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...

It was possible to quantitate the tetramethyl-p-phenylenediamine (TMPD) oxidase reaction in Azotobacter vinelandii strain O using turbidimetrically standarized resting cell suspensions. The Q(O2) value obtained for whole cell oxidation of ascorbate-TMPD appeared to reflect the full measure of the high respiratory oxidative capability usually exhibited by this genera of organisms. The Q(O2) valu...

OBJECTIVE To investigate the rate and mechanism of oxygen consumption by the vitreous. METHODS Oxygen consumption was measured with a microrespirometer. Vitreous ascorbate was measured spectrophotometrically and by gas chromatography-mass spectrometry. Vitreous degeneration was related to the rate of oxygen consumption and ascorbate concentration in samples obtained during vitrectomy. RESUL...

Oxidative stress and free radical production have been implicated in Alzheimer's disease, where low levels of the antioxidant vitamin C (ascorbate) have been shown to be associated with the disease. In this study, neuroblastoma SH-SY5Y cells were treated with hydrogen peroxide in the presence of ascorbate in order to elucidate the mechanism(s) of protection against oxidative stress afforded by ...

The ascorbate content declined rapidly in broccoli (Brassica oleracea L. var. italica) florets, but not in the stem tissue, during post-harvest senescence. Ascorbate peroxidase (APX), ascorbate oxidase (AO), l-galactono-1,4-lactone dehydrogenase (GLDH), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were investigated in gene expression a...

L-gulono-γ-lactone oxidase (Gulo) catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo) from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20) on its renal gulo mRNA expre...

Transgenic tobacco plants expressing the ascorbate oxidase (AAO) gene in sense and antisense orientations, and an Arabidopsis mutant in which the T-DNA was inserted into a putative AAO gene, were used to examine the potential roles of AAO for salt-stress tolerance in plants. AAO activities in the transgenic tobacco plants expressing the gene in sense and antisense orientations were, respectivel...