51 research outputs found

    Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques

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    Automated monitoring of freeze-thaw cycles and fracture propagation in mountain rockwalls is 23 needed to provide early warning about rockfall hazards. Conventional geoelectrical methods 24 such as electrical resistivity tomography (ERT) are limited by large and variable ohmic contact 25 resistances, requiring galvanic coupling with metal electrodes inserted into holes drilled into 26 rock, and which can be loosened by rock weathering. We report a novel experimental 27 methodology that combined capacitive resistivity imaging (CRI), ERT and microseismic event 28 recording to monitor freeze-thaw of six blocks of hard and soft limestones under conditions 29 simulating an active layer above permafrost and seasonally frozen rock in a non-permafrost 30 environment. Our results demonstrate that the CRI method is highly sensitive to freeze-thaw 31 processes; it yields property information equivalent to that obtained with conventional ERT and 32 offers a viable route for non-galvanic long-term geoelectrical monitoring, extending the benefits 33 of the methodology to soft/hard rock environments. Contact impedances achieved with CRI are 34 less affected by seasonal temperature changes, the aggregate state of the pore water (liquid or 35 frozen), and the presence of low-porosity rock with high matrix resistivities than those achieved 36 with ERT. Microseismic monitoring has the advantage over acoustic emissions that events were 37 recorded in relevant field distances of meters to decameters from cracking events. For the first 38 time we recorded about 1000 microcracking events and clustered them in four groups according 39 to frequency and waveform. Compared to previous studies, mainly on ice-cracking in glaciers, 40 the groups are attributed to single- or multiple-stage cracking events such as crack coalescence

    Diarylethene-Based Photoswitchable Inhibitors of Serine Proteases

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    A bicyclic peptide scaffold was chemically adapted to generate diarylethene-based photoswitchable inhibitors of serine protease Bos taurus trypsin 1 (T1). Starting from a prototype molecule—sunflower trypsin inhibitor-1 (SFTI-1)—we obtained light-controllable inhibitors of T1 with Ki in the low nanomolar range, whose activity could be modulated over 20-fold by irradiation. The inhibitory potency as well as resistance to proteolytic degradation were systematically studied on a series of 17 SFTI-1 analogues. The hydrogen bond network that stabilizes the structure of inhibitors and possibly the enzyme–inhibitor binding dynamics were affected by isomerization of the photoswitch. The feasibility of manipulating enzyme activity in time and space was demonstrated by controlled digestion of gelatin-based hydrogel and an antimicrobial peptide BP100-RW. Finally, our design principles of diarylethene photoswitches are shown to apply also for the development of other serine protease inhibitor

    Highly Fluorinated Peptide Probes with Enhanced In Vivo Stability for 19^{19}F‐MRI

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    A labeling strategy for in vivo 19^{19}F-MRI (magnetic resonance imaging) based on highly fluorinated, short hydrophilic peptide probes, is developed. As dual-purpose probes, they are functionalized further by a fluorophore and an alkyne moiety for bioconjugation. High fluorination is achieved by three perfluoro-tert-butyl groups, introduced into asparagine analogues by chemically stable amide bond linkages. d-amino acids and ÎČ-alanine in the sequences endow the peptide probes with low cytotoxicity and high serum stability. This design also yielded unstructured peptides, rendering all 27 19^{19}F substitutions chemically equivalent, giving rise to a single 19^{19}F-NMR resonance with <10 Hz linewidth. The resulting performance in 19^{19}F-MRI is demonstrated for six different peptide probes. Using fluorescence microscopy, these probes are found to exhibit high stability and long circulation times in living zebrafish embryos. Furthermore, the probes can be conjugated to bovine serum albumin with only amoderate increase in 19^{19}F-NMR linewidth to ≈30 Hz. Overall, these peptide probes are hence suitable for in vivo 19^{19}F-MRI applications

    Towards in vivo photomediated delivery of anticancer peptides: Insights from pharmacokinetic and -dynamic data

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    An in vivo study of a photoswitchable cytotoxic peptide LMB040 has been undertaken on a chemically induced hepatocellular carcinoma model in immunocompetent rats. We analysed the pharmacokinetic profile of the less toxic photoform (“ring-closed” dithienylethene) of the compound in tumors, plasma, and healthy liver. Accordingly, the peptide can reach a tumor concentration sufficiently high to exert a cytotoxic effect upon photoconversion into the more active (“ring-open”) photoform. Tissue morphology, histology, redox state of the liver, and hepatic biochemical parameters in blood serum were analysed upon treatment with (i) the less active photoform, (ii) the in vivo light-activated alternative photoform, and (iii) compared with a reference chemotherapeutic 5-fluorouracil. We found that application of the less toxic form followed by a delayed in vivo photoconversion into the more toxic ring-open form of LMB040 led to a higher overall survival of the animals, and signs of enhanced immune response were observed compared to the untreated animals

    Data standards can boost metabolomics research, and if there is a will, there is a way.

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    Thousands of articles using metabolomics approaches are published every year. With the increasing amounts of data being produced, mere description of investigations as text in manuscripts is not sufficient to enable re-use anymore: the underlying data needs to be published together with the findings in the literature to maximise the benefit from public and private expenditure and to take advantage of an enormous opportunity to improve scientific reproducibility in metabolomics and cognate disciplines. Reporting recommendations in metabolomics started to emerge about a decade ago and were mostly concerned with inventories of the information that had to be reported in the literature for consistency. In recent years, metabolomics data standards have developed extensively, to include the primary research data, derived results and the experimental description and importantly the metadata in a machine-readable way. This includes vendor independent data standards such as mzML for mass spectrometry and nmrML for NMR raw data that have both enabled the development of advanced data processing algorithms by the scientific community. Standards such as ISA-Tab cover essential metadata, including the experimental design, the applied protocols, association between samples, data files and the experimental factors for further statistical analysis. Altogether, they pave the way for both reproducible research and data reuse, including meta-analyses. Further incentives to prepare standards compliant data sets include new opportunities to publish data sets, but also require a little "arm twisting" in the author guidelines of scientific journals to submit the data sets to public repositories such as the NIH Metabolomics Workbench or MetaboLights at EMBL-EBI. In the present article, we look at standards for data sharing, investigate their impact in metabolomics and give suggestions to improve their adoption

    The effect of nurses' preparedness and nurse practitioner status on triage call management in primary care: a secondary analysis of cross-sectional data from the ESTEEM Trial

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    Background: Nurse-led telephone triage is increasingly used to manage demand for GP consultations in UK general practice. Previous studies are equivocal about the relationship between clinical experience and the call outcomes of nurse triage. Most research is limited to investigating nurse telephone triage in out-of-hours settings. Objective: To investigate whether the professional characteristics of primary care nurses undertaking computer decision supported software telephone triage are related to call disposition. Design: Questionnaire survey of nurses delivering the nurse intervention arm of the ESTEEM trial, to capture role type (practice nurse or nurse practitioner), prescriber status, number of years’ nursing experience, graduate status, previous experience of triage, and perceived preparedness for triage. Our main outcome was the proportion of triaged patients recommended for follow-up within the practice (call disposition), including all contact types (face-to-face, telephone or home visit), by a GP or nurse. Settings: : 15 General Practices and 7012 patients receiving the nurse triage intervention in four regions of the U.K. Participants: : 45 Nurse Practitioners (NPs) and Practice Nurse (PNs) trained in the use of CDSS. Methods: We investigated the associations between nursing characteristics and triage call disposition for patient ‘same-day’ appointment requests in general practice using multivariable logistic regression modelling. Results: Valid responses from 35 nurses (78%) from 14 practices: 31/35 (89%) had ≄10 years’ experience with 24/35 (69%) having ≄20 years. Most patient contacts (3842/4605; 86%) were recommended for follow-up within the practice. Nurse practitioners were less likely to recommend patients for follow-up odds ratio (OR) 0.19, 95% confidence interval (CI) 0.07; 0.49 than practice nurses. Nurses who reported that their previous experience had prepared them less well for triage were more likely to recommend patients for follow-up (OR 3.17, 95% CI 1.18; 5.55). Conclusion: Nurse characteristics were associated with disposition of triage calls to within practice follow-up. Nurse practitioners or those who reported feeling ‘more prepared’ for the role were more likely to manage the call definitively. Practices considering nurse triage should ensure that nurses transitioning into new roles feel adequately prepared. While standardised training is necessary, it may not be sufficient to ensure successful implementation

    Extension of the Segatella copri complex to 13 species with distinct large extrachromosomal elements and associations with host conditions

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    The Segatella copri (formerly Prevotella copri) complex (ScC) comprises taxa that are key members of the human gut microbiome. It was previously described to contain four distinct phylogenetic clades. Combining targeted isolation with large-scale metagenomic analysis, we defined 13 distinct Segatella copri-related species, expanding the ScC complex beyond four clades. Complete genome reconstruction of thirteen strains from seven species unveiled the presence of genetically diverse large circular extrachromosomal elements. These elements are consistently present in most ScC species, contributing to intra- and inter-species diversities. The nine species-level clades present in humans display striking differences in prevalence and intraspecies genetic makeup across human populations. Based on a meta-analysis, we found reproducible associations between members of ScC and the male sex and positive correlations with lower visceral fat and favorable markers of cardiometabolic health. Our work uncovers genomic diversity within ScC, facilitating a better characterization of the human microbiome

    Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

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    The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers
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