214 research outputs found

    Preservation of nautilid soft parts inside and outside the conch interpreted as central nervous system, eyes, and renal concrements from the Lebanese Cenomanian

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    Nautilid, coleoid and ammonite cephalopods preserving jaws and soft tissue remains are moderately common in the extremely fossiliferous Konservat-LagerstÀtte of the Hadjoula, Haqel and Sahel Aalma region, Lebanon. We assume that hundreds of cephalopod fossils from this region with soft-tissues lie in collections worldwide. Here, we describe two specimens of Syrionautilus libanoticus (Cymatoceratidae, Nautilida, Cephalopoda) from the Cenomanian of Hadjoula. Both specimens preserve soft parts, but only one shows an imprint of the conch. The specimen without conch displays a lot of anatomical detail. We homologise the fossilised structures as remains of the digestive tract, the central nervous system, the eyes, and the mantle. Small phosphatic structures in the middle of the body chamber of the specimen with conch are tentatively interpreted as renal concrements (uroliths). The absence of any trace of arms and the hood of the specimen lacking its conch is tentatively interpreted as an indication that this is another leftover fall (pabulite), where a predator lost parts of its prey. Other interpretations such as incomplete scavenging are also conceivable

    Evidence for a coordination position available to solute molecules on one of the metals at the active center of reduced bovine superoxide dismutase

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    We have measured the contribution of the reduced form of bovine Zn/Cu superoxide dismutase to the relaxation of the 35Cl nucleus of chloride ion. The reduced protein has a molar relaxivity approximately 2.5 greater than the metal free protein, and addition of a small excess of cyanide lowers the relaxivity of the reduced protein to that of the apo-protein. We have interpreted these observations in terms of an open coordination position on one of the two metal ions, and we have proposed a mechanism for the reduction of superoxide by reduced superoxide dismutase which requires that binds to Cu+ prior to electron transfer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21715/1/0000107.pd

    Studies on the reconstitution of bovine erythrocyte superoxide dismutase : V. Preparation and properties of derivatives in which both zinc and copper sites contain copper

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    1. 1. We have developed a procedure for preparing derivatives of bovine superoxide dismutase in which primarily the Cu binding sites are occupied by Cu2+ (2 Cu2+-) and in which both the Zn and Cu binding sites are occupied by Cu2+ (4 Cu2+-).2. 2. The 2 Cu2+ protein shows approximately one-half the superoxide dismutase activity of an equivalent amount of native protein. A two-fold enhancement of the activity of 2 Cu2+-dismutase was observed upon occupation of the Zn sites either with Zn2+ or Cu2+.3. 3. The electron paramagnetic resonance spectrum of 4 Cu2+ protein was recorded over the temperature range 5-100 [deg]K and the results suggest an antiferromagnetic interaction between Cu2+ in the Zn site and Cu2+ in the Cu site having a coupling constant of approx. 52 cm-1.4. 4. The binuclear Cu2+ complex was found to accept only one electron from ferrocyanide.5. 5. One-half the total Cu+ of dithionite reduced 4 Cu+ protein was found to react rapidly with bathocupreine sulfonate whereas the other half reacted slowly. Reduced native protein did not react with bathocupreine sulfonate below 70 [deg]C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22003/1/0000416.pd

    Controlling crystallization and its absence: Proteins, colloids and patchy models

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    The ability to control the crystallization behaviour (including its absence) of particles, be they biomolecules such as globular proteins, inorganic colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and technological importance. Much can be learnt from the exquisite control that biological systems exert over the behaviour of proteins, where protein crystallization and aggregation are generally suppressed, but where in particular instances complex crystalline assemblies can be formed that have a functional purpose. We also explore the insights that can be obtained from computational modelling, focussing on the subtle interplay between the interparticle interactions, the preferred local order and the resulting crystallization kinetics. In particular, we highlight the role played by ``frustration'', where there is an incompatibility between the preferred local order and the global crystalline order, using examples from atomic glass formers and model anisotropic particles.Comment: 11 pages, 7 figure

    Neuron-derived transthyretin modulates astrocytic glycolysis in hormone-independent manner

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    It has been shown that neurons alter the expression of astrocytic metabolic enzymes by secretion of until now unknown molecule(s) into extracellular fluid. Here, we present evidence that neuron-derived transthyretin (TTR) stimulates expression of glycolytic enzymes in astrocytes which is reflected by an increased synthesis of ATP. The action of TTR is restricted to regulatory enzymes of glycolysis: phosphofructokinase P (PFKP) and pyruvate kinase M1/M2 isoforms (PKM1/2). The regulation of PFK and PKM expression by TTR is presumably specific for brain tissue and is independent of the role of TTR as a carrier protein for thyroxine and retinol. TTR induced expression of PKM and PFK is mediated by the cAMP/PKA-dependent pathway and is antagonized by the PI3K/Akt pathway. Our results provide the first experimental evidence for action of TTR as a neuron-derived energy metabolism activator in astrocytes and describe the mechanisms of its action. The data presented here suggest that TTR is involved in a mechanism in which neurons stimulate degradation of glycogen-derived glucosyl units without significant modulation of glucose uptake by glial cells

    Baseline characteristics of patients in the reduction of events with darbepoetin alfa in heart failure trial (RED-HF)

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    <p>Aims: This report describes the baseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF) which is testing the hypothesis that anaemia correction with darbepoetin alfa will reduce the composite endpoint of death from any cause or hospital admission for worsening heart failure, and improve other outcomes.</p> <p>Methods and results: Key demographic, clinical, and laboratory findings, along with baseline treatment, are reported and compared with those of patients in other recent clinical trials in heart failure. Compared with other recent trials, RED-HF enrolled more elderly [mean age 70 (SD 11.4) years], female (41%), and black (9%) patients. RED-HF patients more often had diabetes (46%) and renal impairment (72% had an estimated glomerular filtration rate <60 mL/min/1.73 m2). Patients in RED-HF had heart failure of longer duration [5.3 (5.4) years], worse NYHA class (35% II, 63% III, and 2% IV), and more signs of congestion. Mean EF was 30% (6.8%). RED-HF patients were well treated at randomization, and pharmacological therapy at baseline was broadly similar to that of other recent trials, taking account of study-specific inclusion/exclusion criteria. Median (interquartile range) haemoglobin at baseline was 112 (106–117) g/L.</p> <p>Conclusion: The anaemic patients enrolled in RED-HF were older, moderately to markedly symptomatic, and had extensive co-morbidity.</p&gt

    Biotic and environmental dynamics through the Late Jurassic-Early Cretaceous transition: evidence for protracted faunal and ecological turnover

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    The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/Cretaceous (J/K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic–Early Cretaceous events, focusing particularly on events closest to the J/K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/K boundary ‘event’, which hints at a ‘cascade model’ of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/K transition therefore, although not a mass extinction, represents an important transitional period in the co-evolutionary history of life on Earth

    Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

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    Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≄ II, EF ≀35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

    Phosphatized adductor muscle remains in a Cenomanian limid bivalve from Villers-sur-Mer (France)

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    Soft-tissue preservation in molluscs is generally rare, particularly in bivalves and gastropods. Here, we report a three-dimensionally preserved specimen of the limid Acesta clypeiformis from the Cenomanian of France that shows preservation of organic structures of the adductor muscles. Examination under UV-light revealed likely phosphatisation of organic remains, which was corroborated by EDX-analyses. We suggest that the parts of the adductor muscles that are very close to the attachment are particularly resistant to decay and thus may be preserved even under taphonomic conditions usually not favouring soft-tissue fossilisation
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