436 research outputs found
Participation in environmental health research by placenta donation – a perception study
<p>Abstract</p> <p>Background</p> <p>Much environmental health research depends on human volunteers participating with biological samples. The perception study explores why and how people participate in a placenta perfusion study in Copenhagen. The participation implies donation of the placenta after birth and some background information but no follow up.</p> <p>Methods</p> <p>Nineteen semi-structured qualitative interviews were conducted with participants in the placenta perfusion study after donation of placenta. Observation studies were made of recruitment sessions.</p> <p>Results</p> <p>The interviewed participants are generally in favour of medical research. They participated in the placenta perfusion study due to a belief that societal progress follows medical research. They also felt that participating was a way of giving something back to the Danish health care system. The participants have trust in medical science and scientists, but trust is something which needs to be created through "trust-work". Face-to-face interaction, written information material and informed consent forms play important parts in creating trusting relationships in medical research.</p> <p>Conclusion</p> <p>Medical research ethics do not only amount to specific types of written information material but should also be seen as a number of trust making performances involving researchers as well as research participants.</p
Production and covalent immobilisation of the recombinant bacterial carbonic anhydrase (SspCA) onto magnetic nanoparticles
Carbonic anhydrases (CAs; EC 4.2.1.1) are metalloenzymes with a pivotal potential role in the biomimetic
CO2 capture process (CCP) because these biocatalysts catalyse the simple but physiologically crucial reaction
of carbon dioxide hydration to bicarbonate and protons in all life kingdoms. The CAs are among the
fastest known enzymes, with kcat values of up to 106 s!1 for some members of the superfamily, providing
thus advantages when compared with other CCP methods, as they are specific for CO2. Thermostable CAs
might be used in CCP technology because of their ability to perform catalysis in operatively hard conditions,
typical of the industrial processes. Moreover, the improvement of the enzyme stability and its reuse
are important for lowering the costs. These aspects can be overcome by immobilising the enzyme on a
specific support. We report in this article that the recombinant thermostable SspCA (a-CA) from the
thermophilic bacterium Sulfurihydrogenibium yellowstonense can been heterologously produced by a highdensity
fermentation of Escherichia coli cultures, and covalently immobilised onto the surface of magnetic
Fe3O4 nanoparticles (MNP) via carbodiimide activation reactions. Our results demonstrate that using a
benchtop bioprocess station and strategies for optimising the bacterial growth, it is possible to produce at
low cost a large amount SspCA. Furthermore, the enzyme stability and storage greatly increased through
the immobilisation, as SspCA bound to MNP could be recovered from the reaction mixture by simply using
a magnet or an electromagnetic field, due to the strong ferromagnetic properties of Fe3O4
Placental transfer of the polybrominated diphenyl ethers BDE-47, BDE-99 and BDE-209 in a human placenta perfusion system: an experimental study
<p>Abstract</p> <p>Background</p> <p>Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants in consumer products. PBDEs may affect thyroid hormone homeostasis, which can result in irreversible damage of cognitive performance, motor skills and altered behaviour. Thus, in utero exposure is of very high concern due to critical windows in fetal development.</p> <p>Methods</p> <p>A human ex vivo placenta perfusion system was used to study the kinetics and extent of the placental transfer of BDE-47, BDE-99 and BDE-209 during four-hour perfusions. The PBDEs were added to the maternal circulation and monitored in the maternal and fetal compartments. In addition, the perfused cotyledon, the surrounding placental tissue as well as pre-perfusion placental tissue and umbilical cord plasma were also analysed. The PBDE analysis included Soxhlet extraction, clean-up by adsorption chromatography and GC-MS analysis.</p> <p>Results and Discussion</p> <p>Placental transfer of BDE-47 was faster and more extensive than for BDE-99. The fetal-maternal ratios (FM-ratio) after four hours of perfusion were 0.47 and 0.25 for BDE-47 and BDE-99, respectively, while the indicative permeability coefficient (IPC) measured after 60 minutes of perfusion was 0.26 h<sup>-1 </sup>and 0.10 h<sup>-1</sup>, respectively. The transport of BDE-209 seemed to be limited. These differences between the congeners may be related to the degree of bromination. Significant accumulation was observed for all congeners in the perfused cotyledon as well as in the surrounding placental tissue.</p> <p>Conclusion</p> <p>The transport of BDE-47 and BDE-99 indicates in utero exposure to these congeners. Although the transport of BDE-209 was limited, however, possible metabolic debromination may lead to products which are both more toxic and transportable. Our study demonstrates fetal exposure to PBDEs, which should be included in risk assessment of PBDE exposure of women of child-bearing age.</p
Social Value of Marine and Coastal Protected Areas in England and Wales.
The U.K. government is committed to establishing a coherent network of marine protected
areas by 2012 and the recentMarine and Coastal Access Act, 2009 will designate
marine conservation zones and provide wider access rights to the coast. To fulfill these
goals, this article argues the need for a clearer, shared understanding of the social
value of protected areas in creating new designations and managing existing ones. Although
marine and coastal environments attract many people and are vitally important
in terms of realized and potential social value, the majority of the public in the United
Kingdom lacks understanding and awareness regarding them. Combined with this, the
social value of marine and coastal protected areas (MCPAs) have been largely ignored
relative to conservation and economics, with the latter invariably taking precedence
in environmental policymaking. Social value reflects the complex, individual responses
that people experience in a given place. Many reasons determine why one area is valued
above another, and this research investigates the social value of MCPAs from a
practitioner’s perspective through a series of interviews. Understanding why we “socially”
value MCPAs will ultimately equip managers with an informed understanding
of these spaces, influence management decisions, and, potentially, policymaking. This
article defines social value in the context of MCPAs in England and Wales from a
practitioner perspective, explores key concepts, and suggests possible improvements in
decision-making
Observation of Hadronic W Decays in t-tbar Events with the Collider Detector at Fermilab
We observe hadronic W decays in t-tbar -> W (-> l nu) + >= 4 jet events using
a 109 pb-1 data sample of p-pbar collisions at sqrt{s} = 1.8 TeV collected with
the Collider Detector at Fermilab (CDF). A peak in the dijet invariant mass
distribution is obtained that is consistent with W decay and inconsistent with
the background prediction by 3.3 standard deviations. From this peak we measure
the W mass to be 77.2 +- 4.6 (stat+syst) GeV/c^2. This result demonstrates the
presence of two W bosons in t-tbar candidates in the W (-> l nu) + >= 4 jet
channel.Comment: 20 pages, 4 figures, submitted to PR
Measurement of the Associated Production Cross Section in Collisions at TeV
We present the first measurement of associated direct photon + muon
production in hadronic collisions, from a sample of 1.8 TeV
collisions recorded with the Collider Detector at Fermilab. Quantum
chromodynamics (QCD) predicts that these events are primarily from the Compton
scattering process , with the final state charm quark producing
a muon. Hence this measurement is sensitive to the charm quark content of the
proton. The measured cross section of is compared to a
leading-order QCD parton shower model as well as a next-to-leading-order QCD
calculation.Comment: 12 pages, 4 figures Added more detailed description of muon
background estimat
Inclusive jet cross section in collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb of data
collected by the CDF collaboration at the Fermilab Tevatron collider. The data
are compared with QCD predictions for various sets of parton distribution
functions. The cross section for jets with GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
Measurement of Dijet Angular Distributions at CDF
We have used 106 pb^-1 of data collected in proton-antiproton collisions at
sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular
distributions in events with two jets in the final state. The angular
distributions agree with next to leading order (NLO) predictions of Quantum
Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at
95% confidence level (CL) a model of quark substructure in which only up and
down quarks are composite and the contact interaction scale is Lambda_ud(+) <
1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are
composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6
TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to
Physical Review Letters on September 17, 1996. Postscript file of full paper
available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
Search for charged Higgs decays of the top quark using hadronic tau decays
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 1.8 TeV. When the charged
Higgs is heavy and decays to a tau lepton, which subsequently decays
hadronically, the resulting events have a unique signature: large missing
transverse energy and the low-charged-multiplicity tau. Data collected in the
period 1992-1993 at the Collider Detector at Fermilab, corresponding to
18.70.7~pb, exclude new regions of combined top quark and charged
Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp;
submitted to Phys. Rev.
Effect of Vitamin D Supplementation on Markers of Vascular Function: A Systematic Review and Individual Participant Meta- Analysis
Background-—Low 25-hydroxyvitamin D levels are associated with an increased risk of cardiovascular events, but the effect of
vitamin D supplementation on markers of vascular function associated with major adverse cardiovascular events is unclear.
Methods and Results-—We conducted a systematic review and individual participant meta-analysis to examine the effect of vitamin D
supplementation on flow-mediated dilatation of the brachial artery, pulse wave velocity, augmentation index, central blood pressure,
microvascular function, and reactive hyperemia index. MEDLINE, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, and
http://www.ClinicalTrials.gov were searched until the end of 2016 without language restrictions. Placebo-controlled randomized trials
of at least4 weeks duration were included. Individual participant data were sought from investigators on included trials. Trial-level metaanalysis
was performed using random-effects models; individual participant meta-analyses used a 2-stage analytic strategy, examining
effects in prespecified subgroups. 31trials (2751 participants) were included; 29 trials (2641participants) contributed data to trial-level
meta-analysis, and24trials (2051 participants) contributed to individual-participant analyses. VitaminD3daily dose equivalents ranged
from 900 to 5000 IU; duration was 4 weeks to12 months. Trial-level meta-analysis showed no significant effect of supplementation on
macrovascularmeasures(flow-mediateddilatation,0.37%[95%confidenceinterval, 0.23to0.97]; carotid-femoralpulsewavevelocity,
0.00 m/s [95% confidence interval, 0.36 to 0.37]); similar results were obtained from individual participant data. Microvascular
function showed a modest improvement in trial-level data only. No consistent benefit was observed in subgroup analyses or between
different vitamin D analogues.
Conclusions-—Vitamin D supplementation had no significant effect on most markers of vascular function in this analysis
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