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PubMed1989

Estimation of the bone mineral density variation associated with changes in turnover rate.

Bone matrix mineral density (BMDn, fraction of maximum) is the mean mineral density of a bone sample comprising moieties of bone of varying ages/mineral densities. A method for calculating BMDn as a function of bone turnover rate is presented. The method is based on a mineralization curve defined by values for mineralization lag time, total mineralization time, and levels of primary and final mineralization. The calculations illustrate that BMDn decreases linearly in direct proportion to increases in bone turnover rate, and that the slope of the line is dependent on the assumptions used to calculate the mineralization curve. BMDn variation is important because it is reflected in whole bone density variation, independent of changes in bone mass, when bone turnover rate is altered.

Aging↗
PubMedDate not supplied

What can in vitro methods tell us about mineral availability?

In vitro studies of mineral bioavailability are useful because they are faster and less expensive than in vivo studies and because they offer better control over experimental variables. Selection of conditions for in vitro assays of mineral availability is arbitrary. Conditions vary widely among laboratories and with the mineral of interest. Absorption takes place in vivo under conditions that allow ongoing influx and efflux of nutrients and digestive secretions. Conditions in the digestive tract respond to the bulk and nutrient composition of a meal. How does one reproduce these conditions in a closed in vitro system? Correlations between in vivo and in vitro assays may depend on choice of conditions for in vivo studies. Studies of mineral bioavailability from soils have developed to the point that mathematical models have been developed that predict the bioavailability of various minerals to plants under field conditions. Definition of such a model for mineral bioavailability to animals or humans will probably be more difficult to achieve. More information is needed on the nature of nonmineral components of foods and how they interact with minerals.

Absorption↗
PubMedDate not supplied

Bone mineralization and calciotropic hormones in children with hyperthyroidism. Effects of methimazole therapy.

We studied bone mineralization and calcium homeostasis in two children with hyperthyroidism before and during 3 yr of methimazole therapy in order to evaluate the effects of thyrotoxicosis and its therapy on mineral metabolism. Case 1, female, 4.1 year old with hyperthyroidism from 6 months. Biochemical data: increased thyroid function, phosphate and osteocalcin, decreased 1,25(OH)2D levels. X-ray: severe osteoporosis; bone mineral content (BMC) -23.0%, BMC/BW -25.1%. Case 2, female, 7.4 year old with hyperthyroidism from 9 months. Biochemical data: thyroid function, ionized calcium and osteocalcin were increased, 1,25(OH)2D and intact PTH were decreased. X-ray: severe osteoporosis: BMC -32.8%, BMC/BW -36.0. After the patients were euthyroid, they showed an increase of 1,25(OH)2D and intact PTH into normal values and a fall in calcium and phosphate. Osteocalcin levels returned in normal range one yr after first evaluation. Bone mineral analysis showed no variation of BMC and BMC/BW in the first 6 months of therapy and an increase in the following 6 months. In the following two years BMC and BMC/BW rose to normal range. Our study provides further evidence that in hyperthyroidism an altered mineral homeostasis is present with a reversible disturbance in vitamin D metabolism. We found that the return to euthyroidism was associated with a normalization of mineral homeostasis and with a recovery of bone mineralization. Osteocalcin assay may be an useful index to monitor bone metabolism in hyperthyroidism.

Absorptiometry, Photon↗
PubMed2003

Osteopontin facilitates bone resorption, decreasing bone mineral crystallinity and content during calcium deficiency.

Osteopontin null-mice were previously shown to have bones containing more mineral and larger mineral crystals. These bones were independently seen to be resistant to ovariectomy-induced remodeling. To separate the physicochemical effects of osteopontin, which is an in vitro inhibitor of mineral crystal formation and growth, from effects of osteopontin on in vivo bone remodeling, this study examined mature (5-month-old) osteopontin-null (Opn-/-) and wildtype (WT) mice given a calcium-deficient diet. Biochemical parameters were measured during 4 weeks of Ca deficiency, followed by 1 week of refeeding adequate Ca. Ca deficiency caused a transiently greater rise in bone resorption in WT than Opn-/- mice (P = 0.01), whereas only the Opn-/- mice tended to increase Ca absorption (P = 0.08), yet both groups showed elevated levels of parathyroid hormone (PTH) (P < 0.001). The rise in markers of bone formation due to Ca deficiency was similar in both groups during Ca deficiency. Fourier transform infrared microspectroscopy assessed mineral properties at 20 microm spatial resolution in different anatomic regions of the bone. The Ca-deficient Opn-/- animals had slightly increased mineral content as compared to the WT, and there was a significant increase in the mineral content of older (endosteal) bone, implying that osteoclast recruitment was impaired. Crystallinity in the Ca-deficient Opn-/- bones was increased relative to the Ca-deficient WT at all sites except adjacent to the periosteum (younger mineral). These data suggest that osteopontin has both a physicochemical effect (inhibiting crystal growth and crystal proliferation) and a role in osteoclast recruitment, and in its absence, extraskeletal organs maintain calcium homeostasis.

Amino Acids↗
PubMed2001

Toluene mineralization and growth potential of Pseudomonas putida PaW164 under toluene-limiting conditions.

Toluene-induced cells of Pseudomonas putida PaW164 (pWWO-164) were monitored for growth potential, maintaining the TOL plasmid, and potential toluene mineralization activity in toluene-amended and nonamended soil. A follow-up study was done in a carbon-free mineral salts solution to obtain further information on physiological changes that occur during starvation. These studies showed that there was a larger decline in colony forming units (CFUs) recovered on a toluate- or benzoate-defined mineral salts medium than on a complex agar medium, a greater percent decrease of CFU than of potential mineralization activity, no decrease in direct counts, and no loss of the TOL plasmid during starvation. Toluene-induced cells also showed an increasing lag time and a decreasing potential for mineralization of (14)C-toluene with starvation. In contrast, the lag time for mineralization of glucose was longest at the onset of starvation and reached a minimum by 3 days; thereafter, the potential for glucose mineralization remained high.

Cell Division↗
PubMed2004

Combining in situ reverse transcriptase polymerase chain reaction, optical microscopy, and X-ray photoelectron spectroscopy to investigate mineral surface-associated microbial activities.

A study was undertaken to investigate expression of a gene encoding a c-type cytochrome in cells of the dissimilatory metal reducing bacterium (DMRB) Geobacter sulfurreducens during association with poorly crystalline and crystalline solid-phase Fe(III)-oxides. The gene encoding OmcC (outer membrane c-type cytochrome) was used as a target for PCR-based molecular detection and visualization of omcC gene expression by individual cells and aggregates of cells of G. sulfurreducens associated with ferrihydrite and hematite mineral particles. Expression of omcC was demonstrated in individual bacterial cells associated with these Fe-oxide surfaces by in situ RT-PCR (IS-RT PCR) and epifluorescence microscopy. Epifluorescence microscopy also permitted visualization of total DAPI-stained cells in the same field of view to assess the fraction of the cell population expressing omcC. By combining reflected differential interference contrast (DIC) microscopy and epifluorescence microscopy, it was possible to determine the spatial relationship between cells expressing omcC and the mineral surface. Introduction of the fluorescently labeled lectin concanavalin A revealed extracellular polymeric substances (EPS) extending between aggregations of bacterial cells and the mineral surface. The results indicate that EPS mediates an association between cells of G. sulfurreducens and ferrihydrite particles, but that direct cell contact with the mineral surface is not required for expression of omcC. XPS analysis revealed forms of reduced Fe associated with areas of the mineral surface where EPS-mediated bacterial associations occurred. The results demonstrate that by combining molecular biology, reflectance microscopy, and XPS, chemical transformations at a mineral surface can be related to the expression of specific genes by individual bacterial cells and cell aggregates associated with the mineral surface. The approach should be useful in establishing involvement of specific gene products in a wide variety of surface chemical processes.

Bacterial Proteins↗
PubMed2005

Biomimetic mineralization of partially bioresorbable glass fiber reinforced composite.

The aim of this study was to investigate the biomimetic mineralization on the surface of a glass fiber reinforced composite with partially resorbable biopolymer matrix. The E-glass fibers were preimpregnated with a novel biopolymer of poly(hydroxyproline) amide, and further impregnated in the monomer system of bis-phenyl glycidyl dimethacrylate (Bis-GMA)--triethylene glycol dimethacrylate (TEGDMA), which formed interpenetrating polymer networks (IPN) with the preimpregnation polymer. After light-initiated polymerization of the monomer system, the rhombic test specimens (n = 6) were immersed in the simulated body fluid (SBF) with the bioactive glass for 24 h, and then the apatite nuclei were allowed to grow for 1, 3, 5 and 7 days in the SBF. The control test specimens (n = 3) were immersed in SBF without the bioactive glass. According to the scanning electron microscope (SEM), a mineral layer was formed on the surface of all the specimens, which were immersed with bioactive glass. The layer was thickened by the prolonged immersion time to a uniform layer. The Ca/P atomic ratio of the mineral varied between 1.30 and 1.54 as analyzed by the energy dispersive X-ray analysis (EDXA). The Fourier transform infrared spectroscopy (FT-IR) spectra gave signals for the mineral, which are characteristic of both bone-like apatite and orthocalciumphosphate. In conclusion, the mineral layer was formed on the surfaces of the specimens by biomimetic mineralization, the mineral being a mixture of bone-like apatite, orthocalciumphosphate and other calcium phosphates.

Apatites↗
PubMed1985

Prediction of postmenopausal fracture risk with use of bone mineral measurements.

In a study of 1098 women (mean age, 63.3 years) nonspine fracture incidence and prevalence rates and spine fracture prevalence rates were compared by quintile of bone mineral content at the proximal radius, distal radius, os calcis, and lumbar spine. The risk of fracture associated with varying bone mineral content levels was explored with use of estimated odds ratios. Risk of fracture is significantly increased with diminishing quintiles of bone mineral content. Subjects in the lowest quintile of os calcis bone mineral content have a nonspine fracture risk 10 times greater than subjects in the highest bone mineral content quintile. The os calcis bone mineral content measurement is the best predictor of nonspine fracture risk and is also the best overall indicator of spine fracture risk. Therefore measurement of os calcis bone mineral content may be useful for routine risk evaluation of perimenopausal women. The ability to predict individual risk should allow for more rational preventive regimens.

Adult↗
PubMed1992

Salt intake of rats fed diets deficient in calcium, iron, magnesium, phosphorus, potassium, or all minerals.

Groups of nine to ten male rats fed diets deficient in calcium, iron, magnesium, phosphorus, potassium, or all minerals (i.e. no mineral mix) were given 0.3 M NaCl and water to drink. Over the first 30 days of dietary treatment, 0.3 M NaCl intake was progressively increased by deprivation of calcium or iron, unaltered by deprivation of phosphorus, and increased and then decreased by deprivation of magnesium, potassium, or all minerals. The changes in NaCl intake of rats deprived of potassium or all minerals were matched by corresponding changes in water intake. Water intakes of the other groups were unaltered. Thus, NaCl preference was increased by deprivation of calcium or iron, unaltered by deprivation of phosphorus, potassium, or all minerals, and decreased by deprivation of magnesium. To determine whether these changes were specific to the salty modality, animals maintained for 32 days on the diets deficient in calcium, iron, magnesium, and phosphorus received 24-h two-bottle tests with water vs. 2.5 mM saccharin, 2.5 mM citric acid, 0.368 mM sucrose octa-acetate, or 0.3 M NaCl. Relative to controls, rats deprived of calcium drank less 2.5 mM saccharin, those deprived of magnesium drank less 0.3 M NaCl, and those deprived of calcium or iron drank more 0.3 mM NaCl. These results show that different mineral deficiencies have different effects on NaCl intake. They argue against the hypothesis that animals deprived of any mineral develop a chronic appetite for salt.

Animals↗
PubMed1985

The effect of lactation on the mineral distribution profile of the rat femur by single photon absorptiometry.

The distribution of bone mineral in excised femurs from lactating and nonlactating control rats was localized and quantitated using single photon absorptiometry. Bone mineral content was measured proximodistally in nine sequential 0.32 cm increments along the femur length and then plotted as a function of the distance from the proximal end of the femur. The plots described a mineral distribution profile and revealed that bone loss following lactation was site specific, being greater in the metaphyseal regions (23-36%) than in the diaphyseal area (14-20%). The change in total bone mineral of femur caused by lactation was estimated by integrating the mineral distribution profile plots. The 28% lower bone mineral determined by this method was in close agreement with the 27% difference determined from femur dry weight measurements. Reproducibility of measurements with 10 repositionings of a single femur was within 4% at all but the 2 most distal sites. Variation in the estimated total bone mineral was 1.3%.

Animals↗
PubMed2004

Alterations in mineral composition observed in osteoarthritic joints of cynomolgus monkeys.

Osteoarthritis (OA) is a prevalent joint disease that affects more than 40 million Americans and is characterized by degeneration of the articular cartilage and thickening of the underlying subchondral bone. Although subchondral bone thickening has been implicated in articular cartilage degeneration, very little is known about the composition of subchondral bone in OA. In the present study, infrared microspectroscopy (IRMS) was used to determine the chemical composition of the calcified cartilage-subchondral bone plate in a monkey model of OA. Specifically, the levels of mineralization (mineral/protein ratio), carbonate accumulation (carbonate/protein ratio), crystallinity, and collagen structure were determined as a function of animal age and OA severity. OA severity was assessed using a grading scheme that included scores or measurements for several histomorphometric parameters including articular cartilage fibrillation or clefting, subchondral bone thickness, and numbers of tidemarks and chondrocyte clones. Individual scores and measurements were summarized using principal components (factor) analysis. Results demonstrated that the level of mineralization and carbonate content increased as a function of animal age. In addition, bone mineralization level increased as subchondral bone thickness increased. Dramatic increases in the mineralization level and carbonate accumulation were also observed as a function of the number of tidemarks. The presence of multiple tidemarks indicates the occurrence of one or more additional phases of cartilage calcification, suggesting that the observed compositional changes are due to cartilage mineralization. Our results support a reactivation of endochondral ossification that occurs with age, which is more pronounced in OA. No relationships were observed between mineral crystallinity and collagen cross-linking as a function of age or OA severity. In summary, compositional analysis of the mineralized plate beneath the articular cartilage in OA is characterized by thickened, overmineralized calcified cartilage or subchondral bone, which likely puts added mechanical stress on the joint, contributing to the progression of OA.

Animals↗
PubMed2006

Gastric preloads of corn oil and mineral oil produce different patterns of increases of c-Fos-like immunoreacitve cells in the brain of 9-12 day-old rats.

Equivolumetric gastric preloads of corn oil and mineral oil administered to rats on postnatal day 12 (P12) inhibited intake equally during a 30-min test of independent ingestion (II), but preloads of corn oil inhibited intake significantly more than preloads of mineral oil on P15 and P18 [Weller, A., Gispan, I.H., Armony-Sivan, R., Ritter, R.C., Smith, G.P., 1997. Preloads of corn oil inhibit independent ingestion on postnatal day 15 in rats. Physiol. Behav. 62, 871-874]. It is possible that the equivalent inhibition of intake by the oil preloads on P12 resulted from the failure of the preabsorptive sensory properties of the preloads to be discriminated by peripheral or central sensory mechanisms. To investigate this possibility, we administered equivolumetric gastric preloads of 25% corn oil and 25% mineral oil to pups on P9-12 and counted the number of c-Fos-like immunoreactive (CFLI) cells in central sites that are activated by food intake and postingestive preabsortive mechanisms in adult rats and in pups on P10-11. The major result was that preloads of 25% corn oil and 25% mineral oil that produced equivalent inhibition of II intake produced differential increases of CFLI cells in the forebrain and hindbrain. Specifically, preloads of corn oil increased the number of CFLI cells in the caudal Nucleus Tractus Solitarius significantly more than preloads of mineral oil. Furthermore, preloads of corn oil increased the number of CFLI cells in the Paraventricular and Supraoptic nuclei, but preloads of mineral oil did not. This differential pattern of increases of CFLI cells is evidence that the brain discriminates the preabsorptive sensory properties of preloads of corn oil and mineral oil on P9-12.

Aging↗
PubMed2004

Raman microscopy of selected tungstate minerals.

A series of tungstate bearing minerals including scheelite, stolzite, ferberite, hübnerite, wolframite, russellite, tungstenian wulfenite and cuprotungstite have been analyzed by Raman microscopy. The results of the Raman spectroscopic analysis are compared with published data. These minerals are closely related and often have related paragenesis. Raman microscopy enables the selection of individual crystals of these minerals for spectroscopic analysis even though several of the minerals can be found in the same matrix because of the pargenetic relationships between the minerals. The Raman spectra are assigned according to factor group analysis and related to the structure of the minerals. These minerals have characteristically different Raman spectra. The nu1(Ag) band is observed at 909 cm(-1) and although the corresponding nu1(Bu) vibration should be inactive a minor band is observed around 894 cm(-1). The bands at 790 and 881 cm(-1) are associated with the antisymmetric and symmetric Ag modes of terminal WO2. The band at 695 cm(-1) is interpreted as an antisymmetric bridging mode associated with the tungstate chain. The nu4(Eg) band was absent for scheelite. The bands at 353 and 401 cm(-1) are assigned as either deformation modes or as r(Bg) and delta(Ag) modes of terminal WO2. The band at 462 cm(-1) has an equivalent band in the infrared at 455 cm(-1) assigned as delta(as)(Au) of the (W2O4)n chain. The band at 508 cm(-1) is assigned as nu(sym)(Bg) of the (W2O4)n chain.

Electron Probe Microanalysis↗
PubMed2004

Raman spectroscopy of some basic chloride containing minerals of lead and copper.

Raman spectroscopy has been used to characterise several lead and mixed cationic-lead minerals including mendipite, perite, laurionite, diaboléite, boléite, pseudoboléite, chloroxiphite, and cumengéite. Raman spectroscopy enables their vibrational spectra to be compared. The low wavenumber region is characterised by the bands assigned to cation-chloride stretching and bending modes. Phosgenite is a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Each mineral shows different hydroxyl stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl deformation modes. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems involving secondary mineral formation.

Chlorides↗
PubMed2005

Biofortifying crops with essential mineral elements.

Humans require more than 22 mineral elements, which can all be supplied by an appropriate diet. However, the diets of populations subsisting on cereals, or inhabiting regions where soil mineral imbalances occur, often lack Fe, Zn, Ca, Mg, Cu, I or Se. Traditional strategies to deliver these minerals to susceptible populations have relied on supplementation or food fortification programs. Unfortunately, these interventions have not always been successful. An alternative solution is to increase mineral concentrations in edible crops. This is termed 'biofortification'. It can be achieved by mineral fertilization or plant breeding. There is considerable genetic variation in crop species that can be harnessed for sustainable biofortification strategies. Varieties with increased mineral concentrations in their edible portions are already available, and new genotypes with higher mineral densities are being developed.

Crops, Agricultural↗
PubMed2006

Where will large amounts of materials accumulated within the economy go?--A material flow analysis of construction minerals for Japan.

For all countries analyzed so far, Material Flow Analysis/Accounting (MFA) studies indicate that the overall stock of materials within the economy is growing. Most are construction minerals such as asphalt, cement, sand and gravel, crushed stone, and other aggregates. In the analyses described in this paper, flows and stocks of construction minerals were estimated for Japan from the past to the future to elucidate: (1) the mechanisms by which construction minerals become waste, and (2) the future supply of and demand for recycled crushed stone. The following conclusions were drawn: (1) The amounts of waste construction minerals generated have been and will be at much lower levels than the domestic demand for construction minerals. These differences might indicate consistent growth of the stock of construction minerals, which will become waste in the future. However, certain amounts of materials that we account for as stock can be interpreted already in the environment as dead stock or dissipated waste; such materials can be called "missing stock" or "dissipated stock". Capturing that missing or dissipated stock is very important because it provides information that clarifies the environmental impacts and loss of resources that these materials cause; it allows estimation of appropriate future waste generation. (2) The amount of construction minerals that are recognized as waste was estimated to increase in the future. An imbalance in the supply of and demand for recycled crushed stone will likely occur in the near future if an expected decline in future road construction is considered.

Conservation of Natural Resources↗
PubMed1990

Mineral and vitamin D adequacy in infants fed human milk or formula between 6 and 12 months of age.

During the latter half of an infant's first year, adequate mineral and vitamin D intakes may be important not only for the prevention of rickets but also for the attainment of optimal adult peak bone mass. Ingestion of 400 IU vitamin D per day, either as a supplement or contained in formula or table milk, will result in normal serum concentrations of vitamin D,25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D. Human milk from a vitamin D-sufficient mother provides a marginal amount, less than 100 IU/L/day of total vitamin D activity from the vitamin D and 25-hydroxyvitamin D. Infants exclusively fed human milk of vitamin D-deficient mothers, who do not receive additional vitamin D or adequate exposure to sunlight, are at significant risk for vitamin D-deficiency rickets. The low concentration of phosphorus in human milk is adequate for most term infants but probably compounds any vitamin D deficiency. Intake of phosphorus from formula or table milk is more than adequate, and the addition of baby foods increases this mineral's intake to generous levels. Calcium is well absorbed and adequate in human milk if vitamin D is sufficient, but concern exists about calcium intake from infant formulas for this older group. My colleagues and I have conducted studies of bone mineral content and mineral homeostasis in term infants fed human milk (300 mg/L calcium), standard cow milk formula (440/mg/L calcium), or a soybean formula (600 mg/L calcium); our findings suggest that all three types of feedings provided comparable bone mineralization and normal indicators of mineral homeostasis. Mean calcium retentions at 6 months, 9 months, and 12 months in all three groups were between 138 and 205 mg/day, substantially more than the 130 mg/day estimated to be needed from body composition data. Estimates for phosphorus were similarly generous. The questions of whether higher calcium intakes will result in further increases in bone mineral content and of the effect of beikost on calcium absorption from different milks require further study.

Animals↗
PubMed1988

Bone mineralization in former very low birth weight infants fed either human milk or commercial formula.

The bone mineral status of former very low birth weight infants previously fed fortified human milk was evaluated during the posthospitalization period. Anthropometric measurements, bone mineral content, bone width, serum calcium, phosphorus, and albumin concentrations, and alkaline phosphatase activity were evaluated at 10, 16, and 25 postnatal weeks. Infants were fed either commercial formula or unfortified human milk after their hospital discharge. At 16 and 25 weeks postnatally, human milk-fed infants (group HM) had lower bone mineral content (P less than 0.01), bone mineral content/bone width ratio (p less than 0.01), serum phosphorus concentration (p less than 0.03), and higher alkaline phosphatase activity (p less than 0.01) than commercial formula-fed infants (group CM). Growth was similar in both groups. Bone mineral content was correlated positively to serum phosphorus (r = 0.52, p less than 0.05) and inversely to alkaline phosphatase activity (r = -0.63, p less than 0.01) at 25 weeks postnatally. The use of serum biochemical markers, however, could account for only 44% of the variability in bone mineral content. The exclusive feeding of human milk to very low birth weight infants after hospital discharge may place them at risk for mineral deficiencies.

Alkaline Phosphatase↗