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•Further deepening in interfacial properties of PLA nanocomposites with organo-clay.•Role of PBAT in morphology evolution and polymer chain mobility.•The level of interactions in the ...nanocomposites was probed using the CRR concept.•Higher degree of cooperativity in exfoliated structures compared to intercalated ones.•In semi-crystalline samples, the interaction level is independent on the morphology.
The concept of Cooperative Rearranging Region (CRR), an efficient probe of the interaction level in nanocomposites, has been used in Poly(lactic acid) (PLA)-based composites with phyllosilicates prepared in the melt with organomontmorillonite (O-MMT) and using poly(butylene adipate-co-terephthalate) (PBAT) as coupling agent. The samples were crystallized from various thermal treatments in order to obtain a wide range of morphologies and microstructures and accurately characterized by XRD, TEM, standard DSC and MT-DSC with the aim to highlight the effect of lamellae dispersion and distribution at nanoscale onto the thermal features of resulting nanocomposites. The presence of different interaction levels at the interface PLA/O-MMT, even tuned by the presence of PBAT, affects both the crystalline phase structure (by differently promoting crystallization of α and α′ forms) and the distribution between the amorphous fractions (rigid and mobile). The variations of molecular dynamics are classified in two categories depending on the composite microstructure. Only in amorphous materials the cooperativity is driven by the filler/matrix interactions. In semi-crystalline materials, the morphological features linked to the presence of O-MMT and PBAT are overwhelmed by the confinement of the amorphous phase. Comparison between the two crystallization modes evidences a stronger change in the glass transition dynamics for systems exhibiting preponderant nucleation and high percentage of rigid amorphous fraction.
α-Tocopherol, a natural antioxidant molecule, was physically immobilized on the outer surface of multi-walled carbon nanotubes (CNTs), and the resulting functionalised particles (f-CNTs) were ...dispersed in ultra-high molecular weight polyethylene aiming at improving its thermo-oxidation resistance. The success of the functionalization was assessed through spectroscopic and thermal analysis, and the influence of the filler on the thermo-oxidative stability of the nanocomposites was investigated through rheological analyses and infrared spectroscopy. We found that the addition of only 1wt.% of f-CNTs brings about a surprisingly high oxidation resistance, with a five/ten-fold increase of the induction time of the degradation phenomena. Rather than to the inherent stabilizing action of the α-tocopherol, such a notable result is believed to be due to its specific chemical interactions with the CNTs, which could exhibit a considerable radical scavenging activity due to the formation of structural defects on their outer surface. The latter represent acceptor-like localized states, which radically improve the thermo-oxidative resistance of the f-CNTs-based polymer nanocomposites.
Global and regional longitudinal strain (GLS-RLS) assessed by two-dimensional speckle tracking echocardiography (2D-STE) are considered reliable indexes of left-ventricular (LV) function and ...myocardial viability in chronic ischaemic patients when compared with delayed-enhanced cardiac magnetic resonance (DE-CMR). In the present study, we tested whether GLS and RLS could also identify early myocardial dysfunction and transmural extent of myocardial scar in patients with acute ST elevation myocardial infarction (STEMI) and relatively preserved LV function.
Twenty STEMI patients with LVEF ≥40%, treated with PPCI within 6 h from symptoms onset, underwent DE-CMR and 2D-echocardiography for 2D-STE analysis 6 ± 2 days after STEMI. Wall motion score index (WMSI) and LV ejection fraction (LVEF) were calculated by both methods. Infarct size and transmural extent of necrosis were assessed by CMR. GLS and RLS were obtained by 2D-STE. Mean GLS of the study population was -14 ± 3.3, showing a significant correlation with both LVEF and WMSI, by CMR (r = -0.86, P = 0.001, and r = 0.80, P = 0.001, respectively) and time-to-PCI (r = 0.66, P = 0.038). A weaker correlation was found between GLS and LVEF and WMSI assessed by 2D-echo (r = -0.65, P = 0.001, and r = 0.53, P = 0.013, respectively). RLS was significantly lower in DE-segments when compared with normal myocardium (P < 0.0001). A cut-off value of RLS of -12.3% by receiver-operating characteristic (ROC) curves identified DE-segments (sensitivity 82%, specificity 78%), whereas a cut-off value of -11.5% identified transmural extent of DE (sensitivity 75%, specificity 78%).
Our findings indicate that RLS and GLS evaluation provides an accurate assessment of global myocardial function and of the presence of segments with transmural extent of necrosis, with several potential clinical implications.
Hindered Amine Light Stabilizer (HAS) molecules have been covalently linked on the outer surface of multi-walled carbon nanotubes (CNTs), and the so-obtained multi-functional fillers (HAS-f-CNTs) ...have been compounded with Ultra High Molecular Weight Polyethylene (UHMWPE) to get composite films. The success of the grafting reaction of the HAS molecules has been confirmed through spectroscopic and thermo-gravimetric analyses. Morphological analyses reveal a segregated microstructure, in which CNT-rich channels surround the polymer domains. This morphology results in improved mechanical properties and appreciable electrical conductive features. More importantly, the addition of only 1 wt.% of HAS-f-CNTs brings about a significant improvement of the photo-oxidation resistance, which neither HAS nor CNTs can provide if used separately. The origin of this synergic effect is discussed. Overall, our results demonstrate the possibility of using properly functionalized CNTs as multi-functional fillers to get high-performance polymer composites.
Left ventricular (LV) diastolic filling is characterized by the formation of a vortex that supports an efficient transit into systolic ejection. Aim of this study was to assess the intraventricular ...(IV) blood flow dynamics among patients with ST elevated myocardial infarction (STEMI) at different degrees of LV dysfunction, in the attempt to find novel indicators of LV pump efficiency.
Sixty-four subjects, 34 consecutive STEMI patients and 30 healthy controls, underwent before hospital discharge 2D speckle tracking echocardiography to assess global longitudinal strain (GLS), and echo-particle image velocimetry analysis to assess flow energetic parameters. Left ventricular volumes ejection fraction (LVEF) and global wall motion score index (GWMSI) were evaluated by 3D echocardiography. ST elevated myocardial infarction patients were subdivided into three groups according to LVEF. Energy dissipation, vorticity fluctuation, and kinetic energy fluctuation indexes, which characterize the degree of disturbance in the flow, exhibit a biphasic behaviour in STEMI patients when compared with controls, with the highest values in patients with still preserved LV function and progressive lower values with LV function worsening. Significant linear correlations were found between energy dissipation index and both LVEF and GLS (r = 0.57, P < 0.001 and r = -0.61, P = 0.001, respectively). Kinetic energy fluctuation index significantly correlates with both LVEF (r = 0.75, P < 0.001) and GLS (-0.58, P = 0.002). Finally, a significant correlation was observed between GWMSI and energy dissipation index (-0.56, P = 0.008).
The present study describes, for the first time, the progression of IV flow energetic properties in patients with acute myocardial infarction at different stages of LV dysfunction when compared with healthy controls. Further data are needed to assess the role of these parameters in the development and maintenance of LV dysfunction.
Low molecular weight polyesters were end-functionalized with ammonium and carboxylate salts and used in ionic exchange reactions with respectively cationic (MMT) and anionic (LDH) clays. The hybrid ...organic-inorganic substrates were structurally analysed to determine the ester oligomers' modification degree and their thermal behaviour owing to confinement effects. The dispersion of such hybrids in polylactic acid (PLA) matrix was performed and the ultimate structural, morphological and thermal properties of the collected nanocomposites were investigated and correlated to the tailored interfacial properties with the different inorganic substrates. While the composites with MMT proved to be stable under thermo-oxidative conditions, the samples obtained by dispersing the LDH hybrid suffered from poor final thermostability owing to molecular weights decrease. Deeper insights about the effect of the interactions at interface (polymer chain-surfactant and polymer chain- inorganic surface) evidenced that by promoting an intimate contact between PLA chains and LDH surface (through oligoester used as inorganic substrate modifier) a certain extent of PLA hydrolysis triggered by both surfactant and inorganic surface (LDH) occurred and cannot completely avoided.
Current guidelines recommend an implantable cardiac defibrillator (ICD) in patients with symptomatic heart failure and reduced ejection fraction (HFrEF; left ventricular ejection fraction LVEF ≤35%) ...despite ≥3 months of optimal medical therapy. Recent observations demonstrated that sacubitril/valsartan induces beneficial reverse cardiac remodeling in eligible HFrEF patients. Given the pivotal role of LVEF in the selection of ICD candidates, we sought to assess the impact of sacubitril/valsartan on ICD eligibility and its predictors in HFrEF patients.
We retrospectively evaluated 48 chronic HFrEF patients receiving sacubitril/valsartan and previously implanted with an ICD in primary prevention. We assumed that ICD was no longer necessary if LVEF improved >35% (or >30% if asymptomatics) at follow-up.
Over a median follow-up of 11 months, sacubitril/valsartan induced a significant drop in LV end-systolic volume (-16.7 ml/m2, p=0.023) and diameter (-6.8 mm, p=0.022), resulting in a significant increase in LVEF (+3.9%, p<0.001). As a consequence, 40% of previously implanted patients resulted no more eligible for ICD at follow-up. NYHA class improved in 50% of the population. A dose-dependent effect was noted, with higher doses associated to more reverse remodeling. Among patients deemed no more eligible for ICD, lower NYHA class (odds ratio (OR) 3.73 95% CI 1.05; 13.24, p=0.041), better LVEF (OR 1.23 95% CI 1.01; 1.48, p=0.032) and the treatment with the intermediate or high dose of sacubitril/valsartan (OR 5.60 1.15; 27.1, p=0.032) were the most important predictors of status change.
In symptomatic HFrEF patients, sacubitril/valsartan induced beneficial cardiac reverse remodeling and improved NYHA class. These effects resulted in a significant reduction of patients deemed eligible for ICD in primary prevention.
Abstract
Background
pacemaker induced cardiomyopathy or transient impairment of the left ventricle (LV) function could be common collateral effects of the prolonged right ventricle (RV) pacing in ...patients with a pacemaker (PM) and pre-existing intra-ventricular conduction disturbances. However, the impact of RV pacing-site on RV performance of patients with right bundle branch block(RBBB) is still under-investigated.
Purpose
to study the effects of RV pacing in the mid-septal versus apical site on the morpho-functional performance of RV in patients undergoing permanent PM implantation.
Methods
We prospectively enrolled consecutive patients with a pre-existent complete RBBB and undergoing dual-chamber PM implantation in our institution. We randomized the patients 1:1 to receive the RV catheter fixed either in the apex or in the mid-septal position. Patients with LV systolic dysfunction (LVEF <50%), severe valvulopathies, left bundle branch block (LBBB), or preserved intraventricular conduction were excluded. Patients who received PM implantation were evaluated both at baseline and after two months with a 12-lead ECG, 2D, and 3D echocardiogram with analysis focused on RV performance according to the guidelines of the European Association of Cardiovascular Imaging.
Results
a total of 22 patients were randomized in the study, 11 (50%) received RV catheter positioned in the apex and 11 (50%) in the mid-septum, respectively. No baseline differences were recorded between the two groups in clinical characteristics, ECG and echocardiographic parameters. At 2 months follow up, there were no statistically significant difference in the % of RV pacing between the two groups. Nonetheless, RV mid-septal group showed significantly shorter duration of the stimulated QRS (146 ± 12 msec vs. 161 ± 20 msec, p = 0.05), significantly reductions in the RV dimensions (pre: 42 ± 8 mm vs. post: 37 ± 7 mm, p = 0.05) telediastolic area (pre: 12 ± 3 cm2/m2 vs post: 9 ± 4 cm2/ m2, p = 0.02) telediastolic volume (pre: 55 ± 16 ml/m2 vs post: 50 ± 17 ml/m2, p = 0.02) and a significant improvement of RV ejection fraction (pre: 54 ± 9% vs post: 57 ± 11%, p = 0.02) than patients in the RV-apical group. Moreover, patients in the RV-apical group showed significant lowering in the GLS of the LV (pre: -16 ± 3% vs post: -11.7 ± 3%, p <0.001) and in the TAPSE (pre: 23 ± 5 mm vs post: 21 ± 2, p = 0.07) at follow up.
Conclusions
In this study, mid-septal pacing seems associated with a better morpho-functional RV performance than apical pacing in patients with pre-existent RBBB undergoing permanent PM implantation.
Abstract
Background
ICD implantation is recommended for primary prevention in patients with symptomatic NYHA II-III heart failure with reduced ejection fraction (< 35%) (HFrEF) and without left ...ventricle ejection fraction (LVEF) improvement despite at least three months of guideline-directed therapy. The use of angiotensin receptor-neprilysin inhibition with LCZ696 has shown to ameliorate left ventricle function and to reduce the ventricular arrhythmias burden in patients with HFrEF.
Purpose
The profile of patients with HFrEF who may benefit from therapy with LCZ696 without further requiring an ICD in primary prevention is still unknown. We aimed to assess the prevalence of these patients and to find potential clinical predictors of responsiveness to this treatment.
Methods
We enrolled consecutive patients that started LCZ696 treatment for medical therapy optimization in the heart failure clinic of our institution. All of them were previously implanted with an ICD before LCZ696 availability (from 2009 to 2015). A cardiologist evaluated their home medications, clinical, and echocardiographic characteristics both at baseline (before starting LCZ696) and during follow up. The patients were grouped also according to the etiology of HF (ischemic/non-ischemic) and by gender. Patients were excluded if candidates to cardiac resynchronization therapy. Responsiveness to LCZ696 treatment was defined as an increase of LVEF to values > 35% at follow up (FU).
Results
A total of 49 patients (67.1 ± 9.8 years of age) were enrolled in this study and followed in the heart failure clinic of our institution (mean follow up 11.5 ± 4.9 months). Among them, 19 patients (38%) showed an increase in LVEF to values > 35% at follow up and a significant improvement in LVEF was appreciated (baseline LVEF: 31.2 ± 4.5 vs. follow up LVEF: 35.4 ± 8.0; p 0.003). No significant differences were recorded at baseline in LVEF within HF etiology and gender groups. At follow up, we found a significant increase in post-therapy LVEF only in the non-ischemic etiology group (from 31.5 ± 4.4 to 37.1 ± 8.1, p = 0.001) and in the male group (from 31.4 ± 4.5 to 34.9 ± 7.9, p = 0.005) in comparison with the ischemic etiology and the female group, respectively. No significant statistical differences were appreciated between responders and non-responders neither in terms of home medications nor in the LCZ696 doses, both at baseline and follow up.
Conclusion
This study suggests a potential impact of angiotensin receptor-neprilysin inhibition therapy in the selection of patients with HFrEF candidates to ICD in primary prevention. In this real-world experience from our HF clinic, we found a significant LVEF improvement in approximately 40% of patients treated with LCZ696. These patients, in FU evaluation, would not have needed for an ICD implantation. This benefit appears related to the non-ischemic etiology of HF and the male gender.
Abstract Figure. LVEF VARIATIONS
9-Anthroylacetone and its photodimer Cicogna, Francesca; Ingrosso, Giovanni; Lodato, Fabio ...
Tetrahedron,
12/2004, Letnik:
60, Številka:
51
Journal Article
Recenzirano
9-Anthroylacetone undergoes a head-to-tail 4π+4π photo-dimerisation reaction that leads to the formation of 5,11-bis(1,3-diketobutyl)-5,6,11,12-tetrahydro-5,12,6,11-di-
o-benzeno-dibenzo
a,
...ecyclooctene both in solution and in the solid state when irradiated with different sources (sunlight, tungsten lamp, xenon lamp, UV laser beam 351–364
nm), the reaction being accompanied by a colour variation from bright yellow to colourless. Quantum yields >0.023
mol/Einstein are evaluated for the solid state reaction. Interestingly, the dimer dissociates to give 9-anthroylacetone, both thermally (
T>130
°C) and photochemically, by short UV wavelength irradiation. The single-crystal X-ray structure of 9-anthroylacetone and its dimer are reported.
9-Anthroylacetone undergoes a head-to-tail 4π+4π photo-dimerisation reaction both in solution and in the solid state when irradiated with different sources; the dimer reversibly dissociates into 9-anthroylacetone, both thermally and photochemically.
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