The effects of biofeedback on rectal sensation and distal colonic motility in patients with disorders of rectal evacuation: evidence of an inhibitory rectocolonic reflex in humans?

OBJECTIVE: Abnormalities of descending colon motility reported in a subset of patients with rectal evacuation disorders are consistent with a rectocolonic inhibitory reflex. Our aims were to evaluate distal colon motor function and rectal sensation in such patients and assess effects of biofeedback (BF) training on these functions. METHODS: Seven patients (five women, two men; mean age 36 yr) with rectal evacuation disorders were studied before and after 10-days biofeedback training; six healthy volunteers (five women, one man; mean age 30 yr) were studied once. Colonic compliance, motility, sensation thresholds, and perception scores during standardized rectal distentions were measured using two barostat-manometry assemblies inserted into the cleansed colon with the aid of flexible sigmoidoscopy. RESULTS: Sigmoid compliance, fasting, and postprandial motility index, and perception thresholds were similar in controls and patients before and after biofeedback training. Postprandial sigmoid tone tended (p = 0.09) to be lower in patients than controls; after biofeedback, postprandial tone was comparable to that in controls. Rectal urgency scores at 24 mm Hg distention were greater in patients than in controls (p = 0.02 for both). After biofeedback, there were trends for lower perceptions of urgency to defecate (7.6 +/- 1.1 cm pre- vs 5.3 +/- 1.5 post-; p = 0.04) at 24 mm Hg; conversely, gas sensation at 12 mm Hg was higher (1.2 +/- 0.5 cm pre- vs 3.3 +/- 0.6 post-; p = 0.05). CONCLUSIONS: Normalization of rectal evacuation and postprandial sigmoid tone in patients with evacuation disorders by biofeedback training supports the presence of a rectocolonic inhibitory reflex. Effect of biofeedback on rectal sensation in these patients requires further study.

Dexpanthenol enemas in ulcerative colitis: a pilot study.

OBJECTIVE: To test the hypothesis that topical administration of pantothenic acid, a precursor of coenzyme A, might result in increased tissue levels of coenzyme A, improvement of fatty acid oxidation, and amelioration of ulcerative colitis. MATERIAL AND METHODS: In an open-label pilot study, three patients with active left-sided ulcerative colitis received nightly enemas that contained 1,000 mg of dexpanthenol for 4 weeks. Before and after the study, patients submitted stool specimens for short-chain fatty acid analysis and urine collections for measurement of pantothenic acid and dicarboxylic acids; they also underwent flexible sigmoidoscopy for procurement of biopsy specimens for histologic examination and measurement of colonic coenzyme A activity. A clinical disease activity index and histologic disease activity index were used to assess response. RESULTS: Despite increases in urinary pantothenic acid, no significant changes were found in colonic tissue coenzyme A concentrations, fecal short-chain fatty acid concentrations, or urinary dicarboxylic acid concentrations. Moreover, no significant changes in clinical or histologic disease activity were noted. Although stool frequency and rectal bleeding remained unchanged, all patients noted increased abdominal cramping, and one patient had an increased extent of disease. CONCLUSION: Topically administered dexpanthenol seems to be absorbed, but at the dose used in this study, it did not influence concentrations of colonic coenzyme A activity, fecal short-chain fatty acids, or clinical response in patients with active left-sided ulcerative colitis.

Olestra, a nondigestible, nonabsorbable fat. Effects on gastrointestinal and colonic transit.

Olestra, the name proposed for the mixture of hexa-, hepta- and octaesters of sucrose and long-chain fatty acids, is a nondigestible, nonabsorbable lipid with physical properties and taste that are similar to those of natural triglycerides. Our aim was to determine whether substitution with up to 30 g of olestra in a 45-g fat meal would alter gastric, small bowel, and colonic transit. Five groups, each of six healthy volunteers, ingested 800-kcal, 22-g protein meals containing a total of 45 g of lipid (N = 24) or 15 g of lipid (N = 6). Among those receiving the 45-g fat meal, 0, 7.5, 15 and 30 g of lipid were substituted with olestra (N = 6 per group). The 15-g fat meal consisted entirely of natural triglyceride. A dual gamma camera scintigraphic method was used to estimate gastric and small bowel transit (99mTc pellets in the meal) and colonic transit (111In pellets). The latter was achieved by the delayed release of 111In pellets from a capsule coated with a pH-sensitive polymer, methacrylate, that disintegrated in the terminal ileum. There were no differences in the gastric, small bowel, or colonic transits of any of the five equicaloric meals. Some individuals had a significantly greater 48-hr stool weight after ingesting 15 g of olestra, but stool weights of subjects consuming 7.5 g or 30 g of olestra did not differ from controls. We conclude that substitution with olestra of up to 30 g in a 45-g fat meal does not significantly alter gastrointestinal transit in healthy subjects.

Distribution of mesalamine enemas in patients with active distal ulcerative colitis.

Mesalamine (5-aminosalicylic acid), a topically administered anti-inflammatory agent, is effective treatment by enema for distal ulcerative colitis; it lacks many of the side effects of orally administered sulfasalazine. In this study, we determined the colonic distribution of a 60-ml mesalamine enema in eight patients (five women and three men, 18 to 48 years old) with active distal ulcerative colitis that ranged from 12 to 40 cm proximal to the anal verge. On 3 consecutive days, each patient self-administered a 4-g (60-ml) 5-aminosalicylic acid enema that contained 3.7 MBq of [99mTc]technetium-sulfur colloid. Anterior and posterior images were obtained at 0, 30, 60, 120, and 240 minutes. During the 4-hour study period, all patients retained the enemas. The enemas spread to the sigmoid region in 24 of 24 studies, to the splenic flexure region in 22 of 24, and to the transverse colon in 1 of 24. Most of the enema was retained in the sigmoid colon. Therefore, we conclude that a 60-ml enema, when administered as recommended clinically, routinely flows retrograde as far as the splenic flexure but rarely spreads beyond this point. These results support the use of intrarectally administered 5-aminosalicylic acid for segmental colitis of the descending colon.

Components of fiber bind iron in vitro.

Interactions among fiber, inorganic iron, and substances known to chelate iron were examined in vitro. Cellulose, neutral and acid fractions of lignin, psyllium mucilage, and pectin were incubated with 59Fe SO4 at various pH's, in various concentrations, and in the presence or absence of known chelators of iron including ascorbate, citrate, cysteine, fructose, and EDTA. Insoluble components of fiber were tested in a precipitation-centrifugation system, soluble components were tested by equilibrium dialysis. Lignins and psyllium mucilage had the greatest capacity to bind ferrous iron under conditions that approximated those of the proximal intestine postprandially; cellulose and pectin were less potent. Dissociation constants of binding were similar for several components, suggesting the existence of comparable binding sites in different components of fiber. Citrate and EDTA inhibited the binding of iron markedly but other chelators were much less effective. These reactions among fiber, inorganic iron, and other constituents of food may influence the bioavailability of dietary iron and the simple systems described here offer a means of dissecting interactions that are complex in vivo.

Components of fiber impair iron absorption in the dog.

We have demonstrated previously that semipurified components of fiber bind ferrous iron in vitro. The present studies examined the possibility that these same fibers would decrease absorption of iron by the canine small bowel. Healthy and anemic dogs were studied chronically. Two preparations were needed; soluble components of fiber were tested by continuous perfusion of a duodenojejunal segment of approximately 100 cm, insoluble components were tested in Thiry-Vella fistulae of jejunum (25 cm). The results confirm that, 1) anemic dogs absorb iron more efficiently than do healthy animals, and 2) that there is a slight, but significant, decrease in iron absorption during the 4 to 6 h of an acute experiment. To obviate problems of interpretation because of the latter point, all studies featured a control period, before and after, the test period. Lignin and psyllium mucilage were potent inhibitors of iron absorption, pectin less so, and cellulose was without effect in this system. The results in vivo correlate well with the binding of iron in vitro.

Ricinoleic acid causes secretion in autotransplanted (extrinsically denervated) canine jejunum.

To examine the role of extrinsic nerves and hormones in intestinal secretion of fluid, we studied the effect of ricinoleic acid on absorption by isolated, autotransplanted jejunal loops in four dogs. Compared to perfusion with control solution, the addition of ricinoleic acid caused reversible secretion of water and electrolytes and inhibition of glucose absorption, as previously described in the innervated intestine. In contrast, oral castor oil caused diarrhea but had no effect on absorption from the denervated loop. Thus, the secretory action of ricinoleic acid is maintained without the influence of extrinsic nerves; in addition, further support is added to the proposal that hormones do not mediate secretion in this model. These findings support a local mechanism for the secretion induced by ricinoleic acid.

Recovery of dietary iron and zinc from the proximal intestine of healthy man: studies of different meals and supplements.

The technique of marker perfusion of the upper gastrointestinal tract was used to measure intraluminal quantities of iron and zinc after test meals in healthy humans. Two different meals, one based on hamburger (with a predominance of heme iron, 7.5 mg/meal) and one based on cereal (containing inorganic iron; 1.4, 5.3, or 4.6 mg), were used. In addition, the luminal behavior of ferrous sulfate and hydrogen-reduced metallic iron (used as supplements to the cereal meal) were compared. Different meals also contained low (2.4 mg) or high (5.5 mg) amounts of zinc. The intubation techique allowed disappearance of metals from the duodenum and jejunum to be compared. The patterns of luminal flow were different for iron and zinc. Whereas iron was never recovered from the lumen at levels above those ingested in meals, zinc was recovered from the duodenum at levels greater than those ingested. These findings suggest that zinc, but little iron, is added to chyme in the upper gut during digesting and absorption. Bioavailability of different forms of iron, as judged by their luminal disappearance, were similar. Inorganic iron, ferrous sulfate, and hydrogen-reduced metallic iron were absorbed about as effectively as was heme iron. Iron disappeared preferentially from the duodenum but the site of zinc absorption appeared to be more distal.

Chronic diarrhea. A practical approach.

Many patients who present with chronic diarrhea are not found to have an important organic disease. Most will have "functional" diarrhea. The history, the physical examination and the initial laboratory tests should lead to a provisional diagnosis, with respect to the organic or functional origin, and the location of disease in the small or the large bowel. Specific tests are then done to define particular organic causes of which malabsorption, inflammatory bowel diseases, carcinoma of the large bowel, parasitic infections, and metabolic disorders are most common. Patients with suspected functional diarrhea should be investigated at least by stool analysis, proctosigmoidoscopy, and barium enema. Functional diarrhea is common and these patients are no less susceptible to severe disease than is the rest of the population.