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Biomedical subjects

B Smyk

Publications and source records attributed to B Smyk.

16 recordsLinked to original sources
PubMed1998

Spectroscopic manifestations of flavomononucleotide dimers in polyvinyl alcohol films.

Absorption and fluorescence spectra of flavomononucleotide (FMN) in polyvinyl alcohol films (PVA) over a very wide concentration range are investigated. The dimerization constant as well as the pure monomer and dimer spectra are calculated and the structural parameters of FMN dimer are established. Excitation wavelength and temperature dependencies of FMN/PVA fluorescence spectra for different FMN concentrations were carried out. These measurements together with those of absorption reveal that dimers are imperfect traps for excitation energy and that the energy transfer can occur both in forward and in reverse direction. Moreover, it was shown that the observed temperature changes in fluorescence spectra may be qualitatively explained by the effect of inhomogeneous broadening of FMN energy levels and by the presence of fluorescent dimers.

Dimerization↗
PubMed1976

Effect of dicumarol on the growth of some soil microorganisms.

The effect of dicumarol on growth of selected soil bacteria: Azotobacter chroococcum, Arthrobacter globiformis, A. citreus and Bacillus megaterium was studied. The following minimum concentrations were inhibitory in vitro: Arthrobacter citreus--20 mug/ml., Bacillus megaterium--40 mug/ml., Azotobacter chroococcum--40 mug/ml. Arthrobacter globiformis--70 mug/ml. Cells of all microorganisms studied grown in the presence of dicumarol developed aberrant morphological forms.

Arthrobacter↗
PubMedDate not supplied

Selenium effect on the growth of carcinogenic fungi and cytotoxic action of aflatoxin B1 on lymphocyte culture and on embryonal development of Xenopus laevis.

The authors report the results of investigations on the protective effect of selenium against teratogenic and cytotoxic action of aflatoxin B1 and the inhibitory action of this element on the growth of fungi producing carcinogenic aflatoxins. Sodium selenate inhibited the growth of cultures of such fungi belonging to the class Fungi imperfecti as Aspergillus flavus, Aspergillus fumigatus, Penicillium meleagrinum and Penicillium rougolosum. Added to cell cultures of lymphocytes sodium selenate inhibited the cytotoxic action of aflatoxin B1 evidenced by inhibition of PHA-stimulated blastic transformation of these cells and reduction in the number of mitoses. Sodium selenate added to the medium in the culture of Xenopus laevis larvae poisoned with aflatoxin B1 reduced significantly the early mortality of embryos and counteracted the teratogenic action of aflatoxin B1. This action was observed, however, only in early phase of morulation. The authors discuss the importance of their observations for the studies on the role of bioelements deficiency in the environment for induction of malignant transformation.

Aflatoxins↗
PubMedDate not supplied

Environmental risk factors of cancer and their primary prevention.

The evaluation of the influence of different environmental carcinogenic factors requires interdisciplinary cooperation. Related studies include epidemiological surveys and air, water and soil, chemical, toxicological, and microbiological analyses, supplemented by experimental verification of suspected ecological pathogens and cofactors. A balance of carcinogens and protective agents in the external environment and in the human body is recommended for an ecologically oriented prevention. Toxicological control of the food chain using modern technology (Proton-induced X-ray emission (PIXE), nuclear activation analysis, and induced coupled plasma) should be integrated with microanalyses at the cellular level (by X-ray scanning electron microscopy, nuclear magnetic response, PIXE, and spontaneous and delayed chemiluminescence for balance of free-radicals and their scavengers). A pilot cross-disciplinary study conducted in the area of a "cluster" of human neoplasms and cattle leukemia, in comparison with control villages in Poland, showed an excess in Pb, Hg, Ni, Rb, K, Mn, Cr, and Zn, accompanied by a nutritional deficiency in Mg, Ca, Fe, Co, and Se in the food chain of the "cluster." The living and breeding houses in this area were significantly more contaminated with the toxicogenic molds Aspergillus flavus and Penicillium meleagrinum and by nitrate and nitrite in the drinking water. Our experiments showed that selenium deficiency stimulated the growth of fungi and some bacteria and increased the immunosuppressive and teratogenic effects of aflatoxin B1. New methods of protection of the indoor environment against microbiological contamination and laser-related biotechnology for nutritional prevention of selenium deficiency and associated risk of neoplasms have been introduced. Primary prevention requires a large scale application of highly sensitive methods for early detection of risk factors in the environment, food, water, and at the personal level, as well as education of the society and an integrated common corrective action.

Air Pollution↗