Cardiac metastases

We report a case of esophageal cancer with symptomatic metastases to the heart; the patient was treated with short-course radiotherapy with good symptomatic relief. We reviewed the current literature regarding the epidemiology, clinical presentation, diagnostic tools, treatment modalities, and the prognosis of cardiac metastases. In this report we summarize the most recent autopsy studies (published between 1975 and 2007), in which we found an autopsy incidence of cardiac metastases of 2.3% among the general population, while the incidence among autopsies of cancer patients was 7.1%. Therefore, we share the opinion with others that there has been an increase in the incidence of cardiac metastases among cancer patients diagnosed after 1970, in comparison with the reported incidences in older series before 1970 (7.1% vs 3.8%; Kruskal-Wallis rank test; P = 0.039). Special attention was given to the role of radiotherapy in the management of cardiac metastases

Effect of Strain Magnitude on the Tissue Properties of Engineered Cardiovascular Constructs

Mechanical loading is a powerful regulator of tissue properties in engineered cardiovascular tissues. To ultimately regulate the biochemical processes, it is essential to quantify the effect of mechanical loading on the properties of engineered cardiovascular constructs. In this study the Flexercell FX-4000T (Flexcell Int. Corp., USA) straining system was modified to simultaneously apply various strain magnitudes to individual samples during one experiment. In addition, porous polyglycolic acid (PGA) scaffolds, coated with poly-4-hydroxybutyrate (P4HB), were partially embedded in a silicone layer to allow long-term uniaxial cyclic mechanical straining of cardiovascular engineered constructs. The constructs were subjected to two different strain magnitudes and showed differences in biochemical properties, mechanical properties and organization of the microstructure compared to the unstrained constructs. The results suggest that when the tissues are exposed to prolonged mechanical stimulation, the production of collagen with a higher fraction of crosslinks is induced. However, straining with a large strain magnitude resulted in a negative effect on the mechanical properties of the tissue. In addition, dynamic straining induced a different alignment of cells and collagen in the superficial layers compared to the deeper layers of the construct. The presented model system can be used to systematically optimize culture protocols for engineered cardiovascular tissues

La trigonometría como herramienta para medir nuestro entorno

En esta experiencia de aula se presenta el trabajo de un grupo de estudiantes de grado décimo que realizaron una actividad en la clase de trigonometría en la que aplicaron conceptos trigonométricos para calcular las medidas de las instalaciones de la institución educativa a la cual pertenecen. El objetivo es mostrar un ejemplo de cómo se puede generar un ambiente de aprendizaje en el que los estudiantes puedan elaborar significados de objetos matemáticos como lo son las razones trigonométricas mediante una labor que permita la aplicación fundamental de la trigonometría realizando mediciones indirectas

Microstructural analysis of deformation-induced hypoxic damage in skeletal muscle

Deep pressure ulcers are caused by sustained mechanical loading and involve skeletal muscle tissue injury. The exact underlying mechanisms are unclear, and the prevalence is high. Our hypothesis is that the aetiology is dominated by cellular deformation (Bouten et al. in Ann Biomed Eng 29:153–63, 2001; Breuls et al. in Ann Biomed Eng 31:1357–364, 2003; Stekelenburg et al. in J App Physiol 100(6):1946–954, 2006) and deformation-induced ischaemia. The experimental observation that mechanical compression induced a pattern of interspersed healthy and dead cells in skeletal muscle (Stekelenburg et al. in J App Physiol 100(6):1946–954, 2006) strongly suggests to take into account the muscle microstructure in studying damage development. The present paper describes a computational model for deformation-induced hypoxic damage in skeletal muscle tissue. Dead cells stop consuming oxygen and are assumed to decrease in stiffness due to loss of structure. The questions addressed are if these two consequences of cell death influence the development of cell injury in the remaining cells. The results show that weakening of dead cells indeed affects the damage accumulation in other cells. Further, the fact that cells stop consuming oxygen after they have died, delays cell death of other cells