746 research outputs found
Effect of individual-level and socioeconomic factors on long-term survival after cataract surgery over a 30-year period
Purpose:
To evaluate survival and the risk for mortality after cataract surgery in relation to individual-level and socioeconomic factors in Scotland over 3 decades.
Setting:
Linked healthcare data, United Kingdom.
Design:
Representative population-based study.
Methods:
A 5% random sample of Scottish decedents linked to hospital records (1981 to 2012) was assessed. Survival time, survival probability, and determinants of mortality were evaluated after the first and second recorded hospital episodes for cataract surgery. Cox proportional-hazards regression models were used to assess the effect of individual-level and socioeconomic factors including age, geographic location, socioeconomic status, and comorbidity on mortality.
Results:
The study evaluated linked administrative healthcare data from 9228 deceased patients who had cataract surgery. The mean survival time was 2383 days ± 1853 (SD). The survival probability decreased from 98% 90 days after surgery to 22% at 10 years, 2% at 20 years, and 0% after 30 years. The mean age was 77 ± 9 years. Age (hazard ratio [HR] 3.66; 95% confidence interval [CI], 2.97-3.80; P < .001) and severe comorbidity (HR 1.68; 95% CI, 1.47-1.91; P < .001) were associated with an increased risk for mortality; women had a 20% lower risk than men (HR 0.80; 95% CI, 0.76-0.83; P < .001). Socioeconomic status and rural geographic locations were not linked to mortality.
Conclusions:
Long-term survival after cataract surgery was determined by individual-level characteristics reflecting the mortality patterns of aging populations. The mortality risk was independent of socioeconomic and geographic factors per se
Flavoured soft leptogenesis and natural values of the B term
We revisit flavour effects in soft leptogenesis relaxing the assumption of
universality for the soft supersymmetry breaking terms. We find that with
respect to the case in which the heavy sneutrinos decay with equal rates and
equal CP asymmetries for all lepton flavours, hierarchical flavour
configurations can enhance the efficiency by more than two orders of magnitude.
This translates in more than three order of magnitude with respect to the
one-flavour approximation. We verify that lepton flavour equilibration effects
related to off-diagonal soft slepton masses are ineffective for damping these
large enhancements. We show that soft leptogenesis can be successful for
unusual values of the relevant parameters, allowing for and for values of the washout parameter up to .Comment: 23 pages, 5 figures postscript, Minor changes to match the published
version in JHE
Non-resonant leptogenesis in seesaw models with an almost conserved B-L
We review the motivations and some results on leptogenesis in seesaw models
with an almost conserved lepton number. The paper is based on a talk given at
the 5th International Symposium on Symmetries in Subatomic Physics, SSP2012.Comment: 8 pages, 1 figure. Published in the proceedings of the 5th
International Symposium on Symmetries in Subatomic Physics, SSP201
Is Pesticide Use Related to Parkinson Disease? Some Clues to Heterogeneity in Study Results
Background: Previous systematic reviews have indicated that pesticide exposure is possibly associated with Parkinson disease (PD). However, considerable heterogeneity has been observed in study results
Reporting of ethical considerations in clinical trials in Chinese nursing journals
Background: It is acknowledged that publishers now require all primary research papers to demonstrate
that they have obtained ethical approval for their research.
Objectives: To assess the rate of reporting of ethical approval in clinical trials in core nursing journals in
mainland China.
Research design:
A retrospective observational study.
Participants:
All clinical trials published in all of the 12 core nursing periodicals from 2016 edition China
Science and Technology Journal Citation Report (core version) between 2013 and 2016 were retrieved by hand
to explicate rate of reporting ethical approval and informed consent.
Ethical considerations:
The study did not require approval from the research ethics committee as it did
not involve human subjects or records.
Results:
In total, 40,278 papers were published in 12 nursing periodicals between 2013 and 2016. Out of
these, 9488 (23.6%) focused on clinical trials. Informed consent obtained from patients or the legally
authorized representative was reported in 51.8% of clinical trials. Notably, only 27.4% of clinical trials
reported that they had obtained written consent. Furthermore, 25.9% of clinical trials described ethical
approval; however, the rate of reporting informed consent and ethical approval in these 12 nursing journals
in China during 4 years from 2013 to 2016 improved markedly, with 38.1%, 44.0%, 59.0% and 66.6%,
respectively (p<0.001), and 17.6%, 21.9%, 28.6% and 35.8%, respectively (p<0.001). In addition, both
reporting informed consent and reporting written informed consent had a positive significant correlation
with the reporting ethical approval (p<0.05 or p<0.01).
Conclusion:
Chinese scientific nursing journals have improved the rate of reporting informed consent and
ethical approval in clinical trials during the last 4 years. However, it should be noted that nearly half of clinical trials still did not report either ethical approval or whether informed consent was obtained. Efforts from
editors, researchers, sponsors and authors are needed to ensure the transparency of ethical scrutiny and
adherence to ethical guidelines in publishing clinical trials in Chinese nursing journals
Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims
Inspired by the decaying dark matter (DM) which can explain cosmic ray
anomalies naturally, we consider the supersymmetric Standard Model with three
right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector
with two fields \phi_{1,2} and a discrete symmetry. The DM sector only
interacts with the RHNs via a very heavy field exchange and then we can explain
the cosmic ray anomalies. With the second right-handed neutrino N_2 dominant
seesaw mechanism at the low scale around 10^4 GeV, we show that \phi_{1,2} can
obtain the vacuum expectation values around the TeV scale, and then the
lightest state from \phi_{1,2} is the decay DM with lifetime around \sim
10^{26}s. In particular, the DM very long lifetime is related to the tiny
neutrino masses, and the dominant DM decay channels to \mu and \tau are related
to the approximate \mu-\tau symmetry. Furthermore, the correct DM relic density
can be obtained via the freeze-in mechanism, the small-scale problem for power
spectrum can be solved due to the decays of the R-parity odd meta-stable states
in the DM sector, and the baryon asymmetry can be generated via the soft
leptogensis.Comment: 24 pages,3 figure
MultiMetEval: comparative and multi-objective analysis of genome-scale metabolic models
Comparative metabolic modelling is emerging as a novel field, supported by the development of reliable and standardized approaches for constructing genome-scale metabolic models in high throughput. New software solutions are needed to allow efficient comparative analysis of multiple models in the context of multiple cellular objectives. Here, we present the user-friendly software framework Multi-Metabolic Evaluator (MultiMetEval), built upon SurreyFBA, which allows the user to compose collections of metabolic models that together can be subjected to flux balance analysis. Additionally, MultiMetEval implements functionalities for multi-objective analysis by calculating the Pareto front between two cellular objectives. Using a previously generated dataset of 38 actinobacterial genome-scale metabolic models, we show how these approaches can lead to exciting novel insights. Firstly, after incorporating several pathways for the biosynthesis of natural products into each of these models, comparative flux balance analysis predicted that species like Streptomyces that harbour the highest diversity of secondary metabolite biosynthetic gene clusters in their genomes do not necessarily have the metabolic network topology most suitable for compound overproduction. Secondly, multi-objective analysis of biomass production and natural product biosynthesis in these actinobacteria shows that the well-studied occurrence of discrete metabolic switches during the change of cellular objectives is inherent to their metabolic network architecture. Comparative and multi-objective modelling can lead to insights that could not be obtained by normal flux balance analyses. MultiMetEval provides a powerful platform that makes these analyses straightforward for biologists. Sources and binaries of MultiMetEval are freely available from https://github.com/PiotrZakrzewski/MetEv​al/downloads
Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
Developing a 3D intestinal epithelium model for livestock species
© 2018, The Author(s). The in vitro 3D culture of intestinal epithelium is a valuable resource in the study of its function. Organoid culture exploits stem cells’ ability to regenerate and produce differentiated epithelium. Intestinal organoid models from rodent or human tissue are widely available whereas large animal models are not. Livestock enteric and zoonotic diseases elicit significant morbidity and mortality in animal and human populations. Therefore, livestock species-specific models may offer novel insights into host-pathogen interactions and disease responses. Bovine and porcine jejunum were obtained from an abattoir and their intestinal crypts isolated, suspended in Matrigel, cultured, cryopreserved and resuscitated. ‘Rounding’ of crypts occurred followed by budding and then enlargement of the organoids. Epithelial cells were characterised using immunofluorescent staining and confocal microscopy. Organoids were successfully infected with Toxoplasma gondii or Salmonella typhimurium. This 3D organoid model offers a long-term, renewable resource for investigating species-specific intestinal infections with a variety of pathogens
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