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Autologous fibrin-cultured limbal stem cells permanently restore the corneal surface of patients with total limbal stem cell deficiency
No full textBACKGROUND: Ocular burns cause depletion of limbal stem cells, which leads to corneal opacification and visual loss. Autologous cultured epithelial cells can restore damaged corneas, but this technology is still developing. We sought to establish a culture system that allows preservation of limbal stem cells and preparation of manageable epithelial sheets and to investigate whether such cultures can permanently restore total limbal stem cell deficiency. METHODS: We selected a homogeneous group of patients whose limbal cell deficiency was evaluated by scoring the gravity of the clinical picture and the keratin expression pattern. Stem cells, obtained from the limbus of the contralateral eye, were cultivated onto a fibrin substrate and their preservation was evaluated by clonal analysis. Fibrin cultures were grafted onto damaged corneas. RESULTS: Fibrin-cultured limbal stem cells were successful in 14 of 18 patients. Re-epithelialization occurred within the first week. Inflammation and vascularization regressed within the first 3-4 weeks. By the first month, the corneal surface was covered by a transparent, normal-looking epithelium. At 12-27 months follow-up, corneal surfaces were clinically and cytologically stable. Three patients had a penetrating keratoplasty approximately 1 year after restoration of their corneal surface. Their visual acuity improved from light perception or counting fingers to 0.8-1.0. CONCLUSIONS: Preservation of limbal stem cells in culture gives new perspectives on the treatment of ocular disorders characterized by complete limbal stem cell deficiency. The multicenter nature of this study and the handiness and ease of long-distance transportation of the fibrin-cultured epithelial sheets suggest that this technology can now be widely applied
Autologous fibrin-cultured limbal stem cells permanently restore the corneal surface of patients with total limbal stem cell deficiency
No full textOcular burns cause depletion of limbal stem cells, which leads to corneal opacification and visual loss. Autologous cultured epithelial cells can restore damaged corneas, but this technology is still developing. We sought to establish a culture system that allows preservation of limbal stem cells and preparation of manageable epithelial sheets and to investigate whether such cultures can permanently restore total limbal stem cell deficiency
Location and clonal analysis of stem cells and their differentiated progeny in the human ocular surface. [5YIF: 10.77; Citations: 429]
No full textWe have analyzed the proliferative and differentiation potential of human ocular keratinocytes. Holoclones, meroclones, and paraclones, previously identified in skin, constitute also the proliferative compartment of the ocular epithelium. Ocular holoclones have the expected properties of stem cells, while transient amplifying cells have variable proliferative potential. Corneal stem cells are segregated in the limbus, while conjunctival stem cells are uniformly distributed in bulbar and forniceal conjunctiva. Conjunctival keratinocytes and goblet cells derive from a common bipotent progenitor. Goblet cells were found in cultures of transient amplifying cells, suggesting that commitment for goblet cell differentiation can occur late in the life of a single conjunctival clone. We found that conjunctival keratinocytes with high proliferative capacity give rise to goblet cells at least twice in their life and, more importantly, at rather precise times of their life history, namely at 45-50 cell doublings and at approximately 15 cell doublings before senescence. Thus, the decision of conjunctival keratinocytes to differentiate into goblet cells appears to be dependent upon an intrinsic "cell doubling clock. " These data open new perspectives in the surgical treatment of severe defects of the anterior ocular surface with autologous cultured conjunctival epithelium
Study on the interaction between the skin detoxifying enzyme glutathione S-transferase and the substances listed in the CE/39/2000 rules with the "skin" annotation, finalized to the biological monitoring of exposed subjects
No full textThe interaction among chemicals listed in the Directive CE/39/2000 with skin notation and glutathione S-transferase (GSTP1-1) was studied by following two different experimental approaches. The compounds were incubated with the purified GST isoenzyme GSTP1-1 as well as with the human keratinocytes (PR5) selectively expressing GSTP1-1. Some of the molecules affected the enzymatic activity of both the purified and the intracellular GSTP1-1. In particular, 1,2-dichlorobenzene (DCB), ethylbenzene (ETB), cumene, Sulphotep and 2-eptanone (2-EPT) behaved as inhibitors of the purified GSTP1-1 enzyme, with different inhibition properties according to molecular structure. With the exception of Sulphotep showing a Ki value of 0.2 mM, all compounds reported above were characterized by high Ki values (between 2 and 16 mM) and therefore by low affinity towards GSTP1-1. These results make unlikely the use of a biosensor, based on immobilized GSTP1-1, for the detection of these molecules. On the contrary, Sulphotep can be the object of future investigations. It has to be stressed that the above listed compounds were effective on human keratinocytes, at concentrations two order of magnitude lower than that effective on purified GSTP1-1. In particular, cumene and DCB triggered a clear increase of the intracellular GSTP1-1 activity at concentrations lower than 0.1mM. These interesting results let to hypothesize the use of GSTP1-1 present in the keratinocytes as a marker for biological monitoring of workers exposed to these compounds as well as to evaluate the skin permeability of toxic compounds, not yet identified with a skin notation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Reconstruction of the corneal epithelium: preliminary results
No full texthttp://hdl.handle.net/20.500.11768/9683
Telomerase activity is sufficient to bypass replicative senescence in human limbal and conjunctival but not corneal keratinocytes.
No full text- …
