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 523 records · Page 29Linked to original sources

Overexpression of IGF-binding protein 5 alters mineral and matrix properties in mouse femora: an infrared imaging study.

The anabolic effects of insulin-like growth factors (IGFs) are modulated by a family of IGF-binding proteins (IGFBPs). Among the six known IGFBPs, IGFBP-5 is considered to play a role in bone formation. To investigate the effects of IGFBP-5 on bone mineral and matrix properties, femurs from transgenic mice overexpressing IGFBP-5 under the control of the osteocalcin promoter were evaluated by Fourier Transform Infrared Imaging (FTIRI). Analyses were done at the time of maximal osteocalcin expression (5 weeks). The spectroscopic parameters monitored were mineral-to-matrix ratio (indicative of the relative amount of mineral present), mineral crystallinity (index of the mineral crystal size and perfection) and collagen maturity (reflecting the ratio of non-reducible and reducible collagen cross-links). Multiple fields were selected for each femur, ranging from epiphysis to diaphysis. Previously, we showed that these transgenic mice display decreased osteoblastic function and osteopenia. In the present work, FTIRI showed that transgenic mice as compared to wild types have a different pattern of bone mineralization and matrix maturation. Specifically, cortical bone, primary spongiosa, and secondary ossification centers had lower values for mineral-to-matrix ratio and collagen maturity. Differences were not statistically significant in all cases although the trends were consistent. The mineral crystallinity did not vary significantly between the two groups, implying that the crystal maturation of mineral was not affected by IGFBP-5 overexpression. This study demonstrates that femurs from transgenic mice over expressing IGFBP-5 under the control of the osteocalcin promoter have modest alterations in mineral and matrix distribution, consistent with a role of IGF in osteoblast maturation.

Animals↗

Small bowel absorption of magnesium and calcium sulphate from a natural mineral water in subjects with ileostomy.

BACKGROUND: In many developed countries, magnesium and calcium intakes do not reach recommendations for a large part of the population. Mineral water may be a useful alternative source of dietary minerals, especially in groups of people at risk for developing deficiency due to low intakes. AIM: To assess if the addition of a natural and mineral-rich water increased small bowel mineral absorption in people with ileostomy. METHODS: A controlled randomised crossover study with two periods of two days each and a minimum 5 days of washout was performed in six ileostomy subjects. Apparent mineral absorption from 0.5 L of natural mineral water with either a high or a low mineral content consumed in the fasting state was compared. The daily addition of minerals corresponded to 2.3mmol magnesium, 6.9 mmol calcium and 7.7mmol sulphate. Ileostomy effluents were sampled and analysed for magnesium, calcium and total sulphate. RESULTS: When compared with the control, the median absorbed amount of magnesium increased from 0.8 (0-1.34) mmol/d to 1.2 (0.8-1.9) mmol/d,which corresponded to a 30% increase (P = 0.028). Median amount of calcium absorbed increased from 8.3 (6.7-13.6) mmol/d to 14.8 (8.3-20.4) mmol/d, i. e. a 45% increase (P = 0.027). The sulphate absorption increased from 1.9 (1.3-2.2) mmol/d to 5.1 (4.2-6.8) mmol/d,which corresponded to 197 % increase (P = 0.028). CONCLUSIONS: The mineral-rich water increased absorption of both magnesium and calcium and can therefore be used as an additional source of minerals. However, consumption with meals may be preferred.

Adult↗

Mineral profile and variability in vegetable amaranth (Amaranthus tricolor).

Populations in North India depend on a number of vegetable crops of which Amaranthus spp. is the most important since it is the only crop available in the hot summer months when no other foliage crop grows in the field. However, reports on mineral composition of leaves are rare with absolutely no information on the qualitative improvement of foliage yield with special reference to minerals. Studies on correlation among the minerals as well as with yield and leaf attributes are also lacking. Hence, we report the proximate mineral composition in 30 strains of A. tricolor along with some suggestions for qualitative improvement of the foliage yield with reference to minerals. Our study showed that vegetable amaranth is a rich source of minerals like calcium (1.7 +/- 0.04 g/100 g), iron (1233.8 +/- 50.02 mg/kg), and zinc (791.7 +/- 28.98 mg/kg). The heritability estimates were high for most of the traits, with potassium and calcium showing high values, while comparatively lower values were recorded for magnesium and nickel. Nickel was the only mineral that showed positive correlation with all the minerals, as well as with leaf size and foliage yield. Zinc showed strong positive relationship with iron (0.66**) and manganese (0.74**), and was the only mineral exhibiting significant positive association with foliage yield. This study would be of use in enhancement of selected minerals in different regions according to local preferences and nutrient deficiency prevalent among the populations.

Amaranthus↗

Relationships between bone protein and mineral in developing porcine long bone and calvaria.

Several proteins in the bone matrix have been implicated in the regulation of mineral crystal formation and growth. To investigate the relationships between these proteins and the mineral phase at various stages of mineral maturation, fetal porcine calvariae and long bones were fragmented and the particles (20 microm) separated by density gradient sedimentation into fractions of increasing density (1.8 to >2.2 g/cm3). Samples from each fraction were analyzed by X-ray diffraction to obtain the average crystal size/strain and chemical composition. Other samples were sequentially extracted, first with 4.0 mol/L guanidium hydrochloride (GuHCl) (G1), then with 0.5 mol/L ethylene-diamine tetraacetic acid (EDTA) (E), and again with 4.0 mol/L Gu-HCI (G2), for analysis of proteins in different tissue compartments. Based on the mineral density distribution and crystal size, fetal porcine bone protein content was determined for tissue residue and each extract and the protein composition analyzed by sodium dodecyl-polyacrylamide gel electrophoresis (SDS-PAGE). Although the insoluble organic matrix decreased with mineral density the collagen and protein content remained fairly constant, representing approximately 10% of the tissue weight, except in the highest density fraction. Whereas the total extractable protein, representing predominantly noncollagenous proteins, did not show density-related differences, differences were observed for individual proteins on SDS-PAGE. Consistent with their presence in osteoid, the content of bone sialoprotein (BSP), tyrosine-rich acidic matrix protein (TRAMP), and a series of small proteins with cell attachment properties in the G1 extract decreased with mineral density, whereas TRAMP and BSP were increased in G2 extracts. Mineral-associated proteins, including alpha2HS-glycoprotein, BSP, osteopontin (OPN), and osteocalcin, increased with mineral density, whereas secreted protein acidic and rich in cysteine (SPARC)/osteonectin, and some minor proteins, appeared to decrease. Differences of individual proteins within and between the calvarial and long bones could be related to the role of these proteins in the formation and maturation of hydroxyapatite crystals. Collectively, these studies demonstrate mineral density-associated changes in protein composition that reflect a rapid maturation of mineral crystals in embryonic porcine bones.

Animals↗

Drinking deep-sea water restores mineral imbalance in atopic eczema/dermatitis syndrome.

OBJECTIVE: The effect of drinking deep-sea water on hair minerals was studied in patients with atopic eczema/dermatitis syndrome (AEDS). Study of hair minerals revealed an imbalance of essential minerals and an increase in toxic minerals in AEDS patients. DESIGN: After drinking deep-sea water (Amami no Mizu) for 6 months in AEDS patients, hair minerals (essential minerals and toxic minerals), clinical evaluation of the skin symptoms were compared before drinking with after drinking. SUBJECTS: After obtaining informed consent, 33 patients (mean age 26 y, range 1-50 y, 13 male and 20 female subjects) with mild to moderate AEDS were enrolled. RESULTS: After drinking deep-sea water, the levels of the essential mineral, potassium (K), were significantly decreased, while the levels of selenium (Se) increased. On the other hand, drinking deep-sea water significantly decreased the levels of the toxic minerals, mercury and lead. Moreover, after drinking deep-sea water, the skin symptoms were improved in 27 out of 33 patients. CONCLUSION: These results indicate that the mineral abnormalities/imbalance may be involved in the pathogenesis of AEDS, and that drinking deep-sea water may be useful in the treatment of AEDS.

Adolescent↗

Serum levels of the fetuin-mineral complex correlate with artery calcification in the rat.

The present studies were carried out to evaluate the possible association between the presence of the fetuin-mineral complex in serum and vitamin D-induced artery calcification. The first experiment shows that there is a fetuin-mineral complex in the blood of rats in which extensive calcification of the artery media has been induced by treatment with vitamin D for 96 h, and that there is no detectable fetuin-mineral complex in the blood of rats in which artery calcification has been inhibited by concurrent treatment with ibandronate or osteoprotegerin. The second experiment shows that the timing of vitamin D-induced artery calcification correlates with the timing of the maximal increase in serum fetuin-mineral complex levels. Whereas both results indicate that serum levels of the fetuin-mineral complex are indeed associated with vitamin D-induced artery calcification, the biochemical basis for this association is presently unclear. One possibility is that high levels of the fetuin-mineral complex cause defects in the ability of fetuin to prevent the growth of the mineral component, which then seeds artery calcification. Another possibility is that the fetuin-mineral complex is the downstream product of a pathway that begins with the true causative agent, and that the serum level of the fetuin-mineral complex is a marker for the activity of this agent in blood. An unexpected finding of the present studies is that vitamin D-induced artery calcification is also correlated with a 65 to 75% reduction in serum fetuin, a reduction that appears to be caused by the clearance of the fetuin-mineral complex from serum.

Animals↗

The North/South Ireland Food Consumption Survey: mineral intakes in 18-64-year-old adults.

OBJECTIVE: To measure mineral intakes and the contribution of different food groups to mineral intakes in adults aged 18-64 years in Ireland. Intakes are reported for Ca, Mg, P, Fe, Cu and Zn. The adequacy of mineral intakes in the population and the risk of occurrence of excessive intakes are also assessed. DESIGN: Food consumption was estimated using a 7-day food diary for a representative sample (n=1379; 662 men, 717 women) of 18-64-year-old adults in the Republic of Ireland and Northern Ireland selected randomly from the electoral register. Mineral intakes (Ca, Mg, P, Fe, Cu and Zn) were estimated using tables of food composition. RESULTS: Mean nutrient density of intakes was higher for women than men for Ca and Fe and increased with age for all minerals, except Ca for men and Fe for women. Meat and meat products were the major contributor to mean daily intakes of Zn (38%), P (23%), Fe (18%), Cu (15%) and Mg (13%); dairy products (milk, yoghurt and cheese) to Ca (44%), P (22%), Zn (14%) and Mg (11%); bread and rolls to Fe (21%), Cu (18%), Ca and Mg (17%), Zn (13%) and P (12%); potatoes and potato products to Cu (16%), Mg (14%) and Fe (10%); and breakfast cereals to Fe (13%). In women of all ages nutritional supplements contributed 7.6%, 4.4%, 3.6% and 2.2% of mean daily intake of Fe, Zn, Cu and Ca, respectively, while in men of all ages, nutritional supplements contributed 2.7%, 2.3%, 1.7% and 0.6%, respectively, to mean daily intakes of Fe, Zn, Cu and Ca. Adequacy of minerals intakes in population groups was assessed using the average requirement (AR) as a cut-off value. A significant prevalence of intakes below the AR was observed for Ca, Fe, Cu and Zn but not P. A higher proportion of women than men had intakes below the AR for all minerals. Almost 50% of 18-50-year-old females had intakes below the AR for Fe, while 23%, 23% and 15% of women of all ages had intakes below the AR for Ca, Cu and Zn, respectively. For men of all ages, 11%, 8% and 13% had intakes below the AR for Ca, Cu and Zn, respectively. There appears to be little risk of excessive intake of Ca, Mg, P, Cu or Zn in any age/sex category. However, 2.9% of women of all ages had intakes above the tolerable upper intake level for Fe (45 mg) due to supplement use. CONCLUSION: Almost 50% of women aged 18-50 years had Fe intakes below the AR and relatively high proportions of women of all ages had intakes below the AR for Ca, Cu and Zn. With the possible exception of iron intake from supplements in women, there appears to be little risk of excessive intake of minerals in the adult population. Meat and meat products, dairy products (milk, cheese and yoghurt), bread and rolls, potatoes and potato products and breakfast cereals are important sources of minerals; nutritional supplements make only a small contribution to mineral intakes in the population as a whole but may contribute significantly to intakes among supplement users.

Adolescent↗

Analysis of mineral deposition in turkey tendons and self-assembled collagen fibers using mechanical techniques.

During limb movement and locomotion, animals store elastic energy in the tendons of the feet, legs, and other limbs. In the turkey, much of the force generated by the gastrocnemius muscle during locomotion is stored as elastic energy through deformation of the tendon. During growth and development, the leg tendons in some avians, including turkeys, mineralize and result in an increase in tensile strength and modulus. The purpose of our study was to evaluate the effects of mineralization on elastic energy storage and transmission in turkey tendons. Elastic and viscous stress-strain curves and elastic energy storage behavior were used to compare the behavior of mineralized turkey gastrocnemius tendons and mineralized self-assembled type I collagen fibers. Based on analysis of these two systems, we concluded that a simple mineralized fibrillar collagenous substrate can mimic the behavior of a more complex fibrillar collagenous substrate such as mineralized turkey tendon; however, the exact mechanism of mineralization may be different between the two substrates. Changes in mechanical properties of turkey tendon were consistent with a model in which mineralization appears to increase the effective collagen fibril length by efficiently transferring stress between neighboring collagen fibrils. Mineralization in self-assembled collagen fibers increased elastic energy storage less efficiently as compared with turkey tendon suggesting that the noncollagenous components of mineralizing tissue may act to promote collagen fibril to collagen fibril interactions.

Animals↗

Longitudinal microradiography: a non-destructive automated quantitative method to follow mineral changes in mineralised tissue slices.

This paper presents a new powerful method, longitudinal microradiography (LMR), with which it is possible to follow the mineral content in a de- or remineralizing carious tooth sample as a function of position on the surface of the mineralizing tissue independent of the sample thickness. Planoparallel tooth slices (thickness 300-400 microns) are cut parallel to the labial tooth surface and then fixed on a PMMA holder. Repeated microradiographic images of the same tissue slice together with an aluminium step wedge are made on photographic film at different times of mineralisation. The images are scanned under a densitometer with a microcomputer and the mineral content per unit tooth area at the same discrete tooth-slice surface positions is calculated (maximum predefined area is 5 mm x 5 mm, 15 x 15 positions). The change of mineral in one tooth slice per unit tooth surface area can be calculated at different times of mineralisation locally, as well as averaged over the total tooth-slice surface area. The SD in average mineral change is 0.009 kg m-2, which corresponds approximately to the mineral loss involved with a 8 microns deep tooth enamel carious lesion. All results are stored on disc. In an example, the enamel surfaces (6 mm2) of five human tooth enamel slices were exposed to an acetic acid buffer solution (pH 4.8) containing Ca, P and F. The mineral content variations in the enamel sample were followed in time by longitudinal microradiography. Mineral content evaluation shows in all cases a gradual increase in mineral loss. 3D plots of the mineral loss per unit area against tooth surface position at different stages of demineralisation of the same sample show an excellent uniform local behaviour in time with all tooth slices.

Dental Caries↗

Anomalies in mineralization of low concentrations of organic compounds in lake water and sewage.

The rates of mineralization of nitrilotriacetic acid (NTA), 2,4-dichlorophenoxyacetic acid (2,4-D), p-nitrophenol, aniline, and isopropyl N-phenylcarbamate (IPC) at one or more concentrations ranging from 100 pg/ml to 1.0 microgram/ml were proportional to chemical concentrations in samples of three lakes. The rates at 100 pg of NTA, 2,4-D, p-nitrophenol, and aniline per ml in samples of one or more lakes were less than predicted, assuming the rates were linearly related to the concentration. Neither NTA nor 2,4-dichlorophenol at 2.0 ng/ml was mineralized in some lake waters, but higher levels of the two chemicals were converted to CO2 in samples of the same waters. In samples from two lakes, little or no mineralization of IPC or 2,4-D occurred at 1.0 microgram/ml, but 10 ng/ml or lower levels of the herbicides were mineralized. The mineralization in sewage of 1.0 microgram of NTA per ml was biphasic; about 20% of the substrate was mineralized in 20 h, and mineralization was only reinitiated after a period of 130 h. The biphasic transformation was not a result of the accumulation of organic products, and it was still evident if protozoan activity was inhibited. NTA also underwent a biphasic mineralization in lake waters, and the biphasic pattern was not altered by additions of growth factors and inorganic nutrients. From 40 to 60% of the carbon of aniline added to lake water at levels of 100 pg/ml to 1.0 microgram/ml was mineralized, but more than 90% of the carbon of NTA, 2,4-D, or p-nitrophenol added to lake water at 10 ng/ml or 1.0 microgram/ml was mineralized.(ABSTRACT TRUNCATED AT 250 WORDS)

2,4-Dichlorophenoxyacetic Acid↗

A novel mineral flotation process using Thiobacillus ferrooxidans.

Oxidative leaching of metals by Thiobacillus ferrooxidans has proven useful in mineral processing. Here, we report on a new use for T. ferrooxidans, in which bacterial adhesion is used to remove pyrite from mixtures of sulfide minerals during flotation. Under control conditions, the floatabilities of five sulfide minerals tested (pyrite, chalcocite, molybdenite, millerite, and galena) ranged from 90 to 99%. Upon addition of T. ferrooxidans, the floatability of pyrite was significantly suppressed to less than 20%. In contrast, addition of the bacterium had little effect on the floatabilities of the other minerals, even when they were present in relatively large quantities: their floatabilities remained in the range of 81 to 98%. T. ferrooxidans thus appears to selectively suppress pyrite floatability. As a consequence, 77 to 95% of pyrite was removed from mineral mixtures while 72 to 100% of nonpyrite sulfide minerals was recovered. The suppression of pyrite floatability was caused by bacterial adhesion to pyrite surfaces. When normalized to the mineral surface area, the number of cells adhering to pyrite was significantly larger than the number adhering to other minerals. These results suggest that flotation with T. ferrooxidans may provide a novel approach to mineral processing in which the biological functions involved in cell adhesion play a key role in the separation of minerals.

Bacterial Adhesion↗

Mineral volume and morphology in carotid plaque specimens using high-resolution MRI and CT.

OBJECTIVE: High-resolution MRI methods have been used to evaluate carotid artery atherosclerotic plaque content. The purpose of this study was to assess the performance of high-resolution MRI in evaluation of the quantity and pattern of mineral deposition in carotid endarterectomy (CEA) specimens, with quantitative micro-CT as the gold standard. METHODS AND RESULTS: High-resolution MRI and CT were compared in 20 CEA specimens. Linear regression comparing mineral volumes generated from CT (VCT) and MRI (VMRI) data demonstrated good correlation using simple thresholding (VMRI=-0.01+0.98VCT; R2=0.90; threshold=4xnoise) and k-means clustering methods (VMRI=-0.005+1.38VCT; R2=0.93). Bone mineral density (BMD) and bone mineral content (BMC [mineral mass]) were calculated for CT data and BMC verified with ash weight. Patterns of mineralization like particles, granules, and sheets were more clearly depicted on CT. CONCLUSIONS: Mineral volumes generated from MRI or CT data were highly correlated. CT provided a more detailed depiction of mineralization patterns and provided BMD and BMC in addition to mineral volume. The extent of mineralization as well as the morphology may ultimately be useful in assessing plaque stability.

Adult↗

Leukemia inhibitory factor and oncostatin M influence the mineral phases formed in a murine heterotopic calcification model: a Fourier transform-infrared microspectroscopic study.

The study of bone mineralization processes is of considerable interest in understanding bone diseases and developing new therapies for skeletal disorders, particularly since bone homeostasis requires numerous cell types and a large cytokine network. Cell culture models of mineralization have often been used to study the cellular mechanisms of mineralization, but few data have been reported concerning the influence of extracellular matrix components and cytokines on the physicochemical properties of mineral. The purpose of this study was to analyze the effects of two cytokines, leukemia inhibitory factor (LIF) and oncostatin M (OSM), involved in bone metabolism on the physicochemical properties of bone mineral formed in a murine in vivo mineralization model. Murine bone marrow cells implanted under the kidney capsule in the presence or absence of cytokines led to heterotopic ossicle formation. A scanning electron microscopic microprobe revealed that heterotopic calcification had a lower (approximately 20%) Ca/P ratio after cytokine treatment as compared with the control without cytokine. Transmission electron microscopic analysis of cytokine-treated ossicles showed numerous areas with low mineral density, whereas electron diffraction pattern revealed an apatitic phase. These areas were not observed in the absence of cytokine. Moreover, Fourier transform-infrared microspectroscopy showed at the molecular level that the presence of either cytokine induced many microscopic areas in which short-range order organization, such as incorporation of carbonate and crystallinity/maturity of ossicle mineral, were modified. LIF and OSM influenced mineral phase formation in the present model and may thus be key protagonists in bone mineral development and skeletal diseases.

Animals↗

Lipoid pneumonia: a silent complication of mineral oil aspiration.

INTRODUCTION: Chronic constipation is a common symptom in pediatrics, and physicians often use mineral oil to treat chronic constipation in children. Mineral oil, a hydrocarbon, may not elicit a normal protective cough reflex and may impair mucociliary transport. These effects can increase the likelihood of its aspiration and subsequent impaired clearance from the respiratory tract. We report a case of a child with neurodevelopmental delay with chronic constipation and a history of chronic mineral oil ingestion presenting as asymptomatic exogenous lipoid pneumonia (ELP). CASE HISTORY: A 6-year-old white boy with a history of developmental delay was found to have an infiltrate in his right upper lobe on a chest radiograph obtained during evaluation for thoracic scoliosis. The patient had a long history of constipation with daily use of mineral oil. He was fed by mouth and had occasional episodes of coughing and choking during feeding. He was asymptomatic at presentation and physical examination was unremarkable. The patient was advised to stop administration of the mineral oil and was treated empirically with antibiotics during a 3-month period. At follow-up examination the patient continued to be asymptomatic, with the radiologic persistence of the infiltrate. Diagnosis of lipoid pneumonia was made by diagnostic bronchoscopy with bronchoalveolar lavage (BAL). The exogenous origin of the lipid in the BAL fluid was confirmed by gas chromatography/mass spectrometry. DISCUSSION: The clinical presentation of ELP is nonspecific and ranges from the totally asymptomatic patient with incidental radiologic finding, like our patient, to the patient with acute or chronic symptoms attributable to pneumonia, pulmonary fibrosis, or cor pulmonale. Bronchoscopy with BAL can be successful in establishing the diagnosis of ELP by demonstration of a high lipid-laden macrophage index. Treatment of ELP in children is generally supportive, with the symptoms and roentgenographic abnormalities resolving within months after stopping the use of mineral oil. CONCLUSION: Lipoid pneumonia as a result of mineral oil aspiration still occurs in the pediatric population. It can mimic other diseases because of its nonspecific clinical presentation and radiographic signs. In patients with swallowing dysfunction and pneumonia, a history of mineral oil use should be obtained and a diagnosis of ELP should be considered in the differential diagnoses if mineral oil use has occurred. Our case points to the need for increased awareness by the general pediatricians of the potential hazards of mineral oil use for chronic constipation.

Bronchoalveolar Lavage↗

Evaluation of the contents of mineral water, spring water, table water and spa water.

The present study surveys and evaluates the mineral contents of the speciality drinking waters currently available in Germany. A total of 257 producers and 226 reports of water contents have been consulted. The minerals sodium, calcium, potassium and magnesium together with the halogens chlorine and fluorine have been of special interest here in view of their significance in infant feeding, caries prevention, and possible influence on the drinking waters, the sodium concentrated from 0.9 mg/l (Finkenbachquelle, mineral water) to 12830 mg/l (Bad Mergentheimer Albertquelle, spa water). The potassium values also, range broadly, between 1.4 mg/l (Kisslegger Sprudel, mineral water) and 611 mg/l (Obenauer Löwensprudel, mineral water). Fluoride concentrations were given special attention, since they are of significance in caries prevention, for the strength of bones, and also considerable importance in connection with the danger of fluorosis. Numerous commercial mineral waters and table waters contain too little fluoride (0.007 mg/l, Kirkeler Waldquelle, mineral water) or have fluoride concentrations over 4.1 mg/l (Hardenstein Brunnen, mineral water). The latter appear inappropriate, especially for small children. On the basis of the considerable variations of mineral and halogen contents in commercial mineral waters and table waters, the concentration of crucial trace elements should be clearly stated on the labels of the bottles, along with relevant information concerning possible effects.

Drinking↗

Ovariectomy abolishes the normalization of femoral mineral content in 40-week-old female X-linked hypophosphatemic mice.

All young adult X-linked hypophosphatemic (Hyp) mice exhibit low bone mineral content. However, between the ages of 13 and 40 weeks, the female Hyp mice have an increase in bone mineral content per centimeter length to the level of the normal mice. Older Hyp male mice do not normalize in mineral content/length ratio. To explore the mechanisms for this, gonadectomy was performed in 3- to 4-week-old normal and Hyp mice to determine whether the increase in mineral content was related to gonadal secretions. Sham-operated and gonadectomized mice of both sexes and genotypes were sacrificed at 7, 13, and 40 weeks of age. Gonadectomy had little effect on the development of low mineral content in young adult Hyp mice. However, gonadectomy blocked the increase in femoral mineral content and mineral content/length ratio in Hyp female mice at 40 weeks of age. Gonadectomy blocked the increase in femoral mineral content in Hyp females while femoral length was increased somewhat. Femoral midshaft diameter was significantly smaller in Hyp female mice, which suggested a decrease in periosteal bone growth due to gonadectomy between 13 and 40 weeks of age. In general, plasma phosphate and calcium values could not be used to explain bone mineral increases since no consistent changes were found. In conclusion, the increase in bone mineral content which occurs in older Hyp female mice is dependent upon the presence of the ovary.

Absorption↗

Roles of alkaline phosphatase and labile internal mineral in matrix vesicle-mediated calcification. Effect of selective release of membrane-bound alkaline phosphatase and treatment with isosmotic pH 6 buffer.

The roles of alkaline phosphatase and labile internal mineral in matrix vesicle-mediated mineralization have been studied by selectively releasing the enzyme from a wide variety of matrix vesicle preparations using treatment with a bacterial phosphatidylinositol-specific phospholipase C and by demineralization of the vesicles using isosmotic pH 6 buffer. Following depletion of 50-90% of the alkaline phosphatase activity or treatment with citrate buffer, the vesicles were tested for their ability to accumulate 45Ca2+ and 32Pi from a synthetic cartilage lymph. Removal of alkaline phosphatase by phospholipase C treatment caused two principal effects, depending on the matrix vesicle preparation. In rapidly mineralizing vesicle fractions which did not require organic phosphate esters (Po) to accumulate mineral ions, release of alkaline phosphatase had only a minor effect. In slowly mineralizing vesicles preparations or those dependent on Po substrates for mineral ion uptake, release of alkaline phosphatase caused significant loss of mineralizing activity. The activity of rapidly calcifying vesicles was shown to be dependent on the presence of labile internal mineral, as demonstrated by major loss in activity when the vesicles were decalcified by various treatments. Ion uptake by demineralized vesicles or those fractionated on sucrose step gradients required Po and was significantly decreased by alkaline phosphatase depletion. Uptake of Pi, however, was not coupled with hydrolysis of the Po substrate. These findings argue against a direct role for alkaline phosphatase as a porter in matrix vesicle Pi uptake, contrary to previous postulates. The results emphasize the importance of internal labile mineral in rapid uptake of mineral ions by matrix vesicles.

Adenosine Monophosphate↗

Structural and composition studies on the mineral of newly formed dental enamel: a chemical, x-ray diffraction, and 31P and proton nuclear magnetic resonance study.

The present report describes a study of the development and maturation of the mineral component of dental enamel. We prepared porcine enamel of different stages of maturation, from the very immature enamel of unerupted teeth, with a mineral content of 45%, to fully mature enamel, with a mineral content of approximately 99%. We fractionated the less mature enamel by density centrifugation and examined the enamel density fractions and unfractionated enamel by a variety of chemical and physical techniques, including conventional and radial distribution function x-ray diffraction analysis, conventional and Fourier transform infrared spectroscopy, 31P and 1H nuclear magnetic resonance spectroscopy, and chemical analysis. The three most immature preparations, from unerupted teeth, had mineral contents of 45, 67, and 91 and Ca/P molar ratios of 1.41, 1.44, and 1.47. Density distribution histograms of the three fractions show that the early maturation of dental enamel mineral is accompanied by an increase in tissue density, reflecting the increase in mineral content. The density distribution in each sample is relatively narrow, indicating that the maturation process occurs at a fairly homogeneous rate, with all enamel in an anatomically defined zone mineralizing to about the same extent. X-ray diffraction studies indicate that even the least mature, least mineralized of these immature samples is considerably more crystalline than the most mature bone mineral studied and that crystalline perfection of the enamel crystals crystals increases further with maturation. Both the a and c axes of the mineral unit cell expand significantly during early stages of maturation. Solid-state 31P nuclear magnetic resonance spectroscopy studies indicate that dental enamel contains a DCPD-like HPO4 component in an apatitic lattice, similar to the component previously observed in bone and some synthetic calcium phosphates. The proportion of this DCPD-like component decreases with maturation but is readily detectable even in fully mature enamel. The infrared spectroscopic studies indicate that the 3570 cm-1 band ascribed to the OH- group of the hydroxyapatite crystals is absent in the least mature enamel but can be detected and becomes progressively stronger as the enamel becomes more mature. The increase in the content of the OH- groups of the apatite crystals is concomitant with the observed increase in unit cell parameters. Similar studies on very young and very old mature bone of four different species failed to detect the presence of OH- groups.

Aging↗