Concentration-dependent interactions of the organophosphates chlorpyrifos oxon and methyl paraoxon with human recombinant acetylcholinesterase

For many decades it has been thought that oxygen analogs (oxons) of organophosphorus insecticides phosphorylate the catalytic site of acetylcholinesterase by a mechanism that follows simple Michaelis-Menten kinetics. More recently, the interactions of at least some oxons have been shown to be far more complex and likely involve binding of oxons to a second site on acetylcholinesterase that modulates the inhibitory capacity of other oxon molecules at the catalytic site. The current study has investigated the interactions of chlorpyrifos oxon and methyl paraoxon with human recombinant acetylcholinesterase. Both chlorpyrifos oxon and methyl paraoxon were found to have k(i)'s that change as a function of oxon concentration. Furthermore, 10 nM chlorpyrifos oxon resulted in a transient increase in acetylthiocholine hydrolysis, followed by inhibition. Moreover, in the presence of 100 nM chlorpyrifos oxon, acetylthiocholine was found to influence both the K(d) (binding affinity) and k(2) (phosphorylation constant) of this oxon. Collectively, these results demonstrate that the interactions of chlorpyrifos oxon and methyl paraoxon with acetylcholinesterase cannot be described by simple Michaelis-Menten kinetics but instead support the hypothesis that these oxons bind to a secondary site on acetylcholinesterase, leading to activation/inhibition of the catalytic site, depending on the nature of the substrate and inhibitor. Additionally, these data raise questions regarding the adequacy of estimating risk of low levels of insecticide exposure from direct extrapolation of insecticide dose-response curves since the capacity of individual oxon molecules at low oxon levels could be greater than individual oxon molecules in vivo associated with the dose-response curve.     

Chlamydia pneumoniae DNA in peripheral blood mononuclear cells in dialysis patients,renal transplant recipients and healthy controls

While nitric oxide (NO) is implicated as an important mediator of hypotension in sepsis and endotoxemia, its role as a mediator of tissue injury in shock is controversial. During porcine endotoxemia (lipopolysaccharide (LPS) 1.7 &#119 g·kg -1 ·h -1 i.v. for 6 h), we compared circulatory and morphological changes in the liver induced by two different NO synthase inhibitors (N G -nitro-L-arginine methyl ester, L-NAME, 25 mg·kg- 1 i.v., and aminoethyl-isothiourea, AE-ITU, 10 mg·kg- 1 i.v.), both given after 3 h. LPS induced time-dependent tissue reactions with edema, sinusoidal dilation, packing of red cells and leukocyte infiltration, progressing to endothelial cell and hepatocyte damage, formation of thrombi, and at 6 h widespread necrosis. These changes were similar in all pigs receiving LPS, regardless of treatment with NOS inhibitors. LPS caused significant increases in aspartate aminotransferase (AST), alkaline phosphatase (ALP) and alpha glutathione S-transferase ( &#102 -GST). L-NAME caused further increases in AST, ALP and &#102 -GST, while AE-ITU prevented the late increase in ALP and &#102 -GST observed in the other LPS groups. LPS reduced liver blood flow by ~ 40%. L-NAME further reduced flow by ~ 50%, while AE-ITU restored liver blood flow to baseline values. Conclusion: L-NAME in endotoxemia had detrimental effects on liver circulation, while AE-ITU improved liver blood flow and attenuated the late increase in liver enzymes. Liver morphology was unaffected within the 3-h observation time after NOS inhibition.     

黑龙江省境内松花江沿岸渔（居）民发汞测定结果及分析

对黑龙江省境内松花江沿岸渔（居）民的发样进行总汞和甲基汞分析。通过测定结果可见，发总汞值和甲基汞值均以肇源江段最高。目前发汞值虽比８０年代有所降低，但一部分渔民体内仍有一定量的汞（甲基汞）蓄积，并受到不同程度的汞污染危害。     

EEG evidence that morphine and an enkephalin analog cross the blood-brain barrier

The ability of naltrexone but not methyl naltrexone to cross the blood-brain barrier (BBB) was used to provide a different approach for the demonstration that opiates can enter the brain. Cortical electroencephalographic (EEG) measurements were made in rats receiving peripheral (IP) injections of naltrexone or methyl naltrexone and morphine or an enkephalin analog [Tyr-D-Ala-Gly-MePhe-Met(O)-ol]. Naltrexone significantly blocked the EEG effects of morphine and the enkephalin analog, but methyl naltrexone failed to do so. The results provide biological evidence that an opiate peptide can cross the BBB to affect the activity of the brain.     

miRNA对肿瘤细胞活性影响的探讨

目的试探讨m iRNA对肿瘤细胞活性的影响。方法利用脂质体介导法将5种m iRNA的反义寡核苷酸(AMR)转染至不同的肿瘤细胞,以不相关序列为对照,37℃35%CO2孵箱培养72 h后,用MTT法检测细胞活性。结果不同的m iRNA对肿瘤细胞活性的影响是不同的,既便同一种m iRNA对不同肿瘤细胞活性的影响也有可能是不相同的。结论不同的m icroRNA对肿瘤细胞活性的影响是不同的,同一种m icroRNA对不同肿瘤细胞活性的影响也有可能是不相同的。     

环氧合酶2抑制剂的抗胰腺癌作用及相关机制

目的探讨环氧合酶2(COX-2)抑制剂对胰腺癌细胞增殖、侵袭、迁移能力和对COX-2、基质金属蛋白酶(MMP)-14蛋白表达的影响以及可能的抗胰腺癌机制。方法不同浓度的COX-2抑制剂塞来昔布(20、60、100μmol/L)处理胰腺癌细胞后,用MTT比色法检测细胞的增殖能力;用Transwell侵袭实验和划痕实验检测细胞的侵袭能力和迁移能力;ELISA检测MMP-14和COX-2的蛋白表达情况。结果 MTT增殖实验、Transwell侵袭实验、划痕实验分别提示,COX-2抑制剂作用后胰腺癌细胞的增殖、侵袭、迁移能力均以浓度梯度形式下降(P0.05);ELISA结果显示,胰腺癌细胞中COX-2和MMP-14的蛋白表达水平相应降低(P0.05),两者表达具有显著正相关性(r=0.873,P0.05)。结论 COX-2抑制剂可能通过抑制COX-2表达下调MMP-14表达,进而以浓度梯度形式减弱胰腺癌细胞的增殖、侵袭、迁移能力,起到抗胰腺癌作用。     

3-hydroxy-3-methylglutaryl-coenzyme A reductase in the lobster mandibular organ: regulation by the eyestalk

The mandibular organ (MO) of the lobster, Homarus americanus, produces the isoprenoid methyl farnesoate (MF), a compound related to insect juvenile hormone (JH). To better understand the synthesis and regulation of MF, we studied 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR), the rate-limiting enzyme in isoprenoid biosynthesis. Lobster HMGR had a Km of 11.4 microM for HMG-CoA, a Km of 14.8 microM for NADPH, and was at least 2000-fold more selective for this cofactor than for NADH. Lovastatin and mevalonic acid inhibited HMGR, with KI values of 1.3 nM and 25.3 microM, respectively, whereas MF, farnesoic acid, cholesterol, 20-hydroxyecdysone, and progesterone had no effect. Approximately 75% of the HMGR activity in lobster MO was soluble. Similar levels of HMGR activity were observed in all regions of the MO. Eyestalk removal increased MF synthesis and the activity of farnesoic acid O-methyltransferase (FAOMeT, the final step in MF synthesis) in the MO by 10.7- and 5.7-fold, respectively, and caused a 3.1-fold increase of HMGR activity. Injection of the eyestalk ablated lobsters with an extract of two sinus glands (SG), a neuroendocrine organ in the eyestalk, decreased MF synthesis, FAOMeT activity and HMGR activity to 3, 8, and 20%, respectively, of the levels observed in saline-treated animals. The regulation of crustacean HMGR by the SG suggests that the lobster MO is a useful model system for investigating the cellular regulation of HMGR activity.     

不同吸附剂对血甲基对硫磷灌流清除率的实验研究

目的比较HA230树脂、包膜活性炭、三菱化学SP825树脂和AmberliteXAD16树脂做灌流吸附材料对中毒血样中甲基对硫磷的灌流清除率。方法中毒血样反复流经装有吸附剂的灌流柱,灌流后血样用乙酸乙酯萃取净化,毛细管气相色谱法（火焰光度检测器）测定甲基对硫磷残留量,计算清除率。结果血液中甲基对硫磷浓度较低时,4种吸附剂均有较高的清除率;随着毒物浓度增加,清除率下降,但三菱化学SP825树脂的清除率优于其它3种吸附剂。当每毫升血甲基对硫磷加标量为30μg,吸附剂用量80mg时,三菱化学SP825树脂、HA230树脂和AmberliteXAD16树脂清除率接近,分别为98.6%、97.0%和98.2%,呈现平台趋势;而包膜活性炭120mg用量时,清除率可达96.0%,并可出现近似呈现平台现象,表明对甲基对硫磷的清除已近完全。结论 4种吸附剂中,三菱化学SP825树脂对血中甲基对硫磷清除效果最佳,HA230树脂次之,包膜活性炭和AmberliteXAD16树脂清除效果较前两种吸附剂稍差。     

七氟醚预处理对冠心病人心血管功能的影响及机制作用研究

目的观察七氟醚预处理对于冠心病人心血管功能的影响,探讨其机制作用。方法选择2009年1月至2012年12月期间在本院接受治疗的冠心病患者80例,按随机数字表法分为研究组（4l例）和对照组（39例）,研究组进行七氟醚预处理,对照组给予异丙酚,于麻醉诱导前（T0）、手术进行30min时（T1）、切口缝合后（T2）,以及术后6h（T3）、术后12h（T4）、术后24h（T5）记录患者心率（HR）、中心静脉压（CVP）、平均动脉压（MAP）、每搏输出量（SV）、心排血量（CO）、心脏收缩时间比率（STR）及血清肌钙蛋白T（cTnT）。结果研究组患者的HR、CO、SV、CVP、MAP、STR、cTnT在术前、术中、术后及恢复过程中波动比对照组小,较为平稳。其中,研究组T,时点CO、SV、STR和cTnT分别为（3．48±0．40）L／min、（6．4±1．9）ml／（min·m^2）、（0．36±0．76）、（0．227±0．112）ng／ml,T2时点CO、SV、STR和cTnT分别为（3．58±0．52）L／min、（6．6±2．3）ml／（min·m^2）、（0．36±0．63）、（0．241±0．115）ng／ml,对照组T1时点CO、SV、STR和cTnT分别为（3．11±0．53）L／min、（5．2±2．1）ml／（min·m^2）、（O．46±0．81）、（0．351±0．106）ng／ml,T2时点CO、SV、STR和cTnT分别为（3．15±0．61）L／min、（5．7±1．5）ml／（min·m^2）、（0．44±0．90）、（0．311±0．112）ng／ml,研究组的CO、SV在Tl、T2时点高于对照组,STR在Tl、T2时点低于对照组,cTnT在T1、T2时点低于对照组,且以上组间差异均具有统计学意义（P＜0．05）。结论七氟醚预处理能使患者的血流动力学更加平稳,更适用于临床麻醉,其机制可能与调节肌钙蛋白T的改变有关。     

中西药联合治疗DPN的临床研究

目的：观察中西药联合疗法对糖尿病周围神经病变（DPN）的治疗作用及安全性。方法：选取本院确诊为DPN患者120例,随机分为治疗组与对照组,两组均给予常规降糖治疗,治疗组在常规治疗的基础上加用甲钴胺500μg皮下注射＋糖痹宁口服治疗,对照在常规治疗的基础上仅给予甲钴胺500μg皮下注射治疗,两组均治疗8周,对比治疗前后两组正中神经、腓总神经运动神经传导速度（MNCV）、感觉神经传导速度（SNCV）改善情况,并观察治疗前后两组中医症候评分改善情况及临床疗效。结果：两组治疗后正中神经、腓总神经MNCV、SNCV均较治疗前改善,治疗组改善较对照组更为明显,差异具有统计学意义（P〈0.05）;两组治疗后中医症候评分均较治疗前改善,治疗组治疗后中医症候评分改善程度较对照组更为明显,差异具有统计学意义（P〈0.05）;治疗组治疗后总有效率明显高于对照组,差异有统计学意义（P〈0.05）。结论：甲钴胺联合糖痹宁可有效缓解DPN临床症状,疗效明显,且无明显不良反应,是治疗DPN的有效方案。