Pulsed electromagnetic fields induced femoral metaphyseal bone thickness changes in the rat.

The effect of 1 Hz, 30 mT pulsed magnetic fields on young adult rat femoral metaphyseal bone thickness was assessed. Ten same litter, female Wistar rats were studied; five of them underwent 30 min magnetic stimulation sessions for 20 consecutive days. The anterior and posterior cortical, as well as trabecular bone transverse thicknesses were measured. The results obtained under clear field microscopy in stimulated and control histological cuts were (in microm) 398 +/- 32 versus 260 +/- 22 (P = 0.002), 380 +/- 68 versus 252 +/- 21 (P = 0.03), and 168 +/- 11 versus 112 +/- 11 (P = 0.002), respectively. The transcranial magnetic stimulation system, approved for human therapy, generates pulsed electromagnetic fields, which induce a significant thickness increase in cortical and trabecular in vivo stimulated bone tissues. This is the first time this effect in healthy animals is shown.

Neutral glycolipids in adult rabbit blood and analysis of their function as specific receptors for micro-organisms.

The adherence of the human respiratory pathogen Streptococcus pneumoniae serotype 6B, to whole blood cells from an adult rabbit (strain New Zealand) was analysed. Preliminary results obtained through thin layer and high performance liquid chromatography from derivatives of both a standard mixture of neutral glycolipids and of the extracted glycolipids from the rabbit's blood led us to the isolation and separation of four perbenzoylated derivatives, two of which could be tentatively identified as galactosylceramide and lactosylceramide. Over twenty four alditol acetates could be separated by gas-liquid chromatography after hydrolysis of the extracted blood glycolipids (1 mL). Comparison of their retention times with those of the standards revealed the presence of arabinose, galactose and glucose in micromolar amounts (less than 50 ng). Observations made by phase contrast microscopy showed a high density of attached bacterial cells to the defibrinated rabbit's blood, suggesting a clear host susceptibility towards the ligands present in the pathogen cells. These separated gas-liquid and high-performance liquid chromatography derivatives may serve as biological markers in further adhesion and inhibition assays characteristics of the host-pathogen relationship.