No abstract

Many viruses utilize the cellular transcription apparatus to express their genomes, and they encode transcriptional regulatory proteins that modulate the process. Here we review the current understanding of three viral regulatory proteins. The adenovirus E1A protein acts within the nucleus to regulate transcription through its ability to bind to other proteins. The herpes simplex type 1 virus VP16 protein acts within the nucleus to control transcription by binding to DNA in conjunction with cellular proteins. The human T-cell leukemia virus Tax protein influences transcription through interactions with cellular proteins in the nucleus as well as the cytoplasm.

Multicellular glial calcium waves may locally regulate neural activity or brain energetics. Here, we report a diffusion-driven astrocytic signal in the normal, intact brain that spans many astrocytic processes in a confined volume without fully encompassing any one cell. By using 2-photon microscopy in rodent cerebellar cortex labeled with fluorescent indicator dyes or the calcium-sensor protein G-CaMP2, we discovered spontaneous calcium waves that filled approximately ellipsoidal domains of Bergmann glia processes. Waves spread in 3 dimensions at a speed of 4 -11 m/s to a diameter of Ϸ50 m, slowed during expansion, and were reversibly blocked by P2 receptor antagonists. Consistent with the hypothesis that ATP acts as a diffusible trigger of calcium release waves, local ejection of ATP triggered P2 receptor-mediated waves that were refractory to repeated activation. Transglial waves represent a means for purinergic signals to act with local specificity to modulate activity or energetics in local neural circuits.astrocytes ͉ Bergmann glia ͉ in vivo ͉ 2-photon microscopy ͉ G-CaMP2

A novel process is discussed for producing a wide variety of ceramic powders with unique physical and chemical characteristics. Silicon, Si3N4, and SiC powders were produced from CO2 laser‐heated gas‐phase reactants; a detailed description of this laser‐driven process is presented. The physical, chemical, and crystalline nature of the resultant powders and the effect of process variables are discussed in Part II. In this process, reactant gases are rapidly heated by CO2 laser radiation and decompose, causing particles to nucleate and grow rapidly. Analytical models of fluid flow, heat transfer, heating rates, and powder‐formation mechanisms are discussed. The powders produced in this process are very fine (<0.1μm), spherical, nearly monodispersed in size, extremely pure, and loosely agglomerated.

No abstract

No abstract

No abstract

No abstract