No description available.

No description available.

Myocardial infarction (MI) is a leading cause of congestive heart failure (CHF), and its course of cardiac remodeling is of paramount importance in prevention and treatment of cardiac dysfunction. Activation of the sympathetic nervous system (SNS), and the renin angiotensin system (RAS), is critical in cardiac subcellular remodeling post MI. Although blockade has prevented remodeling, little is known regarding the beneficial effects in reversing subcelllular changes in failing hearts. Upon rat coronary artery occlusion - losartan, metoprolol, and prazosin were initiated 12 weeks post MI for 8 weeks, to evaluate their reversal effects at the molecular and cellular levels. As the sarcoplasmic reticulum (SR) primary regulates intracellular Ca2+ in cardiac contraction/relaxation, we hypothesized that abnormalities in its function and regulation contribute to contractile dysfunction. We examined cardiac performance, SR function, SR molecular expression and plasma catecholamine levels 20 weeks post MI. The fibrinous myocardium, cardiac hypertrophy and pulmonary edema all portrayed CHF, in addition to elevated LVEDP and depressed dP/dt. Ejection fraction, fractional shortening, and cardiac output were all significantly reduced, as were IVSs, LVIDd, LVPWs, and LVPWd. SR preparations showed altered phospholamban (PLB) and sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) mRNA, which appropriately matched their protein expression. These modifications correlated to decreased cardiac SR Ca2+-uptake, providing further disruptions in Ca2+ homeostasis. Therefore, these modifications in the mRNA of PLB and SERCA2a are postulated to play a critical role in SR protein remodeling. Supplementary studies addressed remodeling of mRNA myofibrils, which revealed a decreased α-MHC isozyme with an increased β-MHC isozyme, and reduced myofibrillar Ca2+-stimulated ATPase post MI. Finally, circulating plasma catecholamine levels of norepinephrine, epinephrine and dopamine were significantly elevated. Losartan, metoprolol, and prazosin corrected lung edema, myocardial hypertrophy, cardiac contractile dysfunction, and attenuated PLB and SERCA2a proteins, whereas α- and β- MHC mRNA were only attenuated by losartan; and metoprolol only attenuated β-MHC mRNA. SR Ca2+-uptake activities and plasma catecholamines of norepinephrine were partially reversed, yet dopamine was only affected by losartan. Early work previously focused on prevention, but this study is one of the first to attempt reversal of cardiac subcellular remodeling in CHF due to MI.

Myocardial infarction (MI) is a leading cause of congestive heart failure (CHF), and its course of cardiac remodeling is of paramount importance in prevention and treatment of cardiac dysfunction. Activation of the sympathetic nervous system (SNS), and the renin angiotensin system (RAS), is critical in cardiac subcellular remodeling post MI. Although blockade has prevented remodeling, little is known regarding the beneficial effects in reversing subcelllular changes in failing hearts. Upon rat coronary artery occlusion - losartan, metoprolol, and prazosin were initiated 12 weeks post MI for 8 weeks, to evaluate their reversal effects at the molecular and cellular levels. As the sarcoplasmic reticulum (SR) primary regulates intracellular Ca2+ in cardiac contraction/relaxation, we hypothesized that abnormalities in its function and regulation contribute to contractile dysfunction. We examined cardiac performance, SR function, SR molecular expression and plasma catecholamine levels 20 weeks post MI. The fibrinous myocardium, cardiac hypertrophy and pulmonary edema all portrayed CHF, in addition to elevated LVEDP and depressed dP/dt. Ejection fraction, fractional shortening, and cardiac output were all significantly reduced, as were IVSs, LVIDd, LVPWs, and LVPWd. SR preparations showed altered phospholamban (PLB) and sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) mRNA, which appropriately matched their protein expression. These modifications correlated to decreased cardiac SR Ca2+-uptake, providing further disruptions in Ca2+ homeostasis. Therefore, these modifications in the mRNA of PLB and SERCA2a are postulated to play a critical role in SR protein remodeling. Supplementary studies addressed remodeling of mRNA myofibrils, which revealed a decreased α-MHC isozyme with an increased β-MHC isozyme, and reduced myofibrillar Ca2+-stimulated ATPase post MI. Finally, circulating plasma catecholamine levels of norepinephrine, epinephrine and dopamine were significantly elevated. Losartan, metoprolol, and prazosin corrected lung edema, myocardial hypertrophy, cardiac contractile dysfunction, and attenuated PLB and SERCA2a proteins, whereas α- and β- MHC mRNA were only attenuated by losartan; and metoprolol only attenuated β-MHC mRNA. SR Ca2+-uptake activities and plasma catecholamines of norepinephrine were partially reversed, yet dopamine was only affected by losartan. Early work previously focused on prevention, but this study is one of the first to attempt reversal of cardiac subcellular remodeling in CHF due to MI.

DISC1, a strong genetic candidate for psychiatric illness, is a molecular scaffold residing in multiple subcellular compartments, where it regulates the function of interacting proteins with key roles in neurodevelopment and plasticity. Both common and rare DISC1 missense variants are associated with risk of mental illness and/or brain abnormalities in healthy carriers, but the underlying mechanisms are unclear. In this thesis, I initially examine the effect of a panel of common and rare single amino acid substitutions on DISC1 subcellular targeting, establishing that the rare mutation R37W and the common variant L607F disrupt DISC1 nuclear targeting in a dominant-negative fashion. This finding predicts that DISC1 nuclear expression is severely impaired in 37W and 607F carriers. In addition, I show that the L607F substitution results in aberrant cytoplasmic and cytoskeletal distribution of DISC1. In the nucleus, DISC1 interacts with the transcription factor ATF4, which is involved in the regulation of cellular stress responses and memory consolidation. Here I show that at basal cAMP levels, wild-type DISC1 strongly inhibits the transcriptional activity of ATF4, and this effect is ablated by 37W and 607F, most likely as a consequence of their defective nuclear targeting. 607F additionally reduces DISC1/ATF4 interaction, which likely contributes to its weakened inhibitory effect. I also demonstrate that DISC1 modulates transcriptional responses to endoplasmic reticulum stress, and that this modulatory effect is also ablated by 37W and 607F. By providing evidence that single amino acid substitutions of DISC1 associated with psychiatric illness impair its regulatory function on ATF4-dependent transcription, I highlight a potential mechanism by which these protein variants may impact on molecular pathways underlying cognition and stress responses, two processes of direct relevance to psychiatric disease.

No description available.

Proteins play many roles in the body, and the task of understanding how proteins function is very challenging. Determining a protein’s location within the cell (also referred to as the subcellular location) helps shed light on the function of that protein. Protein subcellular location can be inferred through experimental methods or predicted using computational systems. In particular, we focus on two existing computational systems, namely EpiLoc and HomoLoc, that use features derived from text (abstracts of technical papers), and apply a support vector machine (SVM) classifier to classify proteins into their respective locations. Both EpiLoc and HomoLoc’s prediction accuracy is comparable to that of state-of-the-art protein location prediction systems. However, in addition to accuracy, other factors such as training efficiency must be considered in evaluating the quality of a location prediction system. In this thesis, we replace the SVM classifier in EpiLoc and HomoLoc, by a naïve Bayes classifier and by a novel classifier which we call the Mean Weight Text classifier. The Mean Weight Text classifier and the naïve Bayes classifier are simple to implement and execute efficiently. In addition, naïve Bayes classifiers have been shown effective in the context of protein location prediction and are considered preferable to SVM due to clarity in explaining the process used to derive the results. Evaluating the performance of these classifiers on existing data sets, we find that SVM classifiers have a slightly higher accuracy than naïve Bayes and Mean Weight Text classifiers. This slight advantage is offset by the simplicity and efficiency offered by naïve Bayes and Mean Weight Text classifiers. Moreover, we find that the Mean Weight Text classifier has a slightly higher accuracy than the naïve Bayes classifier. / Thesis (Master, Computing) -- Queen's University, 2010-07-06 11:06:47.613

Thesis (Ph.D.). / Written for the Division of Experimental Medicine. Title from title page of PDF (viewed 2008/05/09). Includes bibliographical references.

No description available.

Schistosomiasis is one of the most widespread parasite diseases in the world, whereas Schistosoma mansoni is a major schistosome species in Africa, America, and the Caribbean islets. Many antigenic vaccine candidates have been postulated, including sm22.6 and GST. Although the lower level of re-infection of human schistosomiasis is related to the higher level of IgE against rsm22.6, unfortunately, the observation of the experimental vaccination in mice finds some difficulties in further development of vaccine. In addition, the biochemical and biophysical properties of the antigen are virtually unknown, thus the present study intends to characterize sm22.6 from biochemistry and cell biology. To do this, sm22.6 was expressed in E. coli (BL21DE3) and purified to homogeneity. Analyses of the recombinant protein showed that the antigen was highly hydrophobic and formed polymers readily as judged by both native and denatured electrophoreses. Because various technologies including NMR and DNA binding which had been applied to the study of the antigen generated vague results, we decided to express the antigen in human breast cancer cell (MDA-MB-435s) to locate in the subcellular compartments where the antigen is situated. Results showed that the antigen, not like the recombinant expressed in E. coli, located in both cellular fluids and membrane, suggesting that the antigen might not be a skeleton protein as predicted by proteomics.