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Biomedical subjects

R C Walsh

Publications and source records attributed to R C Walsh.

6 recordsLinked to original sources
PubMed2001

Exercise increases serum Hsp72 in humans.

Recent evidence suggests that heat shock proteins (Hsps) may have an important systemic role as a signal to activate the immune system. Since acute exercise is known to induce Hsp72 (the inducible form of the 70-kDa family of Hsp) in a variety of tissues including contracting skeletal muscle, we hypothesized that such exercise would result in the release of Hsp72 from stressed cells into the blood. Six humans (5 males, 1 female) ran on a treadmill for 60 minutes at a workload corresponding to 70% of their peak oxygen consumption. Blood was sampled from a forearm vein at rest (R), 30 minutes during exercise, immediately postexercise (60 minutes), and 2, 8, and 24 hours after exercise. These samples were analyzed for serum Hsp72 protein. In addition, plasma creatine kinase (CK) was measured at these time points as a crude marker of muscle damage. With the exception of the sample collected at 30 minutes, muscle biopsies (n = 5 males) were also obtained from the vastus lateralis at the time of blood sampling and analyzed for Hsp72 gene and protein expression. Serum Hsp72 protein increased from rest, both during and after exercise (0.13 0.10 vs 0.87+/-0.24 and 1.02+/-0.41 ng/mL at rest, 30 and 60 minutes, respectively, P < 0.05, mean SE). In addition, plasma CK was elevated (P < 0.05) 8 hours postexercise. Skeletal muscle Hsp72 mRNA expression increased 6.5-fold (P < 0.05) from rest 2 hours postexercise, and although there was a tendency for Hsp72 protein expression to be elevated 2 and 8 hours following exercise compared with rest, results were not statistically significant. The increase in serum Hsp72 preceded any increase in Hsp72 gene or protein expression in contracting muscle, suggesting that Hsp72 was released from other tissues or organs. This study is the first to demonstrate that acute exercise can increase Hsp72 in the peripheral circulation, suggesting that during stress these proteins may indeed have a systemic role.

Adult↗
PubMed1993

Structure and expression of hybrid dysgenesis-induced alleles of the ovarian tumor (otu) gene in Drosophila melanogaster.

Mutations at the ovarian tumor (otu) gene of Drosophila melanogaster cause female sterility and generate a range of ovarian phenotypes. Quiescent (QUI) mutants exhibit reduced germ cell proliferation; in oncogenic (ONC) mutants germ cells undergo uncontrolled proliferation generating excessive numbers of undifferentiated cells; the egg chambers of differentiated (DIF) mutants differentiate to variable degrees but fail to complete oogenesis. We have examined mutations caused by insertion and deletion of P elements at the otu gene. The P element insertion sites are upstream of the major otu transcription start sites. In deletion derivatives, the P element, regulatory regions and/or protein coding sequences have been removed. In both insertion and deletion mutants, the level of otu expression correlates directly with the severity of the phenotype: the absence of otu function produces the most severe QUI phenotype while the ONC mutants express lower levels of otu than those which are DIF. The results of this study demonstrate that the diverse mutant phenotypes of otu are the consequence of different levels of otu function.

Alleles↗
PubMed1984

Identification and characterization of some bacterial membrane sulfhydryl groups which are targets of bacteriostatic and antibiotic action.

Covalent modification of sulfhydryl groups which become sensitive toward sulfhydryl agents during germination of Bacillus cereus spores exerts a profound bacteriostatic effect, resulting in outgrowth inhibition. The modified spore components are membrane species of 13,000, 28,000, and 29,000 daltons. Detergent disruption of the membrane inactivated the sulfhydryl groups. A highly sigmoid inhibition curve (n = 11.8) with diamide suggested the participation of closely neighboring sulfhydryl groups. Substate and substrate analogs of the lactose and dicarboxylic acid permeases protected the sulfhydryl groups against modification. Nisin, a 34-residue peptide antibiotic, inhibited spore outgrowth and sulfhydryl modification at a concentration of about 0.1 microM. Since these sulfhydryl groups have been implicated as involved with the bacteriostatic action of nitrite, substances directed toward them may be a useful new class of bacteriostatic agents and antibiotics.

Anti-Bacterial Agents↗
PubMed1982

Dihydrocytochalasin B disorganizes actin cytoarchitecture and inhibits initiation of DNA synthesis in 3T3 cells.

Dihydrocytochalasin B (H2CB) disrupts the actin structure of Swiss/3T3 mouse fibroblasts and inhibits the ability of serum growth factors to stimulate DNA synthesis in quiescent cultures. Low doses of H2CB (2-10 X 10(-7) M) added to serum-arrested cells reversibly block initiation of DNA synthesis by serum; by epidermal growth factor and insulin; or by epidermal growth factor, fibroblast growth factor and insulin. H2CB is effective only when added to cells within 8-10 hr after stimulation. Low doses of H2CB cause cell rounding and a loss of actin microfilament bundles, but they do not interfere with glucose or thymidine transport. These results suggest that stimulation of 3T3 cells involves at least one obligatory actin-mediated step. Transformed cells appear to obviate this step, for H2CB does not inhibit the entry into S phase of SV40-transformed or Moloney murine sarcoma virus-transformed 3T3 cells synchronized by mitotic shake-off.

Actins↗