Recent Submissions

  • Ex-vivo recellularisation and stem cell differentiation of a decellularised rat dental pulp matrix

    Matoug-Elwerfelli, M.; Nazzal, H.; Raif, E.M.; Wilshaw, Stacy-Paul; Esteves, F.; Duggal, M. (2020-12)
    Implementing the principles of tissue engineering within the clinical management of non-vital immature permanent teeth is of clinical interest. However, the ideal scaffold remains elusive. The aim of this work was to assess the feasibility of decellularising rat dental pulp tissue and evaluate the ability of such scaffold to support stem cell repopulation. Rat dental pulps were retrieved and divided into control and decellularised groups. The decellularisation protocol incorporated a low detergent concentration and hypotonic buffers. After decellularisation, the scaffolds were characterised histologically, immunohistochemistry and the residual DNA content quantified. Surface topography was also viewed under scanning electron microscopy. Biocompatibility was evaluated using cytotoxicity assays utilising L-929 cell line. Decellularised scaffolds were recellularised with human dental pulp stem cells up to 14 days in vitro. Cellular viability was assessed using LIVE/DEAD stain kit and the recellularised scaffolds were further assessed histologically and immunolabelled using makers for odontoblastic differentiation, cytoskeleton components and growth factors. Analysis of the decellularised scaffolds revealed an acellular matrix with histological preservation of structural components. Decellularised scaffolds were biocompatible and able to support stem cell survival following recellularisation. Immunolabelling of the recellularised scaffolds demonstrated positive cellular expression against the tested markers in culture. This study has demonstrated the feasibility of developing a biocompatible decellularised dental pulp scaffold, which is able to support dental pulp stem cell repopulation. Clinically, decellularised pulp tissue could possibly be a suitable scaffold for use within regenerative (reparative) endodontic techniques.
  • Förster resonance energy transfer in fluorophore labeled poly(2-ethyl-2-oxazoline)s†

    Merckx, R.; Swift, Thomas; Rees, R.; Van Guyse, J.F.R.; Schoolaert, E.; De Clerck, K.; Thienpont, H.; Jerca, V.V. (Royal Society of Chemistry, 2020)
    Dye-functionalized polymers have been extensively studied to understand polymer chain dynamics, intra or inter-molecular association and conformational changes as well as in practical applications such as signal amplification in diagnostic tests and light-harvesting antennas. In this work, the Förster resonance energy transfer (FRET) of dye-functionalized poly(2-ethyl-2-oxazoline) (PEtOx) was studied to evaluate the effect of dye positioning and polymer chain length on the FRET efficiency. Therefore, both α (initiating terminus)- or ω (terminal chain end)-fluorophore single labeled and dual α,ω-fluorescent dye labeled PEtOx were prepared via cationic ring opening polymerization (CROP) using 1-(bromomethyl)pyrene as the initiator and/or 1-pyrenebutyric acid or coumarin 343 as the terminating agent, yielding well-defined PEtOx with high labeling efficiency (over 91%). Fluorescence studies revealed that intramolecular FRET is most efficient for heterotelechelic PEtOx containing both pyrene and coumarin 343 fluorophores as chain ends, as expected. A strong dependence of the energy transfer on the chain length was found for these dual labeled polymers. The polymers were tested in both dilute organic (chloroform) and aqueous media revealing a higher FRET efficiency in water due to the enhanced emissive properties of pyrene. The application of dual labeled polymers as fluorescent probes for temperature sensing was demonstrated based on the lower critical solution temperature behavior of the PEtOx. Furthermore, these polymers could be successfully processed into fibers and thin films. Importantly, the fluorescence properties were retained in the solid state without decreasing the FRET efficiency, thus opening future possibilities for application of these materials in solar cells and/or sensors.
  • Branched amphotericin functional poly(N-isopropyl acrylamide): an antifungal polymer

    Swift, Thomas; Caseley, Emily; Pinnock, A.; Shepherd, J.; Shivshetty, N.; Garg, P.; Ian Douglas, C.W.; MacNeil, S.; Rimmer, Stephen (2021-01-27)
    Branched poly(N-isopropylacrylamide) was functionalized with Amphotericin B (AmB) at the chain ends to produce an antifungal material. The polymer showed antifungal properties against AmB-sensitive strains of Candida albicans, Fusarium keratoplasticum and Aspergillus flavus (minimal inhibitory concentration ranged from 5 to 500 µg ml−1) but was not effective against an AmB resistant strain of C. albicans nor against Candida tropicalis. The polymer end groups bound to the AmB target, ergosterol, and the fluorescence spectrum of a dye used as a solvatochromic probe, Nile red, was blue shifted indicating that segments of the polymer became desolvated on binding. The polymer was less toxic to corneal and renal epithelial cells and explanted corneal tissue than the free drug. Also, the polymer did not induce reactive oxygen species release from peripheral blood mononuclear cells, nor did it cause a substantial release of the proinflammatory cytokines, tumour necrosis factor-α and interleukin-1β (at 0.5 mg ml−1).
  • Fabrication of 3D hybrid scaffold by combination technique of electrospinning-like and freeze-drying to create mechanotransduction signals and mimic extracellular matrix function of skin

    Aghmiuni, A.I.; Heidari Keshel, S.; Sefat, Farshid; AkbarzadehKhiyavi, A. (2021-01)
    Fabrication of extracellular matrix (ECM)-like scaffolds (in terms of structural-functional) is the main challenge in skin tissue engineering. Herein, inspired by macromolecular components of ECM, a novel hybrid scaffold suggested which includes silk/hyaluronan (SF/HA) bio-complex modified by PCP: [polyethylene glycol/chitosan/poly(ɛ-caprolactone)] copolymer containing collagen to differentiate human-adipose-derived stem cells into keratinocytes. In followed by, different weight ratios (wt%) of SF/HA (S1:100/0, S2:80/20, S3:50/50) were applied to study the role of SF/HA in the improvement of physicochemical and biological functions of scaffolds. Notably, the combination of electrospinning-like and freeze-drying methods was also utilized as a new method to create a coherent 3D-network. The results indicated this novel technique was led to ~8% improvement of the scaffold's ductility and ~17% decrease in mean pore diameter, compared to the freeze-drying method. Moreover, the increase of HA (>20wt%) increased porosity to 99%, however, higher tensile strength, modulus, and water absorption% were related to S2 (38.1, 0.32 MPa, 75.3%). More expression of keratinocytes along with growth pattern similar to skin was also observed on S2. This study showed control of HA content creates a microporous-environment with proper modulus and swelling%, although, the role of collagen/PCP as base biocomposite and fabrication technique was undeniable on the inductive signaling of cells. Such a scaffold can mimic skin properties and act as the growth factor through inducing keratinocytes differentiation.
  • Soil fungal networks maintain local dominance of ectomycorrhizal trees

    Liang, M.; Johnson, D.; Burslem, D.F.R.P.; Yu, S.; Fang, M.; Taylor, Joe D.; Taylor, A.F.S.; Helgason, T.; Liu, X. (2020-05)
    The mechanisms regulating community composition and local dominance of trees in species-rich forests are poorly resolved, but the importance of interactions with soil microbes is increasingly acknowledged. Here, we show that tree seedlings that interact via root-associated fungal hyphae with soils beneath neighbouring adult trees grow faster and have greater survival than seedlings that are isolated from external fungal mycelia, but these effects are observed for species possessing ectomycorrhizas (ECM) and not arbuscular mycorrhizal (AM) fungi. Moreover, survival of naturally-regenerating AM seedlings over ten years is negatively related to the density of surrounding conspecific plants, while survival of ECM tree seedlings displays positive density dependence over this interval, and AM seedling roots contain greater abundance of pathogenic fungi than roots of ECM seedlings. Our findings show that neighbourhood interactions mediated by beneficial and pathogenic soil fungi regulate plant demography and community structure in hyperdiverse forests.
  • Diverse groups of fungi are associated with plastics in the surface waters of the Western South Atlantic and the Antarctic Peninsula

    Lacerda, A.L.d.F.; Proietti, M.C.; Secchi, E.R.; Taylor, Joe D. (2020-05)
    Marine plastic pollution has a range of negative impacts for biota and the colonization of plastics in the marine environment by microorganisms may have significant ecological impacts. However, data on epiplastic organisms, particularly fungi, is still lacking for many ocean regions. To evaluate plastic associated fungi and their geographic distribution, we characterised plastics sampled from surface waters of the western South Atlantic (WSA) and Antarctic Peninsula (AP), using DNA metabarcoding of three molecular markers (ITS2, 18S rRNA V4 and V9 regions). Numerous taxa from eight fungal phyla and a total of 64 orders were detected, including groups that had not yet been described associated with plastics. There was a varied phylogenetic assemblage of predominantly known saprotrophic taxa within the Ascomycota and Basidiomycota. We found a range of marine cosmopolitan genera present on plastics in both locations, i.e., Aspergillus, Cladosporium, Wallemia and a number of taxa unique to each region, as well as a high variation of taxa such as Chytridiomycota and Aphelidomycota between locations. Within these basal fungal groups we identified a number of phylogenetically novel taxa. This is the first description of fungi from the Plastisphere within the Southern Hemisphere, and highlights the need to further investigate the potential impacts of plastic associated fungi on other organisms and marine ecosystems.
  • Patient experience and physiological response to two commercially available daily disposable myopia control contact lenses

    Ghorbani Mojarrad, Neema; Cargill, C.; Collard, S.; Terry, L. (2021)
    Background: A range of myopia management (MM) contact lenses are becoming available to practitioners. These lenses are designed to slow myopia progression and axial elongation. This study explored the initial experience of participants wearing daily disposable MM contact lenses to investigate established factors previously associated with successful lens wear. Methods: This was a prospective, double-masked, crossover study. Twenty participants aged 18–30 years old were assigned to wear two daily disposable MM lenses in a randomised order. Visual acuity, contrast sensitivity, and amplitude/lag of accommodation were assessed at baseline, post-insertion, and after 2 and 6 h of lens wear. Self-reported lens comfort and vision quality were recorded at the same timepoints, and at 10 h post-insertion. Pairwise comparisons were performed between the two lenses at each timepoint, as well as assessing changes throughout wear. The relationship of the measured parameters to overall lens satisfaction was also assessed. Results: There were no significant differences between the two MM lenses at any timepoint for any of the participant-reported parameters, including overall satisfaction. A small difference in visual acuity was noted at 6 h post-insertion, although this is unlikely to be clinically significant. Comfort decreased throughout the day, most notably at 10 h post-insertion. A moderate positive correlation was observed between participant-reported visual quality and overall satisfaction. A similar pattern was seen for comfort and overall satisfaction. Self-reported vision quality and measured visual acuity were poorly correlated, highlighting the benefit of subjectively assessing the quality of vision with these lenses. Conclusions: The participants demonstrated comparable measures across a range of measures between the two MM lenses. Notably, half of the participants demonstrated a clear lens preference, although the preferred lens varied between individuals. Candidates for MM may benefit from trialling more than one MM lens design, to maximise initial wearing satisfaction.
  • Organic residue analysis of Early Neolithic 'bog pots' from Denmark demonstrates the processing of wild and domestic foodstuffs

    Robson, H.K.; Saul, H.; Steele, Valerie J.; Meadows, J.; Nielsen, P.O.; Fischer, A.; Heron, Carl P.; Craig, O.E. (Elsevier, 2021-04)
    Ceramic containers, intentionally deposited into wetlands, offer detailed insights into Early Neolithic culinary practices. Additionally, they are key for ascertaining the Neolithisation process in Denmark since they appear to form a typo-chronological sequence. Here, we use a combination of organic residue analysis (ORA) of pottery alongside Bayesian chronological modelling of the radiocarbon dates obtained on these vessels to explore the initial stages of votive deposition in wetlands, a practice that stretches from the Mesolithic to the onset of Christianity in Northern Europe. We consider 34 Early-Middle Neolithic (c. 3900–2350 cal BC) ‘bog pots’ from Denmark, of which 20 have ORA data, and 26 have been dated directly. Carbonised surface residues and absorbed lipids from powdered sherds were analysed using a combination of bulk carbon and nitrogen stable isotope analysis, gas chromatography-mass spectrometry (GC–MS) and GC-combustion-isotope ratio MS (GC-C-IRMS). The molecular and isotopic compositions of the analysed samples revealed the presence of aquatic, ruminant carcass and dairy fats as well as plant waxes with the majority containing mixtures thereof. Dairy fats were present from the onset of the Funnel Beaker culture, whilst aquatic foods, prevalent at the close of the preceding Mesolithic period, continued to be processed in pottery for the following thousand years.
  • PI3K inhibition as a novel therapeutic strategy for neoadjuvant chemoradiotherapy resistant oesophageal adenocarcinoma

    Edge, S.D.; Renard, I.; Pyne, E.; Moody, Hannah; Roy, R.; Beavis, A.W.; Archibald, S.J.; Cawthorne, C.J.; Maher, S.G.; Pires, I.M. (2021-01)
    Neoadjuvant chemoradiotherapy (neo-CRT) prior to surgery is the standard of care for oesophageal adenocarcinoma (OAC) patients. Unfortunately, most patients fail to respond to treatment. MiR-187 was previously shown to be downregulated in neo-CRT non-responders, whist in vitro miR-187 overexpression enhanced radiosensitivity and upregulated PTEN. This study evaluates the role of miR-187 and downstream PI3K signalling in radiation response in OAC. The effect of miR-187 overexpression on downstream PI3K signalling was evaluated in OAC cell lines by qPCR and Western blotting. PTEN expression was analysed in OAC pre-treatment biopsies of neo-CRT responders and non-responders. Pharmacological inhibition of PI3K using GDC-0941 was evaluated in combination with radiotherapy in two-dimensional and three-dimensional OAC models in vitro and as a single agent in vivo. Radiation response in vitro was assessed via clonogenic assay. PTEN expression was significantly decreased in neo-CRT non-responders. MiR-187 overexpression significantly upregulated PTEN expression and inhibited downstream PI3K signalling in vitro. GDC-0941 significantly reduced viability and enhanced radiation response in vitro and led to tumour growth inhibition as a single agent in vivo. Targeting of PI3K signalling is a promising therapeutic strategy for OAC patients who have repressed miR-187 expression and do not respond to conventional neo-CRT. This is the first study evaluating the effect of PI3K inhibition on radiosensitivity in OAC, with a particular focus on patients that do not respond to neo-CRT. We have shown for the first time that targeting of PI3K signalling is a promising alternative therapeutic strategy for OAC patients who do not respond to conventional neo-CRT.
  • Computational Studies of Lipid-Wrapped Gold Nanoparticle Transport Through Model Lung Surfactant Monolayers

    Hossain, S.I.; Gandhi, N.S.; Hughes, Zak E.; Saha, S.C. (2021-02-02)
    Colloidal nanoparticles, such as gold nanoparticles (AuNPs), are promising materials for the delivery of hydrophilic drugs via the pulmonary route. The inhaled nanoparticle drug carriers primarily deposit in lung alveoli and interact with the alveolar surface known as lung surfactants. Therefore, it is vital to understand the interactions of nanocarriers with the surfactant layer. To understand the interactions at the molecular level, here we simulated model lung surfactant monolayers with phospholipid (PL)-wrapped AuNPs at the vacuum-water interface using coarse-grained molecular dynamics simulations. The PL-wrapped AuNPs quickly adsorbed into the surfactant layer, altered the structural properties of the monolayer, and at high concentrations initiated the compressed monolayer to collapse/buckle. Among the surfactant monolayer lipid components, cholesterol adsorbed to the AuNPs preferentially over PL species. The position of the adsorbed PL-AuNPs within the monolayer, and subsequent monolayer perturbation, vary depending on the monolayer phase, monolayer composition, and species of PL used as a ligand. Information provided by these molecular dynamic simulations helps to rationalize why some colloidal nanoparticles work better as nanocarriers than others and aid the design of new ones, to avoid biological toxicity and improve efficacy for pulmonary drug delivery.
  • Progress towards a clinically-successful ATR inhibitor for cancer therapy

    Barnieh, Francis M.; Loadman, Paul M.; Falconer, Robert A. (2021-02)
    The DNA damage response (DDR) is now known to play an important role in both cancer development and its treatment. Targeting proteins such as ATR (Ataxia telangiectasia mutated and Rad3-related) kinase, a major regulator of DDR, has demonstrated significant therapeutic potential in cancer treatment, with ATR inhibitors having shown anti-tumour activity not just monotherapies, but also in potentiating the effects of conventional chemotherapy, radiotherapy, and immunotherapy. This review focuses on the biology of ATR, its functional role in cancer development and treatment, and the rationale behind inhibition of this target as a therapeutic approach, including evaluation of the progress and current status of development of potent and specific ATR inhibitors that have emerged in recent decades. The current applications of these inhibitors both in preclinical and clinical studies either as single agents or in combinations with chemotherapy, radiotherapy and immunotherapy are also extensively discussed. This review concludes with some insights into the various concerns raised or observed with ATR inhibition in both the preclinical and clinical settings, with some suggested solutions.
  • An assay for quantitative analysis of polysialic acid expression in cancer cells

    Guo, Xiaoxiao; Elkashef, Sara M.; Patel, Anjana; Ribeiro Morais, G.; Shnyder, Steven D.; Loadman, Paul M.; Patterson, Laurence H.; Falconer, Robert A. (2021-05-01)
    Polysialic acid (polySia) is a linear polysaccharide comprised of N-acetylneuraminic acid residues and its over-expression in cancer cells has been correlated with poor clinical prognosis. An assay has been developed for quantitative analysis of cellular polySia expression. This was achieved by extracting and purifying released polySia from glycoproteins by mild acid hydrolysis and optimised organic extraction. The polySia was further hydrolysed into Sia monomers, followed by fluorescent labelling and quantitative analysis. The assay was qualified utilising endoneuraminidase-NF to remove polySia from the surface of C6-ST8SiaII cancer cells (EC50 = 2.13 ng/ml). The result was comparable to that obtained in a polySia-specific cellular ELISA assay. Furthermore, the assay proved suitable for evaluation of changes in polySia expression following treatment with a small molecule inhibitor of polysialylation. Given the importance of polySia in multiple disease states, notably cancer, this is a potentially vital tool with applications in the fields of drug discovery and glycobiology.
  • Is the pen mightier than the sword? Exploring urban and rural health in Victorian England and Wales using the Registrar General Reports

    Crane-Kramer, G.M.M.; Buckberry, Jo (Springer, 2020-11)
    In AD 1836, the General Register Office (GRO) was established to oversee the national system of civil registration in England and Wales, recording all births, deaths and marriages. Additional data regarding population size, division size and patterns of occupation within each division permit urban and rural areas (and those with both urban and rural characteristics, described here as ‘mixed’) to be directly compared to each other. The annual Reports of the Registrar General summarize the collected data, including cause of and age at death, which is of particular value to historical demographers and bioarcheologists, allowing us to investigate demographic patterns in urban and rural districts in the nineteenth century. Overall, this paper aims to highlight how this documentary evidence can supplement osteological and paleopathological data to investigate how urbanization affected the health of past populations. It examines the data contained within the first Registrar General report (for 1837-8), in order to assess patterns of mortality of diverse rural, urban, and mixed populations within England and Wales at a point in time during a period of rapid urbanization. It shows that urban and mixed districts typically had lower life expectancy and different patterns in cause of death compared to rural areas. The paper briefly compares how the documentary data differs from information regarding health from skeletal populations, focusing on the city of London, highlighting that certain age groups (the very young and very old) are typically underrepresented in archeological assemblages and reminding us that, while the paleopathological record offers much in terms of chronic health, evidence of acute disease and importantly cause of death can rarely be ascertained from skeletal remains.
  • Dermal adipose tissue secretes HGF to promote human hair growth and pigmentation

    Nicu, C.; O'Sullivan, J.D.B.; Ramos, R.; Timperi, L.; Lai, T.; Farjo, N.; Farjo, B.; Pople, J.; Bhogal, R.; Hardman, J.A.; et al. (2021)
    Hair follicles (HFs) are immersed within dermal white adipose tissue (dWAT), yet human adipocyte-HF communication remains unexplored. Therefore, we investigated how perifollicular adipocytes affect the physiology of organ-cultured human anagen scalp HFs. Quantitative (immuno-)histomorphometry, microCT and transmission electron microscopy showed that the number and size of perifollicular adipocytes declined during anagen-catagen transition, whilst fluorescence lifetime imaging revealed increased lipid oxidation in adipocytes surrounding the bulge/sub-bulge region. Ex vivo, dWAT significantly stimulated hair matrix keratinocyte proliferation and HF pigmentation. Both dWAT pericytes and PREF1/DLK1+ adipocyte progenitors secreted hepatocyte growth factor (HGF) during human HF-dWAT co-culture, for which the c-Met receptor is expressed in the hair matrix and dermal papilla. These effects were abrogated by an HGF-neutralising antibody, and reproduced using recombinant HGF. Laser capture microdissection-based microarray analysis of the hair matrix showed that dWAT-derived HGF up-regulated KRT27, KRT73, KRT75, KRT84, KRT86 and TCHH. Mechanistically, HGF stimulated Wnt/β-catenin activity in the HM by inhibiting SFRP1 in the dermal papilla, up-regulating matrix AXIN2, LEF1, WNT6 and WNT10B expression. Our study demonstrates that dWAT regulates human hair growth and pigmentation via HGF secretion, and thus identifies important, molecular and cellular targets for therapeutic intervention in disorders of human hair growth and pigmentation.
  • Neuroendocrinology and neurobiology of sebaceous glands

    Clayton, R.W.; Langan, E.A.; Ansell, David M.; de Vos, I.J.H.M.; Göbel, K.; Schneider, M.R.; Picardo, M.; Lim, X.; van Steensel, M.A.M.; Paus, R. (2020-06)
    The nervous system communicates with peripheral tissues through nerve fibres and the systemic release of hypothalamic and pituitary neurohormones. Communication between the nervous system and the largest human organ, skin, has traditionally received little attention. In particular, the neuro-regulation of sebaceous glands (SGs), a major skin appendage, is rarely considered. Yet, it is clear that the SG is under stringent pituitary control, and forms a fascinating, clinically relevant peripheral target organ in which to study the neuroendocrine and neural regulation of epithelia. Sebum, the major secretory product of the SG, is composed of a complex mixture of lipids resulting from the holocrine secretion of specialised epithelial cells (sebocytes). It is indicative of a role of the neuroendocrine system in SG function that excess circulating levels of growth hormone, thyroxine or prolactin result in increased sebum production (seborrhoea). Conversely, growth hormone deficiency, hypothyroidism, and adrenal insufficiency result in reduced sebum production and dry skin. Furthermore, the androgen sensitivity of SGs appears to be under neuroendocrine control, as hypophysectomy (removal of the pituitary) renders SGs largely insensitive to stimulation by testosterone, which is crucial for maintaining SG homeostasis. However, several neurohormones, such as adrenocorticotropic hormone and α-melanocyte-stimulating hormone, can stimulate sebum production independently of either the testes or the adrenal glands, further underscoring the importance of neuroendocrine control in SG biology. Moreover, sebocytes synthesise several neurohormones and express their receptors, suggestive of the presence of neuro-autocrine mechanisms of sebocyte modulation. Aside from the neuroendocrine system, it is conceivable that secretion of neuropeptides and neurotransmitters from cutaneous nerve endings may also act on sebocytes or their progenitors, given that the skin is richly innervated. However, to date, the neural controls of SG development and function remain poorly investigated and incompletely understood. Botulinum toxin-mediated or facial paresis-associated reduction of human sebum secretion suggests that cutaneous nerve-derived substances modulate lipid and inflammatory cytokine synthesis by sebocytes, possibly implicating the nervous system in acne pathogenesis. Additionally, evidence suggests that cutaneous denervation in mice alters the expression of key regulators of SG homeostasis. In this review, we examine the current evidence regarding neuroendocrine and neurobiological regulation of human SG function in physiology and pathology. We further call attention to this line of research as an instructive model for probing and therapeutically manipulating the mechanistic links between the nervous system and mammalian skin.
  • Effects of criterion bias on perimetric sensitivity and response variability in glaucoma

    Rubinstein, N.J.; Turpin, A.; Denniss, Jonathan; McKendrick, A.M. (2021-01)
    The purpose of this study was to isolate and quantify the effects of observer response criterion on perimetric sensitivity, response variability, and maximum response probability. Twelve people with glaucoma were tested at three locations in the visual field (age = 47-77 years, mean deviation = -0.61 to -14.54 dB, test location Humphrey field analyzer [HFA] sensitivities = 1 to 30 dB). Frequency of seeing (FoS) curves were measured using a method of constant stimuli with two response paradigms: a "yes-no" paradigm similar to static automated perimetry and a criterion-free two interval forced choice (2IFC) paradigm. Comparison measures of sensitivity, maximum response probability, and response variability were derived from the fitted FoS curves. Sensitivity differences between the tasks varied widely (range = -11.3 dB to 21.6 dB) and did not correlate with visual field sensitivity nor whether the visual field location was in an area of steep sensitivity gradient within the visual field. Due to the wide variation in differences between the methods, there was no significant difference in mean sensitivity between the 2IFC task relative to the yes-no task, but a trend for higher sensitivity (mean = 1.9 dB, SD = 6.0 dB, P = 0.11). Response variability and maximum response probability did not differ between the tasks (P > 0.99 and 0.95, respectively). Perimetric sensitivity estimates are demonstrably altered by observer response criterion but the effect varies widely and unpredictably, even within a single test. Response bias should be considered a factor in perimetric test variability and when comparing sensitivities to nonperimetric data. The effect of response criterion on perimetric response variability varies widely and unpredictably, even within a single test.
  • Identifying cohorts using isotope mass spectrometry: the potential of temporal resolution and dietary profiles

    Beaumont, Julia; Bekvalac, J.; Harris, Sam; Batt, Catherine M. (2021)
    Archaeological skeletal material from most sites represents a cross-sectional, opportunistic sample of the burials. These are influenced by the proportion and area of the site which is excavated, the taphonomic conditions and survival of tissues. This may not be representative of the population, and in an attritional cemetery may represent a long period of use, during which humans will have differing life-courses. Here we describe a commingled skeletal assemblage, the only human remains recovered from the historically significant medieval site of St Stephen’s Chapel, Palace of Westminster, London. Using carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of bulk bone collagen and incremental dentine to investigate dietary life histories from 5 individuals, we combine the evidence with radiocarbon dating to assign them to two different temporal cohorts.
  • Hepatocyte-specific deletion of TIPARP, a negative regulator of the aryl hydrocarbon receptor, is sufficient to increase sensitivity to dioxin-induced wasting syndrome

    Hutin, D.; Tamblyn, L.; Gomez, A.; Grimaldi, Giulia; Soedling, H.; Cho, T.; Ahmed, S.; Lucas, C.; Kanduri, C.; Grant, D.M.; et al. (2018-10)
    The aryl hydrocarbon receptor (AHR) mediates the toxic effects of dioxin (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin; TCDD), which includes thymic atrophy, steatohepatitis, and a lethal wasting syndrome in laboratory rodents. Although the mechanisms of dioxin toxicity remain unknown, AHR signaling in hepatocytes is necessary for dioxin-induced liver toxicity. We previously reported that loss of TCDD-inducible poly(adenosine diphosphate [ADP]-ribose) polymerase (TIPARP/PARP7/ARTD14), an AHR target gene and mono-ADP-ribosyltransferase, increases the sensitivity of mice to dioxin-induced toxicities. To test the hypothesis that TIPARP is a negative regulator of AHR signaling in hepatocytes, we generated Tiparpfl/fl mice in which exon 3 of Tiparp is flanked by loxP sites, followed by Cre-lox technology to create hepatocyte-specific (Tiparpfl/flCreAlb) and whole-body (Tiparpfl/flCreCMV; TiparpEx3−/−) Tiparp null mice. Tiparpfl/flCreAlb and TiparpEx3−/− mice given a single injection of 10 μg/kg dioxin did not survive beyond days 7 and 9, respectively, while all Tiparp+/+ mice survived the 30-day treatment. Dioxin-exposed Tiparpfl/flCreAlb and TiparpEx3−/− mice had increased steatohepatitis and hepatotoxicity as indicated by greater staining of neutral lipids and serum alanine aminotransferase activity than similarly treated wild-type mice. Tiparpfl/flCreAlb and TiparpEx3−/− mice exhibited augmented AHR signaling, denoted by increased dioxin-induced gene expression. Metabolomic studies revealed alterations in lipid and amino acid metabolism in liver extracts from Tiparpfl/flCreAlb mice compared with wild-type mice. Taken together, these data illustrate that TIPARP is an important negative regulator of AHR activity, and that its specific loss in hepatocytes is sufficient to increase sensitivity to dioxin-induced steatohepatitis and lethality.
  • The aryl hydrocarbon receptor regulates the expression of TIPARP and its cis long non-coding RNA, TIPARP-AS1

    Grimaldi, Giulia; Rajendra, S.; Matthews, J. (2018-01)
    The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor and member of the basic helix-loop-helix-PAS family. AHR is activated by numerous dietary and endogenous compounds that contribute to its regulation of genes in diverse signaling pathways including xenobiotic metabolism, vascular development, immune responses and cell cycle control. However, it is most widely studied for its role in mediating 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity. The AHR target gene and mono-ADP-ribosyltransferase, TCDD-inducible poly-ADP-ribose polymerase (TIPARP), was recently shown to be part of a novel negative feedback loop regulating AHR activity through mono-ADP-ribosylation. However, the molecular characterization of how AHR regulates TIPARP remains elusive. Here we show that activated AHR is recruited to the TIPARP promoter, through its binding to two genomic regions that each contain multiple AHR response elements (AHREs), AHR regulates the expression of both TIPARP but also TIPARP-AS1, a long non-coding RNA (lncRNA) which lies upstream of TIPARP exon 1 and is expressed in the opposite orientation. Reporter gene and deletion studies showed that the distal AHRE cluster predominantly regulated TIPARP expression while the proximal cluster regulated TIPARP-AS1. Moreover, time course and promoter activity assays suggest that TIPARP and TIPARP-AS1 work in concert to regulate AHR signaling. Collectively, these data show an added level of complexity in the AHR signaling cascade which involves lncRNAs, whose functions remain poorly understood.
  • Methods to study TCDD-inducible poly-ADP-ribose polymerase (TIPARP) mono-ADP-ribosyltransferase activity

    Hutin, D.; Grimaldi, Giulia; Matthews, J. (2018)
    TCDD-inducible poly-ADP-ribose polymerase (TIPARP; also known as PARP7 and ARTD14) is a mono-ADP- ribosyltransferase that has emerged as an important regulator of innate immunity, stem cell pluripotency, and transcription factor regulation. Characterizing TIPARP’s catalytic activity and identifying its target proteins are critical to understanding its cellular function. Here we describe methods that we use to characterize TIPARP catalytic activity and its mono-ADP-ribosylation of its target proteins.

View more