Effect of selective recording on estimates of heritability

En este trabajo se analiza el efecto de la selección de datos sobre las estimaciones de heredabilidad. Se estimó el valor de heredabilidad del tamaño de camada en una población porcina en la que los datos correspondientes a las cerdas más viejas eran una muestra seleccionada. Las estimaciones se obtuvieron usando distintos conjuntos de datos derivados de toda la información disponible. Esos conjunto de datos se compararon evaluando su capacidad predictiva. Se vio que las estimaciones de heredabilidad obtenidas utilizando todos los datos disponibles correspondían a valores infraestimados. También se simuló un carácter materno y se generó un conjunto de datos seleccionados eliminando aquellos correspondientes a las hembras sin padres conocidos. Distintos modelos, habitualmente empleados cuando no existe selección de registros, se consideraron para estimar el valor de heredabilidad. Los resultados mostraron que ninguno de esos modelos ofrecía estimaciones insesgadas. Sólo los modelos que tenían en cuenta el efecto de la selección sobre la media residual y la media y varianza genéticas ofrecían estimaciones poco sesgadas. Sin embargo, para poder aplicarlos se debe conocer la selección realizada. El problema de la selección de datos es difícil de abordar cuando se desconoce cual es el proceso de selección que se ha realizado en una población.

Conditional equilibrium constants in multicomponent heterogeneous adsorption: The conditional affinity spectrum

The concept of conditional stability constant is extended to the competitive binding of small molecules to heterogeneous surfaces or macromolecules via the introduction of the conditional affinity spectrum (CAS). The CAS describes the distribution of effective binding energies experienced by one complexing agent at a fixed concentration of the rest. We show that, when the multicomponent system can be described in terms of an underlying affinity spectrum [integral equation (IE) approach], the system can always be characterized by means of a CAS. The thermodynamic properties of the CAS and its dependence on the concentration of the rest of components are discussed. In the context of metal/proton competition, analytical expressions for the mean (conditional average affinity) and the variance (conditional heterogeneity) of the CAS as functions of pH are reported and their physical interpretation discussed. Furthermore, we show that the dependence of the CAS variance on pH allows for the analytical determination of the correlation coefficient between the binding energies of the metal and the proton. Nonideal competitive adsorption isotherm and Frumkin isotherms are used to illustrate the results of this work. Finally, the possibility of using CAS when the IE approach does not apply (for instance, when multidentate binding is present) is explored. © 2006 American Institute of Physics.

How do gastroenterologists assess overall activity of eosinophilic esophagitis in adult patients?

OBJECTIVES: There is no "gold standard" for assessing disease activity in patients with eosinophilic esophagitis (EoE). We aimed to compare physicians' judgment of EoE activity with patients' judgment of symptom severity. We also aimed to examine the relative contribution of symptoms as well as endoscopic and histologic findings in shaping physicians' judgment of EoE activity. METHODS: Six gastroenterologists (all EoE experts) assessed EoE-associated symptoms in adult patients. Patients completed a symptom instrument and provided global assessment of EoE symptom severity (PatGA) (Likert scale: 0 (inactive) to 10 (most active)). Following esophagogastroduodenoscopy with biopsy sampling, gastroenterologists provided a global assessment of EoE activity (PhysGA) (Likert scale from 0 to 10) based on patient history and endoscopic and histologic findings. Linear regression and analysis of variance was used to quantify the extent to which variations in severity of EoE symptoms and endoscopic and histologic findings explain variations in PhysGA. RESULTS: A total of 149 EoE patients were prospectively included (71.8% male, median age at inclusion 38 years, 71.8% with concomitant allergies). A moderate positive correlation between PhysGA and PatGA (rho=0.442, P<0.001) was observed and the mean difference in the Bland-Altman plot was 1.77. Variations in severity of endoscopic findings, symptoms, and histologic findings alone explained 53%, 49%, and 30%, of the variability in PhysGA, respectively. Together, these findings explained 75% of variability in PhysGA. CONCLUSIONS: Gastroenterologists rate EoE activity mainly on the basis of endoscopic findings and symptoms and, to a lesser extent, on histologic findings.

Evaluation of substrates on the emergence of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) Seedlings

Choosing a substrate is the determinant factor for the seedling producer; thus, the aim of this study was to evaluate the effect of different types of substrates on the emergence of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) seedlings. The experiment was carried out in a greenhouse and the experimental design was in randomized blocks, with three treatments and five replicates of 72 seeds per plot. The treatments consisted of the following substrates: coconut fiber, vermiculite and Plantmax® Citrus. The number of emerged seedlings was weekly counted for 105 days. Data regarding seedling height were obtained, and the emergence velocity index and mean time, besides total emergence percentage and that over time were calculated. Results from total mean emergence percentage, seedling height, emergence velocity index (EVI), and mean emergence time (MET) were subjected to analysis of variance and means were compared by the Tukey's test at 5% significance. The curves concerning the emergence percentage over time were fit by the logistic growth equation for each treatment and the means of each parameter (A, B, C) were compared by the Duncan's test at 5% significance. The substrates vermiculite led to the highest values of emergence percentage differing from the PlantMax® Citrus, but not of the coconut fiber, however the vermiculite promoted seedling height in a shorter time; therefore, this substrate is recommended for the initial development of "araticum-de-terra-fria" (Annona emarginata (Schltdl.) H. Rainer) seedlings.

Spatiotemporal variability in radial growth of trees in the Central Pyrenees: climatic and site influences.

To understand how tree growth has responded to recent climate warming, an understanding of the tree-climate-site complex is necessary. To achieve this, radial growth variability among 204 trees established before 1850 was studied in relation to both climatic and site factors. Seventeen forest stands were sampled in the Spanish Central Pyrenees. Three species were studied: Pinus uncinata, Abies alba, and Pinus sylvestris. For each tree, a ring-width residual chronology was built. All trees cross-dated well, indicating a common influence of the regional climate. For the 1952-1993 period, the radial growth of all species, especially P. uncinata, was positively correlated with warm Novembers during the year before ring formation and warm Mays of the year the annual ring formed. Differences in species-stand elevation modulated the growth-climate associations. Radial growth in P. uncinata at high elevation sites was reduced when May temperatures were colder and May precipitation more abundant. In the 20th century, two contrasting periods in radial growth were observed: one (1900-1949) with low frequency of narrow and wide rings, low mean annual sensitivity, and low common growth variation; and another (1950-1994) with the reverse characteristics. The increased variability in radial growth since the 1950s was observed for all species and sites, which suggests a climatic cause. The low shared variance among tree chronologies during the first half of the 20th century may result from a"relaxation" of the elevation gradient, allowing local site conditions to dominate macroclimatic influence. These temporal trends may be related to the recently reported increase of climatic variability and warmer conditions. This study emphasizes the need to carefully assess the relationships between radial growth and site conditions along ecological gradients to improve dendroclimatic reconstructions.

Giant monopole energies from a constrained relativistic mean-field approach

Background:Average energies of nuclear collective modes may be efficiently and accurately computed using a nonrelativistic constrained approach without reliance on a random phase approximation (RPA). Purpose: To extend the constrained approach to the relativistic domain and to establish its impact on the calibration of energy density functionals. Methods: Relativistic RPA calculations of the giant monopole resonance (GMR) are compared against the predictions of the corresponding constrained approach using two accurately calibrated energy density functionals. Results: We find excellent agreement at the 2% level or better between the predictions of the relativistic RPA and the corresponding constrained approach for magic (or semimagic) nuclei ranging from 16 O to 208 Pb. Conclusions: An efficient and accurate method is proposed for incorporating nuclear collective excitations into the calibration of future energy density functionals.

Bystander responses to a violent incident in an immersive virtual environment

Under what conditions will a bystander intervene to try to stop a violent attack by one person on another? It is generally believed that the greater the size of the crowd of bystanders, the less the chance that any of them will intervene. A complementary model is that social identity is critical as an explanatory variable. For example, when the bystander shares common social identity with the victim the probability of intervention is enhanced, other things being equal. However, it is generally not possible to study such hypotheses experimentally for practical and ethical reasons. Here we show that an experiment that depicts a violent incident at life-size in immersive virtual reality lends support to the social identity explanation. 40 male supporters of Arsenal Football Club in England were recruited for a two-factor between-groups experiment: the victim was either an Arsenal supporter or not (in-group/out-group), and looked towards the participant for help or not during the confrontation. The response variables were the numbers of verbal and physical interventions by the participant during the violent argument. The number of physical interventions had a significantly greater mean in the ingroup condition compared to the out-group. The more that participants perceived that the Victim was looking to them for help the greater the number of interventions in the in-group but not in the out-group. These results are supported by standard statistical analysis of variance, with more detailed findings obtained by a symbolic regression procedure based on genetic programming. Verbal interventions made during their experience, and analysis of post-experiment interview data suggest that in-group members were more prone to confrontational intervention compared to the out-group who were more prone to make statements to try to diffuse the situation.

The use of beta-blockers is associated with the occurrence of acute kidney injury in severe alcoholic hepatitis.

BACKGROUND & AIMS: The beneficial effect of nonselective beta-blockers (NSBB) has recently been questioned in patients with end-stage cirrhosis. We analysed the impact of NSBB on outcomes in severe alcoholic hepatitis (AH). METHODS: This study was based on a prospective database of patients with severe, biopsy-proven AH. Patients admitted from July, 2006 to July, 2014 were retrospectively studied. Patients were divided into two groups (with and without NSBB) and assessed for the occurrence of Acute Kidney Injury (AKI) and transplant-free mortality during a 168-day follow-up period. RESULTS: One hundred thirty-nine patients were included, the mean Maddrey score was 71 ± 34 and 86 patients (61.9%) developed AKI. Forty-eight patients (34.5%) received NSBB. The overall 168-day transplant-free mortality was 50.5% (95%CI, 41.3-60.0%). The overall 168-day cumulative incidence of AKI was 61.9% (95%CI, 53.2-69.4%). When compared, patients with NSBB had a lower heart rate (65 ± 13 vs 92 ± 12, P < 0.0001) and a lower mean arterial pressure (MAP, 78 ± 3 vs 87 ± 5, P < 0.0001). Patients with NSBB had comparable MELD scores, Maddrey scores, and medical histories. The 168-day transplant-free mortality was 56.8% (95%CI, 41.3-69.7%) in patients with NSBB and 46.7% (95%CI, 35.0-57.6%) without NSBB (P = 0.25). The 168-day cumulative incidence of AKI was 89.6% (95%CI, 74.9-95.9%) with NSBB compared to 50.4% (95%CI: 39.0-60.7) for no NSBB (P = 0.0001). The independent factors predicting AKI were a higher MELD score and the presence of NSBB. CONCLUSIONS: The use of NSBB in patients with severe AH is independently associated with a higher cumulative incidence of AKI.

Estimating 750 years of temperature variations and uncertainties in the Pyrenees by tree-ring reconstructions and climate simulations.

Past temperature variations are usually inferred from proxy data or estimated using general circulation models. Comparisons between climate estimations derived from proxy records and from model simulations help to better understand mechanisms driving climate variations, and also offer the possibility to identify deficiencies in both approaches. This paper presents regional temperature reconstructions based on tree-ring maximum density series in the Pyrenees, and compares them with the output of global simulations for this region and with regional climate model simulations conducted for the target region. An ensemble of 24 reconstructions of May-to-September regional mean temperature was derived from 22 maximum density tree-ring site chronologies distributed over the larger Pyrenees area. Four different tree-ring series standardization procedures were applied, combining two detrending methods: 300-yr spline and the regional curve standardization (RCS). Additionally, different methodological variants for the regional chronology were generated by using three different aggregation methods. Calibration verification trials were performed in split periods and using two methods: regression and a simple variance matching. The resulting set of temperature reconstructions was compared with climate simulations performed with global (ECHO-G) and regional (MM5) climate models. The 24 variants of May-to-September temperature reconstructions reveal a generally coherent pattern of inter-annual to multi-centennial temperature variations in the Pyrenees region for the last 750 yr. However, some reconstructions display a marked positive trend for the entire length of the reconstruction, pointing out that the application of the RCS method to a suboptimal set of samples may lead to unreliable results. Climate model simulations agree with the tree-ring based reconstructions at multi-decadal time scales, suggesting solar variability and volcanism as the main factors controlling preindustrial mean temperature variations in the Pyrenees. Nevertheless, the comparison also highlights differences with the reconstructions, mainly in the amplitude of past temperature variations and in the 20th century trends. Neither proxy-based reconstructions nor model simulations are able to perfectly track the temperature variations of the instrumental record, suggesting that both approximations still need further improvements.

Assessment of Immature Platelet Fraction in the Diagnosis of Wiskott-Aldrich Syndrome.

Children with Wiskott-Aldrich syndrome (WAS) are often first diagnosed with immune thrombocytopenia (ITP), potentially leading to both inappropriate treatment and the delay of life-saving definitive therapy. WAS is traditionally differentiated from ITP based on the small size of WAS platelets. In practice, microthrombocytopenia is often not present or not appreciated in children with WAS. To develop an alternative method of differentiating WAS from ITP, we retrospectively reviewed all complete blood counts and measurements of immature platelet fraction (IPF) in 18 subjects with WAS and 38 subjects with a diagnosis of ITP treated at our hospital. Examination of peripheral blood smears revealed a wide range of platelet sizes in subjects with WAS. Mean platelet volume (MPV) was not reported in 26% of subjects, and subjects in whom MPV was not reported had lower platelet counts than did subjects in whom MPV was reported. Subjects with WAS had a lower IPF than would be expected for their level of thrombocytopenia, and the IPF in subjects with WAS was significantly lower than in subjects with a diagnosis of ITP. Using logistic regression, we developed and validated a rule based on platelet count and IPF that was more sensitive for the diagnosis of WAS than was the MPV, and was applicable regardless of the level of platelets or the availability of the MPV. Our observations demonstrate that MPV is often not available in severely thrombocytopenic subjects, which may hinder the diagnosis of WAS. In addition, subjects with WAS have a low IPF, which is consistent with the notion that a platelet production defect contributes to the thrombocytopenia of WAS. Knowledge of this detail of WAS pathophysiology allows to differentiate WAS from ITP with increased sensitivity, thereby allowing a physician to spare children with WAS from inappropriate treatment, and make definitive therapy available in a timely manner.

Neuro-mechanical determinants of repeated treadmill sprints - Usefulness of an "hypoxic to normoxic recovery" approach.

To improve our understanding of the limiting factors during repeated sprinting, we manipulated hypoxia severity during an initial set and examined the effects on performance and associated neuro-mechanical alterations during a subsequent set performed in normoxia. On separate days, 13 active males performed eight 5-s sprints (recovery = 25 s) on an instrumented treadmill in either normoxia near sea-level (SL; FiO2 = 20.9%), moderate (MH; FiO2 = 16.8%) or severe normobaric hypoxia (SH; FiO2 = 13.3%) followed, 6 min later, by four 5-s sprints (recovery = 25 s) in normoxia. Throughout the first set, along with distance covered [larger sprint decrement score in SH (-8.2%) compared to SL (-5.3%) and MH (-7.2%); P < 0.05], changes in contact time, step frequency and root mean square activity (surface electromyography) of the quadriceps (Rectus femoris muscle) in SH exceeded those in SL and MH (P < 0.05). During first sprint of the subsequent normoxic set, the distance covered (99.6, 96.4, and 98.3% of sprint 1 in SL, MH, and SH, respectively), the main kinetic (mean vertical, horizontal, and resultant forces) and kinematic (contact time and step frequency) variables as well as surface electromyogram of quadriceps and plantar flexor muscles were fully recovered, with no significant difference between conditions. Despite differing hypoxic severity levels during sprints 1-8, performance and neuro-mechanical patterns did not differ during the four sprints of the second set performed in normoxia. In summary, under the circumstances of this study (participant background, exercise-to-rest ratio, hypoxia exposure), sprint mechanical performance and neural alterations were largely influenced by the hypoxia severity in an initial set of repeated sprints. However, hypoxia had no residual effect during a subsequent set performed in normoxia. Hence, the recovery of performance and associated neuro-mechanical alterations was complete after resting for 6 min near sea level, with a similar fatigue pattern across conditions during subsequent repeated sprints in normoxia.

Salt, blood pressure and cardiovascular risk : what is the most adequate preventive strategy? A Swiss perspective

Among the various strategies to reduce the incidence of non-communicable diseases reduction of sodium intake in the general population has been recognized as one of the most cost-effective means because of its potential impact on the development of hypertension and cardiovascular diseases. Yet, this strategic health recommendation of the WHO and many other international organizations is far from being universally accepted. Indeed, there are still several unresolved scientific and epidemiological questions that maintain an ongoing debate. Thus what is the adequate low level of sodium intake to recommend to the general population and whether national strategies should be oriented to the overall population or only to higher risk fractions of the population such as salt-sensitive patients are still discussed. In this paper, we shall review the recent results of the literature regarding salt, blood pressure and cardiovascular risk and we present the recommendations recently proposed by a group of experts of Switzerland. The propositions of the participating medical societies are to encourage national health authorities to continue their discussion with the food industry in order to reduce the sodium intake of food products with a target of mean salt intake of 5-6 grams per day in the population. Moreover, all initiatives to increase the information on the effect of salt on health and on the salt content of food are supported.

Does phylogeographic structure relate to climatic niche divergence? A test using maritime pine (Pinus pinaster Ait.)

Aim To disentangle the effects of environmental and geographical processes driving phylogenetic distances among clades of maritime pine (Pinus pinaster). To assess the implications for conservation management of combining molecular information with species distribution models (SDMs; which predict species distribution based on known occurrence records and on environmental variables). Location Western Mediterranean Basin and European Atlantic coast. Methods We undertook two cluster analyses for eight genetically defined pine clades based on climatic niche and genetic similarities. We assessed niche similarity by means of a principal component analysis and Schoener's D metric. To calculate genetic similarity, we used the unweighted pair group method with arithmetic mean based on Nei's distance using 266 single nucleotide polymorphisms. We then assessed the contribution of environmental and geographical distances to phylogenetic distance by means of Mantel regression with variance partitioning. Finally, we compared the projection obtained from SDMs fitted from the species level (SDMsp) and composed from the eight clade-level models (SDMcm). Results Genetically and environmentally defined clusters were identical. Environmental and geographical distances explained 12.6% of the phylogenetic distance variation and, overall, geographical and environmental overlap among clades was low. Large differences were detected between SDMsp and SDMcm (57.75% of disagreement in the areas predicted as suitable). Main conclusions The genetic structure within the maritime pine subspecies complex is primarily a consequence of its demographic history, as seen by the high proportion of unexplained variation in phylogenetic distances. Nevertheless, our results highlight the contribution of local environmental adaptation in shaping the lower-order, phylogeographical distribution patterns and spatial genetic structure of maritime pine: (1) genetically and environmentally defined clusters are consistent, and (2) environment, rather than geography, explained a higher proportion of variation in phylogenetic distance. SDMs, key tools in conservation management, better characterize the fundamental niche of the species when they include molecular information.