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71.
O. Durieu-Trautmann N. Foignant-Chaverot J. Perdomo P. Gounon A. D. Strosberg P. O. Couraud 《In vitro cellular & developmental biology. Animal》1991,27(10):771-778
Summary Early passage bovine brain capillary endothelial cells were immortalized by transfection with the plasmid pSV3 neo. Cells
from one clone, SV-BEC, expressed nuclear SV 40 large T antigen, displayed a contact-inhibited and anchorage-dependent proliferation,
and a high sensitivity to the addition of exogenous basic fibroblast growth factor. SV-BEC cells are morphologically unaltered
and express typical markers of endothelial cells: Factor VIII-related antigen, angiotensin-converting enzyme andGriffonia simplicifolia agglutinin binding site. Endothelium like immunoreactivity was detected in the conditioned medium from these cells. Moreover,
SV-BECs present numerous intercellular tight junctions characteristic of the blood-brain barrier and possess functionalβ1- andβ2-adrenergic receptors, as observed on isolated bovine brain capillaries. 相似文献
72.
The binding of the radioiodinated insect selective neurotoxin from the venom of the scorpion Androctonus australis (AaIT), to synaptic plasma membrane vesicles derived from osmotically shocked insect synaptosomes was studied under kinetic and equilibrium conditions. The integrity of these vesicles and the existence of membrane potential and its modifiability were demonstrated by assays of the uptake of the lipophilic cation tetraphenylphosphonium. It has been shown that 125I-labeled AaIT binds specifically and reversibly to a single class of noninteracting binding sites of high affinity () and low capacity (1.2–2.0 pmol/mg protein). The values of the rate association and dissociation constants k1 and k?1 are, respectively, 1.36 · 106 M?1 · s?1 and 1.9 · 10?3 s?1, and are in a good accordance with the equilibrium constant. The use of various ionophores and changes in external potassium concentration shown to modify the membrane potential of the present neuronal preparation, did not affect the binding of 125I-AaIT, thus indicating its voltage-independence. Veratridine, tetrodotoxin, sea anemone toxin and the α and β scorpion toxins specific for vertebrates did not affect the binding of 125I-AaIT. Furthermore, the above scorpion toxins were devoid of specific binding to the present insect neuronal preparation. Two additional insect toxins derived from the venom of the scorpion Buthotus judaicus, BjIT1 (spastic-excitatory toxin, homologus to the AaIT) and BjIT2 (flaccidity inducing-depressory toxin), were both shown to displace the 125I-AaIT with a high affinity (Kd = 2.2 and 1.3 nM, respectively). These data are compared and discussed in light of the information concerning the interaction of scorpion venom toxins affecting vertebrates with mammalian neuronal tissues. 相似文献
73.
P. Jourdon Y. Berwald-Netter E. Houzet F. Couraud J. M. Dubois 《European biophysics journal : EBJ》1989,16(6):351-356
The effects of toxin II (AaH II) isolated from the scorpion Androtonus australis Hector on sodium current in neuroblastoma X glioma NG 108-15 hybrid cells were analysed under patch clamp conditions in the whole cell configuration. AaH II (70 nM)_induced a maintained sodium current, as well as increasing both fast and slow inactivation time constants and the amplitude of the peak current. This latter effect occurred via a shift of the activation-voltage curve towards negative voltage values by about 9 mV. Oleic acid (5 M), which had no effect on INa under control conditions, decreased the AaH II-induced maintained current. It also reversed, or prevented the increase of the peak current induced by AaH II. However, it neither prevented nor modified the AaH II-induced increase in inactivation time constants. The binding of the toxin to its specific site and the number of binding sites for AaH II were not significantly modified by oleic acid. The oleic acid-induced effects could not be related to the activation of protein kinase C since PMA, a potent activator of this enzyme, did not produce oleic acid-like effects. From these results, it is concluded that AaH II has several independent effects on sodium channels, some of which could be modulated by the lipid environment of sodium channels in the membrane. 相似文献
74.
C. Fédérici L. Camoin C. Créminon N. Chaverot A. D. Strosberg P. O. Couraud 《Journal of neurochemistry》1995,64(3):1008-1015
Abstract: Endothelin-1 (ET-1), originally characterized as a potent vasoconstrictor peptide secreted by vascular endothelial cells, has now been described to possess a wide range of biological activities within the cardiovascular system and in other organs. Brain microvessel endothelial cells, which, together with perivascular astrocytes, constitute the blood-brain barrier, have been shown to secrete ET-1, whereas specific ET-1 receptors are expressed on astrocytes. It is reported here that conditioned medium from primary cultures of mouse embryo astrocytes could significantly, and reversibly, attenuate the accumulation of both ET-1 and its precursor big ET-1 in the supernatant of rat brain microvessel endothelial cells by up to 59 and 76%, respectively, as assessed by immunometric assay. This inhibitor of ET-1 production was purified by gel-exclusion and ion-exchange chromatography as a 280-Da iron-containing molecule, able to release nitrites upon degradation. These results suggest that astrocytes, via release of an iron-nitrogen oxide complex, may be involved in a regulatory loop of ET-1 production at the level of the blood-brain barrier. 相似文献
75.
F. Roux O. Durieu-Trautmann N. Chaverot M. Claire P. Mailly J.-M. Bourre A. D. Strosberg P.-O. Couraud 《Journal of cellular physiology》1994,159(1):101-113
Rat brain microvessel endothelial cells were immortalized by transfection with a plasmid containing the E1A adenovirus gene. One clone, called RBE4, was further characterized. These cells display a nontransformed phenotype and express typical endothelial markers, Factor VIII-related antigen and Bandeiraea simplicifolia binding sites. When RBE4 cells were grown in the presence of bFGF and on collagen-coated dishes, confluent cultures developed sprouts that extend above the monolayer and organized into three-dimensional structures. The activity of the blood-brain barrier-associated enzyme, gamma-glutamyl transpeptidase (γGTP), was expressed in these structures, not in the surrounding monolayer. Similar results were obtained with the microvessel-related enzyme alkaline phosphatase (ALP). Addition of agents that elevate intracellular cAMP reduced the formation of three-dimensional structures, but every cell inside the aggregates still expressed γCTP and ALP activities. Such structures, associated with high levels of γCTP and ALP activities, were also induced by astroglial factors, including (1) plasma membranes from newborn rat primary astrocytes or rat glioma C6 cells, (2) C6 conditioned media, or (3) diffusible factors produced by primary astrocytes grown in the presence of, but not in contact with RBE4 cells. RBE4 cells thus remain sensitive to angiogenic and astroglial factors for the expression of the blood-brain barrier-related γCTP activity, as well as for ALP activity, and could constitute the basis of a valuable in vitro model of the blood-brain barrier. © 1994 wiley-Liss, Inc. 相似文献
76.
Francesca Santostefano Dany Garant Patrick Bergeron Pierre-Olivier Montiglio Denis Réale 《Evolution; international journal of organic evolution》2020,74(1):89-102
Through social interactions, phenotypes of conspecifics can affect an individual's fitness, resulting in social selection. Social selection is assumed to represent a strong and dynamic evolutionary force that can act with or in opposition to natural selection. Few studies, however, have estimated social selection and its contribution to total selection in the wild. We estimated natural and social selection gradients on exploration, docility, and body mass, and their contribution to selection differentials, in a wild eastern chipmunk population (Tamias striatus). We applied trait-based multiple regression models derived from classical phenotypic selection analyses, which allowed us to include several social partners (i.e., neighbors). We detected social selection gradients on female docility and male body mass, indicating that female with docile neighbors and males with large neighbors had lower fitness. In both sexes, social selection gradients varied with the season. However, we found no phenotypic assortment or disassortment for the studied traits. Social selection gradients, therefore, did not contribute to total selection differentials, and natural selection alone could drive phenotypic changes. Evaluating the factors that drive the evolution of the covariance between interacting phenotypes is necessary to understand the role of social selection as an evolutionary force. 相似文献
77.
B Ricard P Fourquet A Massacrier F Couraud 《Biochemical and biophysical research communications》1988,152(3):1031-1037
A monoiodo derivative of rat atrial natriuretic factor (rANF) was shown to specifically bind to rat brain neurones in culture with low binding site capacity (10-20 fmoles per mg of protein) and high affinity (Kd = 50-100 pM). Several analogs of both rat and human ANF competed with 125I-rANF. No change in the number of binding sites was detected upon morphological differentiation of neurones in vitro. Finally a photoreactive derivative of 125I-rANF was prepared and photoaffinity labeling experiments carried out on cultured neurones. After reduction of disulfide bridges, a single band of Mr 60,000 was specifically labeled whereas without reduction, two labeled components of Mr 60,000 and 117,000 were detected. 相似文献
78.
M J Seagar C Labbé-Jullié C Granier J Van Rietschoten F Couraud 《The Journal of biological chemistry》1985,260(7):3895-3898
An azidonitrophenylaminoacetyl mono[125I]iodoapamin derivative was prepared which showed specific binding to rat neuronal membranes. UV photolysis lead to the irreversible occupation of binding sites. Photo-labeling of intact primary cultured rat neurones followed by membrane solubilization, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography revealed the covalent incorporation of radioactivity into 3 main components with Mr = 86,000, 30,000, and 23,000. Labeling was completely prevented by a competing excess of native apamin. Similar studies on purified synaptic membranes from the rat brain showed another labeling pattern with major bands corresponding to Mr = 86,000 and 59,000. Although the reasons for the partial discrepancy between cultured embryonic neurons and an adult brain membrane fraction are not yet clear, we conclude that these proteins are intimately associated with the apamin binding site and are probably components of a type of Ca2+-activated K+ channel. 相似文献
79.
Roy Pierre-Olivier Bulle Cécile Deschênes Louise 《The International Journal of Life Cycle Assessment》2019,24(1):93-103
The International Journal of Life Cycle Assessment - Metals have often been identified as the main contributors to (eco)toxicological impacts in life cycle assessment (LCA) studies. Indeed,... 相似文献