X-ray powder diffraction and other analyses of cellulose nanocrystals obtained from corn straw by chemical treatments.

The extraction of nanocellulose from agro-industrial wastes is feasible due to a significant amount of cellulose contained in these natural fibers. The analysis of chemical treatments effects on the fibers to obtain the nanocellulose must be taken into consideration for the definition of an adequate and efficient methodology. In this study, two alkaline treatments were used (cleaning and bleaching), as well as an acid treatment for the extraction of nanocellulose from corn straw residues. The samples were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), dynamic light scattering (DLS) and atomic force microscopy (AFM) to verify the action and modifications caused in their chemical and physical structures. It was possible to verify the extraction of hemicellulose and lignin, the reduction of fiber sizes to the nanoscale, and the final sample presenting superior crystallinity for the bleached fiber.

Characterization of cardiopulmonary function and cardiac muscarinic and adrenergic receptor density adaptation in C57BL/6 mice with chronic Trypanosoma cruzi infection.

Circulating antibodies in chagasic patients interact with myocardial beta adrenergic and muscarinic cholinergic receptors, triggering intracellular signals that alter cardiac function along the course of the disease. However, until now, experimental data in models of chronically infected chagasic mice linking the effects on myocardial beta adrenergic and muscarinic receptors to cardiopulmonary dysfunction is lacking. Thus, we studied C57BL/6 mice 8 months after intraperitoneal injection of 100 trypomastigote forms of the Colombian strain of T. cruzi. Uninfected mice, matched in age, were used as controls. Histopathological analyses (inflammation and fibrosis) and radio-ligand binding assays for estimation of muscarinic and adrenergic receptor density were performed in myocardium tissue samples. When compared to controls, infected mice had electrical conduction disturbances, diastolic dysfunction, lower O2 consumption and anaerobic threshold. In addition, hearts of chronic chagasic mice had intense inflammation and fibrosis, and decreased beta adrenergic and increased muscarinic receptor densities than normal controls. Our data suggest that chronic T. cruzi infection causes alterations in cardiac receptor density and fibrosis deposition which can be associated with cardiac conduction abnormalities, diastolic dysfunction and lower exercise capacity, associating for the first time all these functional and histopathological alterations in chagasic mice.

Kallikreins and kininogens in saliva and plasma of patients presenting with rheumatoid arthritis.

We evaluated the activities of salivary kallikrein and tissue/plasma kallikreins, and the plasma levels of high-molecular (HKg) and low-molecular (LKg) weight kininogens in patients with rheumatoid arthritis. The patients exhibited higher levels of the active salivary kallikrein compared to the controls. In contrast, the total salivary kallikrein activity of patients was not different from controls. In plasma from the patients, tissue kallikrein activity or plasma prekallikrein activity was not significantly different from the controls. Plasma HKg levels observed in patients were higher than in controls, whereas plasma LKg levels did not differ significantly from controls. Our results showed that most of the salivary kallikrein seen in patients is in its active form, suggesting the presence of systemic or local factors with the ability to activate salivary pro-kallikrein.

Kininogen-kallikrein-kinin system in plasma and saliva of patients with Sjögren's syndrome.

OBJECTIVE: To evaluate variables of the kininogen-kallikrein-kinin system (KKKS) simultaneously in plasma and saliva of patients with Sjögren's syndrome (SS). METHODS: We studied a group of 20 female patients with SS aged 37-75 years, 7 with primary SS (SS1) and 13 with SS secondary to rheumatoid arthritis (SS2), and 20 healthy individuals. Total kininogen and high and low molecular weight kininogen (HKg and LKg, respectively) levels were evaluated by ELISA. The activity of plasma and tissue kallikreins was determined by enzyme activity on selective chromogenic substrates. RESULTS: The plasma levels of total kininogen, HKg, and LKg, and the activity of plasma kallikrein observed in patients were not significantly different from controls. The tissue kallikrein-like activity in plasma and the active tissue kallikrein in saliva were significantly increased in patients with SS, whereas the total salivary tissue kallikrein activity in patients was not significantly different from controls. The concentration of protein in the saliva of patients was significantly increased, and a positive correlation between salivary protein levels and the active tissue kallikrein was observed. CONCLUSION: Comparisons between the total and the active tissue kallikrein in saliva of patients with SS showed that most of the tissue kallikrein was in its active form. In addition, we observed a concomitant increase of the tissue kallikrein-like activity in plasma. These results suggest increased activation of the KKKS in plasma and saliva of patients with SS.