The effect of ascorbic acid on blood histamine level and delayed-type hypersensitivity was studied in thirty male guinea pigs. Animals were sensitized to B.C.G., trichophytin and mallein during the first four weeks. The diet was ad libitum during this period. After this "sensitization period" animals w er e tested intradermally with tuberculin, trichophytin and mallein. The number and diam...

We have examined the effects of ascorbate upon amino acid uptake by the in vitro toad cornea. Physiologic levels of ascorbate increase the uptake of leucine by approximately 35% but have no effect upon the uptake of alanine. Uncouplers of oxidative phosphorylation do not inhibit the stimulation by ascorbic acid of leucine accumulation, indicating the increased synthesis of ATP is not the mechan...

Information on dimethyl nitrosamine (DMN)-induced toxicity on endocrine functions is still scanty. This study therefore investigated the outcomes of DMN-induced toxicity on endocrine (thyroid and reproductive) functions, as well as kallikrein-3 level, and effects of ascorbate treatments in male wistar rats. Thirty animals divided into six groups of five rats each were used. Group I animals were...

Incubation of human leukocytes with ascorbic acid at neutral pH and at concentrations 10-50 times that of normal blood levels augmented both the in vitro random migration and chemotaxis of the cells by 100-300% without influencing their phagocytic capacity. Enhancement of mobility by ascorbate was evident for isolated neutrophils, eosinophils, and mono-nuclear leukocytes and was independent of ...

Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR). Pharmacological ascorbate has been shown to have tumor-specific toxic effects d...

The glutathione-ascorbate redox pathway in chloroplasts is a complex network of spontaneous, photochemical, and enzymatic reactions for detoxifying hydrogen peroxide. This article presents a comprehensive sensitivity analysis of the system. A model has been constructed to simulate oxidative stress conditions, enabling steady-state concentrations of the metabolites involved in the pathway and ph...

l-Ascorbate, commonly known as vitamin C, serves as an antioxidant and cofactor essential for many biological processes. Distinct ascorbate biosynthetic pathways have been established for animals and plants, but little is known about the presence or synthesis of this molecule in invertebrate species. We have investigated ascorbate metabolism in the nematode Caenorhabditis elegans, where this mo...

The promoting effect of sodium L-ascorbate on two-stage urinary bladder carcinogenesis in F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine at levels of 0.01 and 0.05% in drinking water was studied. Administration of 5.0% but not of 1.0% sodium L-ascorbate in the diet significantly increased the incidence and number of preneoplastic lesions, papillary or nodular hyperplasia, papill...

Ascorbate (vitamin C) is essential for cell metabolism, and its supply to the human diet derives basically from the consumption of fruits and vegetables. Several biosynthetic pathways of ascorbate have been reported in plants, the major physiological one being the so-called Smirnoff-Wheeler pathway. Ascorbate is a powerful antioxidant in plants, although it also plays an important role in hormo...

Pharmacological doses (> 1mM) of ascorbate (a.k.a., vitamin C) have been shown to selectively kill cancer cells through a mechanism that is dependent on the generation of H2O2 at doses that are safely achievable in humans using intravenous administration. The process by which ascorbate oxidizes to form H2O2 is thought to be mediated catalytically by redox active metal ions such as iron (Fe). Be...