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991.
Oudot A Martin C Busseuil D Vergely C Demaison L Rochette L 《Free radical biology & medicine》2006,40(12):2214-2222
The aim of our study was to examine in rats, age-related differences in myocardial ischemic recovery and to determine the possible relationship with modification of cardiac and vascular oxidative stress. Isolated perfused hearts from young (2 months), adult (6 months), and old (21 months) Wistar rats were subjected to a ischemia–reperfusion sequence. Vascular histomorphological analyses were performed and NADPH oxidase was studied. The expression of angiotensin AT1 receptors was evaluated using immunostaining. During the preischemic period, but also after ischemia, an aged-related decrease in myocardial functional parameters was observed, and was associated with an increased release of reactive oxygen species. In aortas, the activity and expression of NADPH oxidase increased with age according to the ESR, fluorescence microscopy, and immunohistochemistry; the NADPH oxidase involved was localized in endothelial cells. We found an age-related increase in the expression of endothelial angiotensin AT1. Our study suggests that myocardial function and adaptation to ischemia–reperfusion declined during aging and are related to a higher level of oxidative stress. Endothelial NADPH oxidase is a major contributor to age-related cardiovascular deterioration. One of the regulators of vascular NADPH oxidase activity, the renin–angiotensin system, may be involved in the modulation of vascular superoxide production during the aging process. 相似文献
992.
Ionita P 《Free radical research》2006,40(1):59-65
This work describes the synthesis and characterisation of some novel hybrid molecules which contains in the same molecule a free radical moiety of hydrazyl type and a spin-trap moiety of nitrone type. The new compounds synthesized have multiple and easy to follow spectroscopic properties, making them useful as sensors or probes in radical chemistry. The new class of hydrazyl-nitrone molecules can act, in a single step process, as both generator and spin-trap of short-lived radicals. The hybrid molecules can be also involved in acid-base or redox processes, and the chemical processes can be easily monitored by visible or electron paramagnetic resonance spectroscopy. The excellent generator and trap properties recommend them as valuable sensors and probes in radical chemistry. 相似文献
993.
One of the reasons of rheumatoid arthritis (RA) development is widely recognized the relation of free radical reactions in tissue injuries. The aim of this study was to evaluate the location where in vivo free radical reactions was enhanced in adjuvant arthritis (AA) model rats using in vivo electron spin resonance (ESR)/nitroxyl spin probe technique. The signal decay after intravenous injection of spin probe was enhanced in AA than that in control and suppressed by the pre-treatment of dexamethasone (DXT). Interestingly, the decay in joint cavity occurred prior to paw swelling of AA and suppressed by a simultaneous injection of free radical scavengers, indicating that the enhancement of free radical reactions in joint cavity of AA rats. This technique would be useful tool to determine the location of the enhanced free radical reactions and evaluate the activity of antioxidant medicine with non-invasive real-time measurement. 相似文献
994.
Liu ZQ 《Cell biochemistry and biophysics》2006,44(2):233-239
Vitamin E involves a group of tocopherols and tocotrienols, in which α-tocopherol with the highest biological activity plays
a more efficient role in advanced lesions with aged oxidized tissues. However, the results of the present study reveal that
a large amount of endogenous α-tocopherol in human low-density lipoprotein (LDL) in the absence of any other antioxidants
may initiate additional free radical propagation under low concentration of free radical initiator (i.e., 2,2′-azobis(2-amidinopropane
hydrochloride) [AAPH], a water-soluble free radical source) to peroxide polyunsaturated fatty acids in LDL in the manner of
α-tocopherol-mediated peroxidation (TMP). Whether the addition of high concentration of exogenous α-tocopherol to human erythrocytes
under low concentration of AAPH can also drive TMP is the concern in this research work. Moreover, the hemolysis extent of
human erythrocytes peroxidized by AAPH is followed easily by the determination of the hemoglobin outside the erythrocytes.
A series of observations on various concentrations of AAPH-induced hemolysis in the presence of various concentrations of
exogenous α-tocopherol demonstrates that the high concentration of exogenous α-tocopherol, coupled with low concentration
of AAPH, can initiate TMP in the free-radical-induced peroxidation of human erythrocytes system as well. This result provides
direct evidence to support TMP theory and expands its application into in vitro erythrocytes system. 相似文献
995.
纤维素酶提取红景天总黄酮的研究 总被引:5,自引:0,他引:5
以总黄酮为考察指标,确定纤维素酶提取红景天有效成分的最佳工艺.研究酶解条件对总黄酮浸出率的影响,并对不同提取方法的提取效果和粗提物的DPPH清除活性进行了比较.纤维素酶提取法的最佳工艺条件为:加酶量为1.95%(以原料干重计),液料比为70∶1(mL∶g),pH值为5.5,酶解温度为40℃,酶解时间为5 h,红景天总黄酮的浸出率为4.385%.酶解技术可明显提高红景天总黄酮的浸出率,粗提物得率高且DPPH清除活性较强. 相似文献
996.
997.
Three 1-D transition metal-nitronyl nitroxide radical complexes with dicyanoaurate(I) bridges, [M(NIT3py)2][Au(CN)2]2 [NIT3py = 2-(3′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, M = Mn, Co, Zn (1-3)], were synthesized and structurally characterized. Three compounds are all isostructural in monoclinic, C2/c space group with Z = 4. The [Au(CN)2]− anions link [M(NIT3py)2] units via μ2-bridging mode, leading to a linear coordination chain. The M(II) ion adopts a distorted octahedral geometry with four N atoms from [Au(CN)2]− groups and two pyridyl-N atoms from NIT3py ligands. The magnetic behavior shows that the couplings are both weak antiferromagnetic between Mn(II) and NIT3py and between Co(II) and NIT3py. 相似文献
998.
Ildikó Seres Gabriella Fóris Zsuzsa Varga Béla Kosztáczky Andrea Kassai Zoltán Balogh Péter Fülöp György Paragh 《The Journal of membrane biology》2006,214(1-2):91-98
Angiotensin II (Ang II) is able to induce free radical generation in neutrophils, which is more elevated in neutrophils of
patients with hypercholesterolemia (HC). In addition, the signal processing through angiotensin I (Ang I) receptors is altered.
In present study, we compared the Ang II-triggered free radical generation of neutrophils obtained from patients with relatively
isolated forms of metabolic syndrome (MS) with membrane-bound cholesterol content and membrane fluidity. We determined the
enhancement of Ang II-induced superoxide anion and leukotriene C4 (LTC4) generation, membrane fluidity and cell-bound cholesterol content of neutrophils obtained from 12 control subjects, 11 patients
with obesity (Ob), 10 patients with type 2 diabetes mellitus (t2-DM) and 12 patients with HC. The alteration of signal processing
was studied after preincubation with different inhibiting drugs. Superoxide anion, LTC4 production and membrane rigidity were increased in the following order: control < Ob < t2-DM < HC. Both Ang II-induced superoxide
anion and LTC4 generation were decreased in control cells by pertussis toxin and fluvastatin (Flu), whereas in each patient group, mepacrin,
verapamil and Flu were effective, suggesting alterations in signal pathways, which may be attributed to isoprenylation. The
enhancement of superoxide anion and LTC4 generation correlated significantly with membrane rigidity, independently from the experimental groups and membrane-bound
cholesterol content. Membrane rigidity of neutrophils, obtained from patients with MS, plays a role in Ang II-induced free
radical generation independent of intracellular cholesterol homeostasis. 相似文献
999.
对金顶侧耳Pleurotus citrinopileatus胞内多糖的热水浸提工艺进行研究,并研究了该多糖的抑菌活性以及对超氧阴离子自由基和亚硝基的清除作用。结果表明,金顶侧耳胞内多糖的最佳提取工艺为:提取温度60℃,液料比100:1,时间4h,此条件下多糖提取率可达17.65%。该多糖对埃希氏大肠杆菌和金黄色葡萄球菌均有抑制作用且对超氧阴离子自由基和亚硝基有较强的清除作用,说明该多糖具有明显的生物活性。 相似文献
1000.
We investigated the effects of two flavonoids quercetin and dihydroquercetin (DHQ), which have different solubilities and antioxidant capacities, on hemolysis and platelet aggregation in human blood. Exposure of human red blood cells (RBCs) to free radicals generated by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) for 2 h resulted in 63.5 ± 3.9% hemolysis (vehicle: 0.3 ± 0.4%). Pre-incubation of RBCs with lipid-soluble quercetin and water-soluble DHQ for 30 min significantly reduced the AAPH-induced hemolysis to 3.6 ± 1.5% and 32.5 ± 5.6% respectively. In contrast, quercetin and DHQ were similarly effective in reducing phospholipase C-induced hemolysis (37.2 ± 9.1% and 45.4 ± 10.0% versus vehicle 75.7 ± 5.2%, P < 0.001). Pre-incubation with quercetin, but not DHQ, inhibited the aggregation of platelets by adenosine diphosphate. DHQ was more potent than quercetin in inhibiting superoxide produced by xanthine oxidase. These results suggest that the antihemolytic effects of flavonoids may not be directly mediated by removal of free radicals and may likely be due to their interaction with cell membrane. 相似文献