摘要:

Copolymers composed of sulfonylurea(SU) as an antagonist of ATP-sensitive K+channel and sugar moieties as double ligands were synthesized. Insulin secretion from MIN6 cells(insulinoma cell line) in contact with the copolymers was evaluated. MIN6 cells attached to the poly(N-p-vinylbenzyl-D-maltonamide-co-SU) [P(VMA-co-SU)]-coated dishes were in the more aggregated form as compared to other polymer-coated surfaces. By introducing SU into the sugar bearing homopolymer, an enhanced effect on insulin secretion from MIN6 cells was observed due to the specific interaction between SU ligands and SU receptors on the β-cell membrane. P(VMA-coSU) composed of SU and non-reducing glucose moieties demonstrated enhanced insulin secretion from MIN6 cells and faster proliferation of MIN6 cells as compared to poly(N-p-vinylbenzyl-D-lactonamide-co-SU) [P(VLA-co-SU)] probably owing to the glucose transporters presence on the MIN6 cell membrane. Insulin secretion from MIN6 cells pretreated with diazoxide as an agonist of ATP-sensitive K+channel was suppressed.

ISSN:0920-5063    

DOI:10.1163/156856200744093

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In vivoprofile of vascular endothelial growth factor (VEGF) release from collagen hydrogels was investigated comparing that of hydrogel degradation while angiogenesis induced by the released VEGF was assessed. Collagen sponges were chemically cross-linked with different amounts of glutaraldehyde for various time periods. When125I-labeled collagen hydrogels incorporating VEGF were subcutaneously implanted into the back subcutis of mice, the hydrogel radioactivity decreased with time, the decrement profile depending on the cross-linking conditions. The radioactivity was retained for longer time periods as the glutaraldehyde concentration and cross-linking time increased. Implantation study of collagen hydrogels incorporating125I-labeled VEGF revealed that the remaining VEGF radioactivity decreased with time and the retention period was prolonged with the decreased hydrogel biodegradation. The slower the hydrogel degradation, the longer the period of VEGF retention. The collagen hydrogel incorporating VEGF induced significant angiogenesis around the implanted hydrogel, in marked contrast to VEGF in the solution form and VEGF-free empty hydrogel. The retention period of angiogenesis became longer with a decrease of thein vivodegradation rate of hydrogels. It is possible that the slower degraded hydrogel achieves a longer period of VEGF release, resulting in prolonged angiogenetic effect. We concluded that in our hydrogel system, biologically active VEGF was released as a result ofin vivodegradation of the hydrogel.

ISSN:0920-5063    

DOI:10.1163/156856200744101

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The covalent grafting of a 35-base poly(thymidylic) acid(dT35) onto aminated polystyrene latex has been studied. The oligonucleotide was activated by 1,4-phenylene diisothiocyanate (PDC) prior to grafting reaction. The influence of various experimental conditions related either to the medium (pH, ionic strength) or to the latex (nature and surface charge density, presence of adsorbed nonionic surfactant) was studied. Discrimination between covalent grafting and adsorption was achieved by desorbing the non-covalently grafted dT35induced by consecutive washings with a suitable buffer solution. The amount of covalently grafted oligonucleotide directly correlated to the concentration and accessible functional groups at the particle surface.

ISSN:0920-5063    

DOI:10.1163/156856200744110

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Anin vitrosystem for evaluating the safety of tissue-engineered products is a convenient because of its rapidity and low cost. On the basis of recent studies, intercellular channels called gap-junctions are considered to play an important role on the tumor-promotion stage during the tumorigenesis induced by polyurethanes. Further, we also demonstrate the significance of the intercellular communication during neuronal cell differentiation. From these results, we propose a survey of the function of the gap-junctional communication as a probable useful marker for evaluating the safety of tissue-engineered products.

ISSN:0920-5063    

DOI:10.1163/156856200744129

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Polymethylmethacrylate intraocular lenses (IOLs) were surface-modified by the linking of a overlayer of hyaluronan.In vitroexperiments show that the hydrophilic HA overlayer prevents fibroblasts adhesion and greatly reducesStaphyloccous epidermidisadhesion to the IOL surface. To gain insights into the interfacial properties of untreated and hyaluronan-coated PMMA IOLs, force-distance curves were obtained by atomic force microscopy, using standard and modified tips. These measurements allow clear appreciation of the marked difference between the mechanical and chemico-physical properties at the aqueous interface of the uncoated and hyaluronan-coated lenses.

ISSN:0920-5063    

DOI:10.1163/156856200744138

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A bioactive poly(β-hydroxyalkanoate) derived from malic acid was prepared and tested on bone repair and muscle regeneration. This functionalized and hydrolyzable polymer was obtained after several steps, the first one being the anionic copolymerization of three malolactonic acid esters. Chemical modifications were carried out on the terpolymer to turn benzyl-protecting groups into carboxyl groups and allyl groups into sulfonate groups. The resulting polymer bore carboxylate, sulfonate, and sec-butyl pendent groups in 65/25/10 molar proportions and were aimed at interacting with heparan binding growth factors. This polymer did not present any toxic effect in cell viability of HepG2cells, over a large range of concentrations (0.01-0.25 mg l-1). Its ability to improve wound healing was testedin vivoand positive results are reported. Furthermore, the bioactivity of this polymer was evaluated using the regeneration model ofExtensor digitorum longus(EDL) rat muscle. The study displayed a significant increase in the muscle regeneration and maturation.

ISSN:0920-5063    

DOI:10.1163/156856200744147

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Experimental conditions for the fabrication of two new polymeric devices (i.e. films and slabs) useful for the controlled release of recombinant growth hormone (GH) are given. The release rate is controlled by the resorption profile of the vinylpyrrolidone-hydroxyethyl methacrylate (VPHEMA) tested systems which is related to the copolymer composition. The suitability of capillary electrophoresis (CE) for following the complete preparation of the different VP-HEMA devices is shown. Moreover, CE allows simultaneous monitoring of the controlled release of GH and dissolved polymer duringin vitroexperiments. From these results, guidelines are given for the fabrication of polymeric devices containing protein as active drug as well as for the correct selection of conditions duringin vitroexperiments.

ISSN:0920-5063    

DOI:10.1163/156856200744156

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor