A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3

The element abundance ratios of four low-mass stars with extremely low metallicities indicate that the gas out of which the stars formed was enriched in each case by at most a few, and potentially only one low-energy, supernova. Such supernovae yield large quantities of light elements such as carbon but very little iron. The dominance of low-energy supernovae is surprising, because it has been expected that the first stars were extremely massive, and that they disintegrated in pair-instability explosions that would rapidly enrich galaxies in iron. What has remained unclear is the yield of iron from the first supernovae, because hitherto no star is unambiguously interpreted as encapsulating the yield of a single supernova. Here we report the optical spectrum of SMSS J031300.36- 670839.3, which shows no evidence of iron (with an upper limit of 10^-7.1 times solar abundance). Based on a comparison of its abundance pattern with those of models, we conclude that the star was seeded with material from a single supernova with an original mass of ~60 Mo (and that the supernova left behind a black hole). Taken together with the previously mentioned low-metallicity stars, we conclude that low-energy supernovae were common in the early Universe, and that such supernovae yield light element enrichment with insignificant iron. Reduced stellar feedback both chemically and mechanically from low-energy supernovae would have enabled first-generation stars to form over an extended period. We speculate that such stars may perhaps have had an important role in the epoch of cosmic reionization and the chemical evolution of early galaxies.Comment: 28 pages, 6 figures, Natur

A rigid barrier between the heart and sternum protects the heart and lungs against rupture during negative pressure wound therapy

<p>Abstract</p> <p>Objectives</p> <p>Right ventricular heart rupture is a devastating complication associated with negative pressure wound therapy (NPWT) in cardiac surgery. The use of a rigid barrier has been suggested to offer protection against this lethal complication, by preventing the heart from being drawn up and damaged by the sharp edges of the sternum. The aim of the present study was to investigate whether a rigid barrier protects the heart and lungs against injury during NPWT.</p> <p>Methods</p> <p>Sixteen pigs underwent median sternotomy followed by NPWT at -120 mmHg for 24 hours, in the absence (eight pigs) or presence (eight pigs) of a rigid plastic disc between the heart and the sternal edges. The macroscopic appearance of the heart and lungs was inspected after 12 and 24 hours of NPWT.</p> <p>Results</p> <p>After 24 hours of NPWT at -120 mmHg the area of epicardial petechial bleeding was 11.90 ± 1.10 cm²when no protective disc was used, and 1.15 ± 0.19 cm²when using the disc (p < 0.001). Heart rupture was observed in three of the eight animals treated with NPWT without the disc. Lung rupture was observed in two of the animals, and lung contusion and emphysema were seen in all animals treated with NPWT without the rigid disc. No injury to the heart or lungs was observed in the group of animals treated with NPWT using the rigid disc.</p> <p>Conclusion</p> <p>Inserting a rigid barrier between the heart and the sternum edges offers protection against heart rupture and lung injury during NPWT.</p

Elucidation of the controlled-release behavior of metoprolol succinate from directly compressed xanthan gum-chitosan polymers: computational and experimental studies

The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comprising xanthan gum (XG), low molecular weight chitosan (LCS) and metoprolol succinate (MS) is reported. The research is, partly, based upon the utilization of computational tools; in this case molecular dynamics simulations (MDs) and response surface method (RSM), in order to underpin the design/prediction and to minimize the experimental work required to achieve the desired pharmaceutical outcomes. The capability of the system to control the release of MS was studied as a function of LCS (% w/w) and total polymer (LCS and XG) to drug ratio (P:D) at different tablet tensile strengths. MDs trajectories, obtained by using different ratios of XG:LCS as well as XG and high molecular weight CS (HCS), showed that the driving force for the interaction between XG and LCS is electrostatic in nature, the most favourable complex is formed when LCS is used at 15 % (w/w) and, importantly, that the interaction between XG and LCS is more favourable than that between XG and HCS. RSM outputs revealed that the release of the drug from the LCS/XG matrix is highly dependent on both the % LCS and the P:D ratio and that the required CR effect can be achieved when using weight fractions of LCS ≤ 20% and P:D ratios ≥ 2.6:1. Results obtained from in-vitro drug release and swelling studies on the prepared tablets showed that using LCS at the weight fractions suggested by MDs and RSM data plays a major role in overcoming the high sensitivity of the controlled drug release effect of XG on ionic strength and pH changes of the dissolution media. In addition, it was found that polymer relaxation is the major contributor to the release of MS from LCS-XG tablets. Using Raman spectroscopy, MS was shown to be localized more in the core of the tablets at the initial stages of dissolution due to film formation between LCS and XG on the tablet surface which prevents excess water penetration into the matrix. In the later stages of the dissolution process, the film starts to dissolve/erode allowing full tablet hydration and a uniform drug distribution in the swollen tablet

Case report: The management of advanced oral cancer in a Jehovah's Witness using the Ultracision Harmonic Scalpel

We present the first case of a head and neck oncological procedure accomplished in a Jehovah's Witness using the Ultracision Harmonic Scalpel (Ethicon, Cincinnati, OH). Jehovah's Witnesses present a serious challenge to the head and neck cancer surgeon due to their refusal to accept transfusion of any blood products. However, our experience reinforces the view that surgical management of head and neck cancer is possible in these patients. We show the Harmonic Scalpel, an ultrasonic tissue dissector, to be a useful surgical tool in obviating the need for blood transfusion. Preoperative optimisation, intra-operative surgical and anaesthetic techniques are also fully discussed

Multi tyrosine kinase inhibitor dasatinib as novel cause of severe pre-capillary pulmonary hypertension?

<p>Abstract</p> <p>Background</p> <p>Pulmonary hypertension (PH) is a life-threatening disease with poor prognosis. Encouraging efforts have been made to target the main vasoproliferative aspects of the disease. Promising emerging therapeutics are tyrosine kinase inhibitors such as imatinib.</p> <p>Case presentation</p> <p>Here, we discuss the relevance of previously published cases and add another well-characterised patient who developed pre-capillary PH under long-term therapy with the multi-tyrosine kinase inhibitor dasatinib approved for therapy of chronic myeloic leukaemia (CML) and Philadelphia chromosome positive acute lymphocytic leukaemia (mean time of all patients on dasatinib: 26 months). Hence, we discuss the possibility of dasatinib itself causing PH after long-term therapy and turn specialist's attention to this possible severe side effect.</p> <p>At present, the true incidence of dasatinib-associated PH remains illusive and systematic data regarding haemodynamics are missing.</p> <p>Conclusion</p> <p>We therefore recommend systematic screening of dasatinib-treated patients for pulmonary hypertension and subsequent collection of haemodynamic data.</p

Radiation dose reduction at a price: the effectiveness of a male gonadal shield during helical CT scans

BACKGROUND: It is estimated that 60 million computed tomography (CT) scans were performed during 2006, with approximately 11% of those performed on children age 0–15 years. Various types of gonadal shielding have been evaluated for reducing exposure to the gonads. The purpose of this study was to quantify the radiation dose reduction to the gonads and its effect on image quality when a wrap-around male pediatric gonad shield was used during CT scanning. This information is obtained to assist the attending radiologist in the decision to utilize such male gonadal shields in pediatric imaging practice. METHODS: The dose reduction to the gonads was measured for both direct radiation and for indirect scattered radiation from the abdomen. A 6 cm(3 )ion chamber (Model 10X5-6, Radcal Corporation, Monrovia, CA) was placed on a Humanoid real bone pelvic phantom at a position of the male gonads. When exposure measurements with shielding were made, a 1 mm lead wrap-around gonadal shield was placed around the ion chamber sensitive volume. RESULTS: The use of the shields reduced scatter dose to the gonads by a factor of about 2 with no appreciable loss of image quality. The shields reduced the direct beam dose by a factor of about 35 at the expense of extremely poor CT image quality due to severe streak artifacts. CONCLUSION: Images in the direct exposure case are not useful due to these severe artifacts and the difficulties in positioning these shields on patients in the scatter exposure case may not be warranted by the small absolute reduction in scatter dose unless it is expected that the patient will be subjected to numerous future CT scans

Bacterial cellulose-lactoferrin as an antimicrobial edible packaging

Bacterial cellulose (BC) films from two distinct sources (obtained by static culture with Gluconacetobacter xylinus ATCC 53582 (BC1) and from a commercial source (BC2)) were modified by bovine lactoferrin (bLF) adsorption. The functionalized films (BC+bLF) were assessed as edible antimicrobial packaging, for use in direct contact with highly perishable foods, specifically fresh sausage as a model of meat products. BC+bLF films and sausage casings were characterized regarding their water vapour permeability (WVP), mechanical properties, and bactericidal efficiency against two food pathogens, Escherichia coli and Staphylococcus aureus. Considering their edibility, an in vitro gastrointestinal tract model was used to study the changes occurring in the BC films during passage through the gastrointestinal tract. Moreover, the cytotoxicity of the BC films against 3T3 mouse embryo fibroblasts was evaluated. BC1 and BC2 showed equivalent density, WVP and maximum tensile strength. The percentage of bactericidal efficiency of BC1 and BC2 with adsorbed bLF (BC1+bLF and BC2+bLF, respectively) in the standalone films and in inoculated fresh sausages, was similar against E. coli (mean reduction 69 % in the films per se versus 94 % in the sausages) and S. aureus (mean reduction 97 % in the films per se versus 36 % in the case sausages). Moreover, the BC1+bLF and BC2+bLF films significantly hindered the specific growth rate of both bacteria. Finally, no relevant cytotoxicity against 3T3 fibroblasts was found for the films before and after the simulated digestion. BC films with adsorbed bLF may constitute an approach in the development of bio-based edible antimicrobial packaging systems.The authors would like to acknowledge Portuguese Foundation for Science and Technology (Fundação para a Ciência e Tecnologia) for the research grants: Jorge Padrão SFRH/BD/64901/2009, Sara Gonçalves SFRH/BD/63578/2009, João Pedro Silva SFRH/BPD/ 64958/2009, Ana Cristina Pinheiro SFRH/BPD/101181/2014. V. Sencadas thanks support from the COST Action MP1206: “Electrospun nano-fibres for bio inspired composite materials and innovative industrial applications” and MP1301: “New Generation Biomimetic and Customized Implants for Bone Engineering”. The authors would also like to thank the co-funded by the Programa Operacional Regional do Norte (ON.2 e O Novo Norte), QREN, FEDER Projects “BioHealth e Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124- FEDER-000027; “BioInd e Biotechnology and Bioengineering for improved Industrial and Agro-Food processes”, REF. NORTE-07- 0124-FEDER-000028; Strategic Project PEST-C/FIS/UI607/2014; Matepro eOptimizing Materials and Processes”, ref. NORTE-07- 0124-FEDER-000037; Strategic Project PEst-OE/EQB/LA0023/2013 and project ref. RECI/BBB-EBI/0179/2012 (project number FCOMP- 01-0124-FEDER-027462). Finally, the authors thank the Fundação para a Ciência e Tecnologia for the strategic funding from the UID/ BIO/04469/2013 unit

Ethics, economics and the regulation and adoption of new medical devices: case studies in pelvic floor surgery

<p>Abstract</p> <p>Background</p> <p>Concern has been growing in the academic literature and popular media about the licensing, introduction and adoption of surgical devices before full effectiveness and safety evidence is available to inform clinical practice. Our research will seek empirical survey evidence about the roles, responsibilities, and information and policy needs of the key stakeholders in the introduction into clinical practice of new surgical devices for pelvic floor surgery, in terms of the underlying ethical principals involved in the economic decision-making process, using the example of pelvic floor procedures.</p> <p>Methods/Design</p> <p>Our study involves three linked case studies using, as examples, selected pelvic floor surgery devices representing Health Canada device safety risk classes: low, medium and high risk. Data collection will focus on stakeholder roles and responsibilities, information and policy needs, and perceptions of those of other key stakeholders, in seeking and using evidence about new surgical devices when licensing and adopting them into practice. For each class of device, interviews will be used to seek the opinions of stakeholders. The following stakeholders and ethical and economic principles provide the theoretical framework for the study:</p> <p indent="1"><b>Stakeholders </b>- federal regulatory body, device manufacturers, clinicians, patients, health care institutions, provincial health departments, and professional societies. Clinical settings in two centres (in different provinces) will be included.</p> <p indent="1"><b>Ethics </b>- beneficence, non-maleficence, autonomy, justice.</p> <p indent="1"><b>Economics </b>- scarcity of resources, choices, opportunity costs.</p> <p>For each class of device, responses will be analysed to compare and contrast between stakeholders. Applied ethics and economic theory, analysis and critical interpretation will be used to further illuminate the case study material.</p> <p>Discussion</p> <p>The significance of our research in this new area of ethics will lie in providing recommendations for regulatory bodies, device manufacturers, clinicians, health care institutions, policy makers and professional societies, to ensure surgical patients receive sufficient information before providing consent for pelvic floor surgery. In addition, we shall provide a wealth of information for future study in other areas of surgery and clinical management, and provide suggestions for changes to health policy.</p

Can houseplants improve indoor air quality by removing CO2 and increasing relative humidity?

High indoor CO2 concentrations and low relative humidity (RH) create an array of well-documented human health issues. Therefore, assessing houseplants’ potential as a low-cost approach to CO2 removal and increasing RH is important. We investigated how environmental factors such as ’dry’ ( 0.30 m3 m-3) growing substrates, and indoor light levels (‘low’ 10 µmol m-2 s-1, ‘high’ 50 µmol m-2 s-1 and ‘very high’ 300 µmol m-2 s-1), influence the plants’ net CO2 assimilation (‘A’) and water-vapour loss. Seven common houseplant taxa – representing a variety of leaf types, metabolisms and sizes – were studied for their ability to assimilate CO2 across a range of indoor light levels. Additionally, to assess the plants’ potential contribution to RH increase, the plants’ evapo-transpiration (ET) was measured. At typical ‘low’ indoor light levels ‘A’ rates were generally low (< 3.9 mg hr-1). Differences between ‘dry’ and ’wet’ plants at typical indoor light levels were negligible in terms of room-level impact. Light compensation points (i.e. light levels at which plants have positive ‘A’) were in the typical indoor light range (1-50 µmol m-2 s-1) only for two studied Spathiphyllum wallisii cultivars and Hedera helix; these plants would thus provide the best CO2 removal indoors. Additionally, increasing indoor light levels to 300 µmol m-2 s-1 would, in most species, significantly increase their potential to assimilate CO2. Species which assimilated the most CO2 also contributed most to increasing RH