磷,砷,四氯化碳肝损伤线粒体和微粒体乳酸脱氢酶同工酶的改变

本文对P4,NaAsO_2,CCl_4亚慢性肝损伤大鼠肝细胞线粒体,微粒体LDH同工酶进行聚丙烯酰胺凝胶电泳,光密度扫描定量,对其标志酶组化染色,微机图象定量分析,结果表明,三组动物肝小叶线粒体标志酶SDH活性均有下降,其中以CCl_4组SDH下降较迟.NaAsO_2组染毒第8wk可见线粒体LDH_5升高,染毒12wk LDH_(2,3)下降,LDH_5升高与对照组比较无显著性差异,但仍高于P_4组,各组间微粒体LDH同工酶和其标志酶G-6-P酶活性变化存在差异;P_4组微粒体LDH同工酶改变明显且较其他两组早。     

hTERT phosphorylation by PKC is essential for telomerase holoprotein integrity and enzyme activity in head neck cancer cells

Telomerase activity is suppressed in normal somatic tissues but is activated in most cancer cells. We have previously found that all six telomerase subunit proteins, including hTERT and hsp90 are needed for full enzyme activity. Telomerase activity has been reported to be upregulated by protein kinase C (PKC), but the mechanism is not clear. In this study, we examined how PKC regulates telomerase activity in head and neck cancer cells. PKC inhibitor, bisindolylmaleimide I (BIS), inhibited telomerase activity but had no effect on the expressions of telomerase core subunits. RNA interference (RNAi) and in vitro phosphorylation studies revealed that PKC isoforms alpha, beta, delta, epsilon, zeta specifically involved in telomerase regulation, and the phosphorylation target was on hTERT. Treatment with the hsp-90 inhibitor novobiocin dissociated hsp90 and hTERT as revealed by immunoprecipitation and immunoblot analysis and reduced telomerase activity. Treatment with the PKC activator SC-10 restored the association of hsp90 and hTERT and reactivate telomerase, suggesting that hTERT phosphorylation by PKC is essential for telomerase holoenzyme integrity and function. Analysis on clinical normal and tumour tissues reveal that the expressions of PKC alpha, beta, delta, epsilon, zeta were higher in the tumour tissues, correlated with telomerase activity. Disruption of PKC phosphorylation by BIS significantly increased chemosensitivity to cisplatin. In conclusion, PKC isoenzymes alpha, beta, delta, epsilon, zeta regulate telomerase activity in head and neck cancer cells by phosphorylating hTERT. This phosphorylation is essential for telomerase holoenzyme assembly, leading to telomerase activation and oncogenesis. Manipulation of telomerase activity by PKC inhibitors is worth exploring as an adjuvant therapeutic approach.     

前列地尔与川芎嗪、黄芪合用对大鼠心肌缺血再灌注损伤的保护作用

目的 :观察前列地尔与川芎嗪 (LT )、黄芪(AM ) 3药合用对大鼠心肌缺血再灌注损伤的保护作用。方法 :采用在体大鼠开胸结扎冠状动脉左室支 30min后 ,松扎再灌注 60min造成心肌缺血再灌注模型并以 0 .9%氯化钠注射液为模型对照 ,观察 3药 :前列地尔 31.2 5μg·kg- 1,川芎嗪 2 5mg·kg- 1,黄芪 4 15mg·kg- 1合用对再灌注心肌组织中超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶(GSH PX)活力 ,丙二醛 (MAD)、Ca2 +含量及血清肌酸磷酸激酶同功酶 (CK MB)含量的变化 ,并同时心电图监测心律失常情况。结果 :与模型对照组相比3药合用可提高再灌注心肌组织中SOD ,GSH PX活力 ,差异有非常显著意义 (P <0 .0 1) ;并能降低再灌注心肌组织中MDA ,Ca2 +含量及血清CK MB含量 ,差异有非常显著意义 (P <0 .0 1) ;防止再灌注室性心律失常的发生 ,缩短心律失常的维持时间 ,降低ST段抬高的程度 ,差异有非常显著意义 (P <0 .0 1)。结论 :前列地尔与LT ,AM合用在保护心肌缺血再灌注损伤中有显著的作用 ,其保护作用主要与清除自由基有关     

Phosphodiesterase profile of human B lymphocytes from normal and atopic donors and the effects of PDE inhibition on B cell proliferation

1. CD19⁺ B lymphocytes were purified from the peripheral blood of normal and atopic subjects to analyse and compare the phosphodiesterase (PDE) activity profile, PDE mRNA expression and the importance of PDE activity for the regulation of B cell function.
2. The majority of cyclic AMP hydrolyzing activity of human B cells was cytosolic PDE4, followed by cytosolic PDE7-like activity; marginal PDE3 activity was found only in the particulate B cell fraction. PDE1, PDE2 and PDE5 activities were not detected.
3. By cDNA-PCR analysis mRNA of the PDE4 subtypes A, B (splice variant PDE4B2) and D were detected. In addition, a weak signal for PDE3A was found.
4. No differences in PDE activities or mRNA expression of PDE subtypes were found in B cells from either normal or atopic subjects.
5. Stimulation of B lymphocytes with the polyclonal stimulus lipopolysaccharide (LPS) induced a proliferative response in a time- and concentration-dependent manner, which was increased in the presence of interleukin-4 (IL-4). PDE4 inhibitors (rolipram, piclamilast) led to an increase in the cellular cyclic AMP concentration and to an augmentation of proliferation, whereas a PDE3 inhibitor (motapizone) was ineffective, which is in accordance with the PDE profile found. The proliferation enhancing effect of the PDE4 inhibitors was partly mimicked by the cyclic AMP analogues dibutyryl (db) cyclic AMP and 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole-3′,5′-cyclic monophosphorothioate, Sp-isomer (dcl-cBIMPS), respectively. However, at concentrations exceeding 100 μM db-cyclic AMP suppressed B lymphocyte proliferation, probably as a result of cytotoxicity. Prostaglandin E₂ (PGE₂, 1 μM) and forskolin (10 μM) did not affect B cell proliferation, even when given in combination with rolipram.
6. Inhibition of protein kinase A (PKA) by differentially acting selective inhibitors (KT 5720, Rp-8-Br-cyclic AMPS) decreased the proliferative response of control cells and reversed the proliferation enhancing effects of rolipram.
7. Importantly, PDE4 activity in LPS/IL-4-activated B lymphocytes decreased by about 50% compared to unstimulated control values.
8. We conclude that an increase in cyclic AMP, mediated by down-regulation of PDE4 activity, is involved in the stimulation of B cell proliferation in response to LPS/IL-4. B cell proliferation in response to a mitogenic stimulus can be further enhanced by pharmacological elevation of cyclic AMP.

     

Labelling of I2B-imidazoline receptors by [3H]2-(2-benzofuranyl)-2-imidazoline (2-BFI) in rat brain and liver: characterization, regulation and relation to monoamine oxidase enzymes

The novel selective imidazoline radioligand [3H]2-(2-benzofuranyl)-2-imidazoline (2-BFI) was used to characterize and assess further the nature of I₂-imidazoline receptors in rat brain and liver. In the cerebral cortex, 2-BFI displayed high affinity (K _i= 9.8 nM) for a single class of [³H]2-BFI binding sites. Other imidazoline/guanidine compounds (e.g. aganodine, cirazoline and idazoxan) displayed biphasic competition curves, indicating the existence of high (K _iH= 2.9-78 nM; R _H= 61-83%) and low (K _iL= 4.7-158 μM) affinity sites. The pharmacological profile for [³H]2-BFI binding (aganodine > cirazoline > 2-BFI >> clonidine > amiloride >> efaroxan) was typical of that for I₂-sites. This profile was almost identical to that obtained against [³H]idazoxan (correlation between pK _i values, r = 0.97) which indicated that the sites characterized with [³H]2-BFI in brain corresponded to I₂-imidazoline receptors. The low affinity of amiloride against [³H]2-BFI (K _i= 900 nM) further indicated that these brain I₂-sites belong to the I_2B-subtype. [³H]2-BFI binding sites (B _max= 72 fmol/mg protein) in brain were differentially modulated by treatment (7 days) with cirazoline (up-regulation: 25%) and the MAO inhibitor phenelzine (down-regulation: 31%), indicating that these I₂-sites are regulated in vivo, as is the case for those labelled by [³H]idazoxan. Chronic treatment with 2-phenylethylamine, a phenelzine metabolite and endogenous amine, did not alter the density of brain of I₂-imidazoline receptors labelled by [³H]idazoxan. Preincubation of liver membranes with the MAO inhibitor clorgyline (10^-7 M) abolished the binding of [³H]Ro 41-1049 (N-(2-aminoethyl)-5-(m-fluorophenyl)-4-thiazole carboxamide) to MAO-A, but it did not alter the binding of [³H]Ro 19-6327 (N-(2-aminoethyl)-5-chloro-2-pyridine carboxamide) to MAO-B or that of [³H]2-BFI to I₂-sites. At 10^-4 M it also abolished MAO-B sites, but a substantial proportion of I₂-sites (40%) remained intact. Preincubation of liver membranes at 60 °C also abolished MAO-A/B sites, whereas still 22% of I₂-sites remained. The results indicate that [³H]2-BFI is a good tool for the identification of I₂-imidazoline receptors and suggest further that certain I₂-sites and MAO are different proteins. Received: 10 January 1997 / Accepted: 6 March 1997     

血清乳酸脱氢酶及其同工酶测定的临床价值

对171例患者及31例健康人血清LDH及其LDHi进行测定,结果发现:患者LDH总活性都普遍升高,LDHi酶谱的变化以AMI及病毒性心肌炎最为显著,其中LDHi分别为43.27%和34.86%,LDH_1/LDH_2都大于1,分别是1.58和1.30,肝炎患者LDH_5升高明显;原发性肝癌LDH总活性升高的同时LDH_5也升高,有的高达34%。     

槲寄生总碱和多糖对黄曲霉菌毒素诱发大鼠肝癌前病变时血清同工酶含量的影响

目的研究槲寄生提取物对黄曲霉毒素B1(AFB1)诱发大鼠肝癌前病变时同工酶含量的影响。方法60只大鼠被分为正常对照组、单纯肝大部切除组、AFB1模型组、槲寄生总碱组和槲寄生多糖组。后3组大鼠一次性ip给予AFB10.75mg·kg-1,第3周起饲以含0.015%二乙酰氨基芴饲料5周。后4组大鼠于第3周末施行肝大部切除术。槲寄生总碱和槲寄生多糖组于肝大部切除术后1周开始分别ig给予槲寄生总碱8g·kg-1和槲寄生多糖6g·kg-1,每天1次,连续给药4周。第8周末处死大鼠,采用组织化学染色法检测肝组织切片中γ-谷氨酰转肽酶(GGT)阳性染色面积;免疫吸附法测定血清GGT同工酶Ⅱ(GGTⅡ)阳性表达;酶速率法和琼脂糖电泳法测定血清乳酸脱氢酶(LDH)和碱性磷酸酶(ALP)总活性及其同工酶相对含量。结果AFB1引起肝脏组织中GGT表达明显增加;大鼠血清GGTⅡ阳性率明显升高;血清LDH总活性和LDH5含量增高,且LDH5>LDH4;血清ALP1含量明显升高,并出现异常ALP电泳条带。大鼠ig给予槲寄生总碱或槲寄生多糖治疗4周,肝脏组织中GGT表达明显减少,血清GGTⅡ阳性率明显下降,血清LDH总活力、LDH5和ALP1含量均较模型组明显降低。结论AFB1诱发的大鼠肝癌前病变有多种同工酶的表达异常,槲寄生总碱和多糖可能通过调节同工酶的表达干预肝癌前病变的发生和发展。     

The effect of three H2 receptor antagonists on the disposition of cyclosporin a in the in situ perfused rat liver model

The in situ, perfused rat liver model was used to investigate the effect of three H₂ receptor antagonists on the disposition of cyclosporin A (CyA) and the major human metabolite, AM1. Perfusion experiments, using standard techniques, were carried out on four groups (one control and three H₂-receptor antagonist-treated groups) of male Sprague-Dawley rats (300–350 g). All animals received CyA, 2.5 mg; the three treated groups received cimetidine (8 mg), ranitidine (3 mg), or famotidine (0.4 mg). Perfusated and bile samples were collected and assayed for CyA, AM1, and the H₂ receptor antagonists by HPLC. Results indicated that CyA perfusate concentrations in the controls and cimetidine and ranitidine-treated groups were not significantly different, although levels in the famotidine group were significantly higher at all times (p<0.05), except 30 min, compared to the controls. However, examination of the AM1 perfusate and bile data and the apparent metabolic clearance data indicated that CyA metabolism was still occurring, despite the presence of the H₂ receptor antagonist. It is suggested that the absence of a interaction may be attributed to a lack of specificity of the H₂ receptor antagonists for CYP3A, the isoenzyme responsible for CyA metabolism.     

牛皮蝇不同发育阶段五种同工酶的比较分析

本文应用聚丙烯酰胺凝胶电泳技术(PAGE):1,对我国西北地区的牛皮蝇(Hypoderma bovis)的Ⅱ、Ⅲ龄幼虫和蛹期作了酯酶(EST)、乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)、葡萄糖-6-磷酸脱氢酶(G6PD)和异柠檬酸脱氢酶(ICDH)等五种同工酶的比较测定。结果表明在牛皮蝇生活史的不同发育阶段,其中四种同工酶(除ICDH外)的酶带数目和相对迁移率(R_f)均有差异;2,将专性寄生性蝇类——牛皮蝇与营自由生活的蝇类——舍蝇(Musca domestica vicina macquart)进行了相同发育阶段的五种同工酶对比,发现二者在酶带数目和R_f上均有显著差别。本文认为,在牛皮蝇不同发育阶段有着不同的控制基因以适应虫体生长代谢的需要。而寄生性蝇类与非寄生性蝇类也可由于生态环境完全不同而形成不同的代谢途径。     

猴头部冲击性脑损伤的判别

为在航空弹射救生的头部冲击伤的研究中区别脑功能性与器质性损伤的界限，使用高速动态加载机，对２４只猴头进行了不同冲击载荷的撞击实验，依据有关临床诊断标准判别，冲击后８只猴发生了单纯性脑震荡，６只猴发生了脑实质性损伤，而其中的３只猴又伴有脑震荡症状。结果表明，发生了脑震荡的猴都出现了暂短生理反射减弱或消失，呼吸和心率减慢，脑干神经细胞尼氏体有减少现象脑震荡伴有脑损伤的猴脑脊液中还检出ＣＫ－ＢＢ酶和红细