Homocysteine--a novel risk factor for vascular disease

DNA Methylation in Cancer: Epigenetic View of Dietary and Lifestyle Factors

Background

Alterations in DNA methylation play an important role in cancer development and progression. Dietary nutrients and lifestyle behaviors can influence DNA methylation patterns and thereby modulate cancer risk.

Introduction

To comprehensively review available evidence on how dietary and lifestyle factors impact DNA methylation and contribute to carcinogenesis through epigenetic mechanisms.

Materials and methods

A literature search was conducted using PubMed to identify relevant studies published between 2005 and 2022 that examined relationships between dietary/lifestyle factors and DNA methylation in cancer. Studies investigating the effects of dietary components (eg, micronutrients, phytochemicals), physical activity, smoking, and obesity on global and gene-specific DNA methylation changes in animal and human cancer models were included. Data on specific dietary/lifestyle exposures, cancer types, DNA methylation targets and underlying mechanisms were extracted.

Results

Multiple dietary and lifestyle factors were found to influence DNA methylation patterns through effects on DNA methyltransferase activity, methyl donor availability, and generation of oxidative stress. Altered methylation of specific genes regulating cell proliferation, apoptosis, and inflammation were linked to cancer development and progression.

Conclusion

Dietary and lifestyle interventions aimed at modulating DNA methylation have potential for both cancer prevention and treatment through epigenetic mechanisms. Further research is needed to identify actionable targets for nutrition and lifestyle-based epigenetic therapies.

Impairment of endothelial function in Parkinson's disease

OBJECTIVE

There are conflicting data regarding the relationship between Parkinson's disease (PD) and the atherosclerotic process. This study aimed to compare endothelial function in patients with PD and matched controls. In PD subjects, we searched for factors contributing to endothelial dysfunction as well. Traditional vascular risk factors, PD characteristics, and PD medication were considered.

RESULTS

We prospectively enrolled 41 patients with PD and 41 controls matched for age, sex, body mass index, and vascular risk factors. Endothelial function (EF) was assessed using peripheral arterial tonometry (EndoPAT 2000 device) and expressed as reperfusion hyperemia index (RHI). Clinical characteristics including PD medication were recorded. RHI was non-significantly lower in the PD group than in controls (1.8 ± 0.5 vs. 1.9 ± 0.5, p = 0.478). In PD patients, in linear regression analysis, smoking (beta = -0.453, p = 0.008) and use of dopamine agonists (beta = -0.365, p = 0.030) were significant contributors in a model predicting RHI. Despite non-significant differences in endothelial dysfunction between PD patients and controls, our results suggest an association between smoking, dopamine agonists, and impaired EF in PD patients. The small sample size, as well as the absence of an extended search for traditional and non-traditional vascular risk factors, are the most important factors limiting the interpretation of the current results.

Co3O4 Nanoparticles Uniformly Dispersed in Rational Porous Carbon Nano-Boxes for Significantly Enhanced Electrocatalytic Detection of H2O2 Released from Living Cells

A facile and ingenious method to chemical etching-coordinating a metal-organic framework (MOF) followed by an annealing treatment was proposed to prepare Co₃O₄ nanoparticles uniformly dispersed in rational porous carbon nano-boxes (Co₃O₄@CNBs), which was further used to detect H₂O₂ released from living cells. The Co₃O₄@CNBs H₂O₂ sensor delivers much higher sensitivity than non-etching/coordinating Co₃O₄, offering a limit of detection of 2.32 nM. The wide working range covers 10 nM-359 μM H₂O₂, while possessing good selectivity and excellent reproducibility. Moreover, this biosensor was used to successfully real-time detect H₂O₂ released from living cells, including both healthy and tumor cells. The excellent performance holds great promise for Co₃O₄@CNBs’s applications in electrochemical biomimetic sensing, particularly real-time monitor H₂O₂ released from living cells.

Carotid intima-media thickness is not associated with homocysteine and vitamin D levels in obstructive sleep apnea

Obstructive sleep apnea syndrome (OSA) is associated with increased vascular morbidity. Accelerated atherosclerosis might be one of the most important mechanisms linking OSA with the development of vascular disorders. Homocysteine (HCY) and vitamin D has been associated with atherogenesis. The aim of this study was to assess a possible association between the levels of HCY and vitamin D and the carotid intima-media thickness (cIMT), which is a known marker for subclinical atherosclerosis in patients with OSA. We prospectively enrolled 110 patients with the history of snoring, who underwent standard overnight polysomnography. Clinical characteristics of the population were recorded on admission and blood samples were obtained in the fasting condition following morning. Extracranial cIMT measurements were performed according to the standardized scanning protocol. A significant correlation was found between cIMT and apnea-hypopnea index (r = .276, p = .006), age (r = .486, p < .001), diabetes mellitus (r = .377, p < .001), coronary artery disease (r = .274, p = .006) and history of stroke (r = .251, p = .012). We failed to find any significant correlation between cIMT and the levels of HCY (r = .036, p = .724) or vitamin D (r = .027, p = .800). In conclusion, our data suggest that the association of cIMT with the severity of OSA can be influenced by multiple metabolic consequences of OSA including traditional and non-traditional risk factors. HCY and vitamin D do not seem to play a superior role in this process.

Differential expression of lipid peroxidation and total antioxidant status in Indian patients with cardiovascular and cerebrovascular disease

Data from studies examining lipid peroxidation as a mechanism involved with hyperhomocysteinemia (HHcy)-induced vascular remodeling in patients with occlusive vascular disease have been contradictory. It has not yet been studied in Indians within the context of atherogenesis. Therefore, we measured the levels of homocysteine (Hcy), malondialdehyde (MDA) as a measure of lipid peroxides (LPOs), and total antioxidant status (TAS) in the serum of 167 patients with occlusive vascular disease [coronary artery disease (CAD) = 43; cerebrovascular disease (CVD) = 82; peripheral vascular disease (PVD) = 42]. Each of these groups was further divided into groups of individuals with or without HHcy. In the case of CAD and CVD, patients with HHcy had significantly higher LPOs than those without HHcy (p = 0.009, 0.001, respectively). TAS was significantly lower in CVD patients with HHcy than in those without (p = 0.014). In patients with CAD or CVD, Hcy directly correlated with LPOs (p = 0.002, 0.001, respectively). Lipid peroxidation is a significant mechanism in HHcy-induced vascular remodeling in CAD and CVD, but not in PVD, probably because it is not relevant in thrombosis (38 of 42 patients of PVD had deep-vein thrombosis). To explain the significantly lower TAS in CVD, we hypothesized that CVD patients present very early with grave symptoms, whereas CAD and PVD occur over a longer period of time. Therefore, when CVD presents, TAS is still overwhelmed by HHcy-induced oxidative stress. Hence, adjuvant therapy with antioxidants would benefit patients with CVD.

Frequency of citrus fruit intake is associated with the incidence of cardiovascular disease: the Jichi Medical School cohort study

Background

It has been reported that fruit intake protects against cardiovascular disease (CVD). However, most of the relevant studies were conducted in Western countries, and only a few investigated Japanese populations. The present cohort study assessed the effect of citrus fruit intake on the incidence of CVD and its subtypes in a Japanese population.

Methods

A baseline examination consisting of physical and blood examinations and a self-administered questionnaire was conducted during the period from April 1992 through July 1995. Dietary habits were assessed using a food frequency questionnaire that was divided into 5 categories. Citrus fruit was examined separately due to its frequent consumption by the general Japanese population. Using the Cox proportional hazards model, data from 10 623 participants (4147 men, 6476 women) who had no history of CVD or carcinoma were analyzed to assess the association between frequency of citrus fruit intake and CVD incidence.

Results

Frequent intake of citrus fruit was associated with a lower incidence of CVD: the hazard ratio for almost daily intake versus infrequent intake of citrus fruit was 0.57 (95% confidence interval: 0.33–1.01, P for trend = 0.04) in men and 0.51 (0.29–0.88, P for trend = 0.02) in women. Frequent intake of citrus fruit was also associated with lower incidences of both all stroke and cerebral infarction, but not hemorrhagic stroke or myocardial infarction.

Conclusions

Frequent intake of citrus fruit may reduce the incidence of CVD, especially cerebral infarction, in men and women.

Dietary intake and status of folate and vitamin B12 and their association with homocysteine and cardiovascular disease in European populations

BACKGROUND/OBJECTIVES

Folate and vitamin B12 have been suggested to play a role in chronic diseases like cardiovascular diseases. The objectives are to give an overview of the actual intake and status of folate and vitamin B12 in general populations in Europe, and to evaluate these in view of the current vitamin recommendations and the homocysteine concentration.

METHODS

Searches in Medline with 'folic acid', 'folate' and 'vitamin B12', 'B12' or 'cobalamin' as key words were combined with the names of the European countries. Populations between 18 and 65 years were included.

RESULTS

Sixty-three articles reporting on studies from 15 European countries were selected. Low folate intakes were observed in Norway, Sweden, Denmark and the Netherlands. Low intakes of vitamin B12 were not common and only seen in one small Greek study. In the countries with a low intake of folate, the recommended levels were generally not achieved, which was also reflected in the folate status. Vitamin B12 intake was not strongly associated with the vitamin B12 status, which can explain why in the Netherlands and Germany the vitamin B12 status was inadequate, despite sufficient intake levels. In countries with a low folate intake in particular, the Hcy concentration was higher than ideal.

CONCLUSIONS

Populations from the Nordic countries, the Netherlands, Germany and Greece may need to improve their intakes of folic acid, B12 or both to either meet the recommendations or to optimize their statuses. This could be achieved via a food-based approach, food fortification or supplements.

Endothelial function markers in parkinsonian patients with hyperhomocysteinemia

Hyperhomocysteinemia is considered a risk factor for vascular disease causing endothelial damage and consequently atherogenesis. The purpose of this study was to investigate the effect of elevated homocysteine on certain biochemical markers of endothelial function in patients with idiopathic Parkinson's disease (PD). Blood homocysteine levels were assessed in 57 PD patients and 40 matched normal controls. Investigation of the C677T 5,10 methylenetetrahydrofolate reductase (MTHFR) genotype was also performed in 43 PD patients. The following markers of endothelial function were assessed: superoxide dismutase (SOD), nitric oxide (NO), sICAM-1 and sE-selectin. Homocysteine levels were found mildly elevated in PD patients particularly in those treated with L-Dopa. MTHFR genotype did not influence significantly this finding. SOD activity was found reduced but it was not correlated to homocysteine levels. All other parameters measured were normal and were not related to hyperhomocysteinemia. Our findings indicate that mild hyperhomocysteinemia in PD patients was not associated with endothelial dysfunction.

Inactivation of S-adenosylhomocysteine hydrolase with haloethyl and dihalocyclopropyl esters derived from homoadenosine-6′-carboxylic acid

In a search for new inhibitors that exploit 5'-6' 'hydrolytic activity' of AdoHcy hydrolase, a new series of haloethyl and dihalocyclopropyl esters 2-3 were designed and their interaction with the enzyme studied. Incubation of the enzyme with 2-3 resulted in time- and concentration-dependent inactivation of AdoHcy hydrolase as well as almost total depletion of its NAD(+) content. Further results indicated that the 'oxidative' but not the 'hydrolytic' activity was involved in the inactivation process.

Inactivation of human S-adenosylhomocysteine hydrolase by covalent labeling of cysteine 195 with thionucleoside derivatives

A new series of 5'-thioadenosine derivatives 1-4 were synthesized for selectively targeting (195)Cys of human AdoHcy hydrolase. Their incubation with the enzyme resulted in time- and concentration-dependent inactivation, without major modifications of the NAD(+)/NADH ratio. The electrospray mass analysis of the inactivated enzyme with 1, 2, 3, and 4b showed that inhibition was accompanied by the formation of a specific and covalent labeling of each AdoHcy hydrolase subunit. Proteolytic cleavage (endo-Lys-C) and subsequent peptide characterization of the labeled enzyme revealed that (195)Cys was the residue modified during the inactivation process.

Homocysteine-induced enhancement of spontaneous contractions of myometrium isolated from pregnant women

BACKGROUND

Although many associations have been demonstrated between hyperhomocysteinemia and pregnancy complications, such as spontaneous abortion, preterm labor, preeclampsia and low birthweight, it is still not clear whether hyperhomocysteinemia is the cause or the consequence of these pregnancy complications. The aim of this study was to investigate the effects of homocysteine on the spontaneous contractility of isolated pregnant human myometrium.

METHODS

Myometrium samples obtained from women undergoing elective caesarean section were suspended in a jacketed organ bath containing Krebs' solution at 37 degrees C (pH 7.4), continuously gassed with 95% O2 and 5% CO2. After manifestation of spontaneous contractions under 2 g of resting tension, homocysteine was applied to the organ bath, and amplitude and frequency of contractions were evaluated at 20-min intervals. Statistical analysis of amplitude and frequency of the contractions was performed using the Kruskal-Wallis analysis of variance test.

RESULTS

Application of 0.1 mm homocysteine had no significant effect on either frequency (4.63 +/- 0.42 vs. 4.01 +/- 0.53 for the control period; p > 0.05) or amplitude (3.20 +/- 0.07 g vs. 3.15 +/- 0.07 g; p > 0.05) of spontaneous contractions, while 1 and 2 mm homocysteine significantly increased the frequency (8.54 +/- 0.62 vs. 3.9 +/- 0.44, p < 0.02, and 12.32 +/- 0.72 vs. 3.96 +/- 0.51, p < 0.001, respectively) of spontaneous contractions but caused only a modest change in amplitude (2.92 +/- 0.04 g vs. 2.87 +/- 0.05 g, p > 0.05, and 3.02 +/- 0.06 g vs. 2.93 +/- 0.05 g, p > 0.05, respectively).

CONCLUSION

Results from this study indicate for the first time that homocysteine causes enhancement of spontaneous contractions of myometrium derived from pregnant women.

Serum homocysteine levels are increased in women with gestational diabetes mellitus

Serum homocysteine (sHcy) has been found to be elevated in patients with type 2 diabetes mellitus, as well as in other clinical conditions associated with insulin resistance and/or vascular diseases. The aims of this study were to measure the relationship between sHcy with biohumoral markers of insulin resistance in pregnant women affected with gestational diabetes mellitus (GDM). We studied 2 groups of pregnant women categorized, after a 100-g, 3-hour oral glucose tolerance test (OGTT) as nondiabetic (n = 78) or affected with GDM (n = 15), by measuring sHcy, serum folate, albumin, vitamin B(12), uric acid, and lipids. In both groups, peripheral insulin sensitivity was measured by using the OGTT-derived index of Matsuda and DeFronzo (ISI(OGTT)). Serum homocysteine was significantly higher in the group with GDM compared with nondiabetic women (5.88 +/- 2.26 micromol/L v 4.45 +/- 1.52 micromol/L; P =.003); was inversely related to serum folate (r = -.48; P =.0001), and was significantly related to serum albumin (r =.27; P =.009), 2-hour plasma glucose (r =.25; P =.01), as well as to serum uric acid (r =.23; P =.03). No relationship was observed between sHcy and serum vitamin B(12), serum triglycerides, total, or high-density lipoprotein (HDL) cholesterol, mean blood pressure and ISI(OGTT). Vitamin B(12) was correlated with ISI(OGTT) (r =.36; P =.0005) and inversely with mean blood pressure (r = -.24; P =.02). GDM remained significantly associated with higher sHcy concentrations also after adjusting for age, serum folate, albumin, uric acid, ISI(OGTT), and vitamin B(12) (P =.006). In conclusion, we found that sHcy is significantly increased in women with GDM, independently of other confounding variables, is significantly related to 2-hour OGTT plasma glucose, and seems unrelated to insulin resistance in these subjects.

Sustained increases of plasma homocysteine, copper, and serum ceruloplasmin after coronary artery bypass grafting

BACKGROUND

Homocysteine (Hcy) is an independent risk factor for coronary artery disease, but there are no reports on Hcy levels in patients undergoing coronary artery bypass graft (CABG) surgery. Interactions between Hcy and copper may mediate the vasculopathic impact of Hcy, and this may play a role in vein graft failure. The aim of this study was to assess the perioperative levels of Hcy, copper, ceruloplasmin (CP), folate, and vitamin B12 in patients undergoing myocardial revascularization surgery.

METHODS

Blood samples were taken from 55 consecutive patients undergoing elective conventional CABG (43 male; mean age, 63.2 +/- 5.2 years) 1 day preoperatively and postoperatively at 1 day, 6 days, and 6 weeks. Hcy, copper, CP, red cell folate, vitamin B12, creatinine, and C-reactive protein (CRP) were then measured using standard clinical chemistry methods. The same protocol was applied to 10 patients (7 male; mean age, 63.3 +/- 5.2 years) undergoing off-pump coronary artery bypass (OPCAB) surgery.

RESULTS

In the conventional CABG group, there were significant increases in the plasma concentrations at 6 days and 6 weeks postoperatively of Hcy (from 10.1 to 11.6 and 13.5 micromol/L, respectively), plasma copper (from 13.5 to 20.3 and 18.5 micromol/L), and serum ceruloplasmin (from 0.3 to 0.41 and 0.44 g/L). CRP and vitamin B12 were elevated at 6 days but not 6 weeks after the operation. In contrast, red cell folate and creatinine were not significantly changed. The subgroup analysis for the OPCAB patients showed the same trend as for the conventional group.

CONCLUSIONS

Coronary surgery precipitates a significant and sustained increase in the blood concentrations of Hcy and copper, which is not due to a decrease in folate and vitamin B12, altered renal function, or inflammation. Further studies are required to establish whether the concomitant increase in Hcy and copper plays an etiological role in vein graft disease.