This paper introduces a new type of system to simulate conditions in the large intestine. This system combines removal of metabolites and water with peristaltic mixing to obtain and handle physiological concentrations of microorganisms, dry matter and microbial metabolites. The system has been designed to be complementary to the dynamic multi-compartmental system that simulates conditions in the stomach and small intestine described by Minekus et al. [Minekus M, Marteau P, Havenaar R, Huis in't Veld JHJ (1995) ATLA 23:197-209]. High densities of microorganisms, comparable to those found in the colon in vivo, were achieved by absorption of water and dialysis of metabolites through hollow-fibre membranes inside the reactor compartments. The dense chyme was mixed and transported by peristaltic movements. The potential of the system as a tool to study fermentation was demonstrated in experiments with pectin, fructo-oligosaccharide, lactulose and lactitol as substrates. Parameters such as total acid production and short-chain fatty acid (SCFA) patterns were determined with time to characterize the fermentation. The stability of the microflora in the system was tested after inoculation with fresh fecal samples and after inoculation with a microflora that was maintained in a fermenter. Both approaches resulted in total anaerobic bacterial counts higher than 10(10) colony-forming units/ml with physiological levels of Bifidobacterium, Lactobacillus, Enterobacteriaceae and Clostridium. The dry matter content was approximately 10%, while the total SCFA concentration was maintained at physiological concentrations with similar molar ratios for acetic acid, propionic acid and butyric acid as measured in vivo.

A multicompartmental in vitro model has been described, which simulates the dynamic events occurring within the lumen of the gastrointestinal tract of man and monogastric animals. The accuracy of the model for reproducing in vivo data on gastrointestinal transit, pH, bile salt concentrations and the absorption of glucose was tested. The in vivo conditions simulated in the model were based on studies in healthy human volunteers. Mathematical modelling of gastric and ileal delivery with power exponential equations was used for the computer control of meal transit. The model appeared to reproduce accurately the pre-set data on meal transit, pH and bile salt concentrations in the different gastrointestinal compartments. Glucose absorption from the small intestine was almost complete. This model reproduces very closely the dynamic conditions based on the in vivo situation in monogastric animals and man. Therefore, the model can be an important tool in studying the fate of ingested components (for example, food, microorganisms and medicines) during gastrointestinal transit and, consequently, may contribute to the replacement of studies using laboratory animals.

Summary A protective effect of calcium against colorectal cancer has been described in Anglo-Saxon but not in Latin communities, and no such effect has been observed regarding adenomas. We investigated the relationship between calcium, dairy products and the adenoma-carcinoma sequence in a French region by comparing small adenoma (< 10 mm, n = 154), large adenoma (n = 208) and polyp-free (n = 426) subjects, and cancer cases (n = 171) with population controls (n = 309). There was no protective effect of calcium against colorectal tumours except for low fat calcium and large adenomas in men (OR for highest quintile= 0.3, P for trend = 0.06). There was even a trend towards an increased risk of cancer with dairy calcium in men and nondairy calcium in women. Vitamin D was inversely related to the risk of small adenomas in women (OR for highest quintile = 0.4, P for trend = 0.04). Regarding dairy products, only consumption of yoghurt displayed an inverse relationship with risk of large adenomas, in both men and women. These data failed to demonstrate a protective effect of calcium against colorectal carcinogenesis. They suggest that the type of dairy product might be the important factor with regard to prevention of colorectal tumours. (Benito et al., 1991;Tuyns et al., 1988; Negri et al., 1990). Dairy products have also been studied not only because they are the main source of dietary calcium, but also because other components may be of interest, such as the lactose content or the bacteria in fermented dairy products. To date, no significant association has been described between calcium intake and colorectal adenomas (Kampman et al., 1994a). This finding is all the more important since certain of the current intervention studies with calcium supplements use adenoma recurrence as an end point.France has a tradition of high calcium intake, mainly in the form of cheese. In order to define further the effect of calcium, phosphate, vitamin D and dairy product intake on the adenoma-carcinoma sequence, we carried out a casecontrol study in a French community of the relationship between these nutrients, as well as calcium-containing foods and the different macroscopic steps of colorectal carcinogenesis, namely small adenoma, large adenoma and cancer. Materials and methodsCases and controls A case-control study was set up between 1985 and 1990 to investigate risk factors for the different macroscopic steps of the adenoma-carcinoma sequence. Its general design has already been described Sample size calculations were based on fat intake, one of the suspected major risk factors for colorectal cancer. Considering the proportion of the population exposed to a high-fat diet, with a power of 80% to demonstrate a relative risk of 2.0 at the 5% level of significance, it was calculated that at least 140 cases and 280 controls were needed in each group.Two groups of patients with adenomas and polyp-free controls were selected from the endoscopy lists of all gastroenterologists in the area, whether in private or public practice. Adeno...

It has been suggested that the symptoms of irritable bowel syndrome (IBS) may be wrongly attributed to lactose intolerance. We examined the relations among IBS, demographic factors, living habits, and lactose intolerance. On the basis of a lactose tolerance test with ethanol, 101 of the 427 healthy subjects studied were lactose maldigesters and 326 were lactose digesters. IBS was diagnosed by means of the Bowel Disease Questionnaire, according to the Rome criteria. The use of dairy products and symptoms experienced after their consumption were recorded. IBS was found in 15% of both the lactose maldigesters and lactose digesters. One-third of the subjects reported intolerance to dairy products containing < or = 20 g lactose. About half of this third were lactose maldigesters and about half were lactose digesters. As explanations for this subjective lactose intolerance, the logistic regression model estimated lactose maldigestion (odds ratio: 10.3; 95% CI: 5.2, 20.4), IBS (4.6; 2.1, 10.1), experience of symptoms other than gastrointestinal ones (2.3; 1.2, 4.5), and female sex (2.1; 1.1, 4.0). Characteristics common to both subjective lactose intolerance and IBS were female sex and the experience of abdominal pain in childhood (P < 0.01). Age, regularity of meals, and the amount of physical activity were not associated with either subjective lactose intolerance or IBS. Of the subjects with IBS, the percentage of lactose maldigesters was the same as in the whole study group (24%) but the number who reported lactose intolerance was higher (60% compared with 27%, P < 0.001). We showed a strong relation among subjective lactose intolerance, IBS, the experience of abdominal pain in childhood, and female sex.

Objective: To determine the prevalence and clinical features of malnutrition and its relationship with the CFTR genotype in a cystic fibrosis (CF) adult population. Design: Cross-sectional study. Setting: