Rheological Study of Genipin Cross-Linked Chitosan Hydrogels

This paper reports the rheological behavior of chitosan solutions that have been cross-linked with different amounts of genipin, at body temperature and physiological pH. The effect of the cross-linker loading on the rheological properties of hydrogels has been evaluated. The oscillatory time sweep method was used to monitor the dynamic viscoelastic parameters during in situ (i.e., in the rheometer) gelation experiments, enabling the determination of the gelation time. The stress and frequency sweeps were employed to measure G′ of the cured hydrogels. It was found that the solutions of chitosan cross-linked with genipin, under physiological conditions, could form relatively strong elastic gels when compared to those of pure chitosan. Moreover, the gelation time obtained from the crossover of G′′ and G′ was in excellent agreement with the value obtained from the Winter–Chambon criterion. A significant reduction on this parameter was achieved even at low genipin concentrations. This behavior suggests that these formulations are able to be produced in situ and thus constitute promising matrices for cells and bioactive molecule encapsulations

The burden and measurement of cardiovascular disease in SSc

The prognosis for patients with systemic sclerosis (SSc) has improved in the past three decades, with fewer patients succumbing to renal-crisis-related death. While pulmonary fibrosis and hypertension are currently the most frequent causes of death, there is evidence that cardiovascular disease will have an important role in the long-term prognosis of SSc in the future. Ischemia-reperfusion injury and endothelial dysfunction are cardinal features of SSc, and may predispose a patient to microvascular disease and atherosclerosis. In order to alleviate the cardiovascular burden in patients with SSc, it is important to detect endothelial dysfunction, microvascular flow disturbance and atherosclerosis. Noninvasive techniques that evaluate flow-mediated dilatation and arterial pulse waves (endothelial function measurements), microvascular blood flow (measurement of the microcirculation), carotid intima-media thickness and left ventricular hypertrophy (detection of atherosclerosis) are recommended. In addition, these measurements will facilitate trials of therapeutic strategies that, in addition to controlling conventional risk factors, prevent and treat cardiovascular disease in patients with SSc. © 2010 Macmillan Publishers Limited. All rights reserved.link_to_subscribed_fulltex