Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:031673 (collagen)
 124,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In both animals and humans, vitamin E deficiency is associated with platelet hyperaggregability. In six E-deficient children, thrombocytosis was associated with marked hyperaggregability of their platelets to ADP, epinephrine, and collagen. Platelet malonyldialdehyde (MDA) formation was used as an indicator of prostaglandin formation, and was found to be increased during the E deficiency state. Following E repletion, both platelet aggregation and platelet MDA formation returned to normal. The addition of vitamin E to platelets in vitro has been associated with inhibition of platelet release, aggregation, and MDA formation. Extending these in vitro observations further, six normal controls were given 1600 units of vitamin E orally daily for 2 weeks to elevate their plasma E levels and the E content of their platelets in vivo. Concomitant with the elevation in their plasma E levels, there was an inhibitory effect of 12--20% on platelet MDA formation following E ingestion. These studies suggest that E deficiency increases the in vivo synthesis of platelet endoperoxides and prostaglandins, and that E excess has the opposite effect, i.e., inhibition of the endoperoxide intermediates of prostaglandin synthesis.
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PMID:Vitamin E and platelet function. 39 95

We have evaluated the influence of NBT, vitamin E, and the combination of NBT and vitamin E on the fine structure and biochemistry of platelets during incubation, and the effects of these compounds on the aggregation and secretion of platelets stimulated by collagen, thrombin, epinephrine, and ADP. Results demonstrate that NBT and vitamin E, rather than injuring platelets, appear to protect them during incubation. Togheter NBT and vitamin E blockedaggregation by epinephrine, collagen, and thrombin, but permitted a small first wave stimulated by ADP. This pattern of response to aggregating agents was similar to reactions observed in platelets pretreated with aspirin and indomethacin, both potent inhibitors of platelet prostaglandin synthesis. The findings support the concept that conversion of arachidonic acid to an activated state is an important step in prostaglandin synthesis and that electron transfer or oxidation--reduction reactions are intimately involved in the development of platelet stickiness. Although vitamin E alone does not block prot to regulate formation of endoperoxides and thromboxanes.
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PMID:Vitamin E and platelets: cooperative interactions with nitroblue tetrazolium on inhibition of adhesion, aggregation and secretion. 39 98

Administration of selenium-vitamin E (Se-E) to weanling rabbits chronically treated with adriamycin (ADR) resulted in decreased incidence and severity of cardiomyopathy and decreased cumulative mortality during a 10-week experiment. However, Se-E did not protect against extracardiac lesions or against a number of clinicopathologic alterations induced by chronic ADR toxicosis. Histopathologic alterations of ADR-induced cardiomyopathy were concentrated periarterially in the free and septal walls of the left ventricle. Initial vacuolar degeneration of injured cardiac muscle cells was followed by myofibrillar lysis and eventual cell death with subsequent interstitial fibrosis. Ultrastructurally, degenerated cardiac muscle cells had 3 prominent alterations: (1) sarcoplasmic vacuolization caused by distention of elements of sarcoplasmic reticulum and T-tubules, (2) degeneration of mitochondria forming large myelin figures from disrupted membranes, and (3) lysis of myofibrils producing granular sarcoplasmic masses. Severely injured fibers were necrotic and macrophages invaded to remove cellular debris. The interstitium was distended by edema and increased amounts of collagen. Extracardiac lesions in rabbits with chronic ADR toxicosis included the usually recognized alterations involving cell-renewal systems in kidney, testis, bone marrow, skin, and alimentary tract, as well as vacuolar degeneration of skeletal muscle and focal loss of pancreatic tissue, with ensuing pancreatic fibrosis and fat necrosis. Deaths in ADR-treated rabbits usually were precipitated by terminal septic embolism. The partial protection afforded by Se-E against ADR-induced cardiomyopathy may be associated with stabilization of the membranes of injured muscle cells or with prevention of ADR-induced inhibition of coenzyme Q10-dependent mitochondrial enzymes.
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PMID:Effect of selenium-vitamin E on adriamycin-induced cardiomyopathy in rabbits. 66 98

Two esters of vitamin E, dl-a-tocopheryl nicotinate and dl-a-tocopheryl acetate were found to be more inhibitors than tocopherol itself on platelet aggregation induced by arachidonic acid and collagen. The nicotinate was 1--5 times more potent than the acetate and 2--18 times more potent than the unesterified tocopherol in inhibiting collagen induced aggregation in human citratet platelet-rich plasma.
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PMID:Inhibition of platelet aggregation by alpha-tocopherol and its nicotinate and acetate esters. 71 83

Marked platelet hyperaggregability to adenosine diphosphate, epinephrine, and collagen was demonstrated in two children with vitamin E deficiency, with complete reversal following E supplementation. No clinical thrombotic tendency was observed during the E-deficient state. The action of vitamin E in the schema of platelet arachidonate peroxidation appears to be at the step of phosphilpase A activation, or the conversion of arachidonic acid into the cyclic endoperoxides, since the peroxidation product malonaldehyde was increased during the E-deficient state with normalization following E sufficiency.
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PMID:Vitamin E deficiency and enhanced platelet function: reversal following E supplementation. 85 35

All agents capable of triggering the platelet release reaction also stimulate prostaglandin biosynthesis in these cells. Information concerning the endoperoxides, thromboxanes, and more stable metabolites generated by the action of cyclooxygenase and lipoxygenase on arachidonic acid has accumulated rapidly, but little is known about the preliminary steps in the cleavage and preparation of arachidonic acid for insertion into the enzymatic pathways of prostaglandin synthesis. Studies in this laboratory have shown that the combination of nitroblue tetrazolium (NBT) and vitamin E which prevents oxygenation of arachidonic acid to a free radical also blocks platelet prostaglandin biosynthesis. The present study has evaluated the influence of NBT, vitamin E, and the combination of NBT and vitamin E on the fine structure and biochemistry of platelets during incubation, and the effects of these compounds on the aggregation and secretion of platelets stimulated by collagen, thrombin, epinephrine, and ADP. Results of the study demonstrate that NBT and vitamin E, rather than injuring platelets, appear to protect them during incubation. Together NBT and vitamin E blocked aggregation by epinephrine, collagen, and thrombin, but permitted a small first wave stimulated by ADP. Both ADP and thrombin induced shape change, pseudopod formation, and limited degrees of internal contraction in vitamin E-NBT-treated platelets, whereas epinephrine and collagen failed to significantly alter discoid form. This pattern of response to aggregating agents was identical to reactions observed in platelets pretreated with aspirin and indomethacin, both potent inhibitors of platelet prostaglandin synthesis. In addition, NBT-vitamin E virtually blocked the first wave of aggregation which is not affected by aspirin and indomethacin. The findings support the concept that conversion of arachidonic acid to an activated state is an important step in prostaglandin synthesis and that electron transfer or oxidation-reduction reactions are intimately involved in the development of platelet stickiness.
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PMID:Effects of nitroblue tetrazolium and vitamin E on platelet ultrastructure, aggregation, and secretion. 87 76

Tocopherol has been shown to have antiplatelet effects in insulin-dependent diabetes mellitus. However, its antiplatelet effect in non-insulin-dependent diabetes mellitus (NIDDM) remains to be established. In this report, the antiplatelet effect of tocopherol was assessed in a randomized, double-blind and crossover study of 15 NIDDM subjects. Each subject received tocopherol (dl-alpha-tocopherol nicotinate, 200 mg, tid) and a placebo for two six-week treatment periods separated by a three-week period in between for wash-out. The mechanisms of the antiplatelet effect of tocopherol were also studied in vitro. A significant decrease in platelet reactivity was observed after tocopherol treatment as compared with the pretest, and the magnitude of the decrease during tocopherol treatment was significantly evident when compared with that of the placebo treatment, as assessed by collagen (5, 10 micrograms/mL)-induced platelet aggregation of whole blood. A dose-dependent reduction in both ADP-and collagen-induced platelet aggregation was observed with tocopherol from 0.1 to 3.0 mM in vitro. No corresponding changes in ATP secretion and thromboxane synthesis were observed. Tocopherol also significantly inhibited fibrinogen-induced aggregation of elastase-treated platelets at a concentration of 0.1 mM. We demonstrated that platelet aggregation of whole blood ex vivo, among 15 NIDDM subjects was suppressed in tocopherol treatment, so tocopherol may have an antiplatelet effect in NIDDM subjects. The inhibitory effect of the platelet aggregation of tocopherol may be partially accomplished through interference with fibrinogen binding towards its receptor.
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PMID:Effect of tocopherol on platelet aggregation in non-insulin-dependent diabetes mellitus: ex vivo and in vitro studies. 135 87

Previous studies have shown that alpha-tocopherol (vitamin E) pretreatment of experimental animals can protect against acute liver necrosis induced by carbon tetrachloride. In this study we investigated whether the increase of vitamin E liver content by dietary supplementation influences chronic liver damage and cirrhosis induced by carbon tetrachloride in the rat. Our data indicate that vitamin E supplementation did not interfere with the growth rate of the animals and increased about threefold the liver's content of the vitamin. Vitamin E supplementation significantly reduced oxidative liver damage, but it was not effective in protecting against development of fatty liver and did not interfere with metabolic activation of carbon tetrachloride. Moreover, vitamin E-fed animals showed incomplete but significant prevention of liver necrosis and cirrhosis induced by carbon tetrachloride. This has been shown by means of histological examination, analysis of serum parameters and biochemical evaluation of collagen content. These results show that an increased liver content of vitamin E can afford a significant degree of protection against carbon tetrachloride-induced chronic liver damage and cirrhosis.
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PMID:Vitamin E dietary supplementation protects against carbon tetrachloride-induced chronic liver damage and cirrhosis. 139 81

The mechanisms of chronic cocaine toxicity and its potentiation by ethanol were investigated. Cocaine was administered to male C57BL/6 mice (20 mg/kg by peritoneal injection twice a day) alone or in combination with ethanol-containing diets (26% of total calories) supplied with a normal (20 IU/liter) or high content (170 IU/liter) of vitamin E. Liver levels of vitamin E, reduced glutathione, ascorbic acid, and hydroxyproline were measured. Accumulation of thiobarbituric acid-reactive substances, after in vitro stimulation of lipid peroxidation by Fe3+/ADP/ascorbate system, was measured as an index of susceptibility of hepatic membranes to oxidative stress. Plasma alanine aminotransferase, lethality, liver weight, and liver/body weight ratio were determined to assess the extent of liver toxicity. Consumption of ethanol exacerbated liver toxicity induced by cocaine treatments and reduced survival, but ethanol or cocaine treatments alone caused no or only modest mortality. Ethanol potentiated cocaine-induced accumulation of collagen in the liver and depletion of ascorbic acid. Hepatotoxicity induced by the combined ethanol plus cocaine treatment was not accompanied by a decrease in intracellular vitamin E or glutathione content. There were no changes in the basic levels and in the rate of accumulation of thiobarbituric acid-reactive substances in liver homogenates under the lipid peroxidation-stimulating system in vitro. The toxic effects of ethanol and cocaine were not reduced by the ingestion of vitamin E during short-term exposure of 21 days of treatment.
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PMID:Chronic ethanol and cocaine-induced hepatotoxicity: effects of vitamin E supplementation. 144 28

Products similar to non-enzymatic glycation end products are known to arise from the interactions between proteins and lipid peroxides in vitro. In this study, we assessed the effect of vitamin E, which possibly modifies lipid peroxide, on advanced glycation end products or similar products in vivo by measuring the fluorescence and thermal rupture time of tail tendon collagen in streptozotocin-induced diabetic rats. The diabetic rats and non-diabetic rats were fed a vitamin E supplemented diet, and a control diet starting 3 days after the streptozotocin injection. After the 4-week treatment, the serum lipid peroxide levels expressed as thiobarbituric acid reactants in the diabetic rats on control diet (15.9 +/- 2.6 mumol/l[SEM]) were significantly (p less than 0.05) higher than in the non-diabetic rats (7.9 +/- 1.3 mumol/l on control diet and 3.3 +/- 0.4 mumol/l on supplemented diet), but the levels in the diabetic rats on supplemented diet (7.9 +/- 2.3 mumol/l) were reduced to the normal levels. No significant differences were found in serum glucose and glycated haemoglobin levels within the diabetic rats on control and supplemented diets. Both the fluorescence and thermal rupture time of collagen were significantly (p less than 0.05) increased in the diabetic rats on both diets compared with those in the corresponding non-diabetic rats. Although there was no significant difference in the collagen-linked fluorescence within the diabetic rats on control and supplemented diets, the thermal rupture time was significantly (p less than 0.01) shortened with supplemented diet (10.8 +/- 0.7 min on supplemented diet vs 15.0 +/- 0.7 min on control diet).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protective effect of vitamin E supplementation on increased thermal stability of collagen in diabetic rats. 145 46


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