Occludin regulates actin cytoskeleton in endothelial cells.

Occludin is a major membrane component of tight junctions of endothelial cells, though the role of this molecule is not fully understood. RLE cells, derived from rat lung endothelial cells, express a negligible level of occludin with clear expression of E-cadherin and ZO-1 at cell junctions. Introduction of occludin by transfection induced clear junctional expression of occludin with few or no changes of expression of E-cadherin and ZO-1. The paracellular barrier function, as determined by transelectrical resistance and flux of non-ionic small molecules, was not detectably upregulated. When cells expressing occludin were cocultured with RLE cells null for occludin, clear junctional expression of occludin was observed irrespective of the expression of occludin on the apposing cells. Cortical actin was developed at the site of these occludin positive cell junctions. Treatment of cells with an actin depolymerizing agent, mycalolide B, abolished junctional expression of occludin together with E-cadherin and circumferential actin. ZO-1 showed relative resistance to this actin depolymerizing treatment and was maintained at the cell junctions, though fragmentation of immunoreactivity was detectable. Collectively, junctional expression of occludin was not associated with paracellular barrier function in this cell line. There was, however, a close correlation of occludin with the actin cytoskeleton, indicating a role of occludin as an important molecule in the regulation of the actin cytoskeleton in endothelial cells.

Uncoupling of gate and fence functions of MDCK cells by the actin-depolymerizing reagent mycalolide B.

The tight junction serves as a paracellular gate to seal the paracellular space of apposing cells and as a molecular fence to prevent diffusion of membrane proteins and lipids in epithelial cells. Although involvement of the actin cytoskeleton has been considered to be important in these two functions, it remains to be elucidated whether both functions are regulated in a coupled manner or differentially by actin. Treatment of highly polarized MDCK cells with mycalolide B (MB), a recently developed actin-depolymerizing reagent, induced a decrease of transepithelial resistance in a dose- and time-dependent manner with reversibility when the reagent was washed out. Changes in cytoskeletal actin, such as a reduction of cortical actin, irregularity of stress fibers, and punctated actin aggregates, were observed after MB treatment. However, the fence function, as studied by diffusion of apically labeled sphingomyelin/BSA complex, remained intact in the MB-treated MDCK cells. Localization of junctional molecules and apical marker proteins such as E-cadherin, ZO-1, and 114-kDa protein was shown to be unaffected. Furthermore, freeze-fracture study showed apparent tight junction strands. Collectively, MB treatment abolished the paracellular gate but not the fence function of MDCK cells, suggesting that cytoskeletal actin may play differential roles in the gate and fence functions of the tight junction.

[Postoperative sore throat--a comparison of standard cuff, gas-barrier cuff and Brandt anesthesia tube cuff].

Excessive intracuff pressure due to nitrous oxide diffusion into the cuff can damage the tracheal mucosa. Several endotracheal tubes have been developed (Trachelon gas barrier type tube, Brandt Anaesthesia tube) to limit nitrous oxide-related intracuff pressure increase. We investigated whether the incidence of postoperative sore throat could be reduced by using these tubes. Endotracheal intubation was performed in 37 adult female patients with either a standard tube (group S, n = 14), a gas barrier type tube (group G, n = 11), or a Brandt tube (group B, n = 12). All patients were interviewed 16-30 h postoperatively by anesthesiologist who did not know which tube had been used. The increase of intracuff pressure was significantly lower in group G (7.6 +/- 5.1 mmHg, mean +/- SD) and in group B (3.4 +/- 1.7 mmHg) than that in group S (24.0 +/- 9.5 mmHg). The incidence of postoperative sore throat was not significantly different among the groups, 36% (5/14) in group S, 45% (5/11) in group G, and 33% (4/12) in Group B. This incidence did not correlate with intracuff pressure increase. In conclusion, specially manufactured endotracheal tubes to limit excessive intracuff pressure did not effectively attenuate the incidence of postoperative sore throat in this patient population.

[Coronary artery spasm as a cause of perioperative myocardial infarction and stunned myocardium].

We report a male patient who had recurrent coronary artery spasm on withdrawal from cardiopulmonary bypass, which led to myocardial infarction and stunned myocardium. The spasm responded to conventional medication. Transesophageal echocardiogram showed no remarkable asynergy during the operation. However, MB fraction of creatine kinase was 132 IU.l-1 and electrocardiogram showed new Q waves. After stopping intravenous catecholamines, hypokinesis of the anteroseptal segment appeared in the echocardiogram. Spotty myocardial necrosis and stunned myocardium might have resulted from recurrent coronary artery spasm.

[Evaluation of endoscopic local injection of hypertonic saline- epinephrine solution and surgical treatment on hemorrhagic gastroduodenal ulcer].

For the purpose of arresting hemorrhage from gastric and duodenal ulcer we developed a method of endoscopic local injection of hypertonic saline-epinephrine solution (HSE), consisting of 625mEq/L or 1,250mEq/L sodium chloride with 0.05mg/ml epinephrine. During the period between October 1978 and March 1988, a total 246 patients with peptic ulcers underwent treatment for hemostasis by this method. According to our criteria for the assessment of the hemostatic effect, 231(93.9%) of 246 cases achieved permanent hemostasis, 7(2.8%) achieved temporary hemostasis, and no effect was noted 8 cases (3.3%). From June 1975 to March 1988, a total 366 cases with gastric and duodenal ulcers were operated on at our hospital. By applying endoscopic local injection of HSE, the rate of emergency operation for patients with bleeding peptic ulcers was significantly reduced from 13.4%(22/164) to 1.5%(3/202). From these results, we consider that endoscopic local injection of HSE is valuable for hemorrhage from gastric and duodenal ulcer.