Publications by authors named "Marcus Winter"

14 Publications

  • Page 1 of 1

Willingness, concerns, incentives and acceptable remuneration regarding an involvement in teaching undergraduates - a cross-sectional questionnaire survey among German GPs.

BMC Med Educ 2019 Jan 25;19(1):33. Epub 2019 Jan 25.

Institute of General Practice and Family Medicine, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.

Background: Worldwide, many undergraduate general practice curricula include community-based courses at general practitioners' (GPs') offices. Usually the academic general practice departments collaborate with networks of affiliated teaching practices. To successfully master the challenge of network development and extension, more information is needed about GPs' willingness to be involved in different teaching formats, important influencing factors, incentives, barriers, and the need for financial compensation.

Methods: In this cross-sectional study a questionnaire survey was conducted among all GPs working in Leipzig and environs (German postal code area 04). In addition to descriptive statistics, group comparisons and logistic regression were performed to reveal differences between GPs with and without an interest in teaching.

Results: Response rate was 45.3% with 339 analyzable questionnaires. The average age was 52.0 years and 58.4% were women. Sixty-two participants stated that they were already involved in teaching undergraduates. Altogether 60.1% of all GPs and 53.5% among those who didn't teach yet were basically interested in being involved in undergraduate education. The interested GPs could imagine devoting on average 6.9 h per month to teaching activities. GPs interested in teaching were on average younger, were more actively involved in continuing education and professional associations, and more frequently had pre-existing teaching experiences. The willingness to teach differed substantially among teaching formats. GPs were more willing to teach at their own practices rather than at university venues and they preferred skills-oriented content. Comprehensive organization on the part of the university including long-term scheduling and available teaching materials was rated as most important to increase the attractiveness of teaching. Time restraints and decreased productivity were rated as the most important barriers. Interested GPs appreciated financial compensation, particularly for teaching at university venues, and demanded amounts of money corresponding to German GPs' hourly income.

Conclusions: The GPs' interest in undergraduate teaching is generally high indicating a substantial pool of potential preceptors. Recruitment strategies should consider the collaboration with institutions involved in residency and continuing education as well as with professional associations. Comprehensive organization by the responsible department should be promoted and time restraints and decreased productivity should be overtly addressed and financially compensated.
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http://dx.doi.org/10.1186/s12909-018-1445-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6347773PMC
January 2019

Mechanistic Study of Belinostat Oral Absorption From Spray-Dried Dispersions.

J Pharm Sci 2019 Jan 6;108(1):326-336. Epub 2018 Oct 6.

Drug Product Development and Innovation, Lonza Pharma and Biotech, Bend, Oregon 97703.

Spray-dried dispersions (SDDs) are an important technology for enhancing the oral bioavailability of poorly water-soluble drugs. To design an effective oral SDD formulation, the key rate-determining step(s) for oral drug absorption must be understood. This work combined in vivo and in vitro tests with in silico modeling to identify the rate-determining steps for oral absorption of belinostat SDDs made with 3 different polymers (PVP K30, PVP VA64, and HPMCAS-M). The goal was developing a belinostat SDD formulation that maximizes oral bioavailability (ideally matching the performance of a belinostat oral solution) and defining critical performance attributes for formulation optimization. The in vivo pharmacokinetic study with beagle dogs demonstrated that 1 of the 3 SDDs (PVP K30 SDD) matched the performance of the oral solution. In vitro data coupled with in silico modeling elucidated differences among the SDDs and supported the hypothesis that absorption of belinostat in the small intestine from the other 2 SDDs (PVP VA64 and HPMCAS-M) may be limited by dissolution rate or reduced drug activity (maximum concentration) in the presence of polymer. It was concluded that drug concentration in the stomach before emptying into the proximal intestine is a key factor for maximizing in vivo performance.
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http://dx.doi.org/10.1016/j.xphs.2018.09.031DOI Listing
January 2019

Early-onset childhood atopic dermatitis is related to NLRP2 repression.

J Allergy Clin Immunol 2018 04 9;141(4):1482-1485.e16. Epub 2017 Dec 9.

Department of Environmental Immunology, Helmholtz Centre for Environmental Research Leipzig, Leipzig, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2017.11.018DOI Listing
April 2018

The benzene metabolite 1,4-benzoquinone reduces regulatory T-cell function: A potential mechanism for tobacco smoke-associated atopic dermatitis.

J Allergy Clin Immunol 2017 08 6;140(2):603-605. Epub 2017 Mar 6.

Department of Environmental Immunology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2017.01.034DOI Listing
August 2017

Environment-induced epigenetic reprogramming in genomic regulatory elements in smoking mothers and their children.

Mol Syst Biol 2016 Mar 24;12(3):861. Epub 2016 Mar 24.

Department of Environmental Immunology, Helmholtz Centre for Environmental Research Leipzig - UFZ, Leipzig, Germany

Epigenetic mechanisms have emerged as links between prenatal environmental exposure and disease risk later in life. Here, we studied epigenetic changes associated with maternal smoking at base pair resolution by mapping DNA methylation, histone modifications, and transcription in expectant mothers and their newborn children. We found extensive global differential methylation and carefully evaluated these changes to separate environment associated from genotype-related DNA methylation changes. Differential methylation is enriched in enhancer elements and targets in particular "commuting" enhancers having multiple, regulatory interactions with distal genes. Longitudinal whole-genome bisulfite sequencing revealed that DNA methylation changes associated with maternal smoking persist over years of life. Particularly in children prenatal environmental exposure leads to chromatin transitions into a hyperactive state. Combined DNA methylation, histone modification, and gene expression analyses indicate that differential methylation in enhancer regions is more often functionally translated than methylation changes in promoters or non-regulatory elements. Finally, we show that epigenetic deregulation of a commuting enhancer targeting c-Jun N-terminal kinase 2 (JNK2) is linked to impaired lung function in early childhood.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4812527PMC
http://dx.doi.org/10.15252/msb.20156520DOI Listing
March 2016

S-phase-specific radiosensitization by gemcitabine for therapeutic carbon ion exposure in vitro.

J Radiat Res 2016 Mar 7;57(2):110-4. Epub 2016 Jan 7.

Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany.

Densely ionizing charged particle irradiation offers physical as well as biological advantages compared with photon irradiation. Radiobiological data for the combination of such particle irradiation (i.e. therapeutic carbon ions) with commonly used chemotherapeutics are still limited. Recent in vitro results indicate a general prevalence of additive cytotoxic effects in combined treatments, but an extension of established multimodal treatment regimens with photons to the inclusion of particle therapy needs to evaluate possible peculiarities of using high linear energy transfer (LET) radiation. The present study investigates the effect of combined radiochemotherapy using gemcitabine and high-LET irradiation with therapeutic carbon ions. In particular, the earlier observation of S-phase specific radiosensitization with photon irradiation should be evaluated with carbon ions. In the absence of the drug gemcitabine, carbon ion irradiation produced the typical survival behavior seen with X-rays-increased relative biological efficiency, and depletion of the survival curve's shoulder. By means of serum deprivation and subsequent replenishment, ∼70% S-phase content of the cell population was achieved, and such preparations showed radioresistance in both treatment arms-,photon and carbon ion irradiation. Combined modality treatment with gemcitabine caused significant reduction of clonogenic survival especially for the S-phase cells. WIDR cells exhibited S-phase-specific radioresistance with high-LET irradiation, although this was less pronounced than for X-ray exposure. The combined treatment with therapeutic carbon ions and gemcitabine caused the resistance phenomenon to disappear phenotypically.
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http://dx.doi.org/10.1093/jrr/rrv097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4795954PMC
March 2016

Constitutive IDO expression in human cancer is sustained by an autocrine signaling loop involving IL-6, STAT3 and the AHR.

Oncotarget 2014 Feb;5(4):1038-51

Department of Neurooncology, Neurology Clinic and National Center for Tumor Diseases University Hospital of Heidelberg, Heidelberg, Germany.

Indoleamine-2,3-dioxygenase (IDO) inhibitors have entered clinical trials based on their ability to restore anti-tumor immunity in preclinical studies. However, the mechanisms leading to constitutive expression of IDO in human tumors are largely unknown. Here we analyzed the pathways mediating constitutive IDO expression in human cancer. IDO-positive tumor cells and tissues showed basal phosphorylation and acetylation of STAT3 as evidenced by western blotting and immunoprecipitation. Inhibition of IL-6 or STAT3 using siRNA and/or pharmacological inhibitors reduced IDO mRNA and protein expression as well as kynurenine formation. In turn, IDO enzymatic activity activated the AHR as shown by the induction of AHR target genes. IDO-mediated AHR activation induced IL-6 expression, while inhibition or knockdown of the AHR reduced IL-6 expression. IDO activity thus sustains its own expression via an autocrine AHR-IL-6-STAT3 signaling loop. Inhibition of the AHR-IL-6-STAT3 signaling loop restored T-cell proliferation in mixed leukocyte reactions performed in the presence of IDO-expressing human cancer cells. Identification of the IDO-AHR-IL-6-STAT3 signaling loop maintaining IDO expression in human cancers reveals novel therapeutic targets for the inhibition of this core pathway promoting immunosuppression of human cancers. The relevance of the IDO-AHR-IL-6-STAT3 transcriptional circuit is underscored by the finding that high expression of its members IDO, STAT3 and the AHR target gene CYP1B1 is associated with reduced relapse-free survival in lung cancer patients.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4011581PMC
http://dx.doi.org/10.18632/oncotarget.1637DOI Listing
February 2014

Analysis of inter- and intrafraction accuracy of a commercial thermoplastic mask system used for image-guided particle radiation therapy.

J Radiat Res 2013 Jul;54 Suppl 1:i69-76

Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg, Germany.

The present paper reports and discusses the results concerning both the inter- and intrafraction accuracy achievable combining the immobilization system employed in patients with head-and-neck, brain and skull base tumors with image guidance at our particle therapy center. Moreover, we investigated the influence of intrafraction time on positioning displacements. A total of 41 patients treated between January and July 2011 represented the study population. All the patients were immobilized with a tailored commercial thermoplastic head mask with standard head-neck rest (HeadSTEP(®), IT-V). Patient treatment position was verified by two orthogonal kilovoltage images acquired through a ceiling imaging robot (Siemens, Erlangen, Germany). The analysis of the applied daily corrections during the first treatment week before and after treatment delivery allowed the evaluation of the interfraction and intrafraction reproducibility of the thermoplastic mask, respectively. Concerning interfraction reproducibility, translational and rotational systematic errors (Σs) were ≤ 2.2 mm and 0.9º, respectively; translational and rotational random errors (σs) were ≤ 1.6 mm and 0.6º, respectively. Regarding the intrafraction accuracy translational and rotational Σs were ≤ 0.4 mm and 0.4º, respectively; translational and rotational σs were ≤ 0.5 mm and 0.3º, respectively. Concerning the time-intrafraction displacements correlation Pearson coefficient was 0.5 for treatment fractions with time between position checks less than or equal to median value, and 0.2 for those with time between position controls longer than the median figure. These results suggest that intrafractional patient motion is smaller than interfractional patient motion. Moreover, we can state that application of different imaging verification protocols translate into a relevant difference of accuracy for the same immobilization device. The magnitude of intrafraction displacements correlates with the time for short treatment sessions or during the early phase of long treatment delivery.
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http://dx.doi.org/10.1093/jrr/rrt038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3700507PMC
July 2013

Accuracy of robotic patient positioners used in ion beam therapy.

Radiat Oncol 2013 May 21;8:124. Epub 2013 May 21.

Heidelberger Ionenstrahl-Therapiezentrum, Im Neuenheimer Feld 450, Heidelberg 69120, Germany.

Background: In this study we investigate the accuracy of industrial six axes robots employed for patient positioning at the Heidelberg Ion Beam Therapy Center.

Methods: In total 1018 patient setups were monitored with a laser tracker and subsequently analyzed. The measurements were performed in the two rooms with a fixed horizontal beam line. Both, the 3d translational errors and the rotational errors around the three table axes were determined.

Results: For the first room the 3d error was smaller than 0.72 mm in 95 percent of all setups. The standard deviation of the rotational errors was at most 0.026° for all axes. For the second room Siemens implemented an improved approach strategy to the final couch positions. The 95 percent quantile of the 3d error could in this room be reduced to 0.53 mm; the standard deviation of the rotational errors was also at most 0.026°.

Conclusions: Robots are very flexible tools for patient positioning in six degrees of freedom. This study proved that the robots are able to achieve clinically acceptable accuracy in real patient setups, too.
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http://dx.doi.org/10.1186/1748-717X-8-124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3749753PMC
May 2013

Robotic-based carbon ion therapy and patient positioning in 6 degrees of freedom: setup accuracy of two standard immobilization devices used in carbon ion therapy and IMRT.

Radiat Oncol 2012 Mar 29;7:51. Epub 2012 Mar 29.

Department of Radiation Oncology, University of Heidelberg, INF 400, Heidelberg 69120, Germany.

Purpose: To investigate repositioning accuracy in particle radiotherapy in 6 degrees of freedom (DOF) and intensity-modulated radiotherapy (IMRT, 3 DOF) for two immobilization devices (Scotchcast masks vs thermoplastic head masks) currently in use at our institution for fractionated radiation therapy in head and neck cancer patients.

Methods And Materials: Position verifications in patients treated with carbon ion therapy and IMRT for head and neck malignancies were evaluated. Most patients received combined treatment regimen (IMRT plus carbon ion boost), immobilization was achieved with either Scotchcast or thermoplastic head masks. Position corrections in robotic-based carbon ion therapy allowing 6 DOF were compared to IMRT allowing corrections in 3 DOF for two standard immobilization devices. In total, 838 set-up controls of 38 patients were analyzed.

Results: Robotic-based position correction including correction of rotations was well tolerated and without discomfort. Standard deviations of translational components were between 0.5 and 0.8 mm for Scotchcast and 0.7 and 1.3 mm for thermoplastic masks in 6 DOF and 1.2-1.4 mm and 1.0-1.1 mm in 3 DOF respectively. Mean overall displacement vectors were between 2.1 mm (Scotchcast) and 2.9 mm (thermoplastic masks) in 6 DOF and 3.9-3.0 mm in 3 DOF respectively. Displacement vectors were lower when correction in 6 DOF was allowed as opposed to 3 DOF only, which was maintained at the traditional action level of >3 mm for position correction in the pre-on-board imaging era.

Conclusion: Setup accuracy for both systems was within the expected range. Smaller shifts were required when 6 DOF were available for correction as opposed to 3 DOF. Where highest possible positioning accuracy is required, frequent image guidance is mandatory to achieve best possible plan delivery and maintenance of sharp gradients and optimal normal tissue sparing inherent in carbon ion therapy.
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http://dx.doi.org/10.1186/1748-717X-7-51DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3337272PMC
March 2012

In vitro evaluation of photon and carbon ion radiotherapy in combination with chemotherapy in glioblastoma cells.

Radiat Oncol 2012 Jan 27;7. Epub 2012 Jan 27.

Department of Radiation Oncology, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.

Background: To evaluate the cytotoxic effect of carbon ion radiotherapy and chemotherapy in glioblastoma cells in vitro.

Methods And Materials: The human glioblastoma (GBM) cell line U87 was irradiated with photon radiotherapy (RT) doses of 2 Gy, 4 Gy and 6 Gy. Likewise, irradiation with carbon ions was performed with single carbon doses of 0.125, 0.5, 2 and 3 Gy. Four chemotherapeutic substances, camptothecin, gemcitabine, paclitaxel and cisplatinum, were used for single and combination experiments. The assessment of the effect of single and double treatment on cell viability was performed using the clonogenic growth assay representing the radiobiological gold standard.

Results: The RBE of carbon ions ranges between 3.3 and 3.9 depending on survival level and dose. All chemotherapeutic substances showed a clear does-response relationhips. in their characteristic concentrations. For subsequent combination experiments, two dose levels leading to low and medium reduction of cell survival were chosen. Combination experiments showed additive effects independently of the drugs' mechanisms of action. Paclitaxel and campthothecin demonstrated the most prominent cytotoxic effect in combination with carbon ion radiotherapy.

Conclusion: In conclusion, combination of carbon ion radiotherapy with chemotherapies of different mechanisms of action demonstrates additive effects. The most dominant effect was produced by paclitaxel, followed by camptothecin, as espected from previously published work. The present data serve as an important radiobiological basis for further combination experiments, as well as clinical studies on combination treatments.
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http://dx.doi.org/10.1186/1748-717X-7-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3398277PMC
January 2012

Quantification of the relative biological effectiveness for ion beam radiotherapy: direct experimental comparison of proton and carbon ion beams and a novel approach for treatment planning.

Int J Radiat Oncol Biol Phys 2010 Nov 21;78(4):1177-83. Epub 2010 Aug 21.

Department of Biophysics, GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany.

Purpose: To present the first direct experimental in vitro comparison of the biological effectiveness of range-equivalent protons and carbon ion beams for Chinese hamster ovary cells exposed in a three-dimensional phantom using a pencil beam scanning technique and to compare the experimental data with a novel biophysical model.

Methods And Materials: Cell survival was measured in the phantom after irradiation with two opposing fields, thus mimicking the typical patient treatment scenario. The novel biophysical model represents a substantial extension of the local effect model, previously used for treatment planning in carbon ion therapy for more than 400 patients, and potentially can be used to predict effectiveness of all ion species relevant for radiotherapy. A key feature of the new approach is the more sophisticated consideration of spatially correlated damage induced by ion irradiation.

Results: The experimental data obtained for Chinese hamster ovary cells clearly demonstrate that higher cell killing is achieved in the target region with carbon ions as compared with protons when the effects in the entrance channel are comparable. The model predictions demonstrate agreement with these experimental data and with data obtained with helium ions under similar conditions. Good agreement is also achieved with relative biological effectiveness values reported in the literature for other cell lines for monoenergetic proton, helium, and carbon ions.

Conclusion: Both the experimental data and the new modeling approach are supportive of the advantages of carbon ions as compared with protons for treatment-like field configurations. Because the model predicts the effectiveness for several ion species with similar accuracy, it represents a powerful tool for further optimization and utilization of the potential of ion beams in tumor therapy.
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http://dx.doi.org/10.1016/j.ijrobp.2010.05.014DOI Listing
November 2010

Radiation-induced premature senescence is associated with specific cytogenetic changes.

Mutat Res 2010 Aug 23;701(1):60-6. Epub 2010 Mar 23.

GSI, Biophysics, Darmstadt, Germany.

In the present study, we set out to investigate cytogenetic changes in the progeny of two normal human fibroblast cell strains after exposure to sparsely or densely ionizing irradiation (X-rays or 9.8 MeV u(-1) carbon ions). The cells were regularly subcultured up to senescence. The transition to senescence was determined by measurement of population doubling numbers and senescence associated (SA) beta-galactosidase activity. Chromosomal changes (structural aberrations, tetraploidy) were investigated by solid staining. In temporal proximity to senescence, we observed for all populations of the two fibroblasts cell strains an increase in the fraction of cells with structural and numerical aberrations. The observed changes in the yield of structural chromosomal aberrations were similar for the progeny of controls and irradiated cells, except that a previous irradiation with a high, fractionated X-ray dose resulted in a stronger increase. Noteworthy, delayed tetraploidy in the descendants of irradiated cells exceeded the level in control cells. In addition, tetraploidy and the time of onset of senescence were significantly correlated for all populations, regardless of a preceding radiation exposure. However, the time of the onset of senescence depends on previous exposure to radiation. We conclude that the occurrence of tetraploidy is associated with senescence independently of exposure to radiation.
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http://dx.doi.org/10.1016/j.mrgentox.2010.03.010DOI Listing
August 2010

Interrelation amongst differentiation, senescence and genetic instability in long-term cultures of fibroblasts exposed to different radiation qualities.

Radiother Oncol 2007 Jun 17;83(3):277-82. Epub 2007 May 17.

Gesellschaft für Schwerionenforschung/Biophysik, Darmstadt, Germany.

Background And Purpose: The goal of the present study was to investigate aging and genetic instability in the progeny of human fibroblasts exposed to X-rays and carbon ions.

Materials And Methods: Following irradiation, cells were regularly subcultured until senescence. At selected time-points BrdU-labelling index, expression of cell cycle related proteins, cell differentiation pattern and chromosome aberrations were assessed.

Results: After exposure, an immediate cell cycle arrest occurred followed by a period of a few weeks where premature differentiation and senescence were observed. In all cultures cycling cells expressing low levels of cell cycle inhibiting proteins were present and finally dominated the populations. About 5months after exposure, the cellular and molecular changes attributed to differentiation and senescence reappeared and persisted. Concurrently, genetic instability was observed, but the aberration yields and types differed between repeated experiments. The descendants of cells exposed to carbon ions did not senesce earlier and displayed a similar rate of genetic instability as the X-ray progeny. For high doses an impaired cell cycle regulation and extended life span was observed, but finally cell proliferation ceased in all populations.

Conclusions: The descendants of irradiated fibroblasts undergo stepwise senescence and differentiation. Genetic instability is frequent and an extension of the life span may occur.
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http://dx.doi.org/10.1016/j.radonc.2007.04.022DOI Listing
June 2007