Intra- and interspecies interactions between prion proteins and effects of mutations and polymorphisms

Recently, crystallization of the prion protein in a dimeric form was reported. Here we show that native soluble homogenous FLAG-tagged prion proteins from hamster, man and cattle expressed in the baculovirus system are predominantly dimeric. The PrP/PrP interaction was confirmed in Semliki Forest virus-RNA transfected BHK cells co-expressing FLAG- and oligohistidine-tagged human PrP. The yeast two-hybrid system identified the octarepeat region and the C-terminal structured domain (aa90-aa230) of PrP as PrP/PrP interaction domains. Additional octarepeats identified in patients suffering from fCJD reduced (wtPrP versus PrP+90R) and completely abolished (PrP+90R versus PrP+90R) the PrP/PrP interaction in the yeast two-hybrid system. In contrast, the Met/Val polymorphism (aa129), the GSS mutation Pro102Leu and the FFI mutation Asp178Asn did not affect PrP/PrP interactions. Proof of interactions between human or sheep and bovine PrP, and sheep and human PrP, as well as lack of interactions between human or bovine PrP and hamster PrP suggest that interspecies PrP interaction studies in the yeast two-hybrid system may serve as a rapid pre-assay to investigate species barriers in prion diseases

Evaluating a hybrid soil temperature model in a corn-soybean agroecosystem and a tallgrass prairie in the Great plains

Simulation models of soil-related biological processes usually require soil temperature data. Frequently these soil temperatures are simulated, and the soil temperature algorithms cannot be more complicated than the original process model. This situation has led to the use of semi-empirical-type relationships in these process models. The objective of this study was to evaluate a hybrid soil temperature model, which combines empirical and mechanistic approaches, in an agroecosystem and a tallgrass prairie in the Great Plains. The original hybrid soil temperature model was developed and verified for a temperate forest system. This model simulated soil temperatures on a daily basis from meteorological inputs (maximum and minimum air temperatures) and soil and plant properties. This model was modified using different extinction coefficients for the plant canopy and ground litter. The agroecosystem consisted of a no-till rotation system of corn (Zea mays L.) and soybeans (Glycine max [L.] Merr.). Soil temperatures were measured at different depths in multiple years (three years and two-and-a-half years in the agroecosystem and tallgrass prairie, respectively). In the agroecosystem, the root mean square error of the modified model simulation varied from 1.41º to 2.05ºC for the four depths (0.1, 0.2, 0.3, and 0.5 m). The mean absolute error varied from 1.06º to 1.53ºC. The root mean square error and mean absolute error of the modified model were about 0.1º–0.3ºC less than the original model at the 0.2–0.5 m depths. For the tallgrass prairie, the mean absolute errors of the simulated soil temperatures were slightly greater than the agroecosystem, varying from 1.48º to 1.7ºC for all years and from 1.09º to 1.37ºC during the active growing seasons for all years.EEA OliverosFil: Song, Feng. University of Nebraska–Lincoln. School of Natural Resources; Estados UnidosFil: Salvagiotti, Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Oliveros. Departamento de Agronomía; ArgentinaFil: Schmer, M.R. University of Nebraska–Lincoln. Department of Agronomy and Horticulture; Estados UnidosFil: Wingeyer, Ana Beatriz. University of Nebraska–Lincoln. Department of Agronomy and Horticulture; Estados UnidosFil: Weiss, Albert. University of Nebraska–Lincoln. School of Natural Resources; Estados Unido

Interacting Random Walkers and Non-Equilibrium Fluctuations

We introduce a model of interacting Random Walk, whose hopping amplitude depends on the number of walkers/particles on the link. The mesoscopic counterpart of such a microscopic dynamics is a diffusing system whose diffusivity depends on the particle density. A non-equilibrium stationary flux can be induced by suitable boundary conditions, and we show indeed that it is mesoscopically described by a Fourier equation with a density dependent diffusivity. A simple mean-field description predicts a critical diffusivity if the hopping amplitude vanishes for a certain walker density. Actually, we evidence that, even if the density equals this pseudo-critical value, the system does not present any criticality but only a dynamical slowing down. This property is confirmed by the fact that, in spite of interaction, the particle distribution at equilibrium is simply described in terms of a product of Poissonians. For mesoscopic systems with a stationary flux, a very effect of interaction among particles consists in the amplification of fluctuations, which is especially relevant close to the pseudo-critical density. This agrees with analogous results obtained for Ising models, clarifying that larger fluctuations are induced by the dynamical slowing down and not by a genuine criticality. The consistency of this amplification effect with altered coloured noise in time series is also proved.Comment: 8 pages, 7 figure

Hormonal therapy of menopause: 2004 position of the Department of Female Endocrinology and Andrology of the Brazilian Society of Endocrinology and Metabolism

After randomized clinical trials produced impact and questions at the medical community on menopause hormonal therapy (MHT), the Department of Female Endocrinology and Andrology of the Brazilian Society of Endocrinology convened a group of specialists to produce an informative, critical and position paper, offering guidelines for those who practice or are called to express their opinion on menopause therapy. MHT is indicated for relief of vasomotor symptoms, maintenance of vaginal trophism, bone mass and collagen preservation, sexual and general well-being. Studies on primary cardiovascular prevention are not conclusive, and thus insufficient to indicate or not MHT for this purpose. Schemes and forms of association should de individualized. Whenever possible, one should use 17-beta estradiol, associated to natural progesterone or its derivatives in women with an intact uterus, at the lowest effective doses. Duration of therapy depends on its aims, and should be periodically re-evaluated through an individual indication/contra-indication balance. Orientation toward a healthier lifestyle, with smoking cessation, adequate calcium intake and a low fat diet, together with regular physical activity is fundamental during menopause.Após os estudos clínicos randomizados produzirem impacto e questionamentos sobre terapia hormonal da menopausa (THM) na comunidade médica, o Departamento de Endocrinologia Feminina e Andrologia da SBEM reuniu um grupo de especialistas para formular um documento informativo, crítico e de posicionamento que pudesse servir de orientação aos que praticam ou opinam sobre tratamento da menopausa. THM está indicada para alívio dos sintomas motores, conservação do trofismo vaginal, preservação de massa óssea e colágeno, melhora do bem estar e sexualidade. Os estudos sobre prevenção cardiovascular primária não são conclusivos, portanto insuficientes para indicar ou deixar de indicar THM com este objetivo. Esquemas e tipos de associação devem ser individualizados. Sempre que possível deve-se optar pelas menores doses eficazes de 17-beta estradiol, associado a progesterona natural ou seus derivados nas mulheres com útero. A duração do tratamento é vinculada a seus objetivos, devendo ser reavaliada periodicamente através de um balanço individual entre indicação e contra-indicação. Orientação quanto a um estilo de vida mais saudável, com eliminação de tabagismo, alimentação adequada em cálcio e pobre em gorduras e atividade física regular são fundamentais como cuidados associados durante a menopausa.Ministério da Saúde Setor de Endocrinologia Hospital da LagoaInstituto Estadual de Diabetes e EndocrinologiaUniversidade do Estado do Rio de JaneiroMinistério da Saúde FIOCRUZ Instituto Fernandes FigueiraUniversidade Federal de São Paulo (UNIFESP)UNIFESPSciEL

Static properties of nuclear matter within the Boson Loop Expansion

The use of the Boson Loop Expansion is proposed for investigating the static properties of nuclear matter. We explicitly consider a schematic dynamical model in which nucleons interact with the scalar-isoscalar sigma meson. The suggested approximation scheme is examined in detail at the mean field level and at the one- and two-loop orders. The relevant formulas are provided to derive the binding energy per nucleon, the pressure and the compressibility of nuclear matter. Numerical results of the binding energy at the one-loop order are presented for Walecka's sigma-omega model in order to discuss the degree of convergence of the Boson Loop Expansion.Comment: 40 pages, 13 figure

What do young athletes implicitly understand about psychological skills?

One reason sport psychologists teach psychological skills is to enhance performance in sport; but the value of psychological skills for young athletes is questionable because of the qualitative and quantitative differences between children and adults in their understanding of abstract concepts such as mental skills. To teach these skills effectively to young athletes, sport psychologists need to appreciate what young athletes implicitly understand about such skills because maturational (e.g., cognitive, social) and environmental (e.g., coaches) factors can influence the progressive development of children and youth. In the present qualitative study, we explored young athletes’ (aged 10–15 years) understanding of four basic psychological skills: goal setting, mental imagery, self-talk, and relaxation. Young athletes (n = 118: 75 males and 43 females) completed an open-ended questionnaire to report their understanding of these four basic psychological skills. Compared with the older youth athletes, the younger youth athletes were less able to explain the meaning of each psychological skill. Goal setting and mental imagery were better understood than self-talk and relaxation. Based on these findings, sport psychologists should consider adapting interventions and psychoeducational programs to match young athletes’ age and developmental level

Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold

X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the Kramers-Kronig transformation, correspond to a magneto-optical Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.Comment: 4 pages, 2 figures, final version resubmitted to Phys. Rev. B, Brief Reports. Minor change

The identification of salient beliefs concerning university students’ decision to participate in sport

The aim of this study was to identify salient beliefs toward university-provided recreational sport in first-year undergraduate students. A purposive sample of 76 students (36 males, 40 females; mean age: 19.2 ± 1.7 years) undertaking various degree subjects at a higher education institution in the North of England, United Kingdom, was used in the study. The instrument was a theory-based open-ended questionnaire informed by the Theory of Planned Behavior, addressing behavioral, normative, and control beliefs. Thematic content analysis and coding was conducted on 30 randomly selected questionnaires followed by a frequency count to identify the modal salient beliefs. The modal set revealed 17 beliefs from a possible 53: six behavioral, five normative, and six control. These beliefs were related to health benefits, enjoyment, friendships, time constraints, study workloads, awareness, and the perception of family, friends, and academics. The results highlight the factors that should be targeted for intervention and provide data to be utilized for a second main quantitative study which will identify more specific belief targets. Due to equivocal intervention success, this formative research can serve to help increase the number of students participating in university recreational spor

Simulating dynamic fire regime and vegetation change in a warming Siberia

Background Climate change is expected to increase fire activity across the circumboreal zone, including central Siberia. However, few studies have quantitatively assessed potential changes in fire regime characteristics, or considered possible spatial variation in the magnitude of change. Moreover, while simulations indicate that changes in climate are likely to drive major shifts in Siberian vegetation, knowledge of future forest dynamics under the joint influence of changes in climate and fire regimes remains largely theoretical. We used the forest landscape model, LANDIS-II, with PnET-Succession and the BFOLDS fire extension to simulate changes in vegetation and fire regime characteristics under four alternative climate scenarios in three 10,000-km2 study landscapes distributed across a large latitudinal gradient in lowland central Siberia. We evaluated vegetation change using the fire life history strategies adopted by forest tree species: fire resisters, fire avoiders, and fire endurers. Results Annual burned area, the number of fires per year, fire size, and fire intensity all increased under climate change. The relative increase in fire activity was greatest in the northernmost study landscape, leading to a reduction in the difference in fire rotation period between study landscapes. Although the number of fires per year increased progressively with the magnitude of climate change, mean fire size peaked under mild or moderate climate warming in each of our study landscapes, suggesting that fuel limitations and past fire perimeters will feed back to reduce individual fire extent under extreme warming, relative to less extreme warming scenarios. In the Southern and Mid-taiga landscapes, we observed a major shift from fire resister-dominated forests to forests dominated by broadleaved deciduous fire endurers (Betula and Populus genera) under moderate and extreme climate warming scenarios, likely associated with the substantial increase in fire activity. These changes were accompanied by a major decrease in average cohort age and total vegetation biomass across the simulation landscapes. Conclusions Our results imply that climate change will greatly increase fire activity and reduce spatial heterogeneity in fire regime characteristics across central Siberia. Potential ecological consequences include a widespread shift toward forests dominated by broadleaved deciduous species that employ a fire endurer strategy to persist in an increasingly fire-prone environment