USMLE STEP-1 PREPARATION                       PART-1COLLECTED BY Gankidi Raghavender                             Grreddy8...
ZAPOROZHYE STATE MEDICAL UNIVERSITY ,   UKRAINEAddisons disease Adrenal insufficiency can cause hyperpigmented skin   due ...
Diabetes mellitus Although DM causes polyuria and polydipsia, it cannot                 account for the patients other sym...
Clorothiazide This thiazide diuretic inhibits Na/CL cotransported in the                 early distal convoluted tubules. ...
difficulty with the facial muscles of both the upper and                lower face, we know that the lesion in cranial ner...
addition, PGIs are responsible for decreased bronchial and               vascular tones, as well as decreased platelet agg...
Frameshift mutation This type of mutation is caused by the addition or                deletion of a base pair, which chang...
leg (and possibly arm symptoms in milder forms). The face                is typically spared.Right anterior cerebral arter...
urinary tract infections, sepsis, and hot tub folliculitis.                 Pseudomonas grows in water and can withstand m...
coloration on MacConkey plates indicates lactose                fermentation.A great increase cardiac output and GFR Prazo...
Lyme disease Borrelia burgdorferi is a tick-borne spirochete that is               classically associated with erythema ch...
high fever, malaise, and myalgia. It can also be associated               with a lobar process on CXR.Pulmonary tuberculos...
against P. falcipartum. This drug is not used for                 prophylactic purposes.Eating undercooked beef is usually...
We will set you up for a mammogram today. There is no current indication for                 mammogram. Also, due to the d...
Hypoxanthine-guanine phosphoribosyl transferase Hypoxanthine-guanine               phosphoribosyl transferase (part of the...
condition can result from inhalation of car exhaust or an                 old gas heater that has just been started up on ...
involved in replication of highly repetitive sequences of                DNA.Antisocial personality disorder Patients with...
Change the antibiotic because it is unlikely to cover Streptococcus bovis                Vancomycin and gentamicin provide...
Prescribe a trial of ativan Night terrors are nightmares that are not recalled.Prescribe a trial of imiprimine Imiprimine ...
This is a dermatophyte infection of a microsporum species. Certain microsporum                 species, when hairs are inv...
Subhyaloid hemorrhage A subhyaloid hemorrhage is a hemorrhage in the               eye between the retina and vitreous bod...
gallbladder surgery, it is not the most common artery                damaged during dissection of that area.P. falciparum ...
jaundice of the skin during these periods. Gilberts                syndrome affects 3% to 7% of the population and is more...
Increased calcium, decreased phosphate, increased alkaline phosphatase A                patient with increased calcium, de...
Lysosomal storage Diseases such as Gaucher disease do not give the                clinical findings described here.An alph...
Somatostatin Somatostatin inhibits gallbladder contraction, pancreatic               fluid secretion, small-bowel fluid se...
Listeria and E. coli While Listeria and E. coli are common causes of                  meningitis in the newborn, answer A ...
eventually increases two to three months after infection.                around 8–12 weeks post-infectionNormal CD4 count ...
blocks the stimulation signal for proliferation in these cells                 and controls the rate of cell replication.A...
lesions below T12. Abdominal straining and compression,                called Credes maneuver, will often allow voiding.Th...
with a significant family history of diabetes mellitus on a                 medication that would further increase her ris...
During a busy day in the emergency room, a 37-year-old male presents                complaining of acute epigastric abdomi...
Gastritis Although patients with gastritis often present with epigastric                 pain and nausea, serum amylase an...
According to current thinking, which of the following is the first-line treatment for                 congestive heart fai...
Estradiol 20 days after menses If estradiol was given 20 days after menses,                 then the cycle would already b...
The patients tumor represents the malignant transformation of exocrine cells.                 Duct cells represent 4% of t...
Sanfilippos syndrome are all disorders due to faulty                 metabolism of dermatan sulfate and heparan sulfate.  ...
Aminoglycosides Block protein synthesis at the 30S ribosomal subunit, as                do the tetracyclines.Chloramphenic...
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21173685 fmge-mci-screening-test-study-material-part-1-by-gankidi-raghavender-reddy-mbbs-stu-zsmu-ukraine

  1. 1. USMLE STEP-1 PREPARATION PART-1COLLECTED BY Gankidi Raghavender Grreddy836@gmai l.com200 + Important exclusive points ➢ Mostly repeated in FMGE,PLAB,AIIMS,AIPGE ➢ Made easy to understand
  2. 2. ZAPOROZHYE STATE MEDICAL UNIVERSITY , UKRAINEAddisons disease Adrenal insufficiency can cause hyperpigmented skin due to an increase in melanocyte-stimulating hormone (MSH). Patients will have electrolyte imbalances due to aldosterone deficiency and experience severe reactions to minor illnesses due to cortisol deficiency. Diagnosis is confirmed using the ACTH stimulation test.Cushings syndrome Patients with Cushings syndrome will have characteristic features such as central obesity with a ‘buffalo hump’, moon facies, peripheral muscle wasting, purple striae, easy bruising, and psychiatric disorders. This disorder is due to glucocorticoid excess. Diagnosis is confirmed with the dexamethasone suppression test.
  3. 3. Diabetes mellitus Although DM causes polyuria and polydipsia, it cannot account for the patients other symptoms.Hemochromatosis This metabolic disorder, which is also known as ‘bronze diabetes’, is an autosomal recessive disorder resulting from increased absorption of iron from the GI tract. Iron accumulates in several organs, including the pancreas (causing diabetes), heart (causing cardiomyopathy), testicles (causing testicular atrophy), skin (causing increased pigmentation), and liver (causing cirrhosis). Treatment consists of regular phlebotomy and deferoxamine, an iron chelator.Wilsons disease This autosomal recessive disorder is caused by impaired copper excretion. Signs and symptoms include tremor, ataxia, dementia, and psychoses. The classic ophthalmic finding is Kayser-Fleischer rings (brown-pigmented rings at the edge of the cornea) from copper deposits. Treat with penicillamine, a copper chelator.Acetazolamide Acetazolamide is a carbonic anhydrase inhibitor. Members of this class of drugs are generally not used to treat hypertension, as the diuresis is self-limiting within two to three days. The mechanism of self-limiting diuresis is as follows: By inhibiting carbonic anhydrase in proximal convoluted tubules, acetazolamide causes increased urinary excretion of bicarbonate. As the body bicarbonate level decreases, excretion slows even with continued diuretic use, and the diuresis becomes self-limiting.Amiloride This potassium-sparing diuretic works in the late distal tubules and the cortical collecting ducts by inhibiting reabsorption of Na and secretion of K and H. It would be useful for treatment of hypertension, but it does not have any effect on reabsorption of calcium. Furosemide is a better option, as it would also help reabsorb calcium and, therefore, not make the patients osteoporosis worse.
  4. 4. Clorothiazide This thiazide diuretic inhibits Na/CL cotransported in the early distal convoluted tubules. It is useful for treatment of hypertension, especially in a patient with osteoporosis, as it increases calcium reabsorption from urine by an unknown mechanism.Furosemide Furosemide is a loop diuretic that works on the medullary ascending loop of Henle by inhibiting Na/K/2 CL cotransport that accounts for 20% to 25% of reabsorption of Na. Downstream sites cannot compensate for the sodium excretion, which makes these drugs very efficacious and useful for treatment of hypertension. Loop diuretics cause decreased reabsorption of calcium from urine, however, and they may worsen this patients osteoporosis condition. In fact, loop diuretics are often employed for treatment of hypercalcemia (as induced by malignancy, for example).Mannitol Mannitol is an osmotic diuretic. Most of the filtered solutes will be excreted in larger amounts unless they are actively reabsorbed. Osmotic diuretics are not indicated for treatment of hypertension, but may be used to decrease cerebral edema and intraocular pressure.Cavernous sinus This sinus contains cranial nerves III, IV, V, and VI as well as the internal carotid artery. Cranial nerves VII and VIII do not pass through here.Floor of the middle cranial fossa in the trigeminal dural cave The middle cranial fossa contains a number of structures that carry many important vessels and nerves, including the cranial nerves associated with ocular motility (III, IV, and VI) and sensation (V). However, this portion of the fossa does not contain any nerves that would explain the patients unilateral hearing loss.Internal auditory meatus This structure holds the facial and vestibulocochlear nerves (cranial nerves VII and VIII) as well as the labyrinthine artery. Because the patient has
  5. 5. difficulty with the facial muscles of both the upper and lower face, we know that the lesion in cranial nerve VII must be peripheral instead of central (in which only the lower portion would be involved). Cranial nerve VII also gives rise to the preganglionic parasympathetic fibers that will innervate the lacrimal gland, which forms tears. A lesion in cranial nerve VIII in this location also explains unilateral hearing loss.Jugular foramen This foramen transmits cranial nerves IX, X, and XI as well as a portion of the internal jugular artery. These structures are not responsible for the patients symptoms.Superior orbital fissure This fissure transmits cranial nerves associated with ocular motility (cranial nerves III, IV, and VI) as well as the ophthalmic nerves and veins. A lesion here would not explain the patients auditory symptoms or the lack of abnormalities in ocular motility.Leukotrienes production Aspirin, like NSAIDs and acetaminophen, blocks COX-1 and COX-2 enzymes in the arachidonic acid metabolism. However, the lipoxygenase enzyme pathway is not blocked, thus funneling most of the arachidonic acid through the lipoxygenase pathway that produces leukotrienes (LTB, LTC, LTD). LTs are responsible for increased bronchial tone (i.e., bronchospasm), causing the respiratory distress symptoms observed in this patient.Phospholipase A2 deficiency A deficiency in phospholipase A2 would mean that no arachidonic acid is produced. If there is a deficiency in arachidonic acid, then aspirin has no negative effect and would not cause respiratory distress.Prostacyclin production Prostacyclins are by-products of arachidonic acid metabolism via the COX enzyme pathway. Because aspirin blocks both COX-1 and COX-2, no PGIs will be produced. In
  6. 6. addition, PGIs are responsible for decreased bronchial and vascular tones, as well as decreased platelet aggregation.Prostaglandin production Prostaglandins are by-products of arachidonic acid metabolism via the COX enzyme pathway. Because aspirin blocks both COX-1 and COX-2, no PGE/PGF will be produced. Prostaglandins are responsible for decreased bronchial and vascular tones.Thromboxane production Thromboxane is a by-product of arachidonic acid metabolism via the COX enzyme pathway. Because aspirin blocks both COX-1 and COX-2, no TXA will be produced. TXA, however, can increase bronchial tone and result in bronchospasm, leading to respiratory distress.Acting out Acting out is the expression of unacceptable thoughts in actions. An example might be violent behavior toward an inanimate object.Denial A reality is avoided. This is a very common reaction to hearing any life-changing news.Displacement Unacceptable thoughts are placed on another person or object.Isolation Emotions are divorced from events. This response is often experienced after being a survivor of a plane crash, bombing, or cataclysmic fire.Rationalization Unacceptable thoughts are replaced by logical reasoning, explaining why something happened.
  7. 7. Frameshift mutation This type of mutation is caused by the addition or deletion of a base pair, which changes the reading frame. The resultant protein is usually nonfunctional.Large segment deletion mutation This type of mutation is usually due to an unequal crossover in meiosis. Alpha-thalassemia is an example.Missense mutation The patient has sickle cell anemia and is in a sickle cell crisis. This condition is caused by a point mutation in which glutamic acid is replaced with valine. The result is an unstable hemoglobin molecule.Nonsense mutation This type of mutation causes the insertion of a stop codon in the reading frame. The resultant protein is usually shorter and nonfunctional.Silent mutation In this mutation, the codon is changed but still specifies the same amino acid. There is no adverse reaction from this type of mutation.Left middle cerebral artery Blockage of this vessel would cause, among other effects, right-sided hemiplegia and sensory deficits mainly of the face and arms, a right visual field defect with inability to gaze to the right, and aphasia.Right middle cerebral artery Blockage of this vessel would cause, among other things, left-sided hemiplegia and sensory deficits mainly of the face and arms and left visual field neglect with inability to gaze to the left. In addition, there may be neglect of the left side.Left anterior cerebral artery This vessel supplies the medial aspects of the left hemisphere. Blockage may cause a weak, numb right
  8. 8. leg (and possibly arm symptoms in milder forms). The face is typically spared.Right anterior cerebral artery This vessel supplies the medial aspects of the right hemisphere. Blockage may cause a weak, numb left leg (and possibly arm symptoms in milder forms). The face is typically spared.Left posterior cerebral artery This lesion presents as a right-sided visual field deficit, alexia without agraphia (if the corpus callosum is spared), and possible defects in naming colors.Right posterior cerebral artery This lesion typically presents as a left-sided visual field deficit along with left-sided sensory loss if the thalamus is affected. There may also be left-sided neglect.Left posterior inferior cerebellar artery This lesion would cause infarction of the lateral medulla and inferior cerebellar surface, causing vertigo with vomiting, dysphagia, and dysarthria. In addition, there would be nystagmus looking toward the left, left–sided Horners syndrome, and loss of pinprick sensation on the left side of the face and on the right side of the trunk and extremities. This condition is also known as Wallenbergs syndrome.Right posterior inferior cerebellar artery This lesion would cause infarction of the lateral medulla and inferior cerebellar surface, causing vertigo with vomiting, dysphagia, and dysarthria. In addition, there would be nystagmus looking toward the right, right–sided Horners syndrome, and loss of pinprick sensation on the right side of the face and on the left side of the trunk and extremities. This condition is also known as Wallenbergs syndrome.Colorless colonies on MacConkey agar; oxidase positive; blue-green pigment on nutrient agar Pseudomonas aeruginosa causes pneumonia,
  9. 9. urinary tract infections, sepsis, and hot tub folliculitis. Pseudomonas grows in water and can withstand many detergents and disinfectants. Pyocyanin gene product gives purulent material a bluish hue, while pyoverdin is seen as yellow-green with ultraviolet light. Ultraviolet light may be used to assess cutaneous infection by Pseudomonas in burn patients. Pseudomonas does not ferment glucose.Colorless colonies on MacConkey agar; urease positive; blackens triple sugar iron agar Proteus commonly causes urinary tract infections. Liberation of ammonia by urease increases urine pH, which increases the potential for struvite stone development.Colorless colonies on MacConkey agar; oxidase negative; no gas on triple sugar iron agar Shigella is characterized by its virulence—only 100 bacteria must be ingested to develop shigellosis. Person-to-person acquisition is common, via fingers, flies, food, and feces. Symptoms begin as fever and abdominal pain, progressing to watery diarrhea, which later consists of blood and mucus. No rash is associated with shigellosis. Lactose is not fermented, as evidenced by colorless colonies on MacConkey agar.Colored (pink) colonies on MacConkey agar; urease positive Klebsiella is found in the large intestine, soil sources, and water sources. The thick capsule is characteristic of this bacterium. Klebsiella causes pneumonia in the elderly, diabetic patients, patients with chronic obstructive pulmonary disease, and alcoholics. Pink coloration on MacConkey plates indicates lactose fermentation. Current jelly sputum, necrosis, and abscess formation are commonly associated with pneumonia caused by Klebsiella.Colored (pink) colonies on MacConkey agar; metallic green sheen on EMB agar Escherichia coli causes diarrhea, urinary tract infections, hemolytic–uremic syndrome, and meningitis. Pink
  10. 10. coloration on MacConkey plates indicates lactose fermentation.A great increase cardiac output and GFR Prazosin does not greatly affect cardiac output, renal perfusion. or GFR; rather, its action is to decrease arterial and venous resistance. There is some effect but it is not a dramatic oneA high risk for syncope Syncope often is a side effect of alpha inhibitors. It is often associated with the first dose, but prazosin is usually given at night to prevent this side effect.Increased tone in the smooth muscle of the bladder and prostate, leading to decreased urinary retention The tone in the prostate gland is decreased, which leads to the decrease in urinary retention.An association with bradycardia Alpha blockers are associated with tachycardia. Beta blockers decrease the sympathetic tone on the heart, thereby reducing chrontopic stimulation to the heart. The alpha blockers affect only the resistance of the blood circuit, so in response to a relatively low blood pressure the sympathetic nervous system stimulates the heart to beat faster and harder.Chagas disease This disease is caused by infection with Trypanosoma cruzi. It is spread by reduviid insects, typically in South America. A nodule, or chagoma, forms at the site of the insect bite. Later complications include megacolon, megaesophagus, and cardiac abnormalities (conduction block).Gonorrhea While disseminated gonorrhea can cause joint pains, infection with the responsible organism is better known for its monoarticular manifestations. In addition, it is not associated with cranial nerve palsies.
  11. 11. Lyme disease Borrelia burgdorferi is a tick-borne spirochete that is classically associated with erythema chronicum migrans, often missed by patients. This patient manifested other signs, such as her malaise and arthralgias. Her facial droop is also a classic finding for Lyme disease. A tetracycline will be helpful in eradicating the disease.Rocky Mountain spotted fever This disease is caused by infection with a tick- borne rickettsia (R. rickettsii). It presents with headache, fever, and a generalized skin rash (palms and soles first).Sleeping sickness Also known as African trypanosomiasis, sleeping sickness is not found on the Eastern Seaboard of the United States. Fever, lymphadenopathy, joint pains, and CNS changes are characteristic.HIV This patient is presenting with Pneumocystis carinii pneumonia, which is very often the way HIV is diagnosed. Unfortunately, this patient likely has a CD4 count less than 200, which means that his infection is quite advanced. First-line treatment is to get an ABG and, if the PO2 is less than 70, start steroids, along with high-dose IV trimethoprim- sulfamethoxazole.Pasturella multocida This infection is often associated with pain and limited motion to an extremity, which can lead to osteomyelitis.Hypertensive emergency This condition is typically seen in patients who have end-organ damage, such as retinal changes, mental status changes, or renal dysfunction. It does not specifically present with a picture typical for pneumonia.Plague The plague (Yersinia pestis infection) typically presents with tachycardia, tender lymph nodes (particularly inguinal),
  12. 12. high fever, malaise, and myalgia. It can also be associated with a lobar process on CXR.Pulmonary tuberculosis While the malnourishment fits this diagnosis, the severe hypoxia is more indicative of PCP.Chloroquine One would not use chloroquine against chloroquine-resistant species of Plasmodia.Iodoquinol This luminal amebicide may be used against Entameba histolytica, but not against any species of Plasmodia.Mefloquine Mefloquine is used for prophylaxis in cases where a patient is predicted to be exposed to chloroquine-resistant P. falcipartum, as in this case. A blood schizonticide, it has no effect on extraerythrocytic stages of the malarial parasite. Therefore, mefloquine does not act against P. ovale or P. vivax, which left this patient vulnerable to malaria caused by infection with one of these species.Pentamidine This drug is used for trypanosomiasis and in Pneumocystis carinii pneumonia, but not against malaria.Primaquine Primaquine is used for prophylaxis in cases where a patient is predicted to be exposed to P. ovale or P. vivax. This patient was treated with a drug that would decrease her chances of getting malaria via P. falcipartum. Primaquine is a tissue schizonticide that works by forming cellular oxidants.Pyrimethamine This antifolate drug blocks folic acid synthesis in susceptible protozoa. A blood scizonticide, it acts primarily
  13. 13. against P. falcipartum. This drug is not used for prophylactic purposes.Eating undercooked beef is usually how the infection occurs. Taenia saginata (beef tapeworm) is the cause of infection when undercooked beef is ingested.In addition to residing in the colon, the infectious agent can migrate to the lung. Filariaris, Pargonimiasis, and Echinoccus are helminths that have been known to migrate to the lung. Enterobius resides only in the colon.It is diagnosed by looking for proglottids in the stool. Proglottids can be found in the stool of persons infected with Taenia saginata and Taenia solium (pork tapeworm)It is diagnosed with the ‘Scotch-tape test.’ With Enterobius vermicularis, female worms leave the anus at night, lay eggs, and die. This causes severe anal itching. Placing Scotch tape over the area at night will pick up the eggs, which can then be examined under a microscope to confirm the diagnosis.Enterobius is transmitted via the fecal-oral routeContinue frequent breast feeding and take an antibiotic. Frequent breast feeding has been shown to shorten the clinical course of mastitis along with antibiotic treatment. The organisms will be killed in the infants stomach, and the antibiotic must be safe for infants.Stop nursing and let the infection heal. This will likely lengthen the clinical course and possibly cause abscess
  14. 14. We will set you up for a mammogram today. There is no current indication for mammogram. Also, due to the density of the breast tissue, the study would not find many small cancers if they existed.Amyotrophic lateral sclerosis ALS is characterized by both upper and lower motor neuron loss in the spinal cord, brainstem, and motor cortex. It is a chronic, progressive, degenerative disease.Conversion disorder Conversion disorder is a psychiatric diagnosis for people with multiple symptoms that cannot be explained by a medical cause. There must be psychological issues related to the onset, although the patient is not conscious that these reasons are why the symptoms have occurred.Multiple sclerosis MS is a demyelinating disease characterized by multiple neurologic complaints that are set apart by time and space, and that cannot be explained by a single lesion. It is typically relapsing-remitting, with symptoms that abate for a period of months to years before other symptoms appear. It typically is worsened by heat.Myasthenia gravis MG is an autoimmune disease characterized by antibodies that bind to post-synaptic acetylcholine receptors. It commonly affects eyesight and causes fluctuating fatigable ptosis or double vision. Symptoms typically worsen during the day.Parkinsons disease Parkinsons disease usually occurs in people older than 50 years. It is caused by dopamine depletion in the substantia nigra. Typical symptoms include bradykinesia, resting tremor, shuffling gait, stiffness, and fatigue.Adenosine phosphoribosyl transferase Adenosine phosphoribosyl transferase is an enzyme used in the salvage pathway of purines. It is involved in the final step of the pathway, the conversion of adenine to AMP.
  15. 15. Hypoxanthine-guanine phosphoribosyl transferase Hypoxanthine-guanine phosphoribosyl transferase (part of the salvage pathway for purines) deficiency leads to Lesch–Nyhan syndrome, which is the clinical picture presented in this case. This is an X-linked metabolic disease. These patients will have hyperuricemia and should be treated with allopurinol. These patients are also mentally retarded.Nucleoside diphosphate kinase Nucleoside diphosphate kinase is involved in nucleotide synthesis—specifically, the conversion of nucleoside diphosphates to nucleoside triphosphates, and vice versa.Purine nucleoside phosphorylase Purine nucleoside phosphorylase converts guanosine to guanine and inosine to hypoxanthine in the formation of uric acid.Xanthine oxidase Xanthine oxidase is used in the formation of uric acid. It oxidizes hypoxanthine to xanthine and xanthine to uric acid.Asbestos exposure This condition is typically found in shipyard workers from years ago. The disease process is not normally acute and leads to the classic cancer mesothelioma.Asthma exacerbation You would expect to see a lower oxygen saturation level, along with wheezing or decreased air movement on exam.Carbon monoxide poisoning Anyone who comes in with a 100% oxygen saturation and in severe respiratory distress with a normal exam should be considered for CO poisoning. This
  16. 16. condition can result from inhalation of car exhaust or an old gas heater that has just been started up on a cold night. The diagnostic test is the ABG, which reveals carboxyhemoglobin. The treatment is oxygen, hyperbaric if available. Carbon monoxide has a very high affinity for hemoglobin; once it binds, it causes the other three sites in the hemoglobin to be less likely to bind oxygen.Pneumonia This diagnosis is a possibility but is less likely if the patient is in this much distress and has a 100% oxygen saturation.Pulmonary embolism The oxygen saturation is too high, although the acute onset of the illness is in line with this diagnosis. A blood gas would be useful in this setting, where you would expect a low PaO2.The G2 phase involves checking DNA for errors. This phase follows immediately the S phase, in which DNA is made. This phase is involved in checking DNA for errors.In the cell cycle, most cells spend the majority of time in mitosis. Cells typically spend the majority of time in interphase.Mitosis involves semiconservative replication, and DNA is typically circular. Mitosis does involve semiconservative replication, in which daughter DNA is partnered with parental DNA. DNA is typically not circular.Most epithelial cells remain in the G0 phase. G0 is a phase that indicates a cell is no longer actively dividing. Epithelial cells are actively dividing and are not in the G0 phase.Reverse transcription plays a significant role in DNA replication. Reverse transcription plays a limited role in cell replication. It is
  17. 17. involved in replication of highly repetitive sequences of DNA.Antisocial personality disorder Patients with antisocial personality disorder avoid conforming to societal norms and are not concerned with the welfare of other people, animals, and objects.Avoidant personality disorder Avoidant personality disorder is a cluster C personality disorder. Patients with avoidant personality disorder feel inferior to others, avoid interacting with others, and are sensitive to rejection.Histrionic personality disorder Histrionic personality disorder is a cluster B personality disorder. Patients with this personality disorder are theatrical and extroverted. They will often try to sexually seduce others, but they avoid intimate relationships.Narcissistic personality disorder Narcissistic personality disorder is a cluster B personality disorder. Patients with narcissistic personality disorder believe that they are more important than others and are insensitive to the needs of others.Paranoid personality disorder Patients with paranoid personality disorder (a cluster A personality disorder) are distrustful of other people and do not take responsibility for their own problems.17 and older A person has a good chance of attaining stage IV ethics by age 17 or older, at which point right behavior is viewed as lawful behavior. Life is seen as sacred in terms of its place in a categorical moral or religious order.
  18. 18. Change the antibiotic because it is unlikely to cover Streptococcus bovis Vancomycin and gentamicin provide broad empiric coverage of all the likely organisms of infective endocarditis: Streptococcus viridans and bovis, and Staphylococcus aureus and epidermitis.Consult GI to initiate a GI workup Streptococcus bovis is associated with a 50% risk of colonic malignancy, making a GI workup mandatory.Consult Infectious Disease for the unusual nature of the organism Streptococcus bovis is one of the normal organisms for infective endocarditis. Blood cultures are positive in approximately 90% of patients. Those for whom it is not positive often have an unusual organism.Consult Social Service because the patient is a likely drug abuser Right-sided endocarditis is usually associated with IV drug use. Tricuspid, rather than mitral, regurgitation would be expected.No change is management is necessary at this time With such a strong association of S. bovis with colonic malignancy, one would be remiss in not investigating it.Anomalous insertion of odd-chain fatty acids into membrane lipids The patient is pale, which might suggest anemia. The most consistent sign of B12 deficiency is loss of vibration sense in the legs, which can extent to the trunk. Changes in mental status are frequently observed and include irritability, confusion, suspiciousness, and emotional instability. Lack of cobalamin leads to accumulation of methylmalonyl CoA and propionyl CoA. Excess propionyl CoA leads to displacement of succinyl CoA, which results in formation of anamolous odd-chain fatty acids in membrane lipids.
  19. 19. Prescribe a trial of ativan Night terrors are nightmares that are not recalled.Prescribe a trial of imiprimine Imiprimine is used for bedwetting.Prescribe a trial of phenobarbital Phenobarbital lessens REM sleep.Psychiatric referral for forgotten trauma Forgotten trauma does not usually present with isolated nightmares that are never remembered upon waking and that usually occur during the first half of the night. They can be familial. Ativan is a benzodiazepine that lessens stage IV sleep. Night terrors occur during stage IV sleep, so benzodiazepines are often helpful for night terrors.Which hormone is responsible for insulin resistance in gestational diabetes mellitus?hPL Human placental lactogen is believed to be the main culprit in the development of GDM in pregnant women. This hormone, which is produced in the placenta, is important for ensuring a constant nutrient supply to the fetus. It causes lipolysis and hence increases free fatty acids. It also has diabetogenic effects on the mother and leads to increased levels of insulin and development of diabetes.hCG is not believed to play a role in the development of GDM.Estrogen Estrogen is not believed to play a role in the development of GDM.LH Luteinizing hormone is not believed to play a role in the development of GDM.Progesterone Progesterone is not believed to play a role in the development of GDM.He complains of a circular, red, itchy patch of skin on his right forearm.
  20. 20. This is a dermatophyte infection of a microsporum species. Certain microsporum species, when hairs are involved, will fluoresce under a Woods lamp. Microsporum species infect only hair and skin.This is a dermatophyte infection of the epidermophyton species. Epidermophyton species do not fluoresce under a Woods lamp. E. floccosum infects skin and nails, but not hair.Further examination of this area is warranted to narrow down the fungal species infecting the individual. Of the species that cause dermatophyte infections, only microsporum will fluoresce under a Woods lamp.This is a dermatophyte infection of a trichophyton species. Lyme disease is caused by Borrelia bergdorferi, which is transmitted by a tick bite.This is an erythema migrans rash of Lyme disease. The erythema migrans rash, which is usually described as a ‘bull’s-eye rash, does not fluoresce under a Woods lamp. It is the hallmark rash of Lyme disease. Lyme disease is caused by infection with Borrelia bergdorferi, which is transmitted by a tick bite.Epidural hemorrhage An epidural hemorrhage may follow a blow to the head. It usually presents with a brief loss of consciousness, followed by a lucid interval that may last several hours, followed by drowsiness and coma. Bleeding is usually from a torn artery, most commonly the middle meningeal artery.Intracerebral hemorrhage Intracerebral hemorrhages are most commonly seen in patients with hypertension. They may produce a paralytic stroke.
  21. 21. Subhyaloid hemorrhage A subhyaloid hemorrhage is a hemorrhage in the eye between the retina and vitreous body. It may be seen in conjunction with a subarachnoid hemorrhage.Subarachnoid hemorrhage A subarachnoid hemorrhage most commonly occurs as the result of an aneurysm of an intracranial artery. It results in signs of meningeal irritation, such as severe headache, stiff neck, and loss of consciousness. There is no lucid interval.Subdural hemorrhage This injury typically follows a blow to the head that forcefully moves the brain inside the skull. It is seen most commonly in the elderly population secondary to shrinkage of the brain. There is no lucid interval.Common hepatic artery The common hepatic artery runs along the upper edge of the pancreas before dividing into the proper hepatic artery and gastroduodenal artery. It is not found near the cystohepatic triangle.Cystic artery The cystic artery travels through the cystohepatic triangle and is the most likely artery to be injured during a cholecystectomy.Left hepatic artery The left hepatic artery supplies the left portion of the liver. It is not located near the cystohepatic triangleRight gastric artery The right gastric artery supplies the stomach and is not likely to be injured during a cholecystectomy.Right hepatic artery The right hepatic artery supplies the right side of the liver and gives rise to the cystic artery, which lies in the cystohepatic triangle. While it may be injured during a
  22. 22. gallbladder surgery, it is not the most common artery damaged during dissection of that area.P. falciparum The most feared form, it causes malignant malaria, which can manifest as cerebral malaria. Cerebral malaria can lead to coma and is associated with a mortality rate in excess of 20%.P. malariae This organism causes benign quartan malaria. When chronic, P. malariae infection is also associated with nephrotic syndrome due to glomerulonephritis.P. ovale This organism causes benign tertian malaria. One important consideration with this parasite is that hypnozoite forms can be present in the liver, causing relapse. For this reason, primaquine must be added to the therapy.P. simiovale This strain infects simian species. The four human malarial species are P. falciparum, P. ovale, P. vivax, and P. malariae.P. vivax This organism causes benign tertian malaria. One important consideration with this parasite is that hypnozoite forms can be present in the liver, causing relapse. For this reason, primaquine must be added to the therapy. In addition, P. vivax can be associated with delayed splenic rupture.Routine lab work shows an elevated bilirubin level of 2.3 mg/dL (normal = 0.2– 1.0 mg/dL).Gilberts syndrome Gilberts syndrome is often found by the presence of an elevated bilirubin level on routine lab work in an otherwise asymptomatic individual. The bilirubin level fluctuates, and may be elevated by stress, exercise, infection, or fasting. Patients may notice scleral icterus or mild
  23. 23. jaundice of the skin during these periods. Gilberts syndrome affects 3% to 7% of the population and is more common in males than in females. The hyperbilirubinemia is caused by reduced hepatic glucuronyl transferase activity.Cirrhosis This patient has no risk factors for cirrhosis, including no reports of excessive alcohol use, no hepatosplenomegaly, and normal liver function tests.Crigler–Najjar syndrome type I In Crigler–Najjar Syndrome type I, the patient has no glucuronyl transferase, kernicterus, and early death.Crigler–Najjar syndrome type II In Crigler–Najjar syndrome type II, the patient has low levels of glucoronyl transferase. Patients are usually diagnosed early in life, with severe jaundice and a bilirubin level of 9–17 mg/dL.Hemolytic anemia Hemolytic anemia is characterized by an elevated bilirubin level; however, the complete blood count would reveal decreased hemoglobin and hematocrit levels. The patient would also have an elevated reticulocyte count.Decreased calcium, increased phosphate, normal alkaline phosphatase A patient with decreased calcium, increased phosphate, and normal alkaline phosphatase would most likely present with renal insufficiency.Normal calcium, normal phosphate, increased alkaline phosphatase A patient with normal calcium, normal phosphate, and increased alkaline phosphatase would not suggest osteoporosis.
  24. 24. Increased calcium, decreased phosphate, increased alkaline phosphatase A patient with increased calcium, decreased phosphate, and increased alkaline phosphatase would not have osteoporosis but could be a candidate for hyperparathyroidism.Increased calcium, increased phosphate, normal alkaline phosphatase These lab results would not suggest osteoporosis but could suggest vitamin D intoxication.Normal calcium, normal phosphate, normal alkaline phosphatase This patient most likely has osteoporosis; therefore, her calcium, phosphate, and alkaline phosphatase would most likely be normal.For which of the following cases is confidentiality allowed to be broken?A patient is confides in you her plan for killing another person A person with a plan to harm another person needs to be taken seriously. If there is no other way to warn the person at risk, it is the obligation of anyone who knows of this plan to break confidentiality.A husband calls your office for his wifes test results without having her explicit permission to give out any information This scenario does not meet the requirements for breach of confidentiality.A parent asks you whether her teenage daughter has been taking birth control pills In most states, teenagers are granted confidentiality from their parents regarding sexual matters.The local TV station contacts the emergency room to verify whether a celebrity has been recently treated All patients, including celebrities, have the right to privacy and not to have their presence confirmed or denied unless they authorize it.
  25. 25. Lysosomal storage Diseases such as Gaucher disease do not give the clinical findings described here.An alpha-1,6-glucosidase deficiency In Coris disease, patients lack a debranching enzyme.A glucose-6-phosphatase deficiency In Von Gierkes disease, patients exhibit severe fasting hypoglycemia and have increased amounts of liver glycogen.A glycogen phosphorylase enzyme deficiency In McArdles disease, patients exhibit cramps and weakness after minimal exertion.A lysosomal glucosidase deficiency In Pompes disease, patients often die within the first year because of a defective ‘pump.’Which of the following hormones is responsible for stimulating pancreatic enzyme secretion, stimulating gallbladder contraction, and inhibiting gastric acid secretion?Cholecystokinin Cholecystokinin is responsible for these activities. It is stimulated by amino acids and fatty acids.Gastrin Gastrin stimulates gastric motility and the secretion of pepsinogen, hydrochloric acid, and intrinsic factor.Pepsin Pepsin is stimulated by acid and begins the process of protein digestion.Secretin Secretin inhibits gastric acid secretion and stimulates bicarbonate secretion by the pancreas.
  26. 26. Somatostatin Somatostatin inhibits gallbladder contraction, pancreatic fluid secretion, small-bowel fluid secretion, gastric acid secretion, and pepsinogen secretion. It is responsible for the release of glucagons and insulin.Antisocial personality disorder Antisocial personality disorder is a cluster A personality disorder. Patients with conduct disorder in childhood have an increased risk of developing antisocial personality disorder. Patients with antisocial personality disorder will avoid conforming to societal norms and are not concerned with the welfare of other people, animals, and objects.Avoidant personality disorder Avoidant personality disorder is a cluster C personality disorder. Patients with avoidant personality disorder feel inferior to others, avoid interacting with others, and are sensitive to rejection.Histrionic personality disorder Histrionic personality disorder is a cluster B personality disorder. Patients with this personality disorder are theatrical and extroverted. They will often try to sexually seduce others, but they avoid intimate relationships.Narcissistic personality disorder Narcissistic personality disorder is a cluster B personality disorder. Patients with narcissistic personality disorder believe that they are more important than others and are insensitive to the needs of others.Paranoid personality disorder Patients with paranoid personality disorder (a cluster A personality disorder) are distrustful of other people and do not take responsibility for their own problems.Group B streptococci, E. coli, and Listeria Group B streptococci, E. coli, and Listeria are the common causes of meningitis in newborns.
  27. 27. Listeria and E. coli While Listeria and E. coli are common causes of meningitis in the newborn, answer A is correct because it includes Group B streptococci, a common cause of meningitis in newborns.N. meningitidis and H. influenzae B N. meningitidis and H. influenzae B are common causes of meningitis in children, but not newborns. The incidence of infection with H. influenzae B is decreasing due to the widespread use of the prevnar vaccine against this pathogen.S. pneumoniae and gram-negative rods S. pneumoniae is an uncommon cause of meningitis in newborns, but it is a common cause of meningitis in children and adults. Gram-negative rods are a common cause of meningitis in the elderly.Staphylococcus aureus and Klebsiella pneumoniae Staphylococcus aureus and Klebsiella pneumoniae are rare causes of meningitis.Decreased number of CD4 count and increased p24 antigen One month after infection with HIV, patients will have decreased levels of CD4 lymphocytes; this level eventually increases two to three months after infection. One month after infection, p24 antigen levels peak and then decrease by two months post-infection.Increased anti-gp120 antigen Anti-gp120 antigen does not appear until 6 weeks after infection and peaks around 8–12 weeks post-infection.Increased anti-p24 antigen Anti-p24 antigen does not appear until 6 weeks after infection and peaks Normal CD4 count and increased p24 antigen One month after infection with HIV, patients will have decreased levels of CD4 lymphocytes; this level
  28. 28. eventually increases two to three months after infection. around 8–12 weeks post-infectionNormal CD4 count and increased p24 antigen One month after infection with HIV, patients will have decreased levels of CD4 lymphocytes; this level eventually increases two to three months after infection. One month after infection, p24 antigen levels peak and then decrease by two months post-infection.Normal CD4 count and undetectable p24 antigen One month after infection with HIV, patients will have decreased levels of CD4 lymphocytes; this level eventually increases two to three months after infection. One month after infection, p24 antigen levels peak and then decrease by two months post-infection.The husband suffers from a kinesin deficiency The deficiency is in the dynein proteinThe patient suffers from Kartageners syndrome The constellation of infertility, bronchiectasis/sinusitis, and situs inversus should make you think of Kartageners syndrome. These patients suffer from a deficiency of the dynein protein found in cilia that is responsible for ciliary motion. In the absence of this critical protein, males are infertile secondary to sperm immobility. The lack of proper ciliary motility also means decreased bacterial clearance from the lungs and sinuses, resulting in bronchiectasis and chronic sinusitis. The situs inversus is secondary to improper cell mobility during embryogenesis.Flutamide The patient has metastatic carcinoma of the prostrate. He has a history of BPH, which is common in men older than 50 years of age. Superimposed on the BPH the patient has developed prostate cancer that has now metastasized to his spine—not an uncommon mode of presentation for prostate cancer. Flutamide is an oral anti-androgen at the level of the prostate gland and prostate cancer cells. It
  29. 29. blocks the stimulation signal for proliferation in these cells and controls the rate of cell replication.Actinomycin D This drug binds to double-stranded DNA and inhibits DNA- directed RNA synthesis. It is not indicated for prostate cancer.Carboplatin This drug binds to DNA and creates interstrand cross links. It is not indicated for prostate cancer.Interferon-alpha, -beta, or -gamma Interferons are not indicated for prostate cancer.Mitomysin C This alkylating drug is not indicated for prostate cancer.A 24-year-old male is thrown from a car that he drove into a tree. He suffers from a T6 spinal crush injury. After he recovers from his acute injury, what is the most appropriate course of action regarding his bladder?The bladder should remain catherized until the patients micturation reflexes return. The patient can then be taught to cutaneously stimulate the genital area to stimulate a micturation reflex. In this case, spinal shock causes complete suppression of the micturation reflex for the first few days.The patient will have frequent bladder reflux with resulting bladder infections. Bladder dyssynergia can be caused by upper spinal cord lesions, which causes ureteral reflux.The bladder is paralyzed, and the patient will have to use abdominal compression and straining to void. Bladder paralysis will be caused by
  30. 30. lesions below T12. Abdominal straining and compression, called Credes maneuver, will often allow voiding.The patient will have a bladder that fills and dribbles urine continually. Lesions that affect the sensory nerves prevent normal micturation reflex. The bladder will fill to capacity and overflow a little at a time.The patient should be taught how to self-catherize, because he will never be able to control his bladder. Self-catherization is appropriate if the patient can never control his bladder. This permanent condition can be caused by loss of sensory nerves.Codeine This drug is a narcotic. Narcotics have an addictive potential.Heroin This drug is a narcotic. Narcotics have an addictive potential.Hydrocodone This drug is a narcotic. Narcotics have an addictive potential.Morphine This drug is a narcotic. Narcotics have an addictive potential.Tramadol This agent is the only non-narcotic drug on the list. A patient with a history of substance abuse (no matter what the substance of abuse was) must not be given medications that have the potential to be addicting and abused. The diagnosis of substance abuse is a lifetime diagnosis. Patients so diagnosed, even if their addiction resolves, continue to maintain that diagnosis for life.A 25-year-old female has recently had her first psychotic break. After many months of therapy, she has been diagnosed with paranoid schizophrenia. She has been responding well to her inpatient olanzapine regimen, and you would like to continue this medication with her while following her in the outpatient setting. Which of the following features of her family history would be of the greatest concern to you?Three first-degree relatives with type II diabetes mellitus There is an established genetic component to type II diabetes mellitus. Olanzapine has been shown to cause significant increases in weight, which in turn promotes a state of hyperinsulinemia and insulin resistance. It would be worrisome to start a patient
  31. 31. with a significant family history of diabetes mellitus on a medication that would further increase her risk of developing this disease via weight gain and insulin resistance.A 65-year-old woman comes into your office complaining of a left-sided headache, jaw pain, and stiff, achy shoulders for about one week. She has no other medical problems and has never had a headache before this presentation. On examination, she has a prominent, pulsating left temporal artery that is very tender to palpation. You suspect temporal arteritis (giant-cell arteritis) and decide to do a biopsy to confirm the diagnosis. What is the best course of action in the meantime, while waiting for the results?High-dose prednisone A serious consequence of untreated temporal arteritis is blindness due to inflammation extending to the optic nerve. If your clinical suspicion is high, it is best to start steroids immediately. If the biopsy is negative for temporal arteritis, the short course of steroids is unlikely to have any adverse effects.Tylenol for headache relief Although Tylenol can help relieve pain symptoms and could be given as an adjuvant to treatment, it is also important to start the patient on steroids.Nothing; wait for results before giving any treatment Any delay in treatment while waiting for the results increases the patients risk of blindness.Antibiotics Temporal arteritis is not an infectious process, but rather is caused by chronic inflammation of large blood vessels. Antibiotics would not help reduce the inflammation.Have other family members come in for evaluation Temporal arteritis is not a hereditary process. However, its incidence increases with advancing age. If family members present with similar complaints, it is best to have them evaluated.
  32. 32. During a busy day in the emergency room, a 37-year-old male presents complaining of acute epigastric abdominal pain, describing it as ‘shooting straight through to my back.’ He also states that he has not been able to eat because of nausea and vomiting. On examination, the patient is afebrile and uncomfortable, and he requests medication for his pain. He appears intoxicated. The abdominal exam reveals mild distention, absent bowel sounds, and extreme pain on palpation, but no rebound tenderness. Initial lab results show elevated amylase and lipase levels. A KUB shows multiple calcifications in the abdomen. Which diagnosis best explains these results?Pancreatitis In the setting of alcohol use, this patients presentation is convincing for acute pancreatitis in the context of chronic pancreatitis. Alcohol use and gallstones are the main causes of acute pancreatitis in the United States; the presence of pancreatic calcifications suggests that the patient has experienced previous episodes. A follow-up CT scan or ultrasound may reveal pancreatic fluid collections, indicating the development of a pseudocyst.Aortic dissection Patients with aortic dissection classically complain of intense epigastric pain that radiates to the back, but do not have elevated lipase and amylase levels.Appendicitis This patient presents with acute, fixed, and intense epigastric pain. Appendicitis typically begins as colicky central abdominal pain that worsens as it localizes to the right- lower quadrant. It is not generally associated with elevated lipase levels.Esophagitis Erosive conditions of the esophagus are not associated with elevated amylase and lipase levels.
  33. 33. Gastritis Although patients with gastritis often present with epigastric pain and nausea, serum amylase and lipase levels are not typically elevated. In addition, abdominal calcifications in this setting are strongly suggestive of pancreatic calcifications, indicating that the patient likely has a chronic condition.As an intern in the ER, you evaluate a 55-year-old patient with a history of a duodenal ulcer who complains of severe, nonremitting, mid- epigastric pain and vomiting of bright red blood. An upright X ray reveals free air under the diaphragm, and you suspect a perforated ulcer. Endoscopy confirms your suspicion and reveals a perforated ulcer in the posterior portion of the first part of the duodenum. Perforation into which artery best explains this patients symptoms?Gastroduodenal artery This artery descends immediately behind the first part of the duodenum; ulcers commonly penetrate into this vessel. It arises from the common hepatic artery and gives off the right gastroepiploic and superior pancreaticoduodenal arteries.Cystic artery This artery does not run near the first portion of the duodenum.Hepatic artery The right and left hepatic arteries are branches of the proper hepatic artery, which is itself a branch of the common hepatic artery. These arteries are closer to the liver and the second portion of the duodenum.Right gastric artery This artery runs along the lesser curvature of the stomach away from the duodenum.Right gastroepiploic artery This artery runs along the greater curvature of the stomach.
  34. 34. According to current thinking, which of the following is the first-line treatment for congestive heart failure?ACE inhibitors ACE inhibitors decrease vascular resistance, decrease blood pressure, and increase cardiac output. They also blunt the release of aldosterone and epinephrine caused by angiotensin II. Studies have shown that ACE inhibitors reduce the chances of arrhythmic death, MI, and stroke. Interestingly, studies scheduled to be published in the near future may make new statements about ACE inhibitors and beta blockers, so this answer may change in the future. Currently, however, ACE inhibition is the correct answer for this question.Beta blockers Once thought to be contraindicated in CHF, these medicines are now finding a place in the treatment of CHF and the prevention of further disease and complication. They are not the first-line option, however.Digitalis Widely used in heart failure, digitalis has no effect on mortality and is not used as a first-line therapy. Its utility actually derives from its ability to decrease the number of hospitalizations of patients with CHF.Diuretics While useful in heart failure because of its ability to reduce the effects of volume overload and decrease the symptoms of paroxysmal nocturnal dyspnea and orthopnea, diuretics are is not the first-line option for CHF.Macrolides This class of drugs, and all classes of antibiotics, have not been shown to offer any benefits in the treatment of CHF.A 25-year-old woman with regular menses is given an estrogen challenge. The challenge consists of exogenous estrogen supplementation to see if her LH level will increase. Which of the following regimens would be most effective?Estrogen 10 days after menses High levels of estrogen are needed to stimulate adequate LH production.
  35. 35. Estradiol 20 days after menses If estradiol was given 20 days after menses, then the cycle would already be in the luteal phase. Once in the luteal phase, the LH level will not rise until the next cycle.Progesterone 10 days after onset of menses Progesterone level is typically very low during the follicular phase. This hormone does not stimulate LH production.Progesterone 20 days after onset of menses Progesterone does not stimulate LH production.Synthetic FSH 15 days after onset of menses FSH is the not the principal stimulator of LH production.A 47-year-old African American male presents for follow-up for depression. He denies improvement after eight weeks of sertraline with good compliance. His smoking has increased to three packs per day, up from two packs per day for 30 years. He admits to intermittent back pain, incapacitating pruritus, and a 30-pound weight loss. Umbilical tenderness and a distended gallbladder are noted on physical examination. Which of the following is the most likely to be true in this case?The pancreatic head is the origination site of the patients pancreatic carcinoma. Pancreatic carcinoma most often occurs in the pancreatic head. This location allows earlier identification as compared to the tail of the pancreas. However, surgical procedures require removal of the pancreatic head, gallbladder, and a portion of the duodenum (Whipple procedure). Migrating thrombophlebitis is often observed with pancreatic carcinoma.No association has been made between cigarette smoking and pancreatic carcinoma. Smoking increases the risk of pancreatic carcinoma.
  36. 36. The patients tumor represents the malignant transformation of exocrine cells. Duct cells represent 4% of the healthy pancreas, but 99% of primary pancreatic malignancies originate from duct cell neoplasia.The patients gallbladder distention is due to choledocholelithiasis from elevated cholesterol nucleation. Courvoisiers sign notes the tendency of biliary-tract–related malignancies to lead to gallbladder distention, but cholelithiasis-related disease results in a normal- or reduced-size gallbladder.Lifespan has been improved to greater than 10 years with current chemotherapy regimens. The prognosis for pancreatic carcinoma remains poor, with death typically occurring within one year of diagnosis.A four-year-old white female presents to the pediatric clinic for follow-up due to developmental delay. Her medical history reports frequent episodes of otitis media, bronchitis, and pneumonia. Physical examination reveals coarse facial features, gingival hypertrophy, joint stiffness, claw hand deformity, and generalized hypotonia. Significant motor delay is appreciated. Electron microscopy of muscle biopsy demonstrates numerous intracytoplasmic inclusions, which are membrane-bound vacuoles filled with fibrillogranular material. I-cell disease is suspected. What is the function of the deficient enzyme?Phosphorylation of mannose residues Failure to phosphorylate mannose residues targets intracellular enzymes to extracellular sites. Lysosomal enzymes cannot be routed appropriately, and enzymes accumulate in the plasma. Lysosomal substrates accumulate, as the lytic enzymes are not present intracellularly. Key findings are gingival hypertrophy and hypotonia. Death is common before the patient reaches age eight years.Breakdown of dermatan sulfate and heparan sulfate Mucopolysaccharidoses and another class of lysosomal disorders, Hurlers syndrome, Hunters syndrome, Scheies syndrome, and
  37. 37. Sanfilippos syndrome are all disorders due to faulty metabolism of dermatan sulfate and heparan sulfate. Hurlers syndrome and Scheies syndrome are notable for corneal clouding. Scheies syndrome is the only listed disorder with normal intellect and life expectancy. Hunters syndrome is X-linked, where the remaining disorders are autosomal recessive.Cleavage of disaccharides Brush border enzymes include lactase and isomaltase sucrase. These disorders cause flatulence due to bacterial digestion of disaccharides and osmotic diarrhea.Cleavage of fructose Fructose intolerance is caused by lack of aldolase B. Phosphorylated fructose accumulates within the cell due to insufficient metabolism. Possible sequelae include hypoglycemia, hemorrhage, and liver failure. Avoidance of fructose and sucrose is curative.Degradation of sphingolipids Lysosomal hydrolytic enzymes are missing in this class of enzyme deficiencies. Sphingolipidoses include Tay-Sachs disease, Meimann-Pick disease, and Fabrys disease. Lysosomal accumulation of sphingolipids often leads to mental retardation and shortened life expectancy.Metabolism of galactose Galactosemia, as caused by uridyltransferase or galactokinase deficiency, may lead to adverse effects that include cataract formation and mental retardation. Accumulation of galactitol damages nerve tissue, liver, kidney, and the lens of the eye. Strict avoidance of galactose and lactose is required.Which of the following antibiotics works by blocking cell-wall synthesis through the inhibition of peptidoglycan cross-linking?Penicillin Along with the cephalosporins, imipenem and actreonam, penicillin inhibits peptidoglycan cross-linking.
  38. 38. Aminoglycosides Block protein synthesis at the 30S ribosomal subunit, as do the tetracyclines.Chloramphenicol Blocks protein synthesis at the 50S ribosomal subunit.Clindamycin Blocks protein synthesis at the 50S ribosomal subunit.Macrolides Block protein synthesis at the 50S ribosomal subunit.Quinolones Block DNA topoisomerases.Rifampin Blocks mRNA synthesis.Sulfonamides Block nucleotide synthesis.Vancomycin Blocks peptidoglycan synthesis.

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