Publications by authors named "Helen M Roberts"

14 Publications

  • Page 1 of 1

Nonlinear landscape and cultural response to sea-level rise.

Sci Adv 2020 Nov 4;6(45). Epub 2020 Nov 4.

Colossus, Pilot's Retreat, St Mary's, Isles of Scilly TR21 0PB, UK.

Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. While the change from land to sea represents a dramatic and permanent shift for preexisting human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socioeconomic change. Here, we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change, and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly nonlinear landscape and cultural responses to rising sea levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/sciadv.abb6376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673675PMC
November 2020

Reasons to be cheerful: the other global crisis.

BMJ 2020 07 3;370:m2627. Epub 2020 Jul 3.

UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmj.m2627DOI Listing
July 2020

Author Correction: 150,000-year palaeoclimate record from northern Ethiopia supports early, multiple dispersals of modern humans from Africa.

Sci Rep 2018 Dec 17;8(1):17993. Epub 2018 Dec 17.

Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-37595-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6297155PMC
December 2018

Implications of X-ray beam profiles on qualitative and quantitative synchrotron micro-focus X-ray fluorescence microscopy.

J Synchrotron Radiat 2018 Nov 28;25(Pt 6):1719-1726. Epub 2018 Sep 28.

Aston Institute of Materials Research, School of Engineering, University of Aston, Birmingham B4 7ET, UK.

Synchrotron radiation X-ray fluorescence microscopy is frequently used to investigate the spatial distribution of elements within a wide range of samples. Interrogation of heterogeneous samples that contain large concentration ranges has the potential to produce image artefacts due to the profile of the X-ray beam. The presence of these artefacts and the distribution of flux within the beam profile can significantly affect qualitative and quantitative analyses. Two distinct correction methods have been generated by referencing the beam profile itself or by employing an adaptive-thresholding procedure. Both methods significantly improve qualitative imaging by removing the artefacts without compromising the low-intensity features. The beam-profile correction method improves quantitative results but requires accurate two-dimensional characterization of the X-ray beam profile.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1107/S160057751801247XDOI Listing
November 2018

Research with children and young people: not on them. What can we learn from the non-clinical research?

Arch Dis Child 2019 10 31;104(10):936-937. Epub 2018 Oct 31.

PenCLAHRC Patient and Public Involvement Team, University of Exeter Medical School, Exeter, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/archdischild-2018-315925DOI Listing
October 2019

150,000-year palaeoclimate record from northern Ethiopia supports early, multiple dispersals of modern humans from Africa.

Sci Rep 2018 01 18;8(1):1077. Epub 2018 Jan 18.

Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK.

Climatic change is widely acknowledged to have played a role in the dispersal of modern humans out of Africa, but the timing is contentious. Genetic evidence links dispersal to climatic change ~60,000 years ago, despite increasing evidence for earlier modern human presence in Asia. We report a deep seismic and near-continuous core record of the last 150,000 years from Lake Tana, Ethiopia, close to early modern human fossil sites and to postulated dispersal routes. The record shows varied climate towards the end of the penultimate glacial, followed by an abrupt change to relatively stable moist climate during the last interglacial. These conditions could have favoured selection for behavioural versatility, population growth and range expansion, supporting models of early, multiple dispersals of modern humans from Africa.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-19601-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5773494PMC
January 2018

Impact of Bariatric Surgical Intervention on Peripheral Blood Neutrophil (PBN) Function in Obesity.

Obes Surg 2018 06;28(6):1611-1621

Periodontal Research Group, School of Dentistry, Institute of Clinical Science, University of Birmingham and Birmingham Dental Hospital (Birmingham Community Healthcare Trust), 5 Mill Pool Way, Edgbaston, Birmingham, B5 7ET, UK.

Aim: The aim of this study was to investigate the impact of weight loss following gastric band surgery on multiple measures of peripheral blood neutrophil (PBN) function.

Material And Methods: Twenty-three obese patients undergoing gastric band surgery were recruited to a longitudinal intervention study, alongside non-obese, healthy gender- and age-matched controls. Eighteen pairs of patients and controls completed all stages of the study. PBNs were isolated by density centrifugation and a comprehensive analysis of PBN function was undertaken at various stages of the patients' bariatric surgical care pathway.

Results: Obese patients exhibited exaggerated PBN activity in response to various stimuli, characterised by higher reactive oxygen species (ROS) generation (n = 18, p < 0.001) and release of pro-inflammatory cytokines (n = 10, p < 0.05) and lower PBN extracellular trap (NET) formation (n = 18, p < 0.01). PBN chemotactic accuracy was also impaired prior to surgery (n = 18, p < 0.01). Weight loss was associated with normalised NET production and lower ROS production and cytokine release relative to healthy controls. However, chemotactic accuracy remained impaired in patients.

Conclusions: Weight loss following gastric band surgery was associated with a decrease in the pro-inflammatory activities of peripheral blood neutrophils (PBNs). A hyper-inflammatory PBN phenotype, involving excess ROS and cytokine release, reduced NET formation and chemotaxis, may lead to a reduced ability to eliminate infection, alongside inflammation-mediated tissue damage in obese individuals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11695-017-3063-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5973997PMC
June 2018

Bureaucracy, trust and time: recruitment in a low-risk study of paediatric protocols forchildren who miss medicalappointments.

Arch Dis Child 2017 08 13;102(8):786-787. Epub 2017 May 13.

School of Social and Community Medicine, University of Bristol, Bristol, UK.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/archdischild-2017-313175DOI Listing
August 2017

Impact of fibrinogen carbamylation on fibrin clot formation and stability.

Thromb Haemost 2017 05 6;117(5):899-910. Epub 2017 Apr 6.

Veronika Binder, Broegelmann Research Laboratory, Department of Clinical Science, University of Bergen, The Laboratory Building, 5th floor, Bergen, Norway, Tel.: +47 55 97 46 48, Fax: +47 55 97 58 17, E-mail:

Carbamylation is a non-enzymatic post-translational modification induced upon exposure of free amino groups to urea-derived cyanate leading to irreversible changes of protein charge, structure and function. Levels of carbamylated proteins increase significantly in chronic kidney disease and carbamylated albumin is considered as an important biomarker indicating mortality risk. High plasma concentrations and long half-life make fibrinogen a prime target for carbamylation. As aggregation and cross-linking of fibrin monomers rely on lysine residues, it is likely that carbamylation impacts fibrinogen processing. In this study we investigated carbamylation levels of fibrinogen from kidney disease patients as well as the impact of carbamylation on fibrinogen cleavage by thrombin, fibrin polymerisation and cross-linking in vitro. In conjunction, all these factors determine clot structure and stability and thus control biochemical and mechanical properties. LC-MS/MS analyses revealed significantly higher homocitrulline levels in patient fibrinogen than in fibrinogen isolated from control plasma. In our in vitro studies we found that although carbamylation does not affect thrombin cleavage per se, it alters fibrin polymerisation kinetics and impairs cross-linking and clot degradation. In addition, carbamylated fibrin clots had reduced fiber size and porosity associated with decreased mechanical stability. Using mass spectroscopy, we discovered that N-terminally carbamylated fibrinopeptide A was generated in this process and acted as a strong neutrophil chemoattractant potentially mediating recruitment of inflammatory cells to sites of fibrin(ogen) turnover. Taken together, carbamylation of fibrinogen seems to play a role in aberrant fibrin clot formation and might be involved in haemostatic disorders associated with chronic inflammatory diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1160/TH16-09-0704DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442607PMC
May 2017

Effects of leukotoxin on neutrophil migration and extracellular trap formation.

J Oral Microbiol 2016 8;8:33070. Epub 2016 Nov 8.

Section Oral Microbiology, Department of Odontology, Umeå University, Umeå, Sweden.

Background: Aggressive periodontitis is associated with the presence of , a leukotoxin (Ltx)-producing periodontal pathogen. Ltx has the ability to lyse white blood cells including neutrophils.

Objectives: This study was aimed at investigating the interactions between neutrophils and Ltx with regard to the chemotactic properties of Ltx and the release of neutrophil extracellular traps (NETs).

Methods: Neutrophils from healthy blood donors were isolated and incubated for 30 min and 3 h with increasing concentrations of Ltx (1, 10, and 100 ng/mL) as well as with strains (NCTC 9710 and HK 1651) producing different levels of Ltx. Formation of NETs and cell lysis were assessed by microscopy, fluorescence-based assays, and measurement of released lactate dehydrogenase. Neutrophil migration in response to different Ltx gradients was monitored by real-time video microscopy, and image analysis was performed using ImageJ software.

Results: Although Ltx (10 and 100 ng/mL) and the leukotoxic strain HK 1651 lysed some neutrophils, other cells were still capable of performing NETosis in a concentration-dependent manner. Low doses of Ltx and the weakly leukotoxic strain NCTC 9710 did not lead to neutrophil lysis, but did induce some NETosis. Furthermore, all three concentrations of Ltx enhanced random neutrophil movement; however, low directional accuracy was observed compared with the positive control (fMLP).

Conclusions: The results indicate that Ltx acts both as a neutrophil activator and also causes cell death. In addition, Ltx directly induces NETosis in neutrophils prior to cell lysis. In future studies, the underlying pathways involved in Ltx-meditated neutrophil activation and NETosis need to be investigated further.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103672PMC
http://dx.doi.org/10.3402/jom.v8.33070DOI Listing
November 2016

Carbamylated LL-37 as a modulator of the immune response.

Innate Immun 2016 Apr 15;22(3):218-29. Epub 2016 Feb 15.

Broegelmann Research Laboratory, Department of Clinical Science, University of Bergen, Bergen, Norway Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland

Carbamylation of lysine residues and protein N-termini is an ubiquitous, non-enzymatic post-translational modification. Carbamylation at sites of inflammation is due to cyanate formation during the neutrophil oxidative burst and may target lysine residues within the antimicrobial peptide LL-37. The bactericidal and immunomodulatory properties of LL-37 depend on its secondary structure and cationic nature, which are conferred by arginine and lysine residues. Therefore, carbamylation may affect the biological functions of LL-37. The present study examined the kinetics and pattern of LL-37 carbamylation to investigate how this modification affects the bactericidal, cytotoxic and immunomodulatory function of the peptide. The results indicated that LL-37 undergoes rapid modification in the presence of physiological concentrations of cyanate, yielding a spectrum of diverse carbamylated peptides. Mass spectrometry analyses revealed that theN-terminal amino group of Leu-1 was highly reactive and was modified almost instantly by cyanate to generate the predominant form of the modified peptide, named LL-37(C1) This was followed by the sequential carbamylation of Lys-8, Lys-12, and Lys-15 to yield LL-37(C8), and Lys-15 to yield LL-37(C12,15) Carbamylation had profound and diverse effects on the structure and biological properties of LL-37. In some cases, anti-inflammatory LL-37 was rapidly converted to pro-inflammatory LL-37.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1753425916631404DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5143673PMC
April 2016

Time, monetary and other costs of participation in family-based child weight management interventions: qualitative and systematic review evidence.

PLoS One 2015 8;10(4):e0123782. Epub 2015 Apr 8.

University College London Institute of Child Health, London, United Kingdom.

Background: Childhood overweight and obesity have health and economic impacts on individuals and the wider society. Families participating in weight management programmes may foresee or experience monetary and other costs which deter them from signing up to or completing programmes. This is recognised in the health economics literature, though within this sparse body of work, costs to families are often narrowly defined and not fully accounted for. A societal perspective incorporating a broader array of costs may provide a more accurate picture. This paper brings together a review of the health economics literature on the costs to families attending child weight management programmes with qualitative data from families participating in a programme to manage child overweight and obesity.

Methods: A search identified economic evaluation studies of lifestyle interventions in childhood obesity. The qualitative work drew on interviews with families who attended a weight management intervention in three UK regions.

Results: We identified four cost-effectiveness analyses that include information on costs to families. These were categorised as direct (e.g. monetary) and indirect (e.g. time) costs. Our analysis of qualitative data demonstrated that, for families who attended the programme, costs were associated both with participation on the scheme and with maintaining a healthy lifestyle afterwards. Respondents reported three kinds of cost: time-related, social/emotional and monetary.

Conclusion: Societal approaches to measuring cost-effectiveness provide a framework for assessing the monetary and non-monetary costs borne by participants attending treatment programmes. From this perspective, all costs should be considered in any analysis of cost-effectiveness. Our data suggest that family costs are important, and may act as a barrier to the uptake, completion and maintenance of behaviours to reduce child obesity. These findings have implications for the development and implementation of child weight initiatives in particular, in relation to reducing inequalities in health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0123782PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4390145PMC
March 2016

Impaired neutrophil directional chemotactic accuracy in chronic periodontitis patients.

J Clin Periodontol 2015 Jan 8;42(1):1-11. Epub 2015 Jan 8.

Periodontal Research Group and MRC Centre for Immune Regulation, University of Birmingham, Birmingham, UK.

Aim: To investigate the chemotactic accuracy of peripheral blood neutrophils from patients with chronic periodontitis compared with matched healthy controls, before and after non-surgical periodontal therapy.

Material & Methods: Neutrophils were isolated from patients and controls (n = 18) by density centrifugation. Using the Insall chamber and video microscopy, neutrophils were analysed for directional chemotaxis towards N-formyl-methionyl-leucyl-phenylalanine [fMLP (10 nM), or CXCL8 (200 ng/ml)]. Circular statistics were utilized for the analysis of cell movement.

Results: Prior to treatment, neutrophils from patients with chronic periodontitis had significantly reduced speed, velocity and chemotactic accuracy compared to healthy controls for both chemoattractants. Following periodontal treatment, patient neutrophils continued to display reduced speed in response to both chemoattractants. However, velocity and accuracy were normalized for the weak chemoattractant CXCL8 while they remained significantly reduced for fMLP.

Conclusions: Chronic periodontitis is associated with reduced neutrophil chemotaxis, and this is only partially restored by successful treatment. Dysfunctional neutrophil chemotaxis may predispose patients with periodontitis to their disease by increasing tissue transit times, thus exacerbating neutrophil-mediated collateral host tissue damage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jcpe.12326DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340045PMC
January 2015

Worked examples of alternative methods for the synthesis of qualitative and quantitative research in systematic reviews.

BMC Med Res Methodol 2007 Jan 15;7. Epub 2007 Jan 15.

School for Policy Studies, University of Bristol, 8 Priory Rd, Bristol BS8 1TZ, UK.

Background: The inclusion of qualitative studies in systematic reviews poses methodological challenges. This paper presents worked examples of two methods of data synthesis (textual narrative and thematic), used in relation to one review, with the aim of enabling researchers to consider the strength of different approaches.

Methods: A systematic review of lay perspectives of infant size and growth was conducted, locating 19 studies (including both qualitative and quantitative). The data extracted from these were synthesised using both a textual narrative and a thematic synthesis.

Results: The processes of both methods are presented, showing a stepwise progression to the final synthesis. Both methods led us to similar conclusions about lay views toward infant size and growth. Differences between methods lie in the way they dealt with study quality and heterogeneity.

Conclusion: On the basis of the work reported here, we consider textual narrative and thematic synthesis have strengths and weaknesses in relation to different research questions. Thematic synthesis holds most potential for hypothesis generation, but may obscure heterogeneity and quality appraisal. Textual narrative synthesis is better able to describe the scope of existing research and account for the strength of evidence, but is less good at identifying commonality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1471-2288-7-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1783856PMC
January 2007