Glutamine and the preservation of gut integrity

Parenteral glutamine dipeptide improves nitrogen balance in postoperative patients on total parenteral nutrition (TPM). Animal studies show that the structure and function of the gut is preserved by glutamine. It is not known if this is the case in human beings. 20 patients admitted to hospital for total parenteral nutrition were randomly allocated to receive parenteral nutrition enriched with glycyl-L-glutamine (Gln TPN), or standard parenteral nutrition (STPN). Mucosal biopsy specimens were taken from the second part of the duodenum before starting parenteral nutrition, and after two weeks. The ratio between the urine concentrations of lactulose and mannitol after enteral administration was used to measure intestinal permeability. After two weeks of parenteral nutrition in the GlnTPN group, intestinal permeability was unchanged, whereas permeability in the STPN group increased. Villus height was unaltered in the GlnTPN group but in the STPN group it decreased. The addition of glutamine to parenteral nutrition prevents deterioration of gut permeability and preserves mucosal structure.

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

BACKGROUND

Numerous animal studies have demonstrated intestinal villus atrophy occurs when luminal nutrition is withheld and total parenteral nutrition (TPN) is provided. Intestinal morphologic and functional changes have not been well studied in humans during TPN.

METHODS

Eight normal volunteers were hospitalized in the Clinical Research Center for 3 weeks. The subjects received TPN as an exclusive means of nutritional support for 14 days followed by 5 days of enteral refeeding with either a standard or a glutamine and arginine-supplemented formula. Endoscopic jejunal biopsies were taken before and after TPN and after enteral refeeding. Intestinal morphology was examined by light and transmission electron microscopy. Mucosa DNA, RNA, and protein concentrations were measured. Lactose breath hydrogen and intestinal permeability testing (urinary lactulose and mannitol excretion after an oral dose) were performed before and after TPN and after enteral refeeding.

RESULTS

Total mucosal thickness decreased after TPN (645 +/- 19 to 512 +/_ 19 microns, p = .003) and increased significantly towards baseline after enteral refeeding (575 +/- 19 microns, p = .04). The change was related solely to villus height; crypt depth was unaffected. Villus cell count decreased from 179 +/- 15 to 163 +/- 12 after TPN (p = .03) and increased after enteral refeeding to 176 +/- 21 (p = .06). Crypt cell count was unaffected by TPN or refeeding. A nonsignificant decrease in the mitotic index after TPN was seen. Intracellular edema developed during TPN and resolved with enteral refeeding. The urinary lactulose-mannitol ratio increased with TPN [0.06 +/- 0.03 to 0.11 +/- 0.05 after TPN and 0.14 +/_ 0.09 after short-term enteral refeeding (p = .05)], indicating increased intestinal permeability. The urinary lactulose-mannitol ratio was significantly greater after refeeding with standard formula than the free amino acid peptide formula with glutamine and arginine (0.20 +/- 0.05, vs 0.08 +/- 0.01, p = .05). No significant differences were noted in mucosal RNA, DNA, protein, DNA-protein or RNA-DNA rations or breath hydrogen after lactose ingestion after either TPN or enteral refeeding. No significant difference in plasma glutamine was found during TPN (462.7 +/ 38.7 vs 491.8 +/- 46.1 mumol/L) or after enteral refeeding (457.3 +/- 51.4 mumol/L).

CONCLUSIONS

Intestinal morphologic and functional changes occur in human for whom TPN is the sole nutritional source, although the findings in humans are substantially less significant than observed in animal models. The loss of mucosal structure may be sufficient to cause increased intestinal permeability, the clinical significance of which remains to be defined. Enteral nutrition is important in restoring and probably preventing morphologic intestinal changes associated with TPN, and a peptide and free amino acid-based formula supplemented with glutamine and arginine may have some added role. Our findings also suggest sepsis is associated with gut adaptation rather than degradation.

Increased intestinal permeability is associated with the development of multiple organ dysfunction syndrome in critically ill ICU patients

We conducted a prospective, observational cohort study designed to compare intestinal permeability (IP) and development of multiple organ dysfunction syndrome (MODS) in a subset of critically ill patients in an intensive care unit (ICU). All patients with an expected ICU stay of 72 h or more were entered into the study, and IP was determined on a daily basis whenever possible from the urinary fractional excretion of orally administered lactulose and mannitol (LMR). Forty-seven consecutive patients were studied, and 28 developed MODS either at the time of admission or during their ICU course. These patients, as a group, had significantly worse IP at admission than did a non-MODS cohort (LnLMR: -2.10 +/- 1.10 versus -3.26 +/- 0.83). Those patients who developed MODS following admission also had a significantly greater admission IP than did the non-MODS group (-2.51 +/- 0.85). Differences in IP between cohorts could not be explained by differences in the incidence of systemic inflammatory response syndrome (SIRS)/sepsis or shock. With multivariate regression analysis, the only parameter present on admission that was predictive of subsequent MODS was IP. Differences in IP and the severity of organ dysfunction were also present (MODS severity mild: -3.01 +/- 0.72; moderate: -1.97 +/- 0.69; and severe: -1.12 +/- 0.96). Patients who developed MODS had a persistently abnormal IP during their ICU stay, and a significantly delayed improvement in their IP compared with the non-MODS cohort. We conclude that the development of MODS is associated with an abnormal and severe derangement of IP that is detectable prior to the onset of the syndrome. This observation lends credence to the premise that gastrointestinal (GI) dysfunction may be causally associated with the development of MODS in the critically ill patient.

A single dose of endotoxin increases intestinal permeability in healthy humans

To investigate the effects of endotoxin on gut barrier function, we performed paired studies of intestinal permeability in healthy humans (N = 12) receiving intravenous Escherichia coli endotoxin (4 ng/kg) or 0.9% saline solution. Two nonmetabolizable sugars, lactulose and mannitol, which are standard permeability markers, were administered orally, 30 minutes before and 120 minutes after the test injection. The 12-hour urinary excretion of these substances after endotoxin/saline solution administration was used to quantitate intestinal permeability. After endotoxin administration systemic absorption and excretion of lactulose increased almost two-fold (mean +/- SEM, 263 +/- 36 mumol per 12 hours vs 145 +/- 19 mumol per 12 hours during saline studies). Similar but less marked alterations in mannitol absorption and excretion occurred after endotoxin injection (5.7 +/- 0.3 mmol per 12 hours vs 4.9 +/- 0.3 mmol per 12 hours). When individual 12-hour lactulose excretion after endotoxin administration was related to the magnitude of systemic responses, a significant relationship occurred between lactulose excretion and elaboration of norepinephrine and between lactulose excretion and minimum white blood cell count. These data suggest that a brief exposure to circulating endotoxin increases the permeability of the normal gut. These observations are consistent with the hypothesis that during critical illness, prolonged or repeated exposure to systemic endotoxins or associated cytokines may significantly compromise the integrity of the gastrointestinal mucosal barrier.

Abnormal intestinal permeability to sugars in villous atrophy

Intestinal permeability to a monosaccharide and a disaccharide was compared by simultaneous measurement of the urinary excretion of L-rhamnose and lactulose after oral ingestion of an hypertonic solution containing both sugars. Urine samples were analysed for sugar content by quantitative thin-layer or paper chromatography. Results in thirteen patients with untreated villous atrophy were compared with those in twelve healthy volunteers. Urinary L-rhamnose excretion was significantly decreased (-40%, p less than 0.02) in patients with villous atrophy, whereas lactulose excretion was paradoxically and significantly increased (+345%, p less than 0.01). The median value of the lactulose/L-rhamnose urinary excretion ratio was sevenfold higher in the patients with villous atrophy; there was no overlap of values for patients and volunteers (p less than 0.01). It is postulated that reduced L-rhamnose urinary excretion in untreated villous atrophy is due to a decreased absorptive area in the small bowel, whereas increased lactulose excretion indicates leakiness of the abnormal mucosa to larger polar molecules.

Increased intestinal permeability associated with infection in burn patients

Thermal injury may be associated with disruption of normal gut barrier integrity. To test this hypothesis, we assessed intestinal permeability with the nonmetabolizable, poorly absorbed disaccharide lactulose, which is efficiently excluded by the normal intestinal mucosa. Permeability studies were performed in 15 burned patients (aged 18 to 67 years; mean burn size, 40%) and 11 healthy controls. Lactulose, 10 g, was administered enterally, together with 5 g of mannitol as a control, and urinary excretion rates were determined. Lactulose excretion and the lactulose/mannitol excretion ratio increased threefold (160 +/- 30 vs 57 +/- 7 mumol and 0.113 +/- 0.033 vs 0.035 +/- 0.005) in the infected patients (sepsis score, 10 +/- 2; burn size, 38% +/- 6%). In contrast, noninfected burn patients (sepsis score, 0) had permeability values similar to those of controls (66 +/- 10 mumol and 0.036 +/- 0.007). Permeability increased as the severity of infection increased. Infection in burn patients is associated with increased bowel permeability. The intestine may be a primary source of sepsis. Alternatively, the systemic response to infection may alter gut barrier function, which could facilitate translocation of bacteria and absorption of endotoxin.

Clustering of increased small intestinal permeability in families with Crohn's disease

BACKGROUND & AIMS

Small intestinal permeability is increased in a proportion of patients with Crohn's disease (CD) and a subset of their healthy relatives. A primary permeability defect was postulated in the pathogenesis of the disease. The aim of this study was to identify a possible genetic pattern in the distribution of CD and/or abnormal permeability.

METHODS

Differential urinary excretion of lactulose and mannitol (L/ M) in complete CD families was determined. Controls included healthy families and families with ulcerative colitis. Pedigrees were used to compare the distribution of CD and/or increased permeability.

RESULTS

The L/M was significantly increased in patients with CD. Seventeen of 67 first-degree relatives (25%) had a ratio greater than the upper limit (P95 = 0.0170). Permeability results of CD families showed a highly significant familial aggregation. The lack of a genetic pattern in relation with CD and occurrence of disturbed permeability especially within generation, points toward a shared environmental factor. Five of 14 healthy spouses (36%) of patients with CD had also an increased permeability, and prevalence of increased permeability was not higher in families with known familial occurrence (P = 0.85).

CONCLUSIONS

This large family study confirms an increased permeability in a subset of healthy relatives of patients with CD. However, the absence of a typical family pattern and the high prevalence in spouses is in favor of a common nongenetic factor or a subclinical disease manifestation.

Intestinal permeability in the newborn

Passive intestinal permeability in 33 newborn babies was studied using feeds containing lactulose and mannitol. Each marker is thought to pass across the gut wall by a different route; lactulose by a paracellular and mannitol by a transcellular pathway. Neither is metabolised and both are wholly and solely excreted by the kidney; urinary recovery is a measure of the intestinal uptake. Babies born before 34 weeks' gestation exhibited a higher intestinal permeability to lactulose than more mature babies, and all preterm babies showed an appreciable decline in lactulose absorption during the first week of oral feeds. Babies of 34 to 37 weeks' gestation achieved a 'mature' intestinal permeability to lactulose within four days of starting oral feeds. These findings may reflect the immaturity of the gut of the preterm baby rather than a process essential to adaptation to enteral nutrition.

Intestinal permeability changes during the first month: effect of natural versus artificial feeding

The aim of the study was to investigate the effect of age and feeding pattern on intestinal permeability during the first month of life. The subjects were 72 full-term, healthy neonates who were (a) exclusively breast-fed (BF group, n = 36) or (b) artificially fed (CM group, n = 36) with either an adapted formula (AF group, n = 17) or a partly hydrolyzed (hypoantigenic) formula (HA group, n = 19). A lactulose/mannitol (lac/man) intestinal permeability test was performed at 1 and 7 days (steady-state method, n = 72), then at 30 days of life (single oral load, n = 47). Urinary lactulose and mannitol were measured by HPLC. The mean lac/man urinary ratio dropped from 1.27 +/- 0.73 (day 1) to 0.34 +/- 0.36 at day 7 and to 0.22 +/- 0.21 at day 30. At 7 days BF infants showed a significantly lower lac/man urinary ratio (0.22 +/- 0.25) than the CM group (0.47 +/- 0.41). The human neonate shows a developmental pattern of sugar intestinal permeability that resembles gut closure observed in other mammals. Intestinal permeability decreases faster in breast-fed babies than in those fed with adapted or HA formulas.

Early feeding, antenatal glucocorticoids, and human milk decrease intestinal permeability in preterm infants

To determine the effects of age, feeding regimen, and antenatal glucocorticoids on intestinal permeability, preterm infants (n = 132) were stratified by gestational age and by diet (mothers' own milk versus preterm formula), and assigned randomly to one of four feeding regimens: early-continuous, early-bolus, standard-continuous, and standard-bolus. At 10, 28, and 50 d of age permeability was determined by measuring the ratio of lactulose/ mannitol in the urine after the two sugars were administered enterally for 30 h. The mean (+/-SE) birth weight and gestational age of the infants were 1044 +/- 13 g and 27 +/- 0.1 wk, respectively. Permeability changed as a function of age (p = 0.003). Early feeding was associated with a reduction in permeability at 10 d of age (p = 0.01). Antenatal steroid administration was associated with decreased permeability at 28 d of age (p = 0.017). The feeding of human milk (versus formula) was associated with decreased permeability at 28 d of age (p = 0.02). Continuous versus bolus feeding did not affect permeability.

Impact of zinc supplementation on intestinal permeability in Bangladeshi children with acute diarrhoea and persistent diarrhoea syndrome

Zinc has been shown to enhance intestinal mucosal repair in patients suffering from acrodermatitis enteropathica; but the impact on mucosal integrity during acute (AD) or persistent (PD) diarrhoea is unknown. One hundred eleven children with AD and 190 with PD aged between 3 and 24 months received, randomly and blind to the investigators, either an elemental zinc supplement of 5 mg/kg body wt/day or placebo in multivitamin syrup for 2 weeks while intestinal permeability and, biochemical and anthropometric markers were serially monitored. The permeability test was administered as an oral dose of 5 g lactulose/l g mannitol in a 20-ml solution followed by a 5-h urine collection. The ratio of the urinary probe sugars was correlated to clinical, biochemical, and microbiological parameters. At presentation, lactulose excretion was increased and mannitol excretion decreased in both AD and PD as compared with age-matched asymptomatic children. The lactulose/mannitol ratio (L/M) was higher in subjects with mucosal invasive pathogens (rotavirus and enteropathogenic Escherichia coli) compared with children excreting Vibrio cholera and enterotoxigenic E. coli. Two-week zinc supplementation significantly reduced lactulose excretion in both AD and PD, whereas the change in mannitol excretion and L/M was similar between study groups in both studies. Changes in lactulose excretion were significantly influenced by zinc supplementation in children with E. coli, Shigella sp., and Campylobacter jejuni stool isolates. The greatest reduction in total lactulose excretion was seen in supplemented children who on presentation were lighter (wt/age less than 80%), thinner (wt/ht less than 85%), and undernourished [middle upper arm circumference (MUAC) less than 12.5 cm] or with hypozincaemia (less than 14 mumol/L).(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal permeability and inflammation in patients on NSAIDs

BACKGROUND

The frequency with which non-steroidal anti-inflammatory drugs (NSAIDs) increase small intestinal permeability and cause inflammation is uncertain.

AIMS

To examine small intestinal permeability and inflammation in a large number of patients on long term NSAIDs.

METHODS

Sixty eight patients receiving six different NSAIDs for over six months underwent combined absorption-permeability tests at three different test dose osmolarities (iso-, hypo-, and hyperosmolar). Two hundred and eighty six patients on 12 different NSAIDs underwent indium-111 white cell faecal excretion studies to assess the prevalence and severity of intestinal inflammation.

RESULTS

The iso- and hyperosmolar tests showed significant malabsorption of 3-0-methyl-D-glucose, D-xylose, and L-rhamnose. Intestinal permeability changes were significantly more pronounced and frequent with the hypo- and hyperosmolar as opposed to the iso-osmolar test. Sequential studies showed that four and nine patients (of 13) developed inflammation after three and six months treatment with NSAIDs, respectively. There was no significant difference (p>0.1) in the prevalence (54-72%) or severity of intestinal inflammation in the 286 patients taking the various NSAIDs apart from those on aspirin and nabumetone, these having no evidence of intestinal inflammation. There was no significant correlation between the inflammatory changes and age, sex, dose of NSAID, length of disease, or NSAID ingestion.

CONCLUSIONS

Intestinal permeability test dose composition is an important factor when assessing the effects of NSAIDs on intestinal integrity. All the conventional NSAIDs studied were equally associated with small intestinal inflammation apart from aspirin and nabumetone which seem to spare the small bowel.

Intestinal permeability in patients with coeliac disease and relatives of patients with coeliac disease

The functional integrity of the small bowel is impaired in coeliac disease. Intestinal permeability, as measured by the sugar absorption test probably reflects this phenomenon. In the sugar absorption test a solution of lactulose and mannitol was given to the fasting patient and the lactulose/mannitol ratio measured in urine collected over a period of five hours. The sugar absorption test was performed in nine patients with coeliac disease with an abnormal jejunum on histological examination, 10 relatives of patients with coeliac disease with aspecific symptoms but no villous atrophy, six patients with aspecific gastrointestinal symptoms but no villous atrophy, and 22 healthy controls to determine whether functional integrity is different in these groups. The lactulose/mannitol ratio (mean (SEM) is significantly higher in both coeliac disease (0.243 (0.034), p < 0.0001)) and relatives of patients with coeliac disease (0.158 (0.040), p < 0.005)) v both healthy controls (0.043 (0.006)) and patients with aspecific gastrointestinal symptoms (0.040 (0.011)). The lactulose/mannitol ratio in relatives of coeliac disease patients was significantly lower than in the coeliac disease patient group (p = 0.04). The lactulose/mannitol ratio was the same in healthy controls and patients with aspecific gastrointestinal symptoms. It is concluded that the sugar absorption test is a sensitive test that distinguishes between patients with coeliac disease and healthy controls. The explanation for the increased permeability in relatives of patients with coeliac disease is uncertain. Increased intestinal permeability may be related to constitutional factors in people susceptible to coeliac disease and may detect latent coeliac disease. The sugar absorption test may therefore be helpful in family studies of coeliac disease.

Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis

A randomized, controlled clinical trial investigated the effect of early enteral nutrition (EN) on intestinal permeability, intestinal protein loss, and outcome in parvoviral enteritis. Dogs were randomized into 2 groups: 15 dogs received no food until vomiting had ceased for 12 hours (mean 50 hours after admission; NPO group), and 15 dogs received early EN by nasoesophageal tube from 12 hours after admission (EEN group). All other treatments were identical. Intestinal permeability was assessed by 6‐hour urinary lactulose (L) and rhamnose (R) recoveries (%L, %R) and L/R recovery ratios. Intestinal protein loss was quantified by fecal α₁‐proteinase inhibitor concentrations (α₁‐PI). Median time to normalization of demeanor, appetite, vomiting, and diarrhea was 1 day shorter for the EEN group for each variable. Body weight increased insignificantly from admission in the NPO group (day 3: 2.5±2.8% day 6: 4.3±2.3% mean ± SE), whereas the EEN group exhibited significant weight gain (day 3: 8.1±2.7% day 6: 9.7 ± 2.1%). Mean urinary %L was increased, %R reduced, and L/R recovery ratios increased compared to reference values throughout the study for both groups. Percent lactulose recovery decreased in the EEN group (admission: 22.6±8.0% day 6: 17.9 ± 2.3%) and increased in the NPO group (admission: 11.0±2.6% day 6: 22.5 ± 4.6%, P= .035). Fecal α₁‐PI was above reference values in both groups and declined progressively. No significant differences occurred for %R, L/R ratios, or α₁‐PI between groups. Thirteen NPO dogs and all EEN dogs survived (P= .48). The EEN group showed earlier clinical improvement and significant weight gain. The significantly decreased %L in the EEN versus NPO group might reflect improved gut barrier function, which could limit bacterial or endotoxin translocation.

Cardiopulmonary bypass impairs small intestinal transport and increases gut permeability

Gastrointestinal damage occurs in 0.6% to 2% of patients after cardiopulmonary bypass (CPB), and carries a mortality of 12% to 67%. The incidence of subclinical gastrointestinal damage may be much greater. We examined the effects of nonpulsatile, hypothermic CPB on intestinal absorption and permeability in 41 patients. Bowel mucosal saccharide transport and permeation were evaluated using 100 mL of an oral solution containing 3-O-methyl-D-glucose (0.2 g), D-xylose (0.5 g), L-rhamnose (1.0 g), and lactulose (5.0 g) to assess active carrier-mediated, passive carrier-mediated, transcellular, and paracellular transport, respectively, with a 5-hour urine analysis. Patients were studied before, immediately after, and 5 days after CPB. Immediately after CPB there was a decrease in urinary excretion of 3-O-methyl-D-glucose (from 34% +/- 2.2% to 5.2% +/- 0.7%; p < 0.0001), D-xylose (from 25.4% +/- 1.4% to 4.1% +/- 0.8%; p < 0.0001), and L-rhamnose (from 8.3% +/- 0.6% to 2.6% +/- 0.4%; p < 0.0001). The permeation of 3-O-methyl-D-glucose and D-xylose returned to normal levels 5 days after CPB, but that of L-rhamnose remained significantly below pre-CPB values at 6.6% +/- 0.5% (p = 0.004). However, the permeation of lactulose increased after CPB (from 0.35% +/- 0.04% to 0.59% +/- 0.1%; p = 0.018), and the lactulose/L-rhamnose gut permeability ratio increased markedly (from 0.045 +/- 0.04 to 0.36 +/- 0.08; normal = 0.06 to 0.08; p = 0.004). Patients who had a CPB time of 100 minutes or more had a greater increase in gut permeability (p = 0.049).(ABSTRACT TRUNCATED AT 250 WORDS)

Urine sugars for in vivo gut permeability: validation and comparisons in irritable bowel syndrome-diarrhea and controls

Mucosal barrier dysfunction contributes to gastrointestinal diseases. Our aims were to validate urine sugar excretion as an in vivo test of small bowel (SB) and colonic permeability and to compare permeability in patients with irritable bowel syndrome-diarrhea (IBS-D) to positive and negative controls. Oral lactulose (L) and mannitol (M) were administered with (99m)Tc-oral solution, (111)In-oral delayed-release capsule, or directly into the ascending colon (only in healthy controls). We compared L and M excretion in urine collections at specific times in 12 patients with IBS-D, 12 healthy controls, and 10 patients with inactive or treated ulcerative or microscopic colitis (UC/MC). Sugars were measured by high-performance liquid chromatography-tandem mass spectrometry. Primary endpoints were cumulative 0-2-h, 2-8-h, and 8-24-h urinary sugars. Radioisotopes in the colon at 2 h and 8 h were measured by scintigraphy. Kruskal-Wallis and Wilcoxon tests were used to assess the overall and pairwise associations, respectively, between group and urinary sugars. The liquid in the colon at 2 h and 8 h was as follows: health, 62 ± 9% and 89 ± 3%; IBS-D, 56 ± 11% and 90 ± 3%; and UC/MC, 35 ± 8% and 78 ± 6%, respectively. Liquid formulation was associated with higher M excretion compared with capsule formulation at 0-2 h (health P = 0.049; IBS-D P < 0.001) but not during 8-24 h. UC/MC was associated with increased urine L and M excretion compared with health (but not to IBS-D) at 8-24 h, not at 0-2 h. There were significant differences between IBS-D and health in urine M excretion at 0-2 h and 2-8 h and L excretion at 8-24 h. Urine sugars at 0-2 h and 8-24 h reflect SB and colonic permeability, respectively. IBS-D is associated with increased SB and colonic mucosal permeability.

Early feeding, feeding tolerance, and lactase activity in preterm infants

OBJECTIVE

We sought to ascertain whether the timing of feeding initiation affected the development of intestinal lactase activity and whether there are clinical ramifications of lower lactase activity.

STUDY DESIGN

Preterm infants (26 to 30 weeks' gestation; n = 135) were randomly assigned to begin enteral feedings at either 4 (early group) or 15 days of age (standard group). At 10, 28, and 50 days of age lactase activity was determined by measuring the urinary ratio of lactulose/lactose after the 2 sugars were administered.

RESULTS

Lactase activity increased significantly over time. Infants in the early group had greater lactase activity at 10 days of age (by 100%) and 28 days of age (by 60%) than the standard group. At 10 days of age lactase activity was greater in milk- versus formula-fed infants. The time required to achieve full enteral feedings, the number of abnormal abdominal x-ray examinations, and the total number of abdominal x-ray examinations were inversely related to lactase activity.

CONCLUSIONS

Early feeding increases intestinal lactase activity in preterm infants. Lactase activity is a marker of intestinal maturity and may influence clinical outcomes. Whether the effects of milk on lactase activity were due to the greater concentration of lactose in human milk compared with that in formula must be determined.

Intestinal permeability changes in response to acetylsalicylic acid in relatives of patients with Crohn's disease

BACKGROUND & AIMS

Presence of a familial intestinal permeability defect in Crohn's disease remains controversial despite numerous studies. The purpose of this study was to determine whether detection of a permeability defect in first-degree relatives of patients with Crohn's disease can be enhanced using an acetylsalicylic acid provocation test.

METHODS

Lactulose-mannitol ratio, a measure of intestinal permeability, and total sucrose excretion, a measure of gastroduodenal permeability, were determined before and after ingestion of acetylsalicylic acid in healthy controls, in patients with Crohn's disease, and in the first-degree relatives of patients with Crohn's disease. Subjects were classified as hyperresponders if their results were above the mean of + 2SD of the controls.

RESULTS

First-degree relatives had a 110% increase in intestinal permeability after acetylsalicylic acid compared with an increase of 57% in controls (P = 0.001). Thirty-five percent of relatives were classified as hyperresponders. There was no significant difference in the change in sucrose excretion between relatives and controls (259% vs 198%; P < 0.05).

CONCLUSIONS

First-degree relatives of patients with Crohn's disease have an exaggerated increase in intestinal but not gastroduodenal permeability in response to acetylsalicylic acid. This study supports a familial permeability defect in Crohn's disease, which may not be present in all families.

Gut mucosal atrophy after a short enteral fasting period in critically ill patients

PURPOSE

The purpose of this study was to evaluate the presence of gut mucosal atrophy and changes in mucosal permeability in critically ill patients after a short fasting period.

MATERIALS AND METHODS

Fifteen critically ill patients underwent a period of enteral fasting of at least 4 days (mean 7.8 days). We took the following measurements the day before initiating enteral nutrition: indirect calorimetry, serum albumin, prealbumin, and lymphocyte count. We also performed a duodenal endoscopic biopsy with histopathological and mucosal morphometric analysis including villus height and crypt depth. The lactulose-mannitol test was performed to assess gut permeability. A total of 28 healthy volunteers served as controls for duodenal biopsy or lactulose-mannitol test. Clinical data, such as length of fasting, severity score, and previous parenteral nutritional support, were recorded.

RESULTS

We found gut mucosal atrophy, expressed as a decrease in villus height and crypt depth, in patients compared with controls. The patients also exhibited an abnormal lactulose-mannitol test. Morphometric changes did not correlate with permeability. Further, we found no correlation between the results of the lactulose-mannitol test and of mucosal morphometry with clinical data.

CONCLUSIONS

We found that a short period of enteral fasting was associated with significant duodenal mucosal atrophy and abnormal gut permeability in critically ill patients.

Intestinal permeability in liver cirrhosis: relationship with severe septic complications

OBJECTIVES

Patients with liver cirrhosis are at high risk of severe septic complications such as spontaneous bacterial peritonitis (SBP) and bacteraemia. The aims of this study were to assess intestinal permeability in patients with liver cirrhosis and to search for a relationship between an impaired intestinal permeability and the occurrence of severe septic complications.

METHODS

Intestinal permeability was assessed in a group of 80 cirrhotic patients (Child A, n = 13; Child B, n = 26; Child C, n = 41) and 28 healthy control subjects. A severe septic complication (bacteraemia and/or SBP) occurred in 16 patients, within 10 days before (n = 8 cases) or after (n = 8 cases) the test was performed. Lactulose (LAC) 10 g was given orally together with mannitol (MAN) 5 g, and urinary excretion rates were determined.

RESULTS

Urinary mannitol excretion (MAN%) was lower while the LAC/MAN ratio was higher in patients than in control subjects (P < 0.001); these abnormalities were more marked in Child C patients (Child C patients vs control subjects: MAN%, 8.20 +/- 0.79 vs 14.59 +/- 0.58, P < 0.001; LAC/MAN, 0.066 +/- 0.026 vs 0.017 +/- 0.001, P < 0.02). When compared with non-infected patients, septic patients had a lower MAN% and an increased LAC/ MAN ratio (5.45 +/- 1.12 vs 9.83 +/- 0.87, P < 0.02; 0.130 +/- 0.063 vs 0.029 +/- 0.005, P < 0.02).

CONCLUSION

Although the main mechanism involved in the decrease in MAN% is likely a reduction in area of the intestinal absorptive surface, these results argue in favour of an increased intestinal permeability in liver cirrhosis, especially in patients with severe infectious complications. The impairment of intestinal function barrier may contribute to severe septic complications in these patients.

Intestinal absorption of the intact peptide carnosine in man, and comparison with intestinal permeability to lactulose

1. Healthy humans ingested the dipeptide carnosine (L-beta-alanyl-L-histidine). Their plasma levels and urinary outputs of carnosine and beta-alanine were monitored over the following 5 h. 2. Large amounts of intact carnosine (up to 14% of the ingested dose) were recovered in the urine over the 5 h after ingestion. However, carnosine was undetectable in the plasma unless precautions were taken to inhibit blood carnosinase activity ex vivo during and after blood collection. 3. The amount of carnosine recovered in urine varied substantially between subjects. It correlated negatively with carnosinase enzymic activity in the plasma. Highest carnosinase activities were observed in those subjects who regularly underwent physical training. 4. Urinary recovery of the disaccharide lactulose also varied considerably between subjects, but was substantially lower than that of carnosine. There was no significant correlation between the recoveries of carnosine and lactulose. 5. When lactulose was ingested with a hypertonic solution, the urinary recovery of lactulose was generally increased. When carnosine was ingested with a hypertonic solution, the urinary recovery of carnosine was reduced: hence the paracellular route probably is not dominant for absorption of intact carnosine. 6. Intact carnosine must have crossed the intestine to an extent much greater than hitherto recognized. Rapid post-absorptive hydrolysis is a severe obstacle to quantification of intact peptide absorption.

Intestinal permeability in patients with adverse reactions to food

BACKGROUND

An abnormal intestinal permeability could contribute to establish an altered sensitivity to food-allergen.

AIM

To evaluate the intestinal permeability in subjects with adverse reactions to food on allergen-free diet.

SUBJECTS

Twenty-one patients with food allergy and 20 with food hypersensitivity on allergen-free diet were enrolled and divided in four groups according to the seriousness of their referred clinical symptoms when they were on a free diet.

METHODS

Intestinal permeability was evaluated by Lactulose/Mannitol ratio urinary detection determined by anion-exchange chromatography.

RESULTS

Statistically significant different Lactulose/Mannitol ratio was evidenced in subjects with food allergy (p=0.003) or hypersensitivity (p=0.0008) compared to control patients. The correlation between Lactulose/Mannitol ratio and the seriousness of clinical symptoms, by using Spearman test, was statistically significant for food allergy (p=0.0195) and hypersensitivity (p=0.005) patients.

CONCLUSIONS

The present data demonstrate that impaired intestinal permeability, measured in our conditions, is present in all subjects with adverse reactions to food. In addition, for the first time, we report a statistically significant association between the severity of referred clinical symptoms and the increasing of Intestinal Permeability Index. These data reveal that intestinal permeability is not strictly dependent on IgE-mediated processes but could better be related to other mechanisms involved in early food sensitisation, as breast-feeding, or microbial environment that influence the development of oral tolerance in early infancy.

Effects of enteral supplementation with glutamine granules on intestinal mucosal barrier function in severe burned patients

Glutamine is an important energy source in intestinal mucosa, the small intestine is the major organ of glutamine uptake and metabolism and plays an important role in the maintenance of whole body glutamine homeostasis. The purpose of this clinical study is to observe the protection effects of enteral supplement with glutamine granules on intestinal mucosal barrier function in severe burned patients. Forty-eight severe burn patients (total burn surface area 30-75%, full thickness burn area 20-85%) were randomly divided into two groups: burn control group (B group, 23 patients) and glutamine treated group (Gln group, 25 patients). Glutamine granules 0.5 g/kg were supplied orally for 14 days in Gln group, and the same dosage of placebo were given for 14 days in B group. The plasma level of glutamine, endotoxin and the activity of diamine oxidase (DAO), as well as intestinal mucosal permeability were determined. The results showed that the levels of plasma endotoxin, activity and urinary lactulose and mannitol (L/M) ratio in all patients were significant higher than that of normal control. After taking glutamine granules for 14 days, plasma glutamine concentration was significantly higher in Gln group than that in B group (607.86+/-147.25 microM/l versus 447.63 +/- 132.28 microM/l, P < 0.01). On the other hand, the levels of plasma DAO activity and urinary L/M ratio in Gln group were lower than those in B group. In addition, the wound healing was better and hospital stay days were reduced in the Gln group (46.59 +/- 12.98 days versus 55.68 +/- 17.36 days, P < 0.05). These results indicated that glutamine granules taken orally could abate the degree of intestine injury, lessen intestinal mucosal permeability, ameliorate wound healing and reduce hospital stay.

Intestinal barrier dysfunction in clinical and experimental obstructive jaundice and its reversal by internal biliary drainage

Intestinal mucosal barrier function in obstructive jaundice was assessed in an animal model and in patients. The effect of internal biliary drainage in patients was also examined. Bile duct ligation for 1 week in the rat resulted in significant bacterial translocation (in seven of 12 animals following ligation versus none of the shamoperated controls, P < 0.01). Intestinal permeability, measured by the urinary recovery of orally administered polyethylene glycol, was also significantly increased (+66.2 per cent for ligation versus -11.6 per cent for sham, P < 0.01). A prospective study was performed on 33 patients with obstructive jaundice undergoing internal biliary drainage, and results were compared with those in six non-jaundiced patients undergoing laparotomy or endoscopic retrograde cholangiopancreatography and in 11 health volunteers. The lactulose: mannitol ratio was used as an intestinal permeability index. Mean(s.e.m.) intestinal permeability assessed before operation was significantly increased in jaundiced patients compared with control patients (0.050(0.010) versus 0.016(0.003), P < 0.005). The mean(s.e.m.) lactulose: mannitol ratio in the healthy volunteers was 0.020(0.003), which was similar to that in control patients. In the jaundiced group of patients the intestinal permeability index fell to within normal levels after 28 days of internal biliary drainage (0.050 before operation versus 0.021 at 28 days, P < 0.02). These data indicate that intestinal barrier function is impaired in obstructive jaundice and that this impairment is reversed by return of bile to the gastrointestinal tract.

Increased gut permeability after multiple trauma

Gut permeability was studied in multiply injured patients with respect to the development of multiple organ failure (MOF). Two groups were defined according to MOF score (threshold 10 points) as to whether MOF developed (group 1; n = 11, four deaths) or did not (group 2; n = 21, no death). Gut permeability was determined from the ratio of urinary excretion of enterally administered lactulose and mannitol. Serum elastase concentrations were also determined. Mean(s.e.m.) gut permeability was abnormal during the entire study (day 1: group 1--5.1(2.1) versus group 2--10.6(4.1) (P not significant; P < 0.001 versus normal volunteers, 0.56(0.24)). An increase on days 3 and 5 correlated with serum elastase levels only in patients in group 1 (rs = 0.71, P < 0.01). Severe injury leads to increased intestinal permeability, which is related to a systemic inflammatory response.