유기용매에 의한 CYP2E1의 유도발현 : 단백질형성 효율의 증가에 따른 조절규제기전

김상건,Raymond F. Novak 한국독성학회 1993 Toxicological Research Vol.9 No.2

Pyridine and acetone are efficacious inducers of CYP2E1 in both rats and rabbits. The response in the elevation of CYP2E1 levels, changes in CYP2E1 mRNA levels, and enhanced translational processing of hepatic CYP2E1 mRNA during the early phase of CYP2E1 induction by the solvents pyridine and acetone were examined. Time-depen-dent incease in CYP2E1 levels occurred at early times (6-24h) following a single dose of pyridine treatmene, as assessed by Western immunoblot analysis, whereas the levels in CYP2E1 mRNA transiently decreased at 12h post-treatment, returning to the level present in untreated animals.

UV photoinitiated changes of humic fluorophores, influence of metal ions

Klementova, S.,Kriz, D.,Kopacek, J.,Novak, F.,Porcal, P. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.5

Fluorophore types and their photochemical stability have been tested in two samples of humic acids (HA) and four types of fulvic acids (FA) extracted from upper soil horizons (O and A horizons) in Norway spruce forest mountain ecosystems. Only one type of fluorophore occurred in all samples, with an excitation maximum at 310 nm for both HA and FA samples and emission maxima between 420-435 and 440-450 for HA and FA, respectively. HA weak native fluorescence increased significantly during irradiation in the first 12 h. Fluorophores in FA were uniformly degraded from the beginning of irradiation. Addition of metal (aluminium or ferric) ions did not affect the positions of fluorescence maxima in any of the studied samples; mild effects on fluorescence intensities were observed.

Plasticization for melt viscosity reduction of melt processable carbon fiber precursor

Batchelor, B.L.,Mahmood, S.F.,Jung, M.,Shin, H.,Kulikov, O.V.,Voit, W.,Novak, B.M.,Yang, D.J. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.98 No.-

<P>Fibers of polyacrylonitrile (PAN), or commonly referred to as acrylic fibers, are found to have many applications. Acrylic fibers are used as a textile medium for high quality and high performance yarns and fabrics, and also as the main supply of precursors for carbon fibers. The main reason of its use as carbon fiber precursor is that the polymer gives high mechanical properties with high carbon yield compared to other polymers. However, a major issue with current carbon fiber production from PAN is the use of a solvent spinning process for the preparation of polymer fiber precursor with hazardous solvents, and its safe reclamation. This study presents a solution by a solvent-free melt-spinning process with a copolymer produced from acrylonitrile (AN) with 1-vinylimidazole (VIM). A further significant improvement of the melt-spinning process is found with the additional use of a new oligomer as a plasticizer; the oligomer was prepared by polymerizing AN and methyl-2-(1H-imidazol-1-yl) acrylate (IA). The AN/VIM copolymer has glass transition temperature (T-g) of 115 degrees C but the plasticizer use lowers it to 75 degrees C. Thus, the oligomer plasticizer broadens the temperature range of melt-spinning processability. A carbon fiber prepared utilizing 8 wt% of the synthesized oligomer (Mn = 5 KDa) and high molecular weight base copolymer (Mn - 47 KDa), tensile strength of 1.9 GPa and modulus of 190 GPa have been achieved. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Osteoactivin inhibition of osteoclastogenesis is mediated through CD44-ERK signaling

Gregory R Sondag,Thomas S Mbimba,Fouad M Moussa,Kimberly Novak,Bing Yu,Fatima A Jaber,Samir M Abdelmagid,Werner J Geldenhuys,Fayez F Safadi 생화학분자생물학회 2016 Experimental and molecular medicine Vol.48 No.-

Osteoactivin is a heavily glycosylated protein shown to have a role in bone remodeling. Previous studies from our lab have shown that mutation in Osteoactivin enhances osteoclast differentiation but inhibits their function. To date, a classical receptor and a signaling pathway for Osteoactivin-mediated osteoclast inhibition has not yet been characterized. In this study, we examined the role of Osteoactivin treatment on osteoclastogenesis using bone marrow-derived osteoclast progenitor cells and identify a signaling pathway relating to Osteoactivin function. We reveal that recombinant Osteoactivin treatment inhibited osteoclast differentiation in a dose-dependent manner shown by qPCR, TRAP staining, activity and count. Using several approaches, we show that Osteoactivin binds CD44 in osteoclasts. Furthermore, recombinant Osteoactivin treatment inhibited ERK phosphorylation in a CD44-dependent manner. Finally, we examined the role of Osteoactivin on receptor activator of nuclear factor-κ B ligand (RANKL)-induced osteolysis in vivo. Our data indicate that recombinant Osteoactivin inhibits RANKL-induced osteolysis in vivo and this effect is CD44-dependent. Overall, our data indicate that Osteoactivin is a negative regulator of osteoclastogenesis in vitro and in vivo and that this process is regulated through CD44 and ERK activation.

유기용매에 의한 CYP2E1의 유도발현 : 단백질합성 효율의 증가에 따른 조절규제게전

김상건,Novak, Raymond F. 德成女子大學校 藥學硏究所 1993 藥學論文誌 Vol.4 No.1

Pyridine and acetone are efficacious inducers of CYP2E1 in both rats and rabbits. The response in the elevation of CYP2E1 levels, changes in CYP2E1 mRNA levels, and enhanced translational processing of hepatic CYP2E1 mRNA during the early phase of CYP2E1 induction by the solvents pyridine and acetone were examined. Time-dependent increase in CYP2E1 levels occurred at early times (6-24h) following a single dose of pyridine treatment, as assessed by Western immunoblot analysis, whereas the levels in CYP2E1 mRNA transiently decreased at 12 h post-treatment, returning to the level present in untreated animals. Autoradiographic analysis of [^14C]leucine-labeled microsomal proteins isolated at 6 h from the animals treated with the solvent showed an enhanced intensity of a band migrating in the region of CYP2E1, relative to control. The effects of pyridine on the distribution of CYP2E1 polysomal mRNA was examined to determine whether increased ribosomal loading on CYP2E1 mRNA is associated with the rapid induction of CYP2E1 protein. Northern and slot blot analyses of fractions from the cytoplasmic extracts using a CYP2E1-specific oligonucleotide probe revealed a shift in distribution of CYP2E1 message from monoribosomal fractions towards the heavier polyribosomal fractions following the solvent treatment, providing evidence that induction of CYP2E1 at early times following pyridine treatment involves enhanced translational efficiency through increased loading of ribosomes on CYP2E1 mRNA. These results suggest that induction of CYP2E1 occurs through an enhanced rate of protein synthesis in the absence of transcriptional activation.

Study of a melt processable polymer precursor for carbon fiber

Samsuddin F. Mahmood,Benjamin L. Batchelor,Minhye Jung,Kyusoon Park,Walter E. Voit,Bruce M. Novak,Duck Yang 한국탄소학회 2019 Carbon Letters Vol.29 No.6

Carbon fibers (CF) are predominantly being manufactured from polyacrylonitrile (PAN) based precursors which require solution spinning utilizing health hazardous organic solvent. This also adds to the cost of production due to the investment for the solvent recovery. Study of melt processable precursors has long been sought as a solution for health and environmental problems associated with the use of hazardous solvent. No use of solvent for spinning will also reduce the cost of manufacturing. Our coworker Deng et al. reported the possibility of using acrylonitrile-co-1-vinylimidazole (AN/VIM) copolymer as melt processable CF precursor. Here we report a successful preparation of carbon fiber from the co-polymer. We successfully demonstrated the preparation of thinner precursor fibers and carbon fibers through our optimization study of melt spinning, annealing, stabilization and carbonization.

Study of a melt processable polymer precursor for carbon fiber

Mahmood Samsuddin F.,Batchelor Benjamin L.,정민혜,박규순,Voit Walter E.,Novak Bruce M.,Yang Duck 한국탄소학회 2019 Carbon Letters Vol.29 No.6

Carbon fibers (CF) are predominantly being manufactured from polyacrylonitrile (PAN) based precursors which require solution spinning utilizing health hazardous organic solvent. This also adds to the cost of production due to the investment for the solvent recovery. Study of melt processable precursors has long been sought as a solution for health and environmental problems associated with the use of hazardous solvent. No use of solvent for spinning will also reduce the cost of manufacturing. Our coworker Deng et al. reported the possibility of using acrylonitrile-co-1-vinylimidazole (AN/VIM) copolymer as melt processable CF precursor. Here we report a successful preparation of carbon fiber from the co-polymer. We successfully demonstrated the preparation of thinner precursor fibers and carbon fibers through our optimization study of melt spinning, annealing, stabilization and carbonization.

The role of intracellular signaling in insulin-mediated regulation of drug metabolizing enzyme gene and protein expression

Kim, Sang K.,F. Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

Endogenous factors. including hormones, growth factors and cytokines, play an important role in the regulation of hepatic drug metabolizing enzyme expression in both physiological and pathophysiological conditions. Diabetes, fasting, obesity, protein-calorie malnutrition and long-term alcohol consumption produce changes in hepatic drug metabolizing enzyme gene and protein expression. This difference in expression alters the metabolism of xenobiotics, including procarcinogcns, carcinogens. toxicants and therapeutic agents, potentially impacting the efficacy and safety of therapeutic agents, and/or resulting in drug-drug interactions. Although the mechanisms by which xenobiotics regulate drug metabolizing enzymes haw been studied intensively, less is known regarding the cellular signaling pathways and components which regulate drug metabolizing enzyme gene and protein expression in response to hormones and cytokines. Recent findings, however. have revealed that several cellular signaling pathways are involved in hormone- and growth factor-mediated regulation of drug metabolizing enzymes. Our laboratory has reported that insulin and growth factors regulate drug metabolizing enzyme gene and protein expression. including cytochromes P450 (CYP), glutathione S-transferases (GST) and microsomal epoxide hydrolase (mEH), through receptors which are members of the large receptor tyrosine kinase (RTK) family, and by downstream effectors such as phosphatidylinositol 3-kinase, mitogen activated protein kinase (MAPK), Akt/protein kinase B (PKB), mammalian target of rapamycin (mTOR), and the p70 ribosomal protein S6 kinase (p70S6 kinase). Here, we review current knowledge of the signaling pathways implicated in regulation of drug metabolizing enzyme gene and protein expression in response to insulin and growth factors, with the goal ofincreasing our understanding of how disease affects these signaling pathways, components, and ultimately gene expression and translational control.

THE MITOGEN-ACTIVATED PROTEIN KINASE (MEK) INHIBITOR PD98059 ELEVATES PRIMARY CULTURED RAT HEPATOCYTE GLUTATHIONE LEVELS INDEPENDENT OF INHIBITING MEK

Kim, Sang K.,A. Abdelmegeed, Mohamed,F. Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

The antioxidant activity of flavonoids, directly through scavenging oxidizing species and indirectly through modulating drug-metabolizing enzyme activities, is associated with chemopreventive and chemotherapeutic effects. However, little published information is available concerning the effect of flavonoids on glutathione (GSH) homeostasis. We previously demonstrated that PD98059 (2'-amino-3'-methoxyflavone), a flavone derivative and selective mitogenactivated protein kinase kinase (MEK) 1 inhibitor, enhanced the insulin-mediated increase in GSH levels (J Pharmacal Exp Ther 311:99-108). To determine whether the PD98059-mediated increase in GSH levels was associated with MEK inhibition, primary cultured rat hepatocytes were treated with PD98059, the MEK inhibitor U0126, which is not a flavone derivative, or flavone. PD98059 increased GSH levels in a concentration-dependent manner in hepatocytes cultured in the presence or absence of insulin. In contrast, GSH levels were not affected by U0126 at concentrations sufficient to inhibit insulin-mediated extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Flavone, however, markedly increased GSH levels without inhibition of ERK1/2 phosphorylation. The concentration of GSH in the culture medium was also elevated by PD98059 or flavone, suggesting that the cellular GSH elevation could not be accounted for by the inhibition of GSH efflux into medium. Interestingly, PD98059 and flavone increased cellular cysteine levels, which may be responsible for the PD98059 and flavone-mediated elevation of GSH levels. These results provide evidence that PD98059 and flavone produce dramatic changes in GSH homeostasis in hepatocytes, through a mechanism(s) unrelated to MEK inhibition. Moreover, the current study implies that flavonoid-induced chemopreventive and chemotherapeutic effects may be mediated by regulation of redox state through the stimulation of GSH synthesis.

Identification of the Insulin Signaling Cascade in the Regulation of Alpha-Class Glutathione S-Transferase Expression in Primary Cultured Rat Hepatocytes

Kim, Sang K.,A.Abdelmegeed, Mohamed,F.Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

We reported previously that insulin elevated alpha-class glutathione S-transferase (GSTs) protein levels in primary cultured rat hepatocytes (Kim et al., 2003b). In contrast, glucagon down-regulated alpha- and pi-class GST expression, and mechanistic research implicated cAMP and protein kinase A in this process (Kim et al., 2003b). The present study examines the signaling pathways involved in the regulation of alpha-class GST in response to insulin in primary cultured rat hepatocytes. Protein levels of GSTA1/2 and GSTA3/5 and activity of GST toward 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD) were increased in an insulin concentration-dependent manner. Treatment of cells with the phosphatidylinositol 3-kinase (Pl3K) inhibitors wortmannin and LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one) or rapamycin, an inhibitor of mammalian target of rapamycin and ribosomal p70 S6 kinase (p70S6K) phosphorylation, or with an adenovirus containing green fluorescent protein and a dominant-negative and kinase-dead Akt, effectively inhibited the insulin-mediated increase in alphaclass GST expression and GST activity toward NBD. In contrast, PD98059 (2´-amino-3´-methoxyflavone), an inhibitor of mitogen-activated protein kinase kinase, SP600125 (1,9-pyrazoloanthrone), an inhibitor of c-Jun N-terminal kinase, SB203580 [4-(4-fluorophenyl)-2 -(4- methylsulfinylphenyl)-5-(4-pyridyl)1H-imadazole], an inhibitor of p38 mitogen-activated protein kinase, or bisindolylmaleimide, a broad spectrum inhibitor of protein kinase C, did not inhibit the insulin-mediated increase in alpha-class GST protein levels in hepatocytes. These results show that Pl3K/Akt/p70S6K signaling is active in the insulin-mediated up-regulation of the antioxidant defense system and that low insulin levels, as encountered in diabetes, potentially increase the susceptibility of hepatocytes to xeno-biotic-mediated and/or oxidative stress-mediated damage.