Folate and vitamin B12 deficiency and hyperhomocysteinemia promote oxidative stress in adult type 2 diabetes

Nutraceuticals and Diet-based Phytochemicals in Type 2 Diabetes Mellitus: From Whole Food to Components with Defined Roles and Mechanisms

BACKGROUND

Over the past decades, the development and use of an array of prescription medications have considerably improved the clinical management of type 2 diabetes mellitus and the quality of life of patients. However, as our knowledge of the associated risk factors and approaches to its management increases, the increasing roles of diet and the composition of the diet in the etiology and successful management of diabetes mellitus are being illuminated. Presently, a lot of attention is being given to nutraceuticals and certain phytochemicals that are integral parts of the human diet. It is believed that a clearer understanding of their roles may be crucial to 'non-invasive' or minimallyintrusive management, with regards to daily living of patients. In this review, an overview of nutraceutical components and phytochemicals that may be of benefit, or had been known to be beneficial in diabetes mellitus is given. Also, how the roles of such dietary components are evolving in the management of this disorder is highlighted. Lastly, the obstacles that need to be overcome before nutraceuticals can be considered as options for the clinical management of diabetes mellitus areconsidered.

CONCLUSION

Despite studies that demonstrate their efficacy, no nutraceutical or food-derived compound has been formally adopted as a direct replacement for any class of antidiabetic drugs.

Chronic folate deficiency induces glucose and lipid metabolism disorders and subsequent cognitive dysfunction in mice

Previous studies have shown that folate levels were decreased in patients with type 2 diabetes (T2D) and further lowered in T2D patients with cognitive impairment. However, whether folate deficiency could cause T2D and subsequent cognitive dysfunction is still unknown. The present study aimed to explore the effects of chronic folate deficiency (CFD) on glucose and lipid metabolism and cognitive function in mice. Seven-week-old mice were fed with either a CFD or control diet for 25 weeks. Serum folate was significantly reduced, whereas serum total homocysteine was significantly increased in the CFD group. Moreover, CFD induced obesity after a 6-week diet treatment, glucose intolerance and insulin resistance after a 16-week-diet treatment. In addition, CFD reduced the hepatic p-Akt/Akt ratio in response to acute insulin administration. Moreover, CFD increased serum triglyceride levels, upregulated hepatic Acc1 and Fasn mRNA expression, and downregulated hepatic Cd36 and ApoB mRNA expression. After a 24-week diet treatment, CFD induced anxiety-related activities and impairment of spatial learning and memory performance. This study demonstrates that folate deficiency could induce obesity, glucose and lipid metabolism disorders and subsequent cognitive dysfunction.

The effects of folate supplementation on lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

Although several studies have assessed the effect of folate supplementation on lipid profiles among patients with metabolic diseases, findings are inconsistent. This review of randomized controlled trials (RCTs) was conducted to summarize the evidence on the effects of folate supplementation on lipid profiles among patients with metabolic diseases.

METHODS

Randomized-controlled trials (RCTs) published in PubMed, EMBASE, Web of Science and Cochrane Library databases up to until 20 August 2017 were searched. Two review authors independently assessed study eligibility, extracted data, and evaluated risk of bias of included studies. Heterogeneity was measured with a Q-test and with I₂ statistics. Data were pooled by using the fix or random-effect model based on the heterogeneity test results and expressed as standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

A total of thirteen randomized controlled trials were included. Folate supplementation did not affect systolic blood pressure (SMD -0.87; 95% CI, -1.83, 0.09) and diastolic blood pressure (SMD -0.59; 95% CI, -1.55, 0.37), and lipid profiles including triglycerides (SMD 0.10; 95% CI, -0.42, 0.63), total- (SMD 0.06; 95% CI, -0.31, 0.43), HDL- (SMD 0.04; 95% CI, -0.36, 0.44), VLDL- (SMD 0.08; 95% CI, -0.24, 0.41), and LDL-cholesterol (SMD -0.14; 95% CI, -0.55, 0.28).

CONCLUSIONS

Folate supplementation did not affect blood pressures and lipid profiles among patients with metabolic diseases. Additional prospective studies regarding the impact of folate supplementation on blood pressures and lipid profiles in patients with metabolic diseases are necessary.

Gene-diet-related factors of hyperglycaemia in postmenopausal women

As ageing and increased body fat are the signs of insulin resistance, we have studied whether the presence of Pro12Ala and C1431T of peroxisome proliferator-activated receptor gamma 2 gene and Trp64Arg of beta 3-adrenergic receptor gene may predispose to the hyperglycaemia development in postmenopausal women, who have never undergone hypoglycaemic treatment. The distributions of selected allele and genotype frequencies were determined by the PCR–RFLP method in normo- and hyperglycaemic, who have never been diagnosed and treated for diabetes mellitus were measured. The amount of body fat and lean body mass (LBM) were assessed by the bioimpedance method and nutritional habits by 7-day dietary recall. There were no differences between the distribution of genotypes and the allele frequencies of the Pro12Ala, C1431T and Trp64Arg polymorphisms in normo- and hyperglycaemic women. Hyperglycaemic women were characterized by visceral obesity, hypertension, higher serum insulin and triglycerides, higher intake of fat and lower consumption of complex carbohydrates and B vitamins. Normoglycaemic women with Pro12Pro polymorphism acquired higher energy from dietary fat (p < 0.0276) and lower energy from carbohydrates (p < 0.0480) than normoglycaemic Ala12 carriers. Subjects with Pro12Pro polymorphism and LBM > 58% of total body mass or with Trp64Trp and normal triglycerides have higher chance of normoglycaemia. Genotyping for Pro12Ala and Trp64Arg polymorphism in postmenopausal women may have the clinical benefit of predicting hyperglycaemia, thereby contributing to the prevention of diabetes mellitus development in the future. However, not only the genetic background but also the dietary habits (intake of fat, carbohydrates and B vitamins) determine the risk of hyperglycaemia.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Serum Antioxidant Parameters are Significantly Increased in Patients with Type 2 Diabetes Mellitus after Consumption of Chinese Propolis: A Randomized Controlled Trial Based on Fasting Serum Glucose Level

INTRODUCTION

Propolis is a natural product with many biological activities. The present study was designed to evaluate the effects of Chinese propolis on glucose metabolism, antioxidant function, and inflammatory cytokines in patients with type 2 diabetes mellitus (T2DM).

METHODS

In the 18-week study, recruited T2DM patients were randomly divided into a Chinese propolis group (900 mg/day) (n = 31) and a control group (n = 30) according to fasting serum glucose levels at baseline.

RESULTS

At the end of the study, no significant difference was found between the groups in serum glucose, glycosylated hemoglobin, insulin, aldose reductase, or adiponectin. However, serum GSH, flavonoids, and polyphenols were significantly increased, and serum lactate dehydrogenase activity was significantly reduced in the Chinese propolis group. Meanwhile, serum IL-6 was significantly increased in the Chinese propolis group.

CONCLUSION

Chinese propolis is effective at improving antioxidant function in T2DM patients, partly by increasing serum antioxidant parameters.

Hyperhomocysteinemia as a Metabolic Risk Factor for Glucose Intolerance Among High-Risk Groups of Chinese Adults

BACKGROUND Impaired glucose tolerance (IGT) is characterized by insulin resistance and causes atherosclerosis. Hyperhomocysteinemia is associated with insulin resistance and predicts cardiovascular diseases. In this study, we assessed the possible association between homocysteine and IGT. MATERIAL AND METHODS This was a cross-sectional study of 118 consecutive subjects with IGT (IGT group) and 128 consecutive subjects with normal glucose tolerance (NGT group). Homocysteine and clinical characteristics were measured. RESULTS The IGT group had higher homocysteine than the NGT group [18.00 (14.00, 22.25) vs. 12.50 (9.00, 15.00) μmol/L, p<0.001]. Homocysteine was positively associated with body mass index (BMI) (r=0.178, p=0.005), triglycerides (r=0.306, p<0.001), fasting blood glucose (FBG) (r=0.312, p<0.001), 2-hour postchallenge glucose (2hPG) (r=0.363, p<0.001), fasting insulin (FINS) (r=0.655, p<0.001), and homeostasis model assessment for insulin resistance (HOMA-IR) (r=0.643, p<0.001), and was negatively correlated with high-density lipoprotein cholesterol (HDL-C) (r=-0.250, p<0.001). After controlling for confounders, hyperinsulinemia (β=7.430, p<0.001) was independently related to hyperhomocysteinemia. In a logistic regression analysis, high triglycerides (OR=1.177, p<0.001) and homocysteine (OR=1.508, p=0.007), and low HDL-C (OR=0.315, p=0.026) were associated with IGT. CONCLUSIONS Patients with IGT have higher homocysteine levels compared with subjects with normal glucose tolerance, and hyperhomocysteinemia might be correlated with IGT.

Antioxidant Properties of Probiotic Bacteria

Oxidative stress defines a condition in which the prooxidant-antioxidant balance in the cell is disturbed, resulting in DNA hydroxylation, protein denaturation, lipid peroxidation, and apoptosis, ultimately compromising cells' viability. Probiotics have been known for many beneficial health effects, and the consumption of probiotics alone or in food shows that strain-specific probiotics can present antioxidant activity and reduce damages caused by oxidation. However, the oxidation-resistant ability of probiotics, especially the underling mechanisms, is not properly understood. In this view, there is interest to figure out the antioxidant property of probiotics and summarize the mode of action of probiotic bacteria in antioxidation. Therefore, in the present paper, the antioxidant mechanisms of probiotics have been reviewed in terms of their ability to improve the antioxidant system and their ability to decrease radical generation. Since in recent years, oxidative stress has been associated with an altered gut microbiota, the effects of probiotics on intestinal flora composition are also elaborated.

Vitamin B12 deficiency evaluation and treatment in severe dry eye disease with neuropathic ocular pain

PURPOSE

This study aims to understand the effect of vitamin B12 deficiency on neuropathic ocular pain (NOP) and symptoms in patients with dry eye disease (DED).

METHODS

Patients with severe DED (without receiving topical artificial tears treatment) and ocular pain were enrolled (n = 90). Patients with severe DED and vitamin B12 deficiency (group 1, n = 45) received parenteral vitamin B12 supplement + topical treatment (artificial tears treatment + cyclosporine), and patients with severe DED and normal serum vitamin B12 level (group 2, n = 45) received only topical treatment (artificial tears treatment + cyclosporine). Patients were evaluated by the ocular surface disease index (OSDI) questionnaire, 3rd question (have you experienced painful or sore eyes during last week?) score of OSDI as a pain determiner and pain frequency measure), tear break up time (TBUT), and Schirmer's type 1 test. We compared the groups' OSDI, TBUT, and Schirmer's test recordings at the first visit and after 12 weeks retrospectively.

RESULTS

The OSDI score, 3rd OSDI question score, TBUT, and Schirmer's test results improved after 12 weeks (p < 0.001 for each group). The mean vitamin B12 level at enrollment was 144.24 ±43.36 pg/ml in group 1 and 417.53 ±87.22 pg/ml in group 2. The mean vitamin B12 level in group 1 reached to 450 ±60.563 pg/ml after 12 weeks of treatment. The mean score changes between the groups were not statistically significant; however, the decrease in the OSDI questionnaire score (-30.80 ±5.24) and 3rd OSDI question score (-2.82 ±0.53) were remarkable in group 1 (Table 2). The mean TBUT increase was +7.98 ±2.90 s and Schirmer's test result increase was +12.16 ±2.01 mm in group 1. The mean TBUT increase was +6.18 ±1.49 s and Schirmer's test result increase was +6.71 ±1.47 mm in group 2.

CONCLUSIONS

These findings indicate that vitamin B12 deficiency is related with NOP. It may be important to consider measuring the serum vitamin B12 level in patients with severe DED presenting with resistant ocular pain despite taking topical treatment.

Histological study on the protective role of vitamin B complex on the cerebellum of diabetic rat

BACKGROUND

Disorder in cerebellar structure was reported in diabetes mellitus. B vitamins are involved in many significant metabolic processes within the brain.

AIM OF THE WORK

To detect the protective role of vitamin B complex on the histological structure of the cerebellum of experimentally induced diabetic rat.

MATERIAL & METHODS

Eighteen adult male Wistar rats were divided into two groups. Group I: normal vehicle control (n=6). Group II: streptozotocin-induced diabetic rats (n=12), which was equally divided into two subgroups; IIA (diabetic vehicle control), IIB (diabetic vitamin B complex-treated): streptozotocin-induced diabetic rats treated with vitamin B complex (1mg/kg/day) for 6 weeks. Specimens from the cerebellum were processed for light and electron microscopy.

RESULTS

In vitamin B complex treated group, the histological changes in Purkinje cells, astrocytes and oligodendrocytes were improved compared with the diabetic non-treated group. The white matter revealed intact myelinated axons. Inducible nitric oxide synthase (iNOS) and caspase-3 expression reduced. Glial fibrillary acidic protein (GFAP) expression revealed less activated astroglia. The number of Purkinje cells/mm(2) significantly increased. While, the number of GFAP positive astrocytes/mm(2) significantly decreased. In addition, the blood glucose level was reduced.

CONCLUSION

Vitamin B complex protected the cerebellum from the histological changes which occurred in STZ- induced diabetic rats.

Associations between Vitamin B-12 Status and Oxidative Stress and Inflammation in Diabetic Vegetarians and Omnivores

Diabetes is considered an oxidative stress and a chronic inflammatory disease. The purpose of this study was to investigate the correlations between vitamin B-12 status and oxidative stress and inflammation in diabetic vegetarians and omnivores. We enrolled 154 patients with type 2 diabetes (54 vegetarians and 100 omnivores). Levels of fasting glucose, glycohemoglobin (HbA1c), lipid profiles, oxidative stress, antioxidant enzymes activity, and inflammatory makers were measured. Diabetic vegetarians with higher levels of vitamin B-12 (>250 pmol/L) had significantly lower levels of fasting glucose, HbA1c and higher antioxidant enzyme activity (catalase) than those with lower levels of vitamin B-12 (≤250 pmol/L). A significant association was found between vitamin B-12 status and fasting glucose (r = −0.17, p = 0.03), HbA1c (r = −0.33, p = 0.02), oxidative stress (oxidized low density lipoprotein-cholesterol, r = −0.19, p = 0.03), and antioxidant enzyme activity (catalase, r = 0.28, p = 0.01) in the diabetic vegetarians; vitamin B-12 status was significantly correlated with inflammatory markers (interleukin-6, r = −0.33, p < 0.01) in diabetic omnivores. As a result, we suggest that it is necessary to monitor the levels of vitamin B-12 in patients with diabetes, particularly those adhering to a vegetarian diet.

Determination and characterization of total thiols in mouse serum samples using hydrophilic interaction liquid chromatography with fluorescence detection and mass spectrometry

Biothiols such as homocysteine, cysteine, and glutathione play many biologically important roles, especially in reduction-oxidation homeostasis and resistance to oxidative stress, and the measurement of their concentrations in model animal fluids is important in clarifying the pathology of thiol-related diseases. In this study, an analytical method for total biothiols in mouse serum using hydrophilic interaction liquid chromatography (HILIC) with fluorescence detection was developed. Mouse serum samples were derivatized with ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F), after reduction by tris(2-carboxyethyl)phosphine. Five biothiols (homocysteine, cysteine, cysteinylglycine, glutathione, and γ-glutamylcysteine) in the mouse sera were separated within 16 min on an amide-type HILIC column. The method possessed good linearity, good reproducibility with an intra-day variance of less than 3%, and low detection limits of 0.2-4 nM. Concentrations of homocysteine, cysteine, cysteinylglycine, glutathione, and γ-glutamylcysteine in the mouse serum samples were calculated as 6.7 ± 0.3, 227.7 ± 16.9, 1.2 ± 0.4, 77.5 ± 29.2, and 8.2 ± 0.9 μM, respectively (mean ± S.D., n = 4). Furthermore, HILIC-negative electrospray ionization-mass spectrometry (MS) analysis using a high-resolution mass spectrometer was conducted to determine the exact masses of two unknown peaks, which were found in the mouse serum samples with high signal intensity and were not detected in human plasma samples. The exact masses of the unknown compounds were determined as 1184.519 and 800.281 (as SBD-derivatized negative ions), which possessed a product ion common to SBD-thiols (m/z 230.954, as [SBD-SH](-)) upon tandem MS spectrometric analysis.

Vitamins and type 2 diabetes mellitus

The present review evaluates the relationship between type 2 diabetes mellitus and individual or combined vitamins. Antioxidant vitamins A, C and E are found decreased in diabetic subjects, possibly due to an increased need to control the excessive oxidative stress produced by abnormalities in glucose metabolism. On the other hand, retinol binding protein exerts a modulating effect, as it has adipokine functions. With respect to the B group vitamins, thiamin, pyridoxine and biotin have been found decreased but the mechanisms are not clear, however supplementation has shown some improvement of the metabolic control in diabetic patients. The absorption of folic acid and vitamin B12 is importantly decreased by the prolongued use of metformin, which is the first choice drug in uncomplicated diabetes, thus these two nutrients have been found deficient in the disease and most probably need to be supplemented regularly. On the other hand, vitamin D is considered a risk factor for the development of diabetes as well as its complications, particularly cardiovascular ones. Although some studies have found an association of vitamin K intake with glucose metabolism further research is needed. Studies on the use of multivitamin supplements have shown unconclusive results. After reviewing the evidence, no real recommendation on the use of vitamin supplements in type 2 diabetes mellitus can be issued, however patients using metformin during prolongued periods may need folic acid and vitamin B12.

Should we be more cautious about replacement of vitamin B12 in patients with cancer receiving cytotoxic chemotherapy?

Vitamin B12 (Cbl) deficiency may cause hematologic and neurologic dysfunction. Replacement therapy is effective in correcting hematologic abnormalities and improving neurologic symptoms. Cbl is known to have antioxidant activity. This antioxidant activity may antagonize the effects of chemotherapeutics (i.e. genotoxic effects of paclitaxel) on tumor DNA. We claim that Cbl replacement should be done more cautiously in patients receiving cytotoxic chemotherapy.

Plasma levels of homocysteine and cysteine increased in pediatric NAFLD and strongly correlated with severity of liver damage

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of metabolic abnormalities ranging from simple triglyceride accumulation in the hepatocytes to hepatic steatosis with inflammation, ballooning and fibrosis. It has been demonstrated that the pathogenesis of NAFLD involves increased oxidative stress, with consumption of the major cellular antioxidant, glutathione (GSH). Liver has a fundamental role in sulfur compound metabolism, although the data reported on plasma thiols status in NAFLD are conflicting. We recruited 63 NAFLD patients, and we analyzed all plasma thiols, such as homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CysGly) and GSH, by high-performance liquid chromatography (HPLC) with fluorescence detection. Hcy, Cys and CysGly plasma levels increased in NAFLD patients (p < 0.0001); whereas GSH levels were decreased in NAFLD patients when compared to controls (p < 0.0001). On the contrary, patients with steatohepatitis exhibited lower levels of Hcy and Cys than subjects without. Furthermore, a positive correlation was found between Hcy and Cys and the presence of fibrosis in children with NAFLD. Taken together, these data demonstrated a defective hepatic sulfur metabolism in children with NAFLD, and that high levels of Hcy and Cys probably correlates with a pattern of more severe histological liver damage, due to mechanisms that require further studies.

Evaluation of oxidative stress levels in the conjunctival epithelium of patients with or without dry eye, and dry eye patients treated with preservative-free hyaluronic acid 0.15 % and vitamin B12 eye drops

PURPOSE

Increased levels of oxidative stress have been seen in animal models of dry eye and in the conjunctival epithelial cells of patients with Sjögren's syndrome. The aims of this study were to compare the levels of oxidative stress in patients with dry eye and patients without dry eye and to evaluate the effects of treatment with preservative-free eye drops containing hyaluronic acid 0.15 % and vitamin B12 on oxidative stress and dry eye symptoms.

METHODS

Three cohorts of patients who were to undergo planned cataract surgery were enrolled: patients with dry eye randomized to either no treatment (n = 29) or treatment (n = 32) with hyaluronic acid/vitamin B12 eye drops, and patients without dry eye (n = 42). Patients were assessed by Schirmer's type I test, fluorescein clearance test (FCT), Break Up Time (BUT), and Ocular Surface Disease Index (OSDI). Lipid peroxidation, a marker of oxidative stress, was assessed by LP-CHOLOX test.

RESULTS

Compared with patients without dry eye, patients with dry eye had significantly increased levels of oxidative stress, higher OSDI and FCT scores, and significantly lower Schirmer's test and BUT scores. Treatment with eye drops containing hyaluronic acid 0.15 % and vitamin B12 was associated with significantly reduced levels of oxidative stress and OSDI and FCT scores and significantly increased Schirmer's test and BUT scores.

CONCLUSIONS

These findings indicate that oxidative stress is associated with dry eye and that hyaluronic acid/vitamin B12 eye drops may attenuate oxidative stress and inflammation, improving dry eye symptoms. Further study in controlled clinical trials is warranted.

Interaction of chromium(III) with a N,N'-disubstituted hydroxylamine-(diamido) ligand: a combined experimental and theoretical study

Reaction of hydroxylamine hydrochloride with prop-2-enamide in dichloromethane in the presence of triethylamine resulted in the isolation of the N,N'-disubstituted hydroxylamine-(diamido) ligand, 3,3'-(hydroxyazanediyl)dipropanamide (Hhydia). The ligand Hhydia was characterized by multinuclear NMR, high-resolution electrospray ionization mass spectrometry (ESI-MS), and X-ray structure analysis. Interaction of Hhydia with trans-[Cr(III)Cl2(H2O)4]Cl·2H2O in ethanol yields the ionization isomers [Cr(III)(Hhydia)2]Cl3·2H2O(1·2H2O) and cis/trans-[Cr(III)Cl2(Hhydia)2]Cl·2H2O (2·2H2O). The X-ray structure analysis of 1 revealed that the chromium atom in [Cr(III)(Hhydia)2](3+) is bonded to two neutral tridentate O,N,O-Hhydia ligands. The twist angle, θ, in [Cr(III)(Hhydia)2](3+) is 54.5(6)(0), that is, very close to an ideal octahedron. The intramolecular hydrogen bonds developed between the N-OH group of the first ligand and the amidic oxygen atom of the second ligand and vice versa contribute to the overall stability of the cation [Cr(III)(Hhydia)2](3+). The reaction rate constant of the formation of Cr(III) complexes 1·2H2O and 2·2H2O was found to be 8.7(±0.8) × 10(-5) M(-1) s(-1) at 25 °C in methyl alcohol and follows a first-order law kinetics based on the biologically relevant ligand Hhydia. The reaction rate constant is considerably faster in comparison with the corresponding water exchange rate constant for the hydrated chromium(III). The modification of the kinetics is of fundamental importance for the chromium(III) chemistry in biological systems. Ultraviolet-visible and electron paramagnetic resonance studies, both in solution and in the solid state, ESI-MS, and conductivity measurements support the fact that, irrespective of the solvent used in the interaction of Hhydia with trans-[Cr(III)Cl2(H2O)4]Cl·2H2O, the ionization isomers[Cr(III)(Hhydia)2]Cl3·2H2O (1·2H2O) and cis/trans-[Cr(III)Cl2(Hhydia)2]Cl·2H2O (2·2H2O) are produced.The reaction medium affects only the relevant percentage of the isomers in the solid state. The thermodynamic stability of the ionization isomers 1·2H2O and cis/trans-2·2H2O, their molecular structures as well as the vibrational spectra and the energetics of the Cr(III)- Hhydia/hydia(-) were studied by means of density functional theory calculations and found to be in excellent agreement with our experimental observations.

DNA modifications: function and applications in normal and disease States

Epigenetics refers to a variety of processes that have heritable effects on gene expression programs without changes in DNA sequence. Key players in epigenetic control are chemical modifications to DNA, histone, and non-histone chromosomal proteins, which establish a complex regulatory network that controls genome function. Methylation of DNA at the fifth position of cytosine in CpG dinucleotides (5-methylcytosine, 5mC), which is carried out by DNA methyltransferases, is commonly associated with gene silencing. However, high resolution mapping of DNA methylation has revealed that 5mC is enriched in exonic nucleosomes and at intron-exon junctions, suggesting a role of DNA methylation in the relationship between elongation and RNA splicing. Recent studies have increased our knowledge of another modification of DNA, 5-hydroxymethylcytosine (5hmC), which is a product of the ten-eleven translocation (TET) proteins converting 5mC to 5hmC. In this review, we will highlight current studies on the role of 5mC and 5hmC in regulating gene expression (using some aspects of brain development as examples). Further the roles of these modifications in detection of pathological states (type 2 diabetes, Rett syndrome, fetal alcohol spectrum disorders and teratogen exposure) will be discussed.

The role of antioxidants and other agents in alleviating hyperglycemia mediated oxidative stress and injury in liver

Several antioxidants and agents having similar antioxidant effects are known to exert beneficial effects in ameliorating the injurious effects of hyperglycemia on liver in different diabetic in vitro and in vivo models. The review deals with some of the agents which have been shown to exert protective effects on liver against hyperglycemic insult and the various mechanisms involved. The different classes of agents which protect the diabetic liver or decrease the severity of hyperglycemia mediated injury include flavonoids, catechins, and other polyphenolic compounds, curcumin and its derivatives, certain vitamins, hormones and drugs, trace elements, prototypical antioxidants and amino acids. Some of the pronounced changes mediated by the antioxidants in liver exposed to hyperglycemia include decreased oxidative stress, and alterations in carbohydrate and lipid metabolism. Other mechanisms through which the agents ameliorate hyperglycemia mediated liver injury include decrease in oxidative DNA and protein damage, restoration of mitochondrial structural and functional integrity, decrease in inflammation and improved insulin signaling. Thus, antioxidants may prove to be an important mode of defense in maintaining normal hepatic functions in diabetes.

Analytical methods involving separation techniques for determination of low-molecular-weight biothiols in human plasma and blood

Low-molecular-weight biothiols such as homocysteine, cysteine, and glutathione are metabolites of the sulfur cycle and play important roles in biological processes such as the antioxidant defense network, methionine cycle, and protein synthesis. Thiol concentrations in human plasma and blood are related to diseases such as cardiovascular disease, neurodegenerative disease, and cancer. The concentrations of homocysteine, cysteine, and glutathione in plasma samples from healthy human subjects are approximately in the range of 5-15, 200-300, and 1-5 μM, respectively. Glutathione concentration in the whole blood is in the millimolar range. Measurement of biothiol levels in plasma and blood is thought to be important for understanding the physiological roles and biomarkers for certain diseases. This review summarizes the relationship of biothiols with certain disease as well as pre-analytical treatment and analytical methods for determination of biothiols in human plasma and blood by using high-performance liquid chromatography and capillary electrophoresis coupled with ultraviolet, fluorescence, or chemiluminescence detection; or mass spectrometry.

Folate deficiency triggers an oxidative-nitrosative stress-mediated apoptotic cell death and impedes insulin biosynthesis in RINm5F pancreatic islet β-cells: relevant to the pathogenesis of diabetes

It has been postulated that folic acid (folate) deficiency (FD) may be a risk factor for the pathogenesis of a variety of oxidative stress-triggered chronic degenerative diseases including diabetes, however, the direct evidence to lend support to this hypothesis is scanty. For this reason, we set out to study if FD can trigger the apoptotic events in an insulin-producing pancreatic RINm5F islet β cells. When these cells were cultivated under FD condition, a time-dependent growth impediment was observed and the demise of these cells was demonstrated to be apoptotic in nature proceeding through a mitochondria-dependent pathway. In addition to evoke oxidative stress, FD condition could also trigger nitrosative stress through a NF-κB-dependent iNOS-mediated overproduction of nitric oxide (NO). The latter compound could then trigger depletion of endoplasmic reticulum (ER) calcium (Ca²⁺) store leading to cytosolic Ca²⁺ overload and caused ER stress as evidence by the activation of CHOP expression. Furthermore, FD-induced apoptosis of RINm5F cells was found to be correlated with a time-dependent depletion of intracellular gluthathione (GSH) and a severe down-regulation of Bcl-2 expression. Along the same vein, we also demonstrated that FD could severely impede RINm5F cells to synthesize insulin and their abilities to secret insulin in response to glucose stimulation were appreciably hampered. Even more importantly, we found that folate replenishment could not restore the ability of RINm5F cells to resynthesize insulin. Taken together, our data provide strong evidence to support the hypothesis that FD is a legitimate risk factor for the pathogenesis of diabetes.

Higher homocysteine and lower betaine increase the risk of microangiopathy in patients with diabetes mellitus carrying the GG genotype of PEMT G774C

BACKGROUND

Diabetes represents one of the greatest medical and socioeconomic threats worldwide. The pathogenesis involved is complicated. The effect of methyl donors and genetic polymorphisms in metabolic enzymes on the risk of microangiopathy in patients with diabetes is not well understood. This study investigates the association of homocysteine, choline and betaine levels and phosphatidylethanolamine N-methyltransferase (PEMT) G774C (rs12325817) genotypes with the risk of diabetes and its related microangiopathic complications.

METHODS

Between January 2009 and June 2010, 184 diabetic patients and 188 non-diabetic control subjects were enrolled in the hospital-based case-control study. Serum concentrations of betaine and choline were determined by high-performance liquid chromatography (HPLC)-mass spectrometry. Serum concentrations of homocysteine were assayed using HPLC. PEMT gene mutations were detected by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

After adjustment for potential confounders, serum total homocysteine had a significant dose-dependent positive association, and serum choline had an inverse association with the risks of diabetes and its microangiopathic complications (both p < 0.001). Although serum betaine was not associated with the risk of diabetes, it had a significant inverse association with diabetic microangiopathy. Compared with GG genotype, the CC genotype of PEMT G774C was associated with a decreased risk of diabetes (OR 0.559, 95% CI 0.338, 0.926) and its microangiopathy (OR 0.452, 95% CI 0.218, 0.937).

CONCLUSION

The GG genotype of the PEMT G774C polymorphism, higher levels of serum homocysteine and lower levels of serum betaine are associated with an increased risk of microangiopathy in patients with diabetes.

Differences in traditional and non-traditional risk factors with special reference to nutritional factors in patients with coronary artery disease with or without diabetes mellitus

INTRODUCTION

There is an increase in awareness about the role of nutritional factors in chronic non-communicable diseases. We therefore conducted this study with an aim to assess the relationship between nutritional factor (vitamin B12 and homocysteine [Hcy]) and its association with insulin resistance and inflammatory markers, and differences in traditional and non-traditional risk factors among diabetics and non-diabetics in known cases of coronary artery disease (CAD).

MATERIALS AND METHODS

Three hundred consecutive patients with known coronary disease on coronary angiography, who were >25 years old were included in this study. All cases were interviewed using a questionnaire. Blood samples were analyzed for insulin, vitamin B12, Hcy and inflammatory markers (highly sensitive C-reactive protein [hsCRP], interleukin-6 [IL-6], Tumor necrosis factor-alfa [TNF-α]). Insulin resistance was calculated with homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

Mean age of the patients was 60.95 ± 12.3 years. Body mass index and waist hip ratio were comparable in both groups. Triglyceride, very low-density lipoprotein and HbA1C were significantly higher and high-density lipoprotein (HDL) was significantly lower in patients with diabetes. Patients with diabetes had significantly high levels of IL-6, hsCRP and TNF-α compared with non-diabetic patients. Insulin resistance was twofold higher in diabetic patients. Serum vitamin B12 levels were significantly lower and Hcy was significantly higher in the diabetic group compared with the non-diabetic patients. HbA1C, HOMA-IR and Hcy levels were positively correlated with inflammatory markers in the total study population and in the non-diabetic patients; but, in diabetic patients, HbA1C and Hcy showed this relation.

CONCLUSIONS

Vitamin B12 deficiency is common in the diabetic population. Hcy levels were higher in diabetics compared with non-diabetics, and were related to glycemic level and insulin resistance in diabetic patients. Patients with diabetes had higher traditional risk factors than patients without diabetes in known patients with CAD. Glycemic status was associated with insulin resistance and inflammatory markers.