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PubMed2001

Assessment of commercial laboratories performing hair mineral analysis.

CONTEXT: Hair mineral analysis is being used by health care practitioners and promoted by laboratories as a clinical assessment tool and to identify toxic exposures, despite a 1985 study that found poor reliability for this test. OBJECTIVE: To assess whether the reliability of data from commercial laboratories advertising multimineral hair analyses for nutritional or toxicity assessment has improved since the 1985 study. DESIGN, SETTING, AND PARTICIPANTS: A split hair sample taken from near the scalp of a single healthy volunteer was submitted for analysis to 6 commercial US laboratories, which analyze 90% of samples submitted for mineral analysis in the United States. MAIN OUTCOME MEASURES: Agreement of test results for each analyte, laboratory reference ranges, laboratory characteristics, and interpretation of health implications. RESULTS: Laboratory differences in highest and lowest reported mineral concentrations for the split sample exceeded 10-fold for 12 minerals, and statistically significant (P<.05) extreme values were reported for 14 of the 31 minerals that were analyzed by 3 or more laboratories. Variations also were found in laboratory sample preparation methods and calibration standards. Laboratory designations of normal reference ranges varied greatly, resulting in conflicting classifications (high, normal, or low) of nearly all analyzed minerals. Laboratories also provided conflicting dietary and nutritional supplement recommendations based on their results. CONCLUSIONS: Hair mineral analysis from these laboratories was unreliable, and we recommend that health care practitioners refrain from using such analyses to assess individual nutritional status or suspected environmental exposures. Problems with the regulation and certification of these laboratories also should be addressed.

Biomarkers↗
PubMed1996

Tracing the pathway between mutation and phenotype in osteogenesis imperfecta: isolation of mineralization-specific genes.

The brittleness of bone in people with lethal (type II) osteogenesis imperfecta, a heritable disorder caused by mutations in the type I collagen genes, arises from the deposition of abnormal collagen in the bone matrix. The inability of the abnormal collagen to participate in mineralization may be caused by its failure to interact with other bone proteins. Here, we have designed a strategy to isolate the genes important for mineralization of collagen during bone formation. Cells isolated from 16-day embryonic chick calvaria and seeded post-confluence in culture deposited a mineralized matrix over a period of 2 weeks. Chick skin fibroblasts seeded and cultured under the same conditions did not mineralize. Using RT-PCR, we prepared short cDNAs (approximately 300 bp) corresponding to the 3' ends of mRNA from fibroblasts and separately from the mineralizing calvarial cells. Subtractive cDNA hybridization generated a pool of cDNAs that were specific to mineralizing calvarial cells but not to fibroblasts. Screening of 100,000 plaques of a chick bone ZAP Express cDNA library with this pool of mineralizing-specific cDNAs identified ten clones which comprised full-length cDNAs for the bone proteins osteopontin (eight of the ten positives), bone sialoprotein II (one of the ten positives), and cystatin (one of the ten positives). cDNAs for type I collagen, fibronectin, alkaline phosphatase, house-keeping genes, and other genes expressed in fibroblasts were not identified in this preliminary screen. The pool of short cDNAs is likely to comprise cDNAs for further bone-specific genes and will be used to screen the entire bone cDNA library of 4.2 million clones.

Alkaline Phosphatase↗
PubMed1990

Expression and ultrastructural immunolocalization of a major 66 kDa phosphoprotein synthesized by chicken osteoblasts during mineralization in vitro.

Embryonic chicken osteoblasts cultured over a 30 day period were used as a model system for studying the expression of bone phosphoproteins during cellular differentiation and the possible role of these proteins in extracellular matrix mineralization. Accumulation of total phosphoprotein in the cultures, as determined by O-phosphoserine (Ser-P) and O-phosphothreonine (Thr-P) amino acid analysis, revealed a greater than 10-fold increase over the 30 day period. Total phosphoprotein synthesis, as assessed by (32P)-, (3H)-Ser-P, and (14C)-Thr-P protein labeling, showed the highest levels concurrent with initial mineral deposition within the matrix. The major phosphoprotein present in chicken bones and synthesized by the cultured osteoblasts had a molecular weight of approximately 66 kDa. This 66 kDa bone phosphoprotein (66 kDa BPP) was purified to homogeneity and was used for antibody production. Application of this antibody in Western blot analysis revealed that 66 kDa BPP was present only in protein extracts of mineralizing cultured osteoblasts and was absent in cultures of non-mineralizing chondrocytes, myoblasts, and tendon fibroblasts. The 66 kDa BPP in vitro accumulated continuously in the extracellular matrix in a manner that paralleled both phosphoprotein synthesis and total phospho-amino acid production. A comparison of the results obtained in vitro to those from developing embryonic tibiae in vivo demonstrated a similar qualitative and temporal expression of phosphoprotein and a continual accumulation of 66 kDa BPP in the matrix with advancing mineralization and developmental age. Ultrastructural immunocytochemistry using the 66 kDa BPP antibody and the protein A-gold technique revealed specific immunolabeling over electron-dense regions of mineralization in the cultures that appeared identical to the distribution of labeling observed in vivo (McKee et al.: Connect. Tissue Res., 21:21-29, 1989; Anat. Rec., 228:77-92, 1990). These results demonstrate that this major 66 kDa BPP was expressed concurrently with other differentiated osteoblast functions and suggests that it may play a role in the initiation or regulation of mineralization.

Animals↗
PubMed1982

[Relation between mineral fertilization and supply of potassium, calcium, magnesium and phosphorus to the population under conditions of intensive plant production in East Germany].

In the past 25 years, mineral fertilization increased considerably in the GDR in the course of the intensification of plant production. This happened on the basis of computer-assisted advice on mineral fertilizing and resulted in the improvement of the mineral contents of the soil and also in a considerable increase in crop yields, the mineral contents typical of the respective plants remaining mostly unchanged or being in part increased. During the same period, the proportion of vegetable foods in the mineral supply to man decreased due to changes in food habits. Nevertheless, most of the P, K and Mg consumed in the nutrition still originates from vegetable products; only in case of Ca, milk is the main course. In the course of this development, the amounts of P, K and Ca consumed in the human nutrition increased, whereas the amount of Mg remained almost unchanged. There is some evidence of the (at last potential) danger of an insufficient supply of Ca and Mg. As the intensive plant production in the GDR furnishes high-mineral crops in sufficient quantity, a better supply of these minerals might be realized by reducing the losses due to processing (extraction rate of cereals, preservation) and by changing the food habits (more vegetable foods, greens).

Agriculture↗
PubMed1991

Initiation of mineralization in bioprosthetic heart valves: studies of alkaline phosphatase activity and its inhibition by AlCl3 or FeCl3 preincubations.

The principal cause of the clinical failure of bioprosthetic heart valves fabricated from glutaraldehyde-pretreated porcine aortic valves is calcification. Other prostheses composed of tissue-derived and polymeric biomaterials also are complicated by deposition of mineral. We have previously demonstrated that: (a) Failure due to calcification of clinical bioprosthetic valves can be simulated by either a large animal circulatory model or subdermal implants in rodents. (b) Calcification of bioprosthetic tissue has complex host, implant, and mechanical determinants. (c) The initial calcification event in the rat subdermal model is the mineral deposition in devitalized cells intrinsic to the bioprosthetic tissue within 48 to 72 h, followed later by collagen mineralization. (d) Initiation of bioprosthetic tissue mineralization, like that of physiological bone formation, has "matrix vesicles" as early nucleation sites. (e) Alkaline phosphatase (AP), an enzyme also associated with matrix vesicles involved in bone mineral nucleation, is present in both fresh and fixed bioprosthetic tissue at sites of initial mineralization. (f) Certain inhibitors of bioprosthetic tissue calcification (e.g., Al3+, Fe3+) are localized to the sites at which alkaline phosphatase is present. On the basis of these results, we hypothesize that alkaline phosphatase is a key element in the pathogenesis of mineralization of bioprosthetic tissue. In the present studies, we focused on the relationship of AP to early events in calcification, and the inhibition of both calcification and AP activity by FeCl3 and AlCl3 preincubations. Subdermal implants of glutaraldehyde pretreated bovine pericardium (GPBP) were done in 3-week-old rats. AP was characterized by enzymatic hydrolysis of paranitrophenyl phosphate (pnpp), and by histochemical studies. Calcification was evaluated chemically (by atomic adsorption spectroscopy) and morphologically (by light microscopy). The results of these studies are as follows: (a) Extractable AP activity is present in fresh but not glutaraldehyde-pretreated bovine pericardial tissue. However, histochemical studies reveal active AP within the intrinsic devitalized cells of GPBP, despite extended glutaraldehyde incubation. (b) Extrinsic AP is rapidly adsorbed following implantation, with peak activity at 72 h (424 +/- 67.2 nm pnpp/mg protein/min enzyme activity [units]), but markedly lesser amounts at 21 days (96.8 +/- 3.9 units). (c) Simultaneously to the AP activity maximum, bulk calcification is initiated, with GPBP calcium levels rising from 1.2 +/- 0.1 (unimplanted) to 2.4 +/- 0.2 micrograms/mg at 72 h, to 55.6 +/- 3.1 micrograms/mg at 21 days, despite a marked decline in AP activity at this later time.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkaline Phosphatase↗
PubMed2006

Mineralization of hydroxyapatite in electrospun nanofibrous poly(L-lactic acid) scaffolds.

A highly porous electrospun poly(L-lactic acid) (PLLA) nanofibrous scaffold was used as a matrix for mineralization of hydroxyapatite. The mineralization process could be initiated by immersing the electrospun scaffold in the simulated body fluids (SBF) at 37 degrees C for varying periods of time. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), wide-angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR), and Raman spectroscopy were used to characterize the composition and the structure of the deposited mineral on the nanofiber surface. Results indicated that the mineral phase was a carbonated apatite with thin flake-like nanostructures. The effects of functional groups on the scaffold surface and anionic additives in the incubation fluids on the nucleation and growth of the mineral were investigated. It was found that a minuscule amount of anionic additives (e.g., citric acid and poly-L-aspartic acid) in the SBF could effectively inhibit the mineral growth. Surface modification of the scaffold was carried out by hydrolysis of PLLA scaffold in NaOH aqueous solution, where carboxylic acid groups were produced without compromising the scaffold integrity. The mineralization process from modified PLLA electrospun scaffolds was significantly enhanced because the calcium ions can bind to the carboxylate groups on the fiber surface.

Anions↗
PubMed1990

Muscle strength as a predictor of bone mineral density in young women.

It is widely accepted that physical activity is beneficial to bone. However, the specific relationships of muscle strength to bone mineral density (BMD) are poorly understood. We examined strength and BMD in 59 women aged 18-31 years who ranged in exercise patterns from sedentary to active. Mineral density of the right proximal femur (hip) and spine (L2-4) was evaluated by dual-energy x-ray absorptiometry. BMD at the midradius was measured by single-photon absorptiometry. Dynamic strength (one repetition maximum) was measured for the following muscle groups: back, elbow flexors (biceps), leg extensors (quadriceps), and the hip flexors, extensors, adductors, and abductors. Isometric grip strength was assessed by dynamometry. Mineral density at the hip correlated independently with muscle strength and body weight, but not with age. Specifically, femoral neck BMD was significantly correlated with back strength and weight, whereas trochanter and overall hip mineral density were significantly related to biceps, back, and hip adductor strength. Hip mineral density was not related to strength of the quadriceps groups or to that of the hip flexors, extensors, or abductors. In addition, muscle strength was an independent predictor of lumbar spine and midradius mineral density. In stepwise multiple regression analysis, biceps strength proved the most robust predictor of hip BMD and grip strength best predicted bone density at the lumbar spine and radius. We conclude that muscle strength is an independent predictor of bone mineral density, accounting for 15-20% of the total variance in bone density of young women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Effects of testosterone and venesection on spinal and peripheral bone mineral in six hypogonadal men with hemochromatosis.

To measure the effect of testosterone replacement and venesection on spinal and peripheral bone mineral we prospectively studied six hypogonadal men and six eugonadal men with idiopathic hemochromatosis for 24 months. Venesections were performed every week on all patients, and intramuscular injections of testosterone were administered every 3 weeks to the hypogonadal men only. Bone mineral was measured by quantitative computed tomography in the spine and by single-photon absorptiometry in the forearm. During the 24 month period of observation serum testosterone concentrations and serum ferritin levels became normal. In the hypogonadal men mean lumbar spine bone mineral increased by 13.1 +/- 4.9% (95% CI, 0.5-25.6) and mean forearm bone mineral increased by 4.7 +/- 3.8% (95% CI, -5.1 to 14.6). In contrast in the eugonadal men treated over the same period, mean lumbar spine bone mineral decreased by 3.5 +/- 2.8% (95% CI, -10.9 to 3.8, P less than 0.01) and mean forearm bone mineral remained virtually unchanged (0.07 +/- 0.9%; 95% CI, -1.7 to 3.1, P less than 0.05). These data suggest that bone mineral increases in the lumbar spine and in the forearm in hypogonadal men with hemochromatosis treated by testosterone replacement and venesection.

Adult↗
PubMed1991

Bone mineral density and mass by total-body dual-photon absorptiometry in normal white and Asian men.

Total body bone mineral density, total body bone mineral mass (TBBM), and bone mineral densities (BMD) in seven different regions of the body were measured in 238 normal men (154 Whites and 84 Asians), age 22-94, using dual-photon absorptiometry. Although Asian men had lower TBBM and BMD in all regions (p less than 0.05) except the arms, when multiple regression was done with body weight, height, and age, no significant differences were found between Asians and Whites for bone measurements. Thus lower bone mineral densities and bone mineral mass in Asian males compared to White males appear to be due to differences in height and weight rather than to ethnic differences. The two groups were combined to derive multiple regression equations for TBBM, total-body BMD, and regional BMD. Age, weight, and height were significant in the multiple regression equations for TBBM, ribs BMD, and legs BMD. Age and weight, but not height, were significant for total-body BMD, trunk BMD, spine BMD, arm BMD, and pelvis BMD. Weight, but neither height nor age, was significant for head BMD. These reference normal bone mineral density and bone mineral mass standards are appropriate for both Asian and White males when adjusted for weight, height, and age.

Absorptiometry, Photon↗
PubMed1992

Bone mineral density in elderly men and women: results from the Framingham osteoporosis study.

Our study investigated bone mineral density of the proximal femur and ultradistal and proximal radius in a population of elderly men and women. The Framingham study started in 1948, following a population-based sample for evaluation of cardiovascular risk factors and events. During the 20th biennial Framingham examination (1988-89) we conducted the Framingham osteoporosis study, measuring bone mineral density in the proximal femur and distal and proximal radius for 1154 study participants. Ages ranged from 68 to 98 years, with a mean age of 76 years. Bone mineral density was measured using Lunar SP2 and DP3 densitometers. This cross-sectional study evaluates mean bone mineral density measurements at each site by 5 year age intervals for men and women, testing for trends in bone density with age. Analyses were repeated adjusting for weight and height. Among the 446 and 708 women, bone mineral density of the femur and bone mineral content of the proximal radius were inversely and significantly related to age in both sexes and were considerably higher in men than women at all sites. The linear decline with age group in our cross-sectional study remained after multivariate adjustment for height and weight. The ultradistal radius showed no significant correlation with age for either sex. There were significant correlations between the bone measurements made at different sites for both men and women (range in r = 0.27-0.89). Cross-sectional curves of bone mineral density with age showed no significant differences in slope between males and females.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

Effects of weight and body mass index on bone mineral density in men and women: the Framingham study.

We evaluated the association of weight and bone mass in elderly male and female subjects of the Framingham osteoporosis study, a subset of the Framingham study cohort. By examining the differences in the correlations of weight with bone mass among men and women in weight-bearing and non-weight-bearing sites and weight change since early adulthood, we attempted to understand different ways in which weight or body mass index affects bone mass. During biennial examination 20 of the Framingham cohort (1988-1989), 693 women and 439 men (mean age 76 years) had proximal femur bone mineral density assessed by dualphoton absorptiometry (DPA) and radius bone mass assessed by single-photon absorptiometry. The majority of these subjects also had spine measurements by DPA. Subjects had been weighed repeatedly over 40 years. After adjusting for other factors affecting bone density, we found that both recent weight and body mass index explained a substantial proportion of the variance in bone mineral density for all sites in women (8.9-19.8% of total variance, all p < 0.01) and for only weight-bearing sites (femur and spine) in men (2.8-6.9% of total variance, all p < 0.01). For bone mineral density at the proximal radius, weight and body mass index accounted for < 1% of variance in men (p NS). Weight change since biennial examination 1 (1948-1951) was the strongest explanatory factor for bone mineral density among women at all sites, but weight change did not affect radius bone mineral density in men. The effect of weight and of weight change on bone mineral density was in general much less in men than in women. Our results suggest that the strong effect of weight on bone mineral density is due to load on weight-bearing bones sexes. The sex difference is unexplained but may be due to adipose tissue production of estrogen in women after menopause.

Absorptiometry, Photon↗
PubMed1994

Role of chondroitin sulfate glycosaminoglycans in mineralizing osteoblast-like cells: effects of hormonal manipulation.

A monoclonal anti-chondroitin sulfate antibody (CS-56) that recognizes native chondroitin sulfate glycosaminoglycans (CSGAG) was used to quantify changes in CSGAG labeling levels in mineralizing human fetal osteoblast-like cell multilayers up to 40 days postconfluence. In control cultures, mean labeling of CSGAG increased in nonmineralized areas from around eight gold probes per micron 2 (gpm) at 20 days to 26 gpm at 40 days. Labeling was markedly increased in the mineralized tissue, to 560 gpm at 30 days and 580 gpm at 40 days. In beta-glycerophosphate-treated cultures, the mineralized areas were increased and appeared earlier (20 days) than in the control cultures. In these cultures, mean CSGASG labeling increased in nonmineralized areas from around 5 gpm at 20 days to 26 gpm at 30 days and was further increased in mineralized areas to 270 gpm at 20 days and 298 gpm at 30 days. Mineralization was not noted in cultures treated with 10(-8) M 1,25-dihydroxyvitamin D, and CSGAG labeling remained low (< 5 gpm) during the study period. These results indicate that an increase in immunoreactive CSGAG is associated with mineralization in this culture system. One possible interpretation of these findings is that proteoglycan molecules or at least their CSGAG side chains may be involved in the mineralization process.

Antibodies, Monoclonal↗
PubMed1996

Dual-energy X-ray absorptiometry studies of bone mineral status in newborn infants.

We studied bone mineral status using dual-energy X-ray absorptiometry (DXA) on 150 singleton newborn infants with birth weights 1002-3990 g and gestational ages (GA) 27-42 weeks. Eighty-five infants were preterm (< 38 weeks), and 79 infants were low birth weight (< or = 2500 g). In addition, we aimed to determined the predictive value of anthropometric measurements, race, and gender on variability in bone mineral status. Data were acquired using a whole body DXA scanner with a pediatric platform. Scan analyses were performed with software version V5.64P. Results showed a highly significant (p < 0.001 for all comparisons) correlation among the continuous independent variables, gestational age, birth weight, study weight, study bare weight, and study length, and between independent and each of the dependent variables, total body bone mineral content (TB BMC), TB area, and TB bone mineral density (TB BMD). The best single determinant of bone mineral status is body weight, accounting for 95% of TB BMC and TB area and for 86% of TB BMD variation. Body length was the only additional significant predictor of TB area. Inclusion of postnatal age (during the first week after birth), race, gender, or season, either individually or in combination, failed to improve bone mineral status explanation. By term (GA 38-42 weeks, birth weight 2700-3990 g), the mean TB BMC was 68.2 g, TB area 307.6 cm2, and TB BMD 0.221 g/cm2. We conclude that DXA can be performed even in small preterm infants during the newborn period. Our results can be used as a basis for further studies in physiologic and pathologic situations that might affect bone mineralization in infants.

Absorptiometry, Photon↗
PubMed2006

Constitutive expression of thrombospondin 1 in MC3T3-E1 osteoblastic cells inhibits mineralization.

Thrombospondin 1 (TSP1) is a multifunctional extracellular glycoprotein present mainly in the fetal and adult skeleton. Although an inhibitory effect of TSP1 against pathological mineralization in cultured vascular pericytes has been shown, its involvement in physiological mineralization by osteoblasts is still unknown. To determine the role of TSP1 in biomineralization, mouse osteoblastic MC3T3-E1 cells were cultured in the presence of antisense phosphorothioate oligodeoxynucleotides complementary to the TSP1 sequence. The 18- and 24-mer antisense oligonucleotides caused concentration-dependent increases in the number of mineralized nodules, acid-soluble calcium deposition in the cell/matrix layer, and alkaline phosphatase activity within 9 days, without affecting cell proliferation. The corresponding sense or scrambled oligonucleotides did not affect these parameters. In the antisense oligonucleotide-treated MC3T3-E1 cells, thickened extracellular matrix, well-developed cell processes, increased intracellular organelles, and collagen fibril bundles were observed. On the other hand, the addition of TSP1 to the culture decreased the production of a mineralized matrix by MC3T3-E1 cells. Furthermore, MC3T3-E1 clones overexpressing mouse TSP1 were established and assayed for TSP1 protein and their capacity to mineralize. TSP1 dose-dependently inhibited mineralization by these cells both in vitro and in vivo. These results indicate that TSP1 functions as an inhibitory regulator of bone mineralization and matrix production by osteoblasts to sustain bone homeostasis.

Alkaline Phosphatase↗
PubMed1994

Mathematical model for the mineralization of bone.

A mathematical model is presented for the transport and precipitation of mineral in refilling osteons. One goal of this model was to explain calcification "halos," in which the bone near the haversian canal is more highly mineralized than the more peripheral lamellae, which have been mineralizing longer. It was assumed that the precipitation rate of mineral is proportional to the difference between the local concentration of calcium ions and an equilibrium concentration and that the transport of ions is by either diffusion or some other concentration gradient-dependent process. Transport of ions was assumed to be slowed by the accumulation of mineral in the matrix along the transport path. The model also mimics bone apposition, slowing of apposition during refilling, and mineralization lag time. It was found that simple diffusion cannot account for the transport of calcium ions into mineralizing bone, because the diffusion coefficient is two orders of magnitude too low. If a more rapid concentration gradient-driven means of transport exists, the model demonstrates that osteonal geometry and variable rate of refilling work together to produce calcification halos, as well as the primary and secondary calcification effect reported in the literature.

Animals↗
PubMed2000

BET Measurements: Outgassing of Minerals.

Outgassing minerals at elevated temperatures prior to BET measurements can lead to phase changes, especially in the case of amorphous and poorly crystalline materials. In order to evaluate the applicability of the BET method when low outgassing temperatures are required, selected aquifer minerals were outgassed at different temperatures and for different times. The studied minerals are 2-line ferrihydrite, goethite, lepidocrocite, quartz, calcite, alpha-alumina, and kaolinite. The results demonstrate that measured specific surface areas of iron oxides are strongly dependent on outgassing conditions because the surface area increased by 170% with increasing temperature. In the poorly crystalline minerals, phase changes caused by heating were observed at temperatures lower than 100 degrees C. Therefore low outgassing temperatures are preferable for minimizing phase changes. As demonstrated in this study, stable BET values can be obtained by increasing the outgassing time without heating iron oxides. For quartz, calcite, alpha-alumina, and kaolinite, stable BET values were obtained after outgassing the minerals at 100 to 250 degrees C for 2 h. However, outgassing these minerals at room temperature (20 degrees C) only resulted in minor errors, implying that aquifer sediments containing poorly crystalline materials can be outgassed at low temperatures if the outgassing time is increased. Scanning electron microscopy of the studied minerals demonstrated that the particle size as calculated from BET data compares well with particle size observed by scanning electron microscopy images. Copyright 2000 Academic Press.

Journal Article↗
PubMed1994

A unique protonated phosphate group in bone mineral not present in synthetic calcium phosphates. Identification by phosphorus-31 solid state NMR spectroscopy.

The detailed chemical composition and microstructure of freshly deposited bone mineral, and how these properties change with maturation of the mineral, have been studied intensively and still remain controversial. For example, current analytical technology is inadequate for the unambiguous characterization of the monohydrogen phosphate ions in bone mineral. Using a differential cross polarization/magic angle spinning solid state nuclear magnetic resonance spectroscopy technique, we suppress the dominant orthophosphate (PO4-3) signal to reveal the spectra of the minor phosphate constituents. This method depends upon differences in the cross polarization time constants for phosphorus-31 nuclei in protonated and non-protonated phosphate ions. It is now possible for the first time to directly measure both the proportion of acid phosphate (HPO4-2) as well as the parameters which characterize its isotropic and anisotropic chemical shift. In bone from three species at several developmental stages, we have found a single type of acid phosphate species, identical in all of the specimens examined. The phosphorus-31 isotropic chemical shift of this acid phosphate group in bone mineral corresponds precisely with that of acid phosphate in octacalcium phosphate, and not with that of brushite. In contrast, the bone acid phosphate anisotropic chemical shift parameters are close to those of brushite, and differ significantly from those of octacalcium phosphate. The orthophosphate resonances of bone mineral, synthetic hydroxyapatite and synthetic octacalcium phosphate share identical chemical isotropic shifts, and similar chemical shift anisotropies. The implication of these results is that the intimate structure of the acid phosphate group in bone mineral is unique, and that none of the common synthetic calcium phosphates accounts well for all of the observed solid state phosphorus-31 NMR properties of bone mineral.

Animals↗
PubMed1996

Ultrastructural analysis of mineralized matrix from human osteoblastic cells: effect of tumor necrosis factor-alpha.

Recent work by a number of investigators has demonstrated that the process of bone matrix formation and mineralization is under the influence of growth factors and cytokines present in the local environment. Utilizing primary and established osteoblast cell culture systems, these studies have examined the regulation of bone matrix protein synthesis and deposition into the extracellular matrix (ECM) and subsequent mineralization. In previous studies, we have utilized the human osteoblastic cell line, HOS TE85, to study the effects of Tumor Necrosis Factor-alpha (TNF-alpha) on the regulation of matrix proteins and proteolytic function in monolayer cultures as well as during the development and calcification of ECM formed by HOS TE85 cells during extended culture. Our studies demonstrate that TNF-alpha inhibited formation and mineralization of nodules. In the study reported here, we evaluated the ultrastructural morphology of the cell-matrix complex formed by HOS TE85 cells in the presence and absence of TNF-alpha at selected time points during the matrix development process utilizing both transmission electron microscopy and light microscopy. In the presence of TNF-alpha, the cell-matrix complex does not develop normally, with a lack of organization and mineralization, when compared to untreated cells. The lack of mineralization appears to result from the lack of normal collagen fibril deposition and formation of an appropriate ECM essential for the mineralization process. These results support our previous observations that TNF-alpha inhibits HOS TE85 cells from forming a mineralizing ECM by inhibiting incorporation of collagen into the ECM and inducing the synthesis of proteolytic enzymes capable of degrading collagen in the ECM.

Calcification, Physiologic↗