1,855 research outputs found

    Whole body cryotherapy and recovery from exercise induced muscle damage: A systematic review

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    Introduction Cold therapies are used regularly in medicine for their analgesic and anti-inflammatory effects. Whole-body cryotherapy (WBC) involves exposure to air maintained between -110 and -160oC, and is hypothesised to reduce pain, local and systemic inflammation. WBC has recently become popular in an exercise and sporting context as a recovery method after skeletal muscle damage, however, research examining the efficacy of WBC in an athletic context is minimal. This review seeks to summarise the evidence for the effects of WBC on exercise recovery measures. Methods Electronic database searches were conducted from March to April 2013. Six large online databases were used; MEDLINE, SPORTDiscus, Scopus, Web of Science, PubMed and AMED. The search targeted human studies with an exercise task, and WBC intervention. Results included randomised controlled trials (RCT’s), uncontrolled trials and crossover designs. Results A total of 8 studies were included in the review. Two RCT’s, four crossover trials and two uncontrolled trials were identified. Five studies showed WBC had no effect on markers of muscle damage or inflammation post exercise, while 3 studies show a positive effect. Three out of the eight studies measured maximal muscle force production and subjective pain levels following exercise and WBC, with two showing WBC had a positive effect on muscle force recovery and pain. A meta-analysis was not conducted due to the heterogeneity of the studies. Conclusion The current evidence for the efficacy of WBC on exercise recovery is unclear. Published studies report mixed findings, and the study designs make these results difficult to interpret. As WBC is proposed as an aid to recovery in an athletic population, repeated measures of performance, muscle force production and pain are of importance to the athlete, however, are minimally reported in the literature. Cold water immersion (CWI) is widely used in an athletic setting for recovery, and has much literature supporting its use for the reduction of pain post-exercise. Well-designed RCT’s with controlled exercise interventions targeting performance measures are needed, in particular comparison of WBC with CWI data is needed for evaluation

    Effects of whole body cryotherapy and cold water immersion on immune and inflammatory markers following exercise induced muscle damage

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    Introduction: Cold therapies are used regularly in medicine for their analgesic and anti-inflammatory effects. Whole-body cryotherapy (WBC) involves exposure to air maintained between -110 and -160oC, and is hypothesised to reduce pain, local and systemic inflammation. WBC has recently become popular in an exercise and sporting context as a recovery method after skeletal muscle damage. However, research examining the efficacy of WBC in an athletic context is minimal, in particular, studies comparing WBC to currently accepted recovery methods are lacking. Cold water immersion (CWI) is a widely researched and applied method of skeletal muscle recovery in sport science. As yet, no study has compared the proposed new method of WBC and the currently practiced method of CWI. We have designed a randomised control trial to examine the efficacy of WBC, as compared with CWI on recovery from a bout of eccentric muscle damage. Methods: Sixty healthy male subjects will perform skeletal muscle function tests and an eccentric muscle damage protocol of their left quadriceps femoris, using an isokinetic dynamometer. They will then be randomly assigned to one of 3 groups, WBC, CWI or a passive recovery control (PAS). The WBC will expose subjects to -160°C for 3min, using cold air. The CWI condition involves whole body exposure for 3min, in water maintained at 12°C. The PAS will have subjects seated comfortably at room temperature following the exercise protocol. Blood samples, muscle functional measurements and pain reports will be taken before muscle damage, immediately following damage, prior to therapy administration and post therapy. Further follow up measures to be taken 6 h post, 24 h and 7 days post. Blood samples will be analysed for changes in interleukins 6, 8 and 10, creatine kinase and leukocyte population kinetics. Results: Testing is being conducted. Results to be presented at the international society of exercise immunology (ISEI) symposium in September 2013

    The Two-Handed Tile Assembly Model Is Not Intrinsically Universal

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    In this paper, we study the intrinsic universality of the well-studied Two-Handed Tile Assembly Model (2HAM), in which two “supertile” assemblies, each consisting of one or more unit-square tiles, can fuse together (self-assemble) whenever their total attachment strength is at least the global temperature τ. Our main result is that for all τ′ < τ, each temperature-τ′ 2HAM tile system cannot simulate at least one temperature-τ 2HAM tile system. This impossibility result proves that the 2HAM is not intrinsically universal, in stark contrast to the simpler abstract Tile Assembly Model which was shown to be intrinsically universal (The tile assembly model is intrinsically universal, FOCS 2012). On the positive side, we prove that, for every fixed temperature τ ≥ 2, temperature-τ 2HAM tile systems are intrinsically universal: for each τ there is a single universal 2HAM tile set U that, when appropriately initialized, is capable of simulating the behavior of any temperature τ 2HAM tile system. As a corollary of these results we find an infinite set of infinite hierarchies of 2HAM systems with strictly increasing power within each hierarchy. Finally, we show how to construct, for each τ, a temperature-τ 2HAM system that simultaneously simulates all temperature-τ 2HAM systems

    The Two-Handed Tile Assembly Model is not Intrinsically Universal

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    The Two-Handed Tile Assembly Model (2HAM) is a model of algorithmic self-assembly in which large structures, or assemblies of tiles, are grown by the binding of smaller assemblies. In order to bind, two assemblies must have matching glues that can simultaneously touch each other, and stick together with strength that is at least the temperature τ, where τ is some fixed positive integer. We ask whether the 2HAM is intrinsically universal. In other words, we ask: is there a single 2HAM tile set U which can be used to simulate any instance of the model? Our main result is a negative answer to this question. We show that for all τ′ < τ, each temperature-τ′ 2HAM tile system does not simulate at least one temperature-τ 2HAM tile system. This impossibility result proves that the 2HAM is not intrinsically universal and stands in contrast to the fact that the (single-tile addition) abstract Tile Assembly Model is intrinsically universal. On the positive side, we prove that, for every fixed temperature τ ≥ 2, temperature-τ 2HAM tile systems are indeed intrinsically universal. In other words, for each τ there is a single intrinsically universal 2HAM tile set U_τ that, when appropriately initialized, is capable of simulating the behavior of any temperature-τ 2HAM tile system. As a corollary, we find an infinite set of infinite hierarchies of 2HAM systems with strictly increasing simulation power within each hierarchy. Finally, we show that for each τ, there is a temperature-τ 2HAM system that simultaneously simulates all temperature-τ 2HAM systems

    Ni Mg mixed metal oxides for p-type dye-sensitized solar cells

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    Mg Ni mixed metal oxide photocathodes have been prepared by a mixed NiCl2/MgCl2 sol-gel process. The MgO/NiO electrodes have been extensively characterized using physical and electrochemical methods. Dye-sensitized solar cells have been prepared from these films and the higher concentrations of MgO improved the photovoltage of these devices, however, there was a notable drop in photocurrent with increasing Mg2+. Charge extraction and XPS experiments revealed that the cause of this was a positive shift in the energy of the valence band which decreased the driving force for electron transfer from the NiO film to the dye and therefore the photocurrent. In addition, increasing concentrations of MgO increases the volume of pores between 0.500 to 0.050 ÎĽm, while reducing pore volumes in the mesopore range (less than 0.050 ÎĽm) and lowering BET surface area from approximately 41 down to 30 m2 g-1. A MgO concentration of 5% was found to strike a balance between the increased photovoltage and decreased photocurrent, possessing a BET surface area of 35 m2 g-1 and a large pore volume in both the meso and macropore range, which lead to a higher overall power conversion efficiency than NiO alone

    Neonatal iron deficiency causes abnormal phosphate metabolism by elevating FGF23 in normal and ADHR mice.

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    Fibroblast growth factor 23 (FGF23) gain of function mutations can lead to autosomal dominant hypophosphatemic rickets (ADHR) disease onset at birth, or delayed onset following puberty or pregnancy. We previously demonstrated that the combination of iron deficiency and a knock-in R176Q FGF23 mutation in mature mice induced FGF23 expression and hypophosphatemia that paralleled the late-onset ADHR phenotype. Because anemia in pregnancy and in premature infants is common, the goal of this study was to test whether iron deficiency alters phosphate handling in neonatal life. Wild-type (WT) and ADHR female breeder mice were provided control or iron-deficient diets during pregnancy and nursing. Iron-deficient breeders were also made iron replete. Iron-deficient WT and ADHR pups were hypophosphatemic, with ADHR pups having significantly lower serum phosphate (p 50 fold; p < 0.01). WT and ADHR pups receiving low iron had elevated intact serum FGF23; ADHR mice were affected to a greater degree (p < 0.01). Iron-deficient mice also showed increased Cyp24a1 and reduced Cyp27b1, and low serum 1,25-dihydroxyvitamin D (1,25D). Iron repletion normalized most abnormalities. Because iron deficiency can induce tissue hypoxia, oxygen deprivation was tested as a regulator of FGF23, and was shown to stimulate FGF23 mRNA in vitro and serum C-terminal FGF23 in normal rats in vivo. These studies demonstrate that FGF23 is modulated by iron status in young WT and ADHR mice and that hypoxia independently controls FGF23 expression in situations of normal iron. Therefore, disturbed iron and oxygen metabolism in neonatal life may have important effects on skeletal function and structure through FGF23 activity on phosphate regulation

    Greater numbers of antral follicles in the ovary are associated with increased concentrations of glucose in uterine luminal fluid of beef heifers

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    Increased antral follicles are associated with greater fertility and a uterine environment that is more supportive of early embryonic development in beef heifers. Glucose is a primary energy source for embryos, and glucose concentrations are elevated in uterine luminal fluid (ULF) of pregnant heifers. We hypothesized that ULF glucose concentrations and endometrial transcript abundance for glucose transporters on d16 after insemination would be greater in heifers with increased numbers of antral follicles. Heifers classified with either increased or diminished antral follicle counts were artificially inseminated following the CO-Synch protocol (d0). On d16 after insemination, reproductive tracts of heifers were collected at an abattoir to retrieve conceptuses to determine pregnancy. Uterine luminal fluid was collected, endometrium was biopsied, total RNA was extracted and glucose transporter transcript abundances were determined. Data were analyzed using the MIXED procedure of SAS with antral follicle group, pregnancy status, and the interaction as fixed effects. Glucose concentrations in ULF were greater in heifers with increased antral follicle numbers. Glucose ULF concentrations increased in pregnant heifers. Facilitated glucose transporter member 1 (SLC2A1) transcript abundance was increased in the endometrium of pregnant heifers but was not different due to antral follicle number or the interaction. Differences in uterine concentrations of glucose associated with antral follicle number could be due to another mechanism, since glucose transporters were not different between antral follicle numbers. Therefore, heifers with increased number of antral follicles have increased energy availability in the uterus to support trophoblast proliferation and function

    Circulating αKlotho influences phosphate handling by controlling FGF23 production

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    The FGF23 coreceptor αKlotho (αKL) is expressed as a membrane-bound protein (mKL) that forms heteromeric complexes with FGF receptors (FGFRs) to initiate intracellular signaling. It also circulates as an endoproteolytic cleavage product of mKL (cKL). Previously, a patient with increased plasma cKL as the result of a translocation [t(9;13)] in the αKLOTHO (KL) gene presented with rickets and a complex endocrine profile, including paradoxically elevated plasma FGF23, despite hypophosphatemia. The goal of this study was to test whether cKL regulates phosphate handling through control of FGF23 expression. To increase cKL levels, mice were treated with an adeno-associated virus producing cKL. The treated groups exhibited dose-dependent hypophosphatemia and hypocalcemia, with markedly elevated FGF23 (38 to 456 fold). The animals also manifested fractures, reduced bone mineral content, expanded growth plates, and severe osteomalacia, with highly increased bone Fgf23 mRNA (>150 fold). cKL activity in vitro was specific for interactions with FGF23 and was FGFR dependent. These results demonstrate that cKL potently stimulates FGF23 production in vivo, which phenocopies the KL translocation patient and metabolic bone syndromes associated with elevated FGF23. These findings have important implications for the regulation of αKL and FGF23 in disorders of phosphate handling and biomineralization
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