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Trajkovic K Hsu C Chiantia S Rajendran L Wenzel D Wieland F Schwille P Brügger B Simons M 《Science (New York, N.Y.)》2008,319(5867):1244-1247
Intraluminal vesicles of multivesicular endosomes are either sorted for cargo degradation into lysosomes or secreted as exosomes into the extracellular milieu. The mechanisms underlying the sorting of membrane into the different populations of intraluminal vesicles are unknown. Here, we find that cargo is segregated into distinct subdomains on the endosomal membrane and that the transfer of exosome-associated domains into the lumen of the endosome did not depend on the function of the ESCRT (endosomal sorting complex required for transport) machinery, but required the sphingolipid ceramide. Purified exosomes were enriched in ceramide, and the release of exosomes was reduced after the inhibition of neutral sphingomyelinases. These results establish a pathway in intraendosomal membrane transport and exosome formation. 相似文献
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Comparative analysis of 31 reference evapotranspiration methods under humid conditions 总被引：1，自引：0，他引：1
Evaluation of simple reference evapotranspiration (ETo) methods has received considerable attention in developing countries where the weather data needed to estimate ETo by the Penman–Monteith FAO 56 (PMF-56) model are often incomplete and/or not available. In this study, eight pan evaporation-based, seven temperature-based, four radiation-based and ten mass transfer-based methods were evaluated against the PMF-56 model in the humid climate of Iran, and the best and worst methods were selected from each group. In addition, two radiation-based methods for estimating ETo were derived using air temperature and solar radiation data based on the PMF-56 model as a reference. Among pan evaporation-based and temperature-based methods, the Snyder and Blaney–Criddle methods yielded the best ETo estimates. The ETo values obtained from the radiation-based equations developed here were better than those estimated by existing radiation-based methods. The Romanenko equation was the best model in estimating ETo among the mass transfer-based methods. Cross-comparison of the 31 tested methods showed that the five best methods as compared with the PMF-56 model were: the two radiation-based equations developed here, the temperature-based Blaney–Criddle and Hargreves-M4 equations and the Snyder pan evaporation-based equation. 相似文献
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Mammalian cells contain two related but unique isoforms of cyclooxygenase (COX-1 and COX-2). COX-1 is expressed constitutively in a majority of tissues and is involved in the production of prostaglandins (PGs) that modulate normal physiologic functions. COX-2 is inducible by various stimuli and is involved in the production of PGs that modulate physiologic events in development, cell growth, and inflammation. With the exception of peribronchial glands and chondrocytes of peribronchial cartilage, COX-2 is not detectable in the normal lung of nonhuman primates. We evaluated COX-2 expression by immunohistochemical methods in the inflammatory lesions of two cynomolgus monkeys (Macaca fascicularis) with acute severe pneumonia. Both monkeys exhibited acute severe bronchopneumonia; histologically, lung lesions were characterized by infiltration of large numbers of neutrophils and fewer macrophages, mild bronchial epithelial hyperplasia, and slight type-2 pneumocyte hyperplasia. In both monkeys, mild to marked COX-2 immunoreactivity was detected within the cytoplasm of macrophages, bronchial epithelial cells, type-2 pneumocytes, and endothelial cells of blood vessels. No COX-2 immunoreactivity was detectable in the neutrophils that constituted >90% of the inflammatory cells. These observations suggest that in acute inflammatory lung lesions in nonhuman primates 1) COX-2 is induced in the bronchial and alveolar epithelial cells, 2) macrophages are the primary inflammatory cells that exhibit COX-2, and 3) neutrophils do not express COX-2. 相似文献
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The FAO-56 Penman-Monteith combination equation (FAO-56 PM) has been recommended as the standard equation for estimating reference evapotranspiration (ET0). The FAO-56 PM equation requires the numerous weather data that are not available in the most of the stations. The main goal of this paper is to present the software for estimating reference evapotranspiration, focusing on the feature of using limited weather data. This is simple Windows-based and user-friendly software provides methods to estimate extra-terrestrial radiation, maximum sunshine hours, daily net radiation and daily/monthly ET0. The program is written in C# and includes comprehensive technical documentation. The software is available for free download.The weather data for this study were obtained from CIMIS for Davis weather station. The reduced-set FAO-56 PM approaches and adjusted Hargreaves equation were compared to the full-set FAO-56 PM equation. The FAO-56 reduced-set PM ET0 estimates were in closest agreement with FAO-56 full-set PM ET0 estimates. The adjusted Hargreaves equation (AHARG) was found to be in very good agreement with the full-set FAO-56 PM. This program is the first software facilitating calculation of ET0 only with air temperature parameter. 相似文献
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Expression of cyclooxygenase-2 in canine renal cell carcinoma 总被引：11，自引：0，他引：11
Cyclooxygenase-2 (COX-2) has been shown to be the primary enzyme responsible for prostaglandin production during inflammation but is absent in most tissues under normal physiological states. High levels of COX-2 expression have been observed in the macula densa and thick ascending limbs of fetal kidneys; this expression declines to minimal levels during renal maturation. We hypothesized that the neoplastic cells of renal cell carcinoma (RCC) may revert to high expression of COX-2, and we evaluated its expression in three spontaneous cases of canine RCC by using immunohistochemical methods. The neoplastic cells of two of the three cases exhibited moderate to marked COX-2 immunoreactivity. These results suggest that some canine renal cell carcinomas express high levels of COX-2, which may play a role in the modulation of neoplastic cell growth. 相似文献
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Software used for estimating reference evapotranspiration (ET0) has been developing in various directions. The main goal of this paper is to present an approach based on Service-Oriented Architecture (SOA) paradigm for modeling and estimating ET0. The FAO-56 Penman-Monteith (FAO-56 PM) and Hargreaves equation are used for estimating monthly ET0.The weather data for this study were obtained from CIMIS for Davis weather station. The FAO-56 PM and Hargreaves ET0 values estimated using ET Web service were compared to corresponding CIMIS PM ET0 estimates. The proposed model based on Web services implemented to the FAO-56 PM and Hargreaves equations has good performances and can be used in estimating ET0 and has ability to complete missing weather data. 相似文献
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