17,453 research outputs found

    Gulf War Syndrome: A role for organophosphate induced plasticity of locus coeruleus neurons

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    Gulf War syndrome is a chronic multi-symptom illness that has affected about a quarter of the deployed veterans of the 1991 Gulf War. Exposure to prolonged low-level organophosphate insecticides and other toxic chemicals is now thought to be responsible. Chlorpyrifos was one commonly used insecticide. The metabolite of chlorpyrifos, chlorpyrifos oxon, is a potent irreversible inhibitor of acetylcholinesterase, much like the nerve agent Sarin. To date, the target brain region(s) most susceptible to the neuroactive effects of chlorpyrifos oxon have yet to be identified. To address this we tested ability of chlorpyrifos oxon to influence neuronal excitability and induce lasting changes in the locus coeruleus, a brain region implicated in anxiety, substance use, attention and emotional response to stress. Here we used an ex vivo rodent model to identify a dramatic effect of chlorpyrifos oxon on locus coeruleus noradrenergic neuronal activity. Prolonged exposure to chlorpyrifos oxon caused acute inhibition and a lasting rebound excitatory state expressed after days of exposure and subsequent withdrawal. Our findings indicate that the locus coeruleus is a brain region vulnerable to chlorpyrifos oxon-induced neuroplastic changes possibly leading to the neurological symptoms affecting veterans of the Gulf War

    mGluR5 knockout mice exhibit normal conditioned place-preference to cocaine

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    Metabotropic glutamate receptor 5 (mGluR5) null mutant (-/-) mice have been reported to totally lack the reinforcing or locomotor stimulating effects of cocaine. We tested mGluR5 -/- and +/+ mice for their locomotor and conditioned place- preference response to cocaine. Unlike the previous finding, here we show that compared to mGluR5 +/+ mice, -/- mice exhibit no difference in the locomotor response to low to moderate doses of cocaine (10 or 20 mg/kg). A high dose of cocaine (40 mg/kg) resulted in a blunted rather than absent locomotor response. We tested mGluR5 -/- and +/+ mice for conditioned place-preference to cocaine and found no group differences at a conditioning dose of 10 mg/kg, suggesting normal conditioned rewarding properties of cocaine. These results differ substantially from Chiamulera et al. (2001) and replicates Olsen et al., (2010), who found normal cocaine place-preference in mGluR5 -/- mice at 5 mg/kg. Our results indicate mGluR5 receptors exert a modulatory rather than necessary role in cocaine-induced locomotor stimulation and exert no effect on the conditioned rewarding effects of cocaine

    Local Public Services in Wisconsin: Alternatives for Municipalities with a Focus on Privatization

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    Both rural and urban municipal officials, faced with increased local resistance to higher taxes, increasing expenditure needs, weakening financial support from higher levels of government, and the growing pressure to "do more with less" have accelerated their search for alternative ways of delivering local public services. The downsizing of government has been brought to the forefront of public discussion in part due to the general conservative shift at the federal and state level and the need to maintain a balanced budget at the local level. Related private sector trends downsizing middle management as a means to become "leaner and meaner," reducing duplication and waste, and increasing earnings, profit levels, and returns to investors. At the same time many local public officials are faced with rising costs to maintain an aging infrastructure, accommodating the needs of special populations, satisfying rules and regulations imposed by higher levels of government, funding new investments to meet the demands of a growing economy in some instances, or maintaining critical services in the face declining economies. In short, the rules of the game for effective management of local governments have changed.

    Nicotinic α7 acetylcholine receptor-mediated currents are not modulated by the tryptophan metabolite kynurenic acid in adult hippocampal interneurons

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    The  tryptophan  metabolite,  kynurenic  acid (KYNA),  is  classically  known  to  be  an antagonist  of ionotropic glutamate receptors. Within the last decade several reports have been published suggesting that KYNA also blocks nicotinic acetylcholine receptors (nAChRs) containing the α7 subunit (α7*). Most of these reports involve either indirect measurements of KYNA effects on α7 nAChR function, or are reports of KYNA effects in complicated in vivo systems.  However, a recent report investigating KYNA interactions with α7 nAChRs failed to detect an interaction using direct measurements of α7 nAChRs function.  Further, it showed that a KYNA blockade of α7 nAChR stimulated GABA release (an indirect measure of α7 nAChR function) was not due to KYNA blockade of the α7 nAChRs. The current study measured the direct effects of KYNA on α7-containing nAChRs expressed on interneurons in the hilar and CA1 stratum radiatum regions of the mouse hippocampus and on interneurons in the CA1 region of the rat hippocampus.  Here we show that KYNA does not block α7* nACHRs using direct patch-­clamp recording of α7 currents in adult brain slices

    Control over stress induces plasticity of individual prefrontal cortical neurons: A conductance-based neural simulation

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    Behavioral control over stressful stimuli induces resilience to future conditions when control is lacking. The medial prefrontal cortex(mPFC) is a critically important brain region required for plasticity of stress resilience. We found that control over stress induces plasticity of the intrinsic voltage-gated conductances of pyramidal neurons in the PFC. To gain insight into the underlying biophysical mechanisms of this plasticity we used the conductance- based neural simulation software tool, NEURON, to model the increase in membrane excitability associated with resilience to stress. A ball and stick multicompartment conductance-based model was used to realistically fit passive and active data traces from prototypical pyramidal neurons in neurons in rats with control over tail shock stress and those lacking control. The results indicate that the plasticity of membrane excitability associated with control over stress can be attributed to an increase in Na+ and Ca2+ T-type conductances and an increase in the leak conductance. Using simulated dendritic synaptic inputs we observed an increase in excitatory postsynaptic summation and amplification resulting in elevated action potential output. This realistic simulation suggests that control over stress enhances the output of the PFC and offers specific testable hypotheses to guide future electrophysiological mechanistic studies in animal models of resilience and vulnerability to stress

    Large Deployable Reflector (LDR) system concept and technology definition study. Analysis of space station requirements for LDR

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    A study was conducted to determine how the Large Deployable Reflector (LDR) might benefit from the use of the space station for assembly, checkout, deployment, servicing, refurbishment, and technology development. Requirements that must be met by the space station to supply benefits for a selected scenario are summarized. Quantitative and qualitative data are supplied. Space station requirements for LDR which may be utilized by other missions are identified. A technology development mission for LDR is outlined and requirements summarized. A preliminary experiment plan is included. Space Station Data Base SAA 0020 and TDM 2411 are updated

    Marketing Tips for Small-scale, Local Honey Bee Keepers in Northwest Arkansas

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    The objective of this thesis was to gain market information for beekeepers regarding different honey bee products and to provide information about economic feasibility when produced on a small, local scale. Since cost-of-production information about operating an apiary is widely available, the focus of this work was on gaining marketing knowledge. One of the objectives of the surveys was to develop a better sense of what potential resellers of honey bee products considered locally produced. Another objective was to determine preferences for honey bee product packaging as well as bee pollination services. Using that feedback, a marketing plan for different niche markets can be developed for part-time beekeeping operations. The survey results pertaining to local retailers and end users in Northwest Arkansas in 2016 suggested a supply radius near 100 miles and a preference for small packaging in general. Least cost supply, and at least regional brand recognition were not deemed as important as ensuring locally sourced products that can be sold at a premium. Different niche markets revealed both similar and different priorities related to these marketing aspects

    Dietary patterns among Vietnamese and Hispanic immigrant elementary school children participating in an after school program

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    Immigrants in the U.S. may encounter challenges of acculturation, including dietary habits, as they adapt to new surroundings. We examined Vietnamese and Hispanic immigrant children's American food consumption patterns in a convenience sample of 63 Vietnamese and Hispanic children in grades four to six who were attending an after school program. Children indicated the number of times they consumed each of 54 different American foods in the past week using a food frequency questionnaire. We ranked each food according to frequency of consumption, compared the intake of foods to the USDA Healthy Eating Pattern, and performed dietary pattern analysis. Since the data were not normally distributed we used two nonparametric tests to evaluate statistical significance: the Kruskal-Wallis tested for significant gender and ethnicity differences and the Wilcoxon signed-rank test evaluated the food consumption of children compared with the USDA recommended amounts. We found that among USDA categories, discretionary food was most commonly consumed, followed by fruit. The sample as a whole ate significantly less than the recommended amount of grains, protein foods, and dairy, but met the recommended amount of fruit. Boys ate significantly more grains, proteins, and fruits than did girls. Dietary pattern analysis showed a very high sweet snack consumption among all children, while boys ate more fast food and fruit than girls. Foods most commonly consumed were cereal, apples, oranges, and yogurt. Ethnicity differences in food selection were not significant. The high intake of discretionary/snack foods and fruit, with low intake of grains, vegetables, protein, and dairy in our sample suggests Vietnamese and Hispanic immigrant children may benefit from programs to improve diet quality

    Sociability is decreased following deletion of the _trpc4_ gene

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    Shyness and social anxiety are predominant features of some psychiatric disorders including autism, schizophrenia, anxiety and depression. Understanding the cellular and molecular determinants of sociability may reveal therapeutic approaches to treat individuals with these disorders and improve their quality of life. Previous experiments from our laboratory have identified selective mRNA and protein expression of a nonselective cation channel known as the canonical transient receptor potential channel 4 (TRPC4s) in brain regions implicated in emotional regulation and anxiety. TRPC4 is highly expressed in the corticolimbic regions of the mammalian brain. We hypothesized that robust corticolimbic expression of TRPC4 may regulate the brain’s response to emotion and anxiety resulting in changes in social interaction. Here we test trpc4 gene knockout rats in a model of social anxiety/interaction. We found that the Trpc4 knockout animals spent significantly less time exploring a juvenile intruder rat compared to their wild-type counterparts and Sprague-Dawley (SD) rats. Furthermore, Trpc4 wild-type (Fisher 344) rats explored the juvenile significantly less than the SD rats. These findings indicate that the _trpc4_ gene plays a role in modulating cellular excitability in specific regions of the brain associated sociality and/or anxiety

    AN EMPIRICAL TEST FOR THE EXPANSION-CONTROL MODEL FOR MANAGING END-USER COMPUTING

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    The purpose of this research is to determine if the expansion-control model as proposed, adapted, and refined (Munro and Huff 1985; Munro, Huff and Moore 1987) is useful for understanding and predicting changes in EUC management strategy over time. The long-term interest is not so much in understanding the specific problem of managing end-user computing as in understanding the general problem of managing new information technology in organizations. A field study was conducted with eighteen large firms in manufacturing and services to review their experience with EUC management over a nine year period. As predicted, most firms took a hands-off approach to EUC management during the initiation phase and evolved toward a balance between control and slack by 1987. However, changes in firms\u27 EUC management strategy over time were more complex than predicted. In addition, the expansion and control constructs were not as independent as previously thought. The interaction between the two variables appears to be related, at least in part, to time and the stage of diffusion. The research suggests that current models of EUC management (and thus organizational learning about information technology) may be too simplistic. Suggestions for developing more general models of the process are offered
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