Monitoring temporal variations in the geothermal activity of Miocene Lesvos volcanic field using remote sensing techniques and MODIS – LST imagery

Many islands of the Aegean Sea show strong geothermal activity due to volcanism in the area. In this paper, Robust Satellite Techniques (RST) are used to isolate, from other known possible sources, those thermal anomalies possibly related to geothermal activity in the Miocene volcanic field of Lesvos Island (Northern Aegean). For this purpose, 12 years (2003–2014) of daily Night-time Land Surface Temperature (LST) products, from Moderate Resolution Imaging Spectroradiometer (MODIS) acquisitions were analyzed. The final dataset contained 770 thermal anomalies whose spatial correlation with geological and structural data of Lesvos - such as caldera rims, ring faults, major tectonic lineaments and hydrothermal alterations mapped by processing SENTINEL-2 MSI satellite images – has been particularly investigated. In the approximately 20 ma geothermal field of Lesvos, geothermal activity seems to be also associated with the extensional regime of the broader area that leads to lithosphere thinning and consequent heat transfer in the multi-fractured terrain of Lesvos through volcanic and tectonic faults. Achieved results seem to confirm the possibility to use RST-based thermal anomalies to identify temporal variations in the geothermal activity probably due to the uplifting and circulation of the hydrothermal waters. © 2020 The Author

Monitoring temporal variations in the geothermal activity of Miocene Lesvos volcanic field using remote sensing techniques and MODIS – LST imagery

Many islands of the Aegean Sea show strong geothermal activity due to volcanism in the area. In this paper, Robust Satellite Techniques (RST) are used to isolate, from other known possible sources, those thermal anomalies possibly related to geothermal activity in the Miocene volcanic field of Lesvos Island (Northern Aegean). For this purpose, 12 years (2003–2014) of daily Night-time Land Surface Temperature (LST) products, from Moderate Resolution Imaging Spectroradiometer (MODIS) acquisitions were analyzed. The final dataset contained 770 thermal anomalies whose spatial correlation with geological and structural data of Lesvos - such as caldera rims, ring faults, major tectonic lineaments and hydrothermal alterations mapped by processing SENTINEL-2 MSI satellite images – has been particularly investigated. In the approximately 20 ma geothermal field of Lesvos, geothermal activity seems to be also associated with the extensional regime of the broader area that leads to lithosphere thinning and consequent heat transfer in the multi-fractured terrain of Lesvos through volcanic and tectonic faults. Achieved results seem to confirm the possibility to use RST-based thermal anomalies to identify temporal variations in the geothermal activity probably due to the uplifting and circulation of the hydrothermal waters

Evaluation of two novel antioxidants with differential effects on curcumin-induced apoptosis in C2 skeletal myoblasts; involvement of JNKs

Excessive levels of reactive oxygen species (ROS) result in numerous pathologies including muscle disorders. In essence, skeletal muscle performance of daily activities can be severely affected by the redox imbalances occurring after muscular injuries, surgery, atrophy due to immobilization, dystrophy or eccentric muscle contraction. Therefore, research on the potential beneficial impact of antioxidants is of outmost importance. In this context, aiming at further exploring the mechanisms of action of our newly synthesized antioxidant compounds (AK1 and AK2) in a skeletal muscle experimental setting, we initially investigated their scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and subsequently assessed their effect on the viability of C2 skeletal myoblasts in the presence of two pro-oxidants: H2O2 and curcumin (MTT assay). Interestingly, while both compounds reversed the detrimental effect of H2O2, only AK2 was cytoprotective in curcumin-treated C2 cells. We next confirmed the immediate activation of extracellular signal-regulated kinases (ERKs) and the more delayed activation profile of c-Jun NH2-terminal kinases (JNKs) in C2 skeletal myoblasts exposed to curcumin, by Western blotting. In correlation with the aforementioned results, only AK2 blocked the curcumin-induced activation of JNKs pathway. Furthermore, JNKs were revealed to mediate curcumin-induced apoptosis in C2 cells and only AK2 to effectively suppress it (by detecting its effect on poly(ADP-ribose) polymerase fragmentation). Overall, we have shown that two similar in structure novel antioxidants confer differential effects on C2 skeletal myoblasts viability under oxidative stress conditions. This result may be attributed to these antioxidants respective diverse mode of interaction with the signaling effectors involved in the observed responses. Future studies should further evaluate the mechanism of action of these compounds in order to support their potential application in therapeutic protocols against ROS-related muscle disorders. © 2015 Published by Elsevier Ltd

Cardiovascular phenotype of mice lacking 3-mercaptopyruvate sulfurtransferase

Rationale: Hydrogen sulfide (H2S) is a physiological mediator that regulates cardiovascular homeostasis. Three major enzymes contribute to the generation of endogenously produced H2S, namely cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). Although the biological roles of CSE and CBS have been extensively investigated in the cardiovascular system, very little is known about that of 3-MST. In the present study we determined the importance of 3-MST in the heart and blood vessels, using a genetic model with a global 3-MST deletion. Results: 3-MST is the most abundant transcript in the mouse heart, compared to CSE and CBS. 3-MST was mainly localized in smooth muscle cells and cardiomyocytes, where it was present in both the mitochondria and the cytosol. Levels of serum and cardiac H2S species were not altered in adult young (2–3 months old) 3-MST−/− mice compared to WT animals. No significant changes in the expression of CSE and CBS were observed. Additionally, 3-MST−/− mice had normal left ventricular structure and function, blood pressure and vascular reactivity. Interestingly, genetic ablation of 3-MST protected mice against myocardial ischemia reperfusion injury, and abolished the protection offered by ischemic pre- and post-conditioning. 3-MST−/− mice showed lower expression levels of thiosulfate sulfurtransferase, lower levels of cellular antioxidants and elevated basal levels of cardiac reactive oxygen species. In parallel, 3-MST−/− mice showed no significant alterations in endothelial NO synthase or downstream targets. Finally, in a separate cohort of older 3-MST−/− mice (18 months old), a hypertensive phenotype associated with cardiac hypertrophy and NO insufficiency was observed. Conclusions: Overall, genetic ablation of 3-MST impacts on the mouse cardiovascular system in an age-dependent manner. Loss of 3-MST exerts a cardioprotective role in young adult mice, while with aging it predisposes them to hypertension and cardiac hypertrophy. © 2020 Elsevier Inc

Adenosine receptors in gestational diabetes mellitus and maternal obesity in pregnancy

Regulation of blood flow depends on the systemic and local release of vasoactive molecules including the endogenous nucleoside adenosine. Vasodilation caused by adenosine results from the activation of adenosine receptors (ARs) at the vascular endothelium and smooth muscle. Adenosine receptors are four subtypes, i.e. AAR, AAR, AAR and AAR, of which AAR and AAR activation in the endothelium lead to increased generation of nitric oxide and relaxation of the underlying smooth muscle cell layer. Adenosine also causes vasoconstriction via a mechanism involving AAR activation by increasing the release of vasoconstrictors. Adenosine increases the sensitivity of vascular tissues from diseases coursing with insulin resistance, including gestational diabetes mellitus (GDM) and obesity. ARs also play a role in obesity since they modulate D-glucose homeostasis, inflammation and adipogenesis. Agonists and/or antagonists of high selectivity for ARs may result in reversing the obesity state since normalises lipolysis and insulin sensitivity. A considerable fraction of pregnant women with GDM show with pregestational obesity and/or supraphysiological gestational weight gain. These conditions associated with reduced vascular responsiveness to adenosine and insulin. However, it is unclear whether GDM plus obesity in pregnancy could worsen these alterations in the foetoplacental vascular function. This chapter summarises available findings that address the potential involvement of ARs to modulate human foetoplacental vasculature in GDM and obesity in pregnancy