纳米氧化锌(Zn O NPs)对呼吸道的毒性损伤作用备受关注,但有关其对呼吸道上皮细胞动态变化的影响机理还有待深入研究.因此,本研究通过将大鼠气管上皮细胞(RTE)暴露于不同浓度(1和10 mg·L~(-1))和不同粒径(50和200 nm)的Zn O NPs中,利用细胞电阻抗检测技术(ECIS)检测细胞动态变化,采用CCK8法检测细胞生长抑制效应,并通过胞内ROS和MDA含量变化探讨其影响机制.ECIS检测结果显示,Zn O NPs暴露下,RTE细胞生长和增殖受到明显抑制,且具有浓度依赖效应.当暴露浓度为1 mg·L~(-1)时,与对照组相比,50 nm暴露组细胞电阻抗值的下调幅度为18%,为200 nm暴露组的1.2倍.Zn O NPs诱导的RTE细胞增殖抑制率具有浓度依赖效应,当暴露浓度为10 mg·L~(-1)时,50和200 nm暴露组细胞增殖抑制率分别为暴露浓度为1 mg·L~(-1)时的2.9和1.4倍.Zn O NPs诱导的RTE细胞氧化应激结果显示,胞内ROS和MDA含量随着纳米颗粒暴露浓度的增加而增加,随着纳米颗粒粒径的减小而增加,具有显著的浓度-和剂量-依赖效应.当Zn O NPs浓度分别为1和10 mg·L~(-1)时,ROS含量分别是对照组的2.8和3.7倍;当暴露浓度为10 mg·L~(-1)时,50 nm暴露组细胞内ROS含量是200 nm暴露组的1.7倍;暴露浓度为1和10 mg·L~(-1)时,50 nm氧化锌处理组诱导的细胞内MDA含量分别是对照组的5.4和7.9倍.Zn O NPs能够影响呼吸道上皮细胞动态变化,从而破环RTE细胞屏障并进入细胞,诱导胞内ROS和MDA水平升高,进而抑制细胞的生长与增殖.研究表明,影响Zn O NPs诱导的RTE细胞动态变化和氧化应激的关键因素是颗粒粒径与暴露浓度. 相似文献
A strategy for management of giant sequoia groves is formulated using a conceptual framework for ecosystem management recently
developed by Region Five of the USDA Forest Service. The framework includes physical, biological, and social dimensions. Environmental
indicators and reference variability for key ecosystem elements are discussed in this paper. The selected ecosystem elements
include: 1) attitudes, beliefs, and values; 2) economics and subsistence; 3) stream channel morphology; 4) sediment; 5) water;
6) fire; 7) organic debris; and 8) vegetation mosaic. Recommendations are made for the attributes of environmental indicators
that characterize these elements. These elements and associated indicators will define and control management activities for
the protection, preservation, and restoration of national forest giant sequoia ecosystems. 相似文献
African savanna elephants, Loxodonta africana, live in stable family groups consisting of adult females and their dependent offspring. During the dry season, clans consisting of several family groups typically share a common home range. We compared spatial relationships and mitochondrial DNA (mtDNA) haplotypes among 14 adult female elephants within 3 clans during the dry season in northern Zimbabwe. Spatial relationships were studied by radio-tracking. Home-range similarity was quantified by correlating the estimated utilization distributions of all pairs of elephants. Clans were identified by cluster analysis of the home-range similarity values. All three clans contained at least two of the five mtDNA haplotypes that were found, indicating that clan members are not necessarily matrilineally related. Within clans, home ranges of elephants with the same haplotype were not significantly more similar to each other than those of elephants with different haplotypes. Most elephants within each clan used their shared home ranges independently of each other: the distribution of distances between their positions at any given time did not differ from the distribution expected by chance. However, 8 out of the 26 within-clan pairs exhibited long-term coordination of space use by remaining within known hearing distance of each others low-frequency calls significantly more often than expected by chance. At least four of these coordinated pairs consisted of animals in different family groups. Elephants in three of the four different-family pairs whose movements were coordinated had different haplotypes. Further research is needed to determine the relationship between these coordinated movements and conventionally defined bond-group behavior.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by C. Nunn 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
Some lessons for the introduction of hydrogen fueled vehicles can be learned from experience gained by the introduction of
natural gas fueled vehicles, either in Europe or in Argentina. While the European efforts have failed, at least until today,
Argentina has achieved a remarkable market share of about 20% natural gas vehicles since the early 80ies. Beyond a short review
on the constituents of a hydrogen refueling infrastructure, the Compressed Natural Gas (CNG)-example is analyzed to formulate
some ‘must be’s’ for the successful introduction of hydrogen refueling infrastructure: Clear concerted signals have to be
sent by all important players, the politicians as well as the involved industry from car producers to fuel suppliers. Bi-fueled
hybrid vehicles are not seen as a proper tool, as they are forcing neither the user to look for hydrogen nor the supplier
to provide hydrogen. After general considerations, various strategies and policies of different countries and manufacturers
are reviewed. For instance, the electric hybrid cars as already today introduced by some Japanese manufacturers offer the
chance of settling a maintenance infrastructure for electric drive systems already today which can be easily extended to cover
full fuel cell drive systems, once they are available. 相似文献