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The preservation of skeletal muscle mass and strength with advancing age are, we propose, critical aspects of ageing with health and vitality. Physical inactivity and poor nutrition are known to accelerate the gradual age-related decline in muscle mass and strength-sarcopenia-however, both are subject to modification. The main purpose of this review is to present the latest, evidence-based recommendations for physical activity and exercise, as well as diet for older adults that would help in preserving muscle mass and strength. We take the position that future physical activity/exercise guidelines need to make specific reference to resistance exercise and highlight the benefits of higher-intensity aerobic exercise training, alongside advocating older adults perform aerobic-based physical activity and household tasks (e.g., carrying groceries). In terms of dietary recommendations, greater emphasis should be placed on optimal rather than minimum protein intakes for older adults. Indeed, guidelines that endorse a daily protein intake of 1.2-1.5 g/kg BM/day, which are levels 50-90 % greater than the current protein Recommendation Dietary Allowance (0.8 g/kg BM/day), are likely to help preserve muscle mass and strength and are safe for healthy older adults. Being cognisant of factors (e.g., reduced appetite) that may preclude older adults from increasing their total daily protein intake, we echo the viewpoint of other active researchers in advocating that protein recommendations for older adults be based on a per meal approach in order to maximize muscle protein synthesis (MPS). On this basis, assuming three meals are consumed daily, a protein dose of 0.4-0.5 g/kg BM should be contained in each meal. We are beginning to understand ways in which to increase the utilization of ingested protein for the stimulation of MPS, namely by increasing the proportion of leucine contained in a given dose of protein, co-ingesting other nutrients (e.g., carbohydrate and fat or supplementation with n-3 polyunsaturated fatty acids) or being physically active prior to protein intake. Clearly, developing simple lifestyle interventions targeted at preserving muscle mass and strength with advancing age is crucial for facilitating longer, healthier lives into older age.

Due to improved health care, diet and infrastructure in developed countries, since 1840 life expectancy has increased by approximately 2 years per decade. Accordingly, by 2050, a quarter of Europe's population will be over 65 years, representing a 10 % rise in half a century. With this rapid rise comes an increased prevalence of diseases of ageing and associated healthcare expenditure. To address the health consequences of global ageing, research in model systems (worms, flies and mice) has indicated that reducing the rate of organ growth, via reductions in protein synthetic rates, has multi-organ health benefits that collectively lead to improvements in lifespan. In contrast, human pre-clinical, clinical and large cohort prospective studies demonstrate that ageing leads to anabolic (i.e. growth) impairments in skeletal muscle, which in turn leads to reductions in muscle mass and strength, factors directly associated with mortality rates in the elderly. As such, increasing muscle protein synthesis via exercise or protein-based nutrition maintains a strong, healthy muscle mass, which in turn leads to improved health, independence and functionality. The aim of this review is to critique current literature relating to the maintenance of muscle mass across lifespan and discuss whether maintaining or reducing protein synthesis is the most logical approach to support musculoskeletal function and by extension healthy human ageing.

The ubiquitous transcriptional coactivators Yap (gene symbol Yap1) and Taz (gene symbol Wwtr1) regulate gene expression mainly by coactivating the Tead transcription factors. Being at the center of the Hippo signaling network, Yap and Taz are regulated by the Hippo kinase cassette and additionally by a plethora of exercise-associated signals and signaling modules. These include mechanotransduction, the AKT-mTORC1 network, the SMAD transcription factors, hypoxia, glucose homeostasis, AMPK, adrenaline/epinephrine and angiotensin II through G protein-coupled receptors, and IL-6. Consequently, exercise should alter Hippo signaling in several organs to mediate at least some aspects of the organ-specific adaptations to exercise. Indeed, Tead1 overexpression in muscle fibers has been shown to promote a fast-to-slow fiber type switch, whereas Yap in muscle fibers and cardiomyocytes promotes skeletal muscle hypertrophy and cardiomyocyte adaptations, respectively. Finally, genome-wide association studies in humans have linked the Hippo pathway members LATS2, TEAD1, YAP1, VGLL2, VGLL3, and VGLL4 to body height, which is a key factor in sports., (Copyright © 2016 the American Physiological Society.)

Using an amalgamation of previously studied "train-low" paradigms, we tested the effects of reduced carbohydrate (CHO) but high leucine availability on cell-signaling responses associated with exercise-induced regulation of mitochondrial biogenesis and muscle protein synthesis (MPS). In a repeated-measures crossover design, 11 males completed an exhaustive cycling protocol with high CHO availability before, during, and after exercise (HIGH) or alternatively, low CHO but high protein (leucine enriched) availability (LOW + LEU). Muscle glycogen was different (P < 0.05) pre-exercise (HIGH: 583 ± 158, LOW + LEU: 271 ± 85 mmol kg(-1) dw) but decreased (P < 0.05) to comparable levels at exhaustion (≈100 mmol kg(-1) dw). Despite differences (P < 0.05) in exercise capacity (HIGH: 158 ± 29, LOW + LEU: 100 ± 17 min), exercise induced (P < 0.05) comparable AMPKα2 (3-4-fold) activity, PGC-1α (13-fold), p53 (2-fold), Tfam (1.5-fold), SIRT1 (1.5-fold), Atrogin 1 (2-fold), and MuRF1 (5-fold) gene expression at 3 h post-exercise. Exhaustive exercise suppressed p70S6K activity to comparable levels immediately post-exercise (≈20 fmol min(-1) mg(-1)). Despite elevated leucine availability post-exercise, p70S6K activity remained suppressed (P < 0.05) 3 h post-exercise in LOW + LEU (28 ± 14 fmol min(-1) mg(-1)), whereas muscle glycogen resynthesis (40 mmol kg(-1) dw h(-1)) was associated with elevated (P < 0.05) p70S6K activity in HIGH (53 ± 30 fmol min(-1) mg(-1)). We conclude: (1) CHO restriction before and during exercise induces "work-efficient" mitochondrial-related cell signaling but; (2) post-exercise CHO and energy restriction maintains p70S6K activity at basal levels despite feeding leucine-enriched protein. Our data support the practical concept of "fuelling for the work required" as a potential strategy for which to amalgamate train-low paradigms into periodized training programs., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

Fish oil (FO) supplementation potentiates muscle protein synthesis (MPS) in response to a hyperaminoacidemic-hyperinsulinemic infusion. Whether FO supplementation potentiates MPS in response to protein ingestion or when protein ingestion is combined with resistance exercise (RE) remains unknown. In a randomized, parallel group design, 20 healthy males were randomized to receive 5 g/day of either FO or coconut oil control (CO) for 8 weeks. After supplementation, participants performed a bout of unilateral RE followed by ingestion of 30 g of whey protein. Skeletal muscle biopsies were obtained before and after supplementation for assessment of muscle lipid composition and relevant protein kinase activities. Infusion of L-[ring-(13)C6] phenylalanine was used to measure basal myofibrillar MP Sat rest (REST), in a nonexercised leg following protein ingestion (FED) and following RE and protein ingestion (FEDEX).MPS was significantly elevated above REST during FEDEX in both the FO and CO groups, but there was no effect of supplementation. There was a significant increase in MPS in both groups above REST during FED but no effect of supplementation. Supplementation significantly decreased pan PKB activity at RESTin the FO group but not the CO group. There was a significant increase from REST at post-RE for PKB and AMPKα2 activity in the CO group but not in the FO group. In FEDEX, there was a significant increase in p70S6K1 activity from REST at 3 h in the CO group only. These data highlight that 8 weeks of FO supplementation alters kinase signaling activity in response to RE plus protein ingestion without influencing MPS., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

Skeletal muscle is a plastic tissue capable of adapting and mal-adapting to physical activity and diet. The response of skeletal muscle to adaptive stimuli, such as exercise, can be modified by the prior nutritional status of the muscle. The influence of nutrition on skeletal muscle has the potential to substantially impact physical function and whole body metabolism. Animal and cell based models show that omega-3 fatty acids, in particular those of marine origin, can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that omega-3 fatty acids of marine origin can influence the exercise and nutritional response of skeletal muscle. These studies show that the prior omega-3 status influences not only the metabolic response of muscle to nutrition, but also the functional response to a period of exercise training. Omega-3 fatty acids of marine origin therefore have the potential to alter the trajectory of a number of human diseases including the physical decline associated with aging. We explore the potential molecular mechanisms by which omega-3 fatty acids may act in skeletal muscle, considering the n-3/n-6 ratio, inflammation and lipidomic remodelling as possible mechanisms of action. Finally, we suggest some avenues for further research to clarify how omega-3 fatty acids may be exerting their biological action in skeletal muscle.

Although dispositional inferences may be consciously drawn from the trait implications of observed behavior, abundant research has shown that people also spontaneously infer trait dispositions simply in the process of comprehending behavior. These spontaneous trait inferences (STIs) can occur without intention or awareness. All research on STIs has studied STIs based on behaviors of individual persons. Yet important aspects of social life occur in groups, and people regularly perceive groups engaging in coordinated action. We propose that perceivers make spontaneous trait inferences about groups (STIGs), parallel to the STIs formed about individuals. In 5 experiments we showed that (a) perceivers made STIGs comparable with STIs about individuals (based on the same behaviors), (b) a cognitive load manipulation did not affect the occurrence of STIGs, (c) STIGs occurred for groups varying in entitativity, (d) STIGs influenced perceivers' impression ratings of those groups, and (e) STIG-based group impressions generalized to new group members. These experiments provide the first evidence for STIGs, a process that may contribute to the formation of spontaneous group impressions. Implications for stereotype formation are discussed., ((c) 2015 APA, all rights reserved).)

We examined how the stimulatory effect of leucine on the mechanistic target of rapamycin complex 1 (mTORC1) pathway is affected by the presence of the remaining essential amino acids (EAAs). Nine male subjects performed resistance exercise on 4 occasions and were randomly supplied EAAs with leucine, EAAs without leucine (EAA-Leu), leucine alone, or flavored water (placebo; control). Muscle biopsies were taken from the vastus lateralis before and 60 and 90 min after exercise. Biopsies were analyzed for protein phosphorylation, kinase activity, protein-protein interactions, amino acid concentrations, and tracer incorporation. Leucine alone stimulated ribosomal protein s6 kinase 1 (S6K1) phosphorylation ∼280% more than placebo and EAA-Leu after exercise. Moreover, this response was enhanced by 60-75% after intake of EAAs compared with that of leucine alone (P < 0.05). Kinase activity of S6K1 reflected that of S6K1 phosphorylation; 60 min after exercise, the activity was elevated 3.3- and 4.2-fold with intake of leucine alone and with EAAs, respectively (P < 0.05). The interaction between mammalian target of rapamycin and regulatory-associated protein of mammalian target of rapamycin was unaltered in response to both resistance exercise and amino acid provision. Leucine alone stimulates mTORC1 signaling, although this response is enhanced by other EAAs and does not appear to be caused by alterations in mTORC1 assembly., (© FASEB.)

Glucose hypometabolism and impaired mitochondrial function in neurons have been suggested to play early and perhaps causative roles in Alzheimer's disease (AD) pathogenesis. Activity of the aspartic acid protease, beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), responsible for beta amyloid peptide generation, has recently been demonstrated to modify glucose metabolism. We therefore examined, using a human neuroblastoma (SH-SY5Y) cell line, whether increased BACE1 activity is responsible for a reduction in cellular glucose metabolism. Overexpression of active BACE1, but not a protease-dead mutant BACE1, protein in SH-SY5Y cells reduced glucose oxidation and the basal oxygen consumption rate, which was associated with a compensatory increase in glycolysis. Increased BACE1 activity had no effect on the mitochondrial electron transfer process but was found to diminish substrate delivery to the mitochondria by inhibition of key mitochondrial decarboxylation reaction enzymes. This BACE1 activity-dependent deficit in glucose oxidation was alleviated by the presence of beta hydroxybutyrate or α-lipoic acid. Consequently our data indicate that raised cellular BACE1 activity drives reduced glucose oxidation in a human neuronal cell line through impairments in the activity of specific tricarboxylic acid cycle enzymes. Because this bioenergetic deficit is recoverable by neutraceutical compounds we suggest that such agents, perhaps in conjunction with BACE1 inhibitors, may be an effective therapeutic strategy in the early-stage management or treatment of AD.

The present study aimed to investigate the role of the mechanistic target of rapamycin complex 1 (mTORC1) in the regulation of myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis following endurance exercise. Forty-two female C57BL/6 mice performed 1 h of treadmill running (18 m min(-1) ; 5° grade), 1 h after i.p. administration of rapamycin (1.5 mg · kg(-1) ) or vehicle. To quantify skeletal muscle protein fractional synthesis rates, a flooding dose (50 mg · kg(-1) ) of l-[ring-(13) C6 ]phenylalanine was administered via i.p. injection. Blood and gastrocnemius muscle were collected in non-exercised control mice, as well as at 0.5, 3 and 6 h after completing exercise (n = 4 per time point). Skeletal muscle MyoPS and MitoPS were determined by measuring isotope incorporation in their respective protein pools. Activation of the mTORC1-signalling cascade was measured via direct kinase activity assay and immunoblotting, whereas genes related to mitochondrial biogenesis were measured via a quantitative RT-PCR. MyoPS increased rapidly in the vehicle group post-exercise and remained elevated for 6 h, whereas this response was transiently blunted (30 min post-exercise) by rapamycin. By contrast, MitoPS was unaffected by rapamycin, and was increased over the entire post-exercise recovery period in both groups (P < 0.05). Despite rapid increases in both MyoPS and MitoPS, mTORC1 activation was suppressed in both groups post-exercise for the entire 6 h recovery period. Peroxisome proliferator activated receptor-γ coactivator-1α, pyruvate dehydrogenase kinase 4 and mitochondrial transcription factor A mRNA increased post-exercise (P < 0.05) and this response was augmented by rapamycin (P < 0.05). Collectively, these data suggest that endurance exercise stimulates MyoPS and MitoPS in skeletal muscle independently of mTORC1 activation., (© 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.)

Two studies investigated how people define and perceive diversity in the historically majority-group dominated contexts of business and academia. We hypothesized that individuals construe diversity as both the numeric representation of racial minorities and the social acceptance of racial minorities within a group. In Study 1, undergraduates' (especially minorities') perceptions of campus diversity were predicted by perceived social acceptance on a college campus, above and beyond perceived minority representation. Study 2 showed that increases in a company's representation and social acceptance independently led to increases in perceived diversity of the company among Whites. Among non-Whites, representation and social acceptance only increased perceived diversity of the company when both qualities were high. Together these findings demonstrate the importance of both representation and social acceptance to the achievement of diversity in groups and that perceiver race influences the relative importance of these two components of diversity., (© 2015 by the Society for Personality and Social Psychology, Inc.)

Combining endurance and strength training in the same session has been reported to reduce the anabolic response to the latter form of exercise. The underlying mechanism, based primarily on results from rodent muscle, is proposed to involve AMPK-dependent inhibition of mTORC1 signaling. This hypothesis was tested in eight trained male subjects who in randomized order performed either resistance exercise only (R) or interval cycling followed by resistance exercise (ER). Biopsies taken from the vastus lateralis before and after endurance exercise and repeatedly after resistance exercise were assessed for glycogen content, kinase activity, protein phosphorylation, and gene expression. Mixed muscle fractional synthetic rate was measured at rest and during 3 h of recovery using the stable isotope technique. In ER, AMPK activity was elevated immediately after both endurance and resistance exercise (∼90%, P < 0.05) but was unchanged in R. Thr(389) phosphorylation of S6K1 was increased severalfold immediately after exercise (P < 0.05) in both trials and increased further throughout recovery. After 90 and 180 min recovery, S6K1 activity was elevated (∼55 and ∼110%, respectively, P < 0.05) and eukaryotic elongation factor 2 phosphorylation was reduced (∼55%, P < 0.05) with no difference between trials. In contrast, markers for protein catabolism were differently influenced by the two modes of exercise; ER induced a significant increase in gene and protein expression of MuRF1 (P < 0.05), which was not observed following R exercise only. In conclusion, cycling-induced elevation in AMPK activity does not inhibit mTOR complex 1 signaling after subsequent resistance exercise but may instead interfere with the hypertrophic response by influencing key components in protein breakdown., (Copyright © 2015 the American Physiological Society.)

Race and gender categories, although long presumed to be perceived independently, are inextricably tethered in social perception due in part to natural confounding of phenotypic cues. We predicted that target gender would affect race categorizations. Consistent with this hypothesis, feminine faces compelled White categorizations, and masculine faces compelled Asian or Black categorizations of racially ambiguous targets (Study 1), monoracial targets (Study 2), and real facial photographs (Study 3). The efficiency of judgments varied concomitantly. White categorizations were rendered more rapidly for feminine, relative to masculine faces, but the opposite was true for Asian and Black categorizations (Studies 1-3). Moreover, the effect of gender on categorization efficiency was compelled by racial phenotypicality for Black targets (Study 3). Finally, when targets' race prototypicality was held constant, gender still influenced race categorizations (Study 4). These findings indicate that race categorizations are biased by presumably unrelated gender cues., (© 2015 by the Society for Personality and Social Psychology, Inc.)

Concurrent training (the combination of endurance exercise to resistance training) is a common practice for athletes looking to maximise strength and endurance. Over 20 years ago, it was first observed that performing endurance exercise after resistance exercise could have detrimental effects on strength gains. At the cellular level, specific protein candidates have been suggested to mediate this training interference; however, at present, the physiological reason(s) behind the concurrent training effect remain largely unknown. Even less is known regarding the optimal nutritional strategies to support concurrent training and whether unique nutritional approaches are needed to support endurance and resistance exercise during concurrent training approaches. In this review, we will discuss the importance of protein supplementation for both endurance and resistance training adaptation and highlight additional nutritional strategies that may support concurrent training. Finally, we will attempt to synergise current understanding of the interaction between physiological responses and nutritional approaches into practical recommendations for concurrent training.

Antimicrobial efficacy against Lawsonia intracellularis is difficult to evaluate in vitro, thus, the effects of gallium maltolate's (GaM) were investigated in a rabbit model for equine proliferative enteropathy (EPE). Juvenile (5-6-week-old) does were infected with 3.0 × 10(8) L. intracellularis/rabbit and allocated into three groups (n = 8). One week postinfection, one group was treated with GaM, 50 mg/kg; one, with doxycycline, 5 mg/kg; and one with a sham-treatment (control). Feces and blood were collected daily and weekly, respectively, to verify presence of L. intracellularis fecal shedding using qPCR, and seroconversion using immunoperoxidase monolayer assay. Rabbits were sacrificed after 1 week of treatment to collect intestinal tissues focusing on EPE-affected sections. Intestinal lesions were confirmed via immunohistochemistry. No difference was noted between treatments regarding EPE-lesions in jejunum (P = 0.51), ileum (P = 0.74), and cecum (P = 0.35), or in L. intracellularis fecal shedding (P = 0.64). GaM and doxycycline appear to have similar efficacy against EPE in infected rabbits., (© 2014 John Wiley & Sons Ltd.)

Skeletal muscle sirtuin 1 (SIRT1) expression is reduced under insulin-resistant conditions, such as those resulting from high-fat diet (HFD) feeding and obesity. Herein, we investigated whether constitutive activation of SIRT1 in skeletal muscle prevents HFD-induced muscle insulin resistance. To address this, mice with muscle-specific overexpression of SIRT1 (mOX) and wild-type (WT) littermates were fed a control diet (10% calories from fat) or HFD (60% of calories from fat) for 12 wk. Magnetic resonance imaging and indirect calorimetry were used to measure body composition and energy expenditure, respectively. Whole body glucose metabolism was assessed by oral glucose tolerance test, and insulin-stimulated glucose uptake was measured at a physiological insulin concentration in isolated soleus and extensor digitorum longus muscles. Although SIRT1 was significantly overexpressed in muscle of mOX vs. WT mice, body weight and percent body fat were similarly increased by HFD for both genotypes, and energy expenditure was unaffected by diet or genotype. Importantly, impairments in glucose tolerance and insulin-mediated activation of glucose uptake in skeletal muscle that occurred with HFD feeding were not prevented in mOX mice. In contrast, mOX mice showed enhanced postischemic cardiac functional recovery compared with WT mice, confirming the physiological functionality of the SIRT1 transgene in this mouse model. Together, these results demonstrate that activation of SIRT1 in skeletal muscle alone does not prevent HFD-induced glucose intolerance, weight gain, or insulin resistance.

Oral gallium maltolate (GaM) pharmacokinetics (PK) and intestinal tissue (IT) concentrations of elemental gallium ([Ga]) and iron ([Fe]) were investigated in a rabbit model of equine proliferative enteropathy (EPE). New Zealand white does (uninfected controls and EPE-infected, n = 6/group) were given a single oral GaM dose (50 mg/kg). Serial blood samples were collected from 0 to 216 h post-treatment (PT) and IT samples after euthanasia. Serology, qPCR, and immunohistochemistry confirmed, or excluded, EPE. Blood and IT [Ga] and [Fe] were determined using inductively coupled plasma-mass spectrometry. PK parameters were estimated through noncompartmental approaches. For all statistical comparisons on [Ga] and [Fe] α = 5%. The Ga log-linear terminal phase rate constant was lower in EPE rabbits vs. uninfected controls [0.0116 ± 0.004 (SD) vs. 0.0171 ± 0.0028 per hour; P = 0.03]; but half-life (59.4 ± 24.0 vs. 39.4 ± 10.8 h; P = 0.12); Cmax (0.50 ± 0.21 vs. 0.59 ± 0.42 μg/mL; P = 0.45); tmax (1.75 ± 0.41 vs. 0.9 ± 0.37 h; P = 0.20); and oral clearance (6.743 ± 1.887 vs. 7.208 ± 2.565 L/h; P = 0.74) were not. IT's [Ga] and [Fe] were higher (P < 0.0001) in controls. In conclusion, although infection reduces IT [Ga] and [Fe], a 48 h GaM dosing interval is appropriate for multidose studies in EPE rabbits., (© 2014 John Wiley & Sons Ltd.)

The goal of the current work was to profile positive (mTORC1 activation, autocrine/paracrine growth factors) and negative [AMPK, unfolded protein response (UPR)] pathways that might regulate overload-induced mTORC1 (mTOR complex 1) activation with the hypothesis that a number of negative regulators of mTORC1 will be engaged during a supraphysiological model of hypertrophy. To achieve this, mTORC1-IRS-1/2 signaling, BiP/CHOP/IRE1α, and AMPK activation were determined in rat plantaris muscle following synergist ablation (SA). SA resulted in significant increases in muscle mass of ~4% per day throughout the 21 days of the experiment. The expression of the insulin-like growth factors (IGF) were high throughout the 21st day of overload. However, IGF signaling was limited, since IRS-1 and -2 were undetectable in the overloaded muscle from day 3 to day 9. The decreases in IRS-1/2 protein were paralleled by increases in GRB10 Ser(501/503) and S6K1 Thr(389) phosphorylation, two mTORC1 targets that can destabilize IRS proteins. PKB Ser(473) phosphorylation was higher from 3-6 days, and this was associated with increased TSC2 Thr(939) phosphorylation. The phosphorylation of TSC2 (Thr1345) (an AMPK site) was also elevated, whereas phosphorylation at the other PKB site, Thr(1462), was unchanged at 6 days. In agreement with the phosphorylation of Thr(1345), SA led to activation of AMPKα1 during the initial growth phase, lasting the first 9 days before returning to baseline by day 12. The UPR markers CHOP and BiP were elevated over the first 12 days following ablation, whereas IRE1α levels decreased. These data suggest that during supraphysiological muscle loading at least three potential molecular brakes engage to downregulate mTORC1., (Copyright © 2014 the American Physiological Society.)

Aims/hypothesis: Impaired glucose uptake in skeletal muscle is an important contributor to glucose intolerance in type 2 diabetes. The aspartate protease, beta-site APP-cleaving enzyme 1 (BACE1), a critical regulator of amyloid precursor protein (APP) processing, modulates in vivo glucose disposal and insulin sensitivity in mice. Insulin-independent pathways to stimulate glucose uptake and GLUT4 translocation may offer alternative therapeutic avenues for the treatment of diabetes. We therefore addressed whether BACE1 activity, via APP processing, in skeletal muscle modifies glucose uptake and oxidation independently of insulin., Methods: Skeletal muscle cell lines were used to investigate the effects of BACE1 and α-secretase inhibition and BACE1 and APP overexpression on glucose uptake, GLUT4 cell surface translocation, glucose oxidation and cellular respiration., Results: In the absence of insulin, reduction of BACE1 activity increased glucose uptake and oxidation, GLUT4myc cell surface translocation, and basal rate of oxygen consumption. In contrast, overexpressing BACE1 in C2C12 myotubes decreased glucose uptake, glucose oxidation and oxygen consumption rate. APP overexpression increased and α-secretase inhibition decreased glucose uptake in C2C12 myotubes. The increase in glucose uptake elicited by BACE1 inhibition is dependent on phosphoinositide 3-kinase (PI3K) and mimicked by soluble APPα (sAPPα)., Conclusions/interpretation: Inhibition of muscle BACE1 activity increases insulin-independent, PI3K-dependent glucose uptake and cell surface translocation of GLUT4. As APP overexpression raises basal glucose uptake, and direct application of sAPPα increases PI3K-protein kinase B signalling and glucose uptake in myotubes, we suggest that α-secretase-dependent shedding of sAPPα regulates insulin-independent glucose uptake in skeletal muscle.

The aim of this study was to examine changes in the lipid profile of red blood cells and muscle tissue along with the expression of anabolic signalling proteins in human skeletal muscle. Following a 2-week control period, 10 healthy male participants consumed 5 g d(-1) of fish oil (FO) for 4 weeks. Muscle biopsies and venous blood samples were collected in the fasted state 2 weeks prior (W-2) and immediately before (W0) the initiation of FO supplementation for internal control. Muscle biopsies and venous blood samples were again obtained at week 1 (W1), 2 (W2) and 4 (W4) during FO supplementation for assessment of changes in lipid composition and expression of anabolic signalling proteins. There was no change in the composition of any lipid class between W-2 and W0 confirming control. Following FO supplementation n-3 polyunsaturated fatty acid (n-3 PUFA) muscle lipid composition was increased from W0 to W2 and continued to rise at W4. n-3 PUFA blood lipid composition was increased from W0 to W1 and remained elevated for the remaining time points. Total protein content of focal adhesion kinase (FAK) increased from W0 to W4 whereas total mechanistic target of rapamycin (mTOR) was increased from W0 at W1 with no further significant increases at W2 and W4. These data show that FO supplementation results in discordant changes in the n-3 PUFA composition of skeletal muscle compared to blood that is associated with increases in total FAK content., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Multiracial individuals often do not easily fit into existing racial categories. Perceivers may adopt a novel racial category to categorize multiracial targets, but their willingness to do so may depend on their motivations. We investigated whether perceivers' levels of internal motivation to control prejudice (IMS) and external motivation to control prejudice (EMS) predicted their likelihood of categorizing Black-White multiracial faces as Multiracial. Across four studies, IMS positively predicted perceivers' categorizations of multiracial faces as Multiracial. The association between IMS and Multiracial categorizations was strongest when faces were most racially ambiguous. Explicit prejudice, implicit prejudice, and interracial contact were ruled out as explanations for the relationship between IMS and Multiracial categorizations. EMS may be negatively associated with the use of the Multiracial category. Therefore, perceivers' motivations to control prejudice have important implications for racial categorization processes.

AMPK (AMP-dependant protein kinase)-mTORC1 (mechanistic target of rapamycin in complex 1)-p70S6K1 (ribosomal protein S6 kinase 1 of 70 kDa) signaling plays a crucial role in muscle protein synthesis (MPS). Understanding this pathway has been advanced by the application of the Western blot (WB) technique. However, because many components of the mTORC1 pathway undergo numerous, multisite posttranslational modifications, solely studying the phosphorylation changes of mTORC1 and its substrates may not adequately represent the true metabolic signaling processes. The aim of this study was to develop and apply a quantitative in vitro [γ-(32)P] ATP kinase assay (KA) for p70S6K1 to assess kinase activity in human skeletal muscle to resistance exercise (RE) and protein feeding. In an initial series of experiments the assay was validated in tissue culture and in p70S6K1-knockout tissues. Following these experiments, the methodology was applied to assess p70S6K1 signaling responses to a physiologically relevant stimulus. Six men performed unilateral RE followed by the consumption of 20 g of protein. Muscle biopsies were obtained at pre-RE, and 1 and 3 h post-RE. In response to RE and protein consumption, p70S6K1 activity as assessed by the KA was significantly increased from pre-RE at 1 and 3 h post-RE. However, phosphorylated p70S6K1(thr389) was not significantly elevated. AMPK activity was suppressed from pre-RE at 3 h post-RE, whereas phosphorylated ACC(ser79) was unchanged. Total protein kinase B activity also was unchanged after RE from pre-RE levels. Of the other markers we assessed by WB, 4EBP1(thr37/46) phosphorylation was the only significant responder, being elevated at 3 h post-RE from pre-RE. These data highlight the utility of the KA to study skeletal muscle plasticity.

Knockout of Kv1.3 improves glucose homeostasis and confers resistance to obesity. Additionally, Kv1.3 inhibition enhances glucose uptake. This is thought to occur through calcium release. Kv1.3 inhibition in T-lymphocytes alters mitochondrial membrane potential, and, as many agents that induce Ca(2+) release or inhibit mitochondrial function activate AMPK, we hypothesised that Kv1.3 inhibition would activate AMPK and increase glucose uptake. We screened cultured muscle with a range of Kv1.3 inhibitors for their ability to alter glucose uptake. Only Psora4 increased glucose uptake in C2C12 myotubes. None of the inhibitors had any impact on L6 myotubes. Magratoxin activated AMPK in C2C12 myotubes and only Pap1 activated AMPK in the SOL. Kv1.3 inhibitors did not alter cellular respiration, indicating a lack of effect on mitochondrial function. In conclusion, AMPK does not mediate the effects of Kv1.3 inhibitors and they display differential effects in different skeletal muscle cell lines without impairing mitochondrial function.

A mouse model of cystitis caused by uropathogenic Escherichia coli was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic E. coli infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic E. coli.

Lawsonia intracellularis infection causes proliferative enteropathy (PE) in many mammalian species, with porcine and equine proliferative enteropathy (PPE and EPE) known worldwide. Hamsters are a well-published animal model for PPE infection studies in pigs. There is no laboratory animal model for EPE infection studies and it is not known whether there is species-specificity for equine or porcine isolates of L. intracellularis in animal models. The objective of this study was to determine whether it is possible to generate typical EPE lesions in hamsters after inoculation with an equine strain of L. intracellularis (EPE strain) and whether it is comparatively possible to generate PPE lesions in rabbits after inoculation with a porcine strain of L. intracellularis (PPE strain). In 2 separate trials, 4-week-old and 3-week-old weanling golden Syrian hamsters were challenged with EPE strains and compared to uninfected (both trials) and PPE-infected controls (Trial 2 only). Concurrently, 6 female New Zealand white juvenile rabbits were infected with PPE strain and observed concomitantly to 8 similar rabbits infected with EPE strain for a different experiment. Hamsters and rabbits were observed for 21 to 24 days post-infection (DPI), depending on the experiment. Neither infected species developed clinical signs. The presence of disease was assessed with diagnostic techniques classically used for pigs and horses: immune-peroxidase monolayer assay on sera; quantitative polymerase chain reaction (qPCR) detection of molecular DNA in feces; and hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) on intestinal tissues. Our results showed that EPE-challenged hamsters do not develop infection when compared with PPE controls (IHC, P = 0.009; qPCR, P = 0.0003). Conversely, PPE-challenged rabbits do not develop typical intestinal lesions in comparison to EPE-challenged rabbits, with serological response at 14 DPI being significantly lower (P = 0.0023). In conclusion, PPE and EPE strains appear to have different host-specificities for hamsters and rabbits, respectively.

Myostatin is a TGFβ family member and negative regulator of muscle size. Due to the complexity of the molecular pathway between myostatin mRNA/protein and changes in transcription, it has been difficult to understand whether myostatin plays a role in resistance exercise-induced skeletal muscle hypertrophy. To circumvent this problem, we determined the expression of a unique myostatin target gene, Mighty, following resistance exercise. Mighty mRNA increased by 6 h (82.9 ± 24.21%) and remained high out to 48 h (56.5 ± 19.67%) after resistance exercise. Further examination of the soleus, plantaris and tibialis anterior muscles showed that the change in Mighty mRNA at 6 h correlated with the increase in muscle size associated with this protocol (R(2) = 0.9996). The increase in Mighty mRNA occurred both independent of Smad2 phosphorylation and in spite of an increase in myostatin mRNA (341.8 ± 147.14% at 3 h). The myostatin inhibitor SKI remained unchanged. However, activated Notch, another potential inhibitor of TGFβ signaling, increased immediately following resistance exercise (83 ± 11.2%) and stayed elevated out to 6 h (78 ± 16.6%). Electroportion of the Notch intracellular domain into the tibialis anterior resulted in an increase in Mighty mRNA (63 ± 13.4%) that was equivalent to the canonical Notch target HES-1 (94.4 ± 7.32%). These data suggest that acute resistance exercise decreases myostatin signaling through the activation of the TGFβ inhibitor Notch resulting in a decrease in myostatin transcriptional activity that correlates well with muscle hypertrophy.

Aims/hypothesis: The NAD(+)-dependent protein deacetylase sirtuin (SIRT)1 is thought to be a key regulator of skeletal muscle metabolism. However, its precise role in the regulation of insulin sensitivity is unclear. Accordingly, we sought to determine the effect of skeletal muscle-specific overexpression of SIRT1 on skeletal muscle insulin sensitivity and whole-body energy metabolism., Methods: At 10 weeks of age, mice with muscle-specific overexpression of SIRT1 and their wild-type littermates were fed a standard diet with free access to chow or an energy-restricted (60% of standard) diet for 20 days. Energy expenditure and body composition were measured by indirect calorimetry and magnetic resonance imaging, respectively. Skeletal muscle insulin-stimulated glucose uptake was measured ex vivo in soleus and extensor digitorum longus muscles using a 2-deoxyglucose uptake technique with a physiological insulin concentration of 360 pmol/l (60 μU/ml)., Results: Sirt1 mRNA and SIRT1 protein levels were increased by approximately 100- and 150-fold, respectively, in skeletal muscle of mice with SIRT1 overexpression compared with wild-type mice. Despite this large-scale overexpression of SIRT1, body composition, whole-body energy expenditure, substrate oxidation and voluntary activity were comparable between genotypes. Similarly, skeletal muscle basal and insulin-stimulated glucose uptake were unaltered with SIRT1 overexpression. Finally, while 20 days of energy restriction enhanced insulin-stimulated glucose uptake in skeletal muscles of wild-type mice, no additional effect of SIRT1 overexpression was observed., Conclusions/interpretation: These results demonstrate that upregulation of SIRT1 activity in skeletal muscle does not affect whole-body energy expenditure or enhance skeletal muscle insulin sensitivity in young mice on a standard diet with free access to chow or in young mice on energy-restricted diets.

The objective of this study was to demonstrate the susceptibility of rabbits to Lawsonia intracellularis obtained from a case of clinical equine proliferative enteropathy (EPE). This is a preliminary step toward developing a rabbit infection model for studying pathogenesis and therapy of EPE in horses. Nine does were equally assigned to 3 groups. Animals in 2 groups (Group 1 and Group 2) were orally inoculated with different doses of cell-cultured L. intracellularis. Controls (Group 3) were sham-inoculated. Feces and blood were collected before the rabbits were infected and at 7, 14, and 21 days post-infection (DPI). Serum immunoglobulin G (IgG) titers were measured using an immunoperoxidase monolayer assay (IPMA) and fecal samples were analyzed with quantitative polymerase chain reaction (qPCR). A doe from each group was euthanized at 7, 14, and 21 DPI for collection and evaluation of intestinal samples. Tissues were stained by routine hematoxylin and eosin (H&E) method and immunohistochemistry (IHC) with L. intracellularis-specific mouse monoclonal antibody. At 14 DPI, serologic responses were detected in both infected groups, which maintained high titers through to 21 DPI. Lawsonia intracellularis DNA was detected in the feces of Group 2 on 7 DPI and in both infected groups on 14 DPI. Gross lesions were apparent in Group 1 and Group 2 on 14 DPI. Immunohistochemistry confirmed L. intracellularis antigen within cells of rabbits in Group 1 and Group 2 on 7, 14, and 21 DPI. No lesions, serologic response, shedding, or IHC labeling were found in Group 3 rabbits. This study describes an EPE rabbit model that simulates natural infection, as typical lesions, immune response, and fecal shedding were present.

This study was undertaken to investigate physiological adaptation with two endurance-training periods differing in intensity distribution. In a randomized crossover fashion, separated by 4 wk of detraining, 12 male cyclists completed two 6-wk training periods: 1) a polarized model [6.4 (±1.4 SD) h/wk; 80%, 0%, and 20% of training time in low-, moderate-, and high-intensity zones, respectively]; and 2) a threshold model [7.5 (±2.0 SD) h/wk; 57%, 43%, and 0% training-intensity distribution]. Before and after each training period, following 2 days of diet and exercise control, fasted skeletal muscle biopsies were obtained for mitochondrial enzyme activity and monocarboxylate transporter (MCT) 1 and 4 expression, and morning first-void urine samples were collected for NMR spectroscopy-based metabolomics analysis. Endurance performance (40-km time trial), incremental exercise, peak power output (PPO), and high-intensity exercise capacity (95% maximal work rate to exhaustion) were also assessed. Endurance performance, PPOs, lactate threshold (LT), MCT4, and high-intensity exercise capacity all increased over both training periods. Improvements were greater following polarized rather than threshold for PPO [mean (±SE) change of 8 (±2)% vs. 3 (±1)%, P < 0.05], LT [9 (±3)% vs. 2 (±4)%, P < 0.05], and high-intensity exercise capacity [85 (±14)% vs. 37 (±14)%, P < 0.05]. No changes in mitochondrial enzyme activities or MCT1 were observed following training. A significant multilevel, partial least squares-discriminant analysis model was obtained for the threshold model but not the polarized model in the metabolomics analysis. A polarized training distribution results in greater systemic adaptation over 6 wk in already well-trained cyclists. Markers of muscle metabolic adaptation are largely unchanged, but metabolomics markers suggest different cellular metabolic stress that requires further investigation.

Activation of mammalian target of rapamycin 1 (mTORC1) by nutrients, insulin and leptin leads to appetite suppression (anorexia). Contrastingly, increased AMP-activated protein kinase (AMPK) activity by ghrelin promotes appetite (orexia). However, the interplay between these mechanisms remains poorly defined. The relationship between the anorexigenic hormones, insulin and leptin, and the orexigenic hormone, ghrelin, on mTORC1 signalling was examined using S6 kinase phosphorylation as a marker for changes in mTORC1 activity in mouse hypothalamic GT1-7 cells. Additionally, the contribution of AMPK and mTORC1 signalling in relation to insulin-, leptin- and ghrelin-driven alterations to mouse hypothalamic agouti-related protein (AgRP) mRNA levels was examined. Insulin and leptin increase mTORC1 activity in a phosphoinositide-3-kinase (PI3K)- and protein kinase B (PKB)-dependent manner, compared to vehicle controls, whereas increasing AMPK activity inhibits mTORC1 activity and blocks the actions of the anorexigenic hormones. Ghrelin mediates an AMPK-dependent decrease in mTORC1 activity and increases hypothalamic AgRP mRNA levels, the latter effect being prevented by insulin in an mTORC1-dependent manner. In conclusion, mTORC1 acts as an integration node in hypothalamic neurons for hormone-derived PI3K and AMPK signalling and mediates at least part of the assimilated output of anorexigenic and orexigenic hormone actions in the hypothalamus., (Copyright © 2012 S. Karger AG, Basel.)

Aims/hypothesis: Hypothalamic glucose-excited (GE) neurons contribute to whole-body glucose homeostasis and participate in the detection of hypoglycaemia. This system appears defective in type 1 diabetes, in which hypoglycaemia commonly occurs. Unfortunately, it is at present unclear which molecular components required for glucose sensing are produced in individual neurons and how these are functionally linked. We used the GT1-7 mouse hypothalamic cell line to address these issues., Methods: Electrophysiological recordings, coupled with measurements of gene expression and protein levels and activity, were made from unmodified GT1-7 cells and cells in which AMP-activated protein kinase (AMPK) catalytic subunit gene expression and activity were reduced., Results: Hypothalamic GT1-7 neurons express the genes encoding glucokinase and ATP-sensitive K(+) channel (K(ATP)) subunits K ( ir ) 6.2 and Sur1 and exhibit GE-type glucose-sensing behaviour. Lowered extracellular glucose concentration hyperpolarised the cells in a concentration-dependent manner, an outcome that was reversed by tolbutamide. Inhibition of glucose uptake or metabolism hyperpolarised cells, showing that energy metabolism is required to maintain their resting membrane potential. Short hairpin (sh)RNA directed to Ampkα2 (also known as Prkaa2) reduced GT1-7 cell AMPKα2, but not AMPKα1, activity and lowered the threshold for hypoglycaemia-induced hyperpolarisation. shAmpkα1 (also known as Prkaa1) had no effect on glucose-sensing or AMPKα2 activity. Decreased uncoupling protein 2 (Ucp2) mRNA was detected in AMPKα2-reduced cells, suggesting that AMPKα2 regulates UCP2 levels., Conclusions/interpretation: We have demonstrated that GT1-7 cells closely mimic GE neuron glucose-sensing behaviour, and reducing AMPKα2 blunts their responsiveness to hypoglycaemic challenge, possibly by altering UCP2 activity. These results show that suppression of AMPKα2 activity inhibits normal glucose-sensing behaviour and may contribute to defective detection of hypoglycaemia.

In recent decades, the antihyperglycemic biguanide metformin has been used extensively in the treatment of type 2 diabetes, despite continuing uncertainty over its direct target. In this article, using two independent approaches, we demonstrate that cellular actions of metformin are disrupted by interference with its metal-binding properties, which have been known for over a century but little studied by biologists. We demonstrate that copper sequestration opposes known actions of metformin not only on AMP-activated protein kinase (AMPK)-dependent signaling, but also on S6 protein phosphorylation. Biguanide/metal interactions are stabilized by extensive π-electron delocalization and by investigating analogs of metformin; we provide evidence that this intrinsic property enables biguanides to regulate AMPK, glucose production, gluconeogenic gene expression, mitochondrial respiration, and mitochondrial copper binding. In contrast, regulation of S6 phosphorylation is prevented only by direct modification of the metal-liganding groups of the biguanide structure, supporting recent data that AMPK and S6 phosphorylation are regulated independently by biguanides. Additional studies with pioglitazone suggest that mitochondrial copper is targeted by both of these clinically important drugs. Together, these results suggest that cellular effects of biguanides depend on their metal-binding properties. This link may illuminate a better understanding of the molecular mechanisms enabling antihyperglycemic drug action.

Researchers may place a catheter in the ear vessel of a rabbit for a short period of time in order to collect repeated blood samples without extensive restraint of the animal. Maintaining such a catheter in a healthy rabbit can be challenging, as the animal may scratch at the ear, removing the catheter or forming a large hematoma that might impede blood sampling. The authors developed a technique for protecting the indwelling catheter by cutting a section of moleskin to the same shape as the ear and gluing it to the surface of the ear and the catheter. They applied this technique to collect multiple blood samples during 12-h periods from nine rabbits in a pharmacokinetics study. Catheters remained patent in five rabbits for 12 h, in two rabbits for 8 h, in one rabbit for 6 h and in one rabbit for 4 h. This technique allowed for collection of repeated blood samples and prevented the rabbits from interfering with the catheter while allowing them to move freely during the sampling period.

In a crossover study, 5 calves were made acidotic by intermittent intravenous infusion of isotonic hydrochloric acid (HCl) over approximately 24 h. This was followed by rapid (4 h) or slow (24 h) correction of blood pH with isotonic sodium bicarbonate (NaHCO(3)) to determine if rapid correction of acidemia produced paradoxical cerebrospinal fluid (CSF) acidosis. Infusion of HCl produced a marked metabolic acidosis with respiratory compensation. Venous blood pH (mean ± S(x)) was 7.362 ± 0.021 and 7.116 ± 0.032, partial pressure of carbon dioxide (Pco(2), torr) 48.8 ± 1.3 and 34.8 ± 1.4, and bicarbonate (mmol/L), 27.2 ± 1.27 and 11 ± 0.96; CSF pH was 7.344 ± 0.031 and 7.240 ± 0.039, Pco(2) 42.8 ± 2.9 and 34.5 ± 1.4, and bicarbonate 23.5 ± 0.91 and 14.2 ± 1.09 for the period before the infusion of hydrochloric acid and immediately before the start of sodium bicarbonate correction, respectively. In calves treated with rapid infusion of sodium bicarbonate, correction of venous acidemia was significantly more rapid and increases in Pco(2) and bicarbonate in CSF were also more rapid. However, there was no significant difference in CSF pH. After 4 h of correction, CSF pH was 7.238 ± 0.040 and 7.256 ± 0.050, Pco(2) 44.4 ± 2.2 and 34.2 ± 2.1, and bicarbonate 17.8 ± 1.02 and 14.6 ± 1.4 for rapid and slow correction, respectively. Under the conditions of this experiment, rapid correction of acidemia did not provoke paradoxical CSF acidosis.

The effects of part-list cueing and of collaborative recall in memory performance have been recently addressed as parallel phenomena. Notably they both impair recall (and boost frequency estimates) and they have been explained by the same underlying mechanisms. However, the comparability between the two paradigms is hindered by a number of procedural differences. The main contribution of this paper is the introduction of a new paradigm that makes standard part-list cueing and collaborative recall more comparable. In our study we compared free recall and frequency estimates of participants in a non-cueing condition with the same performance in a standard part-list cueing condition and in a condition in which part-list cues were gradually presented during recall (as it occurs in collaborative recall). Results indicate that the effects of part-list cueing continued to be reliable in both cueing conditions. Namely, recall was impaired and frequency estimates were boosted relatively to a non-cueing condition. The results obtained with this new method that enhances the direct comparability of the two paradigms provide further evidence for the parallel between the two effects.

Insulin resistance and impaired glucose homoeostasis are important indicators of Type 2 diabetes and are early risk factors of AD (Alzheimer's disease). An essential feature of AD pathology is the presence of BACE1 (β-site amyloid precursor protein-cleaving enzyme 1), which regulates production of toxic amyloid peptides. However, whether BACE1 also plays a role in glucose homoeostasis is presently unknown. We have used transgenic mice to analyse the effects of loss of BACE1 on body weight, and lipid and glucose homoeostasis. BACE1-/- mice are lean, with decreased adiposity, higher energy expenditure, and improved glucose disposal and peripheral insulin sensitivity than wild-type littermates. BACE1-/- mice are also protected from diet-induced obesity. BACE1-deficient skeletal muscle and liver exhibit improved insulin sensitivity. In a skeletal muscle cell line, BACE1 inhibition increased glucose uptake and enhanced insulin sensitivity. The loss of BACE1 is associated with increased levels of UCP1 (uncoupling protein 1) in BAT (brown adipose tissue) and UCP2 and UCP3 mRNA in skeletal muscle, indicative of increased uncoupled respiration and metabolic inefficiency. Thus BACE1 levels may play a critical role in glucose and lipid homoeostasis in conditions of chronic nutrient excess. Therefore strategies that ameliorate BACE1 activity may be important novel approaches for the treatment of diabetes.

For over 10 years, we have known that the activation of the mammalian target of rapamycin complex 1 (mTORC1) has correlated with the increase in skeletal muscle size and strength that occurs following resistance exercise. Initial cell culture and rodent models of muscle growth demonstrated that the activation of mTORC1 is common to hypertrophy induced by growth factors and increased loading. The further observation that high loads increased the local production of growth factors led to the paradigm that resistance exercise stimulates the autocrine production of factors that act on membrane receptors to activate mTORC1, and this results in skeletal muscle hypertrophy. Over the last few years, there has been a paradigm shift. From both human and rodent studies, it has become clear that the phenotypic and molecular responses to resistance exercise occur in a growth factor-independent manner. Although the mechanism of load-induced mTORC1 activation remains to be determined, it is clear that it does not require classical growth factor signaling.

Sodium pyruvate can increase mitochondrial biogenesis in C2C12 myoblasts in a peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC1alpha)-independent manner. The present study examined the effect of 72-h treatment with sodium pyruvate (5-50 mM) or sodium chloride (50 mM) as an osmotic control on the regulation of mitochondrial substrate metabolism and biogenesis in C2C12 myotubes. Pyruvate (50 mM) increased the levels of fatty acid oxidation enzymes (CD36, 61%, and beta-oxidative enzyme 3-hydroxyacyl-CoA dehydrogenase, 54%) and the expression of cytochrome-c oxidase subunit I (220%) and cytochrome c (228%), consistent with its previous described role as a promoter of mitochondrial biogenesis. However, in contrast, pyruvate treatment reduced glucose transporter 4 (42%), phosphofructokinase (57%), and PGC1alpha (72%) protein content as well as PGC1alpha (48%) and PGC1beta (122%) mRNA. The decrease in PGC1alpha was compensated for by an increase in the PGC1alpha-related coactivator (PRC; 187%). Pyruvate treatment reduced basal and insulin-stimulated glucose uptake (41% and 31%, respectively) and palmitate uptake and oxidation (24% and 31%, respectively). The addition of the pyruvate dehydrogenase activator dichloroacetate (DCA) and the TCA precursor glutamine increased PGC1alpha expression (368%) and returned PRC expression to basal. Glucose uptake increased by 4.2-fold with DCA and glutamine and palmitate uptake increased by 18%. Coupled to this adaptation was an 80% increase in oxygen consumption. The data suggest that supraphysiological doses of pyruvate decrease mitochondrial function despite limited biogenesis and that anaplerotic agents can reverse this effect.

Background: Since activation of the PI3K/(protein kinase B; PKB/akt) pathway has been shown to alter muscle mass and growth, the aim of this study was to determine whether resistance exercise increased insulin like growth factor (IGF) I/phosphoinositide 3-kinase (PI3K) signalling and whether altering PI(3,4,5)P(3) metabolism genetically would increase load induced muscle growth., Methodology/principal Findings: Acute and chronic resistance exercise in wild type and muscle specific PTEN knockout mice were used to address the role of PI(3,4,5)P(3) regulation in the development of skeletal muscle hypertrophy. Acute resistance exercise did not increase either IGF-1 receptor phosphorylation or IRS1/2 associated p85. Since insulin/IGF signalling to PI3K was unchanged, we next sought to determine whether inactivation of PTEN played a role in load-induced muscle growth. Muscle specific knockout of PTEN resulted in small but significant increases in heart (PTEN(+/+) = 5.00+/-0.02 mg/g, PTEN(-/-) = 5.50+/-0.09 mg/g), and TA (PTEN(+/+) = 1.74+/-0.04 mg/g, PTEN(-/-) = 1.89 +/-0.03) muscle mass, while the GTN, SOL, EDL and PLN remain unchanged. Following ablation, hypertrophy of the PLN, SOL or EDL muscles was similar between PTEN(-/-) and PTEN(+/+) animals. Even though there were some changes in overload-induced PKB and S6K1 phosphorylation, 1 hr following acute resistance exercise there was no difference in the phosphorylation state of S6K1 Thr389 between genotypes., Conclusions/significance: These data suggest that physiological loading does not lead to the enhanced activation of the PI3K/PKB/mTORC1 axis and that neither PI3K activation nor PTEN, and by extension PI(3,4,5)P(3) levels, play a significant role in adult skeletal muscle growth.

Background: Myogenesis in C2C12 cells requires the activation of the PI3K/mTOR signaling pathways. Since mTOR signaling can feedback through S6K1 to inhibit the activation of PI3K, the aim of this work was to assess whether feedback from S6K1 played a role in myogenesis and determine whether siRNA mediated knockdown of S6K1 would lead to an increased rate of myotube formation., Results: S6K1 activity increased in a linear fashion following plating and was more than 3-fold higher after Day 3 of differentiation (subconfluent = 11.09 +/- 3.05, Day 3 = 29.34 +/- 3.58). IRS-1 levels tended to increase upon serum withdrawal but decreased approximately 2-fold (subconfluent = 0.88 +/- 0.10, Day 3 = 0.42 +/- 0.06) 3 days following differentiation whereas IRS-2 protein remained stable. IRS-1 associated p85 was significantly reduced upon serum withdrawal (subconfluent = 0.86 +/- 0.07, Day 0 = 0.31 +/- 0.05), remaining low through day 1. IRS-2 associated p85 decreased following serum withdrawal (subconfluent = 0.96 +/- 0.05, Day 1 = 0.56 +/- 0.08) and remained suppressed up to Day 3 following differentiation (0.56 +/- 0.05). Phospho-tyrosine associated p85 increased significantly from subconfluent to Day 0 and remained elevated throughout differentiation. siRNA directed against S6K1 and S6K2 did not result in changes in IRS-1 levels after either 48 or 96 hrs. Furthermore, neither 48 nor 96 hrs of S6K1 knockdown caused a change in myotube formation., Conclusions: Even though S6K1 activity increases throughout muscle cell differentiation and IRS-1 levels decrease over this period, siRNA suggests that S6K1 is not mediating the decrease in IRS-1. The decrease in IRS-1/2 associated p85 together with the increase in phospho-tyrosine associated p85 suggests that PI3K associates primarily with scaffolds other than IRS-1/2 during muscle cell differentiation.

Following resistance exercise in the fasted state, both protein synthesis and degradation in skeletal muscle are increased. The addition of essential amino acids potentiates the synthetic response suggesting that an amino acid sensor, which is involved in both synthesis and degradation, may be activated by resistance exercise. One such candidate protein is the class 3 phosphatidylinositol 3OH-kinase (PI3K) Vps34. To determine whether mammalian Vps34 (mVps34) is modulated by high-resistance contractions, mVps34 and S6K1 (an index of mTORC1) activity were measured in the distal hindlimb muscles of rats 0.5, 3, 6 and 18 h after acute unilateral high-resistance contractions with the contralateral muscles serving as a control. In the lengthening tibialis anterior (TA) muscle, S6K1 (0.5 h = 366.3 +/- 112.08%, 3 h = 124.7 +/- 15.96% and 6 h = 129.2 +/- 0%) and mVps34 (3 h = 68.8 +/- 15.1% and 6 h = 36.0 +/- 8.79%) activity both increased, whereas in the shortening soleus and plantaris (PLN) muscles the increase was significantly lower (PLN S6K1 0.5 h = 33.1 +/- 2.29% and 3 h = 47.0 +/- 6.65%; mVps34 3 h = 24.5 +/- 7.92%). HPLC analysis of the TA demonstrated a 25% increase in intramuscular leucine concentration in rats 1.5 h after exercise. A similar level of leucine added to C2C12 cells in vitro increased mVps34 activity 3.2-fold. These data suggest that, following high-resistance contractions, mVps34 activity is stimulated by an influx of essential amino acids such as leucine and this may prolong mTORC1 signalling and contribute to muscle hypertrophy.

Resistance-exercise training results in a progressive increase in muscle mass and force production. Following an acute bout of resistance exercise, the rate of protein synthesis increases proportionally with the increase in protein degradation, correlating at 3 h in the starved state. Amino acids taken immediately before or immediately after exercise increase the post-exercise rate of protein synthesis. Therefore a protein that controls protein degradation and amino acid-sensitivity would be a potential candidate for controlling the activation of protein synthesis following resistance exercise. One such candidate is the class III PI3K (phosphoinositide 3-kinase) Vps34 (vacuolar protein sorting mutant 34). Vps34 controls both autophagy and amino acid signalling to mTOR (mammalian target of rapamycin) and its downstream target p70 S6K1 (S6 kinase 1). We have identified a significant increase in mVps34 (mammalian Vps34) activity 3 h after resistance exercise, continuing for at least 6 h, and propose a mechanism whereby mVps34 could act as an internal amino acid sensor to mTOR after resistance exercise.

In 3 studies, the authors tested the hypothesis that Chinese participants would view social groups as more entitative than would Americans and, as a result, would be more likely to infer personality traits on the basis of group membership--that is, to stereotype. In Study 1, Chinese participants made stronger stereotypic trait inferences than Americans did on the basis of a target's membership in a fictitious group. Studies 2 and 3 showed that Chinese participants perceived diverse groups as more entitative and attributed more internally consistent dispositions to groups and their members. Guided by culturally based lay theories about the entitative nature of groups, Chinese participants may stereotype more readily than do Americans when group membership is available as a source of dispositional inference., ((PsycINFO Database Record (c) 2007 APA, all rights reserved).)

Attainment of a brown adipocyte cell phenotype in white adipocytes, with their abundant mitochondria and increased energy expenditure potential, is a legitimate strategy for combating obesity. The unique transcriptional regulators of the primary brown adipocyte phenotype are unknown, limiting our ability to promote brown adipogenesis over white. In the present work, we used microarray analysis strategies to study primary preadipocytes, and we made the striking discovery that brown preadipocytes demonstrate a myogenic transcriptional signature, whereas both brown and white primary preadipocytes demonstrate signatures distinct from those found in immortalized adipogenic models. We found a plausible SIRT1-related transcriptional signature during brown adipocyte differentiation that may contribute to silencing the myogenic signature. In contrast to brown preadipocytes or skeletal muscle cells, white preadipocytes express Tcf21, a transcription factor that has been shown to suppress myogenesis and nuclear receptor activity. In addition, we identified a number of developmental genes that are differentially expressed between brown and white preadipocytes and that have recently been implicated in human obesity. The interlinkage between the myocyte and the brown preadipocyte confirms the distinct origin for brown versus white adipose tissue and also represents a plausible explanation as to why brown adipocytes ultimately specialize in lipid catabolism rather than storage, much like oxidative skeletal muscle tissue.

Research indicates that people's intuitive beliefs about groups are organized according to a group typology (B. Lickel, D. L. Hamilton, & S. J. Sherman, 2001). In Study 1, the authors compared and contrasted people's spontaneous cognitive representations of two group types, task groups and social categories. Analyses revealed significant differences as well as commonalities in people's beliefs about the group types. Notably, perceivers used more abstract, enduring language and contextually rich descriptors when characterizing social categories than when describing task groups. In Study 2, the authors investigated the differential roles of distinct group perception variables (entitativity, homogeneity, essence, role differentiation, and agency) as predictors of stereotyping for the different group types. Entitativity and all of the group perception variables significantly predicted stereotyping for both social categories and task groups. However, perceptions of entitativity mediated the association between the group perception variables and stereotypic judgments. These findings demonstrate that laypeople hold stereotype-like mental representations of group types other than social categories and that entitativity plays a crucial mediating role in stereotyping across different types of groups., (2007 APA, all rights reserved)

The effect of changes in feed intake on auscultatable gastrointestinal sounds has not been systematically studied. Disagreement also is present in the literature about variation in sounds according to the quadrant of auscultation. Gastrointestinal sounds were recorded over the center of the left dorsal, left ventral, right ventral, and right dorsal quadrants and over the middle of the right abdominal flank. During 24 hours (n = 4) or 48 hours (n = 5) of fasting, there was a reduction in the intensity of gastrointestinal sounds as assessed by analysis of sound recordings. There was also a reduction in the number of mixing-like and propulsive-like sounds heard by 2 blinded observers. After refeeding, there was a marked increase in sound. Sound intensity varied among abdominal quadrants, but blinded observers did not notice significant differences in the number of mixing-like sounds. The left dorsal quadrant was quieter than others during fasting and refeeding. The right ventral quadrant appeared to be least affected by fasting, and sounds were louder over the right ventral and right middle quadrants than over the others. The blinded observers' perceptions of sound correlated poorly with one another and with objective measures of sound intensity. This experiment demonstrates the effectiveness of computerized analysis of abdominal sound in detecting a reduction in the intensity of gastrointestinal sounds during fasting and their return during refeeding. The left dorsal quadrant was quieter than other quadrants, likely because of its position over the small colon. There was considerable observer variation in the number of intestinal sounds heard.

Purpose: To determine if a pterygium surgical procedure consisting of minimal conjunctival removal, excision of the hypertrophic subconjunctival fibrovascular tissue, application of mitomycin 0.25 mg/mL for 1 minute combined with temporary nasal tarsorrhaphy, and use of postoperative dexamethasone/antibiotic drops achieves the following: safely simplifies pterygium removal, controls the early side effects of mitomycin, reduces the rate of recurrence, and lessens the need for conjunctival transplantation., Methods: Twenty eyes in 19 patients underwent the procedure with use of mitomycin; 15 eyes had primary and 5 had recurrent pterygia. These were compared with a previous group of 28 eyes in 26 patients that underwent pterygium/tarsorrhaphy surgery without use of mitomycin; 20 eyes had primary and 8 had recurrent pterygia. Postoperatively, all eyes in both groups were treated with dexamethasone/antibiotic drops., Results: In the mitomycin group, with an average follow-up of 12.1 months, 19 eyes healed uneventfully; there have been no recurrences. The nonmitomycin group, with an average follow-up of 42.6 months, has had nine recurrences (32%); four required a second procedure. Recurrence was significantly lower in the mitomycin group (P = .006). Conjunctival healing, as reflected in the time from surgery until tarsorrhaphy opening, was significantly delayed in the mitomycin group, 36.7 versus 17 days (P = .001). The delay in conjunctival healing may explain the complications associated with the use of mitomycin in pterygium surgery., Conclusion: Minimal conjunctival removal, extensive fibrovascular tissue excision, 1-minute application of mitomycin 0.25 mg/mL, temporary nasal tarsorrhaphy, and frequent application of dexamethasone/antibiotic drops postoperatively provided a safe and successful approach to pterygium management in this series.

Problems in ion and fluid transfer across the retinal pigment epithelium (RPE) are a probable cause of inappropriate accumulations of fluid between the photoreceptors of the retina and the RPE. The activities of Cl- transporters involved in basal fluid transfer across the RPE have been compared to determine whether Ca2+- or cAMP-dependent channels may be responsible for basal housekeeping levels of secretory activity in this tissue. The role of a candidate Ca2+-dependent CLCA protein in the basal RPE transport of Cl- has been investigated. Low concentrations of the Cl- conductance inhibitors glibenclamide and 5-nitro-2-(3-phenylpropylamino)benzoate reduced the short-circuit current in dog RPE preparations mounted in Ussing chambers and decreased the Ca2+-dependent Cl- efflux from fibroblasts expressing the pCLCA1 Cl- conductance regulator. However, these same agents did not inhibit the rate of Cl- release from cultured fibroblasts expressing the cystic fibrosis transmembrane regulator (CFTR) conductive Cl- channel. Addition of ionomycin to primary cultures of canine RPE cells or to fibroblasts expressing the pCLCA1 channel regulator increased the rate of release of Cl- from both types of cultured cells. However, the presence of pCLCA1 also increased cAMP-dependent Cl- release from fibroblasts expressing CFTR. We conclude that Ca2+-dependent Cl- transport may be more important than cAMP-dependent Cl- transport for normal fluid secretion across the RPE. Furthermore, CLCA proteins expressed in the RPE appear to regulate the activity of other Cl- transporters, rather than functioning as primary ion transport proteins.