992 resultados para Lead (Pb) toxicity


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pelagic clay of the east-central Pacific province is shown to be a mixture of three primary detrital components, reflecting continental source areas in Asia, North America, and Central and South America. Relative contributions from each source area are a function of geography, and this distribution appears to have remained constant over the past five million years, despite changing flux rates. A Q-mode factor analysis of downcore records for Pb, Sr, and Nd isotopes identified three factors that account for 98% of the total variance. These factors represent the radiogenic isotopic signatures of 1) late Cenozoic Asian dust, which dominates in the central North Pacific; 2) North American continental hemipelagic/eolian sources, restricted mainly to the easternmost North Pacific at ~30 °N latitude; and 3) Central and South American sources, restricted to areas east of ~100 °W longitude. South of the Intertropical Convergence Zone (~6 °N), the Asian dust signature diminishes abruptly. We conclude that late Cenozoic Asian dust sources can be isotopically differentiated downcore from both North American and South and Central American sources in the eastcentral Pacific. This approach has a utility for identifying changes in long-term Cenozoic atmospheric circulation patterns.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The article covers basic inorganic chemistry of lead. As an introduction, the properties and historical uses of metallic lead are discussed, followed by aspects of lead toxicity, including the toxicity origins and effects of lead poisoning. Properties of lead as a heavy p-block element are discussed, with emphasis on the modern view of the so-called “inert pair effect”, including its origin, the influence on stability of lead oxidation states, and on the coordination chemistry of lead(II), viz., “sterically active lone pair”. This is followed by an overview of lead inorganic compounds, including halides, pseudohalides, oxides and chalcogenides, hydroxides and their chalcogenide analogs, alkoxides, oxoacids, O-donors, S- and Se-donors, Group 15 donors, compounds with lead-transition metal bonds, and finally metallic clusters (Zintl phases). This is by no means a comprehensive review, rather compounds representative for each class were presented. In most sections, structural aspects of each class of compounds are discussed, followed by applications, with the focus on modern uses in material science.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The main objective of the study about the citizenship development in elderly attended by the Conviver Program of the City Hall of Campina Grande in Paraiba, Brazil was to evaluate how the actions of the Program contribute for the citizenship practice according to the users. The Citizenship analyzed is the existence of political, civil and social rights according to Marshall. For that it was utilized a descriptive research and a study of case based on technical procedure. The research was settled by the people who are benefited by the Conviver Program of the Snow Hair Group and the sample was formed by the active participants that it is in the Group for over ten years, corresponding to a total of ten elderly. For the data collection was utilized basic questionnaire in function of the low schooling of the interviewed, according to Marshall (2002) theory about the citizenship construction from each person. It was utilized the methodological procedure proposed by Bardin (2006), categorical analysis, in the qualitative data analysis, that was divided in four parts. In relation to Political Rights, noted that the program has stimulated your Watched on the exercise of voting and being voted. On the Civil Rights was observed that the Program has given incentive to actions which provide the users the justice rights in and in occupational activities as a job. In relation to Social Rights it was observed that the Conviver Program has contributed in order that its users can lead their lives according to the standards imposed by the society, which have being failed in the education area. As for the type of citizenship it was verified that the Program has given incentive to the served users, becoming more evidence on the speech basis

Relevância:

30.00% 30.00%

Publicador:

Resumo:

L’irinotécan est un agent de chimiothérapie largement utilisé pour le traitement de tumeurs solides, particulièrement pour le cancer colorectal métastatique (mCRC). Fréquemment, le traitement par l’irinotécan conduit à la neutropénie et la diarrhée, des effets secondaires sévères qui peuvent limiter la poursuite du traitement et la qualité de vie des patients. Plusieurs études pharmacogénomiques ont évalué les risques associés à la chimiothérapie à base d’irinotécan, en particulier en lien avec le gène UGT1A, alors que peu d’études ont examiné l’impact des gènes codant pour des transporteurs. Par exemple, le marqueur UGT1A1*28 a été associé à une augmentation de 2 fois du risque de neutropénie, mais ce marqueur ne permet pas de prédire la toxicité gastrointestinale ou l’issue clinique. L’objectif de cette étude était de découvrir de nouveaux marqueurs génétiques associés au risque de toxicité induite par l’irinotécan, en utilisant une stratégie d’haplotype/SNP-étiquette permettant de maximiser la couverture des loci génétiques ciblés. Nous avons analysé les associations génétiques des loci UGT1 et sept gènes codants pour des transporteurs ABC impliqués dans la pharmacocinétique de l’irinotécan, soient ABCB1, ABCC1, ABCC2, ABCC5, ABCG1, ABCG2 ainsi que SLCO1B1. Les profils de 167 patients canadiens atteints de mCRC sous traitement FOLFIRI (à base d’irinotécan) ont été examinés et les marqueurs significatifs ont par la suite été validés dans une cohorte indépendante de 250 patients italiens. Nous avons découvert dans la région intergénique en aval du gène UGT1, un nouveau marqueur (rs11563250G) associé à un moindre risque de neutropénie sévère (rapport des cotes (RC)=0.21; p=0.043 chez les canadiens, RC=0.27; p=0.036 chez les italiens, et RC=0.31 p=0.001 pour les deux cohortes combinées). De plus, le RC est demeuré significatif après correction pour multiples comparaisons (p=0.041). Par ailleurs, pour l’haplotype défini par les marqueurs rs11563250G et UGT1A1*1 (rs8175347 TA6), le RC était de 0.17 (p=0.0004). Un test génétique évaluant ces marqueurs permettrait d’identifier les patients susceptibles de bénéficier d’une augmentation de dose d’irinotécan. En revanche, une autre combinaison de marqueurs, ABCC5 rs3749438 et rs10937158 (T–C), a prédit un risque plus faible de diarrhée sévère dans les deux cohortes (RC = 0.43; p=0.001). La coexistence des marqueurs ABCG1 rs225440T et ABCC5 rs2292997A a prédit un risque accru de neutropénie (RC=5.93; p=0.0002), alors qu’une prédiction encore plus significative a été obtenue lorsque ces marqueurs sont combinés au marqueur de risque bien établi UGT1A1*28 rs8175347 (RC=7.68; p<0.0001). Enfin, les porteurs de l’allèle de protection UGT1 rs11563250G en absence d’allèles de risque, ont montré une incidence réduite de neutropénie sévère (8.2% vs. 34.0%; p<0.0001). Nous concluons que ces nouveaux marqueurs génétiques prédictifs pourraient permettre d’améliorer l’évaluation du risque de toxicité et personnaliser le traitement à base d’irinotécan pour les patients atteints du cancer colorectal métastatique.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Hydroxychloroquine is an antimalarial drug used in many rheumatologic and systemic diseases. Although considered by clinicians to be relatively safe, serious side effects have been documented (retinotoxicity, neuromyotoxicity and cardiotoxicity). We present the case of a 41-year-old woman with systemic lupus erythematosus (SLE) who presented at our institution with acute heart failure after taking hydroxychloroquine for a period of 3 months. An endomyocardial biopsy ruled out myocarditis related to systemic lupus erythematosus but demonstrated pathological changes related to hydroxychloroquine toxicity. It is exceptional to observe such cardiac toxicity after such a low cumulative dose (16 grams). The potential severity and reversibility of this complication underscores the importance of a high level of suspicion and timely diagnosis.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Heavily contaminated sediments are a serious concern for ecosystem quality, especially in coastal areas, where vulnerability is high due to intense anthropogenic pressure. Surface sediments (54 stations), 50 cm interface cores (five specific stations), river particles, coal and bulk Pb plate from past French Navy activities, seawater and mussels were collected in Toulon Bay (NW Mediterranean Sea). Lead content and Pb stable isotope composition have evidenced the direct impact of sediment pollution stock on both the water column quality and the living organisms, through the specific Pb isotopic signature in these considered compartments. The history of pollution events including past and present contaminant dispersion in Toulon Bay were also demonstrated by historical records of Pb content and Pb isotope ratios in sediment profiles. The sediment resuspension events, as simulated by batch experiments, could be a major factor contributing to the high Pb mobility in the considered ecosystem. A survey of Pb concentrations in surface seawater at 40 stations has revealed poor seawater quality, affecting both the dissolved fraction and suspended particles and points to marina/harbors as additional diffuse sources of dissolved Pb.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

There are various tools for monitoring the concentration of pollutants on aquatic ecosystems. Today these studies are based on biological monitoring and biomarkers. The aim of this study was to measure the concentration of the acetylcholinesterase (AChE), glutathione S-transferase and catalase as biomarkers of heavy metal contamination in pearl oyster Pinctada radiata and their mechanism in aquatic ecosystems. Heavy metals lead, cadmium and nickel were measured in soft tissue and studied stations in four seasons. Samples were collected seasonally in Lavan stations, Hendurabi and Nakhilo (in the northern Persian Gulf) from spring 2013 to winter of that year by scuba diving. Pearl oysters are divided according to their shells size; shells separated from soft tissues and were transferred to the laboratory for analysis of heavy metals and enzymes. Moopam standard method for were used for measuring the concentration of heavy metals and for analyzing tissue concentrations of glutathione S-transferase in Clam the method recommended by Habig et al in 1974 were used. For measuring acetylcholinesterase Ellman method were used. Catalase contamination in pearl oyster in the supernatant obtained from the study based on the method homogeate soft tissue of mussels (Abei, 1974) was evaluated. The results showed that the concentration of lead has significant difference in sediments station, the concentration of lead in Lavan is significantly higher than the other two stations, This could be due to the movement of tanker, boats and floating refueling and with a considerable amount of wastewater containing oil and Petroleum into the water, and also due to precipitation and industrial discharges the lead in the region is increasing, land-disposed sewage sludge, has large concentrations of lead. Compare the results of this study with standards related and other similar studies at the regional and international level showed that pollutant concentration of heavy metals in all cases significantly less than all the standards and guide values associated. And also compared to other world research results have been far less than others, Being Less of the conclusion given in this research according that nickel is one of the indicators of oil pollution in the study area and emissions have been relatively low of oil. The concentration of acetylcholinesterase at several stations, in large and small sizes and in the seasons had no significant difference. Variations of catalase, and glutathione S-transferase were almost similar to each other and parameters, station and seasons were significantly different in the concentrations of these enzymes. The effects and interaction between various parameters indicate that following parameters has impact on the concentration of catalase and glutathione S-transferase. Stations; Seasonal changes in antioxidant enzymes related to (assuming a constant in salinity and oxygen) to age, reproductive cycle, availability of food and water temperature. With increasing temperature at warm season, antioxidant enzymes were increase, with increasing temperature and abundance of food in the environment the amount of antioxidant enzymes may increase. The presence of the enzyme concentration may indicate that the higher levels of the enzyme to eliminate ROS activities to be any healthier situation. At the time of gonads maturation and spawning season catalase activity increases. This study also indicates that catalase was significantly higher in the warm season. Due to low pollutants of heavy metals in the study area, a lower level of contaminants were observed in shellfish tissue incidents of international standards and strong correlation between the amount of heavy metal contamination in pearl oyster tissue and enzymes was not observed. Therefore, we can say that the pearl oyster remains in a healthy condition and the amount of enzyme is normal.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Chitosan is a natural polymer obtained by deacetylation of chitin. After cellulose chitin is the second most abundant polysaccharide in nature. It is biologically safe, non-toxic, biocompatible and biodegradable polysaccharide. Chitosan loaded with zinc oxide nanoparticles have gained more attention bio sorbent because of their better stability, low toxicity, simple and mild preparation method and high sorption capacity. Chitosan loaded with zinc oxide nanoparticles have been prepared of chitosan. The physicochemical properties of nanoparticles were characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM) Analysis. Its sorption capacity for lead and cadmium ions studied. Factors such as initial concentration of lead ions, cadmium ions sorbent amount, contact time, pH and temperature were investigated. It is found that chitosan loaded with zinc oxide nanoparticles could sorb lead and cadmium ions effectively, this sorption rate was affected significantly by initial concentration of lead and cadmium ions, sorbent amount, contact time, pH of solution. The maximum of percentage of lead sorption was 98 % with initial concentration 3 mg/l and sorbent amount 0.05 g, pH 11 in 45 min and cadmiumwas90 %with initial concentration 3mg/l and sorbent amount 0.05 g, pH 11 in45 min. Consequently chitosan loaded with zinc oxide nanoparticles demonstrated greater fixation ability for lead ions than cadmium ions.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The main objective of the study about the citizenship development in elderly attended by the Conviver Program of the City Hall of Campina Grande in Paraiba, Brazil was to evaluate how the actions of the Program contribute for the citizenship practice according to the users. The Citizenship analyzed is the existence of political, civil and social rights according to Marshall. For that it was utilized a descriptive research and a study of case based on technical procedure. The research was settled by the people who are benefited by the Conviver Program of the Snow Hair Group and the sample was formed by the active participants that it is in the Group for over ten years, corresponding to a total of ten elderly. For the data collection was utilized basic questionnaire in function of the low schooling of the interviewed, according to Marshall (2002) theory about the citizenship construction from each person. It was utilized the methodological procedure proposed by Bardin (2006), categorical analysis, in the qualitative data analysis, that was divided in four parts. In relation to Political Rights, noted that the program has stimulated your Watched on the exercise of voting and being voted. On the Civil Rights was observed that the Program has given incentive to actions which provide the users the justice rights in and in occupational activities as a job. In relation to Social Rights it was observed that the Conviver Program has contributed in order that its users can lead their lives according to the standards imposed by the society, which have being failed in the education area. As for the type of citizenship it was verified that the Program has given incentive to the served users, becoming more evidence on the speech basis

Relevância:

30.00% 30.00%

Publicador:

Resumo:

To determine the ameliorative effect of coconut water on haematobiochemical changes due to lead poisoning in wistar albino rats for six weeks, sixty rats were assigned to four groups. 0.10g/l of lead and 75ml coconut ( cocus nucifera l.) water were given orally for six weeks. The mean values of red blood cells, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red blood cell distribution width and platelets (8.10±0.63(×106μl), 52.7±0.87(μm3), 17.9±0.56(pg), 34.73±0.65(g/dl), 17.90±0.67(%) and 670.00±42.22(×103μl) respectively) reduced in lead treated rats when compared with control mean values (8.41 ± 0.90(×106μl), 56.60 ± 1.55(μm3), 19.33 ± 0.82(pg), 34.93 ± 0.90(g/dl), 18.27 ± 0.73(%) and 818.33± 123.68(×103μl) respectively ) and these values increased in75ml coconut water only group and the group of 0.10g/l lead + 75ml coconut water except mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, and red blood cell distribution width of the 75ml coconut water only. The mean values of white blood cells, lymphocytes, total cholesterol, triglyceride, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol, low density lipoprotein-cholesterol/high density lipoproteincholesterol and total cholesterol/high density lipoprotein-cholesterol increased (12.23±0.57(×103μl), 79.83±3.87(%), 64.66±6.01(mg/dl), 89.00±7.94(mg/dl), 22.67±6.93(mg/dl), 21.00±4.58(mg/dl), 1.29±0.62 and 3.36±0.83 respectively ) in the lead group when compared with mean values of control group (5.83±0.74(×103μl), 69.07±10.57(%), 54.00±4.04(mg/dl), 97.33±11.34(mg/dl), 20.00±3.06(mg/dl), 17.00±6.51(mg/dl), 0.97±0.41 and 2.87±0.55 respectively) but the mean values decreased when compared with the mean values of group of 75ml coconut water only and group of 0.10g/l lead + 75ml coconut water, except the mean values of high density lipoprotein-cholesterol. These results indicate that coconut water could ameliorate effects of lead toxicity