Relationship between small-intestinal transit rate and intestinal absorption of (14)C-labelled mannitol and (51)Cr-labelled ethylenediaminetetraacetic acid in healthy subjects

Intestinal barrier function in morbid obesity: results of a prospective study on the effect of sleeve gastrectomy

BACKGROUND

Obesity has been associated with impaired intestinal barrier function. It is not known whether bariatric surgery leads to changes in intestinal barrier function. We hypothesized that obesity is associated with disturbances in gastrointestinal barrier function, and that after bariatric surgery barrier function will improve.

METHODS

Prospective single center study in which we assessed segmental gut permeability by urinary recovery of a multisugar drink in 27 morbidly obese (BMI 43.3 ± 1.1 kg/m²) and 27 age and gender matched lean subjects (BMI 22.9 ± 0.43 kg/m²). Fecal calprotectin, SCFAs, plasma cytokines, and hsCRP were assessed as inflammatory and metabolic markers. Comparisons: (a) morbidly obese subjects vs. controls and (b) 2 and 6 months postsleeve vs. presleeve gastrectomy (n = 14). In another group of 10 morbidly obese and 11 matched lean subjects colonic and ileal biopsies were obtained in order to measure gene transcription of tight junction proteins.

RESULTS

Gastroduodenal permeability (urinary sucrose recovery) was significantly increased in obese vs. lean controls (p < 0.05). Small intestinal and colonic permeability (urinary recovery of lactulose/L-rhamnose and sucralose/erythritol, respectively) in obese subjects were not significantly different from controls. Morbidly obese subjects had a proinflammatory systemic and intestinal profile compared with lean subjects. After sleeve gastrectomy BMI decreased significantly (p < 0.001). Postsleeve gastroduodenal permeability normalized to values that do not differ from lean controls.

CONCLUSIONS

Gastroduodenal permeability, but not small intestinal or colonic permeability, is significantly increased in morbidly obese patients. After sleeve gastrectomy, gastroduodenal permeability normalized to values in the range of lean controls. Thus, the proximal gastrointestinal barrier is compromised in morbid obesity and is associated with a proinflammatory intestinal and systemic profile.

Chronic pancreatitis: Maldigestion, intestinal ecology and intestinal inflammation

Exocrine pancreatic insufficiency caused by chronic pancreatitis results from various factors which regulate digestion and absorption of nutrients. Pancreatic function has been extensively studied over the last 40 years, even if some aspects of secretion and gastrointestinal adaptation are not completely understood. The main clinical manifestations of exocrine pancreatic insufficiency are fat malabsorption, known as steatorrhea, which consists of fecal excretion of more than 6 g of fat per day, weight loss, abdominal discomfort and abdominal swelling sensation. Fat malabsorption also results in a deficit of fat-soluble vitamins (A, D, E and K) with consequent clinical manifestations. The relationships between pancreatic maldigestion, intestinal ecology and intestinal inflammation have not received particular attention, even if in clinical practice these mechanisms may be responsible for the low efficacy of pancreatic extracts in abolishing steatorrhea in some patients. The best treatments for pancreatic maldigestion should be re-evaluated, taking into account not only the correction of pancreatic insufficiency using pancreatic extracts and the best duodenal pH to permit optimal efficacy of these extracts, but we also need to consider other therapeutic approaches including the decontamination of intestinal lumen, supplementation of bile acids and, probably, the use of probiotics which may attenuate intestinal inflammation in chronic pancreatitis patients.

Small-bowel permeability in collagenous colitis

OBJECTIVE

Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small-intestinal biopsies, indicating that CC is a pan-intestinal disease. In small-intestinal disease, the intestinal barrier function may be impaired, and the permeability of the small intestine altered. The purpose of this research was to study small-bowel function in patients with CC as expressed by intestinal permeability.

MATERIAL AND METHODS

Ten patients with CC and chronic diarrhoea participated in the study. Coeliac disease was excluded by small-bowel biopsy and/or serology. Intestinal permeability was assessed as urinary excretion (ratios) 2, 4 and 6 h after ingestion of 14C-labelled mannitol (14C-mannitol) and 99mTc-labelled diethylenetriamine-pentaacetic acid (99mTc-DTPA). Data were compared with the results from healthy controls.

RESULTS

No difference was found between groups in urinary excretion of 14C-mannitol and 99mTc-DTPA after 2, 4 or 6 h, respectively. Likewise, no significant differences in the 99mTc-DTPA/14C-mannitol ratios between patients and controls were detected after 2 h: 0.030 (0.008-0.130) versus 0.020 (0.007-0.030), p = 0.19, after 4 h: 0.040 (0.009-0.180) versus 0.020 (0.008-0.040), p = 0.14 or after 6 h: 0.040 (0.012-0.180) versus 0.020 (0.010-0.040), p = 0.17.

CONCLUSIONS

No alterations in intestinal permeability in patients with CC could be demonstrated. Impairment of the integrity of the mucosa of the small bowel and the presence of a general dysfunction of the small intestine in patients with CC seem unlikely.

Abnormal intestinal permeability in subgroups of diarrhea-predominant irritable bowel syndromes

OBJECTIVES

Irritable bowel syndrome (IBS) is a heterogeneous condition and defined according to symptoms. Low-grade inflammation has been associated with IBS, particularly that following infection, but whether altered intestinal permeability profiles relate to irritable bowel subtype or onset is uncertain. Our aim was to compare small and large intestinal permeability in various subtypes of IBS to healthy controls.

METHODS

Intestinal permeability was measured using 1.8 MBq of 51Cr-EDTA and collecting urine over 24 h; Study 1: patients with diarrhea-predominant postinfectious IBS (N=15), constipation-predominant IBS (N=15), and healthy controls (N=15); Study 2: two groups of diarrhea-predominant IBS (D-IBS), one with a history of onset after acute gastroenteritis (postinfectious) (N=15) and the other without such a history (nonpostinfectious) (N=15) both compared with healthy controls (N=12).

RESULTS

Permeability expressed as percentage of total dose excreted in urine (median [inter-quartile range]). Study 1: Proximal small intestinal permeability was increased in postinfectious IBS (0.19 [0.12-0.23]) in contrast to constipated IBS (0.085 [0.043-0.13]) and controls (0.07 [0.035-0.19]) (p=0.02). IBS patients with eczema, asthma, or hayfever had increased proximal small intestinal permeability compared with IBS patients without atopy (p=0.02). Study 2: Small intestinal permeability was greater in nonpostinfectious diarrhea-predominant IBS (0.84 [0.69-1.49]) compared with postinfectious IBS (0.43 [0.29-0.63], p=0.028) or controls (0.27 [0.2-0.39]), p=0.001).

CONCLUSIONS

Small intestinal permeability is frequently abnormal in diarrhea-predominant IBS. Those without a history of infectious onset appear to have a more severe defect.

Bile acid malabsorption or disturbed intestinal permeability in patients treated with enzyme substitution for exocrine pancreatic insufficiency is not caused by bacterial overgrowth

INTRODUCTION

In some patients with severe exocrine pancreatic insufficiency, enzyme replacement therapy will not lead to clinical improvement or reduction of steatorrhea. Therefore, other mechanisms separately or in interplay with reduced enzyme secretion might be responsible for malabsorption in these patients.

AIMS

To evaluate the prevalence of bacterial overgrowth, bile acid absorption capacity, and intestinal permeability in a group of patients with well-characterized exocrine pancreatic insufficiency.

METHODOLOGY

Eleven men with severe exocrine pancreatic insufficiency, of whom 10 were receiving enzyme replacement therapy, were studied. The prevalence of bacterial overgrowth was evaluated by means of a hydrogen and methane breath test with glucose. Gamma camera scintigraphy after intake of 75Se-homocholic acid taurine (75Se-HCAT) was used to evaluate bile acid absorption capacity. Intestinal permeability was assessed from urine excretion of ingested 14C-mannitol and 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), and these data were compared with results for 10 age-matched healthy men.

RESULTS

No patients had abnormal breath hydrogen or methane concentrations after glucose intake. Abdominal retention of 75Se-HCAT was reduced in three of the patients. The patients had lower urine excretion of 14C-mannitol than the control subjects, whereas no difference was revealed in urine excretion of 99mTc-DTPA.

CONCLUSION

Bile acid absorption and small intestinal permeability might be affected in patients with exocrine pancreatic insufficiency who receive treatment with enzyme supplementation. The prevalence of bacterial overgrowth seems to be low among these patients and does not explain the findings.

Intestinal permeability in strongyloidiasis

The objective of the present study was to assess intestinal permeability in patients with infection caused by Strongyloides stercoralis. Twenty-six patients (16 women and 10 men), mean age 45.9, with a diagnosis of strongyloidiasis were evaluated. For comparison, 25 healthy volunteers (18 women and 7 men), mean age 44.9, without digestive disorders or intestinal parasites served as normal controls. Intestinal permeability was measured on the basis of urinary radioactivity levels during the 24 h following oral administration of chromium-labeled ethylenediaminetetraacetic acid ((51)Cr-EDTA) expressed as percentage of the ingested dose. The urinary excretion of (51)Cr-EDTA was significantly reduced in patients with strongyloidiasis compared to controls (1.60 +/- 0.74 and 3.10 +/- 1.40, respectively, P = 0.0001). Intestinal permeability is diminished in strongyloidiasis. Abnormalities in mucus secretion and intestinal motility and loss of macromolecules could explain the impaired intestinal permeability.

Evaluation of the lactulose/mannitol and 51Cr-ethylenediaminetetraacetic acid/14C-mannitol methods for intestinal permeability

BACKGROUND

We earlier compared the lactulose/mannitol and 51Cr-ethylenediaminetetraacetic acid (EDTA)/14C-mannitol methods for intestinal permeability We have now investigated an increased number of control subjects, with special regard to the influence of urinary volume, sex, age, and smoking on marker excretion, and patients with intestinal disorders, with special regard to correlations between markers.

METHODS

The 0- to 6-h urinary excretion of orally administered markers was measured in 65 control subjects and in 70 patients.

RESULTS

In the control group excretion of mannitol and 14C-mannitol (small-pore permeability markers) was strongly correlated to urinary volume, whereas such correlation was weak for lactulose and absent for 51Cr-EDTA (large-pore permeability markers). No sex difference in marker excretion was found, but correlation to urinary volume was more pronounced in males. There was a slightly decreasing excretion of markers with increasing age, reaching significance for 51Cr-EDTA and 14C-mannitol; their excretion ratio was unaffected. Smoking did not significantly affect marker excretion. In the patient group the excretion of large-pore markers tended to be higher and that of small-pore markers to be lower than in the control group; correlation between the large-pore markers, between the small-pore markers, and between the large-pore/small-pore marker ratios was higher than in the control group.

CONCLUSIONS

Correction for urinary volume substantially reduces variability in small-pore marker excretion. Excretion of both types of markers tends to decrease with age, the large-pore/small-pore marker ratio remaining unchanged. Smoking does not affect small-intestinal permeability. 14C-mannitol is preferred to chemically determined mannitol owing to lower test variability.