Increase In Phase Angle Research Articles

P5407Body-composition analysis of patients with acute heart failure - preliminary results from the SCALE HF trial

Abstract Background Guidance for intensified diuretic therapy in acute heart failure (AHF) is mainly based on body weight measurement, frequently leading to a short episode of dehydration with kidney failure after recompensation. In addition, patients often present immobilized due to severe health issues making weight measurement stressful. Purpose Bioelectrical impedance analysis (BIA) may be a more direct approach to guide intensified diuretic therapy analysing patient's body composition. We hypothesized that patient's weight loss during therapy correlates with loss of body water measured by BIA. Therefore, we tested if this method could be an alternative to daily weight measurement. Methods We conducted an observational, single-centre study to evaluate and monitor body composition of patients hospitalised with AHF, adjudicated according to current ESC/HFA guidelines by a cardiologist. We used an eight-electrode, segmental, multi-frequency body composition analyser, previously validated against air displacement plethysmography, whole body MRI, deuterium and sodium bromide dilution. We investigated patients until hospital discharge or latest one day after ending intensified diuretic therapy. Disease specific properties, BIA and weight measurement were assessed daily. Furthermore, we investigated BIA raw data. Results 390 BIA were applied on 76 patients (47 men; 29 women; mean age 76±11 years; mean weight 75.6±15.7 kg). 34 patients presented with global, 27 with left-heart, 8 with right-heart and 7 with not specified AHF. 44 patients presented with pleural effusion. Pearson correlations showed that total body water (r=0.737, p≤0.001) and extracellular water (r=0.69, p≤0.001) correlated each with total body weight. Changes in total body water accurately (within a range of ± 1kg) reflected changes in total body weight in 40.28% of the patients and changes in extracellular water showed a similarly accurate reflection of total body weight change in 68.06% of the patients. BIA raw-data analysis showed significant changes using Wilcoxon test between measurements at the beginning of intensified diuretic therapy and at its end. We found a significant increase of resistance (mean from 334.6±67.5 to 362.8±69.5 Ohm/m; p=0.021) and reactance (mean from 21.3±7.1 to 24.1±6.2 Ohm/m; p=0.009) standardized to patients height and a non-significant increase of phase angle (mean from 3.6±0.9 to 3.8±0.8 °; p=0.149) during hospitalisation. Conclusion BIA is able to estimate changes in total body weight by analysing changes in extracellular body water in patients under intensified diuretic therapy and raw data analysis seems even more accurate and promising. This data derive from a heterogeneous AHF patient group, needing further investigation. Once validated, wearable BIA connected to an automated device monitoring system would enable an easy to use diuretic therapy monitoring for impaired patients or outpatients and could help reducing care efforts.

Evaluating the Effects of High RAP Content and Rejuvenating Agents on Fatigue Performance of Fine Aggregate Matrix through DMA Flexural Bending Test.

High percentage reclaimed asphalt pavement (RAP) is prevailing in pavement engineering for its advantages in sustainability and environmental friendliness, however, its fatigue resistance remains a major concern. Fine aggregate matrix (FAM) is a crucial part in the fatigue resistance of asphalt mixtures with high RAP content. Hence, the linear amplitude sweep (LAS) test of FAM has been developed to study the fatigue resistance of asphalt mixtures. However, the torsional loading mode of the LAS test with a dynamic shear rheometer (DSR) is a limitation to simulate traffic load. In this paper, an alternative LAS test for FAM with high RAP content was proposed. Beam FAM specimens were tested using a dual-cantilever flexural loading fixture in a dynamic mechanical analyzer (DMA). To investigate the influence of RAP content and the rejuvenating agent (RA), four kinds of FAM mixes were tested with this method to study their fatigue resistance. The test results suggested that the repeatability of this alternative approach was reliable. A fatigue failure criterion based on maximum was defined. Then, fatigue life prediction models based on viscoelastic continuum damage (VECD) analysis were established according to the LAS test results and validated by a strain-controlled time sweep (TS) test. It turned out that as RAP content increased, the modulus of FAM would be significantly raised, accompanied with a drop in the phase angle. The fatigue life of FAM would be greatly shortened when the RAP binder replacement rate reached 50%. Adding RA could considerably improve the dynamic properties of FAM mixes with high RAP content, resulting in a decrease in modulus, increase in phase angle and elongating fatigue life, but could not recover to the level of virgin binder.

Phase angle and metabolic equivalents as predictors of frailty transitions in advanced age.

The aim of this prospective study was to investigate whether two cellular and metabolic health indices, phase angle (PhA) and metabolic equivalents (METs), can predict changes in frailty states in fit community-dwelling older people. A sample of 118 individuals aged ≥65 years who attended a twice-weekly mild fitness program of aerobic and/or resistance exercises was enrolled in the study. At baseline and after three years, individuals underwent a clinical examination, biochemical determinations, bioelectrical impedance analysis, body composition assessment with dual energy X-ray absorptiometry, physical performance tests, and frailty and sarcopenia assessment. In 78 participants was executed indirect calorimetry, too. Based on frailty transitions during the follow-up between non-frailty, pre-frailty and frailty, participants were categorized as improved, stable (non-frail or pre-frail), and worsened or remaining frail. The chances to experience different frailty changes by baseline PhA and METs were explored through multinomial regression analysis and expressed as odds ratios (OR) and 95% Confidence intervals (95%CI). During the follow-up, 8 participants improved in frailty status, 84 were stable and 26 worsened or remained frail. For each one-unit increase in PhA, the odds of improving in frailty increased by 4.53 times (95%CI:1.18-17.46); while for each one-unit increase in METs, the odds of worsening in frailty decreased by 65% (95%CI:0.16-0.79). PhA and METs may be indirect measures of functional reserve, with lower values being potential biomarkers of evolving frailty.

Laboratory evaluation of performance of porous ultra-thin overlay

Porous ultra-thin overlay (PUTO) is a new type of pavement maintenance technology which combines skid resistance and drainage functions. The engineering properties of two high-viscosity modifier (type I and type II) modified asphalt and two gradations (coarse and fine) of asphalt mixtures, including high- temperature rutting resistance, low-temperature crack resistance and moisture sensitivity, were investigated. The dynamic modulus and phase angle of the asphalt mixture under dynamic loading conditions were then analyzed and master curves of dynamic modulus and phase angle were established. Finally, the drainage and skid resistance of the PUTO were evaluated. The results show that the dynamic stability (DS) of the asphalt mixture with coarse gradation is larger than that of the asphalt mixture with fine gradation. The bending strain of four asphalt mixtures shows small differences, the maximum value being 364 με larger than the minimum value, and they all meet the requirements of the specification. The excellent adhesion of the high-viscosity asphalt binder enhances the anti-stripping ability between asphalt and aggregates, enabling the mixture to resist water damage well. As the temperature increases or the load frequency decreases, the dynamic modulus decreases and the phase angle increases. By establishing the master curves of dynamic modulus and phase angle, it can be concluded that gradation as the main skeleton of PUTO asphalt mixture plays a major role in its performance and strength. Under the same rainfall conditions, the asphalt mixture with coarse gradation can transfer water on the pavement surface to the outside more quickly. Coarse gradation is beneficial for the enhancement of the macroscopic structure and improvement of the skid resistance of pavement surface.

Preparation and Electrochemical Characterization of Concrete Containing Microencapsulated Calcium Nitrate Corrosion Inhibitor

We present the preparation and inhibition behavior of rebar in the presence of calcium nitrate (CN)-containing microcapsules with concentrations of 0.50, 2.00, and 5.00 wt.% in concrete. From both open circuit potential (OCP) and electrochemical impedance spectroscopy spectra, it was found that an addition of microcapsules containing CN corrosion inhibitor into concrete beams successfully repassivated or maintained the passivity of the rebar when the concrete was cracked. This corrosion inhibitor repassivated the rebar by forming a passive layer on the rebar surface under the crack. This repassivation process was evident by an increase of OCP values to more positive values or by stable OCP values at around -100 mV vs SCE. An increase in phase angle after corrosion activation for the sample with 2.00 wt.% microcapsule clearly showed this repassivation process. The optimum concentration for maintaining the passivity on rebar in the cracked concrete was found to be 5.00 wt.%.

Changes in bioimpedance analysis components before and after hemodialysis.

BackgroundThis study compared nutritional parameters in hemodialysis (HD) subjects and controls using bioimpedance analysis (BIA) and investigated how BIA components changed before and after HD.MethodsThis cross-sectional study included 147 subjects on maintenance HD from two hospitals and 298 propensity score-matched controls from one healthcare center. BIA was performed pre- and post-HD at mid-week dialysis sessions.ResultsExtracellular water/total body water (ECW/TBW) and waist-hip ratio were higher in the HD patients; the other variables were higher in the control group. The cardiothoracic ratio correlated best with overhydration (r = 0.425, P < 0.01) in HD subjects. Blood pressure, hemoglobin, creatinine, and uric acid positively correlated with the lean tissue index in controls; however, most of these nutritional markers did not show significant correlations in HD subjects. Normal hydrated weight was predicted to be higher in the pre-HD than post-HD measurements. Predicted ultrafiltration (UF) volume difference based on pre- and post-HD ECW/TBW and measured UF volume difference showed a close correlation (r2 = 0.924, P < 0.01). Remarkably, the leg phase angle increased in the post-HD period.ConclusionThe estimated normal hydrated weight using ECW/TBW can be a good marker for determining dry weight. HD subjects had higher ECW/TBW but most nutritional indices were inferior to those of controls. It was possible to predict UF volume differences using BIA, but the post-HD increase in leg phase angle, a nutritional marker, must be interpreted with caution.

Laboratory evaluation on residue in castor oil production as rejuvenator for aged paving asphalt binder

In this study, residue in castor oil production is evaluated as a rejuvenator for aged paving asphalt binder. Different contents of the bio-based rejuvenator, ranging from 0% to 50%, were added to PAV aged binder to prepare samples. DSR tests and BBR tests were carried out to characterize rheological properties of rejuvenated binder. Furthermore, continuous PG grading temperatures were determined from DSR and BBR test data. Test results and data analyses show a notable decrease in complex modulus and an increase in phase angle with increasing rejuvenator content, indicating restoration in viscoelastic properties of the binder. The binder with 30% rejuvenator reaches a level similar to original binder in rutting parameter. The binder with 20% rejuvenator reaches a level similar to original binder in control thermal cracking parameter. The grading temperatures show that all the upper, lower, and intermediate grading temperatures decrease with increasing rejuvenator content, indicating a negative effect on rutting resistance, and positive effects on thermal and fatigue cracking resistances of the binder. The serviceability temperature shows that the gaining in low temperature behavior is more significant than the loss in high temperature behavior, indicating an improving effect of the rejuvenator on temperature susceptibility of the rejuvenated binder.

Biaxial fatigue behavior of gradient structural purity titanium under in-phase and out-of-phase loading

Biaxial fatigue behavior of gradient structural pure titanium fabricated by surface nanocrystallization technique (SNC) was investigated under in-phase (IP) and out-of-phase (OP) loading. The fatigue life of SNC Ti under 90° OP loading is shorter than that under IP loading, which is attributed to the fact that both the maximum shear stress and maximum normal stress under 90° OP loading are larger than that under IP loading at the same cyclic equivalent stress amplitude. Under IP loading, the fatigue life increases as the stress ratio increases; Under OP loading, the fatigue life decreases as the phase angle increases. The fatigue microcracks nucleate and propagate preferentially along shear bands (SBs) under both IP and OP loading. The growing direction of the microcracks and macrocrack were determined experimentally and predicted using the critical plane approaches. The results indicate that the measured directions of macrocrack under IP and OP loading are closely consistent with the theoretical prediction. After biaxial fatigue tests, the stress-induced nanograins growth was observed on the top surface. As a result of rotation of maixmum shear stress plane uner 90° OP loading. The degree of nanograins growth under 90° OP loading is larger than that under IP loading. The corresponding dislocation substructure in coarse grained region changes from the parallel dislocation lines under IP loading to the dislocation tangles under 90° OP loading.

Correlations between resistance training-induced changes on phase angle and biochemical markers in older women.

The main purpose of this study was to investigate the effects of 12weeks of resistance training (RT) on phase angle (PhA), inflammatory and oxidative stress biomarkers, and to evaluate whether these RT-induced adaptations are related to PhA changes. Fifty-one older women (70.6±5.1years; 26.9±4.2kg/m2 ) were randomly allocated into a training group (TG) that performed 12-week RT or a nonexercising control group (CG). The PhA (Xitron), body composition (DXA), and blood sample measurements (after a 12hours fast) were performed before and after the intervention. The TG showed a significant (P<.05) increase in PhA (TG: +7.4±5.9% vs CG: -3.6±8.8%), and interleukin-10 (IL-10; TG: +51.8±71.1% vs CG: -46.6±38.0%), and a decrease in tumor necrosis factor alpha (TNF-α; TG: -15.2±11.1% vs CG: +6.9±17.7%), interleukin-6 (IL-6; TG: -17.9±17.8% vs CG: +6.1±24.8%), and C-reactive protein (CRP; TG: -24.1±19.9% vs CG: +43.8±31.1%). Moreover, TG upregulated catalase (TG: +11.4±15.0% vs CG: -6.7±10.2%). Changes in TNF-α (r=-.71), CRP (r=-.65), lower advanced oxidation protein products (r=-.55), and catalase (r=+.73) after RT were correlated with changes in PhA (P<.05). These results suggest that RT improves PhA, inflammatory and oxidative stress biomarkers, and the changes in inflammatory and oxidative damage markers are correlated with changes in PhA.

Shear and foundation effects on crack root rotation and mode-mixity in moment- and force-loaded single cantilever beam sandwich specimen

Foundation effects play a crucial role in sandwich fracture specimens with a soft core. Accurate estimation of deformation characteristics at the crack front is vital in understanding compliance, energy release rate and mode-mixity in fracture test specimens. Beam on elastic foundation analysis of moment- and force-loaded single cantilever beam sandwich fracture specimens is presented here. In addition, finite element analysis of the single cantilever beam specimen is conducted to determine displacements, rotations, energy release rate and mode-mixity. Based on finite element analysis, a foundation modulus is proposed that closely agrees with the numerical compliance and energy release rate results for all cases considered. An analytical expression for crack root rotation of the loaded upper face sheet provides consistent results for both loading configurations. For the force-loaded single cantilever beam specimen (in contrast to the moment-loaded case), it was found that the crack length normalized energy release rate and the mode-mixity phase angle increase strongly as the crack length decreases, a result of increased dominance of shear loading.

Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations

We present reflectance and polarization phase curve measurements of highly reflective planetary regolith analogues having physical characteristics expected on atmosphereless solar system bodies (ASSBs) such as a eucritic asteroids or icy satellites. We used a goniometric photopolarimeter (GPP) of novel design to study thirteen well-sorted particle size fractions of aluminum oxide (Al2O3). The sample suite included particle sizes larger than, approximately equal to, and smaller than the wavelength of the incident monochromatic radiation (λ = 635 nm). The observed phase angle, α, was 0.056 o < α < 15°. These Al2O3 particulate samples have very high normal reflectance (> ∼95%). The incident radiation has a very high probability of being multiply scattered before being backscattered toward the incident direction or ultimately absorbed. The five smallest particle sizes exhibited extremely high void space (> ∼95%).The reflectance phase curves for all particle size fractions show a pronounced non-linear reflectance increase with decreasing phase angle at α∼ < 3°. Our earlier studies suggest that the cause of this non-linear reflectance increase is constructive interference of counter-propagating waves in the medium by coherent backscattering (CB), a photonic analog of Anderson localization of electrons in solid state media.The polarization phase curves for particle size fractions with size parameter (particle radius/wavelength) r/λ < ∼1, show that the linear polarization rapidly decreases as α increases from 0°; it reaches a minimum near α = ∼2°. Longward of ∼2°, the negative polarization decreases as phase angle increases, becoming positive between 12° and at least 15°, (probably ∼20°) depending on particle size. For size parameters r/λ > ∼1 we detect no polarization.This polarization behavior is distinct from that observed in low albedo solar system objects such as the Moon and asteroids and for absorbing materials in the laboratory. We suggest this behavior arises because photons that are backscattered have a high probability of having interacted with two or more particles, thus giving rise to the CB process.These results may explain the unusual negative polarization behavior observed near small phase angles reported for several decades on highly reflective ASSBs such as the asteroids 44 Nysa, 64 Angelina and the Galilean satellites Io, Europa and Ganymede. Our results suggest these ASSB regoliths scatter electromagnetic radiation as if they were extremely fine grained with void space > ∼95%, and grain sizes of the order < = λ. This portends consequences for efforts to deploy landers on high ASSBs such as Europa. These results are also germane to the field of terrestrial geo-engineering, particularly to suggestions that earth's radiation balance can be modified by injecting Al2O3 particulates into the stratosphere thereby offsetting the effect of anthropogenic greenhouse gas emissions.The GPP used in this study was modified from our previous design so that the sample is presented with light that is alternatingly polarized perpendicular to and parallel to the scattering plane. There are no analyzers before the detector. This optical arrangement, following the Helmholtz Reciprocity Principle (HRP), produces a physically identical result to the traditional laboratory reflectance polarization measurements in which the incident light is unpolarized and the analyzers are placed before the detector. The results are identical in samples measured by both methods. We believe that ours is the first experimental demonstration of the HRP for polarized light, first proposed by Helmholtz in 1856.

Nonlinearity of bituminous mixtures

This paper presents an experimental characterization of the strain dependency of the complex modulus of bituminous mixtures for strain amplitude levels lower than about $110~\upmu\mbox{m}/\mbox{m}$ . A series of strain amplitude sweep tests are performed at different temperatures (8, 10, 12 and 14°C) and frequencies (0.3, 1, 3 and 10 Hz), during which complex modulus is monitored. For each combination of temperature and frequency, four maximum strain amplitudes are targeted (50, 75, 100 and $110~\upmu\mbox{m}/\mbox{m}$ ). For each of them, two series of 50 loading cycles are applied, respectively at decreasing and increasing strain amplitudes. Before each decreasing strain sweep and after each increasing strain sweep, 5 cycles are performed at constant maximum targeted strain amplitude. Experimental results show that the behavior of the studied material is strain dependent. The norm of the complex modulus decreases and phase angle increases with strain amplitude. Results are presented in Black and Cole–Cole plots, where characteristic directions of nonlinearity can be identified. Both the effects of nonlinearity in terms of the complex modulus variation and of the direction of nonlinearity in Black space seem to validate the time–temperature superposition principle with the same shift factors as for linear viscoelasticity. The comparison between results obtained during increasing and decreasing strain sweeps suggests the existence of another phenomenon occurring during cyclic loading, which appears to systematically induce a decrease of the norm of the complex modulus and an increase of the phase angle, regardless of the type of the strain sweep (increasing or decreasing).

Viscoelastic properties of sweet potato complementary porridges as influenced by endogenous amylases.

Sweet potato (Ipomoea batatas L.) roots contain amylolytic enzymes, which hydrolyze starch thus having the potential to affect the viscosity of sweet potato porridges provided the appropriate working conditions for the enzymes are attained. In this study, the effect of sweet potato variety, postharvest handling conditions, freshly harvested and room/ambient stored roots (3 weeks), and slurry solids content on the viscoelastic properties of complementary porridges prepared using amylase enzyme activation technique were investigated. Five temperatures (55°C, 65°C, 70°C, 75°C, and 80°C) were used to activate sweet potato amylases and the optimum temperature was found to be 75°C. Stored sweet potato roots had higher soluble solids (⁰Brix) content in the pastes compared to fresh roots. In all samples, activation of amylases at 75°C caused changes in the viscoelastic parameters: phase angle (tan δ) and complex viscosity (η*). Postharvest handling conditions and slurry solids content significantly affected the viscoelastic properties of the porridges with flours from stored roots yielding viscous (liquid‐like) porridges and fresh roots producing elastic (solid‐like) porridges. Increase in slurry solids content caused reduction in the phase angle values and increase in the viscosity of the sweet potato porridges. The viscosity of the porridges decreased with storage of sweet potato roots. These results provide a possibility for exploiting sweet potato endogenous amylases in the preparation of complementary porridges with both drinkable viscosities and appropriate energy and nutrient densities for children with varying energy needs.

Phase Angle Predicts Arterial Stiffness and Vascular Calcification in Peritoneal Dialysis Patients.

Fluid overload (FO) is frequently present in peritoneal dialysis (PD) patients and is associated with markers of malnutrition, inflammation, and atherosclerosis/calcification (MIAC) syndrome. We examined the relationships in stable PD patients between phase angle (PhA) and the spectrum of uremic vasculopathy including vascular calcification and arterial stiffness and between PhA and changes in serum fetuin-A levels. Sixty-one stable adult PD patients were evaluated in a cross-sectional study (ST1). Phase angle was measured by multifrequency bioimpedance analysis (InbodyS10, Biospace, Korea) at 50 kHz. Augmentation index (AI), a surrogate marker of arterial stiffness, was assessed by digital pulse amplitude tonometry (Endo PAT, Itamar Medical, Caesarea, Israel). Vascular calcification was assessed by simplified calcification score (SCS). Serum fetuin-A levels were measured by ELISA (Thermo scientific; Waltham, MA, USA). Serum albumin was used as a nutritional marker, and serum C-reactive protein (CRP) was used as an inflammatory marker. The same assessments were carried out longitudinally (ST2) in the first 33 patients who completed 1 year of evaluation in ST1. In ST1, patients with PhA < 6° had higher CRP levels, AI, and SCS and lower serum albumin and fetuin-A levels, in comparison with patients with PhA ≥ 6°. In addition, PhA was a predictor of both AI (β = -0.351, p = 0.023) and SCS ≥ 3 (EXP (B) = 0.243, p = 0.005). In ST2, the increase of PhA over time was associated with decreases in both AI (r = -0.378, p = 0.042) and CRP levels (r = -0.426, p = 0.021), as well as with the increase in serum fetuin-A levels (r = 0.411, p = 0.030). Phase angle predicts both arterial stiffness and vascular calcification in stable PD patients.

Potential of used frying oil in paving material: solution to environmental pollution problem

The improper disposal of used frying oil (UFO) presents numerous ecological, environmental and municipal problems. Of great concern is the resultant blockage of municipal drainage systems and water treatment facilities, harm to wildlife when they become coated in it and detriment to aquatic life and ecosystems due to the depletion of the oxygen content in water bodies such as rivers and lakes that have become contaminated. Statistics show that in Trinidad and Tobago, in excess of one million liters of used cooking oil is collected annually from various restaurant chains. This paper investigated the potential of using UFO as a performance enhancing additive for road paving applications utilizing Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB) as a mitigation strategy for improper UFO disposal. Modified blends containing various additions of UFO (2–10% wt) were prepared for the TLA and TPB asphaltic binders. Results demonstrated in terms of stiffness, increasing the dosage of UFO in TLA and TPB base binders resulted in a gradual decrease in stiffness (G* value decreased). In terms of elasticity, increasing the dosage of the UFO additive in TLA resulted in a general decrease in the elasticity of the blends indicated by an increase in phase angle or phase lag (δ). Increasing dosages of the UFO additive in TPB resulted in a significant decrease in δ where the most elastic blend was at the 6% UFO level. TLA and UFO-TLA modified blends exhibited significantly lower values of δ and higher values of G* confirming the superiority of the TLA material. Incorporation of the UFO in the blends led to a decrease in the rutting resistance and increase in the fatigue cracking resistance (decrease in G*/sinδ and G*sinδ, respectively). This study highlighted the potential for the reuse of UFO as an asphalt modifier capable of producing customized UFO modified asphaltic blends for special applications and confirms its feasibility as an environmentally attractive means of reusing the waste/hazardous UFO material locally.

Ultrasonic degradation kinetics and rheological profiles of a food polysaccharide (konjac glucomannan) in water

This study was carried out to evaluate the effects of power ultrasound (US) on the molecular weight and rheological properties of a food polysaccharide, konjac glucomannan (KGM). Upon the exposure of KGM solution (1% w/v in water) to US at a relatively high power intensity (50 W/cm2), the apparent viscosity decreased rapidly from about 50 Pa s to a negligible level within 10–20 min. The intrinsic viscosity ([η]) of KGM solution decreased gradually during the US exposure with a time course closely fitted to the first-order polymer degradation kinetics (random chain scission). The US treatment also caused a significant reduction of particle size (Zavg) of KGM aggregates and changes in the rheological properties including the decrease of storage modulus (G′) and loss modulus (G″), and the increase in phase angle (tan δ = G″/G′). Nevertheless, no change in primary structure was detected by Fourier transformation infrared (FT-IR) analysis. The results suggested that high intensity US was an effective means for KGM degradation without significant structural destruction.

Body composition analysis and adipocytokine concentrations in haemodialysis patients: Abdominal fat gain as an added cardiovascular risk factor. Abdominal fat gain and cardiovascular risk

IntroductionAbdominal fat and its increment over time in particular has become a cardiovascular risk factor in uraemic patients. ObjectivesTo analyse changes in abdominal fat in haemodialysis patients over one year and study their possible correlation with the variation in adipocytokine serum levels. As a secondary objective, we tried to validate the data obtained by bioelectrical impedance analysis (BIA) with data obtained by dual X-ray absorptiometry (DXA). Material and methodsA prospective one-year study was performed in 18 patients on haemodialysis (HD). In each patient, body composition by BIA and DXA was estimated at baseline and after one year. Several adipocytokine and biochemical parameters were determined. ResultsA significant increase in phase angle [4.8° (4.1–5.6) vs. 5.2° (4.4–5.8), p<0.05], BIA intracellular water [48.3% (43.1–52.3) vs. 50.3% (45.7–53.4), p<0.05] and the ratio between the percentage of android/gynecoid (A/G) distribution of fat measured by DXA [1.00 (0.80–1.26) vs. 1.02 (0.91–1.30), p<0.05] was observed. A statistically significant relationship between leptin and adiponectin concentrations and the percentage of fat mass measured by BIA, as well as the abdominal fat percentage estimated by DXA, was found (p<0.01). ConclusionHD patients exhibit a gain in fat mass over time, especially in the abdomen, evidenced by an increased A/G ratio. These findings might explain the increased cardiovascular risk in these patients.

Hypertrophy-type Resistance Training Improves Phase Angle in Young Adult Men and Women.

The main purpose of the present study was to investigate the effect of a hypertrophy-type resistance training protocol on phase angle, an indicator of cellular integrity, in young adult men and women. 28 men (22.2±4.3 years, 67.8±9.0 kg and 174.2±6.8 cm) and 31 women (23.2±4.1 years, 58.7±12.1 kg and 162.7±6.4 cm) underwent a progressive RT for 16 weeks (2 phases, 8 weeks each), 3 times per week, consisting of 10 to 12 whole body exercises with 3 sets of 8-12 repetitions maximum. Phase angle, resistance, reactance and total body water (intra and extracellular water compartments) were assessed by bioimpedance spectroscopy (Xitron 4200 Bioimpedance Spectrum Analyzer). Total body water, intracellular water and phase angle increased significantly (P<0.05) in men (7.8, 8.3, and 4.3%, respectively) and women (7.6, 11.7, and 5.8% respectively), with no significant difference between sexes (P>0.05). Bioimpedance resistance decreased (P<0.05) similarly in both sex (men=-4.8%, women=-3.8%). The results suggest that regardless of sex, progressive RT induces an increase in phase angle and a rise in cellular hydration.

Composición corporal y concentraciones de adipocitoquinas en hemodiálisis: la ganancia de grasa abdominal como factor de riesgo cardiovascular añadido

IntroductionAbdominal fat and its increment over time in particular has become a cardiovascular risk factor in uraemic patients. ObjectivesTo analyse changes in abdominal fat in haemodialysis patients over one year and study their possible correlation with the variation in adipocytokine serum levels. As a secondary objective, we tried to validate the data obtained by bioelectrical impedance analysis (BIA) with data obtained by dual X-ray absorptiometry (DXA). Material and methodsA prospective one-year study was performed in 18 patients on haemodialysis (HD). In each patient, body composition by BIA and DXA was estimated at baseline and after one year. Several adipocytokine and biochemical parameters were determined. ResultsA significant increase in phase angle [4.8° (4.1-5.6) vs. 5.2° (4.4-5.8), P<.05], BIA intracellular water [48.3% (43.1-52.3) vs. 50.3% (45.7-53.4), P<.05] and the ratio between the percentage of android/gynecoid (A/G) distribution of fat measured by DXA [1.00 (0.80-1.26) vs. 1.02 (0.91-1.30), P<.05] was observed. A statistically significant relationship between leptin and adiponectin concentrations and the percentage of fat mass measured by BIA, as well as the abdominal fat percentage estimated by DXA, was found (P<.01). ConclusionHD patients exhibit a gain in fat mass over time, especially in the abdomen, evidenced by an increased A/G ratio. These findings might explain the increased cardiovascular risk in these patients.

Effect of Mean Stress on 2A12-T4 Aluminum Alloy under Tension-Torsion Constant Amplitude Loading

Fatigue tests have been carried out to investigate the effects of mean-stress and phase-difference on the tension-torsion fatigue failure of 2A12-T4 aluminum alloy. The results show that for fully reversed tension-torsion loading, the fatigue life increases with the increase of phase angle, but the fatigue life decreases with the increase of phase angle, when mean-stress exists, both for shear mean-stress and normal mean-stress. Fracture appearance shows that the crack initiation is on the direction of maximum shear stress amplitude plane. Critical plane criteria based on the linear combination of the maximum shear stress amplitude and maximum normal stress are studied and further discussion on the drawbacks of this kind of criteria are performed.