Long-term in vivo degradation of Mg-Zn-Ca elastic stable intramedullary nails and their influence on the physis of juvenile sheep.

The use of bioresorbable magnesium (Mg)-based elastic stable intramedullary nails (ESIN) is highly promising for the treatment of pediatric long-bone fractures. Being fully resorbable, a removal surgery is not required, preventing repeated physical and psychological stress for the child. Further, the osteoconductive properties of the material support fracture healing. Nowadays, ESIN are exclusively implanted in a non-transphyseal manner to prevent growth discrepancies, although transphyseal implantation would often be required to guarantee optimized fracture stabilization. Here, we investigated the influence of trans-epiphyseally implanted Mg-Zinc (Zn)-Calcium (Ca) ESIN on the proximal tibial physis of juvenile sheep over a period of three years, until skeletal maturity was reached. We used the two alloying systems ZX10 (Mg-1Zn-0.3Ca, in wt%) and ZX00 (Mg-0.3Zn-0.4Ca, in wt%) for this study. To elaborate potential growth disturbances such as leg-length differences and axis deviations we used a combination of in vivo clinical computed tomography (cCT) and ex vivo micro CT (µCT), and also performed histology studies on the extracted bones to obtain information on the related tissue. Because there is a lack of long-term data regarding the degradation performance of magnesium-based implants, we used cCT and µCT data to evaluate the implant volume, gas volume and degradation rate of both alloying systems over a period of 148 weeks. We show that transepiphyseal implantation of Mg-Zn-Ca ESIN has no negative influence on the longitudinal bone growth in juvenile sheep, and that there is no axis deviation observed in all cases. We also illustrate that 95 % of the ESIN degraded over nearly three years, converging the time point of full resorption. We thus conclude that both, ZX10 and ZX00, constitute promising implant materials for the ESIN technique.

Material modifications enhancing the antibacterial properties of two biodegradable poly(3-hydroxybutyrate) implants.

The aim of this study was to evaluate the antimicrobial efficacy of adding a gentamicin palmitate (GP) coating and zirconium dioxide (ZrO2) to biodegradable poly(3-hydroxybutyrate) (PHB) to reduce biofilm formation. Cylindrical pins with and without a coating were incubated in Müller-Hinton broth inoculated with 2 × 105 colony-forming units (CFU) ml-1 of Staphylococcus aureus for 2 d or 7 d, then sonicated to disrupt biofilms. Pure PHB (PHB + GP) and PHB pins with ZrO2 added (PHBzr + GP) were coated with GP and compared with PHB pins lacking a coating (PHB). Cells (CFU) were counted to quantify the number of bacteria in the biofilm and a cell proliferation assay was employed to evaluate metabolic activity, and scanning electron microscopy (SEM) was performed to visualize the structure of the biofilm. After 2 d of incubation there were significantly more cells in biofilms on PHB pins than PHB + GP and PHBzr + GP pins (p < 0.0001), and cells in the sonication fluid obtained from GP-coated pins exhibited significantly lower metabolic activity than cells from uncoated PHB pins (p < 0.0001). After 7 d of incubation metabolic activity was lowest for PHBzr + GP, with significant differences between PHB and PHBzr + GP (p = 0.001). SEM revealed more cells attached to the surface, and more structured biofilms, on pins without a coating. Coating pins with GP significantly reduced early biofilm formation on PHB implants. This could lower the potential risk of surgical site infections when using PHB implants. Addition of ZrO2 might further enhance the antibacterial properties. Such modification of the implant material should therefore be considered when developing new biodegradable PHB implants.

[Pediatric pelvic trauma]. / Kindliches Beckentrauma.

The main injury mechanism of rare pelvic girdle injuries in children is high-energy trauma with a high rate of accompanying injuries and a mortality up to 6%. Anatomical features often result in complex pelvic trauma. Emergency treatment is based on established standards in adults. Definitive treatment is mostly conservative and implants adapted for children are increasingly used. Long-term consequences have to be considered, especially after unstable pelvic ring injuries. A correlation exists between clinical and radiological results. Due to the difficult radiological assessment, acetabular injuries are easily overlooked. The Salter-Harris classification appears to be prognostically useful. Most acetabular injuries can be treated conservatively. Considerable displacement or additional intra-articular injuries necessitate open reduction and internal fixation. Frequent follow-up examinations up to the end of the growth phase avoid posttraumatic acetabular dysplasia being overlooked.

The role of zinc in the biocorrosion behavior of resorbable Mg‒Zn‒Ca alloys.

Zinc- and calcium-containing magnesium alloys, denominated ZX alloys, excel as temporary implant materials because of their composition made of physiologically essential minerals and lack of commonly used rare-earth alloying elements. This study documents the specific role of nanometric intermetallic particles (IMPs) on the in vitro and in vivo biocorrosion behavior of two ZX-lean alloys, Mg‒Zn1.0‒Ca0.3 (ZX10) and Mg‒Zn1.5‒Ca0.25 (ZX20) (in wt.%). These alloys were designed according to thermodynamic considerations by finely adjusting the nominal Zn content towards microstructures that differ solely in the type of phase composing the IMPs: ZX10, with 1.0 wt.% Zn, hosts binary Mg2Ca-phase IMPs, while ZX20, with 1.5 wt.% Zn, hosts ternary IM1-phase IMPs. Electrochemical methods and the hydrogen-gas evolution method were deployed and complemented by transmission electron microscopy analyses. These techniques used in concert reveal that the Mg2Ca-type IMPs anodically dissolve preferentially and completely, while the IM1-type IMPs act as nano-cathodes, facilitating a faster dissolution of ZX20 compared to ZX10. Additionally, a dynamically increasing cathodic reactivity with progressing dissolution was observed for both alloys. This effect is explained by redeposits of Zn on the corroding surface, which act as additional nano-cathodes and facilitate enhanced cathodic reaction kinetics. The higher degradation rate of ZX20 was verified in vivo via micro-computed tomography upon implantation of both materials into femurs of Sprague DawleyⓇ rats. Both alloys were well integrated with direct bone‒implant contact observable 4 weeks post operationem, and an appropriately slow and homogeneous degradation could be observed with no adverse effects on the surrounding tissue. The results suggest that both alloys qualify as new temporary implant materials, and that a minor adjustment of the Zn content may function as a lever for tuning the degradation rate towards desired applications. STATEMENT OF SIGNIFICANCE: In Mg‒Zn‒Ca (ZX)-lean alloys Zn is the most electropositive element, and thus requires special attention in the investigation of biocorrosion mechanisms acting on these alloys. Even a small increase of only 0.5 wt.% Zn is shown to accelerate the biodegradation rate in both simulated body conditions and in vivo. This is possible due to Zn's role in influencing the type of intermetallic particles (IMPs) in these alloys. These IMPs in turn, even though minute in size, are shown to govern the biocorrosion behavior on the macroscopic scale. The deep understanding gained in this study on the role of Zn and of the IMP type it governs is crucial to ensuring a safe and controllable implant degradation.

Organizational uptake of NICE guidance in promoting employees' psychological health.

BACKGROUND: Annual costs to organizations of poor mental health are estimated to be between £33 billion and £42 billion. The UK's National Institute for Clinical Excellence (NICE) has produced evidence-based guidance on improving employees' psychological health, designed to encourage organizations to take preventative steps in tackling this high toll. However, the extent of implementation is not known outside the National Health Service. AIMS: To assess the awareness and implementation of NICE guidance on workplace psychological health. METHODS: A total of 163 organizations participated in a survey of UK-based private, public and third sector organizations employing an accumulated minimum of 322 033 workers. RESULTS: Seventy-seven per cent of organizations were aware of the NICE guidance for improving mental well-being in the workplace, but only 37% were familiar with its recommendations. Less than half were aware of systems in place for monitoring employees' mental well-being and only 12% confirmed that this NICE guidance had been implemented in their workplace. Where employee health and well-being featured as a regular board agenda item, awareness and implementation of NICE guidance were more likely. Significant associations were found between organizational sector and size and uptake of many specific features of NICE guidance. CONCLUSIONS: The majority of organizations are aware of NICE guidance in general, but there is a wide gap between this and possession of detailed knowledge and implementation. The role of sector and size of organization is relevant to uptake of some features of NICE guidance, although organizational leadership is important where raised awareness and implementation are concerned.

Comparison of a resorbable magnesium implant in small and large growing-animal models.

Fracture treatment in children needs new implant materials to overcome disadvantages associated with removal surgery. Magnesium-based implants constitute a biocompatible and bioresorbable alternative. In adults and especially in children, implant safety needs to be evaluated. In children the bone turnover rate is higher and implant material might influence growth capacity, and the long-term effect of accumulated particles or ions is more critical due to the host's prolonged post-surgery lifespan. In this study we aimed to investigate the degradation behavior of ZX00 (Mg-0.45Zn-0.45Ca; in wt.%) in a small and a large animal model to find out whether there is a difference between the two models (i) in degradation rate and (ii) in bone formation and in-growth. Our results 6, 12 and 24 weeks after ZX00 implantation showed no negative effects on bone formation and in-growth, and no adverse effects such as fibrotic or sclerotic encapsulation. The degradation rate did not significantly differ between the two growing-animal models, and both showed slow and homogeneous degradation performance. Our conclusion is that small animal models may be sufficient to investigate degradation rates and provide preliminary evidence on bone formation and in-growth of implant materials in a growing-animal model. STATEMENT OF SIGNIFICANCE: The safety of implant material is of the utmost importance, especially in children, who have enhanced bone turnover, more growth capacity and longer postoperative lifespans. Magnesium (Mg)-based implants have long been of great interest in pediatric orthopedic and trauma surgery, due to their good biocompatibility, biodegradability and biomechanics. In the study documented in this manuscript we investigated Mg-Zn-Ca implant material without rare-earth elements, and compared its outcome in a small and a large growing-animal model. In both models we observed bone formation and in-growth which featured no adverse effects such as fibrotic or sclerotic encapsulation, and slow homogeneous degradation performance of the Mg-based implant material.

Transcriptome analysis of Porphyromonas gingivalis and Acinetobacter baumannii in polymicrobial communities.

Acinetobacter baumannii is a nosocomial, opportunistic pathogen that causes several serious conditions including meningitis, septicemia, endocarditis, and pneumonia. It can be found in the oral biofilm, which may be a reservoir for pneumonia and chronic obstructive pulmonary disease. Subgingival colonization by A. baumannii is associated with chronic and aggressive periodontitis as well as refractory periodontal disease. Porphyromonas gingivalis, a keystone periodontal pathogen localized to subgingival plaque, is also implicated in several chronic conditions including aspiration pneumonia. Although both bacteria are found together in subgingival plaque and can cause multiple polymicrobial infections, nothing is known about the interactions between these two important human pathogens. In this study, we used RNA sequencing to understand the transcriptional response of both species as they adapt to heterotypic communities. Among the differentially regulated genes were those encoding a number of important virulence factors for both species including adhesion, biofilm formation, and protein secretion. Additionally, the presence of A. baumannii increased the abundance of P. gingivalis in model dual-species communities. Collectively these results suggest that both P. gingivalis and A. baumannii adapt to each other and have synergistic potential for increased pathogenicity. In identifying the mechanisms that promote pathogenicity and refractory disease, novel approaches to mitigate polymicrobial synergistic interactions may be developed to treat or prevent associated diseases.

In vivo and in vitro degradation comparison of pure Mg, Mg-10Gd and Mg-2Ag: a short term study.

The purpose of this study was to compare short term in vitro and in vivo biodegradation studies with low purity Mg (> 99.94 %), Mg-10Gd and Mg-2Ag designed for biodegradable implant applications. Three in vitro testing conditions were applied, using (i) phosphate buffered saline (PBS), (ii) Hank's balanced salt solution (HBSS) and (iii) Dulbecco's modified eagle medium (DMEM) in 5 % CO2 under sterile conditions. Gas evolution and mass loss (ML) were assessed, as well as the degradation layer, by elemental mapping and scanning electron microscopy (SEM). In vivo, implantations were performed on male Sprague-Dawley rats evaluating both, gas cavity volume and implant volume reduction by micro-computed tomography (µCT), 7 d after implantation. Samples were produced by casting, solution heat treatment and extrusion in disc and pin shape for the in vitro and in vivo experiments, respectively. Results showed that when the processing of the Mg sample varied, differences were found not only in the alloy impurity content and the grain size, but also in the corrosion behaviour. An increase of Fe and Ni or a large grain size seemed to play a major role in the degradation process, while the influence of alloying elements, such as Gd and Ag, played a secondary role. Results also indicated that cell culture conditions induced degradation rates and degradation layer elemental composition comparable to in vivo conditions. These in vitro and in vivo degradation layers consisted of Mg hydroxide, Mg-Ca carbonate and Ca phosphate.

Long-term in vivo degradation behavior and near-implant distribution of resorbed elements for magnesium alloys WZ21 and ZX50.

UNLABELLED: We report on the long-term effects of degrading magnesium implants on bone tissue in a growing rat skeleton using continuous in vivo micro-Computed Tomography, histological staining and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Two different magnesium alloys-one rapidly degrading (ZX50) and one slowly degrading (WZ21)-were used to evaluate the bone response and distribution of released Mg and Y ions in the femur of male Sprague-Dawley rats. Regardless of whether the alloy degrades rapidly or slowly, we found that bone recovers restitutio ad integrum after complete degradation of the magnesium implant. The degradation of the Mg alloys generates a significant increase in Mg concentration in the cortical bone near the remaining implant parts, but the Mg accumulation disappears after the implant degrades completely. The degradation of the Y-containing alloy WZ21 leads to Y enrichment in adjacent bone tissues and in newly formed bone inside the medullary space. Locally high Y concentrations suggest migration not only of Y ions but also of Y-containing intermetallic particles. However, after the full degradation of the implant the Y-enrichment disappears almost completely. Hydrogen gas formation and ion release during implant degradation did not harm bone regeneration in our samples. STATEMENT OF SIGNIFICANCE: Magnesium is generally considered to be one of the most attractive base materials for biodegradable implants, and many magnesium alloys have been optimized to adjust implant degradation. Delayed degradation, however, generates prolonged presence in the organism with the risk of foreign body reactions. While most studies so far have only ranged from several weeks up to 12months, the present study provides data for complete implant degradation and bone regeneration until 24months, for two magnesium alloys (ZX50, WZ21) with different degradation characteristics. µCT monitoring, histological staining and LA-ICP-MS illustrate the distribution of the elements in the neighboring bony tissues during implant degradation, and reveal in particular high concentrations of the rare-earth element Yttrium.

Penile intracavernosal pillars: lessons from anatomy and potential implications for penile prosthesis placement.

The objective of this study was to anatomically describe the relationship of penile intracavernosal pillars to penile surgery, specifically corporal dilation during penile prosthesis placement. Corpora cavernosa from four embalmed male cadavers were dissected and subjected to probe dilation. Corpora were cross-sectioned and examined for the gross presence and location of pillars and dilated spaces. Infrapubic penile prosthesis insertion was performed on one fresh-frozen cadaveric male pelvis, followed by cross-sectioning. A single patient had intracavernosal pillars examined intraoperatively during Peyronie's plaque excision and penile prosthesis insertion. Intracavernosal pillars were identified in all cadavers and one surgical patient, passing obliquely from the dorsolateral tunica albuginea across the sinusoidal space to the ventral intercorporal septum. This delineated each corpus into two potential compartments for dilation: dorsomedial and ventrolateral. Dorsal dilation seated instruments and prosthetics satisfactorily in the dorsal mid glans and provided additional tissue coverage over weak ventral areas of the tunica albuginea, while ventrolateral dilation appeared to result in ventral seating and susceptibility to perforation. Intracavernosal pillars are an important anatomic consideration during penile prosthesis placement. Dorsal dilation appears to result in improved distal seating of cylinder tips, which may be protective against tip malposition, perforation or subsequent erosion.

Innate immunity in HIV-1 infection: epithelial and non-specific host factors of mucosal immunity- a workshop report.

The interplay between HIV-1 and epithelial cells represents a critical aspect in mucosal HIV-1 transmission. Epithelial cells lining the oral cavity cover subepithelial tissues, which contain virus-susceptible host cells including CD4(+) T lymphocytes, monocytes/macrophages, and dendritic cells. Oral epithelia are among the sites of first exposure to both cell-free and cell-associated virus HIV-1 through breast-feeding and oral-genital contact. However, oral mucosa is considered to be naturally resistant to HIV-1 transmission. Oral epithelial cells have been shown to play a crucial role in innate host defense. Nevertheless, it is not clear to what degree these local innate immune factors contribute to HIV-1 resistance of the oral mucosa. This review paper addressed the following issues that were discussed at the 7th World Workshop on Oral Health and Disease in AIDS held in Hyderabad, India, during November 6-9, 2014: (i) What is the fate of HIV-1 after interactions with oral epithelial cells?; (ii) What are the keratinocyte and other anti-HIV effector oral factors, and how do they contribute to mucosal protection?; (iii) How can HIV-1 interactions with oral epithelium affect activation and populations of local immune cells?; (iv) How can HIV-1 interactions alter functions of oral epithelial cells?

Simulation as a set-up for technical proficiency: can a virtual warm-up improve live fibre-optic intubation?

BACKGROUND: Fibre-optic intubation (FOI) is an advanced technical skill, which anaesthesia residents must frequently perform under pressure. In surgical subspecialties, a virtual 'warm-up' has been used to prime a practitioner's skill set immediately before performance of challenging procedures. This study examined whether a virtual warm-up improved the performance of elective live patient FOI by anaesthesia residents. METHODS: Clinical anaesthesia yr 1 and 2 (CA1 and CA2) residents were recruited to perform elective asleep oral FOI. Residents either underwent a 5 min, guided warm-up (using a bronchoscopy simulator) immediately before live FOI on patients with predicted normal airways or performed live FOI on similar patients without the warm-up. Subjects were timed performing FOI (from scope passing teeth to viewing the carina) and were graded on a 45-point skill scale by attending anaesthetists. After a washout period, all subjects were resampled as members of the opposite cohort. Multivariate analysis was performed to control for variations in previous FOI experience of the residents. RESULTS: Thirty-three anaesthesia residents were recruited, of whom 22 were CA1 and 11 were CA2. Virtual warm-up conferred a 37% reduction in time for CA1s (mean 35.8 (SD 3.2) s vs. 57 (SD 3.2) s, P<0.0002) and a 26% decrease for CA2s (mean 23 (SD 1.7) s vs. 31 (SD 1.7) s, P=0.0118). Global skill score increased with warm-up by 4.8 points for CA1s (mean 32.8 (SD 1.2) vs. 37.6 (SD 1.2), P=0.0079) and 5.1 points for CA2s (37.7 (SD 1.1) vs. 42.8 (SD 1.1), P=0.0125). Crossover period and sequence did not show a statistically significant association with performance. CONCLUSIONS: Virtual warm-up significantly improved performance by residents of FOI in live patients with normal airway anatomy, as measured both by speed and by a scaled evaluation of skills.

Reaction of bone nanostructure to a biodegrading Magnesium WZ21 implant - A scanning small-angle X-ray scattering time study.

Understanding the implant-bone interaction is of prime interest for the development of novel biodegrading implants. Magnesium is a very promising material in the class of biodegrading metallic implants, owing to its mechanical properties and excellent immunologic response during healing. However, the influence of degrading Mg implants on the bone nanostructure is still an open question of crucial importance for the design of novel Mg implant alloys. This study investigates the changes in the nanostructure of bone following the application of a degrading WZ21 Mg implant (2wt% Y, 1wt% Zn, 0.25wt% Ca and 0.15wt% Mn) in a murine model system over the course of 15months by small angle X-ray scattering. Our investigations showed a direct response of the bone nanostructure after as little as 1month with a realignment of nano-sized bone mineral platelets along the bone-implant interface. The growth of new bone tissue after implant resorption is characterized by zones of lower mineral platelet thickness and slightly decreased order in the stacking of the platelets. The preferential orientation of the mineral platelets strongly deviates from the normal orientation along the shaft and still roughly follows the implant direction after 15months. We explain our findings by considering geometrical, mechanical and chemical factors during the process of implant resorption. STATEMENT OF SIGNIFICANCE: The advancement of surgical techniques and the increased life expectancy have caused a growing demand for improved bone implants. Ideally, they should be bio-resorbable, support bone as long as necessary and then be replaced by healthy bone tissue. Magnesium is a promising candidate for this purpose. Various studies have demonstrated its excellent mechanical performance, degradation behaviour and immunologic properties. The structural response of bone, however, is not well known. On the nanometer scale, the arrangement of collagen fibers and calcium mineral platelets is an important indicator of structural integrity. The present study provides insight into nanostructural changes in rat bone at different times after implant placement and different implant degradation states. The results are useful for further improved magnesium alloys.

Transforming growth factor-ß1 sustains the survival of Foxp3(+) regulatory cells during late phase of oropharyngeal candidiasis infection.

As CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play crucial immunomodulatory roles during infections, one key question is how these cells are controlled during antimicrobial immune responses. Mechanisms controlling their homeostasis are central to ensure efficient protection against pathogens, as well as to control infection-associated immunopathology. Here we studied how their viability is regulated in the context of mouse oropharyngeal candidiasis (OPC) infection, and found that these cells show increased protection from apoptosis during late phase of infection and reinfection. Tregs underwent reduced cell death because they are refractory to T cell receptor restimulation-induced cell death (RICD). We confirmed their resistance to RICD, using mouse and human Tregs in vitro, and by inducing α-CD3 antibody-mediated apoptosis in vivo. The enhanced viability is dependent on increased transforming growth factor-ß1 (TGF-ß1) signaling that results in upregulation of cFLIP (cellular FLICE (FADD-like IL-1ß-converting enzyme)-inhibitory protein) in Tregs. Protection from cell death is abrogated in the absence of TGF-ß1 signaling in Tregs during OPC infection. Taken together, our data unravel the previously unrecognized role of TGF-ß1 in promoting Treg viability, coinciding with the pronounced immunomodulatory role of these cells during later phase of OPC infection, and possibly other mucosal infections.

Magnesium from bioresorbable implants: Distribution and impact on the nano- and mineral structure of bone.

Biocompatibility is a key issue in the development of new implant materials. In this context, a novel class of biodegrading Mg implants exhibits promising properties with regard to inflammatory response and mechanical properties. The interaction between Mg degradation products and the nanoscale structure and mineralization of bone, however, is not yet sufficiently understood. Investigations by synchrotron microbeam x-ray fluorescence (µXRF), small angle x-ray scattering (µSAXS) and x-ray diffraction (µXRD) have shown the impact of degradation speed on the sites of Mg accumulation in the bone, which are around blood vessels, lacunae and the bone marrow. Only at the highest degradation rates was Mg found at the implant-bone interface. The Mg inclusion into the bone matrix appeared to be non-permanent as the Mg-level decreased after completed implant degradation. µSAXS and µXRD showed that Mg influences the hydroxyl apatite (HAP) crystallite structure, because markedly shorter and thinner HAP crystallites were found in zones of high Mg concentration. These zones also exhibited a contraction of the HAP lattice and lower crystalline order.

Adhesive strength of bone-implant interfaces and in-vivo degradation of PHB composites for load-bearing applications.

Aim of this study was to evaluate the response of bone to novel biodegradable polymeric composite implants in the femora of growing rats. Longitudinal observation of bone reaction at the implant site (BV/TV) as well as resorption of the implanted pins were monitored using in vivo micro-focus computed tomography (µCT). After 12, 24 and 36 weeks femora containing the implants were explanted, scanned with high resolution ex vivo µCT, and the surface roughness of the implants was measured to conclude on the ingrowth capability for bone tissue. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to observe changes on the surface of Polyhydroxybutyrate (PHB) during degradation and cell ingrowth. Four different composites with zirconium dioxide (ZrO2) and Herafill(®) were compared. After 36 weeks in vivo, none of the implants did show significant degradation. The PHB composite with ZrO2 and a high percentage (30%) of Herafill® as well as the Mg-alloy WZ21 showed the highest values of bone accumulation (increased BV/TV) around the implant. The lowest value was measured in PHB with 3% ZrO2 containing no Herafill®. Roughness measurements as well as EDX and SEM imaging could not reveal any changes on the PHB composites׳ surfaces. Biomechanical parameters, such as the adhesion strength between bone and implant were determined by measuring the shear strength as well as push-out energy of the bone-implant interface. The results showed that improvement of these mechanical properties of the studied PHBs P3Z, P3Z10H and P3Z30H is necessary in order to obtain appropriate load-bearing material. The moduli of elasticity, tensile strength and strain properties of the PHB composites are close to that of bone and thus promising. Compared to clinically used PLGA, PGA and PLA materials, their additional benefit is an unchanged local pH value during degradation, which makes them well tolerated by cells and immune system. They might be used successfully for personalized 3D printed implants or as coatings of rapidly dissolving implants.

Influence of trace impurities on the in vitro and in vivo degradation of biodegradable Mg-5Zn-0.3Ca alloys.

The hydrogen evolution method and animal experiments were deployed to investigate the effect of trace impurity elements on the degradation behavior of high-strength Mg alloys of type ZX50 (Mg-5Zn-0.3Ca). It is shown that trace impurity elements increase the degradation rate, predominantly in the initial period of the tests, and also increase the material's susceptibility to localized corrosion attack. These effects are explained on the basis of the corrosion potential of the intermetallic phases present in the alloys. The Zn-rich phases present in ZX50 are nobler than the Mg matrix, and thus act as cathodic sites. The impurity elements Fe and Mn in the alloy of conventional purity are incorporated in these Zn-rich intermetallic phases and therefore increase their cathodic efficiency. A design rule for circumventing the formation of noble intermetallic particles and thus avoiding galvanically accelerated dissolution of the Mg matrix is proposed.

Is it safe to leave an ECMO circuit primed?

Extracorporeal membrane oxygenation (ECMO) is a means of life support for failing patients who require extreme life-saving measures due to failure of their heart, lungs or both organs. In a patient suffering cardiac arrest, the faster circulation via cardiopulmonary resuscitation (CPR) can be instituted the better the outcome is. If an ECMO circuit needs to be built and primed it may add significant minutes to the response time. The purpose of this study is to test for any growth in primed ECMO circuits at given time intervals to prove the safety of leaving an ECMO circuit primed. This, in turn, may lead to decreased response time, with an arrest and the placement of the arresting patient on ECMO. Five ECMO circuits were set up, primed and sampled for bacterial growth at 0, 24, 48 and 72 hours and then at one-week intervals, with an end point of four weeks. No bacterial growth was found at any point during the sampling process.