Muscle Mitochondrial Function at Different Phases of the Menstrual Cycle

The effect of menstrual cycle (MC) phase on muscle recovery from damage has been studied using markers of strength and soreness, but remains inconclusive. Mitochondrial function is essential for muscle recovery, and has been found to be influenced by estradiol (E2). Understanding the relationship between MC phase and mitochondria can provide further insight into women’s muscle health. The PURPOSE of this study was to determine how MC phase affects markers of muscle damage and recovery, with emphasis on mitochondrial function, following electrically-stimulated muscle contractions. METHODS: 22 premenopausal females were recruited and split into two groups, early follicular (EF) and late follicular (LF). After menstrual cycle tracking and phase confirmation, subjects performed a baseline maximum voluntary knee extension contraction (MVC) and provided a muscle biopsy one week prior to test day. On test day, subjects underwent 200 electrically stimulated eccentric muscle contractions (ES). Subjects reported for follow-up strength tests on days 2, 4, and 7 post damage, and gave a final biopsy on day 7. RESULTS: MVC decreased an average of 14 ± 6% immediately following ES and recovered to 6 ± 7% below baseline by day 4, with no differences between groups for percent decrease in MVC (p=.67). Average peak soreness was 4.0 ± 1.9, with no differences between groups (p=.91). Average change in max coupled mitochondrial respiration was -14.3 ± 15.5 pmolO2ᐧs-1ᐧmg-1 for the EF group and 1.3 ± 22.3 pmolO2ᐧs-1ᐧmg-1 for the LF group (p=.03). Average change in fatty acid supported respiration was -3.6 ± 7.4 pmolO2ᐧs-1ᐧmg-1 for the EF group and 7.5 ± 10.5 pmolO2ᐧs-1ᐧmg-1 for the LF group (p=.046). However, these results are complicated by baseline differences in respiration, with max coupled respiration being significantly higher (p=.02) in the mid-luteal phase (EF group baseline) than the early-follicular phase (LF group baseline). CONCLUSIONS: Results show novel findings that baseline mitochondrial respiration and mitochondrial response to damage differ between MC phases. This finding supports previous research relating mitochondrial function and E2 levels, and suggests further research on mitochondrial function throughout the menstrual cycle

An intercomparison study of four different techniques for measuring the chemical composition of nanoparticles

Currently, the complete chemical characterization of nanoparticles (< 100 nm) represents an analytical challenge, since these particles are abundant in number but have negligible mass. Several methods for particle-phase characterization have been recently developed to better detect and infer more accurately the sources and fates of sub-100 nm particles, but a detailed comparison of different approaches is missing. Here we report on the chemical composition of secondary organic aerosol (SOA) nanoparticles from experimental studies of α-pinene ozonolysis at −50, −30, and −10 ∘C and intercompare the results measured by different techniques. The experiments were performed at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). The chemical composition was measured simultaneously by four different techniques: (1) thermal desorption–differential mobility analyzer (TD–DMA) coupled to a NO$^-_3$ chemical ionization–atmospheric-pressure-interface–time-of-flight (CI–APi–TOF) mass spectrometer, (2) filter inlet for gases and aerosols (FIGAERO) coupled to an I$^−$ high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS), (3) extractive electrospray Na$^+$ ionization time-of-flight mass spectrometer (EESI-TOF), and (4) offline analysis of filters (FILTER) using ultra-high-performance liquid chromatography (UHPLC) and heated electrospray ionization (HESI) coupled to an Orbitrap high-resolution mass spectrometer (HRMS). Intercomparison was performed by contrasting the observed chemical composition as a function of oxidation state and carbon number, by estimating the volatility and comparing the fraction of volatility classes, and by comparing the thermal desorption behavior (for the thermal desorption techniques: TD–DMA and FIGAERO) and performing positive matrix factorization (PMF) analysis for the thermograms. We found that the methods generally agree on the most important compounds that are found in the nanoparticles. However, they do see different parts of the organic spectrum. We suggest potential explanations for these differences: thermal decomposition, aging, sampling artifacts, etc. We applied PMF analysis and found insights of thermal decomposition in the TD–DMA and the FIGAERO

The Effect of Heat Therapy on Skeletal Muscle Satellite Cell Content

Satellite cells are essential for proper muscle repair and adaptation. Studies have shown that exercise can lead to an increase in satellite cell content within muscle tissue. However, it is unknown whether other environmental stressors, such as heat, are also capable of augmenting the satellite cell pool. PURPOSE: The purpose of this study was to quantify changes in satellite cell content before and after 6-weeks (3x/wk) of skeletal muscle heat therapy (HT) or single leg knee extension exercise training (EX). Additionally, a sham heat treatment was used as a control. We hypothesized that HT would result in an increase in satellite cell content, though to a lesser extent than the EX group. METHODS: We randomized 28 sedentary but otherwise healthy, young adults (ages 18-36; n = 13 female, n = 15 male) to receive either HT (2 hr, 3 days/wk, 6-week period), EX (40 min, 3 days/wk, 6-week period), or sham heating sessions (CON; 2hr, 3 days/wk, 6-week period). The HT was administered through pulsed, shortwave diathermy. Muscle biopsies were taken from the vastus lateralis at baseline, after 3 weeks of intervention, and again after 6 weeks of intervention. RESULTS: For the Control Group, satellite cell count per mm2 at baseline = 8.107 (± 0.4799), at 3 weeks = 10.27 (± 0.911), at 6 weeks = 9.84 (± 0.675). For the EX Group, satellite cell count per mm2 at baseline = 9.705 (± 1.27), at 3 weeks = 10.87 (± 1.12), and at 6 weeks = 10.47 (±0.7997). For the HT Group, satellite cell count per mm2 at baseline = 8.535 (± 0.582), at 3 weeks = 11.54 (± 1.43), and at 6 weeks = 10.202 (± 0.940). Statistical analysis indicated a significant main effect of time (p=0.0125), but no significant effect of group (p=0.5504) or the group x time interaction (p=0.8412). CONCLUSION: Our findings suggest that 6 weeks of HT is insufficient to affect the satellite cell content within muscle fibers. This study provides additional insight in the literature about the effects of HT on human subjects

The Effect of Heat Therapy on Skeletal Muscle Satellite Cell Content

Satellite cells are essential for proper muscle repair and adaptation. Studies have shown that exercise can lead to an increase in satellite cell content within muscle tissue. However, it is unknown whether other environmental stressors, such as heat, are also capable of augmenting the satellite cell pool. PURPOSE: The purpose of this study was to quantify changes in satellite cell content before and after 6-weeks (3x/wk) of skeletal muscle heat therapy (HT) or single leg knee extension exercise training (EX). Additionally, a sham heat treatment was used as a control. We hypothesized that HT would result in an increase in satellite cell content, though to a lesser extent than the EX group. METHODS: We randomized 28 sedentary but otherwise healthy, young adults (ages 18-36; n = 13 female, n = 15 male) to receive either HT (2 hr, 3 days/wk, 6-week period), EX (40 min, 3 days/wk, 6-week period), or sham heating sessions (CON; 2hr, 3 days/wk, 6-week period). The HT was administered through pulsed, shortwave diathermy. Muscle biopsies were taken from the vastus lateralis at baseline, after 3 weeks of intervention, and again after 6 weeks of intervention. RESULTS: For the Control Group, satellite cell count per mm2 at baseline = 8.107 (± 0.4799), at 3 weeks = 10.27 (± 0.911), at 6 weeks = 9.84 (± 0.675). For the EX Group, satellite cell count per mm2 at baseline = 9.705 (± 1.27), at 3 weeks = 10.87 (± 1.12), and at 6 weeks = 10.47 (±0.7997). For the HT Group, satellite cell count per mm2 at baseline = 8.535 (± 0.582), at 3 weeks = 11.54 (± 1.43), and at 6 weeks = 10.202 (± 0.940). Statistical analysis indicated a significant main effect of time (p=0.0125), but no significant effect of group (p=0.5504) or the group x time interaction (p=0.8412). CONCLUSION: Our findings suggest that 6 weeks of HT is insufficient to affect the satellite cell content within muscle fibers. This study provides additional insight in the literature about the effects of HT on human subjects

Developing an appropriate evolutionary baseline model for the study of SARS-CoV-2 patient samples.

Over the past 3 years, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread through human populations in several waves, resulting in a global health crisis. In response, genomic surveillance efforts have proliferated in the hopes of tracking and anticipating the evolution of this virus, resulting in millions of patient isolates now being available in public databases. Yet, while there is a tremendous focus on identifying newly emerging adaptive viral variants, this quantification is far from trivial. Specifically, multiple co-occurring and interacting evolutionary processes are constantly in operation and must be jointly considered and modeled in order to perform accurate inference. We here outline critical individual components of such an evolutionary baseline model-mutation rates, recombination rates, the distribution of fitness effects, infection dynamics, and compartmentalization-and describe the current state of knowledge pertaining to the related parameters of each in SARS-CoV-2. We close with a series of recommendations for future clinical sampling, model construction, and statistical analysis

Intercellular communication of cellular stress monitored by γ-H2AX induction

When cells are exposed to ionizing radiation (IR), unexposed cells that share media with damaged cells exhibit similar effects to irradiated cells including increased levels of DNA double-strand breaks (DSBs). Hypothesizing that this effect, known as the radiation-induced bystander effect, may be a specific instance of communication between damaged and undamaged cells regardless of damage source, we demonstrated that exposure of target cells to non-IR induces bystander damage in non-targeted cells as measured by γ-H2AX and 53BP1 focal formation. Initially, bystander damage was found primarily in S-phase cells, but at later times, non-S-phase cells were also affected. In addition, media from undamaged malignant and senescent cells also was found to induce DSBs in primary cultures. Media conditioned on cells targeted with either ionizing or non-IR as well as on undamaged malignant and senescent cells contained elevated levels of several cytokines. One of these, transforming growth factor beta (TGF-β), and nitric oxide (NO) were found to elevate numbers of γ-H2AX/53BP1 foci in normal cell cultures similar to levels found in bystander cells, and this elevation was abrogated by NO synthase inhibitors, TGF-β blocking antibody and antioxidants. These findings support the hypothesis that damage in bystander cells results from their exposure to cytokines or reactive compounds released from stressed cells, regardless of damage source. These results have implications for oncogenesis in that they indicate that damaged normal cells or undamaged tumor cells may induce genomic instability, leading to an increased risk of oncogenic transformation in other cells with which they share media or contact directly