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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
211

The Effects of Acid-Base Parameters, Oxygen and Heparin on the Ability to Detect Changes in the Blood Status of End-Stage Renal Disease Patients Undergoing Hemodialysis Using Whole Blood-Based Optical Spectroscopy

Atanya, Monica January 2011 (has links)
Relative changes are detectable in the blood of end-stage renal disease (ESRD) patients during hemodialysis (HD) treatment using optical spectroscopy. However, the potential impacts of several confounding factors that could affect the detection of these changes have not been evaluated. The objectives of this thesis were to: 1) investigate how the variations and/or changes in acid-base and oxygen parameters during HD treatment can affect the optical signature of whole blood of ESRD patients, 2) to investigate the effect of heparin on the optical properties of whole blood and its impact on our method. Blood samples were drawn from 23 ESRD patients at 5 time points during a 4 hour HD treatment and sent for blood gas and blood spectroscopy analyses. No significant correlations were found between the changes in the blood transmittance spectra and acid-base and oxygen parameters. This indicates that the perturbations in these parameters due to HD procedures do not confound the detection of changes in the blood transmittance spectra of ESRD patients during HD treatment. Additionally, the effect of heparin in modifying the optical properties of whole blood does not confound the detection of changes in the blood of ESRD patients due to HD treatment using whole blood-based optical spectroscopy. ANOVA revealed significant (P<0.05) measurable changes in the blood transmittance spectra of ESRD patients during HD treatment. Significant spectral differences (P<0.05) were found between ESRD patients. The lack of uniform spectral characteristics across patients is
212

Raman Biosensors

Ali, Momenpour January 2017 (has links)
This PhD thesis focuses on improving the limit of detection (LOD) of Raman biosensors by using surface enhanced Raman scattering (SERS) and/or hollow core photonic crystal fibers (HC-PCF), in conjunction with statistical methods. Raman spectroscopy is a multivariate phenomenon that requires statistical analysis to identify the relationship between recorded spectra and the property of interest. The objective of this research is to improve the performance of Raman biosensors using SERS techniques and/or HC-PCF, by applying partial least squares (PLS) regression and principal component analysis (PCA). I began my research using Raman spectroscopy, PLS analysis and two different validation methods to monitor heparin, an important blood anti-coagulant, in serum at clinical levels. I achieved lower LOD of heparin in serum using the Test Set Validation (TSV) method. The PLS analysis allowed me to distinguish between weak Raman signals of heparin in serum and background noise. I then focused on using SERS to further improve the LOD of analytes, and accomplished simultaneous detection of GLU-GABA in serum at clinical levels using the SERS and PLS models. This work demonstrated the applicability of using SERS in conjunction with PLS to measure properties of samples in blood serum. I also used SERS with HC-PCF configuration to detect leukemia cells, one of the most recurrent types of pediatric cancers. This was achieved by applying PLS regression and PCA techniques. Improving LOD was the next objective, and I was able to achieve this by improving the PLS model to decrease errors and remove outliers or unnecessary variables. The results of the final optimized models were evaluated by comparing them with the results of previous models of Heparin and Leukemia cell detection in previous sections. Finally, as a clinical application of Raman biosensors, I applied the enhanced Raman technique to detect polycystic ovary syndrome (PCOS) disease, and to determine the role of chemerin in this disease. I used SERS in conjunction with PCA to differentiate between PCOS and non-PCOS patients. I also confirmed the role of chemerin in PCOS disease, measured the level of chemerin, a chemoattractant protein, in PCOS and non-PCOS patients using PLS, and further improved LOD with the PLS regression model, as proposed in previous section.
213

Synthetic approaches towards heparinoid related saccharides and derivatives

Broberg, Karl Rufus January 2011 (has links)
Heparin glycosaminoglycans mediate a range of biological events, including anticoagulation as well as a diversity of cell proliferation and differentiation processes. Heparin saccharides have been shown to act as inhibitors against angiogenesis and metastasis of tumour cells. This thesis describes work developing chemistry towards varying length oligosaccharide sequences with potential to offer variable sulfation patterns. The main synthetic components to this work were contribution to developing scalable syntheses of an orthogonally protected L-Iduronic acid unit and a differentially protected D-glucosamine unit. The synthetic work also evaluated a recently reported diazo transfer reagent, which allowed for earlier placement of azide protection over that of previously developed routes within the group. This provided a cheaper, more atom efficient route towards protected D-glucosamine building blocks. Glycosylation of the developed D-GlcN donor units with the L-Ido acceptor allowed the production of key disaccharides which facilitated an efficient iterative glycosylation strategy towards longer oligosaccharides, ultimately providing a differentially protected pentasaccharide. The project evaluated methods towards generating various dimeric heparin type systems through forming new O4 ether linkages between GlcN residues across various short linker fragments. The most successful of these dimerisations used a methallyl dichloride core which allowed for further derivatisation towards dihydroxylated species, the analysis of which highlighted some interesting proton NMR data. The final aspect of this project began development of chemistry towards non-reducing end-labelled oligosaccharide sequences by implementation of a masked aldehyde unit on the C4 hydroxyl of GlcN synthesised from the allylated GlcN precursor via dihydroxylation chemistry. Incorporation of this moiety (protected as a 1,2-dibenzyl glycol) within both a trisaccharide and a pentasaccharide was achieved. Further development of this chemistry should allow for late step oxidative cleavage to reveal the reactive aldehyde, potentially allowing for attachment of various amine functionalised fluorophores via reductive amination. Radiolabelling of such a species should also be possible through sodium borotritide reduction for example.
214

Nouvelle voie d'accès à des dérivés de l'acide L-iduronique / New route to L-iduronic acid derivatives

Salamone, Stéphane 05 July 2010 (has links)
Le but de ce travail est la mise au point d'une nouvelle voie de synthèse de dérivés de l'acide L-iduronique, une sous-unité saccharidique constitutive des glycosaminoglycanes comme l'héparine. Les substrats de départ utilisés pour cette synthèse sont des dérivés du glucose, un sucre abondant et bon marché. Nous avons étudié, l'inversion de configuration en C-5 permettant de passer d'un dérivé D-gluco à un dérivé L-ido. La première partie de ce travail porte donc sur les différentes étapes conduisant à l'inversion de configuration. La seconde partie est consacrée à l'obtention de divers dérivés d'acide L-iduronique obtenus par la suite de réactions précédemment mises au point, ainsi qu'à une optimisation des rendements de la synthèse mise au point. / The aim of this work is the conception of a new synthetic approach to L-iduronic acid derivatives, a saccharidic sub-unit part of glycosaminoglycans like heparin. The starting materials used for this synthesis are glucose derivatives, a cheap and abundant sugar. The strategy of the synthesis was to obtain an L-ido derivative from a D-gluco one, by performing an inversion of configuration at position 5. The first part of this work deals with the different reactions leading to the inversion of configuration. The second part concerns the way to obtain L-iduronic acid derivatives by the above studied reactions along with synthesis optimisation
215

Evaluation d'un variant d'antithrombine dans différentes indications thérapeutiques / Study of antithrombin variant in different therapeutic indications

Bourti, Yasmine 14 November 2016 (has links)
Notre équipe s’intéresse à la relation structure-fonction d’une protéine, l’antithrombine (AT), un inhibiteur physiologique de la coagulation, en vue d’un développement thérapeutique. Cette protéine anticoagulante, capable de lier un motif pentasaccharidique sur les dérivés hépariniques, possède en outre, à fortes concentrations (500%), des propriétés anti-inflammatoires médiées par sa liaison aux héparan-sulfates cellulaires. Ce profil a mené à l’évaluation de l’AT dans des situations associant un emballement de la coagulation et de l’inflammation, comme c’est le cas au cours du sepsis sévère et d’autres situations d’ischémie-reperfusion (I/R). Cependant, les fortes concentrations utilisées dans les études précliniques nécessiteraient d’administrer des doses d’AT incompatibles avec le profil de sécurité de cette protéine anticoagulante.Dans ce contexte, nous avons, au cours de ce travail, caractérisé un variant d’AT (AT-N135Q-Pro394) dépourvu d’activité anticoagulante et doué d’une affinité augmentée pour l’héparine. Ce variant est capable de piéger des dérivés hépariniques et apparait comme un candidat idéal pour une utilisation comme antidote en cas de surdosage en héparine non fractionnée (HNF), héparines de bas poids moléculaire (HBPM) ou fondaparinux. Par ailleurs, ce variant pourrait être utilisé à des doses cytoprotectrices, sans risque hémorragique.Afin de tester cette dernière hypothèse, nous avons développé un modèle d’I/R rénale chez la souris, qui s’accompagne d’une augmentation significative de marqueurs de dysfonction rénale (Urée, Créatinine, Kim-1) et de l’inflammation (expression tissulaire de cxcl-1, il-6). L’AT avait déjà été montrée protectrice (Mizutani et al, Blood 2003) dans un modèle murin comparable. De façon surprenante, nous n’avons observé aucun des effets protecteurs décrits, ni sur l’inflammation ni sur la fonction rénale, et que ce soit avec de l’AT plasmatique, de l’AT recombinante ou encore avec un mélange équimolaire d’AT latente et native. Ce même modèle nous a pourtant permis de mettre en évidence les effets nephroprotecteurs et anti-inflammatoires d’une autre protéine anticoagulante, la protéine C activée. Ces résultats décevants font écho à la rétractation pour fraude de l’article de Mizutani et al. en 2013. Le travail approfondi que nous avons mené nous permet de clarifier la littérature et d’affirmer que l’AT, d’origine plasmatique ou recombinante, ne possèdent pas d’effet protecteur dans l’I/R rénale chez la souris. Dans ces conditions, le variant AT-N135Q-Pro394 n’a pas été testé.Concernant la seconde indication, l’AT-N135Q-Pro394 avait déjà été évaluée in vivo comme antidote aux dérivés hépariniques, HNF, HBPM et fondaparinux, avec d’excellents résultats. Néanmoins, cet effet antidote a été exploré spécifiquement par mesure de l’activité anti-facteur Xa alors que l’AT inhibe plusieurs enzymes de la cascade de coagulation tel que les facteurs VIIa, IXa et IIa. Nous avons donc exploré cet effet antidote dans un test plus global de la coagulation, le test de génération de thrombine (TGT) pour pouvoir le comparer aux autres stratégies non spécifiques utilisées pour antagoniser les dérivés hépariniques (facteur VII activé recombinant, concentré de complexes prothrombiques activés ou protamine). De façon intéressante, dans un plasma mimant un surdosage, notre variant présente un effet antidote supérieur aux agents hémostatiques et au sulfate de protamine vis-à-vis du fondaparinux et des HBPMs, respectivement, et équivalent au sulfate de protamine vis-à-vis de l’HNF. Enfin, dans du plasma en l’absence d’anticoagulant, l’AT-N135Q-Pro394 ne montre aucun effet sur la génération de thrombine contrairement aux agents hémostatiques et au sulfate de protamine qui, ajoutés seuls dans du plasma, modifient significativement le profil des TGT / Our team topic focuses on the structural-function relationship of a natural anticoagulant, antithrombin (AT), in order to develop potential therapeutic agents. AT inhibits several serine proteases of the coagulation cascade and its inhibitory activity is increased when AT binds to a pentasaccharidic motif contained within in the heparin derivatives. At high concentrations (500%), AT also exerts anti-inflammatory and cytoprotective properties through its binding to heparan sulfate proteoglycans, making it a good candidate for supportive therapy in clinical settings associating inflammation and coagulation activation. Indeed, AT has already been evaluated in vivo in various models of ischemia-reperfusion injury (IRI) and AT even reached a large-scale clinical trial in severe sepsis. However, the high concentrations of AT that are needed to exert anti-inflammatory properties are inconsistent with the safety profile of this anticoagulant protein.In this context we have further characterized an AT variant (AT-N135Q-Pro394) with increased affinity to heparin but devoid of anticoagulant activity. Indeed, this variant was described to be able to trap heparin derivatives and our work was to pursue the characterization of this variant as an antidote toward heparin derivatives in clinical situations of overdosing. In addition, this AT variant binds to heparan sulfate proteoglycans with higher affinity, as compared to native AT, and appears as a promising cytoprotective agent whose administration would not be associated with any bleeding risk.To test the latter hypothesis, we developed a murine model of renal IRI in which the renal function was severely impaired, as attested by increased kidney injury markers (urea, creatinine, kim-1) and local kidney inflammation (renal gene expression of il-6 and cxcl-1). Indeed, in 2003, Mizutani et al. reported a protective effect of AT in a similar murine model of renal IRI. Surprisingly, we observed none of the described protective effects, neither on inflammation nor renal function, with plasma AT, recombinant AT and an equimolar mixture of native and latent AT. Nevertheless, the same model enabled us to highlight the nephroprotective and anti-inflammatory properties of another anticoagulant protein, activated protein C (APC), as previously reported. These disappointing results coincided with the withdrawal in 2013 of the study of Mizutani et al., and our work allowed us to clarify the literature and to claim that neither recombinant nor plasma-derived native nor latent forms of AT exhibit a protective effect in renal IRI in mice. Under these conditions, AT-N135Q-Pro394 variant has not been tested in our model.AT-N135Q-Pro394 has also been previously shown to efficiently neutralise the anticoagulant activity of heparin derivatives, including unfractionated heparin (UFH), low molecular weight heparins (LMWH) and fondaparinux in vivo. Nevertheless, this reversal effect was only explored by anti-factor Xa assays whereas AT inhibits a number of coagulation proteases, including factors VIIa, IXa and IIa. Therefore, we explored AT-N135Q-Pro394 variant in a more global coagulation assay, the thrombin-generation assay (TGA), in order to compare its activity with non-specific reversal agents used toward heparin derivative overdose (recombinant-activated factor VII, activated prothrombin-complex concentrate or protamine). Interestingly, in plasma mimicking an overdose, our variant demonstrated greater reversal efficiency as compared to hemostatic agents and protamine sulfate toward fondaparinux and LMWH, respectively, and was as efficient as protamine sulfate toward UFH. Finally, when added to native plasma (in the absence of heparin derivative), AT-N135Q-Pro394 showed no effect on thrombin generation unlike hemostatics and protamine sulfate that all significantly affect the TGA profile
216

Recombinant Human Mast-Cell Chymase: An Improved Procedure for Expression in Pichia Pastoris and Purification of the Highly Active Enzyme

Lockhart, Brent E., Vencill, Jessica R., Felix, Cherise M., Johnson, David A. 01 February 2005 (has links)
Human mast-cell chymase (EC 3.4.21.39) is a chymotrypsin-like serine protease that is stored in and released from mast-cell granules. This enzyme has been expressed in Pichia pastoris by homologous recombination of the cDNA coding for the mature active chymase into the Pichia genome. Cells producing the highest levels of recombinant human chymase were selected by activity screening and they were grown in a fermentor. Methanol induction resulted in the secretion of active chymase into the Pichia growth media and increasing levels of enzyme were detected in the media for 5 days. Active enzyme was purified from the culture media with a 22 % yield of activity by a simple two-step procedure involving hydrophobic-interaction chromatography followed by affinity chromatography on immobilized heparin. The major peak from the heparin column contained a single band of 30.6 kDa on SDS/PAGE. The purified recombinant human chymase was 96% active and the yield was 2.2 mg/l of growth media.
217

Development of heparin nanoparticles:synthesis, physicochemical/biochemical characterization and application to arthritis therapy / ヘパリンナノ粒子の開発:合成、物理化学的・生物学的評価と関節炎治療への応用

Hasan Babazada 24 September 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(薬学) / 甲第18549号 / 薬博第811号 / 新制||薬||238(附属図書館) / 31449 / 京都大学大学院薬学研究科医療薬科学専攻 / (主査)教授 橋田 充, 教授 髙倉 喜信, 教授 佐治 英郎 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM
218

Biochemical Analysis on the Interaction of Human Matrix Metalloproteinase 7 and Thermolysin with 8-Anilinonaphthalene 1-Sulfonate, Heparin, and Cholesterol Sulfate / ヒトマトリックスメタロプロテイナーゼ7およびサーモライシンと8-アニリノナフタレン-1-スルホン酸、ヘパリンおよびコレステロール硫酸の相互作用に関する生化学的解析

VIMBAI, NETSAI CHARITY SAMUKANGE 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19017号 / 農博第2095号 / 新制||農||1029(附属図書館) / 学位論文||H27||N4899(農学部図書室) / 31968 / 京都大学大学院農学研究科食品生物科学専攻 / (主査)教授 保川 清, 教授 安達 修二, 教授 入江 一浩 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
219

Bivalirudin Versus Heparin During Intervention in Acute Coronary Syndrome: A Systematic Review of Randomized Trials

Bhogal, Sukhdeep, Mukherjee, Debabrata, Bagai, Jayant, Truong, Huu T., Panchal, Hemang B., Murtaza, Ghulam, Zaman, Mustafa, Sachdeva, Rajesh, Paul, Timir K. 01 January 2020 (has links)
Introduction: Bivalirudin and heparin are the two most commonly used anticoagulants used during Percutaneous Coronary Intervention (PCI). The results of Randomized Controlled Trials (RCTs) comparing bivalirudin versus heparin monotherapy in the era of radial access are controversial, questioning the positive impact of bivalirudin on bleeding. The purpose of this systematic review is to summarize the results of RCTs comparing the efficacy and safety of bivalirudin versus heparin with or without Glycoprotein IIb/IIIa Inhibitors (GPI). Methods: This systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses PRISMA statements for reporting systematic reviews. We searched the National Library of Medicine PubMed, Clinicaltrial.gov and the Cochrane Central Register of Controlled Trials to include clinical studies comparing bivalirudin with heparin in patients undergoing PCI. Sixteen studies met inclusion criteria and were reviewed for the summary. Findings: Several RCTs and meta-analyses have demonstrated the superiority of bivalirudin over heparin plus routine GPI use in terms of preventing bleeding complications but at the expense of increased risk of ischemic complications such as stent thrombosis. The hypothesis of post-PCI bivalirudin infusion to mitigate the risk of acute stent thrombosis has been tested in various RCTs with conflicting results. In comparison, heparin offers the advantage of having a reversible agent, of lower cost and reduced incidence of ischemic complications. Conclusion: Bivalirudin demonstrates its superiority over heparin plus GPI with better clinical outcomes in terms of less bleeding complications, thus making it as anticoagulation of choice particularly in patients at high risk of bleeding. Further studies are warranted for head to head comparison of bivalirudin to heparin monotherapy to establish an optimal heparin dosing regimen and post-PCI bivalirudin infusion to affirm its beneficial effect in reducing acute stent thrombosis.
220

INVESTIGATION OF THE PATHOLOGICAL EFFECTS OF EXTRACELLULAR DNA AND HISTONES IN SEPSIS

MEDEIROS, SARAH K January 2023 (has links)
Sepsis is defined as a life-threatening organ dysfunction that results in systemic activation of coagulation and inflammation in response to microbial infection. Neutrophil extracellular traps (NETs) have shown to be an important interface between innate immunity and coagulation in sepsis. The major structural components of NETs are nucleosomes (DNA-histone complexes). Although nucleosomes do not modulate coagulation, there are conditions where DNA and histones dissociate from each other in the circulation (e.g. in the presence of heparan sulfate or therapeutic heparin binding histones, or DNase digestion of DNA). In vitro, purified DNA was reported to activate coagulation, but this procoagulant activity has been questioned due to isolation methods that yield DNA that is contaminated with other procoagulant molecules. On the other hand, histones have been shown to not only activate coagulation but are cytotoxic to endothelial cells. However, their contribution to the pathogenesis of sepsis has yet to be determined in an in vivo model. Understanding the contribution of DNA, histones, and nucleosomes to the pathogenesis of sepsis may allow us to develop novel therapies that may prove targeting multiple components of NETs (i.e. DNA and histones) may be beneficial. Consequently, in this thesis, we (1) identified methods of DNA purification that produce DNA that is free of contamination and confirmed the procoagulant properties of the isolated DNA, (2) determined the harmful effects of DNA, histones, and nucleosomes cytotoxicity, coagulation, and inflammation in vitro and in vivo, (3) and then we explored the possibility of targeting both DNA and histones using a combination approach of DNase I and heparin in a mouse model of sepsis. Since heparin is administered to patients as a thromboprophylaxis and DNase I is a potential therapy in sepsis, it is important to understand any potential drug-drug interactions. / Thesis / Doctor of Philosophy (PhD) / Sepsis is a type of blood poisoning that occurs when the body has an over reactive response to an infection. This can lead to tissue damage, organ failure, and death. Sepsis is recognized as a global health priority. The death rate from sepsis is high between 15% to 30%, suggesting that an improved understanding of how sepsis leads to death may develop into new therapies. Recently, it was discovered that high levels of free-floating DNA and histones in the blood can predict death in sepsis. The DNA and histones are likely released by white blood cells in response to trying to fight off the infection. In test tubes, free-floating DNA can trigger clotting of blood. DNA often exists in blood together with histones. In test tubes, histones can kill blood vessels and make blood thicker. However, no one has confirmed that DNA and/or histones are harmful to mammals and contributes to death in sepsis. Some new studies show that getting rid of DNA with injections of DNase I minimally increases survival in mice. Other studies show that removing histones with a treatment called heparin shows a small increase in survival in mice. Heparin is also a blood thinner and decreases inflammation. No one knows if these drugs used together can improve sepsis survival. Because both drugs on their own show some survival improvement in sepsis, perhaps using them together will cure sepsis. This thesis has three objectives: (1) to confirm the clotting properties of free-floating DNA, (2) to find out if DNA and/or histones contributes to death in sepsis, and (3) if using a combination of DNase I and heparin can cure sepsis in a mouse model. Finding new therapies for sepsis can save millions of people's lives and decrease the financial burden on society and healthcare systems.

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