading to heart failure or arrhythmia), and the kidneys (renal failure causes 50% of scleroderma deaths). Females are affected more than males (3:1 ratio). A more restricted variant of systemic sclerosis, with a somewhat more benign course, is CREST syndrome (Calcinosis, Raynaud syndrome, Esophageal dysmotility, Sclerodactyly, and Telangiectasia), characterized by the presence of anti-centromere antibodies (although 10% of CREST patients will have anti-topoisomerase antibody as well). Anti-ds DNA and anti-Sm (Smith antigen) are characteristic of systemic lupus erythematosus (SLE) but are not common in patients with systemic sclerosis. Rheumatoid factor is an autoantibody directed against IgG. It is found in patients with rheumatoid arthritis. Anti-SS-A is typically seen in Sjögren syndrome (although it may also be seen in SLE).

Explanation:

Explanation:

The symptoms described indicate that John suffers from Duchenne muscular dystrophy (DMD), while Trevor has Becker muscular dystrophy (BMD). Both diseases are caused by mutations in the gene coding for dystrophin, a 427 kDa protein with a flexible rod like structure having globular structures at either end. Its amino terminal end binds to the actin filaments of myofibrils, while the cysteine rich carboxy terminus binds to beta dystroglycan as, well as other elements of the sarcolemmal membrane. Beta dystroglycan, in turn, anchors the entire complex to the basal lamina via laminin. In. short, dystrophin is a molecule that plays a critical role in maintaining muscle fiber integrity; when it is absent or nonfunctional the myofibril literally falls apart. DMD is caused by mutations in the dystrophin gene that significantly disrupt large segments; these mutations often are associated with frame-shift induced deletions, or with other mutations that disrupt critical structural elements, usually in the actin binding head of the molecule. BMD is generally caused by point mutations that permit residual function of the dystrophin molecule. As a result of these mutations, typically less than 5% bf normal dystrophin levels are found in DMD while some. 30-80% is retained in BMD. Options B, C, D, and E are not correct since mutation in genes coding for laminin or emerin do not cause DMD or BMD. However, both of these proteins are essential for the structural and functional integrity of muscle; and there is another form of MD that is associated with their deficiencies. Deficiencies of a form of laminin (laminin NC) cause X linked. Emery Dreifuss Muscular Dystrophy (EDMD) and an emerin deficiency causes the autosomal dominant form of EDMD. The two forms are clinically indistinguishable and are characterized by slowly progressive muscle weakness and wasting starting with a scapulohumeroperoneal distribution, which clearly distinguishes it from either DMD or BMD. Both emerin and laminin NC play a role in stabilizing the inner nuclear membrane and are found in particularly high concentration in skeletal and cardiac muscle. Their similar function probably accounts for the phenotypic similarity of the two forms of this disease. In both forms, the primary cause of morbidity and death is cardiac disease, which may occur anywhere from the teen years to the decade. This is an example of locus heterogeneity) i.e., similar phenotypes caused by mutations at different genetic loci.

Explanation:

Choriocarcinomas are most common in men aged 15-25 years. These tumors are highly malignant and are associated with gynecomastia or testicular enlargement. Laboratory studies typically show elevated serum and urine human chorionic gonadotropin (hCG) levels. Sertoli cell tumors can produce small amounts of androgens or estrogens, but usually not enough to cause endocrinologic changes. They may present with testicular enlargement. Microscopic exam reveals uniform, tall, polyhedral cells with clear cytoplasm, growing in cords resembling spermatic tubules. Teratomas can occur at any age but are most common in infants and children. This type of tumor appears as a testicular mass. Microscopically, it may show differentiation into any of the three germ layers: endoderm, mesoderm, or ectoderm. Yolk sac tumors are most common in infants and children; they are rare in adults. They can also coincide with embryonal carcinomas. Serum AFP is elevated.

Explanation:

This patient is experiencing symptoms of hypocalcemia secondary to diminished parathyroid hormone (PTH) secretion. This must always be considered in a patient who undergoes total or subtotal thyroidectomy, because the parathyroids are nestled in the tissue surrounding the thyroid gland. Surgical attempts to leave portions of the parathyroids intact are sometimes unsuccessful. Other causes of decreased PTH include neck irradiation, autoimmune phenomena (polyglandular autoimmune syndromes), dysembryogenesis (as in DiGeorge syndrome), and heavy metal damage (Wilson disease, hemosiderosis, hemochromatosis). Bone metastases would cause hypercalcemia, as a result of osteolysis. Hashimoto thyroiditis is the most common cause of hypothyroidism and results in decreased thyroid hormone and elevated thyroid-stimulating hormone (TSH) levels. Serum calcium and PTH should be normal. Hypervitaminosis D would cause hypercalcemia. Hypomagnesemia may cause a functional hypoparathyroidism, because magnesium is needed for PTH activity in tissue. In such a case, however, actual PTH levels would not he decreased. Severe hypomagnesemia (levels below 0.4mmol/L [1 mg/dl] blocks release of PTH, but mild hypomagnesemia can actually enhance PTH release.

Explanation:

The only disease listed that has been established as related to an oncogenic virus is adult T cell leukemia. This disease is endemic in Japan. It is caused by the human T cell leukemia virus known as HTLV-1. You should also be aware of the other neoplastic diseases thought to be caused by viruses: Burkitt lymphoma (Epstein-Barr virus), hepatocellular carcinoma (hepatitis B virus), cervical/penile/anal carcinoma (human papillomavirus), and Kaposi sarcoma. Note: Kaposi sarcoma is associated with HIV but is now thought to be caused by a specific Kaposi sarcoma-associated herpesvirus-HHV 8 (human herpesvirus type 8).

Explanation:

Explanation:

Amebiasis, caused by Entameba histolytica, is a parasitic diarrheal infection, which forms teardrop-shaped ulcers in the bowel. The organisms may disseminate and cause liver and brain abscesses. Because cell-mediated immunity is requisite for defense against the organism, steroids exacerbate the disease. Typically, the mode of transmission is via ingestion of cysts in contaminated food and water. It is treated with metronidazole (flagyl).

Explanation:

Although air pollution is associated with a number of pulmonary diseases, it has not been definitively linked to carcinoma of the lung. By far, the majority of lung carcinomas result from cigarette smoking, with a dose dependent relationship between the duration and intensity of smoking and mortality from lung cancer. Passive cigarette smoke exposure is also associated with a one and a half to two fold increase in risk, depending on the duration of exposure. Asbestosis increases the risk of all histologic types of lung cancer. There is a synergistic effect with cigarettes, with the risk being increased fivefold in nonsmokers to 50 to 100 times in smokers. Epidemiologic studies have demonstrated an increased risk of lung cancer in persons with dietary deficiencies of vitamin A and beta carotene. Kindred´s with germ line abnormalities of either the p53 or RB tumor suppressor genes have a higher incidence of lung cancer.

Explanation:

Rubella infects a fetus via uteroplacental transfer. Group B Streptococci, Chlamydia, Gonococci, and Mycoplasma all can infect the infant as it passes through the birth canal.

Explanation:

Porphyria cutanea tarda, a heterogeneous group of disorders of heme biosynthesis, is not a manifestation of diabetes mellitus. All of the other conditions have been described in association with diabetes.

Explanation:

Pleomorphic adenom account for 70% of all salivary gland tumors. They present as a painless precauricular swelling. They are well-encapsulated benign tumors, which are easily excised with surgery. The other choices account for less than 30% of all primary salivary gland tumors.

Explanation:

Macrophages are long lived phagocytic cells important in the inflammatory response. Some of the many secretory products of macrophages include binding proteins such as fibronectin, enzyme inhibitors such as alpha-2 macroglobulins, pyrogens such as interleukin I, and tumor necrosis factor, also known as cachectin. Exotoxin is secreted by bacteria.

Explanation:

The disease described is Goodpasture syndrome, in which autoantibodies to basement membrane proteins cause damage to the lungs and kidneys. Pulmonary hemorrhage (especially in smokers) and rapidly progressive glomerulonephritis are common. The characteristic autoantibody present is directed against type IV collagen, a component of the basement membrane, also found in the lens of the eye. Type X collagen is found in epiphyseal plates. Type I collagen is found in bone skin tendon dentin fascia and late wound repair. Type Ill collagen is found in skin blood vessels uterus, fetal tissue and granulation tissue. Type II collagen is found in cartilage (including hyaline cartilage), the vitreous body of the eye, and the nucleus pulposus of the intervertebral disks.

Explanation:

The treatment described is the method necessary for sterilization using an autoclave. Sterilization is an absolute term, depicting the complete removal or killing of all viable organisms. Endotoxin is a molecule (not an organism) that is extremely heat resistant. It is not destroyed by autoclaving, but is removed from surfaces by extensive scrubbing with detergents. The one exception to the rule that infectious agents are destroyed by autoclaving involves prions, the agents of slow viral diseases. These infectious proteins are extremely resistant to killing; and transmission of prion diseases has been proven using brain electrodes that were technically “sterile”. Bacterial forms containing dipicolinic acid describes bacterial spores. Dipicolinic acid is a unique molecule that protects bacterial spores from dessication and changes in pH. Spores are killed by autoclaving, although they are not always killed by chemical disinfectants. Botulinum toxin is heat sensitive and easily destroyed by boiling, so it would not withstand the temperature and pressure of an autoclave. Mycobacterium tuberculosis, although resistant to most environmental pressures due to its extremely waxy cell coat, would not survive autoclaving. Norwalk virus is a naked capsid virus with a shell that allows it to withstand the acidity of the stomach, but it would not survive autoclaving.

Explanation:

To answer this question you must remember the basic principles of bacterial growth. Rapid exponential growth occurs during Log Phase. This means that generation time = the time it takes for one cell to divide into two. Beta-lactam drugs act by inhibiting cell wall synthesis. In a bacterial culture, cell wall synthesis will occur at a maximal rate during the period of exponential growth, which is shown on the graph by letter C. The lag phase is the initial phase of a bacterial culture during which there is no increase in cell number. Cells in a culture at this stage are activating enzymes necessary for metabolism, but are not undergoing cell wall synthesis. The acceleration phase is the initial phase of bacterial multiplication, when cell division has not yet reached a maximum. Although cell wall synthesis would indeed make such cells sensitive to beta-lactam antibiotics it is not the period of maximum sensitivity. The retardation phase is the phase of the bacterial growth curve when toxic metabolic products begin to accumulate and nutrient levels begin to be insufficient to support continued growth. New cell wall synthesis would begin to fall at this point. The maximum stationary phase is a period of the bacterial growth curve when the number of bacteria dividing in the culture equals the number of cells dying. This would not be a period of intense cell wall synthesis.

Explanation:

This patient has arteriosclerosis, in which atherosclerotic plaques in arteries, which can become calcified, limit the distensibility of vessels. When the distensibility of the arterial system decreases, the peak pressure seen during systole increases disproportionately because the vessels cannot dilate sufficiently in response to the increased amount of blood flow. Note in the figure that the normal pulse pressure is about 40 mm Hg (systolic pressure of 120mm Hg-diastolic pressure of 80mm Hg). The pulse pressure has increased to about 80 mm Hg in the patient with arteriosclerosis (systolic pressure of160mm Hg – diastolic pressure of 80 mm Hg). In aortic stenosis the pulse pressure is greatly diminished because of decreased blood flow through the stenotic valve. The aortic pressure pulse contours usually not affected by mitral regurgitation because this is a problem internal to the heart. In mitral valve stenosis the aortic pressure remains the same, however there is an increase in the atrial pressure due to an obstructive lesion to flow between left atrium and left ventricle in diastole. There is a decreased pulse pressure in this condition. In patent ductus arteriosus, a large portion of the blood pumped by the heart flows through the ductus into the pulmonary artery, which allows the diastolic pressure to fall to very low levels before the next heartbeat.

Explanation:

This is one of three common presentations for cystic fibrosis, which is a common genetic recessive disorder in the Caucasian population. The two other common presentations are meconium ileus in infancy and multiple respiratory tract infections, often in later childhood. Cystic fibrosis was the first genetic disease for which a specific lab test was developed: the sweat chloride test. This test is still used diagnostically in its modern form, in which pilocarpine is used to stimulate sweat secretion. The basic underlying defect in cystic fibrosis is an abnormality of the chloride channel (encoded by the cystic fibrosis transmembrane receptor [CFTR] gene), but both the Na+ and Cl- content of the sweat of affected children is increased compared to normal. The disease is characterized primarily by pulmonary and gastrointestinal involvement. Inability to secrete chloride across the mucosa results in increased absorption of sodium and water leading to thick, inspissated secretions that are prone to superinfection. Repeated superinfection leads to bronchiectasis and parenchymal destruction in the lung and constipation in the GI tract. Pancreatic dysfunction results in decreased secretion of pancreatic enzymes, resulting in steatorrhea and malabsorption. The Na content of CSF, serum, urine, and whole blood is normal in children with cystic fibrosis.

Explanation:

Although many of the events that produce atherosclerotic plaques remain elusive, several steps in the process are known. The first gross findings associated with atherosclerotic plaque formation are fatty streaks. Fatly streaks are found in the vasculature of most people in the second decade of life. The fatty streak is a focal accumulation of serum lipoproteins within the intima of the blood vessel wall. As smooth muscle cells migrate to the lesion they produce a connective tissue matrix that overlies the lipid-laden foam cells. When this fibrous covering dislodges, the thrombogenic contents of the lesion are exposed to the circulation and the ensuing clot then occludes the vessels. Tissue ischemia and infarction then occur. The fibrous lesions that follow the fatty streak seldom produce infarction through direct extension of the lesion ischemia may occur with resulting angina, but because the lesion growth is slow, collateral vessels may grow and thus prevent infarction. The fatly streak precedes fibrous lesions found in coronary artery disease. Lipid-laden macrophages, called foam cells, contribute to the core of atherosclerotic lesions. They do not, however, release their lipids through exocytosis, forming a lipid-based occlusion.

Explanation:

The three major causes of neonatal meningitis are group B streptococci (Streptococcus agalactiae), Escherichia coli, and Listeria monocytogenes. All can be found in the vaginal tract of normal women and may contaminate the infant during passage through the birth canal. They colonize the upper respiratory tract and can cause pneumonia, septicemia, and/or meningitis in the neonate. They are readily distinguished on morphologic grounds; the streptococci are gram-positive cocci in chains, E. coli is a gram-negative rod, and L. monocytogenes is a gram-positive pleomorphic rod. There are other gram positive rods that resemble Listeria (e.g., the diphtheroid bacilli found in the upper respiratory tract and on the skin); hence, a motility test is done to confirm the identification. L. monocytogenes is motile at room temperature but not when grown at 37°C. L. monocytogenes is also associated with drinking unpasteurized milk. Neisseria meningitidis is the most common cause of meningitis in school aged children and young adults. It is a fastidious, nonmotile, gram-negative diplococcus that would be a very rare cause of meningeal disease in very young patients, such as this one. Streptococcus pneumoniae is a gram-positive coccus that grows in pairs and short chains. It is the number one cause of pneumonia, septicemia, and meningitis in the elderly. It would not be a common cause of neonatal meningitis.

Explanation:

Explanation:

The infant is suffering from hereditary spherocytosis, a disease that can result from defective erythrocyte cytoskeletal proteins such as spectrin or ankyrin. Spectrin is a cytoskeletal protein in the erythrocyte that helps to maintain the biconcave shape of the cell. Defective spectrin can lead to a destabilization of this network and a tendency of the affected cells to assume a spherical shape and become osmotically fragile. Such cells often become trapped in the splenic cords, and are subsequently destroyed by phagocytes, leading to hemolytic anemia, jaundice, and splenomegaly. A common complication of this disease is bilirubin gallstones, particularly those with more severe hemolytic disease. Although spherocytosis can lead to hemolysis, the resulting anemia is distinct from aplastic anemia which occurs when the bone marrow stops producing new red blood cells, and would be accompanied by a reduced reticulocyte count. Hemorrhoids are exacerbated in patients with portal hypertension, particularly in patients with hepatic disease such as liver cirrhosis. However the jaundice in this patient results not from liver disease but from biliary obstruction, which causes gallstone formation instead.
Since the disease primarily affects red blood cells white blood cell number and function are unaffected, so immunodeficiency is an unlikely complication. Renal stones may result from some hemolytic diseases though not in hereditary spherocytosis.

Explanation:

A facial or scalp port-wine nevus (a facial angioma, or nevus flammeus) should specifically suggest evaluation for Sturge Weber disease. This disease is one of the slowly progressive neurocutaneous disorders called phacomatoses. Other phacomatoses include neurofibromatosis, Von Hippel-Lindau syndrome, and tuberous sclerosis. Features of Sturge-weber syndrome include the previously mentioned “port-wine stain.” which may overlie meningeal angiomatosis on the surface of the ipsilateral hemisphere. Patients may experience focal or generalized seizures, sometimes with hemiparesis, sensory changes, or hemianopia. Mental retardation is often present. Most cases are actually sporadic rather than genetic in origin. Acoustic neuromas are a feature of neurofibromatosis type II. Cerebellar hemangioblastomas are a feature of Von Hippel-Lindau syndrome. Neurofibromas are a feature of neurofibromatosis type I. Subependymal and cortical tubers are features of tuberous sclerosis.

Explanation:

Surgical hypoparathyroidism is the most common cause of primary hypoparathyroidism. Exploration of the anterior neck during thyroidectomy, parathyroidectomy, or removal of neck lesions can compromise parathyroid gland function. Often, the problem occurs because the blood supply to the parathyroid glands is interrupted during the surgery. The decrease in plasma parathyroid hormone leads to hypocalcemia and hyperphosphatemia. The decreased serum calcium is due to decreased absorption of dietary calcium (because vitamin D activation is decreased) and decreased movement of calcium from bone to extracellular fluid. Low serum calcium can lead to tetany and paresthesias because of destabilization of excitable tissue membranes. Tetany is most often observed when there is a rapid decrease in serum calcium, such as that occurring with surgical hypoparathyroidism. The increased serum phosphate is due to decreased renal excretion. Pseudohypoparathyroidism is a rare genetic defect in which the target tissues are insensitive to parathyroid hormone. Because parathyroid hormone is less effective, serum calcium decreases and serum phosphate increases. Pseudohypoparathyroidism is also accompanied by developmental defects, including mental retardation, short stature, and missing metatarsal and/or metacarpal bones. Pseudopseudohypoparathyrodism is also a rare genetic defect in which the same developmental abnormalities as pseudohypoparathyroidism occur, but there is no abnormality in serum calcium, serum phosphate, or parathyroid hormone. In renal failure, hyperphosphatemia occurs because of decreased renal excretion. This can lead to hypocalcemia as the equilibrium between serum phosphate and serum calcium is pushed toward hydroxyapatite. Furthermore, dietary absorption of calcium is decreased because vitamin D activation is decreased by hyperphosphatemia, even before there is significant decrease in renal 1-alpha-hydroxylase activity. The low serum calcium produces a compensatory increase in parathyroid hormone with subsequent bone demineralization (renal osteodystrophy). With vitamin D deficiency, serum calcium and phosphate are both typically decreased. The calcium is low because of decreased dietary absorption. The phosphate is low (not high) because of decreased dietary absorption, and because the secondary increase in parathyroid hormone secretion (due to the hypocalcemia) increases renal excretion of phosphate.

Explanation:

The low T3 syndrome or “euthyroid sick syndrome” occurs with certain systemic illnesses like pneumonia or septicemia, after major surgery, and with malnutrition or starvation. Whatever the cause, the syndrome is characterized by a decrease, not increase in 5-monodeiodinase activity in peripheral tissues like liver and kidney. As a consequence the conversion of circulating T4 to T3 is impaired and blood levels of T3 decrease. The decrease in serum T3 is thought to be a protective adaptation to decrease catabolic processes during the illness or shortage of energy substrates. Primary hypothyroidism is characterized by decreased serum T4 and increased serum TSH. In the euthyroid sick syndrome, serum T4 and TSH are usually within the normal range. Because the low T3 is probably a protective adaptation, treat merit with thyroxine replacement is of little benefit and may actually be harmful. Once the patient recovers from the illness or malnutrition, serum levels of T3 gradually return to normal on their own. A normal step in the breakdown of reverse T3 also involves the action of 5-monodeiodinase, which converts reverse T3 to 3,3-diiodothyronine, Hence, with the low T3 syndrome, serum concentration of reverse T3 is increased, not decreased due to decreased breakdown.

Explanation:

The patient has the classic signs and symptoms of coarctation of the aorta. More than 95% of coarctation occurs just distal to the left subclavian artery in the region of the ductus arteriosus. The descending thoracic aorta is supplied via reverse collateral flow in the intercostal arteries. These arteries, the major branch of which run in the costal groove on the underside of the rib, expand and cause rib notching. Post ductal coarctation can present early with tachypnea and hypertension. The HTN seen is as a result of decreased blood flow to the kidneys, which in turn will activate the Renin Angiotensin Aldosterone system. Anomalies of the radius are seen in association with various cardiac anomalies; however, this certainly would have presented earlier. Expansion of the marrow space can be seen in a variety of blood cell disorders, including thalassemia. Resorption of the distal clavicles can be seen in hyperparathyroidism. Although renal failure can lead to this and hypertension, there would not be a disparity in the blood pressure in the extremities. Scalloping of the vertebral bodies can be secondary to an aortic aneurism, which would not explain the physical findings.

Explanation:

The patient has Dressler syndrome, which is thought to be an autoimmune phenomenon resulting in fibrinous pericarditis with fever and pleuropericardial chest pain several weeks (usually 3 weeks) after a myocardial infarction. Bacterial, fungal and viral infections can cause pericarditis, but would not be suspected in the setting of myocardial infarction. Chlamydia is not a usual cause of pericarditis.

Explanation:

This patient has panhypopituitarism induced by her brain mass. This condition is associated with decreased serum levels of thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, and growth hormone. The X-ray findings (opaque calcifications) and patient description suggest a craniopharyngioma, the most common pituitary tumor in children. Note that non-secreting chromophobe adenomas may also present with hypopituitarism. Weight gain, sluggishness, and depression are all signs of hypothyroidism, resulting from the decreased TSH levels caused by anterior pituitary hypo-function. Amenorrhea and galactorrhea are associated with hyperpituitarism, which is most often associated with a pituitary adenoma that secretes prolactin, growth hormone, or ACTH. Bilateral exophthalmos and palpitations are symptoms of Graves disease. This condition is associated with a decrease in TSH, which occurs in response to elevated thyroid hormone levels; it is not a result of anterior pituitary hypofunction. Coarse facial features and enlarged hands and feet are signs of acromegaly, which may result from increased growth hormone levels associated with hyperpituitarism. Polydipsia, polyuria, and low urine osmolality are symptoms of diabetes insipidus. Central diabetes insipidus is associated with disorders of the posterior pituitary or the hypothalamus (decreased antidiuretic hormone [ADH]). Remember that nephrogenic diabetes insipidus stems from renal unresponsiveness to ADH, not from diminished levels of the hormone.

Explanation:

The child has a rhabdomyosarcoma, which is the most common form of malignant soft-tissue tumor seen in infants and children. The characteristic strap and tadpole cells are immature forms of rhabdomyoblasts (and may be hard to find among many poorly differentiated cells). This child probably has embryonal rhabdomyosarcoma, which can also be seen in the genital urinary tract (where it may form “bunches of grapes”). Despite the prevalence in textbooks of dramatic photographs of genitourinary rhabdomyosarcomas in young children, these tumors actually occur more frequently in the head and neck region, particularly the orbit, nasopharynx, and middle ear. The presence of abnormal mitotic figures dudes the possibility of a benign tumor. Leiomyosarcoma and malignant fibrous histiocytoma are both malignant tumors, but would not be expected to contain strap and tadpole cells.

Explanation:

Anaplastic thyroid cancer carries a very poor prognosis with the vast majority (~90%) having local invasion (cervical lymph glands) and local infiltration, (particularly the trachea) at diagnosis. Lung and bone metastases are common at presentation ~ 50%. Upper airways obstruction frequently requires tracheostomy.

Explanation:

Children are rarely chronic carriers of the organism although for some unknown reason females are more commonly long-term carriers than males (remember Typhoid Mary).
C. Only 50% of cases.
E. Higher threshold but same disease.

Explanation:

This patient has developed nephrotic syndrome, and appears to have a thromboembolic event. The suggestion is that she has had nephritic syndrome before developing the thromboembolism. Deranged coagulation associated with Nephrotic syndrome is a consequence of AT III deficiency, increased fibrinogen and increased Factor VIIIc.

Explanation:

In acute lymphoblastic leukaemia:
Good prognostic factors:

• FAB L1 type
• Common ALL
• Pre-B phenotype
• Low initial WBC

Poor prognostic factors:

• FAB L3 type
• B, T cell type
• Philadelphia translocation, t (9;22)
• Increasing age at diagnosis
• Male sex
• CNS involvement
• High initial WBC (for example, more than 100).

Explanation:

Chronic rejection is characterised by fibrosis of normal organ structures. The pathogenesis of chronic rejection is not clear -some prefer the term “chronic allograft dysfunction” since both immunological (anti dependent and antigen-independent) and non-immunological factors ha been identified. Cell-mediated and humoral immune mechanisms have been implicated in this form of graft rejection.
It has also been suggested that rejection is a response to chronic ischaemia caused by injury to endothelial cells.
Proliferation of intimal smooth muscle is observed leading to vascular occlusion. The fact that chronic rejection is rare in transplants between human leukocyte antigen (HLA)-identical siblings suggests that HLA-antigen dependent immunological factors are important.
Risk factors include:

• Number of previous acute rejection episodes
• Presence of anti-HLA antibodies
• Anti-endothelial antibodies
• Cytomegalovirus (CMV) infection
• Dyslipidaemia
• Hypertension
• Functional mass of the donor kidney and
• Delayed graft function (a clinical manifestation of ischaemia/reperfusion injury).

Explanation:

Whooping cough (pertussis) is caused by the bacterium Bordetella pertussis. B. pertussis is a very small gram-negative aerobic coccobacillus that appears singly or in pairs. Infection is characterised by paroxysms of coughing. Lymphocytosis is typically found. Hemiplegia is a recognised effect of severe whooping cough. The pertussis vaccine is estimated to be 63% to 94% effective in the diphtheria-pertussis-tetanus (DPT) shot.

Explanation:

Fragile X Syndrome is also known as Martin-Bell syndrome. In addition to moderate to severe mental retardation, other characteristics of individuals with Fragile X syndrome may include:

• Large ears
• Macroorchidism
• Prognathism
• Speech delays
• Prominent forehead
• Double-jointedness
• Autistic symptoms and
• Occasional self-mutilation
• The face is typically long and narrow, with a high arched palate and large ears
• Otitis media, strabismus, and dental problems may be present
  Other common characteristics include:
• Hyperextensible joints
• Hypotonia and
• Heart problems including mitral valve prolapse
  In males, abnormally large testes are a distinctive feature.
• In young children:
• Delayed motor development
• Hyperactivity
• Behavioral problems
• Toe walking, and
• Occasional seizures can occur

Explanation:

Explanation:

The highest malignancy rate is associated with a villous growth pattern. Adenomas are rare in countries with a low incidence of cancer. Adenomas and adenocarcinomas are located in the same anatomic location in the colon. In persons with adenomas, immature cells are found higher up the colonic crypt than normal. Although less than 5% of adenomas develop into carcinomas, the frequency of cancer in the polyp increases from 3% in lesions less than one centimeter in size to more than 40% in polyps larger than two centimeters.

Explanation:

As currently understood, a series of genetic changes occur in concert to initially produce an adenoma that may subsequently progress to a carcinoma. The initial step probably involves a mutation of the K-ras proto-oncogene. The gene for familial adenomatous polyposis has been mapped to chromosome 5. Chromosome 17(p53 gene) and chromosome 18 (DDC gene) deletions are thought to be important in malignant transformation. Overexpression of the c-myc gene has been reported in colon cancers.

Explanation:

Explanation:

Congenital hyposplenism occurs in Fanconi´s syndrome. Splenomegaly may result from infiltration of the organ by neoplastic cells or by lipid laden macrophages, as occurs in lymphoma, leukemias, or metastatic tumors. Splenic intrasinusoidal extramedullary hematopoiesis involving all three myeloid cell lines associated with dilated and distended pulp sinuses occurs in myelosclerosis with myeloid metaplasia. Infiltrative diseases, such as Gaucher´s or Niemann Pick disease, produce splenic enlargement by increasing the number of splenic red pulp histiocytes. In hemolytic diseases, such as hereditary spherocytosis, there is pooling of abnormal red blood cells in sinuses and pulp cords because of increased red cell rigidity. Such cells have decreased ability to traverse the red pulp sinusoidal endothelium

Explanation:

Enterotoxigenic E. coli (ETEC), an important cause of traveler´s diarrhea, produces a toxin that activates intestinal adenylate or guanylate cyclase. Consequently the intestinal mucosa overproduces cAMP, resulting in a mild and self-limited secretory diarrhea. Enteroaggregative E. coli (EAEC) does not express a toxin, but is seen to cluster over the colonic mucosa in some individuals. Although occasionally found in patients with chronic diarrhea, no clear mechanism for mucosal pathophysiology has been determined for EAEC. Enterohemorrhagic E. coli (EHEC) classically associated with strain O157:H7 and present in undercooked hamburgers, expresses a Shiga like toxin that causes bloody diarrhea and hemolytic-uremic syndrome. This toxin works by inhibiting the 60S ribosomal subunit. Enteroinvasive E. coli (EIEC) does not express a toxin, but rather is pathogenic through its capacity to invade the colonic mucosa and evoke an inflammatory response. The resulting dysentery like inflammatory diarrhea generally necessitates vigilant hydration but no antibiotics are indicated.
Enteropathogenic E. coli (EPEC) does not produce any known toxins but adheres tightly to the glycocalyx of the colonic mucosa and disrupts the microvilli. Villous atrophy mucosal thinning and inflammation in the lamina propria , are produced resulting in impaired absorption and diarrhea.

Explanation:

After an initial attack of rheumatic fever, an affected individual is at increased risk for developing recurrent rheumatic disease after each pharyngeal infection by beta hemolytic streptococci. Any one of the manifestations of rheumatic disease can reoccur, but will usually resolve. In marked contrast, the damage to the heart valves caused by rheumatic fever can lead to fibrous scarring and deformity, producing valvular dysfunction (particularly mitral stenosis),which may lead to heart failure in late adulthood. This is a great example of a type II hypersensitivity reaction in which tissue-specific autoantibodies cause disease where the antigens are present. The inflammatory response is usually localized rather than systemically. The arthritis produced by rheumatic fever is transitory and resolves after the attack has run its course. There are no long-term complications of the arthritis. Fibrinous pericarditis, like almost any fibrinous inflammatory response, is an acute process. Although the patient may develop some scarring of the pericardium, this is generally not sufficient to produce long-lasting consequences. Myocardial involvement by rheumatic fever is typically seen as Aschoff bodies, collections of fibrinoid necrosis, lymphocytes, plasma cells, and histiocytes within the myocardium. When the event resolves, the Aschoff bodies will be replaced by discrete fibrous scars. No appreciable myocardial dysfunction ensues. Sydenham chorea, the neurologic manifestation of rheumatic fever, leaves no lasting neurologic effects.

Explanation:

Individuals with C3 deficiency have an increased susceptibility to immune complex diseases, of which type III hypersensitivity reaction is an example of. The most important functions of C3 are to remove immune complexes from the bloodstream and enhancing opsonization. Type III hypersensitivity reaction causes immune complexes to self or foreign antigens bound to an antibody; this will activate complement, leading to tissue damage. Examples of type III hypersensitivity reactions include rheumatoid arthritis, SLE, post- Streptococcus glomerulonephritis. Contact dermatitis is a type IV hypersensitivity disease that depends on the action of TH1 cells, macrophages, and cytotoxic T lymphocytes. It does not depend on the presence of antibody and complement. Human immunodeficiency virus-1, which is the cause of acquired immunodeficiency syndrome (AIDS), is an intracellular pathogen that depends on the activation of TH1 cells and their cytokines for a protective immune response. A patient with C3 deficiency would not be expected to be any more susceptible to an intracellular pathogen, such- as this one, than the population at large would be. Measles is caused by rubeola virus, which is an intracellular pathogen and would not be affected by deficiencies in complement. Mycobacterium avium-intracellulare is an intracellular bacterium that infects phagocytic cells. It is controlled by a cell-mediated response, not a complement-mediated response.

Explanation:

Explanation:

Kartagener syndrome, an autosomal recessive disorder characterized by bronchiectasis, sinusitis, and situs inversus, is classified as an “immotile cilia syndrome” It is associated with the absence of inner or outer dynein arms in the cilia. This leads to abnormal ciliary mobility of the sperm, producing infertility. Ciliary abnormalities in the respiratory tract lead to sinusitis and bronchiectasis. Sphingomyelinase deficiency occurs in Niemann-Pick disease (autosomal recessive transmission). Sphingomyelin accumulates in the phagocytes. “Foamy histiocytes” appear in the liver, spleen, lymph nodes, and skin. Clinical manifestations include hepatosplenomegaly and, in some cases, neurologic deterioration. Patients usually do not survive beyond 3 years of age.
Fibrillin deficiency occurs in Marfan syndrome (autosomal dominant). Patients are characteristically tall and thin, and their fingers are spider-like (arachnodactyly). Anatomic abnormalities include ectopia lentis (displaced lens of the eye) and aortic dilatation predisposing to aortic aneurysm. 47,XXY karyotype, also known as Klinefelter syndrome, is characterized by male hypogonadism. It can cause male infertility, but nothing else in the question suggests this is the case. One would expect to see atrophic testes, tall stature, and gynecomastia. Mental retardation is sometimes present. Hexosaminidase A deficiency causes Tay-Sachs disease (autosomal recessive), which occurs most commonly in Ashkenazi Jews. The disease causes CNS degeneration and blindness, and patients exhibit motor and mental deterioration (e.g., loss of developmental milestones). A classic clue is a macular “cherry-red spot” on ophthalmoscopic examination. Patients usually do not survive beyond 3 years of age.

Explanation:

When you see Chlamydia psittaci, one word should come to mind-birds! Infection with this organism is an occupational hazard for anyone who works with birds (e.g., veterinarians, pet store employees), including poultry farmers. Individuals who work with cats would be at an increased risk for infection with Pasteurella multocida (which is acquired primarily through cat bites), Bartonella henselae (cat scratch fever), and the protozoan Toxoplasma gondii (which can be acquired from ingestion of food contaminated with cat feces). Florists are at increased risk for infection with the fungus Sporothrix schenckii, a primary pathogenic fungus acquired by inoculation (e.g., a rose thorn puncturing the skin). A person who works at a homeless shelter would be at increased risk for infection with Mycobacterium tuberculosis, since this organism is spread through the air and is prevalent in the homeless community. Slaughterhouse workers are at an increased risk for infection with Brucella, a bacterium that is acquired by handling infected animals.

Explanation:

Humans become infected with Toxoplasma gondii by ingesting cysts in contaminated food or through contact with cat feces. The veterinarian in question was therefore particularly at risk of infection. T. gondii is especially hazardous in pregnant women because the organism can be transmitted to the fetus through the placenta. (It is part of the ToRCHeS group of congenital infections-Toxoplasma, Rubella, CMV, Herpes/HIV, and Syphilis). Since infected mothers are usually asymptomatic, cases often go unnoticed. Occasionally, patients present with cervical lymphadenopathy, as did the veterinarian, and require treatment to prevent complications in the fetus. Though newborns are also often asymptomatic, they are at risk for developing the classic triad of chorioretinitis (at birth or later in life), hydrocephalus, and cerebral calcifications. Note that T. gondii is also a common cause of CNS infections (e.g., encephalitis) in HIV positive patients. Isospora belli is an intestinal protozoan that causes watery diarrhea, particularly in immunocompromised patients. Fecal-oral transmission of oocysts allows invasion of small intestinal mucosa, destroying the brush border. Leishmania donovani causes kala azar (visceral leishmaniasis), which is characterized by fever, weakness, weight loss, splenomegaly, and skin hyper-pigmentation. It is prevalent in regions of the Mediterranean, Middle East, Russia, and China. The vector is the sandfly. Plasmodium vivax causes malaria and is transmitted by the female Anopheles mosquito, which introduces sporozoites into the blood. These differentiate into merozoites that destroy erythrocytes. Splenomegaly ensues. Other species of this organism that cause malaria are P. malariae, P. ovale and P. falciparum (which causes a more severe form of the disease). Note that sickle cell trait confers resistance to P. falciparum.
Trypanosoma cruzi causes Chagas disease, characterized by unilateral facial edema and nodules, fever, lymphadenopathy, and hepatosplenomegaly. It affects cardiac muscle most severely and is a major cause of cardiac disease worldwide. The reduviid (“kissing”) bug is the vector that infects humans by defecating in the bite wound.

Explanation:

This simple mathematical problem asks if the student understands the life cycle of the malaria parasite, specifically Plasmodium vivax. To answer the question, the student needs to understand the terminology and sequence of steps that this agent of “benign tertian” malaria goes through in the human host. The infectious form inoculated by the vector mosquito is the sporozoite. It immediately seeks out a hepatocyte, penetrates it, and undergoes the process of schizogony (asexual fission). The question stem tells us that one sporozoite is injected and within 10 days, 100 daughter merozoites will be produced from each sporozoite. Thus, at 10 days, 100 exoerythroeytic merozoites will be released. These parasitic forms will now seek out erythrocytes, and at 2 day intervals (for P. vivax and P. ovule) will again undergo schizogony; this time, the question tells us to produce 10 merozoites per erythrocyte. There is no repetition of schizogony in the liver, but the cycle is repetitive in the erythrocytes, so that each crop of merozoites will repenetrate erythrocytes and undergo schizogony at 2 day intervals until the immune response or drug treatment stop the cycle. Thus, every 2 days after leaving the liver, there will be ten times the number of merozoites released as were released in the last cycle. The number of merozoites at 22 days will be 100 (day 10) x 10 (day 12) x 10 (day 14) x 10 (day 16) x 10 (day 18) x 10 (day 20) x 10 (day 22), or 100 x 10⁶ or 1 x 10⁸. If this question were posed for P. malariae, the erythrocytic schizogonic cycles would our at 3 day intervals, and if the question were posed for P falciparum, it would not be answerable because asynchronous schizogony and multiple infections of individual erythrocytes can alter the speed of multiplication.

Explanation:

The question stem describes Wernicke, or receptive, aphasia. It is caused by a lesion in Wernicke´s area, which is located in the posterior part of the superior temporal gyms of the language dominant hemisphere.
Broca (expressive) aphasia is a disorder primarily of language output. Speech is slow and effortful, phrase length is short, and the patient tends to use only common nouns, verbs, and, occasionally, adjectives. Comprehension is relatively intact. Repetition is generally disturbed comparable to the amount of spontaneous output. It is produced by a lesion of Broca´s area, which is in the posterior part of the inferior frontal gyrus of the language dominant hemisphere. Conduction aphasia is produced by a lesion in the arcuate fasciculus, which is in the posterior inferior part of the parietal lobe of the language dominant hemisphere. This effectively disconnects Broca´s area from Wernicke´s area, resulting in the inability to repeat. Global aphasia occurs with the destruction of Broca´s area, Wernicke´s area, and the arcuate fasciculus, resulting in a combination of both Broca and Wernicke aphasias. Mixed transcortical aphasia results from damage to much of both Broca´s and Wernicke´s areas, but leaves the arcuate fasciculus intact. The patient has little spontaneous language output or comprehension but is still able to repeat.

Explanation:

Bronchogenic adenocarcinoma is only weakly associated with smoking. This disorder is the most common lung cancer seen in nonsmokers and in women. Bronchioloalveolar carcinoma is a relatively uncommon form of carcinoma of the lung. It arises in the lung periphery and does not appear to be clearly related to smoking. Large cell (anaplastic) carcinomas are unusual and probably represent undifferentiated variants of squamous cell and bronchogenic adenocarcinomas. Small cell (oat cell) carcinoma is very strongly associated with smoking. Squamous cell carcinoma is very strongly associated with smoking.

Explanation:

The earliest microscopic signs of a myocardial infarct are intercellular edema and “wavy change” at the periphery of the affected area. The wavy change in the myocytes is thought to be due to the effects of nearby, intact myocyte contraction on the ischemic myocytes situated at the periphery of the lesion. Such changes can be observed as early as 1 hour after infarction. Neutrophilic infiltration is observed within about 12 hours of infarction. Necrosis with preservation of cell outlines is a definition of coagulative necrosis, the type that characterizes the myocardium. Coagulative necrosis appears within the first days after an infarct but is not evident during the first hour or so, when wavy change is apparent. Proliferation of fibroblasts is a component of scar formation, which occurs weeks after an infarct (if the patient survives). A softened, yellow plaque is generally visible about 1 week after infarction.

Explanation:

Mild renal failure is a common cause of hyperkalemia (excess serum potassium). The mechanism appears to be deficient renin production by the damaged kidney which in turn causes lower than normal secretion of aldosterone by the adrenal cortex. The relative lack of aldosterone causes hyperkalemia because there is less than normal exchange of Na for of by the renal tubules (Na+ is comparatively lost while K+ is comparatively saved). Treatment can be either with a mineralocorticoid, such as hydrocortisone, or more easily with a potassium-wasting diuretic such as furosemide. The combination of high renin and high aldosterone can be seen in secondary hyperaldosteronism due to processes such as renal ischemia, renal juxtaglomerular cell, hyperplasia, and edema. Clinically secondary hyperaldosteronism produces sodium retention and potassium wasting. The combination of high renin and low aldosterone can be seen in nonrenal causes of hypoaldosteronism, such as with biosynthetic defects or following surgical ablation of the adrenal glands. The combination of low renin and high aldosterone can be seen in primary hyperaldosteronism (Conn syndrome) and produces sodium retention and potassium wasting. Hyperkalemia with normal renin and normal aldosterone levels can be seen when potassium-sparing diuretics are coupled with high dietary intakes and as a drug side effect (e.g.ACE inhibitors).

Explanation:

The patient probably has celiac sprue, which is caused by an allergic, immunologic, or toxic reaction to the gliadin component of gluten (from wheat). The symptoms and pathologic changes usually reverse with complete removal of gliadin from the diet. Therapeutic failures are frequently due to hidden wheat in the diet. Patients with celiac disease have an increased risk of developing gastrointestinal lymphoma. Oftentimes patients will have anti gliadin antibodies. Most cases of gastric peptic ulcer disease can now be attributed to H. pylori infections. Because the gastric biopsy was negative and blunting of the villi is not seen in these infections, this is an incorrect answer. Anti-mitochondrial antibodies are found in the majority of patients with primary, biliary cirrhosis. Anti smooth muscle antibodies are seen in autoimmune hepatitis. Although lactose intolerance can be seen in celiac sprue from decreased lactase production it is not the primary problem

Explanation:

Hip fracture and prolonged bed rest are classic risk factors for the development of pulmonary thromboemboli (PE). Common clinical manifestations of PE are hypoxia (due to ventilation/perfusion mismatch) despite a normal chest X-ray, tachycardia, and delirium in older patients. Cerebral hemorrhage might cause delirium but would not directly cause hypoxia unless the patient was hypoventilating (e.g. because of brainstem involvement). Cerebral infarction could produce delirium but would not directly cause hypoxia unless the patient was hypoventilating.
Myocardial infarction could account for delirium and tachycardia, but not for hypoxia with a normal chest X-ray. Severe congestive heart failure after myocardial infarction could cause hypoxia due to pulmonary edema, but the chest X-ray would not be normal. A pulmonary infection may cause delirium, tachycardia, and hypoxia, but the onset of symptoms would likely be slower, the chest x-ray would be abnormal, and the patient would be likely to have a higher fever.

Explanation:

The condition described is acanthosis nigricans. Mild forms are common and may be associated with obesity and endocrine abnormalities. More extensive forms, such as in this patient, may be associated with malignant disease: usually an adenocarcinoma (often lung), less commonly a lymphoma. The pattern is important to recognize because the eruption may precede other symptoms of the malignancy by several years.

Explanation:

This is a question that tests your ability to distinguish between ulcerative colitis (UC) and Crohn disease. First, you need to figure out which one this patient has. The key clues here are the bloody diarrhea (much more common in UC), the rectal involvement, and, especially, the continuous nature of the mucosal damage. Once you´ve figured out that the patient has UC, you need to identify the answer choice that is characteristic of UC. The correct answer is pseudopolyps, which are inflammatory polyps found in ulcerative colitis and not Crohn disease. All the other choices are features of Crohn disease. Especially diagnostic is the transmural nature of the inflammation, which can lead to the development of fissures and fistulas. Remember also that although Crohn disease can involve any part of the gastrointestinal tract, it typically does not involve the rectum and is usually found in the terminal ileum anther colon. In contrast to UC, the lesions are discontinuous (skip lesions).

Explanation:

It is important to remember that not all oliguria is caused by intrinsic renal disease. Shock, of any etiology, is an example of a prerenal cause of oliguria in which poor renal perfusion leads to inadequate urine output. Other examples of prerenal causes include hepatorenal syndrome, postoperative oliguria, and dehydration. Postrenal causes of oliguria usually involve bilateral obstruction and may be due to disease of the ureters, bladder neck, or urethra. Acute glomerulonephritis and transplant rejection are examples of renal causes of oliguria. Bladder tumor and prostatic hyperplasia are examples of postrenal causes of oliguria.

Explanation:

Osteoporosis in a young male would be unusual. Any symptoms or features of hypogonadism or hypercalcaemia should be elicited. Hyperprolactinaemia cause hypogonadism would need to be present for a considerable amount of time before producing osteoporosis. Prostate malignancy does not cause osteoporosis

Explanation:

Shigellosis is a possible cause of profuse bloody diarrhoea as cholera and giardiasis are associated with watery diarrhoea. Trophozoites are seen in acute amoebic dysentry, and the test is not 100% sensitive.

Explanation:

Causes of acute renal failure can be divided into pre-renal, renal a post-renal.

• Pre-renal:
• Hypovolaemia (gastroenteritis, burns, sepsis, haemorrhage, nephrotic syndrome)
• Circulatory failure
• Renal:
• Vascular: HUS, vasculitis, embolus, renal vein thrombosis
• Tubular: acute tubular necrosis, ischaemic, toxic, obstructive
• Glomerular: glomerulonephritis
• Interstitial: interstitial nephritis, pyelonephritis
• Acute chronic renal failure.
• Post-renal:
• Obstruction, either congenital or acquired.

Although Alport´s syndrome is associated with end stage renal failure this usually progresses gradually so that it occurs in adult life.

Explanation:

IgA nephropathy (Berger´s disease) is the most common glomerulonephritis worldwide, and characteristically affects young males, presenting with frank haematuria after an episode of pharyngitis. However it may also present with proteinuria, microscopic haematuria, renal failure or hypertension. It is probably part of a Spectrum of disease with Henoch Schoenlein Purpura, which presents with arthritis, rash, abdominal pain and nephritis. In both there are mesangial IgA deposits in the kidney.

Explanation:

Explanation:

Stiffness and weakness is more typical of polymyositis. This would suggest polymyostis. This is typical. It occurs later in life

Explanation:

Explanation:

Pseudomyxoma peritonei is a disease caused by a mucinous cystadenocarcinoma of the ovary. It is characterized by abdominal distension and pain, and occurs because the tumor cells secrete a large amount of mucus. The other diseases listed do not cause this condition.

Explanation:

Interstitial nephritis can cause diabetic nephropathy but is much less common than diffuse glomerulosclerosis. IgA deposition and glomerulonephritis are unusual in diabetes. Nephrolithiasis may be associated with diabetic nephropathy but is much less common than.

Explanation:

A child born with PKU usually appears normal at birth.

Explanation:

The 27 nm virus is spread predominantly via the fecal oral route. Transfer of the virus between fingertips and the environment has been documented. Fecal shedding of the virus occurs during the final week of the incubation period and during the prodromal period, declining at the time of peak transaminase elevations. Neither a chronic carrier state nor a chronic form of the disease exists. The presence of IgM antibodies usually indicates infection within the past few months. IgG antibodies, on the other hand, persist for many years.

Explanation:

The fasting serum gastrin is normal in patients with duodenal ulcer (DU); however, the gastrin response to a meal is increased. The increase in serum gastrin following a meal occurs, in part, because acid suppresses gastrin release less effectively in DU patients compared with controls.
DU patients have an increase in parietal cell mass, which may be caused by the trophic (growth promoting) effects of gastrin. Patients with DU have an increased basal acid output that totally disappears following eradication of the H. pylori infection. However, the increase in maximal acid output, which occurs in response to IV gastrin, can remain following eradication of the H. pylori infection and is likely to result from the increased parietal cell mass. The secretion of pepsin is usually doubled in DU patients.

Explanation:

Explanation:

Anosmia is not associated with osteogenesis imperfecta, while osteopenia, blue sclerae, collagen mutations, and multiple fractures are all manifestations of osteogenisis imperfect.

Explanation:

Bullous eruptions of the skin occur with impetigo, pemphigus, pemphigoid, and toxic epidermal necrolysis. Secondary syphilis often produces morbilliform lesions of the skin, not bullous lesions.

Explanation:

Hydrocarbonaspiration causes pneumonitis, especially in children. Lipids, such as mineral oil, produce a chronic inflammatory response, especially following chronic aspiration. Aspiration of inert materials, such as water produces injury through asphyxiation. Small food particles, in the absence of gastric acid, can produce fibrotic, granulomatous pulmonary lesions. Larger food particles may cause death by asphyxiation. Surfactant creates a uniformly distributed phospholipid monolayer over the aqueous subphase, lining the alveolar surface, thereby decreasing the surface tension.

Explanation:

Accumulation of unconjugated bilirubin in the basal ganglia is responsible for this syndrome of bilirubin encephalopathy. Iron, conjugated bilirubin, biliverdin, and galactosamine are not involved in kernicterus.

Explanation:

Explanation:

The coxsackieviruses (as well as poliovirus, echoviruses, and rhinoviruses) are picornaviruses that are composed of single stranded linear, positive-sense RNA. The virus particles are non-enveloped, 27 nm icosahedrons with 60 subunits that replicate in the cytoplasm. Pox viruses, herpes viruses and adenoviruses have double stranded DNA Reoviruses have double stranded RNA. Parvoviruses have single-stranded DNA. Orthomyxoviruses have single stranded negative sense RNA.

Explanation:

The organism described is Staphylococcus aureus, which is a common colonizer of the nasopharynx, where it may be part of the normal flora. At other sites, it is much more likely to be a true pathogen. Clues that an organism is a colonist in a particular setting include the presence of many other organisms in significant numbers, and relatively small numbers of acute inflammatory cells in smears made from the patient´s material. Blood and urine are normally sterile, and the isolation of S. aureus from these sites would probably indicate true infection. Stool contains large numbers of bacteria, but Enterococcus would be much more likely to be present as part of the normal flora than S. aureus. The vagina usually has a mixed flora, but S. aureus is not a normal colonist at this site.

Explanation:

Enterotoxigenic E. coli (ETEC), an important cause of traveler´s diarrhea, produces a toxin that activates intestinal adenylate or guanylate cyclase. Consequently the intestinal mucosa overproduces cAMP, resulting in a mild and self-limited secretory diarrhea. Enteroaggregative E. coli (EAEC) does not express a toxin, but is seen to cluster over the colonic mucosa in some individuals. Although occasionally found in patients with chronic diarrhea, no clear mechanism for mucosal pathophysiology has been determined for EAEC. Enterohemorrhagic E. coli (EHEC) classically associated with strain O157:H7 and present in undercooked hamburgers, expresses a Shiga like toxin that causes bloody diarrhea and hemolytic-uremic syndrome. This toxin works by inhibiting the 60S ribosomal subunit. Enteroinvasive E. coli (EIEC) does not express a toxin, but rather is pathogenic through its capacity to invade the colonic mucosa and evoke an inflammatory response. The resulting dysentery like inflammatory diarrhea generally necessitates vigilant hydration but no antibiotics are indicated.
Enteropathogenic E. coli (EPEC) does not produce any known toxins but adheres tightly to the glycocalyx of the colonic mucosa and disrupts the microvilli. Villous atrophy mucosal thinning and inflammation in the lamina propria , are produced resulting in impaired absorption and diarrhea.

Explanation:

The description is typical for basal cell carcinoma of the most common form, noduloulcerative, which begins as a pearly papule and progresses to a larger lesion with rolled edges and central ulceration. Histologically, the tumor is composed of small, malignant basal cells that form dermal nests and strands with peripheral nuclear palisading. These skin cancers typically occur on sun exposed areas of the head, neck, and upper trunk. Basal cell carcinoma only rarely metastasizes but can become locally mutilating if neglected. When the carcinoma is located on the face, it may be difficult to adequately excise without damaging facial structures; and at this site, it may occasionally lead to the patient´s death due to the inability to adequately remove the tumor. Benign basaloid cells can be seen in seborrheic keratoses, which classically appear as dark colored, raised lesions that look” stuck onto” the face. Benign melanocytes can be seen in nevi, which classically produce dark macules and papules. Benign keratinocytes can be seen in acanthomas, which have a variety of appearances depending upon the specific type. Malignant melanocytes can be seen in melanomas, which classically appear as dark colored nevi with variable coloration and poorly demarcated edges.

Explanation:

This patient most likely suffered a stroke caused by the formation of a thrombus (secondary to atrial fibrillation) that lodged in the middle cerebral artery (MCA) territory, which supplies the lateral surface of the frontal, parietal, and upper temporal lobes; the internal capsule; and most of the basal ganglia. Occlusion of the MCA results in (1) anesthesia of the contralateral face and upper limb, and (2) spastic paresis of the contralateral lower face and upper limb (the upper face is spared because of the concomitant innervation of the ipsilateral cranial nerve VII). Broca aphasia will result when branches of the left MCA, which supply the inferior frontal gyrus, are affected. Recall that the language dominant hemisphere is usually on the left. The aphasia is characterized by slow, nonfluent speech with deficits in word-finding (“broken” aphasia). Because comprehension is normal (patients are able to follow commands), they are typically aware of the problem and appear frustrated. The anterior cerebral arteries (ACA) supply the medial surface of the frontal and parietal lobes, which include motor and sensory cortical areas of the pelvis and lower limbs. ACA occlusion results in spastic paresis and anesthesia of the contralateral lower limb. Urinary incontinence may be present (usually occurs with bilateral damage). The posterior cerebral artery supplies the occipital lobe, the thalamus, and part of the temporal lobe. Occlusion of this artery results in a homonymous hemianopia of the contralateral visual field with macular sparing. The posterior inferior cerebellar artery (PICA) supplies the lateral medulla. Its occlusion leads to a condition known as Wallenberg syndrome (lateral medullary syndrome). These patients present with ipsilateral limb ataxia, ipsilateral loss of pain and temperature sensation of the face, contralateral loss of pain and temperature sensation of the body, ipsilateral Horner syndrome (ptosis, miosis, anhidrosis), hoarseness, dysphagia, nausea/vomiting, vertigo, and nystagmus. The majority of individuals are left hemisphere dominant, and as with this patient, it certainly can be confirmed when the person is right-handed, (Note that even left-handed individuals are generally left hemisphere-dominant).

Explanation:

The precipitation lines joined between Wells 1 and 2 are called a chevron, which is formed by anti-A antibody in Well 3 reacting with epi-tope A in Wells 1 and 2. The “spur” on the precipitation line at Well 1 that is pointing toward Well 2 is formed by anti-B antibody reacting with epitope B in Well 1. Anti-B antibody migrates right through the precipitation line formed by anti-A antibody because there is no epitope B in Well 2 for the anti-B antibody to react with.

Explanation:

Campylobacter is a motile, curved, oxidase-positive, gram-negative rod with polar flagella. The illness typically begins 1-7 days following ingestion of the organism. The presentation is usually lower abdominal pain and diarrhea with blood and pus. The illness is self-limited after 3-5 days and can last up to 2 weeks. The organisms grow optimally at 42°C under microaerophilic conditions. Escherichia coli is a flagellated gram negative, oxidative negative organism. It is not a common cause of bloody diarrhea in this age group. Salmonella and Shigella are incorrect because they are oxidase negative. Vibrio cholerae has many physical features in common with C. jejuni. However, V. cholerae is not enteroinvasive and does not produce bloody diarrhea, but “rice water” stools.

Explanation:

The disease is tuberous sclerosis, an autosomal-dominant disease in which cortical hamartomas known as tubers can be associated with facial angiofibromas (adenoma sebaceum), “ash leaf” spots, which are hypopigmented patches on the skin. Patients are at risk of cardiac rhabdomyomas (probably actually a skeletal muscle hamartoma), seizures, mental retardation, and astrocytomas. Associate acoustic neuromas with neurofibromatosis type II.
Associate berry aneurysms with adult polycystic kidney disease. Associate meningiomas with breast cancer and, possibly, high estrogen states. Associate neurofibromas with neurofibromatosis type I.

Explanation:

In this item, the clinical information is really just “window dressing” for the actual question. All you are being asked is, “What is the most common type of cancer seen in the bladder?” The answer is that 90% of primary bladder cancers are transitional cell carcinomas, derived from bladder urothelium (a transitional cell epithelium). Let´s take a moment to review the classic dues associated with bladder carcinoma: exposure to industrial chemicals, cigarette smoking, and infection with Schistosoma haematobium (predisposes to squamous cell type). Remember that a patient´s occupation is usually stated for a reason.
All of the other answer choices are quite rare by comparison.

Explanation:

Explanation:

Gastrin is secreted from the antrum of the stomach when stimulated by parasympathetic nerves and the presence of amino acids in the stomach.
It stimulates: 
-gastric motility 
-growth and acid secretion and 
-intestinal motility.
The secretion of gastrin is inhibited by acid in stomach and somatostatin.

Explanation:

The following would achieve primary prevention of iron deficiency anaemia:

• Provision of adequate iron supplements for premature and low birth weight infants in adequate dosage (2mg/kg of elemental iron per day)
• Not using unmodified doorstep milk in the first year of life. Although breast milk has a low iron concentration, the relative bioavailability is much higher than from modified or unmodified cow´s milk
• Not giving young children tea (this reduced iron´s bioavailability)
• Use of follow on or ordinary infant formulae in the second half of the first year of life
• weaning on to mixed feeding by 6 months of age
• Iron supplementation for all children in high risk groups.

Explanation:

Visceral leishmaniasis (kala-azar) is an endemic disease in several regions of India and sub-Saharan Africa. It is caused by the parasite Leishmania donovani and spread by phlebotomus sand-flies. Leishmaniasis is common in immune-suppressed patients, particularly those infected with human immunodeficiency virus (HIV). There has recently been a substantial increase of cases in the Mediterranean region. It has been estimated that 15% of HIV positive drug users in Spain are infected with Leishmania donovani infantum. Giardiasis and tropical sprue present with gastrointestinal symptoms and malabsorption. Typhoid is an acute illness. Coccidiodomycosis is largely confined to the Americas. Most patients present with pulmonary symptoms although disseminated disease can occur particularly in the immune-suppressed.

Explanation:

Explanation:

Klebsiella pneumoniae can cause a severe necrotizing pneumonia and is associated with alcoholism and debilitated conditions. The other organisms are not as commonly associated with alcoholism.

Explanation:

Compared with the brain, the phylogenetically older spinal cord and peripheral nerves are relatively resistant to the effects of hypoxia. Effects of hypoxia on the central nervous system are related to the acuity with which hypoxia develops. Acutely, hypoxia produces a picture similar to acute alcohol intoxication, with impaired judgment and motor incoordination. With chronic hypoxia, fatigue, drowsiness, apathy, inattentiveness, delayed reaction time, and impaired work capacity are commonly observed. As the severity of hypoxia increases, brainstem respiratory centers are affected, producing death from respiratory failure. In the lung, hypoxia produces pulmonary artery vasoconstriction.

Explanation:

Ankylosing spondylitis, with its association with HLA-B27, is an autoimmune disorder, which commonly presents initially with chronic low back pain in young adult males. Over time, patients with ankylosing spondylitis are unable to move their back or chest due to involvement in the costovertebral joints. Osteoarthritis is not associated with HLA-B27 positivity. Caplan´s syndrome is an arthritis associated with pneumoconiosis; there will be no back pain associations. Psoriatic arthritis is associated with dermatologic signs, which were not present in this patient. Finally Behcet´s syndrome is characterized by arthritis with oral and genital ulcers, as well as involvement of the central nervous system.

Explanation:

Mining, especially of coal, is strongly associated with pneumoconiosis, a form of COPD. The other occupations do not place individuals at greater risk for COPD.

Explanation:

Ki-67 is a nuclear factor (of uncertain function) whose expression correlates with neoplastic replicative activity. Its expression can be visualized by immunostaining of formalin fixed, paraffin-embedded sections. Ki-67 labeling correlates with a neoplasm´s rate of growth and, therefore, with prognosis. The bcl 2 gene suppresses apoptosis by different mechanisms. Its abnormal activation is involved in the pathogenesis of low-grade lymphomas but not astrocytomas. GFAP is an intermediate cytoskeletal filament (analogue of keratin and vimentin) expressed exclusively by certain types of glial cells, e.g. astrocytes and ependymal cells. Immunohistochemistry for GFAP is mod diagnostically to confirm an astrocytic origin of a neoplasm, but gives no information about mitotic or proliferative rate. The gene p53 encodes a protein that blocks the cell cycle when damage to DNA occurs. If the damage is successfully repaired, p53 allows the cell cycle to resume; if not, p53 induces apoptosis, thus eliminating dangerous DNA mutations. Mutations of p53 have been found in the great majority of human neoplasms, including gliomas. However, its expression gives no information concerning neoplastic replicative activity. Ubiquitin is a low molecular weight heat shock protein. Its function is to tag aberrant proteins for degradation. It is present in many abnormal intraneuronal inclusions associated with neurodegenerative disorders, such as Lewy bodies, Pick bodies, and neurofibrillary tangles. It has no relationship with mitotic activity or growth rate.

Explanation:

This is a multistep microbiology question that requires you to diagnose the illness, identify the microorganism, and remember its key feature. The first part should be easy: everything about this vignette suggests toxic shock syndrome. The organism in question is therefore Staphylococcus aureus, which is coagulase-positive. All the other choices are classic features of other important pathogenic microorganisms: Acid-fast organisms are associated with mycobacteria. (In addition, Nocardia species are partially acid fast.) EMB agar refers to a selective and differential medium used to isolate and identify enteric gram negative bacteria. Gram-positive bacteria will not grow on EMB agar because the addition of eosin inhibits their growth. Nonlactose fermenters will have colorless colonies; fermentation of this sugar will cause the colonies to appear pink or purple. Thayer Martin media can be used for pathogenic Neisseria species. This growth medium contains the antibiotic vancomycin, which kills gram-positive organisms such as Staphylococcus aureus. The Quellung reaction can be used to identify the capsule type of a microorganism. Encapsulated are mixed with specific antisera. If the antibodies recognize the microorganism´s capsule type, the capsule will swell.

Explanation:

Spongiosis is the name used for intercellular edema of the epidermis. Fluid accumulates between the cells, pulling them apart. However, the intercellular connections (desmosomes) remain largely intact. This produces a distinctive microscopic appearance in which each cell is surrounded by a broad white band with tiny dark cross-stripes, somewhat reminiscent of a closed zipper.
Acantholysis is the process of cell separation seen in some blistering diseases. The intercellular connections are broken in acantholysis, producing “rounded-up” cells that are dissociated from each other. Acanthosis is a marked thickening of the epidermis due to an increase in the number and size of the epithelial cells. Hyperkeratosis is an increase in the thickness of the superficial keratin layer of the epidermis. The term parakeratosis is used when nuclei are present in the normally anuclear superficial keratin layer.

Explanation:

The venous system serves as an important blood reservoir for the circulation. When blood is lost from the body and blood pressure begins to fall, pressure reflexes are elicited that send sympathetic nerve signals to venules and veins, causing them to constrict. By “tightening” the circulation and taking up much of the “slack” caused by the blood loss nearly normal function can usually be restored with up to a 20% loss of blood volume. The mean systemic filling pressure (MSFP) is the pressure that exists in all parts of the circulation when the heart has been stopped and the blood volume has become redistributed in the system until all pressures are at equilibrium. The MSFP is thus a measure of the “tightness” with which the circulatory system is filled with blood. The more the system is filled (i.e., when MSFP increases), the easier it is for blood to flow into the heart, which tends to increase venous return. Constriction of the arterial system has relatively little effect on mean systemic filling pressure because the arterial system contains a relatively small volume of blood. Capillaries do not constrict because they do not contain smooth muscle cells in their walls.

Explanation:

This question first requires you to make the connection between cystic fibrosis (CF) and bleeding. The connection is that CF patients have problems with pancreatic exocrine secretions and therefore have fat malabsorption, which, in turn, results in malabsorption of the fat-soluble vitamins A, D, E, and K. Vitamin K is essential in the post-translational modification of factors II (prothrombin), VII, IX, X, and proteins C and S. Factors V, VIII, and XII are not vitamin K dependent. Although protein C and protein S are vitamin K dependent, these proteins are endogenous anti-coagulants involved in clot lysis, not clot formation. Therefore, deficiency of protein C would cause thrombosis, not bleeding.