Animal models have been used extensively in diabetes research. Early studies used pancreatectomised dogs to confirm the central role of the pancreas in glucose homeostasis, culminating in the ...discovery and purification of insulin. Today, animal experimentation is contentious and subject to legal and ethical restrictions that vary throughout the world. Most experiments are carried out on rodents, although some studies are still performed on larger animals. Several toxins, including streptozotocin and alloxan, induce hyperglycaemia in rats and mice. Selective inbreeding has produced several strains of animal that are considered reasonable models of Type 1 diabetes, Type 2 diabetes and related phenotypes such as obesity and insulin resistance. Apart from their use in studying the pathogenesis of the disease and its complications, all new treatments for diabetes, including islet cell transplantation and preventative strategies, are initially investigated in animals. In recent years, molecular biological techniques have produced a large number of new animal models for the study of diabetes, including knock‐in, generalized knock‐out and tissue‐specific knockout mice.
The role of serrated polyps (SPs) as colorectal cancer precursor is increasingly recognised. However, the true prevalence SPs is largely unknown. We aimed to evaluate the detection rate of SPs ...subtypes as well as serrated polyposis syndrome (SPS) among European screening cohorts.
Prospectively collected screening cohorts of ≥1000 individuals were eligible for inclusion. Colonoscopies performed before 2009 and/or in individuals aged below 50 were excluded. Rate of SPs was assessed, categorised for histology, location and size. Age-sex-standardised number needed to screen (NNS) to detect SPs were calculated. Rate of SPS was assessed in cohorts with known colonoscopy follow-up data. Clinically relevant SPs (regarded as a separate entity) were defined as SPs ≥10 mm and/or SPs >5 mm in the proximal colon.
Three faecal occult blood test (FOBT) screening cohorts and two primary colonoscopy screening cohorts (range 1.426-205.949 individuals) were included. Rate of SPs ranged between 15.1% and 27.2% (median 19.5%), of sessile serrated polyps between 2.2% and 4.8% (median 3.3%) and of clinically relevant SPs between 2.1% and 7.8% (median 4.6%). Rate of SPs was similar in FOBT-based cohorts as in colonoscopy screening cohorts. No apparent association between the rate of SP and gender or age was shown. Rate of SPS ranged from 0% to 0.5%, which increased to 0.4% to 0.8% after follow-up colonoscopy.
The detection rate of SPs is variable among screening cohorts, and standards for reporting, detection and histopathological assessment should be established. The median rate, as found in this study, may contribute to define uniform minimum standards for males and females between 50 and 75 years of age.
Plasma parcels are observed propagating from the Sun out to the large coronal heights monitored by the Heliospheric Imagers (HI) instruments onboard the NASA STEREO spacecraft during September 2007. ...The source region of these out‐flowing parcels is found to corotate with the Sun and to be rooted near the western boundary of an equatorial coronal hole. These plasma enhancements evolve during their propagation through the HI cameras' fields of view and only becoming fully developed in the outer camera field of view. We provide evidence that HI is observing the formation of a Corotating Interaction Region (CIR) where fast solar wind from the equatorial coronal hole is interacting with the slow solar wind of the streamer belt located on the western edge of that coronal hole. A dense plasma parcel is also observed near the footpoint of the observed CIR at a distance less than 0.1AU from the Sun where fast wind would have not had time to catch up slow wind. We suggest that this low‐lying plasma enhancement is a plasma parcel which has been disconnected from a helmet streamer and subsequently becomes embedded inside the corotating interaction region.
Intensification of grasslands is necessary to meet the increasing demand of livestock products. The application of nitrogen (N) on grasslands affects the N balance therefore the nitrogen use ...efficiency (NUE). Emissions of nitrous oxide (N2O) are produced due to N fertilisation and low NUE. These emissions depend on the type and rates of N applied. In this study we have compiled data from 5 UK N fertilised grassland sites (Crichton, Drayton, North Wyke, Hillsborough and Pwllpeiran) covering a range of soil types and climates. The experiments evaluated the effect of increasing rates of inorganic N fertiliser provided as ammonium nitrate (AN) or calcium ammonium nitrate (CAN). The following fertiliser strategies were also explored for a rate of 320 kg N ha−1: using the nitrification inhibitor dicyandiamide (DCD), changing to urea as an N source and splitting fertiliser applications. We measured N2O emissions for a full year in each experiment, as well as soil mineral N, climate data, pasture yield and N offtake. N2O emissions were greater at Crichton and North Wyke whereas Drayton, Hillsborough and Pwllpeiran had the smallest emissions. The resulting average emission factor (EF) of 1.12% total N applied showed a range of values for all the sites between 0.6 and 2.08%. NUE depended on the site and for an application rate of 320 kg N ha−1, N surplus was on average higher than 80 kg N ha−1, which is proposed as a maximum by the EU Nitrogen Expert Panel. N2O emissions tended to be lower when urea was applied instead of AN or CAN, and were particularly reduced when using urea with DCD. Finally, correlations between the factors studied showed that total N input was related to Nofftake and Nexcess; while cumulative emissions and EF were related to yield scaled emissions.
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•N2O emissions and NUE were measured at 5 UK grassland sites.•Different fertilisation rates and strategies were tested in all sites.•Average N2O emission factor was 1.12%, but ranged from 0.60% to 2.08%.•Using urea and urea with DCD reduced N2O emission factor.•Yield scaled emissions and emissions relative to herbage N content show similar trend.
Urine patches and dung pats from grazing livestock create hotspots for production and emission of the greenhouse gas, nitrous oxide (N2O), and represent a large proportion of total N2O emissions in ...many national agricultural greenhouse gas inventories. As such, there is much interest in developing country specific N2O emission factors (EFs) for excretal nitrogen (EF3, pasture, range and paddock) deposited during gazing. The aims of this study were to generate separate N2O emissions data for cattle derived urine and dung, to provide an evidence base for the generation of a country specific EF for the UK from this nitrogen source. The experiments were also designed to determine the effects of site and timing of application on emissions, and the efficacy of the nitrification inhibitor, dicyandiamide (DCD) on N2O losses. This co-ordinated set of 15 plot-scale, year-long field experiments using static chambers was conducted at five grassland sites, typical of the soil and climatic zones of grazed grassland in the UK. We show that the average urine and dung N2O EFs were 0.69% and 0.19%, respectively, resulting in a combined excretal N2O EF (EF3), of 0.49%, which is <25% of the IPCC default EF3 for excretal returns from grazing cattle. Regression analysis suggests that urine N2O EFs were controlled more by composition than was the case for dung, whilst dung N2O EFs were more related to soil and environmental factors. The urine N2O EF was significantly greater from the site in SW England, and significantly greater from the early grazing season urine application than later applications. Dycandiamide reduced the N2O EF from urine patches by an average of 46%. The significantly lower excretal EF3 than the IPCC default has implications for the UK's national inventory and for subsequent carbon footprinting of UK ruminant livestock products.
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•First co-ordinated experiments in UK to generate data for country specific grazing excretal N2O EF•Urine had a significantly greater average N2O EF (0.69%) than dung (0.19%).•The combined excretal N2O EF was 0.49%, <25% of the IPCC default value for cattle.•DCD reduced the N2O EF from urine patches by an average of 46%.•Urine N2O was controlled by its composition, dung N2O was related to soil and environmental factors.
Abstract
Solar active regions (ARs) play a fundamental role in driving many of the geoeffective eruptions, which propagate into the solar system. However, we are still unable to consistently predict ...where and when ARs will occur across the solar disk by identifying preemergence signatures in observables such as the Doppler velocity (without using helioseismic methods). Here we aim to determine the earliest time at which preemergence signatures, the horizontal divergent flow (HDF) in particular, can be confidently detected using data from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager. Initially, we follow previous studies using the thresholding method, which searches for significant increases in the number of pixels that display a specific line-of-sight velocity. We expand this method to more velocity windows and conduct a basic parameter study investigating the effect of cadence on the inferred results. Our findings agree with previous studies with 37.5% of ARs displaying an HDF, with average lead times between the HDF and flux emergence of 58 minutes. We present a new potential signature of flux emergence, which manifests as cadence-independent transient disruptions to the amplitudes of multiple velocity windows and recover potential preemergence signatures for 10 of the 16 ARs studied, with lead times of 60–156 minutes. Several effects can influence both the estimated times of both HDF and flux emergence suggesting that one may need to combine Doppler and magnetic field data to get a reliable indicator of continued flux emergence.
•The GHG contributions of shelterbelts in cultivated soils was investigated.•Compared to cultivated soils, N2O emissions were 4-times lower in the shelterbelts.•Soil CH4 oxidation potential was ...3.5-times greater in the shelterbelts.•Emissions of non-CO2 GHGs was reduced by 0.55MgCO2eha−1yr−1 in the shelterbelts.•Soil C storage was 27% greater in the shelterbelts than in the cultivated fields.
Farm shelterbelts are used as a management tool to reduce erosion, conserve moisture, protect crops and buildings, and sequester carbon. Although carbon storage in shelterbelts has been well researched, there have been no measurements of soil trace gas exchange in shelterbelts relative to cropped fields. Our objective was to quantify, for the first time, soil CO2, CH4 and N2O fluxes from shelterbelts and compare them to emissions from adjacent cropped fields to assess their potential for greenhouse gas (GHG) mitigation. During 2013 and 2014, non-steady state vented chambers were used to monitor soil GHG fluxes from nine shelterbelts and their associated cropped fields at three locations within the Boreal plains and Prairies Eco-zones of Saskatchewan Canada. Mean cumulative CO2 emissions from shelterbelt soils were significantly (P<0.0001) greater than those from cropped fields (i.e., 4.1 and 2.1Mg CO2-Cha−1yr−1, respectively). However, soil organic carbon (SOC) storage (0–30cm) was 27% greater – representing an increase of 28Mgha−1 – in the shelterbelts than in the cropped fields. Soil CH4 oxidation was greater (P<0.0001) in shelterbelts than in adjacent cropped fields (i.e., −0.66 and −0.19kgCH4-Cha−1yr−1, respectively) and cropped soils emitted significantly (P<0.0001) greater quantities of N2O than the shelterbelts (i.e., 2.5 and 0.65kgN2O-Nha−1yr−1, respectively). Total seasonal exchange of non-CO2 GHGs was reduced by 0.55MgCO2eha−1yr−1 in shelterbelts as compared with cropped fields, 98% of which was soil-derived N2O. Patterns of soil temperature, moisture and organic matter distribution beneath shelterbelts suggest a modification in soil micro-environment due to shelterbelt establishment and root activity that, in turn, may be responsible for the observed increase in soil CO2 emissions and CH4 oxidation. Our data demonstrate that shelterbelts have substantial potential to mitigate GHGs by enhancing C storage and reducing N2O emissions, while maintaining a strong CH4 sink.
To determine the incremental yield of standardized addition of chest CT to abdominal CT to detect COVID-19 in patients presenting with primarily acute gastrointestinal symptoms requiring abdominal ...imaging. Summary Background Data: Around 20% of patients with COVID-19 present with gastrointestinal symptoms. COVID-19 might be neglected in these patients, as the focus could be on finding abdominal pathology. During the COVID-19 pandemic, several centers have routinely added chest CT to abdominal CT to detect possible COVID-19 in patients presenting with gastrointestinal symptoms. However, the incremental yield of this strategy is unknown.
This multicenter study in 6 Dutch centers included consecutive adult patients presenting with acute nontraumatic gastrointestinal symptoms, who underwent standardized combined abdominal and chest CT between March 15, 2020 and April 30, 2020. All CT scans were read for signs of COVID-19 related pulmonary sequelae using the СО-RADS score. The primary outcome was the yield of high COVID-19 suspicion (СО-RADS 4-5) based on chest CT.
A total of 392 patients were included. Radiologic suspicion for COVID-19 (СО-RADS 4-5) was present in 17 (4.3%) patients, eleven of which were diagnosed with COVID-19. Only 5 patients with СО-RADS 4-5 presented without any respiratory symptoms and were diagnosed with COVID-19. No relation with community prevalence could be detected.
The yield of adding chest CT to abdominal CT to detect COVID-19 in patients presenting with acute gastrointestinal symptoms is extremely low with an additional detection rate of around 1%.
Understanding the adaptations that allow species to live in temporally variable environments is essential for predicting how they may respond to future environmental change. Variation at the ...intergenerational scale can allow the evolution of bet-hedging strategies: a novel genotype may be favoured over an alternative with higher arithmetic mean fitness if the new genotype experiences a sufficiently large reduction in temporal fitness variation; the successful genotype is said to have traded off its mean and variance in fitness in order to ‘hedge its evolutionary bets’. We review the evidence for bet-hedging in a range of simple plant systems that have proved particularly tractable for studying bet-hedging under natural conditions. We begin by outlining the essential theory, reiterating the important distinction between conservative and diversified bet-hedging strategies. We then examine the theory and empirical evidence for the canonical example of bet-hedging: diversification via dormant seeds in annual plants. We discuss the complications that arise when moving beyond this simple case to consider more complex life-history traits, such as flowering size in semelparous perennial plants. Finally, we outline a framework for accommodating these complications, emphasizing the central role that model-based approaches can play.
Increasing colonoscopy withdrawal time (CWT) is thought to be associated with increasing adenoma detection rate (ADR). Current English guidelines recommend a minimum CWT of 6 minutes. It is known ...that in the Bowel Cancer Screening Programme (BCSP) in England there is wide variation in CWT. The aim of this observational study was to examine the relationship between CWT and ADR.
The study examined data from 31 088 colonoscopies by 147 screening program colonoscopists. Colonoscopists were grouped in four levels of mean CWT ( < 7, 7 - 8.9, 9 - 10.9, and ≥ 11 minutes). Univariable and multivariable analysis (binary logistic and negative binomial regression) were used to explore the relationship between CWT, ADR, mean number of adenomas and number of right-sided and advanced adenomas.
In colonoscopists with a mean CWT < 7 minutes, the mean ADR was 42.5 % compared with 47.1 % in the ≥ 11-minute group (P < 0.001). The mean number of adenomas detected per procedure increased from 0.77 to 0.94, respectively (P < 0.001). The increase in adenoma detection was mainly of subcentimeter or proximal adenomas; there was no increase in the detection of advanced adenomas. Regression models showed an increase in ADR from 43 % to 46.5 % for mean CWT times ranging from 6 to 10 minutes.
This study demonstrates that longer mean withdrawal times are associated with increasing adenoma detection, mainly of small or right-sided adenomas. However, beyond 10 minutes the increase in ADR is minimal. Mean withdrawal times longer than 6 minutes are not associated with increased detection of advanced adenomas. Withdrawal time remains an important quality metric of colonoscopy.
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