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27 Cards in this Set
- Front
- Back
Acyclovir
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Anti-viral against herpes viruses
-acyclovir can cause crystalline nephropathy if adequate hydration is not also provided. -when acyclovir concentration in collecting duct exceeds solubility, crystallization, crstalluria, and renal tubular damage may result -in most cases, this toxic complication is transient and can be prevented/treated with adequate hydration and dosage adjustment (slowing rate of IV infusion) |
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Atherosclerotic plaques and acute coronary syndrome (MI)
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-plaque rupture can produce an acute coronary syndrome via superimposed thrombosis and/or thromboembolism
-likelihood of plaque rupture (or other change) has more to do with plaque stability the plaque size. -plaque stability depends on mechanical strength of overlying fibrous cap – weak fibrous cap increases probability of plaque rupture |
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-Chronic inflammatory progression of an atheroma
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-during chronic inflammatory progression of an atheroma, the fibrous cap is continually being remodeled
-balance of collagen synthesis and degradation determines mechanical strength of cap. -activated macrophages in the atheroma contribute to collagen degradation by secreting METALLOPROTEINASES -high intraplaque activity of metalloproteinases predisposes plaque to rupture --> acute coronary syndrome, including myocardial infarction |
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Mucormycosis
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-Mucormycosis strongly associated with DIABETIC KETOACIDOSIS
-Mucor, Absidia, and Rhizopus (RAM) species are saprophytic fungi present in environment -transmitted by spore inhalation to cause mucormycosis -Mucomycosis = opportunistic infection -classic clinical picture is paranasal sinus involvement in a diabetic or immunosuppressed patient -the fungi form broad non-septate hyphae that branch at RIGHT ANGLES |
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Hyper-IgM syndrome
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Results from inability of B-lymphocytes to undergo isotope switching from IgM to other Ig isotopes such as IgD/G/E/A.
-results in lymphoid hyperplasia and recurrent sinopulmonary infections. -usually due to genetic absence of the CD-40 ligand on T-lymphocytes, or from a genetic deficiency in the enzymes responsible for the DNA modification that takes place during isotope switching. |
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Conversion of glucose to sorbitol
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-during hyperglycemia, excess plasma glucose is converted to sorbitol by aldose reductase.
-sorbitol accumulates within some cells and attracts water into these tissues --> osmotic cellular injury. -this mechanism is implicated in the pathophysiology of cataracts and peripheral neuropathy in diabetes. |
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Lung zones – ventilation and perfusion
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-perfusion (bloodflow) is much higher in base of lung than in apex
-ventilation is slightly higher in the base than in the apex -therefore, the ventilation/perfusion ratio is higher in the apex than in the base of the lung. |
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Zone 1 of lung
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-does not occur in lung under normal physiologic conditions – when it is present, zone 1 is in apex
-alveolar pressure > arterial pressure > venous pressure --> vessels collapsed -arterial pressure is low because heart must pump blood "uphill" against gravity -since arterial pressure is lower than alveolar pressure, pulmonary capillaries are collapsed and there is no blood flow – i.e., zone 1 represents alveolar dead space. -regions of zone 1 can form when there is lower than normal pulmonary arterial pressure (e.g., with hemorrhage), or higher than normal alveolar pressure (e.g., with positive pressure ventilation). |
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Zone 2 of lung
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-Zone 2 found in higher areas of lung (closer to apex)
-arterial pressure > alveolar pressure > venous pressure -since alveolar pressure is greater than venous pressure, the pulmonary capillaries are initially obstructed near the venous end of the capillary bed. -however, as arterial pressure rises during systole, capillary pressure becomes high enough to overcome alveolar pressure. -therefore, blood flows through zone 2 in a pulsatile fashion |
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Zone 3 of lung
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-zone 3 found in lower areas of the lung
-arterial pressure > venous pressure > alveolar pressure. -since arterial and venous pressures are both greater than alveolar pressure, blood flows continuously through the pulmonary capillaries. -when a person lies supine, the differences in lung perfusion are negated, as gravity then affects the lung equally from apex to base. -in supine individual, lung is ENTIRELY COMPSED OF ZONE 3 blood flow. |
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V/Q ratio
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Although both ventilation and perfusion increase from apex to base, perfusion increases to greater degree
-thus, V/Q ratio progressively decreases from ~2.5 to ~0.6 |
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Superior laryngeal nerve
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-superior laryngeal nerve and recurrent laryngeal nerve are branches off vagus
-superior laryngeal nerve: --internal branch: sensory innervation above vocal cords --external branch: cricothyroid muscle -recurrent laryngeal nerve --innervates all laryngeal muscles except cricothyroid --provides sensory innervation below the vocal cords |
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Aortic rupture
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-aortic rupture most comely caused by motor vehicle accidents
-MVA with sudden deceleration can cause different rates of deceleration between heart (in fixed position and aorta. -most common site of injury is the AORTIC ISTHMUS – the connection between the ascending and descending aorta, distal to where the left subclavian artery branches off the aorta |
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Acetaminophen toxicity
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-can be effectively treated by sulfhydryl group supplementation
-N-acetyl cysteine provides the sulfhydryl groups -NAC also acts as a glutathione substitute – binds toxic metabolite |
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Acetaminophen toxicity cntd.
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-in therapeutic doses, 90% of acetaminophen is metabolized in liver by sulfating and glucuronide conjugation
-remainder eliminated in liver via oxidation by cytochrome-P450 system, and by urinary excretion of un-metabolized drug -metabolite of cytochrome-P450 oxidase pathway is called NAPQI -NAPQI = toxic and highly reactive compound -in therapeutic doses, small about of NAPQI generated – normally metabolized by hepatic glutathione into non-toxic compounds -with acetaminophen TOXICITY, sulfating and glucuronide conjugation in liver are saturated –> excess NAPQI is formed by the cyt-P450 enzymes -with depletion of glutathione, NAPQI is free to interact with the cells, causing hepatocellular injury and centrilobular necrosis |
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-Hypoventilation
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-hypoventilation causes increase in arterial pCO2 and decrease in serum pH (respiratory acidosis)
-acute respiratory acidosis presents with low pH, high pCO2, and normal to mildly increased HCO3- --bicarb not markedly elevated because renal compensation requires at least 24 hours of persistent reparatory acidosis. -vs. chronic respiratory acidosis: --low/normal pH, high pCO2, high HCO3- (greater than 30) |
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Homocystinuria
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-Cysteine becomes an essential amino acid in patients with homocystinuria,
--because the defective enzyme cystathionine synthetase produces the substrate used by cystathionase for the endogenous production of cysteine. -homocystInuria = condition with hyper coagulability and premature atherosclerosis -also ectopia lentis (displaced ocular lens), osteoporosis, mental retardation |
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Nitrites as antidotes
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Nitrites are oxidizing agents – effective in TREATMENT OF CYANIDE POISONING, due to ability to cause methemoglobinemia
-Methemoglobin contains ferric (Fe3+) rather than ferrous (Fe2+) -- like Ferris Beuller, plus his two friends -Cyanide binds to ferric iron more avidly than to mitochondrial cytochrome enzymes, which saves these mitochondrial enzymes from cyanide's toxic effect |
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Cyanide poisoning
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-antidote is nitrites
-presents as rapidly developing cutaneous flushing, tachypnea, headache, tachycarida, with n/v, confusion, and weakness -can progress to respiratory distress and cardiac dysfunction |
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X-linked recessive trait – inheritance by a female
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-Given phenotypically normal parents, the probability that a female sibling of a male affected by an X-linked recessive disease will give birth to an affected child is 1/8.
-Equals probability that sister is a carrier (=0.5) x probability that sister's offspring would inherit the carrier gene assuming she is a carrier (0.5) x probability that sister will have a male child (0.5) 0.5 x 0.5 x 0.5 = 0.125 = 1/8 |
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Mucormycosis (again!)
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-findings of facial pain, headache, and black necrotic eschar (piece of dead tissue) in patient with diabetic ketoacidosis are highly suggestive of mucormycosis.
-Histologic examination of the affected tissue is necessary to confirm the diagnosis. -these fungi (RAM – Rhizopus, Absidia, Mucor) show broad non-septate hyphae with right angle branching. -Treatment consists of surgical debridement and amphotericin B |
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Treatment of Wilson's disease
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-Pathogenesis of Wison's disease (hepatolenticular degeneration) involves excess of non-ceruloplasmin-bound serum copper
--leads to injurious accumulation of copper in liver, CNS lenticular nucleus, and cornea -chelation therapy with PENICILLAMINE is indicated to remove excess loosely bound serum copper |
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Shiga-like toxins
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-Shiga-like toxins (aka, Vero cytotoxins) are produced by EHEC – Eneterohemorrhagic E. coli
-these toxins are nearly identical to the Shiga toxin produced by Shigella dysenteriae -toxins function to INHIBIT THE 60S RIBOSOMAL SUBUNIT in human cells, thereby blocking protein synthesis by preventing binding of tRNA -This mechanism differs from that of diphtheria toxin and exotoxin A of Pseudomonas, as these toxins act on EF-2 (elongation factor 2), rather than the 60S subunit. |
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Absolute risk reduction
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ARR = event rate control – Event rate treatment
Event rate = events/total subjects for example, if ARR = 4%, and event rate control = 6%, then Event rate treatment = 2% --> If events in control group = 24, we can find number of total people in control group 2% = 24/x --> x = 1200 |
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Clavulanic acid
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-Clavulanic acid, sulbactam, and tazobactam are beta-lactamase inhibitors
-administration of clavulanate with amoxicillin expands amoxicillin's spectrum of activity to include strains of beta-lactamase synthesizing bacteria that would be resistant to amoxicillin alone. -i.e., adding clavulanic add to treatment regimen decreases amoicillin cleavage by bacterial cells |
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Peptostreptococci and Fusobacteria in lung abscesses
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-Peptostreptococci and Fusobacteria are anaerobic bacteria that are normally found in oral cavity
-they cause lung abscesses associated with aspiration -risk factors for such abscesses include: alcoholism, seizure disorder, CVA, and dementia |
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Diabetic neuropathy
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-Neuropathy is frequent complication of diabetes mellitus
-caused by diabetic microangiopathy, aka, endoneural arteriole hyalinization, which leads to nerve ischemia -another pathogenetic factor is the accumulation of sorbitol, which leads to osmotic nerve injury. -this can manifest as symmetric peripheral neuropathy |