https://www.gastrojournal.org/article/S0016-5085(79)91337-4/pdf

Small Intestine Bacterial Overgrowth

Noninsulin-dependent diabetes mellitus (NIDDM) is an increasingly common disease, which brings a number of life-threatening complications. In rats with experimentally induced diabetes, there is an ...

https://www.physiology.org/doi/pdf/10.1152/ajpgi.00310.2001

Expression of monosaccharide transporters in intestine of diabetic humans

Unstirred layer, source of biased Michaelis constant in membrane transport.

Publisher Summary This chapter discusses interaction of helminths and their hosts within the alimentary canal and, especially the stomach and intestines. Many such parasites live in the gastro-intestinal canal while others penetrate into the wall of the canal and a few invade organs, such as the liver and pancreas. The dynamic relationship between parasite and host is clearly shown and a good example set for future researchers. First, there is a study of the parasite–host interface, including the various kinds of organs of attachment, the varied nature of the lumen and the mucosa of the gastrointestinal canal, the nature of adhesion, and absorptive surfaces of the helminth and the host. The chapter describes the ecology of helminth site selection by trematodes, cestodes, and nematodes and matters concerning concurrent infections, transplantation, and migration. The chemical and physical characteristics of the intestinal lumen ionic and osmotic characters, microbial ecology, enzymes, bile acids and dietary fats, nutritive gradients, and matters of luminal homeostasis are discussed. The functional gradients in the gastrointestinal tract, bearing on the absorption of electrolytes and nonelectrolytes, water absorption, and malabsorption are also discussed.

Ecological and Physiological Aspects of Helminth-Host Interactions in the Mammalian Gastrointestinal Canal

Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.

/pdf/glucose-transporters-in-the-small-intestine-in-health-and-bt55c0vkbv.pdf

Glucose transporters in the small intestine in health and disease

Die Fahigkeit des Dunndarms, die Resorptionskapazitat unter bestimmten Belastungen kompensatorisch zu vergrosern, ist bekannt. Andererseits fehlen Untersuchungen zum Verhalten der Dunndarmschleimhaut nach partiellem Ausschlus aus der Passage, bei dem mit einem gegensinnigen Anpassungsvorgang zu rechnen ware. In der vorliegenden Arbeit wurde der Einflus einer „Inaktivierung“ durch eine segmentale Ausschlusoperation auf die Jejunalschleimhaut der Ratte morphologisch, morphometrisch, histochemisch und mit Hilfe von Transportstudien untersucht, um dieser Frage nachzugehen.

Transportstudien, morphologische, morphometrische und histochemische Untersuchungen zum Verhalten der Dünndarmschleimhaut im operativ ausgeschalteten Jejunalabschnitt der Ratte

Twenty days after the onset of alloxan-induced diabetes, a villous hyperplasia has developed in the intestines of rats having free access to food. The transformation is characterised by a considerable increase in the area of the villous surface, caused by an enhanced mitotic activity in the crypts. The absorption of glucose or methionine by jejunal loops, whether expressed in terms of serosal area or villous area, is unchanged at this stage. On the other hand, the specific activity of certain disaccharidases and dipeptidases in crude mucosal homogenates is greater in diabetic animals, but quantitative histochemistry revealed no changes in the activities of alkaline phosphatase, leucine amino-peptidase and non-specific esterase in the individual enterocytes. Thus the biochemical changes may simply reflect the hyperplasia of the mucosa. The blood sugar level does not appear to be directly responsible for the mucosal transformation; however, the positive correlation between the daily food intake and the villus height suggests a role of hyperphagia and consequent increased luminal nutrition in the development of the hyperplasia.

Structural and functional studies on the transformation of the intestinal mucosa in rats with experimental diabetes

In rat self-filling blind loops and in the contiguous regions of the intestinal tract, considerable functional impairment, accompanied by pronounced morphological transformations of the mucosa, has been observed. The histological alterations consist of mucosal hypertrophy and a reduction in the villus height: crypt length ratio, which is indicative of a hyper-regenerative change. Various enzyme activities of the epithelial cells are reduced and the absorption of octanoate in vivo is diminished. The ratio of free: conjugated bile acids in the intestinal juices is greatly altered in favour of the free acids. Two mechanisms have been discussed in relation to the observed mucosal changes: 1. A direct effect of the free bile acids, or metabolites from bacterial degradation, on the absorptive epithelium; 2. Reduced cellular maturity in response to the effect of bile acids and/or bacteria on the lifespan of the cells.

Functional, biochemical and morphological alterations in the intestines of rats with an experimental blind-loop syndrome.

An weiblichen Wistarratten wurden die zellularen und strukturellen Veranderungen der Dunndarmschleimhaut nach chronischer MS-Belastung durch 12tagige Dauerinfusion ins Jejunum untersucht. Folgende Befunde wurden erhoben:

1.

Die MS-Belastung fuhrt in Abhangigkeit von der Konzentration zur Reduktion des Glukosetransports.




2.

Die Funktionsstorung ist bedingt durch Enzymaktivitatsverlust.




3.

Die Reduktion betrifft alle enzymhistochemisch untersuchten Aktivitaten; sie zeigt, das alle Zellkompartimente des Epithels beeintrachtigt sind.




4.

Qualitative Abweichungen des Reaktionsmusters treten nach MS-Belastung nur beim Saure-Phosphatase-Nachweis auf. Sie sind gekennzeichnet durch Schwund der Markierbarkeit lysosomaler Granula und Auftreten einer schwachen, diffusen cytoplasmatischen Aktivitat.




5.

Die Schleimhaut unterliegt einer von der MS-Konzentration abhangigen Transformation mit Verschiebung der Zottenhohen und Kryptentiefen. Sie wird begleitet von einer gesteigerten mitotischen Aktivitat als Folge erhohter Zellexfoliation an der Zottenspitze. Es handelt sich bei dieser Veranderung somit um eine Schleimhauttransformation vom hyper-regeneratorischen Typ. Ihr Initialstadium ist eine Hypertrophie, ihr Endstadium die zottenlose Schleimhaut mit stark veranderten Krypten. Das Endstadium wird unter MS-Belastung nicht ausgebildet, da geringe Konzentrationssteigerungen zu lokaler Gewebsschadigung und Darmperforation fuhren.




6.

Das MS-Modell ist wegen seiner geringen experimentellen Breite ungeeignet fur die biochemische Nacharbeitung der bei der einheimischen Sprue beobachteten cytochemischen Epithelveranderungen.

Morphological and functional findings after prolonged lactic acid perfusion of the small intestine in the rat

In der vorliegenden Studie wird erstmalig der Einflus von Phenformin (25 mg/kg Ratte) auf die Wasser- und Elektrolytresorption an der Ratte untersucht. Im Hinbliek auf die an Leber- und Nierenmitochondrien nachgewiesene Hemmung der oxydativen Phosphorylierung durch Biguanide wird weiterhin der Einflus des Phenformins auf die Adeninnucleotide des Rattendunndarms gepruft. Zur Frage nach der cellularen und mukosen Integritat der Dunndarmschleimhaut unter Phenformin werden cytochemische und morphometrische Untersuchungen angestellt. Daruber hinaus wird die Glucoseresorption mittels kontinuierlicher in vivo-Perfusion gemessen. Zur Frage der physiologischen Relevanz der an der Ratte durchgefuhrten Untersuchungen wird die Glucoseresorption am Menschen mittels der dreilumigen Sonde bei physiologischer Phenforminbelastung (150 mg/d) gepruft.

H. Menge

Papers

Transportstudien, morphologische, morphometrische und histochemische Untersuchungen zum Verhalten der Dünndarmschleimhaut im operativ ausgeschalteten Jejunalabschnitt der Ratte

Structural and functional studies on the transformation of the intestinal mucosa in rats with experimental diabetes

Functional, biochemical and morphological alterations in the intestines of rats with an experimental blind-loop syndrome.

Morphological and functional findings after prolonged lactic acid perfusion of the small intestine in the rat

Biochemische, histochemische, histologische und funktionelle Untersuchungen zur Phenforminwirkung auf die Dünndarmschleimhaut bei Ratte und Mensch