The electric wind of Venus: A global and persistent "polar wind"-like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions

Understanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an “ambipolar” electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water-group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an “electric wind” must be considered when studying the evolution and potential habitability of any planet in any star system

Nitrogen uptake and internal recycling in Zostera marina exposed to oyster farming: eelgrass potential as a natural biofilter

Oyster farming in estuaries and coastal lagoons frequently overlaps with the distribution of seagrass meadows, yet there are few studies on how this aquaculture practice affects seagrass physiology. We compared in situ nitrogen uptake and the productivity of Zostera marina shoots growing near off-bottom longlines and at a site not affected by oyster farming in San Quintin Bay, a coastal lagoon in Baja California, Mexico. We used benthic chambers to measure leaf NH4 (+) uptake capacities by pulse labeling with (NH4)-N-15 (+) and plant photosynthesis and respiration. The internal N-15 resorption/recycling was measured in shoots 2 weeks after incubations. The natural isotopic composition of eelgrass tissues and vegetative descriptors were also examined. Plants growing at the oyster farming site showed a higher leaf NH4 (+) uptake rate (33.1 mmol NH4 (+) m(-2) day(-1)) relative to those not exposed to oyster cultures (25.6 mmol NH4 (+) m(-2) day(-1)). We calculated that an eelgrass meadow of 15-16 ha (which represents only about 3-4 % of the subtidal eelgrass meadow cover in the western arm of the lagoon) can potentially incorporate the total amount of NH4 (+) excreted by oysters (similar to 5.2 x 10(6) mmol NH4 (+) day(-1)). This highlights the potential of eelgrass to act as a natural biofilter for the NH4 (+) produced by oyster farming. Shoots exposed to oysters were more efficient in re-utilizing the internal N-15 into the growth of new leaf tissues or to translocate it to belowground tissues. Photosynthetic rates were greater in shoots exposed to oysters, which is consistent with higher NH4 (+) uptake and less negative delta C-13 values. Vegetative production (shoot size, leaf growth) was also higher in these shoots. Aboveground/belowground biomass ratio was lower in eelgrass beds not directly influenced by oyster farms, likely related to the higher investment in belowground biomass to incorporate sedimentary nutrients

In vitro susceptibility to pyrimethamine of DHFR I164L single mutant Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>Recently, <it>Plasmodium falciparum </it>parasites bearing <it>Pfdhfr </it>I164L single mutation were found in Madagascar. These new mutants may challenge the use of antifolates for the intermittent preventive treatment of malaria during pregnancy (IPTp). Assays with transgenic bacteria suggested that I164L parasites have a wild-type phenotype for pyrimethamine but it had to be confirmed by testing the parasites themselves.</p> <p>Methods</p> <p>Thirty <it>Plasmodium falciparum </it>clinical isolates were collected in 2008 in the south-east of Madagascar. A part of <it>Pfdhfr </it>gene encompassing codons 6 to 206 was amplified by PCR and the determination of the presence of single nucleotide polymorphisms was performed by DNA sequencing. The multiplicity of infection was estimated by using an allelic family-specific nested PCR. Isolates that appeared monoclonal were submitted to culture adaptation. Determination of IC_50sto pyrimethamine was performed on adapted isolates.</p> <p>Results</p> <p>Four different <it>Pfdhfr </it>alleles were found: the 164L single mutant-type (N = 13), the wild-type (N = 7), the triple mutant-type 51I/59R/108N (N = 9) and the double mutant-type 108N/164L (N = 1). Eleven out 30 (36.7%) of <it>P. falciparum </it>isolates were considered as monoclonal infection. Among them, five isolates were successfully adapted in culture and tested for pyrimethamine <it>in vitro </it>susceptibility. The wild-type allele was the most susceptible with a 50% inhibitory concentration (IC₅₀) < 10 nM. The geometric mean of IC₅₀of the three I164L mutant isolates was 6-fold higher than the wild-type with 61.3 nM (SD = 3.2 nM, CI95%: 53.9-69.7 nM). These values remained largely below the IC₅₀of the triple mutant parasite (13,804 nM).</p> <p>Conclusion</p> <p>The IC₅₀s of the I164L mutant isolates were significantly higher than those of the wild-type (6-fold higher) and close from those usually reported for simple mutants S108N (roughly10-fold higher than wild type). Given the observed values, the determination of IC₅₀s directly on parasites did not confirm what has been found on transgenic bacteria. The prevalence increase of the <it>Pfdhfr </it>I164L single mutant parasite since 2006 could be explained by the selective advantage of this allele under sulphadoxine-pyrimethamine pressure. The emergence of highly resistant alleles should be considered in the future, in particular because an unexpected double mutant-type allele S108N/I164L has been already detected.</p

Imaging features of foreign body granuloma in the lower extremities mimicking a soft tissue neoplasm

Foreign body granuloma is a tissue reaction for retained foreign bodies after skin-penetrating trauma. Detection of retained foreign bodies can be extremely difficult when the patients present with non-specific symptoms such as pain and/or swelling without recognizing a previous trauma. We report three patients of foreign body granulomas in the lower extremities with emphasis placed on their unique clinical and radiological features. The involved sites were the foot, posterior thigh, and posterior lower leg, with wooden splinters in two patients and a fragment of tile in one. Plain radiographs could not reveal the existence of foreign bodies. Magnetic resonance imaging (MRI) showed foreign bodies as low intensities on both T1- and T2-weighted images in two patients, and the surrounding reactive lesion as low to iso intensities on T1- and high intensities on T2-weighted images in all the patients. The peripheral areas of the lesion were strongly enhanced after gadolinium injection. Ultrasound sonography could clearly visualize a foreign body as an echogenic area with posterior acoustic shadowing in one patient. The surrounding ring-like reactive lesion is easily mistaken for a soft tissue neoplasm when foreign bodies are not identified. The key to arriving at the correct diagnosis is to clarify the previous trauma and to identify foreign bodies with low signal intensities on both T1- and T2-weighted images and/or the characteristic ring-like enhancement on MRI. It is also necessary to rule out a foreign body granuloma whenever we see patients with a soft tissue tumor in the extremities, irrespective of their previous trauma history

Concerns about the use of polygenic embryo screening for psychiatric and cognitive traits

Private companies have begun offering services to allow parents undergoing in-vitro fertilisation to screen embryos for genetic risk of complex diseases, including psychiatric disorders. This procedure, called polygenic embryo screening, raises several difficult scientific and ethical issues, as discussed in this Personal View. Polygenic embryo screening depends on the statistical properties of polygenic risk scores, which are complex and not well studied in the context of this proposed clinical application. The clinical, social, and ethical implications of polygenic embryo screening have barely been discussed among relevant stakeholders. To our knowledge, the International Society of Psychiatric Genetics is the first professional biomedical organisation to issue a statement regarding polygenic embryo screening. For the reasons discussed in this Personal View, the Society urges caution and calls for additional research and oversight on the use of polygenic embryo screening

Implementation and evaluation of a multisite drug usage evaluation program across Australian hospitals - a quality improvement initiative

Background: With the use of medicines being a broad and extensive part of health management, mechanisms to ensure quality use of medicines are essential. Drug usage evaluation (DUE) is an evidence-based quality improvement methodology, designed to improve the quality, safety and cost-effectiveness of drug use. The purpose of this paper is to describe a national DUE methodology used to improve health care delivery across the continuum through multi-faceted intervention involving audit and feedback, academic detailing and system change, and a qualitative assessment of the methodology, as illustrated by the Acute Postoperative Pain Management (APOP) project. Methods. An established methodology, consisting of a baseline audit of inpatient medical records, structured patient interviews and general practitioner surveys, followed by an educational intervention and follow-up audit, is used. Australian hospitals, including private, public, metropolitan and regional, are invited to participate on a voluntary basis. De-identified data collected by hospitals are collated and evaluated nationally to provide descriptive comparative analyses. Hospitals benchmark their practices against state and national results to facilitate change. The educational intervention consists of academic detailing, group education, audit and feedback, point-of-prescribing prompts and system changes. A repeat data collection is undertaken to assess changes in practice. An online qualitative survey was undertaken to evaluate the APOP program. Qualitative assessment of hospitals' perceptions of the effectiveness of the overall DUE methodology and changes in procedure/prescribing/policy/clinical practice which resulted from participation were elicited. Results: 62 hospitals participated in the APOP project. Among 23 respondents to the evaluation survey, 18 (78%) reported improvements in the documentation of pain scores at their hospital. 15 (65%) strongly agreed or agreed that participation in APOP directly resulted in increased prescribing of multimodal analgesia for pain relief in postoperative patients. Conclusions: This national DUE program has facilitated the engagement and participation of a number of acute health care facilities to address issues relating to quality use of medicine. This approach has been perceived to be effective in helping them achieve improvements in patient care

A Controlled Investigation of Optimal Internal Medicine Ward Team Structure at a Teaching Hospital

BACKGROUND: The optimal structure of an internal medicine ward team at a teaching hospital is unknown. We hypothesized that increasing the ratio of attendings to housestaff would result in an enhanced perceived educational experience for residents. METHODS: Harbor-UCLA Medical Center (HUMC) is a tertiary care, public hospital in Los Angeles County. Standard ward teams at HUMC, with a housestaff∶attending ratio of 5:1, were split by adding one attending and then dividing the teams into two experimental teams containing ratios of 3:1 and 2:1. Web-based Likert satisfaction surveys were completed by housestaff and attending physicians on the experimental and control teams at the end of their rotations, and objective healthcare outcomes (e.g., length of stay, hospital readmission, mortality) were compared. RESULTS: Nine hundred and ninety patients were admitted to the standard control teams and 184 were admitted to the experimental teams (81 to the one-intern team and 103 to the two-intern team). Patients admitted to the experimental and control teams had similar age and disease severity. Residents and attending physicians consistently indicated that the quality of the educational experience, time spent teaching, time devoted to patient care, and quality of life were superior on the experimental teams. Objective healthcare outcomes did not differ between experimental and control teams. CONCLUSIONS: Altering internal medicine ward team structure to reduce the ratio of housestaff to attending physicians improved the perceived educational experience without altering objective healthcare outcomes

Surface plasmon resonance imaging of cells and surface-associated fibronectin

<p>Abstract</p> <p>Background</p> <p>A critical challenge in cell biology is quantifying the interactions of cells with their extracellular matrix (ECM) environment and the active remodeling by cells of their ECM. Fluorescence microscopy is a commonly employed technique for examining cell-matrix interactions. A label-free imaging method would provide an alternative that would eliminate the requirement of transfected cells and modified biological molecules, and if collected nondestructively, would allow long term observation and analysis of live cells.</p> <p>Results</p> <p>Using surface plasmon resonance imaging (SPRI), the deposition of protein by vascular smooth muscle cells (vSMC) cultured on fibronectin was quantified as a function of cell density and distance from the cell periphery. We observed that as much as 120 ng/cm²of protein was deposited by cells in 24 h.</p> <p>Conclusion</p> <p>SPRI is a real-time, low-light-level, label-free imaging technique that allows the simultaneous observation and quantification of protein layers and cellular features. This technique is compatible with live cells such that it is possible to monitor cellular modifications to the extracellular matrix in real-time.</p

Marsh macrophyte responses to inundation anticipate impacts of sea-level rise and indicate ongoing drowning of North Carolina marshes

In situ persistence of coastal marsh habitat as sea level rises depends on whether macrophytes induce compensatory accretion of the marsh surface. Experimental planters in two North Carolina marshes served to expose two dominant macrophyte species to six different elevations spanning 0.75 m (inundation durations 0.4–99 %). Spartina alterniflora and Juncus roemerianus exhibited similar responses—with production in planters suggesting initial increases and then demonstrating subsequent steep declines with increasing inundation, conforming to a segment of the ecophysiological parabola. Projecting inundation levels experienced by macrophytes in the planters onto adjacent marsh platforms revealed that neither species occupied elevations associated with increasing production. Declining macrophyte production with rising seas reduces both bioaccumulation of roots below-ground and baffle-induced sedimentation above-ground. By occupying only descending portions of the parabola, macrophytes in central North Carolina marshes are responding to rising water levels by progressive declines in production, ultimately leading to marsh drowning

FISH and DAPI staining of the synaptonemal complex of the Nile tilapia (Oreochromis niloticus) allow orientation of the unpaired region of bivalent 1 observed during early pachytene

Bivalent 1 of the synaptonemal complex (SC) in XY male Oreochromis niloticus shows an unpaired terminal region in early pachytene. This appears to be related to recombination suppression around a sex determination locus. To allow more detailed analysis of this, and unpaired regions in the karyotype of other Oreochromis species, we developed techniques for FISH on SC preparations, combined with DAPI staining. DAPI staining identified presumptive centromeres in SC bivalents, which appeared to correspond to the positions observed in the mitotic karyotype (the kinetochores could only be identified sporadically in silver stained EM SC images). Furthermore, two BAC clones containing Dmo (dmrt4) and OniY227 markers that hybridize to known positions in chromosome pair 1 in mitotic spreads (near the centromere, FLpter 0.25, and the putative sex determination locus, FLpter 0.57, respectively) were used as FISH probes on SCs to verify that the presumptive centromere identified by DAPI staining was located in the expected position. Visualization of both the centromere and FISH signals on bivalent 1 allowed the unpaired region to be positioned at Flpter 0.80 to 1.00, demonstrating that the unpaired region is located in the distal part of the long arm(s). Finally, differences between mitotic and meiotic measurements are discussed