Hemoglobin Adduct Biomarkers

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Hemoglobin Adduct Biomarkers

• Cindy Changoor cindy.changoor_at_utoronto.ca
• Hayley Fleming hayley.fleming_at_utoronto.ca
• Sarah Luong sarah.luong_at_utoronto.ca
• Ruby Mehta ruby.mehta_at_utoronto.ca

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Biomarkers

• Classic Biomarkers Chemicals and their
  metabolites in blood and urine and modified
  enzymes
• Hemoglobin Adducts new biomarkers thought to be
  useful for estimating measurements of chemical
  exposure

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Why are they used?

• To measure and monitor carcinogens, most commonly
  chemical carcinogen exposure
• A method to estimate the dose of exposure to
  these chemical carcinogens and to determine
  effects in different stages of disease
  progression

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How are they used?

• N-Alkyl Edman Method
• Determines adducts formed
• at the amine group of the
• N-terminal valine of hemoglobin
• Modified Edman degradation method
• Quantitative analysis determined by GC-MS or
  LC-MS

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Analysis
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Advantages Disadvantages

• Advantages
• More useful biomarker of exposure than urinary
  metabolites for many chemicals
• More useful than DNA biomarkers for dose
  monitoring
• Disadvantages
• Most common method
• can only detect one adduct per globin chain

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Relevance to Pharmacy

• A good way to measure chemical carcinogens in
  patients
• Can help with early diagnosis and treatment
• Smoking repercussion
• Mohamadi Sarkar et al., CYP1A2 and NAT2
  phenotyping and 3-aminobiphenyl 4-aminobiphenyl
  hemoglobin adduct levels in smokers and
  non-smokers

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Results

• The levels of 4-ABP Hb adducts were significantly
  greater in smokers than non-smokers, the ratio
  being 51
• The regression model developed with CYP1A2 and
  NAT2 phenotype and number of cigarettes smoked
  accounted for 47 of the variability in 3-ABP
  adducts and 32 variability in 4-ABP adducts

Meyer, M. J., Bechtold, W. E. (1996) Protein
Adduct Biomarkers State of the Art.
Environmental Health Perspectives, 104 Suppl
5879-82.
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Future of Biomarkers

• Money is continuing to be invested in biomarker
  investigations
• The search for biomarkers has been slow due to
  extensive research studies

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Summary

• Hemoglobin adducts are more useful biomarkers
  than urinary metabolites for determining the dose
  of exposure to many chemical carcinogens.
• Hemoglobin adducts can show the accumlated effect
  of the previous 3 months exposure because the
  adducts depend on the lifespan of the
  erythrocyte.
• A modified Edman degradation method, called the
  N-Alkyl Edman method, is commonly used to isolate
  adducts formed at the amine group of the
  N-terminal valine of hemoglobin for further
  analysis
• GC-MS or LC-MS are used to analyze the protein
  samples quantitatively in order to find the
  concentration of adducts present
• These analyses have indicated that the
  concentration of adducts in blood protein, such
  as hemoglobin, is directly proportional to the
  amount of carcinogenic exposure
• Hemoglobin biomarkers are more useful than
  urinary markers and DNA, but are limited by the
  fact that they can only detect one adduct per
  globin chain.
• We are able to measure the chemical carcinogen
  exposure in patients which can lead to efficient
  monitoring and quick diagnosis.
• One study using hemoglobin adducts looked at
  different levels of 3-aminobiphenyl and
  4-aminobiphenyl (both carcinogens) levels in
  smokers and non-smokers and found that the levels
  of 4-aminobiphenyl were significantly greater in
  smokers than non-smokers.
• Money is continually being invested in this field
  however the process is slow due to large
  population based studies that need to be done to
  ensure that biomarkers actually reflect a disease
  process and not due to measurement errors or
  other incidental variations.

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References

• Meyer, M. J., Bechtold, W. E. (1996) Protein
  Adduct Biomarkers State of the Art.
  Environmental Health Perspectives, 104 Suppl
  5879-82.
• Moll, T., Harms, A., and Elfarra, A. 2000. A
  Comprehensive Structural Analysis of Hemoglobin
  Adducts Formed after in Vitro Exposure of
  Erythrocytes to Butadiene Monoxide. Chem. Res.
  Toxicol.. 13, 11, 1103 1113.
• Ogawa, M., Oyama, T., Isse, T., Yamaguchi, T.,
  Murkami, T., Endo, Y., Kawamoto, T. 2006.
  Hemoglobin Adducts as a Marker of Exposure to
  Chemical Substances, Especially PRTR Class I
  Designated Chemical Substances. Journal of
  Occupational Health, 48, 314-328.
• Sarkar, M., Stabbert, R., Oey, J., Rustemeier,
  K., von Holt, K., Schepers, G., Roethig, H.
  CYP1A2 and NAT2 phenotyping and 3-aminobiphenyl
  and 4-aminobiphenyl hemoglobin adduct levels in
  smokers and non-smokers. Toxicology and Applied
  Pharmacology. vol.213,no.3,198-206.

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Questions?
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