La ligne directrice de nos expériences a été l'hypothèse que l'apparition et/ou la persistance des fluctuations de longue durée entre les états silencieux et actifs dans les réseaux néocorticaux et ...une excitabilité neuronale modifiée sont les facteurs principaux de l'épileptogenèse, menant aux crises d’épilepsie avec expression comportementale. Nous avons testé cette hypothèse dans deux modèles expérimentaux différents. La déafférentation corticale chronique a essayé de répliquer la déafférentation physiologique du neocortex observée pendant le sommeil à ondes lentes. Dans ces conditions, caractérisées par une diminution de la pression synaptique et par une incidence augmentée de périodes silencieuses dans le système cortico-thalamique, le processus de plasticité homéostatique augmente l’excitabilité neuronale. Par conséquent, le cortex a oscillé entre des périodes actives et silencieuses et, également, a développé des activités hyper-synchrones, s'étendant de l’hyperexcitabilité cellulaire à l'épileptogenèse focale et à des crises épileptiques généralisées. Le modèle de stimulation sous-liminale chronique (« kindling ») du cortex cérébral a été employé afin d'imposer au réseau cortical une charge synaptique supérieure à celle existante pendant les états actifs naturels - état de veille ou sommeil paradoxal (REM). Dans ces conditions un mécanisme différent de plasticité qui s’est exprimé dans le système thalamo-corticale a imposé pour des longues périodes de temps des oscillations continuelles entre les époques actives et silencieuses, que nous avons appelées des activités paroxysmiques persistantes. Indépendamment du mécanisme sous-jacent de l'épileptogenèse les crises d’épilepsie ont montré certaines caractéristiques similaires : une altération dans l’excitabilité neuronale mise en évidence par une incidence accrue des décharges neuronales de type bouffée, une tendance constante vers la généralisation, une propagation de plus en plus rapide, une synchronie augmentée au cours du temps, et une modulation par les états de vigilance (facilitation pendant le sommeil à ondes lentes et barrage pendant le sommeil REM). Les états silencieux, hyper-polarisés, de neurones corticaux favorisent l'apparition des bouffées de potentiels d’action en réponse aux événements synaptiques, et l'influence post-synaptique d'une bouffée de potentiels d’action est beaucoup plus importante par rapport à l’impacte d’un seul potentiel d’action. Nous avons également apporté des évidences que les neurones néocorticaux de type FRB sont capables à répondre avec des bouffées de potentiels d’action pendant les phases hyper-polarisées de l'oscillation lente, propriété qui peut jouer un rôle très important dans l’analyse de l’information dans le cerveau normal et dans l'épileptogenèse. Finalement, nous avons rapporté un troisième mécanisme de plasticité dans les réseaux corticaux après les crises d’épilepsie - une diminution d’amplitude des potentiels post-synaptiques excitatrices évoquées par la stimulation corticale après les crises - qui peut être un des facteurs responsables des déficits comportementaux observés chez les patients épileptiques. Nous concluons que la transition incessante entre des états actifs et silencieux dans les circuits cortico-thalamiques induits par disfacilitation (sommeil à ondes lentes), déafférentation corticale (épisodes ictales à 4-Hz) ou par une stimulation sous-liminale chronique (activités paroxysmiques persistantes) crée des circonstances favorables pour le développement de l'épileptogenèse. En plus, l'augmentation de l’incidence des bouffées de potentiels d’actions induisant une excitation post-synaptique anormalement forte, change l'équilibre entre l'excitation et l'inhibition vers une supra-excitation menant a l’apparition des crises d’épilepsie.
The guiding line in our experiments was the hypothesis that the occurrence and / or the persistence of long-lasting fluctuations between silent and active states in the neocortical networks, together with a modified neuronal excitability are the key factors of epileptogenesis, leading to behavioral seizures. We addressed this hypothesis in two different experimental models. The chronic cortical deafferentation replicated the physiological deafferentation of the neocortex observed during slow-wave sleep (SWS). Under these conditions of decreased synaptic input and increased incidence of silent periods in the corticothalamic system the process of homeostatic plasticity up-regulated cortical cellular and network mechanisms and leaded to an increased excitability. Therefore, the deafferented cortex was able to oscillate between active and silent epochs for long periods of time and, furthermore, to develop highly synchronized activities, ranging from cellular hyperexcitability to focal epileptogenesis and generalized seizures. The kindling model was used in order to impose to the cortical network a synaptic drive superior to the one naturally occurring during the active states - wake or rapid eye movements (REM) sleep. Under these conditions a different plasticity mechanism occurring in the thalamo-cortical system imposed long-lasting oscillatory pattern between active and silent epochs, which we called outlasting activities. Independently of the mechanism of epileptogenesis seizures showed some analogous characteristics: alteration of the neuronal firing pattern with increased bursts probability, a constant tendency toward generalization, faster propagation and increased synchrony over the time, and modulation by the state of vigilance (overt during SWS and completely abolished during REM sleep). Silent, hyperpolarized, states of cortical neurons favor the induction of burst firing in response to depolarizing inputs, and the postsynaptic influence of a burst is much stronger as compared to a single spike. Furthermore, we brought evidences that a particular type of neocortical neurons - fast rhythmic bursting (FRB) class - is capable to consistently respond with bursts during the hyperpolarized phase of the slow oscillation, fact that may play a very important role in both normal brain processing and in epileptogenesis. Finally, we reported a third plastic mechanism in the cortical network following seizures - a decreasing amplitude of cortically evoked excitatory post-synaptic potentials (EPSP) following seizures - which may be one of the factors responsible for the behavioral deficits observed in patients with epilepsy. We conclude that incessant transitions between active and silent states in cortico-thalamic circuits induced either by disfacilitation (sleep), cortical deafferentation (4-Hz ictal episodes) and by kindling (outlasting activities) create favorable circumstances for epileptogenesis. The increase in burst-firing, which further induce abnormally strong postsynaptic excitation, shifts the balance of excitation and inhibition toward overexcitation leading to the onset of seizures.
The turbot Psetta maeotica (Pallas, 1814) is a demersal species that populates the Romanian Black Sea's continental shelf and is an important segment of the regional fishing potential under the ...aspect of market demand, both on the national and international level. Being a migratory species (short, coast - perpendicular migrations, made for reproduction) it uses during its complete biological cycle various habitat types, among which we mention: reproduction habitats (coastal waters, down to 30 meters depth), growing habitats (close to the sea bottom, down to 50-60 meters depth), wintering habitats (close to the sea bottom, down to 60-80 meters depth). The turbot populates almost all the habitat types present down to these depths, but it prefers the sandy and muddy ones, that are found especially in the Central and Northern part of Romanian littoral. The physical, chemical and biological characterization of these habitats revealed an improving tendency, that appeared on the bases of economical activities restructuring, the growing of the exigencies in implementing the environmental policies, the setting-up of marine protected areas and also the new reglementations regarding the marine resources exploitation.
The European Common Fisheries Policy aims to gradually eliminate discards in all European Union fisheries through the introduction of a landing obligation for all catches of species subject to catch ...limits (turbot and sprat for the Black Sea). In 2016, the Commission established a discard plan for turbot fisheries in the Black Sea, that provided for a survivability exemption of turbot caught with bottom-set gillnets, applied from 1 January 2017 until 31 December 2019. Subsequently, Romania and Bulgaria submitted an updated Joint Recommendation to the Commission, requesting the renewal of the discard plan and the survivability exemption based on the high survival rates of this species. The Scientific, Technical and Economic Committee for Fisheries (STECF) acknowledged the existence of data demonstrating the high survivability of turbot caught by vessels from non-EU countries using the same gears, however they requested that Member States concerned should submit additional data on survival estimates relating to the gillnet fishery for turbot. In this context, NIMRD “Grigore Antipa“ was commissioned by the Romanian National Agency for Fisheries and Aquaculture (NAFA) to perform a pilot study aiming at obtaining scientific evidence for the exemption of turbot from the landing obligation, carried-out during January-April 2022. Scientific fishing was performed in the Romanian marine area with specialized gears - turbot gillnets on board of NIMRD’s boat. The methodology consisted of launching the gillnets in established locations and recovering them after a soaking time depending on weather conditions. After each operation to recover the nets from the water, all turbot specimens caught were retained on board, parked in a fiber-reinforced polymer (FRP) container filled with seawater and equipped with an aeration system. The specimens were kept in the tank for 1 hour, during which time they were monitored from the point of view of their condition (dead, alive, injuries, other negative effects produced by the fishing gear). Subsequently, all turbot specimens declared viable were released back into the sea. The results indicate high survivability rates of turbot caught in gillnets (81.67%). Some injuries were reported in the dead specimens, probably caused by the mechanical action of the gear.
Urethral Stents Geavlete, Petrişor; Mulţescu, Răzvan; Niţă, Gheorghe ...
Endoscopic Diagnosis and Treatment in Urethral Pathology,
01/2016
Book Chapter
RESEARCH AND SCIENCE TODAY is a biannual science journal established in 2011. The journal is an informational platform that publishes assessment articles and the results of various scientific ...research carried out by academics. We provide the authors with the opportunity to create and/or perfect their science writing skills. Thus, each issue of the journal (two per year and at least two supplements) will contain professional articles from any academic field, authored by domestic and international academics. The goal of this journal is to pass on relevant information to undergraduate, graduate, and post-graduate students as well as to fellow academics and researchers; the topics covered are unlimited, considering its multi-disciplinary profile. Regarding the national and international visibility of Research and Science Today, it is indexed in over 30 international databases (IDB) and is present in over 200 online libraries and catalogues; therefore, anybody can easily consult the articles featured in each issue by accessing the databases or simply the website.
Value of a second TUR in bladder tumours evaluation and treatment Geavlete, Petrisor; Jora, Toni; Georgescu, Dragos ...
European urology supplements : official journal of the European Association of Urology,
2002, 2002-1-00, Letnik:
1, Številka:
1
Journal Article
Cold retrograde endoincision in upper urinary tract stenosis Geavlete, Petrisor; Nitâ, Gheorghe; Mirciulescu, Victor ...
European urology supplements : official journal of the European Association of Urology,
2002, 2002-1-00, Letnik:
1, Številka:
1
Journal Article
Chapter 3 - Urethral Stents Geavlete, Petrişor; Mulţescu, Răzvan; Niţă, Gheorghe ...
Endoscopic Diagnosis and Treatment in Urethral Pathology,
2016
Book Chapter
The first descriptions of urethro-vesical catheters date back to antiquity, when straws or palm leaves were used for this purpose. In China, Sun Shimiao (581–682 AD) used tubular leaves from green ...onions through which air was blown to remove the obstacle. In 1036, Avicenna sensed the need for gentle insertion of catheters and created flexible models from animal skin, treated with ox blood for firmness and lubricated with cheese. The aim of modern medicine was the development of a prosthesis, which, inserted into the urethra, would achieve recalibration only for the stenosed segment.
