Dietary High-Dose Biotin Intake Activates Fat Oxidation and Hepatic Carnitine Palmitoyltransferase in Rat.

This study investigated the effects of dietary high-dose biotin intake on fat oxidation in rats using respiratory gas analysis, and evaluated fatty-acid oxidation-related enzyme activities and gene expressions in the liver. Five-week-old male Sprague-Dawley rats were fed a control diet and three biotin-supplemented diets (additive biotin concentration: 0.05%, 0.10%, and 0.20% of diet) for 3 wk. In 2 wk, fat oxidation in the 0.20% biotin-supplemented diet group was higher than that in the 0.05% biotin-supplemented diet group; however, the energy expenditure and carbohydrate oxidation were unchanged between the dietary groups. At the end of 3 wk, body weight and epididymal white adipose tissue weight reduced in the 0.20% biotin diet group, and hepatic triglyceride levels tended to decrease. Additionally, increased plasma adiponectin concentration and hepatic mitochondrial carnitine palmitoyltransferase activity as well as decreased hepatic acetyl-CoA carboxylase 2 gene expression were observed in the 0.20% biotin-supplemented diet group compared with those in the control group. These results provide strong evidence that dietary high-dose biotin intake activated fat oxidation due to the increase in hepatic ß-oxidation, which may contribute to the decrease in hepatic triglyceride concentration and white adipose tissue weight.

Oral administration of green algae, Euglena gracilis, inhibits hyperglycemia in OLETF rats, a model of spontaneous type 2 diabetes.

In the present study, the effects of Euglena and paramylon on hyperglycemia were examined in Otsuka Long-Evans Tokushima fatty (OLETF; type 2 diabetes mellitus model) rats. OLETF rats were fed an AIN-93 M diet containing cellulose, Euglena, or paramylon for 10 weeks. Long-Evans Tokushima Otsuka (LETO) rats were used as nondiabetic controls. An oral glucose-tolerance test (OGTT) was performed at 0 and 10 weeks. OLETF control rats were obese because of bulimia and showed abdominal fat accumulation and hyperglycemia. Euglena supplementation improved hyperglycemia and decreased food intake, body weight gain, and abdominal fat. However, there were no changes in the paramylon-supplemented group compared to the OLETF control group. Triglyceride concentrations in the serum and liver were lower in Euglena-supplemented rats than in OLETF control rats. There was a correlation between hepatic triglyceride concentration and the area under the curve (AUC) of OGTT at 10 weeks. This suggests that the improvement in glycemic control in the Euglena-supplemented group may depend on substances other than paramylon present in Euglena.

Effects of Biotin Deficiency on Biotinylated Proteins and Biotin-Related Genes in the Rat Brain.

Biotin is a water-soluble vitamin that functions as a cofactor for biotin-dependent carboxylases. The biochemical and physiological roles of biotin in brain regions have not yet been investigated sufficiently in vivo. Thus, in order to clarify the function of biotin in the brain, we herein examined biotin contents, biotinylated protein expression (e.g. holocarboxylases), and biotin-related gene expression in the brain of biotin-deficient rats. Three-week-old male Wistar rats were divided into a control group, biotin-deficient group, and pair-fed group. Rats were fed experimental diets from 3 wk old for 8 wk, and the cortex, hippocampus, striatum, hypothalamus, and cerebellum were then collected. In the biotin-deficient group, the maintenance of total biotin and holocarboxylases, increases in the bound form of biotin and biotinidase activity, and the expression of an unknown biotinylated protein were observed in the cortex. In other regions, total and free biotin contents decreased, holocarboxylase expression was maintained, and bound biotin and biotinidase activity remained unchanged. Biotin-related gene (pyruvate carboxylase, sodium-dependent multivitamin transporter, holocarboxylase synthetase, and biotinidase) expression in the cortex and hippocampus also remained unchanged among the dietary groups. These results suggest that biotin may be related to cortex functions by binding protein, and the effects of a biotin deficiency and the importance of biotin differ among the different brain regions.

Dietary intake of high-dose biotin inhibits spermatogenesis in young rats.

To characterize a new function of the water-soluble vitamin, biotin, in reproduction and early growth in mammals, the effects of high dietary doses of biotin on early spermatogenesis were biochemically and histologically investigated in male rats. Weaned rats were fed a CE-2 (control) diet containing 0.00004% biotin, or a control diet supplemented with 0.01%, 0.1%, or 1.0% biotin. Pair-fed rats were fed a control diet that was equal in calories to the amount ingested by the 1.0% biotin group, because food intake was decreased in the 1.0% biotin group. Food intake and body weight gain were lower in the 1.0% biotin group than in the control group. The kidney, brain and testis weights were significantly lower in the 1.0% biotin group than in the pair-fed group after 6 weeks of feeding. The accumulation of biotin in the liver and testis increased in a dose-dependent manner. In the 1.0% biotin group, the number of mature sperm was markedly lower, that of sperm with morphologically abnormal heads, mainly consisting of round heads, had increased. In addition, the development of seminiferous tubules was inhibited, and few spermatogonia and no spermatocytes were histologically observed. These results demonstrated that the long-term intake of high-dose biotin inhibited spermatogenesis in young male rats.

Antitumor activity of the ß-glucan paramylon from Euglena against preneoplastic colonic aberrant crypt foci in mice.

In the present study, the effects of ß-glucans isolated from Euglena on the formation of preneoplastic aberrant crypt foci (ACF) in the colon were examined in mice. Mice were fed a semi-purified AIN-93M diet containing cellulose or the same diet but with the cellulose replaced with ß-glucans in the form of Euglena, paramylon, or amorphous paramylon, for 11 weeks. After consuming these dietary supplements for 8 days, half of the mice were intraperitoneally administered 1,2-dimethylhydrazine (DMH) at a dose of 20 mg kg(-1) body weight every week for 6 weeks. Among the DMH-treated groups, the paramylon- and amorphous paramylon-fed mice displayed a significantly lower number of ACF than the control group. Also, the liver weight of the paramylon group was markedly decreased compared with those of the control and Euglena groups, whereas the cecal content weight and fecal volume of the paramylon group were significantly increased. As for the levels of organic acids in the cecal contents, the paramylon group displayed significantly increased lactic acid levels compared with the control and Euglena groups. From these findings, although the mechanism of the ACF-inhibiting effects of paramylon remains unclear, it is considered that ß-glucans, such as paramylon and its isomer amorphous paramylon, have preventive effects against colon cancer and are more effective against the condition than Euglena.

Consumption of a low-carbohydrate and high-fat diet (the ketogenic diet) exaggerates biotin deficiency in mice.

OBJECTIVE: Biotin is a water-soluble vitamin that acts as a cofactor for several carboxylases. The ketogenic diet, a low-carbohydrate, high-fat diet, is used to treat drug-resistant epilepsy and promote weight loss. In Japan, the infant version of the ketogenic diet is known as the "ketone formula." However, as the special infant formulas used in Japan, including the ketone formula, do not contain sufficient amounts of biotin, biotin deficiency can develop in infants who consume the ketone formula. Therefore, the aim of this study was to evaluate the effects of the ketogenic diet on biotin status in mice. METHODS: Male mice (N = 32) were divided into the following groups: control diet group, biotin-deficient (BD) diet group, ketogenic control diet group, and ketogenic biotin-deficient (KBD) diet group. Eight mice were used in each group. RESULTS: At 9 wk, the typical symptoms of biotin deficiency such as hair loss and dermatitis had only developed in the KBD diet group. The total protein expression level of biotin-dependent carboxylases and the total tissue biotin content were significantly decreased in the KBD and BD diet groups. However, these changes were more severe in the KBD diet group. CONCLUSION: These findings demonstrated that the ketogenic diet increases biotin bioavailability and consumption, and hence, promotes energy production by gluconeogenesis and branched-chain amino acid metabolism, which results in exaggerated biotin deficiency in biotin-deficient mice. Therefore, biotin supplementation is important for mice that consume the ketogenic diet. It is suggested that individuals that consume the ketogenic diet have an increased biotin requirement.

Characterization of microorganisms at different landfill depths using carbon-utilization patterns and 16S rRNA gene based T-RFLP.

A borehole core from 20 m depth of a Japanese landfill was characterized chemically and microbially. The borehole core sample was typically divided into 5 waste layers; 2.4-4.0 m, 5.7-8.5 m, 9.25-9.6 m, 9.77-14.9 m, and 15.9-17.86 m depths. The waste layers' ages spanned about 14 years between the bottom and top. Archaeal 16S rRNA gene and eubacterial 16S rRNA gene in the waste samples at their respective levels were 9.8 x 10(5)-7.2 x 10(7) and 1.2 x 10(7)-7.2 x 10(9) copy/g-wet. Similar to populations of viable and culturable bacteria, those populations were high at 7.0 m and 17.5 m depth, but low at 3.0 m depth. The microorganisms' phenotypes and genotypes were evaluated, respectively, using carbon-utilization tests and by eubacterial 16S rRNA gene based T-RFLP. Low dominance of the VFA-utilizing bacteria in samples and low concentrations of VFAs in all waste layers suggest that the organic decomposition in this landfill site remained. Gamma-proteobacteria dominated the microbial community at 17.5 m depth. Clostridia were detected at 7.0, 11.5, and 17.5 m depths, suggesting strict anaerobic conditions in these deep layers. The Shannon-Weaver diversity index showed lower values at 3.0 m and 11.5 m depth with a T-RF pattern. The diversity index calculated from the carbon-utilization pattern increased slightly with depth at the landfill site. The landfill-site waste layers are expected to be mutually isolated and to form unique microbial communities depending on the buried wastes' composition, temperature, moisture content, and pressure inside the landfill.

Validation of the association of genetic variants on chromosome 9p21 and 1q41 with myocardial infarction in a Japanese population.

BACKGROUND: Recent large-scale genome-wide association studies have identified several loci associated with the risk of coronary artery disease (CAD). The aim of the present study was to examine whether the previously reported CAD-associated single-nucleotide polymorphisms (SNPs) confer susceptibility to myocardial infarction (MI) in a study population of 2,475 controls and 589 cases of MI. The effect of the CAD-associated SNPs on cardiovascular risk factors in the control group was also investigated. METHODS AND RESULTS: Significant associations were observed between 2 SNPs, rs1333049 on chromosome 9p21 and rs17465637 on chromosome 1q41, and MI, with odds ratios adjusted for age, sex, diabetes, hypertension and smoking habit of 1.47 (95% confidence interval (CI), 1.15-1.89; corrected p=0.006) and 1.45 (95%CI, 1.15-1.83; corrected p=0.006) for rs1333049 and rs17465637, respectively. None of the genotypes was associated with body mass index, plasma lipid profile, blood pressure, glucose, or hemoglobin A1c. The genotypes also had no effect on the marker of inflammation (C-reactive protein) or atherosclerosis (mean and maximum carotid intima-media thickness). CONCLUSIONS: Although the underlying mechanisms are not clearly understood, the previously reported association between the 2 SNPs (rs1333049 and rs17465637) and MI was reproduced in this Japanese sample.

Inhalation exposure to carbon black induces inflammatory response in rats.

BACKGROUND: A link between exposure to fine particulate matter and cardiovascular events has been established. Inhaled nanoparticles are thought to pass through the lungs to reach other tissues via systemic circulation and to induce cell or tissue injuries. It was recently shown that long-term exposure to intra-tracheal dispersion of nano-sized carbon black (CB) exacerbates atherosclerotic lesions in low-density lipoprotein receptor-deficient mice. Because intra-tracheal dispersion of CB may be associated with aggregate formation and may not be an ideal method for CB exposure, whole-body inhalation exposure was used in the present study, the aim of which was to examine whether exposure of rats to nano-sized CB particles by inhalation leads to translocation of these particles into the circulation, exerting direct adverse effects on extrapulmonary tissues. METHODS AND RESULTS: Sprague-Dawley rats were exposed to a high dose of CB or filtered air for 6 h/day, 5 days a week for a total of 4 weeks. Although the presence of CB was confirmed in pulmonary macrophages, electron microscopic survey did not detect CB in other tissues including liver, spleen and aorta. CB exposure raised blood pressure levels in an exposure-time dependent manner. Levels of circulating inflammatory marker proteins, including monocyte chemoattractant protein-1, interleukin-6, and C-reactive protein, were higher in the CB-treated group than in the controls. CONCLUSION: Evidence of translocation of inhaled CB was not obtained. It is likely that inhaled nano-sized CB particles form aggregations in the lung and do not exert direct adverse effects on extrapulmonary tissues. Air-pollution-mediated cardiovascular events appear to be induced by the low-grade inflammatory response to the accumulation of aggregated nano-sized particles in the lung.

Effects of excess biotin administration on the growth and urinary excretion of water-soluble vitamins in young rats.

To determine the effects of excess biotin administration on growth and water-soluble vitamin metabolism, weaning rats were fed on a 20% casein diet containing 0.00002% biotin, or same diet with 0.04, 0.08, 0.10, 0.20, 0.50, 0.80 or 1.0% added biotin for 28 days. More than 0.08% biotin administration decreased the food intake and body weight gain compared with the levels in control rats. An accumulation of biotin in such tissues as the liver, brain and kidney increased in a dose-dependent manner, and the both bound and free biotin contents in the liver also increased in a dose-dependent manner. An excess administration of biotin did not affect the urinary excretion of other water-soluble vitamins, suggesting no effect on the metabolism of other water-soluble vitamins. The results of the food intake and body weight gain indicated that the lowest observed adverse effect level for young rats was 79.2 mg/kg body weight/day, while the no observed adverse effect level was 38.4 mg/kg/day. These results suggested immediately setting a tolerable upper intake level for biotin.