Intestinal Protein Content Research Articles

Acute actions of 1,25-dihydroxyvitamin D 3 upon chick pancreatic calbindin-D 28K

We have compared the relative responsiveness of pancreatic, intestinal and renal tissue calbindin-D 28K protein content to the stimulatory actions of 1,25-dihydroxyvitamin D3 [1,25(OH) 2D 3] in vitamin D-deficient (-D) chicks. Tissue concentrations of calbindin-D 28K were undetectable in the -D chick intestine but present, albeit at low concentrations (<1μg CaBP/mg protein) in the -D kidney and pancreas. Intestinal, pancreatic and renal calbindin-D 28K content was stimulated 318, 9.8 and 2.9 fold respectively, 48 hours after -D chicks received a single dose of 1,25(OH) 2D 3 [6.5 nmole/animal]. The pancreatic calbindin-D 28K content could be significantly stimulated as early as 5 hours after 1,25(OH) 2D 3 administrations in vivo . These findings support the contention that the pancreas is a target for vitamin D, and is consistent with the view that calbindin-D 28K plays a role in normal pancreatic functions.

Glutamine or Glutamic Acid Effects on Intestinal Growth and Disaccharidase Activity in Infant Piglets Receiving Total Parenteral Nutrition

This study was designed to measure the effect of free glutamine or glutamic acid supplementation on small intestinal growth and disaccharidase enzyme activity in 7-day-old miniature piglets. The piglets received one of three total parenteral nutrition solutions exclusively for 7 days. All three solutions were isonitrogenous and isocaloric, and glutamine or glutamic acid was included at physiological levels (5% of the total amino acid content) in two of the three solutions; the third (control) contained neither glutamine nor glutamic acid. No differences were seen between groups in plasma glutamine or glutamic acid concentrations. Similarly, no effect was observed on small intestinal protein or DNA content or on the specific activities of lactase, sucrase, or maltase. These data demonstrate that in the healthy miniature piglet, parenteral glutamine or glutamic acid supplemented at physiological doses does not influence small intestinal growth and development.

Performance of lactating simmental cows fed two diets differing in the content of digestible intestinal protein (PDI)

In each of two trials, two diets differing in intestinal digestible protein (PDI) content (LP: low protein, 70 g kg −1 dry matter; HP: high protein, 120 g kg −1 dry matter) were given to multiparous Simmental cows in early lactation. Effective rumen degradabilities of nitrogen and non-protein dry matter of feed ingredients, estimated by the nylon-bag technique, were used to calculate PDI contents of diets. In trial 1, two groups of six cows were fed, in two successive periods of 7 weeks each, the diets LP and HP allocated according to energy requirements (LPR and HPR). In trial 2, the diets LP and HP were fed in two periods of 6 weeks each to 24 cows (six cows/group) according to energy requirements (LPR and HPR) or ad libitum (LPL and HPL). In trial 1, total and energy-corrected milk (ECM) yields were significantly higher (P < 0.01) for cows receiving diet HPR (20.7 and 19.2 vs. 18.9 and 17.4 kg day −1), while milk fat and protein contents were similar. Live weight changes were different between groups (−126 and +39 g day −1 respectively, for LPR and HPR diets) but this difference was not significant. In trial 2, cows fed HPL diets had significantly higher milk yields compared with the LPL and LPR diets (20.0 vs. 17.7 and 17.4 kg day −1, respectively, P < 0.05), but not with the HPR diet (19.0 kg day −1). ECM yield was higher (P < 0.05) for cows receiving more protein both between restricted groups (18.4 vs. 16.4 kg day −1, respectively for HPR and LPR groups) and between ad-libitum groups (18.8 vs. 17.0 kg day −1, respectively for HPL and LPL groups). Milk composition was not affected by dietary treatments. Diets fed according to requirements caused negative, but differing, live weight changes (−783 and −44 day −1 respectively for LPR and HPR diets, P < 0.05). For ad-libitum treatments, LPL cows lost live weight while HPL cows gained live weight (−221 vs. 433 day −1, respectively, P < 0.05). In the present experiments, increasing the supply of dietary PDI improved milk production even if the recycled nitrogen and live weight change could have contributed to protein requirements.

Effect of Dietary Nucleotides on Intestinal Repair in Rats with Experimental Chronic Diarrhea

Nucleic acid synthesis in tissues of rapid growth is preferentially done using dietary purines and pyrimidines via the salvage pathway. In the case of a low protein intake, dietary nucleotides may be semiessential for cell replication of gut, lymphocytes, and bone marrow, and especially in those intestinal diseases in which the mucosa is altered, dietary nucleotides may have a role in intestinal development. The effect of dietary nucleotides on intestinal weight and length, gut mucosal weight, intestinal protein and DNA contents, and lactase, maltase, and intestinal mucosal activities was assessed in a controlled way. Weanling (21-day-old) rats were separated into two groups of 36, each receiving blindly a basal diet containing glucose polymers (C) or a basal diet with lactose as the main carbohydrate (L) for 15 days. Those fed with L developed a syndrome of chronic diarrhea and malnutrition. Ten rats of each group were sacrificed at that time. The rest of the animals of each group were separated into two subgroups. The first was fed with the C diet and the second with the C diet supplemented with 50 mg/100 g of each of the following nucleotides: AMP, GMP, CMP, UMP, and IMP (CN). Thus the subgroups CC, CN, LC, and LN were formed. Rats were sacrificed after 4 weeks and gut separated into three segments corresponding to duodenum, jejunum, and ileum. Analysis of variance was used to compare the effect of diet or segments. DNA and lactase, maltase, and sucrase activities increased in the LN group with respect to LC especially in jejunum and ileum but there were not any differences between CC and CN.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Zinc‐Deficient Diet of Varying Duration on Intestinal Disaccharidase Activity in the Rat

To determine whether zinc has a specific role on weight gain and intestinal disaccharidase activity, 42 male Sprague‐Dawley rats were assigned to one of seven groups (n =6 each). These were a baseline control group (O) that was killed to analyze initial intestinal disaccharidase (sucrase and maltase) activity, a second group (A) fed a zinc‐deficient diet for 1 week, a third group (B) pair‐fed control for A, a fourth group (C) fed a zinc‐deficient diet for 2 weeks, a fifth group (D) pair‐fed control for C, a sixth group (E) fed a zinc‐deficient diet for 3 weeks, and a seventh group (F) pair‐fed control for E. All experimental groups received distilled deionized drinking water, whereas control groups received zinc‐enriched (25 μg of zinc/ml) distilled deionized water. Water was given ad libitum. After killing, the mucosa of the proximal half of the small intestine was analyzed for protein and disaccharidase activity, and liver, kidney, and heart were analyzed for zinc concentration. Protein content and disaccharidase activity of the jejunal mucosa in the experiment and control groups did not differ significantly. However, animals on the zinc‐deficient diet demonstrated mildly depressed growth rates that were proportional to the duration of the experiment, and significantly lower zinc concentration in the kidney in the experimental groups. The data indicate that administration of a zinc‐deficient diet for up to 3 weeks did not result in significant changes in intestinal mucosa protein content or in disaccharidase activity.

Effect of Zinc-Deficient Diet of Varying Duration on Intestinal Disaccharidase Activity in the Rat

To determine whether zinc has a specific role on weight gain and intestinal disaccharidase activity, 42 male Sprague-Dawley rats were assigned to one of seven groups (n = 6 each). These were a baseline control group (0) that was killed to analyze initial intestinal disaccharidase (sucrase and maltase) activity, a second group (A) fed a zinc-deficient diet for 1 week, a third group (B) pair-fed control for A, a fourth group (C) fed a zinc-deficient diet for 2 weeks, a fifth group (D) pair-fed control for C, a sixth group (E) fed a zinc-deficient diet for 3 weeks, and a seventh group (F) pair-fed control for E. All experimental groups received distilled deionized drinking water, whereas control groups received zinc-enriched (25 micrograms of zinc/ml) distilled deionized water. Water was given ad libitum. After killing, the mucosa of the proximal half of the small intestine was analyzed for protein and disaccharidase activity, and liver, kidney, and heart were analyzed for zinc concentration. Protein content and disaccharidase activity of the jejunal mucosa in the experiment and control groups did not differ significantly. However, animals on the zinc-deficient diet demonstrated mildly depressed growth rates that were proportional to the duration of the experiment, and significantly lower zinc concentration in the kidney in the experimental groups. The data indicate that administration of a zinc-deficient diet for up to 3 weeks did not result in significant changes in intestinal mucosa protein content or in disaccharidase activity.

Reversibility of the effects of gossypol acetic acid, an antispermatogenic/antifertility agent on the intestinal structure and functions of male albino rats.

The effects of Gossypol acetic acid (10 mg/kg b. wt. daily for 15 days), an experimental male antifertility agent and its subsequent withdrawal for another 15 days, on the structure and functions of the rat small intestinal tract have been investigated. Gossypol feeding causes a reduction in body weight and intestinal weight, length, protein, and nucleic acid contents. A 27%-50% reduction in the uptake of glucose, alanine, leucine, and calcium is observed after Gossypol feeding which is found to be reversible after 15 days of withdrawal of the drug. Gossypol also causes a significant reduction in the activities of sucrase, lactase, maltase and alkaline phosphatase in the intestinal homogenates as well as in the purified brush border membrane of the microvillus. A decrease in the maximum of apparent enzyme velocity and no change in the substrate affinity constant in these digestive hydrolases are observed on Gossypol treatment. It also causes a shift in the transition temperature in these enzymes and predictably changes the energy of activation both below and above the temperature of transition, although the Arrhenius expression of the temperature dependence still shows proximity, non-linearity, and is parallel to the control group. These changes are reversed on withdrawal of the drug and during the subsequent recovery period. Recovery experiments also show near identical values in kinetic parameters (Kt and Jmax) of 14C-glucose uptake in jejunal segments both in the presence and absence of Na+ ions. Also, no difference is observed between the control and recovery groups with respect to body and intestinal weight, intestinal length, and DNA, RNA, protein, lactate dehydrogenase and glucose-6-phosphate phosphohydrolase values in the intestinal homogenates. Phospholipid, cholesterol and sialic acid levels in both the groups also show nearly identical values. Molecular mechanism of the effects of Gossypol on brush border membrane-bound enzyme/carrier molecules operation is discussed in view of the kinetic and thermodynamic data obtained.

Dietary fiber and energy balance: Integration of the human ileostomy and in vitro fermentation models

The metabolizable energy (ME i) contents of 10 diets containing from 13 to 42 g dietary fiber day −1 were calculated by application of the Merrill and Watt specific factors for protein, fat and total carbohydrate in the Atwater system and fed to an ileostomate. Upper intestinal absorption of protein, fat and carbohydrate was measured by difference between intake and ileal output. Apparent upper intestinal digestibilities of protein, fat and available carbohydrate were extremely uniform for all diets except oat bran and kidney beans. The energy absorbed from the upper intestine (ME a) was calculated from the amount of protein, fat and carbohydrate absorbed using 4.55, 9.3 and 4.2 (kcal g −1 nutrient absorbed), respectively. The depressed ME a on the high-fiber diets reflected the increased energy content of the fiber in the ileal digesta and it appeared that dietary fiber did not impair upper intestinal absorption of ME. From in vitro fermentations of ileal digesta, it was predicted that 3–11% of the ME i could potentially be available from the colon in the form of SCFA (AE). The net metabolizable energy (NME=ME a+AE) was within 1% of the Merrill and Watt estimates (ME i) with a correlation coefficient of 0.99 ( P < 0.01). It is concluded that the combination of the ileal model and in vitro simulations of the colonic fermentation is a useful technique to study the effect of dietary fiber on energy balance. It is suggested that the colonic fermentation of dietary fiber can significantly alter the site of energy absorption and human metabolism.

Circadian variation in intestinal protein content in rat fed ad libitum.

The circadian variation in protein content in the digestive tract was studied in parallel with food intake in the free-feeding rat maintained under a 12:12 hr light:dark cycle (lights on at 07 hr). Rate of ingestion of a casein-based diet increased progressively during daytime, but most of the intake occurred in the dark. Gastric emptying of proteins lagged by a 3-hr interval behind intake. N content in the intestine divided equally into three segments also increased in the dark. The rise was specific for each segment with the most marked rise in the second segment. Endogenous N levels were high and accounted for at least two thirds of intestinal N levels. There was no net absorption of N in the first intestinal segment due to dilution by endogenous proteins. Absorption was at an average of 70% in the second segment and reached 85% in the distal intestine. The amino acid composition of intestinal protein content reflected endogenous proteins much more than casein. Specific trypsin activity increased distally. The appearance of nitrogenous material (alpha-amino N) in portal blood also followed a circadian variation reflecting the pattern of food intake. In spite of their high level in the intestine, endogenous proteins did not lead to an appreciable appearance of nitrogenous material in the blood except at 10 hours. Results indicate that fluctuation in food intake is accompanied by complex variations in protein contents of the digestive tract. Endogenous protein levels were high and seemed to have a slow turnover.

Effect of Urogastrone/EGF on Shall Intestinal Weight, Protein Content and Brush Border Enzyme Activities in Parenterally-Fed (TON) Rats

Conference Abstract| December 01 1988 Effect of Urogastrone/EGF on Shall Intestinal Weight, Protein Content and Brush Border Enzyme Activities in Parenterally-Fed (TON) Rats K.B. Raja; K.B. Raja 1Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex and Department of Histopathology, Royal Postgraduate Medical School, London, UK Search for other works by this author on: This Site PubMed Google Scholar R.A. Goodlad; R.A. Goodlad 1Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex and Department of Histopathology, Royal Postgraduate Medical School, London, UK Search for other works by this author on: This Site PubMed Google Scholar N.A. Wright; N.A. Wright 1Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex and Department of Histopathology, Royal Postgraduate Medical School, London, UK Search for other works by this author on: This Site PubMed Google Scholar W. Lenton; W. Lenton 1Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex and Department of Histopathology, Royal Postgraduate Medical School, London, UK Search for other works by this author on: This Site PubMed Google Scholar T.J. Peters T.J. Peters 1Division of Clinical Cell Biology, MRC Clinical Research Centre, Harrow, Middlesex and Department of Histopathology, Royal Postgraduate Medical School, London, UK Search for other works by this author on: This Site PubMed Google Scholar Clin Sci (Lond) (1988) 75 (s19): 50P. https://doi.org/10.1042/cs075050Pb Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation K.B. Raja, R.A. Goodlad, N.A. Wright, W. Lenton, T.J. Peters; Effect of Urogastrone/EGF on Shall Intestinal Weight, Protein Content and Brush Border Enzyme Activities in Parenterally-Fed (TON) Rats. Clin Sci (Lond) 1 December 1988; 75 (s19): 50P. doi: https://doi.org/10.1042/cs075050Pb Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsClinical Science Search Advanced Search This content is only available as a PDF. © 1988 The Biochemical Society and the Medical Research Society1988 Article PDF first page preview Close Modal You do not currently have access to this content.

Interaction of neurotensin with caerulein or secretin on digestive tract growth in rats

Because neurotensin may potentiate exocrine pancreatic secretory responses to cholecystokinin and secretin, we examined interactions of neurotensin with caerulein or secretin on growth of pancreas, stomach, small intestine, and colon. Rats were injected with saline, neurotensin (100 μg/kg), caerulein (0.67 μg/kg), secretin (100 μg/kg), or neurotensin plus caerulein or secretin every 8 h for 5 days. Pancreas, stomach, small intestine, and colon were weighed and assayed for DNA, protein, and digestive enzymes. Although neurotensin increased pancreatic weight ( P < 0.01), DNA ( P < 0.01), and protein content ( P < 0.05) by 20–30%, it had less than additive effects on responses to caerulein and secretin. Neurotensin had no effects on pancreatic enzymes or on responses to caerulein or secretin. Neurotensin alone had no effects on growth of the oxyntic gland area or antrum but inhibited increases in antral weight, DNA, and protein caused by secretin. Neurotensin increased small intestine weight (9%, P < 0.05) and protein content (23%, P < 0.01). Secretin also increased weight (22%), DNA (29%), and protein content (48%) of the small intestine (all P < 0.01), but neurotensin and secretin together had less than additive effects. Our results suggest that neurotensin inhibits rather than potentiates certain growth effects of caerulein or secretin on the pancreas and other organs.

Effect of different total parenteral nutrition fuel mixes on small intestinal growth and differentiation in the infant miniature pig

Insulin has been proposed as an important factor in the regulation of growth and differentiation of the small intestine. In the newborn miniature pig, we induced significant physiologic increases in serum insulin and the insulin/glucagon ratio without altering serum glucose, β-hydroxybuterate, glucagon, cortisol, T3, and T4 using glucose-based total parenteral nutrition (TPN) in one group (group G) compared with a combination of glucose and fat in another group (group G/F). Control animals were sham-operated and fed a pelleted diet (group OC). Duodenal villus surface area and mucosal height were significantly greater in group G/F compared with group G. No other differences between the TPN groups were found in small intestinal growth, mucosal protein, deoxyribonucleic acid and ribonucleic acid content, and disaccharidase activities. As anticipated, group OC demonstrated increased intestinal length, weight, and villous surface area compared with the TPN groups. Ileal sucrase and jejunal and ileal maltase activities were greater in the TPN groups compared with those in group OC. Physiologic changes in serum insulin and the insulin/glucagon ratio induced by the TPN fuel mix do not appear to have altered small intestinal growth, composition, and differentiation in the healthy small intestine.

Glucagon inhibition of cerulein-induced hypertrophy of the exocrine pancreas.

Glucagon is structurally related to secretin but inhibits the effects of secretin and cholecystokinin (CCK) on pancreatic secretion in vivo. Because secretin is a weak stimulant of pancreatic growth and potentiates the trophic effects of CCK, we hypothesized that glucagon might inhibit CCK-induced pancreatic growth. Four groups of 10 rats were injected with saline, glucagon (30 micrograms/kg, equimolar to a known trophic dose of secretin), cerulein (0.67 microgram/kg), or glucagon plus cerulein every 8 h for 5 days. The pancreas was excised, weighed, and assayed for total content of DNA, protein, amylase, chymotrypsinogen, and lipase. In control and glucagon-alone groups, the small intestine was also removed, weighed, and assayed for DNA, protein, and disaccharidase content. Glucagon alone decreased pancreatic DNA and increased lipase content. Compared with cerulein-treated animals, animals treated with glucagon and cerulein showed significant decreases in pancreatic weight and content of protein, amylase, and chymotrypsinogen. Although glucagon had significant effects on intestinal protein, maltase, and sucrase contents in certain segments, there was no clear pattern of response. The data suggest that glucagon may be an inhibitory regulator of pancreatic growth, acting to block the effects of CCK on pancreatic hypertrophy.

Effects of enterally fed epidermal growth factor on the small and large intestine of the suckling rat.

Epidermal growth factor (EGF) has been shown to be present in the milk of several species, including the rat, and to have gastrointestinal effects when given parenterally or orally in pharmacologic doses. We investigated the effect of enteral EGF in physiologic doses on the small intestine and colon of suckling rats. Serum thyroxine (T4) levels were also measured. Rats were gavage-fed by hand with an artificial formula with or without added EGF every 3 h from 11 to 14 days of age. Intake was adjusted to deliver 30 kcal/100 g b.wt./day of formula and 16 micrograms/kg/day of EGF approximating the daily caloric intake, and about twice the estimated daily EGF intake for suckling rats. Weight gain did not differ between groups (fed EGF: 3.8 + 0.2 g; not fed EGF: 3.7 + 0.1 g). The protein content of the whole colon of rats fed an EGF-containing formula was significantly lower and the DNA content significantly higher, than in rats fed formula without added EGF. The protein/DNA ratio was therefore markedly higher in the animals fed formula without added EGF; these effects were most evident in the distal colon. In contrast, there was no effect of EGF on small intestinal protein and DNA content; lactase, sucrase, and maltase activities were likewise unaffected, as was serum T4. These data suggest a physiologic role for breast milk EGF in the development of the suckling rat colon.

Influence of protein composition and hydrolysis method on intestinal absorption of protein in man.

An intestinal perfusion technique has been used in normal human subjects to investigate the influence that starter protein composition and hydrolysis procedure have on absorption of amino acid residues from partial enzymic hydrolysates of whole protein. Five starter proteins were studied. Three (egg albumin, casein/soy/lactalbumin, and lactalbumin) were hydrolysed by papain, a second lactalbumin starter protein, and a meat/soy/lactalbumin blend were hydrolysed by a porcine pancreatic enzyme system. Irrespective of starter protein composition or hydrolysis method used, four amino acid residues (threonine, glutamic acid, phenylalanine, and histidine) were absorbed significantly faster from all hydrolysates compared with absorption from their equivalent free amino acid mixtures. In contrast, both starter protein composition and hydrolysis method influenced absorption characteristics of up to nine other amino acid residues.

625 ROLE OF ENTERAL NUTRIENTS IN INTESTINAL MATURATION

Dramatic maturational changes in gastrointestinal function occur in rats during the 3rd week of life. Because the role of enteral nutrients in these changes in unclear, we investigated the effects of enteral and parenteral feedings in 14-15 day-old rats that were equipped with either intravenous (IV) or intragastric (IG) cannulas and provided identical amounts of nutrients. A comparison (C) group consisting of age and litter-matched animals allowed to wean normally were used. At 21 days, we measured intestinal length, mucosal weight, disaccharidase activities, DNA and protein content. Intestinal length varied significantly among the 3 groups C>IG>IV (p<.05) while total mucosal weight was comparable in C and IG, but significantly less in IV (p<.05). Total mucosal lactase activity, DNA and protein content did not differ among the 3 groups while total sucrase and maltase activities were highest in IG (p<.05) but comparable in C and IV. Ileal lactase-specific activity (S.A.) was .82±.43 UE/mg DNA in IV compared with .47±.24 for both C and IG (p<.05). Jejunal sucrase S.A. in IG was twice that of the other 2 groups (p<.05) while jejunal maltase S.A. was elevated in both IG and IV compared with C (p<.05). Conslusions: 1) Intestinal maturation is altered by the presence and composition of enteral nutrients during a critical period in GI development. 2) The effect of the altered maturation differs between the 3 disaccharidases suggesting independent developmental mechanisms.

Plasma levels of 3-methylhistidine after ingestion of the pure amino acid or of muscular proteins measured by radioimmunoassay

A radioimmunoassay for plasma 3-methylhistidine (3MeHis) measurements has been developed. The assay has no significant crossreactivity with 18 other amino acids including histidine, carnosine, anserine, and creatinine. In normal subjects who have eaten no meat for 36 hours, plasma levels are constant over a 24-hour period (8.78 ± 0.48 μmol/L, mean ± SD). The use of 3MeHis for the assessment of intestinal protein absorption and its potential use as a marker of protein degradation were evaluated by studying its plasma kinetics. The absorption of the free 3MeHis is rapid and reaches a peak after 75 minutes. The peak is delayed after meat ingestion and reaches a maximum after 180 minutes. The ratio of the 75- to 180-minute 3MeHis levels was 1.40 ± 0.06 for pure 3MeHis and 0.78 ± 0.06 after meat ingestion ( P < 0,001). Peak height and area under the plasma concentration versus time curve were proportional to the dose received, indicating first order kinetics for 3 MeHis. It has a half-life of 12.2 hours, a metabolic clearance rate of 0.08 L/h and volume of distribution is 11.7 ± 1.7 L as calculated from the serum values which were obtained up to 24 hours after oral 3MeHis administration. Its endogenous production can therefore be calculated to be 116 μmols per day in young subjects. Thus, the radioimmunoassay develops the potential of this amino acid as a marker of protein degradation and absorption for physiological investigations.

Effects of ethanol on cytoplasmic peptidases of the jejunal epithelial cell of the hamster.

Although ethanol has been reported to inhibit intestinal amino acid absorption and peptide hydrolysis by the brush border membrane (BBM) peptidases, its effect on other events of protein absorption (such as peptide hydrolysis by cytosol peptidases, absorption of peptides across the BBM, and translocation of amino acids across the basolaterial membrane) has not yet been reported. To obtain a better understanding of the overall effect of ethanol on intestinal protein absorption, in the present study we have investigated the influence of ethanol on the cytosol peptidases. In order to examine the activity of these enzymes, without the influence of brush border digestion and translocation of peptides, the present study was carried out in vitro using a preparation of cytosol peptidases. Results show that exposure of the enzymes to 1-5% (w/v) ethanol caused a dose-dependent inhibition of hydrolysis of L-leucylglycine (Leu-Gly), glycyl-L-tyrosine (Gly-Tyr), and L-phenylalanylglycine (Phe-Gly) by the cytosol peptidases. These inhibitions were completely reversible. Kinetic studies indicated that ethanol depressed the hydrolysis of Leu-Gly and Gly-Tyr by a mixed type of inhibition, in which the Vmax decreased and the Km increased. In the hydrolysis of Phe-Gly, two enzymes were involved, and ethanol depressed the Vmax of both, without affecting their Km. These findings suggest that ethanol alters only the catalytic center of both enzymes involved in the hydrolysis of Phe-Gly and alters both the catalytic center and the substrate binding site of the enzymes involved in the hydrolysis of Leu-Gly and Gly-Tyr. The results of this study together with those of our previous investigation on BBM peptidases indicate that ethanol interferes with the intestinal hydrolysis of peptides and, therefore, probably with the absorption of protein.

Transfer of gamma-glutamyltransferase from mother colostrum to newborn goat and foal.

In goat and mare colostrum, gamma-glutamyltransferase (GGT) activity is relatively low (mean values are, respectively, 900 and 350 U/l). In the serum of newborns before suckling, GGT is also low (less than or equal to 28 U/l in goats and less than or equal to U/l in foals); then in goats GGT is much increased on the 1st day (mean = 127 U/l), and it decreases during the following days. In foals, serum GGT slowly but regularly increases for the first 5 days, then decreases. Such differences can be attributed to intestinal protein absorption capabilities which are selective in newborn foals and unselective in goats. Therefore, serum GGT measurement can be a good test of colostrum intake in newborn goats, but not in foals.

Early weanling and precocious development of small intestine in rats: genetic, dietary or hormonal control.

Small intestinal development was followed in rats from 17 to 28 days of age in order to evaluate the interactions of diets, genetic preprogramming, and hormones in influencing developmental changes. Control pups, weaned naturally at 21-24 days, showed a gradual increase in body weight, intestinal length, and segmental mucosal weight, total DNA, and protein content. In contrast, pups weaned at 17 days showed an immediate increase in intestinal length, decrease in lactase, and precocious increase in sucrase and maltase. The changes in segmental mucosal weight, DNA and protein contents, however, paralleled that of controls. Pups nursed up to 25 days had a smaller body weight, shorter intestine, lighter mucosa, and lesser mucosal protein content. They showed no significant delay in the increase in sucrase and maltase together with a persistent higher level of lactase. Enterokinase and leucine aminopeptidase showed little change irrespective of the dietary modifications. Significant increases in segmental mucosal mass, DNA, and protein contents during the studied period were seen in all animals. At 19 days, early weaned pups had serum levels of corticosteroids about 3 times that of control or prolonged nursed pups. The results support the concept of an inherent biologic program as a basic control of intestinal ontogeny whereas dietary changes seem to have a modifying role and act directly, or in concert with, hormonal changes.