Universiẗat, Diss., 2005--Kiel.

Universiẗat, Diss., 2002--Kiel.

No description available.

Yes / Aspirin and eicosapentaenoic acid (EPA) reduce colorectal adenomatous polyp risk and affect synthesis of oxylipins including prostaglandin E2. We investigated whether 35 single nucleotide polymorphisms (SNPs) in oxylipin metabolism genes such as cyclooxygenase [PTGS] and lipoxygenase [ALOX], as well as 7 SNPs already associated with colorectal cancer (CRC) risk reduction by aspirin (eg. TP53; rs104522), modified the effects of aspirin and EPA on colorectal polyp recurrence in the randomised 2x2 factorial seAFOod trial. Treatment effects were reported as the incidence rate ratio (IRR) and 95% confidence interval (CI) by stratifying negative binomial and Poisson regression analyses of colorectal polyp risk on SNP genotype. Statistical significance was reported with adjustment for the false discovery rate as the P and q value. Five hundred and forty-two (of 707) trial participants had both genotype and colonoscopy outcome data. Reduction in colorectal polyp risk in aspirin users compared with non-aspirin users was restricted to rs4837960 (PTGS1) common homozygotes (IRR 0.69 [95%CI 0.53,0.90]; q=0.06), rs2745557 (PTGS2) compound heterozygote-rare homozygotes (IRR 0.60 [0.41,0.88]; q=0.06), rs7090328 (ALOX5) rare homozygotes (IRR 0.27 [0.11,0.64]; q=0.05), rs2073438 (ALOX12) common homozygotes (IRR 0.57 [0.41,0.80]; q=0.05), and rs104522 (TP53) rare homozygotes (IRR 0.37 [0.17,0.79]; q=0.06). No modification of colorectal polyp risk in EPA users was observed. In conclusion, genetic variants relevant to the proposed mechanism of action on oxylipins are associated with differential colorectal polyp risk reduction by aspirin in individuals who develop multiple colorectal polyps. SNP genotypes should be considered during development of personalised, predictive models of CRC chemoprevention by aspirin. / Funder(s): Efficacy and Mechanism Evaluation Programme (EME) Award Id(s): NIHR128210. Funder(s): NIHR Senior Investigator grant. Funder(s): Cancer Research UK (CRUK) Award Id(s): C23434/A24939. Funder(s): European Union-BBSRC (UK) Award Id(s): BB/P028233/1.

Colorectal polyp prevention trials (PPTs) are randomized, placebo-controlled clinical trials that evaluate some chemo-preventive agent and include participants who will be followed for at least 3 years to compare the recurrence rates (counts) of adenomas. A large proportion of zero counts will likely be observed in both groups at the end of the observation period. Poisson general linear models (GLMs) are usually employed for estimation of recurrence in PPTs. Other models, including the negative binomial (NB2), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) may be better suited to handle zero-inflation or other forms of overdispersion that are common in count data. A model selection paradigm that determines a statistical approach for choosing the best fitting model for recurrence data is described. An example using a subset from a large Phase III clinical trial indicated that the ZINB model was the best fitting model for the data.

Following colonoscopic polypectomy, US Multisociety Task Force (USMSTF) guidelines stratify patients based on risk of subsequent advanced neoplasia (AN) using number, size, and histology of resected polyps, but have only moderate sensitivity and specificity. We hypothesized that a state-of-the-art statistical prediction model might improve identification of patients at high risk of future AN and address these challenges. Data were pooled from seven prospective studies which had follow-up ascertainment of metachronous AN within 3-5 years of baseline polypectomy (combined n = 8,228). Pooled data were randomly split into training (n = 5,483) and validation (n = 2,745) sets. A prognostic model was developed using best practices. Two risk cut-points were identified in the training data which achieved a 10 percentage point improvement in sensitivity and specificity, respectively, over current USMSTF guidelines. Clinical benefit of USMSTF versus model-based risk stratification was then estimated using validation data. The final model included polyp location, prior polyp history, patient age, and number, size and histology of resected polyps. The first risk cut-point improved sensitivity but with loss of specificity. The second risk cut-point improved specificity without loss of sensitivity (specificity 46.2 % model vs. 42.1 % guidelines, p < 0.001; sensitivity 75.8 % model vs. 74.0 % guidelines, p = 0.64). Estimated AUC was 65 % (95 % CI: 62-69 %). This model-based approach allows flexibility in trading sensitivity and specificity, which can optimize colonoscopy over- versus underuse rates. Only modest improvements in prognostic power are possible using currently available clinical data. Research considering additional factors such as adenoma detection rate for risk prediction appears warranted.

Objetivo do estudo: Estimar a prevalência de lesões malignas e prémalignas nos pólipos endometriais e correlacionar com fatores associados com risco de neoplasia de endométrio. Métodos: Revisados dados sobre características clínicas e resultado anatomopatológico dos pólipos ressecados em histeroscopias cirúrgicas com polipectomia realizados entre janeiro de 2005 e julho de 2013 no Hospital de Clínicas de Porto Alegre (HCPA). Resultados: Incluídas 359 pacientes submetidas a polipectomias histeroscópicas. 87,2% das pacientes apresentaram pólipos benignos e 9,9% apresentaram hiperplasia sem atipias. Pólipos com hiperplasia atýpica corresponderam a 2,6% da amostra, enquanto que adenocarcinoma de endométrio foi encontrado de 0,3% dos casos. Verificou-se correlação de resultado maligno/pré-maligno dos pólipos com idade da paciente, seu status menopausal e a presença de sangramento uterino anormal. Todas as mulheres com resultados malignos/pré-malignos apresentaram sangramento uterino anormal. Observou-se maior frequência de malignidade dos pólipos entre usuárias de tamoxifeno, porém sem significância estatística (p 0,059%). Não houve correlação com hipertensão arterial, diabetes mellitus, obesidade, uso de terapia hormonal, espessura endometrial ou diâmetro do pólipo. Conclusão: A prevalência de lesões malignas/pré-malignas nos pólipos endometriais é baixa, tendo sido nula nas pacientes sem sangramento. Não se recomenda a exérese rotineira dos pólipos em pacientes assintomáticas. / Objective: To estimate the prevalence of malignant and premalignant lesions among endometrial polyps and correlate this prevalence with risk factors for endometrial neoplasms. Methods: Review of clinical and histopathological data on polyps resected during hysteroscopic polypectomies performed from January 2005 through July 2013 at Hospital de Clínicas de Porto Alegre (HCPA), Brazil. Results: The sample comprised 359 patients who underwent hysteroscopic polypectomy. Overall, 87.2% of patients had benign polyps and 9.9% had hyperplasia without atypia. Polyps with atypical hyperplasia were found in 2.6% of patients, and endometrial adenocarcinoma, in 0.3%. Polyp malignancy/premalignancy correlated with patient age, menopausal status, and presence of abnormal uterine bleeding. All women with malignant/premalignant lesions had abnormal uterine bleeding.The rate of polyp malignancy was higher among tamoxifen users, although the difference did not reach statistical significance (p=0.059). There was no correlation with hypertension, diabetes mellitus, obesity, hormone replacement therapy, endometrial thickness, or polyp diameter. Conclusion: The prevalence of malignancy/premalignancy among endometrial polyps is low; no cases were identified in patients without uterine bleeding. Routine excision of asymptomatic polyps cannot be recommended.

Der Synaptonemalkomplex (SC) ist eine hochkonservierte Proteinstruktur. Er weist eine dreiteili-ge, leiterähnliche Organisation auf und ist für die stabile Paarung der homologen Chromosomen während der Prophase der ersten meiotischen Teilung verantwortlich, die auch als Synpase be-zeichnet wird. Fehler während der Synpase führen zu Aneuploidie oder Apoptose der sich entwi-ckelnden Keimzellen. Seit 1956 ist der SC Gegenstand intensiver Forschung. Seine Existenz wurde in zahlreichen Orga-nismen von der Hefe bis zum Menschen beschrieben. Seine Struktur aus zwei parallel verlaufen-den Lateralelementen (LE), die durch eine Vielzahl von sogenannten Transversalfilamenten (TF) verbunden werden und dem Zentralen Element (CE) in der Mitte des SC ist dabei offensichtlich über die Millionen von Jahren der Evolution erhalten geblieben. Einzelne Proteinkomponenten des SC wurden jedoch nur in wenigen Modelorganismen charakterisiert, darunter Saccharomyces cerevisiae, Arabidopsis thaliana, Drosophila melanogaster, Ceanorhabditis elegans und Mus mus-culus. Unerwarteter Weise gelang es bei dieser Charakterisierung nicht, eine evolutionäre Ver-wandtschaft, d.h. eine Homologie zwischen den Proteinsequenzen der verschiedenen SCs nach-zuweisen. Diese Tatsache sprach gegen die grundsätzliche Annahme, dass der SC in der Evolution nur einmal entstanden sei. Diese Arbeit hat sich nun der Aufgabe gewidmet, die Diskrepanz zwischen der hochkonservierten Struktur des SC und seiner augenscheinlich nicht-homologen Proteinzusammensetzung zu lösen. Dabei beschränkt sie sich auf die Analyse des Tierreichs. Es ist die erste Studie zur Evolution des SC in Metazoa und demonstriert die Monophylie der Säuger SC Proteinkomponenten im Tierreich. Die Arbeit zeigt, dass mindestens vier von sieben SC Proteinen der Maus spätestens im letzten gemeinsamen Vorfahren der Gewebetiere (Eumetazoa) enstanden sind und auch damals Teil ei-nes ursprünglichen SC waren, wie er heute in dem Nesseltier Hydra zu finden ist. Dieser SC weist die typische Struktur auf und besitzt bereits alle notwendigen Komponenten, um die drei Domä-nen – LE, TF und CE – zu assemblieren. Darüber hinaus ergaben die einzelnen Phylogenien der verschiedenen SC Proteine der Maus, dass der SC eine sehr dynamische Evolutionsgeschichte durchlaufen hat. Zusätzliche Proteine wurden während der Entstehung der Bilateria und der Wir-beltiere in den SC integriert, während andere ursprüngliche Komponenten möglicherweise Gen-Duplikationen erfuhren bzw. besonders in der Linie der Häutungstiere verloren gingen oder sich stark veränderten. Es wird die These aufgestellt, dass die auf den ersten Blick nicht-homologen SC Proteine der Fruchtfliege und des Fadenwurms tatsächlich doch von den ursprünglichen Prote-inenkomponenten abstammen, sich aber aufgrund der rasanten Evolution der Arthropoden und der Nematoden bis zu deren Unkenntlichkeit diversifizierten. Zusätzlich stellt die Arbeit Hydra als alternatives wirbelloses Modellsystem für die Meiose- und SC-Forschung zu den üblichen Modellen D. melanogaster und C. elegans vor. Die kürzlich gewon-nenen Erkenntnisse über den Hydra SC sowie der Einsatz der Standard-Methoden in diesem Orga-nismus werden in dem abschließenden Kapitel zusammengefasst und diskutiert. / The synaptonemal complex (SC) is a highly conserved structure in sexually reproducing organism. It has a tripartite, ladder-like organization and mediates the stable pairing, called synapsis, of the homologous chromosomes during prophase of meiosis I. Failure in homolog synapsis result in aneuploidy and/or apoptosis of the developing germ cells. Since 1956, the SC is subject of intense research and its presence was described in various species from yeast to human. Its structure was maintained during millions of years of evolution consist-ing of two parallel lateral elements (LEs), joined by numerous transverse filaments (TFs) which run perpendicular to the LEs and an electron dense central element (CE) in the middle of the SC. Individual protein components, however, were characterized only in few available model organ-isms, as for example Saccharomyces cerevisiae, Arabidopsis thaliana, Drosophila melanogaster, Ceanorhabditis elegans and Mus musculus. Rather unexpectedly, these characterizations failed to detect an evolutionary homology between the protein components of the different SCs. This fact challenged the general idea of a single origin of the SC in the evolution of meiosis and sexual reproduction. This thesis now addressed itself to the task to unravel the discrepancy between the high conser-vation of the SC structure and its diverse and apparently non-homologous protein composition, focusing on the animal kingdom. It is the first study dealing with the evolution of the SC in Meta-zoa and demonstrates the monophyly of the mammalian SC components in metazoan species. The thesis demonstrates that at least four out of seven murine SC proteins emerged in Eumeta-zoa at the latest and have been likewise part of an ancient SC as it can be found in the present-day cnidarian species Hydra. This SC displays the common organization and already possesses the minimal protein kit corresponding to the three different structural domains: LEs, TFs and the CE. Additionally, the individual phylogenies of the murine SC proteins revealed the dynamic evolu-tionary history of the ancient SC. Further components were added during the diversification of Bilateria and vertebrates while ancestral proteins likely duplicated in the vertebrate lineage and diversified or got lost in the branch leading to ecdysozoan species. It is hypothesized that the apparently non-homologous SC proteins in D. melanogaster and C. elegans actually do derive from the ancient SC proteins but diversified beyond recognition during the fast evolution of Ar-thropoda and Nematoda. The study proposes Hydra as an alternative invertebrate model system for meiosis and SC re-search to the standard organisms D. melanogaster and C. elegans. Recent results about the cni-darian SC as well as the possible application of standard methods is discussed and summarized in the concluding section.

University, Diss., 2003--Kiel.

University, Diss., 2004--Kiel.