Cyclic AMP-dependent protein kinase (cAK) in human B cells: co-localization of type I cAK (RI alpha 2 C2) with the antigen receptor during anti-immunoglobulin-induced B cell activation

Cyclic AMP (cAMP) inhibits antigen-stimulated B cell proliferation through activation of cAMP-dependent protein kinases (cAK). We have examined the molecular composition and cellular localization of cAK in human B cells. We find that human B cells contain substantial amounts of mRNA for RI alpha, RII alpha, C alpha and C beta, barely detectable levels of RI beta mRNA, and no detectable RII beta or C gamma mRNA. At the protein level, using Western blotting and subunit-specific antibodies against the different R subunits, we find RI alpha and RII alpha, but no RI beta or RII beta. The presence of catalytic subunits was demonstrated using a nonselective anti-C antiserum. By photoaffinity labeling of R subunits with 8-azido-[32P]cAMP, followed by immunoprecipitation with subunit-specific antibodies, we were also able to demonstrate low levels of RI beta. Immunofluorescence staining of RI alpha and RII alpha demonstrates a rather homogeneous intracellular (but extranuclear) distribution of RI alpha, whereas the RII alpha subunits of cAK are localized to distinct perinuclear structures, previously identified as centrosomes in other cell types. Upon anti-Ig-mediated capping of B cells, RI alpha subunits redistribute to the cap, co-localizing with the antigen-receptors, whereas the intracellular localization of RII alpha subunits remains unchanged.     

Mitosis-specific phosphorylation and subcellular redistribution of the RIIalpha regulatory subunit of cAMP-dependent protein kinase

Phosphorylation of the RII regulatory subunits of cyclic AMP-dependent protein kinases (PKAs) was examined during the HeLa cell cycle. Three RIIalpha isoforms of 51, 54, and 57 kDa were identified by RIIalpha immunodetection and labeling with 8-azido[32P]cAMP in different cell cycle phases. These isoforms were characterized as different phosphorylation states by the use of selective PKA and cyclin-directed kinase inhibitors. Whereas RIIalpha autophosphorylation by PKA caused RIIalpha to shift from 51 to 54 kDa, phosphorylation of RIIalpha by one other or a combination of several kinases activated during mitosis caused RIIalpha to shift from 51 to 57 kDa. In vivo incorporation of [32P]orthophosphate into mitotic cells and RIIalpha immunoprecipitation demonstrated that RIIalpha was hyperphosphorylated on a different site than the one phosphorylated by PKA. Deletion and mutation analysis demonstrated that the cyclin B-p34(cdc2) kinase (CDK1) phosphorylated human recombinant RIIalpha in vitro on Thr54. Whereas RIIalpha was associated with the Golgi-centrosomal region during interphase, it was dissociated from its centrosomal localization at metaphase-anaphase transition. Furthermore, particulate RIIalpha from HeLa cell extracts was solubilized following incubation with CDK1 in vitro. Our results suggest that at the onset of mitosis, CDK1 phosphorylates RIIalpha, and this may alter its subcellular localization.     

Compositional Factors Affecting Protective Alumina Formation Under Type II Hot Corrosion Conditions

The Type II (700 °C) hot corrosion resistance of Ni–36Al (at.%) base alloys with various additions of Pt, Co, and/or Cr was investigated. It was found that the addition of either 5 at.% Pt or 5 at.% Cr was highly beneficial, i.e., extended the protective incubation stage. This was shown, via a thorough examination of the scales formed on these alloys during 700 °C oxidation, to be due to an enhanced ability to rapidly form a protective, pure Al₂O₃ scale. Addition of either 5 at.% Cr or 5 at.% Co to a Ni–36Al–5Pt alloy was found to be highly detrimental. These latter results are explained by examining subsurface phase transformations that occur during exposure; extensive transient oxidation was also found to play a significant role in the presence of Co.     

Application of Small Computers in Construction

The deliberations of the ASCE Task Committee on the Application of Small Computers in Construction are presented. The paper first identifies needs that are stimulating the application of small computers in construction, and then examines their present and potential utilization in several representative application areas. Applications include accounting and payroll, estimating, field office administration, contract language retrieval, electronic communications, scheduling, process simulation, graphical reporting, computer‐aided design, and process control. The role that ASCE might take in supporting the effective application of small computers in construction practice is considered. Possibilities include participation in the development of standards, education of practitioners, stimulation of innovative techniques, liaison with other organizations, input to computer manufacturers and software developers about specific needs and requirements in construction, studying the organizational and behavioral aspects of computers in construction, and input to ASCE awards committees about meritorious work in this area. It is concluded that an ongoing ASCE Construction Division committee is needed to monitor and influence the effective application of this rapidly evolving small computer technology in construction.     

The Effect of Microstructure on the Type II Hot Corrosion of Ni-Base MCrAlY Alloys

Alloys of compositions (in wt%) Ni–31.5Cr–11.5Al–0.6Y and Ni–20.9Co–19.2Cr–12.5Al–0.5Y–0.4Si–0.3Hf were prepared using three different processing routes and exposed to Type II (700 °C) hot corrosion conditions in order to evaluate the influence of microstructural scale on degradation resistance. The alloys were prepared in bulk form by drop casting (DC) and injection casting (IC), and as a coating by low-pressure plasma spraying (LPPS) on a René N5 superalloy substrate. The resulting microstructures became coarser in the order LPPS < IC < DC for the NiCoCrAlY, and IC < LPPS < DC for the NiCrAlY. The DC and LPPS NiCrAlY displayed very good resistance to Type II hot corrosion; however, rapid Type II attack was observed when the alloy was prepared by the IC process. The LPPS and IC NiCoCrAlY formed more protective scales than the DC NiCoCrAlY, i.e., Type II hot corrosion resistance increased with microstructural refinement. Pre-oxidation of a cast NiCoCrAlY alloy greatly reduced the amount of Type II attack for the exposure times studied. The localized attack of the pre-oxidized specimens was found to initiate at reactive-element-rich regions in the pre-formed scale.     

Nondestructive Evaluation of Drilled Shafts

The Deep Foundations Committee of the Geo-Institute commissioned a task force, chaired by Alan Macnab, to evaluate the state of the practice of Nondestructive Evaluation of Drilled Shafts. The task force consisted of: ??2 researchers on the topic—Al Dimillio of the Federal Highway Administration and Dr. Michael O'Neill of the University of Houston ??1 academic—Dr. Richard Finno of Northwestern University ??4 representatives of testing firms—Frank Rausche of Goble Rausche Likins & Assoc., Inc.; Dr. Allen Davis of CTL Construction Technology Laboratories, Inc.; Bernard Hertlein of STS Consultants, Ltd.; and Larry Olson of Olson Engineering, Inc. ??2 owners' representatives—Robert Stott of Caltrans and Barry Berkovitz of the Federal Highway Administration ??3 contractors—Bill Starke of Deep Foundation, Ltd.; Tim Smith of Malcolm Drilling Co., Inc.; and Alan Macnab of Condon Johnson & Assoc., Inc. This report was previously published in the May 1988 issue of Foundation Drilling. It is being republished here to bring this consensus state-of-the-practice information to the attention of the entire geotechnical engineering profession and to invite feedback through the regular discussion section of the Journal.     

A new model for the human alimentary tract: the work of a Committee 2 task group

The absorbed doses received from ingested radionuclides are currently calculated using the method outlined in ICRP Publication 30. It has been recognised by the ICRP that some of the assumptions used to calculate absorbed doses should be reviewed. A new physiologically based model has been developed, applicable to intakes of radionuclides in food and liquids by children and adults. All parts of the alimentary tract are included, additional sites for absorption and retention are considered and the morphometric and transit parameter values are reviewed in coordination with the ICRP Reference Man revision. Features of the new model are explained and preliminary dose estimates are presented.