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PE Sipila VJ Wiebe GB Hubbard SK Koester VD Emshoff JU Maenpaa GT Wurz RC Seymour MW DeGregorio 《Canadian Metallurgical Quarterly》1993,(15):2138-2144
The effects of long-term tamoxifen exposure on cell growth and cell cycle kinetics were compared between oestrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) cell lines. In the MCF-7 cell line, prolonged tamoxifen exposure (0.5 mumol/l for > 100 days) blocked cells in G0-G1 of the cell cycle, and slowed the doubling time of cells from 30 to 59 h. These effects corresponded to an increase in the cellular accumulation of tamoxifen over time [mean area under concentration curve (AUC) = 77.92 mumoles/10(6)/cells/day]. In contrast, in the MDA-MB-231 cell line, long-term tamoxifen exposure had no obvious effect on the doubling time, and reduced cellular tamoxifen accumulation (mean AUC = 50.50 mumoles/10(6)/cells/day) compared to the MCF-7 cells. Flow cytometric analysis of MDA-MB-231 cells demonstrated that a new tetraploid clone emerged following 56 days of tamoxifen exposure. Inoculation of the MDA-MB-231 tetraploid clone and MDA-MB-231 wildtype cells into the opposite flanks of athymic nude mice resulted in the rapid growth of tetraploid tumours. The tetraploid tumours maintained their ploidy following tamoxifen treatment for nine consecutive serial transplantations. Histological examination of the fifth transplant generation xenografts revealed that the tetraploid tumour had a 25-30 times greater mass, area of haemorrhage and necrosis, a slightly higher mitotic index and was more anaplastic than the control neoplasm. The control wildtype MDA-MB-231 tumours maintained a stable ploidy following tamoxifen treatment until the eighth and ninth transplantation, when a tetraploid population appeared, suggesting that tamoxifen treatment may select for this clone in vivo. These studies suggest that prolonged tamoxifen exposure may select for new, stable, fast growing cell clones in vitro as well as in vivo. 相似文献
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Fernanda R C Damasceno Denise M G Freire Magali C Cammarota 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(5):730-738
BACKGROUND: The application of lipase‐rich enzyme pools (such as the crude solid enzymatic preparation (SEP) obtained from Penicillium restrictum solid‐state fermentation of agro‐industrial wastes) to activated sludge systems may be an effective strategy for preventing various operational problems. The continuous addition of SEP to the treatment system can become cost‐prohibitive when in situ production and/or storage are factored in. The application of SEP to high‐fat wastewater treatment would only be justified as an emergency measure, such as a sudden increase in the fat content of the bioreactor influent. Therefore, the primary objective of this work was to investigate the efficiency of a crude SEP during fat shock loads, simulated through the periodic addition of dairy industry waste containing high fat concentrations to the feed stock of an activated sludge system, operated in continuous mode. RESULTS: The test bioreactor exhibited a higher average chemical oxygen demand (COD) removal efficiency than the control bioreactor (83% for control and 90% for test) and the fat accumulation in the biological flocs of the test bioreactor was 3.2 times lower than that in the control bioreactor. Turbidity was also lower in the effluent of the test bioreactor (123 and 66 FTU in control and test, respectively) and it had a shorter recovery time between shock loads, especially when the interval between loads was shorter than one month (biweekly and weekly shock loads). CONCLUSION: The addition of SEP during fat overloads in the reactor feed maintained efficient COD removal in the test bioreactor for 270 days without any operational problems. Copyright © 2008 Society of Chemical Industry 相似文献
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Advances in research on disability and rehabilitation are essential to creating equal opportunity, economic self-sufficiency, and full participation for persons with disabilities. Historically, such initiatives have focused on separate and specific areas, including neuroscience, molecular biology and genetics, gerontology, engineering and physical sciences, and social and behavioral sciences. Research on persons with disabilities should examine the broader context and trends of society that affect the total environment of persons with disabilities. This article examines the various disability paradigms across time, assessing the relative contribution of the socioecological perspective in guiding research designed to improve the lives of persons with disabilities. The authors recommend new research directions that include a focus on life span issues, biomedicine, biotechnology, the efficacy and effectiveness of current interventions, an emphasis on consumer-driven investigations within a socioecological perspective of disability, and the implications for research and practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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The purpose of the present study was to evaluate the accuracy of data regarding diagnoses of spinal disorders in administrative databases at eight different institutions. The records of 189 patients who had been managed for a disorder of the lumbar spine were independently reviewed by a physician who assigned the appropriate diagnostic codes according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). The age range of the 189 patients was seventeen to eighty-four years. The six major diagnostic categories studied were herniation of a lumbar disc, a previous operation on the lumbar spine, spinal stenosis, cauda equina syndrome, acquired spondylolisthesis, and congenital spondylolisthesis. The diagnostic codes assigned by the physician were compared with the codes that had been assigned during the ordinary course of events by personnel in the medical records department of each of the eight hospitals. The accuracy of coding was also compared among the eight hospitals, and it was found to vary depending on the diagnosis. Although there were both false-negative and false-positive codes at each institution, most errors were related to the low sensitivity of coding for previous spinal operations: only seventeen (28 per cent) of sixty-one such diagnoses were coded correctly. Other errors in coding were less frequent, but their implications for conclusions drawn from the information in administrative databases depend on the frequency of a diagnosis and its importance in an analysis. This study demonstrated that the accuracy of a diagnosis of a spinal disorder recorded in an administrative database varies according to the specific condition being evaluated. It is necessary to document the relative accuracy of specific ICD-9-CM diagnostic codes in order to improve the ability to validate the conclusions derived from investigations based on administrative databases. 相似文献
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SK Patterson JA Tworek MA Roubidoux MA Helvie HA Oberman 《Canadian Metallurgical Quarterly》1997,169(3):709-712
OBJECTIVE: The objective of this study was to describe the mammographic appearance with pathologic correlation of metaplastic carcinoma of the breast. CONCLUSION: Metaplastic carcinomas of the breast are masses with mammographic characteristics of low suspicion because of their histologic appearance. Metaplastic carcinoma should be included in the differential assessment of predominately circumscribed, noncalcified masses revealed on mammography. One salient feature that may distinguish metaplastic carcinomas is the occurrence of a circumscribed portion with a spiculated portion, which is seen in carcinomas that have a significant mixture of metaplastic and invasive carcinoma growth patterns. 相似文献