Integrated electrochemical biosensor based on algal metabolism for water toxicity analysis.

An autonomous electrochemical biosensor with three electrodes integrated on the same silicon chip dedicated to the detection of herbicides in water was fabricated by means of silicon-based microfabrication technology. Platinum (Pt), platinum black (Pt Bl), tungsten/tungsten oxide (W/WO3) and iridium oxide (Pt/IrO2) working ultramicroelectrodes were developed. Ag/AgCl and Pt electrodes were used as reference and counter-integrated electrodes respectively. Physical vapor deposition (PVD) and electrodeposition were used for thin film deposition. The ultramicroelectrodes were employed for the detection of O2, H2O2 and pH related ions H3O(+)/OH(-), species taking part in photosynthetic and metabolic activities of algae. By measuring the variations in consumption-production rates of these electroactive species by algae, the quantity of herbicides present at trace level in the solution can be estimated. Fabricated ultramicroelectrodes were electrochemically characterized and calibrated. Pt Black ultramicroelectrodes exhibited the greatest sensitivity regarding O2 and H2O2 detection while Pt/IrO2 ultramicroelectrodes were more sensitive for pH measurement compared to W/WO3 ultramicroelectrodes for pH measurement. Bioassays were then conducted to detect traces of Diuron herbicide in water samples by evaluating disturbances in photosynthetic and metabolic activities of algae caused by this herbicide.

[Horton's disease and rhizomelic pseudopolyarthritis. Developmental data apropos of 95 cases]. / Maladie de Horton et pseudopolyarthrite rhizomélique. Données évolutives à propos de 95 cas.

The many common factors linking rhizomelic pseudopolyarthritis and Horton's disease prompt to compare their respective evolutions and the long-term results of their treatments. The comparative study of 28 patients with temporal Horton's arteritis, proven histologically, and 28 rhizomelic pseudopolyarthritis without arteritis on biopsy, in a total population of 95 patients, confirms the similarity of their clinical and biological signs and show a closely related evolution in the three groups. The evolution leads to a cure approximately 16.4 +/- 14 months in 41 p. cent of the cases. 34 p. cent of the patients are at an advanced stage with a mean follow-up of 37 months and relapses during the weaning period were frequent. 25 p. cent of the patients died. Most deaths occur in the first month of the disease, and occur readily in patients who have received a short treatment with steroids discontinued because of a iatrogenic accident. Cerebral vascular accidents and coronary accidents, arterial hypertension and iatrogenic gastro-intestinal ulcerations are the most frequent complications.