Non-invasive assessment of healing of bacteria infected and uninfected wounds using optical coherence tomography.

BACKGROUND/PURPOSE: Bacterial infection is one of the main predisposing factors for the delay in wound healing. To facilitate a timely decision for correct therapy, it is important to accurately monitor the morphological changes in the infected wounds using noninvasive tools. In the present study, we have explored the use of optical coherence tomography (OCT) for monitoring the healing of superficial wounds infected with Staphylococcus aureus in mice under in vitro and in vivo conditions and studied the changes in collagen birefringence in the infected wounds. METHODS: The tape stripping method was used for generating superficial skin wounds in mice and wounds were infected with S. aureus. For in vitro studies, infected and uninfected wound tissues were resected, back scattered intensity and birefringence changes in collagen during wound healing were studied on the 2, 4 and 10th day of postinfection using polarization-sensitive (PS) OCT and images were compared with histology. Real-time OCT was used for studying the kinetics of healing of infected wounds under in vivo conditions. RESULTS: From the PS-OCT images, different phases of wound healing such as inflammation, reepithelialization and collagen remodeling could be identified. The edematic regions appeared prominent in infected wounds. Compared with uninfected wounds, reepithelization and collagen remodeling phases of wound healing were delayed significantly in the infected wounds. These changes were comparable with the different stages of wound healing observed under in vivo conditions. CONCLUSION: OCT imaging can provide a rapid assessment of the morphological changes associated with bacteria-infected and uninfected wounds and thereby aid in timely treatment planning.

Acute toxicity assessment of textile dyes and textile and dye industrial effluents using Daphnia magna bioassay.

Aquatic toxicity of textile dyes and textile and dye industrial effluents were evaluated in an acute toxicity study using Daphnia magna as an aquatic experimental animal model. The 48-h EC(50) value for the azo dyes, Remazol Parrot Green was 55.32 mg/L and for Remazol Golden Yellow was 46.84 mg/L. Whereas 48-h EC(50) values for three dye industrial effluents (D1, D2, and D3) were 14.12%, 15.52%, and 29.69%, respectively. Similarly, EC(50) value for three textile mill effluents (T1, T2, and T3) were >100%, 62.97%, and 63.04%, respectively. These results also showed linear relationship with high degree of confidence (r(2)A =A >0.84 to >0.99) between immobility and test concentrations. The ratio of 24 to 48-h EC(50) remains to be in between 1.1 and 1.2. The general criteria of toxicity classification showed that both dyes were minor acutely toxic having 48-h EC(50) in between 10 and 100 mg/L. Of the six textile and dye industrial effluents tested, one was not acutely toxic (48-h EC(50)A >A 100%) and five were minor acutely toxic (48-h EC(50)A >A 14.12-29.69%). The toxicity classification of effluent based on toxic unit (TU) showed that of the six effluents tested five were found toxic (TU = >1) and one was non-toxic (TU = <1). Thus, dye effluents showed highest toxicity and textile effluents lowest toxicity. The study also suggested that the assay with D.A magna was an excellent method for evaluation of aquatic toxicity of dyes and dyes containing industrial effluents.