Trans-Mucosal Passage of Intact Peptides in the Guinea-Pig Small Intestine in Vivo: A Re-Appraisal

1983 ◽  
Vol 64 (4) ◽  
pp. 433-439 ◽  
Author(s):  
Michael L. G. Gardner ◽  
Bo S. Lindblad ◽  
David Burston ◽  
David M. Matthews
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Chemical Analysis ◽  
Guinea Pig ◽  
Venous Blood ◽  
Amino Nitrogen ◽  
Confidence Limits ◽  
Small Peptides ◽  
Intraduodenal Infusion

1. Re-examination of data for the chemical analysis of peptide-bound amino acids in the mesenteric venous blood of anaesthetized guinea-pigs suggests that there are small, but significant, amounts of small peptides in the blood of fasted animals. 2. Furthermore, there is a significant increase in the peptide content of the mesenteric venous blood during intraduodenal infusion of a partial digest of casein. 3. The data are consistent with the view that some 10% of the amino nitrogen entering the mesenteric blood during absorption of a casein digest in vivo may be in the form of small peptides, although it is not possible to define confidence limits for this estimate.

In vivo and in vitro Absorption of Amino Acids and Dipeptides in the Small Intestine of Uremic Rats

Nephron ◽  
1982 ◽  
Vol 31 (3) ◽  
pp. 273-276 ◽  
Author(s):  
G. Sterner ◽  
T. Lindberg ◽  
T. Denneberg
Keyword(s):  
Amino Acids ◽  
Small Intestine

scholarly journals Amino acid availability: aspects of chemical analysis and bioassay methodology

2003 ◽  
Vol 16 (2) ◽  
pp. 127-141 ◽  
Author(s):  
Paul J. Moughan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Analysis ◽  
Structural Damage ◽  
Human Subjects ◽  
Scientific Evidence ◽  
Hydrolysis Time ◽  
Amino Acid Availability

AbstractIt is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modifiedin vivodigestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ileal-based amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.

scholarly journals The El Tor Biotype of Vibrio cholerae Exhibits a Growth Advantage in the Stationary Phase in Mixed Cultures with the Classical Biotype

2009 ◽  
Vol 192 (4) ◽  
pp. 955-963 ◽  
Author(s):  
Subhra Pradhan ◽  
Amit K. Baidya ◽  
Amalendu Ghosh ◽  
Kalidas Paul ◽  
Rukhsana Chowdhury
Keyword(s):  
Amino Acids ◽  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Competitive Growth ◽  
Small Peptides ◽  
Ileal Loop ◽  
Infant Mouse ◽  
Culture Filtrates ◽  
El Tor

ABSTRACT Vibrio cholerae strains of the O1 serogroup that typically cause epidemic cholera can be classified into two biotypes, classical and El Tor. The El Tor biotype emerged in 1961 and subsequently displaced the classical biotype as a cause of cholera throughout the world. In this study we demonstrate that when strains of the El Tor and classical biotypes were cocultured in standard LB medium, the El Tor strains clearly had a competitive growth advantage over the classical biotype starting from the late stationary phase and could eventually take over the population. The classical biotype produces extracellular protease(s) in the stationary phase, and the amounts of amino acids and small peptides in the late stationary and death phase culture filtrates of the classical biotype were higher than those in the corresponding culture filtrates of the El Tor biotype. The El Tor biotype cells could utilize the amino acids more efficiently than the classical biotype under the alkaline pH of the stationary phase cultures but not in medium buffered to neutral pH. The growth advantage of the El Tor biotype was also observed in vivo using the ligated rabbit ileal loop and infant mouse animal models.

Intestinal nerves and ion transport: stimuli, reflexes, and responses

1985 ◽  
Vol 248 (3) ◽  
pp. G261-G271 ◽  
Author(s):  
K. A. Hubel
Keyword(s):  
Small Intestine ◽  
Ion Transport ◽  
Water Transport ◽  
Sensory Cell ◽  
Venous Blood ◽  
Extracellular Fluid ◽  
Fluid Secretion ◽  
Alkaline Secretion

The effects of extrinsic and intrinsic nerves on ion and water transport by the intestine are considered and discussed in terms of their possible physiological function. Adrenergic nerves enter the small intestine via mesenteric nerves. Adrenergic tone is usually absent in tissues in vitro but is present in vivo. The nerves increase absorption in response to homeostatic changes associated with acute depletion of extracellular fluid. Cholinergic tone that reduces fluid absorption or causes secretion has been detected in the small intestine of humans, dogs, and cats and in the colon of humans. Extrinsic cholinergic fibers generally do not affect ion transport in small intestine but probably do so in colon. Whether peptides liberated in the mucosa affect enterocytes directly is not clear. Studies on humans and rabbits suggest that the role of substance P is minor. The physiological roles of vasoactive intestinal polypeptide (VIP) and somatostatin remain to be defined. Intraluminal factors also affect ion and water transport. Mucosal rubbing, distension, and cholera toxin cause fluid secretion; acid solutions in the duodenum cause alkaline secretion; these stimuli and hypertonic glucose liberate serotonin into the lumen, the mesenteric venous blood, or both. It has been proposed that the enterochromaffin cell is an epithelial sensory cell that responds to noxious stimuli within the lumen by liberating serotonin. The serotonin initiates a neural reflex through a nicotinic ganglion to liberate a secretagogue that acts on the enterocyte. The function of VIP in this proposed reflex is unclear. The variety of intraluminal stimuli that influence epithelial function implies that there is more than one type of epithelial sensory cell (or sensory mechanism). Prostaglandins may mediate the alkaline secretion caused by acid in the duodenum. There may be other effective substances. Although it has been known for years that intraluminal stimuli affect the coordination of smooth muscle functions, it is not known whether similar stimuli also influence salt and water transport as a meal traverses the alimentary canal.

scholarly journals Metabolism of heat-damaged proteins in the rat

1978 ◽  
Vol 40 (2) ◽  
pp. 185-191 ◽  
Author(s):  
C. Shorrock ◽  
J. E. Ford
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Mucosal Barrier ◽  
Rat Small Intestine ◽  
Small Peptides

1. An extract containing ‘unavailable’ small peptides was isolated from an enzymic digest of heat-damaged cod fillet and examined for its influence on uptake of leucine in the rat small intestine, using the everted-sac technique.2. The extract strongly inhibited the uptake of leucine. It had no effect on uptake of glucose or its metabolism to lactate.3. The findings are discussed in relation to the concept (Buraczewski, Buraczewska & Ford, 1967) that the accumulation of ‘unavailable peptide’ material in the intestine, found in rats given heat-damaged protein, might hinder the absorption of amino acids by blocking a mechanism involved in their transport across the mucosal barrier.

Nitrogen-14 SQUID NQR of L-Ala-L-His and of Serine

1994 ◽  
Vol 49 (12) ◽  
pp. 1188-1192 ◽  
Author(s):  
Ulrike Werner-Zwanziger ◽  
Marcia Ziegeweid ◽  
Bruce Black ◽  
Alexander Pines
Keyword(s):  
Amino Acids ◽  
Nuclear Quadrupole Resonance ◽  
Intermolecular Interactions ◽  
Quantum Interference ◽  
Amino Nitrogen ◽  
Resonance Spectroscopy ◽  
Superconducting Quantum Interference Device ◽  
Small Peptides ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract14N nuclear quadrupole resonance spectroscopy, detected with a Superconducting Quantum Interference Device, makes possible the study of nitrogen environments in amino acids and small peptides. The present experiments characterize: 1) the effects of intermolecular interactions upon the amino nitrogen of serine upon cocrystallization of the stereoisomers in a range of concentrations; 2) the changes of the amino and imidazole nitrogen environments brought about by combining L-Alanine and L-Histidine into the dipeptide L-Ala-L-His.

scholarly journals Free amino acids of testes. Concentrations of free amino acids in the testes of several species and the precursors of glutamate and glutamine in rat testes in vivo

1973 ◽  
Vol 132 (3) ◽  
pp. 353-359 ◽  
Author(s):  
Isa K. Mushahwar ◽  
Roger E. Koeppe
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Guinea Pig ◽  
Free Amino Acids ◽  
Free Amino ◽  
Ammonium Acetate ◽  
Testicular Tissue ◽  
Species Variation

Determination of the free amino acid and lactate content of testicular tissue in rat, guinea pig, rabbit, cat, gerbil, hamster, chicken and bullfrog indicates a substantial species variation. Insulin hypoglycaemia and ammonium acetate toxicity changes the concentration of several free amino acids of rat testes. 14C radioactivity from labelled acetate and ethanol is rapidly incorporated into some of the free amino acids of rat testes in vivo, whereas incorporation from [14C]glucose is relatively slow. These results have been compared with those obtained from similar studies with rat brain. In contrast to brain, there is no evidence for glutamate compartmentation in testes.

scholarly journals Digestion rate of dietary starch affects systemic circulation of amino acids in weaned pigs

2010 ◽  
Vol 103 (10) ◽  
pp. 1404-1412 ◽  
Author(s):  
Fugui Yin ◽  
Zhenzhen Zhang ◽  
Ju Huang ◽  
Yulong Yin
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Systemic Circulation ◽  
Serum Concentrations ◽  
Weaned Pigs ◽  
Isoleucine Leucine ◽  
Peak Point ◽  
Dietary Starch

The present study was conducted to evaluate the in vitro and in vivo digestibility of dietary starch and its digestive behaviour on the systemic circulating amino acids (AA) in weaned pigs. Eighteen weanling pigs surgically fitted with a catheter in the jugular vein were randomly assigned to three dietary treatment groups. Sticky rice starch (SRS) was hydrolysed more quickly in vitro (P < 0·05) than maize starch (MS) and resistant starch (RS), and was almost completely hydrolysed within 4 h. The in vivo digestibility of dietary starch in different segments of the small intestine was significantly different. SRS was digested (81·9 %; P < 0·05) in the anterior jejunum, but not more than half of the MS and RS was digested in the same segment of the small intestine. The digestibilities of isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, valine, alanine, aspartate and serine in the SRS group were higher than in the MS group (P < 0·05), and all nutritionally indispensable and dispensable AA in the SRS group were higher when compared with those in the RS group (P < 0·05). The serum concentrations of nutritionally indispensable AA, proline and serine in the three groups were increased to a peak point within 1·5 h postprandially then decreased gradually; however, the time that serum concentrations of alanine, aspartate, glutamate and glycine in each group increased to a peak point was different. The concentrations of nutritionally indispensable AA, including arginine, cystine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 09.30 hours and arginine, cystine, histidine, isoleucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 13.30 hours in the SRS group were higher than in the MS group (P < 0·05); all nutritionally indispensable AA in the SRS group were higher than in the RS group at 09.30 and 13.30 hours (P < 0·05), respectively. We conclude that dietary starches digested rapidly in vitro have higher digestibility in the anterior small intestine of pigs. Diets containing rapidly digestible starch ameliorate the digestive and absorptive function and regulate AA metabolism to beneficially increase the entry of dietary AA into the systemic circulation in pigs.

Avoparcin and monensin effects on the digestion of nutrients in dairy cows fed a mixed diet

1995 ◽  
Vol 75 (3) ◽  
pp. 379-385 ◽  
Author(s):  
D. Ali Haïmoud ◽  
M. Vernay ◽  
C. Bayourthe ◽  
R. Moncoulon
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Control Diet ◽  
Latin Square ◽  
Pronounced Effect ◽  
Glucose Levels ◽  
Ruminal Ph ◽  
Lactating Cows ◽  
Bacterial Protein Synthesis

An in vivo study was carried out to evaluate the effect of avoparcin on fiber, starch and nitrogen (N) digestion compared with monensin. Three dairy lactating cows with ruminal, duodenal and ileal cannulas were used in a 3 × 3 Latin square design. Cows were fed three diets; the control diet had no additive, and the others contained 33 ppm of either avoparcin or monensin-sodium. There were no treatment effects on ruminal pH and total volatile fatty acid levels; molar proportion of propionate tended to be higher (27.9–29.9 vs. 23.7%) and of butyrate tended to be lower (9.9–12.9 vs. 15.4%) for the antibiotic-supplemented diets. Also, both additives decreased ruminal ammonia N concentration (77.2–105.6 vs. 164.1 mg L−1). The supply of avoparcin or monensin reduced the ruminal breakdown of fiber (36.1 and 37.1 vs. 45.9%) starch (57.4 and 54.7 vs. 63.6%), and dietary N (59.5 and 53.6 vs. 67.3%); efficiency of bacterial protein synthesis was unchanged. Passage of bacterial N to the small intestine was not modified; flows of fiber, starch, nonammonia N and dietary N were improved by the both additives. In comparison with the control, monensin caused a greater quantity of glucose (2100 vs. 1500 g d−1) and total amino acids (AA) (1381 vs. 1047 g d−1) to be digested in the small intestine; avoparcin had a less pronounced effect on the intestinal absorption of glucose (1700 g d−1) and AA (1152 g d−1). Only monensin increased the plasma glucose levels (3.6 vs. 3.1 mM). Both additives did not affect total tract digestibilities of organic matter, fiber, starch, and N. Postruminal digestion of fiber was greater (16.0 vs. 7.3%) for antibiotic-supplemented diets, compensating for the lower forestomach digestion. In comparison with monensin dietary avoparcin had a less pronounced effect on the alteration of nutrient digestion. Key words: Avoparcin, monensin, rumen, intestines, amino acids, digestion, cattle

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