Objective Diverticular bleeding is the most common cause of acute lower gastrointestinal bleeding, and its incidence has recently increased. However, the treatment strategy of diverticular bleeding has not yet been established. The aim of the study was to investigate the efficacy of contrast-enhanced computed tomography (CECT) to determine the indication for urgent colonoscopy to achieve hemostasis. Methods A total of 124 patients diagnosed with diverticular bleeding between 2012 and 2013 in our hospital were analyzed. The clinical behavior, factors related to detecting bleeding diverticula, and risk factors for early rebleeding of diverticular bleeding were evaluated. Results Clinical behavior: Bleeding diverticula were identified in 23 of 124 (19%) patients and most of them (16/23; 70%) were located in the ascending colon. Hemostasis was achieved in all 23 cases, however, six (26%) developed early rebleeding. Factors for detecting bleeding diverticula: In patients in whom extravasation was detected using CECT, the endoscopic detection rate of bleeding diverticula was 60% (12/20), while bleeding diverticula were detected in only 31% (11/35) of patients in whom extravasation was not detected using CECT (p<0.05). The interval between the first hematochezia and colonoscopy in which the bleeding point was detected by colonoscopy (median 23.5 hours) was shorter than that in which bleeding diverticula were not detected (median 43.6 hours) (p<0.01). Risk factors for short term rebleeding: Using a univariate analysis, atherosclerotic comorbidity, anti-inflammatory drugs including low-dose aspirin, antithrombotic agents, vital signs on admission, hemoglobin level on hospitalization, and extravasation on CECT were not found to be significant risk factors. Conclusion The finding of extravasation on CECT is the most important factor for identifying and treating bleeding diverticula by colonoscopy. In such cases, urgent colonoscopy is recommended.
Although vitamin C is considered to act both as pro-oxidant and antioxidant, the mechanisms underlying these actions are still unclear. Using the oxygen-sensitive system of a strict anaerobe, Prevotella melaninogenica, we investigated both the pro-oxidant and antioxidant mechanisms of vitamin C. In the presence of vitamin C, the 8-hydroxydeoxyguanosine (8OHdG) formation induced by oxygen exposure was enhanced, probably due to the action of vitamin C on hydrogen peroxide generated during oxygen exposure: while catalase almost completely suppressed the enhancing effect of vitamin C, 8OHdG formation induced by hydrogen peroxide was enhanced by vitamin C. By contrast, the presence of vitamin C inhibited bacterial cell death, membrane damage, and lipid peroxidation induced by oxygen exposure. Sodium azide showed similar effects to vitamin C, thus the antioxidant action of vitamin C may be due to its quenching of the singlet oxygen generated in this system. Both the pro-oxidant and antioxidant effects of vitamin C were observed only in acidic conditions.
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