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result(s) for
"Mitchell, Geoffrey"
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Biomaterials for In Situ Tissue Regeneration: A Review
by
Mitchell, Geoffrey
,
Abdulghani, Saba
in
biomaterials
,
in situ tissue engineering
,
natural polymers
2019
This review focuses on a somewhat unexplored strand of regenerative medicine, that is in situ tissue engineering. In this approach manufactured scaffolds are implanted in the injured region for regeneration within the patient. The scaffold is designed to attract cells to the required volume of regeneration to subsequently proliferate, differentiate, and as a consequence develop tissue within the scaffold which in time will degrade leaving just the regenerated tissue. This review highlights the wealth of information available from studies of ex-situ tissue engineering about the selection of materials for scaffolds. It is clear that there are great opportunities for the use of additive manufacturing to prepare complex personalized scaffolds and we speculate that by building on this knowledge and technology, the development of in situ tissue engineering could rapidly increase. Ex-situ tissue engineering is handicapped by the need to develop the tissue in a bioreactor where the conditions, however optimized, may not be optimum for accelerated growth and maintenance of the cell function. We identify that in both methodologies the prospect of tissue regeneration has created much promise but delivered little outside the scope of laboratory-based experiments. We propose that the design of the scaffolds and the materials selected remain at the heart of developments in this field and there is a clear need for predictive modelling which can be used in the design and optimization of materials and scaffolds.
Journal Article
Rapidly increasing end-of-life care needs: a timely warning
2017
Current trends in population ageing show that, in the near future, while more people will live longer, more will also die at any one time. Health systems, as well as individual practitioners, are only just becoming aware of the extent of this problem. Health systems will have to rapidly change practice to manage the number of people dying in the coming years, many with complex multimorbid conditions. The changes involved should include a personal recognition by all health professionals of their role in caring for the dying, and healthcare education must include end-of-life care management as part of the core curriculum. Further, health systems must improve integration between primary care and specialist clinicians to ensure the burden is shared efficiently across the system. Finally, it should be recognised that end-of-life care is not terminal care, but should be anticipated months or sometimes years ahead through advance care planning for known future complications by the patient’s clinical team, as well as by patients and their main carers, to manage crises as they ariserather than react to them once they arise.
Please see related article: https://bmcmedicine.biomedcentral.com/articles/
10.1186/s12916-017-0860-2
.
Journal Article
Barriers for conducting clinical trials in developing countries- a systematic review
by
Alemayehu, Chalachew
,
Mitchell, Geoffrey
,
Nikles, Jane
in
Analysis
,
Attitude to Health
,
Barriers
2018
Background
Clinical trials for identification of efficient and effective new diagnostic and treatment modalities are needed to address disproportionately high burden of communicable (e.g., HIV/AIDS, tuberculosis, and malaria) and non-communicable diseases (e.g., diabetes) in developing countries. However, gross under-representation in global clinical trial platforms contributes to sustained health inequity in these countries. We reviewed the literature on barriers facing clinical researchers in developing countries for conducting clinical trials in their countries.
Methods
Literature indexed in PubMed, Embase, CINAHL and Web of Science, WHO Global Health Library were searched. Grey literature was also searched. Search key words included barriers, challenges, clinical trials and developing countries. Articles within the scope of this review were appraised by two reviewers.
Results
Ten studies, which are reported in 15 papers, were included in this review. Following critical review we identified five unifying themes for barriers. Barriers for conducting clinical trials included lack of financial and human capacity, ethical and regulatory system obstacles, lack of research environment, operational barriers and competing demands.
Conclusion and recommendation
There were substantial barriers at system, organization and individual level. We propose that to address this problem, instituting a system for wider implementation of local investigator-initiated trials is warranted. These trials are more applicable to local populations because they build on local healthcare knowledge. They are more demand-led, influence policy and responsive to a country’s needs because they are driven by a local or national agenda.
Journal Article
Bioactive Electrospun Fibers of Poly(ε-Caprolactone) Incorporating α-Tocopherol for Food Packaging Applications
by
Vasile, Cornelia
,
Stoleru, Elena
,
Mitchell, Geoffrey R.
in
alpha-Tocopherol - chemistry
,
alpha-Tocopherol - pharmacology
,
Antioxidants
2021
Antioxidant activity is an important feature for food contact materials such as packaging, aiming to preserve freshness and retard food spoilage. Common bioactive agents are highly susceptible to various forms of degradation; therefore, protection is required to maintain functionality and bioavailability. Poly(ε-caprolactone) (PCL), a biodegradable GRAS labeled polymer, was used in this study for encapsulation of α-tocopherol antioxidant, a major component of vitamin E, in the form of electrospun fibers. Rheological properties of the fiber forming solutions, which determine the electrospinning behavior, were correlated with the properties of electrospun fibers, e.g., morphology and surface properties. Interactions through hydrogen bonds were evidenced between the two components. These have strong effect on structuration of macromolecular chains, especially at low α-tocopherol amounts, decreasing viscosity and elastic modulus. Intra-molecular interactions in PCL strengthen at high α-tocopherol amounts due to decreased solvation, allowing good structural recovery after cease of mechanical stress. Morphologically homogeneous electrospun fibers were obtained, with ~6 μm average diameter. The obtained fibers were highly hydrophobic, with fast release in 95% ethanol as alternative simulant for fatty foods. This induced good in vitro antioxidant activity and significant in vivo reduction of microbial growth on cheese, as determined by respirometry. Therefore, the electrospun fibers from PCL entrapping α-tocopherol as bioactive agent showed potential use in food packaging materials.
Journal Article
The Use of Scattering Data in the Study of the Molecular Organisation of Polymers in the Non-Crystalline State
by
Gkourmpis, Thomas
,
Mitchell, Geoffrey R.
in
Coupling (molecular)
,
Crystal structure
,
Crystallinity
2020
Scattering data for polymers in the non-crystalline state, i.e., the glassy state or the molten state, may appear to contain little information. In this work, we review recent developments in the use of scattering data to evaluate in a quantitative manner the molecular organization of such polymer systems. The focus is on the local structure of chain segments, on the details of the chain conformation and on the imprint the inherent chemical connectivity has on this structure. We show the value of tightly coupling the scattering data to atomistic-level computer models. We show how quantitative information about the details of the chain conformation can be obtained directly using a model built from definitions of relatively few parameters. We show how scattering data may be supplemented with data from specific deuteration sites and used to obtain information hidden in the data. Finally, we show how we can exploit the reverse Monte Carlo approach to use the data to drive the convergence of the scattering calculated from a 3d atomistic-level model with the experimental data. We highlight the importance of the quality of the scattering data and the value in using broad Q scattering data obtained using neutrons. We illustrate these various methods with results drawn from a diverse range of polymers.
Journal Article
Crosslinked Nanocomposite Sodium Alginate-Based Membranes with Titanium Dioxide for the Dehydration of Isopropanol by Pervaporation
by
Premakshi, H.G.
,
Mitchell, Geoffrey R.
,
Kariduraganavar, Mahadevappa Y.
in
2-Propanol - chemistry
,
Alginates - chemistry
,
Cross-Linking Reagents - chemistry
2020
Sodium alginate (NaAlg) based membranes were prepared using a solution technique, crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-MA). Subsequently, the membranes were modified by the incorporation of 0, 10, 20, 30 and 40% w/w of titanium dioxide with respect to sodium alginate. The membranes thus obtained were designated as M, M-1, M-2, M-3 and M-4, respectively. An equilibrium swelling experiment was performed using different compositions of the water and isopropanol mixtures. Subsequently, we used a pervaporation cell fitted with each membrane in order to evaluate the extent of the pervaporation dehydration of isopropanol. Among the membranes studied, the membranes containing 40 mass% of titanium dioxide exhibited the highest separation factor(α) of 24,092, with a flux(J) of 18.61 × 10−2 kg/m2∙h at 30 °C for 10 mass% w/w of water in the feed. The total flux and the flux of water were found to overlap with each other, indicating that these membranes can be effectively used to break the azeotropic point of water–isopropanol mixtures. The results clearly indicate that these nanocomposite membranes exhibit an excellent performance in the dehydration of isopropanol. The activation energy values obtained for the water permeation were significantly lower than those of the isopropanol permeation, underlining that these membranes have a high separation ability for the water–isopropanol system. The estimated activation energies for total permeation (EP) and total diffusion (ED) values ranged between 10.60 kJ∙mol−1 and 3.96 kJ∙mol−1, and 10.76 kJ∙mol−1 and 4.29 kJ∙mol−1, respectively. The negative change in the enthalpy values for all the membranes indicates that sorption was mainly dominated by Langmuir’s mode of sorption.
Journal Article
Attention-deficit/hyperactivity disorder: are we helping or harming?
by
Thomas, Rae
,
Mitchell, Geoffrey K
,
Batstra, Laura
in
Attention Deficit Disorder with Hyperactivity - diagnosis
,
Attention Deficit Disorder with Hyperactivity - epidemiology
,
Attention Deficit Disorder with Hyperactivity - therapy
2013
Journal Article
The expanding role of primary care in cancer control
by
Gupta, Sumit
,
Neal, Richard D
,
Earle, Craig
in
Cancer
,
Delivery of Health Care - methods
,
Diabetes
2015
The nature of cancer control is changing, with an increasing emphasis, fuelled by public and political demand, on prevention, early diagnosis, and patient experience during and after treatment. At the same time, primary care is increasingly promoted, by governments and health funders worldwide, as the preferred setting for most health care for reasons of increasing need, to stabilise health-care costs, and to accommodate patient preference for care close to home. It is timely, then, to consider how this expanding role for primary care can work for cancer control, which has long been dominated by highly technical interventions centred on treatment, and in which the contribution of primary care has been largely perceived as marginal. In this Commission, expert opinion from primary care and public health professionals with academic and clinical cancer expertise—from epidemiologists, psychologists, policy makers, and cancer specialists—has contributed to a detailed consideration of the evidence for cancer control provided in primary care and community care settings. Ranging from primary prevention to end-of-life care, the scope for new models of care is explored, and the actions needed to effect change are outlined. The strengths of primary care—its continuous, coordinated, and comprehensive care for individuals and families—are particularly evident in prevention and diagnosis, in shared follow-up and survivorship care, and in end-of-life care. A strong theme of integration of care runs throughout, and its elements (clinical, vertical, and functional) and the tools needed for integrated working are described in detail. All of this change, as it evolves, will need to be underpinned by new research and by continuing and shared multiprofessional development.
Journal Article
Development of novel 3D scaffolds using BioExtruder by varying the content of hydroxyapatite and silica in PCL matrix for bone tissue engineering
by
Pattanashetti, Nandini A.
,
Mitchell, Geoffrey R.
,
Alves, Nuno
in
Biodegradability
,
Biomedical materials
,
Bones
2020
Polycaprolactone (PCL) is considered as a most widely used biodegradable polymers in tissue engineering. But, PCL is also associated with certain limitations like, low stiffness, hydrophobic nature and limited cell affinity. These drawbacks are addressed in the present study by incorporating different wt% of silicon dioxide (SiO
2
) and hydroxyapatite (HAp) in the PCL matrix. 3D scaffolds were developed using a novel BioExtruder. The physicochemical properties, thermal stability and wettability of the composite scaffolds were studied systematically. Optical and Scanning Electron Microscopic images were analysed for morphological evaluation of the scaffolds. The pore size of the developed scaffolds increased from 290 to 315 μm with increasing SiO
2
content, as examined by scanning electron microscope. An improved compressive modulus of 68.82 MPa was observed for 15 wt% SiO
2
incorporated composite scaffold. The in-vitro degradation study of the composite scaffolds demonstrated an increase in the degradation rate for PCL/HAp scaffolds, while no significant change was observed for SiO
2
incorporated scaffolds. Further, the cytotoxicity and cell proliferation studies were carried out using L929 Mouse Fibroblasts and MG-63 Osteoblasts respectively. The developed scaffolds revealed no toxic effects towards the cellular response and an increase in cell proliferation of ≥90% was observed during 7 days of cell culture. Thus, the scaffolds were proved to be potential candidate for bone tissue engineering application, particularly the scaffold with 10 wt% SiO
2
incorporation into PCL/HAp (75/15) composite has resulted into higher cell proliferative % and improved mechanical strength.
Journal Article
Exit from quiescence displays a memory of cell growth and division
2017
Reactivating quiescent cells to proliferate is critical to tissue repair and homoeostasis. Quiescence exit is highly noisy even for genetically identical cells under the same environmental conditions. Deregulation of quiescence exit is associated with many diseases, but cellular mechanisms underlying the noisy process of exiting quiescence are poorly understood. Here we show that the heterogeneity of quiescence exit reflects a memory of preceding cell growth at quiescence induction and immediate division history before quiescence entry, and that such a memory is reflected in cell size at a coarse scale. The deterministic memory effects of preceding cell cycle, coupled with the stochastic dynamics of an Rb-E2F bistable switch, jointly and quantitatively explain quiescence-exit heterogeneity. As such, quiescence can be defined as a distinct state outside of the cell cycle while displaying a sequential cell order reflecting preceding cell growth and division variations.
The quiescence-exit process is noisy even in genetically identical cells under the same environmental conditions. Here the authors show that the heterogeneity of quiescence exit reflects a memory of preceding cell growth at quiescence induction and immediate division history prior to quiescence entry.
Journal Article