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UWorld FACTOIDs > Key Associations 4 > Flashcards

Key Associations 4 Flashcards

1
Q

Pathogenesis of Fragile X

A

FMR1 located on long arme of X chromosome. Increased number of CGG repeats leads to HYPERMETHYLATION of cytosine bases and gene inactivation.

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1
Q

Artery that provides the majority of blood supply to the femoral head and neck

A

MEDIAL FEMORAL CIRCUMFLEX - injury can cause avascular necrosis of femoral head. Damage most common in DISPLACED fractures

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2
Q

Why does elastin have plasticity

A

DESMOSINE crosslinking between 4 different LYSINE residues on 4 different elastin chains, crosslinking via extracellular LYSYL HYDROXYLASE (elastin doesn’t form triple helixes)

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3
Q

Hirsutism

A

terminal hair growth in a male-like pattern

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4
Q

Virilization

A

hirsutism in association with clitoromegaly, increased muscle mass, acne, increased libido, voice deepening

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5
Q

Cause of idiopathic hirsutism in a female and Rx?

A

Due to increased conversion of testosterone into DHT via 5 alpha reductase or higher sensitivity of hair follicles to DHT. DOC is SPIRONOLACTONE due to anti-androgenic properties - blocks androgen receptors at hair follicles decreasing T production

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6
Q

in LV failure, fluid accumulation in the lung interstitum causes

A

DECREASED COMPLIANCE (reduced ability of lung to stretch during inhalation)

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7
Q

Causes of reduced compliance

A

Pulmonary fibrosis, insufficient sufactant, pulmonary edema

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8
Q

Profound cerebral hypoperfusion may lead to

A

GLOBAL CEREBRAL ISCHEMIA (ischemic-hypoxic encephalopathy) Watershed infarcts occur between zones of perfusion of anterior, middle, and posterior cerebral arteries causing bilateral wedge-shaped bands of necrosis.

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9
Q

Most vulnerable areas of brain to ischemia (affected first)

A

Pyramidal cells of hippocampus (Sommer’s sector CA1) and purkinje fibers of cerebellum

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10
Q

Retinopathy of prematurity

A

caused by use of concentrated oxygen for therapy. Upon return to normal room air, induces upregulation of VEGF causing neovascularization and possible retinal detachement

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11
Q

What is N-myc

A

a TRANSCRIPTION FACTOR can bind DNA (detected by DNA probes) C-myc overexpressed in Burkitt lymphoma

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12
Q

what is k-RAS

A

G-protein, mutations common in pancreatic malignancies

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13
Q

RET proto-oncogene

A

codes for membrane-bound tyrosine kinase receptor involved in celly cycle regulation, 95% mutated in medullary carcinoma

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14
Q

RAS gene

A

MAP kinase controls cell proliferation, found in FOLLICULAR Thyroid cancers

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15
Q

Pressure at the carotid bodie increases, the number of impulses

A

impulses sent to CNS increase, leading to parasympatheic stimulation

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16
Q

What conditions predispose to (a disease where valvular vegitations are found at autopsy)

A

VALVULAR INFLAMMATION, DAMAGE, AND SCARRING predispose to INFECTIVE ENDOCARDITIS

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17
Q

Type of receptor found on vascular smooth muscle

A

Beta 2

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18
Q

PPV in words

A

test’s ability to correctly ID those with disease from all those who had positive results (fraction of those with disease/positive results)

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19
Q

Sensitivity

A

Ability of test to RULE OUT those with disease

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20
Q

Specificity

A

represents ability of a test to EXCLUDE those without disease (low false positive)

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21
Q

Effect of PPV and FN if you lower the cut off point in a test?

A

Increases the sensitivity, true positives, but because FP will increase, the PPV and FN will increase

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22
Q

RANK receptor essential for

A

Differential of osteoclasts, hypoestrogenic states over-express this receptor increasing osteoclast activity

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23
Q

Not a gut derivative but receives blood supply from foregut

A

SPLEEN is mesodermal dorsal mesentary but receives branch off celiac from foregut

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24
Q

Gland found in dermus and subcutaneous fat of breat areolae, axillae, geintal regions

A

APOCRINE glands - secrete membrane bound vesicles (“sweat”) into hair follicles rather than directly to skin

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25
Q

Holocrine glands

A

sebaceous glands, discharge of entire secretory cell

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26
Q

Eccrine glands

A

also called merocrine glands - present in skin throughout most of body, watery fluid rich in sodium and chloride - SWEAT

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27
Q

merocrine glands

A

ECCRINE ! Same thing! Regular sweat glands

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28
Q

Presentation of PH, and may lead to:

A

DOE can progress to cor pulmonale with RV hypertrophy, may lea to SCD

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29
Q

Causes of lactic acidosis

A

Enhanced metabolic rate (Seizures, exercise) Reduced O2 delivery, Diminished lactate catabolism (hepatic failure), decreased oxygen utilization,

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30
Q

Predisposing factors for aspiration pneumonia

A

Impaired cough reflex/glottic slosure (dementia, drug intox) DYSPHAGIA due to neurologic deficit (stroke), GERD, nasogastric/endotrach tubes, vomiting, feeding tubes

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31
Q

MOA of the exotoxin produced by C. diptheriae

A

INHIBITS PROTEIN SYNTHESIS: AB toxin - the A (active) subunit of this exotoxin transfers a ribose residue from NAD to histidine on elongation factor -2 (EF-2) inhibiting protein synthesis (Unlike shigellas/EHEC’s toxin that inactivates 60S subunit)

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32
Q

MOA of toxin produced by B. Pertussis

A

INHIBITS PHAGOCYTIC ABILITY: stimulates intracellular G-proteins to increase cAMP production, leading to increased insulin production, lymphocyte and neutrophil DYSFUNCTION, and increased sensitivity to histamine

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33
Q

Function of EF-2 protein in eukaryotes

A

essential for PEPTIDE CHAIN TRANSLOCATION on the ribosome for protein synthesis

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34
Q

MOA of Shigella’s shiga toxin and EHEC

A

Inactivation of 60S ribosomal subunit

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35
Q

2 most common causes of focal brain lesios in HIV-positive patients

A

Toxoplasmosis and PRIMARY CENTRAL NERVOUS SYSTEN (CNS) LYMPHOMA -(of B-LYMPHOCYTE origin)

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36
Q

Primary CNS lymphoma

A

composed of B-LYMPHOCYTES and most commonly occurs in immunocompromised patients (AIDS) (most lymphomas are B)

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37
Q

Neuraminidase

A

required for the release of vius from infected cell and spread within respiratory tract (Oseltamivir inhibits)

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38
Q

Antithrombin inhibits

A

Factor Xa and THROMBIN

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39
Q

Neurophysins

A

proteins involved in posttranslational processing of oxytocin and vasopressin. Produced in neuronal cell bodies of PARAVENTRICULAR and SUPRAOPTIC nuclei and released into circulation from axon terminals in PP gland.

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40
Q

Recovery phase of ATN

A

POLYURIC phase, patients become dehydrated and can develop severe HYPOKALEMIA due to hgih volume, hypotonic urine

41
Q

Papillary necrosis is common in these patients

A

SCA, DM, analgesic nephropathy, severe acute pyelonephritis

42
Q

Function of Retinoblastoma (Rb) protein

A

Regulator of the G1 to S phase transition. (Cell stimulated by growth factor -> Activate Cyclin D and E, CDK4 and 6 then hyperphosphorylate Rb (inactive) -> Rb releases E2F transcription factor allowing cells to progress through G1 to S.

43
Q

Hypophosphorylated Rb protein

A

ACTIVE (the “brake”) - binds to E2F transcription factor. This complex INHIBITS transctiption of genes necessary for G1 to S transition.

44
Q

p27

A

cell cycle INHIBITOR acting on G1 (normal cells have high levels, cancer cells low)

45
Q

3 cytokines that mediate systemic inflammatory responses

A

TNF-alpha, IL-1 and IL-6 -> stimulate hepatic production of acute phase reactants (fibrinogen, ferritin, C-reactive protein, serum amyloid A, complement factors) -> cause RBCs to form stacks that sediment at a faster rate than normal individual erythrocyt

46
Q

ESR

A

non-specific marker of inflammation - acute-phase protein fibrinogen causes erythrocytes to form stacks (rouleaux) that sediment faster.

47
Q

Defense mechanism of a woman with 3 DUIs kills a child in a drunk driving accident, then spends her time lecturing about safe driving.

A

ALTRUISM - mature defense mechanism, alleviates guilty feelings through selfless service or giving to others.

48
Q

Reaction formation

A

replacement of an unpleasant or unacceptable thought or desire with its opposite.

49
Q

Transtentorial herniation compresses 4 structures

A

IPSILATERAL CN III, IPSILATERAL PCA, CONTRALATERAL CEREBRAL PEDUNCLE against tentorium, BRAINSTEM HEMORRHAGES (pons and midbrain, stretch and rupture of basilar artery -> fatal)

50
Q

What causes the majority of cases in Turner syndrome?

A

Karyotype 45, XO (complete monosomy M/C 50-60%) mitotic error in early development, 45XO/46XX (mosaicism), 46XX (with partial deletion of one X chromosome)

51
Q

Riboflavin

A

B2 precursor of coenzymes FMN and FAD. FAD is coenzyme in TCA for succinate dehydrogenase (Succinate to fumarate)

52
Q

2 variants of gastric adenocarcinoma

A

Intestinal - solid mass projecting into stomach glandular-forming cuboidal or colunar cells. DIFFUSE carcinoma - infiltrates stomach walls with signet-ring pattern

53
Q

MDR1 gene

A

human multidrug resistance gene codes for P-GLYCOPROTEIN, a TRANSMEMBRANE ATP-dependent EFFLUX pump protein with broad specificty for hydrophobic compounds. Increases efflux of chemotherapeutic agents from cytosol to allow tumor to survive.

54
Q

Are naked negative sense RNA viruses infections

A

No, must be able to act directly as mRNA using host’s intracellular machinery for trnaslation. Naked viruses containing single-stranded positive-sense RNA can be infectious

55
Q

Name the positive sense RNA viruses

A

I went to a RETROvirus TOGAvirus party drank FLAVIvirus CORONAviurs and ate HEPEvirus (hEv) CALIcivirus PICOrnavirus (PERCH) Polio, Echo, Rhino, Coxackie, HAV

56
Q

Triggers for Candida vaginitis

A

ANTIBIOTIC USE is M/C (suppress normal bacterial flora), Contraceptive use, corticosteroid, DM, immunosuppression

57
Q

Mechanism in Burkitt lymphoma

A

Translocatinon of c-myc oncogene on long arm of 8 with Ig heavy chain on chromosome 14 produce a NUCLEAR PHOSPHOPROTEIN (c-Myc) that functions as TRANSCRIPTION ACTIVATOR

58
Q

Vassopresin injected in patient with DI. Which substance will have clearane reduced the most?

A

UREA - reabsorbed in MCD

59
Q

Mechanism type IV HST

A

Hapten taken by APC, goes to lymph node, clonal expansion of CD4+ TH1 and CD8+ T, CD8+T cell is first responder when hapten is seen for the second time

60
Q

Why does glucagon improve the condition of an obtunded person that is bradycardic

A

Activates G-protein coupled receptors in cardiac myocytes causing activation of ADENYLATE CYCLASE and increases cAMP - releases calcium from intracellular stores and inccreases SA node firing.

61
Q

Risk factors for adenocarcinoma of the esophageal

A

Barrett’s esophagus, GERD, obesity, Tobacco

62
Q

Risk factors for SCC of esophagus

A

Alcohol, Tobacco, N-nitroso containing foods

63
Q

MOA of eosinophils in host defense during parasitic infection

A

ADCC - antibody-dependent cellular cytotoxicity with enzymes form cytoplasmic granules. Free IgE binds to parasite, this complex then binds Fc receptor located on eosinophil cell surface -> releases MBP

64
Q

Protein outside nucleosome core that facilitates nucleosome packing into a more compact structure

A

Histone H1 by binding and linking DNA between adjacent nucleosomes

65
Q

Hypercholesterolemia vs. lipoprotein lipase deficiency

A

Defects in LDL receptor and cholesterol (LDL) is not cleared increasing risk for accelerated CAD. LL deficiency results in increased serum chylomicrons, can’t clear dietary LIPID LOADS, at risk for PANCREATITIS

66
Q

Most active form of thyroid hormone

A

T3, 4 times the activity of T4

67
Q

What is T4 converted to in peripheral tissues?

A

T3 and Reverse T3 (rT3), the inactive form of thyroid hormone. T3 can’t be converted to T4 or rT3

68
Q

Half lives of T4, T3 and rT3

A

7 days, 1 day, <1day

69
Q

How does T3 cause negative feedback

A

hypothalamic TRH-secreting neurons and thyrotroph cells of AP. Acts on paraventricular nucleus to decrease synthesis of TRH itself. Also cause decreased responsiveness to TRH.

70
Q

Type II deiodinase present in cells of the hypothalamus and pituitary

A

Regulatory T3 concentrations partially arise from the conversion of systemic T4 to intracellular T3 by this enzyme

71
Q

Ability to remove RNA primers during DNA replication

A

DNA polymerase I, the only bacterial DNA polymerase with 5’ to 3’ exonuclease activity

72
Q

forms the RNA primer

A

PRIMASE (DNA dependent RNA polymerase)

73
Q

Why are primers needed?

A

DNA polymerase cannot begin synthesis fo daughter strands without a free 3’-hydroxyl group

74
Q

2 functions of DNA polymerase I

A

5’ to 3’ exonuclease activity, exision-repair enzyme (only one that does this) used to excise RNA primers. DEGRADES the RNA PRIMER and FILLS in the GAP with DNA

75
Q

DNA polymerase I

A

Degrades the RNA primer (3’ hydroxyl group), fills in gaps in DNA (prokaryote only)

76
Q

DNA polymerase III

A

elongates leading strand (prokaryote only)

77
Q

5’ to 3’ exonuclease activity

A

DNA polymerase I

78
Q

Which activity is performed to remove an RNA primer

A

5’ to 3’ exonuclease activity by the fucking DNA polymerase I

79
Q

Name 3 duties of DNA polymerase I

A

5’ to 3’ exonuclase activity (remove primer and remove damaged DNA), 5’ to 3’ polymerase (fill in DNA gaps); and 3’ to 5’ exonuclase activity (proofreading)

80
Q

Why did god give 5’ to 3’ exonuclease activity to a certain DNA polymerase?

A

DNA polymerase I is blessed with 5’ to 3’ exonuclease activity so it may REMOVE the RNA primer (initiates DNA polymerization) and REMOVE damaged DNA

81
Q

M/C cause of SAH

A

Saccular (berry) aneurysm, ANTERIOR COMMUNICATING ARTERY, associated with ADPKD

82
Q

Class of virus for measles

A

Helical, enveloped RNA virus, Paramyxoviridae.

83
Q

Complications of measles

A

Acute encephalitis, primary measles pneumonia, secondary bacterial infections (pneumonia and acute otitis); SSE

84
Q

Matching is used in a case-control in order to control for

A

COUNFOUNDING VARIABLES

85
Q

Recognize stop codons and terminate protein synthesis

A

Rleasing factors

86
Q

Mechanism of kidney stones in Crohns

A

MALABSORPTION - inflamed terminal ileum -> loss of bile acids impairs fat absorption -> XS lipids in bowel bind to calcium ions and soaps excreted -> dietary FREE OXALATE not bound by calcium is reabsorbed

87
Q

Attributable risk

A

AR = Event rate(treatment) - Event rate (placebo)

88
Q

How does CHF affect arteriolar resistance?

A

Decreased CO triggers the renin-angiotensin-aldosterone activation and incased sympathetic output RAISE RESISTANCE (AFTERLOAD) and exacerbate heart failure by making it more difficult for the failing heart to pump blood to tissues.

89
Q

Wilson’s disease causes cystic degeneration of these structures in the brain.

A

PUTAMEN and BASAL GANGLIA. Putamen is located medial to the insula and lateral to the globus pallidus. ID CORONAL SECTIONS.

90
Q

Function of the Ryanodine receptor

A

Calcium allowed into the cell by voltage-dependent calcium channels stimulates the ryanodine receptors, which then allows the RELEASE of A still larger pool OF CALCIUM stored within the SARCOPLASMIC RETICULUM.

91
Q

What is responsible for the rapid decrease in cytoplasmic calcium levels that immediately precede relaxation?

A

the sarcolemmal Na+/Ca2+ transmembrane protein exchange mechanism, it does not require ATP and accepts 3 extracellular Na+ ions in exchange for one intracellular Ca2+ ion

92
Q

What is virtually necessary in order to have acute pyelonephritis?

A

ANATOMIC or FUNCTIONAL VESICOURETERAL REFULX - weakening of vesicoureteral junction facilitate reflux.

93
Q

M/C cardiac abnormality predisposing to native valve bacterial endocarditis (NVBE) in the 15 to 60 year old age group in the US?

A

MVP predisposes to infected vegetations on mitral leaflets. Rheumatic valvular disease is also a potential but less common precipitant of NVBE

94
Q

M/C cause of aortic rupture? M/C site?

A

MVAs, AORTIC ISTHMUS - connection between the ascending and descending aorta, distal to where the left subclavian artery branches off the aorta.

95
Q

What is an operon

A

DNA sequence that contains at least 2 regulatory sites, the promoter and the regulator (operator)

96
Q

Main mechanism of glucose inhibition of lac operon expression

A

DEPLETION OF cAMP. High cAMP levels activate a protein CAP (catabolite activator protein) which binds cAMP to form a cAMP-CAP complex binding upstream to the promotor region acting as a POSITIVE regulator of lac-operon.

97
Q

How does high glucose concentration prevent the lac operon from producing structural genes to metabolize lactose?

A

Glucose decreases adenylate cyclase activity -> low intracellular concentration of cAMP -> poor binding of CAP to CAP-DNA bidning domain

98
Q

Main amino acid responsible for transferring nitrogen to liver for disposal

A

ALANINE, amino groups are transferred to ALPHA-KETOGLUTARATE to form GLUTAMATE which is processed in liver to form urea.

99
Q

What reaction does G6PD do?

A

Converts Glucose 6-phosphate to 6-PHOSPHOGLUCONATE using NADP+ (creating NADPH + H+)

UWorld FACTOIDs (10 decks)

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