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Papers by Ramón Diaz
Journal of Clinical Investigation, 1995
Graft arteriopathy, a leading cause of cardiac allograft failure, is associated with increased in... more Graft arteriopathy, a leading cause of cardiac allograft failure, is associated with increased intimal smooth muscle cells, inflammatory cells, and accumulation of extracellular matrix. We hypothesized that cellular fibronectin plays a pivotal role in the progression of the allograft arteriopathy by directing the transendothelial trafficking of inflammatory cells through interaction of the connecting segment-i (CS1) motif with the very late antigen-4 (VLA-4) integrin, and tested this in vivo using a blocking peptide. Cholesterolfed rabbits underwent heterotopic cardiac transplantation without immunosuppression. The treatment group (n = 7) received a synthetic CS1 peptide (1 mg/kg per d, subcutaneously), and the controls (n = 7) received an inactive peptide (1 mg/kg per d, subcutaneously). At 7-8 d after transplantation, hearts were harvested and sectioned for morphometric analysis and immunohistochemical studies. We observed a > 50% decrease in the incidence (P < 0.001) and severity (P < 0.001) of donor coronary artery intimal thickening in the CS1-treated compared with the control group. These findings correlated with reduced infiltration of T cells (P < 0.05), a trend toward decreased expression of adhesion molecules (P < 0.06), and less accumulation of fibronectin (P < 0.03). Our data suggest that the VLA-4-fibronectin interaction is critical to the progression of the allograft arteriopathy by perpetuating the immune-inflammatory response in the vessel wall. (J. Clin. Invest 1995Invest . 95:2601Invest -2610
Journal of Clinical Investigation, 1995
A study was performed to evaluate the previously described PCR (C. Romero, C. Gamazo, M. Pardo, a... more A study was performed to evaluate the previously described PCR (C. Romero, C. Gamazo, M. Pardo, and I. López-Goñi, J. Clin. Microbiol. 33:615-617, 1995) for the diagnosis of brucellosis in dairy cattle. Milk samples from 56 Brucella milk culture-positive cattle and from 37 cattle from Brucella-free herds were examined for Brucella DNA by PCR and for specific antibodies by an indirect enzyme-linked immunosorbent assay (ELISA). The specificities of both tests were 100% when testing the milk samples from Brucella-free cattle. The milk samples from 49 infected cattle were positive by PCR (87.5% sensitivity), and 55 were positive by ELISA (98.2% sensitivity). A PCR-positive sample was negative by ELISA, and 7 ELISA-positive samples were PCR negative, yielding an observed proportion of agreement of 0.91 for the two tests. Although the results suggest that ELISA is a better screening test than PCR, the combined sensitivity of the two assays was 100%, and their simultaneous application could be more useful than one test alone for a rapid screening of brucellosis in dairy cattle.
Veterinary Microbiology, 1987
International Journal of Systematic Bacteriology, 1998
Ochrobactrum intermedium sp. nov., a new species with a closer relationship to Brucella SPP.
En este artículo se ilustra cómo la argumentación en el contexto de la educación en ciencias, es ... more En este artículo se ilustra cómo la argumentación en el contexto de la educación en ciencias, es objeto de estudio de diferentes investigaciones sobre comunicación, aprendizaje y desarrollo de procesos de pensamiento. Teniendo en cuenta los propósitos actuales de la educación en ciencias, es importante considerar la argumentación, como una línea de investigación actual y altamente promisoria en este campo de saber. De la misma manera, se hace necesario el considerar las contribuciones de la propuesta filosófica de Stephen Toulmin y el valor de estas para la innovación en la enseñanza y el aprendizaje de las ciencias en el siglo XXI. Asimismo, se muestra la relación que existe entre el constructivismo social y la argumentación, el cual considera el aprendizaje como un proceso de construcción de conocimiento. De igual manera, se presentan planteamientos sobre cómo el argumentar promueve logros como el conocimiento de ciencias naturales y el desarrollo de competencias ciudadanas. Por último, se incluyen algunos principios de diseño para promover argumentación.
Journal of Clinical Investigation, 1995
Graft arteriopathy, a leading cause of cardiac allograft failure, is associated with increased in... more Graft arteriopathy, a leading cause of cardiac allograft failure, is associated with increased intimal smooth muscle cells, inflammatory cells, and accumulation of extracellular matrix. We hypothesized that cellular fibronectin plays a pivotal role in the progression of the allograft arteriopathy by directing the transendothelial trafficking of inflammatory cells through interaction of the connecting segment-i (CS1) motif with the very late antigen-4 (VLA-4) integrin, and tested this in vivo using a blocking peptide. Cholesterolfed rabbits underwent heterotopic cardiac transplantation without immunosuppression. The treatment group (n = 7) received a synthetic CS1 peptide (1 mg/kg per d, subcutaneously), and the controls (n = 7) received an inactive peptide (1 mg/kg per d, subcutaneously). At 7-8 d after transplantation, hearts were harvested and sectioned for morphometric analysis and immunohistochemical studies. We observed a > 50% decrease in the incidence (P < 0.001) and severity (P < 0.001) of donor coronary artery intimal thickening in the CS1-treated compared with the control group. These findings correlated with reduced infiltration of T cells (P < 0.05), a trend toward decreased expression of adhesion molecules (P < 0.06), and less accumulation of fibronectin (P < 0.03). Our data suggest that the VLA-4-fibronectin interaction is critical to the progression of the allograft arteriopathy by perpetuating the immune-inflammatory response in the vessel wall. (J. Clin. Invest 1995Invest . 95:2601Invest -2610
Journal of Clinical Investigation, 1995
A study was performed to evaluate the previously described PCR (C. Romero, C. Gamazo, M. Pardo, a... more A study was performed to evaluate the previously described PCR (C. Romero, C. Gamazo, M. Pardo, and I. López-Goñi, J. Clin. Microbiol. 33:615-617, 1995) for the diagnosis of brucellosis in dairy cattle. Milk samples from 56 Brucella milk culture-positive cattle and from 37 cattle from Brucella-free herds were examined for Brucella DNA by PCR and for specific antibodies by an indirect enzyme-linked immunosorbent assay (ELISA). The specificities of both tests were 100% when testing the milk samples from Brucella-free cattle. The milk samples from 49 infected cattle were positive by PCR (87.5% sensitivity), and 55 were positive by ELISA (98.2% sensitivity). A PCR-positive sample was negative by ELISA, and 7 ELISA-positive samples were PCR negative, yielding an observed proportion of agreement of 0.91 for the two tests. Although the results suggest that ELISA is a better screening test than PCR, the combined sensitivity of the two assays was 100%, and their simultaneous application could be more useful than one test alone for a rapid screening of brucellosis in dairy cattle.
Veterinary Microbiology, 1987
International Journal of Systematic Bacteriology, 1998
Ochrobactrum intermedium sp. nov., a new species with a closer relationship to Brucella SPP.
En este artículo se ilustra cómo la argumentación en el contexto de la educación en ciencias, es ... more En este artículo se ilustra cómo la argumentación en el contexto de la educación en ciencias, es objeto de estudio de diferentes investigaciones sobre comunicación, aprendizaje y desarrollo de procesos de pensamiento. Teniendo en cuenta los propósitos actuales de la educación en ciencias, es importante considerar la argumentación, como una línea de investigación actual y altamente promisoria en este campo de saber. De la misma manera, se hace necesario el considerar las contribuciones de la propuesta filosófica de Stephen Toulmin y el valor de estas para la innovación en la enseñanza y el aprendizaje de las ciencias en el siglo XXI. Asimismo, se muestra la relación que existe entre el constructivismo social y la argumentación, el cual considera el aprendizaje como un proceso de construcción de conocimiento. De igual manera, se presentan planteamientos sobre cómo el argumentar promueve logros como el conocimiento de ciencias naturales y el desarrollo de competencias ciudadanas. Por último, se incluyen algunos principios de diseño para promover argumentación.