ATP signalling in epilepsy

This paper focuses on a role for ATP neurotransmission and gliotransmission in the pathophysiology of epileptic seizures. ATP along with gap junctions propagates the glial calcium wave, which is an extraneuronal signalling pathway in the central nervous system. Recently astrocyte intercellular calcium waves have been shown to underlie seizures, and conventional antiepileptic drugs have been shown to attenuate these calcium waves. Blocking ATP-mediated gliotransmission, therefore, represents a potential target for antiepileptic drugs. Furthermore, while knowledge of an antiepileptic role for adenosine is not new, a recent study showed that adenosine accumulates from the hydrolysis of accumulated ATP released by astrocytes and is believed to inhibit distant synapses by acting on adenosine receptors. Such a mechanism is consistent with a surround-inhibitory mechanism whose failure would predispose to seizures. Other potential roles for ATP signalling in the initiation and spread of epileptiform discharges may involve synaptic plasticity and coordination of synaptic networks. We conclude by making speculations about future developments

Neuroprotection by adenosine in the brain: From A1 receptor activation to A2A receptor blockade

Adenosine is a neuromodulator that operates via the most abundant inhibitory adenosine A1 receptors (A1Rs) and the less abundant, but widespread, facilitatory A2ARs. It is commonly assumed that A1Rs play a key role in neuroprotection since they decrease glutamate release and hyperpolarize neurons. In fact, A1R activation at the onset of neuronal injury attenuates brain damage, whereas its blockade exacerbates damage in adult animals. However, there is a down-regulation of central A1Rs in chronic noxious situations. In contrast, A2ARs are up-regulated in noxious brain conditions and their blockade confers robust brain neuroprotection in adult animals. The brain neuroprotective effect of A2AR antagonists is maintained in chronic noxious brain conditions without observable peripheral effects, thus justifying the interest of A2AR antagonists as novel protective agents in neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease, ischemic brain damage and epilepsy. The greater interest of A2AR blockade compared to A1R activation does not mean that A1R activation is irrelevant for a neuroprotective strategy. In fact, it is proposed that coupling A2AR antagonists with strategies aimed at bursting the levels of extracellular adenosine (by inhibiting adenosine kinase) to activate A1Rs might constitute the more robust brain neuroprotective strategy based on the adenosine neuromodulatory system. This strategy should be useful in adult animals and especially in the elderly (where brain pathologies are prevalent) but is not valid for fetus or newborns where the impact of adenosine receptors on brain damage is different

Effect of mineralogy on the beneficiation of REE from heavy mineral sands: The case of Nea Peramos, Kavala, northern Greece

Beneficiation of a rare earth element (REE) ore from heavy mineral (HM) sands by particle size classification in conjunction with high-intensity magnetic separation (HIMS) was investigated. The HM sands of Nea Peramos, Kavala, Northern Greece, contain high concentrations of REE accommodated mainly in silicate minerals, such as allanite. However, the potential of the Northern Greek placer for REE exploitation has not been fully evaluated due to limited on-shore and off-shore exploration drilling data. Characterization of the magnetic separation fractions using XRD and bulk ICP-MS chemical analysis showed that the magnetic products at high intensities were strongly enriched in the light REE (LREE), relative to the nonmagnetic fraction. Allanite and titanite are the major host mineral for REE in the magnetic products but mainly allanite controls the REE budget due its high concentration in LREE. SEM/EDS and ICP-MS analysis of the different particle size fractions showed LREE enrichment in the fractions −0.425 +0.212 mm, and a maximum enrichment in the −0.425 +0.300 mm. The maximum enrichment is achieved after magnetic separation of the particle size fractions. Mass balance calculations showed that the maximum REE recovery is achieved after magnetic separation of each particle size fraction separately, i.e., 92 wt.% La, 91 wt.% Ce, and 87 wt.% Nd. This new information can contribute to the optimization of beneficiation process to be applied for REE recovery from HM black sands. © 2020 by the authors; licensee MDPI, Basel, Switzerland

Pyrite oxidation by halotolerant, thermotolerant bacteria

Thermotolerant "Thiobacillus prosperus"-like bacteria were enriched from warm, acidic sediments of the island of Milos in the Aegean Sea. Analysis of 16S rRNA gene sequences indicated at least two thermotolerant species, with at least one of them present in similar niches at Vulcano, Italy. Iron solubilization in a pyrite-enrichment culture at 47 degrees C was most rapid in the presence of NaCl at 30 g.l(-1).One of the novel species (strain M7) grew in pure Culture oil pyrite with NaCl at 50 g.l(-1), but iron solubilization was most rapid with 20 g NaCl.l(-1) at just below 50 degrees C

Pyrite oxidation and copper sulfide ore leaching by halotolerant, thermotolerant bacteria

Pyrite oxidation was observed in a mixed culture of salt-tolerant, thermotolerant, acidophilic bacteria from warm, acidic, coastal sediments of the island of Milos (Greece). Analysis of 16S rRNA gene sequences cloned from DNA extracted from the mixed culture indicated two species which were related to Thiobacillus prosperus. One of the sequences was found previously in warm, sediment samples from the island of Vulcano (Italy). Iron solubilization from pyrite by the Milos culture at 47 degrees C was most rapid in the presence of NaCl at 30 g l(-1). A novel species was isolated from the mixed culture and grew in pure culture on pyrite with 50 g l(-1) NaCl, but iron solubilization was most rapid at just below 50 degrees C with 20 g l(-1) NaCl. Establishment of activity of the halotolerant, thermotolerant bacteria in copper sulfide ore leaching columns was more difficult than with related bacteria growing at lower temperatures. (c) 2010 Elsevier B.V. All rights reserved