No abstract

Due to the non-bioactivity and poor conjunction performance of present cartilage prostheses, the main work here is to develop the bioactive glass-polyvinyl alcohol hydrogel articular cartilage/bone (BG-PVA/bone) composite implants. The essential criterion for a biomaterial to bond with living bone is well-matched mechanical properties as well as biocompatibility and bioactivity. In vitro studies on the formation of a surface layer of carbonate hydroxyl apatite (HCA) and the corresponding variation of the properties of biomaterials are imperative for their clinical application. In this paper, the mineralization behavior and variation of the interface properties of BG-PVA/bone composites were studied in vitro by using simulated body fluid (SBF). The mineralization and HCA layer formed on the interface between the BG-PVA hydrogel and bone in SBF could provide the composites with bioactivity and firmer combination. The compression property, shear strength and interface morphology of BG-PVA/bone composite implants varying with the immersion time in SBF were characterized. Also, the influence laws of the immersion time, content of BG in the composites and aperture of bones to the mineralization behavior and interface properties were investigated. The good mineralization behavior and enhanced conjunction performance of BG-PVA/bone composites demonstrated that this kind of composite implant might be more appropriate cartilage replacements.

No abstract

ABSTRACT:Composites of poly(d,l-lactide) (PDLLA) with hydroxylapatite (HA) and PDLLA with tertiary calcium phosphate (TCP) were prepared by in situ modification with methylenediphenyl diisocyanate (MDI) and molded by piston extrusion at temperature between T g and T m of PDLLA. Mechanical properties of the composites increased obviously when compared with the unmodified bioactive ceramic particles/PDLLA composites. The effect of MDI contents on mechanical properties of the composites was studied. At the optimum conditions of 1.0/1.0molar ratios of ONCO groups in MDI to OOH groups in PDLLA, bending strength 68.4 MPa and bending modulus 2281.5 MPa, were achieved in composite HA/PDLLA/MDI with 15 wt % HA. Both increased by nearly 30% when compared with that of solution cast HA/PDLLA composites. Interfacial adhesion and compatibility between PDLLA and bioactive ceramic particles (HA and TCP) were investigated. Scanning electron microscopy (SEM) indicated that the interface between HA particles and PDLLA was blurred and HA particles were closely surrounded by PDLLA matrix in HA/PDLLA/MDI composites. Oriented fibrils along with longitudinal direction of extrusion die were also observed on the surfaces of HA/PDLLA/MDI composite. It is confirmed that MDI has improved interfacial adhesion and compatibility between HA particles and PDLLA phase. Fibril structures formed in the extrusion, and it contributed a great deal in enhancing the mechanical properties.

Background Self-perceived burden (SPB) is an important predictor of quality of life (QoL) in patients with advanced cancer. However, the mechanism how SPB affects patients’ QoL remains unclear. This study aimed to examine the potential mediating roles of existential distress (ED) and anxiety in the relationship between SPB and QoL. Methods A multicenter cross-sectional study was conducted. 352 advanced cancer patients were recruited from three hospitals in southeast of China. The Self-perceived Burden Scale, the Existential Distress Scale, the Hospital Anxiety and Depression Scale, and the Quality-of-Life Concerns in the End of Life Questionnaire were adopted to collect data. Hayes’s bootstrapping method was used to analyze the data. Results SPB was negatively associated with QoL (P < 0.01). ED and anxiety partially mediated the relationship between SPB and QoL (P < 0.01). Moreover, ED had direct effects on anxiety, and sequentially QoL (P < 0.01). The serial multiple mediation model of SPB accounted for 73.25% of the variance in QoL in advanced cancer patients. Conclusions ED and anxiety are important mediating factors between SPB and QoL in advanced cancer patients. To improve patients’ QoL, comprehensive interventions for reducing anxiety and ED are highly recommended in clinical practices.