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Results for “Digestive System Physiological Phenomena”

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At least 145 records · Page 8Linked to original sources
PubMed1987

Secretion of somatostatin and its physiologic function.

Somatostatin, initially described as a growth hormone release-inhibitory peptide 14 amino acids in length, has been shown to be one of a family of related peptides. It is ubiquitous in distribution and versatile as a paracrine factor with a potentially important role in the regulation of gut, pancreatic, and nervous system function in addition to its well-recognized influence on the pituitary secretion of growth hormone and thyroid-stimulating hormone. With the development of new super agonists, it has become possible to manipulate the endocrine milieu, to modify gut, pancreatic, and pituitary function, and in the case of several diseases such as acromegaly, intractable diarrhea, and carcinoid, to make a significant advance in therapy.

Animals↗
PubMed1985

Prostaglandins, thromboxanes and leukotrienes in clinical medicine.

Although prostaglandin research began about 50 years ago, many of the most important advances in understanding the biochemistry, physiology and pharmacology have taken place within the past five to ten years. There is great potential for the extension of this research to the clinical practice of medicine. At this time, the most common interaction that clinicians have with the prostaglandin field is in administering nonsteroidal anti-inflammatory drugs, which function by inhibiting prostaglandins. The uses of these drugs include treating not only inflammation, but also dysmenorrhea, some renal disease, thrombotic diseases and some metabolic disorders. Prostaglandin analogs, with their potent effects on uterine contraction, are in common use in obstetrics. Other analogs, with gastric and duodenal cytoprotective effects are useful in treating peptic ulcer disease. Future benefits from prostaglandin and leukotriene research may include new therapy for inflammatory and hypersensitivity diseases such as asthma, inflammatory bowel diseases and dermatitis.

Animals↗
PubMed1985

Gastrointestinal somatostatin: distribution, secretion and physiological significance.

Somatostatin-like immunoreactivity (SLI) has been found throughout the gastrointestinal tract in all species examined. In the stomach it is mainly present in endocrine-type D-cells whereas in the intestine there is also an extensive distribution in enteric neurones. In all regions of the gastrointestinal tract multiple forms of somatostatin exist. A precursor (prosomatostatin) has been partially sequenced, three forms with 20 (SS-20), 25 (SS-25) and 28 (SS-28) amino acids completely sequenced, and somatostatin-14 (SS-14) demonstrated by radioimmunoassay. Both SS-14 and SS-28 exert a wide range of actions on the gastrointestinal tract and there is strong supportive evidence for a role in the regulation of gastric acid and gastrin secretion, gastrointestinal motility and intestinal transport. Both in vivo and in vitro studies on the secretion of gastric SLI into the vasculature have shown that nutrients initiate the process but that subsequent events are regulated by a complex interplay between hormonal and neuronal pathways. GIP is one of the most potent hormonal secretagogues. In the stomach, acetylcholine, opioid peptides and substance P are probably involved in parasympathetic inhibitory pathways and gastrin releasing peptide in stimulatory pathways. The sympathetic nerves are also stimulatory. Regulation of secretion of intestinal SLI has not been so extensively studied. Although SLI is also found in the gastrointestinal lumen the significance is unclear. Despite these advances the exact route of delivery of somatostatin to its target organs is uncertain and paracrine, endocrine and neural pathways may all be involved.

Animals↗
PubMed2004

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers.

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.

Animal Nutritional Physiological Phenomena↗
PubMed1995

The nutritional significance of endogenous N-losses along the gastro-intestinal tract of farm animals.

In animal production, endogenous protein losses associated with the digestion process are important losses, but difficult to measure. Measuring methods include feeding N-free diets, regression techniques based on amino acid profiles, and separating feed protein and endogenous protein by markers like homoarginine, hydrolysed casein or stable isotopes like 15N. Endogenous losses arise from saliva, digestive enzymes, bile, shedded epithelial cells and mucins and may be extra stimulated by the presence in feeds of antinutritional factors (ANF) such as lectins, trypsin inhibitors (TI), tannins and fibre. The impact of such factors may differ between non-ruminants and ruminants. The magnitude of the effect of the different factors is quantified and some of the consequences for protein deposition and nitrogen losses to the environment are discussed.

Amino Acids↗
PubMed2004

Components of feed efficiency in broiler breeding stock: influence of water intake and gastrointestinal contents.

An experiment was conducted with 3 lines of broilers to evaluate the potential roles of water intake and fill of the gastrointestinal (GI) tract on feed conversion ratio (FCR) as measured in a 1-wk FCR test. Birds were reared to juvenile selection age (41 d) and subsequently selected, with the best 18 to 29% of male chicks placed into cages for FCR testing. Feed and water intake were highly correlated in all lines, with each in turn highly correlated with weight gain on test. Although filling of the GI tract differed between the top and bottom halves of the FCR distribution, FCR as measured and corrected for weight of GI tract contents were highly correlated (r = 0.59 to 0.93). Differences between FCR classes were striking for weight gain, but differences between FCR class groups were subtle for starting weight and feed intake. These subtle differences are difficult to detect in a single generation, but may add up through generations of selection. Based on the results of the current and previous studies, it appears that selection for improved FCR works at multiple levels to improve efficiency of feed conversion in broiler breeding stock.

Animal Feed↗
PubMed1996

Plasma flow and net nutrient flux across gut and liver of cattle fed twice daily.

The objectives of this study were 1) to quantify daily patterns of plasma flow and metabolite flux through portal-drained viscera (PDV) and liver in cattle fed twice daily and 2) to identify an interval for blood sampling that would approximate the average daily plasma flow and nutrient flux values. Data are from three experiments in which multicatheterized cattle were fed at or near ad libitum intake twice daily. Five lactating primiparous Holstein cows (506 kg, fed at 0730 and 1930) ate 17.3 kg DM/d as chopped alfalfa hay:corn grain plus supplement (urea and minerals) 50:50 (Exp 1). Five beef steers (474 kg, fed at 0900 and 2100) ate 8.3 kg DM/d as chopped switchgrass hay:corn grain plus supplement 37:63 (Exp 2). Six beef steers (306 kg fed at 0900 and 2100) ate 6.9 kg DM/d as chopped alfalfa hay (Exp 3). Plasma flow (by dilution of para-aminohippurate) was measured hourly for 24 h. Plasma flows (mean +/- SE) through PDV were 1,264 +/- 147, 538 +/- 56, and 499 +/- 26 L/h for Exp. 1, 2, and 3, respectively. Corresponding liver flows were 1,662 +/- 216, 642 +/- 41, and 591 +/- 30 L/h. The within-animal differences from their respective daily means were estimated as a function of time of day using nonparametric smoothing. Across experiments, PDV and liver flows were above the daily mean from 1200 to 1400, were not different from the daily mean from 1600 to 1700, and were below the daily mean from 1930 to 2130. Metabolites measured were ammonia, urea, alpha-amino N, and glucose. In general, metabolite flux was not different from the average daily mean values between 1200 and 1600. Blood sampling over 12 h or one 12-h feeding cycle is sufficient for daily plasma flow and metabolite flux estimation in cattle fed twice daily.

Ammonia↗
PubMed1993

Manipulation of gastrointestinal nutrient delivery in livestock.

Discussed herein are the constraints of nutrient delivery from the gastrointestinal tract that are placed on postabsorptive synthetic processes in highly selected strains of domestic livestock or livestock treated with growth promotants exogenously or via transgenic manipulation. Emphasis is placed on the discussion of recent advances in the knowledge of the regulation and manipulation of digestion and the absorption by the intestinal epithelium. Slaframine, a muscarinic exocrine secretagogue with a high affinity for the gastrointestinal tract, and epidermal growth factor may have practical potential for the manipulation of digestion and absorption, respectively. Special consideration is given to energetic considerations that must accompany any manipulation of gastrointestinal function. Down-regulation and up-regulation of mechanisms must be equally considered as this area is explored further.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

Histamine H3 receptors: an overview.

Histamine H3 receptors represent a new class of prejunctional receptors, which, first described as modulators of histamine synthesis and release in the central nervous system, were subsequently found to occur also in peripheral tissues. They may behave both as autoreceptors located in histaminergic neurons and as heteroreceptors localized in adrenergic, cholinergic, serotoninergic and NANC nerve endings. As far as the gastrointestinal tract is concerned, H3 receptors seem to negatively control gastric acid secretion induced by endogenous cholinergic stimuli as well as gastrointestinal motility, as observed in different isolated preparations electrically stimulated. So far experimental evidence suggests that these receptors are absent in the effector organs. The most selective agonist and antagonist of H3 receptors are (R) alpha-methylhistamine and thioperamide, respectively; however, a lot of similar compounds are being synthesized in a few laboratories. It is easy to foresee that in the near future the availability of such substances will help the investigators in enlarging our knowledge in this interesting field.

Animals↗
PubMed1986

Potential role of in vitro iron bioavailability studies in combatting iron deficiency: a study of the effects of phosvitin on iron mobilization from pinto beans.

Iron deficiency and iron overload affect one billion people worldwide. Treatment of iron malnutrition can be enhanced by an understanding of iron bioavailability from the diet. We have focused on the development of in vitro methods for determining iron bioavailability in the hopes of providing both an understanding of the chemical basis leading to the inhibition or enhancement of iron absorption and the provision of methodologies which will allow nutritionists around the world to ascertain iron bioavailability of local foods and food combinations. The study reported here focuses on the effects of phosvitin, a suspected inhibitor of iron absorption found in egg yolks, on the chemistry of iron during the in vitro enzymatic digestion of pinto beans. Three basic types of information were obtained. First, the total soluble iron was determined during in vitro enzymatic digestion under simulated oral, gastric (pH 2) and duodenal (pH 6) conditions. Phosvitin was found to have a strong solubilizing effect at pH 6 and pH 2 when in the presence of ascorbate. Pyrophosphate also leads to high iron mobilization. A second approach is to determine the static Fe2+ and Fe3+ concentrations following in vitro enzymatic digestion of pinto beans at pH 2 and pH 6. Ascorbic acid enhanced the total soluble iron at both pH values, however, only at pH 2 was a large proportion of the iron found in the Fe2+ state and then only in the presence of phosvitin but not pyrophosphate. A third approach is to determine the amount of Fe2+ formed in the digestive supernatant during a 10-min incubation with ferrozine.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascorbic Acid↗