Biomedical subjects

D M Kim

Publications and source records attributed to D M Kim.

58 records · Page 4Linked to original sources

PubMedDate not supplied

MMA/MPEOMA copolymers as coating materials for improved blood compatibility: protein adsorption study.

Surface-induced thrombosis remains one of the main problems in the development of blood-contacting devices. When a foreign surface comes in contact with blood, the initial blood response is adsorption of blood proteins, followed by platelet adhesion and activation, leading to thrombus formation. A particularly effective polymer for the prevention of protein adsorption and platelet adhesion appears to be polyethylene oxide (PEO). In this study, water-insoluble copolymers of methyl methacrylate (MMA) and methoxy PEO monomethacrylates (MPEOMA) with different PEO molecular weights (200, 400, and 1000) and monomer composition were synthesized and characterized by gel permeation chromatography and 1H-nuclear magnetic resonance spectroscopy. The synthesized copolymers were coated on glass slides by a spin coating method to prepare PEO-rich surfaces as blood-compatible surfaces. The surface properties of the copolymers and their interaction with blood proteins (albumin, gamma-globulin, fibrinogen, and plasma proteins) were investigated by the measurement of water contact angles and by electron spectroscopy for chemical analysis, respectively. It was observed that the protein adsorption on the copolymer surfaces decreased with increasing PEO molecular weight and MPEOMA content in the copolymers. The copolymers with long PEO chains in MPEOMA (MMA/MPEO1000MA copolymers) were effective in preventing protein adsorption, even though their MPEOMA content was less than the copolymers with shorter PEO chains.

Journal Article↗

PubMedDate not supplied

Visual identification of bacterially contaminated red cells.

There have been increasing numbers of reports of transfusion-acquired Yersinia enterocolitica bacteremia (including several fatal cases). Fifteen units of whole blood were inoculated with various concentrations of Y. enterocolitica serotype 0:3 and processed into AS-3 preserved red cells (RBCs). Consistent growth of the organism was found at inoculum concentrations greater than or equal to 10 colony-forming units per mL. In all 13 units of RBCs that supported the growth of Y. enterocolitica, a darkening in color (due to hemolysis and a decrease in pO2) was observed in the bag. The attached sample segments, which were sealed from the main unit, remained sterile and did not darken. This color change was apparent in all the contaminated units by Day 35, which was 1.5 to 2 weeks after the bacteria were first detected in cultures of the blood. Hence, by comparison of the color of the segment tubing with that of the unit itself, units grossly contaminated with Y. enterocolitica can be identified prior to transfusion. Moreover, review of photographs on file at the Centers for Disease Control revealed this dramatic color change in 2 units of blood that caused transfusion-transmitted sepsis (Enterobacter agglomerans and an unidentified gram-negative bacillus, not Yersinia sp.), which demonstrated that the color change was not limited to Y. enterocolitica. This method of visual identification of contaminated units of blood could decrease the incidence of posttransfusion bacterial sepsis.

Color↗

PubMedDate not supplied

Computerized densitometric measurement system (CDMS) for the quantitative analysis of diffuse retinal nerve fiber layer atrophy.

Since observable retinal nerve fiber layer (RNFL) atrophy occures several years before irreversible glaucomatous visual field damage in glaucoma patients, quantitative assessment of the diffuse RNFL atrophy has been the goal of many research efforts. The loss of RNFL reflectance is informative sign of the diffuse RNFL atrophy, and appears in monochrome photograph of RNFL. We have, therefore, made a system by which we could measure the loss of RNFL reflectance and named it Computerized Densitometric Measurement System (CDMS). In this method, density profiles concentric with optical disc are extracted from the digitalized RNFL photograph. Density integral of superior and inferior segments in the density profile is used for the assessment of RNFL atrophy. Satisfactory results were obtained about the clinical utility of this method when the CDMS measurement was compared with the indicator of loss of visual function. Intra- and inter-operator reproducibility was also excellent.

Atrophy↗

PubMedDate not supplied

Effects of postoperative mitomycin C on glaucoma filtration surgery in rabbits treated preoperatively with antiglaucoma medications.

In a rabbit model, we evaluated the effects of topically applied postoperative mitomycin C (MMC) on the success rate of glaucoma filtration surgery in animals treated preoperatively with pilocarpine hydrochloride 4% and levobunolol hydrochloride (Betagan) for 16 weeks. Full-thickness filtration surgery was performed with a single 5-minute intraoperative exposure to a sponge soaked with 0.4 mg/mL MMC of one eye in nine rabbits in one group (group A) and to both eyes in 13 rabbits in a second group (group B). In addition, one eye of each rabbit in group B received a daily drop of 0.4 mg/mL MMC for 13 days after the operation. All of the eyes were then followed for 80 days. The intraoperatively applied MMC enhanced the success rate of the filtration surgery in the group A eyes. However, the eyes that also received postoperative drops of MMC (group B) had longer periods of reduced intraocular pressure (IOP) (P [chi-squared = 5.94] < .025), fewer bleb failures (P [chi-squared = 8.09] < .005), and more complications than the eyes that received only intraoperative MMC.

Administration, Topical↗