Metallothionein Gene Deficiency Facilitates the Differentiation of C2C12 Myoblasts into Slow-Twitch Myotubes.

Metallothionein (MT) 1 and 2 are ubiquitously expressed cysteine-rich, low molecular weight proteins. MT expression is upregulated in skeletal muscle during aging. MTs also play role in multiple types of skeletal muscle atrophy. Meanwhile, it has been reported that MT1 and MT2 gene deficiency increases myogenesis in MT knockout (MTKO) mice. However, little is known about the effect of MTs on muscle formation and atrophy. In this study, we investigated the effect of MT1 and MT2 gene knock-out using the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (CRISPR-Cas9) system in an in vitro skeletal muscle differentiation model (C2C12 cell line). MT deficiency promoted myogenic differentiation and myotube formation in C2C12 cells. Muscle-specific transcription factors MyoD and myogenin were found to be upregulated at the late stage of myotube differentiation in MTKO cells. Furthermore, the fast-twitch myosin heavy chain (MyHC) protein expression was similar in MTKO and mock-transfected myotubes, but slow-MyHC expression was higher in MTKO cells than in mock cells. The MT gene deletion did not affect the number of fast MyHC-positive myotubes but increased the number of slow MyHC-positive myotubes. Treatment with the antioxidant N-acetylcysteine (NAC) inhibited the increase in the number of slow MyHC-positive myotubes as well as slow-MyHC expression in MTKO cells. In contrast, NAC treatment did not alter the number of fast MyHC-positive myotubes or the expression of fast-MyHC in MTKO cells. These results suggest that the antioxidant effects of MTs may be involved in slow-twitch myofiber formation in skeletal muscle.

Mutation in Smek2 regulating hepatic glucose metabolism causes hypersarcosinemia and hyperhomocysteinemia in rats.

Suppressor of mek1 (Dictyostelium) homolog 2 (Smek2), was identified as one of the responsible genes for diet-induced hypercholesterolemia (DIHC) of exogenously hypercholesterolemic (ExHC) rats. A deletion mutation in Smek2 leads to DIHC via impaired glycolysis in the livers of ExHC rats. The intracellular role of Smek2 remains obscure. We used microarrays to investigate Smek2 functions with ExHC and ExHC.BN-Dihc2BN congenic rats that harbor a non-pathological Smek2 allele from Brown-Norway rats on an ExHC background. Microarray analysis revealed that Smek2 dysfunction leads to extremely low sarcosine dehydrogenase (Sardh) expression in the liver of ExHC rats. Sarcosine dehydrogenase demethylates sarcosine, a byproduct of homocysteine metabolism. The ExHC rats with dysfunctional Sardh developed hypersarcosinemia and homocysteinemia, a risk factor for atherosclerosis, with or without dietary cholesterol. The mRNA expression of Bhmt, a homocysteine metabolic enzyme and the hepatic content of betaine (trimethylglycine), a methyl donor for homocysteine methylation were low in ExHC rats. Results suggest that homocysteine metabolism rendered fragile by a shortage of betaine results in homocysteinemia, and that Smek2 dysfunction causes abnormalities in sarcosine and homocysteine metabolism.

Metabolomic profiling of plasma from middle-aged and advanced-age male mice reveals the metabolic abnormalities of carnitine biosynthesis in metallothionein gene knockout mice.

Metallothionein (MT) is a family of low molecular weight, cysteine-rich proteins that regulate zinc homeostasis and have potential protective effects against oxidative stress and toxic metals. MT1 and MT2 gene knockout (MTKO) mice show shorter lifespans than wild-type (WT) mice. In this study, we aimed to investigate how MT gene deficiency accelerates aging. We performed comparative metabolomic analyses of plasma between MTKO and WT male mice at middle age (50-week-old) and advanced age (100-week-old) using liquid chromatography with time-of-flight mass spectrometry (LC-TOF-MS). The concentration of N6,N6,N6-trimethyl-L-lysine (TML), which is a metabolic intermediate in carnitine biosynthesis, was consistently higher in the plasma of MTKO mice compared to that of WT mice at middle and advanced age. Quantitative reverse transcription PCR (RT-PCR) analysis revealed remarkably lower mRNA levels of Tmlhe, which encodes TML dioxygenase, in the liver and kidney of male MTKO mice compared to that of WT mice. L-carnitine is essential for ß-oxidation of long-chain fatty acids in mitochondria, the activity of which is closely related to aging. Our results suggest that reduced carnitine biosynthesis capacity in MTKO mice compared to WT mice led to metabolic disorders of fatty acids in mitochondria in MTKO mice, which may have caused shortened lifespans.

Alteration of Serum Phospholipid n-6 Polyunsaturated Fatty Acid Compositions in Nonalcoholic Fatty Liver Disease in the Japanese Population: A Cross-Sectional Study.

We performed a cross-sectional study on 215 Japanese employees aged 20-68 years to investigate the association between NAFLD and serum phospholipid fatty acid composition. NAFLD was diagnosed by ultrasonography. The fatty acid composition between the control and NAFLD groups was compared, and the inverse probability of treatment weighting (IPTW) was performed to eliminate each confounding effect of sex, smoking status, BMI, insulin resistance, dietary cholesterol, and salt intake. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the NAFLD prediction accuracy of fatty acids. Seventy-one subjects were diagnosed with NAFLD. Their serum phospholipid dihomo-γ-linolenic acid (DGLA) level was significantly higher after adjusting for each variable using IPTW. In the ROC analysis, the ratio of ARA to DGLA had an area under the curve (AUC) of 0.763. By combining the ratio of ARA to DGLA with the ratio of AST to ALT, AUC increased to 0.871. In conclusion, NAFLD subjects in a Japanese working population have higher serum phospholipid DGLA. Results of the IPTW and ROC analysis indicated that serum PL DGLA and the ratio of ARA to DGLA provide diagnosis information on the fatty liver that is different to AST and ALT and improve the accuracy of fatty liver prediction, owning potential value as serum biomarkers.

Regulatory role of metallothionein-1/2 on development of sex differences in a high-fat diet-induced obesity.

AIMS: To evaluate the role of metallothionein (MT) in sex differences of obesity, we examined the effect of MT on regulation of lipid accumulation in female and male wild type (WT) and MT1/MT2-null (MT-KO) mice. MAIN METHODS: Male and female WT and MT-KO mice fed standard diet (SD) or high-fat diet (HFD) for 35 weeks. Surgical castration in male mice was also performed to examine the effects of androgen on fat accumulation under HFD condition. KEY FINDINGS: The fat mass and size of adipocytes in white adipose tissue (WAT) was greater in adult MT-KO mice than in WT mice after 35 weeks of SD feeding without gender differences, suggesting a role of MT in limiting WAT development during normal growth in both sexes. In female mice fed HFD, weights of WAT and body were greater in MT-KO mice than in WT mice, indicating that MT had a preventive role against excess fat accumulation. In male mice fed HFD, WAT weight hardly increased in MT-KO mice compared to the increase in WT mice. Surgically castrated WT males fed HFD had lower WAT weight compared with sham-treated mice, although castrated MT-KO males fed HFD had greater increases in WAT weight compared with sham-treated mice and castrated WT males. SIGNIFICANCE: These data suggest that MT could enhance the preventive action of estrogen against excess fat accumulation, on the contrary, MT augmented the ability of androgen to increase fat accumulation. MT may act to modify the susceptibility to obesity under sex hormones.

Starch synthase IIIa and starch branching enzyme IIb-deficient mutant rice line ameliorates pancreatic insulin secretion in rats: screening and evaluating mutant rice lines with antidiabetic functionalities.

Diabetes mellitus is a metabolic disease spreading worldwide that has been reported to worsen the development and progression of other diseases (cancer, vascular diseases and dementia). To establish functional rice lines with anti-postprandial hyperglycaemic effects, we developed mutant rice lines, which lack one or two gene(s) related to starch synthesis, and evaluated their effects. Powder of mutant rice lines or other grains was loaded to rats fasted overnight (oral grain powder loading test). Incremental area under time-concentration curves (iAUC) were calculated with monitored blood glucose levels. Rice lines with anti-postprandial hyperglycaemic effects were separated by cluster analysis with calculated iAUC. A double mutant rice #4019 (starch synthase IIIa (ss3a)/branching enzyme IIb (be2b)), one of the screened mutant rice lines, was fed to Goto-Kakizaki (GK) rats, an animal model for type 2 diabetes, for 5 weeks. Plasma levels of C-peptide, a marker of pancreatic insulin secretion, were measured with ELISA. For in vitro study, a rat pancreatic cell line was cultured with a medium containing rat serum which was sampled from rats fed #4019 diet for 2 d. After 24-h of incubation, an insulin secretion test was performed. Through the oral rice powder loading test, seven rice lines were identified as antidiabetic rice lines. The intake of #4019 diet increased plasma C-peptide levels of GK rats. This result was also observed in vitro. In rat serum added to cell medium, ornithine was significantly increased by the intake of #4019. In conclusion, the mutant rice #4019 promoted pancreatic insulin secretion via elevation of serum ornithine levels.

Circulating ferritin concentrations are differentially associated with serum adipokine concentrations in Japanese men and premenopausal women.

PURPOSE: Increased iron storage, as measured by circulating ferritin, has been linked to an increased risk of various diseases including diabetes. We examined the association of circulating ferritin with serum adiponectin, leptin, resistin, plasminogen activator inhibitor-1 (PAI-1), and visfatin levels. METHODS: We conducted a cross-sectional study among 429 Japanese employees (284 men and 145 premenopausal women, mean age: 42.5 ± 10.5 years). Serum adipokines were measured using Luminex suspension bead-based multiplexed array, and serum ferritin was determined using a chemiluminescence immunoassay. Multivariable regression analysis was performed to calculate mean concentrations of adipokine according to the tertile of ferritin concentrations with adjustment for potential confounders. RESULTS: Leptin and visfatin concentrations increased with increasing ferritin concentrations in men after multivariable adjustment of physical activity, smoking, alcohol use, and body mass index (P for trend = 0.02 and 0.01 for leptin and visfatin, respectively). Serum ferritin concentrations were inversely and significantly associated with adiponectin in women (P for trend = 0.01). Resistin and PAI-1 were not appreciably associated with ferritin concentration. CONCLUSIONS: Increased iron storage may be associated with higher circulating concentrations of leptin and visfatin in men and with lower concentrations of adiponectin in women.

The pathophysiological role of oxidized cholesterols in epicardial fat accumulation and cardiac dysfunction: a study in swine fed a high caloric diet with an inhibitor of intestinal cholesterol absorption, ezetimibe.

Oxidized cholesterols (oxycholesterols) in food have been recognized as strong atherogenic components, but their tissue distributions and roles in cardiovascular diseases remain unclear. To investigate whether accumulation of oxycholesterols is linked to cardiac morphology and function, and whether reduction of oxycholesterols can improve cardiac performance, domestic male swine were randomized to a control diet (C), high caloric diet (HCD) or HCD+Ezetimibe, an inhibitor of intestinal cholesterol absorption, group (HCD+E) and evaluated for: (1) distribution of oxycholesterol components in serum and tissues, (2) levels of oxycholesterol-related enzymes, (3) paracardial and epicardial coronary fat thickness, and (4) cardiac performance. Ezetimibe treatment for 8weeks attenuated increases in oxycholesterols in the HCD group almost completely in liver, but reduced only levels of 4ß-hydroxycholesterol in left ventricular (LV) myocardium. Ezetimibe treatment altered the expression of genes for cholesterol and fatty acid metabolism and decreased the expression of CYP3A46, which catabolizes cholesterol to 4ß-hydroxycholesterol, strongly in liver. An increase in epicardial fat thickness and impaired cardiac performance in the HCD group were improved by ezetimibe treatment, and the improvement was closely related to the reduction in levels of 4ß-hydroxycholesterol in LV myocardium. In conclusion, an increase in oxycholesterols in the HCD group was closely related to cardiac hypertrophy and dysfunction, as well as an increase in epicardial fat thickness. Ezetimibe may directly reduce oxycholesterol in liver and LV myocardium, and improve cardiac morphology and function.

Development and evaluation of rice giant embryo mutants for high oil content originated from a high-yielding cultivar 'Mizuhochikara'.

Rice bran oil is a byproduct of the milling of rice (Oryza sativa L.). It offers various health benefits and has a beneficial fatty acid composition. To increase the amount of rice bran as a sink for triacylglycerol (TAG), we developed and characterized new breeding materials with giant embryos. To induce mutants, we treated fertilized egg cells of the high-yielding cultivar 'Mizuhochikara' with N-methyl-N-nitrosourea (MNU). By screening M2 seeds, we isolated four giant embryo mutant lines. Genetic analysis revealed that the causative loci in lines MGE12 and MGE13 were allelic to giant embryo (ge) on chromosome 7, and had base changes in the causal gene Os07g0603700. On the other hand, the causative loci in lines MGE8 and MGE14 were not allelic to ge, and both were newly mapped on chromosome 3. The TAG contents of all four mutant lines increased relative to their wild type, 'Mizuhochikara'. MGE13 was agronomically similar to 'Mizuhochikara' and would be useful for breeding for improved oil content.

Probiotic Lactobacillus gasseri SBT2055 improves glucose tolerance and reduces body weight gain in rats by stimulating energy expenditure.

Probiotic Lactobacillus gasseri SBT2055 (LG2055) reduces postprandial TAG absorption and exerts anti-obesity effects in rats and humans; however, the underlying mechanisms are not fully understood. In the present study, we addressed the mechanistic insights of the anti-obesity activity of LG2055 by feeding Sprague-Dawley rats diets containing skimmed milk fermented or not by LG2055 for 4 weeks and by analysing energy expenditure, glucose tolerance, the levels of SCFA in the caecum and serum inflammatory markers. Rats fed the LG2055-containing diet demonstrated significantly higher carbohydrate oxidation in the dark cycle (active phase for rats) compared with the control group, which resulted in a significant increase in energy expenditure. LG2055 significantly reduced cumulative blood glucose levels (AUC) compared with the control diet after 3 weeks and increased the molar ratio of butyrate:total SCFA in the caecum after 4 weeks. Furthermore, the LG2055-supplemented diet significantly reduced the levels of serum amyloid P component - an indicator of the inflammatory process. In conclusion, our results demonstrate that, in addition to the inhibition of dietary TAG absorption reported previously, the intake of probiotic LG2055 enhanced energy expenditure via carbohydrate oxidation, improved glucose tolerance and attenuated inflammation, suggesting multiple additive and/or synergistic actions underlying the anti-obesity effects exerted by LG2055.

Deficiency of metallothionein-1 and -2 genes shortens the lifespan of the 129/Sv mouse strain.

Metallothionein (MT) family proteins are small molecular weight and cysteine-rich proteins that regulate zinc homeostasis and have potential protective effects against oxidative stress and toxic metals. To investigate whether MTs play a role in longevity determination in mammals, we measured the lifespans of wild-type (WT) and MT-1 and -2 gene knockout (MTKO) mice in a 129/Sv genetic background. MTKO mice of both sexes had shorter lifespans than WT mice. In particular, male MTKO mice living beyond the mean lifespan exhibited signs of weight loss, hunchbacked spines, lackluster fur and an absence of vigor. These results suggest that lifespan is shortened due to accelerated senescence in the absence of MT genes.

Habitual consumption of coffee and green tea in relation to serum adipokines: a cross-sectional study.

PURPOSE: Coffee and green tea consumption may be associated with circulating adipokines, but data are inconsistent, scarce or lacking. We examined the association of coffee and green tea consumption with serum adiponectin, leptin, visfatin, resistin and plasminogen activator inhibitor-1 (PAI-1) among a Japanese working population. METHODS: The authors analyzed data (n = 509) from a cross-sectional survey among Japanese workers aged 20-68 years. Serum adipokines were measured using a Luminex suspension bead-based multiplexed array. Coffee and green tea consumption was assessed using a validated diet history questionnaire, and caffeine consumption from these beverages was estimated. Multiple regression analysis was performed with adjustment for potential confounding variables. RESULTS: Coffee consumption was significantly, inversely associated with leptin and PAI-1 (P for trend = 0.007 and 0.02, respectively); compared with subjects consuming <1 cup per day, those consuming ≥4 cups per day had 13 and 10 % lower means of leptin and PAI-1, respectively. Similar associations were observed for caffeine consumption (P for trend = 0.02 for both leptin and PAI-1). Additionally, we noted a significant positive association between coffee consumption and adiponectin in men (P for trend = 0.046), but not in women (P for trend = 0.43, P for interaction = 0.11). Moreover, there was a positive association between coffee consumption and resistin in current male smokers (P for trend = 0.01), but not in male non-smokers (P for trend = 0.35, P for interaction = 0.11). Green tea consumption was not associated with any adipokine. CONCLUSIONS: Higher consumption of coffee and caffeine but not green tea was associated with lower serum levels of leptin and PAI-1 in Japanese adults.

Coffee intake is associated with lower levels of oxidative DNA damage and decreasing body iron storage in healthy women.

Habitual coffee drinking has been linked to a lower risk for some forms of cancer, but the mechanism remains elusive. Coffee may decrease oxidative DNA damage, an important pathway to carcinogenesis. We examined the association between coffee consumption and urinary 8-hydroxydeoxyguanosine (8-OHdG) concentrations, a biomarker of systemic oxidative DNA damage and repair, in 507 healthy subjects (298 men and 209 women aged 21-67 yr) while adjusting for age, sex, smoking status, body mass index, job type, and fasting blood glucose in multivariable regression models. The association with green tea consumption was also assessed. Urinary 8-OHdG concentrations tended to decrease with coffee consumption in women (trend P = 0.046), with women drinking 2-3 cups of coffee per day showing the lowest mean of urinary 8-OHdG concentrations. This association was largely attenuated after further adjustment for serum ferritin concentrations, a marker of body iron storage (trend P = 0.96). Green tea consumption was not associated with urinary 8-OHdG concentrations. Coffee drinking may be associated with decreased systemic oxidative DNA damage through decreasing body iron storage in women.

Increased serum GP88 (Progranulin) concentrations in rheumatoid arthritis.

GP88 (Progranulin; PGRN) is a secreted glycosylated protein with important functions in several processes, including immune response and cancer growth. Recent reports have shown that PGRN is a therapeutic target for rheumatoid arthritis (RA) because of its capability to bind with tumor necrosis factor receptor (TNFR). However, the serum PGRN level in RA patients has not been investigated. We used enzyme-linked immunosorbent assay (ELISA) to quantify the serum levels of PGRN in 417 healthy subjects, 56 patients with RA and 31 patients with osteoarthritis (OA). In RA patients, we also measured the serum TNF-α and sTNFR concentration. Immunohistochemical staining of PGRN was performed using synovectomy tissue of RA patients. The serum PGRN normal range was established as 40.1 ± 8.7 ng/ml. PGRN levels were not influenced by sex or age. A significant increase in serum PGRN levels was observed in RA (50.2 ± 11.1 ng/ml) and OA (45.4 ± 6.6 ng/ml) groups compared to those in age-matched healthy controls (40.4 ± 9.9 ng/ml) (p<0.05, Tukey). Further, PGRN levels in the synovial fluid of RA patients (68.4 ± 3.4 ng/ml) were found to be significantly higher than those in OA patients (35.9 ± 16.8 ng/ml). Immunohistochemical staining of PGRN revealed that the highest positive signal was detected in macrophages. Circulating PGRN in RA patients was weakly associated with TNF-α and sTNFR 2 concentration. Furthermore, PGRN/TNF-α ratio was correlated the stage of the disease in RA patients. The concentrations of serum PGRN in RA were found to be significantly higher than those in age-matched healthy controls, although it remains to be clarified how blood PGRN is related to the pathogenesis of RA. Our results showed that the serum PGRN may be a useful approach to monitor the disease activity in RA patients.

Clinical significance of brachial flow-mediated dilation in patients with rheumatoid arthritis.

AIM: This study aimed to clarify whether different anti-tumor necrosis factor (TNF) drugs can improve endothelial function better than conventional disease-modifying anti-rheumatic drugs (DMARDs) in a series of Japanese patients with rheumatoid arthritis (RA). METHOD: Twenty-five patients who met the American College of Rheumatology 1987 revised diagnostic criteria for RA were randomly selected for this study. The percentage of brachial flow-mediated dilation (%FMD) and maximum carotid intima-media thickness were examined by ultrasonography. RESULTS: The %FMD in the group treated with anti-TNF therapy was significantly higher than that in the group treated with DMARDs (P < 0.001). The %FMD was significantly correlated with anti-TNF therapy (r = 0.684, P < 0.001) and Disease Activity Score C-reactive protein (r = -0.404, P < 0.05). Multiple regression analysis revealed that anti-TNF therapy was significantly associated with %FMD (ß = 0.684, P < 0.001). CONCLUSION: Anti-TNF therapy may influence endothelial function more than conventional DMARD therapy. Prospective longitudinal studies examining whether anti-TNF therapy was able to improve endothelial function are required.

Prolonged endoplasmic reticulum stress alters placental morphology and causes low birth weight.

The role of endoplasmic reticulum (ER) stress in pregnancy remains largely unknown. Pregnant mice were subcutaneously administered tunicamycin (Tun), an ER stressor, as a single dose [0, 50, and 100 µg Tun/kg/body weight (BW)] on gestation days (GDs) 8.5, 12.5, and 15.5. A high incidence (75%) of preterm delivery was observed only in the group treated with Tun 100 µg/kg BW at GD 15.5, indicating that pregnant mice during late gestation are more susceptible to ER stress on preterm delivery. We further examined whether prolonged in utero exposure to ER stress affects fetal development. Pregnant mice were subcutaneously administered a dose of 0, 20, 40, and 60 µg Tun/kg from GD 12.5 to 16.5. Tun treatment decreased the placental and fetal weights in a dose-dependent manner. Histological evaluation showed the formation of a cluster of spongiotrophoblast cells in the labyrinth zone of the placenta of Tun-treated mice. The glycogen content of the fetal liver and placenta from Tun-treated mice was lower than that from control mice. Tun treatment decreased mRNA expression of Slc2a1/glucose transporter 1 (GLUT1), which is a major transporter for glucose, but increased placental mRNA levels of Slc2a3/GLUT3. Moreover, maternal exposure to Tun resulted in a decrease in vascular endothelial growth factor receptor-1 (VEGFR-1), VEGFR-2, and placental growth factor. These results suggest that excessive and exogenous ER stress may induce functional abnormalities in the placenta, at least in part, with altered GLUT and vascular-related gene expression, resulting in low infant birth weight.

Preventive effects of metallothionein against DNA and lipid metabolic damages in dyslipidemic mice under repeated mild stress.

The effects of repeated mild stress on DNA and lipid metabolic damages in multiple organs of dyslipidemic mice, and the preventive role of metallothionein (MT) were investigated. Female adult wild-type and MT-null mice fed high-fat diet (HFD) or standard diet (STD) were repeatedly subjected to fasting or restraint for three weeks. The liver, pancreas, spleen, bone marrow and serum samples were taken for evaluating DNA damage, MT, glutathione (GSH), corticosterone, carnitine and adiponectin. Body weights of restraint groups were reduced with the intensity of stress increased, even if the energy intakes were higher than those of STD group. Hepatic GSH levels were reduced in HFD control group and were further reduced in stress groups, especially in restraint groups, while the hepatic MT and serum corticosterone levels were increased in concert with the intensity of stress. Cellular DNA damages were generally increased by the restraint stress, especially in MT-null mice. Hepatic carnitine levels of MT-null mice were markedly lower than those of wild-type mice. The data suggest that MT plays a preventive role by acting as an antioxidant in corporation with GSH decreased by repeated stress and that MT may be an essential factor for inducing carnitine under the stress.

Cadmium modulates adipocyte functions in metallothionein-null mice.

Our previous study has demonstrated that exposure to cadmium (Cd), a toxic heavy metal, causes a reduction of adipocyte size and the modulation of adipokine expression. To further investigate the significance of the Cd action, we studied the effect of Cd on the white adipose tissue (WAT) of metallothionein null (MT(-/-)) mice, which cannot form atoxic Cd-MT complexes and are used for evaluating Cd as free ions, and wild type (MT(+/+)) mice. Cd administration more significantly reduced the adipocyte size of MT(-/-) mice than that of MT(+/+) mice. Cd exposure also induced macrophage recruitment to WAT with an increase in the expression level of Ccl2 (MCP-1) in the MT(-/-) mice. The in vitro exposure of Cd to adipocytes induce triglyceride release into culture medium, decrease in the expression levels of genes involved in fatty acid synthesis and lipid hydrolysis at 24 h, and at 48 h increase in phosphorylation of the lipid-droplet-associated protein perilipin, which facilitates the degradation of stored lipids in adipocytes. Therefore, the reduction in adipocyte size by Cd may arise from an imbalance between lipid synthesis and lipolysis. In addition, the expression levels of leptin, adiponectin and resistin decreased in adipocytes. Taken together, exposure to Cd may induce unusually small adipocytes and modulate the expression of adipokines differently from the case of physiologically small adipocytes, and may accelerate the risk of developing insulin resistance and type 2 diabetes.

Serum vitamin B6, folate, and homocysteine concentrations and oxidative DNA damage in Japanese men and women.

OBJECTIVE: Higher vitamin B status has been linked to a lower risk for cancer, but the underlying mechanism remains elusive. The aim of the present study was to examine the association of pyridoxal, folate, and homocysteine (Hcy) with urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage. METHODS: The participants were 500 employees (293 men and 207 women), ages 21 to 66 y, of two municipal offices in Japan. Serum pyridoxal and Hcy concentrations were measured using high-performance liquid chromatography (HPLC) method, and serum folate concentrations were measured using chemiluminescent immunoassay. Urinary 8-OHdG concentrations were measured using HPLC method. Multiple regression was used to estimate means of 8-OHdG for each tertile of pyridoxal, folate, and Hcy with adjustment for potential confounders. RESULTS: In multivariate analysis, 8-OHdG concentration was inversely associated with pyridoxal concentration in men (P for trend = 0.045) but not in women. The association in men was confined to non-smokers (P for trend = 0.033) or those who consumed no or < 20 g/d of ethanol (P for trend = 0.048). 8-OHdG concentrations were not appreciably associated with folate and Hcy concentrations. CONCLUSION: The results suggest that vitamin B6, but not folate and homocysteine, plays a role against oxidative DNA damage in Japanese men.

Lower serum levels of total cholesterol are associated with higher urinary levels of 8-hydroxydeoxyguanosine.

BACKGROUND: Lower serum total (TC), high-density lipoprotein (HDL-C) and low-density lipoprotein cholesterols (LDL-C) have been linked to an increased risk of cancer in various sites, but its underlying mechanism remains unclear. In an attempt to clarify the association between cholesterol levels and oxidative DNA damage, we investigated the relationship between serum cholesterol and urinary 8-hydroxydeoxyguanosine levels in a Japanese working population. METHODS: The study subjects were 294 men and 209 women aged 21-66 years in two Japanese municipal offices. Urinary 8-hydroxydeoxyguanosine (8-OHdG) was measured using an automated high-pressure liquid chromatography. Linear regression analysis was used to examine the associations of urinary 8-OHdG with TC, HDL-C and LDL-C levels with adjustment for sex, age, smoking and body mass index. Subgroup analyses were conducted by smoking status in men and age in women. Analysis of covariance was employed to estimate adjusted means of urinary 8-OHdG across TC category. RESULTS: After multivariate adjustment, urinary 8-OHdG levels were inversely associated with serum TC levels (ß = -0.0015, p < 0.05) and LDL-C levels (ß = -0.0012, p = 0.07). The inverse association with TC was apparent among smoking men (ß = -0.0017, p < 0.05) and among women aged less than 48 years (ß = -0.0040, p < 0.01). 8-OHdG decreased as TC increased (up to 219 mg/dL); subjects with TC levels of <160 mg/dL had a 17.4% higher adjusted mean of 8-OHdG than did those with TC levels of 200-219 mg/dL. CONCLUSION: Results suggest that circulating low TC levels are associated with higher oxidative DNA damage.