Uworld22 Flashcards
MOA of physostigmine?
a cholinesterase inhibitor with a tertiary ammonium structure that can reverse both the central and peripheral nervous system symptoms of anticholinergic toxicity.
Neostigmine, edrophonium, and pyridostigmine have a quaternary ammonium structure that limits central nervous system penetration.
How can Vitamin B12 deficiency cause neurologic damage?
Neurologic damage associated with vitamin B12 def classically includes subacute combined degeneration of the dorsal columns (loss of position and vibration sensation, positive Romberg sign) and lateral corticospinal tracts (muscle weakness, spastic paresis)
What is acute cholangitis?
a life threatening infection characterized by fever, right upper quadrant pain, and jaundice (Charcot triad); hypotension and altered mental status (Reynold pentad) occur in severe cases.
Acute cholangitis typically develops in the setting of biliary obstruction; common etiologies include gallstone, malignancy, and strictures.
Dilated cardiomyopathy results from?
direct damage to cardiomyocytes and consequent myocardial contractile dysfunction (systolic dysfunction), volume overload, and ventricular dilation.
Viral myocarditis is a potential cause of dilated cardiomyopathy and should be suspected in young patients who develop heart failure following a viral prodrome.
Some patients with nonsmall cell lung carcinoma harbor a chromosomal rearrangement that creates a fusion gene between?
EML4 (echinoderm microtubule associated protein like 4) and ALK (anaplastic lymphoma kinase). This results in a constitutive active tyrosine kinase that causes malignancy.
This pathophysiology is similar to chronic myeloid leukemia
MOA of zidovudine
a nucleoside reverse transcriptase inhibitor used to prevent maternal to fetal transmission of HIV during labor (when the mother is not virally suppressed).
It is a thymidine analogue that does not have the normal 3’hydroxyl group found on thymidine. Because new nucleotides are added to growing DNA chains only at the 3’hydroxyl group, the addition of ZDV into DNA results in chain termination.
What is pill esophagitis?
can be caused by tetracyclines (doxycycline), results from prolonged contact of caustic medication with the esophageal mucosa. It most often occurs in locations where the esophagus is in close proximity to other anatomic structures, such as where the proximal esophagus comes in contact with the aortic arch and the carina.
What is hemolytic uremic syndrome?
manifests with acute kidney injury, microangiopathic hemloyic anemia, and thrombocytopenia.
Labs: decreased hemoglobin and platelet count and increased bleeding time, lactate dehydrogenase, bilirubin, blood urea nitrogen, and creatinine.
Parvovirus B19 can cause what?
causes erythema infectiousum (fifth disease) in children and arthritis in adults.
Parvo arthritis can mimic rheumatoid arthritis but is usually self-resolving
What can trigger IgE-independent mast cell degranulation?
A number of meds, inclduing opiods, radiocontrast agents, and some antibiotics (eg, vancomycin), can trigger IgE independent mast cell degranulation.
Common symptoms include diffuse itching and pain, bronchospasm, and localized swelling (urticaria)
What is potter sequence?
results from a urinary tract anomaly (eg, bilateral renal genesis) that causes decreased fetal urine output and severe oligohydraminos. The lack of amniotic fluid causes increased fetal compression (eg, flat facies, limb deformity) and pulmonary hypoplasia (eg, neonatal hypoxia), which is the most common cause of death in affected neonates.
What is anticipation?
describes an inherited condition that presents earlier and with more severe disease in successive generations.
In myotonic dystrophy, increasing length of the pathogenic trinucleotide repeat expansion accounts for severe hypotonia in a neonate (congenital) and mild symptoms (eg, myotonia, facial weakness) in parent (classic [adult]).
What is rabies virus?
has a bullet shaped envelope with knob-like glycoproteins that bind to nicotinic acetylcholine receptors.
Once transmission occurs (usually due to a bite wound from an infected animal), the virus replicates locally in muscle tissue for several days or weeks before spreading in a retrograde fashion through the peripheral nerve axons to the central nervous system.
MOA of thiazolidinediones?
activate peroxisome proliferator activated receptor gamma, a nuclear receptor that alters the transcription of genes involved in glucose and lipid metabolism.
The resulting decrease in insulin resistance lowers blood glucose and can help reverse nonalcoholic steatohepatitis.
What are some common complications of psoriasis?
psoriatic arthritis, nail changes, and uveitis
An orbital floor fracture can result in?
entrapment of the inferior rectus muscle, which presents with vertical diplopia and restriction of upward movement.
In addition, the infraorbital nerve (a branch of V2) runs along the orbital floor and can be damaged, resulting in numbness and paresthesia of the upper cheek, lip, and gingiva.
How can patients with CKD and diabetes have hypoglycemia?
Insulin has both renal and hepatic clearance. In patients with advanced chronic kidney disease and diabetes mellitus, decreased renal clearance of insulin can lead to symptomatic hypoglycemia if exogenous insulin doses are not adjusted based on the change in renal function.
What is atrioventricular nodal reentrant tachycardia?
the most common type of paroxysmal supraventricular tachycardia, resulting from abnormal conduction through 2 distinct atrioventricular nodal pathways.
ECG: narrow QRS complex tachycardia with a regular rhythm and buried (not visible) P waves.
Which lymph node enlargement is concerning for malignancy?
Lymph node enlargement is most commonly due to infection-triggered cellular proliferation but can be caused by clonal expansion of malignant cells.
Enlargement of the supraclavicular lymph nodes, which drain the chest and abdomen, is unlikely to be caused by common childhood infections and is concerning for malignancy
Irreversible ischemic injury to brain tissues causes?
causes tissue digestion by hydrolytic enzymes (liquefactive necrosis). The infarcted CNS tissue is eventually replaced with a cystic astroglial scar. In other organs, lethal ischemic injury results in coagulative necrosis
A lesion in Wernicke’s area can cause?
receptive aphasia, which is characterized by well articulated, nonsensical speech paired with a lack of language comprehension (Wernicke-Word salad).
Wernicke’s area is located in the auditory association cortex within the posterior portion of the superior temporal gyrus in the dominant temporal lobe.
The middle cerebral artery supplies Broca’s area (superior division) and Wernicke’s area (inferior division)
What is exogenous thyrotoxicosis?
can be caused by suppressive levothyroxine therapy for thyroid cancer.
When exogenous thyrotoxicosis is due to levothyroxine or mixed T3/T4 supplements, thyroxine (T4) levels are elevated; triiodothyronine (T3) is produced primarily by the peripheral deiodination of T4, so T3 levels also are elevated even if the patient is taking T4 only.
What is hemoglobin C?
caused by a missense mutation that results in a glutamate residue being substituted by lysine in the beta globin chain.
This results in an overall decrease in negative charge for the hemoglobin molecule. The speed of hemoglobin movement during gel electrophoresis is hemoglobin A > hemoglobin S > hemoglobin C
what is nocardia?
a filamentous, branching, gram+, bacteria that is partially acid fast. It most commonly causes pneumonia and brain abscesses in immunocompromised patients
The optimal site for obtaining vascular access in the lower extremity during cardiac catheterization is?
the common femoral artery below the inguinal ligament. Cannulation above the inguinal ligament can significantly increase the risk of retroperitoneal hemorrhage.
Sodium glucose cotransporter 2 inhibitors MOA
decrease renal reabsorption of glucose and sodium, leading to increased urinary glucose excretion and decreased blood glucose levels.
In addition, natriuresis and osmotic diuresis lead to a small decrease in extracellular fluid volume, total body sodium content, and blood pressure.
Side effects of spironolactone
Spironolactone is an aldosterone antagonist commonly used to treat heart failure.
It has significant antiandrogenic effects and can cause gynecomastia, decreased libido, and impotence.
Eplerenone is a more selective aldosterone antagonist with fewer adverse effects
What is an aortic dissection?
Aortic dissection classically presents with severe retrosternal pain that radiates to the back. This condition develops when overwhelming hemodyanmic stress leads to tearing of the aortic intima with blood subsequently dissecting through the aortic media.
The resulting intramural hematoma can extend both proximally and distally and can compress major arterial branches and impair blood flow.
What is carotid sinus hypersensitivity?
most commonly seen in elderly men and involves an exaggerated vasovagal response to tactile stimulation of carotid sinus baroreceptors (eg, adjusting a shirt collar or necktie).
The resulting increase in parasympathetic output leads to a prolonged sinus pause that contributes to the excessive drop in blood pressure, leading to transient loss of cerebral perfusion that manifests as presyncope (eg, lightheadedness) or syncope
what are type I muscle fibers (slow twitch or red fibers)?
primarily use oxidative phosphorylation and contain high quantities of lipids, myoglobin, and mitochondria.
They are specialized in sustained, low force contraction, and their function is amplified by endurance training.
What are type II muscle fibers (fast twitch or white fibers)?
primarily use glycolysis and specialize in rapid bursts of high force contraction. Their function is amplified by resistance training.
What is polycythemia vera?
a clonal myeloproliferative disease characterized by an increased RBC mass and low erythropoietin levels.
The majority of patients with PV have a JAK2 mutation causing hematopoietic stem cells to proliferate uncontrollably.
How can polycythemia vera be differentiated from secondary polycythemia?
by the presence of leukocytosis, thrombocytosis, and/or splenomegaly.
What is the primary pathogenic mechanism for Shigella infection?
Shigella is a non-lactose fermenting organism that does not produce hydrogen sulfide on triple sugar iron agar.
Mucosal invasion is the primary pathogenic mechanism for Shigella infection, which presents with bloody/mucoid diarrhea.
How does chronic hypertension result in hypertensive nephrosclerosis?
Chronic hypertension can result in hypertensive nephrosclerosis, which is characterized by compensatory medial hypertrophy and fibrointimal proliferation; endothelial damage from elevated systemic pressure also leads to hyaline arteriolosclerosis.
The narrowed arteriolar lumens cause a progressive decrease in renal blood flow, resulting in glomerular ischemia and fibrosis (glomerulosclerosis)
What can be used to treat both BPH and hypertension?
Alpha-1 blockers such as doxazosin, prazosin, and terazosin are useful for the treatment of both benign prostatic hyperplasia and hypertension.
To minimize adverse effects and drug interactions, it is desirable to prescribe a medication that can address multiple issues at once.
Phenytoin metabolism depends on the function of?
hepatic P450 oxidases and is dose dependent. Drugs that induce hepatic microsomal enzymes (phenobarbital, carbamazepine, and rifampin) enhance phenytoin metabolism and decrease its serum concentraion.
What is the virulence factor of strep pneumo? ?
primarily due to a polysaccharide capsule.
A conjugate vaccine provides long lasting immunity against serotypes in the vaccine but provides no significant immunity against nonvaccinated serotypes.
Therefore, infection can still occur due to serotypes not covered by the vaccine.
What is kaposi sarcoma?
Kaposi sarcoma often presents as multiple red, purple, or brown lesions on the lower extremities in patients with HIV infection. It is a vascular tumor caused by human herpesvirus type 8 infection of endothelial cells.
What is preeclampsia?
new onset hypertension (systolic >140 or diastolic >90) with proteinuria and/or signs of end organ damage (eg, renal insufficiency).
Preeclampsia is associated with widespread maternal endothelial dysfunction, which occurs due to increased antiangiogenic factor release and decreased proangiogenic factor activity (eg, vascular endothelial growth factor)
MOA of calcium channel blockers
inhibit the L-type calcum channel on vascular smooth muscle and cardiac cells.
Dihydropyridines (eg, nifedipine, amlodipine) primarily affect peripheral arteries and cause vasodilation.
Nondihydropyridines (eg, verapamil, diltiazem) affect the myocardium and can cause bradycardia and slowed atrioventricular conduction.
What is short bowel syndrome?
typically occurs in patients with massive small bowel resection and/or Crohn disease due to loss of intestinal absorptive surface area and a decrease in intestinal transit time.
Patients usually present with postpranial voluminous diarrhea and weight loss due to malabsorption. Loss of functional distal ileum may result in vitamin B12 def.
What is the most common type of thyroid cancer?
Papillary thyroid carcinoma. Characteristic microscopic features include large cells with nuclei containing finely dispersed chromatin, giving them an empty or ground glass appearance (ie, Orphan Annie eyes), and intranuclear inclusions and nuclear grooves
What can cause a dilated coronary sinus?
The coronary sinus communicates freely with the right atrium and will become dilated secondary to any factor that causes increased right atrial pressure. The most common cause is pulmonary hypertension, leading to elevated right heart pressures
What is a cluster headache?
often present with rapid-onset, severe, unilateral pain accompanied by ipsilateral autonomic symptoms (eg, ptosis, miosis, nasal congestion, conjunctival injection.
What does Howell-Jolly bodies on peripheral smear represent?
splenic dysfunction, which occurs in sickle cell disease due to recurrent infarction of the splenic vasculature.
Functional asplenia increases the risk of invasive infection with encapsalted organisms.
A normal bleeding time indicates?
adequate platelet hemostatic function.
A normal activated partial thromboplastin time (aPTT) indicates?
an intact intrinscic coagulation system.
Prolonged prothrombin time in the setting of a normal aPTT indicates?
a defect in the extrinsic coagulation system at a step that is not shared with the intrinsic system
What are transporter associated antigen processing (TAP) proteins?
TAP proteins are necessary for loading of cytoplasmic (eg, viral) proteins onto major histocompatibility complex (MCH) class I molecules.
The MHC class I peptide complex can then activate CD8 cytotoxic T cells through interaction with the T cell receptor and CD8 coreceptor
What is 5alpha-reductase deficiency?
5alpha-reductase converts testosterone to dihydrotestosterone, which mediates development of the external genitalia in the male fetus.
Male neonates with 5alpha-reductase def are born with ambiguous genitalia that typically masculinize at puberty
What is different between the leading and lagging strands?
DNA replication occurs in the 5’-3’ direction on both strands.
In contrast to the continous systhesis of the leading strand, lagging strand synthesis occurs discontinuously and is composed of short stretches of RNA primer plus newly synthesized DNA segments (Okazaki fragments). As a result, lagging strand synthesis requires the repetitive action of DNA primase and DNA ligase
What is bacterial vaginosis?
associated with a grayish-white, malodorous vaginal discharge due to an overgrowth of Gardnerella vaginalis, a facultative anaerobic, gram variable rod.
Clue cells (squamous epithelial cells are covered with bacterial organisms) are seen on wet mount.
What is ichthyosis vulgaris?
caused by filaggrin gene mutations that result in defective keratinocyte desquamation.
It is characterized by dry, scaly skin; manifestations are diffuse but are typically worse on the trunk and the extensor surfaces of the extremities.
Spontaneous deep intracerebral hemorrhage is typically caused by?
hypertensive vasculopathy involving the small, penetrating branches of the major cerebral arteries.
The most frequently affected locations include the basal ganglial (putamen), cerebellar nuclei, thalamus, and pons.
The putamen is supplied by the lenticulostriate arteries, which are deep, small vessel branches off the middle cerebral arteries.
Why does risperidone and other antipsychotics cause hyperprolactinemia?
by blocking D2 receptors on lactotrophs.
Elevated prolactin leads to amenorrhea (inhibition of gonadotropin-releasing hormone release), galactorrhea, and breast soreness.
The secretion of prolactin is controlled by the inhibitory effect of hypothalamic dopamine.
What is the primary treatment for diphtheria?
diphteria antitoxin (passive immunization), which inactivates circulating toxin. Antibiotics should also be administered to reduce continued production of toxin.
What are the normal age-related changes to sleep?
Age-related sleep changes may be reported as insomnia and must be differentiated from primary sleep disorders and other disorders.
Normal changes include decreased total sleep time, increased nighttime awakenings, sleepiness earlier in the evening with earlier morning awakening, and increased daytime napping.
What is seen in folate acid deficiency anemia?
commonly occurs in alcoholism.
It is a megaloblastic anemia that can develop within weeks.
Peripheral bood smear shows macrocytosis, ovalocytosis, and neutrophils with hypersegmented nuclei.
Function of acetyl-coA?
Acetyl-coA stimulates gluconeogenesis by increasing the activity of pyruvate carboxylase when acetyl-coA is abundant. This regulatory step allows pyruvate to be shunted toward acetyl-CoA production when acetyl-CoA levels are low, preventing the cell from becoming depleted of energy.
What is schizoaffective disorder?
For diagnosis of schizoaffective disorder, psychosis must occur in the absence of major mood episodes, but mood episodes must be present for a majority of this lifelong illness.
In bipolar disorder and major depression with psychotic features, psychotic symptoms occur exclusively during mood episodes
What is multiple sclerosis?
an immune-mediated disorder of the central nervous system characterized by focal demyelination (plaques).
Histologically, plaques contain foci of perivenular inflammatory infiltrates made up primarily of autoreactive T lymphocytes and macrophages.
Patchy demyelination occurs followed by astrocyte hyperplasia (glial scarring)
How is isoniazid metabolized?
INH is metabolized by acetylation. The speed with which a patient is able to acetylate drugs depends on whether they are genetically “fast” or “slow” aceylators.
The presence of fast and slow acetylators within the same population results in a bimodal distribution of the speed of isoniazid metabolism.
Slow acetylators are at increased risk of adverse side effects.
What is the number needed to harm?
represents the number of people who must be treated before 1 additional adverse even occurs.
In order to calculate NNH, the absolute risk increase between the treatment and control groups must be known: NNH = 1 / absolute risk increase
What is seen in common fibular (peroneal) nerve injury?
can occur with extrinsic compression at the fibular head, resulting in weakness on foot dorsiflexion and eversion.
Sensation will also be impaired over the lateral shin, dorsal foot, and between the first and second toes.
What can occur with prolonged or high dose treatment of erythropoietin?
Patients with chronic kidney disease often develop normocytic anemia due to erythropoietin (EPO) deficiency.
Treatment with recombinant EPO can dramatically improve tissue oxygen delivery and reduce mortality.
However, prolonged or high-dose treatment can have serious side effects, most notably increased risk of hypertension and thromboembolism.
What is minimal change disease?
caused by immune dysregulation and overproduction of a glomerular permeability factor, which damages podocytes and decreases the anionic properties of the glomerular basement membrane.
This results in selective loss of albumin in the urine, in contrast to the nonselective proteinuria seen in other forms of nephrotic syndrome
Under normal circumstances, pulmonary capillary wedge pressure closely reflects what?
left atrial and left ventricular end-diastolic pressure.
Mitral stenosis leads to an increase in the LA pressure that is reflected as elevated PCWP during pulmonary artery catheterization.
Left ventricular filling may be normal, resulting in an increased pressure gradient between the LA and LV during diastole.
What is the most common finding with posterior cerebral artery stroke?
contralateral homonymous hemianopia. The macula is often spared because there is collateral circulation from the middle cerebral artery to the occipital pole, the area that processes central vision.
What is hematogenous osteomyelitis?
predominantly a disease of children that most frequently affects the long bones.
Staph aureus is implicated in most cases secondary to a bacteremic event.
Strep pyogenes (group A strep) is the second most common cause of hematogenous osteomyelitis.
What is small intestinal bacterial overgrowth?
characterized by bacterial proliferation in the small bowel, leading to mucosal inflammation with subsequent fermentation of carbohydrates and fat malabsorption; it manifests with diarrhea, abdominal distention, and flatulence.
Patients with impaired intestinal peristalsis (eg, systemic sclerosis) are at increased risk.
Treatment: oral antibiotics
Inhalant intoxication is characterized by?
immediate onset of euphoria, lethargy, ataxia and/or loss of consciousness followed by rapid recovery within 45 minutes.
Perioral and perinasal dermatitis (ie, glue sniffer’s rash) may be seen in chronic users.
What is thrombotic thrombocytopenia purpura?
results from impaired function of the von Willebrand factor cleaving protease ADAMTS-13, which causes the accumulation of uncleared vWF multimers that are significantly more prothrombotic.
Patients develop diffuse microvascular thrombosis, which leads to thrombocytopenia and microangiopathic hemolytic anemia
What is renal artery stenosis?
Renal artery stenosis (eg, severe hypertension, abdominal bruits) causes decreased renal artery perfusion, which activates the renin-angiotensin-aldosterone system. Increased secretion of renin leads to increased production of angiotensin I and angiotension II, which causes increased peripheral resistance and elevated systemic blood pressure.
Increased aldosterone secretion causes increased renal Na reabsorption and K and H excretion, resulting in relative hypokalemia and metabolic alkalosis
What is idiopathic precocious puberty?
early onset, pulsatile GnRH secretion, resulting in increased estrogen production.
Estrogens promote bone growth but also epiphyseal plate (ie, growth plate) closure, so without treatment, patients typically have an early growth spurt but a shorter than expected adult height
what is intestinal malrotation?
occurs when the midgut undergoes incomplete physiologic rotation in utero.
A life threatening complication of malrotation is midgut volvulus, in which the small intestines twist around the superior mesenteric artery due to the abnormally mobile mesenteric base.
Patients have bilious emesis, and an upper gastrointestinal series typically shows proximal small intestinal loops on the right side of the abdomen
Chronic volume overload causes what changes in the heart?
Dilation of the left ventricular cavity commonly occurs in response to systolic dysfunction (eg, ischemic heart disease, dilated cardiomyopathy) or certain types of valvular disease (ie, aortic regurg, mitral regurg).
Chronic volume overload causes progressive eccentric hypertrophy that eventually leads to reduced ventricular contractility and decompensated heart failure
MOA of class III antiarrhytmic drugs (amiodarone, sotalol, dofetilide)
predominantly block potassium channels and inhibit the outward potassium currents during phase 3 of the cardiac action potential, thereby prolonging repolarization and total action potential duration
What is allergic rhinitis?
often causes nasal congestion, sneezing, rhinorrhea, and conjunctivitis due to an IgE mediated hypersensitivity response. Patients can often distinguish patterns that suggest reactions to specific allergens
Main side effect of ethambutol
optic neuropathy that results in color blindness, central scotoma, and decreased visual acuity. This adverse side effect may be reversed with discontinuation of the drug
What is intermittent claudication?
muscle pain that is reproducibly caused by exercise and relieved by rest; it occurs due to atherosclerotic stenosis (lipid filled intimal plaques) in the large arteries that prevent sufficient blood flow to exercising muscle.
The lower extremities are most commonly affected; however, proximal lesions (ie, aortioilac occlusion) can cause gluteal claudication and/or impotence.
What is the pathogenesis of retinopathy of prematurity?
involves an initial downregulation of proangiogenic factors (eg, VEGF) due to hyperoxia following delivery.
Subsequently, increased metabolic demand causes relative retinal hypoxia, which stimulates a pathological increase in VEGF leading to aberrant vessel formation.
Neonatal oxygen supplementation increases the risk in premature infants.
What is Yersinia pestis?
the cause of bubonic plague, is transmitted primarily by rodent fleas.
Manifestations include rapid-onset systemic symptoms (eg, high fever, chills, weakness, headache) and painful, purulent regional lymphadenitis.
First line treatment: aminoglycosides, which block bacterial protein synthesis by binding to the 30S ribosomal subunit
What is pyruvate dehydrogenase complex deficiency?
an inhertied inborn error of metabolism causing lactic acidosis and neurologic defects.
Patients are unable to convert pyruvate to acetyl-CoA, resulting in a shunting of pyruvate to lactic acid.
In these patients, metabolism of exclusively ketogenic amino acids (eg, lysine, leucine) can provide energy in the form of acetyl-CoA without increasing lactate production
What is a patent urachus?
The urachus is a remnant of the allantois that extends from the bladder to the umbilicus.
Failed obliteration of the allantois lumen can result in a patent urachus, which presents with urinary drainage from the umbilicus in the neonate.
Side effects of digoxin toxicity
Digoxin toxicity presents with nonspecific gastrointestinal (eg, anorexia, nausea, vomiting) and neurological (eg, fatigue, confusion, weakness) symptoms.
Changes in color vision are a more specific, but rarer, finding. Life-threatening ventricular arrhythmias are the most serious complication
What is odds ratio?
OR = odds of exposure in cases / odds of exposure in controls
OR = ad/bc
What is Lesch-Nyhan syndrome?
Lesch Nysan syndrome (dystonia, self mutilation, hyperuricemia) is caused by a mutation in the gene encoding hypoxanthine-guanine phosphoribosyltransferase (HGPRT).
Reduced HGPRT activity leads to impaired purine salvage and increased de novo purine synthesis, a process necessitating increased phosphoribosyl pyrophosphate amidotransferase activity
Any treatment that prolongs survival but does not cure the disease will do what to the incidence and prevalence?
Incident cases represent new cases diagnosed in a given period of time. Prevalent cases are the total number of cases (both old and new) at a particular point in time.
Any treatment that prolongs survival but does not cure the disease will increase prevalence due to an increase in the number of afflicted (but still living) individuals over time.
What are the predominant cell in the necrotic area of the brain?
microglia are the predominant cell in the necrotic area 3-7 days after the onset of ischemia and phagocytize the fragments of neurons, myelin, and necrotic debris.
Late or inadequate treatment of congenital hypothyroidism results in?
Congenital hypothyroidism is treated with prompt initiation of levothryoxine in early infancy.
Late or inadequate treatment is associated with cognitive (ie, lower intelligence quotient) and neurologic (eg, hearing loss, incoordination) dysfunction.
What is Histoplasma capsulatum?
a dimorphic fungus that exists as a small, ovoid yeast at tissue temperatures.
It replicates within macrophages and spreads through the lymphatic and reticuloendothelial system.
Immunocompetent patients usually have an asymptomatic pulmonary infection, but those who are immunocompromised (eg, advanced AIDS) can develop disseminated disease to the liver, spleen and bone marrow
Sudden upward stretching on the arm at the shoulder can damage what?
The inferior trunk of the brachial plexus carries nerve fibers from the C8 and T1 spinal levels that are responsible for innervating all the intrinsic muscles of the hand (via the median and ulnar nerves).
Sudden upward stretching on the arm at the shoulder can damage the inferior trunk resulting in hand clumsiness and total claw hand deformity.
What is a target cell?
Target cells form when erythrocytes have reduced cell volume (eg, thalassemia, iron def) or excessive membrane (eg, obstructive liver disease, postsplenectomy).
Patients who undergo splenectomy usually develop target cells because the spleen is the primary organ that prunes excessive red cell membrane
Which receptor inhibits insulin secretion?
Alpha-2 adrenergic receptors inhibit insulin secretion, and beta 2 adrenergic receptors stimulate insulin secretion.
The alpha-2 mediated inhibitory effect is generally predominant, causing sympathetic stimulation to lead to overall inhibition of insulin secretion.
What is carcinoid syndrome?
presents with episodic flushing, secretory diarrhea, and wheezing. It can lead to pathognomonic plaque-like deposits of fibrous tissue on the right-sided endocardium, causing tricuspid regurgitation and right sided heart failure.
Elevated 24 hour urinary 5-hydroxyindoleacetic acid can confirm the diagnosis
Vitamin B6 is required at which step in the porphyrin synthesis?
Vitamin B6 (pyridoxine) is a required cofactor for the enzyme 5-aminolevulinate synthase, which catalyzes the first, rate limiting step in porphurin synthesis. Defects in this enzyme causes X-linked sideroblastic anemia.
Aminolevulinic acid synthetase converts succinyl CoA to aminolevulinic acid using b6 as a cofactor.
Most common cause of type 1 diabetes
autoimmune insulitis with progressive beta cell loss
Main cause of type 2 diabetes
Insulin resistance accompanied by relative insulin deficiency
