Stretch of mammalian nerve in vitro: effect on compound action potentials

Stretch of nerve has been reported to decrease the amplitude of the compound action potential (CAP) with a complete block appearing in approximately 30 minutes. But for the most part, those experiments were carried out in vivo, and it is generally accepted that the failure of responses was due to a closure of vessels supplying the nerve with a resulting ischemia and anoxia. These studies were undertaken to determine if stretch of nerve has effects that are independent of interference with its vascular supply. In the studies, lengths of rat sciatic and dog peroneal nerves were removed and placed in a chamber supplied with oxygen in which their CAPs were continuously elicited and recorded. This in vitro preparation obviated interference with the nerve's metabolism on stretching. We have previously shown that the form change termed 'beading,' appearing within 10 seconds and reversing as quickly on relaxation, can be elicited with tensions of only several grams. We wished to determine if stretch adequate to produce beading could alter CAPs with the same rapidity. Tensions below 2 g had little effect. On applying tensions of 10-100 g, levels well above those needed to bead the fibers, both increases and decreases of CAP amplitude were seen. The changes occurred within 10 seconds of stretch application, the time at which beading arises with stretch. Although the decreases of CAP amplitudes could be accounted for by beading, the degree of CAP change did not correspond to the amount of tension applied. We hypothesize that the constrictions in the beaded fibers increase axial resistivity and diminish local currents so as to block conduction. The lack of an increasing degree of decreased CAP amplitude with increases in tension is ascribed to the inhibition of elongation offered by the collagen fibrils present in nerve. Collagenase applied to nerves allowed a further increase in length, producing a 'hyperbeading,' showing much longer lengths of beading constrictions on stretch. This would further increase axial resistance and is taken to account for the greater decreases of CAP amplitudes seen following collagenase treatment. To account for those cases where increases of CAP amplitude were seen on stretch, we hypothesize that stretch can also cause an increase in the excitability of the nodes. The outcome of stretch in any given nerve would be the resultant of two opposing actions; beading of the internodes causes a decrease of local currents leading to block of CAPs, while an increased excitability of the nodes acts to augment the responses.     

密封控温技术制备β-环糊精包合物及影响工艺的因素

目的以苯甲酸为模型药物采用新的密封控温技术制备包合物,考察制备工艺中的各种影响因素。方法将主、客分子密封于容器内,通过控制加热温度、时间等因素使主、客分子形成包合物。结果加热温度、时间及载体的晶型等因素对包合过程都会产生影响。结论对苯甲酸-β-环糊精系统采用密封控温技术制备包合物的条件为控温90℃密封加热3 h为最佳;无定形性β-环糊精系统的包合率高于结晶性β-环糊精。     

对贵刊《复方甘草片含服与吞服的镇咳、祛痰疗效比较》一文的验证

读贵刊刊登的《复方甘草片含服与吞服的镇咳、祛痰疗效比较》一文后，笔者采用此法对2003年10月～2004年1月在本门诊部诊治的咳嗽病人218例进行临床验证，现将验证结果报道如下。     

HPLC法测定曲匹布通含量及有关物质

目的:建立RP-HPLC法测定曲匹布通及其有关物质含量。方法:选用Diamond C_(18)柱(250mm×4.6mm,5μm),甲醇-磷酸二氢钾缓冲液(取磷酸二氢钾1.36g加水至1000mL,用磷酸调pH至3.0)(60∶40)为流动相,检测波长271nm,流速:1.0mL·min~(-1),柱温:30℃。结果:曲匹布通在0.08296-0.4148μg·mL~(-1)范围内,线性关系良好,回归方程Y=1869121X-3796,r=0.9999。平均回收率为99.8%(n=6)。结论:本法准确、灵敏、简便。     

中药复方研究中指纹图谱的应用

本文综述了指纹图谱在中药复方研究中的作用以及中药复方研究的新思路，为中药复方的开发研究以及指纹图谱用于质量控制方面的研究提供借鉴。     

2-(E)-(4-甲磺酰基)亚苄基环戊酮Mannich碱类化合物的合成及其抗炎活性

目的设计合成2-(E)-(4-甲磺酰基)亚苄基环戊酮Mannich碱类化合物,并对其抗炎活性进行初步评价.方法以环戊酮、4-甲磺酰基苯甲醛及胺类化合物为原料,经多步反应合成目标化合物,并以二甲苯致小鼠耳肿胀模型测试目标化合物的抗炎活性.结果与结论共合成10个新化合物,经1H-NMR和MS确证其结构.初步药理实验结果显示9个目标化合物均具有一定的抗炎活性.     

穿心莲内酯硝甲基衍生物的合成

目的合成穿心莲内酯硝甲基衍生物.方法利用Michael加成反应机理,将硝甲基基团引入到穿心莲内酯的分子结构中,再对其进行一系列的酯化反应.结果合成了16个新的穿心莲内酯硝甲基衍生物,这些新化合物的分子结构经核磁共振谱、质谱等数据确证.结论化合物Ⅰ1～Ⅰ16显示出不同的抗肿瘤活性.     

复方逍遥合剂中黄芩苷的薄层扫描测定

建立了薄层扫描法测定复方逍遥合剂中黄芩苷含量,并采用TLC法对黄柏、白芍、柴胡、贝母等成分进行鉴别.黄芩苷点样量在0.15～0.75μg范围内线性关系良好(r=0.9987),平均回收率99.2%(RSD 1.5%).     

高效液相色谱法测定复方麻仁丸中大黄素的含量

采用高效液相色谱法测定复方麻仁丸中大黄素的含量.色谱柱:Techsphese ODS C18;流动相:甲醇-水-冰醋酸(80:20:1);流速:1ml·min-1;柱温:25℃;检测波长:254nm.大黄素进样量在0.5～5.0μg内呈现良好的线性关系,r=0.9999,平均回收率为99.73%,RSD为1.57%(n=6).本方法简便,准确,重现性好.     

复方三维亚油酸胶丸Ⅰ中甲基橙皮苷和维生素C的HPLC分析

目的:建立测定复方三维亚油酸胶丸Ⅰ中甲基橙皮苷和维生素 C 的反相高效液相色谱法,并用该方法测定2种不同厂家的药品。方法:采用反相高效液相色谱法,以 Zorbax SB-C_(18)(150 mm×4.6mm,3.5μm)为色谱柱;甲醇-0.03mol·L~(-1)磷酸二氢钠水溶液(pH=2.5)(53:47)为流动相;流速为1.0 mL·min~(-1);检测波长为220 nm 和242 nm;柱温为30℃。结果:甲基橙皮苷在0.64～3.84μg 范围内线性关系良好,其高、中、低3个量的平均加样回收率分别为99.40%,98.18%,97.82%;RSD 分别为0.6%,0.9%,1.0%。维生素 C 在0.50～3.00μg 范围内线性关系良好,其高、中、低3个量的平均加样回收率分别为98.67%,99.22%,96.00%;RSD 分别为0.3%,0.7%,0.4%。结论:该法是一种快速、简便、准确的分析方法,可以为复方三维亚油酸胶丸Ⅰ的质量控制提供科学依据。