H Lehnert

University Medical Center Schleswig-Holstein, Kiel, Schleswig-Holstein, Germany

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Publications (441)1152.25 Total impact

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    ABSTRACT: Neuroendocrine neoplasia (NEN) with unknown primary site (NEN-CUP tumors) may have a poor prognosis. We evaluated the clinical presentation, therapy, outcome, and risk factors for adverse outcomes in patients who had these tumors. In 243 patients who had NEN, a retrospective review was performed in 38 patients who had NEN-CUP tumors. The 38 patients who had NEN-CUP tumors were evaluated in three groups: group 1 (surgery; primary tumor detected; ten patients); group 2 (surgery; no primary tumor detected; ten patients); and group 3 (no surgery; 18 patients). Risk factors were evaluated with univariate and multivariate analyses. Most patients who had NEN-CUP tumors [32 patients (84 %)] had World Health Organization (WHO) performance score of 0 or 1, and most tumors [24 patients (63 %)] were well differentiated (WHO grade, G1 or G2; Ki-67 index, ≤20 %). Univariate analysis showed that greater survival was significantly associated with lower patient age, lower WHO performance score, lower WHO grade, lower number of metastatic sites, treatment with surgery, and no treatment with chemotherapy. Multivariate analysis showed that low WHO performance score (hazard ratio 7.63, 95 % confidence interval (CI) 2.63-22.19) and treatment with surgery (hazard ratio 0.10, CI 0.028-0.381) were significant independent predictors of improved survival. In patients with NEN-CUP tumors, surgical treatment is an independent predictor of better survival. Therefore, surgical treatment may be indicated in patients with good general health status and well-differentiated NEN-CUP tumors.
    World Journal of Surgery 02/2015; · 2.35 Impact Factor
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    ABSTRACT: The incidence of obesity in the western world has increased dramatically during recent decades. Epidemiological data suggest that obesity is associated with an increased risk of several but not all types of cancers, with clear sex-specific differences. The underlying mechanisms are still a matter of debate. This review focuses on the potential factors linking obesity to cancer. Current experimental evidence suggests that insulin resistance and a chronic, subclinical inflammation in the visceral fat are the major metabolic events causing alterations in the levels of insulin, glucose, free fatty acids, insulin-like growth factor 1 (IGF-1) and 2, adipose tissue-derived proinflammatory cytokines and other bioactive molecules, such as adipokines (e.g. leptin and adiponectin), vascular endothelial growth factor (VEGF), sex hormones, gut microbiota and secondary bile acids. All these factors may act directly or indirectly on the tumor microenvironment to drive tumor progression via stimulation of cell survival/antiapoptosis, cell proliferation, angiogenesis and invasion/metastasis of the cancer cells. Therapeutic strategies that target dysfunctional or inflamed fat and have been shown to benefit patients include bariatric surgery, while other cell or hormone-directed interventions, such as conversion of visceral fat macrophages to an anti-inflammatory M2 phenotype or the pharmacological modulation of serum adipokine levels are still theoretical and need to be clinically evaluated for their ability to successfully treat or prevent obesity-related cancers.
    Der Internist 02/2015; · 0.27 Impact Factor
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    ABSTRACT: To investigate the prognostic role of genomic stability and copy number alterations (CNAs) pancreatic neuroendocrine tumors (PanNETs). A high-resolution array-based comparative genomic hybridization approach was utilized in order to investigate and quantify chromosomal aberrations in a panel of 37 primary PanNET and 11 metastatic samples. DNA samples were extracted from formalin-fixed and paraffin-embedded tumor specimen. Genomic findings were correlated with histopathological and immunohistochemical data. Moreover, the dataset was subjected to employing an unsupervised hierarchical clustering analysis approach utilizing Euclidean distance and average linkage and associations between genomically defined tumor groups and recurrent CNAs or clinicopathological features of the study group were assessed. Numerous chromosomal aberrations were recurrently detected in both, primary tumor samples and metastases. Copy number gains were most frequently observed at 06p22.2-p22.1 (27.1%), 17p13.1 (20.8%), 07p21.3-p21.2 (18.8%), 09q34.11 (18.8%). Genomic losses were significantly less frequent and the only recurrent aberration affected 08q24.3 (6.3%). Moreover, we detected a high degree of genomic heterogeneity between primary tumors and metastatic lesions. Unsupervised hierarchical clustering of loci affected by CNAs in more than 3 primary tumor samples revealed two genetically distinct tumor groups as well as two chromosomal clusters of genomic imbalances indicating a small subset of tumors with common molecular features (13.5%). Aberrations affecting 6p22.2-22.1, 8q24.3, 9q34.11 and 17p13.1 (P = 0.011; 0.003; 0.003; 0.001), were significantly associated with a poorer survival prognosis. This study suggests that several frequent CNAs in numerous candidate regions are involved in the pathogenesis and metastatic progression of PanNET.
    World journal of gastroenterology : WJG. 12/2014; 20(46):17498-506.
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    ABSTRACT: Context: Primary extranodal diffuse large B-cell lymphomas of the thyroid (ptDLBCL) constitute a rare entity, which until now are not fully explored. Objective: Due to recently published data genetically linking ptDLBCL to a subset of thyroid carcinoma, we assessed the occurrence of oncogenic mutations and copy number alterations (CNAs). Design: A high-resolution array-based comparative genomic hybridization approach (aCGH) was applied to quantify genomic aberrations in a study population of 21 ptDLBCL. Further, we investigated the frequency of mutations involving the BRAF, NRAS and MYD88-genes in correlation with immunohistochemical data. Results: Chromosomal gains were recurrently detected at 6p21.33-p21.31, 6p22.2, 12p13.31, 14q31.1, 14q32.33, 19p13.3 and 22q11.22, numeric losses were most frequently observed at 6p21.3-p21.31, 10q26.3, 19p13.3, 20q13.33 and 21q11.2. Aberrations affecting 6p22.2 and 14q32.33 as well as 22q11.22 differed slightly between GCB- and non-GCB-groups. Statistically significant deviations were detected at 20q13.33 and 21q11.2. These specific alterations do not seem to occur in thyroid carcinomas or other DLBCL, according to previously published literature. Analysis of BRAF and NRAS showed mutation frequencies of 4.8 % and 9.5 %, respectively. No MYD88 mutations could be detected in any of the analyzed cases. Fluorescence in situ hybridization demonstrated breakage events involving the BCL2-, BCL6- and cMYC-locus in 14.3%, 9.5% and 9.5%, respectively. Conclusions: Our study revealed ptDLBCL to be predominantly composed of the GCB-type, harboring no MYD88 mutations and showing infrequent mutations in the BRAF and NRAS genes. Additionally, aCGH showed no overlapping alterations between ptDLBCL and thyroid carcinomas or other nodal or extranodal DLBCL.
    Journal of Clinical Endocrinology &amp Metabolism 11/2014; 100(2):jc20143250. · 6.31 Impact Factor
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    ABSTRACT: Experiments in rodents suggest that hypothalamic insulin signaling essentially contributes to the acute control of peripheral glucose homeostasis. Against this background, we investigated in healthy humans whether intranasal (IN) insulin, which is known to effectively reach the brain compartment, impacts systemic glucose metabolism. Twenty overnight-fasted healthy, normal-weight men were IN administered 210 and 420 IU (10 and 20 IU every 15 min) of the insulin analogue aspart (ins-asp) and placebo, respectively, during experimental sessions lasting 6 h. The use of ins-asp rather than human insulin enabled us to disentangle exogenous and endogenous insulin kinetics. IN insulin dose-dependently decreased plasma glucose concentrations while reducing C-peptide and attenuating endogenous insulin levels. However, we also observed a slight dose-dependent permeation of ins-asp into the circulation. In control experiments mimicking the systemic but not the central nervous uptake of the IN 210 IU dose via IV infusion of ins-asp at a dose of 0.12 mIU/kg/24h (n=10), we obtained essentially identical effects on fasting plasma glucose concentrations. This pattern indicates that sustained IN insulin administration to the human brain to enhance central nervous insulin signaling does not acutely alter systemic glucose homeostasis beyond effects accounted for by concurrent mild hyperinsulinemia.
    Diabetes 10/2014; · 7.90 Impact Factor
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    ABSTRACT: Primary mediastinal large B-cell lymphoma (PMBL) is a distinct subtype of diffuse large B-cell lymphoma (DLBCL) frequently observed in young patients. High-dose immunochemotherapy constitutes the current therapeutic gold-standard, despite significant toxicity and serious late effects. Several hotspots harboring oncogenic gain-of-function mutations were recently shown to pose vital hallmarks in activated B-cell like (ABC-) (CD79B, CARD11 and MYD88) and germinal center like (GCB-) DLBCL (EZH2), respectively. Several promising targeted-therapy approaches, derived from these findings, are currently under development.
    Anticancer research 10/2014; 34(10):5503-7. · 1.87 Impact Factor
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    ABSTRACT: Objectives The corticotrophin-releasing factor (CRF)/urocortin system is expressed in the adipose tissue of mammals but its functional role in this tissue remains unknown.Methods Pharmacological manipulation of CRF-Receptors, CRF1 and CRF2, activity was performed in 3T3L1 white pre-adipocytes and T37i brown pre-adipocytes during in vitro differentiation. The expression of genes of the CRF/Urocortin system and of markers of white and brown adipocytes was evaluated along with mitochondrial biogenesis and cellular oxygen consumption. Metabolic evaluation of corticosterone-deficient or supplemented Crhr null (Crhr(-/-)) mice and their wild-type controls was performed along with gene expression analysis carried out in white (WAT) and brown (BAT) adipose tissues.ResultsPeptides of the CRF/Urocortin system and their cognate receptors were expressed in both pre-adipocyte cell lines. In vitro pharmacological studies showed an inhibition of the expression of the CRF2 pathway by the constitutive activity of the CRF1 pathway. Pharmacological activation of CRF2 and, to a lesser extent, inhibition of CRF1 signaling induced molecular and functional changes indicating transdifferentiation of white pre-adipocytes and differentiation of brown pre-adipocytes. Crhr(-/-) mice showed increased expression of CRF2 and its agonist Urocortin 2 in adipocytes that was associated to brown conversion of WAT and activation of BAT. Crhr(-/-) mice were resistant to diet-induced obesity and glucose intolerance. Restoring physiological circulating corticosterone levels abrogated molecular changes in adipocytes and the favorable phenotype of Crhr(-/-) mice.Conclusions Our findings suggest the importance of the CRF2 pathway in the control of adipocyte plasticity. Increased CRF2 activity in adipocytes induces browning of WAT, differentiation of BAT and is associated with a favorable metabolic phenotype in mice lacking CRF1. Circulating corticosterone represses CRF2 activity in adipocytes and may thus regulate adipocyte physiology through the modulation of the local CRF/Urocortin system. Targeting CRF-receptor signaling specifically in the adipose tissue may represent a novel approach to tackle obesity.International Journal of Obesity accepted article preview online, 05 September 2014. doi:10.1038/ijo.2014.164.
    International journal of obesity (2005) 09/2014; · 5.22 Impact Factor
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    ABSTRACT: To show a rare case of Cushing's disease and possible cause of failed transsphenoidal surgery.
    Pituitary 08/2014; · 2.22 Impact Factor
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    ABSTRACT: The attenuated counterregulatory response to hypoglycaemia following antecedent hypoglycaemic episodes is associated with an increase in gamma-aminobutyric acid (GABA) signalling. We therefore tested the hypothesis that the pharmacological suppression of GABAergic activity during a repeated hypoglycaemic episode enhances counterregulatory responses. Fourteen healthy men participated in two experimental sessions each comprising three insulin-induced hypoglycaemic episodes. Before the third hypogylcaemia, participants received the GABA-antagonistic drug modafinil (200 mg orally) and placebo, respectively. In the placebo condition, the secretion of norepinephrine, ACTH, cortisol, and growth hormone and the perception of neuroglycopenic symptoms were attenuated during the third as compared to the first hypoglycaemic episode (each P<0.05). Modafinil reversed this effect for the noradrenergic response (P<0.05) while the attenuation of other hormonal responses and the perception of symptoms were not significantly affected (P>0.3). Our findings indicate that increases in GABAergic signalling could contribute to aspects of the attenuated counterregulatory response following recurrent hypoglycaemia in humans.
    Diabetes Obesity and Metabolism 07/2014; · 5.18 Impact Factor
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    ABSTRACT: Enteroendocrine cells (EEC) produce neuropeptides, which are crucially involved in the maintenance of the intestinal barrier. Hence, EEC dysfunction is suggested to be involved in the complex pathophysiology of inflammatory bowel disease (IBD), which is characterized by decreased intestinal barrier function. However, the underlying mechanisms for EEC dysfunction are not clear and suitable models for a better understanding are lacking. Here, we demonstrate that Carboxypeptidase E (CPE) is specifically expressed in EEC of the murine colon and ileum and that its deficiency is associated with reduced intestinal levels of Neuropeptide Y (NPY) and Peptide YY (PYY), which are both produced by EEC. Moreover, cpe-/- mice exhibit an aggravated course of DSS-induced chronic colitis compared to wildtype littermates. In addition, we observed elevated mucosal IL-6 and KC transcript levels already at baseline conditions in cpe-/- mice. Moreover, supernatants obtained from isolated intestinal crypts of cpe-/- mice lead to increased IL-6 and KC expression in MODE-K cells in the presence of LPS. This effect was reversible by co-administration of recombinant NPY, suggesting a CPE mediated immunosuppressive effect in the intestines by influencing the processing of specific neuropeptides. In this context, the chemotaxis of bone marrow derived macrophages towards respective supernatants was enhanced. In conclusion, our data point to an anti-inflammatory role of CPE in the intestine by influencing local cytokine levels and thus regulating the migration of myeloid immune cells into the mucosa. These findings highlight the importance of EEC for intestinal homeostasis and propose EEC as potential therapeutic targets in IBD.
    PLoS ONE 07/2014; 9(7):e102347. · 3.53 Impact Factor
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    ABSTRACT: ABSTRACT Epstein-Barr Virus- (EBV) associated diffuse large B-cell lymphoma (DLBCL) of the elderly constitutes a provisional clinicopathological entity in the current WHO Classification and its genomic features remain sparsely characterized. We investigated a cohort of 26 untreated de novo EBV-positive DLBCL of the elderly by high-resolution array-based comparative genomic profiling and FISH. Moreover, we screened for activating mutations affecting nuclear factor (NF)-kappa B pathway signaling and chromatin remodeling (EZH2, CD79B, CARD11 and MYD88) due to their impact of gene expression signatures and postulated upcoming therapeutic targetability. We identified an overlap between genomic aberrations previously described to be exclusive features of plasmablastic lymphoma (PL), post-transplant lymphoprolierative disorders (PTLD) and DLBCL, respectively, indicating a close cytogenetic relation between these entities. Few mutations affecting CD79B and CARD11 and no MYD88 mutations were detectable hinting at an EBV-mediated activation of NF-kappa B as an alternative to pathologically enforced B-cell receptor signaling in this rare entity.
    Leukemia and Lymphoma 07/2014; · 2.61 Impact Factor
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    ABSTRACT: Telomerase reverse transcriptase (TERT) is a key component of the telomerase complex. By lengthening telomeres in DNA strands, TERT increases senescent cell lifespan. Mice that lack TERT age much faster and exhibit age-related conditions such as osteoporosis, diabetes and neurodegeneration. Accelerated telomere shortening in both human and animal models has been documented in conditions associated with insulin resistance, including T2DM.
    Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease 06/2014; · 5.09 Impact Factor
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    ABSTRACT: Pancreatic neuroendocrine neoplasms (pNEN) are rare tumors with a poor prognosis. Although increasing data have accumulated on the molecular pathology of pNEN, very scarce data exist on microRNAs in pNEN and no data are published on microRNAs as potential biomarkers of pNEN in serum. This study aimed to identify microRNA signatures of pNEN in tissue and serum. We included tissue samples from 37 patients with pNEN, 9 patients with non-neoplastic pancreatic pathology, seven samples of micro-dissected pancreatic islets and serum samples of 27 patients with pNEN, as well as of 15 healthy volunteers. MicroRNA expression profiles were established using real-time quantitative Polymerase Chain reaction (PCR) for 754 microRNAs. MicroRNA signatures differed between pNEN, pancreatic islets and total pancreas, with virtually no overlap between the groups of de-regulated microRNAs. Expression of miR-642 correlated with Ki67 (MiB1) score and miR-210 correlated with metastatic disease. When comparing microRNA levels in serum from patients with pNEN and healthy volunteers, 13 microRNAs were more abundant in the serum of patients. MiR-193b was also up-regulated in pNEN tissue when compared to pancreatic islets and remained significantly increased in serum even when corrected for multiple testing. Evaluation of microRNAs appears to be promising in the assessment of pNEN. In particular, miR-193b, which is also increased in serum, may be a potential new biomarker of pNEN.
    Anticancer research 05/2014; 34(5):2249-54. · 1.87 Impact Factor
  • Endocrine Abstracts. 04/2014;
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    Volker Ott, Henrik Oster, Hendrik Lehnert
    Molecular metabolism. 04/2014; 3(2):84-5.
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    ABSTRACT: Human adipose-derived stroma cells (ADSCs) have successfully been employed in explorative therapeutic studies. Current evidence suggests that ADSCs are unevenly distributed in subcutaneous adipose tissue; therefore, the anatomic origin of ADSCs may influence clinical outcomes. This study was designed to investigate proliferation and differentiation capacities of ADSCs from the gluteal and abdominal depot of 8 females. All had normal BMI (22.01 ± 0.39 kg/m(2) ) and waist circumference (81.13 ± 2.33 cm). Examination by physicians and analysis of 31 laboratory parameters did not reveal possibly confounding medical disorders. Gluteal and abdominal adipose tissue was sampled by en-bloc resection on day 7 (±1) after the last menses. Histological examination did not reveal significant depot-specific differences. As assessed by BrdU assay, proliferation of cells from both depots was similar after 24 hours and analysis of 15 cell surface markers by flow cytometry identified the isolated cells as ADSCs, again without depot-specific differences. ADSCs from both depots differentiated poorly to chondroblasts. Gluteal ADSCs displayed significantly higher adipogenic differentiation potential than abdominal cells. Osteogenic differentiation was most pronounced in gluteal cells, whereas differentiation of abdominal ADSCs was severely impaired. Our data demonstrate a depot-specific difference in ADSC differentiation potential with abdominal cells failing to meet the criteria of multipotent ADSCs. This finding should be taken into account in future explorations of ADSC-derived therapeutic strategies. This article is protected by copyright. All rights reserved.
    Experimental Dermatology 04/2014; · 4.12 Impact Factor
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    ABSTRACT: Objective: Energy homeostasis results from a balance of food intake and energy expenditure, accomplished by the interaction of peripheral and central nervous signals. The recently discovered adipokine nesfatin-1 is involved in the central control of food intake, but whether it also participates in the regulation of thermogenesis is unknown. Design and Methods: We administered nesfatin-1 intracerebroventricularly to freely moving, male Wistar rats and performed direct calorimetry to assess its effects on thermogenesis. Furthermore, we measured food intake and determined hypothalamic and N. tractus solitarius neuropeptide expression by quantitative real-time PCR. Leptin, which is involved in both the regulation of food intake and thermogenesis, was used as positive control. Results: We could for the first time show that central nervous administration of nesfatin-1 profoundly increases thermogenesis in rats to a similar extent as leptin and confirmed the role of both peptides in the control of food intake. Nesfatin-1 significantly downregulated neuropeptide Y mRNA expression in both hypothalamus and N. tractus solitarius. Conclusions: The results of our strongly support the prominent role of nesfatin-1 for both food intake and energy expenditure and neuropeptide Y neurons appear to be involved in this effect.
    Obesity 03/2014; · 4.39 Impact Factor
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    ABSTRACT: To date, malignant pheochromocytomas and paragangliomas (PHEOs/PGLs) cannot be effectively cured and thus novel treatment strategies are urgently needed. Lovastatin has been shown to effectively induce apoptosis in mouse PHEO cells (MPC) and the more aggressive mouse tumor tissue-derived cells (MTT), which was accompanied by decreased phosphorylation of mitogen-activated kinase (MAPK) pathway players. The MAPK pathway plays a role in numerous aggressive tumors and has been associated with a subgroup of PHEOs/PGLs, including K-RAS-, RET-, and NF1-mutated tumors. Our aim was to establish whether MAPK signaling may also play a role in aggressive, succinate dehydrogenase (SDH) B mutation-derived PHEOs/PGLs. Expression profiling and western blot analysis indicated that specific aspects of MAPK-signaling are active in SDHB PHEOs/PGLs, suggesting that inhibition by statin treatment could be beneficial. Moreover, we aimed to assess whether the anti-proliferative effect of lovastatin on MPC and MTT differed from that exerted by fluvastatin, simvastatin, atorvastatin, pravastatin, or rosuvastatin. Simvastatin and fluvastatin decreased cell proliferation most effectively and the more aggressive MTT cells appeared more sensitive in this respect. Inhibition of MAPK1 and 3 phosphorylation following treatment with fluvastatin, simvastatin, and lovastatin was confirmed by western blot. Increased levels of CASP-3 and PARP cleavage confirmed induction of apoptosis following the treatment. At a concentration low enough not to affect cell proliferation, spontaneous migration of MPC and MTT was significantly inhibited within 24 hours of treatment. In conclusion, lipophilic statins may present a promising therapeutic option for treatment of aggressive human paragangliomas by inducing apoptosis and inhibiting tumor spread.
    PLoS ONE 03/2014; 9(5):e97712. · 3.53 Impact Factor
  • Experimental and Clinical Endocrinology & Diabetes 03/2014; 122(03). · 1.76 Impact Factor
  • B Harbeck, M J Berndt, H Lehnert
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    ABSTRACT: History and admission findings: A 51-year-old man presented with progressive tiredness, proximal muscle weakness, hair loss and weight gain for months. The patient showed mild pretibial myxedema and dry skin. Laboratory findings revealed strongly elevated cardiac enzymes as well as marked hypothyroidism. Investigations: The electrocardiogram, echocardiography, abdominal sonography and chest X-ray were unremarkable. Thyroid ultrasound demonstrated features of Hashimoto thyroiditis. Treatment and course: The findings supported the diagnosis of an overt hypothyroidism with myxedema and rhabdomyolysis. After starting levothyroxine and volume substitution laboratory parameters and clinical condition slowly normalized. Conclusion: Severe overt hypothyroidism may rarely present primarily as myopathy with myositis and cardiac involvement.
    DMW - Deutsche Medizinische Wochenschrift 03/2014; 139(10):483-5. · 0.65 Impact Factor

Publication Stats

5k Citations
1,152.25 Total Impact Points


  • 2009–2014
    • University Medical Center Schleswig-Holstein
      Kiel, Schleswig-Holstein, Germany
    • Klinikum Stuttgart
      Stuttgart, Baden-Württemberg, Germany
  • 2008–2014
    • Universität zu Lübeck
      • • Department of Internal Medicine I
      • • Department of Neuroendocrinology
      Lübeck Hansestadt, Schleswig-Holstein, Germany
  • 2006–2014
    • The University of Warwick
      • • Division of Metabolic and Vascular Health
      • • Warwick Medical School (WMS)
      Coventry, England, United Kingdom
  • 2010–2013
    • National Institutes of Health
      • • Branch of Radiation Oncology
      • • Program in Reproductive and Adult Endocrinology
      Bethesda, MD, United States
    • Leiden University Medical Centre
      • Department of Nephrology
      Leyden, South Holland, Netherlands
    • Universitätsklinikum Tübingen
      Tübingen, Baden-Württemberg, Germany
    • University of Hamburg
      • Department of Medical Psychology
      Hamburg, Hamburg, Germany
    • Robert-Bosch Krankenhaus
      Stuttgart, Baden-Württemberg, Germany
  • 2012
    • Eunice Kennedy Shriver National Institute of Child Health and Human Development
      Maryland, United States
  • 2011–2012
    • Goethe-Universität Frankfurt am Main
      • Zentrum der Inneren Medizin
      Frankfurt am Main, Hesse, Germany
  • 2007–2012
    • Universitätsklinikum Schleswig - Holstein
      Kiel, Schleswig-Holstein, Germany
    • University Hospitals Coventry and Warwickshire NHS Trust
      Coventry, England, United Kingdom
  • 2006–2011
    • Technische Universität Dresden
      • Institut für Klinische Pharmakologie
      Dresden, Saxony, Germany
  • 2009–2010
    • Ludwig-Maximilians-University of Munich
      • Department of Internal Medicine II
      München, Bavaria, Germany
  • 1994–2010
    • University Hospital Magdeburg
      Magdeburg, Saxony-Anhalt, Germany
  • 2005–2008
    • Coventry University
      Coventry, England, United Kingdom
  • 1995–2008
    • Otto-von-Guericke-Universität Magdeburg
      Magdeburg, Saxony-Anhalt, Germany
  • 2003
    • Max Planck Institute of Psychiatry
      München, Bavaria, Germany
    • Carl Gustav Carus-Institut
      Pforzheim, Baden-Württemberg, Germany
  • 1988–2000
    • Johannes Gutenberg-Universität Mainz
      • • III. Department of Medicine
      • • Abteilung für Retinologie
      Mayence, Rheinland-Pfalz, Germany
  • 1991
    • Max Planck Institute for Experimental Medicine
      Göttingen, Lower Saxony, Germany
  • 1987
    • Harvard University
      • Department of Nutrition
      Boston, MA, United States
  • 1984–1986
    • Massachusetts Institute of Technology
      • Department of Brain and Cognitive Sciences
      Cambridge, Massachusetts, United States