Development of porous chitosan-gelatin/hydroxyapatite composite scaffolds for hard tissue-engineering applications

Composite scaffolds prepared from natural polymers and hydroxyapatite (HA) are expected to have enhanced osteoconductive properties and as a result gained much attention in recent years for use in bone tissue-engineering applications. Although there are various natural polymers available for this purpose, chitosan (C) and gelatin (G) are commonly studied because of their inherent properties. The aim of this study was to prepare three-dimensional (3D) scaffolds using these two natural polymers and to add either non-sintered hydroxyapatite (nsHA) or sintered hydroxyapatite (sHA) to compare their influence on physical, chemical and mechanical properties of the scaffolds and on their affinities towards Saos-2 cells. For this purpose, nsHA and sHA were synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and particle size analyses. Then nsHA and sHA particles, with average sizes of 16 mu m and 6 mu m, respectively, were added to the solutions of C and G during the preparation step and the resultant 3D scaffolds were characterized. Compression tests indicated that presence of nsHA or sHA increased the Young's modulus and compressive strength of the scaffolds, and the values were very similar to those of human spongy bone. MTS assays, confocal microscopy and SEM analysis showed that cell attachment and proliferation were higher on C?G/sHA composite scaffolds compared to the other scaffolds. It was shown that the scaffolds prepared from chitosan, gelatin and HA are appropriate cell carriers for bone tissue engineering, especially those with sHA incorporated. Copyright (C) 2011 John Wiley & Sons, Ltd

Radiotherapy for stage I seminoma of the testis

Background : After orchiectomy in stage I seminoma the standard is adjuvant radiation therapy. We analyzed the patients retrospectively to evaluate the contributions of the treatment volume and dosage to treatment outcomes. Materials and Methods : Between January 1999 and December 2005, 91 stage I seminoma patients with a median age 36 (range;22-62) applied to our center, who were treated using anterior-posterior parallel opposed fields with linear accelerator or Co60 after orchiectomy. Twenty-five (27.5%) patients received irradiation to the paraaortic and ipsilateral pelvic nodes, and 66 (62.5%) patients only received to paraaortic nodes. Results : With a follow up time of median 57 months (range; 27-104), paraaortic nodes treated group had 4 relapses (6%) - 3 of them pelvic, one of them both pelvic and paraaortic. Both paraaortic and ipsilateral nodes irradiated patients had only one relapse (4%) (P = 0.726). While the 5 year overall survival (OS) is 98.8%, it is 100% in the dog-leg group and 98.4% in the paraaortic group (P = 0.548). Univariate analyses of OS and Disease Free Survival (DFS) showed that there is no statistically significant difference related to factors as age, histologic subgroup, tumor size, rete testis involvement, radiotherapy (RT) fields, dose ranges and the therapy device. Conclusion : Adjuvant RT approach is the preferred for non-compliant low risk patients as well as intermediate and high risk patient in stage I seminoma. 20 Gy/ 10 fractions/ 2 weeks RT is the adequate treatment

Brain regions associated with the risk and resilience for bipolar I disorder: a voxel based MRI study

25th Congress of the European-College-of-Neuropsychopharmacology (ECNP) -- OCT 13-17, 2012 -- Vienna, AUSTRIAWOS: 000317948600184European Coll Neuropsychopharmacol (ECNP

A cell attracting composite of lumbar fusion cage

Lumbar fusion cages are devices used in spinal fusion procedures for disorders such as spondylosis and degenerative disc diseases that may occur due to age, trauma or genetic reasons. These devices are most frequently made of metals and polymers. The mechanical properties of such devices should be comparable to the bone to avoid stress shielding. Besides, cages should interact with the cells to prevent extrusion and achieve satisfactory fusion. In this study, poly(methylmethacrylate) (PMMA) and hydroxyapatite (HAp) were compounded to create products with HAp contents up to 40% (w/w), processed by hot melt extrusion and injection molded to produce composites with maximum polymer-mineral interaction. The morphology, interaction with the plates and rate of proliferation of human osteoblast-like (HOB) cells were studied in vitro. We learned that cells interact more with HAp when the HAp content is higher than 20%. Tensile and compressive properties of PMMA were significantly increased with increasing HAp content; from an elastic modulus (E) of 2.08 to 3.92GPa in tension, and from 349 to 562MPa in compression. High HAp content of the samples increased the roughness from 0.69m for pure PMMA to 1.35m for 40% (w/w) HAp loaded PMMA, increased cell proliferation and as a result the cells presented filopodia indicating a satisfactory level of interaction with the cage surface. Based on mechanical and in vitro studies, a HAp content of around 30% (w/w) was found to be appropriate for good cell adhesion and satisfactory mechanical properties for use in the construction of a fusion cage. It was concluded that when PMMA and HAp were compounded at an optimal value, a cage material with adequate mechanical properties and increased cell attachment can be obtained for use in spinal fusion applications