Regulation of a hybrid gene by glucose and temperature in hamster fibroblasts   总被引：5，自引：0，他引：5  

J W Attenello  A S Lee 《Science (New York, N.Y.)》1984,226(4671):187-190

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A substance P antagonist, [D-Pro2, D-Trp7,9]SP, inhibits inflammatory responses in the rabbit eye   总被引：6，自引：0，他引：6  

G Holmdahl  R H?kanson  S Leander  S Rosell  K Folkers  F Sundler 《Science (New York, N.Y.)》1981,214(4524):1029-1031

Neurogenic factors released by antidromic nerve stimulation are thought to be in part responsible for the vasodilation and breakdown of the blood-aqueous barrier that follows trauma to the eye. Substance P is one candidate for the mediation of the inflammatory response since it is thought to be a neurotransmitter in sensory afferents and since exogenous substance P is capable of eliciting a response characteristic of inflammation. In rabbits, intravitreal or topical application onto the eye of a specific substance P antagonist, [d-Pro2, D-Trp7,9]SP, inhibited not only the irritant effects of exogenous substance P but also the inflammatory response to a standardized trauma (infrared irradiation of the iris). These observations suggest that substance P, or a related peptide, is a neurogenic mediator of the inflammatory response in the eye.  相似文献   

Science in the former soviet union     

Lee MS 《Science (New York, N.Y.)》1994,265(5168):13-14

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Growth of diamond from atomic hydrogen and a supersonic free jet of methyl radicals     

Lee SS  Minsek DW  Vestyck DJ  Chen P 《Science (New York, N.Y.)》1994,263(5153):1596-1598

The growth of small ( approximately 10-micrometer) diamond particles (on 0.1-or 0.25-micrometer seed crystals) using an effusive glow discharge nozzle for H.and a separate supersonic pyrolysis jet for .CH(3) is reported. Laser micro-Raman, scanning electron microscopy, and x-ray photoelectron spectroscopy data are presented as evidence that well-crystallized diamond is indeed formed. Resonant multiphoton ionization spectroscopy is used as a diagnostic for the gas-phase chemistry indicating that the radical sources are clean and quantitative and that there is no detectable interconversion of .CH(3) to C(2)H(2) under the conditions of the experiment. Diamond growth is found at substrate temperatures greater than or equal to 650 degrees C with no marked increase in the rate of growth up to 850 degrees C. Acetylene does not give good quality diamond under similar conditions.  相似文献   

草鱼、鲢、鳙秋繁及其对次年春繁的影响   总被引：1，自引：0，他引：1  

徐庆登  张成安  孙桂尧  刘才兆  钱 《上海水产大学学报》1993,(Z1)

1991年秋催产草鱼、鲂、鲢、鳙亲鱼256组,共获鱼苗5040万尾。平均催产率78.2%,受精率71.9%,孵化率75.4%。秋繁鱼苗当年可育成10cm以上鲢、鳙鱼种和8cm以上草鱼、鲂鱼种。鱼苗到鱼种成活率为37.2%。秋繁亲鱼次年春繁催产率、受精率和孵化率基本不受影响,产卵量比往年未秋繁者低6.8%～9.6%,卵径、卵粒重和鱼苗体长等无显著差异。草鱼、鲢、鳙卵母细胞发育不同步,春繁后经60天左右强化培育,卵巢中未成熟的卵母细胞可发育成熟。  相似文献   

Regulation by growth hormone of number of chondrocytes containing IGF-I in rat growth plate   总被引：12，自引：0，他引：12  

A Nilsson  J Isgaard  A Lindahl  A Dahlstr?m  A Skottner  O G Isaksson 《Science (New York, N.Y.)》1986,233(4763):571-574

Whether growth hormone stimulates longitudinal bone growth by a direct effect at the site of the growth plate or indirectly by increasing the concentration of circulating somatomedins (insulin-like growth factors) has been the subject of controversy. Immunohistochemical methods were used to explore the localization and distribution of insulin-like growth factor I (IGF-I) immunoreactivity in the epiphyseal growth plate of the proximal tibia of male rats. Cells in the proliferative zone of the growth plate of normal rats exhibited a bright immunofluorescence, whereas cells in the germinal and hypertrophic zones stained only weakly. In rats subjected to hypophysectomy, the number of fluorescent cells was markedly reduced. When the hypophysectomized rats were treated with growth hormone, either systemically or at the site of the growth plate, the number of IGF-I-immunoreactive cells in the proliferative zone was increased. The results show that IGF-I is produced in proliferative chondrocytes in the growth plate and that the number of IGF-I-containing cells is directly regulated by growth hormone. These findings suggest that IGF-I has a specific role in the clonal expansion of differentiated chondrocytes and exerts its function locally through autocrine or paracrine mechanisms.  相似文献   

Impaired immunoproteasome assembly and immune responses in PA28-/- mice     

Preckel T  Fung-Leung WP  Cai Z  Vitiello A  Salter-Cid L  Winqvist O  Wolfe TG  Von Herrath M  Angulo A  Ghazal P  Lee JD  Fourie AM  Wu Y  Pang J  Ngo K  Peterson PA  Früh K  Yang Y 《Science (New York, N.Y.)》1999,286(5447):2162-2165

In vitro PA28 binds and activates proteasomes. It is shown here that mice with a disrupted PA28b gene lack PA28a and PA28b polypeptides, demonstrating that PA28 functions as a hetero-oligomer in vivo. Processing of antigenic epitopes derived from exogenous or endogenous antigens is altered in PA28-/- mice. Cytotoxic T lymphocyte responses are impaired, and assembly of immunoproteasomes is greatly inhibited in mice lacking PA28. These results show that PA28 is necessary for immunoproteasome assembly and is required for efficient antigen processing, thus demonstrating the importance of PA28-mediated proteasome function in immune responses.  相似文献   

The social construction of production externalities in contemporary agriculture: Process <Emphasis Type="Italic">versus</Emphasis> product standards as the basis for defining “organic”     

B.?James?DeatonEmail author  John?P.?Hoehn 《Agriculture and Human Values》2005,22(1):31-38

The analysis distinguishes two types of standards for defining organic produce; process standards and product standards. Process standards define organic products by the method and means of production. Product standards define organic by the physical quality of the end product. The National Organic Program (NOP) uses process standards as the basis for defining organic. However, the situation is complicated by agricultural production practices, which sometimes result in the migration of NOP prohibited substances from conventional to organic fields. When this interaction alters the value of the product or the costs of production, a production externality is said to exist. Defining organic using process, rather than product standards, influences the burden and character of production externalities. The NOPs emphasis on process standards reduces the likelihood that production externalities will emerge.B. James Deaton is an Assistant Professor in the Department of Business and Agricultural Economics, University of Guelph, Canada. His research examines environmental and natural resource issues. He is particularly interested in the manner in which laws, rules, and standards influence environmental quality, natural resource use, and economic development. Additional research examines the relationship between different forms of private property and economic development, public support for various criteria used to preserve farmland, and the social construction of production externalities in agriculture. Prior to his PhD training, he worked on economic development projects in Lesotho (Southern Africa) and the Appalachian region of eastern Kentucky.John P. Hoehn is a Professor of Environmental and Natural Resource Economics in the Department of Agricultural Economics, Michigan State University. His teaching and research activities address environmental and natural resource policies, benefit-cost analysis of environmental improvements, methods for valuing non-market goods, improved institutions for protecting, managing, and using environmental resources, and the economics of ecological resources. He teaches core courses in the departmental and university-wide graduate programs in environmental and resource economics.  相似文献   

Climate impact of increasing atmospheric carbon dioxide   总被引：2，自引：0，他引：2  

Hansen J  Johnson D  Lacis A  Lebedeff S  Lee P  Rind D  Russell G 《Science (New York, N.Y.)》1981,213(4511):957-966

The global temperature rose by 0.2 degrees C between the middle 1960's and 1980, yielding a warming of 0.4 degrees C in the past century. This temperature increase is consistent with the calculated greenhouse effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean trend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980's. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.  相似文献   

THE DEVELOPMENT OF MORE EFFECTIVE DUST FUNGICIDES BY ADDING OXIDIZING AGENTS TO SULPHUR     

Lee HA  Martin JP 《Science (New York, N.Y.)》1927,66(1703):178

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