Differential effects of ethanol on prostaglandin responses of arterial and venous smooth muscle

Summary The present results, using isolated rat aortic strips and portal vein segments, demonstrate that ethanol, depending upon concentration, can either enhance or attenuate the contractile actions of PGF₂ on at least 2 different types of vascular smooth muscle. At the very least, the present findings question the use of ethanol as a solvent when investigating the contractile actions of PG molecules on smooth muscles.Supported by NIH grant No. HL-18015 and NIMH grant No. MH-26236. The authors are indebted to Dr.John E. Pike and Dr.John Babcock of the Upjohn Company for generously providing us with the PGF₂ used in this study.     

Holocene lake deposits of Bosten Lake, southern Xinjiang, China

A 9.25-m-long sediment core from Bosten Lake,Xinjiang, provides detailed information about changes in the water budget and biological acticity over the last 8400 cal-endar years. The chronology is constructed from six AMS radiocarbon dates on the terrestrial plant remains. Based onanalyses of TOC, CO3, detrital compounds and biogenic SiO2,lake level fluctuations and periods of remarkably-negative water budget appeared at 8.4-8.2 cal ka, 7.38-7.25 cal ka,5.7-5.5 cal ka, 3.7-3.4 cal ka and 3.3-2.9 cal ka, respec-tively. As they are in-phase with low lake levels at Sumxl Co and Bangong Co in western Tibet Plateau and with paleo-lakes in Inner Mongolia, a climate-induced change to some-what drier and warmer conditions is inferred. A further drop in lake level after 1320 AD of about 200 yr duration may heattributed to a negative water balance prior to the main phase of the Little Ice Age. Deep and stable lake phases of 1500 yr and 1800 yr duration at 7.2-5.7 cal ka and 5.5-3.7cal ka coincide with maximum moisture during the Holocene Megathermai in China. The long term trend towards aridity since about 4.3 cal ka can dearly be recognised. The reduced water budget of Bosten Lake from 640-1200 AD may be attributed to local effects.     

Splitting an Ordering into a Partition to Minimize Diameter

k consisting of k clusters, with k > 2. Bottom-up agglomerative approaches are also commonly used to construct partitions, and we discuss these in terms of worst-case performance for metric data sets. Our main contribution derives from a new restricted partition formulation that requires each cluster to be an interval of a given ordering of the objects being clustered. Dynamic programming can optimally split such an ordering into a partition P^k for a large class of objectives that includes min-diameter. We explore a variety of ordering heuristics and show that our algorithm, when combined with an appropriate ordering heuristic, outperforms traditional algorithms on both random and non-random data sets.     

人胰岛素原乳腺表达载体的构建

通过ＰＣＲ方法扩增了人胰岛素（ＨＩ）基因１．３４ｋｂ的ＤＮＡ片段并克隆于ｐＵＣ１８的ＳｍａⅠ位点内。经ＤＮＡ序列分析表明，该片段为ＨＩ基因的氨基酸编码区及３＇端调控区序列。同时，应用ＰＣＲ方法对牛α－乳白蛋白（ＢαＬＡ）基因进行了扩增，得到了０．８４ｋｂＤＮＡ扩增片段。将其克隆于去除了ＥｃｏＲＩ位点的ｐＵＣ１８ＳｍａＩ位点内，经内切酶分析和ＤＮＡ测序证明该片段是ＢαＬＡ基因５＇调控区序列。ＥｃｏＲ     

Antioxidant survey to assess antagonism to redox stress using a prokaryotic and an eukaryotic system

Using a prokaryote (Escherichia coli) and a metazoa-resembling eukaryote (Ochromonas danica), we surveyed antioxidants which might overcome redox stress imposed by menadione sodium bisulphite (MD) and buthionine sulphoximine (BSO). BSO oxidant stress was evident only inO. danica; MD oxidant stress was evident in both organisms. Glutathione, its precursors, e.g. cysteine, homocysteine, and 2-oxo-4-thiazolidine carboxylic acid, and red blood cells, emerged as prime antioxidants for relieving BSO and MD oxidant stress. BSO and MD oxidant activity and antioxidant-annulling effect inO. danica were judged comparable to those found in animal cells whereas the resultsE. coli were not entirely equivalent. TheO. danica system emerged as a practical, rapid, and useful system for pinpointing oxidant stressors and antioxidants, and shows promise for studies with mammalian systems.     

Butterflies and ants: The communicative domain

Associations with ants, termed myrmecophily, are widespread in the butterfly family Lycaenidae and range from mere co-existence to more or less specific mutualistic or even parasitic interactions. Secretions of specialized epidermal glands are crucial for mediating the interactions. Transfer of nutrients (carbohydrates, amino acids) from butterfly larvae to ants plays a major role, but manipulative communication with the help of odour signals is also involved. By means of myrmecophily, lycaenid butterflies largely escape ant predation, and certain species gain protection through attendant ants or achieve developmental benefits from ant-attendance. Benefits to the ants range from minimal to substantial food rewards. While most lycaenid species maintain facultative relationships with a variety of ant genera, highly specific and obligatory associations have convergently evolved in a number of butterfly lineages. As a corollary, communication systems are largely unspecific in the former, but may be highly specialized in the latter. The sophisticated communication between obligate myrmecophiles and their host ants is tightly connected with the evolutionary rise of specialized life-cycles and thus is a source of augmenting diversity within the butterflies.     

Affinity Solvents for Intensified Organics Extraction： Development Challenges and Prospects

Introduction In contrast to inorganics and metals processing, most organics extraction processes use classical organic sol-vents that utilize physical interactions with the solutes of interest to achieve the desired separation[1]. Clear examples are the e…     

中国美学在21世纪的世界性意义

上个世纪的亚洲美学家们往往依据西方美学传统的基本模式来考察各种美学问题；但实际上，亚洲各国也有自己的与西方不同的美学传统。通过对中西美学传统的比较性考察，探讨中国美学在21世纪人类美学的总体发展中所具有的世界性意义。从中国美学的视点看，美不仅在人与审美对象的关系中具有单纯审美的意义，而且更在人的存在自身中具有形而上的意义；人不仅是审美对象和艺术作品的创造者，而且首先是人自身美的存在的创造者。事实上，只有当人自身的存在首先在形而上的意义上达到了美的层面时，人才有可能一方面在外部世界中创造出审美的对象，另一方面在内心世界中形成审美的心理。中国美学的这一洞见无疑能够大大扩展21世纪人类美学的理论视界和研究内容，使其超出西方美学传统的有限观念，甚至将其提升到人的存在的形而上层面，从而使其对人类的进步发展做出更大的贡献。