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  • 1
    ISSN: 1436-2023
    Keywords: Key words: men, aging, cortical bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: Metacarpal cortical bone mass was measured in 507 healthy Japanese men aged 40–95 years, using a microdensitometer to determine age-related changes in cortical bone in these middle-aged and elderly men. Total bone mass showed a significant negative correlation with age (r = −0.281; P 〈 0.0001). While bone width showed no significant correlation with age, bone marrow width showed a significant positive correlation (r = 0.210; P 〈 0.0001), and cortical bone width and cortical bone density showed a significant negative correlation with age (r = −0.265; P 〈 0.0001; r = −0.268; P 〈 0.0001, respectively). On the other hand, cortical bone width and cortical bone density showed a significant positive correlation with total bone mass (r = 0.814; P 〈 0.0001; r = 0.474, P 〈 0.0001, respectively). These findings suggest that cortical bone mass decreases significantly with aging in middle-aged and elderly men, perhaps as a result of two factors — decreased cortical bone width, ie, cortical bone thinning due to bone loss at the endosteal side of the cortex, and decreased cortical bone density due to progression of intracortical porosity. Cortical bone thinning may influence age-related cortical bone loss more than decreasing cortical bone density.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-5604
    Keywords: Intercellular communication ; Gap junction ; Calcification ; Collagen gel ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To analyze the mechanism of initiation of cell-mediated calcification in hard tussue and its relationship to the frequency of gap junctions, enzymatically isolated cells from fetal rat calvaria cultured in collagen gels were observed ultrastructurally over a time course. Calcification was observed at 2–3 weeks after the initiation of culture when the seeding cellularity and the concentration of β-glycerophosphate were sufficiently high. In the collagen gels, round cells (R), spindle or stellate cells (S), and fat cells (F) were characterised morphologically. The ultrastructural features of initial calcification could be classified into 4 subtypes: 1) a large mass greater than 10 µm in diameter (Type I), 2) deposition associated with dead R cells or matrix vesicles (Type II), 3) intracellular deposition (Type III), and 4) other than Types I–III (Type IV). Type II was the most frequent (44.5%) and Type III was the least (6.8%). Gap junction was observed frequently between 1) R cells, 2) S cells, 3) between R cells and S cells. The frequency of gap junctions in collagen gels decreased statistically (X2-test; p〈0.001), when calcification was initiated. This cell culture system can be regarded as a useful model to analyze the initiation of cell mediated calcification in hard tissue. Gap junctions might function in cell communication and a decrease in their numbers could lead to cell death and, subsequently to calcification.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1436-2023
    Keywords: Key words Vitamin D3 ; Vitamin K2 ; Postmenopausal women ; Osteoporosis ; Bone mineral density (BMD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of the combined administration of vitamin D3 and vitamin K2 on bone mineral density (BMD) of the lumbar spine was examined in postmenopausal women with osteoporosis. Ninety-two osteoporotic women who were more than 5 years after menopause, aged 55–81 years, were randomly divided into four administration groups: vitamin D3 (1α hydroxyvitamin D3, 0.75 μg/day) (D group; n = 29), vitamin K2 (menatetrenone, 45 mg/day) (K group; n = 22), vitamin D3 plus vitamin K2 (DK group, n = 21), and calcium (calcium lactate, 2 g/day) (C group; n = 20). BMD of the lumbar spine (L2–L4) was measured by dual energy X-ray absorptiometry at 0, 1, and 2 years after the treatment started. There were no significant differences in age, body mass index, years since menopause, and initial BMD among the four groups. One-way analysis of variance (ANOVA) with repeated measurements showed a significant decrease in BMD in the C group (P 〈 0.001). Two-way ANOVA with repeated measurements showed a significant increase in BMD in the D and K groups compared with that in the C group (P 〈 0.05 and P 〈 0.001, respectively), and a significant increase in BMD in the DK group compared with that in the C, D, and K groups (P 〈 0.0001, P 〈 0.05 and P 〈 0.01, respectively). These findings indicate that combined administration of vitamin D3 and vitamin K2, compared with calcium administration, appears to be useful in increasing the BMD of the lumbar spine in postmenopausal women with osteoporosis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of orthopaedic science 3 (1998), S. 257-263 
    ISSN: 1436-2023
    Keywords: Key words: osteopenia ; treadmill running exercise ; mechanical loading ; bone histomorphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: The effect of moderate running exercise on tibial and lumbar vertebral bone mass was examined in mature osteopenic rats by bone histomorphometry. Ten 37-week-old female Wistar rats, with bone loss resulting from being fed a relatively low-calcium diet for 14 weeks after ovariectomy at the age of 23 weeks, were randomly divided into two groups of five animals each; control and exercise groups. The exercise consisted of treadmill running at 12 m/min for 1 h per day on 5 days per week for 12 weeks. During the exercise period, all animals were fed a standard calcium diet. After 12 weeks of exercise, bone histomorphometry was evaluated for cancellous bone (secondary spongiosa) of the proximal tibia and the fourth lumbar vertebra and for cortical bone of the tibial shaft. The findings suggested that in the mature osteopenic rat, there was a beneficial effect of moderate running exercise with adequate calcium intake on bone mass only in a weight-bearing long bone, the tibia. The mechanism for increased bone mass appeared to be both decreased bone resorption and increased bone formation in cancellous bone and increased bone formation in cortical bone.
    Type of Medium: Electronic Resource
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