4,200 research outputs found
A Rapid Chromatographic Method For Recovery Of 15No2- And No3- Produced By Nitrification In Aqueous Samples
The sensitivity and comparative simplicity of N-15 stable isotopic tracer techniques has been used to quantify rates of nitrification in aquatic systems. However, the most commonly used method for recovery of inorganic oxidized nitrogen compounds from aqueous samples, which is based on liquid-liquid partitioning, is time consuming and contamination prone. We describe a solid-phase rapid chromatographic method for recovery of (NO2-)-N-15 and NO3- produced by nitrification in aqueous samples. Compared to liquid-liquid partitioning, the advantages are significantly reduced processing time and reduced potential for contamination. Typical results are presented for the tidal, freshwater reaches of the James River estuary
Discontinuity in the subjective experience of self among people with mild-to-moderate dementia is associated with poorer psychological health: findings from the IDEAL cohort
This is the final version. Available from the publisher via the DOI in this record.IDEAL data were deposited with the UK data archive in April 2020 and will be available for access from April 2023. Details of how the data can be accessed after that date can be found here: http://reshare.ukdataservice.ac.uk/854293/.BACKGROUND: The onset and progression of dementia can result in changes in the subjective experience of self, impacting on psychological health. OBJECTIVE: We aimed to explore the extent to which people with mild-to-moderate dementia experience discontinuity in the subjective experience of self, and the factors associated with this experience for people with dementia and their family caregivers. METHODS: We used data from the baseline assessment of the IDEAL cohort. Discontinuity in the subjective experience of self was assessed by asking participants about their agreement with the statement 'I feel I am the same person that I have always been'. Participants were divided into those who did and did not experience discontinuity, and the two groups were compared in terms of demographic and disease-related characteristics, psychological well-being, measures of 'living well', and caregiver stress. RESULTS: Responses to the continuity question were available for 1,465 participants with dementia, of whom 312 (21%) reported experiencing discontinuity. The discontinuity group experienced significantly poorer psychological well-being and had significantly lower scores on measures of 'living well'. There was no clear association with demographic or disease-related characteristics, but some indication of increased caregiver stress. CONCLUSION: A significant proportion of people with mild-to-moderate dementia describe experiencing discontinuity in the subjective sense of self, and this is associated with poorer psychological health and reduced ability to 'live well' with the condition. Sensitively asking individuals with dementia about the subjective experience of self may offer a simple means of identifying individuals who are at increased risk of poor well-being.Economic and Social Research Council (ESRC)Alzheimer's Societ
Protocol for The Toxin Study: Understanding clinical and patient reported response of children and young people with cerebral palsy to intramuscular lower limb Botulinum neurotoxin-A injections, exploring all domains of the ICF. A pragmatic longitudinal observational study using a prospective one-group repeated measures design
INTRODUCTION: Botulinum neurotoxin-A (BoNT-A) is an accepted treatment modality for the management of hypertonia in children and young people with cerebral palsy (CYPwCP). Nevertheless, there are concerns about the long-term effects of BoNT-A, with a lack of consensus regarding the most meaningful outcome measures to guide its use. Most evidence to date is based on short-term outcomes, related to changes at impairment level (restrictions of body functions and structures), rather than changes in adaptive skills (enabling both activity and participation). The proposed study aims to evaluate clinical and patient reported outcomes in ambulant CYPwCP receiving lower limb BoNT-A injections over a 12-month period within all domains of the WHO's International Classification of Functioning, Disability and Health and health-related quality of life (HRQoL). METHODS AND ANALYSIS: This pragmatic prospective longitudinal observational study will use a one-group repeated measures design. Sixty CYPwCP, classified as Gross Motor Function Classification System (GMFCS) levels I-III, aged between 4 and 18 years, will be recruited from an established movement disorder service in London, UK. Standardised clinical and patient reported outcome measures within all ICF domains; body structures and function, activity (including quality of movement), goal attainment, participation and HRQoL, will be collected preinjection and at 6 weeks, 6 months and up to 12 months postinjection. A representative subgroup of children and carers will participate in a qualitative component of the study, exploring how their experience of BoNT-A treatment relates to clinical outcome measures. ETHICS AND DISSEMINATION: Central London Research Ethics Committee has granted ethics approval (#IRAS 211617 #REC 17/LO/0579). Findings will be disseminated in peer-reviewed publications, conferences and via networks to participants and relevant stakeholders using a variety of accessible formats including social media
Protocol for The Toxin Study: Understanding clinical and patient reported response of children and young people with cerebral palsy to intramuscular lower limb Botulinum neurotoxin-A injections, exploring all domains of the ICF. A pragmatic longitudinal observational study using a prospective one-group repeated measures design
This is the final version. Available from BMJ Publishing Group via the DOI in this record. Introduction: Botulinum neurotoxin-A (BoNT-A) is an accepted treatment modality for the management of hypertonia in children and young people with cerebral palsy (CYPwCP). Nevertheless, there are concerns about the long-term effects of BoNT-A, with a lack of consensus regarding the most meaningful outcome measures to guide its use. Most evidence to date is based on short-term outcomes, related to changes at impairment level (restrictions of body functions and structures), rather than changes in adaptive skills (enabling both activity and participation). The proposed study aims to evaluate clinical and patient reported outcomes in ambulant CYPwCP receiving lower limb BoNT-A injections over a 12-month period within all domains of the WHO’s International Classification of Functioning, Disability and Health and health-related quality of life (HRQoL). Methods and analysis: This pragmatic prospective longitudinal observational study will use a one-group repeated measures design. Sixty CYPwCP, classified as Gross Motor Function Classification System (GMFCS) levels I–III, aged between 4 and 18 years, will be recruited from an established movement disorder service in London, UK. Standardised clinical and patient reported outcome measures within all ICF domains; body structures and function, activity (including quality of movement), goal attainment, participation and HRQoL, will be collected preinjection and at 6 weeks, 6 months and up to 12 months postinjection. A representative subgroup of children and carers will participate in a qualitative component of the study, exploring how their experience of BoNT-A treatment relates to clinical outcome measures. Ethics and dissemination: Central London Research Ethics Committee has granted ethics approval (#IRAS 211617 #REC 17/LO/0579). Findings will be disseminated in peer-reviewed publications, conferences and via networks to participants and relevant stakeholders using a variety of accessible formats including social media.National Institute for Health Research (NIHR
Low-temperature muon spin rotation studies of the monopole charges and currents in Y doped Ho2Ti2O7
In the ground state of Ho2Ti2O7 spin ice, the disorder of the magnetic moments follows the same rules as the proton disorder in water ice. Excitations take the form of magnetic monopoles that interact via a magnetic Coulomb interaction. Muon spin rotation has been used to probe the low-temperature magnetic behaviour in single crystal Ho2−xYxTi2O7 (x = 0, 0.1, 1, 1.6 and 2). At very low temperatures, a linear field dependence for the relaxation rate of the muon precession λ(B), that in some previous experiments on Dy2Ti2O7 spin ice has been associated with monopole currents, is observed in samples with x = 0, and 0.1. A signal from the magnetic fields penetrating into the silver sample plate due to the magnetization of the crystals is observed for all the samples containing Ho allowing us to study the unusual magnetic dynamics of Y doped spin ice
Vortex nucleation as a case study of symmetry breaking in quantum systems
Mean-field methods are a very powerful tool for investigating weakly
interacting many-body systems in many branches of physics. In particular, they
describe with excellent accuracy trapped Bose-Einstein condensates. A generic,
but difficult question concerns the relation between the symmetry properties of
the true many-body state and its mean-field approximation. Here, we address
this question by considering, theoretically, vortex nucleation in a rotating
Bose-Einstein condensate. A slow sweep of the rotation frequency changes the
state of the system from being at rest to the one containing one vortex. Within
the mean-field framework, the jump in symmetry occurs through a turbulent phase
around a certain critical frequency. The exact many-body ground state at the
critical frequency exhibits strong correlations and entanglement. We believe
that this constitutes a paradigm example of symmetry breaking in - or change of
the order parameter of - quantum many-body systems in the course of adiabatic
evolution.Comment: Minor change
Exploring haemodynamics of haemodialysis using extrema points analysis model
Background: Haemodialysis is a form of renal replacement therapy used to treat
patients with end stage renal failure. It is becoming more appreciated that
haemodialysis patients exhibit higher rates of multiple end organ damage
compared to the general population. There is also a strong emerging evidence that
haemodialysis itself causes circulatory stress. We aimed at examining
haemodynamic patterns during haemodialysis using a new model and test that
model against a normal control.
Methods: We hypothesised that blood pressures generated by each heart beat
constantly vary between local peaks and troughs (local extrema), the frequency and
amplitude of which is regulated to maintain optimal organ perfusion. We also
hypothesised that such model could reveal multiple haemodynamic aberrations
during HD. Using a non-invasive cardiac output monitoring device (Finometer®) we
compared various haemodynamic parameters using the above model between a
haemodialysis patient during a dialysis session and an exercised normal control after
comparison at rest.
Results: Measurements yielded 29,751 data points for each haemodynamic
parameter. Extrema points frequency of mean arterial blood pressure was higher in
the HD subject compared to the normal control (0.761Hz IQR 0.5-0.818 vs 0.468Hz
IQR 0.223-0.872, P < 0.0001). Similarly, extrema points frequency of systolic blood
pressure was significantly higher in haemodialysis compared to normal. In contrary,
the frequency of extrema points for TPR was higher in the normal control compared
to HD (0.947 IQR 0.520-1.512 vs 0.845 IQR 0.730-1.569, P < 0.0001) with significantly
higher amplitudes.
Conclusion: Haemodialysis patients potentially exhibit an aberrant haemodynamic
behaviour characterised by higher extrema frequencies of mean arterial blood
pressure and lower extrema frequencies of total peripheral resistance. This, in
theory, could lead to higher variation in organ perfusion and may be detrimental to vulnerable vascular beds
Application of the speed-duration relationship to normalize the intensity of high-intensity interval training
The tolerable duration of continuous high-intensity exercise is determined by the hyperbolic Speed-tolerable duration (S-tLIM) relationship. However, application of the S-tLIM relationship to normalize the intensity of High-Intensity Interval Training (HIIT) has yet to be considered, with this the aim of present study. Subjects completed a ramp-incremental test, and series of 4 constant-speed tests to determine the S-tLIM relationship. A sub-group of subjects (n = 8) then repeated 4 min bouts of exercise at the speeds predicted to induce intolerance at 4 min (WR4), 6 min (WR6) and 8 min (WR8), interspersed with bouts of 4 min recovery, to the point of exercise intolerance (fixed WR HIIT) on different days, with the aim of establishing the work rate that could be sustained for 960 s (i.e. 4×4 min). A sub-group of subjects (n = 6) also completed 4 bouts of exercise interspersed with 4 min recovery, with each bout continued to the point of exercise intolerance (maximal HIIT) to determine the appropriate protocol for maximizing the amount of high-intensity work that can be completed during 4×4 min HIIT. For fixed WR HIIT tLIM of HIIT sessions was 399±81 s for WR4, 892±181 s for WR6 and 1517±346 s for WR8, with total exercise durations all significantly different from each other (P<0.050). For maximal HIIT, there was no difference in tLIM of each of the 4 bouts (Bout 1: 229±27 s; Bout 2: 262±37 s; Bout 3: 235±49 s; Bout 4: 235±53 s; P>0.050). However, there was significantly less high-intensity work completed during bouts 2 (153.5±40. 9 m), 3 (136.9±38.9 m), and 4 (136.7±39.3 m), compared with bout 1 (264.9±58.7 m; P>0.050). These data establish that WR6 provides the appropriate work rate to normalize the intensity of HIIT between subjects. Maximal HIIT provides a protocol which allows the relative contribution of the work rate profile to physiological adaptations to be considered during alternative intensity-matched HIIT protocols
Gene variants influencing measures of inflammation or predisposing to autoimmune and inflammatory diseases are not associated with the risk of type 2 diabetes.
AIMS/HYPOTHESIS: There are strong associations between measures of inflammation and type 2 diabetes, but the causal directions of these associations are not known. We tested the hypothesis that common gene variants known to alter circulating levels of inflammatory proteins, or known to alter autoimmune-related disease risk, influence type 2 diabetes risk. METHODS: We selected 46 variants: (1) eight variants known to alter circulating levels of inflammatory proteins, including those in the IL18, IL1RN, IL6R, MIF, PAI1 (also known as SERPINE1) and CRP genes; and (2) 38 variants known to predispose to autoimmune diseases, including type 1 diabetes. We tested the associations of these variants with type 2 diabetes using a meta-analysis of 4,107 cases and 5,187 controls from the Wellcome Trust Case Control Consortium, the Diabetes Genetics Initiative, and the Finland-United States Investigation of NIDDM studies. We followed up associated variants (p < 0.01) in a further set of 3,125 cases and 3,596 controls from the UK. RESULTS: We found no evidence that inflammatory or autoimmune disease variants are associated with type 2 diabetes (at p <or= 0.01). The OR observed between the variant altering IL-18 levels, rs2250417, and type 2 diabetes (OR 1.00 [95% CI 0.99-1.03]), is much lower than that expected given (1) the effect of the variant on IL-18 levels (0.28 SDs per allele); and (2) estimates, based on other studies, of the correlation between IL-18 levels and type 2 diabetes risk (approximate OR 1.15 [95% CI 1.09-1.21] per 0.28 SD increase in IL-18 levels). CONCLUSIONS/INTERPRETATION: Our study provided no evidence that variants known to alter measures of inflammation, autoimmune or inflammatory disease risk, including type 1 diabetes, alter type 2 diabetes risk
Obesity-induced insulin resistance in human skeletal muscle is characterised by defective activation of p42/p44 MAP kinase
Insulin resistance (IR), an impaired cellular, tissue and whole body response to insulin, is a major pathophysiological defect of type 2 diabetes mellitus. Although IR is closely associated with obesity, the identity of the molecular defect(s) underlying obesity-induced IR in skeletal muscle remains controversial; reduced post-receptor signalling of the insulin receptor substrate 1 (IRS1) adaptor protein and downstream effectors such as protein kinase B (PKB) have previously been implicated. We examined expression and/or activation of a number of components of the insulin-signalling cascade in skeletal muscle of 22 healthy young men (with body mass index (BMI) range, 20–37 kg/m2). Whole body insulin sensitivity (M value) and body composition was determined by the hyperinsulinaemic (40 mU. min−1.m−2.), euglycaemic clamp and by dual energy X-ray absorptiometry (DEXA) respectively. Skeletal muscle (vastus lateralis) biopsies were taken before and after one hour of hyperinsulinaemia and the muscle insulin signalling proteins examined by western blot and immunoprecipitation assay. There was a strong inverse relationship between M-value and BMI. The most striking abnormality was significantly reduced insulin-induced activation of p42/44 MAP kinase, measured by specific assay, in the volunteers with poor insulin sensitivity. However, there was no relationship between individuals' BMI or M-value and protein expression/phosphorylation of IRS1, PKB, or p42/44 MAP kinase protein, under basal or hyperinsulinaemic conditions. In the few individuals with poor insulin sensitivity but preserved p42/44 MAP kinase activation, other signalling defects were evident. These findings implicate defective p42/44 MAP kinase signalling as a potential contributor to obesity-related IR in a non-diabetic population, although clearly multiple signalling defects underlie obesity associated IR
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