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21.
Edmund H. Frank Boyce W. Burge Boleslaw H. Liwnicz Linda J. Lotspeich Jocelyn C. White Steven L. Wechsler Frank H. Mayfield Jeffrey T. Keller 《Experimental cell research》1983,146(2):371-376
Cells from cranial and spinal arachnoid membranes of humans were grown in culture. Their growth characteristics, morphology and details of their cytoskeletal composition are described. Arachnoid membranes, obtained at autopsy, were finely minced and incubated in tissue culture medium. Monolayers of cells of homogeneous morphology grew from these tissue fragments. The cells were flat and polygonal. They divided slowly to form non-overlapping monolayers of low cell density. Electron microscopic examination of cultured arachnoid cells revealed numerous desmosome-like tight junctions and abundant intermediate filaments (tonofilaments). Both morphological features are characteristic of arachnoid cells in situ, but not of cells in the fibroblast-rich dura mater. Immunofluorescence microscopy with monoclonal antibodies demonstrated cytokeratin in the cytoplasm of primary cultures of arachnoid cells. Thus we demonstrated that these cultured cells retained certain of the specific differentiated properties of arachnoid cells in situ and that they are not fibroblasts (which lack tight junctions and cytokeratins). To our knowledge, there have been no previous reports of in vitro growth of arachnoid cells. This in vitro model should be useful in studying the response of arachnoid cells to a variety of substances thought to be involved in the chronic inflammatory condition of the meninges known as arachnoiditis. 相似文献
22.
Ricardo Gonzalez-Mendez David Wemmer George Hahn Norma Wade-Jardetzky Oleg Jardetzky 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,720(3):274-280
A continuous-flow NMR culture system for mammalian cells has been developed on which 31P-NMR experiments under complete and strictly physiologic conditions have been performed. Observations on the response of the cellular metabolism to stresses such as starvation, low temperature and changes in environmental pH monitored by 31P-NMR are reported. The response of the intracellular pH relative to the external pH of the growth medium is studied. We find that under the experimental conditions used there exists a ΔpH varying between less than 0.2 and more than 0.6 pH units. These results are compatible with those obtained using other techniques. 相似文献
23.
Emmanuelle Fontoura José Darival Ferreira Jamile Bubadué Ana Maria Ribeiro Leonardo Kerber 《Journal of morphology》2020,281(10):1223-1240
A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology. 相似文献
24.
Ricardo Godoy Christopher P. A. Bennett 《Human ecology: an interdisciplinary journal》1991,19(1):83-98
This article contains a comparison of the profits of cultivating modern and traditional varieties of coconuts as a monocrop and as an intercrop, in ideal and in average growing conditions, with good and with average management. We carry out the analysis from a private (financial) and from a national (economic) perspective. The results show that intercropping generates more income than monocropping. In the conclusion we discuss why development organizations and Third World countries encourage monocropping. 相似文献
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Josef B. Keller 《Plant Systematics and Evolution》1872,22(10):335-337
Ohne Zusammenfassung 相似文献
28.
In the sequence of superorders Rutiflorae-Santaliflorae-Araliiflorae-Asteriflorae an increase in the mean oxidation state for each series of Cn-polyacetylenes and an extension in the range of the carbon atoms of these polyacetylenes in the direction of smaller numbers are observed. These trends of polyacetylene evolution also seem to be operative at lower hierarchic levels in the family Asteraceae. 相似文献
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Several previously unavailable parameters of adenosine 3':5'-monophosphate have been determined. The molar extinction coefficient at pH 7.0 is 1.38 X 10(-4), the aqueous solubility at pH 7.0 is 0.0236 M and the diffusion coefficient is 4.44 X 10(-6) cm2/s. 相似文献