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No description available.

No description available.

No description available.

Heat-labile enterotoxin of enterotoxigenic Escherichia coli and cholera toxin of Vibrio cholerae are structurally, functionally, and immunologically homologous proteins. In addition to their role as the main virulence factors responsible for diarrheal diseases, they also function as mucosal adjuvants for co-administered antigens. Numerous attempts have been made to dissociate the toxicity of these two molecules from their adjuvant properties. Unfortunately, different observations reported by various groups using a variety of animal models with different antigens, different mutants of LT or CT, and different routes of immunization have complicated rather than clarified that understanding. The objective of this thesis was to investigate the structure-activity relationship of LT using various classes of LT mutants in order to better understand the underlying mechanisms of LT-mediated adjuvanticity with respect to toxicity and other biological functions. Mutations at each of the three functional domains of LT, namely, the active site, the protease site, and the ER retention signal sequences, were constructed and characterized. Each LT mutant was examined for cytotoxicity in the Y-1 Adrenal Tumor Cell assay, enterotoxicity in the Patent Mouse model, the ability to induce cAMP accumulation in a non-polarized cell system, and the ability to function as an adjuvant when administered either intranasally or orally as assessed by induction of antigen-specific humoral and cell-mediated immune responses It is obvious that LT and CT have significant potential to facilitate the development of entirely new classes of vaccines for mucosal delivery. The results presented in this thesis make it clear that different mutants of LT have different properties, which vary depending upon the nature of the mutation and the route of delivery. Specifically, those mutants that retain the ability to induce cAMP elicit quantitatively and qualitatively different responses than do those mutants that lack this enzymatic function. The link between induction of cAMP and enterotoxicity must also be addressed. With the adjuvant effective dose of native LT and any of the mutants of LT in humans as yet unknown, it may be possible to establish a reasonable therapeutic window for use, in humans, of LT mutants that retain some level of residual enterotoxicity / acase@tulane.edu

Human immunodeficiency virus (HIV) infection causes a decrease in CD4 cell number and an increase in CD8 cell count. These cell numbers are used to assess disease progression in HIV-infected patients. In children, frequent invasive blood draws are undesirable. We therefore developed the technique of quantitative competitive reverse transcriptase polymerase chain reaction (QC-RT-PCR) to quantitate CD4 and CD8 mRNA levels from heelsticks or fingerpricks. This technique is extremely sensitive and can be applied to frozen samples. We found no correlation between CD4 and CD8 cell counts and mRNA levels of CD4 and CD8 as determined by QC-RT-PCR CD8+ cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells are the major cytotoxic components of the antiviral immune response. The major pathway used by these cells in the antiviral response includes perforin and granzymes. We assessed the mRNA levels of granzyme B in peripheral blood mononuclear cells of IRV-infected versus noninfected individuals by QC-RT-PCR. There were significantly fewer HIV patients with detectable granzyme B levels than controls. This implies that cytotoxicity may be impaired due a deficient quantity of cytotoxic granules The in utero HIV transmission rate should theoretically be much higher than currently estimated. Protective mechanisms may exist to prevent in utero transmission. Immunoglobulin G (IgG) crosses the placenta, and neutralizing antiviral antibody may prevent in utero transmission. To study this hypothesis, the quantity and quality of the antiviral IgG in amniotic fluid of infected mother-infant pairs was assessed. Using p24 antigen capture ELISA, detectable levels of HIV p24 antigen were found in the amniotic fluid of infected mothers. By western blot, significantly high levels of antiviral IgG were found in amniotic fluid samples versus plasma. Infectivity reduction assays were performed, and extremely dilute human and macaque amniotic fluids were able to neutralize their respective viruses' infectivity, except for the samples from an SIV-positive mother whose infant was infected in utero. These results show that HIV-1 and SIV neutralizing antibodies may play a crucial role in protecting the fetus from in utero infection / acase@tulane.edu

Concussions are a common type of traumatic brain injury resulting in a series of physical, emotional, and psychosocial symptoms. Following a concussion, emotional processing is thought to be altered through small functional and structural disruptions that impact information processing pathways, which may eventually manifest as behavioral impairments. Thus, the use of both behavioral and functional outcomes may be effective for assessing the changes in emotional processing that may occur following a concussion. The primary purpose of this study was to examine behavioral and neurocognitive differences in response to emotional face images between individuals with and without a history of concussion. Fifty participants (18 female; 32 male) were recruited and assigned to either the concussed (n = 23; Mage = 24.1 ± 1.0) or non-concussed (n = 27; Mage = 23.2 ± 0.6) group based on medical and self-reported concussion history. Participants completed a modified emotional oddball paradigm where representative positive (smiling), negative (frowning), and neutral faces from the Radboud Faces Database were displayed. Neuroelectric measures of P3 amplitude and latency, as well as behavioral measures of response accuracy and reaction time were assessed during the experiment. The concussion group showed significant reductions in accuracy, but no difference in reaction time compared to the non-concussed group. An increase (i.e., slower) in P3 latency was also found in the concussed group, with no observed group differences in P3 amplitude. Findings suggest that concussions may lead to chronic neuroelectric and behavioral deficits in classifying emotional, facial expressions.

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No description available.

Master of Science / Department of Human Nutrition / Denis M. Medeiros / Copper deficiency has been linked with many health problems, among them cardiac hypertrophy. Because of its potential for causing oxidative damage, copper within the cell must be bound to chaperone proteins. In this thesis, we examined the role of dietary copper deficiency in the regulation of select copper chaperone proteins in cardiac tissue of rats. Sixteen weanling male Long-Evans rats were randomized into treatment groups, one group receiving a copper deficient diet (< 1 mg Cu/kg diet) and one group receiving a diet containing adequate copper (6 mg Cu/kg diet) for 5 weeks. Rats were sacrificed and a small blood sample was removed to determine hematocrit. Also, heart and liver tissues were removed for subsequent analysis. Rats fed the copper deficient diet had lower body weights but greater heart weights and heart:body weight. Hematocrit levels and liver copper concentrations were markedly decreased in copper deficient rats. These variables indicated that the copper deficient diet did in fact induce a copper deficiency in these animals. Non-myofibrillar proteins from the hearts were removed and separated by SDS-PAGE. Western Blotting was used to determine the concentrations of CTR1, CCS, Cox17, SCO1, Cox1 and Cox4. No changes were observed in the concentrations of CTR1 and Cox17. CCS and SCO1 were up-regulated as a result of copper deficiency, while Cox1 and Cox4 were both down-regulated. However, use of another antibody against Cox subunits suggested that only the nuclear encoded subunits including subunit IV were decreased, but not subunits I and II. These data provide new insight into the cardiac hypertrophy observed in copper deficiency, which suggests that select chaperone proteins may be up-regulated by a dietary copper deficiency.