While the introduction of intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility, concerns have been raised regarding the risk of chromosomal abnormalities in pregnancies derived from ICSI. Studies on sperm from infertile men have suggested that this population may produce higher rates of aneuploid sperm. Thus, we hypothesized that defects in early meiotic events may contribute to both male infertility and the production of aneuploid sperm. We used immunofluorescent techniques to observe the synapsis and recombination of chromosomes during meiosis, and fluorescent in-situ hybridization (FISH) to assess sperm aneuploidy. We analyzed testicular tissue from thirty-one men (10 fertile and 21 infertile men). We observed that ~36% (5/14) of men with impaired spermatogenesis displayed reduced genome-wide recombination. When all men were pooled, we observed an inverse correlation between the frequency of sex chromosome recombination and XY disomy in the sperm. We combined immunofluorescent and FISH techniques to study recombination patterns on chromosomes 13, 18 and 21 in fifteen men (5 fertile and 10 infertile men). Four of the infertile men displayed altered recombination distributions on at least one of the chromosome arms studied. Finally, we examined early meiotic events in two biopsies from an azoospermic t(8;13) carrier. While global recombination rates were not altered, recombination frequencies were reduced specifically on the rearranged chromosomes. Asynapsed quadrivalents were observed in 90% and 87% of pachytene nuclei from the first and second biopsies, respectively, and were frequently associated with the sex chromosomes. BRCA1 and γH2AX, two proteins implicated in meiotic sex chromosome inactivation, localized along asynapsed regions regardless of whether or not they were associated with the sex chromosomes, suggesting that regions of autosomal chromosomes that fail to synapse undergo transcriptional silencing in humans. In summary, we observed that a subset of infertile men display alterations in the number and position of meiotic crossovers, which may contribute to both infertility and an increased risk of sperm aneuploidy. The fidelity of synapsis is also a critical factor in determining the outcome of gametogenesis in humans, as the transcriptional inactivation of asynapsed regions may silence meiotic genes, leading to meiotic arrest and infertility.

Lic.-avh. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 2 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Orientador: Marcio Ajudarte Lopes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-15T17:55:17Z (GMT). No. of bitstreams: 1 Santos-Silva_AlanRoger_D.pdf: 1071923 bytes, checksum: 996d56a5e4895653ebcd0b9e1636e7e2 (MD5) Previous issue date: 2010 / Resumo: Predominantemente, o carcinoma espinocelular (CEC) de boca afeta pacientes idosos e com frequência se desenvolve em associação com o consumo de fumo e álcool. Todavia, evidências científicas têm sugerido o aumento da incidência desta malignidade em pacientes com menos de 40 anos de idade e não expostos aos tradicionais fatores de risco. Informações disponíveis referentes ao câncer de boca em pacientes jovens são escassas e controversas, dificultando a compreensão da patogênese, do comportamento biológico e do prognóstico destes tumores. Como consequência, seu tratamento tem sido baseado principalmente na experiência profissional de cada centro médico. Este trabalho teve como objetivos estudar as características demográficas, os fatores de risco e os aspectos clínicos no momento do diagnóstico, além do perfil biológico de CECs de língua em pacientes com até 40 anos. Foi realizada uma análise retrospectiva multiinstitucional a fim de se investigar gênero, cor da pele, consumo de tabaco e álcool, tamanho dos tumores, metástase regional e à distância, diferenciação histológica e ploidia do DNA dos tumores por meio de citometria por imagem. Os resultados mostraram que tumores em pacientes jovens foram frequentemente detectados em mulheres e pacientes não fumantes e não etilistas, enquanto em pacientes idosos foram detectados, predominantemente, em homens fumantes e etilistas. Além disso, constatou-se que CECs de língua em jovens não se distinguem quanto ao tamanho, a metástases regionais ou à distância e nem quanto ao grau de diferenciação histológica quando comparados com idosos. Ressalta-se, entretanto, que tumores em jovens apresentaram maiores incidências de aneuploidia, tetraploidia e de outros parâmetros de anormalidades da ploidia do DNA. Concluindo, pacientes jovens com CEC de língua apresentaram perfil clínico e biológico peculiares, favorecendo a hipótese de que pacientes jovens com CEC de boca possuem instabilidade genômica aumentada e indicando uma possível natureza genética diferente entre os CECs de língua de jovens e de idosos / Abstract: Oral squamous cell carcinoma (SCC) predominately affects elderly patients and frequently develops in association with tobacco and alcohol consumption. However, an increasing of this malignant disease has been observed in patients younger than 40 years of age, who are not exposed to the traditional risk factors. Data regarding oral cancer in young patients are scarce and controversial, making the determination of the pathogenesis, biological behaviour and prognosis of these tumours difficult. As a consequence, treatment has been mainly based on the professional experience of each medical centre. The aims of this work were to study demographic features, risk factors and clinical aspects at the moment of diagnosis as well as the biologic profile of patients of less than 40 years of age with tongue SCC. A multi-centre retrospective analysis was performed to investigate gender, race, tobacco consumption and alcohol intake, size of the tumour, regional and distant metastasis, histological differentiation and DNA ploidy of tumours through image cytometry. Tumours in young patients were frequently detected in females and nonsmoking and non-drinking patients while older patients were predominantly smoking and drinking males. In addition, tongue SCC in young patients did not differ in size, regional and distant metastasis or tumour grade of differentiation when compared to those in older patients. This study highlighted that tumours from young patients presented higher incidences of aneuploidy, tetraploidy and other parameters related to DNA ploidy abnormalities. In conclusion, young patients with tongue SCC presented a distinct clinical and biological profile, favouring the hypothesis that young patients with oral SCC may have an increased genomic instability and indicating the possibility of underlying genetic differences between TSCC in young and older patients / Doutorado / Patologia / Doutor em Estomatopatologia

Abstract The influence of the X and Y chromosomes on the size and shape of the dental arches and occlusion as well as on craniofacial cephalometric dimensions, angles and dimensional ratios is studied. The material consists of Finnish patients with sex chromosome aneuploidies and normal population controls from the "Kvantti Study" series, which was collected in the 1970's and 1980's at the Institute of Dentistry, University of Turku. The patients are five individuals with complete testicular feminization (CTF), eight 47,XYY males, and fourteen 45,X/46,XX females. The controls are population female and male controls, as well as five first degree relatives of the individuals with CTF, three of the 47,XYY males and nine of the 45,X/46,XX females studied. Dental arch dimensions and occlusion as well as craniofacial cephalometric dimensions, angles and dimensional ratios are measured from dental study casts and standardized lateral cephalograms. The results show that the presence of the Y chromosome in 46,XY females and the supernumerary Y chromosomal gene(s) in 47,XYY males result in the enlargement of the dental arches and craniofacial dimensions without substantial effects on dimensional ratios and plane angles, but with special influence on the growth of the mandibular corpus. The reduction of X chromosomal genetic material in 45,X/46,XX females results in the reduction of craniofacial dimensions, affecting dimensional ratios and especially plane angles of the cranial base.

While the introduction of intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility, concerns have been raised regarding the risk of chromosomal abnormalities in pregnancies derived from ICSI. Studies on sperm from infertile men have suggested that this population may produce higher rates of aneuploid sperm. Thus, we hypothesized that defects in early meiotic events may contribute to both male infertility and the production of aneuploid sperm. We used immunofluorescent techniques to observe the synapsis and recombination of chromosomes during meiosis, and fluorescent in-situ hybridization (FISH) to assess sperm aneuploidy. We analyzed testicular tissue from thirty-one men (10 fertile and 21 infertile men). We observed that ~36% (5/14) of men with impaired spermatogenesis displayed reduced genome-wide recombination. When all men were pooled, we observed an inverse correlation between the frequency of sex chromosome recombination and XY disomy in the sperm. We combined immunofluorescent and FISH techniques to study recombination patterns on chromosomes 13, 18 and 21 in fifteen men (5 fertile and 10 infertile men). Four of the infertile men displayed altered recombination distributions on at least one of the chromosome arms studied. Finally, we examined early meiotic events in two biopsies from an azoospermic t(8;13) carrier. While global recombination rates were not altered, recombination frequencies were reduced specifically on the rearranged chromosomes. Asynapsed quadrivalents were observed in 90% and 87% of pachytene nuclei from the first and second biopsies, respectively, and were frequently associated with the sex chromosomes. BRCA1 and γH2AX, two proteins implicated in meiotic sex chromosome inactivation, localized along asynapsed regions regardless of whether or not they were associated with the sex chromosomes, suggesting that regions of autosomal chromosomes that fail to synapse undergo transcriptional silencing in humans. In summary, we observed that a subset of infertile men display alterations in the number and position of meiotic crossovers, which may contribute to both infertility and an increased risk of sperm aneuploidy. The fidelity of synapsis is also a critical factor in determining the outcome of gametogenesis in humans, as the transcriptional inactivation of asynapsed regions may silence meiotic genes, leading to meiotic arrest and infertility. / Medicine, Faculty of / Obstetrics and Gynaecology, Department of / Graduate

The MAP kinase pathway is well known for its key roles in regulating cell proliferation and cell cycle progression. MAP kinases have also been implicated in mitotic functions, however these functions are less-well understood. Recent studies from our laboratory used Xenopus egg extracts to identify B-Raf as an essential activator of the MAPK cascade during mitosis. Therefore, the first objective of my dissertation research was to determine if B-Raf has functional significance during mitosis in human somatic cells. Using RNA interference against B-Raf and various immunofluorescence techniques, I show that B-Raf: (1) localizes to and is phosphorylated at a key mitotic structure, (2) is critical for proper mitotic spindle assembly and chromatin congression, (3) is important for the engagement of microtubules with kinetochores during mitosis, and (4) is necessary for activation of the spindle assembly checkpoint. It has been demonstrated that B-Raf is a prominent oncogene, constitutively activated in the vast majority of melanomas and other cancers. I hypothesized that oncogenic B-Raf expression perturbs mitosis and causes aneuploidy. First, we show that oncogenic B-Raf expression correlates with mitotic abnormalities in human melanoma cells and that spindle defects are induced when oncogenic B-Raf is ectopically expressed. Further, using FISH and karyotype analysis, I demonstrate that oncogenic B-Raf drives aneuploidy and chromosome instability in primary, immortalized, and tumor cells. In summary, my dissertation studies elucidate novel roles for B-Raf in mammalian mitosis. In addition, my studies show for the first time that oncogenic B-Raf disrupts mitosis causing chromosomal instability. I propose that oncogenic B-Raf-induced chromosome instability contributes to tumorigenesis.

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