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Cortical Interlaminar Astrocytes Are Generated Prenatally, Mature Postnatally, and Express Unique Markers in Human and Nonhuman Primates
Get PDFInterlaminar astrocytes (ILAs) are a subset of cortical astrocytes that reside in layer I, express GFAP, have a soma contacting the pia, and contain long interlaminar processes that extend through several cortical layers. We studied the prenatal and postnatal development of ILAs in three species of primates (rhesus macaque, chimpanzee, and human). We found that ILAs are generated prenatally likely from radial glial (RG) cells, that ILAs proliferate locally during gestation, and that ILAs extend interlaminar processes during postnatal stages of development. We showed that the density and morphological complexity of ILAs increase with age, and that ILAs express multiple markers that are expressed by RG cells (Pax6, Sox2, and Nestin), specific to inner and outer RG cells (Cryab and Hopx), and astrocyte markers (S100β, Aqp4, and GLAST) in prenatal stages and in adult. Finally, we demonstrated that rudimentary ILAs in mouse also express the RG markers Pax6, Sox2, and Nestin, but do not express S100β, Cryab, or Hopx, and that the density and morphological complexity of ILAs differ between primate species and mouse. Together these findings contribute new information on astrogenesis of this unique class of cells and suggest a lineal relationship between RG cells and ILAs
Isolation, expansion and characterization of single mesenchymal stem cells
No full textThesis (M.S., Biological Sciences (Molecular and Cellular Biology)) -- California State University, Sacramento, 2010.Mesenchymal Stem Cells (MSCs) are multipotent precursors to many mesodermal cell lineages in vertebrate animals and are most often obtained from bone marrow. Certain attributes of MSCs, including migration toward sites of inflammation, ease of transduction, and lack of immunogenicity, suggest these cells may be potentially useful for regenerative medicine. Putative therapeutic uses include regeneration of damaged tissue, acting as a vessel for delivering a therapeutic transgene, support of other cell types for tissue repair, and modulating the immune reaction to co-transplanted cells or tissues. However, MSCs lack distinctive surface markers and conventional MSC culture has been shown to be heterogeneous. A thorough characterization of MSC culture at a single cell level has not been adequately demonstrated. These conditions lead to the question of whether there are true mesenchymal ???stem??? cells, or simply a mixed population of committed mesenchymal progenitors. In addition to being an important question in MSC biology, this may prove to be an important distinction in certain therapeutic settings. In this study, the methods used to identify hematopoietic high proliferative potential-colony forming cells (HPP-CFCs) and high proliferative potential- endothelial colony forming cells (HPP-ECFCs), were adapted to investigate the existence of high proliferative potential-mesenchymal colony forming cells (HPP-MCFCs), and the differentiation potential of these cells toward adipogenic, chondrogenic, and osteogenic lineages at a single cell level. This study demonstrates for the first time that a hierarchy of mesenchymal cells within conventional MSC culture can be described, and single HPP-MCFCs can differentiate toward adipogenic, chondrogenic and osteogenic lineages as well as form secondary colonies.Biological Sciences (Molecular and Cellular Biology
Optimizing differentiation of alveolar epithelial cells from human induced pluripotent stem cells
No full textPediatric lung disorders are a leading cause of illness and death in infants and children. These diseases are poorly understood and there are few treatment options available. For example, infants born with hereditary surfactant protein-B (SP-B) deficiency will die within a year after birth without a lung transplantation. SP-B is an essential component of pulmonary surfactant, secreted by alveolar epithelial type II cells (AEC II). Potential therapeutic strategies under development to correct SP-B deficiency include the use of human induced pluripotent stem cell (hiPSC)-derived lung precursors if methods can be optimized to derive AEC II cells of sufficient purity and quantity. The goal of this project was to optimize differentiation and expansion of hiPSC-derived definitive endoderm (DE), the first stage for AEC II specificity, using novel scaffold culture systems. A lentiviral vector was used to transduce hiPSC to express the reporter genes firefly luciferase and the enhanced green fluorescent protein (eGFP). An established well-tested bank of hiPSC expressing these reporter genes were used for these studies. Monolayer cultures or embryoid body (EB) cultures were supplemented with Activin A (100 ng/mL) for 4 days to direct cells to definitive endoderm (DE). Directed differentiation of hiPSC in EB culture increased expression of DE markers SOX17 (19-fold; p<0.05), FOXA2 (13-fold), CXCR4 (81-fold), and GATA4 (38-fold) compared to standard monolayer cultures. To enhance differentiation and expansion to DE, biologically inert, biodegradable hyper-crosslinked carbohydrate polymer scaffolds (HCCP) were used to evaluate cellular attachment. These results showed that decellularized lung scaffolds were more effective for cellular attachment and migration compared to HCCP scaffolds. Analysis of protein expression showed a rapid upregulation of DE markers by day 3 in recellularized lung scaffolds. Previous studies in the lab show that bioactive molecules are retained in the decellularized lung scaffold other than proteins of the extracellular matrix. Since HCCP scaffolds provide a controlled environment, they will be important in future studies to determine which bioactive molecules are important for enhancing DE differentiation. Overall, our studies demonstrate the importance of cell – cell interactions for DE differentiation in vitro, which are not captured in standard monolayer cultures. In addition, our studies provide a basis for optimizing AEC II from hiPSC. Ultimately, the goal is to optimize each stage of AEC II differentiation for use in pre-clinical studies of engraftment and function for the treatment of disorders such as hereditary SP-B deficiency and other pediatric lung disorders
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ultrasound Imaging in Rhesus (Macaca mulatta) and Long-tailed (Macaca fascicularis) Macaques: Reproductive and Research Applications
No full textVariations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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