PubMed Health⌕ Search

Biomedical subjects

S Kawasoko

Publications and source records attributed to S Kawasoko.

15 recordsLinked to original sources
PubMed2000

Effects of insulin-like growth factor-I on nasopremaxillary growth under different masticatory loadings in growing mice.

It is well accepted that reduced masticatory function induced by a diet with soft physical consistency causes alterations in the craniofacial morphology in growing animals. It is assumed that these alterations are associated with reduced proliferative activity of osteoblasts on the bone surface, indicating a significant role for mechanical stimuli mediated by various local growth factors including insulin-like growth factor-I (IGF-I). Here, the effects of IGF-I on the linear growth of nasal and premaxillary bones subjected to different masticatory loadings were examined. The length of the nasal bone and the width of the premaxilla were measured. These dimensions were significantly greater in mice fed a solid diet than in mice fed a granulated diet. In animals treated with IGF-I, the nasal bone length and premaxillary width increased significantly in a subgroup receiving a solid diet, but these changes were not found in a similar group fed a granulated diet. No statistically significant differences in these dimensions were found between solid-diet mice injected with saline and granulated-diet group injected with IGF-I. It is concluded that IGF-I induces nasal and premaxillary growth, and that its effect is enhanced or accelerated by increased mechanical masticatory loading.

Analysis of Variance↗
PubMed1999

Recruitment of osteoclasts in the mandibular condyle of growing osteopetrotic (op/op) mice after a single injection of macrophage colony-stimulating factor.

The purpose was to elucidate histological changes in the mandibular condyle and ramus in growing osteopetrotic (op/op) mice after a single injection of macrophage colony-stimulating factor (M-CSF). M-CSF (5 microg) was injected into 6-, 11-, 26-, 56- and 86-day-old op/op mice, and the mice were killed 4 days after the injection. In normal mice, the condyle was substantially wider than the ramus beneath it, and enlargement and ossification of the condyle occurred after weaning. These changes were not found in the uninjected and injected op/op mice, the condyles of which were occupied by hypertrophic cartilage cells, and the hypertrophic cell layer was thicker and more irregular in the arrangement of epiphyseal cell columns. In spite of the lack of bone resorption in uninjected and injected op/ op mice, ossification of the mandibular ramus occurred, but later than that of normal mouse. The number of tartrate-resistant acid phosphatase-positive cells in the injected op/op and normal mice approached a maximum at 30 days and then gradually decreased up to 90 days of age, although the numbers were substantially different for all ages. The uninjected op/op mice had no visible osteoclasts until 15 days and their number then increased significantly from 60 to 90 days of age. These results were considered due to the difference in biological responses of bony structures to M-CSF injection in the op/op mice. The influences of mechanical stimuli from masticatory functions, which are deficient in op/op mice, might also be responsible for the differences in bony architecture between the op/op and normal mice.

Animals↗
PubMed1998

Midpalatal suture of osteopetrotic (op/op) mice exhibits immature fusion.

The midpalatal suture was observed histologically in both toothless osteopetrotic (op/op) and normal (control) mice. The normal mice had a mature sutural structure, which consists of a well-developed cartilage cell zone and palatal bone. In contrast, the thickness of the cartilage cell zone was substantially greater in the op/op mice than that in the controls. Moreover, the cartilage cells in the op/op mice were frequently found in the palatal bone as well as in the sutural space, exhibiting an imperfect fusion. It seems that immature fusion at the sutural interface in the op/op mice is related to a decrease in biting or masticatory force accompanied by the failure of tooth eruption in addition to an essential defect in osteoclast differentiation, which is a congenital symptom in op/op mice.

Animals↗
PubMed1998

Suspension "hypokinesia/hypodynamia" may decrease bone mass by stimulating osteoclast production in ovariectomized mice.

This study was conducted to examine, in detail, the histological changes in the femurs of suspended ovariectomized (OVX) mice to assess the role of mechanical stress on bone remodeling. Suspended-OVX, suspended-sham-ope, nonsuspended-OVX, and nonsuspended-sham-operated mice underwent operations 8 weeks after birth. Immediately after operation, hypokinesia/hypodynamia was created by a suspension harness for one week. Five specimens in each group were sacrificed 9 weeks after birth. The trabecular bone of the femurs in the suspended-OVX mice was removed and replaced extensively by bone marrow. The number of tartrate-resistant acid phosphatase (TRAP)-positive cells was larger in the suspended-OVX mice than in the remaining three groups. No significant differences in the number of TRAP positive cells were found between the suspended-sham-ope, nonsuspended-OVX and nonsuspended-sham-ope mice. The femurs of the OVX mouse with suspension "hypokinesia/hypodynamia" thus exhibits extensive trabecular bone loss in association with an increase of osteoclasts.

Acid Phosphatase↗
PubMedDate not supplied

Morphological change of the nasopremaxillary suture in growing "toothless" osteopetrotic (op/op) mice.

Osteopetrotic (op/op) mice are known to commonly show a failure of tooth eruption. It is also well understood that masticatory function is highly associated with the craniofacial morphology of the growing mouse; however, the effects on sutural growth have not been studied. The present study was conducted to examine, in detail, the morphological and histological changes of the nasopremaxillary suture in these mutant mice and to assess a role of mechanical stress from mastication in the sutural growth. The width of the nasopremaxillary suture was measured on the section for the superior (P1), middle (P2), and inferior (P3) levels. The width of the nasopremaxillary suture for the P1 level in the normal mice fed a solid diet was significantly smaller in 30-day-old mice than in 15-day-old mice, whereas the width for the level P3 was significantly greater in the 30-day-old mice than in the 15-day-old mice. These changes in the sutural space were more prominent in the normal mice fed a solid diet than in the normal mice fed a granular diet. The sutural widths for all the levels became smaller in the 30-day-old op/op mice than in the 10-day-old op/op mice. The endocranial area of the nasopremaxillary suture showed synostosis in 30-day-old op/op mice. In both the normal and op/op mice, the number of tartrate-resistant acid phosphatase (TRAP)-positive cells was greatest at the age of 15 days. Moreover, the TRAP-positive cell number was smaller in the op/op mice than in the normal mice for all the experimental stages. Since, in general, mastication begins in mice after tooth eruption, i.e. from 15 to 30 days after birth, the present findings suggest that failure of tooth eruption and the reduced masticatory function restrict sutural modification.

Animals↗
PubMedDate not supplied

Remodeling of the sagittal suture in osteopetrotic (op/op) mice associated with cranial flat bone growth.

It is well known that cranial flat bone experiences growth and development at the sutural interface, which is regarded as a neutral zone to control mechanical stimuli. In osteopetrotic (op/op) mice, meanwhile, cranial deformation is produced by the deficiency of osteoclasts and the subsequent defect of bone resorption. It would be a reasonable assumption that such disturbance in bone remodeling affects sutural modification and the relevant cranial flat bone development. The present study was thus conducted to examine histological features of the sagittal sutures in op/op mice, with special reference to the relevant bone remodeling. The sagittal sutures in 10-, 15-, 30-, and 60-day-old normal and op/op mice were observed microscopically. Furthermore, osteoclastic activity was evaluated on the sections stained with tartrate-resistant acid phosphatase (TRAP). The sutures of 15-day-old op/op mice showed stenosis and synostosis, and less-developed collagen fibers associated with an irregular arrangement of fibroblasts, whereas these changes were rarely found in normal mice. Osteoclasts were hardly detected in the parietal bones around the sutures of op/op mice, although the number was numerous in normal mice. These results emphasize that congenital deficiency in osteoclast produces unbalanced bone remodeling at the sutural interface and on the surfaces of the cranial bones, which is assumed to be closely related to cranial bone deformity in op/op mice.

Animals↗
PubMedDate not supplied

Lack of the bone remodeling in osteopetrotic (op/op) mice associated with microdontia.

Osteopetrosis is an inherited metabolic disease characterized by an excessive accumulation of bone. This is associated with an osteoclast deficiency. Osteopetrosis is always accompanied by the failure and/or delay of tooth eruption. The present study was conducted to examine in detail the morphological and histological changes of growth of the third molars in the osteopetrosis (op/op) mouse. At the age of 10 days, normal and op/op mice showed no detectable difference in the shape of the third molar follicles. However, the third molars in the op/op mouse became obscured by the proliferation of neighboring bone trabeculae. Moreover, no tartrate-resistant acid phosphatase-positive cells were detected on the bone surfaces of 10-day-old op/op mice. Ankylosis between the root dentin and proliferating bone trabeculae was a common feature in the 20- and 30-day-old op/op mice. The third molars erupted into the oral cavity before the age of 30 days in normal mice, and the crowns, roots, and periodontal ligaments appeared well developed. Throughout the experiment, it seemed that the primary cause of the microdontia and ankylosis of the developing root in the mutant mouse was a deficiency of osteoclasts, with attendant lack of bone remodeling.

Age Factors↗
PubMedDate not supplied

Influences of osteoclast deficiency on craniofacial growth in osteopetrotic (op/op) mice.

It is well known that the defect in bone resorption in osteopetrotic (op/op) mice brings about deformation of the cranium and failure of tooth eruption. However, the influences on longitudinal growth of the craniofacial skeleton have not been elucidated. This study was thus conducted to examine craniofacial morphology and longitudinal changes in the op/op mice by means of morphometric analysis with lateral cephalograms. Lateral cephalograms, taken every 10 days from 10- to 90-day-old mice, were analyzed on a personal computer for 11 measurement items. For the nasal bone region, the most prominent differences were found between the op/op and normal mice. The anterior cranial base and occipital bone height presented almost equivalent growth changes in both the op/op and normal mice. The size of mandible, meanwhile, was significantly smaller in the op/op mice than in the normal controls. The gonial angle was also significantly larger in the op/op mice than in the normal mice throughout the experimental period. Thus, substantial differences in craniofacial growth were demonstrated in various areas of the craniofacial complex, which are assumed essentially due to the lack of osteoclastic bone resorption during growing period. Since the difference became more prominent in the anatomic regions relevant to the masticatory functions, it would be a reasonable assumption that reduced masticatory function is also a key determinant for the less-developed craniofacial skeleton in the op/op mouse.

Animals↗
PubMedDate not supplied

Morphology of the mandibular condyle in "toothless" osteopetrotic (op/op) mice.

The defective bone resorption in the osteopetrotic op/op mouse brings about cranio-facial deformation and failure of tooth eruption. This study was conducted to elucidate the morphological changes of the condylar head and mandibular ramus in growing op/op mice. In normal mice, the condylar head is much broader than the ramus beneath it, enlargement and ossification of the condylar head begin after weaning, and the ramus becomes compact bone tissue. None of these changes were found in the op/op mice in the present observation. The condylar head was small, and its inner side was occupied by hypertrophic cartilage cells. In spite of the lack of bone resorption in op/op mice, the compaction of the mandibular ramus, which was composed of bone trabeculae, occurred later than that in normal mice. In view of recently studies reported evidence that local mechanical stress regulates the bone formation, we consider that undergrowth of the condylar head and the ramus in the op/op mouse results from not only a deficiency of osteoclasts but also insufficient mechanical stress from mastication.

Animals↗
PubMedDate not supplied

Influences of ovariectomy and orchiectomy on the remodeling of mandibular condyle in mice.

Ovariectomy (OVX) and orchiectomy (ORX) are well known to increase bone turnover; however, the influences on condylar remodeling are not fully understood. The purpose of this study was to examine histological changes of the mandibular condyles in OVX and ORX mice in comparison to the femora. Eighty 8-week-old mice were used in this study. In each of the experimental and control groups, five mice were sacrificed 2, 4, 8, and 12 weeks after surgery for OVX and ORX. Histological changes of the mandibular condyle were studied in comparison to the femur, which is liable to undergo the influences of OVX and ORX. The number of TRAP-positive cells and the thickness of articular cartilage layer were also quantified. TRAP-positive cells in the condylar head of OVX and ORX mice exhibited the most prominent increase 4 weeks after the surgery and approached the control levels at the later experimental stages. Trabecular bone volume in the condyle of the OVX and ORX mice also decreased, although the rate was less than in the femora. It is shown that influences of OVX on the remodeling of femora appear earlier than those of ORX, whereas OVX and ORX affect the remodeling of condyle during the same growth period. It is also demonstrated that the influences of OVX and ORX are less in the condyle than in the femora. These findings emphasize that the influences of OVX and ORX on bone remodeling are varied by sexual difference and the type of bones.

Acid Phosphatase↗