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At least 109 records · Page 6Linked to original sources
PubMed1992

Actions of parathyroid hormone on cultured human dental pulp cells.

The responsiveness of human dental pulp (HDP) cells to parathyroid hormone (PTH) was investigated by measuring their cyclic AMP (cAMP) content, DNA synthesis, alkaline phosphatase activity, collagen synthesis, and glycosaminoglycan (GAG) synthesis. PTH dose-dependently increased the intracellular cAMP 1 min after the addition of PTH. Confluent HDP cells on day 14 expressed a high level of cAMP production after addition of 3 units/ml PTH. The hormone did not affect DNA synthesis by HDP cells. Alkaline phosphatase activity was suppressed by PTH to 81% of control (p < 0.01), and addition of dibutyryl cAMP to the medium mimicked the effect of PTH (79% of control, p < 0.01). The hormone inhibited collagen synthesis (15% decrease of [3H] proline incorporation, p < 0.01), and stimulated non-collagen protein synthesis (10% increase, p < 0.05). The increase of non-collagen protein by PTH was in accordance with the enhancement of GAG synthesis (17% increase of [35S]sulfate incorporation, p < 0.01). Dibutyryl cAMP caused further increase of GAG synthesis, to 155% of control (p < 0.01). Observations of the radiolabeled proteins on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis after metabolic labeling with [14C]proline and [35S]sulfate revealed a similar tendency to the quantitative determinations in which PTH inhibited collagen synthesis and stimulated GAG synthesis. These findings suggest that HDP cells have some osteoblastic characteristics in terms of PTH responsiveness, and that this culture system is a useful model for studies of human dental pulp.

Adolescent↗
PubMed2001

Dental pulp cells produce neurotrophic factors, interact with trigeminal neurons in vitro, and rescue motoneurons after spinal cord injury.

Interactions between ingrowing nerve fibers and their target tissues form the basis for functional connectivity with the central nervous system. Studies of the developing dental pulp innervation by nerve fibers from the trigeminal ganglion is an excellent example of nerve-target tissue interactions and will allow specific questions regarding development of the dental pulp nerve system to be addressed. Dental pulp cells (DPC) produce an array of neurotrophic factors during development, suggesting that these proteins might be involved in supporting trigeminal nerve fibers that innervate the dental pulp. We have established an in vitro culture system to study the interactions between the dental pulp cells and trigeminal neurons. We show that dental pulp cells produce several neurotrophic factors in culture. When DPC are cocultured with trigeminal neurons, they promote survival and a specific and elaborate neurite outgrowth pattern from trigeminal neurons, whereas skin fibroblasts do not provide a similar support. In addition, we show that dental pulp tissue becomes innervated when transplanted ectopically into the anterior chamber of the eye in rats, and upregulates the catecholaminergic nerve fiber density of the irises. Interestingly, grafting the dental pulp tissue into hemisected spinal cord increases the number of surviving motoneurons, indicating a functional bioactivity of the dental pulp-derived neurotrophic factors in vivo by rescuing motoneurons. Based on these findings, we propose that dental pulp-derived neurotrophic factors play an important role in orchestrating the dental pulp innervation.

Animals↗
PubMed1991

Histopathologic effects of electric dosage in iontophoresis on dental pulp.

It is well recognized that dental pulp is very sensitive to electricity. However, the extent of damage and the repair capacity of pulp tissue after the electrical excitation of iontophoresis remains to be determined. Electrical current was applied to the simian teeth via cavities on the buccal or occlusal surfaces. The current strength was set at 0.1 mA-0.4 mA. The application duration was either 1 minute or 3 minutes. The total dose of electricity received by the iontophoresed teeth varied from 0.1 mA-minute to 1.2 mA-minutes. The pulps were microscopically examined at 4, 8, and 12 weeks after electrical excitation. All of the teeth were collected and processed using routine histologic methods. The following results were obtained: (1) in the group with 1-minute iontophoresis, the histologic pictures showed no apparent differences among the specimens regardless of the strength of the current applied; (2) in the group with 3-minute iontophoresis, the pulpal response correlated positively with current strength; and (3) with an electrical current of no greater than 0.4 mA and an application period of less than 3 minutes, the pulpal changes were reversible. We conclude that iontophoresis may accelerate the repair process, if the application duration is less than 3 minutes.

Animals↗
PubMed1985

Narrowing of the dental pulp chamber in patients with renal diseases.

Narrowing of the dental pulp chamber was studied radiologically in fifty one patients with renal diseases. Two thirds of the patients were suffering from terminal uremia and were treated either by renal transplantation or with hemodialysis. The remaining patients were nonuremic and were treated with immunosuppressants because of progressive renal disease. There were significantly more patients with narrowing of the dental pulp chamber among the transplant patients than among the other patients. The transplantations included the use of higher doses of corticosteroids than the other treatments. As the median dose of corticosteroids was higher and total plasma steroid clearance was lower in the patients with narrowing of the dental pulp chamber than in the other patients, the amount of this drug received and its pharmacokinetics seemed to be an essential factor in the initiation of narrowing of the dental pulp chamber.

Adolescent↗
PubMed2001

Localization of metallothionein (MT) and expression of MT isoforms induced by cadmium in rat dental pulp.

We investigated the induction of metallothionein (MT) by cadmium (Cd) in the dental pulp of rat incisors. Time-course studies of MT mRNA expression after single Cd injection were observed by Northern-blot analysis. The isoform-specific expressions of MT mRNAs (MT-I, MT-II and MT-III) were observed using the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Both MT-I and MT-II mRNA levels increased within 3 h, peaked at 3 h and then decreased. These findings demonstrated that MT-I and MT-II mRNA were rapidly induced by Cd in dental pulp. MT-III mRNA was constitutively expressed in rat dental pulp, but the expression level did not change by Cd treatment. The localization of MT protein in Cd-treated rat dental pulp was determined by immunohistochemical staining using anti-MT antibody against MT-I and MT-II. MT protein was localized in the specific cell type of odontoblasts (secretory odontoblasts and resting odontoblasts). In conclusion, it is likely that stained MT in the immunohistochemical study should be MT-I and/or MT-II. Furthermore, MT-I and/or MT-II in Cd-treated rat dental pulp was localized in odontoblasts, in which accumulation of Cd were reported. The cell-specific synthesis of MT may be associated with its metal storage and detoxification role in dental tissues.

Animals↗
PubMed1994

Effects of 6-hydroxydopamine on noradrenaline metabolism linked to neuronal uptake1 and extraneuronal uptake1 in dental pulp in vitro.

The study was undertaken to determine the relative roles of neuronal and extraneuronal uptake1 in the metabolism of 3H-noradrenaline in human dental pulp. Rabbit dental pulp was used as a reference since it was already known that normetanephrine (NMN) formation in this tissue utilised extraneuronal uptake1. Slices of pulp were preincubated in the absence and presence of 6-hydroxydopamine (1.6 mmol/l, for 10 or 20 min at pH 4.5) and subsequently incubated with 3H-noradrenaline (0.18 mumol/l for 30 min at pH 7.4). The principal metabolites formed were normetanephrine in rabbit pulp and deaminated catechols (dihydroxymandelic acid and dihydroxyphenylglycol) in human pulp. In both tissues 6-hydroxydopamine strongly inhibited formation of the deaminated catechols, but was without effect on normetanephrine formation. It is concluded that: i) in vitro 6-hydroxydopamine does not influence the metabolic process which is dependent on extraneuronal uptake1, namely normetanephrine formation in rabbit dental pulp, and ii) the deaminated catechols are largely neuronal in origin in human pulp. Attention is drawn to an unusual feature of the neuronal metabolism in human pulp, namely the appearance of dihydroxymandelic acid as the principal metabolite.

Adult↗
PubMed2005

Neuropeptide release from dental pulp cells by RgpB via proteinase-activated receptor-2 signaling.

Dental pulp inflammation often results from dissemination of periodontitis caused mostly by Porphyromonas gingivalis infection. Calcitonin gene-related peptide and substance P are proinflammatory neuropeptides that increase in inflamed pulp tissue. To study an involvement of the periodontitis pathogen and neuropeptides in pulp inflammation, we investigated human dental pulp cell neuropeptide release by arginine-specific cysteine protease (RgpB), a cysteine proteinase of P. gingivalis, and participating signaling pathways. RgpB induced neuropeptide release from cultured human pulp cells (HPCs) in a proteolytic activity-dependent manner at a range of 12.5-200 nM. HPCs expressed both mRNA and the products of calcitonin gene-related peptide, substance P, and proteinase-activated receptor-2 (PAR-2) that were also found in dental pulp fibroblast-like cells. The PAR-2 agonists, SLIGKV and trypsin, also induced neuropeptide release from HPCs, and HPC PAR-2 gene knockout by transfection of PAR-2 antisense oligonucleotides inhibited significantly the RgpB-elicited neuropeptide release. These results indicated that RgpB-induced neuropeptide release was dependent on PAR-2 activation. The kinase inhibitor profile on the RgpB-neuropeptide release from HPC revealed a new PAR-2 signaling pathway that was mediated by p38 MAPK and activated transcription factor-2 activation, in addition to the PAR-2-p44/42 p38MAPK and -AP-1 pathway. This new RgpB activity suggests a possible link between periodontitis and pulp inflammation, which may be modulated by neuropeptides released in the lesion.

Activating Transcription Factor 2↗
PubMed2006

In vitro chromosome aberration tests using human dental pulp cells to detect the carcinogenic potential of chemical agents.

To examine if human dental pulp cells are useful for assessing the carcinogenic potential of chemical agents, we cultured human dental pulp cells from adults and studied the ability of chemical agents known to be carcinogenic to induce chromosome aberrations in these cells. We confirmed that human dental pulp cells in primary or secondary cultures had the capability of accumulating calcium in vitro as detected by Alizarin red staining and generating dentin-like tissue in immunocompromised mice. These phenotypes were maintained even in cells at seven passages. Next, we examined if chromosome aberrations were induced by exposure of human dental pulp cells (designated here as D824 cells) at seven to nine passages to chemical agents with carcinogenic activity. Statistically significant increases in the frequencies of chromosome aberrations were induced in D824 cells treated with a direct-acting carcinogen, mitomycin C, for 3 h. Chromosome aberrations were also induced at statistically significant levels in D824 cells treated with an indirect-acting carcinogen, cyclophosphamide, for 2 h in the presence of exogenous metabolic activation with rat liver postmitochondrial supernatant. Cyclophosphamide failed to induce chromosome aberrations in the absence of exogenous metabolic activation. Although the reliability of chromosome aberration tests using human dental pulp cells remains to be validated by studying the ability of various other chemical agents with or without carcinogenic activity to induce chromosome aberrations, this chromosome aberration test system may be useful for carcinogenic risk assessment in the target cells.

Adolescent↗
PubMed1995

Absence of parasympathetic vasodilatation in cat dental pulp.

The existence and nature of parasympathetic nerve fibers in the dental pulp have long been a subject for discussion; indeed, vasodilator responses mediated by such nerve fibers have yet to be conclusively demonstrated in the dental pulp. This study was designed to determine whether parasympathetic vasodilator mechanisms do or do not exist in the cat dental pulp. Dynamic changes in pulpal blood flow (PBF), with mandibular lip blood flow (LBF) recorded as a control, were investigated in cat mandibular canine teeth by means of laser Doppler velocimetry. Peripheral trigeminal afferents (see below) were stimulated electrically to confirm that somato-parasympathetic reflex vasodilatation could be induced. The peripheral cut ends of the facial and glossopharyngeal nerve roots, which have been reported to contain parasympathetic nerve fibers to the oral tissues, were then stimulated intracranially. Electrical stimulation of trigeminal afferents (in the infraorbital nerve or the maxillary buccal gingiva) caused no change in PBF but did increase ipsilateral LBF. Neither facial nor glossopharyngeal nerve root stimulation caused a PBF increase, though both elicited increases in ipsilateral LBF. The vasodilator responses in the lip were sensitive to ganglion blockade (with hexamethonium), indicating vasodilatation via activation of parasympathetic vasodilator fibers. In contrast, intracranial stimulation of the trigeminal nerve root induced increases in both PBF and LBF which were reduced by pre-treatment with tripelennamine, indicating antidromic vasodilatation via the trigeminal sensory nerve. These results suggest that a parasympathetic vasodilator mechanism is not present in feline dental pulp.

Animals↗
PubMed1990

[Studies on pyruvate kinase from pig dental pulp and brain].

Most of the enzymes involved in glycolysis are readily reversible and are also active in gluconeogenesis. However, three reaction steps are irreversible, i.e., those catalyzed by hexokinase, phosphofructokinase, and pyruvate kinase; for in each of these reactions there occurs a large negative free-energy change, and these are reactions thus bypassed by alternate enzyme-catalyzed reactions. Pyruvate kinase (EC 2.7.1.40, PK) plays an important role in controlling glycolysis and gluconeogenesis. To clarify the characteristics of glycolysis in dental pulp, we examined the enzymatic properties of pyruvate kinase from pig dental pulp and compared them with those of the enzyme from pig brain. 1) Pyruvate kinase from dental pulp and brain were purified by use of ammonium sulphate fractionation, phosphocellulose colum chromatography, and isoelectric focusing. The prepared enzymes showed a single protein band on SDS polyacrylamide gel electrophoresis. 2) The subunit molecular weight of dental pulp and brain enzymes was determined to be 63,000 and 59,000, respectively. 3) Substrate inhibition of dental pulp and brain enzymes by phosphoenolpyruvate was not observed, and the relationship between reaction velocity and substrate concentration at pH 7.2 was explained by the Michaelis-Menten equation. Fructose-1,6-diphosphate had no observable effect on either enzyme. 4) Effect of amino acids on dental pulp and brain enzyme activity were examined, and no significant relationship was observed between the side chain structure of amino acids and their potency in inhibiting dental pulp and brain enzyme activity. Glutamic and aspartic acids markedly inhibited dental pulp and brain enzymes at pH 7.2. 5) Oxalate showed inhibitory activity against dental pulp and brain enzymes, and the Ki value was determined to be 50 microM and 80 microM, respectively. The inhibition of dental pulp and brain enzyme activity by oxalate was competitive with respect to phosphoenolpyruvate. 6) Both dental pulp and brain enzymes were clearly inhibited by malate at concentrations higher than 1.0 mM: 50% and 100% inhibition occurred at 2.2-2.3 mM and 3.0 mM malate, respectively.

Animals↗
PubMed2006

An ultrastructural study on indirect trauma of dental pulp caused by maxillofacial impact injury in dogs.

BACKGROUND: Indirect injuries of adjacent tissues and organs usually accompany maxillofacial impact injuries. However, studies on indirect dental pulp injury are rare. This study was designed to determine the characteristics of indirect dental pulp injury caused by impact injury of mandible in dogs. METHODS: Eighteen dogs were divided equally into six groups with random allocation. Right mandible of each dog was impacted but teeth were not injured directly. Then, the animals were killed at appointed time points and ultrastructural changes in dental pulp of assigned teeth of each dog were investigated with transmission electron microscope. RESULTS: Dental pulp of the fourth premolar of right mandible was injured very severely, but irreversible necrosis did not occur in the end. Dental pulp of the second premolar of right mandible was injured less severely and reversibly. Dental pulp of the second premolar of left mandible was injured mildly and temporarily. CONCLUSION: In the indirect injury of dental pulp caused by maxillofacial impact injury, the injured area is relatively extensive. The effect of the trauma decreases progressively and sharply as the distance to the impact site increases. Ultrastructural changes in the damaged nerves take place early.

Animals↗
PubMed1998

The role of integrin beta 1 in human dental pulp cell adhesion on laminin and fibronectin.

OBJECTIVE: This study is to identify the expression of integrin beta 1 in human dental pulp cells and the role of integrin beta 1 in pulp cell adhesion on extracellular matrix protein laminin and fibronectin. STUDY DESIGN: Immunoblot detection of integrin beta 1 in human pulp cells was with the use of monoclonal anti-beta 1 antibody. Dental pulp cell adhesion assay on extracellular matrix protein laminin and fibronectin and blocking cell adhesion was performed with monoclonal anti-beta 1 antibody. RESULT: Integrin beta 1 was identified in human dental pulp cells. Pulp cells adhered and spread on both laminin and fibronectin. Monoclonal anti-beta 1 antibody inhibited human dental pulp cells adhesion on laminin but not on fibronectin. CONCLUSIONS: Integrin beta 1 was expressed on human dental pulp cells and mediated cell adhesion on laminin. Human dental pulp cells also adhered on fibronectin but the adhesion was not regulated by beta 1 integrin.

Antibodies, Monoclonal↗
PubMed2001

Alteration in the expression of heat shock protein (Hsp) 25-immunoreactivity in the dental pulp of rat molars following tooth replantation.

The regeneration process of dental pulp following tooth replantation in rat molars was investigated by immunocytochemistry for heat shock protein (Hsp) 25 and protein gene product 9.5 (PGP 9.5). In control teeth at postnatal 4 weeks, the odontoblasts showed intense Hsp 25-immunoreactivity in the coronal dental pulp, but little or no immunoreactivity in the root and floor pulp. In contrast, the Hsp 25-negative odontoblasts in the latter areas displayed immunoreactivity for PGP 9.5. Tooth replantation caused loss of Hsp 25- and PGP 9.5-immunoreactions in the dental pulp during postoperative days 1-3. At postoperative day 5, plump cells with clear nucleoli and several fine processes--presumably newly differentiated odontoblasts--at the pulp-dentin border became immunopositive for Hsp 25. These data suggest that the expression of Hsp 25- and PGP 9.5-immunoreactivity reflects the status of differentiation of the odontoblasts. Furthermore, some pulpal nerve fibers as well as the Schwann cells in the dental pulp, ordinarily negative in Hsp 25-immunoreaction, acquired their immunoreactivity by postoperative day 5, but lost it thereafter, suggesting the involvement of Hsp 25 in the regeneration of pulpal nerve fibers. In the case of bone-like tissue formation in the pulp space, on the other hand, no Hsp 25-immunoreactive odontoblasts were recognized in the pulp-dentin border. Thus, the alignment of Hsp 25-immunopositive odontoblasts along the pulp-dentin border indicates a decisive factor for inducing the reparative dentin formation after tooth replantation.

Animals↗