Levan production by a strain of Rothia: activation of complement resulting in cytotoxicity for human gingival cells.

An extracellular polysaccharide identified as a levan has been isolated from Rothia dentocariosa, strain 477 serotype 2. The levan produced by strain 477 has been found to activate the complement cascade in the absence of specific antibodies. This activation was found to be cytotoxic for human gingival cells in tissue culture.

A simple ultrasound method to characterize in vitro plaque inhibition activity.

A method employing ultrasound vibration for evaluating in vitro plaque derived from Streptococcus mutans was developed. It successfully detected small changes in the cohesive/adhesive characteristics of deposits briefly exposed to several antibacterials and "antiadherents". Increased structural fragility and diminished plaque growth were generally associated with the antibacterials.

Blastogenic response of human lymphocytes to antigens of Rothia dentocariosa.

Peripheral blood lymphocytes were isolated from 20 individuals with varying degrees of periodontal health and classified as either normal, having acute gingivitis (GV), or chronic periodontitis (PD). Crude cell wall and cytoplasmic antigens were derived from Rothia dentocariosa (RD), were applied to lymphocyte microcultures, and subjected to radioactive thymidine; the resulting lymphocyte blastogenesis (LB) was surveyed with a scintillation counter. All three groups displayed statistically similar levels of stimulation (F = 0.71), demonstrating that crude antigens of RD are not appreciably active in vitro studies of cell-mediated immunity (CMI), as measured by LB.

Extracellular iodophilic polysaccharide synthesized by Neisseria in human dental plaque.

Dental plaque collected from the label aspect of the anterior dentition of children harbored Neisseria that synthesized an extracellular iodophilic polysaccharide (EIP) from sucrose. Gas chromatograms of fully-acetylated EIP derivatives indicated that glucose (97%) and galactose (3%) were the only monosaccharide constituents present. The characterization of the partially-methylated alditol acetate (PMAA) derivatives of EIP indicated that it was primarily a linear 1,4 glucan (75.5%), with some 1,6 glucan (8.4%). The relative linearity of EIP (96.6%) as compared to that of amylose and glycogen was confirmed by spectrophotometric absorption studies.

Parasitization of humans in West Virginia by Ixodes cookei (Acari: Ixodidae), a potential vector of Lyme borreliosis.

In 32 collections, two larvae, 33 nymphs, and one adult female Ixodes cookei Packard were collected from humans in West Virginia from August 1987 to May 1990. Most were attached. The ticks were found in 14 counties and were the most abundant Ixodes found biting humans. One nymphal I. cookei was removed from the left axilla of a 39-yr-old woman who lives and works in Monongalia and Marion counties, W. Va. The bite was the center of an expanding erythematous lesion reaching 4 cm in diameter, clearing centrally, and typical of erythema migrans. This association and the near absence of Ixodes dammini Spielman, Clifford, Piesman & Corwin from the state suggests the possibility that I. cookei may be an important vector of Lyme borreliosis in West Virginia. In five separate collections, five nymphal Ixodes dentatus Marx were removed from humans in four counties, implicating this species as a potential minor vector of Lyme borreliosis in West Virginia.

Migration and chemiluminescence of polymorphonuclear cells and monocytes to Bacteroides sonicates.

Recent investigations have demonstrated that various preparations obtained from representatives of the genus Bacteroides are poorly phagocytized by polymorphonuclear cells (PMN) and macrophages. Crude cell sonicates derived from Bacteroides have been examined for their ability to inhibit migration of PMN and monocytes using a modified migration under agarose in vitro assay. B. gingivalis and B. intermedius were found to be inhibitors of such migration while B. asaccharolyticus did not share this property (P less than 0.005). In addition, B. intermedius sonicates were found to inhibit PMN chemiluminescence to known stimulants (P less than 0.001). These data were not found to result from direct sonicate cytotoxicity and therefore lend additional support to the etiologic importance of specific Bacteroides strains in the pathogenesis of acute and chronic dentoalveolar infections.

Biochemical and biophysical properties of hyphomicrobium bacteriophage hyphi30.

Hyphomicrobium bacteriophage Hyphi30 and its nucleic acid were studied to determine some of their biochemical and biophysical properties. The molecular weight of the phage is 55.4 x 10(6), and its buoyant density is 1.508 g/ml. The nucleic acid of Hyphi30 is linear, double-stranded DNA with a molecular weight of 29.7 x 10(6). The guanine-plus-cytosine content of the DNA was 62% as determined from its melting temperature and buoyant density.

Cytotoxic and immunostimulatory effects of Bacteroides cell products.

The etiologic role of Bacteroides in both periodontal and periapical infections has been well documented, with current interest focusing on the specific pathogenic mechanisms involved. The effects of cell fractions derived from Bacteroides gingivalis (BG), Bacteroides intermedius (BI), and Bacteroides asaccharolyticus (BA) have been studied in vitro through: an assessment of the direct cytotoxic effects on human gingival fibroblasts using a tetrazolium dye reduction assay, an evaluation of murine lymphocyte stimulation and interleukin-1 release, and the induction of human lymphocyte-mediated cytotoxicity. Both BG and BI stimulated interleukin-1 release (P less than 0.001), while BA, a nonoral organism, was not significantly active in this respect. Only BG sonicates were able to induce lymphocyte-mediated cytotoxicity (P less than 0.005). All three Bacteroides species demonstrated direct cytotoxic effects on cultured gingival fibroblasts, and these effects were related to the relative protein content and endotoxin activity of the sonicate preparations for each organism. These data show that BG and BI possess factors which may enhance their virulence through activities not shared with BA.

Levels of bacteria, fungi, and endotoxin in bulk and aerosolized corn silage.

Three samples of silage taken from the surface of a silo and from depths of 20 and 45 cm in the silo were studied for identification of the potential agents causing symptoms of organic dust toxic syndrome. The samples were examined by dilution plating before and after aerosolization in an acoustical dust generator. Aerosol samples were collected by liquid impinger and filter cassettes. The samples were examined for total aerobic bacteria, anaerobic bacteria, gram-negative bacteria, lactobacilli, listeriae, thermophilic actinomycetes, fungi, and endotoxin. Very high levels of total aerobic bacteria and fungi were found in the surface sample (up to 10(9) CFU/g in the bulk sample and up to 10(9) CFU/m3 after aerosolization), whereas the corresponding values from the deepest site were 100 to 50,000 times lower. Aspergillus fumigatus predominated among the fungi, whereas Bacillus and gram-negative organisms (Pseudomonas, Alcaligenes, Citrobacter, and Klebsiella species) prevailed among bacteria. Thermophilic actinomycetes occurred in numbers up to 10(7) CFU/g in the bulk samples, whereas anaerobic bacteria, lactobacilli, and listeriae were only few or absent. The concentration of endotoxin was high in the surface sample (up to 211.4 Endotoxin Units/mg) and about 200-fold lower in the sample from the deepest site. The results show that contact with dust from the surface of silage carries the risk of exposure to high concentrations of microorganisms, of which A. fumigatus and endotoxin-producing bacteria are the most probable disease agents.