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F Walton

Publications and source records attributed to F Walton.

18 recordsLinked to original sources
PubMed1995

Expression of the SmpA outer membrane lipoprotein of Serpulina hyodysenteriae strain P18A in vivo.

An ELISA has been developed using a monoclonal antibody (F325 AC4) to the SmpA surface lipoprotein of Serpulina hyodysenteriae strain P18A when grown in vitro. The lower level of detection of the ELISA was approximately 5 x 10(6) spirochaetes/ml when spirochaetes were either resuspended in phosphate buffered saline or in pig faeces. When pigs were challenged with S. hyodysenteriae strain P18A the lipoprotein was detected in the faeces of pigs by ELISA when the numbers of spirochaetes excreted was greater than 10(6) per g of faeces. After onset of clinical signs in the pig, expression of SmpA was not detected by ELISA or by Western blotting using either monoclonal antibody F325 AC4 or polyclonal antiserum B50 against the SmpA antigen. However, when the in vivo grown spirochaetes were subsequently cultured in vitro expression of SmpA was detected by Western blotting. In the mouse model of swine dysentery S. hyodysenteriae spirochaetes obtained from mice with gross lesions also did not express SmpA. It was concluded that the apparent lack of expression may have been the result of environmental regulation of gene expression or antigenic variation and was not due to denaturation of the antigen in vivo.

Animals↗
PubMed1991

Staurosporine inhibits neutrophil phagocytosis but not iC3b binding mediated by CR3 (CD11b/CD18).

C receptor CR3 (iC3b-receptor, CD11b/CD18) plays an essential role in several phagocytic and adhesive neutrophil functions. Recent evidence suggests that stimulus-induced phosphorylation of the CR3 beta-chain, CD18, may mediate certain neutrophil functions by transiently converting the molecule to an activated state. Staurosporine, a protein kinase C inhibitor that blocks PMA-induced CD18 phosphorylation, was used to study the functional relevance of this event. Neutrophils adhered to glass were assayed for binding and phagocytosis of iC3b-opsonized sheep E (EC3bi) in the presence or absence of PMA and/or staurosporine. Binding of EC3bi was markedly increased, not only by PMA, but also by staurosporine and by a combination of both agents (three- to sevenfold). The enhancement of rosetting by staurosporine was likely caused by increased surface expression of CR3 via exocytosis of specific granular contents. In contrast, staurosporine alone did not stimulate phagocytosis of EC3bi and markedly inhibited PMA-induced phagocytosis. Staurosporine also inhibited phagocytosis of yeast beta glucan particles, a CR3 ligand that, in contrast to EC3bi, is bound and ingested without additional prior treatment with PMA. beta glucan phagocytosis was associated with a low level of CD18 phosphorylation. Staurosporine did not block phagocytosis in general, because this agent had relatively little effect on FcR-mediated phagocytosis. These data demonstrate that phagocytosis mediated by CR3 requires activation of CR3 via a staurosporine-sensitive pathway. Increased binding of EC3bi, a function of increased surface expression of CR3, does not require activation of CR3 by such a pathway, confirming previous evidence for the independence of these two phenomena. A direct role for CD18 phosphorylation in the activation of CR3 for phagocytosis is consistent with these data.

Alkaloids↗
PubMed1991

Autoantibody to heat-shock protein 90 can mediate protection against systemic candidosis.

Epitope mapping shows that patients recovering from systemic infection with Candida albicans produce antibodies against both fungal-specific and conserved epitopes of the heat-shock protein (hsp) 90. In a mouse model of systemic candidosis, mortality was halved by prior administration of sera from two infected patients containing antibodies to hsp 90. One of these patients had no other candidal antibodies detectable on immunoblotting. The protective effect was mediated by the immunoglobulin fraction of the immune serum. It was not observed with a normal human serum. A mouse monoclonal antibody raised against one of the conserved peptide epitopes suggested that an autoantibody to hsp 90 could mediate protection against systemic candidosis in the animal model.

Animals↗
PubMed1986

Effects of erythromycin and ciprofloxacin on chronic fecal excretion of Campylobacter species in marmosets.

Ciprofloxacin was compared with erythromycin for the eradication of Campylobacter species that were chronically excreted in the stools of marmosets (Saguinus labiatus labiatus, Saguinus fuscicollis nigrifrons, and Saguinus fuscicollis illigeri). Stool cultures were negative within 48 h of the beginning of treatment with either agent. Within 10 days after the end of therapy, however, Campylobacter species were again isolated from the stools of six animals that had received erythromycin. During an 8-week follow-up period, no animal that had received ciprofloxacin relapsed. High levels of ciprofloxacin in the stool (mean, 49.2 micrograms/g) possibly contributed to the efficacy of this agent.

Animals↗