No abstract available.
Homocystine ; Homocystinuria*

Homocystinuria is an inborn error on the pathway of the methionine metabolism. It is mainly caused by a cystathionine B-synthase deficiency in the brain or liver. Homocystinuria is biochemically characterized by: 1) an increase of the homocystine and methionine concentration in the plasma; and 2) a decrease of the cystine with an increased excretion of homocystine in the urine. The clinical manifestations of this autosomal recessive disorder include: ectopoia lentis, skeletal abnormalities, high incidence of thromboembolism and high frequency of mental retardation. We have been experiencing a case of a 10 year old female patient who has suffered from homocystinuria. She has undergone mental retardation, poor vision caused by ocular complications and Marfanoid feautures.
Brain ; Child ; Cystathionine ; Cystine ; Ectopia Lentis* ; Female ; Homocystine ; Homocystinuria* ; Humans ; Incidence ; Intellectual Disability ; Liver ; Metabolism ; Methionine ; Plasma ; Thromboembolism

We investigated the effects of dietary folate supplementation on plasma homocysteine, vitamin B12 and hepatic levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in diet-induced hyperhomocysteinemic rats. All animals were fed 0.3% homocysteine diet for 2 weeks, then they were placed either on a 0.3% homocystine or no homocystine with or without 8 mg/kg folate diet for 8 weeks. Homocystine diet induced hyperhomocysteinemia up to 3.5-fold at 10 weeks (28.0+/-4.8 micromol/l vs. 7.9+/-0.3 micromol/l). Dietary folate supplementation caused a significant decrease in plasma homocysteine levels which had been increased by a homocystine-diet. Also, dietary folate supplementation made them return to control levels at 4 wk when the diet was free of homocystine. Plasma folate levels were markedly decreased with homocystine diet with no folate supplementation. Plasma vitamin B12 did not differ between groups. Dietary homocystine increased hepatic levels of SAM in folate supplementation group at 10 weeks (p<0.05). Dietary folate supplementation increased hepatic levels of SAM/SAH ratios in homocystine group (p<0.05). In conclusion, dietary folate supplementation can effectively ameliorate the detrimental effects of hyperhomocysteinemia.mia.
Animals ; Diet ; Folic Acid* ; Homocysteine ; Homocystine* ; Hyperhomocysteinemia* ; Metabolism* ; Plasma ; Rats* ; S-Adenosylhomocysteine ; S-Adenosylmethionine* ; Vitamin B 12

Hyperhomocyst(e)inemia is an established risk factor for atherosclerosis. We performed this study to identify the correlating variables and risk factors for atherosclerosis, as measured by the atherosclerotic score (AS), and to determine the relative risk for cardiovascular disease in relation to plasma homocyst(e)ine levels in patients on chronic hemodialysis. We evaluated and measured 61 patients on chronic hemodialysis for clinical and biochemical parameters including atherosclerotic score (AS) and plasma homocyst(e)ine. We divided patients into high and low groups, first, by the mean AS, and second, by the median value of plasma total homocyst(e)ine levels. Then we compared the variables between the two groups. Out of the 61 patients, the median plasma total homocyst(e)ine level was 24.4 micromol/L (mean+/-SD, 27.7+/-17.4; range, 9.8-127.4 micromol/L), and the median AS was 5 (mean+/-SD, 6.2+/-2.8; range, 3-13) out of a possible 20 points. AS was significantly correlated with plasma total homocyst(e)ine levels (r=0.37) and age (r=0.67). Through multivariate analysis, plasma total homocyst(e)ine level and age were determined as significant risk factors for the high-AS group (p<0.05). However, plasma total homocyst(e)ine level did not correlate with age (p>0.05). Eighteen of the 61 patients, presented with cardiovascular disease until the present study, had an AS>6. Cardiovascular disease was found more often in the high-homocyst(e)ine group (>24.4 micromol/L) than in the low-homocyst(e)ine group (odds ratio, 9.3; 95% confidence interval, 2.3-37.4). Regardless of age, hyperhomocyst(e)inemia (especially homocyst(e)ine levels >24.4 micromol/L) is a risk factor that can be modified for the development of cardiovascular disease in patients on chronic hemodialysis.
Adolescence ; Adult ; Aged ; Arteriosclerosis/etiology* ; Chronic Disease ; Female ; Homocysteine/blood* ; Homocystine/blood* ; Human ; Hyperhomocysteinemia/physiopathology* ; Male ; Middle Age ; Renal Dialysis* ; Risk Factors

This study was performed to investigate effects of dietary folic acid supplementation on plasma homocysteine levels, thiobarbituric acid reactive substances (TBARS) levels and liver SAM/SAH ratio in hyperhomocysteinaemia-induced pregnant rats. Forty-two female Sprague-Dawley rats were divided three groups (C: control diet, HFD: 0.3% homocystine and 0 mg folic acid diet, HFS: 0.3 % homocystine and 8 mg/kg folic acid diet) according to homocystine and folic acid levels in the diet. They were fed experimental diets for 5 weeks prior to the mating and also during the entire period of pregnancy till gestational day 20. Dietary folic acid supplementation caused a significant decrease in plasma homocysteine levels which had been increased by a homocystine-diet, with a concomitant increase in plasma and liver folate levels. Liver TBARS levels in homocysteine-folic acid- deficient group (HFD) were higher than those in control group. Dietary folic acid supplementation increased hepatic SAM/SAH ratio in homocysteine-folic acid- supplemetantion group (HFS) when compared to the HFD (p < 0.05). These data suggest that folate depletion and elevated plasma homocysteine may promote oxidative stress in rat livers and influence the remethylation cycle of the homocysteine metabolism detrimentally. In conclusion, dietary folic acid supplementation was found to be effective for lowering plasma homocysteine levels, relieving oxidative stress, and improving the methylation status in the body.
Animals ; Diet ; Female ; Folic Acid* ; Homocysteine* ; Homocystine ; Humans ; Hyperhomocysteinemia ; Liver* ; Metabolism ; Methylation ; Oxidative Stress ; Plasma* ; Pregnancy ; Rats* ; Rats, Sprague-Dawley ; Thiobarbituric Acid Reactive Substances*

It has been suggested that the elevated plasma homocysteine may lead to retinal dysfunction. We investigated the effects of plasma levels of homocysteine and folate on the retinal glial cells' injuries. Male Sprague-Dawley rats were raised either on a control diet or on an experimental diet containing 3.0 g/kg homocystine without folic acid for 10 weeks. Plasma homocysteine concentrations were measured by a HPLC-fluorescence detection method. Plasma folate and vitamin B12 levels were analyzed by a radioimmunoassay. The response of Muller cells which are the principal glial cells of the retina was immunohistochemically examined using an antibody for vimentin, a cytoskeletal protein belonging to the family of intermediate filament. At 2 weeks, the homocystine diet induced a twofold increase in plasma homocysteine, and a concomitant increase in the expression of vimentin in the Muller cells' processes spanning from the inner to outer membranes of the retina indicating arterial degeneration. At 10 weeks, the homocystine diet induced a fourfold increase in plasma homocystine, but vimentin immunoreactivity in the retinas was similar in both groups. In conclusion, increased plasma homocysteine levels have influence on morphological and functional changes of Muller cells in the retina.
Diet ; Ependymoglial Cells ; Folic Acid ; Homocysteine ; Homocystine ; Humans ; Hyperhomocysteinemia* ; Intermediate Filaments ; Male ; Membranes ; Neuroglia* ; Plasma ; Radioimmunoassay ; Rats, Sprague-Dawley ; Retina ; Retinaldehyde* ; Vimentin* ; Vitamin B 12

OBJECTIVE: To investigate the relationship between serum level of homocysteine and the development of collaterals in patients with severe coronary artery stenosis (SCAS). METHODS: Eighty patients with at least one vessel stenosis over 90% among the 3 main vessels of coronary artery were consecutively enrolled into the study according to angiographic estimation. The development of collaterals was classified by Rentrop's method. RESULTS: The serum levels of homocysteine among the single-vessel, bi-vessel and tri-vessel coronary artery disease groups had no significant difference; there was no linear correlation between the serum level of homocysteine and Gensini's score. The level of homocysteine in the poorly developed collaterals was significantly higher than that in the well-developed collaterals in the SCAS patients (P<0.001). Multiple stepwise logistic analysis revealed that homocysteine negatively correlated with the development of collaterals (P<0.001, odds ratio=0.353; 95% confidence interval=0.201 - 0.620), whereas it positively correlated with the number of stenosis vessels. CONCLUSION The serum level of homocysteine is independently and negatively associated with the development of collateral circulation in severe SCAs patients.
Adult ; Aged ; Aged, 80 and over ; Collateral Circulation ; Coronary Angiography ; Coronary Circulation ; Coronary Stenosis ; blood ; physiopathology ; Female ; Homocystine ; blood ; Humans ; Logistic Models ; Male ; Middle Aged

Folate and vitamin B12 are essential cofactors for homocysteine (Hcy) metabolism. Homocysteinemia has been related with cardiovascular and neurodegenerative disease. We examined the effect of folate and/or vitamin B12 deficiency on biomarkers of one carbon metabolism in blood, liver and brain, and analyzed the correlation between vitamin biomarkers in mild and moderate homocysteinemia. In this study, Sprague-Dawley male rats (5 groups, n = 10) were fed folate-sufficient diet (FS), folate-deficient diet (FD) with 0 or 3 g homocystine (FSH and FDH), and folate-/vitamin B12-deficient diet with 3 g homocystine (FDHCD) for 8 weeks. The FDH diet induced mild homocysteinemia (plasma Hcy 17.41 +/- 1.94 nmol/mL) and the FDHCD diet induced moderate homocysteinemia (plasma Hcy 44.13 +/- 2.65 nmol/mL), respectively. Although liver and brain folate levels were significantly lower compared with those values of rats fed FS or FSH (p < 0.001, p < 0.01 respectively), there were no significant differences in folate levels in liver and brain among the rats fed FD, FDH and FDHCD diet. However, rats fed FDHCD showed higher plasma folate levels (126.5 +/- 9.6 nmol/L) compared with rats fed FD and FDH (21.1 +/- 1.4 nmol/L, 22.0 +/- 2.2 nmol/L)(p < 0.001), which is the feature of "ethyl-folate trap"by vitamin B12 deficiency. Plasma Hcy was correlated with hepatic folate (r = -0.641, p < 0.01) but not with plasma folate or brain folate in this experimental condition. However, as we eliminated FDHCD group during correlation test, plasma Hcy was correlated with plasma folate (r = -0.581, p < 0.01), hepatic folate (r = -0.684, p < 0.01) and brain folate (r = -0.321, p < 0.05). Hepatic S-adenosylmethionine (SAM) level was lower in rats fed FD, FDH and FDHCD than in rats fed FS and FSH (p < 0.001, p < 0.001 respectively) and hepatic S-adenosylhomocysteine (SAH) level was significantly higher in those groups. The SAH level in brain was also significantly increased in rats fed FDHCD (p < 0.05). However, brain SAM level was not affected by folate and/or vitamin B12 deficiency. This result suggests that dietary folate- and vitamin B12-deficiency may inhibit methylation in brain by increasing SAH rather than decreasing SAM level, which may be closely associated with impaired cognitive function in nutritional homocysteinemia.
Animals ; Biomarkers ; Brain ; Carbon ; Diet ; DNA Methylation ; Folic Acid ; Homocysteine ; Homocystine ; Humans ; Hyperhomocysteinemia ; Liver ; Male ; Methylation ; Neurodegenerative Diseases ; Plasma ; Rats ; S-Adenosylhomocysteine ; S-Adenosylmethionine ; Vitamin B 12 ; Vitamin B 12 Deficiency ; Vitamins

OBJECTIVEThe renal impairment in children with methylmalonic aciduria has seldom been reported. To improve knowledge in this aspect, clinical data of five cases with methylmalonic aciduria with renal involvement were analyzed and the results are reported in this paper, which may be of some help in early diagnosis, treatment and in achieving favorable prognosis.

METHODSUrine methylmalonic acid was measured by gas chromatography-mass spectrometry analysis, if the content exceeded the normal range and vitamin B12 deficiency was excluded, the diagnosis of methylmalonic aciduria was confirmed. Homocysteine in plasma was also measured with fluorescence polarization immunoassay to make sure if concomitant homocysteinemia existed. From January 2002 to January 2005, five patients who had renal impairment were diagnosed as methylmalonic aciduria by urinary organic acid analysis. Among them, three were male, two were female, aged from seven months to 26 years, with average of 13 years. Three were presented to pediatric nephrology clinic with hematuria, proteinuria or edema, the other two were presented to pediatric neurology clinic first for psychomotor retardation. Their clinical features, laboratory findings, treatment regimens and prognosis were analyzed and summarized.

RESULTSAll the five patients with methylmalonic aciduria were found to have various degrees of renal impairment, manifested as hematuria or proteinuria. Among them, two cases had gross hematuria and three had microscopic hematuria. Edema was found in two cases and hypertension occurred in one case. Early indicators of renal damage, such as microalbunminuria, N-acetyl-beta-D glucosaminidase, transferrin and alpha-microglobulin showed glomerular and tubular dysfunction. Clinically nephrotic syndrome was diagnosed in one case, the other four cases were diagnosed as glomerulonephritis, and two cases had renal failure. Renal biopsy was performed in one case, tubulo-interstitial damage and mesangial proliferation appeared. Mental retardation and psychomotor disorder were chief nervous system complaints. Leukodystrophy was the main finding on imaging. Megaloblastic anemia was found in three cases. All the five patients were cobalamin-responsive type. Renal impairment was alleviated following treatment, edema and gross hematuria as well as hypertension disappeared later, proteinuria diminished, renal function improved, central nervous system symptoms and hematopoietic function ameliorated.

CONCLUSIONIn patients with hematuria, proteinuria or renal failure of unknown origin, metabolic screening and urinary organic acid analysis should be performed as early as possible to confirm the diagnosis.

Adolescent ; Adult ; Amino Acid Metabolism, Inborn Errors ; complications ; diagnosis ; Child ; Female ; Gas Chromatography-Mass Spectrometry ; Homocystine ; blood ; Humans ; Infant ; Kidney Diseases ; etiology ; Kidney Function Tests ; Male ; Methylmalonic Acid ; urine ; Young Adult

Homocysteine is a significant but modifiable risk factor for vascular diseases, including stroke. While several pathological processes may be involved, homocysteine can cause significant endothelial impairment and compromise vascular nitric oxide (NO) bioactivity. Endothelial dysfunction can be characterized not only by impaired vasoreactivity with decreased availability of NO but also abnormal inflammatory cell-endothelial interactions and increased expression of cell adhesion molecules. Nuclear factor-kappa B (NF-kappaB) is a transcriptional factor which plays a coordinating role in inflammation and cellular proliferation and may be involved in early atherosclerosis. Experimentally, we investigated the effects of folate supplementation on endothelial nitric oxide synthase (eNOS) activity in the hyperhomocysteinemic rat brain and related the changes of eNOS activity to the expression of NF-kappaB. Animals were raised on an experimental diet containing 0.3% homocystine for 4 weeks or on a 0.3% homocystine diet for 2 weeks with or without folate supplementation (8 mg/kg diet). The cerebrovascular endothelial nitric oxide synthase (eNOS) activity was investigated by the immunohistochemical method. Cerebral contents of eNOS and NF-kappaB were also evaluated with the western blot analysis. At 4 wks, diet- induced hyperhomocysteinemia up to 4-fold (control: 6.5+/-0.4 micromol/L, homocystine: 26.2+/-2.5 micromol/L), and a reduction in the expression of cerebral eNOS with a concomitant increase in NF-kappaB. Dietary folate supplementation caused a significant decrease in plasma homocysteine levels with a concomitant increase in hyperhomocysyeinemia-induced reduction of the cerebral eNOS and decrease in hyperhomocysyeinemia-induced NF-kappaB expression.
Animals ; Atherosclerosis ; Blotting, Western ; Brain ; Cell Adhesion Molecules ; Cell Proliferation ; Diet ; Folic Acid* ; Homocysteine ; Homocystine ; Hyperhomocysteinemia* ; Inflammation ; NF-kappa B ; Nitric Oxide ; Nitric Oxide Synthase Type III* ; Pathologic Processes ; Plasma ; Rats ; Risk Factors ; Stroke ; Vascular Diseases