SIRT1 and chronic obstructive pulmonary disease: Rajendrasozhan et al. for the first time demonstrated that Sirt1 is decreased in lungs of smokers and COPD patients and that such reduced levels were inversely correlated to increased posttranslational modifications of the protein by increasing amount of reactive aldehyde 4-hydroxy-2-nonenol and 3-nitrotyrosine, markers of oxidative and nitrosative stress, respectively.