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Dysfunctional stem and progenitor cells impair fracture healing with age

World journal of Stem Cells 2019年第6期11卷 281-296页

作者： Diane R Wagner Sonali Karnik Zachary j Gunderson jeffery j Nielsen Alanna Fennimore hunter j.promer jonathan W Lowery M Terry Loghmani Philip S Low Todd O McKinley Melissa A Kacena Matthias Clauss jiliang Li Department of Mechanical and Energy Engineering Indiana University-Purdue University IndianapolisIndianapolisIN 46202United States Department of Orthopaedic Surgery Indiana University School of MedicineIndianapolisIN 46202United States Department of Medicinal Chemistry and Molecular Pharmacology Purdue UniversityWest LafayetteIN 47907United States Department of Physical Therapy Indiana University- Purdue University IndianapolisIndianapolisIN 46202United States Division of Biomedical Science Marian University College of Osteopathic MedicineIndianapolisIN 46222United States Department of Chemistry Purdue UniversityWest LafayetteIN 47907 United States Richard L. Roudebush VA Medical Center IndianapolisIN 46202United States Department of Medicine Indiana University School of MedicineIndianapolisIN 46202United States Department of Biology Indiana University-Purdue University IndianapolisIndianapolisIN 46202United States

Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature;mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging;a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly.

关键词： Fracture healing Aging Bone Angiogenesis Mesenchymal stem cells Endothelial progenitor cells

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Design of two-dimensional carbon-nitride structures by tuning the nitrogen concentration

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npj Computational Materials 2020年第1期6卷 562-569页

作者： Saiyu Bu Nan Yao Michelle A.hunter Debra j.Searles Qinghong Yuan State Key Laboratory of Precision Spectroscopy School of Physics and Electronic ScienceEast China Normal University3663 N.Zhongshan RoadShanghai 200062PR China Centre for Theoretical and Computational Molecular Science Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQLD 4072Australia College of Teacher Education East China Normal University3663 N.Zhongshan RoadShanghai 200062PR China School of Chemistry and Molecular Biosciences The University of QueenslandBrisbaneQLD 4072Australia

Nitrogen-doped graphene(NG)has attracted increasing attention because its properties are significantly different to pristine graphene,making it useful for various applications in physics,chemistry,biology,and materials ***,the NGs that can currently be fabricated using most experimental methods always have low N concentrations and a mixture of N dopants,which limits the desirable physical and chemical properties.

关键词： dimensional carbon structures

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Hyperresolution information and hyperresolution ignorance in modelling the hydrology of the land surface

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Science China Earth Sciences 2015年第1期58卷 25-35页

作者： Keith BEVEN Hannah CLOKE Florian PAPPENBERGER Rob LAMB Neil hunter Lancaster Environment Centre Lancaster UniversityLancaster LA1 4YQUK and Department of Earth SciencesUppsala UniversityUppsalaSweden Department of Geography and Environmental Science Department of MeteorologyUniversity of ReadingReadingUK European Centre for Medium-range Weather Forecasts ReadingUK School of Geographical Sciences University of BristolBristolUK College of Hydrology and Water Resources Hehai University jBA Trust South BarnBroughton HallSkipton BD23 3AEUK jBA Consulting South BarnBroughton HallSkipton BD23 3AEUK

There is a strong drive towards hyperresolution earth system models in order to resolve finer scales of motion in the *** problem of obtaining more realistic representation of terrestrial fluxes of heat and water,however,is not just a problem of moving to hyperresolution grid *** is much more a question of a lack of knowledge about the parameterisation of processes at whatever grid scale is being used for a wider modelling *** grid scales cannot alone solve the problem of this hyperresolution *** paper discusses these issues in more detail with specific reference to land surface parameterisations and flood inundation *** importance of making local hyperresolution model predictions available for evaluation by local stakeholders is *** is expected that this will be a major driving force for improving model performance in the future.

关键词： hyperresolution models epistemic uncertainties models of everywhere communicating uncertainty flood risk

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Frankenstein

Frankenstein

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作者： Mary Shelley edited by j. Paul hunter.

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Mind the “Gap”: A Comparison of the Weekly Training Loads of English Premier League Academy Soccer Players in Under 23, Under 18 and Under 16 Age-Groups

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journal of Science in Sport and Exercise 2023年第1期5卷 34-43页

作者： jonathan M.Taylor jonathan L.Madden Frances hunter Ben j.Thorne Shaun j.McLaren School of Health and Life Sciences Teesside UniversityMiddlesbroughUK Leeds United Football Club LeedsUK Middlesbrough Football Club MiddlesbroughUK Hintsa Performance LondonUK Department of Sport and Exercise Sciences Durham UniversityDurhamUK

Purpose The transition into full-time training represents a key period in the development of young soccer *** we compared the weekly training loads(matches,field-,and resistance-training)of English Premier-League Academy soccer players from under-16(U16),under-18(U18)and under-23(U23)age-groups during a training *** Forty players(U16 n=13,U18 n=15 and U23 n=12)were monitored using global navigation satellite systems and differential ratings of perceived exertion(dRPE).External load metrics were total distance,high-speed running distance,[absolute:≥19.8 km/h,relative:≥87%of 30-15 final-velocity(vIFT)],sprint distance(absolute:≥25.2 km/h,relative:≥80%maximal sprint speed),and dynamic stress *** load metrics were dRPE training *** Other than relative sprint distance,overall weekly external training loads were substantially greater for U18s and U23s when compared with U16s[effect size range:1.09-1.99(moderate to large);±90%confidence limits~0.45].When compared with U16s,overall internal loads were substantially greater for U18s[0.69-0.95(moderate);±~0.40],but not *** in weekly training loads between U18s and U23s were *** Substantial differences in training loads between elite U16 players and their older counterparts,indicates the need for planned increases in training loads in anticipation of the transition into full-time training.

关键词： Team-sports RPE LTAD Individualised training Training load

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GroESL protects superoxide dismutase (SOD)— Deficient cells against oxidative stress and is a chaperone for SOD

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Health 2013年第10期5卷 1719-1729页

作者： Gary j. hunter Thérèse hunter Department of Physiology and Biochemistry University of Malta Msida MSD 2080 Malta Department of Physiology and Biochemistry University of Malta Msida MSD 2080 Malta

Superoxide dismutase (SOD)-deficient Escherichia coli OX326Acells are protected against chemically-induced oxidative stress by expression of the chaperonin GroESL. This protection is equivalent to expression of superoxide dismutase even though GroESL has no inherent SOD activity. Co-overexpression of GroESL and SOD in the same cells results in higher protein yields of SOD and greater metallation of SOD when compared with expression of SOD alone. Greater metallation results in the higher specific activity of SOD that is observed in heat shock, and is not due to increased synthesis of SOD mRNA or protein.

关键词： Superoxide Dismutase Chaperone Heat Shock Oxidative Stress

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Transient thermal response of micro-thermal conductivity detector (μTCD) for the identification of gas mixtures:An ultra-fast and low power method

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Microsystems & Nanoengineering 2015年第1期1卷 52-58页

作者： Alireza Mahdavifar Milad Navaei Peter j.Hesketh Melvin Findlay joseph R.Stetter Gary W.hunter School of Mechanical Engineering Georgia Institute of TechnologyAtlantaGA 30332USA KWj Engineering Inc. NewarkCA 94560USA NASA Glenn Research Center ClevelandOH 44135USA

Micro-thermal conductivity detector(μTCD)gas sensors work by detecting changes in the thermal conductivity of the surrounding medium and are used as detectors in many applications such as gas chromatography *** TCDs use steady-state resistance(i.e.,temperature)measurements of a *** this work,we developed a new measurement method and hardware configuration based on the processing of the transient response of a low thermal mass TCD to an electric current *** method was implemented for a 100-μm-long and 1-μm-thick micro-fabricated bridge that consisted of doped polysilicon conductive film passivated with a 200-nm silicon nitride *** resistance variations of theμTCD in response to a square current pulse were studied in multiple mixtures of dilute gases in *** and experimental results are presented and compared for the time resolved and steady-state regime of the sensor *** analysis and simulation show that the sensor response is exponential in the transient state,that the time constant of this exponential variation was a linear function of the thermal conductivity of the gas ambient,and that the sensor was able to quantify the mixture *** level of detection in nitrogen was estimated to be from 25 ppm for helium to 178 ppm for carbon *** this novel approach,the sensor requires approximately 3.6 nj for a single measurement and needs only 300μs of sampling *** is less than the energy and time required for steady-state DC measurements.

关键词： gas sensor MEMS micro-bridge micro-heater μTCD thermal conductivity sensor transient heat transfer modeling

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Collagen scaffolds functionalized with triple-helical peptides support 3D HUVEC culture

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Regenerative Biomaterials 2020年第5期7卷 471-482页

作者： jean-Daniel Malcor Emma j.hunter Natalia Davidenko Daniel V.Bax Ruth Cameron Serena Best Sanjay Sinha Richard W.Farndale Department of Biochemistry University of CambridgeCambridge CB21QWUK Department of Materials Science and Metallurgy University of CambridgeCambridge CB30FSUK Division of Medicine and Wellcome Trust Medical Research Council Cambridge Stem Cell InstituteUniversity of CambridgeCambridge CB20AWUK Present address:CambCol Laboratories Ltd Oak Lane Business ParkLittleportElyCambridgeshireCB79RPUK

Porous biomaterials which provide a structural and biological support for cells have immense potential in tissue engineering and cell-based therapies for tissue *** biomaterials that can host endothelial cells represent promising tools for the vascularization of engineered ***-dimensional collagen scaffolds possessing controlled architecture and mechanical stiffness are obtained through freeze–drying of collagen suspensions,followed by chemical cross-linking which maintains their ***,cross-linking scaffolds renders their biological activity suboptimal for many cell types,including human umbilical vein endothelial cells(HUVECs),by inhibiting cell–collagen ***,we have improved crucial HUVEC interactions with such cross-linked collagen biomaterials by covalently coupling combinations of triple-helical peptides(THPs).These are ligands for collagen-binding cell-surface receptors(integrins or discoidin domain receptors)or secreted proteins(SPARC and von Willebrand factor).THPs enhanced HUVEC adhesion,spreading and proliferation on 2D collagen *** grafted to 3D-cross-linked collagen scaffolds promoted cell survival over seven *** study demonstrates that THP-functionalized collagen scaffolds are promising candidates for hosting endothelial cells with potential for the production of vascularized engineered tissues in regenerative medicine applications.

关键词： collagen biomaterial endothelial cells 3D cell scaffold collagen-mimetic peptides

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Intracranial pressure is elevated at 24h post-stroke inmice

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Neuroprotection 2024年第1期2卷 60-64页

作者： Kirby E.Warren Rebecca j.Hood Fredrick R.Walker Neil j.Spratt School of Biomedical Sciences and Pharmacy University of NewcastleCallaghanAustralia hunter Medical Research Institute NewLambton HeightsAustralia School of Biomedicine Discipline of Anatomy and PathologyFaculty of Health and Medical SciencesThe University of AdelaideAdelaideAustralia Department of Neurology John Hunter HospitalNewLambton HeightsAustralia

Background:It has long been assumed that post-stroke intracranial pressure(ICP)elevation occurs because of large infarct and edema ***,we have repeatedly shown IcP elevation at 24 h post-stroke in the presence of little to no edema in *** processes are often conserved across species and types of ***,we aimed to determine if an ICP rise occurs at 24 h post-stroke in the presence of small infarct and edema volumes in ***:Mice were randomized by random number table to either photothrombotic stroke or sham surgery(n=15).Epidural ICP was recorded using a fiber optic catheter at 1 h post-stroke(baseline)and between 23 and ***:ICP was significantly higher at 24 h compared to baseline in stroke animals(n=6;10.71±6.45mmHg vs.3.74±2.20mmHg,respec-tively;p=0.03).ICP at 24 h was also significantly higher in stroke mice compared to sham(n=6;3.45±1.43mmHg;p=0.02).There was no change in ICP in sham mice(p=0.9).Edema volumes in stroke animals were small(0.04±0.04 mm3)and unlikely to have caused significant ICP ***:This study provides evidence of an edema-independent ICP elevation following small ischemic stroke in *** occurrence of this rise supports our findings in other species and suggests it is caused by a previously undescribed mechanism.

关键词： cerebraledema intracranial pressure ischemic stroke

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Meta-Study of Particulate Detection Losses on Radioactive Air Sample Filters

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journal of Environmental Protection 2022年第8期13卷 589-602页

作者： j. Matthew Barnett hunter Z. Edwards Pacific Northwest National Laboratory Richland USA

Several mathematical relationships between air sample filter mass loading and the correlated analytical self-absorption factor were developed using data from other published research in this meta-study. Gross-alpha and -beta applications are addressed for this research. As filter media becomes loaded with particulate matter, there is potential for measurement losses due to self-absorption by mass loading. Components contributing to absorption include particulate dust, radioactive particulates, and filter material. Standards indicate a correction factor should be used when the penetration of radioactive material into the collection media or self-absorption of radiation by the material collected would reduce the detection rate by more than 5%. Previously, losses due to self-absorption have been reported up to 100% over a range up to ~10 mg⋅cm-2 mass loading. These absorption losses then can be used to determine a correction factor for sample results. For low mass loadings (e.g., ≤0.1 mg⋅cm-2) corrections factors in the 0.85 - 1 range have been recommended and used, while at higher mass loadings nearer to 10 mg⋅cm-2 correction factors closer to 0 (representing near 100% losses) are used. Based on data from published studies, the different methods for relating percent loss due to self-absorption to mass loading include linear, exponential, quadratic, and trinomial derived functions. Where applicable, both forced zero and non-forced zero results were evaluated. From the derived functions evaluated, the trinomial function provided the best fit. Once the sample filter mass loading is known, the trinomial function can be applied to estimate losses and the corresponding self-absorption factor. When applied to routine operating conditions for radiological facility stacks monitored at the Pacific Northwest National Laboratory for an average sample filter mass loading of 0.09 ± 0.12 (2σ) mg⋅cm-2 (excluding negative values and outliers

关键词： Air Sampling Environmental Radioactivity Self-Absorption Correction Factor Standards

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