Effect of B-group vitamins and antioxidant vitamins on hyperhomocysteinemia:a double-blind, randomized, factorial-design, controlled trial

Mild hyperhomocysteinemia is accepted as a risk factor for premature cardiovascular disease. In a population with a high prevalence of cardiovascular disease, we screened a group of clinically healthy working men aged 30-49 y (n = 509) for plasma homocysteine and 5,10-methylene tetrahydrofolate reductase (MTHFR) genotype status. Those with mildly elevated homocysteine concentrations (> or = 8.34 micromol/L) were selected for intervention. In a randomized, factorial-design, controlled trial we assessed the effects of B-group vitamins and antioxidant vitamin supplementation on homocysteine concentrations. The 132 men were randomly assigned to one of four groups: supplementation with B-group vitamins alone (1 mg folic acid, 7.2 mg pyridoxine, and 0.02 mg cyanocobalamin), antioxidant vitamins alone (150 mg ascorbic acid, 67 mg RRR-alpha-tocopherol, and 9 mg beta-carotene), B-group vitamins with antioxidant vitamins, or placebo. Intervention was double-blind. A total of 101 men completed the 8-wk intervention. When homocysteine concentrations were analyzed by group, significant (P <0.001) decreases (32.0% and 30.0%, respectively) were observed in both groups receiving B-group vitamins either with or without antioxidants. The effect of B-group vitamins alone over 8 wk was a reduction in homocysteine concentrations of 27.9% (95% CI: 22.0%, 33.3%; P <0.001) whereas antioxidants alone produced a nonsignificant increase of 5.1% (95% CI: -2.8%, 13.6%; P = 0.21). There was no evidence of any interaction between the two groups of vitamins. The effect of B-group vitamin supplementation seemed to depend on MTHFR genotype. Supplementation with the B-group vitamins with or without antioxidants reduced homocysteine in the men with mildly elevated concentrations, and hence may be effective in reducing cardiovascular risk.

An integrated transcriptomics and proteomics analysis of the secretome of the helminth pathogen Fasciola hepatica: Proteins associated with invasion and infection of the mammalian host

To infect their mammalian hosts, Fasciola hepatica larvae must penetrate and traverse the intestinal wall of the duodenum, move through the peritoneum, and penetrate the liver. After migrating through and feeding on the liver, causing extensive tissue damage, the parasites move to their final niche in the bile ducts where they mature and produce eggs. Here we integrated a transcriptomics and proteomics approach to profile Fasciola secretory proteins that are involved in host-pathogen interactions and to correlate changes in their expression with the migration of the parasite. Prediction of F. hepatica secretory proteins from 14,031 expressed sequence tags (ESTs) available from the Wellcome Trust Sanger Centre using the semiautomated EST2Secretome pipeline showed that the major components of adult parasite secretions are proteolytic enzymes including cathepsin L, cathepsin B, and asparaginyl endopeptidase cysteine proteases as well as novel trypsin-like serine proteases and carboxypeptidases. Proteomics analysis of proteins secreted by infective larvae, immature flukes, and adult F. hepatica showed that these proteases are developmentally regulated and correlate with the passage of the parasite through host tissues and its encounters with different host macromolecules. Proteases such as FhCL3 and cathepsin B have specific functions in larvae activation and intestinal wall penetration, whereas FhCL1, FhCL2, and FhCL5 are required for liver penetration and tissue and blood feeding. Besides proteases, the parasites secrete an array of antioxidants that are also highly regulated according to their migration through host tissues. However, whereas the proteases of F. hepatica are secreted into the parasite gut via a classical endoplasmic reticulum/Golgi pathway, we speculate that the antioxidants, which all lack a signal sequence, are released via a non-classical trans-tegumental pathway.

Conformational Change of Mitochondrial Complex I Increases ROS Sensitivity During Ischemia

Aims: Myocardial ischemia/reperfusion (I/R) is associated with mitochondrial dysfunction and subsequent cardiomyocyte death. The generation of excessive quantities of reactive oxygen species (ROS) and resultant damage to mitochondrial enzymes is considered an important mechanism underlying reperfusion injury. Mitochondrial complex I can exist in two interconvertible states: active (A) and deactive or dormant (D). We have studied the active/deactive (A/D) equilibrium in several tissues under ischemic conditions in vivo and investigated the sensitivity of both forms of the heart enzyme to ROS.

Results: We found that in the heart, t½ of complex I deactivation during ischemia was 10?min, and that reperfusion resulted in the return of A/D equilibrium to its initial level. The rate of superoxide generation by complex I was higher in ischemic samples where content of the D-form was higher. Only the D-form was susceptible to inhibition by H2O2 or superoxide, whereas turnover-dependent activation of the enzyme resulted in formation of the A-form, which was much less sensitive to ROS. The mitochondrial-encoded subunit ND3, most likely responsible for the sensitivity of the D-form to ROS, was identified by redox difference gel electrophoresis.

Innovation: A combined in vivo and biochemical approach suggests that sensitivity of the mitochondrial system to ROS during myocardial I/R can be significantly affected by the conformational state of complex I, which may therefore represent a new therapeutic target in this setting.

Conclusion: The presented data suggest that transition of complex I into the D-form in the absence of oxygen may represent a key event in promoting cardiac injury during I/R.

Arsenate causes differential acute toxicity to two P-deprived genotypes of rice seedlings (Oryza sativa L.)

Significant genotypic difference in response to arsenate toxicity in rice (Oryza sativa) was investigated in root elongation, arsenate uptake kinetics, physiological and biochemical response and arsenic (As) speciation. Uptake kinetics data showed that P-deprived genotype 94D-54 had a little higher As uptake than P-deprived 94D-64, but the difference was not large enough to cause acute toxicity in P-deprived 94D-54. There was no difference in tissue P concentrations between the two genotypes under P deficient conditions. In addition, arsenic speciation in plant tissues (using high performance liquid chromatography-inductively coupled plasma mass spectrometry) was not different between P pretreatments and between genotypes. P-deprived genotype 94D-54 suffered much higher stress induced by arsenate toxicity than P-deprived genotype 94D-64, in terms of lipid peroxidation, tissue H2O2 concentrations and exosmosis of K, P and As. However, P-deprived 94D-54 also had higher overproduction of enzymatic antioxidants (with higher GPX, SOD, CAT) and NPT (non-protein thiols) than P-deprived 94D-64. It appeared that, the higher sensitivity of P-deprived 94D-54 to arsenate toxicity might cause the overproduction of NPT, thus leading to the depletion of GSH and to the accumulation of H2O2. The differential sensitivity of the two genotypes has major implications for breeding rice for As affected paddy soil.

DNA double strand break repair: a radiation perspective

SIGNIFICANCE:
Ionizing radiation (IR) can induce a wide range of unique deoxyribonucleic acid (DNA) lesions due to the spatiotemporal correlation of the ionization produced. Of these, DNA double strand breaks (DSBs) play a key role. Complex mechanisms and sophisticated pathways are available within cells to restore the integrity and sequence of the damaged DNA molecules.
RECENT ADVANCES:
Here we review the main aspects of the DNA DSB repair mechanisms with emphasis on the molecular pathways, radiation-induced lesions, and their significance for cellular processes.
CRITICAL ISSUES:
Although the main characteristics and proteins involved in the two DNA DSB repair processes present in eukaryotic cells (homologous recombination and nonhomologous end-joining) are reasonably well established, there are still uncertainties regarding the primary sensing event and their dependency on the complexity, location, and time of the damage. Interactions and overlaps between the different pathways play a critical role in defining the repair efficiency and determining the cellular functional behavior due to unrepaired/miss-repaired DNA lesions. The repair pathways involved in repairing lesions induced by soluble factors released from directly irradiated cells may also differ from the established response mechanisms.
FUTURE DIRECTIONS:
An improved understanding of the molecular pathways involved in sensing and repairing damaged DNA molecules and the role of DSBs is crucial for the development of novel classes of drugs to treat human diseases and to exploit characteristics of IR and alterations in tumor cells for successful radiotherapy applications.

Tyrosine nitration of prostacyclin synthase is associated with enhanced retinal cell apoptosis in diabetes

The risk of diabetic retinopathy is associated with the presence of both oxidative stress and toxic eicosanoids. Whether oxidative stress actually causes diabetic retinopathy via the generation of toxic eicosanoids, however, remains unknown. The aim of the present study was to determine whether tyrosine nitration of prostacyclin synthase (PGIS) contributes to retinal cell death in vitro and in vivo. Exposure of human retinal pericytes to heavily oxidized and glycated LDL (HOG-LDL), but not native forms of LDL (N-LDL), for 24 hours significantly increased pericyte apoptosis, accompanied by increased tyrosine nitration of PGIS and decreased PGIS activity. Inhibition of the thromboxane receptor or cyclooxygenase-2 dramatically attenuated HOG-LDL-induced apoptosis without restoring PGIS activity. Administration of superoxide dismutase (to scavenge superoxide anions) or L-N(G)-nitroarginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) restored PGIS activity and attenuated pericyte apoptosis. In Akita mouse retinas, diabetes increased intraretinal levels of oxidized LDL and glycated LDL, induced PGIS nitration, enhanced apoptotic cell death, and impaired blood-retinal barrier function. Chronic administration of tempol, a superoxide scavenger, reduced intraretinal oxidized LDL and glycated LDL levels, PGIS nitration, and retina cell apoptosis, thereby preserving the integrity of blood-retinal barriers. In conclusion, oxidized LDL-mediated PGIS nitration and associated thromboxane receptor stimulation might be important in the initiation and progression of diabetic retinopathy.

Low-energy cranberry juice decreases lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome

Cranberries, high in polyphenols, have been associated with several cardiovascular health benefits, although limited clinical trials have been reported to validate these findings. We tested the hypothesis that commercially available low-energy cranberry juice (Ocean Spray Cranberries, Inc, Lakeville-Middleboro, Mass) will decrease surrogate risk factors of cardiovascular disease, such as lipid oxidation, inflammation, and dyslipidemia, in subjects with metabolic syndrome. In a randomized, double-blind, placebo-controlled trial, participants identified with metabolic syndrome (n = 15-16/group) were assigned to 1 of 2 groups: cranberry juice (480 mL/day) or placebo (480 mL/day) for 8 weeks. Anthropometrics, blood pressure measurements, dietary analyses, and fasting blood draws were conducted at screen and 8 weeks of the study. Cranberry juice significantly increased plasma antioxidant capacity (1.5 ± 0.6 to 2.2 ± 0.4 µmol/L [means ± SD], P <.05) and decreased oxidized low-density lipoprotein and malondialdehyde (120.4 ± 31.0 to 80.4 ± 34.6 U/L and 3.4 ± 1.1 to 1.7 ± 0.7 µmol/L, respectively [means ± SD], P <.05) at 8 weeks vs placebo. However, cranberry juice consumption caused no significant improvements in blood pressure, glucose and lipid profiles, C-reactive protein, and interleukin-6. No changes in these parameters were noted in the placebo group. In conclusion, low-energy cranberry juice (2 cups/day) significantly reduces lipid oxidation and increases plasma antioxidant capacity in women with metabolic syndrome.

Strawberries decrease atherosclerotic markers in subjects with metabolic syndrome

Strawberries have been reported to be potent antioxidants and reduce cardiovascular risk factors, such as elevated blood pressure, hyperglycemia, dyslipidemia, and inflammation in limited studies. We hypothesized that freeze-dried strawberry supplementation will improve blood pressure, impaired glucose, dyslipidemia, or circulating adhesion molecules in obese subjects with metabolic syndrome, thereby lowering cardiovascular risk factors in these subjects. Twenty-seven subjects with metabolic syndrome (2 males and 25 females; body mass index, 37.5 +/- 2.15 kg/m(2); age, 47.0 +/- 3.0 years [means +/- SE]) consumed 4 cups of freeze-dried strawberry beverage (50 g freeze-dried strawberries approximately 3 cups fresh strawberries) or equivalent amounts of fluids (controls, 4 cups of water) daily for 8 weeks in a randomized controlled trial. Anthropometrics and blood pressure measurements, assessment of dietary intakes, and fasting blood draws were conducted at screen and 8 weeks of the study. Strawberry supplementation significantly decreased total and low-density lipoprotein cholesterol (5.8 +/- 0.2 to 5.2 +/- 0.2 mmol/L and 3.5 +/- 0.2 to 3.1 +/- 0.1 mmol/L, respectively [means +/- SE], P <.05) and small low-density lipoprotein particles using nuclear magnetic resonance-determined lipoprotein subclass profile vs controls at 8 weeks (794.6 +/- 94.0 to 681.8 +/- 86.0 nmol/L [means +/- SE], P <.05). Strawberry supplementation further decreased circulating levels of vascular cell adhesion molecule-1 vs controls at 8 weeks (272.7 +/- 17.4 to 223.0 +/- 14.0 ng/mL [means +/- SE], P <.05). Serum glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure, and waist circumference were not affected. Thus, short-term freeze-dried strawberry supplementation improved selected atherosclerotic risk factors, including dyslipidemia and circulating adhesion molecules in subjects with metabolic syndrome, and these results need confirmation in future trials.

Green tea minimally affects biomarkers of inflammation in obese subjects with metabolic syndrome

Green tea (Camellia sinensis) has shown to exert cardioprotective benefits in observational studies. The objective of this clinical trial was to assess the effects of green tea on features of metabolic syndrome and inflammation in obese subjects.

Berries:emerging impact on cardiovascular health

Berries are a good source of polyphenols, especially anthocyanins, micronutrients, and fiber. In epidemiological and clinical studies, these constituents have been associated with improved cardiovascular risk profiles. Human intervention studies using chokeberries, cranberries, blueberries, and strawberries (either fresh, or as juice, or freeze-dried), or purified anthocyanin extracts have demonstrated significant improvements in LDL oxidation, lipid peroxidation, total plasma antioxidant capacity, dyslipidemia, and glucose metabolism. Benefits were seen in healthy subjects and in those with existing metabolic risk factors. Underlying mechanisms for these beneficial effects are believed to include upregulation of endothelial nitric oxide synthase, decreased activities of carbohydrate digestive enzymes, decreased oxidative stress, and inhibition of inflammatory gene expression and foam cell formation. Though limited, these data support the recommendation of berries as an essential fruit group in a heart-healthy diet.

Freeze-dried strawberry powder improves lipid profile and lipid peroxidation in women with metabolic syndrome:baseline and post intervention effects

Strawberry flavonoids are potent antioxidants and anti-inflammatory agents that have been shown to reduce cardiovascular disease risk factors in prospective cohort studies. Effects of strawberry supplementation on metabolic risk factors have not been studied in obese populations. We tested the hypothesis that freeze-dried strawberry powder (FSP) will lower fasting lipids and biomarkers of oxidative stress and inflammation at four weeks compared to baseline. We also tested the tolerability and safety of FSP in subjects with metabolic syndrome. FSP is a concentrated source of polyphenolic flavonoids, fiber and phytosterols.

In vivo glycated low-density lipoprotein is not more susceptible to oxidation than nonglycated low-density lipoprotein in type 1 diabetes

It has been suggested that low-density lipoprotein (LDL) modified by glycation may be more susceptible to oxidation and thus, enhance its atherogenicity. Using affinity chromatography, LDL glycated in vivo (G-LDL) and relatively nonglycated. (N-LDL) subfractions can be isolated from the same individual. The extent of and susceptibility to oxidation of N-LDL compared with G-LDL was determined in 15 type 1 diabetic patients. Total LDL was isolated and separated by boronate affinity chromatography into relatively glycated (G-) and nonglycated (N-) subfractions. The extent of glycation, glycoxidation, and lipoxidation, lipid soluble antioxidant content, susceptibility to in vitro oxidation, and nuclear magnetic resonance (NMR)-determined particle size and subclass distribution were determined for each subfraction. Glycation, (fructose-lysine) was higher in G-LDL versus N-LDL, (0.28 +/- 0.08 v 0.13 +/- 0.04 mmol/mol lysine, P <.0001). However, levels of glycoxidation/lipoxidation products and of antioxidants were similar or lower in G-LDL compared with N-LDL and were inversely correlated with fructose-lysine (FL) concentrations in G-LDL, but positively correlated in N-LDL. In vitro LDL (CuCl2) oxidation demonstrated a longer lag time for oxidation of G-LDL than N-LDL (50 +/- 0.16 v 37 +/- 0.15 min, P <.01), but there was no difference in the rate or extent of lipid oxidation, nor in any aspect of protein oxidation. Mean LDL particle size and subclass distribution did not differ between G-LDL and N-LDL. Thus, G-LDL from well-controlled type 1 diabetic patients is not more modified by oxidation, more susceptible to oxidation, or smaller than relatively N-LDL, suggesting alternative factors may contribute to the atherogenicity of LDL from type 1 diabetic patients.

Glycation, glycoxidation, and cross-linking of collagen by glucose. Kinetics, mechanisms, and inhibition of late stages of the Maillard reaction

The Maillard or browning reaction between sugar and protein contributes to the increased chemical modification and cross-linking of long-lived tissue proteins in diabetes. To evaluate the role of glycation and oxidation in these reactions, we have studied the effects of oxidative and antioxidative conditions and various types of inhibitors on the reaction of glucose with rat tail tendon collagen in phosphate buffer at physiological pH and temperature. The chemical modifications of collagen that were measured included fructoselysine, the glycoxidation products N epsilon-(carboxymethyl)lysine and pentosidine and fluorescence. Collagen cross-linking was evaluated by analysis of cyanogen bromide peptides using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by changes in collagen solubilization on treatment with pepsin or sodium dodecylsulfate. Although glycation was unaffected, formation of glycoxidation products and cross-linking of collagen were inhibited by antioxidative conditions. The kinetics of formation of glycoxidation products proceeded with a short lag phase and were independent of the amount of Amadori adduct on the protein, suggesting that autoxidative degradation of glucose was a major contributor to glycoxidation and cross-linking reactions. Chelators, sulfhydryl compounds, antioxidants, and aminoguanidine also inhibited formation of glycoxidation products, generation of fluorescence, and cross-linking of collagen without significant effect on the extent of glycation of the protein. We conclude that autoxidation of glucose or Amadori compounds on protein plays a major role in the formation of glycoxidation products and cross-liking of collagen by glucose in vitro and that chelators, sulfhydryl compounds, antioxidants, and aminoguanidine act as uncouplers of glycation from subsequent glycoxidation and cross-linking reactions.

Disordered vascular compliance in haemochromatosis

Background: A relationship may exist between body iron stores, endothelial dysfunction and overall cardiovascular risk.

Aims: To compare vascular compliance, biochemical endothelial function and antioxidant status between patients with homozygous hereditary haemochromatosis and healthy controls.

Methods: Haemochromatosis patients and healthy controls were recruited. Measures of vascular compliance were assessed by applanation tonometry. Serological markers of endothelial function (plasma lipid hydroperoxides, cell adhesion molecules), antioxidant levels (ascorbate, lipid soluble antioxidants) and high-sensitivity C-reactive protein (CRP) were also measured.

Results: Thirty-five hereditary haemochromatosis patients (ten females, mean age 54.6) and 36 controls (27 female, mean age 54.0) were recruited. Haemochromatosis patients had significantly higher systolic and diastolic blood pressures. Pulse wave velocity (PWV) was significantly higher in male haemochromatosis patients (9.90 vs. 8.65 m/s, p = 0.048). Following adjustment for age and blood pressure, male haemochromatosis patients continued to have a trend for higher PWVs (+1.37 m/s, p = 0.058). Haemochromatosis patients had significantly lower levels of ascorbate (46.11 vs. 72.68 lmol/L, p = 0.011), retinol (1.17 vs. 1.81 lmol/L, p = 0.001) and g-tocopherol (2.51 vs. 3.14 lmol/L, p = 0.011). However, there was no difference in lipid hydroperoxides (0.46 vs. 0.47 nmol/L, p = 0.94), cell adhesion molecule levels (ICAM: 348.12 vs. 308.03 ng/mL, p = 0.32 and VCAM: 472.78 vs. 461.31 ng/mL, p = 0.79) or high-sensitivity CRP (225.01 vs. 207.13 mg/L, p = 0.32).

Conclusions: Haemochromatosis is associated with higher PWVs in males and diminished antioxidants across the sexes but no evidence of endothelial dysfunction or increased lipid peroxidation.

Oxidative stress and inflammation in lean and obese subjects with polycystic ovary syndrome

To determine whether polycystic ovary syndrome (PCOS) independently influences oxidative stress and inflammation or if the culprit is the comorbidities of obesity and/or insulin resistance common to this condition.