Pelagic bacterial communities across the Arctic-Atlantic boundary zone

In recent decades, the Eurasian Basin of the Arctic Ocean has undergone remarkable variations as part of the large-scale environmental changes facing the planet. The Fram Strait connects the Arctic Ocean to the North Atlantic, and provides the main gateway for water exchange between the Arctic and the global oceans. Two major current systems are present in Fram Strait: the West Spitsbergen Current (WSC) carries Atlantic water northwards, and the East Greenland Current (EGC) brings cold Arctic waters and ice southwards (Fig 1 and 2). The proximity of these two distinct current systems creates a valuable opportunity for studying differences in microbial community composition across strong gradients of temperature and ice cover. Here we present a first preliminary investigation of both free-living and particle-associated pelagic bacterial communities in the upper water column across a longitudinal transect of the entire Fram Strait, conducted during RV Polarstern expedition PS85 (ARK-XXVIII/2) in June 2014

CT-guided percutaneous drilling is a safe and reliable method of treating osteoid osteomas

Computed tomography (CT)-guided percutaneous drilling is an alternative for osteoid osteoma treatment. This study aims to evaluate the remodeling of the drill orifice. The success rate and complications were also recorded and compared with other treatment methods. Fifteen patients with an average age of fourteen years (ranging from 4 to 25) submitted to CT-guided percutaneous drilling between 2003 and 2009 were retrospectively analyzed according to clinical and radiological criteria. Fourteen cases showed complete alleviation of pain one week after surgery. No relapse was detected even in the subject who continued complaining of pain. All patients were treated with a day-hospital regimen and were discharged with partial weight bearing. Total weight bearing was allowed after one month, and sports were allowed after consolidation, which occurred in all but one case after the third month. One patient, who did not follow our medical advice, returned to sports activities after two weeks and experienced a fracture as a result. Atrophy of the vastus lateralis muscle developed after the procedure in another patient. Our case series suggests that this method is reliable and safe. The level of complexity is comparable with other minimally invasive percutaneous procedures. The cost is low because there is no need to buy probes or other equipment. The negative points include weakening of the bone and the logistical problem of assembling the orthopedic surgeon, radiologist, and anesthesiologist in the tomography room

Osteointegration of porous absorbable bone substitutes: A systematic review of the literature

Biomaterials’ structural characteristics and the addition of osteoinductors influence the osteointegration capacity of bone substitutes. This study aims to identify the characteristics of porous and resorbable bone substitutes that influence new bone formation. An Internet search for studies reporting new bone formation rates in bone defects filled with porous and resorbable substitutes was performed in duplicate using the PubMed, Web of Science, Scielo, and University of São Paulo Digital Library databases. Metaphyseal or calvarial bone defects 4 to 10 mm in diameter from various animal models were selected. New bone formation rates were collected from the histomorphometry or micro-CT data. The following variables were analyzed: animal model, bone region, defect diameter, follow-up time after implantation, basic substitute material, osteoinductor addition, pore size and porosity. Of 3,266 initially identified articles, 15 articles describing 32 experimental groups met the inclusion criteria. There were no differences between the groups in the experimental model characteristics, except for the follow-up time, which showed a very weak to moderate correlation with the rate of new bone formation. In terms of the biomaterial and structural characteristics, only porosity showed a significant influence on the rate of new bone formation. Higher porosity is related to higher new bone formation rates. The influence of other characteristics could not be identified, possibly due to the large variety of experimental models and methodologies used to estimate new bone formation rates. We suggest the inclusion of standard control groups in future experimental studies to compare biomaterials

CT-guided percutaneous drilling is a safe and reliable method of treating osteoid osteomas

Computed tomography (CT)-guided percutaneous drilling is an alternative for osteoid osteoma treatment. This study aims to evaluate the remodeling of the drill orifice. The success rate and complications were also recorded and compared with other treatment methods

Summertime plankton ecology in Fram Strait - a compilation of long- and short-term observations

Between Greenland and Spitsbergen, Fram Strait is a region where cold ice-covered Polar Water exits the Arctic Ocean with the East Greenland Current (EGC) and warm Atlantic Water enters the Arctic Ocean with the West Spitsbergen Current (WSC). In this compilation, we present two different data sets from plankton ecological observations in Fram Strait: (1) long-term measurements of satellite-derived (1998–2012) and in situ chlorophyll a (chl a) measurements (mainly summer cruises, 1991–2012) plus protist compositions (a station in WSC, eight summer cruises, 1998–2011); and (2) short-term measurements of a multidisciplinary approach that includes traditional plankton investigations, remote sensing, zooplankton, microbiological and molecular studies, and biogeochemical analyses carried out during two expeditions in June/July in the years 2010 and 2011. Both summer satellite-derived and in situ chl a concentrations showed slight trends towards higher values in the WSC since 1998 and 1991, respectively. In contrast, no trends were visible in the EGC. The protist composition in the WSC showed differences for the summer months: a dominance of diatoms was replaced by a dominance of Phaeocystis pouchetii and other small pico- and nanoplankton species. The observed differences in eastern Fram Strait were partially due to a warm anomaly in the WSC. Although changes associated with warmer water temperatures were observed, further long-term investigations are needed to distinguish between natural variability and climate change in Fram Strait. Results of two summer studies in 2010 and 2011 revealed the variability in plankton ecology in Fram Strait

Microbial Communities in the East and West Fram Strait During Sea Ice Melting Season

Climate models project that the Arctic Ocean may experience ice-free summers by the second half of this century. This may have severe repercussions on phytoplankton bloom dynamics and the associated cycling of carbon in surface waters. We currently lack baseline knowledge of the seasonal dynamics of Arctic microbial communities, which is needed in order to better estimate the effects of such changes on ecosystem functioning. Here we present a comparative study of polar summer microbial communities in the ice-free (eastern) and ice-covered (western) hydrographic regimes at the LTER HAUSGARTEN in Fram Strait, the main gateway between the Arctic and North Atlantic Oceans. Based on measured and modeled biogeochemical parameters, we tentatively identified two different ecosystem states (i.e., different phytoplankton bloom stages) in the distinct regions. Using Illumina tag-sequencing, we determined the community composition of both free-living and particle-associated bacteria as well as microbial eukaryotes in the photic layer. Despite substantial horizontal mixing by eddies in Fram Strait, pelagic microbial communities showed distinct differences between the two regimes, with a proposed early spring (pre-bloom) community in the ice-covered western regime (with higher representation of SAR11, SAR202, SAR406 and eukaryotic MALVs) and a community indicative of late summer conditions (post-bloom) in the ice-free eastern regime (with higher representation of Flavobacteria, Gammaproteobacteria and eukaryotic heterotrophs). Co-occurrence networks revealed specific taxon-taxon associations between bacterial and eukaryotic taxa in the two regions. Our results suggest that the predicted changes in sea ice cover and phytoplankton bloom dynamics will have a strong impact on bacterial community dynamics and potentially on biogeochemical cycles in this region

Microbial Communities in the East and West Fram Strait During Sea Ice Melting Season

Climate models project that the Arctic Ocean may experience ice-free summers by the second half of this century. This may have severe repercussions on phytoplankton bloom dynamics and the associated cycling of carbon in surface waters. We currently lack baseline knowledge of the seasonal dynamics of Arctic microbial communities, which is needed in order to better estimate the effects of such changes on ecosystem functioning. Here we present a comparative study of polar summer microbial communities in the ice-free (eastern) and ice-covered (western) hydrographic regimes at the LTER HAUSGARTEN in Fram Strait, the main gateway between the Arctic and North Atlantic Oceans. Based on measured and modeled biogeochemical parameters, we tentatively identified two different ecosystem states (i.e., different phytoplankton bloom stages) in the distinct regions. Using Illumina tag-sequencing, we determined the community composition of both free-living and particle-associated bacteria as well as microbial eukaryotes in the photic layer. Despite substantial horizontal mixing by eddies in Fram Strait, pelagic microbial communities showed distinct differences between the two regimes, with a proposed early spring (pre-bloom) community in the ice-covered western regime (with higher representation of SAR11, SAR202, SAR406 and eukaryotic MALVs) and a community indicative of late summer conditions (post-bloom) in the ice-free eastern regime (with higher representation of Flavobacteria, Gammaproteobacteria and eukaryotic heterotrophs). Co-occurrence networks revealed specific taxon-taxon associations between bacterial and eukaryotic taxa in the two regions. Our results suggest that the predicted changes in sea ice cover and phytoplankton bloom dynamics will have a strong impact on bacterial community dynamics and potentially on biogeochemical cycles in this region