It was investigated whether sucrase and isomaltase form an enzyme-enzyme complex in chick intestine or not, and some properties of the disaccharidases were compared with those of other species.
1) Chick intestinal sucrase and isomaltase were shown to exist in the form of an enzyme-enzyme complex from the results of polyacrylamide disc gel electrophoresis, DEAE Sephadex A-25 ion exchange column chromatog-raphy and citraconylation, although the chick intestinal sucrase and isomaltase were not retained on a Sephadex G-200 column.
2) The molecular weights of sucrase-isomaltase complex, maltase I, maltase II, maltase III and isomaltase dissociated from sucrase-isomaltase complex were estimated to be 250, 000, 250, 000, 160, 000, 225, 000 and 80, 000, respectively, by polyacrylamide disc gel electrophoresis.
3) The optimum pH for all the enzymes was 6.0.
4) Km values of sucrase, isomaltase, maltase I and maltase III were 10.0, 3.5, 1.0 and 4.6 mM, respectively. Vmax values for sucrase, isomaltase, maltase I and maltase III were 217.4, 281.4, 147.1 and 454.5 umol substrate hydrolyzed/mg protein/hr, respectively.

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To re-evaluate nutritive values of opaque-2 (02) and brittle-2 opaque-2 (bt₂O₂) maize protein and to re-estimate Gopalan's hypothesis [Lancet, i, 954-957 (1960)] that pathogenesis of pellagra might be related with intake of excess leucine and with chronic consumption of maize or jowar which contains relative high leucine, rats were fed on synthetic diets composed of amino acid mixtures simulating the protein of normal and high-lysine maize, O₂ and bt₂O₂ maize. In order to investigate the effect of intake of excess leucine, leucine was supplemented to 02 and bt₂O₂ diet at the level of 0.43 and 0.73%, respectively, to adjust the ratio of leucine to isoleucine to that of normal maize protein. Judging from body weight gains and carcass nitrogen of weanling rats fed on these diets, the protein quality (amino acid composition) of bt₂O₂ maize was 30% superior nutritionally to that of 02 maize, and body composition of bt₂O₂ diet group were similar to that of casein diet group. Leucine supplementation did not affect these values except for a significant de-crease in plasma valine levels. In young adult rats fed on leucine supplemented 02 diet, excretion of urinary nitrogen increased significantly compared with 02 diet alone, suggesting that a slight amino acid imbalance took place. But leucine supplementation altered neither N¹-methylnicotinamide level in urine nor total niacin levels in the liver and the brain. These results suggest that supplementation of leucine to a high lysine maize diet did not affect tryptophan and niacin metabolism in rats under these conditions.

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The incorporation of dietary ω-3 and ω-6 polyunsaturated fatty acids into the phospholipids of the liver, plasma and heart was studied by feeding rats with diets of increasing amounts of fish oil and/or corn oil up to 5% each for 2 weeks. Irrespective of the sources and amounts of dietary fat, total unsaturated fatty acids were 53-60% of phospholipid fatty acids in liver and plasma, and were 70-73% in heart. In all the animals either given or not given unsaturated fatty acid in diet, the sums of polyunsaturated fatty acids with more than three double bonds such as arachidonic acid, ω-3 polyunsaturated fatty acids and endogenous ω-9 eicosatrienoic acid were always 31-35, 18-20 and 30-38% in liver, plasma and heart, respectively. Dietary ω-3 unsaturated fatty acids and arachidonic acid appeared to be comparably incorporated into the phospholipids and substituted for each other in the phospholipids. These data may suggest that ω-3 polyunsaturated fatty acids compete with arachidonic acid for the C-2 position of the phospholipids.

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The purpose of this paper is to evaluate errors among group regressions predicting oxygen consumption (Vo₂) by heart rate (HR) method, and to obtain the fittest regression for each respective age groups and possibly a single regression for the entire subject population. Twenty male adults participated in the study and were divided into three age groups. Body height, weight, surface area (SA), lean body mass (LBM) and body cell mass (BCM) were determined by the standard anthropometry and the measurement of ⁴⁰K by a whole body (human) counter. At the submaximal work test, Vo₂ and HR were calculated at 4 to 6 grades of work loads on a bicycle ergometer. All correlation coefficients of Vo₂ to HR for groups were over 0.885 (p<0.001), while regression showed differences in slopes and intercepts between age groups. After correction applying indices of body com-position and the ratio to resting HR (HRR), correlation coefficients of the old age group became greater, whereas correlation coefficients for the other two groups were almost unchanged when Vo₂ were corrected by SA, LBM or BCM and related to HR. The age-difference in the group regressions disappeared in the relation between Vo₂ corrected by LBM and HR. Among ten sets of relation of corrected Vo₂ and HR (or HRR), only three indicated the age-difference clearly. These facts suggest the possibility of a single regression for all groups. Tentative regression equation for all the study-subjects showed the highest value of correlation coefficient, 0.936 (p<0.001) in case that Vo₂ corrected by LBM or BCM was related to HRR. It was concluded that the group regression should be constructed by adopting HR (for young age groups) or HRR (for old age groups) with the correction of Vo₂ by SA, LBM or BCM (for both young and old age groups). We can use additionally body weight (for only old age groups); and that a single group regression, covering an age-range up to 50 years old, is possibly applied in the relation between corrected Vo₂ by LBM or BCM and HRR, with an error of about 25%

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Secretory IgA (sIgA) and monomeric IgA (mIgA) were purified from normal rat bile, and their role in the gastrointestinal tract was investigated. Biliary sIgA has a molecular weight of approximately 400, 000 daltons and a sedimentation constant of 11.75. Thus, sIgA obtained from rat bile had physicochemical properties similar to those reported for sIgA in other secretions, and probably consists of L-chains, a-chains and secretory component. After in vitro incubation with trypsin or intestinal fluid, sIgA remained intact, whereas mIgA was hydrolyzed. Rats challenged repeatedly with dinitrophenylated bovine serum albumin (DNP-BSA) had specific IgA antibody against DNP in the bile and feces as measured by a radioim-munoassay using [³H]-DNP-lysine. Our results demonstrate a possibility that biliary sIgA, not mIgA, has an important role which inhibits the absorption of foreign antigen from intestine.

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