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B F Hammond

Publications and source records attributed to B F Hammond.

At least 37 records · Page 2Linked to original sources
PubMed1980

Biological and chemical characterization of endotoxin from Capnocytophaga sputigena.

An endotoxin was isolated from Capnocytophaga sputigena strain 4 by a modification of the hot phenol-water method. The extraction procedure yielded a lipopolysaccharide which accounted for approximately 1.5% of the dry weight of the cells. The material was composed of 18.6% lipid (as C(15) fatty acid), 46.5% neutral sugar including 9.6% hexose, 18.3% 6-deoxy sugar, 1.0% 2-keto-3-deoxy sugar, and 4.8% heptose. Hexosamine, protein, and phosphorus were found in quantities amounting to 9.0, 2.9, and 2.0% of the dry weight, respectively. No pentose or nucleic acid was detected. Acid hydrolysis resulted in the release of the constituent sugars and the formation of an insoluble precipitate. The lipopolysaccharide was tested for numerous biological activities characteristic of endotoxins. The pyrogenicity was relatively low; the fever index 40 was 17 mug, and 10 mug was required to give the characteristic biphasic fever response. The toxicity of the extract was very low, with a 50% chicken embryo lethal dose of 15.6 mug and a 50% mouse embryo lethal dose of greater than 8 mg. Similarly, the C. sputigena endotoxin had modest effects on leukocytes when compared with endotoxin standards from other organisms. The extract exhibited little or no mitogenicity when tested on mouse spleen lymphocytes. It was not toxic to human peripheral polymorphonuclear leukocytes and caused the release of only a small (13%) portion of lysosomal enzymes. Although the C. sputigena lipopolysaccharide caused significant activation of mouse peritoneal macrophages, the dose required was twice that of an Escherichia coli endotoxic standard. However, the Limulus amoebocyte lysate clotting activity of the lipopolysaccharide was comparable to that of an Serratia marcescens lipopolysaccharide standard, and passive hemagglutination tests revealed that 1 mug of the lipopolysaccharide was capable of sensitizing 1 ml of a 2% sheep erythrocyte suspension for agglutination with an antiserum prepared against C. sputigena whole cells.

Animals↗
PubMed1980

Detection of a fibroblast proliferation inhibitory factor from Capnocytophaga sputigena.

The addition of a sonic extract of Capnocytophaga sputigena to the culture fluid to human fibroblasts resulted in an inhibition of cell proliferation. The inhibition was dose-related (200 micrograms/ml caused a 90% inhibition, and 1,000 micrograms/ml caused a complete cessation of growth). The growth inhibition was not due to alterations in culture medium, pH or ionic strength, or to the effects of the C. sputigena lipopolysaccharide.

Cell Division↗
PubMed1979

Capnocytophaga: new genus of gram-negative gliding bacteria. III. Physiological characterization.

Sixty-eight strains of capnophilic fusiform Gram-negative rods from the human oral cavity were subjected to extensive physiologic characterization, tested for susceptibility to various antibiotics, and the mol-percent guanine plus cytosine of each isolate determined. The characteristics of the isolates were compared with 10 fresh and 2 stock isolates of Fusobacterium nucleatum. The isolates clearly differed from the Fusobacterium species on the basis of mol-percent guanine plus cytosine, end products, growth in a capnophilic environment and fermentation of carbohydrates. All of the gliding isolates required CO2 and formed acetate and succinate, but not H2S, indole or acetylmethylcarbinol. All fermented glucose, sucrose, maltose and mannose. The organisms may be differentiated on the basis of fermentation of additional carbohydrates, hydrolysis of polymers and reduction nitrate. Three species are proposed: Capnocytophaga ochracea, Capnocytophaga sputigena and Capnocytophaga gingivalis. Ten isolates did not fit into the proposed species.

Adult↗
PubMed1979

Group and type antigens of Capnocytophaga.

Group-specific and type-specific antigens have been identified and purified from sonic extracts of Capnocytophaga. The group-specific antigen, which was purified by affinity chromatography, was found to be identical to an antigen present in all 26 strains tested. The antigen is sensitive to trypsin, sodium dodecyl sulfate and heat labile, and composed predominantly (55%) of protein. The type-specific antigen, which was obtained by preparative immunoelectrophoresis, was found to be present in only 3 of the 26 strains tested. This antigen was resistant to heat, trypsin, and sodium dodecyl sulfate and was primarily composed of carbohydrate (47% phenol-sulfuric acid-positive material, 8% amino sugar). Agglutination and fluorescent antibody data suggest that both the group- and type-specific antigens reside on the cell surface.

Antigens, Bacterial↗
PubMed1979

Interaction of inflammatory cells and oral microorganisms. VIII. Detection of leukotoxic activity of a plaque-derived gram-negative microorganism.

In the present study we identified a gram-negative anaerobic rod referred to as Y4 which was cytotoxic for human polymorphonuclear leukocytes. Y4 was isolated from dental plaque of a patient with juvenile periodontitis and presented most of the taxonomic characteristics of Actinobacillus species. Under experimental conditions, viable Y4 were cytotoxic for human peripheral blood polymorphonuclear leukocytes in serum-free cultures. Cytotoxicity was dependent on bacterial concentrations and was enhanced in the presence of a fresh or heat-inactivated (56 degrees C, 30 min) autologous serum. Leukotoxicity was independent of phagocytosis. Y4 leukotoxic effect was abolished when bacteria were heat treated (56 degrees C, 30 min) or when incubations were carried out at 4 degrees C instead of at 37 degrees C. The leukotoxicity was monitored by electron microscopy and biochemically by measuring lactate dehydrogenase indicator of cell viability. No cytotoxic effects of Y4 on human mononuclear cells, chicken fibroblasts, or mouse macrophages were detected under the conditions studied. Polymorphonuclear leukocytes may play an important role in the host defense against bacteria in periodontal disease. The cytotoxic effect of Y4 for polymorphonuclear leukocytes presented in this study is the first report of a direct offensive microbial vector in a plaque-derived microorganism and may prove to be relevant in the pathogenesis of juvenile periodontitis.

Dental Plaque↗
PubMed1979

Extraction and partial characterization of a leukotoxin from a plaque-derived Gram-negative microorganism.

The plaque-derived gram-negative microorganism Y4 identified as a member of the genus Actinobacillus, was tested for a soluble cytotoxic factor(s). Sonication or incubation of viable Y4 microorganisms in distilled water or normal human serum resulted in liberation of a soluble material which was cytotoxic in vitro for human polymorphonuclear leukocytes (PMNs). The Y4 soluble sonic extract was also cytotoxic to human peripheral blood monocytes. However, human lymphocytes, platelets, and fibroblasts, as well as rabbit, rat, and mouse leukocytes and chicken embryo fibroblasts, were not killed by exposure to the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. No hemolytic activity was detected in the Y4 sonic extract. Consequently, the factor(s) in the Y4 sonic extract was referred to as Y4 leukotoxin. The Y4 leukotoxin was inactive at 4 degrees C, heat sensitive (56 degrees C, 30 min), and inactivated by proteases. The cytotoxic effect of Y4 leukotoxin on PMNs was dose, time, and temperature dependent. The leukotoxin did not bind to viable PMNs at 4 degrees C but did bind to dead PMN membrane components at both 4 and 37 degrees C. The addition of bovine serum albumin (51 mg/ml) to PMN-Y4 leukotoxin cultures inhibited the release of lactate dehydrogenase from the PMNs, but did not prevent the death of the cells as indicated by electron microscopy. Lysosomal markers were released in parallel to the cytoplasmic enzyme lactate dehydrogenase from Y4 leukotoxin-treated PMNs. The addition of 0.02 M ethylenedinitrilotetraacetic acid to these cultures inhibited release of lysosomal markers but enhanced the release of lactate dehydrogenase. These results suggested that a soluble leukotoxin with specificity for only human PMNs and monocytes can be liberated from viable Y4. What role this leukotoxin plays in the pathogenicity of the Y4 microorganism is not yet known. However, this leukotoxin is one of the first materials from a plaque-derived microorganism with a potential role in the pathogenesis of juvenile periodontitis.

Actinobacillus↗
PubMed1978

Interaction of inflammatory cells and oral microorganisms. VII. In vitro polymorphonuclear responses to viable bacteria and to subcellular components of avirulent and virulent strains of Actinomyces viscosus.

Both virulent (V) and avirulent (AV) strains of Actinomyces viscosus T14 are capable of colonizing the oral cavity of gnotobiotic rats, but only T14-V causes destructive periodontal disease. The basis for this difference in in vivo pathogenicity has not been adequately defined. In the present study we compared the capacities of T14-AV and T14-V to provoke in vitro extracellular release of lysosomal constituents from human polymorphonuclear leukocytes (PMNs). In serum-free cultures, viable T14-V but not T14-AV stimulated discharge of PMN lysosomes. The release response was correlated with PMN phagocytic activity; thus, PMNs readily ingested T14-V but not T14-AV. To explain these differences in PMN-bacteria interactions, subcellular fractions of T14-AV or T14-V were incubated with PMNs. A crude, insoluble sonic extract derived from T14-V caused PMN lysosome release, but a similar fraction from T14-AV was inactive. However, following extensive washing and treatment with deoxyribonuclease or sodium dodecyl sulfate, cell wall fractions of T14-AV stimulated lysosome release. These procedures apparently removed an extracellular polysaccharide slime which is synthesized by T14-AV but not by T14-V. There was a significant reduction in the capacities of viable T14-V or cell wall fractions of T14-V or T14-AV to provoke PMN lysosome release when these agents were preincubated with a slime material isolated from T14-AV. This inhibitory influence of slime was overcome by the addition of fresh or heated (56 degrees C, 30 min) serum to the PMN-bacteria cultures. The data suggest a relationship between the abilities of the avirulent and virulent strains of A. viscosus T14 to act as periodontal pathogens in vivo and to serve as stimuli for PMN lysosome release in vitro.

Actinomyces↗
PubMed1978

Role of colonization in the virulence of Actinomyces viscosus strains T14-Vi and T14-Av.

Germfree rats fed a high-sucrose diet were inoculated with Actinomyces viscosus strain T14-Vi (virulent) or T14-Av (avirulent). The mean recovery of strain T14-Vi from six extracted finely ground molars of rats sacrificed after 90 days was 1.1 x 10(8) colony-forming units (CFU). The mean recovery of strain T14-Av was 5.7 x 10(7) CFU, which was significantly less. Strain T14-Vi caused severe alveolar bone loss, but only minimal bone loss occurred in rats infected with strain T14-Av. Scanning electron microscopy of teeth of germfree rats revealed that strain T14-Vi colonized in the fissures as well as on tooth surface areas near the gingiva; strain T14-Av also colonized in fissures but was unable to colonize the teeth near the gingiva. In studies with conventional rats fed a high-sucrose diet, streptomycin-resistant strain T14-Vi colonized on the teeth of all rats inoculated with in the order of 10(8) or 10(7) CFU and on the teeth of about half of the rats inoculated with 10(6) or 10(5) CFU. In contrast, streptomycin-resistant strain T14-Av could not be detected on the teeth of any of the rats in groups similarly inoculated. In vitro "resting" cells of both strains suspended in conventional or germfree rat saliva survived to comparable degrees. [(3)H]thymidine-labeled T14-Vi cells adhered well to hydroxyapatite (HA) beads and to HA beads pretreated with saliva obtained from germfree or conventional rats. In contrast, T14-Av cells adhered less well than did T14-Vi cells to HA, whereas their adherence to saliva-coated HA was negligible. Transmission electron microscopy of negatively stained T14-Vi and T14-Av cells repeatedly passed in 1% phosphotungstic acid revealed fibrils on cells of both strains. T14-Av cells were covered by large amounts of extracellular material which was presumably heteropolysaccharide; little extracellular material was present on the surface of T14-Vi cells. T14-Vi cells had a relatively low affinity for the heteropolysaccharide synthesized by strain T14-Av. Other evidence also suggested that this polysaccharide had a relatively low affinity for saliva-coated HA. Collectively, the evidence indicates that the difference in periodontopathic potential between strains T14-Vi and T14-Av results from their different abilities to colonize teeth. This difference is probably due to the lower adherence of T14-Av cells to teeth rather than to their ability to grow in the mouth. The low affinity of T14-Av cells for tooth surfaces may be due, in part, to the presence of large amounts of cell-surface-associated polysaccharide.

Actinomyces↗
PubMed1976

Antigens and surface components associated with virulence of Actinomyces viscosus.

We have isolated a specific cell wall antigen of high molecular weight which appears to be unique to virulent strains of A viscosus and A naeslundii. The antigen is composed of two parts: a polysaccharide moiety containing 6-DOT as the major sugar and determinant of serologic specificity, and a small peptide bearing some resemblance to the peptidoglycan. Other data indicate a positive correlation between the presence of this antigen and an extrachromosomal piece of DNA having most of the properties of a bacterial plasmid. The specific function of the 6-DOT antigen in disease production is not known, but its clear association with virulent strains suggests the possibility of monitoring specific populations of oral actinomycetes.

Actinomyces↗
PubMed1974

Extracellular polysaccharides of Actinomyces viscosus.

Polysaccharide(s) have been isolated from supernatants of broth cultures of Actinomyces viscosus, strain T6. The organism produces significant quantities (2 mg/mg of cell [dry weight], 108 mg/liter) of this polysaccharide in the absence of sucrose. Chemical analysis indicated that N-acetylglucosamine (62%) was the major component; galactose (7%), glucose (4%), uronic acid (3%), and smaller amounts of glycerol, rhamnose, arabinose, and xylose were also present. The polysaccharide(s) is only slightly soluble in aqueous solutions. Although further purification of the polysaccharides will be necessary before definitive chemical and structural studies, the formation of extracellular polysaccharides is significant because it offers a possible explanation for plaque formation by these organisms.

Actinomyces↗