developing simple, sensitive and selective sensing systems for dopamine is important due to its biological significance. in this work, a silver nanoparticles-modified carbon paste electrode (agnps-cpe) has been constructed and used to detect of dopamine (da) in the simultaneous presence of ascorbic acid (aa) and uric acid (ua) at neutral ph 7.0 by cyclic voltammetry. the modified electrode show...

The presence of ascorbic acid in gastric juice may protect against gastric carcinoma and peptic ulceration. This study examined the effect of Helicobacter pylori (H pylori) on the secretion of ascorbic acid into gastric juice by measuring fasting plasma and gastric juice ascorbic acid concentrations in patients with and without the infection and also before and after its eradication. Gastric ju...

Ascorbic acid in soluble extracts of neural tissue can account for the increase in surface acetylcholine receptors (AChR's) seen on L5 myogenic cells treated with crude brain extract (Knaack, D., and T. R. Podleski, 1985, Proc. Natl. Acad. Sci. USA., 82:575-579). The present study further elucidates the nature of the response of L5 cells to ascorbic acid. Light autoradiography showed that ascor...

Ascorbic acid is frequently administered intravenously by alternative health practitioners and, occasionally, by mainstream physicians. Intravenous administration can greatly increase the amount of ascorbic acid that reaches the circulation, potentially increasing the risk of oxalate crystallization in the urinary space. To investigate this possibility, we developed gas chromatography mass spec...

There have been numerous reports suggesting that the metabolism of ascorbic acid in humans and in animals is affected by stress.l However, detailed information which would permit an analysis of the underlying mechanism is not available. From the variety of effects cited, it would appear that no single mechanism can explain all of the findings. It has been suggested that increased ascorbic acid ...

Chemical methods for the determination of reduced ascorbic acid (Zascorbic acid) are based upon its reducing properties. The indophenol method of Bessey (1, 2) and the perinaphthindantrione hydrate method of Moubasher (3) are examples of these methods. Modifications to increase the specificity of the indophenol method have been presented by Robinson and Stotz (4), Lowry, Lopez, and Bessey (5), ...

Ascorbic acid appears to have vasodilatory properties, but the underlying mechanisms are not well understood. The aims of this study were to define the acute effects of locally infused ascorbic acid in human veins and to explore underlying mechanisms by using pharmacological tools in vivo. Ascorbic acid was infused in dorsal hand veins submaximally preconstricted with the alpha(1)-adrenoceptor ...

The H-point standard addition method was applied to kinetic data for simultaneous determination of citric and ascorbic acid or selective determination of ascorbic acid in presence of citric acid. The method is based on the difference in the rate of reaction of citric and ascorbic acid with copper(II)-ammonia complex. The linear dynamic ranges for the two analytes of citric and ascorbic acid are...

The instability of ascorbic acid in weakly acid solutions has recently been shown to be due to the copper content of the solutions (1). By strict elimination of copper, solutions of ascorbic acid are stable below pH 7.6. The preparation of copper-free reagents, however, is not very practical and in analytical procedures would not eliminate copper contamination from the materials analyzed. The u...