Medical Sciences Commons^™

Immunotoxicological Evaluation Of Critical Windows Of Development Following Exposure To 1,2:5,6 Dibenzanthracene In B6c3f1 Mice, Denise Marie Hernandez

Theses and Dissertations

Numerous findings have suggested that the increased prevalence of childhood illnesses such as cancer, infection, and allergy may be due to environmental exposures. One such cause may be maternal smoking or passive smoke exposure. Known immunotoxicants in cigarette smoke and environmental pollution include polycyclic aromatic hydrocarbons such as 1,2:5,6 Dibenzanthracene (DBA). The objective of these studies was to evaluate the immunosuppressive effects of DBA on various stages of immune system development. Adult mice were administered DBA daily in corn oil at dose levels of 158, 500, 1580, and 5000 µglkg S.C. for 28 days. Immunosuppression was not observed at levels …

Influence Of The Vitamin D3 Analog Eb 1089 On Senescence And Cell Death Pathways In The Response Of Breast Tumor Cells To Ionizing Radiation, Gerald Alan Demasters

Theses and Dissertations

A senescence-like growth arrest succeeded by rapid recovery of proliferative capacity is observed in MCF-7 breast tumor cells exposed to fractionated radiation (5 x 2Gy) alone. Exposure to the vitamin D3 analog EB 1089 (100nM) prior to irradiation converts the initial growth arrest response to cell death in part through the inhibition of radiation-induced senescence and promotion of both apoptotic and autophagic cell death. More importantly, EB 1089 was shown to profoundly reduce the rate of recovery following fractionated irradiation. The effect of EB 1089 on the temporal response to radiation is also observed in MCF-7 cells expressing caspase 3, …

Action Of Tyrosyl Dna Phosphodiesterase On 3'-Phosphoglycolate Terminated Dna Strand Breaks, Haritha Tatavarthi

Theses and Dissertations

Free radical-mediated DNA double strand breaks (DSBs) are induced either directly by ionizing radiation or by certain chemicals like bleomycin. These breaks are terminated by 3'-PG (PO4CH2COOˉ) or 3'-phosphate groups formed as a result of fragmentation of deoxyribose. To study the nature of repair of these 3'-blocked breaks, we constructed substrates mimicking free-radical induced DSBs. Human and yeast tyrosyl DNA-phosphodiesterase (Tdpl) efficiently processed substrates with 3'-PGs, in either the presence or absence of magnesium, to give a 3'-phosphate. Gel filtration chromatography and western blotting codmed that the putative enzyme in human extracts that efficiently processed PG was indeed tyrosyl DNA-phosphodiesterase. …

Pathological Upregulation Of A Calcium-Stimulated Phosphatase, Calcineurin, In Two Models Of Neuronal Injury, Jonathan Elledge Kurz

Theses and Dissertations

Excitotoxic calcium influx and activation of calcium-regulated systems is a common event in several types of neuronal injury. This mechanism has been the focus of intense research, with the hope that a more complete understanding of how neuronal injury affects calcium-regulated systems will provide effective treatment options. This study examines one such calcium-stimulated enzyme, calcineurin, in the context of two common neurological pathologies, status epilepticus and traumatic brain injury.Status epilepticus was induced by pilocarpine injection. NMDA-dependent increases in calcineurin activity were observed in cortical and hippocampal homogenates. Upon closer examination, the most profound increases in activity were found to be …

Characterization Of The Tcof1 Gene Using A Neuroblastoma Cell Line And A Mouse Model, Lin Li

Theses and Dissertations

Treacher Collins syndrome (TCS) is an autosomal dominant craniofacial development disorder and is caused by mutations in the TCOF1 gene. The TCOFl protein treacle is a nucleolar protein and may function in ribosome biogenesis.Previously, we identified downstream candidate genes using microarray analysis after manipulating Tcofl levels in a murine neuroblastoma (NB) cell line. The list of genes includes cell cycle genes as well as the transcription factors Cnbp and Tbx2, which are known to affect the cell cycle through the c-myc and p19-Mdm2-p53-p21 pathways respectively. To further characterize the cellular effects of Tcofl, stably transfected NB cell lines with overexpression …

The Role Of Gonadal Hormones On Opioid Receptor Protein Density In Arthritic Rats, Matthew Kren

Theses and Dissertations

The majority of research on the endogenous opioid system has focused on various pain assays and the efficacy of different opioid agonists. However, minimal attention has been focused on the effects of gonadal hormones and their impact on the opioid peptide system. The present study was designed to determine the effects of modulation of gonadal hormones on the opioid receptor protein levels in Complete Freund's Adjuvant (CFA)-treated arthritic and non-arthritic male and female Lewis rats. Midbrain and spinal cord tissues were collected for comparison of the μ, δ, and κ receptor protein levels in arthritic and non-arthritic animals. Male gonadectomy …

A Twin Study Of Antisocial Behavior And Depression: Methodology, Etiology, And Comorbidity, Kelly A. Tracy

Theses and Dissertations

The etiological connection between internalizing and externalizing disorders is poorly understood. This manuscript aims to investigate the roles of genes and then environment in the development of Major Depressive Disorder (MDD) and Antisocial Personality Disorder (ASPD) and the nature of their comorbidity in young adults. Data from a sample of 2,291 young adult male and female twins from the Young Adult Follow Up Study (YAFU) of the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) were used to estimate the proportion of variation in these traits that can be accounted for by additive genetic, shared environmental, and unique environmental factors. …

Post-Juvenile Brain Development Modulates Seizure Characteristics And Diazepam Efficacy In The Rat Pilocarpine-Se Model, William H. Holbert Ii

Theses and Dissertations

These studies were completed to examine how status epilpeticus seizure characteristics are modulated during post-juvenile brain development. This may determine if postnatal age in rats is a better identifier of stages of post-juvenile brain development. The first study fully detailed the acute discrete seizure phase of the rat pilocarpine-SE model. Results for this study showed that Racine behavioral severity score, spike frequency, and seizure severity during the acute discrete seizure phase change in relation to post-juvenile brain developmental stages. The second study fully detailed early and late patterns of status epilepticus. Results for this study displayed modulation of time in …

The Study Of The Effect Of Drugs Of Abuse On Protein Kinase A Activity In Mouse Brain And Spinal Cord, George D. Dalton

Theses and Dissertations

Morphine and Δ9-THC are drugs that produce analgesia and rewarding effects. However, chronic treatment with morphine and Δ9-THC produces problematic side-effects including tolerance and physical dependence. The cellular mechanisms underlying opioid and cannabinoid antinociceptive tolerance have been studied for years. Research has demonstrated that the expression of morphine and Δ9-THC antinociceptive tolerance may be mediated through intracellular signaling pathways, such as the adenylyl cyclase /Protein Kinase A (PKA) cascade. The present study investigated the role of PKA in the expression of morphine and Δ9-THC antinociceptive tolerance. Male Swiss Webster mice were treated chronically with morphine or Δ9-THC and the warm-water …

The Effects Of Footshock On The Reinforcing Efficacy Of Cocaine In Male Long-Evans Rats, Elizabeth S. Hendrick

Theses and Dissertations

Many links exist between cocaine abuse and stress. The literature and laboratory studies in rats suggest that this could be because stress increases the reinforcing efficacy of cocaine. Using male Long-Evans rats, experiments in this thesis tested effects of footshock on the reinforcing efficacy of cocaine using a progressive ratio schedule of reinforcement. They also examined effects of footshock on the reinforcing efficacy of a half-maximal dose of cocaine. Finally, they tested the effects of footshock on cocaine self-administration in rats initially resistant to acquisition of cocaine self-administration. Footshock did not increase reinforcing efficacy of cocaine on a PR schedule …

Calcium And Glycolysis Mediate Multiple Bursting Modes In Pancreatic Islets, Richard Bertram, Leslie S. Satin, Min Zhang, Paul Smolen, Arthur Sherman

Pharmacology and Toxicology Publications

Abstract

Pancreatic islets of Langerhans produce bursts of electrical activity when exposed to stimulatory glucose levels. These bursts often have a regular repeating pattern, with a period of 10–60 s. In some cases, however, the bursts are episodic, clustered into bursts of bursts, which we call compound bursting. Consistent with this are recordings of free Ca²⁺ concentration, oxygen consumption, mitochondrial membrane potential, and intraislet glucose levels that exhibit very slow oscillations, with faster oscillations superimposed. We describe a new mathematical model of the pancreatic β-cell that can account for these multimodal patterns. The model includes the feedback of …

The Ca2+ Dynamics Of Isolated Mouse Β-Cells And Islets: Implications For Mathematical Models, Min Zhang, Paula Goforth, Richard Bertram, Arthur Sherman, Leslie S. Satin

Pharmacology and Toxicology Publications

ABSTRACT

[Ca²⁺]_i and electrical activity were compared in isolated β-cells and islets using standard techniques. In islets, raising glucose caused a decrease in [Ca²⁺]_i followed by a plateau and then fast (2–3 min⁻¹), slow (0.2–0.8 min⁻¹), or a mixture of fast and slow [Ca²⁺]_i oscillations. In β-cells, glucose transiently decreased and then increased [Ca²⁺]_i, but no islet-like oscillations occurred. Simultaneous recordings of [Ca²⁺]_i and electrical activity suggested that differences in [Ca²⁺]_i signaling are due to …

Genetic Dissection Of Behavioral And Neurogenomic Responses To Acute Ethanol, Aaron Wolen

Theses and Dissertations

Individual differences in initial sensitivity to ethanol are strongly related to the heritable risk of alcoholism in humans. To elucidate key molecular networks that modulate ethanol sensitivity we performed a systems genetics analysis of ethanol-responsive gene expression in brain regions of the mesocorticolimbic reward circuit (prefrontal cortex, nucleus accumbens and ventral midbrain) across the BXD RI panel, a highly diverse family of isogenic mouse strains before and after treatment with ethanol. Acute ethanol altered the expression of ~2,750 genes in one or more regions and 400 transcripts were jointly modulated in all three. Ethanol-responsive gene networks were extracted with a …

Titrating And Evaluating Multiple Drug Regimens Within Subjects, Margaret Shih

Theses and Dissertations

The dosing of combination therapies is commonly undertaken empirically by practicing physicians, and there is a lack of a coherent algorithm to approach the problem of combination dosing. Current methods of evaluating multiple drug combinations in clinical trials generally do not provide information regarding the location of more effective dosages when the combination is not found to differ from the standard, even though the absence of a difference does not necessarily mean the new combination is ineffective. Additionally, if a new combination is found to be more effective, often a large proportion of the subjects has not benefited from the …

The Phantom Burster Model For Pancreatic Β-Cells, Richard Bertram, Joseph Previte, Arthur Sherman, Tracie A. Kinard, Leslie S. Satin

Pharmacology and Toxicology Publications

Abstract

Pancreatic β-cells exhibit bursting oscillations with a wide range of periods. Whereas periods in isolated cells are generally either a few seconds or a few minutes, in intact islets of Langerhans they are intermediate (10–60 s). We develop a mathematical model for β-cell electrical activity capable of generating this wide range of bursting oscillations. Unlike previous models, bursting is driven by the interaction of two slow processes, one with a relatively small time constant (1–5 s) and the other with a much larger time constant (1–2 min). Bursting on the intermediate time scale is generated without need …

Modulation Of The Bursting Properties Of Single Mouse Pancreatic Β-Cells By Artificial Conductances, T.A. Kinard, G. De Vries, A. Sherman, L. S. Satin

Pharmacology and Toxicology Publications

Abstract

Glucose triggers bursting activity in pancreatic islets, which mediates the Ca²⁺ uptake that triggers insulin secretion. Aside from the channel mechanism responsible for bursting, which remains unsettled, it is not clear whether bursting is an endogenous property of individual β-cells or requires an electrically coupled islet. While many workers report stochastic firing or quasibursting in single cells, a few reports describe single-cell bursts much longer (minutes) than those of islets (15–60 s). We studied the behavior of single cells systematically to help resolve this issue. Perforated patch recordings were made from single mouseβ-cells or hamster …

Inactivation Of Hit Cell Ca2+ Current By A Simulated Burst Of Ca2+ Action Potentials, L. S. Satin, S. J. Tavalin, P. D. Smolen

Pharmacology and Toxicology Publications

ABSTRACT A novel voltage-clamp protocol was developed to test whether slow inactivation of Ca2+ current occurs during bursting in insulin-secreting cells. Single insulin-secreting HIT cells were patch-clamped and their Ca2+ currents were isolated pharmacologically. A computed ,3-cell burst was used as a voltage-clamp command and the net Ca2+ current elicited was determined as a cadmium difference current. Ca2+ current rapidly activated during the computed plateau and spike depolarizations and then slowly decayed. Integration of this Ca2+ current yielded an estimate of total Ca influx. To further analyze Ca2+ current inactivation during a burst, repetitive test pulses to + 10 mV …

Comparison Of Virulent And Avirulent Legionella Pneumophila And Evaluation Of Fish As A Potential Environmental Reservoir/Experimental Model, Sandra Reading Sommer

Theses and Dissertations

Legionella pneumophila was first recognized as a cause of human pneumonia in 1976 . Since then, much has been learned about the microbiology, pathophysiology and epidemiology of this organism. The features which permit one strain but not another to invade human lung tissue and produce disease remain incompletely understood. This study e valuated several attributes of a virulent and an avirulent strain of L. pneumophila in an attempt to identify characteristics which would distinguish the two. Evaluation of a new medium, buffered egg yolk agar, showed that virulence was maintained after 26 passages, which was the same as the buffered …

Nosocomial Respiratory Tract Infections Associated With The Use Of Ventilatory Support Systems: Epidemiological And Bacteriological Study Of The Effect Of Changing Breathing Circuits At 24 Or 48 Hours, Virginia Archer Lamb

Theses and Dissertations

Nosocomial (hospital-acquired) pneumonia (HAP) continues to be an important cause of morbidity and mortality in the hospital. HAP is the third most common nosocomial infection after urinary tract and surgical wound infections. In addition, HAP is the nosocomial infection with the highest mortality rate. These infections are often difficult to treat, because most are caused by Gram-negative bacilli (GNB) that may be highly resistant to antimicrobial agents. HAPs frequently occur in intensive care patients with underlying lung and/or systemic diseases. Many patients are intubated and are on assisted ventilation. Several sources of infection associated with ventilators or respirators have been …

Clinical Findings In Four Children With Biotinidase Deficiency Detected Through A Statewide Neonatal Screening Program, Barry Wolf, Gregory S. Heard, Linda G. Jefferson, Virginia K. Proud, Walter E. Nance, Karen A. Weissbecker

Human and Molecular Genetics Publications

Four children with biotinidase deficiency were identified during the first year of a neonatal screening program for this disease in the Commonwealth of Virginia. Two unrelated probands were identified among the 81,243 newborn infants who were screened. In addition, two siblings of one of these infants were found to be affected. Both probands had mild neurologic symptoms at two and four months, respectively, and the two older children had more severe neurologic abnormalities, cutaneous findings, and developmental delay at two and three years of age. However, none of the affected children had acute metabolic decompensation. Previous studies have shown that …

Discordant Expression Of Fetal Hydantoin Syndrome In Heteropaternal Dizygotic Twins, Mary C. Phelan , B.S., John M. Pellock , M.D., Walter E. Nance , M.D., Ph.D.

Human and Molecular Genetics Publications

No abstract provided.

Systemic Membrane Defect In The Proximal Muscular Dystrophies, Nathan A. Pickard , Ph.D., Hanns-Dieter Gruemer , M.D., Harland L. Verrill , Ph.D., Edward R. Isaacs , M.D., Meinhard Robinow , M.D., Walter E. Nance , M.D., Ph.D., Edwin C. Myers , M.D., Barbara Goldsmith , B.S.

Human and Molecular Genetics Publications

Abstract

We studied lymphocyte capping in 61 patients with Duchenne, Becker, limb-girdle, facioscapulohumeral and congenital muscular dystrophies. All showed a markedly diminished percentage of capped cells when compared with 86 normal controls, providing support for previous evidence that an alteration in membrane fluidity may be a common pathogenic feature in several genetically distinct forms of proximal muscular dystrophy.

Heterozygous carriers of Duchenne muscular dystrophy showed diminished capping that was indistinguishable from that of afflicted males and was often present even when serum enzyme levels were normal. Studies in 25 families with 16 suspected sporadic cases indicated that no more than …