Mechanisms of riboflavin oversynthesis in a high flavinogenic mold, Eremothecium ashbyii, were examined in relation to growth, riboflavin formation and related synthases, and medium pH with increasing culture periods. Growth reached maximum at 1 d and then decreased, riboflavin formation proceeded rapidly up to 5 d and approached almost a plateau region. The medium pH reached minimum at 1 d and thereafter fairly rapidly increased until 3 d, then gradually increased to 7 d after cultivation. The crude enzyme solution from the mycelia at specified culture periods was run through a column of Sephadex G-200, indicating two riboflavin synthase activities on the chromatogram. The fluctuation of the growth and the specific activities of the two enzymes were examined with increasing culture periods, which showed that the heavy enzyme may be a constitutive one and that the light enzyme may be concerned with the oversynthesis of riboflavin in E. ashbyii. The heavy enzyme was then purified by 49-fold after dialysis of the ammonium sulfate precipitate by a series of column chromatographies with Sephadex G-200, hydroxyapatite, DEAF-Sepharose A-50 and DEAE-cellulose. The purified enzyme which was treated with weak alkaline solution was broken into the light enzyme, showing two bands on an acrylamide disc gel electrophoresis. The relation of the heavy and the light enzymes to the oversynthesis of riboflavin in E, ashbyii was discussed.
We examined the inhibitory effects of aqueous ethanol extract from mulberry leaves (ME) on postprandial hyperglycemia in normal Wistar rats. ME dose-dependently suppressed the postprandial rise of blood glucose in rats, when ME (0.02-0.5g/kg) was given 0.5h before the administration of carbohydrates such as sucrose, maltose and starch. The ME dose showing 50% inhibition of the increment of blood glucose (ED50) was 0.11g/kg for sucrose, 0.44g/kg for maltose, and 0.38g/kg for starch. ME and its basic fraction (MB) containing 1-deoxynojirimycin were assayed for their inhibitory effects (IC50) on disaccharidase derived from the small intestine of rats. The IC50 value of ME was 3.2μg/mL for sucrase, 10μg/mL for isomaltase, and 51μg/mL for maltase. The IC50 value of MB was 0.36μg/mL for sucrase, 1.1μg/mL for isomaltase, and 6.2μg/mL for maltase. The IC50 value of 1-deoxynojirimycin as the principle component in ME was 0.015μg/mL for sucrase and 0.21μg/ mL for maltase, and this value was comparable to the IC50 of voglibose. The inhibitory activity of ME in α-amylase was weak. These results suggest that ME strongly suppresses postprandial hyperglycemia after carbohydrate loading by inhibiting the activity of disaccharidases in the small intestine of rats.
Although it is now generally acknowledged in Western countries that mismeasurement (under-and overestimation) of dietary intake is a serious problem in studies on diet and health, the validity of dietary assessment methods in Japan has seldom been externally evaluated with objective measures. This study used the Goldberg cut-off to examine whether the energy intake in Japan could be regarded as a measure of habitual energy intake at the group level. Examined here were six published dietary studies in Japan providing 14 subgroups when divided by sex and dietary assessment method. Reported energy intake was expressed as a multiple of basal metabolic rate estimated using equations (EI/ BMR). EI/BMR was compared with the subgroup-specific cut-off values representing the lowest and highest values of EI/BMR that could reflect the habitual energy expenditure. Mean EI/BMR was 1.49 (SD=0.09), which was lower than an expected requirement of 1.55. When all 14 subgroups were combined, seven subgroups (50%) had an EI/BMR less than the subgroup-specific lower cut-off value, and one (7%) had the ratio greater than the upper value. The percentages of subgroups having the ratio less than the lower value and greater than the upper value ranged from 43 to 57% and from 0 to 14%, respectively, when subgroups of women (n=8), men (n=6), diet record (n=7), and questionnaire method (n=7) were evaluated separately. These findings suggest that responsible investigators in Japan should critically examine dietary intake data in any study of diet and health.
This study was designed to show the effect of boiling on the antihypertensive and antioxidant activities of onion in NG-nitro-L-arginine methyl ester (L-NAME) inducedhypertensive rats and spontaneously hypertensive rats (SHR). Male 6-wk-old Sprague-Dawley rats were made hypertensive by being given distilled water containing L-NAME at a dose of 50mg/kg BW/d. These rats were fed diets containing raw or boiled onion at a concentration of 5%. Raw onion significantly reduced the increase in systolic blood pressure in both LNAME induced-hypertensive rats and SHR, and inhibited the increase in thiobarbituric acidreactive substances (TBARS) and conjugated dienes in the plasma and tissues of SHR. The antihypertensive effect of boiled onion was not found, and the antioxidant activity of it was much weaker than that of raw onion. The excretion of nitric oxide metabolites (NOx) in urine was enhanced by raw onion in both L-NAME induced-hypertensive rats and SHR, and was enhanced by boiled onion only in SHR. In conclusion, our results suggested that the antihypertensive activity of onion disappeared during boiling, and the disappear of the antihypertensive activity of raw onion after boiling might come, in part, from a decrease of the antioxidative activity of onion, with a consequent reduction in the saving of nitric oxide (NO).
Shirasuboshi (boiled and semi-dried whitebait) is a processed fish food that contains abundant calcium. It is eaten whole and commonly consumed in Japan. In this study, the effect of sudachi (Citrus sudachi) juice on calcium, magnesium and phosphorus bioavailability, and bone metabolism in rats was examined. After 14 d of diets low in calcium and phosphorus, male Sprague-Dawley rats were fed shirasuboshi diets containing dried shirasuboshi powder treated with 20% (S20) or 40% (S40) sudachi juice, or distilled water (C) (0.5% Ca; 0.3% P) for 14 d. The apparent absorptions and retentions of calcium, magnesium and phosphorus from shirasuboshi were determined. Bone formation was calculated by measuring serum osteocalcin, and bone resorption by measuring urinary pyridinoline and deoxypyridinoline. The apparent absorption and retention of calcium and magnesium in the S20 group were significantly higher than in the C and S40 groups. Although serum osteocalcin was not affected by the addition of sudachi juice, the urinary pyridinoline and deoxypyridinoline concentrations in the S40 group were significantly lower than in the C and S20 groups. Our results indicate that sudachi juice added to shirasuboshi was associated with increased calcium bioavailability and suppressed bone resorption in rats.
The purpose of this study was to obtain detailed data on the dietary intake of energy, macronutrients, and micronutrients, especially minerals and vitamins, of healthy free-living people over the age of 70 in Japan and to clarify the correlations among nutrient intakes. The survey was conducted in November 2001 for 5 7 persons (men: 31, women: 26) aged 74 y (born in 1927) living in Niigata City, Japan. A precise weighing method was used to record food intake for three consecutive days. Nutrient intake was calculated based on the Standard Tables of Food Composition in Japan (5th ed.). The intakes of energy and total protein were 44.8±7.7 kcal/kg/d and 1.80±0.35g/kg/d for men and 38.1±7.6 kcal/ kg/d and 1.51±0.26g/kg/d for women. These valuess are significantly higher than those proposed by the current Recommended Dietary Allowances (RDAs) and the data by the 2001 National Nutrition Survey in Japan. The energy intake ratios from protein, carbohydrate and fat for men were 16 : 58 : 22, respectively, and the residual part was alcohol. For women, the ratios were 16 : 62 : 22. The proportion of total protein intake that consisted of animal protein was 57.8% for men and 52.8% for women. For both sexes, all of the mean daily intakes of nine minerals and 12 vitamins were higher than those prescribed for elderly Japanese people (≥70 y) in the RDAs. Significant strong correlations were found between total protein intake and intakes of vitamins D, B2 and B6, as well as niacin and pantothenic acid (p<0.0001). Among the nine minerals, the correlations were very strong between potassium and magnesium, calcium and phosphorus, magnesium and iron, magnesium and copper, iron and copper, and zinc and copper (r's>0.700). For vitamins, strong correlations were found between vitamin A and folic acid, vitamin B2 and pantothenic acid, and folic acid and pantothenic acid. Furthermore, strong relationships were observed between potassium and folic acid, potassium and pantothenic acid, potassium and dietary fiber, phosphorus and vitamin B2, phosphorus and pantothenic acid, iron and folic acid, zinc and vitamin B12, and copper and vitamin B12. From these results, it is evident that age is not an important determinant of dietary intake among apparently healthy elderly Japanese people aged 74 y. In addition, the high intake of energy and protein in the Japanese dietary pattern, based upon high consumption of fish and/or shellfish, vegetables, and fruits, provide sufficient minerals and vitamins.
Beta-cryptoxanthin (β-CRX) is a carotenoid pigment found in Satsuma mandarin (Citrus unshiu Marc.) fruit, which is heavily produced in Japan. In this study, we evaluated the seasonal changes in the serum β-CRX level and investigated predictors of serum β-CRX level by multiple linear regression analysis. Blood tests and self-administered questionnaires were used every other month for one year. The subjects were healthy volunteers, 15 males and 12 females. The serum β-CRX levels increased dramatically as the intake of Satsuma mandarin increased; the maximum increase was noted in January. Multiple linear regression analysis showed that, in males, the serum β-CRX level could be predicted by Satsuma mandarin intake, age and the month of blood sampling; however, it was inversely associated with alcohol and smoking habits. Conversely, in females, the serum β-CRX concentration could be predicted by Satsuma mandarin intake, the month of blood sampling and age; however, it was inversely associated with body mass index. The results of multiple linear regression analysis suggest that the serum β-CRX levels can be used to evaluate the intake volume of Satsuma mandarin. Furthermore, β-CRX is a useful biomarker to estimate the beneficial effects of Satsuma mandarin intake in epidemiological studies.
Oxidized low-density lipoprotein (LDL) is considered a risk factor in atherosclerosis, and polyphenols are the potential agents to inhibit the oxidation of LDL. We determined the polyphenol contents and the antioxidant activities of commonly consumed vegetables in Vietnam and assessed the quantity of the polyphenol intake from vegetables in the current Vietnamese diet. The polyphenol contents in 30 kinds of vegetables was determined by the Folin-Ciocalteu method. The antioxidant activities of vegetables were evaluated by measuring the oxidation of LDL and the reduction of the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. In this study, some herbs and edible wild vegetables possessed high contents of polyphenols and antioxidant activities. Among green vegetables, sweet potato leaves showed both a high polyphenol content and antioxidant activity. The mean polyphenol daily intake of the Vietnamese was a 595mg catechin equivalent. Water spinach, a kind of green vegetable, contributed the highest amount (45%) of the total polyphenol intake, followed by other green vegetables. Neither herbs nor edible wild vegetables contributed significantly to the total polyphenol intake due to their low consumption. Green vegetables are therefore considered very important sources of polyphenol intake for the Vietnamese.
Although hesperidin lowers serum total cholesterol (TC) or triglyceride (TG) in animal models, its effect in humans remains unclear. Using a soluble hesperidin derivative, glucosyl hesperidin (G-hesperidin), as a hesperidin source, we examined the efficacy on hyperlipidemic subjects. G-Hesperidin was administered to the subjects at 100 or 500mg/d for 6 wk. The percentage of subjects who had a change in serum cholesterol levels was less than 20%. However, 45-55% of the total subjects showed a reduction in serum TG level. The subjects were classified into normal (TC<230mg/dL, TG<150mg/dL), high-TC (TC>230mg/dL, TG<150mg/dL) and high-TG (TG>150mg/dL) types. While serum cholesterol levels scarcely changed in any phenotype, TG level was significantly reduced by administration in the high-TG type. In this phenotype, serum apolipoprotein (apo) C-II and E levels decreased by the administration, but non-apo B. G-Hesperidin also raised low-density lipoprotein (.LDL)-cholesterollapo B in the high-TG type. These results indicate that Ghesperidin preferentially lowers serum TG in hypertriglyceridemic subjects and that this effect is possibly caused by the facilitation of catabolism of TG-rich lipoproteins and may contribute to the reduction of small dense LDL.
All-trans retinoic acid (ATRA) is used as differentiation therapy for acute promyelocytic leukemia (APL). The two major adverse effects of ATRA therapy are hyperleukocytosis and retinoic acid syndrome. In order to prevent these adverse effects, low-dose ATRA therapy (25mg/m2/d) has been tried in adults. Accordingly we assessed the pharmacokinetics of low-dose ATRA in children with cancer. Four children (one with APL and three with other advanced cancer) were administered ATRA and its pharmacokinetics were evaluated. In three patients, the pharmacokinetic parameters of ATRA were similar to those previously determined for APL patients in remission, but the values were lower in one patient. Low-dose ATRA was effective for APL, but not for the solid tumors. This therapy did not cause any severe toxicity. Further studies are needed to determine the optimum ATRA regimen and to evaluate low-dose ATRA combined with chemotherapy in children with APL.
The effects of dietary fish oil (FO) on serum lipid levels and tumor proliferation were studied in Donryu rats subcutaneously implanted with the ascites hepatoma cell line AH109A. Solid tumor weight was significantly less and serum total cholesterol (T-Ch) level significantly lower in the groups fed the FO diet both before and after AH109A implantation than in the groups fed the corn oil diet. There were no significant effects in the serum lipid levels and tumor proliferation in the groups fed the FO diet only before or after the hepatoma implantation. The serum triacylglyceride, phospholipid, nonesterified fatty acid, T-Ch, and very-low-density lipoprotein+low-density lipoprotein-Ch levels showed significant positive correlations with the solid tumor weight. These results suggest that dietary FO ingestion after hepatoma implantation suppresses tumor proliferation and reduces serum lipid levels along with suppressing tumor proliferation.
A diet containing adequate amounts of protein rapidly suppresses myofibrillar protein degradation after refeeding in young rats and mice. However, it is unclear whether this suppression is seen in adult animals. This study was undertaken to compare dietary protein-induced suppression of myofibrillar protein degradation in young and adult mice. Reductions in rates of myofibrillar protein degradation measured by NT-methylhistidine (MeHis) released from the isolated extensor digitorum longus muscle were found at 4 to 7h after refeeding in both young (7-wk-old) and adult (8-mo-old) mice, indicating that the response time of feeding-induced suppression of myofibrillar protein degradation was the same. When young (8-wk-old) mice were fed a 20% casein diet (20C) for 1 h after 18h starvation, the rate of myofibrillar protein degradation was significantly decreased at 4 h after refeeding; however, mice fed a 10% casein diet (10C), 5% casein diet (5C), or protein-free diet (0C) did not show suppression of myofibrillar protein degradation. Adult (8-mo-old) mice fed 20C or 10C showed a reduction in the rate of MeHis release. The plasma concentration of leucine in young mice was only higher when they were fed 20C. Adult mice fed 20C or 10C showed higher plasma concentrations of leucine. These results suggest that postprandial suppression of myofibrillar protein degradation occurs in adult mice as in young mice, but the adult mice respond to a lower amount of dietary casein compared to the young mice.