scholarly journals Key factors behind autofluorescence changes caused by ablation of cardiac tissue

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Narine Muselimyan ◽  
Huda Asfour ◽  
Narine Sarvazyan

Abstract Radiofrequency ablation is a commonly used clinical procedure that destroys arrhythmogenic sources in patients suffering from atrial fibrillation and other types of cardiac arrhythmias. To improve the success of this procedure, new approaches for real-time visualization of ablation sites are being developed. One of these promising methods is hyperspectral imaging, an approach that detects lesions based on changes in the endogenous tissue autofluorescence profile. To facilitate the clinical implementation of this approach, we examined the key variables that can influence ablation-induced spectral changes, including the drop in myocardial NADH levels, the release of lipofuscin-like pigments, and the increase in diffuse reflectance of the cardiac muscle beneath the endocardial layer. Insights from these experiments suggested simpler algorithms that can be used to acquire and post-process the spectral information required to reveal the lesion sites. Our study is relevant to a growing number of multilayered clinical targets to which spectral approaches are being applied.

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 116
Author(s):  
Gian Luca Chiarello ◽  
Ye Lu ◽  
Miren Agote-Arán ◽  
Riccardo Pellegrini ◽  
Davide Ferri

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.


2014 ◽  
Vol 458 (2) ◽  
pp. 187-193 ◽  
Author(s):  
María Fernández-Velasco ◽  
Silvia González-Ramos ◽  
Lisardo Boscá

Emerging evidence points to the involvement of specialized cells of the immune system as key drivers in the pathophysiology of cardiovascular diseases. Monocytes are an essential cell component of the innate immune system that rapidly mobilize from the bone marrow to wounded tissues where they differentiate into macrophages or dendritic cells and trigger an immune response. In the healthy heart a limited, but near-constant, number of resident macrophages have been detected; however, this number significantly increases during cardiac damage. Shortly after initial cardiac injury, e.g. myocardial infarction, a large number of macrophages harbouring a pro-inflammatory profile (M1) are rapidly recruited to the cardiac tissue, where they contribute to cardiac remodelling. After this initial period, resolution takes place in the wound, and the infiltrated macrophages display a predominant deactivation/pro-resolution profile (M2), promoting cardiac repair by mediating pro-fibrotic responses. In the present review we focus on the role of the immune cells, particularly in the monocyte/macrophage population, in the progression of the major cardiac pathologies myocardial infarction and atherosclerosis.


2019 ◽  
Vol 57 (8) ◽  
pp. 1136-1141
Author(s):  
François Rousseau ◽  
Carmen Lindsay ◽  
Yves Labelle ◽  
Yves Giguère

Abstract Background The process of technology validation and transfer of new molecular diagnostic tests towards the clinic faces challenges and needs to be improved. There is no empirical measure of the chronology and pace of technology transfer of molecular genetic discoveries. Methods We studied these for 29 molecular genetic test discoveries in order to (1) provide estimates of the timeframe between discovery of a clinical application and complete clinical implementation, and (2) compare the trajectories between different new tests to identify common patterns. We identified 11 publicly available “timestamps” for the technology transfer process ranging from discovery of the marker to use in a clinical setting. For each test selected, we searched public databases to identify available timestamps and dates. We plotted and compared trajectories of individual tests, including chronology. Results We show that there is much variability in the chronology of transfer between biomarkers. The median time between discovery of the marker and availability of the clinical test was 9.5 years (minimum 1). There was a median time of 18 years between test discovery and FDA approval (minimum 7 years), and it took a median of 17 years between discovery and the availability of a certified reference material for the 10 assays that have one (minimum 9 years). Conclusions We conclude that new molecular genetic tests take significant time between discovery and clinical implementation, and that further work is needed to pinpoint key factors, including policy and organization factors, that may allow for improving and streamlining this process.


Author(s):  
Ömer Alkan ◽  
İkram Yusuf Yarbaşı

The main objective of this study is to determine key factors that may have a significant effect on alcohol consumption in Turkey. For this purpose, the cross-sectional data obtained from the Turkish Health Survey conducted in 2010 and 2012 by the Turkish Statistical Institute were analyzed through the multinomial probit model. Results revealed that several key variables were found to be a significant determinant of alcohol consumption, such as gender, age, education, marital status, income, general health status, tooth brushing frequency, situation of violence, fruit consumption frequency, tobacco use, exposure to tobacco smoke, and survey year. It is apparent that alcoholics need help to get rid of an addiction. Therefore, it would be inevitable for governments to intervene through national and international public health authorities. In particular, the ability of governments to design and implement comprehensive prevention strategies that combine the strengths of different policy approaches is critical to success.


2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Mohammed Aljishi ◽  
Huda Asfour ◽  
Tigran Chahbazian ◽  
Narine Muselimyan ◽  
Luther Swift ◽  
...  

Persistent atrial fibrillation is commonly treated using an endoscopic catheter to eliminate anomalous sources of cardiac activity via thermal ablation. However, the procedure lacks real-time feedback. Newly developed radiofrequency ablation (RFA) catheters include a fiberoptic bundle through which visual information of tissue conditions may be collected offering an opportunity to reveal subtle differences in tissue physiology. Currently little is known about the spectral changes caused by RFA. We hypothesized that by comparing spectral changes in various areas in the heart before and after RFA, optical signatures can be used to distinguish healthy cardiac tissue from thermally ablated tissue. Excitation emission matrices (EEM) were acquired from excised porcine hearts (300-600nm). Distinct EEMs were collected from the endocardium of the left atria, ventricle, and aorta. Additionally, the fluorescence and reflectance profiles of each tissue were altered by thermal ablation. In the ventricular muscle, a reduction in the NADH fluorescence peak (360/460nm excitation/emission maxima) was most prominent. While in the aorta, collagen and elastin fluorescence peaks fused and broadened upon ablation. Changes in atrial tissue included a drop in NADH fluorescence and an overall increase in reflectance. The latter is likely caused by thermal coagulation of heme-containing proteins such as myoglobin and a weaker absorption within the Soret band. We concluded that optical signals revealed by EEMs offer quantitative information that can be used to develop diagnostic catheters, including hyperspectral imaging protocols to discern spectral changes elicited by RFA treatment.


2020 ◽  
Vol 10 (4) ◽  
pp. 103
Author(s):  
Jorge Vieira ◽  
Rui Frade ◽  
Raquel Ascenso ◽  
Inês Prates ◽  
Filipa Martinho

In recent years, tourism has experienced remarkable growth worldwide. This sector is rapidly becoming the main export activity and the most important source of GDP growth in several countries. In Portugal, it represented around 19.7% of exports in 2019. The internet and online platforms contributed decisively to this growth. Generation Z already represents a considerable portion of society and, in the coming years, will become the central consumer segment. With this research, we intend to identify the key factors in the decision to purchase online, in Generation Z individuals, in the Portuguese tourism sector. We carried out a characterization of the sector, a bibliographic review and the identification of key variables. We applied a structured questionnaire to a sample of 233 individuals aged between 10 and 25 years. Subsequently, the data were processed using descriptive methodologies and association tests between variables. The key factors in the decision to purchase tourism products/services in Generation Z are Trust, Price, the use of aggregating websites, WOM/EWOM, the Offer of products/services online and the Online experience. In the opposite direction, it was given less importance to Convenience, Reviews on tourism websites, Tourism Advertising, Social networking and the possibility of Canceling the reservation. This study allows us to establish the bases for future research, to help researchers to understand Generation Z consumption habits.


10.28945/4232 ◽  
2019 ◽  
Vol 3 ◽  
pp. 041-054
Author(s):  
Marlo B Murphy-Braynen

The paper uses a mixed method approach to conduct a literature review of existing econometric studies to determine the key drivers of export diversification and economic growth, and to examine whether export diversification propels or hinders economic growth. The paper differs fundamentally from previous studies, as it focuses on identifying the key variables used, the frequency with which they are used and their degree of significance based on econometric studies that focused on measuring export diversification, economic growth and the linkage between diversification and growth in developed and developing countries, while highlighting a key gap in this literature, namely a lack of empirical studies focused on small island states. The paper finds that eight variables were used across all studies at a frequency of 10% or greater – namely, real GDP per capita, education, population, domestic investment, market distance, openness to trade, export concentration and rule of law. Based on the literature review, the key factors which support export diversification are human capital accumulation inclusive of higher education, domestic investment, population, quality of institutions, quality of infrastructure and market access. Conversely the factors that retard export diversification or increase export concentration are economic distance (remoteness from major markets), openness to trade, and declining terms of trade, foreign direct investment, exchange rate volatility and exchange rate overvaluation. Similarly, with regards to economic growth, the literature review suggests that the key factors which promote economic growth are rule of law, investment ratio, favorable movements in the terms of trade, technology, higher education and increased international openness while the factors that inhibit economic growth are fertility rate, the ratio of government consumption to GDP, and the inflation rate. In terms of the key variables used to link export diversification to economic growth, based on the literature, the six main categories of trade integration variables include export composition, trade orientation, export structure, geographic structure and trade strategy. After having reviewed the extant literature on export diversification and its relationship to economic growth, one of the overlooked areas of research is a lack of studies examining export diversification in small island developing states, and how export diversification may or may not contribute to economic growth in those particular contexts.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Samuel Ribeiro-Navarrete ◽  
Daniel Palacios-Marqués ◽  
José María Martín Martín ◽  
José Manuel Guaita Martínez

PurposeThis study contributes to the limited literature on crowdlending by providing a data-driven analysis of the sector. A synthetic DP2 indicator is proposed to identify the leaders of the crowdlending market, the key factors behind their success and the medium-term competitive implications.Design/methodology/approachThe study examines 17 crowdlending platforms and eight performance indicators. The information provided by these indicators is aggregated using a synthetic indicator based on the P2 Distance (DP2) method.FindingsMintos, Evoestate, Peerberry, Bondster and Fellow Finance are the leading platforms. This method reveals the key variables in the identification of market leaders, namely year-on-year variation in the number of investors and year-on-year variation in lending per investor. The leaders in terms of lending volumes should not take their current situation for granted. Small and medium-sized platforms are pushing hard and may overtake the incumbents as market leaders.Practical implicationsFinancial intermediation through crowdlending is becoming an increasingly popular alternative to traditional models. Changes in the sector are expected in the coming years due to the rise of platforms with a moderate amount of lending and solid year-on-year improvement. To become leaders and to attract both lenders and borrowers, platforms are encouraged to improve the information that they provide.Originality/valueThis paper offers the first analysis of market leadership in the crowdlending sector. It analyses the competitive market of the crowdlending sector based on its actors and key factors. These factors explain the differences in the market position of different platforms. Based on this analysis, the trends in this sector can be identified. This study is exploratory, so it offers empirical data that can be useful in the development of theories that apply to the sector.


2016 ◽  
Vol 110 (3) ◽  
pp. 494a
Author(s):  
Mohammed Aljishi ◽  
Huda Asfour ◽  
Luther Swift ◽  
Narine Muselimyan ◽  
Tigran Chahbazian ◽  
...  

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