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G Trenta

Publications and source records attributed to G Trenta.

4 recordsLinked to original sources
PubMed1997

Peripheral blood lymphocyte decrease and micronucleus yields during radiotherapy.

PURPOSE: To investigate the relationship between lymphocyte decrease and cytogenetic response in individual patients undergoing radiotherapy. MATERIALS AND METHODS: Peripheral blood lymphocytes obtained from 35 patients with pelvic and from 14 with head and neck tumours before and during radiotherapy were PHA-stimulated in vitro and the cultures prepared for the cytokinesis-block micronucleus test. For some patients only, the micronucleus test was carried out after 2 Gy in vitro X-irradiation, and 3-aminobenzamide (2 mM) was used to calculate the 3AB-index. RESULTS: The initially observed individual variation in the decrease of lymphocytes disappeared with increasing number of radiation exposures, reaching a stable level at about 500/microl lymphocytes in the blood. The slope of the relationship between the reciprocal of the lymphocyte decrease ratio and equivalent dose indicates the radiosensitivity of the lymphocyte pool in individual patients. The micronucleus test performed on lymphocytes obtained from patients during radiotherapy (in vivo) provided a lower cytogenetic response than the in vitro micronucleus yield for the same dose, so it was possible to calculate the cytogenetic recovery factor k. A correlation was found between the 3AB-index calculated before radiotherapy, and the recovery factor k. CONCLUSIONS: The 3AB-index, the micronucleus frequency after 2 Gy in vitro X-irradiation, and the cytogenetic recovery factor are proposed as predictive of individual response to radiotherapy.

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[Possibilities and limitations of the predictive risk estimates and epidemiological studies following the Chernobyl incident].

The disastrous accident at the nuclear power station at the Chernobyl on 1986 (April 26) has brought attention to the estimation of radiation health effects and many "experts" were attending to the evaluation on oncogenic mortality increase among the Italian population in the next future. On the contrary at that time too few peoples were worried about the possibility of detecting such an increase. Discussion of this topic is notoriously fraught with difficulties arising from differences of opinion how to estimate low-dose risk in humans without data from direct observation. One opinion is to extrapolate from the data points obtained at relatively high doses toward zero dose (zero extrapolation theory). This permit estimates of risk to be made but, in the final analysis, no data from humans exist that show that low-level radiation exposures produce measurable biologic effects. For that this theory is more useful in radio-protection and medico-legal subjects. It is easy on a statistical basis to prove the impossibility to establish an increase in human cancer after low doses of ionizing radiation such as those received environmentally after the Chernobyl's accident. In this condition to observe the numbers of radiation-induced cancer deaths that far exceed the "natural" incidence would require a follow-up a sample more and more greater than the italian population herself. Indeed the statistical power of a hypothetical follow-up study at a suitable confidence level would require a sample size higher than a milliard of persons for the detection of an increase of a generic cancer mortality and higher then seven hundred of millions for the detection of an increase of the specific thyroid cancer mortality. In more detail the following figures for the parameters needed to curring out the evaluation have been used: medium dose equivalent to the thyroid, 2.03 mSv; medium effective dose equivalent up to december '87, 0.6 mSv; thyroid cancer mortality in the italian population, 0.94 10(-5) y-1; total cancer mortality in the italian population, 22.2 10(-2) y-1; risk factor per unit dose equivalent in thyroid, 0.5 10(-6) mSv-1; risk factor per unit effective dose equivalent, 2.0 10(-5) mSv-1. Applying the foregoing values in statistical inference methods it could be achieved that 7.5 18(8) and 1.25 10(9) persons must be followed-up in the next 30 years to detect a significant increase over the "natural" cancer mortality for thyroid and "total body" radioinduced cancers respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

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