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Excellent Starting Point (excellent + starting_point)
Selected AbstractsAnalysis of the Voltammetric Response of Electroactive Guests in the Presence of Non-Electroactive Hosts at Moderate ConcentrationsELECTROANALYSIS, Issue 18 2004Sandra Mendoza Abstract In this work, we present a method to analyze the voltammetric response of reversible redox systems involving molecules that, bearing m non-interactive electroactive sites, can undergo fast complexation equilibria with host molecules present at concentrations of the same order of magnitude as those of the electroactive guest. The approach focuses on systems for which the relative values of the binding constants for the oxidized and reduced forms of the guest result in the displacement of the voltammetric response of the electroactive molecule as the concentration of the host is increased in the electrolytic solution. This behavior is commonly known as "one wave shift behavior". Based on a series of assumptions, the method allows calculation of all the thermodynamic parameters that describe the electrochemical and complexation equilibria of a given host-guest system. The main strength of the suggested method, however, relies on the fact that it only requires cyclic voltammetry data and that it can be used for systems in which large concentrations of the host can not be employed either due to important changes of the ionic strength or to solubility problems. Although the accuracy of the obtained information is limited by the quality of the data provided by the technique, and by the assumptions employed, it certainly represents an excellent starting point for subsequent refinement either using digital simulations or an independent experimental technique. [source] Identification of a Chr 11 quantitative trait locus that modulates proliferation in the rostral migratory stream of the adult mouse brainEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2010Anna Poon Abstract Neuron production takes place continuously in the rostral migratory stream (RMS) of the adult mammalian brain. The molecular mechanisms that regulate progenitor cell division and differentiation in the RMS remain largely unknown. Here, we surveyed the mouse genome in an unbiased manner to identify candidate gene loci that regulate proliferation in the adult RMS. We quantified neurogenesis in adult C57BL/6J and A/J mice, and 27 recombinant inbred lines derived from those parental strains. We showed that the A/J RMS had greater numbers of bromodeoxyuridine-labeled cells than that of C57BL/6J mice with similar cell cycle parameters, indicating that the differences in the number of bromodeoxyuridine-positive cells reflected the number of proliferating cells between the strains. AXB and BXA recombinant inbred strains demonstrated even greater variation in the numbers of proliferating cells. Genome-wide mapping of this trait revealed that chromosome 11 harbors a significant quantitative trait locus at 116.75 ± 0.75 Mb that affects cell proliferation in the adult RMS. The genomic regions that influence RMS proliferation did not overlap with genomic regions regulating proliferation in the adult subgranular zone of the hippocampal dentate gyrus. On the contrary, a different, suggestive locus that modulates cell proliferation in the subgranular zone was mapped to chromosome 3 at 102 ± 7 Mb. A subset of genes in the chromosome 11 quantitative trait locus region is associated with neurogenesis and cell proliferation. Our findings provide new insights into the genetic control of neural proliferation and an excellent starting point to identify genes critical to this process. [source] The development of biocommodities and the role of North West European ports in biomass chainsBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 3 2009Johan P. M. Sanders Abstract Biomass-derived commodities will compete with commodities derived from fossil fuels in 20 years' time. This perspective will explore the economic conditions that will govern the development of, and the trade in these biocommodities. Markets for biocommodities will open up new revenues for both the agricultural and the chemical sector. We shall explore the importance of the biorefinery concept for the establishment of these new markets. Biorefinery is the sustainable processing of biomass into a spectrum of marketable products and energy. Trade in biobased substances will be greatly enhance if standard ,commodities' are defined and produced in several places in the world. Now we turn to the second question of this perspective: where will biocommodities be produced and where will they be used? The choice of where to process the biomass will depend on the type of biomass, transport distances, bulk density, decay rate, ease of handling, the type of process(ses), the presence of markets, the cost of labor, and logistical conditions. Ports, both on the exporting side and on the importing side, will have a major influence on the formation of biomass chains. In export ports, crude or partially pre-treated biomass will be collected and processed/ transformed into a biocommodity. Existing industries, such as feed production, can be combined with the production of biocommodities, The role of port areas and chemical industries in several biomass chains are shown. The combination of a major port and major application markets for biomass, such as feed industry, chemical industry, biofuels industry and power generation, will allow for the formation of a biomass hub. The formation of a biomass hub will be a step-by-step process in which services and exchange markets are added to existing logistical and industrial structures. The port of Rotterdam has an excellent starting point to become a hub in international biomass trade and processing. In the near future, 5,15 years from now, international biomass trade will become standardized and biocommodities will be defined, partly on the basis of technologies still in development. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Design of a pH-sensitive pore-forming peptide with improved performanceCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2004D.H. Haas Abstract:, GALA is a 30 residue synthetic peptide designed to interact with membranes in a pH-sensitive manner, with potential applications for intracellular drug and gene delivery. Upon reduction of the pH from neutral to acidic, GALA switches from random coil to , -helix, inserts into lipid bilayers, and forms oligomeric pores of defined size. Its simple sequence and well-characterized behavior make the peptide an excellent starting point to explore the effects of sequence on structure, pH sensitivity, and membrane affinity. We describe synthesis and characterization of two derivatives of GALA, termed GALAdel3E and YALA. GALAdel3E has a deletion of three centrally located glutamate residues from GALA, while YALA replaces one glutamate residue with the unusual amino acid 3,5-diiodotyrosine. Both derived peptides retain pH sensitivity, showing no ability to cause leakage of an encapsulated dye from unilamellar vesicles at pH 7.4 but substantial activity at pH 5. Unlike GALA, neither peptide undergoes a conformational change upon reduction of the pH, remaining , -helical throughout. Interestingly, the pH at which the peptides activate is shifted, with GALA becoming active at pH ,5.7, GALAdel3E at pH ,6.2, and YALA at pH ,6.7. Furthermore, the peptides GALAdel3E and YALA show improved activity compared with GALA for cholesterol-containing membranes, with YALA retaining the greatest activity. Improved activity in the presence of cholesterol and onset of activity in the critical range between pH 6 and 7 may make these peptides useful in applications requiring intracellular delivery of macromolecules, such as gene delivery or anti-cancer treatments. [source] | |||||||||||||