排序方式: 共有268条查询结果,搜索用时 15 毫秒
101.
Tattum MH Cohen-Krausz S Thumanu K Wharton CW Khalili-Shirazi A Jackson GS Orlova EV Collinge J Clarke AR Saibil HR 《Journal of molecular biology》2006,357(3):975-985
In prion diseases, the mammalian prion protein PrP is converted from a monomeric, mainly alpha-helical state into beta-rich amyloid fibrils. To examine the structure of the misfolded state, amyloid fibrils were grown from a beta form of recombinant mouse PrP (residues 91-231). The beta-PrP precursors assembled slowly into amyloid fibrils with an overall helical twist. The fibrils exhibit immunological reactivity similar to that of ex vivo PrP Sc. Using electron microscopy and image processing, we obtained three-dimensional density maps of two forms of PrP fibrils with slightly different twists. They reveal two intertwined protofilaments with a subunit repeat of approximately 60 A. The repeating unit along each protofilament can be accounted for by elongated oligomers of PrP, suggesting a hierarchical assembly mechanism for the fibrils. The structure reveals flexible crossbridges between the two protofilaments, and subunit contacts along the protofilaments that are likely to reflect specific features of the PrP sequence, in addition to the generic, cross-beta amyloid fold. 相似文献
102.
Zeinab Sahraei Beiranvand Amir Reza Abbasi Sara Dehdashtian Ziba Karimi Azadeh Azadbakht 《Analytical biochemistry》2017
Herein, an ultrasensitive electrochemical aptasensor for quantitative detection of bisphenol A (BPA) was fabricated based on a novel signal amplification strategy. This aptasensor was developed by electrodeposition of gold-platinum nanoparticles (Au-PtNPs) on glassy carbon (GC) electrode modified with acid-oxidized carbon nanotubes (CNTs-COOH). In this protocol, acriflavine (ACF) was covalently immobilized at the surface of glassy carbon electrode modified with Au-PtNPs/CNTs-COOH nanocomposite. Attachment of BPA-aptamer at the surface of modified electrode was performed through the formation of phosphoramidate bonds between the amino group of ACF and phosphate group of the aptamer at 5′end. By interaction of BPA with the aptamer, the conformational of aptamer was changed which lead to retarding the interfacial electron transfer of ACF as a probe. Sensitive quantitative detection of BPA was carried out by monitoring the decrease of differential pulse voltammetric (DPV) responses of ACF peak current with increasing the BPA concentration. The resultant aptasensor exhibited good specificity, stability and reproducibility, indicating that the present strategy was promising for broad potential application. 相似文献
103.
Azadeh Askarinejad 《Inorganica chimica acta》2006,359(10):3379-3383
A three-dimensional polymeric KITlI heterometallic compound [K2Tl(μ-C4H4O4)(μ-NO3)]n, with mixes succinate and nitrate ligands, has been synthesized and characterized. Its single-crystal X-ray structure shows two types of K+-ions with coordination numbers of seven and eight and one Tl+-ion with a coordination number of five. However, the arrangement of O-atoms for TlI suggests a gap or hole in the coordination geometry around this atom. This ‘hole’ is possibly occupied by a stereochemically ‘active’ electron lone pair of thallium atoms. Two hydrogen atoms of succinate situated 3.26 Å above the proposed site on the lone pair of TlI is oriented in such a way that it might be thought to be forming weak Tl-Lp?H-C hydrogen bond or agostic interactions, thus attaining of environment TlO5H2. 相似文献
104.
Ali El-Armouche Azadeh Wahab Katrin Wittköpper Thomas Schulze Lutz Pohlmann Jenna F. DuMond Rainer H. Böger Thomas Eschenhagen Lucie Carrier Sonia Donzelli 《Biochemical and biophysical research communications》2010,402(2):340-1698
Contractile dysfunction and diminished response to β-adrenergic agonists are characteristics for failing hearts. Chemically donated nitroxyl (HNO) improves contractility in failing hearts and thus may have therapeutic potential. Yet, there is a need for pharmacologically suitable donors. In this study we tested whether the pure and long acting HNO donor, 1-nitrosocyclohexyl acetate (NCA), affects contractile force in normal and pathological ventricular myocytes (VMs) as well as in isolated hearts. VMs were isolated from mice either subjected to isoprenaline-infusion (ISO; 30 μg/g per day) or to vehicle (0.9% NaCl) for 5 days. Sarcomere shortening and Ca2+ transients were simultaneously measured using the IonOptix system. Force of contraction of isolated hearts was measured by a Langendorff-perfusion system. NCA increased peak sarcomere shortening by + 40-200% in a concentration-dependent manner (EC50 ∼55 μM). Efficacy and potency did not differ between normal and chronic ISO VMs, despite the fact that the latter displayed a markedly diminished inotropic response to acute β-adrenergic stimulation with ISO (1 μM). NCA (60 μM) increased peak sarcomere shortening and Ca2+ transient amplitude by ∼200% and ∼120%, respectively, suggesting effects on both myofilament Ca2+ sensitivity and sarcoplasmic reticulum (SR) Ca2+ cycling. Importantly, NCA did not affect diastolic Ca2+ or SR Ca2+ content, as assessed by rapid caffeine application. NCA (45 μM) increased force of contraction by 30% in isolated hearts. In conclusion, NCA increased contractile force in normal and β-adrenergically desensitized VMs as well as in isolated mouse hearts. This profile warrants further investigations of this HNO donor in the context of heart failure. 相似文献
105.
Sangouni Abbas Ali Ahmadi Vasmehjani Azam Mohammadi Mohammad Nadjarzadeh Azadeh Ferns Gordon A. Mirzaei Masoud Khayyatzadeh Sayyed Saeid 《Sleep and biological rhythms》2022,20(3):327-335
Sleep and Biological Rhythms - Sleep disorders are linked to obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). The evidence suggests that dietary carbohydrate content may... 相似文献
106.
In addition to its role as the primary vector for dengue viruses, Aedes aegypti has a long history as a genetic model organism for other bloodfeeding mosquitoes, due to its ease of colonization, maintenance and reproductive productivity. Though its genome has been sequenced, functional characterization of many Ae. aegypti genes, pathways and behaviors has been slow. TALE nucleases (TALENs) have been used with great success in a number of organisms to generate site-specific DNA lesions. We evaluated the ability of a TALEN pair to target the Ae. aegypti kmo gene, whose protein product is essential in the production of eye pigmentation. Following injection into pre-blastoderm embryos, 20–40% of fertile survivors produced kmo alleles that failed to complement an existing khw mutation. Most of these individuals produced more than 20% white-eyed progeny, with some producing up to 75%. Mutant alleles were associated with lesions of 1–7 bp specifically at the selected target site. White-eyed individuals could also be recovered following a blind intercross of G1 progeny, yielding several new white-eyed strains in the genetic background of the sequenced Liverpool strain. We conclude that TALENs are highly active in the Ae. aegypti germline, and have the potential to transform how reverse genetic experiments are performed in this important disease vector. 相似文献
107.
Lipid-assisted microinjection: introducing material into the cytosol and membranes of small cells. 总被引:3,自引:0,他引:3 下载免费PDF全文
The microinjection of synthetic molecules, proteins, and nucleic acids into the cytosol of living cells is a powerful technique in cell biology. However, the insertion of a glass micropipette into the cell is a potentially damaging event, which presents significant problems, especially for small mammalian cells (spherical diameter = 2-15 micron), especially if they are only loosely adherent. The current technique is therefore limited to cells that are both sufficiently large or robust and firmly attached to a substrate. We describe here a modification of the standard technique that overcomes some of the problems associated with conventional microinjection but that does not involve the insertion of a micropipette deep into the cell cytoplasm. Instead, this method depends on lipid fusion at the micropipette tip to form a continuous but temporary conductance pathway between the interiors of the micropipette and cell. This technique thus also provides a novel method of transferring lipids and lipid-associated molecules to the plasma membrane of cells. 相似文献
108.
Jia H Bagherzadeh A Bicknell R Duchen MR Liu D Zachary I 《The Journal of biological chemistry》2004,279(34):36148-36157
Vascular endothelial growth factor (VEGF)-D binds to VEGF receptors (VEGFR) VEGFR2/KDR and VEGFR3/Flt4, but the signaling mechanisms mediating its biological activities in endothelial cells are poorly understood. Here we investigated the mechanism of action of VEGF-D, and we compared the signaling pathways and biological responses induced by VEGF-D and VEGF-A in endothelial cells. VEGF-D induced KDR and phospholipase C-gamma tyrosine phosphorylation more slowly and less effectively than VEGF-A at early times but had a more sustained effect and was as effective as VEGF-A after 60 min. VEGF-D activated extracellular signal-regulated protein kinases 1 and 2 with similar efficacy but slower kinetics compared with VEGF-A, and this effect was blocked by inhibitors of protein kinase C and mitogen-activated protein kinase kinase. In contrast to VEGF-A, VEGF-D weakly stimulated prostacyclin production and gene expression, had little effect on cell proliferation, and stimulated a smaller and more transient increase in intracellular [Ca(2+)]. VEGF-D induced strong but more transient phosphatidylinositol 3-kinase (PI3K)-mediated Akt activation and increased PI3K-dependent endothelial nitric-oxide synthase phosphorylation and cell survival more weakly. VEGF-D stimulated chemotaxis via a PI3K/Akt- and endothelial nitric-oxide synthase-dependent pathway, enhanced protein kinase C- and PI3K-dependent endothelial tubulogenesis, and stimulated angiogenesis in a mouse sponge implant model less effectively than VEGF-A. VEGF-D-induced signaling and biological effects were blocked by the KDR inhibitor SU5614. The finding that differential KDR activation by VEGF-A and VEGF-D has distinct consequences for endothelial signaling and function has important implications for understanding how multiple ligands for the same VEGF receptors can generate ligand-specific biological responses. 相似文献
109.
Zeinoddini Mehdi Azizi Azadeh Bayat Shiva Tavasoli Zeinab 《Plasmonics (Norwell, Mass.)》2018,13(2):583-590
Plasmonics - Detection of diphtheria toxin (DT) which is produced by Corynebacterium diphtheria, a zoonotic pathogen and a leading cause of diphtheria, is the critical step in the clinical... 相似文献
110.
Jalali Seyyed Mostafa Morteza Abdollahi Atiyeh Hosseini Dehghani Kari Bozorg Ajami Marjan Azadeh Kimia Moiniafshar 《生物学前沿》2018,13(6):475-480