The reaction of salivary substances with bacteria

Abstract

Abstract. Reactions between selected strains of oral streptococci and saliva were studied spectrophotometrically. The curves of absorbance (700 nm) versus those of time were sigmoidal for aggregating saliva‐bacteria mixtures. When the logarithm of the ratio of the change in absorbance to the remaining absorbance was plotted against the reaction time, straight lines were obtained. At a fixed concentration of bacteria, the slope of these lines for a series of dilutions of a selected saliva sample was a parabolic function of the volume of saliva in the reaction mixtures. A model for the aggregation reaction was developed which explained the shape of these parabolic curves. The parameters of the model can be calculated from the experimental data and can be used to estimate the concentration of aggregation‐inducing substances in undiluted saliva. A method for calculating the specific rate constant for the binding of free cells to aggregates was developed. This rate constant is a characteristic feature of a given aggregation reaction and can, in principle, be used to distinguish between aggregation‐inducing substances of different molecular structures.

Interactions of surfactant protein D with bacterial lipopolysaccharides. Surfactant protein D is an Escherichia coli-binding protein in bronchoalveolar lavage.

“…coli, presumably via N-acetyl-glucosamine and/or L-glycero-D-manno-heptose residues associated with core oligosaccharides. In other studies, Kuhlman et al (13) showed that serum MBP binds to mannose-rich 0-poly-+ Adsorbed BAL saccharides on the surface ofwild-type Salmonella montevideo ;orbance 1.0 has been extensively studied in the context of oral microbes BAL or with 3 and saliva (22,31), and there appear to be several types of affinity chrosalivary proteins that can mediate bacterial agglutination. e was adjusted Among these is a group of nonimmunoglobulin, nonmucous ubations were salivary agglutinins with conglutinin-like activity (32,33 (3) and are also consistent with protein biochemical studies that indie calcium-in-cate that SP-D is assembled as tetramers of trimers, similar to )served sugar bovine conglutinin (2,4).…”

“…The time course of macroscopic bacterial agglutination was monitored using a spectrophotometric sedimentation assay modified from Ericson et al (22). Stock solutions of bacteria were prepared in HBS (OD700nm = 1.0).…”

Differential adhesion of Pseudomonas aeruginosa to human respiratory epithelial cells in primary culture.

“…Preliminary results from our laboratory suggest that mucin may be involved in the observed P. aeruginosa aggregation, as shown by ongoing immunocytochemical studies using a monoclonal antibody 17 B. developed using purified large molecular weight macromolecules of rhesus monkey tracheal secretion as immunogen (24,25), kindly supplied by Dr. R. Wu (California Primate Research Center, University of California). Mucin-like glycoproteins present in saliva are known to induce the aggregation oforal bacteria (26,27). Bacterial aggregation in the respiratory tract may be of great in vivo significance since large aggregates are supposed to be cleared more easily by the mucociliary transport than individual organisms.…”

Surfactant Protein D-Mediated Aggregation ofPneumocystis cariniiImpairs Phagocytosis by Alveolar Macrophages

“…To remove EDTA and glutathione prior to the assay, P. carinii suspensions were twice centrifuged at 1,000 ϫ g for 10 min at 4°C, resuspended with TBS (50 mM Tris HCl-150 mM NaCl [pH 7.4]), and adjusted to a concentration of 7.5 ϫ 10 6 P. carinii organisms per ml. The subsequent aggregation of P. carinii was quantified by using a modification of the spectrophotometric sedimentation assay of Ericson and coworkers (14,28). The time course of macroscopic P. carinii agglutination was monitored using a spectrophotometer (model DU-74; Beckman Coulter Inc., Fullerton, Calif.) at a 700-nm wavelength (measuring optical density at 700 nm [OD 700 ]).…”