• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2006.10a
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• pp.76-77
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• 2006

• Journal of Biomedical Engineering Research
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• v.20 no.2
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• pp.199-204
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• 1999

As the correct measuring of the light dosimetry in biological tissues give the important affection to the effect of PDT treatment we used Monte Carlo simulation to measure the light dosimetry on this study. The parameters using in experiments are the optical properties of the real biological tissue, and we used Henyey-Greenstein phase function among the phase functions. As we results, we displayed the result the change of Fluence rate and the difference against the previous theory was at least 0.35%. Biological tissues using in experiment were Human tissue, pig tissue, rat liver tissue and rabbit muscle tissue. The most of biological tissue have big scattering coefficient in visible wavelength which influences penetration depth. The penetration depth of human tissue in visible region is 1.5~2cm. We showed that it is possible to measure fluence rate and penetration depth within the biological tissues by Monte Carlo simulation very well.

• Macromolecular Research
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• v.12 no.4
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• pp.367-373
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• 2004

We have developed a rigorous heat treatment method to improve the biocompatibility of chitosan as a tissue-engineered scaffold. The chitosan scaffold was prepared by the controlled freezing and lyophilizing method using dilute acetic acid and then it was heat-treated at 110$^{\circ}C$ in vacuo for 1-3 days. To explore changes in the physicochemical properties of the heat-treated scaffold, we analyzed the degree of deacetylation by colloid titration with poly(vinyl potassium sulfate) and the structural changes were analyzed by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffractometry (WAXD), and lysozyme susceptibility. The degree of deacetylation of chitosan scaffolds decreased significantly from 85 to 30% as the heat treatment time increased. FT-IR spectroscopic and WAXD data indicated the formation of amide bonds between the amino groups of chitosan and acetic acids carbonyl group, and of interchain hydrogen bonding between the carbonyl groups in the C-6 residues of chitosan and the N-acetyl groups. Our rigorous heat treatment method causes the scaffold to become more susceptible to lysozyme treatment. We performed further examinations of the changes in the biocompatibility of the chitosan scaffold after rigorous heat treatment by measuring the initial cell binding capacity and cell growth rate. Human dermal fibroblasts (HDFs) adhere and spread more effectively to the heat-treated chitosan than to the untreated sample. When the cell growth of the HDFs on the film or the scaffold was analyzed by an MTT assay, we found that rigorous heat treatment stimulated cell growth by 1.5∼1.95-fold relative to that of the untreated chitosan. We conclude that the rigorous dry heat treatment process increases the biocompatibility of the chitosan scaffold by decreasing the degree of deacetylation and by increasing cell attachment and growth.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.366-377
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• 2001

Persistent organochlorine pesticides has been used intensively in agriculture for a long time. The occurrence of organochlorine pesticides in the environment and subsequently in parts of the food chains, results in the intake of these compounds by human and animal. The measurement of the levels of organochlorine pesticides in tissues or blood of human populations is a good marker in evaluating the extent of exposure and hazards. So, most countries have conducted initial monitoring programs to determine organochlorine pesticides and polychlorinated biphenyls in human tissues. But, in Korea, a few research has been reported. In this study, the legally prohibited organochlorines, such as, $\alpha$-BHC, $\beta$-BHC, ${\gamma}$-BHC, $\delta$-BHC, p,p'-DDT, p,p'-DDD, p,p'-DDE, endrin, dieldrin and aldrin were determined in human blood, brain, adipose tissue, kidney cortex and liver tissues collected at autopsy of 10 men and 10 women, 16~65 years of age. Almost all the organochlorine pesticides mentioned previously were determined in human tissue samples indicated that they have been widely distributed in Korean human body. No significant difference was found in the levels of organochlorine pesticides between sexes, districts and ages.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.5
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• pp.311-325
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• 2001

Tissue engineering scaffolds play a critical role in regulating the reconstructed human tissue development. Various types of scaffolds have been developed in recent years, including fibrous matrix and foam-like scaffolds. The design of scaffold materials has been investigated extensively. However, the design of physical structure of the scaffold, especially fibrous matrices, has not received much attention. This paper compares the different characteristics of fibrous and foam-like scaffolds, and reviews regulatory roles of important scaffold properties, including surface geometry, scaffold configuration, pore structure, mechanical property and bioactivity. Tissue regeneration, cell organization, proliferation and differentiation under different microstructures were evaluated. The importance of proper scaffold selection and design is further discussed with the examples of bone tissue engineering and stem cell tissue engineering. This review addresses the importance of scaffold microstructure and provides insights in designing appropriate scaffold structure for different applications of tissue engineering.

• Macromolecular Research
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• v.15 no.4
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• pp.370-378
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• 2007

Mechanical stimulation is known to activate several cellular signal transduction pathways, leading to the induction of signaling molecules and extracellular matrix (ECM) proteins, thereby modulating cellular activities, such as proliferation and survival. In this study, primary human dermal fibroblasts (HDFs) were seeded onto chitosan-based scaffolds, and then cultured for 3 weeks in a bioreactor under a cyclic strain of 1 Hz frequency. Compared to control samples cultured under static conditions, the application of a cyclic strain stimulated the proliferation of HDFs in I week, and by week 3 the thickness of the cell/scaffold composites increased 1.56 fold. Moreover, immunohistochemical staining of the culture media obtained from the cell/scaffold samples subjected to the cyclic strain, revealed increases in the expression and secretion of ECM proteins, such as fibronectin and collagen. These results suggest that the preconditioning of cell/scaffold composites with a cyclic strain may enhance the proliferation of HDFs, and even facilitate integration of the engineered artificial dermal tissue into the host graft site.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.393-398
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• 2018

This is the first study demonstrating the efficacy of menstrual blood-derived stem cell (MenSC) transplantation via decellularized human amniotic membrane (DAM), for the promotion of skin excisional wound repair. The DAM was seeded with MenSCs at the density of $3{\times}10^4cells/cm^2$ and implanted onto a rat's $1.50{\times}1.50cm^2$ full-thickness excisional wound defect. The results of wound closure and histopathological examinations demonstrated that the MenSC-seeded DAM could significantly improve the wound healing compared with DAM-treatment. All in all, our data indicated that the MenSCs can be a potential source for cell-based therapies to regenerate skin injuries.

• Journal of Korean Neurosurgical Society
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• v.42 no.2
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• pp.118-124
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• 2007

Objective : Adipose tissue is derived from the embryonic mesoderm and contains a heterogenous stromal cell population. Authors have tried to verify the characteristics of stem cell of adipose derived stromal cells (ADSCs) and to investigate immunohistochemical findings after transplantation of ADSC into rat brain to evaluate survival, migration and differentiation of transplanted stromal cells. Methods : First ADSCs were isolated from human adipose tissue and induced adipose, osseous and neuronal differentiation under appropriate culture condition in vitro and examined phenotypes profile of human ADSCs in undifferentiated states using flow cytometry and immunohistochemical study. Human ADSCs were transplanted into the healthy rat brain to investigate survival, migration and differentiation after 4 weeks. Results : From human adipose tissue, adipose stem cells were harvested and subcultured for several times. The cultured ADSCs were differentiated into adipocytes, osteoctye and neuron-like cell under conditioned media. Flow cytometric analysis of undifferentiated ADSCs revealed that ADSCs were positive for CD29, CD44 and negative for CD34, CD45, CD117 and HLA-DR. Transplanted human ADSCs were found mainly in cortex adjacent to injection site and migrated from injection site at a distance of at least 1 mm along the cortex and corpus callosum. A few transplanted cells have differentiated into neuron and astrocyte. Conclusion : ADSCs were differentiated into multilineage cell lines through transdifferentiation. ADSCs were survived and migrated in xenograft without immunosuppression. Based on this data, ADSCs may be potential source of stem cells for many human disease including neurologic disorder.

• Biomedical Science Letters
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• v.23 no.3
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• pp.230-237
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• 2017

Changes in the activity of alkaline phosphatase (ALP) isoenzymes and isoforms in human serum have a major diagnostic value, therefore the regulation of ALP activities is a valuable target for therapeutic interventions. To assess the pharmacological activity of retinoids, i.e., all-trans retinoic acid and 13-cis retinoic acid, their tissue-specific inhibitory effect on human serum ALP activity was elucidated by chemical inhibition methods, heat-sensitive inactivation, and wheat-germ lectin precipitation test. Retinoids showed significant inhibition of the total ALP activity in human serum at a concentration of 5 mM. All-trans retinoic acid (5 mM) and 13-cis retinoic acid (5 mM) inhibited ALP activities by up to 12% and 15%, respectively, compared to that by guanidine hydrochloride (200 mM). L-phenylalanine (100 mM) and urea (30 mM) had no further inhibitory effect on ALP activities in human serum pretreated with retinoids (5 mM). Retinoids significantly inhibited ALP activities by up to 20% compared with that of tetramisole (30 mM). The ALP activities in retinoid-pretreated serum remained unchanged after the heat inactivation process. These results suggest that retinoids are inhibitors of the intestinal ALP isoenzyme. Remarkably, retinoids revealed potent inhibitory activities against ALP in wheat-germ lectin precipitant serum, indicating that they also function as inhibitors of the bone ALP isoform. The results show that retinoids inhibit the specific tissue-derived human serum ALP activities, moreover, the inhibitory effect of retinoids against bone ALP activity suggests their clinical utility as monitoring and prevention of metastasis of bone cancer.

• Applied Microscopy
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• v.28 no.3
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• pp.283-297
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• 1998

Hemopoiesis and morphogenesis of the human fetal liver through from 10 to 32 weeks of gestation were investigated by light and electron microscopy. The results obtained were as follows. Hemopoiesis of fetal liver tissue was found from 10 to 32 weeks of gestation, but the hemopoiesis was decreased at 32 weeks of gestation. At the 32 weeks of gestation, matured erythrocytes were observed in the sinusoid, and formation of liver cell cord and portal triad were established. Differentiation of hepatic cell was characterized by the increase of amount of cell organelles within cytoplasm, decrease of hemopoietic cell, morphological change of nuclear envelope from folding form to round form during the developmental period. These results suggest that human fetal liver plays a hematopoietic function until bone marrow and spleen play their function, but morphology of liver at 32 weeks of gestation was differed with structure observed in liver of adult.