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Biomedical subjects

U Ewers

Publications and source records attributed to U Ewers.

At least 55 records · Page 3Linked to original sources
PubMed1985

Environmental exposure to cadmium and renal function of elderly women living in cadmium-polluted areas of the Federal Republic of Germany.

An epidemiological study was performed to assess whether environmental pollution by cadmium as found in cadmium-polluted areas of the Federal Republic of Germany is associated with an increased prevalence of biological signs of kidney dysfunction in population groups non-occupationally exposed to heavy metals. The study was run in two industrial areas known to be highly contaminated by cadmium, lead and other heavy metals, viz. Stolberg and Duisburg. Düsseldorf was selected as a reference area. As a study population we selected 65- and 66-year-old women (n = 286) who had spent the major part of their lives in one of these areas. The average cadmium levels in blood (CdB) and urine (CdU) revealed significant differences in exposure to cadmium in the order Stolberg greater than Duisburg greater than Düsseldorf. Serum creatinine levels were, on average, significantly higher in the Stolberg group than in the Duisburg and Düsseldorf groups. However, with respect to the urinary excretion of low molecular weight proteins (beta 2-microglobulin, retinol-binding protein), albuminuria, total proteinuria, aminoaciduria, phosphaturia and some other biological findings, no significant differences between the study populations were noted. Similarly, the prevalence of clinically-confirmed hypertension as well as the relative frequency of hypertensive subjects (systolic greater than or equal to 160 and/or diastolic greater than or equal to 95 mm Hg) did not differ significantly among the three study groups. There was no exposure-response relationship between CdU and tubular proteinuria in the range of the CdU-levels found (0.1 to 5.2 micrograms/g creatinine). However, albuminuria tended to be increased at CdU levels greater than 2 micrograms/g creatinine.

Aged↗
PubMed1983

Neuropsychological studies in children with elevated tooth-lead concentrations. II. Extended study.

Results from neuropsychological tests, collected under double-blind-precautions, were evaluated for 115 schoolage children (mean age: 9.4 years) living in a lead smelter area (Stolberg, FRG). Tooth-lead concentrations (PbT) from shed incisor teeth as measures of longtime lead-exposure were available for these children (mean = 6.16 ppm; range: 1.9-38.5 ppm), and for 83 of them blood-lead concentrations (PbB) were available as well (mean = 14.3 micrograms/dl; range: 6.8-33.8 micrograms/dl). The following functional capacities were tested: intelligence (German WISC), perceptual-motor integration (Göttinger Formreproduktionstest = GFT, Diagnosticum for Cerebralschädigung = DCS), reaction performance (Wiener Determinationsgerät), finger-wrist tapping-speed, and repetitive cancellation-performance (Differentieller Leistungstest). In addition standardized behavior ratings were obtained by the examiners, the mothers, and the teachers. Multiple stepwise regression-analysis (forced solution) was calculated for outcome-variables and Pb-tooth, including age, sex, duration of labor, and socio-hereditary background as covariates. Significant (P less than 0.05) or near-significant (P less than 0.1) association was established between Pb-tooth and GFT-performance (errors), reaction-performance (false reactions), and four behavioral dimensions as rated by the mothers, namely distractability, restlessness, lack of information, and wasting of time; the proportion of explained variance never exceeded 6%, however. No significant association was found between PbT and WISC verbal-IQ after the effects of "socio-hereditary background" had been eliminated, although there was still a tendency for high level-children (PbT greater than 10 ppm) to be inferior to low level-children (PbT less than or equal to 4 ppm) by 4.6 IQ-points after correction for confounding. There was a near-significant, inverse relationship between finger-wrist tapping-speed and Pb-blood. The results are discussed within the framework of attention-deficit disorder, and compared to neurobehavioral Pb-effects from animal-experiments, which provide suggestive evidence for a causal relationship between developmental lead-exposure and certain neurobehavioral deficits.

Child↗
PubMed1983

Repeated surveillance of exposure to thallium in a population living in the vicinity of a cement plant emitting dust containing thallium.

From 1979 to 1981, several medical surveys were carried out among a population living in the vicinity of a cement plant that emitted dust containing thallium until August, 1979. Air, soil, plants, and domestic animals in the area were contaminated by thallium and this led to an increased intake of thallium in the population, mainly due to the consumption of home-grown vegetables and fruit. In order to assess the degree of the individuals' exposure to thallium, thallium levels in 24-h urine samples (TlU) were determined. Three surveys were carried out from September to December, 1979 to assess the degree of thallium exposure of different parts of the general population. Subjects with relatively high exposure, as indicated by the results of the above mentioned population surveys, or those suffering from health disorders that might be related to an increased intake of thallium, were reexamined several times from 1979-1981. Special attention was also given to children attending a kindergarten situated about 0.5 km from the cement plant. As compared to an "unexposed" reference population (mean TlU: 0.3 microgram/l), the majority of the population living in the cement plant area had significantly elevated urinary thallium levels (range: less than 0.1-76.5 micrograms/l) indicating a substantially increased environmental exposure. A reduction of the intake of thallium was mainly achieved by the fact that the population, as advised by the authorities, largely avoided the consumption of home-grown, potentially contaminated foodstuffs. Reports on the teratogenicity of thallium in certain animal species caused great concern that thallium might have exerted teratogenic effects on the newborn of women exposed to thallium during pregnancy. Therefore, an investigation of children born between January, 1978 and August, 1979 (n = 297) was carried out. Although the number of congenital malformations was greater than expected, we conclude, considering carefully all data available, that there is likely no causal relationship between thallium and the occurrence of congenital malformations in the children investigated.

Abnormalities, Drug-Induced↗
PubMed1983

Levels of cadmium and lead in blood in relation to smoking, sex, occupation, and other factors in an adult population of the FRG.

Levels of cadmium (CdB) and lead (PbB) were determined in the blood of 579 60-65 year-old residents of Cologne and two small cities near Cologne. CdB-levels in cigarette smokers are on the average 3-4 times higher than in non-smokers (geometric means: non-smokers, 0.44 micrograms/l; less than or equal to 10 cigarettes/d, 1.16 micrograms/l; greater than 10 cigarettes/d, 1.85 micrograms/l). The results indicate that, with regard to the internal dose, cadmium exposure via smoking may contribute even more than does exposure via food. PbB-levels (geometric mean: 8.49 micrograms/100 ml; range: 2.9-30.3 micrograms/100 ml) are in the acceptable range as defined by the CEC reference values. Male smokers have on the average slightly higher PbB-levels than male non-smokers. In women PbB-levels are on the average lower than in men.

Aged↗
PubMed1983

[Are suppressor T-cells the primary target cells of lead immunotoxicity?].

Studies were performed to investigate the effect of chronic low level lead exposure on the regulatory functions of T cells in the humoral immune response to sheep red blood cells (SRBC) in mice. Female mice were exposed to lead (as lead acetate) in the diet at 545 (group 1) and 2180 ppm (group 2) for 10 weeks. Lead exposure resulting in blood lead levels (PbB) of about 50 micrograms/100 g (group 1) produced a substantial increase of the number of IgG antibodies secreting spleen cells on days 3 and 4 after challenge. At the higher exposure level (group 2; PbB 60-80 micrograms/100 g) a suppression of the number of IgG plaque forming cells was observed. The IgM response was much smaller than the IgG response. Although differences between the group means were small, the results indicate that there also is an enhancement of the IgM response in the lower dosage group on days 3 and 4. In a second experiment the effect of in vivo lead exposure on antigenic competition was examined. Lead substantially reduced the effect of antigenic competition. Results of both experiments suggest that suppressor T cells rather than helper T cells may represent the primary target for lead. Throughout this study serum complement C3 levels were determined. Complement C3 levels tended to be reduced in the lead exposed groups before as well as after inocculation with SRBC.

Animals↗
PubMed1982

Lead in deciduous teeth of children living in a non-ferrous smelter area and a rural area of the FRG.

Lead concentrations were measured in the deciduous teeth (incisors) of 302 children living in a lead-smelter area in the FRG (Stolberg, Rheinland) and of 86 children living in a nonpolluted rural area (Gummersbach, Bergisches Land). Blood lead levels were determined in 83 of the children living in the lead-smelter area. On average, tooth lead levels of children living in the smelter area (mean: 6.0 microgram/g; range: 1.49-38.5 microgram/g) were significantly higher than those of children living in the rural area (mean: 3.9 microgram/g; range: 1.6-9.4 microgram/g). Blood lead levels were 6.8-33.8 microgram/100 ml (mean: 14.3 microgram/100 ml). Children of lead-workers had on average higher tooth lead and blood lead levels than children of people who were not lead-workers. Tooth lead levels increased with increasing duration of residence in the lead-smelter area and with the degree of local environmental pollution by lead, as indicated by the lead content of the atmospheric dust fall-out around the children's homes. The correlation coefficient of tooth lead vs blood lead was 0.47. The intra-individual variability of tooth lead levels was low (r = 0.86), and tooth lead levels of brothers and sisters were similar (r = 0.75), suggesting that tooth lead may be used as a representative and reliable indicator of long-term lead exposure.

Child↗
PubMed1981

Intake and health effects of thallium among a population living in the vicinity of a cement plant emitting thallium containing dust.

In order to assess the degree of thallium exposure in a population living around a thallium emitting cement plant in a small city in North-West Germany thallium levels in 24 h urine samples of 1,265 subjects and in hair samples of 1,163 subjects were determined. Urinary thallium levels in two groups of subjects living in an urban and a rural area of West Germany were determined for reference. As compared to these subjects the population living around the cement plant exhibited obvious signs of increased thallium intake. The mean urinary thallium concentration was 2.6 micrograms/l and ranged up to 76.5 micrograms/l. In contrast, the mean urinary thallium levels of the two reference groups were 0.2 and 0.4 micrograms/l, respectively. Hair thallium levels of the population living around the cement plant were also markedly increased (mean: 9.5 ng/g). The major route of the population's increased intake of thallium was found to be the consumption of vegetables and fruit grown in private gardens in the vicinity of the cement plant. As was shown by chemical analyses vegetables and fruit grown in these gardens were contaminated by thallium-containing atmospheric dust fall-out caused by emissions of the cement plant. The pulmonary route of uptake as well as other sources did not seem to play a significant role in the population's exposure to thallium. Polyneuritic symptoms, sleep disorders, headache, fatigue and other signs of psychasthenia were found to be the major health effects associated with increased thallium levels in urine and hair. No positive correlation was found between the thallium levels in hair and urine and the prevalence of skin alterations, hair-loss and gastro-intestinal dysfunctions.

Adolescent↗
PubMed1980

Effects of lead, cadmium and mercury on brain adenylate cyclase.

The effects of lead, cadmium and mercury ions on adenylate cyclase activity of rat cerebrum, cerebellum and brain stem were studied in vitro and in vivo. Adenylate cyclase activity in homogenates of cerebellum as well as cerebrum and brain stem was found to be inhibited by micromolar concentrations of these heavy metal ions in vitro. Administration of lead acetate trihydrate (25 mg/kg body wt i.v.) produced an initial increase of adenylate cyclase activity in the cerebellum and brain stem 1 h after injection, followed by a significant decrease of enzyme activity in cerebrum and cerebellum 4 h after the injection. Chronic lead treatment achieved by feeding lead containing diets, which generated blood lead levels of 31.3 +/- 3.8, 68.8 +/- 1.5 and 121.5 +/- 8.6 microgram Pb/100 g blood resp., produced a significant increase of brain lead levels and a 10-30% reduction of adenylate cyclase activity in cerebrum, cerebellum and brain stem. Phosphodiesterase activity was reduced under these conditions in the range of 10-20% in cerebellum and brain stem, but not in cerebrum.

Adenylyl Cyclase Inhibitors↗
PubMed1980

[Influence of chronic lead exposure on resistence to bacterial infection (author's transl)].

Suppression by lead of resistance to bacterial or viral infections has been reported by several authors. We have studied, if a decrease of resistance to bacterial infection could be evaluated at blood lead concentrations (PbB), which correspond to the upper levels of environmental or occupational lead exposure regarded as tolerable (PbB = 35 resp. 60 microgram/100 ml). NMRI mice were chronically exposed to lead by feeding with lead acetate containing diets and given a challenge with Salmonella typhimurium. No increase of susceptibility to bacterial infection could be demonstrated at PbB < 90 microgram/100 g. At PbB > 100 microgram/100 g, however, an increase of lethality and a decrease of 50% survival times could be observed after bacterial infection.

Animals↗
PubMedDate not supplied

Results from the European multicenter study on lead neurotoxicity in children: implications for risk assessment.

In order to improve dose-response information on neurobehavioral effects of environmental lead exposure in children, the World Health Organization, Regional Office for Europe (WHO/EURO), in collaboration with the Commission of the European Communities, initiated this international study which was planned, executed and evaluated between 1984 and 1989. Eight groups from eight European countries (Bulgaria, Denmark, Greece, Hungary, Italy, Roumania, W. Germany and Yugoslavia) took part. A common study protocol with inherent quality assurance elements was developed to achieve comparability. Blood-lead concentrations (PbB) were the main markers of exposure. The WISC (4 subtests) for psychometric intelligence, the Bender Gestalt test (GFT version) and the Trail-Making test for visual-motor integration, the Vienna Reaction Device and a delayed RT task for reaction performance, and the Needleman scales for behavior ratings served as behavioral endpoints. All individual studies taken together represent a sample size of 1879 school-age children and cover a PbB range from below 5 to about 60 micrograms/100 ml. Overall statistical evaluation of outcome was done by multiple regression analysis using a uniform confounder model. The strongest and most consistent effects occurred for the Bender Gestalt test (GFT version) and for serial choice reaction performance (Vienna Device). The degree of association with PbB was significant for these variables, although the contribution of PbB to the observed variance never exceeded 0.8%. Psychometric intelligence was also negatively affected, although the consistency of outcome between studies was poor, and the association with PbB only borderline. An effort towards risk assessment was made by calculating the proportion of children at risk, using the observed regression coefficients as well as means and standard deviations.

Child↗