Demetrios P. Matthopoulos

Effect of 910-MHz Electromagnetic Field on Rat Bone Marrow

Aiming to investigate the possibility of electromagnetic fields (EMF) developed by nonionizing radiation to be a noxious agent capable of inducing genotoxicity to humans, in the current study we have investigated the effect of 910-MHz EMF in rat bone marrow. Rats were exposed daily for 2 h over a period of 30 consecutive days. Studying bone marrow smears from EMF-exposed and sham-exposed animals, we observed an almost threefold increase of micronuclei (MN) in polychromatic erythrocytes (PCEs) after EMF exposure. An induction of MN was also observed in polymorphonuclear cells. The induction of MN in female rats was less than that in male rats. The results indicate that 910-MHz EMF could be considered as a noxious agent capable of producing genotoxic effects.

Pesticide exposure and genotoxicity correlations within a Greek farmers' group

Humans are exposed to pesticides as a consequence of their use in fields or persistence in a variety of media, including air, water, soil, plants, and animals. The use of pesticides, to which humans are exposed, will possibly increase in the near future. This exposure has been related to several human diseases, including cancer. In the present study, we investigated whether occupational exposure to a complex mixture of pesticides is resulting in increased micronuclei (MN) frequency in peripheral blood lymphocytes. Exposed and control subjects were selected in southern Crete, where intensive use of pesticides is observed. Statistically significant differences in micronuclei frequencies in the studied groups were revealed from the obtained results. Comparison of MN frequencies on control and exposed subjects between smokers and non-smokers did not reveal any statistically significant differences. Further studies in other areas in Greece, enlarging the sample size and covering other farmer groups with different farming activities and levels of exposure, are needed to generalize the findings of this study.

The effect of gamma irradiation on collagen fibril structure

Abstract The structure of mouse skin collagen fibrils treated with 500 rad gamma irradiation was studied by electron microscopy. Examination of specimens after 1, 4 and 8 weeks of treatment revealed collagen fibrils consistently larger in diameter than those from normal specimens with the majority of irradiated fibrils measuring 110–138 nm, as opposed to 62–84 nm in the control. No marked differences in cross-linking were detected between irradiated and control reconstituted type I or type III collagen, either by polyacrylamide gel electrophoresis or by thermal stability measurements.

Environmental news in Greece : evaluation of the way newspapers deal with environmental issues

This article examines the question of newspaper journalists’ education in environmental matters, the role of the newspapers as an informal means of environmental education, and the approach of provincial and national newspapers in Greece, noting deficiencies. The minor contribution of scientists to newspaper articles is highlighted.

Evaluation of genetic damage in tobacco-growing farmers occupationally exposed to a mixture of metalaxyl and imidacloprid

The use of pesticides, to which humans are exposed, will possibly be increased in the near future. Exposure occurs via inhalation or skin contact during the preparation of the solutions to be sprayed or during spraying. The aim of this study was to evaluate the potent genetic damage in tobacco-growing farmers occupationally exposed to a mixture of metalaxyl and imidacloprid before and after spraying. This evaluation was performed by the micronucleus assay. The results obtained show that there are no statistically significant differences in the micronuclei frequencies of our studied groups before and after spraying. Analysis on the basis of smokers versus non-smokers did not show statistically significant differences. Analysis between control and exposed farmers revealed a significant difference in the smoking group after exposure to these pesticides. Further studies are required in order to estimate the potential effects of pesticides.

Tissue culture fixation with diimidoesters—I. comparison of structure obtained with diimidoesters and formaldehyde

Abstract The effects of the fixatives dimethyladipimidate (DMA) and dimethylsuberimidate (DMS) on tissue culture were studied using African green monkey kidney cells, CV1, and their SV40 transformant COS1. To determine the best conditions for preserving cellular structure with these reagents, the cells were examined either in phase contrast microscope or in light microscope after haemotoxylin/eosin staining. With this method, the most satisfactory conditions were those employing 0.25 M Tris pH 8.0 and diimidoesters (DMA or DMS) at a concentration of 15 mg/ml. Morphologically, diimidoester-fixed and formaldehyde-fixed cells were similar except that with the diimidoesters the nuclei exhibit a granular thread-like structure with apparent granular nucleolei too. Furthermore, the DMA- or DMS-fixed cells gave better identifiable mitotic pictures than the formaldehyde-fixed cells. Using specific fluorescent antibodies against SV40 large T-antigen, it was found that the association with the plasma membrane was more readiky seen in DMS-fixed transformed cells than in formaldehyde or acetone/methanol-fixed cells.

Morphological alterations caused by lithium in various cell lines

Lithium is being used for the treatment of mental diseases and for the attenuation of muelosuppression during chemotherapy. As during long term lithium treatment kidney damage has been reported, we studied morphological alterations in cells of kidney origin after exposure to lithium chloride. Above the level of 4 mmol, lithium has fatal effects in CV1 cells while HeLa cells that are not originating from kidneys, tolerate higher lithium concentrations. Cellular morphology alters during treatment duration. At early stages, cells become flatter on their substrate and upon longer than 4 days treatment begin to detach from their substrate and eventually cell death comes in a concentration dependent manner. The only morphological alteration observed in a lymphoblastoid cell line was a statistically significant cellular swelling.

Tissue culture fixation with diimidoesters—II. The development of the vimentin type filament network of monkey kidney CV1 cells

Abstract The development of the vimentin-type intermediate filament network of dimethylapimidate (DMA)- and dimethylsuberimidate (DMS)-fixed monkey kidney CV1 cells was studied using the indirect immunofluorescent method. Morphologically, diimidoester (DMA or DMS)-fixed cells revealed a more complexed vimentin network than formaldehyde-fixed ones. In spite of this complexity, the clarity of individual filaments in DMA- or DMS-fixed cells was remarkable even in the most complex areas. Other evidence suggests that the buffer system of the diimidoester solutions plays a role in the clarity of the obtained immunofluorescent pictures.

Differential heat shock gene expression in chick blastula

SummaryThe component areas of chick blastula show differential expression of heat shock genes. The area opaca (ao), marginal zone (mz) and central area (ca) components of the epiblast display distinct quantitative and minor qualitative differences in the heat-induced and heat-repressible proteins, but are clearly different from the primary hypoblast (endoderm) in their expression of a given stress protein (hsp) as a response to heat shock. The major proteins synthesized in the component areas of epiblast in response to heat shock include hsp 18, 24, 70 and 89 Kd. Two-dimensional electrophoresis shows that each of these proteins consists of multiple charged species. The hypoblast expresses only hsp 70 Kd at non-significant levels and shows marked inhibition in the level of synthesis of heat-shock-repressible proteins. Heat shock during the blastula stage results in an increase in the size of the blastoderm and disrupts normal embryonic development. The heat shock genes provide an important molecular marker, which attests to regional specification in the chick blastula.

Induction of the primitive streak in the chick blastoderm embryo: patterns of protein synthesis

SummaryInduction of the primitive streak is correlated with specific qualitative and quantitative changes in protein synthesis in the component areas of chick blastoderm. Blastoderm embryos at the initial to intermediate primitive streak stage were labeled with L-[35S] methionine. Radioactively labeled proteins separated by two-dimensional sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis revealed differences in the number and density of spots among the component areas of the epiblast and hypoblast. Protein patterns of the area opaca, marginal zone and central area of the epiblast are very similar qualitatively but show distinct quantitative differences. A comparison between any of the component areas of the epiblast and the hypoblast in chick blastoderm embryos, however, reveals both qualitative and quantitative differences. A protein with a molecular weight of 30,000 unique to the component areas of the epiblast, and proteins with a molecular weight of 22,000 and 37,000 unique to the hypoblast are prominent and seem to be related to the initial appearance of the primitive streak.