Plate tectonics of the Altaids

Abstract: The Altaids consist in a huge accretionary-type belt extending from Siberia through Mon-golia, northern China, Kyrgyzstan and Kazakhstan. They were formed from the Vendian through the Jurassic by the accretion of numerous displaced and exotic terranes (e.g. island arc, ribbon microcontinent, seamount, basaltic plateau, back-arc basin). The number, nature and origin of the terranes differ according to the palaeotectonic models of the different authors. Thanks to a geo- dynamic study (i.e. definition of tectonic settings and elaboration of geodynamic scenarios) and plate tectonics modelling, this work aims to present an alternative model explaining the Palaeozoic palaeotectonic evolution of the Altaids. Based on a large set of compiled geological data related to palaeogeography and geodyna¬mic (e.g. sedimentology, stratigraphy, palaeobiogeography, palaeomagnetism, magmatism, me- tamorphism, tectonic...), a partly new classification of the terranes and sutures implicated in the formation of the Altaids is proposed. In the aim to elaborate plate tectonics reconstructions, it is necessary to fragment the present arrangement of continents into consistent geological units. To avoid confusion with existing terminology (e.g. tectonic units, tectono-stratigraphic units, micro- continents, terranes, blocks...), the new concept of "Geodynamic Units (GDU)" was introduced. A terrane may be formed by a set of GDUs. It consists of a continental and/or oceanic fragment which has its own kinematic and geodynamic evolution for a given period. With the same ap-proach, the life span and type of the disappeared oceans is inferred thanks to the study of the mate-rial contained in suture zones. The interpretation of the tectonic settings within the GDUs comple-ted by the restoration of oceans leads to the elaboration of geodynamic scenarios. Since the Wilson cycle was presented in 1967, numerous works demonstrated that the continental growth is more complex and results from diverse geodynamic scenarios. The identification of these scenarios and their exploitation enable to elaborate plate tectonics models. The models are self-constraining (i.e. space and time constraints) and contest or confirm in turn the geodynamic scenarios which were initially proposed. The Altaids can be divided into three domains: (1) the Peri-Siberian, (2) the Kazakhstan, and (3) the Tarim-North China domains. The Peri-Siberian Domain consists of displaced (i.e. Sayan Terrane Tuva-Mongolian, Lake-Khamsara Terrane) and exotic terranes (i.e. Altai-Mongolian and Khangai-Argunsky Terrane) accreted to Siberia from the Vendian through the Ordovician. Fol-lowing the accretion of these terranes, the newly formed Siberia active margin remained active un-til its part collision with the Kazakhstan Superterrane in the Carboniferous. The eastern part of the active margin (i.e. East Mongolia) continued to act until the Permian when the North-China Tarim Superterrane collided with it. The geodynamic evolution of the eastern part of the Peri-Siberian Domain (i.e. Eastern Mongolia and Siberia) is complicated by the opening of the Mongol-Okhotsk Ocean in the Silurian. The Kazakhstan Domain is composed of several continental terranes of East Gondwana origin amalgamated together during the Ordovician-Silurian time. After these different orogenic events, the Kazakhstan Superterrane evolved as a single superterrane until its collision with a Tarim-North China related-terrane (i.e. Tianshan-Hanshan Terrane) and Siberian Continent during the Devonian. This new organisation of the continents imply a continued active margin from Siberia, to North China through the Kazakhstan Superterrane and the closure of the Junggar- Balkash Ocean which implied the oroclinal bending of the Kazakhstan Superterrane during the entire Carboniferous. The formation history of the Tarim-North China Domain is less complex. The Cambrian northern passive margin became active in the Ordovician. In the Silurian, the South Tianshan back-arc Ocean was open and led to the formation of the Tianshan-Hanshan Terrane which collided with the Kazakhstan Superterrane during the Devonian. The collision between Siberia and the eastern part of the Tarim-North China continents (i.e. Inner Mongolia), implied by the closure of the Solonker Ocean, took place in the Permian. Since this time, the major part of the Altaids was formed, the Mongol-Okhotsk Ocean only was still open and closed during the Jurassic. Résumé: La chaîne des Altaïdes est une importante chaîne d'accrétion qui s'étend en Sibérie, Mon-golie, Chine du Nord, Kirghizstan et Kazakhstan. Elle s'est formée durant la période du Vendian au Jurassique par l'accrétion de nombreux terranes déplacés ou exotiques (par exemple arc océa-nique, microcontinent, guyot, plateau basaltique, basin d'arrière-arc...). Le nombre, la nature ou encore l'origine diffèrent selon les modèles paléo-tectoniques proposés par les différents auteurs. Grâce à une étude géodynamique (c'est-à-dire définition des environnements tectoniques et éla-boration de scénarios géodynamiques) et à la modélisation de la tectonique des plaques, ce travail propose un modèle alternatif expliquant l'évolution paléo-tectonique des Altaïdes. Basé sur une large compilation de données géologiques pertinentes en termes de paléo-géographie et de géodynamique (par exemple sédimentologie, stratigraphie, paléo-biogéographie, paléomagnétisme, magmatisme, métamorphisme, tectonique...), une nouvelle classification des terranes et des sutures impliqués dans la formation des Altaïdes est proposée. Dans le but d'élabo¬rer des reconstructions de plaques tectoniques, il est nécessaire de fragmenter l'arrangement actuel des continents en unités tectoniques cohérentes. Afin d'éviter les confusions avec la terminolo¬gie existante (par exemple unité tectonique, unité tectono-stratigraphique, microcontinent, block, terrane...), le nouveau concept d' "Unité Géodynamique (UGD)" a été introduit. Un terrane est formé d'une ou plusieurs UGD et représente un fragment océanique ou continental défini pas sa propre cinétique et évolution géodynamique pour une période donnée. Parallèlement, la durée de vie et le type des océans disparus (c'est-à-dire principal ou secondaire) est déduite grâce à l'étude du matériel contenu dans les zones de sutures. L'interprétation des environnements tectoniques des UGD associés à la restauration des océans mène à l'élaboration de scénarios géodynamiques. Depuis que le Cycle de Wilson a été présenté en 1967, de nombreux travaux ont démontré que la croissance continentale peut résulter de divers scénarios géodynamiques. L'identification et l'ex-ploitation de ces scénarios permet finalement l'élaboration de modèles de tectonique des plaques. Les modèles sont auto-contraignants (c'est-à-dire contraintes spatiales et temporelles) et peuvent soit contester ou confirmer les scénarios géodynamiques initialement proposés. Les Altaïdes peuvent être divisées en trois domaines : (1) le Domaine Péri-Sibérien, (2) le Domaine Kazakh, et (3) le Domaine Tarim-Nord Chinois. Le Domaine Péri-Sibérien est composé de terranes déplacés (c'est-à-dire Terrane du Sayan, Tuva-Mongol et Lake-Khamsara) et exotiques (c'est-à-dire Terrane Altai-Mongol et Khangai-Argunsky) qui ont été accrétés au craton Sibérien durant la période du Vendien à l'Ordovicien. Suite à l'accrétion de ces terranes, la marge sud-est de la Sibérie nouvellement formée reste active jusqu'à sa collision partielle avec le Superterrane Ka-zakh au Carbonifère. La partie est de la marge active (c'est-à-dire Mongolie de l'est) continue son activité jusqu'au Permien lors de sa collision avec le Superterrane Tarim-Nord Chinois. L'évolu¬tion géodynamique de la partie est du Domaine Sibérien est compliquée par l'ouverture Silurienne de l'Océan Mongol-Okhotsk qui disparaîtra seulement au Jurassique. Le Domaine Kazakh est composé de plusieurs terranes d'origine est-Gondwanienne accrétés les uns avec les autres avant ou pendant le Silurien inférieur et leurs evolution successive sous la forme d'un seul superterrane. Le Superterrane Kazakh collisione avec un terrane Tarim-Nord Chinois (c'est-à-dire Terrane du Tianshan-Hanshan) durant le Dévonien et le continent Sibérien au Dévonien supérieur. Ce nouvel agencement des plaques induit une marge active continue le long des continents Sibérien, Kazakh et Nord Chinois et la fermeture de l'Océan Junggar-Balkash qui provoque le plissement oroclinal du Superterrane Kazakh durant le Carbonifère. L'histoire de la formation du Domaine Tarim-Nord Chinois est moins complexe. La marge passive nord Cambrienne devient active à l'Ordovicien et l'ouverture Silurienne du bassin d'arrière-arc du Tianshan sud mène à la formation du terrane du Tianshan-Hanshan. La collision Dévonienne entre ce dernier et le Superterrane Kazakh provoque la fermerture de l'Océan Tianshan sud. Finalement, la collision entre la Sibérie et la partie est du continent Tarim-Nord Chinois (c'est-à-dire Mongolie Intérieure) prend place durant le Permien suite à la fermeture de l'Océan Solonker. La majeure partie des Altaïdes est alors formée, seul l'Océan Mongol-Okhotsk est encore ouvert. Ce dernier se fermera seulement au Jurassique.

A generalization of Cope's rule

For numerous shelly invertebrates, Cope's rule is shown in this paper to merely describe the particular case where volume increase is strictly coupled with diameter or length. Allometries, which are frequently observed in the evolution of the shells' geometry, mean that their size, volume and surface can vary independently. The consequences of this can be summarized as follows : 1) volume increase not coupled with an increase of diameter or length of the organisms generates increasing involution and/or lateral width in the shell of cephalopods, foraminifera and radiolarians; 2) an increase of the biomineralizing surface, not coupled with volume increase, generates increasing apparent complexity in the sutures and growth lines in ammonites, and an increase in the complexity and number of chambers in foraminifera.

Laparoscopic Pancreatic Enucleation With End-to-End Pancreatic Duct Reconstruction.

BACKGROUND: Laparoscopic enucleation for neuroendocrine pancreatic tumors has become a feasible technique, with a reported incidence of pancreatic fistula ranging from 13 to 29 %.1 (-) 3 This report describes the first successful case of laparoscopic pancreatic enucleation with resection of the main pancreatic duct followed by end-to-end anastomosis. METHODS: A 41-year-old woman was admitted to the authors' hospital for repeated syncope. Hypoglycemia also was noted. A contrast-enhanced computed tomography examination showed a highly enhanced tumor measuring 22 mm in diameter on the ventral side of the pancreatic body adjacent to the main pancreatic duct. The patient's blood insulin level was elevated, and her diagnosis was determined to be pancreatic insulinoma. Laparoscopic pancreatic enucleation was performed. Approximately 2 cm of the main pancreatic duct was segmentally resected, and a short stent (Silicone tube: Silastic, Dow Corning Corporation, Midland, MI) was inserted. The direct anastomosis of the main pancreatic duct was performed using four separate sutures with an absorbable monofilament (6-0 PDS). RESULTS: The operation time was 166 min, and the estimated blood loss was 100 mL. The postoperative course was uneventful, and the patient was discharged from hospital on postoperative day 7. The pathologic findings showed a well-differentiated insulinoma and a negative surgical margin. A computed tomography examination performed 1 month after the operation showed a successful anastomosis with a patent main pancreatic duct. CONCLUSIONS: Laparoscopic segmental resection of the main pancreatic duct and end-to-end anastomosis can be performed safely with the insertion of a short stent. This technique also can be used for a central pancreatectomy.

Adjustable Suture Removal: Increasing Aqueous Flow in "Safe" Trabeculectomy.

Purpose: Aqueous flow through trabeculectomy blebs has been suggested to influence filtration bleb survival. We investigated the relationship between the requirement to increase aqueous flow via adjustable suture removal and surgical outcomes following "safe trabeculectomy" with mitomycin C (MMC). Methods: 62 consecutive eyes of 53 patients underwent fornix based trabeculectomy with adjustable sutures, intraoperative MMC and intensive postoperative steroids. Subconjunctival antimetabolite injections and bleb needlings were administered according to bleb vascularity and IOP trends. Main outcome measures were: success rates (definition: IOP≤21mmHg and 20% IOP reduction); number of antimetabolite injections; bleb needlings; number of of eyes recommencing glaucoma medications and complications. Results: Mean age was 70.4±16.0 years (mean± SD); mean preoperative IOP was 24.5±9.1 mmHg and decreased to 12.3±8.9mmHg postoperatively. Mean number of sutures was 2.6 ± 0.7. Eyes were divided into 2 groups in relation to the number of sutures removed. The number of subconjunctival MMC injections required for those requiring 2 suture removals was significantly greater than those requiring 1 suture removal (p<0.05) The number of needlings and 5FU injections also increased but did not reach significance (p=0.09 and p=0.34 respectively). Least-squared linear regression analysis showed the number of needlings required had a statistically significant (p=0.05) trend with respect to time elapsed between surgery and first suture removal. No other interventions had significant trends. Mean time between surgery and suture removal was: 4.2±9.2 weeks (suture #1) and 5.7±9.7 weeks (suture#2). Antiglaucoma medication was restarted in only 5 eyes. Postoperative complications were infrequent: Seidel (3.2%), peripheral choroidal effusions at any time (3.2%), and shallow anterior chamber (1.6%). Conclusion: Eyes requiring a greater number of suture removals required a significantly greater number of antifibrosis interventions. The time elapsed before suture removal was inversely related to the number of postoperative needlings, suggesting these eyes may have decreased aqueous production and therefore require aggressive post-operative management to prevent bleb failure.

May absorbable suture anchors increase the rate of recurrent dislocations after shoulder stabilization?

Introduction: Absorbable anchors are frequently used in shoulder surgery. Mechanisms of absorption induce a local inflammatory reaction. It is not clear if this process may disturb healing of the capsule and ligaments. The purpose of the study was to compare the rate of recurrent dislocation following open shoulder stabilization when using absorbable or non-absorbable suture anchors. Methods: Between 1999 and 2003, 83 open Bankart repairs were performed by the same surgeon. All patients had recurrent traumatic anterior shoulder instability. All had preoperative arthro-MRI or arthro-CT which did not reveal any significant bony Bankart lesion or rotatorcuff tear. Thirty-four patients were treated with absorbable anchors (Panalok®) and sutures (Panacryl®) and 49 with non-absorbable anchors (Mitek GII®) and sutures (Ethibond®). The same surgical technique and rehabilitation protocol were used. The incidence of sports ability and recurrent instability were recorded. We defined instability as true dislocation. Results: Five patients on 34 were lost to follow-up in the absorbable group and 7 on 49 in the non-absorbable group. The mean age of absorbable group was 25 years (range, 17-39 years). At a mean follow-up of 66 months (range, 54-76 months), 86% could resume sports activity. Five patients on 29 (17%) reported recurrent instability and two did need revision surgery. The mean age in non-absorbable group was 28 year (range, 18-47 years). At a mean follow-up of 78 months (range, 49-82 months), 93% could resume sports activity. Three patients on 42 (7%) reported recurrent instability and one did need revision surgery. Conclusion: This clinical study showed a clear tendency to a higher recurrence rate of dislocation when using absorbable suture anchors (17% in absorbable vs 7% in non-absorbable group). It is known that Panacryl® may be responsible for a major local inflammatory response. However, it is still unclear if this could be the failure etiology. Consequently, we prefer to use systematically non-absorbable sutureanchors for shoulder stabilization.

Geology, correlations, and geodynamic evolution of the Biga Peninsula (NW Turkey)

L?objectif de ce travail de recherche était de décrypter l?évolution géodynamique de la Péninsule de Biga (Turquie du N-O), à travers l?analyse de deux régions géologiques peu connues, le mélange de Çetmi et la zone d?Ezine (i.e. le Groupe d?Ezine et l?ophiolite de Denizgören). Une étude complète et détaillée de terrain (cartographie et échantillonnage) ainsi qu?une approche multidisciplinaire (sédimentologie de faciès, pétrographie sédimentaire et magmatique, micropaléontologie, datations absolues, géochimie sur roche totale, cristallinité de l?illite) ont permis d?obtenir de nouveaux éléments d?information sur la région considérée. ? Le mélange de Çetmi, de type mélange d?accrétion, affleure au nord et au sud de la Péninsule de Biga ; les principaux résultats de son étude peuvent se résumer comme suit: - Son aspect structural actuel (nature des contacts, organisation tectonique) est principalement dû au régime extensif Tertiaire présent dans la région. - Il est constitué de blocs de différentes natures : rares calcaires Scythien-Ladinien dans le faciès Han Bulog, blocs hectométriques de calcaires d?âge Norien-Rhaetien de rampe carbonatée, nombreux blocs décamétriques de radiolarites rouges d?âge Bajocien- Aptien, blocs/écailles de roches magmatiques de type spilites (basaltes à andésite), ayant des signatures géochimiques d?arcs ou intra-plaques. - La matrice du mélange est constituée d?une association greywacke-argilites dont l?âge Albien inférieur à moyen a été déterminé par palynologie. - L?activité du mélange s?est terminée avant le Cénomanien (discordance Cénomanienne au sommet du mélange, pas de bloc plus jeune que la matrice). - Du point de vue de ses corrélations latérales, le mélange de Çetmi partage plus de traits communs avec les mélanges se trouvant dans les nappes allochtones du Rhodope (nord de la Grèce et sud-ouest de la Bulgarie) qu?avec ceux de la suture Izmir-Ankara (Turquie); il apparaît finalement que sa mise en place s?est faite dans une logique balkanique (chevauchements vers le nord d?âge anté-Cénomanien). ? Le Groupe d?Ezine et l?ophiolite sus-jacente de Denizgören affleurent dans la partie ouest de la Péninsule de Biga. Le Groupe d?Ezine est une épaisse séquence sédimentaire continue (3000 m), subdivisée en trois formations, caractérisée chacune par un type de sédimentation spécifique, relatif à un environnement de dépôt particulier. De par ses caractéristiques (grande épaisseur, variations latérales de faciès et d?épaisseur dans les formations, érosion de matériel provenant de l?amont du bassin), le groupe d?Ezine est interprétée comme un dépôt syn-rift d?âge Permien moyen-Trias inférieur. Il pourrait représenter une partie de la future marge passive sud Rhodopienne à la suite de l?ouverture de l?océan Maliac/Méliata. L?ophiolite de Denizgören sus-jacente repose sur le Groupe d?Ezine par l?intermédiaire d?une semelle métamorphique à gradient inverse, du faciès amphibolite à schiste vert. L?âge du faciès amphibolite suggère une initiation de l?obduction au Barrémien (125 Ma, âge Ar/Ar); cet âge est unique dans le domaine égéen, mais il peut là aussi être relié à une logique balkanique, sur la base de comparaison avec le domaine Rhodopien. ? Toutes les unités précédentes (mélange de Çetmi, Groupe d?Ezine et ophiolite de Denizgören) ont passivement subi trois phases extensives pendant le Tertiaire. Dans la région d?Ezine et du mélange nord, les micaschistes HP sous-jacents ont été exhumés avant l?Eocène moyen. Dans le cas du mélange sud, cette exhumation Eocene est en partie enregistrée dans les mylonites séparant le mélange du dôme métamorphique sous-jacent du Kazda?. Le mélange sud est dans tous les cas fortement érodé à la suite de la double surrection du dôme du Kazda?, près de la lim ite Oligocène/Miocene et pendant le Plio- Quaternaire. Dans le premier cas, ce soulèvement est caractérisé par le développement d?une faille de détachement à faible pendage, qui contrôle à la fois l?exhumation du massif, et la formation d?un bassin sédimentaire syntectonique, de type bassin supradétachement; quant à la phase extensive la plus récente, elle est contrôlée par le jeu de failles normales à forts pendages qui remanient l?ensemble des structures héritées, et dictent la géomorphologie actuelle de la région. ? Il est possible de proposer un scénario pour l?évolution géodynamique de la Péninsule de Biga, basé sur l?ensemble des résultats précédents et sur les données de la géologie régionale ; ses points principaux sont: - La Péninsule de Biga fait partie de la marge Rhodopienne. - Le Groupe d?Ezine est un témoin de la marge passive nord Maliac/Méliata. - L?ophiolite de Denizgören et le mélange de Çetmi ont été mis en place tous deux vers le nord sur la marge précédente, respectivement au Barrémien et à l?Albien terminal- Cénomanien inférieur. - Une forte composante décrochante durant l?emplacement est suggérée par la préservation de fragments de la marge passive et l?absence de métamorphisme dans la plaque inférieure. - Tous les évènements précédents ont été largement affectés par le régime d?extension Tertiaire.<br/><br/>The purpose of this study is to unravel the geodynamic evolution of the Biga Peninsula (NW Turkey) through the detailed study of two poorly known areas, the Çetmi mélange and the Ezine zone (i.e. the Ezine Group and the Denizgören ophiolite). The methodology was based on a detailed field work and a multidisciplinary approach. ? The accretion-related Çetmi mélange is mainly cropping out north and south of the Biga Peninsula; the main results of its study can be summarized as follows: -Its present-day structural aspect (type of contacts, tectonic organisation) is largely inherited from the Tertiary extensional regime in the region. -It is made of blocks of various natures: Han Bulog limestones with a Scythian to Ladinian age, common carbonate ramp Norian-Rhaetian limestones (biggest blocks of the mélange), red radolarite with a Bajocian to Aptian age; the most common lithology of the mélange is made by block/slices of spilitic magmatic rocks (basalt to andesite); they have volcanic arc or within plate basalt geochemical signatures. -The matrix of the mélange is made of a greywacke-shale association of Early-Middle Albian age. - The mélange stopped its activity before the Cenomanian (no younger blocks than the matrix, and Cenomanian unconformity). - If compared to the regional geology, the Çetmi mélange shares some characteristics with the Izmir-Ankara mélanges (less), and with the mélanges from allochthonous nappes found in eastern Rhodope (more); it appears finally that its emplacement is related to a Balkanic logic (ante-Cenomanian northward thrusting). ? The Ezine Group and the overlying Denizgören ophiolite are cropping out in the western part of the Biga Peninsula. The Ezine Group is a thick sedimentary sequence interpreted as a syn-rift deposit of Middle Permian-Early Triassic age. It represents a part of the south Rhodopian passive margin, following the opening of the Maliac/Meliata oceanic domain. The Denizgören ophiolite has been emplaced northward on the Ezine Group in the Barremian (125 Ma, age of the amphibolitic sole); this age is unique in the Aegean domain, but here again, it may be related to a Balkan logic. ? All the previous units (Çetmi mélange, Ezine Group and Denizgören ophiolite) have passively suffered two extensional regimes during the Tertiary. In the Ezine and northern Çetmi mélange area, the underlying HP Çamlýca micaschists were exhumed before the Middle Eocene. As for the southern mélange, it was strongly eroded following the Late Oligocene to Quaternary uplift of the underlying Kazda? Massif. This uplift was characterized by the development of a low-angle detachment fault controlling a part of the exhumation, as well as the development of a supra-detachment basin. ? Based on the previous results, and on the data from the regional geology, one can propose a scenario for the geodynamic evolution of the Biga Peninsula. Its key points are:- The Biga Peninsula is belonging to the Rhodope margin. - The Ezine Group is a remnant of the northern Maliac/Meliata passive margin. - Both the Denizgören ophiolite and the Çetmi mélange have been emplaced northward on the previous margin, respectively in the Barremian and in the Late Albian-Early Cenomanian times. - The preservation of the remnants of the Rhodope margin, as well as the absence of metamorphism in the lower plate suggest a strong strike-slip component during the emplacements. - All the previous events are (at least) partly obliterated by the Tertiary extensional regime.<br/><br/>Le géologue est comme un «historien» de la Terre, qui porte un intérêt particulier à l?étude du passé de notre planète; ce dernier, très ancien, se mesure en dizaines ou centaines de millions d?années (Ma). Or le visage de la terre a constamment évolué au cours des ces millions d?années écoulés, car les plaques (continentales et océaniques) qui composent son enveloppe superficielle ne restent pas immobiles, mais se déplacent continuellement à sa surface, à une vitesse de l?ordre du cm/an (théorie de la tectonique des plaques); c?est ainsi, par exemple, que des océans naissent, grandissent, puis finissent par se refermer. On appelle sutures océaniques, les zones, aujourd?hui sur la terre ferme, où l?on retrouve les restes d?océans disparus. Ces sutures sont caractérisées par deux associations distinctes de roches, que l?on appelle les mélanges et les ophiolites; ces mélanges et ophiolites sont donc les témoins de l?activité passée d?un océan aujourd?hui refermé. L?équipe de recherche dans laquelle ce travail à été réalisé s?intéresse à un vaste domaine océanique fossile: l?océan Néotéthys. Cet océan, de plusieurs milliers de kilomètres de large, séparait alors l?Europe et l?Asie au nord, de l?Afrique, l?Inde et l?Australie au sud. De cet océan, il n?en subsiste aujourd?hui qu?une infime partie, qui se confond avec notre mer Méditerranée actuelle. Or, tout comme l?océan Pacifique est bordé de mers plus étroites (Mer de Chine, du Japon, etc?), l?océan Néotéthys était bordé au nord de mers marginales. C?est dans ce cadre que s?est inscrit mon travail de thèse, puisqu?il a consisté en l?étude d?une suture océanique (mélange plus ophiolite), témoin d?une des mers qui bordait l?océan Néotéthys sur sa marge nord. L?objectif était de préciser de quelle suture il s?agissait, puis de déterminer quand et comment elle avait fonctionné (i.e son évolution géologique). Les roches qui composent cette suture affleurent aujourd?hui en Turquie nord occidentale dans la Péninsule de Biga. Au nord et au sud de la péninsule se trouvent les zones géologique du mélange de Çetmi, et à l?ouest, le Groupe d?Ezine et l?ophiolite susjacente, dite ophiolite de Denizgören. Une étude complète et détaillée de terrain (cartographie, échantillonnage), suivie de diverses analyses en laboratoire (détermination de leur âge, de leur condition de formation, etc?), ont permis d?aboutir aux principaux résultats suivants : - Mise en évidence dans le mélange de Çetmi des témoins (1) de l?océan Lycien disparu (ancienne mer marginale de la Néotéthys), et (2) de la marge continentale qui le bordait au nord. - Fin de l?activité du mélange de Çetmi il y a environ 105 Ma (Albien). - Le mélange de Çetmi est difficilement corrélable dans le temps avec les unités semblables affleurant dans la région d?étude (unicité du mélange), ce qui implique des conditions particulière de formation. - L?ophiolite de Denizgören est un morceau d?océan Lycien posé sur un reste préservé de sa marge continentale nord. - Cette dernière est représentée sur le terrain par une succession de roches caractéristiques, le Groupe d?Ezine. Celui-ci est lui-même un témoin de l?ouverture d?un océan marginal de la Néotethys antérieur au Lycien, l?océan Maliac, qui s?est ouvert il y a 245 Ma (Permien-Trias). - La mise en place de l?ophiolite de Denizgören sur le Groupe d?Ezine (125 Ma, Barrémien) est antérieure à la mise en place du mélange de Çetmi. - Il apparaît que ces deux mises en place sont contemporaines de la formation de la chaîne des Balkans, terminée avant le Cénomanien (100 Ma). - L?évolution dans le temps des objets précédents (océans, marges continentales) montre de grands mouvements latéraux est-ouest entre ces objets (translation). Ce qui implique que les roches que l?on retrouve aujourd?hui sur un transect nord-sud ne l?étaient pas nécessairement auparavant. - Enfin, il s?avère que le mélange de Çetmi, l?ophiolite de Denizgören, et le Groupe d?Ezine ont subi par la suite des déformations extensives importantes qui ont considérablement perturbé le schéma post-mise en place.

Peripheral Nerve Repair: Multimodal Comparison of the Long-Term Regenerative Potential of Adipose Tissue-Derived Cells in a Biodegradable Conduit.

Tissue engineering is a popular topic in peripheral nerve repair. Combining a nerve conduit with supporting adipose-derived cells could offer an opportunity to prevent time-consuming Schwann cell culture or the use of an autograft with its donor site morbidity and eventually improve clinical outcome. The aim of this study was to provide a broad overview over promising transplantable cells under equal experimental conditions over a long-term period. A 10-mm gap in the sciatic nerve of female Sprague-Dawley rats (7 groups of 7 animals, 8 weeks old) was bridged through a biodegradable fibrin conduit filled with rat adipose-derived stem cells (rASCs), differentiated rASCs (drASCs), human (h)ASCs from the superficial and deep abdominal layer, human stromal vascular fraction (SVF), or rat Schwann cells, respectively. As a control, we resutured a nerve segment as an autograft. Long-term evaluation was carried out after 12 weeks comprising walking track, morphometric, and MRI analyses. The sciatic functional index was calculated. Cross sections of the nerve, proximal, distal, and in between the two sutures, were analyzed for re-/myelination and axon count. Gastrocnemius muscle weights were compared. MRI proved biodegradation of the conduit. Differentiated rat ASCs performed significantly better than undifferentiated rASCs with less muscle atrophy and superior functional results. Superficial hASCs supported regeneration better than deep hASCs, in line with published in vitro data. The best regeneration potential was achieved by the drASC group when compared with other adipose tissue-derived cells. Considering the ease of procedure from harvesting to transplanting, we conclude that comparison of promising cells for nerve regeneration revealed that particularly differentiated ASCs could be a clinically translatable route toward new methods to enhance peripheral nerve repair.

Endoscopic epiglottopexy using Lichtenberger's needle carrier to avoid breakdown of repair.

Severe type III laryngomalacia LM is represented by a retroflexed epiglottis that touches the posterior pharyngeal wall and obstructs the laryngeal inlet. Endoscopic epiglottopexy is advised in such cases wherein pexy sutures are passed between the epiglottis and base of tongue. Using conventional needle carriers, it is difficult to pass such sutures that go deep enough into the tongue base. Such a pexy is prone to a break down. We describe a novel technique of placing these glossoepiglottic sutures using the Lichtenberger's needle carrier. We used this technique in three patients with excellent results and report no complications. We propose to use this technique in cases of epiglottic prolapse seen in severe LM and certain hypotonic conditions.

Apical closure device for transapical valve procedures?.

OBJECTIVES: Transapical transcatheter valve procedures are performed through a left minithoracotomy and require apical sutures to seal the apical access site. The use of large-calibre devices compromises any attempt to fully perform the procedure with a thoracoscopic approach or percutaneously. We report our preliminary experience in animals with a new sutureless self-expandable apical occluder, engineered to perform transapical access site closure in a minimally invasive setting with large-size introducer sheaths. METHODS: The apical occluder with extendable waist was implanted in six young pigs during an acute animal study. Under general anaesthesia, animals (mean weight: 62 ± 8 kg) received full heparinization (heparin: 100 UI/kg; activated clotting time above 250 s). Through a median sternotomy, a 21-Fr Certitude? introducer sheath (outer diameter: 25 Fr) was placed over the wire into the cardiac apex. The delivery catheter carrying the constrained apical plug was inserted into the sheath and deployed under fluoroscopic control, whereas the Certitude? was retrieved. After protamine infusion, we observed and recorded the 1-h bleeding with standard haemodynamic parameters. Animals were sacrificed, and hearts analysed. RESULTS: Six apical closure devices were successfully introduced and deployed in six pig hearts through large-size apical sheaths at first attempt. In all animals, the plugs guaranteed immediate apical sealing and traces of blood were collected in the pericardium during the 1-h observational period (mean of 16 ± 3.4 ml of blood loss per animal). Haemodynamic parameters remained stable during the entire study period and no plug dislodgement was detected with normal systemic blood pressure (mean arterial mean blood pressure: 65 ± 7 mmHg). Post-mortem analysis confirmed the full deployment and good fixation of all plugs, without macroscopic damages to the surrounding myocardium. CONCLUSIONS: This sutureless self-expandable apical occluder is a simple device capable of sealing large-size apical access sites (20-35 Fr) in an acute animal study. This approach is a step further towards less invasive transapical valve procedures in the clinical setting, and further animal tests will be performed to confirm the long-term efficacy and safety of this device.

Apical access and closure devices for transapical transcatheter heart valve procedures.

The majority of transcatheter aortic valve implantations, structural heart procedures and the newly developed transcatheter mitral valve repair and replacement are traditionally performed either through a transfemoral or a transapical access site, depending on the presence of severe peripheral vascular disease or anatomic limitations. The transapical approach, which carries specific advantages related to its antegrade nature and the short distance between the introduction site and the cardiac target, is traditionally performed through a left anterolateral mini-thoracotomy and requires rib retractors, soft tissue retractors and reinforced apical sutures to secure, at first, the left ventricular apex for the introduction of the stent-valve delivery systems and then to seal the access site at the end of the procedure. However, despite the advent of low-profile apical sheaths and newly designed delivery systems, the apical approach represents a challenge for the surgeon, as it has the risk of apical tear, life-threatening apical bleeding, myocardial damage, coronary damage and infections. Last but not least, the use of large-calibre stent-valve delivery systems and devices through standard mini-thoracotomies compromises any attempt to perform transapical transcatheter structural heart procedures entirely percutaneously, as happens with the transfemoral access site, or via a thoracoscopic or a miniaturised video-assisted percutaneous technique. During the past few years, prototypes of apical access and closure devices for transapical heart valve procedures have been developed and tested to make this standardised successful procedure easier. Some of them represent an important step towards the development of truly percutaneous transcatheter transapical heart valve procedures in the clinical setting.