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조혈모세포이식 후 골성장인자의 변화 및 골대사에 미치는 영향 : Impact on Bone Mineral Metabolism
백기현,오은숙,오기원,이원영,김혜수,권순용,한제호,강무일,차봉연,이광우,손호영,강성구,김춘추 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.5
연구배경: 각종 장기이식의 시행이 많아지고 이식 후 생존율이 증가함에 따라 이식 후 합병증에 대한 관심 또한 높아지고 있다. 조혈모세포이식 후에도 다양한 내분비적 합병증이 발생할 수 있으며 골격에 대한 합병증도 문제점으로 대두되고 있다. 조혈모세포 이식 후 발생하는 골소실에는 이식 후 초기의 골형성 저하와 골흡수 증가가 중요한 역할을 담당하리라고 추측되는데 이러한 골재형성불일치(biochemical uncoupling)에 골 성장인자들이 미치는 영향에 대해서는 알려진 바가 없다. 본 연구에서는 조혈모세포이식 전, 후로 말초 혈액에서 IGF-I, FGF-2, M-CSF같은 성장인자의 변화를 알아보고, 이들 성장인자의 변화가 조혈모세포이식 후의 골형과 골흡수에 미치는 영향 및 이식 후 발생되는 골량 소실과의 연관성을 확인해 보고자 하였다. 방법: 여러 가지 혈액질환으로 인해 동종 골수이식을 시행 받은 환자들을 전향적으로 관찰하였으며 이식 전 및 이식 후 1주, 2주, 3주, 4주 및 3개월, 6개월 1년에 말초 혈액에서 골교체표지자를 측정하였다. 이식 전 및 이식1년 후에 요추골 및 대퇴골 골밀도를 측정할 수 있었던 36명의 환자들을 대상으로 냉동 보관되어 있던 혈청을 이용하여 IGF-I, FGF-2 및 M-CSF를 시기별로 측정하였으며 이들 성장인자와 골교체표지자의 변화 및 골밀도 변화 사이의 상관관계를 확인하였다. 결과: 골흡수 표지자인 혈청 ICTP는 이식 전에 비해 이식 후 4주까지 점차 의의 있게 증가하다가 이후 6개월까지 더욱 증가한 후 감소하였다. 골형성 표지자인 osteocalcin은 이식 후 3주까지는 점차 감소하다가 이후 증가하여 이식 후 3개월 및 6개월에 기저치보다 통계적으로 유의하게 증가한 후 감소하였다. 혈청 IGF-I과 FGF-2는 각각 이식 후 3주 및 1주까지 의미있게 감소하다가 이후 증가하였으며 혈청 M-CSF는 이식 후 1주째에 기저치에 비해 의미 있게 증가하였다가 이후 기저치로 회복되었다. 이식 1년 후 평균 요추부 골밀도는 5.2% 감소하였고 평균 근위대퇴골 골밀도는 11.6% 감소하였다. 이식 전 및 이식 후 3주에 측정한 IGF-I과 같은 시기에 측정한 오스테오칼신 사이에 유의한 상관관계가 관찰되었으며 이식 후 3주째의 M-CSF와 골흡수표지자인 M-CSF 사이에서 의미 있는 양의 상관관계를 관찰할 수 있었다. 이식 후 3주 및 3개월에 IGF-I이 낮은 환자일수록 이식 1년 후 근위대퇴골에서의 골소실이 많은 것으로 분석되었다. 결론: 조혈모세포이식 후 발생하는 골소실에는 기존에 알려진 기저질환의 영향, 성호르몬의 감소, 면역억제의 투여, 골수기질세포와 조골세포의 손상 및 이식초기 사이토카인의 변화이외에도 골성장인자가 관련이 있음을 확인하였고, 이는 이식 후 발생되는 골량소실에 중요한 역할을 할 것이라고 사료된다. Background: A loss of bone mass is usually detected after a bone marrow transplantation (BMT), especially during the early post-transplant period. We recently reported that enhanced bone resorption following a BMT was related to both the steroid dose and the increase in IL-6. We also suggested damage to the marrow stromal microenvironment, by myoablation, partly explains the impaired bone formation following a BMT. It is well known that some growth factor play important role in bone growth and osteogenesis. However, the pathogenetic role of bone growth factors in post-BMT bone loss is unknown and data on the changes in the growth factors, in accordance with bone turnover markers and bone mineral density (BMD) changes are scarce. We investigated changes in bone growth factors such as IGF-I (Insulin-like growth factor-I), fibroblast growth factor-2 (FGF-2) and Macrophage colony stimulating factor (M-CSF), during the post-BMT period, and assessed whether the growth factor changes influenced the bone turnover and post-BMT bone loss. The present study is the first prospective study to describe the changes in bone growth factors following a BMT. Methods: We prospectively investigated 110 patients undergoing a BMT, and analyzed 36 patients (32.4±1.3 years, 17 men and 19 women) whose BMDs were measured before, and 1 year after, the BMT. The serum biochemical markers of bone turnover were measured before, 1, 2, 3 and 4 weeks, 3 and 6 months, and 1 year, after the BMT. The serum, FGF-2, IGF-I and M-CSF levels were measured before and 1 and 3 weeks, and 3 months after the BMT. The correlation between the changes of growth factors and various bone parameters was analyzed. Results: The mean bone losses in the lumbar spine and total proximal femur, calculated as the percentage change from the baseline to the level at 1 year, were 5.2(p<0.05) and 11.6%(p<0.01), respectively. the serum type I carboxyterminal telopeptide(ICTP), a bone resorption marker, increased progressively until 6 months after the BMT, but thereafter decreased, to the base value after 1 year. Serum osteocalcin, a bone formation marker, decreased progressively, until 3 weeks after the BMT but then increased transiently, and finally returned to the base level at 1 year. The serum IGF-I and FGF-2 also decreased progressively until 3 weeks 1 week after the BMT, respectively, then increased to the base values at 3 months. The serum M-CSF increased briskly at 1 week post-BMT, then decreased to the base level. There were positive correlations between the percentage changes from the baseline proximal femur BMD and the IGF-I levels 3 weeks and 3 months (r=0.52, p<0.01, r=0.41, p<0.05) post BMT. A significant correlation was found between the IGF-I and osteocalcin levels pre-BMT, and 3 weeks after the BMT. Another positive correlation was found between the M-CSF and the ICTP levels at 3 weeks post BMT (r=0.54, p<0.05). Conclusion: In conclusion, there were significant changes in the serum IGF-I, FGF-2 and M-CSF levels in the immediate post-BMT period, which were related to a decrease in bone formation and loss in the proximal femoral BMD during the year following the BMT (J Kor Soc Endocrinol 17:664∼674, 2002).
Baek, Je-Hyun,Yang, Won Suk,Lee, Cheolju,Yu, Myeong-Hee American Society for Biochemistry and Molecular Bi 2009 Molecular and Cellular Proteomics Vol.8 No.5
<P>The native state of alpha(1)-antitrypsin (alpha(1)AT), a member of the serine protease inhibitor (serpin) family, is considered a kinetically trapped folding intermediate that converts to a more stable form upon complex formation with a target protease. Although previous structural and mutational studies of alpha(1)AT revealed the structural basis of the native strain and the kinetic trap, the mechanism of how the native molecule overcomes the kinetic barrier to reach the final stable conformation during complex formation remains unknown. We hypothesized that during complex formation, a substantial portion of the molecule undergoes unfolding, which we dubbed functional unfolding. Hydrogen-deuterium exchange coupled with ESI-MS was used to analyze this serpin in three forms: native, complexing, and complexed with bovine beta-trypsin. Comparing the deuterium content at the corresponding regions of these three samples, we probed the unfolding of alpha(1)AT during complex formation. A substantial portion of the alpha(1)AT molecule unfolded transiently during complex formation, including not only the regions expected from previous structural studies, such as the reactive site loop, helix F, and the following loop, but also regions not predicted previously, such as helix A, strand 6 of beta-sheet B, and the N terminus. Such unfolding of the native interactions may elevate the free energy level of the kinetically trapped native serpin sufficiently to cross the transition state during complex formation. In the current study, we provide evidence that protein unfolding has to accompany functional execution of the protein molecule.</P>
Probing the local conformational change of α<sub>1</sub>-antitrypsin
Baek, Je-Hyun,Im, Hana,Kang, Un-Beom,Seong, Ki Moon,Lee, Cheolju,Kim, Joon,Yu, Myeong-Hee Wiley (John WileySons) 2007 Protein science Vol.16 No.9
<P>The native form of serpins (serine protease inhibitors) is a metastable conformation, which converts into a more stable form upon complex formation with a target protease. It has been suggested that movement of helix-F (hF) and the following loop connecting to strand 3 of beta-sheet A (thFs3A) is critical for such conformational change. Despite many speculations inferred from analysis of the serpin structure itself, direct experimental evidence for the mobilization of hF/thFs3A during the inhibition process is lacking. To probe the mechanistic role of hF and thFs3A during protease inhibition, a disulfide bond was engineered in alpha(1)-antitrypsin, which would lock the displacement of thFs3A from beta-sheet A. We measured the inhibitory activity of each disulfide-locked mutant and its heat stability against loop-sheet polymerization. Presence of a disulfide between thFs3A and s5A but not between thFs3A and s3A caused loss of the inhibitory activity, suggesting that displacement of hF/thFs3A from strand 5A but not from strand 3A is required during the inhibition process. While showing little influence on the inhibitory activity, the disulfide between thFs3A and s3A retarded loop-sheet polymerization significantly. This successful protein engineering of alpha(1)-antitrypsin is expected to be of value in clinical applications. Based on our current studies, we propose that the reactive-site loop of a serpin glides through between s5A and thFs3A for the full insertion into beta-sheet A while a substantial portion of the interactions between hF and s3A is kept intact.</P>
Baek, Je-Hyun,Han, Beom-Ku,Jo, Do-Hyun Korean Society for Biochemistry and Molecular Biol 2001 Journal of biochemistry and molecular biology Vol.34 No.4
The uneven distribution of acidic and basic chitinases in different parts of rice seed, and also the characterization of hull-specific chitinases, are reported here. After extraction of chitinases from polished rice, bran, and rice hulls, the chitinases were separated into acidic and basic fractions, according to their behavior on an anion exchanger column. Both fractions from different parts of rice seed showed characteristic activity bands on SDS-PAGE that contained 0.01% glycol chitin. The basic chitinases from rice hulls were further purified using chitin affinity chromatography. The chitinase, specific to rice hulls (RHBC), was 88-fold purified with a 1.3% yield. RHBC has an apparent molecular weight of 22.2 kDa on SDS-PAGE. The optimal pH and temperature were 4.0 and $35^{\circ}C$, respectively. With [$^3H$]chitin as a substrate, RHBC has $V_{max}$ of 13.51 mg/mg protein/hr and $K_m$ of 1.36 mg/ml. This enzyme was an endochitinase devoid of ${\beta}$-1,3-glucanase, lysozyme, and chitosanase activities.
Baek, Je-Hyun,Lee, Gong-Hee,Myung, Hwan-Joo The Society of Air-Conditioning and Refrigerating 2004 International Journal Of Air-Conditioning and Refr Vol.12 No.1
An experimental analysis using three-dimensional Laser Doppler Velocimetry(LDV) measurement and computational analysis using the Reynolds stress model in FLUENT are conducted to give a clear understanding of the effect of blade loading on the structure of tip leakage flow in a forward-swept axial-flow fan operating at the maximum efficiency condition ($\Phi$=0.25) and two off-design conditions ($\Phi$=0.21 and 0.30). As the blade loading increases, the onset position of the rolling-up of tip leakage flow moves upstream and the trajectory of tip leakage vortex center is more inclined toward the circumferential direction. Because the casing boundary layer becomes thicker and the mixing between the through-flow and the leakage jet with the different flow direction is enforced, the streamwise vorticity decays more fast with the blade loading increasing. A distinct tip leakage vortex is observed downstream of the blade trailing edge at $\Phi$=0.30, but it is not observed at $\Phi$=0.21 and 0.25.