Value of the First Post-Transplant Biopsy for Predicting Long-Term Cardiac Allograft Vasculopathy (CAV) and Graft Failure in Heart Transplant Patients

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the principal cause of long-term graft failure following heart transplantation. Early identification of patients at risk of CAV is essential to target invasive follow-up procedures more effectively and to establish appropriate therapies. We evaluated the prognostic value of the first heart biopsy (median: 9 days post-transplant) versus all biopsies obtained within the first three months for the prediction of CAV and graft failure due to CAV. METHODS AND FINDINGS: In a prospective cohort study, we developed multivariate regression models evaluating markers of atherothrombosis (fibrin, antithrombin and tissue plasminogen activator [tPA]) and endothelial activation (intercellular adhesion molecule-1) in serial biopsies obtained during the first three months post-transplantation from 172 patients (median follow-up = 6.3 years; min = 0.37 years, max = 16.3 years). Presence of fibrin was the dominant predictor in first-biopsy models (Odds Ratio [OR] for one- and 10-year graft failure due to CAV = 38.70, p = 0.002, 95% CI = 4.00-374.77; and 3.99, p = 0.005, 95% CI = 1.53-10.40) and loss of tPA was predominant in three-month models (OR for one- and 10-year graft failure due to CAV = 1.81, p = 0.025, 95% CI = 1.08-3.03; and 1.31, p = 0.001, 95% CI = 1.12-1.55). First-biopsy and three-month models had similar predictive and discriminative accuracy and were comparable in their capacities to correctly classify patient outcomes, with the exception of 10-year graft failure due to CAV in which the three-month model was more predictive. Both models had particularly high negative predictive values (e.g., First-biopsy vs. three-month models: 99% vs. 100% at 1-year and 96% vs. 95% at 10-years). CONCLUSIONS: Patients with absence of fibrin in the first biopsy and persistence of normal tPA in subsequent biopsies rarely develop CAV or graft failure during the next 10 years and potentially could be monitored less invasively. Presence of early risk markers in the transplanted heart may be secondary to ischemia/reperfusion injury, a potentially modifiable factor

Competencias de pensamiento científico y resolución de problemas de genética simulados computacionalmente. su contribución al aprendizaje de la Biología

Esta investigación se relaciona con las implicancias didácticas de la incorporación de las simulaciones computacionales a la enseñanza de la genética escolar. Específicamente, se identifican y caracterizan competencias de pensamiento científico (CPC) que desarrollan estudiantes de secundaria, al momento de enfrentarse a la resolución de problemas de genética simulados mediante un software. Los resultados indican que los estudiantes abordan los distintos problemas científicos a través de diversas competencias de pensamiento científico, con distintas frecuencia y tipología. Además, las vinculaciones conceptuales, establecidas son principalmente de tipo explicativo-causal, lo que aparentemente estaría condicionado por las orientaciones metodológicas y las finalidades teóricas del software utilizado

¿Qué es y cómo opera la evaluación en el aula de Química, según docentes en ejercicio? entre el discurso y la práctica

En esta investigación nos propusimos comprender las finalidades de las prácticas evaluativas de profesores de Química en ejercicio de Enseñanza Media, con el fin de entregar un aporte a la comunidad docente para desarrollar competencias de pensamiento científico. ¿qué y cuáles con las finalidades de las prácticas evaluativas de los profesores de Química en ejercicio?, ¿Cuáles son las concepciones teóricas sobre evaluación de aprendizajes en la clase de química? ¿Qué tipos de estrategias evaluativas e instrumentos utilizan los profesores de Química en ejercicio? La búsqueda de respuestas a estas preguntas a través de una investigación y su posterior análisis documentado entrega un aporte al conocimiento teórico, teniendo presente al proceso de evaluación como una herramienta al servicio del aprendizaje científico

Competencias de pensamiento científico y resolución de problemas de genética simulados computacionalmente. su contribución al aprendizaje de la Biología

Esta investigación se relaciona con las implicancias didácticas de la incorporación de las simulaciones computacionales a la enseñanza de la genética escolar. Específicamente, se identifican y caracterizan competencias de pensamiento científico (CPC) que desarrollan estudiantes de secundaria, al momento de enfrentarse a la resolución de problemas de genética simulados mediante un software. Los resultados indican que los estudiantes abordan los distintos problemas científicos a través de diversas competencias de pensamiento científico, con distintas frecuencia y tipología. Además, las vinculaciones conceptuales, establecidas son principalmente de tipo explicativo-causal, lo que aparentemente estaría condicionado por las orientaciones metodológicas y las finalidades teóricas del software utilizado

Resolución de problemas científicos escolares y promoción de competencias de pensamiento científico. ¿Qué piensan los docentes de química en ejercicio?

In the article the results of an investigation conducted within the framework of the project FONDECYT 1070795 are exposed. The aims of the research were to identify and characterize the representations and knowledge that teachers in service have, from an average level of education, with respect to the competences of scientific thought and problem solution, and the way in which both should be approached. With the use of an intentional sample of 133, teachers selected from a total of 117 who were incorporated to other phases of the research trough the administration of a questionnaire especially designed, was show the predominance of a very fragmented image, sometimes contradictory, about the solution of problems and about relation between competences of scientific thought; this representation incorporates aspects of great value for the formation of the competent students, and at the same time it includes other aspects that in no way favor this formation, according to the present assessments. It is remarkable that both competences for scientific thought and solution of problems are not constituted as a totality and coherent system in the thinking of the teachers who participated in the research. It should be pointed out that we found data that show an oscillating valuation of the subjective character of the problematic situations and the problem itself; these data show, as well, that teachers give a very important role to language. It is stated that teachers give an oscillating value to the fact that students must deal with theories. It should be noted too that their approaches to the algorithmic processes are very vague, and sometimes contradictory.En el artículo se exponen los resultados de una investigación realizada en el marco del proyecto FONDECYT 1070795, cuyo objetivo consistió en identificar y caracterizar las nociones que tienen los profesores de nivel medio respecto a las competencias de pensamiento científico y solución de problemas, y la manera en que ambos deben trabajarse en la enseñanza de la química. Con el empleo de una muestra intencional de 33 profesores, seleccionados de un total de 117 que se incorporaron a otras fases de la investigación y mediante la administración de un cuestionario especialmente diseñado, se logró poner de manifiesto que en ellos predomina una imagen fragmentada y a veces contradictoria de la solución de problemas y de las competencias de pensamiento científico; dicha representación incorpora aspectos de inestimable valor para la formación del estudiante competente, a la vez que incluye otros que en manera alguna favorecen dicha formación en correspondencia con las exigencias actuales. Es notable que competencias de pensamiento científico y solución de problemas no se constituyan como sistema totalmente coherente en la conceptualización de los profesores investigados. Como dato relevante, se constató la oscilante valoración del carácter subjetivo de las situaciones problémicas y los problemas; junto al papel importante que, en opinión de gran parte de los profesores, desempeña el lenguaje, se le otorga un valor oscilante al trabajo con la teoría por parte de los estudiantes; igualmente resulta difusa, y a veces contradictoria, su aproximación a los procesos de algoritmización

Failure of physiologic transformation of spiral arteries, endothelial and trophoblast cell activation, and acute atherosis in the basal plate of the placenta

BACKGROUND: Failure of physiologic transformation of spiral arteries has been reported in preeclampsia, fetal growth restriction, fetal death, and spontaneous preterm labor with intact or ruptured membranes. Spiral arteries with failure of physiologic transformation are prone to develop atherosclerotic-like lesions of atherosis. There are striking parallels between preeclampsia and atherosclerotic disease, and between lesions of atherosis and atherosclerosis. Endothelial activation, identified by intercellular adhesion molecule-1 expression, is present in atherosclerotic-like lesions of heart transplantation, and is considered a manifestation of rejection. Similarly, endothelial activation/dysfunction has been implicated in the pathophysiology of atherosclerosis and preeclampsia. Intercellular adhesion molecule-1-overexpressing-activated endothelial cells are more resistant to trophoblast displacement than nonactivated endothelium, and may contribute to shallow spiral artery trophoblastic invasion in obstetrical syndromes having failure of physiologic transformation. OBJECTIVE: We sought to determine whether failure of spiral artery physiologic transformation was associated with activation of interstitial extravillous trophoblasts and/or spiral artery endothelium and presence of acute atherosis in the placental basal plate. STUDY DESIGN: A cross-sectional study of 123 placentas (19-42 weeks' gestation) obtained from normal pregnancies (n = 22), preterm prelabor rupture of membranes (n = 26), preterm labor (n = 23), preeclampsia (n = 27), intrauterine fetal death (n = 15), and small for gestational age (n = 10) was performed. Failure of spiral artery physiologic transformation and presence of cell activation was determined using immunohistochemistry of placental basal plates containing a median of 4 (minimum: 1; maximum: 9) vessels per placenta. Endothelial/trophoblast cell activation was defined by the expression of intercellular adhesion molecule-1. Investigators examining microscopic sections were blinded to clinical diagnosis. Pairwise comparisons among placenta groups were performed with Fisher exact test and Wilcoxon rank sum test using a Bonferroni-adjusted level of significance (.025). RESULTS: We found that 87% (94/108) of placentas having spiral arteries with failure of physiologic transformation (actin-positive and cytokeratin-negative) in the basal plate, and 0% (0/15) of placentas having only spiral arteries with complete physiologic transformation (cytokeratin-positive and actin-negative), had arterial endothelial and/or interstitial extravillous trophoblasts reactive with the intercellular adhesion molecule-1 activation marker (P < .001). A significant correlation (R2 = 0.84) was found between expression of spiral artery endothelial and interstitial extravillous trophoblast intercellular adhesion molecule-1 (P < .001) in activated placentas. Lesions of atherosis were found in 31.9% (30/94) of placentas with complete and/or partial failure of physiologic transformation of spiral arteries that were intercellular adhesion molecule-1-positive, in none of the 14 placentas with failure of physiologic transformation that were intercellular adhesion molecule-1-negative, and in none of the 15 placentas with complete spiral artery physiologic transformation without failure (P = .001). All placentas (30/30, 100%) with atherosis were identified in placentas having concomitant spiral artery endothelial and interstitial extravillous trophoblast activation. CONCLUSION: Failure of spiral artery physiologic transformation in the placental basal plate is associated with interstitial extravillous trophoblast and arterial endothelial activation along with increased frequency of spiral artery atherosis. These findings may be used to improve the characterization of different disorders of the placental bed such as in refining the existing tools for the early prediction of risk for preterm, preeclamptic, and other abnormal pregnancies

Resolución de problemas científicos escolares y promoción de competencias de pensamiento científico. ¿Qué piensan los docentes de química en ejercicio?

En el artículo se exponen los resultados de una investigación realizada en el marco del proyecto FONDECYT 1070795, cuyo objetivo consistió en identificar y caracterizar las nociones que tienen los profesores de nivel medio respecto a las competencias de pensamiento científico y solución de problemas, y la manera en que ambos deben trabajarse en la enseñanza de la química. Con el empleo de una muestra intencional de 33 profesores, seleccionados de un total de 117 que se incorporaron a otras fases de la investigación y mediante la administración de un cuestionario especialmente diseñado, se logró poner de manifiesto que en ellos predomina una imagen fragmentada y a veces contradictoria de la solución de problemas y de las competencias de pensamiento científico; dicha representación incorpora aspectos de inestimable valor para la formación del estudiante competente, a la vez que incluye otros que en manera alguna favorecen dicha formación en correspondencia con las exigencias actuales. Es notable que competencias de pensamiento científico y solución de problemas no se constituyan como sistema totalmente coherente en la conceptualización de los profesores investigados. Como dato relevante, se constató la oscilante valoración del carácter subjetivo de las situaciones problémicas y los problemas; junto al papel importante que, en opinión de gran parte de los profesores, desempeña el lenguaje, se le otorga un valor oscilante al trabajo con la teoría por parte de los estudiantes; igualmente resulta difusa, y a veces contradictoria, su aproximación a los procesos de algoritmización.In the article the results of an investigation conducted within the framework of the project FONDECYT 1070795 are exposed. The aims of the research were to identify and characterize the representations and knowledge that teachers in service have, from an average level of education, with respect to the competences of scientific thought and problem solution, and the way in which both should be approached. With the use of an intentional sample of 133, teachers selected from a total of 117 who were incorporated to other phases of the research trough the administration of a questionnaire especially designed, was show the predominance of a very fragmented image, sometimes contradictory, about the solution of problems and about relation between competences of scientific thought; this representation incorporates aspects of great value for the formation of the competent students, and at the same time it includes other aspects that in no way favor this formation, according to the present assessments. It is remarkable that both competences for scientific thought and solution of problems are not constituted as a totality and coherent system in the thinking of the teachers who participated in the research. It should be pointed out that we found data that show an oscillating valuation of the subjective character of the problematic situations and the problem itself; these data show, as well, that teachers give a very important role to language. It is stated that teachers give an oscillating value to the fact that students must deal with theories. It should be noted too that their approaches to the algorithmic processes are very vague, and sometimes contradictory