Oral antibacterial effect of chlorhexidine treatments and professional prophylaxis in children

Aim: The primary aim of this longitudinal study was to evaluate additional effects of 4-week chlorhexidine digluconate (CHX) gel treatments to control Aggregatibacter actinomycetemcomitans counts in children after professional dental prophylaxis. Porphyromonas gingivalis and Streptococcus mutans counts were also determined to evaluate the secondary effects of anti-plaque treatments on microbial shifts. Methods: Twenty-six children with A. actinomycetemcomitans counts >4 log10/ mL of saliva and/or Quigley-Hein plaque index >3.0 were enrolled in this study. Patients were randomly assigned to groups GI (placebo gel), GII (0.5% CHX gel), GIII (1% CHX gel), and GIV (2% CHX gel). Four sessions of treatment were performed during 4 weeks after a session of professional dental prophylaxis. Real-Time polymerase chain reaction (PCR) was used to determine viable microorganism counts in non-stimulated whole saliva samples collected at baseline, one week, one month and three months after interruption of treatments. Results: A reduction of all bacterial counts was detected after the 3-month follow-up in all groups. Lower counts of P. gingivalis were achieved from 1 week on after treatments. The 2% CHX concentration seemed to contribute to lower A. actinomycetemcomitans levels and increase S. mutans levels. Conclusions: Professional dental prophylaxis was effective to control salivary levels of A. actinomycetemcomitans, P. gingivalis and S. mutans. Additional antimicrobial effects, however, were not observed by the combination of professional dental prophylaxis and 4-week chlorhexidine gel treatments.

A preliminary study of the antibacterial potential of cetylpyridinium chloride in root canals infected by E. faecalis

The aim of this preliminary study was to verify the antibacterial potential of cetylpyridinium chloride (CPC) in root canals infected by Enterococcus faecalis. Forty human maxillary anterior teeth were prepared and inoculated with E. faecalis for 60 days. The teeth were randomly assigned to the following groups: 1: Root canal preparation (RCP) + 0.1% CPC with positive-pressure irrigation (PPI, Conventional, NaviTip®); 2: RCP + 0.2% CPC PPI; 3: RCP + 2.5% NaOCl PPI; 4: RCP + 2.5% NaOCl with negative-pressure irrigation system (NPI, EndoVac®); 5: Positive control; and 6: Negative control. Four teeth of each experimental group were evaluated by culture and 4 by scanning electron microscopy (SEM). In all teeth, the root canals were dried and filled with 17% EDTA (pH 7.2) for 3 min for smear layer removal. Samples from the infected root canals were collected and immersed in 7 mL of Letheen Broth (LB), followed by incubation at 37°C for 48 h. Bacterial growth was analyzed by turbidity of culture medium and then observed with a UV spectrophotometer. The irrigating solutions were further evaluated for antimicrobial effect by an agar diffusion test.The statistical data were treated by means, standard deviation, Kruskal-Wallis test and analysis of variance. Significance level was set at 5%. The results showed the presence of E. faecalis after root canal sanitization. The number of bacteria decreased after the use of CPC. In the agar diffusion test, CPC induced large microbial inhibition zones, similar to 2% chlorhexidine and large than 2.5% NaOCl. In conclusion, cetylpyridinium chloride showed antibacterial potential in endodontic infection with E. faecalis.

Bedeutung N- und C-terminaler Aminosäuren für die Monomer- und Dimerbildung von Lichtsammelproteinen des Photosystems I

Der LHCI-730 ist ein heterodimerer, Chlorophyll a/b-bindender Lichtsammelkomplex (LHC) des Photosystem I in höheren Pflanzen. Mit Hilfe rekombinanter, modifizierter Proteine wurde untersucht, welche terminalen Bereiche der Untereinheiten Lhca1 und Lhca4 für die Bildung von monomeren und dimeren Lichtsammelproteinen relevant sind. Durch PCR-Mutagenese modifizierte Apoproteine wurden in vitro mit Gesamtpigmentextrakt rekonstituiert und auf ihre Fähigkeit mono- bzw. dimere LHCs zu bilden untersucht.Für die Monomerbildung sind der extrinsische N-Terminus und die der amphipathischen vierten Helix folgenden Aminosäuren beider Proteine für die Faltung stabiler monomerer Pigmentproteinkomplexe nicht notwendig. Die Aminosäuren, mit deren Deletion die Monomerbildung an N- und C-Terminus verhindert wurde, verfügten über geladene (Glu, Asp), aromatische (Trp) oder neutrale Seitenketten (Leu).Die Untersuchungen zur Dimerbildung des LHCI-730 zeigten, daß am N-Terminus des Lhca1 nur bis zu einer Entfernung von drei Aminosäuren (Trp) eine Assemblierung der Untereinheiten möglich ist. Nur Phe (anstatt Trp) war in Substitutionsexperimenten im Vollängenprotein in der Lage, Dimere zu bilden. Das Ausbleiben der Dimerbildung der bis einschließlich zum Trp-39 und Ile-168 verkürzten Deletionsmutanten des Lhca4 ist vermutlich auf die Instabilität dieser Lhca4-Mutanten zurückzuführen. Die Deletion von Trp-185 am C-Terminus des Lhca1 führt zu einem Ausbleiben der Dimerbildung, die aber offensichtlich durch weitere, zuvor schon deletierte Aminosäuren beeinträchtigt wurde.

Statistical Mechanics of Monomer-Dimer Models on Complete and Erdös-Rényi Graphs

Nella tesi sono trattate due famiglie di modelli meccanico statistici su vari grafi: i modelli di spin ferromagnetici (o di Ising) e i modelli di monomero-dimero. Il primo capitolo è dedicato principalmente allo studio del lavoro di Dembo e Montanari, in cui viene risolto il modello di Ising su grafi aleatori. Nel secondo capitolo vengono studiati i modelli di monomero-dimero, a partire dal lavoro di Heilemann e Lieb,con l'intento di dare contributi nuovi alla teoria. I principali temi trattati sono disuguaglianze di correlazione, soluzioni esatte su alcuni grafi ad albero e sul grafo completo, la concentrazione dell'energia libera intorno al proprio valor medio sul grafo aleatorio diluito di Erdös-Rényi.

Polymerisation in perfluorierter Emulsion

Die vorliegende Arbeit behandelt die Polymerisation in nicht-wässrigen Emulsionen – bestehend aus einem perfluorierten Solvens und einem Kohlenwasserstoff - unter Einsatz verschiedener Monomere, Katalysatoren und Polymeristionsmethoden zur Generierung von Polymerpartikeln verschiedenster Art. Es wurde gezeigt, dass in diesen inerten Medien zahlreiche Methoden zur Polymererzeugung unter gleichzeitiger Morphologiekontrolle eingesetzt werden können, die in konventionellen wässrigen, heterophasischen Systemen versagen.rnrnAusgangspunkt war die literaturbekannte Metallocen-katalysierte Synthese von Polyethylen (PE)- und Polypropylen (PP)-Nanopartikeln in perfluorierter Emulsion in Gegenwart hochmolekularer Blockcopolymere als Stabilisierungsagens. Mithilfe kinetischer Untersuchungen hinsichtlich der PE-Synthese wurde im Rahmen dieser Arbeit ein Modell entwickelt, welches den Diffusionsweg eines gasförmigen Monomers über die verschiedenen Phasengrenzen hinweg zum aktiven katalytischen Zentrum in der dispergierten Phase beschreibt. Ferner konnte die Diffusions- und Reaktionsbestimmtheit der Reaktion in Abhängigkeit verschiedener Reaktionsparameter nachgewiesen sowie ein tieferer Einblick über den Ort der Polymerisation in den heterophasischen Systemen erhalten werden.rnrnDie so gewonnenen Erkenntnisse wurden für die erfolgreiche Synthese von Poly(ethylen-1-hexen)-Copolymeren in perfluorierter Emulsion genutzt, wobei der Comonomergehalt im resultierenden Polymer über einen breiten Bereich variiert werden konnte. Neben der Homo- und Copolymerisation von Polyolefinen wurde in der vorliegenden Arbeit weiter gezeigt, dass die heterogenen Fluide zum Aufbau komplexerer Morphologien wie Kern-Schale-Nanopartikeln genutzt werden können; so gelangte man zu Partikeln mit Kernen aus isotaktischem PP, ummantelt von „weichem“ Poly(n-butylacrylat).rnrnEin weiterer Fokus dieser Arbeit lag auf der Erweiterung der Anwendungsmöglichkeiten der perfluorierten Emulsionen, und so wurde bspw. der Zugang zu Polymerdispersionen aus konjugierten Materialien mit Partikeldurchmessern von 70-100 nm mittels Cyclopolymerisation eröffnet. Ferner konnten als bioverträgliche und biologisch abbaubare Materialien Partikel aus epsilon-Caprolacton in koordinativ-anionischer Polymerisation gewonnen werden. Im Zuge dessen wurden Emulgatoren entwickelt, die den Einsatz polarer Monomere in perfluorierter Emulsion erlauben.rnrnSchlussendlich konnten mittels trifunktioneller Polymere mit lipophilen und fluorophilen Gruppen sowie Lewis-basischen Ankergruppen Ag- und Cu-Partikel dergestalt oberflächenmodifiziert werden, dass ein homogenes Einbetten in eine perfluorierte Matrix möglich war, was antibakterielle perfluorierte Werkstoffe - erwiesen an E. coli - lieferte.

Dielectrophoresis (dep) and electrowetting (ewod) as an anti-fouling process for antibacterial surfaces

Nowadays the medical field is struggling to decrease bacteria biofilm formation which leads to infection. Biomedical devices sterilization has not changed over a long period of time. This results in high costs for hospitals healthcare managements. The objective of this project is to investigate electric field effects and surface energy manipulation as solutions for preventing bacteria biofilm for future devices. Based on electrokinectic environments 2 different methods were tested: feasibility of electric gradient through mediums (DEP) reinforced by numerical simulations; and EWOD by the fabrication of golden interdigitated electrodes on silicon glass substrates, standard ~480 nm Teflon (PTFE) layer and polymeric gasket to contain the bacteria medium. In the first experiment quantitative analysis was carried out to achieve forces required to reject bacteria without considering dielectric environment limitations as bacteria and medium frequency dependence. In the second experiment applied voltages was characterized by droplets contact angle measurements and put to the live bacteria tests. The project resulted on promising results for DEP application due to its wide range of frequency that can be used to make a “general” bacteria rejecting; but in terms of practicality, EWOD probably have higher potential for success but more experiments are needed to verify if can prevent biofilm adhesion besides the Teflon non-adhesive properties (including limitations as Teflon breakthrough, layer sensitivity) at incubation times larger than 24 hours.

Design of nanoparticle systems with antimicrobial properties

Infektiöse Komplikationen im Zusammenhang mit Implantaten stellen einen Großteil aller Krankenhausinfektionen dar und treiben die Gesundheitskosten signifikant in die Höhe. Die bakterielle Kolonisation von Implantatoberflächen zieht schwerwiegende medizinische Konsequenzen nach sich, die unter Umständen tödlich verlaufen können. Trotz umfassender Forschungsaktivitäten auf dem Gebiet der antibakteriellen Oberflächenbeschichtungen ist das Spektrum an wirksamen Substanzen aufgrund der Anpassungsfähigkeit und Ausbildung von Resistenzen verschiedener Mikroorganismen eingeschränkt. Die Erforschung und Entwicklung neuer antibakterieller Materialien ist daher von fundamentaler Bedeutung.rnIn der vorliegenden Arbeit wurden auf der Basis von Polymernanopartikeln und anorganischen/polymeren Verbundmaterialien verschiedene Systeme als Alternative zu bestehenden antibakteriellen Oberflächenbeschichtungen entwickelt. Polymerpartikel finden Anwendung in vielen verschiedenen Bereichen, da sowohl Größe als auch Zusammensetzung und Morphologie vielseitig gestaltet werden können. Mit Hilfe der Miniemulsionstechnik lassen sich u. A. funktionelle Polymernanopartikel im Größenbereich von 50-500 nm herstellen. Diese wurde im ersten System angewendet, um PEGylierte Poly(styrol)nanopartikel zu synthetisieren, deren anti-adhesives Potential in Bezug auf P. aeruginosa evaluiert wurde. Im zweiten System wurden sog. kontakt-aktive kolloide Dispersionen entwickelt, welche bakteriostatische Eigenschaften gegenüber S. aureus zeigten. In Analogie zum ersten System, wurden Poly(styrol)nanopartikel in Copolymerisation in Miniemulsion mit quaternären Ammoniumgruppen funktionalisiert. Als Costabilisator diente das zuvor quaternisierte, oberflächenaktive Monomer (2-Dimethylamino)ethylmethacrylat (qDMAEMA). Die Optimierung der antibakteriellen Eigenschaften wurde im nachfolgenden System realisiert. Hierbei wurde das oberflächenaktive Monomer qDMAEMA zu einem oberflächenaktiven Polyelektrolyt polymerisiert, welcher unter Anwendung von kombinierter Miniemulsions- und Lösemittelverdampfungstechnik, in entsprechende Polyelektrolytnanopartikel umgesetzt wurde. Infolge seiner oberflächenaktiven Eigenschaften, ließen sich aus dem Polyelektrolyt stabile Partikeldispersionen ohne Zusatz weiterer Tenside ausbilden. Die selektive Toxizität der Polyelektrolytnanopartikel gegenüber S. aureus im Unterschied zu Körperzellen, untermauert ihr vielversprechendes Potential als bakterizides, kontakt-aktives Reagenz. rnAufgrund ihrer antibakteriellen Eigenschaften wurden ZnO Nanopartikel ausgewählt und in verschiedene Freisetzungssysteme integriert. Hochdefinierte eckige ZnO Nanokristalle mit einem mittleren Durchmesser von 23 nm wurden durch thermische Zersetzung des Precursormaterials synthetisiert. Durch die nachfolgende Einkapselung in Poly(L-laktid) Latexpartikel wurden neue, antibakterielle und UV-responsive Hybridnanopartikel entwickelt. Durch die photokatalytische Aktivierung von ZnO mittels UV-Strahlung wurde der Abbau der ZnO/PLLA Hybridnanopartikel signifikant von mehreren Monaten auf mehrere Wochen verkürzt. Die Photoaktivierung von ZnO eröffnet somit die Möglichkeit einer gesteuerten Freisetzung von ZnO. Im nachfolgenden System wurden dünne Verbundfilme aus Poly(N-isopropylacrylamid)-Hydrogelschichten mit eingebetteten ZnO Nanopartikeln hergestellt, die als bakterizide Oberflächenbeschichtungen gegen E. coli zum Einsatz kamen. Mit minimalem Gehalt an ZnO zeigten die Filme eine vergleichbare antibakterielle Aktivität zu Silber-basierten Beschichtungen. Hierbei lässt sich der Gehalt an ZnO relativ einfach über die Filmdicke einstellen. Weiterhin erwiesen sich die Filme mit bakteriziden Konzentrationen an ZnO als nichtzytotoxisch gegenüber Körperzellen. Zusammenfassend wurden mehrere vielversprechende antibakterielle Prototypen entwickelt, die als potentielle Implantatbeschichtungen auf die jeweilige Anwendung weiterhin zugeschnitten und optimiert werden können.

Rigorous results in Spin Glasses and Monomer-Dimer systems

In this work I reported recent results in the field of Statistical Mechanics of Equilibrium, and in particular in Spin Glass models and Monomer Dimer models . We start giving the mathematical background and the general formalism for Spin (Disordered) Models with some of their applications to physical and mathematical problems. Next we move on general aspects of the theory of spin glasses, in particular to the Sherrington-Kirkpatrick model which is of fundamental interest for the work. In Chapter 3, we introduce the Multi-species Sherrington-Kirkpatrick model (MSK), we prove the existence of the thermodynamical limit and the Guerra's Bound for the quenched pressure together with a detailed analysis of the annealed and the replica symmetric regime. The result is a multidimensional generalization of the Parisi's theory. Finally we brie y illustrate the strategy of the Panchenko's proof of the lower bound. In Chapter 4 we discuss the Aizenmann-Contucci and the Ghirlanda-Guerra identities for a wide class of Spin Glass models. As an example of application, we discuss the role of these identities in the proof of the lower bound. In Chapter 5 we introduce the basic mathematical formalism of Monomer Dimer models. We introduce a Gaussian representation of the partition function that will be fundamental in the rest of the work. In Chapter 6, we introduce an interacting Monomer-Dimer model. Its exact solution is derived and a detailed study of its analytical properties and related physical quantities is performed. In Chapter 7, we introduce a quenched randomness in the Monomer Dimer model and show that, under suitable conditions the pressure is a self averaging quantity. The main result is that, if we consider randomness only in the monomer activity, the model is exactly solvable.

Synthesis and characterization of polymeric ionic liquid through free radical polymerization of acryloyl imidazolium-based ionic liquid monomer

This thesis investigates the synthesis of polymeric ionic liquid [(poly-acryloyloxy)6C6C1im][NTf2], by free radical polymerization of acryloyl imidazolium-base ionic liquid monomer [(acryloyloxy)6C6C1im][NTf2]. Moreover, the smartest synthetic route to obtain this monomer was investigated. Two different synthesis were compared. The first one started from the preparation of the monomer 6-chlorohexyl acrylate followed by substitution and metathesis to reach ionic liquid monomer. The second one started from synthesis of the ionic liquid [(HO)6C6C1im]Cl followed by metathesis and esterification in order to get ionic liquid monomer [(acryloyloxy)6C6C1im][NTf2].

Clinical and antibacterial effect of an anti-inflammatory toothpaste formulation with Scutellaria baicalensis extract on experimental gingivitis

It was the aim of the study to evaluate the clinical and antibacterial effect of a dentifrice containing an anti-inflammatory plant extract (SB) versus a placebo (PLA) using an experimental gingivitis model. Forty subjects (20 per group) discontinued all oral hygiene measures for four teeth for a period of 21 days using a shield (to generate a possible gingivitis) while they could brush the other teeth normally. After brushing, the shield was removed and teeth were treated with the randomly assigned toothpaste slurry for 1 min. Löe and Silness gingival index (GI), Silness and Löe plaque index (PI), and biofilm vitality (VF%) were assessed at days 0, 14, and 21, respectively. Subjects of the PLA group developed a GI of 0.82?±?0.342 (day 14) and 1.585?±?0.218 (day 21), while the data of the SB group were significantly reduced (0.355?±?0.243 and 0.934?±?0.342, p?

In vitro cytotoxicity of silver nanoparticles on osteoblasts and osteoclasts at antibacterial concentrations

Abstract Nanoparticulate silver coatings for orthopaedic implants promise to decrease postoperative infection rates. However, silver-induced cytotoxicity on bone cells has not been investigated in detail. This study investigated the cytotoxic effects of silver nano- and microparticles and Ag(+) on osteoblasts (OBs) and osteoclasts (OCs) and correlated their effects with the antibacterial efficacy on Staphylococcus epidermidis. Silver nanoparticles (50 nm) exhibited strong cytotoxic effects on OBs and OCs. Weak cytotoxic effects were observed for silver microparticles (3 μm). The cytotoxicity was primarily mediated by a size-dependent release of Ag(+). Antibacterial effects occurred at Ag(+) concentrations that were 2-4 times higher than those inducing cytotoxic effects. Such adverse effects on OB and OC survival may have deleterious effects on the biocompatibility of orthopaedic implants. Our study represents an important step toward the detailed investigation of orthopaedic implant with nanoparticulate silver coatings prior to their widespread clinical usage.

Antibacterial effect of taurolidine (2%) on established dental plaque biofilm

Preliminary data have suggested that taurolidine may bear promising disinfectant properties for the therapy of bacterial infections. However, at present, the potential antibacterial effect of taurolidine on the supragingival plaque biofilm is unknown. To evaluate the antibacterial effect of taurolidine on the supragingival plaque biofilm using the vital fluorescence technique and to compare it with the effect of NaCl and chlorhexidine (CHX), 18 subjects had to refrain from all mechanical and chemical hygiene measures for 24 h. A voluminous supragingival plaque sample was taken from the buccal surfaces of the lower molars and wiped on an objective slide. The sample was then divided into three equal parts and mounted with one of the three test or control preparations (a) NaCl, (b) taurolidine 2% and (c) CHX 0.2%. After a reaction time of 2 min, the test solutions were sucked of. Subsequently, the plaque biofilm was stained with fluorescence dye and vitality of the plaque flora was evaluated under the fluorescence microscope (VF%). Plaque samples treated with NaCl showed a mean VF of 82.42 ± 6.04%. Taurolidine affected mean VF with 47.57 ± 16.60% significantly (p < 0.001, paired t test). The positive control CHX showed the lowest mean VF values (34.41 ± 14.79%; p < 0.001 compared to NaCl, p = 0.017 compared to taurolidine). Taurolidine possesses a significant antibacterial effect on the supragingival plaque biofilm which was, however, not as pronounced as that of CHX.

Synthesis of 1,1'-(Hexane-1,6-Diyl)Bis(5-Oxopyrrolidine-3-Carboxylic Acid) as a Monomer for a Polyanhydride Drug Delivery System

Polyanhydrides have been given much attention in the literature recently because of their desirable properties as controlled drug delivery solutions. Drug therapies could be loaded into a polyanhydride matrix and protected from denaturation and removal from the body while being slowly eluted as the polyanhydride degraded yielding a tailorable concentration profile in the bloodstream at therapeutic levels. To that end, this report discusses the synthesis of a novel monomer for polyanhydride synthesis: 1,1'-(hexane-1,6-diyl)bis(5-oxopyrrolidine-3-carboxylic acid) henceforth known as CPyH monomer for (carboxypyrrolidone)hexane monomer.

Antibacterial and antiinflammatory kinetics of curcumin as a potential antimucositis agent in cancer patients

The antiinflammatory agent curcumin (diferuloylmethane) has a potential to mitigate cancer therapy-induced mucositis. We assessed the in vitro extent of its bactericidal activity and determined the kinetics of its antiinflammatory effect on pharyngeal cells. Bactericidal activity was assessed using the LIVE/DEAD® Kit after 4 h of exposure to curcumin (50-200 μM) in 18 oropharyngeal species commonly associated with bacteremia in febrile neutropenia. Moraxella catarrhalis or its outer membrane vesicles were used to determine the inhibitory effect of curcumin on bacteria-induced proinflammatory activity as determined by cytokine release into the supernatant of Detroit 562 pharyngeal cells using the Luminex® xMAP® technology. Curcumin exerted a concentration-dependent bactericidal effect on all 18 species tested. After 4 h at 200 μM, 12 species tested were completely killed. Preincubation of Detroit cells with 200 μM curcumin for 5 to 60 min resulted in complete suppression of the release of tumor necrosis factor-α, interleukin (IL)-6, IL-8, monocyte chemoattractant protein 1, granulocyte macrophage-colony stimulating factor, and vascular endothelial growth factor. Fibroblast growth factor-2 and interferon-γ were not affected. Repetitive exposure to curcumin resulted in repetitive suppression of cytokine/chemokine expression lasting from 4 to 6 h. Through reduction of oral microbial density as well as suppression of inflammation cascades curcumin may prevent cancer therapy-induced oral mucositis, e.g., when applied as multiple daily mouth washes.

Kinetics of the interaction of desAABB-fibrin monomer with immobilized fibrinogen

The soluble and stable fibrin monomer-fibrinogen complex (SF) is well known to be present in the circulating blood of healthy individuals and of patients with thrombotic diseases. However, its physiological role is not yet fully understood. To deepen our knowledge about this complex, a method for the quantitative analysis of interaction between soluble fibrin monomers and surface-immobilized fibrinogen has been established by means of resonant mirror (IAsys) and surface plasmon resonance (BIAcore) biosensors. The protocols have been optimized and validated by choosing appropriate immobilization procedures with regeneration steps and suitable fibrin concentrations. The highly specific binding of fibrin monomers to immobilized fibrin(ogen), or vice versa, was characterized by an affinity constant of approximately 10(-8)M, which accords better with the direct dissociation of fibrin triads (KD approximately 10(-8) -10(-9) M) (J. R. Shainoff and B. N. Dardik, Annals of the New York Academy of Science, 1983, Vol. 27, pp. 254-268) than with earlier estimations of the KD for the fibrin-fibrinogen complex (KD approximately 10(-6) M) (J. L. Usero, C. Izquierdo, F. J. Burguillo, M. G. Roig, A. del Arco, and M. A. Herraez, International Journal of Biochemistry, 1981, Vol. 13, pp. 1191-1196).