High Tendency (high + tendency)

Distribution by Scientific Domains

Selected Abstracts

Fine-needle aspiration of dedifferentiated acinic cell carcinoma: Report of a case with cyto-histological correlation

Sharlin Johnykutty M.D.
Abstract Dedifferentiated Acinic Cell Carcinoma (DAcCC) is a rare salivary gland malignancy. It has a high tendency to recur and metastasize and thus has a poor prognosis. So far, to our knowledge, only one case of DAcCC has been reported in the cytology literature. Herein, we describe a second case of DAcCC from a fine-needle aspiration (FNA) along with its subsequent histological correlation. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source]

Synthesis and Crystal Structure of a Heptanuclear and an Octanuclear Copper(II) Complex Derived from ,- D -Glucofuranoses

Michael Gottschaldt
Abstract CuII complexes of different 6-(,-keto-enamino)-6-deoxy-1,2- O -isopropylidene-,- D -glucofuranoses 3a,f have a high tendency to build up oligonuclear clusters. Two new oligonuclear copper(II) complexes could be synthesised, crystallised and their structures determined. The complex Cu(3a) was found to consist of a heptanuclear cluster in which two ,-cubane like substructures share one copper ion. The structure is highly asymmetric and in the cluster every CuII ion has a different coordination geometry. Variation of the residues of the ,-ketoenaminic unit leads to the formation of the octanuclear copper(II) complex Cu(3e). Similarly, this has two ,-cubane subunits consisting of a heptanuclear structure with an additionally attached copper ion. In the crystal, two Cu8 cluster molecules are found differing in their geometries due to intermolecular interactions responsible for the formation of a supramolecular network. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Self-Assembly of a Donor-Acceptor Dyad Across Multiple Length Scales: Functional Architectures for Organic Electronics

Jeffrey M. Mativetsky
Abstract Molecular dyads based on polycyclic electron donor (D) and electron acceptor (A) units represent suitable building blocks for forming highly ordered, solution-processable, nanosegregated D-A domains for potential use in (opto)electronic applications. A new dyad, based on alkyl substituted hexa- peri -hexabenzocoronene (HBC) and perylene monoimide (PMI) separated by an ethinylene linker, is shown to have a high tendency to self-assemble into ordered supramolecular arrangements at multiple length scales: macroscopic extruded filaments display long-range crystalline order, nanofiber networks are produced by simple spin-coating, and monolayers with a lamellar packing are formed by physisorption at the solution-HOPG interface. Moreover, highly uniform mesoscopic ribbons bearing atomically flat facets and steps with single-molecule heights self-assemble upon solvent-vapor annealing. Electrical measurements of HBC-PMI films and mesoscopic ribbons in a transistor configuration exhibit ambipolar transport with well balanced p- and n-type mobilities. Owing to the increased level of order at the supramolecular level, devices based on ribbons show mobility increases of more than one order of magnitude. [source]

Nonstructural 3/4A protease of hepatitis C virus activates epithelial growth factor,induced signal transduction by cleavage of the T-cell protein tyrosine phosphatase,

HEPATOLOGY, Issue 6 2009
Erwin Daniel Brenndörfer
The hepatitis C virus (HCV) is a worldwide major cause of chronic liver disease with a high tendency to establish a persistent infection. To permit persistent replication of viral genomes through the cellular translation machinery without affecting host cell viability, viruses must have developed mechanisms to control cellular cascades required for sufficient viral replication, on the one hand, and to adapt viral replication to the cellular requirements on the other hand. The present study aimed to further elucidate mechanisms by which HCV targets growth factor signaling of the host cell and their implications for viral replication. The study describes a novel mechanism by which HCV influences the activation of the epithelial growth factor receptor/Akt pathway through a nonstructural (NS)3/4A-dependent down-regulation of the ubiquitously expressed tyrosine phosphatase T cell protein tyrosine phosphatase (TC-PTP). NS3/4A is demonstrated to cleave TC-PTP protease-dependently in vitro at two cleavage sites. The in vivo relevance of this finding is supported by the fact that down-regulation of TC-PTP protein expression could also be demonstrated in HCV-infected individuals and in transgenic mice with intrahepatic expression of NS3/4A. Conclusion: This down-regulation of TC-PTP results in an enhancement of epithelial growth factor (EGF)-induced signal transduction and increases basal activity of Akt, which is demonstrated to be essential for the maintenance of sufficient viral replication. Hence, therapeutic targeting of NS3/4A may not only disturb viral replication by blocking the processing of the viral polyprotein but also exerts unforeseen indirect antiviral effects, further diminishing viral replication. (HEPATOLOGY 2009;49:1810,1820.) [source]

Conformation-dependent side reactions in interstrand-disulfide bridging of trimeric collagenous peptides by regioselective cysteine chemistry

Barbara Saccá
Abstract Conversion of single-chain or disulfide-bridged dimeric collagenous peptides into Cys(Npys) derivatives as activated species for subsequent regioselective thiol/disulfide exchange reactions leads to side products whose origin and nature was determined by HPLC and ESI-MS. In both cases the high tendency of the educts to self-associate into triple-helical homotrimers, as assessed by their dichroic properties in the reaction media, is responsible for the failure of this well established cysteine chemistry. Only by optimizing the synthetic strategy or by exploiting a kinetic control of the reaction, could these conformation-dependent limitations be more or less efficiently bypassed for the regioselective assembly of heterotrimeric collagen model peptides crosslinked with artificial cystine knots. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source]

Design, synthesis, characterization and in-vivo activity of a novel salmon calcitonin conjugate containing a novel PEG-lipid moiety

Weiqiang Cheng
Abstract Objectives The aim of the study was to explore (1) the synthesis of a novel poly(ethylene glycol) modified lipid (PEG-lipid, PL) containing a chemically active tri-block linker, ,-maleimido lysine (Mal), and its conjugation with salmon calcitonin (sCT), and (2) the biophysical properties and activity of the resulting conjugate, Mal-PL-sCT, relative to the control, 2PEG-Mal-sCT, which comprises sCT conjugated with ,-palmitoyl- N -,-maleimido- l -lysine at cysteine 1 and cysteine 7, and PEG moieties at lysine 11 and lysine 18 via a conventional stepwise method. Methods The PEG-lipid was obtained by condensing palmitic acid derivative of ,-maleimido lysine with methoxy poly(ethylene glycol) amine. Under reductive conditions, the PEG-lipid readily reacted with sCT to yield the resultant compound, Mal-PL-sCT. Key findings Dynamic light scattering analyses suggested that Mal-PL-sCT and 2PEG-Mal-sCT exhibited robust helical structures with a high tendency to aggregate in water. Both compounds were more stable against intestinal degradation than sCT, although Mal-PL-sCT was less stable than 2PEG-Mal-sCT. However, 2PEG-Mal-sCT did not possess hypocalcaemic activity while Mal-PL-sCT retained the hypocalcaemic activity of sCT when it was subcutaneously injected in the rat model. Multiple functional groups may be conjugated to a peptide via a tri-block linker without the risk of obliterating the intrinsic bioactivity of the peptide. Conclusions The resultant novel PEG-lipid has a potential role to optimize protein and peptide delivery. [source]

Preparation and Characterisation of Pd Nanoclusters in Hyperbranched Aramid Templates to be used in Homogeneous Catalysis

Daniela Tabuani
Abstract In the present paper the potential use of hyperbranched (HB) aramids as metallic solution stabilisers and carriers for homogeneous catalysis is outlined. Aramids, synthesised either from A2,+,B3 reagents [namely, p -phenylenediamine (PPD) and trimesic acid (TMA)] or from an AB2 monomer [i.e., 5-(4-aminobenzamido)isophtalic acid, named ABZAIA], have been used to stabilise palladium nanoclusters dispersed in two solvent media, namely N,N, -dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The influence of the nature of the polymeric support as well as of the solvent medium on both cluster dimensions and stability of the solutions has been investigated. Indeed, the interactions between the polymeric support and the metallic precursor (PdCl2), as revealed by 1H NMR spectroscopy, involve only the amino groups of the HB aramids. Metal nanocluster dimensions and stability are strongly dependent on the polymer used as a stabilizer. Transmission electron microscopy (TEM) analysis has shown that the presence of HB polymer in the solution reduces cluster dimensions and allows the obtaining of stable systems. The low concentration of NH2 end groups in the poly(AB2) system leads to the formation of Pd particles of rather low dimensions with a high tendency to aggregate. All prepared solutions are stable under inert atmosphere for at least a month, with an improved stabilisation when using the poly(A2,+,B3) system for more than five months. A TEM micrograph of poly(ABZAIA)/Pd from a DMSO solution. [source]

Ketotic hypoglycemia in patients with allergic diseases

Tomoyo Matsubara
AbstractBackground:,Ketotic hypoglycemia is the most common cause of recurrent hypoglycemia in early childhood but its etiology is poorly understood. Elimination diets have been used for the prevention or treatment of some allergic diseases; however, these diets entail a risk to the normal nutrition and growth of children. The present study investigated whether elimination diets are related to the occurrence of ketotic hypoglycemia. Methods:,The prevalence of allergy treated with elimination diet therapy was retrospectively investigated in 18 patients with ketotic hypoglycemia seen in Yamaguchi University Hospital between January 1995 and September 1999. Data were gathered by reviewing the patients' medical charts. Results:,Ten (55.6%) of 18 patients with ketotic hypoglycemia had allergic diseases. Six (60%) of the patients had been treated with strict elimination diets and the others were on incomplete elimination diets for the prevention of allergy. The ketotic hypoglycemia patients with allergic diseases had experienced fewer pre-existing infectious diseases than those without allergic diseases. Conclusions:,Patients with allergic diseases treated with elimination diets have a relatively high tendency towards developing ketotic hypoglycemia. They might have a lower capacity to tolerate fasting due to their excessive avoidance of many foods, even during periods when they are not undergoing strict elimination diets. [source]