Asymmetric mass ratios for bright double neutron-star mergers.

The discovery of a radioactively powered kilonova associated with the binary neutron-star merger GW170817 remains the only confirmed electromagnetic counterpart to a gravitational-wave event1,2. Observations of the late-time electromagnetic emission, however, do not agree with the expectations from standard neutron-star merger models. Although the large measured ejecta mass3,4 could be explained by a progenitor system that is asymmetric in terms of the stellar component masses (that is, with a mass ratio q of 0.7 to 0.8)5, the known Galactic population of merging double neutron-star systems (that is, those that will coalesce within billions of years or less) has until now consisted only of nearly equal-mass (q > 0.9) binaries6. The pulsar PSR J1913+1102 is a double system in a five-hour, low-eccentricity (0.09) orbit, with an orbital separation of 1.8 solar radii7, and the two neutron stars are predicted to coalesce in [Formula: see text] million years owing to gravitational-wave emission. Here we report that the masses of the pulsar and the companion neutron star, as measured by a dedicated pulsar timing campaign, are 1.62 ± 0.03 and 1.27 ± 0.03 solar masses, respectively. With a measured mass ratio of q = 0.78 ± 0.03, this is the most asymmetric merging system reported so far. On the basis of this detection, our population synthesis analysis implies that such asymmetric binaries represent between 2 and 30 per cent (90 per cent confidence) of the total population of merging binaries. The coalescence of a member of this population offers a possible explanation for the anomalous properties of GW170817, including the observed kilonova emission from that event.

Comparative genomics of Mortierella elongata and its bacterial endosymbiont Mycoavidus cysteinexigens.

Endosymbiosis of bacteria by eukaryotes is a defining feature of cellular evolution. In addition to well-known bacterial origins for mitochondria and chloroplasts, multiple origins of bacterial endosymbiosis are known within the cells of diverse animals, plants and fungi. Early-diverging lineages of terrestrial fungi harbor endosymbiotic bacteria belonging to the Burkholderiaceae. We sequenced the metagenome of the soil-inhabiting fungus Mortierella elongata and assembled the complete circular chromosome of its endosymbiont, Mycoavidus cysteinexigens, which we place within a lineage of endofungal symbionts that are sister clade to Burkholderia. The genome of M. elongata strain AG77 features a core set of primary metabolic pathways for degradation of simple carbohydrates and lipid biosynthesis, while the M. cysteinexigens (AG77) genome is reduced in size and function. Experiments using antibiotics to cure the endobacterium from the host demonstrate that the fungal host metabolism is highly modulated by presence/absence of M. cysteinexigens. Independent comparative phylogenomic analyses of fungal and bacterial genomes are consistent with an ancient origin for M. elongata - M. cysteinexigens symbiosis, most likely over 350 million years ago and concomitant with the terrestrialization of Earth and diversification of land fungi and plants.

Autotrasplante de células madre adultas en miembros inferiores con isquemia crítica / Adult stem cell autotransplantation in chronic critical limb ischemia

INTRODUCCIÓN. Recientemente se ha hecho evidente el potencial terapéutico de las células madre adultas en el tratamiento de arteriopatías periféricas, pues la implantación en los miembros isquémicos de células mononucleares procedentes de la médula ósea (CMN-MO) o de la sangre periférica (CMN-SP) puede mejorar la vascularization del tejido. MATERIAL Y MÉTODO. Se trataron 30 pacientes con isquemia critica de un miembro inferior, en los que no existía ninguna posibilidad de revascularización por métodos tradicionales. En 13 se implantaron CMN-MO autólogas en el miembro isquémico y en 17 se utilizaron CMN-SP. Los pacientes se monitorearon durante 24 semanas con el índice de presiones tobillo-brazo (ITB) en reposo, la distancia de marcha sin claudicación y la evaluación de la escala del dolor de reposo. RESULTADOS. Veintiún pacientes tenían indicación de amputación mayor del miembro afectado y en catorce (67%) de ellos se logró evitar. Tanto en los pacientes en que se emplearon CMN-MO como en los que recibieron CMN-SP hubo mejoría significativa del ITB en el miembro en que se hizo la implantación celular. El dolor de reposo mejoró significativamente en ambos grupos a las 4 semanas y a las 24 semanas había desaparecido. La distancia de marcha sin claudicación mejoró progresivamente en los dos grupos. En ningún caso se observaron efectos adversos secundarios al tratamiento. CONCLUSIONES. Los métodos de implantación de CMN-MO y de CMN-SP autólogas en pacientes con isquemia crítica de miembros inferiores resultaron procedimientos eficaces y sin complicaciones, lo que estimula a la continuación de los estudios clínicos en este campo (AU)

INTRODUCTION. Recently the therapeutic potential of adult stem cells in the treatment of peripheral arterial diseases has become increasingly evident, since implantation of bone marrow mononuclear cells (BM-MNC) or peripheral blood mononuclear cells (PB-MNC) into ischemic limbs can improve tissue vascularization. PATIENTS AND METHODS. Thirty patients with severe unilateral lower limb ischemia, with no option for standard revascularization therapies, were treated. Autologous BM-MNC were implanted into the ischemic limb in 13 cases and 17 received PBMNC. The patients were monitored during 24 weeks with resting ankle-brachial pressure index (ABI), pain-free walking distance and rest pain scale evaluation. RESULTS. Twenty one patients had been specifically advised to undergo major limb amputation that was avoided in 14 (67%). ABI significantly improved in the treated limb in both groups. Rest pain significantly improved in both groups at week 4 and at 24 weeks patients were completely pain-free. Pain free walking distance progressively improved in both groups. No related adverse effects were observed in any patient throughout the therapeutic procedure. CONCLUSIONS. The methods of autologous BM-MNC and PB-MNC implantation in patients with critical lower limb ischemia showed to be effective procedures without related complications. These results encourage to continue clinical studies in this field (AU)

Autologous bone-marrow mononuclear cell implantation in patients with severe lower limb ischaemia: a comparison of using blood cell separator and Ficoll density gradient centrifugation.

Different studies have provided evidence that implantation of bone-marrow mononuclear cells (BM-MNC) into ischaemic limbs can improve tissue vascularization. Based on these results we performed a pilot study in patients with critical lower limb ischaemia to assess efficacy and safety of implantation of autologous BM-MNC. The amount and efficacy of BM-MNC purified either by an automated method or by a manual procedure were compared. Twelve patients with severe unilateral lower limb ischaemia were entered into this study. They were randomly assigned to be injected with BM-MNC sorted on a blood cell separator or isolated by density gradient on Ficoll-Hypaque. BM-MNC were implanted into the ischaemic legs. Patients were monitored with resting ankle-brachial pressure index (ABI), arterial oxygen saturation (SaO(2)), pain-free walking time and rest pain scale evaluation. The automated and manual methods used for mononuclear cell separation gave results not significantly different. Monitored variables improved in both groups. Improvement of ischaemic condition persisted during 24 weeks follow-up. Limb salvage was achieved in five cases. Our results indicate that BM-MNC implantation into ischaemic limbs is a practical, safe and effective method that may significantly contribute to the management of patients with limb ischaemia. The Ficoll method is a simple and effective procedure for BM-MNC concentration that may be useful, mainly in hospitals without sophisticated facilities.