Explanation:

Kaposi sarcoma is a spindle cell neoplasm that is highly associated with AIDS and with the Herpes simplex virus type 8. The tumor has an appearance very similar to that of angiosarcoma-proliferating stromal cells and endothelium creating vascular channels that contain blood cells. Carcinosarcoma is a tumor that contains malignant epithelial cells and malignant stromal cells. There is no epithelial element in Kaposi sarcoma. Although lymphoma occurs with increased frequency in AIDS, it does not resemble Kaposi sarcoma. Lymphoma involves neoplastic lymphocytes, whereas Kaposi sarcoma involves neoplastic vascular structures. Malignant fibrous histiocytoma (MFH) is an extremely poorly differentiated (anaplastic) stromal malignancy. MFH does not produce any recognizable mesenchymal structures; thus, the production of vascular structures by Kaposi sarcoma differentiates the two tumors. Melanoma does produce colored skin lesions; however, the histologic appearance of the malignant melanocytes is quite unlike Kaposi sarcoma. Melanoma in situ appears as small nests of cells with large, red nucleoli in the dermis and epidermis; this lesion can progress to a variety of forms but none resemble Kaposi sarcoma.

Explanation:

Explanation:

A pheochromocytoma is a tumor arising from chromaffin cells located in the adrenal medulla, which secretes catecholamines (norepinephrine, epinephrine, or both). It is one endocrine cause of hypertension, due to peripheral vasoconstriction and/or increased cardiac output. While most patients have higher than normal baseline plasma levels of catecholamines, it is not uncommon for paroxysmal symptomatic episodes to be superimposed upon the basal problem. These “attacks” may occur several times a week (or more often) and last for up to 15 minutes. During an attack, respiration can increase, the patient may become aware of a forceful pounding of the heart that progresses to include a throbbing headache, and peripheral vasoconstriction can raise body temperature and lead to reflex sweating. Marked anxiety may also accompany the episode. Diagnosis can be confirmed by measuring increased plasma or urinary catecholamines or their metabolites. The juxtaglomerular complex is composed of specialized distal renal tubular cells called macula densa cells. These are responsive to chloride concentration as well as pressure within the wall of the afferent and efferent arterioles. The substance produced is renin, not catecholamines. The zona fasciculata produces glucocorticoids. The zona glomerulosa produces aldosterone. An increase in blood pressure can result from excessive renal retention of sodium and water resulting from the increased plasma concentration of aldosterone. The paroxysmal symptoms and increased catecholamines present in this patient are not associated with primary hyperaldosteronism. The zona reticularis primarily produces androgens

Explanation:

This woman has developed genital warts caused by human papillomavirus. The mechanism of oncogenesis in this virus is well understood. The virus produces two proteins, E6 and E7, which combine with and inactivate two cellular anti oncogenes (tumor suppressor genes). p53 and p110. Human papillomavirus has a yew strong association with the development of cervical intraepithelial neoplasia. Retinoblastoma is a cancer that results from the inactivation of two cellular anti-oncogenes. Burkitt lymphoma is a malignancy that is believed to result from the translocation of the c-myc oncogene region of chromosome 8 to the long arm of chromosome 14, near the site where there is heavy transcriptional activity for the immunoglobulin heavy chain. These translocations occur at a higher frequency in cells infected with Epstein-Barr virus, and malaria seems to act as a cofactor. HTLV-1 leukemia is believed to occur via an oncogene capture or provirus insertion mechanism. In this way, a virus with a yew active transcriptional promoter/enhancer region may integrate near a cellular oncogene, resulting in malignant transformation. Kaposi sarcoma is a malignancy associated with infection with human herpesvirus 8 as a cofactor, especially in HIV infected individuals. The mechanism of oncogenesis has not been determined. Primary hepatocellular carcinoma is a malignancy associated with hepatitis B and C infections. The mechanism of oncogenesis has not been determined.

Explanation:

Explanation:

Venous thrombosis is attributed to three predisposing factors. The first factor is stasis of blood, which may occur with prolonged immobilization, such as prolonged travel or which may occur in any condition associated with prolonged bed rest, such as a cerebrovascular accident or during surgery requiring more than 30 minutes of anesthesia. The second factor is hypercoagulability of blood, such as that occurring with Antithrombin III deficiency protein S. and protein C deficiencies. The third factor is abnormality of the vessel wall, resulting in endothelial injury, such as that caused by chronic venous insufficiency. Estrogens, but not progestins, are associated with an increased risk of venous thrombosis, with the risk apparently related to dose.

Explanation:

Apoptosis is a form of cell death that serves to eliminate unwanted, cells during development maintain cell numbers in intact organs or tissues, and eliminate immune cells after an immune response has faded. Apoptosis also occurs in response to noxious agents and in the aging process. In the prostate, it occurs after removal of androgenic stimulation from the testes. The process is the result of execution of an internal program mediated by the expression of a number of different genes. In the process of apoptosis, cells shrink and cytoplasmic organelles become more densely packed. Cytoplasmic blebs may form, and apoptotic bodies (membrane-bound cellular fragments) can be produced. The most characteristic feature of apoptosis is a distinctive peripheral aggregation of chromatin, sometimes accompanied by breaking up of the nucleus into several fragments. In necrosis, the chromatin may become more pale (karyolysis) or form irregular clumps, and the nucleus itself may shrink into a dense pyknotic body. Disaggregation of polyribosomes is characteristic of the initial stages of cellular injury and necrosis. Eosinophilia characterizes both apoptosis and necrosis. Inflammation is typically absent in apoptosis, in contrast to necrosis.

Explanation:

Maternal age is the greatest risk factor for Down´s syndrome, and the risk rises significantly in women over 35. None of the other conditions is associated with this syndrome.

Explanation:

Hypercalcemia is not associated with poorly controlled diabetes, while all of the other conditions are.

Explanation:

Either fasting or cessation of ingestion of the offending agent prevents the diarrhea. Osmotic diarrhea results from the accumulation of nonabsorbed solutes in the intestinal lumen. It may result from the ingestion of poorly absorbable solutes, such as saline purgatives. Maldigestion of ingested food, such as that occurring in lactase deficiency may also cause it. Failure of a mucosal transport mechanism, such as occurs in glucose galactose malabsorption, may also cause it. These osmotically active agents result in the retention of water and salts within the intestinal lumen.

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:

Abscesses are commonly produced by catalase positive organisms. Catalase is an enzyme that converts hydrogen peroxide into water and oxygen. Hydrogen peroxide is one of the toxic oxygen compounds generated by the action of NADPH oxidase in phagocytes and acts is the substrate for myeloperoxidase, so producing catalase allows bacteria to survive longer intracellularly. Catalase positive organisms include the staphylococci, Pseudomonas, Candida, Aspergillus, and the Enterobacteriaceae. Hemolysins are toxins that can lyse erythrocytes.
Hyaluronidase is an enzyme produced by Group A streptococci that splits hyaluronic acid in ground substance. Streptokinase is a streptococcal enzyme that transforms plasminogen into plasmin. Tetanospasmin is a clostridial neurotoxin that inhibits GABA and glycine and causes rigid paralysis.

Explanation:

The tuberculin response is the classic example of type IV hypersensitivity, which is mediated by TH1 cells and macrophages. The initial recognition signal involves interaction between MHC class II and the T cell receptor. The B7 molecule on the cell surface of the antigen presenting cell reacts with the CD 28 molecule on the T cell surface for maximal costimulatory signals. The B7 molecule on the surface of the antigen presenting cell reacts only with CD 28 and does not react with LFA-1 adhesion molecule. The ICAM-I on the surface of an antigen presenting cell reacts with the LFA- I on the surface of a T cell for the purpose of cell-to-cell adhesion and does not function for costimulation. LFA-3 (CD58) is an adhesion molecule on the surface of an antigen presenting cell. It does not react with a CD28 costimulatory molecule on the T cell surface. The MHC class II molecule with its epitope does interact with a specific T cell receptor (TCR) but this is not termed costimulatory. However, the interaction does stimulate the T cell to produce interleukins for further cell division.

Explanation:

Recurrent miscarriages in the first trimester are usually indicative of a chromosomal abnormality. Among these Robertsonian translocations are most common. Major chromosomal deletions or genetic mutations are unlikely since the carrier (the mother) appears to be healthy. Robertsonian translocations involving chromosome 14 and 21, for example, are not only a common cause of Down syndrome, but may also lead to recurrent abortions. While advanced maternal age (greater than 35 years old) may increase the risk of Down syndrome, several consecutive first-trimester abortions are unlikely. Paternal age is rarely a cause of recurrent abortions. She cannot have an autosomal monosomy because that would be incompatible with life. A person with a bicornuate uterus may also suffer from recurrent abortions, although recurrent first trimester abortions are most likely related to a chromosomal abnormality.

Explanation:

Chronic inflammatory conditions, such as collagen vascular diseases, rheumatoid arthritis, and bronchiectasis, may lead in time to accumulation of a specific form of amyloid known as AA (amyloid associated protein). Systemic amyloidosis affects many organs, especially the heart, kidneys, spleen, GI tract, liver, and tongue. The ventricular walls become thickened and inelastic, and the resulting pathophysiologic picture is that of restrictive cardiomyopathy. Congestive heart failure ensues because of decreased ventricular compliance and secondary reduced stroke volume. Note how the ventricular lumina are narrowed and the walls are extremely thickened. A waxy texture is highly suggestive of amyloid deposition which can be confirmed histologically by using Congo red staining. Atherosclerosis of coronary arteries may give three different types of clinical manifestations: arrhythmias (with sudden death), angina pectoris, and myocardial infarction. Loss of myocardial tissue due to ischemic necrosis may lead to congestive heart failure. The heart will show evidence of old infarcts in the form of scars, and the ventricular cavities will become dilated.
Coxsackievirus myocarditis is the most common etiologic form of viral myocarditis, which may resolve without clinical consequences or lead to dilated cardiomyopathy and heart failure. Mutations of myosin chain genes are the most common causes of hypertrophic cardiomyopathy. This manifests with thickening of the interventricular septum (so called asymmetric cardiac hypertrophy), with resultant impediment to both systolic outflow and diastolic filling. Here, the ventricular walls are uniformly thickened and the remaining postmortem findings (liver, kidney, and spleen changes) cannot be explained based on a diagnosis of hypertrophic cardiomyopathy. Systemic hypertension in the early stages is associated with cardiac hypertrophy, but progressive ventricular dilatation develops with decompensation. In a patient dying of hypertension related heart failure the heart is usually large (hypertrophic) and the ventricles are markedly dilated.

Explanation:

In general, a “renal failure diet” is designed to control the amount of protein and phosphorus in patient´s diet. Furthermore, patients may be instructed to limit the amount of sodium and total fluid intake. In summary, a renal failure diet, provided there are no other contraindications to this recommendation should be low in protein (Options A, C, D and E are incorrect). Although the ingestion of 3 to 4L of fluid on a daily basis is recommended for adults with normal renal function, the GFR and subsequent elimination of water are decreased in patients with renal dysfunction. A patient with renal dysfunction and/or renal failure who ingests this volume of fluid on a daily basis is likely to develop peripheral edema. Therefore, a dietician would most likely recommend that a patient with chronic renal failure should have a diet; that consists of high carbohydrate and moderate fat intake as well as low amounts of sodium and phosphorus.

Explanation:

The most distinctive clue is the presence of amyloid, which specifically suggests medullar thyroid carcinoma. This carcinoma is a tumor of the neuroendocrine parafollicular cells of the thyroid, rather than the follicular lining epithelium, These cells produce calcitonin, the precursor protein of which can precipitate, forming bands and nodules of amyloid that appear histologically identical to other forms of amyloid. The other thing to remember about medullary carcinoma of the thyroid is that it can be a component of multiple endocrine neoplasia (MEN) syndromes type IIa (parathyroid disease, pheochromocytomas, medullary carcinoma) and type IIb (parathyroid disease, pheochromocytomas, medullary carcinoma, mucocutaneous ganglioneuromas, Marfanoid habitus).
Because follicular thyroid carcinoma closely resembles normal thyroid tissue, it usually cannot be reliably diagnosed based on fine-needle aspiration alone. Hashimoto disease would show lymphocytes, plasma cells, and macrophages on aspiration. Papilla thyroid carcinoma can be diagnosed by aspiration if papilla clusters are seen. Thyroid adenoma cannot be reliably distinguished from well differentiated thyroid carcinoma on aspiration.

Explanation:

CEA is a glycoprotein (200,000 daltons) that is found in the gastrointestinal mucosal cells and pancreatobiliary system secretions. It becomes elevated when breaks in the mucosal basement membrane occur due to tumor growth. Some other conditions can also cause elevations of CEA (e.g., cirrhosis, pancreatitis). The patient described above has colonic carcinoma, and the “apple core” lesion is the classic radiographic finding of this tumor. Although CEA is not used for screening because of the large number of false positives, it can be used to guide treatment in known cases. It returns to normal levels 30-45 days after tumor resection. If it begins to rise again, tumor recurrence is likely. AFP, or alpha-fetoprotein, is an alpha globulin (70,000 daltons) made by the liver and yolk sac of the human fetus. It is elevated with hepatocellular carcinoma and germ-cell neoplasms. It is not particularly specific. hCG, or human chorionic gonadotropin, is a glycoprotein secreted by trophoblastic epithelium of the placenta. It is useful (sensitive and specific) for germ-cell tumors of the testis and ovary. LDH, or lactate dehydrogenase, is avert nonspecific test that can be elevated in many conditions, including malignancy. PR, or progesterone receptor, is an immunohistochemical marker used when evaluating breast cancers.

Explanation:

The central neurons system and its overlying bones are subject to a variety of malformations and developmental diseases. The defect described in the question stem is a cranial encephalocele, in which brain herniates through a defect in the skull bones. The most common site for such a herniation is the occipital bone. Small defects in the occipital bone can be treated surgically, but large detects are very problematic, particularly if significant herniation has occurred, since the brain becomes very vulnerable to trauma and infection. Meningocele is the term used when the meninges, but not the brain or spinal cord, herniate through a defect in the bony cranium or spinal column. Myelocele is the term used when the spinal cord herniates through a defect in the spinal column.
Spina bifida refers to vertebral detects through which the spinal cord or meninges may herniate. Syringomyelia is a tubular, fluid-filled cavity within the spinal cord.

Explanation:

This patient has Goodpasture syndrome which is a rare, severe, autoimmune disease in which antibodies directed against the basement membrane in pulmonary alveoli and renal glomeruli predispose for hemoptysis and progressive renal disease. These patients can die because of exsanguination, asphyxiation by blood, or renal failure. Aggressive immunosuppression coupled with management of complications may be lifesaving. Goodpasture disease is often cited as an example of a type II hypersensitivity reaction, and a very similar pathologic mechanism produces the blistering disease bullous pemphigoid, in which antibodies are directed against the basement membrane region of the skin. The immunologic basis of Graves disease is stimulation of TSH receptors by antireceptor antibodies. The immunologic basis of hereditary angioedema is inadequate Cl esterase inhibitor activity. The immunologic basis of rheumatoid arthritis is the presence of immune complexes within joints. The immunologic basis of serum sickness is circulating immune complexes.

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:

Pseudohypoparathyroidism is due to end organ insensitivity to PTH. This results in hypocalcemia, hyperphosphatemia, and decreased serum levels of 1, 25 (OH)2 vitamin D, as would be expected for primary hypoparathyroidism. However, serum PTH concentration is increased as a normal response to the low serum calcium. The biochemical detect in some of these patients has been shown to be decreased expression of Gs. Since PTH acts by increasing intracellular cAMP, the reduction in Gs could explain the target-cell unresponsiveness. Failure of injected PTH to increase urinary cAMP can confirm the end organ insensitivity. The cause of the developmental defects (mental retardation, shortened metacarpals or metatarsals, etc.) is not known. Primary hyperparathyroidism presents with hypercalcemia and hypophosphatemia due to increased serum concentration of PTH. Primary hypoparathyroidism also presents with hypocalcemia, but is associated with decreased serum PTH. Furthermore, kidney responsiveness to injected PTH should be normal. Pseudopseudohypoparathyroidism is a rare genetic disorder. These patients present with the same developmental defects as in pseudohypoparathyroidism, but have normal serum levels of calcium and PTH. In vitamin D deficiency, serum calcium may be decreased and serum PTH increased. However, serum phosphate is usually decreased. This is partly due to the decrease in absorption of dietary phosphate and partly due to increased renal excretion of phosphate because of the increased PTH. Furthermore, the developmental detects and end-organ insensitivity to PTH would not be present with vitamin D deficiency.

Explanation:

Two of the secretions of the anterior pituitary affect the sensitivity of peripheral tissues to the action of insulin. Growth hormone has a direct effect on liver and muscle to decrease insulin sensitivity. This may be partly through a growth hormone induced decline in insulin receptors or to unknown post-receptor defects. In excess, growth hormone is “diabetogenic and about 25% of patients with acromegaly have diabetes. ACTH indirectly has anti insulin effects by virtue of the cortisol secretion it evokes. Like growth hormone, cortisol also decreases insulin sensitivity in peripheral tissues. A third anterior pituitary hormone, TSH, also tends to increase blood glucose levels. In this case, the effect is probably mediated mostly through increased glucose absorption by the gut. Patients with hyperthyroidism can sometimes exhibit a postprandial glucosuria because of excessive intestinal glucose absorption. In diabetic animals, the removal of the anterior pituitary may lower blood glucose by increasing tissue sensitivity to whatever insulin remains. Removal of the colon should have little effect on blood glucose since dietary glucose is absorbed in the small intestine. Sex steroids secreted by the gonads have little effect on blood glucose concentration. The kidney plays an important role in reabsorbing filtered glucose. In diabetes, the tubular reabsorption maximum is exceeded and glucose spills over into the urine. The loss of glucose in the urine helps to reduce the severity of the plasma hyperglycemia. Removal of the kidneys would, if anything, make the hyperglycemia worse. Pancreatectomy would make the hyperglycemia worse by removing the source of any remaining insulin.

Explanation:

Explanation:

The antigenic challenge in this case would result in activation of B lymphocytes and production of antigen-specific immunoglobulins. The B dependent areas of lymph nodes would consequently become hyperplastic. These are the germinal centers of lymphoid follicles, where maturation of B cells takes place. Thus, a picture characterized by enlargement of germinal centers develops. This is called follicular hyperplasia. Necrotizing lymphadenitis is seen in a few specific infections (namely tularemia, bubonic plague, anthrax, and typhoid fever) and in Kikuchi lymphadenitis, a rare noninfectious form. Paracortical lymphoid hyperplasia refers to hyperplasia of the interfollicular zones, which are predominantly populated by T cells. This change is seen in response to phenytoin, viral infections, and antiviral vaccinations. Sinus histiocytosis is characterized by enlarged lymphatic sinuses filled with reactive histiocytes. This nonspecific change is seen frequently in nodes draining sites with chronic infections or a neoplasia. Stellate abscesses occur in nodes involved by cat-scratch disease, tularemia, and lymphogranuloma venereum.

Explanation:

Fistulas between the gastrointestinal tract and the hip joints are very rare, but clearly this man has developed one. Crohn disease is notorious for its propensity to develop fistulas. These are typically within the abdomen, but they can form at rather unexpected locations, like this one. His age, ethnicity, and prior history are highly suggestive for this diagnosis. An appendiceal abscess could eventually point into the groin, following the psoas muscle. Such migration of pus would occur on the right side rather than the left, however, and it would produce a groin mass rather than a septic hip. There would not be a history extending for 10 years. Chronic ulcerative colitis rarely fistulizes and often has bloody diarrhea. Sigmoid diverticulitis can fistulize, but usually it does so into the urinary bladder. It is preferentially a disease of older people. It has been described in young, obese men of Mexican American decent. This patient does not fit the profile. It would be quite a surgical tour de force to get into the bowel by way of the hip joint, but even if we assume that such complication could occur, we must remember that in this case the hip joint had become infected before an operation was performed.

Explanation:

Explanation:

diopathic thrombocytopenic purpura (ITP) classically occurs acutely in children several weeks after a viral infection (a viral exanthem or upper respiratory infection in 70% of cases) and is the most common thrombocytopenic purpura of childhood. Physical examination findings usually include easy bruisability, mucous membrane bleeding, gastrointestinal or genitourinary bleeding, and petechiae. CNS bleeding may occur. The peripheral smear typically shows a few, large, young platelets. The other cell lines are normal.
Disseminated intravascular coagulation is an acquired consumption deficiency of clotting factors and platelets, often resulting in fatal thrombosis and hemorrhage.
Hemolytic uremic syndrome generally occurs in children following diarrhea due to Shigella, Salmonella, Escherichia coli O157:H7, or a virus. Patients typically present with renal failure (BUN and creatinine would be abnormal) along with bleeding and anemia. The disease is similar to thrombotic thrombocytopenic purpura (TTP). TTP is associated with fever, renal failure, neurologic changes, and microangiopathic hemolytic anemia. Platelet aggregation leads to the development of microthrombi throughout the vasculature. The peripheral smear shows few platelets, fragmented red blood cells (schistocytes), and helmet cells.

Explanation:

RAI is safe and that is why it is given across all ages as a definitive treatment of thyroxicosis. The most likely side effect of radioactive iodine is hypothyroidism with approx 80% developing hypothyroidism after therapy. There is no evidence to suggest that RAI is associated with any cancers. However, RAI must not be given to pregnant females particularly after the 12th gestational week as it would be taken up the developing foetal thyroid causing fetal hypothyroidism and is considered to be teratogenic. Recurrent laryngeal nerve damage is a potential risk of thyroid surgery, not RAI.

Explanation:

Diabetic mothers are likely to have children with congenital abnormalities depending on pre-conception and first trimester blood sugar control. 40% of Down syndrome babies have atrioventricular septal defects, as this fetus. The double bubble sign suggest duodenal atresia, which again suggests Down syndrome.
GI malformations occur in 6% of Down´s patients-most commonly duodenal atresia and Hirschsprung´s disease.

Explanation:

Multiple violaceous painless lesions are typical of Kaposi´s sarcoma in Caucasians. It is associated with HHV 8. CMV and HHV 10 do not cause multiple violaceous painless lesions. HPV 16 is an oncogenic virus, which causes squamous cell carcinomas. Pox virus causes molluscum contagiosum.

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:

The EL syndrome is rare and, unlike myasthenia gravis which affects mostly women, primarily affects men over the age of 40 and is associated with usually and underlying bronchial neoplasm. Strength usually is reduced in proximal muscles of the legs and arms, producing a waddling gait and difficulty elevated the arms. The disorder is associated with the presence of antibodies against the Voltage dependent Calcium channels.

Explanation:

Rare in Western countries, hepatocellular carcinoma is one of the most frequent cancers in sub-Saharan Africa, Greece, and parts of the Far East. Infection with hepatitis B virus and hepatitis C virus increase the risk of cancer approximately 100-fold. Chronic liver disease, such as cirrhosis of the liver or liver disease resulting from the hemochromatosis, also predispose to the development of this cancer. Ingestion of aflatoxins (mycotoxins produced by Aspergillus flavus) also predisposes to this cancer.

Explanation:

Explanation:

Factitious hypoglycemia occurs in medical personnel and family members of persons with insulin-dependent diabetes mellitus. C-peptide is released on an equimolar basis with endogenous insulin into the portal vein. In insulinoma, the level of C-peptide parallels the high insulin levels. With exogenous insulin administration, endogenous insulin secretion, and along with it, C-peptide secretion is suppressed. Plasma insulin levels are high in both conditions. As a consequence of raised insulin levels, plasma glucose levels are suppressed in both conditions. Sulfonylurea levels are absent in both conditions. Because insulinoma cells frequently do not process proinsulin completely, the proinsulin levels are often elevated in the serum of persons with these tumors.

Explanation:

Tumor suppressors are genes that regulate cell cycle, promote apoptosis, or both. Both copies of the allele must be altered before an effect is manifested two-hit hypothesis). Familial cancers usually result from an inherited defect in one copy of an allele, with subsequent inactivation of the second copy during life. The tumor suppressor gene most strongly associated with ovarian carcinoma is BRCA-1, which is also associated with breast cancer. This tumor suppressor gene is located on chromosome 17q. VHL (3p) is associated with von Hippel-Lindau disease. APC (5q) is associated with colon cancer. p53 (17p) is associated with Ll-Fraumeni syndrome. DPC (18q) is associated with pancreatic cancer.

Explanation:

CA-125 may be elevated in ovarian epithelial tumors, such as a cystadenocarcinoma. AFP can be elevated with either an endodermal sinus tumor or embryonal carcinoma. An elevated hCG can be seen with choriocarcinomas. Sertoli-Leydig and granulosa-theca cell tumors do not usually produce an elevated CA- 125, AFP, or hCG level.

Explanation:

Explanation:

While all of the answer choices may produce pulmonary symptoms, only Coccidiodes immitis produces erythema nodosum. The other findings of backache, flu like symptoms, and pneumonitis are all consistent with a diagnosis of coccidiomycosis.

Explanation:

A common manifestation of Ehlers Danlos syndrome is joint hypermobility. Joints tend to have reduced mobility in osteoarthritis and rheumatoid arthritis, and do not have increased mobility in chondroepiphyseal dysplasia or osteogenesis imperfecta.

Explanation:

Osteomalacia and hypophosphatemia with high renal phosphate clearance occur with several tumors, predominantly of mesenchymal origin. Humoral factors released by these tumors may impair proximal tubular functions, such as 1-alpha hydroxylation of 25(OH) D and phosphate transport. Rickets and osteomalacia are diseases of defective bone and cartilage mineralization. This requires sufficient calcium and phosphate at the mineralization sites. Insufficiency of the active metabolites of vitamin D leads to decreased intestinal absorption of calcium and decreased mobilization of calcium from bone. Vitamin D absorption is impaired in diseases of the small bowel, hepatobiliary tree, and pancreas, which impair the enterohepatic circulation. Chronic renal failure results in decreased conversion of 25(OH) D to 1, 25, (OH)2 D, either as a consequence of insufficient viable renal cortical tissue or an inhibitory effect of hyperphosphatemia on renal 25(OH)D-1-alpha-hydroxylase activity. Hypophosphatasia is a deficiency of alkaline phosphatase, which results from a missense mutation of the alkaline phosphatase gene. Bone disease probably results from failure of alkaline phosphatase to cleave pyrophosphate, an inhibitor of bone mineralization. This leads to elevated levels of inorganic pyrophosphate, which inhibits bone mineralization. Drugs, such as phenytoin and phenobarbital, induce hepatic microsomal enzymes that metabolize 25(OH)D to inactive metabolites, thereby resulting in decreased circulating levels of 25(OH)D.

Explanation:

Diverticula occur most commonly in the sigmoid colon and decrease in frequency in the proximal colon. Congenital diverticula are herniations of the entire thickness of the intestinal wall. By contrast, acquired diverticula are herniations of the mucosa through the muscularis, usually at the site where the nutrient artery penetrates the muscularis. Both increased intraluminal pressure and decreased fiber intake have been postulated to predispose to the development of diverticula.

Explanation:

In children under the age of two years, Gram negative rods such as Echerichia coli and group B streptococcus, such as Streptococcus agalactiae, are important causes of septic arthritis. Although Haemophilus influenzae was formerly a major cause of septic arthritis in young infants, the frequency of H. influenza induced septic arthritis has fallen significantly after the institution of the Haemophilus influenzae type b vaccine.

Explanation:

Turner´s syndrome, 45 XO, is characteristically associated with short stature.
Klinefelter´s is associated with tall stature. In Fragile X, height is usually unaffected and homocystinuria may have a Marfan´s habitus.

Explanation:

Eukaryotes (higher organisms) have multiple chromosomes in the genome which is separated from the rest of the cell by nuclear membranes. Prokaryotes lack a membrane bound nucleus, and their DNA occurs in a circular form.
Transcription of eukaryotic genes requires non-coding sequences (introns) in the mRNA to be spliced out before translation at the ribosome. Both eukaryotes and prokaryotes have a ribosome, though the ribosome is significantly larger in eukaryotes.

Explanation:

This is Behcet´s disease. It is associated with increased risk of thrombosis. It is linked to HLA B5.

Explanation:

Poisons that can cause Parkinsonism include:
– manganese
– carbon monoxide
– carbon disulfide
– the cycad nut and
– The illicit drug MPTP (methyl-phenyl tetrahydropyridine).

There are also other diseases of the brain that combine Parkinsonism. Includes
– Wilson´s disease
– Huntington´s disease
– Shy-Drager syndrome
– Striatonigral degeneration
– Olivo-ponto-cerebellar degeneration
– Cortical-basal ganglionic degeneration
– Progressive supranuclear palsy
– Diffuse Lewy body disease
– Creutzfeldt- Jacob disease and even
– Alzheimer´s disease.

Explanation:

Explanation:

The HACEK organisms are minor pathogens that are a cause of a significant minority of bacterial endocarditides. They are: Haemophilus aphrophilus, Haemophilus parainfluenza, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae. Haemophilus influenza is not a HACEK organism.

Explanation:

Explanation:

CNS toxoplasmosis infection is the most common cause of a ring-enhancing lesion in the brain of an AIDS patient. Five percent of patients will not have a positive toxoplasmosis anti- body titer in the serum. A focal neurologic deficit is the most common initial presentation. Cryptococcal meningitis presents with nuchal rigidity, fever, and photophobia. It would not present as a ring enhancing lesion. Tuberculoma would be rare unless other signs of tuberculosis are present. Cerebral infarct would not be common in someone this young. Hodgkin´s lymphoma usually spreads to the hilar and retro peritoneal lymph nodes. CNS non Hodgkin´s lymphoma occurs in 25% of AIDS patients with a ring enhancing lesion in the brain

Explanation:

Virulence factors are more common in uncomplicated infections than in complicated ones, presumably because host resistance must be overcome in the former. Strains of E. coli are more likely to contain K antigens (capsular polysaccharides), which resist phagocytosis. Both E. coli and Proteus contain fimbriae, which mediate their attachment to specific receptors on epithelial cells. Production of hemolysin also increases virulence. Urease producing bacteria, such as Proteus, Providencia, and Corynebacterium D2, are especially virulent because they produce ammonia, which is toxic to the kidney.

Explanation:

Newly formed bone is often woven rather than lamellar, and is structurally less competent. Osteitis deformans (Paget´s disease of bone) is characterized by increased metabolic activity of bone surfaces. Bone remodeling at affected sites may be increased five to ten fold. Osteoclasts contain multiple pleomorphic nuclei, are increased in size, and contain cytoplasmic inclusions which resemble viral nucleocapsids, suggesting a viral etiology for this disease. Although osteoclast competence is decreased, there is an overall increase in bone resorption due to the marked increase in number of osteoclast like cells. Even though increased bone resorption enhances release of calcium and phosphate ions, their reutilization, in part, helps maintain normal plasma calcium levels.

Explanation:

All of the clinical findings point to the diagnosis of Buerger´s disease. Buerger´s disease, or thromboangitis obliterans, is a disease of smokers in their middle age. It typically affects mediumsized arteries and causes gangrene, ulcerations, and pain of the extremities, which typically house these arteries.

Explanation:

Explanation:

This patient has cryptosporidiosis. The causative protozoan, most often Cryptosporidium parvum, infects the brush border of the small intestine. Although the disease is usually self limited in healthy individuals, in AIDS patients it can cause severe diarrhea with fluid losses in the 5 to 10 liters/day range. The mechanism of causation of diarrhea is through the direct lysis of cells of the brush border as the intracellular parasites multiply there. The diarrhea may continue persistently or intermittently until the patient´s death. Stool concentration techniques increase the chance of indenting the characteristic acid fast oocysts in stool. Invasion into the submucosa is observed with organisms such as Entamoeba histolytica and Shigella dysenteriae among others. Invasive organisms cause diarrhea that is bloody and filled with neutrophils. Stimulation of neutrophilic infiltrate is also a finding in invasive organisms because neutrophils are attracted to the area of bowel wall destruction. Intracellular organisms such as Cryptosporidium are not major attractors of neutrophils. Toxins that inactivate the 60S ribosomal subunit include the Shiga toxin of Shigella dysenteriae and the verotoxin of enterohemorrhagic Escherichia coil. Most intracellular parasites such as Cryptosporidium do not produce exotoxins. A toxin which ribosylates Gs is produced by enterotoxigenic .Escherichia colt Cryptosporidium is not known to produce any exotoxins.

Explanation:

A virus is isolated from a painful blister on the lip of teenage girl. The agent is found to have double-stranded, linear DNA and is enveloped. A similar sore occurred in the patient approximately 2 months ago. Feature that is unique to the life cycle of the infectious agent is

Explanation:

Influenza and other viruses with segmented genomes (reovirus, orthomyxovirus, bunyavirus, and arenavirus) are capable of genetic reassortment. This is an accidental “shuffling” of the segments of genomic RNA, so that new genetic combinations can be produced. Viruses that have segmented genomes have multiple pieces of RNA that must be assembled correctly in the progeny to produce a new generation that is identical to the parental generation. When accidental rearrangements occur, genetic shift results; and in influenza, this is responsible for the production of pandemics of disease. Complementation occurs when two viruses infect a single cell. If one is defective in a certain gene product, progeny viruses can be produced as long as that defect can be “complemented” by the makeup of the other virus. If both viruses have the same defect, no progeny viruses can be produced. In the case given above, two viable viruses were grown in a single cell and new combinations of surface molecules were produced. Genetic drift refers to random mutational changes that can occur in any reproducing organism. These changes can change the surface of the organism, which affects the host immune response to the organism. Changes, such as these, are more gradual than genetic shift, and are best described in viruses, such as HIV. Phenotypic masking refers to occasions in which two related viruses infect a cell, and the capsid produced in the progeny generation is created from the genome of one of the viruses, while the genome included in the capsid is from the other virus. Thus, one genome is “masked” or covered with the antigens of the other virus. In the case described above, combinations of surface molecules were expressed. Phenotypic mixing refers to occasions in which two related viruses infect a cell and the capsid produced in the progeny generation is a mixture of the capsid antigens from the two parental viruses. Since the genomic RNA is not actually reassorted in this case, this would not be a stable genetic change, but simply a reflection of the antigens of both parental viruses being inserted on the surfaces of a single progeny 

Explanation:

The most important chemotactic factors for neutrophils are the complement factor C5a and the interleukin-8.
The cytokines IL-1 and tumor necrosis factor have complex similar actions including stimulation of production of many acute-phase reactions, stimulation of fibroblasts, and stimulation of endothelium. Leukotrienes LTC4 and LTD4 cause increased vascular permeability. Prostaglandins PGI2 and PGD2 mediate vasodilation and pain. Thromboxane and platelet activating factor promote vasoconstriction and platelet aggregation.

Explanation:

The entity demonstrated in the picture is hydatidiform mole specifically complete mole. Hydatidiform mole is due to abnormal proliferation of trophoblastic tissue. Complete mole results from a process known as androgenesis in which an empty egg is fertilized by a sperm and contains a diploid karyotype. This form will progress to an invasive mole (which infiltrates deeply into the uterine walls) in 10% of cases and to choriocarcinoma in 2% of cases. Partial mole has a triploid karyotype and originates from fertilization of an ovum with one or two sperm. Partial moles are entirely benign and progress to choriocarcinoma in exceptional instances. Histologically, complete mole is characterized by complete absence of vessels within most of chorionic villi and absence of fetal parts. Partial mole, on the other hand, is associated with hydropic degeneration of only a part of chorionic villi and presence of identifiable fetal parts. Carcinoma of the endometrium has no relationship with pregnancy and manifests usually after menopause. Nulliparity, obesity, diabetes mellitus, and any source of unopposed hyperestrinism (whether natural or iatrogenic) are predisposing factors. Eclampsia is a pregnancy related complication that manifests characteristically in the third trimester. It encompasses a clinical syndrome of varying severity from mild cases of hypertension and proteinuria, to severe cases of hypertension, proteinuria, edema, and seizures. It is pathogenetically related to defective maturation of the vasculature of chorionic villi, with resultant placental ischemia and release of vasoconstrictor substances. Sarcoma botryoides has a gross appearance superficially reminiscent of complete mole. This malignant tumor predominantly affects children and may appear as a grapelike mass of tissue that protrudes through the vagina. Neoplastic cells are of skeletal muscle origin (the proper name of the tumor is embryonal rhabdomyosarcoma). On H&E, neoplastic cells appear small and undifferentiated. Yolk sac tumor is a malignant neoplasm of germ cell origin. It develops in children and young adults, either in the ovary or the testis. It is composed of tissue that resembles primitive yolk sac.

Explanation:

Grade refers to the severity of the microscopic changes. The presence of well formed glands establishes the tumor as well differentiated, or low grade (high grade would be poorly differentiated). Stage refers to the degree of dissemination of the tumor (i.e. confinement to the mucosa vs. extension into or penetration through the muscularis propria, presence or absence of metastases). A tumor that grows through the colonic wall and has metastasized is high stage.
A high-stage high-grade tumor would be exemplified by one that metastasizes to the liver (high stage) and demonstrates poor differentiation marked nuclear atypia, and a lack of glandular formation (high grade). A low-stage high-grade tumor would be exemplified by a poorly differentiated adenocarcinoma (nuclear atypia, lack of tubule formation) confined to the mucosa or submucosa. A low-stage, low-grade tumor would be exemplified by a well differentiated tubule-forming adenocarcinoma that is confined to the mucosa or submucosa

Explanation:

Explanation:

The probable organism is Giardia lamblia which characteristically infects the small intestine. When seen in smears from duodenal aspirates, this flagellated organism has a characteristic “face like” appearance. However, in biopsy specimens the organism is often caught at an angle, and the characteristic appearance and location is as described in the question stem. Giardia is a common contaminant of water supplies, and patients who ingest the cysts may be asymptomatic or may occasionally develop prolonged diarrhea or intestinal malabsorption. Some patients with severe disease have low serum IgA or low overall immunoglobulin levels. Entamoeba histolytica usually infects the large intestine and/or liver. Escherichia coli is a bacterial cause of diarrhea. Naegleria fowleri causes meningoencephalitis. Trichomonas vaginalis causes vaginitis.

Explanation:

Proteus species produce urease, which raises the urinary pH and promotes the production of struvite stones. Escherichia coli is by far the most common cause of urinary tract infections but is not responsible for the development of struvite stones. Pseudomonas aeruginosa can also cause urinary tract infections, most commonly in hospitalized or immunocompromised patients (especially burn patients, patients on immunosuppressives/antimicrobials, and cystic fibrosis patients). It does not predispose to struvite stones. Staphylococcus saprophyticus is a common cause of urinary tract infections in sexually active young women. Ureaplasma urealyticum can produce urease (like Proteus), but it is responsible for urethritis, not stones.

Explanation:

The nurse´s elevated IgM anti-HBc indicates that she was infected with hepatitis B. Formerly, HBsAg (surface antigen) and anti-HBsAg (antibody to surface antigen) were used exclusively to determine this. Typically, HBsAg is positive for up to 6 months, and anti-HBsAg is positive for years after that. Unfortunately, this simple scheme has the disadvantage that many patients have a 2 week to 4 month “window” period, when the surface antigen (HBsAg) and the antibody (anti-HBs) are not detectable. Presumably, for a relatively brief period, HBsAg production exactly matches antibody production, and the two coprecipitate such that neither free species is present in adequate concentration to be detectable. This problem can be circumvented either by serial measurements of HBsAg and anti-HBs, or by concurrent measurement of other antigens and antibodies, including HBeAg, anti-HBe, and anti-HBc (HBsAg is not reliable). During the window period, IgM anti-HBc may be the only marker of recent HBV infection, as it is in this nurse. If the nurse had been effectively vaccinated for hepatitis B, she would have had an elevated anti-HBs antibody level and no HBsAg present in the serum. Anti-HBc antibody would have been absent as well.
The antibody response to hepatitis B infection was appropriate in this person, which argues against immunocompromise. Carriers have elevated HBsAg and may have persistently elevated HBeAg (in approximately 10% of cases). IgG anti-HBc (not IgM) predominates in these chronic patients. Had she not been infected with hepatitis B at all, IgM anti-HBc would be absent.

Explanation:

CEA is a glycoprotein (200,000 daltons) that is found in the gastrointestinal mucosal cells and pancreatobiliary system secretions. It becomes elevated when breaks in the mucosal basement membrane occur due to tumor growth. Some other conditions can also cause elevations of CEA (e.g., cirrhosis, pancreatitis). The patient described above has colonic carcinoma, and the “apple core” lesion is the classic radiographic finding of this tumor. Although CEA is not used for screening because of the large number of false positives, it can be used to guide treatment in known cases. It returns to normal levels 30-45 days after tumor resection. If it begins to rise again, tumor recurrence is likely. AFP, or alpha-fetoprotein, is an alpha globulin (70,000 daltons) made by the liver and yolk sac of the human fetus. It is elevated with hepatocellular carcinoma and germ-cell neoplasms. It is not particularly specific. hCG, or human chorionic gonadotropin, is a glycoprotein secreted by trophoblastic epithelium of the placenta. It is useful (sensitive and specific) for germ-cell tumors of the testis and ovary. LDH, or lactate dehydrogenase, is avert nonspecific test that can be elevated in many conditions, including malignancy. PR, or progesterone receptor, is an immunohistochemical marker used when evaluating breast cancers.

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:

Embryonal carcinomas occur most commonly in the 20-30 age group and are more aggressive than seminomas. These tumors present with testicular enlargement, and 30% have metastasized at the time of diagnosis. Serum AFP is usually elevated. They are less radiosensitive than seminomas. Interstitial (Leydig) cell tumors can produce androgens, estrogens, or corticosteroids. In children, they often present with masculinization or feminization. In adults, they often present with gynecomastia. Microscopically, tumor cells resemble normal Leydig cells with round nuclei, eosinophilic cytoplasm, and lipid granules. Approximately half the tumors contain cigar-shaped crystalloids of Reinke. Seminomas occur most commonly in the fourth decade of life. Microscopic exam reveals sheets of uniform polyhedral cells divided by fibrous septa of connective tissue; lymphocytes and multinucleated giant cells may also be present. These tumors are highly radiosensitive. 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

Explanation:

This patient has developed malignant hypertension, a syndrome of end organ damage associated with long standing hypertension, usually occurring with blood pressures greater than 200/140 mm Hg. Severe elevations of blood pressure are frequently associated with hyperplastic arteriolitis (truly an arteriolosclerosis), typified by concentric, laminated smooth muscle proliferation narrowing the arteriolar lumen (onion skinning). Necrotizing arteriolitis, characterized by fibrinoid degeneration and acute inflammation in the arteriolar wall, may also be seen. Berry aneurysms arise at points of weakness in the arterial media, especially branch points in the circle of Willis. Although hypertension may play a role in atherosclerosis and the development of dissecting aortic aneurysms, berry aneurysms are believed to be congenital. Granulomatous arteries are typical of several large and medium vessel diseases, especially giant cell arteritis, Takayasu arteritis, and Wegener granulomatosis. It is identified histologically with mural inflammation with clusters of macrophages, often containing multinucleated giant cells. The arteriolar inflammation in malignant hypertension involves neutrophils, not granulomata. Phlebosclerosis is the characteristic change in varicose veins, in which dilated and tortuous veins show elastic degeneration and calcifications in the venous media. Thromboangiitis obliterans, also known as Buerger disease, is a disease of cigarette smokers. It is characterized by segmental vascular occlusion with luminal thrombus formation and microabscesses within small to medium-sized arteries and veins in the extremities.

Explanation:

This question illustrates an important strategy: knowing what you´re looking for before you consider the answer choices. If you thought about the answer before considering the choices, this question was very straightforward and simple. If, on the other hand, you considered each answer choice in turn, you no doubt got pretty confused and wasted a lot of precious test time.
The first thing to remember is that nephrotic syndrome is defined as proteinuria (>3.5 g/day) with concurrent hypoalbuminemia and hyperlipidemia. The loss of protein in the urine results in a decreased oncotic pressure in the vascular space. This decrease in capillary oncotic pressure promotes movement of fluid into the interstitium and the development of edema. This is also the cause of edema in patients with liver disease. Decreased interstitial oncotic pressure would actually promote the movement of fluid into the vasculature; it would not lead to edema. The same thing would occur with decreased capillary hydrostatic forces. Although decreased interstitial hydrostatic pressure would lead to edema, it is not the mechanism of action in nephrotic syndrome. Although increased capillary hydrostatic pressure does lead to edema, it is not the mechanism at work in nephrotic syndrome. It is, however, the mechanism of edema in the setting of both congestive heart failure (increased capillary hydrostatic pressure due to inefficient pumping of the heart, leading to pooling) and glomerulonephritis (increased intravascular volume due to inefficient excretion by the kidney).

Explanation:

Explanation:

Diabetic peripheral neuropathy usually goes in parallel with retinopathy and nephropathy. It is also slowly progressive and affects mainly spinothalamic pathway. Alcohol induced peripheral neuropathy is also slowly progressive and affects mainly spinothalamic pathway. Vitamin B12 deficiency usually causes a more rapidly progressive neuropathy with dorsal column involvement (joint position and vibration involvement with sensory ataxia and pseudoathetosis of upper limbs).

Explanation:

In the normal person, factor V functions as a cofactor to allow factor X to generate the active form of an enzyme called thrombin. Thrombin in turn cleaves fibrinogen to fibrin, which polymerizes to form the dense meshwork that makes up the majority of a clot. Activated protein C (aPC) is a natural anticoagulant that acts to limit the extent of clotting by cleaving and degrading factor V. Factor V Leiden is an autosomal dominant condition in which the coagulation factor cannot be destroyed by aPC. Mutation of the gene encoding factor Va single nucleotide substitution of adenine for guaninechanges the protein´s 506th amino acid from arginine to glutamine. Since this amino acid is normally the cleavage site for aPC, the mutation prevents efficient inactivation of factor V. When factor V remains active, it facilitates overproduction of thrombin leading to excess fibrin generation and excess clotting.

Explanation:

Vitamin D resistant rickets = X-linked dominant.
No linkage has been established for a particular gene in manic depressive disorder.

Explanation:

Liddle´s syndrome is typically associated with hypokalaemic hypertension and low renin and aldosterone concentrations – the so- called pseudo-hyperaldosteronism. Bartter´s syndrome is associated with hypokalaemia, though hypertension is not a feature.
In type IV RTA, there is a hyporeninaemichypoaldosteronism, which may also be produced with diabetic nephropathy, hence hyperkalaemia is more typical.

Explanation:

Studies show that over 90% of vegans (those who ate the strictest vegetarian diet, which shuns all animal products, including milk and eggs) had vitamin B12 deficiency. Approximately 65% of vegetarians (diets that included milk and eggs) were also deficient. Only 5% of those who consumed meats had vitamin B12 deficiency. B12 is not found in any plant food other than fortified cereals. It is, however, abundant in many meats and fish, and in smaller amounts in milk and eggs. This makes it difficult for people following a strict vegetarian diet to get the necessary amount of vitamin B12. Vitamin B12 deficiency leads to anemia. Symptoms of vitamin B12 deficiency, which usually come on gradually, include fatigue, weakness, nausea, and constipation. Long-term and severe vitamin B12 deficiency can lead to nerve changes such as numbness, tingling in the hands and feet, balance and memory problems, and depression

Explanation:

This patient has an acute episode of pancreatitis, which can be caused by alcohol, gallstones, blunt abdominal trauma, and medications, such as Lasix, DDI, and chemotherapy and it also has a heritable factor. Pancreatic cancer usually presents as asymptomatic jaundice, weight loss, and depression. The lipase level is not usually elevated in pancreatic cancer.

Explanation:

Emergency splenectomy used to be a common form of therapy for TTR but has been supplanted by other modalities, such as exchange transfusion. All of the other statements are true.

Explanation:

SLE can be associated with normocytic normochromic anemia (chronic inflammation) or microcytic hypochromic anemia (blood loss). The other entities are associated with macrocytosis. Mild macrocytosis is a common finding associated with rapid blood restoration or production compensating rapid turnover, since in general, “fresh” or newly-produced red cells (reticulocytes) are larger than the mean (average) size, due to slow shrinkage of normal cells over a normal red cell circulating lifetime.

Explanation:

The structures are psammoma bodies, which are thought to form around single necrotic cells that serve as a nidus for crystallization of calcium salts. While psammoma bodies are commonly discussed in pathology courses and tests because of their distinctive appearance, they are actually relatively uncommon. They are found most commonly in the four tumors i.e. papillary carcinoma of the thyroid; serous papillary cystadenocarcinoma of the ovary (which is present in this patient); meningioma and malignant mesothelioma. Neoplasms of the colon, seminal vesicles, spleen and stomach do not typically contain psammoma bodies

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:

Explanation:

Medullary thyroid carcinoma is not associated with multiple endocrine neoplasia syndrome type I, but is associated with type II. The other choices are all associated with type I.

Explanation:

Hepatitis D, also known as the delta virus, is a defective RNA virus, which requires the assistance of either hepatitis B or other hepadnaviruses for its replication and expression. In areas of high prevalence, transmission is person to person. In areas of low prevalence, transmission is typically among groups with exposure either to blood products or contaminated needles. Due to its reliance on hepatitis B, the duration of infection of hepatitis D parallels that of hepatitis B. Genomic heterogeneity among hepatitis D isolates has no clinical or pathologic implications. Concomitant infection with hepatitis B and D does not increase the probability of chronic hepatitis, but does increase the likelihood of fulminant hepatic failure as compared to those persons with hepatitis B infection alone.

Explanation:

Aspirin, through its effects on arachidonic acid metabolism, is thought to protect against colon cancer. Dietary factors have been extensively studied in carcinoma of the colon. An association between diets high in animal fat (saturated fats) has been suggested by several, but not all, studies. Based on studies of the South African Bantu, diets high in fiber were postulated to decrease the risk of colon cancer. This theory has not been definitively proven. In approximately 5-10% of cases, colon carcinomas develop at a site distal to the ureteral implant. Inflammatory bowel disease, particularly ulcerative colitis, predisposes to the development of colon carcinoma, especially in persons with the disease longer than 25 yearss.

Explanation:

All of the clinical findings point to the diagnosis of Buerger´s disease. Buerger´s disease, or thromboangitis obliterans, is a disease of smokers in their middle age. It typically affects mediumsized arteries and causes gangrene, ulcerations, and pain of the extremities, which typically house these arteries.

Explanation:

Explanation:

Acne has not been shown to be a risk factor in basal cell or squamous cell skin cancer. Individuals with fair complexions and blond hair are more prone to sunburns and subsequent skin cancer. This is thought to be due to less protection from sunburn due to a lower quantity of melanin pigment in the skin. Chronic UV exposure from the sun is a risk factor for skin cancer. Previous bums or scars are a predisposing factor for skin cancer (called scar carcinomas). Exposure to previous ionizing radiation or inorganic arsenic can be a risk factor for skin cancer.

Explanation:

Anaerobic bacteria derived from the oral flora in the clinical setting of periodontal disease are the most common isolates from lung abscesses. Single lung abscesses are the most common pattern, with the superior segment of a lower lobe or the posterior segment of an upper lobe being affected most often. Aspergillus fumigatus presents in the lung as hemorrhagic infarctions, aspergillomas (fungus balls) in cavitary tuberculosis cavities, or as allergic bronchopulmonary aspergillosis. Entamoeba histolyica is associated with pulmonary abscesses as an extension of a liver abscess across the diaphragm. Staphylococcus aureus usually presents as multiple lung lesions in non contiguous sites since the spread is embolic. The source of the infection is usually tricuspid endocarditis in IV drug abusers. Streptococcus pyogenes typically produces a bronchopneumonia pattern following an upper respiratory infection.

Explanation:

Endemic goiter, such as in this patient, is due to dietary iodine deficiency. This disorder is common worldwide in mountainous areas (where fish are not available). Frank symptoms of hypothyroidism may or may not be present, possibly because of the increased synthesis of the more potent triiodothyronine (T3) at the expense of thyroxine (T4). Copper deficiency can cause anemia, neutropenia, hypotonia, psychomotor retardation, osteoporosis, depigmentation of hair and glucose intolerance. Iron deficiency can cause anemia, cognitive dysfunction, impaired immunity, impaired thermoregulation, and reduced levels of physical activity. Selenium deficiency can cause congestive cardiomyopathy and skeletal muscle degeneration. Zinc deficiency causes rash and growth retardation, and impairments of immunity, wound healing, mentation, sexual function, and night vision.

Explanation:

This patient´s symptoms are typical for acromegaly, resulting from excess growth hormone (GH) effects in a post-pubertal adult. GH is secreted by anterior pituitary somatotroph cells in response to the hypothalamic secretion of growth hormone releasing hormone (GHRH). The modest suppression of GHRH in this patient is the result of excess negative feedback by GH secreted by the tumor. GHRH receptors are G-protein coupled receptors (GPCR) that activate G a, and transduce their signals by activating adenylate cyclase and increasing intracellular cAMP. A mutation preventing hydrolysis of GTP by Ga will cause excess receptor mediated signaling to the pituitary cells, resulting in proliferation and excess GH secretion. Options A and B are incorrect because a hepatic tumor might secrete IGF-1 but it would be in response to GH receptor stimulation. The growth effects of GH, including those seen with acromegaly, are mediated by IGF-1 and IGF-1 is secreted by the liver. But for a hepatic tumor to secrete IGF-1 in response to a mutation in a receptor signal transduction pathway, the mutation would need to be in the cytoplasmic tyrosine kinase transduction pathway of the GH receptor. Option C is incorrect because somatostatin inhibits GH release, it does not stimulate it. Option D is incorrect for the reasons discussed for the correct answer E.

Explanation:

Generalized transduction is the process by which a phage (bacterial virus) with a lyric life cycle can mistakenly incorporate pieces of the genomic DNA of a bacterium into its capsid and transfer that trait to a new bacterium it infects. The virus “delivers” the bacterial DNA from one bacterium to another, and the newly transferred DNA must be stabilized by the process of homologous recombination. In this way, DNA that had encoded a mutant penicillin binding protein from the chromosome of the penicillin resistant strain was accidentally picked up by the lyric phage and delivered to the penicillin sensitive bacteria. Those that successfully incorporated the mutant DNA were transduced to become penicillin-resistant. Mobilization of transposons is a process of movement of segments of mobile DNA within a bacterial cell. Transposons require no presence of virus and do not mediate the transfer of traits from one bacterium to another. Transposons can only be moved from cell to cell if the DNA they inhabit is transferred by conjugation, transformation, or transduction. Site specific recombination is the process by which circular, foreign DNA molecules can be joined into the chromosome of the bacterial cell. It is a requirement of the process of specialized transduction, but does not occur in generalized transduction, as described in this question stem. Specialized transduction is the process by which a phage with a temperate life cycle accidentally carries a portion of the bacterial genome with it as it excises its DNA from the chromosome prior to leaving the cell. This accidentally excised bacterial DNA can then be delivered to another bacterium that the specialized transducing phage infects. In this case, the experiment stipulates that a lytic, not a temperate phage is added; so specialized transduction is not a possibility. Transformation is the process by which free DNA can be taken up and incorporated by bacteria competent to do so. In this experiment, free DNA is not mentioned, and addition of a phage is mentioned, so the process has to be either specialized or generalized transduction.

Explanation:

The patient described probably has systemic lupus erythematosus (SLE), which often presents with fatigue, malaise, fever, gastrointestinal symptoms, arthralgias, and myalgias. Hematologic abnormalities include anemia, leukopenia, lymphocytopenia, and thrombocytopenia. A circulating anticoagulant may prolong the activated partial thromboplastin time (APTT). Cutaneous manifestations include a malar rash and a generalized maculopapular eruption, both of which are photosensitive. Antibodies to the Smith antigen (core proteins of small ribonucleoproteins found in the nucleus) are present in only 20% to 30% of patients with SLE, but are quite specific for the disease, occurring only rarely in other autoimmune diseases. Anti-centromere antibody is specific for the CREST (Calcinosis, Raynaud syndrome, Esophageal dysfunction, Sclerodactyly, and Telangiectasia) variant of progressive systemic sclerosis (scleroderma). Rheumatoid factor is actually an autoantibody directed against the Fc portion of the IgG molecule. It is found in more than two thirds of patients with rheumatoid arthritis. Around 95% of patients with SLE develop antinuclear antibodies (ANA), so this test is quite sensitive but not very specific for SLE. ANA occur in patients with other inflammatory disorders, autoimmune diseases, and viral diseases, as well as in a number of normal individuals. Antibodies to double stranded DNA are more specific for SLE but are not included as an answer choice. Anti-SS-A antigen refers to antibodies to certain ribonucleoproteins, which are fairly specific for Sjogren syndrome.

Explanation:

Sclerosing adenosis is a type of proliferative fibrocystic disease that is often seen with other variants of fibrocystic disease. It is a proliferation of small ducts and myoepithelial cells near the terminal duct lobular unit. It also is characterized by fibrosis that distorts the glands and lobules into a whorled pattern. When the sclerosing adenosis shows hyperplastic changes, atypical lobular hyperplasia, or a typical ductal hyperplasia, there is an increased risk for subsequent invasive breast cancer. Apocrine metaplasia is the term used to describe a transformation of ductal epithelial cells to eosinophilic cells resembling apocrine sweat gland epithelium. This is a benign, common, nonproliferative change that is not associated with increased cancer risk. A blue domed cyst of blood good is a fluid-filled cyst, sometimes up to 5 cm in size that appears blue grossly before it is incised. When incised, the fluid is serous and dark colored. These cysts are part of benign nonproliferative fibrocystic disease and do not carry increased cancer risk. Duct ectasia is characterized by a large dilated duct with inspissated material. It is associated with periductal inflammation and fibrosis of the large collecting ducts under the areola. It is common in elderly women, although the cause is not clear. There is no increased risk of cancer. Intraductal papilloma is a benign tumor that occurs in the large subareolar ducts. It is usually solitary and found in females who are middle aged to elderly. Clinically, it mimics cancer and may be associated with nipple discharge. It is covered with benign epithelium and attached to the duct by a fibrovascular stalk. A solitary lesion is not precancerous nor is it a risk for subsequent cancer.

Explanation:

The infant has a coarctation of the aorta. In this condition, the heart must pump against a higher than normal pressure. The left ventricle responds to this increased pressure load by undergoing hypertrophy, i.e. the wall thickness of the left ventricle increases as the myocytes enlarge. A similar process occurs when there is systemic hypertension. The increased blood pressure in the upper body (above the coarctation) also produces arterial hypertrophy, increasing the thickness of the vessel wall with decrease vessel wall thickness in arteries distal to the obstruction. The wall thickness of the abdominal aorta, femoral artery and other arteries below the constriction may decrease in response to the lower than normal pressures. Although one might predict a lower than normal blood flow to the kidneys leg muscles and other organs below the coarctation, if the body can compensate fully for the coarctation, blood flow will be normal in these low-pressure areas of the body.

Explanation:

The most common esophageal cancer is squamous cell in origin (although the incidence of adenocarcinoma is rising). Recall that the esophageal mucosa consists of stratified, nonkeratinized, squamous epithelium. Smoking and alcohol increase the risk for the development of esophageal squamous cell carcinoma. Suspect cancer when there are signs like rapid weight loss in a short period of time and symptoms such as dysphagia, hematemesis, and anorexia. Glandular epithelium is associated with adenocarcinoma, which is often associated with Barrett´s esophagus. This is not as common as squamous cell carcinoma, especially in smokers. A mesenchymal tumor is a sarcoma. A teratoma can be derived from all three germ layers, e.g., a dermoid cyst in the ovary. Transitional cell morphology is found in the urinary system and not in the esophagus, unless a urinary tract tumor was metastatic to that location.

Explanation:

The figure shown depicts a lymphocyte. Lymphocytosis is commonly associated with viral infections; therefore, you should have looked for a viral disease in the answer choices. Bronchiolitis in a 2 year old is most likely caused by respiratory syncytial virus. The rest of the diseases listed have bacterial etiologies. Cellulitis is a bacterial infection usually attributed to Staphylococcus or Streptococcus. Diphtheria is due to Corynebacterium diphtheriae. Epiglottitis in a 2 year old is most likely due to Haemophilus influenzae. Pertussis is caused by Bordetella pertussis.

Explanation:

This brief histologic description refers to brown tumors, which develop in association with hyperparathyroidism. These lesions result from repeated microfractures, with subsequent accumulation of hemosiderin laden macrophages and reactive osteodastic and fibroblastic proliferation. The brown color is due to hemosiderin deposition. Cushing syndrome is caused by excess of cortisol from endogenous or exogenous sources. Administration of glucocorticoids for therapeutic purposes is the most common form. Osteoporosis is the most significant effect of excess glucocorticoids. Graves disease is due to a hyperfunctioning thyroid, stimulated by autoantibodies to TSH receptors. Excessive production of thyroid hormone results in a complex clinical picture, in which bone changes are not seen. Hypoparathyroidism is an uncommon disorder most often due to surgical removal of the parathyroids. The most characteristic manifestation is tetany, resulting from decreased calcemia and consequent neuromuscular hyperexcitability. Hypothyroidism is a disorder of diminished thyroid function, most commonly due to previous Hashimoto thyroiditis. If hypothyroidism is present in utero, infancy, or early childhood, short stature, mental retardation, and other abnormalities develop (cretinism

Explanation:

Osteoarthritis is characterized by mechanical, rather than inflammatory, damage to the joint. The damage usually begins as multiple small fractures of the cartilage tips of the involved bones, which can lead to wearing down of the cartilage to expose the underlying bone. In long standing cases, the articular ends of the bones may develop a mushroom like or flattened deformation.
Synovial proliferation with pannus formation suggests chronic inflammatory joint disease, such as rheumatoid arthritis. White flecks in a joint suggest the crystals of gout or pseudogout. The presence of pus suggests an acute inflammatory (possibly infectious) etiology.