IGMPlot: A program to identify, characterize, and quantify molecular interactions.

We describe the development and features of a program called IGMPlot, which is based on the independent gradient model (IGM) and its local descriptor δ g . The IGM approach analyzes the gradient of the electron density (ED) in a molecular system to identify regions of space where chemical interactions take place. IGMPlot is intended for use by both experimental scientists and theoretical chemists. It is standalone software written in C++, with versions available for multiple platforms. Some key features are: probing and quantifying interactions between two given molecular fragments, determining bond strength (IBSI), estimating the atomic contributions to an intermolecular interaction and preparing data to build 2D and 3D representations of interaction regions. The software has been updated to include new features: critical point analysis of the ED, assessing ED asymmetry of a given bond (PDA) and a new descriptor called q g designed to enhance the IGM- δ g analysis. The program can be found at: http://igmplot.univ-reims.fr.

A field-pilot for passive bioremediation of As-rich acid mine drainage.

A field-pilot bioreactor exploiting microbial iron (Fe) oxidation and subsequent arsenic (As) and Fe co-precipitation was monitored during 6 months for the passive treatment of As-rich acid mine drainage (AMD). It was implemented at the Carnoulès mining site (southern France) where AMD contained 790-1315 mg L-1 Fe(II) and 84-152 mg L-1 As, mainly as As(III) (78-83%). The bioreactor consisted in five shallow trays of 1.5 m2 in series, continuously fed with AMD by natural flow. We monitored the flow rate and the water physico-chemistry including redox Fe and As speciation. Hydraulic retention time (HRT) was calculated and the precipitates formed inside the bioreactor were characterized (mineralogy, Fe and As content, As redox state). Since As(III) oxidation improves As retention onto Fe minerals, bacteria with the capacity to oxidize As(III) were quantified through their marker gene aioA. Arsenic removal yields in the pilot ranged between 3% and 97% (average rate (1.8 ±â€¯0.8) ✕ 10-8 mol L-1 s-1), and were positively correlated to HRT and inlet water dissolved oxygen concentration. Fe removal yields did not exceed 11% (average rate (7 ±â€¯5) ✕ 10-8 mol L-1 s-1). In the first 32 days the precipitate contained tooeleite, a rare arsenite ferric sulfate mineral. Then, it evolved toward an amorphous ferric arsenate phase. The As/Fe molar ratio and As(V) to total As proportion increased from 0.29 to 0.86 and from ∼20% to 99%, respectively. The number of bacterial aioA gene copies increased ten-fold during the first 48 days and stabilized thereafter. These results and the monitoring of arsenic speciation in the inlet and the outlet water, provide evidences that As(III) oxidized in the pilot. The biotreatment system we designed proved to be suitable for high As DMA. The formation of sludge highly enriched into As(V) rather than As(III) is advantageous in the perspective of long term storage.

Experimental observation of spatially localized dynamo magnetic fields.

We report the first experimental observation of a spatially localized dynamo magnetic field, a common feature of astrophysical dynamos and convective dynamo simulations. When the two propellers of the von Kármán sodium experiment are driven at frequencies that differ by 15%, the mean magnetic field's energy measured close to the slower disk is nearly 10 times larger than the one close to the faster one. This strong localization of the magnetic field when a symmetry of the forcing is broken is in good agreement with a prediction based on the interaction between a dipolar and a quadrupolar magnetic mode.

Mandibular magnetic distractor: preclinical validation.

The feasibility of magnetic activation for mandibular distraction has been demonstrated previously. In this study, we developed a biocompatible device to evaluate the feasibility of distraction in cadaveric subjects and the functionality of the device in bench tests. To confirm, considering the dimension of the distractor, that the torque applied on the internal magnet would be sufficient to activate distraction osteogenesis we measured, for different distances, the transmitted torque between a magnet (internal and external). We evaluated the friction force of the device, and the resilience of the magnet to the sterilisation process. To confirm the feasibility of distraction with this device, we proceeded to cadaveric tests, and evaluated the satisfaction of four surgeons. The force applied to the moving plate was greater than 50 Newtons (N) with a friction coefficient of η=0.2. We determined a friction torque of 65.10-3 N.mm in the distractor mechanism and demonstrated that sterilisation did not alter the magnet. Mandibular distraction had been successfully achieved in cadaveric trials, and surgeons were satisfied. This new device could be implanted in human subjects, for clinical assay, after approval by the regulatory agencies. The use of this fully internalised device should improve patients' comfort.

Sagittal split ramus osteotomy-related biomechanical properties.

Sagittal split ramus osteotomy (SSRO) is one of the most common maxillofacial operations, and the technique relies on a directed fracture involving different biomechanical variables. The aim of this study was to find out the biomechanical characteristics involved during each step of sagittal split osteotomy. We sampled eight fully dentate human mandibles and used the right side for hardness tests and the left side for a traction-to-fracture test within an unfinished SSRO. Right sides were sampled in five parts underlying the corticotomy course and tested with a hardness testing automatic machine. The mean hardness measures ranked to 21.5HV (Hardness Vickers Unit): 17.8HV; 27.4HV; 22.7HV; 28.7HV; for the lingual, diagonal, vestibular, full ramus, and full body samples, respectively. Left sides were cut using Epker's technique, and split with an electromechanical testing machine. The higher values reached before fracture in the traction-to-fracture tests ranked to 99.1N/6.7mm; 137.2N/10.8mm; 36.2N/4.2mm; 93.0N/7.3mm; 74.0N/8.1mm; 78.1N/4.5mm; 90.9N/10.6mm; and 64.7N/4.1mm, respectively, for specimens I, II, III, IV, V, VI, VII and VIII. This study provides to our knowledge the first biomechanical characteristics of SSRO and proposes a reproducible method for evaluation.

Biological attenuation of arsenic and iron in a continuous flow bioreactor treating acid mine drainage (AMD).

Passive water treatments based on biological attenuation can be effective for arsenic-rich acid mine drainage (AMD). However, the key factors driving the biological processes involved in this attenuation are not well-known. Here, the efficiency of arsenic (As) removal was investigated in a bench-scale continuous flow channel bioreactor treating As-rich AMD (∼30-40 mg L-1). In this bioreactor, As removal proceeds via the formation of biogenic precipitates consisting of iron- and arsenic-rich mineral phases encrusting a microbial biofilm. Ferrous iron (Fe(II)) oxidation and iron (Fe) and arsenic removal rates were monitored at two different water heights (4 and 25 mm) and with/without forced aeration. A maximum of 80% As removal was achieved within 500 min at the lowest water height. This operating condition promoted intense Fe(II) microbial oxidation and subsequent precipitation of As-bearing schwertmannite and amorphous ferric arsenate. Higher water height slowed down Fe(II) oxidation, Fe precipitation and As removal, in relation with limited oxygen transfer through the water column. The lower oxygen transfer at higher water height could be partly counteracted by aeration. The presence of an iridescent floating film that developed at the water surface was found to limit oxygen transfer to the water column and delayed Fe(II) oxidation, but did not affect As removal. The bacterial community structure in the biogenic precipitates in the bottom of the bioreactor differed from that of the inlet water and was influenced to some extent by water height and aeration. Although potential for microbial mediated As oxidation was revealed by the detection of aioA genes, removal of Fe and As was mainly attributable to microbial Fe oxidation activity. Increasing the proportion of dissolved As(V) in the inlet water improved As removal and favoured the formation of amorphous ferric arsenate over As-sorbed schwertmannite. This study proved the ability of this bioreactor-system to treat extreme As concentrations and may serve in the design of future in-situ bioremediation system able to treat As-rich AMD.

Phytostabilization of a metal contaminated sandy soil. II: Influence of compost and/or inorganic metal immobilizing soil amendments on metal leaching.

A lysimeter approach (under natural climatologic conditions) was used to evaluate the effect of four metal immobilizing soil treatments [compost (C), compost+cyclonic ashes (C+CA), compost+cyclonic ashes+steel shots (C+CA+SS)) and cyclonic ashes+steel shots (CA+SS)] on metal leaching through an industrially contaminated soil. All treatments decreased Zn and Cd leaching. Strongest reductions occurred after CA+SS and C+CA+SS treatments (Zn: -99.0% and -99.2% respectively; Cd: -97.2% and -98.3% respectively). Copper and Pb leaching increased after C (17 and >30 times for Cu and Pb respectively) and C+CA treatment (4.4 and >3.7 times for Cu and Pb respectively). C+CA+SS or CA+SS addition did not increase Cu leaching; the effect on Pb leaching was not completely clear. Our results demonstrate that attention should be paid to Cu and Pb leaching when organic matter additions are considered for phytostabilization of metal contaminated soils.

Phytostabilization of a metal contaminated sandy soil. I: Influence of compost and/or inorganic metal immobilizing soil amendments on phytotoxicity and plant availability of metals.

In a lysimeter set-up, compost addition to an industrial contaminated soil slightly reduced phytotoxicity to bean seedlings. The "Phytotoxicity Index" (on a scale from 1 to 4) decreased from 3.5 to 2.8. The same treatment also reduced metal accumulation in grasses: mean Zn, Cd and Pb concentrations decreased respectively from 623 to 135, from 6.2 to 1.3 and from 10.7 to <6 mg kg-1 dry weight. When combined with inorganic metal immobilizing amendments, compost had a beneficial effect on plant responses additional to the inorganic amendments alone. Best results were obtained when using compost (C)+cyclonic ashes (CA)+steel shots (SS). The "Phytotoxicity Index" decreased to 1.7, highest diversity of spontaneously colonizing plants occurred, and metal accumulation in grasses reduced to values for uncontaminated soils. Based on the first year evaluation, C+CA+SS showed to be an efficient treatment for amendment assisted phytostabilization of the contaminated Overpelt soil.

Effects of road runoff on biomass and metabolic activity of periphyton in experimental streams.

Aquatic ecosystems could be enriched with inorganic and organic matters after road runoff discharge. In this context, we studied the effects of road runoff on river biofilms (periphyton). To operate under controlled conditions the experiments were carried out in two indoor experimental streams. Glass slides were used as artificial substrates for the periphyton colonisation in the experimental streams. Current velocity was maintained at 12 cms(-1) (slow) in the first experimental stream and at 50 cms(-1) (fast) in the second one. The periphyton communities were periodically exposed to road runoff over 30 days. For this experiment, the road runoff was collected in settling basins of a motorway during rainfall events. The runoff was then characterised according to physical and chemical parameters. We tested two exposure durations (1 and 4 h) and two runoff dilutions (10% and 50%). Two laboratory experiments carried out during this study revealed that the biomass (AFDW: 0.92-2.83 g m(-2)), the chlorophyll a content (6.8-78.9 mg m(-2)) and the metabolic activity (net primary production: 61-334 m gO(2) m(-2)h(-1) and respiration: 17.2-68.3 mg O(2) m(-2) h(-1)) of the biofilms increased (p < 0.05). However, this was a function of current velocity, the runoff exposure duration, and the content in organic and inorganic elements present in the tested rainwater. Experimental streams constituted a simplified natural system, which did not allow the reproduction of all the environmental conditions. Thus, these experiments should be performed on natural sites.

Feasibility of magnetic activation of a maxillofacial distraction osteogenesis, design of a new device.

PURPOSE: Distraction osteogenesis is a technique of bone lengthening which uses the bone's natural healing process. Current devices for craniofacial distraction require a transmucosal or transcutaneous activator and are associated with numerous complications. The aim of this study was to evaluate the feasibility of a rodless magnetic activation device that could be used in craniofacial distraction. METHODS: The method is based on the torque applied between two unaligned permanent magnets. This torque depends on magnet size, shape, composition, magnetization and distance between the two magnets. Using a configuration close to that which would be applied in actual distraction osteogenesis (in terms of the distance between the two magnets), we performed an analytical study and evaluated the results. RESULTS: We observed good agreement between the model and the experimental results, finding that the transmitted force value is comparable to the force required in mandibular distraction. Thus, we proposed a design of a new distracting device consisting of a cylindrical permanent magnet diametrically magnetized and fixed to an endless screw along its main axis. Activation of the distraction motion is achieved through interaction of the first magnet with a second cylindrical magnet whose magnetization is orthogonal to its main axis and to the device's endless screw. CONCLUSION: This preliminary study demonstrates that magnetic activation for mandibular osteogenic distraction is feasible and that device size is not a constraint. We propose a prototypic device.

[Reduction of kidney prostaglandin synthesis in patients with essential hypertension. Stimulating effect of cicletanine]. / Diminution de la synthèse rénale des prostaglandines chez l'hypertendu essentiel. Effet stimulateur du ciclétanine.

The purpose of this study was to evaluate the level of renal synthesis of vasodilator and natriuretic prostaglandins I2 and E2 in patients with essential hypertension and to test the effect of cicletanine, a new antihypertensive drug, on the renal synthesis of these prostanoids in hypertensive patients. The first part of the study was carried out in 12 healthy normotensive subjects and in 25 patients of both sexes with essential hypertension. The effect of cicletanine administered in dose of 150 mg was assessed in 10 healthy volunteers and 12 hypertensive patients. The urinary levels of prostaglandins 6-keto-PGF1 alpha (a metabolite of prostacyclin PGI2) and PGE2 were measured (HPLC) by radioimmunoassay after extraction and chromatographic separation. In normal subjects the urinary excretion rate of 6-keto-PGF1 alpha was 134 +/- 26 pg/min and that of PGE2 was 180 +/- 25 pg/min. The corresponding values were significantly lower in hypertensive patients. This defect of PGI2 and PGE2 renal synthesis was found in 64 p. 100 and 72 p. 100 respectively of patients with hypertension. Cicletanine increased the urinary excretion of 6-keto-PGF1 alpha by 45 p. 100 and that of PGE2 by 59 p. 100 in hypertensive patients. It also brought to normal limits the secretion of these prostanoids in these subjects. At the dose of 150 mg the drug stimulated natriuresis significantly and increased glomerular filtration in patients with essential hypertension. This renal effect of cicletanine was acutely reduced by the presence of indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Intestinal bacterial flora in patients with colopathies. Study of samples obtained by colonoscopy]. / Microbisme intestinal de sujets atteints de colopathies. Etude de prélèvements recueilis par coloscopie

This enquiry, the limits of which are easy to determine, permits one to note that in patients with chronic hemorrhagic colonic disease samples of digestive juice, carried, out at the level of the colonic mucosa, permit isolation of a large number of pseudomonadaceae, these bacteria are extremely various. A single patient may harbour 10 to 12 species. These bacteria, usually harmless, belong to the natural microbiocenoses, but they may under certain circumstances, increase in number and, according to Fabiani, induce severe symptoms or even be fatal. The mass of bacteria isolated and identified did not permit a study of bacterial sensitivity. The most seriously affected subjects clinically, usually had various bacteria which excludes the accusation of one species and eliminates any idea of bacterial specificity in the constitution of the syndromes observed. The disturbance seems to be a consequence of these chronic diseases and not the cause. In fact, no pathogenic germ was isolated, which one might consider to be responsible for the disease. Finally, it is wise to conclude that patients with irritable colon syndromes who formed part of this investigation, simply presented some imbalance in the bacterial flora which was sometimes very marked with a predominance of proteolytic Pseudomonas.