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Exposed Groups (exposed + groups)
Selected AbstractsMitochondrial control region variation in bank voles (Clethrionomys glareolus) is not related to Chernobyl radiation exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2007Heather N. Meeks Abstract ,Three previous studies at Chernobyl, Ukraine, documented elevated mitochondrial DNA diversity in bank voles (Clethrionomys glareolus) from radioactively contaminated sites. Little evidence was found to link patterns of diversity in contaminated areas to radiation exposure, but the experimental design precluded discriminating among alternative explanations for elevated diversity in exposed groups. Reference sites selected for the studies were relatively distant from contaminated sites and, additionally, were separated from contaminated sites by large river systems; thus, we hypothesized that differences among sites were correlated with geographic isolation rather than with radiation exposure. For the present study, we added three reference sites, which were selected based on minimal radioactive contamination, proximity to contaminated sites, and absence of obvious barriers to dispersal. We hypothesized that neighboring reference sites should exhibit levels and patterns of diversity similar to those of contaminated sites if the previously detected differences were, in fact, caused by geographic isolation. Indeed, levels of diversity in nearby reference sites are comparable to levels in contaminated sites. Additionally, nearby reference sites contain several haplotypes not observed at other study sites. Our results suggest that levels of diversity in contaminated regions are more plausibly explained by ecological and historical factors than by increased mutational pressure resulting from exposure to Chernobyl radiation. [source] Diflubenzuron inhibits reproduction of different strains of Drosophila melanogasterINSECT SCIENCE, Issue 4 2009Zbigniew Adamski Abstract, The effect of (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea) insecticide , diflubenzuron , on wild type and white type fruit flies Drosophila melanogaster (Meigen, 1830) was studied. Adult insects were placed in vials with different concentrations of the insecticide in the nutrient (from 0.048 to 48 mg of diflubenzuron per 1 cm3 of the nutrient). In each case, the insects showed some mortality, which was concentration-dependant. When comparing both strains, we could observe different acute toxicities, with wild type being more resistant to diflubenzuron. However, subacute toxicity was similar within both strains. In both strains the prolonged exposure led to the extinction of the majority of the populations (>70%). Although imagoes could freely copulate, we did not observe copulating fruit flies, and we did not find either eggs or larvae in any of the exposed groups. These results indicate that genetic mutation which leads to different eye colour can also affect resistance and survival of insects in pesticide-exposed areas. [source] Lack of teratogenicity of microcystin-LR in the mouse and toadJOURNAL OF APPLIED TOXICOLOGY, Issue 1 2002N. Chernoff Abstract Microcystin-LR (MC-LR) is a cyanobacterial toxin generated by the organism Microcystis aeruginosa. Although the hepatotoxicity of this chemical has been characterized, the potential developmental toxicity in vertebrates has not been well studied. The purpose of this study was to elucidate the effects of this toxin on the in vivo and in vitro development of mammals and the development of an Anuran (toad). Initial acute toxicity experiments with female CD-1 mice were accomplished with MC-LR administered i.p. in saline. Lethality occurred at 128 and 160 µg kg ,1 and histopathology revealed massive hepatic necrosis with diffuse hemorrhage. Developmental toxicity studies were done with MC-LR administered i.p. for 2-day periods: gestation days 7,8, 9,10 or 11,12. Doses used ranged from 2 to 128 µg kg,1. On gestation day 17, fetuses were weighed and analyzed for gross morphological and skeletal defects. No treatment-related differences were seen in litter size, viability, weight or the incidence of anomalies. Groups of dams dosed with 32,128 µg kg,1 on gestation days 7,8, 9,10 or 11,12 were allowed to give birth and the growth and development of their pups were followed postnatally. There were no significant effects noted in the offspring of the treated dams. Neurulation-staged CD-1 mouse conceptuses were exposed to 50,1000 nM MC-LR in whole embryo culture for 24 h. No significant increase in abnormalities or developmental delays was observed. Finally, exposure of the developing toad. Bufo arenarum was done from stage 17 (tail bud) for 10 days at concentrations of 1,20 mg l,1. No effect on morphological development or survival was noted in any exposed groups. These data indicate that microcystin does not appear to affect development adversely in the mouse (in vivo or in vitro) or the toad at the doses and exposure parameters used. Copyright © 2002 John Wiley & Sons, Ltd. [source] Renal, vascular and cardiac fibrosis in rats exposed to passive smoking and industrial dust fibre amositeJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 11-12 2009Peter Boor Abstract Passive smoking is an independent risk factor for cardiovascular diseases. Industrial fibrous dust, e.g. the asbestos group member, amosite, causes lung cancer and fibrosis. No data are available on renal involvement after inhalational exposure to these environmental pollutants or of their combination, or on cardiovascular and renal toxicity after exposure to amosite. Male Wistar rats were randomized into four groups (n= 6): control and amosite group received initially two intratracheal instillations of saline and amosite solution, respectively. Smoking group was subjected to standardized daily exposure to tobacco smoke for 2 hrs in a concentration resembling human passive smoking. Combined group was exposed to both amosite and cigarette smoke. All rats were killed after 6 months. Rats exposed to either amosite or passive smoking developed significant glomerulosclerosis and tubulointerstitial fibrosis. Combination of both exposures had additive effects. Histomorphological changes preceded the clinical manifestation of kidney damage. In both groups with single exposures, marked perivascular and interstitial cardiac fibrosis was detected. The additive effect in the heart was less pronounced than in the kidney, apparent particularly in changes of vascular structure. Advanced oxidation protein products, the plasma marker of the myeloperoxidase reaction in activated monocytes/macrophages, were increased in all exposed groups, whereas the inflammatory cytokines did not differ between the groups. In rats, passive smoking or amosite instillation leads to renal, vascular and cardiac fibrosis potentially mediated via increased myeloperoxidase reaction. Combination of both pollutants shows additive effects. Our data should be confirmed in subjects exposed to these environmental pollutants, in particular if combined. [source] Population-based study of non-infectious rhinitis in relation to occupational exposure, age, sex, and smokingAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2002Johan Hellgren MD Abstract Background Many types of occupational exposure are associated with the risk of non-infectious rhinitis. We investigate the risk factors for this association. Methods A random population of 2,044 subjects (aged 21,51) answered a questionnaire that was comprised of detailed questions on occupational exposure, nasal complaints, and smoking. NIR was defined as the sensation of nasal blockage and/or attacks of sneezing without having a cold. The incidence rates for NIR among exposed and unexposed were calculated. In the different exposed groups, only NIR with onset after the start of exposure was regarded as exposed. If a subject reported NIR before the relevant exposure started, he/she was excluded from that analysis. Relative risks (RR) were calculated as incidence rate ratios. Odds ratios controlling for smoking, age, and atopy were also calculated. Results The incidence rate for NIR was 13.5/1,000 person-years. Males exposed to fire fumes (RR 2.5, 95% confidence interval (CI) 1.5,4.1), women exposed to paper dust (RR 2.0, 95% CI 1.5,2.9), and male cleaners (RR 3.1, 95% CI 1.9,5.1) displayed an increased risk of developing NIR. Smoking was associated with an increased risk of NIR for both sexes. Conclusion Exposure to several occupational irritants is associated with a higher risk of developing NIR. Am. J. Ind. Med. 42:23,28, 2002. © 2002 Wiley-Liss, Inc. [source] Four Weeks' Inhalation Exposure of Long Evans Rats to 4- tert -Butyltoluene: Effect on Evoked Potentials, Behaviour, and Brain NeurochemistryBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2000Henrik Rye Lam Long-lasting central nervous system (CNS) neurotoxicity of 4- tert -butyltoluene (TBT) has been investigated using electrophysiology, behaviour, and neurochemistry in Long Evans rats exposed by inhalation to 0, 20, or 40 p.p.m. TBT 6 hr/day, 7 days/week for 4 weeks. Flash evoked potentials and somatosensory evoked potentials were not affected by TBT. In Auditory Brain Stem Response there was no shift in hearing threshold, but the amplitude of the first wave was increased in both exposed groups at high stimulus levels. Three to four months after the end of exposure, behavioural studies in Morris water maze and eight-arm maze failed to demonstrate any TBT induced effects. Exposure was followed by a 5 months exposure-free period prior to gross regional and subcellular (synaptosomal) neurochemical investigations of the brain. TBT reduced the NA concentration in whole brain minus cerebellum. Synaptosomal choline acetyltransferase activity increased and acetylcholinesterase activity was unchanged suggesting increased synaptosomal ability for acetylcholine synthesis. The relative and total yield of synaptosomal protein was reduced suggesting reduced density and total number of synapses in situ, respectively. We hypothesise that a reduced yield of synaptosomal protein reflects a more general effect of organic solvent exposure on the software of the brain. The synaptosomal concentration per mg synaptosomal protein and the total amount of 5-hydroxytryptamine were not affected whereas the total amount of synaptosomal noradrenaline decreased. The concentration and the total amount of synaptosomal dopamine decreased. The noradrenergic and dopaminergic parts of CNS may be more vulnerable to TBT than the serotonergic, and these long-lasting effects may cause or reflect TBT-compromised CNS function. [source] Carcinogenicity test in B6C3F1 mice after parental and prenatal exposure to 50 Hz magnetic fieldsBIOELECTROMAGNETICS, Issue 3 2002Yoshihisa Otaka Abstract Some epidemiological studies suggest association of childhood cancer with occupational exposure of the parents to magnetic fields. To test this relationship, 50 each of C57BL/6J female and C3H/HeJ male mice were exposed for 2 and 9 weeks, respectively, to 50 Hz sham (group A), 0.5 (group B), and 5 mT (group C) sinusoidal alternating magnetic fields. They were mated under the exposure for up to 2 weeks, and the exposure was continued until parturition. All the B6C3F1 offspring, without adjusting numbers of animals, were clinically observed without exposure to magnetic field for a nominal 78 weeks from 6,8 weeks of age after weaning and then euthanized for pathological examination according to a routine carcinogenicity test. 540 pups entered the test, and the survival rate was 96.7%. No F1 mouse died of tumoral diseases before a male in A group died of stomach cancer at 43 weeks of age. The first animal death in the exposed groups due to tumor occurred at 71 weeks of age. Eighteen animals died before necropsy at 84,86 weeks of age. No significant difference was detected in the final number of survivors and incidence of tumors between groups A and B, or A and C. Concerning reproduction total implants in group B were less than in group A and the difference was on the borderline of significance (P,=,.05). This difference was not reproduced in a later duplicate experiment. Bioelectromagnetics 23:206,213, 2002. © 2002 Wiley-Liss, Inc. [source] Hypothyroidism in neonates post-iodinated contrast media: a systematic reviewACTA PAEDIATRICA, Issue 10 2009Alexandra Ahmet Abstract Aim:, To determine if neonates exposed to iodinated contrast media are at risk of hypothyroidism. Methods:, A systematic review was conducted by searching electronic databases (e.g. MEDLINE), contacting experts and scanning reference lists. Studies examining the effects of contrast media on neonatal thyroid function were included. Two reviewers independently screened the literature and assessed the risk of bias, while one reviewer abstracted data. Results:, Eleven studies were included; nine studies directly examined the risk of hypothyroidism (n = 182 neonates exposed to contrast media). All were highly affected by bias. In the three studies including term infants, one showed a trend towards increased thyroid-stimulating hormone (TSH) and decreased free thyroxine (FT4) among exposed groups. Six of 72 (8.3%) term infants exposed were treated for hypothyroidism. In studies of premature infants, there was a trend towards increased TSH (n = 3/7 studies), lower total thyroxine (n = 1), decreased triidothyronine and FT4 (n = 3) and hypothyroidism (n = 5). Twenty of 110 (18.2%) premature infants exposed were treated for hypothyroidism. Conclusion:, Hospitalized neonates exposed to iodinated contrast media are at risk for abnormal thyroid function and development of hypothyroidism. Premature infants might be at increased risk. Well-controlled studies are required to replicate our findings because the included studies were highly affected by bias. [source] | |||||||||||||