Spectrophotometrical analysis of pyridine nucleotide transglycosidase in mammalian tissues indicated that the enzyme activity was observed to be distributed ubiquitously among the mammalian tissues analyzed, although the velocity ratio of transglycosidation/hydrolysis (vT/vH) and the partitioning of nicotinic acid against water differed with the pyridine nucleotide substrate and the mammalian species, and also with the organ from which the enzyme was extracted. A clarification of their enzymatic properties reveals that pyridine nucleotide transglycosidases were purified from rabbit spleen and guinea pig spleen, after which a kinetic analysis of the transglycosidases was performed. The resulting values, including Km, maximal transglycosidation velocity, and vT/vH, indicated that the enzymes differ in their substrate specificities toward pyridine nucleotide and pyridine base structures.
Besides isonicotinic acid analogs of pyridine nucleotides, 24 novel pyridine nucleotide cofactors that have an amino acid residue at the carbonyl carbon of the nicotinamide moiety have been prepared by means of transglycosidation reactions catalyzed by rabbit spleen and guinea pig spleen pyridine nucleotide transglycosidases. Their chemical properties were characterized by means of proton NMR, Fab-mass, and UV spectral measurement and phosphodiesterase digestion. Except for the isonicotinic acid ones, these nicotinoylamino acid analogs were shown to function as substrates for both the hydrolysis and the transglycosidation reactions catalyzed by the mammalian NAD glycohydrolases, though their substrate activities were lower than those with the original pyridine nucleotides (NMN, NAD, and NADP). They were inactive in regard to yeast alcohol dehydrogenase-and Thermoanaerobium brockii alcohol dehydrogenase (NADP dependent)-oxidation.
This study was performed to examine the effects of several kinds of dietary fibers (DF) with different physical properties on dietary RNA metabolism. Male Wistar strain rats, 4 wk old, were fed diets with or without a 3% yeast RNA and a 5% DF (cellulose, chitin, chitosan, inulin, and xanthan gum) for 20 d (Experiment 1) or 5 d (Experiment 2). Feeding DF tested lowered the serum uric acid and allantoin concentrations and the urinary excretions of their compounds and increased the amount of RNA excreted into the feces compared with fiber-free. The water-holding capacity and nucleotide adsorption of chitin and chitosan in acidic solutions were higher than those of cellulose. The digestion rate of RNA by RNase A in vitro was found to be lower in the DF tested than in fiber-free. The decrease was remarkable in chitosan and xanthan gum. The uptakes of 14C-labeled adenosine and adenosine 5'-monophosphate (5'-AMP) in the rat jejunum were markedly decreased in regard to chitosan and xanthan gum in comparison with the fiber-free. These phenomena suggest that DF with high viscosity is more strongly associated with the suppression of RNA digestion by RNase A and the depression of the uptake of purine compounds to jejunum. The present results reveal that the elevation of serum uric acid concentration induced by dietary RNA can be suppressed by DF in rats.
Interrelationships between behavior and concentrations of serum amino acids in stressed rats with immobilization and water immersion were investigated. Rats were subjected to 7h of immobilization with water-immersion stress (IWS) in each sequential day, and serum amino acids were then determined. On the first day, serum taurine, threonine, valine, leucine, isoleucine, phenylalanine, lysine, and histidine (increased-type of amino acids) were significantly increased, but alanine (decreased-type) was significantly de-creased. On days 3 and 7, the increase was retained, except for threonine, histidine, and ly-sine. Spontaneous activities (locomotion, rearing behavior, hole-poking) under loading water-immersion stress were significantly decreased, but a supplementation of branchedchain amino acids (BCAA) led to recovery. We suggest that pretreatment with some kind of increased type of amino acid, such as BCAA, might effectively prevent decline in spontaneous activities evoked by water-immersion stress.
The National Nutrition Survey of Japan indicated a trend toward a decreasing body mass index (BIM, kg/m2) among young Japanese women. Current studies suggest that not-high BMI often does not correlate with not-high body fat percentage. Recently, the classification of BMI in adult Asians was proposed by the International Obesity Task Force. The addition of an “at risk of overweight” category, BMI as 23.0-249, was intended to prevent chronic diseases. We investigated the association between body fat percentage (BF%) andBMI to evaluate the screening performance of BMI focused on individual preventive medicine. The subjects consisted of 605 female college students, The subjects' ages (y), heights (cm), body weights (kg), BMIs, and BF percents with underwater weighing expressed as the means±SD were 19.6±0, 5, 158.7±5.6, 53.8±7.2, 21.3±2.4, and 24.9±4.9, respectively. We defined high BF% as ±85th percentile of BF% (29.8%). High-BF% individuals are often not classified into BMI≥23.0 because their BMI readings are very broad (18, 4-31.7). In comparison to the screening performances (specificity and sensitivity), BMI≥23.0(85.3% and 52.1%, respectively), rather than BMI≥25.0 (96.7% and 29.8%, respectively), is recommended for the mass evaluation of fatness. For this reason, the BMI “at risk of overweight” category is characterized as the threshold of increasing the appearance ratio of high-BF% individuals. In conclusion, the BMI≥25.0kg/m2 category is determined as high BF%, regardless of body composition measurement for mass evaluation as a result of quite high specificity. Even so, body composition measurement is necessitated by the individual evaluation of fatness focused on preventive medicine because BMI performed a poor representation of body composition, especially BMI≥25.0kg/m2 individuals.
Fermented soybeans (Natto), a traditional Japanese food, contain more than 100 times as much vitamin K2 as various cheeses and are considered to promote γ-carboxylation. Thus it is conceivable that Natto may play a preventive role in the development of osteoporosis. In this study, the relationships between the bone stiffness index measured by ultrasound, bone turnover markers, and lifestyle factors, including Natto intake, were examined in relation to vitamin D receptor (VDR) polymorphism. Among 117 premenopausal volunteers, approximately 75% were bb homozygotes, 20% were Bb heterozygotes, and only5% were BB homozygotes. The B allele group and the bb group were subdivided according to Natto intake. In a monovariate analysis, no significant differences in indices for dietary intake, including Ca and vitamin D intake, were observed. The stiffness index in the B allelegroup, however, was slightly lower than in the bb groups when there was no Natto intake. There were no significant differences in serum ALP and Gla-osteocalcin, bone formationmarkers, or NTx and Ca in urine, bone resorption markers. A logistic regression test, including the interactional effect of Natto intake and VDR RFLP, indicated that the B allele group was a risk factor of bone mineral loss and that Natto was effective in maintaining bone stiffness in this group. Although the present study was cross sectional and requires longitudinal investigation, Natto may improve the bone health of people who have a low affinity receptor for vitamin D.
The effect of an acute oral load of 2g ethanol/kg body weight was studied in a group of male and female 10-wk-old C3H/HeNCrj (C3H/He) mice to investigate gender change throughout differences of the hepatic ethanol metabolism of mice. The following parameters were measured in the serum from 0h to 3h after the start of the experiment; ethanol, acetaldehyde, and acetate. Their concentrations in the serum in female mice tended to show lower levels than in male mice. In female mice, the concentration of ethanol at 1h and the concentration of acetate at 1h, 2h, and 3h after ethanol administration showed significantly lower levels than in male mice. Ten-week-old male and female C3H/He mice were subcutaneously injected 50μg/kg body weight β-estradiol and 1.45mmol/kg body weight testosterone propionate (testosterone) in olive oil, respectively, and changes in the activity of enzymes related to the hepatic ethanol metabolism of mice were examined at 24h after the administration of sex hormones. The activity of the cytosolic alcohol dehydrogenase (ADH) and microsomal aniline hydroxylase (ANH) and the low Km, high Km and total aldehyde dehydrogenase (AIDH) activities in the mitochondrial, the cytosolic, and the microsomal fraction of the liver were higher. Moreover, the density of the band of CYP2E1 in the microsome in female mice was stronger than in male mice, and in the microsomal fraction of the liver, the total content of cytochrome P-450 (CYP) and ethoxyresorufin O-dealkylase (EROD) activity in male mice showed significantly higher values than in female mice. The density of the band of CYP2E1 and the three activities of AIDH in the hepatic mitochondrial fraction of male mice increased significantly under treatment with β-estradiol. The three activities of AlDH of the cytosolic fraction of the liver in female mice significantly decreased under treatment with testosterone. The present findings suggested that in C3H/He mice livers, the rate of ethanol metabolism is faster in females than in males, and the enzymes related to ethanol metabolism are controlled by testosterone or β-estradiol. It is suggested that ethanol and its metabolite disappear faster from the serum of female mice than from the serum of male mice because the activities of hepatic enzymes related to ethanol metabolism are higher in female mice than in male mice.
The effects of rice starch-isoflavone diet or potato starch-isoflavone diet onplasma concentration of isoflavones, plasma lipids, cecal enzyme activity, and intestinalmicroflora were studied. Male 15-wk-old mice were fed a rice-starch-based or potatostarch-based diet supplemented with isoflavones for 4 wk, and plasma samples, cecal contents, and feces were collected individually. Plasma equol concentration was significantlyhigher in the potato-isoflavone diet group than in the rice-isoflavone diet group, but no significant difference was observed in plasma daidzein or genistein concentrations. Plasmatotal cholesterol concentration was higher in the potato-isoflavone diet group, but no significant difference was observed in plasma triglyceride concentration, Both cecal β-glucuronidase and β-glucosidase activities were significantly higher in the rice-isoflavone diet group. The number of bifidobacteria was significantly higher in the potato-isoflavone dietgroup. These results indicate that different types of starches have different influences on plasma isoflavone and suggest that the influences might be through the change of host physiology and/or the metabolism and composition of intestinal microflora.
Rats fed a Zn-deficient diet show characteristic variations in feed intake. These variations were followed by means of a personal computer. The specific feed intake patterns in rats fed a zinc-deficient diet before and after supplementation with protein and several essential amino acids were determined. The high protein diet decreased the amplitude of feed intake under zinc deficiency, probably because of a decrease in sensitivity to the deficiency. Furthermore, the zinc-deficient diet was supplemented with essential amino acids, and of them L-threonine showed the most marked effect on the increased variability of feed intake.
Swimming is a non-weight-bearing exercise. Therefore it has the advantage of maintaining skeletal integrity in aged persons with weakened skeletal structures. Unlike other weight-bearing aerobic exercises, however, it does not appear to exert sufficient stimu-lus on bone-remodeling activities because the local load-bearing on bone tissues is mild. The purpose of this study was to investigate the effect of swimming on bone remodeling, espe-cially with the use of implanted pellets containing bone morphogenetic protein (BMP) and demineralized bone matrix during the initial stages of the differentiation of mesenchymal cells to cartilage cells. Six-week-old female rats were divided into the swimming group and a control, nonswimming group. Test animals were forced to swim in a water bath for 30min daily for 2 wk. After the swimming protocol, pellets were implanted and harvested. Messenger RNA isolated from pellets was quantified by means of a reverse transcription-polymerase chain reaction. The expression of RNAs for bone sialoprotein and BMP-6 in pel-lets from the swimming group was apparently enhanced at 7 d after implantation. These re-sults suggested that systemic hormonal and/or metabolic changes that promote cartilage formation might have occurred after swimming because the effect was observed after the swimming protocol had ended and the pellets were implanted at a non-weight-bearing site.
Summary High activity (about 50 mU⋅mg protein-1) of methylmalonyl-CoA mutase (82-95% apo-enzyme) was constantly found during the cell growth of a methanol-utilizing bacterium, Methylobacterium extorquens NR-1. The apo-enzyme was purified to homogeneity and characterized. The purified enzyme was colorless. An apparent Mr of M. extorquens NR-1 enzyme was calculated to be 150, 000±5, 000 by Superdex 200 HR gel filtration. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave two protein bands with an apparent Mr of 85, 000±2, 000 and 70, 000±2, 000, indicating that the M. extorquens NR-1 enzyme is composed of two nonidentical subunits. NH2-terminal amino acid sequences of the small and large subunits of M. extorquens NR-1 enzyme showed no significant homology to those of the enzyme from other species. Some enzymological properties of the M, extorquens NR-1 enzyme were studied.
The absorption of zinc (Zn) in the form of casein phosphopeptide (CPP) complex was compared with that of its chloride form in rats given a soybean protein-based diet. We prepared 67Zn complex with CPP (67Zn-CPP). Male rats were given a diet containing ZnCl2 in the preliminary period. After overnight food deprivation, they were fed a test meal labeled 67Zn-CPP or 67ZnCl2 (4gZn-free diet +0.12mg 67Zn) with 0.5mg Dysprosium (Dy) as a fecal marker. Feces were collected for 5d and analyzed for 67Zn isotopic enrichment and Dy concentration with an inductively coupled plasma mass spectrometer. Fecal Dy excretion closely paralleled that of 67Zn, and more than 89% of the administered Dy was recovered in the feces collected for 5d. Moreover, the Zn source did not affect the excretion pattern of 67Zn. Since Dy and 67Zn were almost excreted within 3 d after the administration, the apparent absorption of 67Zn was calculated from the pooled data for 3d. The source of Zn did not affect the apparent absorption of 67Zn. These results suggested that dietary Zn in the form of CPP complex did not show higher absorbability in rats.
An ingestion of tomato powder rich in lycopene was examined for its effect on mice with Parkinson's disease-like syndrome induced by 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). To assess the preventive effect of tomato against the MPTP-in-duced selective destruction of dopaminergic nigrostrie, we determined striatal dopamine (DA). A4-wk ingestion of the experimental diet containing 20% (w/w) lyophilized tomato powders before MPTP treatment prevented a decrease in the DA level. This suggests that the tomato ingestion might serve as a preventive against neurodegenerative diseases such as Parkinson's disease caused by MPTP and other environmental toxins.