by Carrie Au-Yeang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 45-54). / Abstract also in Chinese. / Chapter I. --- Abstract --- p.iii / Chapter II. --- Acknowledgements --- p.iv / Chapter III. --- Table of Contents --- p.v / Chapter IV. --- List of Abbreviations --- p.vii / Chapter V. --- List of Figures --- p.viii / Chapter VI. --- List of Tables --- p.ix / Chapter VII. --- Introduction --- p.1 / Chapter VIII. --- Literature Review --- p.3 / Chapter A. --- Mycobacterium tuberculosis Infections - clinical importance --- p.3 / Chapter B. --- Treatment of M. tuberculosis Infections - the past & present --- p.3 / Chapter C. --- Laboratory Supports for Treatment of Tuberculosis --- p.5 / Chapter D. --- The Postantibiotic Effects (PAE) --- p.6 / Chapter E. --- PAE of Antituberculosis Drugs Against Mycobacteria --- p.15 / Chapter F. --- Radiometric Measurement of growth --- p.16 / Chapter IX. --- Materials and Methods --- p.17 / Chapter A. --- Bacterial Strains and Their Maintenance --- p.17 / Chapter B. --- Antimicrobial Agents --- p.17 / Chapter C. --- Antimicrobial Susceptibility Testing --- p.18 / Chapter D. --- Assessment of PAE and KI In Vitro --- p.20 / Chapter E. --- Assessment of PAE and KI Ex Vivo --- p.22 / Chapter F. --- Determination of Drug Uptake --- p.25 / Chapter X. --- Results --- p.29 / Chapter A. --- In Vitro Susceptibility Testing of the M. tuberculosis Strains --- p.29 / Chapter B. --- PAE In Vitro - the Classical Viable Count Method --- p.29 / Chapter C. --- PAE Measured by the Bactec Method --- p.30 / Chapter D. --- PAE In Vitro - the Bactec Method --- p.30 / Chapter E. --- Postantibiotic Effects Ex Vivo by the Bactec Method --- p.31 / Chapter F. --- Bactericidal Activities In Vitro and Ex Vivo --- p.32 / Chapter XI. --- Discussion --- p.34 / Chapter A. --- Selection of M. tuberculosis isolates and Drug Susceptibility --- p.34 / Chapter B. --- PAE and KI In Vitro & Ex Vivo - the study methods --- p.34 / Chapter C. --- PAE In Vitro & Ex Vivo - single drug --- p.36 / Chapter D. --- PAE Ex Vivo - drug combinations --- p.38 / Chapter E. --- KI In vitro & Ex vivo --- p.39 / Chapter F. --- PAE and Clinical Therapeutic Regimens --- p.41 / Chapter G. --- Conclusion & Future Studies --- p.44 / Chapter XII. --- Literature Cited --- p.45 / Chapter XIII. --- Figures --- p.55 / Chapter IVX --- Tables --- p.68

Indiana University-Purdue University Indianapolis (IUPUI) / The primary goal of root canal treatment is to eliminate microbes from the root canal system, which is the cause of pulpal and periapical infections. Research shows that after a single visit of chemomechanical debridement microbes continue to remain within the canal system. An interappointment medication step has been advocated to maximize potential elimination of microbes within the root canal system. Previous studies have shown propolis to be antibacterial against common endodontic microbes. Studies have shown trends in different microbes being present in primary verus secondary endodontic infections. The majority of literature has focused on the efficacy of propolis against Enterococcus faecalis, a microbe commonly implicated in secondary endodontic 95 infections. The aim of this study was to demonstrate the efficacy of propolis against Fusobacterium nucleatum, a microbe commonly found in primary endodontic infections. This study aims to demonstrate the efficacy of propolis against a bacterium of primary endodontic infections (F. nucleatum) as well as against microbial biofilm to further support its potential use as a novel intracanal medicament. Dilutions of propolis were added to cultures of F. nucleatum in microtiter plates in a range from 390 μg/ml to 50,000 μg/ml. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the minimum biofilm inhibitory concentration (MBIC) were determined. The MIC was determined of the total solution (biofilm+planktonic), planktonic, and biofilm (MBIC) after a 48-hour incubation period. The MBIC was determined by fixing biofilm to the wells and using crystal violet staining with spectrophotometry. The MBC was examined by plating solution from each concentration test well and reading the plates after 48 hours of incubation. The results show that the MIC of the total (biofilm+planktonic) appears to occur at a concentration of 6250 μg/ml. The MBIC appears to occur at the concentration of 1562.5 μg/ml. The planktonic results exhibit no significant difference in test and control wells. There was no MBC at any of the test concentrations. The propolis appears to inhibit bacterial growth and biofilm formation but does not appear to be bactericidal at any of the tested concentrations. The results of this study indicate that propolis has an MIC and MBIC when tested in vitro against F. nucleatum, although it does not show an MBC. There appears to be potentially significant interaction of propolis with biofilm as displayed by the lower concentration needed to exibit inhibitory effects on biofilm formation. This information 96 may contribute to the ability to develop a proper concentration of propolis to use in vivo when treating endodontic infections.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Regenerative endodontic therapy in immature teeth with necrotic pulps triggers continued root development, thereby improving the prognosis of these teeth. Disinfection of the canal is accomplished with an intracanal medicament, such as triple antibiotic paste (TAP) composed of metronidazole, ciprofloxacin, and minocycline. A modified triple antibiotic paste (MTAP) that replaces minocycline with clindamycin has recently been suggested to avoid the tooth discoloration and potential demineralization from minocycline. The effect these pastes have on radicular dentin is unknown. Objectives: The aim of this study was to investigate the effects of two intracanal medicaments used during endodontic regeneration, TAP and MTAP, at concentrations of 1 g/mL and 1 mg/mL, on the microhardness and chemical structure of radicular dentin. Materials and Methods: Roots from extracted, unrestored, non-carious human premolar teeth were sectioned. An antibiotic paste (MTAP or TAP) or sterile water (control) was applied to treatment groups and stored for four weeks in 80-percent humidity at 37 °C. The effect of each paste on the microhardness of radicular dentin was measured using a Vickers Microhardness Tester (n = 17) to take three pretreatment and post-treatment measurements at both 500 µm and 1000 µm from the pulp-dentin interface. The chemical structure was assessed from dentin specimens treated with the same medicaments or sterile water for four weeks. After treatment, three measurements were taken on each specimen using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy to measure the phosphate/amide I ratios of dentin (n = 7). Results: The 1 g/mL of TAP or MTAP and the 1 mg/mL methylcellulose-based TAP caused significant reduction in microhardness of roots compared with untreated control roots at 500 µm and 1000 µm from the pulp-dentin interface. Furthermore, the methylcellulose-based 1 mg/mL TAP and MTAP caused significantly less reduction in microhardness compared with 1 g/mL TAP and MTAP. The 1 g/mL of TAP and DAP caused significantly lower phosphate/amide I ratios compared with other groups. Conclusion: The use of methylcellulose based 1 mg/mL of TAP and MTAP may minimize the reduction in microhardness of roots compared with the currently used 1 g/mL concentration of these antibiotics.

Chlamydiae growing in target mucosal human epithelial cells in vitro can transition from their normal developmental cycle progression, alternating between infectious but metabolically inactive elementary bodies to metabolically active but noninfectious reticulate bodies (RBs) and back to elementary bodies, into a state of persistence. Persistence in vitro is defined as viable but noncultivable chlamydiae involving morphologically enlarged, aberrant, and nondividing RBs. The condition is reversible, yielding infectious elementary bodies after removal of the inducers, including penicillin, interferon-gamma, iron or nutrient starvation, concomitant herpes infection, or maturation of the host cell into its physiologically differentiated state. All aberrant RB phenotypes are not the same, owing to differing up- or down-regulated chlamydial gene sets and subsequent host responses. Although all persistence-inducing conditions exist in vivo, key questions include (1) whether or not aberrant chlamydial RBs occur in vivo during the alternating acute-silent chronic-acute chlamydial infection scenario that exists in infected patients and animals and (2) whether such aberrant RBs can contribute to prolonged, chronic inflammation, fibrosis, and scarring.