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The aims of this study were to quantify the key mineralization processes and the resulting nutrient release potentials of different sediment types, their ranges of extent and dependency on varying environmental conditions such as seasonal variations or shifts in oxygen availability. Benthic phosphate fluxes and flux potentials were of particular interest as P is an essential nutrient for algal growth in marine systems and phosphate is often limiting primary production, hence strongly promotes the production of new biomass. A major P source in marine environments are mineralization products of early diagenetic processes.
To gain insight into the pathways of organic matter mineralization and subsequent secondary reactions, key reactants in the solid and the dissolved phase were considered in typical sediments of the Baltic Sea and the Black Sea. Seven study sites in the German Baltic Sea region, representative of the major depositional environments, including coarse and fine grained sediments, both rich or poor in organic carbon, were intensively studied. The investigations were conducted on a seasonal basis during ten ship-based expeditions between July 2013 and March 2016, covering spring- and autumn algal blooms, stagnation periods with bottom water hypoxia and winter dormancy. Hypoxic conditions frequently developed in the bottom waters of the Bay of Mecklenburg, Stoltera and the Arkona Basin sites, shallower stations like the Tromper Wiek, the Oder Bank and the Darss Sill were usually not affected by hypoxia. Increased nutrient concentrations in the bottom waters coincided with oxygen depletion. High salinity dynamics were observed in the bottom waters above the studied sediments, which were due to frequent salt water inflows from the North Sea. Bottom water temperature variability was seasonally conditioned.
The studied sands showed 2-3 orders of magnitude higher permeability values and about one order of magnitude lower organic matter contents compared to the studied muds. Occasionally, strongly increased organic matter contents were observed in the sands, likely induced by downward mixing of plankton bloom derived particles. The organic matter was found to be essentially supplied by marine phytoplankton, indicated by its elemental composition and isotopic signature.
Additionally, an adapted approach of the Keeling plot method was made to characterize the source material of organic matter mineralization. In marine environments, dissolved inorganic carbon concentrations often increase with depth together with an isotopic carbon signature shift to lighter values due to organic matter mineralization. The Keeling plot method was commonly used to determine the isotopic signature of carbon sources for ecosystem respiration. Conventionally, the influence of respiratory depletion of 13CO2 on the isotopic composition of the atmosphere was studied in terrestrial and limnic biogeochemistry. The same approach was applied on organic matter mineralization in sediments and the water column during this study. Mixing of bottom water derived background DIC and DIC released into the environment during organic carbon decomposition was assumed. In a modification of previous approaches, where changes in concentration and δ13C of DIC were followed over time, vertical profiles were analyzed in this study, which represent time-dependent variations superimposed by transport processes . DI13C gradients in the water column of the Black Sea and pore water profiles in the Black Sea and the Baltic Sea were used to estimate the 13C signature of the mineralized organic carbon via Keeling plot analysis. The Black Sea water column revealed a δ13C signature of the organic matter source close to the signature of typical particulate organic matter in the ocean and previously reported values for the Black Sea euphotic zone. In the pore waters of Black Sea sediments (from short and long sediment cores), Keeling plot analysis clearly demonstrates that the released DIC at depth can be derived from different sources. An isotopically very light carbon source (< –60 ‰) was associated with anaerobic oxidation of methane in the Black Sea. Marine organic matter was the principal source for DIC in the deeps of Baltic Sea basins, while the calculated carbon source isotopic signature in sediments of sand flats and bays was shifted to heavier δ13C signatures compared to marine organic matter. These shifts were attributed to potential dissolution of sedimentary carbonates or organic inputs of terrestrial C4 vascular plants like maize and other agricultural plants. The carbon source isotopic composition calculated via Keeling plot analysis correlated well with directly measured δ13C signatures of surface sediments POM.
Organic matter mineralization activity in the southern Baltic Sea sediments was studied via gross sulfate reduction rate analysis and total oxygen uptake measurements in sands and muds. Oxygen penetration depths were less than 4 mm in both, muddy and sandy sediments. Oxygen uptake rates were similar in muds (10.2 mmol m–2 d–1) and sands (10.7 mmol m–2 d–1), while significantly higher rates were measured in the coastal near sites of the Bay of Mecklenburg (about 12 mmol m–2 d–1) than in the deeper Arkona Basin (about 9 mmol m–2 d–1). Substantial sulfate reduction was measured in the muddy (about 4 mmol m–2 d–1) and the sandy (about 1 mmol m–2 d–1) study sites. Highest sulfate reduction rates (4.4 – 5 mmol m–2 d–1) were detected in the muds of the Bay of Mecklenburg during summer, about twice as high as in the Arkona Basin muds. Increased mineralization activity of the coastal near muds of the Bay of Mecklenburg is attributed to enhanced input of fresh organic matter during algal blooms.
About twofold higher oxygen consumption and sulfate reduction rates were measured in summer compared to winter in sandy and muddy sediments.
The studied sites were usually characterized by a typical biogeochemical zonation with oxic, suboxic and sulfidic zones. The concentration profiles in the muds reflected sulfate reduction and secondary redox-reactions, liberating dissolved carbon, nitrogen, phosphorus and hydrogen sulfide into the interstitial waters. Orders of magnitude lower concentrations were detected in the sands, while their top centimeters were mostly irrigated and mineralization products only accumulated below.
A several centimeter thick suboxic zone was sustained by active downward transport of oxidized material in the southern Baltic Sea coastal sediments, presumably mainly through bioturbation. Especially sulfur and iron species were involved in the secondary reactions between the metabolites of early diagenetic processes occurring in the suboxic zone. Partly high temporal variability was observed in the form of vertical migration of the sulfidic zone and a corresponding expansion and shrinking of the suboxic zone. The Arkona Basin site showed the most stable geochemical zonation over time, while the Luebeck Bight site and especially the Mecklenburg Bight site showed striking dynamics. The consequent redox-regime shifts within the surface sediments might promote mineralization of organic matter as higher sulfate reduction rates and higher total oxygen uptake were measured in these more dynamic muds. The vertical shifts of the redox-gradients can largely be explained by temporal and spatial variability of bioturbation activity, but also anthropogenic activities may play a role. Bottom trawling, may be the dominant mixing process at the Mecklenburg Bight site.
In the sands, less reactive iron and manganese contents were available compared to the studied muds, which may be due to frequent irrigation of the top centimeters leading to a loss of pore water reservoirs like dissolved Fe and Mn.
Another mixing process, storm induced sediment resuspension, was suggested to be important for the sediments in the study area. A severe sediment resuspension event at the silty Tromper Wiek site was indicated by steep gradients in pore water concentration and particulate mater content profiles in the top ∼ 5 cm sediments. Carrying out non steady state modeling (Bo Liu, IOW), the successive re-development of the pore water profiles towards a steady-state was simulated and the time span necessary to establish measured pore water profiles after the sediment disturbance event was approximated. In the predicted time span, daily average wind speeds reached an annual high of the category ‘gale’ which was probably sufficient to resuspend and irrigate the surface silt-type sediments.
This study showed that sediment mixing processes have a strong influence on early diagenetic reactions, solute release potentials and actual fluxes from the sediments. Also the sediment mixing via bottom trawl fishing can be regarded as an event-like disturbance. The newly developed approach of non-steady-state modeling of pore water sets (Bo Liu; IOW) can help to answer the question, how long it takes to reach a steady-state after a sediment disturbance event.
The concentration profiles in interstitial waters were used to calculate net transformation rates via the transport-reaction models REC and PROFILE. The calculations revealed net release of H4SiO4 and PO4 within the top 20 cm of the studied muds, while net DIC and NH+4 consumption and sulfate production was clearly evident within the top ∼ 5 cm. Intensive reoxidation of sulfide that was produced via sulfate reduction was also indicated by large deviations between the modeled net sulfate transformation rates and experimentally derived gross sulfate reduction rates. These surface near transformations were probably associated with microbial chemosynthesis.
The studied sands of the southern Baltic Sea were usually characterized by very low pore water gradients, probably due to their frequent irrigation. Accordingly, calculated transformation rates were one to two orders of magnitude lower in the studied sands compared to the muds of the southern Baltic Sea. However, during a situation with a stratified water column, substantial pore water reservoirs with the typical concentration trends were present in the sandy Darss Sill sediments. Integrated production rates of PO4, Mn2+ and H4SiO4 derived from these concentration profiles were in the same order of magnitude as in the muddy Arkona Basin.
Intensive pore water irrigation is also capable to transport fresh organic matter into the sediment as was occasionally indicated by strongly increased surface near TOC in the sands. Considerable gross sulfate reduction rates and total oxygen uptake rates were measured in the sandy Oder Bank sediments, where pore water concentration profiles rather suggested absence of diagenetic processes. The studied sands were, hence, not unreactive substrates but usually rather unable to preserve the mineralization products.
This reflects the often limited significance of pore water evaluations in irrigated sandy sites but also the high mineralization potentials of coastal sands. Early diagenetic processes and the impact of intense benthic-pelagic exchange in such shallow marine environments is still poorly understood, as they were rarely investigated in the past and are methodologically more difficult to investigate.
The Baltic Sea deeps Gotland Deep and Landsort Deep were mainly controlled by sulfate reduction and shallow anaerobic oxidation of methane. Calculated rates of net sulfate reduction and net sulfide production were equivalent, indicating a lack of sulfide re-oxidation reactions. Phosphate liberation rates were low in the surface sediments, but strong linear concentration gradients indicated liberation at depth.
The euxinic Black Sea sediments were purely controlled by sulfate reduction via anaerobic oxidation of methane at the sulfate-methane transition zone in sediment depths of up to several meters. Subsequent diffusive concentration gradients clearly dominated pore water profiles in the surface sediments.
Benthic solute reservoirs of the top 10 cm pore waters were generally higher in the muds than in the sands of the southern Baltic Sea. The smaller reservoirs in the sands were cause by intensive exchange between pore water and bottom water in these permeable sediments. The three studied muddy sites of the southern Baltic Sea showed great dissimilarities with respect to their pore water compositions. Large observed pools of dissolved Fe2+ and PO4 clearly point to reduction of reactive Fe and release of adsorbed P pools. Multi-dimensional scaling analysis showed that seasonal variability played only a minor role for the observed variability of the benthic solute reservoirs. Principal component analysis revealed that the studied sediments can be characterized by essentially two factors based on their pore water reservoirs of the top 10 cm: 1) their mineralization and accumulation efficiency and 2) their secondary reactions in the suboxic zone, reflecting fundamental differences in their sedimentation conditions and mixing processes. While the sands were similar to each other due to their overall low reservoirs, sands, silts and muds mainly differed in their mineralization and accumulation efficiency. Large variability was also observed within the studied muds regarding their predominating redox metabolites. Highest dissimilarities were evident between the neighboring sites Mecklenburg Bight (mostly suboxic) and Luebeck Bight (mostly sulfidic). Therefore, the biogeochemical state in the studied sediments were shown to be mainly controlled by their sediment type and the transport of reactive iron into the sediments. The supply of organic matter to the sea floor controlled the overall mineralization activity, while the sediment permeability determined the accumulation efficiency of the sediment. Mixing of surface sediments together with the complex relation of oxygen, sulfur, iron and phosphorus in the solid and aqueous phase is controlling benthic nutrient fixation/liberation reactions. Salinity variability showed no noticeable effects on early diagenetic processes. During four sampling occasions in the Arkona Basin, bottom water salinity showed strong variability which was also effecting pore water concentration profiles in more than 15 cm depth. However, concentration profiles of typical organic matter mineralization products remained remarkably stable. Also gross sulfate reduction rates seemed to be unaffected by the variable pore water sulfate concentrations.
Nutrient fluxes across the sediment-water interface were obtained by the interpretation of vertical pore water concentration profiles via different models (diffusive fluxes) and via incubation of intact sediment cores (total fluxes). Benthic diffusive fluxes represent potential release of solutes into the water column. They were often strongly associated with the benthic reservoirs, thus fluxes were highest in the muds, considerably lower in the organic-poorer silts, and generally close to zero in the sands. The dissimilarities between diffusive fluxes in the different sediments were mainly controlled by the sediment type. Highest variability was observed within the muds, controlled by their different diagenetic pathways due to different sediment mixing intensities.
In the muddy sediments, diffusive PO4 fluxes were much higher than mineralization of organic matter with the common element ratios of marine organic matter can provide, indicating active recycling of phosphorus within the muds due to recurring adsorption and re-release on reactive iron oxyhydroxide phases. Especially in the strongly mixed Mecklenburg Bight sediments, pore water dissolved PO4 was primarily controlled by the release of adsorbed P. Actual PO4 release into the bottom waters (determined via core incubation experiments) was only measured under extended bottom water oxygen deficiency conditions. The same applied to the redox-sensitive solutes Fe2+, Mn2+ and sulfide.
For the less redox-sensitive solutes, diffusion usually accounted only for a fraction of the total interfacial flux. The proportion of advective to diffusive transport was estimated with different methods. Bioturbation induced sediment mixing was quantified by comparing the diffusive H4SiO4 fluxes derived from pore water modeling with the total fluxes derived from the core incubations. The studied muds showed infauna induced advection proportions of about 35 – 100 %. Only when infauna was absent, diffusion became the dominant transport process across the sediment-water interface. In the studied sands, advection was the dominating transport process, since their generally low surface near reservoirs lead to diffusive fluxes close to zero. However, it remains unclear whether bioturbation or hydrodynamic irrigation are responsible for that. An attempt was made to estimate the effect of hydrodynamic irrigation for a range of reasonable bottom water velocities from the sediment bedform geometry after Neumann et al. (2017). However, resulting potential hydrodynamic irrigation was found to be rather low compared to reported values from the literature and may significantly underestimate actual irrigation of the sandy sediments.
In a new non steady-state multi-element diagenetic modeling approach (Bo Liu, IOW), vertical δ13C pore water profiles were used to estimate the significance of advective transport processes. Mixing processes at the sediment-water interface were expressed as multiple of pure diffusion (ε). By adjusting this mixing coefficient as boundary condition for best fits of predicted to measured pore water profiles, the degree of these mixing processes was estimated. In the Arkona Basin surface sediments, this approach revealed best fits assuming a mixing depth of 3.5 cm with a tenfold higher total mixing degree based on diffusional transport. The calculated mixing depths and intensities were similar to bioturbation depths and rates obtained via traditional methods (Morys, 2016). The novel modeling approach is a promising method to evaluate surface sediment mixing processes.
Increased mineralization activity during productive seasons lead to increased oxygen consumption and therefore frequent bottom water hypoxia. The effects of hypoxic bottom water conditions on the early diagenetic processes in the sediments were studied via prolonged core incubation experiments. Shifts to bottom water oxygen deficiency had various consequences for benthic reservoirs and fluxes. The oxygen consumption decreased during hypoxic incubation phases. Decreased bioturbation activity diminished advective transport so that total fluxes of redox-insensitive solutes (e.g. H4SiO4) were decreased. Reactive iron and manganese oxides act as barrier (“iron curtain”) in the suboxic zone, preventing redox-sensitive solutes from their release into the water column. After a shift to bottom water hypoxia, these reactive oxides are re-dissolved and liberated into the water column. Prolonged incubation experiments suggested that the Mn-oxide reservoirs were depleted first before the Fe-oxides with the adsorptively bound phosphate were liberated.
The release of nutrients (especially phosphorus), dissolved inorganic carbon, and redox- sensitive compounds (e.g. hydrogen sulfide) strongly varied in the different studied environments, covering coastal-near oxic, temporary hypoxic and euxinic conditions.
In environments, where advection through hydrodynamic irrigation or bioturbation do not occur, like in anoxic or euxinic systems, surface-near pore water gradients reflect total solute interfacial fluxes. They depend on the supply of organic matter to the sea floor, the mineralization rates in the sediments and the composition of the overlying bottom water. In the Black Sea, much of the organic matter mineralization was performed already in the water column and not in the sediments, leading to a decreasing export of organic matter to the sediment and increasing concentrations of mineralization products in the bottom water with increasing water depth. Accordingly, benthic fluxes across the sediment-water interface of the deep Black Sea sites were the lowest of the entire study, essentially reflecting the low mineralization rates of AOM in deeper layers. Highest fluxes in the Black Sea were observed at the continental slope at intermediate water depths, but were still lower than in the Baltic Sea deeps.
In contrast, highest DIC fluxes were detected in the oxygen depleted Baltic Sea deeps Gotland Deep and Landsort Deep. These basins are shallow enough that reactive organic matter reaches the sea floor, where it is mineralized via sulfate reduction close to the sediment surface. Strong concentration gradients and therefore high diffusive interfacial fluxes across the sediment-water interface were evident. As bioturbation was absent, these diffusive fluxes were representative for total interfacial fluxes unlike in sediments with additional advective flux components.
In more complex environments, like coastal oxic sediments, inhabited by macrofauna, overflowed by currents and affected by resuspension events, the sediment surface represents an interface between turbulent and calm conditions, high and low concentrations and/or different redox-states. Such gradients are the basis for intensive exchange processes. The surface sediments in the coastal sites of the southern Baltic Sea were characterized by active organic matter mineralization via sulfate reduction and mixing induced secondary reactions taking place in the suboxic zone. This included the removal of dissolved sulfide due to iron oxide reduction with simultaneous liberation of PO4 into the interstitial waters. High surface near P reservoirs existed due to internal P cycling within the sediments, which was in turn driven by continuous re-oxidation of the reduced iron by downwards transported oxygen. These reservoirs were only actually released into the water column during bottom water oxygen deficiency situations, when the iron re-oxidation was inhibited.
This also applies for sediments of the Gulf of Finland and the deeper Baltic Sea basins Bornholm Basin and Gdanks basin, where temporary hypoxic conditions are responsible for recurrent benthic phosphate release.
The widespread occurring phosphate adsorption on sedimentary solid iron phases is a much debated ecosystem service of marine sediments. As discussed in this work, the sedimentary P liberation rates and pools of readily bio-available dissolved phosphate can be substantial in Baltic Sea muddy sediments. Actual phosphate fluxes across the sediment-water interface, though, are relatively small because phosphate is scavenged by adsorption on iron oxyhydroxides that are usually an integral part of coastal marine sediments if overlain by oxic bottom waters. Although muddy sediments often show only an oxic layer of only few millimeters thickness, adsorption capacities of iron oxyhydroxides are large enough to substantially retain P from being liberated into the water column. Falling under reducing conditions, iron oxyhydroxides are re-dissolved, liberating high amounts of PO4 into the surrounding waters. While permanently oxic sediments will preserve adsorbed P, permanently anoxic sediments steadily release mineralized P into the water column. However, sedimentary environments of oscillating redox conditions are predestined for high, burst-like benthic P fluxes. Especially in a quasi isolated environment like the Baltic Sea, with high nutrient inputs but only few sinks, these internal recycling processes promote eutrophication in the long-term. Further expanding hypoxia and anoxia in the Baltic Sea with a subsequent loss of benthic fauna and altered nutrient dynamics in the surface sediments may be the consequence.
Introduction: Antiseptics are used for the prophylaxis of infections of acute wounds and for the treatment of critically colonized chronic wounds as well as localized infections of acute and chronic wounds. If an antiseptic with too much tissue toxicity and/or too little efficacy is used, the wound healing can be delayed.
Objective: The aim was to compare the irritation potency of frequently used wound antiseptics by using the hen's egg test on the chorioallantoic membrane (HET-CAM). Additionally, the influence of antiphlogistic active additives which might increase the tolerability was examined. To allow a more extensive comparison, antiseptics classified as obsolete such as hydrogen peroxide, creams on PVP- iodine base, silver sulfadiazine, chlorhexidine and nitrofural as well as the non-antiseptic wound treatment agents dexpanthenol and hemoglobin spray were also examined.
Method: The HET-CAM was used as a semi-in-vivo method to test the tolerability of wound antiseptics to tissues by observing the reactions that occur in the blood vessels of the highly vascularized CAM such as hemorrhage, lysis and coagulation. The irritation score (IS) was calculated and differentiated in 4 ranges according to Spielmann (1991).
Results: The vascular injuries of the CAM were considered as an indirect indicator of the tolerability. It is accepted that agents with no or low irritation potential on the CAM are to be preferred in the clinical practice if they are clinically effective.
Severe CAM reaction was observed after short-term application of octenidine based wound gel (active ingredient octenidine 0.05%) (IS: 10.3) and chlorhexidine digluconate 0.5% solution (IS: 9.5). Moderate reaction was observed for the combination of octenidine 0.05% in aqueous solution with panthenol 1.34% and allantoin 0.2% (IS: 8.7), hydrogen peroxide 1.5% in aqueous solution (IS: 6.1) and hydrogen peroxide 0.5% solution (IS: 5.5). Slight reaction was observed for hydrogen peroxide 1.5% solution in combination with sodium thiocyanate 0.698% (IS: 2.6), sodium thiocyanate 0.698% solution (IS: 2.1) and Dermacyn® (active ingredient NaOCl/HOCl each 0.004) (IS: 1.2). Polihexanide 0.04% in Ringer solution (IS: 0.9), Polihexanide 0.05% in Lipofundin, Granulox® (active agent hemoglobin 10%) (IS: 0) and dexpanthenol 5% solution (IS: 0) showed no reaction. In the long-term observation (24 hours after application), Dermacyn® showed the best results (59% of irritation remained alive after 24 hours). The addition of dexpanthenol and allantoin reduced the irritability only slightly, whereas the decrease of IS of hydrogen peroxide by addition of sodium thiocyanate was almost significant (p 0.0596).
Conclusion: It is suggested that agents with no or low irritation potential on the CAM are to be preferred in the clinical practice if they are clinically effective. It is suggested that further in vivo and in vitro studies are to be undertaken with these agents.
Solely regarding local tolerability, polihexanide and hypochlorite are the antiseptic agents of choice of the tested preparations. The wound oxygenizer hemoglobin spray is tolerated without irritation as well as the negative control 0.9% NaCl solution. Because of their other disadvantages in conjunction with their irritability, the outdated cream formulations on basis of silver sulfadiazine, PVP- iodine, chlorhexidine and nitrofural cannot be recommended for wound antisepsis.
Since its introduction in 2006, the NOD/scid mouse model has greatly contributed to the understanding of the pathomechanisms of antibody-mediated thrombocytopenia. This progress has however been hampered by inter-laboratory differences. With this work, we make several suggestions to minimise these differences:
We suggest that human platelets (blood group 0) be injected into the mice (age- and sex-matched, 8-16 weeks) via the tail vein. For antibody injection, scientists may choose between intraperitoneal and tail vein injection, each of which has strengths and drawbacks. In case of low antibody titer or low avidity antibodies, preincubation of the platelets with the patient serum prior to injection promotes platelet elimination where standard protocols fail. For subsequent sample preparation, we found that newly-launched ready-to-use kits present a good alternative to classical density gradient centrifugation by reducing man-hours and turnover time without affecting the quality of flow cytometry analysis.
In a second part, we used the revised mouse model to study anti-CD36 mediated thrombocytopenia in vivo. Anti-CD36 antibodies have been suggested as frequent case for FNAIT in Asia. The mechanisms behind this remain partly unclear. After injecting anti-CD36 monoclonal antibody or anti-CD36 patient immunoglobulin into the system, circulating human platelets were rapidly cleared. Interestingly, the polyclonal patient immunoglobulins used were not uniform in their anti-platelet reactivity. On further examination, we found that the anti-CD36 antibodies induce platelet activation and aggregation, which we were able to inhibit by the addition of an Fcγ-receptor blocking agent. This suggests a possible role for Fcγ-receptor in the activation and elimination process.
As our results from the experiments on the role of complement in the elimination process are however ambiguous, further studies are needed. The clinical relevance of anti-CD36 antibody-mediated platelet activation and aggregation for the high abortion rates in affected women has yet to be evaluated.
Psychological health is a result of the effective interplay between explicit and implicit attempts to regulate ones’ emotions (Koole & Rothermund, 2011). Emotion regulation refers to processes that influence the intensity, the duration and the type of emotion experienced (Gross & Thompson, 2007). While explicit emotion regulation comprises effortful mental processes, implicit emotion regulation refers to processes that require no monitoring and terminate automatically (Gyurak, Gross, & Etkin, 2011).
In the present thesis, explicit and implicit strategies to regulate emotions were investigated. In Study 1, a well-established paradigm (Gross & Levenson, 1993) was adapted to examine the up- and down-regulation of positive and negative emotions using two different explicit emotion regulation strategies. To infer on the neurobiological correlates, blood oxygen level dependent (BOLD) brain activity was recorded using functional magnetic resonance tomography. Furthermore, as a trait marker for the individual ability to regulate emotions, heart rate variability (HRV) was acquired during rest. In Study 2, implicit emotion regulation was examined. Therefore, a well-established fear extinction paradigm was compared to a novel approach based on the integration of new information during reconsolidation (Schiller et al., 2010). Autonomic arousal was measured via the skin conductance response during fear acquisition, fear extinction and after fear reinstatement. In Study 3, two dysfunctional emotion regulation strategies —worrying and rumination— were investigated. Excessive worrying and rumination are pathogenic characteristics of psychological disorders. Behavioral, autonomic and BOLD activity was recorded during worried and ruminative thinking as well as during neutral thinking.
The results showed that explicit emotion regulation was associated with modulated BOLD activity in the amygdala according to the regulation direction independent of the applied strategy and the valence of the emotion. In addition, increased dorsolateral prefrontal cortex (dlPFC) activity was observed during regulation compared to passively viewing emotional pictures. The findings are in line with previous research (Eippert etal., 2007; Kim &Hamann, 2007; Ochsner etal., 2004) and support the key role of the dlPFC during the explicit regulation of emotions. Similarly, implicit emotion regulation was associated with a decreased autonomic fear response, which was sustained after fear extinction during reconsolidation. The findings underscore the notion, that this novel technique might alter the initial fear memory resulting in a permanently diminished fear response (Nader, Schafe, & LeDoux, 2000; Schiller et al., 2010). Dysfunctional emotion regulation was associated with increased autonomic activity and fear potentiated startle (during worry) as well as increased BOLD activity in the insula (during worry and rumination) and increased BOLD activity in the amygdala (during rumination). In addition, neural activity in brain areas associated with the default mode network was observed. These findings stress the preserved negative emotional activity and the self-referential nature of the examined dysfunctional strategies. The results of all three studies are integrated into a neuro-biological model of emotion regulation focusing on the interplay between subcortical and prefrontal brain areas.
Aiming at the goal of individualized medicine, this dissertation develops a generic methodology to individualize risk factors and phenotypes via metabolomic data from the urine. As metabolomic data can be seen as a holistic representation of the metabolism of an organism at certain time point, metabolomic data contain not only information about current life-style factors like diet and smoking but also about latent genetic traits. Utilizing this integrative attribute, the dissertation delivers a metric for biological age (the metabolic age score) which was shown to be informative beyond chronological age in three independent samples. It was associated with a broad range of age-related comorbidities in two large population-based cohorts, predicted independently of classical risk factors mortality and, moreover, it predicted weight loss subsequently to bariatric surgery in a small sample of heavily obese individuals.
Subsequently to this work, the dissertation built a definitional framework justifying the procedure underlying the metabolic age score, delivering a general framework for the construction of individualized phenotypes and thereby an operationalization of individualization in statistical terms. Conceptualizing individualization of the process of differentiation of individuals showing the same phenotype despite different underlying biological traits, it was shown formally that the prediction error of a statistical model approximating a phenotype is always informative about the underlying biology beyond the phenotype if the predictors fulfill certain statistical requirements. Thus, the prediction error facilitates the meaningful differentiation of individuals showing the same phenotype. The definitional framework presented here is not restricted to any kind of data and is therefore applicable to a broad range of medical research questions.
However, when utilizing metabolomic data, technical factors, data-preprocessing, pre-analytic features introduce unwanted variance into the statistical modeling. Thus, it is unclear whether predictive models like the metabolic age score are stable enough for clinical application. The third part of this doctoral thesis provided two statistical criteria to decide which normalization method to remove the dilution variance from urinary metabolome data performs best in terms of erroneous variance introduced by the different methods, aiding the minimization of biological irrelevant variance in metabolomic analyses.
In conclusion, this doctoral thesis developed a general, applicable, definitional framework for the construction of individualized phenotypes and demonstrated the value of the methodology for clinical phenotypes on metabolomic data, improving on the way the statistical treatment of urinary data regarding the dilution correction.
The intracellular life cycle of the human immunodeficiency virus (HIV) is modelled using ordinary differential equations (ODEs). Model parameters are obtained from the literature or fitted to experimental data using parameter estimation procedures. Key steps in the life cycle are inhibited singly and in combination to show the effects on viral replication. The results validate the success of highly active antiretroviral therapy (HAART), and in addition DNA nuclear import is identified as a novel influential therapeutic target.
Foot-and-mouth disease virus (FMDV) is a positive-sense RNA virus of the family Picornaviridae that comprises of seven serotypes and is distinguished by a high contagiosity with the ability of rapid spread. Strategies for abatement and control are based on an early detection, quick initiation of retaliatory actions and mass vaccinations. Therefore, aim of the study was the development of a fast and easy method for genome sequencing as well as an investigation into the causes, why some cell lines that are mainly used for vaccine production, are resistant towards FMDV infection. Finally, adaptive sequence changes in different cell culture systems and associated effects on particle stability and immunogenicity were examined.
In case of an outbreak it is of major importance to detect and rapidly characterize the circulating virus isolate to choose an appropriate vaccine to minimize the viral spread. In addition, comprehensive genome analysis of the outbreak strain provides information about the origin of the virus and allows molecular epidemiology. A universal primer set, covering most parts of the open reading frame of the viral genome, was developed to perform quick sequence analyses, independently of the viral serotype (Paper I). Especially in endemic regions, vaccination of susceptible animal species is the main action to combat foot-and-mouth disease (FMD) in an acute outbreak situation as well as a preventive measure. Reasons, why some baby hamster kidney (BHK) cell lines are resistant towards an infection with FMDV, were examined in a second study that narrowed down the cause for this phenomenon to an impaired attachment of the virus to the cell surface. Furthermore, an alternative approach could be developed to successfully adapt the virus to the resistant vaccine-production cell line by using a FMDV-sensitive “wet-nurse” cell line (Paper II). Adaptive changes in the capsid-coding region of the viral genome caused through cultivation and passaging of the virus in different BHK cell systems were the topics of the third study. It was shown that capsid alterations are rather serotype-specific and dependent on the cell line used than influenced by the cell media. Viral titers and neutralization profiles of the adapted isolates were not affected compared to the original viruses (Paper III).
Overall, this work expanded our knowledge on the control and eradication of FMD and will support the global effort to combat the disease.
The “East German National Park Programme” of 1989/1990 was considered a coup de main, resulting in the immediate protection of 4.5% of the GDR’s territory. The authors of this programme later described the approach and its success as “using a window of opportunity during the transition phase of state and nation.” This leads to the question whether a state’s transformation period constitutes a preferred time frame and momentum for spatial conservation success.
Conservation efforts in Azerbaijan showed a similar success as the East German National Park Programme. In a country with the highest biodiversity in Europe, increasing the share of protected land from 5.0 % in 2001 to 10.3% in 2015 constitutes a remarkable achievement. Thus, the country became an interesting case study regarding the question whether “hot moments for conservation” exist in times of political and governmental changes, and if spatial success in nature conservation can be linked to political transformation. This thesis attempts to identify how the protected area (PA) network in Azerbaijan could be expanded by 100%, what achievements were made, and what conditions still need to be met for the quantitative and qualitative improvement of the PA network. To this end, I consider this increase under landscape-ecological, historical and institutional aspects. The local culture and political pre-sets in the country present additional issues for analysing the past 25 years of nature conservation in Azerbaijan.
Lead-cluster investigations
(2017)
In this thesis, investigations on lead clusters stored in a Penning trap are presented. The measurements are performed at the ClusterTrap setup at the Institute of Physics of the University of Greifswald. A Penning trap with a superconducting magnet (B=12 Tesla) makes up the central part of the experiment. In this trap, singly positively or negatively charged lead clusters (a group of lead atoms) are stored, their amplitudes of motion are cooled, and a specific cluster size is selected. Thus, clusters of only a single size are prepared for experimental investigation. After interactions with electrons and/or photons, the trap content is extracted and analyzed by time-of-flight mass spectrometry.
In the first experiment, the size-selected clusters are excited by a frequency-doubled Nd:YAG laser, which leads to fragmentation processes. The preferred fragmentation pathway, which is observed to be break-off of a seven-atom neutral cluster is unusual for metal clusters, which typically evaporate monomers. Furthermore, the already known magic cluster sizes are observed.
In a subsequent experiment, positively charged lead clusters with 31 atoms are irradiated with laser light and fragmentation processes are time resolved investigated. The assumption that lead clusters fragment by break-off of neutral heptamers is confirmed.
In the following experiment, an electron beam is guided through the Penning trap to ionize pulsed-in argon atoms. While the positive argon ions leave the trap, the secondary electrons are trapped together with the selected lead clusters. This allows the electrons to attach to the singly charged lead clusters, which leads to multiply negatively charged lead clusters. The relative abundance of multiply-charged clusters is measured with respect to the cluster size, from which the appearance sizes of di- and trianions can be calculated. In addition to the attachment of electrons, fragmentation products similar to those of the photoexcitation measurements are observed. Furthermore, the cluster sizes 10 and 12 are observed regardless of the investigated precursor size, together with clusters of the precursor size reduced by 10 and 12. This is a first hint for a fission process of doubly negatively charged lead clusters into two singly charged products. In a following measurement, doubly charged lead clusters are produced and photoexcited. The observed abundance spectra confirm this assumption.
The thyroid as the largest endocrine gland mainly produces and secretes the thyroid hormones (TH): 3,3’,5-triiodo-L-thyronine (T3) and its pro-hormone L-thyroxine (T4). Besides the impact on growth, normal development, bone marrow structure, the cardiovascular system, body weight and thermogenesis, TH play a vivid role in many metabolic regulatory mechanisms in almost all tissues. Thyroid diseases are relatively prevalent and cause, due to the resulting TH imbalances, a broad spectrum of effects. Many of them manifest in pathologically increased or decreased TH levels defined as hyperthyroidism or hypothyroidism, respectively. Routinely, determination of the thyroid state is based on the assessment of the classical markers TSH and free T4. However, this practice has several drawbacks. Moreover, elucidation of the pleiotropic effects of TH on multiple molecular pathways is mostly based on cell culture, tissue and rodent models. Analysis of animal biofluids like serum and urine using metabolomics approaches demonstrated the extensive impact of TH on other body compartments. In contrast, proteome profiling has not been exploited for the comprehensive characterization of the general metabolic effects of TH. Plasma as a large and diverse compartment of the human proteome provides a great opportunity to identify novel protein markers of thyroid function as well as to characterize metabolic effects of TH in humans.
Therefore, a study of experimental thyrotoxicosis was performed with 16 male volunteers treated with 0.25 mg/d levothyroxine (L-T4) for 8 weeks to induce a hyperthyroid state. Plasma samples were collected before the L-T4 application started, two times during the treatment and additionally two times after withdrawal. Proteome analysis revealed remarkable alterations including increased levels of two known proteins known to correlate with TH levels (sex hormone-binding globulin and cystatin C). The correlation with free T4 levels revealed 76 out of 437 detected proteins with a Pearson correlation coefficient of r ≥ |0.9|. One prominent signature included 10 coagulation cascade proteins exhibiting significantly increased plasma levels during thyrotoxicosis, thereby revealing a trend towards a hypercoagulative state in hyperthyroidism. To overcome the statistical drawbacks of the Pearson correlation analysis, additionally a mixed-effect linear regression model using serum free T4 concentrations as exposure and protein abundances as outcome while controlling for age, BMI, and batch was implemented. Application of this model resulted in the detection of 63 proteins with significant associations to free T4 levels. Besides the already mentioned augmented coagulation, a significant drop in the amounts of three apolipoproteins (ApoD, ApoB-100 and ApoC3) was observed. Furthermore, an increased abundance of proteins assigned to the complement system was detected.
Experimental studies in humans were complemented by corresponding analyses in murine models. In the current work, plasma samples of two murine studies including male C57BL/6 wildtype mice were analyzed to elucidate the impact of thyroid dysfunction on the plasma proteome. The first study was similarly designed as the human model of experimentally induced thyrotoxicosis and assigned the animals to three groups: a control group, a T4 treatment group, and a T4 recovery group, whereupon the latter first received T4 followed by a subsequent TH normalization period. A high proportion of plasma proteins exhibited significantly different protein levels during T4 application (n = 120), where 90 of these also showed a corresponding reverse trend after T4 withdrawal (T4 recovery vs. T4), thereby displaying transient alterations. The molecular pattern of hyperthyroidism in the murine model indicated, as in the human study, a pronounced decrease in apolipoproteins. However, in clear contrast to the human data, the levels of proteins related to the coagulation cascade and complement system were also transiently decreased in mice, while being increased in humans.
The second murine analysis focused on the impact of hyper- and hypothyroidism caused by T3 or T4 treatment and MMI/KClO4 application, respectively. In general, compared to the first murine study less clear alterations of protein levels were detected. Proteins related to the complement system revealed fewer changes in the T3 group and only marginal changes after T4 induction. Unexpectedly, the MMI/KClO4-induced hypothyroidism caused a reduction of the levels of several proteins assigned to the complement system, although different components and factors were affected.
Generally, rodent studies partially provided a divergent picture of TH action as compared to human studies. However, in spite of inconsistent results in studies regarding the effects of TH that are possibly due to species-specific differences, an important role of TH on several metabolic and other pathways, e.g. in the process of blood coagulation and apolipoprotein regulation, is evident. The results from both murine and human studies presented here provide novel insights into changes in the plasma proteome in the context of thyroid diseases which might contribute to a better understanding of TH action on metabolism and other pathways.