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Taxomyces andreanae, a fungal endophyte, was isolated from the phloem (inner bark) of the Pacific yew, Taxus brevifolia. The fungus is hyphomyceteous and, when grown in a semi-synthetic liquid medium, produced taxol and related compounds. Taxol was identified by mass spectrometry, chromatography, and reactivity with monoclonal antibodies specific for taxol.(More)
Endophytic microbes associated with the Pacific yew tree, Taxus brevifolia, were examined as potential sources of the anticancer drug taxol [1], a secondary metabolite of the host organism. The first promising organism found was the novel fungus, Taxomyces andreanae, which was isolated from the inner bark of a yew tree growing in northwestern Montana. It(More)
Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10(-5) M; synthetic maculosin possessed chemical and biological(More)
Alkoxy-aryl-lactams (cilostamide, AAL 05, ZK 62 711, Ro 20-1724) inhibit differently cAMP or cGMP phosphodiesterases from blood platelets or vascular smooth muscle. Cilostamide (IC50 0.23 microM) and AAL 05 (IC50 0.15 microM) are 100 times more potent towards platelet cAMP phosphodiesterase whereas ZK 62 711 (IC50 2 microM) and Ro 20-1724 (IC50 33 microM)(More)
Quercetin (3.3',4',5,7-pentahydroxyflavone) has previously been shown to inhibit cyclic nucleotide phosphodiesterases prepared from various cell homogenates and the function of intact human platelets. We now report that (1) high concentrations of quercetin raise platelet cAMP levels; and (2) quercetin potentiates the inhibitory effect of prostacyclin (PGI2)(More)
Extracts of the sponge Tedania ignis have been reported to contain several diketopiperazines. As part of an investigation of the commensal and symbiotic microflora of sponges, we have consistently isolated, from specimens of T. ignis, a Micrococcus sp. which produces diketopiperazines in laboratory cultural media. This is the first demonstration that a(More)
We describe a new variant of Glanzmann's thrombasthenia (variant Strasbourg I). The patient (M.S.) showed an absence of platelet aggregation to ADP, thrombin, and collagen, and a decreased clot retraction. Platelet fibrinogen was approximately 20% of normal levels. ADP-stimulated platelets bound markedly reduced amounts of soluble fibrinogen and platelet(More)
The presence of extracellular ionized calcium (Ca2+) is important to support the aggregation of human blood platelets and for the stability of the platelet fibrinogen receptor, the glycoprotein (GP) IIb-IIIa complex. This study was performed in order to determine the effects of intracellular calcium chelation on human platelet functions, on the expression(More)
The microscopic insight into how and why catalytically active nanoparticles change their shape during oxidation and reduction reactions is a pivotal challenge in the fundamental understanding of heterogeneous catalysis. We report an oxygen-induced shape transformation of rhodium nanoparticles on magnesium oxide (001) substrates that is lifted upon carbon(More)
The thienopyridines, ticlopidine and PCR 4099, inhibit ex vivo aggregation in response to ADP and other agonists. It has been shown that ticlopidine induces a functional defect in the binding of fibrinogen to its platelet membrane receptor. We have studied the effects on platelet functions of PCR 4099 in rat and in man. The aim of the study was to check the(More)