ISSN:1071-5762    

DOI:10.3109/10715769609087994

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The production of semiquinone free radicals has been measured by electron paramagnetic resonance spectroscopy (EPR) in Chinese hamster ovary cells in which 7-hydroxy daunorubicin aglycone had been incorporated. The highly lipophilic daunorubicin aglycone was incorporated into the cellular membrane by swirling a cell suspension over a thin layer of daunorubicin aglycone. Thus, the observed semiquinone free radical was likely formed directly in the lipophilic environment of the cellular membrane. The linewidth of the observed EPR signal suggested that a neutral protonated semiquinone species was formed. In the presence of the cell-impermeant paramagnetic line broadening agent chromium(III) oxalate, no detectable signal was observed. This result indicates that even though the semiquinone is embedded in the membrane, it is still partly accessible to the external chromium(III) oxalate. Analysis of chloroform extracts of the cells after EPR experiments indicated that daunorubicin aglycone was extensively metabolized. The results of a growth inhibition assay carried out on cells into which daunorubicin aglycone had been incorporated showed almost no effect on cell growth. This result indicates that in spite of significant daunorubicin aglycone-induced radical formation taking place directly in the cell membrane, little cell damage results.

ISSN:1071-5762    

DOI:10.3109/10715769609087995

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Phenolic porphyrins 1, 4, and 5 form stable phenoxyl radicals 3, 6, and 7 in deoxygenated as well as oxygenated basic solutions. Mechanistic schemes are presented, involving coupled disproportionation and conproportionation reactions, that do not require oxygen involvement in the redox processes leading to phenoxyl radicals.

ISSN:1071-5762    

DOI:10.3109/10715769609087996

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Adenosine is an endogenous cardioprotective substance. The present study examines whether exogenous adenosine attenuates cardiac injury induced by oxida-tive stress. Rat hearts (Langendorff model) were perfused with H2O2(180μM) for 10 min, then recovered for 60 min (n = 10). In other groups adenosine 55μM, 110μM, or 220μM (n = 10 in each) was given in addition to H2O2throughout perfusion. Control perfusion with Krebs Henseleit only (n=7), adenosine 110μM throughout perfusion (n = 7), and adenosine 110μM as an intervention (n = 7) was performed. The hearts were paced at 320 beats/min. Left ventricular systolic (LVSP) and end-diastolic (LVEDP) pressures were measured together with coronary flow (CF), and left ventricular developed pressure (LVDP = LVSP - LVEDP) was calculated. H2O2decreased LVSP from 105±8 to 60±5 mmHg (mean±SEM) after 10 min infusion (p<0.008). Adenosine did not attenuate the decrease of LVSP. LVEDP increased from 0 to 59±10 mmHg (p<0.004) and 62±11 mmHg 5 and 15 min after end of infusion of H2O2, respectively. Neither 55μM nor 220μM adenosine inhibited the H2O2-induced increase of LVEDP. Adenosine 110μM attenuated the increase after 15 (15±4 mmHg, p<0.004) and 25 min observation (26±7 mmHg, p<0.012). Adenosine did not attenuate the reduction of LVDP. CF initially increased during infusion of H2O2, thereafter decreased. Hearts given adenosine had higher basal CF, and CF did not increase after H2O2. Control perfusion with adenosine, given throughout perfusion or as an intervention, increased CF and tended to increase LVSP. In summary, adenosine did not inhibit H202-induced depression of contractility or reduction of CF. One concentration of adenosine (110μM) attenuated H2O2-induced impairment of relaxation. Exogenous adenosine does not have an important influence on functional injury caused by exogenous oxidants.

ISSN:1071-5762    

DOI:10.3109/10715769609087997

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The influence of anticancer agents on signal transduction for reactive oxygen generation was examined in polymorphonuclear leukocytes (PMN). Inositol 1,4,5-trisphosphate and diacyl glycerol levels in formyl-methionyl-leucyl-phenylalanine (FMLP)-stimulated PMN were decreased by cis-diammine-dichloroplatinum (CDDP), 5-fluorouracil (5-FU),137Cs, and peplomycin (PLM, a bleomcin analog) in this order. Intracellular calcium ([Ca2+]i) level and protein kinase C (PKC) activity in the membrane after phorbol myristate acetate (PMA) stimulation were decreased by 5-FU and CDDP but not by137Cs and, in contrast, were increased by PLM. The level of [Ca2+]iwas decreased by 8 h treatment with 5-FU and CDDP. 5-FU and CDDP inhibited tyrosine phoshorlation of 83-kDa and 115-kDa proteins, however137Cs did not inhibit their phos-phorylation and PLM enhanced the tyrosine phosphorylation. Short term (≤4 h) treatment with PLM, 5-FU and CDDP enhanced respiratory burst of PMN, whereas long term (8 h) treatment, as well as radiation, suppressed reactive oxygen generation from PMN in a dose dependent manner. Genistein supressed chemiluminescence in 5-FU-, CDDP-, and137Cs-pretreated PMN to a greater extent than it did in PLM-pretreated PMN, however near suppression of chemiluminescence by staurosporine, 4-bromophenyl bromide and methionine was observed in PMN pre-treated with these agents. In conclusion, these results indicate that long term treatment of PMN with 5-FU and CDDP inhibit respiratory burst, suppressing intracellular calcium mobilization, PKC translocation and tyrosine kinase activation, in adverse, short term treatment with PLM enhances PKC translocation and tyrosine kinase activation, but inhibits myeloperoxidase (MPO) activity, and radiation causes weak inhibition of signal transduction for respiratory burst.

ISSN:1071-5762    

DOI:10.3109/10715769609087998

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

It was shown that the iron-selective chelator desferal (desferrioxamine mesylate: DFO) can reduce Cu(II) as judged by measuring the formation of the complex between Cu(I) and a specific chelator for this species, neocuproine (NC), in phosphate buffer. It was found that under optimal conditions, 3 moles of Cu(II) could be reduced per mole of DFO. Studies of the kinetics of Cu(II) reduction by DFO revealed that the rate of Cu(II) reduction by DFO was considerably slower than that by ascorbate. In the case of both reductants, even in the absence of NC, Cu(I) complexes remained in aqueous solutions for at least 30 min. DFO could also reduce Cu complexed to histidine. The results presented highlight the interpretive dangers which can arise in studies involving multiple transition metals, especially in the presence of multiple chelators. Specifically, when desferal is used, it is important to be aware that any copper present may become reduced, and that any Cu(I) formed might participate in ongoing redox reactions.

ISSN:1071-5762    

DOI:10.3109/10715769609087999

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Serotonin (5-hydroxytryptamine, 5-HT) significantly and dose-dependently suppressed the luminol-enhanced chemiluminescence (CL) signal generated by polymorphonuclear leukocytes (PMN) activated with phorbol myristate acetate (PMA), but did not modify either lucigenin-enhanced CL or the reduction of super-oxide dismutase-inhibitable cytochrome c. Moreover, stimulation of PMNs previously incubated with 5-HT resulted in a threefold increase in 5-HT equivalents bound to the proteins of PMN. The addition of catalase or sodium azide substantially reduced this binding. The present results suggest that 5-HT metabolism is mediated by H2O2and myeloperoxidase (MPO) released by activated PMNs. Hence 5-HT could lower the bactericidal function of these cells by competition with hypochlorite formation from halides and MPO/H2O2.

ISSN:1071-5762    

DOI:10.3109/10715769609088000

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

The purpose of this experiment was to study the efficiency of protective substances on the effects of cosmic radiation in space on low density lipoproteins. This environment induced modifications in LDL consisting of an increase of lipid peroxidation markers (hydroperoxides, thiobarbituric acid reactive substances). In contrast, apo B was not affected by cosmic radiation as shown by the stability of the trinitrobenzenesulfonic acid reactivity and the tryptophan content. Furthermore, oxidation of LDL was partially inhibited by the addition of cysteamine or / and probucol before the spaceflight experiment. The hydroperoxide formation was almost completely inhibited by cysteamine. It was concluded that antioxidants can exert a protective effect against peroxidative stress induced by the space environment.

ISSN:1071-5762    

DOI:10.3109/10715769609088001

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

ISSN:1071-5762    

DOI:10.3109/10715769609088002

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor