Complete culture medium is better than low folate medium for detecting increased chromosome aberrations in smokers in 48-h lymphocyte cultures

Expression of common fragile sites in untreated non-Hodgkin's lymphoma with aphidicolin and folate deficiency

The frequency and distribution of aphidicolin induced and folate sensitive common fragile sites on chromosomes of peripheral blood lymphocytes in untreated non-Hodgkin's lymphoma patients and healthy controls showed a considerable overlap in the expression of common fragile sites between the two groups. However, a significant increase in the expression of 16 aphidicolin induced common fragile sites was seen in untreated lymphoma patients. In the folate deficient cultures only, the common fragile sites 2q22, 8q24, 11q13, 12q21, 16q22, 17p12 and 20p12 were found in both the groups under study. The fragile sites at 8q22, 8q24, 11q13 and 18q21 in patients showed an increased expression over the control group. Interestingly these fragile sites were located in the same chromosomal bands as the oncogenes, MOS, MYC, BCL-1 and BCL-2 as well as cancer breakpoints specifically associated with non-Hodgkin's lymphoma, suggesting the possibility that fragile sites may play a critical role in the pathogenesis of non-Hodgkin's lymphoma.

International Commission for Protection Against Environmental Mutagens and Carcinogens. Deoxyribonucleoside triphosphate levels: a critical factor in the maintenance of genetic stability

DNA precursor pool imbalances can elicit a variety of genetic effects and modulate the genotoxicity of certain DNA-damaging agents. These and other observations indicate that the control of DNA precursor concentrations is essential for the maintenance of genetic stability, and suggest that factors which offset this control may contribute to environmental mutagenesis and carcinogenesis. In this article, we review the biochemical and genetic mechanisms responsible for regulating the production and relative amounts of intracellular DNA precursors, describe the many outcomes of perturbations in DNA precursor levels, and discuss implications of such imbalances for sensitivity to DNA-damaging agents, population monitoring, and human diseases.

Effects of diet and folate on levels of micronucleated polychromatic erythrocytes

We describe a study examining the effects of fried beef consumption on the frequency of micronuclei in RNA-positive polychromatic erythrocytes (PCEs) in humans. 5 splenectomized individuals participated in a 2-week experiment consisting of 3 phases. During the first and last phases the subjects refrained from eating cooked meat for 4-5 days. This was designed to clear their system of mutagens found in cooked-meat products. In the second phase each person ate a similar diet, but also consumed 4 quarter-pound well-done hamburgers per day for 4 days. Erythrocyte-folate levels were also measured for each donor. No association between diet phase and micronucleus frequencies was observed among the 2 subjects with normal levels of folate. However, among the 3 low-folate donors, the frequency of micronucleated PCEs appeared to be associated with diet. Micronucleus frequencies began to increase 1 day following onset of the beef phase, and started to decline 1 day after finishing this phase. These observations are in agreement with erythrocyte maturation kinetics following short-term exposure. A repeat study performed on one of the low-folate donors consisted of two beef phases separated by a vegetarian phase. Beef in one phase was fried (high in mutagenic amino-imidazoazaarenes [AIAs]) while the beef in the other phase was fried after first being microwave-cooked (low in AIAs). Significant increases in the micronucleus frequency were not observed in this experiment, suggesting that AIAs formed during frying were not solely responsible for the induction of micronuclei.

The in vivo micronucleus test in human capillary blood lymphocytes: methodological studies and effect of ageing

The in vivo micronucleus test in lymphocytes of human capillary blood collected by skin puncture is described. This method needs only 1-2 drops of finger blood. The normal value of micronucleus frequencies in lymphocytes from 250 healthy persons aged 6-88 years was determined. The upper limits of normal values were estimated by means of percentile. The 95th percentiles were 1/1000 and 1.5/1000 for the 6-45-year age group and the 46-88-year age group, respectively. There was no significant difference in micronucleus frequency between men and women. On the basis of micronucleus assays in more than 3000 cases, we consider that the micronucleus test in human capillary blood lymphocytes is a rapid, convenient and sensitive procedure for monitoring a human population exposed to environmental and occupational mutagens and carcinogens.