Limitations of the isolated GP-STN network

An in vitro mouse slice preparation from control and MPTP-treated mice in which functional reciprocal GP-STN connectivity is maintained, does not produce oscillatory bursting or synchronous activity neuronal activity. Pharmacological interventions that produce bursting activity do so without concomitant neuronal synchrony, or a requirement for glutamate or GABA transmission. Pre-treatment with MPTP did not alter this behaviour. Thus, we have no evidence that the functionally connected, but isolated, GP — STN network can act as a pacemaker for synchronous correlated activity in the basal ganglia and must conclude that other inputs such as those from cortex and/or striatum are required.

Effect of dopamine on synchronous neuronal oscillations in the globus pallidus-subthalamic nucleus network

Changes in the pattern of activity of neurones within the basal ganglia are relevant in the pathophysiology and symptoms of Parkinson’s disease. The globus pallidus (GP) – subthalamic nucleus (STN) network has been proposed to form a pacemaker driving regenerative synchronous bursting activity. In order to test whether this activity can be sustained in vitro a 20o parasagittal slice of mouse midbrain was developed which preserved functional connectivity between the STN and GP. Mouse STN and GP cells were characterised electrophysiologically by the presence or absence of a voltage sag in response to hyperpolarising current steps indicative of Ih and the presence of rebound depolarisations. The presence of evoked and spontaneous post-synaptic GABA and glutamatergic currents indicated functional connectivity between the STN and GP. In control slices, STN cells fired action potentials at a regular rate, activity which was unaffected by bath application of the GABAA receptor antagonist picrotoxin (50 μM) or the glutamate receptor antagonist CNQX (10 μM). Paired extracellular recordings of STN cells showed uncorrelated firing. Oscillatory burst activity was induced pharmacologically using the glutamate receptor agonist, NMDA (20 μM), in combination with the potassium channel blocker apamin (50 -100 nM). The burst activity was unaffected by bath application of picrotoxin or CNQX while paired STN recordings showed uncorrelated activity indicating that the activity is not produced by the neuronal network. Thus, no regenerative activity is evident in this mouse brain preparation, either in control slices or when bursting is pharmacologically induced, suggesting the requirement of other afferent inputs that are not present in the slice. Using single-unit extracellular recording, dopamine (30 μM) produced an excitation of STN cells. This excitation was independent of synaptic transmission and was mimicked by both the Dl-like receptor agonist SKF38393 (10 μM) and the D2-like receptor agonist quinpirole (10 μM). However, the excitation was partially reduced by the D1-like antagonist SCH23390 (2 μM) but not by the D2-like antagonists sulpiride (10 μM) and eticlopride (10 μM). Using whole-recordings, dopamine was shown to induce membrane depolarisation. This depolarisation was caused either by a D1-like receptor mediated increase in a conductance which reversed at -34 mV, consistent with a non-specific cation conductance, or a D2-like receptor mediated decrease in conductance which reversed around -100 mV, consistent with a potassium conductance. Bath application of dopamine altered the pattern of the burst-firing produced by NMDA an apamin towards a more regular pattern. This effect was associated with a decrease in amplitude and ll1crease in frequency of TTX-resistant plateau potentials which underlie the burst activity.

Control of spatiotemporal chaos in catalytic CO oxidation by laser-induced pacemakers

Control of spatiotemporal chaos is achieved in the catalytic oxidation of CO on Pt(110) by localized modification of the kinetic properties of the surface chemical reaction. In the experiment, a small temperature heterogeneity is created on the surface by a focused laser beam. This heterogeneity constitutes a pacemaker and starts to emit target waves. These waves slowly entrain the medium and suppress the spatiotemporal chaos that is present in the absence of control. We compare this experimental result with a numerical study of the Krischer-Eiswirth-Ertl model for CO oxidation on Pt(110). We confirm the experimental findings and identify regimes where complete and partial controls are possible.

Suppression of spatiotemporal chaos in the oscillatory CO oxidation on Pt(110) by focused laser light

Chemical turbulence in the oscillatory catalytic CO oxidation on Pt(110) is suppressed by means of focused laser light. The laser locally heats the platinum surface which leads to a local increase of the oscillation frequency, and to the formation of a pacemaker which emits target waves. These waves slowly entrain the medium and suppress the spatiotemporal chaos present in the absence of laser light. Our experimental results are confirmed by a detailed numerical analysis of one- and two-dimensional media using the Krischer-Eiswirth-Ertl model for CO oxidation on Pt110. Different control regimes are identified and the dispersion relation of the system is determined using the pacemaker as an externally tunable wave source.

Efeitos da senescência no folheto intergeniculado do tálamo de ratos: análises morfológicas e neuroquímicas

The circadian timing system (CTS), in rodents, consists of interconnected neural structures such as the suprachiasmatic nucleus (SCN) of the hypothalamus, Intergeniculate Leaflet (IGL) of the thalamus, synchronous pathways and behavioral effectors. The SCN has been described as the major circadian pacemaker in several species of mammals, while the IGL appears to be involved in integration of photic and non-photic clues relaying them to SCN. The CTS allows an ordered internal temporal organization to the organism, providing the proper execution of physiological and behavioral mechanisms, which brings homeostasis. However, this stability is disrupted with aging process causing numerous pathological disorders, ranging from simple loss of physiological functions to decreases in cognitive performance. Therefore, is fundamental understanding the effects of senescence in this system. In this context, is proposed in this study to check if there are changes in IGL cytoarchitecture, neurochemical and retinal afferent markers with aging and their possible morpho-functional implications. To achieve this goal wistar rats were divided into 3 groups: young (3 months); Middle Age (13 months); Old (23 months). They were submitted to paraformaldhyde (4%) transcardiac perfusion to tissue fixation. Then, they had their brain removed and sectioned in 30 µm slices, which every sixth section were collected. This sections were processed by nissl method and immunostaining for GFAP, GAD, ENK, NPY and CTb in order to analyze the IGL features. It was observed a cell loss in middle age and old animals at Nissl, NPY and CTb stains. In addition, it was shown a increase in GFAP in middle aged animals compared to young and old ones. No differences were found in other neurochemichal stains. These data suggests IGL loss retinal afferents and neurons, in special the NPY-IR ones, likely having a compensatory gliogenesis. This supports the correlations between the CTS functional deficits and an anatomical deterioration of its components with the aging process.

Les valves sans suture dans le traitement de la sténose aortique sévère

Rapport présenté en vue de l’obtention du grade de M.Sc.A génie biomédical option génie clinique

Long chain diols and diol indices of surface sediments of the Iberian Atlantic margin

Long chain diols are lipids that have gained interest over the last years due to their high potential to serve as biomarkers and diol indices have been proposed to reconstruct upwelling conditions and sea surface temperature (SST). However, little is known about the sources of the diols and the mechanisms impacting their distribution. Here we studied the factors controlling diol distributions in the Iberian Atlantic margin, which is characterized by a dynamic continental shelf under the influence of upwelling of nutrient-rich cold deep waters, and fluvial input. We analyzed suspended particulate matter (SPM) of the Tagus river, marine SPM and marine surface sediments along five transects off the Iberian margin, as well as riverbank sediments and soil from the catchment area of the Tagus river. Relatively high fractional abundances of the C32 1,15-diol (normalized with respect to the 1,13- and 1,15-diols) were observed in surface sediments in front of major river mouths and this abundance correlates strongly with the BIT index, a tracer for continental input of organic carbon. Together with an even higher fractional abundance of the C32 1,15-diol in the Tagus river SPM, and the absence of long chain diols in the watershed riverbank sediments and soils, we suggest that this long chain diol is produced in-situ in the river. Further support for this hypothesis comes from the small but distinct stable carbon isotopic difference of 1.3? with the marine C28 1,13-diol. The 1,14-diols are relatively abundant in surface sediments directly along the northern part of the coast, close to the upwelling zone, suggesting that Diol Indices based on 1,14-diols would work well as upwelling tracers in this region. Strikingly, we observed a significant difference in stable carbon isotopic composition between the monounsaturated C30:1 1,14- and the saturated C28 1,14-diol (3.8±0.7 per mil), suggesting different sources, in accordance with their different distributions. In addition, the Long chain Diol Index (LDI), a proxy for sea surface temperature, was applied for the surface sediments. The results correlate well with satellite SSTs offshore but reveal a significant discrepancy with satellite-derived SSTs in front of the Tagus and Sado rivers. This suggests that river outflow might compromise the applicability of this proxy.

Survenue des arythmies et troubles de conduction après un remplacement de la valve aortique par cathéter : incidence et impact

La sténose aortique est la cardiopathie valvulaire la plus fréquente retrouvée chez les patients agés. Suite à l’apparition des symptômes, la survie des patients diminue de façon drastique en l’absence d’un remplacement valvulaire aortique. Cependant, une proportion considérable de ces patients n’est pas opérée en raison d’un risque chirurgical élevé, l’âge étant l’une des principales raisons de refus d’un remplacement valvulaire aortique chirurgical. Ce défaut dans la prise en charge des ces patients a favorisé le développement du remplacement valvulaire aortique par cathéter où implantation valvulaire aortique par cathèter (TAVR ou TAVI), qui a représenté une révolution dans le traitement de la sténose aortique. Cette intervention est actuellement un traitement de routine chez les patients à haut risque chirurgical atteints d’une sténose aortique, même si la chirurgie cardiaque n’est pas contre-indiquée. Ces dernières années ont vu un changement de profil des candidats potentiels vers une population à plus faible risque. Cependant, plusieurs préoccupations demeurent. L’une des plus importantes est la survenue des arythmies et de troubles de conduction, notamment le bloc de branche gauche et le bloc auriculo-ventriculaire, qui sont des complications fréquemment associées au TAVR. Malgré l’évolution de la technologie et le développement de nouveaux dispositifs réduisant le taux global de complications, aucune amélioration n’a pas été intégrée pour prévenir l’apparition de telles complications. De plus, l’utilisation de certains dispositifs de nouvelle génération semble être associée à un risque accru de troubles de conduction, et par conséquent, l’incidence de ces complications pourrait augmenter dans le futur. Cependant, L’impact et l’évolution de ces complications sont inconnus. Ce travail de recherche évalue l’incidence et l’évolution des troubles de conduction suite au TAVR et l’impact des blocs de branche gauche de novo et de l’implantation d’un pacemaker sur les résultats cliniques et échocardiographiques.

Follow-up telefónico ao doente portador de dispositivo cardíaco

A implantação de um pacemaker (PMD) ou de um cardioversor desfibrilhador (CDI) tornou-se num procedimento comum e relativamente simples, como tratamento para disritmias cardíacas. Apesar da implantação não implicar uma alteração importante no estilo de vida, está inerente a algumas preocupações e sentimentos de ansiedade, relacionadas sobretudo com as atividades de vida diária. A equipa de enfermagem do Serviço de Cardiologia do Hospital Fernando Fonseca mantém em funcionamento uma consulta de enfermagem ao portador de PMD e/ou CDI desde 2000. Nos últimos anos foram sendo realizadas algumas alterações no sentido de melhorar a consulta e os cuidados prestados a estes doentes. A consulta é realizada por enfermeiros com treino e experiência na área da aritmologia, ocorrendo 4-6 semanas após a implantação do referido dispositivo. Numa primeira consulta constatamos que muitos doentes, durante este período, limitaram ao máximo as suas atividades de vida aguardando pela consulta para esclarecer as suas dúvidas. De forma a encurtar o tempo entre a implantação do dispositivo e a 1ª consulta, a equipa de enfermagem implementou, em Janeiro de 2016 o follow-up telefónico, encontrando-se em fase de teste. Este follow-up é feito cerca de uma semana após a implantação do dispositivo e tem como objetivos fazer uma breve avaliação do estado do doente, despistar eventuais sinais inflamatórios da sutura operatória, fazer alguns ensinos, esclarecer dúvidas e, em caso de necessidade, encaminhar o doente aos cuidados de saúde, se a situação assim o justificar. A análise preliminar que fazemos foi bastante positivo tendo em conta o feed-back obtido pelos doentes /família. Neste contato telefónico foi possível resolver questões, algumas delas geradoras de ansiedade e, despistar eventuais situações de eventual infecção do local cirúrgico. Futuramente iremos reorganizar a consulta de enfermagem de forma a introduzir esta atividade contribuindo assim para a melhoria da qualidade dos cuidados.

Consulta de Enfermagem ao doente portador de PMD e CDI

Os cuidados de saúde sempre se pautaram por uma indissociável ligação ao constante desenvolvimento do conhecimento científico médico e de enfermagem, com a particularidade de, nos últimos anos, ter sido acompanhado por um desenvolvimento biotecnológico que tem permitido melhorar a qualidade de vida dos portadores de doença crónica, nomeadamente os indivíduos com patologia cardíaca. Através da evolução dos dispositivos implantáveis como pacemakers, cardioversores desfibrilhadores e geradores de ressincronização cardíaca, foi possível prolongar a vida e melhorar a sua qualidade em doenças que no início do século XX matavam muitas pessoas. Apesar da implantação destes dispositivos não implicar uma alteração importante no estilo de vida, está inerente a algumas preocupações e sentimentos de ansiedade, relacionadas sobretudo com as actividades de vida diária. Estas preocupações e focos de ansiedade podem resultar de mitos, falta de informação e desenvolvimento de ideias erradas acerca da vida enquanto portador de um dispositivo (BEERY et al., 2002; WOOD & ELLENBOGEN, 2002; WOODRUFF & PRUDENTE, 2005; MALM et al., 2007). O principal foco do desenvolvimento de mitos relacionados com a vida enquanto portadores de dispositivos de pacing e desfibrilhação, está relacionado com a (des)informação fornecida por não profissionais de saúde que integram o circulo social do doente, nomeadamente familiares, vizinhos e outros (BEERY et al., 2002; MALM & HALLBERG, 2006). A equipa de enfermagem do Serviço de Cardiologia do Hospital Fernando Fonseca mantém em funcionamento a consulta de enfermagem ao doente portador de pacemaker e/ou CDI desde há cerca de 18 anos. Nos últimos anos foram sendo realizadas algumas alterações no sentido de melhorar a consulta e os cuidados prestados a estes doentes.

A study of the electrical basis for the inhibition and excitation in autonomically innervated smooth muscle

The aim of this thesis was to investigate the electrical and mechanical responses to inhibitory non-adrenergic noncholinergic (NANC) nerve stimulation in the bovine retractor penis muscle (BRP) and compare them with those to an inhibitory extract made from this muscle. The extract may contain the NANC inhibitory transmitter of the BRP and possibly of other smooth muscles. Because of species differences in the electrical response to NANC nerves in the rat and rabbit anococcygeus the effects of the extract on these tissues was also investigated. Prior to the investigation of the extract, both the excitatory and inhibitory responses to field stimulation in the BRP, and the effects of passive membrane potential displacement were studied using conventional intra- or extracellular (sucrose gap) recording techniques. The majority of cells in the BRP were electrically quiescent independent of the resting tone. The most frequent (in approximately 25% of preparations) form of spontaneous activity, oscillations in membrane potential and tone, may represent a pacemaker activity. The BRP had cable properties; the time constant and space constant indicated a high membrane resistance. In the absence of tone, field stimulation of the BRP evoked excitatory junction potentials (ejps) in every cell impaled and contractions, graded with the strength, frequency and number of pulses; spikes were not observed. Guanethidine (1-3 x 10-5M) abolished the ejps and contractions, confirming their adrenergic origin. Noradrenaline added exogenously depolarised and contracted the muscle. These effects were blocked by the a-adrenoceptor antagonists, phentolamine and prazosin. However, phentolamine (2.5x 10-6M) inhibited the contraction without reducing the ejp significantly. These effects may be independent of adrenoceptor blockade or the ejp may be mediated by a substance other than noradrenaline (e.g. ATP) released from adrenergic nerves. Prazosin (1.4 x lO-6M) failed to block either the ejp or contraction, indicating the possible existence of two types of adrenoceptor in the BRP; one activated by neuronally-released and the other by exogenously-added noradrenaline. ATP, a contaminant in the extract, also depolarised and contracted the BRP. Physostigmine reduced whilst atropine enhanced the ejps and contractions without similarly affecting the response to exogenous noradrenaline. This confirmed the presence of a cholinergic inhibitory innervation acting on the excitatory adrenergic fibres (Klinge and Sjostrand, 1977). TEA (1 x lO-4M) enhanced the ejp and contraction. Higher concentrations (0.5 to 10 x 10-3M) depolarised, increased the tone and evoked electrical and mechanical oscillations but no spikes. The depolarisation and contraction to exogenous noradrenaline were not enhanced, indicating that TEA acts on the adrenergic nerves. Some post-synaptic effect to block K+ channels also seems likely. The relationship between ejp amplitude and membrane potential in the double sucrose gap was linear and indicated a reversal potential more positive than -30mV. Electrotonic pulse amplitude decreased during the ejp, indicating an increased membrane conductance. Ejps and contractions were reduced following the replacement of the NaCl of the Krebs solution with sodium glutamate. This may be due to the effects of glutamate itself (e.g. Ca2+ chelation) rather than reduction in the membrane Cl- gradient. Tone usually developed spontaneously and was accompanied by membrane depolarisation (from -53 to -45mV) which may open voltage-dependent channels, causing Ca2+ entry and/or its release from intracellular binding sites. Field stimulation produced inhibitory potentials (ijps) and relaxations graded with the strength and number of pulses but showing little frequency dependence. Rebound depolarisation and contraction often followed the ijp and relaxation. Tetrodotoxin (3 x IO-6M), but not adrenergic or cholinergic antagonists, abolished the ijp and relaxation, confirming their non-adrenergic non-cholinergic neurogenic nature. The extract, prepared and acid-activated as described by Gillespie, Hunter and Martin (1981), hyperpolarised and relaxed the BRP, as did sodium nitroprusside and adenosine triphosphate (ATP). Unlike the activated extract or sodium nitroprusside, desensitisation to ATP occurred rapidly and without any change in the inhibitory electrical or mechanical responses to field stimulation. The ijp and relaxation in the BRP were insensitive to apamin but abolished by oxyhaemoglobin (4-8 x 10-6M), as were the responses to extract and sodium nitroprusside. In TEA (10-2M), field stimulation evoked relaxations with no accompanying electrical change. The ijp may be unconnected with or additional to another mechanism producing relaxation. The relationship between membrane potential and ijp in the BRP was non-linear. Ijp amplitude was initially increased during membrane potential displacement from -45mV to approximately -60mV. Thereafter (-60 to -l03mV) the ijp was reduced. Ijps were abolished at -27 and -103mV; reversal was not observed. The hyperpolarisation to extract was also enhanced during passive displacement of the membrane potential to more negative values (-57mV). Membrane resistance increased during the ijp. The extract produced inconsistent changes in membrane resistance, possibly because of the presence of more than one active component. K+ withdrawal failed to enhance the ijp or hyperpolarisation to extract and 20mM K+ did not abolish the the ijp at membrane potentials exceeding EK (-49mV). Thus, the ijp or hyperpolarisation to extract are unlikely to be mediated by an increased K+ conductance. Reducing the Cl- abolished the hyperpolarisation to field stimulation and extract. This occurred more quickly than the anticipated reduction in the Cl- gradient and may be due to Ca2+ chelation by the anion substitute (glutamate or benzenesulphonate) or blockade of the resting conductance which is normally inactivated by the transmitter. Ouabain (1-5x 10-5M), which reduces both the Na+ and Cl- gradients, abolished the ijp, implicating either of these ions as the ionic species involved. In the rat and rabbit anococcygeus, field stimulation and extract each reduced guanethidine-induced tone. This was unaccompanied in the majority of cells in the rat by any significant electrical response. In the remaining cells, inhibition of the membrane potential oscillations occurred. The rabbit anococcygeus differed in that inhibition of the electrical oscillations was observed in every cell exhibiting this behaviour. However, the majority of cells in the rabbit were electrically quiescent and showed only small hyperpolarisations to field stimulation and no electrical response to extract. Apamin (1 x 10-7M) failed to block the electrical and mechanical response to field stimulation in the rabbit but did inhibit transiently that to extract. The latter effect may be due to the initial excitatory effects of apamin. The similarities between the electrical effects of the extract and those of inhibitory nerve stimulation in the BRP, rat and rabbit anococcygeus muscles are generally consistent with their being mediated by the same active component. Moreover, the ijp in the BRP shows properties which have not been reported in other non-adrenergic noncholinergically innervated smooth muscles.

Les valves sans suture dans le traitement de la sténose aortique sévère

Rapport présenté en vue de l’obtention du grade de M.Sc.A génie biomédical option génie clinique

Epilepsia refratária e estimulação cerebral profunda : 2 casos de heterotopia subcortical em banda

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Trattamento transcatetere e chirurgico della stenosi valvolare aortica severa in Hesperia Hospital Modena nella seconda decade del ventunesimo secolo

Scopo Confrontare il trattamento transcatetere (TAVI) balloon-expandable con il trattamento chirurgico di sostituzione valvolare aortica (AVR) della stenosi valvolare aortica severa (SVAS) nella pratica clinica real world. Materiali e metodi Nel decennio 2010-2020, 1486 pazienti con SVAS isolata sono stati sottoposti a AVR (n=1049) o TAVI balloon-expandable (n=437) presso Hesperia Hospital Modena. Sono stati analizzati la Mortality nell’intera popolazione e gli episodi di ricovero cardiovascolare nei 5 anni precedenti e durante il follow-up nella popolazione residente in Emilia Romagna (n=1196) al momento della procedura (AVR n=879, TAVI balloon-expandable n=317). Risultati La popolazione TAVI è risultata mediamente più anziana di quella AVR (età media 82.2 vs. 72.7 anni) e maggiormente gravata da comorbidità. L’In-hospital mortality è stata del 1.4% nella AVR e 2.1% nella TAVI (pNS). La sopravvivenza a 5 anni è stata del 85.74% nella AVR e del 59.45% nella TAVI, con la TAVI come fattore predittivo di All-cause mortality (HR 1.44 95%CI 1.14-1.82). La riospedalizzazione per Heart Failure a 5 anni è stata del 20.6% per AVR e 51.3% per TAVI, con dialisi preoperatoria (HR 5.67 95%CI 3.06-10.49) come principale fattore predittivo. Il tasso di All Stroke a 5 anni è stato del 3.7% nella AVR e del 7.5% nella TAVI, con fibrillazione atriale preoperatoria come principale fattore predittivo (HR 1.91 95%CI 1.06-3.45). Il tasso di angioplastica coronarica percutanea (PCI) a 5 anni è stato del 3.1% sia nella AVR che nella TAVI, con previous PCI come principale fattore predittivo (HR 4.86 95%CI 2.57-9.21). L’impianto di pacemaker a 30 giorni è stato del 2.9% nella AVR e 3.4% nella TAVI (pNS). Conclusioni Nella pratica clinica real-world 2010-2020 di un centro cardiochirurgico a medio volume, la TAVI balloon-expandable ha mostrato una eccellente performance a 30 giorni in confronto con la AVR, che invece ha evidenziato una migliore performance durante follow-up.