3.3 Plasma syndecan-1 and tryptase concentrations increase during acute symptomatic crises
We next evaluated potential differences between plasma SD-1 and tryptase concentrations during the acute phase of CAS and those in control subjects, in order to determine whether endothelial glycocalyx shedding was activated, and whether mast cell activation might play a role in this process. During acute exacerbations, SD-1 plasma concentrations were four-fold higher (p < 0.0001) than those in control subjects, and also substantially higher than those seen in the same patients during clinically quiescent periods (p < 0.0001) (Fig. 3A) .
In view of previous evidence linking activation of mast cells with CAS (Forman et al. , 1985; Kounis et al. , 1991), we measured tryptase concentrations in plasma samples from the same patients during chronic and acute phases of CAS. There was a small but consistent increase in plasma tryptase concentrations during acute phases (n = 10; p = 0.03, Fig. 3B ).
However, plasma concentrations of MDA, an index of systemic oxidative stress, did not vary significantly between control subjects (n = 9; 3.05 ± 0.06 µM) and patients during either chronic (3.24 ± 0.15µM) or acute (3.09 ± 0.15 µM) phases of CAS (n = 9 for each phase).