Selection of an adsorbent for lead removal from drinking water by a point-of-use treatment device.

The removal of lead from drinking water was investigated to develop a point-of-use water filter that could meet the regulation imposed by the new European Directive 98-83 lowering lead concentration in drinking water below 10 microgL(-1). The objective of this research was to assess the potential of different adsorbents (zeolites, resins, activated carbon, manganese oxides, cellulose powder) to remove lead from tap water with a very short contact time. To begin, the repartition of the lead species in a tap water and a mineral water was computed with the computer model CHESS. It showed that in bicarbonated waters lead is mainly under lead carbonate form, either in the aqueous or in the mineral phase. Batch experiments were then conducted to measure the equilibrium adsorption isotherms of the adsorbents. Then, for five of them, dynamic experiments in micro-columns were carried out to assess the outlet lead concentration level. Three adsorbents gave rise to a leakage concentration lower than 10 microgL(-1) and were then selected for prototypes experiments: chabasite, an activated carbon coated with a synthetic zeolite and a natural manganese oxide. The proposed method clearly showed that the measurement of equilibrium isotherms is not sufficient to predict the effectiveness of an adsorbent, and must be coupled with dynamic experiments.

9-Carboxymethyl-5H,10H-imidazo[1,2-a]indeno[1,2-e]pyrazin-4-one-2-carbocylic acid (RPR117824): selective anticonvulsive and neuroprotective AMPA antagonist.

Excessive release of glutamate, a potent excitatory neurotransmitter, is thought to play an important role in a variety of acute and chronic neurological disorders, suggesting that excitatory amino acid antagonists may have broad therapeutic potential in neurology. Here, we describe the synthesis, pharmacological properties and neuroprotective activity of 9-carboxymethyl-imidazo-[1-2a]indeno[1-2e]pyrazin-4-one-2-carboxylic acid (RPR117824), an original selective AMPA antagonist. RPR117824 can be obtained through a six-step synthesis starting from (1-oxo-indan-4-yl) acetic acid, which has been validated on a gram-scale with an overall yield of 25%. Monosodium or disodium salts of the compound exhibit excellent solubility in saline (> or = 10 g/L), enabling intravenous administration. RPR117824 displays nanomolar affinity (IC(50)=18 nM) for AMPA receptors and competitive inhibition of electrophysiological responses mediated by AMPA receptors heterologously expressed in Xenopus oocytes (K(B)=5 nM) and native receptors in rat brain slices (IC(50)=0.36 microM). In in vivo testing, RPR117824 behaves as a powerful blocker of convulsions induced in mice or rats by supramaximal electroshock or chemoconvulsive agents such as pentylenetetrazole, bicuculline, isoniazide, strychnine, 4-aminopyridine and harmaline with half maximal effective doses ranging from 1.5 to 10 mg/kg following subcutaneous or intraperitoneal administration. In disease models in rats and gerbils, RPR117824 possesses significant neuroprotective activity in global and focal cerebral ischemia, and brain and spinal cord trauma.