1,721,796 research outputs found
Overview of mesenchymal stem cells
No full textStem cells are unprogrammed cells which possess plasticity and self renewal capability. The term of stem cell was first used to describe cells committed to give rise to germline cells, and to describe proposed progenitor cells of the blood system [1]. A unique feature of stem cell is to remain quiescent in vivo in an uncommitted state. They serve as reservoir or natural support system to replenish cells lost due to disease, injury or aging. When triggered by appropriate signals these cells divide and may become specialized, committed cells; however being able to control this differentiation process still remains one of the biggest challenge in stem cell research [2]. The cell division of stem cells is a distinct aspect of their biology, since this division may be either symmetric or asymmetric. Symmetric division takes place when the stem cells divides and forms two new daughter cells. Asymmetric division is thought to take place only under certain conditions where stem cells divides and gives rise to a daughter cell which remains primitive and does not proliferate, and one committed progenitor cell, which heads down a path of differentiation. Asymmetric division of stem cells helps reparative process, and also ensures that the stem cells pool does not decrease, whereas symmetric division is responsible for stem cells undergoing self renewal and proliferation. The factors which prompt the stem cells to undergo asymmetric division are, however, not well understood, but it is clear that the delicate balance between the self renewal and differentiation is what maintains tissue homeostasis
Periodontal regeneration and mesenchymal stem cells
No full textThe ultimate goal of periodontal therapy is to regenerate periodontal supporting tissues, but this is hard to achieve as the results of periodontal techniques for regeneration are clinically unpredictable. Stem cells owing to their plasticity and proliferation potential provides a new paradigm for periodontal regeneration. Stem cells from mesenchyme can self renew and generate new dental tissues (including dentin and cementum), alveolar bone and periodontal ligament, and thus they have great potential in periodontal regeneration. This chapter presents an insight into mesenchymal stem cells and their potential use in periodontal regeneration. In this chapter the cellular and molecular biology in periodontal regeneration will be introduced, followed by a range of conventional surgical procedures for periodontal regeneration will be discussed. Mesenchymal stem cells applied in regenerated periodontal tissue and their biological characterizations in vitro will be also introduced. Lastly, the use of mesenchymal stem cell to repair periodontal tissues in large animal models will be also reviewed
Mesenchymal stem cells in osteoarthritis therapy : current status of theory, technology, and applications
No full textOsteoarthritis (OA) is a chronic, non-inflammatory type of arthritis, which usually affects the movable and weight bearing joints of the body. It is the most common joint disease in human beings and common in elderly people. Till date, there are no safe and effective diseases modifying OA drugs (DMOADs) to treat the millions of patients suffering from this serious and debilitating disease. However, recent studies provide strong evidence for the use of mesenchymal stem cell (MSC) therapy in curing cartilage related disorders. Due to their natural differentiation properties, MSCs can serve as vehicles for the delivery of effective, targeted treatment to damaged cartilage in OA disease. In vitro, MSCs can readily be tailored with transgenes with anti-catabolic or pro-anabolic effects to create cartilage-friendly therapeutic vehicles. On the other hand, tissue engineering constructs with scaffolds and biomaterials holds promising biological cartilage therapy. Many of these strategies have been validated in a wide range of in vitro and in vivo studies assessing treatment feasibility or efficacy. In this review, we provide an outline of the rationale and status of stem-cell-based treatments for OA cartilage, and we discuss prospects for clinical implementation and the factors crucial for maintaining the drive towards this goal
FIG. 5 Sarsia piriforma Edwards, 1983 A and B in Two new species and four new records of the Sarsia tubulosa group of Sarsia (Cnidaria, Corynidae) from the Bohai Sea of China
No full textFIG. 5 Sarsia piriforma Edwards, 1983 A and B. Lateral viewPublished as part of Wang, Xiao, Chen, Xiao-Yin & Xu, Zhen-Zu, 2022, Two new species and four new records of the Sarsia tubulosa group of Sarsia (Cnidaria, Corynidae) from the Bohai Sea of China, pp. 243-254 in Zootaxa 5189 (1) on page 249, DOI: 10.11646/zootaxa.5189.1.22, http://zenodo.org/record/711951
FIG. 3 in Two new species and four new records of the Sarsia tubulosa group of Sarsia (Cnidaria, Corynidae) from the Bohai Sea of China
No full textFIG. 3 Sarsia macrogastera Xu, Chen, & Wang sp. nov. A and B. lateral view; C. tentacle bulbs in frontal view.; D. tentacle bulbs in lateral view.Published as part of Wang, Xiao, Chen, Xiao-Yin & Xu, Zhen-Zu, 2022, Two new species and four new records of the Sarsia tubulosa group of Sarsia (Cnidaria, Corynidae) from the Bohai Sea of China, pp. 243-254 in Zootaxa 5189 (1) on page 247, DOI: 10.11646/zootaxa.5189.1.22, http://zenodo.org/record/711951
Formal synthesis of (+)-FR900482
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.Vita.Includes bibliographical references.A tandem benzannulation-ring closing metathesis strategy for the efficient synthesis of benzo-fused nitrogen heterocycles such as dihydroquinolines, benzazepines, and benzazocines has been developed. This strategy is based on the benzannulation reaction of ynamides with cyclobutenones or [alpha]-diazo ketones to generate highly-substituted aniline derivatives, which then participate in ring-closing metathesis reactions to form nitrogen heterocycles. The synthetic utility of this strategy has been demonstrated by its successful application in a formal synthesis of the natural product (+)-FR900482. In addition, an environmentally-friendly approach to the synthesis of amides and lactams has been developed using supercritical carbon dioxide as a 'green' replacement solvent. The amide products are generated from the addition of amines to ketenes, which are formed in situ from the retro-ene reaction of alkynyl ethers.by Xiao Yin Mak.Ph.D
Grandilithus nonggan g (Liu, Xu, Xiao, Yin & Peng 2019
No full text<p> <i> <i>Grandilithus nonggan</i> g</i> <b>(Liu, Xu, Xiao, Yin & Peng, 2019)</b></p> <p>(Figs 3, 21)</p> <p> <i>Otacilia nonggang</i> Liu <i>et al.</i>, 2019: 449, figs 11−13 (♁ ♀, type deposition in HNU).</p> <p> <i>Grandilithus nonggang</i>: Liu <i>et al.</i>, 2022: Suppl. 2: 39, figs 135a−d, 136d−f (Transfer from <i>Otacilia</i>)</p> <p> <b>Material examined.</b> China, Guangxi Zhuang Autonomous Region, Nanning City, Shanglin County, Damingshan National Natural Reserve. 1 ♁, 2 ♀: Ganlan Station, 23°33'1.08"N, 108°25'37.03"E, 501, 7.11.2018; 4 ♀: Xiyan Station, Shuiyuan Village, 23°24'39.88"N, 108°31'48.33"E, 517 m, 9.11.2018; 1 ♁: Jilong Station, 23°26'5.27"N, 108°26'32.64"E, 591 m, 5.11.2018. Holotype examined.</p> <p> <b>Diagnosis and description.</b> See Liu <i>et al.</i> (2019) for both sexes. Male palp as in Fig. 3A, B.</p> <p> <b>Supplement data.</b> Retrolateral tibial apophysis (RTA) with the tip bent at a right-angle in ventral view (Fig. 3A). Retrolateral tegular apophysis (rTA) with a broad base and thin apex (Fig. 3B).</p> <p> <b>Distribution.</b> Known only from Guangxi Zhuang Autonomous Region, China (Fig. 21).</p>Published as part of <i>Liu, Keke, Xu, Xiang & Yin, Haiqiang, 2023, A survey of the Phrurolithidae (Arachnida: Araneae) of Damingshan National Natural Reserve, south China, pp. 511-536 in Zootaxa 5278 (3)</i> on page 514, DOI: 10.11646/zootaxa.5278.3.5, <a href="http://zenodo.org/record/7906649">http://zenodo.org/record/7906649</a>
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