Alterations in phosphorus, calcium and PTHrP contribute to defects in dental and dental alveolar bone formation in calcium-sensing receptor-deficient mice.

To determine whether the calcium-sensing receptor (CaR) participates in tooth formation and dental alveolar bone development in mandibles in vivo, we examined these processes, as well as mineralization, in 2-week-old CaR-knockout (CaR(-/-)) mice. We also attempted to rescue the phenotype of CaR(-/-) mice by genetic means, in mice doubly homozygous for CaR and 25-hydroxyvitamin D 1alpha-hydroxylase [1alpha(OH)ase] or parathyroid hormone (Pth). In CaR(-/-) mice, which exhibited hypercalcemia, hypophosphatemia and increased serum PTH, the volumes of teeth and of dental alveolar bone were decreased dramatically, whereas the ratio of the area of predentin to total dentin and the number and surface of osteoblasts in dental alveolar bone were increased significantly, as compared with wild-type littermates. The normocalcemia present in CaR(-/-);1alpha(OH)ase(-/-) mice only slightly improved the defects in dental and alveolar bone formation observed in the hypercalcemic CaR(-/-) mice. However, these defects were completely rescued by the additional elimination of hypophosphatemia and by an increase in parathyroid hormone-related protein (PTHrP) expression in the apical pulp, Hertwig's epithelial root sheath and mandibular tissue in CaR(-/-); Pth(-/-) mice. Therefore, alterations in calcium, phosphorus and PTHrP contribute to defects in the formation of teeth and alveolar bone in CaR-deficient mice. This study indicates that CaR participates in the formation of teeth and in the development of dental alveolar bone in mandibles in vivo, although it appears to do so largely indirectly.

Effect of the Ca/P ratio on the dielectric properties of nanoscaled substoichiometric hydroxyapatite.

Nanoscaled hydroxyapatite (n-HAp) was prepared by a wet chemical precipitation method, pressed to pellets and sintered at various temperatures between 900 and 1200 degrees C. With input stoichiometries of Ca/P ratios between 1.4 and 2.0, compositions in the substoichiometric range of Ca/P between 1.45(1) and 1.62(3) were determined after preparation. After sintering, final values of the Ca/P ratio between 1.45(8) and 1.66(4) were found. Capacitances and dielectric losses were determined in the frequency range between 20 Hz and 1 MHz and dielectric constants calculated from the capacitances. Dependencies of the dielectric properties on the composition, as well as on sintering temperature and frequencies were investigated. The dielectric constants generally tend to increase with increasing Ca-content. Different behaviour was observed for low frequencies (below 10(3) Hz) and for compositions far from the stoichiometric point of hydroxyapatite (Ca/P: 1.67). Comparable results were found for dielectric losses.

Steel slag amendment impacts on soil microbial communities and activities of rice (Oryza sativa L.).

With the increase in iron/steel production, the higher volume of by-products (slag) generated necessitates its efficient recycling. Because the Linz-Donawitz (LD) slag is rich in silicon (Si) and other fertilizer components, we aim to evaluate the impact of the LD slag amendment on soil quality (by measuring soil physicochemical and biological properties), plant nutrient uptake, and strengthens correlations between nutrient uptake and soil bacterial communities. We used 16 S rRNA illumine sequencing to study soil bacterial community and APIZYM assay to study soil enzymes involved in C, N, and P cycling. The LD slag was applied at 2 Mg ha-1 to Japonica and Indica rice cultivated under flooded conditions. The LD slag amendment significantly improved soil pH, plant photosynthesis, soil nutrient availability, and the crop yield, irrespective of cultivars. It significantly increased N, P, and Si uptake of rice straw. The slag amendment enhanced soil microbial biomass, soil enzyme activities and enriched certain bacterial taxa featuring copiotrophic lifestyles and having the potential role for ecosystem services provided to the benefit of the plant. The study evidenced that the short-term LD slag amendment in rice cropping systems is useful to improve soil physicochemical and biological status, and the crop yield.

Serum phosphorus during the menstrual cycle.

In the continuing search for a simple, noninvasive, reliable method to detect ovulation, phosphorus (P) levels have been measured in women across a menstrual cycle. Salivary P has been reported to increase significantly in women periovulatory. Reports of serum P show no such periovulatory peak. We measured serum P in nine ovulatory and two anovulatory women during one menstrual cycle. Indirect indicators of ovulation were biphasic BBT curve and luteal phase serum progesterone more than 3 ng/ml. No significant periovulatory change in serum P was found, only small fluctations ranging from 0.99--2.76 mg/dl. The absence of a periovulatory serum phosphorus peak in this and other investigations of serum P suggests that if there is altered P metabolism during the menstrual cycle, it is not reflected in the serum. Other mechanisms, such as urinary or salivary excretion, may be operating to maintain serum P within the physiological range. This hypothesis needs to be explored.

PIP: Phosphorus levels were measured in sera throughout a menstrual cycle to determine if such measurements would provide a noninvasive means of detecting ovulation. Previous reports have established a periovulatory peak for salivary phosphorus, but no such elevation has been shown before for serum phosphorus, so this study examined changes in the serum level. 11 women, 9 ovulatory and 2 anovulatory were studied for 1 menstrual cycle. Serum samples for phosphorus determination were taken every other day; levels of serum phosphorus were compared with more conventional indicators of ovulation, such as basal body temperature increase at luteal phase and increased serum progesterone from 3 ng/ml or more. Small fluctuations were found (range, .99-2.76 mg/dl) in serum phosphorus but no periovulatory peak was determined. Since other studies have demonstrated a peak in salivary phosphorus, it is hypothesized that phosphorus changes do occur coupled with ovulation, but that these changes are not reflected in serum. The hypothesis of phosphorus metabolism change in relation to ovulation needs further research.