Mutational analysis of the A-kinase anchoring protein (AKAP)-binding site on RII. Classification Of side chain determinants for anchoring and isoform selective association with AKAPs

Compartmentalization of the type II cAMP-dependent protein kinase is conferred by interaction of the regulatory subunit (RII) with A-Kinase Anchoring Proteins (AKAPs). The AKAP-binding site involves amino-terminal residues on each RII protomer and is formed through dimerization. A site-directed mutagenesis strategy was utilized to assess the contribution of individual residues in either RII isoform, RIIalpha or RIIbeta, for interaction with various anchoring proteins. Substitution of long-chain or bulky hydrophobic groups (leucines or phenylalanines) for isoleucines at positions 3 and 5 in RIIalpha decreased AKAP-binding up to 24 +/- 3 (n = 8)-fold, whereas introduction of valines had minimal effects. Replacement with hydrophilic residues (serine or asparigine) at both positions abolished AKAP binding. Mutation of proline 6 in RIIalpha reduced binding for four AKAPs (Ht31, MAP2, AKAP79, and AKAP95) from 2.3 to 20-fold (n = 4) whereas introduction of an additional proline at position 6 in RIIbeta increased or conferred binding toward these anchoring proteins. Therefore, we conclude that beta-branched side chains at positions 3 and 5 are favored determinants for AKAP-binding and prolines at positions 6 and 7 increase or stabilize RIIalpha interaction with selected anchoring proteins.     

The treatment of peptic ulcer patients during exacerbation at the day hospital of an industrial enterprise polyclinic

Results are submitted of treatment of 659 patients with exacerbated peptic ulcer at an in-plant day in-patient facility. The basic therapy was hyperbaric oxygenation and ultraviolet irradiation of blood. The relapse rate over the year was 16%. A surgical operation was performed in 1.5% of those cases having completed the course treatment at the day in-patient facility, with 33.3% of patients having been operated on urgently, and 11.28% at a twenty-four-hour department; of these, in 85.62% cases operations were performed in situations of emergency needing prompt action. Duration of temporary disability in patients cared for at the day hospital was 21.3 days, while in those treated at a twenty-four-hour facility-27.8 days. Indications for hospitalization were of social character. Comparison of results of treatment, relapse rates and complications of ulcer disease in hospitalized patients versus those having been treated at a day-care facility gave arguments in favour of reorientation of treatment of major part of those patients experiencing exacerbation of ulcer disease at well equipped day-care in-patient facilities.     

Experimental characterization of electron-hole generation in silicon carbide

Thermal generation in wide bandgap semiconductors can be observed by monitoring the capacitance recovery transients of npn (or pnp) storage capacitors in which the middle layer is floating. In this article, we report a study of thermal generation in 4H and 6H silicon carbide (SiC). Three generation mechanisms are identified: bulk generation in the depletion regions of the pn junctions, surface generation at the periphery of the capacitors, and defect generation associated with imperfections in the material. All three generation mechanisms are thermally activated. Bulk generation and surface generation have activation energies of approximately half bandgap, while defect generation exhibits field-induced barrier lowering resulting in an apparent activation energy less than half bandgap. Because the generation rate is extremely low, most measurements are conducted at elevated temperatures (250-350°C). However, we also describe a long-term measurement at room temperature in which the 1/e recovery time appears to be in excess of 100 years.