Chromium(VI) is a known human carcinogen which requires intracellular reduction for activation. Ascorbate (vitamin C) has been reported to function as a major reductant of Cr(VI) in animals and cell culture systems. The reaction of Cr(VI) with varying concentrations of ascorbate was studied under physiological conditions in vitro in order to determine the types of reactive intermediates produce...

Scorbutic guinea pig neutrophils (PMN) were found to produce H2O2 and kill Staphylococcus aureus as well as control PMN, suggesting that ascorbate does not contribute significantly to phagocyte H2O2 production or bacterial killing. Total and reduced ascorbate contents of human PMN was observed to fall upon phagocytosis, whereas dehydroascorbate increased to a lesser extent. These observations a...

Hypoxia-inducible factor-1 (HIF-1) is a heterodimer transcription factor whose elevated activity in many cancers helps them to survive under hypoxic conditions and enhances their capacity to grow invasively, establish metastases, and survive chemo- or radiotherapy. Optimal intracellular levels of ascorbate suppress the level and transcriptional activity of HIF-1under normoxic or mildly hypoxic ...

Degradation of the extracellular matrix (ECM) plays a critical role in the formation of tumors and metastasis and has been found to correlate with the aggressiveness of tumor growth and invasiveness of cancer. Ascorbic acid, which is known to be essential for the structural integrity of the intercellular matrix, is not produced by humans and must ...

Chondrocytes isolated from bovine articular cartilage were plated at high density and grown in the presence or absence of ascorbate. Collagen and proteoglycans, the major matrix macromolecules synthesized by these cells, were isolated at times during the course of the culture period and characterized. In both control and ascorbate-treated cultures, type II collagen and cartilage proteoglycans a...

Sepsis causes brain dysfunction. Because neurotransmission requires high ascorbate and low dehydroascorbic acid (DHAA) concentrations in brain extracellular fluid, the effect of septic insult on ascorbate recycling (i.e., uptake and reduction of DHAA) and export was investigated in primary rat and mouse astrocytes. DHAA raised intracellular ascorbate to physiological levels but extracellular as...

The ascorbate content of plants is usually increased in high light (HL), implying a function for ascorbate in the acclimation of plants to HL. Nevertheless, the importance of ascorbate in HL acclimation has not yet been tested directly. Here, we report on the acclimation process of an ascorbate-deficient Arabidopsis mutant to HL. The mutant vtc2 has only 10% to 30% of wild-type levels of ascorb...

Ascorbic acid deficiency causes qualitative and quantitative differences in the guinea pig hepatic flavin-containing monooxygenase (FMO). Kinetic studies with purified FMO indicated no significant change in the apparent Km of dimethylaniline or NADPH in ascorbate-supplemented or -deficient animals. Following purification of ascorbate-deficient guinea pig FMO by DEAE-cellulose and blue agarose c...

Plasma membranes isolated from wild-type Saccharomyces cerevisiae crude membrane fractions catalyzed NADH oxidation using a variety of electron acceptors, such as ferricyanide, cytochrome c, and ascorbate free radical. Plasma membranes from the deletion mutant strain coq3delta, defective in coenzyme Q (ubiquinone) biosynthesis, were completely devoid of coenzyme Q6 and contained greatly diminis...

Until now therapeutic concepts for human cardiovascular disease (CVD) were targeting individual pathomechanisms or specific risk factors. On the basis of genetic, metabolic, evolutionary, and clinical evidence we present here a unified pathogenetic and therapeutic approach. Ascorbate deficiency is the precondition and common denominator of human CVD. Ascorbate deficiency is the result of the in...