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71.

Background

Quantiles are a staple of epidemiologic research: in contemporary epidemiologic practice, continuous variables are typically categorized into tertiles, quartiles and quintiles as a means to illustrate the relationship between a continuous exposure and a binary outcome.

Discussion

In this paper we argue that this approach is highly problematic and present several potential alternatives. We also discuss the perceived drawbacks of these newer statistical methods and the possible reasons for their slow adoption by epidemiologists.

Summary

The use of quantiles is often inadequate for epidemiologic research with continuous variables.  相似文献   
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Tissue microarrays (TMAs) represent a powerful method for undertaking large‐scale tissue‐based biomarker studies. While TMAs offer several advantages, there are a number of issues specific to their use which need to be considered when employing this method. Given the investment in TMA‐based research, guidance on design and execution of experiments will be of benefit and should help researchers new to TMA‐based studies to avoid known pitfalls. Furthermore, a consensus on quality standards for TMA‐based experiments should improve the robustness and reproducibility of studies, thereby increasing the likelihood of identifying clinically useful biomarkers. In order to address these issues, the National Cancer Research Institute Biomarker and Imaging Clinical Studies Group organized a 1‐day TMA workshop held in Nottingham in May 2012. The document herein summarizes the conclusions from the workshop. It includes guidance and considerations on all aspects of TMA‐based research, including the pre‐analytical stages of experimental design, the analytical stages of data acquisition, and the postanalytical stages of data analysis. A checklist is presented which can be used both for planning a TMA experiment and interpreting the results of such an experiment. For studies of cancer biomarkers, this checklist could be used as a supplement to the REMARK guidelines.  相似文献   
74.
笔者在标本解剖操作观察腋窝结构时发现1例左侧腋动脉与臂丛神经位置及走行出现变异,既往文献报道的变异多为腋动脉发出的分支与臂丛神经之间的位置与走行之间变异[1-3],本次解剖观察发现腋动脉与臂丛神经的内侧束、外侧束和后束之间的位置关系出现变异,与既往报道有所不同,现报告如下。  相似文献   
75.
Abstract

A Wada procedure was performed on a bilingual seizure surgery candidate. Immediately after the injection of barbiturate into the right internal carotid artery the patient spontaneously switched from counting in English (the language he indicated that he used most often) to Spanish (the language he learned first). He named in Spanish spontaneously as well. After injection of the left ICA the patient exhibited a global aphasia, with no evidence for differential recovery of language as the aphasia cleared. These observations are discussed in relation to the hypothesis that a language learned later in life may be more likely to be bilaterally represented than the first language learned.  相似文献   
76.
Between 1978 and 1981, 74 women with nonpalpable breast cancer underwent surgery after localization guides were placed. In 72 patients, guides were introduced parallel to the chest wall; in two the needle was positioned anteroposteriorly under computed tomographic guidance. Fifty-six cases (76%) were infiltrating cancer; 13 (17%), intraductal cancers; two (3%), inflammatory; and three (4%), lobular carcinoma in situ. Surgery was not used to treat the latter five patients. In the remaining 69 women, 42 (61%) were treated by means of modified radical mastectomy; six (9%), total mastectomy; 12 (17%), local excision and radiation therapy; and seven (10%), local excision alone; exact therapy for two women (3%) was unknown. At a minimum follow-up of 5 years, none of the 67 women in whom the parallel approach was used had a local recurrence. The authors conclude that preoperative placement of guides parallel to the chest wall does not appear to increase the risk of local breast cancer recurrence.  相似文献   
77.
Lynch  DA; Gamsu  G; Ray  CS; Aberle  DR 《Radiology》1988,169(3):603-607
In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.  相似文献   
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79.
目的研究MR氢质子波谱(^1H-MRS)成像在神经上皮组织肿瘤分级中的价值。方法52例颅内神经上皮组织肿瘤患者,低级别29例,高级别23例,均行MRI及^1H-MRS检查。结果52例中,Ⅱ级9例,Ⅲ级11例,Ⅳ级12例,将Ⅱ级列为低级别组,Ⅲ级、Ⅳ级为高级别组,脂质(Lip)[乳酸(Lac)]/肌酸(Cr)、Lip(Lac)/N-乙酰天门冬氨酸(NAA)、Lip(Lac)/胆碱化合物(Cho),Lip(Lac)在组间差异有统计学意义,低级别组各代谢物比值中位数分别为0.14、0.16、0.09、0.32,高级别组各代谢物中位数分别为1.64、1.24、0.87、1.68。Lip(Lac)/Cr≤0.425为低级别肿瘤,Lip(1ac)/Cr>0.425为高级别肿瘤,诊断敏感度、特异度、阳性予测值、阴性预测值分别为87.0%、96.6%、95.2%、90.3%。常规MR图像诊断肿瘤级别敏感度、特异度、阳性予测值、阴性预测值分别为87.0%、82.8%、80.0%、88.9%。结论^1H-MRS在神经上皮组织肿瘤分级中有一定的价值,常规MR图像结合MRS可明显提高诊断准确率。  相似文献   
80.
目的:检测急性非淋巴细胞白血病患者白血病细胞表面MHC—Ⅱ类分子和共刺激分子的表达情况。方法:采集骨髓中白血病细胞大于70%的27例初诊或复发息者骨髓细胞。荧光抗体标记。应用流式细胞仪进行HLA—DR、CD80(B7-1)和CI)和(B7—2)免疫标记检测。结果:27例病人除M3型表达明显低于其他各型外。HLA—DR抗原的表达均较高。其中M2型最高为90%;CD80阳性率很低,最高为M1型只有5%。其余均在l%~3%之间。CD86的表达高于CD80,最高为M5型为48%,最低为M6型为11%。结论:白血病细胞表面共刺激分子表达以CD80缺乏为主。  相似文献   
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