We have previously reported that rats fed on a vitamin B₁₂ (B₁₂)-deficient diet containing 180 g soybean protein per kg diet showed marked histologic damage in their testes. In this paper, we report the effect of B₁₂-deficiency on B₁₂-dependent methionine synthase in the rats' testes and the effect of methionine supplementation of the diet on testicular damage. Rats were fed the soybean protein-based B₁₂-deficient diet for 120 d. We confirmed that those rats were in serious B₁₂-deficiency by measuring urinary methylmalonic acid excretion and B₁₂ content in tissues. Methionine synthase activity in the testis of the B₁₂-deficient rats was less than 2% of that in B₁₂-supplemented (control) rats. To complement disrupted methionine biosynthesis, methionine was supplied in the diet. A supplement of 5 g D,L-methionine per kg diet to the B₁₂-deficient diet did not affect urinary methylmalonic acid excretion of B₁₂-deficient rats. The testicular histology of rats fed the methionine-supplemented B₁₂-deficient diet was almost indistinguishable from that of control rats. Thus, we conclude that the lowered testicular methionine synthase activity is the primary cause of the histologic damage due to B₁₂-deficiency and that methionine supplementation to the diet can reduce the damage. These findings would indicate the importance of the methionine synthase activity, especially for testicular function.

View full abstract

Adenosylcobalamin-dependent diol dehydratase and glycerol dehydratase are isofunctional enzymes that catalyze the dehydration of 1,2-diols to the corresponding aldehydes. Although they bear different metabolic roles, both enzymes consist of three different subunits and possess a common (αβγ)₂ structure. To elucidate the roles of each subunit, we constructed expression plasmids for the hybrid dehydratases between diol dehydratase of Klebsiella oxytoca and glycerol dehydratase of Klebsiella pneumoniae in all the combinations of subunits by gene engineering techniques. All of the hybrid enzymes were produced in Escherichia coli at high levels, but only two hybrid enzymes consisting of the α subunit from glycerol dehydratase and the β subunits from diol dehydratase showed high activity. The substrate specificity, the susceptibility to inactivation by glycerol, and the monovalent cation specificity of the wild type and hybrid enzymes were primarily determined by the origin of their α subunits.

View full abstract

This study was carried out to examine first, the validity of a new dietary assessment method, a handheld personal digital assistant with camera and mobile phone card (Wellnavi), in comparison with a weighed diet record as a reference method and second, the relation between obesity and underreporting in the Wellnavi method in 27 men and 48 women volunteers aged 30-67 y from the general population. On the validity, there were significant correlations (0.32-0.75) between the daily nutrient intakes measured by the Wellnavi method and the weighed diet record method in all the subjects except for some nutrients such as iron, magnesium and vitamin E. Results similar to those from the group of all the subjects were obtained in the men's group and the women's group. In all the subjects and the men's group and the women's group, the differences in the daily nutrient intakes between the two dietary assessment methods were statistically significant. However, good agreement of the differences between the two dietary assessment methods for many daily nutrient intakes was obtained in the nonobese men. The nutrient intakes estimated by the Wellnavi method in all the subjects and the men's group and the women's group were significantly lower than those values estimated by the weighed diet record method except for some nutrients such as sodium, iron and fat-soluble vitamins. With respect to the relation between obesity and underreporting, the obesity in women was not a factor of underreporting in the Wellnavi method, but the presence of this relation was undeniable in the obese men. The reason why the values of daily nutrient intakes in the Wellnavi method were lower than those estimated by the weighed diet record method seemed to be the low quality of the digital photo of the Wellnavi instrument. By improving the digital photo quality of this instrument, the Wellnavi method could become a useful new dietary assessment method to get accurate dietary information from people of a wide range of age and occupation, and a wide variety of physical situations of subjects from the general population.

View full abstract

To investigate the influence of fat-feeding dams on the food choice of their pups after weaning, each of three groups of dams was fed a low-fat diet (LHD), a high-fat diet (HFD) or a two-choice diet of LFD and HFD during pregnancy and lactation. Immediately after weaning, all pups were placed on a two-choice diet program for 5 wk. The fat energy ratio (F ratio) for dams fed the two-choice diet was 31%. Although no significant differences in body weight or calorie intake were observed between these three groups of dams, liver and perirenal fat tissue weights and plasma and liver trigluceride and total-cholesterol concentrations were lower in dams fed the two-choice diet than in dams fed LHD or HFD. Both groups of pups nursed by dams fed LFD or HFD continued to eat a large amount of HFD after weaning (F ratio was over 40%). Although within first week after weaning, no significant difference in the ratio of HFD intake was observed among the three groups of pups, the ratio for pups nursed by dams fed the two-choice diet decreased after the second week. The F ratio for pups nursed by dams fed the two-choice diet was 32%. These data lead us to conclude that if dams ate more than one diet in an adequate PFC ratio, their pups would have the ability to eat adequately after weaning.

View full abstract

We investigated whether capsaicin ingestion (150 mg) enhances substrate oxidation associated with thermogenic sympathetic activity as an energy metabolic modulator without causing prolongation of the cardiac QT interval during aerobic exercise in humans. Ten healthy males [24.4 (4.3) y] volunteered for this study. The cardiac autonomic nervous activities evaluated by means of heart rate variability of power spectral analysis, energy metabolism, and ECG QT interval were continuously measured during 5-min rest and 30-min exercise at 50% of maximal ventilatory threshold (50%VTmax) on a stationary ergometer with placebo or capsaicin oral administration chosen at random. The results indicated that there were no significant differences in heart rate during rest or exercise between the two trials. Autonomic nervous activity increased in the capsaicin tablet trial during exercise, but the difference did not reach statistical significance. Capsaicin, however, significantly induced a lower respiratory gas exchange ratio [0.92 (0.02) vs. 0.94 (0.02), means (SE), p<0.05] and higher fat oxidation [0.17 (0.04) vs. 0.12 (0.04) g/min, means (SE), p<0.05] during exercise. On the other hand, the data on the cardiac QT interval showed no significant difference, indicating that oral administration of capsaicin did not cause any adverse effect on cardiac depolarization-repolarization. In conclusion, it may be considered that capsaicin consumption 1 h before low intensity exercise (50%VTmax) is a valuable supplement for the treatment of individuals with hyperlipidemia and/or obesity because it improves lipolysis without any adverse effects on the cardiac depolarization and repolarization process.

View full abstract

Angelica keiskei (Ashitaba) is a perennial plant belonging to the Umbelliferae family. Recently, much attention has been focused on Ashitaba products as a so-called health food for the breakdown of cellulite among various physiological benefits of Ashitaba. The current study was carried out to investigate the physiological efficacy of dietary Ashitaba on serum and liver lipid profiles and body fat accumulation in rats. Rats were fed a high-fat diet with various amounts of Ashitaba for 28 d. Perirenal adipose tissue weights of rats fed the ×10 (170 mg/100 g BW) Ashitaba diet were significantly higher (p<0.05) than those of the control group. Serum triacylglycerol concentrations of rats fed the ×100 (1,700 mg/100 g BW) Ashitaba diet were significantly higher (p<0.05) than those of the ×1 (17 mg/100 g BW) group. Fecal weights and bile acid excretions of rats fed the ×10 or ×100 Ashitaba diet were significantly higher (p<0.05) than those of the control group. However, there were no significant differences in the body weight gain, epididymal adipose tissue weight, serum cholesterol or liver lipid concentrations or other biochemical profiles in the serum. Furthermore, even the excessive ingestion of Ashitaba had no significant pathological impact on the liver or kidney. These results indicate that the large intake of Ashitaba products may supply dietary fiber and thus improve gastrointestinal condition through the increased excretion of feces containing high level of bile acids, although even excessive intake of Ashitaba for a short period of 28 d did not show any impact on the decrease in body fat or modification of lipid profiles in this study.

View full abstract

The purpose of this study was to clarify the effects of nutrients on the gonadal development of male rats kept under constant darkness as a model of disturbed daily rhythm. The present study examined protein and vitamins, and their interactions. This study was based on three-way ANOVA; the three factors were lighting conditions, dietary protein and dietary vitamins, respectively. The levels of dietary protein were low or normal: 9% casein or 20% casein. The levels of dietary vitamins were low, normal or high: 1/3.3 of normal (AIN-93G diet) content, normal content, or three times the normal content, respectively. Other compositions were the same as those of the AIN-93G diet, and six kinds of experimental diet were prepared. Four-week-old rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle) for 4 wk. After 4 wk, the gonadal weights and serum testosterone content were evaluated. In the constant darkness groups (D-groups), the low-protein diet induced reduction of gonadal organ weights and serum testosterone concentrations. This reduction of gonadal organ weights was exacerbated by progressively higher levels of dietary vitamins. In the case of a normal-protein diet, the depression of gonadal development was not accelerated by high-vitamin intake. In the normal lighting groups (N-groups), the low-protein and high-vitamin diet slightly depressed gonadal development. These results suggest that the metabolism of protein and vitamins is different in rats being kept under constant darkness, and that excess dietary vitamins have an adverse effect on gonadal development in rats fed a low-protein diet.

View full abstract

The purpose of this study was to investigate whether combined capsaicin, green tea, and chicken essence tablets (CCGC) enhance human autonomic nervous activities (ANS) associated with thermogenic sympathetic activity without any adverse effect on the cardiac depolarization-repolarization period. Six healthy males (25.2±1.7 y) volunteered for this experiment. Autonomic nervous activities were examined 5-min at rest per 30-min for total 1.5 h after consuming chicken or CCGC or placebo tablets at random on separate days. Using heart rate variability power spectral analysis, we assessed human autonomic nervous activities. In comparison to chicken essence or placebo tablets, it was observed that the consumption of CCGC significantly increased human autonomic nervous activities [Total power representing over-all ANS activity; CCGC trial 160.2 (50.0) vs. placebo 92.8 (53.3)%, p<0.05; VLF, very low-frequency power associated with thermogenic sympathetic activity: CCGC trial 235.5 (101.7) vs. chicken 130.5 (52.9)%, p<0.05; LF, low frequency power representing combined sympatho-vagal activity: CCGC trial 199.8 (59.8) vs. placebo 120.6 (49.2)%, p<0.05] at 60-min and 90-min. There were no significant differences in heart rate corrected cardiac recovery time (RTc) or QT interval (QTc). In conclusion, the consumption of CCGC enhances thermogenic sympathetic activity compared to that of chicken essence or placebo tablets. Therefore, these results suggest that combined capsaicin, green tea, and chicken essence tablets may be a beneficial food ingredient improving human autonomic nervous activities, particularly thermogenic sympathetic activity as a modulator of energy metabolism without any adverse effects on cardiac electrical stability.

View full abstract

Nutrition may play an important role in the pathogenesis and treatment of ulcerative colitis. Several studies suggest an association between dietary factors and the onset of ulcerative colitis; however, only few studies have examined the relationship between dietary intake and relapse of ulcerative colitis. The aim of this study was to assess the dietary intake and antioxidative capacity of ulcerative colitis patients and to elucidate the efficacy of dietary therapy for ulcerative colitis. Dietary intake, fatty acid composition of phospholipids in plasma and neutrophils, serum fat-soluble vitamin levels, and oxygen radical absorbance capacity were analyzed in 29 ulcerative colitis patients (7 males and 22 females), who were treated at the Department of Gastroenterology, Okayama University Hospital. Total fat intake, fat energy ratio and linoleic acid intake were significantly lower, while protein and carbohydrate intakes were significantly higher, in the patients than age- and sex-matched controls. In the neutrophil phospholipids of ulcerative colitis patients, significantly higher levels of linoleic aicd and arachidonic acid and a lower level of eicosapentaenoic acid were observed. The concentrations of serum retinol and β-carotene but not α-tocopherol were significantly lower and serum oxygen radical absorbance capacity was also lower than in the controls. Significant correlations between serum oxygen radical absorbance capacity and retinol (r=0.567, p=0.0031), α-tocopherol (r=0.560, p=0.0036) and β-carotene (r=0.440, p=0.0279) concentrations were observed in the ulcerative colitis patients. A diet restricting the intake of linoleic acid and supplemented with eicosapentaenoic acid and antioxidative vitamins may be recommendable for the nutritional management of ulcerative colitis patients.

View full abstract

D-Galactosamine (D-Galn: 300 mg/kg) was intraperitoneally administered to rats. After 6 h the activity of plasma GOT and GPT was significantly higher than that of the control group and plasma GOT and GPT activities increased thereafter. These results indicated that the necrotic process was initiated at about 6 h and developed thereafter. With co-administration of DMSO (1 h before administration of D-Galn: 2.5 mL/kg, oral), plasma GOT and GPT were significantly lower, showing that DMSO inhibited the necrotic action of D-Galn. After 6-24 h of D-Galn administration, the hepatic level of vitamin C, the most sensitive indicator of oxidative stress, decreased significantly, indicating that oxidative stress was significantly enhanced 6 h after D-Galn intoxication and thereafter. DMSO significantly restored the liver vitamin C level 24 h after D-Galn injection, demonstrating that DMSO effectively ameliorated the oxidative stress caused by D-Galn, resulting in the prevention of necrosis of the liver. Phosphorylated JNK and phospho-ERK were significantly increased transiently 6-12 h after treatment with D-Galn. These results indicated that oxidative stress and the activation of JNK took place almost simultaneously. Phosphorylated p38 MAPK was not changed and DMSO treatment did not affect the change of these MAPKs by D-Galn.

View full abstract

Nerium indicum is an India-Pakistan-originated shrub belonging to the oleander family. The ingestion of leaves of N. indicum before a meal is known to effect the lowering of postprandial glucose levels in Type II diabetic patients and this plant is now used as a folk remedy for Type II diabetes in some regions of Pakistan. In the present study, the hot-water extract of N. indicum leaves was found to reduce the postprandial rise in the blood glucose when maltose or sucrose was loaded in rats. It was also found that the extract strongly inhibited α-glucosidase, suggesting that the suppression of the postprandial rise in the blood glucose is due to the occurrence of some inhibitors of α-glucosidase in the leaves. We, therefore, tried to isolate the active principles from the leaf extract, using α-glucosidase-inhibitory activity as the index. Employing Sephadex G-15, silica gel and reversed-phase HPLC, we isolated two active compounds. The UV, mass and NMR spectrometric analyses established that the chemical structures of these compounds are 3-O-caffeoylquinic acid (chlorogenic acid) and its structural isomer, 5-O-caffeoylquinic acid. Both compounds were shown to inhibit α-glucosidases in a non-competitive manner. The authentic chlorogenic acid was found to suppress the postprandial rise in the blood glucose in rats and also inhibited the absorption of the glucose moiety from maltose and glucose in the everted gut sac system prepared from rat intestine. These results demonstrate that chlorogenic acid is one of the major anti-hyperglycemic principles present in the leaves of N. indicum. Furthermore, among polyphenol compounds tested, quercetin and catechins were shown to have strong inhibitory activity against α-glucosidase.

View full abstract

Following consecutive 12-wk administration of tablets containing 0, 200 or 400 mg grape seed extract (calculated as proanthocyanidin) to 61 healthy subjects with LDL cholesterol (LDL-C) levels of 100 to 180 mg/dL, effects of such treatment compared to administration of placebo tablets on malondialdehyde-modified LDL (MDA-LDL), representing one oxidized type of LDL, were investigated by a single blind method. MDA-LDL level in the 200 mg (calculated as proanthocyanidin) group was significantly (p=0.008) reduced compared to the basal level, 12 wk after the start of administration. In the 400 mg (calculated as proanthocyanidin) group, a significant decrease in MDA-LDL level compared to the basal level was found 6 and 12 wk after the start of administration (6 wk: p=0.015, 12 wk: p=0.009). Subjects with high levels of MDA-LDL/ApoB (MDA-LDL/ApoB≥100 mU/mL) in the 200 mg group showed significantly (p=0.011) reduced MDA-LDL levels at 12 wk after the start of administration. In the 400 mg group, significant decreases in MDA-LDL level compared to the basal level were seen 6 and 12 wk after the start of administration (6 wk: p=0.001, 12 wk: p<0.001); and at week 6, significantly (p=0.048) lower values were observed compared to those in patients who took placebo tablets (0 mg proanthocyanidin). In subjects demonstrating the least body weight changes during the test period (less than±1.0 kg) in the 400 mg group, there was an increasing trend (p=0.088) in adiponectin levels 12 wk after the start of treatment. These results suggested that tablets containing grape seed extract exerted reducing effects on oxidized LDL, and might be useful in preventing lifestyle-related diseases such as arteriosclerosis.

View full abstract

Vitamin B₁₂ content (98.8±5.6 μg/100 g dry weight) of an edible cyanobacterium, Nostoc commune (Ishikurage) was determined by the Lactobacillus delbrueckii ATCC 7830 microbiological method. Bioautography with vitamin B₁₂-dependent Escherichia coli 215 indicated that N. commune contained two (main and minor) corrinoid-compounds. These corrinoid-compounds were purified to homogeneity from the dried algal cells and characterized. The main and minor purified corrinoid-compounds were identified as pseudovitamin B₁₂ and vitamin B₁₂, respectively, on the basis of silica gel 60 TLC, C18 reversed-phase HPLC, ¹H NMR spectroscopy, and UV-visible spectroscopy. These results suggest that the bacterial cells are not suitable for use as a vitamin B₁₂ source, especially in vegetarians.

View full abstract

Coenzyme Q₁₀ (CoQ₁₀) is a lipid-soluble antioxidant and essential component of the mitochondrial electron transfer system in the body, and is in wide use as a functional food material and cosmetic raw material. However, as CoQ₁₀ is extremely lipid-soluble, absorption by the body is not easy. In general, people use soft-gel capsules in which CoQ₁₀ is suspended in oil, and take these capsules with food. PureSorb-Q^TM40 (P40) was developed to improve CoQ₁₀ processability and absorption when taken without food, and the present study compared the effects of food on absorption between P40 and conventional lipid-soluble CoQ₁₀ in rats and humans. The results of a rat study showed higher uptake when P40 was administered in the fasting state or with food compared to lipid-soluble CoQ₁₀. The results of a human study showed that uptake was favorable when P40 was administered in the fasting state, and even when administered postprandially, a significant difference was noted in uptake rate up to 6 h after intake and uptake volume up to 8 h after intake when compared to lipid-soluble CoQ₁₀. These results show that any CoQ₁₀ product using P40 can be quickly and reliably absorbed by the body regardless of dosage form or intake time.

View full abstract