伯氏疟原虫对青蒿素抗药性的研究

仿Peters剂量递增法用伯氏疟原虫ANKA株及N株对QHS进行了抗药性的研究。经14个月的培育至第58代,QHS im注射“4日抑制性实验”的ED_(50)在RQ/ANKA系及RQ/N系分别为其亲代系的53.4及54.6倍,但经蚊传未获成功。在第40代(I_(50)=25)时,其50%的治愈剂量为其亲代系的5.4倍。停药传代其抗性会逐渐消失。该虫系对青蒿酯钠及蒿甲醚有明显的交叉抗性,其ED_(50)分别为其亲代系的13.1及11.7倍,对伯喹的抗性为2.9倍,对氯喹未见明显交叉抗性。     

伯氏鼠疟原虫(Plasmodium berghei)对咯萘啶抗药性的研究

用本所传代已二十余年、对药物敏感的伯氏鼠疟原虫作种源,每转种一代给小白鼠口服单次量咯萘啶。第1代剂量为8 mg/kg,其后剂量每代增加2 mg/kg。转种至第23代,剂量达2,400mg/kg时,虽部分小鼠死亡,存活小鼠的原虫血症仍不转阴,此时原虫的抗药性为亲代原虫的300倍以上。抗咯萘啶鼠疟原虫(RPB₂)对氯喹、喹哌、吡咯喹、M-6407、阿的平与青蒿素等有一定程度的交叉抗药性。用对亲代原虫有效量的3～10倍治疗RPB₂原虫时,不能使原虫血症转阴。如不再用药,连续转种5代,RPB₂可恢复对咯萘啶的敏感性。     

双氢青蒿素对小鼠抗疟作用的药效动力学

双氢青蒿素(DHA)是青蒿素的一种还原产物,对感染伯氏疟原虫ANKA株的小鼠一次im给药,其抗疟作用的量—效关系和时—效关系可分别用y=4.9960+2.9536x和y=7.2654-0.3414t表达,进而估算出其ED₅₀和ED₅₀分别为1.00±0.13 mg/kg和2.72±0.70 mg/kg以DHA 5.0 mg/kg im后其药效下降一半的时间为6.6 h,体内有效药量的消除速率常数k为0.2662 h^-1,效量半衰期为2.6 h。式中y为机率单位,是DHA对疟原虫抑制作用的估算值,x为对数剂量,t为DHA im后的间隔时间。     

莨菪碱衍生物与M胆碱受体相互作用的构效关系

本文研究了一系列东莨菪碱衍生物对³H-QNB与大鼠脑M受体特异结合的影响。并通过比较它们的IC₅₀(用结合实验),药物—受体相互作用的解离常数K_B(抗乙酰胆碱引起的回肠收缩)以及抗震颤和抗匹罗卡品引起小鼠流涎的ED₅₀,分析了它们的构效关系。结果表明,K_B值与IC₅₀有很好的相关性(r=0.977),其线性回归的斜率为1.047;IC₅₀与抗震颤作用的ED₅₀之间相关性差,而log IC₅₀/ED₅₀值与它们的分配系数(logP)相关好(r=0.971),10号化合物的分配系数最大,中枢作用的选择性也最强。抗流涎ED₅₀与IC₅₀的相关系数为0.827。     

三氟甲基氨酚喹类似物的合成及其抗疟活性

本文报道了22个7-三氟甲基和2-甲基-7-三氟甲基氨酚喹类似物的合成。用伯氏疟原虫(plasmodium berghei)ANKA正常株感染小鼠作抑制性治疗试验,在剂量为(10 mg/kg)/d×4和(20 mg/kg)/d×4时,有11个化合物(Ⅰ_1～9,Ⅱ₃和Ⅱ₆)对疟原虫完全抑制。其中3个化合物(Ⅰ₂,Ⅰ₆和Ⅰ₇)在剂量为(5 mg/kg)/d×4时,就能对原虫完全抑制。12个化合物(Ⅰ_1～10,Ⅱ₃和Ⅱ₆)用伯氏疟原虫ANKA抗氯喹株感染小鼠作治疗试验,剂量为(20 mg/kg)/d×4,2个化合物(Ⅰ₄和Ⅱ₃)在受试的5只小鼠中,原虫完全被抑制的鼠分别为3和4只,用相同剂量的对照药物盐酸氨酚喹治疗,原虫仍为阳性。     

2,4-二氨基-6-取代氨基磺酰喹唑啉类化合物抗鼠疟作用的研究

用伯氏鼠疟模型筛选了17个2,4-二氨基-6-取代氨基磺酰喹唑啉类化合物。初步结果显示,化合物Ⅰ₄,Ⅰ₅,Ⅰ₁₀,Ⅰ₁₁和Ⅰ₁₂口服有较好抗疟作用,对正常敏感株(N)的SD₅₀为0.43～2.4mg/kg×4d,高度抗氯喹株(RC)为0.19～0.42mg/kg×4d,(NK₆₅)株为7.2～100mg/kg×4d,抗磺胺株(ORA)为11～76 mg/kg×4d。上述结果表明,该类化合物对(RC)株的疗效显著优于(N)株,但对(NK₆₅)株的疗效较差,与磺胺类药物有轻度交叉抗性。     

二氢青蒿素与青蒿琥酯的抗孕作用

研究表明,二氢青蒿素与青蒿琥酯对小鼠、金黄地鼠、豚鼠及兔均有抗孕作用。在金黄地鼠和豚鼠表现为引致流产,在小鼠和兔表现为使胚胎吸收。小鼠妊娠d7、金黄地鼠妊娠d5单次sc二氢青蒿素的抗孕ED₅₀(95%可信限)分别为32.8(27.7～38.9)及6.1(5.6～6.7)mg·kg^-1,豚鼠妊娠d18单次im二氢青蒿素的抗孕ED₅₀为18.3(13.9～24.2)mg·kg^-1,。金黄地鼠妊娠d5单次sc青蒿琥酯的抗孕ED₅₀为12.2(10.3～14.4)mg.kg^-1.以金黄地鼠进行的观察表明二氢青蒿素对胚胎有较高的选择性作用,引起胚胎坏死的剂量对于母体子宫、卵巢和一般健康状况无明显损害。     

补血益母丸哺乳期暴露对大鼠亲代和子代发育毒性的研究

目的 观察补血益母丸对哺乳期的亲代母鼠及子代生长发育的影响,探讨其安全性。方法 妊娠大鼠100只,随机分为4组,即对照组（去离子水）和补血益母丸低、中、高剂量（3.8、11.4、34.2 g生药/kg）组,每组25只。F₀母鼠于哺乳期第0天开始ig给药,连续给药至哺乳期结束,每日l次。F₀母鼠观察一般状况、体质量、摄食量、分娩及哺乳情况;F1代大鼠观察仔鼠的外观、体质量、生理发育、神经反射、行为及生殖功能等。结果 未发现补血益母丸对F₀母鼠哺乳期以及胚胎和F1代大鼠生长发育有明显毒性和干扰作用。结论 补血益母丸对F₀代母鼠哺乳期及F1子代均无明显毒性,未见毒性反应的剂量（NOAEL）为34.2 g生药/kg,相当于临床人用剂量的53倍。     

静脉注射利多卡因对丙泊酚麻醉下阿芬太尼抑制人流手术患者体动反应的半数有效剂量的影响

目的 研究静脉注射利多卡因对丙泊酚麻醉下阿芬太尼抑制人流手术患者体动反应的半数有效剂量（ED₅₀）的影响。方法 择期人工流产手术患者，年龄18~40岁，美国麻醉医师协会分级I~II级。随机分成2组，利多卡因联合阿芬太尼组（LA组）与阿芬太尼组（A组）。LA组患者静脉注射利多卡因1.0 mg·kg^-1后，缓慢注射丙泊酚2.0 mg·kg^-1及阿芬太尼（初始剂量为15.5 μg·kg^-1），A组患者则静脉注射0.1 mL·kg^-1生理盐水后，再依次缓慢注射丙泊酚2.0 mg·kg^-1与阿芬太尼。待患者意识消失后，消毒铺巾，观察患者置入宫颈探条的体动反应。采用序贯法计算阿芬太尼的剂量，若在置入宫腔探条时，发生体动阳性反应，则下一例患者剂量增加20%，反之则剂量降低20%。直至出现 ≥ 6个阳性反应和阴性反应的交替点，结束试验。采用概率单位回归分析法计算阿芬太尼抑制人流患者体动反应的ED₅₀、95%有效剂量（ED₉₅）及其95%可信区间（CI），记录术中生命体征，静脉注射痛，术后10 min、术后30 min、出院时疼痛评分及不良反应等指标。结果 LA组ED₅₀为6.55 μg·kg^-1（95%CI，2.10~8.07 μg·kg^-1），A组ED₅₀为8.24 μg·kg^-1（95%CI，6.75~9.75 μg·kg^-1），2组阿芬太尼的ED₅₀有差异；与A组比较，LA组术后10 min、术后30 min、出院时疼痛评分更低，差异有统计学意义（P<0.000 1或P<0.05）；LA组静脉注射痛发生率下降（减少44.2%），差异有统计学意义（P<0.01）；2组呼吸抑制发生例数、清醒时间与恶心呕吐等比较差异无统计学意义。结论 静脉注射利多卡因可显著降低阿芬太尼用于人流手术的ED₅₀，减少静脉注射痛发生率，缓解术后短期急性疼痛。     

伯氏疟原虫ANKA株模型的建立及其在抗疟药筛选中的应用

本文报告伯氏疟原虫ANKA株—斯氏按蚊—小鼠(C₅₇BL或ICR/JCL)模型。实验证明,国内常用的6个品系(C₅₇BL,ICR/JCL,615,SMMC/B,SMMC/C和昆明系)小鼠对伯氏疟原虫ANKA株输血感染都很敏感;在一定条件下,42批斯氏按蚊对伯氏疟原虫ANKA株的腺感染率为38.0±4.8%。子孢子腹腔接种后,以C₅₇BL和ICR/JCL小鼠最为敏感,且感染后小鼠平均存活20天左右。这一虫株对氯喹、甲氟喹、伯喹、乙胺嘧啶等都敏感,能正确反映常用抗疟药物的病因性预防作用和红细胞内持效作用。     

伯氏疟原虫K173株对喹哌抗药性的实验研究

用小剂量递增法培育伯氏疟原虫对喹哌的抗药性,起始剂量7 mg/kg×1,每传三代递增3.5 mg/kg,至20代,历时5个多月,培育出对喹哌有110倍以上抗性的虫系。抗喹哌伯氏疟原虫系对羟基喹哌、甲氟喹、青蒿酯、青蒿素都有明显的交叉抗性,对咯萘啶、氯喹和伯喹仅有微弱交叉抗性;对乙胺嘧啶和硝喹显示高敏效应。但该虫系的抗性尚不稳定,停药后连续血传12代,抗性水平由110多倍降至8倍.     

Differential cytotoxic effects of docetaxel in a range of mammalian tumor cell lines and certain drug resistant sublinesin vitro

Thein vitro cytotoxic effects of docetaxel (Taxotere^®; RP56976, NSC688503) proved both time and concentration dependent. Amongst thirteen human cell lines from various tumor types, exposure to increasing concentrations of docetaxel over 24 hrs resulted in a plateau-shaped dose response curve, suggesting that increased cell kill becomes more dependent on increased exposure duration than on concentration. IC₅₀ concentrations (reducing survival by 50%) ranged from 0.13–3.3 ng/ml, with three neuroblastoma lines proving most sensitive and three breast and two colon carcinoma lines showing least sensitivity. There was significant cross-resistance to docetaxel in the classic multidrug resistant (MDR) Chinese hamster ovarian (CHO) CHRC5 line and the human lymphoblastoid CCRF-CEMVLB1000 line, as well as in two vincristine(VCR)-selected MDR MCF-7 sublines. All four of these MDR sublines overexpress P-glycoprotein (Pgp), as did a 6fold docetaxel-selected resistant CHO subline. As an apparent corollary, in two human teratoma lines selected for etoposide resistance and showing some cross-resistance to VCR and in two CHO sublines expressing low levels of VCR resistance, yet all proving Pgp positive, no docetaxel crossresistance was identified. Verapamil modulated docetaxel resistance only in sublines expressing resistance to the drug and overexpressing Pgp. Four other human tumor sublines selected for resistance to 5-fluorouracil, cisplatin or teniposide, showed a lack of cross-resistance to docetaxel. Furthermore, cross-resistance to docetaxel was not apparant in four epipodophyllotoxin-selected resistant sublines with alterations in topoisomerase II, indicating its effectiveness against tumor cells expressing the topoisomerase II-related MDR phenotype. Our observation that docetaxel cross-resistance was not automatically expressed by classic MDR tumour cells appears of interest and of potential clinical relevance.     

Autoinduction of phase I and phase II metabolism of artemisinin in rats

1. This study was designed to get the direct evidence of the autoinduction metabolism for the antimalarial drug artemisinin (QHS). The sex effect on the pharmacokinetic profiles of QHS and its metabolites was also studied.

2. Two groups of rats received a single oral dose of QHS, and another two groups of rats were given oral doses of QHS once daily for 5 consecutive days. Plasma samples and its phase I and phase II metabolites were analysed for QHS, using a validated liquid chromatography tandem mass spectrometric (LC-MS) method.

3. Eight phase I metabolites (DQHS, M1–M7) and five phase II metabolites (M8–M12) of QHS were detected in rat plasma. The AUC_0?t of the parent drug QHS, and its phase I metabolites DQHS, M2, M3 and M6 decreased significantly (p?<?0.05) with increased oral clearance (CL/F) (p?<?0.05) after 5-day oral doses of QHS to rats. There was no change (p?>?0.05) in AUC of M1 and M4, whereas its metabolites M5 and M7 exhibited higher AUC (p?<?0.05). The AUC of phase II metabolites M8, M11 and M12 also increased after multiple oral doses of QHS. Sex difference was observed for QHS and its metabolites DQHS, M1, M3, M5, M8 and M9 in rats after a single oral dose of QHS.

4. The results gave the direct evidence for the autoinduction of both phase I and phase II metabolism of QHS. The sex effect existed for QHS.

     

伯氏疟原虫K173株对喹哌抗药性的实验研究

用小剂量递增法培育伯氏疟原虫对喹哌的抗药性,起始剂量7 mg/kg×1,每传三代递增3.5 mg/kg,至20代,历时5个多月,培育出对喹哌有110倍以上抗性的虫系。抗喹哌伯氏疟原虫系对羟基喹哌、甲氟喹、青蒿酯、青蒿素都有明显的交叉抗性,对咯萘啶、氯喹和伯喹仅有微弱交叉抗性;对乙胺嘧啶和硝喹显示高敏效应。但该虫系的抗性尚不稳定,停药后连续血传12代,抗性水平由110多倍降至8倍.     

Activity of tricyclic nucleoside 5′-phosphate in model systems of human ovarian cancer

Tricyclic nucleoside 5-phosphate (TCN-P) was evaluated in two models of human ovarian cancer. TCN-P reduced both colony number and volume in clonogenic assays employing human ovarian cancer cell lines. TCN-P cytotoxicity depended on the concentration, exposure duration and cell line studied, but not on cell line plating efficiency or growth rate in soft agarose. Comparison of experimental IC₅₀ concentrations for 1 hour or continuous TCN-P exposure with reported clinically relevant concentrations suggests that therapeutic TCN-P levels are more likely to be achieved by continuous infusions. Cell lines and sublines with resistance to several standard chemotherapeutic agents acquired both in vivo and in vitro were at most 2.6-fold cross-resistant to TCN-P with 1 hour drug exposure. Cross-resistance was not evident with continuous TCN-P exposure. Intermittent bolus TCN-P (100 mg/kg/d × 5) was ineffective in an in vivo xenograft model of human ovarian cancer. These data suggest that TCN-P is most likely to be clinically effective against ovarian cancer, and may be non-cross-resistant with several standard agents, if administered by continuous infusion. Preclinical evaluation of new agents, such as TCN-P, in these experimental models may provide information useful in subsequent clinical trials.Abbreviations CRI cross-resistance index - EGF epidermal growth factor - IC₅₀ drug concentration causing 50% inhibition of colony formation - LD₁₀ lethal dose in 10% of animals - NS normal saline - r correlation coefficient - RCV relative colony volume - RPMI Roswell Park Memorial Institute - SF surviving fraction - TCN tricyclic nucleoside - TCN-P tricyclic nucleoside 5-phosphate     

Effects of the atrial antiarrhythmic drug AVE0118 on cardiac ion channels

Previous studies in pigs and goats have demonstrated that AVE0118 prolongs atrial refractoriness without any effect on the QT-interval. The purpose of the present study was to investigate the effect of the compound on various cardiac ion channels. AVE0118 blocked the pig Kv1.5 and the human Kv1.5 expressed in Xenopus oocytes with IC₅₀ values of 5.4±0.7 M and 6.2±0.4 M respectively. In Chinese hamster ovary (CHO) cells, AVE0118 decreased the steady-state hKv1.5 current with an IC₅₀ of 1.1±0.2 M. The hKv4.3/KChIP2.2 current in CHO cells was blocked by AVE0118 by accelerating the apparent time-constant of inactivation (_inact), and the integral current was inhibited with an IC₅₀ of 3.4±0.5 M. At 10 M AVE0118 _inact decreased from 9.3±0.6 ms (n=8, control) to 3.0±0.3 ms (n=8). The K_ACh current was investigated in isolated pig atrial myocytes by application of 10 M carbachol. At a clamp potential of –100 mV the I_KACh was half-maximally blocked by 4.5±1.6 M AVE0118. In the absence of carbachol, AVE0118 had no effect on the inward current recorded at –100 mV. Effects on the I_Kr current were investigated on HERG channels expressed in CHO cells. AVE0118 blocked this current half-maximally at approximately 10 M. Comparable results were obtained in isolated guinea pig ventricular myocytes, where half-maximal inhibition of the I_Kr tail current occurred at a similar concentration of AVE0118. Other ionic currents, like the I_Ks, I_KATP (recorded in guinea pig ventricular myocytes), and L-type Ca²⁺ (recorded in pig atrial myocytes) were blocked by 10 M AVE0118 by 10±3% (n=6), 28±7% (n=4), and 22±13% (n=5) respectively. In summary, AVE0118 preferentially inhibits the atrial K⁺ channels I_Kur, I_to and I_KACH. This profile may explain the selective prolongation of atrial refractoriness described previously in pigs and goats.     

Studies with a 2,4-diamino-5-(3',4'-dichlorophenyl)-6-methylpyrimidine (DDMP)-resistant L1210 leukemia cell line without cross-resistance to methotrexate

An L1210 leukemia cell line resistant to 2,4-diamino-5-(3',4'-dichlorophenyl)-6-methylpyrimidine (DDMP) (L1210/DDMP) was developed in vivo by treatment of tumor-bearing mice. Resistance to DDMP was confirmed by subsequent in vivo survival experiments and by in vitro dose-response curves. The L1210/DDMP line demonstrated little cross-resistance to another folate analog, methotrexate (MTX). This was confirmed both in vivo, with survival experiments, and in vitro, using dose-response curves. A statistical analysis of the in vivo data confirmed DDMP resistance with lack of MTX cross-resistance. Dihydrofolate reductase (DHFR) activity in the L1210/DDMP/R₅ line was no greater than in the parent cell line (L1210/S). and the K_m of DHFR for dihydrofolate was the same in the L1210/DDMP/R₅ and L1210/S lines. The K_i for DHFR of the L1210/DDMP/R₅ cell line versus the L1210/S cell line was increased 3.0-fold for MTX and 3.5-fold for DDMP. Total accumulation of [¹⁴C]DDMP was identical in the two cell lines. The explanation for the lack of MTX cross-resistance in the L1210/DDMP/R₅ line is unknown.