270 research outputs found
Predictive use of the Maximum Entropy Production principle for Past and Present Climates
In this paper, we show how the MEP hypothesis may be used to build simple
climate models without representing explicitly the energy transport by the
atmosphere. The purpose is twofold. First, we assess the performance of the MEP
hypothesis by comparing a simple model with minimal input data to a complex,
state-of-the-art General Circulation Model. Next, we show how to improve the
realism of MEP climate models by including climate feedbacks, focusing on the
case of the water-vapour feedback. We also discuss the dependence of the
entropy production rate and predicted surface temperature on the resolution of
the model
Effects of long-term exposure of gelatinated and non-gelatinated cadmium telluride quantum dots on differentiated PC12 cells
Background: The inherent toxicity of unmodified Quantum Dots (QDs) is a major hindrance to their use in
biological applications. To make them more potent as neuroprosthetic and neurotherapeutic agents, thioglycolic
acid (TGA) capped CdTe QDs, were coated with a gelatine layer and investigated in this study with differentiated
pheochromocytoma 12 (PC12) cells. The QD - cell interactions were investigated after incubation periods of up to
17 days by MTT and APOTOX-Glo Triplex assays along with using confocal microscopy.
Results: Long term exposure (up to 17 days) to gelatinated TGA-capped CdTe QDs of PC12 cells in the course of
differentiation and after neurites were grown resulted in dramatically reduced cytotoxicity compared to nongelatinated
TGA-capped CdTe QDs.
Conclusion: The toxicity mechanism of QDs was identified as caspase-mediated apoptosis as a result of cadmium
leaking from the core of QDs. It was therefore concluded that the gelatine capping on the surface of QDs acts as a
barrier towards the leaking of toxic ions from the core QDs in the long term (up to 17 days)
Screening rules for growth to detect celiac disease: A case-control simulation study
Background: It is generally assumed that most patients with celiac disease (CD) have a slowed growth in terms of length (or height) and weight. However, the effectiveness of slowed growth as a tool for identifying children with CD is unknown. Our aim is to study the diagnostic efficiency of several growth criteria used to detect CD children. Methods: A case-control simulation study was carried out. Longitudinal length and weight measurements from birth to 2.5 years of age were used from three groups of CD patients (n = 134) (one group diagnosed by screening, two groups with clinical manifestations), and a reference group obtained from the Social Medical Survey of Children Attending Child Health Clinics (SMOCC) cohort (n = 2,151) in The Netherlands. The main outcome measures were sensitivity, specificity and positive predictive value (PPV) for each criterion. Results: Body mass index (BMI) performed best for the groups with clinical manifestations. Thirty percent of the CD children with clinical manifestations and two percent of the reference children had a BMI Standard Deviation Score (SDS) less than -1.5 and a decrease in BMI SDS of at least -2.5 (PPV = 0.85%). The growth criteria did not discriminate between the screened CD group and the reference group. Conclusion: For the CD children with clinical manifestations, the most sensitive growth parameter is a decrease in BMI SDS. BMI is a better predictor than weight, and much better than length or height. Toddlers with CD detected by screening grow normally at this stage of the disease
An A2A adenosine receptor agonist, ATL313, reduces inflammation and improves survival in murine sepsis models
<p>Abstract</p> <p>Background</p> <p>The pathophysiology of sepsis is due in part to early systemic inflammation. Here we describe molecular and cellular responses, as well as survival, in A<sub>2A </sub>adenosine receptor (AR) agonist treated and untreated animals during experimental sepsis.</p> <p>Methods</p> <p>Sepsis was induced in mice by intraperitoneal inoculation of live bacteria (<it>Escherichia coli </it>or <it>Staphylococcus aureus</it>) or lipopolysaccharide (LPS). Mice inoculated with live bacteria were treated with an A<sub>2A </sub>AR agonist (ATL313) or phosphate buffered saline (PBS), with or without the addition of a dose of ceftriaxone. LPS inoculated mice were treated with ATL313 or PBS. Serum cytokines and chemokines were measured sequentially at 1, 2, 4, 8, and 24 hours after LPS was administered. In survival studies, mice were followed until death or for 7 days.</p> <p>Results</p> <p>There was a significant survival benefit in mice infected with live <it>E. coli </it>(100% vs. 20%, <it>p </it>= 0.013) or <it>S. aureus </it>(60% vs. 20%, <it>p </it>= 0.02) when treated with ATL313 in conjunction with an antibiotic versus antibiotic alone. ATL313 also improved survival from endotoxic shock when compared to PBS treatment (90% vs. 40%, <it>p </it>= 0.005). The serum concentrations of TNF-α, MIP-1α, MCP-1, IFN-γ, and IL-17 were decreased by ATL313 after LPS injection (<it>p </it>< 0.05). Additionally, ATL313 increased the concentration of IL-10 under the same conditions (<it>p </it>< 0.05). Circulating white blood cell concentrations were higher in ATL313 treated animals (<it>p </it>< 0.01).</p> <p>Conclusion</p> <p>Further studies are warranted to determine the clinical utility of ATL313 as a novel treatment for sepsis.</p
Influence of national culture on the adoption of integrated medical curricula
Integrated curricula have been implemented in medical schools all over the world. However, among countries different relative numbers of schools with integrated curricula are found. This study aims to explore the possible correlation between the percentage of medical schools with integrated curricula in a country and that country’s cultural characteristics. Curricula were defined as not integrated if in the first 2 years of the program at least two out of the three monodisciplinary courses Anatomy, Physiology and Biochemistry were identified. Culture was defined using Hofstede’s dimensions Power distance, Uncertainty avoidance, Masculinity/Femininity, and Individualism/Collectivism. Consequently, this study had to be restricted to the 63 countries included in Hofstede’s studies which harbored 1,195 medical schools. From each country we randomly sampled a maximum of 15 schools yielding 484 schools to be investigated. In total 91% (446) of the curricula were found. Correlation of percent integrated curricula and each dimension of culture was determined by calculating Spearman’s Rho. A high score on the Power distance index and a high score on the Uncertainty avoidance index correlated with a low percent integrated curricula; a high score on the Individualism index correlated with a high percent integrated curricula. The percentage integrated curricula in a country did not correlate with its score on the Masculinity index. National culture is associated with the propensity of medical schools to adopt integrated medical curricula. Consequently, medical schools considering introduction of integrated and problem-based medical curricula should take into account dimensions of national culture which may hinder the innovation process
Default-Mode-Like Network Activation in Awake Rodents
During wakefulness and in absence of performing tasks or sensory processing, the default-mode network (DMN), an intrinsic central nervous system (CNS) network, is in an active state. Non-human primate and human CNS imaging studies have identified the DMN in these two species. Clinical imaging studies have shown that the pattern of activity within the DMN is often modulated in various disease states (e.g., Alzheimer's, schizophrenia or chronic pain). However, whether the DMN exists in awake rodents has not been characterized. The current data provides evidence that awake rodents also possess ‘DMN-like’ functional connectivity, but only subsequent to habituation to what is initially a novel magnetic resonance imaging (MRI) environment as well as physical restraint. Specifically, the habituation process spanned across four separate scanning sessions (Day 2, 4, 6 and 8). At Day 8, significant (p<0.05) functional connectivity was observed amongst structures such as the anterior cingulate (seed region), retrosplenial, parietal, and hippocampal cortices. Prior to habituation (Day 2), functional connectivity was only detected (p<0.05) amongst CNS structures known to mediate anxiety (i.e., anterior cingulate (seed region), posterior hypothalamic area, amygdala and parabracial nucleus). In relating functional connectivity between cingulate-default-mode and cingulate-anxiety structures across Days 2-8, a significant inverse relationship (r = −0.65, p = 0.0004) was observed between these two functional interactions such that increased cingulate-DMN connectivity corresponded to decreased cingulate anxiety network connectivity. This investigation demonstrates that the cingulate is an important component of both the rodent DMN-like and anxiety networks
BMI Development of Normal Weight and Overweight Children in the PIAMA Study
Background: There is evidence that rapid weight gain during the first year of life is associated with overweight later in life. However, results from studies exploring other critical periods for the development of overweight are inconsistent. Objective: The objective was to investigate BMI development to assess at what ages essential differences between normal weight and overweight children occur, and to assess which age intervals the most strongly influence the risk of overweight at 8 years of age. Methods: Longitudinal weight and height data
The development of socio-economic health differences in childhood: results of the Dutch longitudinal PIAMA birth cohort
Background: People with higher socio-economic status (SES) are generally in better health. Less is known about when these socio-economic health differences set in during childhood and how they develop over time. The goal of this study was to prospectively study the development of socio-economic health differences in the Netherlands, and to investigate possible explanations for socio-economic variation in childhood health. Methods: Data from the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study were used for the analyses. The PIAMA study followed 3,963 Dutch children during their first eight years of life. Common childhood health problems (i.e. eczema, asthma symptoms, general health, frequent respiratory infections, overweight, and obesity) were assessed annually using questionnaires. Maternal educational level was used to indicate SES. Possible explanatory lifestyle determinants (breastfeeding, smoking during pregnancy, smoking during the first three months, and day-care centre attendance) and biological determinants (maternal age at birth, birthweight, and older siblings) were analysed using generalized estimating equations. Results: This study shows that socio-economic differences in a broad range of health problems are already present early in life, and persist during childhood. Children from families with low socio-economic backgrounds experience more asthma symptoms (odds ratio (OR) 1.27; 95% Confidence Interval (CI) 1.08-1.49), poorer general health (OR 1.36; 95% CI 1.16-1.60), more frequent respiratory infections (OR 1.57; 95% CI 1.35-1.83), more overweight (OR 1.42; 95% CI 1.16-1.73), and more obesity (OR 2.82; 95% CI 1.80-4.41). The most important contributors to the observed childhood socio-economic health disparities are socio-economic differences in maternal age at birth, breastfeeding, and day-care centre attendance. Conclusions: Socio-economic health disparities already occur very early in life. Socio-economic disadvantage takes its toll on child health before birth, and continues to do so during childhood. Therefore, action to reduce health disparities needs to start very early in life, and should also address socio-economic differences in maternal age at birth, breastfeeding habits, and day-care centre attendance
A pipeline for high throughput detection and mapping of SNPs from EST databases
Single nucleotide polymorphisms (SNPs) represent the most abundant type of genetic variation that can be used as molecular markers. The SNPs that are hidden in sequence databases can be unlocked using bioinformatic tools. For efficient application of these SNPs, the sequence set should be error-free as much as possible, targeting single loci and suitable for the SNP scoring platform of choice. We have developed a pipeline to effectively mine SNPs from public EST databases with or without quality information using QualitySNP software, select reliable SNP and prepare the loci for analysis on the Illumina GoldenGate genotyping platform. The applicability of the pipeline was demonstrated using publicly available potato EST data, genotyping individuals from two diploid mapping populations and subsequently mapping the SNP markers (putative genes) in both populations. Over 7000 reliable SNPs were identified that met the criteria for genotyping on the GoldenGate platform. Of the 384 SNPs on the SNP array approximately 12% dropped out. For the two potato mapping populations 165 and 185 SNPs segregating SNP loci could be mapped on the respective genetic maps, illustrating the effectiveness of our pipeline for SNP selection and validation
Factors and processes shaping the population structure and distribution of genetic variation across the species range of the freshwater snail radix balthica (Pulmonata, Basommatophora)
Background: Factors and processes shaping the population structure and spatial distribution of genetic diversity across a species' distribution range are important in determining the range limits. We comprehensively analysed the influence of recurrent and historic factors and processes on the population genetic structure, mating system and the distribution of genetic variability of the pulmonate freshwater snail Radix balthica. This analysis was based on microsatellite variation and mitochondrial haplotypes using Generalised Linear Statistical Modelling in a Model Selection framework. Results: Populations of R. balthica were found throughout North-Western Europe with range margins marked either by dispersal barriers or the presence of other Radix taxa. Overall, the population structure was characterised by distance independent passive dispersal mainly along a Southwest-Northeast axis, the absence of isolation-by-distance together with rather isolated and genetically depauperated populations compared to the variation present in the entire species due to strong local drift. A recent, climate driven range expansion explained most of the variance in genetic variation, reducing at least temporarily the genetic variability in this area. Other factors such as geographic marginality and dispersal barriers play only a minor role. Conclusions: To our knowledge, such a population structure has rarely been reported before. It might nevertheless be typical for passively dispersed, patchily distributed taxa (e.g. freshwater invertebrates). The strong local drift implied in such a structure is expected to erode genetic variation at both neutral and coding loci and thus probably diminish evolutionary potential. This study shows that the analysis of multiple factors is crucial for the inference of the processes shaping the distribution of genetic variation throughout species ranges. Additional files Additional file 1: Distribution of Radix taxa. Spatial distribution of the Radix MOTU as defined in Pfenninger et al. 2006 plus an additional, newly discovered taxon. This map is the basis for the inference of the species range of R. balthica. Additional file 2: Sampling site table and spatial distribution of diversity indices, selfing estimates and inferred population bottlenecks for R. balthica. Table of sampling site code, geographical position in decimal degrees latitude and longitude, number of individuals analysed with microsatellites (Nnuc), expected heterozygosity (HE) and standard deviation across loci, mean rarefied number of alleles per microsatellite locus (A) and their standard deviation, number of individuals analysed for mitochondrial variation (Nmt), rarefied number of mitochondrial COI haplotypes (Hmt), number of individuals measured for body size (Nsize). Figures A1 - A3 show a graphical representation of the spatial distribution of He, Hmt and, s, respectively. Additional file 3: Assessment of environmental marginality. PCA (principle component analysis) on 35 climatic parameters for the period from 1960 - 2000 from publicly availableWorldClim data. Additional file 4: Inference of a recent climate driven range expansion in R. balthica. Analysis of the freshwater benthos long term monitoring data of the Swedish national monitoring databases at the Swedish University of Agricultural Sciences SLU with canonical correspondence analysis
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