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At least 307 records · Page 17Linked to original sources
PubMed1990

A 165 kDa membrane antigen mediating fibronectin-vinculin interaction is involved in murine odontoblast differentiation.

Membrane-mediated matrix-microfilament interactions are involved in odontoblast differentiation. In this study, we analyzed the interactions of vinculin and fibronectin with plasma membrane proteins separated by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis, and then transferred onto polyvinylidene-difluoride (PVDF) paper. Vinculin was found to interact with 58, 63 and 165 kDa plasma membrane proteins. Fibronectin interacted with three high molecular weight (145, 165, and 185 kDa) membrane proteins. Attempts were made to characterize the 165 kDa protein which interacted with vinculin and with fibronectin. The interaction of the 165 kDa protein with fibronectin was not competitively inhibited by synthetic peptides such as GRGDS or GRGDSP, suggesting that the protein was not related to integrins. Antibodies directed against the 165 kDa protein allowed the identification of the precise localization and biological role of this membrane antigen. The data presented in this paper and previous observations indicate that the 165 kDa protein, involved in odontoblast elongation and polarization, mediates a fibronectin-vinculin transmembrane interaction.

Actins↗
PubMed1977

Odontoblast metabolism in rats deficient in vitamin D and calcium I: A histochemical survey.

Different rat diets, deficient in calcium and/or vitamin D, were tested for varying experimental periods to obtain changes in serum calcium values, body weight gain and odontoblast-predentine morphology. One diet, R 25, used during a 14-day period, was found to induce lowered serum calcium values and an increased predentin width in incisor teeth. Rats fed this diet demonstrated an increase in alkaline phosphatase and ATP-splitting enzyme activity in dentinogenically active incisor odontoblasts. No other metabolic changes in these cells were demonstrated by the histochemical methods employed.

Animals↗
PubMed1978

Odontoblast metabolism in rats deficient in vitamin D and calcium. III. Protein synthesis in vitro.

Dentinogenically active rat incisor odontoblasts were dissected out from animals fed a low calcium, vitamin D free diet (R 25). Protein synthesis by these cells was studied by means of short-time incubation in an in vitro system in the presence of the radioactive labeled precursors L-leucine, L-fucose and L-proline. A significantly increased leucine and proline incorporation into the protein synthesized was noted in the cells from rats fed the deficient R 25 diet compared with odontoblasts from rats fed an adequate control diet (R 47). No difference between the two groups was found when fucose was utilized as a precursor. The well known increase in predentin width when feeding a rachitogenic diet may thus be explained by an increase in organic matrix synthesis in addition to the possible negative direct effects of lowered serum Ca content. Prior to this study, the behavior of proline as a precursor in the in vitro system was studied. The possibility of separating leucine-labeled proteins synthesized in the in vitro system by means of SDS-polyacrylamide gel electrophoresis was also shown.

Animals↗
PubMed1981

Colchicine's effects on rat incisor odontoblasts and dentinogenesis.

Colchicine (CLC) in doses of 0.5 and 1.5 mg/kg was administered to 40 female Wistar rats in two equal groups. The animals were sacrificed after 5 h, 24 h, 3 d and 7 d, and the effects of CLC on pulp, odontoblasts and dentin in the continuously growing incisors were studied. With the lowest dose a few arrested mitoses were observed in the germinative part of the pulp after 5 and 24 h. With the highest dose an increasing number of mitoses were observed in the germinative part of the pulp after 5 and 24 h. More incisally the odontoblasts were pale, swollen and granulated after 5 h, and necrotic and disintegrated after 24 h. After 3 and 7 d dentinal derangements, consisting of moderately and severely irregular dentin, osteodentin and a niche-like defect in the labial dentin, were seen. Labially one or two incremental lines traversed the dentin from the apical to the incisal part of the incisors.

Animals↗
PubMed1989

Morphological evidence of the formation of intracellular collagen fibrils in the embryonic mouse molar odontoblasts induced by colchicine administration.

The effects of colchicine on collagen formation were examined ultrastructurally using secretory odontoblasts in mouse molar tooth germs isografted to the spleen for 1 week. Colchicine in concentrations of 0.025 or 0.05 mg/0.1 ml was injected intravenously 12-24 h prior to harvesting. Colchicine induced the disruption of the Golgi apparatus and caused the accumulation of various types of Golgi-associated vacuoles containing collagenous fibrillar structures. Many vacuoles containing fine particles, nonstriated parallel filaments, banding patterns with a periodicity of approximately 63-nm intervals, and occasionally segment-long-spacing-like assemblies were aggregated in the cytoplasm during the experimental period. These morphological changes in vacuole contents may reflect the initial steps for polymerization of the intracellular collagen fibrils. The majority of the aggregated vacuoles were degraded by fusion with lysosomes but banded filamentous material in some vacuoles appeared to polymerize into the collagen fibrils with native structures. These results suggested that in unsecreted vacuoles accumulated in the odontoblasts as a result of colchicine administration the polymerization of collagen fibrils with native structures can occur.

Animals↗
PubMed1979

The extent of the odontoblast process in human dentin.

Impacted human third molar teeth were examined, both with the light and electron microscope, to determine the extent of the odontoblast process. The odontoblast process was found to be limited to the inner third of coronal dentin and inner half of mid-root dentin.

Adult↗
PubMed1980

Dentinal response against carious invasion: localization of antibodies in odontoblastic body and process.

The pulpal origin of dentinal immunoglobulins was demonstrated by means of immunohistological methods. Immunoglobulins were located both in the cytoplasm of odontoblasts in pulp and at odontoblastic processes in dentin. Positive reactivity of the immunoglobulins to antigens was confirmed using peroxidase-immunized rabbits. IgG, IgA, IgM, C3, and C4 were observed on some invasive bacteria in human carious dentin.

Animals↗
PubMed1988

1H and 13C NMR studies of the interaction of eugenol, phenol, and triethyleneglycol dimethacrylate with phospholipid liposomes as a model system for odontoblast membranes.

To clarify the mechanism of the interaction of eugenol with odontoblast membranes compared with that of phenol and triethyleneglycol dimethacrylate (TEGDMA), we employed dipalmitoylphosphatidylcholine (DPPC) liposomes as a model system for odontoblast membranes. 1H and 13C nuclear magnetic resonance spectroscopy (NMR) was used as the spectroscopic approach in the study of this interaction. No signals of 1H and 13C due to eugenol in the DPPC/eugenol liposomes were observed, indicating that the mobility of eugenol was strongly disturbed by DPPC and that eugenol did not diffuse from the liposomes once it was incorporated. The change in chemical shifts due to phenol between the free state and the DPPC/phenol liposomes was not found, indicating that phenol resides in the aqueous phase or near the surfaces of liposomes, its interaction being markedly weaker than that of eugenol. The signals due to TEGDMA in the DPPC/TEGDMA liposomes were split into two peaks: a lower-field peak (free TEGDMA) and a higher-field one (membrane-bound TEGDMA). TEGDMA with ethyleneglycol groups seemed to be activated on the liposomes as a surfactant-like agent.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Odontoblast function seen as the response of dentinal tissue to dental caries.

Microbes are responsible for the initiation and maintaining of carious processes. They have an efficient machinery for dissolving crystalline hydroxyapatite. When initiating carious processes, microbial acid formation determines the rate of the process in enamel. When the process reaches dentin, the micro-environment changes. Dential fluid in dentin tubules is the liquid where dissolving products of apatites are destroyed. Inorganic composition of dentinal fluid, however, is not altered much during the carious process, indicating that a functional secretory domain is working to pump the dissolved calcium and phosphate ions out of the fluid. Activation of odontoblast alkaline phosphatase and dentin latent collagenases is the known cellular event during the carious process in dentin. Because the caries lesion is by definition undermining, this suggests that, in this degradation process, the extracellular compartment, crystalline hydroxyapatite is dissolved by microbial acids, and a mixture of proteinases degrades the organic matrix. The degradation products of collagen and other matrix components in dentinal fluid must be transported either through the caries lesion in the enamel to saliva or through the odontoblast to the pulp (active transport). This facilitates further processing of the degradation products intracellularly during the passage through the cell.

Alkaline Phosphatase↗
PubMed1978

Ultrastructural localization of alkaline phosphatases in rat incisor odontoblasts.

The localization of alkaline phosphatases in dentinogenically active rat incisor odontoblasts was studied by means of subcellular fractionation and electron microscopical histochemistry. Subcellular fractionation revealed the predominant phosphatase activity to be present in the microsome fraction and to a lesser extent in the mitochondrial fraction. Adenosine triphosphate degrading enzyme activity was determined in the presence or absence of (+/-)-6(m-bromophenyl)-5, 6-dihydroimidazo(le) (2,1-b) thiazole oxalate (R 8231). Before the histochemical study, the effects on phosphatase activities by aldehyde fixation were studied by biochemical assay. A method of fixation for optimal preservation of phosphatase activity is presented. Phosphatase electron microscopic histochemistry was performed by using ATP as a substrate and with or without addition of the inhibitor R 82319 Precipitates were seen in the membranes of vesicles present in the odontoblast process and the Golgi region. When there were signs of insufficient fixation, precipitates were also seen in the outer membranes of mitochondria. No phosphatase activity was seen in the cell membrane. ATP degrading enzyme activities mediated by nonspecific alkaline phosphatase (APase) and Ca2+ -adenosine triphosphatase thus have the same morphological localization. This close association is consistent with earlier biochemical studies.

Adenosine Triphosphatases↗
PubMed1989

Immunofluorescent localization of myosin, alpha-actinin and tropomyosin in odontoblast microfilament bundles of the rat incisor.

The localization of alpha-actinin, tropomyosin, myosin and actin in odontoblasts was examined by fluorescence microscopy using well characterized antibodies and rhodamine-phalloidin. All the reagents labeled the distal end of the cell body in the form of an oval ring with a preferential axis along the tooth axis. This ring was often interrupted. In conventional electron microscopy, microfilament bundles with periodical dense spots were running along the tooth axis at the level of the distal end of the cell body. The periodicity was about 0.6-1.0 microns. It may be possible that this dynamic structure functions to keep odontoblasts in a layer by contracting in an isometric form.

Actin Cytoskeleton↗
PubMed2000

Effects of hard tissue-related hormones on the intracellular calcium ion of the rat odontoblasts.

We examined the effects of PTH, calcitonin (CT) and parotin subunit on the intracellular Ca2+ of odontoblasts using a chelate reagent, FURA2-AM. Rat CT (rCT), at a final concentration of 0.01 microM, induced a gradual lowering of Ca2+, and addition of ATP, in the presence of CT, resulted in a partial and short-lasting recovery of Ca2+. At higher concentrations, it caused a rapid decrease of Ca2+. CTs of other animal species showed similar effects. Human PTH (hPTH) added at concentrations of 0.01, 0.1 and 1 microM, caused no significant changes in intracellular Ca2+. Parotin subunit caused a rapid lowering of Ca2+ which was seen already at 0.01 microM. rCT added after treatment with hPTH caused an immediate decrease of Ca2+ to zero level, showing that CT action was enhanced by pretreatment with hPTH. This enhancement was also confirmed by addition of hPTH after rCT, where at 1 microM, it caused further acute decrease in Ca2+. After intracellular Ca2+ was lowered by CT pretreatment, parotin, at 0.1 microM, induced a further but gradual decrease of Ca2+. The present results, together with our previous study indicating that hPTH increased cAMP production and that CT inhibited the PTH action, made it clear that all the hormones affect odontoblasts, and that CT and parotin act via Ca-related signal transduction system, while PTH acts via cAMP-PKA-related cascade. Possible crosstalk of both systems was also suggested.

Adenosine Triphosphate↗
PubMed1998

A histological study of the organic elements in the human enamel focusing on the extent of the odontoblast process.

Topographic and tomographic studies were conducted on the organic elements occluded in the enamel of premolars removed from young orthodontic patients by using light (transmitted) microscopy, confocal scanning laser microscopy (CLSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) on ultrathin sections and freeze-etching replicas, and energy dispersive spectroscopy (EDS) X-ray microscope (EDX) analysis. The present fine structure study aimed in particular to determine the fine structure of the enamel spindle and the extent of the odontoblast process. Organic elements in the ground-sectioned enamel corresponding to simple projections and enamel rods/spindles, enamel tufts and lamellae were identified by conventional light microscopy and subsequently examined by CLSM. Both light microscopy and CLSM indicated that a number of enamel spindles were measured about 50 microns in length, some 4-7 microns in thickness and were mostly confined to the cuspal summits and conformed to previous descriptions. SEM examination revealed some simple projections extending from the dentine into the enamel as well as clearly identifiable enamel spindles; the enamel spindles were structures intervening enamel prisms and showing morphological complexity by branching and convergence of the distal endings of the invading organic structure from dentinal tubules. EDX-analysis revealed that enamel tufts, lamellae, and spindles contained less phosphorus and calcium elements than enamel prisms. The enamel spindles had a higher content than tufts or lamellae, but this may be the result of contamination from surrounding enamel. Both conventional ultrathin-section and freeze-etching replica TEM evaluation of the dentino-enamel boundaries in particular suggested that simple projections and enamel rods/spindles were extensions of the odontoblast processes trapped in the enamel during early amelogenesis. In contrast, both SEM and TEM observations failed to identify dentinal tubule, peritubular (intratubular) dentine, membranous structures or lamina limitans surrounding the enamel spindles and simple projections occluded in the human enamel.

Adolescent↗
PubMed1995

Dentin mineralization and the role of odontoblasts in calcium transport.

Dentin is formed by two simultaneous processes, in which the odontoblasts are instrumental--the formation of the collagenous matrix, and mineral crystal formation in this matrix. This pattern of formation is similar to that of bone, another mineralized connective tissue. Dentin and bone also have chemical compositions which are similar but with distinct differences. It is of fundamental importance to understand how the ions constituting the inorganic phase are transported from the circulation to the site of mineral formation and how this transport is regulated. For dentinogenesis, calcium is essentially the only ion for which data are available. Recent evidence suggests that a major portion of the Ca2+ ions are transported by a transcellular route, thus being under cellular control. The cells maintain a delicate Ca2+ ion balance by the concerted action of transmembraneous transport mechanisms, including Ca-ATPase, Na+/Ca2+ exchangers and calcium channels, and of intracellular Ca(2+)-binding proteins. The net effect of this is a maintenance of a submicromolar intracellular Ca2+ activity, and an extracellular accumulation of Ca2+ ions in predentin, at the mineralization front. Predentin can be regarded as a zone of formation and maturation of the scaffolding collagen web of the dentin organic matrix. In addition to collagen, it contains little but proteoglycan. Simultaneous with mineral formation, additional non-collagenous macromolecules are added to the extracellular matrix of dentin, these presumably being transported within the odontoblast process. Among these are highly phosphorylated dentin phosphoprotein (phosphophoryn) and another pool of proteoglycan.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1998

Odontoblast commitment and differentiation.

Histological and cytological organization confer specificity to the odontoblasts. These postmitotic, neural crest derived, polarized cells are aligned in a single layer at the periphery of the dental pulp and secrete the organic components of predentin-dentin. The developmental history of these cells demands a cascade of epigenetic signalling events comprising the acquisition of odontogenic potential by neural crest cells, their patterning in the developing jaws, the initiation of odontogenesis through interaction with the oral epithelium, commitment, and tooth-specific spatial distribution of competent preodontoblasts able to overtly differentiate. Recent experimental investigations are critically summarized, many open questions are stressed, and current hypotheses concerning the control of terminal odontoblast differentiation are outlined.

Animals↗
PubMed1998

Immunohistochemistry and in situ hybridization investigation of transforming growth factor-beta: during odontoblast and ameloblast differentiation.

OBJECTIVE: The purpose of this study was to investigate the expression of transforming growth factor-beta, TGF-beta 1 during odontoblast and ameloblast differentiation. METHODS: The analysis was made on 5-micron serial sections of the glutaraldehyde-fixed and paraffin-embedded mandibular first and second molars of a neonatal mouse. A specific and affinity-purified antibody to TGF-beta 1 and a digoxigenin-labeled cRNA probe were used. RESULTS: The results showed that the TGF-beta 1 was expressed in a spatial and temporal pattern in dental tissues. The immunoreactivity of dental tissues for TGF-beta 1 was consistent with the expression of TGF-beta 1 mRNA revealed by in situ hybridization before dentin matrix formation. The TGF-beta 1 was evenly expressed in dental papilla and inner enamel epithelium. The expression of TGF-beta 1 was increased in the layer of odontoblasts and ameloblasts and in the stratum intermedium with the formation of dentin matrix, where the staining was also observed. CONCLUSIONS: These findings suggest that TGF-beta 1 may have an important role in extracellular matrix formation and cytodifferentation.

Ameloblasts↗
PubMed1999

Spatial and temporal activity of the dentin sialophosphoprotein gene promoter: differential regulation in odontoblasts and ameloblasts.

Dentin sialoprotein and dentin phosphoprotein are non-collagenous proteins that are cleavage products of dentin sialophosphoprotein (DSPP). Although these two protein products are believed to have a crucial role in the process of tooth mineralization, their precise biological functions and the molecular mechanisms of gene regulation are not clearly understood. To understand such functions, we have developed a transgenic mouse model expressing a reporter gene (lacZ) under the control of approximately 6 kb upstream sequences of Dspp. The transgenic fusion protein was designed to reside within the cells to facilitate the precise identification of cell type and developmental stages at which the Dspp-lacZ gene is expressed. The results presented in this report demonstrate: (a) the 6 kb upstream sequences of Dspp have the necessary regulatory elements to direct the tissue specific expression of the transgene similar to endogenous Dspp, (b) both odontoblasts and ameloblasts exhibit transgene expression in a differentiation dependent manner, and (c) a differential regulation of the transgene in odontoblasts and ameloblasts occurs during tooth development and mineralization.

Ameloblasts↗
PubMed1975

The dentinal tubule and odontoblast process in the cat.

The odontoblast process and dentinal tubule of the cat have been examined after vascular perfusion of aldehydes for periods of 20-60 minutes. The odontoblast process is apparently confined to the inner half of a dentinal tubule. Its structure consists of microtubules, microfilaments and a variable population of vesicles, all surrounded by a plasma membrane. The apparent limited peripheral extent of the process is perhaps an artefact due to incomplete penetration of the fixatives.

Aldehydes↗