Sequence-dependent Termination of Mammalian DNA Polymerase Reaction by a New Platinum Compound, (–)-(R)-2-Aminomethylpyrrolidine(1,1-cyclobutane-dicarboxylato)-2-platinum(II) Monohydrate

We examined the mechanisms of the inhibition of DNA synthesis by a new platinum compound, (-)-( R )-2-aminomethylpyrrolidine(1,1-cyclobutane-dicarboxylato)-2-platinum(II) monohydrate (DWA-2114R), a derivative of the antitumor drug cis- diamminedichloroplatinum(II) (CDDP), using prokaryotic and eukaryotic DNA polymerases. Preincubating activated DNA with CDDP or DWA-2114R reduced its template activity for prokaryotic and eukaryotic DNA polymerases in a dose-dependent manner. DWA2114R required six times greater drug concentration and two times longer incubation time to show the same decrease of the template activity compared to CDDP. Treatment of primed pUC118 ssDNA templates with the two drugs followed by second-strand synthesis by prokaryotic and eukaryotic DNA polymerases revealed that DWA2114R bound to DNA in a similar manner to CDDP and these adducts blocked DNA elongation by DNA polymerases of eukaryotes as well as of prokaryotes. With these two drugs, the elongations by E. coli DNA polymerase I (Klenow fragment), T7 DNA polymerase and calf thymus DNA polymerase α were strongly arrested at guanine-guanine sequences (GG). Stop bands were also observed at adenine-guanine sequences (AG) guanine-adenine-guanine sequences (GAG) and mono-guanine sequence (G). Calf testis DNA polymerase β was also arrested efficiently at AG, GAG and G, but much more weakly at GG. This pattern was common to DWA2114R and CDDP.     

Do Electrode and Lead Design Differences for Permanent Cardiac Pacing Translate into Clinically Demonstrable Differences? (Comparison of Sintered Platinum and Activated Vitreous and Porous Carbon Electrodes)

A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs--sintered platinum, vitreous carbon, and porous carbon. Ninety-nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of the native endocardial electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25-1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six-month thresholds for the S80, 423S, and S100 leads were 1.18 +/- 0.35, 1.17 +/- 0.29, and 1.06 +/- 0.38 V respectively at 0.5 msec pulse duration. Differences between 'high performance' pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinical advantage to patients.     

Early effects of cis-dichlorodiammine platinum (II) on tumor progression and programmed death of Ehrlich ascites carcinoma cells

We studied the effects of cis-dichlorodiammine platinum (II) on different pathways of cell death in cultured Ehrlich ascites carcinoma in vitro and on subsequent growth of transplanted tumor in vivo. One-hour incubation with the cytostatic modulated apoptosis in cell culture. However, exposure of cell culture to a minimal effective concentration of cis-platinum(II)diammine dichloride promoted the growth of transplanted tumor.     

Addition of platinum compounds to a new agent in patients with advanced non-small-cell lung cancer: a literature based meta-analysis of randomised trials.

BACKGROUND: Single new agents reportedly produce promising response and survival effects, but platinum-based doublets remain the standard chemotherapy for advanced non-small-cell lung cancer (NSCLC). The aim of this study was to evaluate the effectiveness of platinum for advanced NSCLC by carrying out a meta-analysis of trials that compared platinum-based doublets with single new agent therapy alone. METHODS: We carried out a literature search to identify trials, conducted between 1994 and 2003, comparing a doublet of platinum plus a new agent with a new agent alone in previously untreated patients with advanced NSCLC. Outcomes analysed were response, survival and toxicity. RESULTS: Eight trials encompassing 2374 patients were identified. Platinum-based doublets produced an approximately two-fold higher overall (complete and partial) response rate than the new agent alone [odds ratio = 2.32; 95% confidence interval (CI)=1.68-3.20]. Platinum-based doublet therapy was also associated with a 13% prolongation of survival (hazard ratio = 0.87; 95% CI = 0.80-0.94, P <0.001). Despite significant increases in the frequencies of various toxic effects in patients receiving platinum-based doublets, no significant difference in treatment-related mortality was observed. CONCLUSION: This is the first published meta-analysis demonstrating the importance of combining platinum with single new agents in the treatment of advanced NSCLC.     

铂类的耳毒性

铂类化合物的耳毒性具有初期症状隐匿 ,不可逆性和严重影响生活质量等特点 ,逐渐为临床医师所关注。该文对其发病情况 ,病理学改变 ,临床特征和防治措施等加以综述。     

Randomized phase II trial of carboplatin versus paclitaxel and carboplatin in platinum-sensitive recurrent advanced ovarian carcinoma: a GEICO (Grupo Espanol de Investigacion en Cancer de Ovario) study.

BACKGROUND: The aim of this study was to determine whether the response rate for the paclitaxel-carboplatin combination is superior to carboplatin alone in the treatment of patients with platinum-sensitive recurrent ovarian carcinoma. PATIENTS AND METHODS: Patients with recurrent ovarian carcinoma, 6 months after treatment with a platinum-based regimen and with no more than two previous chemotherapy lines, were randomized to receive carboplatin area under the curve (AUC) 5 (arm A) or paclitaxel 175 mg/m(2) + carboplatin AUC 5 (arm B). The primary end point was objective response, following a 'pick up the winner' design. Secondary end points included time to progression (TTP), overall survival, tolerability and quality of life (QoL). RESULTS: Eighty-one patients were randomized and included in the intention-to-treat analysis. The response rate in arm B was 75.6% [26.8% complete response (CR) + 48.8% partial response (PR)] [95% confidence interval (CI) 59.7% to 87.6%] and 50% in arm A (20% CR + 30% PR) (95% CI 33.8% to 66.2%). No significant differences were observed in grade 3-4 hematological toxicity. Conversely, mucositis, myalgia/arthralgia and peripheral neurophaty were more frequent in arm B. Median TTP was 49.1 weeks in arm B (95% CI 36.9-61.3) and 33.7 weeks in arm A (95% CI 25.8-41.5). No significant differences were found in the QoL analysis. CONCLUSIONS: Paclitaxel-carboplatin combination is a tolerable regimen with a higher response rate than carboplatin monotherapy in platinum-sensitive recurrent ovarian carcinoma.     

CKMT1A对人鼻咽癌HONE1细胞铂类化疗药物敏感性的影响及机制研究

近年来鼻咽癌患者五年生存率的提升难度明显增加,对铂类化疗药物的敏感性较差是主要原因,探讨耐药机制具有重要意义。本研究将鼻咽癌细胞转染分为空载体对照组(空载体质粒)、线粒体肌酸激酶1A(CKMT1A)过表达组(CKMT1A过表达载体质粒),分别进行MTT法检测、流式细胞术检测、实时荧光定量PCR检测和Western blot检测。结果显示随着顺铂浓度的增加,CKMT1A过表达组吸光度值下降幅度更明显(P<0.01)。根据顺铂IC₅₀结果选取2 μmol/L顺铂处理细胞24 h后,两组细胞均表现为G0/G1期比例明显下降,S期和G2/M期比例明显增多。2 μmol/L顺铂处理细胞48 h后,CKMT1A过表达组细胞凋亡率明显高于空载体对照组(P<0.01);CKMT1A过表达组c-PARP、Bax相对表达量明显高于空载体对照组,BCL-2相对表达量明显低于空载体对照组(P<0.05)。2 μmol/L顺铂处理细胞6 h后, CKMT1A过表达组p-STAT3相对表达量明显高于空载体对照组(P<0.01)。过表达CKMT1A可通过细胞凋亡信号通路下调STAT3磷酸化水平,抑制靶基因表达,促进人鼻咽癌细胞株HONE1凋亡,提升对铂类化疗药物的敏感性。     

洛铂与替加氟联合贝伐单抗治疗晚期大肠癌的临床研究

目的探讨洛铂与替加氟注射液（方克）联合贝伐单抗治疗晚期大肠癌的临床疗效及毒副反应。方法64例晚期大肠癌患者分别接受方案A（32例）、方案B（32例）治疗。方案A组：替加氟800 mg/m2,CIV（24 h）,d1-d5;LV200 mg/m2,静脉滴注（2 h）,d1~d5;洛铂35 mg/m2,静脉滴注,d1。方案B组：替加氟800 mg/m2,CIV（24 h）d1~d5;LV200 mg/m2,静脉滴注（2 h）,d1~d5,洛铂35 mg/m2;静脉滴注,d1;贝伐单抗15 mg/kg,静脉滴注,d1。结果方案A组：CR 3例,PR 7例,有效率31.3%;方案B组：CR 6例,PR 12例,有效率为56.3%,静脉滴注,2组有效率比较,差异有显著性（χ2=4.0635,P=0.044）。2组均未出现明显肝、肾功能及心脏毒性反应。不良反应发生率比较,2组无统计学意义（P〉0.05）。结论洛铂与替加氟联合贝伐单抗是治疗晚期大肠癌安全有效的方案之一,能显著提高晚期患者的有效率,毒副作用可以耐受。     

口服铂类药物沙铂胶囊的Ⅰ期临床研究

目的:沙铂是第一个在体外被证实与顺铂有同样抗肿瘤活性的口服铂类药物。本剂量递增(20,40,70,80,100 m.gm-2.d-1)Ⅰ期临床研究目的是评价人体对沙铂胶囊的耐受性,确定其在人体的最大耐受剂量(MTD)。方法:共纳入21例晚期恶性肿瘤患者。所有患者均可进行安全性分析。给予口服沙铂胶囊,qd,连续5 d,每21 d重复。结果:MTD为100 m.gm-2.d-1,剂量限制性毒性为呕吐、腹泻和血小板下降。其他常见不良反应还包括白细胞下降、中性粒细胞下降、疲乏、蛋白尿。结论:推荐Ⅱ期临床给药剂量为80 m.gm-2.d-1,连用5 d,每28～35 d为1周期。     

顺铂、樟脑胺氯乙酸铂及碳铂对染色体损伤的比较

以CHL细胞为材料,比较了顺铂(DDP)、碳铂(JM 8)和樟脑胺氯乙酸铂(CCP)的细胞毒作用和对CHL细胞的染色体损伤。实验表明,这三种铂络合物都有较强的细胞毒作用,其中顺铂最强而CCP最弱。DDP,JM-8和CCP的IC~(90)(±SD)分别为0.68±0.21,4.4±0.6,10.8±1.5μmol/L。在微核及染色体畸变实验中,观察到在药物浓度小于或等于IC_(90)时,这三种化合物诱发的微核及染色体损伤相当,但药物浓度增加时,CCP所诱发的微核及染色体畸变均大于DDP而JM-8最轻。