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PubMed2004

Virtual colon dissection with CT colonography compared with axial interpretation and conventional colonoscopy: preliminary results.

OBJECTIVE: The aim of this study was to determine whether a new virtual colon dissection 3D visualization technique for CT colonography has a shorter analysis time and better sensitivity for detection of colonic polyps than interpretation of axial CT images. SUBJECTS AND METHODS. CT colonography was performed in 22 patients using 4-MDCT followed by conventional colonoscopy on the same day. The CT colonography data sets were analyzed by virtual colon dissection, which virtually bisects and unfolds the colon along its longitudinal axis to inspect the inner colonic surface for polyps. The same CT data sets were independently evaluated using axial interpretation. All data sets were independently interpreted by two radiologists in a blinded manner. RESULTS: Conventional colonoscopy revealed 31 colonic lesions in 20 patients. Twenty two of the lesions were smaller than 10 mm; nine were 10 mm or larger. Two of the original 22 patients were excluded, one because of residual stool and fluid and the other because of an impassable stenosing rectal wall cancer. For virtual colon dissection, the per-lesion sensitivity was 42% for observer 1 and 68% for observer 2; for axial interpretation, the respective sensitivities were 48% and 61%. For polyps 10 mm or larger, the respective sensitivities were 67% and 89% for virtual colon dissection and 89% and 100% for axial interpretation. The average time for reconstruction and analysis of virtual colon dissection was 36.8 min versus 29.2 min for axial images. Virtual colon dissection was feasible in both the supine and the prone positions in 45.5% of colonic segments, in either the supine or the prone position in 24.5%, and in neither position in 30% of segments. CONCLUSION: Although virtual colon dissection may facilitate detection of colonic polyps in isolated cases, its detection rate is not superior to axial interpretation, which is mainly attributable to failed rendering of insufficiently distended colonic segments or regions with residual feces. Virtual colon dissection is also the more time-consuming of the two procedures. With further improvement of path-finding and image segmentation, however, virtual colon dissection has the potential to be a useful interpretation tool for CT colonography.

Adult↗

PubMed2003

Measuring colonic transit time in chronic idiophatic constipation.

INTRODUCTION AND OBJECTIVES: Colonic transit time can define three types of delay: right colon (colonic inertial), left colon and recto sigmoid. The aim of this study is to compare clinic characteristics and manometric results among the different groups with segmental colonic transit disorder. PATIENTS AND METHODS: 61 subjects were included in our study (5 men and 56 women) with and average age of 47.5 years (range: 17-84 years). We carried our a study of segmental and total colonic transit time, with the use of radio-opaque markers and sequential abdominal X-rays. We considered that transit time was prolonged when it was longer than 72 hours, and segmental transit time, when right colon was longer than 22 hours, left colon 37.2 hours and recto-sigmoid 37.2 hours. We included different clinic data: age, sex, place of residence stool frequency, abdominal pain, painful evacuation, incomplete evacuation, evacuation desire, dietary fibre intake, use of laxatives. We practised anorectal manometry in 20 patients. RESULTS: The average total colonic transit time was 38.2 hours in normal transit and 103 hours with disorder. The frequency in the three colonic segments, when there was a long total colonic transit time, was: 40% in the left colon, 33% in the recto-sigmoid and 27% in the right colon. We analysed the clinical characteristics of these three groups, finding more frequency of painful evacuation and defecation desire and lower dietary fibre intake in recto sigmoid. The most important abnormality in anorectal manometry was the hiposensitivity in the anorectal area, that only appeared in subjects with long segmental transit time in the right colon (colonic inertia), statistically significant. CONCLUSIONS: The measurement of colonic transit time with radio-opaque markers is a simple technique that allows for the objective detection of the different groups of patients with chronic idiopathic constipation. The exact typification of the abnormality is important for the individualization of each treatment.

Adolescent↗

PubMed1994

Characterization of the hemodynamic and metabolic alterations in the large colon of horses during low-flow ischemia and reperfusion.

Effects of low-flow ischemia and reperfusion of the large colon on systemic and colonic hemodynamic and metabolic variables were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. Heart rate, arterial blood pressures, cardiac index, pulmonary artery pressure, right atrial pressure, and colonic blood flow were monitored. Arterial, mixed-venous, and colonic venous blood gas and oximetry analyses; PCV; and blood lactate and pyruvate and plasma total protein concentrations were measured. Data were recorded, and blood samples were collected at baseline and at 30-minute intervals for 6 hours; additionally, data were collected at 185, 190, and 195 minutes (corresponding to 5, 10, and 15 minutes of reperfusion in group-3 horses). There were no differences among groups at baseline or across time for any systemic hemodynamic or metabolic variable. Colonic blood flow did not change across time in group-1 horses. Colonic blood flow significantly (P < 0.05) decreased to 20% of baseline at induction of ischemia in horses of groups 2 and 3 and remained significantly decreased throughout the ischemic period in horses of groups 2 (6 hours) and 3 (3 hours). Colonic blood flow significantly (P < 0.05) increased above baseline by 5 minutes of reperfusion in group-3 horses. Colonic oxygen delivery and oxygen consumption, and colonic venous pH, PO2, percentage saturation of hemoglobin, and oxygen content were significantly (P < 0.05) decreased within 30 minutes after induction of ischemia in horses of groups 2 and 3; colonic venous PCO2, colonic oxygen extraction ratio, and lactate and pyruvate concentrations were significantly (P < 0.05) increased by 30 minutes of ischemia. These alterations continued throughout ischemia, but within 5 minutes of reperfusion in group-3 horses, these variables either returned to baseline (pH, PCO2, lactate, pyruvate), significantly (P < 0.05) increased above baseline (PO2, oxygen content, % saturation of hemoglobin), or significantly (P < 0.05) decreased below baseline (colonic oxygen extraction ratio). Colonic oxygen consumption remained decreased during reperfusion in group-3 horses. Colonic mucosal ischemia-reperfusion injury observed in this model of ischemia was associated with local colonic hemodynamic and metabolic alterations in the presence of systemic hemodynamic and metabolic stability.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2005

Staphylococcus aureus colonization and the risk of infection in critically ill patients.

OBJECTIVE: To evaluate the relationship between Staphylococcus aureus nasal and tracheal colonization and infection in medical intensive care unit (MICU) patients. The primary outcome was the incidence of S. aureus infection in colonized versus non-colonized patients. DESIGN: Prospective, observational cohort study. Patients admitted to the MICU during the study period were screened for S. aureus nasal and tracheal colonization by culture and a PCR assay twice weekly. Demographic, clinical, and microbiologic data were collected in the MICU and for 30 days after discharge. PFGE and antibiotic susceptibility testing were performed on all S. aureus nasal, tracheal, and clinical isolates. RESULTS: Twenty-three percent of patients (47 of 208) were nasally colonized with S. aureus. Twenty-four percent of these patients developed S. aureus infections versus 2% of non-colonized patients (P < .01). Nine of 11 patients with both nasal colonization and infection were infected by their colonizing strain. Two of 47 nasally colonized patients developed an infection with a different strain of S. aureus. Fifty-three percent of intubated patients with nasal colonization (10 of 19) had tracheal colonization with S. aureus as opposed to 4.9% of intubated, non-colonized patients (3 of 61) (P < .01). Parenteral antibiotics were ineffective at clearing nasal colonization. PCR detected S. aureus colonization (nasal and tracheal) within 6.5 hours with a sensitivity of 83% and a specificity of 99%. CONCLUSIONS: The incidence of S. aureus infection was significantly elevated in nasally colonized MICU patients. Techniques to rapidly detect colonization in this population may make targeted topical prevention strategies feasible.

Anti-Bacterial Agents↗

PubMed1999

Bacterial colonization patterns in mechanically ventilated patients with traumatic and medical head injury. Incidence, risk factors, and association with ventilator-associated pneumonia.

We prospectively evaluated the relation of upper airway, lower airway, and gastric colonization patterns with the development of pneumonia and its etiology in 48 patients with surgical (n = 25) and medical (n = 23) head injury. Initial colonization was assessed by cultures of nasal and pharyngeal swabs, tracheobronchial aspirates, gastric juice, and bronchoscopically retrieved protected specimen brush. Follow-up colonization was determined until the end points extubation, suspected ventilator-associated pneumonia (VAP), or death. The initial colonization rate at any site at ICU admission was 39/47 (83%). It mainly accounted for Group I pathogens (Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae) of the upper and lower airways. At follow-up, colonization rates with Group II pathogens (Gram-negative enteric bacilli and Pseudomonas spp.) increased significantly. The high initial bacterial load with Group I pathogens of the upper airways and trachea decreased during Days 2 to 4, whereas that of Group II pathogens increased. Upper airway colonization was an independent predictor of follow-up tracheobronchial colonization (odds ratio [OR], 9.9; 95% confidence interval [CI], 1.8 to 56.3 for initial colonization with Group I pathogens; OR, 23.9; 95% CI, 3.8 to 153.3 for follow-up colonization with Group II pathogens). Previous (short-term) antibiotics had a protective effect against colonization with Group I pathogens of the lower respiratory tract (OR, 0.2; 95% CI, 0.05 to 0.86), but they were a risk factor for colonization with Group II pathogens (OR, 6.1; 95% CI, 1.3 to 29). Initial tracheobronchial colonization with Group I pathogens was associated with a higher probability of early onset pneumonia (OR, 4. 1; 95% CI, 0.7 to 23.3), whereas prolonged antibiotic treatment (> 24 h) independently predicted late-onset pneumonia (OR, 9.2; 95% CI, 1.7 to 51.3). We conclude that patients with head injury are colonized in the airways mainly by Group I pathogens early in the evolution of illness. The upper airways represent the main reservoir for subsequent lower airway colonization with Group I pathogens. Previous (short-term) antibiotic treatment is protective against initial tracheobronchial colonization with Group I pathogens, but it represents a risk factor for subsequent lower airway colonization by Group II pathogens.

Adult↗

PubMed1985

Steroid receptors in dimethylhydrazine-induced colon carcinogenesis.

To investigate whether gonadal hormones are involved in the tumorigenesis of dimethylhydrazine (DMH)-induced colonic neoplasms, the authors measured steroid receptors in the neoplasms. 30- or 60-day-old BD-IX rats were injected with 20 mg of 1,2-DMH per kg of body weight once a week for 20 weeks. Fifty-seven rats were sacrificed at 40 to 45 weeks after the initial injection. Androgen receptor (AR), estrogen receptor (ER), and progesterone receptor (PR) were measured in colonic neoplasms. The total number of colonic neoplasms was 274 among 57 rats, 65.8% in male rats and 34.2% in female rats. The mean number of colonic neoplasms per rat was higher in male rats, i.e., 5.6, compared with 3.5 in female rats. A slightly higher number of colonic neoplasms per rat was seen in the rats that had the initial injection at 30 days of age. The number of large colonic neoplasms with a diameter of more than 1 cm was 77 (28.1%), 74% of which were seen in male rats. Thus, a higher incidence of tumors that were also larger were seen in male rats. Histologic findings showed that 53.6% of the neoplasms were carcinomas. The highest incidence of colonic neoplasms was in the distal colon in both sexes. Most of the well-differentiated adenocarcinoma were seen in the distal colon (82.2%), whereas mucinous carcinoma and undifferentiated adenocarcinoma were prominent in the proximal colon or cecum (56.1%). In rats with a normal colon, low levels of AR and PR were determined; but ER was not found in any regions of the colon. In DMH-induced colonic cancer, the incidence as well as the concentration was higher in male rats (60.6%, 16.9 +/- 3.6 fm/mg protein), compared with female rats (40.0%, 4.6 +/- 0.8 fm/mg protein). Similar incidences and levels of ER and PR were seen in both sexes. There was no relationship between steroid receptors and histologic findings in colonic neoplasms. These results suggest that the gonadal hormones, especially androgens, appear to be involved in DMH-induced colon tumorigenesis in male rats.

1,2-Dimethylhydrazine↗

PubMed1997

Mucosal changes in interposed colon segment as gastric substitute following gastrectomy in rats.

BACKGROUND: An interposed colon segment has been clinically reconstructed as a gastric substitute. The purpose of this study is to establish a rat model of colonic interposition and to investigate serial mucosal changes and adaptation of interposed colon mucosa under prolonged exposure to bile and pancreatic juice reflux. METHODS: About 80% of the glandular stomach was resected, and a 3-cm segment of the transverse colon interposed isoperistaltically between the remnant stomach and duodenum. Epithelial proliferation, aberrant crypt foci (ACF), and tumors in the interposed colon segment were investigated after 4 months of administration of N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) to rats (ENNG-treated rats). RESULTS: In the interposed colon, crypt lengths increased significantly, and the number of goblet cells per crypt per 1 mm decreased significantly compared to those in the remnant colon, whether ENNG was administered or not. Both crypt lengths and the number of goblet cells in the interposed colon of controls and ENNG-treated rats showed no significant difference. A proliferating cell nuclear antigen (PCNA) labeling index (LI) of the remnant colon was almost 30% in both controls and ENNG-treated rats. In controls, the PCNA LI in the interposed colon at 4, 8, and 12 months after surgery was 30.8, 31.8, and 47.8%. In ENNG-treated rats, the PCNA LI in the nontumorous mucosa of the interposed colon was 44.9, 55.4, and 61.5% at the above postsurgical intervals. ACF and carcinoma were observed only in the interposed colon of ENNG-treated rats. ACF was observed as early as 4 months after surgery, and its incidence increased serially. Both the incidence of carcinogenesis and the number of tumors had increased 8 months after surgery. CONCLUSIONS: We established a rat model of colonic interposition following gastrectomy. The adaptation of interposed colon mucosa was well conducted. A malignant condition, however, was induced in the interposed colon segment serving as a gastric substitute because of both carcinogen predisposition and prolonged exposure to bile and pancreatic juice reflux.

Adaptation, Physiological↗

PubMed2005

Comparison of one-stage resection and anastomosis of acute complete obstruction of left and right colon.

BACKGROUND: Although acute obstruction of the right colon is usually handled by primary anastomosis following resection, many surgeons are reluctant to offer one-stage resection and anastomosis to patients with obstructive lesions of the left colon. The aim of the study is to compare the immediate result of one-stage resection and anastomosis for patients with acute complete obstruction of the right colon versus left colon. METHODS: From January 1986 to December 2003, 214 cases of acute colonic obstruction were managed with one-stage resection and anastomosis by a single surgeon. Eighty patients were operated on for obstructive lesions of the right colon, 71 of them for carcinoma of the colon. Operative mortality was 10% (8/80); all except 2 patients died of respiratory failure. There were 2 cases (2.5%) of anastomotic leakage. One hundred thirty-four patients were operated on for obstructive lesions of the left colon, 127 of them for carcinomas of the colon and rectum. Operative mortality was 1.5% (2/134); both patients died of metastasis from the colorectal cancer following surgery. There were 3 cases (2.3%) of anastomotic leakage. CONCLUSION: This experience suggests that an anastomosis can be performed as safely in patients with acute obstruction of the left colon as in those with acute obstruction of the right colon. Mortality following resection and anastomosis is actually lower in left than right colonic obstruction. Neither intraoperative irrigation nor routine subtotal colectomy was found to be necessary in patients with acute colonic obstruction. Intraoperative decompression should be considered in left and also right colonic obstruction prior to the anastomosis following colonic resection.

Acute Disease↗

PubMed1998

Review article: colonic sensorimotor physiology in health, and its alteration in constipation and diarrhoeal disorders.

AIM: To review the physiology of colonic motility and sensation in healthy humans and the pathophysiological changes associated with constipation and diarrhoea. SOURCE: Medline Search from 1965 using the index terms: human, colonic motility, sensation, pharmacology, neurohormonal control, gastrointestinal transit, constipation, diarrhoea and combinations of these. RESULTS: In health, the ascending and transverse regions of colon function as reservoirs to accommodate ileal chyme and the descending colon acts as a conduit; the neuromuscular functions and transmitters control colonic motility and sensation and play pivotal roles in disorders associated with constipation and/or diarrhoea. Disorders of proximal colonic transit contribute to symptoms in idiopathic constipation, diarrhoea-predominant irritable bowel syndrome and carcinoid diarrhoea. Colonic function in patients presenting with constipation is best assessed clinically by colonic transit time using radiopaque markers ingested orally. Measurements of colonic contractility are less useful clinically but they can help identify motor abnormalities including colonic inertia; in some patients with irritable bowel syndrome, abdominal pain, urgency and diarrhoea are temporally associated with high amplitude contractions, which originate in the proximal colon and traverse the distal conduit at very high propagation velocities. Visceral hypersensitivity contributes to the urgency and tenesmus in irritable bowel syndrome and inflammatory bowel disease. Colonic motility and sensation can be reduced by anticholinergic agents, somatostatin analogues and 5HT3 antagonists. CONCLUSION: Physiological and pharmacological studies of the human colon have provided new insights into the pathophysiology of colonic disorders, and offer possibilities of novel therapeutic approaches for constipation or diarrhoea associated with colonic motor or sensory dysfunction.

Colon↗

PubMedDate not supplied

Correlations between colonic wall thickening in patients with virally induced cirrhosis on CT and clinical status.

PURPOSE: The purpose of this work was to determine the frequency and CT imaging spectrum of colonic wall thickening and correlate these with the clinical severity of virally induced cirrhosis. METHOD: Fifty-nine patients were identified with virally induced cirrhosis and no other causes of colonic wall thickening. The abdominal CT scans of these patients were retrospectively reviewed by two radiologists to determine the presence of colonic wall thickening from the ascending colon to the descending colon, to assess the segmental distribution, and to correlate these findings with the clinical status assessed by Child-Pugh classification, presence of ascites, splenic volume index, varices score, and serum albumin levels. RESULTS: Colonic wall thickening was identified in 18 (31%) patients. The frequency of the affected distribution of colonic wall thickening was as follows: ascending colon in 17 (29%) patients, transverse colon in 11 (19%) patients, and descending colon in 7 patients (12%). The ascending colon was the most common site of colonic wall thickening (p < 0.001). Ten (17%) patients had multisegmental distributions. Colonic wall thickening had a statistically significant association with Child-Pugh grades A, B, and C (p < 0.0001), presence of ascites (p < 0.0004), splenic volume index (p = 0.0026), varices score (p < 0.0001), and serum albumin levels (p = 0.0364). The segmental distribution of wall thickening significantly correlated with Child-Pugh grades A, B, and C (p = 0.0005), presence of ascites (p < 0.001), varices score (p < 0.0001), serum albumin levels (p < 0.0001), and splenic volume index (p = 0.0135). CONCLUSION: Colonic wall thickening occurs commonly in patients with virally induced cirrhosis. The presence and number of colonic wall thickening were correlated with the grading of the severity of cirrhosis.

Adolescent↗

PubMedDate not supplied

Effect of platelet-activating factor antagonist L-691,880 on low-flow ischemia-reperfusion injury of the large colon in horses.

OBJECTIVE: To determine the effect of platelet-activating factor (PAF) antagonist L-691,880 on low-flow ischemia and reperfusion (I-R) of the large colon in horses. ANIMALS: 12 adult horses. EXPERIMENTAL DESIGN: Horses were anesthetized, and the large colon was exteriorized through a ventral median celiotomy and instrumented. Colonic arterial blood flow was reduced to 20% of baseline (BL) and maintained for 3 hours; flow was then restored, and the colon was reperfused for 3 hours. One of two solutions was administered intravenously 30 minutes before reperfusion: group 1, 10 mL/kg 0.9% NaCl; and group 2, 5 mg/kg PAF antagonist L-691,880 in 0.9% NaCl. Hemodynamic variables were monitored and recorded at 30-minute intervals. Systemic arterial and colonic venous blood were collected for measurement of blood gas tensions, oximetry analyses, packed cell volume, and total plasma protein concentrations. Colonic venous blood was collected for determination of lactate, 6-keto prostaglandin F1 alpha (6-kPG), prostaglandin E2 (PGE2), and thromboxane B2 (TXB2) concentrations. Full-thickness biopsy specimens were harvested from the left ventral colon for histological evaluation. RESULTS: There were no significant differences between the two groups for any hemodynamic or metabolic variables. Colonic venous pH decreased, and carbon dioxide tension and lactate concentration increased during ischemia but returned to BL values during reperfusion. Colonic venous 6-kPG concentration was significantly increased above BL value at 2 hours and remained increased through 6 hours in horses of both groups. Colonic venous PGE2 concentration was significantly greater in group 2 compared with group 1 throughout the study. Colonic venous PGE2 concentration was increased above BL value from 3 to 6 hours in horses of both groups. Colonic venous TXB2 concentration was not different between groups but was significantly increased above the BL value for the first hour of reperfusion. Low-flow I-R of the large colon caused significant mucosal necrosis, hemorrhage, edema, and neutrophil infiltration; however, there were no differences in histological variables between vehicle-control and PAF antagonist-treated horses. CONCLUSION: No protective effects of PAF antagonist L-691,880 were observed on colonic mucosa associated with low-flow I-R. Additionally, deleterious drug-induced effects on hemodynamic and metabolic variables and colonic mucosal injury were not observed.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

Morphologic and quantitative evaluation of the myenteric plexuses and neurons in the large colon of horses.

OBJECTIVE: To determine the number of myenteric plexuses and neurons in the large colon of clinically normal horses and whether the number was decreased in the large colon of horses with colon disease. DESIGN: Prospective study. SAMPLE POPULATION: Colon samples from 15 clinically normal horses and 31 horses with colon disease. PROCEDURE: Samples were obtained, fixed, and stained with H&E. The number of myenteric plexuses and neurons and longitudinal muscle thickness were determined in each segment of colon for clinically normal horses. Counts for segments were compared with each other and with counts in the same segment from horses with colon disease. RESULTS: Myenteric plexus and neuron densities and longitudinal muscle thickness in clinically normal horses were significantly greater in the pelvic flexure and left dorsal and transverse colons. Horses with chronic obstruction (> 24 hours' duration) or with previous obstruction had significantly lower neuron density in the pelvic flexure. Myenteric plexus density in horses with strangulating large colon torsion/volvulus was significantly less in the right ventral, right dorsal, and transverse colons, and neuron density in these horses was significantly less in all segments of colon, except the left ventral colon. Horses with colon strangulation that survived had significantly greater neuron density than horses with colon strangulation that died. Enteroglial cell numbers were increased in myenteric plexuses of horses with acute and chronic obstruction. CLINICAL IMPLICATIONS: Myenteric plexus and neuron densities can be estimated by evaluating linear counts of H&E-stained colon samples. Enteroglial cells may increase in number in response to myenteric plexus inflammation, which may affect bowel function.

Animals↗

PubMed1987

Segmental variability of membrane conductances in rat and human colonic epithelia. Implications for Na, K and Cl transport.

The membrane conductances in proximal and distal segments of rat and human colon were studied with microelectrodes, nystatin, ion channel blockers and Cl replacement. The results reveal that (1) in rat colon, total conductance (Gt) is greater in the proximal segment than in the distal segment, reflecting greater values of apical (Ga) and paracellular shunt (Gs) conductances in the proximal segment; in contrast, in human colon, Gt and its individual membrane components are similar in the proximal and distal segments, and lower than the corresponding values in rat colon; (2) amiloride sensitive apical Na conductances are absent in rat proximal colon, rat distal colon, and human proximal colon, but in human distal colon amiloride produces changes consistent with blockade of an apical Na conductance and inhibition of electrogenic Na transport; (3) a TEA-sensitive apical K conductance may be present in rat proximal colon (a K secretory epithelium), but not in rat distal colon (a K absorptive epithelium) or in either segment of human colon; and (4) in rat colon, replacement of mucosal and serosal Cl produces changes consistent with a substantial paracellular shunt permeability to Cl which is more marked in the proximal segment, whereas in human colon Cl replacement results in changes which suggest a relatively small paracellular shunt permeability to Cl which is similar in both segments. These data indicate marked segmental differences in Na, K and Cl transport in rat and human colon, and emphasise the hazards of applying models of colonic electrolyte transport in one species to another.

Adult↗

PubMed1988

Sustained increase in the proliferation of rat colonic mucosa during chronic treatment with aspirin.

The effects of indomethacin and aspirin on colonic epithelial proliferative activity, colonic prostaglandin synthesis, and colonic mucosal cyclic adenosine 3',5'-monophosphate content were examined. Administration of indomethacin (3 mg/kg.day, s.c.) for 2 wk suppressed ex vivo colonic prostaglandin E2 production by 50% and increased [3H]thymidine incorporation into mucosal DNA in vivo, but induced colonic inflammation. Higher doses of indomethacin were toxic and associated with high mortality. By contrast, administration of aspirin (50 mg/kg.day, s.c.) for 2-20 wk suppressed colonic prostaglandin E2 production by 97% and was unassociated with colonic inflammation or systemic toxicity. Suppression of colonic prostaglandin E2 production was associated with a sustained stimulation of [3H]thymidine incorporation into colonic mucosal deoxyribonucleic acid (2-20 wk) and an increase in the [3H]thymidine labeling index when examined at 20 wk. Basal cyclic adenosine 3',5'-monophosphate content of colonic mucosa was markedly reduced in aspirin-treated rats. Moreover, addition of dimethyl prostaglandin E2 or 8-Br-cyclic adenosine 3',5'-monophosphate suppressed the elevated levels of [3H]thymidine incorporation into mucosal deoxyribonucleic acid in incubated colonic segments from aspirin-treated rats. The results demonstrate that sustained suppression of colonic prostaglandin synthesis by aspirin is associated with a persistent increase in colonic epithelial proliferative activity. They support a role for local colonic prostaglandin synthesis as a negative modulator of epithelial growth, possibly mediated through increases in colonic mucosal cyclic adenosine 3',5'-monophosphate.

Animals↗

PubMed2006

Wood creosote prevents CRF-induced motility via 5-HT3 receptors in proximal and 5-HT4 receptors in distal colon in rats.

Wood creosote has been used as an herbal medicine against acute diarrhea caused by food poisoning and has an inhibitory effect on colonic motility and enterotoxin-induced ion secretion. Since no previous studies have examined the effects of wood creosote on stress-induced alteration of colonic motility, we examined the effects on the colonic motility altered by intracerebroventricular (i.c.v.) injection of corticotropin-releasing factor (CRF), which is a key mediator in responses to stress. We recorded motor activity in proximal and distal colon of unrestrained conscious rats via two manometory catheters. The frequencies of phase III-like contraction and the % motor indices in both proximal and distal colon were measured. At the same time the number of fecal pellets excreted was counted. I.c.v. injection of CRF increased the motor activity in both proximal and distal colon, and these effects were completely antagonized by i.c.v. injection of a selective CRF type 1 antagonist but not by a CRF type 2 antagonist. Changes in colonic motility induced by CRF were reversed by intravenously administered wood creosote. Intraluminal administration of the 5-HT(3) receptor antagonist granisetron, or the 5-HT(4) receptor antagonist SB 204070 blocked the increase in colonic motility induced by i.c.v. injection of CRF. Wood creosote prevented the increase in colonic motility induced by the 5-HT(3) receptor agonist SR57227A in the proximal colon, while it prevented the increase in colonic motility induced by the 5-HT(4) receptor agonist RS67506 in the distal colon. These results indicate that wood creosote prevents the increase in colonic motility induced by CRF via 5-HT(3) receptors in the proximal colon, and via 5-HT(4) receptors in the distal colon, suggesting that wood creosote might be useful to treat stress-induced diarrhea.

Animals↗

PubMedDate not supplied

Effect of colonic distention on ileal motor activity with evidence of coloileal reflex.

Chyme delivery from the ileum to the colon is controlled by various neurologic and hormonal factors, many of which remain to be identified. In this report we investigated the effect of colonic distention on ileal motility with the aim of identifying the mechanism of chyme delivery from the ileum to the colon. The right colon of 16 healthy volunteers (12 men and 4 women; mean age 36+/-9 years standard deviation) was distended by a balloon that was filled with saline solution in increments of 20 ml. The pressure response of the terminal ileum to the colonic distention was recorded by a saline-perfused tube. The test was repeated in nine subjects after the colonic segment around the balloon was anesthetized by xylocaine injection into the colonic wall. Twenty and 40 ml colonic distention produced no significant ileal pressure response. Colonic distention with 60 ml produced an increase in colonic pressure (P<0.05), as measured by intraballoon pressure, and a decrease in ileal pressure (P<0.05); a similar response was achieved with 80 ml distention. At 100 ml colonic distention, the balloon was dispelled to the transverse colon. Distention up to 100 ml of the anesthetized colonic segment produced no significant colonic or ileal pressure response. The flow of chyme from the small to the large gut appears to be controlled by a reflex mechanism that we call the "coloileal reflex." Whenever the right colon is distended with a substantial volume of chyme that increases the intraluminal pressure, it is suggested that ileal relaxation occurs, which delays the emptying of chyme from the ileum.

Adult↗

PubMed1998

Total and segmental colonic transit time with radio-opaque markers in adolescents with functional constipation.

BACKGROUND: In most instances, constipation is considered idiopathic or functional. The total and segmental colonic transit time, traced by radio- opaque markers, makes possible the identification of the colon segment that has the motility alteration that causes constipation. METHODS: A study was performed of 13 adolescents, aged 12 to 18, with functional chronic constipation and 13 without constipation. In all of them the total and segmental colonic transit times were measured with radio-opaque markers. The adolescents ingested 20 markers each on three successive days, and on the fourth day a plain abdominal radiograph was performed. RESULTS: In the nonconstipated adolescents the total colonic transit time (mean +/- SD) was 30.2 +/- 13.1 hours, in the right colon 5.7 +/- 3.9 hours, in the left colon 7.9 +/- 7.8 hours, and in the rectosigmoid 15.5 +/- 10.6 hours. In the constipated adolescents, the total colonic transit time was 58.3 +/- 17.4 hours, in the right colon 15.9 +/- 12.4 hours, in the left colon 14.7 +/- 13.4 hours, and in the rectosigmoid 17.2 +/- 16.2 hours. There was a statistically significant difference (p < 0.05) in the total colonic transit time, and in both the right and left colon transit times between constipated and nonconstipated adolescents. CONCLUSIONS: The measurement of total and segmental colonic transit times is a simple method that allows one to distinguish constipation due to colonic dysfunction (right colon and left colon) from constipation due to distal obstruction (rectosigmoid).

Adolescent↗

PubMed1971

Excitatory input from the distal colon to the inferior mesenteric ganglion in the guinea-pig.

1. Intracellular recordings were obtained from ganglion cells in the guinea-pig inferior mesenteric ganglion (IMG) with a segment of the distal colon attached to the lumbar colonic nerves.2. Continuous electrical activity consisting of excitatory synaptic potentials and action potentials was recorded from ganglion cells in all regions of the IMG.3. The ;spontaneous' synaptic potentials were indistinguishable from those elicited by submaximal stimulation of any of the nerve trunks connected to the IMG.4. The excitatory activity was irreversibly abolished when the lumbar colonic nerves were cut and reversibly abolished when tetrodotoxin (5 x 10(-7) g/ml.) was added to the colon side of a two-compartment organ bath.5. Addition of dihydro-beta-erythroidine (5 x 10(-6) g/ml.) to the ganglion side of the bath abolished the synaptic activity of colonic origin and the synaptic responses to stimulation of any of the nerve trunks connected to the IMG.6. Addition of dihydro-beta-erythroidine (1 x 10(-5) g/ml.) to the colon side of the bath markedly depressed the synaptic input of colonic origin but had no effect on synaptic responses produced by preganglionic nerve stimulation.7. Distension of the colonic segment and the application of 5-HT (1 x 10(-5) g/ml.) to the mucosal surface of the colon increased the frequency of synaptic input.8. The synaptic input from the colon was transiently blocked following repetitive stimulation of any of the nerve trunks connected to the IMG. The discharge of miniature synaptic potentials was unaffected.9. Addition of noradrenaline (1 x 10(-7) to 1 x 10(-6) g/ml.) to the colon side of the bath reduced, and in some cases completely abolished, the synaptic input to the IMG. Phentolamine (1 x 10(-6) g/ml.), when added to the colon side of the bath, blocked the effect of noradrenaline and the transient inhibition following repetitive nerve stimulation.10. Addition of noradrenaline (1 x 10(-4) g/ml.) to the ganglion side of the bath reduced but never abolished the amplitude of the synaptic potentials of colonic origin.11. It was concluded that in the guinea-pig, the IMG is involved in a peripheral reflex whose afferent limit of this reflex consists of the axons of cholinergic neurones within the wall of the colon. Many of these neurones are driven either directly or indirectly by cholinergic synapses. The efferent noradrenergic neurones of the IMG function as a group of inhibitory neurones which depress the activity of the excitatory neurones of the colon which are driving them.

Action Potentials↗