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"Müller, Michelle"
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Sea Bass Primary Cultures versus RTgill-W1 Cell Line: Influence of Cell Model on the Sensitivity to Nanoparticles
2021
Determination of acute toxicity to vertebrates in aquatic environments is mainly performed following OECD test guideline 203, requiring the use of a large number of fish and with mortality as endpoint. This test is also used to determine toxicity of nanomaterials in aquatic environments. Since a replacement method for animal testing in nanotoxicity studies is desirable, the feasibility of fish primary cultures or cell lines as a model for nanotoxicity screenings is investigated here. Dicentrarchus labrax primary cultures and RTgill-W1 cell line were exposed to several concentrations (0.1 to 200 ug/mL) of different nanoparticles (TiO2, polystyrene and silver), and cytotoxicity, metabolic activity and reactive oxygen species formation were investigated after 24 and 48 h of exposure. Protein corona as amount of protein bound, as well as the influence of surface modification (-COOH, -NH2), exposure media (Leibovitz’s L15 or seawater), weathering and cell type were the experimental variables included to test their influence on the results of the assays. Data from all scenarios was split based on the significance each experimental variable had in the result of the cytotoxicity tests, in an exploratory approach that allows for better understanding of the determining factors affecting toxicity. Data shows that more variables significantly influenced the outcome of toxicity tests when the primary cultures were exposed to the different nanoparticles. Toxicity tests performed in RTgill-W1 were influenced only by exposure time and nanoparticle concentration. The whole data set was integrated in a biological response index to show the overall impact of nanoparticle exposures.
Journal Article
Field Investigation on Hydroabrasion in High-Speed Sediment-Laden Flows at Sediment Bypass Tunnels
by
Albayrak, Ismail
,
Müller-Hagmann, Michelle
,
Boes, Robert M.
in
Analysis
,
Concrete
,
Investigations
2020
Wear due to sediment particles in fluid flows, also termed ‘hydroabrasion’ or simply ‘abrasion’, is an omnipresent issue at hydraulic structures as well as in bedrock rivers. However, interactions between flow field, particle motion, channel topography, material properties and abrasion have rarely been investigated on a prototype scale, leaving many open questions as to their quantitative interrelations. Therefore, we investigated hydroabrasion in a multi-year field study at two Swiss Sediment Bypass Tunnels (SBTs). Abrasion depths of various invert materials, hydraulics and sediment transport conditions were determined and used to compute the abrasion coefficients kv of different abrasion models for high-strength concrete and granite. The results reveal that these models are useful to estimate spatially averaged abrasion rates. The kv‑value is about one order of magnitude higher for granite than for high-strength concrete, hence, using material-specific abrasion coefficients enhances the prediction accuracy. Three-dimensional flow structures, i.e., secondary currents occurring both, in the straight and curved sections of the tunnels cause incision channels, while also longitudinally undulating abrasion patterns were observed. Furthermore, hydroabrasion concentrated along joints and protruding edges. The maximum abrasion depths were roughly twice the mean abrasion depths, irrespective of hydraulics, sediment transport conditions and invert material.
Journal Article
Moment or movement – the heterogeneous impact of the Black Lives Matter movement on personal and societal charitable crowdfunding campaigns
by
Müller, Michelle
,
Müller, Stefanie
,
Seutter, Janina
in
Activism
,
Antidiscrimination
,
Black Lives Matter movement
2024
PurposeWhenever social injustice tackled by social movements receives heightened media attention, charitable crowdfunding platforms offer an opportunity to proactively advocate for equality by donating money to affected people. This research examines how the Black Lives Matter movement and the associated social protest cycle after the death of George Floyd have influenced donation behavior for campaigns with a personal goal and those with a societal goal supporting the black community.Design/methodology/approachThis paper follows a quantitative research approach by applying a quasi-experimental research design on a GoFundMe dataset. In total, 67,905 campaigns and 1,362,499 individual donations were analyzed.FindingsWe uncover a rise in donations for campaigns supporting the black community, which lasts substantially longer for campaigns with a societal than with a personal funding goal. Informed by construal level theory, we attribute this heterogeneity to changes in the level of abstractness of the problems that social movements aim to tackle.Originality/valueThis research advances the knowledge of individual donation behavior in charitable crowdfunding. Our results highlight the important role that charitable crowdfunding campaigns play in promoting social justice and anti-discrimination as part of social protest cycles.
Journal Article
Setting the stage for a flourishing cultural data ecosystem: A spotlight on business models of cultural event platforms
by
Müller, Michelle
,
Althaus, Maike
,
Vorbohle, Christian
in
Archetypes
,
Business
,
Business and Management
2025
Data ecosystems can generate valuable business opportunities, but research on their emergence within specific industries is limited. The cultural event industry is characterized by a multifaceted cultural landscape and a fragmented and heterogeneous market of cultural event platforms. The emerging German cultural data ecosystem, envisioned to share event data in a data space, could foster data-driven innovation and enhance value creation in the cultural event industry. Yet, following the ecosystem-as-structure view, the platforms’ willingness to participate in the cultural data ecosystem depends on whether their business model aligns with at least one of the focal value propositions of the cultural data ecosystem. In this paper, we develop a taxonomy of cultural event platform business models, and derive six archetypes. Additionally, we interview industry representatives of these archetypes to shed light on the benefits and obstacles when participating in the cultural data ecosystem, and to identify potential focal value propositions, corresponding actor roles, and activities. Our work contributes to the discussion on taxonomies of data-sharing business models and the emergence of data ecosystems in the cultural event industry.
Journal Article
Accuracy of the Interpretation of Chest Radiographs for the Diagnosis of Paediatric Pneumonia
by
Muller, Michelle
,
Spencer, David A.
,
Hampton, Fiona
in
Accuracy
,
Adolescent
,
Bacterial infections
2014
World Health Organization (WHO) radiological classification remains an important entry criterion in epidemiological studies of pneumonia in children. We report inter-observer variability in the interpretation of 169 chest radiographs in children suspected of having pneumonia.
An 18-month prospective aetiological study of pneumonia was undertaken in Northern England. Chest radiographs were performed on eligible children aged ≤16 years with clinical features of pneumonia. The initial radiology report was compared with a subsequent assessment by a consultant cardiothoracic radiologist. Chest radiographic changes were categorised according to the WHO classification.
There was significant disagreement (22%) between the first and second reports (kappa = 0.70, P<0.001), notably in those aged <5 years (26%, kappa = 0.66, P<0.001). The most frequent sources of disagreement were the reporting of patchy and perihilar changes.
This substantial inter-observer variability highlights the need for experts from different countries to create a consensus to review the radiological definition of pneumonia in children.
Journal Article
Measurement report: Exploring the variations in ambient BTEX in urban Europe and their environmental health implications
2025
BTEX (benzene, toluene, ethylbenzene, and m-xylene,p-xylene, and o-xylene) are significant urban air pollutants. This study examines BTEX variability across 7 European countries using data from 22 monitoring sites in different urban settings (urban background, traffic, industry, and suburban background). Results indicate that the relative abundance of BTEX in urban areas follows the order toluene > benzene > m,p-xylene > o-xylene > ethylbenzene, with median mixing ratios of 266 ± 152, 163 ± 74, 129 ± 88, 53 ± 35, and 45 ± 27 ppt during the years 2017–2022, respectively. Seasonal trends show benzene had similar median concentrations across urban background, traffic, and industrial sites, indicating mixed sources. Toluene levels were highest in traffic and industrial areas, highlighting road traffic and industrial emissions. Ethylbenzene and xylenes showed equivalent levels in traffic and industrial areas but were lower in urban backgrounds. Peak BTEX levels occurred during morning and evening rush hours, linked to traffic, heating, and atmospheric stagnation. B/T ratios ranged from 0.29 ± 0.11 to 1.35 ± 0.95, and X/E ratios ranged from 1.75 ± 0.91 to 3.68 ± 0.30, indicating primary pollution from local traffic, followed by solvents, coatings, and biomass burning. Lifetime cancer risk from BTEX exposure was below the definite risk threshold (10−4) but above the permissible risk level (10−6), suggesting moderate risk from benzene and ethylbenzene, particularly in traffic and industrial areas. Additionally, the health index of BTEX at monitoring sites was generally lower than the threshold limit value, suggesting a low non-carcinogenic risk overall. This study offers essential insights into BTEX pollution in urban European environments.
Journal Article
Differences in gait analysis and clinical outcome after dynamic fixation or screw fixation in acute syndesmosis tear: a prospective randomized pilot study
by
Müller, Michelle
,
Tsitlakidis, Stefanos
,
Mick, Paul
in
Adult
,
Ankle
,
Ankle Injuries - physiopathology
2024
Introduction
Acute syndesmosis tears can be treated by static screw or dynamic fixation. Various studies have compared these techniques regarding postoperative outcome. However, to our knowledge, no study has used 3D-instrumented gait analysis (IGA). We hypothesized that a dynamic fixation would perform non-inferior to screw fixation in terms of biomechanical and clinical outcomes.
Materials and methods
Patients were prospectively randomized to both groups. All patients received the same follow-up rehabilitation and consultations (6 and 12 weeks; 6 and 12 months) postoperatively. Standardized questionnaires were used to objectify pain and ankle function. At 6 months follow-up, IGA was conducted additionally to objectify the biomechanical outcome.
Results
Twenty-five patients in the dynamic fixation (DF) group using TightRope® and twenty-five in the screw fixation group (SF) completed gait analysis. The DF group showed significantly higher mean values for maximum moment in the affected ankle joint (DF: 1.40 ± 0.21 Nm, SF: 1.23 ± 0.30 Nm; p = 0.023) and the unaffected ankle joint (DF: 1.52 ± 0.20 Nm, SF: 1.37 ± 0.27 Nm; p = 0.035). The difference between the affected and unaffected ankle joint was significantly higher in the SF group for active plantarflexion (DF: 1.52 ± 0.20°, SF: 1.37 ± 0.27°; p = 0.035). Both dynamic and screw fixation groups exhibited significantly reduced plantarflexion during the push-off and early swing phase, with moments and powers in the ankle joint also significantly impaired.
Conclusions
Our study demonstrated that dynamic fixation has better or similar biomechanical and clinical outcomes compared to screw fixation. Future research should focus on biomechanical differences during gait as well as clinical outcomes in case of earlier weight-bearing after dynamic fixation.
Trial registration number (TRN)
DRKS00013562 Date of Registration: 07/12/2017.
Journal Article
Wrap It! Preventive Antimicrobial Treatment Shows No Negative Effects on Tenocytes and Tendons—A Comprehensive Approach
2023
Although the rate of infection after the reconstruction of a ruptured anterior cruciate ligament (ACL) is low, prophylactic incubation of the graft with vancomycin (Vanco-wrap or vancomycin soaking) is routinely performed. A cytotoxic effect of vancomycin is reported for several cell types, and the prophylactic treatment might prevent infection but harm the tissue and cells. Aim: A comprehensive study was performed to investigate the effect of vancomycin on tendon tissue and isolated tenocytes using cell viability, molecular and mechanical analysis. Material and methods: Rat tendons or isolated tenocytes were incubated in increasing concentrations of vancomycin (0–10 mg/mL) for different times, and cell viability, gene expression, histology and Young’s modulus were analyzed. Results: The clinically used concentration of vancomycin (5 mg/mL for 20 min) had no negative effect on cell viability in the tendons or the isolated tenocytes, while incubation with the toxic control significantly reduced cell viability. Increasing the concentration and prolonging the incubation time had no negative effect on the cells. The expression of Col1a1, Col3a1 and the tenocyte markers mohawk, scleraxis and tenomodulin was not affected by the various vancomycin concentrations. The structural integrity as measured through histological and mechanical testing was not compromised. Conclusion: The results proved the safe application of the Vanco-wrap on tendon tissue. Level of evidence: IV.
Journal Article
Targeting Indoleamine 2,3-Dioxygenase in Cancer Models Using the Novel Small Molecule Inhibitor NTRC 3883-0
by
Sterrenburg, Jan Gerard
,
Massuger, Leon F.
,
van Doornmalen, Antoon M.
in
Animal models
,
Animals
,
Ascites
2021
Indoleamine 2,3-dioxygenase (IDO1) is a key regulator of immune suppression by catalyzing the oxidation of L-tryptophan. IDO1 expression has been related to poor prognosis in several cancers and to resistance to checkpoint immunotherapies. We describe the characterization of a novel small molecule IDO1 inhibitor, NTRC 3883-0, in a panel of biochemical and cell-based assays, and various cancer models. NTRC 3883-0 released the inhibitory effect of IDO1 on CD8-positive T cell proliferation in co-cultures of IDO1-overexpressing cells with healthy donor lymphocytes, demonstrating its immune modulatory activity. In a syngeneic mouse model using IDO1-overexpressing B16F10 melanoma cells, NTRC 3883-0 effectively counteracted the IDO1-induced modulation of L-tryptophan and L-kynurenine levels, demonstrating its in vivo target modulation. Finally, we studied the expression and activity of IDO1 in primary cell cultures established from the malignant ascites of ovarian cancer patients. In these cultures, IDO1 expression was induced upon stimulation with IFNγ, and its activity could be inhibited by NTRC 3883-0. Based on these results, we propose the use of ascites cell-based functional assays for future patient stratification. Our results are discussed in light of the recent discontinuation of clinical trials of more advanced IDO1 inhibitors and the reconsideration of IDO1 as a valid drug target.
Journal Article
Exploring the variations in ambient BTEX in urban Europe and its environmental health implications
2025
BTEX (benzene, toluene, ethylbenzene, m,p,o-xylene) are significant urban air pollutants. This study examines BTEX variability across seven European countries using data from 22 monitoring sites in different urban settings (urban background, traffic, industry, and suburban background). Results indicate that the relative abundance of BTEX in urban areas follows the order: toluene > benzene > m,p-xylene > o-xylene > ethylbenzene, with mean mixing ratios of 391 ± 451, 252 ± 324, 222 ± 297, 92 ± 119, and 78 ± 107 ppt from 2017 to 2022, respectively. Seasonal trends show benzene had similar median concentrations across urban background, traffic, and industrial sites, indicating mixed sources. Toluene levels were highest in traffic and industrial areas, highlighting road traffic and industrial emissions. Ethylbenzene and xylenes showed equivalent levels in traffic and industrial areas but were lower in urban backgrounds. Peak BTEX levels occurred during morning and evening rush hours, linked to traffic, heating, and atmospheric stagnation. B/T ratios ranged from 0.29 ± 0.11 to 1.35 ± 0.95, and X/E ratios ranged from 1.75 ± 0.91 to 3.68 ± 0.30, indicating primary pollution from local traffic, followed by solvents, coatings, and biomass burning. Lifetime Cancer Risk (LCR) values for BTEX exposure were below the definite risk threshold (10−4) but above the permissible risk level (10−6), suggesting moderate risk from benzene and ethylbenzene, particularly in traffic and industrial areas. This study offers essential insights into BTEX pollution in European urban environments.
Journal Article