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Biomedical subjects

M Cikrt

Publications and source records attributed to M Cikrt.

At least 19 recordsLinked to original sources

Mobilization of mercury by DMPS in occupationally exposed workers and in model experiments on rats: evaluation of body burden.

The aim of the study was to evaluate the efficacy of DMPS (sodium-2,3-dimercapto-1-propane sulfonate) (Dimaval) administration for mobilizing mercury from the body in occupationally exposed people and experimental animals. Two doses of DMPS were administered at a 24-h interval to: (a) groups of people occupationally exposed to merkury--workers of the chloralkali industry (n = 43), and dentists (n = 12), (b) non-exposed individuals (n = 20), and (c) rats chronically exposed to mercury vapour at the concentration of 0.8 mg/m3 Hg degree (6 h/day, 5 days/week) for 15 weeks. In an out-patient mobilizing test, the urinary excretion of mercury 48 h after the administration of the first dose reached 1513 micrograms in the group of industrial workers, 132.6 micrograms in dentists, and 3.78 micrograms in controls. In rats, two consecutive doses of DMPS decreased kidney content of mercury by about 30% and 50% after oral and intraperitoneal administration, respectively. Kidney mercury burden was calculated on the basis of the data from animal and human studies of the mobilization of mercury via urine after DMPS treatment: 61, 2800 and 28,000 ng/g in controls, dentists and workers, respectively. It was estimated that two doses of DMPS mobilized 17-20% (after oral administration) and 25-30% (after intramuscular administration) of kidney mercury burden, both in the control and exposed subjects.

Adult↗

The Czech National Registry of Occupational Diseases. Ten years of existence.

The Czech National Registry of Occupational Diseases was founded in 1991 with the intention of restoring the information system on occupational diseases, which had collapsed in 1990, following deep societal changes brought about by the revolution in 1989. During the ten years of its existence, the Czech National Registry of Occupational Diseases proved to be a reliable information system providing valid data on occupational diseases. The completeness and quality of data stored in the Registry are being controlled by trained personnel. The information is available on-line for competent authorities. This makes it possible to monitor the situation regarding the incidence and the structure of occupational diseases, and to signal arising problems so that effective preventive measures can be taken immediately. Currently, the Registry contains information on approximately 30,000 cases of occupational diseases. A decreasing trend of yearly reported occupational diseases is evident. This fact must be interpreted cautiously. It may reflect the decreasing number of persons working at occupational risk and/or the improvement of hygienic situation at workplaces. However, in addition to these positive changes, the underreporting of occupational diseases in the Czech Republic is highly probable. Workers with an occupational disease feel handicapped at the labor market and seek to avoid the label. Furthermore, effectiveness of the Czech occupational health care system, which is still in the period of restructuring, is far from being perfect.

Czech Republic↗

Neurological and electrophysiological examinations on three groups of workers with different levels of exposure to mercury vapors.

The authors performed neurological, visual evoked potentials (VEP) and electroneurography (ENG) examinations on three groups of workers with occupational exposure to mercury vapors (Hg(0)), and on a control group. The exposure of dental professionals (n = 36) was mild, that of chloralkali plant workers (n = 36) was intermediate, and that of workers from mercury works (n = 77) was very high. Symptoms and signs of micromercurialism were observed only in the group with the highest exposure to Hg(0). In comparison with the control group, a shortening of VEP latency and a decrease in amplitude were found in the exposed groups. The VEP changes correlated with Hg(0) excreted in urine after administration of a chelating agent - sodium 2,3-dimercapto-1-propan sulfonate (DMPS). The frequency of abnormal VEP results increased with increasing levels of exposure. ENG changes were observed only in the group with the highest exposure to Hg(0). An isolated decrease of sural nerve conduction velocity was observed in 18% of total workers. In 70% of the cases, this was associated with an abnormality in VEP. The combination of a decrease in sural nerve conduction velocity and an abnormality of VEP seems to be a characteristic pattern of electrophysiological changes in persons exposed to mercury vapors.

Adult↗

Hazardous wastes in eastern and central Europe: technology and health effects.

Issues of hazardous waste management are major concerns in the countries of eastern and central Europe. A National Institute of Environmental Health Sciences-supported conference was held in Prague, Czech Republic, as a part of a continuing effort to provide information and promote discussion among the countries of eastern and central Europe on issues related to hazardous wastes. The focus was on incineration as a means of disposal of hazardous wastes, with discussions on both engineering methods for safe incineration, and possible human health effects from incineration by-products. Representatives from government agencies, academic institutions, and local industries from 14 countries in the region participated along with a few U.S. and western European experts in this field. A series of 12 country reports documented national issues relating to the environment, with a focus on use of incineration for hazardous waste disposal. A particularly valuable contribution was made by junior scientists from the region, who described results of environmental issues in their countries.

Environmental Health↗

Biliary iron excretion in rats following treatment with analogs of pyridoxal isonicotinoyl hydrazone.

Iron overload is a major life-threatening complication of thalassemia major and other iron-loading anemias treated by regular blood transfusions. Although the clinical manifestations of iron overload may be prevented by desferrioxamine, the only iron-chelating drug in routine clinical use, this treatment requires subcutaneous infusion of desferrioxamine for 12 hours each day. New orally effective iron chelators are urgently needed, and pyridoxal isonicotinoyl hydrazone (PIH), which was first recognized as an effective iron chelator in vitro and subsequently in vivo, shows promise for the treatment of iron overload. More recently, over 40 analogs of PIH were synthesized, and some of them proved to be very potent in mobilizing 59Fe in vitro from 59Fe-labeled cells. In this study, we show that PIH analogs such as pyridoxal benzoyl hydrazone, pyridoxal p-methoxybenzoyl hydrazone (PMBH), pyridoxal m-fluorobenzoyl hydrazone (PFBH), and pyridoxal-2-thiophenecarboxyl hydrazone, compounds previously shown to mobilize iron from cells in vitro, are also effective in vivo. All of these chelators significantly enhanced biliary excretion of iron (measured by atomic absorption spectrophotometry) following their intraperitoneal (IP) and/or oral administration to rats. The most effective was PFBH, which increased iron concentration in the bile about 150-fold, as compared with basal biliary iron concentration, within 1 hour following a single IP dose of 0.2 mmol/kg body weight. In contrast, desferrioxamine increased the biliary iron concentration only 20-fold to 30-fold under the same conditions. Moreover, while control rats excreted approximately 0.8 microg Fe in 2 hours, treatment with PFBH, PMBH, and desferrioxamine resulted in cumulative excretions of 87, 59, and 22 microg Fe, respectively, in the same period of time. Interestingly, PMBH was also quite effective following gastric administration, resulting in a 6-hour cumulative value of 34 microg Fe. These compounds are nontoxic and are inexpensive and easy to make. Their further evaluation as candidate drugs for the treatment of iron overload is warranted.

Animals↗

The occupational disease and injury compensatory system in the Czech Republic.

The article deals with methods of evaluation of occupational diseases and injuries in the Czech Republic (occupational injuries, occupational diseases and intoxications, other damage caused by work) and with the types of social and financial compensation of patients suffering from the above conditions.

Accidents, Occupational↗

Biological monitoring of child lead exposure in the Czech Republic.

The area around the Pribram lead smelter has been recognized to be heavily contaminated by lead (Pb). In the early 1970s, several episodes of livestock lead intoxication were reported in this area; thereafter, several epidemiological and ecological studies focused on exposure of children. In contrast to earlier studies, the recent investigation (1992-1994) revealed significantly lower exposure to lead. From 1986-1990, recorded average blood lead levels were about 37.2 micrograms lead (Pb)/100 ml in an elementary school population living in a neighborhood close to the smelter (within 3 km of the plant). The present study, however, has found mean blood lead levels of 11.35 micrograms/100 ml (95% CI = 9.32; 13.82) among a comparable group of children. In addition to blood lead, tooth lead was used to assess exposure among children. Statistically significant differences (p < 0.05) were observed between the geometric mean tooth lead level of 6.44 micrograms Pb/g (n = 13; 95% CI = 3.95; 10.50) in the most contaminated zone and 1.43 micrograms Pb/g (n = 35; 95% CI = 1.11; 1.84) in zones farther away from the point source. Both biomarkers, blood and tooth lead levels, reflect a similar pattern of lead exposure in children. This study has attempted a quantitative assessment of risk factors associated with elevated lead exposure in the Czech Republic. Content of lead in soil, residential distance from the smelter, consumption of locally grown vegetables or fruits, drinking water from local wells, the mother's educational level, cigarette consumption among family members, and the number of children in the family were factors positively related (p < 0.05) to blood lead levels. The resulting blood lead level was found to be inversely proportional to the child's age.

Adolescent↗

Screening of the gasoline lead load in school children in the Czech Republic.

The determination of erythrocyte zinc protoporphyrin (ZZP) was implemented as an indirect method for assessing lead levels in the blood in the follow-up of Czech children regarding the lead load due to automobile traffic. Simultaneously, basic indicators of the red blood picture were studied. A screening study was conducted with 2668 school-age children residing permanently in three different regions of our country. The differences in basic hematological indicators, i.e. number of erythrocytes, hemoglobin content, hematocrit and red blood cell volume, like the differences in zinc protoporphyrin in the peripheral blood, did not confirm the initial hypothesis on the relatively greater load of the Czech child population due to lead from exhaust fumes of combustion motors. Also, no regional differences were observed. The differences found in the abovementioned indicators reflect the influence of an overall environmental pollution rather than that of a toxic effect of lead.

Child↗

Hazardous wastes in Eastern and Central Europe [meeting report].

The countries of Eastern and Central Europe have emerged from a political system which for decades has ignored protection of human health from hazardous wastes. While the economies of the countries in this region are stretched, awareness and concern about hazardous waste issues are a part of the new realities. At a recent conference sponsored in part by the National Institute of Environmental Health Sciences, representatives of seven countries in the region described the status of hazardous waste programs, issues of major concern, and steps being taken to protect human health. This report summarizes the deliberations, outlines some of the problems remaining in dealing with the legacy of the past, addressing the problems of the present, and providing a framework for future research and collaborative efforts.

Environmental Pollutants↗

Exposure to lead and human health in the Czech Republic.

The aim of presented review is to address the most relevant issues related to the health effects caused by the human exposure to lead, as they have been recognized in Czech Republic in the period of 1992-1994 within the framework of the National Integrated Programme on Environment and Health (NIPEH) approved in 1992 and supported by WHO-European Centre for Environment and Health (WHO-ECEH), Bilthoven, The Netherlands and by the Government of the Netherlands. Basic sources of environment exposure to lead are identified and the fate of lead in the individual compartments of the environment is discussed. Relevant methods used for the exposure evaluation are summarized and the highest-risk group of population is defined. Attention is being paid to the effects of the long-term exposure to low lead levels, while other exposure settings are intentionally omitted. Interventional measures developed in the Czech Republic in attempt to reduce the environmental exposure are introduced. Instead of presenting specific data, current state-of-art and general trends are presented; list of references tries to combine the internationally recognized studies with those coming from national sources.

Aged↗

In vivo and in vitro efficacy of a new carbodithioate for the mobilization of cadmium.

Female Wistar rats with chronic cadmium intoxication (oral exposure to low dosages of CdCl2 in drinking water over a period of 90 d) were used to examine the in vivo ability of a newly developed chelator, sodium N-(4-methylbenzyl)-4-O-(beta-D-galactopyranosyl)-D-glucamine-N- carbodithioate (MeBLDTC), singly and in combination with sodium 4-carboxy-amidopiperidine-N-carbodithioate (INADTC) as agents to induce the biliary and urinary excretion of cadmium. The combined administration of the two dithiocarbamates, which differ greatly in molecular weight and structural features, led to a synergistic increase in the biliary excretion of cadmium and an enhanced reduction of renal cadmium levels. The use of such a coadministration produced an increase in the biliary excretion of cadmium that was more than double that expected if the compounds acted in an additive fashion. Such mixed-chelation therapy has potential utility in the treatment of human chronic cadmium intoxication. The hepatocytes isolated from chronically Cd-intoxicated rats were used as an in vitro screening model system for the new chelator. The plasma membrane integrity study with MeBLDTC at 0.48 mmol/20 ml of hepatocyte incubate using the trypan blue exclusion test and lactate dehydrogenase (LDH) leakage test revealed no differences in the cell viability with or without chelator. The cellular metabolic competence measured as the rate of urea synthesis also did not show any marked deviation from that of controls when incubated with MeBLDTC at three different concentrations. In the hepatocyte cultures, MeBLDTC induced a significant removal of cadmium from the hepatocytes at concentrations as low as 0.04 mmol/20 ml.

Animals↗

Chemical risk assessment and management in Czech and Slovak Republics.

For more than 40 years, former Czechoslovakia has made minimal efforts to protect the environment. As a result, newly formed republics suffer from some of the worst environmental pollution in Europe. In all stages of a complex process of improving chemical safety both countries are facing tremendous problems: lack of efficient and powerful legislative measures, inadequate and sometimes non-reliable data, shortage of sophisticated equipment, virtual absence of basic knowledge and, generally, persisting distrust between public and governmental institutions in health and environmental issues. These factors have made the beginning of new approaches extremely difficult. However, a great effort of many people in both republics together with a substantial assistance of both international organizations and national institutions from developed countries seem to be promising. It could help to move former position of largely ineffective measures and investments to one where limited funds are spent to achieve public benefits.

Czech Republic↗

Distribution and excretion of cadmium and nickel after simultaneous exposure and the effect of N-benzyl-D-glucamine dithiocarbamate on their biliary and urinary excretion.

A rat model for combined exposure to cadmium and nickel is presented that involves the administration of drinking water containing these elements over a period of 90 d. Coadministration of these two ions in drinking water leads to brain levels of both elements that are significantly higher than results from the administration of equal doses of the metals individually. The enhanced biliary excretion of cadmium in rats given sodium N-benzyl-D-glucamine dithiocarbamate (BGDTC) is almost twice as great in those animals given cadmium and nickel as in those animals given cadmium only. The excretion of nickel is reduced by the administration of this chelating agent. Although equal amounts of nickel and cadmium were administered to these animals, liver and kidney cadmium levels were approximately 100 times greater than the corresponding nickel levels. The results suggest that combined exposure to these elements may lead to enhanced levels of nickel and cadmium in the brain and a level of nervous system damage not predictable from information obtained under conditions of exposure to only one of these elements.

Administration, Oral↗

The study of exposure to cadmium in the general population. II. Morbidity studies.

An epidemiological study was performed to assess whether environmental pollution by cadmium as found in cadmium polluted areas of CSFR (Pribram and Frýdek-Mistek) is associated with changes in biological indicators of renal dysfunction in non-occupationally exposed population groups. Polluted areas were chosen on the basis of existing sources of Cd emission. The city of Prague was selected as a control area. Environmental monitoring (Cd in air, dust fall and soil) did not confirm significant contamination of selected areas. It was found that Cd levels in urine (Cd-U) of inhabitants living in areas chosen as Cd-contaminated were significantly higher than in the control area. Differences in concentrations of Cd in blood (Cd-B) levels between individual areas were not significant. No significant differences between the study populations were noted in the urinary excretion of low molecular weight proteins (beta 2-microglobulin, retinol binding protein) and albuminuria. However, total proteinuria and aminoaciduria in persons living in Pribram area was significantly higher. This area suffers from combined contamination by cadmium and lead. In smokers of both sexes the Cd-B levels were significantly higher in all areas, no significant differences were found in Cd-U levels. However, it was found that in smokers there is higher percentage of persons excreting more than 0.9 micrograms Cd.g-1 creatinine in urine. Consumption of home-grown vegetable and fruit in Cd-polluted areas led to significantly higher levels of Cd-B and Cd-U and total proteinuria. The results of the study show that smoking and food seem to be the most important sources of Cd intake in non-occupationally exposed populations. In spite of the fact that environmental monitoring does not reveal a significant contamination of selected areas by Cd, Cd-U levels confirmed that population living in these areas is really exposed to Cd.

Cadmium↗

Influence of age and time of administration of dithiocarbamate analogues on cadmium retention in rats.

In the present study the influence of age and time of chelation therapy on cadmium retention in 6-, 11-and 14-day-old rats and in 6-week-old rats has been investigated. Chelating agents N-benzyl-dithiocarboxy-D-glucamine (BDCG), sodium N-(metho-xybenzyl)-D-glucamine dithiocarbamate monohydrate (MeOBDCG) and N-methyl-N-dithiocarboxy-D-glucamine (MDCG) were administered intraperitoneally to three different groups at a dose of 1 mmol kg-1 body weight on two occasions following 115mCd intraperitoneal administration; immediately and after 24 h; after 24 h and 48 h; or after 48 h and 72 h. The 115mCd retention in the whole body and organs was determined 6 days after cadmium administration. Chelation therapy very effectively reduced cadmium retention in the whole body and organs, MeOBDCG being the most effective. The effects of chelating agents were significantly more pronounced in older than younger animals and in the case of early rather than late administration. The highest fraction of cadmium administered was retained in the liver, where also the strongest effect of chelation therapy was observed. Mobilized cadmium was excreted almost exclusively by the faecal route.

Aging↗