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1.
The sequential cytological events of the regeneration process, after partial excision of the gastrocnemius muscle in the rat, were followed by light and electron microscopy. During the first 2 days after injury leukocytes and macrophages infiltrate into the traumatized area. Myogenic regeneration is then characterized by mainly two repair mechanisms. Mononucleated cells, that populate the excised area, most probably fuse together to give rise to newly formed multinucleated myotubes that further develop to striated myofibers. Another mechanism involves the repair of injured muscle fibers by the possible fusion of mononucleated cells with their necrotic cut ends. Consequently, by addition of nuclei and new muscular material, sarcoplasmic outgrowths from the injured fibers are formed. It is concluded that mainly two repair mechanisms are involved in the regeneration process following partial excision of a muscle: addition of new muscle fibers in a process similar to that of embryonic myogenesis and also meristic growth from the injured fibers. 相似文献
2.
Chromosomal RNA: an artifact of preparation? 总被引:2,自引:0,他引:2
3.
W. O. van der Knaap Jacqueline F. N. van Leeuwen Tomasz Goslar Robert Krisai Willy Tinner 《Vegetation History and Archaeobotany》2012,21(1):37-60
Three mires and a small lake in the Swiss and Austrian Alps were studied palynologically at high resolution, covering the
last 1,000, 400, 50 and 1,200 years, respectively. Methodological lessons include: (1) Sub-decadal resolution in upper, little-decomposed
peat layers reveals recurrent marked fluctuations in both percentages and influx of regional tree-pollen types, reflecting
variations in pollen production rather than in plant-population sizes. (2) Intermittent, single-spectrum pollen maxima in
samples of sub-decadal resolution indicate pollen transport in clumps. This type of pollen transport may remain unrecognized
in sections with lower sampling resolution, which may then lead to inappropriate interpretation in terms of plant-population
sizes. (3) The detection of short-lived phases of human impact in decomposed peat requires sampling intervals as close as
0.2 cm. (4) PAR (pollen influx) may reflect vegetation dynamics more faithfully than percentages. Reliable PAR, however, is
difficult to achieve in Alpine mires due to past human impact on peat growth, even when complex depth–age modelling techniques
are used. Critical comparison of PAR with percentages is therefore essential. (5) Careful consideration of spatial scales
in pollen signals (local–regional and subdivisions) is essential for a realistic palaeo-ecological interpretation. Results
in terms of past human impact on vegetation are summarized as follows: (1) Trends in pollen types reflecting regional human
action are in general agreement with earlier findings for the western Swiss Alps, allowing for regional differences. (2) All
mires in the Alps investigated here and in an earlier study experienced human impact during the last millennium. The studied
small lake, lying in sub-alpine pasture, records forest dynamics at a lower elevation since a.d. 800. 相似文献
4.
ACTH stimulation of adenyl cyclase in adrenal homogenates 总被引:6,自引:0,他引:6
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Expression patterns of the T antigen and the cryptic T antigen in rat fetuses: detection with the lectin amaranthin 总被引:4,自引:0,他引:4
T Sata C Zuber S J Rinderle I J Goldstein J Roth 《The journal of histochemistry and cytochemistry》1990,38(6):763-774
The lectin amaranthin, purified from the seeds of Amaranthus caudatus, has been shown to react specifically with the Gal beta 1,3GalNAc-alpha and the NeuAc alpha 2,3Gal beta 1,3GalNAc-alpha sequence which represent the T antigen and the cryptic T antigen, respectively. We report here the development of labeling techniques that apply amaranthin to stain paraffin sections from rat fetuses. Amaranthin staining was inhibited by pre-incubation of lectin-gold complexes with 10 mM Gal beta 1,3GalNAc-alpha-O-benzyl (synthetic T antigen) or 10 mM Gal beta 1,3GalNAc-alpha-O-aminophenylethyl-human serum albumin (T antigen neoglycoprotein), asialoglycophorin, asialofetuin, and asialomucin. The beta-elimination reaction also abolished the lectin staining demonstrating specificity for O-glycosidically linked structures. A comparison with monoclonal anti-T antigen antibody immunostaining demonstrated that amaranthin detects the T antigen and its cryptic form in tissue sections. Application of the galactose oxidase-Schiff sequence abolished amaranthin (and anti-T antibody) binding to the T antigen but not to its cryptic form, and therefore permitted their differentiation in tissue sections. Histochemical evidence was obtained indicating that amaranthin is a more specific anti-T reagent than peanut lectin. Data are presented that show the differential expression of the T antigen and the cryptic T antigen in organs and cells of rat fetuses late in gestation. Therefore, amaranthin can be used for histochemical detection of the T antigen and the cryptic T antigen, and facilitates discrimination between them. 相似文献
8.
New series of lipoxins isolated from human eosinophils 总被引:1,自引:0,他引:1
Granulocytes from human eosinophilic donors were incubated with arachidonic acid or 15-hydroxyeicosatetraenoic acid (15-HETE) and stimulated with the ionophore A23187. The eicosanoids were extracted with reversed-phase cartridges and subjected to RP-HPLC analysis. When extracts from eosinophil-enriched populations were analysed and compared with extracts from human neutrophils, three additional peaks were detected which coeluted with 15-hydroxy-delta 13-trans-15H derivatives of leukotriene C4, D4 and E4 in different HPLC systems. The recorded absorbance spectra of the eluted compounds and the standards were identical and showed a maximum at 307 nm which is characteristic for a conjugated tetraene system with a bathochromic shift by the sulfur moiety in alpha-position to the tetraene system. The compound which coeluted with the 15-hydroxy-LTC4 standard was treated with gamma-glutamyltransferase and converted to the corresponding leukotriene D4 derivative. The results indicate that interaction between the 5- and 15-lipoxygenase pathways leads to the formation of a new series of arachidonic acid metabolites in human eosinophils. Since the biosynthetic route is similar to that of lipoxin A4 and lipoxin B4, we suggest the trivial names lipoxin C4, D4 and E4. 相似文献
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