Showing papers by "M. George Cherian published in 1992"
TL;DR: Both intracellular GSH and MT levels may provide protection against cytotoxicity of Cd in liver and even at low GSH levels, MT could partially protect the hepatic cells from Cd cytot toxicity.
115 citations
TL;DR: The induction of MT expression by arsenite (As3+) in rat liver in vivo constitutes an unusual mechanism of enhancement of MT gene expression and appears to be mediated by processes not specifically associated with binding of arsenite to MT in vivo.
82 citations
TL;DR: The relative tissue distribution and toxicity of cadmium (Cd) and mercury (Hg) in the liver and kidneys of rats when the metals are administered as either inorganic salts or complexed with MT were studied, suggesting that hepatic MT may be an important source of plasma MT under the authors' experimental conditions.
45 citations
TL;DR: The specificity of three populations of antibodies to the two metallothionein (MT) isoforms has been characterized using a competitive enzyme-linked immunosorbent assay (ELISA) and suggests that there are two populations of antibody which cross-react specifically with the MT isoforms.
32 citations
TL;DR: A competitive enzyme-linked immunosorbent assay (ELISA) for the measurement of metallothionein (MT) in tissues and body fluids has been developed and the predominant form of MT in tissues of control animals was found to be MT-2.
Abstract: A competitive enzyme-linked immunosorbent assay (ELISA) for the measurement of metallothionein (MT) in tissues and body fluids has been developed. The ELISA employs the IgG fraction of a rabbit antiserum to rat liver Cd-MT-2 polymer, a biotinylated secondary antibody, and peroxidase conjugated avidin. With a 1:4000 dilution of the immunoglobulins, typical standard curves (logit-log regression) provide a linear range of 0.1-100 ng for MT-2 and 10-1000 ng for MT-1. Fifty percent inhibition is accomplished with 15 ng and 250 ng for MT-2 and MT-1, respectively. Rat liver MT-1 and MT-2 containing different metals (Ag, Cu, and Zn) inhibited the antibodies as effectively as CdMT. However, the antibodies exhibited greater affinity for both Apo-MT isoforms. Previously reported discrepancies between results obtained by metal binding assays (e.g., Ag-hem binding) and radioimmunoassay for MT levels in tissues have been largely resolved. By addition of 1% Tween 20 to samples, the ELISA routinely estimated the total MT in samples of rat, mouse, and human liver and kidney at 88% of the value obtained by the silver-hem binding assay. Specific antibodies to MT-2 were purified from our antiserum by affinity purification using CH-Sepharose 4B coupled with rat liver MT-1. Estimation of MT in samples using purified MT-2 antibodies provided slightly lower values (72%) for MT in tissues as compared to the Ag-hem method. The predominant form of MT in tissues of control animals was found to be MT-2.(ABSTRACT TRUNCATED AT 250 WORDS)
26 citations
TL;DR: Metallothionein is expressed actively in cells transdifferentiated to hepatocytes by cadmium within the pancreas, a metal-binding protein that appears to be important in the biologic response to several toxic heavy metals in most tissues, including the Pancreas.
Abstract: A recent study from our laboratory has shown that cadmium, a toxic heavy metal, is one of the most effective agents known for inducing hepatocytic transdifferentiation of the rat pancreas. With repeated injections of cadmium, the incidence of rats with pancreatic hepatocytic foci can be as high as 93%. Cadmium is also well known as a very potent inducer of metallothionein, a metal-binding protein that appears to be important in the biologic response to several toxic heavy metals in most tissues, including the pancreas. Therefore, the present study sought to determine if metallothionein was associated with cadmium-induced transdifferentiation of pancreatic cells. Expression of metallothionein was studied immunohistochemically by the peroxidase-antiperoxidase method in tissue sections of the pancreas of rats with pancreatic hepatocytes. High levels of metallothionein were localized primarily within the pancreatic hepatocytes. Surrounding normal pancreatic islet and acinar cells were not immunoreactive. Thus...
21 citations