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  • 11
    Digitale Medien
    Digitale Medien
    Ipriflavone: New insights into its mechanisms of action on bone remodeling (1993)
    Springer
    Calcified tissue international 52 (1993), S. 151-152 
    Details
    ISSN: 1432-0827
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00308326
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  • 12
    Digitale Medien
    Digitale Medien
    Interactions between ipriflavone and the estrogen receptor (1995)
    Springer
    Calcified tissue international 56 (1995), S. 160-165 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Ipriflavone ; Estrogen receptor ; Osteoclasts ; Bone resorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Estrogen replacement therapy is effective in the prevention of postmenopausal osteoporosis, and a direct action of 17-β-estradiol (17βE2) on osteoblastic and osteoclastic cells has been demonstrated. The inhibition of bone resorption by ipriflavone (IP), an isoflavone derivative devoid of estrogenic properties but active in potentiating the effects of estroge on bone tissue, has been shown in in vitro and in vivo studies and confirmed by clinical data. To investigate the molecular mechanisms that underlie IP effect, we studied the possible interactions of IP and its four main in vivo metabolites (I, II, III, and V) with the estrogen receptor (ER) in the human preosteoclastic cell line FLG 29.1, whose growth and function are modulated by the compound. In parallel experiments, the human breast cancer cell line MCF7 was also analyzed. IP binding sites were demonstrated in the nuclear fraction of FLG 29.1 cells. 17βE2 and other steroid compounds failed to displace IP binding to intact FLG 29.1 cells. Similarly, IP and metabolites I, III, and V were not able to displace 17βE2 binding to intact MCF7 cells, whereas metabolite II showed an IC50 of 61 nM. 17βE2 binding to FLG 29.1 cells was increased after preincubation with metabolites I, III, and V. IP and its metabolites did not induce FR-dependent gene expression in FLG 29.1 and MCF7 cells transfected with a reporter gene and an estrogen response element (ERE). These results suggest that IP effects on osteoclast precursors are not mediated by a direct interaction with the ER, even if a crosstalk between the mechanisms of action of IP and 17βE2 cannot be excluded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00296349
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  • 13
    Digitale Medien
    Digitale Medien
    A Human Homolog of the 150 kD Avian Osteoclast Membrane Antigen Related to Superoxide Dismutase and Essential for Bone Resorption is Induced by Developmental Agents and Opposed by Estrogen in FLG 29.1 Cells (1997)
    Springer
    Calcified tissue international 60 (1997), S. 187 -193 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Key words: Osteoclast — Vitamin D3— Phorbol ester — Osteoblast — Estrogen.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Osteoclast development from hematopoietic bone marrow precursors is associated with the expression of various enzymes, receptors, adhesion molecules, and other specialized components. Among these is a novel 150 kD superoxide dismutase-related membrane glycoprotein, originally identified by its reaction with the anti-osteoclast monoclonal antibody 121F. This antigen is uniquely restricted to osteoclasts in bone, universally present on osteoclasts from multiple species, induced during osteoclast differentiation in vitro and in ovo, and required at high levels for avian osteoclastic bone pit resorption. Expression of a comparable human antigen was investigated using human leukemic FLG 29.1 cells capable of differentiating towards an osteoclast-like phenotype. Phorbol ester, 1,25 (OH)2 vitamin D3, and osteoblast-derived soluble factors elicited dose and time-dependent inductions of this antigen as measured by enzyme-linked immunosorbent assay (ELISA) and immunocytochemical staining, coincident with their display of multiple other osteoclastic features. Synergistic interactions of these modulators led to further elevations in the ultimate expression levels of this antigen, although not to the full extent associated with in vivo-formed avian osteoclasts. The potent antiresorptive hormone 17β-estradiol, but not its inactive α isomer, partially suppressed the phorbol ester-induced elevation of the 121F antibody-reactive antigen in FLG 29.1 cells as it does in avian osteoclast-like cells. Characterization of the human antigen isolated from FLG 29.1 cells by 121F immunoaffinity purification demonstrated that this regulated membrane component was synthesized by these human cells, more abundant following their differentiation into osteoclast-like cells, and similar biochemically and immunologically to the 150 kD integral membrane glycoprotein previously described from avian osteoclasts. Therefore, this report is the first documentation that human osteoclast-like FLG 29.1 cells express, in a developmentally regulated fashion, a homolog of the specific 150 kD avian osteoclast surface antigen that is related to superoxide dismutase, a protective free radical scavenging enzyme and is essential for osteoclastic bone resorption.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002239900212
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  • 14
    Digitale Medien
    Digitale Medien
    Comparison of Quantitative Calcaneal Ultrasound and Dual Energy X-ray Absorptiometry in the Evaluation of Osteoporotic Risk in Children with Chronic Rheumatic Diseases (2000)
    Springer
    Calcified tissue international 67 (2000), S. 19-23 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Key words: Broadband ultrasound attenuation — Contact ultrasound bone analyzer — Bone mineral density — Dual energy X-ray absorptiometry — Chronic rheumatic diseases.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Osteoporosis is a common complication in children with chronic rheumatic diseases (CRD). Although dual energy X-ray absorptiometry (DXA) is increasingly being used to determine bone mineral density (BMD) in children, it exposes the subject to ionizing radiation and does not provide a measure of true bone density; in fact, in growing bones the increase in BMD is mainly caused by the increase in bone size. In recent years, quantitative ultrasound techniques (QUS) have been used in radiation-free assessment of bone density and ``bone quality'' by measurement of the ultrasound waves attenuation by bone (BUA). In the present study we made a direct comparison of BUA in the calcaneum, determined by the pediatric contact ultrasound bone analyzer (CUBA) with lumbar BMD measured by DXA, in a group of 6–18-year-old patients with CRD. The study group consisted of 53 patients affected with juvenile rheumatoid arthritis (n = 29), systemic lupus erythematosus (n = 13), and juvenile dermatomyositis (n = 11). Mean age was 13.02 ± 2.69 years. In 22 patients (19 girls, 3 boys) both DXA and CUBA were repeated after 1 year in order to assess the mean percentage rate of BMD and BUA change over this time. Both lumbar spine BMD and calcaneal BUA measurements were lower in the CRD patients compared with a control group (P 〈 0.001). Calcaneal BUA was significantly correlated (r = 0.83, P 〈 0.001) with lumbar spine BMD. Age and sex correction (Z-score) did not change the relationship between BUA and BMD (r = 0.80, P 〈 0.001). A significant correlation between the mean percentage of variation (Δ%) of BMD and BUA (r = 0.76, P 〈 0.001) was also demonstrated in the 22 patients who were evaluated prospectively. Portability, ease of use, lower cost, and absence of radiation make CUBA a promising means of evaluating BMD in children.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00223001090
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  • 15
    Digitale Medien
    Digitale Medien
    First International Workshop on the Genetics of Bone Disease Davos Congress Centre, Switzerland 17–20 March 2001 (2000)
    Springer
    Calcified tissue international 67 (2000), S. 481-500 
    Details
    ISSN: 1432-0827
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002230001214
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  • 16
    Digitale Medien
    Digitale Medien
    P-glycoprotein is expressed in parathyroid epithelium and is regulated by calcium (1995)
    Springer
    Calcified tissue international 56 (1995), S. 170-174 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Multidrug resistance ; P-glycoprotein ; Parathyroid ; Calcium regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract P-glycoprotein (Pgp), the multidrug resistance (mdr) gene product, has been described in normal tissues with diverse physiologic functions. A broad role as a transporter protein for toxins, hormones, and physiologic metabolites has been provisionally deduced, based on structural analysis and immunoanatomic localization. Recently, significant levels of Pgp have been demonstrated in endocrine and hormonally responsive tissues and tumors. We examined calcium-regulated, clonal parathyroid epithelial (PT-r) and endothelial cells (BPE-1) and frozen parathyroid tissue from normal human parathyroid, parathyroid hyperplasia, parathyroid adenoma, and parathyroid carcinoma for expression of the multidrug resistance gene (Mdr1) and Pgp utilizing Northern and Western analysis and immunohistochemistry. We also investigated the effect of extracellular calcium (eCa) on Pgp expression in PT-r cells at the molecular/cellular level. Immunohistochemistry, utilizing three murine monoclonal antibodies (MAbs)—C494, JSB-1, and C219—which recognize spatially distinct cytoplasmic epitopes of Pgp, revealed strong immunoreactivity in PT-r cells, normal parathyroid, and parathyroid hyperplasia, and weak immunostaining in parathyroid adenomas. BPE-1 cells, endothelial cells, and parathyroid carcinoma were negative. PT-r cells showed a single 130 kDa band (120 KDa after glycosidase treatment) on Western blot and a 4.6 kb transcript on Northern analysis, consistent with Pgp. Western and Northern blot analysis of PTr cells cultured in different eCa concentrations showed that eCa up-regulated Pgp expression. Northern analysis of doxorubicin-resistant human breast carcinoma cells (Adr1) (MCF-7) exhibited constitutive expression of Pgp mRNA without modifications, with increasing eCa concentrations. We conclude that N-glycosylated Pgp is expressed in parathyroid epithelial cells and that calcium responsiveness of Pgp expression appears cell specific.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00296351
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  • 17
    Digitale Medien
    Digitale Medien
    Vitamin D Receptor Genotypes and Intestinal Calcium Absorption in Postmenopausal Women (1997)
    Springer
    Calcified tissue international 61 (1997), S. 460-463 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Key words: VDR genotypes — Intestinal Ca absorption — Osteoporosis genetics — Strontium chloride — Postmenopausal women.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Several studies have shown that bone mass and bone turnover are genetically determined. This genetic component is thought to be mediated in part by polymorphisms at the vitamin D receptor (VDR) locus, even though the underlying molecular mechanisms are still unknown. To evaluate a possible site of differential action of the VDR gene alleles we examined their correlation with intestinal calcium absorption in 120 Caucasian postmenopausal women (aged 61 ± 0.6 years). VDR gene polymorphisms for Apa I, Bsm I, and Taq I restriction endonucleases were assessed by Southern blotting analysis. The most common genotypes observed in our population were AaBbTt (37%), AABBtt (20%), aabbTT (15%), AabbTT (15%), and AABbTt (9%). Although there was some evidence of 13% higher lumbar BMD values in aabbTT genotype with respect to AABBtt genotype, this difference of approximately 0.1 g/cm2 did not reach statistical significance, possibly because of the limited number of observations. On the contrary, no relationship was found between genotypes and femoral neck BMD values. Intestinal calcium absorption was significantly lower in BB and tt genotypes than, in bb and TT genotypes, respectively, and in AABBtt genotype than in either aabbTT or AaBbTt genotypes (P= 0.0015 ANOVA). No significant differences in intact PTH, alkaline phosphatase, 25OHD3, and 1,25(OH)2D3 were found among subjects with different VDR genotypes. These results are consistent with a possible role of VDR alleles on intestinal calcium absorption.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002239900368
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  • 18
    Digitale Medien
    Digitale Medien
    Natural and Synthetic Isoflavones in the Prevention and Treatment of Chronic Diseases (1997)
    Springer
    Calcified tissue international 61 (1997), S. S005 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Key words: Isoflavones — Phytoestrogens — Chronic diseases.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. The evidence that natural isoflavones protect against several chronic diseases is both observational and experimental. In humans, epidemiologic findings clearly show a higher incidence of some common types of cancer (i.e., breast, prostate, and colon) and of coronary heart diseases in Western populations exposed to limited amounts of soybean isoflavones (i.e., genistein, daidzein) in the diet. Further evidence for cancer and cardiac protection and antiatherogenic effects resulting from soybean isoflavones administration has been noted in various experimental animal models. Isoflavones may also prevent postmenopausal bone loss and osteoporosis. In fact, genistein has been reported to be as active as estrogens in maintaining bone mass in ovariectomized rats. Moreover, the synthetic isoflavone derivative ipriflavone is able to reduce bone loss in various types of animal models of experimental osteoporosis providing a rationale on its use in the prevention and treatment of postmenopausal and senile osteoporosis in humans. The mechanism through which isoflavones may exert the above-mentioned effects seems to depend, at least in part, on their mixed estrogen agonist-antagonist properties. An alternative hypothetical mechanism could derive from other biochemical actions of isoflavones such as inhibition of enzymatic activity, in particular protein kinases, or activation of an ``orphan'' receptor distinct from the estrogen type I receptor.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002239900376
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  • 19
    Digitale Medien
    Digitale Medien
    Glucocorticoid-induced osteoporosis in the lumbar spine, forearm, and mandible of nephrotic patients: A double-blind study on the high-dose, long-term effects of prednisone versus deflazacort (1992)
    Springer
    Calcified tissue international 50 (1992), S. 490-497 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Deflazacort-Forearm ; lumbar ; mandibular BMC-Nephrotic syndrome-Prednisone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The long-term effects of high dose steroid treatment with either prednisone (PDN) or deflazacort (DFZ) were examined on various parts of the skeleton in 29 patients with nephrotic syndrome. All had normal skeleton at the start of the steroid treatment. At the beginning, PDN was given as 80 mg/day and tapered down to 20 mg/day for 1 year and DFZ was given in an equipotent dosage. Twenty-three patients completed 6 months of treatment, and 18 patients completed 12 months of treatment. Beside laboratory parameters to ensure the effect of treatment on the nephrotic syndrome, all had measurements of the bone mineral content (BMC) at 0, 6, and 12 months of treatment. BMC was measured by single photon absorptiometry of both forearms and by dual photon absorptiometry of the mandible, forearms, and lumbar spine. The effect of DFZ was compared to that of PDN due to a potential “calcium sparing” effect of DFZ. The therapeutical effects on the nephrotic syndrome were not different between the two drugs. Urinary 24-hour protein decreased from 9.9 to 1.1 g in the DFZ-treated patients and from 8.0 to 1.4 g in the PDN-treated patients. Plasma albumin concentration normalized in both groups. Both groups of steroid-treated patients had a significant reduction of the BMC levels in all parts of the skeleton. However, the bone decay rates per month were significantly different between different bone regions and between different drug regimes. In the forearm, the bone decay rate was 5.3%/year in the PDN group and 2.0%/year in the DFZ group (P〈0.001). In the mandible, decay rate was 7.0%/year in both groups, and in the lumbar spine it was 12.5%/year in the PDN group and 6.8%/year in the DFZ group (P〈0.01). Thus, the bone loss in the PDN-treated group was significantly higher than that of the DFZ-treated patients, despite a similar therapeutical effect on the nephrotic syndrome. Therefore, the detrimental effect of long-term steroid treatment on the skeleton may not be abolished, but can be reduced significantly by using deflazacort instead of prednisone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00582160
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  • 20
    Digitale Medien
    Digitale Medien
    Absence of Correlation Between BMP-4 Polymorphism and Postmenopausal Osteoporosis in Italian Women (2000)
    Springer
    Calcified tissue international 67 (2000), S. 93-94 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Key words: Osteoporosis — BMP-4 — Genetic association — SNP.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Several studies have demonstrated that bone has the power of regeneration and repair. BMPs (bone morphogenetic proteins) are involved in the determination of osteoblast phenotype and bone turnover, therefore genes coding for these proteins, like BMP-4, could be considered potential candidate genes for osteoporosis. We investigated the association of BMP-4 gene polymorphism with osteoporosis in a cohort of 72 osteoporotic, postmenopausal women and 82 unrelated controls. We failed to detect any significant association between this genetic marker and the disease.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s00223001103
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