Cell responses to xenobiotics: comparison of MCF7 multi-drug- and mussel blood cell multi-xenobiotic-defense mechanisms

Multi-drug resistance (MDR) in MCF7 breast cancer cells and multi-xenobiotic resistance (MXR) in mussel (Mytilus edulis) blood cells (MBC) are well known mechanisms that contribute to the decrease in intracellular concentrations of many unrelated but cytotoxic compounds. In the present work, we have carried out comparative investigations of the MDR/MXR protective mechanisms using a rapid colorimetric assay for cell viability and calcein accumulation for MDR/MXR activities. These studies were performed using cultured MCF7 and MBC before and after in vitro exposure to xenobiotics. Our results indicate that a 5-day exposure to doxorubicin or vincristine decreased calcein accumulation in MBC which is consistent with an induction of multi-xenobiotic resistance. The increase in calcein accumulation provoked by 1-h treatment with 50 microM verapamil was much lower in MBC when compared to the P-glycoprotein overexpressing MCF7 cell line. We conclude that such microplate assays could be used in primary cultures of MBC to estimate the effects of various chemicals on MXR activity.     

苏北中部滨海平原成陆机制研究

苏北中部滨海平原位于废黄河三角洲和长江三角洲之间，其形成与全新世最大海侵之后长江、古黄河的供沙历史和供沙状况密切相关，并且现今海域南黄海辐射沙洲的辐聚点也位于这段海岸，故探讨其成陆机制具有重要意义。本文数值模拟了公元８世纪时该区的Ｍ２潮汐、潮流，在此基础上，计算了７种粒径泥沙在当时潮流场中的净输运状况，划分了海底冲淤区。计算结果表明，公元８世纪时苏北岸外存在大致以东台为顶点的辐射状古潮流场，其分布格局与现今苏北岸外大致以京港为顶点的辐射关潮流场基本一致，该辐射状潮流场的存在是由当时台东岸外的独特驻潮波波腹所决定的。进入苏北岸外古辐射状潮流场中的泥沙，在辐聚、辐散的潮流作用下，每一个潮周期均自ＮＥ、ＳＥ方向向东台附近海域净输运泥沙，在东台附近海域发生淤积。由此认为，苏北中部滨海平原是大致以东台为顶点的辐聚、辐散潮     

镉致鲫(Carassius auratus)外周血单个核细胞DNA损伤与增殖抑制

采用体内注射染镉的方法进行镉诱导鲫外周血单个核细胞(PBMC)DNA损伤与增殖抑制相关性的研究。将鲫(400g／尾)驯养4周后进行随机分组，每组5尾，以Cdh浓度1．25、2．50和3．75mg／kg腹腔注射染鲫，以生理盐水腹腔注射鲫为对照，染镉后0、3、5、7、10和14天取无菌抗凝鲫血，经淋巴细胞分离液离心分离获取PBMC，用单细胞凝胶电泳法检测PBMC的DNA损伤，用^3H-胸腺嘧啶脱氧核苷掺入法检测PBMC的增殖。结果表明，3天时各染镉组DNA迁移度增加，5天时继续加大并于7天时达到峰值，10天和14天时呈现逐渐减小的趋势。1．25mg／kg组与对照组在不同时间放射性活度(咖m)的差异均无显著性；0天和3天时各染镉组与对照组咖m的差异均无显著性；5天时2．50和3．75mg／kg组dpm明显下降，7天和10天时dpm与5天时基本相同，14天时dpm呈上升趋势。镉诱导DNA损伤与其抑制PBMC增殖相比，作用时间短且浓度低，初步推测镉诱导的DNA损伤是镉抑制PBMC增殖的重要机制之一。     

不同浓度亚油酸对日本对虾肝胰腺传代细胞磷含量的影响

在199培养基中加入促进细胞生长的亚油酸 ,对日本对虾(Penaeusjaponicus)肝胰腺细胞进行传代培养,测定传代细胞的总磷、无机磷含量。当亚油酸的加入量为16×10 -5mol/L时,细胞的总磷、有机磷含量均为最高。表明培养基中加入适量亚油酸 ,可促进日本对虾肝胰腺传代细胞的生长     

紫菜细胞悬浮培养

用酶解技术获得条斑紫菜离体细胞并对其进行细胞悬浮培养研究;对藻休不同部位的细胞分化发育方式,不同悬浮器具培养效果及不同起始培养的细胞密度进行了探索。结果表明:用气升式生物反应器培养细胞效果最佳,起始培养的细胞密度可达l×10~5细胞/ml,细胞存活率达85%。     

滨滩相互层土工程特性初步研究

对滨海相、河滩相互层土(粘性土、粉砂互层)的工程特性提出了系统认识,从理论上、实践上论证了互层土的稠度指标与现场标准贯入击数不协调的根本原因,并推荐了室内液性指数(IL)作必要折减的修正系数,以此按规范求取地基容许承载力,结果与标贯资料基本吻合。显然,修正后的IL不仅解决了测试指标相互间(IL与N)的矛盾,更重要的是客观上提高了地基强度,简化了施工工艺,产生了十分可观的经济社会效益。     

A NUMERICAL EXPERIMENT STUDY ON THE FORMING MECHANISMS OF LOW-LATITUDE CIRCULATION CELLS AND PRECIPITATION DURING AN EAST ASIAN COLD SURGE

The forming mechanisms of low-latitude circulation cells and precipitation during an East Asian cold surge have been studied by using a five-layer primitive equation model.Numerical experiments show that in mid-high latitudes,the propagation of the East Asian winter monsoon is nearly a dry process;in low-latitudes,the effects of cumulus convection intensify the northeast monsoon and northeast trade wind;however,they also prevent the intertropical convergence zone(ITCZ) from further southward invasion,and strengthen the meridional and zonal cells over East Asia. Numerical results also indicate that the winter monsoon precipitation in Indonesia and Northern Australia can exist independently.Both the South China Sea(SCS) cold surge and the West Pacific northeast cross-equatorial trade wind are of importance for the formation of the Northern Australia summer monsoon and its precipitation.Numerical results show that the development of cumulus convection,triggered by the SCS cold surge,is a crucial factor in forming the heavy monsoon precipitation and low-level stationary disturbances in Indonesia and Borneo.The tropical topography and northeast trade wind disturbances only affect the intensity of precipitation there.     

Seasonal variation in abundance and species composition of a planktonic diatom assemblage including viable cells on the bottom in matsushima bay,northeastern japan

Seasonal variation in abundance and species composition of a planktonic diatom assemblage distributed in the water column and also settled on the bottom was investigated for the shallow coastal water in Matsushima Bay on the Pacific coast of northeastern Japan during the period from October 1999 to September 2000. A spring bloom of diatoms began in April when nutrient concentrations started to increase, indicating the importance of nutrients. Viable cells of Skeletonema costatum and Thalassiosira spp., which were the dominant species in the water column throughout the year, were also always abundant in the bottom sediment. Both populations in the water column and on the bottom fluctuated essentially in parallel. For the planktonic diatoms in shallow coastal waters to maintain their vegetative populations in the water column, it would be advantageous for them to have a seeding population of viable cells on the bottom that are easily resuspended into the upper photic layer.     

Study of the Interaction between Biological Cells of Different Shapes and Sizes and Electromagnetic Fields Produced by Natural Phenomena

We carry out a study of the interaction between electromagnetic fields produced innature and cells with no structure but with different shapes and sizes, considered asapproximations of those observed in the human body. Magnetic fields produced byvarious atmospheric and geomagnetic phenomena are compared with the fieldsgenerated by the cells themselves. Working with frequencies up to 10⁵ Hz, we found that in most cases lightning is the natural phenomena capable of producingfield intensities comparable to those generated by the cells. As a first approximationwe assume that a cell might be affected only if a field of intensity comparable to thecell's field is present. Oscillating fields of less intensity and their harmonics can involveresonant interactions with the cells, however this situation is not considered here. Under the approximation of our study we found that the size and the shape are parameters of paramount importance: lightning represents a natural hazard only for the largest cells, while the quadrangular cells are not affected by any of the natural phenomena considered here.     

Hydrogen from coal: Production and utilisation technologies

Although coal may be viewed as a dirty fuel due to its high greenhouse emissions when combusted, a strong case can be made for coal to be a major world source of clean H₂ energy. Apart from the fact that resources of coal will outlast oil and natural gas by centuries, there is a shift towards developing environmentally benign coal technologies, which can lead to high energy conversion efficiencies and low air pollution emissions as compared to conventional coal fired power generation plant. There are currently several world research and industrial development projects in the areas of Integrated Gasification Combined Cycles (IGCC) and Integrated Gasification Fuel Cell (IGFC) systems. In such systems, there is a need to integrate complex unit operations including gasifiers, gas separation and cleaning units, water gas shift reactors, turbines, heat exchangers, steam generators and fuel cells. IGFC systems tested in the USA, Europe and Japan employing gasifiers (Texaco, Lurgi and Eagle) and fuel cells have resulted in energy conversions at efficiency of 47.5% (HHV) which is much higher than the 30–35% efficiency of conventional coal fired power generation. Solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are the front runners in energy production from coal gases. These fuel cells can operate at high temperatures and are robust to gas poisoning impurities. IGCC and IGFC technologies are expensive and currently economically uncompetitive as compared to established and mature power generation technology. However, further efficiency and technology improvements coupled with world pressures on limitation of greenhouse gases and other gaseous pollutants could make IGCC/IGFC technically and economically viable for hydrogen production and utilisation in clean and environmentally benign energy systems.