Decrease in phase angle after Roux-en-Y gastric bypass is related to increase of anti-inflammatory status

Background: Ventricular arrhythmias are a common clinical manifestation in patients with acute myocardial infarction submitted to coronary revascularizaton. Reperfusion arrhythmias have been associated with successful myocardial reperfusion during thrombolytic therapy, but they have been also suggested to be a marker of large infarct size and worse prognosis. Ischemic postconditioning (PostC) has been shown to reduce the incidence of reperfusion arrhythmias. However, the mechanisms involved in the antiarrhythmic effects of ischemic PostC are not well known. The aims of this study were (1) to analyze the electrophysiologycal effects of ischemic PostC on passive myocardial electrical properties, as a surrogate of gap junctional communication, in isolated rat hearts, and (2) to assess the involvement of connexin 43 (Cx43) in these effects, using isolated hearts from wild-type mice and from mice devoid of connexin 43. Methods and results: Isolated rat hearts were submitted to 20 min of global ischemia followed by 25 min of reperfusion. Myocardial electrical impedance (tissue resistivity and phase angle) was assessed using a four-electrode probe, placed in the left ventricular free wall, at 7 kHz. Global ischemia induced a marked rise in resistivity and a decrease in phase angle (p≤0.05). Ischemic PostC (6 cycles of 10 seconds of reperfusion/ischemia, n=7), applied at the onset of reperfusion, slowed and delayed, by about 4 min, recovery of tissue resistivity as compared with recovery in control hearts. To analyze the involvement of Cx43 in these changes, isolated hearts from two Cx43-defficient mice (Cx43KI32 mice, in which the coding region for Cx43 is replaced by that of Cx32, and a inducible knock-out model, in which a marked reduction in Cx43 expression is achieved after 4-hydroxytamoxifen administration) were submitted to 30 min of global ischemia followed by reperfusion. Hearts from wild-type animals and from both homozygous Cx43KI32 mice (n=6-8) and Cx43Cre-ER(T)/fl mice (n=7-8), were protected against infarction by ischemic PostC (6 cycles of 10 seconds of reperfusion/ischemia). Similar to findings in isolated rat and mice wild-type hearts, ischemic PostC still delayed recovery of tissue resisitvity (about 3 min) in hearts from Cx43-defficient animals. Conclusions: Ischemic PostC delays recovery of tissue resistivity during reperfusion, but this effect is indepenent of Cx43 expression.. The mechanisms of the antiarrhythmic effect of ischemic postconditioning remain elusive.

Bioelectrical impedance analysis; a new method to evaluate lymphoedema, fluid status, and tissue damage after gynaecological surgery - A systematic review

The influence of ultraviolet (UV) ageing on complex modulus, phase angle and low-temperature fatigue factor was studied by dynamic shear rheometer test. The ageing degree of the bitumen was evaluated by the rheological parameters. The results show that UV ageing causes an increase in complex modulus and fatigue factor, as well as a decrease in phase angle, indicating that the bitumen becomes more elastic after UV ageing process and is apt to crack at low temperatures. Different bitumen exhibits diverse changes in the rheological parameters after UV ageing, which is much dependent on the sources of bitumen.

Background and aimsChild overweight and obesity has increased globally every region of the world. Based on the evidence of 2014, 19.9% of children in the Russian Federation are overweight and...

Cross-linking agent has recently been introduced into asphalt rubber (AR) as an additive, mainly with the goal of improving workability of this material. This study was performed to investigate the high temperature properties of AR when combined with Trans-polyoctenamer (TOR) at 0%, 3% and 6% of the weight of crumb rubber. High temperature properties were evaluated using the Dynamic Shear Rheometer (DSR) and the separation properties by Tubes in conjunction with DSR method. Results showed that (1) addition of TOR in the AR can effectively increase the G*/sin(delta) of the binders in both the original state as well as RTFO residue, with up to a 20% increase in G*/sin(delta) found for a dose of 6% TOR; (2) addition of TOR into AR can also decrease the phase angle of the binders in the original state as well as RTFO residue; up to a 1.8% decrease in phase angle was found for a dose of 6% TOR; (3) addition of the TOR can significantly decrease the separation of AR binders, as evaluated by DSR testing. An absolute difference in failure temperatures of 20% less than the control was found for a dose of 3% TOR in PG 67-22 asphalt. The influence of TOR on the separation of AR made with PG 64-22 asphalt was less than that of AR made with PG 67-22 asphalt.

The oscillatory indentation has become an attractive approach to characterizing the viscoelastic properties of soft biological solids. However, the influences of surface tension on oscillatory responses are ignored, which might lead to an inaccurate measurement of mechanical properties. In this work, the influences of surface tension on spherical oscillatory indentation for viscoelastic materials are investigated through the finite element method. The viscoelasticity of solids is characterized by the standard linear solid model and a sinusoidal displacement is applied as the excitation signal. During an entire cycle at the steady-state of oscillation, both the average value of contact radius and the dissipated energy decrease due to the presence of surface tension. For the oscillatory responses at various frequencies, the existence of surface tension results in an increase in average force but a decrease in phase angle. The force amplitude at low frequencies becomes higher when surface tension is considered. For the evaluation of the complex modulus, neglecting the surface tension would lead to a significant overestimation of storage modulus at low frequencies and an obvious underestimation of loss modulus when the normalized frequency approaches one. Our results provide a comprehensive understanding of the effects of surface tension on the mechanical responses of oscillation and the determination of viscoelastic properties through oscillatory indentation.

The TEAGE ageing method for asphalt mixtures

Bioelectrical impedance vector analysis (BIVA) is a method used to estimate variation in body hydration. We assessed the potential of BIVA for monitoring daily body hydration fluctuations in nine healthy, normally active males under matching normoxic (NX) and hypobaric hypoxic (HH) experimental conditions. Furthermore, we aimed to investigate whether changes in BIVA may correspond with the development of acute mountain sickness (AMS). Subjects were exposed in a hypobaric chamber to both NX (corresponding to an altitude of 262 m) and HH conditions corresponding to an altitude of 3500 m during two four-day sojourns within which food, water intake and physical activity were controlled. Bioimpedance and body weight measurements were performed three times a day and medical symptoms were assessed every morning using the Lake Louise score (LLS). Total body water (TBW) was also assessed on the last day of both sojourns using the deuterium dilution technique. We detected circadian changes in vector length, indicating circadian body water variations that did not differ between NX and HH conditions (ANOVA effects: time: p = 0.018, eta2 = 0.149; interaction: p = 0.214, eta2 = 0.083; condition: p = 0.920, eta2 = 0.001). Even though none of the subjects developed AMS, four subjects showed clinical symptoms according to the LLS during the first 24 hours of HH conditions. These subjects showed a pronounced (Cohen’s d: 1.09), yet not statistically significant (p = 0.206) decrease in phase angle 6 hours after exposure, which may indicate fluid shift from the intracellular to the extracellular compartment. At the end of each sojourn, vector length correlated with deuterium dilution TBW “gold standard” measurements (linear regression: NX: p = 0.002 and r2 = 0.756, HH: p < 0.001 and r2 = 0.84). BIVA can be considered a valuable method for monitoring body hydration changes at altitude. Whether such changes are related to the development of clinical symptoms associated with AMS, as indicated in the present investigation, must be confirmed in future studies.

This article assesses the impact of ageing on the properties of asphalt concrete (AC) by combining experiments and numerical simulations. Rheological tests were performed at four thermal ageing durations (0, 3, 6 and 9 days). The results show an increase in the complex modulus and a decrease in phase angle with ageing time. For each ageing time, semi-circular bending tests were carried out under two loading rates (1 and 5 mm/min) and three temperatures (\(-20\), 0 and 20 \({}^{\circ }\)C). The results shown an increase of the peak load when the loading rate increases for each thermal ageing time and temperature. No meaningful variation of the peak load with respect to the ageing time was observed at low temperatures. However, it was found that at \(20\,{}^{\circ }\)C, the peak load increases with ageing duration. A finite element modelling was implemented, coupling viscoelastic behaviour and crack growth criterion. The results show a similarity between numerical and experimental results.

Both overhydration and comorbidity predict mortality in end-stage kidney failure (ESKF) but it is not clear whether these are independent of one another. We undertook a systematic review of studies reporting outcomes in adult dialysis patients in which comorbidity and overhydration, quantified by whole body bioimpedance (BI), were reported. PubMed, EMBASE, PsychInfo and the Cochrane trial database were searched (1990–2017). Independent reviewers appraised studies including methodological quality (assessed using QUIPS). Primary outcome was mortality, with secondary outcomes including hospitalisation and cardiovascular events. Of 4028 citations identified, 46 matched inclusion criteria (42 cohorts; 60790 patients; 8187 deaths; 95% haemodialysis/5% peritoneal dialysis). BI measures included phase angle/BI vector (41%), overhydration index (39%) and extra:intracellular water ratio (20%). 38 of 42 cohorts had multivariable survival analyses (MVSA) adjusting for age (92%), gender (66%), diabetes (63%), albumin (58%), inflammation (CRP/IL6–37%), non-BI nutritional markers (24%) and echocardiographic data (8%). BI-defined overhydration (BI-OH) independently predicted mortality in 32 observational cohorts. Meta-analysis revealed overhydration >15% (HR 2.28, 95% CI 1.56–3.34, P < 0.001) and a 1-degree decrease in phase angle (HR 1.74, 95% CI 1.37–2.21, P < 0.001) predicted mortality. BI-OH predicts mortality in dialysis patients independent of the influence of comorbidity.

Archaeal Tetraether Free Standing Lipid Membranes in a PDMS and PCB based Fluidic Platform

A prospective study on the radiation therapy associated changes in body weight and bioelectrical standardized phase angle

Multi-functional hybrid coatings having both anti-corrosion and scratchresistance were prepared from modified silica nanoparticles and functionalacrylates. To improve the dispersion properties of silica nanoparticles in theorganic/inorganic hybrid coatings, the surface of the nanoparticles was modified withγ-methacryloxypropyltrimethoxysilane. The coating solution could be prepared by mixingmodified silica nanoparticles, tetrasiloxane acrylate, di-acrylate monomer containing ananti-corrosion functional group, acrylic acid, and an initiator in a solvent. The mixture wasthen dip-coated on iron substrates and finally polymerized by ultraviolet (UV) irradiation.Corrosion and scratch resistance of the coated iron was evaluated by electrochemicalimpedance spectroscopy (EIS) and a pencil hardness test, respectively. Fromthe EIS results, the coatings with tetrasiloxane acrylate and di-acrylate did notshow any decrease in impedance or phase angle, even after 50 days’ exposure to0.1 M NaCl electrolyte, whereas the conventional acrylate coatings started to failafter only 24 h. A hybrid coating containing the amine–quinone functional groupexhibited excellent corrosion protection properties with 4–5H pencil hardness.

In this study, the influence of some inorganic nanoparticles on the properties of bitumen binder was investigated. Three types of particles at nanometer level, calcium carbonate powder, graphite and carbon black, were introduced to modify bitumen respectively. The modified binders were prepared using a laboratory high-shear mixer. A dynamic shear rheometer (DSR) was adopted to characterize the properties of modified binders, including their rheological parameters and dynamic viscosity, over a certain range sweeps of temperatures, frequencies and shear rates. It was found that the addition of the nanoparticles increased the binder’s elasticity at low temperature which might negatively influence its resistance to crack. However the decrease of phase angle at high temperature might improve its deformation resistance. The shear rate dependence of dynamic viscosity for the binders depended on the type of nanoparticle. The research results indicated that the addition of nanoparticles to bitumen binder can change its physical properties to some extent and its potential should be researched further.

Traditional modified asphalt has limitations in anti-aging, fatigue resistance, and environmental protection performance. In this study, a new type of graphene/rubber powder composite modified asphalt (CMA) is prepared to synergistically enhance the anti-aging and anti-fatigue properties. CMA is prepared by melting and co-mixing at 180 ℃ and high-speed shearing at 5000 rpm. The performance is evaluated using scanning electron microscopy (SEM), dynamic shear rheometer (DSR), and Fourier transform infrared spectroscopy (FTIR) in the experiment. The results showed that the modified asphalt showed excellent anti-aging performance. After 60 hours of aging, the phase angle only decreased from 60.1° to 56.4°, while the phase angle of the unmodified matrix asphalt group decreased from 50.1° to 40.3°. The smaller the decrease of phase angle, the better the aging resistance of asphalt. The anti-aging performance of the modified asphalt was about 62.2% higher than that of the base asphalt. The aging index of carbonyl and sulfoxide groups significantly decreased (0.035 and 0.037, respectively). The anti-fatigue performance has also been significantly improved, with the CMA reaching 113,652 cycles at 2.5 % strain, an increase of 73.98 % compared to the matrix asphalt group. This mechanism was attributed to the layered barrier structure of graphene (delaying oxidation) and the sulfur crosslinked network of rubber powder (absorbing thermal stress). At the same time, the rigid structure of graphene combined with the flexibility of rubber formed an interlocking network that resisted crack propagation and could suppress the propagation of asphalt microcracks. Such a structure can effectively improve the anti-aging and anti-fatigue performance of modified asphalt, providing a promising solution for the design of long-life pavement, especially in heavy traffic and extreme climate environment.