الفهرس 
INTRODUCTION AND AIM OF THE WORK
Bone structure, growth, modeling, remodeling and agingOnly 14 pages are availabe for public view
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Abstract
Osteoporosis is a multifactorial skeletal disease, characterized by reduction in bone mass and disruption of bone microarchitecture, resulting in loss of mechanical strength and increased risk of fracture. Osteoporosis is estimated to affect 200 million women worldwide. The major health consequence of this condition is osteoporotic fractures. The bone loss that precedes the osteoporotic fracture seems to be a symptomless process, so osteoporosis may go undetected until bones become so brittle that even the slightest trauma would cause a fracture. According to The Egyptian Osteoporosis Prevention Society (EOPS), more than 50% of postmenopausal women have osteopenia and more than half of these have osteoporosis. Postmenopausal estrogen deficiency is a critical factor of the pathogenesis of osteoporosis. Although osteoporosis is influenced by many genetic, hormonal and nutritional factors, yet the exact mechanism of its pathogenesis is not completely known. Induction of osteoporosis in animal model is a good tool in investigating the changes which occur in osteoporosis and the possibility of reversibility of these changes using various therapeutic interventions. The present study was performed to investigate the histological and radiological impact of ovariectomy and corticosteroid administration on the cancellous and compact bone of the albino rat as represented by the lumbar vertebrae and femoral shaft. The study aimed also to assess the protective and therapeutic effects of bovine colostrum on these induced bony changes. A total number of 120 adult female albino rats, 3 months old were used in the present study. The rats were divided randomly into 2 main groups: group ( I ) included 40 rats and considered as a control group. These rats were subdivided into two subgroups 20 rats each. •Subgroup Ia were sacrificed at the age of 6 months and •Subgroup Ib sacrificed at the age of 9 months. group (II) included 80 rats used as an experimental group and subdivided into 4 subgroups, 20 rats each. •Subgroup IIa, early osteoporotic group, where the rats were subjected to bilateral ovariectomy and corticosteroid administration for 3 months. •Subgroup IIb, prophylactic group, where the ovariectomised glucocorticoid treated rats received concomitant 1ml / day of bovine colostrum for 3 months. •Subgroup IIc, late osteoporotic group, where the rats were subjected to bilateral ovariectomy and corticosteroid administration for 6 months •Subgroup IId, therapeutic group, where the ovariectomised glucocorticoid treated rats received 1ml / day of bovine colostrums for 3 months after a latent period of 3 months. In each of the studied subgroups, the femora and the lumbar vertebrae were extracted. Half of the specimens were decalcified using EDTA solution for 3-5 weeks and processed for light, scanning, and transmission electron microscopic examination to investigate bone structure, stages of ossification, bone architecture and detailed cellularity. The other half of the specimens was exposed to radiological examination using plain X-ray and DEXA scan to evaluate the bone mineral density and its score. Mean values of trabecular thickness of the 5th lumbar vertebra and the cortical thickness of the mid femoral shaft were measured and compared among the control versus the different corresponding experimental groups. Statistical analysis (SPSS) was performed to test the significant difference between the mean values of the different groups. In the early osteoporotic group, the lumbar vertebrae showed disruption of the zones of ossification and thinning of bone trabeculae with relative increase in marrow spaces. Many irregular multinucleated osteoclasts were recognized as well. The mean value of trabecular thickness was significantly decreased to 21 μm in comparison with 50μm in the control. Plain X- ray showed rarified vertebral bodies. DEXA scan showed decrease in bone density to become 0.5gm/cm3 in comparison with 0.9gm/cm3 in the control. In the femoral specimens, the osteonal system was destructed; the cortical thickness was significantly decreased to 203μm in comparison with 301μm of the control. Bone mineral density was significantly decreased to 0.68gm/cm3 in comparison with 1.1gm/cm3 of the control. In the late osteoporotic group, the lumbar vertebrae showed disorganization of different zones of ossification, appearance of osteolytic cavities and marked thinning of bone trabeculae. Some vertebrae exhibited signs of collapse. The mean trabecular thickness became 21μm in comparison with 75μm of the control. DEXA scan showed prominent decrease in bone mineral density to become 0.37 gm/cm3 in comparison with 0.9gm/cm3 of the control. The femoral shaft of the late osteoporotic group showed massive destruction of bone architecture with multiple cavities and microcraks. The osteocytes showed shrunken nuclei and withdrawn processes. The cortical thickness significantly decreased to 189μm in comparison with 329μm of the control. DEXA scan revealed marked decrease in bone mineral density to become 0.54gm/ cm3 in comparison with 1.1gm/cm3 of the control. It was observed that the bone loss of the early osteoporotic vertebrae to be 58% whereas in the late osteoporotic vertebrae it was 72%. In the early osteoporotic femora, bone loss was 32% whereas in the late osteoporotic femora bone loss was 42%. The prophylactic group showed marked preservation of the bone structure and architecture. The lumbar vertebrae showed preserved thickness of their epiphyses with minimal disruption of zones of ossification. The vertebral bodies showed preservation of trabecular thickness. Percentage bone loss was only 15%. DEXA scan revealed marked preservation of bone density to become 0.75gm/cm3 in comparison with 0.50gm/cm3 of the early osteoporotic group. In the femoral specimens, the cortical thickness was preserved with properly oriented osteonal system. Percentage of bone loss was only 13%. Osteocytes showed nearly normal structure. Bone mineral density was within the normal range. The therapeutic group showed marked improvement of bone histomorphometry. The lumbar vertebrae showed moderate restoration of thickness of their epiphyses with reorientation of different zones of ossification. The trabecular thickness was markedly increased. Bone loss was only 25% compared to 72% of the late osteoporotic group. DEXA scan showed marked restoration of bone mineral density to be moved high in the osteopenic area (bone density slightly less than normal). In the femoral specimens, the cortical thickness improved and the osteonal system restored its normal lamellar pattern. Osteocytes appeared to be normal. Bone loss was 33% only and the bone mineral density showed marked improvement to reach slightly less than normal level. It appeared that loss in cancellous bone was almost as twice as that of compact bone in the early and late stages of osteoporosis. These variations in the rate of bone resorption are most probably due to the difference in the pattern of bone construction as well as the pattern of insertion of voluntary muscles. The regular lamellar construction of cortical bone coupled with more mineralized matrix make this type of bone more resistant to resorption. In conclusion, bilateral ovariectomy and corticosteroid administration resulted in marked osteoporotic bony changes in the vertebral cancellous and femoral compact bone. Concomitant administration of bovine colostrums with the induction of osteoporosis has documented the prophylactic value of colostrum in preventing the progress of osteoporosis. Administration of bovine colostrum after 3 months latent period in the osteoporotic induced rats has shown promising therapeutic ameliorating effects on the well established osteoporosis.