O rádio educativo como estratégia de andaime em ciências naturais: uma experiência com alunos de 3ª e 4ª séries da Instituição Educacional Samurindó

This research addressed the experience carried out in the Educational Institution Samurindó (Chocó-Colombia) in which they were analyzed the intentions of scaffolding perceived by students of third and fourth grade after listening to the radio program that develops educational content in natural sciences. The study takes advantage of the potential of educational radio as a scaffolding strategy, applying a variety of techniques and teaching means that are used to progressively move them towards a deeper understanding and greater independence in the learning process. The methodology used in the research is exploratory-interpretive where the assessment of the perceptions of students and teachers about the intentions promoted in the radio programs is carried out.  The results of the study found that most of the participants are satisfied with the support provided by these programs for the learning of contents of the natural sciences, being the session of the radio soap opera the one with the greatest acceptance by the students.  However, the format of the radio no longer fits into the culture of the young generations (They are distracted in other activities), in addition the conditions of the physical plant of the Samurindó Educational Institution made it difficult for them to listen in this format. Esta investigación abordó la experiencia llevada a cabo en la Institución Educativa Samurindó (Chocó - Colombia) en la cual se analizaron las intenciones de andamiaje que perciben los estudiantes de tercero y cuarto de primaria luego de escuchar el programa radial que desarrolla contenido educativo en ciencias naturales. El estudio aprovecha el potencial que tiene la radio educativa como estrategia de andamiaje, aplicando una variedad de técnicas y medios de enseñanza que son utilizadas para moverlos progresivamente hacia una comprensión más profunda y una mayor independencia en el proceso de aprendizaje. La metodología utilizada en la pesquisa es de carácter exploratorio-interpretativo donde se realiza la valoración de las percepciones de estudiantes y maestras sobre las intenciones que se promueven en los programas radiales. Los resultados del estudio muestran que la mayoría de  los participantes están satisfechos con el apoyo brindado por estos programas para el aprendizaje de contenidos de las ciencias naturales, siendo la sesión de la radionovela la de mayor aceptación por parte de los estudiantes. Sin embargo, el formato de la radio ya no encaja en la cultura de las jóvenes generaciones (se distraen en otras actividades), además las condiciones de la planta física de la Institución Educativa Samurindó les dificultaba la escucha en dicho formato.Esta pesquisa abordou a experiência realizada na Instituição de Ensino Samurindó (Chocó-Colombia) na qual foram analisadas as intenções de andaimes percebidos pelos alunos do 3º e 4º ano após ouvir o programa de rádio que desenvolve conteúdo educacional em ciências naturais. O estudo aproveita o potencial do rádio educacional como estratégia de andaimes, aplicando uma variedade de técnicas e meios de ensino que são usados para movê-los progressivamente para uma compreensão mais profunda e maior independência no processo de aprendizagem. A metodologia utilizada na pesquisa é exploratória-interpretativa onde é realizada a avaliação das percepções de alunos e professores sobre as intenções promovidas nos programas de rádio.  Os resultados do estudo constataram que a maioria dos participantes está satisfeita com o apoio prestado por esses programas para a aprendizagem de conteúdos das ciências naturais, sendo a sessão da novela de rádio a que tem maior aceitação pelos alunos.  No entanto, o formato do rádio não se encaixa mais na cultura das novas gerações (elas se distraem em outras atividades), além disso, as condições da planta física da Instituição de Ensino Samurindó dificultaram a escuta nesse formato

Contact guidance enhances the quality of a tissue engineered corneal stroma

Corneal stroma is a very complex structure, composed of 200 lamellae of oriented collagen fibers. This highly complex nature of cornea is known to be important for its transparency and mechanical integrity. Thus, an artificial cornea design has to take into account this complex structure. In this study, behavior of human corneal keratocytes on collagen films patterned with parallel channels was investigated. Keratocytes proliferated well on films and reached confluency after 7 days in the incubation medium. Nearly all of the cells responded to the patterns and were aligned in contrast to the cells on unpatterned surfaces. Collagen type I and keratan sulfate secreted by keratocytes on patterned films appeared to be aligned in the direction of the patterns. The films showed an intermediate degradation over the course of a month. On the whole, transparency of the films increased with degradation and decreased by the presence of the cells. The decrease was, however, low and transparency level was maintained on the patterned films while on the unpatterned films a sharp decrease in transparency was followed by an improvement. This was due to the more organized distribution of cells and the oriented secretion of extracellular matrix molecules on patterned collagen films. Thus, these results suggest that application of contact guidance in cornea tissue engineering may facilitate the remodeling process, hence decrease the rehabilitation period. © 2007 Wiley Periodicals, Inc

Towards the use of hydrogels in the treatment of limbal stem cell deficiency

Corneal blindness caused by limbal stem cell deficiency (LSCD) is a prevailing disorder worldwide. Clinical outcomes for LSCD therapy using amniotic membrane (AM) are unpredictable. Hydrogels can eliminate limitations of standard therapy for LSCD, because they present all the advantages of AM (i.e. biocompatibility, inertness and a biodegradable structure) but unlike AM, they are structurally uniform and can be easily manipulated to alter mechanical and physical properties. Hydrogels can be delivered with minimum trauma to the ocular surface and do not require extensive serological screening before clinical application. The hydrogel structure is also amenable to modifications which direct stem cell fate. In this focussed review we highlight hydrogels as biomaterial substrates which may replace and/or complement AM in the treatment of LSCD

Eye bank issues: II. Preservation techniques: warm versus cold storage

Most of the tissue used for penetrating keratoplasty is issued through eye banks that store the corneoscleral button either in hypothermic storage at 2–6°C or in organ culture at 31–37°C

Ingénierie tissulaire de la cornée (faisabilité)

Nous avons montré que les kératocytes extraits de la moitié supérieure périlimbique du stroma cornéen ont la capacité proliférative maximale dont 70% expriment CD34. Nous avons optimisé un milieu de prolifération permettant de conserver le phénotype CD34 positif. Nous avons mis en évidence 3 interactions des composants du milieu ayant un effet sur la différenciation. Nous avons réalisé un stroma reconstruit et une hémicornée dans lesquels le diamètre et l espacement des fibres de collagènes sont proches de celles de la cornée humaine. L hémicornée a été caractérisée et les interactions entre les cellules épithéliales et les kératocytes apportent un modèle plus physiologique en recherche et en pharmacotoxicologie. Sa présentation en insert de culture permet de faciliter l application de produits à testerWe showed that keratocytes extracted from the perilimbic higher half of the corneal stroma have the maximum proliferative capacity, of which 70% express CD34. We optimized a medium for proliferation allowing to preserve CD34 positive phenotype. We highlighted 3 interactions of the components of the medium having an effect on differentiation. We carried out a stroma reconstruction and an hemicornea in which the diameter and the spacing of collagen fibres are close to those of the human cornea. Hemicornea was characterized and the interactions between the epithelial cells and the keratocytes bring a more physiological model in research and pharmacotoxicology. Its presentation inside culture inserts makes it possible to facilitate the application of products to be testedLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Enseignement en période de pandémie COVID. Le cas de l’UE « initiation à la recherche » chez les étudiants d’électroradiologie médicale.

National audienc

Major endothelial loss from corneas in organ culture: importance of second endothelial count.

International audiencePURPOSE: The aim of this study was to show that major losses can still occur on corneas judged suitable for grafting at the first count. In addition, we studied the frequency of these losses on 1992 corneas over a period of 4 years to evaluate the risk incurred. METHODS: We evaluated the incidence of these major losses and the associated risk factors. An Ishigawa diagram was created with the Cornea Bank team and the ophthalmologists involved in organ retrieval. Endothelial losses caused by bacterial or fungicidal contamination were excluded from the study. For the 29 corneas that suffered major losses, we analyzed the donor files for donor age, clinical file, geographical origins of the corneas, the person who did the retrieval, the length of time the cornea was stored, the data resulting from examining the endothelium at the bank by optical microscope, and the method used for sterilizing the material used. Specific analyses in cases of major loss of endothelial content: anatomopathologic examination of the corneas and search for the herpes simplex virus (HSV; type 1 or 2) by polymerase chain reaction (PCR). We carried out a statistical analysis using a chi(2) test on the 1992 corneas studied to see if the presence of diabetes (type 1 or 2) in the donor led to reduction levels different from those of corneas originating from nondiabetic donors. RESULTS: The incidence was evaluated at between 0.4% and 3% of corneas sampled, and the associated risk factor was between 0.8% and 6% of grafted corneas. The occurrence of major losses was independent of donor age and was independent of the person who did the retrieval. The occurrence of major losses was independent of geographical origin. We tested our media for endotoxin before use and found levels from 0.22 to 3.9 UI/mL. We verified the absence of a chronological relationship between the batches of media used in the bank and the number of major losses observed, showing that the pyrogenicity limit was independent of cytotoxicity limits. Data analysis showed no difference in reduction levels between diabetic and nondiabetic donors (P < 0.05). Results on the detection of HSV-1 by PCR on the storage media were all negative, and these results agree with the anatomopathologic examinations that showed no signs of viral infection. CONCLUSION: Total endothelial losses amounted to 1.4%/yr. Without the double endothelial counts, we would have had 29 primary graft rejections over that period. During storage, this loss has not been linked to a specific cause, but risk factors such as traumatic death, herpes infections, and badly controlled endotoxin levels should be considered when taking preventative actions. For the moment, a second endothelial count before grafting should be carried out, because all these problem grafts conformed to grafting criteria after the first count. The possibility of carrying out this second count is one of the recognized advantages of storage in organ culture.PURPOSE: The aim of this study was to show that major losses can still occur on corneas judged suitable for grafting at the first count. In addition, we studied the frequency of these losses on 1992 corneas over a period of 4 years to evaluate the risk incurred. METHODS: We evaluated the incidence of these major losses and the associated risk factors. An Ishigawa diagram was created with the Cornea Bank team and the ophthalmologists involved in organ retrieval. Endothelial losses caused by bacterial or fungicidal contamination were excluded from the study. For the 29 corneas that suffered major losses, we analyzed the donor files for donor age, clinical file, geographical origins of the corneas, the person who did the retrieval, the length of time the cornea was stored, the data resulting from examining the endothelium at the bank by optical microscope, and the method used for sterilizing the material used. Specific analyses in cases of major loss of endothelial content: anatomopathologic examination of the corneas and search for the herpes simplex virus (HSV; type 1 or 2) by polymerase chain reaction (PCR). We carried out a statistical analysis using a chi(2) test on the 1992 corneas studied to see if the presence of diabetes (type 1 or 2) in the donor led to reduction levels different from those of corneas originating from nondiabetic donors. RESULTS: The incidence was evaluated at between 0.4% and 3% of corneas sampled, and the associated risk factor was between 0.8% and 6% of grafted corneas. The occurrence of major losses was independent of donor age and was independent of the person who did the retrieval. The occurrence of major losses was independent of geographical origin. We tested our media for endotoxin before use and found levels from 0.22 to 3.9 UI/mL. We verified the absence of a chronological relationship between the batches of media used in the bank and the number of major losses observed, showing that the pyrogenicity limit was independent of cytotoxicity limits. Data analysis showed no difference in reduction levels between diabetic and nondiabetic donors (P < 0.05). Results on the detection of HSV-1 by PCR on the storage media were all negative, and these results agree with the anatomopathologic examinations that showed no signs of viral infection. CONCLUSION: Total endothelial losses amounted to 1.4%/yr. Without the double endothelial counts, we would have had 29 primary graft rejections over that period. During storage, this loss has not been linked to a specific cause, but risk factors such as traumatic death, herpes infections, and badly controlled endotoxin levels should be considered when taking preventative actions. For the moment, a second endothelial count before grafting should be carried out, because all these problem grafts conformed to grafting criteria after the first count. The possibility of carrying out this second count is one of the recognized advantages of storage in organ culture

Contact guidance enhances the quality of a tissue engineered corneal stroma

International audienceCorneal stroma is a very complex structure, composed of 200 lamellae of oriented collagen fibers. This highly complex nature of cornea is known to be important for its transparency and mechanical integrity. Thus, an artificial cornea design has to take into account this complex structure. In this study, behavior of human corneal keratocytes on collagen films patterned with parallel channels was investigated. Keratocytes proliferated well on films and reached confluency after 7 days in the incubation medium. Nearly all of the cells responded to the patterns and were aligned in contrast to the cells on unpatterned surfaces. Collagen type I and keratan sulfate secreted by keratocytes on patterned films appeared to be aligned in the direction of the patterns. The films showed an intermediate degradation over the course of a month. On the whole, transparency of the films increased with degradation and decreased by the presence of the cells. The decrease was, however, low and transparency level was maintained on the patterned films while on the unpatterned films a sharp decrease in transparency was followed by an improvement. This was due to the more organized distribution of cells and the oriented secretion of extracellular matrix molecules on patterned collagen films. Thus, these results suggest that application of contact guidance in cornea tissue engineering may facilitate the remodeling process, hence decrease the rehabilitation period.Corneal stroma is a very complex structure, composed of 200 lamellae of oriented collagen fibers. This highly complex nature of cornea is known to be important for its transparency and mechanical integrity. Thus, an artificial cornea design has to take into account this complex structure. In this study, behavior of human corneal keratocytes on collagen films patterned with parallel channels was investigated. Keratocytes proliferated well on films and reached confluency after 7 days in the incubation medium. Nearly all of the cells responded to the patterns and were aligned in contrast to the cells on unpatterned surfaces. Collagen type I and keratan sulfate secreted by keratocytes on patterned films appeared to be aligned in the direction of the patterns. The films showed an intermediate degradation over the course of a month. On the whole, transparency of the films increased with degradation and decreased by the presence of the cells. The decrease was, however, low and transparency level was maintained on the patterned films while on the unpatterned films a sharp decrease in transparency was followed by an improvement. This was due to the more organized distribution of cells and the oriented secretion of extracellular matrix molecules on patterned collagen films. Thus, these results suggest that application of contact guidance in cornea tissue engineering may facilitate the remodeling process, hence decrease the rehabilitation period

Reconstructed corneas: effect of three-dimensional culture, epithelium, and tetracycline hydrochloride on newly synthesized extracellular matrix.

International audiencePURPOSE: To evaluate the influence of the 3-dimensional collagen-glycosaminogycan-chitosan (CGC 3D) scaffold, epithelialization, and the addition of tetracycline hydrochloride on the ultrastructural organization, measured by the diameter and spacing of newly synthesized collagen I fibrils. METHODS: Little is known about the role of interactions between epithelial cells and fibroblasts in controlling the extracellular matrix of the cornea. We developed a hemicornea from a CGC 3D matrix cocultured with keratocytes and human epithelial cells. The keratocytes colonized this substrate, proliferated, and synthesized the extracellular matrix, reproducing a living stroma equivalent. RESULTS: Without a 3D scaffold, the collagen fibrils produced had an average diameter that was 42.7 nm and sigma = 16.9 nm. In the CGC 3D scaffold, the fibrils had an average diameter of 33.4 nm, with little dispersion (sigma = 6.7 nm), suggesting a greater regulation. The epithelium permitted a significant reduction in fibril diameter and interfibrillar spacing. Tetracycline hydrochloride had no effect on spacing but did have a significant effect on fibril diameter. We found positive interactions between the epithelium and tetracycline hydrochloride on the regulation of collagen fibrils but not on spacing. The presence of epithelium led to the increased formation of collagens I and V in the subepithelial area of the newly formed matrix. Type VI collagen was localized around the keratocytes throughout the matrix. CONCLUSIONS: Epithelialization and the 3D scaffold had a great influence on the diameter of collagen I fibrils.PURPOSE: To evaluate the influence of the 3-dimensional collagen-glycosaminogycan-chitosan (CGC 3D) scaffold, epithelialization, and the addition of tetracycline hydrochloride on the ultrastructural organization, measured by the diameter and spacing of newly synthesized collagen I fibrils. METHODS: Little is known about the role of interactions between epithelial cells and fibroblasts in controlling the extracellular matrix of the cornea. We developed a hemicornea from a CGC 3D matrix cocultured with keratocytes and human epithelial cells. The keratocytes colonized this substrate, proliferated, and synthesized the extracellular matrix, reproducing a living stroma equivalent. RESULTS: Without a 3D scaffold, the collagen fibrils produced had an average diameter that was 42.7 nm and sigma = 16.9 nm. In the CGC 3D scaffold, the fibrils had an average diameter of 33.4 nm, with little dispersion (sigma = 6.7 nm), suggesting a greater regulation. The epithelium permitted a significant reduction in fibril diameter and interfibrillar spacing. Tetracycline hydrochloride had no effect on spacing but did have a significant effect on fibril diameter. We found positive interactions between the epithelium and tetracycline hydrochloride on the regulation of collagen fibrils but not on spacing. The presence of epithelium led to the increased formation of collagens I and V in the subepithelial area of the newly formed matrix. Type VI collagen was localized around the keratocytes throughout the matrix. CONCLUSIONS: Epithelialization and the 3D scaffold had a great influence on the diameter of collagen I fibrils