UWORLD facts 2 Flashcards
Enterococci are ______hemolytic, while GAS is ___ hemolytic
enterococci: gamma hemolytic (non-hemolytic)
GAS: beta-hemolytic
Which bacteria has a positive Quellung reaction?
Strep pneumo (swelling of bacterial capsule when exposed to antibodies)
What is the only coagulase positive Gram positive coccus?
S aureus
Which is catalase positive? Staph or Strep?
Staph is atalase positive
80% of patients with reactive arthritis are positive for HLA-B27. They develop rehumatic symptoms 2-6 weeks after GU infxn/diarrhea caused by which organisms?
chlamydia, campylobacter, salmonella, shigella, or Yersinia
Neutrophil recruitment resulting in the creation of small microabscesses at the dermal papillary tips, also known as dermatitis herpetiformia (on extensor surfaces), is associated with what intestinal pathology?
Celiac disease
Deficiency of adenosine deaminase causes what?
SCID (autosomal recessive)
Definciency of purine nucleoside phosphorylases (PNP) leads to what?
isolated T-lymphocyte defect
Deficiency of HGPRT results in Lesch Nyhan syndrome. What does it result in increased buildup of?
increased purine syntehsis (decreased purine salvage); hyperuricemia, hyperuricuria
Which antibiotics inhibit prokaryotic protein syntehsis at the 30s ribosomal subunit?
tetracyclines and aminoglycosides
How doe macrolide antibiotics work?
bind to the 50s prokaryotic ribosomal subunit and prevent tRNA release from donor site AFTER peptide bond formation (chloramphenicol binds at the same spot but prevents new peptide bond formation)
How does rifampin work?
blocks prokaryotic mRNA synthesis by bacterial RNA polymerase
How does diptheheria toxin work?
prohibits protein syntehsis in eukaryoticcells through ADP ribosylation of EF2
Trace progression of cell from zygote to dermal cell.
Zygote –> morula –> embryoblast –> epiblast –> mesoderm –> dermal cell
What are the direct cholinergic agonists (don’t require release of AcH to work)?
pilocarpine, bethanechol, carbachol
What are the indirect cholinergic agonists (require release of AcH, because they are acetycholinesterase inhibitors)?
physostigmine, neostigmine, edrophonium
In pernicious anemia, which hormone builds up?
Gastrin (usually inhibited by hydrochloric acid).
Levles of IF, gastric acid, and secretin are low.
What is flutamide?
androgen receptor antagonist on target cells
What abnormalities are seen in DiGeorge syndrome?
C: cardiac abnormalities (ToF, truncus arteriosus, interrupted aortic arch) A: abnormal facies T: thymic aplasia C: cleft palate H: hypocalcemia, hypoparathyroidism 22 (22q11.2 deletion)
What are the two steps for antibody isotype to switch?
1) activation of transcritpion at region in the Ig locus
2) CD40 on B cells, causing DNA switch recombination
defect of CD40 leads to low levels of IgA, IgG, and IgE form original IgM/IgD antibodies
How does DNA methylation affect the transcription of genes? Which repeat sequences are preferentially methylated?
DNA methylation = silences gene transcription
methylated regions are typically rich in cytosine-guanine dinucleotide repeat sequences
Macrophages that look like wrinkled tissue paper:
Hepatosplenomegaly, aseptic necrosis of femur, bone crises
Gaucher cells, seen in deficiency of glucocerebrosidase = Gaucher’s disease (most common lysosomal storage disease). Glucocerebroside builds up
Severe extremity pain, decreased ability to sweat, corneal and lenticular changes, GI dysfunction, angiokeratomas:
Fabry disease, X linked R (all other lysosomal storage diseases are AR), deficiency of a-galactosidase (increased ceramide triheoside)
Progressive neurodegeneration, cherry red spot on macula, foam cells, HEPATOSPLENOMEGALY:
Niemann-Pick disease; deficiency of sphingomyelinase (increased sphingomyelin)
Progressive neurodegeneration, developmental delay, cherry red spot on macula, lysosomes with onion skin, NO HEPATOSPLENOMEGALY
Tay-Sach’s disease; deficiency of hexosaminidase A, accumulation of GM2 ganglioside
What is the signaling pathway of a-1 adrenergic receptor?
Gq –> phospholipase C –> IP3 (liberates stored intracellular calcium) and DAG (actives protein kinase c)
gnrh, oxytocin, adh (vasopressin), trh, histamine, angiotensin II, gastrin
What is the signaling pathway used by beta-adrenergic receptors, glucagon, fsh, lh acth, tsh, crh, hcg, adh (v2 receptor), histamine, epinephrine?
Gs –> adenylate cyclase –> cAMP (activates protein kinase A for intracellular effects)
Cyclic GMP is the second messenger for which hormones?
atrial natriuetic peptide and NO
guanylate cyclase –> cGMP –> protein kinase G (intracellular effects)
______ is a monoclonal antibody to TNF-a, while _______ is a recombinant TNF receptor fusion protein
infliximab = monoclonal antibody
etanercept: recombinant receptor fusion protein
What is the mechanism of action of aspirin with regards to platelets?
Aspirin inhibits cox-1 in platelets, which inhibits formation of prostaglandin H2 and preventing the synthesis of thromboxane A2, a potent stimulator of platelet aggregation and vasoconstriction.
From where does the azygous vein draw blood?
from the posterior walls of the thorax and abdomen into the SVC
What is teh ductus venosus?
In the fetus, the ductus venosus drains blood from the gut/liver directlyi nto the IVC, bypassing the sinusoids.
What is bacterial transformation?
when bacteria take up naked DNA from the environment and incorporate it into their genomes
What is bacterial transduction?
Bacteriophage-mediated transfer of genetic information.
What is bacterial conjugation?
Conjugation is a process where DNA is passed from one bacterium to another by direct cell-cell interaction, as awith a sex pilus
Graunular deposits of IgG and/or C3 are seen in what renal disease?
membranoproliferative glomerulonephritis
Glomerular capillary wall thickenign with spiky subepithelial IgG deposits is seen in
membranous glomerulonephritis
linear deposits of IgG and often C3 is seen in
anti-GBM disease, a form of rapidly progressive glomerulonephritis
p53 is a tumor suppressor gene mutated in which syndrome?
Li Fraumeni
The darkest line on an electron micrograph represents:
the Z line = where thin filmaents, composed of actin/tropomyosin/troponin anchor
What is the I band?
The Z line and only the thin (actin) filaments that do not overlap with thick (myosin) filaments
What is the H band? What lies at the center?
the section of the sarcomere containing only thick (myosin) filametns that do not overlap with actin.
At the center is the M line, wher ethe myosin filaments anchor in the center of the sarcomere
What is the A band?
The A band is the only named band in teh sarcomere containing an overlap of thick and thin filaments
When the sarcomere contracts, which bands will narrow?
H, I
A band DOES NOT contract
What is the virulence factor of Aspergillus?
vascular invasion (infections can disseminate to distant organs by hematogenous spread)
A polysaccharide capsule is the virulence factor of
strep pneumo, h flu, neisseria meningitidis