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Phospholipid molecules self-assemble to form bilayers that are poorly soluble in an aqueous solvent. Phospholipids may, however, be readily dissolved by mixing with a bile salt or amphiphilic drug surfactant that forms mixed surfactant/phospholipid micelles. Mixed bile salt/phospholipid micelles play an important role in the digestion of fats in the gastrointestinal tract as well as solubilizers of water-insoluble drugs and other drug delivery applications. The ability of surfactants to dissolve phospholipids largely depends on the chemical structure of both surfactant and phospholipid. While bile salt and amphiphilic drug surfactants, with a rigid chemical structure, are good solubilizers of phospholipids, conventional surfactants, with a flexible aliphatic hydrocarbon tail, are poor solubilizers. In addition, the chemical structure of phospholipids, such as tail lengths and charge number, or the fraction of a cosurfactant, for instance cholesterol, is expected to influence the ability to form mixed micelles. In this paper, the aggregation behaviour and mixed micelle formation of the phospholipid dimyristoyl phosphatidylglycerol (DMPC) and two different surfactants: the anionic surfactant sodium dodecyl sulfate (SDS) and the amphiphilic drug surfactant Sodium fusidate (SF, similar structure to that of bile salt), have been studied, and the transition from micelles to bilayers has  been determined for the different surfactants, as well as the size and structure of micelles and bilayers close to the points of transition. The self-assembly of the mixed micelles of surfactants/phospholipids have been investigated using surface tension measurements, refractive index increment and static and dynamic light scattering (SLS and DLS). The results suggest that the transition from micelles to bilayers are found to exist in the following range of bile salt/phospholipid compositions: For SF, 70-75 mol % phospholipid in the micelle was determined to be the point of transition, whilst 20-30 mol % for SDS. As the mole fractions of DMPC increased for both mixtures, the samples became turbid, which indicates the transition of micelles to bilayers. An exact value for molar ratio of transition might not be possible to determine from this study, but instead a, somewhat wider, range of values. In spite of this, a clear trend and difference between the two surfactants was observed.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20353号 / 工博第4290号 / 新制||工||1664(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 伊藤 禎彦, 准教授 松井 康人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Eine intrauterine Infektion ist eine ernstzunehmende Erkrankung mit möglicherweise schwerwiegenden Folgen für den Feten. Frühgeborene, die einer Chorioamnionitis ausgesetzt waren, haben jedoch eine geringere Mortalitätsrate mit biochemischen und strukturellen Veränderungen während der Lungenentwicklung. Vorhergehende experimentelle Arbeiten belegen die Initiierung einer Lungenreifung durch intraamniotisch verabreichtes Lipopolysaccharid. Hierbei wurde durch Aspiration der Amnionflüssigkeit eine fetale pulmonale Inflammationsreaktion in Gang gesetzt. Die Hypothese der vorliegenden Arbeit lautete, dass eine durch intravenös appliziertes Lipopolysaccharid induzierte fetale systemische Inflammation die intrauterine Lungenreifung ebenfalls beeinflusst. Die im Rahmen dieser Arbeit durchgeführten Versuche erfolgten an 21 fetalen Schafen mit einem Gestationsalter von 107 Tagen. Alle Tiere wurden zunächst mit intrauterinen Kathetern versehen. Nach einer Erholungsphase von 3 Tagen erhielten die Kontrolltiere (N=12) Kochsalzlösung und die Tiere der Versuchsgruppe (N=9) 100ng Lipopolysaccharid intravenös. Lungenstruktur und Lungenreifung der fetalen Schafe wurden mittels biochemischer und histologischer Untersuchungen nach 3 (N=5) und nach 7 (N=4) Tagen beurteilt. Die Infusion der Lipopolysaccharidlösung hatte zumindest innerhalb des Versuchszeitraums keinen Einfluss auf das Körpergewicht des Feten. Die systemische Entzündung trägt jedoch zu einer pränatalen Verletzung mit strukturellen pulmonalen Veränderungen bei. Sowohl eine Lungenreifung als auch eine gestörte strukturelle Lungenentwicklung traten nach einer kurzfristigen fetalen Inflammation ein. Die Konzentration an Interleukin-6 in der bronchoalveolären Lavage stieg 3 Tage nach Applikation des Lipopolysaccharids mehr als 40fach an. Sowohl die Prozessierung von Pro-Surfactant Protein (SP)-B zu reifem SP-B als auch erhöhte Konzentrationen an SP-B konnten nach 7 Tagen nachgewiesen werden. Ebenfalls war eine Steigerung des phosphorylierten STAT-3 im Lungengewebe zu erkennen. Die Ablagerung von Elastinfasern an Septierungsstellen der Alveolen wurde innerhalb von 3 Tagen nach Lipopolysaccharidapplikation negativ beeinflusst. Aus den Erkenntnissen dieser Arbeit könnten neue Therapieansätze sowohl für das Atemnotsyndrom des Frühgeborenen als auch der bronchopulmonalen Dysplasie resultieren, die eine Modulation der Entzündungsreaktion zum Ziel haben. Alle therapeutischen Ansätze werden einen Weg zwischen den positiven Effekten der Lungenreifung mit gesteigerter Compliance, reduzierter Alveolarwanddicke und vermehrtem prozessiertem SP-B und den schädlichen Einwirkungen auf die Lungenstruktur mit veränderter Elastinverteilung und kapillärer Leckage finden müssen. Bedauerlicherweise können die erhobenen Daten nicht klären, ob die einmalige Infusion von LPS eine anhaltende oder permanente Störung der alveolären Entwicklung hervorbringt. Die strukturellen Veränderungen des Lungengewebes, die denen einer BPD ähneln, lassen jedoch eine permanente Organschädigung befürchten. / Intrauterine infection is a serious condition with potentially severe consequences for the fetus. However, preterm infants exposed to chorioamnionitis have a lower mortality rate associated with biochemical and structural changes during lung development. Previous studies demonstrated the initiation of lung maturation by intraamniotically administered lipopolysaccharide. The fetal pulmonary inflammatory response was initiated by aspiration of amniotic fluid. The hypothesis of the present study was that fetal systemic inflammation induced by intravenously applied lipopolysaccharide would also influence intrauterine lung maturation. The experiments were performed on 21 fetal sheep at a gestational age of 107 days. All animals were instrumented with intrauterine catheters. After a recovery period of 3 days, the control animals (N=12) received saline and the animals in the study group (N=9) received 100ng lipopolysaccharide intravenously. Lung structure and lung maturation were assessed by biochemical and histological examinations after 3 (N=5) and 7 (N=4) days. Fetal body weight was not affected, at least within the experimental period. However, the systemic inflammation contributed to prenatal injury with structural pulmonary changes. Both lung maturation and impaired structural lung development occurred after short-term fetal inflammation. The concentration of interleukin-6 in the bronchoalveolar lavage increased more than 40-fold 3 days after application of lipopolysaccharide. Both processing of pro-surfactant protein (SP)-B to mature SP-B and increased concentrations of SP-B were detected after 7 days. Furthermore, an increase of phosphorylated STAT-3 in lung tissue occurred. Elastin deposition was negatively affected within 3 days after lipopolysaccharide application. The findings of this study may result in new therapeutic approaches for both respiratory distress syndrome and bronchopulmonary dysplasia that aim to modulate the inflammatory response. All therapeutic approaches will have to find a way between the beneficial effects of lung maturation with increased compliance, reduced alveolar wall thickness, and increased processed SP-B and the deleterious effects on lung structure with altered elastin deposition and capillary leakage. Regrettably, the data collected cannot clarify whether the single infusion of LPS results in persistent or permanent disruption of alveolar development. However, structural changes in lung tissue similar to those seen in BPD indicate permanent organ damage.

In this thesis, copolymer latexes comprised of various fractions of methyl methacrylate (MMA) and butyl acrylate (BA) were synthesized through surfactant-free emulsion polymerization. A carbon dioxide responsive comonomer, 2-(diethyl)aminoethyl methacrylate (DEAEMA) was also used with an equimolar amount of hydrochloric acid (HCl) to promote its partitioning into the water phase. Changing the MMA/BA fraction gave control over the resulting glass transition temperature of the particles. Following polymerization, the particles from the resulting latexes could be effectively coagulated be adding a small amount of caustic soda, and could be easily separated from water. After washing the particles with deionized water, CO2-redispersibility of the latex particles was evaluated as a function of their respective glass transition temperature. It was determined that coagulated particles higher in MMA content could be easily redispersed into carbonated water with the aid of ultrasonication, preparing stable latexes of the same solids content. For latex particles with a glass transition temperature below ambient conditions, coagulation led to the fusion of individual particles, which inhibited their ability to be redispersed. By conducting the coagulation and redispersion cycles at temperatures cold enough for the BA-rich particles to be below their glass transition temperature, these same latex particles could be effectively redispersed. The relationship between the glass transition temperature of the latexes and their CO2-redispersibility provides guidance from a practical sense for the applicability of CO2-sensitive amine-functionalized molecules in developing industrially useful CO2-redispersible latex products. / Thesis / Master of Applied Science (MASc) / This work examines special type of coagulatable and redispersible latex paint that could potentially reduce the costs in storing and transporting latex paint products. After synthesizing the latex, the nanoscopic polymer particles that make up the latex could be easily coagulated by adding a small amount of sodium hydroxide. Following this, water could be removed and a condensed form of the paint was obtained. The ability to redisperse the particles back into carbonated water was subsequently examined based on the softness of the polymer particles by synthesizing a series of latexes with different fractions of methyl methacrylate (MMA) and butyl acrylate (BA). After synthesis, the latexes that contained higher fractions of MMA were comprised of particles that were less soft than the BA-rich latexes, which made the redispersibility of these particles much easier. Upon coagulation, BA-rich particles fused together upon contact and could not be separated, hence inhibiting their redispersibility. When these same BA-rich latex particles were coagulated at colder temperatures, fusion was inhibited and the redispersibility of particles was greatly improved. Overall, the particles were found to be redispersible if the glass transition temperature of polymer chains within the particles was lower than ambient temperature. Since softer polymer particles are often used for latex paint-based applications, this work provides important and relevant insight in the development of industrially useful CO2-redispersible products.

Le processus de maturation pulmonaire implique entre autres la production d'un composé majoritairement lipidique : le surfactant. Cette étude réalisée du jour de gestation (JG) 15.5 au jour post-natal (PN) 10 a permis d'identifier dans le poumon murin les sites d'expression des apolipoprotéines (apo) A-I, A-Il, C-II, H et de la lipoprotéine lipase (LPL), gènes impliqués dans le métabolisme des lipides. On observe une co-localisation dans les cellules épithéliales des conduits respiratoires au JG 17.5 pour tous les messagers étudiés. Une co-localisation pour les protéines apoA-I, H et LPL est observée dans les capillaires. L'apoC-H est exprimée dans les cellules épithéliales distales tandis que l'apoA-II est retrouvée dans le mesenchyme. En période post-natale, l'expression de l'apoC-II et de la LPL se situe dans les conduits bronchiques et les macrophages. La localisation du site d'expression de ces gènes leur suggère un rôle dans la synthèse du surfactant.

Reducing atmospheric CO2, a main source of greenhouse gas, has been accentuated recently. One focus is capture, separation, and sequestration of industrial CO2. As a hydrate former, CO2 forms hydrates at moderate temperatures and pressures. This phenomenon could be utilized to capture and separate CO2 from flue gases, and also has the potential to sequester CO2 in the deep sds. This research investigated the CO2-N2 separation efficiency of gas hydrates; it investigated the sequestration potential of CO2 hydrates in ocean sediments. The catalytic effect of surfactants in these processes was investigated. A fluorosurfactant FS-62 was mixed with SDS at 100ppm/1000ppm was found to best catalyze CO2 hydrate formation, giving a high formation rate of 0.1239 mmole of occluded gas/minute-about 2.87 times the base case with no surfactant. FS-62/SDS was verified to increase the separation efficiency of N2-CO2 gas which formed a mixture gas hydrate. In a two-stage process, a desirable separation efficiency was obtained. A total CO2 removed from the gas mixture of 67.7% was obtained. In a series of experiments simulated under ocean sediment environments, the biosurfactants Emulsan and Rhamnolipid showed favorable catalysis of CO2 hydrate formation. Also, the chemical structure of the porous media was found to have some influence on the hydrate formation rate. For a quiescent system, the displacement of natural gas from hydrate by injecting CO2 occurred at a low level and would not be a practical process. In the case of displacing CH4 from hydrate with CO2, no displacement would occur. This research work showed that a potentially cost effective hydrate separation technology applied to N2-CO2 gas, representative of a flue gas, can be improved by adding surfactants. It was found that biosurfactants give some beneficial effect on CO2 hydrate formation in sediments and might be used to assist CO2 sequestration in sediments or to displace natural gas from hydrates already in sediments.

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