Biocompatibility and Bone Formation of Flexible, Cotton Wool-like PLGA/Calcium Phosphate Nanocomposites in Sheep

BACKGROUND: The purpose of this preliminary study was to assess the in vivo performance of synthetic, cotton wool-like nanocomposites consisting of a biodegradable poly(lactide-co-glycolide) fibrous matrix and containing either calcium phosphate nanoparticles (PLGA/CaP 60:40) or silver doped CaP nanoparticles (PLGA/Ag-CaP 60:40). Besides its extraordinary in vitro bioactivity the latter biomaterial (0.4 wt% total silver concentration) provides additional antimicrobial properties for treating bone defects exposed to microorganisms. MATERIALS AND METHODS: Both flexible artificial bone substitutes were implanted into totally 16 epiphyseal and metaphyseal drill hole defects of long bone in sheep and followed for 8 weeks. Histological and histomorphological analyses were conducted to evaluate the biocompatibility and bone formation applying a score system. The influence of silver on the in vivo performance was further investigated. RESULTS: Semi-quantitative evaluation of histology sections showed for both implant materials an excellent biocompatibility and bone healing with no resorption in the adjacent bone. No signs of inflammation were detectable, either macroscopically or microscopically, as was evident in 5 µm plastic sections by the minimal amount of inflammatory cells. The fibrous biomaterials enabled bone formation directly in the centre of the former defect. The area fraction of new bone formation as determined histomorphometrically after 8 weeks implantation was very similar with 20.5 ± 11.2 % and 22.5 ± 9.2 % for PLGA/CaP and PLGA/Ag-CaP, respectively. CONCLUSIONS: The cotton wool-like bone substitute material is easily applicable, biocompatible and might be beneficial in minimal invasive surgery for treating bone defects

Random cross-species identification of a gene encoding for an inorganic pyrophosphatase in the uncultivable hemotrophic bacterium Mycoplasma suis

Zusammenfassung In der vorliegenden Arbeit wurden zwei M. suis-Genbibliotheken auf die Gene Enolase und Pyruvatdehydrogenase (PDH) untersucht. Für die „cross species identification“ wurden DNA Sonden aus dem Enolase- und PDH-Gen des nahe verwandten humanpathogenen Agens M. pneumoniae verwendet. Um die in den Genbibliotheken zu etwa 90% enthaltenen Escherichia (E.) coli-Klone mit Inserts aus porziner DNA auszusortieren, wurden sämtliche Klone zunächst mit einer Biotin-markierten DNA-Sonde gegen porzine DNA hybridisiert. Sämtliche Klone mit positiven Hybridisierungsreaktionen mit porziner DNA wurden ausselektiert. Bei insgesamt 600 Klonen fiel diese DNA-Hybridisierung negativ aus, so dass sie als potentielle Träger eines M. suis-DNA-inserts gelten konnten. In Southern blot-Analysen der 600 E. coli-Klone mit den DNA-Sonden gegen M. pneumoniae Enolase und PDH konnten 30 Klone identifiziert werden, die mit einer der beiden Sonden spezifisch hybridisierten. Durch Sequenzanalyse der DNA-inserts wurde das Gen für eine M. suis-spezifische anorganische Pyrophosphatase (ppA) gefunden. Das ppA-Gen hat eine Grösse von 495 bp; die Homologie zu analogen Genen anderer pathogener Mycoplasmen beträgt 53-55%. Der GC-Gehalt beträgt 32%. Die prokaryotische anorganische Pyrophosphatase spielt im bakteriellen Energiestoffwechsel sowie im bakteriellen Protein- und Nukleinsäuremetabolismus eine wichtige Rolle und könnte ein neues Target für antibakterielle Wirkstoffe darstellen. Summary Genome sequence analysis of Mycoplasma suis is hampered due to the lack of an appropriate in vitro cultivating system. The organism has still to be purified from blood samples of experimentally infected pigs, which is linked with technical difficulties. Therefore, little is known about the genome of M. suis. For this work a cross-species random approach, based upon Southern blot, was considered in order to identify novel genes. Two shotgun M. suis genomic libraries were screened using either M. pneumoniae enolase or pyruvate dehydrogenase (PDH) probes. Using these two enzymes as probes is based on recent gained insights of their pathogenicity in mycoplasma infections. Following this strategy the complete open reading frame of a putative M. suis inorganic pyrophosphatase (ppA) was found by hybridizising with a M. pneumoniae enolase probe. The positive hybridization signal is considered to result from the DNA homology of 45% between the M. suis ppA and the M. pneumoniae enolase. The encoding gene ppA is 495 bp in size. The deduced amino acid sequence showed an overall similarity of 53 to 55% with inorganic pyrophosphatases of other pathogenic mycoplasmas, and a GC-content of 32%. This study demonstrates the feasibility and the encountered difficulties of a random cross- species approach to identify novel genes of an uncultivable agent like M. suis

Preliminary study on carprofen concentration measurements after transcutaneous treatment with Vetdrop® in a microfracture joint defect model in sheep.

BackgroundThe present preliminary study describes concentration time courses of the NSAID carprofen in the plasma and synovial fluid in a microfrature sheep model after transcutaneous treatments with a novel application device (Vetdrop®). To treat circumscribed inflammatory processes a transcutaneous application device could potentially be beneficial. After transcutaneous application normally lower systemic concentrations are measured which may reduce the incidence of side effects, whereas efficacy is still maintained.In this study carprofen was used based on its capacity to provide analgesia after orthopaedic procedures in sheep and it is considered that it may have a positive influence on the healing of cartilage in low concentrations.ResultsIn all transcutaneously treated animals, carprofen plasma concentrations exceeded those of synovial fluid, although plasma levels remained significantly reduced (300-fold) as compared to carprofen administered intravenously. Furthermore, in contrast to the intravenously treated animals, a modest accumulation of carprofen in plasma and synovial fluid was observed in the transcutaneously treated animals over the 6-week treatment period.ConclusionsThe transcutaneously administered carprofen using the Vetdrop® device penetrated the skin and both, plasma- and synovial concentrations could be measured repeatedly over time. This novel device may be considered a valuable transcutaneous drug delivery system

Transcatheter implantation of homologous “off-the-shelf” tissue engineered heart valves with self-repair capacity: long term functionality and rapid in vivo remodeling in sheep

Objectives: To evaluate long-term in-vivo functionality, host cell repopulation and remodeling of “off-theshelf” tissue-engineered transcatheter homologous heart-valves. Background: Transcatheter valve implantation has emerged as minimally-invasive alternative to conventional surgery in particular in elderly high-risk patients. However, currently used bio-prosthetic transcatheter valves are prone to progressive dysfunctional degeneration limiting their use in younger patients. To overcome these limitations the concept of tissue-engineered heart-valves with self-repair capacity has been introduced as next generation technology. Methods: In-vivo functionality, host cell repopulation, and matrix remodeling of tissue engineered homologous transcatheter heart valves (TEHVs) was evaluated up to 24weeks as pulmonary-valve replacements (transapical access) in sheep (n=12). As a control, tissue-composition and -structure were analyzed in identical not implanted TEHVs (n=5). Results: Transcatheter implantation was successful in all animals. Valve functionality was excellent displaying sufficient leaflet motion and coaptation with only minor paravalvular leakage in some animals. Mild central regurgitation was detected after 8 weeks increasing to moderate after 24weeks, correlating to a compromised leaflet coaptation. Mean and peak transvalvular pressure-gradients were 4.4±1.6 and 9.7±3.0mmHg. Significant matrix-remodeling was observed in the entire valve and corresponded with the rate of host cell repopulation. Conclusion: For the first time, the feasibility and long-term functionality of transcatheter based homologous off-the-shelf tissue-engineered heart-valves are demonstrated in a relevant preclinical-model. Such engineered heart-valves may represent an interesting alternative to current prostheses because of their rapid cellular repopulation, tissue remodeling and therewith self-repair capacity. The concept of homologous off-the-shelf tissue engineered heart-valves may therefore substantially simplify previous tissue-engineering concepts towards clinical translation

The dynamisation of locking plate osteosynthesis by means of dynamic locking screws (DLS)-An experimental study in sheep

In this in vivo study a new generation of locking screws was tested. The design of the dynamic locking screw (DLS) enables the dynamisation of the cortex underneath the plate (cis-cortex) and, therefore, allows almost parallel interfragmentary closure of the fracture gap. A 45° angle osteotomy was performed unilaterally on the tibia of 37 sheep. Groups of 12 sheep were formed and in each group a different osteotomy gap (0, 1 and 3mm) was fixed using a locking compression plate (LCP) in combination with the DLS. The healing process was monitored radiographically every 3 weeks for 6, respectively 12 weeks. After this time the sheep were sacrificed, the bones harvested and the implants removed. The isolated bones were evaluated in the micro-computed tomography unit, tested biomechanically and evaluated histologically. The best results of interfragmentary movement (IFM) were shown in the 0mm configuration. The bones of this group demonstrated histomorphometrically the most distinct callus formation on the cis-cortex and the highest torsional stiffness relative to the untreated limb at 12 weeks after surgery. This animal study showed that IFM stimulated the synthesis of new bone matrix, especially underneath the plate and thus, could solve a current limitation in normal human bone healing. The DLS will be a valuable addition to the locking screw technology and improve fracture healing

First WMT Shared Task on Sign Language Translation (WMT-SLT22)

International audienceThis paper is a brief summary of the First WMT Shared Task on Sign Language Translation (WMT-SLT22), a project partly funded by EAMT. The focus of this shared task is automatic translation between signed and spoken languages. Details can be found on our website 1 or in the findings paper (Müller et al., 2022)

Findings of the First WMT Shared Task on Sign Language Translation (WMT-SLT22)

This paper presents the results of the First WMT Shared Task on Sign Language Translation (WMT-SLT22). This shared task is concerned with automatic translation between signed and spoken languages. The task is novel in the sense that it requires processing visual information (such as video frames or human pose estimation) beyond the well-known paradigm of text-to-text machine translation (MT). The task featured two tracks, translating from Swiss German Sign Language (DSGS) to German and vice versa. Seven teams participated in this first edition of the task, all submitting to the DSGS-to-German track. Besides a system ranking and system papers describing state-of-the-art techniques, this shared task makes the following scientific contributions: novel corpora, reproducible baseline systems and new protocols and software for human evaluation. Finally, the task also resulted in the first publicly available set of system outputs and human evaluation scores for sign language translation