Uworld 12

Front 1

Sweat glands in cystic fibrosis patients

Back 1

-patients with CF produce eccrine sweat that contains high concentrations of sodium and chloride compared to normal individuals

-in normal individuals CFTR protein serves as chloride channel that REGULATES FLOW OF SODIUM, CHLORIDE, and WATER across the epithelial membranes of the airways, biliary tree, intestines, vas deferens, sweat ducts, and pancreatic ducts

Front 2

Eccrine sweat

Back 2

-when first produced, eccrine sweat is isotonic with extracellular fluid

-as it travels through the eccrine duct to skin surface, chloride is resorbed via the CFTR, and sodium follows

-thus, the CFTR facilitates production of hypotonic sweat in healthy patients

-cystic fibrosis patients are unable to reabsorb chloride and sodium in the eccrine ducts, and therefore secrete high=sodium and high-chloride-containing sweat.

-this abnormality is the basis for the sweat chloride test, which is used to diagnose cystic fibrosis

-in CF patients, this can manifest as hypovolemic shock due to excessive sodium loss and intravascular volume contraction

Front 3

Annular pancreas

Back 3

-abnormal migration of the ventral pancreatic bud leads to formation of an annular pancreas

-an annular pancreas encircles the descending part of the duodenum, and may lead to symptoms of duodenal obstruction in neonates

-vs. incomplete fusion of ventral and dorsal pancreatic buds leads to pancreas divisor, an abnormality that is usually asymptomatic

-pancreas divisor may predispose to development of acute or recurrent pancreatitis, but it does not cause duodenal obstruction

-both the ventral and dorsal pancreatic buds are derivatives of the duodenal portion of the foregut.

Front 4

Capitation (payment method for doctors)

Back 4

-physicians paid fixed amount per enrollee, not per service

-physicians paid by capitation have incentives to contain costs due to fixed budget allocated to them

-if many enrollees seek care, or there are enrollees needing extensive care, physicians' costs can become greater than their income.

-thus physicians are motivated to provide more preventive care to catch illnesses early, so that patients stay healthier and need fewer test and procedures.

-vs. altered financial incentives with fee-for-service, discounted fee-for-service, and salary systems

Front 5

HPV types 16, 18, 31

Back 5

-Human papilloma virus (HPV) types 16, 18, and 31 are strongly associated with anal and cervical squamous cell carcinoma

-HIV infection increases prevalence of HPV infection and risk of anal carcinoma – this risk is further augmented in men who have sex with men

Front 6

Viruses in AIDS patients

-HSV-2

-CMV

-EBV

-Adenovirus

Back 6

-AIDS increases prevalence of herpes simplex virus type 2 (HSV-2) infection and frequency of symptomatic genital herpes recurrences

-HIV-positive patients with CD4 counts under 100/microliter are at very big risk of developing cytomegalovirus (CVM) infection, which most frequently causes RETINITIS in AIDS patients
--GI tract involvement can include esophageal ulcers and colitis

-HIV patients often experience reactivation of latent Epstein-Barr virus (EBV) infection – associated with non-Hodgkin lymphomas, and oral hairy leukoplakia
--clinically, oral hairy leukoplakia presents as white plaques on lateral tongue (vs. candidiasis – white buccal plaques)

-Adenovirus can cause severe upper respiratory illness, pneumonia, and disseminated infection in immunocompromised patients.

Front 7

Southern blotting

Back 7

-southern blotting is a technique used to identify DNA mutations

-southern blotting involves restriction endonuclease digestion of sample DNA, then gel electrophoresis and gene identification with a radioactively-labeled DNA probe (a single-stranded segment of radio labeled DNA complementary to the gene of interest).

Front 8

Type 1 collagen

Back 8

-type 1 collagen is found in dermis, bone, tendons, ligaments, dentin, cornea, blood vessels, scar tissue

-type 1 collagen is the most prevalent collagen in the human body and is the primary collagen in mature scars (e.g., on 1-year-old MI)

-deficiency of type 1 collagen can cause osteogenesis imperfecta

Front 9

Type 2 collagen

Back 9

-type 2 collagen is found in the cartilage, vitreous humor, and nucleus pulpous

-there is no common disease associated with type 2 collagen deficiency

Front 10

Type 3 collagen

Back 10

-type 3 collagen is found in skin, lungs, intestines, blood vessels, bone marrow, lymphatics, and granulation tissue

-granulation tissue is seen about 7 days after an acute myocardial infarction, but it is eventually replaced by type 1 collagen as the infarct matures (mature scar)

-Ehlers-Danlos syndrome (types 3 and 4) is associated with type 3 collagen deficiency

Front 11

Type 4 collagen

Back 11

-type 4 collagen is found in basement membranes

-Alport syndrome is associated with type 4 collagen deficiency

Front 12

Breast milk vitamin content

Back 12

-the breast milk content of vitamins D and K is typically insufficient to meet the nutritional needs of the newborn

-vitamin K is given parenterally to infants at birth to prevent hemorrhagic disease of the newborn

-exclusively breastfed infants may develop vitamin D deficiency if they are not adequately exposed to sunlight

--dark-skinned infants are at especially high risk for vitamin D deficiency because they must be exposed to sunlight for longer periods of time to generate adequate vitamin D.

Front 13

Jugular foramen syndrome

Back 13

-lesions to jugular foramen can result in jugular foramen syndrome, which is characterized by dysfunction of cranial nerves 9, 10 and 11.

Front 14

Anterior cranial fossa

Back 14

-CN 1 olfactory bundles traverse the cribiform plate of the anterior cranial fossa

Front 15

Middle cranial fossa

Back 15

-CN 2, opthalmic artery, and central retinal vein traverse optic canal

-CN 3, 4, V1, 6, opthalmic vein, and sympathetic fibers traverse superior orbital fissure

-CN V2 (maxillary) traverses foramen rotundum

-CNS V3 (mandibular) traverses foramen ovale

-Middle meningeal artery and vein traverse foramen spinosum

Front 16

Posterior cranial fossa

Back 16

-CN 7 and 8 traverse internal acoustic meatus

-CN 9, 10, 11, and jugular vein traverse jugular foramen

-CN 12 traverses hypoglossal canal

-Spinal foots of CN 9, brain stem, and vertebral arteries traverse foramen magnum

Front 17

Polycystic renal disease presents with complaints of bone pain

Back 17

-Chronic renal failure is a common cause of secondary hyper-parathyroidism

-typical laboratory abnormalities include high PTH, low calcium, high phosphate, and low calcitriol

-chronic renal disease leads to diminished urinary excretion of phosphate, with elevated serum phosphate levels

--serum phosphate forms complexes with serum calcium, decreasing level of calcium available to the tissues,

-loss of renal parenchyma also causes decreased renal calcitriol (activated vit D) production

--calcitriol deficiency leads to decreased calcium absorption and increased calcium loss in the urine

-net effect of these processes is low serum calcium and high serum phosphate concentrations.

-high phosphate and low calcium stimulate PTH secretion from parathyroid glands

Front 18

Leukocyte adhesion deficiency

-presentation: 1-year old caucasian male with recurrent indolent skin infections and gingivitis – also had delayed separation of umbilical cord (10 weeks after birth)

Back 18

-leukocyte adhesion deficiency results from autosomal recessive genetic absence of CD18

-this leads to inability to synthesize integrins

-integrins are necessary for leukocytes to exit bloodstream

–sequelae of this illness include recurrent skin infections WITHOUT pus formation, delayed detachment of umbilical cord, and poor wound healing

Front 19

Myeloperoxidase deficiency

Back 19

-myeloperoxidase deficiency is immune deficiency similar to that caused by chronic granulomatous disease (CGD)

-In CGD, absence of NADPH oxidase causes an inability to form hydrogen peroxide, and therefore the enzyme myeloperoxidase has no substrate (i.e., hydrogen peroxide) to metabolize into reactive oxygen species used to kill microorganisms.

-in CGD, some phagocytosed organisms can still be killled because they produce their own hydrogen peroxide, which myeloperoxidase then uses to make free radicals

-vs. myeloperoxidase deficiency: since myeloperoxidase enzyme is absent, both catalase positive and catalase-negative organisms survive within phagocytes

Front 20

Deficiency of late complement components (C5b – C9)

Back 20

-deficiency of late complement components results in inability to form membrane attack complex

--> predisposes to Neisseria infections

Front 21

Transcobalamin II

Back 21

-transcobalamin II is one of three transcobalamins that act as carrier proteins for vitamin B12 after it is absorbed in the ileum

-therefore, transcobalamin II deficiency could lead to B12 deficiency

Front 22

Alpha-2-globulins

Back 22

-alpha2-globulins are normal serum proteins made by liver and kidneys

-include haptoglobin, ceruloplasmin, and alpha2-macroglobulins

-haptoglobin acts as scavenger molecule for hemoglobin that is released from red blood cells during hemolysisi

-ceruloplasmin acts as a serum carrier protein for copper ions, and is decreased in Wilson's Disease