Browsing by Subject "Mouse"
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Item High resolution retinal imaging to evaluate laser and light safety in the retina for near and long term health effects(2012-12) Pocock, Ginger Madeleine; Snodderly, D. Max; Rylander, H. Grady (Henry Grady), 1948-; Markey, Mia K.; Milner, Tom E.; Oliver, Jeffrey W.The purpose of this research was to investigate detect and monitor laser-tissue interactions at threshold and potentially sub-threshold levels of injury. High resolution imaging modalities can provide a deeper understanding of candidate biomarkers disease and injury at the molecular, cellular, and tissue-levels which can be used to identify and diagnose early stages disease and damage. In addition, multi-scale and multi-modal imaging have also been used to identify inherent biomarkers of retinal disease and injury. Monitoring tissue changes can be mapped back to biological changes at the cellular and sub-cellular level. Diseases often alter tissue on the ultra-structural level yet retinal clinical diagnosis often monitor changes in tissue at the organ level. If injury and disease is detected and diagnosed during an “early” stage of development, treatments and drug interventions may prevent further spread of the pathology. Non-invasive imaging is expected to be a valuable tool for in vivo medical research as well as for the diagnosis and management of disease. In addition to developing new imaging tools and techniques to image the retina, the identification of inherent biomarkers of disease and health using diagnostic methods are almost equally as important. Using the inherent optical properties of retinal tissue, we can non- invasively quantify differences in the absorption and reflection of light to gauge the risk for visual disability or worse yet irreversible vision loss as a result of retinal disease and chronic light exposure. The research presented with in this dissertation is three separate studies aimed at identifying light injury and potential biomarkers indicating the risk of light mediated development of disease.Item Immunosuppressive dietary n-3 polyunsaturated fatty acids differentially modulate costimulatory regulation of murine CD4+ T-cell function(Texas A&M University, 2005-02-17) Ly, Lan H.Consumption of fish oils (FO) enriched with the n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is beneficial to a variety of inflammatory disorders due, in part, to the alteration of membrane composition of T-lymphocytes and other immune cells. We previously observed that down-regulation of proliferation and cytokine synthesis by CD4+ T-cells in mice fed diets rich in n-3 PUFA was dependent on the involvement of CD28, a co-stimulatory molecule necessary for T-cell activation. Since the co-receptor homologues, CD28 and CTLA-4, have opposing effects on T-cell activation, we hypothesized that the balance of costimulatory and downregulatory properties of CD28 and CTLA-4, respectively, would be altered by diet. A significant increase (p<0.05) in CD28 and CTLA-4 surface expression was observed in CD4+ T-cells post-stimulation with phorbol ester and calcium ionophore (PMA/Iono) or anti-CD3 and anti-CD28 (αCD3/CD28) antibodies in all diet groups. A significant increase (p<0.01; 20%) in the number of CD28 molecules was observed in n-3 PUFA vs. CO-fed mice after 48 h of in vitro CD4+ T-cell activation, and both CTLA-4 mRNA transcript and protein levels were upregulated by 50% at 72 h post-activation (p<0.01). Treatment with anti-CTLA-4 mAb in vivo in Mycobacterium bovis (BCG)-vaccinated mice did not alter the suppressive effects of dietary n-3 PUFA on antigen (PPD)-induced lymphocyte proliferation or delayed hypersensitivity reactions. T-cells from both the C57BL/6 and IL-10mice fed dietary n-3 PUFA after 72 h of in vitro stimulation with αCD3/CD28. CD4T-cells from C57BL/6 mice fed DHA produced significantly less IFNγ and IL-10, while CD4T-cells from IL-10Ligation of CD28 upregulates IL-10 receptor (IL-10R) expression on CD4+ T-cells. Therefore, we hypothesized that dietary n-3 PUFA would suppress T-cell function through the effects of IL-10. Surprisingly, the proliferation of purified splenic CD4+ T-cells activated in vitro with αCD3/CD28 was suppressed by dietary n-3 PUFA in both conventional mice (C57BL/6) and IL-10 gene knockout (IL-10(-/-)) mice. Furthermore, IL-10R cell surface expression was significantly down-regulated on CD4+ T-cells from both the C67BL/6 and IL-10(-/-) mice fed dietary n-3 PUFA produced significantly more IFNγ compared to the CO-fed group.Item Neurotropism of Theiler's murine encephalomyelitis virus(Texas A&M University, 2005-11-01) Villarreal, DorissaTheiler??s murine encephalomyelitis virus (TMEV) can infect the central nervous system (CNS) and cause neurological damage. The exact route by which TMEV enters the CNS remains unknown. Two hypotheses suggest that TMEV enters the CNS either by the neural and/or the hematogenous pathway. To explore these hypotheses, the GDVII strain of Theiler??s virus was inoculated via different routes in susceptible mice. The incidence of paralysis and/or encephalitis was evaluated. The forms of paralysis displayed corresponded to the site of viral inoculation. Following intramuscular (i.m.), intraperitoneal (i.p.), intravenous (i.v.) and footpad routes of injection, bilateral and or contralateral paralyses were observed. In mice injected intratongue, tongue paralysis was observed. Intracranial (i.c.) injections resulted in 100% mortality. A detailed time course experiment was also completed which focused on the neural transport pathway used by TMEV to invade the CNS. The GDVII strain of Theiler??s virus was injected into the left gastrocnemius muscle and the hypoglossal nerve (CN XII). The incidence of paralysis and/or encephalitis was evaluated on the basis of clinical signs, immunofluorescent analysis, and histopathology. Following the i.m., route of injection, unilateral hind limb paralysis was observed in the injected limb and a weakening of the contralateral limb was also observed. In mice injected in the hypoglossal nerve, tongue paralysis was observed. Also, the penis of most affected males was prolapsed. The localization of viral antigen using fluorescent labeling correlated with the clinical signs of paralysis for both injections. The studies reported here support the theory that GDVII Theiler??s virus may gain access to the CNS through a neural transport pathway.Item Odor masking of a vertebrate carcass by a burying beetle (Nicrophorus marginatus)(Texas Tech University, 2006-05) Woodard, Charmaine; Deslippe, Richard J.; Zak, John; McIntyre, Nancy E.Burying beetles of the genus Nicrophorus (Coleoptera: Silphidae) use small vertebrate carcasses as food in raising their young with bi-parental care. These carcasses are stripped of hair and treated with oral and anal secretions by both males and females. Here, I report on whether Nicrophorus marginatus, a widely distributed species in North America, masks the odor of decomposing carcasses, and if so, how it accomplishes the masking. First, I compare the volatiles emitted by mouse carcasses from six different treatments, including mouse carcasses that are processed by male and female pairs of N. marginatus. The release of volatiles is assessed both by human subjects and by chemical analyses, employing solid phase extraction. Second, I examine the chemical composition of the anal secretions of both N. marginatus and N. carolinus by solid phase microextraction to gain insight into which compounds, if any, are involved in odor masking. The solid phase extraction and solid phase microextraction analyses were subsequently characterized by gas chromatography and mass spectrometry. The results of the solid phase microextraction analyses showed the commonalities and differences of several compounds between the two sexes and genders of burying beetles, but shed no light on whether any of them aids in odor masking. The solid phase extraction analyses showed an increase in an anal secretion of N. marginatus, methoxy-phenyl-oxime, with the increase in decomposing mouse carcass volatiles, suggesting that odor masking is taking place.Item Songs of aggression : the singing mouse model(2015-05) George, Andreas Sherron; Phelps, Steven Michael, 1970-; Crews, DavidSocial behavior is a vital part across vast taxa, from honey bees to elephants. This behavior is known to be modulated by nonapeptides acting on various nodes of the social behavior network (Newmann, 1999). Vasopressin and its evolutionary precursor vasotocin are both highly involved in the social brain. (De Vries and Panzica 2006; Goodson, 2005) Furthermore, it has been demonstrated that these systems are under the control of gonadal hormones (Bester-Meredith and Marler 2005). Here, we study the effects of hormones and experience on the social behaviors, specifically aggression, in the singing mouse Scotinomys teguina. These mice are known for their male stereotyped song used in territorial aggression as well as mate attraction. We gonadectomized the animals and coupled this with androgens at varying levels, or empty implants, to determine how gonadal hormones affect aggression and song. We discovered a significant increase in frequency of submission in animals following no hormone treatment, and a positive correlation with androgen level and physical aggression, as well as increase in propensity to sing. In a separate study, we also studied the singing response to social stimuli. We introduce the subjects to conspecific song, female bedding, and pink noise. We then recorded their responses following winning or losing encounters. We found animals increased their singing behavior in response to all stimuli following wins. Winning is known to increase aggression by allowing a transient increase in gonadal hormones. This study further bolsters the winner’s effect. Taken together, these experiments demonstrate in dynamic social behavior in a novel species that is modulated by hormonal states as well as social encounters.