Results 1 - 10 of 1786
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[en] The cephalosporin antibiotic cephalotin has the ability to prolong and intensify the chemiluminescence derived from the cobalt(II)-luminol-hydrogen peroxide system. This is believed to result from the formation of a peroxide complex of cephalotin which is longer lived than the superoxide ion in aqueous solution. It can be used as the basis for the determination of cephalotin in the range of 0.4-400 μg ml-1. (author). 11 refs.; 1 fig
[en] Involvement of coenzyme Q (CoQ) in anti-oxydant activities, in addition to its major redox role, has frequently been suggested in recent years. In order to elucidate if CoQ could really be engaged in scavenging free radicals produced endogenously in a biological system, an experimental system was developed in which beef heart mitochondria in the presence of a saturating NADH concentration and of rotenone produce free radicals. The presence of oxygen-reactive forms was easily detected by a luminol-dependent chemiluminescence process. The chemi-luminescence assay showed that short-chain CoQ homologues can act as pro-oxidants, enhancing free radical effects, while exogenous coenzyme Q10 could scavenge free radicals, especially at very low concentration. In this system, exogenous CoQ10 was more effective than α-tocopherol at the same concentration in scavenging free radicals. The molecular mechanism that leads to this activity is still unclear, but these results are of biochemical importance because they indicate that CoQ may act as an anti=oxidant in situations mimicking physiopathological conditions. This direct chemiluminescent method is promising for studies of biochemical processes which involve active oxygen species. (author). 24 refs.; 4 figs
[en] A general and practical chemiluminescence (CL) biosensing platform for detection of tumor marker prostate-specific antigen (PSA) as a model analyte was developed for the first time based on the excellent catalytic performance of bimetallic Au-Ag core-shell nanoparticales ([email protected] NPs) on luminol-K3Fe(CN)6 CL system. The [email protected] NPs were synthesized by a simple and green aqueous phase successive reduction method. The prepared [email protected] NPs with remarkable synergistic catalytic activity effect could significantly catalyze luminol-K3Fe(CN)6 CL reaction to produce a great CL enhancement. Based on this synergistic catalytic activity, a luminol-K3Fe(CN)6[email protected] NPs CL system combined with immunoassay was designed for the sensitive detection of PSA. In this protocol, the [email protected] NPs were modified with anti-PSA-antibody ([email protected] NPs) to specifically capture target molecules PSA. In the presence of PSA, a non-competitive immunoreaction occurred between [email protected] NPs and PSA to form an immnunonanoshperes ([email protected] NPs). The results show that the CL catalytic ability of the immnunonanospheres decreased with the PSA concentration increasing. And the quenching degree of CL signals is proportional to the logarithm of PSA concentration in the range of 0.1 pg mL−1–100.0 ng mL−1. Thanks to the fine performance of the [email protected] NPs, the detection limit of the method is down to 0.047 pg mL−1 (S/N = 3). Moreover, the applicability of the present method was successfully applied for PSA determination in human serum samples with recoveries of 86.1–112.5%, demonstrating great promise for application in biochemical analysis.
[en] The formation of reactive O2 species in the pancreas of pigs after induction of necrotizing or oedematous pancreatitis was studied by means of luminol- and lucigenin-sensitized chemiluminescence. The effect of 2,2-dimethyl-4-methanesulphonic acid-1,2-dihydroquinoline in combination with Trasylol and ascorbic acid was studied in vivo. This combined therapy leads to a reduction in the chemiluminescence response by 50-70% with prevention of pancreatogenic shock and multiple organ failure by improvement of the gluthathione status. A combination of radical traps, kallikrein inhibitors and natural antioxidative sub-stances is an efficient alternative therapy in cases of acute pancrea-titis. (author). 10 refs.; 5 figs
[en] Chemiluminescence is found to be generated by action of lucigenin or hexacyanoferrate(III) on tetracyclines. The reaction with lucigenin exhibits chemiluminescence after alkaline degradation of tetracyclines to the corresponding iso derivatives. The reaction with hexacyanoferrate (III) occurs after acidic degradation of tetracyclines to corresponding anhydro derivatives. The chemiluminescence reaction takes place in alkaline medium, and allows the development of a continuous-flow method for the determination of 1.00-10.0 μgml-1 oxytetracycline and doxycycline. When applied to commercial formulations, the procedure was relatively free from interferences from common excipients. The results obtained for the assay of dosage forms compared well with those obtained by the official methods and demonstrated good accuracy and precision. (author). 32 refs.; 5 figs.; 6 tabs
[en] A number of staining techniques on Western blots were compared with respect to sensitivity, background staining and practical applicability After electrophoresis of a rat microsomal preparation, followed by blotting and incubation of a primary antibody against a purified cyto-chrome P-450 fraction, enzyme-labelled second antibodies were used for detection. Both colorimetric and chemiluminescent detection methods were investigated. It appeared that chemiluminescence detection of horseradish peroxidase was the most sensitive method, followed by chemiluminescence detection of xanthine oxidase. Horseradish peroxidase with colorimetric detection was also fairly sensitive and easier to use than chemiluminescence detection. Alkaline phosphatase gave the least sensitive method with both colorimetric and chemiluminescence detection. Both horseradish peroxidase and especially alkaline phosphatase showed heavy background staining, in contrast to xanthine oxidase, where no background staining was observed even after overnight exposure. (author). 13 refs.; 2 figs.; 1 tab
[en] Multi-layer films consisting of oxalate, hydrogen peroxide and various fluorescers are mechanically activated to emit the visible and near-infrared chemiluminescent light. By optimization of composition and thickness of each layer, chemiluminescence can be long lasting, typically over 30 min. The simple pattern displays have also been demonstrated. - Highlights: • Peroxyoxalate chemiluminescence (CL) from a solid multi-layer film has been achieved. • Visible and near infrared CL occurs through mechanical activation. • The CL light can be long lasting, typically over 30 min. • Simple CL display has been demonstrated by the method of array and print pattern.
[en] The determination of thyrotropin(TSH) is useful in diagnosis of thyroid diseases. And the widely-used method for the determination of thyrotropin is radioimmunoassay so far because of its sensitivity. But its radiohazard and relatively short half-life of isotopes necessitates alternative methods. So many novel non-isotopic immunoassays are developed and now replacing RIA in routine laboratory measurements. We evaluated the enhanced chemiluminescence enzymeimmunoassay (Amerlite, Amersham International plc., U.K.) for the determination of serum TSH. We got good precision result with control sera. Within-assay and between-assay precision revealed less than 10%(C.V.) respectively. And comparision with CLEIA to RIA showed good correlation (y=0.648x + 0.170, r=0.978, y=value of CLEIA, x=values of RIA, n=35). We also got good correlation between singletons and duplicates result from 35 patients sera (y=0.967x + 0.0281, r=0.997, y=values of singletons, x=values of duplicates). We concluded that CLEIA is vary reliable and economic method for the determination of human TSH substitutive for RIA because of its precision and unnecessary duplicate measurements. (Author)
[en] Complete text of publication follows. This work is aimed at demonstrating the potential of the implementation of automatic flow systems in solid-phase spectroscopy (SPS); with this purpose, two automatic systems have been employed, multicommutation and sequential injection analysis (SIA) and a critical comparison of both methodologies has been performed. The implementation of chemiluminescence detection in SPS has been satisfactorily carried out in both methods: a model analyte, 5-aminosalicylic acid, has been selected and it has been determined making use of its chemiluminescence reaction with permanganate retained on a solid support. First, the study of the most appropriate commercial flow-through cell and the optimum conditions for the reaction was performed. Second, the main differences in terms of flow variables and analytical parameters for multicommutation and SIA are stated. Finally, the analyte was determined in pharmaceuticals; in addition, statistical tests were carried out to prove the accuracy of the recovery method and to test that there is no significant difference between the two proposed methods with regard to accuracy and precision.