ABSTRACT
Chitosan/PVA hydrogel films crosslinked by the freeze-thaw method and containing honey and allantoin were prepared for application as wound dressing materials. The effects of the freeze-thaw process and the addition of honey and allantoin on the swelling, the gel content and the mechanical properties of the samples were evaluated. The physicochemical properties of the samples, with and without the freeze-thaw process, were compared using FTIR, DSC and XRD. The results showed that the freeze-thaw process can increase the crystallinity and thermal stability of chitosan/PVA films. The freeze-thaw process increased the gel content but did not have a significant effect on the tensile strength. The presence of honey reduced the swelling and the tensile strength of the hydrogels due to hydrogen bonding interactions with PVA and chitosan chains. Long-term cell culture experiments using normal human dermal fibroblast (NHDF) cells showed that the hydrogels maintained their biocompatibility, and the cells showed extended morphology on the surface of the hydrogels for more than 30 days. The presence of honey significantly increased the biocompatibility of the hydrogels. The release of allantoin from the hydrogel was studied and, according to the Korsmeyer-Peppas and Weibull models, the mechanism was mainly diffusional. The results for the antimicrobial activity against E. coli and S. aureus bacteria showed that the allantoin-containing samples had a more remarkable antibacterial activity against S. aureus. According to the wound healing experiments, 98% of the wound area treated by the chitosan/PVA/honey hydrogel was closed, compared to 89% for the control. The results of this study suggest that the freeze-thaw process is a non-toxic crosslinking method for the preparation of chitosan/PVA hydrogels with long term biocompatibility that can be applied for wound healing and skin tissue engineering.
ABSTRACT
OBJECTIVE: Crimean-Congo hemorrhagic fever (CCHF) is an acute viral disease. Several factors have already been suggested to explain the pathogenesis as well as predict the disease severity. In our study we aim to investigate the role of serum ferritin level as a possible predicting factor of disease severity in these patients. MATERIALS AND METHODS: We evaluated all patients with laboratory confirmed diagnosis of CCHF who were admitted to Boo-Ali Hospital of Zahedan from May 2011 to June 2012. Confirmation of the disease determined using the presence of anti- CCHFV IgM in the serum by enzyme-linked immunosorbent assay (ELISA) or by polymerase chain reaction(PCR). After ethical approval, patients were categorized into two groups of mild and severe disease according to disseminated intravascular coagulation (DIC) severity using the scoring system of International Society on Thrombosis and Hemostasis (ISTH). Serum ferritin levels were evaluated and compared between these two groups. Receiver operating characteristic (ROC) curve analysis was performed to assess the optimal cutoff value of serum ferritin for predicting the disease severity. RESULTS: A total of 42 patients (36 men, 6 women, age range: 17-78 years) were included in this study, of whom 38% had Persian and 62% had Baloch ethnicity. According to DIC severity score, 54.7% of the patients had severe disease and 45.3% had mild disease. The area under the ROC curve was 0.896 and 95% CI was 0.801-0.991 (p<0.0001). A cut-off point of 1060 ng/dL, had a sensitivity of 78.9%, a specificity of 87%, a positive predictive value of 6% and a negative predictive value of 100%. Positive and negative likelihood ratios for this serum ferritin level were 6.05 and 0.24, respectively. CONCLUSION: Increased serum ferritin level has a significant positive correlation with disease severity in patients with CCHF and can evaluate the prognosis of these patients with a high sensitivity and specificity.
