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排序方式: 共有72条查询结果,搜索用时 11 毫秒
51.
Atanasiu Roxana L. Stea Dino Mateescu Mircea A. Vergely Catherine Dalloz Florence Briot François Maupoil Véronique Nadeau Réginald Rochette Luc 《Molecular and cellular biochemistry》1998,189(1-2):127-135
The chain-breaking antioxidant potential of caeruloplasmin and bovine serum albumin (BSA) has been investigated in comparison with other well-established antioxidants. Their Oxygen Radical Absorbing Capacity (ORAC), was measured by using -phycocyanin (-PC) as a fluorescent indicator protein, 2,2-azobis (2-amidinopropane) hydrochloride (AAPH) as a peroxyl radical generator and the water soluble vitamin E analogue, Trolox, as a reference standard. The relative peroxyl absorbing capacities/mole for Trolox, caeruloplasmin, heat-denatured caeruloplasmin (hCP), catalase, bovine serum albumin (BSA), superoxide dismutase (SOD), and deferoxamine were 1; 2.6; 3.3; 3.7; 1.2; 0.1; 0.2, respectively. Caeruloplasmin was far more effective as a peroxyl radical scavenger than SOD, deferoxamine and BSA, but slightly less effective than catalase. The peroxyl radical absorbing capacity of caeruloplasmin was enhanced by heat-denaturation of the protein. Electron paramagnetic resonance (EPR) spectroscopy using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin-trap, was applied in order to measure the scavenger abilities of caeruloplasmin on superoxide radical and hydroxyl radical production and the concentration required to inhibit by 50% oxygen free radical formation (IC50) was determined. The IC50 values of caeruloplasmin, hCP, and BSA for the superoxide radical were 12, 2, 260 M and for the hydroxyl radical 15, 2, 200 M. These results show that caeruloplasmin is an effective chain-breaking antioxidant for a variety of radicals, independently of its catalytic ferroxidase activity. 相似文献
52.
China’s rich floral diversity includes more than 33 000 vascular plant species,representing approximately 10 percent of all known plant species.Over half of these species are endemic to China.However,China’s rapid economic development in the last 30 years and continuous population growth have seriously damaged plant resources in the wild and the ecological environment,resulting in a dramatic increase in the number of endangered species.There are nearly 4 000 to 5 000 higher plants that are now threatened or on the verge of extinction.To help halt the loss of Chinese plant diversity,Botanic Gardens Conservation International(BGCI) has developed a China programme and opened its first office based in Guangzhou in 2008.This office works along with Chinese partners aiming to secure Chinese plant diversity through integrated conservation approaches with reintroduction/population reinforcement,engagement of local communities in conservation activities,capacity building in horticulture and environmental education and public outreach. 相似文献
53.
Sulfinpyrazone, a potent uricosuric drug, was tested in vitro for its scavenging action against oxygen free radicals. In this study, sulfinpyrazone was able to scavenge 1,1-diphenyl-2-picrylhydrazyl radical with IC 50 value of 29.82 μg/ml compared to butylated hydroxytoluene (BHT, IC 50 value=20.15 μg/ml) and Trolox (IC 50 value=16.01 μg/ml). It was able to scavenge superoxide anion with IC 50 value of 27.72 μg/ml compared to Trolox (IC 50 value=22.08 μg/ml) and ascorbic acid (IC 50 value=14.65 μg/ml). The hydroxyl radical scavenging activity of sulfinpyrazone is in a concentration-dependent fashion. In the range of concentrations used, sulfinpyrazone was not a scavenger toward H 2 O 2 . However, the intracellular H 2 O 2 -induced 2',7'-dichlorofluorescin diacetate (DCF-DA) fluorescence in HL-60 cells was significantly reduced by sulfinpyrazone during 30-60 min of incubation. Finally, phorbol-12-myristate-13-acetate induced-lucigenin chemiluminescence in whole blood was markedly inhibited by sulfinpyrazone. Our results suggest a new direction for the pharmacological actions of sulfinpyrazone in free radical scavenging properties. 相似文献
54.
三江平原沼泽湿地生态承载能力综合评价 总被引:4,自引:0,他引:4
从湿地水资源、土地资源、水环境、生物资源等多方面入手,研究湿地生态系统的承载能力,采用分级评价方法,建立分级评价指标和承载模式,评价了沼泽湿地生态系统的生态弹性度、资源与环境承载力和承载压力度。利用基于加速遗传算法的层次分析技术确定承载模型的权重,计算得出的排序权值具有结果稳定、计算精度高的特点。应用到三江平原沼泽湿地生态承载力的综合评价中,结果表明整个三江平原大部分生态系统处于中稳、较高承载、中低压区。这说明三江平原生态承载能力比较高,人口压力不大,但要进一步提高生态承载能力,则需改善沼泽湿地生态环境,提高水资源利用效率。 相似文献
55.
Protected areas, a corestone of biodiversity conservation, provide a vast array of ecosystem services to support livelihoods of people. However, protected areas, especially freshwater, are under threat with overexploitation of resources changing the land covers and degrading their capacity to supply services. Information on land cover changes and its implications on ecosystems, its services and people, especially in developing countries at a local scale, is largely absent. This study, therefore, seeks to understand people's dependency on ecosystem services and implications of land cover change on ecosystem services and people, with a case study in the Koshi Tappu Wildlife Reserve of Nepal. Using both qualitative and quantitative methods, our findings show high dependency of the locals on a vast array of ecosystem services provided by the reserve. More than half of the sampled households were found to directly derive income from ecosystem services of the reserve. However, land cover changes especially declines in forest (16%), swamps/marshes (4%), rivers (14%) and other ecosystems over a period of 34-years impacted the provision of ecosystem services and people’s dependency notably. The services from forests declined by about 94%, swamps services by 36% and services from river by 57% which were reported to be the high service suppliers. People's dependency, as perceived by the locals, was reduced by 67% over the last ten years. The study highlighting the supply, demand and implications on ecosystem services and people helped to better understand the complex interaction between humans and ecosystems. These results can be used to develop holistic approaches to restore, conserve and manage the ecosystems, and its services by balancing equal supply and demand of ecosystem services required for a self-sustaining human-environment system. It can also contribute to development of important environmental policies and programs in the area. 相似文献
56.
冷驯化对中缅树鼩能量代谢的影响 总被引:1,自引:3,他引:1
在5 ±1 ℃条件下对中缅树鼠句进行冷驯化处理, 测定其能量代谢。冷驯化28 d 后, 体重比对照组显著增加7.33 %; 整体能值达到30.47 ±0.46 kJ / g (N = 8) , 比对照组增加4.98 %; 摄入能比对照组增加36.17 %; 同化能比对照组增加66.2 %; 生长能达到6.98 ±0.53 kJ / 100 g (N = 7) 体重·天, 是对照组的4.85 倍; 维持能比对照组增加64.0 % , 达到352.96 ±28.34 kJ / 100 g 体重·天(N = 7) 。以上结果表明中缅树鼠句在冷胁迫影响下, 以增加能量摄入、能量储存和维持能和降低排泄能量的生理机制来维持能量代谢平衡, 以此对策来提高低温环境适应能力。
相似文献
相似文献
57.
China's rich floral diversity includes more than 33 000 vascular plant species, representing approximately 10 percent of all known plant species. Over half of these species are endemic to China. However, China's rapid economic development in the last 30 years and continuous population growth have seriously damaged plant resources in the wild and the ecological environment, resulting in a dramatic increase in the number of endangered species. There are nearly 4 000 to 5 000 higher plants that are now threatened or on the verge of extinction. To help halt the loss of Chinese plant diversity, Botanic Gardens Conservation International (BGCI) has developed a China programme and opened its first office based in Guangzhou in 2008. This office works along with Chinese partners aiming to secure Chinese plant diversity through integrated conservation approaches with reintroduction/population reinforcement, engagement of local communities in conservation activities, capacity building in horticulture and environmen tal education and public outreach. 相似文献
58.
The multi-tier implementation has become the industry standard for developing scalable client-server enterprise applications.
Since these applications are performance sensitive, effective models for dynamic resource provisioning and for delivering
quality of service to these applications become critical. Workloads in such environments are characterized by client sessions
of interdependent requests with changing transaction mix and load over time, making model adaptivity to the observed workload
changes a critical requirement for model effectiveness. In this work, we apply a regression-based approximation of the CPU demand of client transactions on a given hardware. Then, we use this approximation in an analytic
model of a simple network of queues, each queue representing a tier, and show the approximation’s effectiveness for modeling
diverse workloads with a changing transaction mix over time. Using two case studies, we investigate factors that impact the
efficiency and accuracy of the proposed performance prediction models. Experimental results show that this regression-based approach provides a simple and powerful solution for efficient capacity planning and resource provisioning of multi-tier
applications under changing workload conditions.
相似文献
Qi ZhangEmail: |
59.
Luciana Cardoso Bonadia Fernando Augusto de Lima Marson Jose Dirceu Ribeiro Ilma Aparecida Paschoal Monica Corso Pereira Antonio Fernando Ribeiro Carmen Silvia Bertuzzo 《Gene》2014
Background
There are nearly 2000 cystic fibrosis transmembrane regulator (CFTR) mutations that cause cystic fibrosis (CF). These mutations are classified into six classes; on the one hand, the first three classes cause severe disease involvement in early childhood, on the other hand, the Class IV, V and VI mutations cause minor severe disease in the same age. Nowadays, with therapeutic advances in CF management and competence of pediatricians, physicians of adults have to deal with two groups of CF patients: (i) adults diagnosed in childhood with severe mutations and (ii) adults who initiated symptoms in adulthood and with Class IV, V and VI mutations. The aim of this study was to analyze adults from a clinical center, treated as CF disease, screening the CFTR genotype and evaluating the clinical characteristics.Methods
Thirty patients followed as CF disease at the University Hospital were enrolled. After a complete molecular CFTR negative screening and sweat test levels between 40 and 59 mEq/L, five patients were characterized as non-CF disease and were excluded. Molecular screening was performed by CFTR gene sequencing/MLPA or by specific mutation screening. Clinical data was obtained from medical records. The patients were divided into three groups: (1) patients with Class I, II and III mutations in two CFTR alleles; (2) genotype with at least one allele of Class IV, V or VI CFTR mutations and, (3) non-identified CFTR mutation + one patient with one allele with CFTR mutation screened (Class I).Results
There was an association of CFTR class mutation and sodium/chloride concentration in the sweat test (sodium: p = 0.040; chloride: p = 0.016), onset of digestive symptoms (p = 0.012), lung function parameter (SpO2 — p = 0.016), Bhalla score (p = 0.021), age at diagnosis (p = 0.008) and CF-related diabetes (p = 0.029). There was an association between Pseudomonas aeruginosa chronic colonization (as clinical marker for the lung disease status) and lung impairment (FEV1% — p = 0.027; Bhalla score — p = 0.021), CF-related diabetes (p = 0.040), chloride concentration in the sweat test (p = 0.040) and chronic infection by microorganisms (Staphylococcus aureus — p = 0.039; mucoid P. aeruginosa — p = 0.001). There is no positive association with the status of other clinical markers and the CFTR genotype groups. For clinical association with pancreatic insufficiency (as clinical marker for digestive symptoms), no association was related.Conclusion
The adults with CF diagnosed by sweat test have specific clinical and genotypic characteristics, being a population that should be studied to cause better future management. Some patients treated as CF disease by clinical symptoms, showed no disease, taking into account the sweat test and complete exon sequencing/MLPA screening. 相似文献60.