• Tunable Supramolecular Hydrogels for Selection of Lineage-Guiding Metabolites in Stem Cell Cultures

      Alakpa, E.V.; Jayawarna, V.; Lampel, A.; Burgess, K.V.; West, C.C.; Bakker, S.C.J.; Roy, S.; Javid, Nadeem; Fleming, S.; Lamprou, D.A.; et al. (2016-08-11)
      Stem cells are known to differentiate in response to the chemical and mechanical properties of the substrates on which they are cultured. Thus, supramolecular biomaterials with tunable properties are well suited for the study of stem cell differentiation. In this report, we exploited this phenomenon by combining stem cell differentiation in hydrogels with variable stiffness and metabolomics analysis to identify specific bioactive lipids that are uniquely used up during differentiation. To achieve this, we cultured perivascular stem cells on supramolecular peptide gels of different stiffness, and metabolite depletion followed. On soft (1 kPa), stiff (13 kPa), and rigid (32 kPa) gels, we observed neuronal, chondrogenic, and osteogenic differentiation, respectively, showing that these stem cells undergo stiffness-directed fate selection. By analyzing concentration variances of >600 metabolites during differentiation on the stiff and rigid gels (and focusing on chondrogenesis and osteogenesis as regenerative targets, respectively), we identified that specific lipids (lysophosphatidic acid and cholesterol sulfate, respectively), were significantly depleted. We propose that these metabolites are therefore involved in the differentiation process. In order to unequivocally demonstrate that the lipid metabolites that we identified play key roles in driving differentiation, we subsequently demonstrated that these individual lipids can, when fed to standard stem cell cultures, induce differentiation toward chondrocyte and osteoblast phenotypes. Our concept exploits the design of supramolecular biomaterials as a strategy for discovering cell-directing bioactive metabolites of therapeutic relevance.
    • Tuning proton behavior in a ternary molecular complex.

      Thomas, L.H.; Blagden, Nicholas; Gutmann, M.J.; Kallay, A.A.; Parkin, A.; Seaton, Colin C.; Wilson, C.C. (2010-06)
      The multicomponent ternary complex of 4-dimethylaminobenzoic acid (4-DABA), 3,5-dinitrobenzoic acid (3,5-DNBA), and 4,40-bipyridine (BIPY) has been studied by variable temperature X-ray and neutron diffraction. Proton disorder is observed within the 4-DABA homodimers present and quantitatively evaluated from neutron data. The effect of the crystal environment and in particular the pyramidalization of the nitrogen atom within the 4-DABA molecule and the consequential effect on the presence of hydrogen atom disorder are discussed with reference to the previously determined pure 4-DABA structure and the binary cocrystal with 3,5-DNBA.
    • Tuning the aggregation behavior of pH-responsive micelles by copolymerization

      Wright, D.B.; Patterson, J.P.; Pitto-Barry, Anaïs; Cotenda, P.; Chassenieux, C.; Colombani, O.; O'Reilly, R.K. (2015-04-14)
      Amphiphilic diblock copolymers, poly(2-(diethylamino)ethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate), P(DEAEMA-co-DMAEMA)-b-PDMAEMA with various amounts of DEAEMA have been synthesized by RAFT polymerization. Their micellization in water has been investigated by scattering measurements over a wide pH range. It appeared that the polymers self-assembled into pH sensitive star like micelles. For a given composition, when the pH is varied the extent of aggregation can be tuned reversibly by orders of magnitude. By varying the copolymer composition in the hydrophobic block, the onset and extent of aggregation were shifted with respect to pH. This class of diblock copolymer offers the possibility to select the range of stimuli-responsiveness that is useful for a given application, which can rarely be achieved with conventional diblock copolymers consisting of homopolymeric blocks.
    • Two Heterometallic Ionic Compounds with Isolated [3d] and [4f] Complex Units: Field-Induced Single-Ion Magnet (SIM) Behavior Observed from a Mononuclear Dysprosium(III) Complex

      Nayak, Sanjit; Novitchi, G.; Holynska, M.; Dehnen, S. (2014-09)
      This article corrects http://onlinelibrary.wiley.com/enhanced/doi/10.1002/ejic.201402114. 2014(19): 3065-3071.
    • Two Heterometallic Ionic Compounds with Isolated [3d] and [4f] Complex Units: Field-Induced Single-Ion Magnet (SIM) Behavior Observed from a Mononuclear Dysprosium(III) Complex

      Nayak, Sanjit; Novitchi, G.; Holynska, M.; Dehnen, S. (2014-07)
      Two new complexes, [Fe3(μ3-O)(inicH)6(H2O)3][Gd(NO3)6]·(NO3)4·nH2O (1) and [Fe3(μ3-O)(inicH)6(H2O)3][Dy(NO3)5 (H2O)]·(NO3)5·n(H2O) (2) with two isolated complex moieties, were generated when isonicotinic acid was treated with iron(III) nitrate and the corresponding lanthanide(III) nitrate in water. The structures were determined by single-crystal X-ray diffraction studies. In these compounds, the anionic lanthanide complexes are encapsulated by trinuclear [Fe3(μ3-O)(inicH)6(H2O)3]7+ cationic cluster units, which is facilitated by hydrogen-bonding interactions. Investigation of the magnetic properties reveals that 2 shows slow relaxation of magnetization at low magnetic field (Hdc = 1.0 kOe), with an energy barrier of 23 K originating from a single [Dy(NO3)5(H2O)]2– anion.
    • Two plasmid-encoded genes of enteropathogenic Escherichia coli strain K798 promote invasion and survival within HEp-2 cells

      Burska, Urszula L.; Fletcher, Jonathan N. (2014)
      Enteropathogenic Escherichia coli (EPEC) are considered to be extracellular pathogens, inducing attaching and effacing lesions following their attachment to the surface of eukaryotic cells; however, in vitro and in vivo invasion by EPEC has been reported in several studies. A cloned 4.6 kb fragment of EPEC plasmid pLV501 has been shown to facilitate invasion of E. coli K-12, and here we further investigate the nature of this process. Two of the three complete open reading frames contained within the plasmid fragment have been cloned to E. coli, and in HEp-2 adherence assays both tniA2 and pecM were shown to be expressed during the first 3 h of infection from a plac promoter. Escherichia coli transformants carrying pecM alone or in combination with tniA2 were able to both survive intracellularly and escape eukaryotic cells to re-establish themselves within the medium, whereas those bacterial cells carrying tniA2 alone could not be isolated from within HEp-2 cells after 24 h of infection, but were present in the previously sterile medium surrounding the cells. Bacteria carrying pecM and tniA2 adhered to HEp-2 cells with sites of adhesion characterized by underlying actin polymerization. The invasive potential conferred by these genes may give EPEC strains a survival advantage during prolonged infection.
    • Two-way effects of surfactants on Pickering emulsions stabilized by the self-assembled microcrystals of alpha-cyclodextrin and oil

      Li, X.; Li, H.; Xiao, Q.; Wang, L.; Wang, M.; Lu, X.; York, Peter; Shi, S.; Zhang, J. (2014)
      The influence of surfactants on the stability of cyclodextrin (CD) Pickering emulsions is not well understood. In this study, we report two-way effects of Tween 80 and soybean lecithin (PL) on the long term stability of Pickering emulsions stabilized by the self-assembled microcrystals of alpha-CD and medium chain triglycerides (MCT). The CD emulsions in the absence and presence of Tween 80 or PL at different concentrations were prepared and characterized by the droplet size, viscosity, contact angle, interfacial tension and residual emulsion values. After adding Tween 80 and PL, similar effects on the size distribution and contact angle were observed. However, changes of viscosity and interfacial tension were significantly different and two-way effects on the stability were found: (i) synergistic enhancement by Tween 80; (ii) inhibition at low and enhancement at high concentrations by PL. The stability enhancement of Tween 80 was due to the interfacial tension decrease caused by the interaction of Tween 80 with CD at the o/w interface at lower concentrations, and significant viscosity increase caused by the Tween 80-CD assembly in the continuous phase. For PL at low concentrations, the replacement of alpha-CD/MCT by alpha-CD/PL particles at the o/w interface was observed, leading to inhibitory effects. High concentrations of PL resulted in an extremely low interfacial tension and stable emulsion. In conclusion, the extensive inclusion of surfactants by CD leads to their unique effects on the stability of CD emulsions, for which the changes of viscosity and interfacial tension caused by host-guest interactions play important roles.
    • Type 2 diabetes impairs venous, but not arterial smooth muscle cell function: possible role of differential RhoA activity

      Riches-Suman, Kirsten; Warburton, P.; O'Regan, D.J.; Turner, N.A.; Porter, K.E. (2014-04)
      Background/purpose Coronary heart disease is the leading cause of morbidity in patients with type 2 diabetes mellitus (T2DM), frequently resulting in a requirement for coronary revascularization using the internal mammary artery (IMA) or saphenous vein (SV). Patency rates of SV grafts are inferior to IMA and further impaired by T2DM whilst IMA patencies appear similar in both populations. Smooth muscle cells (SMC) play a pivotal role in graft integration; we therefore examined the phenotype and proliferative function of IMA- and SV-SMC isolated from non-diabetic (ND) patients or those diagnosed with T2DM. Methods/materials SMC were cultured from fragments of SV or IMA. Morphology was analyzed under light microscopy (spread cell area measurements) and confocal microscopy (F-actin staining). Proliferation was analyzed by cell counting. Levels of RhoA mRNA, protein and activity were measured by real-time RT-PCR, western blotting and G-LISA respectively. Results IMA-SMC from T2DM and ND patients were indistinguishable in both morphology and function. By comparison, SV-SMC from T2DM patients exhibited significantly larger spread cell areas (1.5-fold increase, P < 0.05), truncated F-actin fibers and reduced proliferation (33% reduction, P < 0.05). Furthermore, lower expression and activity of RhoA were observed in SV-SMC of T2DM patients (37% reduction in expression, P < 0.05 and 43% reduction in activity, P < 0.01). Conclusions IMA-SMC appear impervious to phenotypic modulation by T2DM. In contrast, SV-SMC from T2DM patients exhibit phenotypic and functional changes accompanied by reduced RhoA activity. These aberrancies may be epigenetic in nature, compromising SMC plasticity and SV graft adaptation in T2DM patients.
    • Type-I and Type-II Core-Shell Quantum Dots: Synthesis and Characterization

      Dorfs, D.; Hickey, Stephen G.; Eychmüller, A. (2010-02)
    • UK-India Centre for Advanced Technology for Minimizing Indiscriminate Use of Antibiotics:"Exploring biology of antibiotic resistance and potential targets for early diagnosis and effective management of infectious diseases”

      Rimmer, Stephen; Garg, P.; MacNeil, S.; Shepherd, J.; Foster, S. (2017-05)
      During January 15th – 17th, 2017 a group of scientists met, under the auspices of the UK-India Centre for Advanced Technology for Minimizing Indiscriminate Use of Antibiotics, to discuss the further developments and potential solutions to antimicrobial resistance. This was the third work shop under this funding stream held in Hyderabad. The presentations and outcomes of the workshop are released here. Key out comes included the need to address improved treatment and detection of TB, delivery of antimicrobial peptides, potential strategies for combating beta-lactam resistance.
    • Ultrasmall SnO(2) nanocrystals: hot-bubbling synthesis, encapsulation in carbon layers and applications in high capacity Li-ion storage

      Ding, L.; He, S.; Miao, S.; Jorgensen, M.R.; Leubner, S.; Yan, C.; Hickey, Stephen G.; Eychmüller, A.; Xu, J.; Schmidt, O.G. (2014-04-15)
      Ultrasmall SnO2 nanocrystals as anode materials for lithium-ion batteries (LIBs) have been synthesized by bubbling an oxidizing gas into hot surfactant solutions containing Sn-oleate complexes. Annealing of the particles in N2 carbonifies the densely packed surface capping ligands resulting in carbon encapsulated SnO2 nanoparticles (SnO2/C). Carbon encapsulation can effectively buffer the volume changes during the lithiation/delithiation process. The assembled SnO2/C thus deliver extraordinarily high reversible capacity of 908 mA.h.g(-1) at 0.5 C as well as excellent cycling performance in the LIBs. This method demonstrates the great potential of SnO2/C nanoparticles for the design of high power LIBs.
    • Ultrasound-triggered therapeutic microbubbles enhance the efficacy of cytotoxic drugs by increasing circulation and tumour drug accumulation and limiting bioavailability and toxicity in normal tissues

      Ingram, N.; McVeigh, L.E.; Abou-Saleh, R.H.; Maynard, J.; Peyman, S.A.; McLaughlan, J.R.; Fairclough, M.; Marston, G.; Valleley, E.M.A.; Jimenez-Macias, J.L.; et al. (2020)
      Most cancer patients receive chemotherapy at some stage of their treatment which makes improving the efficacy of cytotoxic drugs an ongoing and important goal. Despite large numbers of potent anti-cancer agents being developed, a major obstacle to clinical translation remains the inability to deliver therapeutic doses to a tumor without causing intolerable side effects. To address this problem, there has been intense interest in nanoformulations and targeted delivery to improve cancer outcomes. The aim of this work was to demonstrate how vascular endothelial growth factor receptor 2 (VEGFR2)-targeted, ultrasound-triggered delivery with therapeutic microbubbles (thMBs) could improve the therapeutic range of cytotoxic drugs. Methods: Using a microfluidic microbubble production platform, we generated thMBs comprising VEGFR2-targeted microbubbles with attached liposomal payloads for localised ultrasound-triggered delivery of irinotecan and SN38 in mouse models of colorectal cancer. Intravenous injection into tumor-bearing mice was used to examine targeting efficiency and tumor pharmacodynamics. High-frequency ultrasound and bioluminescent imaging were used to visualise microbubbles in real-time. Tandem mass spectrometry (LC-MS/MS) was used to quantitate intratumoral drug delivery and tissue biodistribution. Finally, 89Zr PET radiotracing was used to compare biodistribution and tumor accumulation of ultrasound-triggered SN38 thMBs with VEGFR2 targeted SN38 liposomes alone. Results: ThMBs specifically bound VEGFR2 in vitro and significantly improved tumor responses to low dose irinotecan and SN38 in human colorectal cancer xenografts. An ultrasound trigger was essential to achieve the selective effects of thMBs as without it, thMBs failed to extend intratumoral drug delivery or demonstrate enhanced tumor responses. Sensitive LC-MS/MS quantification of drugs and their metabolites demonstrated that thMBs extended drug exposure in tumors but limited exposure in healthy tissues, not exposed to ultrasound, by persistent encapsulation of drug prior to elimination. 89Zr PET radiotracing showed that the percentage injected dose in tumors achieved with thMBs was twice that of VEGFR2-targeted SN38 liposomes alone. Conclusions: thMBs provide a generic platform for the targeted, ultrasound-triggered delivery of cytotoxic drugs by enhancing tumor responses to low dose drug delivery via combined effects on circulation, tumor drug accumulation and exposure and altered metabolism in normal tissues.
    • Ultraviolet-radiation induced skin inflammation: dissecting the role of bioactive lipids

      Pilkington, S.M.; Rhodes, L.E.; Nicolaou, Anna (2011)
      Acute exposure of human skin to the ultraviolet radiation (UVR) in sunlight results in the sunburn response. This is mediated in part by pro-inflammatory eicosanoids and other bioactive lipids, which are in turn produced via mechanisms including UVR-induction of oxidative stress, cell signalling and gene expression. Sunburn is a self-limiting inflammation offering a convenient and accessible system for the study of human cutaneous lipid metabolism. Recent lipidomic applications have revealed that a wider diversity of eicosanoids may be involved in the sunburn response than previously appreciated. This article reviews the effects of UVR on cutaneous lipids and examines the contribution of bioactive lipid mediators in the development of sunburn. Since human skin is an active site of polyunsaturated fatty acid (PUFA) metabolism, and these macronutrients can influence the production of eicosanoids/bioactive lipids, as well as modulate cell signalling, gene expression and oxidative stress, the application of PUFA as potential photoprotective agents is also considered.
    • Unaltered perception of suprathreshold contrast in early glaucoma despite sensitivity loss

      Bham, H.A.; Dewsbery, S.D.; Denniss, Jonathan (2020-07)
      PURPOSE. Glaucoma raises contrast detection thresholds, but our natural visual environment is dominated by high contrast that may remain suprathreshold in early to moderate glaucoma. This study investigates the effect of glaucoma on the apparent contrast of visible stimuli. METHODS. Twenty participants with glaucoma with partial visual field defects (mean age, 72 ± 7 years) and 20 age-similar healthy controls (mean age, 70 ± 7 years) took part. Contrast detection thresholds for Gabor stimuli (SD, 0.75°) of four spatial frequencies (0.5, 1.0, 2.0, and 4.0 c/deg) were first measured at 10° eccentricity, both within and outside of visual field defects for participants with glaucoma. Subsequently, the contrast of a central Gabor was matched to that of a peripheral Gabor with contrast fixed at two times or four times the detection threshold. Data were analyzed by linear mixed modelling. RESULTS. Compared with controls, detection thresholds for participants with glaucoma were raised by 0.05 ± 0.025 (Michelson units, ± SE; P = 0.12) and by 0.141 ± 0.026 (P < 0.001) outside and within visual field defects, respectively. For reference stimuli at two times the detection contrast, matched contrast ratios (matched/reference contrast) were 0.16 ± 0.039 (P < 0.001) higher outside compared with within visual field defects in participants with glaucoma. Matched contrast ratios within visual field defects were similar to controls (mean 0.033 ± 0.066 lower; P = 0.87). For reference stimuli at four times the detection contrast, matched contrast ratios were similar across all three groups (P = 0.58). Spatial frequency had a minimal effect on matched contrast ratios. CONCLUSIONS. Despite decreased contrast sensitivity, people with glaucoma perceive the contrast of visible suprathreshold stimuli similarly to healthy controls. These results suggest possible compensation for sensitivity loss in the visual system.
    • Uncovering Molecular Processes in Crystal Nucleation and Growth by Using Molecular Simulation

      Anwar, Jamshed; Zahn, D. (27/01/2011)
      Exploring nucleation processes by molecular simulation can provide a mechanistic understanding at the atomic level and also enables kinetic and thermodynamic quantities to be estimated. However, whilst the potential for modeling crystal nucleation and growth processes is immense, there are specific technical challenges to modeling [that need to be tackled]. In general, rare events, such as nucleation cannot be simulated using a direct ¿brute force¿ molecular dynamics approach. In recent years, the limited time and length scales that are accessible by conventional molecular dynamics simulations have inspired a number of advances to tackle problems that were hitherto considered outside the scope of molecular simulation. While general insights and features could be explored from efficient generic models, The newer methods have paved the way to realistic crystal nucleation scenarios. The association of single ions in solvent environments, the mechanisms of motif formation in solvents, the nucleation process itself, ripening reactions, role of additives, as well as the self-organization of nanocrystals can now all be investigated at the molecular level. The insights gained should complement experiments and enhance our fundamental understanding of the processes involved and facilitate the rational design of new materials.
    • Understanding images in biological and computer vision

      Schofield, A.J.; Gilchrist, I.D.; Bloj, Marina; Leonardis, A.; Bellotto, N. (2018-06-15)
      This issue of Interface Focus is a collection of papers arising out of a Royal Society Discussion meeting entitled ‘Understanding images in biological and computer vision’ held at Carlton Terrace on the 19th and 20th February, 2018. There is a strong tradition of inter-disciplinarity in the study of visual perception and visual cognition. Many of the great natural scientists including Newton [1], Young [2] and Maxwell (see [3]) were intrigued by the relationship between light, surfaces and perceived colour considering both physical and perceptual processes. Brewster [4] invented both the lenticular stereoscope and the binocular camera but also studied the perception of shape-from-shading. More recently, Marr's [5] description of visual perception as an information processing problem led to great advances in our understanding of both biological and computer vision: both the computer vision and biological vision communities have a Marr medal. The recent successes of deep neural networks in classifying the images that we see and the fMRI images that reveal the activity in our brains during the act of seeing are both intriguing. The links between machine vision systems and biology may at sometimes be weak but the similarity of some of the operations is nonetheless striking [6]. This two-day meeting brought together researchers from the fields of biological and computer vision, robotics, neuroscience, computer science and psychology to discuss the most recent developments in the field. The meeting was divided into four themes: vision for action, visual appearance, vision for recognition and machine learning.
    • Understanding long-term opioid prescribing for non-cancer pain in primary care: A qualitative study

      McCrorie, C.; Closs, S.J.; House, A.; Petty, Duncan R.; Ziegler, L.; Glidewell, L.; West, R.; Foy, R. (2015-09)
      Background: The place of opioids in the management of chronic, non-cancer pain is limited. Even so their use is escalating, leading to concerns that patients are prescribed strong opioids inappropriately and alternatives to medication are under-used. We aimed to understand the processes which bring about and perpetuate long-term prescribing of opioids for chronic, non-cancer pain. Methods: We held semi-structured interviews with patients and focus groups with general practitioners (GPs). Participants included 23 patients currently prescribed long-term opioids and 15 GPs from Leeds and Bradford, United Kingdom (UK). We used a grounded approach to the analysis of transcripts. Results: Patients are driven by the needs for pain relief, explanation, and improvement or maintenance of quality of life. GPs’ responses are shaped by how UK general practice is organised, available therapeutic choices and their expertise in managing chronic pain, especially when facing diagnostic uncertainty or when their own approach is at odds with the patient’s wishes. Four features of the resulting transaction between patients and doctors influence prescribing: lack of clarity of strategy, including the risk of any plans being subverted by urgent demands; lack of certainty about locus of control in decision-making, especially in relation to prescribing; continuity in the doctor-patient relationship; and mutuality and trust. Conclusions: Problematic prescribing occurs when patients experience repeated consultations that do not meet their needs and GPs feel unable to negotiate alternative approaches to treatment. Therapeutic short-termism is perpetuated by inconsistent clinical encounters and the absence of mutually-agreed formulations of underlying problems and plans of action. Apart from commissioning improved access to appropriate specialist services, general practices should also consider how they manage problematic opioid prescribing and be prepared to set boundaries with patients.
    • Understanding the economic influence of the dyeing industry in Pompeii through the application of experimental archaeology and thermodynamics

      Hopkins, Heather J.; Willimott, L.; Janaway, Robert C.; Robinson, Damian; Seale, W.J. (2005)
      The influence of the dyeing industry in Pompeii on the local economy has been under discussion since the publication by Moeller in 1976. Since no absolute answer has emerged, the question was re-examined using two additional methods, experimental archaeology and the principles of thermodynamics. A full-scale replica of a dyeing apparatus from Pompeii was constructed and used to simulate repeated dye runs, and so determine operating parameters such as the times involved to heat and cool a vat and the consumables needed. This first replica also allowed a better understanding of how the apparatus was actually used. Thermodynamic principles, which were applied to understand the successes and failures within the experimental work, suggested that the vat operated in a predictable way and enabled the operational mechanics of the vat to be established. It is now possible to use both the experimental results and the thermodynamic modelling to determine not just the consumables used, but also the working environment needed for the vat to operate, allowing an understanding of the limitations to dyeing and to workers. Issues of practicality such as storage of consumables and disposal of exhaust gases may now be thoroughly examined. 2 Eventually it will be possible to determine the operating parameters of each of the dye vats, the quantities of consumables involved and the amount that could be produced. This should help answer the question as to the significance of the dye industry in Pompeii to the local economy.
    • Understanding the neural basis of amblyopia.

      Barrett, Brendan T.; Bradley, A.; McGraw, Paul V. (2004)
      Amblyopia is the condition in which reduced visual function exists despite full optical correction and an absence of observable ocular pathology. Investigation of the underlying neurology of this condition began in earnest around 40 years ago with the pioneering studies conducted by Hubel and Wiesel. Their early work on the impact of monocular deprivation and strabismus initiated what is now a rapidly developing field of cortical plasticity research. Although the monocular deprivation paradigm originated by Hubel and Wiesel remains a key experimental manipulation in studies of cortical plasticity, somewhat ironically, the neurology underlying the human conditions of strabismus and amblyopia that motivated this early work remains elusive. In this review, the authors combine contemporary research on plasticity and development with data from human and animal investigations of amblyopic populations to assess what is known and to reexamine some of the key assumptions about human amblyopia.