Uworld27 Flashcards
Function of parietal cells
Parietal cells release hydrogen ions into the gastric lumen by means of the H/K ATPase, which requires hydrolysis of ATP and is therefore an active transport mechanism.
Omeprazole and other proton pump inhibitors suppress the activity of the gastric parietal cell H/K ATPase leading to an increase in the pH of the gastric lumen.
To access the left side of the heart, cardiac venous catheters must cross?
the interatrial septum at the site of the foramen ovale.
Entry into the left atrium allows for direct measurement of left atrial pressure and for access to arrhythmogenic foci on the left atrial myocardium or pulmonary veins.
Neisseria can be isolated on which medium?
Neisseria can be isolated by culture on selective media such as the Thayer-Martin VCN (vancomycin/colistin/nystatin) medium, which inhibits growth of contaminants such as gram+ organisms, gram negative organisms other than Neisseria, and fungi.
What is septic shock?
Septic shock is a dysfunctional host response to an infectious pathogen resulting from massive upregulation of vasodilators.
A vasopressin deficit contributes to unbalanced vasodilation and refractory hypotension.
Hepatic A virus infection is characterized by?
Hepatitis A virus infection is most commonly silent or subclinical (“anicteric”) in young children but can also present as an acute, self limited illness characterized by jaundice, malaise, fatigue, anorexia, nausea, vomiting, RUQ pain, or an aversion to smoking.
What is a migraine?
an episodic neurologic disorder that results in severe, unilateral, throbbing headaches that are often associated with photophobia, phonophobia, and nausea/vomiting.
Migraine attacks typically last 4-72 hours, and up to 25% of patients also develop an aura (focal, reversible neurologic symptoms that precede or accompany the headache)
What is infantile hemangiomas?
benign vascular tumors composed of proliferating endothelial cells that most frequently affect the head or neck region.
Natural history of these lesions involve rapid growth of a red, cutaneous plaque followed by spontaneous regression.
What is schizophrenia?
diagnosed in patients with signs of disturbance for >6 months, including at least 1 month of >2 of the following active symptoms (with at least 1 from the first 3): delusions, hallucinations, disorganized speech, disorganized/catatonic behavior, and negative symptoms.
Treatment of acromegaly
Acromegaly is usually treated with resection of the somatotroph pituitary adenoma, but additional medical therapy is needed for patients with residual tumor.
Octreotide is a long acting somatostatin analogue that inhibits growth hormone secretion and subsequently insulin-like growth factor-1 release. It also reduces residual adenoma size in many patients.
What is the most common etiology of mesial temporal lobe epilepsy?
Recurrent focal impaired awareness seizures that are preceded by a distinctive aura (eg, uneasy epigastric sensation, olfactory hallucinations) are characteristic of mesial temporal lobe epilepsy.
The most common etiology is hippocampal sclerosis (mesial temporal sclerosis), which is associated with childhood febrile seizures.
Formula for absolute risk reduction
Absolute risk reduction = event rate in the control group - event rate in the treatment group
MOA of aromatase inhibitors (anastrozole, letrozole, exemestane)
Estrogen is the main hormone responsible for the growth and development of estrogen receptor-positive breast tumors.
Aromatase inhibitors decrease the synthesis of estrogen from androgens, suppressing estrogen levels and slowing progression of ER+ tumors.
t-test is used to compare?
the difference between the means of 2 groups.
Analysis of variance (ANOVA) compares?
the difference between the means of 2 or more groups.
What is McCune-Albright syndrome?
characterized by the triad of fibrous dysplasia of the bone, endocrine abnormalities, and cafe-au-lait spots.
The condition results from an activating mutation in the G protein/cAMP/adenylate cyclase signaling pathway.
What is acute respiratory distress syndrome?
characterized by hypoxia and bilateral pulmonary infiltrates and is associated with pneumonia, sepsis, trauma, and pancreatitis.
The associated pulmonary edema is noncardiogenic in nature, so the pulmonary capillary wedge pressure will be within the normal range (6-12 mmHg)
What is the mutations seen in adenocarcinoma of the lung?
the most common primary lung cancer in the general population, women, and nonsmokers.
Epidermal growth factor receptor (EGFR) mutations and ALK gene rearrangments are seen more commonly in nonsmokers and thought to contribute to disease formation in this subgroup.
Adenocarcinoma is typically located peripherally and may be associated with clubbing or hypertrophic osteoathropathy.
What is occupational asthma?
involves airway inflammation and bronchoconstriction triggered by sensitization to a workplace aeroallergen (eg, isocyanates, grain proteins).
Improvement on sustained absence from work (eg, vacation) is an important clinical clue.
Normal spirometry does not exclude asthma because bronchospasm may occur intermittently.
What is linkage disequilibrium?
Two allele loci are said to be in linkage disequilibrium when a pair of alleles are inherited together in the same gamete (haplotype) more often or less often than would be expected given random pairing.
This most often occurs when the genes are in close physical proximity on the same chromosome.
What is acute interstitial nephritis?
a common cause of renal dysfunction; up to 75% of cases are due to medications including nonsteroidal anti-inflammatory drugs, antibiotics, diuretics, and proton pump inhibitors.
Presenting features include fever, rash, and eosinophilia.
UA: pyuria and WBC casts with elevated urine eosinophils.
What is sarcoidosis?
an inflammatory disorder characterized histologically by noncaseating granulomas consisting of aggregates of epithelioid macrophages and multinucleated giant cells.
Common manifestations include hilar adenopathy, pulmonary infiltrates, skin rash, ophthalmic findings, and constitutional symptoms.
What is recall bias?
results from study participants’ inaccurate recall of past exposure and occurs most often in retrospective studies such as case-control studies.
People who have experienced an adverse effect are more likely to recall risk factors than those who have not experienced an adverse event.
Hyperprolactinemia suppresses secretion of?
GnRH, which leads to reduced estrogen in women. Low estrogen levels are a risk factor for accelerated bone loss.
What is pseudocholinesterase deficiency?
Succinylcholine, a depolarizing neuromuscular blocking agent, is rapidly hydrolyzed by plasma pseudocholinesterase.
Patients with pseudocholinesterase deficiency have prolonged neuromuscular paralysis after drug adminstration.
What is HIV-associated dementia?
HIV-associated dementia should be suspected in patients with AIDS who have progressive cognitive decline.
The characteristic histopathologic finding is microglial nodules (groups of activated microglia/macrophages around small areas of necrosis) and multinucleated giant cells.
What is injured in a supracondylar humeral fracture?
Supracondylar humeral fractures commonly occur after hyperextension of the elbow as a result of a fall onto an outstretched arm.
The median nerve and brachial artery run along the anteromedial aspect of the elbow and are the structures most likely to be injured with anteromedial displacement of the proximal fracture fragment.
Carotid sinus massage leads to?
an increase in parasympathetic tone causing temporary inhibition of sinoatrial node activity, slowing of conduction through the atrioventricular node, and prolongation of the AV node refractory period.
It is a useful vagal maneuver for termination of paroxysmal supraventricular tachycardia.
What causes head lice?
Pediculus human capitis (ie, head lice) infestation is common in school children and adults who come into close contact with infested individuals.
Transmission is usually by direct contact.
The eggs (nits) are attached to the hair shaft and can be identified on inspection.
First line treatment includes topical pediculicides (eg, permethrin, ivermectin)
MOA of bile acid-binding resins (eg, cholestyramine, colestipol, colesevelam)
inhibit the enterohepatic circulation of bile acids. This leads to diversion of hepatic cholesterol to synthesis of new bile acids, increased uptake of cholesterol from the circulation, and reduced blood LDL levels.
However, bile acid binding resins increase hepatic production of triglycerides and can cause hypertriglyceridemia.
What is mitral stenosis?
opening snap followed by a rumbling diastolic murmur that is best heard over the cardiac apex.
On the left ventricular pressure-volume loop, the opening snap occurs during mitral valve opening at the end of isovolumetric relaxation, and it is followed by a diastolic rumble during diastolic filling.
What is selection bias?
In prospective studies, disproportionate loss to follow up between the exposed and unexposed groups creates the potential for attrition bias, which is a form of selection bias.
As a result, investigators generally try to achieve high patient follow-up rates in prospective studies.
What is the Golgi tendon system?
The muscle spindle system is a feedback system that monitors and maintains muscle length, while the Golgi tendon system is a feedback system that monitors and maintains muscle force.
Golgi tendon organs are exquisitely sensitive to increases in muscle tension but are relatively insensitive to passive stretch.
The internal larygneal nerve mediates?
the afferent limb of the cough reflex above the vocal cords.
Foreign bodies (eg, fish bones) can become lodged in the piriform recess and may cause damage to the nerve, impairing the cough reflex.
In chronic kidney disease, reduced excretion of phosphate can cause hyperphosphatemia. This induces?
hypocalcemia directly by binding free calcium and depositing in tissues, and indirectly by triggering fibroblast growth factor 23 secretion (decreases calcitriol production and intestinal calcium absorption).
The resulting hypocalcemia can manifest as neuromuscular excitability (eg, carpal spasm)
MOA of topical capsaicin
causes defunctionalization of afferent pain fibers and depletion of substance P.
Initial application results in a burning stinging sensation, but chronic exposure leads to reduced pain transmission.
What is Pott disease?
Mycobacterium tuberculosis spondylitis (Pott disease) is usually the result of hematogenous seeding of vertebrae from primary pulmonary infection.
Manifestations typically arise months or years later (due to reactivation) and include chronic, progressive back pain, fever, and radiographic evidence of vertebral bone destruction and fluid collection.
What are the most common adverse effects of psychostimulant meds used to treat attention-deficit hyperactivity disorder?
decreased appetite and insomnia. They are usually mild and can be managed without stopping the medication.
What is hirschsprung disease?
a congenital disorder caused by failure of normal craniocaudal migration of neural crest cells during embryogenesis.
The affected colon segment (eg, rectosigmoid) lacks ganglionic innervation and is unable to relax, resulting in obstruction with failure to pass meconium and bilious emesis.
Forceful expulsion of gas and stool on rectal exam is typical.
Acetylcholine release from presynaptic terminal vesicles at the neuromuscular junction depends upon?
the influx of extracellular calcium into the presynaptic terminal.
Calcium influx into the nerve terminal occurs following neuronal depolarization and opening of voltage gated calcium channels.
What is septic abortion?
Symptoms of septic abortion typically include fever, abdominal pain, uterine tenderness, and/or malodorous discharge after pregnancy termination.
Common pathogens include Enterobacteriaceae, group A strep, and Staph aureus.
Treatment: urgent surgical evacuation and broad spectrum antibiotics.
What is C1 inhibitor (C1INH) deficiency?
C1INH deficiency causes increased cleavage of C2 and C4 and results in inappropriate activation of the complement cascade.
C1INH also blocks kallikrein-induced conversion of kininogen to bradykinin, a potent vasodilator associated with angioedema.
MOA of ACE inhibitors?
ACE inhibitors reduce angiotensin II levels and cause efferent arteriole dilation, thereby decreasing the glomerular filtration pressure and filtration rate.
This can precipitate acute renal failure in patients with reduced intrarenal perfusion pressure at baseline (eg, renal artery stenosis, congestive heart failure, hypovolemia)
Pathogenesis of Mycobacterium tuberculosis infection
Th1 cells release interferon-gamma, leading to the activation of macrophages, a process critical for control of Mycobacterium tuberculosis infection.
Activated macrophages form mature phagolysosomes that destroy phagocytosed mycobacteria and can differentiate into epithelioid and Langhans giant cells to wall off extracellular mycobacteria within caseating granulomas.
Function of vitamin C
cofactor for the hydroxylation of proline and lysine during collagen synthesis, which is essential for maximum tensile strength.
Def (scurvy) is charactered by periodontal disease, impaired wound healing, vascular wall fragility (eg, perifollicular, subperiosteal hemorrhage), follicular hyperkeratosis, and corkscrew hairs.
Function of hydroxyurea
Hydroxyurea increases fetal hemoglobin production, which reduces erythrocyte sickling in patients with sickle cell disease.
It also inhibits ribonucleoside reductase, which decreases deoxynucleoside triphosphates available for DNA synthesis; this leads to macrocytosis and with high doses, pancytopenia
Following endothelial damage, von Willebrand factor binds to?
glycoprotein Ib receptors on platelets to mediate platelet adherence.
The ristocetin cofactor assay measures platelet agglutination via binding of glycoprotein Ib receptors to vWF; it will be abnormal in vWF def but will correct with the addition of normal (vWF-containing) plasma.
Def of vitamin B12
B12 is an essential cofactor in the recycling of 5-methyl-tetrahydrofolate, which is required for amino acid, purine, and thymidine synthesis.
Def primarily affects hematopoiesis and is marked by impaired nuclear maturation, leading to macrocytic red blood cells and hypersegmented neutrophils; increased apoptosis often also leads to anemia and mild thrombocytopenia/leukopenia.
Activating mutations of the KRAS gene lead to constitutive activation of?
epidermal growth factor receptor (EGFR) pathway, promoting increased cell proliferation and growth.
Tumors harboring these mutations are resistant to treatment with anti-EGFR drugs (eg cetuximab, panitumumab)
What is aortic stenosis most commonly results from?
from age-related calcific aortic valve disease.
The early pathogenesis closely mimics that of arterial atherosclerosis. In the later stages, fibroblasts differentiate into osteoblast-like cells and deposit bone matrix, leading to progressive valvular calcification and stenosis.
What are the difference between long acting insulin analogues (eg, glargine) and rapid acting insulins (eg, aspart, lispro)?
Long-acting insulin analogues (eg, glargine) have an extended duration of action without a noticeable peak in activity and are typically given once daily to mimic basal insulin secretion.
Rapid-acting insulins (eg, aspart, lispro) are quickly absorbed from the injection site and are given at mealtimes to replicate postprandial insulin secretion.
What are hepatocellular adenomas?
benign liver tumors found predominantly in young women with a history of oral contraceptive use.
They are usually solitary, unencapsulated masses composed of benign hepatocytes and prominent arteries without normal portal tracts.
Patients may be asymptomatic, have abdominal pain, or have intrabdominal bleeding due to tumor rupture.
Bartonella henselae causes?
cat scratch disease, bacillary angiomatosis, and culture negative endocarditis.
Cat scratch disease: low fever, lymphadenopathy, and a self limited course.
What is the blood supply of the esophagus?
Forceful retching can lead to superficial mucosal lacerations (eg, Mallory-Weiss tears) of the distal esphagus, an area that receives most of its arterial blood supply from branches of the left gastric artery.
proximal esophagus: inferior thyroid artery
mid esophagus: branches of the thoracic aorta.
What type of tumor is a teratoma?
Teratomas contain differentiated tissues from each of the 3 primary germ cell layers and are a type of germ cell tumor.
Germ cell tumors originate from primordial germ cells and most commonly arise within the gonad itself (eg, ovarian germ cell tumor)
What drug properties help the liver eliminate drugs?
While the kidney is the primary site of elimination of most drugs, the liver is the main site of biotransformation of these agents in preparation for elimination.
Drugs that are more lipophilic (high Vd, good penetration into CNS) are preferentially processed by the liver into more polar compounds for easier elimination in the bile and urine.
Liver disease (eg, cirrhosis) or the concomitant use of other drugs may limit or enhance the clearance of drugs metabolized in the liver.
What is methylmalonic acidemia?
an organic acidemia/aciduria in newborns caused by deficiency of methylmalonyl-CoA mutase.
Labs: elevated propionic acid, hypoglycemia, metabolic acidosis (ketone-mediated), and hyperammonemia.
What test should be used for screening for life-threatening diseases?
The sensitivity of a test refers to its ability to correctly identify those with the disease.
A highly sensitive test should always be considered over a high specific test when screening for life threatening diseases, where identification of every person with the disease is important.
Melanoma has what kind of mutation?
BRAF is a protein kinase involved in activation of signaling pathways for melanocyte proliferation; the BRAF V600E mutation is seen in 40-60% of patients with melanoma.
What are the physiologic responses to maintain adequate O2 delivery to the tissues in the hypoxic environment of high altitude?
hypoxic pulmonary vasoconstriction (increased pulmonary vascular resistance), increased sympathetic activity to increase cardiac output, and aldosterone suppression to reduce plasma volume.
What is eosinophilic meningitis?
most often due to helminth infection (eg, Angiostrongylus).
Peripheral eosinophilia is largely mediated by the release of IL-5 in response to helminths, allergens, drugs or rheumatic disease.
Occlusion of the middle cerebral artery results in?
contralateral hemiparesis and hemisensory loss of the face and upper limb with relative preservation of lower limb function.
If the occluded MCA is in the dominant (usually left) hemisphere, aphasia may also occur.
function of b-hCG
b-hCG is a hormone secreted by the placental syncytiotrophoblast after uterine invasion that signals the ovary to maintain the corpus luteum, which produces progesterone in early pregnancy.
MOA of vaptans (eg, tolvaptan)
Vaptans (eg, tolvaptan) are vasopressin V2 receptor antagonists (ie, aquaretics) used to treat hyponatremia.
Vaptans block the effects of antidiuretic hormone (vasopressin), increasing renal free water excretion without directly affecting excretion of sodium or potassium.
Diuresis of free water with vaptans results in increased plasma osmolality, increased serum sodium, increased urine output, and lowered urine osmolality.
Paraneoplastic syndromes can occur due to?
the production of hormone like substances from tumor cells.
They can also result from immune reactions against tumor cells that cross-react with normal cells, causing dysfunction and/or damage to healthy organs and tissues.
Neurologic paraneoplastic syndromes (eg, paraneoplastic cerebellar degeneration) are an autoimmune phenomenon.
Function of B6 pyroxidine
Transamination reactions typically occur between an amino acid and an a-keto acid.
The amino group from the amino acid is transferred to the a-keto acid, and the a-keto acid in turn becomes an amino acid.
Pyridoxal phosphate (active vitamin B6) serves as a cofactor in amino acid transamination and decarboxylation reactions.
What is a prolactinoma?
Prolactinomas are the most common pituitary adenoma and can cause galactorrhea, menstrual irregularities, and infertility in premenopausal women.
Large pituitary adenomas can cause headaches from mass effect and bitemporal hemianopsia from compression of the optic chiasm.
What are the cardiac changes in pregnancy?
During pregnancy, systemic vascular resistance decreases and plasma blood volume increases.
Venous capacitance and a decrease in pulmonary vascular resistance allow for accomodation of increased blood volume without affecting central venous pressure.
Despite a normal central venous pressure, peripheral edema is common in pregnancy due to decreased capillary oncotic pressure that encourages leakage of fluid into dependent peripheral tissues (eg, lower extremities)
Meningiomas arise from?
the meningothelial cells of the arachoid.
Therefore, when they form in the spinal cord, they are located within the meninges in the intradural extramedullary space.
What does HBeAg signify?
Infants born to HBeAg+ mothers have a high risk for acquiring perinatal hep B virus infection.
Infected neonates have high levels of HBV replication and are at high risk for chronic infection, but are usually asymptomatic or have only mildly elevated liver function tests.
What is basal cell carcinoma?
presents as a pearly, skin colored papule/nodule on the face.
Biopsy classically shows nests of basaloid keratinocytes with peripheral palisading and clefting artifact.
Unresected BCCs rarely metastasize but may undergo continued local growth, causing progressive surrounding tissue destruction.
When to used a broad spectrum anticonvulsants versus narrow spectrum?
Broad spectrum anticonvulsants (eg, levetiracetam, valproic acid) treat both focal and generalized onset seizures, whereas narrow spectrum anticonvulsants (eg, carbamazepine, phenytoin) are primarily used only for focal onset seizures.
Because the seizure in juvenile myoclonic epilepsy are usually generalized onset (ie, affect both cerebral hemispheres at onset), treatment is with a broad-spectrum agent such as valproic acid.
Prolonged systemic hypertension leads to concentric left ventricular hypertrophy via?
the addition of myocardial contractile fibers in parallel.
The thickening of the LV walls reduces LV compliance, leading to impaired diastolic filling and heart failure with preserved ejection fraction.
In response to reduced cardiac output, the kidneys activate the renin-angiotensin-aldosterone system, stimulating sodium retention and vasoconstriction that worsens volume overload and can lead to decompensated heart failure.
Streptoccous gallolyticus (S bovis) endocarditis and bacteremia are associated with?
gastrointestinal lesions (colon cancer) in 25% of cases. When S gallolyticus is cultured in blood, workup of colonic malignancy with colonoscopy is essential.
Where does the ureter lie within the true pelvis?
The ureters pass posterior to the ovarian (gonadal) vessels within the retriperitoneum and cross anterior to the common/external iliac arteries to reach the true pelvis.
Within the true pelvis, the ureters lie anterior to the internal iliac artery and posterior to the uterine artery.
What is a left ventricular free wall rupture?
a mechanical complication that can occur within 5 days or up to 2 weeks following transmural (ST-elevation) myocardial infarction.
Patients usually develop acute cardiac tamponade with hypotension and obstructive shock that rapidly leads to cardiac arrest.
Short non-coding RNA sequences (eg, microRNA and small interfering RNA) induce?
posttranscriptional gene silencing by base pairing with complementary sequences within target mRNA molecules.
Blastomyces dermatitides can cause?
pulmonary disease in the immunocompetent host.
Dissemination (most commonly to skin and bones) occurs in immunocompromised individuals.
What are crescents made of?
Cresent formation on light microscopy is diagnostic for rapidly progressive glomerulonephritis.
Crescents consist of glomerular parietal cells, lymphocytes, and macrophages along with abundant fibrin deposition.
Crescents eventually become fibrotic, disrupting glomerular function and causing irreversible renal injury.
What is exogenous hyperthyroidism is characterized by?
elevated free thyroxine (T4), suppressed TSH, and low/undetectable thyroglobulin.
It can occur with surreptitious levothyroxine misuse, animal-sourced thyroid supplements, and erroneous dosing of thyroid replacement therapy.
Over time, the lack of TSH stimulation causes the thyroid follicles to become atrophic.
Antibiotics exhibiting concentration-dependent killing can be administered using relatively high doses given at lower frequency. This allows for?
Effective microbial killing while preventing adverse effects that may occur with prolonged systemic exposure.
What is von hippel lindau disease?
A cerebellar hemanioblastoma is associated with congenital cysts of the kidneys, liver, and/or pancreas is highly suggestive of von-hippel Lindau disease, a rare autosomal dominant condition.
What is Hyper-IgE syndrome?
elevated IgE levels and is caused by impaired neutrophil activation and migration due to a defect in T-helper cell type 17 cells.
Typical findings include noninflammatory (ie, cold) abscesses, recurrent sinopulmonary infections, and chronic atopic dermatitis.
Which malignancies have a propensity for bony metastasis?
Clinical features that suggest a malignant cause of back pain include persistent pain at night, no relief with rest, onset at age >50, and systemic symptoms.
Common malignancies have a propensity for bony metastasis: prostate, breast, kidney, thyroid, and lung.
What is methadone?
a mu-opioid receptor agonist used for maintenance treatment for opioid use disorder; it is metabolized by the cytochrome P-450 system, particularly by CYP3A4.
Certain inhibitors of CYP3A4 (eg, azoles, fluoxamine, ciprofloxacin, clarithromycin, cimetidine) can increase plasma methadone concentration and lead to opioid toxicity (eg, sedation, respiratory depression, miosis)
What is benign paroxysmal positional vertigo?
causes brief (<1 min) episodes of vertifo triggered by changes in head position.
Triggering an episode by using provocative head positioning maneuvers (eg, Dix-Hallpike) is diagnostic.
What is familial adenomatous polyposis?
autosomal dominant hereditary disorder that results in the formation of innumerable colonic polyps and a nearly 100% risk of colorectal cancer.
It arises due to germline mutation in the adenomatous polyposis coli tumor suppressor gene.
What is Wernicke encephalopathy?
a complication of thiamine deficiency and is characterized by oculomotor dysfunction, encephalopathy, and ataxia.
Chronic deficiency results in Korsakoff syndrome (eg, anterograde and retrograde amnesia, confabulation, apathy).
Thiamine is involved in glucose metabolism, and areas of the brain with high metabolic demands are particularly susceptible; the mammillary bodies are most commonly affected.
What is the cause of Meckel diverticulum?
The vitelline (omphalomesenteric) duct normally obliterates during early embyologic development.
Incomplete obliteration can result in a spectrum of anomalies, including vitelline duct cyst (ie, cyst connected by fibrous bands to the ileum and umbilicus) and Meckel diverticulum.
Genome wide association studies aim to identify associations between?
thousands of genetic variants and a disease.
Because of the increase risk of false positive results when multiple tests are performed simultaneously, a smaller genome-wide p value is typically used.
Pathogenesis of toxic shock syndrome
Toxic shock syndrome is typically associated with the prolonged use of tampons or wound packing, which allows Staph aureus to replicate locally and release pyrogenic toxic superantigens (eg, toxic shock syndrome toxin-1) into the blood.
Superantigens bind to the MHC-II complex of antigen presenting cells without processing and nonspecifically activate T cells.
This leads to a dramatic release of inflammatory cytokines, which causes the manifestations of the disease (eg, hypotension, high fever, organ failure, diffuse, erythematous rash)
What is hyperosmotic volume contraction?
Volume contraction and expansion can be divided into isomotic, hyposmotic, and hyperosomotic states.
Hyperosomotic volume contraction is caused by a loss of free water (with retention of electrolytes). It can occur in patients with diabetes insipidus or as a result of decreased fluid intake/excessive sweating.
What nerves mediated the biceps and brachioradialis reflexes?
C5-C6
What is a gliobastoma?
an aggressive primary brain neoplasm that generally presents with slowly worsening headache, seizure, and/or focal neurologic issues.
Most cases are associated with oncogenic mutations that increase epidermal growth factor receptor expression on tumor cells, leading to increased transduction of growth signals that promote cellular survival and proliferation.
What is bubonic plague?
Bubonic plague causes a febrile illness with regional inflammatory lymphadenopathy (buboes).
The underlying pathogen is Yersinina pestis, a small gram-negative bacillus/coccobacillus that exhibits bipolar staining (resembling a closed safety pin).
The major environmental reservoir is rodents; transmission usually occurs via rodent fleabite.
What is anterior cord syndrome?
Ischemia of the anterior 2/3 of the spinal cord can occur with disruption of the anterior spinal artery blood supply.
The resulting anterior cord syndrome causes bilateral distal loss of pain, temperature, and crude touch sensation (from injury to the spinothalamic tracts) and paralysis (from injury to the lateral corticospinal tracts).
What is phase 1 clinical trials?
A phase 1 trial assesses the pharmacokinetics, pharmacodynamics, and safety profile (eg, adverse events, toxicity) of a new treatment in humans.
It is usually conducted on a small number of healthy subjects.
Transient ischemic attacks resulting in left leg weakness and vision loss in the right eye are likely due to?
emboli originating from the right internal carotid artery.
The brachiocephalic artery branches from the aortic arch, then divides into the righ subclavian and right common carotid arteries.
The left common carotid and left subclavian arteries branch directly from the aortic arch.
What is osteogenesis imperfecta?
results from defective synthesis of type 1 collagen by osteoblasts.
Clinical findings: history of fractures after only minimal trauma, blue sclerae, and small, malformed teeth.
In most patients, osteogenesis imperfecta is transmitted by autosomal dominant inheritance.
MOA of benzodiazepines?
bind GABA-A receptors, resulting in an increased frequency of chloride channel opening in the presence of GABA.
Indications for prescribing include short-term treatment of anxiety disorders and alcohol withdrawal syndrome.
Arteriovenous malformations can result in?
Arteriovenous malformations occur when an artery directly anastomoses with veins without an interposed capillary bed.
They may result in spontaneous intracerebral hemorrhage or seizures, or they may be discovered incidentally when brain imahing is obtained for another reason.
