Biomedical subjects

Sukyoung Kim

Publications and source records attributed to Sukyoung Kim.

7 recordsLinked to original sources

PubMed2006

Preparation and characterization of anodized titanium surfaces and their effect on osteoblast responses.

In this study, titanium (Ti) surface was modified by anodizing with a mixture of beta-glycerophosphate sodium and calcium (Ca) acetate, and the anodized surfaces were characterized by scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. In vitro osteoblast response to anodized oxide was also evaluated. The anodic oxide produced was observed to have interconnected pores (0.5-2 microm in diameter) and intermediate roughness (0.60-1.00 microm). In addition, anodic oxide was observed to have amorphous and anatase oxide. Calcium and phosphorus ions were deposited on the Ti oxide during anodization. Osteoblast differentiation, as indicated by alkaline phosphatase production, was enhanced on anodized surfaces. It was thus concluded from this study that Ca phosphate can be deposited on Ti surfaces by anodization. It was also concluded that the phenotypic expression of osteoblast was enhanced by the presence of Ca phosphate and higher roughness on anodized Ti surfaces.

Acetates↗

PubMed2005

Morphology and metabolism of Ba-alginate encapsulated hepatocytes with galactosylated poly(allyl amine) and poly(vinyl alcohol) as extracellular matrices.

Lactobionic acid, bearing a beta -galactose group, was coupled with poly(allyl amine) to provide synthetic extracellular matrices together with poly(vinyl alcohol) (PVA). The hepatocytes were encapsulated in Ba-alginate capsules with galactosylated poly(allyl amine) (GA) and PVA as extracellular matrices. From microscopic observation, it was revealed that the microcapsule prepared has a highly porous structure with interconnected pores and pore sizes ranging between 50-150 nm on both the surface and the cross-section. It was found, from the permeability experiment of microcapsules using FITC-dextrans with different molecular weights, that the capsule has a molecular weight cut off (MWCO) of 120 kDa, showing the potential that it can function as an immunoprotecting wall. The hepatocytes, cultured with GA and PVA in the core of the microcapsule, rapidly aggregated within a day, thus resulting in good metabolic functions such as albumin synthesis and ammonia removal.

Albumins↗

PubMed2005

A poly(lactic acid)/calcium metaphosphate composite for bone tissue engineering.

A new method to prepare PLA/CMP (poly-L-lactide/calcium metaphosphate) composite scaffolds was developed for effective bone tissue engineering. This novel sintering method is composed of pressing the mixture of PLA, CMP, and salt particles at 150 MPa for 3 min followed by heat treatment at 210 degrees C for 30 min. The scaffolds had a homogeneously interconnected porous structure without a skin layer, and they exhibited a narrower pore size distribution and higher mechanical strength in comparison with scaffolds made by a solvent casting method. The scaffolds were seeded by osteoblasts and cultured in vitro or implanted into nude mice subcutaneously for up to 5 weeks. The number of cells attached to and proliferated on the scaffolds at both in vitro and in vivo was in the order of; PLA by novel sintering < PLA/CMP by solvent casting < PLA/CMP by novel sintering. In addition, the alkaline phosphatase activity of and calcium deposition in the scaffolds explanted from mice were enhanced significantly for the scaffolds by novel sintering compared to them by solvent casting. The in vitro results agreed well with the in vivo data. Such a superior characteristic of the novel sintering method should have resulted from the fact that the CMP particles could contact directly with cells/tissues to stimulate the cell proliferation and osteogenic differentiation, while the CMP particles would be coated by polymers and hindered to interact with cells/tissues in the case of a solvent casting method. As the novel sintering method does not use any solvents it offers another advantage to avoid problems associated with solvent residue.

Animals↗

PubMed2004

Wear of retrieved UHMWPE hip liners.

After the gamma-irradiation sterilization, the most widely used orthopaedic grade polymer bearing liner material for the total joint replacement, ultra-high molecular weight polyethylene (UHMWPE), degrades through the progressive in vivo oxidation. The oxidative degradation makes UHMWPE brittle and leads to reduction of its mechanical properties. In this study, the effect of the in vivo post-irradiation ageing time on the wear of UHMWPE was investigated. Twelve retrieved polyethylene hip liners implanted for 3-16 years and then stored in the air for 1.5-8 years were used. Two types of the pin-on-disk wear testing were conducted. The uni-directional repeat pass rotating and the linear reciprocating wear testing were done with stainless steel disks against stationary polyethylene pins under 4MPa at 1Hz with bovine serum lubrication. Wear of the retrieved polyethylene hip liners does not have significant correlation with the in vivo or total ageing time. The linear reciprocal sliding motion generated a more pronounced wear than the uni-directional repeat pass sliding motion. This indicates that the kinematic motion significantly affects the wear of aged UHMWPE, having a brittle, white band region.

Arthroplasty, Replacement, Hip↗

PubMed2004

Cellular biocompatibility and stimulatory effects of calcium metaphosphate on osteoblastic differentiation of human bone marrow-derived stromal cells.

In the present study, the in vitro biocompatibility of calcium metaphosphate (CMP) with human bone marrow stromal cells (HBMSCs) and its effect on osteoblastic differentiation have been investigated. Powder and disk forms of CMP do not exert a cytotoxic effect on the HBMSCs undergoing osteoblastic differentiation. In addition, the HBMSCs adhere to the surface of the CMP disk as successfully as to the culture plate or hydroxyapatite (HA) disk. The HBMSCs adhered to either the HA or CMP disk display an undistinguishable actin arrangement and cellular phenotypes, indicating that the CMP does not disrupt normal cellular responses. An analysis of the differentiation of the HBMSCs cultured on culture plate, the HA and the CMP disk shows that three matrices are capable of supporting osteoblastic differentiation of the HBMSCs as accessed by alkaline phosphatase (ALP) staining. Further molecular analysis of osteoblastic differentiation of HBMSCs reveals that the CMP disk has a better ability than the HA disk to induce an expression of osteoblast-related genes, including ALP, osteoprotegerin (OPG), a decoy receptor for RANK ligand, and osteopontin (OPN), a non-collagenous bone matrix protein. The results demonstrate that, in addition to favorable biocompatibility, the CMP can stimulate osteoblastic differentiation of the HBMSCs in vitro.

Biocompatible Materials↗

PubMed2002

Surface characteristics and structure of anodic oxide films containing Ca and P on a titanium implant material.

An anodic oxide film that formed on titanium with a mixture of beta-glycerophosphate sodium (beta-GP) and calcium acetate was investigated. The anodic oxide had interconnected pores (ca. 1-2 microm in diameter) and intermediate roughness (0.60-1.50 microm). In addition, it contained a mixture of amorphous, anatase, and rutile oxides. With an increase in the anodizing voltage and/or concentration of calcium incorporated into the oxide, the degree of oxide crystallinity increased. However, with an increase in the concentration of beta-GP, the degree of oxide crystallinity decreased. It was concluded that the surface roughness, oxide crystallinity, and surface composition of the anodic oxide were dependent on the voltage, current density, and concentration of the electrolyte. It was also concluded that the anodized surface could be optimized for maximum osseointegration.

Calcium↗

PubMed2002

Hydroxyapatite and calcium phosphate coatings on aluminium oxide orbital implants.

BACKGROUND: Hydroxyapatite and calcium phosphate have been used as bone graft substitutes as they facilitate and promote tissue ingrowth. We carried out a study to examine uncoated and coated aluminium oxide (alumina) spherical orbital implants and assess whether the coatings influence fibrovascular ingrowth. METHODS: The aluminium oxide spheres (three coated with hydroxyapatite, three coated with calcium metaphosphate and three uncoated) were manufactured at the School of Materials Engineering, Yeungnam University, Kyongsan, Kyongbuk, Korea. The implants were examined macroscopically and with scanning electron microscopy and were analysed chemically by means of x-ray powder diffraction and x-ray fluorescence spectrophotometry. Implantation of three hydroxyapatite-coated, three calcium metaphosphate-coated and three uncoated aluminium oxide spheres was done in nine adult male New Zealand albino rabbits. Implant vascularization was evaluated at 4, 8 and 12 weeks by means of histopathological sectioning. RESULTS: All three types of implant had multiple interconnected pores. The coatings increased the size of the trabeculae from 150 microm to 300 microm. As a result, the pores appeared slightly smaller but still ranged in size from 300 microm to 750 microm, compared to 400 microm to 800 microm in the uncoated implants. The coatings also increased the weight of the implants slightly. The implants were all strong mechanically. They were made up primarily of aluminium oxide. The coated implants contained significant amounts of calcium oxide (a contaminant). There was no clinical difference in the socket response between the three groups. Histopathologically, fibrovascularization occurred uniformly throughout each implant at 4, 8 and 12 weeks after implantation. INTERPRETATION: The hydroxyapatite and calcium metaphosphate coatings did not appear to facilitate or inhibit fibrovascular ingrowth at 4, 8 and 12 weeks. Longer-term studies are need to determine whether the coatings play a role in long-term acceptance and retention of the implants.

Aluminum Oxide↗