Atrial structure and function in middle‐aged,physically‐active males and females: A cardiac magnetic resonance study

Recent studies have reported on an association between endurance sport, atrial enlargement and the development of lone atrial fibrillation in younger, male cohorts. The atrial morphology and function of middle‐aged, physically‐active males and females have not been well studied. We hypothesized that middle‐aged males would demonstrate larger left atrium (LA) and right atrium (RA) volumes compared to females, but atrial function would not differ. LA and RA volume and function were evaluated at rest in healthy adults, using a standardized 3.0Tesla cardiac magnetic resonance protocol. Physical activity, medical history, and maximal oxygen consumption (V˙O2peak) were also assessed. Physically‐active, middle‐aged men (n = 60; 54 ± 5 years old) and women (n = 30; 54 ± 5 years old) completed this study. Males had a higher body mass index, systolic blood pressure, and V˙O2peak than females (p < .05 for all), despite similar reported physical activity levels. Absolute and BSA and height‐indexed LA and RA maximum volumes were higher in males relative to females, despite no differences in ejection fractions (p < .05 for all). In multivariable regression, male sex p < .001) and V˙O2peak (p = .004) were predictors of LA volume (model R ² = 0.252), whereas V˙O2peak (p < .001), male sex (p = .03), and RV EF (p < .05) were predictors of RA volume (model R ² = 0.377). While middle‐aged males exhibited larger atrial volumes relative to females, larger, prospective studies are needed to explore the magnitude of physiologic atrial remodeling and functional adaptations in relation to phenotypic factors.     

Study on Hot Deformation Behavior of an Antibacterial 50Cr15MoVCu Tool Steel

Hot deformation behaviors of an antibacterial 50Cr15MoVCu tool steel were studied. The flow stress curves presented three typical characteristics: (i) a single peak dynamic recrystallization curve, (ii) a monotone incremental work-hardening curve, and (iii) the equilibrium dynamic recovery curve. The flow stress increased with the increase of the deformation rate at each deformation temperature and decreased with the increase of the deformation temperature at the same deformation rate. The thermal activation energy and material constants were Q of 461.6574 kJ/mol, A of 3.42 × 10¹⁷, and α of 0.00681 MPa⁻¹, respectively. The high temperature constitutive equation was: Z=ε˙expQ/RT=3.42×1017sinh0.0068×σ5.6807. Based on the processing maps and microstructure evolution, the best hot working process was a deformation temperature of 1050 °C and deformation rate of 0.001 s⁻¹.     

The origin of circulating CD36 in type 2 diabetes

Objective:

Elevated plasma levels of the fatty acid transporter, CD36, have been shown to constitute a novel biomarker for type 2 diabetes mellitus (T2DM). We recently reported such circulating CD36 to be entirely associated with cellular microparticles (MPs) and aim here to determine the absolute levels and cellular origin(s) of these CD36+MPs in persons with T2DM.

Design:

An ex vivo case-control study was conducted using plasma samples from 33 obese individuals with T2DM (body mass index (BMI)=39.9±6.4 kg m⁻²; age=57±9 years; 18 male:15 female) and age- and gender-matched lean and obese non-T2DM controls (BMI=23.6±1.8 kg m⁻² and 33.5±5.9 kg m⁻², respectively). Flow cytometry was used to analyse surface expression of CD36 together with tissue-specific markers: CD41, CD235a, CD14, CD105 and phosphatidyl serine on plasma MPs. An enzyme-linked immunosorbent assay was used to quantify absolute CD36 protein concentrations.

Results:

CD36+MP levels were significantly higher in obese people with T2DM (P<0.00001) and were primarily derived from erythrocytes (CD235a+=35.8±14.6%); although this did not correlate with haemoglobin A_1c. By contrast, the main source of CD36+MPs in non-T2DM individuals was endothelial cells (CD105+=40.9±8.3% and 33.9±8.3% for lean and obese controls, respectively). Across the entire cohort, plasma CD36 protein concentration varied from undetectable to 22.9 μg ml⁻¹ and was positively correlated with CD36+MPs measured by flow cytometry (P=0.0006) but only weakly associated with the distribution of controls and T2DM (P=0.021). Multivariate analysis confirmed that plasma CD36+MP levels were a much better biomarker for diabetes than CD36 protein concentration (P=0.009 vs P=0.398, respectively).

Conclusions:

Both the levels and cellular profile of CD36+MPs differ in T2DM compared with controls, suggesting that these specific vesicles could represent distinct biological vectors contributing to the pathology of the disease.     

Recovery of respiratory gas exchange after exercise in adults with congenital heart disease

Background

Delayed gas exchange kinetics in the early recovery period after exercise testing has been reported in children and adults with congenital heart disease (ACHD). Our objective was to compare early and late phase recovery kinetics in three groups of ACHD-patients.

Methods

Sixty-seven adults with complex ACHD (33 repaired tetralogy of Fallot, 19 Fontan operations, and 15 transposition complexes) and 10 healthy controls underwent symptom-limited cardiopulmonary exercise testing measuring gas-exchange kinetics over a 10 minute recovery period. Changes within the first minute of recovery and late changes, characterized as the time to reach 50% of peak values (T_1/2), were compared between groups.

Results

Recovery of VO₂ in early and late recoveries was significantly delayed in all ACHD-patients compared to controls without significant differences between patient groups. VO₂-recovery at 1 min compared between patients and controls was − 7.2 ± 4.0 versus − 17.0 ± 4.5 ml·kg·min^− 1 and T_1/2 VO₂ was 147 ± 62 versus 66 ± 23 s (p < 0.0001 for both comparisons). Similar changes were observed for VCO₂-recovery. Peak VO₂ (ml·kg·min^− 1) demonstrated strong correlation with VO₂-recovery at 1 min (ml·kg·min^− 1, r = 0.90) and moderate correlation with T_1/2 VO₂ (r = − 0.70).

Conclusion

Gas exchange recovery after exercise testing is prolonged in ACHD-patients, independent of the congenital heart lesion but related to peak aerobic capacity, particularly recovery kinetics within the first minute. Recovery kinetics at 1 min is a useful and easily obtained clinical measure that warrants further study as a prognostic measure.     

Moderate-intensity exercise with blood flow restriction on cardiopulmonary kinetics and efficiency during a subsequent high-intensity exercise in young women: A cross-sectional study

Blood flow restriction (BFR) training applied prior to a subsequent exercise has been used as a method to induce changes in oxygen uptake pulmonary kinetics (V˙O_2P) and exercise performance. However, the effects of a moderate-intensity training associated with BFR on a subsequent high-intensity exercise on V˙O_2P and cardiac output (Q_T) kinetics, exercise tolerance, and efficiency remain unknown.This prospective physiologic study was performed at the Exercise Physiology Lab, University of Brasilia. Ten healthy females (mean ± SD values: age = 21.3 ± 2.2 years; height = 1.6 ± 0.07 m, and weight = 55.6 ± 8.8 kg) underwent moderate-intensity training associated with or without BFR for 6 minutes prior to a maximal high-intensity exercise bout. V˙O_2P, heart rate, and Q_T kinetics and gross efficiency were obtained during the high-intensity constant workload exercise test.No differences were observed in V˙O_2P, heart rate, and Q_T kinetics in the subsequent high-intensity exercise following BFR training. However, exercise tolerance and gross efficiency were significantly greater after BFR (220 ± 45 vs 136 ± 30 seconds; P < .05, and 32.8 ± 6.3 vs 27.1 ± 5.4%; P < .05, respectively), which also resulted in lower oxygen cost (1382 ± 227 vs 1695 ± 305 mL min^–1).We concluded that moderate-intensity BFR training implemented prior to a high-intensity protocol did not accelerate subsequent V˙O_2P and Q_T kinetics, but it has the potential to improve both exercise tolerance and work efficiency at high workloads.     

Measures of body fat in South Asian adults

Background:

South Asian people who originate from the Indian subcontinent have greater percent body fat (%BF) for the same body mass index (BMI) compared with white Caucasians. This has been implicated in their increased risk of type 2 diabetes and cardiovascular disease. There is limited information comparing different measures of body fat in this ethnic group.

Objectives:

The objectives of this study were: (1) to investigate the correlation of %BF measured by a foot-to-foot bioelectrical impedance analysis (FF-BIA) against the BOD POD, a method of air-displacement plethysmography, and (2) to determine the correlations of simple anthropometric measures, (that is, BMI, body adiposity index (BAI), waist circumference (WC), hip circumference (HC) and waist-to-hip ratio (WHR)) against the BOD POD measure of body fat.

Methods:

Eighty apparently healthy South Asian men and women were recruited from the community, and measurements of height, weight, WC, HC and body composition using Tanita FF-BIA and BOD POD were taken.

Results:

The mean±s.d. age of participants was 27.78±10.49 years, 42.5% were women, and the mean BMI was 22.68±3.51 kg m⁻². The mean body fat (%BF) calculated by FF-BIA and BOD POD was 21.94±7.88% and 26.20±8.47%, respectively. The %BF calculated by FF-BIA was highly correlated with the BOD POD (Pearson''s r=0.83, P<0.001), however, FF-BIA underestimated %BF by 4.3%. When anthropometric measures were compared with % BF by BOD POD, the BAI showed the strongest correlation (r=0.74) and the WHR showed the weakest (r=0.33). BAI generally underestimated %BF by 2.6% in comparison with %BF by BOD POD. The correlations of BOD POD with other measures of %BF were much stronger in subjects with a BMI >21 kg m⁻² than those with a BMI ⩽21 kg m⁻².

Conclusion:

The FF-BIA and BAI estimates of %BF are highly correlated with that of BOD POD among people of South Asian origin, although both methods somewhat underestimate % BF. Furthermore, their correlations with % BF from BOD POD are significantly weakened among men and women with a BMI ⩽21 kg m⁻².     

Specific appetite,energetic and metabolomics responses to fat overfeeding in resistant-to-bodyweight-gain constitutional thinness

Background:

Contrasting with obesity, constitutional thinness (CT) is a rare condition of natural low bodyweight. CT exhibits preserved menstruation in females, no biological marker of undernutrition, no eating disorders but a bodyweight gain desire. Anorexigenic hormonal profile with high peptide tyrosine tyrosine (PYY) was shown in circadian profile. CT could be considered as the opposite of obesity, where some patients appear to resist diet-induced bodyweight loss.

Objective:

The objective of this study was to evaluate appetite regulatory hormones in CTs in an inverse paradigm of diet-induced weight loss.

Methods:

A 4-week fat overfeeding (2640 kJ excess) was performed to compare eight CT women (body mass index (BMI)<17.5 kg m⁻²) to eight female controls (BMI 18.5–25 kg m⁻²). Appetite regulatory hormones profile after test meal, food intake, bodyweight, body composition, energy expenditure and urine metabolomics profiles were monitored before and after overfeeding.

Results:

After overfeeding, fasting total and acylated ghrelin were significantly lower in CTs than in controls (P=0.01 and 0.03, respectively). After overfeeding, peptide tyrosine tyrosine (PYY) and glucagon-like-peptide 1 both presented earlier (T15 min vs T30 min) and higher post-meal responses (incremental area under the curve) in CTs compared with controls. CTs failed to increase bodyweight (+0.22±0.18 kg, P=0.26 vs baseline), contrasting with controls (+0.72±0.26 kg, P=0.03 vs baseline, P=0.01 vs CTs). Resting energy expenditure increased in CTs only (P=0.031 vs baseline). After overfeeding, a significant negative difference between total energy expenditure and food intake was noticed in CTs only (−2754±720 kJ, P=0.01).

Conclusion:

CTs showed specific adaptation to fat overfeeding: overall increase in anorexigenic hormonal profile, enhanced post prandial GLP-1 and PYY and inverse to controls changes in urine metabolomics. Overfeeding revealed a paradoxical positive energy balance contemporary to a lack of bodyweight gain, suggesting yet unknown specific energy expenditure pathways in CTs.     

Printed Flexible Thermoelectric Nanocomposites Based on Carbon Nanotubes and Polyaniline

A new era of composite organic materials, nanomaterials, and printed electronics is emerging to the applications of thermoelectric generators (TEGs). Special attention is focused on carbon nanomaterials and conducting polymers, and the possibility to form pastes and inks for various low-cost deposition techniques. In this work, we present a novel approach to the processing of composite materials for screen-printing based on carbon nanotubes (CNTs) and polyaniline (PANI), supported with a dielectric polymer vehicle. Three different types of such tailor-made materials were prepared, with a functional phase consisted of carbon nanotubes and polyaniline composites fabricated with two methods: dry mixing of PANI CNT powders and in situ polymerisation of PANI with CNT. These materials were printed on flexible polymer substrates, exhibiting outstanding mechanical properties. The best parameters obtained for elaborated materials were σ=405.45 S·m−1, S=15.4 μV·K−1, and PF=85.2 nW·m−1K−2, respectively.     

Quinary structure modulates protein stability in cells

Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein–matrix contacts that comprise quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions. We use NMR-detected H/D exchange to quantify quinary interactions between the B1 domain of protein G and the cytosol of Escherichia coli. We demonstrate that a surface mutation in this protein is 10-fold more destabilizing in cells than in buffer, a surprising result that firmly establishes the significance of quinary interactions. Remarkably, the energy involved in these interactions can be as large as the energies that stabilize specific protein complexes. These results will drive the critical task of implementing quinary structure into models for understanding the proteome.The inside of cells is packed with macromolecules whose concentrations reach 300–400 g/L (1). Compared with the ideal (dilute) environments conventionally used to study proteins, crowding inside cells can significantly alter the biophysical landscape of proteins, including their equilibrium thermodynamic stability (2–6). Experimental and computational efforts establish that crowding effects arise from a combination of short-range (steric) repulsions and longer-range (often called soft) interactions between macromolecules (7–13). Despite a growing number of in-cell protein studies (2–6), there is no quantitative information about the energetics of quinary interactions.Amide proton exchange experiments have been used for more than 50 y to measure equilibrium protein stability, defined as the Gibbs free energy required to open the protein and expose individual backbone amide protons to solvent, ΔGop°′ (14). For the B1 domain of protein G (GB1), ΔGop°′ equals −RTln(k_obs/k_uns), where R is the gas constant, T is the absolute temperature, k_obs is the observed rate of exchange, and k_uns is the rate in an unstructured peptide (6). We know that the cytoplasm does not affect k_uns (15). Most importantly, we know that for exchange under these conditions ΔGop°′ approximates the free energy required to denature the protein, ΔGden°′ (6). Therefore, these experiments provide a thermodynamically rigorous measure of equilibrium global protein stability. Using this information, we quantified the stability of GB1 at the residue level in Escherichia coli (6) via NMR-detected backbone amide hydrogen/deuterium exchange (16).Thermodynamic cycles (17) can be used to quantify the energetics of interactions between proteins in specific protein complexes (17, 18) and between side chains in globular proteins (19, 20). Briefly, the individual effects of two single-site amino acid changes are compared with the combined effect of both mutations. If the sites interact, the sum of the contributions from the single-site changes will not equal the contribution from the double mutant. The difference between the two values measures the strength of the interaction.We realized that transferring a variant (“var”) from buffer (“buff”) to cells (“cell”) is analogous to making a second mutation to the protein (Fig. 1 and SI Appendix, Fig. S1). Discrepancies in the horizontal (and vertical) sides of Fig. 1 define the free energy (δΔΔGint°′) associated with quinary interactions. Differences in the residue-level stability change caused by the mutation (ΔΔGop,mut°′) in cells and in buffer are used to calculate δΔΔGop,int°′:δΔΔGint°′=(ΔGcell,var°′−ΔGcell,WT°′)−(ΔGbuff,var°′−ΔGbuff,WT°′)=ΔΔGmut,cell°′−ΔΔGmut,buff°′=ΔΔGcell,var°′−ΔΔGcell,WT°′.A negative value of δΔΔGint°′ indicates the introduction of an attractive interaction (relative to WT) upon transferring the mutant from buffer to cells.Open in a separate windowFig. 1.Thermodynamic cycle used to quantify quinary interactions.     

Randomized trial of nutrition education added to internet-based information and exercise at the work place for weight loss in a racially diverse population of overweight women

Objective:

Obesity in the United States is highly prevalent, approaching 60% for black women. We investigated whether nutrition education sessions at the work place added to internet-based wellness information and exercise resources would facilitate weight and fat mass loss in a racially diverse population of overweight female employees.

Methods:

A total of 199 (average body mass index 33.9±6.3 kg m⁻²) nondiabetic women (57% black) at our institution were randomized to a 6-month program of either internet-based wellness information (WI) combined with dietitian-led nutrition education group sessions (GS) weekly for 3 months and then monthly with shift in emphasis to weight loss maintenance (n=99) or to WI alone (n=100). All were given access to exercise rooms convenient to their work site. Fat mass was measured by dual-energy X-ray absorptiometry.

Results:

WI+GS subjects lost more weight than WI subjects at 3 months (−2.2±2.8 vs −1.0±3.0 kg, P>0.001). Weight (−2.7±3.9 vs −2.0±3.9 kg) and fat mass (−2.2±3.1 vs −1.7±3.7 kg) loss at 6 months was significant for WI+GS and WI groups (both P<0.001), but without significant difference between groups (both P>0.10); 27% of the WI+GS group achieved ⩾5% loss of initial weight as did 18% of the WI group (P=0.180). Blacks and whites similarly completed the study (67 vs 74%, P=0.303), lost weight (−1.8±3.4 vs −3.3±5.2 kg, P=0.255) and fat mass (−1.6±2.7 vs −2.5±4.3 kg, P=0.532), and achieved ⩾5% loss of initial weight (21 vs 32%, P=0.189), irrespective of group assignment.

Conclusion:

Overweight women provided with internet-based wellness information and exercise resources at the work site lost weight and fat mass, with similar achievement by black and white women. Additional weight loss benefit of nutrition education sessions, apparent at 3 months, was lost by 6 months and may require special emphasis on subjects who fail to achieve weight loss goals to show continued value.     

Exercise-training-induced changes in metabolic capacity with age: the role of central cardiovascular plasticity

Although aging is typically associated with a decline in maximal oxygen consumption (VO_2max), young and old subjects, of similar initial muscle metabolic capacity, increased quadriceps VO_2max equally when this small muscle mass was trained in isolation. As it is unclear if this preserved exercise-induced plasticity with age is still evident with centrally challenging whole body exercise, we assessed maximal exercise responses in 13 young (24 ± 2 years) and 13 old (60 ± 3 years) males, matched for cycling VO_2max (3.82 ± 0.66 and 3.69 ± 0.30 L min⁻¹, respectively), both before and after 8 weeks of high aerobic intensity cycle exercise training. As a consequence of the training both young and old significantly improved VO_2max (13 ± 6 vs. 6 ± 7 %) and maximal power output (20 ± 6 vs. 10 ± 6 %, respectively) from baseline, however, the young exhibited a significantly larger increase than the old. Similarly, independently assessed maximal cardiac output (Q_max) tended to increase more in the young (16 ± 14 %) than in the old (11 ± 12 %), with no change in a-vO₂ difference in either group. Further examination of the components of Q_max provided additional evidence of reduced exercise-induced plasticity in both maximal heart rate (young −3 %, old 0 %) and stroke volume (young 19 ± 15, old 11 ± 11 %) in the old. In combination, these findings imply that limited central cardiovascular plasticity may be responsible, at least in part, for the attenuated response to whole body exercise training with increasing age.     

Broad-spectrum β-lactams in obese non-critically ill patients

Objectives:

Obesity may alter the pharmacokinetics of β-lactams. The goal of this study was to evaluate if and why serum concentrations are inadequate when standard β-lactam regimens are administered to obese, non-critically ill patients.

Subjects and methods:

During first year, we consecutively included infected, obese patients (body mass index (BMI) ⩾30 kg m⁻²) who received meropenem (MEM), piperacillin-tazobactam (TZP) or cefepime/ceftazidime (CEF). Patients with severe sepsis or septic shock, or those hospitalized in the intensive care unit were excluded. Serum drug concentrations were measured twice during the elimination phase by high-performance liquid chromatography. We evaluated whether free or total drug concentrations were >1 time (fT>minimal inhibition concentration (MIC)) or >4 times (T>4MIC) the clinical breakpoints for Pseudomonas aeruginosa during optimal periods of time: ⩾40% for MEM, ⩾50% for TZP and ⩾70% for CEF.

Results:

We included 56 patients (median BMI: 36 kg m⁻²): 14 received MEM, 31 TZP and 11 CEF. The percentage of patients who attained target fT>MIC and T>4MIC were 93% and 21% for MEM, 68% and 19% for TZP, and 73% and 18% for CEF, respectively. High creatinine clearance (107 (range: 6–398) ml min⁻¹) was the only risk factor in univariate and multivariate analyses to predict insufficient serum concentrations.

Conclusions:

In obese, non-critically ill patients, standard drug regimens of TZP and CEF resulted in insufficient drug concentrations to treat infections due to less susceptible bacteria. Augmented renal clearance was responsible for these low serum concentrations. New dosage regimens need to be explored in this patient population (EUDRA-CT: 2011-004239-29).     

Influence of Si,Cu, B,and Trace Alloying Elements on the Conductivity of the Al-Si-Cu Alloy

The influence of Si, Cu, B, and trace alloying elements on the conductivity of aluminum die cast 12 (ADC12) alloy was investigated. The conductivity decreased linearly with increasing volume fraction of the Si phase attributed to a linear decrease of the volume of the more conductive Al phase through a rule of mixtures. The conductivity also decreased with increasing Cu content, between 0~3%. The conductivity increased with increasing B content, reached the peak at 0.02% B and thereafter decreased somewhat. The mechanism was that B reacted with the transition element in the Al phase to form boride, decreasing the transition element concentration in the Al lattice, and decreasing the lattice constant. The thermal conductivity, λ, was related to the electrical conductivity, σ, by means of λ=LTσ+λg, where L is the apparent Lorentz constant, 1.86 × 10⁻⁸; T is the absolute temperature, 293 K; λ_g is the lattice conductivity, 42.3 W/(m·K).     

The missing enzymatic link in syntrophic methane formation from fatty acids

The microbial production of methane from organic matter is an essential process in the global carbon cycle and an important source of renewable energy. It involves the syntrophic interaction between methanogenic archaea and bacteria that convert primary fermentation products such as fatty acids to the methanogenic substrates acetate, H₂, CO₂, or formate. While the concept of syntrophic methane formation was developed half a century ago, the highly endergonic reduction of CO₂ to methane by electrons derived from β-oxidation of saturated fatty acids has remained hypothetical. Here, we studied a previously noncharacterized membrane-bound oxidoreductase (EMO) from Syntrophus aciditrophicus containing two heme b cofactors and 8-methylmenaquinone as key redox components of the redox loop–driven reduction of CO₂ by acyl–coenzyme A (CoA). Using solubilized EMO and proteoliposomes, we reconstituted the entire electron transfer chain from acyl-CoA to CO₂ and identified the transfer from a high- to a low-potential heme b with perfectly adjusted midpoint potentials as key steps in syntrophic fatty acid oxidation. The results close our gap of knowledge in the conversion of biomass into methane and identify EMOs as key players of β-oxidation in (methyl)menaquinone-containing organisms.

The microbial conversion of natural polymers into methane plays an important role in the global carbon cycle and accounts for more than one-half of all methane produced on Earth per year (1, 2). Methane is formed in anoxic environments, including marine and freshwater sediments, but also in biogas reactors of wastewater treatment plants and other engineered systems. A complex syntrophic association between fermenting bacteria and methanogenic archaea is involved in the degradation of biomass to CH₄ and CO₂. Primary fermenting bacteria hydrolyze complex polymers into monomers and degrade them mainly into short chain fatty acids (scFA) and alcohols. Secondary fermenting bacteria then oxidize these products to the methanogenic substrates acetate, H₂, CO₂, and formate that are finally converted into methane by hydrogenotrophic or acetotrophic archaea (Fig. 1A) (3). The reduction of CO₂ to CH₄ depends on interspecies electron transfer from secondary fermenting bacteria to methanogenic archaea usually via the diffusible low-potential carriers formate and/or H₂ (3–5) or, as recently proposed, directly via nanowires (6).Open in a separate windowFig. 1.Syntrophic degradation of organic matter to methane. (A) Major metabolic processes involving primary fermenters, secondary fermenters, and methanogenic archaea (for simpler presentation, acetogenic conversion of monomers is not depicted here). (B) Model for syntrophic β-oxidation of butyrate to two acetates coupled to the reduction of protons or CO₂. The enzyme mediating electron transfer from reduced ETF to FDH has not been studied before and was assigned to noncharacterized DUF224 based on omics-based predictions.The oxidation of scFA to acetate coupled to the reduction of H⁺ or CO₂ is endergonic under standard conditions (+48 kJ/mol butyrate) but becomes clearly exergonic at an H₂ partial pressure below 10 Pa (3, 7). On the other side, the H₂ threshold partial pressure of hydrogenotrophic methanogenesis is around 8 Pa corresponding to E′(2H⁺/H₂) ∼ −290 mV or around 10 µM formate, resulting in similar values for the CO₂/formate redox couple (2). The syntrophic oxidation of the scFA model compound butyrate to acetate is accomplished by gram-positive Firmicutes (model organism Syntrophomonas wolfei) or gram-negative Deltaproteobacteria (model organism Syntrophus aciditrophicus) (3, 4, 7). It proceeds via two unequal β-oxidation steps (SI Appendix, Fig. 1) (8, 9): 1) Butyryl-CoA is oxidized to crotonyl-CoA by an acyl-CoA dehydrogenase (DH) (E°′ ∼ −10 mV) (10) with an electron-transferring flavoprotein (ETF) serving as electron acceptor, and 2) the 3-hydroxybutyryl-CoA formed by crotonase is subsequently oxidized to acetoacetyl-CoA by 3-hydroxybutyryl-CoA DH (ΔE°′ = −250 mV) (11) using NAD⁺ as acceptor. The reduction of H⁺ or CO₂ by the NADH formed is feasible under syntrophic conditions, whereas butyryl-CoA oxidation coupled to H⁺ or CO₂ reduction has to overcome a gap of ΔE ∼ −280 mV, giving ΔG°′ ∼ +54 kJ ⋅ mol^–1 (3–5). Considering that only one ATP is gained via substrate-level phosphorylation, the energy metabolism of syntrophic butyrate oxidation has remained enigmatic.Omics-based studies have led to the proposal of models for energy coupling processes during syntrophic scFA oxidation (12–16). The redox loop model is based on the identification of a putative membrane-bound gene product (DUF224) (14–16). It proposes that electrons are transferred from acyl-CoA via ETF, DUF224, and menaquinone (MK) to a membrane-bound formate dehydrogenase (FDH) or hydrogenase driven by the translocation of protons to the cytoplasm, resulting in two energetically unequal half reactions:Acyl-CoA + MK →Enoyl-CoA + MKH2 ΔG°’ = +12.5 kJ mol–1CO2+ MKH2→Formate + H++ MKΔG’ = +41.5 kJ mol–1.In agreement, a protonophore inhibited formation of H₂ from butyrate in whole-cell suspension of S. wolfei (17), and MK was reported in S. wolfei and S. aciditrophicus (12, 17). In an alternative model, an electron-confurcating ETF couples endergonic reduction of NAD⁺ by ETF_red to the exergonic reduction of NAD⁺ by reduced ferredoxin (Fd_red^–) (18). The NADH formed then may serve as an electron donor for a cytoplasmic FDH. Biochemical evidence for either of the two models is lacking.Here, we study the missing membrane components that link fatty acid oxidation to CO₂ reduction during syntrophic methane production. We provide biochemical evidence that a membrane-bound diheme oxidoreductase and a modified methylmenaquinone with perfectly adjusted redox potentials are the key players of this process. We further propose that related enzymes play a previously overlooked role in the lipid catabolism of the majority of microorganisms.     

Effects of endurance,circuit, and relaxing training on cardiovascular risk factors in hypertensive elderly patients

Recommendations for prevention of cardiovascular diseases (CVDs) risk factors among older adults highlighted the importance of exercise-based interventions, including endurance training (ET). However, the evidence of efficacy of other interventions based on short-bouts of exercise (circuit training, CT), and the practice of breath-control and meditation (relaxing training, RT) is growing. The aim of this study was to elucidate if CT or RT are equally effective in CVD risk factors reduction compared to ET. To this purpose, in 40 elderly participants, with clinically diagnosed grade 1 hypertension, resting blood pressure, blood glucose, and cholesterol levels, peak oxygen uptake (V˙o2peak), mechanical efficiency and quality of life were evaluated before and after 12 weeks of ET, CT, and RT treatments. Resting blood pressure reduced significantly in all groups by ∼11 %. In ET, blood cholesterol levels (−18 %), V˙o2peak (+8 %), mechanical efficiency (+9 %), and quality of life scores (+36 %) ameliorated. In CT blood glucose levels (−11 %), V˙o2peak (+7 %) and quality of life scores (+35 %) were bettered. Conversely, in RT, the lower blood pressure went along only with an improvement in the mental component of quality of life (+42 %). ET and CT were both appropriate interventions to reduce CVDs risk factors, because blood pressure reduction was accompanied by decreases in blood glucose and cholesterol levels, increases in V˙o2peak, mechanical efficiency, and quality of life. Although RT influenced only blood pressure and quality of life, this approach would be an attractive alternative for old individuals unable or reluctant to carry out ET or CT.     

Sustainable and feasible reagent-free electro-Fenton via sequential dual-cathode electrocatalysis

Electro-Fenton processes aim at producing oxidizing radicals with fewer added chemicals and residues but are still unable to completely eliminate both. This study demonstrates that a reagent-free electro-Fenton process that runs solely on oxygen and electricity can be achieved by sequential dual-cathode electrocatalysis. H₂O₂ is produced on an electrodeposited PEDOT on carbon cloth (PEDOT/CC) cathode and subsequently converted to hydroxyl radicals on a stainless-steel–mesh cathode. The dual-cathode system demonstrates efficient decolorization and total organic carbon (TOC) removal toward organic dyes at optimized cathodic potentials of −0.9 V for PEDOT/CC and −0.8 V for the stainless-steel mesh. The sequential dual-cathode process also displays high reusability, no iron leaching, high removal efficiency using air instead of oxygen, and low installation and operation costs. This work demonstrates a preeminent and commercially viable example of pollution control rendered by the “catalysis instead of chemical reagent” philosophy of green chemistry.

Discovered in the 1900s (1), the Fenton reaction produces hydroxyl radicals (·OH) from hydrogen peroxide (H₂O₂) and ferrous ions (Fe²⁺) (2). The highly oxidizing ·OH can degrade organic compounds (3), while the radical’s short life eliminates its secondary pollution. These two combined merits lead to fast development of advanced oxidation processes, which rely on radical chemistry to degrade/mineralize organic pollutants in water and wastewater. Despite its ability to remove virtually all organic pollutants, the original Fenton process involves the use of H₂O₂ and Fe²⁺, making the process costly in large-scale applications. Moreover, the use of Fe²⁺ introduces secondary pollution (i.e., ferrous residue in the form of color in the effluent or ferric sludge, both requiring further treatment). To tackle these shortcomings, electro-Fenton has been rigorously studied, aiming at in situ generation of H₂O₂, cathodic regeneration of Fe²⁺, or a combination of both.Electrochemical H₂O₂ production has been achieved on numerous carbon materials (4–7) and certain transition metal compounds (8, 9) because of their two-electron oxygen reduction reaction (ORR) pathway (Eq. 1). Despite the elimination of H₂O₂ addition, majority of the current electro-Fenton processes still involve the use of Fe²⁺, either externally added or generated on a sacrificial iron-containing anode (10). Fenton or electro-Fenton processes generally become less efficient at pH > 3 because of the formation of Fe(OH)⁺ complex ions, which are no longer active toward H₂O₂ conversion to ·OH. Other transition metals can also catalyze this reaction, but the pH effect and leaching problem still exist (11). In fact, metal-catalyzed Fenton generally suffers from a pH dilemma (i.e., low ·OH generation rate at high pH and high metal leaching rate at low pH). A recent endeavor (12) achieves low leaching rate by single-atom copper anchored on C₃N₄. However, this process runs at neutral pH, which is intrinsically less efficient in terms of ·OH generation than a mild acidic condition. Moreover, the regeneration of monovalent copper (reduction of Cu²⁺ to Cu⁺) relies on oxidation of H₂O₂ to produce oxygen, leading to reduced H₂O₂ utilization toward ·OH.In fact, H₂O₂ can also be activated by electrocatalysis on nonsacrificial cathodes (Eq. 2) to form ·OH (13, 14). Therefore, it is theoretically feasible to sequentially convert O₂ to H₂O₂ and then ·OH by two cathodic reactions. Such a process is highly desirable since it is completely free from added chemical reagents while yielding no ferrous or other metal residue in the treated water. This strategy has been demonstrated in recent studies which use N-doped graphene cathodes, of which the graphitic and pyridinic nitrogen are responsible for the generation and activation of H₂O₂, respectively (15–17). However, this method may not be feasible in practical applications because of the high cost of graphene and moreover the difficulty in controlling its nitrogen doping level and type. Similarly, reduction of O₂ to ·OH has also been achieved in a stepwise manner at different active sites on FeCo alloy encapsulated in carbon (18) with carboxylic functionality. Again, preparation of such electrocatalysts involves complicated nanosynthetic methods, posing a barrier to its large-scale implementation. Aside from these rare attempts, sequential cathodic electro-Fenton process of O₂ → H₂O₂ → ·OH has not been reported elsewhere, probably because the two cathodic reactions require different cathodes and cathodic potentials. Attempting to achieve both reactions on the same cathode can probably lead to preferential reduction of H₂O₂ to water rather than ·OH (19).O2 + 2H+ + 2e− → H2O2.[1]H2O2 + e− → ·OH + OH−.[2]Herein, we report a reagent-free electro-Fenton system in which the H₂O₂ generation and conversion to ·OH are achieved by a two-step sequential electrocatalysis at poly(3,4-ethylenedioxythiophene) (PEDOT)-modified carbon cloth and stainless-steel–mesh cathodes. This process is completely free from added chemical reagents and hence introduces no secondary pollution. Aside from being sustainable, this process also demonstrates high commercial feasibility owing to the use of low-cost, durable, and scalable electrode materials and moderate energy consumption.     

Effect of PGX,a novel functional fibre supplement,on subjective ratings of appetite in overweight and obese women consuming a 3-day structured,low-calorie diet

Introduction:

Dietary factors that help control perceived hunger might improve adherence to calorie-reduced diets.

Objectives:

The objective of the study was to investigate the effect of supplementing a three-day, low-calorie diet with PolyGlycopleX (PGX), a highly viscous fibre, on subjective ratings of appetite compared with a placebo.

Methods:

In a double-blind crossover design with a 3-week washout, 45 women (aged 38±9 years, body mass index 29.9±2.8 kg m⁻²) were randomised to consume a 1000-kcal per day diet for 3 days, supplemented with 5 g of PGX or placebo at each of breakfast, lunch and dinner. Subjective appetite was assessed using 100 mm visual analogue scales that were completed daily before, between and after consumption of meals.

Results:

Thirty-five women completed the study. Consumption of PGX compared with placebo led to significantly lower mean area under the curve for hunger on day 3 (440.4 versus 375.4; P=0.048), prospective consumption on day 3 (471.0 versus 401.8; P=0.017) and the overall 3-day average (468.6 versus 420.2; P=0.026). More specifically, on day 3 PGX significantly reduced total appetite, hunger, desire to eat and prospective consumption for 2.5 and 4.5 h after lunch and before dinner times, with hunger also being reduced 2.5 h after dinner (P<0.05).

Conclusion:

The results show that adding 5 g of PGX to meals during consumption of a low-calorie diet reduces subjective ratings of prospective consumption and increases the feelings of satiety, especially during afternoon and evening. This highly viscous polysaccharide may be a useful adjunct to weight-loss interventions involving significant caloric reductions.     

Effectiveness of a Physical Activity and Weight Loss Intervention for Middle-Aged Women: Healthy Bodies,Healthy Hearts Randomized Trial

BACKGROUND

Physical inactivity is a significant risk factor for cardiovascular disease and remains highly prevalent in middle-aged women.

OBJECTIVE

We hypothesized that an interventionist-led (IL), primary-care–based physical activity (PA) and weight loss intervention would increase PA levels and decrease weight to a greater degree than a self-guided (SG) program.

DESIGN

We conducted a randomized trial.

PARTICIPANTS

Ninety-nine inactive women aged 45–65 years and with BMI ≥ 25 kg/m² were recruited from three primary care clinics.

INTERVENTIONS

The interventionist-led (IL) group (n = 49) had 12 weekly sessions of 30 min discussions with 30 min of moderate-intensity PA. The self-guided (SG) group (n = 50) received a manual for independent use.

MAIN MEASURES

Assessments were conducted at 0, 3, and 12 months; PA and weight were primary outcomes. Weight was measured with a standardized protocol. Leisure PA levels were assessed using the Modifiable Activity Questionnaire. Differences in changes by group were analyzed with a t-test or Wilcoxon rank-sum test. Mixed models were used to analyze differences in changes of outcomes by group, using an intention-to-treat principle.

KEY RESULTS

Data from 98 women were available for analysis. At baseline, mean (SD) age was 53.9 (5.4) years and 37 % were black. Mean weight was 92.3 (17.7) kg and mean BMI was 34.7 (5.9) kg/m². Median PA level was 2.8 metabolic equivalent hours per week (MET-hour/week) (IQR 0.0, 12.0). At 3 months, IL women had a significantly greater increase in PA levels (7.5 vs. 1.9 MET-hour/week; p = 0.02) than SG women; there was no significant difference in weight change. At 12 months, the difference between groups was no longer significant (4.7 vs. 0.7 MET-hour/week; p = 0.38). Mixed model analysis showed a significant (p = 0.048) difference in PA change between groups at 3 months only.

CONCLUSIONS

The IL intervention was successful in increasing the physical activity levels of obese, inactive middle-aged women in the short-term. No significant changes in weight were observed.

Electronic supplementary material

The online version of this article (doi:10.1007/s11606-014-3077-5) contains supplementary material, which is available to authorized users.KEY WORDS: physical activity, exercise, clinical trial, intervention     

The Relationship between Osteoinduction and Vascularization: Comparing the Ectopic Bone Formation of Five Different Calcium Phosphate Biomaterials

Objective: The objective of this study is to compare the bone induction of five kinds of calcium phosphate (Ca-P) biomaterials implanted in mice and explore the vascularization and particle-size-related osteoinductive mechanism. Methods: The following five kinds of Ca-P biomaterials including hydroxyapatite (HA) and/or tricalcium phosphate (TCP) were implanted in the muscle of 30 BALB/c mice (n = 6): 20 nm HA (20HA), 60 nm HA (60HA), 12 µm HA (12HA), 100 nm TCP (100TCP) and 12 µm HA + 100 nm TCP (HATCP). Then, all animals were put on a treadmill to run 30 min at a 6 m/h speed each day. Five and ten weeks later, three mice of each group were killed, and the samples were harvested to assess the osteoinductive effects by hematoxylin eosin (HE), Masson’s trichrome and safranine–fast green stainings, and the immunohistochemistry of the angiogenesis and osteogenesis markers CD31 and type I collagen (ColI). Results: The numbers of blood vessels were 139 ± 29, 118 ± 25, 78 ± 15, 65 ± 14 in groups HATCP, 100TCP, 60HA and 20HA, respectively, which were significantly higher than that of group 12HA (12 ± 5) in week 5 (p < 0.05). The area percentages of new bone tissue were (7.33 ± 1.26)% and (8.49 ± 1.38)% in groups 100TCP and HATCP, respectively, which were significantly higher than those in groups 20HA (3.27 ± 0.38)% and 60HA (3.43 ± 0.27)% (p < 0.05); however, no bone tissue was found in group 12HA 10 weeks after transplantation. The expression of CD31 was positive in new blood vessels, and the expression of ColI was positive in new bone tissue. Conclusions: Nanoscale Ca-P biomaterials could induce osteogenesis in mice muscle, and the osteoinductive effects of TCP were about 124% higher than those of 20HA and 114% higher than those of 60HA. The particle size of the biomaterials affected angiogenesis and osteogenesis. There was a positive correlation between the number of blood vessels and the area percentage of new bone tissue; therefore, osteoinduction is closely related to vascularization. Our results provide an experimental basis for the synthesis of calcium–phosphorus matrix composites and for further exploration of the osteoinductive mechanism.