309 research outputs found
The Universal Cloud and Aerosol Sounding System (UCASS): a low-cost miniature optical particle counter for use in dropsonde or balloon-borne sounding systems
© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. An earlier version of this work was published in Atmospheric Measurement Techniques Discussions: https://dx.doi.org/10.5194/amt-2019-70.A low-cost miniaturized particle counter has been developed by The University of Hertfordshire (UH) for the measurement of aerosol and droplet concentrations and size distributions. The Universal Cloud and Aerosol Sounding System (UCASS) is an optical particle counter (OPC), which uses wide-angle elastic light scattering for the high-precision sizing of fluid-borne particulates. The UCASS has up to 16 configurable size bins, capable of sizing particles in the range 0.4–40 µm in diameter. Unlike traditional particle counters, the UCASS is an open-geometry system that relies on an external air flow. Therefore, the instrument is suited for use as part of a dropsonde, balloon-borne sounding system, as part of an unmanned aerial vehicle (UAV), or on any measurement platform with a known air flow. Data can be logged autonomously using an on-board SD card, or the device can be interfaced with commercially available meteorological sondes to transmit data in real time. The device has been deployed on various research platforms to take measurements of both droplets and dry aerosol particles. Comparative results with co-located instrumentation in both laboratory and field settings show good agreement for the sizing and counting ability of the UCASS.Peer reviewe
Identification of a Core Bacterial Community within the Large Intestine of the Horse
The horse has a rich and complex microbial community within its gastrointestinal tract that plays a central role in both health and disease. The horse receives much of its dietary energy through microbial hydrolysis and fermentation of fiber predominantly in the large intestine/hindgut. The presence of a possible core bacterial community in the equine large intestine was investigated in this study. Samples were taken from the terminal ileum and 7 regions of the large intestine from ten animals, DNA extracted and the V1-V2 regions of 16SrDNA 454-pyrosequenced. A specific group of OTUs clustered in all ileal samples and a distinct and different signature existed for the proximal regions of the large intestine and the distal regions. A core group of bacterial families were identified in all gut regions with clear differences shown between the ileum and the various large intestine regions. The core in the ileum accounted for 32% of all sequences and comprised of only seven OTUs of varying abundance; the core in the large intestine was much smaller (5-15% of all sequences) with a much larger number of OTUs present but in low abundance. The most abundant member of the core community in the ileum was Lactobacillaceae, in the proximal large intestine the Lachnospiraceae and in the distal large intestine the Prevotellaceae. In conclusion, the presence of a core bacterial community in the large intestine of the horse that is made up of many low abundance OTUs may explain in part the susceptibility of horses to digestive upset
Changes in the total fecal bacterial population in individual horses maintained on a restricted diet over 6 weeks
Twelve mature (aged 5–16 years) horses and ponies of mixed breed and type were fed restricted (1.25% BM Dry matter) quantities of one of two fiber based diets formulated to be iso-caloric. Diet 1 comprised of 0.8% body mass (BM) of chaff based complete feed plus 0.45% BM low energy grass hay (the same hay used for both diets). Diet 2 comprised 0.1% BM of a nutrient balancer plus 1.15% BM grass hay. Fecal samples were collected at week 10 and week 16. DNA was extracted and the V1-V2 regions of 16SrDNA were 454-pyrosequenced to investigate the bacterial microbiome of the horse. The two most abundant phyla found in both diets and sampling periods were the Firmicutes and Bacteroidetes. There was a clear reduction in Bacteroidetes with a concordant increase in Firmicutes over time. There was a limited degree of stability within the bacterial community of the hindgut of horses, with 65% of bacteria retained, over a 6 week period whilst on a uniform diet. The presence of a core community defined by being present in all samples (each animal/diet combination) included in the study and being present at 0.1% relative abundance (or greater) was identified. In total 65 operational taxonomic units (OTUs) were identified that fit the definition of core making up 21–28% of the total sequences recovered. As with total population the most abundant phyla were the Bacteroidetes followed by the Firmicutes, however there was no obvious shift in phyla due to period. Indeed, when the relative abundance of OTUs was examined across diets and periods there was no significant effect of diet or period alone or in combination on the relative abundance of the core OTUs
Helicobacter pylori prevalence in non-ulcer dyspepsia ethnic and socio-economic differences
Helicobacter pylori is an important cause of gastritis and a number of therapeutic. trials suggest that it may be important in the genesis of duodenal ulcer recurrence. The reported prevalence of gastric colonisation by the organism varies considerably. The aiIn of this cross-sectional survey was to determine its prevalence in non-ulcer dyspeptics and to determine whether this is influenced by age, race, sex, socio-economic status, educational level and the nwnber of persons sharing accommodation. One hundred and sixty-nine patients underwent endoscopy; biopsy speciInens were taken from the antrwn and H. pylori status was determined histologically. Gastric colonisation was found in 106 patients (63%). The prevalence showed a marked ethnic difference: 40% in whites and 71% in coloureds (P < 0,001). The ethnic groups were characterised by significant differences in socio-economic status (P < 10-6), educational level (P < 10-6), number of persons sharing accommodation (P < 10-6 ) and age (P < 0,001). These same differences were found when comparing the H. pylori-positive and negative groups, but were less marked and could be attributed to the marked differences between ethnic groups. We conclude that H. pylori prevalence differs between the ethnic groups studied. This may be because of varying degrees of exposure risk
C-reactive protein predicts further ischemic events in patients with transient ischemic attack or lacunar stroke
Patients who have experienced a first cerebral ischemic event are at increased risk of recurrent stroke. There is strong evidence that low-level inflammation as measured by high sensitivity C-reactive protein (hs-CRP) is a predictor of further ischemic events. Other mechanisms implicated in the pathogenesis of stroke may play a role in determining the risk of secondary events, including oxidative stress and the adaptive response to it and activation of neuroprotective pathways by hypoxia, for instance through induction of erythropoietin (EPO). This study investigated the association of the levels of CRP, peroxiredoxin 1 (PRDX1, an indicator of the physiological response to oxidative stress) and EPO (a neuroprotective factor produced in response to hypoxia) with the risk of a second ischemic event. Eighty patients with a diagnosis of lacunar stroke or transient ischemic attack (TIA) were included in the study and a blood sample was collected within 14 days from the initial event. Hs-CRP, PRDX1 and EPO were measured by ELISA. Further ischemic events were recorded with a mean follow-up of 42 months (min 24, max 64). Multivariate analysis showed that only CRP was an independent predictor of further events with an observed risk (OR) of 1.14 (P = 0.034, 95% CI 1.01-1.29). No association was observed with the levels of PRDX1 or EPO. A receiver operating curve (ROC) determined a cut-off CRP level of 3.25 ÎĽg/ml, with a 46% sensitivity and 81% specificity. Low-level inflammation as detected by hs-CRP is an independent predictor of recurrent cerebrovascular ischemic events
Tutorial on model selection and validation of model input into precision dosing software for model-informed precision dosing
There has been rising interest in using model-informed precision dosing to provide personalized medicine to patients at the bedside. This methodology utilizes population pharmacokinetic models, measured drug concentrations from individual patients, pharmacodynamic biomarkers, and Bayesian estimation to estimate pharmacokinetic parameters and predict concentration-time profiles in individual patients. Using these individualized parameter estimates and simulated drug exposure, dosing recommendations can be generated to maximize target attainment to improve beneficial effect and minimize toxicity. However, the accuracy of the output from this evaluation is highly dependent on the population pharmacokinetic model selected. This tutorial provides a comprehensive approach to evaluating, selecting, and validating a model for input and implementation into a model-informed precision dosing program. A step-by-step outline to validate successful implementation into a precision dosing tool is described using the clinical software platforms Edsim++ and MwPharm++ as examples.</p
Identification and Characterization of Three Novel Lipases Belonging to Families II and V from Anaerovibrio lipolyticus 5ST
Following the isolation, cultivation and characterization of the rumen bacterium Anaerovibrio lipolyticus in the 1960s, it has been recognized as one of the major species involved in lipid hydrolysis in ruminant animals. However, there has been limited characterization of the lipases from the bacterium, despite the importance of understanding lipolysis and its impact on subsequent biohydrogenation of polyunsaturated fatty acids by rumen microbes. This study describes the draft genome of Anaerovibrio lipolytica 5ST, and the characterization of three lipolytic genes and their translated protein. The uncompleted draft genome was 2.83 Mbp and comprised of 2,673 coding sequences with a G+C content of 43.3%. Three putative lipase genes, alipA, alipB and alipC, encoding 492-, 438- and 248- amino acid peptides respectively, were identified using RAST. Phylogenetic analysis indicated that alipA and alipB clustered with the GDSL/SGNH family II, and alipC clustered with lipolytic enzymes from family V. Subsequent expression and purification of the enzymes showed that they were thermally unstable and had higher activities at neutral to alkaline pH. Substrate specificity assays indicated that the enzymes had higher hydrolytic activity against caprylate (C8), laurate (C12) and myristate (C14)
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