@article{BankogluStippGerberetal.2021,
  author    = {Bankoglu, Ezgi Eyluel and Stipp, Franzisca and Gerber, Johanna and Seyfried, Florian and Heidland, August and Bahner, Udo and Stopper, Helga},
  title     = {Effect of cryopreservation on DNA damage and DNA repair activity in human blood samples in the comet assay},
  series = {Archives of Toxicology},
  volume    = {95},
  journal   = {Archives of Toxicology},
  number    = {5},
  doi       = {10.1007/s00204-021-03012-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265326},
  pages     = {1831-1841},
  year      = {2021},
  abstract  = {The comet assay is a commonly used method to determine DNA damage and repair activity in many types of samples. In recent years, the use of the comet assay in human biomonitoring became highly attractive due to its various modified versions, which may be useful to determine individual susceptibility in blood samples. However, in human biomonitoring studies, working with large sample numbers that are acquired over an extended time period requires some additional considerations. One of the most important issues is the storage of samples and its effect on the outcome of the comet assay. Another important question is the suitability of different blood preparations. In this study, we analysed the effect of cryopreservation on DNA damage and repair activity in human blood samples. In addition, we investigated the suitability of different blood preparations. The alkaline and FPG as well as two different types of repair comet assay and an in vitro hydrogen peroxide challenge were applied. Our results confirmed that cryopreserved blood preparations are suitable for investigating DNA damage in the alkaline and FPG comet assay in whole blood, buffy coat and PBMCs. Ex vivo hydrogen peroxide challenge yielded its optimal effect in isolated PBMCs. The utilised repair comet assay with either UVC or hydrogen peroxide-induced lesions and an aphidicolin block worked well in fresh PBMCs. Cryopreserved PBMCs could not be used immediately after thawing. However, a 16-h recovery with or without mitotic stimulation enabled the application of the repair comet assay, albeit only in a surviving cell fraction.},
  language  = {en}
}
@article{DischingerHeckelBischleretal.2021,
  author    = {Dischinger, Ulrich and Heckel, Tobias and Bischler, Thorsten and Hasinger, Julia and K{\"o}nigsrainer, Malina and Schmitt-B{\"o}hrer, Angelika and Otto, Christoph and Fassnacht, Martin and Seyfried, Florian and Hankir, Mohammed Khair},
  title     = {Roux-en-Y gastric bypass and caloric restriction but not gut hormone-based treatments profoundly impact the hypothalamic transcriptome in obese rats},
  series = {Nutrients},
  volume    = {14},
  journal   = {Nutrients},
  number    = {1},
  issn      = {2072-6643},
  doi       = {10.3390/nu14010116},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252392},
  year      = {2021},
  abstract  = {Background: The hypothalamus is an important brain region for the regulation of energy balance. Roux-en-Y gastric bypass (RYGB) surgery and gut hormone-based treatments are known to reduce body weight, but their effects on hypothalamic gene expression and signaling pathways are poorly studied. Methods: Diet-induced obese male Wistar rats were randomized into the following groups: RYGB, sham operation, sham + body weight-matched (BWM) to the RYGB group, osmotic minipump delivering PYY3-36 (0.1 mg/kg/day), liraglutide s.c. (0.4 mg/kg/day), PYY3-36 + liraglutide, and saline. All groups (except BWM) were kept on a free choice of high- and low-fat diets. Four weeks after interventions, hypothalami were collected for RNA sequencing. Results: While rats in the RYGB, BWM, and PYY3-36 + liraglutide groups had comparable reductions in body weight, only RYGB and BWM treatment had a major impact on hypothalamic gene expression. In these groups, hypothalamic leptin receptor expression as well as the JAK-STAT, PI3K-Akt, and AMPK signaling pathways were upregulated. No significant changes could be detected in PYY3-36 + liraglutide-, liraglutide-, and PYY-treated groups. Conclusions: Despite causing similar body weight changes compared to RYGB and BWM, PYY3-36 + liraglutide treatment does not impact hypothalamic gene expression. Whether this striking difference is favorable or unfavorable to metabolic health in the long term requires further investigation.},
  language  = {en}
}
@article{HankirSeyfriedSchellingeretal.2021,
  author    = {Hankir, Mohammed K. and Seyfried, Florian and Schellinger, Isabel N. and Schlegel, Nicolas and Arora, Tulika},
  title     = {Leaky gut as a potential culprit for the paradoxical dysglycemic response to gastric bypass-associated ileal microbiota},
  series = {Metabolites},
  volume    = {11},
  journal   = {Metabolites},
  number    = {3},
  issn      = {2218-1989},
  doi       = {10.3390/metabo11030153},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-234085},
  year      = {2021},
  abstract  = {Altered host-intestinal microbiota interactions are increasingly implicated in the metabolic benefits of Roux-en-Y gastric bypass (RYGB) surgery. We previously found, however, that RYGB-associated ileal microbiota can paradoxically impair host glycemic control when transferred to germ-free mice. Here we present complementary evidence suggesting that this could be due to the heightened development of systemic endotoxemia. Consistently, application of ileal content from RYGB-treated compared with sham-operated rats onto Caco-2 cell monolayers compromised barrier function and decreased expression of the barrier-stabilizing proteins claudin-4 and desmoglein-2. Our findings raise the possibility that RYGB-associated ileal microbiota produce and release soluble metabolites which locally increase intestinal permeability to promote systemic endotoxemia-induced insulin resistance, with potential implications for the treatment of RYGB patients who eventually relapse onto type 2 diabetes.},
  language  = {en}
}
@article{MetznerHerzogHeckeletal.2022,
  author    = {Metzner, Valentin and Herzog, Gloria and Heckel, Tobias and Bischler, Thorsten and Hasinger, Julia and Otto, Christoph and Fassnacht, Martin and Geier, Andreas and Seyfried, Florian and Dischinger, Ulrich},
  title     = {Liraglutide + PYY\(_{3-36}\) combination therapy mimics effects of Roux-en-Y bypass on early NAFLD whilst lacking-behind in metabolic improvements},
  series = {Journal of Clinical Medicine},
  volume    = {11},
  journal   = {Journal of Clinical Medicine},
  number    = {3},
  issn      = {2077-0383},
  doi       = {10.3390/jcm11030753},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-255244},
  year      = {2022},
  abstract  = {Background: Treatment options for NAFLD are still limited. Bariatric surgery, such as Roux-en-Y gastric bypass (RYGB), has been shown to improve metabolic and histologic markers of NAFLD. Glucagon-like-peptide-1 (GLP-1) analogues lead to improvements in phase 2 clinical trials. We directly compared the effects of RYGB with a treatment using liraglutide and/or peptide tyrosine tyrosine 3-36 (PYY\(_{3-36}\)) in a rat model for early NAFLD. Methods: Obese male Wistar rats (high-fat diet (HFD)-induced) were randomized into the following treatment groups: RYGB, sham-operation (sham), liraglutide (0.4 mg/kg/day), PYY\(_{3-36}\) (0.1 mg/kg/day), liraglutide+PYY\(_{3-36}\), and saline. After an observation period of 4 weeks, liver samples were histologically evaluated, ELISAs and RNA sequencing + RT-qPCRs were performed. Results: RYGB and liraglutide+PYY\(_{3-36}\) induced a similar body weight loss and, compared to sham/saline, marked histological improvements with significantly less steatosis. However, only RYGB induced significant metabolic improvements (e.g., adiponectin/leptin ratio 18.8 ± 11.8 vs. 2.4 ± 1.2 in liraglutide+PYY\(_{3-36}\)- or 1.4 ± 0.9 in sham-treated rats). Furthermore, RNA sequencing revealed a high number of differentially regulated genes in RYGB treated animals only. Conclusions: The combination therapy of liraglutide+PYY\(_{3-36}\) partly mimics the positive effects of RYGB on weight reduction and on hepatic steatosis, while its effects on metabolic function lack behind RYGB.},
  language  = {en}
}
@article{BankogluArnoldHeringetal.2018,
  author    = {Bankoglu, Ezgi Eyluel and Arnold, Charlotte and Hering, Ilona and Hankir, Mohammed and Seyfried, Florian and Stopper, Helga},
  title     = {Decreased chromosomal damage in lymphocytes of obese patients after bariatric surgery},
  series = {Scientific Reports},
  volume    = {8},
  journal   = {Scientific Reports},
  number    = {11195},
  doi       = {10.1038/s41598-018-29581-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177090},
  year      = {2018},
  abstract  = {The number of bariatric surgeries being performed worldwide has markedly risen. While the improvement in obesity-associated comorbidities after bariatric surgery is well-established, very little is known about its impact on cancer risk. The peripheral lymphocyte micronucleus test is a widely used method for the monitoring of chromosomal damage levels in vivo, and micronucleus frequency positively correlates with cancer risk. Therefore, the aim of this study was to compare the micronucleus frequency before and after bariatric surgery in obese subjects. Peripheral blood mononuclear cells were collected from 45 obese subjects before and at two time-points after bariatric surgery (6 and 12 months) to assess spontaneous micronucleus frequency. Consistent with the increased cancer risk previously shown, bariatric surgery-induced weight loss led to a significant reduction in lymphocyte micronucleus frequency after 12 months. Interestingly, comorbidities such as type 2 diabetes mellitus and metabolic syndrome further seemed to have an impact on the lymphocyte micronucleus frequency. Our findings may indicate a successful reduction of cancer risk in patients following weight loss caused by bariatric surgery.},
  language  = {en}
}