Ichiro Tokimitsu

Anti-obesity effect of dietary diacylglycerol in C57BL/6J mice dietary diacylglycerol stimulates intestinal lipid metabolism

We examined the long-term effects of dietary diacylglycerol (DG) and triacylglycerol (TG) with similar fatty acid compositions on the development of obesity in C57BL/6J mice. We also analyzed the expression of genes involved in lipid metabolism at an early stage of obesity development in these mice. Compared with mice fed the high-TG diet, mice fed the high-DG diet accumulated significantly less body fat during the 8-month study period. Within the first 10 days, dietary DG stimulated β-oxidation and lipid metabolism-related gene expression, including acyl-CoA oxidase, medium-chain acyl-CoA dehydrogenase, and uncoupling protein-2 in the small intestine but not in the liver, skeletal muscle, or brown adipose tissue, suggesting the predominant contribution of intestinal lipid metabolism to the effects of DG. Furthermore, analysis of digestion products of [14C]DG and those of [14C]TG revealed that the radioactivity levels detected in fatty acid, 1-monoacylglycerol, and 1,3-DG in intestinal mucosa were significantly higher after intrajejunal injection of DG rather than TG. Thus, dietary DG reduces body weight gain that accompanies the stimulation of intestinal lipid metabolism, and these effects may be related to the characteristic metabolism of DG in the small intestine.

Chlorogenic acid attenuates hypertension and improves endothelial function in spontaneously hypertensive rats.

Background and objectives Epidemiologic studies indicate that ingestion of vegetables and fruit inhibits the development of cardiovascular disease. Chlorogenic acids are abundant phenolic compounds contained in vegetables and fruits, but the impact of dietary chlorogenic acids on vascular function in hypertension is not known. We therefore examined the effects of 5-caffeoylquinic acid (CQA), a representative chlorogenic acid, on blood pressure and vascular function in age-matched normotensive Wistar–Kyoto rats and spontaneously hypertensive rats. Methods and results A single ingestion of CQA (30–600 mg/kg) reduced blood pressure in spontaneously hypertensive rats, an effect that was blocked by administration of a nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester. When spontaneously hypertensive rats were fed diets containing 0.5% CQA for 8 weeks (approximately 300 mg/kg per day), the development of hypertension was inhibited compared with the control diet group. CQA ingestion increased urinary excretion of nitric oxide metabolites and decreased urinary excretion of hydrogen peroxide; decreased NADPH-dependent superoxide anion production in the aorta, suggesting that dietary CQA inhibited vascular NADPH oxidase activity; significantly improved acetylcholine-induced endothelium-dependent vasodilation in the aorta; and markedly reduced the degree of immunohistochemical staining for nitrotyrosine and media hypertrophy in aorta sections. In contrast, CQA had no effects in Wistar–Kyoto rats. Conclusions Dietary CQA reduces oxidative stress and improves nitric oxide bioavailability by inhibiting excessive production of reactive oxygen species in the vasculature, and leads to the attenuation of endothelial dysfunction, vascular hypertrophy, and hypertension in spontaneously hypertensive rats.

Gallates Inhibit Cytokine-Induced Nuclear Translocation of NF-κB and Expression of Leukocyte Adhesion Molecules in Vascular Endothelial Cells

Gallates (gallic acid esters) belong to the class of phenolic compounds, which are abundant in red wine. In this study, we show that gallates can inhibit cytokine-induced activation of nuclear factor kappaB (NF-kappaB) and thereby reduce expression of endothelial-leukocyte adhesion molecules in cultured human umbilical vein endothelial cells (HUVECs). Pretreatment of HUVECs with ethyl gallate (3 to 10 micromol/L) significantly suppressed interleukin-1alpha (IL-1alpha)- or tumor necrosis factor-alpha (TNF-alpha)- induced mRNA and cell-surface expression of vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin, which was associated with reduced adhesion of leukocytes to HUVECs. Gel shift assays with the NF-kappaB consensus sequence showed the decreased densities of the shifted bands in gallate-treated HUVECs. Furthermore, gallate pretreatment inhibited cytokine-induced transcription of a fusion gene, which consisted of 4 repeats of the NF-kappaB consensus sequence and the luciferase reporter gene. Immunoblot analysis of nuclear extracts and whole-cell lysates demonstrated the decreased amounts of NF-kappaB p65 in nuclei but equal amounts of inhibitor-kappaBalpha (I-kappaBalpha) in whole-cell lysates of ethyl gallate-treated HUVECs. Incubation of the nuclear extracts from cytokine-activated HUVECs with ethyl gallate did not affect the NF-kappaB shifted bands induced by cytokines in gel shift assays. Taken together, these data demonstrate that ethyl gallate can inhibit cytokine-induced nuclear translocation of NF-kappaB p65 by way of a mechanism independent of I-kappaBalpha degradation and thereby suppress expression of VCAM-1, ICAM-1, and E-selectin, which was associated with reduced adhesion of leukocytes. These results in vitro demonstrate that gallates can exhibit anti-inflammatory properties by blocking activation of NF-kappaB and suggest that these natural compounds, abundant in red wine, may play important roles in the prevention of atherosclerosis and inflammatory responses in vivo.

RS4-type resistant starch prevents high-fat diet-induced obesity via increased hepatic fatty acid oxidation and decreased postprandial GIP in C57BL/6J mice

Chemically modified starches (CMS) are RS4-type resistant starch, which shows a reduced availability, as well as high-amylose corn starch (HACS, RS2 type), compared with the corresponding unmodified starch. Previous studies have shown that RS4 increases fecal excretion of bile acids and reduces zinc and iron absorption in rats. The aim of this study was to investigate the effects of dietary RS4 supplementation on the development of diet-induced obesity in mice. Weight- and age-matched male C57BL/6J mice were fed for 24 wk on a high-fat diet containing unmodified starch, hydroxypropylated distarch phosphate (RS4), or HACS (RS2). Those fed the RS4 diet had significantly lower body weight and visceral fat weight than those fed either unmodified starch or the RS2 diet. Those fed the RS4 diet for 4 wk had a significantly higher hepatic fatty acid oxidation capacity and related gene expression and lower blood insulin than those fed either unmodified starch or the RS2 diet. Indirect calorimetry showed that the RS4 group exhibited higher energy expenditure and fat utilization compared with the RS2 group. When gavaged with fat (trioleate), RS4 stimulated a lower postprandial glucose-dependent insulinotropic polypeptide (GIP; incretin) response than RS2. Higher blood GIP levels induced by chronic GIP administration reduced fat utilization in high-fat diet-fed mice. In conclusion, dietary supplementation with RS4-type resistant starch attenuates high-fat diet-induced obesity more effectively than RS2 in C57BL/6J mice, which may be attributable to lower postprandial GIP and increased fat catabolism in the liver.

Different contribution of muscle and liver lipid metabolism to endurance capacity and obesity susceptibility of mice

We investigated strain differences in whole body energy metabolism, peripheral lipid metabolism, and energy metabolism-related gene expression and protein levels in BALB/c, C57BL/6J, and A/J mice to evaluate the relationship between endurance capacity, susceptibility to diet-induced obesity, and differences in lipid metabolism in muscle and liver. A high-fat diet significantly increased body weight and fat weight in C57BL/6J mice, but not in BALB/c and A/J mice. The endurance capacity of BALB/c mice was 52% greater than that of C57BL/6J mice and 217% greater than that of A/J mice. The respiratory exchange ratio was lowest in BALB/c mice, higher in C57BL/6J mice, and highest in A/J mice, which inversely correlated with the endurance capacity and fatty acid beta-oxidation activity in the muscle. Plasma lactate levels measured immediately after exercise were lowest in BALB/c mice and highest in A/J mice, although there was no difference under resting conditions, suggesting that carbohydrate breakdown is suppressed by enhanced fat utilization during exercise in BALB/c mice. On the other hand, the body weight increase induced by high-fat feeding was related to a reduced whole body energy expenditure, higher respiratory quotient, and lower fatty acid beta-oxidation activity in the liver. In addition, beta-oxidation activity in the muscle and liver roughly paralleled the mRNA and protein levels of lipid metabolism-related molecules, such as peroxisome proliferator-activated receptor and medium-chain acyl-CoA dehydrogenase, in each tissue. These findings indicate that genetically determined basal muscle and liver lipid metabolism and responsiveness to exercise influence physical performance and obesity susceptibility.

Reduction of Streptococcus mutans Adherence and Dental Biofilm Formation by Surface Treatment with Phosphorylated Polyethylene Glycol

ABSTRACT Initial attachment of the cariogenic Streptococcus mutans onto dental enamel is largely promoted by the adsorption of specific salivary proteins on enamel surface. Some phosphorylated salivary proteins were found to reduce S. mutans adhesion by competitively inhibiting the adsorption of S. mutans-binding salivary glycoproteins to hydroxyapatite (HA). The aim of this study was to develop antiadherence compounds for preventing dental biofilm development. We synthesized phosphorylated polyethylene glycol (PEG) derivatives and examined the possibility of surface pretreatment with them for preventing S. mutans adhesion in vitro and dental biofilm formation in vivo. Pretreatment of the HA surface with methacryloyloxydecyl phosphate (MDP)-PEG prior to saliva incubation hydrophilized the surface and thereby reduced salivary protein adsorption and saliva-promoted bacterial attachment to HA. However, when MDP-PEG was added to the saliva-pretreated HA (S-HA) surface, its inhibitory effect on bacterial binding was completely diminished. S. mutans adhesion onto S-HA was successfully reduced by treatment of the surface with pyrophosphate (PP), which desorbs salivary components from S-HA. Treatment of S-HA surfaces with MDP-PEG plus PP completely inhibited saliva-promoted S. mutans adhesion even when followed by additional saliva treatment. Finally, mouthwash with MDP-PEG plus PP prevented de novo biofilm development after thorough teeth cleaning in humans compared to either water or PP alone. We conclude that MDP-PEG plus PP has the potential for use as an antiadherence agent that prevents dental biofilm development.

Effects of Diacylglycerol Oil on Adiposity in Obese Children: Initial Communication

Several studies have shown that diacylglycerol (DAG) oil may suppress accumulation of body fat in adults compared to triacylglycerol (TAG) oil. In this study, we investigated the effect of DAG oil as part of dietetic therapy in obese children. The participants were 11 male and female obese children who were under treatment at the outpatient clinic (four boys, seven girls, age: 7-17 years old). Daily-use cooking oil was changed to DAG oil, and the effects on abdominal fat areas, adipocytokines, and serum lipids were investigated. The total and subcutaneous fat areas significantly decreased in the 5th month after ingestion of DAG oil. Leptin was significantly lower than the initial level after ingestion of DAG oil. The ingestion of DAG oil decreased both the abdominal fat area and leptin in obese children, suggesting that DAG oil prevents obesity in children as well as in adults.

Effects of Dietary Diacylglycerol on the Energy Metabolism

In the present study, we characterized diacylglycerol (DAG) oil in terms of energy metabolism by comparing oxygen consumption and respiratory quotient (RQ), as well as blood parameters, in rats after administration of emulsions containing either DAG or triacylglycerol (TAG) with similar fatty acid composition. Twelve male Wistar rats (250-280 g) were acclimatized, and then catheterized into the stomach, and held individually in Bollman restraining cages. After 24 hours fasting, each emulsion containing either DAG or TAG (10 g/kg body weight) was infused. Oxygen consumption and fat oxidation in the DAG group gradually increased after administration of the DAG emulsion and became significantly higher than those of the TAG group. RQ in both groups dropped after administration of emulsion, but the values of the DAG group were significantly lower than that of the TAG group. The postprandial serum triglyceride level was significantly increased from 60 minutes after administration in the TAG group, and 240 minutes in the DAG group, compared to the preprandial level. The serum triglyceride level tended to be lower in the DAG group than in the TAG group at 60 minutes and thereafter, and the statistical difference between the TAG and DAG groups was significant at 300 minutes after administration. These results suggest that DAG oil infusion might lead to higher energy expenditure and lipids oxidation compared to TAG oil with a similar fatty acid composition.

Effectiveness and safety of 1-year ad libitum consumption of a high-catechin beverage under nutritional guidance.

BACKGROUND It has been reported that a continuous intake of a catechin beverage will reduce body fat. Traditionally, improvement of eating and exercise habits has been the basis for prevention and reduction of obesity. In this study, we conducted a trial involving human subjects who ingested a catechin beverage for 1 year under nutritional guidance. METHODS This study was conducted based on a comprehensive cohort design using a catechin beverage (containing 588 mg of tea catechins) and a control beverage (containing 126 mg of tea catechins). At both the start and the end of the trial, the subjects underwent an annual health check and computer tomography for measurement of their abdominal fat. In addition, a food intake survey was conducted and all subjects were provided nutritional guidance by a registered dietitian every 3 months. RESULTS Data were analyzed using per protocol samples of 134 subjects (catechin group, n = 77; control group, n = 57). Body weight and body mass index were reduced significantly in the catechin group compared to the control group. Changes in body weight during the study period were -1.1 kg in the catechin group and 0.2 kg in the control group. In the catechin group, the visceral fat areas at the start of the trial were significantly correlated with the magnitude of fat reduction at the end of the trial. Under the guidance of a registered dietitian, subjects in the catechin group who showed a reduction in their fat-derived energy percentage during the test period tended to reduce more body weight than those with an increase in this percentage, although no difference in total energy intake was noted between the two groups. One-year ad libitum consumption of a catechin beverage posed no health risks and resulted in a reduction in body weight. CONCLUSIONS An overall improvement in dietary habits might enhance the weight-reduction effect of the beverage.

478—Theory of Brdička current and the dependence of the current on cobalt ion concentration

Abstract An equation of Brdicka current and its experimental verification are presented, in which Brdicka current is expressed by a function of the surface concentration of protein, the bulk concentration of cobalt ion and two parameters, nckc and kf/kd, characterizing the protein-zero-valent cobalt complex which is to catalize the hydrogen evolution, where nc is the total number of sites on which the complex can be formed in a protein molecule, and kc and kd are the (average) constants representing the intrinsic catalytic activity and the lifetime respectively, of the complex.