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Current progress in use of adipose derived stem cells in peripheral nerve regeneration

World Journal of Stem Cells 2015年第1期7卷 51-64页

作者： Shomari DL Zack-Williams peter e butler Deepak M Kalaskar Centre for Nanotechnology and Regenerative Medicine Division of Surgery and Interventional Science University College London WC1E 6BT London United Kingdom Department of Plastic and Reconstructive Surgery Royal Free Hampstead NHS Trust Hospital NW3 2QG London United Kingdom

Unlike central nervous system neurons; those in the peripheral nervous system have the potential for full regeneration after injury. Following injury, recovery is controlled by schwann cells which replicate and modulate the subsequent immune response. The level of nerve recovery is strongly linked to the severity of the initial injury despite the significant advancements in imaging and surgical techniques. Multiple experimental model shave been used with varying successes to augment the natural regenerative processes which occur following nerve injury. Stem cell therapy in peripheral nerve injury may be an important future intervention to improve the best attainable clinical results. In particular adipose derived stem cells(ADSCs) are multipotent mesenchymal stem cells similar to bone marrow derived stem cells, which are thought to have neurotrophic properties and the ability to differentiate into multiple lineages. They are ubiquitous within adipose tissue; they can form many structures resembling the mature adult peripheral nervous system. Following early in vitro work; multiple small and large animal in vivo models have been used in conjunction with conduits, autografts and allografts to successfully bridge the peripheral nerve gap. Some of the ADSC related neuroprotective and regenerative properties have been elucidated however much work remains before a model can be used successfully in human peripheral nerve injury(PNI). This review aims to provide a detailed overview of progress made in the use of ADSC in PNI, with discussion on the role of a tissue engineered approach for PNI repair.

关键词： Peripheral nerve injury Adipose derivedstem cells Cell based therapies Stem cells

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Control of stem cell fate by engineering their micro and nanoenvironment

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World Journal of Stem Cells 2015年第1期7卷 37-50页

作者： Michelle F Griffin peter e butler Alexander M Seifalian Deepak M Kalaskar UCL Division of Surgery and Interventional Science Centre for Nanotechnology and Regenerative Medicine University College London London NW3 2PF United Kingdom Department of Plastic and Reconstructive Surgery Royal Free Hampstead NHS Trust Hospital London NW3 2PF United Kingdom

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(eCM) in vivo have shown to regulate stem cell differentiation. The delivery of eCM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.

关键词： Biomaterials Scaffold Stem cells Surfacetopography Tissue engineering

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面部移植一种修复重度面部损伤的新方法

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英国医学杂志中文版 2006年第2期9卷 73-74页

作者： peter e M butler Alex Clarke Shehan Hettiaratchy 晏晓青 consultant plastic surgeon Department of Plastic Surgery Royal Free HospitalLondon NW3 2QG consultant psychologist Department of Plastic Surgery Royal Free Hospital London NW3 2QG specialist registrar Department of Plastic Surgery Queen Victoria Hospital East Grinstead RH19 3DZ

世界上第一例面部移植手术已经由法国报道了，但是判断它是否是整形再造外科一个新领域开始的标志，还要根据其临床结果而定。长期以来，面部移植手术一直被认为是技术上的挑战，但它在临床上是可行的。。对面部重度畸形的患者来说，这... 详细信息

世界上第一例面部移植手术已经由法国报道了，但是判断它是否是整形再造外科一个新领域开始的标志，还要根据其临床结果而定。长期以来，面部移植手术一直被认为是技术上的挑战，但它在临床上是可行的。。对面部重度畸形的患者来说，这项手术的优点是对其功能、美容和心理均有所改善，而缺点是要求长期应用免疫抑制剂，所以争论的关键在于该手术是否利大于弊。

关键词：面部移植手术面部损伤重度畸形新方修复临床结果免疫抑制剂长期应用利大于弊

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Drag reduction behavior of hydrolyzed polyacrylamide/xanthan gum mixed polymer solutions

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Petroleum Science 2017年第2期14卷 412-423页

作者： Mehdi Habibpour peter e. Clark School of Chemical engineering Oklahoma State University Stillwater OK 74078 USA

Partially hydrolyzed polyacrylamide（HPAM）as the main component of slickwater fracturing fluid is a shear-sensitive polymer,which suffers from mechanical degradation at turbulent flow *** different concentrations of HPAM as well as mixtures of polyacrylamide/xanthan gum were prepared to investigate the possibility of improving shear stability of *** reduction（DR）measurements were performed in a closed flow *** HPAM solutions,the extent of DR increased from 30%to67%with increasing HPAM concentration from 100 to1000 *** the HPAM solutions suffered from mechanical degradation and loss of DR efficiency over the shearing *** indicated that the resistance to shear degradation increased with increasing polymer *** efficiency of 600 wppm xanthan gum（XG）was 38%,indicating that XG was not as good a drag reducer as *** with only 6%DR decline,XG solution exhibited a better shear stability compared to HPAM *** HPAM/XG solutions initially exhibited greater DR（40%and 55%）compared to XG,but due to shear degradation,DR%dropped for HPAM/XG *** to 200 wppm HPAM solution,addition of XG did not improve the drag reduction efficiency of HPAM/XG mixed solutions though XG slightly improved the resistance against mechanical degradation in HPAM/XG mixed polymer solutions.

关键词： Slickwater Polyacrylamide Xanthan gum Drag reduction Shear stability

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Polymer-virus core-shell structures prepared via co-assembly and template synthesis methods

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Science China Chemistry 2010年第1期53卷 71-77页

作者： SUTHIWANGCHAROeN Nisaraporn PReVeLIGe peter e.Jr Department of Chemistry and Biochemistry and Nanocenter University of South CarolinaColumbiaSouth Carolina 29208USA Department of Microbiology University of Alabama at BirminghamBirminghamAL 35294USA

Bionanoparticles(BNPs),consisting of virus and virus-like assemblies,have attracted much attention in the biomedical field for their applications such as imaging and targeted drug delivery,owing to their well-defined structures and well-controlled ***-based core-shell structures provide a unique system for the investigation of biological interactions such as protein-protein and protein-carbohydrate ***,it is still a challenge to prepare the BNPs-based core-shell ***,we describe(i) co-assembly method and(ii) template synthesis method in the development of polymer-BNPs core-shell *** two methods can be divided into three different *** system A,different polymers including poly(2-vinylpyridine)(P2VP),poly(4-vinylpyridine)(P4VP) and poly(ε-caprolactone)-block-poly(2-vinylpyridine)(PCL-b-P2VP) can form a raspberry-like structure with *** system B,polystyrene(PS) spheres end capped with free amine and BNPs can form a core-shell *** System C,layer-by-layer(LBL) method is used to prepare positive charged PS particles,which can be used as a template to form the core-shell structures with *** two methods may open a new way for preparing novel protein-based functional materials for potential applications in the biomedical field.

关键词： core-shell structures bionanoparticles virus polymers co-assembly template synthesis layer-by-layer

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Making Sense of Hospital Project MisPerformance: Over Budget, Late, Time and Time Again—Why? And What Can Be Done About It?

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engineering 2022年第5期8卷 183-201页

作者： peter e.D.Love Lavagnon A.Ika School of Civil and Mechanical engineering Curtin UniversityPerthWA 6845Australia Telfer School of Management University of OttawaOttawaON KIN 6N5Canada

Hospital projects worldwide often experience misperformance,showing a tendency to exceed their estimated cost,miss their deadline,suffer quality problems,and yield benefit *** this ubiquitous problem,this paper aims to make sense of this phenomenon by addressing the following research question:How can we make sense of hospital project misperformance,and what can be done to mitigate its occurrence?We use an illustrative case study approach and the analytical lens of sense-making to examine the misperformance of three mega-hospital *** research reveals issues such as scope changes,an inability to adapt and respond to risk and uncertainty,ineffectual project management and governance,and optimism bias,which combine to impact project performance *** suggest that the two prominent theoretical perspectives dominating the literature in this field fall short of adequately explaining hospital project *** provide suggestions for improving the procurement process of hospitals and submit there is a need to develop a robust and balanced theory of project misperformance.

关键词： Cost Hospital Optimism bias Procurement Project management Performance Sense-making

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How does male-male competition generate negative frequency-dependent selection and disruptive selection during speciation？

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Current Zoology 2018年第1期64卷 89-99页

作者： peter D. DIJKSTRA Shana e. BORDeR Department of Biology Central Michigan University Mount Pleasant MI 48859 USA

Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male-male competition in speciation is relatively understudied. Here, we outline how male-male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection （advantage of rare phenotype arising from stronger male-male competition between similar male phenotypes compared with dissimilar male pheno- types） and disruptive selection （advantage of extreme phenotypes） drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male-male competition interacts with other life-history functions and that variable male com- petitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on compet- itor signals. We call for a better integration of male-male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mecha- nisms. Altogether, we present a more comprehensive framework for studying the role of male-male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions.

关键词： disruptive selection life-history trade-offs male-male competition negative frequency-dependent selection speciation

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Neural Network-Based Second Order Reliability Method(NNBSORM)for Laminated Composite Plates in Free Vibration

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Computer Modeling in engineering & Sciences 2018年第4期115卷 105-129页

作者： Mena e.Tawfik peter L.Bishay edward e.Sadek Aerospace engineering Department Faculty of EngineeringCairo UniversityEgypt Mechanical and Aerospace engineering Department Rutgersthe State University of New JerseyNew BrunswickNJUSA Mechanical engineering Department College of Engineering and Computer ScienceCalifornia State UniversityNorthridgeCAUSA.

Monte Carlo Simulations(MCS),commonly used for reliability analysis,require a large amount of data points to obtain acceptable accuracy,even if the Subset Simulation with Importance Sampling(SS/IS)methods are *** Second Order Reliability Method(SORM)has proved to be an excellent rapid tool in the stochastic analysis of laminated composite structures,when compared to the slower MCS ***,SORM requires differentiating the performance function with respect to each of the random variables involved in the *** most suitable approach to do this is to use a symbolic solver,which renders the simulations very slow,although still faster than ***,the inability to obtain the derivative of the performance function with respect to some parameters,such as ply thickness,limits the capabilities of the classical *** this work,a Neural Network-Based Second Order Reliability Method(NNBSORM)is developed to replace the finite element algorithm in the stochastic analysis of laminated composite plates in free *** of the ability to obtain expressions for the first and second derivatives of the NN system outputs with respect to any of its inputs,such as material properties,ply thicknesses and orientation angles,the need for using a symbolic solver to calculate the derivatives of the performance function no longer *** proposed approach is accordingly much faster,and easily allows for the consideration of ply thickness *** present analysis showed that dealing with ply thicknesses as random variables results in 37%increase in the laminate’s probability of failure.

关键词： Reliability analysis artificial neural network composite laminates subset simulation importance sampling Monte Carlo

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Deletion or underexpression of the Y-chromosome genes CDY2 and HSFY is associated with maturation arrest in American men with nonobstructive azoospermia

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Asian Journal of Andrology 2012年第5期14卷 676-682页

作者： peter J Stahl Anna N Mielnik Christopher e Barbieri peter N Schlegel Darius A Paduch Department of Urology Weill Cornell Medical CollegeNew York Presbyterian HospitaI-CornellNew YorkNY 10065USA

Maturation arrest （MA） refers to failure of germ cell development leading to clinical nonobstructive azoospermia. Although the azoospermic factor （AZF） region of the human Y chromosome is clearly implicated in some cases, thus far very little is known about which individual Y-chromosome genes are important for complete male germ cell development. We sought to identify single genes on the Y chromosome that may be implicated in the pathogenesis of nonobstructive azoospermia associated with MA in the American population. Genotype-phenotype analysis of 132 men with Y-chromosome microdeletions was performed. Protein-coding genes associated with MA were identified by visual analysis of a genotype-phenotype map. Genes associated with MA were selected as those genes within a segment of the Y chromosome that, when completely or partially deleted, were always associated with MA and absence of retrievable testicular sperm. expression of each identified gene transcript was then measured with quantitative RT-PCR in testicular tissue from separate cohorts of patients with idiopathic MA and obstructive azoospermia. Ten candidate genes for association with MA were identified within an 8.4-Mb segment of the Y chromosome overlapping the AZFb region. CDY2and HSFYwere the only identified genes for which differences in expression were observed between the MA and obstructive azoospermia cohorts. Men with obstructive azoospermia had 12-fold higher relative expression of CDY2transcript （1.33__.0.40 vs. 0.11＋_0.04; P=O.O003） and 16-fold higher expression of HSFYtranscript （0.78__.0.32 vs. 0.05_0.02; P=O.O005） compared to men with MA. CDY2 and HSFYwere also underexpressed in patients with Sertoli cell only syndrome. These data indicate that CDY2and HSFYare located within a segment of the Y chromosome that is important for sperm maturation, and are underexpressed in testicular tissue derived from men with MA. These observations suggest that impairments in CDY2 or HSFYexpression could be impli

关键词： CDY1 protein CDY2 protein genetics histology HSFY human make infertility nonobstructive azoospermia spermato-genesis sperm maturation

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Claudin-11 and occludin are major contributors to Sertoli cell tight junction function, in vitro

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Asian Journal of Andrology 2016年第4期18卷 620-626页

作者： Mark J McCabe Caroline FH Foo Marcel e Dinger peter M Smooker peter G Stanton Male Fertility Regulation Laboratory Hudson Institute of Medical Research Monash Medical Centre Clayton Victoria 3168 Australia School of Applied Sciences Royal Melbourne Institute of Technology University Bundoora Victoria 3088 Australia Kinghorn Centre for Clinical Genomics Garvan Institute of Medical Research Darlinghurst New South Wales 2010 Australia St Vincent's Clinical School UNSW Sydney New South Wales 2052 Australia.

The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.

关键词： blood-testis barrier claudin-11 occludin Sertoli cell tight junction siRNA

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