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排序方式: 共有847条查询结果,搜索用时 46 毫秒
1.
Stefano Carenini Dirk Montag Harold Cremer Melitta Schachner Rudolf Martini 《Cell and tissue research》1996,287(1):3-9
We have previously shown that mice deficient in the gene for the myelin-associated glycoprotein (MAG) develop normal myelin
in the peripheral nerves, but show axon and myelin degeneration at eight months of age, suggesting that MAG is involved in
the maintenance of axon-Schwann cell integrity. The search for molecules that might replace MAG during myelination revealed
an overexpression of the neural cell adhesion molecule (N-CAM) at those aspects where MAG is detectable in wild type mice.
To test whether N-CAM might compensate for MAG during myelination in MAG-deficient mice, double mutants deficient in both
MAG and N-CAM (MAG−/N-CAM−mice) were generated by cross-breeding the single mutants. Whereas alterations of myelin development were not detectable in
either of the single or double mutants, degeneration of myelin and axons occurred approximately 4 weeks earlier in MAG−/N-CAM−than in MAG−mutants. Furthermore, at 8 weeks of age, single fiber preparation and electron microscopy revealed that the number of profiles
indicative of degeneration was substantially increased in MAG−/N-CAM−mutants when compared to MAG−mice. These data suggest that in MAG-deficient mice N-CAM does not compensate for MAG in myelin formation but partially substitutes
for it in the maintenance of axon-myelin integrity.
Received: 20 May 1996 / Accepted: 19 July 1996 相似文献
2.
R Martini 《Tissue & cell》1989,21(5):639-645
Data from light- and electronimmunocytochemistry gave evidence that the antibodies to the mammalian adhesion molecule J1/tenascin and its carbohydrate structure L2/HNK-1 react with immunoreactive structures present in the inner and outer receptor lymph cavities of antennal sensilla of the honey bee. Immunoreactivity was additionally present in the cytoplasm of the enveloping cells surrounding the receptor lymph cavities. Cell contacts between enveloping cells and between dendrites and enveloping cells were never observed to be antigen positive. 相似文献
3.
The imaginal pore plates of Hymenoptera apocrita so far examined embody five or six envelope cells respectively. In early developmental stages, however, supernumerary envelope cells have been found. The results are discussed in the context of cell death as a developmental phenomenon. 相似文献
4.
The complete coding sequence for human glucose-6-phosphate-dehydrogenase (G6PD) was inserted downstream from the tac promoter of a plasmid, pJF118EH, which also carries the lacIq repressor gene. When Escherichia coli strains (that are unable to grow on glucose due to the absence of functional zwf (G6PD-) and pgi genes) were transformed with this plasmid (pAC1), they were able to grow on glucose as sole carbon source. The rate of growth on glucose was faster in the presence of the inducer of the tac promoter, isopropyl-beta-D-thiogalactopyranoside (IPTG). Extracts of the transformed cells contained a G6PD activity that was not detectable in the parental strains and that was inducible by IPTG. The G6PD activities from normal E. coli and from pAC1-transformed cells comigrated with human G6PD when subjected to electrophoresis on agarose gels. However, when denatured, the G6PD produced by pAC1 was, like the human enzyme, distinguishable from the E. coli-encoded enzyme on the basis of its immunoreactivity with antibody specific for human G6PD. Therefore, human G6PD can be expressed in E. coli and can function to complement the bacterial enzyme deficiency. 相似文献
5.
6.
M Veini O E Tsitsiloni S M Martini A A Haritos 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(4):775-781
Soluble esterases in tissues of endodermic origin and of various developmental ages of Gallus gallus were analysed by polyacrylamide slab gel electrophoresis and characterized as carboxylesterases, acetylesterases and cholinesterases. Esterase bands were observed from day 9 in the liver and from day 6 in stomach, intestine and yolk sac. The electrophoretic profiles became more complex after hatching with concomitant increase in the staining intensity. On isoelectric focusing of liver extracts only a major form with pI 5.4 was observed. An eserine sensitive band designated EL-1 was found to be tissue (liver) and age (upon hatching) specific. EL-1-like isozymes were also observed in other species of the Galliformes order. 相似文献
7.
U Bonuccelli A Nuti P Del Dotto P Piccini C Martini G Giannaccini A Lucacchini A Muratorio 《Life sciences》1991,48(12):1185-1190
Peripheral benzodiazepine (BDZ) receptors are located in a variety of tissues, including platelets, in the nuclear and/or mitochondrial membranes. We studied the density of peripheral BDZ receptors in platelets of 10 de novo Parkinson's disease (PD) patients, 18 PD patients treated with a levodopa/carbidopa combination, and in 15 healthy subjects matched for sex and age. The binding assay was conducted using [3H]PK 11195, a specific ligand for peripheral BDZ receptors. A significant decrease in the density of [3H]PK 11195 binding sites has been observed in PD patients with respect to controls (p less than 0.01), but not between de novo and treated PD patients. No correlation has been found between the decrease in density of [3H]PK 11195 binding sites in platelets and either the duration or severity of PD. Peripheral BDZ receptors are implicated in the regulation of mitochondrial respiratory function. Thus, their decrease in PD might parallel the abnormalities in mitochondrial function recently found in this neurologic disease. 相似文献
8.
The proportion of leaves damaged by specialist guilds such as miners and sap-feeders decreased at locations with higher species richness and at higher elevation in four subtropical forest seedling communities in south China. The effect of elevation was stronger in winter. Patterns of the generalist guild chewers were weaker. 相似文献
9.
In this paper, we propose an adversary model to facilitate forensic investigations of mobile devices (e.g. Android, iOS and Windows smartphones) that can be readily adapted to the latest mobile device technologies. This is essential given the ongoing and rapidly changing nature of mobile device technologies. An integral principle and significant constraint upon forensic practitioners is that of forensic soundness. Our adversary model specifically considers and integrates the constraints of forensic soundness on the adversary, in our case, a forensic practitioner. One construction of the adversary model is an evidence collection and analysis methodology for Android devices. Using the methodology with six popular cloud apps, we were successful in extracting various information of forensic interest in both the external and internal storage of the mobile device. 相似文献
10.
The use of affinity chromatography as means of isolating/ purifying proteins which have an affinity for benzodiazepine is described. Three such drugs are employed: chlorazepate, clonazepam and delorazepam. The results presented in this paper indicate that the proposed technique only works for chlorazepate and delorazepam. In fact these benzodiazepine–Sepharose derivatives are able to retain specifically proteins from human serum and rat kidney, lung, skeletal muscle and brain. 相似文献