Arms Racing, Military Build-Ups and Dispute Intensity: Evidence from the Greek-Turkish Rivalry, 1985-2020

Arms races are linked in the public conscience to potential violence. Following gas discoveries in eastern Mediterranean, Greece and Turkey nearly came to blows in August 2020 and both states have enacted military expansion plans, further risking escalation. We present a novel approach to study the effect of military build-ups on dispute intensity, using monthly data on Turkish incursions into Greek-claimed airspace. Because airspace claims feature strongly in the dispute, these contestations represent an appropriate measure of the intensity with which Turkey pursues the conflict. Theoretically, we suggest that bilateral factors drive this intensity. We argue that increased Greek military capabilities deter incursions whereas increased Turkish military capabilities fuel them. Results from time-series models support the second expectation. Consequently, the study provides a novel methodological approach to studying interstate conflict intensity and shines new light on escalation dynamics in the Greek-Turkish dispute

Surface engineering of stainless steel materials by covalent collagen immobilization to improve implant biocompatibility

It was shown recently that the deposition of thin films of tantalum and tantalum oxide enhanced the long-term biocompatibility of stainless steel biomaterials due to an increase in their corrosion resistance. In this study, the authors used this tantalum oxide coating as a basis for covalent immobilization of a collagen layer, which should result in a further improvement of implant tissue integration. Because of the high degrdn. rate of natural collagen in vivo, covalent immobilization as well as carbodiimide induced crosslinking of the protein was performed. It was found that the combination of the silane-coupling agent aminopropyl triethoxysilane and the linker mol. N,N'-disulfosuccinimidyl suberate was a very effective system for collagen immobilizing. Mech. and enzymic stability testing revealed a higher stability of covalent bound collagen layers compared to phys. adsorbed collagen layers. The biol. response induced by the surface modifications was evaluated by in vitro cell culture with human mesenchymal stem cells as well as by in vivo s.c. implantation into nude mice. The presence of collagen clearly improved the cytocompatibility of the stainless steel implants which, nevertheless, significantly depended on the crosslinking degree of the collagen layer

Influence of different collagen species on physico-chemical properties of crosslinked collagen matrices

Collagen-based scaffolds are appealing products for the repair of cartilage defects using tissue engineering strategies. The present study investigated the species-related differences of collagen scaffolds with and without 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-hydroxysuccinimide-crosslinking. Resistance against collagenase digestion, swelling ratio, amino acid sequence, shrinkage temp., ultrastructural matrix morphol., crosslinking d. and stress-strain characteristics were detd. to evaluate the physico-chem. properties of equine- and bovine-collagen-based scaffolds. Three-factor ANOVA anal. revealed a highly significant effect of collagen type, crosslinking and time on degrdn. of the collagen samples by collagenase treatment. Crosslinked equine collagen samples showed a significantly reduced swelling ratio compared to bovine collagen samples. The amino acid compn. of equine collagen revealed a higher amt. of hydroxylysine and lysine. Shrinkage temps. of non-crosslinked samples showed a significant difference between equine (60°) and bovine collagen (57°). Three-factor ANOVA anal. revealed a highly significant effect of collagen type, crosslinking and matrix condition on rupture strength measured by stress-strain anal. The ultrastructure, the crosslinking d. and the strain at rupture between collagen matrixes of both species showed no significant differences. For tissue engineering purposes, the higher enzymic stability, the higher form stability, as well as the lower risk of transmissible disease make the case for considering equine-based collagen. This study also indicates that results obtained for scaffolds based on a certain collagen species may not be transferable to scaffolds based on another, because of the differing physico-chem. properties

Endoscopic vacuum therapy significantly improves clinical outcomes of anastomotic leakages after 2-stage, 3-stage, and transhiatal esophagectomies

Background Anastomotic leakages after esophagectomies continue to constitute significant morbidity and mortality. Intrathoracic anastomoses pose a high risk for mediastinitis, sepsis, and death, if a leak is not addressed timely and appropriately. However, there are no standardized treatment recommendations or algorithms as for how to treat these leakages. Methods The study included all patients at the University Hospital Regensburg, who developed an anastomotic leakage after esophagectomy with gastric pull-up reconstruction from 2007 to 2022. Patients receiving conventional treatment options for an anastomotic leakage (stents, drainage tubes, clips, etc.) were compared to patients receiving endoscopic vacuum-assisted closure (eVAC) therapy as their mainstay of treatment. Treatment failure was defined as cervical esophagostomy formation or death. Results In total, 37 patients developed an anastomotic leakage after esophagectomy with a gastric pull-up reconstruction. Twenty patients were included into the non-eVAC cohort, whereas 17 patients were treated with eVAC. Treatment failure was observed in 50% of patients (n = 10) in the non-eVAC cohort and in 6% of patients (n = 1) in the eVAC cohort (p < 0.05). The 90-day mortality in the non-eVAC cohort was 15% (n = 3) compared to 6% (n = 1) in the eVAC cohort. Cervical esophagostomy formation was required in 40% of cases (n = 8) in the non-eVAC cohort, whereas no patient in the eVAC cohort underwent cervical esophagostomy formation. Conclusion eVAC therapy for leaking esophagogastric anastomoses appears to be superior to other treatment strategies as it significantly reduces morbidity and mortality. Therefore, we suggest eVAC as an essential component in the treatment algorithm for anastomotic leakages following esophagectomies, especially in patients with intrathoracic anastomoses

Scale-Invariant Biomarker Discovery in Urine and Plasma Metabolite Fingerprints

Metabolomics data is typically scaled to a common reference like a constant volume of body fluid, a constant creatinine level, or a constant area under the spectrum. Such scaling of the data, however, may affect the selection of biomarkers and the biological interpretation of results in unforeseen ways. Here, we studied how both the outcome of hypothesis tests for differential metabolite concentration and the screening for multivariate metabolite signatures are affected by the choice of scale. To overcome this problem for metabolite signatures and to establish a scale-invariant biomarker discovery algorithm, we extended linear zero-sum regression to the logistic regression framework and showed in two applications to ¹H NMR-based metabolomics data how this approach overcomes the scaling problem. Logistic zero-sum regression is available as an R package as well as a high-performance computing implementation that can be downloaded at https://github.com/rehbergT/zeroSum