Partial 2 - Enzymes Flashcards

1
Q

IU/L

A

Amount of enzyme necessary to catalyze the conversion of 1μmol of substrate per minute

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2
Q

SI unit (mol/sec)

A

Amount of enzyme that will catalyze the conversion of one nanomole of substrate per second (nanokatal)

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3
Q

Enzyme concentration may change if:

A
  • Tissue is undergoing injury
  • Tissue is under stress - corrective response
  • Tissue is under direct damage: reversible - small molecules; permanent - total leakage
  • Tissue Stimulation
  • Tissue Proliferation - natural cell turnover
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4
Q

How many isoenzymes Lactose dehydrogenase have?

A

5, LDH1 - LDH5

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5
Q

Where in the cell is LDH found and what is the function

A

Found in cytoplasm of every cell and it catalyze important step glycolysis

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6
Q

LDH subunits

A

H (heart) subunit (gene on chromosome 12)

M (muscle) subunit (gene on chromosome 11)

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7
Q

Creatine Kinase (CK) location in cell

A

Mitochondria

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8
Q

CK function

A

Function in muscle cells to catalyze the transfer of high energy bond from ATP to creatine and irreversible reaction during active muscle contractions

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9
Q

CK isoenzymes and their distributions

A

CK-MM - heart (79%) and muscle (99%)
CK-MB - trace level in muscle (1%) and high level in myocardium (20%)
CK-BB - throughout the brain (97%) and muscles (1% - cardiac muscle)

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10
Q

First sign of acute MI biomarkers

A

First sign is increased myoglobin (small size) and CK-MB isoforms (normal serum trace levels)

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11
Q

CK-MB :
Beginning of elevation
Max. peak
Presence

A

Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: 36-48h

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12
Q

Troponins:
Beginning of elevation
Max. peak
Presence

A

Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: <10 days

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13
Q

Myoglobin:
Beginning of elevation
Max. peak
Presence

A

Beginning of elevation: 1-4h
Max. peak: 6-7h
Presence: <24h

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14
Q

LDH:
Beginning of elevation
Max. peak
Presence

A

Beginning of elevation: 6-12h
Max. peak: 24-48h
Presence: 6-8 days

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15
Q

Skeletal muscle disease useful biomarkes

A

CK

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16
Q

Acute muscle enzyme release causes

A
Surgery
Trauma
Crush injuries
Excessive muscular contractions
Hyperthermia
Viral myositis
Toxins exposure
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17
Q

Muscular dystrophies

A

Higher portion of CK-MB in muscle than normal (high tissue turnover)

18
Q

Long distance runners

A

High non-cardiac CK-MB

19
Q

Amylase (Amyl) isoenzymes

A

Pancreas, salivary gland, testis, ovary

20
Q

Amylase reference range

A

20-160 U/L

21
Q

Lipase (Lip) reference

A

<200 U/L

22
Q

Acute pancreatitis diagnosis

A
  • Amylase and lipase level increases after few hours after onset, remain elevated for 36-48h, activity isn’t correlated with severity
  • Clinical sensitivity for amylase and lipase - 90% when blood is sampled in the first 36h
23
Q

Pancreatic enzymes in other disorders

A
Pancreatic trauma
Abdominal surgery
Carcinoma
Diabetes mellitus
Viruses injury
Drugs
Perforated ulcer
Peritonitis
Renal failure (Amylase and trypsin are excreted with urine)
24
Q

Liver Function Tests

A
  • ALT or SGPT
  • AST or SGOT
  • LDH
  • ALP, GGT
  • Bilirubin (total and direct)
  • Total protein (albumin and globulins)
  • Albumin (main protein made by liver)
  • PT (pro-thrombin time)
25
Q

Normal ALT and AST levels

A

10-40 U/l

26
Q

Classic ALT rise

A
  1. Liver injury
  2. Muscle myolysis
  3. Ischemia
  4. Myocardial infarction
27
Q

Classic AST rise

A
  1. 100x toxic liver injury by dead cap
  2. 10x prolonged acute liver inflammations, crash injuries, muscular dystrophy, rhabdomyolysis in case of poisoning and drug use (statins)
  3. Mononucleosis
  4. Hypoxia, heart failure, pancreatitis
  5. 2-3x in portal circulation stagnation, cholestasis, acute renal failure
28
Q

De Ritis Ratio AST/ALT

A

AST/ALT>1

29
Q

Increases in both ALT and AST however with prominent ALT rise informs about?

A

Slight damage of liver cells

30
Q

Prominent AST rise in de Ritis ratio indicates presence of?

A

Necrosis areas in liver or muscles

eg. 2day after AMI AST/ALT>2

31
Q

De Ritis Ratio in acute disorders (viral, infections)

A

Higher ALT than AST and de Ritis ratio is <1

32
Q

De Ritis Ratio in chronic disorders (severe cells damage)

A

de Ritis ratio >1

33
Q

Aloholic liver disease de Ritis ratio

A

de Ritis ratio >6

34
Q
Alkaline Phosphatase (ALP) levels in:
Adults, Children and Newborns
A

Adults: 20-70 U/l
Children: 20-150 U/l
Newborns: 50-165 U/l

35
Q

When and why does ALP rise (Physiologic)

A
  1. Placenta ALP: Pregnant women
  2. Bones ALP: Grow-up process
  3. Intestine ALP: After the meal in people with O or B blood group, During menstruation, Estrogen use, Fatty meal
  4. Bones ALP: Convalescence, bones set up, after surgeries
36
Q

When and why does ALP rise (Pathologic)

A
  1. Fractions of liver isoforms: bile and macromolecular: liver disease
  2. Bone ALP: Primary and secondary bone diseases (osteomalacia, osteoporosis)
  3. Ectopic isoenzymes: Neoplastic diseases (over expression of genes coding placenta, intestines and germinal cells isoenzymes)
37
Q

If source of increased ALP is unclear, what should you order?

A

GGT or 5’NT

38
Q

Gamma-glutamylotransferase (GGT) reference for men and women

A

Men: 18-100 U/l
Woman: 10-66 U/l

39
Q

What causes raise in GGT

A
  1. Acute and chronic liver, biliary ducts and pancreas problems especially combined with stasis in ducts flow
  2. Slight rise is observed in MI
  3. GGT rise is induced in some drugs treatment (barbiturates, fenytoin, estrogens)
  4. GGT rises in alcohol use
40
Q

Acute hepatitis major biochemical finding

A

ALT>AST