Assessment of oxygen saturation (O2Sat) in the optic nerve head (ONH) under controlled intraocular pressure (IOP) elevations may facilitate the detection of early phase glaucoma. Objective of this research is to quantify O2Sat in response to acute IOP elevations in the ONH of cynomolgus monkey Hyperspectral imaging (HSI) was used to test the hypothesis that O 2Sat distribution resulting from graded IOP elevations in retinal vessels and the ONH can be detected by HSI technique. Assessment of percent O 2Sat in retinal vessels and the ONH was carried out using least-squares curve fit of experimental spectral curves calibrated with reference curves. A previous algorithm for relative O2Sat calculation was improved by correction for blood volume which allowed comparison of O 2Sat in vessels and in the ONU, and tested on a multi-spectral imaging (MSI) system to reduce the time required to collect imagery from human subjects. Linear relationship was found between relative and calculated percent O 2Sat. The effects of IOP on the O2Sat were visualized in saturation maps. Retinal arteries showed nonsignificant reduction in O 2Sat between IOPs of 10 and 30 mm Hg (P = 0.805) and significant reductions at 45 and 55 mm Hg (P = 0.01, P < 0.0001 respectively); veins showed incremental reduction in O2Sat at each elevation of IOP. The responses in the rim of the ONH were similar to those in the artery, with the exception of the temporal cup, which only showed significant reduction in O2Sat at 55 min Hg. Models of oxygen diffusion out of the retinal artery, and of oxygen diffusion between paired arterioles and venules suggest that a further measurement of retinal arterial blood velocity is necessary Results are consistent with early studies that optic nerve fiber layer and prelaminar neural tissues may become ischemic at low level of perfusion pressure. Findings of O2Sat at graded IOP elevations in experimental glaucoma and direct measurements of blood flow will be necessary to further assess the importance of these findings. The HSI and MSI techniques are useful in diagnosing conditions, monitoring treatments, and studying the mechanisms of the diseases / acase@tulane.edu

The goal of this work is to study how the physical properties of a thin coating of insulation, such as thermal conductivity and thickness, determine its overall effect on an object. Particular attention will be paid to the case where the coating exhibits anisotropic, or direction-dependent, thermal conductivity. Two general questions will be considered: how the properties of the coating determine the thermal protection of the insulated body, and which boundary conditions appear in a limiting boundary value problem on the interior body. The first question will be addressed via explicit estimates that compare the true temperature of the body to the temperature after assuming perfect insulation. This will be accomplished by analyzing the weak formulation of the heat equation and applying the method of eigenexpansion. The second question will be addressed by introducing auxiliary harmonic functions into the weak formulation of the boundary value problem. In this question we will restrict ourselves to objects in the plane and coatings that are optimally aligned / acase@tulane.edu

The neurons of the dentate gyrus play a critical role in the hippocampal tri-synaptic pathway. Granule cells located in this cellular layer are responsible for integrating large amounts of information emitted from the entorhinal cortex before propagating signals via the mossy fiber pathway to the CA3 subfield of the hippocampus. This circuitry has been shown to be critical to the formation of episodic and declarative memories. This type of memory is impaired in schizophrenics. Animal models based on the popular glutamate hypothesis have used NMDA antagonist such as PCP and ketamine to mimic the symptoms of schizophrenia to good effect. One such animal model utilizes sub-chronic administration of PCP to non-human primates. Numerous studies have shown that this treatment paradigm reliable produces deficits in prefrontal cortex functioning that mimics the dysfunctions associated with the schizophrenic phenotype. The present study used late adolescent vervet monkeys treated in the sub-chronic paradigm and sought to determine if structural changes occurred in the dentate gyrus. We report that no structural alterations to dentate granular cell morphology were linked to sub-chronic PCP administration. This result may be due to the fact that the late adolescent subjects used had yet to develop fully mature glutatmatergic circuitry and were thus not susceptible to the changes in brain chemistry commonly associated with NMDA antagonist administration / acase@tulane.edu

Natural disasters such as Hurricane Katrina can cause a range of psychological problems in youth, including posttraumatic stress (PTS) symptoms (Norris et al., 2002). Not everyone who experiences a disaster develops PTS symptoms. Individual characteristics such as gender (Tolin & Foa, 2008) and coping style (LaGreca et al., 1996) can influence the development of PTS symptoms post-disaster. Substance use (SU) is one type of coping strategy that increases among adolescents after exposure to disasters (Chemtob et al., 2009; Reijneveld et al., 2003). While adult studies have found that drug use as a form of coping has the potential to increase the risk of developing PTS as well as prolong and exacerbate symptoms (Stewart et al., 1998), few studies have examined this relationship in adolescents. Furthermore, preliminary evidence suggests that SU may uniquely influence the three PTS symptom clusters (Overstreet et al., 2010). The goal of this study will be to explore the effect of SU on PTS symptoms in general, and the individual symptom clusters. Participants included 687 predominately White females, ages 13-18 attending a private, Catholic school. Hurricane exposure was assessed via a 9-item questionnaire addressing loss and disruption caused by the hurricane. PTS was assessed using the17-item subscale of the Los Angeles Symptoms Checklist (LASC; King et al., 1997). SU was measured using two LASC items that assessed problem SU. Hierarchical regression analysis was used to test the moderating role of SU on the relationship between disaster exposure and symptoms of PTS. Results indicate that in general, while SU is independently associated with PTS symptoms, it does not influence the relationship between exposure and overall PTS symptoms. However, for highly exposed youth, it does potentiate the relationship between exposure and avoidance/numbing symptoms of PTS / acase@tulane.edu

acase@tulane.edu

Lignin and pigment biomarkers were analyzed in sediments of the Louisiana Continental margin along two major depositional pathways (along shore and offshore to the Mississippi Canyon) from SW Pass in July 2003. Results from surface sediments indicate resuspension and reworking of shelf sediments in shallow waters and mobile mud deposits were more effective at oxidizing terrestrial material west of SW Pass than to the southwest. Barataria Bay material may be a contributing source of sedimentary organic matter in shallow shelf areas bordering the Bay and is thus potentially important in carbon cycling. Hurricane Ivan mobilized sedimentary organic carbon (SOC) offshore and homogenized terrestrial sediment parameters and gradients Results from box-core profiles showed preferential loss of more labile pigment SOC during burial and diagenesis. Low burial efficiencies along the western transect for bulk and labile biomarkers indicate mobile muds were efficient in the remineralization of labile organic matter. Lignin appeared to be a useful paleo indicator in dynamic RioMar environments likely reflecting source input rather than diagenesis after initial deposition. Pigment concentrations and ratios may not be useful in a quantitative sense for paleo-reconstructions within dynamic RioMar regions. Oxic degradation of labile material in the Surface Active Zone was highly efficient, effecting the quantity and quality of material buried below Lignin profiles in age-dated cores (210Pb geochronology) indicate artificial reservoir retention as a major control on organic carbon quantity and quality post-1950 reaching the margin, whereas, pre-1950 sediments may reflect soil erosion due to land-clearing and farming practices. Terrestrially derived organic carbon signatures were mixed angiosperms over the last 150 yrs. Stochastic events such as hurricanes and large river floods have a measurable, albeit ephemeral, effect on the shelf SOC record. Land-use changes in the MR basin have likely affected carbon cycling and SOC burial on the LCM over a large spatial extent as observed by similar trends in cores from across and along margin. Finally, sediment focusing seems to be a very important aspect that can complicate down-core interpretation when trying to make comparisons over wide spatial scale / acase@tulane.edu

Parent-child conversations in science museums may support children's interest and understanding of science. Researchers have been investigating programs to optimize parental guidance and deepen families' scientific exploration in museums. Inquiry is an approach to science teaching science that mirrors the scientific method, allowing participants to raise questions about a scientific phenomenon and conduct investigations to answer those questions. In this study, an experimental design was used to test the impact of participation in an inquiry-based activity on families' conversations at six science museum exhibits. Half of the families participated in an inquiry activity before exploring exhibits, and half of the families participated in an inquiry activity after exploring exhibits. Two sets of variables found to be important contributors to parent-child conversation at science museums (i.e., exhibit qualities and individual characteristics) were considered. Results indicated that participation in a guided inquiry activity significantly increased parents' high-quality learning talk, specifically providing explanations and making connections to prior experience. Exhibit qualities and individual characteristics are important considerations for designing and implementing an inquiry intervention. Families talked about the inquiry activity after the visit and applied what they had learned to real-life situations at home. Inquiry activities have the potential to empower parents with tools to help them scaffold children's emerging scientific knowledge during shared activity in a science museum. Implications and future directions are discussed. / acase@tulane.edu

We use compound genetic mutants to analyze two transcription factors with demonstrated functions in hair shaft differentiation, Msx2 and Foxn1. First, we show that maintenance of Notch1 expression in the hair follicle matrix requires both factors, indicating a redundant activity of these proteins. In their absence, matrix cell proliferation is compromised; medulla and inner root sheath (IRS) differentiation is affected as evidenced by reduced K17 and Gata3 expression, respectively. We also identify a 4.7 kb of Notch1 promoter sequence which specifically drives EYFP expression in hair follicles and is regulated by Foxn1. Moreover, Foxn1 directly binds to this promoter as evidenced by ChIP assay. Whereas these aspects of the phenotype can be attributed to loss of Notch1, Msx2/Foxn1 also contribute independently of Notch1 to cortex and cuticle differentiation - several cortical and cuticle keratins are no longer expressed in the double mutant follicles. Despite the presence of a normal number of hair follicles and lineage-restricted stem cells, the impact of these defects is the complete loss of all visible external hairs. Since we find that BMP4 can regulate Foxn1 expression independent of Msx2, we suggest that these two genes function in parallel pathways downstream of BMP signaling and upstream of Notch1. Our results reveal a global requirement for Msx2 and Foxn1 in the hair matrix where they maintain Notch1 expression and thus indirectly control IRS and medulla differentiation, while directly supporting many aspects of cortical differentiation. Except for the genetic interplays between Msx2 and Foxn1 in the hair follicles, both Msx2 and Foxn1 are required for proper differentiation of the keratogenous zone, proliferation of the distal matrix and organization of the nail bed in the nail unit. Loss of both Msx2 and Foxn1 results in reduced hair specific keratin expression in the keratogenous zone, hyperproliferation of the distal matrix and stratification of the nail bed / acase@tulane.edu

Non-lethal amputation injuries following a typical wound healing response, in human beings may result in lifelong disability. Therefore, the ability to induce regeneration of amputated limbs, similar to axolotls, is of primary interest of regenerative medicine. The only regions in mammals that demonstrate epimorphic regeneration is restricted to the terminal phalanx. Amputation of the distal elements of the terminal phalanx of mice causes an initial wound healing response followed by a complete regeneration of the nail, bone and connective tissue. Thus far, most functional and genetic studies of digit regeneration have been performed in embryos or neonates, however, few studies have examined digit regeneration in the adult mouse Here, the first chapter encompasses a comprehensive, morphological, histological and volumetric analysis of the stages of adult digit regeneration. We found that amputation of approximately one third of the length of the digit led to an initial wound closure and an accumulation of a zone of mesenchymal cells that resembled a blastema at 10-12 days post-amputation. Next we performed a region-specific immunohistochemical analysis of the regenerating connective tissue using antibodies specific for Vimentin, a common mesenchymal marker, SCA-1, a putative stem-cell marker, and CD-31, an endothelial marker. This analysis revealed the ubiquitous expression of Vimentin in the blastema. However, only 7% of cells expressed SCA-1, and only 10% of cells expressed CD-31. Interestingly, 94% of SCA-1+ cells in the blastema were also CD-31 +. Compared to digits that were newly amputated, the total SCA-1 +, CD-31+, and SCA-1+/CD-31 + cells in the bone marrow and connective tissue were significantly lower when compared to the regenerate. According to our knowledge, this is the first molecular phenotypic expression analysis of the regenerating blastema tissue during adult digit regeneration The cellular origins of the adult mouse blastema are unknown. A lack of a means to analyze the origins of blastema cells has slowed our progress understanding the fundamentals of digit tip regeneration. In order to analyze the cellular origin of the blastema, the second chapter encompasses on developing methods that involve in vivo injection/electroporation of plasmids, and in vivo DiI injection and subsequent in vivo imaging of adult mouse digit tips. Using these methods, we demonstrate the movement of existing vimentin-positive local dermal connective tissue cells that contribute to the blastema during regeneration of the terminal phalanx In most adult mammalian amputated appendages, the wound healing responses lead to scaring and regeneration failure. However, the wound healing events of the amputated distal portions of the adult mouse digit tip leads to regeneration. This provides a rare opportunity to study the wound healing mechanisms present at an injury conducive for adult mammalian appendage regeneration. However, the genetic mechanisms related to adult mouse digit tip wound healing are yet to be explored. In order to generate a database of genes related to early wound healing, we conducted microarray analysis that revealed up regulation of 181 genes and down regulation of 286 genes during an early wound healing phase of regeneration. We used semi quantitative RTPCR, and immunohistochemistry and verified the upregulation of genes that include Mmp9, CathepsinK, and Tgfbeta1 three genes identified by the microarray. Due to functional significance of Tgfbeta signaling in other regeneration competent vertebrates systems, we decided to further analyze the expression pattern of a downstream target of Tgfbeta signaling, PSmad2, and found a similar expression pattern to that of Tgfbetar1. Injection of a Tgfbetar1 inhibitor, SB431542, during the wound healing phase inhibited blastema formation, thus suggesting the possibility that early wound healing events that lead to regeneration competence of the digit tip may proceed via Tgfbeta signaling / acase@tulane.edu

The mechanochemical synthesis of functionalized silicon nanoparticles using High Energy Ball Milling (HEBM) is described. This method facilitates the fragmentation of mono crystalline silicon into the nanometer regime and the simultaneous surface functionalization of the formed particles. The surface functionalization is induced by the reaction of an organic liquid, such as alkynes and alkenes with reactive silicon sites. This method can be applied to form water soluble silicon nanoparticles by lipid mediated micelle formation and the milling in organic liquids containing molecules with bi-functional groups, such as allyl alcohol Furthermore, nanometer sized, chloroalkyl functionalized particles can be synthesized by milling the silicon precursor in the presence of an o-chloroalkyne with either alkenes or alkynes as coreactants. This process allows tuning of the concentration of the exposed, alkyl linked chloro groups, simply by varying the relative amounts of the coreactant. The silicon nanoparticles that are formed serve as the starting point for a wide variety of chemical reactions, which may be used to alter the surface properties of the functionalized nanoparticles Finally, the use of functionalized silicon particles for the production of superhydrophobic films is described. Here HEBM proves to be an efficient method to produce functionalized silicon particles, which can be deposited to form a stable coating exhibiting superhydrophobic properties. The hydrophobicity of the silicon film can be tuned by the milling time and thus the resulting surface roughness of the films / acase@tulane.edu