PDR节目数据库管理软件研究

为了适应PDR网络化、个人化的发展要求,本文提出了PDR节目数据库管理软件中一些关键模块的设计方案。这些方案包括实现节目列表的新型集合、符合MPEG-7标准的节目预告描述方案、统一的节目资源管理方案及其在提供电子节目单和完成预约录制方面的应用。实验证明以上各方案的性能均优于目前PDR产品所采用的相应方案。     

The content of phosphoinositides in the biological membranes of different types of muscle fibers

The content of phosphoinositids in biomembranes of slow (m.soleus) and fast (m. extensor digitorum longus) twitch muscular fibres (MF) was studied. Biochemical differences in different MF of fast and slow muscles were detected. The content of phosphotidylinosites in plasma membranes, mitochondrial and sarcoplasmic reticulum membranes of fast twitch MF was on average 1.28 times higher than in slow ones. The predominance of phosphatidylinositol-3,4,5-triphosphates in fast twitch MF over slow twitch MF was noted. The content of phosphatidylinoitol-3,4,5-triphosphates in plasma membranes, mitochondrial and sarcoplasmic reticulum membranes of slow twitch MF was 3, 2.35 and 1.25 times higher than in fast twitch MF. It was found that phosphoinositide content in biomembranes of different type MF was unequal which may be used to improve the expansion of understanding of the role of intracellular mediators in MF phenotype regulation.     

Limited importance of CD40/CD40L interaction in the B7-dependent generation of anti-MOPC-315 cytotoxic T lymphocyte activity by tumor bearer splenic cells stimulated in vitro in the presence of tumor necrosis factor

We have previously illustrated the importance of B7-2 expression for the enhanced generation of cytotoxic T lymphocyte (CTL) activity by stimulation cultures of tumor bearer splenic cells to which tumor necrosis factor alpha (TNFalpha) has been added. Here we show that the B7-1 molecule is also important for CTL generation by such stimulation cultures, although to a much lesser extent than the B7-2 molecule. In addition, we show the importance of CD40/CD40L interaction for the expression of the B7-2 molecule, but not the B7-1 molecule, by tumor bearer splenic cells stimulated in vitro in the presence of TNF. The CD40/CD40L interaction is also shown to be important for the generation of CTL activity by tumor bearer splenic cells stimulated in vitro in the presence of exogenous TNF. However, the CD40/CD40L interaction is less important for the generation of enhanced CTL activity than for the expression of an elevated level of B7-2. Specifically, blockade of CD40/CD40L interaction, which reduced the level of B7-2 expressed by tumor bearer splenic cells stimulated in vitro in the presence of TNF to the level of B7-2 expressed by tumor bearer splenic cells stimulated in vitro in the absence of exogenous TNF, failed to reduce the level of CTL generated to the level generated by tumor bearer splenic cells stimulated in the absence of exogenous TNF. Finally, blockade of CD40/CD40L interaction was inferior to blockade of B7-2/CD28 interaction in inhibiting the generation of CTL activity by tumor bearer splenic cells stimulated in the presence of exogenous TNF. Thus, although CD40/CD40L interaction is important for the generation of enhanced CTL activity by stimulation cultures of tumor bearer splenic cells to which TNF has been added, TNF also mediates its potentiating effect for CTL generation by such stimulation cultures via other mechanisms that are independent of CD40/CD40L interaction but dependent on B7-2 expression.     

A novel membrane protein is a mouse mammary tumor virus receptor

Mouse mammary tumor virus (MMTV) infects a number of different cell types, including mammary gland and lymphoid cells, in vivo. To identify the cellular receptor for this virus, a mouse cDNA expression library was transfected into Cos-7 monkey kidney cells, and those transfected cells able to bind virus were selected by using antibody against the virus's cell surface envelope protein, gp52. One clone isolated from a library prepared from newborn thymus RNA, called MTVR, was able to confer virus binding to both monkey and human cells; this binding was blocked by anti-MTVR antibody. Moreover, transfection of MTVR into CV1 cells rendered them susceptible to infection by a murine leukemia virus-based retrovirus vector pseudotyped with the MMTV envelope protein. An epitope-tagged MTVR cofractionated with cellular membranes. Coimmunoprecipitation of the MMTV envelope protein and a MTVR-rabbit Fc fusion protein showed that these two proteins bound to each other. The MTVR sequence clone is unique, shows no homology to known membrane proteins, and is transcribed in many tissues.