The effect of spontaneous running exercise on muscle enlargement and sex differences in muscle hypertrophy were studied using morphological and biochemical approaches. Male and female weaning rats were placed in steel cages with free access to a running wheel for spontaneous exercise training. The running activity of female exercising rats reached more than twice the activity level of male exercising rats over 7 weeks of training. Muscle weights i. e., heart, gastrocnemius, and quadriceps, were increased in the male and female exercising groups; the quadriceps muscle weight increased with increasing running activity, and there was a significantly positive correlation between them. Morphological changes in muscle fibers were examined at the midpoint of the rectus femoris muscle. Male rats had much larger and longer muscle fibers than female rats, while there was no difference in fiber number between the sexes. Running exercise increased muscle fiber number and extended the fiber length significantly in both sexes, although the cross-sectional fiber area was not changed. Thus morphological studies at the midpoint of the muscle belly suggested that the spontaneous exercise-induced increase in muscle mass might be attributable to an increase in fiber number and extension of fiber length. Muscle RNA and DNA contents were increased in the male and female exercising groups. The amount of 3-methylhistidine excretion in urine was decreased in the female exercising group, but there was no change in the male groups. The RNA data supported the notion that spontaneous running exercise enhanced muscle protein synthesis in both sexes. It is concluded that the sex difference in the morphology of muscle fibers is present from the beginning, but that there is no sex difference in the direction of morphological or biochemical changes following spontaneous running exercise.

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The influences of dietary lipids on zinc metabolism in rats fed diets containing either low (<1ppm), sub-optimal (10ppm) or adequate (25ppm) levels of zinc were examined. Serum alkaline phosphatase (APase) activity and zinc levels in the serum, distal small intestine (ileum) and femur were decreased in rats fed either a 5% corn oil-zinc deficient or a 5% beef tailow-zinc deficient diet containing 20% demineralized soybean protein compared with those of rats fed the respective zinc-adequate diets. However, there was no difference in these parameters between the two lipid groups. When rats were fed 20% protein diets containing 10ppm zinc, a 20% beef tallow diet caused increases in the serum and femur zinc levels campared with those of rats fed the 5% beef tallow diet, while no difference was observed between the groups fed 5% and 20% corn oil diets. Serum APase activity was increased by feeding the rats 20% corn oil and 20% beef tallow diets. Rats fed low-protein diets (10%) had higher serum and femur zinc levels and serum APase activity than rats fed 20% protein diets, and the difference in the femur zinc levels was increased between the groups fed the 20% omrn oil and 20% beef tallow diets. These results suggest that feeding rats on high-lipid diets affects their zinc metabolism, and that high bone zinc levels in rats fed a high-beef tallow diet are probably due to a lowered zinc requirement in the animals.

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The effects of Tienchi ginseng [Panax notoginseng (Burk.) F.H. Chen] on blood pressure and lipid metabolism were investigated using stroke-prone spontaneously hypertensive rats (SHRSP) as an animal model. An experimental diet was prepared by adding 3% (w/w) Tienchi ginseng powder to the control diet (CE-2, Clea Japan Inc.), and thiS was made freely available to the rats with drinking water for 7 weeks. The elevation of systolic blood pressure was effectively suppressed after 5 weeks on the diet, and thereafter the blood pressure remained almost constant (approximately 230 mmHg). A significant difference relative to the control group was observed at 6 weeks on the diet. Although there was no significant difference in serum lipid concentration, the serum apoE concentration was increased significantly. This increase in apoE was due mainly to elevation of high-density lipoprotein (HDL) 1, which is one of the HDL subfractions and rich in apoE. HDL1 is known to play an important role in reverse cholesterol transport from peripheral tissues to the liver. In addition, the apoB/apoA-I ratio, which is considered to be an atherogenic index, was significantly reduced. On the other hand, in the liver, no significant change was observed in lipid content or the activities of hepatic microsomal enzymes (cholesterol 7α-hydroxylase, acyl-CoA: cholesterol acyltransferase) related to cholesterol metabolism. These results suggest that Tienchi ginseng powder may exert effective anti-hypertensive and anti-atherogenic actions.

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L-arabinose, a natural, sweet and less absorptive pentose, has been recognized to have a selective inhibitory effect on intestinal sucrase activity. In this study, we evaluated the effects of L-arabinose on gastrointestinal digestion and absorption of ¹⁴C-labeled sucrose in rats, and also studied the suppressive effects of L-arabinose on the increase in blood glucose after sucrose loading. Uniformly ¹⁴C-labeled sucrose was orally administered at a dose of 2.5g/kg with or without L-arabinose, and cumulative expiratory 14CO₂ and residual radioactivities in the gastrointestinal tract were measured for 6h. The cumulative expiratory ¹⁴CO₂ was significantly reduced dose-dependently by L-arabinose (50, 250mg/kg), and also a large quantity of undigested ¹⁴C-labeled sucrose and its metabolites was observed in the cecum in L-arabinose-treated rats. We also observed potent suppressive effects of L-arabinose on the increase of blood glucose after sucrose loading in rats. These results indicate that L-arabinose delays and reduces the digestion, absorption and net energy of sucrose when both are simultaneously ingested.

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Changes in the lipid components of tofu during nyufu production were followed. The main components were found to be neutral lipids (90.4-92.9%) with 4.1-5.3% glycolipids and 3.0-4.3% phospholipids. Triglycerides were reduced to approximately half in fungi-inoculated tofu and to approximately one fourth in nyufu after one month of aging. Abundant ethyl esters of fatty acids were observed in nyufu. Phosphatidylcholine (PL) was abundant in the phospholipids of nyufu. PL promoted emulsification and dispersal of neutral lipids-protein which presumably contributed to the cheese-like physical properties and texture unique to nyufu. On the other hand, nyufu was rich in unsaponifiable matter such asγ-and δ-tocopherols and β-sitosterol, indicating that nyufu is a nutritionally excellent food with antioxidant and blood cholesterollowering activities.

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Three types of commercially available heat-treated milk (low temperature long time-treated milk (LTLT milk), high temperature short time-treated milk (HTST milk) and ultra-high temperature-treated milk (UHT milk)) were evaluated for their peptic digestibility using 16% SDS-polyacrylamide gel electrophoresis and Western blot analysis wish anti-bovine casein, anti-bovine β-lactoglobulin (β-LG) and antibovine α-lactalbumin (α-LA) antibodies. The digestion profile of casein was similar for all the types of milk, and the intact proteins of casein disappeared rapidly upon peptic digestion. α-LA in the LTLT and HTST milks was more resistant than casein to peptic digestion, and this resistance was also maintained in UHT milk, although to a lesser extent. Similarly, β-LG in the LTLT and HTST milks was resistant to peptic digestion, but this resistance was almost lost in UHT milk, so that β-LG in UHT milk was easily digested by pepsin, in a similar manner to casein. In rats, β-LG in UHT milk was digested more rapidly in the stomach than that in HTST milk. These results indicate that α-LA and β-LG differ in their peptic digestibility among different heat-treated milks, and that loss of resistance to peptic digestion of β-LG in UHT milk may have important consequences for reducing its allergenic properties.

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The protein cantent of black matpe cotyledon decreases gradually following germination, whereas that of the hypocatyl increases slightly in the first week after germination. Cotyledon and hypocotyl proteins in ungerminated seeds were separated into three peaks (P1, P2, P3 in elution order) by column chromatography on Sephadex G-200. The proportions of P1, P2 and P3 were 7: 2: 1 in cotyledon, and 4: 5: 1 in hypocotyl. After germination in the catyledon, the lower-molecular-weight peak area became broader while the high-molecular-weight peak area (storage protein) remained. In the hypocotyl and radicle, the lowermolecular-weight peak area occupied a greater proportion, and in the plumule the high-molecular-weight area developed. Protease inhibitor activity was detected only in the cotyledon of ungerminated and germinated seeds and the hypacatyl of ungerminated seeds. ln the catyledan it decreased during 7 days of germination. In the cotyledon, APase, BAPAase, CPase and LNAase activities reached a maximum in one or two days from the beginning of germination. In the hypocatyl, APase, CPase and LNAase activities increased in 5 or 7 days from the beginning of germination. The dominant free amino acids of 7-day hypocotyl and radicle were Laspartic acid, L-valine, L-isoleucine and L-arginine.

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Porcine small intestine (PSI) develops a specific offensive odor after storage for only 0.5 to 1 day at 20°C, and bacterial counts increase exponentially during this storage period. Pretreatment at 500 MPa for 10 min at 20°C was found to drastically reduce microbial counts and maintain PSI freshly for at least 1 day after the treatment in terms of microbial counts, amounts of volatiles, and organoleptic features. Anaerobic storage of PSI was unable to inhibit offensive odor development, but gave a gas chromatographic pattern similar to that observed when PSI was stored under control storage conditions. Some chemicals, including those listed as legal food additives, retarded the evolution of the offensive odor and bacterial growth. However, these chemicals, added at levels below the legally permitted limits, were unable to effectively suppress development of the offensive odor. In storage experiments, the amount of methyl mercaptan (MM), the main volatile responsible for the offensive odor, was found to correlate significantly with the count of anaerobic bacteria. Furthermore, inoculation of anaerobes, among the various microbial groups separated from PSI, onto fresh PSI that had been pasteurized by high-pressure pretreatment led to development of the same, typical offensive odor (MM) as that produced by control PSI after storage. These results indicate that evolution of the offensive odor of PSI during storage is mostiy, if not completely, attributable to the growth of anaerobes.

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Methyl mercaptan (MM) -producing anaerobes in porcine small intestine (PSI) during storage were isolated and identified by enriched culture using methionine. Some facultative anaerobes were found to produce MM, among which Proteus mirabilis predominated both in the number isolated and the amount of MM produced. Sulfur-containing amino acids, such as methionine and cystine, enhanced the production of MM by the bacterium both in situ and in vitro. These results indicate that the evolution of MM during storage of PSI is due mainly to Proteus mirabilis.

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The effect of a dried yeast diet on bacterial metabolism in the intestine was studied in rats. Male Sprague-Dawley rats were fed either a purified control or a 20% dried yeast diet for 3 weeks. The concentrations of organic acids (formic acid, acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, iso-valeric acid, malic acid, succinic acid and lactic acid) in feces were significantly increased in rats fed the 20% dried yeast diet in comparison with those fed the control diet. The increases in the concentrations of acetic acid and lactic acid were particularly noticeable. The cecum weight in rats fed the 20% dried yeast diet was approximately twice that in rat fed the control diet. The pH of the cecal contents was significantly decreased according to the concentration of organic acids produced by cecal bacteria in rats fed the 20% dried yeast diet. These results indicate that dried yeast is effective for improving intestinal conditions.

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The trans-fatty acid content of daily meals in a university refectory and a dormitory cafeteria was measured for 7 days. The trans acid content, mainly t-18: 1, of the meals per day was on average 0.63g/day, ranging from 0 to 1.29g/day. The observed values were lower than those estimated in the recent national nutrition survey, the annual statistics of edible fats and oil, and the fatty acid composition data for refined edible processed fats, i. e. approximately 1.8g/day.

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[in Japanese]

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