1,721,024 research outputs found
Interaction between copper and zinc in metal accumulation in rats with particular reference to the synthesis of induced-metallothionein
No full textThe effectiveness of Zn at moderating the pro-oxidant effects of Cu was evaluated in two rat models that differed in the route and mode of administration. The endpoints investigated included measurement of the concentrations of Cu, Zn, metallothionein and glutathione concentrations, as well as SOD and catalase activity, in liver, kidneys and intestine. In a sub-chronic animal model, the hepatic accumulation of Cu was achieved by administration of dietary Cu (1.8 g/kg solid diet) for 30 days after which oral Zn (6 g/kg solid diet) was given. Cu treatment induced an increase in the hepatic and intestinal concentration of Cu of 66 and 455%, respectively, that was not associated with synthesis of metallothionein synthesis, but rather appeared to be related to the higher activity of SOD. Subsequent administration with Zn after dietary Cu induced an increase in the hepatic and intestinal metallothionein content of more twice and reduced the Cu content to control values. Thus, Zn could act as both a competitor for absorption on the luminal side of the intestinal epithelium inducing the synthesis of metallothionein. In the second animal model, we studied the effects of interaction between Cu and Zn administered by i.p. injection at the dose of 3 and 10 mg/kg, respectively; Zn was administered subsequent to Cu overload. In this case, when Zn was administered, Cu was already deposited in tissues and thus there is no competition between two metals at the level of membrane transport. In this experimental model treatment with Cu alone induced liver metallothionein synthesis, and the subsequent treatment with Zn did not decrease the hepatic content of Cu. One explanation for these observations is that Zn induces the synthesis of metallothionein, which binds Cu for which it has a higher affinity. Moreover, after treatment with Zn, SOD activity in the liver decreases of almost 30% with respect to treatment with alone Cu, suggesting that Zn has a protective effect. (c) 2005 Elsevier Ireland Ltd. All rights reserved
Epistylis sp. (Ciliophora, Peritrichia) di origine antartica: morfologia e ultrastruttura
No full textInteraction model between circulatory and respiratory system
No full textThe present study was prepared in order to illustrate the gas exchange (O2 and CO2) between pulmonary blood and alveolar air. In the model, circulatory and respiratory systems have been separately simulated in order to obtain the driving functions of the interaction model. This last takes into account oxygen and carbon dioxide exchanges between alveolar air and pulmonary blood
A morphological and ultrastructural study of Epistylis sp. (Oligohymenophorea, Peritrichia) from Coulman Island, Antarctica
No full textLocalization of apoptotic cells and immunolocalization of metallothionein in zinc-treated LEC rat liver and kidney
No full textCompartmental systems. An appealing class for kinetic modeling and identification of metabolic processes.
No full textProblems which arise in quantitative studies on the kinetics of exogenous and endogenous chemical substances within the organism are examined together with approaches for their resolution. Linear and nonlinear compartmental mathematical models are presented and their relevant role for interpreting stimulus‐response experimental data is outlined. Available approaches are then discussed for the resolution of the system identification problem, including a priori and a posteriori identifiability, parameter estimation from test measurement data and optimum design of kinetic experiments. Finally, approaches to the problem of validation are reviewed
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