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SEARCH FOR THE RETURN OF ACTIVITY IN ACTIVE ASTEROID 176P/LINEAR
Hsieh, Henry H.,Denneau, Larry,Fitzsimmons, Alan,Hainaut, Olivier R.,Ishiguro, Masateru,Jedicke, Robert,Kaluna, Heather M.,Keane, Jacqueline V.,Kleyna, Jan,Lacerda, Pedro,MacLennan, Eric M.,Meech, Kar American Institute of Physics 2014 The Astronomical journal Vol.147 No.4
<P>We present the results of a search for the reactivation of active asteroid 176P/LINEAR during its 2011 perihelion passage using deep optical observations obtained before, during, and after that perihelion passage. Deep composite images of 176P constructed from data obtained between 2011 June and 2011 December show no visible signs of activity, while photometric measurements of the object during this period also show no significant brightness enhancements similar to that observed for 176P between 2005 November and 2005 December when it was previously observed to be active. An azimuthal search for dust emission likewise reveals no evidence for directed emission (i.e., a tail, as was previously observed for 176P), while a one-dimensional surface brightness profile analysis shows no indication of a spherically symmetric coma at any time in 2011. We conclude that 176P did not in fact exhibit activity in 2011, at least not on the level on which it exhibited activity in 2005, and suggest that this could be due to the devolatization or mantling of the active site responsible for its activity in 2005.</P>
Lovastatin이 골격근 세포의 지방산 산화에 미치는 영향
김동림 ( Dong Lim Kim ),송기호 ( Kee Ho Song ),김숙경 ( Suk Kyeong Kim ),김해림 ( Hae Rim Kim ),( Theodore P. Ciaraldi ),( Robert R. Henry ) 대한내과학회 2007 대한내과학회지 Vol.72 No.6
목적: Statin이 혈당을 감소시키고 인슐린 저항성을 개선시킨다고 보고되었다. 본 연구는 statin이 인슐린 저항성의 주 조직인 골격근에서 지방산의 산화에 어떤 영향을 미치는지를 알아보고자 하였다. 방법: 정상 혈당군 7명과 제2형 당뇨병 환자 7명에서 근육 생검으로 골격근 조직을 얻었다. 골격근 세포를 배양하여 분화 후 lovastatin (0, 20 μM)을 배지에 첨가하고 2일 후 [9,10-3H] palmitate 와 [8-3H] octanoate를 이용하여 지방산 산화를 측정하였다. 유리 지방산 산화를 조절하는 기전을 알아보고자 AMPK와 ACC 인산화를 관찰하였다. 결과: Lovastatin 처리 후 대조군과 비교하여 palmitate의 산화 및 (44.2±12.1 nmol/mg protein/3h, 271.2±32.7% 증가 vs 15.5±3.0 nmol/mg protein/3h, p<0.01) octanoate의 산화가 유의하게 증가하였다(10.0±4.6 nmol/mg protein/3h, 158.3±21.9% 증가 vs 5.0±1.4 nmol/mg protein/3h, p<0.05). 이런 반응은 정상 혈당군과 제2형 당뇨병 환자의 골격근 세포 모두에서 유사하였다. Lovastatin 처리 후 AMPK의 인산화는 관찰되지 않았지만 AMPK 단백은 감소하였다(73.6±6.2% of control, p<0.01). ACC의 인산화는 통계적으로 유의하게 증가하였다(149.5±20.6% of control, p<0.05). 결론: ACC 인산화를 통한 지방산 산화의 증가가 lovastatin이 골격근에 침착된 지방 농도를 감소 시키고 인슐린 저항성을 호전시킬 것으로 생각된다. Background: Recent clinical studies have suggested that statins improve insulin resistance and glucose metabolism in the skeletal muscle of diabetic patients. To evaluate a possible component of this action, we measured free fatty acid oxidation in cultured human skeletal muscle cells (HSMC). Methods: Seven normal controls and 7 type 2 diabetic patients underwent quadriceps muscle biopsy. The HSMCs (n=14) were treated with or without lovastatin (Lova, 20 μM) for 2 days, and the free fatty acid (FFA) oxidation was measured. Results: Lova increased the oxidation of the long-chain FA palmitate to 271.2±32.7% of the control (p<0.01). Oxidation of the medium chain FA octanoate also increased after treatment of Lova (158.3±21.9%, p<0.05). One pathway of regulation of FFA is through AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation. Following Lova treatment, AMPK phosphorylation did not show a significant change while the total protein expression of AMPK was decreased (73.6±6.2% of the control, p<0.01). Lova treatment significantly increased ACC phosphorylation (149.5±20.6% of the control, p<0.05). Conclusion: Lova increased FFA oxidation by increasing the ACC phosphorylation in human skeletal muscle cells. Stimulation of skeletal muscle FFA oxidation may be one mechanism by which statins act to lower intramyocellular triglyceride and improve insulin action on glucose metabolism. (Korean J Med 72:600-606, 2007)