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J D Termine

Publications and source records attributed to J D Termine.

7 recordsLinked to original sources
PubMed1979

Enamel matrix: structural proteins.

Cell-free, fetal bovine enamel tissue was examined intact by high resolution. 13C Fourier transform, nuclear magnetic resonance spectroscopy. Two types of protein chains were observed under these conditions, one exhibiting rapid mobility and accounting for approximately two-thirds of the enamel matrix, while the other exhibited restricted or anisotropic segmental motion and accounted for the remaining third of the matrix. Sequential extraction of this fetal enamel under non-degradative conditions with dissociative solvents yielded two biochemically distinct populations of matrix protein. As expected, the bulk of the matrix consisted of proline-rich amelogenins, although the SDS-gel electrophoresis molecular weights for these proteins were somewhat higher than those reported using other extraction methods. Approximately fifteen percent of the total matrix consisted of much higher molecular weight phosphoproteins (46,000-72,000 daltons) whose amino acid composition closely resembled that reported for mature enamel protein. These high molecular weight proteins were tightly bound to the fetal enamel apatite crystallites.

Animals↗
PubMed1976

Inhibition of apatite formation by phosphorylated metabolites and macromolecules.

Apatite formation from synthetic extracellular fluids is rate-limited both at the initial amorphous precursor deposition step and at the amorphous-crystalline transformation reaction. Nucleotide diphosphates and triphosphates and low molecular weight metabolites containing two attached ester phosphate groups all inhibited amorphous-crystalline conversion at concentrations of 10(-5) to 10(-6)M. Both native and synthetic polynucleotides as well as the phosphoproteins from rat dentin or egg yolk also inhibited crystal formation from amorphous calcium phosphate. In all cases, substantial amounts of inhibitor molecules were incorporated into the stabilized amorphous precipitates. Treatment of isolated, inhibitor-stabilized amorphous precipitates with hydrolytic enzymes such as alkaline phosphatase or papain reversed the inhibitory effect and permitted crystallization to proceed normally.

Alkaline Phosphatase↗
PubMed1976

Comparative studies of intra- and extramitochondrial calcium phosphates from the hepatopancreas of the blue crab (Callinectes sapidus).

Subcellular fractions of cytoplasmic mineral granules and mineral-loaded mitochondria were isolated from whole homogenates of hepatopancreas of the blue crab (Callinectes sapidus). Chemical, physical, and morphologic studies were carried out on both subcellular fractions, with and without prior removal of organic components by hydrazine extraction. In contrast to cytoplasmic granules, whole mitochondria contained appreciable amounts of mineral ions not associated with a solid mineral phase. Quantitative analyses and infrared spectroscopy showed cytoplasmic and mitochondrial mineral phases to be calcium phosphates of similar but not identical composition. Both cytoplasmic and mitochondrial mineral phases, as in synthetic amorphous calcium phosphate, show noncrystalline patterns when examined by infrared spectroscopy and x-ray diffraction, and a common ultrastructure of clustered spheres of approximately 100 A diameter. The findings suggest that amorphous calcium phosphate in biological systems may exhibit appreciable variation in Ca/P and in the content of foreign ions such as Mg2+, ADP, and ATP. A mitochondriogenic mechanism of calcification could not be confirmed nor refuted by this study.

Animals↗
PubMed1975

Experimental renal osteodystrophy. The response to 25-hydroxycholecalciferol and dicholomethylene diphosphate therapy.

Bone mineral and matrix maturation in chronically uremic, nonacidotic rats were investigated after 25-hydroxcholecalciferol (25OHD) and/or dichloromethylene diphosphonate (C12MDP) therapy utilizing bromoform-toluene density gradient fractionation and X-ray diffraction analyses. The bromoform-toluene density gradient analyses demonstrated that the progressive accumulation of less dense, more immature bone characteristic of progressive uremia was reversed by 25OHD and/or C12MDP therapy for a 2-wk period, and that after 4 wk of therapy the maturational profile of bones from chronically uremic animals treated with 250HD and/or C12MDP was comparable to that from nonuremic littermates. X-ray diffraction analysis revealed that by the 4th wk of therapy with 25OHD and C12MDP both the degree of crystallinity and the crystal size/perfection parameters in the uremic bones were comparable to those of nonuremic, pair-fed control littermates. Treatment for 4 wk with 25OHD resulted in enlarged and/or more perfect apatite crystallites, while C12MDP alone slightly inhibited crystal growth and/or perfection after 2 wk of treatment. Soft tissue calcification was diminished in uremic animals treated for 4 wk with C12MDP or a combined C2MDP/25OHD regimen, the latter being much more effective in this regard. The accumulated data in this study support the premise that the attendant accelerated bone resorption, soft tissue calcification, and abnormal mineralization and maturation of the skeletal tissue, well documented to characterize experimental ranal insufficiency, may be alleviated with therapeutic dosages of 25OHD and/or C12MDP.

Animals↗