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1.
P2X Receptors: An Emerging Channel Family 总被引:16,自引:0,他引:16
Gary Buell Ginetta Collo Francois Rassendren 《The European journal of neuroscience》1996,8(10):2221-2228
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Patrick P. A. Humphrey Gary Buell Ian Kennedy Baljit S. Khakh Anton D. Michel Annmarie Surprenant Derek J. Trezise 《Naunyn-Schmiedeberg's archives of pharmacology》1995,352(6):585-596
Significant advances in understanding of P2X purinoceptor pharmacology have been made in the last few years. The limitations of nucleotide agonists as drug tools have now been amply demonstrated. Fortunately, inhibitors of the degrading ecto-ATPase enzymes are becoming available and it has become apparent that the complete removal of all divalent cations can be used experimentally in some systems to prevent nucleotide breakdown. Despite these issues, convincing evidence for P2X receptor heterogeneity, from data with agonists, has recently been reported.A number of new antagonists at P2X purinoceptors have also recently been described which to some degree appear to be more specific and useful than earlier antagonists like suramin. It is now apparent that suramin is a poor antagonist of ATP in many tissues because it potently inhibits ATPase activity at similar concentrations to those at which it blocks the P2X purinoceptor.Advances in the use of radiolabelled nucleotides as radioligands for binding studies has allowed the demonstration of P2X purinoceptors in a variety of tissues throughout the body including the brain. These studies have also provided evidence for receptor heterogeneity. Excitingly, two P2X purinoceptor genes have been cloned but operational studies suggest that more than two types exist. The cloning studies have also demonstrated a unique structure for the P2X purinoceptor which differentiates it from all other ligand-gated ion channel receptors. Further studies on P2X purinoceptor operation and structure are needed to help resolve controversies alluded to regarding the characterization and classification of nucleotide receptors. Hopefully such studies will also lead to a better understanding of the physiological and pathological importance of ATP and its activation of P2X purinoceptors. This will require the identification of better drug tools, in particular antagonists which may also provide the basis for novel therapeutic agents. 相似文献
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Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
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One of the primary influences on the quality of child care classrooms is teacher behavior, and a critical component of teacher behavior is verbal communication. This study examined the quality of teacher verbalizations with young children in preschool classrooms. Nineteen of the teachers were enrolled in community college courses in early childhood education and child development between pre- and posttesting and fifteen were not. Results indicated that although there was significant improvement on a measure of global classroom quality for those teachers involved in college coursework, teacher verbalizations did not become more appropriate. These findings are discussed in light of current teacher education programs and policy issues. 相似文献
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大狼毒三萜类化学成分的研究 总被引:3,自引:0,他引:3
自大戟科(Euphorbiaceae)植物大狼毒(Euphorbia nematocypha Hand—Mazz)根的乙醇提取物的苯溶解部分,经20%AgNO3硅胶层析,分离得到七个三萜类成分。根据光谱(IR,EIMS,1H—NMR和13C—NMR)和化学方法,确定其中一个化合物为新化合物,命名为大狼毒醇(nematocyphol,Ⅳa),其它化合物为已知物:印度荆芥醇乙酸酯(nepehinol acetate Ⅰ),日尔曼醇乙酸酯(germanicol acetate Ⅱ),大戟醇(euphol,Ⅲ),蒲公英醇(taraxasterol,Ⅴa),24-亚甲基环阿尔廷醇(24-methylenecycloartanol,Ⅴa)和印度荆芥醇(nepehinol,Ⅶa)。这些化合物均为首次从大狼毒中得到。 相似文献
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