Optimizing training adaptations by manipulating glycogen

For decades, glycogen has been recognized as a storage form of glucose within the liver and muscles. Only recently has a greater role for glycogen as a regulator of metabolic signalling been suggested. Glycogen either directly or indirectly regulates a number of signalling proteins, including the adenosine-5\u27-phosphate- (AMP-) activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (MAPK). AMPK and p38 MAPK play a significant role in controlling the expression and activity of the peroxisome proliferator activated receptor &gamma; coactivators (PGCs), respectively. The PGCs can directly increase muscle mitochondrial mass and endurance exercise performance. As low muscle glycogen is generally associated with greater activation of these pathways, the concept of training with low glycogen to maximize the physiological adaptations to endurance exercise is gaining acceptance in the scientific community. In this review, we evaluate the scientific basis for this philosophy and propose some practical applications of this philosophy for the general population as well as elite endurance athletes.<br /

Effects of intranasal TNFα on granulocyte recruitment and activity in healthy subjects and patients with allergic rhinitis

<p>Abstract</p> <p>Background</p> <p>TNFα may contribute to the pathophysiology of airway inflammation. For example, we have recently shown that nasal administration of TNFα produces late phase co-appearance of granulocyte and plasma exudation markers on the mucosal surface. The objective of the present study was to examine indices of granulocyte presence and activity in response to intranasal TNFα challenge.</p> <p>Methods</p> <p>Healthy subjects and patients with allergic rhinitis (examined out of season) were subjected to nasal challenge with TNFα (10 μg) in a sham-controlled and crossover design. Nasal lavages were carried out prior to and 24 hours post challenge. Nasal biopsies were obtained post challenge. Nasal lavage fluid levels of myeloperoxidase (MPO) and eosinophil cationic protein (ECP) were analyzed as indices of neutrophil and eosinophil activity. Moreover, IL-8 and α₂-macroglobulin were analyzed as markers of pro-inflammatory cytokine production and plasma exudation. Nasal biopsy numbers of neutrophils and eosinophils were monitored.</p> <p>Results</p> <p>Nasal lavage fluid levels of MPO recorded 24 hours post TNFα challenge were increased in healthy subjects (p = 0.0081) and in patients with allergic rhinitis (p = 0.0081) (<it>c.f</it>. sham challenge). Similarly, α₂-macroglobulin was increased in healthy subjects (p = 0.014) and in patients with allergic rhinitis (p = 0.0034). Lavage fluid levels of ECP and IL-8 were not affected by TNFα challenge. TNFα increased the numbers of subepithelial neutrophils (p = 0.0021), but not the numbers of eosinophils.</p> <p>Conclusion</p> <p>TNFα produces a nasal inflammatory response in humans that is characterised by late phase (i.e., 24 hours post challenge) neutrophil activity and plasma exudation.</p

Hydrogen-transfer catalysis with Cp*Ir^III complexes:The influence of the ancillary ligands

Fourteen Cp*IrIII complexes, bearing various combinations of N- and C-spectator ligands, are assayed in hydrogen-transfer catalysis from isopropyl alcohol to acetophenone under various conditions to investigate ligand effects in this widely used reaction. The new cationic complexes bearing monodentate pyridine and N-heterocyclic carbene (NHC) ligands were characterized crystallographically and by variable-temperature nuclear magnetic resonance (VT-NMR). Control experiments and mercury poisoning tests showed that iridium(0) nanoparticles, although active in the reaction, are not responsible for the high activity observed for the most active precatalyst [Cp*Ir(IMe) 2Cl]BF4 (6). For efficient catalysis, it was found necessary to have both NHCs in monodentate form; tying them together in a bis-NHC chelate ligand gave greatly reduced activity. The kinetics of the base-assisted reaction showed induction periods as well as deactivation processes, and H/D scrambling experiments cast some doubt on the classical monohydride mechanism. © 2013 American Chemical Society

Exercise-induced protein kinase C isoform-specific activation in human skeletal muscle

We determined whether protein kinase C (PKC) isoforms are redistributed and phosphorylated in response to acute exercise in skeletal muscle. Muscle biopsies were obtained from six healthy subjects (four women, two men; age 25 +/- 1 years) before, during, and after 60 min of one-leg cycle ergometry at approximately 70% VO(2peak). Exercise for 30 and 60 min was associated with a three- and fourfold increase in PKC-zeta/lambda abundance and a four- and threefold increase in phosphorylation, respectively, in total membranes (P < 0.05) and a decrease in PKC-zeta/lambda phosphorylation in cytosolic fractions. During exercise recovery, PKC-zeta/lambda abundance and phosphorylation remained elevated. PKC-zeta/lambda abundance and phosphorylation were increased in nonexercised muscle upon cessation of exercise, indicating a systemic response may contribute to changes in PKC abundance and phosphorylation. Exercise did not change PKC-delta or -epsilon abundance or phosphorylation in either the cytosolic or total membrane fraction. In conclusion, exercise is associated with an isoform-specific effect on PKC. PKC-zeta/lambda are candidate PKC isoforms that may play a role in the regulation of exercise-related changes in metabolic and gene-regulatory responses