published_or_final_version / Medicine / Master / Doctor of Medicine

Thesis (M.A.). / Written for the Faculty of Religious Studies [with a specialization in Biomedical Ethics]. Title from title page of PDF (viewed 2008/07/28). Includes bibliographical references.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

No description available.

Thesis (M.S.)--Case Western Reserve University, 2009. / [School of Medicine] Department of Genetic Counseling. Includes bibliographical references.

Assisted reproduction technology is increasingly used for treatment of couples with subfertility. These women are usually of more advanced maternal age and carry a higher risk of fetal Down syndrome. Results from early publications showed that biochemical markers for screening of fetal Down syndrome in the second trimester were different between pregnancies from in vitro fertilization (IVF) and natural conception. This could potentially increase the false positive rate and result in unnecessary invasive diagnostic procedures. Questions were raised as to whether the alterations were related to ovarian stimulation. This laid the fundamentals of a series of studies presented in this thesis with an aim to address the variations in the concentrations of markers of fetal Down syndrome and the fetal growth profile of pregnancies conceived following different assisted reproduction treatments. Studies were conducted on maternal serum and amniotic fluid alpha fetoprotein (AFP) and human chorionic gonadotrophin (hCG) in the second trimester in pregnancies conceived by assisted reproduction. A reduced level of AFP in maternal serum in pregnancies with fresh embryos together with an elevated level of hCG in both maternal serum and amniotic fluid in pregnancies with frozen thawed embryos were found. This pioneer piece of data showing the raised hCG in frozen thawed embryo pregnancies with unstimulated treatment cycles spoke against the ovarian driven hypothesis, but suggested placental dysfunction be a possible underlying pathophysiology. For markers adopted in the first trimester, the level of pregnancy associated protein A (PAPP-A) was significantly reduced in pregnancies from assisted reproduction. The data on free βhCG was heterogeneous. Apart from biochemical markers, the nuchal translucency was also increased in these singleton pregnancies but not in dichorionic twins. As the direction of deviations of these markers in unaffected pregnancies from assisted reproduction resembled those observed in pregnancies affected by Down syndrome, appropriate adjustment was necessary to reduce the false positive rate for these women. Altered biochemical markers, notably a low PAPP-A level, were also associated with adverse obstetric outcomes. The changes observed in pregnancies from assisted reproduction might be a manifestation of an intrinsic placental insufficiency or fetal developmental delay. A longitudinal study was performed to examine the intrauterine fetal growth profile in these pregnancies. The rate of increment in the mean sac size, which could represent an adaptive compensatory mechanism, was significantly greater in pregnancies from assisted reproduction compared to natural conception. We concluded that pregnancies conceived after assisted reproduction technology were different from pregnancies from natural conception in terms of the concentrations of biochemical and ultrasound markers of Down syndrome. Due to the wide variation in treatment protocols and patients’ background demographics, the exact underlying pathophysiology might be difficult to be explored. Couples undergoing assisted reproduction treatment should be counseled on the increased risk of adverse pregnancy course and perinatal outcome. / published_or_final_version / Medicine / Master / Doctor of Medicine

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-94).

Circulating RNA offers a new detection approach for non-invasive diagnosis. Over the past few years, much effort has been spent on the investigation of possible detection of circulating RNA in plasma. In this thesis, we aim to quantify and characterize cell-free RNA in plasma, and investigate the possibility of using circulating fetal RNA in maternal plasma for non-invasive prenatal diagnosis or monitoring. / In the first part of the thesis, the particle-associated nature of circulating RNA was investigated. Quantitative real-time reverse-transcriptase polymerase chain reaction was developed to measure circulating RNA in healthy individuals and hepatocellular carcinoma (HCC) patients. By subjecting plasma samples to filtration and ultracentrifugation, the presence of both particle-associated and non-particle-associated mRNA species was demonstrated in human plasma. In HCC patents, both the circulating particle- and non-particle-associated plasma RNA concentrations were increased. / The discovery of circulating nucleic acids in plasma and serum has led to the development of numerous promising non-invasive diagnostic tests. The initial non-invasive tests mainly target circulating DNA species. For prenatal diagnosis, circulating fetal DNA in maternal plasma has been utilized for the non-invasive determination of a number of fetal genetic traits. However, as fetal and maternal DNA species co-exist in maternal plasma, these DNA based diagnostic applications depend largely on the use of genetic markers that could discriminate between fetal and maternal DNA, such as the Y chromosome of a male fetus. Thus, a particular DNA marker could only be used in a proportion of pregnancies. This limitation has prompted a quest to develop new fetal nucleic acid markers that are independent of sex or polymorphism and that can be used in all pregnancies. / The existence of circulating RNA is an extraordinary finding because RNA is more labile than DNA and ribonuclease is known to be present in blood. The second study of the thesis reveals that circulating RNA is surprisingly stable under different preanalytical situations. This information has made the study of circulating RNA simpler and more practical for clinical uses. / The third part of this thesis aims at detecting circulating fetal RNA in the plasma of pregnant women. We showed that two placental-derived mRNA species, namely those transcribed from the genes coding for human placental lactogen (hPL) and the beta-subunit of human chorionic gonadotropin (betahCG), are readily detectable in maternal plasma. (Abstract shortened by UMI.) / Tsui Bo Yin. / "May 2005." / Adviser: Y. M. Dennis Lo. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0074. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 166-189). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.