Novel substrates to maintain gut integrity

Antibiotics Effects on the Fecal Metabolome in Preterm Infants

Within a randomized prospective pilot study of preterm infants born at less than 33 weeks' gestation, weekly fecal samples from 19 infants were collected and metabolomic analysis was performed. The objective was to evaluate for differences in fecal metabolites in infants exposed to antibiotics vs. not exposed to antibiotics in the first 48 h after birth. Metabolomics analysis was performed on 123 stool samples. Significant differences were seen in the antibiotics vs. no antibiotics groups, including pathways related to vitamin biosynthesis, bile acids, amino acid metabolism, and neurotransmitters. Early antibiotic exposure in preterm infants may alter metabolites in the intestinal tract of preterm infants. Broader multi-omic studies that address mechanisms will guide more prudent antibiotic use in this population.

[Recent Advances in Management of Acute Pancreatitis]

Acute pancreatitis is common but remains a condition with significant morbidity and mortality. Despite a better understanding of the pathophysiology of acute pancreatitis achieved during the past few decades, there is no specific pharmacologic entity available. Therefore, supportive care is still the mainstay of treatment. Recently, novel interventions for increasing survival and minimizing morbidity have been investigated, which are highlighted in this review.

Changes in bacterial population of gastrointestinal tract of weaned pigs fed with different additives

This study aimed to provide novel insights into the gastrointestinal microbial diversity from different gastrointestinal locations in weaning piglets using PCR-restriction fragment length polymorphism (PCR-RFLP). Additionally, the effect of different feed additives was analyzed. Thirty-two piglets were fed with four different diets: a control group and three enriched diets, with avilamycin, sodium butyrate, and a plant extract mixture. Digesta samples were collected from eight different gastrointestinal segments of each animal and the bacterial population was analysed by a PCR-RFLP technique that uses 16S rDNA gene sequences. Bacterial diversity was assessed by calculating the number of bands and the Shannon-Weaver index. Dendrograms were constructed to estimate the similarity of bacterial populations. A higher bacterial diversity was detected in large intestine compared to small intestine. Among diets, the most relevant microbial diversity differences were found between sodium butyrate and plant extract mixture. Proximal jejunum, ileum, and proximal colon were identified as those segments that could be representative of microbial diversity in pig gut. Results indicate that PCR-RFLP technique allowed detecting modifications on the gastrointestinal microbial ecology in pigs fed with different additives, such as increased biodiversity by sodium butyrate in feed.

Parenteral nutrition versus enteral nutrition in severe acute pancreatitis

PURPOSE

To compare the effect of parenteral versus enteral nutritional support in severe acute pancreatitis, with respect to efficacy, safety, morbidity, mortality and length of hospitalization.

METHODS

The study was comprised of 31 patients, divided into a parenteral group (n=16) and an enteral group (n=15), who met severity criteria for abdominal tomography (Balthazar classes C, D, and E). The patients were compared by demographics, disease etiology, antibiotic prophylaxis, use or not of somatostatin, nutritional support, complications and disease progression.

RESULTS

There was no statistical difference in the average duration of nutritional support, somatostatin, or antibiotics in the two groups. Imipenem was the drug of choice for prophylaxis of pancreatic infections in both groups. More complications occurred in the parenteral group, although the difference was not statistically significant (p=0.10). Infectious complications, such as catheter sepsis and infections of the pancreatic tissue, were significantly more frequent in the parenteral group (p=0.006). There was no difference in average length of hospitalization in the two groups. There were three deaths in the parenteral group and none in the enteral group.

CONCLUSION

Enteral nutritional support is associated with fewer septic complications compared to parenteral nutritional support.

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.

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.

Effects of butyrate, avilamycin, and a plant extract combination on the intestinal equilibrium of early-weaned pigs1

We evaluated the effects of 3 additives, sodium butyrate (AC), avilamycin (AB), and a combination of plant extracts (XT), on the productive performance and the intestinal environment of the early-weaned pig. The XT was a standardized mixture with 5% (wt/wt) carvacrol (from Origanum spp.), 3% cinnamaldehyde (from Cinnamonum spp.), and 2% capsicum oleoresin (from Capsicum annum). Pigs (n = 32) weaned at 18 to 22 d of age with an initial BW of 6.0 +/- 0.10 kg were allocated to 8 pens that, in turn, were allocated to 4 treatments. The treatments included a basal diet (CT) or the basal diet supplemented with 0.3% of AC, 0.04% of AB, or 0.03% of XT. Productive performance was determined during the initial 14 d postweaning. On d 19 and 21 of the experiment, the pigs were killed to allow collection of digesta and intestinal tissue to evaluate variables indicative of aspects of the gastrointestinal environment. Treatments AB and AC improved G:F (P = 0.012 and 0.003, respectively) compared with the CT. Butyrate included in the diet was only detected in the stomach but not in cranial jejunum. When compared with CT, AC produced a lower ileal starch digestibility (P = 0.002) and a lower whole-tract OM and starch digestibility (P = 0.001 and 0.003, respectively), related to a lower VFA concentration in the cranial colon (P = 0.082) and a numerically reduced branched VFA percentage in the rectum. The AB treatment diminished propionate production in caudal colon (P = 0.002) and rectum (P = 0.012) compared with CT. The AC group exhibited deeper crypt depth in the jejunum without variations in villus height compared with CT (P = 0.042). The AC and AB groups also increased goblet cell presence in the colon (P = 0.001 and 0.032, respectively). On the other hand, AB and XT diminished intraepithelial lymphocytes in the jejunum (P = 0.003 and 0.034, respectively). The XT increased lymphocyte presence in the colon (P = 0.003). These results show the important influence of AB and AC on productive performance and on pig gut dynamics. The intestinal modifications observed for AB and AC compared with CT suggest distinct modes of action for each additive.

Morphology of the small intestinal mucosal surface of broilers in relation to age, diet formulation, small intestinal microflora and performance

1. Three experiments were performed to relate morphological characteristics of the small intestinal mucosal surface to age, dietary factors, small intenstinal microflora and performance of broilers. Characterisation of the small intestinal mucosal surface using a dissecting microscope was based on the orientation of the villi, villus shape and the presence of convoluted villi. 2. In Trial 1, the morphological changes of the mucosal surface were studied weekly in the period from 7 to 28 d of age. At d 7 mainly tongue- and leaf-shaped villi together with some ridge-shaped ones were observed in the middle section of the small intestine, displaying a regular zigzag pattern on 53% of the mucosal surface. During the period from d 7 to 14, the area with ridge-shaped villi increased from 7 to 63% and did not change significantly over the next 2 weeks. 3. In Trial 2, three protein sources, soy isolate (SI), wheat gluten (WG), hydrolysed wheat gluten (HWG) and SI with added L-glutamine (SI + Gln), were studied with respect to their effect as dietary components on villus morphology in the mid-small intestine and performance. Diets were fed with (0 to 14 d) and without pectin (14 to 21 d). Feed conversion ratio on the HWG diet improved in comparison to the native WG diet. During the period 0 to 14 d of age the mucosal area with zigzag-oriented villi increased when the pectin diet was supplemented with Gln. Moreover, weight gain of birds fed the SI + Gln diet increased in the period 41 to 21 d. 4. In Trial 3, a study was made of the morphological response of the villi to a stimulation of microbial activity in the digesta after addition of highly methylated pectin to the soybean meal (SBM) diet. This was performed with and without inoculation of a non-virulent Salmonella typhimurium on d 7. By d 21 the birds fed the pectin diet showed impaired weight gain and higher feed conversion. The pectin affected the mucosal surface by decreasing the area with the zigzag pattern and increasing the area with convoluted, mainly ridge-shaped villi. The Salmonella typhimurium infection increased the effects of pectin on performance and mucosal morphology.

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 to ensure optimum recovery. Total parenteral nutrition (TPN) has been the standard practice for providing exogenous nutrients to patients with severe acute pancreatitis. However, recent data suggest that enteral nutrition (EN) is feasible. Thus, a comparison of EN and TPN in patients with acute pancreatitis needs to be made.

OBJECTIVES

To compare the effect of total parenteral nutrition (TPN) versus enteral nutrition (EN) on mortality, morbidity and length of hospital stay in patient with acute pancreatitis.

SEARCH STRATEGY

Trials were identified by computerized searches of The Cochrane Controlled Trials Register, MEDLINE, and EMBASE. Additional studies were identified and included where relevant by searching Scisearch, the bibliographies of review articles and identified trials, and personal files. The search was undertaken in August, 2000 and updated in September 2002. No language restrictions were applied.

SELECTION CRITERIA

Randomized clinical trials, in which nutrition support with TPN were compared to EN in patients with acute pancreatitis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently abstracted data and assessed trial quality. Information was collected on death, length of hospital stay, systemic infection, local septic complications, and other local complications.

MAIN RESULTS

Two trials with a total of 70 participants were included. The relative risk (RR) for death with EN vs TPN was 0.56 (95% CI 0.05 to 5.62). Mean length of hospital stay was reduced with EN (WMD -2.20, 95% CI -3.62 to -0.78). RR for systemic infection with EN vs TPN was 0.61 (95% CI 0.29 to 1.28). In one trial, RR for local septic complications and other local complications with EN vs TPN was 0.56 (95% CI 0.12 to 2.68) and 0.16 (95% CI 0.01 to 2.86) respectively.

REVIEWER'S CONCLUSIONS

Although there is a trend towards reductions in the adverse outcomes of acute pancreatitis after administration of EN, clearly there are insufficient data to draw firm conclusions about the effectiveness and safety of EN versus TPN. Further trials are required with sufficient size to account for clinical heterogeneity and to measure all relevant outcomes.

Oral glutamine in paediatric oncology patients: a dose finding study

OBJECTIVE

The purpose of this study was to determine the most appropriate dose of oral glutamine to use in a further clinical study in paediatric oncology patients.

DESIGN

This was a phase I, pharmokinetic study.

SETTING

The study was carried out at The Yorkshire Regional Centre for Paediatric Oncology and Haematology, St James's University Hospital, Leeds, UK.

SUBJECTS

Thirteen patients undergoing treatment for paediatric malignancy participated in this study. All 13 completed the study.

INTERVENTIONS

The most appropriate dose was determined by patient acceptability and by plasma glutamine and ammonia levels measured at timed intervals after ingestion of a single glutamine dose.

RESULTS

Doses of 0.35, 0.5 and 0.65 g/kg were well tolerated with no untoward plasma glutamine and ammonia levels. One patient was recruited to a higher dose of 0.75 g/kg, but the plasma glutamine and ammonia levels peaked at 2601 and 155 micro mol/l, respectively. The ammonia level was greater than the acceptable upper limit. It was difficult to disperse the glutamine adequately at this dose, resulting in the suspension being found to be unpalatable and therefore no further patients were recruited at this dose.

CONCLUSION

It was concluded that 0.65 g/kg is a safe dose of glutamine to use in a clinical study in paediatric oncology patients.

Key nutrients and growth factors for the neonatal gastrointestinal tract

The nutritional support of gastrointestinal growth and function is an important consideration in the clinical care of neonatal infants. In most health infants, the provision of either breast milk or formula seems to support normal intestinal mucosal growth, but the most significant advantages of breast milk may be for host defense or gut barrier-related functions that are involved in reducing infection. The specific effects of various milk-borne growth factors on key mucosal immune and barrier functions are likely to provide valuable new clues to the advantages of human milk. A substantial number of preterm, low-birth weight babies or those suffering from compromised intestinal function, however, often cannot tolerate oral feedings and instead receive TPN. The consequences of TPN on gastrointestinal function and how this contributes to morbidity of these infants warrants further study, with respect to both clinical and basic research questions. Although enteral nutrition seems to be a critical stimulus for intestinal function, the minimal amounts and composition of nutrients necessary to maintain specific intestinal functions remain to be established. The experimental tools exist to start defining the specific nutrient requirements for the infant gut and some of these nutrients are known (e.g., glutamate, glutamine, and threonine). Peptide growth factors and gut hormones clearly play a role in gut growth and in several ways mediate the trophic actions of enteral nutrition. Although a number of these growth factors are good candidates for therapeutic use, their clinical application in the management of gastrointestinal insufficiency and disease has been slow. The emergence of GLP-2 as a trophic peptide that seems to target the gut is a promising candidate on the horizon.

New developments in glutamine delivery

Numerous studies demonstrate that free glutamine can be added to commercially available crystalline amino acid-based preparations before their administration. Instability during heat sterilization and prolonged storage and limited solubility (35 g/L at 20 degrees C) hamper the use of free glutamine in the routine clinical setting. Indeed, there are many well-controlled and valuable trials with free glutamine, yet its use is restricted to clinical research. The obvious limitations of using free glutamine initiated an intensive search for alternative substrates. Synthetic glutamine dipeptides are stable under heat sterilization and highly soluble; these properties qualify the dipeptides as suitable constituents of nutritional preparations. Industrial production of these dipeptides at a reasonable price is an essential prerequisite for implications of dipeptide-containing solutions in clinical practice. Recent development of novel synthesis procedures allows increased capacity in industrial-scale production. Basic studies with synthetic glutamine-containing short-chain peptides provide convincing evidence that these new substrates are cleared rapidly from plasma after parenteral administration, without being accumulated in tissues and with negligible loss in urine. The presence of membrane-bound as well as tissue-free extracellular hydrolase activity facilitates a prompt and quantitative peptide hydrolysis, the liberated amino acids being available for protein synthesis and/or generation of energy. In the clinical setting, glutamine dipeptide nutrition beneficially influences outcome (nitrogen balance, immunity, gut integrity, hospital stay, morbidity and mortality). The provision of conditionally indispensable glutamine should be considered a necessary replacement of a deficiency rather than a supplementation. The beneficial effects observed with glutamine dipeptide nutrition should be seen simply as a correction of disadvantages produced by the inadequacy of conventional clinical nutrition. The availability of stable dipeptide preparations certainly facilitates, for the first time, adequate amino acid nutrition of critically ill, malnourished or stressed patients in the routine clinical setting and, thus, represents a new dimension in artificial nutrition.

The scientific basis of immunonutrition

Substrates with immune-modulating actions have been identified among both macro- and micronutrients. Currently, the modes of action of individual immune-modulating substrates, and their effects on clinical outcomes, are being examined. At present, some enteral formulas are available for the clinical setting which are enriched with selected immune-modulating nutrients. The purpose of the present paper is to review the scientific rationale of enteral immunonutrition. The major aspects considered are mucosal barrier structure and function, cellular defence function and local or systemic inflammatory response. It is notable that in critical illness the mucosal barrier and cellular defence are impaired and a reinforcement with enteral immunonutrition is desirable, while local or systemic inflammatory response should be down regulated by nutritional interventions. The results available from clinical trials are conflicting. Meta-analyses of recent trials show improvements such as reduced risk of infection, fewer days on a ventilator, and reduced length of intensive care unit and hospital stay. Thus, a grade A recommendation was proclaimed for the clinical use of enteral immune-modulating diets. Improvement in outcome was only seen when critical amounts of the immune-modulating formula were tolerated in patients classified as being malnourished. However, in other patients with severe sepsis, shock and organ failure, no benefit or even disadvantages from immunonutrition were reported. In such severe conditions we hypothesize that systemic inflammation might be undesirably intensified by arginine and unsaturated fatty acids, directly affecting cellular defence and inflammatory response. We therefore recommend that in patients suffering from systemic inflammatory response syndrome great caution should be exercised when immune-enhancing substrates are involved which may aggravate systemic inflammation.

Evolution of nutritional support in acute pancreatitis

BACKGROUND

Acute pancreatitis is a catabolic illness and patients with the severe form have high metabolic and nutrient demands. Artificial nutritional support should therefore be a logical component of treatment. This review examines the evidence in favour of initiating nutritional support in these patients and the effects of such support on the course of the disease.

METHODS

Medline and Science Citation Index searches were performed to locate English language publications on nutritional support in acute pancreatitis in the 25 years preceding December 1999. Manual cross-referencing was also carried out. Letters, editorials, older review articles and most case reports were excluded.

RESULTS AND CONCLUSION

There is no evidence that nutritional support in acute pancreatitis affects the underlying disease process, but it may prevent the associated undernutrition and starvation, supporting the patient while the disease continues and until normal and sufficient eating can be resumed. The safety and feasibility of enteral nutrition in acute pancreatitis have been established; enteral nutrition may even be superior to parenteral nutrition. Some patients, however, cannot tolerate enteral feeding and this route may not be practical in others. Parenteral nutrition still has a role, either on its own or in combination with the oral and enteral routes, depending on the stage of the illness and the clinical situation.

A comparison of parenteral and enteral feeding in neonatal piglets, including an assessment of the utilization of a glutamine-rich, pediatric elemental diet

BACKGROUND

The amino acid requirement profile for infants is different than that for adults and needs to be established; this profile also is different for infants receiving total parenteral nutrition. We used the neonatal piglet as a model for the infant to address (1) the metabolic and physiologic changes due to route of feeding and (2) the adequacy of the amino acid pattern in a pediatric elemental diet.

METHODS

Diets differed only in their amino acid pattern (modified human milk [MHM] and a commercial pediatric elemental diet [PED]) and were fed continuously for 8 days. Control piglets were fed MHM diet via gastric catheters (IG) and were compared with pigs fed MHM diet via venous catheters (IV) or to pigs IG-fed PED.

RESULTS

MHM-IV piglets experienced enlarged livers and gut atrophy, and lower nitrogen retention and body protein content. Higher glutamine (and lower glutamate) in PED-IG, compared with MHM-IG, produced no apparent advantage with respect to gut growth or histology. Proline, histidine, and lysine may have been limiting, and isoleucine and valine excessive, in the PED-IG diet as indicated by plasma concentrations, compared with sow-fed piglets; however, imbalances in the amino acid profile were not excessive because nitrogen retention was not different between MHM-IG or PED-IG pigs.

CONCLUSIONS

Therefore, the amino acid profile of MHM needs to be modified to improve nitrogen retention during parenteral feeding and the profile of oral PED could be improved to normalize plasma amino acid concentrations.

Nutritional modulation of gut inflammation

Nutritional therapy is an important component of the management of gastrointestinal inflammation, which disrupts the gut mucosal barrier leading to sepsis, SIRS and MODS. Future studies will be needed to define the role of specific nutrients in enhancing mucosal barrier function and supporting general immune function, and how this affects morbidity and mortality of critically-ill patients.

Disease-associated malnutrition in the year 2000

Malnutrition is associated with increased morbidity and mortality and is common in patients admitted to hospital. Nutritional status is not routinely assessed on admission, and nutritional depletion escapes recognition in the majority of affected patients. Nutritional status declines during hospital stay, and this trend is most marked in patients who are already malnourished on admission. Techniques for nutritional support are available, their appropriate use leads to improved nutritional status and clinical outcome in most patients. There is evidence that the current use of artificial nutrition is suboptimal and associated with a high complication rate. The introduction of clinical guidelines and the formation of nutrition support teams will improve nutritional management in the future. The development of new substrates and 'pharmaconutrition' is likely to further improve the outcome for many patients. There will remain a need for more studies to define the cost efficacy of artificial nutrition across a broad spectrum of clinical practice.