Octacalcium Phosphate as a Precursor in Biomineral Formation

1987 ◽  
Vol 1 (2) ◽  
pp. 306-313 ◽  
Author(s):  
W.E. Brown ◽  
N. Eidelman ◽  
B. Tomazic
Keyword(s):  
Thermogravimetric Analysis ◽  
Calcium Phosphates ◽  
Three Dimensional ◽  
Octacalcium Phosphate ◽  
Basic Form ◽  
Vacancy Defects ◽  
Impurity Ions

What are biominerals and how are they formed? It is usually assumed: (i) that the prototype for most apatitic biominerals is hydroxyapatite (OHAp), Ca5(PO4) 3OH; and (ii) that the OHAp structure has been modified by the presence of impurity ions and vacancy defects in specific OHAp lattice sites. The usual answer, at least implicitly, to the second question is that the apatitic mineral is formed directly by the precipitation of ions from the surrounding solution. Our answers are: (i) that apatitic biominerals are formed through a precursor mechanism in which octacalcium phosphate (OCP), Ca8H 2(PO4)6·5H2O, precipitates first and then hydrolyzes ireversibly in situ to a transition product intermediate to OCP and OHAp; and (ii) that this product, "octacalcium phosphate hydrolyzate" (OCPH), may contain (a) OHAp-like and OCP-like domains in varying amounts, (b) vacancy defects and impurity ions in lattice sites in these domains, and (c) various kinds of one-, two-, and three-dimensional defects which are not present in either the OHAp or the OCP lattice, these defects being formed during the in situ hydrolysis step. A calcification model of this type was first proposed in 1957, but full acceptance was delayed because most of the evidence was circumstantial and in vitro in nature. The situation has changed radically because of three unrelated studies that are in vivo in nature but lead to the same conclusion: I. 32P-pyrolysis studies of rat enamel: The results clearly demonstrated that an acidic calcium phosphate precursor was involved. II. Precipitation of calcium phosphates in serum. Ultrafiltered serum was equilibrated with brushite. Subsequent changes in the ionic concentrations revealed that OCP was formed at first and then hydrolyzed to a more basic form, OCPH, but never reached the solubility of OHAp. III. Physicochemical properties of cardiovascular biominerals: We recently characterized biominerals in cardiovascular deposits in an encompassing variety of ways. As an overall conclusion, OCPH was the prototype most compatible with the data [including indices of refraction, solubility, P2O74- formation on pyrolysis, thermogravimetric analysis (TGA) measurements, presence of water, and incorporation of CO32-, Na+, and Mg2+]. This calcification model has important consequences relative to all kinds of calcification and decalcification processes, including those of enamel.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

A Comparative Study of Bioceramics In Vitro and In Vivo

2005 ◽  
Vol 284-286 ◽  
pp. 11-14 ◽  
Author(s):  
Yang Leng ◽  
Ren Long Xin ◽  
Ji Yong Chen
Keyword(s):  
Calcium Phosphates ◽  
Glass Ceramics ◽  
Octacalcium Phosphate ◽  
Rabbit Muscle ◽  
In Vivo Experiments ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Dental Applications

Bioactive calcium phosphate (Ca-P) formation in bioceramics surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The examined bioceamics included most commonly used bioglass®, A-W glass-ceramics and calcium phosphates in orthopedic and dental applications. The Ca-P cyrstal structures were examined with single crystal diffraction patterns in transmission electron microscopy, which reduced possibility of misidentifying Ca-P phases. The experimental results show that capability of Ca-P formation considerably varied among bioceramics, particularly in vivo. Octacalcium phosphate (OCP) was revealed on the all types of bioceramics in vitro and in vivo experiments. This work leads us to rethink how to evaluate bioactivity of bioceramics and other orthopedic materials which exhibit capability of osteoconduction by forming direct bonding with bone.

scholarly journals Live 3D imaging and mapping of shear stresses within tissues using incompressible elastic beads

2021 ◽  
Author(s):  
Alexandre SOUCHAUD ◽  
Arthur BOUTILLON ◽  
Gaëlle CHARRON ◽  
Atef ASNACIOS ◽  
Camille NOÛS ◽  
...  
Keyword(s):  
Shear Stress ◽  
Covalent Binding ◽  
Three Dimensional ◽  
Contour Method ◽  
Shear Stresses ◽  
Liquid Droplets ◽  
Mechanical Constraints

To investigate the role of mechanical constraints in morphogenesis and development, we develop a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane (PDMS) mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate and submitted to uniaxial compression. The local shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the Zebrafish embryo during gastrulation, our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue, and its time evolution.

scholarly journals Structure of hibernating ribosomes studied by cryoelectron tomography in vitro and in situ

2010 ◽  
Vol 190 (4) ◽  
pp. 613-621 ◽  
Author(s):  
Julio O. Ortiz ◽  
Florian Brandt ◽  
Valério R.F. Matias ◽  
Lau Sennels ◽  
Juri Rappsilber ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Spatial Organization ◽  
Three Dimensional ◽  
E Coli ◽  
Escherichia Coli Cells ◽  
Three Dimensional Configuration

Ribosomes arranged in pairs (100S) have been related with nutritional stress response and are believed to represent a “hibernation state.” Several proteins have been identified that are associated with 100S ribosomes but their spatial organization has hitherto not been characterized. We have used cryoelectron tomography to reveal the three-dimensional configuration of 100S ribosomes isolated from starved Escherichia coli cells and we have described their mode of interaction. In situ studies with intact E. coli cells allowed us to demonstrate that 100S ribosomes do exist in vivo and represent an easily reversible state of quiescence; they readily vanish when the growth medium is replenished.

scholarly journals Three-dimensional ultrastructure of the septin filament network inSaccharomyces cerevisiae

2012 ◽  
Vol 23 (3) ◽  
pp. 423-432 ◽  
Author(s):  
Aurélie Bertin ◽  
Michael A. McMurray ◽  
Jason Pierson ◽  
Luong Thai ◽  
Kent L. McDonald ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Yeast Cells ◽  
Lipid Monolayers ◽  
Morphological Description ◽  
Section Electron ◽  
Subunit Organization

Septins are conserved GTP-binding proteins involved in membrane compartmentalization and remodeling. In budding yeast, five mitotic septins localize at the bud neck, where the plasma membrane is enriched in phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2). We previously established the subunit organization within purified yeast septin complexes and how these hetero-octamers polymerize into filaments in solution and on PtdIns4,5P2-containing lipid monolayers. How septin ultrastructure in vitro relates to the septin-containing filaments observed at the neck in fixed cells by thin-section electron microscopy was unclear. A morphological description of these filaments in the crowded space of the cell is challenging, given their small cross section. To examine septin organization in situ, sections of dividing yeast cells were analyzed by electron tomography of freeze-substituted cells, as well as by cryo–electron tomography. We found networks of filaments both perpendicular and parallel to the mother–bud axis that resemble septin arrays on lipid monolayers, displaying a repeat pattern that mirrors the molecular dimensions of the corresponding septin preparations in vitro. Thus these in situ structures most likely represent septin filaments. In viable mutants lacking a single septin, in situ filaments are still present, although more disordered, consistent with other evidence that the in vivo function of septins requires filament formation.

scholarly journals Hydroxyapatite for Biomedical Applications: A Short Overview

Ceramics ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 542-563
Author(s):  
Elisa Fiume ◽  
Giulia Magnaterra ◽  
Abbas Rahdar ◽  
Enrica Verné ◽  
Francesco Baino
Keyword(s):  
Calcium Phosphates ◽  
Three Dimensional ◽  
Good Alternative ◽  
Great Promise ◽  
Comprehensive Overview ◽  
Current Trends ◽  
Mechanical Performances ◽  
Potential Use

Calcium phosphates (CaPs) are biocompatible and biodegradable materials showing a great promise in bone regeneration as good alternative to the use of auto- and allografts to guide and support tissue regeneration in critically-sized bone defects. This can be certainly attributed to their similarity to the mineral phase of natural bone. Among CaPs, hydroxyapatite (HA) deserves a special attention as it, actually is the main inorganic component of bone tissue. This review offers a comprehensive overview of past and current trends in the use of HA as grafting material, with a focus on manufacturing strategies and their effect on the mechanical properties of the final products. Recent advances in materials processing allowed the production of HA-based grafts in different forms, thus meeting the requirements for a range of clinical applications and achieving enthusiastic results both in vitro and in vivo. Furthermore, the growing interest in the optimization of three-dimensional (3D) porous grafts, mimicking the trabecular architecture of human bone, has opened up new challenges in the development of bone-like scaffolds showing suitable mechanical performances for potential use in load bearing anatomical sites.

scholarly journals Live 3D imaging and mapping of shear stresses within tissues using incompressible elastic beads

Development ◽  
2022 ◽  
Author(s):  
Alexandre Souchaud ◽  
Arthur Boutillon ◽  
Gaëlle Charron ◽  
Atef Asnacios ◽  
Camille Nous ◽  
...  
Keyword(s):  
Shear Stress ◽  
Covalent Binding ◽  
Three Dimensional ◽  
Contour Method ◽  
Shear Stresses ◽  
Liquid Droplets ◽  
Mechanical Constraints

To investigate the role of mechanical constraints in morphogenesis and development, we develop a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane (PDMS) mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate submitted to uniaxial compression. Thelocal shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the Zebrafish embryo during gastrulation,our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue.

scholarly journals The behavior of fibroblasts from the developing avian cornea. Morphology and movement in situ and in vitro.

1975 ◽  
Vol 67 (2) ◽  
pp. 400-418 ◽  
Author(s):  
J B Bard ◽  
E D Hay
Keyword(s):  
Three Dimensional ◽  
Cell Movement ◽  
Cell Process ◽  
General Mechanism ◽  
Dividing Cells ◽  
Collagenous Stroma ◽  
Collagen Lattices

The early chick cornea is composed of an acellular collagenous stroma lined with an anterior epithelium and a posterior endothelium. At stage 27-28 of development (5 1/2 days), this stroma swells so that the cornea is 75-120 mum thick. At the same time, fibroblasts that originate from the neural crest begin to invade this stroma. Using Nomarski light microscopy, we have compared the behavior of moving cells in isolated corneas with the migratory activities of the same cells in artificial collagen lattices and on glass. In situ, fibroblasts have cyclindrical bodies from which extend several thick pseudopodia and/or finer filopodia. Movement is accompanied by activity in these cytoplasmic processes. The flat ruffling lamelli-podia that characterize these cells on glass are not seen in situ, but the general mechanism of cell movement seems to be the same as that observed in vitro: either gross contraction or recoil of the cell body (now pear shaped) into the forward cell process, or more subtle "flowing" of cytoplasm into the forward cell process without immediate loss of the trailing cell process. We filmed collisions between cells in situ and in three-dimensional collagen lattices. These fibroblasts show, in their pair-wise collisions, the classical contact inhibition of movement (CIM) exhibited in vitro even though they lack ruffled borders. On glass these cells multi-layer, showing that, while CIM affects cell movement, fibroblasts can use one another as a substratum. Postmitotic cells show CIM in moving away from each other. Interestingly, dividing cells in situ do not exhibit surface blebbing, but do extend filopodia at telophase. The role of CIM in controlling cell movement in vivo and in vitro is stressed in the discussion.

scholarly journals Synthesis of Thermal Polymerizable Alginate-GMA Hydrogel for Cell Encapsulation

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaokun Wang ◽  
Tong Hao ◽  
Jing Qu ◽  
Changyong Wang ◽  
Haifeng Chen
Keyword(s):  
Umbilical Vein ◽  
Average Pore Size ◽  
Three Dimensional ◽  
Cell Encapsulation ◽  
Myocardial Repair ◽  
Average Pore ◽  
Umbilical Vein Endothelial Cells

Alginate is a negative ionic polysaccharide that is found abundantly in nature. Calcium is usually used as a cross-linker for alginate. However, calcium cross-linked alginate is used only forin vitroculture. In the present work, alginate was modified with glycidyl methacrylate (GMA) to produce a thermal polymerizable alginate-GMA (AA-GMA) macromonomer. The molecular structure and methacrylation (%DM) of the macromonomer were determined by1H NMR. After mixing with the correct amount of initiator, the AA-GMA aqueous solution can be polymerized at physiological temperature. The AA-GMA hydrogels exhibited a three-dimensional porous structure with an average pore size ranging from 50 to 200 μm, directly depending on the macromonomer concentration. Biocompatibility of the AA-GMA hydrogel was determined byin vivomuscle injection and cell encapsulation. Muscle injectionin vivoshowed that the AA-GMA solution mixed with initiator could form a hydrogelin situand had a mild inflammatory effect. Human umbilical vein endothelial cells (HUVECs) were encapsulated in the AA-GMA hydrogelsin situat 37°C. Cell viability and proliferation were unaffected by macromonomer concentrations, which suggests that AA-GMA has a potential application in the field of tissue engineering, especially for myocardial repair.

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