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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

Regrese koronární aterosklerózy při hypolipidemické terapii / The coronary atherosclerosis regression during hypolipidemic therapy

Kovárník, Tomáš January 2012 (has links)
Background: There is no study focusing on changes of coronary atherosclerosis during dual hypolipidemic therapy with statin and ezetimibe. Methods: 107 patients with stable angina were enrolled and the final analysis was performed in 89 patients. Randomization was 1:1 to the group A (atorvastatin 80mg and ezetimibe 10mg) and to the standard group S. Treatment period was 12 months. Results: Changes of percent atheroma volume (PAV) were -0,4% in group A and + 1,4% in group S, p=0,014. Combine atherosclerosis regression (increase of lumen volume together with decrease of PAV) was found more frequent in group A (40,5%) than the group S (14,9%), p=0,007. The target LDLc level < 2mmol/l, presence of at least four of five atherosclerotic risk factors, and decrease of VCAM level were independent predictors for plaque regression. There were no significant differences in plaque composition between the two groups over the duration of the study. However during analysis the two groups together, fibrous and fibro-fatty tissues decreased and dense calcification and necrotic core increased during follow-up. Conclusion: The dual hypolipidemic therapy starts atherosclerosis regression. Despite significant decrease of lipid levels the continuous plaque shift from fibro and fibro-fatty to necrotic with calcification...
52

Are Statins Protective or Harmful to Cognitive Function?

Mospan, Cortney M. 01 January 2016 (has links)
In February 2012, the FDA issued safety label changes and monitoring requirements for statin therapy. A risk of cognitive impairment was noted, although evidence was largely based on observational data, including case reports. In 2014, the National Lipid Association's safety task force found that evidence does not support cognitive decline as a classwide effect for statins. Some evidence has shown that statins may actually have beneficial effects on cognition. This article discusses management of statin therapy in patients with cardiovascular risk who may experience cognitive decline or have cognitive impairment, such as Alzheimer disease.
53

Statins and Risk of Alzheimer Disease: A Systematic Review and Meta-Analysis

Severin, Kimberley January 2012 (has links)
No description available.
54

Elevated Troponin in the Absence of Acute Coronary Syndrome

Poe, Stacy A. 27 September 2013 (has links)
No description available.
55

The effect of simvastatin and pitavastatin on insulin secretion from clonal pancreatic ß-cells (INS-1)

Abdul-Akbar, Princess Maryam 13 February 2024 (has links)
OBJECTIVE: The 10th leading cause of death in the United States is heart disease. Most of the deaths by heart disease has a correlation with an occlusion of the coronary arteries. While diabetes mellitus is currently the 7th leading cause of death, which is a chronic condition that affects more than 37 million people in America. The global epidemic of obesity largely explains the dramatic increase in the incidence and prevalence of type 2 diabetes (T2D) over the past 25 years. Statins are well known drugs to decrease LDL for individuals who suffer from hypercholesterinemia; however, there is also an increased risk of developing diabetes mellitus. An estimation of 10-20 per 10,000 patients per year demonstrated an excess risk of T2D with the long-term use of statin. Here we examine the effects of simvastatin and pitavastatin on pancreatic ß-cell function to determine whether altered insulin secretion may contribute to an increased risk of T2D. METHODS: The experiments were performed using clonal pancreatic ß-cells (INS-1). The cells were grown in 4 mM glucose in RPMI media. Cells were grown for three days before adding the different types of statins: simvastatin and pitavastatin for one day. Then the cells were used to perform the glucose-induced insulin secretion (GSIS) experiment. Insulin secretion and insulin content were assay using a fluorescence-based immunoassay. The study was calculated using Microsoft Excel. Standard variance and standard error were used to assess the difference sets of data. RESULTS: INS-1 cells responded to acute glucose stimulation after chronic culture in both low (4 mM) and high (11 mM) glucose. Secretion from cells cultured at 4 mM glucose was higher than cells cultured at 11 mM glucose at all glucose concentrations tested, characteristic of the effects of glucolipotoxicity (GLT). Insulin content in cells cultured at high glucose was decreased 8.6-fold compared to cells cultured at the more physiological low glucose condition. When normalized to basal secretion cells cultured at high glucose exhibited basal hypersecretion and increased GSIS compared to those in low glucose. Simvastatin (100 nM, 24 hrs) increased basal insulin secretion to a greater extent than Pitavastatin. The effects of pitavastatin on basal insulin secretion were less consistent than seen with simvastatin. Simvastatin was also shown to inhibit GSIS from cells cultured at 4 mM glucose, while pitavastatin increased GSIS. CONCLUSION: Both pitavastatin and simvastatin alter insulin secretion from pancreatic ß-cells. The effect of simvastatin to both increase basal and decrease GSIS, characteristic of GLT suggests pitavastatin may be the statin of choice to reduce the risk of statin-induced T2D.
56

IN VITRO EFFECT OF STATINS ON STREPTOCOCCUS MUTANS, STREPTOCOCCUS SANGUIS, AND STREPTOCOCCUS SALVARIUS

Alshammari, Abdulaziz January 2016 (has links)
Objectives: Cardiovascular disease (CVD), including heart attack, angina, and stroke, is ranked as the number one cause of mortality world wide. High blood cholesterol is linked to CVD and is an important risk factor. Statins – cholesterol lowering drugs- are first choice drugs for reducing the chance of suffering a CVD event. In the USA alone, approximately 32 million individuals take statins. Although randomized control trials of statins have demonstrated their efficacy in preventing CVD, much less information has been reported on their unintended effects. Although not thought of traditionally as antimicrobials, statins have been shown to have antimicrobial effects in vitro. The statins belong to a family of drugs that lower cholesterol levels by inhibiting 3-hydroxy-3-methylglutaryl-CoA reductase, a rate limiting enzyme in the human mevalonate pathway of which cholesterol in the biosynthetic end product. The mevalonate pathway is an important cellular metabolic pathway present in many bacteria. Hence, the aim of this study was to assess the in vitro efficacy of statins against selected strains of oral streptococci, as determined by the minimum inhibitory concentration. A second related objective is to assess the in vitro effect of statins on single species biofilm formation , as determined by binding of the same streptococci to hydroxyapatite pegs. Methods: The effect of statins on S. mutans, S. sanguis, and S. salivarius was determined by finding the minimum inhibitory concentration (MIC) by broth dilution assays. Simvastatin, pravastatin atorvastatin, and rousuvastatin were used in this study. The minimum inhibitory concentration was considered to be the lowest concentration of statin that prevented bacterial growth, i.e. a clear test tube. Experiments were repeated twice for each bacterial species. The effect of simvastatin, atorvastatin, and pravastatin on the ability of S. mutans and S. sanguis to form single species biofilm was assayed using sterile microplates and the MBEC Biofilm Inoculator (Innovatech). Results: Two trials indicated that the MIC of simvastatin against the selected oral bacteria was determined to be 15.6 μg/ml for S. mutans and S. sanguis, and 7.8 μg/ml for S. salivarius. The MIC of rosuvastatin and atorvastatin was determined to be 100 μg/ml against all three streptococci, whereas the MIC of pravastatin was even higher (200 μg/ml) against all three streptococci. Likewise, two trials indicated that statins decreased single species biofilm formation by S. mutans and S. sanguis. For simvastatin, biofilm formation was decreased by concentrations eight fold below the MIC . The results were substantiated by spectrophotometric assay . For atorvastatin and pravastatin, biofilm formation was decreased by concentrations 3-4 fold below the MIC. Conclusions: These experiments demonstrate the in vitro antimicrobial effect of statins on S. mutans, S.sanguis, and S. salivarius. The data indicate that the statins inhibit growth of the test organisms with MIC’s ranging from 7.8-200 μg/ml. Simvastatin has in vitro efficacy against the specific strains of bacteria used in this study at concentrations slightly less than the observed MIC’s of 15.6-7.8 μg/ml . The MIC’s for atorvastatin, pravastatin, and rosuvastatin are much higher than simvastatin, in the range of 100-200 μg/ml . The effects of statins on biofilm parallels the effect on growth of the bacteria. / Oral Biology
57

Determining a Rodent Model to Investigate Glutamate as a Mechanism Underlying Statin Myalgia

Schweitzer, Allyson January 2020 (has links)
HMG-CoA reductase inhibitors, known commonly as statins are one of the most widely prescribed medications worldwide. Statins reduce circulating cholesterol levels and are very effective at reducing one’s risk for all-cause and cardiovascular mortality. Though generally well tolerated, statin-associated muscle symptoms (SAMS) present in more than a quarter of statin users. The most common SAMS is myalgia or muscle pain. Statin myalgia often presents in the absence of myofibre damage, making its origin and treatment ambiguous. There are numerous rodent models for statin myopathy in the literature, but surprisingly there is no representation of statin myalgia that we are aware of. This is shocking given the high prevalence of statin myalgia compared to statin myopathy. Recently, our lab published an in vitro model of statin myalgia that focused on elevated xCT transporter activity and interstitial glutamate. This model explains that pain perceived in statin myalgia is the result of statins’ downstream ability to elevate skeletal muscle interstitial glutamate concentrations, thereby activating peripheral nociceptors. The studies herein aimed to create an in vivo rodent model of statin myalgia based on the aforementioned in vitro model. We hypothesized that glutamate, sampled by way of skeletal muscle microdialysis, would be elevated in the skeletal muscle interstitium of rats following statin treatment. Drawing conclusions on the role of glutamate in statin myalgia was not a straightforward process and required multiple model adjustments due to confounding variables. Additionally, many of the recognized effects of statins that were assumed from human and in vitro studies did not translate well to our rodent model. This was the first attempt at creating an in vivo model of statin myalgia and evidence suggests that a rodent model may not be an appropriate representation of what occurs in humans. While these studies also raised doubt on the efficacy of rodent models for SAMS investigations in general and highlighted the importance of having standardized models, certain limitations and assumptions of our model must be addressed before concrete conclusions can be drawn. / Thesis / Master of Science in Medical Sciences (MSMS) / Statins, a class of cholesterol-lowering medications, are one of the most widely prescribed medications worldwide. They have been demonstrated to be very effective at reducing one’s risk of cardiovascular-related death. Statins are generally very well tolerated, however, the most common negative side effects of their use are muscle related and include muscle pain, muscle inflammation and muscle damage. Muscle pain is the most common of these symptoms to present and interestingly, often presents without any clinical indication of muscle damage. The lack of a physical explanation for what is causing this pain makes treating statin-associated muscle pain quite difficult. A lot of effort has gone into determining the mechanism(s) for statin-associated muscle damage, however, there is a gap when it comes to investigating the mechanism(s) for statin-associated muscle pain. The studies herein, therefore, aimed to bridge this gap and investigated a potential mechanism for statin-associated muscle pain in a rodent model. The foundation for this model was built on a cell culture model that was previously developed in our lab. Our data suggest that a rodent model for statin-associated muscle pain may not be an appropriate representation of what occurs in humans. In particular, reduced blood cholesterol and substantial skeletal muscle oxidative stress were not demonstrated in our model as they have been in humans and in cell culture studies. This raised concern around the efficacy of rodent models for statin associated muscle symptoms in general and highlighted the importance of having standardized models. The differences between human/cell culture studies and rodent models also made it difficult to draw firm conclusions on whether the mechanism for statin myalgia investigated herein is supported.
58

The effect of statins on bone and mineral metabolism

Maritz, Frans Jacobus 04 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The Effect of Statins on Bone and Mineral Metabolism Both statins and amino-bisphosphonates reduce the prenylation of proteins which are involved in cytoskeletal organization and activation of polarized and motile cells. Consequently statins have been postulated to affect bone metabolism. We investigated the effects of different doses of simvastatin (1,5,10 and 20mg/Kg/day), administered orally over 12 weeks to intact female Sprague-Dawley rats, and the effect of simvastatin 20mg/Kg/day in sham and ovariectomised rats, on femoral bone mineral density (BMD) and quantitative bone histomorphometry (QBH), compared to controls. Similarly, the affect of atorvastatin (2,5mg/Kg/day) and pravastatin (10mg/Kg/day) on BMD was investigated and compared to controls. BMD was decreased by simvastatin 1mg/Kg/day (p = 0.042), atorvastatin (p = 0,0002) and pravastatin (p = 0.002). The effect on QBH parameters differed with different doses of simvastatin (ANOVA; p = 0.00012). QBH parameters of both bone formation and resorption were equivalently and markedly increased by simvastatin 20mg/Kg/day in two independent groups of intact rats, and reflected by a relatively unchanged BMD. At lower doses, simvastatin 1mg/Kg/day decreased bone formation while increasing bone resorption as reflected by a marked decrease in BMD. Ovariectomised animals receiving simvastatin 20mg/Kg/day showed no change in BMD relative to the untreated ovariectomised controls, their increase in bone formation was smaller than in sham-operated rats receiving simvastatin and there was no change in bone resorption. The dose response curves of simvastatin for bone formation and resorption differed from each other. From these studies it is concluded that:- a) low-dose simvastatin (1mg/Kg/day), atorvastatin 2.5mg/Kg/day) and pravastatin 10mg/Kg/day) decrease BMD in rodents;b) 1mg/Kg/day simvastatin decreases bone formation and increases bone resorption and is reflected by a reduced BMD; c) 20mg/Kg/day simvastatin increases bone formation and resorption and results in an unchanged BMD; d) the effects of simvastatin on QBH differ at different dosages; e) the dose-response curves for QBH parameters of bone resorption and bone formation differ from each other; f) the effects of simvastatin seen in intact rats are not observed in ovariectomised rats; g) simvastatin is unable to prevent the bone loss caused by ovariectomy. / AFRIKAANSE OPSOMMING: Die Effek van Statiene op Been en Mineraal Metabolisme Beide statiene en aminobisfosfonate verminder die prenelasie van proteïene wat betrokke is in die sitoskeletale organisasie en aktivering van gepolariseerde en beweeglike selle. Gevolglik is dit gepostuleer dat statiene ‘n invloed sal hê op been metabolisme. Ons het die effekte van verskillende dossisse van simvastatien (1, 5, 10 en 20mg/Kg/dag), mondelings toegedien oor 12 weke aan intakte vroulike Sprague-Dawley rotte, en die effek van simvastatien 20mg/Kg/dag op skyn- en ge-ovariektomeerde rotte, op femorale been mineral digtheid (BMD) en kwantitatiewe been histomorfometrie (KBH), vergeleke met kontroles, ondersoek. Op ‘n soortgelyke manier is die effek van atorvastatien (2,5mg/Kg/day) en pravastatien (10mgKg/dag) op BMD ondersoek en vergelyk met kontroles. BMD is verminder deur simvastatien 1mg/Kg/dag (p = 0.042), atorvastatien (p = 0.0002) en pravastatien (p = 0.002). Die effekte op KBH parameters het verskil met verskillende dossisse van simvastatien (ANOVA; p = 0.00012). KBH parameters van beide been vormasie en resorpsie is vergelykend en merkbaar verhoog deur simvastatien 20mg/Kg/dag in twee onafhanklike groepe van intakte rotte en is vergesel deur ‘n relatiewe onveranderde BMD. Met laer dossisse het simvastatien 1mg/Kg/dag been vormasie verminder terwyl been resorpsie verhoog is en is weerspieël deur ‘n merkbaar verminderde BMD. Ge-ovariektomeerde diere wat simvastatien 20mg/Kg/dag ontvang het, het geen verandering in BMD relatief tot die onbehandelde geovariektomeerde kontroles getoon nie, en die toename in been vormasie was kleiner as in die skyngeopereerde rotte wat simvastatien ontvang het en daar was geen verandering in been resorpsie nie. Die dosis-respons kurwes vir simvastatien vir been vormasie en resorpsie het van mekaar verskil. Uit hierdie studies word die volgende gevolgtrekkings gea) lae-dosis simvastatien (1mg/Kg/dag), atorvastatien 2.5mg/Kg/dag en pravastatien 10mg/Kg/dag verminder BMD in knaagdiere; b) 1mg/Kg/dag simvastatien verminder been vormasie en verhoog been resorpsie en veroorsaak gevolglik ‘n velaging in die BMD; c) 20mg/Kg/dag simvastatien verhoog been vormasie en resorpsie met ‘n gevolglike onveranderde BMD; d) die effekte van simvastatien op KBH verskil met verskillende dossisse; e) die dosis-repons kurwes van been resorpsie en been vormasie veskil van mekaar f) die effekte van simvastatien wat waargeneem in intakte rotte word nie gesien in ge-ovariektomeerde rotte nie; g) simvastatien kannie die verlies van been wat veroorsaak word deur ovariektomie voorkom nie.
59

Human Vascular Microphysiological Systems for Drug Screening

Fernandez, Cristina Elena January 2016 (has links)
<p>Endothelial dysfunction is the predominant pathophysiological state prior to the onset of atherosclerosis. Currently, treatments for endothelial dysfunction are evaluated in vitro using two-dimensional (2D) cell culture assays or in vivo animal models. Microphysiological systems are small-scale three-dimensional (3D) tissue models that recapitulate the native tissue structure and function. An ideal microphysiological system is comprised of human cells embedded within a 3D matrix introduced to physiological fluid perfusion. Immune challenge in the form of cytokines or immune cells further recapitulates the native microenvironment.</p><p>A vascular microphysiological system was developed from a small-diameter tissue engineered blood vessel (TEBV) in a perfusion culture circuit. TEBVs were created from collagen gels embedded with human neonatal dermal fibroblasts and plastically compressed to yield collagen constructs with high fiber densities. TEBVs are rapidly producible and can be directly introduced into perfusion culture immediately after fabrication. Endothelium-independent vasoconstriction in response to phenylephrine and endothelium-dependent vasodilation in response to acetylcholine were used to analyze the health and function of the endothelium non-destructively over time.</p><p>Endothelial dysfunction was induced through introduction of the pro-inflammatory cytokine tumor necrosis factor – α (TNF-α). Late-outgrowth endothelial progenitor cells derived from the peripheral blood of coronary artery disease patients (CAD EPCs) were evaluated as a potential endothelial source for autologous implantation in both a two-dimensional (2D) direct co-culture model as well as a 3D model as an endothelial source for a tissue engineered blood vessel. CAD EPCs demonstrated similar adhesive properties to a confluent, quiescent layer of smooth muscle compared to human aortic endothelial cells. Within the TEBV system, CAD EPCs demonstrated the capacity to elicit endothelium-dependent vasodilation. CAD EPCs were compared to adult EPCs from young, healthy volunteers. Both CAD EPCs and healthy volunteer EPCs demonstrated similar endothelium-dependent vasoactivity in response to acetylcholine; however, in response to TNF-α, CAD EPCs demonstrated a reduced response to phenylephrine at high doses.</p><p>The treatment of TEBVs with statins was explored to model the drug response within the system. TEBVs were treated with lovastatin, atorvastatin, and rosuvastatin for three days prior to exposure to TNF-α. In all three cases, statins prevented TNF-α induced vasoconstriction in response to acetylcholine within the TEBVs, compared to TEBVs not treated with statins. Overall, this work characterizes and validates a novel vascular microphysiological system that can be tested in situ in order to determine the effects of various patient populations and drugs on endothelial health and function under healthy and inflammatory conditions.</p> / Dissertation
60

The effect of fluvastatin on mast cell function: genotype dependence

Kolawole, Elizabeth M 01 January 2014 (has links)
Fluvastatin, the HMG-CoA reductase inhibitor known for its role in the treatment of hypercholesterolemia and cardiovascular disease, has more recently been shown to play a role in the immune response. Given the critical role that mast cells play in allergy and inflammatory diseases such as asthma, which effects one third of America’s population, we assessed the effect of fluvastatin on mast cell and basophils function. We demonstrate that fluvastatin downregulated IgE-mediated cytokine production. Additionally, in vivo studies showed that fluvastatin suppressed IgE-mediated anaphylaxis. Interestingly, the effects of fluvastatin showed dependence on genetic background, as C57BL/6 mast cells were sensitive, while 129/Sv mast cells were resistant to fluvastatin. Characterizing the role of fluvastatin on mast cells may prove to be therapeutically important.

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