Production of reactive oxygen species (hydroxyl radicals, superoxide radicals and hydrogen peroxide) was studied using EPR spin-trapping techniques and specific dyes in isolated plasma membranes from the growing and the non-growing zones of hypocotyls and roots of etiolated soybean seedlings as well as coleoptiles and roots of etiolated maize seedlings. NAD(P)H mediated the production of superoxide in all plasma membrane samples. Hydroxyl radicals were only produced by the membranes of the hypocotyl growing zone when a Fenton catalyst (FeEDTA) was present. By contrast, in membranes from other parts of the seedlings a low rate of spontaneous hydroxyl radical formation was observed due to the presence of small amounts of tightly bound peroxidase. It is concluded that apoplastic hydroxyl radical generation depends fully, or for the most part, on peroxidase localized in the cell wall. In soybean plasma membranes from the growing zone of the hypocotyl pharmacological tests showed that the superoxide production could potentially be attributed to the action of at least two enzymes, an NADPH oxidase and, in the presence of menadione, a quinone reductase.

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The development of treatments for acute neurodegenerative diseases (stroke and brain trauma) has focused on (i) re-establishing blood flow to ischemic areas as quickly as possible (i.e. mainly antithrombotics or thrombolytics for stroke therapy) and (ii) on protecting neurons from cytotoxic events (i.e. neuroprotective therapies such as anti-excitotoxic or anti-inflammatory agents for stroke and neurotrauma therapies). This paper reviews the preclinical data for enoxaparin in in vivo models of ischemia and brain trauma in rats. Following a photothrombotic lesion in the rat, enoxaparin significantly reduced edema at 24 h after lesion when the treatment was started up to 18 h after insult. Enoxaparin was also tested after an ischemic insult using the transient middle cerebral artery occlusion (tMCAO) model in the rat. Enoxaparin, 2´1.5 mg/kg i.v., significantly reduced the lesion size and improved the neuroscore when the treatment was started up to 5 h after ischemia. Enoxaparin, administered at 5h after insult, reduced cortical lesion size in a dose-dependent manner. In permanent MCAO, enoxaparin (5 and 24 h after insult) significantly reduced lesion size and improved neuroscore. A slight and reversible elevation of activated partial thromboplastin time (APTT) suggests that enoxaparin is neuroprotective at a non-hemorrhagic dose. Traumatic brain injury (TBI) is often accompanied by secondary ischemia due in part to edema-induced compression of blood vessels. When enoxaparin, at 0.5 mg/kg i.v. + 4´1 mg/kg s.c., was administered later than 30h after TBI, it significantly reduced edema in hippocampus and parietal cortex. At one week after TBI the lesion size was significantly reduced and the neurological deficit significantly improved in enoxaparin treated animals. Finally, the cognitive impairment was significantly improved by enoxaparin at 48 h to 2 weeks after TBI. The anticoagulant properties of unfractionated heparin and specifically enoxaparin can explain their anti-ischemic effects in experimental models. Furthermore, unfractionated heparin and specifically enoxaparin, have, in addition to anticoagulant, many other pharmacological effects (i.e. reduction of intracellular Ca 2+ release; antioxidant effect; anti-inflammatory or neurotrophic effects) that could act in synergy to explain the neuroprotective activity of enoxaparin in acute neurodegenerative diseases. Finally, we demonstrated, that in different in vivo models of acute neurodegenerative diseases, enoxaparin reduces brain edema and lesion size and improves motor and cognitive functional recovery with a large therapeutic window of opportunity (compatible with a clinical application). Taking into account these experimental data in models of ischemia and brain trauma, the clinical use of enoxaparin in acute neurodegenerative diseases warrants serious consideration.

Heterologous expression and lesioning studies were conducted to identify possible subunit assembly partners in nicotinic acetylcholine receptors (nAChR) containing ␣6 subunits (␣6* nAChR). SH-EP1 human epithelial cells were transfected with the requisite subunits to achieve stable expression of human ␣6␤2, ␣6␤4, ␣6␤2␤3, ␣6␤4␤3, or ␣6␤4␤3␣5 nAChR. Cells expressing subunits needed to form ␣6␤4␤3␣5 nAChR exhibited saturable [ 3 H]epibatidine binding (K d ϭ 95.9 Ϯ 8.3 pM and B max ϭ 84.5 Ϯ 1.6 fmol/mg of protein). The rank order of binding competition potency (K i ) for prototypical nicotinic compounds was ␣-conotoxin MII (6 nM) Ͼ nicotine (156 nM) ϳ methyllycaconitine (200 nM) Ͼ ␣-bungarotoxin (Ͼ10 M), similar to that for nAChR in dopamine neurons displaying a distinctive pharmacology. 6-Hydroxydopamine lesioning studies indicated that ␤3 and ␣5 subunits are likely partners of the ␣6 subunits in nAChR expressed in dopaminergic cell bodies. Similar to findings in rodents, quantitative real-time reverse transcription-polymerase chain reactions of human brain indicated that ␣6 subunit mRNA expression was 13-fold higher in the substantia nigra than in the cortex or the rest of the brain. Thus, heterologous expression studies suggest that the human ␣5 subunit makes a critical contribution to ␣6␤4␤3␣5 nAChR assembly into a ligand-binding form with native ␣6*-nAChR-like pharmacology and of potential physiological and pathophysiological relevance.Distinct nicotinic acetylcholine receptor (nAChR) subtypes expressed in mesostriatal dopaminergic neurons are involved in modulation of striatal dopamine (DA) release (Wonnacott, 1997;Champtiaux et al., 2002;Luetje, 2004); nAChR containing ␣4 and ␤2 subunits (␣4␤2* nAChR) or containing ␣6 subunits (␣6* nAChR) participate directly, and ␣7* nAChR participate indirectly. Whereas the biochemistry of ␣4␤2* and ␣7* nAChR is well characterized, the subunit composition and functional properties of ␣6* nAChR remain unclear. Suggested roles for ␣6* nAChR in modulation of DA transmission imply their potential importance in locomotion, reward, schizophrenia, and Parkinson's disease (le Novère et al

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A case study suggests that the use of site‐specific reactivity coefficients and chlorine consumption results in more accurate models of trihalomethane formation. Because of increasing concern about balancing health risks for microbiological control and disinfection by‐product formation, utilities are closely examining and optimizing disinfection practices. The authors present a methodology for developing site‐specific, inplant (finished water) chlorine (Cl2) residual and trihalomethane (THM) formation models. In a case study, the methodology was applied at three operating water treatment plants in the Paris suburbs. A key obstacle was the limited historical record of bromide (Br–) occurrence. However, lab chlorination experiments indicated that approximately 10 percent of Br– was typically incorporated into THMs. In‐plant Cl2 residuals were accurately simulated with a simple first‐order Cl2 consumption model. The most accurate THM simulations were obtained using a recently developed US Environmental Protection Agency model that incorporates species‐specific reactivity parameters.