Biomedical subjects

J U Park

Publications and source records attributed to J U Park.

7 recordsLinked to original sources

PubMed2002

Three-dimensional evaluation of positional change of the condyle after mandibular setback by means of bilateral sagittal split ramus osteotomy.

OBJECTIVE: The aim of this study was to evaluate condylar displacement in 3 dimensions by means of computed tomography after mandibular setback by sagittal split ramus osteotomy with rigid fixation and to compare these results with those from patients with mandibular advancement. STUDY DESIGN: Thirty Korean subjects with skeletal class III malocclusion who had undergone mandibular setback by sagittal split ramus osteotomy had computed tomographs taken. Tomographs were taken to evaluate the temporomandibular joint 1 month before and approximately 1 month after surgery. The position and angulation of the condyle were measured on axial or sagittal views. These measurements were analyzed to determine any correlations between the amount of mandibular movement and condylar displacement. RESULTS: The results of this study show that the condyle tends to move inferiorly and rotate inward on the axial view and backward on the sagittal view by a statistically significant amount. CONCLUSION: The positional change of the condyle after sagittal split ramus osteotomy was not correlated with the amount of the setback.

Adolescent↗

PubMed2001

Classification of Angle Class III malocclusion and its treatment modalities.

To obtain the best results in the treatment of patients with Angle Class III malocclusion, the etiologies of the malocclusion should first be clarified, and then an appropriate treatment modality should be decided. Angle Class III malocclusions in 120 subjects who had orthognathic surgery were analyzed with cephalometrics and facial photos and classified into 3 categories based on the abnormalities of the maxilla. Type A is true mandibular prognathism, which means that the maxilla is normal but the mandible is overgrown. Type B is characteristic of the overgrown maxilla and mandible with anterior crossbite. Type C indicates a hypoplastic maxilla with anterior crossbite. Treatment modalities should be differentially decided according to this new classification of Angle Class III malocclusions.

Adolescent↗

PubMed2000

Identification of a Salmonella typhimurium genomic region involved in invasion of HeLa and Henle-407 epithelial cells.

To identify the invasion determinant, a cosmid library was constructed by cloning a genomic library of Salmonella typhimurium 82/6915 into a cosmid vector, pLA2917. A genomic region involved in invasion of cultured HeLa and Henle-407 cells was subcloned into plasmid pGEM-7Z. E. coli strain DH1 carrying pSV6235 consisting of a S. typhimurium 4.6 kb genomic region in pGEM-7Z showed invasion of cultured HeLa and Henle-407 cells. Nested sequential deletions were introduced into the 4.6 kb genomic region of pSV6235. The E. coli recombinants which contained less than 1.5 kb deletions from the 5' end (SmaI site) of the genomic region invaded the cells as effectively as DH1 (pSV6235). The invasion of the recombinants carrying over 2.0 kb deletions from the end of pSV6235 was significantly inactivated compared to DH1 (pSV6235). Restriction enzyme analysis showed that the 3.1 kb fragment from the 3' end of the 4.6 kb genomic region was distinguished from the Salmonella pathogenicity I genes of S. typhimurium such as the inv, spa, and hil regions showing invasion of the cultured eukaryotic cells.

Cell Line↗

PubMed1999

Preparation of dendritic graft copolymer consisting of poly-(L-lysine) and arabinogalactan as a hepatocyte specific DNA carrier.

The dendriTIc graft copolymers (PAX) consisting of a poly(L-lysine) (PLL) main chain and grafts of arabinogalactan (AG) were prepared as a liver cell-specific DNA carrier. The copolymers were successfully prepared by reductive amination reaction between a reductive end of AG and epsilon-amino groups of PLL using NaBH3CN as a catalyst. The fractionation of a low molecular weight fraction (Mn = 25 kDa) from a crude AG (Mn = 33 kDa) was essential for the reaction to proceed. The resulting copolymers were isolated by ultrafiltration from unreacted AG and characterized by 1H NMR and gel permeation chromatography equipped with a multiangle laser light scattering detector (GPC-MALLS). The binding and internalization of DNA to hepatoma cells, HepG2, were considerably enhanced by complexing DNA with PAX copolymers. The interactions between PAX/DNA complexes and HepG2 cells were thoroughly inhibited in the presence of a competitor to asialoglycoprotein receptors (ASGP-R), indicating high specificity of the complex to ASGP-R. Furthermore, the PAX copolymers allowed the expression of the reporter gene. Our results reveal that the PAX copolymers may provide a new research tool for cell-specific gene delivery and eventually enhance gene-therapy technology.

Animals↗

PubMed1997

Simple preparation of nanoparticles coated with carbohydrate-carrying polymers.

Nanoparticles bearing carbohydrate chains on the surface can be prepared by the simple diafiltration method. The nanoparticles prepared by the present method displayed high yield, no-aggregation formation, small size, narrow size distribution, and one-step procedure. Also, the high density carbohydrate chains on the particles can be recognized by liver cells.

Animals↗

PubMed1997

Molecular analysis of the genes mediating Salmonella invasion.

To identify invasion determinants, a genomic library of Salmonella typhimurium was cloned into a cosmid vector, pLA2917. A clone, pSI623 which was invasive for HEp-2 and Henle-407 epithelial cells, was subcloned into a plasmid vector, pGEM-7Z to define the invasion genes. The subclone, pSV6235 containing a 4.5 kbp fragment of the Salmonella genomic region, was highly invasive for HEp-2 and Henle-407 cells, compared with other subclones whose Salmonella genomic regions are 7.4, 6.3, 5.5 and 1.4 kbp, respectively. This study reflects that the invasion efficiency of the host strain, Escherichia coli to HEp-2 and Henle-407 cell lines was significantly increased by the introduction of the genomic region of the virulent S. typhimurium. Restriction enzyme analysis showed that there was a single PstI site on the 27 kbp of Salmonella genomic region of pSI623, and no PstI site was found on the 4.5 kbp of genomic region of pSV6235. This finding suggests that the invasion related genes different from the inv and spa gene clusters which were identified in S. typhimurium, may exist in genomic DNA of S. typhimurium.

Cell Line↗

PubMedDate not supplied

Comb-type copolymers for controlled DNA delivery.

Various comb-type copolymer containing a polycation as a main chain was design to construct delivery systems of DNAs. The comb-type copolymers having cell-specific polysaccharides were proved to be useful to deliver DNA to the target cells in vivo. Of interest, the copolymers with abundant side chains of hydrophilic polymers are capable of stabilizing DNA triplex. Further, injectable nanoparticles for controlled releases of DNAs were fabricated from the copolymer and a biodegradable polymer.

Biocompatible Materials↗