Synthesis, characterization, and application of modified silica in the removal and preconcentration of lead ions from natural river water

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Carbon-coated SnO2 nanobelts and nanoparticles by single catalytic step

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Validation of an HPLC Method for quantitative Determination of Benzocaine in PHBV-Microparticles and PLA-Nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Using the current Brazilian value for the biological exposure limit applied to blood lead level as a lead poisoning diagnostic criterion

Tradicionalmente, os limites de tolerância biológica são utilizados exclusivamente para a promoção e a preservação da saúde dos trabalhadores, não sendo aplicados com fins diagnósticos. Entretanto, com relação a algumas intoxicações profissionais, o assunto é polêmico. Neste artigo, defende-se a utilização do limite de tolerância aplicado atualmente no Brasil à plumbemia como um critério importante para a realização do diagnóstico da intoxicação profissional pelo chumbo. Argumenta-se que, em oposição ao tradicional critério clínico, deve-se abordar o problema do diagnóstico da intoxicação pelo chumbo sob um ponto de vista epidemiológico, utilizando-se o atual valor do limite de tolerância para a plumbemia como um marcador de risco relativo significativamente aumentado.

Silver nanoparticles: influence of stabilizing agent and diameter on antifungal activity against Candida albicans and Candida glabrata biofilms

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Silver Distribution and Release from an Antimicrobial Denture Base Resin Containing Silver Colloidal Nanoparticles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Tissue Reaction to Silver Nanoparticles Dispersion as an Alternative Irrigating Solution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of Candida albicans adhesion and biofilm formation on a denture base acrylic resin containing silver nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Deposition of Lead and Cadmium Released by Cigarette Smoke in Dental Structures and Resin Composite

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antioxidant defense in rat brain regions after developmental lead exposure

Oxidative stress is considered a possible molecular mechanism involved in Pb neurotoxicity. Considering the vulnerability of the developing brain to Pb neurotoxicity, this study was carried out to investigate the effects of low-level developmental Pb exposure on brain regions antioxidant enzymes activities. Wister dams were exposed to 500 ppm of Pb, as Pb acetate, or to 660 ppm Na acetate in the drinking water during pregnancy and lactation. The activities of superoxide dismutase (SOD), glutathione peroxidase and glutathione reductase were determined in the hypothalamus, hippocampus and striatum of male pups at 23 (weaned) or 70 days (adult) of age. In the Pb-exposed 23-day-old pups, the activity of SOD was decreased in the hypothalamus. Regarding adults, there was no significant treatment effect in any of the enzymes and regions evaluated. Based on the present results, it seems that oxidative stress due to decreased antioxidant function may occur in weaned rats but it is suggested that this should not be the main mechanism involved in the neurotoxicity of low-level Pb exposure. (C) 2001 Elsevier B.V. Ireland Ltd. All rights reserved.

Perinatal lead exposure affects nitric oxide and cyclooxygenase pathways in aorta of weaned rats

Perinatal Pb exposure may modulate arterial tone through nitric oxide (NO) and cyclooxygenase products. To investigate this, Wistar dams received 1000 ppm of Pb or sodium acetate (control) in drinking water during pregnancy and lactation. Curves were constructed in phenylephrine-precontracted intact and/or denuded rings of thoracic aortas of weaned (23-day-old) male pups from their responses to N-omega-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and ACh in the absence or presence of indomethacin (10(-5)M, cyclooxygenase inhibitor) or L-NAME (3 x 10(-7)M and 3 x 10(-4)M). Blood lead concentration and systolic blood pressure (SBP) were higher in intoxicated than control pups (blood lead mu g/dl: control < 3.0, Pb 58.7 +/- 6.5*; SBP mmHg: control 111.4 +/- 2.3, Pb 135.5 +/- 2.4*). In L-NAME-treated rings maximal responses increased in Pb-exposed rats, and were higher in intact than in denuded aortas (contraction [% of phenylephrine] intact: control 184.3 +/- 23.7, Pb 289.1 +/- 18.3*; denuded: control 125.1 +/- 4.5, Pb 154.8 +/- 13.3*). ACh-induced relaxation in intact aortas from Pb-exposed rats presented rightward shift in L-NAME presence (EC50 x 10(-7)M: control 1.32 [0.33-5.18], Pb 4.88 [3.56-6.69]*) but moved left under indomethacin (EC50 x 10(-7)M: control 8.95 [3.47-23.07], Pb 0.97 [0.38-2.43]*). *p < 0.05 significant relative to the respective control; N = 7-9. Endothelium removal abolished ACh-induced relaxation. Perinatal Pb exposure caused hypertension associated with alterations in the production and/or release of basal and stimulated endothelium-derived relaxing factors-NO and constricting cyclooxygenase products. These findings may help explain the contribution of NO and cyclooxygenase products to the etiology and/or maintenance of Pb-induced hypertension and could ultimately lead to therapeutic advantages in plumbism.

Determination of lead in the absence of supporting electrolyte using carbon fiber ultramicroelectrode without mercury film

The determination of lead ions directly in water, for application in analysis of samples of environmental interest, was studied by electroanalytical techniques. Linear sweep anodic stripping voltammetry with a carbon fiber disk ultramicroelectrode (7.0 mu m in diameter), without mercury film, has been used for lead determination, by standard addition, in purified water in the absence of supporting electrolyte. The response was linear in the range from 10.0 to 50.0 mu g L-1, with a detection limit of 0.8 mu g L-1, for 300 s preconcentration time, at -1.2 V and 1.0 V s(-1) scan rate. The reliability of the analytical procedure was evaluated by precision using relative standard deviations (5.6%, for three repetitive stripping current measurements of solution with 10.0 mu g L-1 lead ions) and by the accuracy with recovery experiments (mean of 110.8%) for the same concentration.