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PubMed1991

Small cell carcinomas of the large intestine.

The authors studied the clinical and pathologic features of 38 small cell carcinomas of the large intestine. Most were located in the right colon. Overlying adenomas were present in 45% and squamous differentiation in 21% of tumors. Endocrine differentiation was present in all tumors by at least one method; neuron-specific enolase, dense-core granules, and synaptophysin were present in most cases. Seventy-one percent of tumors metastasized to the liver; 64% of patients were dead at five months follow-up. Twenty-one poorly differentiated adenocarcinomas and undifferentiated carcinomas of the large intestine accessioned during the same period showed less endocrine (7 of 21) and squamous differentiation (1 of 15) and fewer liver metastases (4 of 15) than did small cell carcinomas. Among all 59 tumors studied, small cell histologic characteristics correlated better with liver involvement than did endocrine markers or other histologic features. Small cell carcinomas of the large intestine are aggressive tumors with a propensity for early liver involvement. Although there is a spectrum of squamous, endocrine, and glandular features in large bowel tumors of low degrees of differentiation, the identification of a small cell component appears to be most clinically relevant.

Adenocarcinoma↗
PubMed1993

Oat bran but not a beta-glucan-enriched oat fraction enhances butyrate production in the large intestine of pigs.

Digestibility of polysaccharides and other macronutrients and the metabolic response of the microflora in the large intestine to a low dietary fiber wheat flour diet and three enriched diets with equal amounts of added dietary fiber (oat bran, a beta-glucan-enriched oat fraction and insoluble oat residues) were studied in ileal-cannulated pigs. The digestibility of starch was high in the small intestine (98-100%). At this site of the gastrointestinal tract there was also a significant degradation of mixed linked beta (1 --> 3; 1 --> 4)-D-glucan (beta-glucan) (45-54%), whereas arabinoxylan was quantitatively recovered in ileal effluent. Type and amount of polysaccharides passing the ileal-cecal junction had little effect of the density of microorganism in the large intestine (approximately 10(10) viable counts/g digesta) but did have a high impact on the activity of the flora in colon as measured by the concentration of ATP in digesta. The relative proportion of butyrate in the short-chain fatty acids in the luminal contents of the large intestine was 6.6-8.4% when the low dietary fiber wheat flour diet was fed. However, when either oat bran or insoluble residues were included in the diet, the level was raised to 9.3-11.2%. No effect was seen after the addition of the beta-glucan-enriched fraction. This study showed that arabinoxylan and not beta-glucan in the cell walls of oat bran was responsible for the enhanced butyrate production of oat bran.

Animals↗
PubMed1995

Cell apical surface area in enterocytes from chicken small and large intestine during development.

The absorptive surface of epithelial cells from chicken small and large intestine was studied at the day of hatch (1 d group) and at 2 and 6 wk after hatch. The segments considered were duodenum, jejunum, ileum, cecum (proximal, medial, and distal regions), and rectum. The length, diameter, and density of microvilli as well as cell apical diameter were measured in tip-villous enterocytes by transmission electron microscopy. The results obtained showed that during development: 1) microvillus length remained constant in duodenum and jejunum and decreased in the other segments; 2) microvillus diameter increased only in the jejunum and the rectum; 3) microvillus density increased in duodenum, ileum, distal cecum, and rectum (especially from 1 d to 2 wk) and did not change in the other segments; 4) cell apical diameter did not change; 5) apical surface area increased both in the duodenum (2nd to 6th wk) and in the jejunum (1 d to 2 wk) but did not change in the ileum. In the proximal-medial cecum and in the rectum there was a decrease in apical surface, whereas no changes were observed in distal cecum. Results indicated that microvillus length and density are the variables that best explain the changes observed in apical surface that occurred during development.

Animals↗
PubMed1999

Regional differences in the sympathetic innervation of the guinea pig large intestine by neuropeptide Y- and tyrosine hydroxylase-immunoreactive nerves of divergent extrinsic origin.

Region-specific patterns of nerves with immunoreactivity to neuropeptide Y (NPY) have been described previously in the submucous plexus of guinea pig large intestine. Because these may have functional significance, the possibility of similar, characteristic variations of NPY-like immunoreactivity (NPY-ir) in the myenteric plexus was explored. Regional differences were found in the occurrence and pattern of distribution of NPY-ir in the myenteric plexus of the guinea pig large intestine. NPY-ir was present rarely within neuron somata in any region of the large intestine, and NPY-ir nerve fibers were present only within the distal large intestine, increasing progressively in density from the distal spiral to the rectum. Lesion of the colonic nerves, but not the hypogastric, intermesenteric, or lumbar splanchnic nerves, resulted in a loss of NPY-ir in the distal spiral and transverse colon but not in the descending colon or rectum. Ring myotomies in the descending colon resulted in a loss of NPY-ir proximal to the lesion. Dual-labeling immunohistochemical studies revealed that the NPY-ir nerve fibers rarely contained immunoreactivity for tyrosine hydroxylase (TH). Extrinsic nerve lesions resulted in an unequivocal reduction in NPY-ir in intraganglionic fibers of the submucosal plexuses of the transverse colon and a partial loss in the distal spiral and descending colon: the rectum was unaffected; in only a minority of guinea pigs, however, was any decrease in the NPY-ir innervation of submucosal blood vessels detected. The principal projections of NPY-ir nerves were from and through the inferior mesenteric ganglion; however, NPY-ir was not colocalized with TH-ir. It is proposed that nonnoradrenergic, NPY-containing neurons located in the inferior mesenteric ganglion project through the colonic nerves and that these proximally directed fibers innervate the transverse colon and the distal spiral. Nonnoradrenergic, NPY-ir neurons lying in the pelvic ganglia or sacral sympathetic chain may make an important contribution to the innervation of the myenteric plexus of the rectum and the descending colon.

Animals↗
PubMed2002

Effects of an abrupt increase of starch-rich concentrates in the diet of dairy cows on concentrations of volatile fatty acids in the rumen and large intestine and on myoelectric activity of the spiral colon.

OBJECTIVES: To describe the effects of an abrupt increase of concentrates in the diet of dairy cows on myoelectric activity of the spiral colon and on fermentation patterns in the rumen and large intestine. ANIMALS: 6 healthy lactating Simmental x Red-Holstein cows. PROCEDURES: The diet of 6 cows implanted with bipolar electrodes in the spiral colon was changed from hay only to a ration of 50% hay:50% starch-rich concentrates during a period of 60 hours. Myoelectric activity of the spiral colon, concentrations of absolute and undissociated volatile fatty acids (VFA), and pH of ruminal and large intestinal contents were monitored before, during, and after the dietary change. RESULTS: Significant changes in patterns of myoelectric activity of the spiral colon were restricted to phases III and IV of the bovine migrating myoelectric complex and to propagation velocity. Significant alterations were not observed in pH or VFA concentrations in ruminal fluid, but pH decreased and VFA concentrations increased significantly in fecal specimens after the change of diet. CONCLUSIONS AND CLINICAL RELEVANCE: Although rumen fluid is of limited value for measurement of certain indicators of fermentation, fecal samples can be used for measurement of pH and VFA concentrations, which serve as indicators of fermentation patterns in the large intestine. Increased concentrations of VFA and low pH in large intestinal digesta have a minimal influence on myoelectric activity of the spiral colon. Increased luminal VFA concentrations are unlikely to play an important role in the etiopathogenesis of motility disorders of the large intestine in cattle.

Animal Feed↗
PubMed1994

Role of leuX in Escherichia coli colonization of the streptomycin-treated mouse large intestine.

Escherichia coli F-18, a normal human fecal isolate, is an excellent colonizer of the streptomycin-treated mouse large intestine. E. coli F-18 Col-, a derivative of E. coli F-18 that no longer makes the E. coli F-18 colicin, colonizes the mouse large intestine as well as E. coli F-18 when fed alone, but is eliminated when fed together with E. coli F-18. Recently, a random bank of E. coli F-18 DNA was transformed into E. coli F-18 Col-, the resultant population was fed to streptomycin-treated mice, and the intestine was used to select the best colonizer. In this fashion, a 6.5 kb E. coli F-18 DNA fragment was isolated. This fragment was shown to enhance E. coli F-18 Col- mouse large intestinal colonizing ability and survival during stationary phase in intestinal mucus in vitro, as well as stimulate the synthesis of type-1 fimbriae. Here, we present evidence that the gene responsible for the enhanced E. coli F-18 Col- colonizing ability and survival during stationary phase in vitro is leuX. This gene encodes a rare leucine tRNA specific for the UUG codon. In addition, we show that the presence of a functional leuX gene is necessary for E. coli K-12 intestinal colonization and for survival in stationary phase.

Animals↗