Comparison of simultaneous pH measurements made with 8-hydroxypyrene-1,3,6-trisulphonic acid (HPTS) and pH-sensitive microelectrodes in snail neurones

 We have evaluated the pyrene-based ratiometric fluorescent dye, 8-hydroxypyrene-1,3,6-trisulphonic acid (HPTS), by using it in conjunction with glass pH-sensitive microelectrodes to measure intracellular pH (pH_i) in voltage-clamped snail neurones. Intracellular acidification with propionic acid, and alkalinization following the activation of H⁺ channels allowed the calibration of the dye to be compared with that of the pH microelectrode over the pH range 6.50–7.50. HPTS calibrated in vitro and glass pH-sensitive microelectrodes produced similar absolute resting pH_i values, 7.16±0.05 (n=10) and 7.17±0.06 (n=9) respectively in nominally CO₂/HCO₃ ^–-free saline. At both extremes of the pH range there were small discrepancies. At acidic pH_i, 6.87±0.09 (n=5), the intracellular HPTS measurement differed by –0.08±0.03 pH units from the pH-sensitive microelectrode measurement. At alkaline pH_i,7.32±0.10 (n=5), HPTS measurements produced pH values that differed by +0.07±0.04 pH units from those of the pH-sensitive microelectrode. Some of the discrepancy could be accounted for by the slow response of the recessed-tip pH-sensitive microelectrode (time constant 77±15 s, n=3). Further experiments showed that HPTS, used at an intracellular concentration of 200 μM to 2 mM, did not block activity-dependent pH_i changes. The intracellular HPTS concentration was calculated by measurement of intracellular chloride during a series of HPTS-KCl injections. Comparison of HPTS with 2′,7′-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF), at the same concentration, showed that HPTS produces a larger change in ratio over the pH range 6.00–8.00. Received: 19 February 1998 / Received after revision and accepted: 22 April 1998     

Differential action of TEA+ on two K+-current components of a molluscan neurone

Summary Snail neuronal membranes have two distinct outward current components. Both components are carried by K⁺-ions. They are, however, differentially influenced by Tetraethylammonium. At low concentrations in the external bath (5 mM), TEA⁺ blocks the delayed outward current only. The fast outward current is affected if higher TEA⁺ concentrations are used. Intracellular TEA⁺, applied iontophoretically, blocks both current components in a similar manner.     

Parathyroid hormone enhances calcium current in snail neurones — Simulation of the effect by phorbol esters

Effects of parathyroid hormone substance (PTH) on the voltage-activated calcium current (I _Ca) were studied on intracellularly perfused neurones of the snail, Helix pomatia, under voltage-clamp conditions. Application of 0.1 nM PTH produced a marked potentiation of the current. The effect developed slowly (60–70 min) and remained after removal of PTH. Potentiation could be observed in most neurones, but varied considerably from cell to cell; in some neurones I _Ca was increased 2- to 3-fold. Addition of ethylenebis(oxonitrilo)tetraacetate (EGTA, 10 mM) to, or removal of adenosine 5-triphosphate (ATP, 2 mM) from the intracellular perfusing solution resulted in a suppression or attenuation of the potentiating effect. The effect could be reproduced by the synthetic 1–34 amino acid fragment of PTH. Extracellularly applied protein kinase-C (PK-C) activator phorbol ester phorbol 12-myristate 13-acetate (PMA, 0.1–10 M) produced a similar slow increase in I _Ca (up to 1.5- to 2-fold), while its inactive analogue (4-phorbol ester) had no effect on I_Ca. The effects of PTH and PMA were not additive. PK-C inhibitors [1-(5-isoquinoline-sulphonyl)-2-methylpiperazine hydrochloride] (H-7, 100 M) and staurosporine (100 M) as well as calcium channel antagonists Cd²⁺, verapamil, nifedipine and nimodipine depressed the effect of PTH. The chloride channel blocker 4,4-diisothiocyanato-stilbene-2,2-disulphonic acid (DIDS, 1 mM) did not affect the potentiating action of PTH. Activation of the adelylate cyclase system also potentiated I _Ca in some neurones, but this effect had a different time course and was additive to the effect of PTH. A conclusion is made that activation of PK-C may mediate the slowly developing enhancement of I _Ca by PTH.     

武汉市综合治理垸内钉螺孳生地效果及效益分析

目的对武汉市垸内综合治理控制血吸虫病流行的效果及费用效益进行分析,为决策和评价提供科学依据。方法根据不同地理特点,以环境改造为主,采用沟渠硬化、开新填旧、建鱼池等方法,辅以药物杀灭对垸内钉螺孳生地进行全面综合治理。收集治理前后螺情、人畜病情以及项目费用、疫区经济状况等相关资料,计算螺情、病情指标下降率以及单位效果费用、净效益、费用效益比,进行防治效果评价和费用-效果、费用-效益分析。结果经综合治理,全市有螺处数、有螺面积分别下降了79．93％,85．73％;垸内各流行村人群粪检阳性率下降了58．82％;耕牛粪检阳性率下降了73．14％。项目血防综合效果指数为71．50,费用效益比为1：2．92,净效益费用比为1．92。结论垸内钉螺孳生地综合治理,有效控制了血吸虫病流行,是湖沼型垸内亚型地区控制并消灭血吸虫病的有效对策和措施。     

Snail蛋白在骨肉瘤中的表达及临床意义

目的 观察Snail蛋白在骨肉瘤中的表达,探讨其在骨肉瘤发生、发展中的作用.方法 采用免疫组化SP法检测骨肉瘤组织42例、骨软骨瘤10例中Snail蛋白的表达.结果 ①Snail蛋白在骨肉瘤中表达高于骨软骨瘤组织中的表达,差异有统计学意义(P＜0.01);②Snail蛋白在骨肉瘤组织中的表达与软组织浸润、Ennekin...     

Snail与E-cadherin在食管癌中的表达及临床意义

目的研究食管癌中转录因子Snail及黏附因子E-cadherin的表达,并探讨与食管癌浸润转移的关系。方法采用免疫组化SP法检测68例食管癌组织和40例癌旁组织中Snail,E-cadherin的表达情况,分析两者在不同分化程度的食管癌中的表达,以及与临床病理因素之间的关系。结果食管癌组织Snail阳性率(82.4%)显著高于癌旁组织(42.5%)(p<0.05),Snail的表达与食管癌不同分化程度、浸润深度、淋巴结转移及远处转移有关(p<0.05)。食管癌组织E-cadherin的阳性率(36.7%)显著低于癌旁组织(87.5%)(p<0.05),E-cadherin的表达与食管癌不同分化程度、浸润深度、淋巴结转移、临床分期及远处转移有关(p<0.05)。食管癌组织中Snail与E-cadhrin的表达呈负相关(p<0.05)。结论Snail蛋白高表达与E-cadherin蛋白低表达可能参与食管癌浸润转移的发生,并且联合检测可作为其重要生物学标志,有助于食管癌早期诊断和预后评价。     

血水草杀螺成分-血水草生物碱(ECA)的提取

目的 从血水草中提取杀螺有效成分—血水草生物碱(ECA)。方法 采用70％乙醇渗漉提取，用减压浓缩、酸解、盐析等方法纯化，提取ECA原粉。结果 ECA原粉的提取率为1.009％．结论 本提取方法可靠，设备及工艺流程简单，提取条件易控制，且成本低，便于开发应用。     

Comparative Studies of the Anti-A Agglutinins from Dolichos biflorus and Certain Snails

Abstract. Heterophile anti-A reagents from Dolichos biflorus and several snails were compared with each other by immunodiffusion and immunelectrophoresis. The differences between the lectin and the snail agglutinins were pointed out. Fewer dissimilarities were obtained in hemagglutination inhibition tests using several compounds with α or β-linked N-acetyl-D- galactosamine. In general it was found, that the crude snail anti-A reagents reacted much better with the A determinant, either cellular or soluble, than the purified lectin.