Effects of the C-terminal Peptide of the αs subunit of the G protein on the regulation of Adenylyl Cyclase and Protein Kinase A activities by Biogenic Amines and Glucagon in Mollusk and Rat Muscles

The C-terminal parts of the subunits of heteromeric G proteins play an important role in the functional linkage of G proteins with receptors of the serpentine type. The present report describes studies of the effects of the C-terminal octapeptide 387–394 of the _s subunit of the mammalian G protein on the transmission of the hormonal signal via the hormone-sensitive adenylyl cyclase signal system, whose major components are receptors of the serpentine type, G proteins, and the enzymes adenylyl cyclase and protein kinase A. The peptide synthesized here, 387–394 amide (10^–7 - 10^–4 M), dose-dependently decreased adenylyl cyclase and protein kinase A activities stimulated by serotonin and glucagon in smooth muscle from the freshwater bivalve mollusk Anodonta cygnea and by the agonist isoproterenol in rat skeletal muscle. At a concentration as low as 10^–7 M, the peptide released potentiation of the stimulatory effects of hormones on adenylyl cyclase activity due to the non-hydrolyzable guanine nucleotide analog Gpp[NH]p. At the same time, it had almost no effect on the stimulation of adenylyl cyclase activity by non-hormonal agents (NaF, Gpp[NH]p, and forskolin). The inhibitory effects of hormones on adenylyl cyclase and protein kinase A activities persisted in the presence of the peptide. Our data demonstrate the importance of the C-terminal part of the _s subunit of the stimulatory G protein for its functional linkage with receptors of the serpentine type and throw light on the molecular mechanisms of the interactions between G proteins and receptors.Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 89, No. 7, pp. 837–850, July, 2003.     

背角无齿蚌软体组织与养殖场水和沉积物中砷含量测定

目的:测定背角无齿蚌(Anodonta woodiana Lea)软体组织与养殖场中水、沉积物中砷的含量测定。方法:采用原子荧光分光光度法来测定背角无齿蚌养殖场中水、沉积物及体内的重金属元素砷的含量。结果:背角无齿蚌软体组织与养殖场中水、沉积物的砷含量分别为2.08 mg/kg,0.0053 mg/kg,10.04 mg/kg,养殖场沉积物中砷含量远高于背角无齿蚌软体组织的砷含量。结论:背角无齿蚌软体组织对养殖场中砷有很强的颗粒相吸收能力。     

园背角无齿蚌抗肿瘤有效成份的研究——Ⅱ HB-Ⅰ蛋白聚酶的分离、纯化

对园背角无齿蚌抗肿瘤有效组份HB的分离、纯化进行了研究,获得3个纯品,分别定名为HB-Ⅰa、HB-Ⅰb、HB-Ⅰc,分子量分别为6.7万D、6.95万D和6.62万D。     

胡萝卜对叠氮化钠抑制超氧化物岐化酶与胆碱酯酶活性的拮抗作用

近年来，人们在研究某些膳食营养素与肿瘤发生的关系时发现，人类某些恶性肿瘤的发病率与膳食中胡萝卜素水平存在密切关系［１］。类胡萝卜素的抗癌作用已被广泛承认，但对其作用机理尚未完全阐明。目前较一致的看法是类胡萝卜素可增进抗氧化作用，提高机体抗肿瘤免疫功能...     

起搏/除颤螺旋电极植入心肌的急性力学研究

目的对不同构型的螺旋电极旋入及拔出犬心肌的急性力学行为进行测试，为心肌／电极界面的数字建模提供实验依据。方法将实验用犬麻醉后，开胸直视下暴露心腔，将不同头端构型的螺旋电极垂直旋入心肌，通过特殊设计的力学传感器记录电极头端的轴向及扭转受力情况，对比包括心房、心室共11个位点的差异情况；随即将旋入电极以外力强制拔除，记录受力-时间曲线进行分析。结果排除间断施加力量的影响，电极旋入过程的扭矩曲线接近指数曲线，平均扭矩分布范围为0．0003至0．0015，不同构型的电极有明显不同；拔除位点受力以左心室外膜、右心室游离壁、HIS束区域最大，同时可见到明显的不均质性。结论螺旋电极旋入及拔出心肌的受力情况随植入位点、电极头端构型等而不同；心室的受力明显高于心房，其中最牢固位点分别为左心室外膜、右心室游离壁及希氏束。     

圆背角无齿蚌有效组分脂质体抗小鼠肿瘤实验研究

圆背角无齿蚌抗肿瘤有效组分腹腔注射具有抗肿瘤作用,口服无效,对圆背角无齿蚌有效组分脂质体进行口服抗肿瘤实验,采用小鼠移植性肿瘤体内试验。结果表明,剂量为400,200,100mg·kg~(-1)对S_(180)肉瘤,Lewis肺癌,黑色素B16肺转移癌均有显著的抑瘤作用,当剂量为 400mg·kg~(-1)时,对上述 3种瘤株的抑瘤率分别为48.76％,54.38％,52.66％。     

Monitoring the Organotin Contamination in the Taihu Lake of China by Bivalve Mussel Anodonta woodiana

As a part of the pilot study on "Freshwater Mussel Watch", butyltin (monobutyltin, MBT; dibutyltin, DB; tributyltin, TBT), and phenyltins (monophenyltin, MPT; diphenyltin DPT; triphenyltin TPT) were analyzed in soft tissues of 15 bivalve mussels Anodonta woodiana sampled from five separate sites (Huzhou, Xueyan, Dapu, Sansandao, and Wulihu) around the Taihu Lake of China in 2004. The residue of total butyltins and total phenyltins in the all mussels ranged 142-1693 and 3.0-90 ng Sn g(-1) dry weight, respectively. Except for the mussels from Xueyan, DBT and MBT accounted more than 60% of total butyltins in those from other four sites. In contrast, TPT were usually almost 100% of the mussels studied. The present study provides most recent information about the organotin contamination in the Taihu Lake, and suggests Anodonta woodiana can be used as a suitable bioindicator.     

园背角无齿蚌抗肿瘤有效成份的研究：ⅠHB—Ⅱ糖蛋白的分析鉴定

对ＨＢ有效组份分离，纯化得到ＨＢ－Ⅱ，经不连续聚丙烯胺园盘电泳检查，显示一条色带，用凝胶柱层法测定共ＭＷ为１７９００Ｄ，用园盘等电聚焦法测定其ＰＩ值为４．７６，该成份含蛋白质４７．２３％，含糖为２１．１７％，含硫酸基０．４４％，推测其为一种糖蛋白，该成份具有抗肿瘤活性。