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Your search keyword '"Riches AC"' showing total 3 results
Start Over Author "Riches AC" Journal international journal of radiation biology
3 results on '"Riches AC"'

1. The G2 chromosomal radiosensitivity assay.

Author

Bryant PE, Gray L, Riches AC, Steel CM, Finnon P, Howe O, Kesterton I, Vral A, Curwen GB, Smart V, Tawn EJ, and Whitehouse CA

Subjects
Carcinogenicity Tests, Chromosomes, Human genetics, DNA Damage, G2 Phase genetics, Humans, In Vitro Techniques, Lymphocytes radiation effects, Chromosomes, Human radiation effects, G2 Phase radiation effects, Radiation Tolerance
Abstract

Although requiring stringent experimental conditions to achieve good reproducibility, the G2 assay has potential as a sensitive marker for cancer susceptibility, and is particularly useful in population studies. Immediate culture of blood is preferable, but overnight storage of blood either at ambient temperature or at 4 degrees C does not appear significantly to affect G2 scores. Transport of blood may lead to additional variability in assay results and should be well controlled. Although reproducibility is generally good, G2 scores on blood from certain individuals appear to show significant variability in repeat samples. Thus, determination of an individual's radiosensitivity may require multiple assays on different occasions. While it is recognized that the distinction between aligned and mis-aligned discontinuities has no scientific basis, some laboratories have decided for the purpose of record-keeping to score all aligned discontinuities as gaps, and mis-aligned discontinuities as breaks. In all cases the final G2 score should comprise the sum of all gaps and breaks.

Published
2002
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2. Radiation-induced transformation of SV40-immortalized human thyroid epithelial cells by single exposure to plutonium alpha-particles in vitro.

Author

Riches AC, Herceg Z, Bryant PE, Stevens DL, and Goodhead DT

Subjects
Animals, Cell Line, Humans, Mice, Mice, Nude, Plutonium, Simian virus 40, Thyroid Neoplasms etiology, Alpha Particles, Cell Transformation, Neoplastic radiation effects, Thyroid Gland radiation effects
Abstract

Human thyroid carcinomas have been induced following exposure of SV40-immortalized human thyroid epithelial cells in vitro to single doses (0.14 Gy to 1.57 Gy) of 3.26 MeV alpha-particles from a plutonium 238 source. Tumours were detected between 50 and 160 days following subcutaneous transplantation of the irradiated cells in athymic mice. No tumours were observed following transplantation of unirradiated cells. The relative biological effectiveness (RBE) of the alpha-particles, estimated from cell survival curves, was 4.8 at 50% survival and 3.3 at 5% survival. A first estimate of the RBE at peak tumour induction was 3.8. This system provides a means of studying the mechanisms of tumourigenesis in human thyroid epithelial cells induced by ionizing radiations, including tumours induced by single alpha particles such as from environmental natural radon and polonium and artificial plutonium and americium, and those induced by beta- or Auger-emissions from particular iodine isotopes.

Published
1997
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3. Radiation-induced transformation of SV40-immortalized human thyroid epithelial cells by single and fractionated exposure to gamma-irradiation in vitro.

Author

Riches AC, Herceg Z, Bryant PE, and Wynford-Thomas D

Subjects
Animals, Cell Line, Cell Transplantation, Epithelial Cells, Epithelium radiation effects, Humans, Mice, Mice, Nude, Radiation Dosage, Simian virus 40 genetics, Thyroid Gland cytology, Transfection, Cell Transformation, Neoplastic radiation effects, Gamma Rays, Keratinocytes radiation effects
Abstract

Radiation-induced transformation of a human thyroid epithelial cell line (HTori-3) has been investigated following exposure to single and fractionated doses of gamma-irradiation. The human epithelial cells were irradiated in vitro and following passaging, transplanted to the athymic nude mouse. Following a single exposure to gamma-irradiation in the range 0.5-4 Gy, 22 tumours were observed in 45 recipients and following three equal fractions in the range 0.5-4 Gy per fraction, 18 tumours were observed in 31 recipients. Tumours were undifferentiated carcinomas and were observed from 7 to 20 weeks after transplantation. They occurred after similar radiation doses to those received by the children in the Belarus region of Ukraine, who developed thyroid tumours. The number of tumours observed, in each group receiving cells irradiated with a single dose of gamma-irradiation in the range 0.5-4 Gy, was similar. Cell lines were established from some tumours and the tumorigenicity confirmed by retransplantation. These tumour cell lines were more radiosensitive than the human thyroid epithelial cell line they were derived from. This indicates that transformed cells were not being selected from a subpopulation within the parent cell line but that radiation-induced transformants were being induced de novo. The human origin of the tumours was established by karyotyping, immunocytochemical demonstration of human epithelial cytokeratins and p53 analysis. DNA fingerprinting confirmed that the tumours were derived from the original cell line. Human epithelial cells have proved difficult to transform by exposure to radiation. This human thyroid epithelial cell line can be transformed by single and fractionated doses of gamma-irradiation and promises to be a useful model for studying the mechanisms of radiation-induced transformation of human epithelial cells.

Published
1994

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