RESUMO
The mechanism of interaction between chlorpyrifos, an organophosphate insecticide, and methyl mercury, an organometal, was assessed utilizing the amphipod, Hyalella azteca. Previous studies have demonstrated that chlorpyrifos and methyl mercury interact additively, with survival as the endpoint. In addition, exposure to chlorpyrifos and methyl mercury increased the accumulation and decreased the elimination of methyl mercury. To elucidate the mechanism responsible for these interactions, biochemical mechanisms indicative of chlorpyrifos and methyl mercury toxicity were assessed in H. azteca. Biochemical endpoints that were evaluated include the inhibition of acetylcholinesterase enzyme and indicators of oxidative stress such as glutathione-S-transferase activity, lipid peroxidation, protein oxidation, and glutathione content. Methyl mercury antagonized the effects of chlorpyrifos in vivo on acetylcholinesterase inhibition. Methyl mercury did not induce oxidative damage; however, chlorpyrifos decreased glutathione-S-transferase activity. Additional studies demonstrated that methyl mercury did not affect the in vitro bioactivation of chlorpyrifos or the subsequent inhibition of acetylcholinesterase enzyme activity. Chemical-chemical interactions were examined utilizing chromatographic techniques. Results of thin layer chromatography suggested the formation of a chlorpyrifos-methyl mercury complex. The formation of this complex may result in increased accumulation of methyl mercury, apparent additive toxicity, and protection against chlorpyrifos mediated acetylcholinesterase inhibition.
Assuntos
Clorpirifos/toxicidade , Crustáceos/fisiologia , Inseticidas/toxicidade , Compostos de Metilmercúrio/toxicidade , Acetilcolinesterase/metabolismo , Animais , Clorpirifos/química , Inibidores da Colinesterase/toxicidade , Cromatografia em Camada Fina , Interações Medicamentosas , Cromatografia Gasosa-Espectrometria de Massas , Glutationa/metabolismo , Glutationa Transferase/metabolismo , Inseticidas/química , Peroxidação de Lipídeos/efeitos dos fármacos , Compostos de Metilmercúrio/análise , Oxirredução , Proteínas/metabolismoRESUMO
Twenty-eight keratoconic patients with either contact-lens intolerance or marked corneal scarring over the visual axis underwent lamellar keratoplasty for visual rehabilitation. All 28 patients returned for follow-up at six months, 27 (98%) had follow-up at one year, and 23 (82%) at two years. The 23 patients with two-year follow-up showed progressive improvement of visual acuity over time. At six months, 11 of 23 patients (48%) had visual acuity of 20/30 or better. At one year, 17 of 23 (74%) had 20/30 or better, and at two years, 21 of 23 (91%) had 20/30 or better. The average postoperative keratometry measurement at two years was 43.5 diopters (S.D. = 2.5 diopters), which represented an average reduction of 13 diopters from preoperative keratometry. All patients who were less than 32 years old obtained visual acuity of 20/30 or better after two years and reached this level significantly (F = 6.75, P = .02) sooner than those more than 32 years old. These results compare favorably with previously reported visual results after penetrating keratoplasty.
Assuntos
Transplante de Córnea/métodos , Ceratocone/fisiopatologia , Ceratocone/cirurgia , Acuidade Visual/fisiologia , Adolescente , Adulto , Criança , Seguimentos , Humanos , Pessoa de Meia-Idade , Fatores de Tempo , Testes VisuaisRESUMO
Chemical mixture interactions of chlorpyrifos, dieldrin, and methyl mercury were evaluated in Hyalella azteca. Survival of adult and juvenile organisms was evaluated following exposure to individual chemicals and in binary combinations. Binary interactions of the model chemicals on survival of adult and juvenile H. azteca were evaluated by concentration-response curve analysis as additive, synergistic, antagonistic, or independent. Chlorpyrifos and methyl mercury interacted additively, while dieldrin interacted independently with both chlorpyrifos and methyl mercury. Toxicodynamic interactions were evaluated by measuring accumulation and elimination of each model toxicant in the presence of a second toxicant. Chlorpyrifos significantly increased the amount of methyl mercury accumulated in the first 12 h of exposure. Dieldrin did not interact with chlorpyrifos or methyl mercury in the accumulation or elimination experiments. Accumulation of chlorpyrifos was not observed. Results of the current investigation demonstrate that chlorpyrifos and methyl mercury interact additively, which would otherwise be predicted to act independently.
Assuntos
Clorpirifos/toxicidade , Crustáceos/fisiologia , Dieldrin/toxicidade , Inseticidas/toxicidade , Compostos de Metilmercúrio/toxicidade , Animais , Clorpirifos/farmacocinética , Dieldrin/farmacocinética , Interações Medicamentosas , Inseticidas/farmacocinética , Compostos de Metilmercúrio/farmacocinética , Análise de SobrevidaRESUMO
Sediments and/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg/kg, while 1998 sediment concentrations in Sardis, Enid and Grenada Lakes were 0.112, 0.088 and 0.133 mg Hg/kg, respectively. Sediment mercury concentrations in 1999 were similar in all three lakes but, generally lower than 1998. Mean total mercury concentrations in edible fillets of fish collected from Enid Lake in 1998 were above the human health FDA action level (> 1.0 mg Hg/kg) for bass (1.40), crappie (1.69) and gar (1.89); however, tissue concentrations were less than 1.0 mg Hg/kg in carp (0.63) and catfish (0.82). Human hazard indexes for each species was > or = 1 for both adults and children, indicating that there is a potential for toxic effects to occur. In addition, calculated consumption limits indicate that adults may consume 4-12 oz. of fish per month, depending on the species consumed. For children, 2 oz. per month may be consumed. Further studies are needed to determine the exact environmental consequences and human health impacts associated with mercury contamination in North Mississippi and the Southeastern United States.
Assuntos
Monitoramento Ambiental , Peixes , Contaminação de Alimentos , Mercúrio/análise , Saúde Pública , Poluentes Químicos da Água/análise , Adulto , Animais , Criança , Dieta , Sedimentos Geológicos/química , Política de Saúde , Humanos , Mississippi , Medição de Risco , Distribuição TecidualRESUMO
A toxicological evaluation was conducted on wetland habitats created as a result of run-off from agricultural areas. These temporary wetlands were created by using drop pipes as a means of reducing erosional cutting in agricultural fields. Toxicity bioassays utilizing bacterial bioluminescence and Hyalella azteca were used to assess sediment pore water and whole sediment, respectively. Inhibition of bacterial bioluminescence was initially used to determine relative toxicities of pore water from ten wetland sites. Constructed wetland sites were compared to the University of Mississippi Biological Field Station, a relatively pristine reference site. The H. azteca ten day sediment toxicity test was utilized to assess sediment from four selected sites using survival and growth as toxicological endpoints. Results from the toxicological evaluation, along with extensive ecological evaluations, were used to assess the best approach for implementation of temporary wetland habitats with existing agricultural practices.
Assuntos
Monitoramento Ambiental/métodos , Água Doce/análise , Sedimentos Geológicos , Testes de Toxicidade , Agricultura/métodos , Animais , Bactérias , Crustáceos , ChuvaRESUMO
In recent years, there has been an increased use of the measurement of sex steroid hormone levels in the blood of animals exposed to chemicals as an indicator of reproductive impairment or an alteration in endocrine function. Although levels of hormones are often compared among animals and laboratories, there has been no study to examine the between-laboratory variability in actual steroid measurements. Therefore, we initiated a study with white sucker collected from a site receiving pulp mill effluent, previously documented as having reduced steroid levels, to address this issue. Samples of plasma and media from in vitro gonadal incubations were delivered to eight outside laboratories with the ability to measure steroid hormones. These laboratories ranged from well-established fish endocrine laboratories to wildlife toxicology laboratories, which have recently implemented the methods to measure steroid hormones. In this study, we have considered both the absolute measure of steroid content between laboratories as well as the ability to discriminate between reference and exposed populations as important criteria when evaluating the utility of these measures. Of the eight outside laboratories conducting the analyses, six detected identical site differences in circulating levels of testosterone and 17beta-estradiol to those documented by our Burlington laboratory (ON, Canada). However, the absolute value of the steroid hormones measured in the plasma varied significantly (plasma testosterone 0.6-23.1 ng/ml, 17beta-estradiol 77.6-1782.7 pg/ml) with coefficients of variation of 70.4% and 60.3% respectively. Similar results were demonstrated for the measurement of steroid hormones in media following in vitro gonadal incubation. Although there was a fair amount of variability in the absolute measure of steroid hormone levels, we would predict a far greater coherence of interlaboratory results through the sharing of reagents and the use of a common methodology between laboratories. These results are very promising, providing evidence for the inclusion of steroid hormones in monitoring endocrine disruption in wildlife species.
Assuntos
Sistema Endócrino/efeitos dos fármacos , Estradiol/sangue , Testosterona/sangue , Poluentes da Água/efeitos adversos , Animais , Monitoramento Ambiental/métodos , Feminino , Indústrias , Papel , Reprodutibilidade dos TestesRESUMO
An immunohistochemical assay for proliferating cell nuclear antigen (PCNA) identifies cells in all active phases of the cell cycle. In this study, PCNA methodology, which was developed primarily for mammalian tissues, was adapted to three small fish species, medaka (Oryzias latipes), guppy (Poecilia reticulata), and western mosquitofish (Gambusia affinis) that are used in carcinogenesis bioassays and environmental sentinel studies. Our study showed that PCNA can be identified in routinely processed, paraffin embedded specimens of these fishes. Optimum staining conditions were dependent on fixative, primary antibody, antigen retrieval processing, and protein blocking reagent. Best results were achieved using 10% neutral buffered formalin as the fixative, clone PC10 as the primary antibody, and a combination of powdered milk and bovine serum albumin as a protein block. Except for medaka specimens, antigen retrieval was not required for specimens preserved in 10% neutral buffered formalin, but was required for the other fixatives tested. In whole fish specimens, PCNA marked cells in normally proliferating tissues such as testis, ovary, primary filament epithelium of the gill, hematopoietic tissues, thymus, retina and alimentary tract. The study demonstrated the successful application of mammalian-based PCNA technology to these aquatic species. Further applications of the assay will aid in understanding the role of cell proliferation in normal, diseased, and toxicant-affected tissues of aquatic animals.
Assuntos
Ciprinodontiformes/metabolismo , Oryzias/metabolismo , Poecilia/metabolismo , Antígeno Nuclear de Célula em Proliferação/análise , 3,3'-Diaminobenzidina , Animais , Testes de Carcinogenicidade , Ciprinodontiformes/imunologia , Imuno-Histoquímica , Indicadores e Reagentes , Oryzias/imunologia , Inclusão em Parafina , Poecilia/imunologia , Fixação de TecidosRESUMO
The mechanism of interaction between chlorpyrifos, an organophosphate insecticide, and methyl mercury was assessed utilizing the amphipod, Hyalella azteca. Previous studies have demonstrated that chlorpyrifos and methyl mercury interact additively with survival as the endpoint. In addition, exposure to chlorpyrifos and methyl mercury increased the accumulation and decreased the elimination of methyl mercury. To further examine the mechanism responsible for these interactions, the in vivo and in vitro inhibition of acetylcholinesterase enzyme activity was assessed following exposure to methyl mercury and chlorpyrifos. In vivo, methyl mercury antagonized the effects of chlorpyrifos on acetylcholinesterase inhibition. Additional studies demonstrated that methyl mercury did not affect the in vitro bioactivation of chlorpyrifos or the subsequent inhibition of acetylcholinesterase enzyme activity. Chemical-chemical interactions were examined utilizing chromatographic techniques and suggested the formation of a chlorpyrifos-methyl mercury complex. The formation of this complex may result in increased accumulation of methyl mercury, apparent additive toxicity, and protection against chlorpyrifos-mediated acetylcholinesterase inhibition.
Assuntos
Clorpirifos/toxicidade , Crustáceos/efeitos dos fármacos , Inseticidas/toxicidade , Compostos de Metilmercúrio/toxicidade , Acetilcolinesterase/metabolismo , Animais , Clorpirifos/administração & dosagem , Inibidores da Colinesterase/toxicidade , Cromatografia em Camada Fina/veterinária , Interações Medicamentosas , Compostos de Metilmercúrio/administração & dosagemRESUMO
The time course of exposure to p-nonylphenol (NP) from two different sources was compared to equivalent exposures of 17-beta-estradiol (E2) and a solvent control (ethanol; EtOH). Japanese medaka were exposed for 4 days to a nominal concentration of 20 micrograms/l of either NP-I (Schenectady International, Inc.), NP-II (Aldrich), or E2, and were then placed in untreated water for 5 days. Tissue samples were taken at two time points during the 4-day exposure and two time points during the 5 days following exposure. Liver homogenates were analyzed using a western blot to detect vitellogenin (VTG) and quantified by measuring the optical density for each lane. Preliminary results indicate that E2 significantly increased VTG staining above the level observed in EtOH-treated controls for both males and females. A two-way analysis of variance (ANOVA) indicates that NP from both sources, as well as E2, significantly increased VTG staining in males (ANOVA, n = 48, P < 0.001; Tukey pairwise tests, all P < 0.008). A significant increase in VTG was observed in E2-treated males and females the first day following transfer into toxicant-free water (two-way ANOVAs, both n = 48, P < 0.003; Tukey pairwise tests, all P < 0.019). If confirmed, this extended response observed for low-level exposures may represent a significant factor for sampling scenarios following pulsitile exposure.
Assuntos
Oryzias/metabolismo , Fenóis/farmacologia , Poluentes Químicos da Água/farmacologia , Animais , Cromatografia Gasosa/veterinária , Relação Dose-Resposta a Droga , Estradiol/administração & dosagem , Estradiol/farmacologia , Feminino , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Fenóis/administração & dosagem , Vitelogeninas/análise , Poluentes Químicos da Água/administração & dosagemRESUMO
Triclosan is an antibacterial agent commonly used in industry and often detected in waste-water effluent. The potential of triclosan to act as an endocrine disruptor was examined because its chemical structure closely resembles known non-steroidal estrogens (e.g. DES, bisphenol A). Japanese medaka fry (Oryzias latipes) were exposed for 14 days beginning 2 days post-hatch to triclosan (100, 10, 1 micrograms/l), 17-beta estradiol (E2; 1 microgram/l), or a solvent control (ethanol). Two months post-exposure, the phenotypic sex of each adult was assessed visually using sexually dimorphic fin shape and size. The proportion of females in each group was similar for triclosan-exposed animals and solvent-treated controls (ethanol 53%, 1 ppb 58%, 10 ppb 45%, 100 ppb 36%) although E2 treatment did produce 92% female adults. Sexually dimorphic fin traits were quantified to look for potential effects of triclosan and E2 on the development of secondary sexual characters. These results do not support the hypothesis that triclosan is potently estrogenic. However, changes in fin length and non-significant trends in sex ratio suggest triclosan is potentially weakly androgenic.
Assuntos
Anti-Infecciosos Locais/toxicidade , Oryzias/metabolismo , Triclosan/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Estradiol/farmacologia , Feminino , Masculino , Fenótipo , Caracteres Sexuais , Razão de Masculinidade , Maturidade Sexual/efeitos dos fármacosRESUMO
Induction of vitellogenin (VTG) was compared among three teleostean species to determine their relative sensitivity of exposure to 17 beta-estradiol (E2). Japanese medaka (Oryzias latipes), sunshine bass (Morone saxatalis x Morone chrysops) and channel catfish (Ictalurus punctatus) were exposed to aqueous concentrations of E2 ranging from 10 to 100,000 ng/l for 21 days. Respective EC50 values for plasma VTG detected by western blot in medaka, catfish and bass were 200, 170 and 1560 ng E2/l. Since these EC50 values are based on VTG induction curves calculated relative to control values, they indicate differences in species' sensitivity to E2 exposure. Catfish and bass VTG responses obtained in laboratory exposures were compared to VTG responses previously observed with 21-day wastewater treatment plant effluent exposures. Plasma VTG induction in effluent-exposed fish ranged from 14 to 82% above reference values depending on species. Extrapolation of field responses with laboratory-exposed fish indicate catfish and bass were exposed to the equivalent of 27-240 ng E2/l in sewage effluent.
Assuntos
Bass/metabolismo , Estradiol/toxicidade , Ictaluridae/metabolismo , Oryzias/metabolismo , Vitelogeninas/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Western Blotting/veterinária , Relação Dose-Resposta a Droga , Estradiol/administração & dosagem , Técnicas Imunoenzimáticas/veterinária , MasculinoRESUMO
Medicinal plants may carry residuals of environmentally persistent pesticides or assimilate heavy metals in varying degrees. Several factors may influence contaminant accumulation, including species, level and duration of contaminant exposure, and topography. As part of a program for assessment of the quality of herbal medicines, we have analyzed 21 over-the-counter ginseng (Panax ginseng) products in various dosage forms. Chromium, mercury, and arsenic were undetectable above their limits of detection in both liquid and solid samples; while cadmium, lead, and nickel were present in the majority of samples. The chlorinated pesticide levels varied widely. In most samples, the total concentration of pesticides was below 100 ppb; while in 5 samples the total concentration exceeded 100 ppb.
Assuntos
Metais Pesados/análise , Panax/química , Praguicidas/análise , Plantas Medicinais/química , Arsênio/análise , Cádmio/análise , Cromo/análise , Poluentes Ambientais/análise , Hidrocarbonetos Clorados , Inseticidas/análise , Chumbo/análise , Mercúrio/análise , Níquel/análise , Espectrofotometria AtômicaRESUMO
The administration of prophylaxis against tetanus following a corneal abrasion is routinely performed in many acute care facilities, despite a lack of support in the literature for its necessity. The risk of developing clinical tetanus from three different types of injuries to the eye was evaluated in an animal model. Clinical tetanus was induced in unimmunized mice by injecting Clostridium tetani organisms or toxin into the anterior chamber. Immunized mice injected intracamerally did not develop signs of tetanus. Tetanus was not induced by topical inoculation of either live organisms or toxin following corneal epithelial debridement or stromal scarification of unimmunized and immunized mice. The results of this study support the administration of prophylaxis against tetanus following perforating ocular injuries. However, our results do not support its routine use following uncomplicated corneal abrasions or other types of nonperforating ocular injuries.
Assuntos
Lesões da Córnea , Ferimentos Oculares Penetrantes/complicações , Antitoxina Tetânica/uso terapêutico , Tétano/etiologia , Tétano/terapia , Animais , Contagem de Colônia Microbiana , Esquema de Medicação , Estudos de Avaliação como Assunto , Ferimentos Oculares Penetrantes/classificação , Camundongos , Camundongos Endogâmicos , Fatores de Risco , Tétano/microbiologia , Tétano/mortalidade , Tétano/patologia , Toxoide Tetânico/uso terapêuticoRESUMO
BACKGROUND/PURPOSE: In 1988, a report was published describing the histopathologic examination of corneal buttons of 4 patients who had undergone unilateral keratoplasty because of decreased vision caused by what had been diagnosed clinically as granular dystrophy. But on pathologic examination, lesions characteristic of both granular dystrophy and lattice dystrophy were found in each of the 4 corneal buttons. The patients came from 3 different families, each of which traced its origin to the Italian province of Avellino. We studied the clinical and histopathological features of 4 corneas affected by combined granular-lattice dystrophy, adding thereby to the total of 12 other corneas that have been so-described in the literature. METHODS: Two women underwent bilateral penetrating keratoplasty for what was diagnosed clinically as Reis-Bücklers dystrophy in the first patient, and as granular dystrophy in the second patient. We studied all 4 corneas pathologically, using both conventional hematoxylin and eosin stains as well as special histochemical techniques. RESULTS: All 4 corneas contained lesions characteristic of both granular dystrophy and lattice dystrophy, a circumstance that has given rise to the name "combined granular-lattice dystrophy." The patients are not known to be of Italian ancestry. CONCLUSIONS: Three clinical signs characterize combined granular-lattice dystrophy: (1) anterior stromal discrete, grayish-white deposits; (2) lattice lesions located in mid-stroma to posterior stroma; and (3) anterior stromal haze. Both clinically and histopathologically, the lattice lesions are of greater diameter than are those that occur in lattice dystrophy type I. In the past few years, striking advances have been made in understanding the genetics of combined granular-lattice dystrophy. The most recent of these was published just 2 months before the 1997 meeting of the American Ophthalmological Society, and establishes a common molecular origin for granular dystrophy, lattice dystrophy type I, Avellino dystrophy, and Reis-Bücklers dystrophy.
Assuntos
Córnea/patologia , Distrofias Hereditárias da Córnea/patologia , Idoso , Córnea/cirurgia , Distrofias Hereditárias da Córnea/cirurgia , Substância Própria/patologia , Feminino , Humanos , Ceratoplastia PenetranteRESUMO
A growing body of literature suggests a relationship between metals and a threatened health status among children, adolescents, and adults. Recently, several investigators have reported a direct link between exposure to metal and diminished affective, behavioral, and cognitive performance of school children. The purpose of the present study was to review and analyze methods and procedures used to understand the relationship between exposure to metals and cognitive, social, and motor functioning of school children.
Assuntos
Aprendizagem , Metais/efeitos adversos , Logro , Afeto , Criança , Comportamento Infantil , Pré-Escolar , Cognição , Humanos , Lactente , Recém-Nascido , Aprendizagem/efeitos dos fármacos , Metais/sangue , Metais/farmacologia , Destreza MotoraRESUMO
As part of the West Virginia Diabetes Eye Care Project of 1986, 178 patients in a rural diabetic population were screened for diabetic retinopathy using psychophysical testing and stereo fundus photography. The effects of sex, age, mode of therapy, and duration of diabetes mellitus on the prevalence of retinopathy were investigated. The prevalence of retinopathy was 34 per cent among insulin-treated patients, 18 per cent for those receiving oral hypoglycemics, and seven per cent for the diet-controlled group. Diabetic retinopathy was most prevalent among insulin-dependent patients with prolonged duration of disease. Age did not affect the prevalence of retinopathy after adjustment for sex and duration of diabetes.
Assuntos
Diabetes Mellitus/epidemiologia , Retinopatia Diabética/epidemiologia , População Rural , Diabetes Mellitus/prevenção & controle , Retinopatia Diabética/prevenção & controle , Feminino , Humanos , Masculino , Programas de Rastreamento , West VirginiaRESUMO
Acute and general medical care facilities are often faced with the challenge of diagnosing and managing problems related to the external eye. Making the correct diagnosis, possessing knowledge of the natural course of the disease, and understanding the potential benefits and risks of topical ocular therapy are necessary for the proper management of an acute or chronic red eye.