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Biomedical subjects

In Kyu Park

Publications and source records attributed to In Kyu Park.

7 recordsLinked to original sources
PubMed2006

Complete stable remission after extended transsternal thymectomy in myasthenia gravis.

OBJECTIVE: This study sought to determine the efficacy and prognostic factors of extended transsternal thymectomy as a treatment for myasthenia gravis (MG). METHODS: Medical records of 147 patients who underwent extended transsternal thymectomy for MG from January 1991 to December 2002 were reviewed retrospectively. The complete stable remission (CSR) rate and prognostic factors for CSR were assessed in 106 female and 41 male patients. RESULTS: The median age was 35 years (range 11-75 years). Ninety-eight patients had non-thymomatous MG and 49 patients had thymomatous MG. The median follow-up time was 89.7 months (range 12-167 months). Both non-thymomatous MG and thymomatous MG exhibited significant differences in population characteristics and CSR rates (29.6% vs 13.3% at 5 years, 45.2% vs 27.7% at 10 years, p = 0.022). Steroid therapy (hazard ratio: 0.234, p = 0.003) was a poor prognostic factor, while early onset (hazard ratio: 3.519, p = 0.048) was a good prognostic factor for CSR in non-thymomatous MG. In contrast, steroid therapy (hazard ratio: 0.061, p = 0.034) was poor prognostic factor for thymomatous MG. CONCLUSIONS: Extended transsternal thymectomy is a good treatment tool to achieve CSR in MG. Thymomatous MG and non-thymomatous MG were significantly different in patient characteristics and prognosis. Prognostic factors were steroid therapy and age of onset in non-thymomatous MG, and steroid therapy in thymomatous MG.

Adolescent↗
PubMed2006

[Glutathione S-transferases (GSTM1, GSTT1 and GSTP1) and N-acetyltransferase 2 polymorphisms and the risk of gastric cancer].

OBJECTIVES: Polymorphisms of genes from glutathione S-transferases (GSTs) and N-acetyltransferase 2 (NAT2) have been associated with increased susceptibility to various cancers. Previous results showed that East Asians such as Koreans, Japanese and Chinese have a much higher frequency of the GSTM1 and GSTT1 null genotypes and NAT2 rapid acetylator type. Therefore, we investigated the association between the polymorphic types of GSTs (GSTM1, GSTT1, GSTP1) and NAT2 and the incidence of gastric cancer which is one of the most prevalent cancers among the East Asians. METHODS: It was performed in a case-control study consisting of 238 healthy subjects and 108 cancer patients (54 distal and 54 proximal carcinomas). We also evaluated the association between GSTs and NAT2 and the risk factors for gastric cancer such as alcohol consumption, smoking, H. pylori infection, family history of gastric cancer, and tumor location. RESULTS: In our study, the percentage of cases whose hometown was rural was higher than those of controls (odds ratio (OR) = 2.88; 95% CI = 1.72-4.76), and the frequency of the lower socio-economic status increased significantly in patients (OR = 2.53; 95% Cl = 1.59-4.02). There was no significant difference in the GST polymorphic types between the cases and controls. However, NAT2 rapid or intermediate acetylator types were frequently detected in the cases with family history of gastric cancer (OR = 1.92; 95% CI = 1.79-26.0). CONCLUSIONS: These results suggest that the hometown and socio-economic status are important environmental factors for gastric carcinogenesis, and NAT2 polymorphic types could be associated with familial gastric carcinoma.

Aged↗
PubMed2005

Galactosylated polyethylenimine-graft-poly(vinyl pyrrolidone) as a hepatocyte-targeting gene carrier.

Polyethylenimine (PEI) has been used for the gene delivery system in vitro and in vivo since it has high transfection efficiency owing to proton buffer capacity. However, the use of PEI for gene delivery is limited due to cytotoxicity, non-specificity and unnecessary interaction with serum components. To overcome cytotoxicity and non-specificity, PEI was coupled with poly(vinyl pyrrolidone) (PVP) as the hydrophilic group to reduce cytotoxicity and lactose bearing galactose group for hepatocyte targeting. The galactosylated-PEI-graft-PVP (GPP) was complexed with DNA, and GPP/DNA complexes were characterized. GPP showed good DNA binding ability, high protection of DNA from nuclease attack. The sizes of DNA complexes show tendency to decrease with an increase of charge ratio and had a minimum value around 59 nm at the charge ratio of 40 for the GPP-1/DNA complex (PVP content: 4.1 mol%). The GPP showed low cytotoxicity. And GPP/DNA complexes were mediated by asialoglycoprotein receptors (ASGP-R)-mediated endocytosis. Also, the transfection efficiency of GPP-1/DNA complex at charge ratio of 40 in the HepG2 was higher than that of PEI/DNA one.

Cell Line, Tumor↗
PubMed2004

Aerosol delivery of glucosylated polyethylenimine/phosphatase and tensin homologue deleted on chromosome 10 complex suppresses Akt downstream pathways in the lung of K-ras null mice.

Difficulties in achieving long-term survival of lung cancer patients treated with conventional therapies suggest that novel approaches are required. Although several genes have been investigated for antitumor activities using gene delivery, problems surrounding the methods used such as efficiency, specificity, and toxicity hinder its application as an effective therapy. This has lead to the re-emergence of aerosol gene delivery as a noninvasive approach to lung cancer therapy. In this study, glucosylated conjugated polyethylenimine (glucosylated PEI) was used as carrier. After confirming the efficiency of glucosylated PEI carriers in lungs, the potential effects of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene on Akt downstream pathways were investigated. Aerosol containing glucosylated PEI and recombinant plasmid pcDNA3.0-PTEN complex was delivered into K-ras null lung cancer model mice through a nose-only inhalation system. Investigation of proteins in the phosphatidylinositol 3'-kinase/Akt signaling pathway in PTEN-delivered mouse lung revealed that the PTEN protein was highly expressed, whereas the protein levels of PDK1, total Akt1, phospho-(Thr-308)-Akt, phospho-(Ser-2448)-mTOR, p70S6K, and 4E-BP1 were decreased to varying degrees. Additionally, the kinase activities of both Akt and mTOR were suppressed. Finally, apoptosis was detected in PTEN-delivered mouse lung by terminal deoxynucleotidyltransferase-mediated nick end labeling assay, suggesting that our aerosol PTEN delivery is capable of functionally altering cell phenotype in vivo. In summary, Western blot analysis, kinase assays, immunohistochemistry, and terminal deoxynucleotidyltransferase-mediated nick end labeling assays suggest that our aerosol gene delivery technique is compatible with in vivo gene delivery and can be applied as a noninvasive gene therapy.

Aerosols↗
PubMed2004

Galactosylated chitosan/DNA nanoparticles prepared using water-soluble chitosan as a gene carrier.

Water-soluble chitosan (WSC) was used to increase the stability of chitosan in water and decrease the cytotoxicity induced by acetic acid. Lactobionic acid (LA) bearing galactose group was coupled with WSC for hepatocytes specificity. The composition of galactose in galactosylated chitosan (GC) was determined by NMR spectroscopy. The GC was complexed with plasmid DNA in various GC/DNA (N/P) charge ratios and the resulting complex was characterized by dynamic light scattering, gel retardation, and turbidity to determine the particle sizes, complex formation, and complex stability, respectively. Cytotoxicity and transfection efficiency of GC were also studied in cultured HepG2 human hepatoblastoma cell line and HeLa human cervix epithelial carcinoma cells. The complete GC/DNA complex was formed at the charge ratio of 5 and the GC/DNA complex to DNase I resistance was obtained. Particle sizes decreased with increasing charge ratio of GC to DNA and had a minimum value around 120 nm at the charge ratio of 5. And no significant difference in particle sizes from the charge ratio of 5-20 was found. The suspension of GC/DNA complexes exhibited no significant change in turbidity at the charge ratios of 10, indicating the complete shielding of DNA charge. Cytotoxicity study showed that GC prepared by the water-soluble chitosan had no cytotoxic effects on cells. And transfection efficiency into HepG2, which has asialoglycoprotein receptors (ASGP-R), was higher than that into HeLa without ASGP-R.

Absorption↗
PubMed2003

A novel degradable polycaprolactone networks for tissue engineering.

Polycaprolactone (PCL) macromer was obtained by the reaction of PCL diol with acryloyl chloride and confirmed using Fourier transform infrared and nuclear magnetic resonance spectrometer. Novel degradable PCL networks were prepared through photopolymerization of the PCL macromer. Thermal, mechanical, and morphological characteristics as well as degradability and biocompatibility of the PCL networks were investigated. Differential scanning calorimetry showed that the melting temperature and the calculated weight average crystallinity of PCL networks were decreased with a decrease of molecular weight of PCL diols due to the increased crosslinking density. Thermal stability of PCL networks was higher than that of PCL diols. PCL networks showed faster degradation, and higher compressive modulus and compressive recovery ratios than those of PCL itself because of their low crystallinity and the modification of terminal groups. The porosity of the PCL networks can be controlled by the amounts and size of porogen used. MG-63 osteoblast cell was attached and proliferated on PCL networks. PCL networks therefore may have considerable potential as scaffold for tissue engineering.

Biocompatible Materials↗