Examination of intestinal ultrastructure, bowel wall apoptosis and tight junctions in the early phase of sepsis.

Gut hyperpermeability can be caused by either apoptosis of the intestinal epithelium or altered status, permeability or porosity of tight junctions. This project aims to elucidate these mechanisms in the early phase of sepsis. Eighteen male wild type mice were randomized to two groups.

µXRF Elemental Mapping of Bioresorbable Magnesium-Based Implants in Bone.

This study investigated the distribution of the elemental constituents of Mg-based implants at various stages of the degradation process in surrounding bone tissue, with a focus on magnesium (Mg), as the main component of the alloy, and yttrium (Y), due to its potential adverse health effects. The measurements were performed on the implant-bearing thin sections of rat bone in a time series of implant degradation between one and 18 months. Micro X-ray fluorescence analysis (μXRF) with a special spectrometer meeting the requirements for the measurements of low-Z elements was used.

Bone-implant degradation and mechanical response of bone surrounding Mg-alloy implants.

In the present paper, first results of the influence of the degradation of biodegradable materials on the hardness of the bone are presented in detail. For this purpose, different materials (Mg, Ti and biopolymers) were implanted into the femora of growing rats and bone cross sections were examined for the micro-hardness (MH). The aim of the present paper was to examine the mechanical response of the bone areas surrounding the implant at defined sites and at specified periods after implantation.

The potential of isotopically enriched magnesium to study bone implant degradation in vivo.

Unlabelled: This pilot study highlights the substantial potential of using isotopically enriched (non-radioactive) metals to study the fate of biodegradable metal implants. It was possible to show that magnesium (Mg) release can be observed by combining isotopic mass spectrometry and isotopic pattern deconvolution for data reduction, even at low amounts of Mg released a from slowly degrading Mg enriched (>99%) Mg metal. Following implantation into rats, structural in vivo changes were monitored by μCT.

Comparative biomechanical and radiological characterization of osseointegration of a biodegradable magnesium alloy pin and a copolymeric control for osteosynthesis.

Magnesium alloys offer great advantages as degradable implant material for pediatric fracture fixation and hold the potential to overcome certain critical shortcomings inherent to currently used degradable (co)polymers. Besides good biocompatibility and appropriate degradation kinetics, sufficient implant anchorage in host bone is critical to prevent implant failure. Bone-implant anchorage of biodegradable magnesium alloys, however, has not yet been related and compared to that of copolymers, their degradable counterparts currently in clinical use.

Influence of environment on the fatigue crack growth behaviour of 12% Cr steel.

In the present work, the influence of different environments on the fatigue crack growth behaviour of 12% Cr steam turbine blade steel is investigated. Fatigue crack growth rates (FCGRs) in the near threshold regime are measured with ultrasonic fatigue testing technique. Fatigue tests are performed in vacuum, air and different aqueous environments with defined chloride and oxygen content.

PHB, crystalline and amorphous magnesium alloys: promising candidates for bioresorbable osteosynthesis implants?

In this study various biodegradable materials were tested for their suitability for use in osteosynthesis implants, in particular as elastically stable intramedullary nails for fracture treatment in paediatric orthopaedics. The materials investigated comprise polyhydroxybutyrate (PHB), which belongs to the polyester family and is produced by microorganisms, with additions of ZrO2 and a bone graft substitute; two crystalline magnesium alloys with significantly different degradation rates ZX50 (MgZnCa, fast) and WZ21 (MgYZnCa, slow); and MgZnCa bulk metallic glasses (BMG). Push-out tests were conducted after various implantation times in rat femur meta-diaphysis to evaluate the shear forces between the implant material and the bone.

Fracture tolerance of reaction wood (yew and spruce wood in the TR crack propagation system).

The fracture properties of spruce and yew were studied by in-situ loading in an environmental scanning microscope (ESEM). Loading was performed with a micro-wedge splitting device in the TR-crack propagation direction. The emphasis was laid on investigating the main mechanisms responsible for a fracture tolerant behavior with a focus on the reaction wood.

Bone-implant interface strength and osseointegration: Biodegradable magnesium alloy versus standard titanium control.

Previous research on the feasibility of using biodegradable magnesium alloys for bone implant applications mainly focused on biocompatibility and corrosion resistance. However, successful clinical employment of endosseous implants is largely dependent on biological fixation and anchorage in host bone to withstand functional loading. In the present study, we therefore aimed to investigate whether bone-implant interface strength and osseointegration of a novel biodegradable magnesium alloy (Mg-Y-Nd-HRE, based on WE43) is comparable to that of a titanium control (Ti-6Al-7Nb) currently in clinical use.

Micromotion at the fracture site after tibial nailing with four unreamed small-diameter nails--a biomechanical study using a distal tibia fracture model.

Background: Intramedullary nailing is the treatment of choice in tibia fractures allowing for closed fracture reduction and internal fixation. Small-diameter nails that preserve the endosteal blood supply act as load-sharing devices after proximal and distal locking. Despite fracture healing is influenced by movements at the fracture gap, no data are available reporting on the micromovements at the fracture site if small-diameter nails were used.

Factors influencing interlocking screw failure in unreamed small diameter nails--a biomechanical study using a distal tibia fracture model.

Background: Unreamed tibia nails with small diameters are increasingly used for fracture fixation. However, little is known about the fatigue strength of proximal and distal interlocking screws in those nails. To date, no data are available reporting on mechanical differences of solid compared to cannulated tibial nails.

Cell-wall recovery after irreversible deformation of wood.

The remarkable mechanical properties of biological materials reside in their complex hierarchical architecture and in specific molecular mechanistic phenomena. The fundamental importance of molecular interactions and bond recovery has been suggested by studies on deformation and fracture of bone and nacre. Like these mineral-based materials, wood also represents a complex nanocomposite with excellent mechanical performance, despite the fact that it is mainly based on polymers.