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The interaction of stem cells and vascularity in peripheral nerve regeneration

Neural regeneration research 2021年第8期16卷 1510-1517页

作者： Sara Saffari Tiam M.Saffari Dietmar J.O.Ulrich steven e.r.hovius Alexander Y.Shin Division of Hand and Microvascular Surgery Department of Orthopedic SurgeryMayo ClinicRochesterMNUSA Department of Plastic and reconstructive Surgery Radboud University Medical CenterNijmegenthe Netherlands

The degree of nerve regeneration after peripheral nerve injury can be altered by the microenvironment at the site of injury. Stem cells and vascularity are postulated to be a part of a complex pathway that enhances peripheral nerve regeneration;however, their interaction remains unexplored. This review aims to summarize current knowledge on this interaction, including various mechanisms through which trophic factors are promoted by stem cells and angiogenesis. Angiogenesis after nerve injury is stimulated by hypoxia, mediated by vascular endothelial growth factor, resulting in the growth of preexisting vessels into new areas. Modulation of distinct signaling pathways in stem cells can promote angiogenesis by the secretion of various angiogenic factors. Simultaneously, the importance of stem cells in peripheral nerve regeneration relies on their ability to promote myelin formation and their capacity to be influenced by the microenvironment to differentiate into Schwann-like cells. Stem cells can be acquired through various sources that correlate to their differentiation potential, including embryonic stem cells, neural stem cells, and mesenchymal stem cells. each source of stem cells serves its particular differentiation potential and properties associated with the promotion of revascularization and nerve regeneration. exosomes are a subtype of extracellular vesicles released from cell types and play an important role in cell-to-cell communication. exosomes hold promise for future transplantation applications, as these vesicles contain fewer membrane-bound proteins, resulting in lower immunogenicity. This review presents pre-clinical and clinical studies that focus on selecting the ideal type of stem cell and optimizing stem cell delivery methods for potential translation to clinical practice. Future studies integrating stem cell-based therapies with the promotion of angiogenesis may elucidate the synergistic pathways and ultimately enhance nerve regeneration.

关键词： angiogenesis exosomes nerve graft nerve regeneration peripheral nerve injury revascularization Schwann cells stem cells stem cell delivery vascularity

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Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

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Geo-Spatial Information Science 2018年第4期21卷 288-293页

作者： steven e.Greco Department of Human ecology University of CaliforniaDavisCAUSA

Conceptually,the theory and implementation of“map projection”in geographic information system(GIS)technology is difficult to comprehend for most introductory students and novice *** this difficulty is the concept of a“map projection file”that defines map projection parameters of geo-spatial *** problem of the“missing projection file”appears ubiquitous for all users,especially in practice where data is widely *** common problem is inadvertent misapplication of the“Define Projection”tool that can result in a GIS dataset with an incorrectly defined map projection *** education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors.A novel pedagogical device is introduced in this paper:the seven possible states of GIS data with respect to map projection and *** seven possible states are:(1)a projected coordinate system(PCS)that is correctly defined,(2)a PCS that is incorrectly defined,(3)a PCS that is undefined,(4)a geographic coordinate system(GCS)that is correctly defined,(5)a GCS that is incorrectly defined,(6)a GCS that is undefined,and(7)a *** created automated troubleshooting tools to determine a missing map projection file are discussed.

关键词： GIS education map projection error map projection file define projection

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Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism

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Insect Science 2016年第5期23卷 695-703页

作者： Kathleen M Kneeland steven r. Skoda John e. Foster Department of entomology 103 Entomology Haft University of Nebraska-Lincoln Lincoln NE 68583 USDA-ArS-KBUSLIrL Screwworm research Unit 2700 Fredericksburg Road Kern/ille TX 78028 USA

The stable fly, Stomoxys calcitrans （L.）（Diptera： Muscidae）, is a blood-feeding, economically important pest of animals and humans worldwide. Improved management strategies are essential and their development would benefit from studies on genetic di- versity of stable flies. especially if done on a global scale, such research could generate information necessary for the development and application of more efficient control meth- ods. Herein we report on a genetic study of stable flies using amplified fragment length polymorphism, with samples of 10-40 individuals acquired from a total of 25 locations in the Nearctic, Neotropic, Palearctic, Afrotropic and Australasian biogeographical regions. We hypothesized that genetic differentiation would exist across geographical barriers. Although Fsx （0.33） was moderately high, the Gsx （0.05; representing genetic diversity between individuals） was very low; Nm values （representing gene flow） were high （9.36）. The mismatch distribution and tests of neutrality suggested population expansion, with no genetic differentiation between locations. The analysis of molecular variance （AMOVA） results showed the majority of genetic diversity was within groups. The mantel test showed no correlation between geographic and genetic distance; this strongly supports the AMOVA results. These results suggest that stable flies did not show genetic differentiation but are panmictic, with no evidence of isolation by distance or across geographical barriers.

关键词： AFLP biting flies external parasites genetic diversity livestock pests Stomoxys calcitrans

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Combination therapy for erectile dysfunction： an update review

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Asian Journal of Andrology 2011年第3期13卷 382-390,510,511页

作者： rohit r Dhir Hao-Cheng Lin steven e Canfield run Wang Division of Urology University of Texas Medical School at Houston Houston TX 77030 USA Department of Urology Affiliated Drum Tower Hospital Nanjing University School of Medicine Nanjing 210008 China Department of Urology University of Texas MD Anderson Cancer Center Houston TX 77030 USA

The introduction of oral phosphodiesterase-5 inhibitors （PDe51s） in the late 1990s and early 2000s revolutionized the field of sexual medicine and PDe51s are currently first-line monotherapy for erectile dysfunction （eD）. However, a significant proportion of patients with complex eD will be therapeutic non-responders to PDe51 monotherapy. Combination therapy has recently been adopted for more refractory cases of eD, but a critical evaluation of current combination therapies is lacking. A thorough PubMed and Cochrane Library search was conducted focusing on the effectiveness of combination therapies for eD in therapeutic non-responders to PDe51 therapy. Journal articles spanning the time period between January 1990 and December 2010 were reviewed. Criteria included all pertinent review articles, randomized controlled trials, cohort studies and retrospective analyses. references from retrieved articles were also manually scanned for additional relevant publications. Published combination therapies include PDe51 plus vacuum erectile device （VeD）, intraurethral medication, intracavernosal injection （ICI）, androgen supplement, a-blocker or miscellaneous combinations. Based on this review, some of these combination treatments appeared to be quite effective in preliminary testing. Caution must be advised, however, as the majority of combination therapy articles in the last decade have numerous limitations including study biases and small subject size. regardless of limitations, present combination therapy research provides a solid foundation for future studies in complex eD management.

关键词： combination therapy intracavernosal injection erectile dysfunction phosphodiesterase-5 inhibitors vacuum erectile device

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Design of a water curtain to reduce accumulations of float coal dust in longwall returns

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International Journal of Mining Science and Technology 2020年第4期30卷 443-447页

作者： Clara e.Seaman Michael r.Shahan Timothy W.Beck steven e.Mischler National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

Accumulation of float coal dust(FCD)in underground mines is an explosion hazard that affects all underground coal mine *** this hazard is addressed by the application of rock dust,inadequate rock dusting practices can leave miners exposed to an explosion *** at the National Institute for Occupational Safety and Health(NIOSH)have focused on developing a water curtain that removes FCD from the airstream,thereby reducing the buildup of FCD in mine *** this study,the number and spacing of the active sprays in the water curtain were varied to determine the optimal configuration to obtain peak knockdown efficiency(Ke)while minimizing water consumption.

关键词： Float coal dust Longwall Water spray Knockdown efficiency explosion prevention Dust control

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Scales of snow depth variability in high elevation rangeland sagebrush

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Frontiers of earth Science 2017年第3期11卷 469-481页

作者： Molly e. TeDeSCHe steven r. FASSNACHT Paul J. MeIMAN Watershed Science Department of Ecosystem Science and Sustainability Colorado State University Fort Collins CO 80523-1476 USA Intemational Arctic research Center Water & Environmental Research Center Institute of Northern Engineering University of Alaska Fairbanks Fairbanks AK 99775 USA Cooperative Institute for research in the Atmosphere Fort Collins CO 80523-1375 USA Natural resources ecology Laboratory Fort Collins CO 80523-1499 USA Abt. Kartographie GIS & Femerkundung Geographisches Institut Georg-August-Universitat Gottingen 37077 Gottingen Germany rangeland ecosystem Science Department of Forest and Rangeland Stewardship Colorado State University Fort Collins CO 80523 USA

In high elevation semi-arid rangelands, sage- brush and other shrubs can affect transport and deposition of wind-blown snow, enabling the formation of snowdrifts. Datasets from three field experiments were used to investigate the scales of spatial variability of snow depth around big mountain sagebrush （Artemisia tridentata Nutt.） at a high elevation plateau rangeland in North Park, Colorado, during the winters of 2002, 2003, and 2008. Data were collected at multiple resolutions （0.05 to 25 m） and extents （2 to 1000 m）. Finer scale data were collected specifically for this study to examine the correlation between snow depth; sagebrush microtopogra- phy, the ground surface, and the snow surface, as well as the temporal consistency of snow depth patterns. Vario- grams were used to identify the spatial structure and the Moran＇s I statistic was used to determine the spatial correlation. results show some temporal consistency in snow depth at several scales. Plot scale snow depth variability is partly a function of the nature of individual shrubs, as there is some correlation between the spatial structure of snow depth and sagebrush, as well as between the ground and snow depth. The optimal sampling resolution appears to be 25-cm, but over a large area, this would require a multitude of samples, and thus a random stratified approach is recommended with a fine measurement resolution of 5-cm.

关键词： snow hydrology high elevation rangelands,spatial statistics variograms snow pack spatial variability,snow drifts

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eastern Asian endemic seed plant genera and their paleogeographic history throughout the Northern Hemisphere

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Journal of Systematics and evolution 2009年第1期47卷 1-42页

作者： steven r.MANCHeSTer Kazuhiko UeMUrA Florida Museum of Natural History University of Florida National Museum of Nature and Science

We review the fossil history of seed plant genera that are now endemic to eastern Asia. Although the majority of eastern Asian endemic genera have no known fossil record at all, 54 genera, or about 9%, are reliably kn... 详细信息

ract>We review the fossil history of seed plant genera that are now endemic to eastern Asia. Although the majority of eastern Asian endemic genera have no known fossil record at all, 54 genera, or about 9%, are reliably known from the fossil record. Most of these are woody (with two exceptions), and most are today either broadly east Asian, or more specifically confined to Sino-Japanese subcategory rather than being endemic to the Sino-Himalayan area. Of the "eastern Asian endemic" genera so far known from the fossil record, the majority formerly occurred in europe and/or North America, indicating that eastern Asia served as a late Tertiary or Quaternary refugium for taxa. Hence, many of these genera may have originated in other parts of the Northern Hemisphere and expanded their ranges across continents and former sea barriers when tectonic and climatic conditions al- lowed, leading to their arrival in eastern Asia. Although clear evidence for paleoendemism is provided by the gymnosperms Amentotaxus, Cathaya, Cephalotaxus, Cunninghamia, Cryptomeria, Glyptostrobus, Ginkgo, Ketel-eeria, Metasequoia, Nothotsuga, Pseudolarix, Sciadopitys, and Taiwania, and the angiosperms Cercidiphyllum, Choerospondias, Corylopsis, Craigia, Cyclocarya, Davidia, Dipelta, Decaisnea, Diplopanax, Dipteronia, em-menopterys, eucommia, euscaphis, Hemiptelea, Hovenia, Koelreuteria, Paulownia, Phellodendron, Platycarya, Pteroceltis, rehderodendron, Sargentodoxa, Schizophragma, Sinomenium, Tapiscia, Tetracentron, Toricellia, Trapella, and Trochodendron, we cannot rule out the possibility that neoendemism plays an important role especially for herbaceous taxa in the present-day flora of Asia, particularly in the Sino-Himalayan region. In addition to reviewing paleobotanical occurrences from the literature, we document newly recognized fossil occurrences that expand the geographic and stratigraphic ranges previously known for Dipelta, Pteroceltis, and Toricellia.

关键词： Cretaceous eastern Asia endemic paleobotany phytogeography Tertiary

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DNA alkylation promoted by an electron-rich quinone methide intermediate

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Frontiers of Chemical Science and engineering 2016年第2期10卷 213-221页

作者： Chengyun Huang steven e. rokita Department of Chemistry and Biochemistry University of Maryland College Park MD 20742 USA Sichuan Institute of Geological engineering Investigation Chengdu 610072 China Department of Chemistry Johns Hopkins University Baltimore MD 21218 USA

Biological application of conjugates derived from oligonucleotides and quinone methides have pre- viously been limited by the slow exchange of their covalent self-adducts and subsequent alkylation of target nucleic acids. To enhance the rates of these processes, a new quinone methide precursor with an electron donating substituent has been prepared. Additionally, this substi- tuent has been placed para to the nascent exo-methylene group of the quinone methide for maximum effect. A conjugate made from this precursor and a 5＇-aminohex- yloligonucleotide accelerates formation of its reversible self-adduct and alkylation of its complementary DNA as predicted from prior model studies.

关键词： quione methide DNA alkylation reversible covalent reaction bioconjugation target-directed modification of nucleic acids

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Pathophysiology and treatment of Barrett's esophagus

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World Journal of Gastroenterology 2010年第30期16卷 3762-3772页

作者： Daniel S Oh steven r DeMeester Department of Surgery The University of Southern CaliforniaKeck School of MedicineLos AngelesCA 90033United States

Gastroesophageal reflux disease (GerD) affects an estimated 20% of the population in the United States. About 10%-15% of patients with GerD develop Barrett’s esophagus, which can progress to adenocarcinoma, currently the most prevalent type of esophageal cancer. The esophagus is normally lined by squamous mucosa, therefore, it is clear that for adenocarcinoma to develop, there must be a sequence of events that result in transformation of the normal squamous mucosa into columnar epithelium. This sequence begins with gastroesophageal reflux, and with continued injury metaplastic columnar epithelium develops. This article reviews the pathophysiology of Barrett’s esophagus and implications for its treatment. The effect of medical and surgical therapy of Barrett’s esophagus is compared.

关键词： Gastroesophageal reflux disease Barrett’s esophagus Lower esophageal sphincter esophageal motility Proton pump inhibitors Antireflux surgery

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Culture conditions for equine bone marrow mesenchymal stem cells and expression of key transcription factors during their differentiation into osteoblasts

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Journal of Animal Science and Biotechnology 2014年第2期5卷 163-172页

作者： elizabeth r A Glynn Alfredo Sanchez Londono steven A Zinn Thomas A Hoagl Kristen e Govoni Department of Animal Science University of Connecticut3636 Horsebarn Road Ext.Unit 4040StorrsCT 06269-4040USA Department of environmental and Population Health Tufts University North GraftonMA 01536USA

Background： The use of equine bone marrow mesenchymal stem cells （BMSC） is a novel method to improve fracture healing in horses. However, additional research is needed to identify optimal culture conditions and to determine the mechanisms involved in regulating BMSC differentiation into osteoblasts. The objectives of the experiments were to determine： 1） if autologous or commercial serum is better for proliferation and differentiation of equine BMSC into osteoblasts, and 2） the expression of key transcription factors during the differentiation of equine BMSC into osteoblasts. equine BMSC were isolated from the sterna of 3 horses, treated with purchased fetal bovine serum （FBS） or autologous horse serum （HS）, and cell proliferation determined. To induce osteoblast differentiation, cells were incubated with L-ascorbic acid-2-phosphate and glycerol-2-phosphate in the presence or absence of human bone morphogenetic protein2 （BMP2）, dexamethasone （DeX）, or combination of the two. Alkaline phosphatase （ALP） activity, a marker of osteoblast differentiation, was determined by eLISA. Total rNA was isolated from differentiating BMSC between d 0 to 18 to determine expression of runt-reloted tronscrJption foctor2 （runx2）, osterix （Osx）, and T-box3 （Tbx3）. Data were analyzed by ANOVA. results： relative to control, FBS and HS increased cell number （133 ± 5 and 116 ± 5%, respectively; P 〈 0.001） and 5-bromo- 2＇-deoxyuridine （BrdU） incorporation （167 ± 6 and 120 ± 6%, respectively; P 〈 0.001）. Treatment with DeX increased ALP activity compared with control （1,638 ± 38%; P 〈 0.001）. In the absence and presence of Dex, BMP-2 did not alter ALP activity （P 〉 0.8）. runt-reloted transcription foctor2 expression increased 3-fold （P 〈 0.001） by d 6 of culture. Osterix expression increased 94old （P 〈 0.05） by d 18 of culture. expression of Tbx3 increased 1.8-fold at d 3 （P 〈 0.01）; however expression was reduced 4-fold at d 18 （P 〈 0.01）. Conclusions： Dexamethasone, but not BMP-2, is requir

关键词： Bone marrow mesenchymal stem cells Cell culture equine Osteoblasts Transcription factors

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