The surface chemistry of Eucalyptus grandis wood pulp fibres was investigated using the sessile
drop apparent contact angle, XPS and TOF-SIMS techniques. Pulp fibres were studied using different
chemical pulping conditions. The pulping affected the surface coverage of lignin and extractives,
as indicated by XPS, and the work of adhesion with water, as estimated from contact angle
determinations. The amount of surface lignin decreased while surface extractives and work of adhesion
with water increased in relation to the amount of active alkali used in the pulping. Desorption
and analysis of surface extractives by TOF-SIMS showed sterols, fatty acid calcium and sodium
salts. After acetone extraction the spectra obtained by TOF-SIMS showed changes. However, calcium
and sodium salts of fatty acids were still detected, indicating their resistance to solvent extraction.
This resistance to extraction can affect the lignin and extractive surface coverage estimations
using XPS due to the contribution of the carbon content after extraction. The extent of
interference was, however, uncertain.
Gnathostomiasis is a prevalent zoonosis in humans in some regions of the world. The genus Gnathostoma is considered an accidental parasite for humans; G. binucleatum is the endemic species in Nayarit, Mexico. This work was designed to determine the proteolytic activity of the excretory-secretory products (ESP) of advanced third-stage larvae (ADVL3) of Gnathostoma binucleatum against human fibronectin and antibodies from human and sheep. Our findings showed protease activity against human fibronectin as well as sheep and human gamma globulins of the ESP at molecular weights of 80 and 56 kDa. The proteases found in the ESP of G. binucleatum are thus candidate molecules for consideration as pathogenic elements, owing to the fact that they destroy proteins of the host tissue, which probably allows them to migrate through those tissues and degrade molecules involved in the humoral immune response.
Gnathostomiasis is an emerging infectious disease, in which the agent Gnathostoma binucleatum is the only species known to infect humans in Mexico. Although the humoral immune response to G. binucleatum has been analyzed previously, here we evaluated the lymphoproliferative response of peripheral blood lymphocytic cells from patients clinically diagnosed with gnathostomiasis against a crude extract of G. binucleatum using the MTT method, and compared the response to that of healthy subjects. No differences in the response to concanavalin A were found between the groups; however, the response to the crude extract was statistically higher in patients compared to healthy controls (1.188 ± 0.135, and 1.000 ± 0.045, p = 0.0004). Patients at > 6 months after diagnosis showed a higher lymphoproliferative response than the group of healthy subjects, and those at < 6 months after diagnosis (p = 0.0001, and 0.0164 respectively). These data suggest that the parasite induces non-protective immunological memory.