RESUMEN
BACKGROUND AND OBJECTIVE: Short-chain fatty acids, such as butyric acid and propionic acid, are metabolic by-products generated by periodontal microflora such as Porphyromonas gingivalis, and contribute to the pathogenesis of periodontitis. However, the effects of butyrate on the biological activities of gingival fibroblasts (GFs) are not well elucidated. MATERIAL AND METHODS: Human GFs were exposed to various concentrations of butyrate (0.5-16 mm) for 24 h. Viable cells that excluded trypan blue were counted. Cell cycle distribution of GFs was analyzed by propidium iodide-staining flow cytometry. Cellular reactive oxygen species (ROS) production was measured by flow cytometry using 2',7'-dichlorofluorescein (DCF). Total RNA and protein lysates were isolated and subjected to RT-PCR using specific primers or to western blotting using specific antibodies, respectively. RESULTS: Butyrate inhibited the growth of GFs, as indicated by a decrease in the number of viable cells. This event was associated with an induction of G0/G1 and G2/M cell cycle arrest by butyrate (4-16 mm) in GFs. However, no marked apoptosis of GFs was noted in this experimental condition. Butyrate (> 2 mm) inhibited the expression of cdc2, cdc25C and cyclinB1 mRNAs and reduced the levels of Cdc2, Cdc25C and cyclinB1 proteins in GFs, as determined using RT-PCR and western blotting, respectively. This toxic effect of butyrate was associated with the production of ROS. CONCLUSION: These results suggest that butyrate generated by periodontal pathogens may be involved in the pathogenesis of periodontal diseases via the induction of ROS production and the impairment of cell growth, cell cycle progression and expression of cell cycle-related genes in GFs. These events are important in the initiation and prolongation of inflammatory processes in periodontal diseases.
Asunto(s)
Butiratos/farmacología , Fibroblastos/efectos de los fármacos , Encía/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Apoptosis/efectos de los fármacos , Butiratos/toxicidad , Proteína Quinasa CDC2 , Técnicas de Cultivo de Célula , Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Forma de la Célula/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Colorantes , Ciclina B/efectos de los fármacos , Ciclina B1/efectos de los fármacos , Quinasas Ciclina-Dependientes , Fibroblastos/citología , Citometría de Flujo , Fluoresceína-5-Isotiocianato , Fluoresceínas , Colorantes Fluorescentes , Puntos de Control de la Fase G1 del Ciclo Celular/efectos de los fármacos , Puntos de Control de la Fase G2 del Ciclo Celular/efectos de los fármacos , Encía/citología , Humanos , Puntos de Control de la Fase M del Ciclo Celular/efectos de los fármacos , Propidio , Fase de Descanso del Ciclo Celular/efectos de los fármacos , Fosfatasas cdc25/efectos de los fármacosRESUMEN
Transforming growth factor-beta (TGF-beta) is important in regulating the repair and regeneration of damaged dental pulp. For further elucidating the roles of different isoforms of TGF-beta in the healing and inflammatory processes of human dental pulp, we found that TGF-beta1, TGF-beta2 and TGF-beta3 inhibited the growth of two human dental pulp cell strains in vitro by 19-29, 18-25 and 23-26%, respectively, at a concentration of 0.5 ng/ml. TGF-beta also differentially stimulated the collagen synthesis of pulp cells. Collagen synthesis increased by 1 ng/ml of TGF-beta1 and TGF-beta2 by 42 and 51%, respectively. TGF-beta3 (0.1-1 ng/ml) lacked of stimulatory effect on collagen synthesis of pulp cells. Pulp cells have the intrinsic capacity to contract collagen lattice, leading to decreasing of lattice diameter. An 8 h exposure to TGF-beta1 and TGF-beta2 enhanced the pulp cell-populated collagen lattice contraction at concentrations ranging from 0.2 to 3 ng/ml. At similar concentrations, TGF-beta3 lacked of this stimulatory effect. When collagen lattice were detached after 24 h of exposure, TGF-beta1 and TGF-beta2 (0.6-3 ng/ml) induced the pulp cells-populated collagen lattice contraction within 4-8h of gel detachment. These results indicate that TGF-beta-induced collagen lattice contraction is a late cellular event. These in vitro results indicate that effects of TGF-beta isoforms on the growth, collagen synthesis and collagen lattice contraction of pulp cells may play crucial roles in the pathobiological processes of dental pulp.
Asunto(s)
Colágeno/biosíntesis , Pulpa Dental/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Factor de Crecimiento Transformador beta/farmacología , División Celular/efectos de los fármacos , Tamaño de la Célula/efectos de los fármacos , Células Cultivadas , Pulpa Dental/citología , Pulpa Dental/metabolismo , Relación Dosis-Respuesta a Droga , Fibroblastos/metabolismo , Humanos , Isoformas de Proteínas/farmacología , Proteínas Recombinantes/farmacología , Factor de Crecimiento Transformador beta1 , Factor de Crecimiento Transformador beta2 , Factor de Crecimiento Transformador beta3RESUMEN
Root surface demineralization is widely used as an adjunct to periodontal treatment. To clarify the influence of citric acid root conditioning on periodontal wound healing, the effects of citric acid and associated extracellular acidosis on the viability (MTT assay), attachment and protein synthesis ([3H]-proline incorporation into trichloroacetic acid-precipitated proteins) of human gingival fibroblasts (GF) were investigated. A concentration of 47.6 mmol/L of citric acid (pH 2.3) in water led to total cell death within three minutes of incubation. Media containing 23.8 mmol/L and 47.6 mmol/L of citric acid exerted strong cytotoxicity (47 to 90 per cent of cell death) and inhibited protein synthesis (IC50 = 0.28 per cent) of GF within three hours of incubation. Incubation of cells in a medium containing 11.9 mmol/L of citric acid also suppressed the attachment and spreading of fibroblasts on culture plates and Type I collagen, with 58 per cent and 22 per cent of inhibition, respectively. Culture medium supplemented with 11.9, 23.8 and 47.6 mmol/L of citric acid also led to extracellular acidosis by decreasing the pH value from 7.5 to 6.3, 5.2 and 3.8, respectively. In addition, it was confirmed that the toxic effect of media containing citric acid was due to their acidity rather than the citrate content. Most of the citric acid-induced cell death could be prevented by adjusting the pH value of the culture medium to pH 7.5. Sodium citrate, at a concentration of 47.6 mmol/L, also exerted little cytotoxicity. The results suggested that toxicity of citric acid in specific stages of the healing process must be considered prior to its clinical application. Careful management of citric acid in order to avoid contact with tissue or the development of other demineralizing agents is important in enhancing periodontal wound healing.
Asunto(s)
Quelantes/farmacología , Ácido Cítrico/farmacología , Fibroblastos/efectos de los fármacos , Encía/efectos de los fármacos , Proteínas/efectos de los fármacos , Acidosis/metabolismo , Adhesión Celular/efectos de los fármacos , Muerte Celular , Movimiento Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Precipitación Química , Citratos/farmacología , Colágeno , Colorantes , Medios de Cultivo , Fibroblastos/citología , Fibroblastos/metabolismo , Encía/citología , Encía/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Prolina/metabolismo , Biosíntesis de Proteínas , Proteínas/antagonistas & inhibidores , Radiofármacos , Citrato de Sodio , Sales de Tetrazolio , Tiazoles , Ácido Tricloroacético , Tritio , Cicatrización de HeridasRESUMEN
In Matsuda's 1996 study, 4- to 11-yr.-old children (N = 133) watched two cars running on two parallel tracks on a CRT display and judged whether their durations and distances were equal and, if not, which was larger. In the present paper, the relative contributions of the four critical stimulus attributes (whether temporal starting points, temporal stopping points, spatial starting points, and spatial stopping points were the same or different between two cars) to the production of errors were quantitatively estimated based on the data for rates of errors obtained by Matsuda. The present analyses made it possible not only to understand numerically the findings about qualitative characteristics of the critical attributes described by Matsuda, but also to add more detailed findings about them.