Further Evidence for Multiple Forms of an N-Methyl-d-Aspartate Recognition Domain in Rat Brain Using Membrane Binding Techniques

Abstract— Pretreatment with sulfhydryl-reactive agents, such as N-ethylmaleimide and p-chloromercuriphenylsul-fonic acid, invariably resulted in marked inhibition of the binding of dl -(E)-2-amino-4-[³H]propyl-5-phosphono-3-pentenoic acid ([³H]CGP 39653), a competitive antagonist at an N-methyl-d -aspartate (NMDA)-sensitive subclass of central excitatory amino acid receptors, in brain synaptic membranes extensively washed and treated with Triton X-100, but did not significantly affect the binding of L-[³H]-glutamic acid ([³H]Glu), an endogenous agonist. The pre-treatment was effective in reducing the binding of [³H]-CGP 39653 at equilibrium, without altering the initial association rate, and decreased the affinity for the ligand. Pretreatment with sulfhydryl-reactive agents also enhanced the potencies of NMDA agonists to displace [³H]-CGP 39653 binding and attenuated those of NMDA antagonists, but had little effect on the potencies of the agonists and antagonists to displace [³H]Glu binding. The binding of both [³H]CGP 39653 and [³H]Glu was similarly sensitive to pretreatment with four different proteases in Tritontreated membranes, whereas pretreatment with phospho-lipase A₂ or C markedly inhibited [³H]CGP 39653 binding without altering [³H]Glu binding. Moreover, both phospho-lipases not only induced enhancement of the abilities of NMDA agonists to displace the binding of [³H]CGP 39653 and [³H]Glu, but also caused diminution of those of NMDA antagonists. These results suggest that both sulfhydryl-reactive agents and phospholipases may predominantly interfere with radiolabeling of the NMDA recognition domain in a state favorable to an antagonist by [³H]CGP 39653, with concomitant facilitation of that in an agonist-preferring form by [³H]Glu. The possible presence of multiple forms of the NMDA recognition domain is further supported by these data.     

Support for Radiolabeling of a Glycine Recognition Domain on the N-Methyl-d-Aspartate Receptor Ionophore Complex by 5,7-[3H]Dichlorokynurenate in Rat Brain

Abstract: Pretreatment with Triton X-100 more than doubled the binding of radiolabeled 5,7-dichlorokynurenic acid (DCKA), a proposed antagonist at a glycine (Gly) recognition domain on the N-methyl-d -aspartate (NMDA) receptor ionophore complex, in rat brain synaptic membranes. The binding exhibited an inverse temperature dependency, reversibility, and saturability, the binding sites consisting of a single component with a high affinity (27.5 nM) and a relatively low density (2.87 pmol/mg of protein). The binding of both [³H]DCKA and [³H]Gly was similarly displaced by numerous putative agonists and antagonists at the Gly domain in a concentration-dependent manner at a concentration range of 100 nM to 0.1 mM. Among the 24 putative ligands tested, DCKA was the second most potent displacer of the binding of both radioligands with no intrinsic affinity for the binding of [³H]kainic acid and α-amino-3-hydroxy-5-[³H]methylisoxazole-4-propionic acid (AMPA) to the non-NMDA receptors. In contrast, the other proposed potent Gly antagonist, 5,7-dinitroquinoxaline-2,3-dione, was active in displacing the binding of [³H]glutamic ([³H]Glu) and D,L-(E)-2-amino-4-[³H]propyl-5-phosphono-3-pentenoic acids to the NMDA recognition domain with a relatively high affinity for the non-NMDA receptors. In addition, the proposed antagonist at the AMPA-sensitive receptor, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline, not only displaced weakly the binding of both [³H]- Gly and [³H]DCKA, but also inhibited the binding of (+)-5-[³H]methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ([³H]MK-801) to an ion channel associated with the NMDA-sensitive receptor in the presence of added Glu alone in a manner sensitive to antagonism by further added Gly. Clear correlations were seen between potencies of the displacers to displace [³H]DCKA binding and [³H]Gly binding, in addition to between the potencies to displace [³H]-DCKA or [³H]Gly binding and to potentiate or inhibit [³H]MK-801 binding. All quinoxalines tested were invariably more potent displacers of [³H]DCKA binding than [³H]Gly binding, whereas kynurenines were similarly effective in displacing the binding of both [³H]Gly and [³H]-DCKA. These results undoubtedly give support to the proposal that [³H]DCKA is one useful radioligand available in terms of its high selectivity and affinity for the Gly domain in the brain. Possible multiplicity of the Gly domain is suggested by the differential pharmacological profiles between the binding of [³H]Gly and [³H]DCKA.     

Calymenesun granulosa Lu的背壳及接合构造*

描述了Ｃａｌｙｍｅｎｅｓｕｎ ｇｒａｎｕｌｏｓａ Ｌｕ的腹边缘及结合构造,并讨论了此种三叶虫的卷曲机制。认为当其卷曲完善时,尾“边缘“及部分胸肋纳入头颊下,以往描述了尾边缘的部分实际上是尾背结合沟所在位置。卷曲形式为半螺旋卷曲。     

Polymorphic microsatellites and Wilson disease (WD)

Wilson disease (WD), an autosomal recessive disorder of copper metabolism, has been previously mapped to chromosome 13q. Highly informative PCR-based polymorphic microsatellites closely linked to the WD locus (WND) at 13q14.3, as well as sequence-tagged sites for closely linked loci, are described. Two polymorphic microsatellite markers at D13S118 and D13S119 lie within 3 cM of WND. Two others (D13S227 and D13S228) were derived from a yeast artificial chromosome containing D13S31. These were placed on a genetic linkage map of chromosome 13 and were typed in 74 multiplex WD families from a variety of geographic origins (166 affected members). Multipoint analysis provides very high odds that the location of WND is between D13S31/D13S227/D13S228 and D13S59. Previous odds with RFLP-based markers were only 7:1 more likely than any other location. Current odds are 5,000:1. Preclinical testing of three cases of WD by using the highly informative polymorphic microsatellite markers is described. The markers described here ensure that 95% of predictive tests using DNA from both parents and from at least one affected sib will have an accuracy >99%.     

Complementation of bacteriophage lambda integrase mutants: evidence for an intersubunit active site.

Site-specific recombination of bacteriophage lambda starts with the formation of higher-order protein--DNA complexes, called 'intasomes', and is followed by a series of steps, including the initial DNA cleavage, top-strand exchange, branch migration and bottom-strand exchange, to produce recombinant products. One of the intasomes formed during excisive recombination (the attL complex) is composed of the phage-encoded integrase (Int), integration host factor (IHF) and one of the recombination substrates, attL DNA. Int is the catalytic recombinase and has two different DNA binding domains. When IHF is present, Int binds to two types of sites in attL DNA, the three arm-type sites (P'123) and the core-type sites (B and C') where the reciprocal strand exchange takes place. The Tyr342 residue of Int serves as a nucleophile during strand cleavage and covalently attaches to the DNA through a phosphotyrosyl bond. In vitro complementation assays have been performed for strand cleavage using attL suicide substrates and mutant proteins containing amino acid substitutions at residues conserved in the integrase family of recombinases. We demonstrate that at least two Int monomers are required to form the catalytically-competent species that performs cleavage at the B site. It is likely that the active site is formed by two Int monomers.     

崖椒茎的化学成分

从崖椒（Zanthoxglum schinifolutm Sieb.et Zucc.)茎的石油醚、二氯甲烷提取物中分离得到8个化合物。经物理常数测定及光谱（UV,IR,MS,NMR)分析鉴定其为（1）白鲜碱（dictamning),（2）茵芋碱（skimmianine),(3)滨蒿内酯（scoparone),(4)崖椒内酯（schinifolin),(5)莨菪亭（scopoletin),（6）7-羟基-8-甲氧基香豆素（7-hydroxy-8-methoxycoumarin),（7）N-甲基弗林辛（N-methylflindersine),（8）β-谷甾醇（β-sitosterol),其中化合物（5）、（6）和（7）为首次从该植物中分离。     

药用寄生植物菟丝子属,列当属和无根藤属氨基酸的分析

本文测定了菟丝子属、列当属和无根藤属某些种的种子和植株氨基酸的种类组成和含量。结果表明,3个属种子和植株氨基酸均在15种以上,且含量丰富,特别是必需氨基酸的含量较高。文中讨论了氨基酸的药用和在种子鉴定与化学分类上的作用,探讨了开发应用的前景。     

不同放牧强度下高寒灌丛植物的生长特点

 不同放牧强度下高寒灌丛植物在生长发育、生理生态,物质生产和群落结构等方面主要有以下变化：1．在高寒灌丛草场,禾草类、莎草类和灌丛类植物的叶面积指数和平均生长速率随着放牧强度的减轻而增大;随着放牧强度的增加而减小。植株平均高度,植被盖度水平也与放牧强度呈负相关(p<0.01)。2．各项生长分析参数中：叶面积比率(LAR)、叶面积干重比(SLA)和叶干重比(LWR)与放牧强度之间存在负相关。叶面积指数(LAI)与地上生物量呈正相关(p<0.5),地上部现存在量与放牧强度呈负相关(p<0.01)。3．不同放牧强度条件下,高寒灌丛中的禾草类、莎草类、灌丛类和杂类草植物的种类组成和数量变化明显。其中禾草类和莎草类、灌丛类植物的生物量和种类组成比例在重度放牧下减少,在轻度放牧下增大。反之,重度放牧下杂类草的组成和数量明显增加,而轻度放牧下其比例降低。     

枯草杆菌BS224菌在防治Ⅲ°烧伤创面感染中痂下组织细菌数量的动态观察

对48例Ⅲ°烧伤病人的创面,定量植入枯草杆菌BS224菌后,分别在24h、48h、72h及96h做痂下组织细菌定量检测。结果显示:枯草杆菌对痂下组织的致病菌有明显的拮抗作用。感染创面的BS224菌体数量24—48小时显著增加,72—96小时而下降。与清洁创面的BS224菌动态变化上相同,呈常态曲线的规律变化。