• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.311-313
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• 2003

A thermal vapor deposition method for crystallization of insoluble analysis with matrix is established as a new sample preparation method for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A mixture of mono, bis and tris(p-ethyl benzylidene) sorbitols was incorporated into microcrystals of ferulic acid, which was confirmed by confocal micrographs. Molecular masses of sorbitol derivatives were determined in this way by MALDI-MS without thermal decomposition.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.132-133
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• 2003

편광 방향이 단일 모드로 유지되는 광섬유와 파장이 780nm인 반도체 레이저를 사용하여 간결한 구조의 beam scanning 타입의 비편광 공초점 현미경을 구성하였다. 일반적인 공초점 현미경은 세포내의 생명 현상을 보다 잘 이해 할 수 있는 장비이기 때문에 기존의 현미경으로는 연구할 수 없던 생명현상을 연구할 수 있도록 여러 가지 강력한 연구수단을 제공하고 있다. 살아 움직이는 생명체를 관찰할 수 있는 공초점 현미경에서 중요한 것은 속도와 투과 깊이이고, 장기의 표면을 관찰하기 위해서는 크기가 작아야 한다. (중략)

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.356-361
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• 2001

The effect of side-lobe on axial image is investigated. We show, using computer simulation and experimentally, that an optimized axial response can be achieved by minimized side-lobe according to the Herschel condition and that the appearance of sidelobes is decreased by balancing phase error.

• Parasites, Hosts and Diseases
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• v.42 no.4
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• pp.185-193
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• 2004

Toxoplasma gondii is an obligate intracellular protozoan parasite, which invades a wide range of hosts including humans. The exact mechanisms involved in its invasion are not fully understood. This study focused on the roles of $Ca^{2+}$ in host cell invasion and in T. gondii replication. We examined the invasion and replication of T. gondii pretreated with several calcium modulators, the conoid extrusion of tachyzoites. Calmodulin localization in T. gondii were observed using the immunogold method, and $Ca^{2+}$ levels in tachyzoites by confocal microscopy. In light microscopic observation, tachyzoites co-treated with A23187 and EGTA showed that host cell invasion and intracellular replication were decreased. The invasion of tachyzoites was slightly inhibited by the $Ca^{2+}$ channel blockers, bepridil and verapamil, and by the calmodulin antagonist, calmidazolium. We observed that calcium saline containing A23187 induced the extrusion of tachyzoite conoid. By immunoelectron microscopy, gold particles bound to anti-calmodulin or anti-actin mAb, were found to be localized on the anterior portion of tachyzoites. Remarkably reduced intracellular $Ca^{2+}$ was observed in tachyzoites treated with BAPTA/AM by confocal microscopy. These results suggest that host cell invasion and the intracellular replication of T. gondii tachyzoites are inhibited by the calcium ionophore, A23187, and by the extracellular calcium chelator, EGTA.

• Imaging Science in Dentistry
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• v.31 no.4
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• pp.227-233
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• 2001

Purpose: The purpose of this study was to investigate the apoptosis induction in tissues constituting the craniofacial region of growing rat by irradiation. Materials and Methods: The submandibular gland, brain, articular cartilage of condylar head, and calvarium were extracted from 20-day-old rats irradiated 10 Gy. Apoptosis of each tissue was examined by DNA fragmentation and estimated quantitatively using apoptotic index on TUNEL assay. Apoptotic index of each tissue was calculated by the equation for apoptotic cells/total cells × 1,000 on the images of confocal laser scanning microscopy. Apoptotic index was analyzed statistically according to the time lapse after irradiation on the tissues. Results : In the submandibular gland, apoptotic index was significantly increased from 6 hours after irradiation showing the highest value at 12 hours and decreased to the control level at 3 days after irradiation. In the brain, apoptotic index was abruptly reached to the maximum value at 6 hours after irradiation and decreased to the control level at 4 days after irradiation. Articular cartilage and calvarium showed no or little apoptotic signals. The results obtained by the apoptotic index accorded with that of DNA fragmentation. Conclusion : Radiation was closely related with the apoptosis of submandibular gland and brain but, not related with the apoptosis of the articular cartilage of condylar head and calvarium. The changes induced by radiation of the hard tissues would not be explained by apoptosis.

• The Korean Journal of Physiology
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• v.30 no.2
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• pp.197-208
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• 1996

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.239-247
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• 2001

The Fluorescence-Activated Cell Sorter (FACS) is a well-established instrument used for identifying, enumerating, classifying and sorting cells by their physical and optical characteristics. For a miniaturized FACS device, a disposable plastic microchip has been developed which has a hydrodynamic focusing chamber using soft lithography. As the characteristics of the spatially confined sample stream have an effect on sample throughput, detection efficiency, and the accuracy of cell sorting, systematic fluid dynamic studies are required. Flow visualization is conducted with a laser scanning confocal microscopy (LSCM), and three-dimensional flow structure of the focused sample stream is reconstructed from 2D slices acquired at $1\mutextrm{m}$ intervals in depth. It was observed that the flow structure in the focusing chamber is skewed by unsymmetrical velocity profile arising from trapezoidal cross section of the microchannel. For a quantitative analysis of a microscopic flow structure, Confocal Micro-PIV system has been developed to evaluate the accelerated flow field in the focusing chamber. This study proposes a method which defines the depth of the measurement volume using a detection pinhole. The trajectories of red blood cells (RBCs) and their interactions with surrounding flow field in the squeezed sample stream are evaluated to find optimal shape of the focusing chamber and fluid manipulation scheme for stable cell transporting, efficient detection, and sorting

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.392-398
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• 2003

We present a novel concept of a phase-shifting diffraction-grating interferometer, which is intended for the optical testing of concave mirrors with high precision. The interferometer is configured with a single reflective diffraction grating, which performs multiple functions of beam splitting, beam recombination, and phase shifting. The reference and test wave fronts are generated by means of reflective diffraction at the focal plane of a microscope objective with large numerical aperture, which allows testing fast mirrors with low f-numbers. The fiber-optic confocal design is adopted for the microscope objective to focus a converging beam on the diffractive grating, which greatly reduces the alignment error between the focusing optics and the diffraction grating. Translating the grating provides phase shifting, which allows measurement of the figure errors of the test mirror to nanometer accuracy.

• IMMUNE NETWORK
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• v.1 no.3
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• pp.187-195
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• 2001

The expression of recombinant proteins fused to 26 kDa glutathione S-transferase (GST) extracted from Schistosoma japonicum represents an attractive system for purifiying proteins of interest in a single step using GST-affinity chromatography. In addition, the GST-tag is used conveniently for detecting fused proteins since its high solubility as well as its relatively small size rarely interferes with the biological activity of the fused protein. In this regard, the GST system is frequently applied for tracing fusion proteins in both prokaryotic and eukaryotic cells to elucidate the physiological interactions and functional compartments of proteins. To provide a further tool in analyzing GST-fusion proteins, a new monoclonal antibody, with a high specificity to the S. japonicum GST was produced. Methods: BALB/c mice were immunized both with recombinant S. japonicum GST proteins, and by the fusion of splenocytes from these mice with myeloma cells. From this, a new anti -GST monoclonal antibody, termed SARAH, was generated. The specificity and reactivity of this antibody was confirmed by ELISA and by Western blot analysis. Results: SARAH showed a high reactivity to recombinant GST and GST fusion protein but not with native mammalian GST proteins as derived from other species including humans, cows, rabbits and rats. The applicability of SARAH was further demonstrated by confocal laser scanning microscopy, where GST proteins that were expressed transiently in mouse fibroblast cells, were specifically detected without interference of endogenous GST. Conclusion: SARAH is new monoclonal antibody with a high specificity to recombinant GST proteins but not to endogenous GST in mammalian cells.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.120-127
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• 2020

The aim of this study was to evaluate the antimicrobial effect of photodynamic therapy (PDT) using plaque disclosing agent, 10 - 20 mM erythrosine, as a photosensitizer. Multispecies cariogenic biofilms containing Streptococcus mutans, Lactobacillus casei and Candida albicans were formed on hydroxyapatite disc. 20 μM, 10 mM and 20 mM erythrosine were applied as a photosensitizer for 3 minutes, and then light-emitting diode (LED) irradiated for 24 seconds. Colony-forming unit (CFU) were measured and biofilms were observed using confocal laser scanning microscopy (CLSM). CFU were significantly decreased in the PDT groups using 10 - 20 mM erythrosine (10 mM, 20mM) and the results were also confirmed by CLSM. This study confirms the high antimicrobial effect of photodynamic therapy using plaque disclosing agent as a photosensitizer.