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1.
Evidence for direct arrhythmogenic action of endothelin. 总被引:8,自引:0,他引:8
R Yorikane H Shiga S Miyake H Koike 《Biochemical and biophysical research communications》1990,173(1):457-462
We studied electrophysiological effects of endothelin on canine cardiac tissues. Endothelin prolonged action potential duration and decreased spontaneous firing rate of the right bundle branch cells. At a concentration of 2 x 10(-7)M the plateau phase of action potentials was flattened, followed by the abrupt occurrence of early afterdepolarizations (EADs). ET, at a concentration as low as 2 x 10(-9)M, was capable of inducing EADs although their incidence was low. The EADs were initiated from the membrane potential less negative than -30mV and were suppressed by nicardipine, suggesting the involvement of dihydropyridine-sensitive Ca2+ channels in the induction of EADs. Because EADs are considered to underlie certain types of arrhythmias endothelin per se may have arrhythmogenic action. 相似文献
2.
Specific receptors for endothelin on membranes from human placenta. Characterization and use in a binding assay 总被引:3,自引:0,他引:3
High-affinity binding sites for endothelin have been found in a human placenta membrane preparation. 125I-endothelin bound to placenta membranes at 20 degrees C with an association half-time of 30 min, whereas the binding was only slowly reversed with a dissociation half-time of 250 min. In saturation experiments, a single class of high-affinity binding sites was identified with an apparent dissociation constant (KD) of 24 pM and a maximal density of 240 fmol per mg of protein. The binding of 125I-endothelin was half-maximally inhibited by cold endothelin at a concentration (IC50) of 140 pM. In contrast, no inhibition was found at 10(-4) M for a variety of vasoactive peptides such as angiotensin II, vasopressin, neuropeptide Y, substance P, CGRP, bradykinin, leucine enkephalin or dynorphin A. Similarly, the binding was modulated neither by the calcium channel blockers nifedipine, verapamil or diltiazem, nor by the calcium channel agonist Bay k 8644. There was also no effect with the structurally-related bee venom apamin. Using this membrane preparation, endothelin-like activity could be measured in the medium of cultured human endothelial cells by competition binding technique. 相似文献
3.
Two new sesquiterpenoids (1 and 2) and a new ent-pimarane type diterpenoid (3), together with eighteen known compounds (4–21), were isolated from the whole plants of Siegesbeckia pubescens. The structures of the new compounds were determined on the basis of 1D-, 2D NMR and HRESIMS data. All compounds were evaluated for their inhibitory effects on LPS-induced nitric oxide production in RAW 264.7 macrophages. Of these, highly oxygenated germacrane type sesquiterpenoids (1–2 and 13–14) showed significant inhibitory effects with IC50 values ranging from 3.9 to 16.8 μM. 相似文献
4.
建立一种靶点蛋白质快速定量检测方法。在原有侧向流动免疫层析技术的基础上,通过优化层析材料和纳米微球的均一性、改进检测区的检测方法,经逐点扫描技术,建立标准浓度曲线,以达到对临床靶点蛋白质的定量检测。以乳腺癌组织中的Her2表达为例,通过对已知浓度样品的检测,验证本技术方法的准确度大于96%。另外,以蛋白质免疫印迹作为组织中特定蛋白质检测金标准,分析临床肿瘤组织中Her2蛋白的含量,其准确率也达到95.5%,而免疫组织化学方法检测准确率仅为69.58%。新型免疫层析法检测结果与靶向治疗患者的愈后密切相关(P<0.01)。改进后的新型免疫层析方法能够准确地对临床靶点蛋白质进行定量检测,而且结合侧向流动技术的简单、快速和易用性,这种新型检测方法可以广泛应用于临床组织标本、血液标本和体液标本中靶点蛋白质的临场定量检测,在一定程度上可以替代免疫组化技术。 相似文献
5.
《Harmful algae》2015
A differential screening study using high-resolution (HR)-hydrophilic interaction chromatography (HILIC)-electrospray ionization (ESI)–quadrupole time-of-flight mass spectrometry (Q-TOF MS) was conducted to identify saxitoxin (STX) analogues in the marine dinoflagellate toxic sub-clone Alexandrium tamarense Axat-2 and the non-toxic sub-clone UAT-014-009 derived from the same Japanese isolate. One unknown compound was identified only in the toxic sub-clone and was found to have the molecular formula C9H16N6O2. This structure differed from that of decarbamoyl STX (dcSTX; C9H16N6O3) by the loss of a single oxygen. A 12-deoxy-dcSTX standard (a mixture of 12α- and β-deoxy-dcSTX) was chemically prepared from dcSTX by reduction with sodium borohydride. The unknown compound in the toxic strain of A. tamarense was identified as 12β-deoxy-dcSTX by comparison of its HR-HILIC-LC–MS retention time and HR–MS/MS spectrum with those of the chemically prepared standard, and the identification was confirmed by high-sensitivity HPLC analysis with post-column fluorescent derivatization. Moreover, two Japanese isolates of A. catenella showing toxin profiles different from that of A. tamarense were also found to contain 12β-deoxy-dcSTX. Previously, 12β-deoxy-dcSTX was isolated from the freshwater cyanobacterium Lyngbya wollei, which produces a unique set of STX analogues. This study is the first evidence of the presence of 12β-deoxy-dcSTX in marine dinoflagellates. 相似文献
6.
Catherine Murphy Sarah Hotchkiss Jenny Worthington Stephanie R. McKeown 《Journal of applied phycology》2014,26(5):2211-2264
This review discusses studies on marine macroalgae that have been investigated for their potential as sources of novel anti-cancer drugs. The review highlights the very large number of studies of crude, partially purified and purified seaweed extracts, collected from many locations, which have shown potential as sources of potent anti-cancer drugs when tested in vitro and/or in vivo. The activity of polysaccharides, polyphenols, proteinaceous molecules, carotenoids, alkaloids, terpenes and others is described here. In some reports, mechanistic studies have identified specific inhibitory activity on a number of key cellular processes including apoptosis pathways, telomerase and tumour angiogenesis. However, despite the potential shown by these studies, translation to clinically useful preparations is almost non-existent. It is hoped this review will serve as a source document and guide for those carrying out research into the potential use of macroalgae as a source of novel anti-cancer agents. 相似文献
7.
The Saccharomyces cerevisiae MNN4 gene, which is involved inmannosylphosphate transfer from GDP-mannose to N-linked oligosaccharide,has been cloned from a lambda phage containing a yeast chromosomeXI DNA fragment The MNN4 ORF encodes a protein of 1178 aminoacids. The deduced amino acid sequence shows a topology of typeII membrane proteins and has a unique repeated sequence of lysineand glutamic acid at the C-terminus. Disruption and overexpressionof MNN4 led to a decrease and increase, respectively, of themannosylphosphate content in cell wall mannans prepared fromboth mnn4 and wild type strains. A dramatic decrease of mannosylphosphateoccurs in 相似文献
8.
Michael J. A. Simpson Donald F. Macintosh John B. Cloughley Angus E. Stuart 《Economic botany》1996,50(1):122-129
The development ofM. gale oil as an insect repellent has created a requirement for cultivation of the plant. Botanical evidence indicates thatM. gale is likely to thrive on well—aerated acid peatland and could become a valuable crop on land of low agricultural value. Plant growth would be enhanced by the prevention of grazing and could be combined with softwood forestry since the trees would benefit from soil nitrogen enrichment thanks to the symbiotic association ofM. gale andFrankia. The economics of oil production would be improved if additional compounds of value such as pharmacologically active fiavonoids could be extracted from the by-products. 相似文献
9.
Chie Amano Hideki Minematsu Kazuyo Fujita Shinki Iwashita Masaki Adachi Koichi Igarashi Shuji Hinuma 《PloS one》2015,10(9)
To explore a novel method using liposomes to suppress macrophages, we screened food constituents through cell culture assays. Curcumin was one of the strongest compounds exhibiting suppressive effects on macrophages. We subsequently tried various methods to prepare liposomal curcumin, and eventually succeeded in preparing liposomes with sufficient amounts of curcumin to suppress macrophages by incorporating a complex of curcumin and bovine serum albumin. The diameter of the resultant nanoparticles, the liposomes containing curcumin, ranged from 60 to 100 nm. Flow cytometric analyses revealed that after intraperitoneal administration of the liposomes containing curcumin into mice, these were incorporated mainly by macrophages positive for F4/80, CD36, and CD11b antigens. Peritoneal cells prepared from mice injected in vivo with the liposomes containing curcumin apparently decreased interleukin-6-producing activities. Major changes in body weight and survival rates in the mice were not observed after administrating the liposomes containing curcumin. These results indicate that the liposomes containing curcumin are safe and useful for the selective suppression of macrophages in vivo in mice. 相似文献
10.
Patrycja Konieczna Elisa Schiavi Mario Ziegler David Groeger Selena Healy Ray Grant Liam O’Mahony 《PloS one》2015,10(3)
The microbiota is required for optimal host development and ongoing immune homeostasis. Lactobacilli are common inhabitants of the mammalian large intestine and immunoregulatory effects have been described for certain, but not all, strains. The mechanisms underpinning these protective effects are beginning to be elucidated. One such protective organism is Lactobacillus rhamnosus JB-1 (Lb. rhamnosus JB-1). Lb. murinus has no such anti-inflammatory protective effects and was used as a comparator organism. Human monocyte-derived dendritic cells (MDDCs) were co-incubated with bacteria and analysed over time for bacterial adhesion and intracellular processing, costimulatory molecule expression, cytokine secretion and induction of lymphocyte polarization. Neutralising antibodies were utilized to identify the responsible MDDC receptors. Lb. rhamnosus JB-1 adhered to MDDCs, but internalization and intracellular processing was significantly delayed, compared to Lb. murinus which was rapidly internalized and processed. Lb. murinus induced CD80 and CD86 expression, accompanied by high levels of cytokine secretion, while Lb. rhamnosus JB-1 was a poor inducer of costimulatory molecule expression and cytokine secretion. Lb. rhamnosus JB-1 primed MDDCs induced Foxp3 expression in autologous lymphocytes, while Lb. murinus primed MDDCs induced Foxp3, T-bet and Ror-γt expression. DC-SIGN was required for Lb. rhamnosus JB-1 adhesion and influenced IL-12 secretion, while TLR-2 influenced IL-10 and IL-12 secretion. Here we demonstrate that the delayed kinetics of bacterial processing by MDDCs correlates with MDDC activation and stimulation of lymphocytes. Thus, inhibition or delay of intracellular processing may be a novel strategy by which certain commensals may avoid the induction of proinflammatory responses. 相似文献