Clinical update: suspension trauma

Objective.-Suspension trauma refers to the pathophysiologic syndrome that occurs when a victim is suspended motionless in a vertical position for an extended period of time. This can occur in sports that use a harness system as well as in various occupational activities including work on high wires or helicopter rescue operations. We reviewed the scientific evidence published to date in order to improve the prevention and treatment of suspension trauma.Methods.-Medline, PreMedline, the Cochrane Library, and Google Scholar were searched for relevant information about suspension trauma.Results.-Published data describing the pathophysiology of and the therapeutic approach to suspension trauma are sparse and consist mainly of case reports and a limited number of human experimental prospective studies. The pathophysiology of suspension trauma is related to hypovolemia induced by reduced venous return and by vagal stimulation. It is also influenced by the type of harness used. Chest harnesses may induce severe cardiorespiratory repercussions and have the lowest motionless suspension tolerance. Symptoms of suspension trauma include presyncope and can lead to a loss of consciousness.Conclusions.-Sports enthusiasts and workers who use a body harness system should never act alone and should not use a simple chest harness. If a victim shows symptoms of presyncope or is unconscious, he should be released from suspension as soon as is safely possible. There is no clear evidence to support the idea that the return to the horizontal position may contribute to the potential risk of rescue death.

Transverse Cracking Study of Asphalt Pavement, HR-1020, 1981

At a pavement management study meeting in Omaha, Nebraska, September 12 and 13, 1979, the states of Iowa, Kansas and Nebraska agreed on the need for an in-depth engineering study of thermal cracking of bituminous pavement. In addition, the states of Oklahoma and North Dakota agreed to participate in the study. The scope of the study was to analyze all functions relating to the thermal cracking problem to determine how different uses of preventative materials, mix design measures, maintenance repairs, and design of bituminous pavements and overlays might be contributing to the problem and to determine what improvements might be made in these procedures to reduce the problem of thermal cracking. This publication describes the study and its conclusions. One of the conclusions is that the study did not address what the authors believe to be the major contributor to transverse cracking - the subgrade and subbase.

Reconstruction of the recent history of a large deep prealpine lake (Lake Bourget, France) using subfossil chironomids, diatoms, and organic matter analysis: towards the definition of a lake-specific reference state

This paper presents the recent history of a large prealpine lake (Lake Bourget) using chironomids, diatoms and organic matter analysis, and deals with the ability of paleolimnological approach to define an ecological reference state for the lake in the sense of the European Framework Directive. The study at low resolution of subfossil chironomids in a 4-m-long core shows the remarkable stability over the last 2.5 kyrs of the profundal community dominated by a Micropsectra-association until the beginning of the twentieth century, when oxyphilous taxa disappeared. Focusing on this key recent period, a high resolution and multiproxy study of two short cores reveals a progressive evolution of the lake's ecological state. Until AD 1880, Lake Bourget showed low organic matter content in the deep sediments (TOC less than 1%) and a well-oxygenated hypolimnion that allowed the development of a profundal oxyphilous chironomid fauna (Micropsectra-association). Diatom communities were characteristic of oligotrophic conditions. Around AD 1880, a slight increase in the TOC was the first sign of changes in lake conditions. This was followed by a first limited decline in oligotrophic diatom taxa and the disappearance of two oxyphilous chironomid taxa at the beginning of the twentieth century. The 1940s were a major turning point in recent lake history. Diatom assemblages and accumulation of well preserved planktonic organic matter in the sediment provide evidence of strong eutrophication. The absence of profundal chironomid communities reveals permanent hypolimnetic anoxia. From AD 1995 to 2006, the diatom assemblages suggest a reduction in nutrients, and a return to mesotrophic conditions, a result of improved wastewater management. However, no change in hypolimnion benthic conditions has been shown by either the organic matter or the subfossil chironomid profundal community. Our results emphasize the relevance of the paleolimnological approach for the assessment of reference conditions for modern lakes. Before AD 1900, the profundal Micropsectra-association and the Cyclotella dominated diatom community can be considered as the Lake Bourget reference community, which reflects the reference ecological state of the lake.

Newer antiepileptic drugs in the treatment of status epilepticus: Impact on prognosis.

Newer antiepileptic drugs (AEDs) are increasingly prescribed and seem to have a comparable efficacy as the classical AEDs; however, their impact on status epilepticus (SE) prognosis has received little attention. In our prospective SE database (2006-2010), we assessed the use of older versus newer AEDs (levetiracetam, pregabalin, topiramate, lacosamide) over time and its relationship to outcome (return to clinical baseline conditions, new handicap, or death). Newer AEDs were used more often toward the end of the study period (42% of episodes versus 30%). After adjustment for SE etiology, SE severity score, and number of compounds needed to terminate SE, newer AEDs were independently related to a reduced likelihood of return to baseline (p<0.001) but not to increased mortality. These findings seem in line with recent findings on refractory epilepsy. Also, in view of the higher price of the newer AEDs, well-designed, prospective assessments analyzing the impact of newer AEDs on efficacy and tolerability in patients with SE appear mandatory.

Iowa’s Blueprint for Forever Families, 2011

Each year approximately thirty to forty thousand children and youth come to the attention of Iowa’s child welfare and juvenile justice systems and, of those, four to five thousand enter foster care to address child safety or public safety. For most, foster care is a short-term placement designed to allow time to address the reason for removal and to receive the support and services necessary for children to return to their family and community. Unfortunately, too many children and youth remain in foster care too long. Too many youth exit care through emancipation rather than to a permanent family and enduring relationship. Too many young people never realize the security of connections to adults who will be there for a lifetime. When our system fails to find forever families for youth in foster care, long-term outcomes are bleak. A young person’s permanency status is inextricably intertwined with their overall well being.

14.1T magnetic resonance spectroscopic evaluation of metabolic changes in the mouse striatum following transient middle cerebral artery occlusion

Magnetic resonance imaging (MRI) and spectroscopy (MRS) allow establishing theanatomical evolution and neurochemical profiles of ischemic lesions. However onlylimited MRS studies have been reported to-date in mice due to the challenges ofMRS in small organs. The aim of the current work was to study the neurochemicaland imaging sequelae of ischemic stroke in a mouse model in a horizontal bore14.1 Tesla system.ICR-CD1 mice were subjected to 30 minute transient middle cerebral artery occlusion.The extent of the lesion was determined by MRI. The neurochemical profileconsisting of the concentrations of 22 metabolites was measured longitudinallyfollowing the recovery from ischemia at 3, 8 and 24h in the striatum.Our model produced very reproducible striatal lesions which began to appear onT2-weighted images 8h after ischemia. At 24h, they were well established andtheir size correlated with lesions measured by histology. Profound changes couldbe observed in the neurochemical profiles of the core of the striatal lesions as earlyas 3h post-ischemia, in particular, we observed elevated lactate levels, decreases inthe putative neuronal marker N-acetyl-aspartate and in glutamate, and a transienttwo-fold glutamine increase, likely linked to excitotoxic release of glutamate andconversion to glutamine. With further ischemia evolution, other changes appearedat later time-points, mainly decreases of metabolites, consistent with disruption ofcellular function. It is interesting to note that glutamine tended to return to basallevels at 24h.We conclude that early changes in markers of energy metabolism, glutamate excitotoxicityand neuronal viability can be detected with high precision non-invasively inmice following stroke. Such investigations should lead to a better understanding andinsight into the sequential early changes in the brain parenchyma after ischemia,which could be used e.g. for identifying new targets for neuroprotection.

Intermittent atrial tachycardia facilitates atrial fibrillation by a shortening of activation recovery interval

Introduction: We recently observed in a chronic ovine model that a shortening of action potential duration (APD) as assessed by the activation recovery interval (ARI) may be a mechanism whereby pacing-induced atrial tachycardia (PIAT) facilitates atrial fibrillation (AF), mediated by a return to 1:1 atrial capture after the effective refractory period has been reached. The aim of the present study is to evaluate the effect of long term intermittent burst pacing on ARI before induction of AF.Methods: We specifically developed a chronic ovine model of PIAT using two pacemakers (PM) each with a right atrial (RA) lead separated by ∼2cm. The 1st PM (Vitatron T70) was used to record a broadband unipolar RA EGM (800 Hz, 0.4 Hz high pass filter). The 2nd was used to deliver PIAT during electrophysiological protocols at decremental pacing CL (400 beats, from 400 to 110ms) and long term intermittent RA burst pacing to promote electrical remodeling (5s of burst followed by 2s of sinus rhythm) until onset of sustained AF. ARI was defined as the time difference between the peak of the atrial repolarization wave and the first atrial depolarization. The mean ARIs of paired sequences (before and after remodeling), each consisting of 20 beats were compared.Results: As shown in the figure, ARIs (n=4 sheep, 46 recordings) decreased post remodeling compared to baseline (86±19 vs 103±12 ms, p<0.05). There was no difference in atrial structure as assessed by light microscopy between control and remodeled sheep.Conclusions: Using standard pacemaker technology, atrial ARIs as a surrogate of APDs were successfully measured in vivo during the electrical remodeling process leading to AF. The facilitation of AF by PIAT mimicking salvos from pulmonary veins is heralded by a significant shortening of ARI.

Psychiatrie [Psychiatry].

The novelties in clinical psychiatry are close to somatic medicine adaptation. The clinical staging concept in psychiatry (as in cancerology) is the result of an early intervention strategy in psychotic disorders. A differentiated mode of understanding of the phases of psychiatric disorders allows a prevention oriented approach. Individualized therapeutic programmes in accordance with specific problematics favors the orientation towards focalised follow-ups, for instance CBT programmes on Internet may be proposed to patients motivated and rather autonomous. Others, on the contrary, less accessible to health care should benefit of the support of a mobile team and specific coaching to return to vocational services. Systematic follow-up of the metabolic syndrome, often induced by atypical antipsychotics, belongs to those basic adjustment processes.

Recovery of rotators strength after latarjet surgery.

The purposes of this study were to prospectively determine changes in rotator cuff strength before and after surgical shoulder stabilization by Bristow-Latarjet procedure and to better estimate time needed for rotator cuff strength recovery. 20 patients with recurrent anterior posttraumatic shoulder dislocation underwent internal (IR) and external (ER) rotator isokinetic evaluation before and 3, 6 and 21 months after Bristow-Latarjet surgery. In a seated position with 45° of shoulder abduction in the scapular plane, both shoulders were evaluated concentrically with a Con-Trex® isokinetic dynamometer at 180°∙s - 1, 120°∙s - 1 and 60°∙s - 1. 3 months post-surgery, IR and ER strength of the operated shoulder were significantly lower than before surgery ( - 28±20% for IR, - 17±17% for ER) (P<0.05). At 6 and 21 months post-surgery, IR and ER strength were comparable to strength before surgery; strength recovery is seen at 6 months post-surgery with long-term maintenance at 21 months. Given the weakness 3 months post-surgery, return to sports (including overhead and contact sports) should be discussed, and 6 months post-surgery may be a better point for an athlete to resume practicing sports. Isokinetic rotator cuff strength evaluation appears to be relevant in helping to determine the need of continuing strength rehabilitation. Pre-surgical evaluation contributes to the relevance of later comparisons.

Assessment of growth and yield performance of rubber tree clones of the IAC 500 series

The objective of this work was to evaluate the performance of 15 clones of the IAC 500 series of Hevea brasiliensis, developed at Instituto Agronômico (IAC), over a 12-year period, in the northwest region of São Paulo State, Brazil. The 15 new clones evaluated are primary clones obtained from selected ortets within half-sib progenies. The clone RRIM 600, of Malaysian origin, was used as the control. Dry rubber yield performance over a four-year period, mean girth at the tenth year, girth increment before and during tapping, thermal properties of the natural rubber produced and other characters of the laticiferous system were evaluated. Forty percent of the clones were superior in comparison to the control for yield. Clone IAC 500 recorded the highest yield (66.81 g per tree per tapping) over four years of tapping, followed by IAC 502 (62.37 g per tree per tapping), whereas the control recorded 48.71 g per tree per tapping. All selected clones were vigorous in growth. The natural rubber from this IAC clones showed thermal stability up to 300ºC. No differences were observed in the thermal behavior of rubber among the IAC series and the RRIM 600 clones. The clones IAC 500, IAC 501, IAC 502, IAC 503 and IAC 506 are the more promising for small-scale plantations, due to growth and yield potential.

Treatment deviating from guidelines does not influence status epilepticus prognosis.

Status epilepticus (SE) prognosis is related to nonmodifiable factors (age, etiology), but the exact role of drug treatment is unclear. This study was undertaken to address the prognostic role of treatment adherence to guidelines (TAG). We prospectively studied over 26 months a cohort of adults with incident SE (excluding postanoxic). TAG was assessed in terms of drug doses (± 30 % of recommendations) and medication sequence; its prognostic impact on mortality and return to baseline conditions was adjusted for etiology, SE severity [Status Epilepticus Severity Score (STESS)], and comorbidities. Of 225 patients, 26 (12 %) died and 82 (36 %) were discharged with a new handicap; TAG was observed in 142 (63 %). On univariate analysis, age, etiology, SE severity, and comorbidities were significantly related to outcome, while TAG was associated with neither outcome nor likelihood of SE control. Logistic regression for mortality identified etiology [odds ratio (OR) 18.8, 95 % confidence interval (CI) 4.3-82.8] and SE severity (STESS ≥ 3; OR 1.7, 95 % CI 1.2-2.4) as independent predictors, and for lack of return to baseline, again etiology (OR 7.4, 95 % CI 3.9-14.0) and STESS ≥ 3 (OR 1.7, 95 % CI 1.4-2.2). Similar results were found for the subgroup of 116 patients with generalized-convulsive SE. Receiver operator characteristic (ROC) analyses confirmed that TAG did not improve outcome prediction. This study of a large SE cohort suggests that treatment adherence to recommendations using current medications seems to play a negligible prognostic role (class III), confirming the importance of the biological background. Awaiting further treatment trials, it appears mandatory to apply resources towards identification of new therapeutic approaches.

Vaneri- ja kertopuutehtaiden kuivatuskoneiden lämmöntalteenottojen järjestelmäselvitys

Vanerin tai kertopuun valmistusprosessissaviilun kuivaukseen käytetään suurin osa koko valmistusprosessin primäärienergiasta. Viilunkuivauskoneessa viilun sisältämä vesi siirretään tyypillisesti prosessihöyryllä lämmitettyyn viilunkuivaajan kiertoilmaan höyrystämällä ja poistetaanviilunkuivaajasta poistoilman mukana. Viilunkuivaajan poistoilma on lämmintä jaerittäin suuren kosteuspitoisuutensa takia sisältää runsaasti energiaa. Tyypillisellä viilunkuivaajalla poistoilmaan sitoutunut lämpöteho vaihtelee prosessiolosuhteista riippuen välillä 2,7-5,7 MW. Diplomityössä tutkittiin viilunkuivaajan poistoilman sisältämän lämmön talteenottoa laitteistolla, johon kuuluu lämmöntalteenottopesuri, jossa poistoilmalla lämmitetään tuotantolaitoksen tukkipuun hautomon kiertovettä sekä ilma-ilma-lämmönsiirrin, jolla lämmitetään pesurista poistuvan ilman jäännöslämmöllä ulkoilmaa tehdassalin tuloilmakäyttöön. Työn tavoitteena oli kehittää lämmöntalteenottojärjestelmän suunnittelua, mitoitusta ja ajotapoja. Työssä analysoitiin teoreettisesti pesuria ja ilmalämmönsiirrintä, kehitettiin lämmöntalteenottopesurin simulointimenetelmä ja mitattiin toiminnassa olevia talteenottolaitteistoja. Tutkimuksessa todettiin lämmöntalteenottohyötysuhteen vaihtelevan lämmityskaudella välillä 50-70 %. Lämmöntalteenottolaitteiston pesurin veteen saatava teho riippuu ensisijaisesti viilunkuivaajan poistoilman lämpösisällöstä, joka on enimmäkseen kosteusriippuvainen ja ilmanvaihtoilmaan saatava teho ulkolämpö-tilan määräämästä tehontarpeesta. Pesurin vesijärjestelmän vaikutusmekanismit pesurin suorituskykyyn tunnistettiin ja niiden pohjalta annetaan suositukset mitoitukseen ja ajotapaan. Lämmöntalteenottolaitteiston lämpötehon tasapainottamiseen pesurin ja ilma-ilma-lämmönsiirtimen välillä mitoituksen avulla esitellään työkalut.

Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation

The Permian Chert Event (PCE) was a 30 Ma long episode of unusual chert accumulation along the northwest margin of Pangea, and possibly worldwide. The onset of the PCE occurred at about the Sakmarian-Artinskian boundary in the Sverdrup Basin, Canadian Arctic, where it coincides with a maximum flooding event, the ending of high-frequency/high-amplitude shelf cyclicity, the onset of massive biogenic chert deposition in deep-water distal areas, and a long-term shift from warm- to cool-water carbonate sedimentation in shallow-water proximal areas. A similar and coeval shift is observed from the Barents Sea to the northwestern USA. A landward and southward expansion of silica factories occurred during the Middle and Late Permian at which time warm-water carbonate producers disappeared completely from the northwest margin of Pangea. Biotically impoverished and increasingly narrow cold-water carbonate factories (characterised by non-cemented bioclasts of sponges, bryozoans, echinoderms and brachiopods) were then progressively replaced by silica factories. By Late Permian time, little carbonate sediments accumulated in the Barents Sea and in the Sverdrup Basin. where the deep- to shallow-water sedimentary spectrum was occupied by siliceous sponge spicules. By that time, biogenic silica sedimentation was common throughout the world. Silica factories collapsed in the Late Permian, abruptly bringing the PCE to an end. In northwest Pangea, the end- Permian collapse of the PCE was associated with a major transgression and with a return to much warmer oceanic and continental climatic conditions. Chert deposition resumed in the distal oceanic areas during the early Middle Triassic (Anisian) after a 8-10 Ma interruption (Early Triassic Chert Gap). The conditions necessary for the onset, expansion and zenith of the PCE were provided by the thermohaline circulation of nutrient-rich cold waters along the northwestern and western margin of Pangea, and possibly throughout the world oceans. These conditions provided an efficient transportation mechanism that constantly replenished the supply of silica in the area, created a nutrient- and oxygen-rich environment favouring siliceous biogenic productivity. established cold sea-floor conditions, hindering silica dissolution, while increasing calcium carbonate solubility, and provided conditions adverse to organic and inorganic carbonate production, The northwest margin of Pangea was, for nearly 30 Ma. bathed by cold waters presumably derived from the seasonal melting of northern sea ice, the assumed engine for thermohaline circulation. This process started near the Sakmarian-Artinskian boundary. intensified throughout Middle and Late Permian time and ceased suddenly in latest Permian time, It led to oceanic conditions much colder than normally expected from the palaeolatitudes. and the influence of cold northerly-derived water was felt as far south southern Nevada. The demise of silica factories was caused by the rapid breakdown of these conditions and the establishment of a much warmer marine environment accompanied by sluggish circulation and perhaps a reduced input of dissolved silica to the ocean. Complete thawing of northern sea ice would have ended thermohaline circulation and led to warm and sluggish oceanic conditions inimical to the production. accumulation and preservation of biogenic silica.

Four-corner bone arthrodesis with dorsal rectangular plate: series and personal technique.

Controversy exists about the best method to achieve bone fusion in four-corner arthrodesis. Thirty-five patients who underwent this procedure by our technique were included in the study. Surgical indications were stage II-III SLAC wrist, stage II SNAC wrist and severe traumatic midcarpal joint injury. Mean follow-up was 4.6 years. Mean active flexion and extension were 34 degrees and 30 degrees respectively; grip strength recovery was 79%. Radiological consolidation was achieved in all cases. The mean DASH score was 23 and the postoperative pain improvement by visual analogue scale was statistically significant. Return to work was possible at 4 months for the average patient. Complications were a capitate fracture in one patient and the need for hardware removal in four cases. Four-corner bone wrist arthrodesis by dorsal rectangular plating achieves an acceptable preservation of range of motion with good pain relief, an excellent consolidation rate and minimal complications.

Growth mechanisms and timing of emplacement of a vertically layered mafic intrusion in the feeder zone of an ocean island volcano (Fuerteventura, Canary islands)

Résumé pour le grand public L'île de Fuerteventura (Canaries) offre l'occasion rare d'observer les racines d'un volcan océanique édifié il y a 25 à 30 millions d'années et complètement érodé. On y voit de nombreux petits plutons de forme et composition variées, témoignant d'autant d'épisodes de l'activité magmatique. L'un de ces plutons, appelé PX1, présente une structure inhabituelle formée d'une alternance de bandes verticales d'épaisseur métrique à hectométrique de roches sombres de composition pyroxénilique ou gabbroïque. Les pyroxénites résultent clairement de l'accumulation de cristaux de pyroxènes et non de la simple solidification d'un magma? Se pose dès lors la question de la nature du processus qui a conduit à l'accumulation verticale de niveaux concentrés en pyroxènes. En effet, les litages pyroxénitiques classiques sont subhorizontaux, car ils résultent de l'accumulation gravitaire des cristaux séparés du magma dont ils cristalli¬sent par sédimentation. Cette étude vise à identifier et comprendre les mécanismes qui ont engendré ce Iitage minéralogique vertical et l'im¬portant volume de ces faciès cumulatifs. Nous nous sommes également intéressés aux conditions de pression et de température régnant au moment de la mise en place du pluton, ainsi qu'à sa durée de vie et à sa vitesse de refroidis¬sement. Enfin une approche géochimique nous a permis de préciser la nature de la source mantellique des magmas liés à cette activité magmatique. PX1 est en réalité un complexe filonien formé à des conditions de pression et de température de 1-2 kbar et 1050- 1100°C; sa construction a nécessité au moins 150 km3 de magma. L'alternance d'horizons gabbroïques et pyroxéniti¬ques représente des injections successives de magma sous la forme de filons verticaux, mis en place dans un contexte régional en extension. L'étude des orientations des minéraux dans ces faciès révèle que les horizons gabbroïques enregistrent l'extension régionale, alors que les pyroxénites sont générées par une compaction au sein du pluton. Ceci suggère que le régime des contraintes, qui était extensif lors de l'initiation de la mise en place de PX1, est pério¬diquement devenu compressif au sein même du pluton. Cette compression serait liée à des cycles de mise en place où la vitesse de croissance du pluton dépassait celle de l'extension régionale. La différenciation observée au sein de chaque horizon, depuis des pyroxénites riches en olivine jusqu'à des pyroxé¬nites à plagioclase interstitiel et des gabbros, ainsi que la composition géochimique des minéraux qui les constituent suggèrent que chaque filon vertical s'est mis en place à partir d'un magma de composition identique, puis a évolué indépendamment des autres en fonction du régime thermique et du régime des contraintes local. Lorsque le magma en train de cristalliser s'est trouvé en compression, le liquide résiduel a été séparé des cristaux déjà formés et extrait du système, laissant derrière lui une accumulation de cristaux dont la nature et les proportions dépendaient du stade de cristallisation atteint par le magma au moment de l'extraction. Ainsi, les niveaux de pyroxénites à olivine (premier minéral à cristalliser) ont été formés lorsque le magma correspondant était encore peu cristallisé; à l'inverse, les py¬roxénites riches en plagioclase (minéral plus tardif dans la séquence de cristallisation) et certains gabbros à caractère cumulatif résultent d'une compression tardive dans le processus de cristallisation du filon concerné. Les liquides résiduels extraits des niveaux pyroxénitiques sont rarement observés dans PX1, certaines poches et filonets de com¬position anorthositique pourraient en être les témoins. L'essentiel de ces liquides a probablement gagné des niveaux supérieurs du pluton, voire la surface du volcan. L'origine du régime compressif périodique affectant les filons en voie de cristallisation est attribuée aux injections suivantes de magma au sein du pluton, qui se sont succédées à un rythme plus rapide que la vitesse de consolidation des filons. Des datations U/Pb de haute précision sur des cristaux de zircon et de baddeleyite ainsi que40Ar/39Ar sur des cris¬taux d'amphibole révèlent une initiation de la mise en place de PX1 il y a 22.1 ± 0,7 Ma; celle-ci a duré quelque 0,48 ± 0,22 à 0,52 ± 0,29 Ma. Ce laps de temps est compatible avec celui nécessaire à la cristallisation des filons individuels, qui va de moins d'une année lors de l'initiation du magmatisme à 5 ans lors du maximum d'activité de PX1. La présence de cristaux résorbés enregistrant une cristallisation complexe suggère l'existence d'une chambre mag¬matique convective sous-jacente à PX1 et périodiquement rechargée. Les compositions isotopiques des roches étu¬diées révèlent une source mantellique profonde de type point chaud avec une contribution du manteau lithosphéri- que métasomatisé présent sous les îles Canaries. Résumé L'intrusion mafique Miocène PX1 fait partie du soubassement superficiel (0.15-0.2 GPa, 1100 °Q d'un volcan d'île océanique. La particularité de ce pluton est l'existence d'alternances d'unités de gabbros et de pyroxénites qui met¬tent en évidence un litage magmatique vertical (NNE-SSW). Les horizons gabbroiques et pyroxénitiques sont constitués d'unités de différenciation métriques qui suggèrent tine mise en place par injections périodiques de filons verticaux de magma formant un complexe filonien. Chaque filon vertical a subi une différenciation parallèle à un front de solidification sub-vertical parallèle aux bords du filon. Les pyroxénites résultent du fractionnement et de l'accumulation d'olivine ± clinopyroxene ± plagioclase à partir d'un magma basaltique faiblement alcalin et sont interprétées comme étant des imités de différenciation tronquées dont le liquide interstitiel a été extrait par compaction. L'orientation préférentielle des clinopyroxènes dans ces pyroxe- nites (obtenues par analyse EBSD et micro-tomographique) révèle une composante de cisaillement simple dans la genèse de ces roches, ce qui confirme cette interprétation. La compaction des pyroxénites est probablement causée par a mise en place de filons de magma suivants. Le liquide interstitiel expulsé est probablement par ces derniers. Les clinopyroxènes des gabbros, montrent une composante de cisaillement pure suggérant qu'ils sont affectés par une déformation syn-magmatique parallèle aux zones de cisaillement NNE-SSW observées autour de PX1 et liées au contexte tectonique Miocène d'extension régionale. Ceci suggère que les gabbros sont liés à des taux de mise en place faibles à la fin de cycles d'activité magmatique et sont peu ou pas affectés par la compaction. L'initiation et la géométrie de PX1 sont donc contrôlées par le contexte tectonique régional d'extension alors que les taux et les volumes de magma dépendent de facteurs liés à la source. Des taux d'injection élevés résultent probable¬ment en une croissance du pluton supérieure à la place crée par cette extension. Dans ce cas de figure, la propagation des nouveaux dykes et l'inaptitude du magma à circuler à travers les anciens dykes cristallisés pourrait causer une augmentation de la pression non-lithostatique sur ces derniers, exprimée par un cisaillement simple et l'expulsion du liquide interstitiel qu'ils contiennent (documenté par les zones de collecte anorthositiques). Les compositions en éléments majeurs et traces des gabbros et pyroxenites de PX1 sont globalement homogènes et dépendent de la nature cumulative des échantillons. Cependant, de petites variations des concentrations en éléments traces ainsi que les teneurs en éléments traces des bordures de clinopyroxenes suggèrent que ces derniers ont subi un processus de rééquilibrage et de cristallisation in situ. L'homogénéité des compositions chimiques des échantillons, ainsi que la présence de grains de clinopyroxene résorbés suggère que le complexe filonien PX1 s'est mis en place au dessus d'une chambre magmatique périodiquement rechargée dans laquelle la convection est efficace. Chaque filon est donc issu d'un même magma, mais a subi une différenciation par cristallisation in situ (jusqu'à 70% de fraction¬nement) indépendamment des autres. Dans ces filons cristallisés, les minéraux cumulatifs subissent un rééquilibrage partiel avec les liquide interstitiel avant que ce dernier ne soit expulsé lors de la compaction (mettant ainsi un terme à la différenciation). Ce modèle de mise en place signifie qu'un minimum de 150Km3 de magma est nécessaire à la genèse de PX1, une partie de ce volume ayant été émis par le 'Central Volcanic Complex' de Fuerteventura. Les rapports isotopiques radiogéniques mesurés révèlent la contribution de trois pôles mantelliques dans la genèse du magma formant PX1. Le mélange de ces pôles HIMU, DMM et EM1 refléterai l'interaction du point chaud Cana¬rien avec un manteau lithosphérique hétérogène métasomatisé. Les petites variations de ces rapports et des teneurs en éléments traces au sein des faciès pourrait refléter des taux de fusion partielle variable de la source, résultant en un échantillonnage variable du manteau lithosphérique métasomatisé lors de son interaction avec le point chaud. Des datations U/Pb de haute précision (TIMS) sur des cristaux de zircon et de baddeleyite extraits de gabbros de PX1 révèlent que l'initiation de la cristallisation du magma a eu lieu il y a 22.10±0.07 Ma et que l'activité magmatique a duré un minimum de 0.48 à 0.52 Ma. Des âges 40Ar/39Ar obtenus sur amphibole sont de 21.9 ± 0.6 à 21.8 ± 0.3 Ma, identiques aux âges U/Pb. La combinaison de ces méthodes de datations, suggère que le temps maximum nécessaire à PX1 pour se refroidir en dessous de la température de fermeture de l'amphibole est de 0.8Ma. Ceci signifie que la durée de vie de PX1 est de 520 000 à 800 000 ans. La coexistence de cristaux de baddeleyite et de zircon dans un gabbro est attribuée à son interaction avec un fluide riche en C02 relâché par les carbonatites encaissantes lors du métamorphisme de contact généré par la mise en place de PX1 environ 160 000 ans après le début de sa mise en place. Les durées de vie obtenue sont en accord avec le modèle de mise en place suggérant une durée de cristallisation poux chaque filon allant de 1 an à 5 ans. Abstract The Miocene PX1 gabbro-pyroxenite intrusion (Fuerteventura, Canary Islands), is interpreted as the shallow-level feeder-zone (0.15-0.2 GPa and 1100-1120°C), to an ocean island volcano. The particularity of PX1 is that it displays a NNE-SSW trending vertical magmatic banding expressed by alternating gabbro and pyroxeriite sequences. The gabbro and pyroxenite sequences consist of metre-thick differentiation units, which suggest emplacement by pe¬riodic injection of magma pulses as vertical dykes that amalgamated, similarly to a sub-volcanic sheeted dyke com¬plex. Individual dykes underwent internal differentiation following a solidification front (favoured by a significant lateral/horizontal thermal gradient) parallel to the dyke edges. Pyroxenitic layers result from the fractionation and accumulation of clinopyroxene ± olivine ± plagioclase crystals from a mildly alkaline basaltic liquid and are interpre¬ted as truncated differentiation sequences, from which residual melts were extracted by compaction. Clinopyroxene mineral orientation in pyroxenites (evidenced by EBSD and micro X-ray tomography analysis) display a marked pure shear component, supporting this interpretation. Compaction and squeezing of the crystal mush is ascribed to the incoming and inflating magma pulses. The resulting expelled interstitial liquid was likely collected and erupted along with the magma flowing through the newly injected dykes. Gabbro sequences represent crystallised coalesced magma batches, emplaced at lower rates at the end of eruptive cycles, and underwent minor melt extraction as evi¬denced by clinopyroxene orientations that record a simple shear component suggesting syn-magmatic deformation parallel to observed NNF.-SSW trending shear-zones induced by the regional tensional Miocene stress-field. The initiation and geometry of PX1 is controlled by the regional extensional tectonic regime whereas rates and vo¬lumes of magma depend on source-related factors. High injection rates are likely to induce intrusion growth rates larger than could be accommodated by the regional extension. In this case, dyke tip geometry and the inability of magma to circulate through previously emplaced and crystallised dykes could result in an increase of non-lithostatic pressure on previously emplaced mushy dyke walls; generating strong pure-shear compaction and interstitial melt expulsion within the feeder-zone as recorded by the cumulitic pyroxenite bands and anorthositic collection zones. The whole-rock major and trace-element chemistry of PX1 gabbros and pyroxenites is globally homogeneous and controlled by the cumulate nature of the samples (i.e. on the modal proportions of olivine, pyroxene, plagioclase and oxides). However, small variations of whole-rock trace-element contents as well as trace-element contents of clinopyroxene rims suggest that in-situ re-equilibration and crystallisation has occurred. Additionally, the global homogeneity and presence of complex zoning of rare resorbed clinopyroxene crystals suggest that the PX1 feeder- zone overlies a periodically replenished and efficiently mixed magma chamber. Each individual dyke of magma thus originated from a compositionally constant mildly alkaline magma and differentiated independently from the others reaching up to 70% fractionation. Following dyke arrest these are affected by interaction with the trapped interstitial liquid prior to its compaction-linked expulsion (thus stopping the differentiation process). This emplacement model implies that minimum amount of approximately 150 km3 of magma is needed to generate PX1, part of it having been erupted through the overlying Central Volcanic Complex of Fuerteventura. The radiogenic isotope ratios of PX1 samples reveal the contribution on three end-members during magma genesis. This mixing of the H1MU, EMI and DMM end-members could reflect the interaction of the deep-seated Canarian mantle plume with a heterogeneous metasomatic and sepentininsed lithospheric mantle. Additionally, the observed trace-element and isotopic variations within the same fades groups could reflect varying degrees of partial melting of the source region, thus tapping more or less large areas of the metasomatised lithospheric mantle during interac¬tion with the plume. High precision ID-TIMS U/Pb zircon and baddeleyite ages from the PX1 gabbro samples, indicate initiation of magma crystallisation at 22.10 ± 0.07 Ma. The magmatic activity lasted a minimum of 0.48 to 0.52 Ma. 40Ar/39Ar amphibole ages are of 21.9 ± 0.6 to 21.8 ± 0.3, identical within errors to the U/Pb ages. The combination of the 40Ar/39Ar and U/Pb datasets imply that the maximum amount of time PX1 took to cool below amphibole Tc is 0.8 Ma, suggesting PX1 lifetime of 520 000 to 800 000 years. On top of this, the coexistence of baddeleyite and zircon in a single sample is ascribed to the interaction of PX1 with C02-rich carbonatite-derived fluids released from the host-rock carbonatites during contact metamorphism 160 000 years after PX1 initiation. These ages are in agreement with the emplacement model, implying a crystallisation time of less than 1 to 5 years for individual dykes.