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Clinical Chem II spring > Porphyrins and Hgb > Flashcards

Porphyrins and Hgb Flashcards

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1
Q

Describe porphyrins
shape?
compromised of?
joined by?

A

cyclic structures compromised of 4 pyrole rings joined by methine bridges

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2
Q

chelation of ferrous iron

A

to protoporphyrin ring, creates heme

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3
Q

Heme

A

binds oxygen, is a prothestetic group

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4
Q

Porphyrias

A

disorders that result from distrubance in heme synthesis

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5
Q

Hgb molecules

A

bind/deliver/release oxygen

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6
Q

Hgbopathies

A

qualitative defects

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7
Q

Thalassemia

A

quantitative defects

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8
Q

Porphyrins
chemical intermediate in…
pigments called?

iron is chlated into?

excess?

A

Chemical intermediate in synth of hgb/mygb/respiratory pirgments called cytochromes

iron is chelated into porph ring

excess compounds

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9
Q

Porphyrionogens
reduced…
intermediates in…

what happens w exposure to air?

A

reduced compounds that are intermidiate in synth of heme

oxidized on exposure to air in porphyrins

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10
Q

Isomers
how many for every porphyrin compound?

what types occur naturally?

A

4 isomers for every porphyrin compound

type I and III naturally occur

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11
Q

Whats special about type III isomer?

A

only one to form heme

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12
Q

T/F in some disorders the non functional type I isomer may be found in excess body fluids and tissues

A

true

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13
Q

Porphyrin properties
photo……due to….
color due to?

aqueous sol varies with…..

A

photoactive due to conjugation w tetrapyrole ring

dark red color due to strong absorbance (600-650nm)

aqueous sol varies w # of carboxylic acid present in substance

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14
Q

Uroporphyrin (Uro)

A

8 carb groups, most soluble in H20 excreted renally

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15
Q

Coprophyrin (Copro)
how many carb groups
solubility?
in?

A

4 carb groups, interm sol

blood and urine/feces

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16
Q

porphyrin groups with 2 carbs
influences?

A

least soluble

influences type of specimen selected to measure

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17
Q

Synthesis of heme
all cells contain..
primary sites?

A

all cells contain hemoproteins and can synth heme

BM/Liver primary site

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18
Q

how many molecules of heme is produced from 8 molecules of Alpha ALA?

A

one molecule of heme produced

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19
Q

What synthetic rxn require energy?

A

First and last three (in mitochrondria) others in cytosol

negative feedback mechanism

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20
Q

Control rate of heme
where?
through regulation of?

increase in pool of hepatic heme?

decreased heme?

A

in liver

through regulation of ALAS

increase in pool of hepatic heme decrease ALAS pool

ALAS production increase decreases heme

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21
Q

In bone marrow what controls rate of heme synthesis?

A

erythrocytes and other enzymes in pathway

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22
Q

Disorders of bio heme synthesis
most are?

A

most auto dominannt with 50% reduction in activity or affected enzymes

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23
Q

Enzyme defects
excess accum….

A

excessive accumulation/excretion of intermediate compounds that produce symptoms

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24
Q

Neuopsychiatric symptoms

A

abdominal pain, nausea, constipation

excess in early precursors in oath of heme synth (ALA/PBG)

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25
Q

Porph symptoms
hint (a/a)

A

ADP/AIP

26
Q

Cutaneous
symptoms: p/b/f

excess….
c/p/e/x

increased fragility of light exposure in?

burning of light exposed skin in?

due to ?

A

sympt

photosensitivity, blisters, facial hair

excess porphyrin intermediates
CEP,PCT,EPP,XLPP

increased fragility of light exposure in CEP/PCT

burning of light exposed skin in EPP/XLPP

due to absorption of light of porhyrins

27
Q

Neurocutaneous symptoms
excess…
h/v

A

excess precursors/intermediates
HCP/VP

28
Q

Acute porphyrias
causes what kind of attacks?
neruophyciatirc?
neurocutaneous?

most common?

A

neurological/serious acute attacks

ADP/AIP - neurophychiatric
HCP/VP - neurocutaneous
AID - most common acute porphy, 80% asymptomatic

29
Q

Non acute present as chronic (cutaneous)
c/p/e/x

most common?

extreme photosensitivity

A

CEP,PCT,EPP,XLPP

PCT most common

CEP - extreme photosensitivty

30
Q

Secondary Porphyious
increased excretion of?
caused by?
examples that cause excess excretion/
inhereited?

A

increased excretion of urinary porphyrins

caused by another disorder/toxin interferring w heme formation

liver disease/lead posioning excess urinary porph excretion

inherited disorder of bilirubin met

31
Q

Acute porphyria testing
determin what in urine?

if positive?

A

Determin PBG in urine

if positive - ID ALP, differentiate AIP/VP/MCP

32
Q

Cutaneous porphyria testing
measured in?
increased excretion of porph pattern diagnostic for?

…..in plasma and whole blood?

A

measure porh in random/timed urine

increasse excretion of porph pattern in diagnostic for PCT/CEP

EPP/XLPP is plasma and whole blod

33
Q

Analytical methods
wat
H
chrom
Fec

A

watson-schwartz assay
HPLC
Chromotographic
Fecal HPLC/flourecnese

34
Q

Specimen requirements

A

protected from light
unpreserved urine
4 degrees - 48 hr
neg 20 for weeks

fecal frozen 20 degrees

whole blood EDTA protect from light 4 degrees

35
Q

Hgb

A

oxy transport to tissues/CO2 back to lungs

carried to all tissues of body by erythroctes

major buffer systom of body

36
Q

Hgb shape

A

spherical molecule

2 major parts, central oxy non protein molecule

2 glob chains, Alpha and beta

37
Q

Majority of adults have what Hgb

A

Hgb A and A1

two alpha two beta

Hgb A2 <3% (two alpha two delta)

Hgb F (2 alpha 2 gamma)

38
Q

Neonate hgb

A

Hgb F 2 alpha two gamma
main hgb during fetal life and 60% of hgb at birth

39
Q

Hgbopathies defined

A

defect in structures

40
Q

Thalassemias defined

A

defect in rate and quant of production

decreased or absent chains
alpha and beta
micro/hypo
autodom hetero

41
Q

what chromosome are Alpha genes?

all others?

A

a genes on chrom 16

others 11

42
Q

T/F in most people, the alpha gene is duplicated A1/A2 indentical alpha genes in Hgb A,A2 and F

A

ture

43
Q

non alpha genes subject to ?

A

delta, beta, gamma

subject to non homologous cross over

fused/hybrid chains

44
Q

hgb lepore
: what type of chains

Hgb kenya: chains?

A

delta beta chains

kenya: gamma beta chains

45
Q

Hgbopathies divided into groups based on?

A

based on genetics, 4 groups

AA subsitutions
AA deletions
Elongated chains/frameshift (constant spring)
Fused/hybrid chains

46
Q

Most abnormalities are?

A

amino acid subsittutions

2/3 hgbopathies affect Beta chains

47
Q

More on thalassemia
absent/deminished?

A

absent/deminished synth of polypeptide chains

alpha thal: no alpha chains …etc

48
Q

Synth and degradation of heme
synth occurs in?
normally requires synth in?
glob synth in
what supply?

A

hgb synth occures in immature rbcs/bone marrow

norm synth requires synth in mitochonrida (heme)
glob synth in cytoplasm
iron supply

49
Q

Intravascular vs extravascular

A

I: blood vessles
E: cells/liver

50
Q

Hgb S

A

most common in US
sickle cell HbAS
black/african population

solubility test

HGB S IS BETWEEN A AND A2

51
Q

Hgb C

A

west africa/ghana
target cells/crystals
cellulose electrophor

moves w Hgb A2

negative tube sol

52
Q

Hgb SC

A

most common mixed hgb B-s/B chains

no normal B chains to produce A
tube sol postive

53
Q

Hgb E

Hgb D

A

asian microcytes somewhat unstable

D: given to varient similar to S that is tube negative, homozygous rare, found in india

54
Q

Thal minor

A

hetero, asymptom, iron deficiencies

55
Q

Thal Major

A

lethal before birth, complications

56
Q

Alpha thal
chromosome?

hydrops fetalis?

hgb M?

silent carriers?

A thal trait?

A

chrom 16 4 genes

hydrops fetalis: alpha chain absense, hgb barts

Hgb M: mod heme anemia

Silent carriers: missing 1 gene

A thal trait: two gene deletion

57
Q

Beta thal
caused by?
homozgous -…..causes?

Hetero?

B+
B0

A

caused by mutations

homozygous - major - cooley anemia, crippling in childhood, bone deformities

hetero - minor

B+ reduced chains - most common severe
B0 absent chains - dec hgb anemia

58
Q

tube Solubility test

fasle neg?
false pos?

A

screen for sickle cells
sickling hgb means you cant read through the tube (looks turbid)

false neg due to transfusions/hgb F

false pos: whole blood vs packed rbcs

59
Q

Cellulose acetate

A

alkaline buffer

electro mobility: AFSC

universal screening for newborn hgb op

60
Q

Other tests

A

citric agar, Hgb A2 quant, acid elution, Hgb F quant

61
Q

DNA

A

increase sensititivy and specificity
higher cost
prental diagn of thal major

62
Q

Myoglobin

A

skeletal/caridac muscle

damage to muscles increase serum urine myoglobin

rapid renal clearance - increase conc = renal failure

can cause reaction like rhabdo/mI/Muscle dystrophy

Clinical Chem II spring (16 decks)

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