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Common Precursor (common + precursor)
Selected AbstractsChemInform Abstract: Facile Synthesis of Substituted 5-Amino- and 3-Amino-1,2,4-thiadiazoles from a Common Precursor.CHEMINFORM, Issue 20 2010Paul M. Wehn Abstract 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. [source] ChemInform Abstract: Complementary Reactions of Allylic Carbamates Using Palladium(II): Formation of Oxazolidinones or Allylic Amides from a Common Precursor.CHEMINFORM, Issue 18 2009Steven D. R. Christie Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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. [source] ChemInform Abstract: Tandem RCM,Isomerization Approach to Glycals of Desoxyheptoses from a Common Precursor.CHEMINFORM, Issue 23 2008Bernd Schmidt Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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. [source] Characterization of a eukaryotic type serine/threonine protein kinase and protein phosphatase of Streptococcus pneumoniae and identification of kinase substratesFEBS JOURNAL, Issue 5 2005Linda Nováková Searching the genome sequence of Streptococcus pneumoniae revealed the presence of a single Ser/Thr protein kinase gene stkP linked to protein phosphatase phpP. Biochemical studies performed with recombinant StkP suggest that this protein is a functional eukaryotic-type Ser/Thr protein kinase. In vitro kinase assays and Western blots of S. pneumoniae subcellular fractions revealed that StkP is a membrane protein. PhpP is a soluble protein with manganese-dependent phosphatase activity in vitro against a synthetic substrate RRA(pT)VA. Mutations in the invariant aspartate residues implicated in the metal binding completely abolished PhpP activity. Autophosphorylated form of StkP was shown to be a substrate for PhpP. These results suggest that StkP and PhpP could operate as a functional pair in vivo. Analysis of phosphoproteome maps of both wild-type and stkP null mutant strains labeled in vivo and subsequent phosphoprotein identification by peptide mass fingerprinting revealed two possible substrates for StkP. The evidence is presented that StkP can phosphorylate in vitro phosphoglucosamine mutase GlmM which catalyzes the first step in the biosynthetic pathway leading to the formation of UDP- N -acetylglucosamine, an essential common precursor to cell envelope components. [source] An infiltrative variant of non-neural granular cell tumor: a case reportJOURNAL OF CUTANEOUS PATHOLOGY, Issue 2009Iwei Yeh Dermal non-neural granular cell tumors are rare tumors of indeterminate lineage that typically present as well-circumscribed tumors with nuclear pleomorphism and mitotic activity. We describe a dermal non-neural granular cell tumor with a distinctive growth pattern with granular cells interspersed between collagen bundles. This asymptomatic papule arose on the scapula of a 46-year-old woman and consisted of a mixture of epithelioid and spindled granular cells. The immunohistochemical characteristics were similar to those of previously reported dermal non-neural granular cell tumors. Despite mild nuclear pleomorphism and dispersion of lesional cells among collagen bundles, mitoses were not present and Ki-67 staining indicated a low proliferative rate. In addition to being S-100 protein negative and NKI/C3 positive, our case was positive for PGP9.5 and weakly positive for neuron-specific enolase, a staining pattern similar to what has been observed for cellular neurothekeomas. Our case could represent a dermal non-neural granular cell tumor with unique architecture, a granular cellular neurothekeoma or a granular cell dermatofibroma. As both dermal non-neural granular cell tumor and cellular neurothekeoma are of indeterminate lineage, our case with features characteristic of both entities may suggest a common precursor or lineage for dermal non-neural granular cell tumor and cellular neurothekeoma. [source] The Ghrelin/Obestatin Balance in the Physiological and Pathological Control of Growth Hormone Secretion, Body Composition and Food IntakeJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2010R. Hassouna Ghrelin and obestatin are two gastrointestinal peptides obtained by post-translational processing of a common precursor, preproghrelin. Ghrelin is an orexigenic and adipogenic peptide and a potent growth hormone secretagogue (GHS) modified by the enzyme ghrelin- O -acyl-transferase to bind and activate its receptor, the GHS-R. The ghrelin/GHS-R pathway is complex and the effects of ghrelin on GH secretion, adiposity and food intake appear to be relayed by distinct mechanisms involving different transduction signals and constitutive activity for the GH-R, different cofactors as modulators of endogenous ghrelin signalling and/or alternative ghrelin receptors. The discovery of obestatin in 2005 brought an additional level of complexity to this fascinating system. Obestatin was initially identified as an anorexigenic peptide and as the cognate ligand for GPR39, but its effect on food intake and its ability to activate GPR39 are still controversial. Although several teams failed to reproduce the anorexigenic actions of obestatin, this peptide has been shown to antagonise GH secretion and food intake induced by ghrelin and could be an interesting pharmacological tool to counteract the actions of ghrelin. Ghrelin and obestatin immunoreactivities are recovered in the blood with an ultradian pulsatility and their concentrations in plasma vary with the nutritional status of the body. It is still a matter of debate whether both hormones are regulated by independent mechanisms and whether obestatin is a physiologically relevant peptide. Nevertheless, a significant number of studies show that the ghrelin/obestatin ratio is modified in anorexia nervosa and obesity. This suggests that the ghrelin/obestatin balance could be essential to adapt the body's response to nutritional challenges. Although measuring ghrelin and obestatin in plasma is challenging because many forms of the peptides circulate, more sensitive and selective assays to detect the different preproghrelin-derived peptides are being developed and may be the key to obtaining a better understanding of their roles in different physiological and pathological conditions. [source] Antigenic variation with a twist , the Borrelia storyMOLECULAR MICROBIOLOGY, Issue 6 2006Steven J. Norris Summary A common mechanism of immune evasion in pathogenic bacteria and protozoa is antigenic variation, in which genetic or epigenetic changes result in rapid, sequential shifts in a surface-exposed antigen. In this issue of Molecular Microbiology, Dai et al. provide the most complete description to date of the vlp/vsp antigenic variation system of the relapsing fever spirochaete, Borrelia hermsii. This elaborate, plasmid-encoded system involves an expression site that can acquire either variable large protein (vlp) or variable small protein (vsp) surface lipoprotein genes from 59 different archival copies. The archival vlp and vsp genes are arranged in clusters on at least five different plasmids. Gene conversion occurs through recombination events at upstream homology sequences (UHS) found in each gene copy, and at downstream homology sequences (DHS) found periodically among the vlp/vsp archival genes. Previous studies have shown that antigenic variation in relapsing fever Borrelia not only permits the evasion of host antibody responses, but can also result in changes in neurotropism and other pathogenic properties. The vlsE antigenic variation locus of Lyme disease spirochaetes, although similar in sequence to the relapsing fever vlp genes, has evolved a completely different antigenic variation mechanism involving segmental recombination from a contiguous array of vls silent cassettes. These two systems thus appear to represent divergence from a common precursor followed by functional convergence to create two distinct antigenic variation processes. [source] The synthesis and accumulation of stearidonic acid in transgenic plants: a novel source of ,heart-healthy' omega-3 fatty acidsPLANT BIOTECHNOLOGY JOURNAL, Issue 7 2009Noemí Ruiz-López Summary Dietary omega-3 polyunsaturated fatty acids have a proven role in reducing the risk of cardiovascular disease and precursor disease states such as metabolic syndrome. Although most studies have focussed on the predominant omega-3 fatty acids found in fish oils (eicosapentaenoic acid and docosahexaenoic acid), recent evidence suggests similar health benefits from their common precursor, stearidonic acid. Stearidonic acid is a ,6-unsaturated C18 omega-3 fatty acid present in a few plant species (mainly the Boraginaceae and Primulaceae) reflecting the general absence of ,6-desaturation from higher plants. Using a ,6-desaturase from Primula vialii, we generated transgenic Arabidopsis and linseed lines accumulating stearidonic acid in their seed lipids. Significantly, the P. vialii,6-desaturase specifically only utilises ,-linolenic acid as a substrate, resulting in the accumulation of stearidonic acid but not omega-6 ,-linolenic acid. Detailed lipid analysis revealed the accumulation of stearidonic acid in neutral lipids such as triacylglycerol but an absence from the acyl-CoA pool. In the case of linseed, the achieved levels of stearidonic acid (13.4% of triacylglycerols) are very similar to those found in the sole natural commercial plant source (Echium spp.) or transgenic soybean oil. However, both those latter oils contain ,-linolenic acid, which is not normally present in fish oils and considered undesirable for heart-healthy applications. By contrast, the stearidonic acid-enriched linseed oil is essentially devoid of this fatty acid. Moreover, the overall omega-3/omega-6 ratio for this modified linseed oil is also significantly higher. Thus, this nutritionally enhanced linseed oil may have superior health-beneficial properties. [source] A Stereodivergent Synthesis of All Stereoisomers of Centrolobine: Control of Selectivity by a Protecting-Group ManipulationCHEMISTRY - A EUROPEAN JOURNAL, Issue 44 2009Bernd Schmidt Prof. Abstract All stereoisomers of the natural product centrolobine are selectively synthesized, by starting from a common precursor. Key steps are an enantioselective allylation with enantiomerically pure allylsilanes, a tandem ring-closing metathesis,isomerization reaction, and a Heck reaction by using an arene diazonium salt. By choosing appropriate conditions for the final deprotection step, either the cis -configured centrolobines or their epimers are selectively obtained. [source] The role of pneumolysin in pneumococcal pneumonia and meningitisCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2004R. A. HIRST SUMMARY Diseases caused by Streptococcus pneumoniae include pneumonia, septicaemia and meningitis. All these are associated with high morbidity and mortality. The pneumococcus can colonize the nasopharynx, and this can be a prelude to bronchopneumonia and invasion of the vasculature space. Proliferation in the blood can result in a breach of the blood,brain barrier and entry into the cerebrospinal fluid (CSF) where the bacteria cause inflammation of the meningeal membranes resulting in meningitis. The infected host may develop septicaemia and/or meningitis secondary to bronchopneumonia. Also septicaemia is a common precursor of meningitis. The mechanisms surrounding the sequence of infection are unknown, but will be dependent on the properties of both the host and bacterium. Treatment of these diseases with antibiotics leads to clearance of the bacteria from the infected tissues, but the bacteriolytic nature of antibiotics leads to an acute release of bacterial toxins and thus after antibiotic therapy the patients can be left with organ-specific deficits. One of the main toxins released from pneumococci is the membrane pore forming toxin pneumolysin. Here we review the extensive studies on the role of pneumolysin in the pathogenesis of pneumococcal diseases. [source] Building a consensus regarding the nature and origin of mesenchymal stem cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S38 2002Donald G. PhinneyArticle first published online: 23 APR 200 Abstract Mesenchymal stem cells (MSCs) are believed to be the common precursors to differentiated cell lineages found in bone and bone marrow, including adipocytes, chondrocytes, osteoblasts, and hematopoiesis-supporting stroma. Apart from this fact, most aspects of MSC biology, including their ontogeny, anatomical location in marrow, and in vivo functions remain vague. Attempts to clarify these issues have produced confounding results, principally due to the fact that many researchers employ different methods to culture MSCs, assess their differentiation potential, and evaluate their capacity for self-renewal. Accordingly, the current status of the field appears fragmentary with no clear consensus on how to define the cells. In describing past and present contributions to the field of MSC research, I will demonstrate that the apparent incongruity of the literature is misleading, and that an unbiased interpretation reveals a fairly cohesive picture of MSC biology. J. Cell. Biochem. Suppl. 38: 7,12, 2002. © 2002 Wiley-Liss, Inc. [source] Spatial association of photosynthesis and chemical defense in Arabidopsis thaliana following herbivory by Trichoplusia niPHYSIOLOGIA PLANTARUM, Issue 2 2009Jennie Tang Because they share common precursors and require significant amounts of energy, photosynthesis and defense against herbivores and pathogens may be inversely related. This relationship was examined in Arabidopsis thaliana exposed to herbivory by Trichoplusia ni neonates. The spatial pattern of photosynthesis was compared statistically with that of induction of the defense-related cinnamate-4-hydroxylase (C4H) gene across individual leaves exposed to herbivory in transgenic plants harboring a C4H:GUS gene fusion. In portions of the leaf where C4H:GUS expression was upregulated, photosynthesis was depressed, while non-photochemical quenching was increased, suggesting a trade-off between these two processes. However, photosynthetic damage spread further into surrounding areas than the induction of C4H:GUS expression. Photosynthetic depression was observed up to 1 mm from the edges of holes, whereas C4H:GUS induction typically was limited to about 0.5 mm or less from edges. Other mechanisms may be responsible for the spread of photosynthetic damage beyond where C4H-related defense was induced. Alternatively, C4H induction may reflect a subset of defensive responses more limited in their spatial distribution than the downregulation of photosynthesis. The suppression of photosynthesis in remaining leaf tissue represents a ,hidden cost' of herbivore damage. [source] Diversity-Oriented Approach to Biologically Relevant Molecular Frameworks Starting with ,-Naphthol and Using the Claisen Rearrangement and Olefin Metathesis as Key StepsCHEMISTRY - A EUROPEAN JOURNAL, Issue 31 2006Sambasivarao Kotha Prof. Dr. Abstract A diversity-oriented approach for the synthesis of various structurally different molecular frameworks from readily accessible and common precursors is described. A Claisen rearrangement followed by ring-closing metathesis or ethylene-promoted ring-closing enyne metathesis has been utilized as the key synthetic transformation to generate naphthoxepine derivatives. The ring-closing metathesis approach has also been used to generate spirocyclic compounds and the pleiadene framework. [source] |