Elemental diet composition and the structure and function of rat small intestine: comparison of the effects of two diets on morphology and in vivo absorption of water

Intestinal adaptation after massive intestinal resection

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Intestinal adaptation after massive intestinal resection

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Transitioning the paediatric IBD patient to adult care

Transitioning an adolescent patient to an internist/gastroenterologist's care requires an understanding of the specific issues and challenges involved in the diagnosis and management of paediatric inflammatory bowel disease (IBD). Even though diagnostic criteria, as well as methods are the same in children and adults, younger patients may experience more insidious presentations. A high level of suspicion is necessary for an early and accurate diagnosis. Management of IBD in the paediatric population begins with the assessment of disease extent and activity as well as the identification of potentially serious complications (such as malnutrition, growth/sexual retardation and osteoporosis), which are often present at the time of diagnosis. Treatment includes not only medical, nutritional or surgical therapy but also a multidisciplinary or holistic approach taking into consideration the psychological as well as social impact of the disease on the patient and family.

Effects of cholestyramine and diet on small intestinal histomorphometry in rats

Reports on the effects of cholestyramine on small intestinal structure of rats have produced contradictory data about changes in mucosal histomorphometry, perhaps due to interacting effects of dietary composition. In order to identify effects of cholestyramine and diet on structure of the small intestines, 40 male rats were divided into 4 groups of 10 and fed 1 of each of the following diets for 1 month: standard diet, purified fiber-free diet, standard diet + 2% cholestyramine, or purified fiber-free diet + 2% cholestyramine. Serum concentrations of cholesterol and triglycerides were moderately increased in rats fed the purified fiber-free diet versus the standard diet. Neither total length nor weight of small intestine were affected by either diet or cholestyramine. Mucosal weight was affected by interactions between cholestyramine and diet, indicating that outcome depended upon modulating effects of both variables. Significant interactions were similarly detected among the variables of anatomic site, diet, and cholestyramine for many histomorphometric parameters of intestinal mucosa. Cholestyramine reduced total mucosal thickness in both jejunum and ileum and reduced villus height and villus:crypt ratio in the ileum.

Effects of an elemental diet, inert bulk and different types of dietary fibre on the response of the intestinal epithelium to refeeding in the rat and relationship to plasma gastrin, enteroglucagon, and PYY concentrations

Refeeding starved rats with an elemental diet resulted in a marked increase in crypt cell production rate (CCPR) in the proximal small intestine but not in the distal regions of the gut. Little effect on CCPR was noted when inert bulk (kaolin) was added to the elemental diet. Addition of a poorly fermentable dietary fibre (purified wood cellulose) had little effect on intestinal epithelial cell proliferation except in the distal colon where it significantly increased CCPR. A more readily fermentable fibre (purified wheat bran) caused a large proliferative response in the proximal, mid, and distal colon and in the distal small intestine. A gel forming fibre only significantly stimulated proliferation in the distal colon; the rats in this group, however, did not eat all the food given. There was no significant correlation between CCPR and plasma gastrin concentrations, but plasma enteroglucagon concentrations were significantly correlated with CCPR in almost all the sites studied. Plasma PYY concentrations also showed some correlation with CCPR, especially in the colon. Thus while inert bulk cannot stimulate colonic epithelial cell proliferation fermentable fibre is capable of stimulating proliferation in the colon, and especially in the distal colon: it can also stimulate proliferation in the distal small intestine and it is likely that plasma enteroglucagon may have a role to play in this process.

Effects of addition of kaolin or cellulose to an elemental diet on intestinal cell proliferation in the mouse

1. Various methods of estimating intestinal mass and cell proliferation were used to compare the effects of a pelleted laboratory diet (diet A), an elemental diet (Flexical; diet B), Flexical plus kaolin (diet C) and Flexical plus cellulose (diet D) on the mucosa and other tissues of the mouse small intestine and colon.

2. The weight of the distal third of the small intestine was significantly decreased in mice given diets B, C and D (P< 0·001). The length of the colon was significantly decreased in the mice given diets B (P< 0·001), C (P< 0·01) and D (P< 0·05); however, the weight of the colon was only decreased in the mice given diet B or diet C (P< 0·001).

Similar changes were noted in the weights of the intestinal muscle and serosa layers; however, no such changes were noted in the weight or DNA content of the mucosa.

3. No changes were observed in the crypt cell production rate in the small intestine, apart from an increase in the mid-region (P< 0·01) of mice given diet C, which was associated with a similar increase in the mucosal content of DNA.

Crypt-cell production was significantly decreased (P< 0·01, 0·001) in the two sites of the colon studied in the mice given diets B or C, but the crypt-cell production rates were not significantly different from control levels at either site in the mice given diet D.

4. The length of the colonic crypts was significantly decreased (P< 0·05, 0·02) in mice given diets B and C, but not in those given diet D; total cell number showed a similar change (P< 0·01, 0·05).

The correlation coefficient between the length of the colonic crypts and absolute cell number was 0·513.

5. The conclusion of the present study was that dietary fibre (cellulose), but not inert bulk (kaolin), prevents mucosal atrophy of the colon of mice given a fibre-free diet, and that many of the observed changes in intestinal weight are due to reduction in the bulk of the muscle layer.

Can elemental diets reduce the intestinal toxicity of 5-fluorouracil?

In order to test the hypothesis that elemental diets protect the intestinal mucosa against 5-fluorouracil toxicity, we have estimated water absorption, cytoplasmic peptide hydrolase activities, and mucosal DNA contents in isolated intestines from rats fed on one of three elemental diets or a standard diet and injected with 5-fluorouracil. Water absorption rates were significantly increased when rats, not injected with 5-fluorouracil, were fed on Flexical or Vivonex-HN. However, water absorption was severely impaired 3 days after administration of 5-fluorouracil and none of the elemental diets alleviated this impairment of absorption. Cytoplasmic peptide hydrolase activities and mucosal DNA contents were also severely decreased after 5-fluorouracil injection, the changes observed being independent of the diet. Also, none of the elemental diets reduced the body weight losses observed after 5-fluorouracil administration. Although the effects of the sodium salt of 5-fluorouracil on body weight and food intakes were much less severe than those of the Tris salt the two salts had identical effects on intestinal absorption even when an elemental diet was used. Although there was a smaller incidence of diarrhea after 5-fluorouracil administration when the rats had been fed on one of the elemental diets, diet B, the results do not support the suggestion that elemental diets might reduce the intestinal toxicity of 5-fluorouracil.