We developed a quartz crystal biosensor designed to detect concentrations and ligand affinity parameters of free unlabeled proteins in real time. Using a model system with human IgE as the analyte and single-stranded DNA aptamers or an anti-IgE antibody as immobilized ligands, we could demonstrate that aptamers were equivalent to antibodies in terms of specificity and sensitivity. Both receptor types selectively detected 0.5 nmol/L of IgE. In addition, the aptamer receptors tolerated repeated affine layer regeneration after ligand binding and recycling of the biosensor with little loss of sensitivity. Because of the small size and nonprotein nature of the aptamers, they were immobilized in a dense, well-oriented manner, thus extending the linear detection range to 10-fold higher concentrations of IgE. In addition to demonstrating for the first time that an aptamer-based biosensor can specifically and quantitatively detect an analyte in various complex protein mixes, the aptamer-ligand proved to be relatively heat resistant and stable over several weeks. Since aptamers consist of nucleic acids, well-established chemistry can be applied to produce optimized affine layers on biosensors that may be developed to specifically detect proteins in solution for analysis of proteomes.

The article contains sections titled: 1. Introduction 2. Properties 2.1. Physical Properties 2.2. Chemical Properties 3. Raw Materials 3.1. Natural Resources 3.2. Tungsten Scrap 4. Production 4.1. Ore Beneficiation 4.2. Pretreatment of Ore Concentrates and Scrap 4.3. Hydrometallurgy 4.3.1. Digestion 4.3.2. Purification 4.3.3. Conversion of Sodium Tungstate Solution to Ammonium Tungstate Solution 4.3.3.1. Solvent Extraction 4.3.3.2. Ion Exchange Process 4.3.4. Crystallization of Ammonium Paratungstate (APT) 4.4. Calcination of APT 4.5. Reduction by Hydrogen to Tungsten Metal Powder 4.6. Production of Compact Metal 4.7. Processing of Sintered Parts 4.7.1. Shaping 4.7.2. Mechanical Bonding of Tungsten to Tungsten and Other Metals 4.8. Surface Treatment 4.9. Tungsten Coatings 4.10. Production of High‐Purity Tungsten Metal (99.999 ‐ 99.9999 %) 5. Tungsten Alloys 5.1. Single‐Phase Mixed‐Crystal Alloys 5.2. Multiple Phase Alloys 6. Uses 7. Analysis 7.1. Raw Materials 7.2. High‐Purity Intermediate Products, Tungsten Powder, and Compact Tungsten Metal 7.3. Trace Elements in High‐Purity Tungsten Metal 8. Ferrotungsten and Related Alloys 8.1. Composition 8.2. Uses 8.3. Production 8.3.1. Ferrotungsten 8.3.1.1. Carbothermic Production 8.3.1.2. Carbothermic and Silicothermic Production 8.3.1.3. Metallothermic Production 8.3.2. Production of Tungsten Melting Base and Tungsten Master Alloys 9. Compounds 9.1. Tungsten Chemistry 9.2. Aqueous Solutions of Tungsten 9.3. Intermetallic Compounds 9.4. Compounds with Nonmetals 9.4.1. Tungsten ‐ Boron Compounds 9.4.2. Tungsten ‐ Carbon Compounds 9.4.3. Tungsten ‐ Silicon Compounds 9.4.4. Tungsten ‐ Group 15 Compounds 9.4.5. Tungsten ‐ Oxygen Compounds 9.4.6. Tungsten ‐ Chalcogenide Compounds 9.4.7. Tungsten ‐ Halogenide Compounds 10. Tungsten in Catalysis 11. Economic Aspects 12. Tungsten Recycling 13. Beneficial Effects on Human Health 14. Toxicology and Occupational Health 15. Acknowledgement

We have recently shown that the adenovirus type 5 E4orf6 protein interacts with the cellular tumor suppressor protein p53 and blocks p53 transcriptional functions. Here we report that the E4orf6 protein can promote focus formation of primary rodent epithelial cells in cooperation with adenovirus E1A and E1A plus E1B proteins. The E4orf6 protein can also inhibit p53-mediated suppression of E1A plus E1B-19kDa-induced focus formation. Mutant analysis of the E4orf6 protein demonstrates that these activities correlate with the ability of the adenovirus protein to relieve transcriptional repression mediated by the carboxyl-terminal region of p53 in transient transfection assays. We further demonstrate that expression of wild-type E4orf6 correlates with a dramatic reduction of p53 steady-state levels in transformed rat cells. Our data demonstrate that adenovirus type 5 encodes two different proteins, E1B-55kDa and E4orf6, that bind to p53 and contribute to transformation by modulating p53 transcriptional functions.