Achee
May
Galbreath Murtie
Judge Vaughn
Nicole
L. Achee
Department of Preventive Medicine and Biometrics
Doctor
of Philosophy
2004
Major Advisor: Donald Roberts, Ph.D , Department of Preventive Medicine & Biometrics
Title
of Dissertation: A Study on the Bionomics of Anopheles darlingi Root
(Diptera: Culicidae) in Belize, Central America
ABSTRACT
Interdisciplinary studies were conducted to describe the bionomics of the
malaria vector Anopheles darlingi Root in Belize, Central America. Studies
investigated the following: nightly adult biting patterns; seasonal population
densities; flight behavior patterns; the role of overhanging bamboo in larval
habitat preference; the association between deforestation and bamboo growth;
and the associations between land cover and river characteristics to the distribution
of positive larval habitats.
Results from all-night biting studies show An. darlingi to exhibit a bimodal peak activity pattern with biting continuing throughout the night at similar rates both indoors and outside of an experimental hut (I:O=1.00:0.96). Population studies show An. darlingi to have its densest populations during seasonal transitional months including January and May/July. Results from flight behavior studies of An. darlingi females, using a newly designed portable hut, show the highest recapture rate was made at the 0 M distance (28.9%) from a fixed release point, then declined from 11.6% at 400 M to 5.8% at 800 M.Habitat preference studies indicate that overhanging bamboo is not an An. darlingi breeding site selection criterion. Experimental plots in which bamboo was hung above detritus consistently showed significantly fewer An. darlingi larvae than plots with detritus alone and similar numbers as in open water control plots. Studies combining field mapping with remote sensing along "cleared" (i.e., deforested) and "undisturbed" (i.e., forested) transects within two river systems showed no associations between land cover adjacent to the rivers and bamboo growth. Results were consistent using both SPOT (20-m resolution) and IKONOS (4-m resolution) satellite imagery.
In addition, overhanging bamboo was not the primary contributor to the formation of potential An. darlingi larval habitats formed within a 48-km transect of the Sibun River. Instead, components of trees (i.e., fallen trunks, etc.) were found to be the predominant landscape feature associated with habitat creation. Using IKONOS imagery, no associations were found between the locations of positive habitats and land cover or river characteristics. However, the average distance from detritus mats containing An. darlingi larvae to houses located within a 1,000-m search radius was significantly less than the distance from negative habitats.
Major
Nathan W. Galbreath
Department of Medical and Clinical Psychology
Doctor
of Philosophy
2004
Major Advisor: Tracy Sbrocco, Ph.D , Department of Medical and Clinical Psychology
Dissertation
Title: The Effect of False Physiological Feedback on
Sexual Arousal in Sexually Functional and Dysfunctional Men
ABSTRACT
In the present study, a false feedback paradigm was used to manipulate the experience of seventy-six men to produce a discrepancy between actual and expected sexual performance. Thirty-nine men were diagnosed with male erectile disorder due to psychogenic factors, while the other thirty-seven were sexually functional. Experimental participants were provided with inflated feedback concerning the size of their erections while they viewed an erotic videotape. By examining changes in expectations of sexual performance, confidence, and tumescence over time, the impact of false feedback on sexual function was experimentally evaluated.
It was proposed that inflated feedback would differentially modify cognitive set and penile tumescence in sexually functional and dysfunctional men. Based on prior studies, experimental groups were expected to show decreased erectile response, despite receiving inflated feedback. Functional men were expected to increase expectancies, while those of dysfunctional men were expected to decrease. Furthermore, functional men were expected to regain tumescence with additional exposure to erotica. Dysfunctional men were not expected to restore tumescence. Functionals responded to inflated feedback by increasing their expectancy associated with the feedback itself. While predicted tumescence and confidence did not increase, the functional men believed they experienced larger erections. Dysfunctionals also believed they had larger erections and were more surprised by the inflated score than the functionals. However, dysfunctional men did not increase expectancies or confidence.
The study found limited support for the idea that additional exposure to erotica
restores tumescence. Neither group experienced a decrease in average tumescence,
so there was no loss of tumescence to be “restored.” An unexpected
between-groups difference in speed of sexual response made the data for functional
men uninterpretable. However, inflated feedback appeared to have unexpected
“restorative” effects for dysfunctional men, as they showed no
difference from normals on measures of erectile response. Dysfunctionals that
did not receive feedback demonstrated less tumescence throughout the experimental
manipulation than functional controls. This finding, if replicated, may have
potential as a basis for a new intervention in the treatment of erectile dysfunction.
Nicole
A. Judge
Department of Microbiology and Immunology
Doctor
of Philosophy
2004
Major Advisor: Alison O’Brien, Ph.D , Department of Microbiology & Immunology
Dissertation Title: Toward Development of an Oral, Plant-based Vaccine Against Escherichia coli O157:H7
ABSTRACT
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is the most common infectious cause of bloody diarrhea in the United States, and a sequela of this infection, the hemolytic uremic syndrome (HUS), is the primary cause of acute renal failure in children in the U.S. The majority of U.S. cases of EHEC O157:H7 have occurred as a consequence of ingestion of undercooked, contaminated hamburger or produce and/or water contaminated with bovine manure. Intimin is the primary adhesin of EHEC O157:H7, and is required for colonization of neonatal calves. I hypothesized that an intimin-based vaccination strategy in calves might reduce colonization of cattle with EHEC O157:H7. To test this concept in a small animal model, I developed transgenic tobacco plant cells that expressed the full length or carboxy-terminal portion (Int261) of EHEC O157:H7 intimin and then immunized mice parenterally with intimin expressed from the plant cells, or fed mice the transgenic plant cells, or both. I was able to show that these mice not only generated an intimin-specific mucosal immune response when primed parenterally and boosted orally but also exhibited a reduced duration of EHEC O157:H7 fecal shedding after challenge. These results suggest that transgenic plants are attractive and feasible production and delivery systems for an intimin-based vaccine for cattle, and such a vaccine can reduce the duration of EHEC O157:H7 shedding in a small animal model. In addition, Shiga toxin type 2 (Stx2) is another important EHEC O157:H7 virulence factor that plays a critical role in the development of potentially fatal HUS in humans. I developed a toxoid of Stx2 by making site-directed changes to the nucleotide sequence of the Stx2 A subunit gene that abrogated cytotoxcity in vitro and in vivo. The Stx2 toxoid elicited toxin-neutralizing antibody when parenterally injected in mice. I also optimized both the Stx2 A toxoid subunit and the B subunit for expression in plants and, thus laid the groundwork for future expression of this Stx2 toxoid molecule in plants.
Lisa
M. May
Department of Preventive Medicine and Biometrics
Doctor
of Public Health
2004
Major Advisor: Arthur Lee, Ph.D., Department of Preventive Medicine and Biometrics
Dissertation Title: The Military Deployment Human Exposure Assessment Study (MDHEXAS): Blood and urine exposure biomarkers as environmental surveillance tools for assessing military personnel exposure to chemicals during deployment to Camp McGovern, Bosnia
ABSTRACT
Currently the Department of Defense (DoD) does not use exposure biomarkers to measure environmental exposures to chemicals. Blood and urine exposure biomarkers for volatile organic compounds (VOC), selected heavy metals, depleted uranium (DU), and chemical warfare agents are currently available but have not been field tested or validated in military deployments as a tool to document exposures by the DoD. The Military Deployment Human Exposure Assessment Study, a prospective cohort of 46 soldiers deployed to Bosnia, was designed to validate blood and urine exposure biomarkers as a mechanism to document exposures to these chemicals during military deployments. Blood and urine were collected pre-, during, and post deployment. Standard questionnaire was administered, and environmental and occupational monitoring methods were conducted for comparison to the exposure biomarker results. The urine depleted uranium, blood VOC, urine heavy metals, and blood heavy metals results are compared pre-, during, and post deployment and against standard US reference ranges for the same compounds. The results of the study indicate that natural uranium and styrene environmental exposures increased during deployment. Therefore, exposure biomarkers may be a valuable tool in assessing exposures and risk from environmental and occupational chemicals and hence imperative to include in a comprehensive DoD preventive medicine program.
Joshua
C. Murtie
Molecular and Cell Biology
Doctor
of Philosophy
2004
Major Advisor: Regina Armstrong, Ph.D , Department of Anatomy, Physiology & Genetics
Dissertation Title: The Influence of Platelet-Derived Growth Factor and Fibroblast Growth Factor 2 on Oligodendrocyte Development and Remyelination
ABSTRACT
Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) characterized by repeated episodes of autoimmune-mediated demyelination. Symptoms of the disease range from loss of vision to paralysis with each episode resulting in a decreased remyelination response. If remyelination does not occur, bare axons will not be able to function properly either by inefficient saltatory conduction or by degeneration resulting from a lack of myelin. This study examines the effects of growth factors on recovery from demyelination. Specifically, what roles do platelet-derived growth factor (PDGF) and fibroblast growth factor 2 (FGF2) play during remyelination of the central nervous system? This question will be addressed using the cuprizone model of demyelination with significant remyelination. The remyelination response in this model will be examined in FGF2 knockout mice as well as PDGF alpha receptor (PDGF R) heterozygous mice. This study examines the elimination of FGF2 signaling and the reduction of PDGF signaling in an animal model of demyelination with significant remyelination. The current results demonstrate that the predominant role for FGF2 during development and remyelination is that of an inhibitor of oligodendrocyte progenitor differentiation. PDGF was determined to maintain the normal non-lesioned density of oligodendrocyte progenitors as well as oligodendrocytes. Furthermore, PDGF was also identified as a mitogen for oligodendrocyte progenitors during remyelination. Together these data indicate that PDGF and FGF2 are critical regulators of adult remyelination in vivo.
Type 2 diabetes affects 16 million Americans and disproportionately affects ethnic minorities. Specifically, African American and Hispanics are twice as likely to have Type 2 diabetes compared to their Caucasian counterparts. The impact of this disparity goes beyond the greater prevalence of the disease and includes greater morbidity and mortality. The recent Institute of Medicine (IOM) report documents racial and ethnic disparities in the treatment for many different medical conditions, including diabetes. Understanding and combating health disparities among minority groups is a national priority. Many researchers have focused on socioeconomic status (SES) as the main cause in health disparities. Much of the research over the past two decades has examined the impact of health outcomes among the uninsured and much of this research has found that insured individuals have better health outcomes than those without insurance. In order to begin to unravel the myriad of factors that contribute to these health disparities, researchers must further examine whether there are differences among ethnic minorities and Caucasians with health insurance coverage. The current study examined the association of insurance status on health care utilization patterns and quality of self-care behaviors among ethnic minorities and Caucasians with Type 2 diabetes. The 1998 Medical Expenditure Panel Survey (MEPS), a nationally representative sample of the U.S. non-institutionalized civilians, dataset was used in this study. Data were extracted for insured Caucasian, African American, and Hispanic individuals aged 21-64 years with an ICD-9 diagnosis of Type 2 diabetes (i.e., with and without complications). Five hundred six individuals met the inclusion criteria. It was hypothesized that ethnic minorities would have fewer visits to a health care provider and lower expenditures for health care than Caucasians; indicating poorer utilization of care despite all individuals having health insurance coverage (i.e., private or public). There were three major findings of this study after controlling for potential confounds. First, despite having health insurance, low-income individuals with diabetes regardless of ethnicity, underutilized care as per recommended care in various clinical guidelines (i.e., less than 1 visit per year). Second, there were no differences observed in the frequency of prescriptions and prescription expenses for African Americans and Hispanics as compared to Caucasians. Lastly, total health services and out-of-pocket expenses for African Americans and Hispanics were lower than their Caucasian counterparts. The present findings highlight the importance of income level despite insurance on the amount and type of care received for low-income diabetics. There are racial differences in income such that Caucasians had higher mean incomes and therefore, had more money available to spend on medical expenses. One possible implication of these findings is that disparities in utilization and expenditures among racial and ethnic groups may be obscured at lower levels of income among patients with a chronic illness. Thus, ensuring that all individuals (i.e., particularly lower income diabetics) receive quality care, irrespective of income and ethnicity, should continue to be a goal of health care in the United States.
Nicole
Angela Vaughn
Department of Medical and Clinical Psychology
Doctor
of Philosophy
2004
Major Advisor: Tracy Sbrocco, Ph.D , Department of Medical and Clinical Psychology
Title
of Dissertation: Impact of Insurance Status on Health Care Utilization and
Quality of Self-Care Among Ethnic Minorities
with Type 2 Diabetes
ABSTRACT
Type 2 diabetes affects 16 million Americans and disproportionately affects ethnic minorities. Specifically, African American and Hispanics are twice as likely to have Type 2 diabetes compared to their Caucasian counterparts. The impact of this disparity goes beyond the greater prevalence of the disease and includes greater morbidity and mortality. The recent Institute of Medicine (IOM) report documents racial and ethnic disparities in the treatment for many different medical conditions, including diabetes. Understanding and combating health disparities among minority groups is a national priority. Many researchers have focused on socioeconomic status (SES) as the main cause in health disparities. Much of the research over the past two decades has examined the impact of health outcomes among the uninsured and much of this research has found that insured individuals have better health outcomes than those without insurance. In order to begin to unravel the myriad of factors that contribute to these health disparities, researchers must further examine whether there are differences among ethnic minorities and Caucasians with health insurance coverage. The current study examined the association of insurance status on health care utilization patterns and quality of self-care behaviors among ethnic minorities and Caucasians with Type 2 diabetes. The 1998 Medical Expenditure Panel Survey (MEPS), a nationally representative sample of the U.S. non-institutionalized civilians, dataset was used in this study. Data were extracted for insured Caucasian, African American, and Hispanic individuals aged 21-64 years with an ICD-9 diagnosis of Type 2 diabetes (i.e., with and without complications). Five hundred six individuals met the inclusion criteria. It was hypothesized that ethnic minorities would have fewer visits to a health care provider and lower expenditures for health care than Caucasians; indicating poorer utilization of care despite all individuals having health insurance coverage (i.e., private or public). There were three major findings of this study after controlling for potential confounds. First, despite having health insurance, low-income individuals with diabetes regardless of ethnicity, underutilized care as per recommended care in various clinical guidelines (i.e., less than 1 visit per year). Second, there were no differences observed in the frequency of prescriptions and prescription expenses for African Americans and Hispanics as compared to Caucasians. Lastly, total health services and out-of-pocket expenses for African Americans and Hispanics were lower than their Caucasian counterparts. The present findings highlight the importance of income level despite insurance on the amount and type of care received for low-income diabetics. There are racial differences in income such that Caucasians had higher mean incomes and therefore, had more money available to spend on medical expenses. One possible implication of these findings is that disparities in utilization and expenditures among racial and ethnic groups may be obscured at lower levels of income among patients with a chronic illness. Thus, ensuring that all individuals (i.e., particularly lower income diabetics) receive quality care, irrespective of income and ethnicity, should continue to be a goal of health care in the United States.