It is postulated that lysosomal enzymes of leukocytes are capable of breaking down bacterial constituents and to cause bacteriolyasis. Studies from our laboratory have shown that radiolabled staphylococci (log-phase) arm readily lysed by leukocyte extracts at pH 5.0. On the other hand, old cells or heat-killed young cells are resistant degradation. The leukocytes extracts can be affectively replaced by cationic proteins as well as by membrane-damaging agents (phospholipase A2, polymaxins). Studies on the mechanisms of bacteriolysis have suggested that the cationic proteins act by activating the bacterial autolytic enzymes leading to bacteriolysis. This proces can be inhibited by a series of anionic polalalectrolytes likely to preent in inflammation, presumably by inactivating autolytic enzymes. The cooperation between PHNs and macrophages in bacteriolysis and control of bacterial growth by polalalectrolytes will be discussed in relation to the phatogenesis of the infection and inflammation.
Yosef Kaplan was one of the leaders of the Jewish underground in the Warsaw ghetto, and an important member of Hechalutz and Hashomer Hatzair. Eyewitness accounts, articles, and documents describe his home and childhood, his involvement in the youth movement of Hashomer Hatzair in Kalisz, Poland, and his work as a member of the executive committee in Warsaw.
The distribution of the methylatable sites GATC and CCATGG was studied by analyzing the molecular average size of restriction fragments of E. coli DNA. Both sites were found to be randomly distributed, reflecting a random pattern of methylation. The methylation pattern of specific sequences such as the origin of replication and rRNA genes has been studied in wild type E. coli and a methylation deficient (dam- dcm-) mutant. These sequences were found to be methylated in wild type cells and unmethylated in the mutant indicating that there is no effect of the state of methylation of these sequences on their expression. Analysis of the state of methylation of GATC sites in newly replicating DNA using the restriction enzyme Dpn I (cleaves only when both strands are methylated) revealed no detectable hemimethylated DNA suggesting that methylation occurs at the replication fork. Taking together the results presented here and previously published data (5), we arrive at the conclusion that the most likely function of E. coli DNA methylations is probably in preventing nuclease activity.
