Calcified Tissue Research最新文献

Variations in the composition of bone and tooth mineral are consistent with the model that the constituents are a mixed microcrystalline apatite (AP)-octocalcium phosphate (OCP) like phase and an amorphous or submicrocrystalline calcium phosphate (ACP) like phase whereby these phases can occur in different proportions. An appropriate model for a description of the variable composition and the solubility behavior of the apatite phase is given by the formula (formula: see text) in which the compositional parameters x, y, z, and u each account for one type of defect mechanism. Other point defects are formed as well by incorporation of minority amounts of ions such as Cl-, K+, and F-; a number of trace elements can substitute for Ca2+ ions under in vivo conditions. It is suggested that the incorporation of ions in or loss from the crystals in contact with aqueous solutions is reversible. Literature data are used to show the direction in which the solubility product of the apatite phase shifts by incorporation of the different physiologically relevant ions. A quantitative evaluation of the available literature data revealed that Na+ and CO3= incorporation is the main cause for shifts in the solubility product of biological apatites.

Osteoporosis has been reported to complicate androgen deficiency in males. Accordingly, we have evaluated an osteoporotic hypogonadal male with bone histomorphometry before and after 6 months of testosterone replacement. Androgen therapy resulted in increases in relative osteoid volum, total osteoid surface, linear extent of bone formation, and bone mineralization. The dramatic histological response to hormonal replacement confirms the importance of androgens in bone modeling and remodeling.

Extracellular masses of crystals are present in the endosternite of certain opilions (Phalangium, Odiellus, and Leiobunum). X-ray spectrography and secondary-ion analysis have shown them to be rich in calcium but poor in phosphorus and other elements. The associated anion has not been identified, but is most probably organic in nature and perhaps an oxalate.

We studied 173 patients with Paget's disease and 105 patients with hyperparathyroidism. Nine patients were found to have both disorders.

Types of "H2O" in human enamel and in precipitated apatites are characterized using X-ray diffraction, infrared (IR) absorption spectroscopic and thermogravimetric analyses. Changes in lattice parameters (principally in the a-axis dimensions) and in the character of the IR absorption bands are correlated with weight losses at pyrolysis temperatures of 100 degrees to 400 degrees C and with effect of rehydration and reignition of previously ignited samples. This study demonstrated that the loss of "H2O" below 200 degrees C is reversible and causes no significant change in the lattice parameter of these apatites, whereas loss of "H2O" between 200 degrees and 400 degrees C is irreversible and causes a contraction in the a-axis dimension. It is proposed that two general types of "H2O" are present in these apatites: (a) adsorbed H2O--characterized by reversibility, thermal instability below 200 degrees C, and lack of effect on lattice parameters; and (b) lattice H2O--characterized by irreversibility, thermal instability between 200 and 400 degrees C, and induction of expansion in the a-axis dimensions of human enamel and precipitated apatites. Lattice H2O is assumed to be due to H2O-for-OH and/or HPO4-for-PO4 substitutions in these apatites. Loss of adsorbed H2O caused sharpening of the OH absorption bands in the spectra of these apatites. Loss of lattice H2O caused the appearance of P-O-P absorption bands (due to the presence of P2O74- group) in precipitated apatites containing small amounts of CO32-.

Fluoride 27 mg was given perorally to 14 subjects. It was found that the serum fluoride concentration increased followed by a decrease to normal levels during 24 h. Serum concentrations of calcium and phosphate decreased initially whereas those of serum immunoreactive parathyroid hormone increased. After 24 h the measured quantities were within normal limits. The results are discussed with reference to mineralization of hard tissues and to fluoride treatment of osteoporotic patients.

The evolution of the mineral constituents of subcutaneous calcinosis induced in rats by topical calciphylaxis was studied by the method of quantitative chemical analysis, and after treatment with excited gases by electron spin resonance (ESR) analysis. Chemical data show that the genesis of the subcutaneous calcinosis does not significantly alter the concentration of Ca, P, F, CO3, Mg, and Fe in the mineral phase of the femoral bone of calciphylactic rats. In the calcinosis an important increase of the fluoride concentration is noticed in function of the time after challenging. There is also a high concentration of Mg2+ ions in the early stages of the experimental calcification. Iron injected for the challenging is continuously present in the calciphylactic tissue after this treatment. This suggests that subcutaneous calcinosis might be a means of fixing certain heavy metal ions. After treatment with excited gases, the proportions of the trapped CO33- and O3- radicals are of the same order of magnitude in calciphylactic tissue after 12 days and observations in bone mineral. These suggest that after 12 days the mineral of the calciphylactic tissue has a crystalline state close to that of bone.

Pig epiphyseal cartilage (proximal ulna epiphysis) previously incubated into vitro in the presence of sodium [35S]sulfate or [3H]thymidine was either analyzed by autoradiography or separated into 9 morphologically defined consecutive layers and investigated for 35S-incorporation into the guanidinium chloride-extractable proteoglycans and for lysozyme activity. The lowest 35S incorporation and lysozyme activity were determined in the zone of resting cells, but there is a consecutive increase in the rate of proteoglycan synthesis and lysozyme activity toward the diaphyseal cartilage-bone junction, with the maximum at the lower columnar cell zone and a sharp reduction of both parameters at the hypertrophic zone. The maxima of 35S incorporation and [3H]thymidine incorporation do not coincide. The guanidinium chloride-soluble proteoglycans exhibit macromolecular polydispersity. Fractions excluded from as well as retarded by Sepharose 2B gel could be separated and were detected in all zones. The results indicate a correlation of proteoglycan biosynthesis and lysozyme activity in epiphyseal cartilage.