Uworld28 Flashcards
MOA of bisphosphonates (eg, alendronate, risedronate)
inhibit osteoclast-mediated bone resorption.
They have a chemical structure similar to that of pyrophosphate and attach to hydroxyapatite binding sites on bony surfaces.
Bisphosphonates decrease osteoclast recruitment, reduce bone resorption activity, and induce osteoclast apoptosis.
What is a S3?
low frequency sound occuring during early diastole, just after S2.
Left ventricular gallops (S3 and S4) are best heard with the bell of the stethoscope over the cardiac apex while the patient is in left lateral decubitus position at end expiration.
Niacin is a precursor for?
nicotinamine adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), two important cofactors for many dehydrogenase and reductase enzymes.
Niacin deficiency results in pellagra (ie, diarrhea, dementia, and dermatitis)
Urinalysis in patients with Chlamydia trachomatis infection classically shows?
sterile pyuria (positive urine WBCs, no bacteria on gram stain, no growth on culture) because the C trachomatis bacterium is an obilgate intracellular bacterium with minimal peptidoglycan in its cell wall.
The diagnostic test of choice is nucleic acid amplification testing.
What is an important predictor of insulin resistance?
Visceral obesity as measured by waist circumference or waist to hip ratio.
Which anticoagulants is ideal in pregnancy?
Heparins are ideal anticoagulants for most patients with thromboembolic disease in pregnancy as they do not cross the placenta and therefore the risk of fetal bleeding or teratogenicity is low.
Low molecular weight heparin (eg, enoxaparin) is the preferred therapy, with patients transitioned to unfractionated heparin at term.
Side effect of phenytoin?
Gingival hyperplasia is a common side effect of phenytoin and is sometimes reversible when phenytoin is withdrawn.
Phenytoin causes increased expression of platelet-derived growth factor (PDGF).
When gingival macrophages are exposed to increased amounts of PGDF, they stimulate proliferation of gingival cells and alveolar bone.
Phenytoin toxicity mainly affects the cerebellum and vestibular system, causing ataxia and nystagmus.
What is methadone?
a potent, long acting opioid agonist used in the maintenance treatment of opioid use disorder.
Its prolonged effects suppress withdrawal symptoms and cravings.
What is graves disease caused by?
an autoimmune disorder triggered by thyrotopin receptor antibodies (TRAb) that bind and activate the TSH receptor.
Serum TRAb immunoassays have a high sensitivity and specificity for Graves disease.
What is porcelain gallbladder?
a potential manifestation of chronic cholecystitis and is often found in assoication with multiple gallstones.
It is due to dystrophic intramural deposition of calcium salts in the setting of chronic inflammation.
Porcelain gallbladder is associated with an increased risk of adenocarcinoma of the gallbladder.
What is persistent depressive disorder (ie, dysthymia)?
characterized by chronic depressed mood and accompanying depressive symptoms lasting for >2 years.
It can often be differentiated from major depressive disorder by the number of concurrent depressive symptoms (eg, >5 needed for major depression)
What is osteosarcoma?
most common primary bone malignnacy in children and young adults.
It occurs most frequently at the metaphyses of long bones and presents with local pain and swelling.
Most cases are associated with sporadic or inherited mutations in RB1 (hereditary retinoblastoma) and TP53 (Li-Fraumeni syndrome).
MOA of colchicine
used for treatment of acute gouty arthritis in patients who cannot take nonsteroidal anti-inflammatory drugs.
It inhibits leukocyte migration and phagocytosis by blocking tubulin polymerization.
Significant side effects of colchicine include nausea and diarrhea.
What are the cardiovascular manifestations of lupus?
accelerated atherosclerosis, small vessel necrotizing vasculitis, pericarditis, and Libman-Sacks endocarditis (small, sterile vegetations on both sides of the valve)
What are the renal manifestations in lupus?
diffuse proliferative glomerulonephritis, which is characterized by diffuse thickening of the glomerular capillary walls with “wire loop” structures on light microscopy.
Viral bronchioliits is most commonly caused by?
respiratory syncytial virus and presents with low grade fever, cough, and respiratory distress (eg, tachypnea, retractions) in children age <2 years.
Examination typically shows diffuse wheezes and/or crackles.
Anal squamous cell carcinoma is stronly associated with?
human papillomavirus and typically presents with rectal bleeding, pruritus, and/or pain.
Examination demonstrates an ulcerated or nodular, exophytic anal lesion.
Histo: large, eosinophilic, hyperchromatic squamous cells arranged in islands with nuclear atypia and prominent keratinization
The primary anti-ischemic effect of nitrates is mediated by?
Sublingual nitroglycerin is used for rapid symptom relief in patients with stable angina.
The primary anti-ischemic effect of nitrates is mediated by venodilation causing a decrease in left ventricular end-diastolic volume and wall stress, resulting in decreased myocardial oxygen demand.
What is the criteria for Hardy-Weinberg equilibrium?
A population is in Hardy-Weinberg equilibrium when the frequency of alleles at a particular locus remains constant over successive generations within that population.
To satisfy all criteria for the equilibrium, there must be a large population size, random mating, no natural selection, no migration, and no spontaneous mutations.
Reduced ventricular compliance is seen with?
restrictive cardiomyopathy and other causes of diastolic dysfunction and heart failure with preserved ejection fraction (eg, hypertensive heart disease).
It involves ventricular wall thickening and/or stiffening that leads to increased diastolic filling pressure at any given ventricular volume.
Well-differentiated neuroendocrine tumors (ie, carcinoid tumors) arise from?
neuroendocrine cells and are composed of uniform tumor cells with round nuclei, salt and pepper chromatin, and eosinophilic cytoplasm.
Although most are found incidentally (ie, asymptomatic), some may obstruct the lumen, causing acute appendicitis.
What is acute tubular necrosis?
characterized by tubular injury due to renal ischemia or direct cytotoxicity.
The course of the disease takes place in 3 stages: initiation (initial insult), maintenance (oliguric renal failure), and recovery.
During the recovery stage, glomerular filtration rate improves prior to restoration of renal tubular resorptive capacity, so transient polyuria and electrolyte wasting (eg, hypokalemia) can occur.
Function of atrial natriuretic peptide and brain natriuretic peptide
Atrial natriuretic peptide and brain natriuretic peptide are released from the atria and ventricles, respectively, in response to myocardial wall stretch due to intravascular volume expansion.
These endogenous hormones promote increased glomerular filtration rate, natriuresis, and diuresis.
What is Whipple disease?
Whipple disease, caused by the gram+ actinomycete Tropheryma whipplei, is a rare systemic illness that often involves the small intestine, joints, and CNS.
Classic intestinal histo findings include foamy macrophages in the lamina propria with bacilli positive for periodic acid-Schiff stain.
Treatment is with antibiotics.
What are the traits for hep b virus
Hep B virus has a partially double-stranded DNA genome and contains a viral DNA polymerase with reverese transcriptase activity.
Reverse transcriptase serves as a crucial step in viral replication; it converts transcribed positive sense single stranged RNA into the partially dsDNA genome of viral progeny.
Pneumococcal meningitis is associated with?
massive cerebrospinal fluid inflammatory cytokine release in response to bacterial cell wall components.
Treatment with dexamethasone prior to antibiotic therapy has been shown to reduce inflammation and decrease the risk of adverse outcomes (eg, seizures, focal neurologic deficits) and death.
Other forms of bacterial meningitis do not seem to benefit from glucocorticoid treatment.
What is serum sickness?
type III HSR to nonhuman proteins characterized by vasculitis resulting from tissue deposition of circulating immune complexes.
Clinical findings: fever, pruritic skin rash, arthralgias, and low serum C3 and C4 complement levels.
What is seen in 5alpha reductase deficiency?
The enzyme 5-alpha reductase converts testosterone to dihydrotestosterone, which drives development of external male genitalia.
Genotypic males (XY) with 5-alpha reductase def develop female external genitatlia but have internal male genital ducts (eg, vas deferens) instead of internal female genital ducts (eg, uterus)
What is hereditary hemochromatosis?
characterized by excessive intestinal iron absorption with deposition of iron in parenchymal tissues.
Cardiac manifestations include diastolic dysfunction (initial), dilated cardiomyopathy (later) and conduction system disease (eg, sinus node dysfunction)
What is actinic keratoses?
small (usually <1cm), erythematous epidermal lesions with adherent scale that are the result of chronic sun exposure.
Histo: keratinocyte atypia, hyperkeratosis, and parakeratosis.
A small percentage of actinic keratoses progress to invasive squamous cell carcinoma, therefore, frequent monitoring is necessary
Function of small nuclear ribonucleoproteins (snRNPs)
snRNPs are important components of the spliceosome, a molecule which removes introns from pre-mRNA during processing within the nucleus.
Spinal muscular atrophy is a disorder caused by mutations in the SMN1 gene, resulting in impaired assembly of snRNPs in lower motor neurons. Infants often have flaccid paralysis due to degeneration of anterior horn cells in the spinal cord.
The best and most reliable auscultatory indicatory of the degree of mitral stenosis is?
the A2-OS interval. A shorter intercal indicates more severe stenosis.
Other findings can include a diastolic rumbling murmura with presystolic accentuation due to left-atrial contraction.
Sickle cell disease is due to?
the result of a missense mutation in which valine replaces glutamate in the hemoglobin beta-globin chain.
This occurs due to a single nucleotide substitution in DNA, specifically GAG –> GTG
What is the flow of pleural fluid?
Pleural fluid normally enters the pleural space via filtration from the systemic circulation, primarily from the intercostal microvessels of the parietal pleura, and exists the pleural space via stomata in the parietal pleura that drain into the parietal pleura lymphatics.
What causes black pigment stones?
Black pigment stones arise from conditions that increase the amount of unconjugated bilirubin in bile, which promotes calcium bilirubinate precipitation.
This may occur in the setting of chronic hemolysis (eg, sickle cell anemia, beta-thalassemia, hereditary spherocytosis) and increased enterohepatic cycling of bilirubin (eg, ileal disease)
What is conjugation?
Conjugation is a form of horizontal gene transfer that involves the formation of a pilus and the direct passing of genetic material from one bacterium to another.
It is a common source of antibiotic resistance and environmental adaptation.
The other forms of bacterial horizontal gene transfer are transduction (viral vector) and transformation (uptake of free DNA).
What is cytochrome c?
Cytochrome c is a mitochondiral enzyme that activates caspases and indirectly brings about cell death through intrinsic pathway apoptosis.
What is primary (psychogenic) polydipsia?
characterized by excessive intake of free water, leading to hyponatremia and production of larege volumes of dilute urine.
Water restriction normalizes serum sodium levels and increases urine osmolality.
Nonalcoholic fatty liver disease?
frequently develops in patients with metabolic syndrome (eg, obesity, dyslipidemia, insulin resistance) and can progress to cirrhosis due to chroic inflammation and hepatocyte injury.
What is Chagas disease?
caused by a chronic infection by Trypanosoma cruzi and causes secondary achalasia due to destruction of the submucosal (Meissner) and myenteric (Auerbach) plexus.
Other manifestations can include nonischemic cardiomyopathy and megacolon.
What is absolute risk reduction?
the difference in event rate between a control group and a treatment group (ie, the percentage of patients improved by treatment)
ARR= control rate - treatment rate
What is classical conditioning?
involves a neutral stimulus being repeatendly paired with a non-neutral stimulus that elicits a reflexive, unconditioned response.
Over time, the formerly neutral stimulus is able to evoke a conditioned response by itself in absence of the non-neutral stimulus.
What is the classic triad of opioid intoxication?
decreased respiratory rate, pupillary constriction (ie, miosis) and depressed mental status.
Hypothermia, hypotension, and decreased tidal volume are also common findings.
What is seen in beta blocker toxicity?
Beta blockers act as competitive antagonists for endogenous catecholamines; therefore, toxicity presents with hypotension, bradycardia, bronchospasm, and hypoglycemia.
The hypotension and hypoglycemia contribute to altered mental status.
The airway resistance at each level of the lower respiratory tract is inversely related to?
the total cross-sectional area of all the airways at that level.
Airway resistance is high in the trachea and reached a peak in the medium sized bronchi, where total cross-sectional area ia at a minimum.
Airway resistance then progressively decreases as total cross-sectional area increases through the smaller bronchioles, terminal bronchioles, and alveoli.
What is hypersensitivity pneumonitis?
results from an exaggerated immunologic response to an inhaled antigen (eg, mold, animal protein), and presents with cough and dysnpea of variable acuity.
Bronchoalveolar lavage typically shows high relative lymphocyte count (eg, >20%), which helps support the diagnosis.
Sensation to the parietal pleura, chest wall, and skin of the chest is supplied by?
the intercostal nerves that derive from the ventral nerve rami
A nerve block can be used to control pain from these areas when opioids are ineffective, contraindicated, or have intolerable adverse effects.
What causes anisocoria (asymmetric pupils)?
caused by a lesion in the ocular parasympathetic (constriction) or sympathetic (dilation) pathways.
In this patient, aniscocria increases in bright light, indicating that the larger right pupil is unable to constrict due to a defect in the right parasympathetic pathway.
Pulmonary infection (eg, community-acquired pneumonia, tuberculosis) causes pleural effusion primarily via?
an inflammatory increase in vascular and pleural membrane permeability.
Such effusions are exudative by Light criteria, typically with relatively high pleural fluid protein and lactate dehydrogenase concentrations.
Tuberculosis pleural effusions typically demonstrate a lymphocyte-predominant leukocyte pattern.
The lac operon is regulated by?
two distinct mechanisms: negatively by binding of the repressor protein to the operator locus and positively by cAMP-CAP binding upstream from the promoter region.
Constitutive expression of the structural genes of the lac operon occurs with mutations that impair the binding of the repressor protein (Lac I) to its regulatory sequence in the operator region.
What is the pathogenesis of allergic contact dermatitis?
a delayed-type HSR. Initially, Langerhans cells travel to regional lymph nodes and present haptens to naive T cells, leading to clonal expansion.
On reexposure to the hapten, sensitized T cells cause tissue destruction that manifests as pruritic erythema, vesicles, and/or bullae 2-3 days after exposure.
An abnormal alpha-fetoprotein level is most commonly due to?
a dating error (eg, inaccurate gestational age).
The maternal serum quadruple screen assesses for risk of congenital defects and fetal aneuploidy and includes measurement of alpha-fetoprotein levels, which are dependent on gestational age.
alpha fetoprotein is decreased in Down syndrome and Edwards (trisomy 18)
What is Reye syndrome?
characterized by liver failure and encephalopathy following salicylate (aspirin) administration in children with a febrile illness.
Aspirin induced mitochondrial dysfunction causes impaired fatty acid metabolism and microvesicular steatosis of the liver.
What is West Nile virus?
single stranded flavivirus transmitted by mosquitoes, most commonly in the summer.
Most infections are asymptomatic or may present with a flu-like illness (West Nile fever), often with a maculopapular or morbilliform rash.
Neuroinvasive disease manifests as meningitis, encephalitis, or asymmetric flaccid paralysis; patients may have parkinsonian features (eg, tremor)
Fludrocortisone improves hypovolemia and orthostatic hypotension in primary adrenal insufficiency by?
decreasing urine sodium excretion (thereby increasing circulating blood volume) and increasing the sensitivity of the vasculature to endogenous vasoconstrictors (eg, norepinephrine)
Where does antidiuretic hormone act in the nephron?
ADH acts on the medullary segment of the collecting duct to increase urea and water reabsorption, allowing for the production of maximally concentrated urine.
What is a prospective cohort study?
organized by selecting a group of people (ie, cohort) determining their exposure status, and then following them over time for development of the disease of interest.
Increases in resting blood flow to ischemic myocardium are primarily mediated by?
locally-acting substances (eg, adenosine, nitric oxide) that trigger coronary arteriolar vasodilation.
Pharmacologic arteriolar vasodilatorys (eg, adenosine, dipyridamole) mimic the vasodilation that occurs with exercise and may cause redistribution of blood flow from ischemic to nonischemic areas of myocardium (ie, coronary steal).
MOA of isoniazid
an antimycobacterial agent that specifically inhibits the synthesis of mycolic acids, which are essential components of the mycobacterial peptidoglycan cell wall.
Without mycolic acids, the mycobacateria lose their acid-fastness and become unable to synthesize new cell walls or multiply.
What is orotic aciduria?
a rare AR disorder of de novo pyrimidine synthesis that occurs due to a defect in uridine 5’-monophosphate (UMP) synthase.
Children typically present with developmental delay, megaloblastic anemia, and large amounts of urinary orotic acid.
Uridine supplementation can improve symptoms as uridine is converted to UMP via nucleoside kinases.
What is Osgood-Schlatter disease?
The quadriceps muscle group is connected to the patella, which is attached to the tibial tubercle by the patellar ligament.
Repetitive quadriceps contraction (eg, jumping) in adolescents can result in Osgood-Schlatter disease, which is characterized by focal anterior knee pain and swelling due to chronic avulsion of the tibial tubercle.
Oral leukoplakia can lead to?
Oral leukoplakia is a potentially premalignant lesion; the risk for progression to invasive carcinoma is related to the degree of dysplasia.
What is aplastic anemia?
bone marrow failure due to multipotent hematopoietic stem cell destruction.
Cases are often triggered by meds, radiation, toxins, or viruses,
Meds-induced AA can be due to dose-dependent bone marrow damage (eg, chemotherapy, immunosuppressive drugs) or idiosyncratic reactions (eg, antiseizure meds, sulfonamides, nifedipine) that may occur at any point during or after therapy.
What is food protein induced allergic proctocolitis?
non IgE mediated reaction that causes inflammation and eosinophilic infiltration of the distal colon.
Classic presentation is in early infancy with painless, blood streaked stools that resolve with dietary avoidance of the offending food protein (eg, cow’s milk)
What is osmotic demyelination syndrome?
results from overly rapid correction of chronic hyponatremia.
Clinical features: quadriplegia, pseudobulbar palsy, and reduced level of consciousness.
MRI: focal demyelination of the pons
Active tuberculosis is never treated with drug monotherapy due to?
the fast emergence of mycobacterial antibiotic resistance from rapid, selective gene mutations.
Isoniazid monotherapy may be used for patients who have a positive PPD and a negative chest x-ray (ie, no evidence of clinical disease)
What is specificity?
the number of true negatives divivded by the total number of subjects confirmed as not having the disease
TN = (specificity)*(number of patients confirmed without the disease)
FP= (1-specificity)*(number of patients confirmed without the disease)
Drug dosing regimens with more frequent dosing have what effects?
lower peak and average drug levels, which can help reduce toxicity.
What is relative risk reduction and formula?
measures how much a treatment reduces the risk of an unfavorable outcome.
Two methods to calculate it are:
RRR= (Riskcontrol - Risktreatment)/ Riskcontrol
RRR= 1- relative risk
Abscess formation is largely driven by?
neutrophil recruitment and activation leading to the release of cytotoxic granules that kill bacteria but also cause liquefying necrosis of surrounding tissue.
What is sciatic neuropathy?
a common complication of hip fracture and/or arthroplasty because of the proximity of the sciatic nerve to the hip joint.
Injury to the sciatic nerve in the pelvis causes neurological deficits across the sciatic nerve (knee flexion), common peroneal nerve (dorsiflexion, numbness of the calf and dorsal foot), and tibial nerve (plantar flexion, ankle reflex)
The metanephric blastema gives rise to?
glomeruli, Bowman space, proximal tubules, loop of Henle, and distal convoluted tubules.
The ureteric bud gives rise to?
the collecting system of the kidney (eg, collecting tubules and ducts, major and minor calyces, renal pelvis, ureters)
What is respiratory distress syndrome?
classically presents in premature infants with increased work of breathing and hypoxia at birth due to surfactant deficiency.
Poor alveolar compliance leads to widespread atelectasis and decreased functional residual capacity.
Airway resistance is often increased due to lung inflammation and edema.
What is hemolytic uremic syndrome?
Enterohemorrhagic E colic is primarily contracted after eating undercooked ground beef.
EHEC produces Shiga toxin, which causes hemorrhagic colitis and can lead to hemolytic-uremic syndrome.
HUS is characterized by acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia; children age <10 are at greatest risk.
What is Hirschsprung disease?
characterized by absent submucosal and myenteric ganglion cells in the distal colon.
Contrast enema classically shows a narrowed aganglionic segment (most commonly rectosignmoid) with an abrupt transition zone to the dilated, histologically normal proximal colon.
What is analgesic nephropathy?
a form of chronic kidney disease caused by prolonged, heavy intake of nonsteroidal anti-inflammatory drugs and/or acetaminophen.
Pathologic characteristics include chronic interstitial nephritis and papillary necrosis.
What is akathisia?
an extrapyramidal side effect of antipsychotic medication characterized by inner restlessness and an inability to sit or stand in one position.
Treatment involves a reduction in the antipsychotic dose, if possible, or the addition of a beta blocker or benzodiazepine.
What is REM sleep behavior disorder?
a parasomnia characterized by dream-enactment behaviors due to a loss of atonia during REM sleep.
Most patients with idiopathic RBD eventually develop a disorder of alpha-synuclein neurodegeneration, most commonly Parkinson disease,
Aortic compliance progressively decreases with age, especially in those >65. This leads to?
an increase in pulse pressure, a slight decrease in diastolic pressure, and the characteristic isolated systolic hypertension commonly seen in the elderly population.
What is the most common congenital anomaly associated with Down syndrome?
A complete atrioventricular (AV) canal defect is comprosed of an atrial septal defect, a ventricular septal defect, and a common AV valve.
Vibrio cholerae and enterotoxigenic Escherichia coli cause a purely toxin-mediated watery diarrhea. What is seen on stool microscopy?
The toxins secreted by these organism modify electrolyte handling by enterocytes but do not cause cell death; therefore, no erythrocytes or leukocytes are typically noted on stool microscopy.
IgE-binding monoclonal antibodies (eg, omalizumab) MOA
IgE-binding monoclonal antibodies (eg, omalizumab) are effective in treating asthma that remains uncontrolled despite optimal therapy with bronchodialtors and inhaled corticosteroids.
IgE binding monoclonal antibodies reduce airway inflammation by blocking the binding of IgE to the IgE receptors on mast cells and preventing the release of proinflammatory substances, including histamine and leukotrienes.
Patients on warfarin who take antibiotics that target gram-negative microorganisms (eg, metronidazole, macrolides, fluroquinolones) can develop supratherapeutic INR due to?
disruption of vitamin-K producing intestinal flora.
Why are tumors with defective DNA mismatch repair dependent on adaptations to avoid cytotixic T-cell destruction?
Because tumors with defective DNA mismatch repair generate high levels of neoatntigens, they are particularly dependent on adaptations (eg, overexpression of immune checkpoints) to avoid cytotoxic T cell destruction.
Treatment with immune checkpoint inhibitors restore anti tumor cytotoxic T cell activity and often dramatically reduce tumor burden.
Polymerase chain reaction is used to?
Polymerase chain reaction is used to amplify small fragments of DNA (eg, genes, exons, noncoding regions) by repeated replication.
It requires primers that are complementary to the regions of DNA flanking the segment of interest.
Thermostable DNA polymerase, deoxynucleotide triphosphates, and a source DNA template strand are also necessary.
Function of the posterior cruciate ligament
The posterior cruciate ligament attaches proximally to the medial femoral condyle (anterolateral surface) and distally to the posterior aspect of the intercondylar area of the tibia.
It prevents posterior displacement of the tibia relative to the femur when the knee is flexed.
What is seen in cardiogenic shock?
Myocardial infarction may be complicated by acute left ventricular failure and cardiogenic shock.
In cardiogenic shock, increased LV end diastolic pressure is transmitted backward to cause increased pulmonary capillary wedge pressure (evidenced by pulmonary edema) and increased central venous pressure.
There is markedly decreased cardiac output, which causes hypotension and decreased coronary perfusion pressure.
What are some factors that promote edema?
Peripheral edema results from the accumulation of fluid in the interstitial spaces.
Factors that promote edema include elevated capillary hydrostatic pressure, decreased plasma oncotic pressure, and impaired lymphatic drainage.
In chronic heart failure, increased lymphatic drainage initially offsets factors favoring edema, temporarily delaying edema development.
What is acute tubular necrosis?
characterized by focal tubular epithelial necrosis with denuding of the basement membrane.
Most patients experience tubular re-epithelization and regain normal renal function.
How does beta blockers affect ECG?
Beta blockers decrease AV nodal conduction, leading to an increased AV nodal refractory period.
This correleates to PR interval prolongation on ECG.
How does Hep B and D work together to infection?
The hep B surface antigen of hep B virus must coat the hep D antigen of hep D virus before it can infect hepatocytes and multiply.
Presbyopia occurs due to?
Presbyopia and skin wrinkles are age related changes.
Presbyopia occurs due to denaturation of structural proteins within the lens, leading to loss of lens elasticity which can result in improved vision in patients with mild myopia. Decreased synthesis and increased breakdown of collagen and elastin contribute to the development of skin wrinkles.
Deficiency of 21-hydroxylase causes?
adrenal cortical hyperplasia due to excess of the adrenal cortex by ACTH.
The classic, non salt wasting form presents in boys age 2-4 with early virilization, accelerated linear growth, and elevated levels of 17-hydroxyprogesterone and androgens
What is the treatment of congenital adrenal hyperplasia due to 21-hydroxylase deficiency?
low doses of exogenous corticosteroids to suppress excess ACTH secretion, which reduces production of androgens by the adrenal cortex.
What can cause pulmonary hypertension?
Advances hypoxic lund disease (eg, chronic obstructive pulmonary disease, interstitial lung disease, obesity hypoventilation syndrome) is a common cause of pulmonary hypertension (ie, increased right ventricular afterload).
The increase in pulmonary arterial pressure mainly results from chronic and diffuse hypoxic vasoconstriction, with a lesser degree of vascular remodeling than in (primary) pulmonary arterial hypertension.
What structures can be injured during pelvic surgery?
The ureters run in close proximity to the pelvic lymph nodes and the uterine artery in the female pelvis, which predisposes them to injury during pelvic surgery.
What is the hallmark of neurofibromatosis type 2?
Bilateral vestibular schwannomas.
NF2 is a dominantly inherited disorder caused by mutations of the NF2 gene on chromosome 22.
Early onset familial Alzheimer disease is assicated with which gene mutations?
APP (ch.21), presenilin 1 and presenilin 2
