48 research outputs found
Analysis of disease clusters and patient outcomes in people with multiple long term conditions using hypergraphs.
Objectives
Having multiple long term health conditions (MLTCs), also known as multimorbidity, is becoming increasingly common as populations age. Understanding how clusters of diseases are likely to lead to other diseases and the effect of multimorbidity on healthcare resource use (HRU) will be of great importance as this trend continues.
Approach
Graph-based approaches, also called network analysis in the literature, have been used previously to study multimorbidity. The use of hypergraphs, which are generalisations of graphs where edges can connect to any number of nodes, and their application to the problem of understanding multimorbidity will be discussed. Analysis using hypergraphs was carried out using a population-scale cohort of people in the Secure Anonymised Information Linkage (SAIL) Databank to find the diseases and disease sets which are most important based on a measure of prevalence and measures of healthcare resource utilisation in secondary care.
Results
The most important sets of diseases based on the centrality of a hypergraph weighted by a measure of prevalence featured hypertension, and the most important was hypertension and diabetes. The most important sets of diseases based on the centrality of a hypergraph weighted by a measure of unplanned inpatient HRU were arrhythmia, heart failure and hypertension while for a measure of outpatient HRU the most important set of diseases was diabetes and hypertension.
Conclusion
Hypergraphs are very flexible and general mathematical objects and there is still a great deal of development that can be done to make them more useful in epidemiological settings and beyond
Seasonal variation of water uptake of a Quercus suber tree in Central Portugal
Hydraulic redistribution (HR) is the phenomenon
where plant roots transfer water between
soil horizons of different water potential. When dry
soil is a stronger sink for water loss from the plant
than transpiration, water absorbed by roots in wetter
soil horizons is transferred toward, and exuded into
dry soil via flow reversals through the roots. Reverse
flow is a good marker of HR and can serve as a useful
tool to study it over the long-term. Seasonal variation
of water uptake of a Quercus suber tree was studied
from late winter through autumn 2003 at Rio Frio
near Lisbon, Portugal. Sap flow was measured in five
small shallow roots (diameter of 3–4 cm), 1 to 2 m
from the tree trunk and in four azimuths and at
different xylem depths at the trunk base, using the
heat field deformation method (HFD). The pattern of
sap flow differed among lateral roots as soil dried with constant positive flow in three roots and reverse
flow in two other roots during the night when
transpiration ceased. Rain modified the pattern of
flow in these two roots by eliminating reverse flow
and substantially increasing water uptake for transpiration
during the day. The increase in water uptake in
three other roots following rain was not so substantial.
In addition, the flux in individual roots was correlated
to different degrees with the flux at different radial
depths and azimuthal directions in trunk xylem. The
flow in outer trunk xylem seemed to be mostly
consistent with water movement from surface soil
horizons, whereas deep roots seemed to supply water
to the whole cross-section of sapwood. When water
flow substantially decreased in shallow lateral roots
and the outer stem xylem during drought, water flow
in the inner sapwood was maintained, presumably due
to its direct connection to deep roots. Results also
suggest the importance of the sap flow sensor
placement, in relation to sinker roots, as to whether
lateral roots might be found to exhibit reverse flow
during drought. This study is consistent with the
dimorphic rooting habit of Quercus suber trees in
which deep roots access groundwater to supply
superficial roots and the whole tree, when shallow
soil layers were dry
Value of hospital antimicrobial stewardship programs [ASPs]:a systematic review
Abstract Background Hospital antimicrobial stewardship programs (ASPs) aim to promote judicious use of antimicrobials to combat antimicrobial resistance. For ASPs to be developed, adopted, and implemented, an economic value assessment is essential. Few studies demonstrate the cost-effectiveness of ASPs. This systematic review aimed to evaluate the economic and clinical impact of ASPs. Methods An update to the Dik et al. systematic review (2000–2014) was conducted on EMBASE and Medline using PRISMA guidelines. The updated search was limited to primary research studies in English (30 September 2014–31 December 2017) that evaluated patient and/or economic outcomes after implementation of hospital ASPs including length of stay (LOS), antimicrobial use, and total (including operational and implementation) costs. Results One hundred forty-six studies meeting inclusion criteria were included. The majority of these studies were conducted within the last 5 years in North America (49%), Europe (25%), and Asia (14%), with few studies conducted in Africa (3%), South America (3%), and Australia (3%). Most studies were conducted in hospitals with 500–1000 beds and evaluated LOS and change in antibiotic expenditure, the majority of which showed a decrease in LOS (85%) and antibiotic expenditure (92%). The mean cost-savings varied by hospital size and region after implementation of ASPs. Average cost savings in US studies were 2.50 to $2640), with similar trends exhibited in European studies. The key driver of cost savings was from reduction in LOS. Savings were higher among hospitals with comprehensive ASPs which included therapy review and antibiotic restrictions. Conclusions Our data indicates that hospital ASPs have significant value with beneficial clinical and economic impacts. More robust published data is required in terms of implementation, LOS, and overall costs so that decision-makers can make a stronger case for investing in ASPs, considering competing priorities. Such data on ASPs in lower- and middle-income countries is limited and requires urgent attention
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
Reflections of Near-Death Experiences and Deathbed Visions: A Study of Nursing Faculty's Perceptions
ABSTRACT: Nursing faculty across the United States were surveyed about their knowledge, attitudes, and perspectives of near-death experiences (NDEs) and deathbed visions (DBVs) through web-based administration of the Near-Death Phenomena Knowledge and Attitudes Questionnair