Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MINERALS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55Linked to original sources
PubMed2003

Decorin modulates matrix mineralization in vitro.

Decorin (DCN), a member of small leucine-rich proteoglycans, is known to modulate collagen fibrillogenesis. In order to investigate the potential roles of DCN in collagen matrix mineralization, several stable osteoblastic cell clones expressing higher (sense-DCN, S-DCN) and lower (antisense-DCN, As-DCN) levels of DCN were generated and the mineralized nodules formed by these clones were characterized. In comparison with control cells, the onset of mineralization by S-DCN clones was significantly delayed; whereas it was markedly accelerated and the number of mineralized nodules was significantly increased in As-DCN clones. The timing of mineralization was inversely correlated with the level of DCN synthesis. In these clones, the patterns of cell proliferation and differentiation appeared unaffected. These results suggest that DCN may act as an inhibitor of collagen matrix mineralization, thus modulating the timing of matrix mineralization.

Animals↗
PubMed1997

Serum vitamin K level and bone mineral density in post-menopausal women.

OBJECTIVE: Vitamin K is known to influence bone metabolism by facilitating the synthesis of osteocalcin (BGP). The bone mineral density decreases drastically after menopause. We investigated the relationship of bone mineral density, vitamin K levels and other biological parameters of bone metabolism in post-menopausal women. METHODS: Serum levels of vitamin K, BGP and other markers of bone metabolism were measured in 71 post-menopausal women (19 with reduced bone mineral density and 52 with normal bone density), and 24 women with climacteric symptoms receiving hormone replacement therapy (HRT), (6 with reduced bone mineral density and 18 with normal density). RESULTS: In the first group, women with reduced bone mineral density showed lower levels of vitamin K1 and K2 than those with normal bone mineral density. In the other group, the level of BGP decreased but levels of vitamin K showed no increase during HRT. CONCLUSION: The present findings suggested that vitamin K was related to post-menopausal bone mineral loss.

Bone Density↗
PubMed1999

Why does intermittent hydrostatic pressure enhance the mineralization process in fetal cartilage?

The purpose of this study was to determine which factor is the most likely one to have stimulated the mineralization process in the in vitro experiments of Klein-Nulend et al. (Arth. Rheum., 29, 1002-1009, 1986), in which fetal cartilaginous metatarsals were externally loaded with an intermittent hydrostatic pressure, by compressing the gas phase above the culture medium. Analytical calculations excluded the possibility that the tissue was stimulated by changes in dissolved gas concentration, pH or temperature of the culture medium through compression of the gas phase. The organ culture experiments were also mechanically analyzed using a poroelastic finite element (FE) model of a partly mineralized metatarsal with compressible solid and fluid constituents. The results showed that distortional strains occurred in the region where mineralization proceeded. The value of this strain was, however, very sensitive to the value of the intrinsic compressibility modulus of the solid matrix (Ks). For realistic values of Ks the distortional strain was probably too small (about 2 microstrain) to have stimulated the mineralization. If the distortional strain was not the factor to have enhanced the mineralization process, then the only candidate variable left is the hydrostatic pressure itself. We hypothesize that the pressure may have created the physical environment enhancing the mineralization process. When hydrostatic pressure is applied, the balance of the chemical potential of water across cell membranes may be disturbed, and restored again by diffusion of ions until equilibrium is reached again. The diffusion of ions may have contributed to the mineralization process.

Animals↗
PubMed1994

Vitamin D metabolism and bone mineralization in children with juvenile rheumatoid arthritis.

OBJECTIVE: To examine bone mineralization and bone mineral content in a cross-sectional population of children with juvenile rheumatoid arthritis (JRA). METHODS: Bone mineral content was measured by single-photon absorptiometry in 44 children with JRA and 37 control children. Serum concentrations of minerals, vitamin D, parathyroid hormone, osteocalcin, bone alkaline phosphatase, and tartrate-resistant acid phosphatase, and urinary concentrations of minerals, were determined. RESULTS: Bone mineral content was decreased in children with JRA. Significantly lower concentrations of osteocalcin (7.4 +/- 3.4 vs 12.5 +/- 2.5 micrograms/L) and bone alkaline phosphatase (78.8 +/- 36.4 vs 123.0 +/- 46.0 IU/L) suggested reduced bone formation; lower levels of tartrate-resistant acid phosphatase (10.3 +/- 4.1 vs 14.4 +/- 5.8 IU/L) and a lower urinary calcium/creatinine ratio (0.07 +/- 0.06 vs 0.12 +/- 0.09) suggested decreased bone resorption. The serum calcium concentration was significantly lower (9.3 +/- 1.0 vs 10.0 +/- 0.4 mg/dl), as was the parathyroid hormone concentration (19.8 +/- 8.6 vs 26.7 +/- 9.3 ng/L); 1,25-dihydroxyvitamin D values (30.1 +/- 10.5 vs 30.4 +/- 9.3 pg/ml) were normal. CONCLUSION: These data suggest that decreased mineralization in JRA is related to low bone turnover; parathyroid hormone and 1,25-dihydroxyvitamin D levels may be inappropriately normal for the decreased serum calcium concentration in children with JRA.

Adolescent↗
PubMed2000

Effect of non-weight-bearing body fat on bone mineral density before and after menopause.

OBJECTIVE: To investigate the difference in the effect of non-weight-bearing body fat mass on bone mineral density between premenopausal and postmenopausal women. METHODS: We studied 252 regularly menstruating premenopausal women and 213 postmenopausal women with right side dominance. Age, years since menopause (in postmenopausal women), height, weight, and body mass index were recorded. Bone mineral density of non-weight-bearing sites (ie, arms), weight-bearing sites (ie, lumbar spine including L2-4 and legs), and body fat mass were measured by whole-body scanning with dual-energy x-ray absorptiometry. Body fat mass was also measured by dual energy x-ray absorptiometry. RESULTS: Body fat mass did not differ between groups. In postmenopausal women, body fat mass correlated positively with bone mineral density of the left leg (r =. 41, P <.001), right leg (r =.36, P <.001), left arm (r =.31, P <. 001), and lumbar spine (r =.27, P <.001). The correlation between body fat mass and bone mineral density of the left arm remained significant after adjusting for age, years since menopause, and height. In premenopausal women, body fat mass correlated positively with bone mineral density of left leg (r =.37, P <.001) and right leg (r = 0.31, P <.001), but correlated weakly with bilateral arms (r < or =.19) and lumbar spine bone mineral density (r = 0.13, P <.05). CONCLUSION: The effect of non-weight-bearing body fat on bone mineral density was greater in postmenopausal than premenopausal women.

Absorptiometry, Photon↗
PubMed2003

Solubilization and mineralization of polycyclic aromatic hydrocarbons by Pseudomonas putida in the presence of surfactant.

The solubilization and mineralization of polycyclic aromatic hydrocarbons (PAHs) in a soil system amended with different surfactants was examined. Mineralization experiments were conducted with the addition of [14C]pyrene. An inoculum of the PAH-degrading microorganism, Pseudomonas putida, was investigated for its sensitivity towards four non-ionic and one anionic surfactants with different polyoxyethylene (POE) chain lengths. The addition of surfactant was found to enhance the bioavailability of naphthalene, phenanthrene and pyrene with efficiencies ranging from 21.1 to 60.6%, 33.3 to 62.8% and 26.8 to 70.9%, respectively. The enhanced efficiency followed the order of Brij 30, Triton X-100, Tween 80, and Brij 35, which is correlated with the polyoxyethylene chain of the surfactants. Brij 35 and Tween 80 inhibited the growth of P. putida. However, microorganisms can utilize Triton X-100 and Brij 30 as the sole carbon and energy sources at concentrations above CMC values. In the aqueous system without the addition of surfactants, microorganisms could mineralize [14C]pyrene to 14CO(2) which corresponds to 28% of mineralization. The addition of surfactants decreased the mineralization rate of pyrene. Also, the fraction of the micellar-phase pyrene that can be directly biodegraded decreased as the concentration of micelle increases. However, the mineralization rate can be enhanced by the amendment of Brij 30 when soil was applied to the cultures. This suggests that biodegradable surfactants can be applicable for increasing the bioavailability and mineralization of PAHs in soil systems.

Biological Availability↗
PubMed1997

Influence of weight and gonadal status on total and regional bone mineral content and on weight-bearing and non-weight-bearing bones, measured by dual-energy X-ray absosorptiometry.

OBJECTIVE: To evaluate the influence of weight on total body bone mineral content (BMCTB) and regional body bone mineral content (head, arms, trunk and legs). This was studied in accordance with gonadal status and the weight-bearing or non-weight-bearing status of each region. METHODS: The study included 94 postmenopausal women (mean age 60.6 +/- 10.5 years), 36 perimenopausal women (mean age 49.0 +/- 2.3 years) and 60 premenopausal women (mean age 36.1 +/- 6.9 years). Full-body bone densitometry (DXA), for measuring total body bone and regional bone mineral content, was carried out in all the women. RESULTS: Among these groups, the influence of 1 kg of body weight on total and regional bone mineral content (percent) did not differ (paired test P ns). In the overall group of women, paired comparison showed differences between the head and other zones measured (P = 0.036-0.004). In the overall group of women, no differences were found in the percent influence of 1 kg body weight on bone mineral content in any study zone (by ANOVA, Fisher's PLSD post hoc test and the Kruskal-Wallis test). In the overall group of women, Fisher's r to z test revealed a non-significant relationship between weight and the bone mineral content of the head (r = 0.49, P ns) but in every other region the relationship between weight and bone mineral content was significant (r = 0.36-0.54, P < 0.0001 in all). CONCLUSIONS: The effect of body weight on BMCTB and regional did not differ significantly with either gonadal status or weight-bearing (legs) and non-weight-bearing bones (arms).

Absorptiometry, Photon↗
PubMed2003

Bone mineral density and mortality in women and men: the NHANES I epidemiologic follow-up study.

PURPOSE: We sought to assess the long-term association of bone mineral density with total, cardiovascular, and non-cardiovascular mortality. METHODS: The First National Health and Nutrition Examination Survey data were obtained from a nationally representative sample of non-institutionalized civilians. A cohort aged 45 through 74 years at baseline (1971-1975) was observed through 1992. Subjects were followed for a maximum of 22 years. Included in the analyses were 3501 white and black subjects. Death certificates were used to identify a total of 1530 deaths. RESULTS: Results were evaluated to determine the relative risk for death per 1 SD lower bone mineral density, after controlling for age at baseline, smoking status, alcohol consumption, history of diabetes, history of heart disease, education, body mass index, recreational physical activity, and blood pressure medication. Bone mineral density showed a significant inverse relationship to mortality in white men and blacks, but did not reach significance in white women. Based on 1 SD lower bone mineral density, the relative risk for white men was 1.16 (95% confidence interval (CI), 1.07-1.26, p<.01), while for white women the relative risk was 1.10 (95% CI, 0.99-1.23, p=.07), and in blacks the relative risk was 1.22 (95% CI, 1.05-1.42, p<.01). Bone mineral density was also associated with non-cardiovascular mortality in all three race-gender groups. An association between bone mineral density and cardiovascular mortality was found only in white men. CONCLUSIONS: Bone mineral density is a significant predictor of death from all causes (white men, blacks), cardiovascular (white men only) and other causes combined, in whites and blacks.

Aged↗
PubMed2000

Alendronate increases bone strength by increasing the mean degree of mineralization of bone tissue in osteoporotic women.

The mean degree of mineralization of bone (MDMB) was measured by quantitative microradiography on transiliac bone biopsies taken from 53 postmenopausal osteoporotic women who had been treated with alendronate (ALN; 10 mg/day) during 2 (9 patients) or 3 years (16 patients) or with placebo (PLA; 15 and 13 patients, respectively). In the same patients, bone mineral density (BMD) values were obtained by dual-energy X-ray absorptiometry of the lumbar spine and femoral neck at the beginning and end of treatment. Histomorphometric parameters and activation frequency of new remodeling units were also measured on the iliac biopsies. After 2 years of ALN, MDMB in compact bone was 9.3% (p = 0.0035) and in cancellous bone was 7.3% (p = 0.0009) higher, respectively, than PLA. After 3 years of ALN, MDMB in compact bone was 11.6% (p = 0.0002) and in cancellous bone was 11.4% (p = 0.0001) higher, respectively, than PLA. After 2 and 3 years of ALN, and compared with the corresponding PLA, the distribution of the degree of mineralization in compact and cancellous bone showed a clear shift toward the highest mineralization values and a decrease in the number of bone structure units having low values of mineralization. The between-group differences in MDMB were similar to those of BMD at the lumbar spine BMD (+8.7% after 2 years and +9.6% after 3 years, respectively), suggesting that MDMB augmentation probably accounted for the majority of the increase in BMD seen with ALN. The data support the hypothesis that the reduction in activation frequency caused by the antiresorptive effect of ALN is followed by a prolonged secondary mineralization that increases the percentage of bone structure units having reached a maximum degree of secondary mineralization and, through this mechanism, MDMB. That these effects contribute to improved bone strength is demonstrated by the reduction in fracture incidence previously demonstrated in these patients.

Absorptiometry, Photon↗
PubMed2001

Homocysteine decreases chondrocyte-mediated matrix mineralization in differentiating chick limb-bud mesenchymal cell micro-mass cultures.

The differentiating chick limb-bud mesenchymal cell micro-mass culture system has been used as a model for monitoring the effects of matrix modification on cell-mediated calcification. In this study, we show that treating these micro-mass cultures with homocysteine (Hcys) impairs cartilage calcification. Cultures were treated from day 2 to day 7 with two nonphysiological concentrations of Hcys equivalent to 100x and 1000x avian serum levels (0.36 and 3.6 mmol/L), and from days 9-13 with one tenth the concentration. Mineralization assays were done at days 16, 19, and 21, and matrix and cell properties were examined between days 5 and 21. Mineral accretion, based on differential (45)Ca uptake (mineralizing minus control cultures), was significantly reduced in the high-Hcys-concentration group, and slightly reduced in the low-Hcys-concentration group. Electron microscopy at culture day 21 showed that the collagen matrix was less abundant and its banding pattern less obvious in the Hcys-treated groups than in the untreated cultures. Pyridinoline (Pyr) and deoxypyridinoline (d-Pyr) contents were not detectable in day 21 cultures with either 0.36 or 3.6 mmol/L homocysteine, whereas values in mineralizing and nonmineralizing controls ranged from 0.06 to 0.08 and 0.03 to 0.06 (moles/mole collagen) for Pyr and d-Pyr, respectively. Fourier transform infrared (FTIR) imaging also indicated a decreased content of pyridinoline cross-links. Hcys caused other matrix changes as well. Whereas at culture day 5 there was no significant difference in the number of chondrocyte nodules formed, by day 11 the proteoglycan content (measured by Alcian blue dye binding at 595 nm) was significantly reduced in both mineralizing and control cultures in the high- and low-Hcys groups. In contrast, there were no detectable differences in type X collagen and alkaline phosphatase staining in the mineralizing cultures with or without Hcys supplements. Because vital dye stains and electron microscopy studies indicated that cells in the control and experimental groups did not differ in terms of viability, the observed differences cannot be attributed to toxicity. Thus, Hcys treatment, which causes matrix disorganization, decreases the ability of the matrix to support mineralization.

Animals↗
PubMed2002

Lower extremity muscle strength does not independently predict proximal femur bone mineral density in healthy older adults.

The relationship described in the published literature between muscle strength and bone mineral density of older adults is not entirely certain. It is possible that the direct relationship reported in some studies is biased by failing to mathematically account for the biological influence of body weight and body height on both bone mineral density and muscle strength. This study sought to determine if the relationships between measures of lower extremity muscle strength and bone mineral density of the proximal femur are independent of body size (i.e., body height and body weight) in healthy older adults. We recruited 50 older women and 29 older men, all of whom were healthy community dwellers and not involved in resistance training. Quantitative analysis of the isometric strength of the bilateral ankle, knee, and hip joints and assessment of bone mineral density of the proximal femur were conducted. Muscle strength values were adjusted for the influence of body height and body weight using an allometric scaling procedure. The correlations between proximal femur bone mineral density and the unadjusted strength values were weak but statistically significant. After adjusting muscle strength to account for the influence of body height and body weight, the magnitudes of the correlations between bone mineral density and muscle strength diminished substantially and were not significantly different from zero. The results reveal that, for a typical sample of healthy older adults not involved in resistance training, the relationship between maximal isometric muscle strength of lower extremity joints and proximal femur bone mineral density is reliant on body size.

Aged↗
PubMed1996

Expression of matrix proteins during the development of mineralized tissues.

The specific properties of mineralized tissues are defined by the composition of the fraction of the noncollagenous matrix proteins. Because these proteins play a pivotal role in the processes of cell differentiation and activation and of mineralization, their temporal and spatial expression is tightly regulated. Within this study, the expression of the enamel protein amelogenin and of the bone matrix proteins osteopontin, bone sialoprotein, osteocalcin, and osteonectin was investigated by in situ hybridization. Two models that allow observation of the formation of mineralized tissues were chosen. The development of bone and cartilage was observed on murine metatarsals from 15-day-old embryos up to 1-day-old mice. This time covers the periods of initial bone formation as well as onset of resorption of mineralized cartilage and bone. To study gene expression in the mineralized tissues of the dental organ, enamel, dentin, and cementum, developing molars ranging in age from 16-day-old embryos to 14 days after delivery were chosen. Within this time frame, the molars develop from an immature state to the differentiated organ which erupts through the mandibular bone. In the developing metatarsals, osteopontin and bone sialoprotein mRNAs were detected in osteoblasts and hypertrophic chondrocytes at the onset of mineralization. In the tooth organ, only cementoblasts expressed transcripts encoding the two proteins; odontoblasts and ameloblasts did not express these genes. Osteonectin was expressed by osteoblasts and hypertrophic chondrocytes as well, whereas in the molars it was produced exclusively by odontoblasts. Osteocalcin was expressed specifically by osteoblasts in the developing metatarsals. In tooth, osteocalcin transcripts were detected in odontoblasts. Finally, amelogenin was a specific product of ameloblasts. Thus, a sequential and cell type-restricted expression of matrix proteins takes place during the development of the mineralized tissues. The expression patterns of the transcripts encoding the bone matrix proteins suggest different biological roles depending on the time and site of expression.

Amelogenin↗
PubMed1997

Evaluation of vertebral volumetric vs. areal bone mineral density during growth.

Bone mineral "density" (BMD) measured by dual-energy X-ray absorptiometry (DEXA) does not represent the volumetric density (grams per cubic centimeter), but rather the areal density (grams per square centimeter). This distinction is important during growth. The purpose of this study was to measure vertebral dimensions in cadavers of young pigtail macaques (Macaca nemestrina), and to derive equations to predict the volumetric bone density from noninvasive measurements. We measured the areal bone density by DEXA, vertebral volume by underwater weighing, mineral content by ashing, dimensions of lumbar vertebrae by calipers, and dimensions of vertebrae by radiography. Somatometric measurements of the female lumbar vertebral bodies showed that the shape changed during growth. The bone mineral content from the densitometer correlated significantly with the ash weight (r = 0.99, error 8.7%). The correlation coefficient between the volumetric bone mineral density and areal BMD measurement was significant (r = 0.68, p < 0.0001) with a 9.5% error; this improved significantly to 0.82 (7.2% error) when the BMD was divided by the vertebral depth from the radiograph. A real BMD showed a strong correlation with age (r = 0.82, p < 0.0001), with an average increase of 7.4%/year. In contrast, volumetric mineral density showed a weak relationship with age (r = 0.43, p < 0.01), for an average increase of 1.5%/year. When studying bone mineral density during growth, the differences between volumetric and areal bone mineral density should be taken into consideration.

Absorptiometry, Photon↗
PubMed2003

Molecular interfacial reactions between Pu(VI) and manganese oxide minerals manganite and hausmannite.

The sorption of Pu(VI) onto manganite (MnOOH) and hausmannite (Mn3O4) was studied as a function of time, solution pH, and initial plutonium concentration. Kinetic experiments indicate that the surface complexation of plutonium occurs over the first 24 h of contact with the mineral surface. The sorption increases with pH beginning at pH 3 until it reaches a maximum value of 100% at pH 8 (0.0011-0.84 micromol of Pu/m2 of manganite and 0.98-1.2 micromol of Pu/m2 of hausmannite) and then decreases over the pH range from 8 to 10. The ratio of solid to solution was 10 mg/mL for manganite experiments and 4 mg/mL for hausmannite samples. Carbonate was not excluded from the experiments. The amount of plutonium removed from the solution by the minerals is determined by a combination of factors including the plutonium solution species, the surface charge of the mineral, and the mineral surface area. X-ray absorption fine structure taken at the Pu L(III) edge were compared to plutonium standard spectra and showed that Pu(VI) was reduced to Pu(IV) after contact with the minerals. Plutonium sorption to the mineral surface is consistent with an inner-sphere configuration, and no evidence of PuO2 precipitation is observed. The reduction and complexation of Pu(VI) by manganese minerals has direct implications on possible migration of Pu(VI) species in the environment.

Adsorption↗
PubMed1994

Changes in bone mineral density associated with dietary-induced loss of body mass in young women.

1. Moderately overweight, premenopausal women were assessed for bone mineral density of the total body, lumbar spine and proximal femur before and after 6 months of modest dietary restriction (minimum 4800 kJ/day). The aim was to evaluate the effect of loss of body mass on bone mineral density. 2. Dietary assessment included two analyses of 3 day weighed food intakes, one before and the other after 4 months of dietary restriction. Energy and calcium intakes were significantly reduced by 27% and 5%, respectively. The change in calcium intake was negatively and significantly related to initial levels of calcium intake. 3. A significant mean loss of 3.4 +/- 3.1 kg in body mass was achieved mainly in the first 3 months of the study; it was accompanied by significant losses at 6 months in bone mineral density in the total body of 0.7% and in the lumbar spine of 0.5%. There were no changes in the femur. 4. The change in bone mineral density in the total body was significantly related to the reduced absolute calcium intake, initial bone mineral density and loss of body mass. The change in bone mineral density in the spine was significantly related to the change in calcium intake. 5. These modest losses could be a threat in women with lower bone mineral density, and indicate the importance of maintaining a high intake of calcium during dietary restriction.

Absorptiometry, Photon↗
PubMed1994

A comparison of bone mineral density between Caucasian, Asian and Afro-Caribbean women.

1. We analysed the lumbar spine (L2-L4) and femoral neck bone mineral density results of Caucasian (n = 2232), Asian (Indian sub-continent) (n = 153) and Afro-Caribbean (n = 102) women referred for bone densitometry over a 30 month period. To assess the risk of osteoporosis, the results of Caucasian and Asian women were compared with those of a reference Caucasian population supplied by Lunar. 2. Subject characteristics were similar in all three groups, other than expected ethnic differences in stature and weight. We found that lumbar spine and femoral neck bone mineral density in Caucasians was lower than in Afro-Caribbeans, but higher than in Asians. Consistent with this, bone mineral density was also lower in Asians as compared with the reference Caucasian population, both at the lumbar spine and femoral neck. As a consequence, a higher proportion of Asian women were classified as being at increased risk of osteoporosis than Caucasian women. 3. Since ethnic differences in skeletal size might influence bone mineral density, we also obtained values for bone mineral content in Caucasian and Asian women that were corrected for projected skeletal area, and weight and years since menopause, using regression equations derived from the Caucasian study population. After this analysis, the difference in bone mineral content between Caucasians and Asians at the lumbar spine disappeared, while that at the femoral neck persisted. 4. We conclude that the assessment of risk of osteoporosis in Asian women by comparing bone mineral density with a reference Caucasian population may have limited validity because of the influence of skeletal size on such measurements.

Absorptiometry, Photon↗
PubMed2003

Bone mineral density outcomes following long-term treatment with subcutaneous testosterone pellet implants in male hypogonadism.

BACKGROUND: Osteoporosis is a common complication of untreated male hypogonadism. Even mild hypogonadism due to suboptimal testosterone replacement may result in decreased bone mineralization and osteoporosis. OBJECTIVE: To assess bone mineral density in hypogonadal men following long-term long-acting subcutaneous testosterone pellet implants as replacement therapy. PATIENTS: A cross-sectional study of 37 patients with primary or secondary hypogonadism receiving long-term (mean 6.6 years) subcutaneous testosterone pellet implants as replacement therapy. MEASUREMENTS: Bone mineral density was measured in all patients using dual energy X-ray absorptiometry. Serum testosterone 3-4 months after insertion of pellets was measured in all patients to assess adequacy of replacement therapy. RESULTS: Mean areal bone mineral density were 1.02 (SD 0.14) g/cm2 with a mean Z score of -0.64 (SD 1.3) and 0.87 (SD 0.13) g/cm2 with a mean Z score of -0.72 (SD 1.2) at lumbar spine and neck of femur, respectively. Mean serum testosterone 3-4 months after pellets insertion was 15.45 nmol/l (SD 4.2 nmol/l). There was no significant correlation between bone mineral density and patient's age at start or duration of testosterone therapy. CONCLUSIONS: Bone mineral density in long-term regularly treated hypogonadal men was not different from the age-matched reference range for normal men. Long-acting subcutaneous testosterone pellet implants as replacement therapy in male hypogonadism are safe, acceptable to the patient, result in adequate bone mass accumulation and maintenance of normal bone mineral density. By provision of sustained physiological levels of testosterone they may contribute to increased androgen effect at the receptor level.

Adult↗
PubMed2003

Dose-dependent effects of strontium on osteoblast function and mineralization.

BACKGROUND: Strontium-ranelate is now being used in the treatment of osteoporosis in elderly patients. As the majority of these patients already have a decreased renal function they are at an increased risk for accumulation of the element. Recent findings from epidemiologic studies in dialysis patients and experimental data obtained in a chronic renal failure (CRF) rat model established a dose-related multiphasic effect of strontium (Sr) on bone formation. To confirm these in vivo findings an in vitro set-up, consisting of primary rat osteoblast cultures, was applied. Sr was added to the culture medium at concentrations of 0, 0.5, 1.0, 2.0, 5.0, 20, and 100 microg/mL, respectively. METHODS: Calcium incorporation (index of mineralization) and alkaline phosphatase activity were determined in the medium during the culture period, while at the end of the experiment, nodule formation (mineralized + unmineralized area) was quantified using a digital imaging system. mRNA synthesis of various osteoblast specific genes was assessed by means of reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Compared to the control group (0 microg/mL Sr), a significantly reduced nodule formation in the presence of an intact mineralization was found for the lowest 0.5 and 1 microg/mL Sr doses, suggesting an impaired in vitro osteoblast differentiation. Both nodule formation and mineralization were normal for the 2 and 5 microg/mL doses. For the highest Sr doses (20 and 100 microg/mL) a reduced mineralization was observed in the presence of an intact nodule formation indicating an inhibitory effect on the hydroxyapatite formation. The alkaline phosphatase activity reflected the multiphasic pattern of the nodule formation while the calcium incorporation corresponded with the pattern of nodular mineralization. No variations in cell proliferation were found. RT-PCR revealed that Sr interfered with the osteoblast at the level of the mRNA synthesis of several relevant genes. CONCLUSION: Using the proposed in vitro model we confirmed the multiphasic effect of Sr on bone formation previously demonstrated in a CRF rat model. The data presented allow us to suggest that at low concentrations Sr interferes with the bone formation at the level of cell differentiation, whereas at high concentrations the disturbed mineralization in the presence of an intact nodule formation is indicative for a physicochemical interference of Sr with the hydroxyapatite formation.

Alkaline Phosphatase↗