Browsing by Subject "Oxidative stress"

Now showing 1 - 7 of 7
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    Adipocyte protein carbonylation and oxidative stress in obesity-linked mitochondrial dysfunction and insulin resistance.
    (2011-09) Curtis, Jessica Marie
    Carbonylation is the covalent, non-reversible modification of the side chains of cysteine, histidine and lysine residues by lipid peroxidation end products such as 4-hydroxy- and 4-oxononenal. The antioxidant enzyme glutathione S-transferase A4 (GSTA4) catalyzes a major detoxification pathway for such reactive lipids but its expression was selectively down regulated in the obese, insulin resistant adipocyte resulting in increased protein carbonylation. The effects of such modifications are associated with increased oxidative stress and metabolic dysregulation centered on mitochondrial energy metabolism. Mitochondrial functions in adipocytes of lean or obese GSTA4 null mice were significantly compromised compared to wild type controls and were accompanied by an increase in superoxide anion. Silencing GSTA4 mRNA in cultured adipocytes resulted in increased protein carbonylation, increased mitochondrial ROS, dysfunctional state 3 respiration and altered glucose transport and lipolysis. To address the role of protein carbonylation in the pathogenesis of mitochondrial dysfunction quantitative proteomics was employed to identify specific targets of carbonylation in GSTA4-silenced or overexpressing 3T3-L1 adipocytes. GSTA4- silenced adipocytes displayed elevated carbonylation of several key mitochondrial proteins including the phosphate carrier protein, NADH dehydrogenase 1 alpha subcomplexes 2 and 3, translocase of inner mitochondrial membrane 50, and valyl-tRNA synthetase. Elevated protein carbonylation is accompanied by diminished complex I activity, impaired respiration, increased superoxide production and a reduction in membrane potential without changes in mitochondrial number, area or density. These results suggest protein carbonylation plays a major instigating role in mitochondrial dysfunction and may be a linked to the development of insulin resistance in the adipocyte.
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    The effect of intake of whole grain and whole grain components on type 2 diabetes in rats.
    (2012-02) Youn, Moon Yeon
    Consumption of whole grains has been associated with reduced risk of type 2 diabetes epidemiologically. However, studies of the effect of individual whole grains on the development of type 2 diabetes are lacking. The objective of this research was to examine the effect of consumption of whole grains and a processed whole grain component on type 2 diabetes in diabetic rats. The first study was designed to investigate the effect of various whole grains consumption on diabetic control and progression in an animal model of type II diabetes, the Goto-Kakisaki (GK) rat. In this study, whole grain consumption showed only slight improvements in glucose control and insulin resistance early in the progression of diabetes, improvements which were lost with time, and no improvement in a marker of oxidative stress. The slight effect of whole grain consumption on slowing the progression of type 2 diabetes may be due to poor bioavailability of nutrients and phytochemicals. Thus, it was hypothesized that consumption of a processed whole grain ingredient with increased bioavailability of nutrients and phytochemicals might improve the diabetic state. The purpose of the second study was to examine the effect of processed wheat bran consumption on metabolic parameters related to diabetes and obesity in an animal model of type 2 diabetes with obesity, the Zucker diabetic fatty (ZDF) rat. The consumption of processed wheat bran had highly beneficial effects on the diabetic state, including decreasing the insulin response after a meal, decreasing visceral fat pad weight, insulin resistance, and plasma and liver cholesterol, and increasing bile acid excretion. The finding of correlations between ferulic acid, the major phenolic in wheat, in plasma and urine and metabolic parameters related to diabetes suggests that increased bioavailability of ferulic acid is responsible for the improvements seen in these parameters. In conclusion, whole grain intake provided a modestly beneficial effect on the development of type 2 diabetes. However, processing of a whole grain component, wheat bran, to increase the bioavailability of active compounds in the bran resulted in highly significant improvements in the diabetic state in an animal model of type 2 diabetes with obesity.
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    The effects of two modes of exercise training on plasma biomarkers of inflammation and oxidative stress in patients with symptomatic peripheral artery disease
    (2014-08) Salisbury, Dereck Lee
    Introduction: Peripheral Artery Disease (PAD) is a manifestation of progressive atherosclerosis involving the main conduit arteries supplying the lower extremities. It is well known that atherosclerotic cardiovascular disease including PAD, is related partly to vascular inflammation and oxidative stress. Treadmill walking exercise to moderate claudication pain is considered the gold standard for improving walking distance in patients with PAD and claudication. Our group had previously reported that non-ischemia inducing upper body ergometry exercise training improves pain-free and maximal walking distance similar to ischemic inducing treadmill exercise training in patients with claudication. The influence of ischemic and non-ischemic inducing exercise training on systemic inflammation and vascular oxidative stress remains to be fully elucidated. Methods: A total of 75 patients (59 male and 16 female) with symptomatic PAD from the randomized controlled trial, Exercise Training to Reduce Claudication (EXERT), were used in a secondary analysis of inflammation and oxidative stress. Analysis of plasma for TNF alpha, IL-10, and F2 Isoprostane were performed at baseline and following 12 weeks of moderate intensity, claudication inducing treadmill training (T), upper body ergometry training (UBE), or usual care (C). Analysis of covariance was used to evaluate changes among groups for all biomarkers following intervention, using baseline level as a covariate. Pearson's correlation coefficient was used to assess correlation among baseline plasma biomarkers and physical and physiological variables. Results: After 12 weeks of intervention, all patients, regardless of the group increased TNF alpha levels. In particular, patients randomized to the UBE group significantly increased TNF alpha levels compared to the control group after adjusting for baseline TNF alpha and allopurinol (a significant covariate). Participants in the treadmill group had non-significant increases in IL-10, while all groups showed non-significant decreases in F2 Isoprostanes. Additionally there was no significant correlation between baseline plasma inflammatory and oxidative stress biomarkers, with physical and physiological variables such as ankle-brachial index, pain-free walking distance, and maximal walking distance at baseline. However, body mass index was significantly correlated to baseline TNF alpha levels (r=0.228, p=0.05). Conclusion: Moderate intensity UBE training appears to significantly increase the proinflammatory cytokine TNF alpha compared to a control group in patients with symptomatic PAD. However, all groups increased TNF alpha after 12 weeks of intervention, which contradicts the deemed anti-inflammatory effect of aerobic exercise training. It is clear that further study is required to establish if exercise training in patients with claudication is anti-inflammatory.
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    Mitigating oxidative stress in childhood cerebral adrenoleukodystrophy -an investigation of N-acetylcysteine pharmacology
    (2014-02) Zhou, Jie
    Adrenoleukodystrophy (ALD) is an X-linked genetic disorder which affects the adrenal glands, peripheral neuronal system, the spinal cord and white matter of central nervous system (CNS). It is a progressive neurology disorder with incidence of 1 in 17,000 newborns. ALD is caused by mutations in the ABCD1 gene, which encodes the peroxisomal membrane transporter for transporting very long chain fatty acids (VLCFAs) into peroxisomes for degradation. As a result, VLCFAs accumulate in the plasma and tissues of ALD patients. Elevated VLCFAs along with ABCD1 gene mutations are used for the diagnosis of ALD. ALD has various clinical phenotypes. Childhood cerebral adrenoleukodystrophy (CCALD) is the cerebral form of ALD that affects young boys (4~10 years of age), causing progressive, debilitating effects on the CNS leading to death within a few years. The pathophysiology of CCALD is only partially understood, but it is known that VLCFAs accumulate in the plasma, brain and other tissues in CCALD patients, which can cause oxidative stress and downstream neurodegeneration. Recently, oxidative stress, the accumulation of free radicals (reactive molecules), has been shown to cause CNS neurodegeneration and play a major role in CCALD pathophysiology. Currently, the most successful treatment for CCALD is hematopoietic stem cell transplantation (HSCT), which halts disease progression and extends life when CCALD is treated early. But it is much less effective for late-stage CCALD. Based on evidence that oxidative stress plays a role in the disease, the Blood and Marrow transplantation group at University of Minnesota has utilized N-acetylcysteine (NAC) as adjunctive therapy together with HSCT in late-stage CCALD. This combinatorial approach has improved survival rate from 36% to 84% compared to HSCT only in a cohort study (Miller et al., 2011). However, NAC's mechanisms of action are still unclear in CCALD patients. As an FDA-approved drug, NAC is used as an antidote for acetaminophen overdose and as a mucolytic agent to reduce symptoms associated with cystic fibrosis. It has gained renewed attention as a potential therapy for a number of conditions including pulmonary, neurological, psychiatric, and cardiovascular diseases. With a long history of clinical use, several mechanisms including antioxidative and anti-inflammatory activities have been proposed as the basis for its therapeutic effects. However, the exact molecular mechanism by which NAC improves the survival rate of CCALD patients is still unclear. And this missing piece of information, which is the basis for my research work, is required to further optimize the therapy. In my thesis, four research projects were designed and implemented to address the pharmacology of NAC in CCALD related biological models. The first study was to investigate the downstream signaling molecules induced by NAC in the plasma of CCALD patients. Heme oxygenase-1 (HO-1) and ferritin were examined in CCALD patients before and after NAC exposure. Based on the clinical study results that the expression of HO-1 and downstream ferritin were induced by NAC, the second study was further designed in oligodendrocytes, which are CNS glial cells and closely related to demyelination and neurodegneration, to investigate the cytoprotective role of HO-1 induced by NAC. Moreover, we also tried to delineate the role of accumulation of VLCFAs in CCALD and its relationship with oxidative stress and mitochondria. The third study was designed in oligodendrocytes to investigate whether mitochondria and oxidative stress status are affected by pathophysiological concentrations of VLCFAs and if so, whether NAC could be used to reverse this condition. Finally, the fourth pharmacokinetic/pharmacodynamics study was designed and implemented in wild-type mice to address the relationship between NAC concentration and pharmacodynamic endpoints in vivo. This study is also critical to determine the biotransformation of NAC in vivo.The results from my studies indicate HO-1 as the newly discovered downstream mediators for NAC action. Studies also show for the first time that depletion of mitochondrial glutathione (mtGSH) is the pathological cause for CCALD, and that targeting mitochondrial dysfunction can be a potential effective intervention for CCALD patients. In addition, GSH levels, redox ratio, HO-1 and ferritin levels can serve as biomarkers or pharmacodynamic endpoints to evaluate NAC efficacy. In the long term, characterization of NAC mechanisms of action will help to optimize therapy in CCALD patients. In addition, the information generated from my studies on the efficacy of NAC in CCALD is also applicable to other neurodegenerative disorders sharing similar pathologies such as Gaucher's disease, multiple Sclerosis, Alzheimer's disease etc.
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    Pharmacology and Clinical Effects of N-acetylcysteine in Neurodegenerative Disorders
    (2015-08) Holmay, Mary
    Free radicals and other reactive oxygen species (ROS) constitute a normal part of the intracellular environment. Endogenous enzymes such as catalase, superoxide dismutase and the thiol redox systems, glutathione and oxidized glutathione, serve as reducing agents to minimize the harm ROS might cause in the cell. An excess of ROS, however, can tilt the delicate balance leading to oxidative stress. It is now well known that oxidative stress (OS) plays an important role in many neurodegenerative disorders such as Parkinson disease, Alzheimer’s disease, amyotrophic lateral sclerosis and other disorders with neurodegenerative effects, including adrenoleukodystrophy (ALD). Many antioxidants have been studied in an effort to ameliorate the oxidative stress, slow the progression or treat the symptoms of these and other neurodegenerative disorders, mostly with limited success. The potential reasons for the limited success of these compounds are discussed in this thesis, and the dissertation research on the potential use of N-acetylcysteine, (NAC) a well-known antioxidant and glutathione precursor, is described in detail. The first portion of the dissertation research described herein focused on characterizing the pharmacokinetics of intravenously administered NAC as adjunctive therapy with hematopoietic cell transplant (HCT) in ALD. The objectives of this research were to characterize the pharmacokinetics of i.v. NAC and to explore one of the mechanisms by which NAC is thought to exert its antioxidant effects: through the provision of cysteine for the synthesis of glutathione, the most powerful endogenous antioxidant in the body. The second clinical study described in this thesis focused on the effect of i.v. administered NAC on glutathione concentrations measured directly in the brain of people with Parkinson’s disease, Gaucher disease and healthy control subjects, through the use of magnetic resonance spectroscopy. The research described in this dissertation represents the first report of the pharmacokinetics and direct pharmacodynamic effects of i.v. NAC administration in those affected by disorders of neurodegeneration. This research now serves as the basis for other pharmacokinetic and pharmacodynamic studies of NAC in other populations as well as with other dosage forms and formulations, with the hope of developing effective antioxidant treatments for those suffering from neurodegenerative disorders.
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    SELEX-sequencing
    (2016) Ryan, Courtney; Lacher, Sarah E; Slattery, Matthew; Slattery, Matthew; Lacher, Sarah E.
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    Sequence Determinants of Nrf2 Regulatory Output
    (2015) Ryan, Courtney; Lacher, Sarah E.; Slattery, Matthew