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        검색결과 6

        1.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was performed to identify the effect of synovium graft on conjunctiva in rabbits after dry eye induction. Six New Zealand White rabbits were used as dry eye models. Both eyes were divided to two groups as control and synovium graft group. The synovium graft was performed in fourth week after dry eye modeling. Quantitative change of tears through Schirmer tear test (STT), qualitative change of tear film through tear film break up time (TFBUT), and damage of cornea through fluorescein staining were observed for 10 weeks at intervals of two weeks. Histological examination was performed to evaluate cornea and conjunctiva at tenth week. In both groups, STT and TFBUT were significantly decreased in 4 weeks after modeling compared to 0 weeks (p < 0.05) . After synovium graft, there were increases in STT value at 4 weeks and TFBUT at 4 and 6 weeks in graft group (p < 0.05). Corneal fluorescein staining showed no significant difference between the two groups. In histopathological examination, grafted synovium was detected as round to ovoid ingression folds, well attached to grafted regions with 0.11 ± 0.04 mm2 (range, 0.05- 0.16 mm2). These results indicated that the synovium graft on the conjunctiva had an effect on the qualitative and quantitative improvement of the tear film even though there was no histological change.
        4,000원
        2.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Under the stressed condition, a complex feedback mechanism for stress is activated to maintain homeostasis of the body and secretes several stress hormones. But these stress hormones impair synthesis and secretion of the reproductive hormones, followed by suppression of ovarian function. Cytochrome P450 1A2 (CYP1A2) plays a major role in metabolizing exogenous substances and endogenous hormones, and its expression is recently identified at not only the liver but also several organs with respect to the pancreas, lung and ovary. Although the expression of CYP1A2 can be also affected by several factors, understanding for the changed pattern of the ovarian CYP1A2 expression upon stress induction is still limited. Therefore, CYP1A2 expression in the ovaries from immobilization stress-induced rats were assessed in the present study. The stress-induced rats in the present study exhibited the physiological changes in terms of increased stress hormone level and decreased body weight gains. Under immunohistological observation, the ovarian CYP1A2 expression in both control and the stressed ovary was localized in the antral to pre-ovulatory follicles. However, its expression level was significantly (p < 0.01) higher in the stress-induced group than control group. In addition, stress-induced group presented more abundant CYP1A2-positive follicles (%) than control group. Since expression of the ovarian CYP1A2 was highly related with follicle atresia, increased expression of CYP1A2 in the stressed ovary might be associated with changes of the ovarian follicular dynamics due to stress induction. We hope that these findings have important implications in the fields of the reproductive biology.
        4,000원
        3.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cytochrome P450 1A2 (CYP1A2) is a member of the cytochrome P450 superfamily enzymes in mammals and plays a major role in metabolizing endogenous hormones in the liver. In recent days, CYP1A2 expression has been found in not only the liver but also other tissues including the pancreas and lung. However, little information is available regarding the expression of CYP1A2 in the ovary, in spite of the facts that the ovarian follicle growth and atresia are tightly associated with controls of endocrine hormonal networks. Therefore, the expression of CYP1A2 in the ovaries of prepubertal and pubertal rats was investigated to assess its expression pattern and puberty-related alteration. It was demonstrated that the expression level of CYP1A2 was significantly (p < 0.01) higher in the pubertal ovaries than prepubertal counterparts. At the ovarian follicle level in both groups, whereas CYP1A2 expression was less detectable in the primordial, primary and secondary follicles, the strongly positive expression of CYP1A2 was localized in the granulosa cell layers in the antral and pre-ovulatory follicles. However, the ratio of CYP1A2-positive ovarian follicle was significantly (p < 0.01) higher in the ovary of pubertal group (73.1 ± 3.1%) than prepubertal one (41.0 ± 10.5%). During the Immunofluorescence, expression of CYP1A2 was mainly localized in Fas-positive follicles, indicating the atretic follicles. In conclusion, these results suggested that CYP1A2 expression was mainly localized at the atretic follicular cells and affected by the onset of puberty. Further study is still necessary but we hypothesize that CYP1A2 expresses in the atretic follicles to metabolize residue of the reproductive hormones. These findings may have important implications for the fields of reproductive biology of animals.
        4,000원
        4.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study is to investigate the influence of powder shape and densification mechanism on the microstructure and mechanical properties of Ti-6Al-4V components. BE powders are uniaxially and isostatically pressed, and PA ones are injection molded because of their high strengths. The isostatically compacted samples exhibit a density of 80%, which is higher than those of other samples, because hydrostatic compression can lead to higher strain hardening. Owing to the higher green density, the density of BE-CS (97%) is found to be as high as that of other samples (BE-DS (95%) and P-S (94%)). Furthermore, we have found that BE powders can be consolidated by sintering densification and chemical homogenization, whereas PA ones can be consolidated only by simple densification. After sintering, BE-CS and P-S are hot isostatically pressed and BE-DS is hot forged to remove residual pores in the sintered samples. Apparent microstructural evolution is not observed in BE-CSH and P-SH. Moreover, BE-DSF exhibits significantly fine grains and high density of low-angle grain boundaries. Thus, these microstructures provide Ti-6Al-4V components with enhanced mechanical properties (tensile strength of 1179 MPa).
        4,000원
        5.
        2015.12 구독 인증기관 무료, 개인회원 유료
        The objective of the present study was to examine the effects of β-glucan originating from Aureobasidium on full-thickness skin wound healing in diabetic C57BL/KsJ-db/db mouse models. In the diabetic C57BL/KsJ-db/db model, test articles were topically applied twice a day for 20 days starting from 1 day after wounding. The results were compared to that of MadecassolTM ointment (madecassol; 1% Centella asiatica extracts) topically applied at a concentration of 100 mg/kg. Treatment with β-glucan resulted in significant (p<0.01 or p<0.05) and dose-dependent decreases in wound size compared with that of vehicle control showing increased wound size (WS, %). In addition, 50% contraction time (CT50) was dramatically and dose-dependently reduced, and inflammatory cells in granulation tissues of the wound area were significantly (p<0.01 or p<0.05) and dose-dependently reduced compared with that of vehicle control showing increased numbers of micro-vessels and fibroblasts as well as re-epithelialization. In the madecassol group, similar changes in inflammatory cells and fibroblasts with re-epithelialization were also observed, but madecassol did not influence angiogenesis. No meaningful changes in body weight were detected in all tested groups compared with the vehicle control. Therefore, these data suggest that β-glucan has a beneficial effect on diabetic delayed skin wound healing and may be useful to manage incurable skin wounds in diabetic animals.
        4,000원
        6.
        2013.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nickel-based superalloy IN 713C powders have been consolidated by hot isostatic pressing (HIPing). The microstructure and mechanical properties of the superalloys were investigated at the HIPing temperature ranging from 1030o C to 1230o C. When the IN 713C powder was heated above γ' solvus temperature (about 1180o C), the microstruc- ture was composed of the austenitic FCC matrix phase γ plus a variety of secondary phases, such as γ' precipitates in γ matrix and MC carbides at grain boundaries. The yield and tensile strengths of HIPed specimens at room temperature were decreased while the elongation and reduction of area were increased as the processing temperature increased. At 700o C, the strength was similar regardless of HIPing temperature; however, the ductility was drastically increased with increasing the temperature. It is considered that these properties compared to those of cast products are originated from the homogeneity of microstructure obtained from a PM process.
        4,000원