Disease relevance of vitamin C

• Thrombocytopenia was generally uncommon except on arm C level 2, where the median platelet count was 26,000/mm3 [1].
• Molecular characterization of monodehydroascorbate radical reductase from cucumber highly expressed in Escherichia coli [2].
• The ascorbyl radical could only be detected in brain slices during the reperfusion-phase after 30 minutes of ischemia [3].
• We previously showed that the HSV-1 immediate-early protein ICP22 is involved in this phenomenon, since induction of IIi and depletion of IIa are deficient in cells infected with 22/n199, an HSV-1 ICP22 nonsense mutant (S. A. Rice, M. C. Long, V. Lam, P. A. Schaffer, and C. A. Spencer, J. Virol. 69:5550-5559, 1995) [4].
• Three patients in each group displayed decreased antithrombin III function, and 1 patient with a lacunar infarction had a low protein C level [5].

Psychiatry related information on vitamin C

• No significant group mean difference in speech perception scores was found in comparing the clinical MAP with the streamlined MAPs based on a single interpolated T- or C-level profile created from five behavioral measures [6].
• In the present study we evaluated protein C level in the plasma of patients with liver cell damage due to chronic alcohol consumption [7].

High impact information on vitamin C

• IL-6-mediated STAT3 activation decreased cystatin C level, an endogenous inhibitor of cathepsins, and enhanced cathepsin activities [8].
• In cultured fibroblasts of the patient, NADH-dependent cytochrome c reductase, ferricyanide reductase, and semidehydroascorbate reductase activities were severely reduced [9].
• Expression of the lacZ gene was confirmed by X-Gal chromagen staining and visualization by light and transmission electron microscopy [10].
• Genotypic analysis of the second child showed a PROC mutation, but neither PROS mutation consistent with its possession of normal protein S levels and a low/borderline protein C level [11].
• Moreover, no down-regulation of protein kinase C is observed after prolonged treatment of MCF-7 cells with DiC8, while only 10% of the initial protein kinase C level remains present in cells treated with TPA for 48 h [12].

Chemical compound and disease context of vitamin C

• When expressed in Escherichia coli fused to maltose-binding protein, monodehydroascorbate reductase has enzymatic properties comparable with purified soybean and cucumber monodehydroascorbate reductase [13].
• RESULTS: Using the building data set, four covariates significantly decreased the objective function value and interindividual variability on topotecan clearance (CL) when tested individually: ideal body weight (IBW), serum creatinine, age, and cystatin C level [14].
• Multiple linear regression analysis demonstrated that significantly higher serum levels of cathepsin S in patients with either atherosclerotic stenosis (p<0.04) or diabetes (p=0.0005) persisted after adjustment for cystatin C level, renal function, smoking, and serum glucose levels (p=0.008, p=0.0005) [15].
• Data reported here indicate that the ascorbyl radical/ascorbate ratio is an appropriate in vivo indicator of oxidative stress under conditions of iron overload [16].

Biological context of vitamin C

• The N-terminal amino acid sequence of the enzyme was Asp-Val-Lys-Thr-Leu-Gln-Glu-His-Leu-Gln-Leu-Ala-Leu-Met-Val-. The enzyme was optimally active at pH 5.2, monitored at 37 degrees C. The enzyme had affinity toward L-ascorbic acid, D-ascorbic acid, L-erythroascorbic acid, and D-erythroascorbic acid [17].
• Ascorbyl radical as natural indicator of oxidative stress: quantitative regularities [18].
• Three major advances in the past 2 years have made map-based cloning in Arabidopsis fairly routine: sequencing of the Arabidopsis genome, the availability of more than 50,000 markers in the Cereon Arabidopsis Polymorphism Collection, and improvements in the methods used for detecting DNA polymorphisms [19].
• Infection of cells with herpes simplex virus type 1 (HSV-1) results in a rapid alteration of phosphorylation on the large subunit of cellular RNA polymerase II (RNAP II), most likely on its C-terminal domain (S. A. Rice, M. C. Long, V. Lam, C. A. Spencer, J. Virol. 68:988-1001, 1994) [20].
• Interestingly, individuals with the homozygous CGT genotype (n = 40) had a mean protein C level of 94%, whereas individuals with a homozygous TAA genotype (n = 28) had a mean protein C level of 116% [21].

Anatomical context of vitamin C

• Based on our new structural model, these two heme B prosthetic groups are likely to be located on both sides of the membranes in close contact with the ascorbic acid- and semidehydroascorbic acid-binding sites, respectively, to facilitate the electron transfer across the membranes [22].
• These results suggest that the DCytb present in human erythrocytes may contribute to their ability to reduce extracellular monodehydroascorbate [23].
• By contrast, agents that raise cAMP or phorbol esters lead to an inhibition of cotransport, indicating that the NGF effect is not mediated by stimulation of either cAMP-dependent protein kinase or protein kinase C. Long term NGF treatment (> 2 days) leads to neurite formation and a maintained approximately 2-fold increase in cotransport activity [24].
• The cystatin C level was assayed in cerebrospinal fluid samples from 29 patients with brain hemorrhage and 45 control patients with other neurological diseases [25].
• The enhanced DHA uptake was not due to higher endogenous ASC levels that are normally present in exponential phase because preloading of protoplasts of different ages did not affect DHA uptake [26].

Associations of vitamin C with other chemical compounds

• Regeneration of ascorbate is achieved by monodehydroascorbate reductase (EC 1.6.5.4) using NAD(P)H as an electron donor or, alternatively, by a set of two coupled reactions requiring dehydroascorbate reductase, glutathione reductase, glutathione, and NAD(P)H [13].
• It contained 1 mol of FAD/mol of enzyme which was reduced by NAD(P)H and reoxidized by monodehydroascorbate [27].
• However, semidehydroascorbic acid was not generated when granules were incubated with epinephrine instead of the substrate dopamine, with dopamine beta-monooxygenase inhibitors, without oxygen, and when intragranular ascorbic acid was depleted [28].
• The reduced susceptibility of double antisense plants to oxidative stress correlated with suppressed photosynthetic activity, the induction of metabolic genes belonging to the pentose phosphate pathway, the induction of monodehydroascorbate reductase, and the induction of IMMUTANS, a chloroplastic homologue of mitochondrial alternative oxidase [29].
• Guaiacol peroxidase, ASC peroxidase, monodehydroascorbate oxidoreductase, DHA reductase, catalase, and glutathione reductase activities showed differential activity patterns depending on the zone of the root and their apoplastic or symplastic origin [30].
• Adrenocorticotrophic hormone stimulation increases adrenal vein but not peripheral vein vitamin C concentrations [31].

Gene context of vitamin C

• Significantly elevated levels of PAI, alpha2- antiplasmin together with low protein C level in diabetic patients may result in the disturbance of haemostatic balance favoring thrombotic events [32].
• Pretreatment with superoxide dismutase and catalase attenuated the increase in ascorbyl radical and LDH level induced by the cold injury [33].
• The percent of laboratory values measured over the study period in each group that met the criteria of transferrin saturation more than 20% was greatest in the Tabron group (58%), followed by the Feosol (47%), Chromagen (33%), and Niferex (31%) groups.(ABSTRACT TRUNCATED AT 250 WORDS)[34]
• In group I, hGH treatment raised the plasma somatomedin C level and maintained it in the range 0.5-1.5 U/ml.(ABSTRACT TRUNCATED AT 250 WORDS)[35]
• In addition to monodehydroascorbate, the enzyme catalyzed the reduction of ferricyanide and 2,6-dichloroindophenol but showed little reactivity with calf liver cytochrome b5 and horse heart cytochrome c. The kinetic data suggested a ping-pong mechanism for the monodehydroascorbate reductase-catalyzed reaction [27].

Analytical, diagnostic and therapeutic context of vitamin C

• A direct demonstration of the catalytic action of monodehydroascorbate reductase by pulse radiolysis [36].
• Molecular cloning and characterization of a cDNA encoding pea monodehydroascorbate reductase [13].
• Northern blot analysis shows that the monodehydroascorbate reductase transcript is 1.6 kilobase in size and is expressed at relatively low levels in all plant tissues examined [13].
• The method uses the endogenous ascorbyl radical (AR) concentration as a marker of oxygen radicals and requires no spin-trapping agents [37].
• Role of neutrophils in radical production during ischemia and reperfusion of the rat brain: effect of neutrophil depletion on extracellular ascorbyl radical formation [37].

References