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Query: UMLS:C0003969 (vitamin C deficiency)
 625 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Manual presentation of a liquid scorbutogenic diet permitted a more complete characterisation of the terminal stages of scurvy in guinea pigs. A bioflavonoid preparation from orange peel, previously shown both to increase the tissue concentrations of ascorbic acid and to stimulate the growth of hypovitaminotic C guinea pigs, had no influence on the survival time of scorbutic guinea pigs. Tetrahydrofolic acid, reported to possess 40% of the activity of ascorbic acid in the protocollagen proline-hydroxylase system, also failed significantly to prolong the survival period. This latter finding could indicate that ascorbic acid has essential biochemical functions in addition to its involvement in the hydroxylation of proline and lysine.
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PMID:Food intake, dietary supplements and survival time of scorbutic guinea pigs. 95 49

The effects of ascorbate deficiency on carnitine biosynthesis was investigated in young male guinea pigs. Liver and kidney carnitine levels were not affected by the deficiency, but scorbutic animals had 50% less carnitine in heart and skeletal muscle than control animals. Labeled carnitine precursors, 6-N-tri-methyl-L-lysine and 4-N-trimethylaminobutyrate, both of which require ascorbate for their enzymatic hydroxylation, were injected into the vena cava of control, pair-fed and scorbutic animals. The distribution of isotope in compounds present in the liver and kidney after 1 h was determined. The uptake of trimethyllysine by the liver was less than 2% in 1 h, while the kidney took up approx. 20% of the 14C. Control and pair-fed animals converted trimethyllysine to kidney trimethylaminobutyrate 8--10 times as well as did scorbutic animals. Trimethylaminobutyrate hydroxylase, present in the liver but almost absent from the kidney, converted nearly all of substrate taken up by the liver to carnitine in both the scorbutic and control animals.
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PMID:Effect of ascorbic acid deficiency on the in vivo synthesis of carnitine. 678 20

A study was made of the effect of ascorbic acid deficiency and low levels of lysine, methionine and threonine on the cancerogenic effect of nitrosopiperidine which was fed to guinea-pigs with drinking water in a single dose of 4.25 mg/kg bw. Deficiency of the nutrients given alone or especially in combination speeded up the growth tumors induced by the cancerogenic agent. A possibility of inducing esophageal tumors in guinea-pigs has been demonstrated for the first time.
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PMID:[Effect of amino acid imbalance and ascorbic acid deficit on the carcinogenic effect of N-nitrosopiperidine]. 724 95

The effect of vitamin C deficiency on the digestive and absorptive functions of the gut has been investigated in guinea pigs. The absorption of D-glucose was significantly elevated, but that of L-leucine, L-alanine and L-lysine considerably depressed in the intestine of scorbutic guinea pigs compared to controls. The intestinal transport of vitamin B12 was also diminished. Activities of sucrase and alkaline phosphatase on the brush border were enhanced, but that of leucine aminopeptidase markedly reduced in scorbutic animals compared to controls. Maltase activity was unaffected in vitamin C deficient animals. Chemical analysis of the brush borders isolated from scorbutic animals revealed a considerable decrease in membrane protein, total lipids, phospholipids, and free cholesterol contents compared to control animals. In vivo 2-(14)C-acetate incorporation into membrane lipids suggested that the observed decrease in lipid components of the scorbutic membranes is due to reduced synthesis. Administration of ascorbic acid to scorbutic animals ameliorated the intestinal aberrations observed in scurvy.
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PMID:Effect of vitamin C deficiency in guinea pigs on intestinal functions and chemical composition of brush border membrane. 730 86

Experimental vitamin C deficiency is associated with carnitine concentrations in blood and some tissues, but is not due to a decreased ability of scorbutic animals to synthesize carnitine. The effect of experimental vitamin C deficiency on urinary carnitine excretion in vivo and carnitine transport into renal cortical brush-border membrane vesicles in vitro was investigated in guinea pigs fed normal and vitamin C-deficient diets for 24 days. Excretion of free and total carnitine was approximately fourfold greater in scorbutic animals as compared with normal guinea pigs during the last 6 days of the experimental regimen. The rate of carnitine transport into renal cortical brush-border membrane vesicles prepared from scorbutic animals was approximately 36% lower than the corresponding rate for vesicles prepared from normal animals. However, this effect was not specific, since rates of sodium gradient-dependent transport of glucose, lysine, and taurine (but not alanine) were also lower in vesicles prepared from scorbutic animals, although the magnitude of the decrease was less than for carnitine. The results are consistent with the hypothesis that carnitine depletion in vitamin C deficiency is due to decreased efficiency of carnitine reabsorption.
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PMID:Renal handling of carnitine in experimental vitamin C deficiency. 878 36

As long as cribra orbitalia manifests itself as an isolated skeletal lesion in excavated human skeletons, it is mostly diagnosed as being of nutritional origin, especially iron deficiency anemia. Since both iron and vitamin C function as cofactors at the hydroxylation of the amino acids proline and lysine in collagen, both amino acid analyses of bone collagen and the determination of bone mineral iron content was carried out at ten medieval skeletons with cribra orbitalia, opposed to ten morphologically healthy individuals from the same skeletal series. The skeletons with cribra orbitalia were significantly depleted with respect to OHpro (the OHpro/Pro-ratio being 16.9% lower than in the control group), but did not differ from the healthy individuals with respect to OHlys and iron content. No correlation was found between proline hydroxylation and age at death or degree of the disease. The data do not support the iron deficiency hypothesis. Most probably, vitamin C deficiency was responsible for the difference between diseased and morphologically healthy individuals. A combination of protein and elemental analysis of excavated bones should thus be suitable for the detection of deficient hydroxylation and its etiology: iron or vitamin C deficiency.
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PMID:[Etiology of the cribra orbitalia: effect of amino acid profile in bone collagen and the iron content of bone minerals]. 931 53

Vitamin C is an essential micronutrient. Absence from the diet will result in the deficiency disease scurvy, typically characterised by weakening of collagenous structures. High intakes of vitamin C have been associated with decreased incidence or severity of a number of diseases, including cancer and cardiovascular disease. These beneficial effects may be attributed to its antioxidant properties, although the exact mechanisms of action remain elusive. It is also unclear what intake levels are required for optimal health benefits. The task of defining optimal intakes is hindered by the lack of a reliable functional marker of tissue vitamin C status in man. Many different pathways have been investigated, but none of them have measurable outcome variables relating directly to scorbutic changes. The bone-collagen formation pathway has the potential to provide a functional index of tissue vitamin C adequacy. Vitamin C acts as a cofactor for the enzyme lysyl hydroxylase, which is required for the hydroxylation of lysine residues in procollagen chains. Pyridinoline is a mature collagen cross-link formed from three hydroxylysine residues, deoxypyridinoline is formed from two hydroxylysine and one lysine residue. Guinea-pig studies have shown an alteration in the pyridinium cross-link ratios in response to graded vitamin C intakes (Tsuchiya & Bates, 1998). In order to investigate whether these changes can be seen in a human population group, a study was carried out in rural Gambia, where there is a marked seasonal variation in dietary vitamin C. The present review discusses the rationale behind the study and presents some preliminary results.
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PMID:Vitamin C and bone markers: investigations in a Gambian population. 1450 91

Vitamin C or ascorbic acid is a hydrosoluble vitamin derived from glucose metabolism. It acts as a reductor agent required for synthesis of collagen fibers through hydroxylation of proline and lysine. It also protects the body against damage caused by the free radicals. Humans cannot synthesize ascorbic acid as they lack an enzyme called gulonolactone oxidase. Concentrations in plasma and leukocytes reflect the levels of the diet and body deposits respectively of this vitamin. Among foods with high vitamin C levels are tomatoes, potatoes, and citrus fruits such as limes, oranges and lemons. The current recommendation of daily intake of vitamin C is 90 mg/d for men and 75 mg/d for women. Patients with chronic diseases such as cancer or diabetes or those who smoke need higher doses in their usual diet. Ascorbic acid deficiency gives rise to the appearance of scurvy. This disease is rarely seen in developed countries. The symptoms develop with plasma levels below 0.15 mg/dL. Scurvy is characterized by the presence of weakness, joint pain or skin lesions in form of petechias, gum bleeding, ease of developing bruises or delay in wound healing. The most characteristic skin manifestations are purpuric perifollicular hyperkeratotic papules and the presence of kinky hair.
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PMID:[Vitamin C]. 1717 58