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排序方式: 共有268条查询结果,搜索用时 703 毫秒
91.
Low doses of selenium specifically stimulate the repair of oxidative DNA damage in LNCaP prostate cancer cells 总被引:1,自引:0,他引:1
de Rosa V Erkekoğlu P Forestier A Favier A Hincal F Diamond AM Douki T Rachidi W 《Free radical research》2012,46(2):105-116
Epidemiological studies have demonstrated an inverse relationship between selenium (Se) intake and cancer incidence and/or mortality. However, the molecular mechanisms underlying the cancer chemopreventive activity of Se compounds remain largely unknown. The objective of this study was to investigate the effect of low doses of Se on the stimulation of DNA repair systems in response to four different qualities of DNA damage. P53-proficient LNCaP human prostate adenocarcinoma cells were grown either untreated or in the presence of low concentrations of two Se compounds (30° nM sodium selenite, or 10 μM selenomethionine) and exposed to UVA, H2O2, methylmethane sulfonate (MMS) or UVC. Cell viability as well as DNA damage induction and repair were evaluated by the alkaline Comet assay. Overall, Se was shown to be a very potent protector against cell toxicity and genotoxicity induced by oxidative stress (UVA or H2O2) but not from the agents that induce other types of deleterious lesions (MMS or UVC). Furthermore, Se-treated cells exhibited increased oxidative DNA repair activity, indicating a novel mechanism of Se action. Therefore, the benefits of Se could be explained by a combination of antioxidant activity, the reduction in DNA damage and the enhancement of oxidative DNA repair capacity. 相似文献
92.
We have investigated the temperature-dependent interaction of the porins OmpF from Paracoccus denitrificans and OmpG from Escherichia coli with lipid molecules after reconstitution in lecithin. Effects of incubation at increased temperatures on activity were tested by functional experiments for OmpG and compared with previously published results of OmpF in order to understand the activity loss of OmpF with monomerization. Protein-lipid interaction was monitored by different reporter groups both from lipid molecules and from protein. OmpF loses its activity by approximately 90% at 50 degrees C while OmpG does not show a temperature-dependent change in activity between room temperature and 50 degrees C. The interaction between OmpF and lipid molecules is severely altered in a two-step mechanism at 55 and approximately 75 degrees C for OmpF. The first step is attributed to changes in the degree of interaction between the aromatic girdle of OmpF and the interfacial region of the lipid bilayer, leading to monomerization of this trimeric porin. The second step at 75 degrees C is attributed to the changes in lipid-porin monomer interaction. Around 90 degrees C, reconstituted porin aggregates. For OmpG, changes in lipid-protein interaction were observed starting from approximately 80 degrees C because of temperature-induced breakdown of its folding. This study provides deeper understanding of porin-lipid bilayer interaction as a function of temperature and can explain the functional breakdown by monomerization while porin secondary structure is still preserved. 相似文献
93.
Helfenstein Fabrice; Berthouly Anne; Tanner Marion; Karadas Filiz; Richner Heinz 《Behavioral ecology》2008,19(1):108-115
Carotenoids are antioxidants playing major roles in physiologicalfunctions at various stages of an animal's life. Female birdsdeposit large amounts of carotenoids into their eggs. Carotenoidsare, however, a limiting resource, and females are expectedto balance carotenoid deposition into the eggs with their utilizationfor themselves. Carotenoid availability is thus likely to determineboth the levels of yolk carotenoids and maternal care duringrearing. Carotenoids have been shown to benefit the embryo andthe growing nestling, and it can be hypothesized that an increasein carotenoid availability during laying leads to higher nestlingcondition and competitive ability. We manipulated carotenoidavailability to great tit pairs prior to and during egg layingand later partially cross-fostered chicks at hatching. Duringthe rearing period, we measured how carotenoid availabilityaffected nestlings begging behavior and male and female feedingeffort. We also manipulated the ectoparasite load, predictingthat carotenoid supplementation would help adults and nestlingto cope with parasites. Nestlings hatched from eggs laid bycarotenoid-supplemented females and raised in small broods beggedmore intensely. Nestlings in small deparasitized broods alsobegged more actively. The feeding effort of control femalesincreased with brood size, whereas the feeding effort of carotenoid-supplementedfemales was high whatever the brood size. Male feeding effortwas unaffected by our treatment. Our results support the hypothesisthat maternally derived carotenoids increase nestling beggingbehavior and hence competitive ability. They further suggestthat carotenoid availability determines the level of parentalinvestment and can mediate trade-offs between life-history traits. 相似文献
94.
Clioquinol inhibits peroxide-mediated toxicity through up-regulation of phosphoinositol-3-kinase and inhibition of p53 activity 总被引:1,自引:0,他引:1
Filiz G Caragounis A Bica L Du T Masters CL Crouch PJ White AR 《The international journal of biochemistry & cell biology》2008,40(5):1030-1042
A growing body of evidence supports a central role for biometals in neurodegenerative disorders. Biometals induce oxidative stress through the generation of reactive oxygen species and contribute to neuronal cell dysfunction in Alzheimer's disease (AD), prion disorders and Parkinson's disease (PD). Therapies based on modulation of biometal metabolism are currently being developed and the metal ligand, 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol or CQ) has been investigated for the treatment of AD. CQ has also shown therapeutic benefits in an animal model of PD. However, little is known about the neuroprotective processes of CQ in vivo. In this study, we examined the effect of CQ in BE(2)-M17 human neuroblastoma cells exposed to increased oxidative stress (hydrogen peroxide (H2O2) treatment). Although CQ alone induced a moderate toxic effect on cells, when added to H2O2-treated M17 cells, CQ induced a significant inhibition of H2O2 toxicity. This correlated with up-regulation of phosphoinositol-3-kinase (PI3K) activity in CQ-treated cells. The protective action of CQ was not observed in murine N2a neuroblastoma cells treated with H2O2 and this cell-line did not reveal CQ-mediated increases in PI3K activation. The protective effect was specific for CQ and was not induced by a number of different metal ligands. Inhibition of PI3K activity with LY294002 prevented CQ protection against H2O2 toxicity, demonstrating a crucial role for CQ activation of PI3K in protection against oxidative stress. Furthermore, CQ inhibited H2O2-mediated up-regulation of p53 activity in the M17 cells and this was dependent on PI3K activation. Our studies demonstrate that in human M17 cells, CQ can protect against oxidative stress by activating the PI3K-dependent survival pathway and blocking p53-mediated cell death. These findings have important implications for the development of protective metal ligand-based therapies for treatment of disorders involving oxidative stress. 相似文献
95.
Ramazan Üstün Elif Kaval Oğuz Çağrı Delilbaşı Ayşe Şeker Filiz Taşpınar Mehmet Reşit Öncü 《Somatosensory & motor research》2017,34(4):248-257
Purpose: Ankaferd Blood Stopper® (ABS), a licenced medicinal herbal extract, is commonly used as an effective topical haemostatic agent. This study is designed to investigate whether topical ABS application may cause peripheral nerve degeneration and neuromuscular dysfunction in a mouse sciatic nerve model.Methods: Twenty mice were randomly divided into two groups; an ABS treated experimental group and a saline-treated control group. Left sciatic nerves were treated with 0.3?ml of ABS in the experimental group and 0.3?ml of sterile saline in the control group for 5?min. Peripheral nerve degeneration and neuromuscular dysfunction were evaluated by behavioural tests, electrophysiological analysis and weight ratio comparison of target muscles.Results: The motor function, assessed by the sciatic function index, was significantly impaired in ABS-treated animals as compared to the animals treated with saline. Motor coordination, evaluated with the rotarod test, was significantly decreased (–42%) in ABS-treated animals compared to the saline-treated animals. The degree of pain, assessed by the reaction latency to thermal stimuli (hot-plate test), was significantly prolonged (313%) in ABS-treated mice when compared to the saline-treated mice. ABS-treated mice showed a significant reduction in motor nerve conduction velocity (MNCV) (–52%) and the compound muscle action potential (CMAP) (–47%); however, it significantly prolonged onset latency (23%). The gastrocnemius muscles weight ratio of the ABS group was considerably lower than that of the control group.Conclusions: These findings demonstrate that ABS triggers peripheral nerve degeneration and functional impairment and, thus promotes a deterioration of sciatic nerves. 相似文献
96.
Effects of aminoguanidine and antioxidant erdosteine on bleomycin-induced lung fibrosis in rats. 总被引:2,自引:0,他引:2
Zeki Yildirim Yusuf Turkoz Mahir Kotuk Ferah Armutcu Ahmet Gurel Mustafa Iraz Suleyman Ozen Ismet Aydogdu Omer Akyol 《Nitric oxide》2004,11(2):156-165
Reactive oxygen and nitrogen species have been implicated in the pathogenesis of bleomycin-induced lung fibrosis. The effects of aminoguanidine and erdosteine on the bleomycin-induced lung fibrosis were evaluated in rats. The animals were placed into five groups: Vehicle + vehicle, vehicle + bleomycin (2.5 U/kg), bleomycin + aminoguanidine (200 mg/kg), bleomycin + erdosteine (10 mg/kg), and bleomycin + erdosteine + aminoguanidine. Bleomycin administration resulted in prominent lung fibrosis as measured by lung hydroxyproline content and lung histology, which is completely prevented by erdosteine and aminoguanidine. A strong staining for nitro tyrosine antibody in lung tissue and increased levels of lung NO were found in bleomycin group, that were significantly reduced by aminoguanidine and erdosteine. Aminoguanidine and erdosteine significantly prevented depletion of superoxide dismutase and glutathione peroxidase and elevated myeloperoxidase activities, malondialdehyde level in lung tissue produced by bleomycin. Data presented here indicate that aminoguanidine and erdosteine prevented bleomycin-induced lung fibrosis and that nitric oxide mediated tyrosine nitration of proteins plays a significant role in the pathogenesis of bleomycin-induced lung fibrosis. Also our data suggest that antifibrotic affect of antioxidants may be due to their inhibitory effect on nitric oxide generation in this model. 相似文献
97.
This study was initiated to evaluate the status of selenium in Turkish residents. Serum selenium level of 76 healthy children, living in Ankara, aged 2 mo-13 y was determined by a spectrofluorometric method. Average selenium level was found to be 88.1 +/- 12.4 micrograms/L (mean +/- SD). Selenium levels showed a tendency to increase with age and mean selenium level in early infancy was lower than that of school children; no relation to the sex and hematological parameters such as hemoglobin concentration and white blood cell counts were observed. 相似文献
98.
Karadas F Wood NA Surai PF Sparks NH 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2005,140(4):506-511
The aim of this study was to evaluate carotenoid and vitamin E distribution in egg and tissues of newly hatched chicks from wild mallard (Anas platyrhynchos), game pheasant (Phasianus colchicus), free-range guinea fowl (Numida meleagris), hen (Gallus domesticus) and domestic duck (Anas platyrhynchos) and intensively housed hens. Carotenoid concentrations in the egg yolk of free-range guinea fowl, pheasant and wild mallard were similar (61.3-79.2 microg/g). Egg yolks from ducks and intensively housed hens were characterised by the lowest carotenoid concentration comprising 11.2-14.8 microg/g. However, carotenoid concentration in eggs from free-range ducks and hens was less than half of that in free-range guinea fowl or pheasant. Depending on carotenoid concentration in the livers of species studied could be placed in the following descending order: free living pheasant>free-range guinea fowl>free-range hen>intensively housed hen>wild mallard>housed duck>free-range duck. The carotenoid concentrations in other tissues of free-range guinea fowl and pheasant were substantially higher than in the other species studied. Egg yolk of housed hens was characterised by the highest alpha- and gamma-tocopherol concentrations. In accordance with the alpha-tocopherol concentration in the egg yolk, the birds can be placed in the following descending order: intensively housed hen>wild mallard>free-living pheasant>free-range duck>free-range hen=free-range guinea fowl>housed duck. The main finding of this work is species- and tissue-specific differences in carotenoid and vitamin E distribution in the various avian species studied. 相似文献
99.
One of the most damaging effects of reactive oxygen species (ROS) is lipid peroxidation, the end-product of which is malondialdehyde (MDA). This study was aimed to evaluate erythrocyte MDA levels during fracture healing in rats. Thirty male rats were used and the rats were divided into two groups to serve as controls and tests. Six rats were used as a control group that was not subject to fracture. The remaining 24 rats were divided into four groups and erythrocyte MDA levels were examined on days 5, 10, 20 and 30 post fracture. The right fibulas of rats were broken by manual angulation in the experimental group. The erythrocyte malondialdehyde level was measured in the experimental and control groups. The difference between malondialdehyde levels of control and experimental groups was statistically significant (p<0.05). Oxidative stress clearly increases during fracture healing in rats. 相似文献
100.
Effect of long-term therapy with sodium valproate on nail and serum trace element status in epileptic children 总被引:2,自引:0,他引:2
Armutcu F Ozerol E Gurel A Kanter M Vural H Yakinci C Akyol O 《Biological trace element research》2004,102(1-3):1-10
Antiepileptic drugs could cause changes in the trace element status of the body. Valproic acid (VPA) is a very effective anticonvulsant
agent widely used in the management of various forms of epilepsy. Nail trace element content is a reliable index of trace
element nutritional status of the body. To determine whether some of the side effects of antiepileptic drugs could be the
result of zinc (Zn) depletion within tissues, Zn concentrations as well as copper (Cu) concentrations in nail and serum in
59 children having various types of epilepsy receiving valproate and 31 controls were assessed. Although serum Zn level in
epileptic patients was found to be decreased, there was no difference in nail samples when compared to controls. There was
a statistically significant increase in nail Cu level in epileptic patients when compared to controls. On the other hand,
serum Cu levels were not different between the groups. Although none of our patients showed any symptoms of Cu elevation and
Zn depletion, we should pay attention to potential body trace element changes in patients with epilepsy under VPA treatment.
In conclusion, our results indicate that serum trace metal homeostasis might be affected by VPA therapy, but not by the convulsive
disorder itself. 相似文献