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MLSCI 262 > Final Exam > Flashcards

Final Exam Flashcards

1
Q

Acute Coronary Syndrome

A

sudden cardiac disorder which is irreversible

varies from angina, unstable angina, myocardial infarction

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2
Q

Acute Myocardial Infarction

A

acute obstruction of blood circulation (ischemia) to a region of the heart muscle, resulting in myocardial injury and necrosis (>1 cm)

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3
Q

this results in shortage of oxygen required for cell metabolism

A

ischemia

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4
Q

most common cause of AMI

A

atherosclerosis

  • plaque develops in the wall of the artery
  • plaque builds up
  • plaque ruptures
  • clot forms around rupture = blocking blood flow =lack of O2 and nutrients to myocardium = cell death
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5
Q

Troponin T

A

binds to tropomyosin and thin filament anchor of troponin complex
- found in cardiac muscle and regenerating skeletal muscle

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6
Q

Troponin C

A

binds Ca2+ to produce conformational change in troponin I subunit
- found in cardiac and striated skeletal muscle

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7
Q

Troponin I

A

binds to actin ONLY in cardiac muscle

- key regulator of cardiac muscle contraction/relaxation

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8
Q

actin

A

involved in muscle contraction

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9
Q

tropomyosin

A

regulate actin function

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10
Q

_____ & ______ are considered cardiac-specific targets in diagnostic tests for cardiac muscle damage

A

only cTn I and cTn T

- troponin I and T

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11
Q

when myocardial cells die, this is releaed

A

cardiac troponin cTn

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12
Q

depending on the type of MI, cTn levels reach their maximum between…

A

6 hours and 3 days and then start to decline

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13
Q

symptoms of AMI in men

A
  • chest discomfort or pressure
  • central chest pain -> arms, neck and/or jaw
  • shortness of breath, coughing/wheezing
  • unexplained fatigue, anxiety
  • less common = light-headed/dizzy, nausea/vomiting, sweating
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14
Q

symptoms of AMI in women

A

more non-chest pain symptoms

  • mild discomfort in chest/achy or heavy feeling in the chest
  • upper body discomfort
  • feeling of bad indigestion, nausea
  • shortness of breath
  • extreme fatigue, sweating
  • light-headed/dizzy, fainting
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15
Q

roles of hs-cTn

A
  • allows more rapid diagnosis and treatment of AMI
  • potential use in assessing risk of CV events in the general population
  • population reference ranges may allow differential diagnosis of AMI in biological males and females
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16
Q

CK-MB and MB (myoglobin)

A
  • past cTnI and cTnT assays
  • CK-MB = measurable for the same or later time than troponin; less sensitive (smaller elevation) than troponin N w/ 48 hr; not specific to cardiac damage
  • MB = measurable for a much shorter period than troponin; less sensitive (much smaller elevation) than troponin; not specific to cardiac damage
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17
Q

symptoms of <3 failure

A
  • difficult breathing
  • dry, hacking cough
  • swollen ankles, legs, abdomen
  • rapid weight gain
  • dizziness, fatigue, weakness
  • decreased ability to exercise
  • rapid or irregular heart beat
  • increased need to urinate at night
  • stomach bloating
  • lack of appetite or nausea
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18
Q

what is <3 failure?

A
  • heart is weakened/damaged and cannot pump blood effectively during increased activity or stress
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19
Q

reduces blood pressure and cardiac output

A

BNP (brain natriuretic peptide)

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20
Q

left ventricle wall stress

A

release of Pro-BNP and its de novo synthesis

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21
Q

where is NT-proBNP cleaved to its active form?

A

in peripheral circulation

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22
Q

what does BNP do?

A

interacts with natriuretic peptide receptor A

  • natriuresis/diuresis
  • peripheral vasodilation
  • inhibition of RAAS
  • inhibition of sympathetic nervous system
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23
Q

blood BNP correlates with…

A

severity of congestive heart failure

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24
Q

BNP can be elevated in other conditions (besides CHF)

A
  • valvular heart disease
  • atrial fibrillation
  • myocarditis
  • acute coronary syndrome
  • cardiac surgery
  • congenital heart disease
  • advancing age
  • pulmonary hypertension
  • sleep apnea
  • critical illness
  • sepsis
  • burns
  • renal failure
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25
Q

factors affecting test results in a BNP & NT-proBNP immunoassay

A
  • heterophile Abs
  • biotin interference (supplements!)
  • ALP-related signal interference
  • patient’s comorbidities
  • administered meds
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26
Q

should we measure BNP or NT-proBNP

A
  • both have similar sensitivity and excellent specificity for CHF
  • both have excellent precision
  • values are BOT interchangeable (no conversion factor)
  • both tests affected by: kidney function, age, sex
  • in-vitro stability (NT-proBNP stable without additives in whole blood for 72 hrs); both stable during freeze/thaw process
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27
Q

multi-focal chronic vascular disease that underlies the cause of CV disorders

A

atherosclerosis

  • heart: coronary heart disease (heart attack)
  • brain: cerebrovascular disease (stroke)
  • periphery: peripheral vascular disease (amputation)
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28
Q

this is characterized by fibro-inflammatory lipid plaque in arteries (occurs only in arteries)

A

atherosclerosis

  • reduces blood vessel elasticity
  • reduces blood flow
  • can rupture, travel, and lodge in smaller blood vessels and block blood flow
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29
Q

major form of fat in nature

A

triglycerides

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30
Q

triglycerides

A
  • storage form of fatty acids
  • fatty acids used for E production & synthesis of phospholipids, cholesterols, esters, etc.
  • fatty acid structures = saturated vs. cis-unsaturated vs. trans-unsaturated
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31
Q

phospholipids

A

two fatty acid chains and a phosphorous-containing group are attached to the glycerol backbone

  • for cell signalling
  • structures = membranes, lipoproteins
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32
Q

cholesterol

A

interlocking hydrocarbon rings from a steroid

  • structures = membranes, lipoproteins
  • steroid precursor of = bile acids (solubilize for digestion)
  • steroid hormones (androgens, estrogens, progesterone, adrenocortical hormones)
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33
Q

core and coat of lipoproteins

A

coat: phospholipid, unesterified cholesterol, apoproteins
core: triglycerides and cholesterol esters

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34
Q

apoproteins

A
  • top of lipoprotein structure
  • activate enzymes involved in lipid metabolism
  • maintain structural integrity of lipid-protein complex
  • deliver lipids to cells upon recgonition by cell surface receptors
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35
Q

exogenous pathway of lipoprotein metabolism

A

CM; metrabolism of lipoproteins produced by intestine form dietary lipids

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36
Q

endogenous pathway of lipoproteins

A

VLDL, IDL, LDL

  • metabolism of lipoproteins produced by the liver
  • delivery of lipids to tissues forward lipid transport (FLT)
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37
Q

reverse cholesterol transport lipoprotein metabolism

A

HDL

- removal of free cholesterol from peripheral tissues

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38
Q

these protect against CHD

A

HDLs

  • remove cholesterol from periphery to liver
  • antioxidant properties, inhibit platelet activation
  • increase HDL by 1% decreases coronary risks by 2-3%
  • increase HDL with decrease LDL leads to stabilization of plaque and eventual regression
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39
Q

Xanthomas

A
  • deposition of lipid in skin, eyes

- common symptoms of hyperlidemias

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40
Q

Apoprotein measurements

A

immunoassay

  • turbidimetry, nephelometry
  • ELISA (apo-A, apo-B)
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41
Q

most accurate way to measure HDL

A

ultracentrifugation

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42
Q

chemical preparation for HDL cholesterol for ultracentrifugation

A
  • routine method

- use polyanion/divalent cation (heparin/Mg 2+)

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43
Q

measuring indirect LDL cholesterol

A
  • Friedwald formula
  • assumes all cholesterol is VLDL, LDL, and HDL
  • CM usually low in fasting subjects
  • IDL and VLDL usually insignificant cntributors to toal cholesterol
  • [LDL cholesterol] = [total chol] - [HDL chol] - TG/2.2

note: non-fasting speciman may have CM when TG> 4.0 mmol/L = ? presence of CM or CM remnants

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44
Q

direct LDL cholesterol

A
  • newer methods precipitat VLDL, IDL, and HDL with polyvalent Abs to apo-A & apo-E
    > LDL almost exclusively apo-B100
  • may be less accurate if TG is very high; small dense LDL are present
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45
Q

non-HDL cholesterol

A
  • new alternate target, like apo-B, to LDL-C in canadian lipid guidelines
  • sum of all cholesterol transported in atherogenic lipoproteins, regardless of [TG]
  • high predictive value of CV risk
  • non-HDL-C = [total chol] - [HDL chol]
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46
Q

high sensitivity C-reactive protein

A
  • acute phase reactant
  • positively correlated with risk of future CHD events
  • strong preictor of: IM, stroke, peripheral vascular disease, sudden cardiac death
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47
Q

Removes and breaks down triglycerides from chylomicrons

A

lipoprotein lipase

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48
Q

abetalipoprotenemia

A

no beta lipoprotein synthesis

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49
Q

hypoalphaproteinemia

A

defective apoA1 synthesis

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50
Q

hypoalphaproteinemia

A

defective apoA1 catabolism

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51
Q

medical diagnostic testing performed outside the cinical lab, in close proximity t where the patient is receiving care

A

point of care testing (POCT)

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52
Q

POCT has the potential to… (in hospital setting)

A
  1. speed up diagnosis and timely management
  2. reduce iatrognic anemia
  3. reduce short- and long-term complications
  4. reduce overall length of stay
  5. improve workflow and resource utilization
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53
Q

POCT has the potential to… (in community setting)

A
  1. speed up diagnosis and timely management
  2. increase compliance with treatment requirements
  3. promote healthier lifestyle choices
  4. improve long-term outcomes
  5. reduce the number of clinic visits
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54
Q

limitations of POCT

A
  • limited test menu
  • usually (but not always) the more expensive option or patient testing
  • often (but not always) results are less accurate
  • sometimes appears decetively simple
  • harder to enforce compliance with regulations
  • hidden costs
  • may require clinical workflow modifictions to be an effective solution
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55
Q

theoretical plates

A

effective number of times a chemical distributes between the mobile and stationary phas as it moves through the system

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56
Q

great way to imrove the separation of peaks in a sample

A

increasing column length

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57
Q

approaches to imrprove resolution

A
  1. increase column efficiency: reduce width at peak baseline
  2. increase column selectivity: increase peak separation
  3. increase degree of column retention by increasing tR using a mobile phase thast is a weaker solven for analyte of interest
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58
Q

void time (tM)

A

time to elute non-retained molecules

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59
Q

T or F. the carrier gas in gas chromatography does not interact with volatile samples

A

T!

low density inert gasL usually nitrogen, helium, argon, hydrogen

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60
Q

gas chromatography sample separation is based on

A

differences in vapour pressure and interactions with the stationary phase

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61
Q

gas chromatography retention time depends on

A
  • support SA
  • pore size (if using polymer kind of support)
  • functional groups
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62
Q

what is sample derivization?

A

for gas chromatography

- if samples are not sufficiently volatile or thermally unstable = often modify polar groups

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63
Q

what is headspace analysis?

A

analyze the vapour above the sample if they have non-volatile saple

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64
Q

what is headspace analysis?

A

analyze the vapour above the sample if they have non-volatile samples

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65
Q

sample derivization methods

A
  • replace active H with trimethylsilyl group (TMS)
  • alkylation by addition of a methyl ester
  • acylation to produce an acetate derivative
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66
Q

interactions in GC when they have similar polarity

A

interactions increase at the same temperature!

- polar sample and polar liquid = increase in tR

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67
Q

high temperatures in GC

A

short tR but poor separation

- temperature gradients giv the best separation (account for bp and polarity)

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68
Q

carrier gas flow rate for GC

A
  • high flow rate decreases interaction of components with stationary phase
    => reduces retention time
    => poor separation of sample components
  • optimal flow rate ensures reroducible tR
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69
Q

T or F. peak broadening is inversely proportional to flow rate

A

T! peaks broaden (molecule travelling in all directions; increase in tR) with decreased flow rate

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70
Q

what is gas-liquid chromatography column bleed?

A

liquid coating on support eventually leaves column!

=> noisy/high background signaldetected; decreased chemical retention

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71
Q

how to minimize column bleed?

A

minimize by using a bonded stationary phase instea (chemically-bonded to support)
-> bonded-phase GC

  • polysiloxane: amount and typ of sid-chains (R gorups) affedcting chemical tR
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72
Q

before use, any column or GC must be …

A

thermally conditioned

- heat at various temps to remove volatile contaminants => unstable baselines

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73
Q

isothermal

A
  • GC
  • constant temp over time
  • faster for samples with less variety of chemicals with different volatlities
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74
Q

varied temp over time (vs. isothermal in GC)

A

programmed

  • weak interactions (low bp) elute first
  • strongest interactions (highest bp) elute last
  • sharper peaks in less time
75
Q

the _____ of mobile phase in liquid chromatography is used to adjust retention time

A

composition

  • strong mobile phase: leads to weak analyte on the stationary phase; analyte prefers mobile phase
  • weak mobile phase: leads to highest retention of analyte on the stationary phase; analyte prefers stationary phase
76
Q

ion-exchange chromatography

A

ions separated by adsorption to solid support with fixed charges at surface
depends on:
- pH
- type of competing ion
- type of fixed charge on the stationary phase
- density of fixed charge on the support

77
Q

size exclusion chromatgraphy

A
  • stationary phase based on physical differences not chemical
  • mobile phase has no weak or strong phase; determined by analyte solubility and stability, support and column
78
Q

porous with inert surface and range if pore sizes similar to analytes of interest; cross-linked dextran or agarose, polyacrylamide gel, modified silica or glass beads

A

size exclusion chromatography

79
Q

this chromatography is used to identify intact complexes: lipoproteins, Ag-Ab complexes

A

SEC

80
Q

affinity chromatography separaton by retention of analytes based on…

A

selective reversible biologically related interactions

- Ag-Ab, enzyme-substrate, enzyme-inhibitor

81
Q

ths type of cromatography has two different mobile phases to accomplish separation; one soid support

A

affinity chromatography

82
Q

method of choice for most routine searation and analysis methods

A

HPLC (high [perfermonace liquid chromatography)

83
Q

this uses more efficient psupports than original LC methods

A

HPLC

  • narrower peak
  • better separation
  • lower limits of detection
84
Q

this has to be “sparged”

A

HPLC solvent reservoir; to remove dissolved air bc it interferes w detector response

85
Q

sample injector

A

reproducible, no carry-over, range of volumes

86
Q

isocratic elution

A

same mobile phase throughout

87
Q

gradient elution

A

mobile phase composition is varied overtime to control separation

  • achieved through solvent programming
  • start with weak mobile phase (allow weak retention to interact)
  • profress to stronger mobile phase (elute chemicals with moderate/high retention)
88
Q

glycation of Hb

A
  • glucose enters RBC and naturally binds or glycates HbA1

- this increases neg charge and changes in Hb size

89
Q

this is measured for effectie monitoring of long-term glucose control in individuals with diabetes mellitus

A

% HbA1c

90
Q

screening method for detection and preliminary identification of hemoglobinopathies

A

HPLC or capillary electrophoresis

91
Q

accurate mass

A

experimentally determined mass

- value obtained from mass spec m/z ratio

92
Q

molecular mass

A

calculated mass of a compound based on the weighted average of the masses of all isotypes of the elements present; AKA average mass

93
Q

the calculated mass based in the accuratre masses of the most abundant stable isotopes of the elements present

A

monoisotopic mass

94
Q

the nearest integer value of the monoisotopic mass

A

nominal mass

95
Q

components of mass spec

A

inlet system, ion source, mass analyzer, detector, data system

96
Q

a plot of the intensities of the ions as a function of their m/z values

A

mass spectrum

97
Q

this relies on adjusting RF and DC voltages to allow ions to pass through based on m/z

A

quadrupole

98
Q

the principle is based on speed of ions relative to their mass; lighter ions are accelerated to a higher velocity than heavier ions

A

time of flight

99
Q

ability of mass spec to detect an ion; how small an amount can be analyzed

A

sensitivity

100
Q

measure of the ability of analyzer to separate ions with different m/z values + how sharply defined are the peaks, how separated are they from each other?

A

mass resolution

101
Q

determines the abundance of the ions of different m/z after they have been separated by the mass analyzer

A

ion detector

102
Q

ion detector characteristics

A
  • low or no noise
  • high stability
  • simultaneous detection
  • wide mass-range response
  • mass-independent response
  • fast response
  • short recovery time
  • high saturation level
103
Q

what is a tandem mass spec?

A

2 mass analyzers (in space)

- tandem in time = one mass analyzer ONLY

104
Q

characteristics of a single mass analyzer

A
  • see all m/z in a scan
  • look for unknowns
  • BUT high potential for overlapping m/z
  • BUT poor specificity
105
Q

characteristics of a tandem mass analyzer

A
  • choose a specific target m/z
  • fragments in collision cell and scans fragment ions
  • good specificity due to fragmentation

can generate structural info

106
Q

this is a chemical propert of proteins

A

absorb UV light

107
Q

UV absorption at 280 nm

A

aromatic rings in amino acids

- direct spec

108
Q

disadvantages of direct spec

A
  • depends on amino acid composition

- uric acid and bilirubin interfere at 280 nm

109
Q

UV absorption at 200-225 nm

A
  • wavelength max for peptide bonds
  • 10-30 x higher absorptivity than 280 nm
  • disadvantages = interference at <220 nm
  • remove rea (low MW)
110
Q

this test is for serum test protein only

A

biuret test

111
Q

disadvantage of biuret test

A
  • cannot measure low protein levels so not useful for CSF or urine samples
112
Q

Lowry or BCA

A
  • for serum, CSF, and urine total protein
  • modifications to Biuret method (to be more sensitive to lower conctns)
  • most versatility for detecting different sample types
113
Q

dye-binding

A
  • based on chemical charge
  • anionic dyes bind to cationic group of basic amino acids (histidine, arginine, lysine) & free AA terminal groups
  • for urine, CSF total protein
114
Q

turbidity & nephelometry

A
  • chemical precipitation
  • use trichoroacetic acid (TCA) or sulfosalicylic acid (SSA) to precipitate protein to prepare an insoluble protein suspension
  • more sensitive than dye-binding
  • for urine total protein
115
Q

turbidimetry

A
  • measures reduction of light which passes through cuvet
  • transmitted at 180 degree angle
  • detection limit is 20-30 microgram/mL
116
Q

nephelometry

A
  • measures scattered light
  • at right angle (90 degrees) or forward angle
  • detection limit is ~10 microgram/mL
  • better than turbidimetry bc no interference from scattered light
117
Q

reduced total protein (4)

A
  • inadequate protein intake: malabsorption, malnutrition
  • inadequate synthesis: chronic liver disease
  • protein loss: nephrotic syndrome, diarrhea, severe burn
  • dilution (IV line); artificial way to lose protein
118
Q

elevated total protein (2)

A
  • decreased blood volume: dehydration (FIRST thing u think about; proteins are not truly high, just seems this way bc lower blood volume)
  • increased protein production: multiple myeloma, lupus, rheumatoid arthritis, other collagen diseases, chronic infections, sarcoidosis
119
Q

bisalbuminemia

A
  • genetic variant
  • hereditary mutation
  • no associated pathology
  • fast and slow variants
120
Q

causes of hypoalbulinemia

A
  • malnutrition, inflammation
  • liver, kidney, and GI disease
  • pregnancy
121
Q

what is albumin?

A
  • negative acute-phase protein
  • maintains oncotic pressure
  • carrier protein
122
Q

most abundant protein in serum

A

albumin

- anionic protein

123
Q

total serum protein = ?

A

albumin + serum globulins + other serum proteins

124
Q

how to measure specific proteins

A
  • immunoprecipitation (aggregation of immune complexes; Ag:Ab)
  • ex: haptoglobin, transferrin, alpha1antitrypsin, complement
  • specific proteins in sample combine with their specific Abs in the reagent = insoluble complexes
  • aggregates increase turbidity and light scattering is proportional to [protein]
125
Q

measuring total albumin

A
  • ~60% of serum protein
  • binds anionic dye bromocresol green or purple dye
  • read within 30 s because not specific
126
Q

how do enzymes accelerate a chemical rxn?

A

by lowering the activation E required for the reaction to occur to form P

127
Q

where regulator molecules can bind on an enzyme

A

allosteric site; unlike the active site, not all enzymes have this

128
Q

T or F. enzymes alter the final rxn equilibrium

A

F! they don’t

129
Q

this describes the relationship between velocity of enzyme reaction and [S]

A

Michaelis-Mentn (M-M)

V = Vmax [S] / Km + [S]

130
Q

What is Km?

A

[S] at 1/2 Vmax

  • describes E affinity for S
  • M-M constant specific for E and S
131
Q

What is Vmax?

A

maximum rxn velocity

132
Q

[S] must be __ Km to ensure detection of maximal E activity

A

> 20x Km

133
Q

what does low Km mean?

A

high affinity of enzyme for S!

134
Q

factors affecting rate of ALL enzyme reactions (potential sources of assay error)

A
  • substrate concentration
  • enzyme concentration
  • pH
  • temperature
135
Q

1st order kinetics

A
  • V proportional to [S]
  • enzyme readily binds at low [S]
  • velocity proportional to [S]
  • if [S] <20x Km, S depletes and enzyme rxn velocity decreases (linearity falls off)
  • enzyme activity underestimated
  • dependent on [S]
136
Q

0 order kinetics

A
  • V proportional to [E]
  • no further addition of S will increase enzyme activity
  • [S] > 20 Km ensures max rxn rate
  • detect max E activity, independent of [S]
137
Q

effect of enzyme concentration at fixed [S]

A
  • at low [E], reaction rate (v) is proportional to [E]

- if [E] > [S], rxn velocity will become non-linear, results will be invalid

138
Q

Quality management system ensures: (5)

A
  • correct sample collected from correct patient using correct methods
  • specimens/samples transported properly to correct location
  • correct test performed on correct sample
  • ensure only valid results are reported (QC to assess test performance)
  • results are reported in a timely manner
139
Q

how is test interpretation done in a clinical diagnostic lab?

A

by comparing the patient result with the relevant set of reference values, known as a “Reference Range” or “Reference Interval” or “Reference Values”

140
Q

diagnostic performance of a lab is measured by

A
  • diagnostic sensitivity

- diagnostic specifcity

141
Q

diagnostic performance of a lab depends on:

A
  • reference interval selection

- degree of separation between healthy and diseased populations

142
Q

range (interval) of values of a physiological measurement in a defined population of individuals

A

reference range/interval

143
Q

when is AST ordered?

A

to detect liver damage/distinguish damafe to liver vs other tissues

144
Q

when is ALT ordered?

A

to screen for liver damage (parenchymal cells)

145
Q

clinical significance of increased serum AST

A 
- viral hepatitis (100x when acute)
 > AST rises before sign and symptoms appear
- cirrhosis (due to alcohol)
- myocardial infarct
- muscular dystrophy
- strenuous exercise, drugs
- NOT EXCLUSIVE TO LIVER DAMAGE
146
Q

phosphatases

A

ALP and 5’-NT

147
Q

when is ALP ordered?

A

to screen or monitor treatment of liver or bone disorder

148
Q

clinical significance of increased ALP

A
  • bone disease: Paget’s disease, rickets, osteosarcoma, etc.
  • hepatobiliary dsease: hepatitis; extrahepatic biliary tract obstruction
  • placental ALP, Regan isoE, Nagao isoE (tumors)
149
Q

when is 5’-NT ordered?

A

suspected biliary obstruction

150
Q

clnical significance of increased 5’-NT

A
  • diagnostic for biliary obstructive jaundice (cholestasis); persists longer than ALP
  • destruction of liver cells
    > higher with viral hepatitis > alcoholic liver disease, liver cirrhosis
    > liver tumor
    > use of liver-damaging drugs
151
Q

GGT assay

A

gamma-glutamyl-p-nitroanalide + glycyglycine

152
Q

when is GGT ordered?

A
  • to differentiate between bone or liver cause of increased ALP
  • to detect liver disease and/or alcohol abuse
153
Q

clinical significance of increased GGT

A
  • hepatobiliary disease
    > biliary tract obstruction (Increase 5-30 x)
    > choleostasis, pancreatitis, neoplasms
    > hepatitis
  • drugs that induce microsomal enzymes
    > warfarin, phenobarbitol, phenytoin, rifampicin
    > alcohollll: remains increased even after 3-4 weeks abstinence
154
Q

T or F. GGT is more sensitive and persists longer than other enzymes

A

T!

- also, GGT assays differentiates source of increased ALP

155
Q

phosphatases

A 
can transfer (R2-O-PO3)
or hydrolyse (making a PO4, ROH) a phosphate gorup
156
Q

If you have too much product accumulating, can cause _________ of a rxn

A

inhibition

  • ALP inhibited by phosphate
  • adenosine inhibits 5’NT if AMP + H2O
157
Q

Glutathione

A

involved in tissue building and repair, making chemicals and proteins needed in the body, and in immune system function.

158
Q

Amylase

A
  • digestion of starch to glucse, maltose, dextrins
  • only alpha -1,4 linkage (glycosidic bond)
  • acinar cells (pancreas and salivary glands)
  • isoenzymes P & S
  • low MW so appears in urine
159
Q

when is AMS (amylase ordered?)

A

to monitor/diagnose pancreatic disease

160
Q

increase in AMS

A
  • acute pancreatitis (increase >10X is diagnostic but also with non-pancreatic tumors)
  • magnitude of increase not correlated with severuty
  • urine AMS is more frequently elevated
    > reches higher levels and persists longer
160
Q

increase in AMS

A
  • acute pancreatitis (increase >10X is diagnostic but also with non-pancreatic tumors)
  • magnitude of increase not correlated with severuty
  • urine AMS is more frequently elevated
    > reches higher levels and persists longer
161
Q

T or F. 20% of patientrs with acute pancreatitis have normal AMS activity

A

T!

162
Q

AMS has good _____ but poor _______

A

good sensitivity but poor specificity

163
Q

why is it difficult to diagnose increase AMS when less than 10X?

A

could be due to:

  • renal fdailure
  • diabetic ketoacidosis
  • GI disorders or obstruction
  • viral infection (mumps, AIDS)
  • acute alcoholism
  • drugs
164
Q

progressive decrease in AMS

A
  • chronic pancreatitis
  • cells destroyed
    > alcoholism, trauma, obstruction, CF
165
Q

hydrolysis of dietary triglycerdes at 1 and 3 positions

A

lipase (LIP)

166
Q

where are LIPs located

A

pancreas 100x > other tissues

- isoenzymes L1 and L2

167
Q

this inhibits LPS

A

Hb (avoid hemolysis in Lipase assays)

168
Q

when is lipase ordered?

A

to monitor or diagnose pancreatic disease

169
Q

increase in LIP significance

A
  • acute pancreatitis
    > more specific than AMS (stays high longer)
    > differentiates increase serum AMS
  • following biliary tract endoscopy
  • morphine
170
Q

decrease in LIP significance

A
  • permanent change to pancreatic cells
  • risk of developing diabetes
  • risk inability to digest fats (greasy stool)
  • progressive disease => irreversible damage => death
171
Q

trypsinogen immunoassay

A
  • ImmunoReactive Trypsin (RT)

- blood, serum, plasma

172
Q

trypsin catalytic assay

A
  • synthetic peptide substrates

- stool, duodenal fluid

173
Q

when is trypsin ordered?

A

to screen for cystic fibrosis and pancreatic insufficiency

174
Q

clinical significance of decreased trypsin

A
  • decrease stool = CF

- decrease plasma IRT = pancreatic insufficiency, diabetes

175
Q

clinical significance of increased trypsin

A

increased plasma IRT

  • acute pancreatitis
  • neonates with CF
  • chronic renal failure
176
Q

acetylcholinesterase

A
  • true cholinesterase (I)
  • hydrolyzes acetylcholine to terminate depolarization of post-synaptic muscle cell
  • RBC, lung, spleen, nerves, brain gray matter
177
Q

Pseudocholinesterase

A
  • CHE, (II), serum or butyryl cholinesterase
  • unknown role, synthesized in liver
  • liver, plasma, pancreas, heart, brain white matter
  • genetic variants = decrease activity against choline esters; clinicall useful
178
Q

when is cholinesterase ordered?

A

to detect exposure to pesticides or inherited CHE deficiency; test liver function

179
Q

significance of decased CHE activity

A
  • insecticide poisoning
  • atypical CHE variant = fails to destroy muscle relaxant (succinylcholine) used in surgery = prolonges paralysis of resp muscle
  • reduced liver synthetic capacity = acute hepatitis, adv. cirrhosis and cancer
180
Q

creatine kinase

A
  • energy storage in muscle

- brain, heart, striated muscle (very low in liver and RBC)

181
Q

why must we protect the SH groups of CK active site?

A

CK inactivated by heat, sunlight, increase in pH

182
Q

when is CK ordered?

A

to detect muscle damage

183
Q

increase CK significance

A
  • muscular dystrophy or MD (CK-3); Duchenne’s MD (CK-2, CK-3)
  • damage to blood-brain barrier (CK-1)
  • acute MI (NOT SPECIFIC)

MLSCI 262 (21 decks)

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