uWorld 16 Flashcards
when is a mutation in copper-zinc superoxide dismutase (SOD1) seen
ALS
what is the MOA of Riluzole
decreases glutamate release (reducing glutamate toxicity)
what cases genetic/antigenic shift in influenza A
REASSORTMENT of genomic segments of the HUMAN strain with the genomic segments of the ANIMAL (particularly avian) strain
reassortment only happens in SEGMENTED genomes
what causes antigenic drift
point mutations in HA and neuraminidase genes that slightly alter the protein products
what is transformation (bacteria and virus)
bacteria: uptake of naked DNA by pro or eukaryote
virus: incorporation of viral DNA into the host cell chromosome
there are the telomeres of a chromosome
3’ END OF CHROMOSOME (TTAGGG repeats)
what activates RAS in the Ras-MAPK pathway
a growth factor ligand binding to a RECEPTOR TYROSINE KINASE located on the cell membrane (which autophosphorylates the receptor)
Ras-GTP is the active form and activates RAF, which activates MAP kinase kinase which activates MAP kinase, which actives gene transcription
Nef and Tat are viral HIV proteins that do what
Tat gene: role in viral replication Nef gene: decreases expression of MHC class 1 proteins on the surface of infected cells
postural skeletal muscles such as the soles and paraspinal muscles contain predominately what kind of muscle fibers
Type 1 slow twice, red muscle fibers that derive ATP primarily from oxidative (aerobic) metabolism- thus they have HIGH MYOGLOBIN (oxygen storage) and MITOCHONDRIAL (aerobic respiration) concentrations
Type 1 fibers perform actions requiring low-level sustained force
describe type II muscle fibers
specialized for generations rapid forceful pulses of movement
Type IIb- derive ATP energy through anaerobic glycogenolysis and subsequent glycolysis
Type IIa (“FAST TWICTCH”): fibers are intermediate b/w type I and type IIb fibers- generate ATP via aerobic metabolism
what is the issue in I-Cell disease
deficient phosphorylation of mannose residues on certain glycoproteins in the Golgi apparatus
defect in PROTEIN TARGETING to LYSOSOMES
PHOTOTRANSFERASE ENZYME catalyzes the phosphorylation of mannose residues on lysosome-bound proteins
what is odynophagia and what does it suggest in the presence of GERD
pain with swallowing
presence of odynophagia usually indicates the progression to EROSIVE ESOPHAGITIS and the formation of an ULCER
where is resistance maximal in the lungs
2nd to 5th generation airways, including the segmental bronchi
ECG showing ST elevation in leads I and aVL w/ elevated cardiac enzymes would likely show occlusion of what artery
LEFT CIRCUMFLEX ARTERY (supplies LATERAL aspect of LEFT ventricle)
I and aVL are LATERAL LIMB LEADS (so are V5-V6)
what ECG findings are indicative of proximal LAD occlusion, what about distal LAD
proximal LAD: V1-V4 (anterior chest) leads are involved
distal LAD: V3-V4 are involved (V1-V2 are spared)
the LAD supplies what part of the heart
anterior aspect of left ventricle and interventricular septum
what ECG findings would be expected if the left main coronary were occluded
anterolateral infarction
ST elevation in the anterior (V1-V4) and lateral (V5-V6, I and aVL)
what ECG findings would be expected if the right coronary artery were occluded
supplies right ventricle and inferior aspect of the left ventricle
ST elevation in the inferior leads (II, III, and aVF)
what is the difference b/w absolute and relative polycythemia (erythrocytosis)
absolute has an INCREASE in total RBC MASS
relative has a NORMAL RBC mass
what is the difference b/w primary vs secondary erythrocytosis
serum EPO is LOW in PRIMARY erythrocytosis
EPO is HIGH in SECONDARY
what causes secondary erythrocytosis
chronic hypoxia from: high altitudes, smoking, COPD
abnormal secretion from neoplastic or otherwise diseased tissues
what defines hypoxic secondary erythrocytosis
SaO2 less than 92%
PaO2 less than 65mmHg
what innervates the posterior part of the external auditory canal
VAGUS NERVE (via small auricular branch)
what is VASOVAGAL SYNCOPE
passing out after stimulation of the posterior external auditory canal by an otoscope examination
parasympathetic outflow via vagus nerve leads to decreased heart rate and blood pressure
how does biliary atresia present
baby healthy at birth, but the present with JAUNDICE within the FIRST 2 MONTHS of life, along with DARK URINE, and ACHOLIC (pale or clay-colored) STOOLS
firm hepatomegaly due to inflammation
ELEVATED DIRECT BILIRUBIN and GGT (consistent with cholestasis)
what is seen on liber biopsy of biliary atresia
intrahepatic bile duct PROLIFERATION
portal tract edema
fibrosis
urgent surgical intervention is required
what is Gilbert syndrome
problem with glucuronidatio not bile
usually asymptomatic except at times of STRESS (FASTING, ILLNESS) during which mild
indirect hyperbilirubinemia and jaundice
breast milk jaundice is what
indirect hyperbilirubinemia that peaks at age 2 weeks
enzyme is BETA-GLUCURONIDASE and it deconjugates bilirubin
leads to increased absorption and therefore, increased enterohepatic circulation of bilirubin
urine and stool appear unaffected
what is the order of enzymes involved in base excision repair
glycosylase (cleaves the altered base leaving an AP site), endonuclease (cleaves 5’ end), lyase (cleaves 3’ sugar phosphate), polymerase (fills single nucleotide gap), ligase (seals nick)
excessive consumption of what can promote the deamination of cytosine, adenine, and guanine to form uricil, hypoxanthine, and xanthene (respectively)
DIETARY NITRATES
what is base excision repair used to correct
single-base DNA defects induced spontaneously or by exogenous chemicals
what lab abnormalities are seen in SLE
anemia, leukopenia, thrombocytopenia
Positive ANA, and ANTI-dsDNA, anti-Sm (snRNP)
LOW COMPLEMENT LEVELS (C3 and C4), increased IMMUNE COMPLEXES
what constellation of features is typical of new-onset SLE
“butterfly” rash
inflammatory arthritis
ULCER of hard palate
how does isoniazid resistance occur
decrease in bacterial expression of the catalase-peroxidase enzyme that is required for INH activation
modification of the protein target binding site for INH
if the left temporal hemiretina is fucked what geniculate nucleus is fucked and what other structures are affected
LEFT the temporal hemiRETINA stays on the side of origin
left lateral optic chiasm, optic tract, LGN body, optic radiations, and primary visual cortex
HPV has a predilection for what cells and where are these found in the respiratory tract
STRATIFIED SQUAMOUS EPITHELIUM found in anal canal, vagina, and cervix
TRUE VOCAL CORDS are the only area in the resp tract with this
what is seen on LM of actinic keratosis
hyperkeratosis (hyperplasia of the stratum corneum)
parakeratosis (retention of nuclei in the stratum corneum)
atypical keratinocytes w/ pleomorphic nuclei and multiple mitosis
actinic keratosis transform into what
Squamous Cell Carcinoma
what is the most common skin cancer
basal cell carcinoma
arises on sun-exposed skin and has a very low tendency to mets
presents a pearly papule w. central depression or ulceration
histo: NESTS of BASALOID cells and peripheral PALISADING of nuclei
what is a dermatofibroma
superficial benign fibrous hitiocytoma
result from the benign proliferation of fibroblasts
commonly arise ont eh lower extremities as a solitary nodule
psoriasis presents how
hyperkeratosis plaques that affect the scalp, knees, and elbows
characterized by CLUBBED RETE RIDGES, HYPERKERATOSIS, NEUTROPHILS in the status CORNUM, perivascular lymphocytic infiltrates
the parietal pleura generally extends how far blow the visceral pleura
2 ribs
what are the boarders of the visceral pleura
6th rib along midclavivular line (so parietal goes to 8)
8th along midaxillary (so parietal goes to 10)
10th along the paravertebral line (so parietal goes to 12)
parvovirus B19 infects what cells
erythrocytes precursors in the bone marrow
how can organisms develop resistance to aminoglycosides
amino glycoside-modifying enzymes (acetyl, adenyl, or phosphate groups are added to the amino glycoside antibiotic outside the bacterium)
mutated ribosomal subunit protein
mutated porin protein
if an enterococcus gets resistance to a drug by producing an enzyme that is involved in ACETYL group transfer to exogenous substances and is located on the surface of the cytoplasmic membrane what drug is it resistant to
an AMINOGLYCOSIDE (gentamicin) this is an AMINOGLYCOSIDE-MODIFYING ENZYME
how do quinolone get resistance
mutated DNA Gyrase or topoisomerase
impaired influx/increased efflux
how do enterocci get resistance to penicillin
mutated PBP
beta-lactamase production
how doe tetracyclines get resistance
impaired influx/ increased efflux
inactivated enzyme
why is Hep C so chronic
RNA-dependent RNA pol has NO PROOFREASDING 3’ to 5’ exonuclease activity, which results in many errors
hyper variable genomic regions- like those for envelope glycoprotein
what immunohistochemical stains are used of endothelium
CD34 and von Willebrand’s factor
among others
what are the initial symptoms of Picks Disease (frontotemporal dementia)
personality and behavioral changes (apathy, socially inappropriate behavior)
seen in early 50s or 60s
AD inheritance in 20-40% of cases
damage to the hippocampus results in what
inability to form new memories (anterograde amnesia)
one of first regions to suffer damage in Alzheimer’s
what is Gerstmann Syndrome
Damage to the inferior parietal lobe of the dominant hemisphere: right/left confusion dysgraphia dyscalculia finger agnosia
damage of sub thalamic nuclei causes what
contralateral hemiballismus
99m Tc-pertechtonate has an affinity for what and is used for what
parietal cells (including ectopic sites) used for Meckel Diverticulum
failure of proper descent during development of the hindgut can lead to what
imperforate anus
what are lentigines
seen in lentigo
small tan or brown macule most often seen on the sun-exposed skin of a middle-aged or elderly person
what drug do you use in someone with MRSA who is allergic to vanc
Daptomycin- depolarizes cellular membrane by creating transmembrane channels
ADRS: myopathy and CPK elevation
KEY: INACTIVATED BY SURFACTANT
what is the MOA and ARDs of linezolid
MOA: inhibits 23S ribosomal RNA of the 50S
ADRs: optic neuritis, thromboyopenia, increased risk of serotonin syndrome
