Small-intestinal disaccharidases, including sucrase-isomaltase (S-I) and lactase-phlorizin hydrolase (LPH), are regulated by dietary nutrients at multiple steps of synthesis, post-translational modifications and degradation of S-I and LPH. These include 1) elevation of S-I mRNA and LPH mRNA levels induced by dietary carbohydrates, and 2) alteration of post-translational modification and/or enhancement of degradation of S-I and LPH caused by intake of diets rich in long-chain triglycerides or protein, due presumably to an increase in the luminal factors involved in degradation of disaccharidases on the microvillar membranes, e. g., bile acids and pancreatic proteinases. Thus, variation in the digestive-absorptive capability of carbohydrates in intestinal absorptive cells is determined not only by the adaptive response to dietary carbohydrates, but also modified by intake of other macronutrients, i. e., fat and protein.

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The concentrations of lycopene and β-carotene in human serum were measured before and after continual ingestion of tomato juice. The change in the level of cholesterol during this period was investigated simultaneously. Sixty-five female students were divided into 4 groups. They ingested either 1, 2 or 3 cans of tomato juice per day and the control group received a can of apple juice per day for 4 weeks. The lycopene level in serum showed a significant increase following the ingestion of tomato juice. In the case of subjects ingesting 2 or 3 cans daily, the level in serum increased to over three times the level of serum lycopene determined at the start of the experiment. Although the β-carotene content of the tomato juice was about one-thirtieth that of lycopene, the β-carotene level in serum was about double in the sublects who ingested 3 cans daily. These results suggest that continual ingestion of tomato juice is effective for raising the serum levels of lycopene and β-carotene. Although most of the lycop ne in the tamato juice was the all-trans type, a large amount of the cis-isomer was detected in the serum of the subjects after tomato juice ingestion. This would be due mainly to the isomerization reaction in the body. No significant changes in the levels of serum lipids, such as LDL-cholesterol, were observed. This suggests that the increase in the level of carotenoid in serum by ingesting tomato juice dose not induce an increase in the level of serum lipid.

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A tristearin-rich triglyceride was prepared by full hydrogenation of soybean oil. The digestibility of the fully-hydrogenated soybean oil (FH oil) and its influence on lipid metabolism were compared with those of ordinary soybean oil. Growth retardation, poorer food efficiency ratio, and a lower adipose tissue weight were observed in rats fed an AIN-76-based standard diet and a hypercholesterolemic diet containing 19% FH oil compared with those fed a diet containing 20% soybean oil. The tristearin in the FH oil was the most resistant to gastrointestinal digestion (0.1-0.2%). As a result of this poorer digestibility, the absorption of coexisting lipids, liver lipid concentration, and serum triglyceride level in the FH oil group were significantly lower than those in the soybean oil group. The influence of the fat source on the level of serum cholesterol differed between the standard diet and the hypercholesterolemic diet. These results indicate that FH oil is resistant to gastrointestinal digestion and is rarely utilized as an energy source.

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Four-week-old male Wistar rats were fed a vitamin E (VE) -deficient diet for 8 weeks, followed by intraperitoneal injection of DL-buthionine- [S, R] -sulfoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase, at 1mmol/kg body weight. Rats in glycine (Gly) and/or γ-glutamylcysteine ethyl ester (γ-GC) -treated groups were injected intraperitoneally with Gly and/or γ-GC three times at 0.7mmol/kg body weight in addition to BSO administration. GSH depletion by BSO administration was accompanied by a decrease in the level of renal TBA (2-thiobarbituric acid) and a marked increase in the renal lipofuscin content. γ-GC treatment increased the renal GSH content and inhibited the increase in the renal lipofuscin content. The increase in serum creatinine and the decrease in renal enzyme activities in rats administered BSO were inhibited by γ-GC treatment. γ-GC treatment did not provide complete protection from epithelial necrosis in the proximal renal tubules, but such degeneration in rats treated with γ-GC was observed only in a narrow area of the S3 segment near the descending thin limb of Henle's loop. These results suggest that GSH plays an important role in preventing lipofuscin production through reaction of lipid peroxides with amino acids.

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An experiment was carried out to determine the effect of dietary protein levels on urinary calciun excretion, and the calcium contents of the kidney, serum and femur in female rats. Casein was the protein source, and the protein content in the diet was 10% (C-10), 20% (C-20) or 40% (C-40). Fischer-strain rats 4 weeks of age were fed one of the experimental diets for 5 weeks.
The serum parathyroid hormone (PTH) level was also measured. The degree of enlargement and pathological features of the kidney were observed. The results obtained were as follows: 1) The C-40 group exhibited a higher level of urinary Ca excretion. 2) Enlargement of the kidney was recognized in the C-10 and C-40 groups. 3) The kidney Ca content in the C-10 group was significantly higher than in the other groups. 4) The serum ultrafiltrable Ca content in the C-40 group was lower than in the other groups. 5) The serum PTH content in the C-40 group was higher than in the other groups. These results indicate that the dietary protein level may influence Ca metabolism in the kidney.

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The morphology of the myenteric plexus of the gastrointestinal tract during postnatal development was examined in the stomach and small intestine of newborn (about 6h after birth), 2-, 6- and 12-week-old rats using the Champy-Maillet (ZIO) method. The myenteric plexus was distributed continuously from the stomach to the ileum, even in pups immediately after birth. In particular, the network pattern of the myenteric plexus in the pylorus was denser than that in the small intestine. In the newborn rat, however, the outline of the nuclei of the enteroglial cells and ganglionic cells in the ganglion was not clear. The interstitial spaces of the network in the myenteric plexus enlarged with postnatal development of the gut, and then a compact autonomic ground plexus was constructed after repeated elongation and branching of the enteroneuronal processes.

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The dietary habits, life style and subjective symptoms of 30 physical conditions were investigated in 747 junior high school students using a specially designed questionnaire. Blood samples were also tested for biochemical parameters, and blood pressure was measured. Milk, eggs and vegetables were eaten daily by more than 50% of the students, whereas fish, soybean products, algae and potatoes were eaten daily by less than 20%. Some students were found to have several undesirable eating habits, such as irregular timing of meals, having no breakfast, or eating alone. On average, a student complained of 8.5 subjective symptoms out of the 30 items examined. Students who had undesirable eating habits or a poor life style complained of many subjective symptoms. It is suggested that better dietary habits and life style are necessary for maintaining the good physical condition of junior high school students.

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An artempt was made to increase the Lascorbic acid content in the tops of head lettuce (crisp head and butter head types) by changing the general culture solution to a highly concentrated solution of L-ascorbic acid immediately before harvest. During the soaking treatment with a 1, 000ppm solution of L-ascorbic acid or its sodium salt, the L-ascorbic acid content in the head lettuce tops was at least 4 times higher than that of the control. It was found that much of the absorbed L-ascorbic acid moved to the top and accumulated there. These results suggest that this culture technique may be able to produce leaf vegetables containing abundant L-ascorbic acid.

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An attempt was made to increase the iron content in the top of head lettuce (butter head type) by changing the general culture solution to a highly concentrated solution of iron (III) ammonium citrate immediately before harvest. During the soaking treatment, the iron content in the lettuce top increased as the iron concentration of the treatment solution rose to 100ppm, reaching about 4 times the content of the control. The contents of minerals other than iron in the tops did not become much lower when iron (III) ammonium citrate was introduced for 24h. These results suggest that the present culture technique might be able to produce leaf vegetables containing a high concentration of iron.

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