The fibrinogen cleavage product Aα-Val360, a specific marker of neutrophil elastase activity in vivo.

BACKGROUND: Alpha-1-antitrypsin (A1AT) deficiency is the only recognised genetic risk factor for chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide. Since A1AT is the major inhibitor of neutrophil elastase (NE), this enzyme has become widely implicated in the pathogenesis of COPD in general; however, there is currently no specific biomarker for its pre-inhibition activity. Such a biomarker should be a measure of elastase-specific COPD disease activity with the potential to assess early targeted therapeutic intervention, in contrast to traditional and non-specific disease severity markers such as forced expiratory volume in 1 s. METHODS: In pilot studies, plasma Aα-Val(360) and markers of neutrophil activation were measured in 95 subjects with a range of A1AT concentrations. Aα-Val(360) and sputum elastase activity were also measured in a further seven PiZ A1AT-deficient subjects over the course of an acute exacerbation. Finally, Aα-Val(360) was measured in plasma from subjects randomised to receive A1AT replacement or placebo in the EXACTLE trial. RESULTS: The plasma concentrations of Aα-Val(360) and A1AT related exponentially, consistent with previous theoretical and in vitro experimental data. L-233 (an intracellular NE inhibitor) blocked generation of Aα-Val(360) and subsequent A1AT/NE complex formation. Aα-Val(360) was related to the spirometric severity of lung disease in A1AT deficiency, to sputum elastase activity in acute exacerbations and was decreased in subjects receiving A1AT replacement therapy (while remaining constant in those receiving placebo). CONCLUSIONS: Aα-Val(360) represents the first specific footprint of pre-inhibition NE activity and is a potential biomarker of disease activity and progression in subjects with elastase-dependent COPD. TRIAL REGISTRATION: The EXACTLE study was registered in ClinicalTrials.gov as 'Antitrypsin (AAT) to Treat Emphysema in AAT-Deficient Patients'; ClinicalTrials.gov Identifier: NCT00263887.

Bicyclic amidine inhibitors of nitric oxide synthase: discovery of perhydro-iminopyrindine and perhydro-iminoquinoline as potent, orally active inhibitors of inducible nitric oxide synthase.

Syntheses and nitric oxide synthase inhibitory activity of cyclic amidines containing 5,6- 6,6- and 7,6-fused systems are described. X-ray structure determination facilitated the assignment of the stereochemistry of the most active compounds perhydro-2-iminoisoquinoline (8a) and perhydro-2-iminopyrindine (10a). Both 8a and 10a are very potent inhibitors of iNOS, with excellent selectivity over eNOS and they are orally active in rats with long duration suitable for once or twice a day dosing.

Synthesis of analogs of (1,4)-3- and 5-imino oxazepane, thiazepane, and diazepane as inhibitors of nitric oxide synthases.

A series of 3- and 5-imino analogs from oxazepane, thiazepane, and diazepane was prepared and evaluated as inhibitors of human nitric oxide synthesis (NOS). The most potent iNOS inhibitor was the thiazepane analog 25 (IC(50) = 0.19 microM).

Evaluation of pyrrolidin-2-imines and 1,3-thiazolidin-2-imines as inhibitors of nitric oxide synthase.

Syntheses and evaluation of pyrrolidin-2-imines and 1,3-thiazolidin-2-imines as inhibitors of nitric oxide synthase (NOS) are discussed. An extensive SAR was established for pyrrolidin-2-imines class of compounds. The amidines came out as the most potent inhibitors in addition to displaying selectivity.