Glutamine attenuates leukocyte-endothelial cell adhesion in indomethacin-induced intestinal inflammation in the rat

Plasma-Free Amino Acid Profiles in Crohn's Disease: Relationship With the Crohn Disease Activity Index

We aimed to clarify the relationship between plasma-free amino acid (PFAA) profiles and the Crohn's disease (CD) activity index (CDAI) in patients with CD.

METHODS

We measured fasting PFAA concentrations in 29 patients with CD and their correlation with disease activity.

RESULTS

In all patients, significant correlations were noted between CDAI and concentrations of valine, methionine, leucine, histidine, tryptophan, alanine, tyrosine, total amino acids (TAAs), nonessential amino acids (NEAAs), essential amino acids (EAAs), and branched-chain amino acids (BCAAs). In patients with the ileo-colonic type of CD, significant correlations were noted between CDAI and valine, histidine, tryptophan, glutamine, TAA, NEAA, EAA, and BCAA. In ileal type, significant correlations were observed between CDAI and threonine, valine, histidine, serine, and glycine. In colonic type, significant correlations were noted between CDAI and valine, histidine, tryptophan, TAA, NEAA, EAA, and BCAA.

CONCLUSIONS

In patients with CD, plasma amino acids appear to be associated with disease activity.

Effects of Glutamine and Omega-3 Fatty Acids on Erythrocyte Deformability and Oxidative Damage in Rat Model of Enterocolitis

Background

The aim of the study was to investigate preventive effects of glutamine (Gln), omega-3 fatty acids (FA) on erythrocyte deformability (EDEF) in rat model of indomethacin-induced enterocolitis.

Methods

Nineteen Wistar albino male rats were divided into three groups: control group, colitis induced by indomethacin and were fed with a standard laboratory diet (group 1), and colitis induced by indomethacin and were also fed with Gln, omega-3 FA (group 2). An investigation was performed in a rat model of experimental colitis induced by subcutaneous injections of 2 mL intdomethacine solution applied at 24 and 48 hours intervals to male Wistar rats for 14 days. Gln and omega-3 FA were added to the daily standard diets of the animals during 14 days of injections. During the study, changes in body weight were evaluated. The intestines were examined, and colitis was macroscopic and histologically scored. The circulating tumor necrosis factor alpha (TNF-α) and interleukine-1β (IL-1β), erythrocyte transit time (ETT) and thiobarbituric acid reactive substances (TBARS) levels were determined in addition to calculation of EDEF indices in all groups.

Results

No significant differences in body weight changes could be determined between the standard diet and special diet groups at the end of the experiment. After macroscopic and microscopic scoring, in all of the groups that colitis was found induced, the lowest microscopic score was observed in the group 2. But Gln and omega-3 FA supplemented diet did not change the mean macroscopic and histological scores in all rats. The proliferating cell nuclear antigen (PCNA) levels were significantly higher in group 1 and group 2 compared to the control group. Effects of the diet on circulating TNF-α and IL-1β levels were found correlated with inflammation but statistically significant differences were not found in the group 1 and group 2 (P < 0.05). The ETT and TBARS levels in standard and special diet groups were significantly increased (P < 0.05). However, EDEF indices which are an important parameter of the study were decreased in indomethacin-induced enterocolitis groups that fed with standard and special diet.

Conclusions

Increases in ETT and TBARS levels did not return to normal by addition of Gln and omega-3 FA to diet. Our results suggest that determination of effective optimal doses and route of administration for these nutrients may play an important role in reducing EDEF and microvascular changes.

Impact of nutrition on brain development and its neuroprotective implications following preterm birth

The impact of nutrition on brain development in preterm infants has been increasingly appreciated. Early postnatal growth and nutrient intake have been demonstrated to influence brain growth and maturation with subsequent effects on neurodevelopment that persist into childhood and adolescence. Nutrition could also potentially protect against injury. Inflammation and perinatal infection play a crucial role in the pathogenesis of white matter injury, the most common pattern of brain injury in preterm infants. Therefore, nutritional components with immunomodulatory and/or anti-inflammatory effects may serve as neuroprotective agents. Moreover, growing evidence supports the existence of a microbiome-gut-brain axis. The microbiome is thought to interact with the brain through immunological, endocrine, and neural pathways. Consequently, nutritional components that may influence gut microbiota may also exert beneficial effects on the developing brain. Based on these properties, probiotics, prebiotic oligosaccharides, and certain amino acids are potential candidates for neuroprotection. In addition, the amino acid glutamine has been associated with a decrease in infectious morbidity in preterm infants. In conclusion, early postnatal nutrition is of major importance for brain growth and maturation. Additionally, certain nutritional components might play a neuroprotective role against white matter injury, through modulation of inflammation and infection, and may influence the microbiome-gut-brain axis.

Glutamine supplementation attenuates expressions of adhesion molecules and chemokine receptors on T cells in a murine model of acute colitis

Background. Migration of T cells into the colon plays a major role in the pathogenesis in inflammatory bowel disease. This study investigated the effects of glutamine (Gln) supplementation on chemokine receptors and adhesion molecules expressed by T cells in mice with dextran sulfate sodium- (DSS-) induced colitis. Methods. C57BL/6 mice were fed either a standard diet or a Gln diet replacing 25% of the total nitrogen. After being fed the diets for 5 days, half of the mice from both groups were given 1.5% DSS in drinking water to induce colitis. Mice were killed after 5 days of DSS exposure. Results. DSS colitis resulted in higher expression levels of P-selectin glycoprotein ligand- (PSGL-) 1, leukocyte function-associated antigen- (LFA-) 1, and C-C chemokine receptor type 9 (CCR9) by T helper (Th) and cytotoxic T (Tc) cells, and mRNA levels of endothelial adhesion molecules in colons were upregulated. Gln supplementation decreased expressions of PSGL-1, LFA-1, and CCR9 by Th cells. Colonic gene expressions of endothelial adhesion molecules were also lower in Gln-colitis mice. Histological finding showed that colon infiltrating Th cells were less in the DSS group with Gln administration. Conclusions. Gln supplementation may ameliorate the inflammation of colitis possibly via suppression of T cell migration.

New therapeutic strategy for amino acid medicine: prophylactic and healing promoting effect of monosodium glutamate against NSAID-induced enteropathy

We reviewed the effect of monosodium glutamate (MSG) on the development and healing of nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal lesions in rats. Loxoprofen (60 mg/kg, p.o.) induced lesions in the small intestine within 24 h, accompanied by a decrease of Muc2 expression and an increase in enterobacterial invasion and inducible nitric oxide synthase (iNOS) expression. These lesions were prevented when MSG was given as a mixture of powdered food for 5 days before the loxoprofen treatment. This effect of MSG was accompanied by an increase in Muc2 expression / mucus secretion as well as the suppression of bacterial invasion and iNOS expression. These intestinal lesions healed spontaneously within 6 days, but the process was impaired by the repeated administration of low-dose loxoprofen (30 mg/kg) for 5 days after the ulceration, with the decrease of vascular endothelial derived growth factor (VEGF) expression and angiogenesis. The healing-impairing effect of loxoprofen was prevented by feeding 5% MSG for 5 days after the ulceration. These results suggest that MSG not only prevents loxoprofen-induced small intestinal damage but also promotes a healing of these lesions; the former is functionally associated with the increase in Muc2 expression / mucus secretion and the suppression of bacterial invasion and iNOS expression, while the latter is associated with the stimulation of VEGF expression/angiogenesis.

Intravenous free and dipeptide-bound glutamine maintains intestinal microcirculation in experimental endotoxemia

OBJECTIVE

The administration of glutamine (Gln), which is depleted in critical illness, is associated with an improvement of gut metabolism, structure, and function. The aim of the present study was to evaluate the effects of intravenous Gln and its galenic formulation, l-alanyl-l-glutamine dipeptide (AlaGln), on the intestinal microcirculation during experimental endotoxemia using intravital fluorescence microscopy. Gln or AlaGln administration was performed as pretreatment or post-treatment, respectively. To identify further the underlying mechanisms, amino acid levels were studied.

METHODS

Sixty male Lewis rats were randomly divided into six groups (n = 10/group): control, LPS (lipopolysaccharide 5 mg/kg intravenously), Gln/LPS (LPS animals pretreated with Gln 0.75 g/kg Gln intravenously), AlaGln/LPS (LPS animals pretreated with AlaGln intravenously, 0.75 g/kg Gln content), LPS/Gln (LPS animals post-treated with Gln 0.75 g/kg intravenously), and LPS/AlaGln (LPS animals post-treated with AlaGln intravenously, 0.75 g/kg Gln content). Two hours after the endotoxin challenge, the microcirculation of the terminal ileum was studied using intravital fluorescence microscopy. Blood samples were drawn at the beginning, during, and the end of the experiment to determine the amino acid levels.

RESULTS

The Gln and AlaGln pre- and post-treatment, respectively, prevented the LPS-induced decrease in the functional capillary density of the intestinal muscular and mucosal layers (P < 0.05). The number of adherent leukocytes in the submucosal venules was significantly attenuated after the Gln and AlaGln pre- and post-treatment (P < 0.05).

CONCLUSION

The Gln and AlaGln administrations improved the intestinal microcirculation by increasing the functional capillary density of the intestinal wall and decreasing the submucosal leukocyte activation.

GC/MS-based profiling of amino acids and TCA cycle-related molecules in ulcerative colitis

OBJECTIVE

The roles that amino acids play in immunity and inflammation are well defined, and the relationship between inflammatory bowel disease (IBD) and certain amino acids has recently attracted attention. In this study, the levels of amino acids and trichloroacetic acid (TCA) cycle-related molecules in the colonic tissues and sera of patients with ulcerative colitis (UC) were profiled by gas chromatography/mass spectrometry (GC/MS), with the aim of evaluating whether the clinical state induced by UC leads to variations in the amino acid profile.

MATERIALS AND METHODS

Colonic biopsy samples from 22 UC patients were used, as well as serum samples from UC patients (n = 13), Crohn's disease (CD) patients (n = 21), and healthy volunteers (n = 17).

RESULTS

In the GC/MS-based profiling of amino acids and TCA cycle-related molecules, lower levels of 16 amino acids and 5 TCA cycle-related molecules were observed in the colonic lesion tissues of the UC patients, and the serum profiles of amino acids and TCA cycle-related molecules of the UC patients were different from those of the CD patients and healthy volunteers.

CONCLUSIONS

Our study raises the possibility that GC/MS-based profiling of amino acids and TCA cycle-related molecules is a useful early diagnostic tool for UC.

GC/MS-based profiling of amino acids and TCA cycle-related molecules in ulcerative colitis

OBJECTIVE

The roles that amino acids play in immunity and inflammation are well defined, and the relationship between inflammatory bowel disease (IBD) and certain amino acids has recently attracted attention. In this study, the levels of amino acids and trichloroacetic acid (TCA) cycle-related molecules in the colonic tissues and sera of patients with ulcerative colitis (UC) were profiled by gas chromatography/mass spectrometry (GC/MS), with the aim of evaluating whether the clinical state induced by UC leads to variations in the amino acid profile.

MATERIALS AND METHODS

Colonic biopsy samples from 22 UC patients were used, as well as serum samples from UC patients (n = 13), Crohn's disease (CD) patients (n = 21), and healthy volunteers (n = 17).

RESULTS

In the GC/MS-based profiling of amino acids and TCA cycle-related molecules, lower levels of 16 amino acids and 5 TCA cycle-related molecules were observed in the colonic lesion tissues of the UC patients, and the serum profiles of amino acids and TCA cycle-related molecules of the UC patients were different from those of the CD patients and healthy volunteers.

CONCLUSIONS

Our study raises the possibility that GC/MS-based profiling of amino acids and TCA cycle-related molecules is a useful early diagnostic tool for UC.

Potential for amino acids supplementation during inflammatory bowel diseases

The pathophysiology of inflammatory bowel diseases (IBDs) is multifactorial and involves interactions of gut luminal content with mucosal barrier and especially immune cells. Malnutrition is a frequent issue during IBD flares, especially in Crohn's disease (CD) patients, and nutritional support is frequently used to treat malnutrition but also in an attempt to modulate intestinal inflammation. The use of oral or enteral nutrition intervention in IBDs may be effective, alone or in combination with drugs, to achieve and maintain remission. However, standard diets are less effective than new-generation biotherapies and could be improved by supplementation with specific immunomodulatory amino acids. Experimental studies evaluating glutamine, the preferential substrate for enterocytes, are promising. Some clinical studies with oral glutamine in CD are until now disappointing, but new formulations and targeting could enhance glutamine efficacy at the site of mucosal lesions. The role of arginine, involved in nitric oxide and polyamines synthesis, still remains debated. However, the effects of these amino acids in IBD have been poorly documented in humans. Other candidates like glycine, cysteine, histidine, or taurine should also be evaluated in the future.

Influence of glutamine on intestinal inflammatory response, mucosa structure alterations and apoptosis following traumatic brain injury in rats

Traumatic brain injury (TBI) can induce a persistent inflammatory response, histopathological changes and apoptosis in the intestine. Glutamine has been shown to reduce bacterial translocation and maintain intestine mucosal integrity, but its effects on the inflammatory response, structural alterations and apoptosis in intestinal mucosa following TBI have not been previously investigated. Using the weight-drop method, a right parietal cortical contusion was induced in rats and, for the next 5 days, they were fed either chow alone or chow mixed with glutamine. Intestinal tissue samples were then removed for analysis. Following TBI, glutamine supplementation was found to: decrease intestinal concentrations of interleukin (IL) -1beta, tumour necrosis factor-alpha (TNF-alpha) and IL-6; downregulate intercellular adhesion molecule-1 (ICAM-1) expression; attenuate TBI-induced damage to the intestine structure; and reduce apoptosis. These results suggest that post-TBI glutamine administration could suppress intestinal inflammation, protect intestinal mucosal structure and reduce mucosal apoptosis.

Low intestinal glutamine level and low glutaminase activity in Crohn's disease: a rational for glutamine supplementation?

Intestinal glutamine utilization is integral to mucosal regeneration. We analyzed the systemic and intestinal glutamine status in Crohn's disease (CD) and evaluated the therapeutic effect of glutamine supplementation in an animal model of ileitis. In CD, glutamine concentrations were decreased systemically and in noninflamed and inflamed ileal/colonic mucosa. Mucosal glutaminase activities were depressed in the ileum independent of inflammation but were not different from controls in the colon. In experimental ileitis, oral glutamine feeding prevented macroscopic inflammation, enhanced ileal and colonic glutaminase activities above controls, and normalized the intestinal glutathione redox status. However, glutamine supplementation enhanced myeloperoxidase activity along the gastrointestinal tract and potentiated lipid peroxidation in the colon. In conclusion, glutamine metabolism is impaired in CD. In experimental ileitis, glutamine supplementation prevents inflammatory tissue damage. In the colon, however, which does not use glutamine as its principal energy source, immune enhancement of inflammatory cells by glutamine increases oxidative tissue injury.

Dietary glutamine supplementation reduces cellular adhesion molecule expression and tissue myeloperoxidase activity in mice with gut-derived sepsis

OBJECTIVES

This study investigated the effects of glutamine (Gln) on plasma intracellular adhesion molecule-1 levels and leukocyte integrin (CD11a/CD18 and CD11b/CD18) expressions in gut-derived sepsis. Myeloperoxidase (MPO) activities in organs were also analyzed to identify the extent of tissue injury resulting from neutrophil infiltration.

METHODS

Mice were randomly assigned to a normal group (NC), a control group, or a Gln group. The NC group was fed standard chow diet; the control group was fed a common semipurified diet; and the Gln group received a diet in which part of the casein was replaced by Gln, which provided 25% of total amino acid nitrogen. After 3 wk, sepsis was induced by cecal ligation and puncture (CLP) in the control and Gln groups. Mice in the experimental groups were killed at 0, 6, 12, and 24 h after CLP. Mice in the NC group were killed when CLP was performed. Blood and organ samples were collected for further analysis.

RESULTS

Plasma intracellular adhesion molecule-1 levels were significantly lower in the Gln group than in the control group at 6, 12, and 24 h after CLP. Expressions of lymphocyte CD11a/CD18 were significantly higher, whereas polymorphonuclear lymphocyte expressions of CD11b/CD18 were lower in the Gln group than in the corresponding control group at 6 and 12 h after CLP. In comparisons of MPO activities in various organs, the Gln group had lower MPO activities at 6 and 12 h in the lung, at 6, 12, and 24 h in the liver, at 12 and 24 h in the kidneys, and at 12 h in the intestine than those in the control group.

CONCLUSIONS

Results of this study demonstrate that a Gln-supplemented enteral diet increased lymphocyte CD11a/CD18 expressions, whereas neutrophil CD11b/CD18 expressions, circulating intracellular adhesion molecule-1 levels, and MPO activities in various organs decreased with gut-derived sepsis. These findings suggest that, under septic conditions, Gln administration may enhance lymphocyte function, attenuate interactions between polymorphonuclear lymphocytes and endothelium, and thus may decrease neutrophil infiltration into tissues.

EFFECT OF GLUTAMINE ON CELLULAR ADHESION MOLECULE EXPRESSION AND LEUKOCYTE TRANSMIGRATION IN ENDOTHELIAL CELLS STIMULATED BY PLASMA OR PERITONEAL DRAIN FLUID FROM A SURGICAL PATIENT

This study investigated the effect of glutamine (GLN) concentration on surface molecule expression on endothelial cells (ECs) and leukocytes and the transendothelial migration of polymorphonuclear neutrophils (PMNs) through ECs stimulated by plasma or peritoneal drain fluid (PDF) from a surgical patient. Human umbilical vein ECs (HUVECs) and PMNs from normal subjects were treated with different concentrations (0, 300, 600, and 1000 micromol/L) of GLN for 24 h. After that, HUVECs were stimulated for 3 h with plasma or PDF from a patient who had undergone abdominal surgery, and PMNs were allowed to transmigrate through ECs for 2 h. HUVEC surface expression of cell adhesion molecules and integrin (CD11b) and interleukin (IL) 8 receptor expression on PMNs were measured by flow cytometry. PMNs transmigrating through ECs were also analyzed. The results showed that cell adhesion molecule and integrin expressions in PDF groups were higher than those in control groups. Among the PDF groups, cellular adhesion molecule expressions on ECs and CD11b expression on PMNs were lower with 600 and 1000 micromol/L than with 300 micromol/L GLN. IL-8 secretions from ECs and PMNs were higher with 300 and 600 micromol/L than with 1000 micromol/L GLN, and this was consistent with the expression of the IL-8 receptor on PMNs. PMN transmigration was significantly higher with 300 micromol/L GLN than with the other GLN concentrations. HUVECs stimulated by plasma from surgical patient had the similar effects on surface molecule expression as PDF; however, the influences were not so obvious as shown in PDF stimulation. The results of this in vitro study suggest that ECs and PMNs were activated after patient's plasma or PDF stimulation. A low GLN concentration comparable to catabolic conditions resulted in higher adhesion molecule expression and greater transendothelial migration of neutrophils. GLN administration at levels similar to or higher than physiological concentrations reduced IL-8 and adhesion molecule expression, and PMN transmigration was also decreased after stimulation with plasma or PDF from a surgical patient.

Effects of glutamine on adhesion molecule expression and leukocyte transmigration in endothelial cells exposed to arsenic

This study evaluated whether glutamine (GLN) concentration was related to endothelial surface molecule expression and the migration of polymorphonuclear neutrophils (PMNs) through endothelial cells (ECs) stimulated by arsenic. Human umbilical vein endothelial cells (HUVECs) and PMNs were treated with different GLN concentrations (0, 300, 600 and 1000 microM) for 24 h. After that, we stimulated HUVECs for 3 h with 0.5 microM arsenic, and PMNs were allowed to transmigrate to ECs for 2 h. HUVEC surface expressions of cell adhesion molecules and integrin (CD11b) and interleukin (IL)-8 receptor expressions on PMNs were measured. The transendothelial migration of PMNs was also analyzed. The results showed that cell adhesion molecule (CAM) and integrin expressions in arsenic groups were higher than in those without arsenic. Among the arsenic groups, the expression of CAMs on ECs and CD11b, and IL-8 receptor on PMNs was lowest with 0 microM compared with the other GLN concentrations. Vascular CAM-1 on ECs and CD11b on PMN expression were higher with 300 microM than with 600 and 1000 microM GLN. IL-8 secretions from ECs and PMNs were higher with 300 muM than with 600 and 1000 microM GLN, and this was consistent with the expression of the IL-8 receptor on PMNs. Polymorphonuclear neutrophil transmigration was significantly higher with 300 muM GLN than with other GLN concentrations. These results suggest that ECs and PMNs were activated after arsenic stimulation. Cell adhesion molecule expressions on ECs and PMNs were suppressed in the absence of GLN. A low GLN concentration comparable to catabolic conditions resulted in higher adhesion molecule expression and greater transendothelial migration of neutrophils. Glutamine administration at levels similar to or higher than physiological concentrations reduced IL-8 and adhesion molecule expression; PMN transmigration was also decreased after stimulation with arsenic.

Effect of glutamine on cell adhesion molecule expression and leukocyte transmigration in endothelial cells stimulated by preeclamptic plasma

OBJECTIVE

This study analyzed plasma glutamine (GLN) concentrations in women with preeclampsia. Also, in an in vitro study we evaluated whether GLN concentration was related to surface molecule expressions on endothelial cells (ECs) and polymorphonuclear neutrophils (PMNs) and the transendothelial migration of PMNs through ECs stimulated by preeclamptic plasma.

METHODS

Blood samples were collected from 20 women with preeclampsia and 15 normal pregnant women for plasma GLN analysis. In the in vitro study, human umbilical vein endothelial cells and PMNs were treated with different concentrations (0, 300, 500, and 1000 microM) of GLN for 24 h. After that, we stimulated human umbilical vein endothelial cells for 3 h with plasma from patients with preeclampsia, and PMNs were allowed to transmigrate through ECs for 2 h. EC surface expressions of cellular adhesion molecules (CAMs) and integrin (CD11b) interleukin-8 (IL-8) receptor expressions on PMNs were measured by flow cytometry. The transendothelial migration of PMNs through ECs was also analyzed.

RESULTS

Women with preeclampsia exhibited significantly lower plasma GLN concentrations than did normal pregnant women. The in vitro study showed that, compared with normal plasma, CAM expressions on human umbilical vein endothelial cells and PMNs were increased when preeclamptic plasma was stimulated. Among the groups with preeclamptic plasma stimulation, intracellular CAM-1 expression on ECs and CD11b and IL-8 receptor expressions on PMNs were lower with 500 and 1000 microM than with 300 microM of GLN. IL-8 production from ECs and PMNs was also lower with 500 and 1000 microM than with 300 microM of GLN. PMN transmigration was significantly higher with 300 microM of GLN than with the other GLN concentrations.

CONCLUSIONS

Plasma GLN is depleted in women with preeclampsia. The result of this in vitro study showed that ECs and PMNs were activated after preeclamptic plasma stimulation. A low GLN concentration resulted in greater CAM expression and greater transendothelial migration of neutrophils. GLN administration at levels similar to or higher than physiologic concentrations decreased IL-8 and CAM expressions, and PMN transmigration decreased after stimulation with preeclamptic plasma.

Oral glutamine attenuates indomethacin-induced small intestinal damage

The use of NSAIDs (non-steroidal anti-inflammatory drugs), although of great therapeutic value clinically, is limited by their tendency to cause mucosal damage in the gastrointestinal tract. In the small intestine, the effects these drugs have been shown to produce include inhibition of cyclo-oxygenase, mitochondrial dysfunction and free radical-induced oxidative changes, all of which contribute to the mucosal damage seen. Glutamine is a fuel preferentially used by enterocytes and is known to contribute to maintaining the integrity of these cells. In the present study, we investigated the effect of glutamine on indomethacin-induced changes in the small intestinal mucosa. Rats were given 2% glutamine or glutamic acid or isonitrogenous amino acids, glycine or alanine, in the diet for 7 days. Indomethacin was then administered orally at a dose of 40 mg/kg of body weight. After 1 h, the small intestine was removed and used for the measurement of parameters of oxidative stress and mitochondrial and BBM (brush border membrane) function. Evidence of oxidative stress was found in the mucosa of the small intestine of drug-treated rats, as indicated by significantly increased activity of xanthine oxidase (P < 0.001) and myeloperoxidase (P < 0.001), with corresponding decreases in the levels of several free radical scavenging enzymes and alpha-tocopherol (P < 0.001 in all cases). Levels of products of peroxidation were also significantly elevated (P < 0.001 for all the parameters measured). In addition, oxidative stress was evident in isolated intestinal mitochondria and BBMs (P < 0.001 for all the parameters measured), with associated alterations in function of these organelles (P < 0.001 for all the parameters measured). Supplementation of the diet with glutamine or glutamic acid prior to treatment with indomethacin produced significant amelioration in all the effects produced by the drug in the small intestine (P < 0.001 for all the parameters measured). Glycine and alanine were found to be much less effective in these respects.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.

Glutamine and the gastrointestinal tract

The amino acid glutamine has become one of the most intensively studied nutrients in the field of nutrition and metabolic support. A variety of studies in cell culture systems, animal models of gut mucosal atrophy, injury/repair and adaptation and a limited number of clinical trials demonstrate trophic and cytoprotective effects of glutamine in small bowel and colonic mucosal cells. Although the routine clinical use of glutamine-enriched parenteral and enteral nutrient solutions remains controversial, available data demonstrate both the safety and metabolic and clinical efficacy of glutamine treatment in selected patient groups. Basic investigations are elucidating underlying mechanisms of glutamine action in intestinal cells. These will inform preclinical and clinical investigations designed to determine glutamine efficacy in selected gastrointestinal disorders. Emerging clinical trials will further define the utility of adjunctive glutamine supplementation as a component of specialized nutrition support in gastrointestinal disease.

Nutritional care of pancreatitis and its complications

This article reviews the current literary data on the role of conservative supportive treatment for acute pancreatitis, with special emphasis on parenteral and enteral nutrition. Despite the fact that the indications for both methods have been discussed, defined and widely accepted in recent years, enteral nutrition is currently the focus of recent clinical investigations for use in acute pancreatitis.