Academically Oriented Activity Breaks for First-Grade Chilean Students: Development and Pilot Testing Effectiveness.

We developed and pilot tested the effectiveness of a physically active academic program, Active Breaks (AB), whose objective is to increase school time moderate/vigorous physical activity (MVPA) among first graders, through daily 15-minute bouts of MVPA, at the beginning of the first lesson. Initially, 240 cards including one game each were developed and tested in first-grade students from 16 schools in Santiago. Trained observers and school teachers assessed the time, ease, and feasibility of implementation for each card. Barriers and facilitators to implementation were obtained from semistructured interviews to 14 teachers (out of 16). In eight schools (n = 556 students), we compared school time MVPA (with accelerometers) at baseline and follow-up, using test of proportions. One-hundred and twenty cards (games) complied with all aspects. AB were implemented 50% of the time with a duration of 14 minutes (SD = 5). More than 90% of the time, teachers felt competent to conduct AB, and children understood the instructions and enjoyed the activity. The main facilitators included teachers liking physical activity and considering it important, support of principal and school staff, and conducting AB inside the classroom. Barriers included teacher's workload and having to conduct AB during the first lesson. During the 4-month period of implementation, MVPA increased by 1.5 and 1.2 percentage points in boys and girls, respectively. The set of 120 cards is easy and feasible to implement. Moreover, preliminary results suggest they could be effective in increasing MVPA during school time, although studies with longer follow-ups are needed to assess the validity of these findings.

Glucose deprivation causes oxidative stress and stimulates aggresome formation and autophagy in cultured cardiac myocytes.

Aggresomes are dynamic structures formed when the ubiquitin-proteasome system is overwhelmed with aggregation-prone proteins. In this process, small protein aggregates are actively transported towards the microtubule-organizing center. A functional role for autophagy in the clearance of aggresomes has also been proposed. In the present work we investigated the molecular mechanisms involved on aggresome formation in cultured rat cardiac myocytes exposed to glucose deprivation. Confocal microscopy showed that small aggregates of polyubiquitinated proteins were formed in cells exposed to glucose deprivation for 6 h. However, at longer times (18 h), aggregates formed large perinuclear inclusions (aggresomes) which colocalized with gamma-tubulin (a microtubule-organizing center marker) and Hsp70. The microtubule disrupting agent vinblastine prevented the formation of these inclusions. Both small aggregates and aggresomes colocalized with autophagy markers such as GFP-LC3 and Rab24. Glucose deprivation stimulates reactive oxygen species (ROS) production and decreases intracellular glutathione levels. ROS inhibition by N-acetylcysteine or by the adenoviral overexpression of catalase or superoxide dismutase disrupted aggresome formation and autophagy induced by glucose deprivation. In conclusion, glucose deprivation induces oxidative stress which is associated with aggresome formation and activation of autophagy in cultured cardiac myocytes.

Autofagia del cardiomiocito: ¿un nuevo mecanismo de adaptación al estrés o de muerte celular? / Cardiomyocyte autophagy: a new adaptative mechanism to stress or new form of cell death?

Históricamente, la apoptosis y la necrosis han sido consideradas como las dos formas fundamentales de muerte celular. Sin embargo, evidencias recientes sugieren que la muerte celular programada no está confinada sólo a la apoptosis sino que las células disponen de distintos mecanismos de autodestrucción, entre los que se cuenta la autofagia. Esta última se define como un proceso dinámico y programado que procede con el secuestro de proteínas citoplasmáticas y organelos enteros dentro de vacuolas de doble membrana, que se contactan y se fusionan con los lisosomas, formando los autolisosomas. Los elementos capturados en las vacuolas son degradados por proteasas lisosomales y removidos de la célula por exocitosis. La autofagia se describió inicialmente como un proceso fisiológico clave para la sobrevida celular en respuesta al estrés derivado de la privación de nutrientes. Además, la autofagia también se ha observado en algunas patologías cardiovasculares, especialmente aquellas asociadas a procesos de isquemia/reperfusión. En esta revisión se sintetiza el conocimiento actual de la autofagia, sus implicancias y proyecciones en el área cardiovascular.

Cross-reactivity of human lupus anti-DNA antibodies with alpha-actinin and nephritogenic potential.

OBJECTIVE: Cross-reactivity with kidney antigens is believed to be a critical determinant in the renal pathogenicity of anti-double-stranded DNA (anti-dsDNA) antibodies. Murine nephritogenic anti-dsDNA antibodies have been shown to cross-react with alpha-actinin, and anti-alpha-actinin antibodies have been found to be deposited in the kidneys of lupus mice with active nephritis. Furthermore, in humans with systemic lupus erythematosus (SLE), it has been found that a greater proportion of polyclonal IgG anti-dsDNA antibodies from patients with renal involvement bind to alpha-actinin than do those from patients without renal disease. We undertook this study to substantiate a direct link between cross-reactive anti-dsDNA/anti-alpha-actinin antibodies and the pathogenesis of lupus nephritis in humans. METHODS: A panel of 10 anti-dsDNA and/or anti-alpha-actinin antibodies was generated by Epstein-Barr virus transformation of lymphocytes from patients with SLE and was extensively characterized. Antibody binding was studied by enzyme-linked immunosorbent assay and Western blotting. Antibody potential for pathogenicity was assessed by measuring binding to isolated glomeruli and mesangial cells and by evaluation of histologic features of the kidney following injection in vivo. RESULTS: All anti-dsDNA antibodies isolated also bound alpha-actinin. Cross-reactive antibodies bound to mesangial cells and to isolated glomeruli ex vivo. Binding to glomeruli was not inhibited by DNase treatment, but could be abrogated by alpha-actinin. Furthermore, histopathologic abnormalities seen in mice injected intraperitoneally with a cross-reactive cell line included fusion of podocyte foot processes and subepithelial and subendothelial deposition. CONCLUSION: These studies provide strong support for the hypothesis that alpha-actinin is a major cross-reactive target for anti-dsDNA antibodies in SLE patients. Cross-reactive anti-dsDNA/anti-alpha-actinin antibodies from SLE patients are pathogenic and may contribute to the kidney lesions in lupus nephritis.

Differential effects of interleukin-4 in peptide induced autoimmunity.

BALB/c mice immunized with multimeric DWEYSVWLSN develop IgG1 anti-DNA antibodies and glomerular immunoglobulin deposits, leading us to investigate the role of IL-4 in this model of antigen induced lupus. Splenocytes from DWEYSVWLSN immunized mice secreted IL-4 but not gamma-interferon. Following peptide immunization, IgG1 anti-peptide and anti-DNA antibodies were significantly higher in IL-4 wild type mice, while IgM and IgG3 anti-DNA levels were significantly higher in IL-4 knockout mice. Titers of IgG anti-laminin and anti-histone, but not anti-Sm/RNP and anti-cardiolipin antibodies, were significantly higher in the IL-4 wild type group. Glomerular immunoglobulin deposition was substantially decreased in IL-4 knockout mice. We conclude that while IL-4 does not materially affect the generation of some autoantibody responses associated with peptide induced autoimmunity, IL-4 deficiency inhibits kidney immunoglobulin deposition. The effect of IL-4 on humoral autoimmunity in lupus is complex, and is dependent on genetic background, the antigenic trigger and stage of disease.