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Age-related deterioration in turnover of collagen proteins accelerates extracellular matrix fibrosis and hinders adaptation to external stimuli. This project sought to understand factors that increase skeletal muscle fibrosis with age by studying what we term the dynamic protein pool. We hypothesized that the dynamic protein pool size of muscle collagen decreases with age, thus indicating a decrease in proteostatic maintenance (ie, ability to maintain proteostasis), and that failure to account for these changes impacts the interpretation of tracer-measured synthesis rates. We used deuterium oxide (D2O) labeling for up to 60 days in adult (6 months) and old (23 months) mice. The dynamic protein pool in adult skeletal muscle was 65% in tibialis anterior (TA), but only 28% in gastrocnemius (Gastroc). In aged muscle, the dynamic protein pool was further decreased to only 35% and 14% for TA and Gastroc, respectively. We showed that this loss in dynamic pool size was associated with increases in markers of fibrosis and decreased proteostatic maintenance. We demonstrate that aged muscle has higher rates of collagen protein synthesis and lower rates of collagen protein breakdown, which causes collagen accumulation. We further demonstrated that the normal assumption of complete protein renewal and the standard practice of taking a single sample with isotope labeling have profound impacts on interpretation of the genesis of fibrosis. Strategies to maintain muscle function with aging should focus on the dynamic protein pool with attention to methodological strategies to assess those changes. [ABSTRACT FROM AUTHOR]

Aim: Interventions that decrease atrophy during disuse are desperately needed to maintain muscle mass. We recently found that massage as a mechanotherapy can improve muscle regrowth following disuse atrophy. Therefore, we aimed to determine if massage has similar anabolic effects when applied during normal weight bearing conditions (WB) or during atrophy induced by hindlimb suspension (HS) in adult rats. Methods: Adult (10 months) male Fischer344‐Brown Norway rats underwent either hindlimb suspension (HS, n = 8) or normal WB (WB, n = 8) for 7 days. Massage was applied using cyclic compressive loading (CCL) in WB (WBM, n = 9) or HS rats (HSM, n = 9) and included four 30‐minute bouts of CCL applied to gastrocnemius muscle every other day. Results: Massage had no effect on any anabolic parameter measured under WB conditions (WBM). In contrast, massage during HS (HSM) stimulated protein turnover, but did not mitigate muscle atrophy. Atrophy from HS was caused by both lowered protein synthesis and higher degradation. HS and HSM had lowered total RNA compared with WB and this was the result of significantly higher ribosome degradation in HS that was attenuated in HSM, without differences in ribosomal biogenesis. Also, massage increased protein turnover in the non‐massaged contralateral limb during HS. Finally, we determined that total RNA degradation primarily dictates loss of muscle ribosomal content during disuse atrophy. Conclusion: We conclude that massage is an effective mechanotherapy to impact protein turnover during muscle disuse in both the massaged and non‐massaged contralateral muscle, but it does not attenuate the loss of muscle mass. [ABSTRACT FROM AUTHOR]

R3524 --> 881.4 --> Older individuals undergo more frequent inpatient hospitalizations and bedrest compared to younger persons, causing rapid losses of muscle mass and strength. Evidence suggests that only aged muscle fails to completely recover following disuse despite aged and adult muscle having similar levels of muscle loss. Current efforts to improve muscle recovery in older individuals are commonly aimed at increasing myofibrillar protein synthesis via mTOR stimulation despite recent evidence demonstrating that old muscle has chronically elevated levels of mTORC1 activity. We hypothesized that old muscle fails to fully recover muscle mass due to impaired proteostasis and not due limitations in protein synthesis. Methods: Adult (10 month) and old (30 month) F344BN rats were hindlimb unloaded (HU) for 14‐days to induce atrophy, followed by subsequent reloading (RE) to study muscle regrowth. During RE the rats were labeled with deuterium oxide (D2O) for 7, 15, 30, 45 or 60 days (n=4‐6 per timepoint per group) to determine bulk and individual protein synthesis and RNA synthesis. We also assessed muscle mass, fiber size by immunohistochemistry, mTORC1 signaling by western blot, and aggregate formation by tissue fractionation. Results: Adult and old gastrocnemius (GA) muscle had significant losses of muscle mass (359 mg ±55 and 724 mg ±60 loss respectively,p<0.05) and fiber size (1296 um2±202 and 1480 um2 ±142 loss respectively, p<0.01) with HU. While adult muscle fully recovered GA mass and fiber size by day 15, old GA muscle did not fully recover during the entire 60 days of RE (18% CSA and 11% mass loss still present). Despite limited mass and fiber size recovery in old muscle, GA myofibrillar protein synthesis rates (1.45 ±0.18 vs 2.28 ±0.24, FSR%, p<0.05) and mTORC1‐related signaling were higher in old muscle compared to adult. Additionally, GA RNA synthesis rates (2.79 ±0.139 vs 5.18 ±0.684, p<0.05) and RNA concentration (183 ng ±3.6 vs 249 ng ±13.9, p<0.05), which are markers of translational capacity, were also elevated in old muscle relative to adult during RE. Old muscle had higher levels of insoluble protein aggregates, a marker of impaired proteostasis, during RE compared to adult (1.2 ±0.09 vs 1.5 ±012 fold increase, p<0.05). Lastly, we assessed individual protein synthesis rates of the whole muscle proteome and discovered that old GA muscle had a larger number of proteins with increased synthesis rates compared to adult. In conclusion, these data strongly suggest that limitations in old muscle to recover after disuse are not due to limitations in protein synthesis but are instead due to impaired proteostasis with age. Therefore, understanding how proteostasis responds during these periods surrounding unloading in old muscle are critical to improve muscle recovery after disuse. [ABSTRACT FROM AUTHOR]

The article discusses research which was conducted to investigate the magnitude of dehydration and acute weight gain in mixed martial arts fighters before a competition. Researchers evaluated 40 fighters. They found that on average the fighters gained 4.4% of their body weight before a competition and that 39% appeared to have significant or serious dehydration.

The purpose of this study was to examine the effects of inter-repetition rest (IRR) on ratings of perceived exertion (RPE) in the power clean exercise in a multiple set protocol using peak power as an indication of fatigue. Ten resistance-trained males participated in four testing sessions which consisted of determination of a one repetition maximum (1RM) in the power clean exercise (session 1) and performance of three sets of six repetitions at 80% of 1RM with 0 (P0), 20 (P20), or 40 s (P40) IRR (sessions 2-4). Fatigue during all three conditions was indicated by a significant decrease in power of 9.0% (P0), 3.0% (P20) and 2.1% (P40), respectively. Significant difference in the rate of power decrease in P40 indicates less fatigue in comparison to P0 and P20. P40 resulted in a significantly lower RPE compared to P0 and P20 (7.43 ± 0.34, 6.46 ± 0.47, and 5.30 ± 0.55, respectively). RPE increased significantly ( p ≤ 0.01) within each set (5.26 ± 0.37, 6.46 ± 0.44, and 7.46 ± 0.53; sets 1, 2, and 3, respectively). Significant difference in average RPE between the conditions indicates that RPE is not a determinant of intensity (% of 1RM) but the rate of fatigue (decreases in peak power). In addition, the fact that RPE increased between sets 1, 2 and 3 during all conditions support the same conclusion. The results demonstrate that increasing IRR in power clean training decreases the perception of effort and is inversely related to the rate of fatigue. [ABSTRACT FROM AUTHOR]

Small noncoding microRNAs (miRNAs) are important regulators of skeletal muscle size, and circulating miRNAs within extracellular vesicles (EVs) may contribute to atrophy and its associated systemic effects. The purpose of this study was to understand how muscle atrophy and regrowth alter in vivo serum EV miRNA content. We also associated changes in serum EV miRNA with protein synthesis, protein degradation, and miRNA within muscle, kidney, and liver. We subjected adult (10 mo) F344/BN rats to three conditions: weight bearing (WB), hindlimb suspension (HS) for 7 days to induce muscle atrophy, and HS for 7 days followed by 7 days of reloading (HSR). Microarray analysis of EV miRNA content showed that the overall changes in serum EV miRNA were predicted to target major anabolic, catabolic, and mechanosensitive pathways. MiR-203a-3p was the only miRNA demonstrating substantial differences in HS EVs compared with WB. There was a limited association of EV miRNA content to the corresponding miRNA content within the muscle, kidney, or liver. Stepwise linear regression demonstrated that EV miR-203a-3p was correlated with muscle mass and muscle protein synthesis and degradation across all conditions. Finally, EV miR-203a-3p expression was significantly decreased in human subjects who underwent unilateral lower limb suspension (ULLS) to induce muscle atrophy. Altogether, we show that serum EV miR-203a-3p expression is related to skeletal muscle protein turnover and atrophy. We suggest that serum EV miR-203a-3p content may be a useful biomarker and future work should investigate whether serum EV miR-203a-3p content is mechanistically linked to protein synthesis and degradation. [ABSTRACT FROM AUTHOR]

This study examined the impact extreme volume-load differences for a single weekly exercise, when all other exercises' volume loads were similar, would have on American football performance variables after inseason resistance training (RT). Twenty male National Collegiate Athletic Association (NCAA) American footballers (18-23 years, 98.4 6 19.3 kg) were randomly assigned to an extreme high-volume low-intensity (EHVLI; n 5 11) group or a low-volume highintensity (LVHI; n 5 9) group. Subjects performed the same evidence-based RT exercises and volume loads for 8 weeks thrice weekly, with the only differences being once weekly unilateral reverse dumbbell lunge (EHVLI) or unilateral Hatfield safety bar back squat (LVHI) exercises performed with different volume loads. Performance variables were assessed 1 week before (PRE) and after (POST) 8 weeks of RT. A 2-way analysis of variance with repeated measures and the Sidak post hoc test were used (p, 0.05). Extreme high-volume low-intensity had no significant (p. 0.05) PRE-to-POST RT changes in muscular strength in 1 repetition maximum (251.8 6 48.7 to 274.6 6 61.3 kg) or power in vertical jump (79.2 6 8.8 to 78.2 6 10.8 cm). Conversely, LVHI had significant (p=0.05) PRE-to-POST RT improvements in strength (249.2654.4 to 284.1655.0 kg) and power (72.8611.4 to 76.3 6 10.0 cm). Furthermore, LVHI vs. EHVLI displayed significantly greater percentage difference increases from PRE values in muscular power (6.7% 6 7.2 vs. 21.3% 6 6.0, respectively), with no significant differences between groups (LVHI vs. EHVLI) in muscular strength (8.8% 6 3.1 vs. 6.7% 6 8.0, respectively) and 10-yard acceleration (2.2% 6 5.6 vs. 3.2% 6 5.6, respectively). For in-season RT of strength and power in collegiate American football players, all exercises performed should use evidence-based volume loads to optimize adaptations because a single exercise performed with extreme volume load may limit muscular strength and power development. [ABSTRACT FROM AUTHOR]

Consumer wearable technology use is widespread and there is a need to validate measures obtained in uncontrolled settings. Because no standard exists for the treatment of heart rate data during exercise, the effect of different approaches on reliability (Coefficient of Variation [CV], Intraclass Correlation Coefficient [ICC]) and validity (Mean Absolute Percent Error [MAPE], Lin's Concordance Correlation Coefficient [CCC)] were determined in the Polar Verity Sense and OH1 during trail running. The Verity Sense met the reliability (CV < 5%, ICC > 0.7) and validity thresholds (MAPE < 5%, CCC > 0.9) in all cases. The OH1 met reliability thresholds in all cases except entire session average (ICC = 0.57). The OH1 met the validity MAPE threshold in all cases (3.3–4.1%), but not CCC (0.6–0.86). Despite various heart rate data processing methods, the approach may not affect reliability and validity interpretation provided adequate data points are obtained. It is also possible that a large volume of data will artificially inflate metrics. [ABSTRACT FROM AUTHOR]

Research suggests that warm-ups which elicit a post activation potentiation (PAP) effect via high intensity muscular contractions may increase performance in subsequent activities requiring strength and power. Warm-up strategies designed to elicit a PAP may positively impact performance. The purpose of this investigation was to determine if a cycling warm-up that included a maximal overload would elicit a PAP effect and increase subsequent sprint cycling power output. Ten (age = 22 + 2yrs; mass = 75 + 15 kg;ht = 173 + 11 cm) recreationally trained athletic males (n = 7) and females (n = 3) participated in a with-in subjects design consisting of two randomly ordered sessions of sprint cycling on a bicycle ergometer with computer interface to assess power output. Two warm-up conditions were employed over two days. The standard warm-up condition consisted of a 4 minute stationary cycle ride with little resistance (1 kg) at a self-selected cadence. The overload warm-up condition consisted of the standard warm-up, plus an overload condition. That is, after the standard warm-up, in the overload condition subjects rested for 4-minutes while the weight basket was loaded to full capacity (10 kg). At 4 minutes, subjects pedaled the cycle as fast as possible. At maximal pedaling rpm, the weight basket was dropped manually, loading the cycle and starting a 10-second timer. In order to elicit complete fatigue (i.e. failure to pedal) within 8-10 seconds, the researcher pressed down as needed on the weight basket thereby increasing cycling resistance. After completing each individual warm-up condition, subjects then rested for 4-minutes, while 7.5% of the subject's body weight (kg) was loaded on the weight basket. At the 4-minute mark, subjects then pedaled the cycle as fast as possible. Once the subject reached 150 rpm (near maximal) on the cycle, the weight basket dropped, loading the cycle and starting a 10-second timer; the subject continued to pedal as hard as possible throughout the 10-second test. Paired Samples T-test was used to determine if there was a significant difference (p < 0.05) in power output between the two conditions. The results of this study demonstrated a significant increase (p < 0.05) in relative (W/kg) and absolute (Watts) power output (13.1 + 3.0 vs. 13.4 + 3.0 and 1002.0 + 273.4 vs. 1030.2 + 270.5, respectively) after subjects performed a maximal sprint cycle overload as compared to a standard warm-up. Despite an increase in power in the overload condition, no difference was observed in fatigue (percent power drop) between the two conditions. Data from this study suggests that the use of an overload sprint cycle warm-up may enhance activities where peak power output is required and needs to be maintained for short bouts. The coach may consider using this type of variation in overload during their dynamic, athletic warm-up to optimize performance in sports where peak and short-term power output are key components of competition. [ABSTRACT FROM AUTHOR]

The goal of this study was to test the role cellular senescence plays in the increased inflammation, chronic liver disease, and hepatocellular carcinoma seen in mice null for Cu/Zn‐Superoxide dismutase (Sod1KO). To inhibit senescence, wildtype (WT) and Sod1KO mice were given the senolytics, dasatinib, and quercetin (D + Q) at 6 months of age when the Sod1KO mice begin exhibiting signs of accelerated aging. Seven months of D + Q treatment reduced the expression of p16 in the livers of Sod1KO mice to WT levels and the expression of several senescence‐associated secretory phenotype factors (IL‐6, IL‐1β, CXCL‐1, and GDF‐15). D + Q treatment also reduced markers of inflammation in livers of the Sod1KO mice, for example, cytokines, chemokines, macrophage levels, and Kupffer cell clusters. D + Q treatment had no effect on various markers of liver fibrosis in the Sod1KO mice but reduced the expression of genes involved in liver cancer and dramatically reduced the incidence of hepatocellular carcinoma. Surprisingly, D + Q also reduced markers of necroptosis (phosphorylated and oligomerized MLKL) in the Sod1KO mice to WT levels. We also found that inhibiting necroptosis in the Sod1KO mice with necrostatin‐1s reduced the markers of cellular senescence (p16, p21, and p53). Our study suggests that an interaction occurs between cellular senescence and necroptosis in the liver of Sod1KO mice. We propose that these two cell fates interact through a positive feedback loop resulting in a cycle amplifying both cellular senescence and necroptosis leading to inflammaging and age‐associated pathology in the Sod1KO mice. [ABSTRACT FROM AUTHOR]

The inability to fully recover lost muscle mass following periods of disuse atrophy predisposes older adults to lost independence and poor quality of life. We have previously shown that mechanotherapy at a moderate load (4.5 N) enhances muscle mass recovery following atrophy in adult, but not older adult rats. We propose that elevated transverse stiffness in aged muscle inhibits the growth response to mechanotherapy and hypothesize that a higher load (7.6 N) will overcome this resistance to mechanical stimuli. F344/BN adult and older adult male rats underwent 14 days of hindlimb suspension, followed by 7 days of recovery with (RE + M) or without (RE) mechanotherapy at 7.6 N on gastrocnemius muscle. The 7.6 N load was determined by measuring transverse passive stiffness and linearly scaling up from 4.5 N. No differences in protein turnover or mean fiber cross-sectional area were observed between RE and RE + M for older adult rats or adult rats at 7.6 N. However, there was a higher number of small muscle fibers present in older adult, but not adult rats, which was explained by a 16-fold increase in the frequency of small fibers expressing embryonic myosin heavy chain. Elevated central nucleation, satellite cell abundance, and dystrophin-/laminin+ fibers were present in older adult rats only following 7.6 N, while 4.5 N did not induce damage at either age. We conclude that age is an important variable when considering load used during mechanotherapy and age-related transverse stiffness may predispose older adults to damage during the recovery period following disuse atrophy. [ABSTRACT FROM AUTHOR]

Abstract: This study presents an investigation on the possibility of improving the detection limit of bacteria with an inexpensive electrochemical, impedimetric sensor platform, by integrating the sensor with magnetic manipulation. The approach uses T4 bacteriophage coated Dynabeads to selectively capture and concentrate E. coli K12 cells from samples, to increase the sensitivity of detection at the surface of functionalized screen-printed carbon microarrays. Fluorescence and flow cytometry measurements indicate that the surface modification of the magnetic beads, with phages, and binding with the bacteria, were successful. Integration of the screen-printed carbon-based impedimetric sensor, with a magnetic manipulation system, was found to improve the sensitivity of the device, decreasing the limit of detection of E. coli K12 from 104 to 103 cfu/mL. We have also demonstrated that this approach provides for more specific detection of bacteria, enabling the operator to account for non-specific adsorption, and detection of bacteria in more complex (real) samples (milk). [Copyright &y& Elsevier]

A direct and efficient impedimetric method is presented for the detection of Bacillus anthracis Sterne vegetative cells, using Gamma phages as probes attached to screen-printed carbon electrode microarrays. The carbon electrodes were initially functionalized through cyclic-voltammetric reduction of a nitro-aryl diazonium moiety, followed by further reduction of nitro groups to amino groups, and finally by treatment with glutaraldehyde. Functionalization (probe immobilization) using Gamma phages was verified by XPS and TOF-SIM experiments. The Gamma phage-modified microarrays were then used to detect B. anthracis Sterne bacteria in aqueous electrolyte media. Faradaic impedimetric detection of bacteria in KCl solution containing the ferri/ferro cyanide redox couple shows a gradual increase in Z′ (real impedance) values, taken from the extrapolation of the linear portion of Nyquist plots in the low frequency range, for sensors placed in contact with increasing concentrations of B. anthracis. ΔZ′ values vary from 700 to 5300 Ohms for bacteria concentrations ranging from 102 to 108 cfu mL−1. These shifts in Z′ are attributed to a decrease in diffusion controlled charge transfer to the electrode surface following capture of intact B. anthracis. No significant ΔZ′ was observed for control experiments using E. coli. K12 as a non-specific target, even at a concentration of 108 cfu mL−1. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate here the possibility of designing semiconducting thin films with controlled electrochemical properties. The thin films are composed of (i) an insulating binder and (ii) a semiconductor nanopowder which enables the fine tuning of the semiconducting properties of the layers. Thus, p- and n-type silicon particles (obtained from a top-down technique), or metal-oxide ZnO, SnO2 and NiO nanoparticles (synthesized using a bottom-up protocol) are successfully integrated into spin-coated or screen-printed thin films and used as semiconducting materials. The flat band potential (Vfb) of the films is then easily tuned from 0V to −1.138V. [Copyright &y& Elsevier]

A novel method is presented for the specific and direct detection of bacteria using bacteriophages as recognition receptors immobilized covalently onto functionalized screen-printed carbon electrode (SPE) microarrays. The SPE networks were functionalized through electrochemical oxidation in acidic media of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) by applying a potential of +2.2 V to the working electrode. Immobilization of T4 bacteriophage onto the SPEs was achieved via EDC by formation of amide bonds between the protein coating of the phage and the electrochemically generated carboxylic groups at the carbon surface. The surface functionalizalion with EDC, and the binding of phages, was verified by time-of-fight secondary ion mass spectrometry. The immobilized T4 phages were then used to specifically detect E. coil bacteria. The presence of surface-bound bacteria was verified by scanning electron and fluorescence microscopies. Impedance measurements (Nyquist plots) show shifts of the order of 104 Ω due to the binding of E. coil bacteria to the T4 phages. No significant change in impedance was observed for control experiments using immobilized T4 phage in the presence of Salmonella. Impedance variations as a function of incubation time show a maximum shift after 20 min, indicating onset of lysis, as also confirmed by fluorescence microscopy. Concentration-response curves yield a detection limit of 104 cfu/mL for 50-μL samples. [ABSTRACT FROM AUTHOR]