Kyoden Yasumoto

Supplementation with chromium picolinate recovers renal Cr concentration and improves carbohydrate metabolism and renal function in type 2 diabetic mice

To study the preventive effect of supplemented chromium picolinate (CrPic) on the development of diabetic nephropathy in mice, we analyzed the effects of CrPic supplementation on renal function and concentrations of serum glucose and tissue chromium (Cr). In experiment 1, male KK-Ay obese diabetic mice were fed either a control diet (control) or a diet supplemented with 2 mg/kg diet (Cr2) or 10 mg/kg diet (Cr10) of Cr for 12 wk. Cr10 significantly ameliorated hyperglycemia after a glucose load, creatinine clearance rates, and urinary microalbumin levels (p<0.05). In experiment 2, the Cr10 diet was fed to male KK-Ay obese diabetic mice and C57BL nondiabetic mice for 4 wk. The CrPic diet reduced urinary albumin excretion in the diabetic mice (p<0.05). Inductively coupled plasma-mass spectrometry analysis revealed that the renal Cr content and the recovery of renal Cr concentration after Cr supplementation were significantly lower in the diabetic mice than in the nondiabetic mice (p<0.01). These observations suggest that Cr supplementation of type 2 diabetic mice reduces the symptoms of hyperglycemia and improves the renal function by recovering renal Cr concentration.

Product specificity of rice germ lipoxygenase

Incubation of linoleic acid with partially purified lipoxygenase from rice germ yielded a ratio of 9-to 13-hydroperoxides of linoleic acid of 97∶3 as measured by high performance liquid chromatography. Under similar conditions, hematin gave the 9- to 13-hydroperoxides at a ratio of 51∶49, and soybean lipoxygenase-a at 9∶91. Infrared spectral analysis revealedcis-trans configuration to predominate in the reaction products with the rice germ enzyme as was with the soybean enzyme.

Dietary butylated hydroxytoluene counteracts with paraquat to reduce the rate of hepatic DNA single strand breaks in senescence-accelerated mice.

The present study was designed to assess the age-related changes of DNA single strand breaks (SSB) in the liver of senescence-resistant and senescence-prone mice, SAMR1/Fky and SAMP1@Fky. In the first series of experiments, the animals were fed a commercial diet for 12-18 months. The mice were killed and the livers were excised at 3- or 6-month intervals for the analysis of the rate of DNA SSB by the ethidium bromide fluorescence method. With advancing age, the rate of DNA SSB was increased in both strains of mice but the increase was significantly higher in SAMP1@Fky than in SAMR1/Fky. In the second series of experiments, the mice were fed one of the following diets for 12 weeks: 20% casein diet (basal diet), basal diet with 300 ppm butylated hydroxytoluene (BHT) added, basal diet with 200 ppm paraquat (PQ) added, and basal diet with 200 ppm PQ plus 300 ppm BHT added. Added dietary PQ increased the rate of DNA SSB in both SAMP1@Fky and SAMR1/Fky. The increases were offset by co-administration of BHT. Dietary BHT, therefore, may suppress the oxidative stress developed by paraquat administration.

Use of 13C-labeled glucose for measuring exogenous glucose oxidation in mice.

The author modified a respiratory gas analyzer to analyze the respiratory 13CO2 of 12 small laboratory animals all at once. To investigate the practical use of this system, mice were orally (OR) or intravenously (IV) given glucose solutions containing three different amounts of 13C-labeled glucose. Expired 13CO2 derived from exogenous glucose was detected within 10 minutes after administration in OR mice, but about 30 minutes in IV mice. The height of the peak of 13CO2 expiration was correlated with the administered 13C-glucose mass.

Selenium Content of Foods and Its Average Daily Intake in Japan

種々の食品のセレン含量を, 比色法また螢光法で測定した。魚, その他の海産物, およびニンニク中に著量のセレンが検出された。しかし, 問題となるほど過剰にセレンを含んだものはなかった。さらに, 将来の食糧源としての微生物菌体, 藻類中のセレン含量を測定したが, 全般に低い値であった。今回の分析結果, ならびに分析値および食糧需給調査資料をもとにして, 日本人が1人あたり1日に摂取するセレン量を求めたところ207.7μgであった。この摂取量はカナダ人, アメリカ人とほぼ等しく, 各国とも同等のセレン栄養の状態にあると推察された。

Selenium contents of rice grown at various sites in Japan

Abstract Sixty-nine brown rice ( Oryza sativa L. japonica ) samples, composed of 18 different cultivars, were collected from 37 sites in Japan, and their selenium contents were determined by a fluorometric method. The total mean ± standard deviation value for the 69 samples was 43 ± 27 ng Se/g. The selenium levels were found to vary by the site at which the rice was grown but not by cultivar. The average selenium intake by Japanese was calculated as 127,ug/day/capita based on the data obtained in this study and the food consumption pattern revealed in the annual nutrition survey conducted by the Ministry of Health and Welfare, Japan. Selenium intake from rice was estimated to account for only 5–10 μg/day/capita; rice is not a significant selenium source in the Japanese diet.

A New Sulfur-containing Peptide from Lentinus edodes Acting as a Precursor for Lenthionine

A sulfur-containing peptide, acting as an enzymatic precursor of the aroma-bearing substance, was isolated in crystalline form from fruiting bodies of the shiitake mushroom. The isolation procedure consists of methanol extraction, repeated ion-exchange chromatographies, and crystallization from methanol-water. The common name “lentinic acid” is given for the isolated peptide. Amino acid analysis, performed after acid hydrolysis of the oxidized or desulfurized peptide, indicates involvement of a glutamic acid and S-substituted cysteine sulfoxide in the molecule. Results of enzymatic assays led to the designation of l-configuration for the component amino acids. The presence of a γ-glutamyl peptide bond is shown, since glutamic acid constitutes the N-terminal amino acid and a free amino group is adjacent to a free carboxyl group. The structure proposed for lentinic acid is, The precise structure for the portion in brackets is unidentified.

Monitoring the irradiation-induced conformational changes of ovalbumin by using monoclonal antibodies and surface plasmon resonance.

Two types of conformationally specific anti-irradiated ovalbumin monoclonal antibodies were prepared in order to study and monitor irradiation-induced structural changes in the ovalbumin molecule. Surface plasmon resonance (SPR) detection was used to investigate the kinetic parameters of the reaction between antibodies and ovalbumin which had been administered with different doses of irradiation (0, 1.5, 2.0, 5.0, 10, 20, 50, and 100 kGy). The results demonstrate that the combination of monoclonal antibodies and the SPR method can be used to characterize the irradiation-induced conformational change with an unlabelled reagent.

Enzymic formation of thiamine pyrophosphate in plants.

Evidence was presented by paper chromatographic analysis on the occurrence of an enzyme capable of catalyzing a pyrophosphate transfer from ATP to thiamine in green leaves of various plants. The exclusive localization of the enzyme activity in the 105,000 X g supernatant (in a soluble form) was demonstrated by differential centrifugation of a cell homogentae in 0.25 M sucrose. The enzyme was purified by column chromatography with DEAE-cellulose and by gel filtration with Sephadex G-150. The partially pruified preparation, while contaminated with detectable activity of acid phosphatase, lost the ability of utilizing thiamine monophosphate as the substrate in place of thiamine. These findings lead to the conclusion that thiamine pyrophosphate is formed in green leaves of plants through a direct pyrophosphorylation of thiamine in the presence of ATP and Mg.

Amino Acid Composition of Soybean Protein Increased Postprandial Carbohydrate Oxidation in Diabetic Mice

The effects of an amino acid mixture simulating dietary soybean protein on the postprandial energy metabolism was investigated using type II diabetic mice. KK-Ay strain mice were fed restrictive isoenergetic and isonitrogenous diets (35% of energy as protein and 5% as fat) based on either casein, soybean protein isolate hydrolysate (SPI-H), SPI-HET (ethanol unsoluble fraction of SPI-H), SPI-AA and casein-AA (amino acid mixtures simulating SPI-H and casein). To measure dietary carbohydrate oxidation, the animals were fed a diet containing 13C-glucose. Postprandial respiratory quotient and expired 13CO2 were higher in the SPI-AA than in the casein-AA group, as the differences were similarly observed in mice fed SPI-H and casein diet. No significant differences were observed in the postprandial respiratory quotient and expired 13CO2 between the SPI-H and SPI-HET group. In conclusion, this study on food-restricted mice indicates that the amino acid mixtures simulating SPI-H or casein could affect postprandial energy metabolism in diabetic mice, as observed in those fed SPI-H or casein in the form of peptide or protein.