Alterations of the arginine metabolome in asthma.

Rationale: As the sole nitrogen donor in nitric oxide (NO) synthesis and key intermediate in the urea cycle, arginine and its metabolic pathways are integrally linked to cellular respiration, metabolism, and inflammation.

Objectives: We hypothesized that arginine (Arg) bioavailability would be associated with airflow abnormalities and inflammation in subjects with asthma, and would be informative for asthma severity.

Methods: Arg bioavailability was assessed in subjects with severe and nonsevere asthma and healthy control subjects by determination of plasma Arg relative to its metabolic products, ornithine and citrulline, and relative to methylarginine inhibitors of NO synthases, and by serum arginase activity.

Signal transduction and oxidative processes in sinonasal polyposis.

Background: Nasal polyposis is characterized by impaired regulation of nasal tissue growth and is associated with chronic inflammation, sinus infections, and low levels of nitric oxide (NO). Based on its critical role in mediating cell growth and antimicrobial function, decrease of NO levels has been implicated in the pathogenesis of nasal polyposis.

Objective: We sought to evaluate mechanisms for the low NO level in polyposis, including factors regulating NO synthase (NOS) expression and activity and NO consumptive processes in nasal epithelial cells and nasal lavage fluid.