Uworld 7 3/10/23

thyroid migration

The thyroid gland is formed from evagination of the pharyngeal epithelium and descends to the lower neck. Due to failure of migration, the thyroid can reside anywhere along the thyroglossal duct's usual path, including the tongue (lingual thyroid).

What part of duodenum is involved in SMA syndrome, and what does it get trapped between?

The transverse segment of the duodenum travels through a mesenteric fat pad that provides structural support for the superior mesenteric artery (SMA). Conditions that deplete mesenteric fat (eg, hypermetabolic states, starvation) may allow the SMA to compress the transverse segment against the aorta, causing progressive abdominal distension and recurrent bilious vomiting (ie, superior mesenteric artery syndrome).

Vitelline duct abnormalities

The vitelline (omphalomesenteric) duct normally obliterates during early embryologic 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.

NADPH is important for ?

This molecule is necessary for reducing glutathione (protects red blood cells from oxidative damage) and for the biosynthesis of cholesterol, fatty acids, and steroids. Glucose-6-phosphate dehydrogenase is the rate-limiting enzyme in the pentose phosphate pathway, the major source of cellular NADPH.

high TSH low T4 in a newborn

Thyroid dysgenesis (ie, hypoplasia, aplasia, ectopy) is the most common cause of primary congenital hypothyroidism.

blurred vision, fever, altered mental status, flushed skin, and dry mucous membranes, dilated pupils

anticholinergic toxicity (due to Atropine or scopolamine) competitively inhibit acetylcholine at the muscarinic acetylcholine receptor. The effects can be memorized with the mnemonic, "Blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, full as a flask, and fast as a fiddle," and **can be reversed by cholinesterase inhibitors (physostigmine)**.

Ferruginous bodies

asbestos fiber coated by iron

inheritance of HOCM

autosomal dominant Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder caused by mutation in one of several genes encoding the myocardial contractile proteins of the cardiac sarcomere. Mutations that affect cardiac *myosin binding protein C or cardiac beta-myosin heavy chain* are responsible for the majority of identifiable mutations in patients with HCM.

G protein coupled receptors on pancreatic beta cells

beta 2 - increase insulin release alpha 2 - decrease Epinephrine stimulates both. The alpha-2-mediated inhibitory effect is generally predominant, causing sympathetic stimulation to lead to overall inhibition of insulin secretion.

utricaria

dermal edema Urticaria is a transient hypersensitivity disorder characterized by pruritic erythematous plaques that arise suddenly and resolve over hours. They are most often caused by IgE-mediated degranulation of mast cells, leading to increased permeability of the microvasculature with edema of the superficial dermis.

Coronary heart disease is the most common cause of death in patients with

diabetes

positive anti histone

drug induced lupus

what causes hypoglycemia in infants born to diabetic mothers

excessive fetal insulin production Neonates born to mothers with poorly controlled diabetes during pregnancy are exposed to high maternal glucose levels in utero, resulting in beta cell hyperplasia followed by excessive fetal insulin production. Fetal hyperinsulinemia causes neonatal hypoglycemia, polycythemia, and macrosomia.

excessive bleeding in patients with renal failure

excessive uremia impair platelet aggregation Abnormal bleeding in patients with uremia is due to a qualitative platelet disorder that causes prolonged bleeding time with normal platelet count, prothrombin time, and activated partial thromboplastin time.

Patients who have overdosed on beta blockers should be treated with

glucagon, which increases heart rate and contractility independent of adrenergic receptors. Glucagon activates G-protein-coupled receptors on cardiac myocytes, causing activation of adenylate cyclase and raising intracellular cAMP. The result is calcium release from intracellular stores and increased sinoatrial node firing.

walking barefoot in sand can cause

hookworm infection Hookworm infections are transmitted via direct contact between human skin and contaminated soil/sand (eg, walking barefoot). Dermal penetration is often characterized by an intensely pruritic papule that may form serpiginous tracks due to the subcutaneous migration of hookworm larvae.

comprehending meaning of a sentence tests what region of brain

language comprehension - Wernicke's - dominant superior temporal gyrus

The most common outcome of hepatitis C infection without antiviral treatment is

lifelong persistent infection (ie, chronic hepatitis C). Of those with chronic hepatitis C, approximately 20% develop cirrhosis, and only a minority experiences complications (eg, ascites, variceal bleeding, hepatocellular carcinoma).

what drugs can cause orthostatic hypotension

meds used for BPH - blocks alpha 1 receptors Orthostatic hypotension is a frequent cause of lightheadedness and syncope and is defined as a decrease in systolic (>20 mm Hg) or diastolic (>10 mm Hg) blood pressure on standing from the supine position. Medications (α1-adrenergic antagonists, diuretics), volume depletion, and autonomic dysfunction are common causes of orthostatic hypotension.

in pelvic fracture where is the urethra damaged

membranous segment of the posterior urethra Injury to the posterior urethra is associated with pelvic fractures, and the anterior urethra is most commonly damaged in straddle injuries. Inability to void with a full bladder sensation, a high-riding boggy prostate, and blood at the urethral meatus are suggestive of urethral injury, particularly in the presence of a pelvic fracture. If urethral injury is suspected, placement of a Foley catheter is contraindicated.

what is abnormal in duchene

mutation affecting sarcolemma- cytoskeleton linker protein Duchenne muscular dystrophy is an X-linked recessive myopathy that manifests with proximal muscle weakness and enlargement of the calf muscles in boys age 2-5. It most often results from frameshift deletions affecting the dystrophin gene. Dystrophin provides a stabilizing interaction between the sarcolemma and the intracellular contraction apparatus, and disruption of the protein results in membrane damage and myonecrosis.

Bloody diarrhea, left sided abdominal pain, outbreak, fever

Acute-onset bloody diarrhea is most commonly due to Escherichia coli O157:H7, Shigella, or Campylobacter infection. *Shigella* infection also classically causes high fever and left-sided abdominal tenderness (due to rectosigmoid involvement) and often occurs in outbreaks (eg, day care center).

Adolescent Gynecomastia concerning when?

Adolescent gynecomastia is often physiologic due to an imbalance of estrogens and testosterone in early puberty. Features suggestive of pathologic gynecomastia include onset before or after midpuberty (eg, no secondary sexual characteristics), findings consistent with systemic illness (eg, goiter), as well as size >4 cm, rapid progression, and location eccentric to the nipple areolar complex.

Phosphatidylinositol 2nd messenger system

After a ligand binds to a G protein-coupled receptor that activates phospholipase C, membrane phospholipids are broken down into diacylglycerol (DAG) and inositol triphosphate (IP3). Protein kinase C is subsequently activated by DAG and calcium; the latter is released from the endoplasmic reticulum under the influence of IP3.

receptors and their mechanism of action

Alpha-1 ↑ IP3 Peripheral vasoconstriction Urethral constriction Pupillary dilation Alpha-2 ↓ cAMP CNS sympatholytic ↓ insulin release & intestinal motility Beta-1 ↑ cAMP ↑ Cardiac contractility & heart rate ↑ Renin release by JG cells of kidney Beta-2 ↑ cAMP Peripheral vasodilation Bronchodilation Muscarinic-2 -->Atropine blocks this receptor ↓ cAMP ↓ Cardiac contractility & heart rate Muscarinic-3 ↑ IP3 Bronchoconstriction ↑ insulin release & intestinal motility Bladder contraction Pupillary constriction Peripheral vasodilation*

What antibiotic will be affected if the bug has an enzyme in cytoplasmic surface of the cell membrane and that catalyzes the transfer of acetyl groups to exogenous substances

Aminoglycoside (gentamicin) antibiotic-modifying enzymes add chemical groups to the antibiotic, which diminishes its ability to bind to the 16S ribosomal RNA within the 30s ribosomal subunit.

dopamine pathways

Antipsychotic medications work by blocking dopamine-2 receptors in the mesolimbic dopamine pathway. Dopamine-2 receptor blockade in the tuberoinfundibular pathway can result in galactorrhea and amenorrhea.

thickening inside the chest wall + lower lung fibrosis

Asbestosis is a pneumoconiosis that occurs with inhalation of asbestos fibers, most commonly in patients with occupational exposure (eg, insulation installation, shipbuilding, pipe work). Histopathology demonstrates diffuse interstitial fibrosis and ferruginous asbestos bodies (translucent fibers coated with a golden iron-containing material). Pleural disease (eg, plaques, benign effusions) is common.

reye syndrome

Aspirin in this setting is a mitochondrial toxin that leads to hepatic steatosis, hyperammonemia, and diffuse astrocyte swelling (ie, cerebral edema).

dark brown gallstone composed of calcium bilirubinate. what enzyme is responsible

Brown pigment gallstones are composed of calcium salts of unconjugated bilirubin and arise secondary to bacterial or helminthic infection of the biliary tract. *Beta-glucuronidase* released by injured hepatocytes and bacteria hydrolyzes bilirubin glucuronides to unconjugated bilirubin. The liver fluke Clonorchis sinensis has a high prevalence in East Asian countries and is a common cause of pigment stones.

Which of the following effector cells are primarily responsible for immunologic control of primary TB

CD4 T cells and macrophages Mycobacterium tuberculosis primarily replicates within the phagosome, leading to display of mycobacterial antigens on major histocompatibility complex class II molecules. This results in the activation of CD4 cells and subsequent control of the infection with macrophages. NOT CD8 T cells because - Intracellular organisms that replicate in the cytosol, such as viruses or certain intracellular bacteria (eg, Listeria), are processed by the proteasome and displayed on major histocompatibility complex (MHC) class I molecules. This leads to the activation of CD8 T lymphocytes.

as you age, how is ejection fraction maintained

Cardiomyocyte hypertrophy (ie, concentric left ventricular hypertrophy) occurs with age to allow for maintenance of left ventricular contractility and ejection fraction despite cardiomyocyte dropout and increased left ventricular afterload (due to reduced aortic compliance).

loose stools, abdominal cramps, and microcytic anemia

Celiac disease is an immune-mediated disorder triggered by dietary gluten that causes small-bowel malabsorption. Because the proximal small bowel is primarily affected, iron deficiency leading to microcytic anemia is common. Histopathology is characterized by intraepithelial lymphocytosis, loss of intestinal villi, and mucosal atrophy.

Trypanosoma cruzi

Chagas disease is a protozoal illness that is endemic to Latin America. Patients in rural areas are at greatest risk when their houses harbor the vector (Triatome bug) in adobe walls or thatched roofs. Acute infections are often asymptomatic, but patients can develop Chagas *cardiomyopathy* (eg, heart failure, ventricular arrhythmias, ventricular aneurysms) several decades later.

prolonging QRS with no effect on QT

Class 1C antiarrhythmic agents (flecainide) block the fast sodium channels responsible for ventricular depolarization (phase 0), prolonging QRS duration with little effect on the QT interval. Class 1A and class III agents cause the most QT prolongation.

Dofetilide

Class III antiarrhythmic

This patient is agitated and restless and has dilated pupils, tachycardia, and hypertension

Cocaine intoxication causes increased sympathetic activity, which may be recognized by agitation, dilated pupils, tachycardia, and hypertension. Cocaine-induced chest pain typically results from myocardial oxygen supply-demand mismatch (ie, myocardial ischemia) in the setting of *coronary artery vasoconstriction*. Sublingual nitroglycerin and benzodiazepines help improve the myocardial ischemia and relieve the chest pain.

Neutropenic fever

Complication of Chemotherapy <500 Neutrophils & Fever Patients with neutropenic fever (ie, temperature >38.3 C [>101 F] and absolute neutrophil count <500/mm3) are at risk for overwhelming bacterial infections. The majority of severe infections that cause rapid clinical deterioration (eg, 4 hours) are caused by gram-negative organisms that produce endotoxins.

protein kinase A

Protein kinase A is responsible for the intracellular effects of the G protein-mediated adenylate cyclase second messenger system. Hormone receptors that use this system include the TSH, glucagon, and PTH receptors.

pulmonary infarct in a IV drug user

Pulmonary infarcts are typically hemorrhagic (red) and wedge-shaped in the periphery of the lung. Intravenous drug users are at increased risk of *tricuspid valve endocarditis*, which can cause multiple septic pulmonary infarcts due to embolization of tricuspid valve vegetation fragments.

hyperkeratosis, parakeratosis, dilated capillaries in the dermal papillae, and foci of neutrophils in the superficial epidermis.

psoriasis

Fate of Pyruvate

pyruvate -- lactate dehydrogenase --> lactate pyruvate -- pyruvate carboxylase --> oxaloacetate pyruvate -- pyruvate dehydrogenase --> acetyl co A Impaired intestinal blood flow (eg, acute mesenteric ischemia) creates an anaerobic environment that leads to an elevated NADH/NAD+ ratio. This decreases activity of pyruvate dehydrogenase (converts pyruvate → acetyl-CoA) while stimulating lactate dehydrogenase (converts pyruvate → lactate), shunting the metabolic fate of pyruvate toward lactate production. Patients with significant tissue ischemia are therefore at risk of lactic acidosis.

cardiac tamponade - what happens to right aterial cavity size, left arterial pressure, central venous pressure and stroke volume

right arterial cavity size decrease left arterial pressure increase central venous p increase SV decrease Cardiac tamponade involves increased pericardial pressure that restricts diastolic filling of the right-sided heart chambers, leading to obstructive shock with increased central venous pressure and decreased stroke volume and cardiac output. As tamponade progresses, diastolic pressures in all 4 cardiac chambers increase and equalize with pericardial pressure (and with one another), stagnating blood flow within the heart.

Rodenticide Toxicity

similar to warfarin toxicity give fresh frozen plasma

The most important determinant of intravenous infusion rate is

the radius (diameter) of the intravenous catheter. For patients requiring a rapid blood transfusion, the shortest possible catheter with the widest possible diameter (eg, a large-bore peripheral intravenous catheter) should be selected.

Mefloquine chemoprophylaxis for malaria must be continued for 4 weeks after return from a malaria-endemic region because

to ensure the elimination of hepatic schizonts (which mature in the liver over 8-30 days). Mefloquine is a schizonticide that actively destroys replicating parasites within red blood cells. However, it is inactivated in the liver and has no efficacy against hepatic (exoerythrocytic tissue) schizonts. Because P falciparum schizonts mature in the liver over 8-30 days, travelers must take mefloquine chemoprophylaxis for 4 weeks upon returning from malaria-endemic areas to ensure that schizonts released from the liver are destroyed when they infect red blood cells.

Lepromin skin test

will be positive in patients with tuberculoid leprosy as they exhibit a strong CD4+ TH1 cell-mediated immune response to Mycobacterium leprae. Patients with lepromatous leprosy will test negative due to their weak TH1 cell-mediated immune response.

Drug-induced lupus has been linked to what liver process

Drug-induced lupus erythematosus (DILE) is characterized by abrupt onset of lupus symptoms (eg, fever, arthralgias, pleuritis) with positive anti-histone antibodies. It has been linked to drugs metabolized by *N-acetylation in the liver* (eg, procainamide, hydralazine, isoniazid). Genetically predisposed individuals who are slow acetylators are at greater risk for developing DILE.

Posttransplantation lymphoproliferative disorder occurs in patients who have undergone solid-organ or stem cell transplantation and are taking high-dose immunosuppressive medications. Most cases are caused by the reactivation of

Epstein-Barr virus, which generates viral proteins that stimulate B-cell proliferation and survival. Patients usually have mononucleosis-like symptoms.

Fibroadenoma histology

Fibroadenomas are the most common benign tumor of the breast. They are characterized histologically by a myxoid stroma that encircles and sometimes compresses epithelium-lined glandular and cystic spaces.

Tularemia

Francisella tularensis is a highly virulent, gram-negative coccobacillus transmitted to humans during contact with an infected wild animal (eg, hare, rabbit, squirrel) or due to a bite with a tick or mosquito that recently fed on an infected animal. The most common manifestation is ulceroglandular disease, which is characterized by rapid-onset fever, a single papuloulcerative lesion with central eschar at the site of inoculation, and painful regional lymphadenopathy.

why is a very low p value used in genome wide association studies

Genome-wide association studies aim to identify associations between thousands of genetic variants and a disease. Because of the increased risk of false-positive results when multiple tests are performed simultaneously, a smaller genome-wide p-value is typically used.

why are ovarian cancer cells more response to cisplatin than paclitaxel

Germline mutations in the BRCA gene dramatically increase the risk for breast and ovarian cancer due to an inability to repair double-stranded DNA breaks. Cancers with BRCA gene mutations are often particularly susceptible to treatment with platinum compounds (eg, carboplatin), which cause DNA cross-linking requiring repair by BRCA-encoded machinery.

Patients have recurrent, self-resolving episodes of scleral icterus and jaundice triggered by stress.

Gilbert syndrome is characterized by indirect hyperbilirubinemia due to decreased bilirubin conjugation.

acute hemolysis after ciprofloxacin

Glucose-6-phosphate dehydrogenase deficiency is an X-linked recessive disorder that limits the availability of antioxidants in erythrocytes. Affected patients are susceptible to acute hemolysis following exposure to oxidative insults, particularly acute infection, oxidizing foods, and medications (eg, fluoroquinolones).

Norepinephrine extravasation

Happens occasionally when norepinephrine is being infused... NE causes intense alpha-1 receptor vasoconstriction which can lead to the tissue to become cold, hard, pale.... Eventually necrosis. Treat with *phentolamine* (alpha-1 antaganist). Blanching of a vein into which norepinephrine is being infused together with induration and pallor of the tissues surrounding the IV site are signs of norepinephrine extravasation and resulting vasoconstriction. Tissue necrosis is best prevented by local injection of an α receptor blocking drug, such as phentolamine.

Hardy-Weinberg equilibrium criteria

Hardy-Weinberg equilibrium Principle Genetic variation (ie, frequencies ofalleles & genotypes) will remain constantin the absence of disturbing factors Criteria Large population size Random mating No natural selection No migration No spontaneous mutations

primary nocturnal enuresis

(ie, bed-wetting at age ≥5 without prior nighttime urinary continence) is caused primarily by a brain maturational delay in the development of bladder control.

pulmonary arterial hypertension tx

*Endothelin-1 antagonists (*Bosentan*)* Prostanoids (*Epoprostenol, iloprost*) Phosphodiesterase 5 inhibitors (*sildenafil, tadalafil*)

a systolic murmur along the left sternal border that decreases in intensity with maneuvers that increase left ventricular (LV) blood volume (hand grip, squating). What happens to LV cavity size, LV muscle mass, EF, LV relaxation)

Hypertrophic cardiomyopathy (HCM) typically involves interventricular septal hypertrophy that obstructs left ventricular (LV) outflow and creates a systolic murmur that decreases in intensity with maneuvers that increase LV blood volume (eg, handgrip, passive leg elevation). HCM is characterized by increased LV muscle mass with a small LV cavity, preserved ejection fraction, and impaired relaxation leading to diastolic dysfunction.

permanent central diabetes insipidus vs. transient central DI

Injury to the hypothalamus or posterior pituitary (eg, head trauma, transsphenoidal neurosurgery, suprasellar masses) can result in central diabetes insipidus (DI). Damage to the posterior pituitary gland typically causes transient DI, whereas damage to the hypothalamic nuclei often causes permanent DI.

in viral infection, what interferons are secreted

Interferons α and β are produced by most human cells in response to viral infections. The production of α and β interferons helps suppress viral replication by halting protein synthesis and promoting apoptosis of infected cells, limiting the ability of viruses to spread through the tissues. Interferon γ is a type II interferon produced mainly by T cells and NK cells. It promotes TH1 differentiation, increases expression of class II MHC molecules on antigen-presenting cells, and improves the intracellular killing ability of macrophages. However, virally infected respiratory epithelial cells would secrete interferons α and β, not interferon γ.

Types of diaper rash

Irritant contact diaper dermatitis is the most common diaper rash and is characterized by skin barrier breakdown as a result of exposure to fecal bacteria that causes increased local skin pH. Treatment is with a barrier ointment that prevents skin contact with urine and stool. Increased hapten sensitization describes allergic contact dermatitis, which is uncommon in the diaper area but can occur with an allergy to a component (eg, dye, fragrance) in diapers or wipes. The rash is unlikely to resolve without complete removal of the offending antigen (eg, changing diaper brand), and topical corticosteroids are also required in many cases. In contrast to candidal diaper dermatitis, another common diaper rash caused by a secondary yeast infection, irritant contact diaper dermatitis does not have skinfold involvement or satellite lesions (ie, discrete lesions beyond the borders of the main rash).

ang II can cause what heart condition

LVH Concentric left ventricular hypertrophy (LVH) is a common complication of chronic hypertension, characterized by uniformly thickened ventricular walls and enlarged cardiomyocytes and nuclei. The vasoconstrictors angiotensin II and endothelin likely have a prominent role in the development of concentric LVH independent of their effects on blood pressure. Angiotensin II receptor blockers are more effective than other antihypertensive agents in reducing LVH.

types of leprosy

Leprosy is a chronic, slowly progressive, communicable disease caused by Mycobacterium leprae that typically involves the skin and peripheral nerves. Clinical manifestations are widely variable depending on the strength of the TH1 cell-mediated immune response to the organism. Disease is classified along a spectrum between tuberculoid (mild) to lepromatous (severe) forms. Patients with tuberculoid leprosy develop a strong TH1-mediated response (interleukin [IL]-2, IFN-γ, and IL-12) in affected tissues, leading to the activation of macrophages that kill M leprae organisms, thereby limiting disease extent. However, this localized inflammation damages the skin and cutaneous nerves, leading to the development of a small number of hypopigmented, well-demarcated plaques with decreased sensation. Lepromatous leprosy is a more disseminated form of the disease characterized by an innate inability to recognize and mount a cellular immune response against M leprae antigens. Affected tissues show extensive accumulation of acid-fast bacilli within macrophages and often a TH2 cytokine profile (IL-4, IL-5, and IL-10). Patients with lepromatous leprosy develop more numerous, poorly demarcated plaques that are widespread across the body. Over time, the bacterial load increases and the nodular lesions coalesce, causing the development of leonine facies and degeneration and loss of the nose and digits.

Dopamine effects at different doses

Low-dose dopamine infusion stimulates D1 receptors in the renal and mesenteric vasculature, resulting in vasodilation and increased blood flow to these sites. Increasing doses of dopamine stimulate β1 and α1 receptors, resulting in increased cardiac output and elevated systemic vascular resistance. At the high end of the dose range, the increase in afterload can result in decreased cardiac output.

Shigella invades what cells?

M cells that overly Peyers patches

Cisplatin, carboplatin

MOA: *Cross-link DNA* Use: Testicular, bladder, ovary, and lung carcinomas Tox: *Nephrotoxicity* - prevent with *amifostine* (free radical scavenger) and chloride (saline) diuresis. *Ototoxocicity*

S-100 tumor marker

Melanoma, schwannomas neural crest origin

midsystolic click followed by a mitral regurgitation murmur

Mitral valve prolapse is most often caused by *defects in connective tissue proteins* that predispose to myxomatous degeneration of the mitral leaflets and chordae tendineae. Cardiac auscultation typically reveals a midsystolic click followed by a mitral regurgitation murmur; the click and murmur occur later in systole or disappear completely with maneuvers (eg, squatting) that increase left ventricular end-diastolic volume.

muscle weakness and myotonia (impaired muscle relaxation) with muscle atrophy, particularly of the type I (slow-twitch) muscle fibers

Myotonic dystrophy - Pathophysiology involves a trinucleotide repeat expansion DMPK causing mutant RNA that disrupts muscle contraction and relaxation.

Niacin can be synthesized from

Niacin (vitamin B3) can be synthesized endogenously from tryptophan and is an essential component of NAD and NADP. A deficiency of this vitamin results in pellagra, which is characterized by dermatitis, diarrhea, and dementia.

NE effects

Norepinephrine stimulates cardiac β1 adrenoreceptors, which increases cAMP concentration within cardiac myocytes and leads to increased contractility, conduction, and heart rate. Peripheral vasoconstriction occurs via stimulation of α1 adrenoreceptors in vascular smooth muscle cells and activation of an IP3 signaling pathway

age related changes of liver

Normal age-related changes in the liver include decreased size, decreased perfusion, slower regenerative capability, and the development of *yellowish-brown lipofuscin inclusions within hepatocytes*

rett syndrome neuropathology

Rett syndrome is a genetic disorder characterized by normal development until age 6-18 months, when regression of speech, loss of purposeful hand movements, development of stereotypical movements, and gait abnormalities occur. Neuropathology shows arrested brain development rather than neurodegeneration.

hyperacusis

The stapedius muscle is innervated by the stapedius nerve (a branch of the facial nerve). Paralysis of the stapedius muscle results in hyperacusis (eg, increased sensitivity to sound).

contralateral hemiballism, characterized by wild, involuntary, large-amplitude, flinging movements of the proximal limbs (eg, arm and/or leg) on one side of the body.

The subthalamic nucleus plays an important role in the modulation of basal ganglia output. Damage to this structure (eg, due to lacunar stroke) may result in this

what causes fever in malaria

Rupture of RBC by schizont to release merozoites Malaria is generally asymptomatic for 1-4 weeks after transmission. Manifestations arise once the pathogen lyses erythrocytes, which releases inflammatory cytokines. Initial manifestations typically include periods of high fever and nonspecific, flu-like symptoms.

How does fibrate increases gallstone formation?

Suppression 7-alpha hydroxyls activity->reduce cholesterol conversion to bile acids->increase cholesterol concentration within bile->more cholesterol than bile, cholesterol percipitates Fibrate medications (eg, fenofibrate, gemfibrozil) inhibit cholesterol 7α-hydroxylase, which catalyzes the rate-limiting step in the synthesis of bile acids. The reduced bile acid production results in decreased cholesterol solubility in bile and favors the formation of cholesterol gallstones.

calcium pyrophosphate crystals

Synovial fluid analysis showing rhomboid-shaped calcium pyrophosphate dihydrate crystals is diagnostic of pseudogout. These crystals are positively birefringent under compensated polarized light. The knee joint is involved in >50% of cases. Pseudogout crystals are blue when aligned parallel and yellow when aligned perpendicular to the slow ray of the compensator.

what happens K+ excretion if aldosterone is not working

Urinary K+ excretion decreases Type 4 renal tubular acidosis (RTA) results from a reduced aldosterone effect on the kidneys and is characterized by hyperkalemia (reduced potassium excretion) and nonanion gap metabolic acidosis (reduced hydrogen excretion in the form of ammonium). Sodium reabsorption is decreased, leading to decreased total body sodium, but the serum sodium concentration is often unchanged due to the appropriate function of antidiuretic hormone.

vascular calcification in CKD

Vascular calcifications occur more commonly in patients with chronic kidney disease due to electrolyte abnormalities (eg, hyperphosphatemia, hypercalcemia) and chronic inflammation (secondary to atherosclerosis and/or uremia). These changes promote calcification and suppress calcification inhibitors, which can result in extensive vascular calcifications.

vasovagal syncope

Vasovagal syncope typically involves a trigger (eg, prolonged standing), a prodrome (eg, warmth, light-headedness), and rapid recovery (eg, within 1-2 min). It results from a transient, autonomic nervous system-mediated cardioinhibitory and vasodepressor response.

viltiigo vs. albinism - melanocyte changes

Vitiligo is a common condition characterized by the loss of epidermal melanocytes. Individuals with albinism have melanocytes that do not produce melanin because of absent or defective tyrosinase.

REM sleep behavior disorder

a parasomnia characterized by dream-enactment behaviors due to a loss of atonia during REM sleep. Patients can usually be awakened fairly easily, are alert and oriented, and can immediately recall their dreams.

Frontal lobe function may be diagnosed by testing

abstraction ability (eg, asking about the similarities between two related objects) on the mental status examination. like difference between a watch and ruler The frontal lobes are involved in personality, language, motor functions, and executive functions (eg, abstraction).

Patients with severe aortic stenosis are at high risk for mucocutaneous and colonic bleeding due to

acquired von Willebrand deficiency. The von Willebrand factor multimers become unfolded by the high shear stress, leading to increased destruction by the ADAMTS13 metalloproteinase.

compared to LV, The right ventricle (RV) is relatively protected from myocardial infarction (MI), and contractile function of the RV usually returns to normal following MI. Why?

actors contributing to this protection include relatively small muscle mass with high capacity to increase oxygen extraction, perfusion throughout the cardiac cycle, and heightened ischemic preconditioning.

Blunt chest trauma can lead to several life-threatening cardiopulmonary injuries. Progressive hypotension with tachycardia, jugular venous distension, and bilateral vesicular breath sounds suggests

acute cardiac tamponade