Lactate stress test in the diagnosis of mitochondrial myopathy.

The aim of the study was to determine the sensitivity and specificity of the lactate stress test in the detection of mitochondrial myopathies. Thirty one healthy subjects, 10 patients with non-mitochondrial myopathy and 26 patients with mitochondrial myopathy underwent lactate stress testing at a standardized workload of 30 W during 15 min on a bicycle ergometer. Lactate was determined before the exercise (R1), 5, 10, 15 min after starting the exercise (S5, S10, S15) and 15 min after finishing the exercise (R2).

Targeted inactivation of plectin reveals essential function in maintaining the integrity of skin, muscle, and heart cytoarchitecture.

Previous studies suggest that plectin, a versatile cytoskeletal linker protein, has an important role in maintaining the structural integrity of diverse cells and tissues. To establish plectin's function in a living organism, we have disrupted its gene in mice. Plectin (-/-) mice died 2-3 days after birth exhibiting skin blistering caused by degeneration of keratinocytes.

Dystrophin expression in heterozygous mdx/+ mice indicates imprinting of X chromosome inactivation by parent-of-origin-, tissue-, strain- and position-dependent factors.

Inactivation of one X chromosome (X inactivation) in female mammals results in dosage compensation of X-chromosomally encoded genes between sexes. In the embryo proper of most mammals X inactivation is thought to occur at random with respect to the parental origin of the X chromosome. We determined on the cellular level the expression of the X-chromosomally encoded protein dystrophin in skeletal and cardiac muscle of female mice heterozygous for a null mutation of the dystrophin gene (mdx/+).

[Lactate determination at rest and during bicycle ergometry in healthy probands and in patients with mitochondrial myopathies].

Measuring lactate during moderate exercise is a useful tool in the diagnosis of mitochondrial disorders. It was the aim of this study, to develop reference limits for lactate at rest, during exercise and after the exercise. We investigated 18 healthy subjects and 6 patients with a mitochondrial disorder.