排序方式: 共有49条查询结果,搜索用时 15 毫秒
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Kramer J Böhrnsen F Lindner U Behrens P Schlenke P Rohwedel J 《Cellular and molecular life sciences : CMLS》2006,63(5):616-626
Microfracture of subchondral bone results in intrinsic repair of cartilage defects. Stem or progenitor cells from bone marrow
have been proposed to be involved in this regenerative process. Here, we demonstrate for the first time that mesenchymal stem
(MS) cells can in fact be recovered from matrix material saturated with cells from bone marrow after microfracture. This also
introduces a new technique for MS cell isolation during arthroscopic treatment. MS cells were phenotyped using specific cell
surface antibodies. Differentiation of the MS cells into the adipogenic, chondrogenic and osteogenic lineage could be demonstrated
by cultivation of MS cells as a monolayer, as micromass bodies or mesenchymal microspheres. This study demonstrates that MS
cells can be attracted to a cartilage defect by guidance of a collagenous matrix after perforating subchondral bone. Protocols
for application of MS cells in restoration of cartilage tissue include an initial invasive biopsy to obtain the MS cells and
time-wasting in vitro proliferation and possibly differentiation of the cells before implantation. The new technique already includes attraction
of MS cells to sites of cartilage defects and therefore may overcome the necessity of in vitro proliferation and differentiation of MS cells prior to transplantation.
Received 3 November 2005; received after revision 15 December 2005; accepted 4 January 2006 相似文献
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Replicatable RNA reporters 总被引:10,自引:0,他引:10
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<正> This paper studies an initial-boundary-value problem (IBVP) of the Korteweg-de Vriesequation posed on a finite interval with general nonhomogeneous boundary conditions.Using thestrong Kato smoothing property of the associated linear problem,the IBVP is shown to be locallywell-posed in the space H~s(0,1) for any s≥0 via the contraction mapping principle. 相似文献
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Evolution of genetic mechanisms controlling petal development. 总被引:21,自引:0,他引:21
Molecular genetic studies in Arabidopsis thaliana and other higher-eudicot flowering plants have led to the development of the 'ABC' model of the determination of organ identity in flowers, in which three classes of gene, A, B and C, are thought to work together to determine organ identity. According to this model, the B-class genes APETALA3 (AP3) and PISTILLATA (PI) act to specify petal and stamen identity. Here we test whether the roles of these genes are conserved throughout the angiosperms by analysing the expression of AP3 and PI orthologues in the lower eudicot subclass Ranunculidae. We show that, although expression of these orthologues in the stamens is conserved, the expression patterns in the petals differ from those found in the higher eudicots. The differences between these expression patterns suggest that the function of AP3 and PI homologues as B-class organ-identity genes is not rigidly conserved among all angiosperms. These observations have important implications for understanding the evolution of both angiosperm petals and the genetic mechanisms that control the identities of floral organs. 相似文献
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McLaughlin MA Lyne AG Lorimer DR Kramer M Faulkner AJ Manchester RN Cordes JM Camilo F Possenti A Stairs IH Hobbs G D'Amico N Burgay M O'Brien JT 《Nature》2006,439(7078):817-820
The radio sky is relatively unexplored for transient signals, although the potential of radio-transient searches is high. This was demonstrated recently by the discovery of a previously unknown type of source, varying on timescales of minutes to hours. Here we report a search for radio sources that vary on much shorter timescales. We found eleven objects characterized by single, dispersed bursts having durations between 2 and 30 ms. The average time intervals between bursts range from 4 min to 3 h with radio emission typically detectable for <1 s per day. From an analysis of the burst arrival times, we have identified periodicities in the range 0.4-7 s for ten of the eleven sources, suggesting origins in rotating neutron stars. Despite the small number of sources detected at present, their ephemeral nature implies a total Galactic population significantly exceeding that of the regularly pulsing radio pulsars. Five of the ten sources have periods >4 s, and the rate of change of the pulse period has been measured for three of them; for one source, we have inferred a high magnetic field strength of 5 x 10(13) G. This suggests that the new population is related to other classes of isolated neutron stars observed at X-ray and gamma-ray wavelengths. 相似文献
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B. Kramer 《Cellular and molecular life sciences : CMLS》1972,28(10):1195-1196
Zusammenfassung Ein synthetisches Antigonadotropin (Methallibur, I.C.I) hemmt das Sexual- und Nestbauverhalten von Sonnenbarsch-Männchen (Lepomis gibbosus). Testosteron hingegen steigert die Aggressivität, und Säuger-LH zudem noch die Sexualtendenz. Reserpin erhöht die Kampfstimmung; Chlorpromazin hemmt dagegen die Kampf- und Nestbaustimmung, nicht aber die Sexualtendenz. 相似文献
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