PubMed Health⌕ Search

Biomedical subjects

R E Baughn

Publications and source records attributed to R E Baughn.

83 records · Page 5Linked to original sources
PubMed1977

Effect of sensitization with Propionibacterium acnes on the growth of Listeria monocytogenes and Treponema pallidum in rabbits.

Sensitization of rabbits with Propionibacterium acnes, a nonspecific stimulant of the reticuloendothelial system, was investigated as a means of enhancing resistance to Treponema pallidum. A single i.v. dose of P. acnes given 3 or 7 days before challenge with Listeria monocytogenes was capable of suppressing the growth of the heterologous organism, whereas a single i.v. dose 24 hr or 14 days before challenge was not. Reactivation via i.v. elicitation with P. acnes 14 days after sensitization (1 day before challenge) caused significant suppression of listerial growth in the major organs 30 hr after i.v. challenge. A series of similar experiments was designed with T. pallidum as the challenge organism. Sensitization and repetitive elicitation with P. acnes did not change the time of appearance or progression of syphilitic chancres after i.v or i.d. challenge. Injection of P. acnes into sites of intradermal T. pallidum challenge in previously sensitized rabbits also failed to alter the evolution of syphilitic lesions. These results suggest that macrophage activation does not alter the host's ability to suppress the growth of T. pallidum.

Animals↗
PubMed1977

Enhancement of carrier-mediated transport after immunologic activation of peritoneal macrophages.

Immunologically activated peritoneal macrophages from inbred mice and Hartley strain guinea pigs demonstrate a markedly greater than normal transport of 2-deoxy-D-glucose and L-leucine. The degree of nutrilite transport enhancement was greatest when animals were injected with the appropriate eliciting antigens before harvesting and also, if antigen was included in the tissue culture medium during the initial hours of in vitro culture. Enhanced hexose and amino acid uptake could also be achieved by exposure of macrophages from nonimmunized animals for 48 hr to supernatants of sensitized splenic lymphocyte cultures incubated with specific antigens. The animal systems in which this phenomenon was observed included CBA/J and C57BL/6J mice immunized with Staphylococcus aureus or sub-lethal doses of Listeria monocytogens, and the Hartley strain, albino guinea pig immunized with S. aureus or BCG. In all cases, immunization resulted in a state of delayed hypersensitivity as measured by skin testing or footpad swelling. Splenic cell supernatants contained lymphokines as detected by the presence of macrophage inhibitory factor (MIF), and by the supernatants' capacity to stimulate incorporation of 14C-glucosamine by macrophages in vitro. No increase of glucose or leucine transport by macrophages was observed in the absence of appropriate antigen stimulation in vivo or in vitro. We previously showed that a phagocytic stimulus results in a significant increase in hexose transport by normal macrophages; leucine transport by these same cells was unaltered after phagocytosis. In contrast, immunologically activated macrophages do not transport measurably more 2-deoxy-C-glucose after particle ingestion; activation or the phagocytic stimulus enhance 2-deoxy-C-glucose uptake to approximately the same extent. Analysis of nutrilite transport kinetics revealed that immunologic activation of macrophages increases the initial velocity (V1) and Vmax but does not change the Km values of hexose or amino acid transport. The kinetics of transport by the immunologically activated macrophages do not change measurably after phagocytosis. We conclude that either immunological activation or phagocytosis results in augmented 2-deoxy-D-glucose transport via identical or related mechanisms and that transport of the sugar can't be increased above that level induced by either event. The reasons why immunologic activation increases both glucose and leucine transport but phagocytosis increases only the former are not yet understood.

Animals↗
PubMed1975

Nonspecific resistance to Listeria monocytogenes in mice infected and elicited with Staphylococcus aureus.

Normal mice and mice displaying delayed hypersensitivity to Staphylococcus aureus were challenged with a lethal dose of Listeria monocytogenes. Nonspecific antimicrobial activity was assessed by inhibition of bacterial growth in the spleen and by increased survival rates. Administration of specific staphylococcal antigen prior to challenge was a prerequisite for the induction of nonspecific resistance. Both the time of administering eliciting antigen and the route were important consideration for evoking the response. Similar responses were seen in 3 strains of inbred mice following immunization with both encapsulated and nonencapsulated staphylococci. Although enhanced resistance as measured by viable counts in the spleens was achieved after 2 injections, protection as measured by survival required 4 injections of S. aureus followed by elicitation with staphylococcal antigens. Nonspecific resistance could be detected as late as 9 weeks after the disappearance of delayed hypersensitivity.

Animals↗
PubMed1966

Antigenic structure of Brucella suis spheroplasts.

Baughn, Robert E. (University of Tennessee, Memphis), and Bob A. Freeman. Antigenic structure of Brucella suis spheroplasts. J. Bacteriol. 92:1298-1303. 1966.-Immunoelectrophoresis was used to differentiate between the antigenic mosaics of normal cells of Brucella suis and of spheroplasts prepared by treatment with penicillin, glycine, and a combination of these agents. Smooth cells possessed at least 13 antigens, 10 of which were precipitated with homologous antiserum. Three additional antigens were visualized by reaction with spheroplast antisera. Spheroplasts induced with glycine were the least complex, with only six antigens. Penicillin-glycine spheroplasts were similar, but possessed one additional antigen. Penicillin spheroplasts were the most complex, with eight antigens. Although there appeared to be quantitative differences between the antigens of spheroplasts and normal cells, no completely new antigens were detected in spheroplasts. Serum absorption studies indicated that four antigens were associated with the surface of normal B. suis, none of which occurred in spheroplasts.

Antigens↗
PubMedDate not supplied

Role of fibronectin in the pathogenesis of syphilis.

In recent years studies concerned with the attachment of Treponema pallidum to host cells have focused on the possible, role of fibronectin in mediation of this event. Although our understanding of in vitro fibronectin-T. pallidum interactions has increased markedly, considerable controversy exists concerning not only the kinetics of binding but whether fibronectin is the only matrix protein involved in attachment. Moreover, a unifying hypothesis concerned with the role of fibronectin in the pathogenesis of syphilis cannot be limited solely to early events. Further characterization of fibronectin-T. pallidum interactions must also take into consideration that the natural infection, characterized by distinct stages, is accompanied by immunologic responses that undoubtedly impact on those cellular interactions.

Bacterial Adhesion↗
PubMedDate not supplied

Immune complexes in experimental syphilis: a methodologic evaluation.

Sustained antigenic stimulation following intravenous infection of rabbits with Treponema pallidum results in antibody responses and the formation of immune complexes. Complexes in greater than 300 sera from normal rabbits and from animals with experimental syphilis were measured by Raji cell and polyethylene glycol-complement consumption assays. Profound increases in both the incidence and levels of immune complexes were seen between the third and seventh weeks of infection. Single radial immunodiffusion studies revealed moderate increases in immunoglobulin levels and depression of C3 levels during the third and fourth weeks of infection. Penicillin treatment was followed by normalization of C3 levels and clearance of immune complexes. Lower levels of complexes in the sera of intradermally infected rabbits and the absence of immune complexes in intratesticularly infected animals suggest that immune complexes in the circulation may be related to the extent and severity of cutaneous involvement.

Animals↗