Overexpression of human metallothionein-III prevents hydrogen peroxide-induced oxidative stress in human fibroblasts.

Metallothioneins (MT) are ubiquitous low molecular weight metal binding proteins that may act as antioxidants. In the present study, the cloned human MT-III coding region was permanently transfected into GM00637 cells in order to investigate the antioxidative effects of this brain-specific MT isoform. GM00637/MT-III cells overexpressed MT-III mRNA versus pcDNA3 plasmid-transfected control cells (GM00637).

Suppression of inducible nitric oxide synthase and tumor necrosis factor-alpha expression by 4-nonylphenol in macrophages.

4-Nonylphenol (NP) is reported to have estrogenic activity; however, its influence on cytokine production or immune system function remains unclear. In this study we investigated the effects of NP on the production of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha), and on the level of inducible nitric oxide synthase (iNOS) and TNF-alpha gene expression in mouse macrophages. NP alone did not affect NO or TNF-alpha production.

Expression of inducible nitric oxide synthase by alpha-hederin in macrophages.

alpha-Hederin, a triterpene saponin, is reported to have antitumor activities; however, the mechanism underlying its therapeutic effects is not known. In this study, we examine the effects of alpha-hederin on the release of nitric oxide (NO) and the level of inducible nitric oxide synthase (iNOS) gene expression in mouse macrophages. alpha-Hederin elicited a dose-dependent increase in NO secretion.

Induction of cytochrome P450 1A and 2B by alpha- and beta-ionone in Sprague Dawley rats.

Beta-lonone has been reported to induce the cytochrome P450 (P450) 281 in rats. In this study, the effects of beta-ionone and an isomer, alpha-ionone, on liver P450 1A and 2B expression in Sprague Dawley rats were investigated. Subcutaneous administration of alpha- and beta-ionone 72 and 48 hr prior to sacrificing the animals induced the liver microsomal P450 1A and 2B proteins.

Rac1 prevents cisplatin-induced apoptosis through down-regulation of p38 activation in NIH3T3 cells.

In this study, the role of V12-Rac1 in the cisplatin-induced apoptosis was investigated. Cisplatin-induced apoptosis is associated with cytochrome c release, which can be inhibited by V12-Rac1 expression. The analysis of mitogen-activated protein kinase activity indicated that V12-Rac1 expression led to a decrease in p38 activity after exposure to cisplatin but not c-jun N-terminal kinase and extracellular signal-regulated kinase.

Induction of inducible nitric oxide synthase expression by 18beta-glycyrrhetinic acid in macrophages.

Glycyrrhizin (GL), a triterpenoid saponin fraction of licorice, is reported to have anti-viral and anti-tumor activities and is metabolized to 18beta-glycyrrhetinic acid (GA) in the intestine by intestinal bacteria. However, the mechanism underlying its effects is poorly understood. To further elucidate the mechanism of GA, the aglycone of GL, we investigated the effects of GA on the release of nitric oxide (NO) and at the level of inducible NO synthase (iNOS) gene expression in mouse macrophages.

Protective effect of Platycodi radix on carbon tetrachloride-induced hepatotoxicity.

The protective effects of a Platycodi radix (Changkil: CK), the root of Platycodon grandiflorum A. DC (Campanulaceae) on carbon tetrachloride (CC14)-induced hepatotoxicity and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with CK prior to the administration of CC14 significantly prevented the increased serum enzymatic activities of alanine and aspartate aminotransferase in a dose-dependent manner.

Oncogenic H-Ras enhances DNA repair through the Ras/phosphatidylinositol 3-kinase/Rac1 pathway in NIH3T3 cells. Evidence for association with reactive oxygen species.

This study investigated the role of oncogenic H-Ras in DNA repair capacity in NIH3T3 cells. Expression of dominant-positive H-Ras (V12-H-Ras) enhanced the host cell reactivation of luciferase activity from UV-irradiated and cisplatin-treated plasmids and also increased the unscheduled DNA synthesis following cisplatin or UV treatment of cells. This observed enhancement of DNA repair capacity was inhibited by transient transfection with dominant-negative H-Ras (N17-H-Ras) or Rac1 (N17-Rac1) plasmids.