Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique

Calcium phosphate ceramics, commonly applied as bone graft substitutes, are a natural choice of scaffolding material for bone tissue engineering. Evidence shows that the chemical composition, macroporosity and microporosity of these ceramics influences their behavior as bone graft substitutes and bone tissue engineering scaffolds but little has been done to optimize these parameters. One method of optimization is to place focus on a particular parameter by normalizing the influence, as much as possible, of confounding parameters. This is difficult to accomplish with traditional fabrication techniques. In this study we describe a design based rapid prototyping method of manufacturing scaffolds with virtually identical macroporous architectures from different calcium phosphate ceramic compositions. Beta-tricalcium phosphate, hydroxyapatite (at two sintering temperatures) and biphasic calcium phosphate scaffolds were manufactured. The macro- and micro-architectures of the scaffolds were characterized as well as the influence of the manufacturing method on the chemistries of the calcium phosphate compositions. The structural characteristics of the resulting scaffolds were remarkably similar. The manufacturing process had little influence on the composition of the materials except for the consistent but small addition of, or increase in, a beta-tricalcium phosphate phase. Among other applications, scaffolds produced by the method described provide a means of examining the influence of different calcium phosphate compositions while confidently excluding the influence of the macroporous structure of the scaffolds

Interstate differences in insured unemployment: some recent evidence

Recent panel data is used to reconsider the determinants of interstate differences in the ratio of insured to total unemployment. It is concluded that previous research on the influence of replacement rates, duration of jobless spells and female labour force participation is robust, but it is found that political affiliations and attitudes could be more important, and unionization rates less important, than once believed.

Feasibility of a multidisciplinary intervention to help cancer patients return to work

This study evaluates feasibility of a multidisciplinary intervention combining occupational counselling with physical exercise to enhance cancer patients’ return to work, assesses whether care providers and patients were satisfied with the intervention, and describes barriers to and facilitators of execution. Newly diagnosed cancer patients, treated with chemotherapy and on sick leave from (self-)employment participated. Patients received counselling from an oncological occupational physician (OOP), were assessed by a sports physician, and performed a 12-week training programme supervised by physiotherapists. Care providers completed registration forms to collect data on reach, dose delivered and received in executing the protocol and were interviewed about their satisfaction and barriers to and facilitators of execution. Patients completed three questionnaires on satisfaction and usefulness of the intervention. Fifty-six per cent of all patients were eligible (reach). In total, 123 patients participated. For all intervention components dose delivered exceeded 75%; dose received ranged from 49%–79%. Overall, patients and care providers were satisfied and perceived the intervention as useful. Care providers considered the intervention feasible, while execution was facilitated by highly motivated patients and impeded by physical limitations hindering exercise. It is feasible to conduct this multidisciplinary intervention in cancer patients during curative treatment. Patients and care providers were satisfied with the intervention

Bioactive ceramic-based materials with designed reactivity for bone tissue regeneration

Bioactive ceramics have been used clinically to repair bone defects owing to their biological affinity to living bone; i.e. the capability of direct bonding to living bone, their so-called bioactivity. However, currently available bioactive ceramics do not satisfy every clinical application. Therefore, the development of novel design of bioactive materials is necessary. Bioactive ceramics show osteoconduction by formation of biologically active bone-like apatite through chemical reaction of the ceramic surface with surrounding body fluid. Hence, the control of their chemical reactivity in body fluid is essential to developing novel bioactive materials as well as biodegradable materials. This paper reviews novel bioactive materials designed based on chemical reactivity in body fluid