Search PubMed⌕ Search

Biomedical subjects

V Bencko

Publications and source records attributed to V Bencko.

At least 91 records · Page 5Linked to original sources
PubMed1980

The effect of a milk diet on the retention of 74As labelled arsenic in mice.

The effect of 3 diets with different proportion of milk proteins on retention of arsenic was studied in mice. Arsenic was administered via drinking water in concentration 50 mg As [III] per litre labelled with 74As in amount 2.96 MBq per 100 ml. After 2, 4, 8, 16 and 32 days of exposure the mice in groups of 6 each from all 3 experimental cohorts were decapitated and the content of 74As was determined in whole body, blood, liver, kidneys, spleen, lungs and heart by measuring of the activity in Gamma Scintillation Counter Tesla. From the intake of drinking water and amount of arsenic found in the experimental animals was calculated retention of arsenic in mice at different exposure intervals in all three diets. The values of arsenic found at the exposure intervals in examined materials of all three experimental cohorts were compared. The results obtained indicate that a milk diet has no adverse effect at exposure to arsenic in the sense of enhancing of its retention in mice at given experimental conditions. The found data seemed to suggest that the milk protein rich diet caused retardation of the increase of arsenic concentrations in blood, liver and kidneys that might lead at a lower exposure rate to a decrease in arsenic content in tissues of exposed animals.

Animals↗
PubMed1980

Beryllium toxicity testing in the suspension culture of mouse fibroblasts.

Suspension culture of mouse fibroblast cell line L-A 115 was used to test beryllium toxicity in the presence of magnesium ions. Beryllium added to the MEM cultivation medium was bound in a complex with sulphosalicylic acid BeSSA complex, because the use of beryllium chloride turned out to yield ineffective beryllium phosphate that formed macroscopically detectable insoluble opacities. The BeSSA complex was used in the concentration range: 10(-3)--10(-9)M, magnesium was used in 3 concentrations: 10(-1)M, 5 x 10(-2)M and 10(-2)M. Growth curve analysis revealed pronounced beryllium toxicity at the concentration of 10(-3)M, magnesium-produced toxic changes were observed only at the concentration of 10(-1)M. No competition between the beryllium and magnesium ions was recorded. It is assumed that the possible beryllium-magnesium competition was significantly modified by the use of BeSSA complex-bound beryllium.

Animals↗
PubMed1980

Rate of malignant tumor mortality among coal burning power plant workers occupationally exposed to arsenic.

The mortality pattern was retrospectively analyzed among the workers of a power plant A (exposure group) combusting coal with high arsenic levels and among the workers of power plants B, C and D (control group), where arsenic concentrations in coal were by one order of magnitude lower. The exposed group consisted of 88 and the control group of 159 male subjects deceased over the period of the last 15--18 years. The rate of tumor mortality among the exposed subjects who died during their productive age was 38% (in the control group 23%), among those died after 60 it was 51% (in the controls 43%). This increase in the tumor mortality rates was not statistically significant. What was, however, statistically proved to be significant is the fact that malignancy-caused deaths in the exposed group occurred in younger age categories and after a statistically shorter exposure time (in both cases p < 0.05). Combusted coal is known to contain a variety of biologically active microelements, but the amount of arsenic alone (950--1500 g/1 tonne of coal) most probably fully justifies the suspected link between the tumor incidence and the overexposure to arsenic.

Adult↗
PubMed1980

Biliary excretion of 74As and its distribution in the golden hamster after administration of 74As (III) and 74As (V).

Biliary excretion of arsenic and its distribution in the organism were studied in golden hamsters after administration of Na3(74)AsO3 and Na2H74AsO4 solutions. Significant differences between the two valency forms of arsenic were found in the biliary excretion rate as well as in the cumulative biliary excretion of 74As. The arsenic biliary excretion after treatment with 74AS [III] [4.98 /+- 7.1, or 0.6 [0.2 - 1.1] percents of the administered dose] than that after 74As [V] application. On the other hand, arsenic excretion in the urine and stool were higher after the administration of pentavalent arsenic. The contents of 74As in the liver, kidneys, blood plasma and GIT wall were higher after the application of 74As [III]. It has been again confirmed tha compared to rats the hamster [similarly as the other laboratory animals] exhibits a significantly lower concentration of 74As in red blood cells [differences ranged by 2 orders of magnitude].

Animals↗
PubMed1979

Biliary excretion and distribution of 51Cr(III) and 51Cr(VI) in rats.

The biliary excretion and distribution of 51Cr after intravenous administration of 51Cr(III) (61CrCl5) or 51Cr(VI) (Na252CrO4 . 4 H2O) was studied in rats. The cumulative biliary excretion of 51Cr reached 24 hrs after the injection was significantly higher after administration of 51Cr(VI) than after 51Cr(III) 3.51+/-0.7% and 0.51+/-0.05% of administered dose, respectively). This difference was especially due to a higher rate of biliary excretion of 51Cr in the first hours after 51Cr(VI) administration. The excretion of 51Cr via faeces was also higher after administration of 51Cr(VI) (7.35+/-0.45%) OF ADMINISTERED DOSE, AS AGAINST 4.23+/-0.23% after 51Cr(III). On the other hand, no significant difference in urinary excretion of 51Cr was found. Statistically significant differences were also observed in the distribution of 51Cr in the organism after administration of both valence states of the metal.

Animals↗
PubMed1979

Penetration of beryllium through the placenta and its distribution in the mouse.

Penetration of beryllium through the placenta and its distribution in the organs after intravenous administration of BeCl2 in a dose of 0.1 mg/kg was studied in a series of experiments on ICR SPF mice. To trace the fate of beryllium, an isotope in the form of 7BeCl2 in an amount of 111kBq per animal was used. This dose was administered to a group of females before fertilization, on the 7th and 14th day of pregnancy, and to control animals. The animals were killed on the 18th to 19th day of pregnancy and the content of beryllium in the foetuses and its distribution in the organs of the mothers were determined by measuring activity. It has been found that beryllium penetrates through the placenta with difficulty, however, part of the dose administered circulated in the blood long enough for Be to penetrate the foetuses. Of interest is the finding that beryllium in the dose administered influenced the number of foetuses of the exposed females. This finding deserves detailed evaluation in the test of dominant lethal mutations.

Animals↗
PubMed1977

Effect of the combined action of selenium and arsenic on suspension culture of mice fibroblasts.

The protective influence of arsenic against the toxic action of selenium has been tested on suspension cultures of mice fibroblasts LA 115. The growth of the cells was observed after the isolated and combined action of sodium arsenite NaAsO2 and sodium selenite Na2SeO3. The concentration range of both substances in cultivation medium MEm (USOL) was 10(-5) -10(-11)M. The growth of treated cultures was analyzed daily during 5 days of exposure. From the results obtained, growth curves of the cell cultures were constructed and analyzed. The results of every determination were evaluated in relation to the corresponding control culture. The results obtained demonstrate that decreasing concentrations of arsenic enhanced its protective effect in the range of the concentrations used. In contrast, a low protective effect of selenium against arsenic was noted in the concentrations employed. The cell cultures have proved to be very suitable for toxicological studies of the combined effects of different substances.

Animals↗
PubMed1977

Carcinogenic, teratogenic, and mutagenic effects of arsenic.

This review outlines briefly the history and present status of the problem of carcinogenic, teratogenic and mutagenic effects of arsenic. Discrepancies between clinical observations and positive results of epidemiological studies and the experimental induction of cancer by arsenic are discussed. The present knowledge of the mechanism of teratogenic and mutagenic effects of arsenic is analyzed. The growing importance of arsenic as an environmental pollutant is demonstrated. Continuation of throughly organized epidemiological studies in regions with excessive arsenic exposure of the population and standardization of an epidemiological approach to this problem on an international basis are recommended. New approaches in experimental studies of the carcinogenicity of arsenic in combination with other known or suspected carcinogens are recommended as well.

Animals↗
PubMed1977

Test of environmental exposure to arsenic and hearing changes in exposed children.

Arsenic determination was carried out on hair, urine, and blood samples taken from groups of 10-year-old boys, each numbering 20 to 25 individuals, residing in a region polluted by arsenic. In all the examined materials considerably elevated concentrations of arsenic were found. The relation of the observed levels of arsenic to the distance of the place of residence up to a distance of more than 30 km from the source of the emissions was studied. On the basis of the results obtained, the most advantageous material for estimation of nonoccupational exposure to arsenic seems to be hair, in spite of some problems with the decontamination procedure involved. Considerable variability among individual arsenic values in the hair makes group examination a necessity. Hearing changes were analyzed in a group of 56 10-year old children residing near a power plant burning local coal of high arsenic content. The results of both audiometric and clinical examination were compared with those of control group numbering 51 children of the same age living outside the polluted area. The highly standardized audiometric and clinical examination were completed with a questionnaire analysis concerning the personal medical histories of the children. The obtained data were elaborated statistically by means of the chi(2)- test. In the case of air conduction, important hearing losses were found at frequencies of 125, 250 and 8000 Hz, especially at the lowest frequency range. Significant degrees of hearing loss were found in bone conduction as well as in the corresponding ranges of frequencies. The high statistical significance of the hearing impairments found points to very low probability of their being only an "accidental" finding. The possibility of toxic damage to the ear cannot yet be excluded.

Arsenic↗
PubMed1976

Biotransformation of As(III) to As(V) and arsenic tolerance.

The paper deals with excretion of As(III) and As(V) in the urine of mice exposed to a toxic concentration of As(III) (250 mg/1) in drinking water. After the exposures of 2, 6, and 8 days, the mice were given i.m. a solution of 74As(III) labeled sodium arsenite in a dose of 1.3 mg As(III)/kg b.w. and an activity of 3 muCi/l ml. After the sacrifice of the animal, the urine was drawn off directly from the bladder. The urine samples were subjected to separation of As(III) from As(V) by using a paper radiochromatography technique. The results showed that unexposed control mice excreted one-half of the administered As(III) in the form of As(V). Mice exposed to arsenic in drinking water exceted already, after 2 days of exposure, four-fifths of the applied As(III) in the form of As(V), after 4 days of exposure the proportion of As(V) was more than 95%, and after 8 days of exposure only traces of As(III) were present. The authors discussed the possibility of the biotransformation of As(III) to As(V) on arsenic tolerance.

Animals↗
PubMed1976

Mechanical damage to rabbit tracheal epithelium from inhaling inert pyrite dust of needle-like structure. Part II.

The ultrastructure of rabbit tracheal epithelium was studied 2, 8 and 26 hours after termination of 8-hour inhalation of ground pyrite dust. Pyrite particles persist in the cytoplasm of ciliated cells throughout the interval followed up. Only through degeneration and elimination of these cells from the epithelium is the inhaled dust gradually removed from the mucous membrane. Goblet cells discharge pyrite-containing mucus into the ciliary border region for a period of 26 hours after cessation of inhalation thus inducing further damage to the ciliary border and the apical regions of the cells even after termination of inhalation. The morphological appearance of the ciliary border, especially in the first phase after termination of inhalation, suggests a disturbance of the self-cleaning function of the eipithelium of respiratory passages. The inhalation of aerosol of needle-like structure causes mechanical damage to tracheal epithelium. Substantial retardation of the onset of epithelial regeneration and slow rate of elimination of the inhaled aerosol from the tracheal mucosa was noted.

Animals↗
PubMed1975

Biliary excretion of 7Be and its distribution after intravenous administration of 7BeCl2 in rats.

Wistar female rats were given two i.v. doses of 7BeCl2 (dose A = 0.025 mg Be2+/kg b.w.; dose B = 0.25 mg Be2+/kg b.w.). The rats were decapitated at 5, 24, and 48 hrs after administration. The kinetics of 7Be bile excretion during the 5 hrs after administration, as well as 7Be retention in selected organs and the urine and stool excretion of beryllium were investigated. Significant differences between the effect of both doses were found particularly in the shape of biliary excretion curves of 7Be. Unproportionally higher 7Be blood levels after a higher dose persisted for a longer period of time. The decrease of 7Be in blood after a higher dose between the 5th and 24th hr after the administration was accompanied by an increased content of 7Be in the liver and spleen as well as by an increased urine excretion. The results obtained tend to prove that the reticuloendothelial system mainly participated in beryllium retention. Urine represents the main excretion route of beryllium after a parenteral administration.

Animals↗
PubMed1975

Dehydrogenase activity of liver parenchyma in mice exposed to arsenic in drinking water.

The effect of arsenic administered in drinking water in the form of sodium arsenite in concentrations of 5,50 and 250 mg As-3+/1 on dehydrogenase activity (DHA) of liver parenchyma homogenate of exposed mice was studied. After an exposure lasting 2, 4, 8, 16, 32, and 64 days, 8--10 exposed mice and 5--10 animals of the control series were studied at each interval. DHA was determined by means of tetrazolium chloride reduction to formazan whose quantity was assessed spectrophotometrically after extraction with butanol. At a concentration of 5 mg A3+/1 a moderate increase in DHA was observed which was replaced by a moderate decrease at the following intervals. At a concentration of 250 mg A3+/1 a deep decrease in DHA (p smaller than 0.05) was recorded which did not return to values compararable with those of the control series in spite of its fluctuating increase in the course of exposure. At a concentration of 50 mg A3+/1 in drinking water ensuring the supply of doses which induce an increase in the tolerance to arsenic a decrease in DHA was found only at the first exposure interval. DHA is thus substantially less altered in comparison with the metabolic consumption of oxygen (MCO) under the same conditions. This finding signifies that MCO is a more sensitive indicator of arsenic exposure than DHA in the used arrangement of the experiment.

Animals↗