Studies on new platelet aggregation inhibitors 1. Synthesis of 7-nitro-3,4-dihydroquinoline-2(1H)-one derivatives.

A series of 6-cyclic aliphatic amino-7-nitro-3,4-dihydroquinoline-2(1H)-ones were prepared and tested for platelet aggregation inhibitory effect, cardiotonic activity and chronotropic activity. These compounds appeared to show selective inhibitory activity against platelet aggregation. Among them, 6-(4-ethoxycarbonylpiperidino)-7-nitro-3,4-dihydroquinoline-2(1H)-one (22f) showed the most potent inhibitory activity and high selectivity. A divergent synthetic route to 6-cyclic aliphatic amino-7-nitro-3,4-dihydroquinoline-2(1H)-one derivatives has also been investigated.

[A case report of closing aortic dissection with cardiac tamponade which developed re-dissection three weeks later].

A 57-year-old female with hypotension and consciousness disturbance was referred to our institute. Echocardiography and plain CT revealed cardiac tamponade, but no apparent evidence of aortic dissection was obtained. With sudden onset of hypotension, she was immediately operated without information of aortography, enhanced CT, and MRI. Approximately 200 g of pericardial hemorrhage and slight subadventitial hematoma was grossly found and surface ultrasonography revealed the mild localized intramural hematoma (crescent-shaped translucent layer of at most 5 mm in width) at the proximal ascending aorta. Because neither false lumen with blood flow nor intimal flap was found, pericardial drainage without aortic replacement was performed. However, DeBakey type II of aortic dissection with wide false lumen was found with CT and MRI within three weeks, and re-operation was carried out. The dissection ranged from the ostium of right coronary artery to the beginning of innominate artery, but did not involve the coronary arteries and major branches of aortic arch. The surface ultrasonography and transesophageal echocardiography, as well as preoperative CT and MRI, demonstrated that false lumen was thrombosed except at the anterior aspect of mid-portion of ascending aorta. The ascending aorta was replaced. A careful follow-up is mandatory for even a localized intramural hematoma, which can progress into aortic dissection in a short period.

Frictional forces and surface topography of a new ceramic bracket.

The present study was designed to measure the frictional forces between orthodontic wires and a new ceramic bracket and to investigate the differences in the frictional forces with the new and two previously available ceramic brackets. Frictional forces were measured during the sliding of 0.016 x 0.022-inch and 0.017 x 0.022-inch cobalt-chromium alloy wire through three brackets bonded to a simulated tooth. The wires were not ligated into the brackets, so as to eliminate the influences of ligation on the bracket-wire friction. Further, slot surfaces of the three brackets were examined by scanning electron microscope (SEM). The magnitude of frictional forces produced by the new ceramic bracket was significantly less for both the wires than that produced by the two ceramic brackets at 1% level of confidence. The frictional forces with all the brackets exhibited a slight increase as the wire size became larger. The magnitude of frictional forces decreased substantially as the retraction point shifted more cervically. Slot surfaces of the new ceramic bracket were substantially smoother than those surfaces of the two other ceramic brackets. It is shown that refinements of slot surfaces of the ceramic bracket may be effective to reduce friction, although the bracket-wire frictions in this in vitro study were somewhat underestimated because of the lack of ligation of the wire into the bracket.