Biomedical subjects

D C Straus

Publications and source records attributed to D C Straus.

79 records · Page 5Linked to original sources

PubMed1976

Characterization of group A streptococcal M-proteins purified by two methods.

Ten different group A streptococcal M-protein preparations purified by trichloroacetic acid precipitation and three M-protein preparations purified by cellulose chromatography were examined by SDS and polyacrylamide gel electrophoresis, and analyzed for amino acid composition and N-terminal amino acids. Fingerprinting (both tryptic and chymotryptic) was performed on the cellulose purified preparations of M1, M12, and M29 proteins which showed these proteins to be structurally related. Trypsin produced mas with 37 to 42 peptides, whereas chymotrypsin digestion resulted in 8 to 12 peptides, depending on the M-type. Sequencing was performed on the M12 protein and tentative identification of nine N-terminal amino acids made. Molecular weights of the cellulose and TCA-purified M-proteins were determined by SDS gel electrophoresis and chromatography on G-200 Sephadex, with comparable results, indicating followed the patterns established for M-proteins, with high concentrations of lysine, aspartic acid, glutamic acid, alanine, and leucine. All 10 proteins had L-alanine as their N-terminal amino acid. Evidence for a one way cross-reaction between type 1 and type 29 streptococci was also found.

Amino Acid Sequence↗

PubMed1974

Simplified method for the purification of group A streptococcal M-proteins: solution of the multiple banding problem.

A simple and rapid procedure for the isolation in high yield (about a 30% recovery based on the total 30 to 60% ammonium sulfate recovery) of homogeneous purified group A streptococcal M-protein is described. M-proteins extracted from whole cells of group A streptococci by treatment with hot HCl were neutralized, fractionated with ammonium sulfate, dialyzed, lyophilized, and then subjected to treatment with hot 60% trichloroacetic acid. This was shown to produce an M-protein preparation, free of group A carbohydrate activity and extraneous antigens, in yields up to 10-fold higher than previous methods in about one-fifth the time. These M-protein preparations were shown to: (i) have similar amino acid compositions to their respective type-specific proteins purified by diethylaminoethyl and O-(carboxymethyl) cellulose chromatography, (ii) react with their respective type-specific antisera in Ouchterlony diffusion, (iii) produce antisera in rabbits capable of promoting streptococcal long-chain formation in vitro, and (iv) give only one major band on polyacrylamide gel disk electrophoresis. The data allow for an explanation of the hitherto described multiple banding M-proteins seen on acrylamide electrophoresis.

Amino Acids↗

PubMed1972

Immunochemistry and end-group analyses of group A streptococcal M proteins.

Type-specific M proteins were examined to determine whether their immunological specificities were also reflected by major chemical differences. Sixteen different type-specific protein preparations were employed, including two from non-M-typable strains. These M proteins, acid-extracted from whole cells, were purified by ammonium sulfate fractionation and column chromatography and were compared by immunodiffusion, electrophoretic, amino acid, and N-terminal amino acid analyses. Although the data did not reflect major chemical distinctiveness in the types examined, some interesting results evolved. Four important factors were observed to be shared by all M protein types examined: (i) glutamic acid was the most prevalent amino acid, (ii) amino acid molar ratios were similar, (iii) each had l-alanine as a single N-terminus, and (iv) purified peaks from the column chromatograms still showed heterogeneity while giving type-specific reactivity for multiple bands. Thus, whereas chemical typing is apparently unfeasible, the data indicate that these may be unique proteins, reflected especially in the finding of the same N-terminus amino acid in all strains investigated.

Amino Acids↗

PubMedDate not supplied

Salicylate or bismuth salts enhance opsonophagocytosis of Klebsiella pneumoniae.

After treatment of encapsulated Klebsiella pneumoniae with salicylate or bismuth compounds, phagocytic uptake by human peripheral white blood cells or rat alveolar macrophages was assessed. Without salicylate pretreatment of bacteria, a 30-60% net increase in viable bacteria resulted in phagocytic assays after a 1 hour incubation. With salicylate pretreatment, dose-related decreases in bacterial counts were seen, achieving a maximal reduction of 60% with 240 microM salicylate pretreatment. Bacterial variants producing less capsule were more serum sensitive and more readily phagocytosed. Micrographs of Giemsa-stained cells revealed phagocytic uptake of multiple bacteria after salicylate pretreatment, but virtually no uptake of untreated bacteria. Opsonization with polyclonal antiserum decreased bacterial cell counts by 20% without and by 90% with salicylate pretreatment of bacteria. Pretreatment of bacteria with bismuth salts also enhanced opsonophagocytosis of encapsulated bacteria. Thus, agents known to reduce capsule expression in K. pneumoniae also enhance phagocytic uptake of bacteria.

Adult↗

PubMedDate not supplied

Salicylate-enhanced exposure of Klebsiella pneumoniae subcapsular components.

The capsular polysaccharide (CPS) of Klebsiella pneumoniae is an important virulence factor. Salicylate, which inhibits CPS production, was used to expose subcapsular antigens and components that may play an important role in host defense. Salicylate treatment greatly increased phagocytosis of five O1 serotypes by human polymorphonuclear leukocytes with normal rabbit serum and rabbit antisera against purified O1 lipopolysaccharide (O1LPS) as opsonins (p < 0.01 or < 0.05). Similar results were obtained with rabbit antiserum against a non-encapsulated isogenic strain. To further determine how salicylate increases susceptibility to phagocytosis, the binding of monoclonal antibodies against O1LPS or the LPS core and the binding of complement component C3b were measured by ELISA. The data indicate that salicylate reduced the barrier of CPS in serotypes O1:K1, O1:K10, and O1:K16 and unmasked subcapsular antigenic components in serotypes O1:K2 and O1:K66 so that bound opsonins could react with receptors on phagocytes. Serum bactericidal assays supported this conclusion. Therefore, decapsulating agents such as salicylate accentuate phagocytosis of K. pneumoniae by making subcapsular antigens and components accessible to immune and nonimmune host defences and vaccination with subcapsular antigens may exhibit optimal protection against lethal infection when combined with salicylate therapy.

Animals↗

PubMedDate not supplied

Efficacy of chlorine dioxide as a gas and in solution in the inactivation of two trichothecene mycotoxins.

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated. In the first experiment, verrucarin A (1, 5, or 10 microg) and roridin A (5 or 10 microg) were each inoculated onto square-inch sections of glass, paper, and cloth and exposed to 1000 ppm of ClO2 for either 24 or 72 h at room temperature. In the second experiment, verrucarin A and roridin A (1 or 2 ppm in water) were treated with 200, 500, or 1000 ppm ClO2 for up to 116 h at room temperature in light and dark conditions (N = 9 per treatment for test and control). A yeast assay using Kluyveromyces marxianuswas used to quantify the toxicity of verrucarin A and roridin A. Additionally, high-performance liquid chromatography was performed on selected samples. Results for the first experiment showed that ClO2 treatment had no detectable effect on either toxin. For the second experiment, both toxins were completely inactivated at all tested concentrations in as little as 2 h after treatment with 1000 ppm ClO2. For verrucarin A, an effect was seen at the 500 ppm level, but this effect was not as strong as that observed at the 1000 ppm level. Roridin A toxicity was decreased after treatment with 200 and 500 ppm ClO2, but this was not significant until the 24-h exposure time was reached. These data show that ClO2 (in solution) can be effective for detoxification of roridin A or verrucarin A at selected concentrations and exposure times.

Bioterrorism↗

PubMedDate not supplied

Factors influencing the adherence of Pseudomonas aeruginosa to mammalian buccal epithelial cells.

A correlation has previously been demonstrated between the in vitro adherence of Pseudomonas aeruginosa to upper respiratory tract epithelium of seriously ill patients and subsequent colonization of the respiratory tract by this opportunistic pathogen. Although the specific in vivo alterations in the cell surface that permit the adherence of P. aeruginosa have not been defined, we have demonstrated that P. aeruginosa adherence in vitro can be correlated with the loss of a protease-sensitive glycoprotein, fibronectin, from cell surface. The object of these studies was to correlate in vitro adherence of P. aeruginosa to buccal epithelial cells from patients with the levels of cell-surface fibronectin and of salivary proteases from the same patients, as well as to define the structure(s) on the bacterial surface important in the adherence process. A direct radioimmuno-binding assay was developed to measure cell-surface fibronectin, while protease activity in secretions was measured by 125I release from 125I-labelled insoluble fibrin matrices. Adherence of radiolabeled P. aeruginosa was directly related to decreased amounts of cell-surface fibronectin (P less than .001) and increased levels of salivary protease (P less than .001). Additionally, we demonstrated that pili may mediate the adherence of P. aeruginosa to buccal cells. This was shown by the ability of purified pili, when preincubated with buccal cells, to decrease the adherence of intact organisms from a mean of 30.6 organisms/cell to 5.7 organisms/cell (P less than .01).

Adhesiveness↗