Evaluation of Chitosan-Based Films Containing Gelatin, Chondroitin 4-Sulfate and ZnO for Wound Healing.

In this work, chitosan-based films containing gelatin and chondroitin-4-sulfate (C4S) with and without ZnO particles were produced and tested in vitro to investigate their potential wound healing properties. Chitosans were produced from shrimp-head processing waste by alkaline deacetylation of chitin to obtain chitosans differing in molecular weight and degree of deacetylation (80 ± 0.5%). The film-forming solutions (chitosan, C4S and gelatin) and ZnO suspension showed no toxicity towards fibroblasts or keratinocytes. Chitosan was able to agglutinate red blood cells, and film-forming solutions induced no hemolysis. Film components were released into solution when incubated in PBS as demonstrated by protein and sugar determination. These data suggest that a stable, chitosan-based film with low toxicity and an ability to release components would be able to establish a biocompatible microenvironment for cell growth. Chitosan-based films significantly increased the percentage of wound healing (wound contraction from 65 to 86%) in skin with full-thickness excision when compared with control (51%), after 6 days. Moreover, histological analysis showed increased granulation tissue in chitosan and chitosan/gelatin/C4S/ZnO films. Chitosan-based biopolymer composites could be used for improved biomedical applications such as wound dressings, giving them enhanced properties.

Differential vulnerability of substantia nigra and corpus striatum to oxidative insult induced by reduced dietary levels of essential fatty acids.

Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.

Purification and partial characterisation of a trypsin from the processing waste of the silver mojarra (Diapterus rhombeus).

An alkaline peptidase was purified from the viscera of the silver mojarra (Diapterus rhombeus) in a three-step process: heat treatment, ammonium sulphate fractionation and molecular exclusion chromatography (Sephadex® G-75), with final specific activity 86-fold higher than the enzyme extract and yield of 22.1%. The purified enzyme had an estimated molecular mass of 26.5kDa and NH2-terminal amino acid sequence IVGGYECTMHSEAHE. Higher enzyme activity was observed at pH 8.5 and between 50 and 55°C. The enzyme was completely inactivated after 30min at 55°C and it was significantly more stable at alkaline pH. Km, Kcat and Kcat·Km(-1) values, using BApNA as substrate, were 0.266mM, 0.93s(-1) and 3.48mM(-1)s(-1), respectively. Enzyme activity increased in the presence of the ions (1mM) K(+), Li(+) and Ca(2+), but was inhibited by Fe(2+), Cd(2+), Cu(2+), Al(3+), Hg(2+), Zn(2+) and Pb(2+) as well as by the trypsin inhibitors TLCK and benzamidine.