Large intestinal resection induces changes in human colon: study of H+/oligopeptide cotransporter 1 (PepT1), Na+/H+ exchangers 3 and 2 (NHE 3 and NHE 2) and intestinal microbiota - Volume 67 Issue OCE5

The expression of the colonic mitochondrial 3-hydroxy 3-methyl glutaryl CoA (mHMGCoA) synthase, a key control site of ketogenesis from butyrate, is lower in germ-free (GF) than in conventional (CV) rats. In contrast, the activity of glutaminase is higher. The objective of this study was to investigate whether the intestinal flora can affect gene expression through short chain fatty acid (SCFA) and butyrate production. GF rats were inoculated with a conventional flora (Ino-CV) or with a bacterial strain producing butyrate (Clostridium paraputrificum, Ino-Cp) or not (Bifidobacterium breve, Ino-Bb). In the Ino-CV rats, mHMGCoA synthase expression was restored to the CV values 2 days after the inoculation, i.e. concomitantly with SCFA production. In the Ino-Cp group, but not in the Ino-Bb group, mHMGCoA synthase and glutaminase were expressed at the level observed in the CV rats. These data suggest that the intestinal flora, through butyrate production, could control the expression of colonic mHMGCoA synthase and glutaminase. These modifications in gene expression by butyrate in vivo seem unrelated to a modification of histone acetylation.

Of the oil-soluble organosulfur compounds derived from garlic, diallyl disulfide (DADS) is one of the most abundant. We examined the effect of DADS on gene expression in rat liver. By suppressive subtractive hybridization, we identified the heavy (H)-ferritin gene as a DADS-stimulated gene in the rat liver epithelial (REL) cells. DADS stimulation of H- and L (light)-ferritin mRNA was analyzed in REL cells and in rat liver. Incubation of the REL cells in 10 micro mol/L DADS for 4 h increased H-ferritin 1.9 +/- 0.2-fold, n = 3) and light(L)-ferritin mRNA 1.5 +/- 0.2-fold, n = 3). Stimulation did not occur in the presence of an inhibitor of transcription, actinomycin D. Stimulation of ferritin at the RNA and protein levels was also found in rats administered a DADS-enriched oil solution intragastrically. There was a 3 +/- 1.1-fold increase in H- and 3 +/- 0.14-fold increase for L-ferritin mRNA 24 h after the end of the infusion in the presence of DADS, (n = 3). The expression of the transferrin receptor, an iron transporter, was also enhanced by DADS in rat liver. In conclusion, our data suggest that DADS could modify iron homeostasis through the modulation of ferritin and transferrin receptor gene expression.

Few pharmaceutical studies, with the exception of those on rectal solutions, are described on short chain fatty acid (SCFA) formulations-especially for sodium butyrate, which is a colonocyte preferential substrate. Highly dosed butyrate pellets (90%) were prepared and their coating was designed for colonic delivery. In vivo determination (pH and transit time of pellets in rats) allowed to respectively choose the grade and thickness (resistance of 6 h) of the pH-dependent coating (Eudragi L+S, 1:1). The coated pellets were administered to naturally butyrate-deprived rats. The rats' colonic mucosa had the particularity to weakly express mitochondrial HMG-CoA synthase, an enzyme that responds to luminal butyrate. The results did not show early absorption of butyrate, but a probable cecal loss in the rat cecum as cecal residence time of the pellets was important and as pH was propitious for the coating hydrolysis. It seemed that butyrate, given daily for 7 days without the other main SCFA. was unable to induce the enzyme and/or that the dose (0.32 mmol/day) was insufficient.

We have investigated the possible effects of algal polysaccharides on postprandial blood glucose and insulin responses in an animal model, the pig. Three seaweed fibres of different viscosities, extracted from Palmaria palmata (PP), Eucheuma cottonii (EC), or Laminaria digitata (LD), were compared to purified cellulose (CEL). Blood glucose and plasma insulin levels were monitored and intestinal absorption quantified for 8 h following a high carbohydrate test-meal supplemented with 5% fibre. Digestive contents were also sampled, 5 h postprandial. As compared to CEL, PP had no effect on glucose and insulin responses. The latter decreased with EC, but glucose absorption balance was not modified. LD addition resulted in a dramatically reduced glucose absorption balance, accompanied by a higher amount of starch left in the small intestine. Among polysaccharides tested, only the highly viscous alginates could affect intestinal absorption of glucose and insulin response.

Seaweed extracts, because of their physicochemical characteristics and potential nutritional value, could provide a new source of dietary fibre. This study investigated changes in seaweed fibres (physicochemical and fermentative properties) in different digestive sites and their effects on digesta (viscosity and hydration properties). Sixteen pigs were adapted to a test diet supplemented with 5% algal fibre (either Palmaria palmata (PP), a poorly viscous soluble xylan; or Eucheuma cottonii (EC), a partly insoluble carrageenan; or Laminaria digitata (LD), a highly viscous soluble alginate) or 5% cellulose (reference fibre). PP did not modify the characteristics of digesta and was fermented in the caecum (pH 6.1+/-0.4; short-chain fatty acids measured in digesta, 1409 +/- 691 mu mol g(-1) dry matter). EC and LD were mainly insoluble in the stomach, becoming soluble in the intestine; EC was slightly fermented in the colon, giving a low concentration of short-chain fatty acids (303 +/- 122 mu mol g(-1) dry matter). Supplementation of the diet with alginate (LD) increased 3.5-fold the heal viscosity of digesta and their hydration capacity in the ileum and colon. Thus the physicochemical properties of pig digesta largely depend on the physicochemical properties of the ingested seaweed fibre, the pH and ionic conditions prevailing in the gut, and their fermentability. (C) 2000 Society of Chemical Industry.

Plasma glutamine turnover was determined using 1-14C-labeled glutamine in rats that consumed crystalline amino acid diets containing the equivalent of 16% protein with 25% of the amino acids as glutamine or a control diet containing no glutamine (or glutamate) for 10 days. Glutamine turnover in glutamine-fed animals was 66% of the rate in the control group. Glutamine feeding caused 20% higher levels of arterial plasma glutamine. Arterial-portal differences across the portal-drained viscera showed net glutamine uptake in control animals but no net uptake or release in the glutamine-fed group. Skeletal muscle glutamine synthetase activity was similar in both groups. The results indicate that long-term consumption of relatively large amounts of dietary glutamine decreases the turnover of plasma glutamine and thus reduces the need for endogenous glutamine synthesis.

Nitric oxide synthase (NOS) activities are responsible for the enzymatic conversion of L-arginine into NO and L-citrulline. Relatively low amounts of NO are produced in intestinal epithelial cells or are released from nerve endings. The effects of NO production are related to the maintenance of epithelial integrity and permeability. A pathological role of an increased NO production has been suggested to play a role in models of experimental colitis. In humans, NOS activity in colon mucosa from patients with ulcerative colitis is clearly increased when compared with the activity of the control group. In contrast, an increase of NOS activity in the colon mucosa from patients with Crohn's disease remains controversial. In the present work, we have measured NOS activity in colon biopsies originating from the control group (n = 16), from patients with ulcerative colitis (n = 23) and Crohn's disease (n = 17) using the radiochemical method of the conversion of L-[guanido-14C] arginine into radioactive L-citrulline. In the control group, NOS activity was mainly of the inducible type (88% of total NOS activity) since it was characterised by its insensibility to the absence of calcium in the assay medium. In colon biopsies originating from patients with ulcerative colitis, inducible NOS activity was increased 3 fold (p < 0.005) and in patients with Crohn's disease, inducible NOS activity was increased 5 fold (p < 0.005). Correlations between NOS activity in colon biopsies and the intensity parameters of the disease i.e. Truelove index, endoscopic score and histo-logical parameters were evidenced in patients with ulcerative colitis. In contrast, in patients with Crohn's disease, the high inducible NOS activity was not correlated with any intensity parameters of the disease. From these data, we concluded that although inducible NOS activity was increased several fold in colon biopsies originating from patients with both ulcerative colitis and Crohn's disease, a correlation between this activity and the severity of bowel inflammation was not found in either cases.

sit time in left colon and faecal levels of propionibacteria and bifidobacteria dur- ing ingestion period.

HT-29 cells, originating from a human colon carcinoma, can proliferate in standard culture conditions with an absolute requirement for polyamines. The major precursor provided in the culture medium for polyamine biosynthesis is L-arginine. L-Arginine conversion to L-ornithine by arginase is followed by stepwise conversion of this latter amino acid to putrescine, spermidine and spermine. The aim of the present work was to document the consequences of a total inhibition of L-arginine flux through arginase, resulting in a decreased L-ornithine availability, on HT-29 cell proliferation and polyamine metabolism. L-Valine, a known arginase inhibitor, when used at a high concentration, i.e., 100 mM, inhibits L-arginine flux through arginase almost totally. The addition in the culture medium of 100 mM L-valine or 50 mM NaCl used to mimic the L-valine induced increase in medium osmolality both reduced equally cellular growth. Cell viability, protein synthesis or oxidative metabolism measured in isolated cells were unaffected by the L-valine treatment, suggesting that decreased proliferation was not associated with an acute toxic effect of this aminoacid, but was rather due to the increase in the medium osmolality. L-Valine treated cells displayed an altered polyamine metabolism when compared with control cells grown in the absence of the amino acid. After 4 days of treatment with 100 mM L-valine, L-ornithine flux through ornithine decarboxylase was significantly higher as well as putrescine and spermidine cellular uptakes in treated cells. However, the changes in polyamine metabolism led to similar polyamine cell contents in untreated and L-valine treated cells. In conclusion, we propose that the observed alterations of polyamine metabolism may reflect an adaptative response of HT-29 cells to the presence of L-valine which contribute together with the low amount of L-ornithine present in the culture medium to polyamine homeostasis.

adults (117.2 ± 6.12 versus 144.0 ± 20 min, P < 0.01).2) The levels of anti-oxLDL autoanti- bodies, detected with an ELISA method.Anti-oxLDL IgG titers were higher in chil- dren (1.67 ± 0.41 versus 1.28 ± 0.41 ratio, P < 0.01 ).

Background & Aims: After small bowel resection, parenteral nutrition is often required to provide energy and nitrogen supplies and also to stimulate intestinal adaptation, despite the absence of glutamine in formulas, The aim of this study was to investigate the effect of nutrient supply route on fuel utilization by enterocytes. Methods: Rats received an intravenous or intragastric continuous infusion of an all-in-one glutamine free formula, Sham-operated control rats were orally fed and received the same protein-caloric supplies as the other two groups. On day 7, the rats were killed in the fed state, blood samples were collected, and the jejunoileum was removed, Enterocytes were isolated, Aliquots of cell suspensions were incubated (30 minutes at 37 degrees C) in the presence of [C-14]glucose and [C-14]glutamine (2 mmol/L). Substrate utilization was determined by measuring metabolites and CO2 generated, Results: Intravenously fed rats showed mild hyperglycemia and marked hyperinsulinemia, Plasma glutamine levels were similar in the three groups. Intravenously fed rats showed a simultaneous increase in glutamine utilization and a decrease in glucose utilization compared with intragastrically fed and control rats, without parallel changes in glutaminase and hexokinase activities, The basolateral glucose transporter protein concentration was reduced in intravenously fed rat enterocytes. Conclusions: The route of nutrient delivery influences fuel utilization by enterocytes.

We have reported previously that a high glycolytic capacity develops soon after birth in enterocytes isolated from suckling newborn pigs. In the present work, we investigated whether such metabolic changes could affect intestinal glucose utilization in vivo and examined possible variations in glucose metabolism along the small intestine. Glucose utilization by individual tissues was assessed using the 2-deoxyglucose technique. The overall glucose utilization rate was doubled in suckling vs. fasting 2-day-old pigs because of significantly higher rates in all tissues studied, except for the brain. In parallel, enterocytes were isolated from the proximal, medium, or distal jejunoileum of newborn vs. 2-day-old pigs and assessed for their capacity to utilize, transport, and phosphorylate glucose. Intestinal glucose consumption accounted for approximately 15% of glucose turnover rate in suckling vs. 8% in fasting pigs. Moreover, there was a proximal-to-distal gradient of glucose utilization in the intestinal mucosa of suckling pigs. Such a gradient was also evidenced on isolated enterocytes. The stimulation of both hexokinase activity (HK2 isoform) and basolateral glucose transporter (GLUT2), as observed in the proximal jejunum, could account for such a site-specific effect of suckling.

hepatic TG stored, or from the reesterification of fatty acids com- ing from the hepatic captation of degraded lipoproteins.

Seaweed fibre added to the diet can affect postprandial glycemic response. The aim of this work was to relate the changes in glucose absorption to the chemical and physico-chemical characteristics of digesta from the upper gut. Twelve pigs were fed 4 test meals, supplemented with 5% of cellulose or one of seaweed fibre with various physico-chemical properties: EC (carrageenan, partly soluble fibre), PP (xylane, low viscous fibre), LD (alginate, high viscous fibre). With LD diet the cumulated amount of glucose absorbed was reduced to 56 +/- 9% of the value obtained with cellulose. Starch contents in gastric digesta were similar for all diets. In contrast the increasing of the viscosity measured in the intestinal digesta after LD feeding could have reduced the mixing of luminal contents and thus limited starch digestion and glucose absorption.

Backgyound: L‐Arginine and L‐glutamine are highly metabolized by intestinal cells, leading to various metabolites, including L‐citrulline, which is required for optimal growth. Elemental diets, used in clinical practice to treat growth failure and malnutrition, are very different from complex diets normally consumed. The aim of the present study was to assess the effects of an elemental diet compared with a complex diet on L‐arginine metabolism in rat isolated enterocytes and its modulation by L‐glutamine. Methods: Rats were fed the elemental diet (group ED) or the control diet (group C) for 14 days. Villus enterocytes then were isolated, and metabolic capacities or enzyme activities were assessed. Results: The incubation of enterocytes isolated from group C with 0.1 mmol/LL‐[U‐ 14 C]‐arginine led to the production of 125 ± 25 pmol L‐citrulline/10 6 cells per 30 minutes. This production showed a twofold increase in the presence of 2 mmol/L L‐glutamine. In group ED, L‐citrulline synthesis from L‐arginine was markedly lower in the absence or in the presence of L‐glutamine. This coincided with lower carbamoylphosphate synthase I activity and carbamoylphosphate (CP) content of enterocytes. Other L‐arginine andLglutamine metabolic pathways were not affected. Similar results were obtained when the elemental diet was administered continuously through a gastric catheter or fed by mouth. Conclusions: L‐Glutamine favors the synthesis of L‐citrulline from L‐arginine in isolated enterocytes, probably via an increase in CP production. Changing the diet composition, from a complex to an elemental diet, results in an alteration of the enterocyte capacity to synthesize L‐citrulline from L‐arginine, irrespective of the rhythm of delivery. ( Journal of Parenteral and Enteral Nutrition 21:316–323, 1997)