RGDS肽对大鼠主动脉球囊内膜剥脱后血管壁增殖的影响

在大鼠主动脉球囊内膜剥脱术后血管壁细胞过度增殖模型上,用合成的血小板膜纤维蛋白原受体（ｇｌｙｃｏｐｒｏｔｅｉｎⅡｂ／Ⅲａｃｏｍｐｌｅｘ,ＧＰⅡｂ／Ⅲａ）拮抗剂ＲＧＤＳ（Ａｒｇ－Ｇｌｙ－Ａｓｐ－Ｓｅｒ,５０μｍｏｌ·ｋｇ－１·ｄ－１）治疗可有效地抑制损伤血管壁的细胞计数增加和内膜增厚以及血管平滑肌细胞增殖,显著降低其血管组织３Ｈ－ＴｄＲ和３Ｈ－Ｌｅｕ的参入增加程度。实验结果提示ＲＧＤＳ肽作为血管成型术的辅佐剂,对于防治血管再狭窄可能具有潜在的临床应用前景。     

蜂毒素与紫膜的相互作用机理研究──与三种表面活性剂的比较

用吸收光谱和圆二色谱的方法研究了蜂毒素与嗜血菌紫膜的相互作用机理．通过与三种在结构和电荷上不同的表面活性剂与紫膜的作用相比较,可以年出蜂毒作为带正电荷的分子与同样带正电的表面活性剂ＤＴＡＢ在引起紫膜凝聚方面表现相同;但在对紫膜可见光区的吸收光谱和圆二色谱的影响上却与具有刚性结构的ＣＨＡＰＳ相似,表明蜂毒可在紫膜表面以一种刚性较大的构象（如α螺旋）存在,不能进入膜蛋白流水区的深层．另外,从紫膜－Ｔｒｉｔｏｎ－蜂毒混合作用体系的研究中得到如下推测：蜂毒与Ｔｒｉｔｏｎ竞争菌紫质分子周围的结合位点,可排斥位于菌紫质周围的Ｔｒｉｔｏｎ分子．表明蜂毒具有比Ｔｒｉｔｏｎ更强的与菌紫质的亲和力,从而提供了支持蜂毒分子存在与膜蛋白－菌紫质的直接相互作用的有力证据．     

内皮素对失血性休克鼠脑微循环的影响及尼莫地平、川芎嗪的治疗作用

利用大鼠颅骨开窗观察软脑膜微循环的方法研究了内皮素（ＥＴ－１）１０－１０－１０－７ｍｏｌ／Ｌ对软脑膜微循环的影响以及失血性休克时软脑膜对ＥＴ－１的反应性。并用１０－７ｍｏｌ／Ｌ造成失血性休克后脑血管痉挛的模型,观察尼莫地平、川芎嗪、６５４－２对内皮素引起血管痉挛的治疗作用。１０－９、１０－８和１０－７ｍｏｌ／Ｌ３种浓度ＥＴ－１可使软脑膜小动脉、细动脉强烈收缩,收缩率分别为２７．７％、４６．８％、７８．５％,其收缩强度与ＥＴ－１的浓度有关。对静脉的作用不明显。１０－１０ｍｏｌ／ＬＥＴ－１可使细动脉轻度扩张。出血性休克时,软脑膜血流明显减慢,小动脉、细动脉管径对ＥＴ－１的收缩作用更敏感,脑组织血流明显减少。尼莫地平具有较好的拮抗ＥＴ－１引起软脑膜动脉的收缩和改善局部微循环的作用。川芎嗪也能拮抗ＥＴ－１引起软脑膜动脉的收缩,但作用较尼莫地平弱。６５４－２不能缓解ＥＴ－１对软脑膜动脉的收缩作用。     

促进兴安落叶松天然更新的出苗条件研究

根据４０多块标准地调查,促进更新措施后兴安落叶松１年生幼苗出现的频度及数量与种子年关系很大,幼苗更新效果最好的是种子年当年,更新频度可达６０％以上,幼苗平均为１．０—２．０×１０３株·ｈａ－１,其他年份促进的效果较差．同时,也与迹地类型、种源状况和整地质量关系较大．一般在山坡中、下部,土壤湿润的杜香落叶松和藓类越桔落叶松林迹地促进效果较好,其更新频度为６０—７０％．绝大部分更新幼苗出现在表土裸露、无杂草灌木、土壤湿润的地方．更新频度与植被盖度呈明显的衰减指数相关．促进地块距下种林墙最好不超过６０ｍ范围．     

印度木薯花叶病毒DNA在寄主植物中可能存在的形式

从印度木薯花叶病毒（ＩＣＭＶ）侵染的植物中纯化特异的核酸,经ＲＮＡａｓｅ,ＤＮＡａｓｃ,Ｎｕｃｌｅ－ａｓｅＳｌ,ＥｘｏｎｕｃｌｅａｓｅⅢ和ＥｃｏＲＩ酶切,Ｓｏｕｔｈｅｒｎ和Ｄｏｔｂｌｏｔｓ杂交证实,在感病的植株中,存在两种形式的病毒核酸：环状双链ＤＮＡ和环状单链ＤＮＡ,后者可能是病毒ＤＮＡ的（－）链,环状双链ＤＮＡ经限制性内切酶作用可得２．７ｋｂ的线性双链ＤＮＡ纯化的病毒核酸含ＤＮＡ１和ＤＮＡ２两个分子量相近的组份。     

Polyamine regulation of Na+/glucose symporter expression in LLC-PK1 cells

Addition of polyamines or their analogs to newly confluent LLC-PK₁ cells resulted in down-regulation of Na⁺-glucose transport (symport) activity. Polyamines prevented the induction of this symporter by the differentiation inducer hexamethylene bisacetamide (HMBA) but did not influence induction by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Partial depletion of endogenous polyamines after addition of α -difluoromethylornithine (DFMO) resulted in a 4 to 5-fold increase in symporter expression. Symporter induction by either HMBA or DFMO was inhibited by the protein kinase inhibitor H-7 but H-7 did not affect symporter induction by IBMX. Changes in symporter activity were accompanied by changes in levels of the 75 kD symporter subunit detected by Western blot. Cultures exposed to HMBA exhibited reduced levels of ornithine decarboxylase activity. Our results suggest that induction of symporter expression by HMBA may be mediated in part by its effects on polymine metabolism, and point to parallel roles of polyamines and cyclic AMP in regulating the expression of this physiologically important renal transport system. © 1993 Wiley-Liss, Inc.     

Genomic concatemerization/deletion in rotaviruses: a new mechanism for generating rapid genetic change of potential epidemiological importance.

Three variants of group A rotavirus with large changes in their gene 5 structures have been analyzed at the molecular level. The first of these, P9 delta 5, was obtained during plaque purification undertaken as part of the biological cloning of a field isolate of virus. The gene 5 homolog in this isolate migrated just ahead of the normal segment 6 RNA, giving an estimated size of 1,300 bp. Molecular cloning and sequencing of this homolog revealed it to have a single 308-bp deletion in the center of the normal gene 5 sequence extending between nucleotides 460 and 768 of the normal gene sequence. This deletion caused a frameshift in the gene such that a stop codon was encountered 8 amino acids downstream of the deletion point, giving a predicted size for the protein product of this gene of 150 amino acids compared with the 490 amino acids of its normal-size counterpart. Attempts to detect this shortened protein in virus-infected cells were not successful, indicating that it was much less stable than the full-length protein and/or had suffered a large change in its antigenicity. The second two variants, brvA and brvE, were generated in an earlier study following the high-multiplicity passage of the UKtc strain of bovine rotavirus. Polyacrylamide gel electrophoresis analysis of these nondefective variants showed that brvA had a gene 5 homolog approximately equal in size to the normal RNA segment 2 (approximately 2,700 bp) and that brvE had a size of approximately 2,300 bp. Both variants showed changes in their gene 5 protein products, with brvA mimicking P9 delta 5 in failing to produce a detectable product whereas brvE produced a new virus-specific protein approximately 80 kDa in size. Full-length cDNA clones of the brvE gene 5 homolog were isolated, and analysis of their structure revealed a head-to-tail concatemerization of the normal gene 5 sequence with the first copy of the concatemer covering nucleotides 1 to 808 and the second covering nucleotides 92 to 1579, giving a total length of 2,296 bp. Sequencing across the junction region of the two copies of the gene showed that they were joined in frame to give a predicted combined open reading frame of 728 amino acids with the amino-terminal region consisting of amino acids 1 to 258 fused at the carboxy terminus to amino acids 21 to 490.(ABSTRACT TRUNCATED AT 400 WORDS)     

低剂量CO2激光对茄子,青椒叶绿体超微结构影响的初步观察

本试验用功率密度为825mw/cm~2的CO_2激光照射茄子干种子(含水量8.33％)13s、青椒干种子(含水量5.4％)3s,分别以Os为对照(ck)。照射后播于生长箱内,出苗10天分苗于玻璃温室内,于四叶期取样观察成熟叶片叶绿体的超微结构。发现激光照射处理的茄子、青椒的叶绿体的基质片层、基粒片层有明显的吸胀现象。     

用HPLC证实单糖在酸性处理中的变化

<正> 在碱性条件下,醛糖与酮糖之间会发生结构互变。然而美国学者Feather M S等经过十多年的研究,发现在酸性条件下,葡萄糖、甘露糖和果糖之间也有分子内的互变,并应用~3H放射标记等技术,提出了互变的反应机理,这一互变的存在给寡糖及多糖的组份分析带来了一个问题,即用酸性条件水解寡糖或多糖后,如何确定其中的葡萄糖、甘露糖或果糖     

Three research priorities for just and sustainable urban systems: Now is the time to refocus

Now is the time to refocus efforts in urban research and design. A changing climate and extreme weather events are presenting unique challenges to urban systems around the world. These challenges illuminate the social barriers that accompany disruptive events such as resource inequities and injustices. In this perspective, we provide three research priorities for just and sustainable urban systems that help to address these matters. The three research priorities are: (1) social equity and justice, (2) circularity, and (3) digital twins. Conceptual context and future research directions are provided for each. For social equity and justice, the future directions are mandatory equity analysis and inclusionary practices, understanding and reconciling historical injustices, and intentional integration with diverse community stakeholders. For circularity applications, they are better metrics for integration, more robust evaluation frameworks, and dynamic modeling at multiple spatial and temporal scales. Future directions for digital twins include developing principles to reduce complexity, integrating model and system components, and reducing barriers to data access. These research priorities are core to meeting several of the United Nations Sustainable Development Goals (i.e., 1—No Poverty, 8—Decent Work and Economic Growth, 10—Reduced Inequalities, and 11—Sustainable Cities and Communities). Useful social and technical matters are discussed throughout, where we highlight the importance of prioritizing localized research efforts, provide guidance for community-engaged research and co-development practices, and explain how these priorities interact to align with the evolving field of industrial ecology.