The correct answer is D.

The disease is hairy cell leukemia, which, unlike most forms of leukemia, is characterized by pancytopenia rather than increased numbers of circulating cells. This disease tends to affect older men and the characteristic cells (which are not always obviously "hairy") are positive for tartrate-resistant acid phosphatase (TRAP).
Associate Birbeck granules (choice A) with Langerhans cell histiocytosis (histiocytosis X).
Associate elevated leukocyte alkaline phosphatase (choice B) with myeloid metaplasia.
Associate Philadelphia chromosome (choice C) with chronic myeloid leukemia (and occasionally with acute lymphocytic leukemia).
Associate production of Bence-Jones proteins (choice E) with multiple myeloma.

The correct answer is B.

The border modification consists of cilia on the surface of pseudostratified columnar epithelium. Cilia are shorter than stereocilia and usually appear bent or wavy in sections. Kartagener's syndrome is one type of immotile cilia syndrome in which the dynein arms of microtubules are missing or defective. Thus, cilia cannot move properly and all functions associated with them are affected (mucous sweeping or ciliary elevator functioning, sperm motility, embryonic cell movement, etc.). The result is infertility, situs inversus, bronchiectasis and/or sinusitis.
Implantation (choice A) is not affected in patients with Kartagener's syndrome.

The fertilized ovum can still reach the endometrium and implantation can occur. Also, this is not a section of the uterine tube; the uterine tube has a simple columnar epithelium with peg cells (secretory) and ciliated cells.

The border modification consists of cilia, not microvilli and the specimen is not a section of the intestine, therefore malabsorption (choice C) is incorrect.

Both the small and large intestine have a simple columnar epithelium with microvilli. Microvilli are upright and irregular and resemble a "flat top" haircut across the top of cells.

Disaccharidases (choice D) are present in the cell membrane of microvilli. Deficiencies in digestion occur with the loss of microvilli.

The Correct Answer is D

The aetiology and risk factors of bowel cancer are yet to be fully understood.

Epidemiology suggests that men and women over 50 years of age are our main target group, especially those living in socially deprived, SIP and rural areas.

The prevalence of bowel cancer does not vary between social classes, however the stage of presentation does. People from lower social backgrounds tend to present much later.

The ‘high risk’ population include those with:

~Family history of bowel cancer

~Familial Adenomatous Polyposis (FAP)

~Hereditary Non-Polyposis Colon Cancer (HNPCC)

~History of Inflammatory Bowel Disease

The exact causes of colorectal cancer are not known. However, studies show that the following risk factors increase a person's chances of developing colorectal cancer:

• Age. Colorectal cancer is more likely to occur as people get older. This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens.
• Diet. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of bowel cancer.
• Polyps. Polyps are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer.

A rare, inherited condition, called familial adenomatous polyposis (FAP), causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to colorectal cancer.

• Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.
• Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
• Ulcerative colitis. Ulcerative colitis is a condition in which the lining of the colon becomes inflamed. Having this condition increases a person's chance of developing colorectal cancer.

The Correct answer is D

The malabsorption syndromes are those disorders of nutrition which result from disturbance of the normal process of

a) digestion and processing of nutrients into bioavailable form

b) absorption across functional surface of adequate length

c) transport to appropriate tissues

Malabsorption Syndrome = a constellation that includes diarrhea, steatorrhea, weight loss, and evidence of vitamin deficiencies.

The Correct Answer is B

Jaundice, also known as icterus, is a condition which is characterised by a yellowish discolouration of the skin and the whites of the eyes. It is a symptom or clinical sign, not a disease by itself. The yellow colouration is caused by an excess amount of the bile pigment known as bilirubin in the body. Normally, bilirubin is formed by the breakdown of haemoglobin during the destruction of worn-out red blood cells. The pigment is then excreted by the liver into the bile via the bile ducts.

Cause and Pathogenesis

Excess amounts of bilirubin in the body can be caused by the overproduction of bilirubin, the failure of the liver cells to metabolise or excrete the bilirubin produced, or a blockage of the bile ducts. Overproduction of bilirubin may be caused by the destruction of an unusually large number of red blood cells, which occurs in a condition known as haemolytic anaemia. In this condition the liver cannot excrete the bilirubin which is formed more rapidly. This may occur in diseases such as malaria, thalassemia, and haemolytic disease (due to destruction of the red blood cells) of the new-born . Often, mild jaundice occurs as a common and normal condition in new-born babies because at birth there is both a deficiency in the enzyme that helps to eliminate bilirubin and also an increased breakdown of red blood cells (RBC) in the body. In babies, the condition generally disappears within a few days after birth as the enzyme is formed in the body. Sometimes, deficiency of this enzyme can also cause jaundice in adults. Jaundice may also result from various diseases or conditions that can affect the liver, such as hepatitis, cirrhosis, or cancer. A blockage of the bile ducts, may cause jaundice. The ducts may be blocked by various factors including inflammation and infection (cholangitis), gallstones (cholelithiasis), or cancer of the pancreas or the common bile duct.

The clinical types of jaundice include haemolytic jaundice which is due to the breakdown of RBC; hepatocellular jaundice caused by hepatic pathology due to viruses, drugs, alcohol abuse, etc; and Cholestatic jaundice due to biliary tract obstruction.

There are various strains of hepatitis viruses including hepatitis A (HAV), hepatitis B (HBV), hepatitis C (HCV), hepatitis D (HDV), and hepatitis E (HEV). Viruses F and G also exist and may cause primary hepatitis. HAV is transmitted by contaminated food and water and by the faecal-oral route; HBV and HDV are transmitted by contact with bodily fluids, HCV by percutaneous exposure to blood, and HEV, by contaminated water and by the faecal-oral route. Hepatitis A is seen most often in children and young adults, but the incidence is rising among those who are HIV positive. Hepatitis B affects all age groups and is associated with blood transfusion. Hepatitis C accounts for most transfusion-related cases. It is seen in all age groups. Hepatitis D is seen in individuals who are susceptible to HBV or may be HBV carriers, such as haemophiliacs and IV drug users. The disease manifestation is severe in children. Hepatitis E is seen primarily among young adults in developing countries. It is most severe in pregnant women. Congenital non-haemolytic hyperbilirubinemia such as Gilbert's Syndrome also causes jaundice. Sometimes certain drugs such as chlorpromazine (an anti-psychotic drug) may inhibit bilirubin excretion by the liver, causing jaundice.

The correct answer is B.

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 (over 3.5 gm/day) with concurrent hypoalbuminemia and hyperlipidemia. The loss of protein in the urine results in a decreased oncotic pressure in the vascular space (decreased pc). 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 (pi; choice D) 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 (Pc; choice A).

While decreased interstitial hydrostatic pressure (Pi; choice C) would lead to edema, it is not the mechanism of action in nephrotic syndrome.

While increased capillary hydrostatic pressure (choice E) 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 congestive heart failure (increased capillary hydrostatic pressure due to inefficient pumping of the heart, leading to pooling) and in glomerulonephritis (increased intravascular volume due to inefficient excretion by the kidney).

Increased capillary oncotic pressure (choice F) would not lead to edema.

Increased interstitial hydrostatic pressure (choice G) would not lead to edema.

Increased interstitial oncotic pressure (choice H) would cause edema, but not in the setting of nephrotic syndrome. Instead, this is the mechanism of edema (typically localized) in the setting of burns and inflammation (increased capillary permeability allows protein to leak into interstitium and increase oncotic pressure).

The correct answer is D.

Many people who request physician-assisted suicide have one of two conditions present: either a poorly controlled painful condition or severe depression. If the painful condition is adequately treated or the depression is brought under good medical control, the request for physician assistance in terminating the situation is typically withdrawn. It is important to note that bringing these conditions under control requires the intervention of caregivers who are specifically trained in the management of these two conditions; primary care physicians usually are not adequately trained to address these difficult presentations.

While patients who are diagnosed as bipolar disorder (choice A), borderline personality disorder (choice B), and schizophrenic disorder (choice E) often make suicide attempts (and frequently complete those attempts), they do not generally ask their physician for assistance in the suicide.
Persons with factitious disorder (choice C) are seeking primary gain, often for dependency needs, and are seeking to enter the "sick role" not the "dead role.

The correct answer is B.

First, eliminate all answers in which Drug X does not produce an increase in blood pressure (BP).

Choice A should be eliminated because acetylcholine stimulates the noninnervated muscarinic (M3) receptors that are located on endothelial cells of the vasculature. Stimulation of these receptors releases endothelial-derived relaxing factor (EDRF; nitric oxide), which produces a relaxation of the neighboring smooth muscle cells, leading to a decrease in BP.

Choice C should be eliminated because isoproterenol (a nonspecific beta agonist) decreases BP by stimulating beta-2 receptors in the vasculature.

Epinephrine, norepinephrine, and phenylephrine all increase BP, so the remaining answers must be eliminated by examining the effects of Drug Y on Drug X.

Start with choice B: Epinephrine is an agonist at alpha-1, alpha-2, beta-1, and beta-2 receptors; phentolamine is an antagonist at alpha-1 and alpha-2 receptors. Therefore, after the administration of phentolamine, epinephrine can stimulate only beta receptors, which would produce a decrease in BP. Epinephrine is now acting like isoproterenol. This is called epinephrine reversal (the name stems from the fact that epinephrine originally increases BP and then produces the opposite effect after phentolamine administration). Therefore, choice B is correct.


Choice D: Norepinephrine is an agonist at alpha-1, alpha-2, and beta-1 receptors; propranolol is a nonselective beta antagonist. After administration of propranolol, norepinephrine can stimulate only alpha receptors, which will still cause vasoconstriction (primarily via alpha-1 stimulation in the vasculature) and therefore increase BP.


Choice E: Phenylephrine is an alpha-1 agonist; hexamethonium is a nicotinic ganglionic blocker. Hexamethonium administration would be predicted to eliminate the baroreceptor response after the second phenylephrine administration by blocking the peripheral ganglia. However, phenylephrine will still reach the alpha-1 receptors on the vasculature to produce an increase in blood pressure.

The correct answer is A.

Bilirubin is a degradative product of hemoglobin metabolism. Bilirubin (pigment) stones are specifically associated with excessive bilirubin production in hemolytic anemias, including sickle cell anemia. Bilirubin stones can also be seen in hepatic cirrhosis and liver fluke infestation.

Calcium oxalate stones (choice B) and cystine stones (choice E) are found in the kidney, rather than the gallbladder.

Pure cholesterol stones (choice C) are less common than mixed gallstones, but have the same risk factors, including obesity and multiple pregnancies.

Mixed stones (choice D) are the common "garden variety" gallstones, found especially in obese, middle aged patients, with a female predominance.

The correct answer is D.

Duchenne muscular dystrophy (DMD) is a lethal, X-linked recessive disease affecting approximately 1 in 3300 live male births. The disease becomes symptomatic in early childhood. Inability to walk occurs by the end of the first decade, and death usually occurs by the second decade. Nearly all patients show the complete absence of the protein dystrophin, which is abundant in skeletal and cardiac muscle. The dystrophin gene (or DMD gene), located at Xp21, is approximately 2300 Kb in size, making it one of the largest known genes of any species. It contains 24 regions of 109 amino acids that are similar but not identical repeats of each other. In women, the similarity of these sequences can lead to the misalignment of homologous material at meiotic synapsis. In association with a recombination event, this misalignment gives rise to frameshift mutations, leading to an untranslatable mRNA. This series of events occurs at an extremely high rate of about 1 in 10,000. In fact, one third of DMD cases in each generation arise from this mechanism.

Diseases such as fragile X syndrome and Huntington disease are caused by the expansion of a trinucleotide repeat (choice A).

Infidelity (choice B) is not a plausible explanation for the child because the trait is an X-linked recessive condition. A male child must receive the DMD trait on the maternal X chromosome. The father of the child contributes only a Y chromosome, and the history stated that the mother had no family history of the disorder.

DMD in a patient with no family history is not generally due to a point mutation in the dystrophin gene (choice C).

Rare cases of DMD in females have been caused by an X chromosome-autosome translocation (choice E) with the breakpoint on the X chromosome within the DMD gene. Because of the translocation, only the cells in which the normal X chromosome is inactivated survive in the female zygote. This gives rise to a female who is heterozygous for the DMD gene but phenotypically expresses the disease.

The correct answer is B.

C3b is the most critical molecule in both the classical and alternative complement pathways. C3, the most abundant protein of all the complement proteins, is cleaved into C3a and C3b. C3b attaches to bacterial surfaces for opsonization by phagocytes. C3a binds to mast cells and basophils, activating them and producing histamine release.

C1q (choice A) is a complement component in the classical pathway. It binds to the constant heavy domain of an IgG molecule that has reacted with the bacterial surface epitope. C1q is not involved in opsonization as it simply functions as an enzyme in the early complement cascade.

C5 (choice C) is a protein, that once split into C5b, initiates the assembly of the membrane attack complex. This complex consists of C5b, C6, C7, C8, and polymerization of C9, and is responsible for lysis of the bacteria. C5a is a strong chemotactic molecule.

This fragment is the result of C5 being split by the C5 convertases of both pathways. This C5a (choice D) is a strong chemotactic factor for neutrophils and results in stimulating the inflammatory response.

Factor B (choice E) is an activator protein of the alternative pathway. It combines with C3b to form C3bBb. This C3bBb is the C3 convertase of the alternative pathway.

The correct answer is C.


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 (even in the United States), 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 (choice A) usually infects the large intestine and/or liver.

Escherichia coli (choice B) is a bacterial cause of diarrhea.

Naegleria fowleri (choice D) causes meningoencephalitis.

Trichomonas vaginalis (choice E) causes vaginitis.

The correct answer is E.

The findings described are those of tabes dorsalis, a form of tertiary syphilis caused by Treponema pallidum. Tabes dorsalis, and other forms of tertiary syphilis, are now uncommon in this country, possibly because the common use of antibiotics may "treat" many unsuspected cases of syphilis.
Haemophilus influenzae (choice A) and Neisseria meningitidis (choice D) can cause meningitis.
Neisseria gonorrhoeae (choice C) causes gonorrhea, which usually does not involve the CNS.
Herpes simplex I (choice B) can cause an encephalitis that typically involves the frontal and temporal lobes.

The correct answer is E.

Urinary tract infections are the most common bacterial infections encountered during pregnancy, and Escherichia coli is the most commonly isolated organism. 70% of cases in the U.S. are caused by P pili-positive strains.
Bundle-forming pili (choice A) are found in enteroaggregative E. coli (EAEC).
GVVPQ fimbriae (choice B) are found in EAEC.
Heat labile toxins (choice C) are pathogenic factors in enterotoxic strains (ETEC).
Heat stable toxins (choice D) are pathogenic factors in ETEC or EAEC.
Type 1 pili (choice F) are a major pathogenic factor in ETEC.

The correct answer is A.

The spinal cord arises from the caudal end of the neural tube. During development, an alar and a basal plate is formed, separated by a longitudinal groove called the sulcus limitans (choice E).

The alar plate forms the dorsal (posterior) part of the spinal cord and becomes the sensory or afferent portion of the cord. The basal plate (choice B) is the ventral (anterior) part of the cord, and becomes the motor, or efferent, portion of the spinal cord, and therefore would contain anterior horn cells.

The neural crest (choice C) develops into multipolar ganglion cells of autonomic ganglia, pseudounipolar cells of spinal and cranial nerve ganglia, leptomeningeal cells, Schwann cells, melanocytes, chromaffin cells of the adrenal medulla, and odontoblasts.

The brain forms from the rostral end of the neural tube (choice D).

The correct answer is C.

While the third-week embryo is a primitive trilaminar plate, in the fourth week, the heart begins to form and begins beating almost immediately. Hematopoiesis occurs in the yolk sac, and a primitive circulatory system connects the capillary plexuses of the yolk sac and chorion to the embryo. Partitioning of the atrium also begins in the fourth week. During the fifth week, cardiac septa form and the atrioventricular (AV) cushions fuse. By the sixth week, the heart is close to fully formed. This early sequence for the heart explains why it is so difficult to try to prevent congenital malformations of the cardiovascular system from occurring, since the mother of a 6-week-old fetus is only about 8 weeks from her last menstrual period, and may have assumed that she just "missed a period" (a very common phenomenon) for reasons other than pregnancy

The correct answer is C.


The muscularis of the upper third of the esophagus (choice E) is composed entirely of striated muscle. The middle third (choice C) contains both striated and smooth muscle. The lower third (choice B) and lower esophageal sphincter (choice A) contain only smooth muscle. There is no such thing as the upper esophageal sphincter (choice D).

The correct answer is D.

The cells of the anterior pituitary can be classified as chromophils (love dyes) or chromophobes (do not stain with dyes). The chromophils can be further divided into acidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils include the somatotropes, which secrete growth hormone, and the mammotropes, which secrete prolactin.

The basophils include the corticotropes, which secrete ACTH (choice A), the gonadotropes, which secrete FSH and LH (choices B and C), and the thyrotropes, which secrete TSH (choice E).

The correct answer is E.

Mastication is a complex process involving alternating elevation, depression, forward movement, and backward movement of the lower jaw. The backward movement step is accomplished by the posterior fibers of the temporalis muscle.

The digastric (choice A) helps to depress the lower jaw during chewing.

The lateral pterygoid (choice B) helps to move the lower jaw forward during chewing.

The medial pterygoid (choice C) helps to elevate the lower jaw during chewing.

The mylohyoid (choice D) helps to depress the lower jaw during chewing.

The correct answer is A.

Flumazenil is a benzodiazepine antagonist and has been approved to hasten the recovery from benzodiazepines used in anesthetic and diagnostic settings and to reverse the CNS depressant effects following an overdose with benzodiazepines. Flumazenil can only be used for benzodiazepines and is not useful to reverse the effects of other CNS depressants such as barbiturates and ethanol.

Glucagon (choice B) is an antidote for beta-blocker overdose.

Naloxone (choice C), an opioid receptor antagonist, is an antidote for opioid overdose.

Nitrite (choice D), or sodium nitrite, is an antidote for cyanide poisoning.

Protamine (choice E) is an antidote for heparin overdose.

The correct answer is E.

The thyroglossal duct develops as an evagination of the floor of the pharynx in the region where the tongue develops. The adult foramen cecum of the tongue marks the site of this evagination. The distal end of this duct normally forms the thyroid gland; the proximal part of the duct normally degenerates. Failure of a part of the duct to degenerate may lead to a thyroglossal duct cyst or median cervical cyst, as seen in this patient.

The first pharyngeal cleft (choice A) forms the external ear canal. This cleft normally remains patent.

The first pharyngeal pouch (choice B) forms the middle ear cavity and the auditory tube. This pouch normally remains patent.

The second pharyngeal cleft (choice C) normally does not remain patent. It is typically covered over by the overgrowth of the second pharyngeal arch. If part of this pouch does remain patent, it may form a lateral cervical cyst, which is seen on the lateral side of the neck along the posterior border of the sternocleidomastoid muscle.

The second pharyngeal pouch (choice D) forms the tonsillar fossa of the pharynx. The pharyngeal mucosa in this area arises from the endoderm of the pouch. Ingrowth of mesoderm cells results in the formation of the palatine tonsil.

The correct answer is A.

The cavernous sinuses are located on either side of the body of the sphenoid bone, and become a potential route of infection because they receive blood both from the face (via the ophthalmic veins and sphenoparietal sinus) and some of the cerebral veins. The spread of infection, especially by Mucor sp., into the cavernous sinus, can produce either CNS infection or cavernous sinus thrombosis, both of which are potentially fatal.

The route from the face to the brain is not arterial (choices B and C).

The superior sagittal sinus (choice D) is located in the falx cerebri, and drains venous blood from the brain to other dural sinuses, from which it eventually drains into the jugular vein.

Zygomycosis does not reach the brain by way of the superior sagittal sinus.

The superior vena cava (choice E) drains blood from the upper part of the body into the heart.

The correct answer is B.

The diagnosis of chronic bronchitis requires the presence of chronic productive cough over at least 3 months of the year for 2 successive years. The symptoms in this patient (green productive sputum, fever) suggest that he has an acute infection superimposed on chronic bronchitis (history of cigarette smoking, history of excessive mucus production over many years). Histologically, the mucus-producing glands in the bronchi would show hyperplasia and hypertrophy and extend to a greater depth in the bronchial wall, resulting in a higher Reid index (ratio of thickness of mucus gland to thickness of bronchial wall).

Although the patient is a smoker and is at increased risk for bronchogenic carcinoma (choice A), this is unlikely to be the cause of his symptoms. Hemoptysis and weight loss might also be present if he had cancer.

Cystic fibrosis (choice C) presents earlier in life and may be associated with severe production of mucus, especially if bronchiectasis supervenes. The age of the patient and the relative late onset of disease preclude this diagnosis.

This patient may also have emphysema (choice D), as chronic bronchitis and emphysema are often coexistent. However, although pure emphysema might cause dyspnea, it would not be associated with a fever or a productive cough.

Pulmonary tuberculosis (choice E) would typically present with a history of hemoptysis rather than abundant green sputum. Weight loss, night anorexia, malaise, and weakness may also be present.

The correct answer is D.

The key symptom is hyperventilation. Hyperventilation results in hypocapnia, alkalosis, increased cerebrovascular resistance, and decreased cerebral blood flow. Carbon dioxide plays an important role in the control of cerebral blood flow. An increase in arterial PCO2 dilates blood vessels in the brain and a decrease in PCO2 causes vasoconstriction. The anxious, hyperventilating woman is "blowing off" carbon dioxide, which lowers her arterial PCO2.

This decrease in PCO2 has caused the cerebrovascular resistance (choice E) to increase, thereby decreasing cerebral blood flow. The decrease in cerebral blood flow has caused the woman to feel faint and to have blurred vision. Other symptoms commonly associated with the hyperventilation of anxiety states are feelings of tightness in the chest and a sense of suffocation.

Hyperventilation increases the arterial oxygen content (choice A) and PO2 (choice B) in a normal person.

A decrease in arterial PCO2 causes the arterial pH (choice C) to increase, i.e., the patient becomes alkalotic.

The correct answer is B.

The most probable etiology of bacterial endocarditis involving the tricuspid valve is illicit intravenous drug use, which can introduce skin organisms into the venous system that then attack the tricuspid valve. Staphylococcus aureus accounts for between 60% and 90% of cases of endocarditis in intravenous drug users.

The endocarditis associated with congenital heart disease (choice A) typically involves either damaged valves or atrial or ventricular septal defects. The tricuspid valve is not particularly vulnerable.

Rheumatic fever (choice C) most commonly damages the mitral and aortic valves, and tricuspid damage is usually less severe and seen only when the mitral and aortic valves are heavily involved. Consequently, secondary bacterial endocarditis involving only the tricuspid valve in a patient with a history of rheumatic fever would be unusual.

Rheumatoid arthritis (choice D) is not associated with bacterial endocarditis.

Systemic lupus erythematosus (choice E) can produce small, aseptic vegetations on valves, but is not associated with bacterial endocarditis

The correct answer is A.

This man has a respiratory acidosis. Overdose with drugs that suppress ventilation (e.g., heroin, morphine, barbiturates, methaqualone, and "sleeping pills") often causes hypercapnia. In patients with an intact renal response, the respiratory acidosis causes a compensatory rise in plasma HCO3-, which lessens the fall in pH. However, the renal response requires several days to develop fully. The plasma HCO3- of 26 mEq/L (normal: 22-28 mEq/L) for this man is typical of acute respiratory acidosis with little or no renal compensation.

Choice B reflects metabolic acidosis.

Choice C is normal.

Choice D reflects respiratory alkalosis.

Choice E reflects metabolic alkalosis.

The correct Answer is B

The neurological complications result from one point mutation that causes vasculopathy of both large and small vessels. Anemia and the resultant cerebral hyperemia produce conditions of hemodynamic insufficiency. Sickled cells adhere to the endothelium, contributing to a cascade of activated inflammatory cells and clotting factors, which result in a nidus for thrombus formation. Because the cerebrovascular reserve becomes exhausted, the capacity for compensatory cerebral mechanisms is severely limited. There is evidence of small-vessel sludging, and a relative deficiency of nitric oxide in these vessels further reduces compensatory vasodilatation. Both clinical strokes and silent infarcts occur, affecting motor and cognitive function.


Reference:
Sickle cell disease: the neurological complications. Ann Neurol. 2003 Jan;53(1):143; author reply 143-4. PMID: 12112099 [PubMed - indexed for MEDLINE]