Effect of 50-Hz Magnetic Fields on Argyrophilic Nucleolar Organizer Regions in Bone Marrow Cells

Background: Exposure to an increasing amount of extremely low-frequency magnetic fields (MFs) causes some adverse effects. Considering a direct association between the sizes and numbers of argyrophilic nucleolar organizer regions (AgNORs) and cell proliferation, this study was conducted to evaluate the effect of 50-Hz MFs on the AgNORs of bone marrow (BM) cells. Methods: Eighty male rats were randomly divided into four exposed groups and one control group. The exposed groups received 50-Hz MFs with magnetic flux densities of 1, 100, 500, and 2000 µT two hours a day for two months. BM cells were aspirated from sacrificed rats’ femoral bones, smeared on glass slides, and then stained with silver nitrate for AgNORs. The area (AA), length (AL), and number (AN) of AgNORs were calculated by a microscope equipped with a camera and Scion Image software in 100 BM cells of each rat. The mean of AA, AL, and AN was computed for each group. Results: AA, AL, and AN significantly reduced in the 1 µT group compared with 2000 µT and control groups. Eventually, there was a nonlinear relationship between the effect of 50-Hz MFs and magnetic flux densities. Conclusion: Overall, 50-Hz MFs with a magnetic flux density of 1 µT reduced AgNORs in BM cells. However, 100, 500, and 2000 µT did not affect AgNORs. Therefore, 50-Hz MFs with low density may suppress BM cell proliferation.

Avaliação quantitativa da expressão da proteína PCNA e das AgNORs em ameloblastomas

In order to assess the proliferative behaviour of the ameloblastoma epithelium nine cases of this neoplasm were retrieved from the files of the Oral Pathology Service laboratory of Rio Grande do Sul Federal University School of Dentistry. Two proliferation marker techniques were employed: the AgNor - argyrophilic nucleolar organizer regions staining and the proliferation cell nuclear antigen (PCNA) immunohistochemical assessment technique. Each case was submitted to a quantitative and comparative statistical analysis of the results obtained for the two techniques. The conclusion arrived at shows ameloblastoma presenting benign behavior, an average AgNOR index of 1.612, and a PCNA proteindependent proliferative activity with average immunoreactivity of 51.61%. The histological patterns analyses of the neoplastic epithelial component demonstrates that cells resembling pre-ameloblasts have obtained figures statistically higher to those obtained for cells resembling the stellate reticulum of the enamel organ, in both techniques employed. Therefore, it might be inferred that cells resembling pre-ameloblasts hold the proliferative potential of ameloblastomas and are probably responsible for the growth characteristics and infiltrative ability of this tumour.