Oral glutamine does not prevent bacterial translocation in rats subjected to intestinal obstruction and Escherichia coli challenge but reduces systemic bacteria spread

Effects of nitric oxide synthase inhibition on glutamine action in a bacterial translocation model

Glutamine may be a precursor for NO synthesis, which may play a crucial role in bacterial translocation (BT). The goal of the present study was to investigate the potential effects of glutamine on BT and the immunological response in an experimental model of NO synthase inhibition by NG-nitro-L-arginine methyl ester (l-NAME). Mice were randomly assigned to four groups: sham; intestinal obstruction (IO); IO+500 mg/kg per d glutamine (GLN); IO+GLN plus 10 mg/kg per d l-NAME (GLN/LN). The groups were pretreated for 7 d. BT was induced by ileal ligation and was assessed 18 h later by measuring the radioactivity of 99mTc-Escherichiacoli in the blood and organs. Mucosal damage was determined using a histological analysis. Intestinal permeability (IP) was assessed by measuring the levels of 99mTc-diethylenetriaminepentaacetic acid in the blood at 4, 8 and 18 h after surgery. IgA and cytokine concentrations were determined by ELISA in the intestinal fluid and plasma, respectively. BT was increased in the GLN/LN and IO groups than in the GLN and sham groups. IP and intestinal mucosa structure of the sham, GLN and GLN/LN groups were similar. The GLN group had the highest levels of interferon-γ, while IL-10 and secretory IgA levels were higher than those of the IO group but similar to those of the GLN/LN group. The present results suggest that effects of the glutamine pathway on BT were mediated by NO. The latter also interferes with the pro-inflammatory systemic immunological response. On the other hand, IP integrity preserved by the use of glutamine is independent of NO.

Amino acid and vitamin supplementation improved health conditions in elderly participants

The purpose of this study was to investigate the effects of supplementation with amino acids and vitamins on health conditions in unhealthy older people. One bedridden inpatient group (n = 10; mean age, 79.8 ± 8.5 y) and one outpatient group (n = 9; mean age, 72.9 ± 12.2 y) participated in this study. A mixture supplementation with amino acids containing arginine (500 mg/day), glutamine (600 mg/day), and leucine (1200 mg/day), and 11 kinds of vitamins was daily administrated for 8 weeks. In both groups, general blood biomarkers such as white blood cell count, natural killer cell activity, and C-reactive protein levels were measured. All measurements were taken before (baseline), at 4 weeks (mid-point), and after each trial (post-point). At mid-point, natural killer cell activity in the outpatient group increased significantly compared to baseline. At post-point, natural killer cell activity in the outpatient and inpatient groups increased significantly compared to baseline. The other blood biomarkers did not show any significant change throughout the trial. This pilot study suggested that a mixture of arginine, glutamine, leucine, and vitamins is useful to support innate immunity in unhealthy older people, even if their diseases, symptoms, and prescribed medicines are different.

Glutamine supplementation decreases intestinal permeability and preserves gut mucosa integrity in an experimental mouse model

BACKGROUND

Glutamine (GLN) is the preferred fuel for enterocytes, and GLN supplementation is critical during stressful conditions. The aim of this study was to evaluate the effect of GLN on intestinal barrier permeability and bacterial translocation in a murine experimental model.

METHODS

Swiss male mice (25-30 g) were randomized into 3 groups: (1) sham group; (2) intestinal obstruction (IO) group; (3) IO and GLN (500 mg/kg/d) group. Two different experiments were carried out to assess intestinal permeability and bacterial translocation. In the first experiment, the animals were divided into the 3 groups described above and received diethylenetriamine pentaacetate radiolabeled with technetium ((99m)Tc) on the eighth day. At different time points after intestinal obstruction, blood was collected to determine radioactivity. The animals were killed, and the small intestine was removed for histological analyses. In the bacterial translocation study, on the eighth day all groups received Escherichia coli labeled with (99m)Tc. After 90 minutes, the animals underwent intestinal obstruction and were killed 18 hours later. Blood, mesenteric lymph nodes, liver, spleen, and lungs were removed to determine radioactivity. Statistical significance was considered when P < or = .05.

RESULTS

The levels of intestinal permeability and bacterial translocation were higher in the IO group than in the sham and GLN groups (P < .05). GLN decreased intestinal permeability and bacterial translocation to physiologic levels in the treated animals and preserved intestinal barrier integrity.

CONCLUSIONS

GLN had a positive impact on the intestinal barrier by reducing permeability and bacterial translocation to physiologic levels and preserving mucosal integrity.

Influence of glutamine on morphological and functional changes of liver in the presence of extrahepatic biliary obstruction in rats

PURPOSE: To study the influence of glutamine on functional and morphological changes of liver in the extrahepatic biliary obstruction through an experimental model in rats. METHODS: Seventy Wistar rats were divided into four groups: control (group C) fictitious operation, (group FO), submitted to laparotomy with handling of bile ducts, but without hepatic duct ligation, (group EBO) submitted to laparotomy and hepatic duct ligation, one of them submitted to supplementation with glutamine 2% (group G). The control group consisted of 6 animals. The animals from groups FO, EBO and G were divided into three groups consisting of 6 animals each, being sacrificed at 7, 14 and 21 days after operation, respectively. Blood samples were collected for biochemical analysis and a fragment of liver tissue was collected from the middle lobe for histological analysis. RESULTS: Both for biochemical analysis (BT, aspartate and alanine aminotransferase AST, ALT and alkaline phosphatase FAL) and for histopathological changes (fibrosis, portal inflammation, parenchymal inflammation, hepatocytic changes and duct proliferation), no statistical difference between groups submitted to extrahepatic biliary obstruction (EBO) with and without treatment with glutamine (G) was observed. CONCLUSION: Glutamine supplementation did not alter the prognosis of liver enzymes and histopathological changes in animals submitted to extrahepatic biliary obstruction.

Review article: bacterial translocation in the critically ill--evidence and methods of prevention

BACKGROUND

Delayed sepsis, systemic inflammatory response syndrome (SIRS) and multiorgan failure remain major causes of morbidity and mortality on intensive care units. One factor thought to be important in the aetiology of SIRS is failure of the intestinal barrier resulting in bacterial translocation and subsequent sepsis.

AIM

This review summarizes the current knowledge about bacterial translocation and methods to prevent it.

METHODS

Relevant studies during 1966-2006 were identified from a literature search. Factors, which detrimentally affect intestinal barrier function, are discussed, as are methods that may attenuate bacterial translocation in the critically ill patient.

RESULTS

Methodological problems in confirming bacterial translocation have restricted investigations to patients undergoing laparotomy. There are only limited data available relating to specific interventions that might preserve intestinal barrier function or limit bacterial translocation in the intensive care setting. These can be categorized broadly into pre-epithelial, epithelial and post-epithelial interventions.

CONCLUSIONS

A better understanding of factors that influence translocation could result in the implementation of interventions which contribute to improved patient outcomes. Glutamine supplementation, targeted nutritional intervention, maintaining splanchnic flow, the judicious use of antibiotics and directed selective gut decontamination regimens hold some promise of limiting bacterial translocation. Further research is required.

The impact of arginine on bacterial translocation in an intestinal obstruction model in rats

BACKGROUND & AIMS

Arginine has been shown to have multiple beneficial metabolic and immunologic effects in stress situations. Supplementation of arginine has been shown to promote wound healing and intestinal mucosal recovery after trauma, ischemia or intestinal resection. Bacterial translocation has also been evaluated although with conflicting results and using different assessing techniques. Therefore, the aim of this study was to evaluate the effects of arginine on bacterial translocation in an intestinal obstruction model in rats using Escherichia coli labeled with 99mTechnetium.

METHODS

Male Wistar rats (250-350 g) were randomized to receive conventional chow, diet supplemented with pure arginine or diet supplemented with an immunonutrition enteral formula, enriched with arginine, omega-3 fatty acid and RNA. After 7 days, the animals were anesthetized. Terminal ileum was isolated and a ligature was placed around it. E. coli labeled with 99mTechnetium (99mTc-E. coli) was inoculated into the intestinal lumen (terminal ileum). After 24 h, the animals were sacrificed. Blood, mesenteric lymph nodes (MLN), liver, spleen and lungs were removed for radioactivity determination.

RESULTS

Arginine supplementation (300 mg/day, 600 mg/day or present in the enteral formula) reduced the level of bacterial translocation when compared with the control group (p<0.05). This was shown by significantly decrease uptake of 99mTc-E. coli in blood, MLN, liver, spleen and lungs of the animals in the experimental groups (p < 0.05).

CONCLUSIONS

These results have shown that arginine was able to decrease bacteria translocation despite intestinal obstruction. There are several mechanisms which might explain the role of arginine and these will be the subject of future studies.

Glutamine improves intestinal barrier function in experimental biliary obstruction

OBJECTIVE

To determine the effects of enteral administration of glutamine on intestinal barrier function in experimental biliary obstruction.

BACKGROUND

Extrahepatic biliary obstruction is associated with the failure of intestinal barrier function, allowing bacteria and other substances from the intestine to enter the circulation and initiate a systemic inflammatory response, causing impairment of multiple organs. The amino acid glutamine has been shown to improve intestinal barrier function in other conditions, but its effects in biliary obstruction have not been fully examined.

METHODS

This study examined the effects of enteral administration of glutamine on intestinal permeability and on bacterial translocation from the intestine in a rodent model of biliary obstruction.

RESULTS

Glutamine was shown to reduce intestinal permeability measured as percentage excretion of 14C 7 days after biliary obstruction (0.35+/-0.03 vs. 0.56+/-0.085% in controls, p=0.028), and glutamine administration was also associated with a decreased incidence of bacterial translocation to extra-intestinal sites (p=0.03). Radiolabelled bacterial studies also demonstrated reduced translocation of bacterial fragments to extra-intestinal sites in glutamine-treated animals (p=0.01). There was also some evidence of decreased exposure to endotoxin, reduced systemic inflammation and increased bacterial killing by the immune system in glutamine-treated animals.

CONCLUSIONS

Glutamine modulates intestinal permeability and reduces bacterial translocation in an animal model of experimental biliary obstruction and may increase bacterial killing by the immune system.

Prevention of bacterial translocation using glutamine: a new strategy of investigation

OBJECTIVE

This study investigated the role of glutamine (Gln) on bacterial translocation in an intestinal obstruction model by using Escherichia coli labeled with technetium 99m (99mTc-E. coli).

METHODS

Intestinal obstruction was performed by a single ligature of the terminal ileum in rats. Animals in the control group (group 1) were sham operated (not obstructed). Experimental group 2 had intestinal obstruction. Groups 1 and 2 were not treated with Gln. Groups 3 and 4 were treated with Gln for 7 d before surgery with 250 and 500 mg x kg(-1) x d(-1), respectively. A suspension containing 100 million colony-forming units/mL of (99m)Tc-E. coli was injected into the lumen of the ileum. Twenty-four hours after surgery, blood, mesenteric lymph nodes, livers, spleens, and lungs were collected for determination of radioactivity. The Mann-Whitney U test was performed for statistical analysis. P <or= 0.05 was considered statistically significant.

RESULTS

Rats that had an intestinal obstruction showed a significant increase in 99mTc-E. coli translocation from the lumen to all organs investigated compared with the sham-operated group (P <or= 0.01). There was a significant difference between the intestinally obstructed group and Group 4 treated with Gln at 500 mg x kg(-1) x d(-1) (P <or= 0.05), which did not occur in Group 3 treated with Gln at 250 mg x kg(-1) x d(-1).

CONCLUSIONS

The new method using 99mTc-E. coli was found to be suitable for studies of bacterial translocation. Gln did not prevent bacterial translocation but did significantly decrease the spread of 99mTc-E. coli among organs such as the liver, lung, and spleen. The effect of Gln in cases of intestinal obstruction was found to be dose dependent.

Effect of oral glutamine administration on bacterial tanslocation, endotoxemia, liver and ileal morphology, and apoptosis in rats with obstructive jaundice

Postoperative complications in patients with obstructive jaundice remain increased when associated with endotoxemia and the inflammatory response due to gut barrier failure. Administration of glutamine has been proposed to maintain the integrity of the gut mucosa and thus reduce bacterial translocation (BT), but the effects of this pretreatment on apoptosis and histologic morphology of various organs affected by BT in obstructive jaundice have not been studied. We therefore studied the effects of oral glutamine supplementation on endotoxemia, BT, liver and terminal ileal morphology, and apoptosis in an experimental model of obstructive jaundice. A total of 60 male Wistar rats were randomly divided into four groups of 15 each: I, controls; II, sham-operated; III, bile duct ligation (BDL); IV, BDL + glutamine (4.5 g/kg/day in drinking water). Ileal samples for histology, DNA and protein content, liver biopsies, mesenteric lymph nodes (MLNs) for culture, and portal and systemic blood samples for endotoxin measurements were obtained 10 days later. Compared to the controls, a significant increase in contaminated MLN and liver samples and increased endotoxemia were noted in group III (p < 0.01) but were significantly reduced in group IV (p < 0.05). Group IV also had a significantly higher number of mitoses per crypt (M/c) (p < 0.05), less apoptotic body counts (ABCs) (p < 0.05), and a higher DNA content than did group III (p < 0.05). Liver biopsies from group III displayed typical changes of large duct obstruction that significantly improved after glutamine treatment, with decreased ductular proliferation. We concluded that supplementation of oral glutamine in the presence of obstructive jaundice ameliorates BT, endotoxemia, and apoptosis and improves the ileal and liver histology.

Effect of oral glutamine administration on bacterial tanslocation, endotoxemia, liver and ileal morphology, and apoptosis in rats with obstructive jaundice

Postoperative complications in patients with obstructive jaundice remain increased when associated with endotoxemia and the inflammatory response due to gut barrier failure. Administration of glutamine has been proposed to maintain the integrity of the gut mucosa and thus reduce bacterial translocation (BT), but the effects of this pretreatment on apoptosis and histologic morphology of various organs affected by BT in obstructive jaundice have not been studied. We therefore studied the effects of oral glutamine supplementation on endotoxemia, BT, liver and terminal ileal morphology, and apoptosis in an experimental model of obstructive jaundice. A total of 60 male Wistar rats were randomly divided into four groups of 15 each: I, controls; II, sham-operated; III, bile duct ligation (BDL); IV, BDL + glutamine (4.5 g/kg/day in drinking water). Ileal samples for histology, DNA and protein content, liver biopsies, mesenteric lymph nodes (MLNs) for culture, and portal and systemic blood samples for endotoxin measurements were obtained 10 days later. Compared to the controls, a significant increase in contaminated MLN and liver samples and increased endotoxemia were noted in group III (p < 0.01) but were significantly reduced in group IV (p < 0.05). Group IV also had a significantly higher number of mitoses per crypt (M/c) (p < 0.05), less apoptotic body counts (ABCs) (p < 0.05), and a higher DNA content than did group III (p < 0.05). Liver biopsies from group III displayed typical changes of large duct obstruction that significantly improved after glutamine treatment, with decreased ductular proliferation. We concluded that supplementation of oral glutamine in the presence of obstructive jaundice ameliorates BT, endotoxemia, and apoptosis and improves the ileal and liver histology.

Evaluation of a glycine-rich amino acid solution for parenteral nutrition in endotoxemic rats

OBJECTIVE

It has been shown recently that high amounts of glycine might have some pharmacologic effects (reduction of injury and mortality in endotoxemic rats), but its effects on the nutritional status and protein metabolism during injury are still unknown. The aim of this study was to compare the nutritional effects of a glycine-rich amino acid solution for parenteral nutrition (AFD) with a standard one (Vintene) (glycine, 15 vs. 9 g/L) in endotoxemic rats.

DESIGN

Laboratory investigation.

SETTING

University laboratory.

SUBJECTS

Male Wistar rats (198 +/- 11 g).

INTERVENTIONS

Rats were operated to receive total parenteral nutrition (250 kcal/kg/day, 2 g N/kg/day) with amino acids supplied by either AFD (n = 9) or Vintene (V, n = 6). One day after surgery, corresponding to day 0 of the experiment and to the first day of full-strength total parenteral nutrition, the AFD and V group rats received an endotoxemic shock by intraperitoneal injection of lipopolysaccharide (Escherichia coli, 8 mg/kg). The rats were then studied over 3 days and compared with a healthy ad libitum-fed group (AL, n = 10).

MEASUREMENTS AND MAIN RESULTS

The rats were weighed and urine was collected daily to determine nitrogen balance and 3-methylhistidine excretion. On day 3, the thymus, spleen, liver, intestinal mucosa, and muscles were weighed, and amino acids from plasma and tissues were analyzed. Lipopolysaccharide caused the classic endotoxemic shock, of similar intensity in the V and AFD groups (V and AFD not equal AL, p < .05): no weight gain, decreased nitrogen balance (day 3, AL 558 +/- 21, V 83 +/- 28, AFD 123 +/- 25 mg N/day), increased urinary 3-methylhistidine/creatinine excretion (day 3, AL 51 +/- 2, V 91 +/- 13, AFD 87 +/- 14 mumol/mmol), soleus (V -15% and AFD -26 % vs. AL) and thymus atrophy (V -36% and AFD -33%), and spleen hypertrophy (V 51% and AFD 83%). Compared with V solution, AFD has a reduced content of some essential amino acids and proline and an elevated content of glycine, aspartate, and glutamate. These differences were not reflected in tissue or plasma amino acids, except for plasma glycine, which in the AFD group was restored to the level of the AL group (AL 426 +/- 12 and AFD 379 +/- 50 vs. V 251 +/- 31 mumol/L, p < .05).

CONCLUSIONS

In endotoxemic rats, the nutritional effects of a glycine-rich AFD solution are similar to those of a standard amino acid solution for parenteral nutrition.

The effect of L-tryptophan on hemorrhagic shock induced bacterial translocation1

Hemorrhagic shock causes mucosal damage in intestine and it results in translocation of bacteria to distant organs. In this study, effects of various doses of L-Tryptophan on the prevention of bacterial translocation in hemorrhagic shock induced rabbits were investigated. This study was carried out on six groups, each was consisting of 10 rabbits. While any procedure was conducted on the rabbits in group 1 (as a control group), 1 x 10(10)Escherichia coli isolate were administered rabbits in the other groups by gavage. In groups 3, 4, 5, and 6, hemorrhagic shock was induced. After induction of hemorrhagic shock, 10, 50, and 200 mg/kg L-Tryptophan were intragastrically administered to animals in groups 4, 5, and 6, respectively. Blood and terminal ileum samples were taken to detect bacterial translocation by polymerase chain reaction and mucosal damage by histopathological examination at 24 h after hemorrhagic shock. The occurrence of bacterial translocation increased as well when intestinal bacterial intensity was increased (P < 0.05). The most intensive bacterial translocation was formed in group 3 as a result of the additive effect of hemorrhagic shock to bacterial augmentation. It was observed that bacterial translocation was significantly reduced in groups 5 and 6 that are 50 and 200 mg/kg L-Tryptophan were administered (P < 0.01). Histopathological changes on mucosa and submucosa support these results. As a result, we concluded that augmentation of intestinal bacterial intensity induces bacterial translocation, the addition of hemorrhagic shock to bacterial augmentation makes more excessive translocation and mucosal changes have effective roles in these events. L-Tryptophan decreased the intestinal mucosal damage and bacterial translocation induced by hemorrhagic shock, in a dose-dependent manner.

Glutamine: recent developments in research on the clinical significance of glutamine

PURPOSE OF REVIEW

The aim of this review is to describe the clinical relevance of supplementation of glutamine from the recent literature. First, new basic research is examined and subsequently recent clinical trials and a metaanalysis are illustrated.

RECENT FINDINGS

Glutamine has a major impact on the functionality of the immune system. It has recently been established that glutamine not only has a protective effect on cells of the immune system, but also on other cells of the body, for instance cardiomyocytes. Evidence is accumulating for an effect of glutamine via glutathione, heat shock proteins as well as taurine. Another area of interest is the way glutamine enhances gut barrier function. More and more research is concentrating on the positive effect of glutamine on the gut-associated lymphoid tissue.

SUMMARY

Based on a recent meta-analysis and up-to-date clinical trials, we may conclude that glutamine has a beneficial effect on infectious complications and reduces hospital stay. In critically ill patients glutamine supplementation may reduce morbidity and mortality. The greatest effect was observed in patients receiving high dose parenteral glutamine. A recent study with high dose enteral glutamine demonstrated a reduced mortality in the glutamine supplemented group. In the future more trials with larger numbers of participants are needed, especially with high dose enteral glutamine in the perioperatively and the intensive care unit setting.

Glutamine and acute illness

This is a literature review over a time period of the past 2 years concerning glutamine in clinical nutrition. Emphasis is put upon studies of glutamine in clinical settings, but a brief overview of the large range of literature over the role of glutamine in various experimental settings is also included. The most interesting concept for the past 2 years is the suggestion to use plasma glutamine concentration at admission to the intensive care unit as a prognostic marker and as a possible indicator for indication of glutamine supplementation.

Role of L-glutamine in critical illness: new insights

PURPOSE OF REVIEW

This review will attempt to summarize recent clinical and experimental data on glutamine's use in critical illness. It will try to present the concept of glutamine as a 'drug' or 'nutraceutical', given in addition to standard nutritional support.

RECENT FINDINGS

Glutamine, traditionally considered to be a nonessential amino acid, is now considered as 'conditionally essential' following critical illness and injury. States of critical illness lead to significant decreases in plasma levels of glutamine and when this decrease is severe it has been correlated with increased mortality. Laboratory data have demonstrated numerous benefits of glutamine in experimental models of critical illness, including attenuated proinflammatory cytokine expression, improved gut barrier function, enhanced ability to mount a stress response, improved immune cell function, and decreased mortality. Over the last 10 years clinical trials of glutamine supplementation in critical illness have shown benefit with regard to mortality, length of stay, and infectious morbidity. However, data demonstrating a lack of benefit with glutamine supplementation in the critically ill have been presented as well. It appears that dose and route of administration clearly influence the benefit observed from glutamine administration, with high-dose, parenteral glutamine demonstrating an advantage over low-dose, enteral glutamine.

SUMMARY

High-dose or parenteral (>0.20-0.30 g/kg/day or > or =30 g/day) glutamine appears to demonstrate the greatest potential for benefit in critically ill patients. No evidence of harm has been observed in studies conducted to date, thus further clinical trials utilizing glutamine as a pharmacologic supplement to standard nutrition are warranted.