OBJECTIVESEpidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors, leukemia, and other neoplasms. The aim of this study was to investigate the genotoxic effects of exposure to 50-Hz EMFs. and of co-exposure to cisplatin, a mutagen and carcinogen, and 50-Hz EMFs, using an in vivo newborn rat astrocyte micronucleus assay.

METHODSThree day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and 1.25 or 2.5 mg/kg of cisplatin. Brain cells were dissociated into single cells and cultured for 96 hours, then stained with acridine orange and an antibody against glial fibrillary acidic protein. The frequency of micronucleated astrocytes was counted with a fluorescent microscope.

RESULTSThe frequency of micronuclei was not increased in rat astrocytes exposed to EMFs alone. However, the frequencies of micronuclei in co-exposure to 2.5 mg/kg cisplatin and EMFs (7.5- and 10-mT) were significantly increased, compared with those in exposure to 2.5 mg/kg cisplatin alone (sham-exposure, 0-mT EMFs) for 72 hours (p<0.01).

CONCLUSIONExposure to EMFs alone did not have a genotoxic effect but co-exposure to EMFs increased the genotoxic activity induced by cisplatin. Our findings suggest that EMFs enhance the genotoxic effects of cisplatin.

OBJECTIVESAn increase in incidence of the illegal use of tablets containing 3,4-methylenedioxymethamphetamine hydrochloride (MDMA) has recently become a widespread social problem. MDMA ingested orally reacts with nitrite in the stomach and is synthesized intoN-nitroso-3,4-methylenedioxymethamphetamine (N-MDMA). The aim of this study is to investigate the genotoxic effects of MDMA and N-MDMA on the basis of the results of an in vitro micronucleus (MN) test and an in vitro chromosomal aberration (CA) test using a Chinese hamster lung fibroblast cell line (CHL/IU).

METHODSTablets containing MDMA obtained from the Regional Bureau of the Ministry of Health, Labor and Welfare were purified, and N-MDMA was synthesized from MDMA in our laboratory. To evaluate the effects of MDMA and N-MDMA, the MN test established by our laboratory and the CA test in accordance with the guidelines for toxicity studies of drugs recommended by the Ministry of Health, Labor and Welfare were performed.

RESULTSIn the MN test, no increased frequency of MNs was not found for MDMA. On the other hand, an apparently increased frequency of MNs was observed for N-MDMA. In the CA test, no CA was found for MDMA, but CA was observed for N-MDMA apparently.

CONCLUSIONN-MDMA genotoxicity was observed in the MN and CA tests. However, no MDMA genotoxicity was observed.

OBJECTIVESIt is important to assess the risk of static magnetic fields (SMFs) on human health, because epidemiological studies have indicated that SMFs play a role in the development of diseases such as leukemia and brain tumor. In our environment, we have numerous chances to be exposed to not only SMFs but also many chemicals containing mutagens. The aim of this study is to investigate the effect of SMFs on the induction of micronuclei induced by some mutagens.

METHODSBALB/c mice were exposed to 4.7 tesla (T) SMF for 24 hr immediately after the injection of carboquone (alkylating agent), colcemid (spindle poison), mitomycin C (cross-linking agent), vincristine (spindle poison), sodium fluoride (a byproduct of aluminum plants under strong SMF) or 1-ethyl-1-nitrosourea (brain tumor-, gliomas- and thymic lymphoma-inducing chemical).

RESULTSThe frequency of micronuclei induced by six mutagens increased after co-exposure to SMF.

CONCLUSIONSAn additive/synergistic effect of SMF and chemicals was observed from the results of increased frequency of micronuclei induced by mutagens in mouse bone marrow erythrocytes.

OBJECTIVESKetamine hydrochloride (KT) is a secondary amine that has been safely used as an injectable anesthetic and analgesic to avoid the production of nitroso compounds in the stomach. However, ketamine in the tablet form has recently become an abused, recreational drug. The aim of this study was to investigate the genotoxic effects of N-nitrosoketamine (NKT) and KT on the basis of an in vitro micronucleus (MN) test using a Chinese hamster lung fibroblast cell line (CHL/IU).

METHODSNKT was synthesized from KT in our laboratory. In the MN tests, CHL/IU cells were continuously treated with either NKT or KT for 24, 48, or 72 hours without the S9 mix. The cells were also treated with NKT or KT with or without the S9 mix for 6 hours, followed by a recovery period of 18, 42, or 66 hours (short-term treatment). The results were considered to be statistically significant when the p-values of both Fisher's exact test and the trend test were less than 0.05.

RESULTSAfter the short-term treatment with either NKT or KT with and without the S9 mix, the frequency of micronuclei significantly increased. However, the frequency of micronuclei did not significantly increase after the continuous treatment with either NKT or KT. Both NKT and KT were determined to be genotoxic in the short-term treatment with or without the S9 mix, but they were determined to be nongenotoxic in continuous treatment.

CONCLUSIONOur findings suggest that NKT has a stronger genotoxic effect than KT.

OBJECTIVES: Glucocorticoid (GC) treatment inhibits activation of runt-related transcription factor 2 (Runx2), which is essential for osteoblast differentiation from stem cells. As a result, GC treatment results in bone loss, GC-induced osteoporosis (GIO), elevated fracture risk, and delayed bone healing. Bisphosphonates such as alendronate (ALN) are recommended for treating or preventing GIO, and lowintensity pulsed ultrasound (LIPUS) facilitates fracture healing and maturation of regenerated bone. Combined therapy with ALN and LIPUS may stimulate cancellous bone healing in GIO rats. Here, we examined the effect of ALN and LIPUS on cancellous bone osteotomy repair in the proximal tibia of GIO rats. METHODS: Prednisolone (10 mg/kg body weight/day) was administered for 4 weeks to induce GIO in 6-month-old female Sprague-Dawley rats. Tibial osteotomy was then performed and daily subcutaneous injection of ALN (1-µg/kg body weight) was subsequently administered alone or in combination with LIPUS (20 min/day) for 2 or 4 weeks. RESULTS: ALN significantly increased bone mineral density (BMD) at 2 and 4 weeks, and ALN + LIPUS significantly increased BMD at 4 weeks. Bone union rates were significantly increased after 2 and 4 weeks ALN and ALN + LIPUS treatment. Lastly, ALN and ALN + LIPUS significantly increased the proportion of Runx2 positive cells at 4 weeks. CONCLUSIONS: ALN monotherapy and combined ALN and LUPUS treatment augmented BMD and stimulated cancellous bone repair with increased Runx2 expression at the osteotomy site in GIO rats. However, the combined treatment had no additional effect on cancellous bone healing compared to ALN monotherapy.
Alendronate* ; Animals ; Bone Density ; Bone Diseases, Metabolic* ; Diphosphonates ; Female ; Fracture Healing ; Humans ; Infant ; Injections, Subcutaneous ; Osteoblasts ; Osteoporosis ; Osteotomy* ; Prednisolone ; Rats* ; Rats, Sprague-Dawley ; Stem Cells ; Tibia* ; Transcription Factors ; Ultrasonic Waves*

STUDY DESIGN: Retrospective and comparative study. PURPOSE: We assessed surgical treatment outcomes in patients with thoracic myelopathy due to ossification of the ligamentum flavum (OLF), and OLF combined with ossification of the posterior longitudinal ligament (OPLL) or vertebral fracture (VF) at the same level. OVERVIEW OF LITERATURE: OLF and OPLL cause severe thoracic myelopathy. Osteoporotic VF commonly occurs at the thoracolumbar junction. There have been no investigations of thoracic myelopathy due to OLF and VF. METHODS: Forty patients were divided among three groups: the OLF group (n=23): myelopathy due to OLF, the OLF+OPLL group (n=12): myelopathy due to OLF and OPLL, and the OLF+VF group (n=5): myelopathy due to OLF and VF. We recorded OLF, OPLL, and VF sites and operative procedures. Each patient’s neurological status, according to the Japanese Orthopaedic Association (JOA) score, and walking ability were evaluated pre- and postoperatively. RESULTS: Patients in the OLF+OPLL group were significantly younger than those in the other two groups. The preoperative JOA score was significantly lower in the OLF+VF than OLF group. The final JOA score was significantly lower in the OLF+VF than OLF and OLF+OPLL groups. The JOA score recovery rate was significantly lower in the OLF+VF than OLF group. Final walking ability was significantly worse in the OLF+OPLL and OLF+VF groups than in the OLF group and significantly worse in the OLF+VF than OLF+OPLL group. CONCLUSIONS: Thoracic myelopathy due to OLF+VF occurs primarily in older females, who also exhibit worse preoperative and postoperative neurological status, and worse walking ability, than patients with thoracic myelopathy due to OLF or OLF+OPLL.

OBJECTIVES: Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovium, progressive erosion of the articular cartilage, and joint destruction. RA also causes secondary osteoporosis and muscle wasting. We investigated the effects of ibandronate (IBN), a bisphosphonate; eldecalcitol (ELD), an active vitamin D3 derivative; and combination treatment with both agents on secondary osteoporosis and muscle wasting using adjuvant-induced arthritis rats. METHODS: Arthritis was induced in 8-week-old male Lewis rats. Rats were randomized into 4 treatment groups and an untreated normal control group: IBN (subcutaneously, once every 2 weeks, 10 µg/kg), ELD (orally, once daily, 30 ng/kg/day), IBN + ELD, vehicle, and control. Paw thickness measurements were performed for evaluation of arthritis. The femur was scanned using dual-energy X-ray absorptiometry. Cross-sectional areas of left tibialis and anterior muscle fibers and the expression of MuRF1, atrogin-1, MyoD, and myogenin in the gastrocnemius muscle were measured to evaluate muscle wasting. RESULTS: IBN and/or ELD increased bone mineral density (BMD) in the femur. In addition, there was an additive effect of combination treatment compared with single treatments for BMD. However, IBN and/or ELD did not inhibit muscle wasting in adjuvant-induced arthritis rats. CONCLUSIONS: Combination treatment with IBN and ELD may be effective for secondary osteoporosis associated with RA. Other treatments are necessary for muscle wasting associated with RA. Studies in humans are needed to confirm these findings.
Absorptiometry, Photon ; Animals ; Arthritis ; Arthritis, Rheumatoid ; Bone Density ; Cartilage, Articular ; Cholecalciferol ; Femur ; Humans ; Inflammation ; Joints ; Male ; Muscle, Skeletal ; Myogenin ; Osteoporosis ; Rats ; Synovial Membrane ; Vitamin D