Zinc does not inhibit prolactin secretion during insulin-induced hypoglycemia in normal men

Zinc (Zn ++) has been shown as an important physiological inhibitor of pituitary PRL release, and Zn ++ and PRL could be involved in a negative feedback regulatory loop. However, this inhibitory effect has not been detected in humans with regard to thyrotropin releasing hormone (TRH), dopamine (DA) and histamine (HA) neurotransmitters. In order to investigate this topic, Zn ++ was acutely and chronically administered to five healthy men to observe the probable inhibitory effect on PRL release during insulin-induced hypoglycemia. The positive PRL response to hypoglycemia has generally been considered to be mediated via the hypothalamus by adrenergic, serotoninergic, histaminergic, opioid-peptidergic and TRH neurotransmitters. The results showed that Zn ++ was not able to inhibit the PRL release during insulin-induced hypoglycemia. Under these conditions, Zn ++ does not block hypothalamic neurotransmitters stimulated by hypoglycemia, thus excluding its clinical application in human beings. On the other hand, the effect of acute stress, such as hypoglycemia, on the serum Zn ++ profile was not observed. ©2006 Dustri-Verlag Dr. K. Feistle.

Comparative studies of the sample decomposition of green and roasted coffee for determination of nutrients and data exploratory analysis

The contents of some nutrients in 35 Brazilian green and roasted coffee samples were determined by flame atomic absorption spectrometry (Ca, Mg, Fe, Cu, Mn, and Zn), flame atomic emission photometry (Na and K) and Kjeldahl (N) after preparing the samples by wet digestion procedures using i) a digester heating block and ii) a conventional microwave oven system with pressure and temperature control. The accuracy of the procedures was checked using three standard reference materials (National Institute of Standards and Technology, SRM 1573a Tomato Leaves, SRM 1547 Peach Leaves, SRM 1570a Trace Elements in Spinach). Analysis of data after application of t-test showed that results obtained by microwave-assisted digestion were more accurate than those obtained by block digester at 95% confidence level. Additionally to better accuracy, other favorable characteristics found were lower analytical blanks, lower reagent consumption, and shorter digestion time. Exploratory analysis of results using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that Na, K, Ca, Cu, Mg, and Fe were the principal elements to discriminate between green and roasted coffee samples. ©2007 Sociedade Brasileira de Química.

Concentrations of Cu, Fe, Mn, and Zn in tropical soils amended with sewage sludge and composted sewage sludge

Sewage sludge may be used as an agricultural fertilizer, but the practice has been criticized because sludge may contain trace elements and pathogens. The aim of this study was to compare the effectiveness of total and pseudototal extractants of Cu, Fe, Mn, and Zn, and to compare the results with the bioavailable concentrations of these elements to maize and sugarcane in a soil that was amended with sewage sludge for 13 consecutive years and in a separate soil that was amended a single time with sewage sludge and composted sewage sludge. The 13-year amendment experiment involved 3 rates of sludge (5, 10, and 20 t ha-1). The one-time amendment experiment involved treatments reflecting 50, 100, and 200 % of values stipulated by current legislation. The metal concentrations extracted by aqua regia (AR) were more similar to those obtained by Environmental Protection Agency (EPA) 3052 than to those obtained by EPA3051, and the strongest correlation was observed between pseudo(total) concentrations extracted by AR and EPA3052 and bioavailable concentrations obtained by Mehlich III. An effect of sewage sludge amendment on the concentrations of heavy metals was only observed in samples from the 13-year experiment. © 2012 Springer Science+Business Media B.V.

Testing extractants for Cu, Fe, Mn, and Zn in tropical soils treated with sewage sludge for 13 consecutive years

In this paper, we report on a field experiment being carried out in a Typic Eutrorthox. The experiment was initiated in the 1997-98 agricultural season as a randomized block design with four treatments (0, 5, 10, and 20 t ha -1) of sewage sludge and five replicates. Compound soil samples were obtained from 20 subsamples collected at depths of 0-0.1 and 0.1-0.2 m. Cu, Fe, Mn, and Zn concentrations were extracted with DTPA pH 7.3; 0.1 mol L -1 HCl, Mehlich-I, Mehlich-III, and 0.01 mol L-1 CaCl 2. Metal concentrations were determined via atomic absorption spectrometry. Diagnostic leaves and the whole above-ground portion of plants were collected to determine Cu, Fe, Mn, and Zn concentrations extracted by nitric-perchloric digestion and later determined via atomic absorption spectrometry. Sewage sludge application caused increases in the concentrations of soil Cu, Fe, and Mn in samples taken from the 0-0.1 m depth evaluated by the extractants Mehlich-I, Mehlich-III, 0.01 mol L-1 HCl and DTPA pH 7.3. None of the extractants provided efficient estimates of changes in Mn concentrations. The acid extractants extracted more Cu, Fe, Mn, and Zn than the saline and chelating solutions. The highest concentrations of Cu, Fe, and Zn were obtained with Mehlich-III, while the highest concentrations of Mn were obtained with HCl. We did not observe a correlation between the extractants and the concentrations of elements in the diagnostic leaves nor in the tissues of the whole maize plant (Zea mays L.). © 2013 Springer Science+Business Media Dordrecht.

Impacts of agricultural activities in remaining forest: Campinas/SP, Brazil

Forest fragmentation occurs normally in an area around the city or with high agricultural influence, such as the Forest of Quilombo that lies in Metropolitan Campinas/SP- Brazil. This forest is one such example since it is separated from the other forest fragments in the region for several types of human action. The objective of this study is to analyze the macro and micronutrients and soil edaphic insect fauna in the forest, pasture and sugar cane and inferring the impacts caused by the Mata do Quilombo cattle farming and urban expansion in chemical aspects of soil. Samples were collected in June/11, according to the procedure of method traps pitfall traps. In addition, at each sampling point four composite samples were collected for soil fertility analysis. Samples were collected at six points: pasture, degraded forest (near pasture), preserved forest (near pasture), degraded forest (near cane sugar), preserved forest (near cane sugar), and sugar cane sugar. The samples thus prepared were analyzed Ca, P, K, Mg, pH, organic matter, H + Al, Sum of Base (SB), Base Percentage Saturation (V%), Cation Exchange Capacity (CEC) and trace elements (S, B, Cu, Fe, Mg and Zn). Generally it can be seen that the group of organisms of soil fauna presented with little biodiversity. The number of individuals also shows little species, taxonomic groups showing the highest degree of impact that the remaining forest has suffered. Regarding the analysis of fertility it can be observed that the soil of the surrounding areas of the forest is under direct influence of agriculture. © 2013 WIT Press.

Role of Ca, Fe, Cu and Zn in breast cancer: Study by X-ray fluorescence techniques and immunohistochemical analysis

In recent years, several studies have shown that concentrations of trace elements are altered in neoplastic breast tissues. However, the microenvironment and metabolic changes caused by tumors are complex and still not completely understood. Under this aspect, the combination of different techniques to investigate the role of trace elements in promoting and/or maintaining a tumor is interesting once the combination of information obtained by analytical techniques and immunohistochemical assays, associated with clinicopathological data, may allow a better metabolic understanding of trace elements in breast cancer. In this work, the role of the trace elements Ca, Fe, Cu and Zn in neoplastic breast tissues was investigated by X-ray fluorescence (XRF) techniques and immunohistochemical assays. We determined concentrations of Ca, Fe, Cu and Zn in normal and neoplastic breast tissues using energy dispersive XRF, and these values were used to set the positive or negative expression of elements in normal and neoplastic tissues. These expressions were correlated with the spatial distributions of trace elements (evaluated by micro-XRF) and with immunoexpression of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs and vascular endothelial growth factor. The results revealed that the expression of the trace elements Fe, Cu and vascular endothelial growth factor are related, indicating that higher levels of these elements can be associated with the angiogenic process in breast cancer. Also, associations between Ca, Zn and MMPs expression have been observed, possibly because of the fact that both metals are present in these proteins. © 2013 John Wiley & Sons, Ltd.

Ion beam analysis of a-C:H films on alloy steel substrate

An a-C:H thin film deposited by plasma immersion ion implantation and deposition on alloy steel (16MnCr5) was analyzed using a self-consistent ion beam analysis technique.In the self-consistent analysis, the results of each individual technique are combined in a unique model, increasing confidence and reducing simulation errors.Self-consistent analysis, then, is able to improve the regular ion beam analysis since several analyses commonly used to process ion beam data still rely on handling each spectrum independently.The sample was analyzed by particle-induced x-ray emission (for trace elements), elastic backscattering spectrometry (for carbon), forward recoil spectrometry (for hydrogen) and Rutherford backscattering spectrometry (for film morphology).The self-consistent analysis provided reliable chemical information about the film, despite its heavy substrate.As a result, we could determine precisely the H/C ratio, contaminant concentration and some morphological characteristics of the film, such as roughness and discontinuities.© 2013 Elsevier B.V.All rights reserved.

Plantas daninhas, atributos biológicos e elementos-traço em latossolo tratado com lodo de esgoto por treze anos consecutivos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estado nutricional e perfil bioquímico de zinco e selênio em pacientes com deficiência de UgA

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação dos valores séricos e hepáticos de elementos minerais em novilhas nelore, criadas extensivamente, suplementadas com mistura mineral comercial

Pós-graduação em Medicina Veterinária - FMVZ

Rochas basálticas da formação serra geral no município de Araçatuba, estado de São Paulo

Pós-graduação em Geologia Regional - IGCE

Níveis de condutividade elétrica da solução do substrato em crisântemo de vaso, em ambiente protegido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação de elementos traço em tumores de mama de cadelas e sua correlação com histopatologia e prognóstico de vida

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A influência dos elementos traços , (B, Cu, Mn, Mo e Zn) na produção de ramnolipídios por pseudomonas aeruginosa LBI

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Não-componentes da carcaça e carne de cordeiros alimentados com cana-de-açúcar associada a grãos de girassol e vitamina E

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)