It has already been reported that globin digest (GD) exerts a hypotriglyceridemic action in laboratory animals and humans. A tetrapeptide, Val-Val-Tyr-Pro, extracted from GD, has also been shown to be 7000-times more active than the parent GD. We studied the hypotriglyceridemic effect of GD in subjects with borderline hyperlipidemia. In normal subjects, 1g of GD showed sufficient hypotriglyceridemic action. When borderline hypertriglyceridemic subjects were administered 1g of GD as a beverage with 40g of fat, the increases in serum and chylomicron (CM) TGs at 1-5h after the administration were suppressed to 25-50% of the control values (without GD). The areas under the serum TG and CM-TG concentration curves (AUCs; 0-6h) were significantly decreased to about 40% of the control, respectively. GD enhanced the elimination rate constants of TG and CM-TG in borderline hypertriglyceridemic subjects, and showed a more effective hypotriglyceridemic action than in normal subjects. GD thus appears to be useful for prevention of cardiovascular disease and atherosclerosis in subjects with borderline hypertriglyceridemia.

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The gonads of sea cucumber dried in the sun are prized as a tasty, expensive delicacy known as “konoko.” To account for the pleasant taste, we analyzed the proximate composition and extractable components of raw gonads (A) and konoko (B), comparing the results between the two, and also with reported analytical data for corresponding marine products. Although the flavor and texture of A were markedly changed by sun-drying, analytical values indicated little modification except for water content. Crude ash was more abundant and the protein content was lower in A than in other marine gonads. The extracts of both A and B contained large amounts of free amino acids, among which Glu was enormously high, followed by a relatively large amount of Ala and Gly; a fairly large amount of AMP was also included. It seems that the taste of konoko is mainly ascribable to Glu and AMP, with sweetness derived from Gly and Ala.

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Previously, we have demonstrated that intake of mulberry leaves suppresses increases in the concentrations of serum lipids, hepatic enlargement and atheromatous thickening of the arterial intima in hypercholesterolemic rabbits. In the present study, we evaluated the effect of extracts of mulberry leaves in hypercholesterolemic rabbits in order to clarify the active fractions. The rabbits were fed a 1% cholesterol diet (Ch) concomitantly containing 5% (5Bt·Ch) or 2.5% 1-butanol extract (2.5Bt·Ch), 5% acetone extract (Ac·Ch) and 5% residue (Re·Ch) of mulberry leaves for 14 weeks, respectively. Increases in the concentration of serum total cholesterol and free cholesterol were significantly suppressed in the 5Bt·Ch and Re·Ch diet groups compared with those in the Ch group. Furthermore, a tendency for suppression of lipid deposition in hepatocytes was observed in both the 5Bt·Ch and Re·Ch diet groups. These findings suggest that the hypolipidemic effects of mulberry leaves are exerted by multiple components, and that the 1-butanol extract (recovery 1.03%) contains more active components than the residue (recovery 83.31%).

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We examined the effect of warm water treatment (WWT) on the texture and flavor of cooked rice with the aim of improving the quality of aged or imported rice. By test cooking with small samples, WWT at 50-65°C for 2h increased the stickiness of cooked rice after 1 year of hermetic storage at ambient temperature. The palatability of conventional cooked rice increased to the same level as freshly harvested rice by WWT at 55°C for 24h. WWT at 40°C for 2h or 8h also improved the palatability after 1 year of non-hermetic storage at ambient temperature. One-fifth and 1.6ppm hexanal, the main component of the stale flavor, were detected in cooked rice from 3-year-aged domestic and imported rice, respectively. WWT reduced the hexanal level in both types of rice by half. WWT appears useful for improving the texture and flavor of aged rice.

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Male closed colony (ICR) mice were examined for their taste preference for 0.9% NaCl solution (0.9% preference) and salt taste threshold by the two-bottle test. The 0.9% preference was indicated as the relative intake of 0.9% NaCl solution to total fluid intake (sum of distilled water and 0.9% NaCl solution). The mean value and standard deviation (SD) of 0.9% preference in 332 mice was 45.5% and 19.1, respectively. The preference ranged from 4.2% to 94.5%, and was shown to have a normal distribution by the Kolmogorov-Smirnov test. The salt taste threshold was tested in 61 mice divided into 3 groups according to the strength of 0.9% preference, i.e., 64.6% (mean+SD) and over (Group H), less than 26.4% (mean-SD) (Group L), and others (Group M). In the threshold test, the concentration of NaCl solution in one of the two bottles was raised from 0.0016% to 0.4% stepwise every two days. The threshold in Group H (0.0125%) was lower than that in Group M (0.05%). The threshold in Group L could not be defined, and was considered to exist at a concentration higher than 0.4%. These results indicate that individual difference is related to taste threshold, and could be an effective factor when male closed colony (ICR) mice are used in controlled studies of salt taste.

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A practical method was developed for the large-scale production of a high-glutamine peptide mixture. A gluten ball was freeze-dried, pulverized, and passed through a 48-mesh screen to obtain a starting material. A 10-kg portion of this material as a substrate was mixed with 50L of water containing 100g of actinase AS, and the mixture was incubated at 40°C at pH7.0 for 1h, with the result that about 90% of the substrate was solubilized. The soluble sample was subjected to Sephadex G-15 column chromatography to obtain an oligopeptide fraction with a Glx content of 50.6%. This was then treated with a membrane filter to remove microorganisms, giving a final product for enteral nutrition use.

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For analysis of ascorbic acid (AsA) using high-performance liquid chromatography (HPLC) with an electrochemical detector (ECD), we compared two different methods for preparation of the AsA sample. One used methaphosphoric acid (MPA) as a pretreatment solution for the AsA sample, and the other used EDTA-methanol, as reported previously (J Nutr Sci Vitaminol 40:73 (1994)). AsA in plasma treated with EDTA-methanol was unstable even when stored at 4°C, while that treated with MPA was very stable. After examining several HPLC conditions for the MPA-treated plasma sample, the best was found to be: mobile phase, 0.2M KH₂PO₄-H₃PO₄ (pH3.0) containing 0.5mM dodecyltrimethylammonium chloride and 0.2mM EDTA; flow rate, 1mL/min; column, C18 (4.6×100mm); applied voltage of ECD, +350mV versus Ag/AgCl. Under this condition, dehydroascorbic acid (DAsA), which was reduced with dithiothreitol to AsA before being applied to HPLC, could be analyzed rapidly.

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Retinoid/vitamin A metabolites such as all-trans retinoic acid and 9-cis retinoic acid affect several steps of metabolism in vertebrates. Several studies have shown that retinoids regulate target genes through nuclear retinoid receptors (RARs and RXRs) in order to play their roles. The nuclear receptors are ligand-modulated transcription factors that respond to retinoids, steroids, and thyroid hormones, to control development and body physiology. The 9-cis retinoic acid receptor, RXR, acts as a common heterodimeric partner with several receptors, such as all-trans retinoic acid receptors (RARs), vitamin D₃ receptor, and thyroid hormone receptors. In this study, the author investigated the gene regulation of nuclear retinoid receptors (RARα, -β, -γ and RXRα, -β, -γ) by nutritional status in vivo, and a retinoid-inducible gene in a retinoid target cell in vitro. Retinoid up-regulates the gene expression of only RARβ at the transcriptional level. This suggests specific ligand regulation of RARβ gene expression in the intact animal, and that the altered levels of RARβ according to retinoid status may affect retinoid-inducible gene expression. Moreover, thyroid hormone up-regulates the gene expression of RXRβ but down-regulates the level of RXRγ mRNA in rat tissues. These findings suggest that RXR-mediated signal transduction through molecules such as retinoid, vitamin D and thyroid hormone, may be modulated in part through thyroid hormone. We investigated the molecular mechanisms of retinoid-modulated bone-resorption in vitro, and clearly demonstrated the gene expression of RARα and RXRβ in mature osteoclasts, i.e. bone-resorbing cells. Retinoids up-regulate the bone-resorbing activity and the gene expression of cathepsin K in osteoclasts. These results suggest that osteoclasts are the target cells for retinoids, and that retinoids partly regulate bone metabolism through these cells.

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