Evaluation of Grip Force Using Electromyograms in Isometric Isotonic Conditions

The purpose of this study was to develop a relationship to evaluate the grip force (force_rel) using the electromyogram (EMG_rel) of the flexor digitorum superficialis (FDS) and of the extensor digitorum (ED) according to the flexion-extension wrist angle (θ_f.e) and to the pronation-supination forearm angle (θ_p-s).

Fifteen participants had to exert 3 levels of grip forces in 4 positions of the wrist combined with 3 positions of the forearm.

The relationship is:

force_rel = 0.0045· θ_f-e· EMG_rel(FDS) + 0.48· EMG_rel(FDS)–0.0014 · θ_f-e · EMG_rel(ED) –0.0016 · θ_p.s · EMG_rel(ED) + 0.4· EMG_rel(ED)

This relationship can be used to estimate grip force for levels of strength lower than 50% of the maximal voluntary contraction.     

EuroBionet: a pan-European biomonitoring network for urban air quality assessment

EuroBionet, the 'European Network for the Assessment of Air Quality by the Use of Bioindicator Plants', is an EU-funded cooperative project currently consisting of public authorities and scientific institutes from 12 cities in 8 countries. In 2000, the bioindicator plants tobacco (Nicotiana tabacum Bel W3), poplar (Populus nigra 'Brandaris'), spiderwort (Tradescantia sp. clone 4430), Italian rye grass (Lolium multiflorum italicum) and curly kale (Brassica oleracea acephala) were exposed to ambient air at 90 monitoring sites according to standardised methods. Visible injuries and growth parameters were assessed and the accumulation of toxic substances in leaves determined. The exposure of tobacco resulted in a gradient with low levels of ozone-induced foliar injury in N and NW Europe, and medium to high values in the southern and central regions. The results of heavy metal and sulphur analyses in rye grass samples generally showed low to very low sulphur and low to medium heavy metal concentrations in leaves. In some cities, however, local hot spots of heavy metal contamination were detected. Analyses of the PAH contents in curly kale leaves gave low to medium values, with locally elevated levels at traffic-exposed sites.     

Tissue distribution and bioconcentration factors of PCDD/Fs in the liver and adipose tissue following chronic ingestion of contaminated milk in rats

The aim of this study was to determine the tissue distribution of 17 PCDD/Fs following the chronic ingestion of contaminated milk in rats and to assess the "target tissue/milk" BioConcentration Factors (BCFs) of these molecules. Contaminated milk, collected in a polluted area, has been incorporated into the diet of male rats at a low dose (31 pg I-TEQ/day/rat). For this exposure, the accumulation of PCDD/Fs in target tissues (liver and adipose tissue) was limited, the tissue concentrations stabilising between 90 and 120 days of daily intake to levels close to 3 pg/g of tissue (all tissues and molecules combined). The tissue distribution seemed to be governed by the congeners properties and by the tissue characteristics. An increase in the chlorination degree of dioxins caused a decrease in their incorporation in the adipose tissue, and consequently of the BCF values. Moreover, the distribution of dioxins between hepatocytes and adipocytes differed: unlike the liver, the quantities of dioxins in the adipose tissue were significantly (P<0.05) correlated to the quantity of tissue fat. Only in the liver, the incorporation of PCDDs seemed to be facilitated when the chlorination degree of these congeners increased, the reverse phenomenon having been observed for PCDFs. However, for the same level of chlorination, the BCFs of PCDFs were 2.4 times higher than those of PCDDs in this tissue. The absence of correlation between the quantity of dioxins and that of fat and the BCFs differences of theses congeners suggested that dioxins fixation process in the liver was selective.     

Reactivity of secondary phases in weathered limestone using isotopic tracers (D and 18O)

Environmental Science and Pollution Research - For a long time, limestone has been massively used in stone building and monuments because of its easy extraction and common presence in the...     

Expression of copper-resistance genes in microbial communities under copper stress and oxic/anoxic conditions

Microorganisms have developed copper-resistance mechanisms in order to survive in contaminated environments. The abundance and expression of the copper-resistance genes cusA and copA, encoding respectively for a Resistance Cell Nodulation protein and for a P-type ATP-ase pump, was assessed along a gradient of copper concentration in microcosms prepared from Seine estuary mudflat sediment. We demonstrated that the abundance of copA and cusA genes decreased with the increase of copper concentration and that cusA gene was up to ten times higher than the copA gene. Only the copA gene was expressed in both oxic and anoxic conditions. The abundance and activity of the microbial community remained constant whatever the concentrations of copper along the gradient. The molecular phylogeny of the two copper-resistance genes was studied and revealed that the increase of copper increased the diversity of copA and cusA gene sequences.     

Carbon emission associated with respiration and calcification of nine gastropod species from the intertidal rocky shore of Western Europe

Intertidal rocky shores are characterized by vertical zonation that results from the interplay between environmental conditions, organism physiology, and species interactions. Metabolism of intertidal organisms is highly variable between species and it changes with vertical position along the intertidal gradient. The present study aimed to quantify the carbon metabolism of nine intertidal rocky shore gastropods, in order to clarify their respective roles in carbon production during emersion and immersion. The influences of monthly temperature variation and tidal level were tested for each species. Analyses were performed in the laboratory using the infrared gas analyzer method for measuring aerial respiration rates, and the dissolved inorganic carbon and total alkalinity technique for measuring aquatic respiration rate and calcification. Hourly carbon fluxes were calculated for the mean annual temperature of 13 °C measured in both air and underwater in the study area. Respiration rates were similar for emersion (8–25 μmol CO₂ g AFDW^?1 h^?1) and immersion (10–23 μmol DIC g AFDW^?1 h^?1). For all species, underwater respiration fluxes were more influenced by monthly temperature variation than by air fluxes, probably as an adaptation to the rapid changes occurring during emersion. Calcification was an important factor influencing annual carbon fluxes for all studied species; every species showed different calcification rates according to its size and position on the intertidal zone. Annual carbon emissions were calculated using the mean immersion/emersion time of each species. Intertidal gastropod carbon emission was primarily influenced by body biomass and their vertical position within the intertidal zone.     

A model for estimating the potential biomagnification of chemicals in a generic food web: Preliminary development

GOAL, SCOPE AND BACKGROUND: Bioaccumulation and biomagnification of organic pollutants have been increasingly assessed and modeled during the last years. Due to the complexity of these processes and the large variability of food webs, setting generic assessments for these parameters is really difficult. Equilibrium models, based on a compound's lipophylicity, are the main tool in regulatory proposals, such as for identifying Persistent, Bioaccumulative and Toxic Substances (PBTs), although a refinement has been claimed by the scientific community. Toxicokinetic studies offer an alternative for these estimations, where biomagnification is modeled as a succession of bioaccumulation processes, each one regulated by toxicokinetic parameters. METHODS: A review of kinetic models covering species belonging to different trophic levels and with different ecological behavior has been conducted. The results were employed for setting a conceptual model for estimating the biomagnification potential in a generic food web, which was mathematically implemented through system dynamic models developed under data sheet software. Crystal Ball was then employed for allowing Monte Carlo based probabilistic calculations. Bioaccumulation laboratory assays have been performed to estimate toxicokinetic parameters in mussels (Mytilus edulis) with two PAHs (chrysene and benzo[a]pyrene). The contamination was delivered via food. The exposure period lasted more than one month followed then by a depuration phase. The contaminant content was determined on an individual basis on five replicates. RESULTS AND DISCUSSION:. The reviewed information suggested the development of a tiered conceptual biomagnification model, starting with a simplified food chain which can be refined to more realistic and complex models in successive levels. CONCLUSIONS: The mathematical implementation of the conceptual model offers tools for estimating the potential for bioaccumulation and biomagnification of chemicals under very different conditions. The versatility of the model can be used for both comparative estimations and for validating the model. RECOMMENDATIONS AND PERSPECTIVES: Since bioaccumulation and biomagnification processes are crucial elements for a proper risk assessment of chemicals, their estimation by mathematical models has been widely tested. However, inregulatory assessments, too simplistic models are still being used quite often. The biomagnification model presented in this study should be amore accurate alternative to these models. In comparison to other previously published biomagnification models, the present one covers the time variation of bioaccumulation using just a few toxicokinetic parameters.     

X-ray absorption and photoelectron spectroscopy investigation of selenite reduction by Fe-bearing minerals

The long-lived radionuclide ⁷⁹Se is one of the elements of concern for the safe storage of high-level nuclear waste, since clay minerals in engineered barriers and natural aquifer sediments strongly adsorb cationic species, but to lesser extent anions like selenate (Se^VIO₄²⁻) and selenite (Se^IVO₃²⁻). Previous investigations have demonstrated, however, that Se^IV and Se^VI are reduced by surface-associated Fe^II, thereby forming insoluble Se⁰ and Fe selenides. Here we show that the mixed Fe^II/^III (hydr)oxides green rust and magnetite, and the Fe^II sulfide mackinawite reduce selenite rapidly (< 1 day) to FeSe, while the slightly slower reduction by the Fe^II carbonate siderite produces elemental Se. In the case of mackinawite, both S^−II and Fe^II surface atoms are oxidized at a ratio of one to four by producing a defective mackinawite surface. Comparison of these spectroscopic results with thermodynamic equilibrium modeling provides evidence that the nature of reduction end product in these Fe^II systems is controlled by the concentration of HSe⁻; Se⁰ forms only at lower HSe⁻ concentrations related to slower HSeO₃⁻ reduction kinetics. Even under thermodynamically unstable conditions, the initially formed Se solid phases may remain stable for longer periods since their low solubility prevents the dissolution required for a phase transformation into more stable solids. The reduction by Fe²⁺-montmorillonite is generally much slower and restricted to a pH range, where selenite is adsorbed (pH < 7), stressing the importance of a heterogeneous, surface-enhanced electron transfer reaction. Although the solids precipitated by the redox reaction are nanocrystalline, their solubility remains below 6.3 × 10^− 8 M. No evidence for aqueous metal selenide colloids nor for Se sorption to colloidal phases was found. Since Fe^II phases like the ones investigated here should be ubiquitous in the near field of nuclear waste disposals as well as in the surrounding aquifers, mobility of the fission product ⁷⁹Se may be much lower than previously assumed.     

Meckel-Gruber syndrome: Prenatal diagnosis at 10 menstrual weeks using embryoscopy

A case of Meckel—Gruber syndrome was diagnosed by embryoscopy at 10 menstrual weeks, allowing for early termination of pregnancy. Post-mortem examination confirmed the presence of polydactyly and bilateral cystic lesions of the mesonephros and metanephros. Both the forming nephrons and the collecting ducts were involved in the formation of renal cysts.