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First Preparation (first + preparation)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Nucleotide-binding domain 1 of cystic fibrosis transmembrane conductance regulator

FEBS JOURNAL, Issue 17 2000
Production of a suitable protein for structural studies
Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). This protein belongs to the large ATP-binding cassette (ABC) family of transporters. Most patients with cystic fibrosis bear a mutation in the nucleotide-binding domain 1 (NBD1) of CFTR, which plays a key role in the activation of the channel function of CFTR. Determination of the three dimensional structure of NBD1 is essential to better understand its structure,function relationship, and relate it to the biological features of CFTR. In this paper, we report the first preparation of recombinant His-tagged NBD1, as a soluble, stable and isolated domain. The method avoids the use of renaturing processes or fusion constructs. ATPase activity assays show that the recombinant domain is functional. Using tryptophan intrinsic fluorescence, we point out that the local conformation, in the region of the most frequent mutation ,F508, could differ from that of the nucleotide-binding subunit of histidine permease, the only available ABC structure. We have undertaken three dimensional structure determination of NBD1, and the first two dimensional 15N- 1H NMR spectra demonstrate that the domain is folded. The method should be applicable to the structural studies of NBD2 or of other NBDs from different ABC proteins of major biological interest, such as multidrug resistance protein 1 or multidrug resistance associated protein 1. [source]

980-nm Laser-Driven Photovoltaic Cells Based on Rare-Earth Up-Converting Phosphors for Biomedical Applications

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
Zhigang Chen
Abstract A prerequisite for designing and constructing wireless biological nanorobots is to obtain an electrical source that is continuously available in the operational biological environment. Herein the first preparation of 980-nm laser-driven photovoltaic cells (980LD-PVCs) by introducing of a film of rare-earth up-converting nanophosphors in conventional dye-sensitized solar cells is reported. Under the irradiation of a 980-nm laser with a power of 1,W, the visible up-converting luminescence of rare-earth nanophosphors can be efficiently absorbed by the dyes in 980LD-PVCs so that they exhibit a maximal output power of 0.47 mW. In particular, after being covered with 1 to 6 layers of pig intestines (thickness: ca. 1,mm per layer) as a model of biological tissues, 980LD-PVCs still possess a maximal output power of between 0.28 and 0.02,mW, which is efficient enough to drive many kinds of biodevices. This research opens up the possibility of preparing and/or developing novel electrical sources for wireless biological nanorobots and many other biodevices. [source]

Graft copolymers of methyl methacrylate and poly([R]-3-hydroxybutyrate) macromonomers as candidates for inclusion in acrylic bone cement formulations: Compression testing

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2006
Sophie Nguyen
Abstract Graft copolymers of methyl methacrylate and biodegradable, biocompatible bacterial poly([R]-3-hydroxybutyrate) (PHB) blocks were synthesized and evaluated as possible constituents in acrylic bone cements for use in orthopaedic applications. The copolymers were produced by conventional free radical copolymerization and incorporated in one commercially available acrylic bone cement brand, Antibiotic Simplex® (AKZ). Cements with formulations containing 6.7 and 13.5 wt % of PMMA- graft -PHB were prepared. The morphology of the graft copolymer particles was suggested to influence the ability of the modified cement to be processed. Formulations containing more than about 20 wt % of the graft copolymer resulted in cement doughs that, both after first preparation and several hours later, were either sandy or soft spongy in texture and, thus, would be unacceptable for use in orthopaedic applications. The morphologies of the powders and the volumetric porosity (p) and ultimate compressive strength (UCS) of the cured cements were determined. Micro computed tomography showed that the cements presented average porosities of 13.5,16.9%. It was found that, while the powder particle shape and size for the experimental cements were markedly different from those of AKZ, there was no significant difference in either p or UCS for these cements. The latter was determined to be about 85 MPa for the modified cements and 84 MPa for Antibiotic Simplex. Furthermore, the UCS of all the cements exceeded the minimum level for acrylic bone cements, as stipulated by ASTM F-451. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source]

The use of Butea superba (Roxb.) compared to sildenafil for treating erectile dysfunction

BJU INTERNATIONAL, Issue 2 2010
Jeff R. Cortés-González
Study Type , Therapy (case control) Level of Evidence 3b OBJECTIVE To evaluate the effect of an extract of Butea superba (Roxb.) (BS) compared to sildenafil for treating erectile dysfunction (ED). PATIENTS AND METHODS An open label study was carried out among 32 men with organic ED to evaluate the response on the International Index of Erectile Function 5 (IIEF-5) to BS, a ,natural health' product (100 mg), compared to 50 mg of sildenafil (a phosphodiesterase-5 inhibitor). After a 1-week wash-out, responders to BS received either 100 mg starch or 100 mg of another batch of BS (double-blind). RESULTS Of the patients in the BS group, 27 (84%) responded positively, compared with 26 (81%) in the sildenafil group. When assessing the score alone, 12 (38%) had a better score after taking BS, compared to seven (22%) after sildenafil, and eight (25%) had the same score. The results were surprising and could not be repeated in the double-blind part of the study, where no effect of BS was recorded. CONCLUSIONS A ,natural' health product containing BS was more effective than sildenafil in the first part of the study, but in the second, using another batch of BS, the positive result could not be repeated and no effect was recorded. The conclusion is that the first preparation of BS was most likely blended with a phosphodiesterase-5 inhibitor, later confirmed by the supplier of BS (a natural health products company) after their own analysis. [source]