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Lee YM, Yen MH, Peng YY, Sheu JR, Chen YC, Chang MJ, Cheng CY. The antihypertensive and cardioprotective effects of (-)-MJ-451, an ATP-sensitive K(+) channel opener. Eur J Pharmacol 2000; 397:151-60. [PMID: 10844109 DOI: 10.1016/s0014-2999(00)00210-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
ATP-sensitive K(+) (K(ATP)) channel openers have been shown to be a potential class of therapeutic agents for the control of cardiovascular diseases, including angina, arrhythmias, and hypertension. In this study, the pharmacological activity of 6-cyano-3S,4R-dihydro-2, 2-dimethyl-2H-3-hydroxy-4-[5S-(1-hydroxymethyl)-2-oxo-1-pyrrolidinyl] -1-benzopyran ((-)-MJ-451), a synthetic K(ATP) opener, was evaluated in anesthetized rat models and in isolated rat thoracic rings. Results demonstrated that intravascular injection of (-)-MJ-451 (0. 02, 0.05 and 0.1 mg/kg) produced an immediate, dose-related reduction in mean arterial blood pressure in anesthetized spontaneously hypertensive rats (SHR), which persisted for more than 3 h and was not accompanied by reflex tachycardia. The hemodynamic changes were completely abolished by pretreatment with glibenclamide (4 mg/kg, i.v. bolus), a selective K(ATP) channel blocker. In isolated thoracic aorta, (-)-MJ-451 (10 nM-3 microM) produced a concentration-dependent vasodilator effect on the phenylephrine (0.3 microM)-induced vasoconstriction. Moreover, (-)-MJ-451 relaxed the thoracic aorta contracted by low (5, 20 and 30 mM), but not high (40 and 60 mM) concentrations of extracellular potassium. In addition, (-)-MJ-451 showed cardioprotective effects in the rat model of 45-min left coronary artery occlusion followed by 1-h reperfusion. In myocardial ischemia, pretreatment with (-)-MJ-451 (2, 5 and 10 microg/kg, i.v. bolus) significantly reduced the incidence of ventricular fibrillation and the mortality, also reducing the total number of ventricular premature contractions, total duration of ventricular tachycardia and ventricular fibrillation. A significant reduction in infarct size was noted in three (-)-MJ-451 (2, 5 and 10 microg/kg)-treated groups. Also, the cardioprotective effects of (-)-MJ-451 were virtually abolished by pretreating the rats with glibenclamide (4 mg/kg, i.v. bolus). In conclusion, (-)-MJ-451, through opening the K(ATP) channel, exerted antihypertensive and cardioprotective effects. Therefore, it is suggested that (-)-MJ-451 has potential in the treatment of hypertension or acute myocardial infarction.
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Chen HJ, Lee YM, Woung LC, Jou JR, Lin HJ. Scanning laser polarimetry in evaluation of retinal nerve fiber layer thickness for normal Taiwanese. Kaohsiung J Med Sci 2000; 16:223-32. [PMID: 10969517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Scanning laser polarimetry has been used recently for the measurement of retinal nerve fiber layer (RNFL) thickness, taking advantage of the birefrigence of the RNFL. We observe the RNFL with the instrument and try to find out a set of normal basic values of the RNFL thickness for clinical comparison. One hundred normal volunteers of different age groups were recruited for this study. There are 44 males and 56 females with a mean (1SD) age of 36.17(14.77) years. Three consecutive 15-degree polarimetric maps were acquired for each subject. RNFL thickness measurements were obtained at 1.75 disc diameters ring from the optic nerve. Four 90-degree quadrants were identified. As a result, the average of RNFL thickness is 90.69 (20.20) microns in the superior quadrant, 80.45 (17.4) microns in the inferior quadrant, 59.28 (15.37) microns in the nasal quadrant, and 48.98 (15.72) microns in the temporal quadrant with a mean thickness value of 69.86 (13.97) microns. Superior and inferior quadrants showed a comparatively thicker nerve fiber layer than nasal and temporal quadrants. The temporal quadrant was always the lowest. The axial length does not affect the RNFL thickness and no significant difference between males and females exists. However, an obvious inverse linear correlation between age and the RNFL thickness in all quadrants is found. The average RNFL thickness decreased with age by 0.26 micron per year. (R2 = 0.081, p-value = 0.004). When compared with the normal range, age-match would be necessary.
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Kim SY, Ha JC, Lee YM. Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)/poly(epsilon-caprolactone) (PCL) amphiphilic block copolymeric nanospheres. II. Thermo-responsive drug release behaviors. J Control Release 2000; 65:345-58. [PMID: 10699293 DOI: 10.1016/s0168-3659(99)00207-2] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Amphiphilic block copolymers composed of relatively hydrophilic PEO-PPO-PEO block copolymer (Pluronic) and poly (epsilon-caprolactone) with hydrophobic character were synthesized by ring-opening polymerization of epsilon-caprolactone in the presence of PEO-PPO-PEO block copolymer using stannous octoate as a catalyst. Pluronic/PCL block copolymeric nanospheres with core-shell structure were prepared by dialysis method. They showed the average diameter of 116-196 nm depending on the type of copolymer. All the nanosphere samples exhibited a narrow size distribution. The critical micelle concentrations of Pluronic/PCL amphiphilic block copolymers determined by fluorescence spectroscopy were lower than that of the common low molecular weight surfactant. Their core-shell structure was confirmed by 1H NMR spectroscopy. Pluronic/PCL block copolymeric nanospheres exhibited the reversible change of size depending on the temperature. Release behaviors of indomethacin from Pluronic/PCL block copolymeric nanospheres also showed temperature dependence and a sustained release pattern. In addition, cytotoxicity test using an MTT assay method revealed that these indomethacin-loaded Pluronic/PCL nanospheres could remarkably reduce the cell damage compared with the unloaded free indomethacin.
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Yu IJ, Chung YH, Maeng SH, Song KS, Lee YM, Chung HK, Kim HJ, Park JI, Lee SK, Lee YH, Chang JS. History of the Korean GLPs and the activities and perspectives of the Korean Society of GLP. QUALITY ASSURANCE (SAN DIEGO, CALIF.) 2000; 7:57-62. [PMID: 10707377 DOI: 10.1080/105294100277732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The Korean Society of Good Laboratory Practice (KSGLP) was established Dec. 10, 1998. The objectives of the KSGLP are to enhance the quality of domestic studies and the level of GLP compliance, in safety testing, and to promote information exchange among its members. The activities of KSGLP include: offering workshops and symposiums, linking with related governmental organizations, collecting GLP related information and providing the information to the related organizations, building international networks to collect information and to establish relationship, developing training materials and publishing periodicals, and other business necessary to achieve the objectives of the KSGLP. The KSGLP achieved its goals within a short period of time by offering workshops and symposia, and by providing important GLP related information in newspapers or via the KSGLP's internet homepage (www.ksglp.or.kr). The main role of the KSGLP will be to disseminate GLP technology nationwide. The KSGLP would like to help many labs that are preparing their facilities for GLP compliance. Further, the KSGLP is hoping to share GLP experiences with other members.
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Lee YM, Kaplan MM. Medical treatment of primary sclerosing cholangitis. JOURNAL OF HEPATO-BILIARY-PANCREATIC SURGERY 2000; 6:361-5. [PMID: 10664282 DOI: 10.1007/s005340050131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Until 1970, primary sclerosing cholangitis (PSC) was considered to be a medical curiosity. With the development of endoscopic cholangiography, PSC is now recognized more frequently and is a common indication for liver transplantation. PSC is usually progressive, leading to cirrhosis, portal hypertension, and liver failure. The manifestations of disease may be clinically similar to those of other causes of bile duct obstruction and must be distinguished from gallstone disease, bile duct carcinoma, primary biliary cirrhosis, and secondary biliary cirrhosis due to bile duct stricture. Medical management of PSC must take into account the likelihood that destroyed bile ducts do not regenerate as hepatocytes do. Hence, PSC should be treated early in its course. The goal of therapy is to prevent further damage and destruction of bile ducts. In this article, we will present relevant data concerning the medical management of primary sclerosing cholangitis.
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Lee YM, Park YJ, Lee SJ, Ku Y, Han SB, Choi SM, Klokkevold PR, Chung CP. Tissue engineered bone formation using chitosan/tricalcium phosphate sponges. J Periodontol 2000; 71:410-7. [PMID: 10776928 DOI: 10.1902/jop.2000.71.3.410] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Chitosan is a biodegradable natural polymer that has been shown to improve wound healing. This study aimed to develop chitosan/tricalcium phosphate (TCP) sponges as tissue engineering scaffolds for bone formation by three-dimensional osteoblast culture. METHODS The sponges were prepared by freeze-drying and cross-linking a mixture of chitosan solution with TCP. Fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 56 days. Cell proliferation, alkaline phosphatase (ALPase) activity, and calcium deposition in the cell-sponge constructs were measured at 1, 7, 14, 28, and 56 days. Histologic examination was performed with light microscopy and scanning electron microscopy. RESULTS Chitosan/TCP sponges supported the proliferation of osteoblastic cells as well as their differentiation as indicated by high ALPase activities and deposition of mineralized matrices by the cells. Light and scanning electron microscopic examination indicated that seeded osteoblastic cells were well attached to sponge matrices and proliferated in a multi-layer fashion. Small bone-like spicules were observed on the sponge matrix at 14 days. Seeded cells appeared to be embedded in the newly formed tissue matrix, which is characteristic of the osteoblast differentiation and their progression into osteocytic cells. The amount of mineralized tissue formed in the sponge at 56 days was significant. CONCLUSIONS These results suggest that the chitosan/TCP sponge is a feasible tool as a scaffolding material to grow osteoblast in a three-dimensional structure for transplantation into a site for bone regeneration.
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207
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Lee YM, Park YJ, Lee SJ, Ku Y, Han SB, Klokkevold PR, Chung CP. The bone regenerative effect of platelet-derived growth factor-BB delivered with a chitosan/tricalcium phosphate sponge carrier. J Periodontol 2000; 71:418-24. [PMID: 10776929 DOI: 10.1902/jop.2000.71.3.418] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND In order to achieve optimal effects, growth factors including platelet-derived growth factor (PDGF) should be delivered with a biodegradable carrier that will release therapeutic concentrations over a sufficient length of time. The purpose of this study was to evaluate the bone regenerative effect of PDGF-BB delivered with a chitosan/tricalcium phosphate (TCP) sponge carrier in a rat calvarial defect model. METHODS The PDGF-BB-loaded chitosan/TCP sponge carrier was fabricated by freeze-drying a mixture of chitosan solution and TCP powder and soaking in a PDGF-BB solution. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with 125I-labeled PDGF-BB. Chitosan/TCP sponges with and without PDGF-BB were implanted into 8 mm calvarial defects in rats. Rats were sacrificed at 2 and 4 weeks following implantation, and histologic and histomorphometrical examinations were performed. RESULTS In vitro evaluation demonstrated that an effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. In the histologic examination, the chitosan/TCP sponge carrier promoted osseous healing of the rat calvarial defects as compared to controls. The addition of PDGF-BB to the carrier further enhanced bone regeneration. Evidence of the degraded sponge matrix was observed mingled within the newly formed bone without connective tissue encapsulation. CONCLUSIONS The results of this study support the use of chitosan/TCP sponges as a delivery system for growth factors and demonstrate that PDGF-BB loaded onto chitosan/TCP sponge carriers has an osteogenic effect on bone regeneration in vivo.
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208
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Lee SW, Lee YM, Bae SK, Murakami S, Yun Y, Kim KW. Human hepatitis B virus X protein is a possible mediator of hypoxia-induced angiogenesis in hepatocarcinogenesis. Biochem Biophys Res Commun 2000; 268:456-61. [PMID: 10679226 DOI: 10.1006/bbrc.2000.2093] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The hepatitis B virus (HBV)-encoded transcriptional activator HBV-X protein (HBx) was known to be involved in hepatocarcinogenesis. Hepatocarcinogenesis generally included an active angiogenesis that was mainly considered to be due to a local hypoxia in liver tissues. However, the exact mechanisms of HBx-induced hepatocarcinogenesis were poorly understood. In this study, we examined the role of HBx in the increased angiogenesis and the possible regulating mechanisms of HBx by hypoxia. We demonstrated that HBx stimulated the transcription of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in HBx-stable transfectants. HBx-induced angiogenesis was confirmed by in vivo tumor angiogenesis assay, resulting in that the HBx transfectants increased the formation of new blood vessels compared to the control transfectants. Then, we demonstrated that the expression of HBx was enhanced after incubating HBV-infected hepatoma cells under hypoxia. Moreover, the activity of HBV enhancer 1 (Enh1) was increased when hepatoma cells transfected with the reporter plasmid containing HBV Enh1 were exposed to hypoxic conditions. These results strongly suggest that HBx may play a critical role in the hypoxia-induced angiogenesis through transcriptional activation of VEGF during hepatocarcinogenesis.
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209
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Adachi S, Morii E, Kim DK, Ogihara H, Jippo T, Ito A, Lee YM, Kitamura Y. Involvement of mi-transcription factor in expression of alpha-melanocyte-stimulating hormone receptor in cultured mast cells of mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:855-60. [PMID: 10623832 DOI: 10.4049/jimmunol.164.2.855] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The microphthalmia (mi) locus encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (MITF). We have reported that expression of several genes was impaired in cultured mast cells (CMCs) of mi/mi mice due to a defective transactivation ability of mutant MITF (mi-MITF). We also found that mi/mi CMCs did not express a receptor (MC1R) for alpha-melanocyte-stimulating hormone. The overexpression of the wild-type (+/+) MITF but not mi-MITF normalized the expression of the MC1R in mi/mi CMCs, indicating the involvement of +-MITF in the MC1R gene expression. Next, we analyzed the promoter region of the MC1R gene by the transient cotransfection assay. The luciferase construct under the control of the MC1R promoter and the cDNA-encoding +-MITF or mi-MITF were cotransfected into NIH/3T3 fibroblasts. The cotransfection of +-MITF but not mi-MITF increased the luciferase activity. There were five CANNTG motifs recognized by bHLH-Zip-type transcription factors in the cloned promoter region. We found +-MITF bound two of five CANNTG motifs, and both motifs were essential for the transactivation of the MC1R gene by +-MITF. These results indicated that +-MITF directly transactivated the MC1R gene through these two motifs.
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210
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Yu IJ, Maeng SH, Lee JY, Lee YM, Chung HK. Designation of a GLP facility by the Korean Ministry of Environment GLP authority: the case of the Center for Occupational Toxicology. QUALITY ASSURANCE (SAN DIEGO, CALIF.) 2000; 8:11-7. [PMID: 11710303 DOI: 10.1080/105294100753209156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
In this report, the process of designating a GLP facility by the Korean Ministry of Environment (MOE) is described in detail using the case of the Center of Occupational Toxicology (COT). The COT, which had been prepared as a GLP facility, filed an application to the National Institute of Environmental Research (NIER) of the MOE. The GLP system of the COT was evaluated by a harmonized evaluation team that consisted of several authorities including the NIER, the National Institute of Agricultural Science and Technology (NIAST), and the National Institute of Toxicological Research (NITR). The evaluation was arranged for mutual acceptance of data among GLP authorities. The designation process, additional documents necessary for applying GLP facility, the process of test facility evaluation including reviewing the application and site inspection, and inspection results and submission of correction plans are explained by using the instance of the inspection process of the COT. COT was evaluated as a suitable GLP facility for acute oral and inhalation toxicity tests and the Ames test.
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211
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Lee YM. Pediatric management problems. PEDIATRIC NURSING 2000; 26:84-5. [PMID: 12026319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
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212
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Park YJ, Lee YM, Park SN, Sheen SY, Chung CP, Lee SJ. Platelet derived growth factor releasing chitosan sponge for periodontal bone regeneration. Biomaterials 2000; 21:153-9. [PMID: 10632397 DOI: 10.1016/s0142-9612(99)00143-x] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
With an aim of improving bone regeneration, chitosan sponge containing platelet-derived growth factor-BB (PDGF-BB) were developed. For fabrication of chitosan sponge, chitosan solution was freeze-dried, crosslinked and freeze-dried again. PDGF-BB was incorporated into the chitosan sponge by soaking chitosan sponge into the PDGF-BB solution. Release kinetics of PDGF-BB, cell attachment, proliferation capacity and bony regenerative potentials of PDGF-BB-loaded chitosan sponge were investigated. Prepared chitosan sponge retained porous structure with 100 microm pore diameter that was suitable for cellular migration and growth. Release rate of PDGF-BB could be controlled by varying initial loading content of PDGF-BB to obtain optimal therapeutic efficacy. PDGF-BB-loaded chitosan sponge induced significantly high cell attachment and proliferation level, which indicated good cellular adaptability. PDGF-BB-loaded chitosan sponge demonstrated marked increase in new bone formation and rapid calcification. Degradation of the chitosan sponge was proceeded at defect site and subsequently replaced with new bone. Histomorphometric analysis confirmed that PDGF-BB-loaded chitosan sponge significantly induced new bone formation. These results suggested that chitosan sponge and PDGF-BB-loaded chitosan sponge may be beneficial to enhance periodontal bone regeneration.
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Lee OH, Bae SK, Bae MH, Lee YM, Moon EJ, Cha HJ, Kwon YG, Kim KW. Identification of angiogenic properties of insulin-like growth factor II in in vitro angiogenesis models. Br J Cancer 2000; 82:385-91. [PMID: 10646893 PMCID: PMC2363289 DOI: 10.1054/bjoc.1999.0931] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin-like growth factor II (IGF-II), highly expressed in a number of human tumours, has been recently known to promote neovascularization in vivo. Yet, the detailed mechanism by which IGF-II induces angiogenesis has not been well defined. In the present study, we explored an angiogenic activity of IGF-II in in vitro angiogenesis model. Human umbilical vein endothelial cells (HUVECs) treated with IGF-II rapidly aligned and formed a capillary-like network on Matrigel. In chemotaxis assay, IGF-II remarkably increased migration of HUVECs. A rapid and transient activation of p38 mitogen-activated protein kinase (p38 MAPK) and p125 focal adhesion kinase (p125FAK) phosphorylation was detected in HUVECs exposed to IGF-II. IGF-II also stimulated invasion of HUVECs through a polycarbonate filter coated with Matrigel. Quantitative gelatin-based zymography identified that matrix metalloproteinase-2 (MMP-2) activity generated from HUVECs was increased by IGF-II. This induction of MMP-2 activity was correlated with Northern blot analysis, showing in HUVECs that IGF-II increased the expression of MMP-2 mRNA, while it did not affect that of TIMP-2, a tissue inhibitor of MMP-2. These results provide the evidence that IGF-II directly induces angiogenesis by stimulating migration and morphological differentiation of endothelial cells, and suggest that IGF-II may play a crucial role in the progression of tumorigenesis by promoting the deleterious neovascularization.
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Ha JC, Kim SY, Lee YM. Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic)/poly(epsilon-caprolactone) (PCL) amphiphilic block copolymeric nanospheres. I. Preparation and characterization. J Control Release 1999; 62:381-92. [PMID: 10528075 DOI: 10.1016/s0168-3659(99)00167-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amphiphilic block copolymers based on PEO-PPO-PEO block copolymer (Pluronic) and poly(epsilon-caprolactone) were synthesized by bulk polymerization. The structural analysis of Pluronic/PCL block copolymer was carried out using FT-IR, 1H NMR, GPC, WAXD, DSC and TGA measurements. To prepare copolymeric nanospheres with a micellar structure, Pluronic/PCL amphiphilic block copolymers were dialyzed against water. The size and size distribution of Pluronic/PCL block copolymeric nanospheres were examined by dynamic light scattering measurement. They showed an average diameter of 116 to 196 nm depending on the type of copolymer. All the nanosphere samples exhibited a narrow size distribution. The critical micelle concentrations of Pluronic/PCL amphiphilic block copolymers determined by fluorescence spectroscopy were lower than that of common low molecular weight surfactants. We confirmed the formation of stable copolymeric nanospheres through the solution behavior of amphiphilic block copolymer in selective solvents.
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Bae SK, Bae MH, Ahn MY, Son MJ, Lee YM, Bae MK, Lee OH, Park BC, Kim KW. Egr-1 mediates transcriptional activation of IGF-II gene in response to hypoxia. Cancer Res 1999; 59:5989-94. [PMID: 10606246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
We have previously reported that the exposure of human HepG2 cells to hypoxic conditions results in the overexpression of human insulin-like growth factor II (IGF-II) mRNA whose size is 6.0 kb. This particular size of IGF-II mRNA is transcribed under the control of the IGF-II P3 promoter. In the present study, to delineate the molecular mechanism for the activation of the IGF-II gene, we examined the induction of P3 promoter activity in HepG2 cells by hypoxia in the transient expression system. In this system, hypoxia induced a linear increase within 24 h in the expression of luciferase that was driven by the IGF-II P3 promoter. To further delineate which factors mediate this response, the expression pattern of regulators of the P3 promoter, Egr-1, Sp1, and WT1, were analyzed by reverse transcription-PCR and Northern blot analysis. We found that hypoxia increased the expression of Egr-1 but not of Sp1. In contrast, the level of WT1, a repressor of IGF-II expression, was markedly decreased during hypoxia. The mRNA stability assay revealed that the induction of transcription is the mechanism of underlying Egr-1 mRNA elevation. We then investigated the effects of hypoxia on the DNA binding activity of Egr-1. Both electrophoretic mobility shift assay and supershift assay demonstrated that the DNA binding activity of the Egr-1 protein was increased by hypoxia. In addition, the level of Egr-1 protein was also increased under the hypoxia as determined by Western blot analysis. Cotransfection of HepG2 cells with an Egr-1 expression vector and an IGF-II P3 promoter-luciferase reporter plasmid showed that the transcription of IGF-II was activated by Egr-1 in a dose-dependent manner. Moreover, the elevation of IGF-II P3 promoter activity was induced synergistically by the cotreatment of hypoxia with Egr-1 overexpression. Deletion of sequences in the IGF-II P3 promoter containing Egr-1 binding sites did not respond to hypoxic stress. Taken together, these data strongly indicate that hypoxia-induced IGF-II expression in HepG2 cells is due to the enhanced activity of Egr-1 on the IGF-II P3 promoter and that the Egr-1 binding site in the IGF-II P3 promoter is essential for the transcriptional regulation of IGF-II under hypoxic conditions.
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Liau JJ, Cheng CK, Huang CH, Lee YM, Chueh SC, Lo WH. The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. Clin Biomech (Bristol, Avon) 1999; 14:717-21. [PMID: 10545626 DOI: 10.1016/s0268-0033(99)00027-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. DESIGN An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well. METHODS Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component. RESULTS The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses. CONCLUSIONS This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses. RELEVANCE This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.
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Huang CH, Lee YM, Lai JH, Liau JJ, Cheng CK. Failure of the all-polyethylene patellar component after total knee arthroplasty. J Arthroplasty 1999; 14:940-4. [PMID: 10614884 DOI: 10.1016/s0883-5403(99)90007-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
From 1991 to 1996, 953 cases of porous-coated anatomic modular knee prostheses with all-polyethylene patellar components were implanted. Among them, 4 cases had breakage of the patellar component at the peg-button interfaces. One had loosening of the patellar component by cutting out the patellar bony bed. Heavy body weight, weakness of the pegs of the all-polyethylene patellar component, and osteonecrosis of the patella were conceived as the causes of failure.
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218
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Jiang MJ, Yu YJ, Chen YL, Lee YM, Hung LS. Cyclic strain stimulates monocyte chemotactic protein-1 mRNA expression in smooth muscle cells. J Cell Biochem 1999; 76:303-10. [PMID: 10618646 DOI: 10.1002/(sici)1097-4644(20000201)76:2<303::aid-jcb13>3.3.co;2-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hemodynamic forces are important determinants for the formation of atherosclerotic plaques. The recruitment of circulating monocytes into the arterial wall is an important step during atherogenesis. Monocyte chemotactic protein-1 (MCP-1) has been shown to be a key factor for monocyte transmigration. This study examined the effects of cyclic strain on MCP-1 mRNA expression levels of cultured rat aortic smooth muscle cells. The MCP-1 mRNA levels of aortic smooth muscle cells first increased as the duration of cyclic strain increased, reaching the maximum at 6-12 h, maintained at high levels throughout the 48-h strain period. To explore signaling pathways mediating cyclic strain-stimulated MCP-1 mRNA expression, we examined the involvement of tyrosine kinase and protein kinase C (PKC). Tyrosine kinase inhibitors, genistein and tyrphostin 51, at 50 microM blocked cyclic strain-stimulated MCP-1 mRNA expression. Preincubation with a PKC activator, phorbol 12-myristate 13-acetate (PMA), 2 microM, for 24 h to downregulate PKC did not decrease cyclic strain-induced MCP-1 mRNA expression. A 6-h incubation with 0. 1 microM PMA to activate PKC, which stimulated MCP-1 expression when applied alone, abolished the stimulatory effects of cyclic strain. A specific PKC inhibitor, calphostin C (0.1 microM), diminished cyclic strain-stimulated MCP-1 mRNA expression. Angiotensin II at 10 or 1,000 nM induced a moderate upregulation of MCP-1 mRNA, and no synergistic effects were observed between angiotensin II and cyclic strain. These results indicate that cyclic strain stimulates MCP-1 mRNA expression in smooth muscle cells through signaling pathway(s) mediated by tyrosine kinase activation.
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Lee OH, Kim YM, Lee YM, Moon EJ, Lee DJ, Kim JH, Kim KW, Kwon YG. Sphingosine 1-phosphate induces angiogenesis: its angiogenic action and signaling mechanism in human umbilical vein endothelial cells. Biochem Biophys Res Commun 1999; 264:743-50. [PMID: 10544002 DOI: 10.1006/bbrc.1999.1586] [Citation(s) in RCA: 292] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid metabolite abundantly stored in platelets and released upon platelet activation. Recently, S1P has been postulated for its potential roles in angiogenesis. In this study, we provided several lines of evidence showing that S1P has angiogenic activity. In vitro, S1P stimulated DNA synthesis and chemotactic motility of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner, reaching a near maximum at 1 microM. S1P also significantly induced tube formation of HUVECs on Matrigel. Matrigel plug assay in mice revealed that S1P promotes angiogenesis in vivo. In addition, exposure of HUVECs to S1P led to rapid activation of extracellular signal-regulated kinases (ERKs) and p38 mitogen-activated protein kinase (p38 MAPK) in a pertussis toxin (PTX)-sensitive manner. Notably, HUVEC migration and tube formation in response to S1P were completely blocked by pretreatment with PTX. Further, the MEK inhibitor U0126 markedly inhibited S1P-induced tube formation but S1P-induced migration was not affected by inhibition of ERK and p38 MAPK. Taken together, these results indicate that S1P induces angiogenesis predominantly via G(i) protein-coupled receptors in endothelial cells and suggest that S1P may act as an important modulator of platelet-induced angiogenesis.
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Choi CY, Lee YM, Kim YH, Park T, Jeon BH, Schulz RA, Kim Y. The homeodomain transcription factor NK-4 acts as either a transcriptional activator or repressor and interacts with the p300 coactivator and the Groucho corepressor. J Biol Chem 1999; 274:31543-52. [PMID: 10531357 DOI: 10.1074/jbc.274.44.31543] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NK-4 (tinman) encodes an NK-2 class homeodomain transcription factor that is required for development of the Drosophila dorsal mesoderm, including heart. Genetic evidence suggests its important role in mesoderm subdivision, yet the properties of NK-4 as a transcriptional regulator and the mechanism of gene transcription by NK-4 are not completely understood. Here, we describe its properties as a transcription factor and its interaction with the p300 coactivator and the Groucho corepressor. We demonstrate that NK-4 can activate or repress target genes in cultured cells, depending on functional domains that are conserved between Drosophila melanogaster and Drosophila virilis NK-4 genes. Using GAL4-NK-4 fusion constructs, we have mapped a transcriptional activation domain (amino acids 1-110) and repression domains (amino acids 111-188 and the homeodomain) and found an inhibitory function for the homeodomain in transactivation by NK-4. Furthermore, we demonstrate that NK-4-dependent transactivation is augmented by the p300 coactivator and show that NK-4 physically interacts with p300 via the activation domain. In addition, cotransfection experiments indicate that the repressor activity of NK-4 is strongly enhanced by the Groucho corepressor. Using immunoprecipitation and in vitro pull-down assays, we show that NK-4 directly interacts with the Groucho corepressor, for which the homeodomain is required. Together, our results indicate that NK-4 can act as either a transcriptional activator or repressor and provide the first evidence of NK-4 interactions with the p300 coactivator and the Groucho corepressor.
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Lee YM, Peng YY, Sheu JR, Cheng CY, Yen MH. The effects of a newly synthesized ATP-sensitive potassium channel opener, MJ-355, on blood pressure and myocardial ischemia-reperfusion injury in rats. JAPANESE JOURNAL OF PHARMACOLOGY 1999; 81:185-93. [PMID: 10591476 DOI: 10.1254/jjp.81.185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
ATP-sensitive potassium (K(ATP)) channel openers, exerting a potent vasodilatory action, are useful in the treatment of cardiovascular disorders; e.g., hypertension and angina pectoris. This study was designed to evaluate the effect of MJ-355 (6-cyano-3,4-trans-3,4-dihydro-2,2-dimethyl-2H-3-hydroxy-4-[2-oxo-5S-(1- ethoxyethoxymethyl)-1-pyrrolidinyl]-1-benzopyran), a newly synthesized K(ATP) channel opener, on hemodynamics in spontaneously hypertensive rats and on myocardial ischemia-reperfusion injury in a rat model of 45 min left coronary artery occlusion followed by 1-h reperfusion. Intravascular injection of MJ-355 (0.005, 0.05 and 0.1 mg/kg) produced a dose-related reduction in mean arterial blood pressure. The depressor effect started 10-15 min after the administration and persisted for more than 3 h and was not accompanied by a reflex tachycardia. In myocardial ischemia, pretreatment of MJ-355 (0.02 mg/kg) significantly reduced the total number of ventricular premature contractions and ventricular tachycardia, total duration of ventricular fibrillation and the mortality. Additionally, a significant reduction in infarct size was noted in all of the MJ-355-treated groups. The hemodynamic and cardioprotective effects of MJ-355 were virtually abolished by pretreating the rats with glibenclamide (4 mg/kg, i.v. bolus), a selective K(ATP) channel blocker. In conclusion, MJ-355, through the activation of K(ATP) channels, exhibited antihypertensive and cardioprotective effects. It is suggested that MJ-355 should be useful in the treatment of hypertension and/or acute myocardial infarction.
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Chang CC, Hsiao KJ, Lee YM, Lin CM. Towards metabolic sink therapy for mut methylmalonic acidaemia: correction of methylmalonyl-CoA mutase deficiency in T lymphocytes from a mut methylmalonic acidaemia child by retroviral-mediated gene transfer. J Inherit Metab Dis 1999; 22:773-87. [PMID: 10518277 DOI: 10.1023/a:1005593605399] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The pathology associated with mut methylmalonic acidaemia (MMA) is caused by systemic accumulation of methylmalonate. Therefore, removal of methylmalonate from the circulation of affected individuals by an engineered metabolic system is proposed as a potential treatment. The haematopoietic cell is a potential site for such a metabolic system because of its direct contact with the accumulated metabolite and the demonstrated safety and ease in utilizing this cell. In this study, we assessed the feasibility of developing a haematopoietic cell-based methylmalonate sink by analysing propionate/methylmalonate metabolism in a variety of haematopoietic cells. The results show that propionate metabolism and methylmalonyl-CoA mutase (MCM) activity are intact in primary T cells, EBV-B cells, and CD34+ haematopoietic stem cell-derived granulocytes, whereas they are defective in those from a mut MMA child. Moreover, normal T and EBV-B cells clear methylmalonate from the medium at a significant rate. Transduction of MCM-deficient T cells with a recombinant retrovirus encoding the human MCM cDNA results in correction of propionate metabolism. These results establish the basis for developing haematopoietic cell-based metabolic sink therapy for mut MMA by T lymphocyte/haematopoietic stem cell-directed gene transfer.
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Choi YS, Hong SR, Lee YM, Song KW, Park MH, Nam YS. Studies on gelatin-containing artificial skin: II. Preparation and characterization of cross-linked gelatin-hyaluronate sponge. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1999; 48:631-9. [PMID: 10490676 DOI: 10.1002/(sici)1097-4636(1999)48:5<631::aid-jbm6>3.0.co;2-y] [Citation(s) in RCA: 173] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This study was conducted to develop a new sponge type of biomaterial to be used for either wound dressing or scaffold for tissue engineering. We were able to prepare an insoluble matrix composed of gelatin and sodium hyaluronate (HA) by dipping the soluble sponge into 90% (w/v) acetone/water mixture containing a small amount of cross-linking agent, 1-ethyl-3-3-dimethylaminoproplycarbodiimide hydrochloride, EDC. To characterize the sponge, Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and Instron analysis were performed. The obtained results indicate that the chemically cross-linked sponge shows a cross-linking degree of 10-35%, a mean pore size of 40-160 microm, porosity of 35-67%, and a tensile strength of 10-30 gf/cm(2). Especially, the porosity measured by image analysis showed a tendency to increase with HA content, resulting in an increased water uptake. The resistance to collagenase degradation in vitro increased for up to 2 days. Silver sulfadiazine (AgSD)-impregnated gelatin-HA sponge was also prepared and compared with conventional vaseline gauze by applying it onto a dorsal skin defect of wistar rat for 5, 12, and 21 days. Histological results showed an enhancement of wound healing in AgSD-impregnated gelatin-HA sponge.
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Yu IJ, Lee JY, Chung YH, Kim KJ, Han JH, Cha GY, Chung WG, Cha YN, Park JD, Lee YM, Moon YH. Co-administration of toluene and xylene antagonized the testicular toxicity but not the hematopoietic toxicity caused by ethylene glycol monoethyl ether in Sprague-Dawley rats. Toxicol Lett 1999; 109:11-20. [PMID: 10514026 DOI: 10.1016/s0378-4274(99)00063-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Occupational painters are exposed to ethylene glycol monoethyl ether (EGEE), a widely used emulsifying solvent known to cause testicular degeneration and bone marrow depression, together with toluene (TOL) and xylene (XYL) as a mixture. In the previous study (Chung et al., Tox. Lett. 104:143, 1999), testicular atrophy caused by EGEE (200 mg/kg) was shown to be antagonized by co-administration of TOL (250 mg/kg) and XYL (500 mg/kg). This study was conducted to provide histological support for the previously observed antagonistic protective effect of TOL + XYL on EGEE inducible testicular toxicity and to determine whether a similar antagonistic effect can be demonstrated against the EGEE derived hematopoietic toxicity. Compared to the extent of seminiferous tubule degeneration caused by EGEE (150 mg/kg, six times per week for 4 weeks), testes of rats given co-administration of TOL (250 mg/kg) + XYL (500 mg/kg) showed dramatically reduced tubular degeneration. Hyperplasia of Leydig cells in the interstitium was observed in both EGEE and EGEE + TOL + XYL-treated rats. Although a minimal dose of EGEE causing testicular atrophy was used, WBC and platelet counts were decreased significantly. In the TOL + XYL-treated control group, the WBC and platelet counts were not decreased. However, the bone marrow depression caused by EGEE was not reversed by the combined administration of TOL + XYL. In all experimental groups (EGEE alone, TOL + XYL, EGEE + TOL + XYL), plasma levels of creatinine and alkaline phosphatase were significantly decreased. In addition to the marked testicular atrophy, EGEE also decreased the weights of adrenal glands and epididymis. In conclusion, while the testicular degeneration caused by EGEE was antagonized by TOL + XYL, the EGEE derived hematopoietic suppression was not reversed.
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Hwu WL, Wang PJ, Hsiao KJ, Wang TR, Chiou YW, Lee YM. Dopa-responsive dystonia induced by a recessive GTP cyclohydrolase I mutation. Hum Genet 1999; 105:226-30. [PMID: 10987649 DOI: 10.1007/s004390051093] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
GTP cyclohydrolase I (GTPCH) catalyzes the rate-limiting step of tetrahydrobiopterin (BH4) biosynthesis. GTPCH has been associated with two clinically distinct human diseases: the recessive hyperphenylalaninemia (HPA) and the dominant dopa-responsive dystonia (DRD). We found a recessive GTPCH mutation (R249S, 747C-->G in a dystonia patient. Her PHA-stimulated mononuclear blood cells had a normal amount of GTPCH mRNA, but low GTPCH activity. Arginine 249 is located at the C-terminus of GTPCH, outside the catalytic site. E. coli expressed recombinant R249S mutant protein possessed normal enzyme activity and kinetics. However, in transfected eukaryotic cells, R249S mutant protein expression level was lower than the wild-type protein. Therefore, this is suspected to be a destabilizing mutation. Our data suggest that DRD could be either dominantly or recessively inherited, and the inheritance might be determined by the mechanism of mutation.
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