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。     

Pharmacokinetics of intravenous chloramphenicol sodium succinate in adult patients with normal renal and hepatic function

The pharmacokinetics of chloramphenicol (CAP) and total chloramphenicol succinate (CAPS) were studied in eight hospitalized adult patients with normal renal and hepatic function receiving intravenous chloramphenicol sodium succinate therapy. The steady-state peak concentrations of CAP (8.4–26.0 g/ml) occurred at an average of 18.0 min (range 5.4–40.2) after cessation of the chloramphenicol sodium succinate infusion. Unhydrolyzed CAPS prodrug, representing 26.0±7.0% of the dose, was recovered unchanged in the urine indicating that the bioavailability of CAP from a dose of intravenous chloramphenicol succinate is not complete. A pharmacokinetic model was developed for simultaneous fitting of CAP and CAPS plasma concentration data. Pharmacokinetic parameters determined by simultaneous fitting were: V, 0.81±0.18 liters/kg; t_1/2, 3.20 ±1.02 hr; CL_B, 3.21±1.27 ml/min/kg for chloramphenicol; and V, 0.38±0.13 liters/kg; t_1/2, 0.57±0.12hr; CL_B, 7.72±1.87 ml/min/kg for total chloramphenicol succinate.Supported in part by Faculty Research Council Grant VF648 from the University of North Carolina.     

紫外分光光度法测定氯霉素滴眼液的含量

目的：测定氯霉素滴眼液的含量。方法：以空白基质溶液为参照液，应用紫外分光光度法，测定波长280nm，消除了处方中羟苯乙酯等成分对测定结果的干扰。结果：平均回收率101.36％，RSD为0.95％。结论：该法简单，快捷，适合医院快速检验。     

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。     

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。     

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。     

高效液相色谱法测定面刺霜中甲硝唑、氯霉素的含量

目的:建立同时测定面刺霜中甲硝唑和氯霉素含量的方法。方法:采用高效液相色谱法,色谱柱为Diamonsil C18(250mm ×4.6mm,5μm),流动相为甲醇(?)水(50:50),检测波长为280nm.结果:甲硝唑、氯霉素在10.0～250.0μg/ml浓度范围内均有良好的线性关系,相关系数均为0.9 998,平均回收率分别为100.54％、100.53％,相对标准差分别为0.79％,0.56％ 结论:本方法分离度好、快速、简便,可用于含甲硝唑、氯霉素霜剂的质量控制。     

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。