The effects of 12 weeks of walking with and without blood flow reduction on bone turnover markers in college-aged women

Walking while reducing blood flow to and from the working muscles has been shown to result in strength gains and increased muscle cross-sectional area (MCSA) in young men and older adults. However, little is known about the effects of this type of novel exercise on bone metabolism and bone health. PURPOSE: To determine the effects of 12 weeks of low-intensity treadmill walking with and without blood flow restriction (BFR) on serum markers of bone metabolism in college-aged women. Secondary objectives were to examine changes in thigh and calf MCSA, muscle strength, aerobic capacity, and bone characteristics of the tibia following the intervention. METHODS: Thirty-one young women, aged 18 to 30 years, were randomly assigned to one of three groups: low-intensity treadmill walking control (WALK) (n=10), low-intensity treadmill walking with blood flow restriction (BFR) (n-11), or a non-exercise control group (CON) (n=10). Subjects in the BFR and WALK groups walked on a treadmill at a speed associated with 45% VO2peak for up to 20 minutes four days per week for 12 weeks. The BFR group wore 5 cm wide electronically monitored elastic pressure cuffs around their upper thighs during walk training. BFR cuffs were inflated to an initial pressure of 140 mmHg for the first four weeks, and then increased by 20 mmHg at week five (160 mmHg) and again at the start of week nine (180 mmHg). The CON group was asked not to change their normal physical activity levels or dietary habits over the duration of the training period. Baseline and post-testing measurements included blood sampling for the assessment of bone-specific alkaline phosphatase (Bone ALP) and tartrate-resistant acid phosphatase isoform 5b (TRAP5b); one repetition maximum (1RM) and maximal voluntary contraction (MVC) strength testing for knee extension and flexion; graded treadmill exercise test (GXT) for the determination of VO2peak; dual energy x-ray absorptiometry (DXA) to measure areal bone mineral density (aBMD) and body compsition; and peripheral Quantitative Computed Tomography (pQCT) to measure volumetric bone mineral density (vBMD) and bone area of the tibia as well as MCSA of the thigh and calf. RESULTS: A significant group x time interaction occurred for Bone ALP (p=0.02), as serum concentrations of Bone ALP were reduced in both BFR (-5.8%) and CON (-9.7%) groups post-training. Serum levels of TRAP5b and the ratio of Bone ALP to TRAP5b did not significantly change post-training. A significant group x time interaction was found for body weight (p=0.034). However, follow up analyses failed to find post-training group differences or within group changes over time (p>0.05). After analyzing percent change in body weight from baseline, significant group differences were observed between BFR (-0.8%) and WALK (2.4%) groups (p=0.046). A significant time effect (p=0.02) and group x time interaction (p=0.002) was observed for MCSA at the tibia 66% site. Follow up analyses revealed that MCSA significantly increased from baseline in both BFR (1.8%) and WALK (3.6%) groups (p<0.05). Significant time effects were found for MVC knee extension strength at joint angles of 30 degrees (p=0.02) and 60 degrees (p=0.004), with no differences between groups. A significant group x time interaction occurred for 1RM knee extension strength (p=0.014), with follow up analysis revealing a significant (p=0.026) increase in strength in the BFR group (4.5%) post-training. Significant main effects for time were found for trabecular bone content (p=0.036) and trabecular vBMD (p=0.024) at the tibia 4% site, both of which decreased over the study duration. Significant time effects were also found for total bone content (p=0.036) and SSI (p=0.011) at the tibia 38% site as well as total bone content (p=0.043), total vBMD (p=0.029), total bone area (p=0.001), periosteal circumference (p=0.002), and endosteal circumference at the 66% site. Total vBMD at the 66% site decreased post-training, whereas the other variables with significant time effects increased over the study duration. CONCLUSION: Twelve weeks of walking with BFR resulted in reduced levels of bone formation with no change in bone resorption in young women. Additionally, BFR walking resulted in favorable neuromuscular changes

Bovine Milk Extracellular Vesicles (EVs) Modification Elicits Skeletal Muscle Growth in Rats

The current study investigated how bovine milk extracellular vesicles (EVs) affected rotarod performance and biomarkers of skeletal muscle physiology in young, growing rats. Twenty-eight-day Fisher 344 rats were provided an AIN-93G-based diet for 4 weeks that either remained unadulterated [EVs and RNA-sufficient (ERS; n = 12)] or was sonicated [EVs and RNA-depleted (ERD; n = 12)]. Prior to (PRE) and on the last day of the intervention (POST), animals were tested for maximal rotarod performance. Following the feeding period, the gastrocnemius muscle was analyzed at the histological, biochemical, and molecular levels and was also used to measure mitochondrial function and reactive oxygen species (ROS) emission. A main effect of time was observed for rotarod time (PRE \u3e POST, p = 0.001). Terminal gastrocnemius mass was unaffected by diet, although gastrocnemius muscle fiber cross sectional area was 11% greater (p = 0.018) and total RNA (a surrogate of ribosome density) was 24% greater (p = 0.001) in ERD. Transcriptomic analysis of the gastrocnemius indicated that 22 mRNAs were significantly greater in ERS versus ERD (p \u3c 0.01), whereas 55 mRNAs were greater in ERD versus ERS (p \u3c 0.01). There were no differences in gastrocnemius citrate synthase activity or mitochondrial coupling (respiratory control ratio), although mitochondrial ROS production was lower in ERD gastrocnemius (p = 0.016), which may be explained by an increase in glutathione peroxidase protein levels (p = 0.020) in ERD gastrocnemius. Dietary EVs profiling confirmed that sonication in the ERD diet reduced EVs content by ∼60%. Our findings demonstrate that bovine milk EVs depletion through sonication elicits anabolic and transcriptomic effects in the gastrocnemius muscle of rapidly maturing rats. While this did not translate into a functional outcome between diets (i.e., rotarod performance), longer feeding periods may be needed to observe such functional effects

Pre-training Skeletal Muscle Fiber Size and Predominant Fiber Type Best Predict Hypertrophic Responses to 6 Weeks of Resistance Training in Previously Trained Young Men

Limited evidence exists regarding differentially expressed biomarkers between previously-trained low versus high hypertrophic responders in response to resistance training. Herein, 30 college-aged males (training age 5 ± 3 years; mean ± SD) partook in 6 weeks of high-volume resistance training. Body composition, right leg vastus lateralis (VL) biopsies, and blood were obtained prior to training (PRE) and at the 3-week (W3) and 6-week time points (W6). The 10 lowest (LOW) and 10 highest (HIGH) hypertrophic responders were clustered based upon a composite hypertrophy score of PRE-to-W6 changes in right leg VL mean muscle fiber cross-sectional area (fCSA), VL thickness assessed via ultrasound, upper right leg lean soft tissue mass assessed via dual x-ray absorptiometry (DXA), and mid-thigh circumference. Two-way ANOVAs were used to compare biomarker differences between the LOW and HIGH clusters over time, and stepwise linear regression was performed to elucidate biomarkers that explained significant variation in the composite hypertrophy score from PRE to W3, W3 to W6, and PRE to W6 in all 30 participants. PRE-to-W6 HIGH and LOW responders exhibited a composite hypertrophy change of +10.7 ± 3.2 and -2.1 ± 1.6%, respectively (p &lt; 0.001). Compared to HIGH responders, LOW responders exhibited greater PRE type II fCSA (+18%, p = 0.022). Time effects (p &lt; 0.05) existed for total RNA/mg muscle (W6 &gt; W3 &gt; PRE), phospho (p)-4EBP1 (PRE &gt; W3&amp;W6), pan-mTOR (PRE &gt; W3 &lt; W6), p-mTOR (PRE &gt; W3 &lt; W6), pan-AMPKα (PRE &gt; W3 &lt; W6), pan-p70s6k (PRE &gt; W3), muscle ubiquitin-labeled proteins (PRE &gt; W6), mechano growth factor mRNA (W6 &gt; W3&amp;PRE), 45S rRNA (PRE &gt; W6), and muscle citrate synthase activity (PRE &gt; W3&amp;W6). No interactions existed for the aforementioned biomarkers and/or other assayed targets (muscle 20S proteasome activity, serum total testosterone, muscle androgen receptor protein levels, muscle glycogen, or serum creatine kinase). Regression analysis indicated PRE type II fiber percentage (R2 = 0.152, β = 0.390, p = 0.033) and PRE type II fCSA (R2 = 0.207, β = -0.455, p = 0.019) best predicted the PRE-to-W6 change in the composite hypertrophy score. While our sample size is limited, these data suggest: (a) HIGH responders may exhibit more growth potential given that they possessed lower PRE type II fCSA values and (b) possessing a greater type II fiber percentage as a trained individual may be advantageous for hypertrophy in response to resistance training

Bovine Milk Extracellular Vesicles (EVs) Modification Elicits Skeletal Muscle Growth in Rats

The current study investigated how bovine milk extracellular vesicles (EVs) affected rotarod performance and biomarkers of skeletal muscle physiology in young, growing rats. Twenty-eight-day Fisher 344 rats were provided an AIN-93G-based diet for 4 weeks that either remained unadulterated [EVs and RNA-sufficient (ERS; n = 12)] or was sonicated [EVs and RNA-depleted (ERD; n = 12)]. Prior to (PRE) and on the last day of the intervention (POST), animals were tested for maximal rotarod performance. Following the feeding period, the gastrocnemius muscle was analyzed at the histological, biochemical, and molecular levels and was also used to measure mitochondrial function and reactive oxygen species (ROS) emission. A main effect of time was observed for rotarod time (PRE &gt; POST, p = 0.001). Terminal gastrocnemius mass was unaffected by diet, although gastrocnemius muscle fiber cross sectional area was 11% greater (p = 0.018) and total RNA (a surrogate of ribosome density) was 24% greater (p = 0.001) in ERD. Transcriptomic analysis of the gastrocnemius indicated that 22 mRNAs were significantly greater in ERS versus ERD (p &lt; 0.01), whereas 55 mRNAs were greater in ERD versus ERS (p &lt; 0.01). There were no differences in gastrocnemius citrate synthase activity or mitochondrial coupling (respiratory control ratio), although mitochondrial ROS production was lower in ERD gastrocnemius (p = 0.016), which may be explained by an increase in glutathione peroxidase protein levels (p = 0.020) in ERD gastrocnemius. Dietary EVs profiling confirmed that sonication in the ERD diet reduced EVs content by ∼60%. Our findings demonstrate that bovine milk EVs depletion through sonication elicits anabolic and transcriptomic effects in the gastrocnemius muscle of rapidly maturing rats. While this did not translate into a functional outcome between diets (i.e., rotarod performance), longer feeding periods may be needed to observe such functional effects

An intron variant of the GLI family zinc finger 3 (GLI3) gene differentiates resistance training-induced muscle fiber hypertrophy in younger men

We examined the association between genotype and resistance training-induced changes (12 wk) in dual x-ray energy absorptiometry (DXA)-derived lean soft tissue mass (LSTM) as well as muscle fiber cross-sectional area (fCSA; vastus lateralis; n = 109; age = 22 ± 2 y, BMI = 24.7 ± 3.1 kg/m2). Over 315 000 genetic polymorphisms were interrogated from muscle using DNA microarrays. First, a targeted investigation was performed where single nucleotide polymorphisms (SNP) identified from a systematic literature review were related to changes in LSTM and fCSA. Next, genome-wide association (GWA) studies were performed to reveal associations between novel SNP targets with pre- to post-training change scores in mean fCSA and LSTM. Our targeted investigation revealed no genotype-by-time interactions for 12 common polymorphisms regarding the change in mean fCSA or change in LSTM. Our first GWA study indicated no SNP were associated with the change in LSTM. However, the second GWA study indicated two SNP exceeded the significance level with the change in mean fCSA (P = 6.9 × 10–7 for rs4675569, 1.7 × 10–6 for rs10263647). While the former target is not annotated (chr2:205936846 (GRCh38.p12)), the latter target (chr7:41971865 (GRCh38.p12)) is an intron variant of the GLI Family Zinc Finger 3 (GLI3) gene. Follow-up analyses indicated fCSA increases were greater in the T/C and C/C GLI3 genotypes than the T/T GLI3 genotype (P \u3c.05). Data from the Auburn cohort also revealed participants with the T/C and C/C genotypes exhibited increases in satellite cell number with training (P \u3c.05), whereas T/T participants did not. Additionally, those with the T/C and C/C genotypes achieved myonuclear addition in response to training (P \u3c.05), whereas the T/T participants did not. In summary, this is the first GWA study to examine how polymorphisms associate with the change in hypertrophy measures following resistance training. Future studies are needed to determine if the GLI3 variant differentiates hypertrophic responses to resistance training given the potential link between this gene and satellite cell physiology

A yeast two-hybrid system reconstituting substrate recognition of the von Hippel-Lindau tumor suppressor protein

The von Hippel-Lindau tumor suppressor protein (pVHL) is inactivated in the hereditary cancer syndrome von Hippel-Lindau disease and in the majority of sporadic renal carcinomas. pVHL is the substrate-binding subunit of the CBCVHL ubiquitin ligase complex that negatively regulates cell growth by promoting the degradation of hypoxia-inducible transcription factor subunits (HIF1/2α). Proteomics-based identification of novel pVHL substrates is hampered by their short half-life and low abundancy in mammalian cells. The usefulness of yeast two-hybrid (Y2H) approaches, on the other hand, has been limited by the failure of pVHL to adopt its native structure and by the absence of prolylhydroxylase activity critical for pVHL substrate recognition. Therefore, we modified the Y2H system to faithfully reconstitute the physical interaction between pVHL and its substrates. Our approach relies on the coexpression of pVHL with the cofactors Elongin B and Elongin C and with HIF1/2α prolylhydroxylases. In a proof-of-principle Y2H screen, we identified the known substrates HIF1/2α and new candidate substrates including diacylglycerol kinase iota, demonstrating that our strategy allows detection of stable interactions between pVHL and otherwise elusive cellular targets. Additional future applications may include structure/function analyses of pVHL-HIF1/2α binding and screens for therapeutically relevant compounds that either stabilize or disrupt this interaction

Epigenetic expansion of VHL-HIF signal output drives multiorgan metastasis in renal cancer.

Inactivation of the von Hippel-Lindau tumor suppressor gene, VHL, is an archetypical tumor-initiating event in clear cell renal carcinoma (ccRCC) that leads to the activation of hypoxia-inducible transcription factors (HIFs). However, VHL mutation status in ccRCC is not correlated with clinical outcome. Here we show that during ccRCC progression, cancer cells exploit diverse epigenetic alterations to empower a branch of the VHL-HIF pathway for metastasis, and the strength of this activation is associated with poor clinical outcome. By analyzing metastatic subpopulations of VHL-deficient ccRCC cells, we discovered an epigenetically altered VHL-HIF response that is specific to metastatic ccRCC. Focusing on the two most prominent pro-metastatic VHL-HIF target genes, we show that loss of Polycomb repressive complex 2 (PRC2)-dependent histone H3 Lys27 trimethylation (H3K27me3) activates HIF-driven chemokine (C-X-C motif) receptor 4 (CXCR4) expression in support of chemotactic cell invasion, whereas loss of DNA methylation enables HIF-driven cytohesin 1 interacting protein (CYTIP) expression to protect cancer cells from death cytokine signals. Thus, metastasis in ccRCC is based on an epigenetically expanded output of the tumor-initiating pathway

Inside and out: the activities of senescence in cancer.

The core aspect of the senescent phenotype is a stable state of cell cycle arrest. However, this is a disguise that conceals a highly active metabolic cell state with diverse functionality. Both the cell-autonomous and the non-cell-autonomous activities of senescent cells create spatiotemporally dynamic and context-dependent tissue reactions. For example, the senescence-associated secretory phenotype (SASP) provokes not only tumour-suppressive but also tumour-promoting responses. Senescence is now increasingly considered to be an integrated and widespread component that is potentially important for tumour development, tumour suppression and the response to therapy.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/nrc377

Classification of current anticancer immunotherapies

© 2014. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.info:eu-repo/semantics/publishedVersio