Parenteral nutrition is associated with intestinal morphologic and functional changes in humans

Patients requiring perioperative nutritional support

One of the most important factors affecting outcome and recovery from surgical trauma is preoperative nutritional status. Research in perioperative nutritional support has suffered from a lack of consensus as to the definition of malnutrition, no recognition of which nutrients are important to surgical healing, and a paucity of well-designed studies. In the past decade, there has been some activity to address this situation, recognizing the importance of nutrition as a therapy before surgery, after surgery, and possibly even during surgery.

The protective effect of VSL#3 on intestinal permeability in a rat model of alcoholic intestinal injury

Background

This study aimed to investigate the mechanism of the probiotic VSL#3 in acute alcoholic intestinal injury, and evaluate the effect of VSL#3, glutamine,VSL#3+glutamine and heat-killed VSL#3 therapy in a rat model.

Methods

Six- to eight-week-old male wild-type rats were divided into seven groups. To establish the acute alcohol liver disease model, rats received three doses of corn starch dissolved in PBS/40% alcohol administered intra-gastrically every 12 hours. Treatment groups received an intra-gastric dose of VSL#3, Glutamine, heat-killed VSL#3, or VSL#3+Glutamine 30 minutes prior to alcohol administration. The placebo group was treated with PBS prior to alcohol administration. TNFα and endotoxin in plasma was measured by ELISA and Tachypleus Ameboctye Lysate assays, and electron microscopy, Western blotting, and reverse transcription polymerase chain reaction were used to identify the mechanisms of VSL#3 in the regulation of epithelial permeability.

Results

First, compared with control group, endotoxin and TNFα in alcohol group was obviously high. At the same time, in VSL#3 group,the expression of endotoxin and TNFα obviously lower than the alcohol group. And the trends of the expression of tight junction proteins in these groups were reversed with the change of endotoxin and TNFα. Second, compared the groups of VSL#3 with glutamine,VSL#3+glutamine and heat-killed VSL#3,we found that both VSL#3 and heat-killed VSL#3, glutamine were as effective as VSL#3+glutamine in the treatment of acute alcohol liver disease, the expression of endotoxin and TNFα were lower than the alcohol group, and tight junction proteins were higher than the alcohol group whereas the expression of tight junction proteins were higher in VSL#3 + glutamine group than either agent alone, but have no significant difference.

Conclusion

We conclude that VSL#3 treatment can regulate the ecological balance of the gut microflora, preventing passage of endotoxin and other bacterial products from the gut lumen into the portal circulation and down-regulating the expression of TNFα, which could otherwise down-regulate the expression of tight junction proteins and increase epithelial permeability.

Enteral feeding during indomethacin and ibuprofen treatment of a patent ductus arteriosus

OBJECTIVE

To test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive "trophic" (15 mL/kg/d) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus.

STUDY DESIGN

Infants were eligible for the study if they were 23(1/7)-30(6/7) weeks' gestation, weighed 401-1250 g at birth, received maximum enteral volumes ≤60 mL/kg/d, and were about to be treated with indomethacin or ibuprofen. A standardized "feeding advance regimen" and guidelines for managing feeding intolerance were followed at each site (N = 13).

RESULTS

Infants (N = 177, 26.3 ± 1.9 weeks' mean ± SD gestation) were randomized at 6.5 ± 3.9 days to receive "trophic" feeds ("feeding" group, n = 81: indomethacin 80%, ibuprofen 20%) or no feeds ("fasting [nil per os]" group, n = 96: indomethacin 75%, ibuprofen 25%) during the drug administration period. Maximum daily enteral volumes before study entry were 14 ± 15 mL/kg/d. After drug treatment, infants randomized to the "feeding" arm required fewer days to reach the study's feeding volume end point (120 mL/kg/d). Although the enteral feeding end point was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the 2 groups. There were no differences between the 2 groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation, or other neonatal morbidities.

CONCLUSION

Infants required less time to reach the feeding volume end point if they were given "trophic" enteral feedings when they received indomethacin or ibuprofen treatments.

Tumour necrosis factor--induced loss of intestinal barrier function requires TNFR1 and TNFR2 signalling in a mouse model of total parenteral nutrition

Tumour necrosis factor-α (TNF-α) has been reported to play a central role in intestinal barrier dysfunction in many diseases; however, the precise role of the TNF-α receptors (TNFRs) has not been well defined using in vivo models. Our previous data showed that enteral nutrient deprivation or total parenteral nutrition (TPN) led to a loss of intestinal epithelial barrier function (EBF), with an associated upregulation of TNF-α and TNFR1. In this study, we hypothesized that TNF-α plays an important role in TPN-associated EBF dysfunction. Using a mouse TPN model, we explored the relative roles of TNFR1 vs. TNFR2 in mediating this barrier loss. C57/BL6 mice underwent intravenous cannulation and were given enteral nutrition or TPN for 7 days. Tumour necrosis factor-α receptor knockout (KO) mice, including TNFR1KO, TNFR2KO or TNFR1R2 double KO (DKO), were used. Outcomes included small intestine transepithelial resistance (TER) and tracer permeability, junctional protein zonula occludens-1, occludin, claudins and E-cadherin expression. In order to address the dependence of EBF on TNF-α further, exogenous TNF-α and pharmacological blockade of TNF-α (Etanercept) were also performed. Total parenteral nutrition led to a loss of EBF, and this was almost completely prevented in TNFR1R2DKO mice and partly prevented in TNFR1KO mice but not in TNFR2KO mice. The TPN-associated downregulation of junctional protein expression and junctional assembly was almost completely prevented in the TNFR1R2DKO group. Blockade of TNF-α also prevented dysfunction of the EBF and junctional protein losses in mice undergoing TPN. Administration of TPN upregulated the downstream nuclear factor-B and myosin light-chain kinase (MLCK) signalling, and these changes were almost completely prevented in TNFR1R2DKO mice, as well as with TNF-α blockade, but not in TNFR1KO or TNFR2KO TPN groups. Tumour necrosis factor-α is a critical factor for TPN-associated epithelial barrier dysfunction, and both TNFR1 and TNFR2 are involved in EBF loss. Nuclear factor-B and MLCK signalling appear to be important downstream mediators involved in this TNF-α signalling process.

Total parenteral nutrition-associated lamina propria inflammation in mice is mediated by a MyD88-dependent mechanism

Enteral nutrient deprivation via total parenteral nutrition (TPN) administration leads to local mucosal inflammatory responses, but the underlying mechanisms are unknown. Wild-type (WT) and MyD88(-/-) mice underwent jugular vein cannulation. One group received TPN without chow, and controls received standard chow. After 7 d, we harvested intestinal mucosally associated bacteria and isolated small-bowel lamina propria (LP) cells. Bacterial populations were analyzed using 454 pyrosequencing. LP cells were analyzed using quantitative PCR and multicolor flow cytometry. WT, control mucosally associated microbiota were Firmicutes-dominant, whereas WT TPN mice were Proteobacteria-domiant. Similar changes were observed in MyD88(-/-) mice with TPN administration. UniFrac analysis showed divergent small bowel and colonic bacterial communities in controls, merging toward similar microbiota (but distinct from controls) with TPN. The percentage of LP T regulatory cells significantly decreased with TPN in WT mice. F4/80(+)CD11b(+)CD11c(dull/-) macrophage-derived proinflammatory cytokines significantly increased with TPN. These proinflammatory immunologic changes were significantly abrogated in MyD88(-/-) TPN mice. Thus, TPN administration is associated with significant expansion of Proteobacteria within the intestinal microbiota and increased proinflammatory LP cytokines. Additionally, MyD88 signaling blockade abrogated decline in epithelial cell proliferation and epithelial barrier function loss.

Intestinal microbial diversity and perioperative complications

BACKGROUND AND AIMS

Enteral nutrient deprivation via parenteral nutrition (PN) in a mouse model leads to a local mucosal inflammatory response. This proinflammatory response leads to a loss of epithelial barrier function and atrophy of the intestine. Although the underlying mechanisms are unknown, a potential contributing factor is the impact PN has on the intestinal microbiome. We recently identified a shift in the intestinal microbial community in mice given PN; however, it is unknown whether such changes occur in humans. We hypothesized that similar microbial changes occur in humans during periods of enteral nutrient deprivation.

METHODS

A series of small bowel specimens were obtained from pediatric and adult patients undergoing small intestinal resection. Mucosally associated bacteria were harvested and analyzed using 454 pyrosequencing techniques. Statistical analysis of microbial diversity and differences in microbial characteristics were assessed between enterally fed and enterally deprived portions of the intestine. Occurrence of postoperative infectious and anastomotic complications was also examined.

RESULTS

Pyrosequencing demonstrated a wide variability in microbial diversity within all groups. Principal coordinate analysis demonstrated only a partial stratification of microbial communities between fed and enterally deprived groups. Interestingly, a tight correlation was identified in patients who had a low level of enteric microbial diversity and those who developed postoperative enteric-derived infections or intestinal anastomotic disruption.

CONCLUSIONS

Loss of enteral nutrients and systemic antibiotic therapy in humans is associated with a significant loss of microbial biodiversity within the small bowel mucosa. These changes were associated with a number of enteric-derived intestinal infections and intestinal anastomotic disruptions.

Advantages of enteral nutrition over parenteral nutrition

It is a strong and commonly held belief among nutrition clinicians that enteral nutrition is preferable to parenteral nutrition. We provide a narrative review of more recent studies and technical reviews comparing enteral nutrition with parenteral nutrition. Despite significant weaknesses in the existing data, current literature continues to support the use of enteral nutrition in patients requiring nutrition support, over parenteral nutrition.

Enteral nutrition discontinuation and outcomes in general critically ill patients

OBJECTIVE

To determine the relationship between enteral nutrition discontinuation and outcome in general critically ill patients.

MATERIALS AND METHODS

All patients admitted to a mixed intensive care unit in a tertiary care hospital from May-August 2009 were screened for an indication for enteral nutrition. Patients were followed up until leaving the intensive care unit or a maximum of 28 days. The gastrointestinal failure score was calculated daily by adding values of 0 if the enteral nutrition received was identical to the nutrition prescribed, 1 if the enteral nutrition received was at least 75% of that prescribed, 2 if the enteral nutrition received was between 50-75% of that prescribed, 3 if the enteral nutrition received was between 50-25% of that prescribed, and 4 if the enteral nutrition received was less than 25% of that prescribed.

RESULTS

The mean, worst, and categorical gastrointestinal failure scores were associated with lower survival in these patients. Age, categorical gastrointestinal failure score, type of admission, need for mechanical ventilation, sequential organ failure assessment, and Acute Physiologic and Chronic Health Evaluation II scores were selected for analysis with binary regression. In both models, the categorical gastrointestinal failure score was related to mortality.

CONCLUSION

The determination of the difference between prescribed and received enteral nutrition seemed to be a useful prognostic marker and is feasible to be incorporated into a gastrointestinal failure score.

Schlafen 3 changes during rat intestinal maturation

BACKGROUND

Understanding gut development may illuminate the adaptive response to massive small-bowel resection and facilitate enteral nutrition. We reported that Schlafen-3 (Slfn3) mediates differentiation in vitro in rat intestinal epithelial. We hypothesized that Slfn3 is involved in intestinal development in vivo.

METHODS

We removed fetal intestines, liver, and lungs on day 20 of gestation, at birth, and on postnatal days 1 and 5. Expression of Slfn3, markers of intestinal differentiation, and Slfn5, to address specificity, were determined by quantitative reverse-transcription polymerase chain reaction.

RESULTS

Villin expression increased on days 1 and 5 (8.7 ± .6 and 5.4 ± .4, respectively; P < .01). Intestinal Slfn3 expression was increased substantially after birth (2.1- ± .5-fold) and on days 1 and 5 (P < .02). Slfn3 was higher after birth in liver and lung but decreased sharply thereafter. Slfn5 expression was mostly unchanged.

CONCLUSIONS

The data suggest that the developmental/maturation effects we observed correlate with Slfn3 but not Slfn5 and are more relevant to the intestines. A better understanding of how Slfn3 promotes intestinal differentiation could help promote intestinal maturation, improving outcomes in children or adults with short-gut syndrome.

The protective effects of glutamine on radiation-induced diarrhea

INTRODUCTION

Glutamine is a neutral amino acid that is used by rapidly dividing cells such as erythrocytes, lymphocytes, and fibroblasts. It is also the substrate of glutathione synthesis. In normal metabolic rates, glutamine is an amino acid synthesized endogenously, but in high metabolic conditions such as cancer, it must be taken exogenously. Animal studies strongly demonstrate that glutamine protects both the upper and lower gastrointestinal tract mucosa from the effects of chemotherapy, radiotherapy, or other causes of injury. In this study, we investigated the protective effect of glutamine on radiation-induced diarrhea.

PATIENTS AND METHOD

The patients were divided into glutamine-treated and placebo groups. In the glutamine-treated group, 15 g of oral glutamine was administered three times daily. The patients were evaluated for diarrhea grade according to the National Cancer Institute Common Toxicity Criteria version 3.0, (Table 1), need for loperamide use, need for supportive parenteral therapy, and treatment breaks due to diarrhea.

RESULTS

There was no difference in overall diarrhea incidence when the two groups were compared. When diarrhea grade was evaluated, none of the patients in the glutamine-treated group had grade 3-4 diarrhea, but in the placebo group, grade 3-4 diarrhea was seen in 69 % of the patients. In the placebo-treated group, patients requiring loperamide and parenteral supportive therapy were 39 and 92 %, respectively. There was no treatment break in glutamine-treated patients.

CONCLUSION

Glutamine may have protective effect on radiation-induced severe diarrhea.

Changes in morphology and function in small intestinal mucosa after Roux-en-Y surgery in a rat model

BACKGROUND

Currently there is no an appropriate model to study intestinal mucosal atrophy in vivo that preserves the nutritional status of the organism.

MATERIALS AND METHODS

We created a defunctionalized segment of jejunum via a dead-end Roux-en-Y anastomosis in rats. We compared tissue morphometric parameters in the intestinal mucosa of the defunctionalized bowel with that of the mucosa proximal and distal to the anastomosis. We further measured extracellular signal-regulated kinase (ERK) activation within the mucosa as well as sucrase-isomaltase and dipeptidyl peptidase-4 levels as markers of intestinal mucosal differentiation by Western blotting of mucosal scrapings.

RESULTS

Three days after anastomosis, the defunctionalized bowel exhibited decreased diameter and thickness of both the mucosa and the fibromuscular layer compared with adjacent bowel in continuity for luminal nutrient flow or with bowel from control animals. Sucrase-isomaltase and dipeptidyl peptidase-4 levels also were decreased. Furthermore, mucosal ERK activation, assessed as the ratio of phosphorylated to total ERK, also was reduced. Animal weights did not differ between bypassed and control animals.

CONCLUSIONS

Deprivation of nutrient flow in a segment of bowel by defunctionalizing Roux-en-anastomosis produces mucosal atrophy as indicated by altered histology, differentiation marker expression, and ERK signaling, in animals that are otherwise able to maintain enteral nutrition.

Loss of enteral nutrition in a mouse model results in intestinal epithelial barrier dysfunction

Total parenteral nutrition (TPN) administration in a mouse model leads to a local mucosal inflammatory response, resulting in a loss of epithelial barrier function (EBF). Although, the underlying mechanisms are unknown, a major contributing factor is a loss of growth factors and subsequent critical downstream signaling. An important component of these is the p-Akt pathway. An additional contributing factor to the loss of EBF with TPN is an increase in proinflammatory cytokine abundance within the mucosal epithelium, including TNF-α and IFN-γ. Loss of critical nutrients, including glutamine and glutamate, may affect EBF, contributing to the loss of tight junction proteins. Finding protective modalities for the small intestine during TPN administration may have important clinical applications. Supplemental glutamine and glutamate may be examples of such agents.

Cholestasis and growth in neonates with gastroschisis

PURPOSE

The aim of this study was to determine the incidence of cholestasis and the correlation between cholestasis and weight-for-age z scores in parenteral nutrition-dependent neonates with gastroschisis.

METHODS

A single-center retrospective review of 59 infants born with gastroschisis from January 2000 to June 2007 was conducted. Demographic and clinical data were collected and analyzed. Subjects were divided into cholestatic and noncholestatic groups. Statistical analyses included the Student t test, Wilcoxon rank sum test, Fisher exact test, and a general linear model.

RESULTS

Fifty-nine neonates with gastroschisis were identified, and 16 (28%) of 58 patients developed cholestasis. Younger gestational age and cholestasis were found to be independently associated with weight-for-age z score in 30 of 58 patients with available long-term follow-up data.

CONCLUSIONS

Parenteral nutrition-dependent neonates with gastroschisis remain at considerable risk for the development of cholestasis. Both gestational age and cholestasis were found to be independent risk factors, predisposing these neonates to poor postnatal growth.

Glutamine and whey protein improve intestinal permeability and morphology in patients with Crohn's disease: a randomized controlled trial

BACKGROUND

Increased intestinal permeability (IP) has been implicated in the etiopathogenesis, disease activity and relapse of Crohn's disease (CD). Glutamine, the major fuel for the enterocytes, may improve IP.

AIM

We evaluated the effect of oral glutamine on IP and intestinal morphology in patients with CD.

METHODS

In a randomized controlled trial, consecutive patients with CD in remission phase with an abnormal IP were randomized to a glutamine group (GG) or active control group (ACG) and were given oral glutamine or whey protein, respectively, as 0.5 g/kg ideal body weight/day for 2 months. IP was assessed by the lactulose mannitol excretion ratio (LMR) in urine, and morphometry was performed by computerized image analysis system.

RESULTS

Patients (age 34.5 ± 10.5 years; 20 males) were assigned to the GG (n = 15) or ACG (n = 15). Fourteen patients in each group completed the trial. The LMR [median (range)] in GG and ACG at 2 months was 0.029 (0.006-0.090) and 0.033 (0.009-0.077), respectively, with P = 0.6133. IP normalized in 8 (57.1%) patients in each group (P = 1.000). The villous crypt ratio (VCR) [mean (SD)] in GG and ACG at 2 months was 2.68 (1.02) and 2.49 (0.67), respectively, (P = 0.347). At the end of 2 months LMR improved significantly in GG from 0.071 (0.041-0.254) to 0.029 (0.006-0.090) (P = 0.0012) and in ACG from 0.067 (0.040-0.136) to 0.033 (0.009-0.077) (P = 0.0063). VCR improved in the GG from 2.33 (0.77) to 2.68 (1.02) (P = 0.001), and in ACG from 2.26 (0.57) to 2.49 (0.67) (P = 0.009).

CONCLUSIONS

Intestinal permeability and morphology improved significantly in both glutamine and ACG.

Insulin-like growth factor 1: common mediator of multiple enterotrophic hormones and growth factors

PURPOSE OF REVIEW

To summarize the recent evidence that insulin-like growth factor 1 (IGF1) mediates growth effects of multiple trophic factors and discuss clinical relevance.

RECENT FINDINGS

Recent reviews and original reports indicate benefits of growth hormone (GH) and long-acting glucagon-like peptide 2 (GLP2) analogs in short bowel syndrome and Crohn's disease. This review highlights the evidence that biomarkers of sustained small intestinal growth or mucosal healing and evaluation of intestinal epithelial stem cell biomarkers may improve clinical measures of intestinal growth or response to trophic hormones. Compelling evidence that IGF1 mediates growth effects of GH and GLP2 on intestine or linear growth in preclinical models of resection or Crohn's disease is presented, along with a concept that these hormones or IGF1 may enhance sustained growth if given early after bowel resection. Evidence that suppressor of cytokine signaling protein induction by GH or GLP2 in normal or inflamed intestine may limit IGF1-induced growth, but protect against risk of dysplasia or fibrosis, is reviewed. Whether IGF1 receptor mediates IGF1 action and potential roles of insulin receptors are addressed.

SUMMARY

IGF1 has a central role in mediating trophic hormone action in small intestine. Better understanding of benefits and risks of IGF1, receptors that mediate IGF1 action, and factors that limit undesirable growth are needed.

Bloodstream infections in very low birth weight infants with intestinal failure

OBJECTIVE

To examine pathogens and other characteristics associated with late-onset bloodstream infections (BSIs) in infants with intestinal failure (IF) as a consequence of necrotizing enterocolitis (NEC).

STUDY DESIGN

Infants weighing 401-1500 g at birth who survived for >72 hours and received care at Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network centers were studied. The frequency of culture-positive BSI and pathogens were compared in infants with medically managed NEC, NEC managed surgically without IF, and surgical IF. Among infants with IF, the duration of parenteral nutrition (PN) and other outcomes were evaluated.

RESULTS

A total of 932 infants were studied (IF, n = 78; surgical NEC without IF, n = 452; medical NEC, n = 402). The proportion with BSI after diagnosis of NEC was higher in the infants with IF than in those with surgical NEC (P = .007) or medical NEC (P < .001). Gram-positive pathogens were most frequent. Among infants with IF, an increased number of infections was associated with longer hospitalization and duration of PN (median stay: 172 for those with 0 infections, 188 days for those with 1 infection, and 260 days for those with ≥2 infections [P = .06]; median duration of PN: 90, 112, and 115 days, respectively [P = .003]) and decreased achievement of full feeds during hospitalization (87%, 67%, and 50%, respectively; P = .03).

CONCLUSION

Recurrent BSIs are common in very low birth weight infants with IF. Gram-positive bacteria were the most commonly identified organisms in these infants.

The relationships of nutrients, routes of delivery, and immunocompetence

Malnutrition has marked consequences on surgical outcomes. Adequate nutrition is important for the proper functioning of all organ systems, particularly the immune system. Determination of the type and amount of nutrient supplementation and the appropriate route of nutrient delivery is essential to bolster the immune system and enhance the host's response to stress. Correct administration of immunonutrients could lead to reductions in patient morbidity following major surgery, trauma, and critical illness.

Approaches to intestinal failure in Crohn's disease

Crohn's disease is one of the leading causes of intestinal failure. The term ‘type 2’ intestinal failure is used to describe the relatively rare type of intestinal failure that occurs in association with septic, metabolic and complex nutritional complications, typically following surgical resection and/or laparostomy for intra-abdominal sepsis. A multidisciplinary approach to the management of patients with type 2 intestinal failure is crucial, and it is helpful to approach patient care in a structured manner using the ‘sepsis-nutrition-anatomy-plan’ algorithm: resolution ofsepsis is required before adequate nutritional repletion can be achieved, and it is crucial to optimise nutritional status, and define intestinal anatomy before delineating a definitive medical or surgical plan. A structured approach to the management of patients with inflammatory bowel disease, who have developed type 2 intestinal failure, should reduce the likelihood of these patients developing ‘type 3’ intestinal failure, which is characterised by the need for long-term parenteral nutrition. However, Crohn's disease is still the commonest indication for home parenteral nutrition in the UK.

Duodenal-jejunal bypass protects GK rats from {beta}-cell loss and aggravation of hyperglycemia and increases enteroendocrine cells coexpressing GIP and GLP-1

Dramatic improvement of type 2 diabetes is commonly observed after bariatric surgery. However, the mechanisms behind the alterations in glucose homeostasis are still elusive. We examined the effect of duodenal-jejunal bypass (DJB), which maintains the gastric volume intact while bypassing the entire duodenum and the proximal jejunum, on glycemic control, β-cell mass, islet morphology, and changes in enteroendocrine cell populations in nonobese diabetic Goto-Kakizaki (GK) rats and nondiabetic control Wistar rats. We performed DJB or sham surgery in GK and Wistar rats. Blood glucose levels and glucose tolerance were monitored, and the plasma insulin, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) levels were measured. β-Cell area, islet fibrosis, intestinal morphology, and the density of enteroendocrine cells expressing GLP-1 and/or GIP were quantified. Improved postprandial glycemia was observed from 3 mo after DJB in diabetic GK rats, persisting until 12 mo after surgery. Compared with the sham-GK rats, the DJB-GK rats had an increased β-cell area and a decreased islet fibrosis, increased insulin secretion with increased GLP-1 secretion in response to a mixed meal, and an increased population of cells coexpressing GIP and GLP-1 in the jejunum anastomosed to the stomach. In contrast, DJB impaired glucose tolerance in nondiabetic Wistar rats. In conclusion, although DJB worsens glucose homeostasis in normal nondiabetic Wistar rats, it can prevent long-term aggravation of glucose homeostasis in diabetic GK rats in association with changes in intestinal enteroendocrine cell populations, increased GLP-1 production, and reduced β-cell deterioration.

Effects of adding butyric acid to PN on gut-associated lymphoid tissue and mucosal immunoglobulin A levels

BACKGROUND

Parenteral nutrition (PN) causes intestinal mucosal atrophy, gut-associated lymphoid tissue (GALT) atrophy and dysfunction, leading to impaired mucosal immunity and increased susceptibility to infectious complications. Therefore, new PN formulations are needed to maintain mucosal immunity. Short-chain fatty acids have been demonstrated to exert beneficial effects on the intestinal mucosa. We examined the effects of adding butyric acid to PN on GALT lymphocyte numbers, phenotypes, mucosal immunoglobulin A (IgA) levels, and intestinal morphology in mice.

METHODS

Male Institute of Cancer Research mice (n = 103) were randomized to receive either standard PN (S-PN), butyric acid-supplemented PN (Bu-PN), or ad libitum chow (control) groups. The mice were fed these respective diets for 5 days. In experiment 1, cells were isolated from Peyer's patches (PPs) to determine lymphocyte numbers and phenotypes (αβTCR(+), γδTCR(+), CD4(+), CD8(+), B220(+) cells). IgA levels in small intestinal washings were also measured. In experiment 2, IgA levels in respiratory tract (bronchoalveolar and nasal) washings were measured. In experiment 3, small intestinal morphology was evaluated.

RESULTS

Lymphocyte yields from PPs and small intestinal, bronchoalveolar, and nasal washing IgA levels were all significantly lower in the S-PN group than in the control group. Bu-PN moderately, but significantly, restored PP lymphocyte numbers, as well as intestinal and bronchoalveolar IgA levels, as compared with S-PN. Villous height and crypt depth in the small intestine were significantly decreased in the S-PN group vs the control group, however Bu-PN restored intestinal morphology.

CONCLUSIONS

A new PN formula containing butyric acid is feasible and would ameliorate PN-induced impairment of mucosal immunity.

K-cells and glucose-dependent insulinotropic polypeptide in health and disease

In the 1970s, glucose-dependent insulinotropic polypeptide (GIP, formerly gastric inhibitory polypeptide), a 42-amino acid peptide hormone, was discovered through a search for enterogastrones and subsequently identified as an incretin, or an insulinotropic hormone secreted in response to intraluminal nutrients. Independent of the discovery of GIP, the K-cell was identified in small intestine by characteristic ultrastructural features. Subsequently, it was realized that K-cells are the predominant source of circulating GIP. The density of K-cells may increase under conditions including high-fat diet and obesity, and generally correlates with plasma GIP levels. In addition to GIP, K-cells secrete xenin, a peptide with as of yet poorly understood physiological functions, and GIP is often colocalized with the other incretin hormone glucagon-like peptide-1 (GLP-1). Differential posttranslational processing of proGIP produces 30 and 42 amino acid versions of GIP. Its secretion is elicited by intraluminal nutrients, especially carbohydrate and fat, through the action of SGLT1, GPR40, GPR120, and GPR119. There is also evidence of regulation of GIP secretion via neural pathways and somatostatin. Intracellular signaling mechanisms of GIP secretion are still elusive but include activation of adenylyl cyclase, protein kinase A (PKA), and protein kinase C (PKC). GIP has extrapancreatic actions on adipogenesis, neural progenitor cell proliferation, and bone metabolism. However, the clinical or physiological relevance of these extrapancreatic actions remain to be defined in humans. The application of GIP as a glucose-lowering drug is limited due to reduced efficacy in humans with type 2 diabetes and its potential obesogenic effects demonstrated by rodent studies. There is some evidence to suggest that a reduction in GIP production or action may be a strategy to reduce obesity. The meal-dependent nature of GIP release makes K-cells a potential target for genetically engineered production of satiety factors or glucose-lowering agents, for example, insulin. Transgenic mice engineered to produce insulin from intestinal K-cells are resistant to diabetes induced by a beta-cell toxin. Collectively, K-cells and GIP play important roles in health and disease, and both may be targets for novel therapies.

Acute lung injury: epidemiology, pathogenesis, and treatment

Acute lung injury (ALI) remains a significant source of morbidity and mortality in the critically ill patient population. Defined by a constellation of clinical criteria (acute onset of bilateral pulmonary infiltrates with hypoxemia without evidence of hydrostatic pulmonary edema), ALI has a high incidence (200,000 per year in the US) and overall mortality remains high. Pathogenesis of ALI is explained by injury to both the vascular endothelium and alveolar epithelium. Recent advances in the understanding of pathophysiology have identified several biologic markers that are associated with worse clinical outcomes. Phase III clinical trials by the NHLBI ARDS Network have resulted in improvement in survival and a reduction in the duration of mechanical ventilation with a lung-protective ventilation strategy and fluid conservative protocol. Potential areas of future treatments include nutritional strategies, statin therapy, and mesenchymal stem cells.

Artificial nutrition: principles and practice of enteral feeding

Enteral feeding is a commonly used form of nutritional supplementation for patients with intestinal failure, both in hospitals and in the community. This article concentrates on the basic principles of enteral feeding, including the physiological effects of feeding into the intestinal tract. It covers the indications for enteral feeding, the different methods of supplying enteral feeds to the gastrointestinal tract, and the potential complications. There is also a discussion of the indications for and practice of home enteral nutrition.

Development of Crohn's disease in patients with intestinal failure: a role for bacteria?

We present 3 cases of Crohn's disease that developed in patients with previously diagnosed short bowel syndrome from another cause. There are characteristics unique to patients with short bowel syndrome that may increase their likelihood to develop Crohn's disease, based on current concepts of the pathophysiology of inflammatory bowel disease. These patients may have a higher than average prevalence of small intestinal bacterial overgrowth. This may lead to an increase in bacterial translocation and dysregulation of the intestinal immune response. In addition, these patients often require parenteral nutrition (PN) because of macronutrient and micronutrient deficiencies. Some patients receiving PN, particularly those with bowel obstructions, may be at risk for septicemia due to bacterial translocation. It is thought that PN may enhance intestinal dysmotility and impair gut immunity, contributing further to an antigenic immune response in the intestinal immune system, although supporting data is lacking. Finally, studies have demonstrated that patient's with Crohn's disease have a shorter bowel length before any intestinal resections and not related to disease activity. Although the significance of this is unclear, a shorter bowel length may potentially predispose people to the development of Crohn's disease via an alteration of intestinal motility and intestinal flora.

New insights into the development of retinopathy of prematurity--importance of early weight gain

Evidence is accumulating that one of the strongest predictors of retinopathy of prematurity (ROP), in addition to low gestational age, is poor weight gain during the first weeks of life. In infants born preterm, the retina is not fully vascularised. The more premature the child, the larger is the avascular area. In response to hypoxia, vascular endothelial growth factor (VEGF) is secreted. For appropriate VEGF-induced vessel growth, sufficient levels of insulin-like growth factor I (IGF-I) in serum are necessary. IGF-I is a peptide, related to nutrition supply, which is essential for both pre- and post-natal general growth as well as for growth of the retinal vasculature. In prematurely born infants, serum levels are closely related to gestational age and are lower in more prematurely born infants. At preterm birth the placental supply of nutrients is lost, growth factors are suddenly reduced and general as well as vascular growth slows down or ceases. In addition, the relative hyperoxia of the extra-uterine milieu, together with supplemental oxygen, causes a regression of already developed retinal vessels. Postnatal growth retardation is a major problem in very preterm infants. Both poor early weight gain and low serum levels of IGF-I during the first weeks/months of life have been found to be correlated with severity of ROP.

CONCLUSION

This review will focus on the mechanisms leading to ROP by exploring factors responsible for poor early weight gain and abnormal vascularisation of the eye of the preterm infant.

Enteral versus parenteral nutrition for acute pancreatitis

BACKGROUND

Acute pancreatitis creates a catabolic stress state promoting a systemic inflammatory response and nutritional deterioration. Adequate supply of nutrients plays an important role in recovery. Total parenteral nutrition (TPN) has been standard practice for providing exogenous nutrients to patients with severe acute pancreatitis. However, recent data suggest that enteral nutrition (EN) is not only feasible, but safer and more effective.Therefore, we sought to update our systematic review to re-evaluate the level of evidence.

OBJECTIVES

To compare the effect of TPN versus EN on mortality, morbidity and length of hospital stay in patients with acute pancreatitis.

SEARCH STRATEGY

Trials were identified by computerized searches of The Cochrane Controlled Trials Register, MEDLINE, and EMBASE. Additional studies were identified by searching Scisearch, bibliographies of review articles and identified trials. The search was undertaken in August 2000 and updated in September 2002, October 2003, November 2004 and November 2008. No language restrictions were applied.

SELECTION CRITERIA

Randomized clinical trials comparing TPN to EN in patients with acute pancreatitis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed trial quality. A standardized form was used to extract relevant data.

MAIN RESULTS

Eight trials with a total of 348 participants were included. Comparing EN to TPN for acute pancreatitis, the relative risk (RR) for death was 0.50 (95% CI 0.28 to 0.91), for multiple organ failure (MOF) was 0.55 (95% CI 0.37 to 0.81), for systemic infection was 0.39 (95% CI 0.23 to 0.65), for operative interventions was 0.44 (95% CI 0.29 to 0.67), for local septic complications was 0.74 (95% CI 0.40 to 1.35), and for other local complications was 0.70 (95% CI 0.43 to 1.13). Mean length of hospital stay was reduced by 2.37 days in EN vs TPN groups (95% CI -7.18 to 2.44). Furthermore, a subgroup analysis for EN vs TPN in patients with severe acute pancreatitis showed a RR for death of 0.18 (95% CI 0.06 to 0.58) and a RR for MOF of 0.46 (95% CI 0.16 to 1.29).

AUTHORS' CONCLUSIONS

In patients with acute pancreatitis, enteral nutrition significantly reduced mortality, multiple organ failure, systemic infections, and the need for operative interventions compared to those who received TPN. In addition, there was a trend towards a reduction in length of hospital stay. These data suggest that EN should be considered the standard of care for patients with acute pancreatitis requiring nutritional support.

Complications and monitoring - Guidelines on Parenteral Nutrition, Chapter 11

Compared to enteral or hypocaloric oral nutrition, the use of PN (parenteral nutrition) is not associated with increased mortality, overall frequency of complications, or longer length of hospital stay (LOS). The risk of PN complications (e.g. refeeding-syndrome, hyperglycaemia, bone demineralisation, catheter infections) can be minimised by carefully monitoring patients and the use of nutrition support teams particularly during long-term PN. Occuring complications are e.g. the refeeding-syndrome in patients suffering from severe malnutrition with the initiation of refeeding or metabolic, hypertriglyceridemia, hyperglycaemia, osteomalacia and osteoporosis, and hepatic complications including fatty liver, non-alcoholic fatty liver disease, cholestasis, cholecystitis, and cholelithiasis. Efficient monitoring in all types of PN can result in reduced PN-associated complications and reduced costs. Water and electrolyte balance, blood sugar, and cardiovascular function should regularly be monitored during PN. Regular checks of serum electrolytes and triglycerides as well as additional monitoring measures are necessary in patients with altered renal function, electrolyte-free substrate intake, lipid infusions, and in intensive care patients. The metabolic monitoring of patients under long-term PN should be carried out according to standardised procedures. Monitoring metabolic determinants of bone metabolism is particularly important in patients receiving long-term PN. Markers of intermediary, electrolyte and trace element metabolism require regular checks.

Organisation, regulations, preparation and logistics of parenteral nutrition in hospitals and homes; the role of the nutrition support team - Guidelines on Parenteral Nutrition, Chapter 8

PN (parenteral nutrition) should be standardised to ensure quality and to reduce complications, and it should be carried out in consultation with a specialised nutrition support team whenever possible. Interdisciplinary nutrition support teams should be established in all hospitals because effectiveness and efficiency in the implementation of PN are increased. The tasks of the team include improvements of quality of care as well as enhancing the benefit to cost ratio. Therapeutic decisions must be taken by attending physicians, who should collaborate with the nutrition support team. “All-in-One” bags are generally preferred for PN in hospitals and may be industrially manufactured, industrially manufactured with the necessity to add micronutrients, or be prepared “on-demand” within or outside the hospital according to a standardised or individual composition and under consideration of sterile and aseptic conditions. A standardised procedure should be established for introduction and advancement of enteral or oral nutrition. Home PN may be indicated if the expected duration of when PN exceeds 4 weeks. Home PN is a well established method for providing long-term PN, which should be indicated by the attending physician and be reviewed by the nutrition support team. The care of home PN patients should be standardised whenever possible. The indication for home PN should be regularly reviewed during the course of PN.

The bone morphogenetic protein signaling pathway is upregulated in a mouse model of total parenteral nutrition

Total parenteral nutrition (TPN) results in intestinal mucosal atrophic changes due to an absence of enteral nutrition; however, the mechanisms responsible for this are not fully understood. It has been shown that bone morphogenetic protein (BMP) activation inhibits intestinal epithelial cell (EC) proliferation. Therefore, we hypothesized that the BMP pathway could be upregulated by TPN. To address this, we randomly assigned mice to receive TPN or to be enterally fed (control) for 7 d. Mucosal EC isolates were harvested from the entire length of small intestine for RNA and protein measurements. Full-thickness, mid-small bowel was processed for histological examination. TPN increased the abundance of BMP2, BMP4, and BMP type II receptor at the RNA and protein levels. Phosphorylation of Smad1, Smad5, and Smad8 also was greater in the TPN group than in the control, which helped to confirm activation of this pathway. Interestingly, the TPN and control groups did not differ in the mRNA expression of the extracellular soluble bmp antagonists, noggin, gremlin, chordin, or follistatin. Compared to the control group, the expression of c-Myc (cellular myelocytomatosis) mRNA was lower, whereas the level of p21(WAF1/CIP1) was greater, in the TPN group. Because the BMP family may function through suppression of Wnt-beta-catenin signaling, this pathway was also examined. mRNA expression of Wnt 3, Wnt5a, and the Wnt receptor Lrp5 were lower in the TPN group compared to controls. The results suggest that the BMP signaling pathway may be involved in the development of intestinal mucosal atrophy due to TPN administration.

Enteral versus parenteral nutrition: effect on intestinal barrier function

Total parenteral nutrition (TPN), or the complete absence of enteral nutrients, is commonly used in a clinical setting. However, a major consequence of TPN administration is the development of mucosal atrophy and a loss of epithelial barrier function (EBF); and this loss may lead to an increase in clinical infections and septicemia. Our laboratory has investigated the mechanism of this TPN-associated loss of EBF using a mouse model. We have demonstrated that the mucosal lymphoid population significantly changes with TPN, and leads to a rise in interferon gamma (IFN-gamma) and decline in interleukin-10 (IL-10) expression-both of which contribute to the loss of EBF. Associated with these cytokine changes is a dramatic decline in the expression of tight junction and adherens junction proteins. This article discusses the potential mechanisms responsible for these changes, and potential strategies to alleviate this loss in EBF.

Glutamine increases autophagy under Basal and stressed conditions in intestinal epithelial cells

BACKGROUND & AIMS

Glutamine plays a protective role in intestinal cells during physiologic stress; however, the protection mechanisms are not fully understood. Autophagy functions in bulk degradation of cellular components, but has been recognized recently as an important mechanism for cell survival under conditions of stress. We therefore sought to see if glutamine's actions involve the induction of autophagy in intestinal cells and, if so, the mechanisms that underlie this action.

METHODS

Formation of microtubule-associated protein light chain 3 (LC3)-phospholipid conjugates (LC3-II) in rat intestinal epithelial IEC-18 cells and human colonic epithelial Caco-2(BBE) cells was determined by Western blotting and localized by confocal microscopy. Activation of mammalian target of rapamycin (mTOR) pathway, mitogen-activated protein (MAP) kinases, caspase-3, and poly (ADP-ribose) polymerase were monitored by Western blotting.

RESULTS

Glutamine increased LC3-II as well as the number of autophagosomes. Glutamine-induced LC3-II formation was paralleled by inactivation of mTOR and p38 MAP kinase pathways, and inhibition of mTOR and p38 MAP kinase allowed LC3-II induction in glutamine-deprived cells. Under glutamine starvation, LC3-II recovery after heat stress or the increase under oxidative stress was blunted significantly. Glutamine depletion increased caspase-3 and poly (ADP-ribose) polymerase activity after heat stress, which was inhibited by treatment with inhibitors of mTOR and p38 MAP kinase.

CONCLUSIONS

Glutamine induces autophagy under basal and stressed conditions, and prevents apoptosis under heat stress through its regulation of the mTOR and p38 MAP kinase pathways. We propose that glutamine contributes to cell survival during physiologic stress by induction of autophagy.

Avaliação de um esquema de realimentação utilizado após 43 dias de jejum voluntário

OBJETIVO: Avaliar um esquema de realimentação utilizado em pacientes após jejum prolongado voluntário. MÉTODOS: Foi realizado estudo retrospectivo, com base em levantamento dos prontuários de 7 pacientes (média de idade de 41,6 anos e desvio-padrão=5,3) em jejum voluntário por 43 dias em jejum seguidos de 14 dias de realimentação. As variáveis estudadas foram: antropométricas, clínicas, dietéticas, laboratoriais e avaliação da composição corpórea por bioimpedância. Foram utilizadas as seguintes dietas por via oral na realimentação: oligomérica enriquecida com glutamina, associada à dieta hipogordurosa e isenta de lactose (primeira semana); dieta branda normolipídica com lactose (segunda semana). A análise descritiva dos dados apresentados incluiu média e desvio-padrão. A análise de variância ou o teste não paramétrico de Kruskal-Wallis foram utilizados para comparação dos dados nos períodos de jejum e realimentação. Utilizou-se o programa estatístico SIGMA STAT versão 2,03 sendo considerado o nível de significância de 5%. RESULTADOS: No jejum houve redução significativa do peso corpóreo (18,0% desvio-padrão=2,3), da prega cutânea do tríceps (48,2% desvio-padrão=9,0) e da hemoglobina (15,98g/dL desvio-padrão=0,99 para 12,74g/dL desvio-padrão=0,47). Na segunda semana de realimentação houve aumento significativo na contagem total de linfócitos (954 mil/mm³ desvio-padrão=242 para 1.619 mil/mm³ desvio-padrão=232) e dos distúrbios gastrointestinais, em relação à primeira semana. Não ocorreu Síndrome da Realimentação. CONCLUSÃO: O esquema de realimentação utilizado promoveu resultado global adequado, mas requer redução do aporte energético e definição de momento mais adequado para reintrodução de lactose e da dieta normolipídica.

Nutrient intake from habitual oral diet in patients with severe short bowel syndrome living in the southeastern United States

OBJECTIVES

Little data are published on the habitual home oral diet of patients with short bowel syndrome (SBS).

METHODS

We assessed nutrient intake from oral food and beverages in 19 stable patients with severe SBS who live in the southeastern United States. Intestinal absorption of energy, fat, nitrogen (N), and carbohydrate (CHO) was determined in a metabolic ward.

RESULTS

We studied 12 women and 7 men, age 48 +/- 3 y of age (mean +/- SE) receiving parenteral nutrition for 31 +/- 8 mo following massive small bowel resection (118 +/- 25 cm residual small bowel). The patients demonstrated severe malabsorption of energy (59 +/- 3% of oral intake), fat (41 +/- 5%), N (42 +/- 5%) and CHO (76 +/- 3%). Oral energy intake was 2656 +/- 242 kcal/d (39 +/- 3 kcal/kg/d) and oral protein intake was 1.4 +/- 0.1 g/kg/d. Food/beverage intake constituted 49 +/- 4% of total (enteral plus parenteral) daily fluid intake, 66 +/- 4% of total daily kcal and 58 +/- 5% of total daily N intake. Oral fat intake averaged 92 +/- 11 g/day ( approximately 35% of total oral energy). Oral fluid intake averaged 2712 +/- 240 ml/d, primarily from water, soft drinks, sweet tea and coffee. Simple sugars comprised 42 +/- 3% of oral CHO intake. Usual dietary intake of multiple micronutrients were below the Recommended Dietary Allowances (RDA) in a large percentage of patients: vitamin A (47%), vitamin D (79%), vitamin E (79%), vitamin K (63%), thiamine (42%), vitamin B6 (68%), vitamin B12 (11%), vitamin C (58%), folate (37%), iron (37%), calcium (63%), magnesium (79%) and zinc (68%). Only seven patients (37%) were taking oral multivitamin-mineral supplements and only six subjects (32%) were taking oral iron and calcium supplements, respectively.

CONCLUSION

In these SBS patients, an oral diet provided a significant proportion of daily nutrient intake. The types of foods and fluids consumed are likely to worsen malabsorption and thus increase PN requirements. Oral intake of essential micronutrients was very low in a significant proportion of these individuals.

Intestinal alkaline phosphatase is a gut mucosal defense factor maintained by enteral nutrition

Under conditions of starvation and disease, the gut barrier becomes impaired, and trophic feeding to prevent gut mucosal atrophy has become a standard treatment of critically ill patients. However, the mechanisms responsible for the beneficial effects of enteral nutrition have remained a mystery. Using in vitro and in vivo models, we demonstrate that the brush-border enzyme, intestinal alkaline phosphatase (IAP), has the ability to detoxify lipopolysaccharide and prevent bacterial invasion across the gut mucosal barrier. IAP expression and function are lost with starvation and maintained by enteral feeding. It is likely that the IAP silencing that occurs during starvation is a key component of the gut mucosal barrier dysfunction seen in critically ill patients.

Molecular mechanisms contributing to glutamine-mediated intestinal cell survival

Glutamine, the most abundant amino acid in the bloodstream, is the preferred fuel source for enterocytes and plays a vital role in the maintenance of mucosal growth. The molecular mechanisms regulating the effects of glutamine on intestinal cell growth and survival are poorly understood. Here, we show that addition of glutamine (1 mmol/l) enhanced rat intestinal epithelial (RIE)-1 cell growth; conversely, glutamine deprivation increased apoptosis as noted by increased DNA fragmentation and caspase-3 activity. To delineate signaling pathways involved in the effects of glutamine on intestinal cells, we assessed activation of extracellular signal-related kinase (ERK), protein kinase D (PKD), and phosphatidylinositol 3-kinase (PI3K)/Akt, which are important pathways in cell growth and survival. Addition of glutamine activated ERK and PKD in RIE-1 cells after a period of glutamine starvation; inhibition of ERK, but not PKD, increased cell apoptosis. Conversely, glutamine starvation alone increased phosphorylated Akt; inhibition of Akt enhanced RIE-1 cell DNA fragmentation. The role of ERK was further delineated using RIE-1 cells stably transfected with an inducible Ras. Apoptosis was significantly increased following ERK inhibition, despite Ras activation. Taken together, these results identify a critical role for the ERK signaling pathways in glutamine-mediated intestinal homeostasis. Furthermore, activation of PI3K/Akt during periods of glutamine deprivation likely occurs as a protective mechanism to limit apoptosis associated with cellular stress. Importantly, our findings provide novel mechanistic insights into the antiapoptotic effects of glutamine in the intestine.

Immediate oral feeding in patients with mild acute pancreatitis is safe and may accelerate recovery--a randomized clinical study

BACKGROUND & AIMS

In acute pancreatitis, traditional treatment has been initial fasting on purpose to avoid activation of proteolytic enzymes and pancreatic enzyme secretion. The aim of the present study was to evaluate the efficacy and feasibility of immediate oral feeding as compared to traditional fasting in patients with mild acute pancreatitis.

METHODS

Sixty patients were randomized to the two treatment groups, fasting or immediate oral feeding. The inclusion criteria were pancreas amylase > or =3 times above normal, onset of abdominal pain within 48 h, acute physiological and chronic health evaluation (APACHE) score<8 and C-reactive protein (CRP) <150 mg/L. Outcome measures were pancreas-specific amylase, systemic inflammatory response, feasibility and length of hospital stay (LOHS).

RESULTS

The groups were comparable with respect to age, sex, etiology, APACHE, time from onset of pain and amylase at admission. No significant differences were seen between the groups concerning levels of amylase, CRP, leukocytes, abdominal pain or number of gastrointestinal symptoms. The LOHS was significantly shorter in the oral feeding group (4 vs. 6 days; p<0.05).

CONCLUSIONS

No signs of exacerbation of the disease process were seen in terms of significant differences between treatment groups for amylase or systemic inflammatory response. In mild acute pancreatitis, immediate oral feeding was feasible and safe and may accelerate recovery without adverse gastrointestinal events.

Use of percutaneous endoscopic gastrostomy or percutaneous endoscopic jejunostomy in short bowel syndrome

Patients who have short bowel syndrome (SBS) and concomitant intestinal failure have insufficient functional capacity to absorb sufficient nutrients, electrolytes, and/or fluid to sustain independent life. As such, these patients require specialized nutritional support. Although parenteral nutrition is often necessary, at least initially, the therapeutic goal should be to enhance intestinal adaption and enteral nutrient assimilation, and thereby reduce parenteral nutrition requirements. The induction of hyperphagia is critical. Enteral intake also can be enhanced through enteric tube feeding. There are, however, insufficient data to recommend the universal use of a peptide-based formula (versus a polymeric formula), although the use of such a formula may be considered in individual patients in whom the clinician has compared nutritional outcome with the two types of formulas.

The effect of high-dose enteral glutamine on the incidence and severity of mucositis in paediatric oncology patients

BACKGROUND/OBJECTIVE

The study was conducted to determine if enteral glutamine, 0.65 g kg(-1) daily for 7 days, is effective in reducing the incidence and severity of mucositis in paediatric oncology patients when given alongside chemotherapy. The study was carried out at St James's University Hospital, Leeds, UK.

SUBJECTS/METHODS

This was a randomized study using the patients as their own controls. Seventy-six patients undergoing treatment for paediatric malignancy having at least two identical courses of chemotherapy and at risk of developing mucositis participated in the study. Patients received one course of chemotherapy with glutamine and an identical course without. Alternate patients were allocated to have glutamine with course 1 or with course 2. The severity of symptoms of mucositis and the duration of enteral and parenteral nutrition were recorded. Daily ammonia levels were measured.

RESULTS

Fifty patients completed the study. No statistical significance with regard to symptoms of mucositis was found. Fewer children receiving glutamine required parenteral nutrition (P=0.049), and the duration of parenteral nutrition was less (P=0.023). No adverse effects attributed to taking the glutamine were observed.

CONCLUSIONS

The study showed that high-dose enteral glutamine did not reduce the incidence and severity of oral mucositis as determined by subjective toxicity measurements, but did show a significant reduction in parenteral nutrition usage. No adverse cumulative effect of this oral glutamine dose was observed.

Complications of parenteral nutrition

Parenteral nutrition plays a vital role for patients with intestinal failure and those who are unable to maintain oral or enteral nutrition alone. Parenteral nutrition has been shown to improve clinical outcome in patients with malnutrition and intestinal tract dysfunction. The use of parenteral nutrition is not without risk of serious complications. Parenteral nutrition complications can be divided into mechanical related to vascular access, septic, and metabolic. This article provides a review on the short- and long-term complications of parenteral nutrition and their management.

Gastrointestinal development and meeting the nutritional needs of premature infants

The fear of necrotizing enterocolitis and feeding intolerance are major factors inhibiting the use of the enteral route as the primary means of nourishing premature infants. Parenteral nutrition may help to meet many of the nutritional needs of these infants, but has significant detrimental side effects that include intestinal atrophy, sepsis, and increased susceptibility to inflammatory stimuli and systemic inflammatory responses. Being able to minimize the use of the parenteral route and still maintain appropriate nutrition safely would be a major advance in neonatology. At the basis of our inability to use the enteral route is a poorly understood immature gastrointestinal tract. Approaches such as minimal enteral nutrition or trophic feedings may partially alleviate these problems. However, if we are to progress in greater utilization of the gastrointestinal tract, other factors need to be considered. These include the macronutrient composition of minimal enteral or trophic feedings and the microecology of the intestinal lumen. Some of the developmental aspects of the intestine, which include intestinal growth, motor activity, barrier and other innate immune functions, and the microecology of the developing intestine, are briefly reviewed here. The purpose of this review is to suggest important areas of future research in neonatal and developmental gastroenterology that could affect several conditions that are related to immaturity of the gastrointestinal tract.