Search results for "PHOTOCHEMISTRY"
showing 10 items of 2034 documents
On the spectral intermediate at 440 nm formed during mixed function substrate oxidation.
1974
Abstract The spectral shoulder formed at 440 nm in microsomes oxidising hexobarbital and other drugs has been investigated and some of its properties characterised. Hexobarbital, pentobarbital, ethylmorphine and barbital produce this shoulder, while acetanilide, aniline, desmethylimipramine, imipramine, metyrapone and SKF 525-A do not. The formation of the 440 nm shoulder depends on the presence of NADPH and oxygen and is reduced in size when NADH is also present. At saturating substrate concentrations the size of the 440 nm shoulder is correlated to the cytochrome P-450 content. The hexobarbital induced shoulder can be inhibited by drug metabolism inhibitors such as metyrapone, imipramine …
C1-esterase inhibitor reduces infarct volume after cortical vein occlusion.
1999
In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood flow (rCBF) decreased after occlusion, and was about 50% of baseline after 2 h. No difference was noted between experimental groups. Mean arterial blood pressure (MABP) and arterial blood gases were likewise unaffected by the treatment. However, administration of C1-INH had significantly reduced infarct volume by 72%, as evaluated after 5 days survival…
Identification and purification of a stress associated nuclear carbohydrate binding protein (Mr 33000) from rat liver by application of a new photore…
1994
A photoreactive alpha-D-glucose probe has been designed for the specific detection of carbohydrate binding proteins (CBPs). The probe consists of four parts: (i) an alpha-D-glucose moiety; (ii) the digoxigenin tag; (iii) the photoreactive cross-linker; and (iv) the lysyl-lysine backbone. After incubation with lectins in the dark, the probe is activated and cross-linked to the CBPs after being treated by several flashes. Using this method we have identified a new alpha-D-glucose CBP of M(r) = 33,000, termed CBP33, in the nuclei of rats exposed to transient immobilization stress. Monoclonal antibodies were raised against the partially purified protein and subsequently used to enrich CBP33. It…
Kinetic experiments on the synergistic effect of NADH on microsomal drug oxidation.
1974
Abstract1. The synergistic effect of NADH on the NADPH-dependent mixed function oxidation of p-nitroanisole and hexobarbital can be measured both photometrically and by following the substrate-induced oxygen consumption. The increase in reaction rate is about 50% and lasts as long as NADH is present in the microsomal suspension.2. The oxidation of added NADH is increased by hexobarbital, ethylmorphine and SKF 525-A. Lineweaver-Burk transformation of the NADH oxidation rates yields straight lines for xenobiotic substrates suggesting Michaelis constants similar to those obtained from metabolic experiments. NADH oxidation in the absence of NADPH is about half as rapid as in its presence.3. Som…
Photochemically induced, graded cerebral infarction in the mouse by laser irradiation evolution of brain edema
1992
Cerebral infarction was produced in mice by intravenous injection of a photosensitive dye, rose bengal (10 mg/kg), and by focal illumination of the intact skull surface for 3 min with a laser source, operating at 570 nm with power levels of 2, 5, 10, and 20 mW. Location of infarction was made using 2,3,5-triphenyltetrazolium chloride and the time course of edema in the irradiated cerebral hemisphere was evaluated by measuring water, sodium, and potassium content 4, 24, and 72 hr after irradiation. With power levels of 2 and 5 mW, the infarct was restricted to the cortex, whereas with power levels of 10 and 20 mW, it extended to subcortical regions. Increases in water and sodium and decrease…
Effects of Cortical Spreading Depression on Cortical Blood Flow, Impedance, DC Potential, and Infarct Size in a Rat Venous Infarct Model
2000
A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. In 36 rats local CBF, DC potential, and brain tissue impedance were measured continuously for 75 min after vein occlusion. No, 3, or 10 CSD waves were induced by potassium chloride injection during the initial 75 min. Rats were compared for spontaneous CSDs; baseline local CBF, CBF, and impedance response to CSD; and infarct vol…
Electrochemistry and Spectroelectrochemistry of Bismanganese Porphyrin-Corrole Dyads
2011
A series of homobimetallic manganese cofacial porphyrin-corrole dyads were synthesized and investigated as to their electrochemistry, spectroelectrochemistry, and ligand binding properties in nonaqueous media. Four dyads were investigated, each of which contained a Mn(III) corrole linked in a face-to-face arrangement with a Mn(III) porphyrin. The main difference between compounds in the series is the type of spacer, 9,9-dimethylxanthene, anthracene, dibenzofuran, or diphenylether, which determines the distance and interaction between the metallomacrocycles. Each redox process of the porphyrin-corrole dyads was assigned on the basis of spectroscopic and electrochemical data and by comparison…
High Turnover Catalase Activity of a Mixed‐Valence Mn II Mn III Complex with Terminal Carboxylate Donors
2015
The neutral dimanganese(II,III) complex [Mn-2(BCPMP)-(OAc)(2)] [1; BCPMP3- = 2,6-bis({(carboxymethyl)[(1-pyridyl)-methyl] amino} methyl)-4-methylphenolato] has been synthesized and characterized. The complex contains two terminal carboxylate donors. Complex 1 was found to be an effective catalyst for the disproportionation of H2O2 with high catalytic rate and a turnover number of 7500, the highest turnover reported to date for a catalase mimic. The rates and TON were significantly higher than recorded for a dicationic dimanganese( II,III) counterpart ([Mn-2(BPBP)(OAc)(2)]center dot(ClO4)(2), 2; BPBP- = 2,6-bis{[bis(2-pyridylmethyl)amino]methyl}-4-butylphen-olato), which lacks the terminal c…
Design principles of chemiluminescence (CL) chemodosimeter for self-signaling detection: Luminol protective approach
2014
Chemiluminescence (CL) sensors can provide convenience and high sensitivity because they do not require an external excitation light source to produce a fluorescence signal. However, most CL based detection systems do not have a built-in self-signaling process, leading to inefficient and complex protocols due to the required multistep cascade reactions. Here, we develop a CL based sensory system with a built-in self-signaling feature by adapting the chemodosimeter concept. We found that a masking group incorporated to luminol efficiently suppresses the CL of luminol and that selective removal of the masking group by a target analyte can turn on the CL process, generating a sensitive fluores…
Electron Ionization Induced Fragmentation of some 3-Aroylamino-5-Methyl-1,2,4- Oxadiazoles and 3-Acetylamino-5-Aryl-1,2,4-Oxadiazoles
2017
: Background and objectives. 1,2,4-Oxadiazoles show a high reactivity and represent starting compounds for the synthesis of several other heterocycles. Some their derivatives can give the so called Boulton-Katritzky Reactions (BKR) which opens the way to the synthesis of several azoles. For this reason we have registered the mass spectra of several 3-aroylamino-5-methyl-1,2,4-oxadiazoles and 3-acetylamino-5-aryl-1,2,4-oxadiazoles. Methods and results. Thus, studying the mass spectra of the isomeric couple 3-benzoylamino-5-methyl-1,2,4-oxadiazole (1A) and 3-acetylamino-5-phenyl-1,2,4-oxadiazoles (1B) we have observed that MIKE and CID MIKE spectra of their molecular ions and of the [M – CH2C…