Sequences in the proximal 5′ flanking region of the rat neuron-specific enolase (NSE) gene are sufficient for cell type-specific reporter gene expression

We investigated the regulation of the rat neuron-specific enolase gene using a transient transfection approach. Recent transgenic mouse studies have shown that a 1.8-kb segment of the ratNSE gene 5′ flanking region, including the first (noncoding) exon but not the first intron, is able to drive expression of a reporter gene in parallel with endogenousNSE. These data suggest thatcis-acting elements responsible for the spatial and temporal pattern ofNSE gene expression are located within the proximal 1.8 kb of the 5′ flanking sequence. To further investigate this region, we joined the 1.8-kb regulatory cassette to thecat reporter gene and generated a number of constructs in which the flanking sequence was progressively deleted from the 5′ end. These constructs were tested by transient transfection into neuronal and nonneuronal cells, followed by an assay for CAT activity. We found that as little as 255 bp of 5′ flanking sequence was able to confer cell type-specificity on the reporter gene. Further truncation to 120 bp of 5′ sequence resulted in a sharp downregulation of reporter activity in PC12 cells but a significant rise in both Neuro-2A neuroblastoma cells and nonneuronal Ltk- cells, indicating thatcis-acting elements controlling the regulation ofNSE in Ltk-, Neuro-2A, and PC12 cells may lie within the 135 bp region covered by this deletion. This region contains an AP-2 site and an element similar in sequence and position to a motif identified in the proximal promoter region of the neuron-specific peripherin gene. Reduction to 95 bp of 5′ sequence resulted in a slight downregulation of CAT activity in all cell lines tested, and further truncation to 65 bp of 5′ sequence caused a universal reduction to background levels of CAT activity, concomitant with the disruption of the basalNSE promoter. Our results show that the 5′ flanking region of theNSE gene is capable of conferring cell type-specificity on a heterologous gene in transfected cells and that elements responsible for this are located within the proximal 255 bp.     

Stimulation of chloramphenicol acetyltransferase synthesis by cyclic AMP in bacterial cell systems

The effect of cyclic 3,5-adenosine monophosphate (cAMP) on production of the enzyme chloramphenicol acetyltransferase (CAT) by whole bacterial cells was studied in strainsEscherichia coli CSH-2/R222 and WZ-78/R222 (cya₈₅₅). CAT synthesis in strainE. coli WZ-78/R222 was shown to have an intensity only half as great as that of strainE. coli CSH-2/R222. The production of CAT by strainE. coli CSH-2/R222 was increased only very slightly by cAMP, but its effect on the production of this enzyme in strain WZ-78/R222 was appreciable.Research Laboratory of Experimental Immunobiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR, N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 10, pp. 65–66, October, 1975.     

氯霉素乙酰转移酶检测(CAT assay)

本文介绍一种快速方便的外源基因在哺乳动物细胞中瞬间表达检测系统,即氯霉索乙酰转移酶检测系统。该项检测技术不仅对基因的调控顺序(Cis-acting elements)如启动子、增强子等检测提供了有效的工具,而且为真核基因在哺乳动物细胞表达体系中,质粒的构建及筛选提供了行之有效的手段。并介绍了该技术的全过程及其操作要点。     

导数光谱法测定复方氯霉素鱼肝油搽剂中氯霉素的含量

目的：建立复方氯霉素鱼肝油搽剂中氯霉素的含量测定方法。方法：采用一阶导数分光光度法不经分离直接测定氯霉素的含量，检测波长为278nm。结果：氯霉素在浓度为12-28μg／ml内呈线性范围，相关系数r=0．9999。浓度为12、20、28μg／ml的样品液，日内RSD分别为1．00％、1．11％和1．13％，日间RSD分别为1．35％、1．84％和1．67％。浓度为12、16、20、24μg／ml样品液的平均回收率分别为101．58％、99．9％、98．9％、101．13％，RSD值为1．21％。结论：本方法可消除其他组分的干扰，简便易行，适合医院制剂的含量测定。     

高效液相色谱法同时测定氯氟滴眼剂中氯霉素和地塞米松磷酸钠的含量

目的 :建立高效液相色谱法同时测定氯氟滴眼剂中氯霉素和地塞米松磷酸钠的含量。方法 :流动相为甲醇 0 .34%磷酸二氢钾 (5 5∶5 0 ) ,流速 1mL·min-1,SpherisorbC18色谱柱 ,检测波长 2 4 0nm。结果 :氯霉素和地塞米松磷酸钠分别在 12 5～10 0 0mg·L-1(r =0 .9992 )、2 5～ 2 0 0mg·L-1(r =0 .9998)内线性关系良好。加样回收率分别为 (10 1.5± 1.93) %、(10 1.0±1.5 9) % (n =3)。日内RSD分别为 0 .6 3% ,0 .5 8% (n =5 ) ,日间RSD分别为 0 .99% ,0 .86 % (n =3)。结论 :该法简单、迅速 ,结果准确可靠。     

副伤寒甲病例临床分析及药物疗效比较

目的评价3种抗菌药物治疗副伤寒甲沙门菌感染的效果.方法将90例确诊副伤寒甲病例随机分为3组,分别使用洛美沙星、头孢噻肟钠、氯霉素治疗2～3周,观察各项指标,比较疗效.结果洛美沙星退热快,副作用少,疗程短,再燃少;头孢噻肟钠起效也较快,但有再燃的情况;氯霉素价廉,但有再燃及白细胞减少等副作用.结论洛美沙星疗效好,适用于一般药物无效或有严重并发症的患者;头孢噻肟钠、氯霉素可与氨基糖苷类药如西索米星或庆大霉素联用,提高疗效.疗程不足,频频更换抗菌药会增加再燃机会.     

Convenient synthesis of D‐threo‐[dichloroacetyl 1–14C] chloramphenicol

A convenient synthesis of chloramphenicol labelled with carbon‐14 in the dichloroacetyl group at the 1 position is described. It was prepared as part of a 4‐step sequence from [1 ‐ ¹⁴C] glycine and the product was purified by preparative HPLC. A radiochemical yield of 47% was obtained based on [1 ‐ ¹⁴C] glycine and the product had a specific activity of 0.47 mCi/mmol. The procedure can be employed for the synthesis of high specific activity [¹⁴C] chloramphenicol, labelled at 1, 2 or both the positions of dichloroacetyl group. Copyright © 2005 John Wiley & Sons, Ltd.     

复方氯霉素凝胶的研制及质量控制

目的：制备复方氯霉素凝胶剂。方法：以氯霉素、己烯雌酚、硫酸锌为主药，卡泊姆为凝胶基质，制备复方氯霉素凝胶。用导数光谱法控制主药氯霉素的含量。结果：氯霉素的平均回收率为100．74％，RSD为0．29％。结论：该凝胶剂制备工艺简单，凝胶性质稳定，质量可控，可满足临床需求。     

紫外分光光度法测定氯柳酊中氯霉素和水杨酸的含量

目的 :建立氯柳酊中氯霉素和水杨酸含量测定方法。方法 :采用紫外分光光度法 ,利用吸收度的加和性 ,不经分离直接进行含量测定。结果 :氯霉素的测定波长为 2 78nm ,平均回收率为 10 0 .75 % (RSD=0 .70 % ,n =5 ) ;水杨酸的测定波长为 2 30 nm,平均回收率为 99.4 8% (RSD=0 .2 9% ,n =5 )。结论 :本法简便、快速 ,结果准确。     

抗氯霉素单克隆抗体杂交瘤细胞株的制备及筛选

目的获得稳定、高效分泌抗氯霉素单克隆抗体的杂交瘤细胞株。方法以CAP-HS-BSA免疫BALB/c小鼠,用细胞融合技术筛选抗氯霉素单克隆抗体杂交瘤细胞,体内诱生腹水法大量制备单抗。捕获ELISA法测定小鼠免疫球蛋白亚型,间接ELISA法测定腹水效价;用两步硫酸铵法和G蛋白亲和层析法来纯化腹水。结果成功建立了一株分泌抗CAP单克隆抗体（McAb）的杂交瘤细胞4D10。经检测,其分泌的抗体亚类为IgG1,杂交瘤染色体数目90-110条,间接ELISA检测诱生小鼠腹水的抗体效价达1∶2.56×105,纯度达95%,该细胞连续培养生物学性状稳定。结论成功制备的抗氯霉素单克隆抗体4D10效价高、纯度高,为利用该单抗研制检测氯霉素残留试剂盒提供原材料。