Distinct actions of strontium on mineral formation in matrix vesicles.

Matrix vesicles (MVs) are involved in the initial step of mineralization in skeletal tissues and provide an easily model to analyze the hydroxyapatite (HA) formation. Sr stimulates bone formation and its effect was tested on MVs. Sr(2+) (15-50 microM) in the mineralization medium containing MVs, 2 mM Ca(2+) and 3.

A comparative analysis of strategies for isolation of matrix vesicles.

Matrix vesicles (MVs) are extracellular organelles involved in the initial steps of mineralization. MVs are isolated by two methods. The first isolation method of MVs starts with collagenase digestion of osseous tissues, followed by two differential centrifugations.

Phosphodiesterase activity of alkaline phosphatase in ATP-initiated Ca(2+) and phosphate deposition in isolated chicken matrix vesicles.

Inorganic pyrophosphate is a potent inhibitor of bone mineralization by preventing the seeding of calcium-phosphate complexes. Plasma cell membrane glycoprotein-1 and tissue nonspecific alkaline phosphatase were reported to be antagonistic regulators of mineralization toward inorganic pyrophosphate formation (by plasma cell membrane glycoprotein-1) and degradation (by tissue nonspecific alkaline phosphatase) under physiological conditions. In addition, they possess broad overlapping enzymatic functions.

The roles of annexins and alkaline phosphatase in mineralization process.

In this review the roles of specific proteins during the first step of mineralization and nucleation are discussed. Mineralization is initiated inside the extracellular organelles-matrix vesicles (MVs). MVs, containing relatively high concentrations of Ca2+ and inorganic phosphate (Pi), create an optimal environment to induce the formation of hydroxyapatite (HA).

Chick embryo anchored alkaline phosphatase and mineralization process in vitro.

Bone alkaline phosphatase with glycolipid anchor (GPI-bALP) from chick embryo femurs in a medium without exogenous inorganic phosphate, but containing calcium and GPI-bALP substrates, served as in vitro model of mineral formation. The mineralization process was initiated by the formation of inorganic phosphate, arising from the hydrolysis of a substrate by GPI-bALP. Several mineralization media containing different substrates were analysed after an incubation time ranging from 1.

Activity increase after extraction of alkaline phosphatase from human osteoblastic membranes by nonionic detergents: influence of age and sex.

The solubilization of alkaline phosphatase (AP) from osteoblastic cell membranes obtained from human primary bone cell cultures was studied according to the age and sex of the donors (17 females, 11 males; age range: 2-77 years). Cell membranes were treated by non-ionic (n-octyl beta-D-glucopyranoside, OG), ionic or zwitterionic detergents, then centrifuged. When OG was used almost all the AP was solubilized.

Differential solubilization of osteoblastic alkaline phosphatase from human primary bone cell cultures.

Mineralization of cartilage and bone requires alkaline phosphatase activity. In order to study the enzymatic properties of bone alkaline phosphatase in bone disease and more particularly in patients with osteoporosis and osteoarthritis, we investigated the solubilization of alkaline phosphatase from primary bone cell cultures derived from human bone explants. To study the release of alkaline phosphatase from membranes, several detergents at a concentration above the critical micellar concentration and cholesterol were used.

Studies on the mechanism of different collagen glucosyltransferase reactions (Golgi apparatus, smooth endoplasmic reticulum, rough endoplasmic reticulum) in chick embryo liver.

1. The galactosylhydroxylysylglucosyltransferase (GGT) specific to collagen is located in the RER (rough endoplasmic reticulum), SER (smooth endoplasmic reticulum) and Golgi apparatus for the chick embryo liver. 2.

Characterization and purification of culture-derived soluble glycoproteins of Babesia canis.

The addition of [14C]-glucosamine to media of Babesia canis cultures causes the appearance of labeled glycoproteins in the culture supernatants. These radioactive soluble glycoproteins were separated according to their molecular weight by gel filtration and according to their (acidic) pI by preparative electrofocusing. The labeled fractions were then analyzed by SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis).

[Quantitative analysis of a tetraribonucleotide mixture by ultraviolet spectrophotometry].

Using the least squares method we have calculated the proportions of each nucleotide of a mixture of AMP, CMP, GMP and UMP, after measuring the absorbance of the mixture every ten nanometers from 230 to 290 nm at pH 12.7 and 2. The method is very simple and rapid (the calculations are made in less than one minute), does not require a highly sensitive spectrophotometer to obtain reasonably precise results and, in contrast to the other methods of the literature, it can be applied to quantities as little as 50 micrograms of nucleotides.

[Simple method for preparation of rat liver DNA].

The frozen tissue was sliced and then homogenized at 20 degree C in LiCl, 2 M; lauryl-trimethyl ammonium chloride (K & K No. 4484), 5%; pronase, B grade (calbiochem), 1 mg/ml and Tris-HCl 10 mM pH 7.5.

[Rapid technic for preparation of thyroid ribonucleic acids without phenol].

Thyroid tissue was homogenized in 2 M LiCl. The homogenate was alloued to stand 1 h 30 min at 2 degrees C and then centrifuged. The pellet was suspended in 5% triisopropylnaphthalene sulfonic acid (the sodium salt), 0.

[Isolation and characterization of beef thyroid giant RNA].

Total HMW-RNAs were prepared by three different methods (method with phenol, method with NaClO4, method without phenol using Ultrogel AcA 22 filtration). Giant RNAs were obtained in the void volume by filtration on Sepharose 2B. The giant RNAs/total HMW-RNA ratio is higher (6.

Ribosomal and transfer RNA contents of the normal and pathologic human thyroid gland.

One hundred and seventy seven pieces of normal or pathologic thyroid tissue from 17 patients were assayed for rRNA, tRNA and DNA content. The tRNA/DNA and rRNA/DNA ratios in pathologic tissue were statistically compared with the same ratios in normal tissue. In toxic adenoma (5 cases) and anoplastic cancer (2 cases), both ratios were increased.