12,906 research outputs found
Shock absorbing support and restraint means Patent
Shock absorbing couch for body support under high acceleration or deceleration force
mtDNA diversity in human populations highlights the merit of haplotype matching in gene therapies
STUDY QUESTION Does mitochondrial DNA (mtDNA) diversity in modern human populations potentially pose a challenge, via mtDNA segregation, to mitochondrial replacement therapies?
SUMMARY ANSWER The magnitude of mtDNA diversity in modern human populations is as high as in mammalian model systems where strong mtDNA segregation is observed; consideration of haplotype pairs and/or haplotype matching can help avoid these potentially deleterious effects.
WHAT IS KNOWN ALREADY In mammalian models, substantial proliferative differences are observed between different mtDNA haplotypes in cellular admixtures, with larger proliferative differences arising from more diverse haplotype pairings. If maternal mtDNA is âcarried overâ in human gene therapies, these proliferative differences could lead to its amplification in the resulting offspring, potentially leading to manifestation of the disease that the therapy was designed to avoidâbut existing studies have not investigated whether mtDNA diversity in modern human populations is sufficient to permit significant amplification.
STUDY DESIGN, SIZE, DURATION This theoretical study used over 7500 human mtDNA sequences from The National Center for Biotechnology Information (NCBI), a range of international and British mtDNA surveys, and 2011 census data.
PARTICIPANTS/MATERIALS, SETTING, METHODS A stochastic simulation approach was used to model random haplotype pairings from within different regions. In total, 1000 simulated pairings were analysed using the basic local alignment search tool (BLAST) for each region. Previous data from mouse models were used to estimate proliferative differences.
MAIN RESULTS AND THE ROLE OF CHANCE Even within the same haplogroup, differences of around 20â80 single-nucleotide polymorphisms (SNPs) are common between mtDNAs admixed in random pairings. These values are sufficient to lead to substantial segregation in mouse models over an organismal lifetime, even given low starting heteroplasmy, inducing increases from 5% to 35% over 1 year. Substantial population mixing in modern UK cities increases the expected genetic differences. Hence, the likely genetic differences between humans randomly sampled from a population may well allow substantial amplification of a disease-carrying mtDNA haplotype over the timescale of a human lifetime. We report ranges and mean differences for all statistics to quantify uncertainty in our results.
LIMITATIONS/REASONS FOR CAUTION The mapping from mouse and other mammalian models to the human system is challenging, as timescales and mechanisms may differ. Reporting biases in NCBI mtDNA data, if present, may affect the statistics we compute. We discuss the robustness of our findings in the light of these concerns.
WIDER IMPLICATIONS OF THE FINDINGS Matching the mtDNA haplotypes of the mother and third-party donor in mitochondrial replacement therapies is supported as a means of ameliorating the potentially deleterious results of human mtDNA diversity. We present a chart of expected SNP differences between mtDNA haplogroups, allowing the selection of optimal partners for therapies
Phasing of muscle gene expression with fasting-induced recovery growth in Atlantic salmon
Background: Many fish species experience long periods of fasting in nature often associated with seasonal reductions in water temperature and prey availability or spawning migrations. During periods of nutrient restriction, changes in metabolism occur to provide cellular energy via catabolic processes. Muscle is particularly affected by prolonged fasting as myofibrillar proteins act as a major energy source. To investigate the mechanisms of metabolic reorganisation with fasting and refeeding in a saltwater stage of Atlantic salmon (Salmo salar L.) we analysed the expression of genes involved in myogenesis, growth signalling, lipid biosynthesis and myofibrillar protein degradation and synthesis pathways using qPCR. Results: Hierarchical clustering of gene expression data revealed three clusters. The first cluster comprised genes involved in lipid metabolism and triacylglycerol synthesis (ALDOB, DGAT1 and LPL) which had peak expression 3-14d after refeeding. The second cluster comprised ADIPOQ, MLC2, IGF-I and TALDO1, with peak expression 14-32d after refeeding. Cluster III contained genes strongly down regulated as an initial response to feeding and included the ubiquitin ligases MuRF1 and MAFbx, myogenic regulatory factors and some metabolic genes. Conclusion: Early responses to refeeding in fasted salmon included the synthesis of triacylglycerols and activation of the adipogenic differentiation program. Inhibition of MuRF1 and MAFbx respectively may result in decreased degradation and concomitant increased production of myofibrillar proteins. Both of these processes preceded any increase in expression of myogenic regulatory factors and IGF-I. These responses could be a necessary strategy for an animal adapted to long periods of food deprivation whereby energy reserves are replenished prior to the resumption of myogenesis.Publisher PDFPeer reviewe
In-situ temperature calibration procedure for temperature and strain fibre Bragg grating sensors for monitoring pre-stressing strands
In this work, we demonstrate active and passive methods for in-situ temperature calibration of fibre Bragg grating strain and temperature sensors. The method is suitable for characterizing sensors which are already attached to the steel reinforcements of civil structures. The proposed method, which involves the use of active induction heating or passive room temperature fluctuations, can be implemented using portable equipment, is time efficient, and can be used to calibrate attached sensors on-site, rather than in lab conditions. Preliminary results of the induction heating calibration show good agreement with pre-calibrated temperature sensors. In-situ calibration of fibre strain sensors, attached to a prestressing strand is also successfully carried out
Withdrawal of anticancer therapy in advanced disease: a systematic literature review
Abstract
Background
Current guidelines set out when to start anticancer treatments, but not when to stop as the end of life approaches. Conventional cytotoxic agents are administered intravenously and have major life-threatening toxicities. Newer drugs include molecular targeted agents (MTAs), in particular, small molecule kinase-inhibitors (KIs), which are administered orally. These have fewer life-threatening toxicities, and are increasingly used to palliate advanced cancer, generally offering additional months of survival benefit. MTAs are substantially more expensive, between ÂŁ2-8Â K per month, and perceived as easier to start than stop.
Methods
A systematic review of decision-making concerning the withdrawal of anticancer drugs towards the end of life within clinical practice, with a particular focus on MTAs. Nine electronic databases searched. PRISMA guidelines followed.
Results
Forty-two studies included. How are decisions made? Decision-making was shared and ongoing, including stopping, starting and trying different treatments. Oncologists often experienced âprofessional role dissonanceâ between their self-perception as âtreatersâ, and talking about end of life care. Why are decisions made? Clinical factors: disease progression, worsening functional status, treatment side-effects. Non-clinical factors: physiciansâ personal experience, values, emotions. Some patients continued treatment to maintain âhopeâ, often reflecting limited understanding of palliative goals. When are decisions made? Limited evidence reveals patientsâ decisions based upon quality of life benefits. Clinicians found timing withdrawal particularly challenging. Who makes the decisions? Decisions were based within physician-patient interaction.
Conclusions
Oncologists report that decisions around stopping chemotherapy treatment are challenging, with limited evidence-based guidance outside of clinical trial protocols. The increasing availability of oral MTAs is transforming the management of incurable cancer; blurring boundaries between active treatment and palliative care. No studies specifically addressing decision-making around stopping MTAs in clinical practice were identified. There is a need to develop an evidence base to support physicians and patients with decision-making around the withdrawal of these high cost treatments
Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)
Neutron and x-ray powder diffraction have been used to investigate the
crystal structures of a sample of the newly-discovered superconducting sodium
cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its
anhydrous parent compound Na0.61(1)CoO2. The deuterate superconducting compound
is formed by coordinating four D2O molecules (two above and two below) to each
Na ion in a way that gives Na-O distances nearly equal to those in the parent
compound. One deuteron of the D2O molecule is hydrogen bonded to an oxygen atom
in the CoO2 plane and the oxygen atom and the second deuteron of each D2O
molecule lie approximately in a plane between the Na layer and the CoO2 layers.
This coordination of Na by four D2O molecules leads to ordering of the Na ions
and D2O molecules. The sample studied here, which has Tc=4.5 K, has a refined
composition of Na0.31(3)CoO2o1.25(2)D2O, in agreement with the expected 1:4
ratio of Na to D2O. These results show that the optimal superconducting
composition should be viewed as a specific hydrated compound, not a solid
solution of Na and D2O (H2O) in NaxCoO2oyD2O. Studies of physical properties
vs. Na or D2O composition should be viewed with caution until it is verified
that the compound remains in the same phase over the composition range of the
study.Comment: 22 pages, 8 figure
Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia
PanâArctic riverine dissolved organic carbon (DOC) fluxes represent a major transfer of carbon from landâtoâocean, and past scaling estimates have been predominantly derived from the six major Arctic rivers. However, smaller watersheds are constrained to northern highâlatitude regions and, particularly with respect to the Eurasian Arctic, have received little attention. In this study, we evaluated the concentration of DOC and composition of dissolved organic matter (DOM) via optical parameters, biomarkers (lignin phenols), and ultrahigh resolution mass spectrometry in the Northern Dvina River (a midsized highâlatitude constrained river). Elevated DOC, lignin concentrations, and aromatic DOM indicators were observed throughout the year in comparison to the major Arctic rivers with seasonality exhibiting a clear spring freshet and also some years a secondary pulse in the autumn concurrent with the onset of freezing. Chromophoric DOM absorbance at a350 was strongly correlated to DOC and lignin across the hydrograph; however, the relationships did not fit previous models derived from the six major Arctic rivers. Updated DOC and lignin fluxes were derived for the panâArctic watershed by scaling from the Northern Dvina resulting in increased DOC and lignin fluxes (50 Tg yrâ1 and 216 Gg yrâ1, respectively) compared to past estimates. This leads to a reduction in the residence time for terrestrial carbon in the Arctic Ocean (0.5 to 1.8 years). These findings suggest that constrained northern highâlatitude rivers are underrepresented in models of fluxes based from the six largest Arctic rivers with important ramifications for the export and fate of terrestrial carbon in the Arctic Ocean
Unraveling the Nature of Charge Excitations in LaCuO with Momentum-Resolved Cu -edge Resonant Inelastic X-ray Scattering
Results of model calculations using exact diagonalization reveal the orbital
character of states associated with different Raman loss peaks in Cu -edge
resonant inelastic X-ray scattering (RIXS) from LaCuO. The model
includes electronic orbitals necessary to highlight non-local Zhang-Rice
singlet, charge transfer and - excitations, as well as states with apical
oxygen 2 character. The dispersion of these excitations is discussed with
prospects for resonant final state wave-function mapping. A good agreement with
experiments emphasizes the substantial multi-orbital character of RIXS profiles
in the energy transfer range 1-6 eV.Comment: Original: 4.5 pages. Replaced: 4 pages and 4 figures with updated
content and reference
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