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1.
Objectives: To understand if there exists a functional interaction between arsenic trioxide and paclitaxel in vitro.
Materials and methods: HeLa and HCT116 ( ρ 53+/+ and ρ 53−/− ) cells were treated with As2O3 and/or paclitaxel for various times. Treated cells were collected for analyses using a combination of flow cytometry, fluorescence microscopy and Western blotting.
Results: Because As2 O3 is capable of inhibiting tubulin polymerization and inducing mitotic arrest, we examined whether there existed any functional interaction between As2 O3 and paclitaxel, a well-known microtubule poison. Flow cytometry and fluorescence microscopy revealed that although As2 O3 alone caused a moderate level of mitotic arrest, it greatly attenuated paclitaxel-induced mitotic arrest in cells with p53 deficiency. Western blot analysis showed that As2 O3 significantly blocked phosphorylation of BubR1, Cdc20, and Cdc27 in cells treated with paclitaxel, suggesting that arsenic compromised the activation of the spindle checkpoint. Our further studies revealed that the attenuation of paclitaxel-induced mitotic arrest by As2 O3 resulted primarily from sluggish cell cycle progression at S phase but not enhanced mitotic exit.
Conclusion: The observations that As2 O3 has a negative impact on the cell cycle checkpoint activation by taxol should have significant clinical implications because the efficacy of taxol in the clinics is associated with its ability to induce mitotic arrest and subsequent mitotic catastrophe. 相似文献
Materials and methods: HeLa and HCT116 ( ρ 53
Results: Because As
Conclusion: The observations that As
2.
Abstract. This study investigated the effect of acquired resistance in guinea-pigs on the metabolic rate of adult females of the tick Rhipicephalus evertsi evertsi. Guinea-pigs were subjected to three successive infestations of ticks and the rate of CO2 production (Vco2 ) measured in first and third infestation engorged females. Ticks which fed on resistant hosts showed a 52% decrease in mass compared to ticks that fed on naive animals. Reduction in mass was accompanied by a decrease in Vco2 (mlh-1 ) per tick but an increase in mass specific Vco2 (mlg_1 h_1 ). However, both groups shared a single allometric relationship between body mass and metabolic rate (Vco2 ). We suggest that the differences in size rather than any factor directly relating to the mechanism of acquired resistance account for the differences in metabolic rate between ticks fed on naive and resistant guinea-pigs. 相似文献
3.
The production of H2 O2 by cucumber hypocotyl segments ( Cucumis sativus L. cv. Wisconsin SMR 58) in response to α-1,4-linked oligomers of galacturonic acid and oligo-β-glucans from the cell walls of Phytophthora megasperma f. sp. glycinea was studied. Oligogalacturonides with degrees of polymerization of 9 to 13 elicited H2 O2 production, the most effective being the deca-, undeca- and dodecamers. A similar relationship between size and effect was previously obtained when oligogalacturonides were tested for their ability to elicit lignification in cucumber hypocotyls. The oligogalacturonide-induced increase in H2 O2 concentration was detected after 4 h, reaching a maximum after 10 h of incubation. The glucan elicitor induced lignification at a 100-fold lower concentration than the oligogalacturonides, but yielded only 10% of the maximum H2 O2 accumulation seen with oligogalacturonides. The glucan elicitor-induced H2 O2 production was detectable after 2 h, and reached a maximum after 4 to 6 h. Catalase abolished the elicitation of both phenol red oxidation and lignification in cucumber hypocotyls. At least part of the oligogalacturonide-induced H2 O2 production appeared to be dependent upon de novo protein synthesis. 相似文献
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Abstract Bacteroides fragilis Bf-2 cells were more sensitive to far-UV radiation, N -methyl- N '-nitrosoguanidine, ethylmethane sulphonate, acriflavine and mitomycin C under aerobic conditions than under anaerobic conditions. The opposite effect was observed with H2 O2 -treated cells and exposure to O2 enhanced the survival of H2 O2 -treated cells. Pretreatment of cells with sublethal concentrations of H2 O2 also increased the survival of H2 O2 -treated cells. Reactivation of UV- and X-irradiated and methylmethane sulphonate and H2 O2 -treated phage b-1 was induced by O2 and H2 O2 in B. fragilis . 相似文献
6.
The effect of hydrogen peroxide on Salmonella typhimurium in whole egg was evaluated. The bactericidal effects observed on the test organism at 5° and 20°C were found to be similar. There was a 99% kill in the presence of 0°5% and 1°0% H2 O2 . Addition of the test organism and H2 O2 after pre-heating the egg material at 40°C for 15 min caused a rapid kill which was 10000-fold greater than that produced by H2 O2 alone. 相似文献
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8.
Comparison of quantitative and qualitative methods of detecting hydrogen peroxide produced by human vaginal strains of lactobacilli 总被引:1,自引:0,他引:1
A quantitative method was developed for the measurement of micromolar quantities of H2 O2 produced in Rogosa broth and peptonized milk broth by vaginal strains of lactobacilli isolated from women. The production of substantial amounts reproducibly was dependent on the growth of the organisms in acid media (pH ≤6.0) under anaerobic or micro-aerophilic conditions with continuous agitation. The addition to the media of the enzyme inhibitor, 3-amino-l,2,4-triazole, with or without catalase sometimes induced the production of H2 O2 especially in non-agitated cultures. However, other agents such as concanavalin and o -dianisidine had no enhancing effect, and catalase or peroxidase alone completely inhibited H2 O2 production.
The H2 O2 produced in the acid media was stable for more than a month at 5°C but not in media at pH ≥ 7.0. Of five strains of lactobacilli tested by the quantitative method and by a chromogenic qualitative method (Rogosa-catalase or -peroxidase agar), three consistently produced H2 O2 measurable by the former method, but none did so after growth of the organisms on Rogosa-catalase/peroxidase agar which suggested that the qualitative method was unreliable. The fact that H2 O2 was produced in substantial quantities by some strains and not at all by others enabled H2 O2 -producers and non-producers to be distinguished easily. 相似文献
The H
9.
Leishmania donovani , the causative agent of visceral leishmaniasis, uses a cascade of enzymes that include cytosolic tryparedoxin peroxidase (cTXNPx) for detoxification of peroxides, an event pivotal for survival of digenic parasites living in two disparate biological environments. In this study, we observed an increase in promastigote cTXNPx levels after exposure to H2 O2 and this group did not show any cell death; however, exposure to a combination of H2 O2 and nitric oxide resulted in significant reduction of cTXNPx levels accompanied by high cell death. The protective relationship between higher levels of cTXNPx and survival was further substantiated by the improved ability of L. donovani promastigotes overexpressing cTXNPx to withstand exposure to H2 O2 and nitric oxide combination as compared with vector transfectants. In addition, cTXNPx transfectants demonstrated increased virulence, causing higher parasite burden in macrophages as compared with vector transfectants. Interestingly, the cTXNPx transfectants as promastigotes or amastigotes were resistant to clearance by the anti-leishmanial drug antimony, suggesting a cTXNPx link to drug response. Mechanistically, cTXNPx overexpression was protective against changes in Ca2+ homeostasis but not against mitochondrial hyperpolarization brought about by exposure to H2 O2 and nitric oxide. Therefore, this study provides a link between cTXNPx expression to survival, virulence and drug response in L. donovani . 相似文献
10.
Effect of broad-band ultraviolet and visible radiation on hydrogen peroxide formation by cultured rose cells 总被引:1,自引:0,他引:1
Terence M. Murphy 《Physiologia plantarum》1990,80(1):63-68
Broad-band radiation from a high-pressure Hg-vapor lamp, including ultraviolet wavelengths from 290 to 400 nm, blue, green and red wavelengths, did not induce the synthesis of H2 O2 in cultured rose cells. This was in contrast to the effects of shortwave (254 nm) ultraviolet radiation, even though, like shortwave ultraviolet radiation, the UV-B component of the broadband radiation induced a striking K+ efflux from the cells, and this efflux has been associated with H2 O2 synthesis in a previous report. The UV-A and visible wavelengths were shown to inhibit the synthesis of H2 O2 . This effect was associated with inhibition of peroxidase, an enzyme reported to be involved in the synthesis of H2 O2 in cell walls. UV-B radiation inhibited the alternate pathway for mitochondrial electron transport, but there was no evidence that this effect contributed to the inhibition of H2 O2 synthesis in cells treated with broad-band radiation. 相似文献
11.
Heide J.K. Slade J.Petra Schumann David T. Jones David R. Woods 《FEMS microbiology letters》1983,20(3):401-405
Abstract Reactivation of UV-irradiated phage b-1 was induced by H2 O2 and UV in Bacteroides fragilis . The characteristics of H2 O2 and UV induced phage reactivation differ from a previously reported oxygen induced reactivation system. The survival of B. fragilis cells after UV irradiation was also increased by pretreatment with H2 O2 . DNA synthesis was not inhibited in the host cells exposed to H2 O2 concentrations which induced phage reactivation. The pattern of DNA degradation and synthesis after UV irradiation with and without H2 O2 differed from the effect of O2 on DNA synthesis in irradiated B. fragilis cells. 相似文献
12.
The hydrogen peroxide (H2 O2 ) stress response in Enterococcus faecalis ATCC19433 was investigated. A 2·4 mmol l−1 H2 O2 pretreatment conferred protection against a lethal concentration (45 mmol l−1 ) of this agent. The relatively high concentrations of H2 O2 used for adaptation and challenge treatments in Ent. faecalis emphasised the strong resistance towards oxidative stress in this species. Various stresses (NaCl, heat, ethanol, acidity and alkalinity) induced weak or strong H2 O2 cross-protection. This paper describes the involvement of protein synthesis in the active response to lethal dose of H2 O2 , in addition to the impressive enhancement of synthesis of five H2 O2 stress proteins. Combined results suggest that these proteins might play an important role in the H2 O2 tolerance response. 相似文献
13.
Suspension-cultured rose ( Rosa damascena Mill. cv. Gloire de Guilan) cells irradiated with UV-C (254 nm. 558 J m−2 ) showed a transient production of H2 O2 as measured by chemiluminescence of luminol in the presence of peroxidase (EC 1.1 1.1.7). The peak concentration of H2 O2 , which occurred at about 60–90 min after irradiation, was 8–9 μ M . The time course for the appearance of H2 O2 matched that for UV–induced K+ efflux. Treatments that inhibited the UV-induced efflux of K+ , including heat and overnight incubation with cycloheximide and diethylmaleate, also inhibited the appearance of H2 O2 . The converse was not always true, since catalase (EC 1.11.1.6. and salicylhydroxamic acid, which inhibited luminescence, did not stop K+ efflux. We conclude that H2 O2 synthesis depends on K+ efflux. Because H2 .O2 in the extracellular space is required for lignin synthesis in many plant tissues, we suggest that the UV–stimulated production of H2 O2 is an integral part of a defensive lignin synthesis. 相似文献
14.
Valentino Casolo Enrico Braidot Elisa Chiandussi Angelo Vianello Francesco Macrì 《Physiologia plantarum》2003,118(3):313-318
The role of a recently identified K+ ATP channel in preventing H2 O2 formation was examined in isolated pea stem mitochondria. The succinate-dependent H2 O2 formation was progressively inhibited, when mitochondria were resuspended in media containing increasing concentration of KCl (from 0.05 to 0.15 M ). This inhibition was linked to a partial dissipation of the transmembrane electrical potential (ΔΨ) induced by KCl. Conversely, the malate plus glutamate-dependent H2 O2 formation was not influenced. The succinate-sustained H2 O2 generation was also unaffected by nigericin (a H+ /K+ exchanger), but completely prevented by valinomycin (a K+ ionophore). In addition, cyclosporin A (a K+ ATP channel opener) inhibited this H2 O2 formation, while ATP (an inhibitor of the channel opening) slightly increased it. The inhibitory effect of ATP was strongly stimulated in the presence of atractylate (an inhibitor of the adenine nucleotide translocase), thus suggesting that the receptor for ATP on the K+ channel faces the intermembrane space. Finally, the succinate-dependent H2 O2 formation was partially prevented by phenylarsine oxide (a thiol oxidant). 相似文献
15.
J. M. Rodríguez M. I. Martínez A. M. Suárez J. M. Martínez & P. E. Hernández 《Letters in applied microbiology》1997,25(1):73-74
The effect of MRS broth on the stability of hydrogen peroxide (H2 O2 ) has been studied. Known concentrations (1–100 μg ml−1 ) of H2 O2 were prepared in distilled water, phosphate buffer (pH 7·0) and MRS broth (pH 6·2 and 3·9). H2 O2 was very stable in aqueous and buffer solutions but it was rapidly degraded in MRS broth (pH 3·9). The presence of H2 O2 in MRS broth (pH 6·2) could not be detected. 相似文献
16.
Is hydrogen peroxide a second messenger of salicylic acid in systemic acquired resistance? 总被引:18,自引:1,他引:17
Urs Neuenschwander Bernard Vernooij Leslie Friedrich Scott Uknes Helmut Kessmann John Ryals 《The Plant journal : for cell and molecular biology》1995,8(2):227-233
Elevated levels of salicylic acid (SA) are required for the induction of systemic acquired resistance (SAR) in plants. Recently, a salicylic acid-binding protein (SABP) isolated from tobacco was shown to have catalase activity. Based on this finding elevated levels of hydrogen peroxide (H2 O2 ) were postulated to act as a second messenger of SA in the SAR signal transduction pathway. A series of experiments have been carried out to clarify the role of H2 O2 in SAR-signaling. No increase of H2 O2 was found during the onset of SAR. Induction of the SAR gene, PR-1, by H2 O2 and H2 O2 -inducing chemicals is strongly suppressed in transgenic tobacco plants that express the bacterial salicylate hydroxylase gene, indicating that H2 O2 induction of SAR genes is dependent on SA accumulation. Following treatment of plants with increasing concentrations of H2 O2 , a dose-dependent accumulation of total SA species was found, suggesting that H2 O2 may induce PR-1 gene expression through SA accumulation. While the results do not support a role for H2 O2 in SAR signaling, it is suggested that SA inhibition of catalase activity may be important in tissues undergoing a hypersensitive response. 相似文献
17.
The effects of physical and chemical factors on the production of H2 O2 from Escherichia coli cells were studied. When 20 mmol 1-1 Tris-HCl buffer was used for this purpose the electron transport system (ETS) showed the highest activity at pH 7.6-8.2. KCN promoted the production of H2 O2 from E. coli cells, and the optimum concentration was changed in different reaction times and pH values. Glucose, 5 mg ml-1 , increased the ETS activity about twofold. The other substrates and surfactants did not increase the chemiluminescence intensity. NaNO2 and Na2 SO4 in inorganic salts significantly reduced the ETS activity above 70%. In addition, the optimum temperature for the production of H2 O2 was 30°C in this study. When glucose (5 mg ml-1 ) and KCN (0.2 mmol 1-1 ) were added to the reaction buffer containing 0.5 mmol 1-1 menadione, the detectable minimum cell densities (averages of triplicate assay) of E. coli, Enterobacter cloacae and Serratia marcescens were 5 times 103 cells ml-1 , 104 cells ml-1 and 104 cells ml-1 respectively. 相似文献
18.
Twelve strains of meat lactic starter cultures (Pediococcus spp. and Lactobacillus plantarum) were found to produce hydrogen peroxide in vitro. The (cumulative) amounts of H2 O2 produced were measured through the peroxidative action of catalase on H2 O2 and oxidation of added formate to CO2 by the H2 O2 -catalase complex formed. There was a problem in building a calibration curve for converting values of formate oxidation into amounts of H2 O2 , either by adding H2 O2 directly to the assay mixture or having it produced via a glucose-glucose oxidase system. 相似文献
19.
Terry L. Highley 《FEMS microbiology letters》1987,48(3):373-377
Abstract Hydrogen peroxide (H2 O2 ) has been implicated in degradation of wood by both brown-rot and white-rot fungi. This study found that low concentrations of nitrogem and carbohydrates (cellobiose, glucose, xylose and mannose) in an agar medium had little effect on H2 O2 production by white-rot fungi. However, low concentrations of nitrogen and carbohydrates stimulated H2 O2 production by brown-rot fungi. Use of the chromogen 2,2'-azino-di(3-ethyl benzthiazoline-6-sulphonic acid) (ABTS) with horseradish peroxidase to detect H2 O2 by the fungi was slightly better than detection by the chromogen o -dianisidine with horseradish peroxidase. An auxiliary test to check the role of H2 O2 in wood decay found that hydrogen peroxide-negative isolates of the white-rot fungi Pharnerochaete chrysosporium and Ganoderma applanatum were unable to decay sweetgum and southern pine. 相似文献
20.
Abstract: We studied the action of H2 O2 on the exocytosis of glutamate by cerebrocortical synaptosomes. The treatment of synaptosomes with H2 O2 (50–150 µ M ) for a few minutes results in a long-lasting depression of the Ca2+ -dependent exocytosis of glutamate, induced by KCl or by the K+ -channel inhibitor 4-aminopyridine. The energy state of synaptosomes, as judged by the level of phosphocreatine and the ATP/ADP ratio, was not affected by H2 O2 , although a transient decrease was observed after the treatment. H2 O2 did not promote peroxidation, as judged by the formation of malondialdehyde. In indo-1-loaded synaptosomes, the treatment with H2 O2 did not modify significantly the KCl-induced increase of [Ca2+ ]i . H2 O2 inhibited exocytosis also when the latter was induced by increasing [Ca2+ ]i with the Ca2+ ionophore ionomycin. The effects of H2 O2 were unchanged in the presence of superoxide dismutase and the presence of the Fe3+ chelator deferoxamine. These results appear to indicate that H2 O2 , apparently without damaging the synaptosomes, induces a long-lasting inhibition of the exocytosis of glutamate by acting directly on the exocytotic process. 相似文献