1.Radiological Morphometric Analysis for the Trabecular Bone Structure of Mandibular Condyle after Ovariectomy in Mature Cynomolgus Monkeys
Michiharu Shimamoto ; Yusuke Kozai ; Yukiko Matsumoto ; Ryota Kawamata ; Takashi Sakurai ; Isamu Kashima
Oral Science International 2007;4(2):86-96
To investigate the effects of experimental osteoporosis on the trabecular structure of the mandibular condyle in cynomolgus monkeys by radiological bone morphometry, ovariectomy (OVX) was performed on 10-year-old female cynomolgus monkeys, which were fed a controlled diet for 2 years. Ten sham control groups were fed under the same conditions. Using a microfocus tube and computed radiography, the removed mandibular condyle samples were imaged by standardized magnification radiography. The structural parameters were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The thickness of the cortical bone was measured using magnified radiographic images. The thickness of the cortical bone and the BMD in the OVX group were significantly lower than in the sham group. In the results of skeletal structure of the mandibular condyle, the trabecular structure of the mandibular condyle was markedly deteriorated in the OVX group. The trabecular structure of the mandibular condyle for the OVX group was significantly decreased, thus it was suggested that osteoporosis is a potential risk factor of osteoarthritis of the temporomandibular joint.
2.Systemic and myelotoxic effects of single administration of 2,3,7,8-tetrabromodibenzo-p-dioxin in rats.
Seigo YAMAMOTO ; Kasuke NAGANO ; Hideki SENOH ; Tetsuya TAKEUCHI ; Michiharu MATSUMOTO ; Hisao OHBAYASHI ; Tadashi NOGUCHI ; Kazunori YAMAZAKI ; Heihachiro ARITO ; Taijiro MATSUSHIMA
Environmental Health and Preventive Medicine 2006;11(3):136-144
OBJECTIVESystemic and myelotoxic effects of 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) were examined by the single administration of TBDD by gavage to rats.
METHODSFifteen Wistar rats of both sexes per group received 0, 10, 30, 100 or 300 μg TBDD/kg body weight. Rats surviving to the scheduled necropsy on Days 2, 7 and 36 after TBDD administration were examined for growth rate, organ weight, hematology, histopathology and adipose tissue levels of TBDD.
RESULTSThree 300 μg/kg-dosed females died on Days 21, 23 and 27, and exhibited a marked decrease in body weight, severe thymic atrophy, decreased bone marrow hematopoiesis and hemorrhage in the subarachnoid space of brain and spinal cord. TBDD-dosed surviving rats exhibited growth retardation, decreased bone marrow hematopoiesis, decreases in red blood cell counts, hemoglobin concentrations, and hematocrit values, an increase in reticulocytes and decreases in platelet counts, white blood cell counts and eosinophils. These signs suggested TBDD myelotoxicity. Splenic extramedullary hematopoiesis was increased in both sexes given TBDD, whereas atrophy of the splenic white pulp occurred only in TBDD-dosed females. Marked decreases in body weights and the size and weight of the thymus, severe thymic atrophy and death in TBDD-dosed females suggested a wasting syndrome. The adipose tissue level of TBDD culminated on Day 7 and decreased to 20-30% of the Day 7 level on Day 36.
CONCLUSIONSThe TBDD-induced effects were characterized by a wasting syndrome and myelotoxicity that appeared at the dose levels of 30 μg/kg and higher and caused death in 300 μg/kg-dosed females.