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Jifeng Sun,Yarong Wang,Jie Yang,Dewei Du,Zhanting Li,Junxia Wei,Angang Yang 생화학분자생물학회 2012 Experimental and molecular medicine Vol.44 No.11
Relative deficiency in production of glycoprotein hormone erythropoietin (Epo) is a major cause of renal anemia. This study planned to investigate whether the hypoxia-regulated system of Epo expression, constructed by fusing Epo gene to the chimeric phosphoglycerate kinase (PGK) hypoxia response elements (HRE) in combination with cytomegalovirus immediate-early (CMV IE) basal gene promoter and delivered by plasmid intramuscular injection, might provide a long-term physiologically regulated Epo secretion expression to correct the anemia in adenine-induced uremic rats. Plasmid vectors (pHRE-Epo) were synthesized by fusing human Epo cDNA to the HRE/CMV promoter. Hypoxia-inducible activity of this promoter was evaluated first in vitro and then in vivo in healthy and uremic rats (n = 30 per group). The vectors (pCMV-Epo) in which Epo expression was directed by a constitutive CMV gene promoter served as control. ANOVA and Student’s t-test were used to analyze between-group differences. A high-level expression of Epo was induced by hypoxia in vitro and in vivo. Though both pHRE-Epo and pCMV-Epo corrected anemia,the hematocrit of the pCMV-Epo-treated rats exceeded the normal (P < 0.05), but that of the pHRE-Epo-treated rats didn’t. Hypoxia-regulated system of Epo gene expression constructed by fusing Epo to the HRE/CMV promoter and delivered by plasmid intramuscular injection may provide a long-term and stable Epo expression and secretion in vivo to correct the anemia in adenine-induced uremic rats.
POSITIVE SOLUTIONS OF SINGULAR DIRICHLET PROBLEMS VIA VARIATIONAL METHODS
Sun, Juntao,Chu, Jifeng Korean Mathematical Society 2013 대한수학회지 Vol.50 No.4
In this paper, we establish the existence results for second order singular Dirichlet problems via variational methods. Some recent results are extended and improved. Examples are also given to illustrate the new results.
Positive solutions of singular Dirichlet problems via variational methods
Juntao Sun,Jifeng Chu 대한수학회 2013 대한수학회지 Vol.50 No.4
In this paper, we establish the existence results for secondorder singular Dirichlet problems via variational methods. Some recentresults are extended and improved. Examples are also given to illustratethe new results.
AL-Mg-Cr 합금에서 열가공공정 및 고용강화가 초소성에 미치는 영향
정병선,홍순익,맹덕영,이병훈,전계풍 (田繼豊) 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.3
The effect of transition elements and thermomechanical processing(TMP) on the superplastic behavior of Al-7%Mg-0.3%Cr alloys were examined and correlated to the microstructural evolution during superplastic deformation. To establish an optimum manufacturing process for the enhanced superplastic properties, different processing methods such as warm rolling and cold rolling were used. In cold rolled Al-7%Mg-0.3%Cr alloys with intermediate annealing. the maximum elongation (close to 730%) was observed at 530℃. On the other hand, low temperature superplasticity was not observed in Al-7%Mg-0.3%Cr alloys with the TMP developed by McNelley because of the suppression of continuous recrystallization due to the dispersion of intermetallics. However, when these TMPed Al alloys were tested at high enough temperatures above the recrystallization temperature, the maximum elongation reached approximately 400% In this study, the possible effect of solute-dislocation interaction on the high temperature ductility was also examined. The predicted strain rate range of high ductility associated with high strain rate sensitivity due to solute strengthening coincides with the range of high temperature superplasticity of Al-Mg alloys, suggesting solute strengthening may be contributory to high temperature superplasticity of Al-Mg alloy.