Tyrosine phosphorylation of the Kv1.3 potassium channel

Kv1.3, a voltage-dependent potassium channel cloned from mammalian brain and T lymphocytes, contains multiple tyrosine residues that are putative targets for tyrosine kinases. We have examined the tyrosine phosphorylation of Kv1.3, expressed transiently in human embryonic kidney (or HEK) 293 cells, by endogenous and coexpressed tyrosine kinases. Tyrosine phosphorylation is measured by a strategy of immunoprecipitation followed by. Western blot analysis, using antibodies that specifically recognize Kv1.3 and phosphotyrosine. Coexpression of the constitutively active tyrosine kinase v-src, together with Kv1.3, causes a large increase in the tyrosine phosphorylation of the channel protein. This phosphorylation of Kv1.3 can be reversed by treatment with alkaline phosphatase before Western blot analysis. Coexpression with a receptor tyrosine kinase, the human epidermal growth factor receptor, also causes an increase in tyrosine phosphorylation of Kv1.3. The effects of endogenous tyrosine kinases were examined by treating Kv1.3-transfected cells with the specific membrane-permeant tyrosine phosphatase inhibitor pervanadate. Pervanadate treatment causes a time- and concentration-dependent increase in the tyrosine phosphorylation of Kv1.3. This increased tyrosine phosphorylation of Kv1.3 is accompanied by a time-dependent decrease in Kv1.3 current, measured by patch-clamp analysis with cell-attached membrane patches. The pervanadate-induced suppression of current and much of the channel tyrosine phosphorylation are eliminated by mutation of a specific tyrosine residue, at position 449 of Kv1.3, to phenylalanine. Thus, there is a continual phosphorylation and dephosphorylation of Kv1.3 by endogenous kinases and phosphatases, and perturbation of this constitutive phosphorylation/dephosphorylation cycle can profoundly influence channel activity.     

Effect of hydroxyures and amethopterin on radiosensitivity and thiol levels in biologic objects]

The use of the standard chemical technic for measuring intestinal glucose absorption was compared with a new double-label radioisotope technic. Glucose absorption and water flux in the mouse small intestine were measured by both methods. The results indicated that the 2 approaches yield almost identical values. The radioisotope technic utilized [14C] polyethylene glycol to measure water flux and [3H] glucose. The technic was found to be reliable, rapid, and applicable to small samples and other substrates. It is particularly suited to absorption studies in small animals such as the mouse, where sample size is limited. The study also showed that the polyethylene glycol recovery rate from the mouse intestine was 97.8%, indicating that it is a valid absorption marker in this species.     

Ratio of glycan to teichoic acid in Actinomyces thermovulgaris cell wall

The molar ratio between glycan and teichoic acid was studied in the cell wall of Actinomyces thermovulgaris. A chain of teichoic acid consisting of 13 glycerophosphate units was found to correspond to 6--7 disaccharide units of glycan. The cell wall contains 31% of the glycan of the glycopeptide and 25% of teichoic acid. The content of glycan was calculated using the concentration of muramic acid in the wall. The cell wall was found to contain 1.02% of O-acetyl groups.     

Current concepts of the dentogingival junction: the epithelial and connective tissue attachments to the tooth

This review leads to a concept in which the tissues of the dentogingival junction are dynamic rather that static. Even when they are pathologic, they can be reconstituted by repair. Both their cellular and extracellular components exhibit a high rate of turnover. Some of the cells are specialized for specific functions, such as attachment formation, and do not generate additional cells, but generative pools are always nearby. The cells are capable of movement and of positional change. The junctional epithelium can advance and retract. The cuticle width is alterable. The entire tissue is capable of regeneration after wounding. This dynamic group of tissues is well adapted for the healing of direct injuries produced during mastication. The tissues do remarkably well, over long periods, in their response to periodontal disease, whether due to direct bacterial or toxic damage, or to indirect damage via the migration of inflammatory cells into the lesion. The tissues show a capacity for repair and regeneration following the elimination of plaque formation and the resultant resolution of the inflammatory infiltrate. The complete story is not yet developed. The past 60 years are replete with fine contributions by distinguished workers. Additional contributions continue to be made. The inheritance from our predecessors has been used well and our expanded knowledge in this area now serves as the conceptual framework for further study.     

Medical provisions for the immediate post-flight period following long space flights

At the final stage of long-term space flights first aid should be rendered in a specific way in cases of critical situations. Resuscitation and anesthesiology measures should be applied, if necessary, after study of flight-induced changes in the vital organs and systems. The paper describes the most important factors that should determine the tactics of resuscitation-anesthesiology support of the immediate postflight stage, if theoretically feasible acute life-endangering states develop. It also presents substantiated correction of routine clinical protocols of resuscitation aid.     

On doubting and certainty

Eggs from four species of aquatic birds inhabiting waterways of the Lake St. Clair region were collected in 1973 and analyzed for mercury. Species analyzed were mallard ducks (Anas platyrhynchos), common terns (Sterna hirundo), black-crowned night herons (Nycticorax nycticorax), and great egrets (Casmerodius albus). Mallard eggs contained relatively low residue levels, less than 0.05-0.26 ppm, and common tern eggs contained the highest residues, ranging up to 1.31 ppm. Mercury levels in the eggs were appreciably lower than those in the same species in 1970. The declines are attributed to the 1970 restrictions placed on industrial discharges of mercury into the St. Clair and Detroit Rivers.     

Septic arthritis following Staphylococcus aureus infection in mice lacking inducible nitric oxide synthase

Nitric oxide (NO), produced in large amounts by inducible NO synthase (iNOS), has emerged recently as an important microbicidal and immunomodulatory mediator. We have investigated its role in bacterial septic arthritis caused by Staphylococcus aureus infection using iNOS-deficient mice. The incidence, rate of development, and severity of arthritis were greater in iNOS-deficient than in heterozygous or wild-type control mice. Similarly, the incidence and severity of septicemia and mortality were significantly higher in iNOS-deficient mice compared with controls. Increased TNF-alpha synthesis in vivo and in vitro and enhanced IFN-gamma compared with IL-4 production in vitro in iNOS-mutant mice demonstrated exaggerated Th1 polarization of the host response. These data indicate that high output NO production is not a prerequisite for severe articular destruction and imply that NO is of importance in synovial defense against staphylococcal infection.