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S Bergner-Rabinowitz

Publications and source records attributed to S Bergner-Rabinowitz.

At least 37 records · Page 2Linked to original sources
PubMed1972

Oxygen-stable hemolysins of group A streptococci. 8. Leukotoxic and antiphagocytic effects of streptolysins S and O.

Streptolysin S exists in a cell-bound form and as an extracellular complex between a nonspecific carrier (serum, serum albumin, ribonucleic acid [RNA], Triton, Tween) and a hemolytic moiety (probably a peptide) synthesized by streptococci. Although all the forms of streptolysin S, at 100 hemolytic units, killed mouse leukocyte monolayers, the time needed to kill 100% of the cells varied with the different streptolysin S preparations. Whereas 30 min was sufficient for the cell-bound hemolysin to kill all of the cells, 60 and 180 min were required when RNA streptolysin S and serum streptolysin S, respectively, were employed. Addition of 10% mouse serum to RNA streptolysin S or to cell-bound hemolysin delayed the killing of the leukocytes. The delayed killing observed with serum and albumin hemolysins is probably due to competition for the hemolytic moiety between the carrier molecules and target sites (phospholipids) upon the leukocyte membrane. Serum streptolysin S must be constantly incubated with the cells for 90 min for 100% of the cells to undergo cytopathic changes upon subsequent incubation for an additional 90 min. Streptolysin S inhibitor (trypan blue) added to the system after 30 or 60 min of incubation resulted in the killing of 50 and 100% of the leukocytes, respectively, when the cells were further incubated for 120 min. It is suggested that 30 min of incubation was not sufficient for the transfer of enough streptolysin S molecules upon the cell surface to allow killing of all of the cells. Sublethal amounts of streptolysin S, streptolysin O, and saponin suppressed phagocytosis of streptococci by mouse peritoneal macrophages. This effect was abolished by inhibitors of streptolysin S (trypan blue) and of streptolysin O and saponin (cholesterol). With sublethal amounts of streptolysin S, no inhibition of the reduction of nitro blue tetrazolium by nonphagocytosing cells was observed, but these amounts of streptolysin S caused a 50% inhibition of the reduction of nitro blue tetrazolium by phagocytosing leukocytes. It is suggested that some metabolic systems, which are normally enhanced during phagocytosis, have been affected by sublethal doses of streptolysin S. The results indicate that the in vivo production of small amounts of streptolysins S and O by group A streptococci may inhibit phagocytosis and may thus contribute to the invasiveness and pathogenicity of this microorganism.

Animals↗
PubMed1971

Application of enzyme production properties in subtyping of group A streptococci according to T type.

The production of extracellular nicotinamide adenine dinucleotide glycohydrolase (NADG) and the cell-bound lipoproteinase (serum opacity reaction, SOR) by strains of different serological types of group A streptococci, in relation to the T typing, was studied. The production of both NADG and SOR, or only one of them, was found to be characteristic of serotypes, as determined by M and T antigen. No difference in the production of these enzymes was found in relation to M-positive and M-negative variants. Investigation into NADG and SOR production as related to the T type enabled the division of a single agglutination pattern into four main groups, each of which corresponds to one specific M type or more. Of the 370 strains belonging to 12 different T-agglutination patterns, 21% produced both enzymes and 42.5% failed to produce any of them, whereas the remaining 36.5% produced only one out of the two enzymes. Five streptococcal types which did not produce NADG and SOR also failed to synthesize streptolysin S at the early logarithmic phase of growth, indicating that streptolysin S production by young cultures may be also related to serotype. No correlation was found between the production of NADG-SOR as related to serotype and the production of streptolysin O, acid phosphotase, esterase, N-acetylglucosaminidase, hyaluronidase, streptokinase, and the cell-sensitizing factor. The practical and potential usefulness of NADG and SOR production in epidemiological studies is discussed.

Agglutination Tests↗
PubMed1969

Effect of pH on in vitro phagocytosis of Streptococcus pyogenes.

Phagocytosis experiments were performed with mouse peritoneal leucocytes (MPL). The natural pH of the mouse peritoneal cavity was found to be between 6.1 and 6.3. The phagocytic and intracellular killing activities of MPL by pH variations was studied. It was observed that the optimal ingestion and intracellular killing of bacteria is at the natural pH of the peritoneal cavity.

Animals↗