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  • 1
    Electronic Resource
    Electronic Resource
    Changes in bone mineral in experimentally induced rickets in the rat: Electron microprobe and chemical studies (1980)
    Springer
    Calcified tissue international 30 (1980), S. 135-146 
    Details
    ISSN: 1432-0827
    Keywords: Rickets ; Vitamin D ; Bone mineral ; Hypophosphatemia ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The elemental composition of trabecular bone was compared for: (a) rats made rachitic on a low phosphorus, vitamin D-deficient diet; (b) rats fed the same diet but supplemented with vitamin D; (c) normal rats fed a standard laboratory diet with normal phosphorus and vitamin D levels. Quantitative energy dispersive X-ray microanalysis was performed on mineralized bone matrix at four sites: (1) clusters of mineral crystals in osteoid; (2) bone matrix adjacent to osteoid containing mineralization clusters; (3) peri-lacunar bone matrix; and (4) deep bone matrix distant from osteocytes. Estimations were also made of serum calcium, phosphorus, and 25-hydroxy-vitamin D, and of calcium, phosphorus, and hydroxyproline in whole bone. At bone sites 2, 3, and 4, the mineral content was greater in the normal group than in the other two groups. At each site, the mineral content of the rachitic bone matrix was greater than that from the vitamin D-treated group. A normal pattern of increasing mineral content with distance into the bone from a recently mineralized border was found in the normal and vitamin D-treated groups but was notably absent in the rachitic bones. Microprobe measurements of Ca:P molar ratios in hydroxyapatite standards and in normal rat bone were approximately 1.7. In both rachitic and vitamin D-treated bones, the Ca:P molar ratio was significantly higher than that in normal bones and correlated with serum Ca:P ratios. It is suggested that the increased Ca:P ratios in the rachitic and vitamin D-treated bones may be explained by an increased carbonate deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408618
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of combined and separate intermittent administration of low-dose human parathyroid hormone fragment (1–34) and 17β-estradiol on bone histomorphometry in ovariectomized rats with established osteopenia (1992)
    Springer
    Calcified tissue international 50 (1992), S. 214-220 
    Details
    ISSN: 1432-0827
    Keywords: Ovariectomy ; Osteopenia ; PTH ; Estradiol ; Bone turnover ; Quantitive bone histomorphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To evaluate the potential use of a combination of parathyroid hormone (PTH) and estrogen as therapy for osteoporosis, we examined the effects of combined and separate administration of low-dose PTH and estradiol in ovariectomized rats with established osteopenia. Ovariectomized rats were untreated for 5 weeks after surgery and then injected s.c. with vehicle (Ovx+V), 1–34 hPTH (2.5 μg/kg/day) (Ovx+P), 17β-estradiol (50 μg/kg/day) (Ovx+E), or a combination of these (Ovx+P+E), for a further 4 weeks. We found no differences in serum calcium, tubular reabsorption of phosphate, or 25OHD. 1,25(OH)2D levels were significantly higher in Ovx+P and lower in Ovx+E, when compared with Ovx+V. Though there was no change in bone mineral density (BMD) in the diaphysis region of femurs, reduction of BMD in the distal region of the femurs in Ovx+V was reversed in Ovx+E and Ovx+P+E. Compared with Ovx+V, Ovx+P and Ovx+P+E had significantly higher cancellous bone volume (Cn-BV/TV) whereas Ovx+E showed a nonsignificant increase. When indices of bone turnover were examined, PTH alone showed a small but not significant improvement in bone formation rate (BFR). Increased osteoclast surface (OCS), as the result of ovariectomy, was inhibited in Ovx+E and Ovx+P+E. Estrogen alone (Ovx+E) severely inhibited BFR, but co-administration of PTH and estrogen (Ovx+P+E) showed an impressive reversal of such inhibition. The changes in BFR were mainly derived from changes in double-labeled surface (dLS), except a small increase in mineral apposition rate was also observed in Ovx+P+E. These results suggest that, after extensive cancellous bone loss in the rat tibia, low doses of PTH function anabolically, especially in situations where the bone formation rate is low. A combination of both estrogen and PTH may provide the best treatment for improving bone mass by decreasing resorption and maintaining a high bone formation rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296285
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  • 3
    Electronic Resource
    Electronic Resource
    Mean wall thickness and formation periods of trabecular bone packets in corticosteroid-induced osteoporosis (1983)
    Springer
    Calcified tissue international 35 (1983), S. 410-417 
    Details
    ISSN: 1432-0827
    Keywords: Bone remodeling ; Histomorphometry ; Corticosteroid therapy ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have compared the mean wall thickness (MWT) and active formation periods (sigmaf(A)) of trabecular bone packets in iliac crest biopsies from 20 patients (7 male, 13 female) with corticosteroid-induced osteoporosis (CS-OP) and 20 age- and sex-matched controls. The trabecular bone volume (TBV) of the CS-OP patients (9.6%±2.2% [SD]) was significantly reduced compared to controls (19.3%±5.1%). The MWT of CS-OP patients (32.7±4.3 µm) was also significantly lower than the control value (48.0±6.2 µm). There was a positive correlation between MWT and TBV in both groups. The mineralization rate (M) of the CS-OP patients (0.54±0.25 µm/day) was within the normal range, and since there was no increase in osteoid seam thickness, so therefore was the osteoblastic appositional rate (OAR). The active formation period of trabecular bone packets (sigmaf(A)=MWT/M) was significantly lower in the CS-OP patients (55.9 ± 14.4 days) than in the control group (68.1 ± 9.4 days). MWT and sigmaf(A) both decreased with age in the control group, whereas in the CS-OP group they were independent of age. We conclude that corticosteroid therapy results in a reduction of the MWT of trabecular bone packets and, consequently, of TBV. In these patients, where the OAR was normal, the reduction in MWT was apparently caused by a shortening of the lifespan of the active osteoblastic population at the basic multicellular unit (BMU) level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405069
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  • 4
    Electronic Resource
    Electronic Resource
    Lack of significant effect of carboxyl-terminal parathyroid hormone-related peptide fragments on isolated rat and chick osteoclasts (1995)
    Springer
    Calcified tissue international 57 (1995), S. 47-51 
    Details
    ISSN: 1432-0827
    Keywords: Osteoclast ; Bone resorption ; Parathyroid hormone-related protein ; Calcitonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Parathyroid hormone-related protein (PTHrP) fragments 107–111, 107–138, and 107–139 were all found to be without consistent significant inhibitory effect on the resorptive activity of isolated rat and chick osteoclasts over the dose range 10-13 M-10-9 M. In the rat, these results contrasted with a strong and significant inhibition (100%) by calcitonin. Our results differ from that previously reported for C-terminal fragments of PTHrP by Fenton et al. [1–3], who noted up to a 70% inhibition of resorptive activity of isolated rat or chick osteoclasts at femtomolar doses and greater. It is possible that the lack of response observed in our osteoclast assays is due to unknown variables in the bone slice assay that influence the responsiveness of isolated osteoclasts to these fragments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298996
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  • 5
    Electronic Resource
    Electronic Resource
    Relationships between bone structure in the iliac crest and bone structure and strength in the lumbar spine (1993)
    Springer
    Osteoporosis international 3 (1993), S. 90-96 
    Details
    ISSN: 1433-2965
    Keywords: Bone histomorphometry ; Bone mass ; Cancellous bone structure ; Cancellous bone strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to examine the relationship between histomorphometric variables of cancellous bone structure and ultimate compressive strength (UCS) in the second lumbar vertebra (L2) and to determine whether structural variables in the iliac crest are predictive of the same variables and of UCS in L2. At autopsy, 7.5 mm diameter cores were removed from the iliac crest and from L2 of 29 subjects who had died suddenly without bone disease. Cancellous bone volume (BV/TV, %) was significantly lower in L2 than in iliac crest due to lower trabecular number (Tb.N, per mm) and thickness (Tb.Th, µm). There were significant correlations between iliac crest and L2 for BV/TV, Tb.N and trabecular separation (Tb.Sp, µm), but not for Tb.Th. BV/TV was negatively correlated, and Tb.Sp was positively correlated with age at both sites. Tb.Th was not significantly correlated with age in the iliac crest, but a significant negative correlation was observed in L2. The UCS of vertebral cores was negatively correlated with age. BV/TV and Tb.Th in L2 were positively correlated with UCS in L2. Cortical width and BV/TV in iliac crest were positively correlated with UCS in L2. We conclude that: (1) cancellous bone volume in the iliac crest is higher than in the lumbar spine due to thicker, more closely spaced trabecular plates, (2) the changes in structural variables with age are generally similar in the iliac crest and lumbar vertebra, but trabecular thinning with age is more evident in the spine than in the ilium, and (3) the compressive strength of cancellous bone in the lumbar spine is correlated with histomorphometric variables of bone structure, as measured both in the lumbar spine and in the iliac crest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623379
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of parathyroid hormone secretion in vitro and in vivo (1982)
    Springer
    Calcified tissue international 34 (1982), S. 313-316 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411259
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