Absolute rate constants for the cross-coupling reaction of several carbon-centered radicals with various nitroxides and their temperature dependence have been determined in liquids by kinetic absorption spectroscopy. The rate constants range from <2 x 10(5) M(-)(1) s(-)(1) to 2.3 x 10(9) M(-)(1) s(-)(1) and depend strongly on the structure of the nitroxide and the carbon-centered radical. Grossly, they decrease with increasing rate constant of the cleavage of the corresponding alkoxyamine. In many cases, the temperature dependence shows a non-Arrhenius behavior. A model assuming a short-lived intermediate that is hindered to form the coupling product by an unfavorable activation entropy leads to a satisfactory analytic description. However, the behavior is more likely due to a barrierless single-step reaction with a low exothermicity where the free energy of activation is dominated by a large negative entropy term.

Getting a look‐in: An optimized MALDI‐MS procedure has been developed to detect endogenous primary metabolites directly in the cell extract. A detection limit corresponding to metabolites from less than a single cell has been attained, opening the door to single‐cell metabolomics by mass spectrometry.

Background: Peroxisome proliferator-activated receptor ␥ coactivator 1 (PGC) ␣ and PGC-1␤ are metabolic coactivators that are dysregulated in muscle in many chronic diseases. Results: PGC-1␣ and PGC-1␤ differentially suppress expression of proinflammatory cytokines induced by various stimuli. Conclusion: In muscle cells, PGC-1␣ and PGC-1␤ modulate the NF-B pathway thus profoundly affecting inflammatory processes. Significance: Targeting PGC-1␣ and PGC-1␤ in chronic diseases might reduce inflammation and thereby reverse disease progression.

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