Biomedical subjects
Publications and source records attributed to N Shoji.
An amide (dehydropipernonaline) that has coronary vasorelaxant activity was isolated from the fruit of Piper longum L. This substance was characterized on the basis of spectroscopic data.
6-Tridecylresorcylic acid (TRA) isolated from a primula Lysimachia japonica Thunb. inhibited contraction of myofibrils, superprecipitation of myosin B, and ATPase activities of myosin and actomyosin prepared from rabbit skeletal muscle in a dose-dependent manner. The IC50 values in molarity of TRA were as follows: myosin (K+,EDTA)-ATPase, 3.5 X 10(-6); myosin Ca2+-ATPase, 3.5 X 10(-5); and actomyosin Mg2+-ATPase, 1.6 X 10(-5). The inhibition of ATPase activity of myofibrils by TRA was virtually reversed by washing with the fresh saline solution. Kinetic analysis of inhibitory effects of TRA suggests that the inhibition of (K+,EDTA)-ATPase activity of myosin or subfragment-1 is parabolic noncompetitive. TRA had no effect on alkaline phosphatase and choline acetyltransferase activities. TRA may provide a useful chemical tool for the study of the molecular mechanisms of actin-myosin contractile systems.
A crude methanolic extract of the fruit of Nandina domestica Thunberg strongly inhibits serotonin-induced contractions of the rabbit aorta. The extract of the fruit has been fractionated to afford nantenine (O- methyldomesticine ) as the active agent.
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We assessed the function of Endothelin-1 (ET-1) in the development of anterior chamber inflammation in pigmented rabbit eyes. After the injection of ET-1 solution (10(-13), 10(-11), 10(-9), or 10(-7) M, diluted with 300 microL of artificial aqueous humor) into the anterior chamber, the aqueous protein concentration (APC) increased significantly in a dose-dependent fashion. Peak effects were observed 1-2 hours posttreatment. The APC returned to normal 12 hours after the injection. Pretreatment with antiprostaglandin agents, topical indomethacin, or intravenous diclofenac sodium suppressed the increase in APC. In an endotoxin-induced experimental uveitis model, the ET-1 concentration in the aqueous humor was significantly higher than in normal controls, as was the plasma ET-1 level. These results suggest that ET-1 is an important mediator in ocular inflammatory reactions via arachidonic acid cascade.
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