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Increased Selectivity (increased + selectivity)
Selected AbstractsAre aid agencies improving?ECONOMIC POLICY, Issue 52 2007William Easterly SUMMARY Are aid agencies improving? The record of the aid agencies over time seems to indicate weak evidence of progress in response to learning from experience, new knowledge, or changes in political climate. The few positive results are an increased sensitivity to per capita income of the recipient (although it happened long ago), a decline in the share of food aid, and a decline in aid tying. Most of the other evidence , increasing donor fragmentation, unchanged emphasis on technical assistance, little or no sign of increased selectivity with respect to policies and institutions, the adjustment lending-debt relief imbroglio , suggests an unchanged status quo, lack of response to new knowledge, and repetition of past mistakes. , William Easterly [source] Competitive coordination between lead and oligoelements with respect to some therapeutic heavy-metal chelatorsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2008C. Gourlaouen Abstract The competitive complexation of Ca2+, Fe2+, Cu2+, Zn2+, and Pb2+ toward ethylene diamine tetraacetate (EDTA), dimercaprol and D -penicillamine, three liganding agents commonly used in chelation therapy against heavy metal, especially lead, poisonings is examined by means of B3LYP calculations, natural population analyses, and the topological analysis of the electron localization function. It is shown that Pb2+ can displace any of Ca2+, Fe2+, Cu2+, or Zn2+ chelated by any of dimercaprol or D -penicillamine, but can only displace Ca2+ if EDTA is concerned. The first two chelators thus appear as better entities than EDTA to be used in chelation therapy, where in vivo selective complexation is essential. Moreover, the comparison of the bonding characteristics of Pb2+ with those of the other cations allows deriving three features to be taken into account in designing new chelators expecting to have an increased selectivity toward this cation. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Selection favours low hsp70 levels in chronically metal-stressed soil arthropodsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2000KÖhler Thirty-eight populations of woodlice (Oniscus asellus, Porcellio scaber) and millipedes (Julus scandinavius) from 28 differently metal-polluted field sites were analysed for their 70-kDa stress protein (hsp70) level. Although ANOVA revealed significant dependence of the hsp70 level on the concentrations of water-soluble lead, cadmium and zinc and the soil pH, each of these parameters accounted for at most 18% of the intersite variability of the stress protein level only. A multivariate model based on multiple regression analysis explained more than 96% of hsp70 variance and revealed both the pollution history of a site (strong metal contamination for more than 70 years) and invertebrate species identity to act as the most important parameters. The model accounted for the observation that most of the populations from long-term polluted sites exhibited comparatively low stress protein levels in response to their own (contaminated) habitats. In contrast, isopods (O. asellus) from a control site were not able to maintain a low hsp70 level when they were exposed to either an artificial metal cocktail or soil taken from one of the contaminated field sites. They did not acclimatize to the exposure conditions within 3 months. We propose that selection of insensitive phenotypes in long-term polluted soils has taken place so as to minimize the stress protein level which, in turn, is indicative of high intracellular protein integrity. Long-term selection for a high hsp70 level to compensate for adverse metal impact was not observed, which suggests that such a strategy may trade off against other fitness consequences. In this context, insensitivity to metal stress involved increased selectivity in food choice and reduced variability in stress response. Multiple regression models showed species-specificity in those abiotic factors which determined (1) high hsp70 levels in sensitive populations as well as (2) low hsp70 levels in insensitive ones. Therefore, abiotic factors can be assigned to act as the main components of selection: lead and cadmium for J. scandinavius and O. asellus, zinc for P. scaber. [source] Alternative drug delivery approaches for the therapy of inflammatory bowel diseaseJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Yvette Meissner Abstract This article shall give an overview on drug delivery systems for new therapeutic strategies in the treatment of inflammatory bowel disease. The various features of the different approaches allowing locally restricted drug delivery to the inflamed colon are discussed including the main physiological and pathophysiological limitations for the different systems. Conventional drug delivery systems are tightly adapted from developments for colonic delivery by oral administration triggered by release mechanisms owing to the physiological environment that these systems encounter in the colonic region. The newer developments in this context aim for an increased selectivity of drug delivery by targeting mechanisms which have a closer relation to pathophysiological particularities of the disease. Therefore, we were focused especially on new strategies for such treatment including liposomal formulations, cyclodextrins, micro- or nanoparticles, viral gene therapy approaches, and others. Effective and selective delivery even of an otherwise nonspecifically acting drug could provide new therapeutic pathways in the treatment of inflammatory bowel disease. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 2878,2891, 2008 [source] A flexible approach to the design of new potent substance P receptor ligandsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2001R. Millet The development of small-molecule antagonists of the substance-P-preferring tachykinin NK1 receptor offers an excellent opportunity to exploit these molecules as novel therapeutic agents in diverse pathologies such as depression, emesis or asthma. GR71251 has previously been identified as a potent and selective substance-P-receptor antagonist. We have therefore undertaken the synthesis of new pseudopeptidic analogues based on the C-terminal sequence of GR71251. The evaluation of binding affinities toward NK1 and NK2 receptors has enabled us to propose new selective NK1 ligands with high affinity. Structure-activity relationships showed that the Trp-OBzl(CF3)2 moiety is essential for NK1 affinity and that the introduction of building units such as spirolactam, lactam or proline, leading to a constrained peptide, increased selectivity for NK1 receptors. These compounds constitute a useful starting point for new substance P antagonists and represent an attractive lead series for further studies on the design of specific NK1 antagonists. [source] Methyltrioxorhenium Catalysis in Nonconventional Solvents: A Great Catalyst in a Safe Reaction MediumCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 5 2010Marcello Crucianelli Dr. Abstract The requirement that chemical processes are sustainabable, reflected in waste reduction and the use of safe reagents and reaction conditions, is becoming even more stringent as a result of pressure by society and governments to preserve the environment and protect human health. Catalysis offers numerous benefits related to green chemistry, including lowered energetic reaction requirements; catalytic, rather than stoichiometric, amounts of materials; increased selectivity; lowered consumption of processing and separation agents; and, in many cases, the use of less-toxic compounds. Our research group has for a long time been studying methyltrioxorhenium in the oxyfunctionalization of different substrates, by using H2O2 or its urea-hydrogen peroxide complex as the primary oxidant. In this Review paper we aim to provide a full literature account on the catalytic activity and selectivity of methyltrioxorhenium in the oxyfunctionalization reaction, either in nonconventional solvents or under solvent-free conditions, with a particular emphasis on the use of ionic liquids as green reaction media. [source] Acceleration of Suzuki,Miyaura- and Stille-type Coupling Reactions by Irradiation with Near-UV-A LightCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 12 2008Giovanni Imperato Dr. Abstract Irradiation of a palladium catalyst bearing UV-A-absorbing phosphine ligands with low-intensity UV-A light leads to higher conversions of reactants at lower temperatures and an increased selectivity towards the cross-coupling product in Suzuki,Miyaura- and Stille-type reactions. The examples studied illustrate that a selective energy input into the catalyst by irradiation leads to more selective conversions under milder reaction conditions. With the availability of affordable and energy-efficient UV-A LED light sources, selective heating of the catalyst by light can be envisaged as a general strategy to increase the performance of a catalyst. [source] | ||||||||||