Uworld9 Flashcards
Lung abscess usually occurs in individuals with?
Episodes of impaired consciousness (eg, alcohol/substance use disorder, dementia) or decreased ability to swallow (eg, esophageal strictures).
They are generally caused by aspiration of anaerobic and aerobic bacteria from the oral cavity into the lower respiratory tract.
Thiazide diuretics function
Thiazide diuretics decrease intravascular fluid volume, which stimulates aldosterone secretion and leads to increased excretion of potassium and hydrogen ions in the urine.
This results in hypokalemia and metabolic alkalosis
Where is the majority of water reabsorption in the nephron?
In the proximal tubule passively with the reabsorption of solutes
What is nuclear factor kappa B (NF-kB)?
Is a transcription factor with a critical role in the immune response to infection.
Normally present in the cytoplasm in a latent, inactive state bound to its inhibitor protein, IkB.
Extracellular substances such as lipopolysaccaride can initiate a signal cascade that results in the destruction of IkB and translocation of free NF-kB to the nucleus
What is postpartum thyroiditis?
Occurs within 12 months of pregnancy and is characterized by autoimmune destruction of thyroid follicles.
It typically has a hyperthyroid phase due to release of preformed thyroid hormone, followed by a hypothyroid phase due to depletion of thyroid hormones stores and eventual return to a euthyroid state.
Thyroid metabolic activity during the hyperthyroid phase is suppressed, and glandular blood flow and radioiodine uptake are low.
The risk of progression of diabetic nephropathy in patients with proteinuria can be reduced by?
Appropriate glycemic and blood pressure control.
ACE inhibitors and angiotensin II receptor blockers are the preferred antihypertensive agents due to their antiproteinuric effects, which are independent from their effects on systemic blood pressure
Rheumatoid arthritis can cause joint destruction where?
RA causes progressive joint destruction involving the hands, wrists, elbows, and knees.
Cervical spine involvement can lead to spinal instability and cord compression.
What is seen in spherocytosis?
In spherocytosis, mean corpuscular hemoglobin concentration (MCHC) is increased due to mild dehydration of the RBC.
Markers of hemolysis are often evident and include elevated lactate dehydrogenase, reticulocytosis, and decreased haptoglobin
What is seen in malignant hyperthermia?
In patients with malignant hyperthermia, exposure to certain anesthetic agents (eg, succinylcholine, inhalational gasses) causes unregulated passage of calcium from the sarcoplasmic reticulum into the intracellular space.
This results in sustained muscle contraction that leads to hypercarbia, hyperthermia, and acidosis.
What is seen in schistosomiasis?
schistosomiasis, a parasitic blood fluke infection, is common in rural portions of sub-Saharan Africa.
Initial infection is often asymptomatic, but some patients develop chronic hepatosplenic (eg, portal hypertension, hepatosplenomegaly, esophageal varices) or urinary (eg, bladder cancer) complications years or decades later.
The presence of eosinophilia is an important diagnostic clue
What is the most important immune cell in the defense against invasive Candida infection?
Neutrophils.
Patients with neutropenia (eg, following cytotoxic chemotherapy) are at high risk for invasive disease (eg, candidemia, meningitis)
T lymphocytes are more important for prevention of superficial, mucocutaneous infection (eg, thrush)
MOA of nystatin
Polyene antifungal, acts by binding to ergosterol in the fungal cell membrane, causing the formation of pores and leakage of fungal cell contents.
Drug of choice for oropharyngeal candidiasis.
Not absorbed from the GI tract and is administered as an oral “swish and swallow” agent.
Cancer immunotherapy often includes the adminstration of monoclonal antibodies against a target overexpressed on the cancer cell surface. The Fc portion of the bound antibody is identified by?
natural killer cells via CD16, leading to antibody-dependent cellular cytotoxicity via the release of granzymes and perforin.
What is a koilocyte?
An atypical squamous cell characterized by perinuclear cytoplasmic clearing (ie, halo) and a large, dark nucleus with irregular contours (ie, raisinoid appearance)
These cytologic features are a viral cytopathic effect of human papillomavirus (HPV) infection.
2,3-bisphosphoglycerate (2,3-BPG) normally forms ionic bonds with the beta subunits of deoxygenated hemoglobin A, facilitating oxygen release in the peripheral tissues. Mutations that result in the loss of 2,3-BPG binding pocket’s positive charge cause hemoglobin A to resemble?
fetal hemoglobin, which binds oxygen with a higher affinity die to its inability to interact with 2,3-BPG.
What is seen in X-linked recessive inheritance?
- affected males will always produce unaffected sons and carrier daughters
- carrier females have a 50% chance of producing affected sons and carrier daughters
What inheritance pattern is G6PD def?
G6PD def is X-linked recessive and causes acute hemolytic anemia in response to oxidant drugs.
Patients with beta-thalassemia trait have 1 normal beta-globin allele and 1 mutated beta-globin allele. The gene mutation most commonly impairs?
mRNA processing (eg, splicing) or translation, resulting in reduced production of normal beta-globin chains.
Patients are typically asymptomatic with lab findings of mild microcytic anemia, target cells, and increased hemoglobin A2 concentration.
MOA of azathioprine
An immunosuppression drug that inhibits purine nucleotide synthesis and incorporates false purine nucleotides into DNA and RNA.
These effects reduce the proliferation and activity of both B and T lymphocytes
What is Chediak-Higashi syndrome?
AR disorder; affecting lysosomal trafficking that results in immunodeficiency, albinism, neurologic abnormalities (eg, nystagmus).
Giant granules are seen within neutrophils.
Role of von Willebrand factor
enhances clotting through both augmentation of platelet binding and stabilization of factor VIII
What can help with bleeding in patients with von Willebrand disease?
Patients with von Willebrand disease are deficient in functional vWF and present with increased bruisability and prolonged mucosal bleeding.
Desmopressin can alleviate bleeding through endothelial release of vWF.
What is a Mallary-Weiss tear?
A tear in the gastric mucosa near the gastroesophageal junction. Typically results from repetitive forceful vomitting, which can cause metabolic alkalosis
What causes hot tub folliculitis?
Pseudomonas aeruginosa; G-, oxidase+, non lactose fermenting motile rods that produce green pigment
What can cause injury to the long thoracic nerve?
Dissection of the axillary lymph nodes.
This results in weakness of the serratus anterior muscle with winging of the scapula and impaired abduction of the shoulder past the horizontal position
How does Hep A present?
fever, jaudince, hepatomegaly, leukocytosis, and aminotransferase levels> 1000
It triggers a robust CD8+ lymphocytic response to clear infected hepatocytes. The resulting hepatocellular damage is self limited, with complete resolution within 2-3 months.
What is a lacunar infarct?
Small, ischemic infarcts involving the deep brain structures (eg, basal ganglia, pons) and subcortical white matter (eg, internal capsule, corona radiata).
They most often occur due to hypertension, which causes hardening/thickening of the vessel wall (hypertensive arteriolar sclerosis), predisposing patients with this condition to thrombotic vessel occlusion.
What is characteristic for acute pericarditis?
acute-onset, sharp, and pleuritic chest pain that decreases with leaning forward.
Fibrinous/serofibrinous pericarditis is the most common form and a pericardial friction rub is the most specific physical finding.
Viral pericarditis often precedes by an upper resp infection
What is used for chemoprophylaxis of meningococcal disease?
Rifampin.
Dorsal columns location and function
located in the posterior spinal cord and convey vibration, proprioception, and light touch sensation.
lower limbs= gracile fasciculus and located medial
upper limbs= cuneate and lateral
What is acute hemolytic transfusion reaction?
antibody-mediated (type II) hypersensitivity reaction caused by pre-existing anti-ABO antibodies that bind antigens on transfused donor erythrocyte s
Subsequent complement activation results in erythrocyte lysis, vasodilation, and symptoms of shock. Findings: fever, hypotension, chest and back pain, and hemoglobinuria
What is a common complication of subarachnoid hemorrhage?
Communicating hydrocephalus; presents with deteriorating mental status.
Typically results from blood-induced impairment of absorption of cerebrospinal fluid by the arachnoid granulations
What disease has a corkscrew shaped organism?
Syphillis; treponema pallidum
Treatment for syphillis
penicillin, which blocks the last step in bacterial cell wall synthesis (transpeptidation)
What is the virulence factor of typhoidal strains of Salmonella?
Capsular antigen Vi; inhibit neutrophil phagocytosis, neutrophil recruitment, and macrophage-mediated destruction.
Typhoidal salmonella undergoes extensive replication in macrophages and is able to spread through the lymphatic and reticuloendothelial system, leading to widespread systemic disease (typhoid fever)
Which drug is associated with a lower incidence of torsade de pointes?
Amiodarone causes lengthening of the cardiac action potential, which manifests as QT interval prolongation on ECG. QT prolongation with amiodarone is associated with a very low risk of torsades de pointes.
Ixodes tick transmits which diseases?
Babesiosis, Lyme, and Anaplasmosis
What is thryoxine-binding globin deficiency?
benign disorder characterized by low total thyroxine T4 and normal free T4 and TSH levels.
Patients are euthyroid and do no require txt.
What can be used in pulmonary arterial hypertension to lower pulmonary arterial pressure?
Endothelin receptor antagonists (bosentan, ambrisentan) lower pulmonary arterial pressure and improve dyspnea in pts with pulmonary arterial hypertension
Chronic granulomatous disease is due to?
defective NADPH oxidase and is diagnosed by dihydrorhodamine testing, which measures neutrophil respiratory burst.
When NADPH oxidase is stimulated, dihydrorhodamine is normally oxidized and fluoresces green; it remains colorless (no oxidation) in patients with CGD
