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Four samples of cellulose acetates having degrees of combined acetic acid between 50.8 - 55.8% were fractionated to obtain sharp fractions or approximately the same degree of polymerization. About 2000 grams starting material of each sample of cellulose acetate were needed to obtain approximately 50 grams or sharp fraction for testing the mechanical properties of their films. Fractionation of the cellulose acetate was from an acetone-water mixture, by addition of n-heptane to precipitate a certain traction. After a series of refractionations, a sharp fraction of each of the four cellulose acetates was obtained. These fractions had different degrees of acetylation but approximately the same degrees of polymerization. These fractions were then dissolved in acetone and cast into films which were conditioned for three days and their mechanical properties were determined in an attempt to determine the effect of degree of acetylation on the mechanical properties. It was found that the degrees of acetylation of the various sharp tractions of cellulose acetates had no appreciable effect on the mechanical properties of their films. It was concluded that the degrees of polymerization of the various fractions were so high that the effect of the degree or acetylation on the mechanical properties could not be detected. The degrees of polymerization of the various samples were determined by the viscosity method using acetone and cupriethylenediamine as the solvents, It was found that the degrees of polymerization of the various samples of cellulose acetates determined by the cupriethylenediamine viscosity method were almost four times greater than the degrees of polymerization of the same samples determined by the acetone viscosity method using constants obtained from the literature. / Ph. D.

The most common cause of death is cardiovascular disease, with a prevalence of 3,500 per 100,000 people worldwide (Pirani and Khiavi 2017). Tissue ischemia due to cardiovascular diseases induces disorder such as myocardial infarction, pulmonary arterial hypertension, and atherosclerosis. In ischemic cardiomyopathy, heart failure is caused by the cardiac muscle getting damaged due to ischemia and losing its ability to pump blood properly. These ischemic conditions can affect cellular homeostasis and metabolism, which can result in cardiovascular dysfunction. Considering the effect of ischemic cardiomyopathy on the global population, it is vital to understand the impact of ischemia on the cardiac cells and how ischemic condition changes different cellular functions through epigenetic changes. Epigenetics has been associated with some cardiovascular disease risk factors, so reversing or modifying these changes through drug therapy could reverse or prevent the effects of CVD. A combination of genetics and environmental factors can regulate gene expression dynamically on a physiological level. Additionally, post-translational modifications (PTM) play an important role in cellular gene expression through epigenetic changes. Neonatal rat primary cardiomyocytes were used to understand the changes in acetylation during ischemic conditions compared to normoxic conditions. Mass spectrometry was performed on proteins isolated from these samples to analyze changes in acetylation due to ischemia. Analysis was performed to link genomic information with higher-order functional information for the identified proteins. These acetylated changes were found to be localized in different subcellular organelles and involved various molecular functions and biological processes. This study aims to identify global acetylation changes in cells exposed to ischemic conditions to identify therapeutic targets to prevent and treat ischemia-mediated heart disease.

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Yes / The NAD(+)-dependent deacetylase SIRT1 is involved in diverse cellular processes, and has also been linked with multiple disease states. Among these, SIRT1 expression negatively correlates with cancer survival in both laboratory and clinical studies. Active regulator of SIRT1 (AROS) was the first reported post-transcriptional regulator of SIRT1 activity, enhancing SIRT1-mediated deacetylation and downregulation of the SIRT1 target p53. However, little is known regarding the role of AROS in regulation of SIRT1 during disease. Here, we report the cellular and molecular effects of RNAi-mediated AROS suppression, comparing this with the role of SIRT1 in a panel of human cell lines of both cancerous and non-cancerous origins. Unexpectedly, AROS is found to vary in its modulation of p53 acetylation according to cell context. AROS suppresses p53 acetylation only following the application of cell damaging stress, whereas SIRT1 suppresses p53 under all conditions analysed. This supplements the original characterization of AROS but indicates that SIRT1 activity can persist following suppression of AROS. We also demonstrate that knockdown of AROS induces apoptosis in three cancer cell lines, independent of p53 activation. Importantly, AROS is not required for the viability of three non-cancer cell lines indicating a putative role for AROS in specifically promoting cancer cell survival.