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排序方式: 共有1029条查询结果,搜索用时 15 毫秒
1.
Maitotoxin-Evoked γ-Aminobutyric Acid Release Is Due Not Only to the Opening of Calcium Channels 总被引:1,自引:1,他引:0
The effects of maitotoxin (MTX) on endogenous amino acid release were tested on highly purified striatal neurons differentiated in primary culture. MTX induced a large and concentration-dependent release of gamma-aminobutyric acid (GABA). This effect was abolished when experiments were performed in the absence of external Ca2+, and restored when Ca2+ ions were added after removing the MTX-containing Ca2+-free solution. MTX-induced amino acid release was not affected by 1 microM nifedipine and only slightly inhibited by 1 mM Co2+. MTX also induced a massive accumulation of 45Ca2+ in the neurons which, in contrast to the MTX-evoked GABA release, was totally blocked in the presence of 1 mM Co2+. Whereas 500 nM tetrodotoxin was without significant effect, MTX-evoked GABA release was dependent on the presence of external Na+ and sensitive to nipecotic acid, a GABA uptake inhibitor. It is concluded that, on striatal neurons, MTX induced Na+ influx only in the presence of external Ca2+. The increase in cytoplasmic Na+ ions then triggers the release of GABA. 相似文献
2.
Jean-Philippe Pin Samuel Weiss Michele Sebben Dorothy E. Kemp Jöel Bockaert 《Journal of neurochemistry》1986,47(2):594-603
Following partial purification, the characteristics of a cytosol protein kinase were investigated. The protein kinase was purified by ammonium sulfate precipitation and diethylaminoethyl-cellulose, ATP-agarose, and hydroxyapatite chromatography. Analysis of the purified protein kinase preparation by polyacrylamide gel electrophoresis revealed three major protein bands. The cytosol protein kinase was purified approximately 442-fold, as calculated from the cyclic nucleotide independent protein kinase activity in the 40,000 g supernatant. The activity of the kinase was found to be independent of either cyclic AMP or cyclic GMP. Moreover, the kinase activity was unaffected by the addition of the endogenous protein kinase inhibitor, or the regulatory subunit from the type II cyclic AMP-dependent protein kinase from bovine heart. The molecular weight of the enzyme was determined to be 95,000 by Sephadex G-200 gel filtration. The activity of the kinase was increased approximately twofold in the presence of 10 microM Ca+2 and calmodulin. This increase was reversed by the addition of EGTA. The subcellular distribution of the protein kinase was also examined. The soluble fraction from nerve terminal was found to have the highest concentration of the kinase activity. 相似文献
3.
P Reisinger K Hochstrasser G J Albrecht K Lempart J P Salier 《Biological chemistry Hoppe-Seyler》1985,366(5):479-483
The N-terminal amino-acid sequence of human ITI has been found to be identical with that of the acid-stable human 30-kDa inhibitors (HI-30) from urine, serum, and those released from inter-alpha-trypsin inhibitor by trypsin or chymotrypsin. Serum HI-30 and HI-30 released by trypsin differ from the urinary inhibitor by an additional C-terminal arginine residue. Compared to these two inhibitors the inhibitor released by chymotryptic proteolysis is elongated C-terminally by an additional phenylalanine residue. These results strongly favour HI-30 as the N-terminus of the inter-alpha-trypsin inhibitor and its release from this inhibitor in vivo by cleavage of the Arg123-Phe124 peptide bond by trypsin-like proteinases. 相似文献
4.
Isolation and characterization of an inter-alpha-trypsin inhibitor-IgG complex from human serum 总被引:1,自引:0,他引:1
J P Salier R Sesboüé K Hochstrasser O Sch?nberger J P Martin 《Biochimica et biophysica acta》1983,742(1):206-214
Inter-alpha-trypsin inhibitor is a human serum protease inhibitor of Mr 180 000 which may release physiological derivatives. A complex between IgG and an inter-alpha-trypsin inhibitor derivative of Mr 30 000 has been recently detected in human serum and was found to be inactive against trypsin, in contrast with the known inhibitory activity of the free 30-kDa derivative. The present study deals with detailed characterization of an inter-alpha-trypsin inhibitor-IgG complex following its purification by affinity chromatography techniques (anti-inter-alpha-trypsin inhibitor immunoadsorbent and Protein A-Sepharose) in mild conditions. The resulting product reacted simultaneously with anti-IgG and anti-inter-alpha-trypsin inhibitor antibodies. This complex contained Mr 180 000 inhibitor at least to some extent. It migrated in the beta-gamma zone in agarose; its molecular weight was estimated to be 1 500 000 or more; part of it displayed covalent bonding between inter-alpha-trypsin inhibitor and IgG; it had a trypsin inhibitor activity. Immunoelectrophoresis allowed one to demonstrate the native complex in serum owing to the use of anti-inter-alpha-trypsin inhibitor and anti-gamma radioactively labelled antibodies. The double immunoreactivity thus evidenced proved to be heterogeneous with respect to its level and location in the native as well as in the purified complex. 相似文献
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7.
Ivo Grabchev Jean-Philippe Soumillion Benoit Muls Galya Ivanova 《Photochemical & photobiological sciences》2004,3(11-12):1032-1037
A new poly(amidoamine) dendrimer from second generation whose periphery comprises sixteen fluorescent 4-N,N-dimethylaminoethylamino-1,8-naphthalimide units has been synthesized and characterized. In DMF, the dendrimer shows sensitivity to the presence of Cu(2+), Fe(3+) and protons. The changes in the fluorescence intensity of the material are in opposite directions if acids or metals are present. Fluorescence enhancements (FE from 5 to 9 depending on solvent) are recorded when the photoinduced electron transfer (PET) originating from the donating amine to the electron accepting naphthalimide is inhibited by the protonation of the N,N-dimethylamino groups. In the case of Cu(2+) cations, a fluorescence quenching (FQ of 6) is first observed, followed by fluorescence partial restoration. In the Fe(3+) case, the same behaviour is observed with a final FE of 2. The successive complexations of these cations by the dendrimer core and by the external rim of the dendrimer may explain the results. 相似文献
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9.
Jean Armengaud Agnès Delaunay-Moisan Jean-Yves Thuret Eelco van Anken Diego Acosta-Alvear Tomás Aragón Carolina Arias Marc Blondel Ineke Braakman Jean-François Collet René Courcol Antoine Danchin Jean-François Deleuze Jean-Philippe Lavigne Sophie Lucas Thomas Michiels Edward R. B. Moore Jonathon Nixon-Abell Ramon Rossello-Mora Zheng-Li Shi Antonio G. Siccardi Roberto Sitia Daniel Tillett Kenneth N. Timmis Michel B. Toledano Peter van der Sluijs Elisa Vicenzi 《Environmental microbiology》2020,22(6):1997-2000
The current SARS-CoV-2 pandemic is wreaking havoc throughout the world and has rapidly become a global health emergency. A central question concerning COVID-19 is why some individuals become sick and others not. Many have pointed already at variation in risk factors between individuals. However, the variable outcome of SARS-CoV-2 infections may, at least in part, be due also to differences between the viral subspecies with which individuals are infected. A more pertinent question is how we are to overcome the current pandemic. A vaccine against SARS-CoV-2 would offer significant relief, although vaccine developers have warned that design, testing and production of vaccines may take a year if not longer. Vaccines are based on a handful of different designs (i), but the earliest vaccines were based on the live, attenuated virus. As has been the case for other viruses during earlier pandemics, SARS-CoV-2 will mutate and may naturally attenuate over time (ii). What makes the current pandemic unique is that, thanks to state-of-the-art nucleic acid sequencing technologies, we can follow in detail how SARS-CoV-2 evolves while it spreads. We argue that knowledge of naturally emerging attenuated SARS-CoV-2 variants across the globe should be of key interest in our fight against the pandemic. 相似文献
10.
Magali Meyer Jérémie Sellam Soraya Fellahi Salma Kotti Jean-Philippe Bastard Olivier Meyer Frédéric Lioté Tabassome Simon Jacqueline Capeau Francis Berenbaum 《Arthritis research & therapy》2013,15(6):R210