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Biomedical subjects

Y Masui

Publications and source records attributed to Y Masui.

131 records · Page 8Linked to original sources
PubMedDate not supplied

A randomized trial of aspirin versus cilostazol therapy after successful coronary stent implantation.

Percutaneous transluminal coronary angioplasty (PTCA) is widely used to treat patients with ischemic heart disease, but the procedure involves a number of problems, including acute coronary occlusion and restenosis. Although stents have proved useful for preventing post-PTCA restenosis, especially elastic recoil during the acute phase, no method has yet been established to prevent restenosis caused by vascular smooth muscle cell proliferation in the late phase. Cilostazol selectively inhibits the 3'5'-cyclic-nucleotide phosphodiesterase (PDE) III (cyclic guanosine monophosphate-inhibited PDE) of the cyclic adenosine monophosphate PDE family; it also has antithrombotic and vasodilating effects, as well as an inhibitory effect on vascular smooth muscle cell proliferation through PDE III inhibition. From November 1995 to March 1997, the usefulness of cilostazol versus aspirin in preventing subacute thrombosis and restenosis was studied in 70 patients (55 men and 15 women; 82 total lesions) who had undergone successful elective Palmaz-Schatz stent implantation. Patients were randomly allocated to receive aspirin 81 mg/d (40 patients with 45 lesions) or cilostazol 200 mg/d (30 patients with 37 lesions) alone. There was no difference in patients or angiographic characteristics between these groups. No subacute thrombosis, acute complications (ie, death, emergent coronary artery bypass grafting, or hemorrhagic complications), or drug side effects were found in the cilostazol group. The minimal lumen diameter (mean +/- SD) at follow-up was 1.89 +/- 1.08 mm in the aspirin group (41 lesions, 5.63 +/- 1.74 months after stent implantation) and 2.34 +/- 0.74 mm in the cilostazol group (35 lesions, 5.14 +/- 1.91 months after stent implantation), revealing statistically significant dilatation in the cilostazol group. The restenosis rate was 26.8% in the aspirin group, compared with 8.6% in the cilostazol group; this difference was statistically significant. Administration of cilostazol alone after the implantation of intracoronary Palmaz-Schatz stents was useful for the prevention of subacute thrombosis and restenosis.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Noninvasive estimation of cardiac systolic function using continuous-wave Doppler echocardiography in dogs with experimental mitral regurgitation.

OBJECTIVE: To evaluate the feasibility of noninvasive estimation of cardiac systolic function using transthoracic continuous-wave Doppler echocardiography in dogs with mitral regurgitation. PROCEDURE: Seven mongrel dogs with experimental mitral regurgitation were used. Left ventriculography and measurement of pulmonary capillary wedge pressure were performed under inhalational anaesthesia. A micromanometer-tipped catheter was placed into the left ventricle and transthoracic echocardiography was carried out. The peak rate of left ventricular pressure rise (peak dP/dt) was derived simultaneously by continuous-wave Doppler and manometer measurements. The Doppler-derived dP/dt was compared with the catheter-measured peak dP/dt in the dogs. RESULTS: Classification of the severity of mitral regurgitation in the dogs was as follows: 1+, 2 dogs; 2+, 1 dog; 3+, 2 dogs; 4+, 1 dog; and not examined, 1 dog. We were able to derive dP/dt from the transthoracic continuous-wave Doppler echocardiography in all dogs. Doppler-derived dP/dt had a significant correlation with the catheter-measured peak dP/dt (r = 0.90, P < 0.0001). CONCLUSION: It was demonstrated that transthoracic continuous-wave Doppler echocardiography is a feasible method of noninvasive estimation of cardiac systolic function in dogs with experimental mitral regurgitation and may have clinical usefulness in canine patients with spontaneous mitral regurgitation.

Animals↗
PubMedDate not supplied

Towards understanding the control of the division cycle in animal cells.

The author reviewed the historical process by which classical knowledge of cell division accumulated, to give rise to the molecular biology of the cell cycle, and discussed the perspective of this field of research. The study of the control of cell division began at the turn of the century. It was hypothesized that cell division was a physiological regulation necessary for growing cells to maintain a proper nucleocytoplasmic ratio to survive, which was later substantiated by the finding that amoeba cells could be prevented from dividing by repeated excision of the cytoplasm. However, the observation in Tetrahymena that heat-shocked cells grow exceedingly, but fail to divide, suggested that the cell required the accumulation of a labile "division protein" to initiate division. Mechanisms that control the cell cycle were studied in oocytes by nuclear transplantation and cytoplasmic transfer, and in cultured mammalian cells, protozoa, and Physarum plasmodia by cell fusion. These experiments demonstrated the existence of cytoplasmic factors that control the cell cycle. Maturation promoting factor (MPF) thus discovered in frog oocytes became known to be an ubiquitous cytoplasmic factor that causes the transition from interphase to metaphase in all organisms. The insight into the molecular control of cell growth and division was gained from yeast cell genetics. For biochemical analysis of the cell cycle control, the method to observe the cell cycle in vitro was developed using frog egg extracts. Thus, MPF was identified as a cdc2--cyclin protein complex. Its activity was found to depend on synthesis and phosphorylation of these proteins. However, recently it was found that there were cell cycle phenomena that were difficult to explain in these terms. Various other cellular factors, including nucleocytoplasmic ratio and microtubule assembly, were also found to control MPF, as well as the cell cycle. It remained open to future how these factors control MPF to alter the pattern of the cell cycle.

Animals↗