Estrogen replacement prior to brain injury has been reported to be neuroprotective. Previous studies have shown that estrogen reduces inflammation after injury in the young adult forebrain, whereas ...in a reproductive senescence model, inflammation is exacerbated by estrogen. Reproductive senescent females are older acyclic and physiologically resemble the human menopause. Since this is the group that is likely to seek estrogen replacement, understanding the effects of estrogen on neural inflammation is important. The present studies monitor how reproductive age modulates the neural inflammatory response and examines the cellular locus of estrogen's dichotomous actions. The data indicate that microglia from young adult and aged hosts do not suppress LPS-induced IL-1β expression when pretreated with 17β-estradiol. However, circulating immune cells from estrogen pretreated young adult females had a significant suppression of LPS-stimulated cytokine expression, whereas in senescent animals, expression was increased. This was similar to the pattern of estrogen action seen in the brain injury model and suggested that circulating immune cells rather than microglia are altered by reproductive aging. Since the brain typically excludes circulating immune cells via the blood brain barrier, it is possible that neural inflammation resulting from as systemic inflammatory event would differ from that caused by local injury. To test the role of the aging blood brain barrier, young and senescent animals were injection systemically with LPS, and central and peripheral cytokine expression was measured. In young adults, estrogen suppressed IL-1β expression the olfactory bulb (protected by the blood brain barrier) but not in the pituitary gland (only partially protected by the blood brain barrier). In senescent females, estrogen replacement completely suppressed IL-1β in the pituitary and olfactory bulb, as well as lowered plasma corticosteroids, indicating that hormone treatment delayed the initiation of the immune response. Collectively, these data confirm that the inflammatory response is altered by reproductive age and extend these analyses to show that estrogen's age dependent effects on neural inflammation may actually be due to age-related changes in circulating immune cells and/or the blood brain barrier. These studies support the idea that compensatory changes incurred during reproductive aging may be incompatible with estrogen replacement.
Escherichia coli L-threonine dehydrogenase is a member of the Zn(2+)-containing alcohol/polyol dehydrogenase family. Methylation of His-90 of L-threonine dehydrogenase was recently found to cause ...total inactivation (J. P. Marcus and E. E. Dekker, 1995 Arch. Biochem. Biophys. 316, 413-420). Since His-90 is not conserved among the related dehydrogenases, this residue was changed to arginine, asparagine, and alanine by site-directed mutagenesis in order to probe its role. All three purified, homogeneous mutants, like wild-type enzyme, contained one Zn2+ atom/subunit and exhibited a sequential catalytic mechanism; the kcat value for each, however, was reduced approximately 10-fold. The K(m) value for threonine was elevated from 3 mM for wild-type enzyme to 31, 328, and 417 mM, respectively, for mutants H90R, H90N, and H90A. The activation energy of catalysis for mutant H90A was increased by 6.6 kcal/mol, suggesting that in the wild-type enzyme His-90 forms at least one crucial hydrogen bond in the transition state. Whereas wild-type enzyme catalyzed the oxidation of threonine amide (0.75 M) about twice as fast as this same concentration of threonine or 0.375 M L-2-amino-3-hydroxypentanoate, the reaction rate of mutant H90A with 0.75 M threonine amide or threonine methyl ester was 33- to 35-fold higher than with this level of threonine. Similarly, mutant H90N used 0.75 M threonine methyl ester or threonine amide as substrate 9- to 13-fold better than it used this concentration of threonine. Mutants H90A and H90N were more reactive with 0.225 M L-threonine hydroxamate than with 0.75 M threonine, but mutant H90A did not oxidize L-2-amino-3-hydroxypentanoate (0.375 M) and mutant H90N used this substrate poorly. The best substrates for mutant H90R were threonine methyl ester, threonine, and threonine amide (all tested at 0.75 M); 0.375 M L-2-amino-3-hydroxypentanoate was a poor substrate. The isolation and characterization of these first His-90 mutants of E. coli L-threonine dehydrogenase confirm the importance of this residue in catalysis and suggest that His-90 is an active-site residue which modulates the substrate specificity of L-threonine dehydrogenase.
Construction of land use and land cover (LULC) maps was accomplished through the use of remote sensing and GIS. Remote sensing and GIS were used to classify 1990 Landsat 5 and 2000 Landsat 7 ...Mississippi Gulf Coast imagery into six LULC classes: urban, barren, forested vegetation, non-forested vegetation, marsh, and water. An accuracy assessment was performed on the 2000 LULC map to determine the reliability of the map. Finally, GIS software was used to quantify and illustrate the various LULC conversions that took place over the ten year span of time. The paper concludes that remote sensing and GIS can be used to create LULC maps. It also notes that the maps generated can be used to delineate the changes that take place over time.
The South China Sea is a sea with strategically important shipping lanes, an abundance of maritime resources, and potentially large amounts of oil and gas deposits. Because of the significance of the ...sea, China has claimed almost all of it, which has caused the Association of Southeast Asian Nation members (ASEAN) whose countries surround the sea (Vietnam, Singapore, Indonesia, Malaysia, Brunei, and the Philippines) to take a stance against the encroachment. The most important non-Chinese claimant in the dispute is the Philippines, which shares a mutual defense treaty with the United States. The dispute has been analyzed from a bilateral perspective between China and the Philippines. A theoretical analysis of the dispute has been conducted through a Neorealist paradigm. How the two countries define international law and engage in diplomatic and military policies has also been closely examined. China has not sought foreign intervention whether from a nation or international organization, while the Philippines has preferred as much multilateralism as possible. A recent Scarborough Shoal dispute between the two countries has changed the dynamic of the dispute, and in examining the event and its outcome an inevitable conclusion of military action has been reached.
This study develops a framework for pricing output traits derived from agriculture biotechnology and the effects on competing technologies post-introduction of the genetically modified (GM) variety. ...The price impact model determines processor or consumer adoption rates and changes in processor, farmer, and tech firm surplus as a result of the release of the new GM variety. Several implications result from this research. First, adoption of the GM variety may not be as high as expected due to the lower cost of using conventional varieties for processing or consumption inputs. Second, both processors who adopt the GM variety and those who continue to use conventional varieties will have an increase in surplus as a result;
of the introduction of the GM variety. Lower costs of conventional varieties will also result in new entrants into the market.
A current body of research is finding significant connection between biological, psychological, social, and spiritual factors in health and wellbeing. Some studies have found significant improvements ...in treatment outcomes for patients who received medical treatment in collaboration with psychosocial therapeutic treatment. In this study, I sought to observe the impact collaborative treatment had on patients with diabetes who were treated at a community health center. I compared the treatment outcomes of a group of patients who received a collaborative treatment, looking to see if their overall health (measured by A1c, a diabetes severity marker) and medical utilization (or their number of doctors’ visits).
I found no significant difference in the improvements in health outcomes (A1c) made by my treatment group who received collaborative treatment in addition to standard medical treatment for diabetes management when compared to my control group who received only medical treatment. I did find that collaborative treatment was associated with increases in medical utilization as were increases in age and initial A1c levels. Clinical implications include the need for therapists to be aware of how biological factors, such as age and severity of symptoms, may affect psychosocial-spiritual factors commonly addressed in therapy when working with patients who have chronic illnesses like diabetes. I hope that these findings will lead future research into the association of collaboration and medical utilization in order to find if there are any clinical benefits to recommending increased utilization for patients who are older or begin treatment with higher A1c levels.
This thesis presents a research project aimed at advancing the treatment of cold-formed steel (CFS) structural reliability in roof trusses. Structural design today relies almost exclusively on ...component-level design, so structural safety is assured by limiting the probability of failure of individual components. Reliability of the entire system is typically not assessed, so in a worst-case scenario the system reliability may be less than the component reliability, or in a best-case scenario the system reliability may be much greater than the component reliability. A roof truss itself, is a subsystem with several possible failure modes that are being studied in this test program. These trusses are constructed of CFS members that nest with one another at the truss nodes and are connected by drilling fasteners through the mated surfaces, as well as having steel sheathing fastened to the top chords for lateral bracing. Presented in this paper is a series of full-scale static tests on single cold-formed steel roof trusses with a unique experimental setup. The test specimens were carefully monitored to address multiple failure modes: buckling of the top chord, buckling of the truss webs, and any connection failures. This research includes the experimental results, the computed system reliability of the trusses as well as their relationship between the components reliability.
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