Biomedical subjects

M R Bet

Publications and source records attributed to M R Bet.

3 recordsLinked to original sources

PubMed2003

Cell adhesion and cytotoxicity studies over polyanionic collagen surfaces with variable negative charge and wettability.

This work describes the cytotoxicity, and the cell adhesion behavior of K562 cell line from human erythroleukemia transfected with the DNA for the alpha(2)beta(1) integrin over type-I collagen matrices with variable degree of carboxyl group and wettability. The results showed that type-I collagen materials with variable degree of carboxyl group prepared by selective hydrolysis of carboxyamide side chains of Asn and Gln residues present in the protein, independently from the extent of side chain hydrolysis, was characterized by preserved triple helix structure for materials with a carboxyl group content up to 87 +/- 17. Imbibition and wettability increased linearly with increasing carboxyl group content from 46 +/- 12 to 87 +/- 17, and no signs of cytotoxicity were detected. Nevertheless, in comparison to native collagen, K562 cell adhesion to PACMs was significantly improved by factors ranging from 1.60 to 1.47x, with the reduction in cell adhesion observed with increasing carboxyl content attributed to a balance between the inhibition of increasing negative charge and the stimulation by increased wettability. On the other hand, the overall improvement of K562 cell adhesion to polyanionic collagen was attributed to the introduction of new distinct motifs described as the minimal active recognition sequence for alpha(2)beta(1) integrins binding with type-I collagen produced as a result of Asn-Gly Glu-Ala alpha2(I)294-297, and Gly Gln-Arg-Gly Val-Val carboxyamide side chains hydrolysis.

Animals↗

PubMed2001

Characterization of polyanionic collagen prepared by selective hydrolysis of asparagine and glutamine carboxyamide side chains.

Acellular polyanionic collagen materials intended for biomaterial and tissue engineering uses were prepared by the selective and controlled hydrolysis of carboxyamides from asparagine and glutamine residues of type I collagen present in pericardium, tendon, and intestinal submucosa, all from bovine origin. The increase in carboxyl groups was from 26 +/- 14 (12 h of hydrolysis) to 134 +/- 12 (144 h of hydrolysis). Although collagen triple helix structure of polyanionic materials was preserved in all cases, a decrease in thermal stability and a gradual loss in the ability of collagen molecules to form fibrils were detected with increasing carboxyl content, probably as a result of changes in the pattern of electrostatic interaction. The resulting materials were basically acellular polyanionic collagen matrixes associated with an elastin content dependent on the time of hydrolysis. The results showed that the procedure described in this work may be a useful process for preparation of collagen biomaterials with variable physicochemical properties and macromolecular arrangement with respect to fibril formation and with potential use in tissue engineering.

Amides↗

PubMed1998

The controlled release of antibiotic by hydroxyapatite: anionic collagen composites.

Major problems with the treatment of osteomyelitis are associated with poor antibiotic distribution at the site of infection due to limited blood circulation to the skeletal tissue. Improved treatment procedures have been used in drug delivery systems that include bioceramics and natural and synthetic polymers. This work reports the development of anionic collagen:hydroxyapatite composite paste for sustained antibiotic release. Antibiotic release by the composite was characterized by two steps. In the first, 15.0+/-4.9% was released in the first 5 h (n = 53) by a normal Fick diffusion mechanism. In the second step, only 16.8+/-2.2% was released after 7 days. In conclusion, hydroxyapatite:anionic collagen composite can be an efficient support for sustained antibiotic release in the treatment of osteomyelitis because most of the antibiotic release may be associated with composite bioresorption, thus permitting antibiotic release throughout the healing process. Hydroxyapatite:anionic collagen paste showed good biocompatibility associated with bone tissue growth with material still being observed after 60 days from the time of implants.

Animals↗