Intestinal permeability changes and excretion of micro-organisms in stools of infants with diarrhoea and vomiting

Rotavirus infection increases intestinal motility but not permeability at the onset of diarrhea

The disease mechanisms associated with onset and secondary effects of rotavirus (RV) diarrhea remain to be determined and may not be identical. In this study, we investigated whether onset of RV diarrhea is associated with increased intestinal permeability and/or motility. To study the transit time, fluorescent fluorescein isothiocyanate (FITC)-dextran was given to RV-infected adult and infant mice. Intestinal motility was also studied with an opioid receptor agonist (loperamide) and a muscarinic receptor antagonist (atropine). To investigate whether RV increases permeability at the onset of diarrhea, fluorescent 4- and 10-kDa dextran doses were given to infected and noninfected mice, and fluorescence intensity was measured subsequently in serum. RV increased transit time in infant mice. Increased motility was detected at 24 h postinfection (h p.i.) and persisted up to 72 h p.i in pups. Both loperamide and atropine decreased intestinal motility and attenuated diarrhea. Analysis of passage of fluorescent dextran from the intestine into serum indicated unaffected intestinal permeability at the onset of diarrhea (24 to 48 h p.i.). We show that RV-induced diarrhea is associated with increased intestinal motility via an activation of the myenteric nerve plexus, which in turn stimulates muscarinic receptors on intestinal smooth muscles.

IMPORTANCE

We show that RV-infected mice have increased intestinal motility at the onset of diarrhea, and that this is not associated with increased intestinal permeability. These new observations will contribute to a better understanding of the mechanisms involved in RV diarrhea.

Intestinal permeability and diarrhoeal disease in Aboriginal Australians

BACKGROUND

Northern Territory Aboriginal children hospitalised with acute gastroenteritis have high rates of acidosis, hypokalaemia, and dehydration.

AIMS

To determine whether Aboriginal children with and without diarrhoea have greater impairment in intestinal function than non-Aboriginal children, as assessed by increased permeability ratios.

METHODS

A descriptive study of 124 children (96 Aboriginal and 28 non-Aboriginal) hospitalised with and without diarrhoea. Intestinal permeability was assessed by the lactulose to rhamnose (L-R) ratio from a five hour urine collection.

RESULTS

In Aboriginal children, mean L-R ratios (95% confidence intervals) were 18.3 (17.1 to 19.6) with diarrhoea and 9.0 (7.3 to 11.0) without diarrhoea, and in non-Aboriginal children they were 5.9 (2.8 to 12. 3) and 4.2 (3.3 to 5.2), respectively. In patients with diarrhoea, L-R ratios were significantly raised when accompanied by acidosis (mean, 22.8; 95% CI, 17.0 to 30.5), hypokalaemia (mean, 20.7; 95% CI, 15.4 to 27.9), and >/= 5% dehydration (mean, 24.3; 95% CI, 19.0 to 29.6) compared with none of these complications (mean, 7.0; 95% CI, 3.5 to 13.8).

CONCLUSION

The high incidence of acidosis, hypokalaemia, and dehydration in Aboriginal children admitted with diarrhoeal disease is related to underlying small intestinal mucosal damage.

Geography of intestinal permeability and absorption

BACKGROUND

Intestinal morphology and function vary geographically.

AIMS

These functions were assessed in asymptomatic volunteers in European, North American, Middle Eastern, Asian, African, and Caribbean countries.

METHODS

Five hour urine collections were obtained from each subject following ingestion of a 100 ml iso-osmolar test solution containing 3-0-methyl-D-glucose, D-xylose, L-rhamnose, and lactulose after an overnight fast, to assess active (3-0-methyl-D-glucose) and passive (D-xylose) carrier mediated, and non-mediated (L-rhamnose) absorption capacity, as well as intestinal permeability (lactulose:rhamnose ratio).

RESULTS

A comparison of results for subjects from tropical countries (n=218) with those resident in the combined temperate and subtropical region (Europe, United States, Qatar) (n=224) showed significant differences. Residents in tropical areas had a higher mean lactulose:rhamnose ratio and lower mean five hour recoveries of 3-0-methyl-D-glucose, D-xylose, and L-rhamnose, indicating higher intestinal permeability and lower absorptive capacity. Investigation of visiting residents suggested that differences in intestinal permeability and absorptive capacity were related to the area of residence. Subjects from Texas and Qatar, although comprised of several ethnic groups and resident in a subtropical area, showed no significant difference from European subjects.

CONCLUSIONS

There are clearly demarcated variations in intestinal permeability and absorptive capacity affecting asymptomatic residents of different geographical areas which correspond with the condition described as tropical enteropathy. Results suggest the importance of environmental factors. The parameters investigated may be relevant to the predisposition of the indigenous population and travellers to diarrhoeal illness and malnutrition. Intestinal function in patients from the tropics may be difficult to interpret, but should take into account the range of values found in the asymptomatic normal population.

Zinc and diarrhea in infants

Due to dietary modifications including the intake of cereals, vegetables and the frequent use of soy milk instead of breast milk, children in developing countries with diarrhea frequently suffer from zinc deficiency. Furthermore, diarrhea leads to excess zinc losses. Beside low energy intake zinc deficiency contributes to continued diarrhea, which in turn accounts for half of the deaths from diarrhea in children. Zinc supplementation leads to accelerated regeneration of the mucosa, increased levels of brush-border enzymes, enhanced cellular immunity and higher levels of secretory antibodies. In addition, in stunted children zinc supplementation results in enhanced catch-up growth via higher levels of insulin-like growth factor-I. Growth retardation is closely related to the risk of diarrheal diseases in children. These pathophysiological conclusions are supported by several controlled clinical traits which have provided evidence that zinc supplementation results in significant reduction in the risk of continued diarrhea. However, it remains to be clarified whether these benefits are attributable to pharmacological effects or if they can be related to the correction of an underlying deficiency state.

Zinc supplementation in young children with acute diarrhea in India

BACKGROUND

In developing countries the duration and severity of diarrheal illnesses are greatest among infants and young children with malnutrition and impaired immune status, both factors that may be associated with zinc deficiency. In children with severe zinc deficiency, diarrhea is common and responds quickly to zinc supplementation.

METHODS

To evaluate the effects of daily supplementation with 20 mg of elemental zinc on the duration and severity of acute diarrhea, we conducted a double-blind, randomized, controlled trial involving 937 children, 6 to 35 months of age, in New Delhi, India. All the children also received oral rehydration therapy and vitamin supplements.

RESULTS

Among the children who received zinc supplementation, there was a 23 percent reduction (95 percent confidence interval, 12 percent to 32 percent) in the risk of continued diarrhea. Estimates of the likelihood of recovery according to the day of zinc supplementation revealed a reduction of 7 percent (95 percent confidence interval, -9 percent to +22 percent) in the risk of continued diarrhea during days 1 through 3 and a reduction of 38 percent (95 percent confidence interval, 27 percent to 48 percent) after day 3. When zinc supplementation was initiated within three days of the onset of diarrhea, there was a 39 percent reduction (95 percent confidence interval, 7 percent to 61 percent) in the proportion of episodes lasting more than seven days. In the zinc-supplementation group there was a decrease of 39 percent (95 percent confidence interval, 6 percent to 70 percent) in the mean number of watery stools per day (P = 0.02) and a decrease of 21 percent (95 percent confidence interval, 10 percent to 31 percent) in the number of days with watery diarrhea. The reductions in the duration and severity of diarrhea were greater in children with stunted growth than in those with normal growth.

CONCLUSION

For infants and young children with acute diarrhea, zinc supplementation results in clinically important reductions in the duration and severity of diarrhea.

Spot urine pancreolauryl test for use in infancy

As a simple non-invasive test of possible pancreatic insufficiency 10 healthy infants, 13 infants with cystic fibrosis, and nine infants with unexplained diarrhoea and failure to thrive were given an emulsion containing fluorescein dilaurate and mannitol by mouth. A spot urine specimen was collected and results expressed as urinary fluorescein to mannitol ratios. Sensitivity of the test was 96% and specificity was 95%.

Dual marker one day pancreolauryl test

There is a pressing need for a simple non-invasive test of exocrine pancreatic function for use in children. The pancreolauryl test has been modified by the addition of a second marker (mannitol) to achieve a single day test without the need for two timed urine collections. Six healthy subjects and nine patients with cystic fibrosis were studied. Fluorescein, fluorescein dilaurate, and mannitol were taken by mouth, alone or in combinations, followed by 10 hour urine collections in two hourly aliquots to study the comparative pharmacokinetics of these markers. Urinary fluorescein was determined spectrophotometrically and urinary mannitol enzymatically. When fluorescein dilaurate and mannitol were taken together and the results expressed as ratios of percentage fluorescein to percentage mannitol recovery (F:M ratio) (mean (SD)) there was clear discrimination between healthy subjects and those with cystic fibrosis regardless of enzyme replacement treatment (57.3 (18.2) v 3.4 (1.4) v 3.2 (1.6) respectively). The differences in F:M ratios reached statistical significance in urinary aliquots collected between two and eight hours after marker ingestion. This single day tubeless test will greatly simplify the investigation of the child with suspected exocrine pancreatic dysfunction.

Mucosal permeability to 51Cr EDTA following subclinical intestinal ischemia-reperfusion injury in the weanling rat

The etiology of necrotizing enterocolitis (NEC) is uncertain. We have hypothesized that subclinical intestinal ischemia might result in increased mucosal permeability to intraluminal toxins or bacteria, resulting in inflammation and NEC. In order to pursue this hypothesis, we designed a series of studies to investigate whether the first assumption is correct, ie whether a subclinical ischemia-reperfusion injury (IRI) results in increased mucosal permeability. Using a model of superior mesenteric artery occlusion (SMAO) in weanling rats, we initially defined 10-minute SMAO as "subclinical" IRI (ie, 100% survival, no histological changes, and no hemodynamic instability). Mucosal permeability to a standard probe molecule (51Cr EDTA) was then measured after sham operation, or 2-minute or 10-minute SMAO. There was an early increase in permeability 30 minutes after reperfusion in the 10-minute SMAO group, which was completely reversed by 2 hours. Further studies suggested that having passed through the mucosa, the probe entered the systemic circulation via both portal venous and intestinal lymphatic routes. Subclinical intestinal IRI results in an early, reversible increase in mucosal permeability to 51Cr EDTA, which may be important in the pathogenesis of NEC. Further studies are required to fully characterize this phenomenon, and to determine the mechanisms by which it occurs.

Gut regulatory peptides and intestinal permeability in acute infantile gastroenteritis

The plasma concentrations of seven gut regulatory peptides were measured in 11 infants suffering from acute gastroenteritis. Samples were taken at the time of the acute illness, upon reintroduction of feeding, and three months after recovery. These results were compared with controls. In the infants with diarrhoea, a massive increase in the fasting plasma mean (SEM) concentrations of enteroglucagon was found at the time of illness (1292 (312) v 79 (27) pmol/l), with concentrations of pancreatic glucagon, peptide tyrosine tyrosine, and motilin also being increased (17.8 (3.1) v 6.3 (1.1) pmol/l, 114.6 (15.2) v 37.0 (11.0) pmol/l, 217.6 (44.1) v 98.5 (18.3 pmol/l) respectively). The preprandial concentrations of motilin were found to be still increased at recovery (183.9 (35.4) pmol/l), but the concentrations of the other three peptides had returned to normal values. No differences in plasma concentrations of vasoactive intestinal polypeptide, neurotensin, or pancreatic polypeptide were found. An increased intestinal permeability was demonstrated at the time of diarrhoea by the urinary ratio of lactulose to mannitol, suggesting simultaneous gut damage. The effects of regulatory peptides may be relevant to the pathophysiology of gastroenteritis in infants.

Intestinal permeability in pediatric gastroenterology

The role of the physiologic barrier function of the small bowel and its possible role in health and disease has attracted much attention over the past decade. The intestinal mucosal barrier for luminal macromolecules and microorganism is the result of non-immunologic and immunologic defense mechanisms. The non-immunologic mechanisms consist of intraluminal factors such as gastric acid, proteolytic activity, and motility and of mucosal surface factors like mucin and the microvillous membrane. The immunologic mechanisms include secretary IgA and cell-mediated immunity. Both types of mechanism are not completely mature at birth. Maturation of this barrier is not finished before the 2nd year of life. One of the aspects of the mucosal barrier function can be estimated by the intestinal permeability (IP) for macromolecules. We use the differential sugar absorption test (SAT), in which the ratio of urinary excretion of a relatively large molecule, lactulose, is compared with that of a relatively small molecule, mannitol, after oral ingestion. Although the small intestine is permeable to certain macromolecules in normal developmental conditions, an increased IP could be involved in the pathophysiology of several diseases, including infectious diarrhea, food allergy, celiac disease, and Crohn's disease. It can be concluded that IP, as measured with the SAT, reflects the state of the mucosal barrier and is altered in several gastrointestinal diseases. The SAT is a non-invasive IP test that can be of diagnostic help to demonstrate alterations in the small-mucosal barrier function and may be useful to evaluate therapeutic interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal permeability in man: effects of acute systemic infections

Intestinal permeability was assessed (within 24-48h of admission to hospital) in 7 patients suffering from acute infections, mainly pneumonia. The permeability test involved administering an oral solution containing a mixture of lactulose (10 g) mannitol (5 g and 0.5 microCi) and (51)Cr-EDTA (30 microCi), and collecting urine samples before, and between 0-6, 6-12 and 12-24 h after dosing. The excretion of the markers was compared with the results obtained from 24 normal or control subjects and 15 patients with coeliac disease. None of the markers were excreted in significantly different amounts in the infected patients compared to the control subjects. In contrast, the coeliac patients excreted (0-6 h) four-fold more lactulose, three-fold more (51)Cr-EDTA and two-fold less mannitol than the normal subjects. The ratio of lactulose: mannitol and (51)Cr-EDTA: mannitol were therefore six- to eight-fold greater in the coeliac patients than in the normal subjects. The results confirm the sensitivity of the test for detecting the presence of an enteropathy but provide no evidence of a change in intestinal permeability in systemic infections studied under the stated conditions.

Pathophysiology of gastrointestinal mucosal permeability

The intestinal mucosa is composed of multiple barriers to the lumen-to-blood transport of solutes, including the unstirred water and mucous layers, the apical and basolateral cell membranes of the epithelial cell, the paracellular junctions, the interstitial matrix, and the capillary and lymphatic endothelia. The epithelial barrier appears effectively to restrict the movement of solutes with a radius as low as 3 A, yet it also permits limited permeation by molecules as large as albumin (36 A radius). There is evidence to suggest that the restrictive properties of the gastrointestinal mucosa are significantly altered under various physiological and pathological conditions, and measurement of plasma (or luminal) clearances of water-soluble molecules has proved to be a popular method for studying intestinal permeability. The aim of this review is to discuss the concept of the plasma clearance method, methodological aspects of the technique, factors that influence plasma-to-lumen clearance measurements (e.g. solute size, blood flow, and permeability of the epithelial cell barrier), and advantages and disadvantages of the clearance method. Finally, application of the clearance technique to the study of ischaemia/reperfusion-, ethanol-, and FMLP-induced mucosal injury will be described.

Urinary mannitol: lactulose excretion ratios and jejunal mucosal structure

A dual sugar (mannitol, lactulose) absorption test was evaluated using an iso-osmolar oral dose in two groups of children: a study group of 43 children divided into five subgroups, based on severity of mucosal damage, and a control group of 53 children with histologically normal jejunal biopsy specimens. After an oral dose, the three hour urinary mannitol: lactulose ratios in the control group showed a highly significant positive correlation with body surface area. After correction for the body surface area relationship, a control lower limit was defined by the mean -2SD of the log10 transformed control mannitol: lactulose ratios. Specificity and sensitivity for severe villous atrophy was 98% and 95% respectively but the sensitivity declined rapidly with decreasing degrees of mucosal damage, and the test would not therefore be an adequate screening procedure for all enteropathies. In sequential studies in 18 children, the changes in the mannitol: lactulose ratio were consistent with the changes in mucosal structure induced by gluten challenge or gluten withdrawal. The test may therefore have a role in any sequential study of lesions of the mucosa of the small intestine.

The impact of milk and weaning diet on gastrointestinal permeability in English and Gambian infants

To test the hypothesis that cow's milk formula and weaning diet may damage the gut mucosa, the gastrointestinal permeability of 77 healthy English and Gambian infants was measured from the urinary recovery of the markers lactulose and mannitol included in feeds. All infants were born at term and studied at 6, 12 and 18 weeks of age. No infant developed diarrhoea or failed to thrive. Infants fed on cow's milk formula had higher urinary lactulose: mannitol excretion ratios than breast-fed infants at 6 weeks of life (P less than 0.05). There was no significant difference in the urinary marker excretion ratios of English formula-fed and Gambian breast-fed infants at 12 weeks. An increase in urinary lactulose: mannitol excretion ratios was seen in all infants at 18 weeks. This was more probably due to increasing age than to the introduction of weaning diet. Cow's milk formula feeding was associated with greater intestinal permeability than breast feeding in infants aged 6 weeks. The introduction of weaning diet after 6 weeks did not appear to have an impact on the gastrointestinal permeability of healthy growing infants born in either England or rural Gambia.

Intestinal permeability during chemotherapy for childhood tumours

The intestinal permeability to mannitol and lactulose was measured in 29 children receiving treatment for solid tumours. At the time of study they had no gastrointestinal symptoms and appeared clinically well. However, there was a significant reduction in the absorption of mannitol when compared to normal children. This small bowel dysfunction may result in malabsorption of nutrients and drugs. There was a significant correlation between decreased mannitol absorption and low nutritional status.

Radionuclide tests for the assessment of intestinal permeability

14C labelled-D-mannitol and aquo (ethylene-diaminetriacetoacetic acid) 51chromium (III) (51Cr EDTA) have been evaluated as markers of intestinal permeability in twenty-four healthy control subjects, sixteen patients with recently diagnosed coeliac disease and twenty subjects with coeliac disease in remission on a gluten-free diet. The percentage excretion of 14C mannitol in urine collected for 6 h was significantly less in patients with coeliac disease (mean 6.7%) than controls (mean 13.5%). Conversely the excretion of 51Cr EDTA was significantly greater in patients with coeliac disease (mean 1.23%) compared with controls (mean 0.28%). The mean ratio of the percentage excretion of 51Cr to the percentage excretion of 14C was 0.29 in patients with untreated coeliac disease compared with 0.023 for healthy control subjects (P less than 0.001). Patients with untreated coeliac disease were clearly separated from control subjects by use of the 51Cr EDTA: 14C mannitol ratio but not by the excretion of independent markers.