Novel calcified gum Arabic porous nano-composite scaffold for bone tissue regeneration.

The aim of this study was to investigate the biomechanical and biological properties of a nanocomposite scaffold containing both mineral and polysaccharide constituents. Hydroxyapatite nanoparticles (n-HA) was synthesized from dead abra ovata shells using wet chemical methods and was used in different ratios in concert with gum Arabic, a branched plant polysaccharide. N-HA/gum nanocomposite was fabricated with freeze-drying process and characterized by FTIR and SEM for chemical structure and morphology. Porosity was estimated using liquid substitution method. The scaffold mechanical properties were evaluated by compressive test measurement. Osteogenic differentiation was assessed using alkaline phosphatase production and biomineralization was evaluated using Alizarin red assay. Results demonstrated that the hydroxyapatite/gum Arabic nanocomposite had favorable biocompatibility and a similar structure to natural bone matrix. Porous nanocomposite possessed macropore networks with a porosity 87-93% and mean pore size ranging between 164 and 230 µm. The gum/HA with a ratio of 50% w/w HA had the highest compressive modulus of ∼75.3 MPa Pa (MPa) and the ultimate compressive stress of ∼16.6 MPa. C2C12 cells cultured on a scaffold with higher percentage (40 and 50 w/w) of HA demonstrated increased ALP levels and calcium deposition. The data from the present study demonstrated significant changes to the biomechanical properties and osteoconductivity of the nanocomposite scaffold by modulating its mineral content. Nanocomposite scaffolds containing gum and n-HA of 40-50% exhibited highest mechanical properties, as well as supported increased biomineralization.

Intravitreal bevacizumab versus combined bevacizumab-triamcinolone versus macular laser photocoagulation in diabetic macular edema.

PURPOSE: To evaluate the additive effect of triamcinolone to bevacizumab in comparison to standard macular laser photocoagulation versus bevacizumab in the management of diabetic macular edema (DME). METHODS: In a prospective, randomized clinical trial, 130 eyes of 110 patients with type 2 diabetes with DME were included. Eligible eyes were randomly assigned to 1.25 mg intravitreal bevacizumab (42 eyes) (IVB group) or combination of 1.25 mg bevacizumab and 2 mg triamcinolone acetonide (41 eyes) (IVB+IVT group) or macular laser photocoagulation (47 eyes) (MPC). Central macular thickness (CMT) and visual acuity changes at week 6 and 16 were assessed. RESULTS: The mean age of the patients was 57 -/+7 years. Patients were followed 16 weeks. At week 6, all the three groups showed significant reduction in CMT but the reductions for IVB and IVB+IVT were significantly more than MPC (p<0.001). At week 16, the response was not stable for IVB (p<0.001), but IVB+IVT maintained its superior status to MPC (p<0.001). At week 16, visual acuities were essentially unchanged for the two groups of MPC and IVB and improvement for IVB+IVT was marginal and at most was 0.1 log MAR. No patient developed uveitis, endophthalmitis, or thromboembolic event. CONCLUSIONS: Single intravitreal bevacizumab or triamcinolone plus bevacizumab injection brought about significantly greater macular thickness reduction in diabetic patients in comparison to standard laser treatment. However, the response for bevacizumab alone was short-lived. Reduction in macular thickness was only marginally associated with visual acuity improvement in the triamcinolone plus bevacizumab injection group.