Role of humidity in the development and intensification of Mediterranean tropical-like cyclones (Medicanes)

In questo lavoro sono stati analizzati due casi di ”tropical-like cyclones” nel Mediterraneo, anche noti come Medicane, facendo uso di simulazioni numeriche del modello WRF (versione 4.1). Le simulazione numeriche sono state effettuate usando il supercomputer Cheyenne dell’NCAR-Wyoming Supercomputing Center (NWSC) e inizializzate con i dati di ERA5, l’ultima generazione di reanalisi meteorologiche dell’ECMWF. Questi casi, che sono stati recentemente analizzati nell’articolo di Miglietta e Rotunno (2019), sono stati riconsiderati qui per porre l’attenzione sull’origine dell’aria umida nei bassi strati atmosferici che precondiziona favorevolmente l’ambiente dove i cicloni si sviluppano. Nel primo Medicane erano presenti alti valori di umidità nei bassi strati atmosferici già prima che il ciclone si formasse, a causa degli intensi flussi superficiali dal mare nel Mediterraneo meridionale, associati ad aria secca e fredda proveniente dai Balcani orientali. Il secondo Medicane si intensifica fortemente nel momento in cui beneficia degli intensi flussi superficiali dal mare generati dall’irruzione dei venti di Tramontana e Cierzo vicino alla zona di formazione del ciclone. Benché limitati a questi due casi studio, i risultati delle simulazioni e dei test di sensibilità hanno identificato differenti condizioni ambientali favorevoli all’intensificazione dei Medicane nel Mediterraneo occidentale e meridionale, e dimostrano perché queste due aree sono considerate come hot spot per la formazione di questi fenomeni. Inoltre, è stato analizzato il ruolo dell’intrusione di aria secca d’alta quota nello sviluppo dei cicloni. Sono stati effettuati test di sensibilità dove è stata posta una condizione di minimo valore di umidità relativa (50%) nelle condizioni iniziali e nelle condizioni al contorno. Per entrambi i casi, è stato trovato che l’aumento di umidità ha l’effetto di anticipare la formazione del ciclone, producendo vortici più intensi e duraturi

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

Significance: The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly. Critical Issues: Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population. Future Directions: Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly

Propofol inhibits prokaryotic voltage-gated Na+ channels by promoting activation-coupled inactivation

Propofol is widely used in the clinic for the induction and maintenance of general anesthesia. As with most general anesthetics, however, our understanding of its mechanism of action remains incomplete. Local and general anesthetics largely inhibit voltage-gated Na+ channels (Navs) by inducing an apparent stabilization of the inactivated state, associated in some instances with pore block. To determine the biophysical and molecular basis of propofol action in Navs, we investigated NaChBac and NavMs, two prokaryotic Navs with distinct voltage dependencies and gating kinetics, by whole-cell patch clamp electrophysiology in the absence and presence of propofol at clinically relevant concentrations (2-10 μM). In both Navs, propofol induced a hyperpolarizing shift of the pre-pulse inactivation curve without any significant effects on recovery from inactivation at strongly hyperpolarized voltages, demonstrating that propofol does not stabilize the inactivated state. Moreover, there was no evidence of fast or slow pore block by propofol in a non-inactivating NaChBac mutant (T220A). Propofol also induced hyperpolarizing shifts of the conductance-voltage relationships with negligible effects on the time constants of deactivation at hyperpolarized voltages, indicating that propofol does not stabilize the open state. Instead, propofol decreases the time constants of macroscopic activation and inactivation. Adopting a kinetic scheme of Nav gating that assumes preferential closed-state recovery from inactivation, a 1.7-fold acceleration of the rate constant of activation and a 1.4-fold acceleration of the rate constant of inactivation were sufficient to reproduce experimental observations with computer simulations. In addition, molecular dynamics simulations and molecular docking suggest that propofol binding involves interactions with gating machinery in the S4-S5 linker and external pore regions. Our findings show that propofol is primarily a positive gating modulator of prokaryotic Navs, which ultimately inhibits the channels by promoting activation-coupled inactivation. © 2018 Yang et al

Aging-Related Decline of Glutathione Peroxidase 3 and Risk of Cardiovascular Events in Patients With Atrial Fibrillation

BACKGROUND: Experimental studies demonstrated that glutathione peroxidase 3 (GPx3), an antioxidant enzyme that catabolizes hydrogen peroxide, protects against thrombosis. Little is known about its role in cardiovascular disease. METHODS AND RESULTS: A prospective cohort study was conducted in 909 atrial fibrillation patients. Serum activities of GPx3, superoxide dismutase (SOD), and catalase were measured at baseline to assess the risk of cardiovascular events during a mean follow-up of 43.4 months (3291 person-years). Serum Nox2 and urinary excretion of 11-deydro-thromboxane B2 were also measured. During follow-up 160 cardiovascular events occurred (4.9%/year). Significantly lower values of GPx3 (P<0.001) and SOD (P=0.037) were detected in patients with, compared to those without, cardiovascular events. A lower survival rate was observed in patients with GPx3 (P<0.001) and SOD (P=0.010) activities below the median, as compared to those above. In a fully adjusted Cox regression model, GPx3 was the only antioxidant enzyme predictor of cardiovascular events (hazard ratio 0.647, 95% confidence interval 0.524-0.798, P<0.001). GPx3 was inversely associated with urinary 11-dehydro-thromboxane B2 (B -0.337, P<0.001) and serum Nox2 (B: -0.423, P<0.001). GPx3 activity progressively decreased with decades of age (P<0.001), with a progressive reduction in people aged ≥70 years. CONCLUSIONS: This study provides evidence that a low antioxidant status, as depicted by reduced levels of GPx3, increases the risk of cardiovascular events in patients with atrial fibrillation. The age-related decline of GPx3 may represent a mechanism for the enhanced cardiovascular risk in the elderly population

Is there an interplay between adherence to mediterranean diet, antioxidant status, and vascular disease in atrial fibrillation patients?

Mediterranean Diet (Med-Diet) is associated with reduced incidence of vascular events (VEs) in atrial fibrillation (AF), but the mechanism accounting for its beneficial effect is only partially known. We hypothesized that Med-Diet may reduce VEs by improving antioxidant status, as assessed by glutathione peroxidase 3 (GPx3) and superoxide dismutase (SOD). We performed a prospective cohort study investigating the relationship between adherence to Med-Diet, serum baseline GPx3 and SOD activities, and the occurrence of VEs in 690 AF patients. GPx3 activity was directly associated with Med-Diet score (B = 0.192, p &lt; 0.001) and inversely with age (B = −0.124, p = 0.001), after adjustment for potential confounders; Med-Diet weakly affected SOD levels. During a mean follow-up of 46.1 ± 28.2 months, 89 VEs were recorded; patients with VEs had lower GPx3 levels compared with those without VEs (p = 0.002); and no differences regarding SOD activity were found. Multivariable Cox regression analysis showed that age (Hazard ratio [HR]:1.065, p &lt; 0.001), logGPx3 (above median, HR: 0.629, p &lt; 0.05), and Med-Diet score (HR: 0.547, p &lt; 0.05) predicted VEs. Med-Diet favorably modulates antioxidant activity of GPx3 in AF, resulting in reduced VEs rate. We hypothesize that the modulation of GPx3 levels by Med-Diet could represent an additional nutritional strategy to prevent VEs in AF patients

Gut-Derived Serum Lipopolysaccharide is Associated With Enhanced Risk of Major Adverse Cardiovascular Events in Atrial Fibrillation: Effect of Adherence to Mediterranean Diet

Gut microbiota is emerging as a novel risk factor for atherothrombosis, but the predictive role of gut-derived lipopolysaccharide (LPS) is unknown. We analyzed (1) the association between LPS and major adverse cardiovascular events (MACE) in atrial fibrillation (AF) and (2) its relationship with adherence to a Mediterranean diet (Med-diet)

Lipopolysaccharide as trigger of platelet aggregation via eicosanoid over-production

The effect of lipopolysaccharide (LPS) on platelet aggregation is still controversial. We performed in vitro and ex vivo studies in controls and in patients with community-acquired pneumonia (CAP) to assess the effect of LPS on platelet activation (PA). LPS (15-100 pg/ml) significantly increased PA only if combined with sub-threshold concentrations (STC) of collagen or ADP; this effect was associated with increased platelet H2O2 production, Nox2 activation, PLA2 phosphorylation, thromboxane (Tx)A2 and 8-iso-PGF2α-III, and was inhibited by aspirin, TxA2 receptor antagonist or by Toll-like receptor 4 blocking peptide (TLR4bp). Analysis of up-stream signalling potentially responsible for Nox2 and PLA2 activation demonstrated that LPS-mediated PA was associated with phosphorylation of AKT, p38 and p47phox translocation. In 10 consecutive CAP patients serum endotoxins were significantly higher compared to 10 controls (145 [115-187] vs 18 [6-21] pg/ml; p<0.01). Ex vivo study showed that agonist-stimulated platelets were associated with enhanced PA (p<0.01), Toll-like receptor 4 (TLR4) expression (p<0.05), thromboxane (Tx)A2 (p<0.01) and 8-iso-PGF2α-III (p<0.01) production in CAP patients compared to controls. The study provides evidence that LPS amplifies the platelet response to common agonists via TLR4-mediated eicosanoid production and suggests LPS as a potential trigger for PA in CAP

Is there an interplay between adherence to mediterranean diet, antioxidant status, and vascular disease in atrial fibrillation patients?

Mediterranean Diet (Med-Diet) is associated with reduced incidence of vascular events (VEs) in atrial fibrillation (AF), but the mechanism accounting for its beneficial effect is only partially known. We hypothesized that Med-Diet may reduce VEs by improving antioxidant status, as assessed by glutathione peroxidase 3 (GPx3) and superoxide dismutase (SOD). We performed a prospective cohort study investigating the relationship between adherence to Med-Diet, serum baseline GPx3 and SOD activities, and the occurrence of VEs in 690 AF patients. GPx3 activity was directly associated with Med-Diet score (B = 0.192, p &lt; 0.001) and inversely with age (B = −0.124, p = 0.001), after adjustment for potential confounders; Med-Diet weakly affected SOD levels. During a mean follow-up of 46.1 ± 28.2 months, 89 VEs were recorded; patients with VEs had lower GPx3 levels compared with those without VEs (p = 0.002); and no differences regarding SOD activity were found. Multivariable Cox regression analysis showed that age (Hazard ratio [HR]:1.065, p &lt; 0.001), logGPx3 (above median, HR: 0.629, p &lt; 0.05), and Med-Diet score (HR: 0.547, p &lt; 0.05) predicted VEs. Med-Diet favorably modulates antioxidant activity of GPx3 in AF, resulting in reduced VEs rate. We hypothesize that the modulation of GPx3 levels by Med-Diet could represent an additional nutritional strategy to prevent VEs in AF patients

HIV-1 induces in vivo platelet activation by enhancing platelet NOX2 activity.

OBJECTIVES: HIV-1 patients show increased platelet activation, but the mechanisms involved are not completely clarified. We speculated that HIV-1 might induce in vivo platelet activation by enhancing platelet NOX2-related oxidative stress. METHODS: We measured soluble CD40 Ligand (sCD40L), a systemic marker of platelet activation, in 36 HIV-1 patients under effective combined antiretroviral therapy (cART) and in 10 naïve HIV-1 subjects. As control, 20 healthy subjects (HS) were included. Platelet oxidative stress was measured by platelet NOX2-derived peptide (sNOX2-dp), p47(phox) translocation to platelet membrane and platelet prostaglandin F2α (8-iso-PGF2α). RESULTS: sCD40L was increased both in HIV-1 naïve and cART patients compared to HS (p &lt; 0.001). Platelet sNOX2-dp and 8-iso-PGF2α were significantly higher in HIV-1 naïve subjects compared to those on cART and to HS, and both were mutually correlated (R = 0.734, p &lt; 0.001). A stepwise multivariable linear regression analysis showed that platelet sNOX2-dp (β: 0.803, p &lt; 0.001), HIV-1 infection (β: 0.146, p = 0.014) and age (β: 0.166, p = 0.001) were independently associated to sCD40L levels. CONCLUSIONS: HIV-1 infection is associated with increased platelet oxidative stress, which was related to the activation of NOX2. The independent association between platelet NOX2 activation and plasma levels of sCD40L suggest that in vivo platelet activation may be dependent upon platelet oxidative stress