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Clinical Chemistry (CC 1) > (M) Lec 5: Amino Acids (P3: Other Proteins + Lab Measurements) > Flashcards

(M) Lec 5: Amino Acids (P3: Other Proteins + Lab Measurements) Flashcards

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1
Q

Other Proteins of Importance

  • Includes: Myoglobin, CK-MB, and Troponin
  • For the diagnosis of myocardial infarctions (elevated)
A

Cardiac Markers

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2
Q

Other Proteins of Importance

  • For cell adhesion, tissue differentiation, growth, wound healing, and nutrition (nutritional marker)
  • Found in plasma and the cell surface (synthesized by liver hepatocytes, endothelial cells, peritoneal macrophages, and fibroblasts)
A

Fibronectin

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3
Q

Other Proteins of Importance (Fibronectin)

  • A glycoprotein produced at the boundary between the amniotic sac and decidua
  • Used to help predict the short term risk of premature delivery (increased levels)
  • Normally detectable in amniotic fluid and placental tissue during early and normal pregnancy
  • No longer detectable after 24 weeks
A

Fetal Fibronectin

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4
Q

Other Proteins of Importance

  • Produced by the adipocytes
  • Has an inverse correlation with body mass index
  • Lower levels correlate with an increased risk of heart disease, type 2 diabetes, metabolic syndrome, and obesity
A

Adiponectin

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5
Q

Other Proteins of Importance

  • aka Prostaglandin D Synthase
  • Established as an accurate marker of CSF leakage (fluid in the nose)
  • Potential marker in detecting impaired renal function (GFR)
  • Promising marker in the diagnosis of perilymphatic fluid fistulas
A

B-Trace Protein

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6
Q

Other Proteins of Importance

  • A biochemical marker of bone resorption detected in serum and urine
  • Fragments of Collagen Type 1
  • Useful for monitoring response to antiresorptive therapy (if still elevated, it means that the therapy is not effective)
  • Bone turnover increases at menopause
  • **Non-invasive **and can be repeated
  • ECLIA is used (chemiluminescence)
A

Cross-Linked C-Telopeptides (CTX)

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7
Q

Other Proteins of Importance

  • Produced and destroyed at a constant rate, making it a new marker for early assessment of changes in glomerular filtration rate
  • Freely filtered by the glomerulus and almost completely reabsorbed and catabolized by the proximal tubular cells
  • Not affected by muscle mass, gender, age or race unlike creatinine nor affected by most drugs, infections, diet, or inflammation
  • Used as an alternative to creatinine and creatinine clearance to screen for and monitor kidney dysfunction
A

Cystatin C

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8
Q

Other Proteins of Importance

  • Insoluble protein due to an altered secondary structure
  • Characteristically stains with congo red
  • The fibrils may infiltrate the heart, blood vessels, brain, peripheral nerves, kidneys, liver, spleen, and intestine causing wide spread organ failure
A

Amyloid

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9
Q

Other Proteins of Importance

Refers to conditions where amyloid proteins are abnormally deposited in organs and/or tissues

A

Amyloidosis

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10
Q

In measuring total protein, should the specimen be from a fasted patient or no?

A

Non-fasting (diet does not affect it)

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11
Q

Other Proteins of Importance

These amyloid proteins can be used to differentiate Alzheimer’s (increased) from other cases of dementia

(2 answers)

A

Amyloid B42 and Tau Proteins

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12
Q

Lab Measurements: Total Protein

  • The standard reference method but it is not commonly performed in the lab because of its complexity
  • It is time-consuming to perform
  • It is an indirect method: it measures ammonium ions, not the protein itself (amount of proteins = amount of nitrogen and ammonia)
  • Is divided into 3 major steps: Digestion, Distillation, and Titration/Nesslerization
A

Kjeldahl/Digestion Method

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13
Q

Lab Measurements: Kjeldahl/Digestion Method

Identify what step?
- Protein + Sulfuric Acid = Ammonium Sulfate

A

Digestion (Step 1)

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14
Q

Lab Measurements: Kjeldahl/Digestion Method

Identify what step?
- Ammonium Sulfate + Sodium Hydroxide = Ammonia and Sodium Sulfate
- Ammonia is distilled off and collected in a flask with boric acid
- Ammonia + Boric Acid = Ammonium Borate

A

Distillation (Step 2)

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15
Q

Lab Measurements: Kjeldahl/Digestion Method

Identify what step?
- A colorimetric method
- 1 gram of N = 6.54 grams of protein (conversion factor)

A

Titration/Nesslerization (for the first bullet)

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16
Q

Lab Measurements: Total Protein

Around how many percent of Nitrogen is contained in proteins?

A

15.1% - 16.8%

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17
Q

Lab Measurements: Total Protein

  • There is color formation/color change
  • Uses spectrophotometry to determine the absorbance
A

Colorimetric Method

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18
Q

Lab Measurements: Total Protein (Colorimetric)

  • The most widely used and recommended by IFCC (Intl. Federation of CC)
  • Is highly specific for proteins and peptides
  • It directly measures protein concentrations in the sample
  • Reagent is composed of alkaline copper sulfate (source of cupric ions), Tartrate salt (stabilizes cupric ions), and Potassium iodide (prevents autoreduction of cupric ions)
  • pH is alkaline due to copper sulfate
  • Hemoglobin and bilirubin can interfere with the results
A

Biuret Method

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19
Q

Lab Measurements: Total Protein (Colorimetric)

What method produces this?
- Reagent + Protein = Pink to Reddish Violet
- Absorbance is read at 540 nm

A

Biuret Method

20
Q

Lab Measurements: Total Protein (Colorimetric)

  • Has the highest analytical sensitivity
  • Reagents: Phosphotungstic-molybdic acid or phenol reagent
A

Folin-Ciocalteu (Lowry) Method

21
Q

Lab Measurements: Total Protein (Colorimetric)

What method produces this?
- Oxidation of phenolic compounds such as tyrosine, tryptophan, and histidine
- Gives a deep blue color

A

Folin-Ciocalteu (Lowry) Method

22
Q

Lab Measurements: Total Protein (Colorimetric)

  • Very sensitive because it can detect as low as 0.1-0.5µg of protein
  • Produces a blue color
A

Coomassie Brilliant Blue

23
Q

Lab Measurements: Total Protein (Colorimetric)

  • Reagent + Proteins (primary amines) = Violet
A

Ninhydrin

24
Q

Lab Measurements: Total Protein

  • Utilizes sulfosalicylic acid and or trichloroacetic acid
  • Measurement depends on the formation of a uniform fine precipitate which scatters incident light in a suspension or blocks light
A

Turbidimetry and Nephelometry

Not common for serum proteins but rather for urine and CSF proteins

  • Scatters incident light in a suspension (nephelometry)
  • Blocks light (turbidimetry)
25
Q

Lab Measurements: Total Protein (Turbidimetry Table)

  1. Heavy flocculation/clumping
  2. Moderate degree of turbidity
  3. Very faint precipitate
  4. Clear (no turbidity)
  5. Small degree of turbidity
  6. Heavy turbidity

A. Negative
B. Trace
C. 1+
D. 2+
E. 3+
F. 4+

A
  1. F
  2. D
  3. B
  4. A
  5. C
  6. E

Study the protein contents in the table, thanks

26
Q

Lab Measurements: Total Protein

  • An alternative test
  • Based on the measurement of refractive index due to solutes in the serum (proteins)
  • Accurate for serum proteins as dissolved solutes for levels greater than 2.5 g/dL
  • In urine, it is used to determine specific gravity
  • For total protein, it is only used if the specimen is either serum or plasma
A

Refractometry

27
Q

Lab Measurements: Total Protein

  • Deals with the migration of charged particles in an electric field based on:
    1. net electrical charge of the molecule (cations [+] migrate to the cathode [-], anions [-] migrate to the anode [+])
    2. size and shape of the protein (smaller = farther migration)
    3. electrical field strength, temperature, and medium properties
A

Electrophoresis

28
Q

Lab Measurements: Electrophoresis Dyes/Stains

These dyes are used for the electrophoresis of what chemical?
- Coomassie Brilliant Blue
- Ponceau S
- Amido Black

A

Serum

29
Q

Lab Measurements: Electrophoresis Dyes/Stains

These dyes are used for the electrophoresis of what chemical?
- Sudan Black
- Oil Red O

A

Lipoproteins

30
Q

Lab Measurements: Electrophoresis Dyes/Stains

These dyes are used for the electrophoresis of what chemical?
- Periodic Acid Schiff

A

Glycoproteins

31
Q

Lab Measurements

What analyte?
- Principle: Colorimetry (dye binding)
- An endpoint assay
- Determines the absorbance using spectrophotometry

A

Albumin

32
Q

Lab Measurements: Albumin Dyes

  • The most commonly used for albumin (it is sensitive)
  • It overestimates low levels of albumin
A

Bromcresol Green (BCG)

33
Q

Lab Measurements: Albumin Dyes

  • Most specific and most sensitive to albumin
A

Bromcresol Purple (BCP)

34
Q

Lab Measurements: Albumin Dyes

  • Not commonly used as it is not specific for albumin
A

Methyl Orange (MO)

35
Q

Lab Measurements: Albumin Dyes

  • Not commonly used as it has many interferences (bilirubin and salicylates)
A

Hydroxyazobenzene benzoic acid (HABA)

36
Q

Lab Measurements

How is globulin computed for?

A

Total Protein - Albumin = Globulin

37
Q

Lab Measurements: Albumin:Globulin Ratio

Determine the ratio (is globulin greater than or less than albumin?)
- cirrhosis
- multiple myeloma
- Waldenstrom’s macroglobulinemia

A

Globulin is GREATER than albumin (inverted ratio)

38
Q
  • This test is a rough measure of all the proteins in the plasma
  • Measurement reflects nutritional status, kidney disease, liver disease, and others
  • If abnormal, further tests must be performed to identify which protein fraction is abnormal so that specific diagnosis can be made
  • Hypoproteinemia vs. Hyperproteinemia
A

Total Protein

39
Q

Total Protein Abnormalities

  • An increase total plasma proteins, not an actual disease but as a result of underlying cause of dehydration
  • Dehydration - vomiting, diarrhea, excessive sweating, diabetic acidosis, and hypoaldosteronism
  • Absolute quantity remains unchanged, concentration is elevated due to decreased volume of solvent water
A

Hyperproteinemia

Note: It is not an actual disease because if you recall, an increased albumin level is not clinically significant (an increase in protein means an increase in albumin since it is the most abundant)

40
Q

Total Protein Abnormalities

Do these increase or decrease protein levels?
* Results in excessive production of γ globulins
* Some disorders are characterized by appearance of monoclonal protein or paraprotein in the serum and urine
* The most common disorder is multiple myeloma in which the neoplastic plasma cells proliferate in the bone marrow

A

Increased (these are the situations wherein hyperproteinemia is clinically significant)

Note: In multiple myeloma, TC and globulin is increased while albumin is normal

41
Q

Total Protein Abnormalities

  • Levels are less than the reference interval
  • Causes: excessive loss by excretion in the urine (renal disease), leakage (GIT), loss of blood in wounds, internal bleeding or extensive burns, decrease intake due to malnutrition or intestinal malabsorption
  • Occurs in conditions where a negative nitrogen balance exists (excessive breakdown of proteins)
  • Other causes: inadequate dietary intake, decreased synthesis due to liver disease, immunodeficiency disorders (a problem with the gamma-globulin, not albumin), accelerated catabolism of proteins (burns, trauma, or other injuries)
A

Hypoproteinemia

42
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Hepatic damage, cirrhosis, beta-gamma bridging, burns, trauma, and infection

A
  • Total Protein: Normal to Low
  • Albumin: Low
  • Globulin: Normal to High

Not affected by hepatic problems as they are produced by plasma cells

43
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Malabsorption, inadequate diet, and nephrotic syndrome

A
  • Total Protein: Low
  • Albumin: Low
  • Globulin: Normal
44
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Immunodeficiency Syndrome (e.g AIDS, HIV, undergoing chemotherapy, or immunodeficient)

A
  • Total Protein: Low
  • Albumin: Normal
  • Globulin: Low

Antibody production is affected

45
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Self-retention Syndrome

Secondary to renal disease

A
  • Total Protein: Low
  • Albumin: Low
  • Globulin: Low
46
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Dehydration

A
  • Total Protein: High
  • Albumin: High
  • Globulin: High

Leads to hyperproteinemia and hyperalbuminemia

47
Q

Protein Levels in Selected Diseases

Give the levels of the ff.:
- Total Protein
- Albumin
- Globulin

Diseases: Multiple myeloma and monoclonal and polycolinal gammopathies

A
  • Total Protein: High
  • Albumin: Normal
  • Globulin: High

Clinical Chemistry (CC 1) (22 decks)

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