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Biomedical subjects

Y W Jo

Publications and source records attributed to Y W Jo.

5 recordsLinked to original sources
PubMed2001

Preparation and characterization of a composite PLGA and poly(acryloyl hydroxyethyl starch) microsphere system for protein delivery.

PURPOSE: To prepare and characterize a novel composite microsphere system based on poly(D,L-lactide-co-glycolide) (PLGA) and poly(acryloyl hydroxyethyl starch) (acHES) hydrogel for controlled protein delivery. METHODS: Model proteins, bovine serum albumin, and horseradish peroxidase were encapsulated in the acHES hydrogel, and then the protein-containing acHES hydrogel particles were fabricated in the PLGA matrix by a solvent extraction or evaporation method. The protein-loaded PLGA-acHES composite microspheres were characterized for protein loading efficiency, particle size, and in vitro protein release. Protein stability was examined by size-exclusion chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and monitoring the enzymatic activity. RESULTS: Scanning electron microscopy showed discrete PLGA microspheres containing many acHES particles. The composite microspheres were spherical and smooth in size range of 39-93 microm. The drug loading efficiency ranged from 51 to 101%. The composite microspheres showed more favorable in vitro release than conventional PLGA microspheres. The composite microspheres showed 20% less initial with a gradual sustained release compared to high burst (approximately 60%) followed by a very slow release with the conventional PLGA microspheres. The composite microspheres also stabilized encapsulated proteins from the loss of activity during the microsphere preparation and release. Proteins extracted from the composite microspheres showed good stability without protein degradation products and structural integrity changes in the size-exclusion chromatography and SDS-PAGE analyses. Horseradish peroxidase extracted from microspheres retained more than 81% enzymatic activity. CONCLUSION: The PLGA-acHES composite microsphere system could be useful for the controlled delivery of protein drugs.

Acrylic Resins↗
PubMed2001

Enhancement of bone growth by sustained delivery of recombinant human bone morphogenetic protein-2 in a polymeric matrix.

PURPOSE: The purpose of this study was to develop a polymeric sustained delivery system for recombinant human bone morphogenetic protein-2 (BMP-2) and to evaluate local bone growth induced by the sustained release of BMP-2 in an animal model. METHODS: BMP-2 was incorporated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres to obtain different release rates. Two sustained and an immediate release implants were produced by suspending the BMP-2 loaded PLGA microspheres in aqueous sodium carboxymethylcellulose (CMC), lyophilizing, and cutting the dried materials to the size of the animal bone defects. The local in vivo release at the implantation site in rat calvarial defects was determined by gamma scintigraphy using radiolabeled BMP-2. The local bone induction in the critical size of rabbit calvarial defects was evaluated six weeks post implantation. RESULTS: The immediate release implant showed about 65% initial drug release within 24 h and the remaining BMP-2 quickly exhausted from the implantation site within 7 days. The sustained release implants, showing 45-55% initial release followed by a prolonged release for 21 days, released a greater amount of BMP-2 at the implantation site and maintained higher serum BMP-2 for the longer period of time compared to the immediate release implant. Significant bone growth was observed in all BMP-2 treated defects while the defects without treatment or with BMP-2-free implant showed minimal bone healing. 75-79% of rabbit calvarial defect area was healed with newly induced bone matrix by the sustained release implants in 6 weeks as compared to 45% recovery from the immediate release implant. CONCLUSION: The sustained delivery of BMP-2 based on the biodegradable PLGA microsphere system resulted in faster and more complete bone healing in the animal model.

Animals↗
PubMed1989

Inhibition ELISA for hepatitis B surface antigen (HBsAg) using monoclonal idiotype-anti-idiotype interaction.

Monoclonal anti-idiotypic antibody (Anti-Id) to the common (a) epitope of hepatitis B surface antigen (HBsAg) were raised and used to detect serum HBsAg in an inhibition enzyme-linked immunosorbent assay (inhibition ELISA). HRP-labelled Id 8D-3-6 was reacted with Anti-Id 4-8H coated on the solid phase in the presence of HBsAg. The ability of the antigen to inhibit the binding of labelled Id 8D-3-6 to anti-Id 4-8H was determined and the results correlated well with those obtained by radioimmunoassay. This assay requires only one washing step, takes 2 h and covers the range 10 ng/ml to 1 microgram HBsAg/ml. The inhibition ELISA is a more convenient, rapid and relatively sensitive assay which can be used to measure the level of a wide range of serum HBsAg.

Animals↗