Impact of nutritional status on DRG length of stay

A prospective audit of 100 admissions to a general medical unit was performed to determine the relationship of the initial nutritional status of the patients to the actual length of stay and hospital charges. These data then were compared with the allowed length of stay and estimated reimbursement under the prospective payment system of diagnosis-related groups (DRGs). Forty-five percent of the malnourished patients were hospitalized longer than that allowed under DRGs, compared to 30% for normal patients and 37% in the borderline group. The average length of stay was 15.6 +/- 2.2 days in the malnourished group compared to approximately 10 days in the other two groups (p less than 0.01). Although the estimated base DRG reimbursement was similar in all three groups ($4352-$5124), the actual hospital charges were significantly greater in the malnourished ($16,691 +/- 4389) and borderline ($14,118 +/- 4962) groups compared to normals ($7692 +/- 687), (p less than 0.01). The DRG system will have an adverse financial impact in the care of malnourished patients. It is suggested that early recognition of malnutrition and aggressive treatment may lead to a decrease in the length of stay and cost deficit incurred by malnourished patients.

Small-bowel resection. Oral intake is the stimulus for hyperplasia

Small-bowel resection leads to hyperplasia of the residual small intestine, However, the factors initiating small-bowel hyperplasia are not clearly understood, although oral intake either by direct contact with the small bowel or via hormonal or neurovascular factors has been suggested as the major stimulus. In order to determine whether oral intake is an obligatory prerequisite for small-intestinal hyperplasia, we compared rats one week after undergoing a 70-cm proximal intestinal resection with sham-operated animals. Resected, orally fed rats demonstrated small-intestinal hyperplasia, whereas resected and sham-operated intravenously alimented rats did not. There were no differences in gut weight, mucosal weight, mucosal protein, or DNA between resected or sham-operated intravenously alimented rats. These data provide direct experimental proof that oral intake is a necessary stimulus for small-intestinal hyperplasia after resection.

Intravenous metronidazole for the treatment of Clostridium difficile colitis

PURPOSE

Severe Clostridium difficile colitis may produce abdominal distention and ileus, precluding oral antibiotic therapy. Stimulated by several case reports in which intravenous metronidazole was used, we reviewed our experience.

METHODS

Using pharmacy and microbiology laboratory records, we retrospectively identified patients with C. difficile colitis who received intravenous metronidazole as initial monotherapy. To be included, patients had to fulfill the following criteria: 1) at least six doses (equivalent to two days of therapy) of intravenous metronidazole were administered, 2) no other potential cause for colitis was found, and 3) the diagnosis of C. difficile colitis was firmly established. For eligible patients, five clinical parameters were assessed before and after intravenous metronidazole.

RESULTS

Our patient group (n = 10) received an average of 13.7 (range, 6-24) doses of intravenous metronidazole as initial therapy for C. difficile colitis. All received a dose of 500 mg three times daily. The majority of patients with vomiting, fever, and/or abdominal pain present at the beginning of therapy had resolution with intravenous metronidazole. Only one patient developed a symptom (vomiting) while on therapy; however, this eventually resolved when oral metronidazole was instituted. No patient required colectomy for refractory colitis or developed toxic megacolon. No patient, including those on prolonged courses, developed toxicity related to intravenous metronidazole such as peripheral neuropathy.

CONCLUSIONS

Intravenous metronidazole may be effective therapy in patients with C. difficile colitis. A randomized, prospective study appears warranted.

Serum albumin is predictive of 30-day survival after percutaneous endoscopic gastrostomy

BACKGROUND

Percutaneous endoscopic gastrostomy (PEG) tubes have been used since 1980 in patients who require prolonged enteral feeding.

PURPOSE

To identify factors associated with poor survival (defined as survival < 30 days) post-PEG.

METHODS

We assessed a cohort of 64 patients consecutively referred for a percutaneous endoscopic gastrostomy tube in a single, tertiary care hospital. Prior to PEG tube placement, we evaluated relevant clinical variables in each patient to determine their effect on 30-day mortality.

RESULTS

Of the cohort, 43 of 64 (67.2%) survived at least 30 days after tube placement. One death was attributable to tube placement. Bivariate analyses showed that 30-day survival correlated directly with serum albumin (r = .253; p = .049) and inversely with creatinine (r = -0.255; p = .042). Using multivariable logistic regression analysis, only albumin was identified as an independent predictor of 30-day survival (p = .044). Eighty-three percent of patients with a serum albumin > or = 3.0 g/dL survived 30 days compared with 58% with an albumin < 3.0, a difference of 25% (95% CI, -2% to 54%; p = .07).

CONCLUSIONS

In conclusion, serum albumin appears to be a predictor of early survival in individuals undergoing percutaneous endoscopic gastrostomy tube placement.

Prospective, randomized study of diagnosis and outcome in acute upper-gastrointestinal bleeding: endoscopy versus conventional radiography

Sixty patients with mild to moderate upper-gastrointestinal bleeding were admitted to a prospective, controlled study of diagnosis and management, and were randomized to endoscopy or upper-gastrointestinal (UGI) barium series as the initial study. Definitive localization of the source of bleeding was made initially in 69% of the endoscopy group and 21% of the UGI group (P less than 0.0005). Of 54 patients undergoing both studies, endoscopy was definitive in 67% and UGI series in 22%. Thus, endoscopy also made more diagnoses when used as the second study (P less than .01). The use of endoscopy as the initial procedure led to significantly more rapid diagnosis than with UGI series. However, there were no significant differences between the two groups in clinical outcome. Endoscopy is the initial diagnostic procedure of choice in patients with mild to moderate upper-gastrointestinal bleeding because it enables detection of superficial bleeding lesions and has significantly increased the speed of diagnosis.

Effect of short-chain fatty acids on colonic function and structure

Short-chain fatty acids (SCFA), fermentation products of fiber, are believed to play a role in intestinal adaptation. Although the administration of fiber or the infusion of SCFA has been shown to cause colonic growth, studies have been done primarily in enterally fed animals. In addition, the effects of SCFA on absorptive function have not been determined. Adult male rats were maintained on total parenteral nutrition (TPN) and, in addition, received either 150 mmol/L of saline or 150 mmol/L of SCFA mixture (60:25:15, acetate:propionate:butyrate) into the proximal colon. One week later, the in vivo absorption of water, electrolytes, and 20 mmol/L of butyrate was measured. After the rats were killed, parameters of colonic mass were determined. SCFA infusion into the colon had no significant effect on absorptive function. However, significantly greater mucosal height (p less than .01) and mucosal DNA (p less than .05), were observed. Although SCFA has a modest effect on colonic structure, they do not influence absorptive function in TPN rats.

The medical and financial costs associated with termination of a nutrition support nurse

BACKGROUND

Cost-containment pressures have adversely affected hospital nutrition support team staffing. We determined the effect of termination of a nutrition support nurse responsible for patients receiving total parenteral nutrition (TPN) on quality assurance and financial indicators.

METHODS

A retrospective review of all 1,093 patients receiving TPN from fiscal year (FY) 1992 through FY 1998 in a tertiary care community hospital. We documented the changes in care during years when the nutrition support nurse position was staffed, terminated, and restored. Indicators studied included inappropriate TPN, central venous line sepsis, TPN wastage, and estimates of preventable costs.

RESULTS

When the nurse was present, 8.6% of TPN patients had a functional gastrointestinal (GI) tract and inappropriately received TPN compared with 12.1% when the nurse was absent, a risk difference of 3.5% points (95% confidence interval [CI], -.06 to 8.3; p = .069). Risk of TPN-associated line sepsis increased from 8.8% of patients when the nurse was present to 13.2% when the nurse was absent, a difference of 4.4% points (95% CI, 0.06 to 9.2; p = .028). In the absence of the nurse, 26.3% of TPN patients had preventable charges vs 17.5% when the nurse was present (p < .0001). Total preventable charges were higher in the years without a nurse (p < .003). Total preventable costs increased by $38,148 to $194,285 (depending on the estimate for sepsis) in the year after termination. Reinstatement of the nurse resulted in a decrease in costs between $34,485 and $156,654.

CONCLUSIONS

Adequate staffing of a nutrition support team reduced inappropriate TPN and complications of TPN. Financial savings of the same order of magnitude as the nurse's compensation accompany substantial decreases in patient morbidity.

Nutrition support team recommendations can reduce hospital costs

Providing nutrition support may be costly to hospitals under the prospective payment system. A nutrition support team, however, can be effective in controlling costs. To demonstrate the importance of the nutrition support team and to quantify the potential cost savings that can be achieved, a retrospective review of the effect of our team on hospital costs was conducted for the 12-month period of October 1989 to September 1990. The team supervises but does not regulate the use of total parenteral nutrition (TPN). During this time period, 176 patients received TPN. In 14 patients, the use of TPN was inappropriate, representing $65,349 in excess costs. After the cost of providing enteral nutrition to these patients (estimated at $2,430) was deducted, a net loss of $62,919 occurred. Nutrition support team action saved an additional $45,186 in hospital charges when recommendations to discontinue TPN were eventually heeded. Nutrition support team approval before TPN is initiated would achieve cost savings.

A model for the reaction pathways of the K+-dependent phosphatase activity of the (Na+ + K+)-dependent ATPase

(Na+ + K+)-dependent ATPase preparations from rat brain, dog kidney, and human red blood cells also catalyze a K+ -dependent phosphatase reaction. K+ activation and Na+ inhibition of this reaction are described quantitatively by a model featuring isomerization between E1 and E2 enzyme conformations with activity proportional to E2K concentration: (formula; see text) Differences between the three preparations in K0.5 for K+ activation can then be accounted for by differences in equilibria between E1K and E2K with dissociation constants identical. Similarly, reductions in K0.5 produced by dimethyl sulfoxide are attributable to shifts in equilibria toward E2 conformations. Na+ stimulation of K+ -dependent phosphatase activity of brain and red blood cell preparations, demonstrable with KCl under 1 mM, can be accounted for by including a supplementary pathway proportional to E1Na but dependent also on K+ activation through high-affinity sites. With inside-out red blood cell vesicles, K+ activation in the absence of Na+ is mediated through sites oriented toward the cytoplasm, while in the presence of Na+ high-affinity K+ -sites are oriented extracellularly, as are those of the (Na+ + K+)-dependent ATPase reaction. Dimethyl sulfoxide accentuated Na+ -stimulated K+ -dependent phosphatase activity in all three preparations, attributable to shifts from the E1P to E2P conformation, with the latter bearing the high-affinity, extracellularly oriented K+ -sites of the Na+ -stimulated pathway.

Assessment of resolution by half distance values for tritium and radioiodine in electron microscopic radioautographs using Ilford L4 emulsion developed by "solution physical" or D-19b methods

Half distance values for electron microscopic (EM) radioautographs with the isotopes 3H and 125I were determined using Ilford L4 emulsion processed with either fine grain, solution physical development, or filamentous grain, chemical development with D-19b. 3H- and 125I-line sources, obtained by cutting perpendicular sections from sections of 3H-labeled methacrylate or 125I-labeled thyroid glands, were processed for EM radioautography. The distribution of silver grains around a line source was determined by measuring their distance from the source in photographs of EM radioautographs. The number of silver grains per unit distance from the line source was plotted on graphs and half distance values were calculated. With solution physical development, the half distance value was 74 nm for 3H and 80 nm for 125I; whereas with D-19 b development it was 187 nm for 3H and 157 nm for 125I. Since solution physical development produced a reduction of about 50% in the half distance values for both isotopes, it is concluded that the production of fine grain by this method provides better resolution for EM radioautography than filamentous grain development with D-19b.

Delayed esophageal perforation after pneumatic dilatation for the treatment of achalasia

Two cases of delayed esophageal perforation following a pneumatic dilatation for the treatment of achalasia are presented. Esophagrams obtained immediately after pneumatic dilatation failed to reveal a perforation. Increasing symptoms prompted repeat contrast studies, at which time an esophageal perforation was demonstrated. The occurrence of delayed esophageal perforation after pneumatic intrumentation is emphasized. An ischemic etiology for this delayed perforation is postulated.

Impact of a quality assurance program on gastrointestinal endoscopy

The impact of a quality assurance committee on documentation and use of gastrointestinal endoscopy was assessed. The committee, fulfilling Joint Commission on Accreditation of Healthcare Organizations criteria, performed retrospective (1984-1985) and prospective (1986-1988) reviews of all endoscopies. Criteria were developed from American College of Physicians and American Society for Gastrointestinal Endoscopy guidelines. All reviews of procedures that were questioned were returned to physicians for clarification. After reconsideration of the response, procedures were judged either justified or unjustified. There has been significant improvement in the quality of endoscopy reporting and documentation. The rate of questioned procedures decreased from 21.6% (95% confidence interval (CI), 20.1-23.1) in 1984-1985 to 9.2% (95% CI, 7.9-10.4) (P less than 0.01) in 1988. Improvement in use was reflected in the significant decrease in the rate of unjustified procedures from 8.2% (95% CI, 7.2-9.2) in 1984-1985 to 1.5% (95% CI, 1.0-2.0) (P less than 0.01) in 1988. Most importantly, this process curtailed the previously noted 10% annual increase in the number of endoscopic procedures (P less than 0.01).

Impact of age, sex, race, and functional complaints on hydrogen (H2) production

In order to evaluate factors that may influence H2 generation, the effects of age, sex, race, and functional complaints on breath H2 were studied in 62 subjects. These included 34 young hospital employees, 17 healthy ambulatory elderly subjects, and 11 patients with functional bowel disease. The ability to produce H2 was defined by an increase in breath H2 to greater than 20 parts per million within 4 hr of ingesting 10 g of the nonabsorbable sugar lactulose. Overall, 21% of subjects were nonproducers, and the incidence of nonproduction did not vary among the groups. The elderly subjects had significantly greater breath H2 concentrations than the younger subjects at 150 minutes (P less than 0.05). Sex, race, and functional complaints did not influence H2 production. These findings indicate that patient's age and potential inability to make H2 need to be considered in the routine interpretation of H2 breath tests.

Intestinal triglycerides are derived from both endogenous and exogenous sources

Although studies have indicated that the small intestine is capable of utilizing endogenous substrates for triglyceride synthesis in the absence of dietary lipid, the importance of the endogenous contribution to total intestinal triglyceride production during absorption has not yet been defined. In this study we have examined the quantitative contribution of endogenous triglyceride production during different luminal lipid loads. By use of a mesenteric lymph fistula rat model with total parenteral nutritional support, mesenteric lymphatic triglyceride transport was investigated. Our results indicate that, during absorption, a substantial fraction (greater than 50%) of total triglyceride is derived from endogenous sources. Increased luminal fatty acid loads lead to an increase in both endogenous and exogenous triglyceride production. Incorporation of luminally infused oleic acid into triglyceride carried by chylomicrons is dependent on the luminal fatty acid load, while incorporation of oleic acid into very low-density lipoprotein (VLDL) triglyceride is saturable. We conclude that both chylomicron and VLDL are involved in transporting triglyceride derived from both endogenous and exogenous sources. The different patterns in the partition of endogenous and exogenous triglyceride into chylomicrons and VLDL suggest that these two lipid-carrying lipoproteins are probably packaged differently in the small intestine.

Feeding tube-induced pneumothorax

A case of accidental bronchial perforation by the metal stylet of a silastic feeding tube is reported. The misplacement of the feeding tube resulted in a pneumothorax. This is a previously unreported complication of enteral feeding in adults. Pulmonary complications of enteral feeding and recommendations for prevention of these complications are discussed.

Luminal and metabolic regulation of jejunal amino acid absorption in the rat

Studies were carried out to determine the role of luminal amino acids and metabolic balance in in vivo amino acid absorption. Previous in vitro studies have shown that adaptation of amino acid transport is a complex phenomenon. In the first series of experiments, parenterally nourished rats received a 7-day jejunal infusion of either 3% aspartic acid, glutamine, lysine, valine, or mixed amino acids. A single-pass perfusion was performed to determine the effects of infusates on 5 mM valine, aspartic acid, and lysine absorption. Compared with controls receiving luminal saline, prior glutamine infusion increased valine absorption; prior valine, glutamine, and aspartic acid infusion significantly increased aspartic acid absorption; and prior valine and lysine infusion significantly increased lysine absorption. The mixed amino acid solution had no effect. The effects of metabolic balance were examined by comparing fasted rats with parenterally fed and orally fed rats. Within 24 h fasting significantly increased valine and aspartic acid absorption, despite a significant decrease in intestinal mass.

Phase I clinical evaluation of a new murine monoclonal antibody (Mu-9) against colon-specific antigen-p for targeting gastrointestinal carcinomas

BACKGROUND

Colon-specific antigen-p is a tumor-associated antigen present in approximately 60% of colorectal cancers. Preclinical studies have shown that the murine monoclonal antibody Mu-9 has excellent tumor-targeting abilities; therefore, clinical studies were initiated.

METHODS

The immunoglobulin G and F(ab')2 were radiolabeled with 131I and administered to 13 and 12 patients, respectively, with advanced gastrointestinal cancer (colon, rectal, and pancreatic) for radioimmunodetection or radioimmunotherapy.

RESULTS

Even in patients with highly elevated carcinoembryonic antigen levels, only one patient showed appreciable complexation of the labeled antibody, suggesting the epitope may not be highly expressed in the blood. Fifty percent of 131I-Mu-9 immunoglobulin G was cleared from the blood within 41 +/- 13 hours, while it took only 19 +/- 8 hours for the same amount of 131I-F(ab')2 to be cleared from the blood. Lesion detection in the abdomen, liver, and pelvis was greater than 90% for either the immunoglobulin G or F(ab')2. The dose absorbed by the normal organs, except the kidneys, was two- to threefold less for the F(ab')2 than for the whole immunoglobulin G. The dose to the kidneys was similar for both forms of immunoglobulin. The average tumor dose for 131I-Mu-9 immunoglobulin G was 13.9 +/- 11.0 cGy/mCi, and for 131I-F(ab')2 was 4.9 +/- 2.9. Tumor/red marrow dose ratios for the whole immunoglobulin G were 4.3 +/- 3.0, compared to 3.3 +/- 1.9 for the F(ab')2, suggesting the therapeutic window for the two forms of immunoglobulin may be similar. Eight of nine patients given the whole immunoglobulin G developed highly elevated levels of human anti-mouse antibody, whereas lower values were observed in five of seven patients given the F(ab')2.

CONCLUSIONS

These initial results support the need for further evaluation of Mu-9 immunoglobulin G and F(ab')2 for targeting gastrointestinal cancer for radioimmunotherapy.

How gastroenterologists inform patients of results after lower endoscopy

OBJECTIVE

Little is known about how gastroenterologists communicate endoscopic findings and biopsy results to their patients. We sought to determine the factors that may influence this behavior.

METHODS

A survey questionnaire was developed and mailed to the 80 members of the Delaware Valley Society for GI Endoscopy. Information was obtained on the demographic characteristics and responses to six case vignettes prepared to examine communication patterns. We determined possible influences of conscious sedation and the benignity or severity of findings on communication practices.

RESULTS

Sixty-one surveys (76%) were completed and analyzed. Endoscopists immediately inform patients of normal results. For abnormal results, 92% would immediately inform nonsedated patients versus 79% that would inform sedated patients (p < 0.008). Analysis of responses to the case vignettes indicated that 82% of endoscopists would immediately reassure the patient about a benign appearing (< 1 cm) polyp, but only 70% would do so for a polyp > 2 cm (p < 0.01). In contrast, when presented with a frank malignancy, 94% would inform the patient. Eighty-four percent of endoscopists would telephone results of a benign pathology report, but only 34% would telephone report a dysplastic lesion (p < 0.001). There was no correlation between the response rate and various demographic parameters such as physician age, type of, or length of time in practice.

CONCLUSIONS

Gastroenterologists usually report normal findings immediately, but are less likely to do so after use of sedation or encountering abnormal findings. Most of those surveyed would use the telephone to communicate abnormal findings.

Quantitative immunocytochemistry by digital image analysis: application to toxicologic pathology

Recent advances in immunocytochemical techniques allow the localization of specific antigens in tissue sections. The work reported here attempts to evaluate the application of antibody-labeled, disease-related protein, followed by microscopy and computerized image analysis. Using an experimental anti-tumor, polyclonal antibody (anti-oncomodulin) as a model, various tissues were prepared for light microscope immunocytochemistry. Sections were incubated with primary antibody, then biotinylated secondary antibody. This was followed by incubation with avidin-biotin-peroxidase (ABC method). Marker was visualized by the presence of precipitated diaminobenzidine. Samples were evaluated using a Zeiss/Kontron IBAS I & II semi-automatic digital image analysis system. Statistical analyses were performed on output data. Results demonstrated the localization and determined optical density of immunolabel. Statistical comparisons showed significant differences between control and experimental sections. The practical application of these combined techniques provides the toxicologic pathologist with a powerful tool for accurate and objective determination of the location and relative amount of selected proteins in normal and abnormal tissues.

Comparison of different caloric substrates on intestinal adaptation in the rat

We compared the relative efficacy of medium- and long-chain triglycerides and dextrose on intestinal adaptation. Parenterally nourished rats received an isocaloric luminal infusion of one of these three substrates for 1 wk into either the jejunum or the ileum. Intestinal mass (mucosal weight and protein content) as well as the in vivo absorption of 5 mM glucose, valine, and aspartic acid were measured. In the jejunum, long-chain triglycerides were the most trophic, whereas in the ileum, long-chain triglycerides and dextrose were equally effective, but significantly more trophic than medium-chain triglycerides. In general, absorptive function was better maintained by dextrose and medium-chain triglycerides than long-chain triglycerides in the jejunum or by dextrose in the ileum. These data demonstrate that the jejunum and ileum respond differently to caloric substrates. Medium-chain triglycerides do not appear to have a clear superiority to long-chain triglycerides or dextrose in producing intestinal adaptation.

Effect of toal parenteral nutrition on gastric acid secretion

While total parenteral nutrition is widely used, its effects on gastrointestinal function are not well understood. We measured acid secretion in 11 patients during total parenteral nutrition. Five of these patients were retested at least one month after resuming oral intake. Total parenteral nutrition significantly stimulated acid secretion compared to saline infusion (5.5 +/- 2.0 vs 1.8 +/- 0.6 mEq H+/hr, P less than 0.001) (mean +/- SEM), especially in those patients who are hypersecretors. There was no difference in pentagastrin-stimulated maximal acid output during TPN or saline infusion. Basal and pentagastrin-stimulated acid secretion were similar during and after a course of total parenteral nutrition, suggesting that gastric atrophy did not occur during total parenteral nutrition therapy.

Nonspecific adaptation of jejunal amino acid uptake in the rat

Luminal nutrients are a major effector of intestinal adaptation. Amino acids are trophic to the intestine, but their role in regulating amino acid transport is not well documented. The presence of several distinct amino acid transport systems raises the question of whether adaptation is class-specific. Studies were carried out in parenterally nourished rats receiving a 7-day jejunal infusion of a 3% solution of either aminoisobutyric acid, aspartic acid, glutamine, histidine, lysine, or valine. While all amino acids were trophic to the intestine, their effects on the in vitro uptake of 0.1, 1.0 and 10.0 mM aspartic acid, lysine, and valine (representative acid, basic, and neutral amino acids) were variable and nonspecific. Compared to controls receiving either total parenteral nutrition alone or total parenteral nutrition plus luminal saline, prior lysine and aspartic acid infusion significantly increased in vitro uptake of all three amino acids tested, whereas valine had little effect on transport. No effect on transport was seen with glutamine (actively metabolized by the intestine as is aspartic acid), aminoisobutyric acid (a nonmetabolizable amino acid congener), or histidine (the most trophic amino acid). In conclusion, while individual amino acids cause an adaptation of amino acid uptake, the effects are nonspecific and independent of their metabolic or trophic potential.

Effect of fiber and its fermentation on colonic adaptation after cecal resection in the rat

BACKGROUND

The role of fiber in postresection adaptation is poorly understood. We examined the significance of short-chain fatty acids produced by intracolonic fiber fermentation during colonic adaptation.

METHODS

Rats underwent one of three surgeries: control laparotomy, cecal resection, or cecal resection with placement of perfusion catheter. Rats of each surgical group were randomly assigned to receive treatment regimens of standard fiber diet (with or without fermentation-suppressing antibiotics), fiber-free diet, or diet plus intracolonic perfusion of short-chain fatty acids. Adaptation parameters of mucosal weight, mucosal DNA and protein content, water absorption, and butyrate absorption were measured.

RESULTS

Compared with controls, postresection rats that were fed fiber had 65% greater basal and 112% greater butyrate-stimulated water absorption as well as 140% greater butyrate absorption. Fiber-fed rats exhibited significantly greater colonic weight and colonic mucosal protein after cecal resection. These changes were absent in postresection rats fed a fiber-free diet. Inhibition of fermentation by neomycin and metronidazole added to a standard fiber diet also prevented postresection adaptation. All adaptive changes were restored when the cecal-resection rats that were fed the fiber diet with antibiotics received an intracolonic infusion of short-chain fatty acids. Adaptation did not occur when short-chain fatty acids were infused into colons of postresection rats that were fed a fiber-free diet.

CONCLUSIONS

Cecal resection leads to significant functional and structural changes in the adapting residual colon. Fermentation of dietary fiber by colonic flora to short-chain fatty acids is necessary, but it alone is not sufficient to mediate adaptation.

Effects of fiber-containing liquid diets on colonic structure and function in the rat

Dietary fiber plays a role in maintaining colonic structure and function. Recently, fiber-supplemented liquid diets containing primarily soy polysaccharide have been marketed. However, the effects of these diets on the colon, particularly absorptive function, are not well documented. We compared Jevity (containing 1.4% soy polysaccharide) to fiber-free Osmolite. In addition, we were interested in comparing the effects of soy polysaccharide to that of pectin, which has previously been shown to facilitate adaptation. A 1% pectin-supplemented rat liquid diet was compared to the liquid diet alone. After 2 weeks of dietary treatment, rats were anesthetized and in vivo colonic absorption measured. Both Jevity and the pectin-containing diets led to a significantly greater (p less than 0.01) basal and butyrate stimulated water absorption as well as 20 mM butyrate absorption compared to their fiber-free fed controls. After perfusion, rats were killed and parameters of colonic mass measured including mucosal weight, protein, and DNA. The fiber-containing diets produced a modest, nonsignificantly greater colonic mass compared to their fiber-free controls. A commercial diet containing soy polysaccharide seems to be equally effective as pectin in maintaining colonic absorptive function.