ISSN:0884-0431    

DOI:10.1002/jbmr.5650050102

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050103

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThe major conclusion of this study is that the different laboratory assays for serum BGP give a reasonably consistent picture of bone metabolism in the metabolic bone diseases examined only if the results are expressed as a percentage of serum BGP levels in normal individuals. This requires that all laboratories establish a mean control serum BGP value in an appropriate population of normal individuals. Since BGP levels determined by different laboratories on the same serum sample can vary by more than fourfold, the absolute serum BGP levels determined in one laboratory cannot be compared directly with the serum BGP levels determined in another. Although we cannot comment on the efficacy of different laboratory assays for serum BGP as measures of bone metabolism in disease states that were not examined, such as osteoporosis, it is clear that the large differences between laboratory assays make it imperative that all interlaboratory comparisons be based on values expressed as a percentage of serum BGP in an appropriate population of normal individuals

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050104

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractStudies were performed to investigate vitamin D metabolism in Mexican‐Americans. Groups of 15 whites and 16 Mexican‐Americans ranging in age from 18 to 41 years were evaluated. All of them were within 25% of their ideal body weight. Each of them was admitted to the Clinical Research Center of the University of Texas Health Science Center and placed on a daily diet estimated to contain 400 mg calcium and 900 mg phosphate. It was found that whereas serum vitamin D (1.8 ± 0.5 versus 7.6 ± 1.3 ng/ml,P<0.001) and serum 25‐hydroxyvitamin D (9 ± 1 versus 17 ± 2 ng/ml,P<0.01) were significantly lower and serum 1,25‐dihydroxyvitamin D (37 ± 2 versus 28 ± 2 pg/ml,P<0.001) was significantly higher in the Mexican‐Americans than in the whites, serum calcium (9.1 ± 0.1 versus 9.2 ± 0.1 mg/dl), magnesium (1.84 ± 0.07 versus 1.80 ± 0.07 mEq/liter), and Gla protein (19 ± 3 versus 21 ± 2 ng/ml) were not different in the two groups. Urinary calcium (144 ± 14 versus 124 ± 16 mg/day), phosphate (672 ± 51 versus 683 ± 44 mg/ day), sodium (110 Ω 8 versus 99 ± 9 mEq/day), potassium (43 ± 4 versus 49 ± 3 mEq/day), and magnesium (7.3 ± 0.7 versus 7.7 ± 0.5 mEq/day) and creatinine clearance (173 ± 14 versus 154 ± 7 liters/day) were not different in the two groups. Serum immunoreactive PTH (390 ± 25 versus 299 ± 21 pg/ml, P<0.02) was significantly higher in the Mexican‐Americans than in the whites and urinary cyclic AMP (2.64 Ω 0.27 versus 2.59 ± 0.39 nM/dl GF) was not different in the two groups. The results indicate that Mexican‐Americans are depleted of vitamin D and, as a result, have low serum 25‐hydroxyvitamin D and compensatory increases in serum immunoreactive PTH and 1, 25‐dihydroxyvitamin D. The depletion of vitamin D in Mexican‐A

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050105

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractNeovascularization across a gap defect in a rabbit tibial cortex was monitored using the optical bone chamber implant (BCI). Cortical bone growing by apposition as trabeculae was observed weekly as it penetrated a slit into a tissue space in vivo and in situ. Each rabbit was viewed weekly with an intravital microscope from 3 to 8 weeks postimplantation. The constant field of view was the slit‐gap tissue space, which was 100 μm thick and 2 mm in diameter. Vessels were imaged with epi‐illuminated fluorescence microscopy as they carried FITC‐dextran 70 that had been injected into an aural vein. Observations were videotaped and photographed. Videotape frames were analyzed with a digital image processing system to obtain measures of vessel length per unit volume (L/V) of fibroblastic granular tissue and trabeculae, caliber C, and flow velocityu, all as functions of time.Observations supported the conclusions that (1) neovascularization precedes neo‐osteogenesis, (2) major vessels tend to align with the tibial axis, (3) bone apposition‐generated destruction of fibrous granular tissue vessels stimulates fibrous granular tissue angiogenesis, which keeps itsL/Vconstant, (4)L/Vin trabeculae increases with time, and (5) blood supply (Q̄) and nutrient exchange in healing trabeculae are not positively correlated. Thus, O2supply to the trabeculum cannot be predicted from Q̄ alone because the nutrient exchange area is not constant. It was noted that an increase in the potential nutrient exchange area occurred in both fibrous granular tissue and osseous vessels and the volume fraction of blood decreased in the fibrous granular tissue and remained constant in t

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050106

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThe bisphosphonates 4‐amino‐1‐hydroxybutylidene‐1, 1‐bisphosphonic acid (ABP), 3‐amino‐1, 1‐hydroxypropane‐1, 1‐diphosphonic acid (APD), and 1‐hyroxyethane‐1, 1‐diphosphonic acid (EHDP) were compared for their ability to inhibit the osteoclastic resorption of bone in culture. This was achieved by measuring the effect of bisphosphonate concentration on the number of resorption pits formed and the total area of resorption. During this analysis, a new application of reflected polarized light microscopy was developed that has advantages over other microscopy techniques, including scanning electron microscopy (SEM), as applied to the analysis of resorbed bone surfaces. Based on area analysis, the bisphosphonates were effective for the range 10−7–10−8M, with ABP about two to five times more effective than EHDP or APD. Similar data were obtained by counting the number of resorption pits but with EC5010 times higher. At lower concentrations (10−9M), bisphosphonates may enhance the formation of resorption pits. APD was found to be more toxic (10 times) than ABP or EHDP to osteoclasts and mononuclear cells, but toxic concentrations were at least 102times higher than the resorption EC50. These data plus immunofluorescence, SEM, and transient incubation experiments show that it is the bisphosphonate‐bone complex that directly inhibits the excavation of resorption pits by mature osteoclasts. The mechanism of action does not appear to require inhibition of osteoclast differentiation or toxic elimination of osteoclasts. Bisphosphonates, however, subtly af

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050107

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractIn aging and in osteoporosis, decreased bone density is associated with decreased bone mass. However, changes in the bone mineral phase remain a matter for investigation. In particular, it is unknown whether bone mineral loss is directly related to reduction in bone mass or associated with changes in the concentration of mineral elements in mineralized bone tissue. In this study, the cortical bone concentration of elements was determined in biopsies of the ilium from 33 subjects (12 controls and 21 individuals with untreated severe osteoporosis). Calcium and phosphorus concentrations were evaluated in cortical and trabecular bone using energy‐dispersive x‐ray (EDX) microanalysis and inductively coupled plasma optical emission spectrometry (ICPOES). Bone concentrations of Na, K, Mg, Cu, Zn, Fe, Sr, Al, B, and Si were also determined in cortical bone using ICPOES. Additionally, the concentration of F in cortical bone was measured with a specific ion electrode and the concentration of Pb was determined by atomic absorption spectrometry. In mineralized bone tissue there was no significant age‐dependent variation in the concentration of Ca, P, or other elements either in controls or in osteoporotic subjects. Moreover, the concentration of elements in bone tissue did not differ in the two groups. These results suggest that the decrease in bone density in osteoporosis is directly related to evolution of the bone mass, without detectable changes in the concentration of elements i

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050108

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTransforming growth factor ß (TGF‐ß) is a 25 kD multifunctional polypeptide with pronounced effects on the proliferation and differentiation of a variety of cells in vitro. TGF‐ß is a potent regulator of the activity of cells with the osteoblast phenotype and of isolated osteoclasts. It is released in increased amounts by bone cultures stimulated to resorb. Organ cultures of neonatal mouse calvaria produce TGF‐ß as an inert large‐molecular‐weight complex that must be dissociated to release biologically active TGF‐ß (5‐8 ng/ml). We have shown recently that stimulated isolated avian osteoclasts release active TGF‐ß from this bone‐derived biologically latent form. In this report we have characterized this bone latent form of TGF‐ß. Only small amounts of active TGF‐ß (<0.5 ng/ml) and no free binding protein are detectable in conditioned medium from bone cultures. Active TGF‐ß can be detected in acid‐treated calvarial conditioned media in which none or only minute amounts could previously be detected. Following incubation at 37°C, this activated TGF‐ß gradually loses activity. Cross‐linking studies using125I‐labeled TGF‐ß show that this loss of activity is due to TGF‐ß binding to a protein of approximately 300 kD. The TGF‐ß latent complex accumulates in a linear manner and is stable in the presence of serum and the protease trypsin. Increases in temperature and pH extremes dissociate the complex to release active TGF‐ß. Decreases in pH result in an exponential increase in TGF‐ß activity. Significant activation of the latent TGF‐ß was detectable at pH values as high as 4 and 5. Since the osteoclastic microenvironment is acidic during bone resorption, these data suggest that this acidic microenvironment may regulate TGF

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050109

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractAluminum administration in the experimental animal results in osteomalacia as characterized by osteoid accumulation and decreased mineralization. Previous in vivo and in vitro studies have indicated that either aluminum directly inhibits mineralization or is toxic to the osteoblast. In the present study, PTH was continuously infused in rats with aluminum‐induced osteomalacia to evaluate whether aluminum administration decreased mineralization without a concomitant decrease in osteoblasts. Four groups of rats were studied: chronic renal failure (CRF); CRF + aluminum (AL); CRF + PTH; and CRF + PTH + AL. Rats were sacrificed 5 and 12 days after aluminum or diluent administration; in the PTH groups, bovine PTH (1–34) was administered at 2 units/h via a subcutaneously implanted Alzet pump. Aluminum administration decreased osteoblast surface, increased osteoid accumulation, and produced a cessation of bone formation. The infusion of PTH alone increased osteoblast surface and bone formation. The simultaneous administration of aluminum and PTH resulted in an osteoblast surface intermediate between aluminum and PTH alone; however, despite a PTH‐induced restoration of osteoblast surface, bone formation did not increase. These findings indicate (1) aluminum is toxic to osteoblasts and also directly inhibits mineralization even when osteoblasts are not decreased; (2) PTH is capable of increasing osteoblasts even in the presence of aluminum; and (3) despite a PTH‐induced increase in osteoblast surface, mineralization of osteoid was not

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050110

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTo determine if parathyroid hormone (PTH) is essential for lactation in rats, the parathyroid glands were removed surgically during the first week of lactation and the rats were given a diet containing a high calciumphosphorus ratio to maintain a normal serum calcium concentration. Lactating rats were placed on diet containing 1.2% calcium (Ca) and 0.8, 0.6, or 0.4% phosphorus (P) on day 2 postpartum (PP) and were parathyroidectomized (PTX) at 4–6 days PP. At 10 days PP serum Ca was 10.5 ± 0.2 mg/dl (mean ± SEM) for PTX rats and 10.4 ± 0.3 mg/dl in sham‐operated lactating rats when the diet contained 0.6% P. When the diet P was 0.8%, the litters gained little or no weight and serum Ca fell to 6.9 ± 0.6 mg/dl by day 10 PP in PTX rats compared with 10.2 ± 0.2 mg/dl in sham rats. PTX rats fed the diet containing 1.2% Ca and 0.6% P maintained a normal serum Ca level until at least day 18 PP, but their serum P levels fell gradually from approximately 5 mg/dl at 10 days to 3 mg/dl at 18 days PP. In spite of this hypophosphatemia, the litters of PTX and sham rats had gained the same amount of weight by age 16 days, indicating equal milk production in the two groups. Milk Ca, P, and total solids were not significantly different between PTX and sham rats on day 11 PP. With the 1.2% Ca and 0.4% P diet, the femurs lost approximately 20% of dry bone mass in both PTX and sham rats (p<0.01) between 5 days PP, when PTX was carried out, and 20 days PP. We conclude that the absence of the parathyroid glands does not affect milk production, milk mineral composition, or the lactation‐associated bone loss when normal serum Ca levels are maintained by diet. We suggest that PTH is not essential for lactation beyond its normal function of maintaining the serum Ca co

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050111

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY