Effect of crevicular fluid and lysosomal enzymes on the adherence of streptococci and bacteroides to hydroxyapatite

Samples of hydroxyapatite (HA) beads smaller than 1 mg were coated with 10 microliter of either saliva, serum, or human crevicular fluid before being added to a suspension of Streptococcus sanguis or Bacteroides gingivalis. In some assays, preparations of a granular fraction, elastase, or cathepsin G from human leukocytes were used to coat HA or to treat saliva-coated HA (SHA) before mixing with bacteria. The number of cells adhering to the beads was then counted under a scanning electron microscope by a standardized procedure. More cells were found to adhere to SHA in this assay than in the conventional large-scale assay. Human crevicular fluid, even when diluted up to three times, completely inhibited the adherence of S. sanguis to HA. A 100% inhibition of S. sanguis adherence was also observed when HA was coated with the granular fraction of leukocytes, and a 65% inhibition observed when SHA was treated with the enzyme preparation. When used to coat HA, elastase and cathepsin G reduced the adherence of S. sanguis by 30 and 50%, respectively. The binding of S. sanguis to elastase- or cathepsin G-treated SHA was also reduced. B. gingivalis 33277 was found to adhere in high numbers to SHA. Coating HA with crevicular fluid or with the lysosomal enzyme preparation had a limited negative effect. We postulate that crevicular fluid prevents the adherence of S. sanguis by virtue of either its enzyme content or its albumin content or both.

Identification and preliminary characterization of a Streptococcus sanguis fibrillar glycoprotein

Cell surface fibrils could be released from Streptococcus sanguis 12 but not from strains 12na or N by freeze-thawing followed by brief homogenization. Fibrils were isolated from the homogenate by ultracentrifugation or ammonium sulfate precipitation. Electron microscopy demonstrated the presence of dense masses of aggregated fibrils in these preparations. Under nondenaturing conditions, no proteins were seen in polyacrylamide gel electrophoresis (PAGE). Sodium dodecyl sulfate (SDS)-PAGE analysis revealed a single band stained with Coomassie blue and periodic acid Schiff stain with a molecular weight in excess of 300,000. The protein has been given the name long-fibril protein (LFP). The molecule was susceptible to digestion with subtilisin, pronase, papain, and trypsin, but was unaffected by chymotrypsin or muramidases. Attempts to dissociate the protein into smaller subunits with urea, guanidine, sodium thiocyanate, and HCl were unsuccessful. Gel filtration on a column of Sephacryl S-400 in the presence of 2% SDS resulted in elution of the protein at the void volume. Antibody raised against the LFP excised from an SDS-PAGE gel reacted with long fibrils on the surface of strain 12 and with isolated fibrils by an immunogold labeling technique. Monoclonal antibody reactive with LFP in SDS-PAGE also reacted with fibrils present on the cell. Antisera raised against the fibrils inhibited adherence to saliva-coated hydroxyapatite.

Eczéma séborrhéique et psoriasis chez le nourrisson: étude comparative morphologique et cinétique

Seborrhoeic dermatitis, psoriasis and atopic dermatitis in infants were studied morphologically and autoradiographically on skin biopsies. A similar picture with an increased germinative cell population and accelerated cell turnover has been found in psoriasis and seborrhoeic dermatitis. These features may suggest a relationship between both diseases.

Biochemical and immunological differences between hydrophobic and hydrophilic strains of Streptococcus mutans

Hydrophobic strains of Streptococcus mutans were compared with paired variants showing reduced hydrophobicity. Extracts of hydrophobic cells contained a number of high-molecular-weight proteins which were not present on cells with decreased hydrophobicity. The proteins were found in purified cell walls, suggesting that they are located on the bacterial surface. Trypsin treatment of whole cells destroyed the proteins and reduced the hydrophobicity. Chemical analysis did not reveal any marked differences in the proportion of cell wall constituents. The amino acid compositions and lipoteichoic acid contents of hydrophobic and hydrophilic cell walls were similar. Culture supernatants from the hydrophilic variants contained high-molecular-weight proteins similar to those extracted from the cell walls of the hydrophobic parent strains, indicating that the variants were impaired in their ability to incorporate the hydrophobicity-associated proteins into the cell wall. The dominant protein had a molecular weight of 190,000, similar to that of antigen I/II (B) of S. mutans.

[Atopy and dermatophyte infection in children]

The atopic chronic dermatophytosis syndrome is uncommon in children. Clinical and immunological characteristics are reviewed. The infecting fungus is Trichophyton rubrum, occasionally Trichophyton interdigitale.

Characterization of cellular infiltrates in skin lesions of atopic eczema by means of monoclonal antibodies

Frozen skin biopsies from 3 acute and 3 chronic lesions of atopic dermatitis were examined by means of various ortho-monoclonal antibodies (OKT3, 4] not equal to----4, OKT6, OKT8; OKIa and OKM1) in an indirect immunofluorescence technique. The results show that both T helper (T4) and T suppressor cytotoxic (T8) lymphocytes are present in the inflammatory infiltration which predominantly contained Ia mononuclear cells. Despite the absence of double staining procedure, the observations suggest that T4 cells predominate over T8 cells in the acute lesions whereas the reverse tendency is noted in the chronic lesions. T8 cells are found mainly in the superficial dermis or even in the epidermis; by contrast, T4 cells tend to be more deeply located in the dermis. The lesions are characterized by a dramatic increase in the number of Langerhans cells (OKT6, OKIa+) that are found not only in the epidermis but also in the dermis.

Contact sensitivity to rubber additives in Belgium

The frequency of positive patch tests to rubber additives in Belgium is recorded. Allergy due to rubber protective gloves represents 41% of the overall sensitivity to rubber.