Uworld17 Flashcards

Question

What is schistosomiasis?

Answer 1

a blood fluke infection that occurs when humans bathe or swim in freshwater that contains contaminated snails. Adult worms mature in the liver, lodge in the mesenteric venules or vesicular venous plexus, and secrete eggs into feces or urine. Eggs can trigger granulomatous inflammation, leading to symptoms in the gastrointesterinal, urinary, or periportal tract. Diagnosis is typically made when round or oval eggs with a terminal or lateral spine are identified in urine, feces, or biospy.

Answer 2

A single brain abscess is usually caused by direct spread of a contiguous infection. Temporal lobe abscess is usually a result of otitis media that has spread to the mastoid air cells, while frontal lobe abscess is usually dye to ethmoid or frontal sinusitis. Multiple brain abscesses typically indicate hematogenous dissemination of a distant infection (eg endocarditis, empyema)

Answer 3

The individual subunits of the hemoglobin molecule are structurally analogous to myoglobin. If separated, the monomeric subunits will demonstrate a hyperbolic oxygen-dissociation curve similar to that of myoglobin

Answer 4

The slow inward calcium current within the atrioventricular node decreases the transmission rate of rapid impulses generated by the atrial myocardium (eg, atrial fibrillation/flutter), acting as a conduction rate buffer between the atria and the ventricles

Answer 5

the intentional falsification of symptoms or induction of illness. The goal is to assume the patient role, and there is no obvious external reward.

Answer 6

activated, pathogen specific cytotoxic T cells or natural killer cells that form in response to certain intracellular infections. In contrast to normal lymphocytes, reactive lymphocytes are large, scalloped, and have abundant cytoplasm. Reactive lymphocytosis is a diagnostic feature of infectious mononucleosis.

Answer 7

Enhancers or silencers may be located upstream, downstream, or within a transcribed gene; these gene sequences function to increase and decrease the rate of transcription, respectively. In contrast, promoter regions are typically located 25 or 75 bases upstream from their associated genes and function to initiate transcription.

Answer 8

With direct-acting antiviral meds such as ledipsavir and sofosbuvir. These meds target specific HCV enzymes (eg, protease, NS5A, RNA polymerase), which inhibits viral replication and assembly. Treatment with DAAs results in cure in >97% of patients.

Answer 9

small to medium sized trials conducted with participants having the condition of interest to assess treatment efficacy, toxicity, adverse effects, and optimal dosing strategies; they are sometimes called pilot studies.

Answer 10

a popular, OTC antitussive agent that acts on sigma receptors to suppress the medullary cough center. DXM also has an off target action on serotonin transports and receptors in the CNS. Overdose or accidental interaction with other serotonergic meds (eg SSRIs, antidepressants) can precipitate serotonin syndrome.

Answer 11

bind the HIV transmembrane glycoprotein gp41 and prevent it from approximating the viral and host cellular membranes, which prevents HIV penetration into new host cells

Answer 12

Electroconvulsive therapy. It is appropriate for severely depressed patients who require rapid intervention (eg, suicidal)

Answer 13

the probability that an individual does not have a disease given a negative test result. It is equal to the number of individuals who do not have the disease and who have a negative test result divided by the total number of individuals with a negative test result NPV= TN / (TN+FN)

Answer 14

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.

Answer 15

Coronary autoregulation allows coronary blood flow to be primarily driven by myocardial oxygen demand over a wide range of perfusion pressures (60-140 mmHg). It is mostly accomplished by alterations in vascular resistance via release of adenosine and nitric oxide in response to myocardial hypoxia.

Answer 16

results when serious fluid accumulates within the tunica vaginalis in the setting of a patent processus vaginalis. It presents as a painless swelling that transilluminates on exam

Answer 17

often presents in adolescents with a mediastinal mass that can cause respiratory symptoms or superior vena cava syndrome. The diagnosis is confirmed via flow cytometry by identifying a population of T lymphoblasts (ie, TdT and CD3+)

Answer 18

Regurgitant flow into the left atrium in acute mitral regurgitation leads to increased left atrial pressure and increased left ventricular end diastolic volume (preload). The low resistance regurgitant pathway also decreases left ventricular afterload with a resulting increase in ejection fraction but overall decrease in forward stroke volume. Increased left atrial pressure and decreased cardiac output result in pulmonary edema and severe hypotension, respectively.

Answer 19

Monoclonal antibodies (mAbs) are not eliminated by hepatic or renal clearance. Therefore, no dose adjustment is necessary with impaired hepatic/renal function or use of cytochrome P450 inducers or inhibitors

Answer 20

Methotrexate and other folic acid antagonists adversely affect rapidly dividing cells (eg, epithelial cells, stem cells, neural tube cells) by limiting the production of precursors essential to DNA synthesis and repair. If used in the first trimester, these drugs can cause major congenital abnormalities (eg cardiovascular abnormalities, neural tube defects)

Answer 21

uroporphyrinogen decarboxylase. Enzyme deficiencies of the early steps in porphyrin synthesis cause neuropsychiatric manifestations without photosensitivity, whereas late step derangements lead to photosensitivity, Photosensitivity manifests as vesicle and blister formation on sun exposed areas as well as edema, pruritis, pain and erythema

Answer 22

The secretory phase of the menstrual cycle occurs between ovulation and menses, from days 15-28 of the normal menstrual cycle. Progesterone released by the corpus luteum causes the uterine glands to coil and secrete glycogen-rich mucus in preparation for embryo implantation. The endometrial stroma becomes edematous and completely traversed by tortuous spiral arteries that extend from the deeper layers to the uterine lumen.

Answer 23

CD8+ T lymphocytes, which are activated through the presentation of viral antigens on infected CD21 B lymphocytes. These reactive (atypical) CD8 T lymphocytes can be observed in the peripheral blood smears of patients with infectious mononucleosis

Answer 24

refers to coinfection of a host cell by 2 viral strains, resulting in progeny virions that contain nucleocapsid proteins from one strain and the unchanged parental genome of the other strain. Because there is no change in the underlying viral genomes (no genetic exchange), the next generation of virions revert to their original, unmixed phenotypes.

Answer 25

Cystic fibrosis causes the accumulation of thick, viscous secretions in ducts throughout the body. CF-related diabetes occurs after the progressive destruction of pancreatic islet cells leads to decreased insulin production

Answer 26

portal hypertension, splenomegaly, and varicosities at portocaval anastomoses. It does not cause histologic changes to the hepatic parenchyma. Ascites is uncommon as the obstruction is presinusoidal; ascites typically only develops in conditions that cause sinusoidal hypertension.

Answer 27

retrograde urine flow from the bladder into the ureter. Affected patients are at increased risk of chronic pyelonephritis and subsequent renal scarring (eg, dilated calyces with overlying cortical atrophy)

Answer 28

Infant botulism can result from the consumption of honey, which frequently contains C botulinum spores. Symptoms include constipation, mild weakness, lethargy, poor feeding and in severe cases, flaccid paralysis. The diagnosis can be confirmed by identification of C botulinum spores or toxins in the stool.

Answer 29

work by interfering with the 30S ribosomal subunit and causing the cell to misread messenger RNA, thereby halting protein synthesis. An important mechanism of resistance is the methylation of the aminoglycoside-binding portion of the ribosome, which inhibits the ability of aminoglycoside to interfere with protein translation

Answer 30

contralateral weakness of the arm and leg with ipsilateral facial weakness. Facial weakness occurs in a lower motor neuron pattern (ipsilateral, affects upper face) because the damage occurs at the level of the facial nerve (CNVII) origination

Answer 31

increased central venous pressure, which is transmitted to the hepatic sinusoids, leading to increased capillary hydrostatic pressure. Capillary permeability is unaffeced. Although chronic passive congestion may eventually result in hepatic synthetic dysfunction (hypoalbuminemia) with low oncotic pressures, the oncotic pressure will remain normal for several weeks at least.

Answer 32

due to NADPH oxifase deficiency, which leads to an inability of neutrophils to generate a respiratory burst and produce the reactive oxygen species necessary to kill organisms in their phagolysosomes. Absence of fluorescence on dihydrorhodamine flow cytometry testing can confirm the diagnosis

Answer 33

patchy dense collagen fibrosis in the interstitium, focal fibroblastic proliferation, honeycombing, and mild lymphoplasmacytic infiltrates with hyperplasia of type 2 pneumocytes. Therapies are directed at slowing the progression of fibrosis by inhibiting transforming growth factor-beta and other fibrogenic growth factors (eg, PDGF, fibroblastic growth factor, and VEGF)

Answer 34

a common cause of secondary amenorrhea and occurs due to decreased amplitude and frequency of pulsatile gonadotropin-releasing hormone release from the hypothalamus, which in turns leads to low FSH, LH, and estrogen levels. Causes include anorexia nervosa (eg, distorted body image, restricted diet, lanugo), excessive strenuous exercise and chronic illness

Answer 35

equimolar amounts of dextrose (glucose) and sodium, which are absorbed through intestinal cotransport to maintain intravascular volume status. They also contain potassium to compensate for gastrointestinal losses, and citrate to buffer metabolic acidosis.

Answer 36

metastasis from another primary site (eg, breast, lung, colon); primary liver neoplasms (eg, hepatocellular carcinoma) are much less common

Answer 37

hyperkeratosis and confluent parakeratosis of the stratum corneum, and epidermal hyperplasia (acanthuses) with elongated rete ridges. Neutrophilic foci in the stratum corneum and epidermis may coalesce to form microabscesses (Munro micro abscesses)

Answer 38

defective cystine reabsorption by proximal renal tubular epithelial cells. It most often presents with recurrent stone formation at a young age. UA shows pathognomonic hexagonal cystine crystals, and the sodium cyanide-nitroprusside test can be used to detect excess cystine in the urine

Answer 39

on cell cycle regulatory proteins p53 and Rb. This allows cells infected with HPV to undergo unchecked cellular proliferation and evasion of apoptosis, promoting genomic instability and malignant transformation

Answer 40

characterized by numbness of the 4th and 5th digits, pain, and weakness. Most commonly caused by compressive injury, leading to tissue ischemia and demyelination (Schwann cell injury). A nerve conduction study can help differentiate demyelinating versus axonal neuropathies; demyelination causes slowed or blocked nerve conduction velocity whereas axonal injury leads to a reduction in signal strength.

Answer 41

deltaF508 is the most common mutation in the cystic fibrosis transmembrane regulator (CFTR) protein in patients with cystic fibrosis. This mutation leads to protein misfolding and failure of glycosylation, followed by proteasome-mediated degradation and significantly decreased number of transmembrane CFTR proteins

Answer 42

results from endothelial dysfunction that leads to an increase in vasoconstrictive, proproliferative mediators (eg, endothelin, thromboxane A2) and a decrease in vasodilative, antiproliferative mediators (eg, nitric oxide, prostacyclin). The relative imbalance in these mediators leads to vasoconstriction and intimal wall thickening with a consequent increase in pulmonary vascular resistance.

Answer 43

mononucleosis like symptoms (fever, lymphadenopathy, sore throat) 2-4 weeks after transmission. Important diagnostic clues are oropharyngeal ulcers and a diffuse maculopapular rash. As the humoral antibody response is not fully activated early in infection, lab results typically show HIV in the serum (positive viral load and p24 antigen) but negative HIV serology.

Answer 44

describes the difference in risk between control and treatment groups ARR= risk(control) - risk(treatment)

Answer 45

Although children understand the concept of gender by age 4, it is normal for them to explore activities culturally associated with the opposite gender. In contrast, gender dysphoria is diagnosed when there is marked distress associated with a prolonged and intense feeling that one is different gender from one's birth sex.

Answer 46

In chronic kidney disease, conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D is impaired. In addition, failure of glomerular and tubular function results in phosphate retention and hypocalcemia. This leads to a compensatory rise in parathyroid hormone (secondary hyperparathyroidism) that can present with weakness, muscle and joint pain, defective bone mineralization, and increased fracture risk.

Answer 47

a systemic vasculitis of medium sized muscular arteries marked by segmental, transmural, arterial wall inflammation with fibrinoid necrosis. This narrows the arterial lumen and increases risk of thrombosis and tissue ischemia/infarction. Damage to the internal and external elastic laminae also increases the risk of microaneurysm. Tissue damage primarily occurs in the kidney, GI tract, neurologic system, and skin; the lungs are usually spared.

Answer 48

An abnormal BMPR2 gene predisposes affected individuals to excessive endothelial injury and smooth muscle cell proliferation. An insult (eg infection, drugs) is thought to then activate the disease process, resulting in vascular remodeling, increased pulmonary vascular resistance, and progressive pulmonary hypertension

Answer 49

A known complication of vaccine adminstration, particularly in adolescents. It typically involves a prodrome and can be differentiated from anaphylaxis based on skin findings (pallor vs urticaria), absence of respiratory symptoms (eg, upper airway edema, bronchospasm), and presence of bradycardia (vs tachycardia)

Answer 50

the absolute neutrophil count due to the risk of life threatening agranulocytosis

Answer 51

Isoniazid inhibits phosphokinase, leading to impaired activation of pyridoxine (vitB6). Pyridoxine is a cofactor for aminolevulinic acid synthase, the enzyme that catalyzes the rate limiting step of heme synthesis. Inhibition of this step can result in sideroblastic anemia

Answer 52

the anterior cervical (ie, jugular) lymph nodes via the lymphatics. Distant spread occurs after regional lymph node involvement

Answer 53

Intravenous regular insulin has a rapid onset and short half life, allowing the rapid adjustments needed in diabetic ketoacidosis management, In contrast, regular insulin given subcutaneously starts working within 30 min, peaks 2-4 hours, and last 5-8 hours, making it usable as a premeal insulin that treats postprandial hyperglycemia

Answer 54

oxidase+, nonlactose fermenting, G- rod It is a common cause of urinary tract infections in patients with indwelling bladder catheters

Answer 55

reduced lung function that persists for months or years and is sometimes permanent. The majority of patients have reduced diffusion capacity that eventually normalizes after several years, whereas a small percentage develop extensive fibrosis with a marked and permanent reduction in diffusion capacity

Answer 56

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. chronic chagas cardiomyopathy is characterized by localized apical wall thinning with large apical aneurysm development

Answer 57

air or gas in the peritoneal cavity; it can be seen as free air under the diaphragm in an upright chest xray. The most common cause is a perforated duodenal ulcer, but perforation can occur anywhere along the gastrointestinal (or female reproductive) tract. Subsequent peritonitis can lead to diffuse abdominal pain with rebound and guarding, sometimes with referred shoulder pain due to diaphragmatic irritation

Answer 58

the length constant and the time constant (ie, velocity= length/time). Myelination increases the length constant and decreases the time constant, both of which improve axonal conduction speed. Demyelination thus impairs stimulus transmission.

Answer 59

development of aortic aneurysms. Medial degeneration in younger individuals is frequently due to Marfan syndrome.

Answer 60

progesterone antagonist that is used with misoprostol (a prostaglandin-E1 agonist) to terminate a first-trimester pregnancy

Answer 61

the presence of endometrial glands and stroma in an extrauterine location. Ectopic implants within the intraperitoneal cavity degenerate during menses and can cause abdominopelvic inflammation and the formation of tissue adhesions. Therefore, patients with endometriosis may have dysmenorrhea, dyspareunia, and infertilty

Answer 62

Contraction initiation in cardiac and smooth muscle cells is dependent on extracellular calcium influx through L-type calcium channels, which can be prevented by calcium channel blockers (eg, verapamil). Skeletal muscle is resistant to calcium channel blockers, as calcium release by the sarcoplasmic reticulum is triggered by a mechanical interaction between L-type and RyR calcium channels

Answer 63

Patients with Crohn disease affecting the terminal ileum (most common site of involvement) are prone to developing gallstones. Decreased bile acid reabsorption by the inflamed terminal ileum promotes cholesterol supersaturation of the bile, resulting in gallstone formation.

Answer 64

caused by dysfunctional androgen receptors; genotypic males (XY) have testes but no external male genitalia or internal male genital ducts (eg, vas deferent) due to the lack of androgen effect during fetal development. Instead, external female genitalia develop, but antimullerian hormone results in the absence of internal female genital ducts (eg, fallopian tubes) as well

Answer 65

sustained renal hypoperfusion and result in acute tubular necrosis. ATN presents with oliguria, increased serum creatinine, and blood urea nitrogen/creatinine ratio <20:1 UA: muddy brown granular casts composed of sloughed renal tubular epithelial cells

Answer 66

Restless legs syndrome is characterized by an uncomfortable sensation in the legs accompanied by an urge to move them; symptoms worsen with inactivity and at night and are temporarily relieved with movement. Alpha-2-delta calcium channel ligands (eg, gabapentin, pregabalin) and dopamine agonists (pramipexole) can be used to treat persistent symptoms

Answer 67

G+, lancet shaped diplococcus that is catalase negative, alpha hemolytic, optochin sensitive, and bile soluble

Answer 68

optochin resistant and bile insoluble

Answer 69

beta hemolytic and PYR positive and appears as G+ cocci in chains

Answer 70

HFE protein mutations are the most common cause of primary hemochromatosis. Inactivation of the HFE protein results in decreased hepcidin synthesis by hepatocytes and increased DMT1 expression by enterocytes, leading to iron overload. Patients with hemochromatosis are at an increased risk for liver cirrhosis and hepatocellular carcinoma

Answer 71

Multiple myeloma, a plasma cell malignancy associated with significant production of secretory proteins (eg monoclonal immunoglobulins), is frequently treated with proteasome inhibitors (eg bortezomib). These drugs block the degradation of ubiquitinated proteins by the proteasome, which leads to accumulation of abnormally folded proteins that trigger cellular apoptosis

Answer 72

a slow growing, stable atherosclerotic plaque. An unstable atherosclerotic plaque (eg that with active inflammation, a lipid rich core, thin fibrous cap) is more likely to rupture, resulting in the abrupt onset of ischemia/infarction that precludes the development of viable collateral vessels

Answer 73

HPV infection of basal cervical epithelial cells can cause dysplasia known as cervical intraepithelial neoplasia. CIN is low grade (if involving the lower one third of the epithelium) or high grade (if extending above the lower 1/3) Basement membrane invasion signifies invasive cancer.

Answer 74

Subserosal uterine leiomyomas (fibroids) can cause irregular uterine enlargement and bulk related symptoms (pelvic pressure) Posterior leiomyomas can cause constipation due to pressure on the colon.

Answer 75

Pregnant patients have marked increases in blood plasma volume (by 30-50%) and red blood cell mass (by 20-30%), which helps improve fetal nutrient delivery while also protecting against excessive blood loss during delivery. Because the expansion of blood plasma volume is greater than the increase in red blood cell mass, pregnant women typically have mildly decreased hemoglobin concentrations (ie, dilutional anemia)

Answer 76

Organogenesis occurs in the embryonic stage of development (3-8 weeks after fertilization), during which time the embryo is susceptible to teratogens. Neuralation (neural tube formation) occurs during weeks 3 and 4, and abnormalities in this process result in neural tube defects

Answer 77

loss of an X chromosome, most often due to meiotic nondisjunction during gametogenesis