Uworld 7

Question 1

Poststreptococcal glomerulonephritis occurs after exposure to?

Answer 1

Strains of group A streptococcus that produce nephritogenic antigens; antigen-antibody complexes deposit on the glomerular basement membrane and activate the alternate complement pathway.

Question 2

What is seen on IF for poststreptococcal glomerulonephritis?

Answer 2

Granular deposits of IgG, IgM, and C3 in the basement membranes and mesangium.

Question 3

When does intestinal malrotation occur?

Answer 3

When the midgut undergoes incomplete counterclockwise rotation during embryologic development

Question 4

How does intestinal malrotation present?

Answer 4

In the neonatal period with biliois emesis due to extrinsic duodenal compression by Ladd bands or due to midgut volvulus with intestinal ischemia.

Question 5

How does antibiotics alter the normal vaginal flora?

Answer 5

Antibiotics use alters the balance of normal vaginal flora (eg, decrease the number of gram+ lactobacilli and facilitates Candida overgrowth.

Patients can develop vulvovaginal candidiasis, which presents with vulvar/vaginal/perianal pruiritis; erythema; and a thick, white vaginal discharge.

Question 6

Pudendal nerve injury can occur due to?

Answer 6

Excessive stress on the pelvic floor during labor and delivery (eg, prolonged second stage).

Nerve injury leads to denervation and weakness of the perineal musculature (eg, external anal sphincter), which can present as new-onset fecal incontinence.

Question 7

Homecystinuria is most commonly caused by?

Answer 7

Cystathionine synthase deficiency.

Affected individuals have marfanoid habitus, ectopia lentis, and developmental delay.

Question 8

What is the significant morbidity and mortality for homocystinuria?

Answer 8

Due primarily to thromboembolism.

Many patients with homocystinuria respond dramatically to pyridoxine (vitamin B6) supplementation.

Question 9

How is GFR estimated in common practice?

Answer 9

GFR is estimated using creatinine clearance.

However, creatinine is actively secreted by the proximal tubules, so uncorrected creatinine clearance overestimates the GFR by approximately 10%-20%.

Question 10

What is atrophy?

Answer 10

A cellular adaptation characterized by a decrease in cell size and number, leading to decreased organ size.

Pathologic atrophy physical workload, loss of innervation, decreased blood supply, inadequate nutrition, absent endocrine stimulation, aging, and mechanical pressure.

Question 11

Testosterone replacement therapy is indicated for men with?

Answer 11

Symptomatic hypogonadism.

It is associated with an increase in serum prostate-specific antigen and may raise the risk of prostate cancer.

In addition, testosterone therapy can cause erythrocytosis (leading to thromboembolism), and hematocrit should be regularly monitored.

Question 12

What causes the green discoloration of pus/sputum?

Answer 12

Green discoloration of pus/sputum seem during common bacterial infections is due to the presence of myeloperoxidaase, a blue-green heme-based enzymes that is released from neutrophil azurophilic granules and forms hypochlorous acid (bleach).

Question 13

What is the MOA of glucocorticoids?

Answer 13

Inhibit transcription of proinflammatory mediators and promote apoptosis of eosinophils, T cells, and monocytes

Question 14

What is stimulant withdrawal is characterized by?

Answer 14

Dysphoric mood, fatigue, hypersomnia, hyperplasia, and vivid dreams.

Stimulant withdrawal is not associated with significant findings on PE.

Question 15

What steps are required before finalized mRNA molecules?

Answer 15

When mRNA is first transcribed from DNA, it is an unprocessed form called pre-mRNA or heterogeneous nuclear mRNA (hnRNA).

Several processing steps are required before finalized mRNA molecules can leave the nucleus, including 5’-capping, poly A tail addition, and intron splicing.

Cytoplasmic P bodies an important role in mRNA translation regulation and mRNA degradation.

Question 16

Name the seronegative spondyloarthropathies associated with inflammatory bowel disease

Answer 16

Ankylosing spondylitis, reactive arthritis, psoriatic arthritis, and arthritis.

Individuals expressing HLA B27 (a specific HLA class I molecule) are at increased risk for seronegative spondylarthropathies.

Question 17

The chemotherapeutic effet of methotrexate is overcome by?

Answer 17

Overcome by N5-formyl-tetrahydrofolate (folinic acid, leucovorin) supplementation

Question 18

Methotrexate and 5-FU both inhibit what?

Answer 18

Inhibit thymidylate formation

Question 19

What are the primary mediators of disease in chronic obstructive pulmonary disease?

Answer 19

Neutrophils, macrophages, and CD8+T lymphocytes.

They secrete enzymes and proteases that cause and perpetuate both the alveolar destruction of emphysema and the mucus hypersecretion found in chronic bronchitis.

Question 20

Midshaft fractures of the humerus risk injury to what?

Answer 20

The deep brachial (profunda brachii) artery and radial nerve run together along the posterior aspect of the humerus

Question 21

V3 Mandibular branch of trigeminal nerve innervates what muscles?

Answer 21

The muscles of mastication: masseter, the medial and lateral pterygoids, and the temporalis muscle.

Question 22

V3 mandibular branch of trigemal nerve exits the skull through?

Answer 22

Foramen ovale

Question 23

Classic triad for acute bacterial meningitis? evaluation?

Answer 23

fever, stiff neck, and altered mentation

Evaluation requires prompt blood cultures, empiric antibiotics, and lumbar puncture with cerebrospinal fluid analysis

Question 24

What is the mechanism of reperfusion injury?

Answer 24

Reperfusion injury is thought to occur secondary to oxygen free radical generation, mitochondrial damage, and inflammation.

Question 25

IV drug users are at increased risk for what?

Answer 25

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

Question 26

Amyotrophic lateral sclerosis can cause?

Answer 26

Causes degeneration of both upper and lower motor neurons and can result in bulbar and skeletal muscle weakness. Denervation atrophy can affect the diaphragm and contribute to respiratory failure.

Question 27

What is fluorescence in situ hybridization (FISH) used for?

Answer 27

FISH can identify specific chromosomal translocations, duplications, or deletions using a single-stranded, complementary DNA segment that is tagged with a radiotracer. FISH is rapid, highly sensitive and specific, and can be used on tissues with low mitotic rates. However, the targeted chromosomal abnormality must be somewhat large in order to be identified.

Question 28

What happens to the O2 and Co2 levels in the body during exercise?

Answer 28

During physical exercise, there is increased skeletal muscle CO2 production that increases the CO2 content of venous blood. Arterial O2 and CO2 content remains constant via increases in alveolar ventilation and gas exchange efficiency. Venous O2 content remains constant or is decreased due to increased O2 extraction by the tissues that matches or exceeds the rate of oxygen delivery (ie, O2 consumption during exercise is limited by cardiac output)

Question 29

Overuse/abuse of loop diuretics (eg, furosemide) will show what on electrolyte panel?

Answer 29

Hypokalemic, hypochloremic metabolic alkalosis. Urine electrolytes findings depend on how recently the diuretic was last ingested, increased urine Na, Cl and K are expected with recent ingestion

Question 30

What is MOA behind cough secondary to ACE inhibitor therapy?

Answer 30

Cough secondary to ACE inhibitor therapy is characterized as dry, nonproductive, and persistent. The mechanism behind ACE inhibitor induced cough is accumulation of bradykinin, substance P, or prostaglandins.

Question 31

How does allogeneic hematopoietic stem cell grafts initiate graft versus host disease?

Answer 31

Allogeneic hematopoietic stem cell grafts normally induce donor CD3+T cells that can initiate graft versus host disease, a widespread inflammatory response that can damage multiple organs. Depletion of donor CD3+T cells prior to transplant decreased the risk of GVHD but also decreased the beneficial graft versus tumor effect, increasing the likelihood of cancer relapse.

Question 32

What are quick clinical tests to assess attention and concentration?

Answer 32

Counting down from 100 by intervals of 3 or 7, reciting the months of the year in reverse order, and spelling "world" backwards.

Question 33

Drugs that should be used with caution in geriatric patients

Answer 33

Anticholinergics (eg first-gen antihistamines), centrally acting alpha-2 agonists, tricyclic antidepressants, benzodiazepines (and other sedating meds), antipsychotics, many antiarrhythmics (eg, digoxin), and skeletal muscle relaxants.

Question 34

Injury to the C5 and C6 nerve roots causes what?

Answer 34

Erb-Duchenne palsy: waiter's tip posture. The affected arm may have decreased/absent Moro and biceps reflexes; grasp reflex remains intact.

Question 35

What is acute respiratory distress syndrome?

Answer 35

A severe inflammatory reaction that occurs in the lungs and results in hypoxemia and noncardiogenic pulmonary edema. Pulmonary injury leads to an inflammatory response resulting in breakdown of the capillary-alveolar barrier (created by type 1 pneumocytes and endothelial cells), increased capillary permeability, intraalveolar fluid accumulation, and hyaline membrane formation.

Question 36

In patients with cirrhosis, hyperestrinism can cause?

Answer 36

gynecomastia, spider angiomata, loss of sexual hair, testicular atrophy and palmar erythema.

Question 37

What is the greatest complication of a hookworm infection?

Answer 37

Hookworms are transmitted when human skin comes into contact with soil contaminated with human feces. The larvae penetrate the skin, travel to the lungs, are coughed up, and then swallowed. Adult hookworms live in the small intestine and feed on human blood. Therefore, chronic iron deficiency anemia (microcytic anemia) is the greatest complication.

Question 38

What is the function of Inhibin B?

Answer 38

Inhibin B, produced by heat-sensitive Sertoli cells, is a physiologic inhibitor of FSH secretion.

Question 39

In patients with cryptorchidism what happens to the levels of reproductive hormones?

Answer 39

atrophy of Sertoli cells results in decreased inhibin B, and in turn will elevate FSH. Leydig cell function is not significantly affected, so testosterone and LH are typically normal.

Question 40

What is primary adrenal insufficiency?

Answer 40

Characterized by weight loss, abdominal pain, fatigue, and hyperpigmentation. Physiologic stress in patients with PAI can trigger acute adrenal crisis (eg fever, shock, mental status changes)

Question 41

What is the most common cause of primary adrenal insufficiency?

Answer 41

Autoimmune adrenalitis is the most common cause of PAI and leads to bilateral adrenal atrophy.

Question 42

What is diabetic gastroparesis?

Answer 42

Diabetic gastroparesis results from the destruction of enteric neurons due to chronic hyperglycemia, leading to impaired relaxation and disordered and ineffective peristalsis. This causes delated gastric emptying, which presents as postprandial fullness, regurgitation of undigested food, nausea, and vomitting.

Question 43

MOA of etomidate

Answer 43

Etomidate, a GABA agonist, is often used for anesthesia induction to provide sedation and amnesia. It is hemodynamically neutral, but it can result in transient adrenocortical suppression because it inhibits cortisol synthesis.

Question 44

What is vitiligo?

Answer 44

Vitiligo is a common condition characterized by the loss of the epidermal melanocytes. It occurs more commonly in patients with autoimmune disorders (eg, autoimmune thyroiditis, type I diabetes) and results in well-defined, variably sized patches of hypopigmentation.

Question 45

X-linked agammaglobinemia is characterized by?

Answer 45

low or absent circulating mature B cells (ie, CD 19,20,21 cells) and pan-hypogammaglobinenmia. Affected patients have increased susceptibility to pyogenic bacteria, enteroviruses, and Giardia lamblia due to the absence of opsonizing and neutralizing antibodies.

Question 46

Inheritance pattern for sickle cell disease

Answer 46

Autosomal recessive disorder characterized by a predominance of hemoglobin S, causing red blood cells to sickle, hemolyze, and cause vascular obstruction.

Question 47

Early embryonic development is described in weeks postfertilization (ie, approximate time of ovulation), and major events during this time include implantation (week 1), grastrulation (week 3), and neurulation (week 4). As neurulation occurs, neuroectodermal cells differentiate into?

Answer 47

Into neural crest cells, which then migrate to distant sites during week 5 postfertilization.

Question 48

HPV has a tropism for what type of cells?

Answer 48

Human papilloma virus is s small DNA virus with a tropism for stratified squamous epithelium, which protectively lines anatomical areas that undergo frequent friction and abrasion, including true vocal cords, cervix, and anus. Infants can acquire respiratory papillomatosis via passage through an HPV-infected birth canal.

Question 49

What is Lynch Syndrome due to?

Answer 49

AD disorder caused by abnormal nucleotide mismatch repair. The mismatch repair system involves several genes, including MSH2 and MLH1, which code for components of the human MutS and MutL homologs. Mutations in these 2 genes account for around 90% of cases of Lynch syndrome.

Question 50

Edema formation in nephrotic syndrome occurs due to?

Answer 50

A combination of intravascular underfilling and overfilling. Underfilling results from hypoalbuminemia, which decreases plasma oncotic pressure and results in sodium retention (ie, secondary sodium retention). Overfilling results from sodium retention due to primary defects in renal sodium handling (ie, primary sodium retention).

Question 51

How does glucagonoma present?

Answer 51

With hyperglycemia (often as newly diagnosed diabetes mellitus) and necrolytic migratory erythema (blistering erythematous plaques with central clearing) affecting the groin, face, and extremities. Dx is made by detecting elevated glucagon levels.

Question 52

What is the function of ghrelin?

Answer 52

Stimulates appetite and promotes weight gain.

Question 53

What does leptin and insulin function in terms of appetite?

Answer 53

Leptin and insulin act in the CNS to decrease appetite.

Question 54

Caloric restriction will cause what to happen to ghrelin, insulin, and leptin?

Answer 54

Caloric restriction leads to increased ghrelin levels along with decreased insulin and leptin levels, causing an increase in appetite that can make it difficult to maintain weight loss

Question 55

Sarcoidosis is characterized by?

Answer 55

Noncaseating granulomas due to dysregulated cell-mediated immunity. Activated antigen-presenting cells produce IL-12, which stimulates the differentiation of Th1-type CD4 cells. Th1 cells produce IL-2 and interferon-gamma, which stimulate Th1 cell proliferation and macrophage activation, respectively.

Question 56

Individuals who are successfully immunized against Hep B will show what serological marker?

Answer 56

will have protective anti-HBs antibody.

Question 57

Individuals who recover from hep B infection will have which serological markers?

Answer 57

anti-HBs and anti-HBc antibodies

Question 58

The presence of circulating HBsAg means what?

Answer 58

active infection

Question 59

The common cardinal veins of the developing embryo drain directly into?

Answer 59

Into the sinus venosus

Question 60

The cardinal veins give rise to?

Answer 60

the superior vena cava

Question 61

Helicobacter pylori antral gastritis is associated with the formation of what?

Answer 61

Duodenal ulcers due to increased gastric acid production. This increase in acidity is caused by unchecked gastrin production due to the destruction of somatostatin-secreting cells in the gastric antrum.

Question 62

Norovirus is the most common cause of?

Answer 62

Viral gastroenteritis. Outbreaks in crowded settings (eg, schools, cruise ships, nursing homes) are common, and symptoms: vomitting and watery diarrhea

Question 63

What is the Warburg effect?

Answer 63

Rapidly dividing cells such as stem cells and cancer cells generate energy through anaerobic glycolysis (Warburg effect). This pathway converts the majority of glucose to lactate despite the presence of adequate oxygen to run oxidative phosphorylation. Therefore, cancer cells generally produce far more lactate than a normal terminally differentiated cell.

Question 64

How do human acquire schistosomiasis?

Answer 64

Via contact with freshwater sources that contain snails infected with Schistosoma larvae. S japonicum and S mansoni cause intestinal and hepatic schistosomiasis, and S haematobium causes urinary schistosomiasis.

Question 65

Congenital hypothyroidism is usually asymptomatic at birth. After maternal T4 wanes, infants develop?

Answer 65

constipation, lethargy, hypotonia, macroglossia, an umbilical hernia, and a large anterior fontanelle.

Question 66

What is FOXP3?

Answer 66

FOXP3 is a transcriptional regulator protein that is required for the development of regulatory T cells; it triggers production of cytokines (eg, IL-10, transforming growth factor-beta) and ligands (eg, cytotoxic T-lymphocyte antigen-4) that suppress immune activation.

Question 67

FOXP3 mutations result in?

Answer 67

Immune dysregulation marked by excessive immunoglobin production and the development of autoimmunity.

Question 68

How does a permanent pacemaker placement cause tricuspid regurgitation?

Answer 68

Severe tricuspid valve regurgitation can lead to right-sided heart failure, evidenced by jugular venous distention, hepatomegaly, lower extremity edema, and the absence of pulmonary edema. Permanent pacemaker placement can cause TR because the right ventricular lead passes through the tricuspid valve orifice and can disrupt valve closure.

Question 69

Genetic variations created during Hep C replication result in?

Answer 69

Result in marked variety in the antigenic structure of GCV envelope proteins. The production of host antibodies lag behind that of new mutant HCV strains, preventing infected individuals from mounting an effective immune response.

Question 70

What can be useful for chemotherapy-induced vomitting?

Answer 70

5-HT3 serotonin and neurokinin 1 receptor antagonists

Question 71

What does an abdominal aortic aneurysm lead to?

Answer 71

Abdominal aortic aneurysm is associated with risk factors (eg, age>60, smoking, hypertension, males, family hx) that lead to chronic transmural inflammation and extracellular matrix degradation within the wall of the aorta. This leads to weakening and progressive expansion of the aortic wall, resulting in aneurysm formation, typically below the renal arteries.

Question 72

What is cardiac output according to the Fick principle?

Answer 72

cardiac output = rate of O2 consumption / arteriovenous O2 content difference

Question 73

What is chronic lymphocytic leukemia?

Answer 73

A lymphoproliferative disorder marked by the progressive accumulation of mature B cells. Most patients are asymptomatic for years but eventually develop anemia, thrombocytopenia, and/or neutropenia.

Question 74

How is the diagnosis of chronic lymphocytic leukemia made?

Answer 74

Generally made when complete blood count reveals dramatic leukocytosis with B-cell markers such as CD19,20,23

Question 75

Niacin (vitamin b3) can be synthesized endogenously from?

Answer 75

Tryptophan and is an essential component of NAD and NADP. Deficiency results in pellagra: dermatitis, diarrhea, and dementia

Question 76

MOA of labetalol?

Answer 76

A nonselective vasodilatory beta blocker that blocks beta 1, beta 2, and alpha 1 adrenergic receptors. Alpha 1 receptor blockade outweighs beta 2 receptor blockade to cause peripheral vasodilation with decreased venous return and lower systemic vascular resistance. The relatively balanced vasodilation reduces blood pressure without changing stroke volume. Beta-1 receptor blockade overrides the expected baroreflex-mediated increase in heart rate, resulting in overall decreased heart rate.

Question 77

Malabsorption caused by celiac disease can lead to vitamin D deficiency. Patients will have what on labs?

Answer 77

Patients have decreased serum phosphorus, increased serum parathyroid hormone (secondary hyperparathyroidism), and low (or normal) serum calcium.

Question 78

What is essential to normal wound healing?

Answer 78

Fibroblast and vascular proliferation (ie, granulation tissue) induced by vascular endothelial growth factor (VEGF) is essential to normal wound healing. However, if this tissue proliferation becomes excessive (eg, in wounds left to heal by secondary intention), the resulting hypergranulation tissue can impair wound reepithelization and remodeling

Question 79

What is urticaria?

Answer 79

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

Question 80

Indirect inguinal hernias protrude through?

Answer 80

The deep inguinal ring into the inguinal canal lateral to the inferior epigastric vessels.

Question 81

Direct inguinal hernias protrude through?

Answer 81

Hesselbach's triangle medial to the inferior epigastric vessels.

Question 82

With moderate to heavy exercise, the changes to the left ventricular pressure-volume loop include increased preload and increased contractility that both contribute to increased stroke volume. Although reduced systemic vascular resistance decreases afterload, the increase in systolic pressure caused by increased preload and contractility override the decrease, resulting in overall increased afterload.

Question 83

MOA of cocaine

Answer 83

A stimulant that inhibits the presynaptic reuptake of norepinephrine, dopamine, and serotonin. Also a potent vasoconstrictor that can cause myocardial ischemia and atrophy of the nasal mucosa and septum. Intoxication: agitation, tachycardia, HTN, and light responsive mydriasis due to increased sympathetic activity.

Question 84

What is important in the pathophysiology of metabolic alkalosis?

Answer 84

Total body chloride depletion. Measurement of urine chloride can be helpful in determining the underlying cause.

Question 85

What can C diffucule infection be treated with?

Answer 85

Oral fidaxomicin or oral vancomycin.

Question 86

What the the MOA of fidaximicin?

Answer 86

Macrolide antibiotic that inhibits RNA polymerase. It is bactericidal against C diff.

Question 87

Characteristics of a cerebellar tremor

Answer 87

Classically low frequency (<5 Hz) and high amplitude and increase as an action approaches a target. They are often accompanied by other cerebellar signs, including ataxia, dysmetria, and impaired rapidly alternating movements.

Question 88

What is alpha-1 antitrypsin?

Answer 88

A serum protein that inhibits neutrophil elastase, thereby reducing tissue damage caused by inflammation.

Question 89

Patients with alpha-1 antitrypsin def will develop?

Answer 89

Early-onset emphysema; those with specific mutations (including the Z allele) are also at risk for liver disease due to accumulation of unsecreted, polymerized AAT (reddish-pink globules on periodic acid-Schiff stain) in the periportal hepatocytes.

Question 90

Closed spinal dysraphism (spina bifida occulta or closed neural tube defect) presents how? Pathogenesis?

Answer 90

Often presents with cutaneous lumbosacral findings (eg, deep pit, hemangioma, tuft of hair) in the newborn period. Pathogenesis involves failure of vertebral arch fusion, and imaging may suggest an underlying tethered cord (eg, low lying conus medullaris, thickened filum terminale)

Question 91

Lobar pneumonia is marked by?

Answer 91

The cytokine-mediated accumulation of neutrophils and proteinaceous material in the alveoli. Over several days, the proteinaceous material becomes fibrinous, neutrophils are replaced by macrophages and macrophages digest the fibrinous exudate, thereby restoring normal lung histology.

Question 92

What is locus heterogeneity?

Answer 92

Describes when a similar phenotype is produced by mutations in different genetic loci (eg, oculocutaneous albinism)

Question 93

Function of the supraspinatus muscle?

Answer 93

Assists in abduction of the arm and stabilization of the glenohumeral joint

Question 94

What is the most common cause of rotator cuff syndrome?

Answer 94

Supraspinatus tendinopathy. The supraspinatus tendon is vulnerable to injury due to impingement between the acromion and the head of the humerus

Question 95

Riboflavin is a precursor for which coenzymes?

Answer 95

FMN and FAD. FAD participates in the tricarboxylic acid cycle and electron transport chain by acting as an electron acceptor for succinate dehydrogenase (complex II), which converts succinate into fumarate.

Question 96

Acute promyelocytic leukemia is the M3 variant of acute myelogenous leukemia. It is associated with?

Answer 96

It affects adults and associated with disseminated intravascular coagulation.

Question 97

What is the cytogenetic abnormality for acute promyelocytic leukemia?

Answer 97

t(15;17); leads to formation of the promyelocytic leukemia-retinoic acid receptor alpha (PML/RARa) fusion gene, which is unable to signal for proper cellular differentiation, unlike the normal retinoic acid receptor.

Question 98

Where does perfusion pressure decrease?

Answer 98

Perfusion pressure decreases distal to a significant coronary artery stenosis, resulting in an initial decrease in blood flow. Coronary autoregulation stimulates arteriolar vasodilation, which reduces downstream vascular resistance and helps return blood flow to near-normal levels to prevent myocardial ischemia.

Question 99

What is a frequent source of retroperitoneal bleeding?

Answer 99

Retroperitoneal hematoma is a common complication of blunt abdominal trauma. The pancreas is a retroperitoneal organ, and pancreatic injury is frequently a source of retroperitoneal bleeding

Question 100

What is the treatment choice for Listeria?

Answer 100

Ampicillin is the treatment choice for Listeria, which is not sensitive to cephalosporins. Listeria most commonly causes disease in those with deficient cell-mediated immunity, such as young infants or immunocompromised patients.