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Background Fluorescence (background + fluorescence)
Selected AbstractsDirect evidence of nitric oxide release from neuronal nitric oxide synthase activation in the left ventricle as a result of cervical vagus nerve stimulationTHE JOURNAL OF PHYSIOLOGY, Issue 12 2009Kieran E. Brack Information regarding vagal innervation in the cardiac ventricle is limited and the direct effect of vagal stimulation on ventricular myocardial function is controversial. We have recently provided indirect evidence that the anti-fibrillatory effect of vagus nerve stimulation on the ventricle is mediated by nitric oxide (NO). The aim of this study was to provide direct evidence for the release of nitric oxide in the cardiac ventricle during stimulation of the efferent parasympathetic fibres of the cervical vagus nerve. The isolated innervated rabbit heart was employed with the use of the NO fluorescent indicator 4,5-diaminofluorescein diacetate (DAF-2 DA) during stimulation of the cervical vagus nerves and acetylcholine perfusion in the absence and presence of the non-specific NO synthase inhibitor NG -nito- l- arginine (l- NNA) and the neuronal NO synthase selective inhibitor 1-(2-trifluormethylphenyl)imidazole (TRIM). Using the novel fluorescence method in the beating heart, we have shown that NO-dependent fluorescence is increased by 0.92 ± 0.26, 1.20 ± 0.30 and 1.91 ± 0.27% (during low, medium and high frequency, respectively) in the ventricle in a stimulation frequency-dependent manner during vagus nerve stimulation, with comparable increases seen during separate stimulation of the left and right cervical vagus nerves. Background fluorescence is reduced during perfusion with l- NNA and the increase in fluorescence during high frequency vagal stimulation is inhibited during perfusion with both l- NNA (1.97 ± 0.35% increase before l- NNA, 0.00 ± 0.02% during l- NNA) and TRIM (1.78 ± 0.18% increase before TRIM, ,0.11 ± 0.08% during TRIM). Perfusion with 0.1 ,m acetylcholine increased NO fluorescence by 0.76 ± 0.09% which was blocked by l- NNA (change of 0.00 ± 0.03%) but not TRIM (increase of 0.82 ± 0.21%). Activation of cardiac parasympathetic efferent nerve fibres by stimulation of the cervical vagus is associated with NO production and release in the ventricle of the rabbit, via the neuronal isoform of nitric oxide synthase. [source] A parylene-based dual channel micro-electrophoresis system for rapid mutation detection via heteroduplex analysis,ELECTROPHORESIS, Issue 18 2008Sertan Sukas Abstract A new dual channel micro-electrophoresis system for rapid mutation detection based on heteroduplex analysis was designed and implemented. Mutation detection was successfully achieved in a total separation length of 250,,m in less than 3,min for a 590,bp DNA sample harboring a 3,bp mutation causing an amino acid change. Parylene-C was used as the structural material for fabricating the micro-channels as it provides conformal deposition, transparency, biocompatibility, and low background fluorescence without any surface treatment. A new dual channel architecture was derived from the traditional cross-channel layout by forming two identical channels with independent sample loading and waste reservoirs. The control of injected sample volume was accomplished by a new u-turn injection technique with pull-back method. The use of heteroduplex analysis as a mutation detection method on a cross-linked polyacrylamide medium provided accurate mutation detection in an extremely short length and time. The presence of two channels on the microchip offers the opportunity of comparing the sample to be tested with a desired control sample rapidly, which is very critical for the accuracy and reliability of the mutation analyses, especially for clinical and research purposes. [source] A Graphene Nanoprobe for Rapid, Sensitive, and Multicolor Fluorescent DNA AnalysisADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Shijiang He Abstract Coupling nanomaterials with biomolecular recognition events represents a new direction in nanotechnology toward the development of novel molecular diagnostic tools. Here a graphene oxide (GO)-based multicolor fluorescent DNA nanoprobe that allows rapid, sensitive, and selective detection of DNA targets in homogeneous solution by exploiting interactions between GO and DNA molecules is reported. Because of the extraordinarily high quenching efficiency of GO, the fluorescent ssDNA probe exhibits minimal background fluorescence, while strong emission is observed when it forms a double helix with the specific targets, leading to a high signal-to-background ratio. Importantly, the large planar surface of GO allows simultaneous quenching of multiple DNA probes labeled with different dyes, leading to a multicolor sensor for the detection of multiple DNA targets in the same solution. It is also demonstrated that this GO-based sensing platform is suitable for the detection of a range of analytes when complemented with the use of functional DNA structures. [source] Upconverting Nanoparticles: The Active-Core/Active-Shell Approach: A Strategy to Enhance the Upconversion Luminescence in Lanthanide-Doped Nanoparticles (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Mater. Lanthanide-doped nanoparticles capable of (up)converting near-infrared (NIR) light to higher energies via an anti-Stokes process known as upconversion have demonstrated extraordinary potential in biological applications on the virtue that background fluorescence is near-zero. To maximize the intensity of the upconverted luminescence in lanthanide-doped nanoparticles, Vetrone et al. utilize a core/active-shell architecture where the active-shell readily absorbs NIR light and transfers it to the active luminescent core, thereby increasing the upconversion emission, as described on page 2924. [source] Analysis of several fluorescent detector molecules for protein microarray useLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2003Rick Wiese Abstract The utility of several streptavidin-linked fluorescent detector molecules was evaluated on two protein microarray platforms. Tested detector molecules included: Alexa Fluor 546; R-phycoerythrin (RPE), orange fluospheres; Cy3-containing liposomes (Large Unilamellar Vesicles, LUV) labelled with Cy3; and an RPE,antibody complex. The two array architectures tested consisted of an array of murine Fc,biotin and an array of murine IgG (the murine IgG array was probed with a biotinylated rabbit anti-murine IgG). These platforms allowed for the direct comparison of detector utility by detector recognition of array-bound biotin. All of the fluorescent detectors examined demonstrated utility on each of the array platforms. For the Fc,biotin array, detector signal intensity (background adjusted) was as follows: RPE,antibody complex,>,fluospheres,>,RPE,>,liposomes,>,Alexa 546: for the IgG array: RPE/antibody complex,>,RPE,>,fluospheres,>,Alexa546,>,liposomes. The RPE,antibody complex fluoresced 67% and 150% more intensely than the next closest detector molecule for the Fc,biotin and the murine IgG arrays, respectively. A marked increase in background fluorescence (as compared to RPE alone) did not accompany the increase in signal intensity gained through RPE,antibody complex use (a true increase in signal:noise ratio). These results suggest that the RPE,antibody complex is superior to other molecules for fluorescent detection of analytes on protein microarrays. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||