Uworld32 Flashcards
Most cases of cleft lip and/or cleft palate are from?
Most cases of cleft lip and/or cleft palate have a multifactorial pathophysiology related to complex interactions between genetic and environmental factors.
What is tracheoesophageal fistula with esophageal atresia?
typically presents in the immediate newborn period with choking/coughing with feeding.
A feeding tube cannot be passed into the stomach; curling of the distal end of the enteric tube in the proximal esophagus on x-ray is diagnostic.
What is seen on biopsy for subacute granulomatous (de Quervain) thyroiditis?
characterized by painful thyroid enlargement and usually follows a viral illness.
Biopsy shows a mixed inflammatory infiltrate with macrophages and multinucleated giant cells.
What is retinoblastoma?
Retinoblastoma is associated with inactivating mutations of the RB1 tumor suppressor gene, which normally restricts cells from passing the G1/S checkpoint until the cell is ready to divide.
Impaired function of the Rb protein allows unrestricted progression through the G1/S checkpoint, leading to uncontrolled cell division.
Tumor cells must develop adaptations to avoid destruction by the innate and adaptive immune response. A common adaptation is to?
overexpress programmed cell death 1 ligand (PD-L1), which converts effector T cells to exhausted T cells.
Other adaptations include down-regulating class I major histocompatibility complexes, blocking T cell costimulation, and increasing immunoinhibitory cytokine secretion.
What is an effect of St. John’s wort?
St John’s wort induced cytochrome P450 hepatic microsomal enzymes. As a result, a wide variety of drugs that are metabolized by these enzymes, such as warfarin, will have lower plasma concentrations and decreased efficacy.
Hereditary breast cancer is most commonly associated with mutations in?
BRCA1 and BRCA2. These tumor suppressor genes are involved in DNA repair, and their mutations increase the risk of developing breast and ovarian cancer.
The most important airway-protective movements during swallowing are?
the anterior/superior displacement of the larynx, the tilting of the epiglottis to block the airway, and vocal fold adduction.
A chin-tuck maneuver can be helpful in some patients with aspiration by stimulating the airway-protective movement of the larynx.
Large prolactin-secreting pituitary tumors can compress the optic chiasm, causing?
bitemporal hemianopsia. In addition, elevated prolactin levels suppress release of GnRH, leading to decreased LH secretion and subsequently impaired testosterone production in men.
What is odds ratio formula?
OR= odds of exposure in cases / odds of exposure in controls
OR = ad/bc
Labs for DIC
Disseminated intravascular coagulation commonly occurs in the setting of sepsis and is characterized by widespread activation of the coagulation cascade with formation of microthrombi.
Labs: prolonged PT/PTT, thrombocytopenia, low fibrinogen (ie, a consumptive coagulopathy) and patients usually have signs of bleeding (eg, oozing from venipuncture sites)
What is the earliest manifestations of diabetic nephropathy?
Moderately increased albuminuria (urine albumin 30-300 mg/day) is the earliest manifestation of diabetic nephropathy.
Screening for diabetic nephropathy is best achieved using an albumin-specific urine assay (regular dipstick urinalysis has low sensitivity).
What is confounding?
Confounding occurs when the exposure-disease relationship is muddled by the effect of an extraneous factor associated with both exposure and disease.
Confounding bias can result in the false association of an exposure with a disease.
Left-sided heart failure can cause secondary pulmonary hypertension via?
elevated left-sided diastolic filling pressures transmitting backward to the pulmonary veins, resulting in pulmonary venous congestion.
Over time, pulmonary arterial remodeling (medial hypertrophy and intimal thickening with fibrosis) can occur, but not to the extent that occurs in (primary) pulmonary arterial hypertension.
Pathogenesis of diphtheria exotoxin
inhibits host cell protein synthesis by catalyzing the ADP-ribosylation of host cell elongation factor-2
Physiologic age-related changes in the cardiopulmonary system can lead to reduced ability to cope with critical illness. These changes include?
reduced maximal heart rate and cardiac output due to decreased responsiveness to adrenergic stimuli, reduced retention of arterial blood volume due to decreased arterial compliance, and reduced respiratory strength and gas exchange efficiency.
What is aplastic anemia?
a form of bone marrow failure caused by direct toxic injury or cytotoxic T cell destruction of multipotent hematologic stem cells, which leads to pancytopenia.
Bone marrow examination will show profound hypocellularity, an abundance of fat cells, and small clusters of morphologically normal hematologic cells.
What is the most common manifestation of Francisella tularensis?
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.
What muscles are the major hip flexors?
The rectus femoris, iliopsoas, and sartorius are the major hip flexors.
Of these, only the rectus femoris and sartorius also affect knee movement. The sartorius flexes the knee while the rectus femoris extends the knee.
What is seen in a 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 serpinginous tracks due to the subcutaneous migration of hookworm larvae.
Coadministration of selective serotonin reuptake inhibitors and monoamine oxidase inhibitors can produce?
excessive synaptic serotonin levels secondary to decreased reuptake and decreased degradation of serotonin, potentially causing serotonin syndrome.
To avoid the risk, a 2 week washout period after discontinuing an MAO inhibitor and before initiating SSRI therapy is required to allow sufficient time for MAO regeneration.
The flow-volume loop for chronic obstructive pulmonary disease is characterized by?
increased residual volume and total lung capacity, as well as a “scooped-out” expiratory pattern due to reduced expiratory flow rates.
Both airway narrowing due to chronic bronchitis and decreased elasticity due to emphysematous destruction of interalveolar walls are responsible for the hyperinflation and airflow limitation.
Invasive vascular procedures can be complicated by atheroembolic disease, which may involve the kidneys, GI tract, CNS, and the skin. Light microscopy shows?
a partially or completely obstructed arterial lumen with needle shaped cholesterol clefts within the atheromatous embolus.
Name the inhibitors and inducers of the P450
Rifampin, phenobarbital, and phenytoin are potent enhancers of the cytochrome P450 pathway; concurrent use of warfarin with these medications results in decreased efficacy of warfarin.
In contrast, cimetidine, amiodarone, and trimethoprim-sulfamethoxazole inhibit warfarin metabolism, increasing the risk of bleeding.
Difference between ACE inhibitors and angiotensin receptor blockers
Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers reduce the risk of chronic kidney disease in patients with hypertension and diabetes.
ACE inhibitors raise levels of bradykinin and can cause a nonproductive cough, an effect not seen with ARBs.
What is athlete’s heart?
Athlete’s heart refers to physiologic cardiac adaptations that improve cardiac function in response to high level endurance training.
There is predominant left ventricular eccentric hypertrophy with a small component of concentric hypertrophy, leading to an overall increase in LV mass, enlarged LV cavity size, slightly increased LV wall thickness and decreased resting heart rate.
What is alpha-1 antitrypsin deficiency?
Alpha-1 antitrypsin is the major serum inhibitor of neutrophil elastase.
Alpha-1 antitrypsin deficiency typically causes early-onset panacinar emphysema, predominantly affecting the lower lung lobes.
What is global cerebral ischemia?
typically precipitated by systemic hypotension (eg, cardiac arrest). The cells most susceptible to ischemia are the CA1 pyramidal neurons of the hippocampus.
Other areas of the brain that are damaged early in the course of global cerebral ischemia include the cerebellar Purkinje cells and the pyramidal neurons of the neocortex.
Muscles used when sitting up from the supine position include?
the external abdominal obliques, the recuts abdominis, and the hip flexors.
The iliopsoas muscle is the most important of the hip flexors and includes the psoas major, psoas minor, and iliacus.
The rectus femoris, sartorius, tensor fascia lata, and the medial compartment of the thigh also contribute to hip flexion.
Characteristics of an atrial septal defect
An atrial septal defect leads to increased right-sided blood flow due to left-to-right shunting.
Characteristics findings are an early-peaking midsystolic ejection murmur over the left upper sternal border (ie, pulmonic flow murmur) and wide and fixed splitting of S2.
The presence of rod-shaped intacytopalsmic inclusions (known as Auer rods) is characteristic of many forms of?
acute myeloid leukemia (AML).
The M3 variant of AML, acute promyelocytic leukemia, is associated with cytogenetic abnormality t(15;17) and typically shows abnormal promyelocytes with abundant cytoplasmic granules, multiple Auer rods, and bilobed nuclei.
Patients with intravascular volume depletion (eg, congestive heart failure, diarrhea, excessive diuresis) and chronic kidney disease depend on?
renal prostaglandin production to dilate the afferent glomerular arteriole and maintain the glomerular filtration rate.
Nonsteroidal anti-inflammatory drugs inhibit prostaglandin synthesis, which can cause prerenal azotemia in at-risk patients.
Anthracycline chemotherapeutic agents (eg, doxorubicin, daunorubicin) cause?
cardiotoxicity mainly through the formation of anthracycline-topoisomerase II DNA cleavage complexes that affect healthy cardiomyocytes. The cardiotoxicity is dependent on the cumulative dose of anthracycline received, and it manifests as dilated cardiomyopathy.
What is syringomyelia?
characterized by the formation of a cavity (syrinx) in the cervical region of the spinal cord. The syrinx damages the ventral white commissure, leading to bilateral loss of pain and temperature sensation that is limited to the affected levels (typically the arms and hands); distal sensation is preserved.
Destruction of the motor neurons in the ventral horns (due to extension of the syrinx) results in flaccid paralysis and atrophy of the intrinsic muscles of the hand.
What is opsoclonus-myoclonus associated with?
Opsoclonus-myoclonus is a paraneoplastic syndrome associated with neuroblastoma, the most common extracranial solid neoplasm in children.
The tumor typically arises from the neural crest cells of the adrenal medulla and presents with an abdominal mass and elevated catecholamine breakdown products.
MOA of carbonic anhydrase inhibitors (eg, acetazolamide)
reduce intraocular pressure in patients with glaucoma by reducing production of aqueous humor.
Carbonic anhydrase is also found in the renal proximal tubule, where it catalyzes reactions necessary for bicarbonate (HCO3) reabsorption. Acetazolamide therefore induces a mild diuresis with increased urine pH and resulting mild metabolic acidosis.
Homocystinuria is most commonly caused by?
a defect in cystathionine synthase, resulting in an inability to form cysteine from homocysteine.
Cysteine becomes essential in affected patients, and homocysteine buildup leads to elevated methionine.
Homocysteine is prothrombotic, resulting in premature thromboembolic events (eg, atherosclerosis, acute coronary syndrome) in these patients.
What is a side effect of vincristine therapy?
Neurotoxicity is the dose limiting adverse effect of vincristine therapy.
Vincristine inhibits axonal microtubule formation, resulting in impaired axonal transport and peripheral neuropathy (eg, numbness, tingling)
Pathogenesis of tuberculin skin testing?
Tuberculin skin testing triggers a type IV delayed-hypersensitity reaction in patients with previous infection due to the presence of primed, antigen specific CD4 T lymphocytes.
These lymphocytes recognize tuberculin proteins displayed on antigen-presenting cells (APCs) and become activated following a costimulatory interaction between CD28 on the T cell and CD80/86 on the APC.
What is seen on duodenal biopsy for celiac disease?
Celiac disease is caused by an immune-mediated reaction to gluten and classically leads to chronic gastrointestinal symptoms.
Diagnosis is confirmed by elevated tissue transglutaminase IgA antibody and duodenal biopsy showing villus flattening, intraepithelial lymphocyte infiltration, and crypt hyperplasia.
