Biomedical subjects

Hyun Ju Choi

Publications and source records attributed to Hyun Ju Choi.

6 recordsLinked to original sources

PubMed2006

Development of quantification software using model-based segmentation of left ventricular myocardium in gated myocardial SPECT.

Gated myocardial single photon emission computed tomography (SPECT) is being used for the diagnosis of coronary artery diseases. In this study, we developed new software for the quantification of volumes and ejection fraction (EF) on the gated myocardial SPECT data using a cylindrical model. Volumes and EF by developed software were validated by comparing with those quantified by quantitative gated SPECT (QGS) software. Cylinder model for left ventricular myocardium was used to eliminate background activity and count profiles across the myocardium were fitted to the Gaussian curve to determine the endocardial and epicardial boundary. End-diastolic volume (EDV), end-systolic volume (ESV) and EF were calculated using this boundary information. Gated myocardial SPECT was performed in 83 patients. EDV, ESV and EF values estimated using present method were compared to those obtained using the commercialized software QGS, and reproducibility in the parameter estimation was assessed. EF, EDV and ESV obtained using two methods were correlated well (correlation coefficients = 0.96, 0.96 and 0.98). The correlation between the parameters repetitively estimated from the same data set by an operator was very high (correlation coefficients = 0.96, 0.99 and 0.99 for EF, EDV and ESV). On the repeated acquisition, reproducibility was also high with correlation coefficients of 0.89, 0.97 and 0.98. The present software will be useful for the development of new parameters for describing the perfusion and function of the LV.

Aged↗

PubMed2005

Isoliquiritigenin induces apoptosis by depolarizing mitochondrial membranes in prostate cancer cells.

Isoliquiritigenin (ISL), a simple chalcone derivative, 4,2',4'-trihydroxychalcone, found in licorice, shallot and bean sprouts, has been reported to have chemoprotective effects. To examine the effects of ISL on the growth of prostate cancer cells, we cultured MAT-LyLu (MLL) rat and DU145 human prostate cancer cells with various concentrations (0-20 micromol/L) of ISL. Treatment of the cells with increasing concentrations of ISL led to dose-dependent decreases in the viable cell numbers in both DU145 and MLL cells (P<.05). Hoechst 33258 dye staining of condensed nuclei and annexin V binding to surface phosphatidylserine revealed increased numbers of apoptotic cells after ISL treatment. Western blot analysis revealed that ISL increased the levels of membrane-bound Fas ligand (FasL), Fas, cleaved casapse-8, truncated Bid (tBid), Bax and Bad in DU145 cells (P<.05). Isoliquiritigenin increased the percentage of cells with depolarized mitochondrial membranes, in a concentration-dependent manner (P<.05). Isoliquiritigenin induced the release of cytochrome c and Smac/Diablo from the mitochondria into the cytoplasm (P<.05). Isoliquiritigenin dose-dependently increased the levels of cleaved caspase-9, caspase-7, caspase-3 and poly(ADP-ribose) polymerase (P<.05). The present results indicate that ISL inhibits prostate cancer cell growth by the induction of apoptosis, which is mediated through mitochondrial events, which are associated with an evident disruption of the mitochondrial membrane potential, and the release of cytochrome c and Smac/Diablo, and the activation of caspase-9.

Animals↗

PubMed2005

Micropatterning of biomolecules on glass surfaces modified with various functional groups using photoactivatable biotin.

Biomolecule patterning by photolithographic methods has considerable advantages because a large number of different biomolecules can be assembled on a spatial area by a combinatorial method and complex biomolecule patterning can be created in situ in closed environments such as microfluidic channels. Here, a photobiotin was used as the photoactivatable reagent to create patterned arrays of biomolecules. The variability of photobiotin deposition on glass substrates modified with a variety of materials having carboxyl, lysine, aldehyde, amine groups, and BSA (bovine serum albumin) was characterized by subsequent derivatization with Cy3-labeled streptavidin. The fluorescence images of the photobiotin patterned glass surfaces showed that the BSA/aldehyde-coated glass could be considered as the most appropriate substrate to immobilize photobiotin, in view of the homogeneous immobilization of biomolecules with high density in defined regions and the reduction of nonspecific binding to the surface. In streptavidin equilibrium adsorption assays, the maximum amount of streptavidin-Cy3 bound to the BSA/aldehyde-coated glass surface continued to rise with increasing streptavidin-Cy3 concentration until 12.0 microg/mL was reached and the surface then became saturated. Also, a line array of biotin-labeled single-strand probe DNAs was created on the BSA/aldehyde-coated glass by photolysis of photobiotin through a slit-type mask and biotin/streptavidin/biotin chemistry, extended to a quantitative measurement of the concentrations of target DNA. The results of target DNA analysis showed linearity over a wide range from 0.5 ng/mL to 5 microg/mL and were reproducible.

Aldehydes↗

PubMed2005

Quantitative analysis of chemotherapeutic effects in tumors using in vivo staining and correlative histology.

AIMS: To microscopically analyze the chemotherapeutic response of tumors using in vivo staining based on an annexinV-Cy5.5 probe and independently asses their apoptotic count using quantitative histological analysis. METHODS: Lewis Lung Carcinomas cells, that are sensitive (CS-LLC) and resistant (CR-LLC) to chemotherapy were implanted in nude mice and grown to tumours. Mice were treated with cyclophosphamide and injected with a Cy5.5-annexinV fluorescent probe. In vivo imaging was performed using Fluorescence Molecular Tomography. Subsequently tumours were excised and prepared for histology. The histological tumour sections were stained for apoptosis using a terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. A minimum of ten tissue sections were analyzed per tumour for apoptosis quantification by TUNEL staining and corresponding Cy5.5 distribution. RESULTS: We detected higher levels of apoptosis and corresponding higher levels of Cy5.5 fluorescence in the CS-LLC vs. the CR-LLC tumours. The cell count rate on CS-LLC sections over CR-LLC was found to be approximately 2 :1 where the corresponding area observed on Cy5.5 distribution measurements revealed a approximately 1.7 :1 ratio of CS-LLC over CR-LLC. These observations are consistent with the higher apoptotic index expected from the CS-LLC cell line. CONCLUSIONS: Quantitative analysis of histological slices revealed higher fluorescence and higher apoptotic count in the CS-LLC tumour images compared to the CR-LLC tumour images. These observations demonstrate that the annexinV-Cy5.5 probe sensed the chemotherapeutic effect of cyclophospamide and further confirmed in vivo FMT measurements.

Animals↗

PubMed2003

The polysaccharide fraction AIP1 from Artemisia iwayomogi suppresses apoptotic death of the mouse spleen cells in culture.

A polysaccharide fraction, AIP1, purified from Artemisia iwayomogi was shown to have immunomodulating and anti-tumor activities in mice. In order to determine how the AIP1 fraction exhibits the immunomodulating activity, the effect of the fraction on the apoptosis of mouse spleen cells was investigated. Treatment of the mouse spleen cells with the AIP1 fraction resulted in the suppression of apoptotic death and an extension of cell survival in culture, indicating that the fraction might modulate the death of spleen cells. Treatment of the mice with the AIP1 fraction in vivo also resulted in less apoptosis of the spleen cells, which indicates the physiological relevance of the anti-apoptosis effect of the fraction in vitro. A mouse gene array was used to determine the profile of the gene expression change showing a pattern of up- and down-regulated genes by the AIP1 treatment. This study provides preliminary information regarding the immunomodulatory mechanism of the AIP1 fraction.

Animals↗

PubMed2003

An oligosaccharide fraction from Korean mugwort herb suppresses death of the mouse thymocytes in culture by down-regulating the Fas death receptor gene.

Korean mugwort herb is a preparation of dried leaves from Artemisia species and has been used as a traditional medicine in Asia. An oligosaccharide fraction, AVF3, purified from the preparation promoted survival of the mouse thymocytes in culture. A mouse gene array study suggests that the AVF3 may modulate Fas/FasL dependent apoptotic cell death and thus has influence on the survival of the thymocytes in culture. RT-PCR analysis confirmed the down-regulation of the Fas gene by the AVF3 treatment, supporting that the AVF3 modulated thymocyte death by suppressing the Fas gene expression.

Animals↗