Search results for "Probe"
showing 10 items of 534 documents
Probes for studying cholesterol binding and cell biology.
2011
Cholesterol is a multifunctional lipid in eukaryotic cells. It regulates the physical state of the phospholipid bilayer, is crucially involved in the formation of membrane microdomains, affects the activity of many membrane proteins, and is the precursor for steroid hormones and bile acids. Thus, cholesterol plays a profound role in the physiology and pathophysiology of eukaryotic cells. The cholesterol molecule has achieved evolutionary perfection to fulfill its different functions in membrane organization. Here, we review basic approaches to explore the interaction of cholesterol with proteins, with a particular focus on the high diversity of fluorescent and photoreactive cholesterol prob…
ESR study of the liposome membrane physical parameters in the heating-cooling cycles.
1998
Abstract Changes of dynamic and structural parameters of egg yolk lecithin (EYL) liposome membranes in the heating-cooling cycles have been studied using the E S R spin probe method. The investigations were conducted in the range of temperatures from -18 °C to +60 °C. It has been found that in the range of temperatures -15 °C to +45 °C in both the heating and the cooling run the spectroscopic parameters changed practically along the same curve (reversible changes). However, after exceeding this range of temperatures one of the parameters (partition coefficient of the spin probe 2,2,6,6 -tetramethylpiperidine -1-oxyl; TEMPO) changed along a closed curve, showing the phenomenon of thermal h…
Highly Selective Detection of Nerve‐Agent Simulants with BODIPY Dyes
2014
Two chromo-fluorogenic probes, each based on the boron dipyrromethene core, have been developed for the detection of nerve-agent mimics. These chemosensors display both a color change and a significant enhancement of fluorescence in the presence of diethylcyanophosphonate (DCNP) and diisopropylfluorophosphate (DFP). No interference from other organophosphorus compounds or acids has been observed. Two portable chemosensor kits have been developed and tested to demonstrate its practical application in real-time monitoring.
α4-1 Subunit mRNA of the nicotinic acetylcholine receptor in the rat olfactory bulb: cellular expression in adult, pre- and postnatal stages
1996
In addition to their role in signal transduction, nicotinic acetylcholine receptors have been shown in vi-tro to be involved in neuronal growth cone regulation during development. This idea is supported by recent histochemical findings showing that iso- and archicortical nicotinic alpha4-1 receptor mRNA expression precedes cholinergic fiber ingrowth. To test whether this also holds true for rhinencephalic parts of the telencephalon, we have studied the olfactory bulb by digoxigenin-mediated in situ hybridization, using an alpha4-1 isoform-specific riboprobe and an alkaline-phosphatase-based detection system. Development is characterized by early intense alpha4-1 mRNA expression (embryonic d…
Micro-Raman characterization of graphene grown on SiC(000-1)
2014
Graphene (Gr) was grown on the C face of 4H-SiC under optimized conditions (high annealing temperatures ranging from 1850 to 1950°C in Ar ambient at 900 mbar) in order to achieve few layers of Gr coverage. Several microscopy techniques, including optical microscopy (OM), ?Raman spectroscopy, atomic force microscopy (AFM) and atomic resolution scanning transmission electron microscopy (STEM) have been used to extensively characterize the lateral uniformity of the as-grown layers at different temperatures. ?Raman analysis provided information on the variation of the number of layers, of the stacking-type, doping and strain.
ChemInform Abstract: Relaxation Phenomena of a Triplet Spin Probe in Glassy and Crystalline o-Terphenyl.
2010
The authors used quinoxaline in its photoexcited triplet state as a spin probe in order to measure the spin-lattice relaxation rate in o-terphenyl glass as a function of temperature. They found a power law with an exponent close to 2. Since o-terphenyl can easily be crystallized, they investigated the crystal, too. Below 3.5 K the spin is highly polarized, contrary to the behavior in the glass, where it reaches thermal equilibrium down to the lowest temperatures of their experiment (1.4 K). Around 3.5 K the polarization in the crystal vanishes. Above it appears with opposite sign due to thermal equilibration.
Sensitive determination of probenecid in urine samples by reversed-phase liquid chromatography and UV-visible detection using solid-phase extraction …
1993
This study describes a rapid method for the determination of probenecid in human urine by liquid chromatography with UV detection at 254 nm, after clean-up through a C8 solid-phase extraction column. Liquid chromatography was carried out on a C18-bonded phase using an acetonitrile-acetate buffer (pH=4) gradient elution. Ethacrynic acid was used as internal standard. The system has been applied to the determination of probenecid in the 0.10–100.0 μg/ml concentration range; the limit of detection was 5 ng/mL.
Photo-DHEA--a functional photoreactive dehydroepiandrosterone (DHEA) analog.
2011
Abstract The steroid hormone dehydroepiandrosterone (DHEA) has beneficial effects on vascular function, survival of neurons, and fatty acid metabolism. However, a specific receptor for DHEA has not been identified to date. Here, we describe the synthesis of a photoreactive DHEA derivative (Photo-DHEA). In Photo-DHEA, typical characteristics of DHEA are conserved: (i) a “planar” tetracyclic ring system with a Δ 5 double bond, (ii) a 3β-hydroxyl group, and (iii) a keto group at C17. In cell-based assays, Photo-DHEA showed the same properties as DHEA. We conclude that Photo-DHEA is suitable for radioiodination to yield a tool for the identification of the elusive DHEA receptor.
Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft
2016
Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain …
Iron oxides nanoparticles and titanate nanotubes dedicated to multimodal imaging and anticancer therapy
2013
The new implementations of nanoparticles in the medical field are one of the essential factors of the medical progress expected at the beginning of this XXIst century. Thus, the domain of the medical imaging is also affected by this technological evolution. This work consisted in developing theranostic probes with iron oxides nanoparticles (SPIO) and titanate nanotubes (TiONts) for multimodal imaging (magnetic/nuclear or magnetic/optical) and also possessing a therapeutic effect (hyperthermia/PDT or radiosensitization/PDT).The titanate nanotubes of this study have an average length of about 150 nm and were obtained by Kasuga's hydrothermal synthesis. These nanotubes present an outside diame…