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Adjusting the physico-chemical properties of collagen scaffolds to accommodate primary osteoblasts and endothelial cells

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Regenerative Biomaterials 2023年第1期10卷 590-602页

作者： Nima meyer Daniel V.Bax Jochen Beck Ruth E.cameron Serena m.Best Department of materials Science and metallurgy University of CambridgeCambridge CB30FSUK Geistlich Pharma AG Product DevelopmentWolhusenSwitzerland

Collagen-based biomaterials are used widely as tissue engineering scaffolds because of their excellent bioactivity and their similarity to the natural *** regeneration of healthy bone tissue requires simultaneous support for both osteoblasts and,where angiogenesis is intended,endothelial *** it is important to tailor carefully the biochemical and structural characteristics of the scaffold to suit the needs of each cell *** work describes for the first time a systematic study to gain insight into the cell type-specific response of primary human osteoblast(hOBs)and human dermal microvascular endothelial cells(HDmECs)to insoluble collagen-based *** behaviour was evaluated on both 2D films and 3D scaffolds,produced using *** collagen was cross-linked at various EDC/NHS concentrations and mono-cultured with hOBs and HDmECs to assess the effect of architectural features and scaffold stabilization on cell *** was observed that 3D scaffolds cross-linked at 30%of the standard conditions in literature offered an optimal combination of mechanical stiffness and cellular response for both cell types,although endothelial cells were more sensitive to the degree of cross-linking than *** features have a time-dependent impact on the cell migration profile,with alignment being the most influential parameter overall.

关键词： angiogenesis collagen scaffolds cell migration EDC/NHS cross-linking

Ischemic cholangiopathy after livertransplantation

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Hepatobiliary & Pancreatic Diseases International 2005年第4期4卷 495-501页

作者： Andrew m. cameron Ronald W. Busuttil Division of Liver and Pancreas Transplantation Department of SurgeryDavid Geffen School of Medicine at UCLALos AngelesCalifornia 90095-7054USA

Orthotopic liver transplantation ( OLT) has evolved over the last forty years from an experimental endeavor to standard of care therapy for many patients with end stage hepatic disease. many technical advances have contributed to the current success of OLT, but surgical complications, especially involving the biliary reconstruction, remain a morbid problem. Biliary complications after OLT include leaks and strictures. Strictures may be anastoinotic or intrahepatic and diffuse, as seen in cases of hepatic artery thrombosis. Current efforts to expand the limited donor pool include the use of non-heart beating donors. The organ procurement process in these donors entails an increased period of warm ischemia and results with non-heart beating donor grafts have been mixed. It is now appreciated that there is an increased incidence of subsequent diffuse biliary stricturing or ' ischemic cholangiopathy' in recipients of these organs. Animal models of this phenomenon and potential therapeutic strategies targeted at ischemic cholangiopathy are being developed with potential applicability to non-heart beating donation and will be the focus of this review.

关键词： orthotopic liver transplantation biliary strictures non-anastoinotic strictures ischemic cholangiopathy non-heart beating donor

Duplicate publication bias weakens the validity of metaanalysis of immunosuppression after transplantation

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World Journal of Gastroenterology 2017年第39期23卷 7198-7200页

作者： cameron J Fairfield Ewen m Harrison Stephen J Wigmore Department of Clinical Surgery University of Edinburgh Royal Infirmary of Edinburgh

Duplicate publication can introduce significant bias into a meta-analysis if studies are inadvertently included more than once. many studies are published in more than one journal to maximize readership and impact of the study findings. Inclusion of multiple publications of the same study within a meta-analysis affords inappropriate weight to the duplicated data if reports of the same study are not linked together. As studies which have positive findings are more likely to be published in multiple journals this leads to a potential overestimate of the benefits of an intervention. Recent advances in immunosuppression strategies following liver transplantation have led to many studies investigating immunosuppressive regimes including immunosuppression monotherapy. In this letter we focus on a recently published meta-analysis by Lan et al investigating studies assessing immunosuppression monotherapy for liver transplantation. The authors claim to have identified fourteen separate randomised studies investigating immunosuppression monotherapy. Seven of the references appear to relate to only three studies which have been subject to duplicate publication. Several similarities can be identified in each of the duplicate publications including similar authorship, identical immunosuppression regimes, identical dates of enrolment and citation of the original publication in the subsequent manuscripts. We discuss the evidence of the duplicate publication inclusion in the meta-analysis.

关键词： Liver transplantation Immunosuppression meta-analysis Duplicate publication Bias

Neurotransmitter systems in mouse airways

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中国药理学与毒理学杂志 2017年第10期31卷 1015-1016页

作者： Peter W ABEL cameron m KIEFFER Ya-ping TU Department of Pharmacology Creighton University School of Medicine

OBJECTIVE The objective of this study was to characterize the neurotransmitter systems that cause constriction of murine *** murine precision cut lung slices(PCLS)and trachea were prepared,placed into perfusion chambers equipped with platinum electrodes and stimulated transmurally(1.0 ms,50 V,0.1-30 Hz).To measure PCLS constriction,changes in airway luminal area in response to electric field stimulation(EFS)were captured as video images quantified using Image J *** trachea,changes in isometric tension were recorded using Grass force *** response curves were generated in the absence and the presence of the inhibitors magnesium,atropine and capsaicin and responses analyzed and compared using a student's t-test(Pmanner that was best fit by a biphasic ***-specific stimulation was verified by mg^(2+) *** airway constriction to 30 Hz EFS in PCLS was(51.8±3.0)%while tracheal constriction averaged(551±80)***,in PCLS the muscarinic receptor antagonist atropine(10μmol·L^(-1))blocked(99.5±7.2)%of EFS induced constriction at 1 Hz,but only blocked(23.3±3.8)%of EFS induced constriction at 30 Hz and eliminated the first phase but not the second phase of the biphasic EFS *** with capsaicin to deplete sensory neurotransmitters significantly increased EFS constriction supporting the presence of sensory neurotransmitter systems in *** These data are consistent with parasympathetic constriction of airways by acetylcholine at lower EFS frequencies while higher frequencies release sensory dilator *** data provide evidence for multiple nerve types innervating airways which may provide novel targets for treatment of lung disease.

关键词： airways nerve stimulation airway constriction atropine capsaicin

Divergence and constraint in the thermal sensitivity of aquatic insect swimming performance

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Current Zoology 2020年第5期66卷 555-564页

作者： Alisha A.SHAH Eva m.S.Bacmeister Juan G.Rubalcaba cameron K.Ghalambor Department of Biology Colorado State UniversityFort CollinsCO80526USA Division of Biological Sciences University of MontanaMissoulaMT59812USA Department of Biology McGill University1205 Docteur PenfieldMontrealQCCanada Department of Biology Centre for Biodiversity DynamicsNorwegian University of Science and Technology(NTNU)TrondheimNorway

Environmental temperature variation may play a significant role in the adaptive evolutionary divergence of ectotherm thermal performance curves(TPCs).However,divergence in TPCs may also be constrained due to various ***,we measured TPCs for swimming velocity of temperate and tropical mayflies(Family:Baetidae)and their stonefly predators(Family:Perlidae)from different *** predicted that differences in seasonal climatic regimes would drive divergence in TPCs between temperate and tropical *** tropical temperatures should favor the evolution of"specialists"that perform well across a narrow range of ***,variable temperatures in temperate zones,however,should favor"generalists"that perform well across a broad range of *** phylogenetically paired comparisons of mayflies and stoneflies,swimming speed was generally unaffected by experimental temperature and did not differ among populations between latitudes,suggesting a maintenance of performance breadth across elevation and *** exception was found between temperate and tropical mayflies at low elevation where climatic differences between latitudes are *** addition,TPCs did not differ between mayflies and their stonefly predators,except at tropical low *** results indicate that divergence in TPCs may be con strai ned in aquatic in sects except under the most differe nt ther・mal regimes,perhaps because of trade-offs that reduce thermal sensitivity and increase performance breadth.

关键词： aquatic insects climate variability elevation latitude predator-prey swimming performance thermal performance curve

Vitamin D receptor expression in human bone tissue and dose-dependent activation in resorbing osteoclasts

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Bone Research 2016年第3期4卷 164-173页

作者： Allahdad Zarei Alireza morovat Kassim Javaid cameron P Brown Botnar Research Centre Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Science University of Oxford Oxford UK Clinical Biochemistry Oxford University Hospitals NHS Trust Oxford UK

The effects of vitamin D on osteoblast mineralization are well documented. Reports of the effects of vitamin D on osteoclasts, however, are conflicting, showing both inhibition and stimulation. Finding that resorbing osteoclasts in human bone express vitamin D receptor （VDR）, we examined their response to different concentrations of 25-hydroxy vitamin D3 [25（OH）D3] （100 or 500 nmol·L^-1） and 1,25-dihydroxy vitamin D3 [1,25（OH）2D3] （0.1 or 0.5 nmol·L^-1） metabolites in cell cultures. Specifically, CD14＋ monocytes were cultured in charcoal-stripped serum in the presence of receptor activator of nuclear factor kappa-B ligand （RANKL） and macrophage colony-stimulating factor （m-CSF）. Tartrate-resistant acid phosphatase （TRAP） histochemical staining assays and dentine resorption analysis were used to identify the size and number of osteoclast cells, number of nuclei per cell and resorption activity. The expression of VDR was detected in human bone tissue （ex vivo） by immunohistochemistry and in vitro cell cultures by western blotting. Quantitative reverse transcription-PCR （qRT-PCR） was used to determine the level of expression of vitamin D-related genes in response to vitamin D metabolites. VDR-related genes during osteoclastogenesis, shown by qRT-PCR, was stimulated in response to 500 nmol·L^-1 of 25（OH）D3 and 0.1-0.5 nmol·L^-1 of 1,25（OH）2D3, upregulating cytochrome P450 family 27 subfamily B member I （CYP27B1） and cytochrome P450 family 24 subfamily A member I （CYP24A1）. Osteoclast fusion transcripts transmembrane 7 subfamily member 4 （tm7sf4） and nuclear factor of activated T-cell cytoplasmic 1 （nfatcl） where downregulated in response to vitamin D metabolites. Osteoclast number and resorption activity were also increased. Both 25（OH）D3 and 1,25（OH）2D3 reduced osteoclast size and number when co-treated with RANKL and m-CSF. The evidence for VDR expression in resorbing osteoclasts in vivo and low-dose effects of 1,25（OH）2D3 on osteoclasts in vitro may therefore provide

关键词： Vitamin D receptor expression in human bone tissue and dose-dependent activation in resorbing osteoclasts bone

Summer monsoon and dust signals recorded in the Dasuopu firn core, central Himalayas

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Chinese Science Bulletin 1999年第21期44卷 2010-2015页

作者： cameron P.Wake Paul A.mayewski Climate Change Research Center Institute for the Study of EarthOcean and Space(EOS)University of New Hampshire DurhamNH 03824USAClimate Change Research CenterInstitute for the Study of EarthOcean and Space(EOS)University of New Hampshire DurhamNH 03824USA

In September 1997, a 15-m firn core was recovered from an elevation of 7 000 m a. s.l. from the Dasuopu Glacier in the central Himalayas. The analysis of δ18O values and major ion (Ca2+ , mg2+ , NH4+ , SO2- and NO3-) concentrations shows that average annual accumulation is 0.75 m (water equivalent) in the Dasuopu firn core. The seasonal variations of δ18O values and major ion concentrations in the core indicate that present summer monsoon and

关键词： firn core records of summer monsoon and dust signals central Himalayas.

Atomically dispersed dual-metal-site PGm-free electrocatalysts for oxygen reduction reaction:Opportunities and challenges

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Susmat 2022年第5期2卷 569-590页

作者： Xiaoxuan Yang cameron Priest Yang Hou Gang Wu College of Chemical and Biological Engineering Zhejiang UniversityHangzhouChina Department of Chemical and Biological Engineering University at BuffaloThe State University of New YorkBuffaloNew YorkUSA Institute of Zhejiang University-Quzhou QuzhouChina School of Biological and Chemical Engineering NingboTech UniversityNingboChina

Atomically dispersed and nitrogen coordinated single metal site(mNx,m=Fe,Co,or mn)moieties embedded in partially graphitized carbon(denoted as m–N–C)are recognized as the most promising platinum group metal-free catalysts for the oxygen reduction reaction(ORR)in proton exchange membrane fuel ***,simply regulating their coordination environments and local structures of single metal sites cannot fundamentally change active site structure,which leads to insufficient activity and stability.A second transition metal can be incorporated to design dual-metal sites,offering a new opportunity to modulate the electronic and geometric structures of m–N–C ***,exploring optimal atomically dispersed dual-metal-site is essential to designing new active sites with enhanced ORR activity,and stability,especially breaking the activity-stability *** review provides a comprehensive analysis of the advances in developing atomically dispersed dual-metal site catalysts for the ORR,including innovative synthesis methods,primary structural configurations,and the mechanisms to promote catalytic *** aim to elucidate the crucial structure–property correlation,emphasizing the inherent electronic and geometric effects of dual metal ***,we discuss the current challenges of dual-metal site catalysts concerning rational design,precise synthesis,and high-fidelity structural characterization.

关键词： dual metal sites electrocatalysis fuel cells oxygen reduction PGm-free catalyst

Targeted protein delivery:carbodiimide crosslinking influences protein release from microparticles incorporated within collagen scaffolds

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Regenerative Biomaterials 2019年第5期6卷 279-287页

作者： Constantin Edi Tanase Omar Qutachi Lisa J.White Kevin m.Shakesheff Andrew W.mcCaskie Serena m.Best Ruth E.cameron Department of materials Science and metallurgy University of CambridgeCambridge Centre for Medical MaterialsCambridge27Charles Babbage RoadCB30FSUK Centre for Biomolecular Sciences School of PharmacyUniversity of NottinghamUniversity ParkNottingham NG72RDUK Division of Trauma&Orthopaedic Surgery Department of SurgeryUniversity of CambridgeBox 180Addenbrooke’s HospitalHills RoadCambridge CB20QQUK Present address:School of Pharmacy De Montforte UniversityLeicester LE19BHUK

Tissue engineering response may be tailored via controlled,sustained release of active agents from protein-loaded degradable microparticles incorporated directly within three-dimensional(3D)ice-templated collagen ***,the effects of covalent crosslinking during scaffold preparation on the availability and release of protein from the incorporated microparticles have not been ***,we load 3D ice-templated collagen scaffolds with controlled additions of poly-(DL-lactide-co-glycolide)*** probe the effects of subsequent N-(3-dimethylaminopropyl)-N0-ethylcarbodiimide hydrochloride crosslinking on protein release,using microparticles with different internal protein *** isothiocyanate labelled bovine serum albumin is used as a model protein *** scaffolds display a homogeneous microparticle distribution,and a reduction in pore size and percolation diameter with increased microparticle addition,although these values did not fall below those reported as necessary for cell *** protein distribution within the microparticles,near the surface or more deeply located within the microparticles,was important in determining the release profile and effect of crosslinking,as the surface was affected by the carbodiimide crosslinking reaction applied to the *** of microparticles with a high proportion of protein at the surface caused both a reduction and delay in protein *** located within the bulk of the microparticles,was protected from the crosslinking reaction and no delay in the overall release profile was seen.

关键词： collagen scaffolds PLGA microparticles FITC-BSA EDC crosslinking pore size percolation diameter