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951.
Background and aim
Hyperin, a flavonol compound extracted from the Chinese herb Abelmoschus manihot L. Medic, is reported to exert protective actions in cerebral ischemic injury. The specific aim of the present study was to study the relaxation of Hyperin in rat isolated basilar artery and identify the underlying cellular mechanisms.Methods
Rat isolated basilar artery segments were cannulated and perfused while being superfused with PSS solution. Vessel images were recorded by video microscopy and diameters measured. Membrane potential was recorded using glass microelectrodes to evaluate the basilar artery smooth muscle cell hyperpolarization.Results
Perfusion of Hyperin (1 ~ 100 μM) elicited a concentration-dependent relaxation of basilar artery segments preconstricted with 0.1 μM U46619. The response was significantly inhibited by the removal of the endothelium. Hyperin also elicited marked and concentration-dependent hyperpolarization of smooth muscle cells. 30 μM nitro-L-arginine (an inhibitor of nitric oxide synthase) and indomethacin (an inhibitor of cyclooxygenase), partially inhibited Hyperin-induced relaxation and hyperpolarization leaving an attenuated, but significant, endothelium-dependent relaxation and hyperpolarization. This remaining effect was almost completely blocked by 1 mM tetraethylammonium (an inhibitor of Ca2+-activated K+ channels), or by 100 μM DL-propargylglycine, an inhibitor of cystathionine-γ-lyase (a synthase of the endogenous H2S).Conclusion
These findings show that Hyperin produces significant hyperpolarization in rat basilar artery smooth muscle cells and relaxation through both endothelium-dependent and endothelium-independent mechanisms. The underlying mechanisms appeared to be multi-factorial involving nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor (EDHF). Our data further suggest that endogenous H2S is a component of the EDHF-mediated hyperpolarization and relaxation to Hyperin. 相似文献952.
"强柱弱梁"是确保大震不倒的一项重要设计原则,是框架结构的基本抗震手段和重要措施,是一种理想的抗震屈服体制,但真正实现起来却有一定难度。 相似文献
953.
Zhao KJ Dong TT Tu PF Song ZH Lo CK Tsim KW 《Journal of agricultural and food chemistry》2003,51(9):2576-2583
The roots of Angelica sinensis (Danggui), a traditional Chinese medicine, have been used for invigorating blood circulation for over 2000 years in China. Three common species of Angelica roots are found in Asia: A. sinensis from China, A. acutiloba from Japan, and A. gigas from Korea. By using a molecular genetic approach, the 5S-rRNA spacer domains of the three species of Angelica were amplified, and their nucleotide sequences were determined. Diversity in DNA sequences among various species was found in their 5S-rRNA spacer domains, which could serve as markers for authentic identification of Angelica roots. In chemical analyses, the main constituents of Angelica roots including ferulic acid and Z-ligustilide were determined by HPLC; roots of A. sinensis were clearly distinct in that they contained approximately 10-fold higher levels of ferulic acid and Z-ligustilide as compared to roots of A. acutiloba and A. gigas. In addition, the amounts of main constituents in roots of A. sinensis varied according to different regions of cultivation and different methods of preservation. The chemical profile determined by HPLC therefore could serve as a fingerprint for quality control of Angelica roots. 相似文献
954.
955.
为了探讨添加冷冻干燥保护剂对Lactobacillus.plantarum(L.plantarum)LIP-1微胶囊性能的影响,该试验以植物乳杆菌(L.plantarum) LIP-1微胶囊的包埋率和冻干存活率为指标,通过单因素及正交试验,筛选出最佳冷冻干燥保护剂,在此基础上将其添加到微胶囊中,观察对L.plantarum LIP-1微胶囊形态、释放性等性能的影响。试验结果表明冷冻干燥保护剂的最佳配方为质量分数分别为甘油2%、麦芽糖1%、L-半胱氨酸2%、乳糖2%,此时微胶囊的包埋率为67.60%,冻干存活率为83.80%;与未添加保护剂的空白对照组相比,添加适宜保护剂的微胶囊在表观形态、肠液释放性、耐胃酸性及在不同温度(4、20、37℃)下的耐贮藏性能均显著提高(P<0.05)。添加适宜保护剂的微胶囊表面更加光滑致密,粒径更小,约100 μm(空白对照组约为150~200 μm);在模拟肠液中,添加适宜保护剂的微胶囊完全释放仅需60 min,而空白对照组需要90 min才能释放完全;在耐胃酸性上,添加适宜保护剂的LIP-1微胶囊在120min后,活菌数才开始显著下降(P<0.05),150 min后,活菌数下降约30%;空白对照组在90 min后活菌数开始显著下降(P<0.05),150 min后,活菌数下降约44%;在4、20、37℃贮藏28 d后,加保护剂组的活菌数分别下降0.76、1.33、1.88 lg(cfu/g),而空白对照组的活菌数分别下降0.96、 1.50、2.40 lg(cfu/g)。试验结果表明添加适宜的冷冻干燥保护剂可以提高L.plantarum LIP-1微胶囊的性能,为工业化生产中提高益生菌微胶囊的性能提供一定的理论和技术指导。 相似文献
956.
957.
Oryza granulata, an upland wild rice species, represents an unique germplasm for possessing abilities of tolerance to shade and drought,
immune to bacterial blight and resistance to brown planthopper. Although low degree of genetic variability has been revealed
within its populations, little genetic information at the species level is available in determining rational conservation
strategies. Here we used dominant DNA marker random amplified polymorphism DNA (RAPD) to assess the genetic variability among
23 accessions of O. granulata that collected from main distribution areas worldwide. Twenty decamer primers generated a total of 243 bands, with 83.5%
of them (203 bands) being polymorphic. Calculation of Shannon index of diversity revealed an average value of 0.42 ± 0.25,
indicating that O. granulata maintains a relatively high degree of genetic diversity on the species level. Analysis of genetic dissimilarity (GD) showed
that genetic differentiation occurred among studied accessions, which supports the feasibility of current ex situ conservation strategies. We also suggested that information based on population studies, which could be achieved by international
co-operation, is needed to conserve this widespread germplasm more effectively. 相似文献
958.
Ji-Hoon Kim Won Sik Shin Dong-Ik Song Sang June Choi 《Water, air, and soil pollution》2005,166(1-4):367-380
Single- and bi-solute sorption and desorption of 2,4-dichlorophenol (2,4-DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) in montmorillonite modified with hexadecyltrimethylammonium (HDTMA) were investigated using multi-step sorption and desorption procedure. Effect of pH on the multi-step sorption and desorption was investigated. As expected by the magnitude of octanol-water partition coefficient, K ow , both sorption and desorption affinity of 2,4,5-TCP was higher than that of 2,4-DCP at pH 4.85 and 9.15. For both chlorophenols, the protonated speciation (at pH 4.85) exhibited a higher affinity in both sorption and desorption than the predominant deprotonated speciation (about 95% and 99% of 2,4-dichlorophenolate and 2,4,5-trichlophenolate anions at pH 9.15, respectively). Desorption of chlorinated phenols was strongly dependent on the current pH regardless of their speciation in the previous sorption stage. Freundlich model was used to analyze the single-solute sorption and desorption data. No appreciable desorption-resistant (or non-desorbing) fraction was observed in organoclays after several multi-step desorptions. This indicates that sorption of phenols in organoclay mainly occurs via partitioning into the core of the pseudo-organic medium, thereby causing desorption nearly reversible. In bisolute competitive systems, sorption (or desorption) affinity of both chlorophenols was reduced compared to that in its single-solute system due to the competition between the solutes. The ideal adsorbed solution theory (IAST) coupled to the single-solute Freundlich model successfully predicted bisolute multi-step competitive sorption and desorption equilibria. 相似文献
959.
960.
Y. N. Song P. Marschner L. Li X. G. Bao J. H. Sun F. S. Zhang 《Biology and Fertility of Soils》2007,44(2):307-314
Cereal/cereal and cereal/legume intercropping systems are popular in the north, northwest, and southwest of China and often
result in yield increases compared to monocropping. Rhizosphere interactions may play a significant role in the yield increases,
particularly with respect to nutrient availability. The aim of this study was to investigate the effects of intercropping
on N availability and community composition of ammonia-oxidizing bacteria in the rhizosphere of wheat, maize, and faba bean
at different growth stages. Denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA genes was used to analyze the
community composition of bacterial ammonia oxidizers belonging to β-proteobacteria. The results showed that intercropping
with faba bean significantly increased nitrate concentrations in the rhizosphere of wheat and maize at the second sampling
time (20 June) compared to monocropping or intercropping between maize and wheat. Intercropping significantly affected the
community composition of ammonia-oxidizing bacteria in the rhizosphere compared to monocropping, and the effects were most
pronounced in the maize/faba bean and wheat/maize intercropping systems when faba bean and wheat were at anthesis and maize
was in seedling stage. In wheat/faba bean intercropping, the effects of intercropping on community composition of ammonia-oxidizing
bacteria were less pronounced at the seedling stage of the two species but were significant at anthesis. 相似文献