In this report we present several examples in which nickel(II) in combination with DNA damaging agents caused an enhanced or synergistic biological response using several different endpoints. These examples of Ni(II) toxicity represent several approaches designed to understand the genotoxicity of Ni(II) as well as several other metal ions. They are discussed in this report as a partial basis for our hypothesis that Ni(II) may alter the cellular processing of DNA damage at some common point in the pathway for DNA repair of several different agents. In cultured Chinese hamster cells DNA damage by Ni(II) ions was not readily demonstrated by the method of alkaline elution, but pretreatment of cells with Ni(II) before X‐irradiation produced an enhanced amount of strand breaks compared to the amount produced by X‐rays alone. A synergistic enhancement of cell transformation of Syrian hamster embryo cells was observed for combined treatments of Ni(II) and benzo(a)pyrene. The nickel enhancement of mutagenesis by ultraviolet light was demonstrated for the bacterial gene gpt stably integrated into the Chinese hamster V79 genome. 相似文献
Abstract This study demonstrates that the growth of S. typhimurium in Luria Bertani broth supplemented with acetate, propionate, butyrate, or a mixture of the three SCFA, affected cell‐association and the ability to invade cultured HEp‐2 cells. Cell‐association and invasion was determined after growth for 4 h of growth in the presence of the SCFA at pH 6 and 7. The results suggest that the growth rate of the culture may have affected cell‐association and invasion since accompanying the significant decrease in growth rate in the presence of SCFA at pH 6 was a decrease in cell‐association and invasion. However, the results also suggest that the individual SCFA may play a role in modulating cell‐association and the invasion phenotype and the regulation of cell‐association and invasion by the SCFA was dependent on the concentration and the pH of the medium. Although the growth rates were similar for S. typhimurium in the SCFA mixture, butyrate (100 mM) and propionate (50 mM) at pH 6, differences in cell‐association and invasion were observed among these cultures. Also, at pH 7, differences were observed among the SCFA treatments even though the growth rates were similar. 相似文献
Abstract In this work, gas flow and heat transfer have been numerically investigated and analyzed for both cathode/anode ducts of proton exchange membrane (PEM) fuel cells. The simulation is conducted by solving a set of conservation equations for the whole domain consisting of a porous medium, solid structure, and flow duct. A generalized extended Darcy model is employed to investigate the flow inside the porous layer. This model accounts for the boundary-layer development, shear stress, and microscopic inertial force as well. Effects of inertial coefficient, together with permeability, effective thermal conductivity, and thickness of the porous layer on gas flow and heat transfer are investigated. 相似文献
The molecular mechanisms underlying proliferation and apoptosis induced by p-nonylphenol (NP) through regulation of mRNA and protein expression of c-myc, p53 mRNA and the protein was investigated using ovarian cancer PEO4 cells. PEO4 cells were grown in the Dulbecco's modified Eagle medium (DMEM), 3(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay was employed to investigate cell proliferation. RT-PCR and immunohistochemistry was performed to determine mRNA and protein expression of PEO4 c-myc and p53. Within the range of approximately 8–9×10?7 mol L?1, NP stimulated proliferation in PEO4 cells in a concentration-and time-dependent manner. RT-PCR and immunohistochemistry analyses revealed that treatment with 32 × 10?7 mol L?1 NP for 72 hr resulted in increased mRNA and protein expression of PEO4 c-myc and p53. Evidence indicates that NP exerted estrogenic actions and stimulated proliferation in estrogen responsive ovarian cancer PEO4 cells by up-regulation of c-myc mRNA and protein expression. 相似文献
The alteration of physico-chemical properties of sediment organic matter (SOM) incubated under current-harvesting conditions as well as no-current producing conditions over 120 days using sediment microbial fuel cell systems was examined. The SOM was microbially oxidized under anaerobic conditions with an electrode serving as a terminal electron acceptor. It was found that SOM around the electrochemically-active electrodes became more humified, aromatic, and polydispersed, and had a higher average molecular weight, along with its partial degradation and electricity generation compared to that for the original sediment. These changes in SOM properties were analogous to those commonly observed in the early stages of the SOM diagenetic process (i.e. humification). Such a humification-like process was evidently more stimulated when electrical current was produced than no-current condition. These new findings associated with microbially-catalyzed electricity generation may present a potential for the energy-efficient remediation, monitoring, and/or management of the geo-environment. 相似文献
A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures is described. The technique is based upon several key steps including: (1) reduced colcemid concentration, (2) reduced exposure to trypsin-EDTA, and (3) maintaining cells in single suspension by adjusting cell concentration appropriately. Chromosomes with banding resolution up ot 800 bands per haploid set can be routinely produced. The described methodology is particularly useful in defining and establishing the clinical significance of subtle structural aberrations. 相似文献
This study for the first time proposed an efficient microbial electrolyte/UV system for Methyl Orange decomposition. With an external applied voltage of 0.2 V and cathode aeration of20 mL/min, H_2O_2 could be in-situ generated from two-electron reduction of oxygen in cathode, reaching to 8.1 mg/L in 2 hr and continued to increase. The pollutant removal efficiency of approximate 94.7% was achieved at initial neutral pH, with the activation of ·OH in the presence of UV illumination. Although the nature of its guiding principles remain on the vista of practical exploration, this proof-of-concept study provides an alternative operation pattern of solar–microbial hybrid technology for future wastewater treatment from a basic but multidisciplinary view. 相似文献
Inhaled airborne particulate matter (PM) represents a potentially significant health hazard to humans. Exposure to PM strongly correlates with pulmonary inflammation and incidences of severe respiratory distress, including increased hospital admissions for breathing disorders, asthma, emphysema, and chronic bronchitis. PM generated from the combustion of fuel oils and coals contain a number of water-soluble transition metals including Fe, V, and Zn.
We have evaluated the impact of PM types with varying composition collected from the combustion of oils and coals on the health and metabolism of lung cell cultures. Three colorimetric assays (sulforhodamine B (SRB), Janus green, and MTT) have been adapted to quantify the impact of PM on rat lung alveolar type II epithelial cells (RLE-6TN cells). The PM toxicity metrics evaluated were inhibition of cell proliferation (SRB and Janus green) and inhibition of cellular metabolism (MTT). Cell proliferation is inhibited in a consistent dose-dependent manner by PM concentrations from 25 to 250 μg/ml. At a level of 100 μg/ml, oil-derived PM diminishes cell metabolism by as much as 40% relative to controls; the degree of inhibition is strongly dependent on PM particle size and metal content. Conversely, coal-derived PM at the same dosage diminishes cell metabolism by no more than 20% relative to controls. All three assays provide highly repeatable results and consistent toxicity rankings of the PMs evaluated. Overall, metabolic inhibition as measured by the MTT assay was deemed the most appropriate metric for PM toxicity, primarily due to its applicability with in vivo-like confluent cell monolayers. 相似文献