Author Correction: Unprecedented rains decimate surface microbial communities in the hyperarid core of the Atacama Desert.

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Unprecedented rains decimate surface microbial communities in the hyperarid core of the Atacama Desert.

The hyperarid core of the Atacama Desert, the driest and oldest desert on Earth, has experienced a number of highly unusual rain events over the past three years, resulting in the formation of previously unrecorded hypersaline lagoons, which have lasted several months. We have systematically analyzed the evolution of the lagoons to provide quantitative field constraints of large-scale impacts of the rains on the local microbial communities. Here we show that the sudden and massive input of water in regions that have remained hyperarid for millions of years is harmful for most of the surface soil microbial species, which are exquisitely adapted to survive with meager amounts of liquid water, and quickly perish from osmotic shock when water becomes suddenly abundant. We found that only a handful of bacteria, remarkably a newly identified species of Halomonas, remain metabolically active and are still able to reproduce in the lagoons, while no archaea or eukaryotes were identified. Our results show that the already low microbial biodiversity of extreme arid regions greatly diminishes when water is supplied quickly and in great volumes. We conclude placing our findings in the context of the astrobiological exploration of Mars, a hyperarid planet that experienced catastrophic floodings in ancient times.

Diversity of endosymbiotic Nostoc in Gunnera magellanica from Tierra del Fuego, Chile [corrected].

Global warming is causing ice retreat in glaciers worldwide, most visibly over the last few decades in some areas of the planet. One of the most affected areas is the region of Tierra del Fuego (southern South America). Vascular plant recolonisation of recently deglaciated areas in this region is initiated by Gunnera magellanica, which forms symbiotic associations with the cyanobacterial genus Nostoc, a trait that likely confers advantages in this colonisation process. This symbiotic association in the genus Gunnera is notable as it represents the only known symbiotic relationship between angiosperms and cyanobacteria. The aim of this work was to study the genetic diversity of the Nostoc symbionts in Gunnera at three different, nested scale levels: specimen, population and region. Three different genomic regions were examined in the study: a fragment of the small subunit ribosomal RNA gene (16S), the RuBisCO large subunit gene coupled with its promoter sequence and a chaperon-like protein (rbcLX) and the ribosomal internal transcribed spacer (ITS) region. The identity of Nostoc as the symbiont was confirmed in all the infected rhizome tissue analysed. Strains isolated in the present study were closely related to strains known to form symbioses with other organisms, such as lichen-forming fungi or bryophytes. We found 12 unique haplotypes in the 16S rRNA (small subunit) region analysis, 19 unique haplotypes in the ITS region analysis and 57 in the RuBisCO proteins region (rbcLX). No genetic variability was found among Nostoc symbionts within a single host plant while Nostoc populations among different host plants within a given sampling site revealed major differences. Noteworthy, interpopulation variation was also shown between recently deglaciated soils and more ancient ones, between eastern and western sites and between northern and southern slopes of Cordillera Darwin. The cell structure of the symbiotic relationship was observed with low-temperature scanning electron microscopy, showing changes in morphology of both cyanobiont cells (differentiate more heterocysts) and plant cells (increased size). Developmental stages of the symbiosis, including cell walls and membranes and EPS matrix states, were also observed.

[Prevention of postoperative nausea and vomiting in gynecologic surgery with 3 fixed doses of metoclopramide, droperidol or placebo]. / Prevención de las náuseas y vómitos postoperatorios en cirugía ginecológica mediante tres dosis fijas de metoclopramida, droperidol o placebo.

OBJECTIVES: To compare the efficacy and side effects of three doses of metoclopramide, droperidol or placebo administered every 8 h to prevent nausea and vomiting during the first 24 h after surgery. MATERIAL AND METHODS: Prospective, double blind study of 104 patients scheduled for major intraabdominal gynecological surgery under general anesthesia. The patients were randomly assigned to three groups: group M received 10 mg of metoclopramide, group D received 1.25 mg of droperidol and group P received a saline solution. The patients were premedicated with oral diazepam. All patients were anesthetized using similar techniques, with fentanyl, thiopental, vecuronium, oxygen/nitrogen protoxide and isoflurane. Muscle relaxation was reversed with atropine and neostigmine. Postoperative analgesia was given with endovenous morphine and metamizol. Immediately after surgery each patient received an endovenous dose of the assigned antiemetic drug. Patients were monitored for 24 h and observations were recorded every hour on the following scale: 0, for no emetic symptoms, 1 for nausea and 2 for vomiting. RESULTS: Fifteen patients (42.9%) in group D, 21 (60% in group M and 19 (54.3%) in group P experienced nausea during the 24 h after surgery, with no significant differences. However, the incidence of vomiting was significantly lower in group D, with 7 patients (20%) vomiting in group D versus 11 patients (31.43%) in group M and 17 (50%) in group P. Side effects were mild and required no treatment. CONCLUSIONS: Droperidol at a dose of 1.25 mg every 8 h is effective and safe for preventing postoperative nausea and vomiting and has minimal side effects. Metoclopramide at a dose of 10 mg every 8 h, in our study, was no better for the same purpose than placebo.

Prevención de las náuseas y vómitos postoperatorios en cirugía ginecológica mediante tres dosis fijas de metoclopramida, droperidol o placebo / Three fixed doses of metoclopramide, droperidol or placebo to prevent postoperative nausea and vomiting in gynecological surgery

OBJETIVOS. Comparar la eficacia de tres dosis administradas cada 8 h, de metoclopramida, droperidol o placebo, sobre la incidencia de náuseas y vómitos postoperatorios durante las primeras 24 h y valorar sus efectos secundarios. MATERIAL Y MÉTODOS. Estudio prospectivo, doble ciego sobre 104 pacientes programadas para cirugía ginecológica mayor intraabdominal bajo anestesia general. Las pacientes fueron asignadas de forma aleatoria en tres grupos: grupo M (10 mg de metoclopramida); grupo D (1,25 mg de droperidol), y grupo P (suero fisiológico). Las pacientes fueron premedicadas con diazepam por vía oral. Todas las pacientes fueron anestesiadas de forma similar con: fentanilo, tiopental, vecuronio, oxígeno/protóxido de nitrógeno e isoflurano. La relajación muscular se revirtió con atropina y neostigmina. La analgesia postoperatoria se realizó con morfina intravenosa y metamizol. Inmediatamente después de la intervención cada paciente recibió una dosis intravenosa del fármaco antiemético asignado. Las pacientes fueron controladas durante 24 h y las observaciones se recogieron cada hora según la siguiente escala: 0, ausencia de síntomas eméticos; 1, náuseas, y 2, vómitos. RESULTADOS . En las 24 h del postoperatorio tuvieron náuseas 15 pacientes (42,9 por ciento) del grupo D, 21 (60 por ciento) del grupo M y 19 (54,3 por ciento) del grupo P, sin que las diferencias fueran significativas. Sin embargo, la incidencia de vómitos fue significativamente menor en el grupo D, 7 pacientes (20 por ciento), respecto a los otros grupos, 11 pacientes (31,43 por ciento) en el grupo M y 17 (50 por ciento) en el grupo P. Los efectos secundarios fueron leves y no requirieron tratamiento. CONCLUSIONES. El droperidol a dosis de 1,25 mg cada 8 horas es un fármaco útil y seguro en la prevención de las náuseas y vómitos postoperatorios con mínimos efectos secundarios. La metoclopramida a dosis de 10 mg cada 8 h, en nuestro estudio, no demostró ser superior al placebo en la prevención de las náuseas y vómitos postoperatorios (AU)

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[Failure of obstetric epidural analgesia and its causes]. / Fallos en la analgesia epidural obstétrica y sus causas.

The frequency of failure to establish and maintain an epidural block is low in Spain for surgery but higher in obstetrics. The reasons are many, but noteworthy factors are the prior experience of the anesthesiologist, the anatomical features of the patient and the type of material used. However, we lack clinical and anatomical studies of the epidural space that would allow us to come to definitive conclusions. To reduce the number of failures in obstetrical analgesia, multi-holed catheters are recommended. Material and catheter permeability should be checked before puncture. The epidural needle should be directed toward the midline, air should not be injected into the epidural space. The anesthesiologist should avoid inserting too much of the epidural catheter and should assure firm support, checking it periodically and taking into account the patient's position. Finally the anesthetic dose should be adjusted to the progress of labor. The risk of incomplete analgesia and the possible need to insert a second epidural catheter must be discussed with the patient during preanesthetic evaluation.

Fallos en la analgesia epidural obstétrica y sus causas / Failure of epidural analgesia in obstetrics and its causes

Existe una tasa de fallos en la instauración y mantenimiento del bloqueo epidural cuya frecuencia es baja en los casos quirúrgicos y considerablemente más alta en las pacientes obstétricas. La causa es multifactorial, destacándose la experiencia previa del anestesiólogo, las características anatómicas del paciente y el tipo de material utilizado. Sin embargo, faltan estudios clínicos y anatómicos del espacio epidural para extraer conclusiones definitivas.Para reducir los fallos en analgesia obstétrica se recomienda el uso de catéteres multiperforados, la comprobación del material y de la permeabilidad del catéter antes de la punción, la correcta dirección de la aguja epidural hacia la línea media, evitar introducir aire en el espacio epidural, evitar la excesiva longitud de inserción del catéter epidural, asegurar su firme sujeción y revisión periódica, tener en cuenta la influencia de la posición de la paciente y, finalmente, la adecuación de las dosis anestésicas a la progresión del parto.El riesgo de una posible analgesia incompleta y la potencial necesidad de colocar un segundo catéter epidural debe ser discutido con la paciente durante la evaluación preanestésica (AU)

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Sedoanalgesia y relajación neuromuscular en el área de urgencias / Sedation, analgesia and neuromuscular relaxation in the emergency service

Revisión práctica de los principales fármacos analgésicos (opioides y no opioides), hipnóticos y relajantes neuromusculares, de uso habitual, que pueden tener interés para el médico de Urgencias (hospitalarias y no hospitalarias) y dirigido a estos profesionales .Se describen aquellos principios activos con un perfil farmacocinético y farmacodinámico más acorde con el manejo agudo de los pacientes en estas unidades, sin profundizar demasiado en otros aspectos derivados de su aplicación a largo plazo.-Hipnóticos, habitualmente empleados como inductores anestésicos y que se caracterizan por provocar la inconsciencia de forma predecible y con recuperación rápida. Pertenecen a este grupo el tiopental, propofol, etomidato y ketamina.-Benzodiacepinas, dentro de este grupo se revisan los dos fármacos con mayores posibilidades de administración parenteral para el control agudo de la situación. Se trata del diacepam y del midazolam. El espectro de acciones de estas benzodiacepinas varía en función de la dosis y va de la ansiolisis a la hipnosis pasando por la sedación, amnesia y actividad anticonvulsivante.-Opiáceos, son analgésicos potentes que interactúan a través de los receptores opioides ampliamente distribuidos por el organismo. Morfina, meperidina, fentanilo, alfentanilo y tramadol pertecen a este grupo. Los analgésicos no opoides: ketorolaco, metamizol y propacetamol, tienen sus indicaciones y habitualmente se administran en asociación con los anteriores .-Bloqueantes neurmusculares: son inhibidores de la transmisión sináptica en la unión neuromuscular, suprimiendo toda la actividad contráctil de la musculatura estriada. Se clasifican en dos tipos en función del mecanismo de acción: -BM despolarizantes: succinilcolina -BM no despolarizantes: atracurio, vecuronio y rocuronio entre otros .Por último se incluyen una serie de recomendaciones prácticas de sedoanalgesia y relajación neuromuscular, según el estado hemodinámico, patología cardiaca concomitante, función ventilatoria y situación neurológica inicial del paciente en el momento de su llegada al Hospital (AU)

[Effect of catalase on acute experimental pancreatitis in rats]. / Efecto de la catalasa en la pancreatitis aguda experimental de la rata.

Oxygen free radicals are highly toxic end products of the cellular oxidative metabolism that are scavenged by antioxidative systems such as superoxide dismutase and catalase. Previous studies have suggested that oxygen free radicals may play a role in the pathophysiology of acute pancreatitis. The present study was designed to determine the effect of catalase on experimental acute pancreatitis in the rat. Rats were given either saline or enterokinase by the intraductal pancreatic route. Catalase was given intraperitoneally at doses of 80, 160 and 320 mg/kg. Administration of saline resulted in mild acute pancreatitis. In contrast, administration of enterokinase resulted in oedema, haemorrhage and necrosis of the pancreas. Catalase had no effect when given at 80 mg/kg; at 160 mg/kg, an improvement at the ultrastructural level was noted, whereas at 320 mg/kg, a change in serum calcium level was found. Our studies suggest that intraperitoneal administration of catalase slightly improves the outcome of experimental acute pancreatitis in the rat.