Ulf Geisen

Mr. Ulf Geisen


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 December 2020 in Immunity
Verified
Journal Article
Closed access
JBJoana P. Bernardes
Joana P. Bernardes
NMNeha Mishra
Neha Mishra
FTFlorian Tran
Florian Tran
TBThomas Bahmer
Thomas Bahmer
LBLena Best
Lena Best
JZJohn Ziebuhr
John Ziebuhr

21 January 2015 in International Journal of Cancer
Verified
Journal Article
Open access
PDF file
FGFreya A. Goumas
Freya A. Goumas
RHReinhild Holmer
Reinhild Holmer
JEJan‐Hendrik Egberts
Jan‐Hendrik Egberts
AGArtur Gontarewicz
Artur Gontarewicz
CHCarola Heneweer
Carola Heneweer
HKHolger Kalthoff
Holger Kalthoff
Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal human tumors, with radical surgical resection as the only curative treatment option. However, resection is only possible in a small fraction of patients, and about 80% of the patients develop recurrencies. PDAC development is facilitated by the cytokine interleukin‐6 (IL‐6), which acts via classic and trans‐signaling. Both pathways are inhibited by the anti‐IL‐6‐receptor antibody tocilizumab, whereas the fusion protein sgp130Fc specifically blocks trans‐signaling. Here, we show that conservative or adjuvant therapy with both inhibitors reduces tumor growth in an orthotopic model of human Colo357 cells in SCID/bg mice. In the conservative setting, median primary tumor weight was reduced 2.4‐fold for tocilizumab and 4.4‐fold for sgp130Fc. sgp130Fc additionally led to a decrease in microvessel density, which was not observed with tocilizumab. In the adjuvant therapeutic setting after surgical resection of the primary tumor, treatment with tocilizumab or sgp130Fc decreased the local recurrence rate from 87.5% in the control group to 62.5 or 50%, respectively. Furthermore, the median weight of the local recurrent tumors was clearly diminished, and both inhibitors reduced the number of distant metastases. A significant reduction of tumor weight and metastases—comparable to gemcitabine treatment—was also observed with both inhibitors in another model using the poorly differentiated PancTuI cells. Our findings demonstrate the inhibition of IL‐6 as a new treatment option in PDAC.

6 March 2017 in Journal of Applied Phycology
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Journal Article
Closed access
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MZMarion Zenthoefer
Marion Zenthoefer
UGUlf Geisen
Ulf Geisen
KHKarsten Hofmann-Peiker
Karsten Hofmann-Peiker
MFMarkus Fuhrmann
Markus Fuhrmann
JKJannik Kerber
Jannik Kerber
HKHolger Kalthoff
Holger Kalthoff

14 September 2010 in Journal of Sports Sciences
Verified
Journal Article
Closed access
FDFrank E. Döring
Frank E. Döring
SOSimone Onur
Simone Onur
UGUlf Geisen
Ulf Geisen
MBMarcel R. Boulay
Marcel R. Boulay
LPLouis Perusse
Louis Perusse
CBC. Bouchard
C. Bouchard
Homozygosity for a premature stop codon at amino acid position 577 in the alpha-actinin-3 (ACTN3) gene leads to α-actinin-3 deficiency. This genotype is observed in approximately 18% of Caucasians. The ACTN3 R577X polymorphism has been previously associated with indicators of physical performance in several, but not all, studies. We examined the prevalence of R577X (rs1815739) and two additional haplotype tagging single nucleotide polymorphisms (htSNPs) of the ACTN3 gene (rs1791690 and rs2275998) in the Genathlete study comprising 316 male elite endurance athletes ([Vdot]O2max 79.0 ± 3.5 ml · kg−1 · min−1; mean ± s) from North America, Finland, and Germany and 304 sedentary controls ([Vdot]O2max 40.1 ± 7.0 ml · kg−1 · min−1) matched by country of origin. The distribution of genotype and allele frequencies between the two groups was tested by Pearson chi-square and/or Fischer exact test. The prevalence of the 577X homozygote genotype was similar in endurance athletes and controls (20% and 17.5%, respectively). The resulting odds ratio for endurance performance in 577X homozygotes compared with 577R-allele carriers was 1.24 (95%CI 0.82–1.87, P = 0.3). The genotype distribution of the two htSNPs and haplotype frequencies did not differ significantly between athletes and controls. In conclusion, our findings indicate that ACTN3 R577X and other SNPs in ACTN3 are not genetic determinants of endurance performance in Caucasian males.

20 July 2015 in Marine Drugs
Verified
Journal Article
Open access
PDF file
UGUlf Geisen
Ulf Geisen
MZMarion Zenthoefer
Marion Zenthoefer
Matthias PeippMatthias Peipp
Matthias Peipp
JKJannik Kerber
Jannik Kerber
JPJohannes Plenge
Johannes Plenge
HKHolger Kalthoff
Holger Kalthoff
Pancreatic cancer is one of the most aggressive cancer entities, with an extremely poor 5-year survival rate. Therefore, novel therapeutic agents with specific modes of action are urgently needed. Marine organisms represent a promising source to identify new pharmacologically active substances. Secondary metabolites derived from marine algae are of particular interest. The present work describes cellular and molecular mechanisms induced by an HPLC-fractionated, hydrophilic extract derived from the Baltic brown seaweed Fucus vesiculosus (Fv1). Treatment with Fv1 resulted in a strong inhibition of viability in various pancreatic cancer cell lines. This extract inhibited the cell cycle of proliferating cells due to the up-regulation of cell cycle inhibitors, shown on the mRNA (microarray data) and protein level. As a result, cells were dying in a caspase-independent manner. Experiments with non-dividing cells showed that proliferation is a prerequisite for the effectiveness of Fv1. Importantly, Fv1 showed low cytotoxic activity against non-malignant resting T cells and terminally differentiated cells like erythrocytes. Interestingly, accelerated killing effects were observed in combination with inhibitors of autophagy. Our in vitro data suggest that Fv1 may represent a promising new agent that deserves further development towards clinical application.

19 August 2022 in Journal of Medical Virology
Verified
Journal Article
Open access
UGUlf Geisen
Ulf Geisen
RRRuben Rose
Ruben Rose
FNFranziska Neumann
Franziska Neumann
MCMaria Ciripoi
Maria Ciripoi
LVLena Vullriede
Lena Vullriede
BHBimba Franziska Hoyer
Bimba Franziska Hoyer
The humoral immune response to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccination in patients with chronic inflammatory disease (CID) declines more rapidly with tumor necrosis factor‐α (TNF‐α) inhibition. Furthermore, the efficacy of current vaccines against Omicron variants of concern (VOC) including BA.2 is limited. Alterations within immune cell populations, changes in IgG affinity, and the ability to neutralize a pre‐VOC strain and the BA.2 virus were investigated in these at‐risk patients. Serum levels of anti‐SARS‐CoV‐2 IgG, IgG avidity, and neutralizing antibodies (NA) were determined in anti‐TNF‐α patients (n = 10) and controls (n = 24 healthy individuals; n = 12 patients under other disease‐modifying antirheumatic drugs, oDMARD) before and after the second and third vaccination by ELISA, immunoblot and live virus neutralization assay. SARS‐CoV‐2‐specific B‐ and T cell subsets were analysed by multicolor flow cytometry. Six months after the second vaccination, anti‐SARS‐CoV‐2 IgG levels, IgG avidity and anti‐pre‐VOC NA titres were significantly reduced in anti‐TNF‐α recipients compared to controls (healthy individuals: avidity: p ≤ 0.0001; NA: p = 0.0347; oDMARDs: avidity: p = 0.0012; NA: p = 0.0293). The number of plasma cells was increased in anti‐TNF‐α patients (Healthy individuals: p = 0.0344; oDMARDs: p = 0.0254), while the absolute number of SARS‐CoV‐2‐specific plasma cells 7 days after 2nd vaccination were comparable. Even after a third vaccination, these patients had lower anti‐BA.2 NA titres compared to both other groups. We show a reduced SARS‐CoV‐2 neutralizing capacity in patients under TNF‐α blockade. In this cohort, the plasma cell response appears to be less specific and shows stronger bystander activation. While these effects were observable after the first two vaccinations and with older VOC, the differences in responses to BA.2 were enhanced.