As doenças denominadas como negligenciadas têm causado nos últimos anos uma preocupação muito acentuada na comunidade científica e para as autoridades de saúde, relacionada às suas terapêuticas, no sentido de que os medicamentos existentes não se apresentam totalmente eficazes, além de determinarem efeitos colaterais extremamente elevados. Nesse perfil se encaixam a doença de Chagas e as Leishmanioses, etiologias determinadas respectivamente por Trypanosoma cruzi e parasitas do gênero Leishmania. Como proposta de encontrarmos uma alternativa para o tratamento dessas parasitoses, avaliamos o potencial terapêutico de três estatinas (sinvastatina, pravastatina e mevastatina), comercialmente encontradas para o tratamento de níveis elevados de colesterol e triglicérides, baseado no princípio de que a rota bioquímica para a formação de colesterol é semelhante à do ergosterol, componente da membrana plasmática desses protozoários. Foram realizadas avaliações in vitro e in vivo das estatinas puras e de suas associações com o benzonidazol, medicamento de referência no tratamento da doença de Chagas e com a anfotericina B, medicamento de referência no tratamento das leishmanioses, partindo do pressuposto que a substituição do benzonidazol / anfotericina B ou a diminuição de suas doses em combinação com as estatinas, atuando como coadjuvantes, pudessem auxiliar no tratamento e diminuir os efeitos colaterais provocados pela medicação. Observou-se nos ensaios com T. cruzi in vitro boa atividade antiparasitária, com valores de porcentagem de lise celular mais altos ou comparados aos encontrados para o benzonidazol, já in vivo, apenas a mevastatina apresentou redução da parasitemia em relação ao controle positivo e às outras estatinas testadas. Nos ensaios com L. braziliensis e L. major não foi observado resultado significante, tanto in vitro como in vivo, apesar de em algumas situações encontrarmos resultados próximos ao controle positivo. / Over recent years, neglected diseases has been a problem to the scientific community and health associations due the absence of total efficacy of drugs, and by their potential side effects. Chagas\' disease and Leishmaniasis - both caused respectively by Trypanosoma cruzi and by parasites the genus Leishmania fit on this profile. Aiming to find an alternative treatment of these parasitosis we evaluated the potential therapeutic of three statins (simvastatin, pravatatin, and mevastatin) which are commercially employed for treatment of high levels of cholesterol and triglycerides, based on the similarity of the biochemical route of cholesterol and ergosterol formation, being the ergosterol a component of plasmatic membrane of these protozoa. In vitro and in vivo evaluation were made by the association of these statins with benznidazole and amphotericin B used for Chagas\' disease and Leishmaniasis treatment respectively, hypothesizing that the replacement of benznidazole/amphotericin B or the reduction of the doses in combination with statins as coadjuvants could provide better treatment and side effects reduction caused by the commercial drugs. In vitro assays under T. cruzi showed significant antiparasitic activity when compared with benzonidazole to all statins. On the other hand in vivo assays showed parasitic reduction only by mevastatin when it was compared with positive control. L. braziliensis and L. major in in vivo assay didn´t show significant results despite the results have been similar to the positive control.

As estatinas são substâncias que inibem a síntese de colesterol. Por não existir métodos analíticos simples e de baixo custo para determinação quantitativa de pravastatina sódica, fluvastatina sódica, atorvastatina cálcica e rosuvastatina cálcica, o objetivo desta pesquisa foi desenvolver, validar e comparar os métodos por cromatografia líquida de alta eficiência e espectrofotometria direta e derivada no ultravioleta para a determinação quantitativa de estatinas em comprimidos. Os métodos cromatográficos foram realizados em coluna LiChrospher® RP-18 com fase móvel composta de metanol-água e pH ajustado a 3,0 com ácido fosfórico. Os métodos espectrofotométricos foram validados utilizando NaOH 0,1 M como solvente. A análise estatística com os testes t e F, não mostraram diferença significativa entre os métodos propostos ao nível de confiança de 95%. Os métodos são simples, eficientes e podem ser utilizados em análises de rotina para o controle de qualidade de estatinas em comprimidos. / The statins are substances that inhibit the synthesis of cholesterol. There is no simple and low cost analytical methods for quantitative determination of pravastatin sodium, fluvastatin sodium, atorvastatin calcium and rosuvastatin calcium; the objective of this research was to develop, to validate and to compare the methods as high performance liquid chromatography and ultraviolet direct and derivative spectrophotometry for quantitative determination of statins in tablets. The chromatographic methods were carried out with a LiChrospherB RP-18 column with a mobile phase composed of methanol-water and pH adjusted to 3.0 with phosphoric acid. The spectrophotometric methods were validated using NaOH 0.1 M as solvent. The statistical analysis using tests t and F, did not show significant difference between the methods considering the 95% confidence level. The methods are simple, efficient and can be used in routine analyses for quality control of statins in tablets.

Wong, Mei Fung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 207-251). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.iv / ACKNOWLEDGEMENTS --- p.vi / PUBLICATIONS BASED ON WORK IN THIS THESIS --- p.vii / ABBREVIATIONS --- p.viii / TABLE OF CONTENTS --- p.x / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Diabetes Mellitus --- p.1 / Chapter 1.2 --- Structure and Functions of the Pancreas --- p.2 / Chapter 1.2.1 --- Size of Pancreatic β-Cells --- p.4 / Chapter 1.2.2 --- Signaling Pathways of Insulin Secretion from Pancreatic β-Cells --- p.4 / Chapter 1.3 --- Classification of Diabetes --- p.6 / Chapter 1.3.1 --- Type 1 Diabetes --- p.6 / Chapter 1.3.2 --- Type 2 Diabetes --- p.8 / Chapter 1.4 --- Pathologies of Type 2 Diabetes --- p.9 / Chapter 1.4.1 --- Hyperglycemia --- p.9 / Chapter 1.4.1.1 --- A dvanced Glycosylation End Products --- p.11 / Chapter 1.4.1.2 --- Protein Kinase C Activation --- p.13 / Chapter 1.4.1.3 --- The Glucosamine Pathway --- p.14 / Chapter 1.4.1.4 --- Oxidative Stress --- p.15 / Chapter 1.4.2 --- Insulin Resistance --- p.15 / Chapter 1.4.3 --- Loss of β-Cell Mass and β-Cell Dysfunction --- p.18 / Chapter 1.5 --- Complications of Diabetes Mellitus --- p.21 / Chapter 1.5.1 --- Cardiovascular Diseases --- p.21 / Chapter 1.5.2 --- Diabetic Retinopathy --- p.22 / Chapter 1.5.3 --- Diabetic Nephropathy --- p.23 / Chapter 1.5.4 --- Neuropathy --- p.24 / Chapter 1.6 --- Anti-Diabetic Drugs for Type 2 Diabetes Mellitus --- p.25 / Chapter 1.6.1 --- Secretagogues --- p.25 / Chapter 1.6.2 --- Sensitizers --- p.26 / Chapter 1.6.3 --- Alpha-Glucosidase Inhibitors --- p.27 / Chapter 1.6.4 --- Peptide Analogs --- p.27 / Chapter 1.6.4.1 --- Incretin Mimetics --- p.27 / Chapter 1.6.4.2 --- Dipeptidyl Peptidase-4 Inhibitors --- p.28 / Chapter 1.7 --- Insights of Porcine Islets in Treatment of Diabetics --- p.28 / Chapter 1.8 3 --- -Hydroxy-3-Methylglutaryl Coenzyme A Reductase (HMG CoA Reductase) --- p.31 / Chapter 1.8.1 --- Statins --- p.32 / Chapter 1.8.2 --- Pleiotropic Effects of Statins --- p.36 / Chapter 1.8.2.1 --- Statins and Isoprenylated Proteins --- p.36 / Chapter 1.8.2.2 --- Statins and Endothelial Functions --- p.38 / Chapter 1.8.2.3 --- Statins and Platelet Functions --- p.39 / Chapter 1.8.2.4 --- Statins and Plaque Stability --- p.39 / Chapter 1.8.2.5 --- Statins and Vascular Inflammation --- p.40 / Chapter 1.9 --- Clinical Studies of Statins on Diabetics --- p.41 / Chapter 1.10 --- Possible Factors Involved in Simvastatin-Regulated Insulin Secretion --- p.44 / Chapter 1.10.1 --- AMP-Activated Protein Kinase --- p.44 / Chapter 1.10.2 --- Caveolin-1 --- p.46 / Chapter 1.10.3 --- Sterol-Regulatory Elementary Binding Protein --- p.50 / Chapter 1.10.4 --- Protein Phosphatase 2A --- p.52 / Chapter 1.10.5 --- Calcium Sensing Receptor --- p.55 / Chapter 1.11 --- Objectives of Study --- p.59 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.60 / Chapter 2.1 --- Materials --- p.60 / Chapter 2.1.1 --- Solutions --- p.60 / Chapter 2.1.2 --- Antibodies --- p.63 / Chapter 2.2 --- Methods --- p.64 / Chapter 2.2.1 --- Maintenance of Pancreas Function --- p.64 / Chapter 2.2.2 --- Islet Isolation --- p.65 / Chapter 2.2.3 --- Hematoxylin and Eosin (H&E) Staining --- p.65 / Chapter 2.2.4 --- Simvastatin and Simvastatin-Na+ --- p.66 / Chapter 2.2.5 --- AICAR --- p.67 / Chapter 2.2.6 --- Compound C --- p.67 / Chapter 2.2.7 --- Incubation of Islets --- p.67 / Chapter 2.2.8 --- Western Blot --- p.68 / Chapter 2.2.9 --- Enzyme-Linked Immunosorbent Assay (ELISA) --- p.69 / Chapter 2.2.10 --- Statistical Analysis --- p.71 / Chapter CHAPTER 3 --- HISTOLOGY OF PORCINE PANCREATIC ISLETS OF LANGERHANS --- p.72 / Chapter 3.1 --- Comparison of Sizes of Porcine Pancreatic Islets in Histological Sections of Pancreas --- p.72 / Chapter CHAPTER 4 --- PROTEIN EXPRESSION OF HMG COA REDUCTASE --- p.75 / Chapter 4.1 --- Effect of Incubation Time on HMG CoA Reductase Expression --- p.75 / Chapter 4.2 --- Short-Term Effect of Simvastatin on HMG CoA Reductase Expression --- p.78 / Chapter 4.3 --- Long-Term Effect of Simvastatin on HMG CoA Reductase Expression --- p.81 / Chapter 4.4 --- Effect of Osmolality on HMG CoA Reductase Expression --- p.83 / Chapter 4.5 --- Effect of Simvastatin on Ser871 p-HMG CoA Reductase Expression --- p.87 / Chapter CHAPTER 5 --- EVALUATION OF THE ROLE OF SIMVASTATIN IN INSULIN SECRETION VIA HMG CO A REDUCTASE REGULATION --- p.90 / Chapter 5.1 --- Effect of Simvastatin on Insulin Secretion --- p.90 / Chapter 5.2 --- Effect of Different Concentrations of Simvastatin on Insulin Secretion --- p.94 / Chapter 5.3 --- Effect of Simvastatin on Insulin Content --- p.96 / Chapter CHAPTER 6 --- ROLE OF AMPK EXPRESSION IN INSULIN SECRETION PATHWAY --- p.100 / Chapter 6.1 --- Effect of Simvastatin on Thr172 p-AMPK α and AMPK α1 Expressions --- p.100 / Chapter 6.2 --- Evaluation of the Role of Simvastatin in AMPK Regulation --- p.104 / Chapter 6.3 --- Evaluation of the Role of PP2A in AMPK Regulation --- p.108 / Chapter 6.4 --- Evaluation of the Role of Simvastatin on Insulin Secretion via AMPK Regulation --- p.111 / Chapter 6.4.1 --- AMPK Regulation on Releasable Insulin Secretion --- p.111 / Chapter 6.4.2 --- AMPK Regulation on Non-Releasable Insulin Content and Total Insulin Content --- p.112 / Chapter CHAPTER 7 --- EFFECT OF SIMVASTATIN ON THE EXPRESSION OF REGULATORY PROTEINS INVOLVED IN INSULIN SECRETION --- p.119 / Chapter 7.1 --- Effect of Simvastatin on SREBP-2 Expression --- p.119 / Chapter 7.2 --- Effect of Simvastatin on Caveolin-1 Expression --- p.121 / Chapter 7.3 --- Effect of Simvastatin on Calcium Sensing Receptor Expression --- p.123 / Chapter CHAPTER 8 --- EFFECT OF SIMVASTATIN-NA+ ON INSULIN SECRETION --- p.126 / Chapter 8.1 --- Effect of Simvastatin-Na+ on HMG CoA Reductase Expression --- p.126 / Chapter 8.2 --- Effect of Simvastatin-Na+ on Insulin Secretion --- p.128 / Chapter 8.3 --- Effect of Different Concentrations of Simvastatin-Na+ on Insulin Secretion --- p.130 / Chapter 8.4 --- Effect of Simvastatin-Na+ on Insulin Content --- p.132 / Chapter CHAPTER 9 --- EFFECT OF PRAVASTATIN ON INSULIN SECRETION --- p.136 / Chapter 9.1 --- Effect of Pravastatin on Insulin Secretion --- p.136 / Chapter 9.2 --- Effect of Pravastatin on Insulin Content --- p.138 / Chapter CHAPTER 10 --- EFFECT OF METHYL-B-CYCLODEXTRIN ON INSULIN SECRETION --- p.142 / Chapter 10.1 --- Effect of Methyl-β-cyclodextrin on Insulin Secretion --- p.142 / Chapter 10.2 --- Effect of Methyl-β-cyclodextrin on Insulin Content --- p.144 / Chapter CHAPTER 11 --- DISCUSSION --- p.149 / Chapter 11.1 --- Importance of Studying Porcine Pancreatic Islets and Islet Distribution --- p.150 / Chapter 11.2 --- Screening of Concentration and Incubation Time of Simvastatin on Porcine Pancreatic Islets --- p.152 / Chapter 11.3 --- Glucose-Independent Effect of Simvastatin on Protein Expression of HMG CoA Reductase --- p.154 / Chapter 11.4 --- Role of AMPK in HMG CoA Reductase-Modulated Insulin Secretion --- p.159 / Chapter 11.5 --- Role of SREBP-2 in Simvastatin-Modulated Regulation --- p.174 / Chapter 11.6 --- Role of Calcium Sensing Receptor in Simvastatin-Modulated Regulation --- p.175 / Chapter 11.7 --- Role of Caveolin-1 in Simvastatin-Modulated Regulation --- p.179 / Chapter 11.8 --- "Effects of Simvastatin-Na+， Pravastatin and Methyl-β-cyclodextrin, and Importance of Endoplasmic Reticulum in Insulin Secretion" --- p.183 / Chapter CHAPTER 12 --- CONCLUSIONS AND FURTHER STUDIES --- p.197 / Chapter 12.1 --- Conclusions --- p.197 / Chapter 12.2 --- Further Studies --- p.203 / REFERENCES --- p.207

Statins are 3-hydroxy, 3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which block the cholesterol biosynthetic pathway to lower total serum levels and LDL-cholesterol. The cholesterol pathway also provides a supply of isoprenoids (farnesyl and geranylgeranyl) for the prenylation of signaling molecules, which include the families of Ras and Rho small GTPases. Prenyl groups provide a membrane anchor that is essential for the correct membrane localisation and function of these proteins. Statins deplete cells of lipid geranylgeranyl diphosphate (GGPP) thereby inhibiting progression of the mevalonate pathway and prenylation of proteins. Two such proteins are Rab27b and Rap1, small GTPase proteins that are involved in the secretion of platelet granule and integrin activation. We hypothesise that statins can impair prenylation of Rab27b and Rap1a in platelets and thereby attenuate platelet function. The specific aims of the project were to analyse the impact of statins on the prenylation status of Rab27b and Rap1a in platelets. As Rab27b and Rap1a are known to be involved in secretion of platelet granules a secondary aim was to analyse the downstream effects of statins on this process following activation. Finally, we assessed the impact of treatment of platelets with statins on thrombus formation, stability and resistance to fibrinolysis. Platelets incubated with statins overnight were separated into cytosolic (aqueous) and membrane (detergent) components and visualised by Western blot. An accumulation of Rab27b and Rap1a was observed in the cytosolic compartments of statins treated platelets compared to untreated platelets, thus indicating indirect evidence that statins attenuate prenylation of Rab27b and Rap1a in platelets. The most effective statin in attenuating prenylation of Rab27b and Rap1a was atorvastatin (ATV). The inhibitory effect of statins on prenylation was recovered by GGPP, indicating that the mechanism of inhibition involved the mevalonate pathway. Release of ADP from platelet dense granules was significantly impeded following overnight treatment with ATV. In line with the inhibition of prenylation of Rab27b and Rap1a by ATV, addition of GGPP rescued the release of ADP from platelet dense granules. This suggests that attenuation of dense granules release by ATV occurs via interference in the mevalonate pathway and the inhibition of Rab27b prenylation. Furthermore, ATV significantly attenuates α-granules release in thrombin stimulated platelets, which was visualised as impaired accumulation of endogenous P-selectin, PAI-1 and fibrinogen on the activated membrane. Changes in the activation of α₁₁bβ₃ integrin on the stimulated platelet surface, observed as defective binding of exogenous fibrinogen and PAC-1, were also evident following treatment of platelets with ATV. In addition, ATV treatment of platelets reduced binding of CD41a, indicating that the copy number and activation of α₁₁bβ₃ integrin on stimulated platelets was significantly reduced. Statins were also found to significantly inhibit thrombin-induced platelet aggregation following incubation of platelets overnight with therapeutic concentrations of statins. Surprisingly GGPP did not rescue platelet aggregation indicating that different mechanisms are involved in inhibition of platelet responses by statins. Incubation of whole blood with ATV overnight significantly altered several haemostatic parameters. Using thromboelastography we demonstrated a delay in the coagulation time and clot formation time. Maximum clot firmness was also significantly reduced in the presence of statins compared to the control. The effect on clot firmness generally arises from platelet dysfunction and/or a change in fibrinogen concentration and function; the latter was ruled out using a Fibtem test, which shows no difference between treated and untreated whole blood. Similarly, formation of platelet-rich plasma clots was significantly delayed following pre-treatment with ATV overnight. These clots also exhibited lower maximal absorbances, which could represent differences in the fibrin network structure. In line with the reduction in fibrinogen binding defective clot retraction was also observed in platelet-rich plasma pre-treated with ATV overnight. Similar clot retraction results were observed with tirofiban and CytoD, suggesting that the inhibitory effect of ATV may involve modulation of α₁₁bβ₃ integrin activation. Platelet-rich plasma clots formed post-treatment with statins were visualised by confocal microscopy and revealed significant alterations in clot structure; observed as thinner fibrin fibres and fewer platelet aggregates. Additionally, we demonstrated that statins modulate clot stability and shorten time to lysis. Clots formed from platelet rich plasma that was subjected to incubation with ATV overnight revealed faster lysis by tPA compared to the absence of statin. These findings are also in agreement with the lysis of Chandler model thrombi formed from overnight incubated whole blood with ATV, which demonstrated faster lysis rate mediated by tPA. Furthermore, statins were shown to change the clot thrombodynamics as assessed by HemaCore analyser, which shows that stains implicate both clot growth in response to TF-coated comb and spontaneous clot lysis by tPA. In conclusion, statins directly inhibit Rab27b and Rap1a prenylation in platelets and down-regulated dense granules release. Inhibition of Rab27b and Rap1a prenylation, and dense granules release was recovered by GGPP, indicating that these effects are mediated through the mevalonate pathway. Impairment of platelet aggregation by statins resulted via multiple mechanisms as GGPP did not recovered the inhibition of aggregation by ATV. Statins also modulate fibrinogen binding, α-granules release, clot retraction and clot formation and stability in vitro. Together these results suggest that statins may directly attenuate the platelet response in vivo. The pleotropic effect of statins on platelets may contribute to the protective function of these class of drugs in cardiovascular diseases.

As estatinas são substâncias que inibem a síntese de colesterol. Por não existir métodos analíticos simples e de baixo custo para determinação quantitativa de pravastatina sódica, fluvastatina sódica, atorvastatina cálcica e rosuvastatina cálcica, o objetivo desta pesquisa foi desenvolver, validar e comparar os métodos por cromatografia líquida de alta eficiência e espectrofotometria direta e derivada no ultravioleta para a determinação quantitativa de estatinas em comprimidos. Os métodos cromatográficos foram realizados em coluna LiChrospher® RP-18 com fase móvel composta de metanol-água e pH ajustado a 3,0 com ácido fosfórico. Os métodos espectrofotométricos foram validados utilizando NaOH 0,1 M como solvente. A análise estatística com os testes t e F, não mostraram diferença significativa entre os métodos propostos ao nível de confiança de 95%. Os métodos são simples, eficientes e podem ser utilizados em análises de rotina para o controle de qualidade de estatinas em comprimidos. / The statins are substances that inhibit the synthesis of cholesterol. There is no simple and low cost analytical methods for quantitative determination of pravastatin sodium, fluvastatin sodium, atorvastatin calcium and rosuvastatin calcium; the objective of this research was to develop, to validate and to compare the methods as high performance liquid chromatography and ultraviolet direct and derivative spectrophotometry for quantitative determination of statins in tablets. The chromatographic methods were carried out with a LiChrospherB RP-18 column with a mobile phase composed of methanol-water and pH adjusted to 3.0 with phosphoric acid. The spectrophotometric methods were validated using NaOH 0.1 M as solvent. The statistical analysis using tests t and F, did not show significant difference between the methods considering the 95% confidence level. The methods are simple, efficient and can be used in routine analyses for quality control of statins in tablets.

Background: There are approximately 12 million statin users in the United Kingdom. Reports of statin intolerance occurs between 7 and 29% of users, manifesting as muscle ache, fatigue or more seriously, muscle breakdown leading to myopathy. Creatine phosphokinase (CK) levels are used as a biomarker of statin-induced muscle damage. Non-adherence or discontinuation of therapy is a common result of intolerance and can result in negative cardiovascular disease-related outcomes. Aim: This thesis attempts to identify trends in record-linked medical data in a Scottish Caucasian cohort (GoDARTS) that best represent statin intolerance in order to study associated genetic factors. Methods: Prescribing trends such as switching or discontinuation of statin therapy were examined, and thresholds created to select true cases of intolerance. Information on CK levels was gathered from medical records and appropriate test results were utilized. Genotypic data was gathered for the variants and genetic regions of interest using a variety of methods including chip-based genotyping followed by imputation, TAQMAN genotyping, and exome sequencing. Subsequently hypothesis-based association analyses were conducted, including linear and logistic regressions, followed by meta-analyses, regional GWAS followed by a regional meta –analysis. Results: The phenotypes of statin intolerance were validated both internally and externally. Previously reported missense variants in LILRB5 (Asp247Gly) and CKM (Glu83Gly) were replicated and shown to be associated with CK levels irrespective of statin usage in the GoDARTS cohort and the clinical trial setting (JUPITER). Further, the CKM variant was also associated with inducibility of CK at times of tissue injury. The Asp247 genotype in LILRB5 was associated with increased risk of statin intolerance, and was replicated in associations with non-compliance to statin therapy and the development of myalgia in the JUPITER trial. The association with myalgia showed a stratified effect based on therapy (statin or placebo), with those on placebo showing the genotype effect. Further, the variant was also associated with increased risk of statin-induced myositis, cases of which had been clinically adjudicated and exome sequenced for the PREDICTION-ADR consortium. Further exploration of the LILR gene region showed an association with variants in LILRB2 (His20Arg and Val235Met) which were in strong LD with each other but were not in linkage with the variant in LILRB5. Stratified analysis revealed that the risk for carriers of the LILRB2 variants was increased depending on the genotype carried at the LILRB5 variant. Conclusions: This study characterises novel genetic factors associated with statin intolerance impacting adherence. The findings point to the immunomodulatory effects of statins. The results suggest that true statin-induced myalgia and non-specific myalgia are distinct, with a possible role for the immune system in their development. The findings encourage further investigation into the immune-physiology of statin-induced muscle damage and identifies genetically susceptible groups who are more likely to be statin intolerant.

Statins are cholesterol-lowering medications with immunologic properties. To assess the role of statins on incident immune-mediated conditions, a modified case-cohort study was performed using administrative databases from the Midwest Veterans Administration (VA) region. A comparison sub-cohort was formed by randomly sampling 10,000 subjects with medical and pharmacy benefits during fiscal year (FY) 2002. Cases were identified by inpatient or outpatient medical claims using International Classification of Disease, Ninth Revision (ICD-9) codes between FY 2003-2004. All subjects needed at least one year of medical claims and at least one pharmacy claim. The incident cases (n=28,642) included non-mutually exclusive groups of immune-mediated (n=2,327), infectious (n=8,221), and non-immunologic (n=10,730) diagnoses. Demographic and medical variables were obtained from FY 2001-2004, and pharmacologic data from FY 2002-2004. Cox proportional hazards regression modeling was used to estimate hazard ratios for the current statin use (within the last 180 days) and former statin use, compared to non-users, including time-dependant variables for demographic factors, comorbidity as measured by Elixhauser and Chronic Disease Score variables, medications, and visit rates after initiating statins. Current statin use was associated with decreased diagnoses rates of psoriasis; rheumatoid arthritis; inflammatory bowel diseases, including ulcerative colitis and Crohn disease; diffuse connective tissue diseases, including systemic lupus erythematosus; ankylosing spondylitis; bacterial pneumonia; urinary tract infection; cellulitis; sepsis; candidiasis; osteomyelitis; and tuberculosis. Former statin use was also associated with increased rates of polymyalgia rheumatica, sepsis, and osteomyelitis. Statin use was not associated with other spondylitis, multiple sclerosis, thyroiditis, sarcoidosis, temporal arteritis, influenza, shingles, histoplasmosis, or pyelonephritis. Although current statin use appeared protective for some study conditions, selection bias, misclassification, healthy user effects, adherence bias, confounding by indication, and surveillance bias were considered as possible explanations of the study findings.

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are unequivocally useful for lowering cholesterol levels in patients with dyslipidemias. In addition to cholesterol lowering properties, statins exert a number of pleiotropic, vascular-protective effects include improvement of endothelial function, increased nitric oxide (NO) bioavailability, antioxidant properties. Since endothelial dysfunction and reactive oxygen species (ROS) are important pathophysiological determinants of essential hypertension, these actions of statins raise the possibility that statin therapy may be useful for simultaneously clinical hypertension management. However, the signaling mechanisms of statins that improve hypertension remain unclear. Our previous study showed, in the NTS, insulin may decrease blood pressure and heart rates through PI3K-Akt-eNOS pathway, and NTS integrates convergent information from peripheral baroreceptors and central cardiovascular regulatory center. Statins also prevent the synthesis of other important isoprenoid intermediates of the cholesterol biosynthetic pathway, members of the Ras and Rac1 GTPase family are major substrates for posttranslational modification by isoprenylation and may be important targets for inhibition by statins. Statins could inhibit Rac1 isoprenylation and Rac1-mediated nicotinamide adenine dinucleotide phosphate oxidase activity attenuates reactive oxygen species production. The aim of this study was to investigate the possible signaling pathways involved in simvastatin-mediated blood pressure regulation in the nucleus tractus solitarii (NTS). Male 20-week-old spontaneously hypertensive rats (SHR) were divided into two groups: control group and intracerebroventricular injection with simvastatin group for three days. We found that systolic blood pressure measured with tail-cuff method of the simvastatin-treated rats decreased significantly, and the NO level in the NTS was significantly increased. In addition, we observed that simvastatin could lower the ROS level and increase Ras GTPase activity in the NTS. Immunoblotting and immunohistochemistry analysis further showed that simvastatin increased the phosphorylation ratio of ERK1/2, Akt, and endothelial nitric oxide synthase (eNOS) in the NTS. Taken together, these results suggest that eNOS signaling in the NTS may play an important role in simvastatin-induced blood pressure lowering effects. Keywords: statins, nucleus tractus solitarii, nitric oxide, oxidative stress, central cardiovascular regulatory, isoprenylation

Background Cardiovascular disease (CVD) is the worldwide leading cause of death among non-communicable diseases and results in a huge burden of mortality and morbidity. China, a rapidly growing East Asian country, has the world largest population and is facing an increasing burden. Incidence of CVD is lower in China than in Western countries. There are more strokes, especially hemorrhagic strokes, but less coronary heart disease (CHD) in China than in Western countries. Statin, a first-choice drug for lowering low-density lipoprotein cholesterol (LDL-C), has been shown to be effective in preventing CVD and is widely used in Western countries. However, it is not known whether the same can be applied to Asian countries, where the incidence of CVD is lower and ischemic events are rarer. The aim of this systematic review is to evaluate the effectiveness of statin for prevention of CVD in East Asian populations. Methods A systematic review was conducted by searching for randomized controlled trials from 3 databases (PubMed, MEDLINE and Cochrane Trial) for prevention of CVD comparing statin with usual care or placebo in East Asian population. Data on CVD events (deaths, CHD and cerebrovascular events, rehospitalization and revascularization) and serum lipid levels (total cholesterol (TC), LDL-C, high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG)) were extracted. Risk ratios of CVD events and change in serum lipid level were tabulated. The relationship between change in serum lipid level and mortality and incidence of CVD events were also explored. Results Fourteen studies were included, with most of them (9 studies) done in Japan. Overall, statins did not significantly reduce risk of mortality, CHD events, cerebrovascular events, revascularization and rehospitalization due to CHD. However, statins consistently lowered the risk of angina-related rehospitalization by 53% (95% confidence interval (CI) 23% to 71%) and 64% (95% CI 11% to 86%) respectively in 2 studies. There was a consistent reduced risk of composite CVD events by 34% (95% CI 5% to 55%) to 54% (95% CI 6% to 41%) in 4 studies for secondary prevention. In terms of change in lipid levels, TC and LDL-C were significantly reduced by 8% to 31% and 14% to 41% respectively with statin treatment. Change in HDL-C and TG were not consistent across studies. Lowering of TC and LDL-C level was correlated with the reduction in composite CVD and CHD events. Conclusion The use of statins in East Asian populations to prevent CVD may not be as effective as in Western countries, because of the lower baseline risk and different patterns of CVD. As the prevalence of CVD risk factors increases, the incidence of CVD will increase and the pattern of CVD may change, so careful monitoring is needed. More importantly, most of the studies included had small sample sizes, short follow-up periods and/or low methodological quality, which might contribute to the inconsistent findings. A further large-scale randomized controlled trial should be done to confirm the benefits of statins among Chinese. / published_or_final_version / Public Health / Master / Master of Public Health

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