A re-examination of the nama-type Vendian organism Rangea schneiderhoehni

The need to re-examine Rangea has been motivated by two factors: first, by the recent progress in the understanding of three-dimensional mouldic preservation of Vendian fossils, and second, by discoveries of this taxon outside Gondwana albeit in the same sedimentary environment as seen\ud in Namibia. Several important features are revealed, including the in situ posture in the sediment, the\ud double-layered quilted structure, the tripartite stemless body and the mucous-supported sheath in the sediment. It is suggested that Rangea represents an infaunal organism, and that the similarity with other members of the Nama-type biota reflects convergence in functional and fabricational constraints in relation to infaunal life habit

Sesgo tafonómico en los datos de distribución de Cloudina en Siberia

Cloudina-morph fossils in Siberia have been traditionally regarded as a taphonomic mode of Anabarites tests inserted one into another under specific hydrodynamic conditions. Clusters of telescoped conical tests are ubiquitous in the Kessyusa Group and coeval strata across Siberia and not all of them can be easily interpreted as a result of simple mechanical stacking. It remains to be confirmed whether any of these clusters actually represents a life association of a Cloudina-morph structure.En Siberia los morfotipos de Cloudina han sido tradicionalmente considerados como una variedad tafonómica de conchas de Anabarites, insertadas una dentro de otra, bajo condiciones hidrodinámicas específicas. Las asociaciones de conchas cónicas telescópicas son omnipresentes en el Grupode Kessyusa y en estratos contemporáneos a lo largo de Siberia, y no todos ellos pueden ser fácilmente interpretados como resultado de un simple apilamiento mecánico. Queda por ver si alguna de estas bioacumulaciones representa una asociación de vida de una estructura morfotípica de tipo Cloudina

La aparición de Dickinsonia en facies no marinas

Dickinsonia in the central Urals occurs in a succession transitional from marginal marine to non-marine. Even within this sequence Dickinsonia appears to be restricted to the least marine facies interpreted as a coastal lagoon surrounded by tidal flats. Another puzzling aspect is the complete absence of other Ediacaran taxa that are usually found together with Dickinsonia in other fossil localities. In fact, the Sinii Kamen Member of the Cherny Kamen Formation yielded an assemblage of Ediacaran macrofossils including aspidellamorph and mawsonitomorph holdfasts, frondomorphs, palaeopascichnids, and concentric ring structures of microbial origin; however, fossils of Dickinsonia have never been found in this association.En los Urales centrales, Dickinsonia se encuentra en medios de transición entre sustratos continentales y marinos marginales, generalmente de tipo laguna costera rodeada por llanuras mareales. Otro aspecto llamatico es la ausencia de otros taxones ediacáricos asociados con Dickinsonia, relativamente abundantes en otros medios. De hecho, el Miembro de Sinii Kamen de la Formación de Cherny Kamen ha librado una asociación de macrofósiles ediacáricos, que incluye anclajes de tipo aspidellamorfo y mawsonitomorfo, frondomorfos, palaeopascichnidos y estructuras en anillos concéntricos de origen microbiano, con los que no se asocia Dickinsonia

Ecología de Dickinsonia en llanuras mareales

Specimens of Dickinsonia from the Central Urals are characterised by clear bilateral symmetry. Taking into account observations from Australian specimens, we consider that the so called ‘glide reflection symmetry’ in these fossils is a taphonomic phenomenon. The size frequency distribution plot shows the predominance of smaller individuals in the studied population of Dickinsonia from the Central Urals. Assuming that the age of an individual is manifested in the body size, there is a significant predominance of juvenile individuals in the population. Three possible scenarios can be envisaged: (i) the population has a large number of juvenile individuals as the result of high survivorship rate in the intertidal zone; (ii) the population teems with juvenile forms because it is buried immediately after hatching; (iii) assuming that Dickinsonia was an actively motile organisms, that abundance of juvenile individuals could be explained by their inability to escape burial (although it is difficult to imagine that some of the mature individuals are buried with signs of escape behaviour); and (iv) the population could be interpreted as a fossilised ‘nesting ground’ for Dickinsonia in the intertidal zone where juvenile forms underwent maturation before migrating back to the subtidal zone. The study population can be characterised as expanding or stable; therefore, the intertidal setting can be described as favourable for these organisms.Los ejemplares de Dickinsonia de los Urales Centrales se caracterizan por una clara simetría bilateral. Tomando en cuenta las observaciones de especímenes australianos, consideramos que la llamada’simetría de reflexión por deslizamiento’ en estos fósiles es un fenómeno tafonómico. El gráfico de distribución de frecuencias de tamaño muestra el predominio de individuos juveniles en la población estudiada de Dickinsonia de los Urales Centrales. Asumiendo que la edad de un individuo se manifiesta por su tamaño, existe un predominio significativo de individuos juveniles en la población. Se pueden prever tres escenarios posibles: (1) la población tiene un gran número de individuos juveniles como resultado de la alta tasa de supervivencia en la zona intermareal; (2) la población está dominada por formas juveniles porque está enterrada inmediatamente después de la eclosión; (3) suponiendo que Dickinsonia fuera un organismo móvil activo, la abundancia de individuos juveniles podría explicarse por su incapacidad para escapar del entierramiento (aunque es difícil imaginar que algunos de los individuos maduros estén enterrados con signos de comportamiento de escape); y (4) la población podría interpretarse como un “lugar de nidificación” fosilizado para Dickinsonia en la zona intermareal, donde las formas juveniles maduraron antes de migrar a la zona submareal. La población de estudio puede caracterizarse como en expansión o estable; por lo tanto, el entorno intermareal puede describirse como favorable para estos organismo

Remarkable preservation of microbial mats in Neoproterozoic siliciclastic settings : Implications for Ediacaran taphonomic models

The authors thank Duncan McIlroy and Alex Liu for their discussions, help, comments and field support, the National Trust for access to Longmyndian localities, and the staff of the British Geological Survey Palaeontology unit and the Oxford University Museum of Natural History for their assistance with access to materials. The comments and suggestions of two anonymous reviewers and Nora Noffke significantly improved the manuscript.Peer reviewedPostprin

The tempo of Ediacaran evolution

The rise of complex macroscopic life occurred during the Ediacaran Period, an interval that witnessed large-scale disturbances to biogeochemical systems. The current Ediacaran chronostratigraphic framework is of insufficient resolution to provide robust global correlation schemes or test hypotheses for the role of biogeochemical cycling in the evolution of complex life. Here, we present new radio-isotopic dates from Ediacaran strata that directly constrain key fossil assemblages and large-magnitude carbon cycle perturbations. These new dates and integrated global correlations demonstrate that late Ediacaran strata of South China are time transgressive and that the 575- to 550-Ma interval is marked by two large negative carbon isotope excursions: the Shuram and a younger one that ended ca. 550 Ma ago. These data calibrate the tempo of Ediacaran evolution characterized by intervals of tens of millions of years of increasing ecosystem complexity, interrupted by biological turnovers that coincide with large perturbations to the carbon cycle

Anaesthesia-Specifi c Oxygen Transport Assessment in Robot-Assisted Pelvic Surgery: a Clinical Trial

Background. Robot-assisted pelvic surgery rapidly becomes a choice in surgeries for gynaecological oncology and urology. These interventions require special settings (pneumoperitonaeum and Trendelenburg position), which inevitably and systemically impact oxygen transport. Low oxygen delivery during surgery associates with manifold adverse outcomes. A single universal oxygen delivery threshold is impractical, as oxygen consumption must be taken into account. This study examines the effects of pneumoperitonaeum and Trendelenburg position on oxygen transport in patients of ASA functional class I–III (as per American Society of Anaesthesiologists).Materials and methods. Delivery, consumption, oxygen extraction, perioperative adverse events and type of general anaesthesia were prospectively studied in 126 adult patients.Results and discussion. Mean oxygen consumption was 242 mL/min/m2 , mean oxygen delivery — 612 mL/min/m2 . Oxygen delivery was below median 529 mL/min/m2 in 54 (43  %) patients. Perioperative adverse events developed in 36 (29 %) patients. A strong correlation (r > 0.500; p<0.001) between oxygen delivery and consumption was observed in 54 patients. Blood lactate level of 2.7 mmol/L at surgery end was indicative of inadequate oxygen delivery.Conclusion. No relationship was revealed between oxygen delivery and adverse perioperative events, and neither — between oxygen delivery and consumption relative to a particular anaesthetic

Экстракорпоральная мембранная оксигенация при остром инфаркте миокарда, осложненном кардиогенным шоком

Cardiogenic shock is one of the main causes of death in patients with acute myocardial infarction with the mortality rates being as high as 60—80%. Extracorporeal membrane oxygenation (ECMO) is a life-saving technique in patients with cardiogenic shock. Subjects and methods. Veno-arterial ECMO was connected and the coronary arteries were stented in a 53-year-old female patient with acute myocardial infarction complicated by severe cardiogenic shock refractory to drug therapy and intra-aortic counterpulsation (IACP). ECMO was maintained at a volumetric perfusion rate of 4.5 l/min (2.5 l/min/m2). The duration of ECMO was 138.5 hours (5.8 days); that of IACP was 9 days. In the first 24 hours, there were no ECMO-related complications apart from mild bleeding from the site of cannula insertion. The patient stayed in the intensive care unit 12 days. Results. IACP is used to treat cardiogenic shock, but it is ineffective in severe cardiogenic shock. ECMO is one of the possible options for maintaining life and for stabilizing the condition. Current ECMO systems may be employed for urgent peripheral connection and coronary artery intervention. ECMO may be used for resuscitation and temporary life support, which permits as high as 50—75% of patients with refractory cardiogenic shock to be saved. Conclusion: emergency coronary stenting with ECMO support is the technique of choice for the treatment of acute myocardial infarction complicated by severe cardiogenic shock. Key words: extracorporeal membrane oxygenation, cardiogenic shock, coronary artery stenting.Кардиогенный шок — одна из основных причин смерти пациентов с острым инфарктом миокарда и летальность при этом составляет 60-80%. ЭКМО — экстракорпоральная мембранная оксигенация — является методом жизнеобеспечения у больных с кардиогенным шоком. Материалы и методы: пациентка 53 лет с острым инфарктом миокарда, осложненным тяжелым кардиогенным шоком, рефрактерным к медикаментозной терапии и внутриаортальной баллонной контрпульсации (ВАБК). Больной была подключена вено-артериальная ЭКМО и выполнено стентирование коронарных артерий. ЭКМО поддерживалась с объемной скоростью перфузии 4,5 л/мин (2,5 л/мин/м2). Продолжительность ЭКМО составила 138,5 часов (5,8 сут), продолжительность ВАБК — 9 суток. За исключением небольшого кровотечения в первые сутки из места установки артериальной канюли, осложнений, связанных с ЭКМО, не отмечено. В отделении реанимации пациентка находилась 12 суток. Результаты: для лечения кардиогенного шока используется ВАБК, которая при тяжелом кардиогенном шоке малоэффективна. Одним из возможных способов жизнеобеспечения и стабилизации состояния является ЭКМО. Современные системы ЭКМО могут использоваться для ургентного периферического подключения и обеспечения вмешательства на коронарных артериях. ЭКМО можно использовать для реанимации и временного поддержания жизни, что позволяет спасти до 50—75% больных с рефрактерным кардиогенным шоком. Выводы: неотложное коронарное стентирование с поддержкой ЭКМО является эффективным методом лечения острого инфаркта миокарда, осложненного тяжелым кардиогенным шоком. Ключевые слова: ЭКМО, кардиогенный шок, стентирование коронарных артерий

Cryptic Disc Structures Resembling Ediacaran Discoidal Fossils from the Lower Silurian Hellefjord Schist, Arctic Norway

The Hellefjord Schist, a volcaniclastic psammite-pelite formation in the Caledonides of Arctic Norway contains discoidal impressions and apparent tube casts that share morphological and taphonomic similarities to Neoproterozoic stem-holdfast forms. U-Pb zircon geochronology on the host metasediment indicates it was deposited between 437 ± 2 and 439 ± 3 Ma, but also indicates that an inferred basal conglomerate to this formation must be part of an older stratigraphic element, as it is cross-cut by a 546 ± 4 Ma pegmatite. These results confirm that the Hellefjord Schist is separated from underlying older Proterozoic rocks by a thrust. It has previously been argued that the Cambrian Substrate Revolution destroyed the ecological niches that the Neoproterozoic frond-holdfasts organisms occupied. However, the discovery of these fossils in Silurian rocks demonstrates that the environment and substrate must have been similar enough to Neoproterozoic settings that frond-holdfast bodyplans were still ecologically viable some hundred million years later

Оценка транспорта кислорода в зависимости от вида анестезии при робот-ассистированных операциях на органах малого таза: клиническое исследование

Background. Robot-assisted pelvic surgery rapidly becomes a choice in surgeries for gynaecological oncology and urology. These interventions require special settings (pneumoperitonaeum and Trendelenburg position), which inevitably and systemically impact oxygen transport. Low oxygen delivery during surgery associates with manifold adverse outcomes. A single universal oxygen delivery threshold is impractical, as oxygen consumption must be taken into account. This study examines the effects of pneumoperitonaeum and Trendelenburg position on oxygen transport in patients of ASA functional class I–III (as per American Society of Anaesthesiologists).Materials and methods. Delivery, consumption, oxygen extraction, perioperative adverse events and type of general anaesthesia were prospectively studied in 126 adult patients.Results and discussion. Mean oxygen consumption was 242 mL/min/m2 , mean oxygen delivery — 612 mL/min/m2 . Oxygen delivery was below median 529 mL/min/m2 in 54 (43  %) patients. Perioperative adverse events developed in 36 (29 %) patients. A strong correlation (r > 0.500; p<0.001) between oxygen delivery and consumption was observed in 54 patients. Blood lactate level of 2.7 mmol/L at surgery end was indicative of inadequate oxygen delivery.Conclusion. No relationship was revealed between oxygen delivery and adverse perioperative events, and neither — between oxygen delivery and consumption relative to a particular anaesthetic.Введение. Робот-ассистированные операции на  органах малого таза стремительно становятся способом хирургического лечения в онкологической гинекологии и урологии. Данные операции требуют специальных условий проведения (пневмоперитонеум и положение Тренделенбурга), которые неизбежно оказывают системное влияние на транспорт кислорода. Низкая доставка кислорода во время операции связана с целым рядом неблагоприятных исходов. Единое универсальное критическое значение доставки кислорода нецелесообразно, поскольку необходимо учитывать потребление кислорода. В этом исследовании изучалось влияние пневмоперитонеума и положения Тренделенбурга на транспорт кислорода у пациентов I–III функциональных классов American Society of Anesthesiologists (ASA).Материалы и методы. Доставка, потребление, экстракция кислорода, периоперационные неблагоприятные события и вид общей анестезии были проспективно изучены у 126 взрослых пациентов.Результаты и обсуждение. Среднее потребление кислорода составило 242 мл/мин/м 2, средняя доставка кислорода 612 мл/мин/м 2. У 54 (43 %) пациентов доставка кислорода была ниже медианы 529 мл/мин/м 2. У 36 (29 %) пациентов развились периоперационные неблагоприятные события. У 54 пациентов была сильная корреляция (r > 0,500; р < 0,001) между доставкой и потреблением кислорода. Уровень лактата в крови в конце операции 2,7 ммоль/л свидетельствовал о недостаточной доставке кислорода.Заключение. Мы не  обнаружили взаимосвязи между уровнем доставки кислорода и  нежелательными периоперационными событиями, а также не обнаружили взаимосвязи между доставкой и потреблением кислорода в зависимости от используемого анестетика