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Showing papers by "Novartis published in 1998"


Journal ArticleDOI
17 Dec 1998-Nature
TL;DR: A new GABAB receptor subtype is described, GABABR2, which does not bind available GABAB antagonists with measurable potency and exhibits a significant increase in agonist- and partial-agonist-binding potencies as compared with individual receptors.
Abstract: B-type receptors for the neurotransmitter GABA (gamma-aminobutyric acid) inhibit neuronal activity through G-protein-coupled second-messenger systems, which regulate the release of neurotransmitters and the activity of ion channels and adenylyl cyclase. Physiological and biochemical studies show that there are differences in drug efficiencies at different GABA(B) receptors, so it is expected that GABA(B)-receptor (GABA(B)R) subtypes exist. Two GABA(B)-receptor splice variants have been cloned (GABA(B)R1a and GABA(B)R1b), but native GABA(B) receptors and recombinant receptors showed unexplained differences in agonist-binding potencies. Moreover, the activation of presumed effector ion channels in heterologous cells expressing the recombinant receptors proved difficult. Here we describe a new GABA(B) receptor subtype, GABA(B)R2, which does not bind available GABA(B) antagonists with measurable potency. GABA(B)R1a, GABA(B)R1b and GABA(B)R2 alone do not activate Kir3-type potassium channels efficiently, but co-expression of these receptors yields a robust coupling to activation of Kir3 channels. We provide evidence for the assembly of heteromeric GABA(B) receptors in vivo and show that GABA(B)R2 and GABA(B)R1a/b proteins immunoprecipitate and localize together at dendritic spines. The heteromeric receptor complexes exhibit a significant increase in agonist- and partial-agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA(B) receptor. Heteromeric assembly among G-protein-coupled receptors has not, to our knowledge, been described before.

1,194 citations


Journal ArticleDOI
01 Oct 1998-Nature
TL;DR: It is shown that a T-cell-specific, SLAM-associated protein (SAP), which contains an SH2 domain and a short tail, acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region.
Abstract: In addition to triggering the activation of B- or T-cell antigen receptors, the binding of a ligand to its receptor at the cell surface can sometimes determine the physiological outcome of interactions between antigen-presenting cells, T and B lymphocytes. The protein SLAM (also known as CDw150), which is present on the surface of B and T cells, forms such a receptor-ligand pair as it is a self-ligand. We now show that a T-cell-specific, SLAM-associated protein (SAP), which contains an SH2 domain and a short tall, acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region. The gene encoding SAP maps to the same area of the X chromosome as the locus for X-linked lymphoproliferative disease (XLP) and we found mutations in the SAP gene in three XLP patients. Absence of the inhibitor SAP in XLP patients affects T/B-cell interactions induced by SLAM, leading to an inability to control B-cell proliferation caused by Epstein-Barr virus infections.

901 citations


Journal ArticleDOI
TL;DR: Evidence is shown that LMB binds directly to CRM1 and thatCRM1 is essential for NES-dependent nuclear export of proteins in both yeast and mammalian cells, and is an essential factor for nuclear exported proteins in eukaryotes.

800 citations



Journal ArticleDOI
TL;DR: The General Practice Research Database in the UK has proved that valuable data can be collected in a general practice setting and should serve to encourage others to develop similar population-based data in other countries.
Abstract: The last decade has seen a surge in the use of computerized health care data for pharmacoepidemiology. Of all European databases, the General Practice Research Database (GPRD) in the UK, has been the most widely used for pharmacoepidemiological research. Since 1994, this database has belonged to the UK Department of Health, and is maintained by the Office of National Statistics (ONS). Currently, around 1500 general practitioners with a population coverage in excess of 3 million, systematically provide their computerized medical data anonymously to ONS. Validation studies of the GPRD have documented the recording of medical data into general practitioners’ computers to be near to complete. The GPRD collects truly population-based data, has a size that makes it possible to follow-up large cohorts of users of specific drugs, and includes both outpatient and inpatient clinical information. The access to original medical records is excellent. Desirable improvements to the GPRD would be additional computerized information on certain variables and linkage to other health care databases. Most published studies to date have been in the area of drug safety. The General Practice Research Database has proved that valuable data can be collected in a general practice setting. The full potential of this rich computerized database has yet to come. This experience should serve to encourage others to develop similar population-based data in other countries.

554 citations


Journal ArticleDOI
15 Oct 1998-Nature
TL;DR: It is shown that presenilin-1 forms a complex with β-catenin in vivo that increases β-Catenin stability, which increases neuronal vulnerability to apoptosis induced by amyloid-β protein.
Abstract: Mutations of the presenilin-1 gene are a major cause of familial early-onset Alzheimer's disease. Presenilin-1 can associate with members of the catenin family of signalling proteins, but the significance of this association is unknown. Here we show that presenilin-1 forms a complex with beta-catenin in vivo that increases beta-catenin stability. Pathogenic mutations in the presenilin-1 gene reduce the ability of presenilin-1 to stabilize beta-catenin, and lead to increased degradation of beta-catenin in the brains of transgenic mice. Moreover, beta-catenin levels are markedly reduced in the brains of Alzheimer's disease patients with presenilin-1 mutations. Loss of beta-catenin signalling increases neuronal vulnerability to apoptosis induced by amyloid-beta protein. Thus, mutations in presenilin-1 may increase neuronal apoptosis by altering the stability of beta-catenin, predisposing individuals to early-onset Alzheimer's disease.

547 citations


Journal ArticleDOI
TL;DR: Data indicate an inhibition of MMP-9 secretion by the drug, mediated by the inhibition of synthesis of mevalonate, a precursor of numerous derivatives essential for several cellular functions.
Abstract: -Macrophages secrete matrix metalloproteinases (MMPs) that may weaken the fibrous cap of atherosclerotic plaque, predisposing its fissuration. The 92-kDa gelatinase B (MMP-9) has been identified in abdominal aortic aneurysms and in atherosclerotic tissues. Fluvastatin, through the inhibition of the isoprenoid pathway, inhibits major processes of atherogenesis in experimental models (smooth muscle cell migration and proliferation and cholesterol accumulation in macrophages). We studied the effect of fluvastatin on the activity of MMP-9 in mouse and human macrophages in culture. Conditioned media of cells treated for 24 hours with fluvastatin were analyzed by gelatin zymography. In mouse macrophages, fluvastatin (5 to 100 micromol/L) significantly inhibited in a dose-dependent manner MMP-9 activity from 20% to 40% versus control. The drug, at a concentration as low as 5 micromol/L, inhibited MMP-9 activity ( approximately 30%) in human monocyte-derived macrophages as well. Phorbol esters (TPA, 50 ng/mL) stimulated MMP-9 activity by 50%, and fluvastatin inhibited this enhanced activity up to 50% in both mouse and human macrophages. The above results on the secretion of MMP-9 were confirmed by Western blotting and ELISA. The inhibitory effect of fluvastatin was overcome by the simultaneous addition of exogenous mevalonate (100 micromol/L), a precursor of isoprenoids. Fluvastatin's effect was fully reversible, and the drug did not cause any cellular toxicity. The statin did not block directly the in vitro activation of the secreted protease. Similar data were obtained with simvastatin. Altogether, our data indicate an inhibition of MMP-9 secretion by the drug. This effect is mediated by the inhibition of synthesis of mevalonate, a precursor of numerous derivatives essential for several cellular functions.

526 citations


Journal ArticleDOI
22 Oct 1998-Nature
TL;DR: It is reported that these mice exhibit selective neuronal death in the brain regions that are most affected in AD, suggesting that amyloid plaque formation is directly involved in AD neuron loss.
Abstract: Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects a large proportion of the elderly population. Amyloid plaques, which are a neuro-pathological characteristic of AD, have been reproduced in transgenic mice by the overexpression of mutant forms of the amyloid-β precursor protein (APP) known to cause familial AD. Here we report that these mice exhibit selective neuronal death in the brain regions that are most affected in AD, suggesting that amyloid plaque formation is directly involved in AD neuron loss.

497 citations


Journal ArticleDOI
09 Apr 1998-Nature
TL;DR: It is found that GluR6-deficient mice are less susceptible to systemic administration of kainate, as judged by onset of seizures and by the activation of immediate early genes in the hippocampus.
Abstract: L-glutamate, the neurotransmitter of the majority of excitatory synapses in the brain, acts on three classes of ionotropic receptors: NMDA (N-methyl-D-aspartate), AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptors. Little is known about the physiological role of kainate receptors because in many experimental situations it is not possible to distinguish them from AMPA receptors. Mice with disrupted kainate receptor genes enable the study of the specific role of kainate receptors in synaptic transmission as well as in the neurotoxic effects of kainate. We have now generated mutant mice lacking the kainate-receptor subunit GluR6. The hippocampal neurons in the CA3 region of these mutant mice are much less sensitive to kainate. In addition, a postsynaptic kainate current evoked in CA3 neurons by a train of stimulation of the mossy fibre system is absent in the mutant. We find that GluR6-deficient mice are less susceptible to systemic administration of kainate, as judged by onset of seizures and by the activation of immediate early genes in the hippocampus. Our results indicate that kainate receptors containing the GluR6 subunit are important in synaptic transmission as well as in the epileptogenic effects of kainate.

475 citations


Journal ArticleDOI
TL;DR: A family of structured oligo-N-substituted-glycines (peptoids) up to 36 residues in length is synthesized and characterized by using an efficient solid-phase protocol to incorporate chemically diverse side chains in a sequence-specific fashion.
Abstract: We have synthesized and characterized a family of structured oligo-N-substituted-glycines (peptoids) up to 36 residues in length by using an efficient solid-phase protocol to incorporate chemically diverse side chains in a sequence-specific fashion. We investigated polypeptoids containing side chains with a chiral center adjacent to the main chain nitrogen. Some of these sequences have stable secondary structure, despite the achirality of the polymer backbone and its lack of hydrogen bond donors. In both aqueous and organic solvents, peptoid oligomers as short as five residues give rise to CD spectra that strongly resemble those of peptide α-helices. Differential scanning calorimetry and CD measurements show that polypeptoid secondary structure is highly stable and that unfolding is reversible and cooperative. Thermodynamic parameters obtained for unfolding are similar to those obtained for the α-helix to coil transitions of peptides. This class of biomimetic polymers may enable the design of self-assembling macromolecules with novel structures and functions.

452 citations


Journal ArticleDOI
TL;DR: The Cholesterol and Recurrent Events (CARE) trial investigated whether reducing average cholesterol levels by using pravastatin in patients who have had myocardial infarction would prevent recurrent cardiac events, and reported that patients who were older than the median age of 59 years had a reduced rate of coronary death, nonfatal myocardIAL infarctions, coronary artery bypass grafting, angioplasty, and stroke.
Abstract: Background: A majority of all myocardial infarctions occur in patients who are 65 years of age or older and have average cholesterol levels, but little information is available on whether cholester...

Journal ArticleDOI
TL;DR: The utility of polymerase chain reaction (PCR)-based markers such as SSRs for measuring genetic diversity, for assigning lines to heterotic groups and for genetic fingerprinting equals or exceeds that of RFLP markers, a property that may prove a valuable asset for a maize breeding program.
Abstract: Among maize (Zea maize L.) breeders, there is a heightened awareness of the necessity for both maintaining genetic diversity for crop improvement and improving the quality of genetic resource management. Restriction fragment length polymorphisms (RFLPs) and isozymes can serve as genetic markers for estimating divergence or diversity ; however, the limited number of polymorphic isozyme loci available and the labor intensive and time consuming nature of RFLPs make their use for this purpose prohibitive. Simple sequence repeats (SSRs), when resolved using agarose gels, may be a viable and cost-effective alternative to RFLPs and isozymes. Ninety-four elite maize inbred lines, representative of the genetic diversity among lines derived from the Corn Belt Dent and Southern Dent maize races, were assayed for. polymorphism at 70 SSR marker loci using agarose gels. The 365 alleles identified served as raw data for estimating genetic similarities among these lines. The patterns of genetic divergence revealed by the SSR polymorphisms were consistent with known pedigrees. A cluster analysis placed the inbred lines in nine clusters that correspond to major heterotic groups or market classes for North American maize. A unique fingerprint for each inbred line could be obtained from as few as five SSR loci. The utility of polymerase chain reaction (PCR)-based markers such as SSRs for measuring genetic diversity, for assigning lines to heterotic groups and for genetic fingerprinting equals or exceeds that of RFLP markers, a property that may prove a valuable asset for a maize breeding program.

Journal ArticleDOI
TL;DR: Results indicate that GLAST plays active roles both in the cerebellar climbing fibre synapse formation and in preventing excitotoxic Cerebellar damage after acute brain injury.
Abstract: To study the function of GLAST, a glutamate transporter highly expressed in the cerebellar Bergmann astrocytes, the mouse GLAST gene was inactivated. GLAST-deficient mice developed normally and could manage simple coordinated tasks, such as staying on a stationary or a slowly rotating rod, but failed more challenging task such as staying on a quickly rotating rod. Electrophysiological examination revealed that Purkinje cells in the mutant mice remained to be multiply innervated by climbing fibres even at the adult stage. We also found that oedema volumes in the mutant mice increased significantly after cerebellar injury. These results indicate that GLAST plays active roles both in the cerebellar climbing fibre synapse formation and in preventing excitotoxic cerebellar damage after acute brain injury.

Journal ArticleDOI
TL;DR: The high strength of binding combined with force-dependent rate constants and high molecular elasticity are tailored to support physiological leukocyte rolling to determine the intrinsic molecular properties of this dynamic adhesion process.
Abstract: Leukocytes roll along the endothelium of postcapillary venules in response to inflammatory signals. Rolling under the hydrodynamic drag forces of blood flow is mediated by the interaction between selectins and their ligands across the leukocyte and endothelial cell surfaces. Here we present force-spectroscopy experiments on single complexes of P-selectin and P-selectin glycoprotein ligand-1 by atomic force microscopy to determine the intrinsic molecular properties of this dynamic adhesion process. By modeling intermolecular and intramolecular forces as well as the adhesion probability in atomic force microscopy experiments we gain information on rupture forces, elasticity, and kinetics of the P-selectin/P-selectin glycoprotein ligand-1 interaction. The complexes are able to withstand forces up to 165 pN and show a chain-like elasticity with a molecular spring constant of 5.3 pN nm−1 and a persistence length of 0.35 nm. The dissociation constant (off-rate) varies over three orders of magnitude from 0.02 s−1 under zero force up to 15 s−1 under external applied forces. Rupture force and lifetime of the complexes are not constant, but directly depend on the applied force per unit time, which is a product of the intrinsic molecular elasticity and the external pulling velocity. The high strength of binding combined with force-dependent rate constants and high molecular elasticity are tailored to support physiological leukocyte rolling.

Journal Article
TL;DR: It is reported that IL-10 inhibits alloantigen-specific proliferative responses and induces a long lasting anergic state in human purified CD8+ T cells when added concomitantly with the Ag in the presence of APC, and the generation of allospecific cytotoxic activity is inhibited byIL-10.
Abstract: IL-10 is a well-documented immunosuppressant that inhibits macrophage-dependent Ag presentation and CD4+ T cell proliferation in vitro. We report that IL-10 inhibits alloantigen-specific proliferative responses and induces a long lasting anergic state in human purified CD8+ T cells when added concomitantly with the Ag in the presence of APC. Moreover, the generation of allospecific cytotoxic activity is inhibited by IL-10. These effects are indirect and are mediated through inhibition of the costimulatory functions of APC. In contrast, IL-10 has no direct inhibitory effects on the proliferation of purified CD8+ T cells activated by anti-CD3 mAb and promotes the growth of activated CD8+ T cells in combination with low doses of IL-2. Taken together, these results indicate that IL-10 has differential effects on CD8+ T cells depending on their state of activation, which may explain both the enhancing and inhibitory effects observed after IL-10 treatment in different in vivo experimental models.

Journal ArticleDOI
J. E. De Vries1
TL;DR: IL-13 is an antiinflammatory cytokine that plays a unique role in the induction and maintenance of IgE production and IgE-mediated allergic responses and has potent antiinflammatory activities in vivo.
Abstract: IL-13 is a cytokine that is produced by different T-cell subsets and dendritic cells. IL-13 shares many biologic activities with IL-4. This is due to the fact that IL-13- and IL-4-receptor complexes share the IL-4-receptor alpha-chain, which is important for signal transduction. T cells do not express functional IL-13 receptors. This is the reason why IL-13, in contrast to IL-4, fails to induce TH2-cell differentiation, one of the hallmarks of the allergic response. However, IL-13 is required for optimal induction of IgE synthesis, particularly in situations in which IL-4 production is low or absent. On the other hand, IL-13 inhibits proinflammatory cytokine and chemokine production in vitro and has potent antiinflammatory activities in vivo. From these observations, it can be concluded that IL-13 is an antiinflammatory cytokine that plays a unique role in the induction and maintenance of IgE production and IgE-mediated allergic responses.

Journal ArticleDOI
TL;DR: The in vivo distribution of albumin carriers in rats was investigated using magnetic resonance imaging (MRI), and no differences in blood circulation times and organ accumulation between different nanoparticle preparations with positive, neutral and negative surface charges could be observed in rats, suggesting that the in vivo fate ofalbumin nanoparticles is significantly influenced by factors not reflected in the in vitro cell culture models.

Patent
16 Jul 1998
TL;DR: In this article, a new crystalline form of the methanesulfonic acid addition salt of 4-(4-methylpiperazin-1-ylmethyl)-N-[4methyl-3-(4pyridin-3-yl)pyrimidine-2-ylamino)phenyl]-benzamide of formula (I), which may be used for example for tumour therapy.
Abstract: The invention relates to a new crystalline form of the methanesulfonic acid addition salt of 4-(4-methylpiperazin-1-ylmethyl)-N-[4-methyl-3-(4-pyridin-3-yl)pyrimidin-2-ylamino)phenyl]-benzamide of formula (I), which may be used for example for tumour therapy.

Journal ArticleDOI
TL;DR: Evaluated by site‐directed mutagenesis the contributions of individual amino acid residues/positions for IgE binding to Bet v 1, the major allergen of birch pollen, and found that IgEbinding toBet v 1 depended on at least six amino acid sequences, but conserved T cell activating capacity is necessary for immunomodulation.
Abstract: Specific immunotherapy is an efficient treatment for patients suffering from type I allergy. The mechanisms underlying successful immunotherapy are assumed to operate at the level of T helper cells, leading to a modulation of the immune response to allergens. During immunotherapy, increasing doses of allergens are given on a regular basis, and the beneficial effects for the patient depend on the concentration of allergen used. On the other hand, the risk of IgE-mediated anaphylactic side effects also increase with the amount of allergen applied per injection. Therefore, we have proposed the use of hypoallergenic (low IgE binding activity) forms of allergens for immunotherapy. We evaluated by site-directed mutagenesis the contributions of individual amino acid residues/positions for IgE binding to Bet v 1, the major allergen of birch pollen. We found that IgE binding to Bet v 1 depended on at least six amino acid residues/positions. Immunoblot analyses and inhibition experiments showed that the multiple-po...

Journal ArticleDOI
TL;DR: Experimental and theoretical studies of the structural properties of chiral peptoids lay the groundwork for the rational design of more complex polypeptoid molecules, with a variety of applications, ranging from nanostructures to nonviral gene delivery systems.
Abstract: Polymers of N-substituted glycines (“peptoids”) containing chiral centers at the α position of their side chains can form stable structures in solution. We studied a prototypical peptoid, consisting of five para-substituted (S)-N-(1-phenylethyl)glycine residues, by NMR spectroscopy. Multiple configurational isomers were observed, but because of extensive signal overlap, only the major isomer containing all cis-amide bonds was examined in detail. The NMR data for this molecule, in conjunction with previous CD spectroscopic results, indicate that the major species in methanol is a right-handed helix with cis-amide bonds. The periodicity of the helix is three residues per turn, with a pitch of ≈6 A. This conformation is similar to that anticipated by computational studies of a chiral peptoid octamer. The helical repeat orients the amide bond chromophores in a manner consistent with the intensity of the CD signal exhibited by this molecule. Many other chiral polypeptoids have similar CD spectra, suggesting that a whole family of peptoids containing chiral side chains is capable of adopting this secondary structure motif. Taken together, our experimental and theoretical studies of the structural properties of chiral peptoids lay the groundwork for the rational design of more complex polypeptoid molecules, with a variety of applications, ranging from nanostructures to nonviral gene delivery systems.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the relationship of motivation to transfer skills and knowledge learned in a computer-based training program with five groups of variables: individual or general attitudes, situational specific attitudes, reactions, learning, and work environment factors.
Abstract: This study examines the relationship of motivation to transfer skills and knowledge learned in a computer-based training programme with five groups of variables: individual or general attitudes, situational specific attitudes, reactions, learning, and work environment factors. Hierarchical regression analysis produced a model which explained 60.5% of the variance in motivation to transfer. Individual attitudes and environmental variables explained most of the variance in motivation. A number of mediated relationships were suggested.

Journal ArticleDOI
Ronald J. Polinsky1
TL;DR: Consistent with rivastigmine's pharmacokinetic and pharmacodynamic profiles, Phase II and III trials have demonstrated that the drug is a well-tolerated and effective treatment for AD.

Journal ArticleDOI
TL;DR: In this article, the distributions of two alternative splicing variants of the metabotropic glutamate receptor mGluR7, mGLuR7a and mGLUR7b, were examined immunohistochemically in the rat and mouse by using variant-specific antibodies raised against C-terminal portions of rat mGsluR 7a and human mGrl7b.
Abstract: The distributions of two alternative splicing variants of metabotropic glutamate receptor mGluR7, mGluR7a and mGluR7b, were examined immunohistochemically in the rat and mouse by using variant-specific antibodies raised against C-terminal portions of rat mGluR7a and human mGluR7b. Many regions throughout the central nervous system (CNS) showed mGluR7-like immunoreactivities (LI). The distribution patterns of mGluR7-LI in the rat were substantially the same as those in the mouse, although some species differences were observed in a few regions. Intense mGluR7a-LI was seen in the main and accessory olfactory bulbs, anterior olfactory nucleus, islands of Calleja, superficial layers of the olfactory tubercle, piriform cortex and entorhinal cortex, periamygdaloid cortex, amygdalohippocampal area, hippocampus, layer I of the neocortical regions, globus pallidus, superficial layers of the superior colliculus, locus coeruleus, and superficial layers of the medullary and spinal dorsal horns. The distribution of mGluR7b was more restricted. It was intense in the islands of Calleja, substantia innominata, hippocampus, ventral pallidum, and globus pallidus. The medial habenular nucleus also showed intense mGluR7a-LI in the rat but not in the mouse. For both mGluR7a- and mGluR7b-LI, localization in the active zones of presynaptic axon terminals was confirmed electron microscopically at synapses of both the asymmetrical and symmetrical types. It is noteworthy that mGluR7a-LI is seen preferentially in relay nuclei of the sensory pathways and that both mGluR7a- and mGluR7b-LI are observed not only in presumed glutamatergic axon terminals, but also in non-glutamatergic axon terminals including presumed inhibitory ones. Thus, mGluR7 may play roles not only as an autoreceptor in glutamatergic axon terminals, but also as a presynaptic heteroreceptor in non-glutamatergic axon terminals in various CNS regions.

Journal ArticleDOI
TL;DR: Letrozole 2.5 mg was superior to AG in time to progression, time to treatment failure and overall survival, and offers longer disease control in the treatment of postmenopausal women with advanced breast cancer, previously treated with anti-oestrogens.

Journal ArticleDOI
TL;DR: CD measurements, indicating a new secondary structure of certain beta-peptides constructed of beta2- and beta3-amino acids, were confirmed by detailed NMR soln.-structure anal, and possible factors influencing the relative stability of the two types of helixes are discussed.
Abstract: Enantiomerically pure beta-amino acid derivs. with the side-chains of Ala, Val, and Leu in the 2- or 3-position (β2- and β3-amino acids, resp.), as well as with substituents in both the 2- and 3-positions (β2,3-amino acids, of like-configuration) were prepd. and incorporated into β-hexa-, β-hepta-, and β-dodecapeptides. The new and some of the previously prepd. beta-peptides showed NH/ND exchange rates (in MeOH at room temp.) with tau1/2 ? 60 days, unrivaled by short-chain alpha-peptides. All beta-peptides were designed to be able to attain the previously described 31-helical structure. CD measurements, indicating a new secondary structure of certain beta-peptides constructed of beta2- and beta3-amino acids, were confirmed by detailed NMR soln.-structure anal. A beta2-heptapeptide and a beta2,3-hexapeptide have the 31-helical structure, while to a beta2/beta3-hexapeptide with alternating substitution pattern H-(beta2-Xaa-beta3-Xaa)3-OH a novel, unusual helical structure (in (D5)pyridine and in CD3OH) was assigned, with a central 10-membered and 2 terminal 12-membered H-bonded rings, and with C:O and N-H bonds pointing alternatively up and down along the axis of the helix. Thus, two types of beta-peptide turns were identified in soln. Hydrophobic interactions of and hindrance to solvent accessibility by the aliph. side-chains are discussed as possible factors influencing the relative stability of the two types of helixes.

Journal ArticleDOI
TL;DR: This strategy of covalent immobilization and measuring well separated single molecules allows the characterization of ligand binding forces in molecular repertoires at the single molecule level and will provide a deeper insight into biorecognition processes.
Abstract: Antibody single-chain Fv fragment (scFv) molecules that are specific for fluorescein have been engineered with a C-terminal cysteine for a directed immobilization on a flat gold surface. Individual scFv molecules can be identified by atomic force microscopy. For selected molecules the antigen binding forces are then determined by using a tip modified with covalently immobilized antigen. An scFv mutant of 12% lower free energy for ligand binding exhibits a statistically significant 20% lower binding force. This strategy of covalent immobilization and measuring well separated single molecules allows the characterization of ligand binding forces in molecular repertoires at the single molecule level and will provide a deeper insight into biorecognition processes.


Journal ArticleDOI
TL;DR: It is found that a 76– amino acid fragment of fibronectin (III1-C) that forms one of the self-assembly sites caused disassembly of preformed fibronsectin matrix without affecting cell adhesion, and that fibronctin matrix is required for Rho activation and cell cycle progression.
Abstract: Adherent cells assemble fibronectin into a fibrillar matrix on their apical surface. The fibril formation is initiated by fibronectin binding to the integrins α5β1 and αvβ3, and is completed by a process that includes fibronectin self-assembly. We found that a 76– amino acid fragment of fibronectin (III1-C) that forms one of the self-assembly sites caused disassembly of preformed fibronectin matrix without affecting cell adhesion. Treating attached fibroblasts or endothelial cells with III1-C inhibited cell migration and proliferation. Rho-dependent stress fiber formation and Rho-dependent focal contact protein phosphorylation were also inhibited, whereas Cdc42 was activated, leading to actin polymerization into filopodia. ACK (activated Cdc42-binding kinase) and p38 MAPK (mitogen-activated protein kinase), two downstream effectors of Cdc42, were activated, whereas PAK (p21-activated kinase) and JNK/SAPK (c-Jun NH2-terminal kinase/ stress-activated protein kinase) were inhibited. III1-C treatment also modulated activation of JNK and ERK (extracellular signal-regulated kinases) in response to growth factors, and reduced the activity of the cyclin E–cdk2 complex. These results indicate that the absence of fibronectin matrix causes activation of Cdc42, and that fibronectin matrix is required for Rho activation and cell cycle progression.

Journal ArticleDOI
TL;DR: The function of each prn gene product is described, which encode proteins identical in size and serology to proteins present in wild-type Pseudomonas fluorescens, but absent from a mutant from which the entirePrn gene region had been deleted.
Abstract: Pyrrolnitrin is a secondary metabolite derived from tryptophan and has strong antifungal activity. Recently we described four genes, prnABCD, from Pseudomonas fluorescens that encode the biosynthesis of pyrrolnitrin. In the work presented here, we describe the function of each prn gene product. The four genes encode proteins identical in size and serology to proteins present in wild-type Pseudomonas fluorescens, but absent from a mutant from which the entire prn gene region had been deleted. The prnA gene product catalyzes the chlorination of l-tryptophan to form 7-chloro-l-tryptophan. The prnB gene product catalyzes a ring rearrangement and decarboxylation to convert 7-chloro-l-tryptophan to monodechloroaminopyrrolnitrin. The prnC gene product chlorinates monodechloroaminopyrrolnitrin at the 3 position to form aminopyrrolnitrin. The prnD gene product catalyzes the oxidation of the amino group of aminopyrrolnitrin to a nitro group to form pyrrolnitrin. The organization of the prn genes in the operon is identical to the order of the reactions in the biosynthetic pathway.

Patent
11 Feb 1998
TL;DR: In this article, the authors introduced the notion of a bridge in sub-formula (I*) where one or two of the ring members T1, T2, T3, and T4 are nitrogen, and the remainder are in each case CH.
Abstract: The invention relates to compounds of formula (I), wherein r is 0 to 2, n is 0 to 2; m is 0 to 4; R1 and R2 (i) are in each case a lower alkyl, or (ii) together form a bridge in subformula (I*) or (iii) together form a bridge in subformula (I**), wherein one or two of the ring members T1, T2, T3, and T4 are nitrogen, and the remainder are in each case CH; A, B, D, and E are N or CH, wherein not more than 2 of these radicals are N; G is lower alkylene, acyloxy- or hydroxy-lower alkylene, -CH2-O-, -CH2-S-, -CH2-NH-, oxa, thia, or imino; Q is methyl; R is H or lower alkyl; X is imino, oxa, or thia; Y is aryl, pyridyl, or (un)substituted cycloalkyl; and Z is mono- or disubstituted amino, halogen, alkyl, substituted alkyl, hydroxy, etherified or esterified hydroxy, nitro, cyano, carboxy, esterified carboxy, alkanoyl, carbamoyl, N-mono- or N,N-disubstituted carbamoyl, amidino, guanidino, mercapto, sulfo, phenylthio, phenyl-lower alkylthio, alkylphenylthio, phenylsulfinyl, phenyl-lower alkylsulfinyl, alkylphenylsulfinyl, phenylsulfonyl, phenyl-lower alkylsulfonyl, or alkylphenylsulfonyl; and wherein the bonds characterized by a wavy line are either single or double bonds; or an N-oxide of said compound with the stipulation that, if Y is pyridyl or unsubstituted cycloalkyl, X is imino, and the remaining radicals are as defined, then G is selected from the group comprising lower alkylene, -CH2-O-, -CH2-S-, oxa and thia; or a salt thereof. The compounds inhibit angiogenesis.