Retinoic acid (RA) plays an important role in bone metabolism in vivo through osteoclast activation and bone resorption. Retinoid X-activated receptor β (RXRβ) has been implicated in the genetic spinal defect of ossification of the posterior longitudinal ligament (OPLL). In this study, we examined the effects of 9-cis RA and all-trans RA (ATRA) on the proliferation, differentiation, and RXRβ expression of the murine preosteoblastic cell line MC3T3-E1. Both 9-cis RA and ATRA dose-dependently inhibited the increase in total soluble protein content at concentrations of 10 and 100nM after 4 and 8 d co-culture with MC3T3-E1 cells. The inhibitory effect of 9-cis RA was slightly stronger than that of ATRA. Histone H4 mRNA expression was dose-dependently suppressed by both RAs on day 1. Alkaline phosphatase activity was increased by both RAs at 10 and 100nM concentrations on day 4, with 9-cis RA-induced activity slightly stronger than that of ATRA. Osteopontin mRNA expression was increased by both RAs on day 1, but was suppressed on day 4. Bone Gla protein mRNA expression was inhibited by 10 and 100nM 9-cis RA and by 100nM ATRA on day 14. RXRβ mRNA expression was increased by 9-cis RA, an RXRβ ligand, in a dose-dependent manner. Our results suggested that while both RAs suppressed proliferation and stimulated the maturation of preosteoblastic MC3T3-E1 cells, 9-cis RA was slightly more potent than ATRA. It also appeared that RAs may contribute to the development of heterotopic ossification, including OPLL.
We investigated the levels of water-soluble vitamins except for vitamin B6 in the blood and urine of Japanese college male (n=10) and female (n=10) students. They consumed for 7 d a semi-purified diet based on Japanese Dietary Reference Intakes to assess the Recommended Dietary Allowances (RDA) for water-soluble vitamins and to present some new normal values for blood and urine levels of water-soluble vitamins in Japanese. The blood and the 24-h urine samples were collected on the last day of the experiment and mea sured. The values of total vitamin B1 in whole blood, total vitamin B2 in whole blood, total cyanocobalamin in serum, total nicotinamide in whole blood, total pantothenic acid in whole blood, total folates in serum, total biotin in serum, and ascorbic acid in plasma were 104 ± 17 pmol/mL (mean± SD), 216±25 pmol/mL, 0.34±0.05 pmol/mL, 59.1±5.0 nmol/mL, 2.45±0.37 nmol/mL, 15.6±4.6 pmol/mL, 8.3±0.5 pmol/mL, and 62±10 nmol/mL, respectively, in males, and 90±23, 234±18, 0.67±0.20, 61.9±6.0, 2.48±0.30, 30.2± 8.6, 8.4±0.3, and 67±14, respectively, in females. There was a significant difference in the values of cyanocobalamin and total folates between men and women. The urinary excretion of vitamin B1, vitamin B2, cyanocobalamin, sum of the catabolic metabolites of nicotinamide, pantothenic acid, folates, biotin, and ascorbic acid were 665± 114 nmol/d, 562±325 nmol/d, 93±31 pmol/d, 84±26μmol/d, 9.3±2.3μmol/d, 19.4±2.8 nmol/d, 83±18 pmol/d, and 148±51μmol/d, respectively, in males, and 495 ± 212, 580± 146, 145±49, 83±19, 16.9± 1.3, 22.7±2.7, 83±23, and 140±51, respectively, in females. There was a significant difference in the urinary excretion of cyanocobalamin, pantothenic acid and total folates between men and women. These values will be useful for the nutritional assess ment of water-soluble vitamins for Japanese, although the examination period was short. In future, an experiment with various age groups and re-evaluation by repeated experiments will provide more accurate values.
L-Histidine (histidine), a precursor of neuronal histamine, has recently been hypothesized to suppress food intake. The association between dietary histidine and energy intake was examined among 1, 689 Japanese female students of dietetic courses aged 18 y. Nutrient intakes were assessed over a 1-mo period with a validated, self-administered, diet history questionnaire. Both intake of histidine and the ratio of histidine to protein (histidine/ protein) statistically and positively correlated with energy intake. After adjustment for potential non-dietary confounding factors, including body height, body weight, physical activity level, and rate of eating, both the histidine intake and histidine/protein ratio statistically and positively correlated with energy intake (Pearson's correlation coefficient, r=0.62 and 0.12, respectively, p<0.001). Moreover, when protein or protein excluding histidine was additionally included into the covariates in order to minimize the effect of dietary factors and other amino acids, both histidine intake and histidinelprotein ratio turned out to show a statistically negative correlation with energy intake (r=-0.22 and -0.23, respectively, p<0.001). Considering the influence of unavoidable various covariates, we found an inverse association between histidinelprotein ratio and energy intake among the young female Japanese students.
To study the effects of the intake of green tea and polyphenols, which are a component of green tea, on insulin resistance and systemic inflammation, a randomized controlled trial was conducted on 66 patients aged 32-73 y (53 males and 13 females) with borderline diabetes or diabetes. Subjects in the intervention group were asked to take a packet of green tea extracts/powder containing 544 mg polyphenols (456 mg catechins) daily, which was a dose that could be taken without difficulty, and were asked to divide the green tea extracts/powder in a packet into 3 or 4 fractions dissolved in hot water everyday and to take a fraction after every meal or snack for 2 mo, in addition to daily food intake. The subjects in the control group were simply followed. To calculate the level of green tea polyphenol intake that the subject usually drank at home, the subject was asked to taste 3 teas of different strengths (1, 2 and 3%) and the tea that was closest to the one that the subject drank at home, was selected by each subject. After 2 mo, the mean daily polyphenol intake in the intervention group was 747mg, which was significantly higher than that of 469 mg in the control group. In the intervention group, the body weight, BMI, systolic and diastolic blood pressures, blood glucose level, Hb A1c level, insulin level and HOMA index after taking the supplementation for 2 mo, were lower than the respective value before intervention; however, these parameters in the intervention group at 2 mo did not significantly differ from those in the control group. Within the intervention group, changes in insulin level tended to be associated with changes in polyphenol intake. In addition, changes in BMI were associated with changes in blood glucose level and insulin level. In conclusion, the daily supplementary intake of 500mg green tea polyphenols did not have clear effects on blood glucose level, Hb A1c level, insulin resistance or inflammation markers. The positive correlation between the level of polyphenol intake and insulin level warrants further studies on the effect of green tea on insulin resistance.
This study examined the influence of a low level of dietary lectin (0.34%), at a dose that did not affect body weight or food intake, on the concentration of serum choles terol and fecal excretion of neutral sterols in rats fed a diet containing 0.50% cholesterol and 0.13% sodium cholate for 12 d. In experiment 1, rats fed a diet with 0.34% lectin, con canavalin A, had significantly lower concentrations of serum total cholesterol and hepatic cholesterol, a higher ratio of HDL-cholesterol to total cholesterol, enhanced excretion of fecal neutral sterols and reduced apparent cholesterol absorption or digestibility as com pared with rats fed a diet without lectin. Fecal excretion of acidic sterols was unaffected by dietary lectin. In contrast, dietary 0.34% lectin had no significant effect on concentrations of serum total protein or glucose. In experiment 2, we examined whether the cholesterol lowering activity of the lectin was responsibility for its carbohydrate-binding activity. The effect of dietary lectin on concentrations of serum and hepatic cholesterol and excretion of fecal neutral sterols was prevented by simultaneous administration of methyl-a-D-man nopyranoside with specific affinity for the carbohydrate-binding sites of the lectin. These results suggest that dietary lectins might reduce concentrations of serum and hepatic cho lesterol by a mechanism involving higher excretion of neutral sterols and that these alter ations might be associated with the carbohydrate-binding activity of lectin.
For effective exercise therapy after waking up, we focused on the staple food in diet therapy, and compared rice and bread diets. The subjects were 10 healthy college male students. After fasting for 12h or more from the previous day, the subjects had breakfast consisting of rice (protein, 6.3g; fat, 0.9g; CHO, 79.3g; energy, 368 kcal) or bread (protein, 15.7g; fat, 5.8g; CHO, 79.2g; and energy, 450 kcal) containing the same amount of carbohydrates and the same side dishes (protein, 7.0g; fat, 9.5g; CHO, 21.3g; energy, 199 kcal) in the morning 30 min before the initiation of exercise on a bicycle ergometer at an intensity of about 50% VO2max for 60min. Measurements of the heart rate and expired gas were initiated 15 min before the start of exercise and continued until 10 min after exercise. Blood was collected before the meal, immediately before and 15, 30, and 45 min after the initiation of exercise, and immediately, 15, and 30 min after its termination. After breakfast containing carbohydrates, decreases were observed in the levels of free fatty acid and noradrenalin. Blood insulin (mealXtime, p<Q.05 ANOVA) and triglyceride (mealXtime, p<0.01, ANOVA) changed at higher levels in the bread diet than in the rice diet. Blood triglyceride is a resource of fat synthesis/accumulation, and insulin promotes its action. Therefore, the bread diet may promote fat synthesis/accumulation compared with the rice diet.
The present study was designed to investigate the metabolic and sympathetic responses to a high-fat meal in humans. Fourteen young men (age: 23.6±0.5 y, BMI: 21.3±0.4 kg/m2) were examined for energy expenditure and fat oxidation measured by indirect calorimetry for 3.5h after a high-fat (70% energy from fat) or an isoenergetic lowfat (20% energy from fat) meal served in random order. The sympathetic nervous system (SNS) activity was assessed using power spectral analysis of heart rate variability (HRV). After the high-fat meal, increases in thermoregulatory SNS activity (very low-frequency component of HRV, 0.007-0.035 Hz, 577.4±45.9 vs. 432.0±49.3 ms2, p<0.05) and fat oxidation (21.0±5.3 vs. 13.3±4.3 g, p<0.001) were greater than those after the low-fat meal. However, thermic effects of the meal (TEM) were lower after the high-fat meal than after the low-fat meal (27.5±11.2 vs. 36.1±10.9 kcal, p<0.05). In conclusion, the high' fat meal can stimulate thermoregulatory SNS and lipolysis, but resulted in lower TEM, suggesting that a high proportion of dietary fat intake, even with a normal daily range of calories, may be a potent risk factor for further weight gain.
Oxidized frying oil (OFO) activates peroxisome proliferator-activated receptor a (PPAR a) in vitro and in vivo. As most PPARa activators are also Peroxisome proliferators (PP), this study was aimed at exploring whether OFO induces peroxisome proliferation in the liver of rats. Four groups of male weanling Sprague-Dawley rats were fed the following diets for 6 wk: a basal diet containing 5g/100g fresh soybean oil (LSB), high-fat diets con taining 20g/100g of fresh soybean oil (HSB as a control), OFO (HO) or fish oil (HF, as a pos itive control). Hepatomegaly and peroxisome proliferation in the liver of the HO group of rats were higher than those of the HF group. In addition, the acyl-CoA oxidase (ACO) activity, as well as cytochrome P450 4A (CYP4A) protein content in the livers of the HO group were 6 fold those of the HSB group, but were 2.5 fold in those of the HF group. These results indi cated that dietary OFO induced typical responses to PPARa signaling. Moreover, as a dietary source, the OFO prepared under our frying conditions appears to be a more potent peroxi some proliferator than fish oil.
The prolonging effect of Japanese kelp (kombu) on life span was investigated in mice fed a diet containing the carcinogen benzo[a]pyrene (BaP). Three groups of six mice each were fed a normal diet with 0, 2 and 5% kombu powder, while another three groups were fed those diets with 4 ppm BaP loading. The 2 and 5% kombu diets did not affect life span compared to the control group given 0% kombu. BaP significantly reduced the life span. Addition of 2 or 5% kombu to the BaP diet remarkably recovered the life span to a level similar to that of the control. The feces of the 2 and 5% kombu groups contained 6.9±1.2 and 16.8±1.8% of the ingested BaP, respectively, mainly in forms adsorbed on kombu fibers. The BaP-alone group given cellulose as dietary fiber instead of kombu, did not show any such effects. Humans are exposed to various environmental carcinogens such as BaP, and kombu fibers probably contribute to longevity by removing them.
This study clarified the influence of cigarette smoke on the L-ascorbic acid (AsA) metabolism and the activities of drug-metabolizing enzyme in rats. The test rats (group T) were exposed to weak sidestream smoke from cigarettes for 2 h, everyday for 5 7 days. AsA concentration in the tissues and excreted amount of AsA in urine of group T tended to be higher than those of control group (group C). The plasma AsA concentration and the activities of aniline hydroxylase and 7-ethoxycoumarin 0-deethylase of group T were significantly higher than those of group C. There was no significant difference in the activity of UDP glucuronosyltransferase or in the liver cytochrome P-450 content between these two groups.
This study dealt with the potential of fermented milk products as a source of functional casein phosphopeptides (CPPs) using plain yogurts and Camembert cheeses. The CPPs were prepared by tryptic digestion from four commercially available plain yogurts (P1-P4), five Camembert cheeses (C1-C5), and raw milk. From portions with a 1-g protein content of the plain yogurts, the Camembert cheeses, and the raw milk, 171mg, 139mg, and 146mg of CPPs were obtained, respectively. The Camembert cheeses retained high amounts of organic phosphorus (32μg) per 1 mg CPPs compared to the raw milk (15μg) and plain yogurts (16μg). Reverse-phase high-performance liquid chromatographic analysis showed that the elution patterns and retention times of the three major peaks of CPPs from P1 and C1 were similar to those from raw milk, Moreover, CPPs from P 1 and C 1 showed a mitogenic effect, while CPPs from Cl showed an IgA-enhancing effect in mouse spleen cell cultures. These results suggest that fermented milk products such as plain yogurts and Camembert cheeses generate functional CPPs in the body and exert beneficial effects on the immune system.
Antidiabetic effects of ajoene, derived from garlic, were investigated in genetically diabetic KK-Ay mice. Four-week-old male KK-Ay mice were kept on a laboratory diet containing 0.02 or 0.05% of ajoene for 8 wk. The elevation of water intake was suppressed depending on ajoene intake. The levels of plasma glucose in the 0.05% ajoene-containing diet group was significantly suppressed to 73.8% compared with the control group at the 8th wk. Similarly, the plasma triglyceride level was significantly suppressed. It is suggested that hyperglycemia and hypertriglyceridemia are suppressed by ajoene treatment.