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排序方式: 共有1509条查询结果,搜索用时 15 毫秒
1.
Danail Hristozov Alex Zabeo Keld Alstrup Jensen Stefania Gottardo Panagiotis Isigonis Laura Maccalman 《Nanotoxicology》2016,10(9):1215-1228
Several tools to facilitate the risk assessment and management of manufactured nanomaterials (MN) have been developed. Most of them require input data on physicochemical properties, toxicity and scenario-specific exposure information. However, such data are yet not readily available, and tools that can handle data gaps in a structured way to ensure transparent risk analysis for industrial and regulatory decision making are needed. This paper proposes such a quantitative risk prioritisation tool, based on a multi-criteria decision analysis algorithm, which combines advanced exposure and dose-response modelling to calculate margins of exposure (MoE) for a number of MN in order to rank their occupational risks. We demonstrated the tool in a number of workplace exposure scenarios (ES) involving the production and handling of nanoscale titanium dioxide, zinc oxide (ZnO), silver and multi-walled carbon nanotubes. The results of this application demonstrated that bag/bin filling, manual un/loading and dumping of large amounts of dry powders led to high emissions, which resulted in high risk associated with these ES. The ZnO MN revealed considerable hazard potential in vivo, which significantly influenced the risk prioritisation results. In order to study how variations in the input data affect our results, we performed probabilistic Monte Carlo sensitivity/uncertainty analysis, which demonstrated that the performance of the proposed model is stable against changes in the exposure and hazard input variables. 相似文献
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目的:观察和探讨两种印模技术对单个前牙烤瓷冠颈缘外观的改善效果。方法:40位患者用简易印模技术制取印模,制作93件镍铬合金烤瓷瓷冠,设为实验组,另35位患者以常规印模技术制取印模,制作71件镍铬合金烤瓷瓷冠,设为对照组。观察两组戴冠当时与两年后的颈缘适合性、颜色、牙龈形态与健康情况。结果:试验组有98%的合金瓷冠具有优良的边缘适合性,仅2件(2%)出现颈缘黑线,与对照组相比有显著差异(P<0.05)。结论:简易印模技术能更好的保证工作区模型的准确度,从而有效地改善了镍铬合金烤瓷冠颈缘的美观与龈组织的健康。 相似文献
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Optimal surgery remains the mainstay of best outcome for rectal cancer. The demonstration, during the 3rd Annual Pelican Surgical Workshop Symposium, of an abdomino‐perineal excision (APE) performed in the ‘Berlin position’, further added to the debate on optimal surgical technique. Much interest was created at the 1st Pelican symposium with the demonstration, by the Swedish surgeon Dr Torbjorn Holm, of a prone APE and the delivery of a ‘cylindrical’ specimen and the potential to reduce local recurrence using this approach. The high rates of local recurrence following APE and the discussions as to optimal technique have led to the development of a proposed MERCURY Study Group study to assess the benefit of a radical APE, with careful assessment of the impact that this operation may have on morbidity. A German study has also been proposed adopting the UK's multidisciplinary team approach. It aims at targeting preoperative chemoradiotherapy at those patients in whom a radical APE or total mesorectal excision is likely to result in an involved surgical resection margin. In this article we review the evidence for improving the surgical technique for low rectal cancer. We believe improvements may be best achieved through continued European prospective, multi‐centre, multidisciplinary studies. 相似文献
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OBJECTIVE: Circumferential resection margin (CRM) involvement has been correlated with a high risk of developing local recurrence. The aim of this study was to examine the prognostic significance of the CRM involvement after curative resection of rectal cancer in patients treated with preoperative radiotherapy and postoperative chemotherapy where indicated. METHOD: All patients with rectal cancer treated in a regional central unit from 1996 to 2004 were identified. A surgical resection was performed on 257 patients, and in 229 of these this was assessed as potentially curative. The CRM was examined in all patients. A CRM of < or = 1 mm was considered positive. RESULTS: A positive margin was seen in 19 (8%) patients. At a median follow up of 40 months, only four (1.7%) patients had developed local recurrence, one of whom had a positive CRM. In the four patients the tumour was 5 cm or less from the anal verge. There were no significant differences regarding local recurrence and survival between CRM positive and negative tumours. CONCLUSION: Rectal cancer managed by combined radiochemotherapy and surgery resulted in a low positive CRM rate and a low local recurrence rate. An involved CRM was not a predictor of local recurrence. 相似文献
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Grace Montepiedra Ritesh Ramchandani Sachiko Miyahara Soyeon Kim 《Statistics in medicine》2021,40(2):327-348
When a new treatment regimen is expected to have comparable or slightly worse efficacy to that of the control regimen but has benefits in other domains such as safety and tolerability, a noninferiority (NI) trial may be appropriate but is fraught with difficulty in justifying an acceptable NI margin that is based on both clinical and statistical input. To overcome this, we propose to utilize composite risk‐benefit outcomes that combine elements from domains of importance (eg, efficacy, safety, and tolerability). The composite outcome itself may be analyzed using a superiority framework, or it can be used as a tool at the design stage of a NI trial for selecting an NI margin for efficacy that balances changes in risks and benefits. In the latter case, the choice of NI margin may be based on a novel quantity called the maximum allowable decrease in efficacy (MADE), defined as the marginal difference in efficacy between arms that would yield a null treatment effect for the composite outcome given an assumed distribution for the composite outcome. We observe that MADE: (1) is larger when the safety improvement for the experimental arm is larger, (2) depends on the association between the efficacy and safety outcomes, and (3) depends on the control arm efficacy rate. We use a numerical example for power comparisons between a superiority test for the composite outcome vs a noninferiority test for efficacy using the MADE as the NI margin, and apply the methods to a TB treatment trial. 相似文献
8.
目的 探讨胃肠道恶性肿瘤及其周围边组织中c -mycmRNA表达与手术切缘的安全性关系。方法 用RT -PCR方法检测了 12例胃癌和 16例肠癌标本肿瘤中心及周边组织中c-mycmRNA的表达。结果 肿瘤的各种分型与各个分期c -mycmRNA的表达无显著性差异。肿瘤周边组织中 ,距肿瘤边缘 4cm处c -mycmRNA表达率显著下降 (P <0 .0 5 ) ,距肿瘤边缘 5cm以远表达率为 0。结论 根据c -mycmRNA表达 ,距肿瘤边缘 5cm处可定为肿瘤较安全的切缘 相似文献
9.
肺癌术后支气管切缘癌发生的相关因素分析 总被引:2,自引:0,他引:2
目的 探讨肺癌术后支气管切缘癌发生的相关因素。方法 对 2 43例原发性非小细胞肺癌患者的病例资料进行回顾性分析 ,采用Logistic回归分析判断术后支气管切缘癌发生的相关因素。 结果 2 43例肺癌患者中 ,支气管切缘癌发生 3 1例 ,发生率为 12 .8% ,多因素分析显示 ,中央型肺癌、肺叶支气管淋巴结转移及组织学类型为鳞癌是支气管切缘癌发生的危险因素。结论 中央型肺癌、肺叶支气管淋巴结转移及组织学类型为鳞癌的肺癌病例应考虑发生术后支气管切缘癌的可能 相似文献
10.
目的探讨肺癌切除组织和支气管p53基因突变及端粒酶活性表达,并对肺癌切除后的效果进行了评价.方法用PCR-SSCP方法,检测60例肺癌和10例肺良性肿瘤手术切除标本的支气管切缘(切缘病理切片无癌细胞残留)的p53基因突变及端粒酶活性的表达.结果在60例肺癌中有16例(26.7%)肺癌支气管切缘和30例(50.0%)肺癌组织存在p53基因突变及端粒酶活性阳性表达.肺癌切除组织基因突变及端粒酶活性表达为小细胞癌(100%)最高,次为鳞癌(70%)、腺鳞癌(60%)、腺癌(40%).p53基因突变及端粒酶活性表达与TNM分期有关.Ⅲ期(72.7%)最高,其次为Ⅱ期(58.3%),Ⅰ期(25.5%).术后随访3~8个月支气管切缘p53基因突变及端粒酶活性表达,10例(62.5%)发生支气管残端复发转移.而p53及端粒酶阴性者术后无残端癌复发.肺癌组织p53及端粒酶阳者中有20例(66.7%)在随访中发现癌复发转移,而p53及端粒酶阴性者中未发现癌复发转移.结论检测支气管切缘p53基因突变及端粒酶活性表达,作为肺癌切除后的"分子边界",可作为早期预测肺癌术后残端复发重要依据. 相似文献