The cellular components of the satellite cell niche participate in the regulation of skeletal muscle regeneration. Beside myogenic cells at different developmental stages, this niche is formed by cells of the immune system, the interstitial connective tissue and the vascular ystem. Unambiguous determination of the origin of these cell types could contribute to optimization of the cell-based therapy of skeletal muscle disorders. In our work, we intravenously transplanted mouse GFP+ unseparated bone marrow cells into whole-body lethally irradiated immunocom-petent mice four weeks before cardiotoxin-induced injury of the recipients’ skeletal muscles. Seven and 28 days after the toxin injection, the injured regenerating and contralateral intact muscles were examined for identification of GFP+ bone marrow-derived cells by direct fluorescence, protein immunohistochemistry and immunogold transmission electron microscopy. In both the intact and injured muscles, GFP positivity was determined in immune cells, mainly in macrophages, and in interstitial spindle-shaped cells. Moreover, in the injured muscles, rare GFP+ endothelial cells of the blood vessels and newly formed myotubes and muscle fibres were present. Our results confirmed the ability of bone marrow-derived cells to contribute to the cellular component of the satellite cell niche in the intact and regenerating skeletal muscle. These cells originated not only from haematopoietic stem cells, but obviously also from other stem or progenitor cells residing in the bone marrow, such as multipotent mesenchymal stromal cells and endothelial progenitors. and Corresponding author: Dana Čížková
Taurine, a sulphur - containing amino acid, has been termed
a functional nutrient. Its synthetic form is a common ingredient
in supplements and energy drinks. There is no information
concerning taurine impact on bone microstructure after
prolonged supplemental use. Also, differences in bone
parameters of mice following taurine exposure are unknown. In
this study, a detailed microstructure of compact and trabecular
bone tissues of mice subchronically exposed to taurine was
determined. Animals (n=12) were segregated into three groups:
E1 group – mice received 20 mg/kg b.w. of taurine per day
during 8 weeks; E2 group – mice were fed by taurine at a dose
of 40 mg/kg b.w. for 8 weeks and a control (C) group. Decreased
density of secondary osteons, increased sizes of primary osteon's
vascular canals (P<0.05) were observed in taurine – treated
animals. Cortical bone thickness, trabecular thickness were
decreased (P<0.05) in E1 group, and relative volume of
trabecular bone was lower (P<0.05) in E2 group as compared to
C group. According to our results, prolonged taurine exposure at
the doses used in this study can negatively affect both compact
and trabecular bone tissues microstructure.
Information retrieval systems depend on Boolean queries. Proposed evolution of Boolean queries should increase the performance of the information retrieval system. Information retrieval systems quality are measured in terms of two different criteria, precision and recall. Evolutionary techniques are widely applied for optimization tasks in different areas including the area of information retrieval systems. In information retrieval applications both criteria have been combined in a single scalar fitness function by means of a weighting scheme 'harmonic mean'. Usage of genetic algorithms in the Information retrieval, especially in optimizing a Boolean query, is presented in this paper. Influence of both criteria, precision and recall, on quality improvement are discussed as well.
It has been known for a long time that for bootstrapping the distribution of the extremes under the traditional linear normalization of a sample consistently, the bootstrap sample size needs to be of smaller order than the original sample size. In this paper, we show that the same is true if we use the bootstrap for estimating a central, or an intermediate quantile under power normalization. A simulation study illustrates and corroborates theoretical results.