Bones are stained into red color with feeding madder, but we do not know whether the fed madder can change the bone biomechanical properties and bone mineral contents in animals. In this research, we established a rat model with feeding madder. The bone biomechanical properties were detected by universal material mechanics, bone mineral contents were detected by inductively coupled plasma mass spectrometry and spectrometer, and red color material in bone was analyzed by high performance liquid chromatography. The results showed that bone biomechanical parameters in femur diaphysis in the 10% and 15% group rats were significantly higher than those in the control group after feeding madder for 6 months. The level of calcium, magnesium and zinc in femur diaphysis in 10% and 15% group rats were higher than those in the control group after feeding madder for 6 months. However, it was shown that the kidney congestion andhyperemia and the level of blood urea nitrogen and creatinine in the 15% group rats were significantly different compared to those in the control group rats after feeding madder for 6 months. The red colored material in bone is related to alizarin analyzed with high-performance liquid chromatography. The conclusion could be drawn that feeding 10% madder in diet was not toxic to the rats fed for 6 months, and it could improve bone biomechanical properties and increase bone mineral elements.
The present research is to investigate the time effect of sinusoidal electromagnetic fields (SEMFs) at different exposure time on the biomechanical properties in rats, and to find a best time for improving biomechanical properties. Forty female SD rats were randomly divided into five groups, i.e. control group, 45 min SEMFs group, 90 min SEMFs group, 180 min SEMFs group, and 270 min SEMFs group. In addition to the control group, other groups were exposed to 50 Hz and 0.1 mT magnetic field every day for the corresponding time periods. After eight weeks, bone mineral density (BMD), bone biomechanics, bone tissue morphology, micro-CT and pathological examination were performed. The results showed that there was no abnormal pathological finding in the experimental groups. In the 90 min SEMFs group, BMD, femur maximum load, elastic modulus, yield strength, trabecular number (Tb.N), trabecular thickness (Tb.Th) and trabecular area (Tb.Ar) percentage were all significantly higher than those in the control group (P＜0.01), and trabecular separation (Tb.Sp) was significantly lower than that of the control group (P＜0.01). However, for other experimental groups, some indices showed statistical significance compared to the control group (P＜0.05), but some did not (P>0.05). This study showed that under 50 Hz and 0.1 mT SEMFs, 90 min is the best time that can effectively increase bone mineral density, improve the bone tissue microstructure organization and the biomechanical properties.