This dissertation describes the effects of tetrastarch (130/0.4) on serum colloid osmotic pressure and thromboelastography variables in healthy pony mares. Additional variables assessed during this study included markers of haemodilution (PCV, TS) and serum creatinine and bile acid concentrations. Six clinically healthy Nooitgedacht pony mares were utilized in a crossover study design. Tetrastarch (130/0.4) was administered at 10, 20 and 40 ml/kg bwt to each mare in a random sequence with a two week washout period between each of the treatments. Packed cell volume (PCV), plasma total solids (TS), serum colloid osmotic pressure (COP), and platelet count were measured and thromboelastography (TEG) was performed before treatment (baseline), immediately after infusion (time 0), and 1, 6, 12, 24, 48, and 96 h after tetrastarch infusion. All TEG variables remained within reference range in all treatment groups. Administration of tetrastarch at 40 ml/kg bwt resulted in a prolonged K-time at 6 h post-infusion, and decreased maximum amplitude at 0, 1, 6, 24 and 48 h post-infusion compared to baseline. Administration of tetrastarch increased mean COP values above baseline in all three treatment groups, persisting to 24, 6 and 48 h after treatment with 10, 20 and 40 ml/kg of tetrastarch respectively. This study concluded that, although values remained within established reference ranges, the administration of tetrastarch (130/0.4) at 40 ml/kg bwt is more likely to induce changes in TEG variables than doses of 20 ml/kg or less. Tetrastarch increased COP in healthy horses at all evaluated dose rates. / Dissertation (MMedVet)--University of Pretoria, 2014. / gm2014 / Companion Animal Clinical Studies / unrestricted

Chapter 1. Supramolecular Gels and their Applications Supramolecular gels are viscoelastic materials composed of a solid like three dimensional fibrillary network that is embedded in a liquid. Supramolecular gels are derived from low molecular weight compounds (typically MW < 3000). In the 1990s, the investigations on gels were mainly focused on designing new gelator molecules. However, during the last decade, research focus shifted towards designing functional gels and their applications. As a result of extensive work in this area, gels have been found to have varied applications in the templated synthesis of inorganic nanomaterials, hybrid materials, light harvesting systems, as responsive system and sensors, and also in drug delivery, tissue engineering etc. This chapter gives an introduction to supramolecular hydrogels/organogels and relevant bile acid chemistry touching upon the gelation properties of the bile acid derivatives. Diverse applications of the supramolecular gels are also illustrated with several examples. Scheme 1. Various applications of functional supramolecular gels Chapter 2. Bile Acid derived novel Hydrogelators Part 1. Hydrogelation of Bile acid protected Amino acids and Hybrid Materials Hydrogels from low molecular weight molecules have significant importance in biomedical applications. In this chapter, we report injectable hydrogel formation from bile acid conjugates of various amino acids. Hydrogel formation was found to be dependent on multiple factors such as bile acid backbone structure, linkage between the bile acid and the amino acid, pH etc. Single crystal structures of lithocholyl phenylalanine, lithocholyl-glycine, lithocholyl-L valine and lithocholyl-L alanine were also determined. Finally, the hydrogel frameworks were utilized to produce hybrid materials with Gold and ZnO nanoparticles. Scheme 2. (a) Crystal structure of LC-LF-OH gelator molecule, (b) photograph of gel, (c) SEM and (d) AFM image of LC-LF-OH xerogel Part 2. Hydrogelation of bile acid-dipeptide conjugates and in situ synthesis of silver and gold nanoparticles in the hydrogel matrix Fabricating supramolecular hydrogels with embedded metal nanostructures are important for the design of novel hybrid nanocomposite materials for diverse applications such as bio sensing and chemo sensing platforms, catalytic and antibacterial functional materials etc. Supramolecular self-assembly of bile acid-dipeptide conjugates have led to the formation of new supramolecular hydrogels. Gelation of these molecules depends strongly on the hydrophobic character of the bile acids. Ag+ and Au3+ salts were incorporated in the hydrogels, and photo reduction and chemical reduction led to the in situ generation of Ag and Au NPs in these supramolecular hydrogels without the addition of any external stabilizing agent. The color, size and shape of silver nanoparticles formed by photo reduction depended on the amino acid residue on the side chain. Furthermore, the hydrogel-Ag nanocomposite was tested for its antimicrobial activity. Scheme 3. Bile acid based dipeptide hydrogelators and soft hybrid materials Chapter 3. Sonogels of bile salts of In(III): use in the formation of self-templated indium sulfide nanostructures In this chapter, facile hydrogel formation by Indium(III) cholate and deoxy cholate are reported. When In(III) solution was added to aqueous solutions of sodium cholate and sodium deoxy cholate and sonicated, the mixtures formed gels. The gels thus obtained were translucent/turbid and thermos irreversible. Rheological measurements showed that all of them could be classified as viscoelastic soft solids. Scanning electron microscopy and atomic force microscopy showed typical entangled three dimensional fibrous networks. The In-Ch hydrogel were further used to prepare nanostructured In2S3 in which the cholate units possibly acted as a surfactant to confine the growth of the Nano flakes. Scheme 4. In-Ch hydrogel (Photograph and SEM image of In-Ch gel) Chapter 4. Palladium-Hydrogel Nanocomposite for C-C Coupling Reactions Supported metallic nanoparticles are important composite materials owing to their enormous potential for applications in various fields. This chapter describes the in situ formation of palladium nanoparticles in a calcium-cholate (Ca-Ch) hydrogel by reduction with sodium cyan borohydride. The hydrogel matrix appeared to assist the controlled growth as well as stabilization of palladium nanoparticles. The palladium nanoparticle/Ca-Ch hydrogel hybrid was characterized by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Furthermore, PdNP/Ca-Ch hybrid xerogel was shown to act as an active catalyst for Suzuki reaction under aqueous aerobic conditions, up to 4 cycles. This PdNP/Ca-Ch xerogel retained its catalytic activities on storage for several months. Scheme 5. Palladium-hydrogel nanocomposite for C-C coupling reactions in water Chapter 5. Sensitization of Terbium/Europium in self-assembled cholate hydrogel: An approach towards the detection of amine vapours "Luminescent" lanthanides have intrinsic low molar absorptivity, although this problem can be addressed by complexing the lanthanide ion with suitable chelating ligands which improve the luminescence properties drastically. However the design of such systems often involves careful planning and laborious synthetic steps. It is therefore desirable to have a simpler way to sensitize lanthanides with high efficiency. It was observed in our group that trivalent lanthanides formed hydrogels on the addition of sodium cholate. This chapter describes the discovery of the several biphenyl derivatives (such as 4-biphenylcarbaxaldehyde, 4-acetylbiphenyl) for sensitization of Tb(III) and Eu(III) in lanthanide hydrogels. Sensitization of Tb(III) and Eu(III) were observed by doping was characterized by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Furthermore, PdNP/Ca-Ch hybrid xerogel was shown to act as an active catalyst for Suzuki reaction under aqueous aerobic conditions, up to 4 cycles. This PdNP/Ca-Ch xerogel retained its catalytic activities on storage for several months. Scheme 6. Schematic representation of the sensitization process (the arrangement of themolecules in the gel fiber is arbitrary)(For figures pl refer the abstract pdf file)

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.

The Shigella species cause millions of cases of watery or bloody diarrhea each year in developing countries, with children under the age of five years most vulnerable to infection. Emerging strains of multidrug resistant Shigella emphasize the need for a comprehensive and cost-efficient vaccine; however, an effective vaccine has yet to be produced despite years of research. Several studies have demonstrated that Shigella utilizes host physiology, specifically bile salts as signals for invasion and virulence gene expression. This study aimed to build upon previous research analyzing the bile salts transcriptional profile of Shigella flexneri 2457T, in which an induction of the uncharacterized gene was demonstrated during bile salts exposure. Here, a mutant and wild-type 2457T strains were used in infection of HT-29 colonic epithelial cells to compare invasion ability and intracellular replication. The Congo red (CR) secretion assay was also used as a measure of virulence protein secretion from the type-III secretion system (T3SS), while interleukin-8 (IL-8) secretion from infected HT-29 cells was measured as a marker for the epithelial cell response to infection. Infection analyses included subculturing the strains in media with 0.4% bile salts to mimic small intestine physiology and gastrointestinal transit of S. flexneri prior to infection. The mutant strain displayed both increased invasion of and intracellular replication in HT-29 cells compared to 2457T. The presence of bile salts enhanced both invasion and intracellular replication in both strains when compared to wild-type without bile salts exposure during subculture. The CR assays revealed increased protein secretion from the mutant compared to 2457T, and that bile salts increased T3 secretion in both strains. Increased IL-8 secretion from infected HT-29 cells was detected when both strains were subcultured in bile salts; however, a decrease in IL-8 secretion was observed following infection with the mutant subcultured without bile salts. Overall, the data suggest that this bile salt-induced gene encodes a negative regulator of virulence, and that the gene product likely prevents a hypervirulence phenotype that would compromise the ability of S. flexneri to control infection and regulate the host immune response. This work has provided insights into the function of this uncharacterized gene, which could serve as a novel target for future therapeutic development. / 2027-06-30T00:00:00Z

Indiana University-Purdue University Indianapolis (IUPUI) / Primary Sclerosing Cholangitis (PSC) is a rare and slow progressing cholangiopathy characterized by hepatic inflammation, fibrosis and ductular reaction with liver transplantation as the sole therapeutic option. PSC patients are at high risk of auto-immune comorbidities like irritable bowel disease (IBD), found in up to 80% of PSC patients (PSC-IBD). There are indications of genetic and environmental components for auto-immune development in IBD; however, its etiology remains unclear. Mast cells (MCs) infiltrate the liver and can become activated leading to degranulation and release of mediators, like histamine (HA), which result in increased intrahepatic bile duct mass, biliary senescence, hepatic inflammation, and hepatic stellate cell activation. Similarly, MCs infiltrate the intestine and increase inflammation which alters host-microbiome communication. MCs are necessary for successful liver regeneration and the combat of intestinal pathogens; however, chronic HA signaling exacerbates damage in cholangiopathies and IBD. Bile acid synthesis is tightly regulated by Farnesoid X Receptor (FXR) and its downstream mediator, fibroblast growth factor 15 (FGF15, -19 in humans). Cholangiocytes (i) are the target of cholangiopathies, (ii) modify and recycle bile acids through Apical Sodium Bile Acid Transporter (ASBT)-mediated cholehepatic shunting, which functions outside of enterohepatic circulation of bile acids and (iii) are capable of autocrine HA signaling. The complex relationship between hepatic and intestinal MC infiltration and bile acid signaling has not been established; therefore, identifying MC regulation of bile acid pool and FXR/FGF15 signaling pathway will provide insight into therapeutic treatment of PSC-IBD. Under the rationale that (i) cholestatic liver diseases are positively correlated with auto-immune comorbidities like IBD, (ii) during disease, MCs infiltrate the liver and intestine and release signaling factors like HA, and (iii) MCs express FXR and secrete FGF15/19; we propose the central hypothesis that MC activation regulates bile acid signaling and PSC progression through paracrine crosstalk with cholangiocytes in the liver and intestinal inflammation.

The Shigella species are Gram-negative enteropathogens that produce severe diarrhea, cramping, and dehydration in millions of people annually. The pathogens most commonly infect children under the age of 5 years in developing nations, where the rise of multidrug-resistant species is increasingly problematic. Despite several attempts to develop a vaccine against these pathogens, no successful vaccine has been produced. In order to achieve this goal, several characteristics of Shigella must be further elucidated. Namely, we must better understand the mechanisms Shigella employs in order to circumvent the immune response. A key way in which Shigella circumvents the innate defenses of the host is through resistance to bile salts, the principal component of bile, a substance found in the small intestine that is required for digestion. One such bile salt resistance mechanism of Shigella involves lipopolysaccharide (LPS), an extracellular structure composed of three regions: a transmembrane lipid, a polysaccharide core, and an O-antigen. LPS and LPS modifications have been implicated in bile salts resistance in other enteropathogens. Thus, the goal of this study was to build from preliminary findings to understand the role of LPS in conferring bile salts resistance in Shigella. Two Shigella flexneri mutants were studied to understand the roles of the polysaccharide core and O-antigen on bacterial growth and LPS modifications during exposure to bile salts. Growth comparisons of the mutants relative to wild type bacteria in the presence of bile salts were performed, including analysis of growth with exposure to bile salts and with varying levels of environmental glucose. Additionally, LPS was extracted from wild type and mutant bacteria grown in these conditions for analysis by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE). The growth curves demonstrated that both the O-antigen and polysaccharide core mutants exhibited slow growth with exposure to bile salts, while the SDS-PAGE analyses revealed changes in the LPS profile of wild type and both LPS mutants when grown in bile salts. These data indicate that the O-antigen likely has an important role in conferring bile salts resistance and that the polysaccharide core may also facilitate resistance. This study allows us to better understand how LPS contributes to bile salts resistance in S. flexneri, which may enhance efforts to develop an effective vaccine against this pathogen. / 2023-12-10T00:00:00Z

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19580号 / 医博第4087号 / 新制||医||1013(附属図書館) / 32616 / 京都大学大学院医学研究科医学専攻 / (主査)教授 妹尾 浩, 教授 木村 剛, 教授 柳田 素子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Hepatobiliary disease can sometimes be difficult to diagnosis due to non-specific clinical signs, and diagnostic imaging is a vital tool in diagnosing these diseases. Multi-slice computed tomographic cholangiography (MSCTC) is a non-invasive way to obtain high quality images of the hepatobiliary system. Our objectives were to determine the best technique for performing MSCTC in normal dogs with regards to contrast agent, dose, and optimal time to imaging. Our test subjects included eight normal adult hounds. Four dogs were administered Cholografin and the other four Biliscopin. Two dose groups were established with four dogs receiving 0.5mL/kg and four receiving 1 mL/kg. Our results demonstrated that MSCTC is feasible in normal dogs and produces high quality images of the hepatobiliary system. The contrast agent Biliscopin at the higher dose subjectively produced the best quality images. The optimal time to image patients following contrast administration varied between contrast agents (15-60 minutes).

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a widely used class of drugs, due in part to the effective anti-inflammatory and analgesic properties they exhibit. Unfortunately, NSAIDs also exhibit substantial gastrointestinal (GI) toxicity. The mechanisms underlying the ability of NSAIDs to cause ulceration in the stomach and proximal duodenum are well understood, and this injury can largely be prevented through the suppression of gastric acid secretion by proton pump inhibitors (PPIs) or histamine H2 receptor antagonists (H2RAs). In contrast, the pathogenesis of small intestinal injury induced by NSAIDs (i.e., NSAID-enteropathy) is poorly understood, and there are no proven-effective therapies. This is a major clinical concern as NSAID-induced enteropathy and bleeding occur more frequently than NSAID-induced gastropathy, and is associated with significantly higher rates of morbidity and mortality. There is clear evidence that indicates important contributions to NSAID-enteropathy by bile, enteric bacteria, and the enterohepatic circulation of NSAIDs. However, it is not clear which of these mechanisms is/are the primary driver(s) of intestinal damage and injury. There is also evidence that hydrogen sulfide (H2S) can protect the GI mucosa from ulceration and reduce the severity of NSAID-induced GI damage, although the mechanisms of H2S-induced intestinal protection remain to be determined. Therefore, the central aim of this thesis was to evaluate the roles of bile, enteric bacteria, and the enterohepatic circulation of NSAIDs in the pathogenesis of NSAID-enteropathy, and to investigate the ability of H2S to protect the small intestine from NSAID-induced damage. Chapter 1 is an introduction to the relevant literature and Chapter 2 is an outline of the thesis scope and objectives. In Chapter 3, I demonstrated that the co-administration of an H2S-releasing agent protected rats from NSAID-induced enteropathy, in part by preventing NSAID-induced dysbiosis and bile cytotoxicity. In Chapter 4 and 5, I established that the co-administration of PPIs and H2RAs exacerbated NSAID-enteropathy in part by causing intestinal dysbiosis and enhanced bile cytotoxicity. Lastly, I demonstrated that the small intestine-sparing effects of an H2S-releasing NSAID, ATB-346, are partly attributable to the reduced enterohepatic circulation of ATB-346 or the naproxen liberated from this drug (Chapter 5). In summary, the work presented in this thesis provided novel understanding of the complicated pathogenesis of NSAID-enteropathy by confirming that the nature of the bile, the enterohepatic circulation of NSAIDs, and the nature of the intestinal microbiota are of paramount importance. In addition, the results also demonstrated that hydrogen sulfide represents an effective preventative therapy for NSAID-enteropathy and that H2S-releasing NSAIDs, such as ATB-346, have remarkable preclinical safety. / Thesis / Doctor of Philosophy (PhD)

Obesity is considered to be a worldwide epidemic disease characterized by an accumulation of AT. Increased adiposity can perturb normal metabolic functions and lead to the development of diseases like insulin resistance and other metabolic disorders. A large amount of clinical studies have been shown that changes in inflammatory signaling in adipose tissue cells, increased infiltration of immune cells into AT as well as stress of endoplasmic reticulum belong to the key molecular steps leading to the development of metabolic disturbances associated with this disease. Adverse metabolic effects of AT accumulation can be diminished by calorie restriction resulting in weight loss. In addition, stress of endoplasmic reticulum could be alleviated by chemical chaperones including bile acids. These two approaches for the treatment of obesity or the obesity-associated disturbances were basis for this PhD thesis. In the first part of this work, we studied inflammation status of gluteal in comparison with abdominal AT and differentiation and secretory capacity of adipocytes after weight loss in obese patients. We revealed that inflammatory profile of gluteal AT, estimated by mRNA level of macrophages and cytokines as markers of inflammatory status of the body, did not explain the different clinical impact of...