Antithrombotic effect of topically applied 3-Oxa-Methano-prostaglandin I1 in the microcirculation and antiplatelet functions of its active form

The antithrombotic effect of topical application of the 3-oxamethano-prostaglandin (PG) I₁ analog, SM-10902 in the microcirculation and in vitro antiplatelet functions of its active form SM-10906 were estimated in comparison with PGI₂ and PGE₁. In rat platelets, SM-10906 evoked accumulation of intracellular cyclic adenosine 3′,5′-monophosphate, and exhibited antiaggregatory and disaggregatory activities, which were all enhanced by the phosphodiesterase inhibitor theophylline. Additionally, SM-10906 was shown to inhibit platelet adhesion to collagen in human platelet-rich plasma. PGI₂ and PGE₁ also showed in vitro antiplatelet effects in the order of PGI₂ > SM-10906 ≥ PGE₁. SM-10902 exhibited a dose-dependent antithrombotic effect in the guinea pig mesenteric arteriole by a topical application, and this activity might be exerted by the antiplatelet functions of SM-10906. Although SM-10906, PGI₂ and PGE₁ also showed the antithrombotic effects, SM-10902 was the most potent. In conclusion, the present studies indicate that an external topical preparation of SM-10902 may be useful for the therapy of peripheral circulatory insufficiency.     

Nitric Oxide-Induced [3H]GABA Release from Cerebral Cortical Neurons Is Mediated by Peroxynitrite

Abstract: The functional significance of peroxynitrite in the release of [³H]GABA induced by nitric oxide (NO) liberated from NO generators was investigated using cerebral cortical neurons in primary culture. NO generators such as sodium nitroprusside (SNP) and S -nitroso- N -acetylpenicillamine (SNAP) increased [³H]GABA release in a dose-dependent manner. These increases in [³H]GABA release were significantly inhibited by hemoglobin, indicating that those NO generators evoke the release of [³H]GABA by the formation of NO. Two types of superoxide scavengers, Cu²⁺/Zn²⁺ superoxide dismutase and ceruloplasmin, significantly reduced the increase in [³H]GABA release induced by both SNP and SNAP, which assumes that NO requires superoxide to induce [³H]GABA release from the neurons. In addition, synthesized peroxynitrite induced a dose-dependent increase in [³H]GABA release from the neurons. These results indicate that NO-induced [³H]GABA release is mediated by peroxynitrite formed by the reaction of NO with superoxide.     

Peroxidation of lipids and growth inhibition induced by UV-B irradiation

Cotyledons excised from dark-grown seedlings of cucumber (Cucumis sativus L.) were cultured in vitro under UV radiation at different wavelengths, obtained by passage of light through cut-off filters with different transmittance properties. Growth and the synthesis of chlorophyll (Chl) in cotyledons were inhibited and malondialdehyde was accumulated upon irradiation at wavelengths below 320 nm. Exogenous application of scavengers of free radicals reversed the growth inhibition induced by UV-B. Measurement of the fluorescence of Chl a suggested that electron transfer in photosystems was affected by UV-B irradiation. On the basis of these results, the involvement is postulated of active species of oxygen in damages to thylakoid membranes and the growth inhibition that are induced by UV-B irradiation.Abbreviations Chl chlorophyll - F_m maximal fluorescence (dark) - F_m maximal fluorescence (light) - F_v variable fluorescence (dark) - F_v variable fluorescence (light) - MDA malondialdehyde - O₂ Superoxide radical - PS photosystem - q_N non-photochemical quenching of fluorescence - q_P photochemical quenching of fluorescence - UV-B_BE biologically effective UV-B radiation - WL(T = 0.5) wavelength at which 50% transmittance occurs     

Yezonia,a new section ofAraucaria (Araucariaceae) based on permineralized vegetative and reproductive organs ofA. vulgaris comb. nov. from the upper cretaceous of Hokkaido,Japan

A new specimen of an araucarian cone,Araucaria nihongii, was found attached to the vegetative organs ofYezonia vulgaris, and is described asAraucaria vulgaris comb. nov. Thick branches show characteristic bark structure with lenticular patches. Secondary wood is usually araucarioid. Leaves are arranged helically on shoots, which are imbricate, appressed and fused to surface of the stem. External and anatomical features of leaves closely resembleBrachyphyllum. The seed cone is spherical with winged bracts and thin ovuliferous scales. One seed is borne per cone-scale complex. The seed coat and nucellus wall show typical araucarian structure. An araucarian plant that boreBrachyphyllum-like foliage and aEutacta-like seed cone was predicted by Harris in 1979. This reconstructed plant,Araucaria vulgaris, supports this theory and proves the presence of an extinct characteristic-form of the genus. A new section of the genus was proposed forAraucaria vulgaris. Structure and Affinities of the Petrified Plants from the Cretaceous of Northern Japan and Saghalien XV, Consecutive number from previous paper (Nishidaet al. 1993).     

Action spectra for the light inhibition of flowering and its reversal inLemna paucicostata T-101

Lemna paucicostata Hegelm. T-101, a short-day plant, flowers when plants preirradiated with red light (R) for 24 h are subjected to inductive darkness for 72 h followed by two short-day cycles (6 h R+ 18 h dark). However, flowering is inhibited by blue-or far-red-light pulses applied at the beginning of the inductive dark period. These inhibitory light effects are fully reversible by a R pulse. The action spectra for the inhibitory light effect and for its reversal show that the light pulses act exclusively through phytochrome. It is concluded that a low level of Pfr at the beginning of the inductive dark period prevents flowering.Abbreviations R red (light) - B blue (light) - FR far-red (light)     

Viomycin favours the formation of 70S ribosome couples

Summary The peptide antibiotic viomycin at a concentration of 10 M inhibits E. coli ribosomes to the extent of about 70% as measured in the poly(U) system, and to about 85% in a natural mRNA (R17) system. Ribosomes from M. smegmatis show no activity at all at this concentration of the antibiotic. Experiments on the Mg²⁺ dependent dissociation and association of the ribosomal subunits revealed that viomycin stabilizes the 70S couples and promotes association of ribosomal subunits. This response is related to the drug action as indicated by the observation that viomycin resistant strains are not affected by viomycin with respect to dissociation and 70S couple information. A model for the inhibitory action of the drug is proposed.     

Excretion of peroxidase from horseradish hairy root in combination with ion supplementation

Summary The effect of ion-supplemented medium on peroxidase excretion from horseradish (Armoracia rusticana) hairy roots was studied. Supplementation of mannitol instead of ions revealed that the excretion was stimulated not by osmotic pressure in the medium but by ionic properties. Extracellular peroxidase activity per dry cell was proportionally correlated with the ionic strength of the cations. CaCl₂ or MgCl₂ was found to be the most effective agent for excretion among other combinations. CaCl₂ supplementation at the beginning of the culture caused higher peroxidase production in the medium without a significant loss of final cell mass compared with CaCl₂ addition during the culture. Repeated batch culture with 50 mM CaCl₂ supplementation allowed a continuous retention of cell viability over 149 days and produced a great amount of extracellular peroxidase, 12-fold higher than that achieved in a 40-day-old batch culture with 50 mM CaCl₂ supplementation. Correspondence to: T. Kobayashi