Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvii, 292 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Mihael C. Ostrowski, Dept. of Molecular, Cellular and Developmental Biology. Includes bibliographical references (p. 259-292).

Includes bibliographical references (p. 80-91).

Thesis (Ph. D.)--University of Chicago, Dept. of Pathology, August 2001. / Includes bibliographical references. Also available on the Internet.

Using piezoelectric materials to harvest the energy of vibration is a popular and fast-growing field of study. This report details an attempt to use piezoelectric energy harvesting techniques to support an interesting and engaging lab experience for high school engineering students in which the vibration of musical instruments (specifically drums, for this report) is harnessed to power a string of decorative LEDs. The likelihood of the energy harvesting actually being successful enough to light the LEDs was not known before undertaking this lab, so the goals of the project became twofold: 1. Conduct the experiment from scratch to determine if a substantial amount of energy can be harvested from the instruments (enough to reach the goal of lighting the LEDs), and 2. Identify how this lab experience (or one similar to it, if the goal of lighting the LEDs is unattainable) can be beneficial to high school engineering students. The purpose of this report is to summarize the research that was carried out to harvest energy from drums using piezoelectric technology, and to outline how similar lab exercises can be utilized in the high school engineering classroom setting. / text

The simultaneous phenomena of a shortage in the STEM (Science, Technology, Engineering, and Math) labor force coupled with the growing Latino population in the U.S. dictates a need for higher education institutions to ensure the success of Latino students in the STEM disciplines. Current trends indicate that Latino males are interested in pursuing a STEM major, but are attaining STEM degrees at low rates. Furthermore, prior research has shown that over half of all STEM degree pursuers change majors within the first two years and that the first few weeks of college are critical for Latino students. As such, this dissertation used a qualitative, phenomenological approach to examine the first-semester lived experience of Latino males in the STEM disciplines using a science identity framework. Overall, this study had five major findings. First, the findings from this study challenged the existing science identity framework by emphasizing competence as opposed to recognition. Second, participants considered the importance of having a supportive scientific community within their first semester. At the same time, they also highlighted the competitiveness and exclusivity of the scientific community as a major factor that drew them into pursuing a STEM major. Third, the high-achieving participants in this study stressed the importance of being innovative, thinking out of the box, and connecting patterns in approaching their subject areas. Fourth, students in this study had to negotiate their science identities with other parts of their identities, such as their racial identities, gender identities, religious identities, creative identities, and musical identities. Finally, participants in this study who were enrolled in a critical thinking seminar developed a thorough understanding about science within a broader context, and gained knowledge about how the scientific community interacts with other industries, such as business, law, and politics. Given these findings, this study expanded, challenged, and added to the existing literature about Latino men in the STEM disciplines. / text

A typical clinical cis-diamminedichloroplatinum (II) (cisplatin) dosing regimen consists of repeated cycles of five to seven daily low dose treatments followed by a one to two week recovery period. While effective, this dosing structure results in a prolonged, and sometimes permanent, infertility in men. Undifferentiated spermatogonia, including spermatogonial stem cells (SSCs), are theoretically capable of repopulating the seminiferous tubules after exposure has ceased. It is proposed that an altered spermatogonial environment during recovery from the initial treatment cycle may drive an increase in SSC mitotic cell activity, rendering the SSC pool increasingly susceptible to cisplatin-induced cell death from subsequent cycles. The undifferentiated spermatogonia population and niche of the adult mouse (C57/BL/6J) were examined during the recovery period of a clinically-relevant course of one and two cycles of 2.5 mg/kg/d of intraperitoneal cisplatin and were compared to mice receiving an equivalent cumulative dose in a single cycle (5.0 mg/kg/d) and vehicle treated controls. Histological examination of the testicular epithelium revealed an increase in the disorganization of spermatogenesis correlating with the number of exposure cycles. Quantification of TUNEL positive cells showed an increase in apoptotic germ cells early in the recovery period in mice exposed to cisplatin compared to control animals. Immunohistochemical (IHC) examination of Foxo1 (undifferentiated spermatogonia marker) showed an increase in the undifferentiated spermatogonia population late in the recovery period in mice exposed to one cycle of 2.5 mg/kg/d, but not following two cycles of 2.5 mg/kg/d. Analysis of BrdU incorporation after dosing indicated a decrease in mitotic activity of early germ cells immediately after cisplatin exposure followed by a return to basal levels by the conclusion of the initial recovery period. No such rebound was observed during the second recovery period. IHC investigation of glial cell line-derived neurotrophic factor (GDNF), a recognized SSC niche factor, revealed an increase in production along the basal Sertoli cell membrane throughout the recovery period in all treatment groups. Taken together, these data establish that the impact of cisplatin exposure on the functional stem cell pool and niche correlates with: (1) the number of dosing cycles; (2) mitotic activity of early germ cells; and (3) alterations in the basal Sertoli cell GDNF expression levels after cisplatin-induced testicular injury. / text

published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Neural stem cells (NSCs) are defined as multipotent stem cells. They are able to self-renew and differentiate into mature cells, such as neurons, oligodendrocytes and astrocytes. Neurotoxicity of lead (Pb2+) has been extensively investigated by many previous studies. These studies proved that lead is a potent toxin that affects nervous system, especially children’s brain. However, most of these studies focused on the negative effects of lead on the differentiated or mature cell types in the brains instead of NSCs. The aim of this study was to reveal the effects of Pb2+ on viability, proliferation and differentiation of NSCs derived from the hippocampus of newborn rats aged 7 days and adult rats aged 90 days in vitro. NSCs harvested from the rat hippocampus were cultured in proliferation medium. After 6-8 days, free-floating neurospheres formed. The neurospheres were dissociated and plated onto poly-L-lysine coated 96-well plate and coverslips. Some dissociated cells were characterized by being stained with anti-nestin to show the presence of NSCs. This project was divided into three parts. In the first part, the Passage 2 (P2) cells plated onto 96-well plate were cultured in the proliferation medium with different concentrations of lead acetate (0-200μM) for 48 hours, followed by 3- (4,5-cimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to detect the effects of Pb2+ on the cell viability. In the second part, P2-NSCs plated onto coverslips in wells were cultured in the proliferation medium with different concentrations of lead acetate (0-200μM). Then, 10 μM bromodeoxyuridine (BrdU) was added into the culture medium for additional 24 hours, followed by immunocytochemistry staining with anti-BrdU. In the last part, the dissociated P2-NSCs plated onto coverslips were allowed to grow in the differentiation medium of neurons, astrocytes or oligodendrocytes with different concentrations of lead acetate (0-200μM). After 6 days, immunocytochemistry staining with anti-microtubule-associated protein 2 (anti-MAP2), anti-glial fibrillary acidic protein (anti-GFAP) or anti-RIP was used to detect the differentiation commitment of affected NSCs. Low level of Pb2+ (1-10μM) had no effect on the viability of adult hippocampal neural stem cells (hNSCs). However, Pb2+ exposure at the concentration of 10μM could lead to significant cell death of newborn hNSCs. High level of Pb2+ (50-200μM) caused significant cell death of both newborn and adult hNSCs. Newborn hNSCs were sensitive to Pb2+ toxicity in proliferation assay. Even a low concentration (1μM) of lead could lead to significant inhibition of cell proliferation. High level of Pb2+ (50-200μM) suppressed proliferation of both newborn and adult hNSCs significantly. Moderate to high levels of Pb2+ exposure (50-200μM) significant decreased the percentage of mature neurons cultured from both newborn and adult hNSCs. Furthermore, 10μM or more Pb2+could significantly inhibited the oligodendrocyte differentiation of both newborn and adult hNSCs. However, Pb2+ could also stimulate the astrocyte differentiation of hNSCs. Lead concentrations higher than 10μM and 50μM could respectively lead to a significant increase in the percentage of mature astrocytes differentiated from newborn and adult hNSCs. The data showed that Pb2+ inhibited not only the viability and proliferation of rat hNSCs but also the neuronal and oligodendrocyte differentiation in vitro; moreover activated astrocyte differentiation of the hNSCs of both newborn and adult rats were observed with high concentration of Pb2+ in vitro. Also, it was revealed that the hNSCs of newborn rats were more sensitive than those from adult rats to Pb2+ cytoxicity. / published_or_final_version / Anatomy / Master / Master of Medical Sciences

published_or_final_version / Chinese Medicine / Doctoral / Doctor of Philosophy