No description available.

Class of 2006 Abstract / Objectives: To evaluate the efficacy of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, in reducing all-cause mortality and death due to rejection when administered to thoracic organ transplant patients. Methods: Using the following Medical Subject Heading (MeSH) terms and text words: hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, heart transplantation, and lung transplantation, the following data bases were searched: Cochrane Central Register of Controlled Trials (First Quarter 2006), Cochrane Database of Systematic Reviews (First Quarter 2006), Database of Abstracts and Reviews of Effects (First Quarter 2006), ACP Journal Club (1991to January/February 2006), International Pharmaceutical Abstracts (1970-February 2006), and Medline (1966 to February 2006) for English language reports. Three prospective randomized controlled trials (RCTs) and 3 retrospective observational studies were identified as using statins to reduce mortality and death due to fatal rejection in thoracic organ transplant patients. Results: Using all 6 studies (n= 1770 patients), statins decreased mortality by 77% (OR=0.23; [95% confidence interval 0.16-0.34] Z test, P<0.001). Sub-analysis using only RCT heart transplant data showed that statins decreased mortality by 69% (OR=0.31; [95% confidence interval 0.09-1.07] Z test, P<0.003). Sub-analysis using retrospective heart transplant data showed that statins decreased mortality by 75% (OR=0.25; [95% confidence interval 0.16-0.39] Z test, P<0.001). Retrospective lung transplant results (1 study) showed statins decreased mortality by 90% (OR=0.10; [95% confidence interval 0.03-0.34] Z test, P<0.001). Statins also significantly reduced death due to rejection (OR=0.22; [95% confidence interval 0.13-0.37]). Using all 6 studies (n= 1770 patients), statins decreased death due to rejection by 78%. Conclusions: In patients undergoing thoracic organ transplantation, statins significantly decrease all-cause mortality and death due to rejection. Therefore, statins should be routinely administered to these patients following transplant surgery.

Loss-of-function genetic screens are a powerful approach to identify the genes involved in biological processes. For nearly a century, forward genetic screens in model organisms have provided enormous insight into many cellular processes. However, the difficulty in generating and recovering bi-allelic mutations in diploid cells severely hindered the performance of forward genetic screens in mammalian cells. The development of a retroviral gene-trap vector to mutagenise the human near-haploid KBM7 cell line transformed forward genetic screens in human cells. The re-purposing of the microbial CRISPR/Cas9 system now offers an effective method to generate gene knockouts in diploid cells. Here, I performed a head-to-head comparison of retroviral gene-trap mutagenesis screens and genome-wide CRISPR knockout screens in KBM7 cells. The two screening approaches were equally effective at identifying genes required for the endoplasmic reticulum (ER)-associated degradation of MHC class I molecules. The ER-resident enzyme HMG-CoA reductase (HMGCR) catalyses the rate-limiting step in the cholesterol biosynthesis pathway and is targeted therapeutically by statins. To maintain cholesterol homeostasis, the expression of HMGCR is tightly regulated by sterols transcriptionally and post-translationally. Sterols induce the association of HMGCR with Insig proteins, which recruit E3 ubiquitin ligase complexes to mediate degradation of HMGCR by the ubiquitin proteasome system. However, the identity of the E3 ligase(s) responsible for HMGCR ubiquitination is controversial. Here, I use a series of genome-wide CRISPR knockout screens using a fluorescently-tagged HMGCR exogenous reporter and an endogenous HMGCR knock-in as an unbiased approach to identify the E3 ligases and any additional components required for HMGCR degradation. The CRISPR screens identified a role for the poorly characterised ERAD E3 ligase RNF145. I found RNF145 to be functionally redundant with gp78, an E3 ligase previously implicated in HMGCR degradation, and the loss of both E3 ligases was required to significantly inhibit the sterol-induced degradation and ubiquitination of HMGCR. A focused E3 ligase CRISPR screen revealed that the combined loss of gp78, RNF145 and Hrd1 was required to completely block the sterol-induced degradation of HMGCR. I present a model to account for this apparent complexity.

No description available.

Class of 2012 Abstract / Specific Aims: To evaluate the quality of evidence in the literature substantiating major drug-drug interactions of the HMG-CoA reductase inhibitors (statins) atorvastatin, lovastatin, and simvastatin with the azole anti-fungals fluconazole, itraconazole, and ketoconazole. Methods: In this descriptive retrospective analysis, a list of articles reporting on each drug-drug interaction was compiled from the online databases Medline and International Pharmaceutical Abstracts, and the drug compendia Micromedex and Facts & Comparisons. The studies included in this analysis were primary literature reports, written in English, and consisted of human subjects. All studies included were evaluated using a 5-point quality of evidence scale developed to assess drug-drug interactions (van Roon scale). This scale rates the study type from lowest to highest quality, from zero to four. Case reports were additionally analyzed using the Drug Interaction Probability Scale (DIPS). The DIPS tool uses 10 questions to evaluate the probability that an adverse event is caused by a drug-drug interaction. Main Results: Twenty-one studies met the selection criteria. There were three studies involving atorvastatin, four studies involving lovastatin, and fourteen studies involving simvastatin. The mean quality of evidence score on the van Roon scale was 2.0 + 0.77, where atorvastatin studies had a score of 2.3 + 1.15, lovastatin had a score of 2.25 + 0.95 and simvastatin had a score of 1.86 + 0.66. Seventy-one percent of the studies reviewed were case reports. Conclusions: The reports substantiating some drug-drug interactions may be of little and low quality evidence.

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.

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.

The temperature-dependent catalytic activity of rat liver 3-hydroxy-3 -methylglutaryl coenzyme A reductase (HMG-CoA reductase) displays the nonlinear Arrhenius behavior characteristic of many membrane-bound enzymes. A two-conformer equilibrium model has been developed to characterize this behavior. In the model, HMG-CoA reductase undergoes a conformational change from a low specific activity to a high specific activity form. This conformation change is apparently driven by a temperature-dependent phase transition of the membrane lipids. It has been found that this model accurately describes the data from diets including rat chow, low-fat, high-carbohydrate, and diets supplemented with fat, cholesterol or cholestyramine. The effects characterized by the model are consistent with the regulation of HMG-CoA reductase by enzyme-lipid interactions.

There is conflicting data on the effects of statins on cerebral vasospasm and clinical outcomes in aneurysmal subarachnoid hemorrhage (aSAH) patients. In this retrospective cohort study, patients were divided into those who received pravastatin (PRAV group) 40mg/d and those who did not (NP group). Data were analyzed using multivariate logistic regression. Eighty-one patients met inclusion criteria. There was a statistically significant decreased in the incidence of vasospasm in the PRAV group; however, this association did not retain significance after adjusting for WFNS, race, elevated WBC, and clipping (59% PRAV vs. 88% NP, p=0.08). There was no statistically significant difference in proportion of severe radiological vasospasm or mortality between groups. However, there was a trend towards a decreased mean length of stay (P=0.06) and a significantly higher proportion of survivors discharged to home in the PRAV group (P<0.0001). In conclusion, there was a trend towards a decrease in the incidence of vasospasm in the aSAH receiving pravastatin, but this trend did not achieve statistical significance after adjusting for potential confounders. Pravastatin was associated with other favorable clinical outcomes.

Selenium (Se) is an essential mineral with functions for both animals and humans. There are several regions in the world deficient in this mineral and studies have related Se supplemented with reducing cholesterol. Thus, the objective of this study was to evaluate the Se effect in different levels and sources in the diet finishing of Nellore cattle on the performance and meat quality. It was used 63 Nellore cattle (412 kg and &plusmn; 24 months of age) in a completely randomized design with two sources (sodium selenite and selenium-enriched yeast) and four supplementation levels (0; 0.3; 0.9 and 2.7 mg Se/kg DM). There were no changes in performance and carcass characteristics. The Se level reduced (P&lt;0.01) lipid and proteins oxidation (TBARS and carbonyl) compared to the control treatment on retail display storage (0, 2, 4 and 6 days). Organic Se, regardless of level, provided Se 138% higher (P&lt;0.0001) in meat and 22.6% higher (P&lt;0.0001) in serum than inorganic Se. The activity of glutathione peroxides (GPx) in muscle was 288% higher for animals supplemented with selenium and consequently, the cholesterol concentration in L. dorsi was 10.2% lower (P&lt;0.001). The serum HMG-CoA reductase concentration was 32.7% lower in animals receiving Se supplementation (organic or inorganic). In conclusion, Se supplementation in beef cattle diet is a way of naturally producing selenium-enriched meat and with better quality for human consumption. / O selênio (Se) é um mineral essencial com funções para animais e humanos. Existem várias regiões do mundo deficientes neste mineral e estudos têm relacionado a suplementação de Se com a redução do colesterol. Assim, o objetivo deste estudo foi avaliar o efeito de diferentes teores e fontes de Se na dieta de terminação de bovinos Nelore sobre o desempenho e a qualidade da carne. Foram utilizados 63 animais da raça Nelore (412 kg e &plusmn; 24 meses de idade) em delineamento inteiramente casualizado, com duas fontes (selenito de sódio e selênio levedura) e quatro teores de suplementação (0; 0,3; 0,9 e 2,7 mg Se/kg MS) em confinamento, durante 84 dias. Não houve alterações no desempenho e nas características de carcaça. O teor de Se reduziu (P &lt;0,01) a oxidação lipídica e proteica (TBARS e carbonila) em comparação ao tratamento controle durante o armazenamento em simulação de exposição no varejo (0, 2, 4 e 6 dias). O Se orgânico, independentemente do teor, forneceu valor de Se 138% superior (P &lt;0,0001) na carne e 22,6% superior (P &lt;0,0001) no soro em relação ao Se inorgânico. A atividade glutationa peroxidase (GPx) no músculo foi 288% maior nos animais suplementados com selênio e, consequentemente, a concentração de colesterol na carne foi 10,2% menor (P &lt;0,001). A concentração sérica de HMG-CoA redutase foi 32,7% menor nos animais que receberam suplementação de Se (orgânico ou inorgânico). Foi concluído que a suplementação com Se na dieta de bovinos de corte é uma forma de produzir carnes enriquecidas com selênio naturalmente e com melhor qualidade para consumo humano.