scholarly journals Organic Matrix of Enamel and Dentin and Developmental Defects

2021 ◽  
Author(s):  
Eui-Seok Lee ◽  
Puneet Wadhwa ◽  
Min-Keun Kim ◽  
Heng Bo Jiang ◽  
In-Woong Um ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Serum Proteins ◽  
Treatment Plan ◽  
External Disturbance ◽  
Organic Matrix ◽  
Ground Substance ◽  
Developmental Defects ◽  
The Matrix ◽  
Dentin Phosphoprotein ◽  
Dentin Sialoprotein

The anatomical crown of the tooth is covered by enamel and root is covered by cementum. The dentin forms the major part of the tooth. The dentin structure is very similar to that of the bone both physically and chemically which is why many scientists have wondered about using its properties for developing a novel bone graft material. In contrast with hard and brittle enamel dentin is viscoelastic. The organic structure of dentin which is about 35% is composed of mainly type I collagen embedded in mucopolysaccharides ground substance. Approximately half of the non-collagenous composition consists of hyperphosphorylated proteins. The acidic glycoproteins, Gla-proteins, serum proteins, proteoglycans etc. composes the remaining part. The dentin matrix consists of many similar proteins as that of bone like dentin phosphoprotein, dentin sialoprotein etc.. The matrix also consists of many growth factors. Any external disturbance like an infection, trauma, calcium or phosphorous metabolic changes can lead to defective amelogenesis. Mutational changes can lead to defect in dentin. An early diagnosis can result in a satisfactory treatment plan contributing to functional and esthetical compensation.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

Collagen-the Ultrastructural Element of the Bone Matrix

2018 ◽  
Vol 69 (7) ◽  
pp. 1706-1709
Author(s):  
Nicoleta Dumitru ◽  
Andra Cocolos ◽  
Andra Caragheorgheopol ◽  
Constantin Dumitrache ◽  
Ovidiu Gabriel Bratu ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Bone Microarchitecture ◽  
Complex Structure ◽  
Bone Matrix ◽  
Organic Matrix ◽  
Bone Diseases ◽  
Bone Collagen ◽  
Type I ◽  
New Therapeutic Approaches ◽  
And Function

There is an increased interest and more studies highlight the fact that bone strength depends not only on bone tissue quantity, but also on its quality, which is characterized by the geometry and shape of bones, trabecular bone microarchitecture, mineral content, organic matrix and bone turnover. Fibrillar type I collagen is the major organic component of bone matrix, providing form and a stable template for mineralization. The biomedical importance of collagen as a biomaterial for medical and cosmetic purposes and the improvement of the molecular, cellular biology and analytical technologies, led to increasing interest in establishing the structure of this protein and in setting of the relationships between sequence, structure, and function. Bone collagen crosslinking chemistry and its molecular packing structure are considered to be distinct features. This unique post-translational modifications provide to the fibrillar collagen matrices properties such as tensile strength and viscoelasticity. Understanding the complex structure of bone type I collagen as well as the dynamic nature of bone tissues will help to manage new therapeutic approaches to bone diseases.

Matrix-Mineral Relationships-A. Morphologist's Viewpoint

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 922-929 ◽  
Author(s):  
M.U. Nylen
Keyword(s):  
Organic Material ◽  
Crucial Role ◽  
Crystal Surface ◽  
Organic Matrix ◽  
The Other ◽  
Enamel Matrix ◽  
Initial Cell ◽  
Cell Product ◽  
Ultrastructural Morphology ◽  
The Matrix

The literature on the ultrastructural morphology of the enamel matrix and its relationship to the crystals is reviewed. Two morphological entities of the matrix are discussed: One is the so-called stippled material which may be the initial cell product; the other, variously described as fibrillar, lamellar, tubular or helical, is thought by many to play a crucial role in nucleation and orientation of the crystals. A number of observations, however, suggest that the latter structures form secondarily to the crystals and that in reality they represent organic material adsorbed to the crystal surface and maintained as independent structures upon removal of the mineral. The need for additional studies is stressed including systematic studies of interactions between constituents of the organic matrix and the apatite crystals.

scholarly journals Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5531
Author(s):  
Edouard A. T. Davin ◽  
Anne-Lise Cristol ◽  
Arnaud Beaurain ◽  
Philippe Dufrénoy ◽  
Neomy Zaquen
Keyword(s):  
Heat Treatment ◽  
Gray Cast Iron ◽  
Organic Matrix ◽  
Third Body ◽  
Test Program ◽  
Brake Pads ◽  
The Matrix ◽  
Disc Configuration ◽  
Crack Faces ◽  
Reduced Scale

In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage.

scholarly journals CHONDROGENESIS, STUDIED WITH THE ELECTRON MICROSCOPE

1960 ◽  
Vol 8 (3) ◽  
pp. 719-760 ◽  
Author(s):  
Gabriel C. Godman ◽  
Keith R. Porter
Keyword(s):  
Golgi Apparatus ◽  
Ground Substance ◽  
Cell Cortex ◽  
Matrix Space ◽  
Cytoplasmic Inclusions ◽  
Structural Modifications ◽  
Fetal Rat ◽  
The Matrix ◽  
Connective Tissue Matrix ◽  
Tissue Matrix

The role of the cells in the fabrication of a connective tissue matrix, and the structural modifications which accompany cytodifferentiation have been investigated in developing epiphyseal cartilage of fetal rat by means of electron microscopy. Differentiation of the prechondral mesenchymal cells to chondroblasts is marked by the acquisition of an extensive endoplasmic reticulum, enlargement and concentration of the Golgi apparatus, the appearance of membrane-bounded cytoplasmic inclusions, and the formation of specialized foci of increased density in the cell cortex. These modifications are related to the secretion of the cartilage matrix. The matrix of young hyaline cartilage consists of groups of relatively short, straight, banded collagen fibrils of 10 to 20 mµ and a dense granular component embedded in an amorphous ground substance of moderate electron density. It is postulated that the first phase of fibrillogenesis takes place at the cell cortex in dense bands or striae within the ectoplasm subjacent to the cell membrane. These can be resolved into sheaves of "primary" fibrils of about 7 to 10 mµ. They are supposedly shed (by excortication) into the matrix space between the separating chondroblasts, where they may serve as "cores" of the definitive matrix fibrils. The diameter of the fibrils may subsequently increase up to threefold, presumably by incorporation of "soluble" or tropocollagen units from the ground substance. The chondroblast also discharges into the matrix the electrondense amorphous or granular contents of vesicles derived from the Golgi apparatus, and the mixed contents of large vacuoles or blebs bounded by distinctive double membranes. Small vesicles with amorphous homogeneous contents of moderate density are expelled in toto from the chondroblasts. In their subsequent evolution to chondrocytes, both nucleus and cytoplasm of the chondroblasts undergo striking condensation. Those moving toward the osteogenic plate accumulate increasingly large stores of glycogen. In the chondrocyte, the enlarged fused Golgi vesicles with dense contents, massed in the juxtanuclear zone, are the most prominent feature of the cytoplasm. Many of these make their way to the surface to discharge their contents. The hypertrophied chondrocytes of the epiphyseal plate ultimately yield up their entire contents to the matrix.

Cytoskeleton and thyroglobulin expression change during transformation of thyroid epithelium to mesenchyme-like cells

Development ◽  
1988 ◽  
Vol 102 (3) ◽  
pp. 605-622 ◽  
Author(s):  
G. Greenburg ◽  
E.D. Hay
Keyword(s):  
Type I Collagen ◽  
Collagen Gel ◽  
Type I ◽  
Basal Cells ◽  
Collagen Gels ◽  
Expression Change ◽  
Cell Functions ◽  
The Matrix ◽  
3D Matrix ◽  
Mesenchymal Transformation

In considering the mechanism of transformation of epithelium to mesenchyme in the embryo, it is generally assumed that the ability to give rise to fibroblast-like cells is lost as epithelia mature. We reported previously that a definitive embryonic epithelium, that of the anterior lens, gives rise to freely migrating mesenchyme-like cells when suspended in type I collagen matrices. Here, we show that a highly differentiated epithelium that expresses cytokeratin changes to a vimentin cytoskeleton and loses thyroglobulin during epithelial-mesenchymal transformation induced by suspension in collagen gel. Using dispase and collagenase, we isolated adult thyroid follicles devoid of basal lamina and mesenchyme, and we suspended the follicles in 3D collagen gels. Cells bordering the follicle lumen retain epithelial polarity and thyroid phenotype, but basal cell surface organization is soon modified as a result of tissue multilayering and elongation of basal cells into the collagenous matrix. Cytodifferentiation, determined by thyroglobulin immunoreactivity, is lost as the basal epithelial cells move into the matrix after 3–4 days in collagen. By TEM, it can be seen that the elongating cells acquire pseudopodia, filopodia and mesenchyme-like nuclei and RER. Immunofluorescence examination of intermediate filaments showed that freshly isolated follicles and follicles cultured on planar substrata react only with anticytokeratin. However, all of the mesenchyme-like cells express vimentin and they gradually lose cytokeratin. These results suggest that vimentin may be necessary for cell functions associated with migration within a 3D matrix. The mesenchymal cells do not revert to epithelium when grown on planar substrata and the transformation of epithelium to mesenchyme-like cells does not occur within basement membrane gels. The results are relevant to our understanding of the initiation of epithelial-mesenchymal transformation in the embryo and the genetic mechanisms controlling cell shape, polarity and cytoskeletal phenotype.

The Possible Calcification Mechanisms in some Reptilian Egg-shells

1959 ◽  
Vol s3-100 (52) ◽  
pp. 529-538
Author(s):  
K. SIMKISS ◽  
C. TYLER
Keyword(s):  
Toluidine Blue ◽  
Organic Matrix ◽  
Acid Mucopolysaccharide ◽  
Amino Group ◽  
Carboxylate Group ◽  
Shell Matrix ◽  
The Matrix ◽  
Egg Shells ◽  
Egg Shell ◽  
Comparison Of The Results

Studies have been made of the organic matrix of certain reptilian egg-shells. The interaction between egg-shell-matrix and various metal ions has been considered by noting the effect of these ions on the staining of the matrix by toluidine blue. A comparison of the results with those for the hen indicates that the chelating mechanism in the Chelonia is similar to that in the hen, but that that in the Crocodilia is different. It is suggested that in the Crocodilia the acid mucopolysaccharide of the matrix is embedded in, but not combined with, the protein and that its chelating mechanism is carboxylate group to carboxylate group, while in the hen and Chelonia, the acid mucopolysaccharide is combined with the protein and that its chelating mechanism is carboxylate group to amino group.

The Formation and Properties of the Organic Matrix of Reptilian Tooth Enamel

1957 ◽  
Vol s3-98 (43) ◽  
pp. 349-367
Author(s):  
D.F. G. POOLE
Keyword(s):  
Tooth Enamel ◽  
Organic Matrix ◽  
Enamel Formation ◽  
Positive Form ◽  
Form Birefringence ◽  
Parallel Fibres ◽  
The Matrix ◽  
Elementary State ◽  
Simple Step ◽  
Matrix Production

A number of features of enamel formation in the lizard Agama atricollis are described. The behaviour and properties of the ameloblasts indicate that the process of enamel formation is similar to the corresponding process in mammals; the fibrous enamel matrix appears to be formed from outgrowths of the cytoplasm of these cells. Interprismatic material, as it is known in mammals, is not produced, so that reptilian matrix tends to be uniformly fibrous. Nevertheless, the fibres are initially arranged in groups corresponding to the ameloblasts. There is no distinct pre-enamel stage because matrix production is immediately followed by a limited influx of mineral in an elementary state, converting the matrix into an basiphil form. Striae of Retzius may be due to periodic pauses in the normal process of matrix production enabling the ameloblasts to assimilate and secrete mineral. Before the onset of final calcification, the matrix seems to undergo a modification rendering it capable of influencing the size and orientation of mineral crystallites. The organic matrix has a refractive index of 1.57 and has no intrinsic birefringence. However, in suitable liquids the parallel fibres produce a positive form birefringence. If paraffin wax is allowed to crystallize on the matrix, optically negative streaks are formed parallel with the fibres, perhaps as the result of crystal overgrowth. Evidence obtained indicates that this reptilian type of ectodermal enamel is a likely precursor of the mammalian prismatic type. The evolution from one to the other could have been achieved in a comparatively simple step.

scholarly journals N-terminal Dentin Sialoprotein fragment induces type I collagen production and upregulates dentinogenesis marker expression in osteoblasts

2016 ◽  
Vol 6 ◽  
pp. 190-196 ◽  
Author(s):  
Haytham Jaha ◽  
Dina Husein ◽  
Yoshio Ohyama ◽  
Dongliang Xu ◽  
Shigeki Suzuki ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Type I ◽  
Collagen Production ◽  
Marker Expression ◽  
Dentin Sialoprotein

Anisothermic Oxidation of Carbon/Epoxy Laminates

Aerospace ◽  
2006 ◽  
Author(s):  
W. Trabelsi ◽  
V. Bellenger ◽  
E. Ghorbel
Keyword(s):  
Organic Matrix ◽  
Numerical Results ◽  
Oxidation Products ◽  
Matrix Cracking ◽  
Matrix Composites ◽  
Radical Chain ◽  
The Matrix ◽  
Organic Matrix Composites ◽  
C 50 ◽  
Differential Expansion

This work deals with the ageing of a carbon epoxy composite material for aeronautic and supersonic applications. One of the main parameters which governs the durability of this kind of materials is the matrix oxidation, which is limited to surface layers. The long-term behaviour of organic matrix composites includes combined effects of ageing: matrix oxidation occurring at high temperature and matrix cracking due to thermo-mechanical ply stresses induced by differential expansion between matrix and fibers or between the various plies. For some years ENSAM has developed for isothermal conditions a kinetic model of radical chain oxidation coupled with the equation of oxygen diffusion. This model is based on a "close-loop" oxidation mechanistic scheme and gives access to the concentration profile of oxidation products in the sample thickness. In this work we expressed the temperature by a Fourier series and we simulate the oxidative behaviour of samples exposed to the following thermal cycles: -50°C/+180°C, -50°C/+150°C and +50°C/+180°C. The weight loss of the oxidised samples was chosen as indicator of oxidation. Numerical results are compared to experimental ones to check the validity of the model. Good agreement between experimental and numerical results is obtained.

Sign in / Sign up

Export Citation Format

Share Document