PubMed Health⌕ Search

Biomedical subjects

Dong Sik Kim

Publications and source records attributed to Dong Sik Kim.

6 recordsLinked to original sources
PubMed2006

Efficacy of therapeutic angiogenesis by intramyocardial injection of pCK-VEGF165 in pigs.

BACKGROUND: Intramyocardial injection of vascular endothelial growth factor (VEGF) plasmid DNA was studied to demonstrate improvement of regional myocardial function. METHODS: Twenty-one pigs that had undergone ligation of the left anterior descending coronary artery were randomly allocated to one of two treatments: intramyocardial injection of pCK-VEGF165 (VEGF group) or pCK-Null (control group) into the ischemic border zone. Electrocardiogram-gated single-photon emission computed tomography was performed 30 and 60 days after the coronary ligation. Segmental variables of perfusion and function were automatically quantified using a 20-segment model. In the segmental analysis, 119 segments were selected for analysis (71 segments in the VEGF group; 48 segments in the control group). Histologic analysis was also performed in the myocardial tissue of the ischemic border zone. RESULTS: At day 30, there were no significant differences in segmental perfusion, wall thickening, and wall motion between the two groups. In the VEGF group, all variables of perfusion, wall thickening, and wall motion were significantly improved at day 60 compared with those at day 30 (p < 0.05), while there were no differences in the control group. At day 60, perfusion (p = 0.018), wall motion (p = 0.004), and wall thickening (p = 0.068) of the VEGF group were improved compared with those of the control group. Histologic analysis showed that microcapillary density was significantly higher in the VEGF group than the control group (p < 0.001). CONCLUSIONS: Intramyocardial injection of pCK-VEGF165 significantly augmented neoangiogenesis in the ischemic area and improved regional myocardial function as well as myocardial perfusion.

Animals↗
PubMed2005

Individualization of single-walled carbon nanotubes: is the solvent important?

The influence of different solvents on the individualization of single-walled carbon nanotubes (SWNTs) was investigated by several methods. A stable solution of individual SWNTs in o-dichlorobenzene was obtained by a combination of ultrasonication and ultracentrifugation. Atomic force microscopy height analysis confirmed that the final supernatant solution contained 85 % of individual tubes with a diameter equal to or less than 1.5 nm, which is consistent with the average diameter of arc-discharge tubes. Both the solvent and the ultracentrifugation speed are important parameters in determining the final degree of individualized SWNTs. Notably, the SWNTs were stable in o-dichlorobenzene for more than eight months. This technique for obtaining highly individualized SWNTs in an organic solvent is expected to have great potential in many applications, such as functional materials and nanoelectronics.

Acetamides↗
PubMed2005

Regression-based prediction for blocking artifact reduction in JPEG-compressed images.

In order to reduce the blocking artifact in the Joint Photographic Experts Group (JPEG)-compressed images, a new noniterative postprocessing algorithm is proposed. The algorithm consists of a two-step operation: low-pass filtering and then predicting. Predicting the original image from the low-pass filtered image is performed by using the predictors, which are constructed based on a broken line regression model. The constructed predictor is a generalized version of the projector onto the quantization constraint set, or the narrow quantization constraint set. We employed different predictors depending on the frequency components in the discrete cosine transform (DCT) domain since each component has different statistical properties. Further, by using a simple classifier, we adaptively applied the predictors depending on the local variance of the DCT block. This adaptation enables an appropriate blurring depending on the smooth or detail region, and shows improved performance in terms of the average distortion and the perceptual view. For the major-edge DCT blocks, which usually suffer from the ringing artifact, the quality of fit to the regression model is usually not good. By making a modification of the regression model for such DCT blocks, we can also obtain a good perceptual view. The proposed algorithm does not employ any sophisticated edge-oriented classifiers and nonlinear filters. Compared to the previously proposed algorithms, the proposed algorithm provides comparable or better results with less computational complexity.

Algorithms↗
PubMed2004

Agonist-induced internalization of leukotriene B(4) receptor 1 requires G-protein-coupled receptor kinase 2 but not arrestins.

The leukotriene B(4) (LTB(4)) receptor (BLT1) becomes desensitized upon repeated agonist stimulation. Little is known, however, about BLT1 internalization, which follows desensitization in most G-protein-coupled receptors (GPCR). In the current study, transiently expressed BLT1 readily internalized, after LTB(4) stimulation, in RBL-2H3 cells that express high levels of endogenous GPCR kinase 2 (GRK2) but did not in COS-7 or human embryonic kidney (HEK) 293 cells, which do not overexpress GRK. The internalization of BLT1 could be blocked in RBL-2H3 cells by coexpressing dominant-negative (DN) GRK2 K220R and could be promoted in HEK293 cells by coexpressing wild-type (WT) GRK2. Coexpression of WT or DN nonvisual arrestins had no effect on BLT1 internalization. Moreover, upon stimulation with LTB(4), BLT1 did not induce arrestin-green fluorescence protein redistribution in either cell type, even in the presence of overexpressed GRK2. Coimmunoprecipitation experiments confirmed that BLT1 could associate with GRK2 but not with arrestins. A C-tail-truncated mutant of BLT1 lost the capacity to internalize and associate with GRK2 upon exposure to LTB(4), suggesting that the C-tail was required for receptor internalization and association with GRK2. Taken together, our results indicate that the C terminus of BLT1 plays a pivotal role in receptor internalization and GRK2 association. Moreover, ligand-induced BLT1 internalization is dependent on GRK2 but independent of arrestins. This may allow differential, cell-type-specific signaling in response to LTB(4), depending on GRK expression levels.

Animals↗
PubMedDate not supplied

Clinical analysis of right anterior segmentectomy for hepatic malignancy.

BACKGROUND/AIMS: Combined resection of segments 5 and 8, or right anterior segmentectomy, is one of the most difficult hepatic resections because of the danger of bleeding from the two major hepatic veins, the middle and right hepatic veins, during hepatectomy. We describe here the operative procedure and clinical analysis of right anterior segmentectomy in 35 patients with hepatic malignancy. METHODOLOGY: Between March 1993 and December 2004, 35 patients underwent right anterior segmentectomy for hepatic malignancy. The technique used was based on the extraglissonian approach and parenchymal Kelly crushing, during which the two major hepatic veins were almost fully exposed. RESULTS: Thirty-three patients had hepatocellular carcinoma, one had peripheral cholangiocellular carcinoma, and one had primary hepatic sarcoma. The mean operation time was 331 +/- 73 minutes and the mean transfusion of packed RBC was 1.09 +/- 1.57 pints. There was one in-hospital death as a result of sepsis and hepatic failure. The cumulative 1-, 2- and 5-year survival rates were 94%, 72% and 62%, respectively. CONCLUSIONS: For surgeons who accurately know the anatomy of the liver, this procedure is safe and suitable in selected patients with hepatic malignancies and may increase the survival rate.

Carcinoma, Hepatocellular↗