Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reactive vascular-injuring amino acid homocysteine was previously shown to be increased in plasma in diabetic patients with clinical signs of nephropathy. In this study, plasma homocysteine was measured in type 1 diabetic patients with normoalbuminuria (n = 22), microalbuminuria (n = 40) and proteinuria (n = 14) in order to investigate whether plasma homocysteine levels are increased already at the stage of incipient nephropathy, i.e. microalbuminuria. Furthermore, patients were characterized according to the degree of retinopathy. Plasma homocysteine in the whole population (n = 76) was related to B-Folate (r = 0.38, p < 0.01), S-Creatinine (r = 0.55, p < 0.001), S-Urea (r = 0.37, p < 0.01), U-Albumin (r = 0.46, p < 0.001), urinary N-acetyl-beta- glucosaminidase (r = 0.40, p < 0.001), systolic blood pressure (r = 0.36, p < 0.01) and diabetes duration (r = 0.44, p < 0.001). There were no differences in plasma homocysteine levels between patients with normoalbuminuria (8.0 +/- 1.7 mumol l-1; mean +/- SD) and those with microalbuminuria (9.1 +/- 3.4 mumol l-1). However, patients with clinical signs of nephropathy had higher plasma homocysteine levels (12.9 +/- 5.7 mumol l-1, p < 0.01) compared to the other two groups. There was no association between plasma homocysteine levels and different degrees of retinopathy. Thus, the present study does not show any relation between plasma homocysteine levels and early stages of diabetic nephropathy or retinopathy indicating that elevated concentrations of plasma homocysteine does not explain the increased risk for atherosclerosis observed in patients with microalbuminuria.
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PMID:Lack of association between plasma homocysteine levels and microangiopathy in type 1 diabetes mellitus. 770 67

Periconceptual use of folic acid supplements by women is effective in preventing neural tube defects in the fetus. Folic acid supplements also may prevent atherosclerosis and some malignant neoplasms. Nevertheless, safety concerns have delayed recommendations to increase folic acid consumption by the general population. Among the potential safety issues of folic acid supplementation are (1) difficulty identifying cobalamin deficiency, precipitation of neurologic complications of cobalamin deficiency, and lowering of cobalamin levels; (2) folate neurotoxicity; (3) antagonism of drugs that inhibit folate metabolism; (4) reduced zinc absorption; (5) association with malignant neoplasms; (6) hypersensitivity reactions; and (7) increased susceptibility to malaria. The data that suggest that folic acid supplements are unsafe are weak and consist predominantly of case series and reports. Nevertheless, greater difficulty diagnosing cobalamin deficiency due to "masking" of hematologic abnormalities by folic acid is a potential risk. Strict vegetarians need to be informed that they are at risk of cobalamin deficiency. Physicians need to be aware that routine hematologic indexes have a low sensitivity for cobalamin deficiency, especially in patients who are receiving folic acid supplements. Because no high-quality data exclude specific adverse effects, physicians should be vigilant in identifying detrimental effects when patients increase their consumption of folic acid.
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PMID:How safe are folic acid supplements? 869 61

Hyperhomocysteinemia, defined as an elevated concentration of homocysteine in the fasting state or after methionine loading, is an independent risk factor for premature atherosclerosis and venous thrombosis. The role of the methionine loading test (MLT) is, however, controversial. To determine the additional value of the MLT for diagnosis of hyperhomocysteinemia, we prospectively studied 281 patients with premature arterial disease and 148 of their first-degree relatives in the outpatient clinic of a general hospital. Total plasma homocysteine (fasting and 6 hours after methionine loading), folic acid, cobalamin, pyridoxine, and creatinine concentrations were measured. Hyperhomocysteinemia was defined as a fasting homocysteine concentration and/or an increase in homocysteine concentration after methionine loading exceeding the 95th percentile of a healthy control group. Hyperhomocysteinemia was found in 141 (33%) of the 429 subjects: 15% were diagnosed by fasting homocysteine concentration and 18% by MLT. Seventy-eight (55%) of the 141 hyperhomocysteinemic persons were diagnosed only by the MLT. Folic acid was lower in the group with an elevated fasting homocysteine concentration than in those with only an abnormal MLT result (11 versus 15 nmol/L, p = 0.002). Folic acid was significantly negatively correlated, and creatinine significantly positively correlated, with both fasting homocysteine concentration and increase in homocysteine concentration. Negative correlations of cobalamin and pyridoxine with fasting homocysteine concentration were found. In conclusion, the MLT is necessary for diagnosis of hyperhomocysteinemia, because a considerable number of hyperhomocysteinemic persons (55%) remain undiagnosed with the determination of a fasting homocysteine concentration alone.
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PMID:Methionine loading test is necessary for detection of hyperhomocysteinemia. 966 74

After a thorough review of the available literature, it appears that hyperhomocysteinemia is an independent risk factor for CHD. Furthermore, folic acid has been shown to reduce homocysteine concentration. Nevertheless, CHD is a multifactorial process, and many risk factors play a role in its pathogenesis. Several unanswered questions remain regarding the role of folic acid supplementation in hyperhomocysteinemia (Table 3). The absolute homocysteine concentration at which cardiovascular risk increases is not certain, and the magnitude of homocysteine-lowering needed to prevent events is unknown. Consequently, the number needed to treat cannot be calculated for folic acid supplements. Based on these data, the populations in whom to evaluate a homocysteine concentration have yet to be described. Because the POEMs are not yet available, it is unknown whether supplemental folic acid to lower homocysteine concentration will reduce CHD morbidity and mortality. It will take several years before any randomized, controlled trials are done, and primary prevention trials will need to be of very long duration to show any change in outcomes. Widespread use of folic acid supplementation has been recommended, however, and the need for clinical outcomes might be precluded. Even in the absence of outcome data, the potential benefits of using folic acid appear to outweigh any risks. A diet high in folic acid should be encouraged in everyone (Table 4). The FDA-mandated folic acid fortification of enriched grain products is most likely insufficient to lower homocysteine concentrations meaningfully, and a daily multivitamin that contains 400 microg of folic acid should be considered for patients who have documented CHD (especially when other risk factors are absent or in patients with premature atherosclerosis) and men and women who have cardiovascular risk factors, in addition to women of childbearing potential. Folic acid supplementation in the form of a multivitamin once daily is safe and inexpensive and might prevent the development and progression of CHD.
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PMID:Homocysteine and cardiovascular disease. 979 69

Fasting hyperhomocysteinemia is an independent risk factor for coronary artery disease, stroke, peripheral vascular atherosclerosis, and for arterial and venous thromboembolism. The risk for cardiovascular disease with homocysteine is similar to conventional risk factors. The interaction of hyperhomocysteinemia with hypertension and smoking is strong and the combined effect is more than multiplicative. The combined effect of homocysteine and cholesterol is additive. Homocysteine produces atherosclerosis, thromboembolism, and vascular endothelial cell injury. Vascular dysfunction produced by homocysteine may be due to endothelial cell damage. Homocysteinemia-induced atherosclerosis is probably due to various factors including endothelial cell injury, inability to sustain S-nitroso-homocysteine formation because of imbalance between production of nitric oxide by dysfunctional endothelium and homocysteine, smooth muscle cell proliferation, and thromboembolism. There is strong evidence that endothelial cell injury is associated with oxidative stress produced by homocysteine. Hyperhomocysteinemia is associated with numerous conditions, including coronary disease, stroke, peripheral vascular disease (carotid artery and cerebrovascular atherosclerosis), venous thrombosis, renal disease, diabetes mellitus, and organ transplant. Folic acid, vitamin B12 and B6 have been shown to be beneficial in reducing plasma homocysteine levels. Folic acid is specifically very effective, safe and inexpensive.
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PMID:Homocysteine, a Risk Factor for Cardiovascular Disease. 982 15

Elevated levels of plasma total hornocysteine are now accepted as an independent risk factor for premature atherosclerosis. Nutritional, environmental and genetic factors may contribute to increase the levels of homocysteine. The exact pathogenesis of vascular damage induced by homocysteine is still not completely understood. Various mechanisms have been proposed, including a significant prooxidative activity, a stimulation of smooth muscle cells proliferation and an endothelial dysfunction. Folate, pyridoxine and cyanocobalamin are important cofactors for homocysteine metabolism. In most cases, elevated homocysteine can be reduced by administration of vitamin supplements. It has not yet been demonstrated that reduction in mortality and morbidity can be achieved with these regimens. However, food supplementation with folic acid has been recommended for treatment or prevention of homocysteine-related disorders in the North American population. Appropriate clinical trials are needed to evaluate the effect of lowering moderate homocysteine levels on atherosclerosis.
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PMID:[Moderate hyperhomocysteinemia and atherothrombosis]. 992 87

An increased plasma homocysteine concentration is a risk factor for atherosclerosis. Folic acid lowers homocysteine but the optimal dose in patients with coronary artery disease (CAD) is unclear. This placebo-controlled, single-blind, dose-ranging study evaluates the effect of low-dose folic acid on homocysteine levels in 95 patients aged 61 +/- 11 years (mean +/- SD) with documented CAD. Patients in each group were given either placebo or 1 of 3 daily supplements of folic acid (400 microg, 1 mg, or 5 mg) for 3 months. Each active treatment arm also received 500 microg vitamin B12 and 12.5 mg vitamin B6. Total plasma homocysteine levels were measured after 30 and 90 days. Folic acid 400 microg reduced homocysteine levels from 13.8 +/- 8.8 to 9.6 +/- 2.0 micromol/L at 90 days (p = 0.001). On 1- and 5-mg folic acid, levels decreased from 13.0 +/- 6.4 to 9.8 +/- 4.0 micromol/L (p = 0.001) and from 14.8 +/- 6.9 to 9.7 +/- 3.3 micromol/L (p < 0.001), respectively. The decrease was similar in all treatment groups. There was no significant change with placebo. Although the sample size is small, these findings suggest that daily administration of 400 microg/day folic acid combined with vitamin B12 and vitamin B6 may be equivalent to higher doses in reducing homocysteine levels in patients with CAD.
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PMID:Reduction of homocysteine levels in coronary artery disease by low-dose folic acid combined with vitamins B6 and B12. 1019 Mar 92

Elevated plasma homocysteine levels are associated with vascular disease and thrombosis. Premature atherosclerosis and thromboembolism are seen in children who are homozygotes for defects in enzymes responsible for the metabolism of homocysteine. Adults with heterozygous defects have less marked elevations of homocysteine, and onset of atherosclerosis and vascular disease are delayed into the fourth and fifth decade of life. Homocysteine can damage vascular endothelium, cause proliferation of vascular smooth muscle, activate platelets, promote lipid peroxidation, and activate the coagulation cascade. Epidemiologic studies have linked elevations in plasma homocysteine with coronary artery disease, cerebrovascular disease, and thromboembolism. Folic acid, in combination with vitamins B6 and B12, can normalize homocysteine levels in most patients. Although randomized trials assessing the efficacy of homocysteine reduction have yet to be completed, treatment with vitamin supplementation should be considered in all patients at risk for vascular disease.
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PMID:Homocysteine: evidence for a causal relationship with cardiovascular disease. 1034 72

Blood homocyst(e)ine levels are an important, independent and frequent risk factor for clinical atherosclerosis and venous thrombosis. Folic acid, vitamins B6 and B12, renal and thyroid functions, certain medications and certain genotypes are known to modulate plasma homocyst(e)ine levels. Intake of B vitamins through diet, supplementation and fortified foods effectively reduces homocyst(e)ine concentration and thus may reduce the risk of cardiovascular disease. This is true even in individuals who are genetically predisposed to hyperhomocyst(e)inemia. Randomized clinical trials are needed to investigate these effects further.
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PMID:Homocyst(e)ine, vitamins and genetic interactions in vascular disease. 1035 Jun 83

Homocysteine is associated with atherosclerosis and enhanced cardiovascular risk. In previous studies, treatment with folic acid up to 15 mg/d failed to correct hyperhomocysteinemia in the majority of end-stage renal disease patients. A dose of 30 or 60 mg of folic acid per day was compared with 15 mg/d in an attempt to normalize hyperhomocysteinemia in 150 hemodialysis patients. In a randomized, double-blind, multicenter study, 144 patients completed the 4-wk treatment period and 121 patients completed the 6-mo follow-up. Total homocysteine plasma levels were reduced by 32.1% (15 mg/d), 29. 9% (30 mg/d), or 37.8% (60 mg/d) with no significant differences found between the three treatment groups. Baseline total homocysteine plasma concentration was an independent predictor of the response to folic acid therapy (P = 0.0001), whereas the 5, 10-methylenetetrahydrofolate reductase polymorphisms (MTHFR 677C --> T and 1298A --> C) had no influence. Nevertheless, patients with the MTHFR 677TT genotype more frequently attained normal total homocysteine plasma levels than patients with the CC or CT genotype (P = 0.025). In response to 60 mg of folic acid per day, TT genotype patients had lower folate plasma levels compared to CC or CT genotype patients (P = 0.016). After completion of the 4-wk treatment period with 30 or 60 mg of folic acid per day, there was a marked rebound of total homocysteine plasma levels at the end of the follow-up in patients with the MTHFR 677TT genotype, which even exceeded baseline values in several patients (P = 0.0001). This study clearly demonstrates that doses of 30 or 60 mg of folic acid per day are not more effective than 15 mg/d in reducing hyperhomocysteinemia in regular hemodialysis patients. Patients with the MTHFR 677TT genotype are more likely to realize normal total homocysteine plasma levels. Folic acid at 30 or 60 mg/d but not 15 mg/d results in a rebound of total homocysteine plasma concentrations when treatment is stopped.
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PMID:Effect of high dose folic acid therapy on hyperhomocysteinemia in hemodialysis patients: results of the Vienna multicenter study. 1082 Jan 75


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