Level of dietary protein intake affects glucose turnover in endurance-trained men

<p>Abstract</p> <p>Background</p> <p>To examine the effects of higher-protein diets on endogenous glucose metabolism in healthy, physically active adults, glucose turnover was assessed in five endurance-trained men (age 21.3 ± 0.3 y, VO_2peak70.6 ± 0.1 mL kg^-1min^-1) who consumed dietary protein intakes spanning the current dietary reference intakes.</p> <p>Findings</p> <p>Using a randomized, crossover design, volunteers consumed 4 week eucaloric diets providing either a low (0.8 g kg^-1d^-1; LP), moderate (1.8 g kg^-1d^-1; MP), or high (3.6 g kg^-1d^-1; HP) level of dietary protein. Glucose turnover (Ra, glucose rate of appearance; and Rd glucose rate of disappearance) was assessed under fasted, resting conditions using primed, constant infusions of [6,6-²H₂] glucose. Glucose Ra and Rd (mg kg^-1min^-1) were higher for MP (2.8 ± 0.1 and 2.7 ± 0.1) compared to HP (2.4 ± 0.1 and 2.3 ± 0.2, <it>P </it>< 0.05) and LP (2.3 ± 0.1 and 2.2 ± 0.1, <it>P </it>< 0.01) diets. Glucose levels (mmol/L) were not different (<it>P </it>> 0.05) between LP (4.6 ± 0.1), MP (4.8 ± 0.1), and HP (4.7 ± 0.1) diets.</p> <p>Conclusions</p> <p>Level of protein consumption influenced resting glucose turnover in endurance athletes in a state of energy balance with a higher rate of turnover noted for a protein intake of 1.8 g kg^-1d^-1. Findings suggest that consumption of protein in excess of the recommended dietary allowance but within the current acceptable macronutrient distribution range may contribute to the regulation of blood glucose when carbohydrate intake is reduced by serving as a gluconeogenic substrate in endurance-trained men.</p

New models and online calculator for predicting non-sentinel lymph node status in sentinel lymph node positive breast cancer patients

<p>Abstract</p> <p>Background</p> <p>Current practice is to perform a completion axillary lymph node dissection (ALND) for breast cancer patients with tumor-involved sentinel lymph nodes (SLNs), although fewer than half will have non-sentinel node (NSLN) metastasis. Our goal was to develop new models to quantify the risk of NSLN metastasis in SLN-positive patients and to compare predictive capabilities to another widely used model.</p> <p>Methods</p> <p>We constructed three models to predict NSLN status: recursive partitioning with receiver operating characteristic curves (RP-ROC), boosted Classification and Regression Trees (CART), and multivariate logistic regression (MLR) informed by CART. Data were compiled from a multicenter Northern California and Oregon database of 784 patients who prospectively underwent SLN biopsy and completion ALND. We compared the predictive abilities of our best model and the Memorial Sloan-Kettering Breast Cancer Nomogram (Nomogram) in our dataset and an independent dataset from Northwestern University.</p> <p>Results</p> <p>285 patients had positive SLNs, of which 213 had known angiolymphatic invasion status and 171 had complete pathologic data including hormone receptor status. 264 (93%) patients had limited SLN disease (micrometastasis, 70%, or isolated tumor cells, 23%). 101 (35%) of all SLN-positive patients had tumor-involved NSLNs. Three variables (tumor size, angiolymphatic invasion, and SLN metastasis size) predicted risk in all our models. RP-ROC and boosted CART stratified patients into four risk levels. MLR informed by CART was most accurate. Using two composite predictors calculated from three variables, MLR informed by CART was more accurate than the Nomogram computed using eight predictors. In our dataset, area under ROC curve (AUC) was 0.83/0.85 for MLR (n = 213/n = 171) and 0.77 for Nomogram (n = 171). When applied to an independent dataset (n = 77), AUC was 0.74 for our model and 0.62 for Nomogram. The composite predictors in our model were the product of angiolymphatic invasion and size of SLN metastasis, and the product of tumor size and square of SLN metastasis size.</p> <p>Conclusion</p> <p>We present a new model developed from a community-based SLN database that uses only three rather than eight variables to achieve higher accuracy than the Nomogram for predicting NSLN status in two different datasets. </p

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1\% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay $Q$-value for the nEXO design

The effects of precooling on thermoregulation during subsequent exercise in the heat

The purpose of this study was to lower body core temperature prior to a simulated portion of a triathlon (swim-15min; bike-45min) and examine whether precooling could attenuate thermal strain and increase subjective exercise tolerance in the heat. Six endurance trained triathletes (mean ± SE, 28 ± 2 yr, 8.2 ± 1.7 % body fat) completed two randomly-assigned trials, one week apart. The precooling trial (PC) involved lowering body core temperature (-0.5°C) in water prior to swimming and cycling. The control trial (CON) was identical except no precooling was performed. Water temperature and environmental conditions were maintained at -25.6°C and -26.6°C/60% RH respectively, throughout all testing. Mean time to precool was 31:37 ± 8:03 and average time to reach baseline temperature during cycling was 9:35 ± 7:60. Oxygen consumption (VO2), heart rate (HR), rate of perceived exertion (RPE), thermal sensation (TS), and skin (Tsk) and core (Ta) temperatures were recorded following the swim segment and throughout cycling. No significant differences in mean body (TO or Tsk were noted between PC and CON, but a significant difference (P<0.05) in T, between treatments was noted through the early phases of cycling. No significant differences were reported in HR, V02, RPE, TS or sweat rate (SR) between treatments. Body heat storage (S) was negative following swimming in both PC (92 ± 6 W/m2) and CON (66 ± 9 W/m2). A greater increase in S occurred in PC (109 ± 6 W/m2) vs. CON (79 ±4 W/m2) during cycling (P<0.05) . Precooling attenuated the rise in T,, but this effect was transient. Based on the results from this study, precooling is not recommended prior to endurance exercise in the heat.Thesis (M.S.)School of Physical Educatio

The effects of precooling on thermoregulation during subsequent exercise in the heat

The purpose of this study was to lower body core temperature prior to a simulated portion of a triathlon (swim-15min; bike-45min) and examine whether precooling could attenuate thermal strain and increase subjective exercise tolerance in the heat. Six endurance trained triathletes (mean ± SE, 28 ± 2 yr, 8.2 ± 1.7 % body fat) completed two randomly-assigned trials, one week apart. The precooling trial (PC) involved lowering body core temperature (-0.5°C) in water prior to swimming and cycling. The control trial (CON) was identical except no precooling was performed. Water temperature and environmental conditions were maintained at -25.6°C and -26.6°C/60% RH respectively, throughout all testing. Mean time to precool was 31:37 ± 8:03 and average time to reach baseline temperature during cycling was 9:35 ± 7:60. Oxygen consumption (VO2), heart rate (HR), rate of perceived exertion (RPE), thermal sensation (TS), and skin (Tsk) and core (Ta) temperatures were recorded following the swim segment and throughout cycling. No significant differences in mean body (TO or Tsk were noted between PC and CON, but a significant difference (P<0.05) in T, between treatments was noted through the early phases of cycling. No significant differences were reported in HR, V02, RPE, TS or sweat rate (SR) between treatments. Body heat storage (S) was negative following swimming in both PC (92 ± 6 W/m2) and CON (66 ± 9 W/m2). A greater increase in S occurred in PC (109 ± 6 W/m2) vs. CON (79 ±4 W/m2) during cycling (P<0.05) . Precooling attenuated the rise in T,, but this effect was transient. Based on the results from this study, precooling is not recommended prior to endurance exercise in the heat.School of Physical EducationThesis (M.S.

Immediate response of mammalian target of rapamycin (mTOR)-mediated signalling following acute resistance exercise in rat skeletal muscle

The purpose of the present investigation was to determine whether mammalian target of rapamycin (mTOR)-mediated signalling and some key regulatory proteins of translation initiation are altered in skeletal muscle during the immediate phase of recovery following acute resistance exercise. Rats were operantly conditioned to reach an illuminated bar located high on a Plexiglass cage, such that the animals completed concentric and eccentric contractions involving the hindlimb musculature. Gastrocnemius muscle was extracted immediately after acute exercise and 5, 10, 15, 30 and 60 min of recovery. Phosphorylation of protein kinase B (PKB) on Ser-473 peaked at 10 min of recovery (282 % of control, P < 0.05) with no significant changes noted for mTOR phosphorylation on Ser-2448. Eukaryotic initiation factor (eIF) 4E-binding protein-1 (4E-BP1) and S6 kinase-1 (S6K1), both downstream effectors of mTOR, were altered during recovery as well. 4E-BP1 phosphorylation was significantly elevated at 10 min (292 %, P < 0.01) of recovery. S6K1 phosphorylation on Thr-389 demonstrated a trend for peak activation at 10 min following exercise (336 %, P = 0.06) with ribosomal protein S6 phosphorylation being maximally activated at 15 min of recovery (647 %, P < 0.05). Components of the eIF4F complex were enhanced during recovery as eIF4E association with eIF4G peaked at 10 min (292 %, P < 0.05). Events regulating the binding of initiator methionyl-tRNA to the 40S ribosomal subunit were assessed through eIF2B activity and eIF2α phosphorylation on Ser-51. No differences were noted with either eIF2B or eIF2α. Collectively, these results provide strong evidence that mTOR-mediating signalling is transiently upregulated during the immediate period following resistance exercise and this response may constitute the most proximal growth response of the cell

Differential Responses of Blood Essential Amino Acid Levels Following Ingestion of High-Quality Plant-Based Protein Blends Compared to Whey Protein—A Double-Blind Randomized, Cross-Over, Clinical Trial

This study assessed the bio-equivalence of high-quality, plant-based protein blends versus Whey Protein Isolate (WPI) in healthy, resistance-trained men. The primary endpoint was incremental area under the curve (iAUC) of blood essential Amino Acids (eAAs) 4 hours after consumption of each product. Maximum concentration (Cmax) and time to maximum concentration (Tmax) of blood leucine were secondary outcomes. Subjects (n = 18) consumed three plant-based protein blends and WPI (control). An analysis of Variance model was used to assess for bio-equivalence of total sum of blood eAA concentrations. The total blood eAA iAUC ratios of the three blends were [90% CI]: #1: 0.66 [0.58&ndash;0.76]; #2: 0.71 [0.62&ndash;0.82]; #3: 0.60 [0.52&ndash;0.69], not completely within the pre-defined equivalence range [0.80&ndash;1.25], indicative of 30&ndash;40% lower iAUC versus WPI. Leucine Cmax of the three blends was not equivalent to WPI, #1: 0.70 [0.67&ndash;0.73]; #2: 0.72 [0.68&ndash;0.75]; #3: 0.65 [0.62&ndash;0.68], indicative of a 28&ndash;35% lower response. Leucine Tmax for two blends were similar to WPI (#1: 0.94 [0.73&ndash;1.18]; #2: 1.56 [1.28&ndash;1.92]; #3: 1.19 [0.95&ndash;1.48]). The plant-based protein blends were not bio-equivalent. However, blood leucine kinetic data across the blends approximately doubled from fasting concentrations, whereas blood Tmax data across two blends were similar to WPI. This suggests evidence of rapid hyperleucinemia, which correlates with a protein&rsquo;s anabolic potential