1. The aim of the present study was to determine whether oral ingestion of raw soya-bean flour, which contains trypsin inhibitors, alters the release of cholecystokinin (CCK) in man.

2. Eleven healthy volunteers ate two mixed meals: one with raw soya-bean flour and the other with soya-bean flour that had been heat-treated. The two flours inhibited 34 and 3 mg trypsin/g flour respectively.

3. CCK was measured in plasma using a bioassay based on the release of amylase (EC 3.2.1.1) from dispersed rat pancreatic acini.

4. The peak CCK response was 168 (SE 8.1) pmol/l with raw soya-bean flour but 4.9 (SE 2.8) pmol/l with heat-treated flour (P < 0.05).

5. We conclude that ingestion of raw soya-bean flour increases CCK release in man and that heat treatment which reduces the trypsin inhibitor content of the flour also diminishes its CCK-releasing effect.

1. Studies were made on liver stores of retinol in aborted human fetuses and stillborn babies in relation to gestational age, fetal size and maternal retinol status. The mothers belonged to low-and high-income groups (LIG and HIG respectively) in urban Baroda.

2. Fetal weights were less than those reported by Widdowson (1968) for similar gestational ages and the deficits were greater in LIG.

3. The combined mean values (μg/l) for maternal serum retinol for all gestational ages were 193 for LIG and 261 for HIG. They were found to decline in late pregnancy in the former but not significantly in the latter.

4. Fetal liver retinol concentrations were much lower than those reported for healthy Thai subjects by Montreewasuwat & Olson (1979) in early pregnancy but showed complete ‘catch up’ in late pregnancy for HIG and to a considerable extent for LIG.

5. Significant correlations were found between maternal serum retinol, fetal liver retinol and fetal growth.

6. These findings stress the importance of adequate vitamin A supplies during pregnancy to prevent vitamin A deficiency and intra-uterine growth retardation in the newborn.

1. Studies were made on the vitamin E status of the newborn as judged by cord serum vitamin E and erythrocyte haemolysis in vitro in relation to gestational age, birth weight and maternal vitamin E status in subjects belonging to low (LIG)- and high (HIG)-income groups in urban Baroda.

2. In the case of full-term infants, the mean values for maternal serum vitamin E (mg/l) for LIG (n 73) and HIG (n 43) were 9.9 (SE 0.4) and 11.6 (SE 0.5). The corresponding values for cord serum vitamin E were 3.6 (SE 0.2) and 4.6 (SE 0.2) mg/l.

3. Serum vitamin E levels (mg/l) were lower in premature infants (2.3 (SE 0.2); n 20) and low-birth-weight full- term infants (2.9 (SE 0.2); n 25) than in full-term normal infants (4.2 (SE 0.1); n 91). This was associated with differences in maternal serum vitamin E levels (7.4 (SE 05), 8.2 (SE 0.5) and 11.1 (SE 0.3) respectively). The differences were more marked for LIG.

4. A negative correlation was found between serum vitamin E and erythrocyte haemolysis in vitro in the case of maternal blood but not in cord blood.

5. These results suggest that maternal vitamin E deficiency is one of the features associated with prematurity and intra-uterine growth retardation.

1. The hydrolysis of sugar alcohols of the disaccharide type such as lactitol, maltitol and Palatinit® (the latter an equimolar mixture of 6-O-α-D-glucopyranoside-D-mannitol and 6-O-α-D-glucopyranoside-D-sorbitol) by homogenates of human intestinal biopsies were compared with corresponding natural disaccharides such as lactose, maltose and isomaltose. Seven of the human biopsies were normal with regard to their disaccharidase activities, while twelve biopsies showed decreased levels of disaccharidase activities.

2. All biopsies, normal as well as abnormal, showed essentially the same capacity to hydrolyse the sugar alcohols. Activities towards lactitol (0.34 IE/g protein (where IE = μmol disaccharide hydrolysed/min at 37°)) and Palatinit (2.50 IE/g protein) were only 1.3% of those towards lactose and isomaltose. The activity towards maltitol was much higher (19.1 IE/g protein), approximately 10% of that towards maltose and about as high as the activity towards trehalose. This finding indicates that despite the fact that lactitol and Palatinit were poor substrates, significant amounts of ingested maltitol might be digested and utilized by man.

3. Glucose release was reduced by approximately 25% when maltitol or Palatinit were present at concentrations equal to those of maltose. Palatinit decreased the hydrolysis of sucrose by 12%. Lactitol had no inhibitory effect on the hydrolysis of disaccharides.

1. The evidence is accumulating to suggest that glycine, the simplest amino acid, is conditionally essential in man. Benzoic acid, by conjugation with glycine to form hippuric acid, is known to deplete the free glycine pool of the body. Glycine is one substrate for the enzyme glutathione synthase (EC 6.3.2.3) and in the inborn error of metabolism in which glutathione synthase function is defective, increased quantities of 5-oxoproline are excreted in the urine.

2. An oral dose of 4–10 g sodium benzoate was given to six normal adults to deplete the metabolic pool of glycine, and the urinary excretion of 5-oxoproline was followed for 6 h. In five of the six, a significant increase in the urinary 5-oxoproline was seen within 3 h.

3. These-findings show that 5-oxoprolinuria can result from limited glycine availability, and may provide a useful test for assessing glycine sufficiency in a range of physiological and pathological states.

1. Various biochemical variables of the skins of rat dams and their fetuses in which protein-energy malnutrition was induced during pregnancy were analysed.

2. One group of dams was fed on a 200 g protein/kg diet as a control and the other was fed on a 60 g protein/kg diet as an experimental group. Each group of dams was fed from day 13 of gestation until day 22.

3. Water, protein and hexosamine concentrations of the fetal skins in the malnourished group were greater than those in the control group, whereas in the dams′ skins, protein concentration was greater in the malnourished group than in the control group.

4. Extractability of collagen with neutral salt and pepsin showed no difference between the groups in the skins of fetuses and dams. The content of type III collagen in the fetal skin did not differ between the groups, but was increased in the malnourished dams′ skins compared with that of the control group.

5. The present study showed that protein-energy malnutrition during pregnancy significantly affects the metabolism of the skin in both fetuses and their dams. Furthermore, the skins of fetuses and dams are structurally altered in different ways by this nutritional stress.

1. Groups of four conventional (CV) rats ate natural or purified diets either with or without 100 g fat/kg and drank 0.235 M-sodium nitrate. The fats tested were butterfat, coconut oil, olive oil, maize oil and safflower oil.

2. Decreased urinary excretion of N-nitrosoproline (NPRO) was observed in rats fed on fat-supplemented diets compared with those fed on low-fat diets, with butterfat having the greatest effect of the fats tested.

3. Reduced excretion of NPRO was not the result of inhibition of the intragastric N-nitrosation reaction or absorption of nitrosamine from the gastrointestinal tract.

4. The availability of nitrite in aqueous solution was decreased by the fat diets but the effect was similar in all the fats tested.

5. Nitrate reductase activity was present in the forestomach contents of CV rats at pH > 4 and was apparently inhibited by feeding a fat diet. No nitrate reductase activity was detected in stomach contents of germ-free rats.

6. Nitrate reductase activity in stomach and small intestinal tissue was not altered by feeding a fat diet.

7. It was concluded that nitrate reductase activity in stomach contents was of microbial origin and the decreased urinary excretion of NPRO on feeding the fat diets was mainly due to the inhibition of nitrate reductase activity in stomach contents.

1. Homogenized and diluted faeces (66.6 g/l) collected from one human source on three different months was incubated with four standard substrates (oat bran, wheat bran, red kidney beans (Phuseolus vulgaris) and guar gum) for 4, 8, 12 and 24 h.

2. Neutral-detergent fibre and organic matter (OM) digestibility measurements and gas production (ml gas/g OM) were influenced by substrate and incubation period but not by day of collection.

3. Production of short-chain fatty acids (SCFA) (mmol/g OM) was a function of substrate and incubation period but not day of collection at 4, 8 and 12 h. Rapidly fermentable substrates such as red kidney beans and guar gum did not ferment beyond 12 h and SCFA values were not different at 24 h.

4. Substrates differed in amount, rate and type of SCFA produced.

5. The results indicate that human faeces collected on different occasions were sufficiently uniform to yield similar in vitro fermentation findings among collections. Therefore, it is concluded that human faecal material is a practical source of micro-organisms to evaluate the fermentation properties of substrates.

1. Four groups of rat pups were reared: mother-reared (MR) control (well-fed) and undernourished (MRC and MRU respectively) and artificially reared (AR) control and undernourished (ARC and ARU respectively). Pups for artificial rearing were fitted with a gastric cannula on postnatal day 5 and were fed, by intermittent gastric infusion, expressed rats′ milk (days 5–7), mixtures of rats′ milk and milk-substitute (days 8–16), and milk-substitute only (days 17–20). Solid food was available to MR pups throughout and to AR pups from day 14. Undernutrition, imposed from postnatal days 5 to 25, was effected initially by underfeeding the mother (MRU) or by infusing restricted quantities of milk (ARU). Weaning was at 21 d and undernutrition from day 21 to day 25 was by restricting the supply of solid food. All rats were fed ad lib. from 25 d.

2. The developmental milestone, eye-opening, was delayed by undernutrition but unaffected by artificial rearing.

3. Growth curves in body-weight during the refeeding phase were influenced most by previous undernutrition and to a lesser extent (also negatively) by artificial rearing.

4. Fourteen measures of body and organ growth were taken at autopsy at 39 weeks. Twelve measures were affected by nutrition and only four by rearing (weight of whole body, epididymal fat pads, renal fat pads and adrenals).

5. AR rats had lighter epididymal and renal fat pads than MR rats perhaps due to the low fat content of the expressed milk they received early in artificial rearing.

1. Two groups of vervet monkeys (Cercopithecus uethiops) were fed on high-cholesterol diets which differed only with respect to the protein source. In one group casein was the only protein source, while the other group received only soya-bean protein.

2. Samples of blood, bile and liver biopsy material were collected at the commencement of the study and at 3-monthly intervals until termination 12 months later.

3. At the end of the experimental period all the animals (n 19) had high plasma cholesterol levels and had developed pigment gallstones, the compositions and weights of which were not related to the protein source or to plasma cholesterol levels. Gallstone weight was related to the presence of acidic and sulphated mucins in gallbladder mucosa. We were also unable to confirm the hypocholesterolaemic effect of soya-bean protein which has been demonstrated previously in rhesus monkeys and hamsters. Bile composition, and plasma lipids did not differ significantly between the casein-fed and soya-bean fed animals. Lithogenic index was below 1 for both groups and did not differ significantly between the two groups.

4. No significant difference was found in the severity ofcholelithiasis between the casein-fed and the soya-bean-fed animals.

1. Merino sheep fed on a diet of chopped wheaten hay, chopped lucerne (Medicago saliva) hay and oat grain were the source of rumen contents for the study. The diet contained (mg/kg dry weight) 3.3 copper, 0.24 molybdenum and 2.8 sulphur. The effects of adding between 5 and 25 mg Mo/kg as ammonium molybdate (AM) or tetrathiomolybdate (TTM) on the distribution and forms of Cu and Mo in rumen contents were investigated in vivo and in vitro.

2. Approximately 88 % of the Cu and 94% of the Mo in rumen contents were associated with the solid phase. When AM or TTM was added to rumen contents in vivo or in vitro the proportion of these elements in the solid phase was increased at the expense of the fluid phase.

3. The addition of AM and TTM to rumen contents also decreased the proportion of Cu that was soluble in trichloroacetic acid (50 g/l; TCA) and increased the proportion of Cu that was not extractable by sequential treatment with TCA and neutral detergent.

4. Column chromatography of neutral-detergent extracts of rumen contents revealed that TTM treatment caused Cu to be strongly bound to proteins of high molecular weight.

5. Addition of sulphide to rumen contents did not result in significant changes in the distribution of Cu between the fluid and solid phases, or in the solubility of Cu in TCA.

6. It is postulated that constant removal of TTM from the fluid phase via reaction with proteins and other macromolecules in the solid phase results in greater formation of TTM in vivo than would be expected from solution chemistry. The molybdo-proteins so formed are strong chelators of Cu and may be the agents responsible for the decrease in Cu absorption in animals that consume diets containing high concentrations of Mo.

1. Eight pigs with a mean weight of 48 kg were given, at a constant daily rate, diets of low (0.15) or high (0.30) protein content, very deficient in lysine, with or without a supplement of L-lysine (3.7 g/kg).

2. Measurements of nitrogen and energy metabolism were made in four successive 14 d periods in a Latin-square design.

3. The rate of protein accretion was substantially increased by increases in both protein and lysine supply, but the rate of heat production was not significantly changed.

4. The rate of fat deposition varied inversely with the rate of protein accretion, being reduced by both protein and lysine supplements.

5. The relation between heat production and protein accretion (allowing for a constant energy cost of fat deposition) suggested that heat production increased with additional protein accretion less when protein quality was improved than when more protein was given.

1. The interrelations between protein accretion and whole-body protein turnover were studied by varying the quantity and quality of protein given to growing pigs.

2. Diets with 150 or 290g lysine-deficient protein/kg were given in hourly meals, with or without lysine supplementation, to female pigs (mean weight 47 kg).

3. After the animals were adapted to the diets, a constant infusion of [14C]urea was given intra-arterially for 30 h, during the last 6 h of which an infusion of [4,5-3H] leucine was also infused at a constant rate. At the same time, yeast-protein labelled with 15N was given in the diet for 50 h.

4. The rate of urea synthesis was estimated from the specific radioactivity (SR) of plasma urea. The rate of leucine flux was estimated from the SR of plasma leucine. The irrevocable breakdown of leucine was estimated from the 3H-labelling of body water. Total N flux was estimated from the 16N-labelling of urinary urea.

5. Addition of lysine to the low-protein diet significantly increased N retention, with a substantial reduction in leucine breakdown, but there was no significant change in the flux of leucine or of total N.

6. Increasing the quantity of the unsupplemented protein also increased N retention significantly, with concomitant increases in leucine breakdown and in the fluxes of leucine and of total N.

7. It is concluded that a doubling of protein accretion brought about by the improvement of dietary protein quality is not necessarily associated with an increased rate of whole-body protein turnover.

1. Studies have been made of the time-sequence of protein metabolic and hormonal changes following an abrupt increase in carbohydrate or fat intake. [3H]leucine and [14C]urea were infused for 72 h, via the aorta, into fourteen female pigs (30–38 kg body-weight). At 24 h after the start of the infusion their feed was either changed to one of two isonitrogenous diets containing additional starch (group BS, five animals) or fat (group BF, five animals), or remained unaltered (group BB, four animals). The distribution space of urea was measured by the dilution of a single dose of [14C]urea given both 48 h before and 48 h after the change in diet. The changes in the concentration and specific radioactivity of blood leucine were used to infer changes in protein turnover and those of plasma urea to measure total amino acid catabolism. The concentrations of blood glucose and plasma insulin and cortisol were also measured at approximately two-hourly intervals for the 48 h period following the change in diet.

2. Within 4 h of either change in diet blood leucine concentration was lowered and the leucine specific radioactivity was raised above that in group BB, but after 24 h both the concentration and specific radioactivity of leucine returned to values similar to those in group BB. Eventually the blood leucine specific radioactivity was slightly but not significantly reduced below that of group BB.

3. The addition of starch to the diet significantly reduced the synthesis and concentration of urea within 4 h but, although the addition of fat to the diet eventually lowered the urea concentration and synthesis, both changes were delayed for 18–24 h.

4. In group BS plasma glucose and insulin rose after the addition of starch, but after 24–36 h both returned to values that were the same as those in the animals that received the same diet throughout (group BB). The addition of fat to the diet altered neither blood glucose nor plasma insulin concentrations. The addition of either carbohydrate or fat to the diet eventually reduced pIasma cortisol concentrations, but the change did not occur until 24 h after the change in diet.

5. The results suggest that alterations in non-protein energy supply exert their immediate effect on the degradation of whole-body protein. They do not exclude the possibility that these early changes may reflect opposing changes at different sites. The results also suggest that the rate of urea synthesis may be controlled by the balance between the concentrations of insulin and cortisol, but that under the conditions of these experiments there was little relation between these hormones and the turnover of body protein as measured by the turnover of blood leucine.

1. The cellular proteins of Butyrivibrio jibrisolvens, Lactobacillus casei, Megasphaera elsdenii, Selenomonas ruminantium and Streptococcus bovis were labelled by growth in the presence of L-[14C]leucine, and the breakdown of labelled protein was measured in incubations of these bacteria with rumen fluid to which unlabelled 5 mM-L-leucine was added. The rate of protein breakdown was estimated from the rate of release of radioactivity into acid-soluble material.

2. Protein breakdown occurred at different rates in different species. The mean rates for B. fibrisolvens, L. casei, M. elsdenii, Sel. ruminantium and Str. bovis were 28.6, 18.1, 17.7, 10.5 and 5.3% /h respectively in samples of strained rumen fluid (SRF) with different protozoal populations. Rates of 3% /h or less were found in SRF from ciliate-free sheep or in faunated SRF from which protozoa had been removed by centrifugation. Further removal of mixed rumen bacteria had little effect. Suspensions of washed protozoa degraded bacterial protein at rates which were of the same order as those found in SRF.

3. The rate of breakdown of bacterial protein in different samples of SRF tended to increase as the numbers of small entodiniomorphid protozoa increased. The numbers of larger entodiniomorphs and holotrichs had no obvious influence on this rate.

4. Autoclaved and u.v.-treated bacteria were generally no different from live bacteria in their susceptibility to breakdown in SRF from faunated sheep, indicating that endogenous protein turnover was not a significant cause of bacterial protein catabolism.

5. The rate of bacterial protein breakdown was unrelated to the proteolytic activity of SRF.

6. It was concluded that predation by small protozoa is by far the most important cause of bacterial protein turnover in the rumen, with autolysis, other lytic factors and endogenous proteolysis being of minor importance.

1. Adolescent cockerels of a laying strain were prepared with catheters whose tip lay in the hepatic portal vein, to study the effect of 3-h infusions of nutrients on food intake.

2. Lysine, infused into the hepatic portal vein at rates of 150–450 mg/3 h reduced 3-h food intake by up to 58%, for a period of 6 h in previously starved birds, but had no effect on birds allowed free access to food. Infusions made into the jugular vein had no effect, suggesting a role for the liver in monitoring lysine levels.

3. Portal infusion of leucine had a delayed effect while ammonium chloride, infused at isomolar rates to those of the lysine infusions, had very little effect on intake.

4. The results support the concept of liver sensitivity to amino acids, but the mode of action is not clear; it appears not to be via the effects of ammonia.