A physiological drop in pH decreases mitochondrial respiration, and HDAC and Akt signaling, in L6 myocytes

Exercise stimulates mitochondrial biogenesis and increases mitochondrial respiratory function and content. However, during high-intensity exercise muscle pH can decrease below pH 6.8 with a concomitant increase in lactate concentration. This drop in muscle pH is associated with reduced exercise-induced mitochondrial biogenesis, while increased lactate may act as a signaling molecule to affect mitochondrial biogenesis. Therefore, in this study we wished to determine the impact of altering pH and lactate concentration in L6 myotubes on genes and proteins known to be involved in mitochondrial biogenesis. We also examined mitochondrial respiration in response to these perturbations. Differentiated L6 myotubes were exposed to normal (pH 7.5)-, low (pH 7.0)-, or high (pH 8.0)-pH media with and without 20 mM sodium l-lactate for 1 and 6 h. Low pH and 20 mM sodium l-lactate resulted in decreased Akt (Ser473) and AMPK (T172) phosphorylation at 1 h compared with controls, while at 6 h the nuclear localization of histone deacetylase 5 (HDAC5) was decreased. When the pH was increased both Akt (Ser473) and AMPK (T172) phosphorylation was increased at 1 h. Overall increased lactate decreased the nuclear content of HDAC5 at 6 h. Exposure to both high- and low-pH media decreased basal mitochondrial respiration, ATP turnover, and maximum mitochondrial respiratory capacity. These data indicate that muscle pH affects several metabolic signaling pathways, including those required for mitochondrial function

Mitochondrial dysfunction has divergent, cell type-dependent effects on insulin action

The contribution of mitochondrial dysfunction to insulin resistance is a contentious issue in metabolic research. Recent evidence implicates mitochondrial dysfunction as contributing to multiple forms of insulin resistance. However, some models of mitochondrial dysfunction fail to induce insulin resistance, suggesting greater complexity describes mitochondrial regulation of insulin action. We report that mitochondrial dysfunction is not necessary for cellular models of insulin resistance. However, impairment of mitochondrial function is sufficient for insulin resistance in a cell type-dependent manner, with impaired mitochondrial function inducing insulin resistance in adipocytes, but having no effect, or insulin sensitising effects in hepatocytes. The mechanism of mitochondrial impairment was important in determining the impact on insulin action, but was independent of mitochondrial ROS production. These data can account for opposing findings on this issue and highlight the complexity of mitochondrial regulation of cell type-specific insulin action, which is not described by current reductionist paradigms

Determination of intracellular glutathione and glutathione disulfide using high performance liquid chromatography with acidic potassium permanganate chemiluminescence detection

Measurement of glutathione (GSH) and glutathione disulfide (GSSG) is a crucial tool to assess cellular redox state. Herein we report a direct approach to determine intracellular GSH based on a rapid chromatographic separation coupled with acidic potassium permanganate chemiluminescence detection, which was extended to GSSG by incorporating thiol blocking and disulfide bond reduction. Importantly, this simple procedure avoids derivatisation of GSH (thus minimising auto-oxidation) and overcomes problems encountered when deriving the concentration of GSSG from &lsquo;total GSH&rsquo;. The linear range and limit of detection for both analytes were 7.5 &times; 10&minus;7 to 1 &times; 10&minus;5 M, and 5 &times; 10&minus;7 M, respectively. GSH and GSSG were determined in cultured muscle cells treated for 24 h with glucose oxidase (0, 15, 30, 100, 250 and 500 mU mL&minus;1), which exposed them to a continuous source of reactive oxygen species (ROS). Both analyte concentrations were greater in myotubes treated with 100 or 250 mU mL&minus;1 glucose oxidase (compared to untreated controls), but were significantly lower in myotubes treated with 500 mU mL&minus;1 (p &lt; 0.05), which was rationalised by considering measurements of H2O2 and cell viability. However, the GSH/GSSG ratio in myotubes treated with 100, 250 and 500 mU mL&minus;1 glucose oxidase exhibited a dose-dependent decrease that reflected the increase in intracellular ROS.<br /

The use of group dynamics strategies to enhance cohesion in a lifestyle intervention program for obese children

<p>Abstract</p> <p>Background</p> <p>Most research pertaining to childhood obesity has assessed the effectiveness of preventative interventions, while relatively little has been done to advance knowledge in the treatment of obesity. Thus, a 4-week family- and group-based intervention utilizing group dynamics strategies designed to increase cohesion was implemented to influence the lifestyles and physical activity levels of obese children.</p> <p>Methods/Design</p> <p>This paper provides an overview of the rationale for and implementation of the intervention for obese children and their families. Objectives of the intervention included the modification of health behaviors and cohesion levels through the use of group dynamics strategies. To date, a total of 15 children (7 boys and 8 girls, mean age = 10.5) and their families have completed the intervention (during the month of August 2008). Physiological and psychological outcomes were assessed throughout the 4-week intervention and at 3-, 6-, and 12-month follow-up periods.</p> <p>Discussion</p> <p>It is believed that the information provided will help researchers and health professionals develop similar obesity treatment interventions through the use of evidence-based group dynamics strategies. There is also a need for continued research in this area, and it is our hope that the Children's Health and Activity Modification Program (C.H.A.M.P.) will provide a strong base from which others may build.</p

Athlete health protection: Why qualitative research matters

Qualitative research is increasingly recognised as relevant and useful to uncovering and understanding new and differentiated insights that move both research and practice forward. The field of athlete health protection – that is, injury and illness prevention and management – is reliant on high-quality knowledge of athlete and other key stakeholders’ perspectives, understanding of the complex relations within the athlete health protection system, the socio-ecological context in which athletes are provided with prevention and care, and how best to influence those involved in athlete health protection for better and more effective outcomes. Yet, deep interrogation of these aspects is often overlooked in favour of quantitatively-driven research questions. As athlete health protection research and practice matures, we argue that there is a need for research that complements traditional approaches, connects researchers 3 from different disciplines - but which also distinctly holds space for the unique insights that qualitative approaches can add. The purpose of this editorial is to highlight the importance, value, and relevance of qualitative research to the field of athlete health protection – in other words, why qualitative research matters

Triggering the first Amendment: Newsgathering torts and press freedom

The recent Food Lion case highlights attempts by those suing the press to short-circuit First Amendment protections by attacking how news is gathered rather than its publication. This article examines recent cases illustrative of this trend, which may have been accelerated by unfortunate statements in a 1991 United States Supreme Court case, Cohen v. Cowles Media Co. Next, the article analyzes and critiques the current state of the law, with particular attention to the somewhat ambiguous issue of when First Amendment scrutiny is triggered. Finally, the article suggests a new analytical framework that provides heightened protection for the press as it goes about the vital process of gathering new