Cells secreting antibodies originate from cells secreting immunoglobulins without a detectable antibody function for the antigen injected]

Cells secreting immunoglobulins without detectable antibody function arising after an injection of horseradish peroxidase were micromanipulated from the center of haemolytic plaques of Sheep red blood cells coated with anti-Ig antibodies. These cells were cultured individually for 48 hrs, with irradiated cells as feeder layer and in the presence of the immunogen and of LPS. It was shown that after this time 22% of the immunoglobulin-secreting cells had generated antiperoxidase antibody-secreting cells or were transformed into antibody-secreting cells.     

Persistence of Mycobacterium tuberculosis in macrophages and mice requires the glyoxylate shunt enzyme isocitrate lyase

Mycobacterium tuberculosis claims more human lives each year than any other bacterial pathogen. Infection is maintained in spite of acquired immunity and resists eradication by antimicrobials. Despite an urgent need for new therapies targeting persistent bacteria, our knowledge of bacterial metabolism throughout the course of infection remains rudimentary. Here we report that persistence of M. tuberculosis in mice is facilitated by isocitrate lyase (ICL), an enzyme essential for the metabolism of fatty acids. Disruption of the icl gene attenuated bacterial persistence and virulence in immune-competent mice without affecting bacterial growth during the acute phase of infection. A link between the requirement for ICL and the immune status of the host was established by the restored virulence of delta icl bacteria in interferon-gamma knockout mice. This link was apparent at the level of the infected macrophage: Activation of infected macrophages increased expression of ICL, and the delta icl mutant was markedly attenuated for survival in activated but not resting macrophages. These data suggest that the metabolism of M. tuberculosis in vivo is profoundly influenced by the host response to infection, an observation with important implications for the treatment of chronic tuberculosis.     

Dilution of phosphate in the plasma of tocopherol deficient rabbits

Résumé L'étude de la cinétique de la dilution du phosphate dans le plasma des lapins déficients en-tocophérol a mis en évidence que, chez ces animaux, la vitesse de disparition du phosphate du plasma ainsi que l'espace de phosphate se trouvent augmentés.     

A large-cavity zeolite with wide pore windows and potential as an oil refining catalyst

Crude oil is an important feedstock for the petrochemical industry and the dominant energy source driving the world economy, but known oil reserves will cover demand for no more than 50 years at the current rate of consumption. This situation calls for more efficient strategies for converting crude oil into fuel and petrochemical products. At present, more than 40% of oil conversion is achieved using catalysts based on faujasite; this zeolite requires extensive post-synthesis treatment to produce an ultrastable form, and has a large cavity accessible through four 0.74-nm-wide windows and thus limits the access of oil molecules to the catalytically active sites. The use of zeolites with better accessibility to their active sites should result in improved catalyst efficiency. To date, two zeolites with effective pore diameters exceeding that of faujasite have been reported, but their one-dimensional pore topology excludes use in oil refining. Similarly, zeolites with large pores and a three-dimensional pore topology have been reported, but in all these materials the pore openings are smaller than in faujasite. Here we report the synthesis of ITQ-21, a zeolite with a three-dimensional pore network containing 1.18-nm-wide cavities, each of which is accessible through six circular and 0.74-nm-wide windows. As expected for a zeolite with this structure, ITQ-21 exhibits high catalytic activity and selectivity for valuable products in preliminary oil refining tests.     

对导师负责制下研究生德育的思考

研究生德育的加强与改善有利于高层次人才地培养.本文论述了导师负责制下研究生德育的特点和当前研究生德育中存在的问题,并结合导师负责制提出了以导师为主体,研究生院、院系协调配合的德育新机制.     

均匀纺锤形α-FeO(OH)微晶形成过程的动力学研究

对用Na_2CO_3作沉淀剂,在FeSO_4水溶液中形成的Fe(OH)_2和FeCO_3的悬浮液中鼓入空气,制备均匀纺锤形α-FeO(OH)微晶的动力学过程进行了研究。证明α-FeO(OH)微晶形成经过了晶核的形成过程和晶核的长大过程。考察了原料起始浓度、反应温度、空气流量对微晶形成过程的影响,文中首次提出利用α-FeO(OH)相形成过成的Avrami数n值来控制α-FeO(OH)微晶轴比大小的方祛,并使用似稳定浓度法确定了晶核长大过程氧化反应的速率方程。     

均匀纺锤形γ-Fe_2O_3磁粉制备过程热处理工艺的研究

利用FeSO_4和Na_2CO_3为原料制备的均匀纺锤形α-FeOOH微晶,在流态化床中,进行了脱水、还原(以汽相无水乙醇为还原剂)、部分氧化等热处理工艺的研究。实验确定,脱水温度越高,最终产物的磁性能也越高;而还原温度、氧化温度提高,最终产物的磁性能下降。该文对热处理工艺影响的原因也进行了探讨。