Biomedical subjects

Byung Kook Kwak

Publications and source records attributed to Byung Kook Kwak.

4 recordsLinked to original sources

PubMed2006

Preparation and magnetic resonance imaging effect of polyvinylpyrrolidone-coated iron oxide nanoparticles.

Polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles were prepared by the thermal decomposition of Fe(CO)(5) (iron pentacarbonyl) in one step. X-ray diffraction (XRD), transmission electron microscopy (TEM), electrophoretic light scattering (ELS), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) together with the variation of the molar ratio of PVP/Fe(CO)(5), solvent, and molecular weight of PVP, were used to characterize the PVP-coated iron oxide nanoparticles. Fifty to hundred nanometer-sized iron oxide nanoclusters with a spherical shape were formed in dimethylformamide (DMF), used as a solvent, and exhibited an enhanced stability in the aqueous media. Their magnetic properties were investigated by superconducting quantum interface device (SQUID). The in vitro cytotoxicity test revealed that the PVP-coated iron oxide nanoparticles exhibited excellent biocompatibility by MTT assay. Magnetic resonance imaging (MRI) effect was observed with the administration of PVP-coated iron oxide nanoparticles through the marginal vein of rabbit, resulting in improved detection of the liver lesions.

Coated Materials, Biocompatible↗

PubMed2005

Chitin-based embolic materials in the renal artery of rabbits: pathologic evaluation of an absorbable particulate agent.

PURPOSE: To prospectively evaluate the tissue reaction to and the embolic effect and absorption of chitin and chitosan microspheres and polyvinyl alcohol (PVA) in the renal artery of rabbits. MATERIALS AND METHODS: This experiment was performed in accordance with regulations on animal care and experiments. Thirty-six New Zealand white rabbits were divided into four groups according to the materials (PVA, chitin particles, and chitosan particles, and chitosan microspheres; diameter, 150-250 microm) used for embolization of the right renal artery. A rabbit from each group was sacrificed 1 and 3 days and 1, 2, 4, 8, 16, 24, and 32 weeks after embolization. Gross and microscopic pathologic findings were examined with hematoxylin-eosin, Masson trichrome, and Victoria blue staining. RESULTS: Gross pathologic findings were examined, and swelling of embolized kidneys was observed 1 and 3 days after embolization, whereas shrinkage of the embolized kidneys was consistently seen after 2 weeks, with a hard consistency and nodular surfaces being noted. At histologic analysis, chitosan microspheres filled the lumen more compactly than did other particles. With PVA, a large amount of capillary formations occurred within the embolized arteries, whereas chitin particles and chitosan microspheres showed a lower rate of capillary formation. The shape of all embolic materials remained intact until week 8, at which time the materials gradually decreased in size and number. The chitosan particles and the chitosan microspheres were absorbed around weeks 16 and 24, respectively. CONCLUSION: Chitosan microspheres have great potential as a new embolic material since they block blood vessels more compactly with a lower rate of capillary formation. This material is biocompatible, and it is absorbed 24 weeks after embolization.

Angiography↗

PubMedDate not supplied

Diethylenetriaminepentaacetic acid-gadolinium (DTPA-Gd)-conjugated polysuccinimide derivatives as magnetic resonance imaging contrast agents.

Biocompatible polysuccinimide (PSI) derivatives conjugated with diethylenetriaminepentaacetic acid gadolinium (DTPA-Gd) were prepared as magnetic resonance imaging (MRI) contrast agents. In this study, we synthesized PSI derivatives incorporating methoxy-poly(ethylene glycol) (mPEG) as hydrophilic ligand, hexadecylamine as hydrophobic ligand, and DTPA-Gd as contrast agent. PSI was synthesized by the polycondensation polymerization of aspartic acid. All the synthesized materials were characterized by proton nuclear magnetic resonance (1H NMR). Critical micellization concentrations were determined using fluorescent probes (pyrene). Micelle size and shape were measured by electro-photometer light scattering (ELS) and atomic force microscopy (AFM). The formed micelle size ranged from 100 to 300 nm. The T1-weighted MR images of the phantom prepared with PSI-mPEG-C16-(DTPA-Gd) were obtained in a 3.0 T clinical MR imager, and the conjugates showed a great potential as MRI contrast agents.

Aspartic Acid↗

PubMedDate not supplied

Fixation methods for implantable port chamber: comparative study using glue, self-stabilizing leg and suture fixations in rabbits.

OBJECTIVE: To evaluate the fixation strength and tissue reaction of the glue fixation and self-stabilizing leg fixation methods and to compare the results with those of the conventional tagging suture fixation method. MATERIALS AND METHODS: Twelve healthy rabbits were selected and three different methods of implanting the port chamber were employed on the back of each rabbit. A total of thirty six port chambers were implanted with these three different methods, viz. the glue fixation method using tissue adhesive, the self-stabilizing leg method using a self-expandable stabilizing leg, and the suture fixation method. The fixation strength and the gross and histopathologic changes of each fixation method were evaluated at three days, one week, two weeks and four weeks after port implantation. RESULTS: The glue fixation method showed a good fixation strength, which was similar to that of the tagging suture method (p = 0.3486). Five of the six ports (83%) implanted with the glue fixation method which were examined after two weeks showed cracks on the external surface, but this had no adverse effects on their function. A large amount of granulation tissue reaction was found at the bottom of the chamber (p = 0.0025). The fixation with the self-stabilizing leg showed relatively lower fixation strength (p = 0.0043), but no turning-over of the chamber occurred. The fixation strength improved with time after the first week, and minimal granulation tissue reaction was observed with this method. CONCLUSION: The glue fixation method exhibited equal fixation strength compared to the suture fixation, but showed cracking and a large amount of granulation tissue, whereas the fixation with a self-stabilizing leg showed weaker fixation strength.

Alloys↗