196,127 research outputs found
ASTROCYTES FROM ADULT-RAT OPTIC NERVES ARE NONPERMISSIVE FOR REGENERATING RETINAL GANGLION-CELL AXONS
No full textWe have directly compared the abilities of astrocytes from newborn and adult rats to support or inhibit the growth of regenerating axons in vitro. Astrocytes prepared from newborn rats were able to promote retinal ganglion cell (RGC) axon growth from embryonic and adult rat and from adult fish retinal explants. Retinal axons from E16 rat retinae grew significantly faster on astrocytes from neonatal rats than those from E18 or adult rat retinae with growth rates comparable to RGC axons from adult fish retinae. RGC regeneration from adult rat retinae was almost completely inhibited on adult rat optic nerve astrocytes. Only axons from adult fish retinae were able to extend onto monolayers from these reactive astrocytes, although their growth rates were significantly reduced. We conclude that the failure of mammalian RGC axons to regrow within the lesioned optic nerve environment is, at least in part, due to nonpermissive aspects of adult 'reactive' optic nerve astrocytes. However, the cell intrinsic growth potential of RGCs also appears to influence their ability to extend axons on cellular substrates. (C) 1995 Academic Press, Inc
Fish optic nerve oligodendrocytes support axonal regeneration of fish and mammalian retinal ganglion cells
No full textSegments from adult fish and rat retinae were explanted on myelin-marker expressing oligodendrocytes derived from the regenerating goldfish optic nerve. Fish axons grew in high density and even rat retinal axons regenerated to considerable length on the surface of the fish oligodendrocytes, suggesting that this type of fish glia has axon-growth promoting surface components that exert their influence across species boundaries. One interesting surface component of the fish oligodendrocytes as demonstrated here is the E 587 antigen, which is related to the L1 family of cell adhesion molecules.In long term cocultures of oligodendrocytes and retinal axons, the fish glial cells were found to enwrap rat axons. This suggests that the oligodendrocytes of the regenerating goldfish optic nerve/tract may, despite striking differences, represent the equivalent to mammalian optic nerve oligodendrocytes.publishe
Expression of JUN, KROX, and CREB transcription factors in goldfish and rat retinal ganglion cells following optic nerve lesion is related to axonal sprouting
No full textGoldfish and rat optic nerves were cut and crushed, respectively, and the expression of the transcription factor proteins c-JUN, JUN B, JUN D, c-FOS, FOS B, KROX-24, and CREB was investigated in retinal ganglion cells (RGCs) by immunocytochemistry. Immunoreactivities (IRs) were followed up to 350 days in the goldfish and upto 22 days in the rat. In RGCs of untreated goldfish and rats, all JUN, FOS, and KROX proteins were absent whereas CREB was constitutively expressed. After optic nerve cut in goldfish, a JUN-like immunoreactivity (JUN-IR) appeared in a small number of RGCs of central retina after 24 h, reached a maximum within 5 days, declined after 30 days, and was on a half-maximal level after 50 days. Between 100 and 200 days, JUN-IR was only visible in a few RGCs and was completely absent after 350 days. Specific antibodies against c-JUN, JUN B, and JUN D gave no distinct immunoreactive signal. Thus, we could not determine which member of the JUN family contributed to the JUN-IR. The expression of CREB declined after 5 days. The number of CREB-labeled RGCs was reduced (not significant) and the intensity of labeling faded out. After 50 days, CREB-IR had returned to basal level. c-FOS, FOS B, and KROX-24 could not be detected in goldfish RGCs following optic nerve cut. After optic nerve crush in the rat, c-JUN, JUN D, and KROX-24 appeared in a substantial number of RGCs after 24 h, had a maximal expression after 5 days, and strongly declined after 8 days. c-JUN and KROX-24 were completely absent after 22 days whereas JUN D was still present in a few rat RGCs. The number of CREB-labeled RGCs decreased after 5 days and had declined by 50% after 22 days. Expression of JUN B, c-FOS, FOS B could not be detected in rat RGCs after optic nerve crush. Our data demonstrate that the decrease of CREB and the increase of JUN and KROX-24 transcription factors precedes and parallels both the alteration of de novo protein synthesis and the axonal sprouting, which are long lasting in goldfish and transient in rat.publishe
Acrylamide-based copolymers bearing photoreleasable thiols for subsequent thiol-ene functionalization
No full textA new set of monomers is presented in order to incorporate thiols into radical polymers using a protecting chemistry/photocleavage route. The (co)polymerization kinetics of an o-nitrobenzyl thioether-containing acrylamide derivative are reported. The presence of the o-nitrobenzyl moiety is found to strongly affect the polymerization. Nevertheless, water-soluble copolymers with N,N-dimethylacrylamide (DMAAm) as a comonomer are obtained either by free radical polymerization (10 000 ≤ M n ≤ 17 500 g mol -1; 1.5 ≤ PDI ≤ 1.8) or by reversible addition-fragmentation transfer (RAFT)-mediated controlled/living radical polymerization (2000 ≤ M n ≤ 5700 g mol -1; 1.1 ≤ PDI ≤ 1.2). Deprotection under UV light (λ = 366 nm) at ambient temperature is followed by UV/vis monitoring of the protecting group release, which proceeds to completion between 40 min and 2 h within the studied range of concentration as demonstrated by 1H NMR spectroscopy. Thiol-maleimide addition is subsequently carried out and found to proceed with a nearly quantitative yield (ca. 90%) as measured by 1H NMR. Different block copolymers (9400 ≤ M n ≤ 16 500 g mol -1; 1.3 ≤ PDI ≤ 1.4) with a PDMAAm water-soluble block, a polystyrene hydrophobic block, or a poly(N-isopropylacrylamide) thermosensitive block as the first segment and possessing the photoreleasable thiol moieties in the second block are subsequently synthesized by RAFT-mediated polymerization. We finally demonstrate the orthogonal sequential deprotection and reaction with benzyl maleimide of two different thiol species originating from the thiocarbonylthio functionality and the o-nitrobenzyl protected lateral groups, respectively. © 2012 American Chemical Society
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Bachmann et al., pPax and pFAK, Journal of Cell Science, 2022
No full textDeposit for: "Phosphorylated paxillin and phosphorylated FAK constitute subregions within focal adhesions", by M. Bachmann, A. Skripka, K. Weißenbruch, B. Wehrle-Haller, M. Bastmeyer
accepted in Journal of Cell Science, 202
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
Full text linkFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
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