| Osteoporosis is a common health problem, especially in the elderly and in women after menopause. Although there are several therapeutic options available currently and administered clinically, side effects that constantly accompanied with osteoporosis-associated medicine still remain the most confounding and troublesome problems for physicians to deal with. Recently, the use of pulsing electromagnetic fields (PEMFs) has been a promising candidate for better treatment of osteoporosis. Unlike the other methods, PEMFs carry no known risks, cause no discomfort, and are considerably more cost effects.Electrical phenomena are found in all living organisms such as bone, nerve, cartilage, muscle, etc. Consequently, they can be influenced by external magnetic and electromagnetic fields as well. In fact, there is growing evidence that environmental electric and magnetic fields in the extremely low frequency band below 300Hz can influence biological functions by mechanisms that are only poorly understood at the present time. PEMFs have been used in the treatment of bone injuries and disorders for at least three decades. Extremely low frequency PEMFs been used in a variety of therapeutic applications, including healing of delay-union and non-union bone fractures, osteonecrosis, pseudarthrosis, promotion of nerve regeneration, and acceleration of wound healing. More than a million patients have been treated worldwide, with application to practically all areas of fracture management.The clinical trials of osteoporosis management by PEMFs were scarce even though there were abundant reports based on animal studies. An extensive scope of parameters of PEMFs (frequencies, repetition rates, pulse shapes, stimulation time, and intensities) has been employed and a large number of evaluation approaches have been applied for evidence of possible PEMFs effects. But the effects are still controversial and the mechanism is not yetclear.With an attempt to clarify and substantiate the efficacy of PEMFs onosteoporosis management, a series of in vivo and in vitro experiments were designed and performed this dissertation.In vivo experiments we investigated the preventive effects of PEMFs on bone loss in ovariectomized Sprague-Dawly rats and the influence of circadian rhythm on prevention in ovariectomized rats. The ovariectomized rats were electromagnetically radiated at the low-frequency of 15 Hz, electromagnetic pulse 5ms and under the intensity of 2 10-4T , 4 10-4T and 8 10-47T respectively for 12weeks(6h/d) and in different treatment time (daytime 9:00-15:00 and nighttime 0:00-6:00). We observed the change of serum osteocalcin, bone mineral density and histomorphometric measurement and calculations of distal femur and biomechanics characteristics and IL-1 , TNF- a proteins in the cancellous bone were examined by immunochemical SABC method in combined with the imaging analysis process.In vitro experiments we undertook the investigation to study the effects of PEMFs on osteoblastic differentiation, proliferation, cell cycle, apoptosis, bone nodule formation using a rat calvaria cell culture. MTT, p-nitrophenyl phosphate (pNPP), ARS(Alizarin red stain) or tetracycline fluorescence labelling were used to observe the proliferation, active of ALP and the number of the bone nodule formation. Apoptosis and cell cycle of osteoblast were examined by TUNEL technique and Flow cytometry(FCS). The expression of Cbfal , BMP-2 and Fas proteins were examined by immunochemical SABCmethod in combined with the imaging analysis process. We study the effect of PEMFs with different radiation time, differfht intensity ,different frequency upon the proliferation of osteoblast to investigate the "windows" effect areas. Conclusions:1. PEMFs stimulation augmented and restored bone mineral density, trabecular area, trabecular thickness , trabecular number and biomechanics characteristics. PEMFs exposure also attenuated the higher serum osteocalcin concentrations of OVX rats. PEMFs may be useful in the prevention of osteoporosis result...
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