Nutrient Concentrations at Baseflow Conditions in the Upper White River Basin, Southwest Missouri and Northwest Arkansas

The Upper White River Basin (UWRB) is becoming increasingly vulnerable to water quality degradation from urban/population growth and increased agricultural production. This study examines the relationships among nutrient levels, water chemistry and watershed characteristics of 19 watersheds in the UWRB. Water samples were collected during baseflow conditions each month for one year at USGS continuous-flow gage stations. Watershed characteristics evaluated were land use, geology, drainage area, flow discharge, and wastewater treatment plant discharge (WTP). Measured chemical water quality indicators include total nitrogen (TN), total phosphorus (TP), specific conductivity, turbidity, pH and dissolved oxygen. Rapidly expanding urban areas are associated with relatively high nutrient concentrations at baseflow such as found in the James River Basin, where mean levels range from 0.9 to 11.7 mg/L for TN and 18 to 175 μg/L for TP. Nutrient concentrations have a strong positive correlation to specific WTP discharge (gal/day/km²). Non-point source-affected watersheds with no or only slight WTP inputs show a negative relationship between percent forest cover and nutrient concentrations. Higher nutrient concentrations are found in watersheds with less than 50% forest in non-point source watersheds, although these nutrient levels remain below the James River recommended Total Maximum Daily Load ( \u3c 75 μg/L TP and \u3c 1.5 mg/L TN). Agricultural watersheds ( \u3e 50% ag land) in karst limestone plain areas also show elevated nutrient concentrations ranging from 0.4 to 5.2 mg/L for TN and 9 to 103 μg/L for TP

Rodent Aβ Modulates the Solubility and Distribution of Amyloid Deposits in Transgenic Mice

The amino acid sequence of amyloid precursor protein (APP) is highly conserved, and age-related Abeta aggregates have been described in a variety of vertebrate animals, with the notable exception of mice and rats. Three amino acid substitutions distinguish mouse and human Abeta that might contribute to their differing properties in vivo. To examine the amyloidogenic potential of mouse Abeta, we studied several lines of transgenic mice overexpressing wild-type mouse amyloid precursor protein (moAPP) either alone or in conjunction with mutant PS1 (PS1dE9). Neither overexpression of moAPP alone nor co-expression with PS1dE9 caused mice to develop Alzheimer-type amyloid pathology by 24 months of age. We further tested whether mouse Abeta could accelerate the deposition of human Abeta by crossing the moAPP transgenic mice to a bigenic line expressing human APPswe with PS1dE9. The triple transgenic animals (moAPP x APPswe/PS1dE9) produced 20% more Abeta but formed amyloid deposits no faster and to no greater extent than APPswe/PS1dE9 siblings. Instead, the additional mouse Abeta increased the detergent solubility of accumulated amyloid and exacerbated amyloid deposition in the vasculature. These findings suggest that, although mouse Abeta does not influence the rate of amyloid formation, the incorporation of Abeta peptides with differing sequences alters the solubility and localization of the resulting aggregates

Persistent Amyloidosis following Suppression of Aβ Production in a Transgenic Model of Alzheimer Disease

BACKGROUND: The proteases (secretases) that cleave amyloid-β (Aβ) peptide from the amyloid precursor protein (APP) have been the focus of considerable investigation in the development of treatments for Alzheimer disease. The prediction has been that reducing Aβ production in the brain, even after the onset of clinical symptoms and the development of associated pathology, will facilitate the repair of damaged tissue and removal of amyloid lesions. However, no long-term studies using animal models of amyloid pathology have yet been performed to test this hypothesis. METHODS AND FINDINGS: We have generated a transgenic mouse model that genetically mimics the arrest of Aβ production expected from treatment with secretase inhibitors. These mice overexpress mutant APP from a vector that can be regulated by doxycycline. Under normal conditions, high-level expression of APP quickly induces fulminant amyloid pathology. We show that doxycycline administration inhibits transgenic APP expression by greater than 95% and reduces Aβ production to levels found in nontransgenic mice. Suppression of transgenic Aβ synthesis in this model abruptly halts the progression of amyloid pathology. However, formation and disaggregation of amyloid deposits appear to be in disequilibrium as the plaques require far longer to disperse than to assemble. Mice in which APP synthesis was suppressed for as long as 6 mo after the formation of Aβ deposits retain a considerable amyloid load, with little sign of active clearance. CONCLUSION: This study demonstrates that amyloid lesions in transgenic mice are highly stable structures in vivo that are slow to disaggregate. Our findings suggest that arresting Aβ production in patients with Alzheimer disease should halt the progression of pathology, but that early treatment may be imperative, as it appears that amyloid deposits, once formed, will require additional intervention to clear

UK science press officers, professional vision and the generation of expectations

Science press officers can play an integral role in helping promote expectations and hype about biomedical research. Using this as a starting point, this article draws on interviews with 10 UK-based science press officers, which explored how they view their role as science reporters and as generators of expectations. Using Goodwin’s notion of ‘professional vision’, we argue that science press officers have a specific professional vision that shapes how they produce biomedical press releases, engage in promotion of biomedical research and make sense of hype. We discuss how these insights can contribute to the sociology of expectations, as well as inform responsible science communication.This project was funded by the Wellcome Trust (Wellcome Trust Biomedical Strategic Award 086034)

Environmental Enrichment Mitigates Cognitive Deficits in a Mouse Model of Alzheimer's Disease

Epidemiological studies suggest that individuals with greater education or more cognitively demanding occupations have diminished risk of developing dementia. We wanted to test whether this effect could be recapitulated in rodents using environmental enrichment, a paradigm well documented to attenuate behavioral deficits induced by various pathological insults. Here, we demonstrate that learning and memory deficits observed in a transgenic mouse model of Alzheimer's disease can be ameliorated by enrichment. Female transgenic mice overexpressing amyloid precursor protein and/or presenilin-1 and nontransgenic controls were placed into enriched or standard cages at 2 months of age and tested for cognitive behavior after 6 months of differential housing. Enrichment significantly improved performance of all genotypes in the radial water maze and in the classic and repeated-reversal versions of the Morris water maze. However, enrichment did not benefit all genotypes equally. Mice overproducing amyloid-β (Aβ), particularly those with amyloid deposits, showed weaker memory for the platform location in the classic Morris water maze and learned new platform positions in the repeated-reversals task less quickly than their nontransgenic cagemates. Nonetheless, enrichment normalized the performance of Aβ-overproducing mice to the level of standard-housed nontransgenic mice. Moreover, this functional preservation occurred despite increased neuritic plaque burden in the hippocampus of double-transgenic animals and elevated steady-state Aβ levels, because both endogenous and transgene-derived Aβ are increased in enriched animals. These results demonstrate that the generation of Aβ in vivo and its impact on the function of the nervous system can be strongly modulated by environmental factors

Human Germline Genetic Modification: Issues and Options for Policymakers

Germline genetic modification is possible in animals, but not yet in humans. If certain technical obstacles were overcome, human germline genetic modification (HGGM) could allow human beings to create permanent heritable genetic changes in their descendants by changing the genetic makeup of human eggs or sperm, or human embryos at the earliest stages. For many decades, the technical barriers to HGGM have seemed insurmountable. Today, however, advances in human reproductive technologies, stem cell science, and animal genetic modification have brought the possibility of HGGM much nearer than it has been before. The Genetics and Public Policy Center believes it is time for renewed consideration of this controversial subject. This report, Human Germline Genetic Modification: Issues and Options for Policymakers, analyzes the scientific, legal, regulatory, ethical, moral, and societal issues raised by genetic modification of the human germline, provides data about the American public’s views about HGGM, and explores possible policy approaches in this area. Science Germline genetic modification is possible in laboratory animals, and some techniques could be translated for use in humans although none has been tried. Scientists are able to replace a faulty gene with a “normal” copy in mouse embryonic stem cells, then introduce those stem cells into an early mouse embryo where they can give rise to genetically modified sperm or eggs. The next generation of mice that results from the modified sperm or eggs will contain the “normal” copy of the gene. It is now possible to replace a gene in human embryonic stem cells, overcoming a huge obstacle to HGGM. In addition, scientists have been able to derive genetically modified sperm directly from mouse stem cells. Together, these developments suggest that HGGM may not be as far off as we thought even five years ago. While advances in these techniques have been driven by more general research goals widely viewed as valuable, and not the pursuit of HGGM specifically, these discoveries will catapult us over what were understood to be the principal technical obstacles to HGGM. Safety Serious consideration of safety is and has been of utmost importance in any deliberation about HGGM. In animal research, many germline genetic modification approaches can introduce unwanted mutations that can lead to severe developmental outcomes, even death. Most safety risks of HGGM would be to the resulting child. The proposed techniques for HGGM involve extensive manipulation of stem cells, eggs, sperm, or embryos in the laboratory prior to introduction into a woman’s uterus. Such manipulation alone could alter the growth and development of the fetus in ways that are not yet well understood, resulting in health problems that in many cases could be lethal. There is a clear need for more animal research and better data, although it is less clear how much and what it would need to show. Many questions exist about how to measure the risks and benefits of HGGM. And although it is a basic tenet of medical practice that patients receiving medical treatment must provide informed consent, opinions are divided as to whether and when the consent of the true “patients” — the future child and future generations — could and should be assumed. Scenarios HGGM may become more technically feasible in the future. The question remains whether and for what purpose HGGM would be attempted. Many first applications could be imagined for HGGM and the technical feasibility and perceived demand are different for each. An example of a technically more feasible use of HGGM with low demand would be its use to prevent recessive genetic disease such as cystic fibrosis. This is more technically feasible because the single-gene mutations have been identified. However, since these diseases can be avoided by other already existing techniques, such as PGD, the perceived demand for using HGGM would be low. An example of a technically less feasible use of HGGM with unclear demand would be its use to enhance traits such as intelligence or strength. This is less technically feasible because the genetics behind these traits are largely unknown. The perceived demand is unclear because of the many ethical questions surrounding the use of HGGM for enhancement. In contrast, there may be fewer ethical objections to — and more demand for — using HGGM to enhance human health, to provide a “vaccine” against HIV for example. Feasibility would depend on both an understanding of the genetic disease at issue and the overall development of safe and efficient methods for HGGM. A table analyzing eight possible scenarios for HGGM is presented in the report. Public Opinion Until now, the most sustained and visible deliberations about HGGM have been within elite governmental commissions or academic institutions. Frequently, these groups have called for increased public input in the discussion, but there has been little public engagement in the issue outside of the extreme portrayals of HGGM by Hollywood or the popular press. As a result, little has been known about the views of the general public. In order to learn more about what the American public knows, thinks, and feels about HGGM and other reproductive genetic technologies, the Genetics and Public Policy Center recently conducted a broad survey of 4,834 Americans. Our data show significant interest in HGGM as a potential means for avoiding serious genetic disease. However, concerns were expressed about how safe the technology would be, who would have access to it and who would not, and the impact of HGGM on society as a whole. Ethics The purposes for which HGGM might be attempted vary, from “fixing” a genetic mutation before an individual is born to enhancing children with socially desirable traits such as athletic skill or intelligence. Views differ as to which purposes are ethically acceptable and whether it is possible to meaningfully distinguish, for example, between a “therapeutic” use of HGGM on the one hand and an “enhancement” use on the other. A vast array of ethical issues arises from HGGM. HGGM raises both the specter of humans “playing God” and questions about whether such interventions in nature would change the human gene pool, ultimately affecting the species as a whole. There are fears that HGGM will negatively affect human dignity and attitudes towards those living with disabilities, casting people as “problems” that could have been avoided and putting pressure on families to have genetically “perfect” children. Some question whether HGGM would start society on a slippery slope to a modern version of eugenics, regardless of the purposes for which it would be used. And for those who categorically oppose manipulation or destruction of human embryos, HGGM would be unacceptable under any circumstances because it would involve one or both for the foreseeable future. Oversight In the United States, both the Food and Drug Administration (FDA) and the Recombinant DNA Advisory Committee (RAC) of the National Institutes of Health (NIH) play a role in current federal oversight of HGGM. FDA has indicated that it would treat any proposals for HGGM the same way it treats proposals for somatic gene modification, and require an investigational new drug application (IND) to be filed before the technology may be attempted in humans. It is unclear what criteria FDA would use to evaluate such an application. At the present time, the RAC has indicated that it will not consider any proposals for HGGM. Options An array of policy approaches is available for future oversight of HGGM. Policymakers and the public may consider a direct ban of HGGM; increased oversight with an eye towards safety, ethical use, or both; or promotion of HGGM by providing additional resources for relevant research. International laws, United States law and regulation, and voluntary self-regulation by scientists are some of the approaches that are described, along with the advantages and disadvantages of each. Although HGGM remains on the distant horizon, technologic advances are bringing HGGM from the imaginable to the possible. Thus it is time to consider the difficult questions about HGGM. An enriched and expanded discussion that includes both experts and the public offers an opportunity to share information and understanding about the underlying values and concerns that inform our individual and collective perspectives on HGGM. Such an approach ultimately will lead to thoughtful and robust public policies

Synthesis and structural characterization of a mimetic membrane-anchored prion protein

During pathogenesis of transmissible spongiform encephalopathies (TSEs) an abnormal form (PrPSc) of the host encoded prion protein (PrPC) accumulates in insoluble fibrils and plaques. The two forms of PrP appear to have identical covalent structures, but differ in secondary and tertiary structure. Both PrPC and PrPSc have glycosylphospatidylinositol (GPI) anchors through which the protein is tethered to cell membranes. Membrane attachment has been suggested to play a role in the conversion of PrPC to PrPSc, but the majority of in vitro studies of the function, structure, folding and stability of PrP use recombinant protein lacking the GPI anchor. In order to study the effects of membranes on the structure of PrP, we synthesized a GPI anchor mimetic (GPIm), which we have covalently coupled to a genetically engineered cysteine residue at the C-terminus of recombinant PrP. The lipid anchor places the protein at the same distance from the membrane as does the naturally occurring GPI anchor. We demonstrate that PrP coupled to GPIm (PrP-GPIm) inserts into model lipid membranes and that structural information can be obtained from this membrane-anchored PrP. We show that the structure of PrP-GPIm reconstituted in phosphatidylcholine and raft membranes resembles that of PrP, without a GPI anchor, in solution. The results provide experimental evidence in support of previous suggestions that NMR structures of soluble, anchor-free forms of PrP represent the structure of cellular, membrane-anchored PrP. The availability of a lipid-anchored construct of PrP provides a unique model to investigate the effects of different lipid environments on the structure and conversion mechanisms of PrP

Abnormal cognition, sleep, EEG and brain metabolism in a novel knock-in Alzheimer mouse, PLB1

Peer reviewedPublisher PD

Heteroreceptor complexes formed by dopamine D1, histamine H3 and N-methyl-D-aspartate glutamate receptors as targets to prevent neuronal death in Alzheimer's disease

Alzheimer’s disease (AD) is a neurodegenerative disorder causing progressive memory loss and cognitive dysfunction. Anti-AD strategies targeting cell receptors consider them as isolated units. However, many cell surface receptors cooperate and physically contact each other forming complexes having different biochemical properties than individual receptors. We here report the discovery of dopamine D , histamine H , and N-methylD-aspartate (NMDA) glutamate receptor heteromers in heterologous systems and in rodent brain cortex. Heteromers were detected by coimmunoprecipitation and in situ proximity ligation assays (PLA) in the rat cortex where H receptor agonists, via negative cross-talk, and H receptor antagonists, via cross-antagonism, decreased D receptor agonist signaling determined by ERK1/2 or Akt phosphorylation and counteracted D receptormediated excitotoxic cell death. Both D and H receptor antagonists also counteracted NMDA toxicity suggesting a complex interaction between NMDA receptors and D -H receptor heteromer function. Likely due to heteromerization, H receptors act as allosteric regulator for D and NMDA receptors. By bioluminescence resonance energy transfer (BRET), we demonstrated that D or H receptors form heteromers with NR1A/NR2B NMDA receptor subunits. D -H -NMDA receptor complexes were confirmed by BRET combined with fluorescence complementation. The endogenous expression of complexes in mouse cortex was determined by PLA and similar expression was observed in wild-type and APP/PS1 mice. Consistent with allosteric receptor-receptor interactions within the complex, H receptor antagonists reduced NMDA or D receptor-mediated excitotoxic cell death in cortical organotypic cultures. Moreover, H receptor antagonists reverted the toxicity induced by ß -amyloid peptide. Thus, histamine H receptors in D -H -NMDA heteroreceptor complexes arise as promising targets to prevent neurodegeneration

Increased Expression of PS1 Is Sufficient to Elevate the Level and Activity of γ-Secretase In Vivo

Increase in the generation and deposition of amyloid-β (Aβ) plays a central role in the development of Alzheimer's Disease (AD). Elevation of the activity of γ-secretase, a key enzyme required for the generation for Aβ, can thus be a potential risk factor in AD. However, it is not known whether γ-secretase can be upregulated in vivo. While in vitro studies showed that expression of all four components of γ-secretase (Nicastrin, Presenilin, Pen-2 and Aph-1) are required for upregulation of γ-secretase, it remains to be established as to whether this is true in vivo. To investigate whether overexpressing a single component of the γ-secretase complex is sufficient to elevate its level and activity in the brain, we analyzed transgenic mice expressing either wild type or familial AD (fAD) associated mutant PS1. In contrast to cell culture studies, overexpression of either wild type or mutant PS1 is sufficient to increase levels of Nicastrin and Pen-2, and elevate the level of active γ-secretase complex, enzymatic activity of γ-secretase and the deposition of Aβ in brains of mice. Importantly, γ-secretase comprised of mutant PS1 is less active than that of wild type PS1-containing γ-secretase; however, γ-secretase comprised of mutant PS1 cleaves at the Aβ42 site of APP-CTFs more efficiently than at the Aβ40 site, resulting in greater accumulation of Aβ deposits in the brain. Our data suggest that whereas fAD-linked PS1 mutants cause early onset disease, upregulation of PS1/γ-secretase activity may be a risk factor for late onset sporadic AD