Caged mudsnail Potamopyrgus antipodarum (Gray) as an integrated field biomonitoring tool: exposure assessment and reprotoxic effects of water column contamination.

This study highlights the usefulness of gastropods for water quality monitoring. Gastropods were caged upstream and downstream of an effluent discharge. Exposure was assessed by measurement of organic contaminants in water. Contamination of the Potamopyrgus antipodarum mudsnail was also measured using innovative techniques at the end of the 42 days of exposure. Biological effects were measured at the individual level (growth, reproduction) and subindividual level (energy reserves, vitellin-like proteins, steroid levels, expression of genes involved in estrogen signaling pathways), thus providing a better understanding of reprotoxic effects. The effluent was mainly contaminated by pharmaceutical compounds, as was the mudsnail. The highest concentrations were measured for oxazepam and were higher than 2 mg/kg downstream of the effluent discharge. Alkylphenols, bisphenol A, and vertebrate-like sex-steroid hormones were also bioaccumulated by the mudsnail downstream of the effluent. The combined use of water and snail contamination provided a complete exposure assessment. Exposure was further linked to biological effects. The mudsnail was shown to be a better adapted species for in situ exposures than Valvata piscinalis. Reproduction was sharply decreased after 6 weeks of exposure in the mudsnail. Feeding issues were excluded, confirming the toxic origin. These effects were related to estrogen signaling pathways using genomic analysis. Genes coding for proteins involved in nongenomic signaling pathways were inhibited, and those of genomic pathway repressors were induced. These results suggest that the chemical contamination due to the effluent discharge altered steroid control of reproduction and blocked the transition between oocyte and unshelled embryo, resulting in a drastic decrease of embryo production, while survival was not affected.

Removal of the herbicide 2,4-dichlorophenoxyacetate from water to zinc-aluminium-chloride layered double hydroxides.

Batch sorption studies were conducted to investigate the potential of [Zn-Al-Cl] layered double hydroxides (LDHs) for the removal of the herbicide 2,4-dichlorophenoxyacetate (2,4-D) from contaminated aqueous solutions. Experiments were performed at different pH values, initial pesticide concentration, solid/pesticide ratio and anion exchange capacity of LDHs. The LDH samples evaluated had very high retention capacity for 2,4-D whose removal was a rapid process, as a quasi-equilibrium state was reached after 1-h reaction time. The adsorption can be described by Langmuir-type isotherms, with an average affinity constant of 12.5 L mmol(-1). At initial 2,4-D concentrations between 0.08 and 4 m molL(-1), the solids removed up to 98% of the pesticide. Physicochemical characterization of the LDH solids, both fresh and after removal of 2,4-D, by X-ray diffraction, infrared spectroscopy and thermogravimetry, indicates that the retention of 2,4-D is done by adsorption on the surface of the solid for low 2,4-D concentrations. However, a combination of surface adsorption and interlayer ion exchange takes place when the 2,4-D concentration is high.

Syntheses and Thermal and Chemical Behaviors of Tartrate and Succinate Intercalated Zn(3)Al and Zn(2)Cr Layered Double Hydroxides.

Tartrate and succinate anions have been intercalated in Zn(3)Al and Zn(2)Cr LDHs. The preparations using either coprecipitation, anion exchange, or reconstruction methods are described. In the case of tartrate-containing LDH, coprecipitation and reconstruction methods have proved to be very limited to lead to pure materials due to the particular reactivity of tartrate anions. Intercalation of both anions under room-temperature conditions gives rise to expanded LDH with similar basal spacing. Moderate thermal treatments lead in all cases to a reorientation of the anions in the interlayer domains associated with an interlayer contraction occurring around 80 degrees C. The structural characterization, the thermal evolution, and the chemical stability of all the phases are studied by PXRD, FTIR, TGA, and DTA.

[Upper tibial osteotomy for degenerative arthritis of the knee with varus deformity.-A review of 250 cases. (author's transl)]. / Ostéotomies tibiales de valgisation: choix d'une technique et des gestes associés a propos de 250 cas.

The authors have reviewed 250 cases of upper tibial osteotomy for varus deformity of the knee with degenerative arthritis of the medial compartment. Most of the osteotomies (136) were closing osteotomies, the remainder being opening osteotomies using a bone graft. Closing osteotomy is recommended together with an arthrolysis of the upper tibio-fibular joint instead of a fibular osteotomy. Hyper-correction appeared to be beneficial in cases with lateral ligament laxity. The authors do not recommend intra-articular cartilage shaving or meniscectomy. They advocate surgical release of the patella by division of the lateral patellar retinacula or by anterior displacement of the tibial tuberosity.