Assessment of intestinal permeability using sugar probes: influence of urinary volume

BACKGROUND

As the accuracy of the "Sugar Test" is currently debated, this study was conducted to focus on how urine volumes may impact the test results.

METHODS

Fifty-five subjects, 23 healthy and 32 with Irritable Bowel Syndrome (IBS), were enrolled. Lactulose and D-mannitol dissolved in water were administered to all the participating subjects; the urine excreted was collected and the total urine volume was measured. The urine samples were analyzed by High Performance Liquid Chromatography (HPLC). The results were expressed as percentage of urine recovery of lactulose and D-mannitol and lactulose/D-mannitol ratio (LMR).

RESULTS

All subjects were divided into two groups: subjects with urine volume < 500 mL and subjects with urine volume > or = 500 mL. Urine analysis showed that the mean LMR was significantly lower in subjects with urine volume > or = 500 mL than in subjects with urine volume < 500 mL (0.02 +/- 0.02 vs 0.04 +/- 0.04; p < 0.05). A significant increase in D-mannitol recovery was found to be associated with greater urine volumes (p < 0.001).

CONCLUSIONS

The urine volume may influence urinary excretion of sugar probes. Intake of liquids should therefore be carefully monitored before and during the test and the volume of urine produced over the period of collection should be precisely measured.

[The change of intestinal mucosa barrier in chronic severe hepatitis B patients and clinical intervention]

OBJECTIVE

To study the change of intestinal mucosa barrier in chronic severe hepatitis B patients and clinical intervention.

METHOD

(1) 30 normal healthy controls and 60 chronic severe hepatitis B patients were enrolled in this study. The change of intestinal permeability was determined by urine lactulose/ mannitol ratio (L/M), and the serum diamine oxidase (DAO) was measured. (2) 60 chronic severe hepatitis B patients were randomly divided into two groups: the control group and the treated group, each group has 30 cases. Patients in the control group received standard treatment for 2 weeks, however, in addition to standard treatment, patients in the treated group also received glutamine 10g tid. Endotoxin (ET), DAO and L/M were compared between the two group.

RESULTS

(1) Compared to healthy controls, the level of L/M and DAO was significantly increased in chronic severe hepatitis B patients (t = 2.762, P less than 0.01 or t = 6.326, P less than 0.01). (2) Compared to the control group, ET, DAO and L/M were significantly lower 2 weeks after treatment (F = 11.662, P less than 0.01; F = 12.699, P less than 0.01; F = 19.981, P less than 0.01).

CONCLUSION

(1) There is an early intestinal mucosa barrier damage in chronic severe hepatitis B patients. (2) Compared to standard treatment, adding glutamine can reverse intestinal mucosa barrier damage.

[A study of urine lactulose/mannitol ratio and intestinal fatty acid binding protein as the indexes of intestinal damage in sepsis]

OBJECTIVE

To assess urine lactulose/mannitol ratio (LMR), and intestinal fatty acid binding protein (IFABP) concentration as the indexes of intestinal damage in septic patients, and to evaluate the clinical severity and mortality of septic patients by use of these indexes.

METHODS

Thirty-eight patients with sepsis were consecutively selected in Beijing Friendship Hospital intensive care unit (ICU) from June 2007 to February 2008, according to the inclusions and exclusions criteria. Urine samples were taken in 72 hours after ICU admission. Urine LMR was determined by high performance liquid chromatography by use of pulsed electrochemical detection (HPLC-PED), and urine IFABP concentration was determined by enzyme-linked immunosorbent assays (ELISA). The results of LMR and IFABP were analyzed with acute physiology and chronic health evaluation II (APACHE II) score, with multiple organ dysfunction syndrome (MODS) or not and outcome on day 28. The relationship between the two indexes and the patients' gastrointestinal function score was analyzed.

RESULTS

Thirty-eight patients included had significantly higher urine level of IFABP concentration and LMR. Urine LMR were higher in patients with APACHE II score > 20 than in patients with APACHE II score < or =20 (P = 0.056), and the values were significantly higher in patients who with MODS and in nonsurvivors than those in patients who without MODS and in survivors (both P < 0.05). Urine IFABP concentration was not found significantly difference in patients with APACHE II score > 20, those with MODS and nonsurvivors, compared with patients with APACHE II score < or = 20, those without MODS and survivors. Patients with stress ulcer had higher urine IFABP concentration than patients without stress ulcer (P < 0.05). There was no correlation among LMR, IFABP and gastrointestinal function score.

CONCLUSION

This study reveals that patients with sepsis have intestinal mucosal damage and increased intestinal permeability. Increased LMR in urine is associated with clinical severity and prognosis; urine IFABP concentration is not associated with clinical severity and prognosis. Patients with stress ulcer have higher urine IFABP concentration. There is no correlation among IFABP, LMR and gastrointestinal function score.

Assessment of small intestinal permeability using 1H-NMR spectroscopy

BACKGROUND

Evaluation of small intestinal permeability (SIP) is based on the estimation of the urinary excretion ratio of a large and a small molecule (lactulose and mannitol, L/M) after oral administration. We evaluated SIP using 1H-NMR spectroscopy.

METHODS

In-vitro experiments on known concentration of mannitol and lactulose solutions were performed to measure accuracy and precession of quantification using 1H-NMR spectroscopy. Eighteen patients with malabsorption syndrome (MAS) and 28 healthy subjects (HS) underwent SIP evaluation using L/M excretion ratio over 6-h after oral administration of 15 mL (10g) lactulose and 5 g mannitol using 1H-NMR spectroscopy and trimethyl silyl propionic acid as external reference and for quantification.

RESULTS

Median errors of estimation of mannitol and lactulose were 5% (range 1.2 to 5) and 1.3% (range 0.2 to 1.3), respectively in-vitro. Patients with MAS excreted higher quantity of lactulose in urine than HS (median 0.33 mmol vs 0.12, 0 to .676 mmol, p<0.008). There was a trend towards lower urinary excretion of mannitol in patients with MAS than HS (median 3.58, range 0.61 to 15.77 mmol vs. 3.82, 1.34 to 16.42 mmol, p = ns). L/M ratio was higher among patients with MAS as compared to HS (median 0.1172 vs 0.045, p< 0.002). A cut-off value of L/M excretion ratio by receiver-operating characteristic (ROC) curve of 0.049 had a sensitivity and specificity of 72% and 61%, respectively; a cut-off value of 0.078 had a specificity of 90% but low sensitivity (67%). Area under ROC curve was 0.77.

CONCLUSION

1H-NMR spectroscopy is an analytical tool for assessment of SIP with reasonable sensitivity and specificity.

Intestinal permeability and malabsorption of rifampin and isoniazid in active pulmonary tuberculosis

Low antimycobacterial drug concentrations have been observed in tuberculosis (TB) patients under treatment. The lactulose/mannitol urinary excretion test (L/M), normally used to measure intestinal permeability, may be useful to assess drug absorption. The objective of this research was to study intestinal absorptive function and bioavailability of rifampin and isoniazid in TB patients. A cross sectional study was done with 41 patients and 28 healthy controls, using the L/M test. The bioavailabilities of rifampin (R) and isoniazid (H) were evaluated in 18 patients receiving full doses. Urinary excretion of mannitol and lactulose, measured by HPLC, was significantly lower in TB patients. The serum concentrations of the drugs were below the expected range for R (8-24 mcg/mL) or H (3-6 mcg/mL) in 16/18 patients. Analyzing the drugs individually, 12/18 patients had low serum concentrations of R, 13/18 for H and 8/18 for both drugs. We suggest that there is a decrease in the functional absorptive area of the intestine in TB patients, which would explain the reduced serum concentrations of antituberculosis drugs. There is a need for new approaches to improve drug bioavailability in TB patients.

Measurement of intestinal mucosal permeability in dogs with lymphocytic-plasmacytic enteritis

Lymphocytic-plasmacytic enteritis (LPE) is a type of canine inflammatory bowel disease (IBD). One of its most probable causes is a defect in the mucosal permeability barrier. In the present study, intestinal permeability in LPE dogs was examinated to evaluate its clinical value. Twenty-nine dogs with LPE diagnosed by clinical and histological examinations were included in this study. Intestinal permeability was evaluated by measuring the ratio of the concentrations of two sugars (lactulose (L) and rhamnose (R)) with different molecular weights in urine samples after oral administration of a solution containing them. Biopsy specimens of duodenum were evaluated according to histological criteria. The urinary L:R ratio in the 29 LPE dogs (1.68 +/- 1.17, mean +/- SD) was significantly higher than that in the 10 healthy control dogs (0.75 +/- 0.38, P<0.01). In the LPE dogs, a weak correlation was observed between the histopathological grading score of the duodenum and the urinary L:R ratio (r=0.408, P<0.05). The urinary L:R ratio in the 20 dogs showing hypoalbuminemia (< 2.5 g/dl) was significantly higher than that in the 9 dogs with normal serum albumin levels > 2.5 g/dl (P<0.01). In conclusion, permeability of the intestinal mucosa as determined by the urinary L:R ratio could be a useful laboratory parameter for evaluating intestinal damage in LPE dogs.

Fluid restriction during running increases GI permeability

The purpose of this study was to determine gastrointestinal (GI) permeability during prolonged treadmill running (60 min at 70 % V.O2max) with and without fluid intake (3 ml/kg body mass/10 min). Twenty runners (11 males, 9 females; age = 22 +/- 3 (SD) yrs; mean V.O2max = 55.7 +/- 5.0 ml/kg/min) completed four experiments: 1) rest, 2) running with no fluid (NF), 3) running with ingestion of a 4 % glucose solution (GLU), and 4) running with ingestion of a water placebo (PLA). To determine GI permeability, subjects also drank a solution containing 5 g sucrose (S), 5 g lactulose (L), and 2 g rhamnose (R) immediately prior to each trial. Gastroduodenal permeability was determined by urinary S excretion, while small intestinal permeability was determined by the L/R excretion ratio. Percent body mass loss (i.e., dehydration) was negligible during rest, GLU and PLA, while NF resulted in a 1.5 % loss of body mass (p < 0.05). Gastroduodenal and intestinal permeability were significantly (p < 0.008) increased in NF compared to rest. There were no other differences in GI permeability. These results indicate that fluid restriction during 1 h of steady-state running increases GI permeability above resting levels.

Effects of oral adenosine 5'-triphosphate and adenosine in enteric-coated capsules on indomethacin-induced permeability changes in the human small intestine: a randomized cross-over study

Background

It is well-known that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause damage to the small bowel associated with disruption of mucosal barrier function. In healthy human volunteers, we showed previously that topical administration of adenosine 5'-triphosphate (ATP) by naso-intestinal tube attenuated a rise in small intestinal permeability induced by short-term challenge with the NSAID indomethacin. This finding suggested that ATP may be involved in the preservation of intestinal barrier function. Our current objective was to corroborate the favourable effect of ATP on indomethacin-induced permeability changes in healthy human volunteers when ATP is administered via enteric-coated capsules, which is a more practically feasible mode of administration. Since ATP effects may have been partly mediated through its breakdown to adenosine, effects of encapsulated adenosine were tested also.

Methods

By ingesting a test drink containing 5 g lactulose and 0.5 g L-rhamnose followed by five-hour collection of total urine, small intestinal permeability was assessed in 33 healthy human volunteers by measuring the urinary lactulose/rhamnose excretion ratio. Urinary excretion of lactulose and L-rhamnose was determined by fluorescent detection high-pressure liquid chromatography (HPLC). Basal permeability of the small intestine was assessed as a control condition (no indomethacin, no ATP/adenosine). As a model of increased small intestinal permeability, two dosages of indomethacin were ingested at 10 h (75 mg) and 1 h (50 mg) before ingesting the lactulose/rhamnose test drink. At 1.5 h before indomethacin ingestion, two dosages of placebo, ATP (2 g per dosage) or adenosine (1 g per dosage) were administered via enteric-coated hydroxypropyl methylcellulose (HPMC) capsules with Eudragit^© L30D-55.

Results

Median urinary lactulose/rhamnose excretion ratio (g/g) in the control condition was 0.032 (interquartile range: 0.022–0.044). Compared to the control condition, lactulose/rhamnose ratio after ingestion of indomethacin plus placebo was significantly increased to 0.039 (0.035–0.068); P < 0.01). The indomethacin-induced increase was neither affected by administration of encapsulated ATP (0.047 (0.033–0.065)) nor adenosine (0.050 (0.030–0.067)). Differences in L/R ratios between the conditions with indomethacin plus placebo, ATP or adenosine were not significant.

Conclusion

In this study, either ATP or adenosine administered via enteric-coated capsules had no effect on indomethacin-induced small intestinal permeability changes in healthy human volunteers. The observed lack of effect of encapsulated ATP/adenosine may have been caused by opening of the enteric-coated supplement at a site distal from the indomethacin-inflicted site. Further studies on site-specific effectiveness of ATP/adenosine on intestinal permeability changes are warranted.

[Effect of hepatocyte growth factor on intestinal permeability and bacterial translocation after small bowel transplantation in rat]

OBJECTIVE

To evaluate the effect of hepatocyte growth factor (HGF) on intestinal permeability and bacterial translocation after small bowel transplantation in rats.

METHODS

Twenty Wistar rats were as receptors and twenty SD rats as donors. After heterotopic intestinal grafting, cyclosporine A was administered at 6 mg/kg x day intramuscularly for inhibiting rejection. The SD rats were divided into 2 groups (n = 10). HGF was administered at 150 microg/kg x day (HGF group) and normal saline was administered at 150 microg/kg x day (control group). Intestinal permeability and bacterial translocation to the mesenteric lymph nodes and portal vein were assessed at the 8th postoperative day.

RESULTS

The lactulose and lactulose/ mannitol of control group (0.0931%+/-0.0085% and 0.132+/-0.021) were higher than those of normal reference value (0.0150%+/-0.0020% and 0.020+/-0.005) (P < 0.05). The lactulose and lactulose/ mannitol of HGF group (0.0396%+/-0.0090% and 0.056+/-0.013) were also higher than those of normal reference value (P<0.05). The bacterial culture positive proportion of lymphaden in HGF group and control group were 10% and 60%, showing statistically significant difference (P<0.05). The bacterial culture positive proportion of portal vein in HGF group and control group were 10% and 20% respectively (P>0.05).

CONCLUSION

HGF can decrease intestinal permeability and bacterial translocation from the lumen of the graft to the mesenteric lymph nodes, thus improve gut barrier function, may be of help to reduce the incidence of septic complications after intestinal grafting.

Intestinal permeability and antigliadin antibody test for monitoring adult patients with celiac disease

Celiac disease causes chronic inflammation of the intestinal mucosa and reduces surface absorption; after the withdrawal of gluten from the diet, there are clinical and histologic improvements. The intestinal permeability test and serologic tests are useful for confirming the diagnosis and monitoring patients. The goal of this study is to compare the antigliadin antibody (AGA) test with the intestinal permeability test for celiac patients on a gluten-free diet. The sample consisted of 22 celiac patients who were antigliadin immunoglobulin A-positive before treatment. After 12 months on a gluten-free diet, AGA testing was repeated and the intestinal permeability test was performed. A control group was composed of 11 healthy individuals. AGA remained positive in 40.9% of celiac patients, and the mean urinary lactulose excretion was 10.27%, that of mannitol was 10.18%, and the lactulose/mannitol ratio was 1.02. In the subgroup in which antigliadin became negative (59.1%), the value for lactulose was 3.79%, that for mannitol was 11.12%, the lactulose/mannitol ratio was 0.38, and the p value was less than 0.0001, 0.66, and less than 0.0001, respectively. When the two celiac subgroups were compared with the control group, the urinary lactulose excretion and the lactulose/mannitol ratio was less in the control group, whereas urinary mannitol excretion was greater. The p values were less than 0.0001 for the three variables, suggesting persistent lesions in mucosa of both subgroups, although to a lesser degree for those that became AGA negative. It is concluded that intestinal permeability allows a more precise clinical physiopathologic correlation than antigliadin and offers more information for the monitoring of these patients.

Local effect of adenosine 5'-triphosphate on indomethacin-induced permeability changes in the human small intestine

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use is associated with an elevated risk of gastrointestinal damage. As adenosine 5'-triphosphate (ATP) may play a protective role in the small intestine, our objective was to determine the local effect of ATP on small intestinal permeability changes induced by short-term challenge of the NSAID indomethacin in healthy humans.

METHODS

Mucosal permeability of the small intestine was assessed by the lactulose/rhamnose permeability test, that is, ingestion of a test drink containing 5 g lactulose and 0.5 g L-rhamnose followed by total urine collection for 5 h. Urinary excretion of lactulose and L-rhamnose was determined by fluorescent detection high-pressure liquid chromatography (HPLC). Basal small intestinal permeability was assessed as a control condition. As a model of increased small intestinal permeability, two doses of indomethacin were ingested before ingestion of the test drink (75 mg and 50 mg at 10 h and 1 h before the test drink, respectively). Concomitantly with indomethacin ingestion, placebo or 30 mg/kg ATP was administered through a naso-intestinal tube.

RESULTS

Median urinary lactulose/rhamnose ratio (g/g) in the control condition was 0.023 (interquartile range: 0.013-0.041). Compared with the control condition, urinary lactulose/rhamnose ratio after ingestion of indomethacin and administration of placebo was significantly increased [0.042 (0.028-0.076); P<0.01]. In contrast, urinary lactulose/rhamnose ratio after indomethacin ingestion plus ATP administration [0.027 (0.020-0.046)] was significantly lower than the lactulose/rhamnose ratio in the placebo condition (P<0.01).

CONCLUSIONS

Topical ATP administration into the small intestine during short-term challenge of the NSAID indomethacin attenuates the NSAID-induced increase in small intestinal permeability in healthy humans.

Intestinal permeability in different feedings in infancy

AIM

To determine the intestinal permeability (IP) as a marker of intestinal epithelial integrity in formula-fed infants compared with healthy breast-fed infants.

METHODS

IP was measured in 57 healthy infants less than 4 months old. A dual sugar test with lactulose and mannitol was performed. Three urinary ratios were established: lactulose/mannitol (L/M), lactulose/creatinine (L/C) and mannitol/creatinine (M/C). Five groups were studied: breast-fed (n = 11), prebiotic supplemented formula (n 17), nucleotides supplemented formula (n = 9), LC-PUFA supplemented formula (n = 9) and LC-PUFA and nucleotides supplemented formula (n = 11).

RESULTS

We have not found any difference in IP between breast-fed and formula-fed infants nor when the different formulas are compared with each other. The indirect information of the paracellular pathway by the ratio L/C and the transcellular route by the ratio M/C reflects some difference when the ingredients added are fructooligosaccharides and galactooligosaccharides, expressing a higher degree of lactulose permeation with respect to mannitol. When LC-PUFA supplementation was evaluated a lesser ratio of L/C was found, expressing intestinal barrier related to a process of epithelial tight.

CONCLUSIONS

The most important factor in the maintenance of the integrity of epithelial barrier function is probably the delivery of nutrients in the gastrointestinal tract. The role of the different ingredients added should be clarified.

Effect of hyperbilirubinemia on intestinal permeability in healthy term newborns

We investigated the effect of serum bilirubin (SB) on intestinal permeability (IP) of healthy, term, birth weight appropriate for gestational age neonates before phototherapy. IP was measured by the dual probe (lactulose/mannitol) sugar absorption test (SAT) performed on the third day of life in 12 healthy jaundiced newborns (total bilirubin 249 +/- 39.75 micromol/L) and compared to that of 12 non-jaundiced newborns (total bilirubin 83.79 + 37.62 micromol/L) matched for sex, gestational age, birth weight and Apgar score. Jaundiced newborns have a significantly higher La/Ma ratio than non-jaundiced (0.31 +/- 0.28 vs. 0.053 +/- 0.043; p < 0.0004). A significant correlation was found between serum bilirubin level and La/Ma ratio (r = 0.56 p < 0.006).

CONCLUSION

Our study demonstrates a direct effect of UCB on gut epithelial barrier of at-term newborns in whom UCB appears to be responsible for an alteration of IP that theoretically may lead to a passage of macromolecules through the intestinal epithelium increasing the risk of sensitization.

The effect of glutamine-enriched enteral nutrition on intestinal permeability in very-low-birth-weight infants: a randomized controlled trial

BACKGROUND

Very-low-birth-weight (VLBW) infants are susceptible to glutamine depletion. Glutamine depletion has negative effects on intestinal integrity. The lower infection rate in VLBW infants receiving glutamine-enriched enteral nutrition may originate from improved intestinal integrity, as reflected by decreased intestinal permeability. The aim of our study was to investigate whether glutamine-enriched enteral nutrition in VLBW infants enhances the normal decrease in intestinal permeability, as measured by the sugar absorption test (SAT).

METHODS

In a double-blind, randomized, placebo-controlled trial, VLBW infants (gestational age <32 weeks or birth weight <1,500 g) received enteral glutamine supplementation (0.3 g/kg/d) or an isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Intestinal permeability, determined from the urinary lactulose/mannitol (L/M) ratio after an oral dose of lactulose and mannitol, was assessed at 4 time points: before the start of the study, and at days 7, 14, and 30 of life.

RESULTS

At least 2 SATs were performed in 45/52 (86%) and 45/50 (90%) infants in the glutamine-supplemented and control groups, respectively. Baseline patient and nutrition characteristics were not different between the groups. There was no effect of glutamine-enriched enteral nutrition on the decrease of the L/M ratio between the start and end of the study (p = .78). In both treatment groups, median urinary lactulose concentrations decreased (p < .001), whereas median urinary mannitol concentrations increased (p = .003).

CONCLUSIONS

Glutamine-enriched enteral nutrition does not enhance the postnatal decrease in intestinal permeability in VLBW infants. Any beneficial effect of glutamine may involve other aspects of intestinal integrity; for example, modulation of the intestinal inflammatory response.

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.

Intestinal Permeability and Cytokine Inflammatory Response in Multiply Injured Patients

In experimental settings, the increased intestinal permeability (IP) following severe trauma is associated with increased serum concentrations of cytokines. Multiply injured patients are susceptible to the development of multiple organ failure (MOF). The aim of this study was to determine if altered IP after trauma was associated with upregulation of cytokines and if cytokines and IP influenced the development of MOF. In 30 multiply injured patients, IP was measured on days 2 and 4 after injury using the lactulose-mannitol (L-M) test, and the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-8 were determined simultaneously. The L-M ratio increased significantly from 0.049 (0.017-0.133) on day 2 to 0.150 (0.059-0.339) on day 4 (p < 0.02) On day 4, a significant correlation was also found between the L-M ratio and IL-6 (r = 0.43, p < 0.03). The IL-6 level on days 2 and 4 was significantly (p < 0.01 and p < 0.03, respectively) higher in MOF patients than in those without MOF, as was the TNF-alpha level on day 4 significantly higher (p < 0.04) in MOF patients. IP increases following multiple trauma, and on day 4 it correlates with the IL-6 level. However, in patients who develop MOF only cytokines are invariably increased, with IL-6 alone being significantly increased on both measurements in these patients.

Lactulose and mannitol intestinal permeability detected by capillary electrophoresis

Aim of this study was to set up a method by capillary electrophoresis to detect lactulose and mannitol in urine after an oral load, and to estimate the intestinal permeability in controls and in type I diabetes patients. The underivatized carbohydrates were monitored by indirect UV detection using sorbate, cetyltrimethylammonium bromide and LiOH as background electrolyte. Urines were purified by solid phase extraction, shaken with cation exchange resin, filtered and analysed. Carbohydrates migrated in <10 min in relation to their pK(a) and M(r). Controls (n = 33) and patients (n = 23) had an excretion ratio lactulose/mannitol 0.025 (0.018-0.051) and 0.067 (0.050-0.127), respectively (p < 0.01, median, interquartile range).

Is a leaky gut involved in the pathogenesis of intrahepatic cholestasis of pregnancy?

Increased gastrointestinal permeability has been demonstrated in several liver diseases. It may facilitate the absorption of gut-derived endotoxin-stimulating Kupffer cells to release proinflammatory cytokines or other potentially hepatotoxic compounds. We examined gastrointestinal permeability, plasma levels of anti-lipopolysacharides (anti-LPS), and four proinflammatory cytokines in 20 patients with intrahepatic cholestasis of pregnancy (ICP) compared with 22 normal pregnant and 29 non-pregnant women. Urinary excretion of sucrose and the urinary lactulose/mannitol (L/M) ratio after a standard oral load were used to assess gastrointestinal permeability. Anti-LPS (IgA, IgM, and IgG) were measured in peripheral blood by Human EndoCAb test kit; TNF-alpha, IL-1beta, IL-6, and IL-10 by Quantikine HS human immunoassays. Sucrose urinary excretion was similar in the three groups, indicating normal gastric permeability. The urinary L/M ratio was significantly higher in ICP than in the other groups [median (interquartile range): 0.018% (0.011-0.023) in ICP, 0.012% (0.009-0.016) in normal pregnancies, and 0.009% (0.008-0.012) in non-pregnant women, P < .01]. No significant differences were found in anti-LPS or cytokines plasma levels except slightly higher levels of IL-6 in ICP patients than in non-pregnant women (P < .05). Four of five women with abnormal urinary L/M ratio during ICP continued to show abnormalities in tests up to 2 years after delivery. In conclusion, an increased intestinal permeability was detected in ICP patients during and after pregnancy. A "leaky gut" may participate in the pathogenesis of ICP by enhancing the absorption of bacterial endotoxin and the enterohepatic circulation of cholestatic metabolites of sex hormones and bile salts.

Iron supplementation increases small intestine permeability in primary schoolchildren in Lusaka, Zambia

Elevated intestinal permeability, measured as an increased lactulose:mannitol (L:M) ratio, indicates injury of the small intestinal mucosa. As part of a randomized iron and multi-micronutrient (without iron) supplementation trial (Nchito et al., 2004), we determined intestinal permeability in a subgroup of schoolchildren at 10 months' follow-up to assess the effect of the interventions. Among 153 children (mean age 10.2 years and 53.6% girls) iron supplementation resulted in a higher L:M ratio compared with placebo (0.29 vs. 0.21, P=0.025). There was no effect of multi-micronutrient supplementation, and no interaction between the interventions. The finding could be one of the mechanisms explaining the negative effects of medicinal iron supplementation on morbidity found in some other studies.

Glutamine-enriched total parenteral nutrition in patients with inflammatory bowel disease

BACKGROUND

Studies in animal models of inflammatory bowel disease (IBD) suggest that supplementation of total parenteral nutrition with glutamine (gln), a conditionally essential amino acid in catabolic conditions, increases gln plasma concentrations, reduces intestinal damage, improves nitrogen balance and may improve the course of the disease. However, human data supporting this assumption are missing.

METHODS

A total of 24 consecutive patients with an acute exacerbation of IBD (19 Crohn's disease; five ulcerative colitis) and scheduled for total parenteral nutrition (TPN) (>7 days) were randomised. Parallel to a standardised anti-inflammatory therapy, the patients received either a TPN with 1.5 g/kg body weight of a standard amino acid or an isonitrogenic, isocaloric TPN with 1.2 g/kg body weight of a standard amino acid and 0.3 g/kg L-alanine-L-glutamine. Primary end points were gln plasma concentrations and intestinal permeability assessed by urinary lactulose and D-xylose ratio.

RESULTS

Gln plasma levels did not differ significantly in either group throughout the study. Intestinal permeability did not change within 7 days either with or without gln supplementation (Delta-lactulose/xylose ratio: 0.01+/-0.05 (gln+) vs 0.02+/-0.1 (gln-)). The observed changes in inflammatory and nutritional parameters, and also disease activity, length of TPN and hospital stay, were independent of glutamine substitution. Five (41%) patients in the gln+ group and three (25%) patients in the gln- group needed surgical intervention.

CONCLUSION

Although limited by the sample size, these results do not support the hypothesis that glutamine substitution has an obvious biochemical or clinical benefit in patients with active IBD scheduled for total parenteral nutrition.

Effect of Lactobacillus GG on intestinal integrity in Malawian children at risk of tropical enteropathy

BACKGROUND

Tropical enteropathy is an asymptomatic villous atrophy of the small bowel that is prevalent in the developing world and is associated with altered intestinal function and integrity. The histology of tropical enteropathy resembles that seen in small-bowel bacterial overgrowth.

OBJECTIVE

This study tested the hypothesis that treatment of 3-5-y-old Malawian children with the probiotic Lactobacillus GG would improve their intestinal function and integrity.

DESIGN

Clinically healthy children (n = 164) were enrolled in a placebo-controlled, randomized, double-blind trial. Intestinal function and integrity were measured by using the site-specific sugar-absorption test before and after 30 d of treatment with Lactobacillus GG or placebo. The primary outcomes were the ratios of urinary lactulose to mannitol (L:M) and of urinary sucrose to lactulose (S:L) excretion.

RESULTS

Of the 161 children who completed the study, 119 (73%) had tropical enteropathy on enrollment (L:M > 0.10). Children receiving Lactobacillus GG did not differ significantly from the placebo group in the excretion (in % of dose administered) of mannitol (mean +/- SD: 8.9 +/- 4.4 and 8.9 +/- 3.9, respectively), lactulose (0.31 +/- 0.20 and 0.33 +/- 0.23, respectively), or sucrose (0.078 +/- 0.058 and 0.082 +/- 0.075, respectively). L:M and S:L also did not differ significantly between the Lactobacillus and placebo groups (0.19 +/- 0.13 and 0.20 +/- 0.12, respectively, for L:M; 0.58 +/- 0.46 and 0.65 +/- 0.57, respectively, for S:L).

CONCLUSION

Administration of Lactobacillus GG for 30 d had no effect on the intestinal integrity of 3-5-y-old Malawian children.

Prospective evaluation of gut mucosal barrier injury following various myeloablative regimens for haematopoietic stem cell transplant

We determined gut mucosal barrier injury (MBI) among 129 recipients of an allogeneic or autologous haematopoietic stem cell transplant (HSCT) who had been given different myeloablative regimens by measuring integrity using the lactulose/rhamnose (RHA) ratio and absorption using the ratios of rhamnose/3-O-methylglucose and xylose/3-O-methylglucose. Regimens that did not contain idarubicin induced oral mucositis and disturbed gut integrity and absorption earlier than did those containing the anthracycline. By contrast, regimens containing idarubicin induced more severe and prolonged oral and gut MBI. Gut integrity and absorption of most patients were still abnormal at discharge from hospital. These results confirm that the integrity and absorptive capacity of the gut is affected adversely by myeloablative regimens in general, although only two patterns of mucosal injury emerged depending on whether or not idarubicin was used.

Prebiotic ingestion does not improve gastrointestinal barrier function in burn patients

Prebiotics increase intestinal levels of health-promoting bacteria implicated in decreasing pathogen colonization, stimulating immune functions and stabilizing gut barrier functions, parameters which are altered in burn patients. We propose that regular intake of a prebiotic, oligofructose (OF), might help to improve the altered gastrointestinal (GI) permeability observed in burn patients. A randomized, double-blind, controlled clinical trial was carried out in 41 burn patients (mean burn surface area=17.1+/-8.2%) who ingested daily 6 g of oligofructose (OF group) or sucrose as placebo (Control group) during 15 days. Gastrointestinal permeability to sucrose and lactulose/mannitol (L/M) was evaluated on days 1 (before treatment) 3, 7, 14 and 21. A permeability test was also performed in 18 healthy subjects as controls. Thirty-one patients completed the protocol (dropout rate=24.4%). Healthy subjects had a basal sucrose excretion of 21.3 mg (14.0-32.5 mg) and a basal L/M ratio of 0.017% (0.009-0.022%). Sucrose excretion increased 5-fold and L/M ratio 4.4-fold in burn patients on day 1 and these high levels of marker excretion decreased significantly throughout the study (p=0.016 and 0.000001, respectively). No differences between the OF and Control groups were observed for sucrose excretion or L/M ratio. In conclusion, the normalization of gastrointestinal permeability is not accelerated by prebiotic intake.

Evaluation of a triple sugar test of colonic permeability in humans

AIM

Conventional dual sugar tests of intestinal permeability assess only the stomach and small intestine. A novel triple sugar method of assessing colonic permeability has recently been described in animals. This utilizes the non-fermented sweetener sucralose, in addition to conventional sugars. It has been postulated that this test enables the simultaneous assessment of small-intestinal and colonic barrier function in humans. The aim of this study was to evaluate the triple sugar test using healthy volunteers and ileostomists.

METHODS

Twenty-one healthy volunteers and 18 ileostomists underwent the triple sugar test. After an overnight fast, subjects drank a solution containing lactulose (5 g), rhamnose (1 g) and sucralose (5 g). Urine was collected for 0-5 h and 5-19 h. Urinary sugars were quantified using HPLC, and 5 and 24-h excretion calculated. Nineteen control subjects and 16 ileostomists also underwent a 51Cr-EDTA permeability test. Permeability data were presented as medians (IQR), and differences between groups analysed with Mann-Whitney U-tests.

RESULTS

Lactulose excretion and the 5-h lactulose/rhamnose (L/R) ratio were similar in controls and ileostomists [L/R ratio 0.024 (0.022-0.034) vs. 0.025 (0.022-0.035), P = 0.955]. Twenty-four hours excretion of sucralose was significantly higher in control subjects compared with ileostomists [1.41% (1.17-1.68) vs. 0.96% (0.64-1.2), P = 0.003]. The same pattern was seen with 51Cr-EDTA [2.73% (2.06-3.76) vs. 2.06% (1.55-2.71), P = 0.037] and with lactulose [0.52% (0.42-0.60) vs. 0.25% (0.16-0.35), P = 0.002].

CONCLUSIONS

Both sucralose and 51Cr-EDTA underwent significant colonic absorption. A significant amount of lactulose also appeared to be absorbed in the colon. This unexpected finding requires further study.