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THE ROLE OF THE ELECTRON-PHONON INTERACTION IN THE MAGNETIZATION BEHAVIOR OF METALLIC FERROMAGNETS
Maki, Y.,Fukumoto, S.,Kim, D.J.,Tamada, T.,Antonoff, M. M.,Lee, K. H. 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.17 No.-
We show that the effect of the electron-phonon interaction in the ferromagnetic state of an itinerant electron ferromagnet results in an effective magnetic field and modifies the spin splitting of the electron energy bands. From a numerical calculation with a simple model electronic structure we find that such phonon effect can be much larger than ordinarily anticipated; the effect on the saturation magnetization can be as large as∼1μ_B/atom, and that on the temperature dependence of magnetization can significantly reduce the Curie temperature.
Oxidative Stress Interferes With White Matter Renewal After Prolonged Cerebral Hypoperfusion in Mice
Miyamoto, Nobukazu,Maki, Takakuni,Pham, Loc-Duyen D.,Hayakawa, Kazuhide,Seo, Ji Hae,Mandeville, Emiri T.,Mandeville, Joseph B.,Kim, Kyu-Won,Lo, Eng H.,Arai, Ken American Heart Association, Inc. 2013 Stroke Vol.44 No.12
<P><B>Background and Purpose—</B></P><P>White matter injury caused by cerebral hypoperfusion may contribute to the pathophysiology of vascular dementia and stroke, but the underlying mechanisms remain to be fully defined. Here, we test the hypothesis that oxidative stress interferes with endogenous white matter repair by disrupting renewal processes mediated by oligodendrocyte precursor cells (OPCs).</P><P><B>Methods—</B></P><P>In vitro, primary rat OPCs were exposed to sublethal CoCl<SUB>2</SUB> for 7 days to induce prolonged chemical hypoxic stress. Then, OPC proliferation/differentiation was assessed. In vivo, prolonged cerebral hypoperfusion was induced by bilateral common carotid artery stenosis in mice. Then, reactive oxygen species production, myelin density, oligodendrocyte versus OPC counts, and cognitive function were evaluated. To block oxidative stress, OPCs and mice were treated with the radical scavenger edaravone.</P><P><B>Results—</B></P><P>Prolonged chemical hypoxic stress suppressed OPC differentiation in vitro. Radical scavenging with edaravone ameliorated these effects. After 28 days of cerebral hypoperfusion in vivo, reactive oxygen species levels were increased in damaged white matter, along with the suppression of OPC-to-oligodendrocyte differentiation and loss of myelin staining. Concomitantly, mice showed functional deficits in working memory. Radical scavenging with edaravone rescued OPC differentiation, ameliorated myelin loss, and restored working memory function.</P><P><B>Conclusions—</B></P><P>Our proof-of-concept study demonstrates that after prolonged cerebral hypoperfusion, oxidative stress interferes with white matter repair by disrupting OPC renewal mechanisms. Radical scavengers may provide a potential therapeutic approach for white matter injury in vascular dementia and stroke.</P>
Dual effects of carbon monoxide on pericytes and neurogenesis in traumatic brain injury
Choi, Yoon Kyung,Maki, Takakuni,Mandeville, Emiri T,Koh, Seong-Ho,Hayakawa, Kazuhide,Arai, Ken,Kim, Young-Myeong,Whalen, Michael J,Xing, Changhong,Wang, Xiaoying,Kim, Kyu-Won,Lo, Eng H Nature Publishing Group 2016 Nature medicine Vol. No.
<P>At low levels, carbon monoxide (CO) has physiological roles as a second messenger and neuromodulator(1,2). Here we assess the effects of CO in a mouse model of traumatic brain injury (TBI). Treatment with CO-releasing molecule (CORM)-3 reduced pericyte death and ameliorated the progression of neurological deficits. In contrast, although treatment with the radical scavenger N-tert-butyl-a-phenylnitrone (PBN) also reduced pericyte death, neurological outcomes were not rescued. As compared to vehicle-treated control and PBN-treated mice, CORM-3-treated mice showed higher levels of phosphorylated neural nitric oxide synthase within neural stem cells (NSCs). Inhibition of nitric oxide synthase diminished the CORM-3-mediated increase in the number of cells that stained positive for both the neuronal marker NeuN and 5-bromo-2'-deoxyuridine (BrdU; a marker for proliferating cells) in vivo, consequently interfering with neurological recovery after TBI. Because NSCs seemed to be in close proximity to pericytes, we asked whether cross-talk between pericytes and NSCs was induced by CORM-3, thereby promoting neurogenesis. In pericyte cultures that were undergoing oxygen and glucose deprivation, conditioned cell culture medium collected after CORM-3 treatment enhanced the in vitro differentiation of NSCs into mature neurons. Taken together, these findings suggest that CO treatment may provide a therapeutic approach for TBI by preventing pericyte death, rescuing cross-talk with NSCs and promoting neurogenesis.</P>
이원일,이명규,Lee W. I.,H. Tsujii,T. Maki,Lee M. G. The Korean Society of Animal Environmental Science 2004 축산시설환경학회지 Vol.10 No.2
본 연구는 양돈 분뇨를 고온호기산화장치(TAO)를 이용하여 처리하였을 때, 고온 미생물 의 첨가에 의한 온도 상승과 시스템의 내부 미생물 변화 그리고 유해 미생물의 불활성화에 대하여 연구하였다. 실험은 총 용량 $18 m^3(3.0\times2.5\times2.4 m)$의 반응기에 양돈 분뇨 $6 m^3$을 투입하고 5$\~$7일간 운전하였다. 대조구는 양돈 분뇨만을 투입하였고 처리구는 6 $\iota$의 고온 미생물(Bacillus. sp)을 투입하였다. 반응기의 내부 미생물의 변화를 검토하기 위해서 호기성 중온균, 고온균 그리고 일반 세균을 분석하였다. 또한, 유해 미생물의 불활성화를 검토하기 위하여 E. coil, Salmonella. sp, Crytosporidium parvum, Giardia lamblia를 분석하였다. 대조구와 처리구의 운전기간 동안 반응기 내부의 온도 범위는 $18\~66^{\circ}C$로 $55^{\circ}C$ 이상의 높은 온도를 유지하였다. 미생물 변화에 있어서 대조구의 중온균과 고온균은 $3.1\times10^6\~1.2\times10^2$ CFU/ml, $1.0\times10^4\~8.0\times10^1$ CFU/ml로 감소하였으나 처리구의 경우, 중온균은 $3.0\times10^8\~8.6\times10^5$ CFU/ml로 감소하였으나 고온균은 $2.0\times10^6\~1.2\times10^8$ CFU/ml로 증가하는 경향을 보였다. Salmonella와 Giardia는 처리 전$\cdot$후에 검출되지 않았으며 E. coil와 Crytosporidium은 처리전 양성반응을 나타내었으나 처리 후 불활성화 되었다. 이상의 결과를 통해서, 우리는 TAO system에 고온 미생물을 첨가함으로써 유해한 미생물이 사멸된 액상비료를 생산할 수 있었고 분뇨로부터 기인하는 2차 오염을 방지할 수 있을 것으로 판단된다. This study analyzed temperature increase, microorganism changes, and inactivation of pathogenic microorganisms in pig slurry when treated with thermophilic microorganisms in Thermophilic Aerobic Oxidation(TAO) system. An amount of $6 m^3$ of pig slurry was treated in an $18 m^3(3.0\times2.5\times2.4 m)$ reactor for 5 to 7 days in two groups: the control of pig slurry only and the treatment of pig slurry with 6 liters of thermophilic microorganism(Bacillus sp.). To study the microorganism changes in the reactor, the populations of aerobic mesophilic microorganisms, thermophilic microorganisms and general pathogens were analyzed. To study the inactivation of pathogenic microorganisms, the levels of E. coli, Salmonella sp, Crytosporidium parvum and Giardia lamblia were analyzed. The temperature inside the reactor ranged from 18 to $62^{\circ}C$ for the control while far the treatment group it ranged from 18 to $66^{\circ}C$, showing a slightly higher array. With regard to changes in microorganisms, both mesophilic and thermophilic organisms decreased from $3.1\times10^6$ to $1.2\times10^2$ CFU/ml and from $1.0\times10^4$ to $8.0\times10^1$ CFU/ml, respectively, in the control. In the treatment, on the other hand, mesophilic organisms decreased from $3.0\times10^8$ CFU/ml to $8.6\times10^5$ CFU/ml while thermophilic organisms increased sharply from $2.0\times10^6$ to $1.2\times10^8$ CFU/ml. For pathogens, Salmonella and Giardia were not detected either before or after the treatment, while E. coli and C. parvum were found to be $10^5$ CFU/ml each before treatment and negative after it. From this experiment, it was concluded that thermophilic microorganisms could effectively sanitize liquid compost by generating high temperature in the TAO system, which in turn would inhibit the growth of pathogenic organisms.