ABSTRACTFragala, MS, Cadore, EL, Dorgo, S, Izquierdo, M, Kraemer, WJ, Peterson, MD, and Ryan, ED. Resistance training for older adultsposition statement from the national strength and conditioning ...association. J Strength Cond Res XX(X)000–000, 2019—Aging, even in the absence of chronic disease, is associated with a variety of biological changes that can contribute to decreases in skeletal muscle mass, strength, and function. Such losses decrease physiologic resilience and increase vulnerability to catastrophic events. As such, strategies for both prevention and treatment are necessary for the health and well-being of older adults. The purpose of this Position Statement is to provide an overview of the current and relevant literature and provide evidence-based recommendations for resistance training for older adults. As presented in this Position Statement, current research has demonstrated that countering muscle disuse through resistance training is a powerful intervention to combat the loss of muscle strength and muscle mass, physiological vulnerability, and their debilitating consequences on physical functioning, mobility, independence, chronic disease management, psychological well-being, quality of life, and healthy life expectancy. This Position Statement provides evidence to support recommendations for successful resistance training in older adults related to 4 parts(a) program design variables, (b) physiological adaptations, (c) functional benefits, and (d) considerations for frailty, sarcopenia, and other chronic conditions. The goal of this Position Statement is to a) help foster a more unified and holistic approach to resistance training for older adults, b) promote the health and functional benefits of resistance training for older adults, and c) prevent or minimize fears and other barriers to implementation of resistance training programs for older adults.
Renewable acrylonitrile production Karp, Eric M.; Eaton, Todd R.; Nogué, Violeta Sànchez i ...
Science,
12/2017, Letnik:
358, Številka:
6368
Journal Article
Recenzirano
Odprti dostop
Acrylonitrile (ACN) is a petroleum-derived compound used in resins, polymers, acrylics, and carbon fiber. We present a process for renewable ACN production using 3-hydroxypropionic acid (3-HP), which ...can be produced microbially from sugars. The process achieves ACN molar yields exceeding 90% from ethyl 3-hydroxypropanoate (ethyl 3-HP) via dehydration and nitrilation with ammonia over an inexpensive titanium dioxide solid acid catalyst. We further describe an integrated process modeled at scale that is based on this chemistry and achieves near-quantitative ACN yields (98 ± 2%) from ethyl acrylate. This endothermic approach eliminates runaway reaction hazards and achieves higher yields than the standard propylene ammoxidation process. Avoidance of hydrogen cyanide as a by-product also improves process safety and mitigates product handling requirements.
Integrative structural biology attempts to model the structures of protein complexes that are challenging or intractable by classical structural methods (due to size, dynamics, or heterogeneity) by ...combining computational structural modeling with data from experimental methods. One such experimental method is chemical crosslinking mass spectrometry (XL‐MS), in which protein complexes are crosslinked and characterized using liquid chromatography‐mass spectrometry to pinpoint specific amino acid residues in close structural proximity. The commonly used lysine‐reactive N‐hydroxysuccinimide ester reagents disuccinimidylsuberate (DSS) and bis(sulfosuccinimidyl)suberate (BS3) have a linker arm that is 11.4 Å long when fully extended, allowing Cα (alpha carbon of protein backbone) atoms of crosslinked lysine residues to be up to ∼24 Å apart. However, XL‐MS studies on proteins of known structure frequently report crosslinks that exceed this distance. Typically, a tolerance of ∼3 Å is added to the theoretical maximum to account for this observation, with limited justification for the chosen value. We used the Dynameomics database, a repository of high‐quality molecular dynamics simulations of 807 proteins representative of diverse protein folds, to investigate the relationship between lysine–lysine distances in experimental starting structures and in simulation ensembles. We conclude that for DSS/BS3, a distance constraint of 26–30 Å between Cα atoms is appropriate. This analysis provides a theoretical basis for the widespread practice of adding a tolerance to the crosslinker length when comparing XL‐MS results to structures or in modeling. We also discuss the comparison of XL‐MS results to MD simulations and known structures as a means to test and validate experimental XL‐MS methods.
Access to new endoscopic treatment modalities often depends on price. To resolve this gap and therefore help to ensure that care delivery can occur on a clinical basis, we aimed to establish the ...value to insurers of novel hemostatic powder to treat GI tumor bleeding.
A decision-analytic model developed to assess the impact of endoscopic intervention on the risk of 30-day readmission for GI bleeding from an insurer perspective was adapted to assess GI tumor bleeding with hemostatic powder or standard endoscopic therapy. Costs were derived from Medicare populations. Outcomes were derived from a recent multicenter randomized clinical trial.
Costs ranged from $651 to $1613 to treat upper GI tumor bleeding and from $531 to $1014 to treat lower GI tumor bleeding based on risk reduction in 30-day hospital readmission for recurrent bleeding. These valuations should represent medical device and incremental facility costs in addition to incremental physician and staff time.
Coverage for novel endoscopic hemostatic powder therapy seems cost-saving to insurers.
Citrulline is an increasingly common dietary supplement that is thought to enhance exercise performance by increasing nitric oxide production. In the last 5 years, several studies have investigated ...the effects of citrulline supplements on strength and power outcomes, with mixed results reported. To date, the current authors are unaware of any attempts to systematically review this emerging body of literature.
The current study sought to conduct a systematic review and meta-analysis of the literature describing the effects of citrulline supplementation on strength and power outcomes.
A comprehensive, systematic search of three prominent research databases was performed to find peer-reviewed, English language, original research studies evaluating the effects of citrulline supplementation on indices of high-intensity exercise performance in healthy men and women. Outcomes included strength and power variables from performance tests involving multiple repetitive muscle actions of large muscle groups, consisting of either resistance training sets or sprints lasting 30 s or less. Tests involving isolated actions of small muscle groups or isolated attempts of single-jump tasks were not included for analysis due to differences in metabolic requirements. Studies were excluded from consideration if they lacked a placebo condition for comparison, were carried out in clinical populations, provided a citrulline dose of less than 3 g, provided the citrulline dose less than 30 min prior to exercise testing, or combined the citrulline ingredient with creatine, caffeine, nitrate, or other ergogenic ingredients.
Twelve studies, consisting of 13 total independent samples (n = 198 participants), met the inclusion criteria. Between-study variance, heterogeneity, and inconsistency across studies were low (Cochrane's Q = 6.9, p = 0.86; τ
= 0.0 0.0, 0.08, I
= 0.0 0.0, 40.0), and no funnel plot asymmetry was present. Results of the meta-analysis identified a significant benefit for citrulline compared to placebo treatments (p = 0.036), with a small pooled standardized mean difference (SMD; Hedges' G) of 0.20 (95% confidence interval 0.01-0.39).
The effect size was small (0.20), and confidence intervals for each individual study crossed the line of null effect. However, the results may be relevant to high-level athletes, in which competitive outcomes are decided by small margins. Further research is encouraged to fully elucidate the effects of potential moderating study characteristics, such as the form of citrulline supplement, citrulline dose, sex, age, and strength versus power tasks.
INTRODUCTIONThe purposes of this study were to investigate the age-related differences in absolute and normalized plantarflexion rate of torque development (RTD) at early (0–50 ms) and late (100–200 ...ms) time intervals and to examine specific neural and muscular mechanisms contributing to these differences.
METHODSThirty-two young (20.0 ± 2.1 yr) and 20 older (69.5 ± 3.3 yr) recreationally active men performed rapid plantarflexion isometric muscle actions to examine absolute and normalized RTD and muscle activation using EMG at early and late time intervals. Ultrasonography was used to examine medial gastrocnemius muscle size, echo intensity (EI), and muscle architecture (fascicle length FL and pennation angle PA).
RESULTSThe older men were weaker (23.9%, P < 0.001) and had lower later absolute and normalized RTD (P = 0.001–0.034) variables when compared with the young men. The older men also had higher EI (P < 0.001), smaller PA (P = 0.004), and lower later EMG amplitude values (P = 0.009–0.046). However, there were no differences in early RTD and EMG amplitude values, muscle size, or FL between groups (P = 0.097–0.914). Lower late RTD values were related to higher EI, smaller PA, and lower EMG amplitude values (r = −0.28–0.59, P = 0.001–0.044); however, late RTD values were no longer related to PA after normalizing to peak torque.
CONCLUSIONSAge-related alterations in muscle quality (EI), architecture, and muscle activation may influence rapid torque production at late time intervals (≥100 ms) from contraction onset. These findings highlight specific neuromuscular factors that influence the age-related reductions in RTD, which has been shown to significantly influence function and performance in older adults.
Polymeric components manufactured via freeform fabrication (FFF) typically have poor inter-laminar toughness resulting from incomplete bonding across layers during production. Here we study the ...effect of printing and post-processing on the inter-laminar toughness of additively manufactured semi-crystalline (poly-lactide (PLA)) structures. Specimens were subject to post-print thermal annealing to promote inter-laminar bonding, while post-annealing quenching rates were chosen to vary the induced degree of crystallinity in the final structure, as characterized via dynamic scanning calorimetry (DSC). Critical elastic-plastic strain energy release rates (JIc) of annealed samples were evaluated using the single edge notched bend (SENB) geometry and post-testing fractography. The results show that as-printed PLA adopts an amorphous character with good inter-laminar toughness and ductility. Post-print annealing can double the toughness via increased interfacial wetting, but only if the material is quenched rapidly to preserve the amorphous character. In contrast, post-print annealing followed by slow cooling results in a semi-crystalline state (≈25% crystallinity) with low fracture toughness and brittle fracture behavior.
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•Inter-layer fracture toughness of an additively manufactured semi-crystalline polymer is highly sensitive to processing.•As-printed parts have low crystallinity and moderate interfacial wetting, leading to moderate fracture toughness.•Post-print annealing increases toughness via wetting, if the part is quenched after annealing to maintain low crystallinity.•Slow-cooling after annealing results in adequate wetting but high crystallinity, resulting in poor interlayer toughness.
White matter (WM) neuroplasticity in the human brain has been tracked non-invasively using advanced magnetic resonance imaging techniques, with increasing evidence for improved axonal transmission ...efficiency as a central mechanism. The current study is the culmination of a series of studies, which characterized the structure-function relationship of WM transmission efficiency in the cortico-spinal tract (CST) during motor learning. Here, we test the hypothesis that increased transmission efficiency is linked directly to increased myelination using myelin water imaging (MWI). MWI was used to evaluate neuroplasticity-related improvements in the CST. The MWI findings were then compared to diffusion tensor imaging (DTI) results, with the secondary hypothesis that radial diffusivity (RD) would have a stronger relationship than axial diffusivity (AD) if the changes were due to increased myelination. Both MWI and RD data showed the predicted pattern of significant results, strongly supporting that increased myelination plays a central role in WM neuroplasticity.
Construction and characterization of large genetic variant libraries is essential for understanding genome function, but remains challenging. Here, we introduce a Cas9-based approach for generating ...pools of mutants with defined genetic alterations (deletions, substitutions, and insertions) with an efficiency of 80-100% in yeast, along with methods for tracking their fitness en masse. We demonstrate the utility of our approach by characterizing the DNA helicase SGS1 with small tiling deletion mutants that span the length of the protein and a series of point mutations against highly conserved residues in the protein. In addition, we created a genome-wide library targeting 315 poorly characterized small open reading frames (smORFs, <100 amino acids in length) scattered throughout the yeast genome, and assessed which are vital for growth under various environmental conditions. Our strategy allows fundamental biological questions to be investigated in a high-throughput manner with precision.
Home-based dialysis modalities offer both clinical and practical advantages to patients. The use of the home-based modalities, peritoneal dialysis and home hemodialysis, has been increasing over the ...past decade after a long period of decline. Given the increasing frequency of use of these types of dialysis, it is important for clinicians to be familiar with how these types of dialysis are performed and key clinical aspects of care related to their use in patients with end-stage kidney disease.
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