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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.
11

The Antioxidant Defense Network: Synergistic Combinations to Prevent Oxidative Damage

Clement, Amy Marie 13 August 2008 (has links) (PDF)
One of the matchless ironies of the human body is its requirement for the highly reactive oxygen molecule, which has been clearly implicated in many diseases and the aging processes. Oxidants produced by metabolic processes damage cells by starting chemical chain reactions including oxidation of DNA and proteins as well as lipid peroxidation. Damage to DNA can cause mutations and lead to cancer if not reversed by DNA repair mechanisms. Damage to proteins causes enzyme inhibition, denaturation and protein degradation. Lipid peroxidation can cause cell lysis as well as creating mutagenic and carcinogenic by-products. The human body contains antioxidants and enzymes that together work to prevent oxidative damage to cellular components. By and large antioxidants either prevent these reactive oxygen species from being formed or remove them before they cause damage. There are many theories currently that tout the superior nature of diverse antioxidant combinations. One such theory is by Dr. Lester Packer of The University of California at Berkley. Dr. Packer puts forth the hypothesis that there is a superlative combination of five antioxidants that have the ability to "recharge" one another both in the blood plasma and intracellularly. This would result in a greater quality of antioxidant protection for an extended time. The current study evaluates Dr. Packer's theory of antioxidant combination from his book The Antioxidant Miracle. The decay rate of the antioxidants vitamin E, vitamin C, lipoic acid, glutathione, and coenzyme Q10 alone and in combination were determined using the ORAC (Oxygen Radical Absorbance Capacity) assay. The majority of the antioxidants retained activity for longer periods of time when tested alone, rather than in combination as Dr. Packer's theory would suggest. The assay was also preformed (using the same antioxidants and combinations) on oxidatively damaged Raji cancer cells. Cell viability and uptake of antioxidants into the cytoplasm were monitored. Finally, a variety of multivitamins were subjected to the ORAC assay and their antioxidant capacity compared to that of the "Packer Combination". The results suggest that multivitamins are superior antioxidants than the Packer ratio listed in The Antioxidant Miracle.
12

Avaliação da função mitocondrial muscular e sua repercussão na capacidade funcional nos pacientes com distrofia muscular de Duchenne / Assessment of mitochondrial function in muscle and its relation to functional capacity in patients with Duchenne muscular dystrophy

Okama, Larissa de Oliveira 10 August 2018 (has links)
A distrofia muscular de Duchenne (DMD) é uma doença hereditária, degenerativa e progressiva dos músculos esqueléticos. É causada pela ausência da proteína distrofina e caracterizada pela perda progressiva da força muscular e deterioração da capacidade funcional. Alterações na regulação da homeostase do cálcio, proteólise e alterações metabólicas, especialmente mitocondriais, são parte da patogênese da doença. A coenzima Q (CoQ10), potente antioxidante que participa da atividade da cadeia respiratória, tem sido utilizada em ensaios clínicos, entretanto, não há estudos que evidencie seu comprometimento na DMD. O objetivo deste estudo foi avaliar a CoQ10 e a da atividade da cadeia respiratória em fragmentos de biópsia muscular de pacientes com DMD e sua correlação com parâmetros clínicos e a capacidade funcional. O estudo constitui de uma etapa retrospectiva, onde foram analisadas 22 biópsias musculares de pacientes com DMD, e outra prospectiva, onde foram avaliados dez pacientes com DMD. Dez pacientes controles foram utilizados nas duas etapas do estudo. A concentração da CoQ10 foi realizada através da técnica de cromatografia líquida de alta performance de fase reversa. As atividades das enzimas da cadeia respiratória foram medidas através de técnicas espectrofotométricas. A capacidade funcional foi mensurada através das escalas Medida da Função Motora (MFM) e Escala de Avaliação para deambulantes North Star (NSAA), e dos testes cronometrados: tempo para percorrer 10 metros (T10), tempo para realizar a manobra de Gowers (TGowers) e teste da caminhada dos 6 minutos (TC6min). Fase retrospectiva: a média de idade dos pacientes com DMD foi de 6,9 anos, (DP ±2,4) e controles de 8 anos, (DP ±2,69). A dosagem média de CoQ10 nos fragmentos de pacientes com DMD foi de 8,6 µg/g de tecido (DP ±3,9) e nos fragmentos dos controles foi de 31,6 µg/g de tecido (DP ±6,9). A média da área ocupada por fibras musculares nos pacientes com DMD foi de 27,3% (DP ±14,2%) e nos controles foi de 89,2% (DP ±3,3%). Evidenciou-se alta correlação entre aquantidade de CoQ10 e a área relativa ocupada por fibras musculares (r= 0,767 e p= 0,016). As atividades dos complexos enzimáticos da cadeia respiratória dos pacientes com DMD não demonstraram deficiência. Já o resultado do ensaio conjunto dos complexos II+III, encontra-se significativamente reduzido nos pacientes com DMD. Etapa prospectiva: a média de idade dos pacientes com DMD foi de 6,5 anos, (DP ±2,4). A dosagem média de CoQ10 nos fragmentos de pacientes com DMD foi de 12,6 µg/g de tecido (DP ±5,1). A média da área ocupada por fibras musculares nos pacientes com DMD foi de 40,3% (DP ±20,4%). Houve alta correlação entre a quantidade de CoQ10 e a área relativa ocupada por fibras musculares (r= 0,690 e p= 0,058). A correlação da dosagem da CoQ10 com os instrumentos de avaliação da capacidade funcional foi alta com o TGowers e moderada com MFM total e dimensões 1 e 2, NSAA, T10 e TC6min. Em relação à área relativa de fibras musculares, houve moderada correlação com a dimensão 1 da MFM e com o TGowers. Não houve correlação da CoQ10 e da área relativa ocupada por fibras musculares com os parâmetros clínicos: idade no momento da biópsia, idade do início dos sintomas e tempo de evolução da doença. No presente estudo, concluímos que existe uma deficiência secundária de CoQ10 em pacientes com DMD, a qual contribui para entender a fisiopatologia da doença e com grande relevância para as propostas terapêuticas. / Duchenne muscular dystrophy (DMD) is a hereditary, degenerative and progressive skeletal muscles disease. It is caused by the absence of the protein dystrophin and characterized by progressive loss of muscle strength and deterioration of functional capacity. Alterations in the regulation of calcium homeostasis, proteolysis and metabolic abnormalities, especially mitochondrial dysfunction, are part of the pathogenesis of the disease. Coenzyme Q (CoQ10), a potent antioxidant that participates in respiratory chain activity, has been used in clinical trials, however, there are no studies showing its involvement in DMD. The purpose of this study was to investigate CoQ10 content and respiratory chain activity in muscle biopsy of patients with DMD and its correlation with clinical parameters and functional capacity. The study consisted of a retrospective phase, in which 22 muscle biopsies from patients with DMD were analyzed, and a prospective phase, where ten patients with DMD were evaluated. The same control group of ten patients were used in the two phases of the study. The concentration of CoQ10 was measured using the reverse phase high performance liquid chromatography technique. Activities of the respiratory chain enzymes were measured by spectrophotometry. The functional capacity was evaluated using the Motor Function Measurement (MFM) and North Star Ambulatory Assessment (NSAA) and the following timed tests: to run 10 meters (T10), to perform the Gowers maneuver (TGowers) and the 6-minute walk test (6MWT). Retrospective phase: the mean age of patients with DMD was 6.9 years (SD ± 2.4) and of controls was 8 years (SD ± 2.69). The mean CoQ10 content in fragments from patients with DMD was 8.6 ?g / g tissue (DP ± 3.9) and in fragments from controls was 31.6 ?g / g tissue (DP ± 6.9). The mean area occupied by muscle fibers in patients with DMD was 27.3% (SD ± 14.2%) and in controls was 89.2% (SD ± 3.3%). There was a high correlation between the amount of CoQ10 and the relative area occupied by muscle fibers (r= 0.767 and p= 0.016). The activities of respiratory chain enzymes from patients with DMD were not deficient. On the other hand, the results of the combined analysis of complexes II + III were significantly reduced in patients with DMD. Prospective phase: the mean age of patients with DMD was 6.5 years (SD ± 2.4). The mean CoQ10 content in fragments from patients with DMD was 12.6 ?g / g tissue (SD ± 5.1). The mean area occupied by muscle fibers in patients with DMD was 40.3% (SD ± 20.4%). There was a high correlation between the amount of CoQ10 and the relative area occupied by muscle fibers (r= 0.690 and p= 0.058). The correlation between the amount of CoQ10 and the functional capacity assessment instruments was high forTGowers and moderate for MFM total and dimensions 1 and 2, NSAA, T10 andd TC6min. Regarding the relative area of muscle fibers, there was a moderate correlation with MFM dimension 1 (standing position and transfers) and TGowers. There was no correlation between CoQ10 and relative area occupied by muscle fibers with clinical parameters: age at time of biopsy, age of onset of symptoms and time of disease progression. In the present study, we conclude that there is a secondary deficiency of CoQ10 in patients with DMD, which contributes for the understanding of its physiopathology and is relevant for therapy.
13

The Role of Mitochondrial Uncoupling in the Development of Diabetic Nephropathy

Friederich Persson, Malou January 2012 (has links)
Diabetes is closely associated with increased oxidative stress, especially originating from the mitochondria. A mechanism to reduce increased mitochondria superoxide production is to reduce the mitochondria membrane potential by releasing protons across the mitochondria membrane. This phenomenon is referred to as mitochondria uncoupling since oxygen is consumed independently of ATP being produced and can be mediated by Uncoupling Proteins (UCPs). However, increased oxygen consumption is potentially detrimental for the kidney since it can cause tissue hypoxia. Therefore, this thesis aimed to investigate the role of mitochondria uncoupling for development of diabetic nephropathy.      UCP-2 was demonstrated to be the only isoform expressed in the kidney, and localized to tubular segments performing the majority of tubular electrolyte transport. Streptozotocin-induced diabetes in rats increased UCP-2 protein expression and correlated to increased non-transport dependent oxygen consumption in isolated proximal tubular cells. These effects were prevented by intense insulin treatment to the diabetic animals demonstrating a pivotal role of hyperglycemia. Importantly, elevated UCP-2 protein expression increased mitochondria uncoupling in mitochondria isolated from diabetic kidneys. Mitochondria uncoupling and altered morphology was also evident in kidneys from db/db-mice, a model of type-2 diabetes, together with proteinuria and glomerular hyperfiltration which are both clinical manifestations of diabetic nephropathy. Treatment with the antioxidant coenzyme Q10 prevented mitochondria uncoupling as well as morphological and functional alterations in these kidneys. Acute knockdown of UCP-2 paradoxically increased mitochondria uncoupling in a mechanism involving the adenosine nucleotide transporter. Increased uncoupling via adenosine nucleotide transporter decreased mitochondria membrane potential and kidney oxidative stress but did not affect glomerular filtration rate, renal blood flow, total kidney oxygen consumption or intrarenal tissue oxygen tension.      The role of increased mitochondria oxygen consumption was investigated by administering the chemical uncoupler dinitrophenol to healthy rats. Importantly, increased mitochondria oxygen consumption resulted in kidney tissue hypoxia, proteinuria and increased staining of the tubular injury marker vimentin, demonstrating a crucial role of increased oxygen consumption per se and the resulting kidney tissue hypoxia for the development of nephropathy.      Taken together, the data presented in this thesis establishes an important role of mitochondria uncoupling for the development of diabetic nephropathy.
14

Influence of Oxidative Stress on Muscle and Bone

Östman, Bengt January 2009 (has links)
Reactive oxygen species (ROS) induce oxidative stress and although are primarily recognized for playing a deleterious biological role, they can be beneficial to cell systems. ROS are extremely short-lived and normally tightly regulated by antioxidant defence systems. Cells react to oxidative stress in different ways, which primarily depends on cell type, stress severity, or both. There is a general limitation in extrapolating to humans conclusions drawn from in vitro and animal studies because of important species-specific differences. Therefore, the general aim of this thesis was to study the influence of oxidative stress on human muscle and bone in vivo. In paper I we presented a one-step HPLC method optimized for the simultaneous determination of purine degradation products in small microdialysis samples. The clinical utility of the method was successfully tested in a patient with traumatic brain injury. In paper II we evaluated microdialysis as an in vivo method to characterize the relative kinetics of ROS-related metabolites in human skeletal muscle exposed to ischaemia-reperfusion. Results indicated that microdialysis was feasible and safe to use in monitoring metabolic events during tourniquet-assisted surgery. In paper III we investigated the association between an oxidative stress marker (urinary 8-iso-PGF2α) and bone mineral density (BMD) and whether α-tocopherol modified the association. The main finding was the negative association between 8-iso-PGF2α and BMD and that the association was further dependent on serum α-tocopherol level. In paper IV we performed a randomized controlled trial to evaluate the influence of Q10 supplementation on exercise performance and metabolites of muscular damage. We did not observe any effects on exercise capacity after 8 weeks of Q10 administration. Nor did we find a significant effect on serum markers related to oxidative stress. In conclusion we have studied the influence of oxidative stress on muscle and bone in vivo in humans. The oxidative stress was triggered by four different causes (trauma, ischemia-reperfusion, ageing, and exercise exhaustion).
15

Penetrační vlastnosti polymerních micel na bázi hydrofobizované kyseliny hyaluronové. / The penetration features of the hydrofobized hyaluronic acid – based polymeric micelles.

Mischingerová, Monika January 2014 (has links)
The aim of this thesis was to investigate the penetration features of the hydrofobized hyaluronic acid – based polymeric micelles using Nile red as carried tracer. Furthermore, to implement basic characterization of polymeric micelles for potential cosmetic applications using Coenzyme Q10 (CoQ10) as carried substance. It was found that the size of the polymeric micelles with carried CoQ10 did not exceed 100 nm. Applied delivery systems based on hydrophobic hyaluronic acid were suitable for potential topical application. Delivery systems with Nile Red as carried tracer demonstrated excellent penetration features. We assume that delivery systems with CoQ10 will exhibit similar penetration features. An issue has appeared whether the carrier breaks or proceeds along with NR to the skin. Moreover, another experiments have been designed which could also verify the penetration features of these systems.
16

Development of an inhalational formulation of Coenzyme Q₁₀ to treat lung malignancies

Carvalho, Thiago Cardoso 14 February 2012 (has links)
Cancer is the second leading cause of death in the United States and its onset is highly incident in the lungs, with very low long-term survival rates. Chemotherapy plays a significant role for lung cancer treatment, and pulmonary delivery may be a potential route for anticancer drug delivery to treat lung tumors. Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. In this work, we hypothesize that formulations of CoQ10 may be developed for pulmonary delivery with a satisfactory pharmacokinetic profile that will have the potential to improve a pharmacodynamic response when treating lung malignancies. The formulation design was to use a vibrating-mesh nebulizer to aerosolize aqueous dispersions of CoQ₁₀ stabilized by phospholipids physiologically found in the lungs. In the first study, a method was developed to measure the surface tension of liquids, a physicochemical property that has been shown to influence the aerosol output characteristics from vibrating-mesh nebulizers. Subsequently, this method was used, together with analysis of particle size distribution, zeta potential, and rheology, to further evaluate the factors influencing the capability of this nebulizer system to continuously and steadily aerosolize formulations of CoQ₁₀ prepared with high pressure homogenization. The aerosolization profile (nebulization performance and in vitro drug deposition of nebulized droplets) of formulations prepared with soybean lecithin, dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) were evaluated. The rheological behavior of these dispersions was found to be the factor that may be indicative of the aerosolization output profile. Finally, the pulmonary deposition and systemic distribution of CoQ₁₀ prepared as DMPC, DPPC, and DSPC dispersions were investigated in vivo in mice. It was found that high drug amounts were deposited and retained in the mouse lungs for at least 48 hours post nebulization. Systemic distribution was not observed and deposition in the nasal cavity occurred at a lower scale than in the lungs. This body of work provides evidence that CoQ₁₀ may be successfully formulated as dispersions to be aerosolized using vibrating-mesh nebulizers and achieve high drug deposition in the lungs during inhalation.

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