混合农药对拟菊酯杀虫剂土壤降解的抑制影响

多菌灵、呋喃丹、丁草胺对3种拟菊酯杀虫剂在粘壤土和砂壤土中的厌气降解有显著的抑制作用。氯氰菊酯、溴氰菊酯和氰戊菊酯在土壤厌气条件下的半衰期分别为20.64、20.82和24.82天,加多菌灵培养可使其分别延长2.30、2.34.3.18倍,加呋喃丹分别延长2.12、2.37、2.37倍;加丁草胺分别延长1.87、1.75、2.58倍。好气条件下,3种拟菊酯杀虫剂降解加快,半衰期分别为11.98、17.64、和21.78天,混合农药对其降解的抑制作用大为降低,仅呋喃丹仍对3种拟菊酯杀虫剂的降解有明显抑制,表明多菌灵、呋喃丹和丁草胺对3种拟菊酯杀虫剂的降解抑制主要是抑制厌氧微生物的结果。     

Beta-adrenergic receptor: stereospecific interaction of iodinated beta-blocking agent with high affinity site

An iodine-labeled beta-adrenergic inhibitor ((125)l-hydroxybenzylpindolol) binds specifically to a site on turkey erythrocyte membranes. A series of beta-adrenergic agonists and inhibitors compete for this binding site, with apparent affinities paralleling biological effectiveness as activators or inhibitors of catecholaminestimulated adenylate cyclase. The activity of d-(+) agonists or inhibitors was 1 percent (or less) than that of the corresponding l-(-) isomers in competing for binding of the iodinated blocker as well as in affecting catecholamine-stimulated adenylate cyclase. 1-(-)-Norepinephrine was about one-tenth as active as l-(-)-isoproterenol in competing for the beta-blocking agent site. The stereospecificity of the interaction with the iodinated beta-blocking agent and the correspondence between affinity for site and biological potency of analogs suggested that this interaction is involved in function of the beta-adrenergic receptor.     

Steroid hormone metabolites are barbiturate-like modulators of the GABA receptor

Two metabolites of the steroid hormones progesterone and deoxycorticosterone, 3 alpha-hydroxy-5 alpha-dihydroprogesterone and 3 alpha, 5 alpha-tetrahydrodeoxycorticosterone, are potent barbiturate-like ligands of the gamma-aminobutyric acid (GABA) receptor-chloride ion channel complex. At concentrations between 10(-7) and 10(-5)M both steroids inhibited binding of the convulsant t-butylbicyclophosphorothionate to the GABA-receptor complex and increased the binding of the benzodiazepine flunitrazepam; they also stimulated chloride uptake (as measured by uptake of 36Cl-) into isolated brain vesicles, and potentiated the inhibitory actions of GABA in cultured rat hippocampal and spinal cord neurons. These data may explain the ability of certain steroid hormones to rapidly alter neuronal excitability and may provide a mechanism for the anesthetic and hypnotic actions of naturally occurring and synthetic anesthetic steroids.     

江西省马尾松毛虫抗药性的研究

江西省各地马尾毛虫抗药性监测结果表明，马尾松毛虫对氰戊菊和氯氰菊的耐药力均有不同程度的提高，尚属耐药力的差异。贵溪、高安林区马公毛虫对溴氰菊酯由已发展到低抗水平，抗性指数分别为５．７和５．９。５种增效剂进行增效作用研究，ＰｂＴ ＳＶ１的增效作用较强，显降低拟除虫菊酯的用量，可延缓抗性的发展。     

正相高效液相色谱法测定梨中5种菊酯类农药多残留

建立正相高效液相色谱方法同时测定梨样品中氯菊酯、甲氰菊酯、氯氰菊酯、溴氰菊酯和高效氯氟氰菊酯5种菊酯类农药残留。采用混合溶剂正己烷-乙酸乙酯(80/20,V/V)提取,在优化的流动相溶剂正己烷-乙酸乙酯(95/5,V/V)及流速1 mL/min,检测波长242 nm条件下,用配备Zorbax Rx-Sil柱、紫外检测器的高效液相色谱仪进行待测组分的分离和测定,检出限范围在0.108~0.193 ng/μL。添加回收率试验结果表明,梨样品中上述5种菊酯类农药加标回收率为74.0%~108.0%,相对标准偏差(RSD%,n=5)为2.4~7.4,其准确度和精密度均达到了农药残留分析的要求。     

Oxidative bioactivation of S-alkyl phosphorothiolate pesticides: stereospecificity of profenofos insecticide activation

The mouse liver microsomal mixed-function oxidase system converts several phosphorothiolate pesticides with S-ethyl, S-propyl, or S-butyl groups to more potent inhibitors of acetylcholinesterase. This activation is stereospecific for the chiral isomers of O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothiolate (profenofos insecticide); the more toxic (-) isomer becomes a 34-fold better inhibitor of acetylcholinesterase in vitro, whereas the less toxic (+) isomer is deactivated by a factor of 2. Prior treatment of the microsomes with piperonyl butoxide or another mixed-function oxidase inhibitor markedly decreases the activation. Piperonyl butoxide also protects against brain acetylcholinesterase inhibition and cholinergic symptoms in chicks resulting from (-)-profenofos administration, thus establishing the importance of the oxidative bioactivation of S-alkyl phosphorothiolate pesticides in vivo.     

溴氰菊酯等杀虫剂防蚜保瓢的初步研究

1984年研究了溴氰菊酯、氰戊菊酯和氯氰菊酯对棉蚜及其天敌异色瓢虫的影响,结果表明,氰戊菊酯对异色瓢虫的毒力较溴氰菊酯、氯氰菊酯及乐果为低。在瓢虫发生盛期,防治棉蚜宜使用氰戊菊酯。     

Does the binding of cyclosporine to calmodulin result in immunosuppression?

The cyclosporines are a family of cyclic endecapeptides that cause a profound suppression of primary immune stimulation both in vitro and in vivo. Recently, the regulatory protein calmodulin (CaM) has been implicated as a target for cyclosporin A (CsA) binding. This study utilized two less-active isomers of CsA to evaluate the specificity and biological significance of CaM binding. The three cyclosporines exhibited equivalent in vitro binding to CaM, regardless of immunosuppressive activity. Furthermore, CaM-dependent enzyme systems were inhibited equally by active and inactive cyclosporines, but only at concentrations 100 times those necessary to block lymphocyte activation. Thus the exquisite immunosuppressive stereospecificity displayed by cyclosporine isomers is not reflected in the binding to and inhibition of CaM, suggesting that inhibition of CaM-dependent processes is not sufficient to explain the immunosuppressive activity of CsA.     

山西苹果黄蚜对菊酯类杀虫剂的抗性监测

采用点滴法测定了山西省三地区苹果黄蚜 (AphispomiDeGeer)对 7种菊酯类杀虫剂的敏感性。结果表明 ,用药水平不同的三个地区苹果黄蚜对菊酯类杀虫剂的敏感性有明显差异。以忻州种群为相对敏感种群 ,晋中苹果黄蚜对高效氯氰菊酯、功夫菊酯、溴氰菊酯、百树菊酯、甲氰菊酯、氯氰菊酯、氰戊菊酯的抗性倍数分别为 :1 10倍、 1 0 2倍、 3 0 6倍、 1 11倍、 0 6 7倍、 0 87倍、 1 35倍 ;运城苹果黄蚜对上述 7种杀虫剂的抗性倍数分别为 :6 76倍、 13 17倍、 13 87倍、 11 32倍、 5 2 5 2倍、 9 76倍、 15 92倍。运城地区苹果黄蚜对菊酯类杀虫剂已产生低到高水平抗性     

酶抑制剂与杀虫剂混配对黄曲条跳甲抗药性的抑制作用

研究了磷酸三苯酯(TPP)、胡椒基丁醚(PB)和顺丁烯二酸二乙酯(DEM)3种酶抑制剂对黄曲条跳甲Phyllotretastriolata的杀虫剂敏感性的影响.结果表明:TPP对甲胺磷、敌敌畏、灭多威、氰戊菊酯、氯氰菊酯、氟虫腈和阿维菌素均有显著增效作用;除对敌敌畏的增效作用低于PB外,TPP对其余6种杀虫剂的增效作用均高于PB和DEM;PB对甲胺磷、敌敌畏、灭多威、氰戊菊酯和氯氰菊酯,DEM对甲胺磷、敌敌畏和氯氰菊酯的增效比均大于2.0,但PB对甲胺磷、灭多威以及DEM对甲胺磷、敌敌畏的增效作用不显著;PB对氟虫腈和阿维菌素以及DEM对灭多威、氰戊菊酯、氟虫腈和阿维菌素的增效作用较低或不明显;辛硫磷、毒死蜱和氟虫腈对黄曲条跳甲的毒力远大于甲胺磷、敌敌畏、灭多威、氰戊菊酯和氯氰菊酯.分别采用辛硫磷、毒死蜱和氟虫腈与氰戊菊酯或氯氰菊酯混配后的增效作用显著.故采用酶抑制剂与杀虫剂混配可有效抑制黄曲条跳甲对一些杀虫剂的抗性.     

Structural mechanism for statin inhibition of HMG-CoA reductase

HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase (HMGR) catalyzes the committed step in cholesterol biosynthesis. Statins are HMGR inhibitors with inhibition constant values in the nanomolar range that effectively lower serum cholesterol levels and are widely prescribed in the treatment of hypercholesterolemia. We have determined structures of the catalytic portion of human HMGR complexed with six different statins. The statins occupy a portion of the binding site of HMG-CoA, thus blocking access of this substrate to the active site. Near the carboxyl terminus of HMGR, several catalytically relevant residues are disordered in the enzyme-statin complexes. If these residues were not flexible, they would sterically hinder statin binding.     

德国小蠊的抗药性及多功能氧化酶在抗性中的作用

通过敏感性测定、增效作用试验和酶活力测定,分析了德国小蠊对拟除虫菊酯类药剂的抗药性 以及多功能氧化酶在抗药性中的作用,结果表明采自杭州的德国小蠊品系对二氯苯醚菊酯、溴氰菊酯和 氯氰菊酯的抗性系数分别是敏感品系的６７．１倍, １８．１倍和１１．８倍,利用多功能氧化酶的抑制剂── 氧化胡椒基丁醚作为增效剂测定抗性品系对二氯苯醚菊酯的增效作用,增效３．６９倍,离体酶活力测定 的结果表明,抗性品系中多功能氧化酶活力明显高于敏感品系,由此认为,德国小蠊的杭州品系已对拟 除虫菊酯药剂产生了抗药性,多功能氧化酶活力增强是导致德国小蠊抗药性产生和发展的重要原因。     

Model structure for the inflammatory protein C5a

The complement cleavage product C5a is a potent stimulant of inflammatory processes; thus, inhibition of C5a activity is of therapeutic interest. The three-dimensional structure of the major portion of C5a was modeled from the homologous C3a crystal structure by comparative modeling techniques. The model shows that core residues of C5a are completely conserved, while external residues differ from C3a. Even though the amino-terminal 12 residues of C3a are disordered in the crystal, this sequence in C5a may form an amphipathic helix. The distribution of species sequence differences in the complete C5a structure suggests a possible receptor binding site.     

陕西棉花苗蚜对几种杀虫剂的抗药性测定

１９９０～１９９５年间在陕西渭南、三原、大荔棉区，采用毛细管点滴法测定了棉花苗蚜对九种常用有机磷及菊酯类杀虫剂的抗药性。结果表明，与敏感种群相比，陕西各棉区苗蚜对有机磷类杀虫剂基本处于敏感水平；对久效磷的抗性相对较高，其ＲＲ值为２．５～４．５．对菊酯类杀虫剂则表现出极高的抗药性，１９９５年测定发现，对溴氰菊酯的ＲＲ值高达１３４５７１；而对氯氰菊酯则相对敏感些，三原苗蚜仅为１４．３６；而渭南苗蚜种群则高达１６４．８６     

Solution structure of kistrin, a potent platelet aggregation inhibitor and GP IIb-IIIa antagonist.

The structure of kistrin, which is a member of a homologous family of glycoprotein IIb-IIIa (GP IIb-IIIa) antagonists and potent protein inhibitors of platelet aggregation, has been determined by two-dimensional nuclear magnetic resonance (NMR) spectroscopy. The 68-residue protein consists of a series of tightly packed loops held together by six disulfide bonds and has almost no regular secondary structure. Kistrin has an Arg-Gly-Asp (RGD) adhesion site recognition sequence important for binding to GP IIb-IIIa that is located at the apex of a long loop across the surface of the protein.     

Harnessing chaperones to generate small-molecule inhibitors of amyloid beta aggregation

Protein aggregation is involved in the pathogenesis of neurodegenerative diseases and hence is considered an attractive target for therapeutic intervention. However, protein-protein interactions are exceedingly difficult to inhibit. Small molecules lack sufficient steric bulk to prevent interactions between large peptide surfaces. To yield potent inhibitors of beta-amyloid (Abeta) aggregation, we synthesized small molecules that increase their steric bulk by binding to chaperones but also have a moiety available for interaction with Abeta. This strategy yields potent inhibitors of Abeta aggregation and could lead to therapeutics for Alzheimer's disease and other forms of neurodegeneration.     

固相萃取与GC-μECD法测定香蕉中有机氯和拟除虫菊酯类农药残留

【目的】利用气相色谱—微电子捕获方法（GC-μECD）建立可同时检测香蕉中有机氯和拟除虫菊酯类农药的方法,为香蕉的食用安全提供保障。【方法】香蕉中有机氯和拟除虫菊酯类农药残留经乙腈溶液萃取分层,乙腈相浓缩后过弗罗里硅土柱净化,采用丙酮—正己烷溶液5 mL淋洗,淋洗液经氮吹仪吹干后,用正己烷定容至5 mL,供GC测定。将13种标液混合稀释成1.000 μg/mL,六六六、滴滴涕、氯氰菊酯、氟氰戊菊酯、氰戊菊酯和溴氰菊酯稀释为0.005、0.010、0.020、0.040、0.080、0.100、0.200 μg/mL,百菌清为0.005、0.010、0.020、0.040、0.080 μg/mL,配制成混合标准溶液,以峰面积为纵坐标、质量浓度为横坐标绘制标准曲线图。香蕉样品中加标浓度分3个水平：六六六、滴滴涕为分别0.005、0.010、0.050 mg/kg,百菌清、氯氰菊酯、氟氰戊菊酯、氰戊菊酯和溴氰菊酯为分别0.010、0.050、0.100 mg/kg进行回收率试验。根据最低加标浓度基线噪声的3倍换算各分析物的最低仪器检出限。【结果】各曲线呈良好线性关系,仪器检出限为0.5~5.0 μg/L,回收率为70.4%~118.7%,相对标准偏差为2.45%~11.50%。【结论】GC-μECD方法可同时检测香蕉中13种有机氯和拟除虫菊酯类农药残留,且具有精密度和准确度高、操作简单方便、分离效果好、回收率高、重现性好等优点,适合香蕉农药残留的检测。     

Stereospecific effects of inhalational general anesthetic optical isomers on nerve ion channels

Although it is generally agreed that general anesthetics ultimately act on neuronal ion channels, there is considerable controversy over whether this occurs by direct binding to protein or secondarily by nonspecific perturbation of lipids. Very pure optical isomers of the inhalational general anesthetic isoflurane exhibited clear stereoselectivity in their effects on particularly sensitive ion channels in identified molluscan central nervous system neurons. At the human median effect dose (ED50) for general anesthesia, the (+)-isomer was about twofold more effective than the (-)-isomer both in eliciting the anesthetic-activated potassium current IK(An) and in inhibiting a current mediated by neuronal nicotinic acetylcholine receptors. For inhibiting the much less sensitive transient potassium current IA, the (-)-isomer was marginally more potent than the (+)-isomer. Both isomers were equally effective at disrupting lipid bilayers.     

氯氰菊酯与DNA相互作用的光谱研究

[目的]对农药氯氰菊酯与DNA的相互作用进行研究,揭示其致畸的作用机制。[方法]在pH值7．4的‘蹦s．HCI缓冲溶液体系中,利用紫外吸收光谱法和荧光探针,对氯氰菊酯与DNA的结合方式和结合常数进行研究。[结果]氯氰菊酯在256nm处的紫外吸收峰随着DNA的加入发生了显著蓝移,同时吸光强度逐渐增大,DNA在203ntn处的紫外吸收峰随着氯氰菊酯的加入发生了显著红移,同时吸光强度逐渐降低,这说明氯氰菊酯与DNA形成了复合物;固定DNA浓度（3．4×10^-4moll／L）,改变氯氰菊酯浓度（1×10^-5 6×10^-5mol／L）,在203nm处测定吸光度,计算得到37℃时结合常数K为7．19×10^3L／mol;结合荧光探针试验证明氯氰菊酯与DNA是以沟槽方式结合。l结论I氯氰菊酯与DNA以沟槽方式结合可能是氯氰菊酯具有致畸作用的原因．