Plasma Total Homocysteine Concentrations Research Articles

The Role of B-Vitamins in Bone Health and Disease in Older Adults

The risk of osteoporosis and bone fractures increases with age. Several other factors are also related to bone disease including gender, race/ethnicity, physical activity, alcohol, smoking, estrogen, and calcium and vitamin D. B-vitamins (folate, B12, and B6) are also emerging dietary factors related to bone health, both individually and through their action on influencing total plasma homocysteine concentrations (tHcy). The primary objective of this review is to summarize the available data on B-vitamins and bone health, highlighting clinical trials and observational data. In populations without folic acid fortification, the totality of evidence suggests that elevated tHcy has a small but significant association with bone fracture risk and bone quality but not on bone mineral density (BMD) or bone turnover biomarkers. Very little supportive evidence exists for a direct role of folate for either BMD or fracture risk; however, the data available are quite limited. Meta-analyses and some cross-sectional and cohort studies suggest a small but significant role of vitamin B12 status on risk of fracture but not on BMD. The mechanism by which tHcy and B12 may influence bone health is not well characterized but may be through modulation of collagen cross-linking or through altering osteoclasts or osteoblasts. Much more data are needed-particularly the role that each vitamin directly has on bone, or whether the vitamins only exert their effect though tHcy concentrations. Nevertheless, consistent findings across different populations with different study designs suggest a role for tHcy and B12 in reducing fracture risk.

Effect of genetic polymorphisms involved in folate metabolism on the concentration of serum folate and plasma total homocysteine (p-tHcy) in healthy subjects after short-term folic acid supplementation: a randomized, double blind, crossover study.

Data on the effect of combined genetic polymorphisms, involved in folate metabolism, on the concentration of serum folate after folic acid supplementation are scarce. Therefore, we investigated the impact of seven gene polymorphisms on the concentration of serum folate and p-tHcy in healthy subjects after short-term folic acid supplementation. In a randomized, double blind, crossover study, apparently healthy subjects were given either 0.8mg folic acid per day (n=46) or placebo (n=45) for 14days. The washout period was 14days. Fasting blood samples were collected on day 1, 15, 30 and 45. Data on subjects on folic acid supplementation (n=91) and on placebo (n=45) were used for the statistical analysis. The concentration of serum folate increased higher in subjects with higher age (53.5±7.0years) than in subjects with lower age (24.3±3.2years) after folic acid supplementation (p=0.006). The baseline concentration of serum folate in subjects with polymorphism combination, reduced folate carrier protein, RFC1-80 GA and methylenetetrahydrofolate reductase, MTHFR677 CT+TT, was lower than RFC1-80 AA and MTHFR677 CT+TT (p=0.002). After folic acid supplementation, a higher increase in the concentration of serum folate was detected in subjects with polymorphism combination RFC1-80 GA and MTHFR677 CC than RFC1-80 GG and MTHFR CT+TT combination (p<0.0001). The baseline concentration of plasma total homocysteine (p-tHcy) was altered by combined polymorphisms in genes associated with folate metabolism. After folic acid supplementation, in subjects with combined polymorphisms in methylenetetrahydrofolate dehydrogenase, MTHFD1-1958 and MTHFR-677 genes, the concentration of p-tHcy was changed (p=0.002). The combination of RFC1-80 and MTHFR-677 polymorphisms had a profound affect on the concentration of serum folate in healthy subjects before and after folic acid supplementation.

Beneficial antioxidant properties of betaine against oxidative stress mediated by levodopa/benserazide in the brain of rats.

The present study was designed to evaluate antioxidant effects of betaine in the brain following administration of levodopa and benserazide, which are routinely used in the treatment of Parkinson's disease. Sprague-Dawley male rats were divided into levodopa (LD), Betaine (Bet.), levodopa plus betaine (LD/Bet.), levodopa plus benserazide (LD/Ben.), levodopa plus betaine-benserazide (LD/Bet.-Ben.) and control groups. The experimental groups received LD 300mg/kg, Bet. 1.5% w/w of the total diet, Ben. 75mg/kg and distilled water to controls for 10 consecutive days, orally. The concentration of plasma total homocysteine significantly increased in LD/Ben.-treated rats when compared to the other groups. Brain glutathione peroxidase (GPx) activity and glutathione content both elevated with betaine treatment in LD/Bet. and LD/Bet.-Ben groups. Superoxide dismutase activity was also higher in controls and betaine-treated rats in comparison with LD and LD/Ben. groups. Likewise, catalase activity significantly increased in control and betaine groups when compared to LD- and LD/Ben.-treated rats. In contrast, brain lipid peroxidation significantly increased in response to LD and LD/Ben. Regarding metabolism of LD in peripheral tissues, serumic dopamine concentration significantly increased in LD-treated rats in comparison with LD/Ben. group. The present results show beneficial antioxidant and methyl donor properties of betaine versus oxidative stress and hyperhomocysteinemia induced by levodopa and benserazide in an animal model.

Betaine (N,N,N-trimethylglycine) averts photochemically-induced thrombosis in pial microvessels invivo and platelet aggregation invitro.

Betaine (N,N,N-trimethylglycine) is an important food component with established health benefits through its homocysteine-lowering effects, and is used to lower total homocysteine concentration in plasma of patients with homocystinuria. It is well established that hyperhomocysteinemia is an established risk factor for cardiovascular disease and stroke. However, the possible protective effect of betaine on coagulation events invivo and invitro has thus far not been studied. Betaine was given to mice at oral doses of either 10 mg/kg (n = 6) or 40 mg/kg (n = 6) for seven consecutive days, and control mice (n = 6) received water only. The thrombotic occlusion time in photochemically induced thrombosis in pial arterioles was significantly delayed in mice pretreated with betaine at doses of 10 mg/kg (P < 0.001) and 40 mg/kg (P < 0.01). Similar effects were observed in pial venules with 10 mg/kg (P < 0.05) and 40 mg/kg (P < 0.05) betaine. Invitro, in whole blood samples collected from untreated mice (n = 3-5), betaine (0.01-1 mg/mL) significantly reversed platelet aggregation induced by adenosine diphosphate (5 µM). The number of circulating platelets and plasma concentration of fibrinogen invivo were not significantly affected by betaine pretreament compared with the control group. Lipid peroxidation (LPO) in mice pretreated with betaine was significantly reduced compared with the control group. Moreover, betaine (0.01-1 mg/mL) caused a dose-dependent and significant prolongation of PT (n = 5) and aPTT (n = 4-6). In conclusion, our data show that betaine protected against coagulation events invivo and invitro and decreased LPO in plasma.

Prevalence of hyperhomocysteinaemia and some of its major determinants in Shaanxi Province, China: a cross-sectional study.

The aim of the present study was to investigate the prevalence of hyperhomocysteinaemia (HHCY; total plasma homocysteine (tHcy) concentration >15μmol/l) and its major determinants in healthy Chinese northerners. A descriptive and cross-sectional study was conducted in Shaanxi Province, China. The study sample included 2645 participants (1042 men and 1603 women) aged >20 years. Demographic characteristics and lifestyle factors were assessed via questionnaire interviews and physical examination. Plasma levels of homocysteine and folate and methylenetetrahydrofolate reductase (MTHFR) gene polymorphism were determined according to standard methods. The prevalence of HHCY was 67·7% (81·4% in men and 58·8% in women). The geometric mean of tHcy concentration was 19·1μmol/l. The OR of HHCY were 0·44 (95% CI 0·34, 0·57) for women v. men; 1·95 (95% CI 1·41, 2·70), 1·41 (95% CI 1·05, 1·88) and 0·76 (95% CI 0·64, 0·89) for participants with smoking and alcohol drinking cessation and improved physical activity levels, respectively; 0·25 (95% CI 0·17, 0·38), 0·33 (95% CI 0·22, 0·49) and 0·56 (95% CI 0·36, 0·88) for participants with an education level of elementary school, secondary school and university v. illiterate, respectively; 1·41 (95% CI 1·13, 1·75) and 3·05 (95% CI 2·35, 3·97) for participants with CT and TT v. CC genotype at MTHFR 677C→T polymorphism, respectively. These results demonstrate that the prevalence of HHCY is considerably high in Chinese northerners, especially in TT subjects, suggesting that implementation of tHcy-lowering strategies, such as lifestyle changes, is necessary.

Meta-analysis reveals protective effects of vitamin B on stroke patients.

Stroke is the loss of brain function due to a disturbance in the blood supply to the brain resulting from either ischemia or hemorrhage. Previous studies have evaluated the clinical importance of nutritional interventions such as vitamin B supplementation in the management of acute strokes. However, it is still inconclusive whether or not vitamin B supplementation will benefit patients with acute strokes. Therefore, a meta-analysis was performed to assess the efficacy of vitamin B supplementation in the treatment of stroke patients. Medline, Embase, Scopus, and Cochrane Library databases were searched (from 1960 to June 2015) and forest plots were generated to illustrate the treatment effects. A systemic review of the electronic databases yielded 12 eligible studies consisting of 7474 patients. Forest plots from the meta-analyses of the included studies illustrated that vitamin B supplementation significantly lowered the plasma concentration of total homocysteine (SMD = −0.82; 95% CI: −0.77; Z = −29.06, p < 0.0001) and resulted in significant reduction in stroke recurrence (OR = 0.86%; 95% CI: 0.76, 0.97; Z = −2.41; p = 0.016) as well as a combined incidence of vascular events, including recurrent strokes, myocardial infarctions and vascular deaths (OR = 0.87%; 95% CI: 0.79, 0.96; Z= −2.73; p = 0.0063).Additionally, the nearly-symmetrical funnel plot (Egger’s test, t = −1.705, p = 0.1224) indicated the absence of publication bias regarding the meta-analysis that examined the effect of vitamin B supplementation on the plasma levels of homocysteine in acute stroke patients. These findings suggested that vitamin B supplementation presents a potential addition to the armamentarium for the management of acute stroke patients.

Genetic and non-genetic factors that increase the risk of non-syndromic cleft lip and/or palate development.

We investigated the relationship between non-syndromic cleft lip/palate (NSCLP) and polymorphisms in methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), methionine synthase reductase (MTRR), and RFC1, as well as the corresponding interactions with environmental factors. One hundred and forty NSCLP patients and their mothers, as well as 175 control individuals and their mothers, were recruited. Information regarding smoking and alcohol consumption was recorded. Blood samples were obtained in order to measure serum folate and cobalamin, as well as, plasma total homocysteine concentrations and to extract DNA. Polymorphisms in MTHFR(677C>T and 1298A>C), MTR(2756A>G), MTR(66A>G), and RFC1(80A>G) were analyzed by PCR-restriction fragment length polymorphism. Among the patients, 59.5% had cleft lip and palate, 22.0% had cleft palate, and 18.5% had cleft lip only. Maternal alcohol consumption and reduced folic acid concentrations in both children and mothers (P<0.001 and P=0.003, respectively) were risk factors for NSCLP. Patients and their mothers carrying the MTHFR 667T allele showed lower serum folate than CC (P=0.011 and P=0.030, respectively). Mothers who carried the MTHFR 1298C allele exhibited increased risk of having a child with NSCLP, after adjusting for alcohol consumption (OR: 1.75, 95% CI: 1.03-2.99, P=0.038). Reduced folic acid levels, alcohol consumption, and the MTHFR 677T and 1298C alleles may have contributed to NSCLP development in this sample population from Rio Grande do Norte.

Effects of polymorphisms in endothelial nitric oxide synthase and folate metabolizing genes on the concentration of serum nitrate, folate, and plasma total homocysteine after folic acid supplementation: A double-blind crossover study

ObjectivesA number of studies have explored the effects of dietary nitrate on human health. Nitrate in the blood can be recycled to nitric oxide, which is an essential mediator involved in many important biochemical mechanisms. Nitric oxide is also formed in the body from l-arginine by nitric oxide synthase. The aim of this study was to investigate whether genetic polymorphisms in endothelial nitric oxide synthase (eNOS) and genes involved in folate metabolism affect the concentration of serum nitrate, serum folate, and plasma total homocysteine in healthy individuals after folic acid supplementation. MethodsIn a randomized double-blind, crossover study, participants were given either folic acid 800 μg/d (n = 52) or placebo (n = 51) for 2 wk. Wash-out period was 2 wk. Fasting blood samples were collected, DNA was extracted by salting-out method and the polymorphisms in eNOS synthase and folate genes were genotyped by polymerase chain reaction methods. Measurement of serum nitrate and plasma total homocysteine (p-tHcy) concentration was done by high-performance liquid chromatography. ResultsThe concentration of serum nitrate did not change in individuals after folic acid supplements (trial 1); however, the concentration of serum nitrate increased in the same individuals after placebo (P = 0.01) (trial 2). The individuals with three polymorphisms in eNOS gene had increased concentration of serum folate and decreased concentration of p-tHcy after folic acid supplementation. Among the seven polymorphisms tested in folate metabolizing genes, serum nitrate concentration was significantly decreased only in DHFR del 19 gene variant. A significant difference in the concentration of serum nitrate was detected among individuals with MTHFR C > T677 polymorphisms. ConclusionsPolymorphisms in eNOS and folate genes affect the concentration of serum folate and p-tHcy but do not have any effect on the concentration of NO3 in healthy individuals after folic acid supplementation. 2014 Elsevier Inc. All rights reserved.

Plasma Total Homocysteine Level in Association With Folate, Pyridoxine, and Cobalamin Status Among Iranian Primary Breast Cancer Patients

Recently the elevated plasma total homocysteine (tHcy) concentration has been concerned as the secondary feature of tumoral proliferation and enhances the likelihood of thrombogenesis in cancer patients. The objective of this study was to determine the associations between folate, cobalamin, and pyridoxine with fasting plasma tHcy concentration in breast cancer (BC) patients. The intake levels of nutrients were assessed using a validated food frequency questionnaire in 141 newly diagnosed BC patients. The plasma tHcy and pyridoxal-5-phosphate were measured using high performance liquid chromatography with fluorescence detector. Plasma tHcy levels were observed to be significantly higher among BC participants with Stage III where the plasma concentrations of folate was also comparatively less (P < 0.05) than other stages. Dietary pyridoxine was even being consumed less at this stage (P < 0.05). The plasma, dietary, and residual variables of folate were inversely correlated with plasma tHcy concentration (P < 0.05). Dietary cobalamin was also associated negatively with tHcy (P < 0.05). The odds ratio of comparing the highest tertile of plasma cobalamin (>394 pmol/l) and folate (>11.4 ng/ml) vs. the lowest categories were associated with reduced odds of high tHcy occurrence with 0.20 (95% confidence interval: 0.04–0.98) and 0.14 (95% confidence interval: 0.03–0.64), respectively. In conclusion, nutrition-related methyl-group insufficiency could lead to imbalance in tHcy metabolism, as a possible cancer marker.

Betaine as a methyl donor and an antioxidant agent in levodopa-induced hyperhomocysteinemia and oxidative stress in rat's kidney

BACKGROUND: Betaine has been shown to be antioxidant and methyl donor effects in our recent studies. OBJECTIVES: In the present study, the antioxidant and methyl donor properties of betaine in levodopa/benserazide-mediated hyperhomocysteinemia and levodopa-induced oxidative stress in rat's kidney were examined. METHODS: Sprague-Dawley male rats were divided into levodopa (LD), Betaine (Bet.), levodopa plus betaine (LD/Bet.), levodopa plus benserazide (LD/Ben.), levodopa plus betaine-benserazide (LD/Bet.-Ben.), and control groups. The experimental groups received LD (3 × 100 mg/kg), Bet. (1.5% w/w of the total diet), Ben. (3 × 25 mg/kg), and distilled water was given to controls for 10 consecutive days, orally by gavage. RESULTS: Plasma total homocysteine (tHcy) concentration decreased significantly in Bet.-, LD/Bet.-, and LD/Bet.-Ben.- treated rats compared to LD/Ben. group. Thiobarbituric acid reactive substances concentration (as a lipid peroxidation marker) in renal tissue reduced statistically in betaine group in comparison with LD and LD/Ben. groups. Renal catalase activity increased significantly in LD-treated rats when compared to controls. Renal superoxide dismutase activity significantly decreased in LD-treated group when compared to LD/Ben. group. However, there was not any significant difference in renal glutathione peroxidase (GPx) activity among the groups. CONCLUSIONS: These findings indicate that LD and LD/Ben. have side effects in kidney due to induction of hyperhomocysteinemia and oxidative stress. In contrast, betaine acts as a promising antioxidant and methyl donor agent versus LD-induced complications.

Homocysteine, small-vessel disease, and atherosclerosis: an MRI study of 825 stroke patients.

We evaluated the relationship between hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and small-vessel disease (SVD) and atherosclerotic large-vessel disease (LVD) in stroke patients. A total of 825 noncardioembolic ischemic stroke patients whose plasma concentrations of total homocysteine were measured and whose MTHFR C677T polymorphism status was identified were included in this retrospective study. MRI of the brain and magnetic resonance angiography of the intracranial and extracranial cerebral arteries had been performed. SVD and LVD were assessed by the Scheltens scale (the SVD score) and by the number of atherosclerotic steno-occlusive arteries (the LVD score), respectively. The TT genotype of the MTHFR C677T polymorphism was associated with hyperhomocysteinemia (p < 0.001), but not with SVD (p = 0.182) or LVD (p = 0.988) scores. Multiple logistic regression analysis showed that hyperhomocysteinemia was associated with SVD (odds ratio [OR] 1.04; 95% confidence interval [CI] 1.01-1.07; p = 0.005) and LVD (OR 1.02; 95% CI 1.00-1.05; p = 0.041) scores. Hyperhomocysteinemia was related to the LVD score of extracranial arteries (p = 0.008), but not to the LVD score of intracranial arteries (p = 0.730). In multiple logistic regression analysis, however, hyperhomocysteinemia was not related to the LVD score of extracranial arteries (p = 0.255). Hyperhomocysteinemia was associated with SVD of the brain and LVD of cerebral arteries. The MTHFR C677T polymorphism was not related to SVD and LVD, although the TT genotype was an important determinant of hyperhomocysteinemia.

Plasma homocysteine concentrations in acute and convalescent changes of central retinal vein occlusion in a Chinese population.

Homocysteine is a potential risk factor for central retinal vein occlusion (CRVO), but this remains controversial. We measured fasting total plasma homocysteine (tHcy) concentrations immediately after CRVO and in the convalescent period to investigate this controversy. We measured fasting tHcy concentrations in 36 consecutive patients with CRVO within three days; and at 1, 3, and 6 months after CRVO; and once in 36 control subjects. The vitamin B12 and folate levels, and the presence of C677T MTHFR polymorphisms, were analyzed in all patients and controls. Median tHcy concentrations were not significantly higher than in matched control subjects in the acute phase of CRVO (9.66 [10.75 ± 4.09] vs. 9.25 [9.96 ± 4.02] μmol/L, P = 0.371) and 1 month after CRVO (P = 0.119). However, tHcy levels increased significantly in the convalescent period and were significantly higher than in control subjects at 3 CRVO (P = 0.010) and 6 (P < 0.001) months after CRVO. Furthermore, tHcy levels of the ischemic CRVO patients at 6 months after CRVO were significantly higher than in nonischemic CRVO patients (P = 0.028). However, these observations did not appear to be explained by alteration in serum folate, vitamin B12 concentrations, and the MTHFR C677T genotype. The tHcy levels are not immediately elevated after CRVO, but increase in the convalescent period. These data do not support the hypothesis that raised tHcy concentrations are independent risk factor for CRVO. Instead, it is possible that elevated tHcy levels may be caused by the disease process itself.

Immediate and long-term high levels of plasma homocysteine after extracorporeal shock wave lithotripsy in patients with renal stone disease.

Plasma homocysteine levels increase in patients with chronic renal failure. Numerous studies have demonstrated that kidney function is one of the most important determinants of plasma total homocysteine (tHcy) concentration. In this study we aimed to evaluate the relationship between tHcy levels and extracorporeal shock wave lithotripsy (ESWL) for patients with renal stones and to see if the change in homocysteine levels continued if renal dysfunction improved. The study consisted of 20 patients who underwent first-time ESWL for renal stones. Every patient gave 3 blood samples at 24 h before surgery and at 2 days and at 3 months after ESWL for measurement of plasma levels of tHcy, creatinine, vitamin B6, and vitamin B12. The 20 patients (12 male, 8 female) had a mean age of 42.8 ± 11.7 years. tHcy levels showed a statistically significant increase from 9.4 ± 1.4 to 18 ± 4.8 and 11.2 ± 2.1 at 2 days and at 3 months, respectively. Serum creatinine also showed a statistically significant increase compared to baseline at 2 days and at 3 months after ESWL. After first-time ESWL, the increase in serum levels of creatinine and tHcy due to renal injury, such as ischemia/reperfusion injury, may be severe and continue for a long period, such as 3 months. According to baseline levels, the increase in homocysteine levels as an indicator of oxidant stress was more severe than the creatinine levels after ESWL for renal stones. Our patients were first-time ESWL patients; however, in patients who undergo EWSL more than once long-term high tHcy levels should also be considered as renal.

Homocysteine is Linked to Macular Edema in Type 2 Diabetes

Aim: To explore the relationship between plasma total homocysteine concentration and diabetic macular edema in patients with type 2 diabetes.Methods: Patients with type 2 diabetes (n = 176) were enrolled in a cross-sectional hospital-based study. Diabetic macular edema status was documented by fundus photographs. Plasma total homocysteine concentration was measured using fluorescence polarization immunoassay. Normal control plasma homocysteine was established in 115 healthy subjects. Risk factors for diabetic macular edema were obtained from fasting blood samples and interviewer questionnaire.Results: Diabetic patients had increased plasma homocysteine compared with normal control. Plasma homocysteine levels were higher in subjects with diabetic macular edema than without ((11.4 ± 2.7) versus (8.5 ± 1.9) (μmol/l), p = 0.000). The association of homocysteine with diabetic macular edema was independent of major risk factors for diabetic macular edema (duration of diabetes, HbA1c, lipid) and determinants of higher homocysteine concentration (age, gender, serum folate and vitamin B12, renal status, and biguanide use) (OR: 1.63 (1.02–2.14), p = 0.018). Furthermore, per increase of 5.0 μmol/l plasma homocysteine was related to macular edema, after controlling for per unit increase of other factors (OR: 1.64 (1.04–2.16), p = 0.019).Conclusions: Plasma total homocysteine concentration is independently associated with the occurrence of macular edema in type 2 diabetes. Future prospective studies are warranted to clarify the relationship.

Homocysteine, an additional factor, is linked to osteoporosis in postmenopausal women with type 2 diabetes

We explored the relationship between plasma total homocysteine concentration and osteoporosis in postmenopausal patients with type 2 diabetes. Postmenopausal patients with type 2 diabetes (n = 258) were enrolled in a cross-sectional hospital-based study. Osteoporosis was documented by dual energy X-ray absorptiometry. Plasma total homocysteine concentration was measured using fluorescence polarization immunoassay. Risk factors for osteoporosis and determinants of homocysteine were obtained from blood samples and interviewer questionnaire. We found that plasma total homocysteine levels were higher in subjects with osteoporosis and diabetes than without [(9.5 ± 2.0) vs. (10.4 ± 2.4) μmol/l, p = 0.001]. The association of homocysteine with osteoporosis was independent of possible risk factors for osteoporosis in diabetes (e.g., duration of diabetes, HbA1c, body mass index, serum 25-hydroxyvitamin D, thiazolidinediones, and retinopathy) and determinants of homocysteine concentration (age, serum folate and vitamin B12, renal status, and biguanide use) [OR 1.40 (1.02-1.90), p = 0.036]. In addition, bone mineral density was closely correlated with homocysteine as a continuous variable after adjusting for age [r = -0.64 (-0.69 to -0.58), p = 0.002]. Furthermore, per increase of 5.0 μmol/l, plasma homocysteine was related to osteoporosis, after controlling for per unit increase of other factors [OR 1.42 (1.07-1.96), p = 0.027]. The optimal cut-off point for the plasma homocysteine level distinguishing diabetic patients with osteoporosis from without was 10.18 μmol/l. The results suggest that plasma total homocysteine concentration is independently associated with the occurrence of osteoporosis in postmenopausal patients with type 2 diabetes. Future prospective studies are warranted to clarify the relationship.

The control of hyperhomocysteinemia through thiol exchange mechanisms by mesna

In hyperhomocysteinemic patients, after reaction with homocysteine-albumin mixed disulfides (HSS-ALB), mesna (MSH) forms the mixed disulfide with Hcy (HSSM) which can be removed by renal clearance, thus reducing the plasma concentration of total homocysteine (tHcy). In order to assess the HSS-ALB dethiolation via thiol exchange reactions, the distribution of redox species of cysteine, cysteinylglycine, homocysteine and glutathione was investigated in the plasma of healthy subjects: (i) in vitro, after addition of 35 μM reduced homocysteine (HSH) to plasma for 72 h, followed by MSH addition (at the concentration range 10-600 μM) for 25 min; (ii) in vivo, after oral treatment with methionine (methionine, 200 mg/kg body weight, observation time 2-6 h). In both experiments the distribution of redox species, but not the total amount of each thiol, was modified by thiol exchange reactions of albumin and cystine, with changes thermodynamically related to the pKa values of thiols in the corresponding mixed disulfides. MSH provoked a dose-response reversal of the redox state of aged plasma, and the thiol action was confirmed by in vivo experiments. Since it was observed that the dimesna production could be detrimental for the in vivo optimization of HSSM formation, we assume that the best plasma tHcy lowering can be obtained at MSH doses producing the minimum dimesna concentration in each individual.

Hypomethylation of long interspersed nucleotide element‐1 in peripheral mononuclear cells of juvenile systemic lupus erythematosus patients in China

Methylation abnormalities in T lymphocytes have been reported to correlate with systemic lupus erythematosus (SLE). Previous studies identified hypomethylation in the promoter of several genes linked to SLE. Long interspersed nucleotide element-1 (LINE-1) constitutes 17-25% of the human genome, and LINE-1 hypomethylation has been reported in SLE. Limited information is available regarding LINE-1 methylation in juvenile SLE (JSLE). Methylation levels of LINE-1 in peripheral blood mononuclear cells (PBMCs) from 59 JSLE and 47 control samples were examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Total homocysteine (tHcy) concentrations in plasma were measured by immunoassay. Significant hypomethylation of LINE-1 was observed in PBMCs from JSLE patients (60.93% in cases compared with 62.88% in controls, P = 0.001). Significant LINE-1 hypomethylation was observed in active SLE compared to controls (60.66% vs. 62.88%, P = 0.001). According to other clinical parameters, a significant correlation was found between LINE-1 methylation levels and the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2000) of the cases (r = -0.285, P = 0.032). The risk of JSLE increased with decreasing levels of LINE-1 methylation, with an odds ratio of 14.5 (95% CI: 2.8-75.6, P = 0.002). Cases had significantly higher plasma concentrations of tHcy than controls (15.11 vs. 11.02 μmol/L, P = 0.028); the correlation between LINE-1 methylation levels and tHcy was significant (r = -0.4, P = 0.013). Correlations between methylation levels of LINE-1 and complement component 3 were significant (r = 0.317, P = 0.044; r = 0.387, P = 0.031, in total JSLE and active JSLE, respectively). Hypomethylation of LINE-1 is associated with risk of JSLE, and LINE-1 methylation levels were related to disease activity and clinical manifestations. The correlation between tHcy levels and LINE-1 methylation was significant.

Dietary protein and plasma total homocysteine, cysteine concentrations in coronary angiographic subjects

BackgroundDietary patterns are associated with plasma total homocysteine (tHcy) concentrations in healthy populations, but the associations between dietary protein and tHcy, total cysteine (tCys) in high risk populations are unclear. We therefore examined the association between dietary protein and tHcy and tCys concentrations in coronary angiographic subjects.MethodsWe conducted a cross-sectional study of 1015 Chinese patients who underwent coronary angiography (40–85 y old). With the use of food-frequency questionnaires, we divided the total protein intakes into high animal-protein and high plant-protein diets. Circulating concentrations of tHcy and tCys were simultaneously measured by high-performance liquid chromatography with fluorescence detection.ResultsWe found that high animal-protein diet was positively associated with hyperhomocysteinemia after adjustment for potential confounders, with the subjects in the highest quartile of intake having the greatest increase in risk (OR: 4.14, 95% CI: 2.67-6.43), whereas high plant-protein diet was inversely related to hyperhomocysteinemia, with a higher intake being protective. Compared with the first quartile of intake, the adjusted OR was 0.59 (95% CI: 0.38-0.91) for the fourth quartile. The total protein intake was positively associated with the risk of hypercysteinemia and the participants in highest quartile had significant OR of 1.69 (95% CI: 1.02-2.87) compared with those in lowest quartile. In multivariate linear regression analyses, high animal-protein and total-protein intakes were positively associated with plasma tHcy and tCys concentrations. The plant-protein intake was a negative determinant of plasma tHcy concentrations.ConclusionsHigh animal-protein diet was positively associated with high tHcy concentrations, whereas high plant-protein diet was inversely associated with tHcy concentrations. Furthermore the total protein intake was strongly related to tCys concentrations.

Fracture is additionally attributed to hyperhomocysteinemia in men and premenopausal women with type 2 diabetes.

Data on hyperhomocysteinemia in relation to fractures in diabetes are limited. We aimed to explore the relationship between plasma total homocysteine concentrations and fractures in men and premenopausal women with type 2 diabetes. Diabetic and control participants (n=292) were enrolled in a cross-sectional hospital-based study. Bone mineral density and fractures were documented by dual energy X-ray absorptiometry and X-ray film, respectively. Plasma total homocysteine concentrations were measured using fluorescence polarization immunoassay. Risk factors for low bone mineral density or fractures and determinants of homocysteine were obtained from blood samples and the interviewer questionnaire. Plasma total homocysteine levels were higher in diabetic participants with fractures than without (8.6 [2.1]μmol/L vs 10.3 [3.0]μmol/L, P=0.000). Diabetic participants with fractures had similar bone mineral densities as control participants. The association of homocysteine with the fracture was independent of possible risk factors for fractures (e.g., age, duration of diabetes, glycated hemoglobin, body mass index, thiazolidenediones and retinopathy) and determinants of homocysteine concentration (e.g., age, sex, serum folate and vitamin B12, renal status and biguanide use; odds ratio 1.41, 95% confidence interval 1.05-2.03, P=0.020). Furthermore, per increase of 5.0μmol/L plasma homocysteine was related to the fracture, after controlling for per unit increase of other factors (odds ratio 1.42, 95% confidence interval 1.12-1.78, P=0.013). Plasma total homocysteine concentration is independently associated with occurrence of fractures in men and premenopausal women with type 2 diabetes. Future prospective studies are warranted to clarify the relationship.

The Metabolic Burden of Methyl Donor Deficiency with Focus on the Betaine Homocysteine Methyltransferase Pathway

Methyl groups are important for numerous cellular functions such as DNA methylation, phosphatidylcholine synthesis, and protein synthesis. The methyl group can directly be delivered by dietary methyl donors, including methionine, folate, betaine, and choline. The liver and the muscles appear to be the major organs for methyl group metabolism. Choline can be synthesized from phosphatidylcholine via the cytidine-diphosphate (CDP) pathway. Low dietary choline loweres methionine formation and causes a marked increase in S-adenosylmethionine utilization in the liver. The link between choline, betaine, and energy metabolism in humans indicates novel functions for these nutrients. This function appears to goes beyond the role of the nutrients in gene methylation and epigenetic control. Studies that simulated methyl-deficient diets reported disturbances in energy metabolism and protein synthesis in the liver, fatty liver, or muscle disorders. Changes in plasma concentrations of total homocysteine (tHcy) reflect one aspect of the metabolic consequences of methyl group deficiency or nutrient supplementations. Folic acid supplementation spares betaine as a methyl donor. Betaine is a significant determinant of plasma tHcy, particularly in case of folate deficiency, methionine load, or alcohol consumption. Betaine supplementation has a lowering effect on post-methionine load tHcy. Hypomethylation and tHcy elevation can be attenuated when choline or betaine is available.