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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.
31

Novel NAD+ metabolomic technologies and their applications to Nicotinamide Riboside interventions

Trammell, Samuel A.J. 01 May 2016 (has links)
Nicotinamide adenine dinucleotide (NAD+) is a cofactor in hydride transfer reactions and consumed substrate of several classes of glycohydrolyitc enzymes, including sirtuins. NAD+, its biosynthetic intermediates, breakdown products, and related nucleotides (the NAD metabolome) is altered in many metabolic disorders, such as aging and obesity. Supplementation with the novel NAD+ precursor, nicotinamide riboside (NR), ameliorates these alterations and opposes systemic metabolic dysfunctions in rodent models. Based on the hypothesis that perturbations of the NAD metabolome are both a symptom and cause of metabolic disease, accurate assessment of the abundance of these metabolites is expected to provide insight into the biology of diseases and the mechanism of action of NR in promoting metabolic health. Current quantitative methods, such as HPLC, lack specificity and sensitivity to detect distinct alterations to the NAD metabolome. In this thesis, I developed novel sensitive, accurate, robust liquid chromatography mass spectrometry methodologies to quantify the NAD metabolome and applied these methods to determine the effects of disease states and NR supplementation on NAD+ metabolism. My investigations indicate that NR robustly increases the NAD metabolome, especially NAD+ in a manner kinetically different than any other NAD+ precursor. I provide the first evidence of effective NAD+ supplementation from NR in a healthy, 52 year old human male, suggesting the metabolic promoting qualities of NR uncovered in rodent studies are translatable to humans. During my investigation of NR supplementation, my work establishes an unexpected robust, dramatic increase in deamino–NAD+, NAAD, directly from NR, which I argue could serve as an accessible biomarker for efficacious NAD+ supplementation and the effect of disease upon the NAD metabolome. Lastly, I further establish NR as a general therapeutic against metabolic disorder by detailing its ability to oppose aspects of chronic alcoholism and diabetes mellitus.
32

CHARACTERIZATION OF VASCULAR CALCIFICATION IN A RODENT MODEL OF CHRONIC KIDNEY DISEASE

SEYED SHOBEIRI, NAVID 17 December 2009 (has links)
Chronic kidney disease (CKD) is a worldwide health problem with rising incidence and high cardiovascular mortality. CKD compromises cardiovascular function, in part, characterized by vascular calcification (VC), elevated pulse wave velocity (PWV) and pulse pressure (PP). Through manipulation of dietary adenine, we produced a model characterized by graded severity of CKD, VC and hyperphosphatemia. To our knowledge, we are the first to explore the relationship between aortic calcium content and changes in circulatory function in rodents with CKD. Fourteen-week old Sprague-Dawley rats received a diet containing an adenine concentration (0.25-0.75%) plus high-normal dietary phosphate (1%), for up to 10 weeks. Circulatory changes were determined by arterial radiotelemetry (n=6) and by assessment of aortic pulse wave velocity (PWV, n=32). VC was assessed using the calcium-O-cresophthalein-complexone assay. At sacrifice, kidney function (creatinine (µmol/L)) was worst in the group with VC (251.3±60.2 µmol/L), compared to non-calcifying CKD (200.3±68.8 µmol/L) or control (50.0±16.2 µmol/L). PWV (cm/s) adjusted for blood pressure (BP) was markedly elevated in animals with VC (3.23±0.33 log(cm/s)) versus non-calcifying CKD (2.85± 0.12 log(cm/s)) or control (2.96±0.08 log(cm/s)). Arterial pressure radiotelemetry revealed that there was an increase in pulse pressure (38±4.7 mmHg to 58 ±15.2 mmHg) during the development of VC. Systolic pressure remained relatively stable throughout (129±8.7 mmHg), diastolic pressure fell during weeks 9 and 10 of the study (91±6.0 mmHg down to 74±9.1 mmHg), a fall that almost fully accounted for the changes in pulse pressure. The calcifying CKD animals also exhibited left ventricular hypertrophy (LVH) compared to CKD or control animals (2.32±0.3 vs 2.03±0.2, 1.80±0.1 g/kg respectively). Manipulating dietary adenine produces a graded severity of CKD with calcification which impact circulatory changes (PP and PWV). These altered circulatory functions are likely to be key factors in the enhanced LVH. This model appears to be a useful for the study of CKD-associated VC. / Thesis (Master, Pharmacology & Toxicology) -- Queen's University, 2009-12-16 15:10:49.384
33

Effects of ribose supplementation on adenine nucleotide metabolism in human skeletal muscle during high-intensity exercise

Gallagher, Philip M. January 2000 (has links)
During periods of intense exercise the adenine nucleotide pool in skeletal muscle becomes partially depleted. Ribose has been shown to increase rates of both purine salvage and adenine nucleotide de novo synthesis in rat skeletal muscle. However, to date no research has been conducted on the effects of ribose on adenine nucleotide levels in human skeletal muscle. Therefore, the purpose of this investigation was to determine the effects of ribose supplementation on adenine nucleotide levels in human skeletal muscle during high-intensity exercise. To do this, an 11-day supplementation of either ribose (20 g.d-1) or placebo (glucose 20 g•d-1) was given to 16 healthy male subjects. After 72 hours of supplementation, the subjects performed five-days of high-intensity exercise designed to elicit significant reductions in adenine nucleotides. A 65 hour recovery period was completed following the exercise protocol. Muscle biopsies were performed at four different time points during the supplementation/exercise period.The exercise protocol elicited significant decreases in skeletal muscle adenine nucleotide levels of both the ribose and placebo groups (p<0.05). However, ribose supplementation was shown to partially attenuated the adenine nucleotide decrease. The placebo group demonstrated a 39% decrease, while the ribose group dropped 23% in TAN levels (p<0.05). The largest decreases were observed in ATP for both groups; however, the decreases were significantly greater in the placebo group (p<0.05). Both groups displayed a similar amount of replenishment in adenine nucleotides 65 hours following the 5-day exercise period. No differences were demonstrated in ADP or AMP for either the ribose and placebo groups throughout the investigation. Both groups displayed an increase in E MP post-exercise, but the increase was only significant in the ribose group (p<0.05). No differences in mean power, peak power, and fatigue were observed between the ribose and placebo group. However, the ribose group consistently displayed a non-significantly greater percent change (3.1 %) in mean power. / School of Physical Education
34

Etablierung zellbasierter Hypoxiemodelle und Untersuchungen zur Wirkung potentiell protektiver Pharmaka

Siegert, Fritzi 12 April 2011 (has links) (PDF)
Der Hirninfarkt ist einer der drei häufigsten Todesursachen in Deutschland. Er wird durch eine Unterversorgung des Gewebes mit Sauerstoff und Nährstoffen, häufig infolge von Gefäßverschlüssen, ausgelöst. Die bisher einzige Therapiemöglichkeit ist die Thrombolyse. Deshalb sind neue Therapieansätze nötig. Voraussetzung dafür sind geeignete Modelle. In dieser Arbeit wurden zellbasierte Hypoxiemodelle etabliert und charakterisiert. Es wurde der Einfluss von Sauerstoff- und/oder Glucoseentzug an humanen primären Makrophagen untersucht. Für Screeninguntersuchungen wurden neuronale und periphere (Makrophagen) Zelllinien von Ratte und Mensch verwendet. Im zweiten Teil der Arbeit wurden die Modelle genutzt, um die Wirkung von Adenin, eine rezeptorvermittelte Therapieoption, und des Phytopharmakons STW5 auf mögliche protektive Wirkungen zu untersuchen. Es wurden zellbiologische (MTT-Test, LDH-Test, DAPI-Färbung), immunologische (TNF α- ELISA, immunhistochemische Färbung), elektrophysiologische (Patch Clamp-Technik) und molekularbiologische (RT-PCR, Real-Time-PCR) Methoden angewendet. Es wurde erstmals der Adeninrezeptor an den untersuchten Zelllinien nachgewiesen und der pharmakologische Hinweis für eine bisher unbekannte humane Variante des Rezeptors erbracht. An neuronalen Zellen kam es zu einer Rezeptorinteraktion zwischen Adenin- und Adenosin-A1-Rezeptor. Antagonisten am Adeninrezeptor scheinen zur Behandlung hypoxiebedingter Zellschäden geeignet zu sein. STW5 hemmte unter hypoxischen Bedingungen die TNF α-Freisetzung humaner primärer Makrophagen. Der antiinflammatorischen Wirkung liegt die Blockierung erhöhter Kaliumströme zugrunde. An den untersuchten Zelllinien wirkte STW5 der hypoxieinduzierten Zellschädigung entgegen.
35

Functional Annotation and Mechanistic Characterization of Enzymes with Unknown Functions: Studies on Adenine Deaminase, N-6-Methyladenine Deaminase and the C-P Lyase Pathway

Kamat, Siddhesh 2012 August 1900 (has links)
Adenine deaminase (ADE) catalyzes the conversion of adenine to hypoxanthine. Mechanistic characterization of ADE from Escherichia coli was performed along with biophysical studies. The structure of ADE was solved from A. tumefaciens. The structure, along with the biochemical and biophysical characterization, enabled the elucidation of the mechanism of the deaminase reaction of ADE. Elucidation of the origin of the oxygenation reactions within ADE led to the discovery of a promiscuous catalase reaction. The diiron ADE from all tested bacterial species exhibited this unusual reaction, along with the generation of superoxide and hydroxyl radicals, the latter being responsible for the oxygenation of the protein. The residues that were identified to be oxygenated were primarily the metal binding residues implying the origin of this reaction was the binuclear iron center. A group of bacterial enzymes that are co-localized in the same genomic operon as ADE but of unknown function were identified. The enzyme Bh0637 from Bacillus halodurans, a representative member of this group of enzymes was characterized. This enzyme was shown to preferentially catalyze the deamination of epigenetic base, N-6-methyadenine. Lastly, gram-negative bacteria have a highly conserved phn operon composed of 14 genes to break the C-P bond of inert alkylphosphonates. The genes phnGHIJKLM are absolutely critical for this activity. We discovered that methylphosphonate reacts first with MgATP to form alpha-D-ribose-1-methylphosphonate-5-triphosphate (RPnTP) and adenine by the action of PhnI, PhnG, PhnH and PhnL. PhnI by itself was shown to perform a novel nucleosidase reaction converting MgATP to ribose-5-triphosphate and adenine. The triphosphate moiety of RPnTP is then hydrolyzed to pyrophosphate and alpha-D-ribose-1-methylphosphonate-5-phosphate (PRPn) by PhnM. The carbon-phosphorus bond of PRPn is subsequently cleaved via a radical-based reaction to alpha-D-ribose-1,2-cyclic-phosphate-5-phosphate (PRcP) and methane in the presence of S-adenosyl-L-methionine by PhnJ.
36

The polyadenylation of mRNA by hepatocytes isolated from Fischer F344 rats

Sparks, Maria Constanza. Richardson, Arlan. January 1981 (has links)
Thesis (Ph. D.)--Illinois State University, 1981. / Title from title page screen, viewed March 24, 2005. Dissertation Committee: Arlan Richardson (chair), Herman Brockman, Fritz Schwalm, Harry Huizinga, Tak Cheung. Includes bibliographical references (leaves 81-89) and abstract. Also available in print.
37

Primary and secondary transport in membrane vesicles from Bacillus subtilis

Bergsma, Jacob. January 1983 (has links)
Thesis (doctoral)--Rijksuniversiteit te Groningen. / Description based on print version record.
38

Kinetic analysis of the contribution of base flipping to the substrate specificity and catalytic activity of human alkyladenine dna glycosylase

Vallur, Aarthy C., January 2004 (has links)
Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 135 pages. Includes Vita. Includes bibliographical references.
39

Síntese, caracterização e avaliação do potencial em drug delivery de BioMOFs (Biocompatible Metal-Organic Frameworks) de Zn (II) / Synthesis, characterization and evaluation of the potential for drug delivery of BioMOFs (Biocompatible Metal-Organic Frameworks) of Zn (II)

Lucena, Guilherme Nunes [UNESP] 29 July 2016 (has links)
Submitted by GUILHERME NUNES LUCENA null (guilherme_nunes7@hotmail.com) on 2016-08-17T13:42:12Z No. of bitstreams: 1 Dissertacao Final-CD.pdf: 3721142 bytes, checksum: e52f98f99b251e2672bb3539739035b1 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-08-18T14:13:36Z (GMT) No. of bitstreams: 1 lucena_gn_me_araiq.pdf: 3721142 bytes, checksum: e52f98f99b251e2672bb3539739035b1 (MD5) / Made available in DSpace on 2016-08-18T14:13:36Z (GMT). No. of bitstreams: 1 lucena_gn_me_araiq.pdf: 3721142 bytes, checksum: e52f98f99b251e2672bb3539739035b1 (MD5) Previous issue date: 2016-07-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Metal-Organic Frameworks (MOFs) são polímeros ou redes de coordenação que possuem estrutura aberta contendo poros potencialmente disponíveis. Por serem cristalinos, porosos, leves e possuírem valores elevados de área específica e considerável estabilidade térmica, essa nova classe de compostos vem sendo estudada em diversas áreas como armazenamento e separação de gases, catálise heterogênea, drug delivery, sensores químicos, entre outras. A possibilidade de construção desses materiais porosos usando bioelementos e ligantes orgânicos biocompatíveis ou com atividade biológica deu origem aos BioMOFs (Biocompatible Metal-Organic Frameworks). Esses compostos, além das características já descritas anteriormente, possuem baixa ou nenhuma citotoxicidade frente a células humanas, sendo adequados então para serem investigadas em drug delivery. Desta forma, objetiva-se neste trabalho realizar a síntese, caracterização e avaliação do potencial em drug delivery de BioMOFs baseados no ligante adenina e íons zinco (II). Na primeira etapa do trabalho foi investigado o efeito de alterações nas condições de síntese de um sistema já estudado na literatura (BioMOF-1 e BioMOF-100), incluindo pH e razão CTAB:Zn. Medidas de difração de raios-X do pó e ressonância magnética nuclear no estado sólido mostraram que, de uma maneira geral, as mudanças nesses parâmetros levaram à formação de um mesmo produto, o BioMOF-1. No entanto, medidas de fisissorção de N2 e fotoluminescência evidenciaram um material com porosidade e luminescência, respectivamente, distintas das observadas em seus análogos. Incrementos no pH da síntese diminuíram nucleação dos cristais do BioMOF-Zn levando a obtenção de cristais de até 31,11 µm em pH 6,75. A presença do surfactante CTAB também influenciou a nucleação dos cristais de BioMOF-Zn, sendo possível obter partículas de até 46,73 µm com o uso da razão CTAB:Zn igual a 1. Experimentos de fisissorção de N2 revelaram a natureza micro e mesoporosa do BioMOF-Zn, com diâmetros de porode 5,70 nm e área específica de 350,71 m2 g-1. Esse composto também apresenta forte emissão no visível em 465 nm quando excitado com radiação UV (λex = 365 nm). Ensaios de drug delivery mostraram que o BioMOF-Zn tem alta capacidade de adsorção de diclofenaco de sódio (1,78 g do fármaco por grama de material em 7 dias de encapsulamento). Aliado a isto, o perfil de liberação do diclofenaco em tampão PBS pH 7,4 (56% após 48 horas) revela que este material pode ser considerado um promissor candidato a carregador de fármacos aniônicos em sistemas de drug delivery. / Metal-Organic Frameworks (MOFs) are coordination polymers that have an open structure, containing potentially void porous. Being crystalline, porous, light and have high values of specific area and a considerable thermal stability, this new class of compounds has been studied in various fields such as storage and separation gas, heterogeneous catalysis, drug delivery, chemical sensors, among others. The possibility of construction of porous materials using bioelements and biocompatible organic ligands with biological activity provided the called BioMOFs (Biocompatible Metal-Organic Frameworks). Moreover, these class of materials has a low or none citotoxicity against human cells, being suitable to be investigated in drug delivery systems. Thus aim of this study is synthesis, characterization and evaluation potential of drug delivery of BioMOFs based on adenine linker and zinc (II). In the first stage of the work was investigated the effect of changes in conditions of synthesis of a system have reported, the BioMOF-1 and BioMOF-100, including pH and CTAB:Zn ratio. Powder x-ray diffraction and nuclear magnetic resonance measurements showed that in general, changes in these parameters led to the formation of a single product, the BioMOF-1.However, nitrogen adsorption and photoluminescence measurements showed a material with porosity and luminescence, respectively, different of the analogues it. Increase in pH of the synthesis decreased nucleation of BioMOF-Zn crystals, leading to obtaining crystals of up 31,11 µm at pH 6,75. The presence of CTAB surfactant also influenced BioMOF-Zn crystals nucleation, it is possible to obtain particles of up to 46,73 µm using the CTAB:Zn ratio equal to 1. Nitrogen adsorption studies showed a micro and mesoporous nature of BioMOF-Zn, with average pore size of 5.70 nm and BET surface area of 350 m2 g -1. These material also shows stronger emission in visible at 465 nm upon excited with UV ligth (λex = 365 nm). Drug delivery experiments showed that BioMOF-Zn has a high capacity for adsorption of diclofenac (1,78 drug per gram of material). Allied to this, the release profile of diclofenac in PBS buffer pH 7,4 (56% after 48 hours)reveals that this material it is a promising candidate for anionic molecules carrier in drug delivery systems. / CNPq: 830856/1999-4
40

Síntese, caracterização e avaliação do potencial em drug delivery de BioMOFs (Biocompatible Metal-Organic Frameworks) de Zn (II) /

Lucena, Guilherme Nunes. January 2016 (has links)
Orientador: Regina Célia Galvão Frem / Banca: Leandro Martins / Banca: Roberto Santana da Silva / Resumo: Metal-Organic Frameworks (MOFs) são polímeros ou redes de coordenação que possuem estrutura aberta contendo poros potencialmente disponíveis. Por serem cristalinos, porosos, leves e possuírem valores elevados de área específica e considerável estabilidade térmica, essa nova classe de compostos vem sendo estudada em diversas áreas como armazenamento e separação de gases, catálise heterogênea, drug delivery, sensores químicos, entre outras. A possibilidade de construção desses materiais porosos usando bioelementos e ligantes orgânicos biocompatíveis ou com atividade biológica deu origem aos BioMOFs (Biocompatible Metal-Organic Frameworks). Esses compostos, além das características já descritas anteriormente, possuem baixa ou nenhuma citotoxicidade frente a células humanas, sendo adequados então para serem investigadas em drug delivery. Desta forma, objetiva-se neste trabalho realizar a síntese, caracterização e avaliação do potencial em drug delivery de BioMOFs baseados no ligante adenina e íons zinco (II). Na primeira etapa do trabalho foi investigado o efeito de alterações nas condições de síntese de um sistema já estudado na literatura (BioMOF-1 e BioMOF-100), incluindo pH e razão CTAB:Zn. Medidas de difração de raios-X do pó e ressonância magnética nuclear no estado sólido mostraram que, de uma maneira geral, as mudanças nesses parâmetros levaram à formação de um mesmo produto, o BioMOF-1. No entanto, medidas de fisissorção de N2 e fotoluminescência evidenciaram um material... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Metal-Organic Frameworks (MOFs) are coordination polymers that have an open structure, containing potentially void porous. Being crystalline, porous, light and have high values of specific area and a considerable thermal stability, this new class of compounds has been studied in various fields such as storage and separation gas, heterogeneous catalysis, drug delivery, chemical sensors, among others. The possibility of construction of porous materials using bioelements and biocompatible organic ligands with biological activity provided the called BioMOFs (Biocompatible Metal-Organic Frameworks). Moreover, these class of materials has a low or none citotoxicity against human cells, being suitable to be investigated in drug delivery systems. Thus aim of this study is synthesis, characterization and evaluation potential of drug delivery of BioMOFs based on adenine linker and zinc (II). In the first stage of the work was investigated the effect of changes in conditions of synthesis of a system have reported, the BioMOF-1 and BioMOF-100, including pH and CTAB:Zn ratio. Powder x-ray diffraction and nuclear magnetic resonance measurements showed that in general, changes in these parameters led to the formation of a single product, the BioMOF-1.However, nitrogen adsorption and photoluminescence measurements showed a material with porosity and luminescence, respectively, different of the analogues it. Increase in pH of the synthesis decreased nucleation of BioMOF-Zn crystals, leading t... (Complete abstract click electronic access below) / Mestre

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