Muscle oxidative capacity and work performance after training under local leg ischemia

Healthy young men executed supine one-legged cycle training four times per week for 4 wk with legs and the cycle ergometer inside a pressure chamber, the opening of which was sealed by a rubber membrane at the level of the crotch. Each training session started by training one leg under ischemic conditions induced by increased chamber pressure (50 mmHg) at the highest intensity tolerable for 45 min. Then the other leg was trained with the same power profile but normal atmospheric chamber pressure. Before and after the training period, both legs executed one-legged exercise tests under both normal and increased chamber pressure and muscle biopsies were taken from the vastus lateralis. Ischemic training increased performance more than normal training, the difference being greater for exercise executed under ischemic conditions. The difference in performance increase between the legs was paralleled by a greater muscle citrate synthase activity in the ischemically than in the normally trained leg.     

Immunogenicity of human embryonic stem cells

Human embryonic stem cells (HESC) are pluripotent stem cells isolated from the inner cell mass of human blastocysts. With the first successful culturing of HESC, a new era of regenerative medicine was born. HESC can differentiate into almost any cell type and, in the future, might replace solid organ transplantation and even be used to treat progressive degenerative diseases such as Parkinson’s disease. Although this sounds promising, certain obstacles remain with regard to their clinical use, such as culturing HESC under well-defined conditions without exposure to animal proteins, the risk of teratoma development and finally the avoidance of immune rejection. In this review, we discuss the immunological properties of HESC and various strategic solutions to circumvent immune rejection, such as stem cell banking, somatic cell nuclear transfer and the induction of tolerance by co-stimulation blockade and mixed chimerism.     

Die natürliche Auslese im Dienste der Rotkleezüchtung

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