Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Walter J. Atwood. Includes bibliographical references (leaves 27-44, 62-68, 92-93, 109-111, 120-122). Also available online.

Productive infection of mouse cells with polyoma virus yields mainly two types of particles: Complete virions and empty capsids. Empty polyoma capsids have been shown to be capable of interacting with DNA, in vitro, to form what has been referred to as polyoma-like particles (PLP). The particles are stable in high concentrations of salt and contain DNA protected by the capsid against the action of pancreatic DNase. The development of PLP into a gene transfer vehicle is the subject of the investigations described in the present dissertation. The approach has been to first, characterize the process of PLP formation and second, determine whether the genetic information contained in a specific DNA fragment and assembled into PLP in vitro can be transferred to cells and subsequently be expressed. In terms of PLP characteristics, the experimental results described in this dissertation show that the DNA extracted from PLP is heterogeneous in size. It has a mean molecular weight of 1.2 x 10⁶ with a standard deviation of ±0.5 x 10⁶. In addition, analysis of PLP DNA with restriction endonucleases revealed that a specific primary sequence or higher order structure is not required for PLP formation. Either linear, circular or supercoiled polyoma DNA, as well as, single-stranded DNA, rRNA and the synthetic homopolymers poly(dA).poly(dT) and poly(dG).poly(dC) can be used for PLP formation. Transfer of genetic information by PLP has been accomplished by using a restriction fragment containing the transforming sequences of polyoma DNA as a model gene. This fragment of polyoma DNA, which consists of 1,831 base pairs (approximately 1.2 x 10⁶ daltons) and extends clockwise from the BclI site to the EcoRI site on the conventional polyoma map, causes the induction of the transformed phenotype in rat cells grown in culture. Infection of rat F111 cells by PLP, containing this DNA fragment, results in DNA-mediated oncogenic transformation of the cells as indicated by the formation of dense foci. This gene transfer activity of PLP is shown to be 50 to 150 times more efficient than the widely used calcium phosphate coprecipitation method of introducing DNA into mammalian cells.

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Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Walter J. Atwood. Includes bibliographical references (leaves 39-52, 77-82, 107-111, 131-136, 160-165). Also available online.

Thesis (M. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Merkel cell polyomavirus (MCPyV) is an oncogenic virus exist in about 80% of Merkel Cell Carcinoma (MCC), an aggressive human skin cancer. Evidence of MCPyV existing in other kind of skin neoplasms such as cutaneous squamous cell carcinomas (SCCs) has been reported. Since the major type of cervical cancer is SCCs, MCPyV may be associated with cervical cancer tumorigenesis. A Japanese research group has documented the presence of MCPyV DNA in both cervical SCCs and cervical adenocarcinomas (ACs) from Japanese patients. Nevertheless, the association between MCPyV and cervical cancer remains inconclusive and the prevalence of MCPyV in cervical cancer may show demographic variation. This study is aimed to examine whether MCPyV is present in some of the most common gynaecological cancers, namely cervical cancer, ovarian cancer, endometrial cancer, and gestational choriocarcinoma, in Hong Kong patients. Genomic DNA was obtained from 50 cases of cervical cancer, 20 cases of ovarian cancer, and 35 common gynaecological cancers cell lines. Genomic DNA extracted from four MCC samples were used as positive controls. The integrity of the samples was first checked by β-globin PCR. Detection of MCPyV was then performed by MCPyV Large T antigen (LT-ag) PCR. Our PCR analysis showed that only 1 out of 50 (2%) of the cervical cancer samples was positive for MCPyV DNA. The PCR product was purified and cloned for sequencing analysis. Comparing the LT-ag sequence obtained from the only MCPyV positive cervical cancer with reference sequence and with the MCPyV sequence from one of the control cases revealed the presence of different MCPyV variants in Hong Kong patients. None of the ovarian cancer, endometrial cancer, or choriocarcinoma was positive for MCPyV. Our data did not support the notion that MCPyV is associated with gynaecological malignancies. MCPyV may hence be a fairly specific oncogenic agent for Merkel cell carcinoma. / published_or_final_version / Pathology / Master / Master of Medical Sciences