Lead exposure and biological effects in pied flycatchers (Ficedula hypoleuca) before and after the closure of a lead mine in northern Sweden

Mining activities affect the surrounding environment by increasing exposure to metals. In this study, metal accumulation and its effects on reproduction and health of pied flycatcher (Ficedula hypoleuca) nestlings were monitored before and up to five years after a lead mine and enrichment plant closed down. The lead concentration in moss, nestling blood, liver and feces all indicated decreased lead exposure by at least 31% after closure, although only blood lead decreased significantly. Although the birds responded fairly well to the changed atmospheric deposition (based on moss samples), concentrations were still higher compared with birds in a reference area, and breeding was affected at the mine (smaller clutches and higher mortality). Surviving nestlings suffered from lower hemoglobin levels, mean cell hemoglobin concentrations and inhibited delta-aminolevulinic acid dehydratase activity. Lead poisoning contributed to poor health and adverse reproductive effects, but other factors (e.g. increased parasitic load) probably also affected the birds.

Formation of bile acids in man: conversion of cholesterol into 5-beta-cholestane-3-alpha, 7-alpha, 12-alpha-triol in liver homogenates

The mechanisms of the conversion of cholesterol into bile acids in man were studied by examining the metabolism of cholesterol-1,2-(3)H, cholest-5-ene-3beta,7alpha-diol-7beta-(3)H, tritiumlabeled 7alpha-hydroxycholest-4-en-3-one, 7alpha,12alpha-dihydroxycholest-4-en-3-one, and cholest-5-ene-3beta,7alpha,12alpha-triol in fractions of liver homogenates. The 20,000 g supernatant fluid catalyzed the conversion of cholesterol into cholest-5-ene-3beta,7alpha-diol, 7alpha-hydroxycholest-4-en-3-one, 7alpha-12alpha-dihydroxycholest-4-en-3-one, and 5beta-cholestane-3alpha,7alpha,12alpha-triol. In the presence of microsomal fraction fortified with NAD(+), cholest-5-ene-3beta,7alpha-diol was converted into 7alpha-hydroxycholest-4-en-3-one, and when this fraction was fortified with NADPH small amounts of cholest-5-ene-3beta-7alpha,12alpha-triol were formed. 7alpha-Hydroxycholest-4-en-3-one was metabolized into 7alpha-12alpha-dihydroxycholest-4-en-3-one in the presence of microsomal fraction fortified with NADPH and into 5beta-cholestane-3alpha,7alpha-diol in the presence of 100,000 g supernatant fluid. Cholest-5-ene-3beta,7alpha,12alpha-triol was converted into 7alpha,12alpha-dihydroxycholest-4-en-3-one in the presence of microsomal fraction fortified with NAD(+). The 100,000 g supernatant fluid catalyzed the conversion of 7alpha,12alpha-dihydroxycholest-4-en-3-one into 5beta-cholestane-3alpha,7alpha,12alpha-triol. The sequence of reactions in the conversion of cholesterol into 5beta-cholestane-3alpha,7alpha-diol and 5beta-cholestane-3alpha,7alpha,12alpha-triol, the subcellular localization of the enzymes, and the cofactor requirements were found to be the same as those described for rat liver.

Updated stomatal flux and flux-effect models for wheat for quantifying effects of ozone on grain yield, grain mass and protein yield

Field measurements and open-top chamber experiments using nine current European winter wheat cultivars provided a data set that was used to revise and improve the parameterisation of a stomatal conductance model for wheat, including a revised value for maximum stomatal conductance and new functions for phenology and soil moisture. For the calculation of stomatal conductance for ozone a diffusivity ratio between O(3) and H(2)O in air of 0.663 was applied, based on a critical review of the literature. By applying the improved parameterisation for stomatal conductance, new flux-effect relationships for grain yield, grain mass and protein yield were developed for use in ozone risk assessments including effects on food security. An example of application of the flux model at the local scale in Germany shows that negative effects of ozone on wheat grain yield were likely each year and on protein yield in most years since the mid 1980s.

Limitations of a pencil beam approach to photon dose calculations in the head and neck region

The inherent limitations of a specific pencil beam model have been studied when applied to a cylindrical geometry simulating the neck region. A comparison is made between measured and calculated absorbed dose in a cylindrical phantom. The goal is to quantify the deviations in the absorbed dose level, i.e., the dose per monitor unit, when photons are used for the treatment of head and neck tumours. Square fields ranging from 5 x 5 up to 30 x 30 cm2 are studied for photon beam energies of 60Co, 4, 6 and 18 MV. Ionisation chamber measurements have been performed in the cylinder as well as in two other configurations in order to trace the origin of possible deviations. For 18 MV no significant deviations are found between measurement and calculation in the cylindrical configuration. For the lower energies, an overestimation of the calculated dose in the cylindrical configuration up to about 6% for a 20 x 20-cm2 60Co field has been found. These deviations have been traced to the basic approximation for the integration volume for phantom scatter calculations inherent in this pencil beam implementation.

A meta-analysis of the executive function components inhibition, shifting, and attention in intellectual disabilities

BACKGROUND

Executive function is a concept for higher-order cognitive functions, which have the role of controller and modulator of cognitive abilities. The consensus in the literature is that people with an intellectual disability perform significantly lower on executive function tasks than groups matched on chronological age. The comparison with groups matched on mental age is less clear. Therefore, the objective of this meta-analysis was to investigate to what extent executive function is impaired in people with intellectual disability compared with a typically developing control group matched on mental age. It was also investigated if the executive function component and intellectual disability aetiology moderated the effect.

METHODS

Eligibility criteria were participants with intellectual disability (IQ ≤ 75) without a dual diagnosis; a comparison group matched on mental age; executive function outcome reported in a group comparison study design with n ≥ 10. Working memory tasks and ratings of executive function were not included. The literature search yielded 6637 potentially interesting articles. Twenty-six studies (with 99 effect sizes) including 1395 participants were included in the quantitative synthesis.

RESULTS

A multilevel random-effects meta-analysis found that people with intellectual disability performed statistically significantly lower than the mental age-matched group on the executive function tasks, g = -0.34, 95% confidence interval = [-0.53, -0.16]. However, the heterogeneity between effect sizes was large. The intellectual disability aetiology moderator was significant, but it only reduced the heterogeneity marginally.

CONCLUSION

The overall conclusion is that individuals with an intellectual disability have more problems with executive function tasks than mental age-matched controls. Limitations are the large unexplained variance and the remarkably high number (69) of different tests that were used, which make more detailed conclusions problematic. This meta-analysis implies that future studies need to be of better quality, to have higher power, and to a higher degree use the same executive function tests.