ATP-supported but not Site I or Site II respiratory chain-linked 45Ca2+ transport into isolated rat liver mitochondria is profoundly inhibited by a small molecule present in the cytosolic fraction. This inhibitor was purified and shown to be identical with ascorbic acid in a number of chemical properties, cytosolic abundance, susceptibility to ascorbate oxidase, and to agents that otherwise blo...

An understanding of biochemical events of cold storage may lead to more effective methods of preventing apple fruits from ripening and keeping their quality. This study aimed at determining the level of reduced and oxidized forms of ascorbic acid, and the activity of ascorbate peroxidase, catalase, and superoxide dismutase enzymes changes in pulp of Golden delicious apple cultivar during cold s...

We have recently reported a specific dose-dependent stimulation of posttranslational incorporation of tyrosine into tubulin alpha-chains of rabbit peritoneal leukocytes as induced by the synthetic peptide chemoattractant formyl-methionyl-leucyl-phenylalanine (FMLP). The present study reports a similar, specific stimulation of tubulin tyrosinolation in human polymorphonuclear leukocytes (PMN). W...

Intravenous application of high-dose ascorbate is used in complementary palliative medicine to treat cancer patients. Pharmacological doses of ascorbate in the mM range induce cytotoxicity in cancer cells mediated by reactive oxygen species (ROS), namely hydrogen peroxide and ascorbyl radicals. However, little is known about intrinsic or extrinsic factors modulating this ascorbate-mediated cyto...

Ascorbate reduces the oxidation rate of catecholamines and, by an independent mechanism, enhances rabbit aortic ring contractions initiated by catecholamines. The largest significantly different fractional increases in force produced by ascorbate enhancement of norepinephrine (NE), epinephrine, phenylpropanolamine (PPA), and ephedrine (Eph) are 5.5, 1.8, 1.6, and 1.3 times, respectively. In phy...

Inhalation of soluble chromium(VI) is firmly linked with higher risks of lung cancer in humans. However, comparative studies in rats have found a high lung tumorigenicity for moderately soluble chromates but no tumors for highly soluble chromates. These major species differences remain unexplained. We investigated the impact of extracellular reducers on responses of human and rat lung epithelia...

BACKGROUND Angiogenesis is critical to tumor growth and is therefore a potential target for cancer therapy. As many current inhibitors of angiogenesis exhibit host toxicity, natural alternatives are needed. At millimolar concentrations, ascorbate (vitamin C) inhibits migration and tubule formation by mature endothelial cells and endothelial progenitors. In the present study, we examined the eff...

Erythrocytes can reduce extracellular ascorbate free radicals by a plasma membrane redox system using intracellular ascorbate as an electron donor. In order to test whether the redox system has electrogenic properties, we studied the effect of ascorbate free radical reduction on the membrane potential of the cells using the fluorescent dye 3,3'-dipropylthiadicarbocyanine iodide. It was found th...

Werner syndrome (WS) is a rare autosomal disease characterized by the premature onset of several age-associated pathologies. The protein defective in WS patients (WRN) is a helicase/exonuclease involved in DNA repair, replication, transcription and telomere maintenance. Hypoxia-inducible factor-1 (HIF-1) is a decisive element for the transcriptional regulation of genes essential for adaptation ...