Mucopolysaccharidase-producing oral bacteria may contribute to the pathogenesis of inflammatory periodontal disease in several ways. Bacterial mucopolysaccharidases, in the area of the gingival crevice, can destroy important components of the ground substance of connective tissue leading to periodontal destruction on the one hand and enhancing the spread of bacterial toxins on the other. Partial breakdown of proteoglycan due to penetration of small amounts of these enzymes may also expose cryptic antigenic determinants, resulting in destructive autoimmune reactions. Finally, mucopolysaccharidase-producing oral bacteria may interact symbiotically with other pathogens of the gingival sulcus by enzymatic breakdown of tissue to release fermentable substrates for these pathogens. / In the present investigation, it has been shown that anaerobic mucopolycaccharidase-producing bacteria are common inhabitants of gingival sulci of humans and that these microorganisms significantly increase in number in periodontal pockets of patients with inflammatory periodontal disease. Peptostreptococci probably are the most predominant producers of mucopolysaccharidases by virtue of their occurrence in subgingival plaque as well as the abundance of enzyme they produce. Peptostreptococci strains isolated from diseased periodontal pockets have been observed to convert from rough-colony-forming cells to smooth-colony-forming variants upon culturing in vitro. In dental plaque, hyaluronidase-producing peptostreptococci exist predominantly as the rough-colony-forming variants which produce higher amounts of hyaluronidase. Purified extracellular hyaluronidase from Peptostreptococcus strain 84H14S is different from previously reported bacterial hyaluronidases in several respects. It has different substrate specificity and optimum pH for activity. Also, the specific activity of this enzyme is much higher than any previously purified mucopolysaccharidases. Peptostreptococcus strain 84H14S is further shown to release potent cytotoxic factors into the culture medium, in addition to hyaluronidase, during its growth cycle. This may confer additional virulence to this bacterial genus in periodontal disease.

Neisseria meningitidis SD1C exhibited a low tolerance to penicillin G (0.03 (mu)g/ml). Loss of viability was independent of the concentration of antibiotic above the minimum inhibitory concentration, whereas the rate of bacteriolysis was concentration dependent. Penicillin-induced lysis was secondary to cell death. At low but lethal levels of this antibiotic, rapid loss of viability was accompanied by specific ultrastructural changes, yet growth characteristics appeared normal. Subminimal inhibitory concentrations of penicillin G decreased cell numbers and altered the colonial morphology, cellular ultrastructure, as well as the division rate. N. meningitidis SD1C was shown to have six penicillin binding proteins. The binding of penicillin was rapid and for certain proteins was dependent upon concentration and active cell growth. No single penicillin binding protein could be correlated with cell death. Penicillin treatment of cells in the presence of polyvinylpyrrolidone-40 and horse serum resulted in an inhibition of cell division, yet no loss in viability, no ultrastructural changes nor reduction of penicillin binding to the cells occurred. Protection from the antibiotic was shown to be related at least in part to the ability of such collids to eliminate a penicillin G induced increase in intracellular H(,2)O volume. This antibiotic was also shown to cause a concurrent increase in transmembrane potential and intracellular potassium ion level. The relationship of these findings to the lethal events in N. meningitidis is discussed and a model is proposed for the mode of action of penicillin G.

In Salmonella typhimurium, PhoP is the response regulator of the PhoP/PhoQ two-component regulatory system. Gel filtration chromatography showed that PhoP exists as a mixture of monomer and dimer regardless of its phosphorylation state. Unphosphorylated PhOPHis (a mutant harboring a histidine tag at the C-terminus) was mostly monomeric, whereas PhoP His~P existed as a mixture of monomer and dimer. Binding of PhoP to the PhoP box was barely influenced by phosphorylation as determined by surface plasmon resonance. In contrast, phosphorylation of PhoPHis induced a 200% increase in PhoPHis binding to target DNA. Fluorescence analysis revealed that the conformation of PhOPHis is greatly altered compared to that of wild-type PhoP. Altogether, these data show that a His tag at the C-terminus of PhoP affects its biochemical properties, most likely by affecting its conformation. More importantly, these results show that wild-type PhoP dimerization and interaction with target DNA are independent of phosphorylation.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5720. Adviser: Clay Fuqua. Title from dissertation home page (viewed May 9, 2008).

Thesis (Ph.D.)--Yeshiva University, 2006. / (UnM)AAI3205973. Adviser: Marshall S. Horwitz. Source: Dissertation Abstracts International, Volume: 67-02, Section: B, page: 0681.

Thesis (Ph.D.)--University of California, San Francisco, 2006. / Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0074. Adviser: Jeffery S. Cox.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006. / Title from PDF t.p. (viewed Nov. 14, 2008). Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0079. Adviser: Clay Fuqua.

Thesis (Ph.D.)--University of California, San Francisco, 2007. / Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7102. Adviser: Eric J. Brown.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007. / Title from dissertation home page (viewed May 28, 2008). Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7101. Adviser: Yves Brun.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4258. Adviser: John E. Cronan, Jr. Includes bibliographical references (leaves 123-133) Available on microfilm from Pro Quest Information and Learning.