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Publikation Bone regeneration by the osteoconductivity of porous titanium implants manufactured by selective laser melting: A histological and µCT study in the rabbit(Mary Ann Liebert, 2013) de Wild, Michael; Schumacher, Ralf; Kyrill, Maier; Schkommodau, Erik; Thoma, Daniel; Bredell, Marius; Kruse, Astrid; Grätz, Klaus; Weber, FranzThe treatment of large bone defects still poses a major challenge in orthopaedic and cranio-maxillofacial surgery. One possible solution could be the development of personalized porous titanium-based implants that are designed to meet all mechanical needs with a minimum amount of titanium and maximum osteopromotive properties so that it could be combined with growth factor-loaded hydrogels or cell constructs to realize advanced bone tissue engineering strategies. Such implants could prove useful for mandibular reconstruction, spinal fusion, the treatment of extended long bone defects, or to fill in gaps created on autograft harvesting. The aim of this study was to determine the mechanical properties and potential of bone formation of light weight implants generated by selective laser melting (SLM). We mainly focused on osteoconduction, as this is a key feature in bone healing and could serve as a back-up for osteoinduction and cell transplantation strategies. To that end, defined implants were produced by SLM, and their surfaces were left untreated, sandblasted, or sandblasted/acid etched. In vivo bone formation with the different implants was tested throughout calvarial defects in rabbits and compared with untreated defects. Analysis by micro computed tomography (µCT) and histomorphometry revealed that all generatively produced porous Ti structures were well osseointegrated into the surrounding bone. The histomorphometric analysis revealed that bone formation was significantly increased in all implant-treated groups compared with untreated defects and significantly increased in sand blasted implants compared with untreated ones. Bone bridging was significantly increased in sand blasted acid-etched scaffolds. Therefore, scaffolds manufactured by SLM should be surface treated. Bone augmentation beyond the original bone margins was only seen in implant-treated defects, indicating an osteoconductive potential of the implants that could be utilized clinically for bone augmentation purposes. Therefore, designed porous, lightweight structures have potential for bone regeneration and augmentation purposes, especially when complex and patient-specific geometries are essential.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Dynemicin analogs: Syntheses, methods of preparation and use(United States Patent and Trademark Office, 04.01.1994) Smith, Adrian L.; Hwang, Chan-Kou; Wendeborn, Sebastian; Nicolaou, Kyriacos C.; Schreiner, Erwin P.; Stahl, Wilhelm; Dai, Wei-Min; Maligres, Peter E.; Suzuki, ToshioA fused ring system compound is disclosed that contains an epoxide group on one side or the fused rings and an enediyne macrocyclic ring on the other side of the fused rings. The compounds have DNA-cleaving, antimicrobial and tumor growth-inhibiting properties. Chimeric compounds having the fused ring system compound as an aglycone bounded to (i) a sugar moiety as the ogligosaccharide portion or(ii) a monoclonal antibody or antibody combining site portion thereof that immunoreacts with target tumor cells are also disclosed. Compositions containing a compound or a chimer are disclosed, as are methods or preparing a compound.12 - PatentPublikation Enantiomeric dynemicin analogs, preparation and use thereof(World Intellectual Property Organization, 25.11.1993) Smith, Adrian L.; Wendeborn, Sebastian; Nicolaou, Kyriacos; Schreiner, Erwin P.; Dai, Wei-Min; Susuki, ToshioAn enantiomer of a fused ring system compound is disclosed that contains an epoxide group on one side of the fused rings and an enediyne macrocyclic ring on the other side of the fused rings. The enantiomeric compounds have DNA-cleaving, antimicrobial and tumor growth-inhibiting properties that are enhanced over their racemates. Chimeric compounds having the enantiomeric fused ring system compound as an aglycone bonded to (i) a sugar moiety as the oligosaccharide portion or (ii) a monoclonal antibody or antibody combining site portion thereof that immunoreacts with target tumor cells are also disclosed. Compositions containing an enatiomeric compound or an enantiomeric chimer are disclosed, as are methods of preparing an enantiomeric compound.12 - PatentPublikation Environmental chemicals affect circadian rhythms. An underexplored effect influencing health and fitness in animals and humans(Elsevier, 04/2021) Zheng, Xuehan; Zhang, Kun; Zhao, Yanbin; Fent, KarlCircadian rhythms control the life of virtually all organisms. They regulate numerous aspects ranging from cellular processes to reproduction and behavior. Besides the light-dark cycle, there are additional environmental factors that regulate the circadian rhythms in animals as well as humans. Here, we outline the circadian rhythm system and considers zebrafish (Danio rerio) as a representative vertebrate organism. We characterize multiple physiological processes, which are affected by circadian rhythm disrupting compounds (circadian disrupters). We focus on and summarize 40 natural and anthropogenic environmental circadian disrupters in fish. They can be divided into six major categories: steroid hormones, metals, pesticides and biocides, polychlorinated biphenyls, neuroactive drugs and other compounds such as cyanobacterial toxins and bisphenol A. Steroid hormones as well as metals are most studied. Especially for progestins and glucocorticoids, circadian dysregulation was demonstrated in zebrafish on the molecular and physiological level, which comprise mainly behavioral alterations. Our review summarizes the current state of knowledge on circadian disrupters, highlights their risks to fish and identifies knowledge gaps in animals and humans. While most studies focus on transcriptional and behavioral alterations, additional effects and consequences are underexplored. Forthcoming studies should explore, which additional environmental circadian disrupters exist. They should clarify the underlying molecular mechanisms and aim to better understand the consequences for physiological processes.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems: An overview(Taylor & Francis, 16.09.2016) van Hullebusch, Eric D.; Guibaud, Gilles; Simon, Stéphane; Lenz, Markus; Yekta, Sepehr Shakeri; Fermoso, Fernando G.; Jain, Rohan; Duester, Lars; Roussel, Jimmy; Guillon, Emmanuel; Skyllberg, Ulf; Almeida, C. Marisa R.; Pechaud, Yoan; Garuti, Mirco; Frunzo, Luigi; Esposito, Giovanni; Carliell-Marquet, Cynthia; Ortner, Markus; Collins, Gavin01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Organic photovoltaics: Potential fate and effects in the environment(Elsevier, 2012) Zimmermann, Yannick-Serge; Schäffer, Andreas; Hugi, Christoph; Fent, Karl; Corvini, Philippe; Lenz, MarkusIn times of dwindling fossil fuels it is particularly crucial to develop novel “green” technologies in order to cover the increasing worldwide demand for energy. Organic photovoltaic solar cells (OPVs) are promising as a renewable energy source due to low energy requirement for production, low resource extraction, and no emission of greenhouse gasses during use. In contrast to silicium-based solar cells, OPVs offer the advantages of light-weight, semi-transparency and mechanical flexibility. As to a possible forthcoming large-scale production, the environmental impact of such OPVs should be assessed and compared to currently best available technologies. For the first time, this review compiles the existing knowledge and identifies gaps regarding the environmental impact of such OPVs in a systematic manner. In this regard, we discuss the components of a typical OPV layer by layer. We discuss the probability of enhanced release of OPV-borne components into the environment during use-phase (e.g. UV- and biodegradation) and end-of-life phase (e.g. incineration and waste disposal). For this purpose, we compiled available data on bioavailability, bioaccumulation, biodegradation, and ecotoxicity. Whereas considerable research has already been carried out concerning the ecotoxicity of certain OPV components (e.g. nanoparticles and fullerenes), others have not been investigated at all so far. In conclusion, there is a general lack of information about fate, behavior as well as potential ecotoxicity of most of the main OPV components and their degradation/transformation products. So far, there is no evidence for a worrying threat coming from OPVs, but since at present, no policy and procedures regarding recycling of OPVs are in action, in particular improper disposal upon end-of-life might result in an adverse effect of OPVs in the environment when applied in large-scale.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Production of superparamagnetic nanobiocatalysts for green chemistry applications(Springer, 23.04.2016) Gasser, Christoph; Ammann, Erik; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, PhilippeImmobilization of enzymes on solid supports is a convenient method for increasing enzymatic stability and enabling enzyme reuse. In the present work, a sorption-assisted surface conjugation method was developed and optimized to immobilize enzymes on the surface of superparamagnetic nanoparticles. An oxidative enzyme, i.e., laccase from Trametes versicolor was used as model enzyme. The immobilization method consists of the production of superparamagnetic nanoparticles by co-precipitation of FeCl2 and FeCl3. Subsequently, the particle surface is modified with an organosilane containing an amino group. Next, the enzymes are adsorbed on the particle surface before a cross-linking agent, i.e., glutaraldehyde is added which links the amino groups on the particle surface with the amino groups of the enzymes and leads to internal cross-linking of the enzymes as well. The method was optimized using response surface methodology regarding optimal enzyme and glutaraldehyde amounts, pH, and reaction times. Results allowed formulation of biocatalysts having high specific enzymatic activity and improved stability. The biocatalysts showed considerably higher stability compared with the dissolved enzymes over a pH range from 3 to 9 and in the presence of several chemical denaturants. To demonstrate the reusability of the immobilized enzymes, they were applied as catalysts for the production of a phenoxazinone dye. Virtually, 100 % of the precursor was transformed to the dye in each of the ten conducted reaction cycles while on average 84.5 % of the enzymatic activity present at the beginning of a reaction cycle was retained after each cycle highlighting the considerable potential of superparamagnetic biocatalysts for application in industrial processes.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Sulfur amino acid status controls selenium methylation in pseudomonas tolaasii. Identification of a novel metabolite from promiscuous enzyme reactions(American Society for Microbiology, 26.05.2021) Liu, Ying; Hedwig, Sebastian; Schäffer, Andreas; Lenz, Markus; Martinez, MathieuSelenium (Se) deficiency affects many millions of people worldwide, and the volatilization of methylated Se species to the atmosphere may prevent Se from entering the food chain. Despite the extent of Se deficiency, little is known about fluxes in volatile Se species and their temporal and spatial variation in the environment, giving rise to uncertainty in atmospheric transport models. To systematically determine fluxes, one can rely on laboratory microcosm experiments to quantify Se volatilization in different conditions. Here, it is demonstrated that the sulfur (S) status of bacteria crucially determines the amount of Se volatilized. Solid-phase microextraction gas chromatography mass spectrometry showed that Pseudomonas tolaasii efficiently and rapidly (92% in 18 h) volatilized Se to dimethyl diselenide and dimethyl selenyl sulfide through promiscuous enzymatic reactions with the S metabolism. However, when the cells were supplemented with cystine (but not methionine), a major proportion of the Se (∼48%) was channeled to thus-far-unknown, nonvolatile Se compounds at the expense of the previously formed dimethyl diselenide and dimethyl selenyl sulfide (accounting for <4% of total Se). Ion chromatography and solid-phase extraction were used to isolate unknowns, and electrospray ionization ion trap mass spectrometry, electrospray ionization quadrupole time-of-flight mass spectrometry, and microprobe nuclear magnetic resonance spectrometry were used to identify the major unknown as a novel Se metabolite, 2-hydroxy-3-(methylselanyl)propanoic acid. Environmental S concentrations often exceed Se concentrations by orders of magnitude. This suggests that in fact S status may be a major control of selenium fluxes to the atmosphere. IMPORTANCE Volatilization from soil to the atmosphere is a major driver for Se deficiency. “Bottom-up” models for atmospheric Se transport are based on laboratory experiments quantifying volatile Se compounds. The high Se and low S concentrations in such studies poorly represent the environment. Here, we show that S amino acid status has in fact a decisive effect on the production of volatile Se species in Pseudomonas tolaasii. When the strain was supplemented with S amino acids, a major proportion of the Se was channeled to thus-far-unknown, nonvolatile Se compounds at the expense of volatile compounds. This hierarchical control of the microbial S amino acid status on Se cycling has been thus far neglected. Understanding these interactions—if they occur in the environment—will help to improve atmospheric Se models and thus predict drivers of Se deficiency.01A - Beitrag in wissenschaftlicher Zeitschrift
