Home About us Contact
|
Home About us Contact | ||
|
|
||
Pressure Application (pressure + application)
Selected AbstractsOnline CIEF-ESI-MS in glycerol,water media with a view to hydrophobic protein applicationsELECTROPHORESIS, Issue 23 2009Meriem Mokaddem Abstract A new online coupling of CIEF with ESI-MS has been developed in glycerol,water media. This improved protocol provides: (i) the electric continuity during the whole analysis by a discontinuous filling of the capillary with 60:40 (cm/cm) catholyte/proteins,ampholyte mixture; (ii) the use of an anticonvective medium, i.e. 30:70 glycerol/water, v/v, compatible with MS detection and as an aid to hydrophobic protein solubilization and (iii) the use of unmodified bare fused-silica capillaries, as the glycerol/water medium strongly reduces EOF. Focusing was performed in positive polarity and cathodic mobilization was achieved by both voltage and pressure application. The setup was optimized with respect to analysis time, sensitivity and precision on pI determination. The optimized anolyte and catholyte were composed of 50,mM formic acid/1,mM glutamic acid (pH 2.35) and 100,mM NH3/1,mM lysine (pH 10.6), respectively. The effects of ampholyte concentration, focusing time and ESI parameters were presented for model proteins and discussed. This new integrated protocol should be an easy and effective additional tool in the field of proteome analysis, providing a means for the characterization of a large number of hydrophilic and hydrophobic proteins. [source] Presynaptic muscarinic acetylcholine receptors suppress GABAergic synaptic transmission in the intermediate grey layer of mouse superior colliculusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2004Fengxia Li Abstract The intermediate grey layer (the stratum griseum intermediale; SGI) of the superior colliculus (SC) receives cholinergic inputs from the parabrachial region of the brainstem. It has been shown that cholinergic inputs activate nicotinic acetylcholine (nACh) receptors on projection neurons in the SGI. Therefore, it has been suggested that they facilitate the initiation of orienting behaviours. In this study, we investigated the effect of muscarinic acetylcholine (mACh) receptor activation on GABAergic synaptic transmission to SGI neurons using the whole-cell patch-clamp recording technique in slice preparations from mice. The GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) evoked in SGI neurons by focal electrical stimulation were suppressed by bath application of 10 µm muscarine chloride. During muscarine application, both the paired-pulse facilitation index and the coefficient of variation of IPSCs increased; however, the current responses induced by a transient pressure application of 1 mm GABA were not affected by muscarine. Muscarine reduced frequencies of miniature IPSCs (mIPSCs) while the amplitudes of mIPSCs remained unchanged. These results suggestd that mAChR-mediated inhibition of IPSCs was of presynaptic origin. The suppressant effect of muscarine was antagonized by an M1 receptor antagonist, pirenzepine dihydrochloride (1 µm), and a relatively specific M3 receptor antagonist, 4-DAMP methiodide (50 nm). By contrast, an M2 receptor antagonist, methoctramine tetrahydrochloride (10 µm), was ineffective. These results suggest that the cholinergic inputs suppress GABAergic synaptic transmission to the SGI neurons at the presynaptic site via activation of M1 and, possibly, M3 receptors. This may be an additional mechanism by which cholinergic inputs can facilitate tectofugal command generation. [source] High pressure studies of the radial breathing modes in double-wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007J. Arvanitidis Abstract This work focuses on the high pressure Raman study of the radial breathing modes (RBMs) of bundled double-wall carbon nanotubes (DWCNTs) using different excitation energies. The detailed examination of the Raman peaks attributed to the RBMs of the inner and outer tubes comprising the DWCNTs as a function of pressure provides a wealth of information concerning the pressure response of individual nanotubes as well as the inner-outer tube (intratube) interactions. The outer tube acts as a protection shield for the inner tube whereas the latter increase the structural stability of the externals upon pressure application. More importantly, the pressure response of the inner tubes, expressed by the normalized pressure slopes ,i = (1/,i) (,,i /,P) vs. frequency of their RBMs, shows a remarkable grouping in quasi-linear distributions wherein ,i increases with ,. This behavior is explained by assuming that the pressure response of an internal tube is crucially dependent on the intratube spacing and thus the structural characteristics of the encapsulating tube. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Endothelium-derived hyperpolarizing factor as an in vivo back-up mechanism in the cutaneous microcirculation in old miceTHE JOURNAL OF PHYSIOLOGY, Issue 2 2007Marie Line Gaubert There is now strong evidence that an endothelium-derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back-up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium-dependent relaxation, providing a novel situation in which to assess the contributions of EDHF. The purpose of the present study was thus to determine if, in vivo, there was a functional role for EDHF as a back-up mechanism in the cutaneous microcirculation in the ageing process. We investigated in vivo the contribution of each endothelial factor (NO, PG and EDHF) in the cutaneous vasodilatation induced by iontophoretic delivery of acetylcholine and local pressure application in young adult (6,7 months) and old (22,25 months) mice, using pharmacological inhibitors. The cutaneous vasodilator responses induced by acetylcholine and local pressure application were dependent upon NO and PG pathways in young adult mice, whereas they were EDHF-dependent in old mice. EDHF appears to serve as a back-up mechanism when ageing reaches pathological states in terms of the ability for NO and PG to relax cutaneous microvessels, allowing for persistent cutaneous vasodilatator responses in old mice. However, as a back-up mechanism, EDHF did not completely restore cutaneous vasodilatation, since endothelial responses were reduced in old mice compared to young adult mice. [source] Re: An effective method for external pressure application in anterior epistaxisCLINICAL OTOLARYNGOLOGY, Issue 4 2008V. Visvanathan No abstract is available for this article. [source] Hydrostatic low-range pressure applications of the Paris,Edinburgh cell utilizing polymer gaskets for diffuse X-ray scattering measurementsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2007Karena W. Chapman The use of a polymeric Torlon (polyamide,imide) gasket material in a Paris,Edinburgh pressure cell for in situ high-pressure X-ray scattering measurements is demonstrated. The relatively low bulk modulus of the gasket allows for fine control of the sample pressure over the range 0.01,0.42,GPa. The quality of the data obtained in this way is suitable for Bragg and pair distribution function analysis. [source] | ||||||||||