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Usmle > Block 15 > Flashcards

Block 15 Flashcards

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USMLE® Step 1 flashcards
1
Q

Use of vaginal tampones or nasal packing

A

Leads to toxic shock syndrome staphylococcal

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2
Q

Staphylococcal abscess formation mechanism

A

-makes coagulase and toxins, forms fibrin clot around self –> abscess.

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3
Q

Dextrans

A

Made by viridan streptococcus, they bind to fibrin-platelet aggregates on damaged heart valves

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4
Q

Anti DNAse B indicates

A

Recent s.pyogenes infection as well as ASO titer

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5
Q

Scarlet fever features

A
  1. Blanching skin
  2. sand-paper like body
  3. Strawberry tongue
  4. circumoral pallor
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6
Q

CAMP FACTOR IN S.AGALCTIEA

A

Enlarges the hemolysis formed by s.aureus

Stands for the authors of test not cAMP

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7
Q

Osteocytes remain connected to each other

A

Using gap junctions

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8
Q

Ion extracellulary and intracellulary

A

Extra cellular: Na+ and Cl- an Ca+2

Intracellular : K+

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9
Q

RNA interference-

A

An important mechanism by which short- non-coding RNA sequence induces posttranscriptional gene silencing.

  • silencing types are small interfering RNA and microRNA (siRNA,miRNA)
  • altered expression of even few miRNA gene can lead to cellular dysregulation and has been implicated in the development of many diseases including hematologic and solid malignacnies.
  • synthetic siRNA sequence can be introduced into cells to silence specific pathogenic genes. (Eg c-Myc oncogene) and are being explored as a possible theraputic agent.
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10
Q

Manifestation of SLE

A

Clinical:

  1. Constitutinal,fever, and fatigue
  2. Symmetric, migratory arthritis
  3. Malar rash, and photosensetivity
  4. Serositis (pleurisy, pericarditis and peritonitis )
  5. Thromboembolic events (vasculitis and antiphospholipid)
  6. Cognitive dysfunction and seziures .
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11
Q

Libman sacks endocarditis

A

Small wart-like fibrinous lesion and generalized thickening that can affect the heart valves of patients with SLE.
These are typically assymptomatic but may lead to valvular insuffeciency or embolism.

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12
Q

Hyper IgM syndrome

A 
Etiology: 
-deficient CD40 L 
-failure of antibody to class switch 
-Xlinked recessive
Clinical: 
-recurrent sinopulmonary and GI infection, infection with oppouronistic pathogens and failure to thrive
Lab
 Increased IGM, and decreased all ohter immunoglobulins, flow cytometry shows absent CD40L on CD4+
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13
Q

Absent Enteropeptidase activity in the proximal intestinal villi can mean

A

Trypsin low activity

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14
Q

Sarcoidodsis liver changes

A

Scattred granulomas in liver

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15
Q

Marker that reflects activity of osteoblast

A

Serum bone specific Alkaline phophate

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16
Q

Osteoclast activity is reflected by

A
  1. Tatrate resistant acid phophatase
  2. Urinary hydroxyproline
  3. Urinary deoxypyridinoline
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17
Q

Sleep apnea patients are at increased risk of developing

A

Pulmonary hypertension ,
Most patients though will develop systemic hypertension due to chronic symphathetic stimulation and elevated plasma NE levels.

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18
Q

Wide splitting of S2 that doesnt change with respiration

A

Atrial septal defect, with left to right shunt causes wide and fixed splitting (no change with respiration) of the second heart sound.
-pts may also have mid systolic ejection murmur resulting from increased flow across pulmonic vlave.

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19
Q

DVt can lead to stroke in

A

Patients with patent formane ovale or ASD, large pulmonary arteriovenous malformation or VSD.

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20
Q

Types of exocrine glands

A
  1. Merocrine: cells secrete via exocytosis (salivery glands, eccrine swet glands, apocrine sweat glands)
  2. Apocrine: cells secrete via membrane bound vesicles (mammary glands)
  3. Holocrine: cell lysis release entire content of cytoplasm and cell membrane (sabecous glands and meibomian glands)
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21
Q

Horseshoe kidney -

A
  • its due to limitation of ascending during embryogenesis - due to inferior messenteric artery localization
  • patients with horseshoe kidney are at increased risk of ureteropelvic junction obstruction, recurrent infection, urolithiasis and neoplasm (wilms tumor, RCC).
22
Q

Homonymous hemianiopia with macular sparin

A

PCA infarction

23
Q

Hexagonal shaped crystals

A

Cysteine stones, raise the suspicion of cystienuria

24
Q 
Cysteinuria 
Clinical
Diagnosis
Treatment
Pathology
A

AR, affects high affinity, sodium independent dibasic amino acid transporter found on the apical membrane of the intestinal and proximal renal tubular epithelial cells.

  • this prevents dibasic amino acids (cysteine) from bein reabsorbed by PCT —> cystine stones.
  • diagnosis :elevated urinary cysteine crystals, sodium-cyanide nitroprusside test
  • treatment: alkalization of urine (acetozolamide)
25
Q

Sodium cyanide nitruprusside test

A

Qualtitative screening test that detects the presence of urinary cystine.

26
Q

Rubella vaccine is

A

Live attenuated vaccine (M-M-R)

27
Q

Congeintal rubella syndrome

A
  • neonatal defects :
    1. oh the head (microcephaly, mental retardation)
    2. Eyes (cataracts )
    3. Ears (deafness)
    4. Heart (PDA, pulmonic stenosis)
28
Q

The most significant factor for shigella infection

A

Mucosal invasion.
They invade GI mucosa via the M cells that overlies peyers patches. After cell entry, shigella is able to lyse its containment vacuole and enter cytosolic compartment.

29
Q

Shigella features and symptoms

A
  • non lactose ferementing
  • Gram negative rod, non-motile
  • ferement glucose and produce gas, doesnt produce H2S(hydrogen sulfide- unlike salmonella)
  • fever, abdominal cramps, dysentery.
30
Q

Meiotic nondisjunction usually occur in (what phase)

A

-meiosis I

31
Q

Sudden decrease in preload (sudden onset HF) in AS patients associated with

A
  • atrial fibrilation
  • this condition can occur in up to 10% of patients with severe aortic stenosis.
  • patients with AS, needs the atrial systole because the concenteric LV hypertrophy reduces the LV compliance, thus they need every drop of blood, thus they are dependent on atrial systole.,
  • in AFIB, hypotension develops in those patients due to loss of atrial systole, thus decreased preload —> acute pulmonary edema.
  • treated with cardioversion
32
Q

Hereditary PAH (pulmonary artery hypertension)

A

PAH is defined as mean pulmonary arterial pressure is >25 at rest.
Hereditary PAH is most often due to an incativating mutation in BMPR2 which is transmitted in an AD with variable penetrance.
- patients have predisposition for dysfuctional and smooth muscles cell proliferation.
- a second insult is then thought to activate the disease process, which involves endothelin and decreased NO and prostacyclin levels. > pulmonary fibrosis thickining –> hypertension.

33
Q

Aortic regurgitation changes

A
  • regurgitant blood flow –> increase LVEDV –> inrease preload –> eccenteric hypertrophy.
  • the eccenteric hypertrophy increases SV and maintains CO as compensatory mechanism.
  • patients with Acute AR have small left ventricular cavity and cannot significantly increase forward stroke volume to accomodate for the regurgitant blood flow.
34
Q

Class III anti arrythmic drugs (amiodarone, sotalol, dofetilide)

A

Predominantely blocks potassium channels and inhibit the outward potassium currents during phase 3 of cardiac action potential thereby prolonging depolarization and total Action potential duration

35
Q

EBV effect on B cells

A

-EBV stimulates B cells to enter the cell cycle, proliferate contineously ( transformation or immortalization).
This is accomplished when EBV encoded oncogene activate proliferative and anti apoptotic signaling pathways within the infected B cell.

36
Q

Phenytoin adverse effect

A
  • gingival hyperplasia(due to increased PDGF –> proliferation of gingival cells and alveolar bone)
  • ataxia and nystagmus
  • coarsening of facial features and hirsutism
  • metabolism of folic acid (megaloblastic anemia)
  • fetal hydantoin syndrome
37
Q

First order kinetics drugs

A

Read zero kinetic

38
Q

Polymorphism in CP450

A

May occur in the gene coding for these enzymes altering their expression or activity. Three important phenotype exist: poor, intermediate and rapid metabolizer.

39
Q

Pancreas divisum

A

When ventral and dorsal pancreatic buds fail to fuse.

  • the pancreatic secretion are instead drained via 2 separate duct systems.
  • the dominant dorsal duct of Santorini opens into the duodenum via minor papilla. And is responsible for draining the majority of the pancreas.
  • the smaller ventral duct opens into major papilla.
  • the pancreatic structure derived from the ventral pancreatic perimodium is the main pancreatic duct.
40
Q

CMV treatment

A

Ganciclovir, foscarnet, cidofovir .

41
Q

CMV induced retinitis
Present in
Comlication
Clinical

A
  • Histological = affected tissue would reveal full thickness retinal necrosis and edema, with eventual replacement by atrophic scar tissue.
  • its the most common cause of retinitis HIV positive patients is CMV, which is thought to develop secondary hematogenous spread of CMV to the eye.
  • CMV retinitis most frequently affects AIDS with CD4+ <50 cells/
  • most common complication is retinal detachment due to tearing of thin, atrophic scar tissue that forms in areas of prior inflammation.
42
Q 
Charcot Bouchard aneurysm 
Associated condition
Location
Size
Result of rupture 
Symptoms of rupture
A

Associated condition : hypertension
Location: basal ganglia, cerbelleum, thalamus, pons
Size <1mm
Result of rupture : intracereberal hemorrhage
Symptoms: progressive neurologic deficits, headache may follow.

43
Q

Bleeding head CT

A

Acute bleeding appears as hyperattenuated or bright lesion on noncontrast head CT.

44
Q

Colorectal cracinoma in IBD

A
  • its the most common type of malignancy in pts suffering from IBD.
  • colitis associated carcinoma is more likely to
    1. Affect younger patients
    2. Progress from flat and non polypoid dysplasia
    3. Histologically appear mucinous and/or have signet ring morphology
    4. Develops early p53 mutation and late APC gene mutation, opposite that of sporadic disease.
    5. Be distributed within the proximal colon (especially crohns disease) or concurrent primary sclerosing cholangitis)
    6. Multifocal in nature.
45
Q

Patient with asymptomatic carotid artery stenosis, given fibrinolysis

A

The condition can lead to intracereberal bleeding with signs of : coma, irregular breathing pattern and asymmetric pupils.

46
Q

Kaposi sarcoma colonic manifestation

A
  • colonoscopy: reddish/violet, flat maculopapular lesions or hemorrhagic nodules.
  • Microscopy: spindle shaped tumor cells with small vessel proliferation.
  • can lead to intermittent bloody diarrhea and abdominal pain in HIV patients .
47
Q

acute compartment syndrome

A

The most common site of ACS is the anterior compartment of the leg which include the foot extensor muscles , anterior tibial artery and deep peroneal (fibular ) nerve.
- injury can lead to loss of sensation between first and second toes, decreased dorseflexion, foot drop and claw foot.

48
Q

DNA shape in eukaryotic

A

-linear DNA (unlike prokaryotic), with multiple origins of replication ( this feature allows the eukaryotic genome to be copied quickly despite the large size)

49
Q

Acanthosis nigricans can be present in

A
  1. DM II

2. Adenocarcinoma usually gastric

50
Q

C.neoformans is treated with

A

Amphotericin B and flucytosine

Long term fluconazole

51
Q

Alternative splicing

A

Is a process by which different combinations of DNA regions (exons) are selectively included or exlcuded from mature mRNA transcript.

  • splicing is a post transcriptional modification that removes non-coding DNA regions (introns) from precursor mRNA.
  • the process is driven by large protein complex (spliceosome) comprimised of snRNPs.
  • alternative splicing can lead to formation of either mRNa with exon 1 +3 +5 / or any other combination (eg 1+2+3) .

Usmle (45 decks)

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