Gastroenterology
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Case Reports
Toxic megacolon in ulcerative colitis complicated by pneumomediastinum: report of two cases.
We describe two cases of universal ulcerative colitis in which toxic megacolon was complicated by the unusual occurrence of air tracking retroperitoneally through the diaphragm and the mediastinum, without signs of free intraperitoneal air, and ultimately presenting as subcutaneous emphysema in the neck. Physicians should remain alert to this unusual presentation of air leakage from the colon in toxic ulcerative colitis, in order to appreciate the potential gravity of the situation.
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The effect of a period of induced back diffusion of H+ on the isolated amphibian gastric mucosa was studied under various conditions. Under standard conditions (HCO3--buffered nutrient solution; 95% O2-5% CO2), passage of an electrical current of 500 microA/cm2 for 15 min from a secretory fluid of pH 2.10 across the mucosal resulted in a decrease of the transmucosal potential difference (PD) of 10.9 +/- 1.9 mV, a decrease of resistance (R) of 48 +/- 26 ogema cm2 and a decrease of short circuit current (Isc) of 18 +/- 7 microA/cm2. Flux of the neutral molecule, erythritol from secretory (S) to nutrient (N) fluid increased by 66% and the active transport of Cl- N lead to S decreased from 2.9 to 1.9 microeq/cm2/hr. ⋯ This increased effect of back diffusion of H+ was not changed by change of the nutrient fluid pH from 7.20 to either 6.6 or 8.2. Increase of the HCO3- concentration of the nutrient fluid to 35 mM or decrease of the CO2 content of the aerating gas to 1% were associated with significantly less change of the electrical measurements than occurred with standard conditions. These studies support the proposal that the the neutralizing reaction HCO3- + H+ leads to CO2 + H2O plays a central role in the gastric mucosal handling of backing diffusing H+ and suggests that the capacity and poise of the HCO3-/CO2 buffer system is an important determinant of the ability of the mucosa to tolerate luminal acidity.
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A patient is described who sustained the first reported colonic explosion during colonoscopic polypectomy. Mannitol solution was used for bowel preparation, and the colon was completely clean. ⋯ In spite of emergency surgery with transfusion of 45 units of blood, uncontrollable hemorrhage persisted from multiple bleeding points, and the patient died. This occurrence seems to us to justify the routine use of carbon dioxide insufflation during polypectomy and the avoidance of mannitol for bowel preparation.
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Randomized Controlled Trial Clinical Trial
Prophylactic doxycycline for travelers' diarrhea: results of a prospective double-blind study of Peace Corps volunteers in Morocco.
A second randomized double-blind study to determine the efficacy of doxycycline, 100 mg daily, for the prevention of travelers' diarrhea was carried out among 50 Peace Corps Volunteers during their first 10 wk in Morocco. The volunteers took either doxycycline or placebo for 3 wk, and were observed for an additional 7 wk. ⋯ Enterotoxigenic E. coli, most of which were sensitive to doxycycline, were the most frequently isolated pathogens during the entire study. This study corroborates the effectiveness of doxycycline prophylaxis for travelers' diarrhea.