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Results for “Colon, Descending”

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At least 73 records · Page 4Linked to original sources
PubMed2006

Expression of gamma-aminobutyric acid and glutamic acid decarboxylases in rat descending colon and their relation to epithelial differentiation.

OBJECTIVE: To detect the expression of gamma-aminobutyric acid (GABA) and glutamic acid decarboxylases (GADs; including two isoforms GAD65 and GAD67) in the epithelial growth zones of the descending colon in rats, and to investigate their relation to epithelial differentiation and proliferation. METHODS: The expression of GABA and GADs in rat descending colon was investigated by immunofluorescent staining and confocal laser scanning techniques, and goblet cells were further investigated by wheat-germ agglutinin histochemistry. In addition, GAD65 and GAD67 mRNAs were also detected by reverse transcription-polymerase chain reaction. Furthermore, evaluation of cell kinetics in colonic epithelia was conducted by ABC immunostaining using a monoclonal antibody against proliferating cell nuclear antigen (PCNA). RESULTS: Immunoreactive GABA and GADs were distributed in the upper third of the crypts and at the luminal surface in the rat descending colon. Strong staining for GABA and GADs was localized mainly in the cytoplasm of epithelial cells near the neck of the crypts and along the luminal surface. In addition, GABA and GAD65 were also detected at the lamina propria in colonic mucosa. No staining for GABA or GADs was found in goblet cells. GAD65 and GAD67 mRNAs were identified in homogenates of rat descending colon. PCNA labeled nuclei were found in the lower two-thirds of the crypts. CONCLUSIONS: The expression of GABA and GADs in the maturation and function zones of rat descending colon suggests that GABA may be involved in the differentiation of colonic epithelial cells.

Animals↗
PubMed1979

Epithelial cell kinetics in the descending colon of the rat. II. The effect of experimental bypass.

The influence of experimental bypass on the epithelial cell kinetics in the rat descending colon was studied. It was found that the number of cells per crypt was markedly reduced at 6 weeks after bypass. The percentage of labelled crypt cells, 1 h after 3HTdR, and the distribution of labelled cells in the crypt was normal. Also the life span of the epithelial cells was the same in control and bypassed colon. The response of crypt cell proliferation to ischaemia-induced cell loss in the bypassed descending colon was similar to the one previously described for normal descending colon. This indicates that the absence of the normal luminal contents does not result in a different response of colonic crypts to induced cell loss. Furthermore, it was found that the number of cells per crypt and the proliferative activity did not change in the transverse colon after temporary ischaemia of the bypassed descending colon. This indicates that the increase in crypt cell proliferation after ischaemia-induced cell loss is a local response.

Animals↗
PubMedDate not supplied

A modified teniotomy technique for facilitated removal of descending colon enteroliths in horses.

OBJECTIVE: To describe a method for facilitating movement of enteroliths obstructing the proximal portion of the descending colon. STUDY DESIGN: Prospective report. SAMPLE POPULATION: 15 horses. METHODS: A seromuscular incision through the antimesenteric taenia of the proximal portion of the descending colon was used to facilitate movement of enteroliths. RESULTS: Teniotomy allowed proximal descending colon enteroliths located within the abdomen or close to the abdominal wall to be advanced 4 to 15 cm in an aboral direction so that they could be exteriorized for safe removal. CONCLUSIONS AND CLINICAL RELEVANCE: Teniotomy is a feasible method for mobilizing enteroliths in the proximal descending colon in locations that cannot otherwise be exteriorized.

Animal Feed↗
PubMed1997

The effects of combined distension of the stomach and the descending colon on coronary blood flow in anaesthetized pigs.

The effects of the combined distension of the stomach and the descending colon on coronary blood flow were examined in seven alpha-chloralose anaesthetized pigs whilst preventing changes in heart rate and aortic blood pressure. Changes in coronary blood flow in the left circumflex or anterior descending coronary artery were assessed using electromagnetic flowmeters during distension with Ringer solution of balloons positioned in the viscera. In a first set of studies, graded distension of the stomach with distending volumes of 0.8, 1.1 and 1.4 l always caused graded decreases in coronary blood flow. The additional distension of the descending colon at a distending volume of 0.25 l augmented the response of decrease in coronary blood flow caused by the first two levels of gastric distension, but it did not have any further effect when added to the higher level of gastric distension. Similar results were obtained in a second set of studies in which distension of the stomach at a volume of 0.8 l was additionally performed during graded distension of the descending colon with distending volumes of 0.25, 0.35 and 0.45 l. These effects elicited by combined distension of the two viscera were not affected by the administration of propranolol, but they were abolished by subsequent administration of phentolamine. The results showed that combined distension of the stomach and the descending colon in anaesthetized pigs augmented the reflex response of coronary vasoconstriction and that the response to distension of one viscus was attenuated during increased levels of distension of the other viscus. These combined responses to distension of the two viscera involved efferent sympathetic mechanisms related to alpha-adrenoceptors.

Adrenergic alpha-Antagonists↗
PubMed1991

Reflex effects of descending colon distension on coronary blood flow in anesthetized dogs.

To find out whether distension of the descending colon reflexly affects coronary blood flow, experiments were performed in nine dogs anesthetized with pentobarbitone. The descending colon was isolated between ligatures and distended with warm Ringer solution at a steady intraluminal pressure. Arterial blood pressure was prevented from changing by withdrawing blood from the left femoral artery. In two of the nine dogs the arterial blood pressure was also kept constant by tightening a plastic snare round the thoracic aorta. The reflex increase in heart rate was prevented by atrial pacing. Distension of the descending colon at constant heart rate and arterial blood pressure always caused a decrease in mean coronary blood flow, amounting to 2.44 +/- 1.8 ml/min (mean +/- SD), equal to a percent decrease of 14.3 +/- 10.5. This response was completely abolished by section of the hypogastric nerves, thus demonstrating that a reflex mechanism is involved.

Animals↗
PubMed2004

Primary, solitary, adult T-cell leukemia / lymphoma of the descending colon.

We herein report a patient with adult T-cell leukemia/lymphoma (ATLL) of the descending colon. A 64-year-old man was admitted to our hospital complaining of left lower abdominal pain. Endoscopic examination revealed an ulcerative tumor in the descending colon that was diagnosed as T-cell lymphoma by biopsy. Neither distant organ metastasis nor lymph node swelling was observed by radiographic examinations. Curative excision with left hemicolectomy and regional lymph node dissection was performed. Surgical sections contained ulcerative and superficially elevated lesions; these were continuous with each other. Histological examination revealed diffuse proliferation of medium-sized abnormal lymphoid cells. Immunohistochemically, these lymphoid cells were positive for UCHL-1/CD45RO and CD3 and negative for CD79a, indicating that the tumor was a primary malignant T-cell lymphoma of the descending colon. Integration of the proviral DNA of human T-lymphotropic virus type 1 (HTLV-1) was confirmed by Southern blotting analysis.

Aged↗
PubMed2005

Matrices for site-specific controlled-delivery of 5-fluorouracil to descending colon.

Colon-specific controlled-delivery 5-fluorouracil (5-FU) matrices for the treatment of colorectal carcinoma were prepared and evaluated. Matrices are destined to be introduced into enteric-coated capsules and thereby carried to and liberated in the ileum. There, drug release should be prevented until matrices reach descending colon where release should occur. Matrices (50 mg, diameter 0.6 mm) were prepared by compression of powders or of granules prepared by melt granulation. The ingredients comprised 30-70% w/w 5-FU, glyceryl palmitostearate as rate-controlling material and 5% w/w Aerosil as glidant. Drug release was measured by the rotating basket method. The matrix containing 60% w/w drug, prepared by compression of powders, was appropriate to make the planned system, in virtue of its fairly high drug load and its nearly constant and reasonable release rate. This matrix was spray-coated with Eudragit S100 (EUD). Subsequently, an external layer of chitosan hydrochloride (CH-HCl) was applied by a dipping-drying technique. When transit of coated matrix through ileum (phosphate buffer (PB) pH 7.4), ascending colon (PB pH 6 containing rat cecal contents) and descending colon (PB pH 7.4) was simulated in vitro, the pH 4.7 of the CH-HCl gel layer and the pH 6 of the ascending colon prevented dissolution of the protective EUD film until descending colon was reached, then controlled release started. The present small matrices can enter size no. 00 capsules. Considering that each capsule contains 10 matrices, the maximal dose is 300 mg.

Animals↗
PubMed2006

Comparative study of descendent colon rupture resistance considering traction force of rupture and total energy of rupture in rats.

PURPOSE: To compare total energy of rupture and traction force of rupture tests within a rupture resistance study of descendent colon of rats. METHODS: Twelve descendent colon segments of rats were considered to perform the study. For each one of the specimens, total energy of rupture and traction force of rupture necessary to promote colic wall burst were evaluated through the biomechanical total energy of rupture test using the Biomechanical Data Acquisition and Analysis System, version 2.0. Average, standard deviation, standard error of average and coefficient of variation were considered for analysis of results. RESULTS: Traction force of rupture average, standard deviation, standard error of average and coefficient of variation were 380.05 gf, 98.74, 28.5 e 25.98%, respectively while total energy of rupture presented average of 244.85 gf, standard deviation of 57.76, standard error of average of 16.67 and coefficient of variation of 23.59. CONCLUSION: Although, total energy of rupture considered a larger number of attributes to its calculation related to non-linear viscoelastic materials, such as colic wall, it presented a smaller coefficient of variation when compared to traction force of rupture, thus demonstrating to constitute a possible parameter to analyze intestinal resistance of rats.

Animals↗
PubMed1987

Thallium(I) secretion across the isolated mucosa of rat descending colon.

Unidirectional Tl+-fluxes across the isolated mucosa of rat descending colon were measured under short circuit (SCC) or voltage clamp conditions (VCC). Under SCC a serosal-to-mucosal net flux (Jnet = -0.22 nmol X cm-2 X h-1) was observed that agrees with the voltage-independent component measured under VCC. At 7 degrees C the secretory net flux was abolished. In controls both unidirectional fluxes were unsaturable between 0.1 and 500 mumol/l thallium (I). After furosemide or withdrawal of Cl- or Na+ Jnet was abolished. Ouabain decreased serosal-to-mucosal Tl+ flux and an energy-dependent absorptive net flux of Tl+ was observed, characterized by a rather low Km (10.2 mumol/l), Vmax (3.8 nmol X cm-2 X h-1) and apparent activation energies (delta E = 10.7 kcal X mol-1) typically for enzyme catalaysed reactions or narrow channel interactions. The data suggest that in the mucosa of rat descending colon Tl+ ions share, at least in part, the same transport systems at K+.

Animals↗
PubMed1991

Quantification of acid mucins in the descending colon of rats having simultaneously growing colonic tumors.

The acid mucins contained in goblet cells of the descending colon of 34 male Sprague-Dawley rats were histochemically labeled by Alcian blue pH 2.5 and quantified in an image analyzer (Cortex Controller). Twenty-two of these 34 rats were treated with 1,2-dimethylhydrazine (DMH) suspended in EDTA solution as a stabilizing agent and the remaining 12 rats with EDTA only. Of the 22 DMH-treated rats, 11 had concomitantly an adenocarcinoma elsewhere in the colon and the remaining 11 rats had no colonic tumors despite DMH treatment. The results indicated that Alcian blue-positive areas occupied 34.5% of the mucosa of the descending colon in tumor-bearing rats, and 35.2% in non-tumor-bearing DMH-treated rats. For EDTA-treated rats the percentage of mucosa occupied by Alcian blue-positive cells was 48.1%. The difference between DMH-treated rats (with or without tumors) and EDTA-treated rats was significant (p less than 0.001). These results suggest that the decrease of Alcian blue areas is related to the protracted treatment with DMH. Whether the decrease in acid mucins is induced by the carcinogen per se or whether it represents a true biochemical premalignant change at the cytoplasmic level remains to be elucidated.

1,2-Dimethylhydrazine↗