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Heterozygous mutations in proline-rich transmembrane protein 2 (PRRT2) underlie a group of paroxysmal disorders, including epilepsy, kinesigenic dyskinesia, and migraine. Most of the mutations lead to impaired PRRT2 expression, suggesting that loss of PRRT2 function may contribute to pathogenesis. We show that PRRT2 is enriched in presynaptic terminals and that its silencing decreases the number of synapses and increases the number of docked synaptic vesicles at rest. PRRT2-silenced neurons exhibit a severe impairment of synchronous release, attributable to a sharp decrease in release probability and Ca2+sensitivity and associated with a marked increase of the asynchronous/synchronous release ratio. PRRT2 interacts with the synaptic proteins SNAP-25 and synaptotagmin 1/2. The results indicate that PRRT2 is intimately connected with the Ca2+-sensing machinery and that it plays an important role in the final steps of neurotransmitter release.

An innovative approach in the field of nanomaterials is to develop modern and mild synthetic protocols that enable controlled and integrated organization of specific functional organic and biological building blocks. In this context, research on the preparation of clay-based organic-inorganic hybrid materials, i.e. organoclays, has received considerable attention because these lamellar materials not only possess highly ordered structure in 2D, but also provide interesting chemical intercalation and surface properties. As a result entrapment and orientation of various functional guest molecules into layered inorganic solids, has been well exploited. At present there is a great deal of interest in the rational design of hybrid organic-/bio-inorganic composites on the nanometer to micrometer length scales. These hybrids encompass highly selective recognition properties associated with organic and biological species, combined with catalytic, optical, and electronic properties of the inorganic lamellar framework. This paper presents an overview of microwave application in different preparation steps of organophilic clays, their modification and their addition to polymeric matrices. Particular attention has been given to the microwave-mediated hydrothermal technique, as innovative and eco-friendly protocol for the intercalation of different kinds of organic hosts into the interlayer of clay minerals. The few pioneering complete microwave-mediated preparation procedures, exploiting advantages of dielectric heating in both the synthesis of the organic host molecule and the intercalation in the clay structure, have been also highlighted.

Microwaves (MW) at the ISM frequency of 2.45 GHz have been used to ignite the Combustion Synthesis (CS) of pressed ceramic and metallic powders mixtures, using a single-mode applicator (TE103). This experimental apparatus allows to study the separate effect of prevalent electric or magnetic field on the selective heating of the reactive powders compacts, while transferring energy and not heat before and after CS. Microwave activated combustion syntheses (MACS) of TiC-40 wt%Fe and FeAl intermetallic compounds were performed in the two different field configurations (maximum of the electric field (E) and maximum of magnetic field (H)) in order to investigate any possible difference in the reaction mechanism and in the final microstructure of the products. MACS in the maximum of E has also been applied to high temperature materials joining, with the application of a moderate pressure during the irradiation with electromagnetic waves, to promote adhesion and to reduce the newly formed compounds porosity.

In this work attempts to prepare strontium-doped lanthanum manganites La1-xSrxMnO3 using microwave-assisted hydrothermal synthesis were undertaken from a mixture of lanthanum nitrate, strontium nitrate, manganese(II) nitrate, potassium permanganate and potassium hydroxide as a mineralizer. For x = 0.3, and x = 0.5, the perovskite obtained is not defined since both La0.7Sr0.3MnO3 and La0.5Sr0.5MnO3 phases are consistent with XRD spectra. While with x = 1.0, for the first time, hexagonal strontium manganite was prepared as blade-shaped crystallites with a narrow particle length distribution (range 3.75-7.75 μm) at 210°C using a treatment time of only 1 hour. Conventional hydrothermal synthetic routes require at least 24 hrs treatment time.

Microwaves (MW) at the ISM frequency of 2.45 GHz have been used to ignite the Combustion Synthesis (CS) of pressed ceramic and metallic powders mixtures, using a single-mode applicator (TE103). This experimental apparatus allows to study the separate effect of prevalent electric or magnetic field on the selective heating of the reactive powders compacts, while transferring energy and not heat before and after CS. Microwave activated combustion syntheses (MACS) of TiC-40 wt%Fe and FeAl intermetallic compounds were performed in the two different field configurations (maximum of the electric field (E) and maximum of magnetic field (H)) in order to investigate any possible difference in the reaction mechanism and in the final microstructure of the products. MACS in the maximum of E has also been applied to high temperature materials joining, with the application of a moderate pressure during the irradiation with electromagnetic waves, to promote adhesion and to reduce the newly formed compounds porosity.

Scanning electron microscopy characterization of the materials obtained by homogeneous and heterogeneous catalytic polymerization of phenylacetylene is described. The catalysts used are β‐dioxygenato rhodium(I) complexes. The effects of the reaction medium, presence of a cocatalyst and the type of catalysis (homogeneous or heterogeneous) on the morphology of the polymers obtained have been studied and discussed. Using a supported complex at 0 °C, nanoparticles with a diameter distribution as narrow as 30 to 70 nm were obtained. Polymer nanopowders were found to be unaffected by ageing. Copyright © 2003 John Wiley & Sons, Ltd.

Scanning electron microscopy characterization of the materials obtained by homogeneous and heterogeneous catalytic polymerization of phenylacetylene is described. The catalysts used are β-dioxygenato rhodium(I) complexes. The effects of the reaction medium, presence of a cocatalyst and the type of catalysis (homogeneous or heterogeneous) on the morphology of the polymers obtained have been studied and discussed. Using a supported complex at 0 °C, nanoparticles with a diameter distribution as narrow as 30 to 70 nm were obtained. Polymer nanopowders were found to be unaffected by ageing. Copyright © 2003 John Wiley & Sons, Ltd.

Olf/Ebf transcription factors have been implicated in numerous developmental processes, ranging from B-cell development to neuronal differentiation. We describe mice that carry a targeted deletion within theEbf2 (O/E3) gene. In Ebf2-null mutants, because of defective migration of gonadotropin releasing hormone-synthesizing neurons, formation of the neuroendocrine axis (which is essential for pubertal development) is impaired, leading to secondary hypogonadism. In addition,Ebf2-/- peripheral nerves feature defective axon sorting,hypomyelination, segmental dysmyelination and axonal damage, accompanied by a sharp decrease in motor nerve conduction velocity. Ebf2-null mice reveal a novel genetic cause of hypogonadotropic hypogonadism and peripheral neuropathy in the mouse, disclosing an important role for Ebf2 in neuronal migration and nerve development.

The condensation reaction of thiobenzamide, (as well as thionicotinamide and isothionicotinamide) in the presence of dimethyl sulfoxide and of an acid, affords 3,5‐diphenyl‐1,2,4‐thiadiazole. Under the same experimental conditions, N‐substituted thioureas are also condensed to 1,2,4‐thiadiazole derivatives; their structure is ascertained by spectroscopic properties and by X‐ray diffraction. Some information on the mechanism of thiadiazoles formation from both starting classes of compounds, thiobenzamides and N‐substituted thiourea, is collected and discussed.

Loss-of-function mutations in proline-rich transmembrane protein-2 (PRRT2) cause paroxysmal disorders associated with defective Ca2+dependence of glutamatergic transmission. We find that either acute or constitutive PRRT2 deletion induces a significant decrease in the amplitude of evoked excitatory postsynaptic currents (eEPSCs) that is insensitive to extracellular Ca2+and associated with a reduced contribution of P/Q-type Ca2+channels to the EPSC amplitude. This synaptic phenotype parallels a decrease in somatic P/Q-type Ca2+currents due to a decreased membrane targeting of the channel with unchanged total expression levels. Co-immunoprecipitation, pull-down assays, and proteomics reveal a specific and direct interaction of PRRT2 with P/Q-type Ca2+channels. At presynaptic terminals lacking PRRT2, P/Q-type Ca2+channels reduce their clustering at the active zone, with a corresponding decrease in the P/Q-dependent presynaptic Ca2+signal. The data highlight the central role of PRRT2 in ensuring the physiological Ca2+sensitivity of the release machinery at glutamatergic synapses.

Motivation: Polymerase chain reaction (PCR)‐based RNA fingerprinting is a powerful tool for the isolation of differentially expressed genes in studies of neoplasia, differentiation or development. Arbitrarily primed RNA fingerprinting is capable of targeting coding regions of genes, as opposed to differential display techniques, which target 3′ non‐coding cDNA. In order to be of general use and to permit a systematic survey of differential gene expression, RNA fingerprinting has to be standardized and a number of highly efficient and selective arbitrary primers must be identified.Results: We have applied a rational approach to generate a representative panel of high‐efficiency oligonucleotides for RNA fingerprinting studies, which display marked affinity for coding portions of known genes and, as shown by preliminary results, of novel ones. The choice of oligonucleotides was driven by computer simulations of RNA fingerprinting reverse transcriptase (RT)‐PCR experiments, performed on two custom‐generated, non‐redundant nucleotide databases, each containing the complete collection of deposited human or murine cDNAs. The simulation approach and experimental protocol proposed here permit the efficient isolation of coding cDNA fragments from differentially expressed genes.Availability: Freely available on request from the authors.Contact: fesce.riccardo@hsr.it

Thiobenzamide and thionicotnamide S-oxide were prepared as intermediates in the dimerization of corresponding thioamides to 1,2,4-thiadiazoles and the X-ray crystal structure of thionicotinamide S-oxide water solvate was determined. Crystals belong to orthorhombic Pbcaspace group with a= 14.129(3), b= 7.299(2), c= 15.277(3)Å, and Z = 8. The geometry of the molecule accords well with that found in similar compounds; an intramolecular N–H···O hydrogen bond is present, while the packing is mainly determined by the hydrogen bond system involving the water molecule and the side-chain of the organic molecule. The contacts between pyridine moieties, stacked along the [010] axis, complete the packing.

Basic principles of fabricating tile glazes based on cordieritic glass‐ceramics are explained. Glass compositions from the MgO‐Al2O3‐SiO2three‐component phase diagram have been melted with and without the nucleating agent TiO2. Additionally, a sodium borosilicate glass that is commonly used in the tile glaze industry has been wet milled, together with the previous compositions, to produce a coating slip. Studies are focused on the role of the nucleating agent and glassy formulation in the crystallization of the glass‐ceramic system using differential thermal analysis, X‐ray diffractometry, and scanning electron microscopy. When added to a borosilicate glass, only one composition is capable of crystallizing cordierite under a fast‐firing cycle used for “monoporosa” production. The porosity of the glaze layer is sufficiently low and the crystal size is small to ensure good mechanical and chemical properties. The presence of cordierite crystals in the glaze should enhance abrasion and acid resistance, in comparison to a traditional matte glaze that contains mostly enstatite or diopside crystals.

A series of complexes of di-2-pyridylketone semicarbazone (Hdips) and Mn(II), Co(II), Co(III), Ni(II) and Cu(II) nitrates were synthesized and characterized by means of IR spectroscopy and for cobalt and nickel by X-ray crystal structures. The results are in agreement with the formulae: Mn(Hdips)2(NO3)2·2H2O, [Co(Hdips)2](NO3)2·H2O (I), [Ni(Hdips)2](NO3)2·H2O (II), Cu(Hdips)(NO3)2·2H2O, [Co(dips)2](NO3)·2H2O (III). The structure of I and II are monoclinic, space groupP21/c, with, I,a=15.980(4),b=11.531(2),c=16.170(2)Å;ß=104.20(2)°,Z=4,R=0.032; II,a=16.109(5),b=11.480(3),c=16.135(6)Å;ß=104.15(2)°,Z=4,R=0.069. Compound III is also monoclinic, space groupP21/c witha=12.173(5),b=15.619(5),c=15.338(8)Å;ß=111.40(4)°,Z=4,R=0.059. In these complexes the ligand is tridentate via carbonylic oxygen, semicarbazone and pyridine nitrogens forming each two five membered chelate rings with the metal in a distorted octahedral geometry.

Crystallographic properties of the title compounds are reported and inter- and intra-molecular interactions of the amino group are discussed and related to spectroscopic data. The geometry of the nitrogroups and of the 2-aminoheterocyclic moiety indicate that classical conjugation theory cannot explain the UV/vis spectra. The red shift observed on substituting H by a Me on the 2-amino group is interpreted in terms of internal charge-transfer.

An aluminosilicate glass of composition 61SiO26Al2O310MgO6ZnO·12Li2O·5TiO2(mol%) has been prepared by a melting process and investigated as far as crystallization is concerned. Glass‐ceramic is easily obtained because glass shows a high tendency to crystallize starting from 700°C. The crystalline phases evolve with temperature, showing the aluminosilicates to be the main phase up to 1050°C, followed by metasilicates and silicates, some of which have lower melting points. The titanates of Mg and Zn develop from the phase‐separated glass, soon after Tg, and grow to form nucleation centers for the other crystalline phases. The evolution from phase‐separated glass to glass‐ceramic has been followed by many thermal, diffractometric, spectroscopic, and microscopic techniques.

The synthesis, magnetic, and structural properties of the title compound are reported. The crystals are triclinic, space groupP¯1, witha=15.084(2),b=11.820(1),c=7.5253(7) Å, a=71.50(1),ß=77.61(1), ?=68.68(1)° andZ=1; the structure was solved by Patterson and Fourier methods and refined toR 0.0351 for 4147 observed reflections. The content of the unit cell consists of a centrosymmetrical copper acetate-like molecule in which each copper can be described as square-pyramidally surrounded by four carboxylic oxygens in the basal plane [1.955(2)–1.970(2) Å], one methanolic oxygen in the apical site [2.206(2) Å] and a Cu?Cu interaction of 2.612(5) Å at a sixth position of a distorted octahedron. The dimers are packed by means of hydrogen bonds formed between the methanolic OH group and the carboxylic O(2) atom of one adjacent complex and by normal Van der Waals contacts. The subnormal magnetic moment, characteristic of exchange interactions between the two copper(II) ions, and the energy of the d-d band observed are consistent with the reported dinuclear copper(II) acetate-like structure.

The crystal and molecular structure of the [N(2-ammoniumethyl)piperazinium]tetra-chloromonobromocuprate(II) monohydrate is reported. The crystals are monoclinic, space groupP21/c,Z=4, witha=9.560(2),b=9.240(3),c=18.270(7)Å,ß=99.20(2)°. The structure consists of discrete N(2-ammoniumethyl)piperazinium cations, uncoordinated water molecules and [CuCl4Br]3- anions, in which four coplanar chlorine atoms occupy the square-basal plane and one bromine atom the axial position, giving the copper(II) ion a moderately elongated square-pyramidal geometry. The structure was refined to a finalR index of 0.0765.

Copper(I) complexes, obtained by reacting CuX2 (X = Cl, Br) with 5.5-dimethylimidazolidine-2-thione-4-one (sox), and its 2-one-4-thione (oxs) and 2,4-dithione (ss) derivatives, are reported. Infrared spectra show evidence for S-coordination in all the complexes. The crystal structure of Cu(oxs)2Br shows dimeric units, where every copper(I), practically trigonal planar, undergoes a tetrahedral distorsion by long range interactions with one bridging bromine and one bridging sulphur atom of oxs. The crystal structure of Cu(ss)2Cl is formed by a polymeric chain in which every copper has a tetrahedral environment, achieved by two ligands bridged via the two sulphur atoms between two coppers, one ligand bonded only through the 2-thione sulphur, and one chlorine. The distortions of the C=O and C=S groups from the symmetrical positions with respect to the other two bonds of the C(sp2) carbons, verified in the complexes and in the free ligands, are interpreted in terms of the VSEPR model.

Keratinocytes produce interleukin-1α (IL-1α) and the epithelial variant of its inhibitor, interleukin-1 receptor antagonist (icIL-1ra). Both IL-1α and icIL-1ra lack a secretory signal peptide; however, some icIL-1ra is found in the supernatants of cultured keratinocytes. The lack of correlation with the release of the cytosolic enzyme lactate dehydrogenase suggests that icIL-1ra can be actively secreted. Brefeldin A fails to block icIL-1ra release, suggesting that this protein may be externalized by keratinocytes through a leaderless pathway of secretion. Only minute amounts of soluble extracellular IL-1α are detected: however, both IL-1α and icIL-1ra can be released from the external face of the keratinocyte plasma membrane by mild acidic treatment, suggesting that IL-1α can also be secreted by keratinocytes. The observation of membrane-associated IL-1α and icIL-1ra might reflect an autocrine loop of regulation. Support for this hypothesis comes from the finding that keratinocytes, when exposed to exogenous recombinant IL-1α, increase their content in both IL-1α and IL-1ra mRNA. When keratinocytes are subjected to counterflow centrifugal elutriation, three major cell populations are obtained, representing three different degrees of keratinocyte differentiation. Cells from all populations synthesize IL-1α and IL-1ra: however, while IL-1α is uniformly distributed in cells from all maturational stages, IL-1ra accumulates in large, more differentiated keratinocytes. Changes in the ratio of IL-1ra to IL-1α production and secretion by keratinocytes at different degrees of maturation might contribute to the control of growth and differentiation of human skin.

The crystal structures of inclusion compounds of 4-aminobenzenesulfamidine (sulfaguanidine) (L) with two dicyclohexano-18-crown-6 (DCH-6) isomers A(cis-syn-cis) and B(cis-anti-cis) have been determined by X-ray methods. The complexes exhibit 1:2 host-guest ratios. In fact the complex of isomer A is formulated as [DCH-6A·[L]H2O]L (complexI), while that of isomerB is DCH-6BL2 (complex I1).

Several genetic factors have been proven to contribute to the specification of the metencephalic-mesencephalic territory, a process that sets the developmental foundation for prospective morphogenesis of the cerebellum and mesencephalon. However, evidence stemming from genetic and developmental studies performed in man and various model organisms suggests the contribution of many additional factors in determining the fine subdivision and differentiation of these central nervous system regions. In man, the cerebellar ataxias/aplasias represent a large and heterogeneous family of genetic disorders.

The formation mechanism of praseodymium‐doped zircon stain was studied, using environment scanning electron microscopy (ESEM) primarily. The significance of ESEM as a processing tool for studying chemical and morphologic dynamic changes under controlled temperature conditions was evaluated, with respect to the traditional investigation methods.

Summary New complexes of copper(I) withN,N'-dialkylsubstituted imidazolidine-2-thione ligands were prepared by reduction of CuX2 (X = Cl or Br). The i.r. spectra show that in all the complexes the ligand coordinates through the sulphur atom. The crystal structure of chloro-bis(N,N'-dimethylimidazolidine-2-thione)copper(I) has been determined from x-ray diffraction data. Crystals are monoclinic. space groupC2, with unit cell dimensions:a = 16.022(15),b = 9.942(10),c = 15.112(15) A, ß = 139.84(10)2, Z = 4. The final R index is 5.2%. The copper coordination is trigonal, involving sulphur atoms of the two ligands and One chlorine atom. The steric effect of the two methyls imposes a rotation of the imidazolidine rings with respect to the coordination plane. The dihedral angle between the mean plane of thiourea moieties. parallel one with the other. and the coordination plane is 119.3°.

The crystal structure of the title compound has been determined from x-ray diffractometer data by the heavy-atom method and refined anisotropically by least-squares calculations. Crystals are monoclinic, space groupP 21/c, with unit cell dimensions:a=7.321(1),b=14.622(2),c=14.827(2) Å,ß=92.95(2)°, Z=4. The finalR index is 4.6%. The copper coordination is trigonal, involving the sulphur atoms of twoN-ethyl-1,3-imidazolidine-2-thione molecules and one chlorine atom. The structure is held together by two intramolecular N-H?Cl hydrogen bonds and by normal van der Waals interactions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.