Homocysteine as a risk factor for atherosclerosis

Homocysteine affects macrophage polarization by altering m6A methylation of scavenger receptors CD209 and CD163L1

Atherosclerosis is a chronic inflammatory disease characterized by fatty plaque deposits on artery walls. Elevated plasma homocysteine (Hcy) levels are an independent risk factor for atherosclerosis. Research on the mechanism by which Hcy promotes atherosclerosis has gradually turned to epigenetic inheritance, but the correlation between Hcy and m6A (N6-methyladenosine) modification has not been reported. In this study, MeRIP-seq was performed on macrophages and Hcy-treated macrophages. GO and KEGG analyses were used to perform functional analysis of differentially methylated genes. qRT-PCR and western blot were taken to determine the expression of CD209, CD163L1, proinflammatory, and anti-inflammatory factors. Flow cytometry was used to detect the proportion of M2 macrophages. The results showed that after Hcy treatment, the overall m6A methylation of macrophages was down-regulated, and 856 differential methylation peaks were annotated to 781 genes. These included CD209 and CD163L1, whose m6A methylation was inhibited after treatment with Hcy. In addition, mRNA and protein expressions of CD209 and CD163L1 were also inhibited after Hcy treatment. Overexpression of CD209 or CD163L1 prevents the Hcy-induced decrease in the proportion of M2 macrophages. This article identified changes in the modification level of m6A in macrophages by Hcy and revealed the possible mechanism by which Hcy induces macrophage polarization.

The Association of Vitamin B-12 Plasma Concentration with Stroke Incidence According to Sex

BACKGROUND

Previous studies reported that vitamin B-12 deficiency is associated with an increased risk of stroke. However, studies examining the association between excessive vitamin B-12 and stroke risk are limited. Our study aimed to investigate the relationship between excessive vitamin B-12 concentrations and risk of stroke and explore whether this association varies according to sex.

METHODS

Utilizing the Korean Genome Epidemiology Study (KoGES) prospective cohort data, our primary exposure variables were vitamin B-12 plasma concentration and sex. The occurrence of stroke served as the main outcome of interest. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression analysis. An interaction analysis was conducted to assess the interaction effect of vitamin B-12 and sex on stroke incidence.

RESULTS

Cox proportional logistic regression analysis, adjusting for confounders, showed that excessive vitamin B-12 did not significantly alter stroke risk (HR: 1.22, 95% CI: 0.82, 1.71) and revealed no significant sex-based differences in stroke risk (HR: 0.90, 95% CI: 0.75, 1.04). However, interaction analysis indicated that excessive vitamin B-12 was linked to a significant increase in stroke risk in males (HR: 1.81, 95% CI: 1.10, 2.99) but not in females (HR: 1.04, 95% CI: 0.66, 1.60), with statistically significant interaction effect (P < 0.01).

CONCLUSIONS

Our study demonstrated that although excessive vitamin B-12 alone does not significantly increase stroke risk, it increases risk in males when considering the interaction with sex.

Precision matters: Repeatability and reproducibility of total PSA and homocysteine measurements in Alinity i-system

Background

The precision of test measurements is critical in clinical diagnostics, especially for biomarkers like total PSA and homocysteine, which are essential to disease assessment. Using the CMIA approach, this study investigates the repeatability and reproducibility of these biomarkers on the Abbott Alinity system.

Methods

The present study was conducted in the clinical chemistry laboratory at Mohammed VI University Hospital of Oujda. The evaluation of the Alinity i-system's analytical performance for total PSA and homocysteine focused on assessing repeatability and intermediate precision. The assessment followed the protocols and guidelines established by the French Accreditation Committee (COFRAC).

Results

Our analysis yielded favorable findings regarding the performance of the Alinity assays. The coefficients of variation for both the within-run and between-run precision were less than 5.89% and 4.29%, respectively. These findings produce acceptable outcomes compared to the manufacturer's claims and the SFBC database. Our study underscores the tests' precision, affirming the CMIA method's reliability in measuring total PSA and homocysteine levels.

Conclusions

The assessment of the Alinity i-system for total PSA and homocysteine showed significant analytical performance. Our findings have implications for laboratory personnel, researchers, and physicians supporting a continuous diagnostic accuracy improvement culture.

Effectiveness and Safety of Fufang Danshen Dripping Pill (Cardiotonic Pill) on Blood Viscosity and Hemorheological Factors for Cardiovascular Event Prevention in Patients with Type 2 Diabetes Mellitus: Systematic Review and Meta-Analysis

Background and Objectives: Diabetes can cause various vascular complications. The Compounded Danshen-Dripping-Pill (CDDP) is widely used in China. This study aimed to analyze the effectiveness and safety of CDDP in the blood viscosity (BV) with type 2 diabetes mellitus (T2DM). Materials and Methods: We conducted a systematic search of seven databases from their inception to July 2022 for randomized controlled trials that used CDDP to treat T2DM. To evaluate BV, we measured low shear rate (LSR), high shear rate (HSR), and plasma viscosity (PV). Homocysteine and adiponectin levels were also assessed as factors that could affect BV. Results: We included 18 studies and 1532 patients with T2DM. Meta-analysis revealed that CDDP significantly reduced LSR (mean difference [MD] -2.74, 95% confidence interval [CI] -3.77 to -1.72), HSR (MD -0.86, 95% CI -1.08 to -0.63), and PV (MD -0.37, 95% CI -0.54 to -0.19) compared to controls. CDDP also reduced homocysteine (MD -8.32, 95% CI -9.05 to -7.58), and increased plasma adiponectin (MD 2.72, 95% CI 2.13 to 3.32). Adverse events were reported less frequently in the treatment groups than in controls. Conclusions: CDDP is effective in reducing BV on T2DM. However, due to the poor design and quality of the included studies, high-quality, well-designed studies are required in the future.

Stroke in Parkinson's disease: a review of epidemiological studies and potential pathophysiological mechanisms

Parkinson's disease (PD) is the fastest growing neurological disorder and one of the leading neurological causes of disability worldwide following stroke. An overall aging global population, as well as general changes in lifestyle associated with mass industrialization in the last century, may be linked to both increased incidence rates of PD and an increase in cumulative cardiovascular risk. Recent epidemiological studies show an increased risk of stroke, post-stroke complications, and subclinical ischemic insults in PD. PD patients have a host of characteristics that might contribute to increasing the risk of developing ischemic stroke including motor impairment, dysautonomia, and sleep disorders. This increases the urgency to study the interplay between PD and other neurological disorders, and their combined effect on mortality, morbidity, and quality of life. In this review, we provide a comprehensive overview of the studied etiological factors and pathological processes involved in PD, specifically with regard to their relationship to stroke. We hope that this review offers an insight into the relationship between PD and ischemic stroke and motivates further studies in this regard.

Research progress on risk factors related to intracranial artery, carotid artery, and coronary artery stenosis

In recent decades, with the rapid development of economy, the acceleration of social aging and urbanization, and the prevalence of unhealthy lifestyles, the number of patients with cardiovascular and cerebrovascular diseases has shown an increasing trend year by year. It has also become one of the important causes of disability and death in all ages and groups. Atherosclerosis is the main pathological change of ischemic cardiovascular and cerebrovascular diseases, which mainly invades the large and medium arteries of the body circulation. In particular, cerebral artery and coronary artery lesions have the most significant impact on life. There is the same pathogenic mechanism between intracranial and extracranial arteries and coronary atherosclerosis, so there is a certain relationship between the degree of atherosclerosis. In this paper, the risk factors related to intracranial and extracranial arteries and coronary artery stenosis were reviewed. It provides a theoretical basis for early detection, early diagnosis and early treatment of intracranial and extracranial artery and coronary artery stenosis to reduce the occurrence and development of cardiovascular and cerebrovascular diseases.

Association Between Parkinson's Disease and Coronary Artery Disease: A Systematic Review and Meta-Analysis

BACKGROUND

The relationship between Parkinson's disease (PD) and coronary artery disease (CAD) is unclear.

OBJECTIVE

This study aims to investigate whether PD and CAD are associated through systematic review and meta-analysis of observational studies.

METHODS

Electronic database search of PubMed, EMBASE, and Web of Science for observational studies published from 1 January 2010 to 1 August 2021 was conducted using terms related to PD and CAD. Unadjusted risk ratios (RR) and odds ratios (OR) of included cohort and case-control studies respectively were used to ascertain the association between PD and CAD. Study heterogeneity was evaluated using the I2 test.

RESULTS

Forty-one full-text studies were initially retrieved for eligibility assessment. Five studies that satisfied the inclusion criteria, consisting of three cohort and two case-control studies, were eventually included in this meta-analysis. The five studies enrolled 35,237 PD patients and 650,866 non-PD patients. PD and CAD were found to be significantly associated in cohort studies (RR = 2.23, 95% CI = 1.08-4.59, p = 0.03; Fig. 2), which held after sensitivity analysis (RR = 1.45, 95% CI = 1.31-1.60, p < 0.001; Fig. 3). Case-control studies found a trend towards association of PD and CAD approaching significance (OR = 1.47, 95% CI = 0.84-2.56, p = 0.18; Fig. 2).

CONCLUSION

Overall, this meta-analysis suggests that PD is associated with CAD. The underlying mechanisms, as well as the role of ethnicity and other comorbidities on the relationship between PD and CAD should be further explored.

Elevated homocysteine level as an indicator for chronic kidney disease in community-dwelling middle-aged and elderly populations in Taiwan: A community-based cross-sectional study

Background

Hyperhomocysteinemia is an important factor for endothelial cell damage and a risk factor for cardiovascular diseases. Chronic kidney disease (CKD) is recognized as a leading burden in Taiwan’s healthcare system. This study aimed to investigate the association between homocysteine levels and CKD in middle-aged and elderly adults from a community in northern Taiwan.

Methods

A total of 396 middle-aged and elderly Taiwanese adults were enrolled and completed the health survey. We divided participants according to tertiles of homocysteine levels as first group (homocysteine level ≤ 11.1 μmol/L), second group (homocysteine level 11.2∼14.3 μmol/L), and third group (homocysteine level > 14.3 μmol/L). CKD was defined as estimated glomerular filtration rate (eGFR) < 60 (mL/min/1.73 m²) or urine albumin to creatinine ratio > 30 (mg/g). Pearson correlation was calculated between eGFR and other related risk factors after adjustment for age. The risk of CKD in the second and third groups compared to that in the first group was assessed by multivariate logistic regression after adjustment for age, sex, smoking, hypertension (HTN), diabetes mellitus (DM), body mass index (BMI), dyslipidemia, and uric acid. The Youden index and receiver operating characteristic (ROC) curve were calculated for the optimized cutoff value.

Results

Elevated plasma homocysteine levels were more likely to lower the eGFR and increase the prevalence of CKD. Pearson correlation showed a positive correlation between eGFR and high-density lipoprotein cholesterol, while a negative correlation was observed between homocysteine levels, waist circumference, systolic blood pressure, uric acid levels and BMI (all p < 0.05). In the logistic regression analysis, the prevalence of CKD increased, as well as the homocysteine level. The odds ratio of CKD under 95% confidence interval was 2.655 (1.284–5.490) for the third group compared with the first group after adjusting for age, sex, smoking, DM, HTN, dyslipidemia, uric acid, and BMI (p = 0.008). The area under the ROC curve was 0.662, and a cutoff value of 15.15 μmol/L for the homocysteine level was obtained for detecting subjects with CKD.

Conclusion

Our study findings revealed that elevated homocysteine levels were significantly associated with CKD and could be used as an indicator of CKD among the middle-aged and elderly populations in Taiwan.

Prevalence of Hyperhomocysteinemia in China: An Updated Meta-Analysis

Simple Summary

Hyperhomocysteinemia has been defined as an elevated serum concentration of homocysteine exceeding 15 μmol/L and has been proven to play an important role in the pathogenesis of cerebrovascular disease. The prevalence of hyperhomocysteinemia in China has been outlined in a previous meta-analysis. Considering the key role of homocysteine in the process of vascular injury, more studies have been conducted to prevent hyperhomocysteinemia by nutritional supplements such as folic acid or other treatments. Additionally, studies have shown that the prevalence of hyperhomocysteinemia increases over time; therefore, it was necessary to provide an update from the previous meta-analysis on homocysteine status in China. This was needed to understand the prevalence, the trend in changes over time, and its determinants. The results highlight that the prevalence of hyperhomocysteinemia is increasing in China, especially among the elderly, men, and residents in the north, inland areas, and rural areas of China.

Abstract

We conducted a meta-analysis to systematically assess the prevalence of hyperhomocysteinemia (HHcy) in China, its change over time, and its determinants. Literature searches were conducted using English databases (PubMed, Embase, and Web of Science) and Chinese databases (CNKI, CBM, VIP, and Wanfang). The time ranges were from Jan 2014 to Mar 2021 in China. We adopted the random effects model to estimate the pooled positive rates of HHcy and corresponding 95% confidence intervals (95% CI). To find the sources of heterogeneity, we performed subgroup analysis and meta-regression. A total of 29 related articles were identified involving 338,660 participants with 128,147 HHcy cases. The estimated prevalence of HHcy in China was 37.2% (95% CI: 32.6–41.8%, I² = 99.8%, p for heterogeneity < 0.001). The trend of HHcy prevalence was gradually upward over time, with increases during 2015–2016 (comparison to 2013–2014, p < 0.001), but steady between 2015–2016 and 2017–2018. Subgroup analysis showed that the prevalence was higher in the elderly over 55 years old, males, and residents in the north, inland, and rural China (for each comparison, p < 0.001). Meta-regression analysis revealed that age and area of study contributed to 42.3% of the heterogeneity between studies. The current meta-analysis provides strong evidence that the prevalence of HHcy is increasing in China, and varies substantially across different ages, genders, and geographic distribution. Accordingly, high-risk population groups should be focused on, and public health policies and strategies should be carried out to prevent and control HHcy in China.

Melatonin as a Reducer of Neuro- and Vasculotoxic Oxidative Stress Induced by Homocysteine

The antioxidant properties of melatonin can be successfully used to reduce the effects of oxidative stress caused by homocysteine. The beneficial actions of melatonin are mainly due to its ability to inhibit the generation of the hydroxyl radical during the oxidation of homocysteine. Melatonin protects endothelial cells, neurons, and glia against the action of oxygen radicals generated by homocysteine and prevents the structural changes in cells that lead to impaired contractility of blood vessels and neuronal degeneration. It can be, therefore, assumed that the results obtained in experiments performed mainly in the in vitro models and occasionally in animal models may clear the way to clinical applications of melatonin in patients with hyperhomocysteinemia, who exhibit a higher risk of developing neurodegenerative diseases (e.g., Parkinson’s disease or Alzheimer’s disease) and cardiovascular diseases of atherothrombotic etiology. However, the results that have been obtained so far are scarce and have seldom been performed on advanced in vivo models. All findings predominately originate from the use of in vitro models and the scarcity of clinical evidence is huge. Thus, this mini-review should be considered as a summary of the outcomes of the initial research in the field concerning the use of melatonin as a possibly efficient attenuator of oxidative stress induced by homocysteine.

Sulfur-Containing Amino Acids and Lipid Metabolism

The metabolism of methionine and cysteine in the body tissues determines the concentrations of several metabolites with various biologic activities, including homocysteine, hydrogen sulfide (H2S), taurine, and glutathione. Hyperhomocysteinemia, which is correlated with lower HDL cholesterol in blood in volunteers and animal models, has been associated with an increased risk for cardiovascular diseases. In humans, the relation between methionine intake and hyperhomocysteinemia is dependent on vitamin status (vitamins B-6 and B-12 and folic acid) and on the supply of other amino acids. However, lowering homocysteinemia by itself is not sufficient for decreasing the risk of cardiovascular disease progression. Other compounds related to methionine metabolism have recently been identified as being involved in the risk of atherosclerosis and steatohepatitis. Indeed, the metabolism of sulfur amino acids has an impact on phosphatidylcholine (PC) metabolism, and anomalies in PC synthesis due to global hypomethylation have been associated with disturbances of lipid metabolism. In addition, impairment of H2S synthesis from cysteine favors atherosclerosis and steatosis in animal models. The effects of taurine on lipid metabolism appear heterogeneous depending on the populations of volunteers studied. A decrease in the concentration of intracellular glutathione, a tripeptide involved in redox homeostasis, is implicated in the etiology of cardiovascular diseases and steatosis. Last, supplementation with betaine, a compound that allows remethylation of homocysteine to methionine, decreases basal and methionine-stimulated homocysteinemia; however, it adversely increases plasma total and LDL cholesterol. The study of these metabolites may help determine the range of optimal and safe intakes of methionine and cysteine in dietary proteins and supplements. The amino acid requirement for protein synthesis in different situations and for optimal production of intracellular compounds involved in the regulation of lipid metabolism also needs to be considered for dietary attenuation of atherosclerosis and steatosis risk.

Homocysteine might increase the risk of recurrence in patients presenting with primary cerebral infarction

PURPOSE

Although hyperhomocysteinemia (Hhcy) is a risk factor for cerebral infarction, its effect on recurrent cerebral infarction is less-defined. We aimed to investigate the association of Hhcy and increased risk of recurrent cerebral infarct.

MATERIALS AND METHODS

From 2011 to 2013, we recruited 231 primary cerebral infarct patients that were divided to a Hhcy group (n = 105) and a control group (n = 126) according to plasma homocysteinemia (Hcy) levels exceeding 15 μmol/L. In this prospective study, risk factors such as gender, age, blood lipid and glucose levels, history of diabetes, high blood pressure, smoking habits and plasma Hhcy levels were determined. A three-year follow-up compared differences in cerebral infarction recurrence rates. Statistical analyses identified whether plasma Hhcy levels were an independent risk factor for recurrent cerebral infarction.

RESULTS

Triglyceride and low-density lipoprotein (LDL) levels in the Hhcy group were significantly higher than controls, and cerebral infarct recurrence rates in the Hhcy group exceeded control subject rates through the three-year follow-up (p = .021, p = .036 and p = .025). Cox proportional hazards modeling showed that elevated Hhcy levels (hazard ratio [HR] = 3.062, p < .001), increased age (HR = 1.069, p < .01), circulating triglyceride levels (HR = 1.686, p = .048), and relative National Institutes of Health Stroke (NIHSS) score (HR = 1.068, p = .016) were risk factors for recurrent cerebral infarction.

CONCLUSIONS

Level of Hhcy was a risk factor for recurrent cerebral infarction. Further, particular demographic and clinical outcomes including age, relative NIHSS scores, and circulating triglyceride levels were markedly associated with the occurrence of cerebral infarction.

Association Between Folic Acid Supplementation and Retinal Atherosclerosis in Chinese Adults With Hypertension Complicated by Diabetes Mellitus

Background: This cross-section investigation included 2,199 participants with hypertension complicated by diabetes mellitus, a cohort of the China Stroke Primary Prevention Trial in which 20,702 patients with essential hypertension were given enalapril with folic acid or enalapril-only double-blind treatment for 5 years. This study aimed to explore the correlation between folic acid supplementation and retinal atherosclerosis (RA) in adults with hypertension complicated by diabetes mellitus.

Methods: The diagnosis of RA was determined by non-mydriatic fundus photography and classified by the Keith-Wagener-Barker system. The statistical correlation of folic acid supplementation with RA prevalence and severity was assessed.

Results: Of our cohort, 1,698 (77.6%) participants were diagnosed with RA, and the prevalence in males and females was 78.0 and 75.6%, respectively. Participants in the enalapril group had higher total homocysteine (tHcy) levels than those in enalapril–folic acid group. Compared with the enalapril group in the tHcy > 15 μmol/L group of females, the odds ratio for the enalapril–folic acid group was 0.28 (95% confidence interval, 0.11–0.67, P = 0.0061).

Conclusions: The prevalence of RA was high (77.6%) in our cohort of adults with hypertension complicated by diabetes mellitus. Folic acid supplementation was significantly associated with reduced risk of RA in females with hyperhomocysteinemia. No significant association were seen in males.

Prevalent cerebrovascular and cardiovascular disease in people with Parkinson's disease: a meta-analysis

Background

People with Parkinson's disease (PwP) are speculated to be at a low risk of cerebrovascular and cardiovascular disease (CVD) because they have fewer vascular risk factors and lower smoking rate. However, emerging evidence suggests that PwP are at higher risk of CVD, which introduces controversy to the notion that there is no association between Parkinson's disease (PD) and CVD. Hence, we conducted a meta-analysis to analyze the risk of CVD in PwP.

Methods

Electronic databases were searched using terms related to PD and CVD. Articles were included in the meta-analysis only if they employed clear diagnostic criteria for PD and CVD. The reference lists of the relevant articles were reviewed to identify eligible studies not found during the keyword search.

Results

The enrolled studies were categorized into case-control and cohort studies, and the former was further divided into postmortem (three) and clinical (four) studies. In the clinical case-control studies group, PD was more associated with CVD (OR: 2.89, 95% CI: 1.36-6.13). Three studies were enrolled in the cohort studies group, and the merged results demonstrated that PwP were at higher risk of CVD during the follow-up period (HR: 1.84, 95% CI: 1.34-2.54).

Conclusion

PD is associated with CVD, which may be due to the shared pathogeneses between the two diseases or PD-related effects. PwP should be more aware of the risk of CVD despite having fewer traditional vascular risk factors.

Saliva/serum ghrelin, obestatin and homocysteine levels in patients with ischaemic heart disease

BACKGROUND

We aimed to compare ghrelin, obestatin, homocysteine (Hcy), vitamin B₁₂ and folate levels in the serum and saliva of ischaemic heart disease patients.

METHODS

Serum and saliva were collected from 33 ischaemic heart disease (IHD) patients and 28 age- and body mass index-matched healthy individuals. Levels of acylated and desacylated ghrelin, obestatin and Hcy were determined using the ELISA method.

RESULTS

Acylated ghrelin, desacylated ghrelin and obestatin levels in the saliva were found to be higher than those in the serum of the control group, while acylated and desacylated ghrelin levels in the saliva were significantly lower than those in the serum. Obestatin levels were higher in IHD patients (p = 0.001). Saliva and serum vitamin B₁₂ and folate levels in IHD patients were significantly lower than in the control group (p = 0.001).

CONCLUSIONS

It was determined that serum ghrelin levels increased in ischaemic heart disease patients, while serum levels of obestatin decreased.

Association of homocysteine level and vascular burden and cognitive function in middle-aged and older adults with chronic kidney disease

OBJECTIVES

Patients with chronic kidney disease (CKD) have been found to have cognitive impairment. However, the core features and clinical correlates of cognitive impairment are still unclear. Elevated homocysteine levels are present in CKD, and this is a risk factor for cognitive impairment and vascular diseases in the general population. Thus, this study investigated the core domains of cognitive impairment and investigated the associations of homocysteine level and vascular burden with cognitive function in patients with CKD.

METHODS

Patients with CKD aged ≥ 50 years and age- and sex-matched normal comparisons were enrolled. The total fasting serum homocysteine level was measured. Vascular burden was assessed using the Framingham Cardiovascular Risk Scale. Cognitive function was evaluated using comprehensive neuropsychological tests.

RESULTS

A total of 230 patients with CKD and 92 comparisons completed the study. Memory impairment and executive dysfunction were identified as core features of cognitive impairment in the CKD patients. Among the patients with CKD, higher serum homocysteine levels (β = -0.17, p = 0.035) and higher Framingham Cardiovascular Risk Scale scores (β = -0.18, p = 0.013) were correlated with poor executive function independently. However, an association with memory function was not noted. Our results showed that an elevated homocysteine level and an increased vascular burden were independently associated with executive function, but not memory, in CKD patients.

CONCLUSIONS

This findings suggested the co-existence of vascular and non-vascular hypotheses regarding executive dysfunction in CKD patients. Meanwhile, other risk factors related to CKD itself should be investigated in the future. Copyright © 2015 John Wiley & Sons, Ltd.

Spinal cord demyelination combined with hyperhomocysteinemia: a case report

Hyperhomocysteinemia (HHcy) has been recognized as an independent risk factor for atherosclerotic vascular disease. Here we report a patient who suffered from spinal cord demyelination combined with HHcy. The patient was admitted to our hospital with a diagnosis of acute myelitis. However, hormone therapy was ineffective. Further investigations revealed that he had HHcy and a homozygous mutation of the gene encoding methylenetetrahydrofolate reductase (MTHFR) c.677C>T, which is a key enzyme involved in homocysteine metabolism. In view of these findings, we treated the patient with B vitamins and his symptoms gradually improved. Spinal magnetic resonance imaging performed 3 months after onset showed near recovery of the lesion. To our knowledge, similar reports are rare.

Metabolic and endocrine effects of valproic acid chronic treatment

Treatment of epileptic patients with valproic acid (VPA) may be associated with substantial weight changes that may increase morbidity and impair adherence to the treatment regimen. VPA-induced weight gain seems to be associated with many metabolic disturbances; the most frequent are hyperinsulinemia and insulin resistance, hyperleptinemia and leptin resistance. Patients who gain weight during VPA therapy can develop dyslipidemia and metabolic syndrome that are associated with long-term vascular complications such as hypertension and atherosclerosis. Moreover, an elevation in the levels of uric acid and homocysteine, together with oxidative stress, may contribute to atherosclerotic risk in patients under long-term therapy with VPA. The aim of this review is to discuss the metabolic and endocrine effects of VPA chronic treatment in patients with epilepsy.

Elevated homocysteine levels in levodopa-treated idiopathic Parkinson's disease: a meta-analysis

To assess the association between the elevation of plasma homocysteine (Hcy) level and long-term levodopa (L-dopa) therapy in idiopathic Parkinson's disease (PD). We performed a systematic literature review to recruit original studies published up to May 14, 2012. Studies enrolled should be controlled, with specific information of long-term L-dopa application and plasma Hcy in patients with PD. Effects were summarized using standardized mean differences (SMDs) or weighted mean differences (WMDs). Our search enrolled 22 eligible studies. Plasma Hcy levels were significantly higher in L-dopa-treated patients than those in healthy controls [SMD 0.97; 95% confidence interval (CI) 0.80-1.14, P < 0.001], L-dopa-naïve patients with PD (SMD 0.99; 95% CI 0.54-1.44, P < 0.001), and untreated patients (SMD 0.52; 95% CI 0.18-0.86, P < 0.01). However, its levels in untreated patients with PD were not significantly higher than in healthy controls (SMD 0.24; 95% CI -0.03 to 0.51, P > 0.05). Patients with PD treated with L-dopa plus catechol-O-methyltransferase inhibitor (COMT-I) showed lower plasma Hcy concentrations compared with L-dopa-treated patients (WMD 4.62; 95% CI 2.89-6.35, P < 0.001). L-dopa treatment is associated with the increase in plasma Hcy level in patients with PD. COMT-I may attenuate L-dopa-induced elevation of Hcy level.

Association between MTHFR C677T polymorphism and primary open-angle glaucoma: a meta-analysis

Epidemiological studies have evaluated the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and primary open-angle glaucoma (POAG) risk. However, the results remain conflicting. The aim of this study was to investigate the association between MTHFRC677T polymorphism and POAG risk. All genetic association studies on MTHFR C677T polymorphism and POAG were systematically searched by the electronic databases PubMed, Embase and Web of Science. Study selection, data abstraction and study quality evaluation were conducted in duplicate independently. The strength of association between MTHFR C677T polymorphism and POAG was measured by odds ratios (ORs) and 95% confidence intervals (CIs). Publication bias was tested by Begg's funnel plot and Egger's regression test. A total of 10 studies including 1224 cases and 1105 controls were included in our final meta-analysis. There was no evidence of significant association of the overall population (for allelic model: OR=1.17, 95% CI=0.94-1.46; for additive model: OR=1.15, 95% CI=0.85-1.57; for dominant model: OR=1.19, 95% CI=0.92-1.55 and for recessive model: OR=1.11, 95% CI=0.83-1.49). Significant associations were found between MTHFR C677T polymorphisms and POAG in allelic model (OR=1.39, 95% CI=1.05-1.83) and additive model (OR=1.88, 95% CI=1.04-3.43) for population-based (PB) subgroup. This meta-analysis suggested that there were significant associations between MTHFR C677T polymorphism and POAG in allelic model and additive model for PB subgroup which indicated that the T allele or TT genotype might increase the risk of POAG, whereas no evidence of significant association was shown of the overall studied population. However, this conclusion should be interpreted cautiously. More large sample-size and multi-ethnicity studies with well-defined POAG patients and well-study design are needed in the future study.

Calpain activation is required for homocysteine-mediated hepatic degradation of inhibitor I kappa B alpha

Hepatic steatosis is a clinical feature observed in severe hyperhomocysteinemic patients. In mice, cystathionine beta synthase (CBS) deficiency, the most common cause of severe hyperhomocysteinemia, is also associated with steatosis, fibrosis and inflammation. Proinflammatory cytokines usually induce apoptosis. However, hyperhomocysteinemia does not increase apoptosis in liver of CBS-deficient mice compared to wild type mice. The aim of the study was to analyze the activation state of the NF-kappaB pathway in liver of CBS-deficient mice and to investigate its possible involvement in anti-apoptotic signals. We analyzed the level of I kappaB alpha in liver of CBS-deficient mice. A co-culture of primary hepatocytes and Kupffer cells was also used in order to investigate how I kappaB alpha degradation occurs in response to homocysteine. We found lower I kappaB alpha level not only in liver of CBS-deficient mice but also in hepatocyte/Kupffer cell co-culture. The homocysteine-mediated I kappaB alpha enhanced proteolysis occurred via calcium-dependent calpains, which was supported by an increased level of calpain activity and a reduced expression of calpastatin in liver of CBS-deficient mice. Intraperitoneal administration of the inhibitor PDTC normalized the expression of two genes induced by NF-kappaB activation, heme oxygenase-1 and cellular inhibitor of apoptosis 2. Moreover, PDTC administration induced an increase of caspase-3 activity in liver of CBS-deficient mice. Our results suggest that hyperhomocysteinemia induces calpain-mediated I kappaB alpha degradation which is responsible for anti-apoptotic signals in liver.

Long-term antiepileptic drug therapy contributes to the acceleration of atherosclerosis

PURPOSE

Long-term antiepileptic drug (AED) therapy has been associated with an increase in risk of atherosclerosis. At issue is whether this risk is related to the duration of AED therapy. We evaluated the hypothesis that the cumulative effect of long-term exposure to AEDs plays a pivotal role in the pathogenesis of atherosclerosis in patients with epilepsy.

METHODS

One hundred ninety-five patients under long-term AED therapy and 195 healthy age- and sex-matched control subjects received measurement of intima media thickness (IMT) at the far wall of the common carotid artery (CCA) by B-mode ultrasonography to assess the extent of atherosclerosis. Other measurements included body mass index (BMI) and blood lipid profile or homocysteine, folic acid, uric acid, fasting blood sugar, high sensitivity C-reactive protein (hs-CRP), thiobarbituric acid reactive substances (TBARS), and total reduced thiols.

RESULTS

CCA IMT was significantly increased in patients with epilepsy, with male subjects exhibiting thicker IMT than their female counterparts. Whereas BMI, homocysteine, hs-CRP, and TBARS were significantly elevated, folic acid and thiols were significantly reduced in patients with epilepsy. Multiple linear regression analysis further revealed that duration of AED therapy, age, gender, and TBARS level (index for oxidative stress) were independently associated with CCA IMT. In addition, the log-transformed CCA IMT increased linearly with duration of AED therapy after adjustments for age, gender, and TBARS level.

DISCUSSION

The duration of AED therapy is significantly associated with the acceleration of atherosclerosis in patients with epilepsy, alongside independent contributions of age, gender, and oxidative stress to the atherosclerotic process.

Effects of red wine polyphenolic compounds on paraoxonase-1 and lectin-like oxidized low-density lipoprotein receptor-1 in hyperhomocysteinemic mice

Hyperhomocysteinemia, or abnormally high plasma homocysteine (Hcy) concentration, has often been associated with vascular thrombosis and the development of premature atherosclerosis. Many studies have shown that moderate wine consumption has potential beneficial effects related to the prevention of atherosclerosis, in part attributed to the biological properties of polyphenolic components, mainly flavonoids. The aim of the present study is to determine the effects of a red wine polyphenolic extract (PE) administration on hyperhomocysteinemia due to cystathionine beta-synthase (CBS) deficiency and on the associated biochemical markers of hepatic and endothelial dysfunctions in mice. Red wine PE was added for 4 weeks to the drinking water of heterozygous CBS-deficient mice fed a high-methionine diet, a murine model of hyperhomocysteinemia. Red wine PE supplementation at low dose significantly reduced plasma Hcy levels and restored the hepatic and plasma-decreased paraoxonase-1 activity induced by chronic hyperhomocysteinemia. Moreover, aortic expression of proinflammatory cytokines and adhesion molecules and levels of soluble lectin-like oxidized low-density lipoprotein receptor-1 were reduced in hyperhomocysteinemic mice fed the red wine PE supplementation. These findings suggest that red wine PE administration in low quantities has beneficial effects on biochemical markers of endothelial dysfunction due to hyperhomocysteinemia.

Cystathionine beta synthase deficiency induces catalase-mediated hydrogen peroxide detoxification in mice liver

Cystathionine beta synthase deficiency induces hyperhomocysteinemia which is considered as a risk factor for vascular diseases. Studies underlined the importance of altered cellular redox reactions in hyperhomocysteinemia-induced vascular pathologies. Nevertheless, hyperhomocysteinemia also induces hepatic dysfunction which may accelerate the development of vascular pathologies by modifying cholesterol homeostasis. The aim of the present study was to analyze the modifications of redox state in the liver of heterozygous cystathionine beta synthase-deficient mice, a murine model of hyperhomocysteinemia. In this purpose, we quantified levels of reactive oxygen and nitrogen species and we assayed activities of main antioxidant enzymes. We found that cystathionine beta synthase deficiency induced NADPH oxidase activation. However, there was no accumulation of reactive oxygen (superoxide anion, hydrogen peroxide) and nitrogen (nitrite, peroxynitrite) species. On the contrary, hepatic hydrogen peroxide level was decreased independently of an activation of glutathione-dependent mechanisms. In fact, cystathionine beta synthase deficiency had no effect on glutathione peroxidase, glutathione reductase and glutathione S-transferase activities. However, we found a 50% increase in hepatic catalase activity without any variation of expression. These findings demonstrate that cystathionine beta synthase deficiency initiates redox disequilibrium in the liver. However, the activation of catalase attenuates oxidative impairments.

IMMULITE 2000 age and sex-specific reference intervals for alpha fetoprotein, homocysteine, insulin, insulin-like growth factor-1, insulin-like growth factor binding protein-3, C-peptide, immunoglobulin E and intact parathyroid hormone

OBJECTIVES

To determine age and sex-specific pediatric reference intervals for serum alpha fetoprotein, homocysteine, insulin, insulin-like growth factor-I, insulin-like growth factor binding protein-3, C-peptide, immunoglobulin E and parathyroid hormone.

DESIGN AND METHODS

The study was conducted at both Children's National Medical Center and Georgetown University, Washington D.C. Results for the above analytes were obtained from the Children's National Medical Center laboratory information system over the period of 1/5/2001-3/8/2007. Patient results using the IMMULITE 2000(R) were accessed and used to establish reference intervals for the analytes studied. All patient identifiers were removed except age and sex. Analysis of the data was performed at Georgetown University in the Bioanalytical Core Laboratory. The data was analyzed using the Hoffmann approach, and was computer adapted. The number of patient samples studied varied with each analyte and were: Alpha fetoprotein (557), homocysteine (924), insulin-like growth factor-1 (1352), insulin-like growth factor binding protein-3 (711), insulin (3239), C-peptide (267), immunoglobulin E (2691) and parathyroid hormone (513).

RESULTS AND CONCLUSIONS

This study provides pediatric reference intervals for the eight analytes for children from birth to 18 years of age. All the analytes exhibited at least some age dependence. Sex differences between early and late childhood and adolescence were also frequently found.

Homocysteine levels in epileptic children receiving antiepileptic drugs

The aim of this study is to investigate the homocysteine, folic acid, and vitamin B(12) levels in epileptic children receiving antiepileptic drugs. A total of 25 children with idiopathic epilepsy (8 valproate, 11 carbamazepine, and 6 oxcarbazepine) and 10 healthy children were included in the study. The mean homocysteine, folic acid, and vitamin B(12) levels in the study group were 7.57 +/- 3.78 micromol/L (normal = 5-15 micromol/L), 10.19 +/- 4.05 ng/mL (normal = 3.0-17 ng/mL), and 428.20 +/- 256.12 pg/mL (normal = 193-983 pg/mL), respectively. The differences between the mean plasma homocysteine, folic acid, and vitamin B(12) levels of the study and control groups were not significant (P = .522; P = .855; P = .798, respectively). However, plasma homocysteine levels were higher than the normal cutoff point accepted for childhood in 4 (16%) of the study patients. Out of these 4 children, 3 were from the carbamazepine group and 1 was from the valproate group. Although the number of the study patients is limited, the authors recommend assessment of plasma homocysteine, serum vitamin B(12), and folic acid levels in children receiving enzyme-inducing antiepileptic drugs.

Homocysteine threshold value based on cystathionine beta synthase and paraoxonase 1 activities in mice

BACKGROUND

Hyperhomocysteinaemia is a metabolic disorder associated with the development of premature atherosclerosis. Among the determinants which predispose to premature thromboembolic and atherothrombotic events, serum activity of paraoxonase 1, mainly synthesized in the liver, has been shown to be a predictor of cardiovascular disease and to be negatively correlated with serum homocysteine levels in human. Even though treatments of hyperhomocysteinaemic patients ongoing cardiovascular complications are commonly used, it still remains unclear above which homocysteine level a preventive therapy should be started.

MATERIALS AND METHODS

In order to establish a threshold of plasma homocysteine concentration we have analyzed the hepatic cystathionine beta synthase and paraoxonase 1 activities in a moderate to intermediate murine model of hyperhomocysteinaemia. Using wild type and heterozygous cystathionine beta synthase deficient mice fed a methionine enriched diet or a control diet, we first studied the link between cystathionine beta synthase and paraoxonase 1 activities and plasma homocysteine concentration.

RESULTS

Among the animals used in this study, we observed a negative correlation between plasma homocysteine level and cystathionine beta synthase activity (rho=-0.52, P=0.0008) or paraoxonase 1 activity (rho=-0.49, P=0.002). Starting from these results, a homocysteine cut-off value of 15 microm has been found for both cystathionine beta synthase (P=0.0003) and paraoxonase 1 (P=0.0007) activities.

CONCLUSIONS

Our results suggest that both cystathionine beta synthase and paraoxonase 1 activities are significantly decreased in mice with a plasma homocysteine value greater than 15 microm. In an attempt to set up preventive treatment for cardiovascular disease our results indicate that treatments should be started from 15 microm of plasma homocysteine.

Folic acid and cognition in older persons

Folic acid supplementation has drawn much attention in recent years for the prevention of Alzheimer's disease and cognitive decline. In this review, the authors describe how current evidence does not support the use of folic acid supplements to protect against cognitive decline. Although a few studies suggest that folic acid supplementation may provide neuroprotection among persons who are folate deficient, there is also data to indicate that supplementation in persons without folate deficiency may pose a risk to neurological function. Vitamin B12 deficiency is common in old age and may not be easy to recognise. Folic acid supplementation may mask the anaemia associated with vitamin B12 deficiency and, therefore, may delay treatment while allowing progression of neurological symptoms. Whether or not folic acid supplementation exacerbates neurological symptoms of vitamin B12 deficiency is not clear. Further studies are needed to determine the possible risks and benefits of folic acid supplementation in older persons.

Homocysteine and Parkinson's disease: a dangerous liaison?

Homocysteine, a sulphur-containing amino acid formed by demethylation of methionine, is involved in numerous processes of methyl group transfer, all playing pivotal roles in the biochemistry of the human body. Increased levels of plasma homocysteine (hyperhomocysteinemia) - which may result from a deficiency of folate, vitamin B6 or B12 or mutations in enzymes regulating the catabolism of homocysteine - are associated with a wide range of clinical manifestations, mostly affecting the central nervous system (e.g., mental retardation, cerebral atrophy and epileptic seizures). Recent evidence suggests that changes in the metabolic fate of homocysteine, leading to hyperhomocysteinemia, may also play a role in the pathophysiology of neurodegenerative disorders, particularly Parkinson's disease (PD). The nervous system might be particularly sensitive to homocysteine, due to the excitotoxic-like properties of the amino acid. However, experimental findings have shown that homocysteine does not seem to posses direct, cytotoxic activity, while the amino acid has proven able to synergize with more specific neurotoxic insults. Hyperhomocysteinemia has been repeatedly reported in PD patients; the increase, however, seems mostly related to the methylated catabolism of l-Dopa, the main pharmacological treatment of PD. Therefore, hyperhomocysteinemia may not be specific to movement disorders or other neurological diseases, the condition being, in fact, rather the result of the combinations of different factors, mainly metabolic, but also genetic and pharmacological, intervening in the neurodegenerative process.

Elevated plasma total homocysteine in centenarians

Homocysteine (Hcy) is a sulfur-containing metabolite of methionine and is an emerging independent risk factor for atherosclerosis. Previous studies have shown that age, gender, renal function and folic acid intake are the main factors influencing total plasma Hcy levels in humans. A unique approach to the science of human longevity is the natural model of centenarians. The objective of this study was to verify whether the previously determined risk factors for atherosclerosis and atherosclerosis-related diseases change with age and, finally, to establish the vitamin nutritional status role. We studied 54 centenarians (14 males and 40 females) aged between 100-107 years (mean age 102.6+/-1.8 years) living in Sicily (Italy), recruited via the Registry Office, and compared them with three control groups composed of subjects with different age ranges. Total plasma Hcy, folate, vitamin B12 and pyridoxal phosphate (PLP) levels were compared between the groups by the Student's t test. The comparison between centenarians and <65-year old, randomly selected individuals showed that in centenarians the mean value of serum creatinine levels was 18 micromol/l (p=0.000) higher, the mean total Hcy value was 22 micromol/l higher (p=0.000), the mean PLP value was 17.9 nmol/l lower (p=0.000), the mean folate level was 2.1 nmol/l lower (p<0.001) and vitamin B12 was 70.5 pmol/l lower (p=0.000). The comparison between centenarians and >65-year old, randomly selected individuals showed that in centenarians the mean value of serum creatinine levels was 8 micromol/l higher (p=0.037), the mean total Hcy value was 11.6 micromol/l higher (p=0.000) and the mean PLP value was 4.2 nmol/l higher (p=0.000). It seems that centenarians are protected by some mechanism (maybe genetic) that allows them a long survival despite the high value of homocysteinemia. On the other hand, it can by hypothesized that good vitamin intake is essential to live over 100 years.

The High Atherosclerotic Risk Among Epileptics: the Atheroprotective Role of Multivitamins

Neurologists have little concern about the high atherosclerotic risk among epileptics. Recent evidences mount that chronic epilepsy and prolonged use of antiepileptic drugs (AEDs) are associated with multiple risk factors that are critically implicated in pathobiology and dysfunction of the vessel wall through complex molecular mechanisms that promote atherogenesis. This review is concerned with three metabolic alterations, which are attributed as major risk factors for atherosclerosis among epileptics: altered metabolism of a) homocysteine (Hcy), b) lipids and lipoproteins, and c) uric acid. Most conventional AEDs reduce folic acid levels, thereby raising Hcy levels. Hyperhomosysteinemia is recently believed to induce endothelial dysfunction and promote atherosclerosis through complex oxidative and excitatory neurotoxic molecular mechanisms. However, Hcy itself is a convulsing substance with increased seizure recurrence and intractability to antiepileptic medications. AEDs can disturb lipid metabolism with resultant hypercholestrolemia and dyslipidemia, common recognized risks for atherosclerosis. Altered uric acid metabolism is common among epileptics. Uric acid has been implicated in endothelial cell damage and decreased endothelial nitric oxide bioavailability. In the presence of atherosclerotic milieu, uric acid interacts with other substrate toxicities and increased reactive oxygen species, accelerating atherosclerosis. The above information forms the rationale for future routine screening and correction of such metabolic alterations in epileptics. A convincing argument now develops that routine polyvitamin supplementation (folic acid, vitamin B12, vitamin B6, vitamin C, vitamin E, and beta-carotene) becomes increasingly important for women and men receiving AEDs at all ages. The atheroprotective effect of multivitamins is through their antioxidant and anti-inflammatory effects together with their lipid and Hcy lowering effects.

Altered platelet reactivity in peripheral vascular disease complicated with elevated plasma homocysteine levels

Elevated plasma concentrations of the sulphur-containing amino acid homocysteine (Hcy) is associated with increased risk of atherosclerosis and arterial thrombosis. The mechanism by which Hcy exerts these effects has yet to be fully elucidated, although a variety of possible mechanisms have been proposed, including endothelial dysfunction or haemostatic abnormalities. However, the influence of Hcy on platelets, cells central to the atherothrombotic process, has never been addressed directly in patient studies. Here, the influence of mild hyperhomocysteinaemia (hHcy) on platelet function was explored in patients with peripheral occlusive arterial disease as evidence by intermittent claudication. Claudicants (n = 39) were assigned to one of two subgroups depending on their plasma Hcy concentrations. hHcy claudicants had plasma Hcy concentrations of 18.9 +/- 1.0 microM (n = 24), compared to 11.3 +/- 0.5 microM for normohomocysteinemic (nHcy) claudicants (n = 15) and 12.6 +/- 0.7 microM for age-matched controls (n=15). Platelet function was evaluated ex vivo in both groups and compared to age-matched controls. Platelet activation and sensitivity to nitric oxide-mediated inhibition was assessed by platelet fibrinogen binding and P-selectin expression. At low concentrations of adenosine diphosphate (ADP; 0.1 microM) and thrombin (0.02 U/ml), platelets from hHcy claudicants were more reactive than those from age-matched controls, but not nHcy claudicants. Agonist-induced P-selectin expression was significantly raised in hHcy claudicants compared to all other groups. Interestingly no differences were observed between nHcy claudicants and age-matched controls, indicating that claudication per se did not affect platelet function. Since platelet activity in vivo is determined by the exposure to both agonists and antagonists, we subsequently tested the sensitivity of platelets to inhibition by nitric oxide (NO), using the same platelet markers. Platelets from hHcy claudicants were significantly less sensitive to GSNO (1-100 microM)-mediated inhibition than all other groups. GSNO (1microM) induced 42.6 +/- 10 and 39 +/- 11.5% inhibition of ADP-induced fibrinogen binding for the nHcy claudicants and age-matched controls, respectively. However, in hHcy claudicants only 16.4 +/- 9.7% inhibition was observed, significantly less than the other groups (P < 0.01). Again no differences between nHCy claudicants and controls were observed. These results suggest the presence of claudication alone does not influence platelet function but if complicated with mild hyperhomocysteinemia, the sensitivity to agonists is increased, and more importantly, their sensitivity to inhibition is greatly reduced. The overall effect would be an increased propensity for platelet activation. The presence of even mildly elevated plasma Hcy could dramatically increase thrombotic risk.

NTPDase and 5'-nucleotidase activities in synaptosomes of hippocampus and serum of rats subjected to homocysteine administration

Patients with homocystinuria, an inborn error of metabolism, present neurological dysfunction and commonly experience frequent thromboembolic complications. The nucleoside triphosphate diphosphohydrolase (NTPDase) and 5'-nucleotidase enzymes regulate the nucleotide/nucleoside ratio in the central nervous system and in the circulation and are thought to be involved in these events. Thus, the current study investigated the effect of homocysteine administration on NTPDase and 5'-nucleotidase activities, in the synaptosomal fraction of rat hippocampus, and on nucleotidase activities in rat serum. Twenty-nine-day-old Wistar rats were divided in two groups: group I (control), animals received 0.9% saline; group II (homocysteine-treated), animals received one single subcutaneous injection of homocysteine (0.6 micromol/g). Rats were killed 1 h after the injection. NTPDase and 5'-nucleotidase activities from brain and serum were significantly increased in the homocysteine-treated group. Results show that, in hippocampus, ATP and ADP hydrolysis increased by 20.5% and 20%, respectively, and AMP hydrolysis increased by 48%, when compared to controls. In serum, ATP and ADP hydrolysis increased 136% and 107%, respectively, and AMP hydrolysis increased 95%, in comparison to controls. The current data strongly indicate that in vivo homocysteine administration alters the activities of the enzymes involved in nucleotide hydrolysis, both in the central nervous system and in the serum of adult rats.

The sigma receptor ligand (+)-pentazocine prevents apoptotic retinal ganglion cell death induced in vitro by homocysteine and glutamate

Recent studies demonstrated that the excitotoxic amino acid homocysteine induces apoptotic death of retinal ganglion cells in vivo. In the present study, an in vitro rat retinal ganglion cell (RGC-5), culture system was used to analyze the toxicity of acute exposure to high levels of homocysteine, the mechanism of homocysteine-induced toxicity, and the usefulness of type 1 sigma receptor (sigmaR1) ligands as neuroprotectants. When cultured RGC-5 cells were subjected to treatment with 1 mM D,L-homocysteine, a significant increase in cell death was detected by terminal dUTP nick end labeling (TUNEL) analysis and analysis of activated caspase. When cells were treated with homocysteine- or glutamate in the presence of MK-801, an antagonist of the N-methyl-D-aspartate (NMDA) receptor, the cell death was inhibited significantly. In contrast, NBQX, an antagonist of the AMPA/Kainate receptor, and nifedipine, a calcium channel blocker, did not prevent the homocysteine- or glutamate-induced cell death. Semiquantitative RT-PCR and immunocytochemical analysis demonstrated that RGC-5 cells were exposed to homocysteine or glutamate express type 1 sigma receptor at levels similar to control cells. Treatment of RGC-5 cells with 3 or 10 microM concentrations of the sigmaR1-specific ligand (+)-pentazocine inhibited significantly the apoptotic cell death induced by homocysteine or glutamate. The results suggest that homocysteine is toxic to ganglion cells in vitro, that the toxicity is mediated via NMDA receptor activation, and that the sigmaR1-specific ligand (+)-pentazocine can block the RGC-5 cell death induced by homocysteine and glutamate.

In vivo and in vitro effects of homocysteine on Na+,K+‐ATPase activity in parietal, prefrontal and cingulate cortex of young rats

In the present study we determined the effect of chronic administration of homocysteine on Na+,K+-ATPase activity in synaptic membranes from parietal, prefrontal and cingulate cortex of young rats. We also studied the in vitro effect of homocysteine on this enzyme activity and on some oxidative stress parameters, namely thiobarbituric acid-reactive substances (TBA-RS) and total radical-trapping antioxidant potential (TRAP) in the same cerebral structures. For the in vivo studies, we induced elevated levels of homocysteine in blood (500 microM), comparable to those of human homocystinuria, and in brain (60 nmol/g wet tissue) of young rats by injecting subcutaneously homocysteine (0.3-0.6 micromol/g of body weight) twice a day at 8 h intervals from the 6th to the 28th postpartum day. Controls received saline in the same volumes. Rats were killed 12 h after the last injection. Chronic administration of homocysteine significantly decreased (50%) Na+,K+-ATPase activity in parietal, increased (36%) in prefrontal and did not alter in cingulate cortex of young rats. In vitro homocysteine decreased Na+,K+-ATPase activity and TRAP and increased TBA-RS in all cerebral structures studied. It is proposed that the alteration of Na+,K+-ATPase and induction of oxidative stress by homocysteine in cerebral cortex may be one of the mechanisms related to the neuronal dysfunction observed in human homocystinuria.

Abdominal aortic aneurysm and its correlation to plasma homocysteine, and vitamins

BACKGROUND

Hyperhomocysteinemia is a recognised independent risk factor in the genesis of atherosclerotic diseases. However, very little is known about the relationship between homocysteine and abdominal aortic aneurysm (AAA). Vitamins, namely B12 and folic acid have been implicated in the regulation of plasma homocysteine levels. However, there has been no prospective study that has analysed the relationship of AAA and plasma homocysteine in light of serum vitamin levels.

AIMS

To study the relationship between plasma homocysteine, serum B12 and folic acid levels, and AAA.

METHOD

Case control study including 38 AAA patients and 36 controls. Fasting homocysteine, B12 and folic acid were determined in serum separated within 1 h of blood collection using a fluorescence polarisation immunoassay technique (FPIA).

RESULTS

Twenty-six (68%) of the AAA patients had elevated levels of homocysteine compared to 2 (6%) in the case control group. The mean homocysteine level in the AAA group was 19.4 micromol/L (SE +/- 1.1) (95% CI 17.17-21.65) and in the control group was 10.9 micromol/L (SE +/- 1) (95% CI 9.95-11.88) (p<0.001). Mean vitamin B12 levels in the AAA and the controls was 332.11 pg/L (SE +/- 16.44) and 414.33 pg/L (SE +/- 19.72), respectively (p<0.004). Mean folic acid in the AAA was 8.02 (SE +/- 0.71) and the control was 9.8 etagm/L (SE +/- 0.69), (ns).

CONCLUSION

This study confirms significantly higher levels of plasma homocysteine in AAA patients but lower levels of B12. Use of supplemental vitamins that should lower plasma homocysteine may modify vascular disease progression. Clinical trials in this direction are warranted.

Brain energy metabolism is compromised by the metabolites accumulating in homocystinuria

Homocystinuria is an inborn error of metabolism caused by severe deficiency of cystathionine beta-synthase activity. It is biochemically characterized by tissue accumulation of homocysteine (Hcy) and methionine (Met). Homocystinuric patients present a variable degree of neurological dysfunction whose pathophysiology is poorly understood. In the present study, we investigated the in vitro effect of Hcy and Met on some parameters of energy metabolism in hippocampus of rats. CO(2) production from [U-14C] acetate, glucose uptake and lactate release were assessed by incubating hippocampus prisms from 28-day-old rats in Krebs-Ringer bicarbonate buffer, pH 7.4, in the absence (controls) or presence of Hcy (10-500 microM) or Met (0.2-2.0mM). Hcy and Met decreased CO(2) production in a dose-dependent manner and increased lactate release. In contrast, glucose uptake was not altered by the metabolites. The effect of Hcy and Met on cytochrome c oxidase activity was also studied. It was observed that Met did not alter this enzyme activity, in contrast with Hcy, which significantly inhibited cytochrome c oxidase activity. It is suggested that impairment of brain energy metabolism caused by the metabolites accumulating in homocystinuria may be related to the neurological symptoms present in homocystinuric patients.

Homocysteine inhibits butyrylcholinesterase activity in rat serum

In the present work we investigated the in vitro effects of homocysteine (Hcy) and methionine (Met), metabolites accumulated in homocystinuria, on butyrylcholinesterase (BuChE) activity in rat serum. We also studied the kinetics of the inhibition of BuChE activity caused by Hcy. For determination of BuChE we used serum of 60-day-old Wistar rats, which was incubated in the absence (control) or presence of Hcy (0.01-0.5 mM) or Met (0.2-2.0 mM). The kinetics of the interaction of Hcy and BuChE was determined using the Lineweaver-Burk double reciprocal plot. Results showed that serum BuChE activity was not altered by Met, but it was significantly inhibited (37%) by 500 microM Hcy, a concentration similar to those found in blood of homocystinuric patients. The apparent Km values, in the absence and presence of 500 microM of Hcy, were 0.034 and 0.142 mM, respectively, and V(max) of BuChE for acetylcholine (ACh) as substrate was 1.25 micromol ACSCh/h/mg of protein. The Ki value obtained was 120 microM, and the inhibition was of the competitive type, suggesting a common binding site for Hcy and ACh. It is proposed that inhibition of cholinesterase activity may be one of the mechanisms involved in the neurological dysfunction observed in homocystinuria.

In vitro effect of homocysteine on some parameters of oxidative stress in rat hippocampus

Homocystinuria is an inherited metabolic disease characterized biochemically by increased blood and brain levels of homocysteine caused by severe deficiency of cystathionine beta-synthase activity. Affected patients present mental retardation, seizures, and atherosclerosis. Oxidative stress plays an important role in the pathogenesis of many neurodegenerative and vascular diseases, such Alzheimer's disease, stroke, and atherosclerosis. However, the mechanisms underlying the neurological damage characteristic of homocystinuria are still poorly understood. To evaluate the involvement of oxidative stress on the neurological dysfunction present in homocystinuria, we measured thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, and total radical-trapping antioxidant potential (TRAP) and antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) in rat hippocampus in the absence (controls) or in the presence of homocysteine (10-500 microM) in vitro. We demonstrated that homocysteine significantly increases TBARS and decreases TRAP, both in a dose-dependent manner, but did not change antioxidant enzymes. Our results suggest that oxidative stress is involved in the neurological dysfunction of homocystinuria. However, further studies are necessary to confirm and extend our findings to the human condition and also to determine whether antioxidant therapy may be of benefit to these patients.

Impairment of energy metabolism in hippocampus of rats subjected to chemically-induced hyperhomocysteinemia

Homocystinuria is an inherited metabolic disease biochemically characterized by tissue accumulation of homocysteine (Hcy). Mental retardation, ischemia and other neurological features, whose mechanisms are still obscure are common symptoms in homocystinuric patients. In this work, we investigated the effect of Hcy administration in Wistar rats on some parameters of energy metabolism in the hippocampus, a cerebral structure directly involved with cognition. The parameters utilized were 14CO2 production, glucose uptake, lactate release and the activities of succinate dehydrogenase and cytochrome c oxidase (COX). Chronic hyperhomocysteinemia was induced by subcutaneous administration of Hcy twice a day from the 6th to the 28th day of life in doses previously determined in our laboratory. Control rats received saline in the same volumes. Rats were killed 12 h after the last injection. Results showed that Hcy administration significantly diminished 14CO2 production and glucose uptake, as well as succinate dehydrogenase and COX activities. It is suggested that impairment of brain energy metabolism may be related to the neurological symptoms present in homocystinuric patients.

Vitamin B12 decreases, but does not normalize, homocysteine and methylmalonic acid in end-stage renal disease: a link with glycine metabolism and possible explanation of hyperhomocysteinemia in end-stage renal disease

The genetic and environmental factors influencing catabolism of homocysteine in end-stage renal disease (ESRD) patients remain poorly understood. This study investigated how genetic and nutritional influences affect the response to high-dose vitamin B(12) and folate treatment in ESRD patients with hyperhomocysteinemia. We studied 81 hemodialysis patients with hyperhomocysteinemia (> 16 micromol/L) on varied doses of a multivitamin containing 1 mg of folic acid per day. After screening blood work, all patients were switched to daily multivitamin therapy including 1 mg of folic acid for 4 weeks. Vitamin B(12), 1 mg/d, was added for an additional 4 weeks. Patients were then randomized to receive folic acid or placebo. The influence of the 3 methylenetetrahydrofolate reductase (MTHFR) 677 C-->T genotypes on the efficacy of vitamin therapy was assessed. In addition, we investigated how the metabolic complications of ESRD, including the relationship between methylmalonic acid (MMA) and circulating glycine, may contribute to hyperhomocysteinemia. There was no significant difference in total homocysteine (tHcy) levels between the MTHFR 677 C-->T genotypes during the screening phase of the trial. Treatment with a daily multivitamin containing 1 mg folate significantly lowered tHcy levels in all patients by 19.2%. Further supplementation with 1 mg vitamin B(12) resulted in greater tHcy reduction among subjects with the MTHFR 677 T/T genotype (P<.01, T/T v C/C or C/T) while lowering MMA equally in all MTHFR genotypes. There was a significant positive correlation between plasma glycine levels and MMA (P <.05). High-dose vitamin therapy significantly lowers, but does not normalize, MMA and tHcy levels. The MTHFR genotype, while influencing homocysteine levels, was not responsible for the majority of the elevation in plasma tHcy.

Reduction of Na(+),K(+)-ATPase activity in hippocampus of rats subjected to chemically induced hyperhomocysteinemia

Hyperhomocysteinemia occurs in homocystinuria, an inherited metabolic disease clinically characterized by thromboembolic episodes and a variable degree of neurological dysfunction whose pathophysiology is poorly known. In this study, we induced elevated levels of homocysteine (Hcy) in blood (500 microM), comparable to those of human homocystinuria, and in brain (60 nmol/g wet tissue) of young rats by injecting subcutaneously homocysteine (0.3-0.6 micromol/g of body weight) twice a day at 8-hr intervals from the 6th to the 28th postpartum day. Controls received saline in the same volumes. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were determined in the hippocampus of treated Hcy- and saline-treated rats. Chronic administration of Hcy significantly decreased (40%) Na(+),K(+)-ATPase activity but did not alter Mg(2+)-ATPase activity. Considering that Na(+),K(+)-ATPase plays a crucial role in the central nervous system, our results suggest that the brain dysfunction found in homocystinuria may be related to the reduction of brain Na(+),K(+)-ATPase activity.

Effect of enoxaparin on homocysteine concentration in warfarin-treated patients

BACKGROUND

Elevated plasma total homocysteine (tHcy) concentration is an emerging independent risk factor for hypercoagulability states and cardiovascular diseases. Many disease states and various drug treatment regimens are known to affect plasma tHcy concentration.

OBJECTIVE

To examine the effect of short-term treatment with the low-molecular-weight heparin enoxaparin on plasma tHcy concentrations.

METHODS

A prospective study was conducted in an outpatient anticoagulation clinic set in a tertiary care referral medical center. Subjects included twenty-four consecutive patients treated with warfarin who were scheduled for short-term enoxaparin treatment. Fasting plasma tHcy concentrations were measured before and after 3 days of enoxaparin treatment in patients who began short-term therapy with enoxaparin because of temporary inadequate anticoagulation (international normalized ratio <1.5). The main outcome measures were the difference in tHcy concentration between baseline and after enoxaparin treatment.

RESULTS

tHcy plasma concentrations decreased in most patients (n = 21), did not change in 2, and increased in 1 patient after 3 days of enoxaparin treatment. The decline of tHcy was statistically significant: from 9.8 +/- 3.4 to 7.6 +/- 2.6 micro mol/L (mean +/- SD; p < 0.005). This decline was more prominent in patients with baseline tHcy plasma concentrations above the normal range compared with patients with normal baseline concentrations. Six patients in whom a third sample was obtained 15-30 days after the last enoxaparin injection developed decreased mean tHcy plasma concentrations: from 9.1 +/- 3.0 micro mol/L at baseline to 6.4 +/- 2.0 micro mol/L on day 3 and further to 5.7 +/- 1.8 micro mol/L on days 15-30. No relation was found between age, gender, treatment indication, and average weekly dose of warfarin to the presence or magnitude of tHcy plasma concentration decline.

CONCLUSIONS

Short-term treatment with enoxaparin reduces plasma tHcy concentrations. Further studies are needed to clarify the mechanism and the clinical significance of enoxaparin's effect.

Plasma total homocysteine levels and the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene: a study in an Italian population with dementia

Hyperhomocysteinemia is a known risk factor for vascular disease and commonly occurs in the elderly. Several studies have shown an association between elevated plasma homocysteine levels and cognitive impairment, indicating that it may play a role in the pathophysiology of dementia. We studied plasma homocysteine, folate, vitamin B12 levels and the MTHFR C677T genotype in an Italian population of patients with dementia. We confirmed that elevated plasma tHcy (>14 micromol/l) is common in elderly subjects with dementia. Although we found a high prevalence of the MTHFR TT genotype (21.2%) the allele frequency is not over-represented relative to the control population. We also observed a high incidence of folate deficiency (38%) in subjects with dementia. Elevated homocysteine was associated with low plasma folate (<5.7 nmol/l) and the MTHFR TT genotype. Moderate to severe hyperhomocysteinemia (>26.1 nmol/l) was associated with a significantly lower MMSE score. Hyperhomocysteinemia may be neurotoxic by several different mechanisms affecting cognitive function. Further studies are needed to fully explore the potential of B vitamin supplementation to lower plasma homocysteine and improve cognitive function.