Fluoride increases lead concentrations in whole blood and in calcified tissues from lead-exposed rats

Higher blood lead (BPb) levels have been reported in children living in communities that receive fluoride-treated water. Here, we examined whether fluoride co-administered with lead increases BPb and lead concentrations in calcified tissues in Wistar rats exposed to this metal from the beginning of gestation. We exposed female rats and their offspring to control water (Control Group), 100 mg/L of fluoride (F Group), 30 mg/L of lead (Pb Group), or 100 mg/L of fluoride and 30 mg/L of lead (F+ Pb Group) from 1 week prior to mating until offspring was 81 days old. Blood and calcified tissues (enamel, dentine, and bone) were harvested at day 81 for lead and fluoride analyses. Higher BPb concentrations were found in the F+ Pb Group compared with the Pb Group (76.7 +/- 11.0 mu g/dL vs. 22.6 +/- 8.5 mu g/dL, respectively: p <0.001). Two-to threefold higher lead concentrations were found in the calcified tissues in the F+ Pb Group compared with the Pb Group (all p <0.001). Fluoride concentrations were similar in the F and in the F+ Pb Groups. These findings show that fluoride consistently increases BPb and calcified tissues Pb concentrations in animals exposed to low levels of lead and suggest that a biological effect not yet recognized may underlie the epidemiological association between increased BPb lead levels in children living in water-fluoridated communities. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Determination of total and inorganic mercury in whole blood by cold vapor inductively coupled plasma mass spectrometry (CV ICP-MS) with alkaline sample preparation

A simple method with a fast sample preparation procedure for total and inorganic mercury determinations in blood samples is proposed based on flow injection cold vapor inductively coupled plasma mass spectrometry (FI-CVICP-MS). Aliquots of whole blood (500 mL) are diluted 1 + 1 v/v with 10.0% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 3 h at room temperature and then further diluted 1 + 4 v/v with 2.0% v/v HCl. The inorganic Hg was released by online addition of L-cysteine and then reduced to elemental Hg by SnCl(2). On the other hand, total mercury was determined by on-line addition of KMnO(4) and then reduced to elemental Hg by NaBH(4). Samples were calibrated against matrix-matching. The method detection limit was found to be 0.80 mu g L(-1) and 0.08 mu g L(-1) for inorganic and total mercury, respectively. Sample throughput is 20 samples h(-1). The method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from the National Institute of Standards and Technology (NIST). For additional validation purposes, human whole blood samples were analyzed by the proposed method and by an established CV AAS method, with no statistical difference between the two techniques at 95% confidence level on applying the t-test.

Assessment of how pregnancy modifies plasma lead and plasma/whole blood lead ratio in ALAD 1-1 genotype women

Pregnant women are one of the most sensitive populations to the toxic effects associated with lead (Pb) exposure. These effects are primarily associated with plasma Pb (Pb-P), which reflects the most rapidly exchangeable fraction of Pb in the bloodstream, and elevated maternal Pb-P may be more relevant to foetal Pb exposure than whole blood Pb (Pb-B). We investigated how pregnancy affects Pb-B, Pb-P and %Pb-P/Pb-B ratios without the influence of the 6-aminolevulinic acid dehydratase (ALAD) G177C polymorphism, which is a major genetic factor influencing Pb-B, Pb-P and %Pb-P/Pb-B ratios. Genotypes for the ALAD G177C polymorphism were determined by PCR and restriction fragment length digestion in nine pregnant and 20 non-pregnant women, aged 18-33, environmentally exposed to Pb. Here, we included only women with ALAD 1-1 genotype. Pb-P and Pb-B were determined by inductively coupled plasma mass spectrometry and by graphite furnace atomic absorption spectrometry, respectively. We found no differences in Pb-B (P > 0.05). However, pregnant women had a 2-fold increase in Pb-P and a 3-fold increase in %Pb-P/Pb-B (both P < 0.01) compared to nonpregnant women. These alterations in Pb concentrations associated with pregnancy are similar to those associated with different ALAD gene variants. We can now better appreciate how pregnancy affects foetal exposure to Pb without the influence of this important genetic factor.

Mercury speciation in whole blood by gas chromatography coupled to ICP-MS with a fast microwave-assisted sample preparation procedure

A simple and fast method is described for simultaneous determination of methylmercury (MeHg), ethylmercury (Et-Hg) and inorganic mercury (Ino-Hg) in blood samples by using capillary gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) after derivatization and alkaline digestion. Closed-vessel microwave assisted digestion conditions with tetramethylammonium hydroxide (TMAH) have been optimized. Derivatization by using ethylation and propylation procedures have also been evaluated and compared. The absolute detection limits (using a 1 mu L injection) obtained by GC-ICP-MS with ethylation were 40 fg for MeHg and Ino-Hg, respectively, and with propylation were 50, 20 and 50 fg for MeHg, Et-Hg and Ino-Hg, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from the National Institute of Standards and Technology (NIST). Additional validation is provided based on the comparison of results obtained for mercury speciation in blood samples with the proposed procedure and with a previously reported LC-ICP-MS method. With the new proposed procedure no tedious clean-up steps are required and a considerable improvement of the time of analysis was achieved compared to other methods using GC separation.

Sensitivity to cisplatin-induced mutations and elevated chromosomal aberrations in lymphocytes from sickle cell disease patients

Sickle cell disease (SCD) is an inherited disorder caused by a single nucleotide substitution in the P-globin gene. The clinical heterogeneity observed in SCD patients has been attributed to environmental and genetic factors. The patients are subjected to increased oxidative stress, particularly during vaso-occlusive crises and acute chest pain. Another possible cause of oxidative stress in SCD is the high concentration of iron in the patients` plasma. The increase in oxidative stress could be a relevant risk factor for mutagenesis and carcinogenesis. Studies on the frequency of basal chromosomal aberrations in cultured lymphocytes from SCD patients have not been reported so far. In order to contribute to the understanding of the role of the different biomarkers and their relationship with the extremely variable clinical manifestation of SCD, we investigated the frequency of chromosome damage in peripheral lymphocytes from sickle cells patients and healthy controls. We found an increased frequency of chromosome damage and percentage of aberrant metaphases in these patients when compared with control subjects, even at basal values (p < 0.05). In the cytogenetic sensitivity assay, the results showed that these patients presented a marked decrease in the mitotic index values compared with healthy controls. Cisplatin-induced chromosomal damage in lymphocytes from these patients was significantly higher than the frequency measured in healthy controls. The results obtained in the present study showed that more investigations are needed in order to elucidate the susceptibility to genomic instability of SCD patients.

Cell cycle arrest evidence, parasiticidal and bactericidal properties induced by L-amino acid oxidase from Bothrops atrox snake venom

The present article describes an L-amino acid oxidase from Bothrops atrox snake venom as with antiprotozoal activities in Trypanosoma cruzi and in different species of Leishmania (Leishmania braziliensis, Leishmania donovani and Leishmania major). Leishmanicidal effects were inhibited by catalase, suggesting that they are mediated by H(2)O(2) production. Leishmania spp. cause a spectrum of diseases, ranging from self-healing ulcers to disseminated and often fatal infections, depending on the species involved and the host`s immune response. BatroxLAAO also displays bactericidal activity against both Gram-positive and Gram-negative bacteria. The apoptosis induced by BatroxLAAO on HL-60 cell lines and PBMC cells was determined by morphological cell evaluation using a mix of fluorescent dyes. As revealed by flow cytometry analysis, suppression of cell proliferation with BatroxLAAO was accompanied by the significant accumulation of cells in the G0/G1 phase boundary in HL-60 cells. BatroxLAAO at 25 mu g/mL and 50 mu g/mL blocked G0-G1 transition, resulting in G0/G1 phase cell cycle arrest, thereby delaying the progression of cells through S and G2/M phase in HL-60 cells. This was shown by an accentuated decrease in the proportion of cells in S phase, and the almost absence of G2/M phase cell population. BatroxLAAO is an interesting enzyme that provides a better understanding of the ophidian envenomation mechanism, and has biotechnological potential as a model for therapeutic agents. (C) 2011 Elsevier Masson SAS. All rights reserved.

The Ruthenium Complex cis-(Dichloro)tetraammineruthenium(III) Chloride Presents Selective Cytotoxicity Against Murine B Cell Lymphoma (A-20), Murine Ascitic Sarcoma 180 (S-180), Human Breast Adenocarcinoma (SK-BR-3), and Human T Cell Leukemia (Jurkat) Tumor Cell Lines

The aim of present study was to verify the in vitro antitumor activity of a ruthenium complex, cis-(dichloro)tetraammineruthenium(III) chloride (cis-[RuCl(2)(NH(3))(4)]Cl) toward different tumor cell lines. The antitumor studies showed that ruthenium(III) complex presents a relevant cytotoxic activity against murine B cell lymphoma (A-20), murine ascitic sarcoma 180 (S-180), human breast adenocarcinoma (SK-BR-3), and human T cell leukemia (Jurkat) cell lines and a very low cytotoxicity toward human peripheral blood mononuclear cells. The ruthenium(III) complex decreased the fraction of tumor cells in G0/G1 and/or G2-M phases, indicating that this compound may act on resting/early entering G0/G1 cells and/or precycling G2-M cells. The cytotoxic activity of a high concentration (2 mg mL(-1)) of cis-[RuCl(2)(NH(3))(4)]Cl toward Jurkat cells correlated with an increased number of annexin V-positive cells and also the presence of DNA fragmentation, suggesting that this compound induces apoptosis in tumor cells. The development of new antineoplastic medications demands adequate knowledge in order to avoid inefficient or toxic treatments. Thus, a mechanistic understanding of how metal complexes achieve their activities is crucial to their clinical success and to the rational design of new compounds with improved potency.

Influence of melatonin therapy and orchiectomy on T cell subsets in male Wistar rats infected with Trypanosoma cruzi

Gonadal steroids exert an important influence on the host immune response during infection. Changes resulting from the absence or replacement of gonadal hormones may represent a distinct evolution of a particular parasite. Taking into account the greater susceptibility of males to parasites, the magnitude of the immune response seems to depend on the interaction of many hormones that will act synergistically with other immune cells. The aims of this research were to evaluate the effects of the luck of male sex hormones due to orchiectomy, and the influence of oral administration of melatonin on the immune response of male Wistar rats infected with the Y strain of Trypanosoma cruzi. The percentage of CD3(+) CD4(+) and CD3(+) CD8(+) lymphocyte T cell subsets were evaluated using flow cytometry and the measurement of IL-2 and IL-12. For all parameters examined, a synergistic action of melatonin and orchiectomy on the host`s immune response was observed, promoting an effective response against the parasite during the acute phase of infection. These results offer insight into other possibilities for possibly controlling T. cruzi proliferation through melatonin therapy and also the stimulatory effects on host`s immune response triggered by the absence of male gonadal steroids during the acute phase of infection.

TLR2-dependent mast cell activation contributes to the control of Mycobacterium tuberculosis infection

Mast Cells (MCs) express toll-like receptor 2 (TLR2), a receptor known to be triggered by several major mycobacterial ligands and involved in resistance against Mycobacterium tuberculosis (MTB) infection. This study investigated whether adoptive transfer of TLR2 positive MCs (TLR2(+/+)) corrects the increased susceptibility of TLR2(-/-) mice to MTB infection. TLR2(-/-) mice displayed increased mycobacterial burden, diminished myeloid cell recruitment and proinflammatory cytokine production accompanied by defective granuloma formation. The reconstitution of these mice with TLR2(+/+) MCs, but not TLR2(-/-), confers better control of the infection, promotes the normalization of myeloid cell recruitment associated with reestablishment of the granuloma formation. In addition, adoptive transfer of TLR2(+/+) MC to TLR2(-/-) mice resulted in regulation of the pulmonary levels of IL-beta, IL-6, TNF-alpha, enhanced Th1 response and activated CD8(+) T cell homing to the lungs. Our results suggest that activation of MCs via TLR2 is required to compensate the defect in protective immunity and inability of TLR2(-/-) mice to control MTB infection. (C) 2009 Elsevier Masson SAS. All rights reserved.

A comparative study of similarity measures for manufacturing cell formation

We introduced a spectral clustering algorithm based on the bipartite graph model for the Manufacturing Cell Formation problem in [Oliveira S, Ribeiro JFF, Seok SC. A spectral clustering algorithm for manufacturing cell formation. Computers and Industrial Engineering. 2007 [submitted for publication]]. It constructs two similarity matrices; one for parts and one for machines. The algorithm executes a spectral clustering algorithm on each separately to find families of parts and cells of machines. The similarity measure in the approach utilized limited information between parts and between machines. This paper reviews several well-known similarity measures which have been used for Group Technology. Computational clustering results are compared by various performance measures. (C) 2008 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.

A spectral clustering algorithm for manufacturing cell formation

A graph clustering algorithm constructs groups of closely related parts and machines separately. After they are matched for the least intercell moves, a refining process runs on the initial cell formation to decrease the number of intercell moves. A simple modification of this main approach can deal with some practical constraints, such as the popular constraint of bounding the maximum number of machines in a cell. Our approach makes a big improvement in the computational time. More importantly, improvement is seen in the number of intercell moves when the computational results were compared with best known solutions from the literature. (C) 2009 Elsevier Ltd. All rights reserved.

Pt-RuO(2) electrodes prepared by thermal decomposition of polymeric precursors as catalysts for direct methanol fuel cell applications

The electrocatalytic activity of Pt and RuO(2) mixed electrodes of different compositions towards methanol oxidation was investigated. The catalysts were prepared by thermal decomposition of polymeric precursors and characterized by energy dispersive X-ray, scanning electronic microscopy, X-ray diffraction and cyclic voltammetry. This preparation method allowed obtaining uniform films with controlled stoichiometry and high surface area. Cyclic voltammetry experiments in the presence of methanol showed that mixed electrodes decreased the potential peak of methanol oxidation by approximately 100 mV (RHE) when compared to the electrode containing only Pt. In addition, voltammetric experiments indicated that the Pt(0.6)Ru(0.4)O(y) electrode led to higher oxidation current densities at lower potentials. Chronoamperometry experiments confirmed the contribution of RuO(2) to the catalytic activity as well as the better performance of the Pt(0.6)Ru(0.4)O(y) electrode composition. Formic acid and CO(2) were identified as being the reaction products formed in the electrolysis performed at 400 and 600 mV. The relative formation of CO(2) was favored in the electrolysis performed at 400 mV (RHE) with the Pt(0.6)Ru(0.4)O(y) electrode. The presence of RuO(2) in Pt-Ru-based electrodes is important for improving the catalytic activity towards methanol electrooxidation. Moreover, the thermal decomposition of polymeric precursors seems to be a promising route for the production of catalysts applicable to DMFC. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Development of novel bioanodes for ethanol biofuel cell using PAMAM dendrimers as matrix for enzyme immobilization

This paper describes the preparation and application of a novel bioanode for use in ethanol/O(2) biofuel cells based upon immobilization of alcohol dehydrogenase (ADH) and polyamidoamine (PAMAM) dendrimers onto carbon cloth platforms. The power density measurements indicated a direct relationship between the amount of anchored ADH and the anode power values, which increased upon enzyme loading. The power density values ranged from 0.04 to 0.28 mW cm(-2), and the highest power density was achieved with the bioanode prepared with 28 U of ADH, which provided a power density of 0.28 mW cm(-2) at 0.3 V. The latter power output values were the maximum observed, even for higher enzyme concentrations. Stability of the bioanodes was quite satisfactory, since there was no appreciable reduction of enzymatic activity during the measurements. The method of bioanode preparation described here has proven to be very effective. The PAMAM dendrimer represents a friendly environment for the immobilization of enzymes, and it is stable and capable of generating high power density compared to other immobilization methods. (C) 2010 Elsevier B.V. All rights reserved.

Improvement in Insulin Sensitivity and B-Cell Function Following Ileal Interposition with Sleeve Gastrectomy in Type 2 Diabetic Patients: Potential Mechanisms

Bariatric surgery in morbidly obese type 2 diabetic (T2DM) patients is associated with high rates of diabetes remission. We investigated the mechanisms of the anti-diabetic effect of the laparoscopic ileal interposition with sleeve gastrectomy (LII-SG) in normal weight (NW), overweight (OW) and obese (OB) T2DM patients. Ninety-four patients (aged 54 +/- 8 years) with long-standing (median 10 years), treated diabetes (median HbA(1c) = 8.6%), who were NW (15), OW (64) or OB (15) based on BMI, underwent LII-SG. Insulin sensitivity and parameters of -cell function were measured from an Oral Glycaemic Tolerance Test pre- and post-operatively. At a median of 13.4 months post-operatively, weight loss averaged 9.4 +/- 1.3, 16.8 +/- 0.8 and 23.2 +/- 1.7 kg in NW, OW and OB subjects, respectively (p < 0.0001). Insulin sensitivity was fully restored (395 [108] vs 208 [99] ml min(-1) m(-2)), fasting insulin secretion rate decreased (68 [52] vs 146 [120] pmol min(-1) m(-2)) and total insulin output increased (52 [26] vs 39 [28] nmol m(-2), all p a parts per thousand currency signaEuro parts per thousand 0.001). -cell glucose sensitivity doubled (37 [33] vs 18 [24] mol min(-1) m(-2) mM(-1), p < 0.0001). The only parameter predicting remission of diabetes was a lower baseline insulin sensitivity (p = 0.005). LII-SG induced changes on T2DM by mechanisms in part distinct from weight loss, principally involving restoration of insulin sensitivity and improvement of -cell function.

CLINICAL TUMOR DIMENSIONS MAY BE USEFUL TO PREVENT GEOGRAPHIC MISS IN CONVENTIONAL RADIOTHERAPY OF UTERINE CERVIX CANCER-A MAGNETIC RESONANCE IMAGING-BASED STUDY

Purpose: To evaluate the risk of geographic miss associated with the classic four-field ""box"" irradiation technique and to define the variables that predict this risk. Materials and Methods: The study population consisted of 80 patients with uterine cervix cancer seen between 2001 and 2006. Median age was 55 years (23-82 years), and 72 (90%) presented with squamous cell carcinoma. Most patients (68.7%) presented with locally advanced disease (IIb or more). Magnetic resonance imaging findings from before treatment were compared with findings from simulation of the conventional four-field ""box"" technique done with rectal contrast. Study variables included tumor volume; involvement of vagina, parametrium, bladder, or rectum; posterior displacement of the anterior rectal wall; and tumor anteroposterior diameter (APD). Margins were considered adequate when the target volume (primary tumor extension, whole uterine body, and parametrium) was included within the field limits and were at least 1 cm in width. Results: Field limits were inadequate in 45 (56%) patients: 29 (36%) patients at the anterior and 28 (35%) at the posterior border of the lateral fields. Of these, 12 patients had both anterior and posterior miss, and this risk was observed in all stages of the disease (p = 0.076). Posterior displacement of the anterior rectal wall beyond S2-S3 was significantly correlated with the risk of geographic miss (p = 0.043). Larger tumors (APD 6 cm or above and volume above 50 cm(3)) were also significantly correlated with this risk (p = 0.004 and p = 0.046, respectively). Conclusions: Posterior displacement of the anterior rectal wall, tumor APD, and volume can be used as guidance in evaluating the risk of geographic miss. (C) 2009 Elsevier Inc.