Differential Tissue Response to Growth Hormone in Mice

Growth hormone (GH) has been shown to act directly on multiple tissues throughout the body. Historically, it was believed that GH acted directly in the liver and only indirectly in other tissues via insulin‐like growth hormone 1 (IGF‐1). Despite extensive work to describe GH action in individual tissues, a comparative analysis of acute GH signaling in key metabolic tissues has not been performed. Herein, we address this knowledge gap. Acute tissue response to human recombinant GH was assessed in mice by measuring signaling via phospho‐STAT5 immunoblotting. STAT5 activation is an easily and reliably detected early marker of GH receptor engagement. We found differential tissue sensitivities; liver and kidney were equally GH‐sensitive and more sensitive than white adipose tissue, heart, and muscle (gastrocnemius). Gastrocnemius had the greatest maximal response compared to heart, liver, white adipose tissue, and whole kidney. Differences in maximum responsiveness were positively correlated with tissue STAT5 abundance, while differences in sensitivity were not explained by differences in GH receptor levels. Thus, GH sensitivity and responsiveness of distinct metabolic tissues differ and may impact physiology and disease

Effects of Time-Restricted Exercise on Training Induced Adaptations in Mice

Recent studies have shown that the time of day that exercise is performed can alter the physiological and molecular response. However, very few studies have investigated the longitudinal effects of time-of-day dependent training. Identification of an optimal exercise timing could lead to subsequent exercise prescriptions to elicit specific adaptations based on desired outcomes in healthy or disease populations. PURPOSE: The purpose of this study was to determine if voluntary exercise performed at different times of day would alter the physiological response to training. METHODS: Male C57BL/6 mice (Jackson Labs) housed on a strict 12:12 light dark cycle performed 4 weeks of voluntary exercise training on a wireless running wheel, in a time-of-day dependent manner. Mice were allocated to three groups (n = 10/group): 1) Sedentary (locked wheel), 2) Early Active Phase exercise (EAP; wheel unlocked during the first half of the dark/active phase), or 3) Late Active Phase exercise (LAP; wheel unlocked during the second half of the dark/active phase). Endurance capacity was tested via graded exercise tests (GXTs) at baseline, 2- and 4-weeks. Body weight was recorded at the same times. RESULTS: We found the EAP mice accrued significantly more voluntary exercise compared to LAP mice (7.34 ± 0.55 km/session vs 4.70 ± 0.38 km/session, p \u3c 0.001). Interestingly, EAP and LAP mice both improved on the GXT to a similar extent, and both performed significantly better than SED mice (537.2 ± 68.3 m, vs 467.6 ± 27.7 m, vs 262.7 ± 15.3 m, respectively; p \u3c 0.05). Throughout the training period, SED and EAP mice gained similar amounts of weight, while LAP mice gained less weight (1.4 ± 0.2 g, vs 0.4 ± 0.4 g, vs 1.3 ± 0.3 g, respectively). CONCLUSION: Based on these findings, mice preferentially perform nearly 50% more exercise during the early active phase compared to the late active phase. However, no significant difference exists in the GXT performance between EAP and LAP mice. These findings suggest that LAP exercise may confer similar adaptations with substantially lower volume

Effects of Social Jetlag on Exercise-Induced Adaptations in Skeletal Muscle Mitochondrial Content in Mice

Social jetlag (SJL) occurs when the sleep/wake schedule differs on work days (weekdays) and free days (weekends). Previous studies have shown that individuals with SJL have lower physical fitness and are prone to obesity. While exercise reverses this phenotype (i.e. - via increasing skeletal muscle mitochondrial content), the effects of social jetlag on exercise training adaptations have yet to be shown. PURPOSE: To determine how social jetlag impacts skeletal muscle adaptations to exercise training in mice. METHODS: Male C57BL/6J mice aged 10-weeks (n=40) were assigned to four groups, with experimental conditions persisting for 6-weeks; control sedentary (C-SED), control with voluntary wheel exercise (C-EX), social jetlag sedentary (SJL-SED), and social jetlag with exercise (SJL-EX). SJL was introduced weekly via 4h shifts in light/dark cycles on weekends. Skeletal muscles (quad, gas, sol) were collected for gravimetric analysis, and assessment of circadian clock gene expression and mitochondrial content. RESULTS: Mice with SJL had larger quadriceps (ME-SJL, p\u3c0.05), but this effect was lost when normalized to BW. Exercised mice had smaller quadriceps (ME-EX, p\u3c0.05), and larger solei (ME-EX, p\u3c0.05). No effects of SJL were seen in solei. SJL led to alterations in PER1, PER2, and CRY2 expression (ME-SJL, p\u3c0.05 all), while exercise led to reductions in PER2 and CRY2 expression (ME-EX, p\u3c0.05), with no interactions reaching significance. Exercise increased OXPHOS complex expression (ME Exercise; C-V, C-III, C-I, all p\u3c0.05), which was attenuated by SJL (ME SJL; C-II, C-I, p\u3c0.05). We found an interaction in C-IV expression where the exercise-induced increase was blunted in SJL-EX mice (p\u3c0.05). CONCLUSION: These data suggest that, while exercise has a beneficial impact on mitochondrial content in skeletal muscle, social jetlag prevents some of the exercise-induced improvements, potentially via disruption of the muscle circadian clock

Social Jetlag Inhibits Exercise-Induced Adaptations in the Heart and Alters Markers of Mitochondrial Dynamics

Social jetlag (SJL), or the shifting of behavior and sleep times between weekdays and weekends, is a pervasive form of circadian rhythm disruption that affects nearly 70% of the population to some extent. The magnitude of SJL can be determined by the difference in the mid-sleep phase between weekends and weekdays. Higher levels of SJL have been associated with lower levels of cardiorespiratory fitness, and increased incidence of cardiometabolic disease, which may be due, in part, to mitochondrial dysfunction. However, no studies to date have evaluated the effects of long term SJL on cardiac mitochondrial dynamics. PURPOSE: To determine the effect of SJL on mitochondrial fission and fusion signaling in the heart, and if exercise protects the heart against SJL. METHODS: Male C57BL/6 mice (n = 40) were allocated to four groups (n = 10/group): 1) Control Light:Dark cycle, Sedentary (CON-SED), 2) Control Light:Dark cycle, Exercise (CON-EX), 3) SJL, sedentary (SJL-SED), or SJL, exercise (SJL-EX). SJL was implemented by delaying the LD cycle 4 hours on ‘Fridays,’ and advancing the LD cycle on Mondays. Exercise was provided ad libitum with a disc. Conditions persisted for 6 weeks at which point hearts were harvested for gravimetric analysis and western blotting of markers of mitochondrial dynamics. RESULTS: Exercise caused myocardial hypertrophy in both control and SJL LD conditions (Main Effect – EX, p \u3c 0.05), with no difference between CON and SJL conditions. We did not observe any significant differences in mitochondrial content (OXPHOS antibody cocktail, p \u3e 0.05), SJL decreased expression of mitochondrial fusion proteins MFN1 and OPA1 (Main Effect – SJL, p \u3c 0.05). Importantly, SJL inhibited exercise-induced increases in MFN2 (p \u3c 0.05), suggesting that SJL specifically ameliorates some exercise-induced adaptations in mitochondrial dynamics in the heart. CONCLUSION: These findings suggest that exercise induces adaptations in mitochondrial dynamics, potentially increasing mitochondrial function, and SJL may disrupt mitochondrial dynamics both in the sedentary and exercise trained states

Assessing the Validity of Several Heart Rate Monitors in Wearable Technology While Mountain Biking

International Journal of Exercise Science 16(7): 1440-1450, 2023. Purpose: This study sought to assess the validity of several heart rate (HR) monitors in wearable technology during mountain biking (MTB), compared to the Polar H7® HR monitor, used as the criterion device. Methods: A total of 20 participants completed two MTB trials while wearing six HR monitors (5 test devices, 1 criterion). HR was recorded on a second-by-second basis for all devices analyzed. After data processing, validity measures were calculated, including 1. error analysis: mean absolute percentage errors (MAPE), mean absolute error (MAE), and mean error (ME), and 2. Correlation analysis: Lin’s concordance correlation coefficient (CCC) and Pearson’s correlation coefficient (r). Thresholds for validity were set at MAPE \u3c 10% and CCC \u3e 0.7. Results: The only device that was found to be valid during mountain biking was the Suunto Spartan Sport watch with accompanying HR monitor, with a MAPE of 0.66% and a CCC of 0.99 for the overall, combined data. Conclusion: If a person would like to track their HR during mountain biking, for pacing, training, or other reasons, the devices best able to produce valid results are chest-based, wireless electrocardiogram (ECG) monitors, secured by elastic straps to minimize the movement of the device, such as the Suunto chest-based HR monitor

Validity and Reliability of Three Commercially Available Smart Sports Bras during Treadmill Walking and Running

A variety of wearable technology devices report heart rate. Heart rate sensing smart bras are manufactured for females who participate in activity, however accuracy has not been determined. The purpose was to determine the validity of heart rate measures in three commercially available sports bras during walking and running. Twenty-four healthy females completed bouts of treadmill exercise. The Adidas Smart sports bra, Berlei sports bra, and Sensoria Fitness biometric sports bra were tested. Participant perception of each garment was obtained immediately after the participant divested the sports bra. The Adidas Smart sports bra was valid only during rest (Intraclass correlation Coefficient [ICC] = 0.79, mean absolute percentage error [MAPE] = 4.5%, Limits of Agreement [LoA]=−8 to 8). The Berlei sports bra was valid across all conditions (ICC = 0.99, MAPE = 0.66%, LoA = −19 to 19), and the Sensoria biometric bra was valid during rest and walking (ICC = 0.96, MAPE = 1.9%, LoA = −15 to 12). Perception of the smart sports bras was higher for the Adidas Smart sports bra and Sensoria Fitness sports bra, and lower for the Berlei sports bra. Sports bra manufacturers designing wearable technology garments must consider the ability of returning accurate biometric data while providing necessary function and comfort to females engaging in physical activity

Effects of Acute Dietary Polyphenols and Post-Meal Physical Activity on Postprandial Metabolism in Adults with Features of the Metabolic Syndrome

Approximately 22% of U.S. adults and 25% of adults globally have metabolic syndrome (MetS). Key features, such as dysglycemia and dyslipidemia, predict type 2 diabetes, cardiovascular disease, premature disability, and death. Acute supplementation of dietary polyphenols and post-meal physical activity hold promise in improving postprandial dysmetabolism. To our knowledge, no published review has described the effects of either intervention on postprandial glucose, insulin, lipids, and markers of oxidative damage and inflammation in adults with features of MetS. Thus, we conducted this review of controlled clinical trials that provided dietary polyphenols from oils, fruits, teas, and legumes during a dietary challenge, or implemented walking, cycling, and stair climbing and descending after a dietary challenge. Clinical trials were identified using ClinicalTrials.gov, PubMed, and Google Scholar and were published between 2000 and 2019. Dietary polyphenols from extra virgin olive oil, grapes, blackcurrants, strawberries, black tea, and black beans improved postprandial glucose, insulin, and markers of oxidative damage and inflammation, but results were not consistent among clinical trials. Freeze-dried strawberry powder distinctly improved postprandial insulin and markers of oxidative damage and inflammation. Post-meal physical activity attenuated postprandial glucose, but effects on postprandial lipids and markers of oxidative damage and inflammation were inconclusive. Consuming dietary polyphenols with a meal and completing physical activity after a meal may mitigate postprandial dysmetabolism in adults with features of MetS

Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.Comment: 17 pages, 3 figures, 3 tables. Final manuscript accepted for publication in Phys. Lett. B. Parts of the text slightly expanded or rearranged; results are unchange

A Study of \bar{p}p -> Two Neutral Pseudoscalar Mesons at the chi_c0(1^3P_0) Formation Energy

Fermilab experiment E835 has studied reactions \bar{p}p -> pi0 pi0, pi0 eta, eta eta, pi0 eta' and eta eta' in the energy region of the chi_c0(1^3P_0) from 3340 MeV to 3470 MeV. Interference between resonant and continuum production is observed in the pi0 pi0 and eta eta channels, and the product of the input and output branching fractions is measured. Limits on resonant production are set for the pi0 eta and pi0 eta' channels. An indication of interference is observed in the eta eta' channel. The technique for extracting resonance parameters in an environment dominated by continuum production is described.Comment: 15 pages, 21 figures, submitted Phys. Rev.

Measurement of the Resonance Parameters of the χ1(13P1)\chi_{1}(1^3P_1) and χ2(13P2)\chi_{2}(1^3P_2) States of Charmonium formed in Antiproton-Proton Annihilations

We have studied the $^3P_J$ ($\chi_c)$ states of charmonium in formation by antiproton-proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and $B(\chi_{cJ} \to \bar{p} p) \times \Gamma(\chi_{cJ} \to J/\psi + anything)$ for the $\chi_{c1}$ and $\chi_{c2}$ by means of the inclusive reaction $\bar{p}p \to \chi_{cJ} \to J/\psi + anything \to (e^{+}e^{-}) +anything$. Using the subsample of events where $\chi_{cJ} \to \gamma + J/\psi \to \gamma + (e^{+}e^{-})$ is fully reconstructed, we derive $B(\chi_{cJ} \to \bar p p)\times \Gamma(\chi_{cJ} \to J/\psi + \gamma)$. We summarize the results of the E760 (updated) and E835 measurements of mass, width and $B(\chi_{cJ} \to \bar{p}p) \Gamma(\chi_{cJ} \to J/\psi+\gamma)$ (J=0,1,2) and discuss the significance of these measurements