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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.
51

Discovery of Novel Serum Biomarkers for Diagnosing and Staging Alzheimer's Disease

Shah, Dipti Jigar 01 June 2014 (has links) (PDF)
Discovery of Novel Serum Biomarkers for Diagnosing and Staging Alzheimer’s DiseaseDipti Jigar ShahDepartment of Chemistry and Biochemistry, BYUDoctor of PhilosophyAlzheimer’s disease (AD) is an untreatable neurologic disease affecting more than 5 million Americans, most over 60 years of age. Protein plaques and neurofibrillary tangles typify AD brain pathology and are thought to cause the progressive dementia and brain shrinkage observed in AD. Currently there are no methods to diagnose the disease at a time before damage becomes irreversible.Biochemical tests for AD using cerebrospinal fluid analysis or neuroimaging are not yet sufficiently sensitive and specific, and they are invasive. This points to a need for a more easily applied and more sensitive diagnostic test. Although the gross anatomical changes are localized to the brain, AD is likely to involve changes throughout the body. As a result of this, changes in the abundance of certain biomolecules present in the circulation system are likely to occur. Consequently, a serum proteomics approach able to measure such changes, when applied to AD, would likely find quantitative changes in relevant molecules that can help diagnose the disease correctly, ideally early in the disease process. The goal of this work was to discover and validate novel diagnostic serum biomarkers for AD. For biomarker discovery and validation, we used a novel serum proteomics approach involving reversed phase capillary-liquid chromatography-electrospray ionization-quadrupole-time of flight mass spectrometry. Our samples were protein depleted, which helped us survey low molecular weight species in the serum without ion suppression from larger proteins like albumin. We were able to observe more than 8000 molecular species in a single run. The overall project was comprised of four studies: (i) discovery of novel potential serum AD markers, (ii) blinded validation of diagnostically promising biomarkers found in the initial study, with their further chemical identification, (iii) exploring gender-based serum AD biomarkers, and (v) discovery of biomarkers that distinguish early versus moderate stage AD. In the first study, the approach found 38 significant (p < 0.05) biomarkers and 21 near significant (p = 0.05 to 0.099) biomarkers. On using the forward selection approach, we built multi-marker panels with specificities and sensitivities higher than 80%.The second study reports on a blinded validation study that was performed on a new set of serum samples. We focused on the 13 most promising AD biomarkers found as part of the initial study. We successfully validated 4 of these biomarkers that showed highly significant statistical p-values. As part of this study, research was conducted to identify these 4 biomarkers, which was accomplished using tandem mass spectrometry with fragmentation experiments. The third study used data from the initial study but looked at gender specific biomarkers. We found 31 significant and near significant serum AD biomarkers for women, 16 for men, and 25 that were gender independent. Multi-marker panels of AD biomarkers for women or men had sensitivities of >60% and specificities >85%.In the fourth study, cases with moderate AD were compared to cases with very mild or mild AD to find novel biomarkers that could be used for staging. We found 44 significant and near significant biomarkers that were quantitatively different between mild and severe AD. In conclusion, we were successful in accomplishing the goal of this work of finding, validating and identifying novel serum biomarkers that diagnose AD.
52

In Situ Reinforced Polymers Using Low Molecular Weight Compounds

Yordem, Onur Sinan 01 September 2011 (has links)
The primary objective of this research is to generate reinforcing domains in situ during the processing of polymers by using phase separation techniques. Low molecular weight compounds were mixed with polymers where the process viscosity is reduced at process temperatures and mechanical properties are improved once the material system is cooled or reacted. Thermally induced phase separation and thermotropic phase transformation of low molar mass compounds were used in isotactic polypropylene (iPP) and poly(ether ether ketone) (PEEK) resins. Reaction induced phase separation was utilized in thermosets to generate anisotropic reinforcements. A new strategy to increase fracture toughness of materials was introduced. Simultaneously, enhancement in stiffness and reduction in process viscosity were also attained. Materials with improved rheological and mechanical properties were prepared by using thermotropic phase transformations of metal soaps in polymers (calcium stearate/iPP). Morphology and thermal properties were studied using WAXS, DSC and SEM. Mechanical and rheological investigation showed significant reduction in process viscosity and substantial improvement in fracture toughness were attained. Effects of molecular architecture of metal soaps were investigated in PEEK (calcium stearate/PEEK and sodium stearate/PEEK). The selected compounds reduced the process viscosity due to the high temperature co-continuous morphology of metal soaps. Unlike the iPP system that incorporates spherical particles, interaction between PEEK and metal soaps resulted in two discrete and co-continuous phases of PEEK and the metal stearates. DMA and melt rheology exhibited that sodium stearate/PEEK composites are stiffer. Effective moduli of secondary metal stearate phase were calculated using different composite theories, which suggested bicontinuous morphology to the metal soaps in PEEK. Use of low molecular weight crystallizable solvents was investigated in reactive systems. Formation of anisotropic reinforcements was evaluated using dimethyl sulfone (DMS) as the crystallizable diluent and diglycidyl ether of bisphenol-A (DGEBA)/m-phenylene diamine (mPDA) material system as the epoxy thermoset. Miscible blends of DMS and DGEBA/mPDA form homogenous mixtures that undergo polymerization induced phase separation, once the DGEBA oligomers react with mPDA. The effect of the competition between the crystallization and phase separation of DMS resulted in nano-wires to micro-scale fiber-like crystals that were generated by adjusting the reaction temperature and DMS concentration.
53

Profiling of Low-Molecular-Weight Carbonyls and Protein Modifications in Flavored Milk

Wölk, Michele, Schröter, Theres, Hoffmann, Ralf, Milkovska-Stamenova, Sanja 13 April 2023 (has links)
Thermal treatments of dairy products favor oxidations, Maillard reactions, and the formation of sugar or lipid oxidation products. Additives including flavorings might enhance these reactions or even induce further reactions. Here we aimed to characterize protein modifications in four flavored milk drinks using samples along the production chain—raw milk, pasteurization, mixing with flavorings, heat treatment, and the commercial product. Therefore, milk samples were analyzed using a bottom up proteomics approach and a combination of data-independent (MSE) and data-dependent acquisition methods (DDA). Twenty-one small carbonylated lipids were identified by shotgun lipidomics triggering 13 protein modifications. Additionally, two Amadori products, 12 advanced glycation end products (AGEs), and 12 oxidation-related modifications were targeted at the protein level. The most common modifications were lactosylation, formylation, and carboxymethylation. The numbers and distribution of modification sites present in raw milk remained stable after pasteurization and mixing with flavorings, while the final heat treatment significantly increased lactosylation and hexosylation in qualitative and quantitative terms. The processing steps did not significantly affect the numbers of AGE-modified, oxidized/carbonylated, and lipid-carbonylated sites in proteins.
54

Subcutaneous Injection Techniques of Anticoagulant Therapies

Morissette, Leah 01 May 2015 (has links)
Subcutaneous anticoagulant medications like Heparin and Low-Molecular Weight Heparin are injections that readily cause bruising, pain, induration, and hematoma formation at the injection site. It is known that these adverse reactions can be correlated to the technique used to administer these medications; however, there is no established technique that reduces bruising, pain, induration, and hematoma formation at the site. Currently, the only protocol for subcutaneous Heparin and Low-Molecular Weight Heparin is that it is to be administered subcutaneously in the abdomen and when using a prefilled syringe, the air bubble should not be removed. The purpose of this study was to identify current nursing practice for the administration of these medications and to compare the results to researched techniques that resulted in less adverse site reactions. A total of 33 participants were recruited. The survey targeted six researched techniques found, after a comprehensive literature review, to have reduced site adverse effects associated with subcutaneous Heparin and Low-Molecular Weight Heparin. After completing the survey, it was found that current practice does not reflect techniques researched to reduce bruising, pain, induration, and hematoma formation at the site. In fact, very few completed one of the six research techniques that were questioned, which included: a two minute application of a cold compress/pack before and/or after the injection, an injection duration lasting 30 seconds, slow removal of the needle over five seconds, application of pressure after the injection for a minimum of 30 seconds, use of a hot pack/compress after the injection, and the use of a3 mL syringe. It was also found that there were inconsistencies in techniques that have been previously established as current protocol for these medications.
55

Přenos nabitých a nenabitých částic přes modelové biologické membrány / Transport of charged and neutral particles across the model biomembranes

Parisová, Martina January 2012 (has links)
This work was focused on the preparation of model stabilized phospholipid membranes formed on porous polycarbonate carrier. 1,2-dipalmitoyl-sn-glycero-3-phosphocholin was used for their formation in hydrophilic pores of polycarbonate carrier. For characterization of the formation of phospholipid layers, their changes and a study of transport processes, electrochemical impedance spectroscopy and voltammetry were used. Transport of cadmium and copper ions was studied in the presence and in the absence of ionophore calcimycin which was incorporated into the formed of phospholipid membrane. Because these ions are often bound in complexes with various substances, such as low molecular weight organic acids (LMWOAs), this work was also focused on the transport of copper and cadmium ions across the model phospholipid membranes in the presence of malic acid, citric acid and oxalic acid at different pH. Besides the use of ionophore, some pilot experiments were performed to realize the transfer of copper ions using two peptides, nisin and transportan 10. Formation of phospholipid membranes and the transport processes were characterized by two proposed electric equivalent circuits which correspond to the covered and to the uncovered polycarbobate carrier. Keywords: Phospholipids, Membranes, Ionophore, Peptid....
56

Perfil da proteína tirosina fosfatase de baixo peso molecular em células osteoblásticas / Partial biochemistry characterization and obtention of low molecular weight acid phosphatase from osteoblasts cultures

Muniz, Fernanda Magalhães Correa 01 September 2008 (has links)
Eventos como fosforilação e desfosforilação estão presentes nos processos de crescimento e diferenciação celular. As proteínas tirosina fosfatases estão envolvidas nestes processos. Estas enzimas são encontradas em animais, plantas e ocorrem em diversas formas, diferindo no peso molecular, substrato específico e sensibilidade a inibidores. As enzimas que possuem baixo peso molecular (entre 18-20 KDa), hidrolisam p-nitrofenilfosfato e são sensíveis ao p-hidroximercuribenzoato são chamadas como proteínas tirosina fosfatases de baixo peso molecular relativo (PTP-BMr) ou fosfatases ácidas. Vários dados sugerem que tipos de células de osso, como osteoblastos, podem expressar esta enzima ativa. Aqui, culturas de osteoblastos derivadas da medula removida do fêmur de rato foram investigadas para padronizar a metodologia de obtenção da PTP-BMr. A expressão e atividade catalítica desta enzima em diferentes estágios de crescimento de osteoblastos também foram verificadas. Foi observado que são necessários de 16-19 dias de cultura para obter maiores níveis de atividade da PTP-BMr em extrato citoplasmático. O nível de expressão do gene da PTP-BMr foi determinado por PCR em tempo real e uma maior quantificação de RNAm foi obtida em 16 dias de crescimento de osteoblasto. A caracterização bioquímica parcial confirma uma banda de atividade em gel de poliacrilamida com peso molecular de 17,6 KDa, e pH ótimo de 5,5. A hidrólise do p-nitrofenilfosfato demonstra uma pequena cooperatividade relativa (n=1,2) com K0,5= 0,12 e Vmax= 3,5U/mg. Esta atividade foi fortemente inibida (60 a 75%) por molibdato de amônio (10mM); fosfato de sódio (10mM); ortovanadato de sódio (10mM) e p-hidroximercuribenzoato de sódio (10mM). Estas propriedades são típicas desta classe. A interação entre osteoblastos e diferentes superfícies pode ativar ou desativar genes. Este presente projeto investigou se a interação com superfície de titânio pode modificar o perfil de atividade da PTP-BMr. Quando em presença de uma superfície de titânio há um maior aumento na atividade catalítica do que nos níveis de RNAm da PTP-BMr o que sugere uma estimulação da enzima a qual pode estar auxiliando no processo de formação óssea. / Events as phosphorilation and desphosphorilation are experienced in cell growth and differentiation processes. Tyrosine phosphatases proteins are involved in these processes. These enzymes are found in animals, plants and occur in multiple forms, differing in relative molecular weight, substrate specificity and sensitivity to inhibitors. The enzymes that have low molecular weight (between 18-20KDa), hydrolize p-nitrophenilphosphate and are sensible to p-hidroximercuribenzoate are known as low molecular weight relative tyrosine phosphatase proteins (PTP-LMWr) or acid phosphatase. Several data suggest that bone cell types, such as osteoblasts, may express this enzyme activity. Here, osteosblast cultures derived from medulla removed from rat femur were investigated to standardize the methodology of PTP-LMW obtainment. The expression and the catalytic activity of this protein in different stages of osteoblast growth were checked as well. It was observed that 16-19 culture days are necessary to obtain greater levels of activity of PTP-LMW in the cytoplasmatic extracts. The gene expression level of PTP-LMW was determined by quantitative real-time PCR, and a greater quantity of mRNA was observed within sixteen days of osteoblast growth. The partial biochemistry characterization confirms a single active band in poliacrilamide gel with molecular weight of about 17.6KDa, and a pH-optimum around 5.5. p-nitrophenilphosphate hydrolysis shows a small cooperative behavior (n=1.2) with K0.5=0.12mM and Vmax=3.5U/mg. This activity was strongly inhibited (about 60-95%) by ammonium molybdate (10mM); sodium phosphate (10mM); sodium orthovanadate (10mM) and sodium p-hydroximercuribenzoate (10mM). These properties are typical for this enzyme class.
57

Hyperkoagulační stavy v graviditě a jejich komplikace

KABELOVÁ, Kristýna January 2019 (has links)
Hypercoagulable states occur when the process of hemostasis is disturbed. It manifests as a deep vein thrombosis or a pulmonary embolism. It is also one of the most common cardiovascular diseases. There are two factors- genetic and acquired. Inherent factors involve coagulation inhibitor deficiency, prothrombin gene mutation and activated protein C resistance. Acquired factors include antiphospolipid syndrome, pregnancy, overweight etc. The analytic part of the thesis is focused on the effect of a low molecular weight heparin. It was shown in many theses that the LMWH could have a negative impact on a parturition complications or a week of parturition, a birth weight. The results of statistical analysis show that there is a coherence between the week of parturition and the type of parturition. What is more, the anticoagulation drug therapy shows a positive effect on the week of parturion. The data used in the thesis originate in laboratory information management system of Clinical Haematology ward in the hospital Nemocnice České Budějovice a.s.
58

Caracterização do processo de descoloração de corante reativo diazo por basidiomicetos tropicais. / Characterization of reactive disazo dye decolorization by tropical basidiomycetes.

Nara Ballaminut 01 February 2017 (has links)
Corantes reativos têxteis podem ser degradados por basidiomicetos, por meio de enzimas oxidativas e hidrolíticas, e compostos de baixa massa molar. Foi avaliada a descoloração de CI Reactive Blue 222 por Peniophora cinerea, Pleurotus ostreatus e Trametes villosa, selecionando condições ótimas para o processo e diferentes vias metabólicas foram observadas. A degradação foi confirmada por cromatografia de camada delgada. Foi sugerido que lacases de P. ostreatus oxidam o grupo cromóforo azo, ligado ao fenol, nas primeiras 24 horas, conjuntamente hidroxilização não enzimática. Lacases de P. cinerea oxidam Mn+2 e quinona, possibilitando a via de Fenton e hidroxilizando assim a molécula do corante, paulatinamente, a partir das ligações mais vulneráveis. T. villosa faz uso prioritariamente da via de Fenton, hidroxilizando gradativamente a molécula do corante. Dessa forma, embora a maioria de estudos associem a produção enzimática à descoloração, a participação dos compostos de baixa massa molar não pode ser negligenciada. / Reactive textile dyes can be degraded by basidiomycetes, by means of hydrolytic and oxidative enzymes, and low molecular weight compounds. Was evaluated the CI Reactive Blue 222 decolorization by Peniophora cinerea, Pleurotus ostreatus, and Trametes villosa, selecting optimal conditions for the process and different metabolic pathways were observed. The degradation was confirmed by thin layer chromatography. It was suggested that P. ostreatus laccases oxidize azo chromophore group attached to the phenol, within 24 hours, together nonenzymatic hydroxylizating. P. cinerea laccases oxidize Mn+2 and quinone, enabling via Fenton and so hidroxylizing the dye molecule, gradually, from the most vulnerable links. T. villosa uses primarily via Fenton, gradually hidroxylizing the dye molecule. Thus, although most studies have linked enzyme production with the decolorization, the share of low molecular weight compounds can not be neglected.
59

Antibody and Antigen in Heparin-Induced Thrombocytopenia

Newman, Peter Michael, Pathology, UNSW January 2000 (has links)
Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.
60

Novel Analytical Techniques For the Assessment of Degradation of Silicone Elastomers in High Voltage Applications

Sovar, Robert D. January 2005 (has links)
Over the last 20 years "composite" insulators have been increasingly used in high voltage applications as an alternative traditional materials. More recently, polydimethylsiloxane (PDMS) have been used as weather sheds on these composite insulators. The main attraction with PDMS is that the surface hydrophobicity can be recovered following pollution or surface discharges. Among the possible mechanisms for recovery the most likely is the migration of low molecular weight silicone oil (LMWS) from the bulk to the surface encapsulating pollutant particles. Although it is widely recognised that the migration of LMWS is the cause of this recovery of hydrophobicity, the mechanism of what actually occurs is not well understood. It is also not known for how long this process will continue. The main objective of this study program was to gain improved understanding of the surface hydrophobic recovery process that is unique to polydimethlysiloxane high-voltage insulators. Fundamental knowledge of this mechanism has been increased through the development of the Contact Angle DRIFT Electrostatic Deposition (CADED) novel analytical technique. This technique enabled study of the degradation of silicone elastomers subjected to high voltage environments by closely following LMWS migration from the bulk material to the surface and linking it to the contact angle measurements. The migration rate data showed that the aged material recovered faster that the virgin material. Differences in the rate and maximum surface levels of silicone were seen between materials from different manufacturers. This has significant implications for the life-time of these materials A model system has been developed to examine LMWS diffusion through the bulk material and into the interface of surface and pollutant. This was achieved by examining theoretical and empirically derived equations and using existing experimental data to better understand the mechanism of recovery. This diffusion was Fickian in the initial stages of recovery. X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to substantiate the degree of degradation in in-field silicone insulators by quantifying the levels of the major degradation products: silica and silica-like material and alumina.

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