Biomechanical comparison of screw-based zoning of PHILOS and Fx proximal humerus plates

Background Treatment of proximal humerus fractures with locking plates is associated with complications. We aimed to compare the biomechanical effects of removing screws and blade of a fixed angle locking plate and hybrid blade plate, on a two-part fracture model. Methods Forty-five synthetic humeri were divided into nine groups where four were implanted with a hybrid blade plate and the remaining with locking plate, to treat a two-part surgical neck fracture. Plates’ head screws and blades were divided into zones based on their distance from fracture site. Two groups acted as a control for each plate and the remaining seven had either a vacant zone or blade swapped with screws. For elastic cantilever bending, humeral head was fixed and the shaft was displaced 5 mm in extension, flexion, valgus and varus direction. Specimens were further loaded in varus direction to investigate their plastic behaviour. Results In both plates, removal of inferomedial screws or blade led to a significantly larger drop in varus construct stiffness than other zones. In blade plate, insertion of screws in place of blade significantly increased the mean extension, flexion valgus and varus bending stiffness (24.458%/16.623%/19.493%/14.137%). In locking plate, removal of screw zones proximal to the inferomedial screws reduced extension and flexion bending stiffness by 26–33%. Conclusions Although medial support improved varus stability, two inferomedial screws were more effective than blade. Proximal screws are important for extension and flexion. Mechanical consequences of screw removal should be considered when deciding the number and choice of screws and blade in clinic

Parametric design optimisation of proximal humerus plates based on finite element method

Optimal treatment of proximal humerus fractures remains controversial. Locking plates offer theoretical advantages but are associated with complications in the clinic. This study aimed to perform parametric design optimisation of proximal humerus plates to enhance their mechanical performance. A finite element (FE) model was developed that simulated a two-part proximal humerus fracture that had been treated with a Spatial Subchondral Support (S3) plate and subjected to varus bending. The FE model was validated against in vitro biomechanical test results. The predicted load required to apply 5 mm cantilever varus bending was only 0.728% lower. The FE model was then used to conduct a parametric optimisation study to determine the orientations of inferomedial plate screws that would yield minimum fracture gap change (i.e. optimal stability). The feasible design space was automatically identified by imposing clinically relevant constraints, and the creation process of each FE model for the design optimisation was automated. Consequently, 538 FE models were generated, from which the obtained optimal model had 4.686% lower fracture gap change (0.156 mm) than that of the manufacturer’s standard plate. Whereas its screws were oriented towards the inferomedial region and within the range of neck-shaft angle of a healthy subject. The methodology presented in this study promises future applications in patient-specific design optimisation of implants for other regions of the human body

Role of Nrf2 Dysfunction in Uremia-Associated Intestinal Inflammation and Epithelial Barrier Disruption

Aims: To study the expression profile of inflammatory and tight junction proteins in the colon from CKD rats compared to healthy controls, and demonstrate the role of Nrf2 (transcription factor nuclear factor erythroid 2-related factor 2) using a potent Nrf2 activator

Optimisation of hydrolysis conditions for antioxidant hydrolysate production from whey protein isolates using response surface methodology

peer-reviewedThe hydrolysates of whey protein isolates (WPI) by papain were found to possess antioxidant activity. Response surface methodology (RSM) was used to improve the antioxidant activity of these hydrolysates. The model was validated and shown to be statistically adequate and accurate in predicting the response. For both 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging activity and reducing power responses, the optimised conditions were achieved at an enzyme to substrate ratio (E/S, w/w) of 2.22%, hydrolysis time of 3.60 h, and hydrolysis temperature of 45.70 °C. Under the optimised conditions, DPPH radical-scavenging activity of the hydrolysates of WPI was 31.48% and the reducing power was 0.612 at 700 nm. The results of confirmation experiments indicated that the model was powerful and suitable for estimation of the experimental value. The hydrolysate of WPI has potential application as an antioxidant in food products.National Science Technology Minister of Chin

High-pressure experiments provide insights into the Mantle Transition Zone history of chromitite in Tibetan ophiolites

The chromitites in the Luobusha ophiolite (Tibet) have been proposed as messengers from the deep mantle. The exsolution of diopside, MgSiO₃ and coesite in chromite from these bodies has been used to argue that the chromite previously existed as a phase with the CaFe₂O₄ structure (idealized composition (Mg, Fe)(Cr, Al)₂O₄), an indicator of Mantle Transition Zone (MTZ) conditions. However, evidence about the stability of the CaFe₂O₄-structured phase and its formation mechanism are limited. Here we present experimental evidence for the depth of metamorphism and subsequent petrogenesis of the podiform chromitite. The CaFe₂O₄-structured phase was observed at ∼14–18 GPa, and can contain several weight percent of CaO and SiO₂. Partial-melting experiments show that chromite cannot be formed through direct crystallization in the MTZ. Therefore, we suggest that the Tibetan chromitites formed under shallow conditions, were then subducted, and were metamorphosed near the top of MTZ. During the tectonics/buoyancy-driven ascent of the enclosing peridotites, the CaFe₂O₄-phase transformed to chromite at depths of ∼400 km, accompanied by the simultaneous exsolution of diopside and other phases, which were then preserved during transportation to shallow depths. These observations provide a new window into the processes of mantle geodynamics, and constraints on mantle convection in major collision zones.8 page(s