18 research outputs found
What Lies Beyond Service Delivery - An Australian Perspective
No full textCo-published simultaneously as Journal of political marketing, v. 2, no. 3/4 2003.Karin Geiselhart, Mary Griffiths, Bronwen Fitzgeral
Characterization of solid dispersions of carbamazepine and PEG6000/vinylcaprolactam/vinylacetate copolymer
No full textPurpose.
to investigate the solid-state properties and dissolution performances of solid dispersions of carbamazepine and a new
marketed copolymer proposed for hot melt extrusion.
Methods.
Physical mixtures [PM] were prepared by mixing in mortar and pestle for 10 min carbamazepine [CBZ, polymorphic form
III] and PEG6000/vinylcaprolactam/vinylacetate copolymer (Soluplus® BASF) in various drug/polymer ratios (1:9, 3:7, 1:1,
7:3 w/w). Co-melted formulations [CM] were prepared by heating the PM at 170°C on a hot plate for 15 min, allowing to cool at room temperature and grinding the resulting glasses in a mortar. PXRD study, DSC analysis and dissolution test
(paddle apparatus, 500mL of 0.0125% SLS solution, 37±0.5°C, 100 rpm, UV detection at 287 nm) were performed on all samples.
Results.
drug-polymer solid-state interaction, resulting in complete loss of CBZ crystallinity was found to occur in CM with
drug/polymer ratios 1:9 and 3:7 w/w. Accordingly, the glass transition recorded for these dispersions was lowered with
respect to that of the pure polymer. Non-interacted crystalline CBZ was detected in all PM as well as in 1:1 and 7:3 CM
formulations. Furthermore, non-interacted amorphous CBZ was thought to be present in the 7:3 CM formulation, resulting in
drug crystallization up on heating in the DSC experiment. As far as dissolution properties are concerned, PM presented
similar or only slightly higher dissolution rate with respect to the pure drug, whilst 1:9 and 3:7 CMF demonstrated a remarkable improvement of dissolution rate (the amount dissolved at t=10min doubled that of the pure CBZ). The 7:3 CM formulation was affected by a decreased dissolution rate probably caused by the formation of CBZ hydrate during the test.
Conclusion.
solid dispersion of CBZ with a new PEG6000/vinylcaprolactam/vinylacetate copolymer can be successfully prepared by comelting method, resulting in a high degree of drug-polymer interaction and consequently a remarkable improvement of drug
dissolution rate
Evaluation of a new polymer for the preparation of solid dispersion of poorly soluble drugs
No full textBILIPROTEINS FROM THE BUTTERFLY Pieris brassicae STUDIED BY TIME-RESOLVED FLUORESCENCE AND COHERENT ANTI-STOKES RAMAN SPECTROSCOPY
No full textThe fluorescence decay time of the biliverdin IX7 chromophore present in biliproteins isolated from Pieris brassicae is determined to be 44 ± 3 ps. This value suggests a cyclic helical chromophore structure. The vibrational frequencies determined by CARS-spectroscopy are compared with those of model compounds. The data confirm that the chromophore in the protein-bound state adopts a cyclic-helical, flexible conformation
Picosecond time-resolved fluorescence of phycobiliproteins
No full textThe α- and β-subunits of C-phycocyanin from Mastigocladus laminosus were prepared according to revised procedures. Both subunits are isolated as dimers, which can be dissociated into monomers with detergent mixtures. The fluorescence decay kinetics are similar for the respective monomers and dimers. In no case could they be fitted by only one (α-subunit) or two exponentials (β-subunit) which are predicted by theory for samples with a unique chromophore—protein arrangement containing one and two chromophores, respectively. It is suggested that there exists a heterogeneity among the chromophores of the subunits, which may persist in the highly aggregated complexes present in cyanobacterial antennas
Global Governance as a Complex Adaptive System
No full textThe recent advent of Internet technologies has greatly intensified existing globalization processes. The development of full multimedia international communications has the potential to democratize information flows. Citizens can communicate with each other and with governments to create and document public and private accountabilities beyond jurisdictional borders. Ironically, it is also now possible to achieve intensive and intrusive surveillance of individuals and organisations, virtually untraceable criminal exchanges of data, and even forms of cyberwarfare. These possibilities are all part of the global information commons. Like physical common spaces, beneficial and nefarious elements coexist. A working definition of the global information commons is the set of all information systems critical to managing global resources and governance, and the set of protocols for their exchange. While both cumbersome and broad, this definition of the global information commons helps to ground it as a concept that can be modelled and managed. It responds to Dahl’s query about the possibility of a third transformation of democracy beyond the nation-state. This article considers key issues for the emerging global information commons. These relate to the role of new technologies in possible forms of global governance. Global governance is here considered to be the emerging mechanisms for managing trans-national issues and resources. These can be particular to a specific issue or resource, such as the fisheries, or may be more formal, such as the European Union. Governance can be seen as a management function, much as the “governors” on early steam trains. First, the author presents an overview of technology as socially determined, followed by a sketch of how global governance may be seen as a complex adaptive system. This includes an analysis of how models might embed democratic structures. Finally, examples of sub-systems of the global information commons demonstrate the range of actors and rules such a system would need to consider. This theoretical perspective builds on empirical work in the physical, biological, and social sciences and emphasizes the value of modelling governance at all scales. This approach is seen as fruitful for identifying and monitoring dynamic patterns. It provides useful insights for managing the global information commons. In human systems, the rules of interaction and information exchange are determined by the values of the actors (Theys, 1998). Modelling can help to articulate these values. In complex human systems, the direction of change can be as important as absolute measures.</jats:p
N-terminally myristoylated feline foamy virus Gag allows Env-independent budding of sub-viral particles
No full textFoamy viruses (FVs) are distinct retroviruses classified as Spumaretrovirinae in contrast to the other retroviruses, the Orthoretrovirinae. As a unique feature of FVs, Gag is not sufficient for sub-viral particle (SVP) release. In primate and feline FVs (PFV and FFV), particle budding completely depends on the cognate FV Env glycoproteins. It was recently shown that an artificially added N-terminal Gag myristoylation signal (myr-signal) overcomes this restriction in PFV inducing an Orthoretrovirus-like budding phenotype. Here we show that engineered, heterologous N-terminal myr-signals also induce budding of the distantly related FFV Gag. The budding efficiency depends on the myr-signal and its location relative to the N-terminus of Gag. When the first nine amino acid residues of FFV Gag were replaced by known myr-signals, the budding efficiency as determined by the detection of extracellular SVPs was low. In contrast, adding myr-signals to the intact N-terminus of FFV Gag resulted in a more efficient SVP release. Importantly, budding of myr-Gag proteins was sensitive towards inhibition of cellular N-myristoyltransferases. As expected, the addition or insertion of myr-signals that allowed Env-independent budding of FFV SVPs also retargeted Gag to plasma membrane-proximal sites and other intracellular membrane compartments. The data confirm that membrane-targeted FV Gag has the capacity of SVP formation
A Comparison of Phycocyanins from Three Different Species of Cyanobacteria Employing Resonance-Enhanced Coherent Anti-Stokes Raman Spectroscopy
No full textResonance-enhanced coherent anti-Stokes Raman spectra are recorded for monomers and trimers of phycocyanin from three different cyanobacteria: Westiellopsis prolifica, Mastigocladus laminosus and Spirulina platensis. It is shown that upon aggregation from monomer to trimer the electronic structures of both the α84 and β84 chromophores are changed. The spectra of the trimers originating from S. platensis and M. laminosus are very similar to each other, but distinctly different from the spectrum of W. prolifica
