Showing papers by "Rhône-Poulenc published in 1991"

Experimental Antitumor Activity of Taxotere (RP 56976, NSC 628503), a Taxol Analogue

Abstract: Taxotere (RP 56976; NSC 628503; N-debenzoyl-N-tert-butoxycarbonyl-10-deacetyl taxol) is a new microtubule stabilizing agent. It is obtained by semisynthesis from a noncytotoxic precursor extracted from the needles of the tree, Taxus baccata L. Taxotere was evaluated for antitumor activity against a variety of transplantable tumors of mice. Taxotere had no marked schedule dependency and was found active by the i.v. and the i.p. routes. Upon i.v. administration, 9 of 11 tumor models tested responded to Taxotere. B16 melanoma was found highly sensitive to Taxotere, with a tumor growth inhibition of 0% and a 3.0 log10 tumor cell kill at the maximum tolerated dose. In the same trial, taxol produced only a 1.1 log10 tumor cell kill at the maximum tolerated dose. Taxotere cured early stage pancreatic ductal adenocarcinoma 03 (6 of 6 cures) and colon adenocarcinoma 38 (7 of 7 cures). It also effected greater than 80% complete regressions of advanced stage disease with both tumors. Taxotere was active against early and advanced stage colon adenocarcinoma 51, with 2.3 and 1.7 log10 cell kill, respectively. Four other tumors responded to a lesser extent: Lewis lung (5.5% tumor growth inhibition), Glasgow osteogenic sarcoma (27.2% tumor growth inhibition), L1210 and P388 leukemias (70 and 54% increase in life span, respectively). Because of its good preclinical activity and its unique mechanism of action, Taxotere has entered Phase I clinical trials.

Pharmacological properties of a potent and selective nonpeptide substance P antagonist.

Abstract: We describe here the pharmacological properties of RP 67580 [(3aR,7aR)-7,7-diphenyl-2-[1-imino-2-(2-methoxyphenyl)ethyl] perhydroisoindol-4-one], a nonpeptide antagonist of substance P (SP). In vitro, the compound was found to inhibit in a competitive manner (Ki = 4.16 +/- 0.59 nM) [3H]SP binding to neurokinin receptors type 1 (NK1 receptors) in rat brain membranes. Contractions induced by SP and septide (a selective NK1 agonist) in guinea pig ileum were competitively inhibited by RP 67580 (pA2 = 7.16 and 7.59, respectively). Moreover, RP 67580 displayed the profile of a specific antagonist of NK1 receptors: it was not active on NK2 and NK3 receptors as seen in binding assays and in isolated preparations of rabbit pulmonary artery and rat portal vein. In the rat, low intravenous doses of RP 67580 totally inhibited the plasma extravasation induced by SP in the urinary bladder (ED50 = 0.04 mg/kg i.v.) and by antidromic electrical stimulation of the saphenous nerve in the hind paw skin (ED50 = 0.15 mg/kg i.v.). This compound was also active in two classical analgesic tests in mice: phenylbenzoquinone-induced writhing (ED50 = 0.07 mg/kg s.c.) and the formalin test (ED50 = 3.7 mg/kg s.c.). Its potency was of the same order as that of morphine. Thus we conclude that RP 67580, a SP antagonist, belongs to a class of drugs that may be useful in the management of various clinical pathologies where pain and neurogenic inflammation are involved.

Riluzole specifically blocks inactivated Na channels in myelinated nerve fibre.

Abstract: The effects of 0.15–250 μM riluzole, a novel psychotropic agent with anticonvulsant properties, were studied on voltage-clamped nodes of Ranvier of isolated nerve fibres of the frog. When added to the external solution, the drug rapidly and reversibly inhibited both K and Na currents with an apparent dissociation constant of 0.09 mM. The riluzole-induced decrease of these currents was not “use-dependent”. At concentrations up to 100μM, the drug had no noticeable effect on the time course of Na current inactivation nor on the shape and the position along voltage axis of the Na conductance/voltage relationship. On the other hand, it induced substantial shifts towards negative voltages of the steady-state Na inactivation/voltage curve. From these results, according to the modulated-receptor model, an apparent dissociation constant of 0.29 μM could be calculated for riluzole-induced blockage of inactivated Na channels. The recovery from Na current inactivation was also affected by the drug. It is concluded that riluzole is a highly specific blocker of inactivated Na channels, which is more than 300 times more effective on these channels than on K or resting Na channels.

Stable multicopy vectors for high-level secretion of recombinant human serum albumin by Kluyveromyces yeasts.

Abstract: We have designed stable pKD1 derivatives for efficient secretion of recombinant human serum albumin (rHSA) by industrial strains of Kluyveromyces yeasts. A comparison of this multi-copy expression system with isogenic cassettes integrated at chromosomal loci demonstrated that high level secretion of rHSA is a function of gene dosage in K. lactis. Various signal sequences could be used, and the secretion levels were independent of the presence of the native pro peptide. The mitotic stability of the pKD1-based expression vectors was found to be species and strain dependent and was influenced by promoter strength and culture conditions. Vector stability was drastically enhanced when the HSA gene was expressed from an inducible promoter: 90% of the transformed cells still harbored the vector after 100 generations of non-selective growth in uninduced culture conditions. Secretion levels in the range of several grams per liter of correctly folded and processed rHSA were obtained at the pilot scale, thus making the industrial production of pharmaceutical-grade, Kluyveromyces-derived rHSA economically feasible.

Ligand-induced transphosphorylation between different FGF receptors.

Abstract: Recent evidence shows that different fibroblast growth factors (FGF) bind with similar high affinities to two FGF receptors (FGFR) called flg and bek. In order to explore the mechanism of FGFR tyrosine autophosphorylation, we have generated cell lines which co-express a kinase-negative mutant of FGFR and an active form of FGFR. The following transfected NIH 3T3 cells were generated: (i) cells which express a shorter truncated form of bek (two Ig domains) together with a kinase-negative mutant of full length bek (bek K517A), (ii) cells which express wild-type bek together with kinase-negative flg (flg K514A) and (iii) cells co-expressing wild-type flg together with bek K517A. Immunoprecipitations with either bek-or flg-specific antisera followed by immunoblotting indicated that the double transfectants express the desired receptor species. The addition of acidic FGF (aFGF) to the various cell lines followed by immunoprecipitation with anti-FGFR antibodies and immunoblotting with anti-phosphotyrosine specific antibodies indicated that aFGF induces tyrosine phosphorylation of the kinase-negative FGFR mutants. These results show that tyrosine autophosphorylation of the kinase-negative FGFR is mediated by a transphosphorylation mechanism and that both homologous (bek----bek) and heterologous (bek----flg and flg----bek) transphosphorylation occurs in living cells. Recent evidence shows that tyrosine autophosphorylation of receptors with tyrosine kinase activities is essential for mediating interactions with signaling molecules. Therefore, heterologous transphosphorylation could amplify the response of cells to various forms of FGFs and their cognate receptors.

Bridging of colloidal particles through adsorbed polymers

Abstract: Colloidal silica particles have been dispersed in an aqueous solution of poly(ethylene oxide) macromolecules. The macromolecules adsorb on the silica surfaces and modify the interactions between silica particles. The outer thickness of the adsorbed polymer layers has been determined from changes in the viscosity of the dispersion. Forsaturated layers on large particles this thickness equals the free solution radius of the macromolecules; with small particles the volume of the polymer shell is the same, and the thickness is reduced accordingly.Unsaturated layers are collapsed on the particle surfaces; when such unsaturated layers extend beyond the range of electrostatic repulsions they cause the particles to flocculate.

Fibroblast growth factor receptors

Abstract: The complete cDNA cloning of two human genes previously designated flg and bek is disclosed. These genes encode for two similar but distinct surface receptors comprised of an extracellular domain with three immunoglobulin-like regions, a single transmembrane domain, and a cytoplasmic portion containing a tyrosine kinase domain with a typical kinase insert. The expression of these two cDNAs in transfected NIH-3T3 cells led to the biosynthesis of protein of 150 kDa and 135 kDa for flg and bek respectively. Direct binding experiments with radiolabeled acidic FGF (aFGF), basic FGF (bFGF), or kFGF inhibition of binding with native growth factors, and Scatchard analysis of the binding data indicated that bek and flg bind aFGF, bFGF, or kFGF with dissociation constants of (2-15) × 10 -11 M. The high affinity binding of three distinct growth factors to each of two different receptors represents a unique double redundancy without precedence among polypeptide growth factor/receptor interactions. The use of transformed host cells overexpressing flg or bek or biologically active fragments thereof for drug screening is disclosed.

Tyrphostins inhibit PDGF-induced DNA synthesis and associated early events in smooth muscle cells.

Abstract: Tyrphostins are low-molecular-weight synthetic inhibitors of protein tyrosine kinase, which block cell proliferation. Since platelet-derived growth factor (PDGF) is thought to figure prominently in disorders of vascular smooth muscle cells (VSMC), such as atherosclerosis, hypertension, and restenosis, we examined whether tyrphostins would inhibit PDGF-induced mitogenesis in VSMC. In this communication, we demonstrate that tyrphostins with the benzenemalononitrile nucleus inhibited PDGF-dependent growth of VSMC as well as PDGF-dependent DNA synthesis in these cells, with the concentrations for 50% inhibition ranging from 0.04 to 9 microM. Up to 30-fold higher tyrphostin concentrations were required to inhibit serum-stimulated DNA synthesis of VSMC. The effect of the tyrphostins is reversible, since on their removal a normal proliferative response to PDGF was resumed. Tyrphostins also inhibited PDGF-receptor autophosphorylation and PDGF-induced phosphorylation of intracellular substrates, including the phosphorylation of phospholipase C-gamma, with a potency ratio similar to their antimitogenic activity. The expression of c-fos mRNA, a mitogenic nuclear signal, was also reduced in PDGF-stimulated VSMC treated with tyrphostins at concentrations which inhibit PDGF-induced mitogenesis. It is concluded that tyrphostins are potent reversible inhibitors of PDGF-induced mitogenesis which act by inhibiting the tyrosine kinase activity of the PDGF receptor and the subsequent signaling cascade. Tyrphostins may be useful in the study and treatment of VSMC proliferation disorders.

Material effects in fretting wear : application to iron, titanium, and aluminum alloys

Abstract: Fretting wear tests were performed on several alloys (low alloyed and stainless steels, Ti6A14V titanium alloy, 2024 and 7075 aluminum alloys) slid against themselves in air under relatively low stresses for various displacements (±15 to ±50 μm). Friction logs, where tangential force is plotted as a function of displacement and number of cycles, were used to characterize the fretting behavior of the materials. Wear scars and cross sections were characterized by optical and scanning electron microscopy. Depending on the amplitude of displacement, sticking, partial slip, or gross slip occurs at the interface. Gross slip leads to debris formation. Metallic particles are detached from localized, very highly deformed areas whose properties and structures are different from those of the initial material. Sticking is observed on titanium and aluminum alloys tested under the smallest displacement. Samples are only deformed elastically. During partial slip, cracks can initiate and propagate in titanium and aluminum alloys. Millimeters-long cracks are observed on aluminum alloys after 106 cycles. Mechanisms for crack formation and propagation are described in terms of fatigue properties.

Method for preparing taxane derivatives, novel derivatives thereby obtained and pharmaceutical compositions containing same

Abstract: A method for preparing taxane derivatives having general formula (I), novel derivatives thereby obtained and compositions containing same. In general formula (I), R is t.butoxy or phenyl, R1 is hydrogen or acetyl, and Ar is substituted phenyl or optionally substituted α or β-naphthyl. These novel taxane derivatives are useful as antileukemic and antitumoral agents.

Modulation of interleukin-1 and tumor necrosis factor expression by β-adrenergic agonists in mouse ameboid microglial cells

Abstract: Brain macrophages (ameboid microglial cells) purified to homogeneity and cultured in vitro synthesize and release IL-1 and TNF upon stimulation with lipo-polysaccharide (LPS). This induction can be measured at the levels of transcription and translation. In the present study we have analysed whether certain compounds normally present in the nervous tissue could regulate cytokine production by brain macrophages. We demonstrate that the β-adrenergic agonist isoproterenol, at a concentration of 10-7 M; inhibits the LPS-induced transcription and release of TNFα. At the same concentration, isoproterenol increases the accumulation of IL-1α and IL-1β mRNAs. In spite of its strong effect on IL-1 mRNA accumulation, the adrenergic agonist did not enhance IL-1 activity produced by microglial cells. On the contrary, as is the case for TNF, the LPS-induced production of IL-1 was inhibited by isoproterenol. The effects of isoproterenol on cytokine production specifically involve the β 2 and not the β 1 adrenergic receptor. It thus appears (i) that the accumulation of mRNAs coding for TNFα on one hand and IL-1α and β on the other is regulated in two opposite ways by the stimulation of the β 2-adrenergic receptor and (ii) that mRNA accumulation and cytokine production and secretion are not necessarily coupled.

Styryl-substituted pyridyl compounds which inhibit EGF receptor tyrosine kinase

Abstract: Methods of inhibiting cell proliferation in a patient suffering from such disorder comprising the use of a styryl-substituted heteroaryl compound wherein the heteroaryl group is a monocyclic ring with 1 or 2 heteroatoms, or a bicyclic ring with 1 to about 4 heteroatoms, said compound optionally substituted or polysubstituted, with the proviso that when said ring is polysubstituted, the substituents do not have a common point of attachment to said ring, and those compounds wherein no substituent on the heteroaryl group is a carboxy group or an ester group, and pharmaceutical compositions comprising such compounds.

Process for preparing taxane derivatives, new derivatives obtained and pharmaceutical compositions containing them

Abstract: A method for preparing taxane derivatives having general formula (I), novel derivatives thereby obtained and compositions containing same. In general formula (I), R is t.butoxy or phenyl, R 1 is hydrogen or acetyl, and Ar is substituted phenyl or optionally substituted α or β-naphthyl. These novel taxane derivatives are useful as antileukemic and antitumoral agents. ##STR1##

Recombinant adeno-associated virus vectors

Abstract: A simplified method to produce recombinant adeno-associated virus (AAV) vectors is described. The procedure involves the use of chimeric plasmids which incorporate the Epstein Barr nuclear antigen (EBNA) gene, the latent origin of replication of Epstein Barr Virus (oriP), and a recombinant AAV genome. The chimeric plasmids themselves are also a part of the present invention. These EBV/AAV plasmids are maintained as multicopy extra-chromosomal elements in cells, such as human 293 cells. Permanent cell lines carrying these EBV/AAV plasmids are induced to produce large amounts of recombinant AAV virus upon addition of wild-type, adeno-associated virus helper functions. Recombinant AAV vectors produced in this manner are capable of transducing exogenous genes into other human cell lines and exhibit all of the attributes of viral elements produced by conventional methods.

Compounds having antihypertensive and anti-ischemic properties

Abstract: This invention relates to adenosine derivatives and analogs which possess adenosine agonist activity and are useful as anti-hypertensive and anti-ischemic agents, to pharmaceutical compositions including such compounds, and to their use in treating hypertension and myocardial ischemia, and to methods and intermediates used in the preparation of such compounds.

Insulating shaped articles comprising inorganic fibrous matrices and xanthan gum/cationic starch binders

Abstract: Physically/mechanically improved insulating shaped articles such as panels or plates, adapted to withstand very elevated temperatures, comprise an inorganic fiber matrix, e.g., a matrix of ceramic fibers, such inorganic fiber matrix containing at least one inorganic filler material, e.g., a mineral wool and/or kaolin, and a consolidating of a binder therefor which comprises admixture of a xanthan gum and a cationic starch.

Identification of an RFLP marker tightly linked to theHt1 gene in maize.

Abstract: We have identified tight linkage of an RFLP marker to theHt1 gene of maize that confers resistance to the fungal pathogenHelminthosporium turcicum race 1. This was accomplished by the use of four pairs of near isogenic lines (NILs; B73, A619, W153R, and CM105), each differing by the presence or the absence of the geneHt1. SinceHt1 maps to chromosome 2, 26 clones already mapped to this chromosome were labeled and probed against Southern blots of these NILs DNA digested with three restriction enzymes:EcoRI,BamHI, andHindIII. Six markers exhibited an RFLP for at least one pair of NILs. Presumptive linkage was further tested by analyzing the segregation of five of the six markers (one was monomorphic in the cross studied) and resistance toH. turcicum race 1 on 95 F2 individuals from the cross DF20 × LH146Ht. The results indicate a tight linkage between one of the DNA markers,UMC150B, and theHt1 gene.

Styryl-substituted monocyclic and bicyclic heteroaryl compounds which inhibit egf receptor tyrosine kinase

Abstract: Methods of inhibiting cell proliferation in a patient suffering from such disorder comprising the use of a styryl-substituted heteroaryl compound wherein the heteroaryl group is a monocyclic ring with 1 or 2 heteroatoms, or a bicyclic ring with 1 to about 4 heteroatoms, said compound optionally substituted or polysubstituted, with the proviso that when said ring is polysubstituted, the substituents do not have a common point of attachment to said ring, and those compounds wherein no substituent on the heteroaryl group is a carboxy group or an ester group, and pharmaceutical compositions comprising such compounds.