PMID: 8609457Feb 1, 1996Paper

Influence of melanin on pO2 measurement in vitro and in vivo

International Journal of Radiation Biology
C D Thomas, M Guichard

Abstract

In a previous study an apparent discrepancy was found between the radiobiological hypoxic fraction of tumours and the tumour oxygenation: the lowest percentage of low pO2 values was observed in the most hypoxic tumour, a heavily pigmented melanoma Na11+. This report describes a similar study with two other less pigmented melanomas. The influence of melanin on pO2 readings was also studied using synthetic melanin and L-tyrosine. Tumour oxygenation was measured using the KIMOC 6650 histograph, apparent pO2 was also measured in the calibration chamber in a buffer containing melanin or L-Tyr at three pHs (6.5, 7.0, 7.5) and bubbled with three different oxygen concentrations (0.2, 2.0, 20.9%). The proportion of hypoxic cells, measured by an in vivo/in vitro colony assay, was 58% for Na11+, 30% for Be11 and 51% for Ma11 tumours. The melanin content (microgram/10(6) cells) was 6.5 (Na11+), 2.0 (Be11), and 4.3 (Ma11). The percentages of radiobiologically hypoxic cells and low pO2 reading values (<2 mmHg) were inversely correlated, contrary to what was expected. In buffer, the pO2 values increased significantly with the melanin concentration: the lower the oxygen concentration, the greater was the increase in pO2. The pO2 readings value...Continue Reading

References

Jun 1, 1977·Journal of the National Cancer Institute·M GuichardE P Malaise
Oct 1, 1991·Experimental Cell Research·J BustamanteA Boveris
Oct 1, 1990·International Journal of Radiation Oncology, Biology, Physics·F KallinowskiP Vaupel
Apr 1, 1989·International Journal of Radiation Oncology, Biology, Physics·F LespinasseM Guichard
Mar 1, 1994·International Journal of Radiation Biology·L M MartinM Guichard

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