Enhanced Stability of Calcium Sulfate Scaffolds with 45S5 Bioglass for Bone Repair

Calcium sulfate (CaSO₄), as a promising tissue repair material, has been applied widely due to its outstanding bioabsorbability and osteoconduction. However, fast disintegration, insufficient mechanical strength and poor bioactivity have limited its further application. In the study, CaSO₄ scaffolds fabricated by using selective laser sintering were improved by adding 45S5 bioglass. The 45S5 bioglass enhanced stability significantly due to the bond effect of glassy phase between the CaSO₄ grains. After immersing for four days in simulated body fluid (SBF), the specimens with 45S5 bioglass could still retain its original shape compared as opposed to specimens without 45S5 bioglass who experienced disintegration. Meanwhile, its compressive strength and fracture toughness increased by 80% and 37%, respectively. Furthermore, the apatite layer was formed on the CaSO₄ scaffolds with 45S5 bioglass in SBF, indicating good bioactivity of the scaffolds. In addition, the scaffolds showed good ability to support the osteoblast-like cell adhesion and proliferation.     

The circulating insulin‐like growth factor system in children with coeliac disease: an additional marker for disease activity

Background

Chronic undernutrition resulting from coeliac disease (CD) could be associated with changes in the circulating insulin‐like growth factor (IGF) system, which may participate in the pathogenesis of growth retardation occurring in these patients.

Methods

We performed a cross‐sectional study in CD subjects attempting to (1) document the pattern of serum IGF‐I and IGF binding protein (IGFBP) 1 and 3 at diagnosis and (2) assess the response of circulating IGF system to dietary treatments, in comparison with the response of clinical and laboratory findings utilized for the diagnosis of CD. Thirty‐two prepubertal CD children were divided into three groups based on the dietetic treatment: at diagnosis (D, n=18); on gluten‐free diet for at least 6 months (GFD, n=7); and on gluten challenge for at least 3 months (CH, n=7). Six postpubertal CD patients were also studied at diagnosis.

Results

In prepubertal children IGF‐I levels were significantly reduced (by 29%) in D vs sex‐ and age‐matched normal control (NC) subjects, with reductions being more pronounced before 3 years of age. Likewise, serum IGFBP‐3 concentrations were decreased by 22%, whereas circulating IGFBP‐1 levels were increased by 60%, compared with NC, with more marked IGFBP changes in older children. Similar alterations were observed in postpubertal patients. Changes in the circulating IGF system disappeared in GFD subjects and reappeared in CH children, as positivity of disease‐specific antibodies. Body mass index (BMI) also improved in GFD subjects, but did not decrease in CH children. Changes in IGF‐I and IGFBPs did not correlate with each other. Levels of IGF‐I, but not of IGFBPs, maintained the relation with age and correlated significantly with BMI and positivity of antibodies.

Conclusions

These results demonstrate that CD patients show significant changes in serum IGF‐I, in younger children, and IGFBPs (particularly IGFBP‐1), in older children and adolescents, correlating with clinical course and response to dietary treatments. The alteration in the circulating IGF system could be implicated in the pathogenesis of growth retardation occurring in CD and may provide an additional tool in monitoring of the disease. Copyright © 1999 John Wiley & Sons, Ltd.

     

The State of Starch/Hydroxyapatite Composite Scaffold in Bone Tissue Engineering with Consideration for Dielectric Measurement as an Alternative Characterization Technique

Hydroxyapatite (HA) has been widely used as a scaffold in tissue engineering. HA possesses high mechanical stress and exhibits particularly excellent biocompatibility owing to its similarity to natural bone. Nonetheless, this ceramic scaffold has limited applications due to its apparent brittleness. Therefore, this had presented some difficulties when shaping implants out of HA and for sustaining a high mechanical load. Fortunately, these drawbacks can be improved by combining HA with other biomaterials. Starch was heavily considered for biomedical device applications in favor of its low cost, wide availability, and biocompatibility properties that complement HA. This review provides an insight into starch/HA composites used in the fabrication of bone tissue scaffolds and numerous factors that influence the scaffold properties. Moreover, an alternative characterization of scaffolds via dielectric and free space measurement as a potential contactless and nondestructive measurement method is also highlighted.