PubMed · 61550
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D Greenwood, F O'Grady. 1976-10-16. Mecillinam.. https://doi.org/10.1016/s0140-6736(76)91265-4
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The mechanisms by which endothelin-1 (ET-1) acts on polymorphonuclear leukocytes (PMN) are insufficiently known. In this study, we assessed the hypotheses that ET-1 is a PMN-aggregating agent, and that platelet-activating factor (PAF) is the principal mediator of ET-1-induced PMN aggregation. ET-1 induced dose-related PMN aggregation, which started 1 min after ET-1 exposure. Two different specific PAF receptor antagonists blocked the effect of ET-1 on PMN aggregation. In addition, ET-1 induced a significant increase in the production of PAF by PMN after 2 to 5 min of ET-1 incubation. ET-1 induced PAF release from PMN rather than accumulation. This PAF production was dependent on intra- and extracellular Ca2+. In this regard, the PAF receptor antagonists significantly blunted the ET-1-induced peak in cytosolic free Ca2+ ([Ca2+]i). Our results, therefore, indicate that ET-1 is effective in causing aggregation of human PMN and that its action appears to be mediated by PAF production via a Ca(2+)-dependent mechanism.
The performance of aeration, photodecomposition and biological degradation processes as methods to reduce molinate contamination levels in effluent water from rice fields was studied. Aeration produced a molinate dissipation of 84%, as against 22% without aeration. Application of UV-light to clean water solutions achieved a molinate photodecomposition of 96% in 24 h. Maximal degradation obtained in algal cultures was 55% in 20 days and 78% in 40 days. In micro-organism cultures, kept in darkness and with a continuous flow of aqueous solution of molinate and inorganic salts, a degradation of 97% was achieved.
We prepared anti-platelet 20-kDa myosin light chain (MLC-20) antibody and demonstrated diphosphorylation of MLC-20 in platelets ex vivo in the initial phase of activation by thrombin. Our results are as follows. (1) By Western blotting, using anti-MLC-20 antibody, both mono- and diphosphorylated myosin were seen in the initial phase of aggregation of platelets by thrombin. The peak of the diphosphorylation was later than that of monophosphorylation and the degree of both mono- and diphosphorylation reduced in the process of aggregation. (2) ML-7 (a synthetic inhibitor of MLCK) inhibited both mono- and diphosphorylation of myosin and also blocked aggregation of thrombin-activated platelets. However, H-7 (an inhibitor of protein kinase C) had little effect on either the (di)phosphorylation of myosin or the aggregation of thrombin-activated platelets. (3) Arg-Gly-Asp-Ser (RGDS) peptide, a synthetic anti-adhesive peptide, inhibited aggregation of thrombin-activated platelets in a dose-dependent manner (100-200 microM). However, it had little effect on either mono- or diphosphorylation of myosin in the process of the platelet aggregation stimulated by thrombin. From these results, we conclude that mono- and diphosphorylation of myosin by MLCK play a role in the initial phase of activation of thrombin-stimulated platelets in vivo and that mono- and diphosphorylation of myosin by MLCK precedes the secondary signal mediated by GPIIb/IIIa.