@article{AdolphFleischhackGaabetal.2021, author = {Adolph, Jonas E. and Fleischhack, Gudrun and Gaab, Christine and Mikasch, Ruth and Mynarek, Martin and Rutkowski, Stefan and Sch{\"u}ller, Ulrich and Pfister, Stefan M. and Pajtler, Kristian W. and Milde, Till and Witt, Olaf and Bison, Brigitte and Warmuth-Metz, Monika and Kortmann, Rolf-Dieter and Dietzsch, Stefan and Pietsch, Torsten and Timmermann, Beate and Tippelt, Stephan}, title = {Systemic chemotherapy of pediatric recurrent ependymomas: results from the German HIT-REZ studies}, series = {Journal of Neuro-Oncology}, volume = {155}, journal = {Journal of Neuro-Oncology}, number = {2}, organization = {German GPOH HIT-Network}, issn = {0167-594X}, doi = {10.1007/s11060-021-03867-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-308302}, pages = {193-202}, year = {2021}, abstract = {Purpose Survival in recurrent ependymoma (EPN) depends mainly on the extent of resection achieved. When complete resection is not feasible, chemotherapy is often used to extend progression-free and overall survival. However, no consistent effect of chemotherapy on survival has been found in patients with recurrent EPN. Methods Systemic chemotherapeutic treatment of 138 patients enrolled in the German HIT-REZ-studies was analyzed. Survival depending on the use of chemotherapy, disease-stabilization rates (RR), duration of response (DOR) and time to progression (TTP) were estimated. Results Median age at first recurrence was 7.6 years (IQR: 4.0-13.6). At first recurrence, median PFS and OS were 15.3 (CI 13.3-20.0) and 36.9 months (CI 29.7-53.4), respectively. The Hazard Ratio for the use of chemotherapy in local recurrences in a time-dependent Cox-regression analysis was 0.99 (CI 0.74-1.33). Evaluable responses for 140 applied chemotherapies were analyzed, of which sirolimus showed the best RR (50\%) and longest median TTP [11.51 (CI 3.98; 14.0) months] in nine patients, with the strongest impact found when sirolimus was used as a monotherapy. Seven patients with progression-free survival > 12 months after subtotal/no-resection facilitated by chemotherapy were found. No definitive survival advantage for any drug in a specific molecularly defined EPN type was found. Conclusion No survival advantage for the general use of chemotherapy in recurrent EPN was found. In cases with incomplete resection, chemotherapy was able to extend survival in individual cases. Sirolimus showed the best RR, DOR and TTP out of all drugs analyzed and may warrant further investigation.}, language = {en} } @article{AdolfiHerpinRegensburgeretal.2016, author = {Adolfi, Mateus C. and Herpin, Amaury and Regensburger, Martina and Sacquegno, Jacopo and Waxman, Joshua S. and Schartl, Manfred}, title = {Retinoic acid and meiosis induction in adult versus embryonic gonads of medaka}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, doi = {10.1038/srep34281}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147843}, pages = {34281}, year = {2016}, abstract = {In vertebrates, one of the first recognizable sex differences in embryos is the onset of meiosis, known to be regulated by retinoic acid (RA) in mammals. We investigated in medaka a possible meiotic function of RA during the embryonic sex determination (SD) period and in mature gonads. We found RA mediated transcriptional activation in germ cells of both sexes much earlier than the SD stage, however, no such activity during the critical stages of SD. In adults, expression of the RA metabolizing enzymes indicates sexually dimorphic RA levels. In testis, RA acts directly in Sertoli, Leydig and pre-meiotic germ cells. In ovaries, RA transcriptional activity is highest in meiotic oocytes. Our results show that RA plays an important role in meiosis induction and gametogenesis in adult medaka but contrary to common expectations, not for initiating the first meiosis in female germ cells at the SD stage.}, language = {en} } @article{AdolfiHerpinMartinezBengocheaetal.2021, author = {Adolfi, Mateus C. and Herpin, Amaury and Martinez-Bengochea, Anabel and Kneitz, Susanne and Regensburger, Martina and Grunwald, David J. and Schartl, Manfred}, title = {Crosstalk Between Retinoic Acid and Sex-Related Genes Controls Germ Cell Fate and Gametogenesis in Medaka}, series = {Frontiers in Cell and Developmental Biology}, volume = {8}, journal = {Frontiers in Cell and Developmental Biology}, issn = {2296-634X}, doi = {10.3389/fcell.2020.613497}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-222669}, year = {2021}, abstract = {Sex determination (SD) is a highly diverse and complex mechanism. In vertebrates, one of the first morphological differences between the sexes is the timing of initiation of the first meiosis, where its initiation occurs first in female and later in male. Thus, SD is intimately related to the responsiveness of the germ cells to undergo meiosis in a sex-specific manner. In some vertebrates, it has been reported that the timing for meiosis entry would be under control of retinoic acid (RA), through activation of Stra8. In this study, we used a fish model species for sex determination and lacking the stra8 gene, the Japanese medaka (Oryzias latipes), to investigate the connection between RA and the sex determination pathway. Exogenous RA treatments act as a stress factor inhibiting germ cell differentiation probably by activation of dmrt1a and amh. Disruption of the RA degrading enzyme gene cyp26a1 induced precocious meiosis and oogenesis in embryos/hatchlings of female and even some males. Transcriptome analyzes of cyp26a1-/-adult gonads revealed upregulation of genes related to germ cell differentiation and meiosis, in both ovaries and testes. Our findings show that germ cells respond to RA in a stra8 independent model species. The responsiveness to RA is conferred by sex-related genes, restricting its action to the sex differentiation period in both sexes.}, language = {en} } @article{AdolfiDuKneitzetal.2021, author = {Adolfi, Mateus C. and Du, Kang and Kneitz, Susanne and Cabau, C{\´e}dric and Zahm, Margot and Klopp, Christophe and Feron, Romain and Paix{\~a}o, R{\^o}mulo V. and Varela, Eduardo S. and de Almeida, Fernanda L. and de Oliveira, Marcos A. and N{\´o}brega, Rafael H. and Lopez-Roques, C{\´e}line and Iampietro, Carole and Lluch, J{\´e}r{\^o}me and Kloas, Werner and Wuertz, Sven and Schaefer, Fabian and St{\"o}ck, Matthias and Guiguen, Yann and Schartl, Manfred}, title = {A duplicated copy of id2b is an unusual sex-determining candidate gene on the Y chromosome of arapaima (Arapaima gigas)}, series = {Scientific Reports}, volume = {11}, journal = {Scientific Reports}, number = {1}, doi = {10.1038/s41598-021-01066-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265672}, year = {2021}, abstract = {Arapaima gigas is one of the largest freshwater fish species of high ecological and economic importance. Overfishing and habitat destruction are severe threats to the remaining wild populations. By incorporating a chromosomal Hi-C contact map, we improved the arapaima genome assembly to chromosome-level, revealing an unexpected high degree of chromosome rearrangements during evolution of the bonytongues (Osteoglossiformes). Combining this new assembly with pool-sequencing of male and female genomes, we identified id2bbY, a duplicated copy of the inhibitor of DNA binding 2b (id2b) gene on the Y chromosome as candidate male sex-determining gene. A PCR-test for id2bbY was developed, demonstrating that this gene is a reliable male-specific marker for genotyping. Expression analyses showed that this gene is expressed in juvenile male gonads. Its paralog, id2ba, exhibits a male-biased expression in immature gonads. Transcriptome analyses and protein structure predictions confirm id2bbY as a prime candidate for the master sex-determiner. Acting through the TGF beta signaling pathway, id2bbY from arapaima would provide the first evidence for a link of this family of transcriptional regulators to sex determination. Our study broadens our current understanding about the evolution of sex determination genetic networks and provide a tool for improving arapaima aquaculture for commercial and conservation purposes.}, language = {en} } @article{AdolfiCarreiraJesusetal.2015, author = {Adolfi, Mateus C. and Carreira, Ana C. O. and Jesus, L{\´a}zaro W. O. and Bogerd, Jan and Funes, Rejane M. and Schartl, Manfred and Sogayar, Mari C. and Borella, Maria I.}, title = {Molecular cloning and expression analysis of dmrt1 and sox9 during gonad development and male reproductive cycle in the lambari fish, Astyanax altiparanae}, series = {Reproductive Biology and Endocrinology}, volume = {13}, journal = {Reproductive Biology and Endocrinology}, number = {2}, doi = {10.1186/1477-7827-13-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126486}, year = {2015}, abstract = {Background The dmrt1 and sox9 genes have a well conserved function related to testis formation in vertebrates, and the group of fish presents a great diversity of species and reproductive mechanisms. The lambari fish (Astyanax altiparanae) is an important Neotropical species, where studies on molecular level of sex determination and gonad maturation are scarce. Methods Here, we employed molecular cloning techniques to analyze the cDNA sequences of the dmrt1 and sox9 genes, and describe the expression pattern of those genes during development and the male reproductive cycle by qRT-PCR, and related to histology of the gonad. Results Phylogenetic analyses of predicted amino acid sequences of dmrt1 and sox9 clustered A. altiparanae in the Ostariophysi group, which is consistent with the morphological phylogeny of this species. Studies of the gonad development revealed that ovary formation occurred at 58 days after hatching (dah), 2 weeks earlier than testis formation. Expression studies of sox9 and dmrt1 in different tissues of adult males and females and during development revealed specific expression in the testis, indicating that both genes also have a male-specific role in the adult. During the period of gonad sex differentiation, dmrt1 seems to have a more significant role than sox9. During the male reproductive cycle dmrt1 and sox9 are down-regulated after spermiation, indicating a role of these genes in spermatogenesis. Conclusions For the first time the dmrt1 and sox9 were cloned in a Characiformes species. We show that both genes have a conserved structure and expression, evidencing their role in sex determination, sex differentiation and the male reproductive cycle in A. altiparanae. These findings contribute to a better understanding of the molecular mechanisms of sex determination and differentiation in fish.}, language = {en} } @article{AdolfBraunFussetal.2020, author = {Adolf, Christian and Braun, Leah T. and Fuss, Carmina T. and Hahner, Stefanie and K{\"u}nzel, Heike and Handgriff, Laura and Sturm, Lisa and Heinrich, Daniel A. and Schneider, Holger and Bidlingmaier, Martin and Reincke, Martin}, title = {Spironolactone reduces biochemical markers of bone turnover in postmenopausal women with primary aldosteronism}, series = {Endocrine}, volume = {69}, journal = {Endocrine}, number = {3}, issn = {1355-008X}, doi = {10.1007/s12020-020-02348-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-315966}, pages = {625-633}, year = {2020}, abstract = {Context Primary aldosteronism (PA) is the most frequent form of endocrine hypertension. Besides its deleterious impact on cardiovascular target organ damage, PA is considered to cause osteoporosis. Patients and methods We assessed bone turnover in a subset of 36 postmenopausal women with PA. 18 patients had unilateral PA and were treated by adrenalectomy, whereas 18 patients had bilateral PA and received mineralocorticoid receptor antagonist (MRA) therapy respectively. 18 age- and BMI-matched females served as controls. To estimate bone remodeling, we measured the bone turnover markers intact procollagen 1 N-terminal propeptide, bone alkaline phosphatase, osteocalcin and tartrate resistant acid phosphatase 5b in plasma by chemiluminescent immunoassays at time of diagnosis and one year after initiation of treatment. Study design Observational longitudinal cohort study. Setting Tertiary care hospital. Results Compared with controls, patients with PA had mildly elevated osteocalcin at baseline (p = 0.013), while the other bone markers were comparable between both groups. There were no differences between the unilateral and the bilateral PA subgroup. One year after initiation of MRA treatment with spironolactone bone resorption and bone formation markers had significantly decreased in patients with bilateral PA. In contrast, patients adrenalectomized because of unilateral PA showed no significant change of bone turnover markers. Conclusion This study shows that aldosterone excess in postmenopausal women with PA is not associated with a relevant increase of bone turnover markers at baseline. However, we observed a significant decrease of bone markers in patients treated with spironolactone, but not in patients treated by adrenalectomy.}, language = {en} } @phdthesis{Adler2012, author = {Adler, Melanie}, title = {New approaches to improve prediction of drug-induced liver injury}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69512}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {Das h{\"a}ufige Scheitern neuer Arzneistoffkandidaten aufgrund von Lebertoxizit{\"a}t in pr{\"a}klinischen und klinischen Studien stellt ein erhebliches Problem in der Entwicklung von neuen Arzneimitteln dar. Deshalb ist es wichtig, neue Ans{\"a}tze zu entwickeln, mit deren Hilfe unerw{\"u}nschte Wirkungen von Arzneimitteln fr{\"u}her und zuverl{\"a}ssiger erkannt werden k{\"o}nnen. Um die Vorhersage von Lebertoxizit{\"a}t in pr{\"a}klinischen Studien zu verbessern, wurden im Rahmen dieser Arbeit zwei wesentliche Ans{\"a}tze gew{\"a}hlt: 1) die Evaluierung neuer Biomarker, durch die Lebertoxizit{\"a}t zuverl{\"a}ssiger und empfindlicher detektiert werden k{\"o}nnte und 2.) wirkmechanistische Untersuchungen mittels Toxcicogenomics f{\"u}r ein besseres Verst{\"a}ndnis der zugrunde liegenden Mechanismen der Arzneimittel-induzierten Toxizit{\"a}t. Ein Ziel dieser Arbeit war, die F{\"a}higkeit einiger neuer potenzieller Biomarker (NGAL, Thiostatin, Clusterin und PON1) zu bewerten, Arzmeimittel-induzierte Lebertoxizit{\"a}t in Ratten fr{\"u}hzeitig zu erkennen. Die Ergebnisse zeigen, dass PON1 und Clusterin infolge eines durch die verabreichten Arzneistoffkandidaten verursachten Leberschadens nicht konsistent ver{\"a}ndert waren. Diese beiden Marker sind daher, verglichen mit bestehenden klinisch-chemischen Markern, nicht f{\"u}r eine sichere Vorhersage von Arzneistoff-induzierten Lebersch{\"a}den geeignet. Bei Thiostatin und NGAL zeigte sich hingegen ein zeit- und dosisabh{\"a}ngiger Anstieg im Serum und Urin behandelter Tiere. Diese Ver{\"a}nderungen, die gut mit der mRNA Expression im Zielorgan {\"u}bereinstimmten, korrelierten mit dem Schweregrad der Arzneistoff-induzierten Lebersch{\"a}den. Die Analyse mittels ROC zeigte, Thiostatin im Serum, nicht aber NGAL, ein besserer Indikator f{\"u}r Arzneimittel-induzierte hepatobili{\"a}re Sch{\"a}den ist als die routinem{\"a}ßig verwendeten klinische-chemischen Marker, wie z.B. die Leberenzyme ALP, ALT und AST. Thiostatin wird jedoch als Akute-Phase-Protein in einer Vielzahl von Geweben exprimiert und kann somit nicht spezifisch als Lebermarker betrachtet werden. Dennoch zeigen unsere Ergebnisse, dass Thiostatin als sensitiver, minimal-invasiver diagnostischer Marker f{\"u}r Entz{\"u}ndungsprozesse und Gewebesch{\"a}den eine sinnvolle Erg{\"a}nzung in der pr{\"a}klinischen Testung auf Lebertoxizit{\"a}t darstellt. Im zweiten Teil dieser Arbeit wurde mittels RNA-Interferenz das pharmakologische Target des Arzneistoffkandidaten BAY16, der Glukagonrezeptor, auf mRNA-Ebene gehemmt und anhand von Genexpressionsanalysen untersucht, ob die pharmakologisch-bedingte Modulation des Glukagonrezeptors eine Rolle in der Toxizit{\"a}t von BAY16 spielt. Desweiteren sollten diese Arbeiten Aufschluss geben, welche molekularen Ver{\"a}nderungen auf die pharmakologische Wirkung des Arzneistoffs zur{\"u}ckzuf{\"u}hren sind, und daher f{\"u}r den Mechanismus der Toxizit{\"a}t m{\"o}glicherweise wenig relevant sind. W{\"a}hrend BAY16 in Konzentrationen von 75 µM starke zytotoxische Wirkungen aufwies, hatte die siRNA vermittelte Depletion des Glukagonrezeptors keinen Einfluss auf die Vitalit{\"a}t prim{\"a}rer Rattenhepatozyten. Daraus l{\"a}sst sich ableiten, dass die Hepatotoxizi{\"a}t von BAY16 in vitro und in vivo nicht mit der pharmakologischen Modulation des Glukagonrezeptors assoziiert ist. Diese Ergebnisse wurden durch die Tatsache gest{\"u}tzt, dass die meisten der durch BAY16 induzierten Genexpressionsver{\"a}nderungen unabh{\"a}ngig von der pharmakologischen Modulation des Glucagonrezeptors auftraten. Diese beobachteten off-target-Effekte beinhalteten Ver{\"a}nderungen im Fremdstoffmetabolismus, oxidativer Stress, erh{\"o}hte Fetts{\"a}uresynthese und Ver{\"a}nderungen im Cholesterol- und Gallens{\"a}uremetabolismus. Obwohl Ver{\"a}nderungen in diesen molekularen Mechanismen zum Fortschreiten eines Leberschadens beitragen k{\"o}nnen, ist es anhand dieser Daten nicht m{\"o}glich einen eindeutigen Mechanismus f{\"u}r die Toxizit{\"a}t von BAY16 abzuleiten. In dieser Arbeit konnte jedoch gezeigt werden, dass die Anwendung der siRNA-Technologie einen neuen methodischen Ansatz darstellt, um Mechanismen arzneimittelbedingter Toxizit{\"a}t besser verstehen zu k{\"o}nnen.}, subject = {Biomarker}, language = {en} } @phdthesis{Adler2021, author = {Adler, Florian Rudolf}, title = {Electronic Correlations in Two-dimensional Triangular Adatom Lattices}, doi = {10.25972/OPUS-24175}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-241758}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Two-dimensional triangular lattices of group IV adatoms on semiconductor substrates provide a rich playground for the investigation of Mott-Hubbard physics. The possibility to combine various types of adatoms and substrates makes members of this material class versatile model systems to study the influence of correlation strength, band filling and spin-orbit coupling on the electronic structure - both experimentally and with dedicated many-body calculation techniques. The latter predict exotic ground states such as chiral superconductivity or spin liquid behavior for these frustrated lattices, however, experimental confirmation is still lacking. In this work, three different systems, namely the \(\alpha\)-phases of Sn/SiC(0001), Pb/Si(111), and potassium-doped Sn/Si(111) are investigated with scanning tunneling microscopy and photoemission spectroscopy in this regard. The results are potentially relevant for spintronic applications or quantum computing. For the novel group IV triangular lattice Sn/SiC(0001), a combined experimental and theoretical study reveals that the system features surprisingly strong electronic correlations because they are boosted by the substrate through its partly ionic character and weak screening capabilities. Interestingly, the spectral function, measured for the first time via angle-resolved photoemission, does not show any additional superstructure beyond the intrinsic \(\sqrt{3} \times \sqrt{3} R30^{\circ}\) reconstruction, thereby raising curiosity regarding the ground-state spin pattern. For Pb/Si(111), preceding studies have noted a phase transition of the surface reconstruction from \(\sqrt{3} \times \sqrt{3} R30^{\circ}\) to \(3 \times 3\) at 86 K. In this thesis, investigations of the low-temperature phase with high-resolution scanning tunneling microscopy and spectroscopy unveil the formation of a charge-ordered ground state. It is disentangled from a concomitant structural rearrangement which is found to be 2-up/1-down, in contrast to previous predictions. Applying an extended variational cluster approach, a phase diagram of local and nonlocal Coulomb interactions is mapped out. Based on a comparison of theoretical spectral functions with scattering vectors found via quasiparticle interference, Pb/Si(111) is placed in said phase diagram and electronic correlations are found to be the driving force of the charge-ordered state. In order to realize a doped Mott insulator in a frustrated geometry, potassium was evaporated onto the well-known correlated Sn/Si(111) system. Instead of the expected insulator-to-metal transition, scanning tunneling spectroscopy data indicates that the electronic structure of Sn/Si(111) is only affected locally around potassium atoms while a metallization is suppressed. The potassium atoms were found to be adsorbed on empty \(T_4\) sites of the substrate which eventually leads to the formation of two types of K-Sn alloys with a relative potassium content of 1/3 and 1/2, respectively. Complementary measurements of the spectral function via angle-resolved photoemission reveal that the lower Hubbard band of Sn/Si(111) gradually changes its shape upon potassium deposition. Once the tin and potassium portion on the surface are equal, this evolution is complete and the system can be described as a band insulator without the need to include Coulomb interactions.}, subject = {Rastertunnelmikroskopie}, language = {en} } @phdthesis{Adhikari2024, author = {Adhikari, Bikash}, title = {Targeted degradation of Myc-interacting oncoproteins}, doi = {10.25972/OPUS-31732}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-317326}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {The hallmark oncoprotein Myc is a major driver of tumorigenesis in various human cancer entities. However, Myc's structural features make it challenging to develop small molecules against it. A promising strategy to indirectly inhibit the function of Myc is by targeting its interactors. Many Myc-interacting proteins have reported scaffolding functions which are difficult to target using conventional occupancy- driven inhibitors. Thus, in this thesis, the proteolysis targeting chimera (PROTAC) approach was used to target two oncoproteins interacting with Myc which promote the oncogenicity of Myc, Aurora-A and WDR5. PROTACs are bifunctional small molecules that bind to the target protein with one ligand and recruit a cellular E3- ligase with the other ligand to induce target degradation via the ubiquitin- proteasome system. So far, the most widely used E3-ligases for PROTAC development are Cereblon (CRBN) and von Hippel-Lindau tumor suppressor (VHL). Furthermore, there are cases of incompatibility between some E3-ligases and proteins to bring about degradation. Hence there is a need to explore new E3- ligases and a demand for a tool to predict degradative E3-ligases for the target protein in the PROTAC field. In the first part, a highly specific mitotic kinase Aurora-A degrader, JB170, was developed. This compound utilized Aurora-A inhibitor alisertib as the target ligand and thalidomide as the E3-ligase CRBN harness. The specificity of JB170 and the ternary complex formation was supported by the interactions between Aurora-A and CRBN. The PROTAC-mediated degradation of Aurora-A induced a distinct S- phase defect rather than mitotic arrest, shown by its catalytic inhibition. The finding demonstrates that Aurora-A has a non-catalytic role in the S-phase. Furthermore, the degradation of Aurora-A led to apoptosis in various cancer cell lines. In the second part, two different series of WDR5 PROTACs based on two protein- protein inhibitors of WDR5 were evaluated. The most efficient degraders from both series recruited VHL as a E3-ligase and showed partial degradation of WDR5. In addition, the degradation efficiency of the PROTACs was significantly affected by the linker nature and length, highlighting the importance of linker length and composition in PROTAC design. The degraders showed modest proliferation defects at best in cancer cell lines. However, overexpression of VHL increased the degradation efficiency and the antiproliferative effect of the PROTACs. In the last part, a rapamycin-based assay was developed to predict the degradative E3-ligase for a target. The assay was validated using the WDR5/VHL and Aurora- A/CRBN pairs. The result that WDR5 is degraded by VHL but not CRBN and Aurora-A is degraded by CRBN, matches observations made with PROTACs. This technique will be used in the future to find effective tissue-specific and essential E3-ligases for targeted degradation of oncoproteins using PROTACs. Collectively, the work presented here provides a strategy to improve PROTAC development and a starting point for developing Aurora-A and WDR5 PROTACs for cancer therapy.}, subject = {Degradation}, language = {en} } @article{AdeyemoShapiraTombaccinietal.1991, author = {Adeyemo, O. M. and Shapira, S. and Tombaccini, D. and Pollard, H. and Feuerstein, G. and Sir{\´e}n, Anna-Leena}, title = {A goldfish model for evaluation of the neurotoxicit of \(\omega\)-conotoxin GVIA and screening of monoclonal antibodies}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63087}, year = {1991}, abstract = {A Goldfish Model for Evaluation of the Neurotaxicity of \(\omega\)-Conotoxin GVI A and Screening of Monoclonal Antibodies. ADEYEMO, 0. M .. SHAPIRA, S., TOMBACCINI, D., POLLARD, H. 8 .• FEUERSTEIN, G .. AND SIREN, A-L. ( 1991 ). Toxicol. App/. Pharmaco/. 108, 489-496. The neurotoxicity of \(\omega\)-conotoxin (\(\omega\)-CgTx), a potent neuronal voltage-sensitive calcium channel blocker, was measured using a new bioassay. \(\omega\)-CgTx was administered intraperitoneally (ip) to goldfish weighing approximately 1.6 g, and dose-related changes were observed over a 2-hr period. \(\omega\)CgTx induced time- and dose-dependent abnormal swimming behavior (ASB) and mortality. The antitoxin activity of the antiborlies was investigated in vivo by either ( l) preincubation of the antibody with w-CgTx at 4°C overnight, or (2) pretreatment with antibody, 30 min before \(\omega\)CgTx injection in a 10:1 antibody/\(\omega\)-CgTx molar ratio. The LD50 dose of \(\omega\)-CgTx in goldfish was 5 nmol/kg ip, and preincubation of monoclonal antibody (50 nmol/kg ip) with \(\omega\)-CgTx (5 nmol/kg ip) significantly (p < 0.05) reduced mortality. ASB, and toxicity time. The antitoxin activity of the monoclonal antiborlies evidenced in the goldfish bioassay was further tested in the conscious rat. In the rat, the increases in mean arterial pressure and heart rate induced by \(\omega\)-CgTx (0.03 nmol/rat icv) were significantly (p < 0.02 and p < 0.0 l, respectively) attenuated by preincubation of the toxin with the antibody (0.3 nmol/rat). We conclude that the goldfish bioassay provides a simple. accurate, and inexpensive in vivo model for the study of the toxicity of \(\omega\)CgTx}, subject = {Neurobiologie}, language = {en} }