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.     

硝酸铋与丙磺舒合用对顺铂肾毒性的防护作用

毒性剂量的顺铂（ＣＰ３０μｍｏｌ·ｋｇ－１ｉｐ）可引起血尿素氮（ＢＵＮ）升高。硝酸铋（ＢＮ）５μｍｏｌ·ｋｇ－１于ＣＰ前４８和２４ｈｓｅ，丙磺舒（Ｐｒｏ）７００μｍｏｌ·ｋｇ－１于ＣＰ前１５，１ｈ及ＣＰ后５ｈｉｇ，或ＢＮ与Ｐｒｏ二者半量合用，按上述给药，均能抑制ＣＰ引起的ＢＵＮ升高，尤以ＢＮ＋Ｐｒｏ组抑制作用显著。肾脏光镜和电镜标本显示，ＣＰ使肾小管受损严重；ＢＮ组，Ｐｒｏ组和ＢＮ＋Ｐｒｏ组均使ＣＰ引起的肾小管受损减轻，尤以ＢＮ＋Ｐｒｏ组减轻明显。ＢＮ２．５－２０μｍｏｌ·ｋｇ－１剂量依赖性地诱导小鼠肾脏金属硫蛋白合成。Ｐｒｏ可使ＣＰ后２４ｂ肾铂含量明显降低；Ｐｒｏ或Ｐｒｏ＋ＢＮ使尿铂累积排出量增加，血浆铂浓度降低。提示ＰＦＯ防护ＣＰ肾毒性与其减少肾铂分布，增加尿铂排出有关。     

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。     

庚铂治疗晚期胃癌Ⅱ期临床研究

目的评价庚铂（cis-malonato platinum,Hetaplatin）单药和联合治疗晚期胃癌的安全性和有效性.方法多中心、开放式、前瞻性随机对照Ⅱ期临床研究;单药组：庚铂360 mg/m^2,第1天;庚铂联合氟尿嘧啶和亚叶酸钙（5-FU/CF）试验组：庚铂用法同单药组,5-FU 375 mg/m^2静脉输注,第1～5天,CF 200 mg/m^2静脉输注,第1～5天;顺铂（DDP）联合5-FU/CF对照组：DDP 25 mg/m^2稀释于生理盐水500 ml,第1～3天,5-FU/CF用法同庚铂联合试验组.以上三个方案每3周重复一次,为一疗程.采用WHO实体瘤近期疗效标准评价,于第2个疗程后第三周进行疗效评价：采用加拿大国家癌症研究所CTG补充常用毒性标准评价安全性.结果 200例可评价疗效的患者中,庚铂单药组总有效率（CR＋PR）14.9%;庚铂联合试验组总有效率为22.8%;顺铂联合对照组总有效率为22.0%;两联合组疗效之间差异无显著性.在庚铂单药治疗组,血液学毒性轻微,非血液学毒性包括较严重的恶心、呕吐和食欲下降;庚铂联合试验组与DDP联合对照组相比,前者血液学不良反应低,而非血液学不良反应略高,但差异均无显著性.结论治疗晚期胃癌庚铂单药安全有效;庚铂加5-FU/CF联合治疗疗效与DDP加5-FU/CF相当;药物不良反应相似.     

Brain metastases as isolated site of relapse in patients with epithelial ovarian cancer previously treated with platinum and paclitaxel-based chemotherapy

Brain metastases in patients with epithelial ovarian cancer (EOC) have an estimated incidence of 0.3-1.9% and are isolated in up to 50% of these patients. The risk factors and the prognostic significance of isolated central nervous system (CNS) relapse in patients with EOC who received primary treatment with platinum and paclitaxel have not been identified. We conducted a retrospective study in patients with EOC who relapsed with isolated brain metastases and report our experience. Two hundred sixty-seven patients with stages III and IV EOC, in clinical complete remission after first-line treatment with platinum and paclitaxel, were included in our analysis. After a median follow-up of 65 months, 150 patients had relapsed. Eight patients (5%) had isolated brain metastases. Patient and disease characteristics did not differ among patients who relapsed with isolated brain metastases and those with relapse outside the CNS. Median time to first disease relapse, overall survival, and survival after relapse did not differ significantly between patients with brain metastases and those with relapse outside the CNS. Two patients have died 6 and 12 months after the diagnosis of brain metastases, and 5 patients are alive 4-35 months after the diagnosis of isolated brain metastases. Three patients remain free of disease 4-18 months after treatment with radiotherapy and systemic chemotherapy for their CNS metastatic disease. Patients with isolated brain metastases have comparable survival to patients with relapse outside the CNS, and long-term remission can be achieved in some cases, provided that systemic chemotherapy is added to local treatment.     

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。