Mobility and distribution of arsenic in contaminated mine soils and its effects on the microbial pool.

Three soils, coming from a former mining site and characterized by a different degree of pollution, were analysed in terms of Arsenic (As) content, using three different analytical approaches, and its distribution in various soil fractions. The effect of As on soil microbial biomass (size, respiration and microbial quotients) was also analysed. Total arsenic concentration between soil fractions was significantly different and ranged from 189 to 4357mgkg(-1), indicating a high level of pollution. Soil sequential fractioning showed that more than 60 percent of total As was bound to Fe-Al oxides, suggesting a minor availability and environmental risk regardless the total concentration of As in the sample. On the contrary, water soluble As fraction showed a significant difference among the three samples. The largest water soluble As concentration was found in the sample with intermediate total As amount. As far as microbial biomass is concerned, it was found that bioavailable As negatively impacted microbial metabolism in terms of basal and cumulative respiration, and microbial quotients, suggesting a strong selection within microbial pool.

Copper distribution and hydrolase activities in a contaminated soil amended with dolomitic limestone and compost.

Chemical fractionation of copper in bulk soil and its distribution in the particle-size fractions were analyzed in a Cu-contaminated soil (674 ± 122 µg Cu g(-1), up to 1900 µg Cu g(-1) in the clay fraction) sampled from a wood preservation site left untreated and subsequently treated with dolomitic limestone (DL, 0.2% w/w) and compost (CM, 5% w/w), singly and in combination (DL+CM). Soil enzymatic activities of leucine aminopeptidase, cellulase, N-acetyl-ß-glucosaminidase, arylsulfatase, ß-glucosidase, acetate esterase, butyric esterase, and acid phosphatase were determined. Chemical speciation showed that Cu was mostly present in the acid-soluble and reducible fractions in both untreated and treated soils, whereas treatments with DL and CM reduced the soluble and exchangeable Cu fractions, due to Cu precipitation and complexation, and increased Cu bound to soil organic matter. Analysis of the particle-size fractions showed that more than 80% of Cu was in the silt and clay fractions and that treatment with CM increased the concentration of Cu in the sand size fractions. Soil treatment with DL and CM, singly or in combination, increased hydrolase activities, mainly in the clay fraction, with the largest positive effects on N-acetyl-ß-glucosaminidase, leucine aminopeptidase, and ß-glucosidase activities. Overall, results confirm that (1) Cu in contaminated soils is mainly bound to the silt-clay fraction, (2) CM additions change its allocation in the particle-size fractions, and (3) treatments with DL and CM singly and in combination reduce Cu solubility and its inhibitory effects on soil enzyme activities.

ExpIR-RO: A Collaborative International Project for Experimenting Voluntary Incident Reporting In the Public Healthcare Sector in Romania.

BACKGROUND: Patient safety within healthcare systems is a central aspect of health policy in most developed countries. From April 2007 to May 2009, the pilot project ExpIR-RO tested a voluntary incident reporting system in a public hospital in Bucharest Romania, in collaboration with two Italian hospitals (in Genoa and Milan). METHODS: Data were collected anonymously through a form based on the Australian Incident Monitoring System. After appropriate training in reporting adverse events (AEs), staff in the participating Departments voluntarily completed the form. The study lasted 12 months in the Bucharest and Genoa hospitals and 3 months in the Milan hospital. Frequency distributions of replies and AE rates per 1,000 hospitalization days per month were assessed. RESULTS: Overall, 185 AEs were reported (58 in Bucharest, 75 in Genoa and 52 in Milan). The corresponding rates (per 1,000 hospitalization days per month) were 1 in Bucharest, 3 in Genoa and 15 in Milan. Most AEs were related to diagnostic (28%) and surgical (14%) procedures and patient falls (12%) in Bucharest; patient falls (32%), nursing care (20%) and diagnostic procedures (19%) in Genoa; and nursing care (25%), drug prescription/administration (21%) and diagnostic procedures (17%) in Milan. Seventy-three per cent of respondents in Bucharest informed the patient of the AE, versus 64% in Genoa and 43% in Milan. Conversely, 75% of respondents in Genoa entered AEs in medical records versus 53% in Bucharest and 36% in Milan. CONCLUSION: ExpIR-RO experience suggests that incident reporting could be introduced on a larger scale in Romania.

[Tetragametic chimerism: Case report]. / Chimérisme tétragamétique : à propos d'un cas.

We report the third case of spontaneous monochorionic dizygous pregnancy, discovered on foetal sex discordance. Blood group testing on the female twin revealed a hematopoietic chimera. The mechanism of monochorionic dizygous formation could be the fusion of two independent zygotes at a late morula stage. A single placental mass with vascular anastomosis then develops. Stem cells exchanged during early foetal life can thus lead to chimeras, in similar conditions to stem cell transfusion in adults. Immaturity of the foetal immune system allows cell graft in the other twin's marrow. Assisted reproductive procedures are believed to promote such pregnancies.

Surface modification for enhanced silanation of zirconia ceramics.

OBJECTIVE: The overall goal of this research was to develop a practical method to chemically modify the surface of high strength dental ceramics (i.e. zirconia) to facilitate viable, robust adhesive bonding using commercially available silanes and resin cements. METHODS: Investigation focused on a novel approach to surface functionalize zirconia with a Si(x)O(y) "seed" layer that would promote chemical bonding with traditional silanes. ProCAD and ZirCAD blocks were bonded to a dimensionally similar composite block using standard techniques designed for silica-containing materials (silane and resin cement). ZirCAD blocks were treated with SiCl4 by vapor deposition under two different conditions prior to bonding. Microtensile bars were prepared and subjected to tensile forces at a crosshead speed of 1 mm/min scanning electron microscopy was used to analyze fracture surfaces and determine failure mode; either composite cohesive failure (partial or complete cohesive failure within composite) or adhesive failure (partial or complete adhesive failure). RESULTS: Peak stress values were analyzed using single-factor ANOVA (p<0.05). Microtensile testing results revealed that zirconia with a surface treatment of 2.6 nm Si(x)O(y) thick "seed" layer was similar in strength to the porcelain group (control). Analysis of failure modes indicated the above groups displayed higher percentages of in-composite failures. Other groups tested had lower strength values and displayed adhesive failure characteristics. CONCLUSION: Mechanical data support that utilizing a gas-phase chloro-silane pretreatment to deposit ultra-thin silica-like seed layers can improve adhesion to zirconia using traditional silanation and bonding techniques. This technology could have clinical impact on how high strength dental materials are used today.

Evolution of soil organic matter changes using pyrolysis and metabolic indices: a comparison between organic and mineral fertilization.

The aim of this study was to evaluate chemical and biochemical changes of organic matter in fertilized (ammonium nitrate) and amended (vermicompost and manure) soils using pyrolysis and metabolic indices. The metabolic potential [dehydrogenase (DH-ase)/water soluble organic carbon (WSOC)], the metabolic quotient (qCO2) and the microbial quotient (Cmic:Corg) were calculated as indices of soil organic matter evolution. Pyrolysis-gas chromatography (Py-GC) was used to study structural changes in the organic matter. Carbon forms and microbial biomass have been measured by dichromate oxidation and fumigation-extraction methods, respectively. Dehydrogenase activity has been tested using INT (p-Iodonitrotetrazolium violet) as substrate. The results showed that organic amendment increased soil microbial biomass and its activity which were strictly related to pyrolytic mineralization and humification indices (N/O, B/E3). Mineral fertilization caused a greater alteration of native soil organic matter than the organic amendments, in that a high release of WSOC and relatively large amounts of aliphatic pyrolytic products, were observed. Therefore, the pyrolysis and metabolic indices provided similar and complementary information on soil organic matter changes after mineral and organic fertilization.

Labile substrates quality as the main driving force of microbial mineralization activity in a poplar plantation soil under elevated CO2 and nitrogen fertilization.

Soil carbon (C) long term storage is influenced by the balance among ecosystem net primary productivity (NPP), the rate of delivery of new organic matter to soil pools and the decomposition of soil organic matter (SOM). The increase of NPP under elevated CO(2) can result in a greater production and higher turnover of fine roots or root exudation and, in turn, in an increase of labile C belowground. The aim of this work was to detect if changes in labile C substrates influenced the organic C storage in soils, verifying (i) whether treatments with elevated CO(2) and N fertilization induced changes in the amount and quality of labile C pools and in microbial C immobilization and (ii) whether these changes provoked modifications in the microbial C mineralization activity, and therefore changes in soil C losses. The effect of elevated CO(2) was a significant increase in both seasons (June and October 2004), of all labile C fractions: microbial biomass C (MBC), K(2)SO(4) extractable C (ExC), and water soluble C (WSC). The C/N ratio of the microbial biomass and of the K(2)SO(4) extractable SOM presented a seasonal fluctuation showing higher values in June, whereas the elevated CO(2) increased significantly the C/N ratio of these fractions independent of the season and the N addition, indicating a lower quality of labile SOM. Microbial respiration was more than doubled in October compared to June, confirming that changes in substrate quality and nutrient availability, occurring in the plantation at the beginning and at the end of the vegetative period, influenced the microbial activity in the bulk soil. Furthermore, the microbial respiration response to N fertilization was dependent on the season, with an opposite effect between June and October. The kinetic parameters calculated according to the first-order equation C(m)=C(0)(1-e(-kt)) were unaffected by elevated CO(2) treatment, except C(0)k and MR(basal), that showed a significant reduction, ascribable to (i) a lower quality of labile pools, and (ii) a more efficient microbial biomass in the use of available substrates. The C surplus found in elevated CO(2) soils was indeed immobilized and used for microbial growth, thus excluding a priming effect mechanism of elevated CO(2) on SOM decomposition.

Net carbon storage in a poplar plantation (POPFACE) after three years of free-air CO2 enrichment.

A high-density plantation of three genotypes of Populus was exposed to an elevated concentration of carbon dioxide ([CO(2)]; 550 micromol mol(-1)) from planting through canopy closure using a free-air CO(2) enrichment (FACE) technique. The FACE treatment stimulated gross primary productivity by 22 and 11% in the second and third years, respectively. Partitioning of extra carbon (C) among C pools of different turnover rates is of critical interest; thus, we calculated net ecosystem productivity (NEP) to determine whether elevated atmospheric [CO(2)] will enhance net plantation C storage capacity. Free-air CO(2) enrichment increased net primary productivity (NPP) of all genotypes by 21% in the second year and by 26% in the third year, mainly because of an increase in the size of C pools with relatively slow turnover rates (i.e., wood). In all genotypes in the FACE treatment, more new soil C was added to the total soil C pool compared with the control treatment. However, more old soil C loss was observed in the FACE treatment compared with the control treatment, possibly due to a priming effect from newly incorporated root litter. FACE did not significantly increase NEP, probably as a result of this priming effect.

Eco-physiological characterization of soil bacterial populations in different states of growth.

The method based on characterization of microbial populations in terms of their growth rate in agar plates has been used for testing the prediction of the theory of r- and K-selection in a microbial community from a tropical soil. Conditions which could lead bacterial populations to grow exponentially or to enter into a stationary phase were obtained by growing soil microbial populations in a chemostat and in a chemostat with recycle, respectively. Significant differences in population distribution patterns were observed by comparing results from the two growth systems. When soil community was grown in a chemostat and subjected specifically to well-defined r- and K-conditions, stable associations of organisms with r- and K-type characteristics developed as a consequence of environmental pressure. In contrast, when cultivated in chemostat with recycle under the same r- and K-conditions imposed on chemostat cultures, distribution patterns of r- and K-selected populations appeared very little affected by changes in substrate availability.

Microtubule treadmilling in vitro investigated by fluorescence speckle and confocal microscopy.

Whether polarized treadmilling is an intrinsic property of microtubules assembled from pure tubulin has been controversial. We have tested this possibility by imaging the polymerization dynamics of individual microtubules in samples assembled to steady-state in vitro from porcine brain tubulin, using a 2% glycerol buffer to reduce dynamic instability. Fluorescence speckled microtubules were bound to the cover-glass surface by kinesin motors, and the assembly dynamics of plus and minus ends were recorded with a spinning-disk confocal fluorescence microscopy system. At steady-state assembly, 19% of the observed microtubules (n = 89) achieved treadmilling in a plus-to-minus direction, 34% in a minus-to-plus direction, 37% grew at both ends, and 10% just shortened. For the population of measured microtubules, the distribution of lengths remained unchanged while a 20% loss of original and 27% gain of new polymer occurred over the 20-min period of observation. The lack of polarity in the observed treadmilling indicates that stochastic differences in dynamic instability between plus and minus ends are responsible for polymer turnover at steady-state assembly, not unidirectional treadmilling. A Monte Carlo simulation of plus and minus end dynamics using measured dynamic instability parameters reproduces our experimental results and the amount of steady-state polymer turnover reported by previous biochemical assays.

Comparison of response to serotonin of radial artery grafts and internal mammary grafts to native coronary arteries and the effect of diltiazem.

We studied the response of radial artery (RA) or left internal mammary artery grafts to the intraluminal infusion of serotonin in 22 consecutive patients 1 year after the operation, subsequently evaluating the effect of diltiazem in 9 patients. Serotonin causes a significant vasoconstriction of the RA grafts, but not of the left internal mammary artery grafts, whereas oral diltiazem treatment does not prevent the effect of the higher dose of serotonin on RA grafts.

Involvement of polyamines in the inhibiting effect of injury caused by cutting on K(+) uptake through the plasma membrane.

The inhibition of K(+) uptake through the plasma membrane resulting from injury caused by cutting, or from application of polyamines (PAs), has been investigated in root segments of maize (Zea mays L.) and pea (Pisum sativum L.). It was found, for both treatments, that K(+) uptake recovered if the segments were washed for 2 h. The K(+) uptake inhibited by cutting and that inhibited by spermidine treatment were stimulated to the same extent by fusicoccin. In addition, there was a correlation between the extent of the recovery of K(+) uptake caused by washing and the distribution, along the root axis, of both PAs and the activities of enzymes responsible for PA degradation. In apical segments of maize, where the PA content and the activity of the degradative enzyme polyamine oxidase (EC 1.5.3.3) were higher than in the more distal segments, the recovery of K(+) uptake caused by washing was also higher. On the other hand, the opposite trend was observed in root segments of pea, where the PA content and the activity of the degradative enzyme diamine oxidase (EC 1.4.3.6) were higher in distal segments in which K(+) uptake was greatly stimulated by washing. The effect of the amine-oxidase inhibitor, aminoguanidine, indicates that the degradation products of PAs are involved in the mechanism of inhibition of K(+) uptake by PAs. The data also seem to indicate that PAs and their degradation products are responsible for the inhibition of K(+) uptake occurring as a result of injury sustained by cutting roots into segments.

Effect of Exogenous Putrescine, Spermidine, and Spermine on K Uptake and H Extrusion through Plasmamembrane in Maize Root Segments.

The action of exogenous polyamines (putrescine, spermidine, and spermine) on ;washing' and fusicoccin-stimulated K(+) uptake and H(+) extrusion through the plasmamembrane in maize (Zea mays L., hybrid line Plenus S 516) root apical segments was studied. The results showed that polyamines inhibit the washing-stimulated K(+) influx and H(+) extrusion without interfering with K(+) uptake and H(+) extrusion stimulated by fusicoccin. Spermidine appeared to be the most effective in inhibiting K(+) uptake and H(+) extrusion while putrescine showed a smaller inhibiting action with respect to the others. The analysis of kinetic constants indicated that the polyamines behave as competitive inhibitors with respect to K(+).

The mechanism of deuterium oxide-induced protein degradation in Lemna minor.

Transfer of Lemna minor fronds to culture medium containing 50% (v/v) deuterium oxide induces a large increase in the rate of protein breakdown, which is not due to an increase in the activity of acidic or neutral proteolytic enzymes or peptidases. Biochemical and ultrastructural evidence indicates that deuterium oxide affects the properties of certain membranes, particularly the tonoplast, and allows vacuolar proteolytic enzymes to pass into the cytoplasm and cause the increased protein breakdown.

The effect of deuterium oxide on protein turnover in Lemna minor.

Lemna minor fronds transferred to a sterile culture medium containing 50% (v/v) deuterium oxide ((2)H2O) rapidly undergo a loss of soluble protein with a corresponding increase in free amino acids. The loss of protein is due to two factors: (i) the inhibition of protein synthesis for 4 h followed by a slower rate of synthesis than normal, (ii) a rapid 9-10 fold increase in protein degradation. In plants grown for longer periods (3-6 days) in 50% (2)H2O medium, protein synthesis is inhibited by 20% and the rate constant of degradation is 2-3 times that measured in fronds growing in normal (H2O containing) complete medium. The initial loss of protein is not due to the breakdown of any specific protein fraction. Investigation of several enzymes indicates that all proteins are catabolised in response to (2)H2O treatment. The implications of these results with regard to the interpretation of density-labelling experiments are discussed.

The control of the production of lactate and ethanol by higher plants.

Factors controlling the production of ethanol and lactate have been examined using cell free extracts prepared from pea seeds (Pisum sativum var Alaska) and parsnip roots (Pastinaca sativa). The result suggest that under aerobic conditions pyruvate decarboxylase is inactive. With the onset of anaerobiosis glycolysis leads to an accumulation of lactate with a corresponding fall in pH. The fall in pH activates pyruvate decarboxylase and initiates competition between lactate dehydrogenase and pyruvate decarboxylase for pyruvate. The effect of pyruvate concentration on the partitioning has been analysed in terms of a modified Wegscheider rule and shows that the ratio lactate dehydrogenase activity/pyruvate decarboxylase activity bears an inverse relationship to the pyruvate concentration. The decrease in ratio which occurs when the pyruvate concentration rises is enhanced by the co-operativity which is exhibited by pyruvate decarboxylase. The pH optimum of lactate dehydrogenase is alkaline whilst the pH optimum of pyruvic decarboxylase is acid, thus the two enzymes function as a pH-stat. The possibility of excessive production of lactic acid is further controlled by the response of lactate dehydrogenase to ATP; the enzyme is inhibited by ATP and the inhibition increases as the pH decreases. It is suggested that this mechanism functions to protect the plant from excess production of acid.