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Toxic Elements (toxic + element)
Selected AbstractsTreg-Therapy Allows Mixed Chimerism and Transplantation Tolerance Without Cytoreductive ConditioningAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2010N. Pilat Establishment of mixed chimerism through transplantation of allogeneic donor bone marrow (BM) into sufficiently conditioned recipients is an effective experimental approach for the induction of transplantation tolerance. Clinical translation, however, is impeded by the lack of feasible protocols devoid of cytoreductive conditioning (i.e. irradiation and cytotoxic drugs/mAbs). The therapeutic application of regulatory T cells (Tregs) prolongs allograft survival in experimental models, but appears insufficient to induce robust tolerance on its own. We thus investigated whether mixed chimerism and tolerance could be realized without the need for cytoreductive treatment by combining Treg therapy with BM transplantation (BMT). Polyclonal recipient Tregs were cotransplanted with a moderate dose of fully mismatched allogeneic donor BM into recipients conditioned solely with short-course costimulation blockade and rapamycin. This combination treatment led to long-term multilineage chimerism and donor-specific skin graft tolerance. Chimeras also developed humoral and in vitro tolerance. Both deletional and nondeletional mechanisms contributed to maintenance of tolerance. All tested populations of polyclonal Tregs (FoxP3-transduced Tregs, natural Tregs and TGF-, induced Tregs) were effective in this setting. Thus, Treg therapy achieves mixed chimerism and tolerance without cytoreductive recipient treatment, thereby eliminating a major toxic element impeding clinical translation of this approach. [source] Emission of trace toxic metals during pulverized fuel combustion of Czech coalsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2003P. Danihelka Abstract A study of the trace elements emission (As, Se, Cd, Co, Cr, Cu, Zn, Hg, Tl, Pb, Ni, Sn, Sb, V, Mn and Fe) from pulverized coal combustion has been made at six heating and power stations situated in the Czech Republic. The amount of chlorine in coal has considerable influence on volatilization of some elements such as Zn, Cu, Pb, Hg and Tl, which is explained by the formation of thermodynamically stable compounds of these elements with chlorine. Generally, the affinities for Cl follows the order Tl > Cu > Zn > Pb > Co > Mn > Sn > Hg. The experimental data indicates enrichment of some of the trace toxic elements in the emissions (Cu, Zn, As, Se, Cd, Sn, Sb, Hg and Pb) and good agreement was obtained by thermodynamic equilibrium calculations with a few exceptions. In the case of Fe, Mn, Co, Cr and Sn calculated values are overestimated in the bottom ash and there are zero predicted amounts of these elements in the fly ash. In comparison, the results from experiments show up to 80% of these elements retained in fly ash. This implies that there exist additional steps leading to the enrichment by Fe, Mn, Co, Cr and Sn of small particles. Such mechanisms could include the ejection during devolatilization of small inorganic particles from the coal of bottom ash particles, or disintegration of the char containing these metals to small particles of fly ash. On the other hand, there are slightly overestimated or similar values of relative enrichment factors for As, V, Cu, Cd, Sb, Tl and Pb in the fly ashes and zero predicted values for bottom ashes. Our experimental results show about 5% or less of these elements are retained in bottom ashes, so they probably remain in the bottom ash inside unburned parts of coal. Copyright © 2003 John Wiley & Sons, Ltd. [source] Chemical composition and toxic trace element composition of some Nigerian edible wild mushroomsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2008Olumuyiwa S. Falade Summary Two essential amino acids (methionine and tryptophan); anti-nutritional factors (tannin and trypsin inhibitor) and toxic elements (Pb, Cd, Ni, As, Hg and Cr) were determined spectrophotometrically from five edible wild mushrooms. The tryptophan content was between 1.00 and 1.82 g (100 g),1 but methionine was low at 0.26,1.38 g (100 g),1. Tannin content was high (30.3,40.0 mg g,1) but trypsin inhibitor was low (22.0,39.5 TIU g,1). Trace elements analysis reviled Pb (0.34,5.06 mg kg,1) to be the highest of all the trace elements. Cd was (0.06,1.70 mg kg,1), Ni (0.26,2.08 mg kg,1), As (0.17,0.92 mg kg,1), Hg (0.01,0.05 mg kg,1) and Cr (0.04,0.22 mg kg,1). These mushrooms are nutritious but must be well processed to eliminate or at least reduce the levels of tannin and Pb to improve their nutritional values. [source] Synanthropic primates in Asia: Potential sentinels for environmental toxinsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Gregory Engel Abstract Macaques are similar to humans both physiologically and behaviorally. In South and Southeast Asia they are also synanthropic, ecologically associated with humans. Synanthropy with humans raises the possibility that macaques come into contact with anthropogenic toxicants, such as lead and mercury, and might be appropriate sentinels for human exposures to certain toxic materials. We measured lead (Pb) and mercury (Hg) levels and characterized the stable isotopic compositions of ,15N and ,13C in hair from three groups of free-ranging macaques at the Swoyambhu temple in Kathmandhu, Nepal, an urban population that has abundant contact with humans. Hair lead levels were significantly higher among young macaques and differed among the three groups of macaques that were sampled. Hair Hg levels were low. No statistical association was found between stable isotopic compositions (,15N and ,13C) and Pb and Hg levels. Our data did not find evidence that lead levels were associated with diet. We conclude that, in this population of macaques, behavioral and/or physiologic factors may play a significant role in determining exposure to lead. Chemical analysis of hair is a promising, noninvasive technique for determining exposure to toxic elements in free-ranging nonhuman primates. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Speciation of essential and toxic elements in edible mushrooms: size-exclusion chromatography separation with on-line UV,inductively coupled plasma mass spectrometry detectionAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2004Rodolfo G. Wuilloud Abstract Size-exclusion liquid chromatography was coupled to UV and inductively coupled plasma mass spectrometry (ICP-MS) for detection to perform elemental speciation studies on different edible mushrooms. Molecular weight (MW) distribution patterns of several elements among different fractions present in various edible mushrooms are presented. The association of the elements with the high and low MW fractions was observed using sequential detection by UV and ICP-MS. Separation was performed using a Superdex 75 column. Variability of the fractionation patterns with three different extraction media (0.05 mol l,1 NaOH; 0.05 mol l,1 HCl; hot water at 60°C) was evaluated for mushroom species. A comparative elemental speciation study was performed in order to determine the differences in the fractionation patterns of silver, arsenic, cadmium, mercury, lead, and tin in Boletus edulis, Agaricus bisporus, and Lentinus edodes. Differences in the fractionation patterns of the elements were found to depend on the mushroom species and the extraction medium. Most of the elements were associated with high mw fractions. It was not possible to assess the trace metal contributions from the mushroom growth media. Copyright © 2004 John Wiley & Sons, Ltd. [source] Natural revegetation of coal fly ash in a highly saline disposal lagoon in Hong KongAPPLIED VEGETATION SCIENCE, Issue 3 2008L.M. Chu Abstract. Question: What is the relationship of the naturally colonizing vegetation and substrate characteristics in fly ash lagoons? Location: West lagoon, Deep Bay, a 13-ha coastal lagoon in Hong Kong in subtropical Southeast Asia. Methods: Vegetation establishment was examined in a coal fly ash lagoon two years after its abandonment to investigate the distribution of vegetation in relationship to the chemical properties of the fly ash in the lagoon. A greenhouse experiment assessed the limits imposed on plant growth in fly ash. Results: The fly ash was saline, slightly alkaline and very poor in organic matter and nitrogen. Ash from bare and vegetated areas differed significantly in their salinity and extractable concentrations of inorganic nitrogen and various metals. Bare ash had a significantly higher conductivity and extractable sodium, aluminum, manganese, potassium, and lead. In total 11 plant species that belonged to seven families were found growing on the fly ash; all species except the shrub Tamarix chinensis were herbaceous. Using discriminant analysis, the most important factors in distinguishing bare and vegetated ashes were conductivity and sodium. Cluster analysis of bare samples gave two distinct groups, one from the periphery of the lagoon, which had lower sodium, conductivity, organic carbon, potassium and copper, and the other from a second group that contained ashes from the central region of the lagoon. Results of the greenhouse experiment showed that the inhibition of plant growth was significantly correlated with the presence of soluble toxic elements in ash. Conclusion: Toxicity and salinity seem to be the major limiting factors to plant establishment in fly ash, and these factors must be ameliorated for the successful reclamation of these fly ash lagoons. [source] | ||||||||||