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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Changes of bivalent chromatin coincide with increased expression of developmental genes in cancer

Bernhart, Stephan H., Kretzmer, Helene, Holdt, Lesca M., Jühling, Frank, Ammerpohl, Ole, Bergmann, Anke K., Northoff, Bernd H., Doose, Gero, Siebert, Reiner, Stadler, Peter F., Hoffmann, Steve 12 December 2016 (has links) (PDF)
Bivalent (poised or paused) chromatin comprises activating and repressing histone modifications at the same location. This combination of epigenetic marks at promoter or enhancer regions keeps genes expressed at low levels but poised for rapid activation. Typically, DNA at bivalent promoters is only lowly methylated in normal cells, but frequently shows elevated methylation levels in cancer samples. Here, we developed a universal classifier built from chromatin data that can identify cancer samples solely from hypermethylation of bivalent chromatin. Tested on over 7,000 DNA methylation data sets from several cancer types, it reaches an AUC of 0.92. Although higher levels of DNA methylation are often associated with transcriptional silencing, counter-intuitive positive statistical dependencies between DNA methylation and expression levels have been recently reported for two cancer types. Here, we re-analyze combined expression and DNA methylation data sets, comprising over 5,000 samples, and demonstrate that the conjunction of hypermethylation of bivalent chromatin and up-regulation of the corresponding genes is a general phenomenon in cancer. This up-regulation affects many developmental genes and transcription factors, including dozens of homeobox genes and other genes implicated in cancer. Thus, we reason that the disturbance of bivalent chromatin may be intimately linked to tumorigenesis.
2

P2Y1 receptor signaling contributes to high salt-induced priming of the NLRP3 inflammasome in retinal pigment epithelial cells

Prager, Philipp, Hollborn, Margrit, Steffen, Anja, Wiedemann, Peter, Kohen, Leon, Bringmann, Andreas 14 December 2016 (has links) (PDF)
Background: Systemic hypertension is a risk factor of age-related macular degeneration (AMD), a chronic inflammatory disease. Acute hypertension is caused by increased extracellular osmolarity after intake of dietary salt (NaCl). We determined in cultured human retinal pigment epithelial (RPE) cells whether high extracellular NaCl alters the gene expression of inflammasome-associated proteins, and whether autocrine/paracrine purinergic (P2) receptor signaling contributes to the NaCl-induced NLRP3 gene expression. Methodology/Principal Findings: Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Gene and protein expression levels were determined with real-time RT-PCR and Western blot analysis, respectively. IL-1β and IL-18 levels were evaluated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) expression was knocked down with siRNA. High extracellular NaCl induced NLRP3 and pro-IL-1β gene expression, while the gene expression of further inflammasome-associated proteins (NLRP1, NLRP2, NLRP6, NLRP7, NLRP12, NLRC4, AIM2, ASC, procaspase-1, pro-IL-18) was not altered or below the detection threshold. The NaCl-induced NLRP3 gene expression was partially dependent on the activities of phospholipase C, IP3 receptors, protein kinase C, the serum and glucocorticoid-regulated kinase, p38 MAPK, ERK1/2, JNK, PI3K, and the transcription factors HIF-1 and NFAT5. Pannexin-dependent ATP release and P2Y1 receptor activation is required for the full induction of NLRP3 gene expression. High NaCl induced a transient increase of the NLRP3 protein level and a moderate NLRP3 inflammasome activation, as indicated by the transient increase of the cytosolic level of mature IL-1β. High NaCl also induced secretion of IL-18. High extracellular NaCl induces priming of the NLRP3 inflammasome in RPE cells, in part via P2Y1 receptor signaling. The inflammasome priming effect of NaCl suggests that high intake of dietary salt may promote local retinal inflammation implicated in the development of AMD.
3

Weight stigma reduction and genetic determinism

Hilbert, Anja January 2016 (has links)
One major approach to weight stigma reduction consists of decreasing beliefs about the personal controllability of—and responsibility for—obesity by educating about its biogenetic causes. Evidence on the efficacy of this approach is mixed, and it remains unclear whether this would create a deterministic view, potentially leading to detrimental side-effects. Two independent studies from Germany using randomized designs with delayed-intervention control groups served to (1) develop and pilot a brief, interactive stigma reduction intervention to educate N = 128 university students on gene × environment interactions in the etiology of obesity; and to (2) evaluate this intervention in the general population (N = 128) and determine mechanisms of change. The results showed (1) decreased weight stigma and controllability beliefs two weeks post-intervention in a student sample; and (2) decreased internal attributions and increased genetic attributions, knowledge, and deterministic beliefs four weeks post-intervention in a population sample. Lower weight stigma was longitudinally predicted by a decrease in controllability beliefs and an increase in the belief in genetic determinism, especially in women. The results underline the usefulness of a brief, interactive intervention promoting an interactionist view of obesity to reduce weight stigma, at least in the short term, lending support to the mechanisms of change derived from attribution theory. The increase in genetic determinism that occurred despite the intervention’s gene × environment focus had no detrimental side-effect on weight stigma, but instead contributed to its reduction. Further research is warranted on the effects of how biogenetic causal information influences weight management behavior of individuals with obesity.
4

Ethyl pyruvate

Debebe, Tewodros, Krüger, Monika, Huse, Klaus, Kacza, Johannes, Mühlberg, Katja, König, Brigitte, Birkenmeier, Gerd January 2016 (has links)
The microbiota has a strong influence on health and disease in humans. A causative shift favoring pathobionts is strongly linked to diseases. Therefore, anti-microbial agents selectively targeting potential pathogens as well as their biofilms are urgently demanded. Here we demonstrate the impact of ethyl pyruvate, so far known as ROS scavenger and antiinflammatory agent, on planktonic microbes and biofilms. Ethyl pyruvate combats preferably the growth of pathobionts belonging to bacteria and fungi independent of the genera and prevailing drug resistance. Surprisingly, this anti-microbial agent preserves symbionts like Lactobacillus species. Moreover, ethyl pyruvate prevents the formation of biofilms and promotes matured biofilms dissolution. This potentially new anti-microbial and anti-biofilm agent could have a tremendous positive impact on human, veterinary medicine and technical industry as well.
5

Ethyl pyruvate combats human leukemia cells but spares normal blood cells

Birkenmeier, Gerd, Hemdan, Nasr Y. A., Kurz, Susanne, Bigl, Marina, Pieroh, Philipp, Debebe, Tewodros, Buchold, Martin, Thieme, Rene, Wichmann, Gunnar, Dehghani, Faramarz January 2016 (has links)
Ethyl pyruvate, a known ROS scavenger and anti-inflammatory drug was found to combat leukemia cells. Tumor cell killing was achieved by concerted action of necrosis/apoptosis induction, ATP depletion, and inhibition of glycolytic and para-glycolytic enzymes. Ethyl lactate was less harmful to leukemia cells but was found to arrest cell cycle in the G0/G1 phase. Both, ethyl pyruvate and ethyl lactate were identified as new inhibitors of GSK-3β. Despite the strong effect of ethyl pyruvate on leukemia cells, human cognate blood cells were only marginally affected. The data were compiled by immune blotting, flow cytometry, enzyme activity assay and gene array analysis. Our results inform new mechanisms of ethyl pyruvate-induced cell death, offering thereby a new treatment regime with a high therapeutic window for leukemic tumors.
6

Comparing performance of modern genotype imputation methods in different ethnicities

Roshyara, Nab Raj, Horn, Katrin, Kirsten, Holger, Ahnert, Peter, Scholz, Markus January 2016 (has links)
A variety of modern software packages are available for genotype imputation relying on advanced concepts such as pre-phasing of the target dataset or utilization of admixed reference panels. In this study, we performed a comprehensive evaluation of the accuracy of modern imputation methods on the basis of the publicly available POPRES samples. Good quality genotypes were masked and re-imputed by different imputation frameworks: namely MaCH, IMPUTE2, MaCH-Minimac, SHAPEIT-IMPUTE2 and MaCH-Admix. Results were compared to evaluate the relative merit of pre-phasing and the usage of admixed references. We showed that the pre-phasing framework SHAPEIT-IMPUTE2 can overestimate the certainty of genotype distributions resulting in the lowest percentage of correctly imputed genotypes in our case. MaCH-Minimac performed better than SHAPEIT-IMPUTE2. Pre-phasing always reduced imputation accuracy. IMPUTE2 and MaCH-Admix, both relying on admixed-reference panels, showed comparable results. MaCH showed superior results if well-matched references were available (Nei’s GST ≤ 0.010). For small to medium datasets, frameworks using genetically closest reference panel are recommended if the genetic distance between target and reference data set is small. Our results are valid for small to medium data sets. As shown on a larger data set of population based German samples, the disadvantage of pre-phasing decreases for larger sample sizes.
7

The stress-strain data of the hip capsule ligaments are gender and side independent suggesting a smaller contribution to passive stiffness

Pieroh, Philipp, Schneider, Sebastian, Lingslebe, Uwe, Sichting, Freddy, Wolfskämpf, Thomas, Josten, Christoph, Böhme, Jörg, Hammer, Niels, Steinke, Hanno January 2016 (has links)
Background: The ligaments in coherence with the capsule of the hip joint are known to contribute to hip stability. Nevertheless, the contribution of the mechanical properties of the ligaments and gender- or side-specific differences are still not completely clear. To date, comparisons of the hip capsule ligaments to other tissues stabilizing the pelvis and hip joint, e.g. the iliotibial tract, were not performed. Materials & Methods: Hip capsule ligaments were obtained from 17 human cadavers (9 females, 7 males, 13 left and 8 right sides, mean age 83.65 ± 10.54 years). 18 iliofemoral, 9 ischiofemoral and 17 pubofemoral ligaments were prepared. Uniaxial stress-strain properties were obtained from the load-deformation curves before the secant elastic modulus was computed. Strain, elastic modulus and cross sections were compared. Results: Strain and elastic modulus revealed no significant differences between the iliofemoral (strain 129.8 ± 11.1%, elastic modulus 48.8 ± 21.4 N/mm2), ischiofemoral (strain 128.7 ± 13.7%, elastic modulus 37.5 ± 20.4 N/mm2) and pubofemoral (strain 133.2 ± 23.7%, elastic modulus 49.0 ± 32.1 N/mm2) ligaments. The iliofemoral ligament (53.5 ± 15.1 mm2) yielded a significantly higher cross section compared to the ischiofemoral (19.2 ± 13.2 mm2) and pubofemoral (15.2 ± 7.2 mm2) ligament. No significant gender- or side-specific differences were determined. A comparison to the published data on the iliotibial tract revealed lower elasticity and less variation in the ligaments of the hip joint.
8

Comparing self-report measures of internalized weight stigma: the weight self-stigma questionnaire versus the weight bias internalization scale

Hübner, Claudia, Schmidt, Ricarda, Selle, Janine, Köhler, Hinrich, Müller, Astrid, de Zwaan, Martin, Hilbert, Anja January 2016 (has links)
Background: Internalized weight stigma has gained growing interest due to its association with multiple health impairments in individuals with obesity. Especially high internalized weight stigma is reported by individuals undergoing bariatric surgery. For assessing this concept, two different self-report questionnaires are available, but have never been compared: the Weight Self-Stigma Questionnaire (WSSQ) and the Weight Bias Internalization Scale (WBIS). The purpose of the present study was to provide and to compare reliability, convergent validity with and predictive values for psychosocial health outcomes for the WSSQ and WBIS. Methods: The WSSQ and the WBIS were used to assess internalized weight stigma in N = 78 prebariatric surgery patients. Further, body mass index (BMI) was assessed and body image, quality of life, self-esteem, depression, and anxiety were measured by well-established self-report questionnaires. Reliability, correlation, and regression analyses were conducted. Results: Internal consistency of the WSSQ was acceptable, while good internal consistency was found for the WBIS. Both measures were significantly correlated with each other and body image. While only the WSSQ was correlated with overweight preoccupation, only the WBIS was correlated with appearance evaluation. Both measures were not associated with BMI. However, correlation coefficients did not differ between the WSSQ and the WBIS for all associations with validity measures. Further, both measures significantly predicted quality of life, self-esteem, depression, and anxiety, while the WBIS explained significantly more variance than the WSSQ total score for self-esteem.
9

Changes of bivalent chromatin coincide with increased expression of developmental genes in cancer

Bernhart, Stephan H., Kretzmer, Helene, Holdt, Lesca M., Jühling, Frank, Ammerpohl, Ole, Bergmann, Anke K., Northoff, Bernd H., Doose, Gero, Siebert, Reiner, Stadler, Peter F., Hoffmann, Steve January 2016 (has links)
Bivalent (poised or paused) chromatin comprises activating and repressing histone modifications at the same location. This combination of epigenetic marks at promoter or enhancer regions keeps genes expressed at low levels but poised for rapid activation. Typically, DNA at bivalent promoters is only lowly methylated in normal cells, but frequently shows elevated methylation levels in cancer samples. Here, we developed a universal classifier built from chromatin data that can identify cancer samples solely from hypermethylation of bivalent chromatin. Tested on over 7,000 DNA methylation data sets from several cancer types, it reaches an AUC of 0.92. Although higher levels of DNA methylation are often associated with transcriptional silencing, counter-intuitive positive statistical dependencies between DNA methylation and expression levels have been recently reported for two cancer types. Here, we re-analyze combined expression and DNA methylation data sets, comprising over 5,000 samples, and demonstrate that the conjunction of hypermethylation of bivalent chromatin and up-regulation of the corresponding genes is a general phenomenon in cancer. This up-regulation affects many developmental genes and transcription factors, including dozens of homeobox genes and other genes implicated in cancer. Thus, we reason that the disturbance of bivalent chromatin may be intimately linked to tumorigenesis.
10

P2Y1 receptor signaling contributes to high salt-induced priming of the NLRP3 inflammasome in retinal pigment epithelial cells

Prager, Philipp, Hollborn, Margrit, Steffen, Anja, Wiedemann, Peter, Kohen, Leon, Bringmann, Andreas January 2016 (has links)
Background: Systemic hypertension is a risk factor of age-related macular degeneration (AMD), a chronic inflammatory disease. Acute hypertension is caused by increased extracellular osmolarity after intake of dietary salt (NaCl). We determined in cultured human retinal pigment epithelial (RPE) cells whether high extracellular NaCl alters the gene expression of inflammasome-associated proteins, and whether autocrine/paracrine purinergic (P2) receptor signaling contributes to the NaCl-induced NLRP3 gene expression. Methodology/Principal Findings: Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Gene and protein expression levels were determined with real-time RT-PCR and Western blot analysis, respectively. IL-1β and IL-18 levels were evaluated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) expression was knocked down with siRNA. High extracellular NaCl induced NLRP3 and pro-IL-1β gene expression, while the gene expression of further inflammasome-associated proteins (NLRP1, NLRP2, NLRP6, NLRP7, NLRP12, NLRC4, AIM2, ASC, procaspase-1, pro-IL-18) was not altered or below the detection threshold. The NaCl-induced NLRP3 gene expression was partially dependent on the activities of phospholipase C, IP3 receptors, protein kinase C, the serum and glucocorticoid-regulated kinase, p38 MAPK, ERK1/2, JNK, PI3K, and the transcription factors HIF-1 and NFAT5. Pannexin-dependent ATP release and P2Y1 receptor activation is required for the full induction of NLRP3 gene expression. High NaCl induced a transient increase of the NLRP3 protein level and a moderate NLRP3 inflammasome activation, as indicated by the transient increase of the cytosolic level of mature IL-1β. High NaCl also induced secretion of IL-18. High extracellular NaCl induces priming of the NLRP3 inflammasome in RPE cells, in part via P2Y1 receptor signaling. The inflammasome priming effect of NaCl suggests that high intake of dietary salt may promote local retinal inflammation implicated in the development of AMD.

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