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排序方式: 共有183条查询结果,搜索用时 15 毫秒
31.
Ruenn Chai Lai Fatih Arslan May May Lee Newman Siu Kwan Sze Andre Choo Tian Sheng Chen Manuel Salto-Tellez Leo Timmers Chuen Neng Lee Reida Menshawe El Oakley Gerard Pasterkamp Dominique P.V. de Kleijn Sai Kiang Lim 《Stem cell research》2010,4(3):214-222
Human ESC-derived mesenchymal stem cell (MSC)-conditioned medium (CM) was previously shown to mediate cardioprotection during myocardial ischemia/reperfusion injury through large complexes of 50–100 nm. Here we show that these MSCs secreted 50- to 100-nm particles. These particles could be visualized by electron microscopy and were shown to be phospholipid vesicles consisting of cholesterol, sphingomyelin, and phosphatidylcholine. They contained coimmunoprecipitating exosome-associated proteins, e.g., CD81, CD9, and Alix. These particles were purified as a homogeneous population of particles with a hydrodynamic radius of 55–65 nm by size-exclusion fractionation on a HPLC. Together these observations indicated that these particles are exosomes. These purified exosomes reduced infarct size in a mouse model of myocardial ischemia/reperfusion injury. Therefore, MSC mediated its cardioprotective paracrine effect by secreting exosomes. This novel role of exosomes highlights a new perspective into intercellular mediation of tissue injury and repair, and engenders novel approaches to the development of biologics for tissue repair. 相似文献
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动物行为和生理活动的适应性调节是应对食物资源变化的主要策略。为探讨禁食和重喂食对大绒鼠体重、产热和血清瘦素的影响,测定了禁食和重喂食条件下大绒鼠的体重、体脂重量、静止代谢率、身体组成、血清瘦素含量以及禁食后重喂食期间的摄食量。结果显示:禁食导致大绒鼠体重、体脂重量和静止代谢率显著下降,重喂食后体重和静止代谢率能够恢复到对照组水平,而体脂重量却不能恢复。禁食12 h 后血清瘦素含量快速下降,重喂食后未能恢复到对照水平。此外,大绒鼠在禁食后重喂食期间摄食量没有补偿性增加,血清瘦素含量与体脂重量呈正相关关系。这些结果很可能反映出大绒鼠能调节自身生理状况以适应短期的能量缺乏,主要通过降低体重、血清瘦素含量和代谢活性器官重量以减少能量消耗。禁食后重喂食时大绒鼠没有摄食过量。血清瘦素的下降早于体重和体脂的下降。 相似文献
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早籼稻米垩白形成中的生理生化变化特性 总被引:13,自引:0,他引:13
以早籼多垩白品种泸红早1号、浙733和少垩白品种中优早3号、舟优903及中籼中引85为材料,在自然高温条件下对水稻灌浆过程中胚乳内含物质(如淀粉、可溶性糖等)和酶(淀粉磷酸化酶、Q酶)活性的连续变化进行测定。结果表明,不同垩白度品种其胚乳内部物质增长的时间进程和酶活性的变化存在差异,由此造成灌浆动态明显不同,并导致垩白形成的差异。 相似文献
35.
Yu‐Kuang Liao Maël Brossard Dan‐Hua Hsieh Tzu‐Neng Lin Martin D. B. Charlton Shun‐Jen Cheng Chyong‐Hua Chen Ji‐Lin Shen Lung‐Teng Cheng Tung‐Po Hsieh Fang‐I Lai Shou‐Yi Kuo Hao‐Chung Kuo Pavlos G. Savvidis Pavlos G. Lagoudakis 《Liver Transplantation》2015,5(2)
A novel scheme for hybridizing inkjet‐printed thin film Cu(In,Ga)Se2 (CIGS) solar cells with self‐assembled clusters of nanocrystal quantum dots (NQDs), which provides a 10.9% relative enhancement of the photon conversion efficiency (PCE), is demonstrated. A non‐uniform layer of NQD aggregates is deposited between the transparent conductive oxide and a CdS/CIGS p‐n junction using low cost pulsed‐spray deposition. Hybridization significantly improves the external quantum efficiency of the hybrid devices in the absorption range of the NQDs and in the red to near‐IR parts of the spectrum. The low wavelength response enhancement is found to be induced by luminescent down‐shifting (LDS) from the NQD layer, while the increase at longer wavelengths is attributed to internal scattering from NQD aggregates. LDS is demonstrated using time‐resolved spectroscopy, and the morphology of the NQD layer is investigated in fluorescence microscopy and cross‐sectional transmission electron microscopy. The influence of the NQD dose on the PCE of the hybrid devices is investigated and an optimum value is obtained. The low costs and limited material consumptions associated with pulsed‐spray deposition make these flexible hybrid devices promising candidates to help push thin‐film photovoltaic technology towards grid parity. 相似文献
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【目的】为揭示芥菜型油菜及芸薹属作物每角籽粒数形成的分子机理,提高和改良芥菜型油菜产量和育种工作奠定基础。【方法】研究以包含221个芥菜型油菜株系的重组自交系(recombinant inbred line, RIL)群体为材料,在5个环境条件下对每角籽粒数性状进行加性QTL、加性×加性上位互作及环境互作分析。【结果】(1)共检测到7个与每角籽粒数相关的加性QTL,主要分布在芥菜型油菜A02、A03、A05、A08、B02和B03等染色体上,其加性效应分布在(-11.642 4)~4.524 6之间,其中qSS2-71的加性效应和遗传率均最大,分别达到-11.642 4和14.44%,其余6个加性QTL的加性效应和遗传率均较小;(2)检测到7对影响每角籽粒数的加性×加性QTL上位互作效应及其与环境的互作效应,上位性QTL互作效应值分布在(-4.930 8)~4.193 6之间,7对上位性QTL与不同环境互作的遗传力均接近0;(3)每角籽粒数性状的广义遗传率为80.98%,狭义遗传率为30.98%。【结论】综合分析,芥菜型油菜每角籽粒数受一定环境影响,但控制该性状的加性效应受环境影响较小... 相似文献
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Michael A. Collins Neng Ung-Chhun Bhe Y. Cheng Debra Pronger 《Journal of neurochemistry》1990,55(5):1507-1514
Brain concentrations of salsolinol (SAL), a simple tetrahydroisoquinoline (sTIQ) condensation product of dopamine (DA) and acetaldehyde, are reported to increase in chow-fed rats drinking ethanol/H2O ad libitum. However, our analyses showed that rat chow contains traces of SAL and, as previously reported, appreciable 3,4-dihydroxyphenylalanine (DOPA), a sTIQ precursor. To examine the effect of consumption of ethanol in a DOPA- and SAL-free diet on endogenous sTIQs, we analyzed two brain regions and blood plasma of rats undergoing prolonged intake (3 weeks and 23 weeks) of liquid diet containing 6.6% ethanol or isocaloric carbohydrate. SAL and three other DA-related sTIQs were quantitated using capillary gas chromatography/mass spectrometry in the selected ion mode with deuterated standards. In accord with studies on ethanol/chow-fed rats, sTIQ concentrations in hypothalamus were elevated after 3 weeks of ethanol, although after 23 weeks, hypothalamic sTIQs were either unchanged or reduced (O-methylated SAL). Furthermore, sTIQ concentrations in corpus striatum and, with one exception, plasma were not altered by ethanol ingestion for either duration. (However, 23 weeks of ethanol intake significantly reduced the striatal concentrations of DA and its acid metabolite, presumably reflecting neurotoxicity.) Reasoning that DOPA in diet might underlie the reported ethanol-dependent increases in striatal sTIQs, we found that L-DOPA supplementation (500 micrograms/rat/day) of EtOH/liquid diet-fed rats for 13 weeks tended to increase striatal SAL. Overall, the data indicate that elevations in endogenous sTIQ concentrations due to prolonged ethanol intake depend on the brain region, duration of intake, and even associated dietary constituents. In that regard, the higher striatal SAL concentrations in rats drinking ethanol ad libitum could have been facilitated by DOPA and perhaps SAL consumed in lab chow. 相似文献
40.
报道了产自云南屏边的中国蜘蛛抱蛋属一新记录种——垂花蜘蛛抱蛋(Aspidistra nutans Aver.&Tillich)。该种是2017年发表的新种,采集于越南西北部地区,原文缺少果实描述,现补充描述该种果的形态特征。本种与辐花蜘蛛抱蛋(A.subrotata Y.Wan&C.C.Huang)在形态上相近,但其叶片中脉和侧脉明显突出,花梗近先端向下弯曲,长0.8~4.5 cm,花下垂,常贴生于地面,花被紫褐色,常平展,柱头纯白色(后者叶脉凹陷,花梗直立,长约5 mm,花斜向上开,花被暗紫色,内面具有小乳突,柱头白色带紫色斑点)而显著有别于后者。 相似文献