Long-term outcome of patients with distal ulcerative colitis and inflammation of the appendiceal orifice

Effect of γ-aminobutyric acid on isolated colonic smooth muscle from rats with experimental ulcerative colitis

AIM: To assess the effect of γ-aminobutyric acid (GABA) on isolated colonic smooth muscle from rats with experimental ulcerative colitis (UC).

METHODS: Seventeen Wistar rats were randomly divided into either a normal group (six rats) or a model group (eleven rats). The normal group was given distilled water, while the model group was given distilled water containing 3% dextran sulfate 5000. The body mass of the rats and the character of the stool were observed every day, and the disease active index (DIA) was scored. Nine days later, all the rats were killed to observe the changes of the gross morphology and the pathologic changes of the colon under a microscope by taking tissue specimens from serious lesion sites for HE staining. Meanwhile, colonic smooth muscle was isolated to observe the effect of muscimol, a receptor agonist of the GABA and GABA_A, bicuculline, an antagonist of the GABA_A, and baclofen, a receptor antagonist of the GABA_B on the isolated colonic smooth muscle using isometric tension as an indicator.

RESULTS: After four days of treatment with dextran sulfate 5000, the character of the stool of rats in the model group changed, with 30% of rats showing loose stool and 70% showing diarrhea. After six days, about 40% of rats had obvious bloody stool and an obvious decrease in activity and eating. In rats of the normal group, gross pathological examination revealed that the colon had no adhesion, the mucosa had mild hyperemia but no ulcers; microscopic pathological examination revealed intact tissue structure and regularly arranged glands. In rats of the model group, the number of glands decreased, the tissue structure was disorderly, the mucosa was erosive, bleeding, necrotic, and had large deep ulcers. Compared with the normal group, the DIA (3.83 ± 2.74 vs 1.23 ± 1.62, P < 0.05) and histopathologic score (2.52 ± 1.36 vs 0.41 ± 0.74, P < 0.05) were increased significantly in the model group. Treatment with GABA significantly inhibited the independent contraction activities of the isolated colonic smooth muscle from rats of both the normal and model groups (P < 0.05). Treatment with GABA at 0.01 mmol/L and 100 mmol/L resulted in inhibition rates of 20.00% ± 0.02% and 67.60% ± 0.03%, respectively, for the normal group, and 19.50% ± 0.02% and 64.50% ± 0.05% for the model group. There were no significant differences in the above inhibition rates between the two groups (P > 0.05). Treatment with 0.01 mmol/L bicuculline increased the contractile tension of the isolated colonic smooth muscle of the rats (1.25 g ± 0.03 g vs 0.77 g ± 0.04 g, P < 0.05), but treatment with 0.01 mmol/L muscimol or 0.01 mmol/L baclofen decreased the contractile tension significantly (0.38 g ± 0.03 g vs 0.75 g ± 0.06 g, P < 0.05; 0.45 g ± 0.05 g vs 0.75 g ± 0.04 g, P < 0.05).

CONCLUSION: GABA has inhibitory effects on the contraction of the isolated colonic smooth muscle of rats. There exist GABA_A and GABA_B in the isolated colonic smooth muscle of rats, and GABA has inhibitory effects on the muscle contraction when acting on GABA_A, but has stimulating effects when acting on GABA_B.

Meta-analysis: serological markers and the risk of acute and chronic pouchitis

BACKGROUND

Serological markers such as anti-neutrophil cytoplasmic antibody (ANCA) and anti-Saccharomyces cerevisiae antibody (ASCA) may be associated with pouchitis after ileal pouch-anal anastomosis (IPAA).

AIM

To perform a systematic review with meta-analysis of studies evaluating the association of ANCA and ASCA status with risk of acute and chronic pouchitis after IPAA.

METHODS

We searched multiple databases (upto September 2012) for studies reporting ANCA and/or ASCA status along with risk of acute or chronic pouchitis after IPAA in adults with ulcerative colitis (UC). We abstracted odds ratio (OR) or raw data from the individual studies to calculate summary OR estimates with 95% CIs using random-effects model.

RESULTS

Eight studies reporting 184 cases of acute pouchitis and six studies reporting 151 cases of chronic pouchitis were included. The odds of chronic pouchitis were 76% higher in ANCA-positive patients than ANCA-negative (six studies; OR: 1.76; 95% CI: 1.19-2.61; P < 0.01). ASCA-positivity was not associated with the risk of chronic pouchitis (three studies; OR: 0.89; 95% CI: 0.49-1.59; P = 0.68). Neither ANCA (eight studies; OR: 1.54; 95% CI: 0.79-3.02; P = 0.21) nor ASCA-positivity (two studies; OR: 1.28; 95% CI: 0.25-6.54; P = 0.77) were associated with the risk of acute pouchitis.

CONCLUSIONS

The risk of chronic pouchitis after IPAA is higher in ANCA-positive patients, but the risk of acute pouchitis is unaffected by ANCA status. ASCA status was not associated with the risk of acute or chronic pouchitis. This information may be used to counsel UC patients regarding their risk of pouchitis after IPAA.

Inflammatory bowel disease

Although ulcerative colitis and Crohn's disease are relatively uncommon disorders, most primary care practices include a number of individuals with these diagnoses. Much of the initial evaluation and long-term care of these patients is managed or coordinated by their primary care physicians. A familiarity with current principles of diagnosis and treatment is essential. Ulcerative colitis and Crohn's disease are related, immunologically mediated disorders of unknown cause. Both are characterized by chronic relapsing courses, frequent need for surgical intervention, and increased colorectal cancer risk. Significant differences are seen between these two inflammatory bowel disease syndromes, in their histopathologic features, clinical manifestations, and response to treatment. This review focuses on the colorectal manifestations of inflammatory bowel disease, emphasizing clinical presentation, approach to diagnosis, medical and surgical management, and long-term prognosis.