Browsing by Issue Date, starting with "2020-03-03"
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- Impact of public health initiatives on acute coronary syndrome fatality rates in PortugalPublication . Abreu, Daisy; Sousa, Paulo; Matias Dias, Carlos; Pinto, FaustoIntroduction and objective: Every year cardiovascular disease (CVD) causes 3.9 million deaths in Europe. Portugal has implemented a set of public health policies to tackle CVD mortality: a smoking ban in 2008, a salt reduction regulation in 2010 and the coronary fast-track system (FTS) for acute coronary syndrome (ACS) in 2007. Our goal in this study was to analyze the impact of these three public health policies in reducing case-fatality rates from ACS between 2000 and 2016. Methods: The impact of these policies on monthly ACS case-fatalities was assessed by creating individual models for each of the initiatives and implementing multiple linear regression analysis, using standard methods for interrupted time series. We also implemented segmented regression analysis to test which year showed a significant difference in the case-fatality slopes. Results: Separate modeling showed that the smoking ban (beta=-0.861, p=0.050) and the FTS (beta=-1.27, p=0.003) had an immediate impact after implementation, but did not have a significant impact on ACS trends. The salt reduction regulation did not have a significant impact. For the segmented model, we found significant differences between case-fatality trends before and after 2009, with rates before 2009 showing a steeper decrease. Conclusions: The smoking ban and the FTS led to an immediate decrease in case-fatality rates; however, after 2009 no major decrease in case-fatality trends was found. Coronary heart disease constitutes an immense public health problem and it remains essential for decision-makers, public health authorities and the cardiology community to keep working to reduce ACS mortality rates.
- Metabolic tumor cell adaptation: tyrosine phosphorylation modulates cell surface expression of NKCC2 and KCC3Publication . Loureiro, Cláudia; Barros, Patrícia; Matos, Paulo; Jordan, PeterIntroduction: Tumor cells require cellular chloride and potassium transport to adapt to a changing microenvironment, both for cell volume regulation and membrane potential maintenance. Cellular chloride and potassium entry or exit are mediated at the plasma membrane by cotransporter proteins of the solute carrier 12 family. For example, NKCC2 resorbs chloride with sodium and potassium ions at the apical membrane of epithelial cells in the kidney, whereas KCC3 releases chloride with potassium ions at the basolateral membrane. Their ion transport activity is regulated by protein phosphorylation in response to signaling pathways. An additional regulatory mechanism concerns the amount of cotransporter molecules inserted into the plasma membrane. Material and Methods: Cotransporter constructs were transfected into HEK293 cells and the activity of spleen tyrosine kinase (SYK) modulated by incubation with SYK inhibitors or by co-transfection with siRNAs, kinase-dead, or constitutively active SYK mutants. Cotransporter abundance in the plasma membrane was analyzed by biotinylation of cell surface proteins. Results and Discussions: Here we describe that tyrosine phosphorylation of NKCC2 and KCC3 regulates their plasma membrane expression levels. We identified that SYK phosphorylates a specific N-terminal tyrosine residue in each cotransporter. Experimental depletion of endogenous SYK or pharmacological inhibition of its kinase activity increased the abundance of NKCC2 at the plasma membrane of human embryonic kidney cells. In contrast, overexpression of a constitutively active SYK mutant decreased NKCC2 membrane abundance. Intriguingly, the same experimental approaches revealed the opposite effect on KCC3 abundance at the plasma membrane, compatible with the known antagonistic roles of NKCC and KCC cotransporters in cell volume regulation. Conclusion: We identified a novel pathway modulating the cell surface expression of NKCC2 and KCC3 and show that this same pathway has opposite functional outcomes for these two cotransporters. The findings add knowledge on how tumor cells may respond to microenvironmental changes that affect their cell volume or metabolic crosstalk.
- Microenvironment-induced changes in expression of tumor-promoting RAC1B in colorectal cellsPublication . Pereira, Joana; Gonçalves, Vânia; Matos, Paulo; Jordan, PeterIntroduction: An inflammatory microenvironment is a tumor-promoting condition that provides survival signals to which cancer cells respond with changes in their gene expression. One key gene regulatory mechanism that responds to extracellular signals is alternative splicing. For example RAC1B, a RAC1 alternative splicing variant, that we previously identified in a subset of BRAF-mutated colorectal tumors, was found increased in samples from inflammatory bowel disease patients or following experimentally-induced acute colitis in a mouse model.The main goal of this work is to determine the pro-inflammatory signals from stromal cells that lead to increased RAC1B expression in colorectal cells. Material and Methods: Caco-2 colorectal cells were either grown as polarized cell monolayer on porous filter membranes and then co-cultured with different stromal cell lines (fibroblasts, monocytes and macrophages) or grown as cysts in 3D matrices. RAC1B expression was analyzed by RT-PCR, Western blot and confocal fluorescence microscopy. Results and Discussions: Culture conditions for polarized 2D and 3D models were established as physiologically more relevant colon cell models. Co-culture experiments with polarized cells revealed that the presence of fibroblasts and/or M1 macrophages induced a transient increase in RAC1B protein levels in the colorectal cells, accompanied by a progressive loss of epithelial organization. The cytokines secreted by stromal cells are currently being identified. Conclusion: Our data indicate that extracellular signals from stromal cells can affect gene expression in colorectal cancer cells. The observed increase in alternatively spliced RAC1B will help to understand the tumor-promoting effect of inflammation and identify novel therapeutic strategies.