Browsing by Author "Kuo, Chien-Hung"

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Beneficial effects of exendin-4 treatment on syngeneic mouse islet transplantation
(2007-09-01)
Juang, Jyuhn-Huarng
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Kuo, Chien-Hung
;
Wu, Chun-Hsin
;
Juang, Charity
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生物科技學系
Dissociation kinetics of macrocyclic trivalent lanthanide complexes of 1-oxa-4,7,10-triazacyclododecane-4,10-diacetic acid (H(2)ODO2A)
(2014)
Chang, C. Allen
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Lin, Chih-Cheng
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Kuo, Chien-Hung
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交大名義發表
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生物科技學系
The dissociation rates of LnODO2A(+) complexes (ODO2A(2-) is the deprotonated dianion of the ligand H(2)ODO2A, 1-oxa-4,7,10-triazacyclododecane-4,10-diacetic acid) are all faster than those of the corresponding LnDO2A(+) complexes (DO2A(2-) is the deprotonated dianion of the ligand H(2)DO2A, 1,4,7,10-tetraazacyclododecane- 1,7-diacetic acid), consistent with the fact that LnODO2A(+) complexes are kinetically more labile and thermodynamically less stable than the corresponding LnDO2A(+) complexes, and H(2)ODO2A is not pre-organized for Ln(3+) ion complexation but H(2)DO2A is. The dissociation kinetics of selected trivalent lanthanide (Ln(3+), Ln=La, Pr, Eu, Er, Lu) complexes of the macrocyclic ligand H(2)ODO2A (1-oxa-4,7,10-triazacyclododecane-4,10-diacetic acid), LnODO2A(+), were studied in the [H+] range (0.1-2.4) x 10(-4) M in the temperature range 15-45 degrees C. Excess Cu2+ ions were used as the scavenger for the ligand in acetate-acetic acid buffer medium. The dissociation reactions are independent of [Cu2+] and follow the rate law k(obs) =k(d) + k(AC)[Acetate] + K\'k(lim)[H+]/(1 + K\'[H+]), where k(d), k(AC), and k(lim) are the respective dissociation rate constants for the [H+]-independent, acetate-assisted, and the [H+]-dependent limiting pathways; K\' is the equilibrium constant for the protonation reaction LnODO2A(+) + H+ < > LnODO2AH(2+). The dissociation rates of LnODO2A(+) complexes are all faster than those of the corresponding LnDO2A(+) complexes (DO2A(2-) is the fully deprotonated dianion of the ligand H(2)DO2A, 1,4,7,10-tetrazacyclo-dodecane-1,7- diacetic acid), consistent with the notion that LnODO2A(+) complexes are kinetically more labile and thermodynamically less stable than the corresponding LnDO2A(+) complexes, and H(2)ODO2A is not pre-organized for Ln(3+) ion complexation but H(2)DO2A is.
Exendin-4 treatment expands graft beta-cell mass in diabetic mice transplanted with a marginal number of fresh islets
(2008-01-01)
Juang, Jyuhn-Huarng
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Kuo, Chien-Hung
;
Wu, Chun-Hsing
;
Juang, Charity
;
生物科技學系
Exendin-4 stimulates insulin secretion, suppresses glucagons secretion, increases beta-cell replication and neogenesis, and reduces beta-cell apoptosis. However, it has been shown that posttransplant exendin-4 treatment did not improve glucose homeostasis in diabetic mice transplanted with a large number of freshly isolated islets. The aim of this study was to test if exendin-4 is beneficial for hyperglycemic recipients with a marginal number of fresh islets. We transplanted 150 C57BL/6 mouse islets under the kidney capsule of inbred streptozotocin-diabetic mice, and then treated the recipients with and without exendin-4 for 6 weeks. Before and after transplantation, recipients' blood glucose, body weight, and intraperitoneal glucose tolerance test were measured. At 6 weeks, the grafts were removed to determine beta-cell mass. Blood glucose levels in both groups decreased progressively after transplantation, and the exendin-4-treated group had had lower blood glucose than controls since day 3. By 6 weeks, euglycemia was achieved more in mice treated with exendin-4 than in controls (100% vs. 62.5%, p = 0.018). The time to obtain normoglycemia was shorter in the exendin-4-treated group than in controls (12 +/- 8 vs. 29 +/- 13 days, p < 0.001). Blood glucose at 6 weeks was 123 +/- 18 and 170 +/- 62 mg/dl in the exendin-4-treated group and controls, respectively (p = 0.008). Additionally, the exendin-4- treated group had better glucose tolerance than controls at 2 and 4 weeks (p < 0.02). However, both groups exhibited increased body weight over time, and weight changes did not significantly differ between the two groups throughout the study period. At 6 weeks after transplantation, grafts in the exendin-4-treated group were more prominent and contained more insulin-stained cells than those of controls. They had 2.3-fold beta-cell mass of the graft compared with controls (0.30 +/- 0.11 vs. 0.13 +/- 0.03 mg, p = 0.012). These results indicate posttransplant exendin-4 treatment in the diabetic recipient with a marginal number of fresh islets expands graft beta-cell mass and improves transplantation outcome.
Exendin-4 treatment expands graft beta-cell mass in diabetic recipients with a marginal number of fresh islets
(2008-03-20)
Juan, Jyuhn-Huarng
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Kuo, Chien-Hung
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Wu, Chun-Hsing
;
Juang, Charity
;
生物科技學系
Magnetic Resonance Imaging of Mouse Islet Grafts Labeled with Novel Chitosan-Coated Superparamagnetic Iron Oxide Nanoparticles
(2013-04-29)
Juang, Jyuhn-Huarng
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Shen, Chia-Rui
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Wang, Jiun-Jie
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Kuo, Chien-Hung
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Chien, Yu-Wen
Object: To better understand the fate of islet isografts and allografts, we utilized a magnetic resonance (MR) imaging technique to monitor mouse islets labeled with a novel MR contrast agent, chitosan-coated superparamagnetic iron oxide (CSPIO) nanoparticles. Materials and Methods: After being incubated with and without CSPIO (10 mu g/ml), C57BL/6 mouse islets were examined under transmission electron microscope (TEM) and their insulin secretion was measured. Cytotoxicity was examined in alpha (alpha TC1) and beta (NIT-1 and beta TC) cell lines as well as islets. C57BL/6 mice were used as donors and inbred C57BL/6 and Balb/c mice were used as recipients of islet transplantation. Three hundred islets were transplanted under the left kidney capsule of each mouse and then MR was performed in the recipients periodically. At the end of study, the islet graft was removed for histology and TEM studies. Results: After incubation of mouse islets with CSPIO (10 mu g/mL), TEM showed CSPIO in endocytotic vesicles of alpha- and beta-cells at 8 h. Incubation with CSPIO did not affect insulin secretion from islets and death rates of alpha TC1, NIT-1 and beta TC cell lines as well as islets. After syngeneic and allogeneic transplantation, grafts of CSPIO-labeled islets were visualized on MR scans as persistent hypointense areas. At 8 weeks after syngeneic transplantation and 31 days after allogeneic transplantation, histology of CSPIO-labeled islet grafts showed colocalized insulin and iron staining in the same areas but the size of allografts decreased with time. TEM with elementary iron mapping demonstrated CSPIO distributed in the cytoplasm of islet cells, which maintained intact ultrastructure. Conclusion: Our results indicate that after syngeneic and allogeneic transplantation, islets labeled with CSPIO nanoparticles can be effectively and safely imaged by MR.
Magnetic resonance imaging of transplanted mouse islets labeled with chitosan-coated superparamagnetic iron oxide nanoparticles
(2009-09-01)
Juang, Jyuhn-Huarng
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Shen, Chia-Rui
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Wang, Jiun-Jie
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Kuo, Chien-Hung
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Chien, Yu-Wen
Synthesis and characterization of polyimide-silica nanocomposites using novel fluorine-modified silica nanoparticles
(2007-04-15)
Mo, Te-Cheng
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Wang, Hong-Wen
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Chen, San-Yan
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Dong, Rui-Xuan
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Kuo, Chien-Hung
Polyimide-silica nanocomposites were synthesized with 4,4'-oxydianiline, 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride), and fluorine-modified silica nanoparticles. Fluorinated precursors such as 4",4'"-(hexafluoroisopropylidene)bis(4-phenoxyaniline) (6FBPA) and 4,4'-(hexafluoroisopropylindene)diphenol (BISAF) were employed to modify the surface of the silica nanoparticles. The microstructures and thermal, mechanical, and dielectric properties of the polymide-silica nanocomposites were investigated. An improvement in the thermal stability and storage modulus of the polyimide nanocomposites due to the addition of the modified silica nanoparticles was observed. The microstructures of the polyimide-silica nanocomposites containing 6FBPA-modified silica exhibited more uniformity than those of the nanocomposites containing BISAF-modified silica. The dielectric constants of the polyimide were considerably reduced by the incorporation of pristine silica or 6FBPA-modified silica but not BISAF-modified silica. The addition of a modifier with higher fluorine contents did not ensure a lower dielectric constant. The uniformity of the silica distribution, manipulated by the reactivity of the modifier, played an important role in the reduction of the dielectric constant. Using 6FBPA-modified silica nanoparticles demonstrated an effective way of synthesizing low-dielectric-constant polyimide-silica nanocomposites. (c) 2007 Wiley Periodicals, Inc.