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1.
Neural Netw ; 122: 308-319, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31739269

RESUMEN

High-frequency deep brain stimulation (HF-DBS) of the subthalamic nucleus (STN), globus pallidus interna (GPi) and globus pallidus externa (GPe) are often considered as effective methods for the treatment of Parkinson's disease (PD). However, the stimulation of a single nucleus by HF-DBS can cause specific physical damage, produce side effects and usually consume more electrical energy. Therefore, we use a biophysically-based model of basal ganglia-thalamic circuits to explore more effective stimulation patterns to reduce adverse effects and save energy. In this paper, we computationally investigate the combined DBS of two nuclei with the phase deviation between two stimulation waveforms (CDBS). Three different stimulation combination strategies are proposed, i.e., STN and GPe CDBS (SED), STN and GPi CDBS (SID), as well as GPi and GPe CDBS (GGD). Resultantly, it is found that anti-phase CDBS is more effective in improving parkinsonian dynamical properties, including desynchronization of neurons and the recovery of the thalamus relay ability. Detailed simulation investigation shows that anti-phase SED and GGD are superior to SID. Besides, the energy consumption can be largely reduced by SED and GGD (72.5% and 65.5%), compared to HF-DBS. These results provide new insights into the optimal stimulation parameter and target choice of PD, which may be helpful for the clinical practice.


Asunto(s)
Estimulación Encefálica Profunda/métodos , Globo Pálido/fisiopatología , Modelos Neurológicos , Enfermedad de Parkinson/terapia , Núcleo Subtalámico/fisiopatología , Tálamo/fisiopatología , Biofisica , Humanos , Neuronas/fisiología , Enfermedad de Parkinson/fisiopatología
2.
Arch Oral Biol ; 56(10): 997-1004, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21411061

RESUMEN

OBJECTIVES: This study aims to evaluate the mineral density, calcium (Ca), and phosphorus (P) weight percent of healthy human enamel of varying human teeth age and enamel layers. METHODS: Twenty human teeth were divided into "young" (18-24 years) and "old" (55 ≤ years) age groups. From each tooth, one enamel slab (approximately 8 mm × 2 mm × 1.5 mm) was obtained. All enamel slabs were embedded and scanned by micro-computed tomography. The scanned slices were reconstructed into a 3D image and regions of interest (ROIs) were defined. Then, the mineral density for each ROI was calculated. The Ca and P weight percent in the outer, middle, and inner enamel layers were quantified by scanning electron microscopy with energy dispersive spectroscopy. Finally, the data were analysed using one-way ANOVA and Student's t-test. RESULTS: In the two age groups, the mineral density, Ca and P weight percent decreased from outer to the inner enamel layer. The mineral density, Ca and P weight percent in the outer enamel layer in the old age group were significantly higher than those in the young age group (P<0.05); however, no age-dependent differences were observed for these properties in the middle and inner enamel layers (P>0.05). CONCLUSIONS: The mineral density, Ca and P weight percent decreased from the outer to the inner enamel layers in the two age groups. In the outer enamel layer, the differences in these properties between the two age groups were significantly different; however, no region-dependent differences were observed in the middle and inner enamel layers.


Asunto(s)
Calcio/análisis , Esmalte Dental/ultraestructura , Minerales/química , Fósforo/análisis , Adolescente , Factores de Edad , Esmalte Dental/química , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Microscopía Electrónica de Rastreo , Persona de Mediana Edad , Tercer Molar/química , Tercer Molar/ultraestructura , Espectrometría por Rayos X , Microtomografía por Rayos X/métodos , Adulto Joven
3.
Arch Oral Biol ; 55(6): 435-40, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20392436

RESUMEN

OBJECTIVE: The aim of the study was to investigate the effect of chemical compounds of Galla chinensis on in vitro the remineralization of enamel surface. METHOD: Bovine enamel blocks with in vitro produced initial lesions were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4x1 min applications with one of four treatments: Group A: 1000 ppm F aq. (as NaF, positive control); Group B: deionized water (DDW, negative control); Group C: 4000 ppm crude aqueous extract of G. chinensis (GCE); Group D: 4000 ppm gallic acid. The enamel specimens were analysed by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray microdiffraction (XRD). RESULTS: The morphology of surface enamel was different in each group. The mineral composition was identified as similar to hydroxylapatite, but the crystallite sizes of enamel in different groups were significantly different. In addition, the Ca/P ratios were significantly lower in GCE group. CONCLUSION: GCE could affect the mineral ions deposit on the surface layer and then modified the remineralization of initial dental caries. The mechanism seems to be different between GCE and gallic acid.


Asunto(s)
Cariostáticos/farmacología , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Extractos Vegetales/farmacología , Remineralización Dental , Animales , Bovinos , Cristalografía por Rayos X , Esmalte Dental/patología , Ácido Gálico/farmacología , Dureza/efectos de los fármacos , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Rastreo , Espectroscopía de Fotoelectrones , Porosidad , Fluoruro de Sodio/farmacología , Propiedades de Superficie , Desmineralización Dental , Agua/farmacología
4.
Am J Dent ; 23(4): 196-200, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21250568

RESUMEN

PURPOSE: To determine whether natural smoking stain could be removed/inhibited effectively by a toothpaste containing 5% d-limonene. For comparison and contrast, the effects of d-limonene on tea stain were also assessed. METHODS: The design was a randomized controlled double-blind trial with parallel groups. Toothpastes were: A: positive control with perlite whitening formulation; B: A+5% d-limonene; C: D + 5% d-limonene; D: negative control. The extrinsic stains were measured using Lobene Stain Index. Following baseline examination, all subjects were randomly assigned to one of the four toothpaste groups and instructed to brush with the assigned products twice daily. Subjects returned to the clinic after 4-week brushing for stain removal assessment, then all extrinsic stains, plaque and supragingival calculus were removed and use of assigned products was continued for another 4 weeks, and the stain scores were repeated for inhibition assessment. RESULTS: A total of 408 subjects, 201 with smoking stains and 207 with tea stains, participated in the trial. 5% d-limonene combined with Perlite whitening formulation significantly reduced stain scores both for smoking stain removal and inhibition (P < 0.05). Furthermore, 5% d-limonene alone (in negative formulation) exhibited an additional advantage for smoking stain inhibition (P < 0.05), but the advantage was not found for long-standing smoking stain removal (P > 0.05). The additional advantage of 5% d-limonene was shown neither for removal nor for inhibition in the tea stain study (P > 0.05). All test products were well tolerated over the study period.


Asunto(s)
Ciclohexenos/uso terapéutico , Fumar/efectos adversos , Terpenos/uso terapéutico , Blanqueadores Dentales/uso terapéutico , Decoloración de Dientes/terapia , Pastas de Dientes/uso terapéutico , Adulto , Anciano , Óxido de Aluminio/uso terapéutico , Química Farmacéutica , Ciclohexenos/administración & dosificación , Profilaxis Dental , Método Doble Ciego , Femenino , Humanos , Limoneno , Masculino , Persona de Mediana Edad , Dióxido de Silicio/uso terapéutico , Té/efectos adversos , Terpenos/administración & dosificación , Blanqueadores Dentales/administración & dosificación , Decoloración de Dientes/etiología , Decoloración de Dientes/prevención & control , Pastas de Dientes/administración & dosificación
5.
Arch Oral Biol ; 54(9): 817-22, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19616770

RESUMEN

OBJECTIVE: This in vitro study was undertaken to assess the effects of Galla chinensis extract on inhibition of enamel caries-like demineralization and to elucidate the role of the organic matrix of enamel in this process. DESIGN: Either regular or enamel disposed of its organic matrix both of bovine origin were exposed to a demineralizing solution for 3 days (pH 4.5). Specimes were additionally treated with either 4 g/L of G. chinensis extraction (GCE) or double distilled water (DDW) four times daily for 5 min each time. Regular enamel exposed accordingly to sodium fluoride (1g/L) during the demineralizing period served as positive control. After exposure mineral loss and lesion depth of all samples were analysed by transversal microradiography. One-way ANOVA and Student-Newman-Keuls test were used to compare the differences amongst groups. A factorial ANOVA was chosen to test the interaction between GCE and enamel organic matrix. RESULTS: Mineral loss and lesion depth of specimens in the positive control group were significantly lower compared to all other groups. Regular enamel treated with GCE showed significantly lower values compared to regular enamel treated with DDW or to enamel disposed of its organic matrix (p<0.05). These three groups revealed similar values (p>0.05). Significant interaction between GCE and enamel organic matrix with respect to both outcomes could be observed (p<0.05). CONCLUSIONS: G. chinensis inhibits enamel caries-like demineralization in vitro. However, its potential seems to be weaker compared to sodium fluoride. The organic matrix of enamel was shown to play a substantial role in the observed mechanism.


Asunto(s)
Cariostáticos/uso terapéutico , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/uso terapéutico , Extractos Vegetales/uso terapéutico , Desmineralización Dental/prevención & control , Animales , Áfidos , Bovinos , Caries Dental/patología , Caries Dental/prevención & control , Esmalte Dental/ultraestructura , Proteínas del Esmalte Dental/efectos de los fármacos , Solubilidad del Esmalte Dental/efectos de los fármacos , Dureza , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Microrradiografía/métodos , Rhus , Fluoruro de Sodio/uso terapéutico , Hipoclorito de Sodio/farmacología , Solventes/farmacología , Factores de Tiempo , Desmineralización Dental/patología
6.
Biomed Mater ; 4(3): 034102, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19498221

RESUMEN

Galla chinensis, a natural traditional Chinese medicine with main composition of tannic acid and gallic acid, is formed when the Chinese sumac aphid Baker (Melaphis chinensis bell) parasitizes the levels of Rhus chinensis Mill. Galla chinensis has shown the potential to enhance the remineralization of initial enamel carious lesion, but the mechanism is still unknown. This study was to investigate whether the enamel organic matrix plays a significant role in the potential of Galla chinensis to promote the remineralization of initial enamel caries. Bovine sound enamel blocks and non-organic enamel blocks were demineralized and exposed to a 12 day pH cycling. During the pH cycling, 30 specimens with the enamel organic matrix were randomly divided into three groups, and treated with 1 g L(-1) NaF (group A), 4 g L(-1) Galla chinensis extract (group B1) or double deionized water (group C1). Twenty specimens without the enamel organic matrix were randomly divided into two groups, and treated with 4 g L(-1) Galla chinensis extract (group B2) or double deionized water (group C2). The integrated mineral loss and lesion depth of all the specimens were analysed by transverse microradiography. The integrated mineral loss and lesion depth of group B1 were less than those of groups B2, C1 and C2, and there were no statistical differences among groups B2, C1 and C2. In conclusion, Galla chinensis can enhance the remineralization of initial enamel carious lesion, and the enamel organic matrix plays a significant role in this potential of Galla chinensis.


Asunto(s)
Matriz Ósea/efectos de los fármacos , Calcificación Fisiológica/efectos de los fármacos , Caries Dental/tratamiento farmacológico , Caries Dental/fisiopatología , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Animales , Bovinos , Estudios de Factibilidad , Técnicas In Vitro
7.
J Dent ; 36(12): 999-1004, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18829148

RESUMEN

OBJECTIVE: To evaluate the demineralization inhibition property of extracts and chemical fractions of Galla chinensis in vitro. METHODS: Seventy sound bovine enamels blocks were prepared and randomly divided into seven groups. These samples were pH-cycled for 12 times in 6 days. Each daily cycle included 2x 5 min application with one of the seven treatments: 1000 ppmFaq. (as NaF, positive control); deionized water (negative control); or 4000 ppm aqueous solutions of five G. chinensis extracts (GCEs): GCE, GCE-A, GCE-B, GCE-C or GCE-D. Surface enamel microhardness was measured on the enamel blocks before and after pH-cycling, and the reduction of surface microhardness (DeltaSMH) was calculated. The acidic buffers were retained for calcium analysis. RESULTS: There were significant differences between the GCE groups and the two controls (p<0.01). Among all the GCE groups, the reduction of surface microhardness (DeltaSMH) in GCE group was the least (p<0.01). No significant differences were found between the GCE group and GCE-C group in CDR, as well as the other three GCE groups (GCE-A, GCE-B and GCE-D) (p>0.05). CONCLUSIONS: The present study has demonstrated the potential of the GCE to effect the demineralization under dynamic pH-cycling conditions. None of the chemical fractions was as effective as GCE. Combined with its anti-bacterial properties, the demineralization inhibition of GCE suggests that this material could be a useful source for the development of promising anti-cariogenic agents.


Asunto(s)
Cariostáticos/uso terapéutico , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/uso terapéutico , Extractos Vegetales/uso terapéutico , Rhus , Desmineralización Dental/prevención & control , Animales , Tampones (Química) , Calcio/análisis , Bovinos , Solubilidad del Esmalte Dental/efectos de los fármacos , Dureza , Concentración de Iones de Hidrógeno , Extractos Vegetales/análisis , Distribución Aleatoria , Fluoruro de Sodio/uso terapéutico
8.
J Dent ; 36(5): 369-73, 2008 May.
Artículo en Inglés | MEDLINE | ID: mdl-18308448

RESUMEN

OBJECTIVE: To investigate the effect of chemical compounds of Galla chinensis and their combined effects with fluoride on remineralization of artificial early enamel caries. METHOD: Bovine enamel blocks with in vitro produced initial lesion were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4x 1min applications with one of six treatments group A: 1000ppm F aq. (as NaF, positive control); group B: deionized water (DDW, negative control); group C: 4000ppm crude aqueous extract of G. chinensis (GCE); group D: 4000ppm gallic acid; group E: 4000ppm GCE with 1000ppm F; group F: 4000ppm gallic acid with 1000ppm F. The enamel specimens were analyzed by transverse microradiography. Integrated mineral loss (IML) and lesion depth (LD) were measured and mineral content in the surface layer and lesion body were calculated. RESULTS: The LD and IML were significantly different among the different treatment groups. GCE and gallic acid could reduce LD and IML significantly compared with DDW. Groups E and F showed the shallowest lesion. In the groups with gallic acid (groups D and F), mineral deposition predominated in the surface layer. In groups with GCE (groups C and E), more mineral deposition occurred in the lesion body. CONCLUSION: The chemical compounds of G. chinensis were able to enhance remineralization of dental enamel. They also had combined effects with fluoride on enhancing remineralization.


Asunto(s)
Cariostáticos/uso terapéutico , Caries Dental/prevención & control , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/uso terapéutico , Fluoruros/uso terapéutico , Remineralización Dental/métodos , Animales , Cariostáticos/administración & dosificación , Bovinos , Caries Dental/patología , Esmalte Dental/patología , Combinación de Medicamentos , Medicamentos Herbarios Chinos/administración & dosificación , Fluoruros/administración & dosificación , Ácido Gálico/administración & dosificación , Ácido Gálico/uso terapéutico , Concentración de Iones de Hidrógeno , Microrradiografía , Minerales/análisis , Fluoruro de Sodio/administración & dosificación , Fluoruro de Sodio/uso terapéutico , Factores de Tiempo
9.
Arch Oral Biol ; 52(9): 869-75, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17382894

RESUMEN

Nidus Vespae (the honeycomb of Polistes olivaceous, P. japonicus Saussure and Parapolybiavaria fabricius) have been extensively used in traditional Chinese medicine, given their multiple pharmacological activities, including antimicrobial, anti-inflammatory, anti-virus, anti-tumor and anesthetic properties. The present study evaluated the anti-glucosyltransferases (GTFs) activity, anti-adherence and anti-biofilm properties of 95% ethanol/water extract, cyclohexane/ethyl acetate, petroleum ether/ethyl acetate and chloroform/methanol fractions of Nidus Vespae. Chloroform/methanol fraction showed a remarkable capacity for inhibiting the adherence of Streptococcus mutans ATCC 25175 to saliva-coated hydroxyapatite disc (S-HA) at sub-MC concentrations. In addition, the Nidus Vespae extract and chemical fractions significantly inhibited the activity of cell-associated and extracellular GTFs at sub-MIC concentrations, and the chloroform/methanol fraction was the most effective one. For the anti-biofilm activity assays, minimum biofilm inhibition concentrations (MBIC50) and minimum biofilm reduction concentrations (MBRC50) were determined using the microdilution method. The chloroform/methanol fraction showed the highest anti-biofilm activities with a MBIC50 of 8mg/ml and a MBRC(50) of 16mg/ml against Streptococcus mutans ATCC 25175. The significant inhibition of GTFs activity and biofilm formation demonstrated by Nidus Vespae shows it to be a promising natural product for the prevention of dental caries.


Asunto(s)
Antiinfecciosos/farmacología , Adhesión Bacteriana/efectos de los fármacos , Biopelículas/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Glucosiltransferasas/efectos de los fármacos , Extractos Vegetales/farmacología , Streptococcus mutans/efectos de los fármacos , Avispas , Ceras/farmacología , Animales , Antiinfecciosos/administración & dosificación , Antiinfecciosos Locales/farmacología , Clorhexidina/farmacología , Película Dental/microbiología , Relación Dosis-Respuesta a Droga , Medicamentos Herbarios Chinos/administración & dosificación , Durapatita/química , Glucanos/análisis , Humanos , Extractos Vegetales/administración & dosificación , Polisacáridos Bacterianos/efectos de los fármacos , Streptococcus mutans/enzimología , Streptococcus mutans/fisiología
10.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 41(10): 616-7, 2006 Oct.
Artículo en Chino | MEDLINE | ID: mdl-17129452

RESUMEN

OBJECTIVE: To evaluate the effect of chemical compounds extracted from Galla chinensis on enamel surface rehardening in vitro. METHODS: Sixty bovine enamel blocks with early carious lesions were randomly divided into six groups: group1 treated NaF (positive control); group2 with GCE; group3 with GCE-B; group4 with GCE-B1; group5 with GCE-B2 and group6 with deionized water (negative control). The lesions were subjected to a pH-cycling regime for 12 days. Surface enamel microhardness was measured on the enamel blocks before and after demineralization. After pH-cycling, and the percentage of surface microhardness recovery (SMHR) was calculated. RESULTS: Obvious increase of the surface hardness of the enamel was observed in all the treatments except GCE-B2 and deionized water (P < 0.05). CONCLUSIONS: The present study demonstrates the potential of the three GCEs (GCE, GCE-B and GCE-B1) to effect net rehardening of artificial carious lesions under dynamic pH-cyclic conditions.


Asunto(s)
Caries Dental/tratamiento farmacológico , Esmalte Dental/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Ácido Gálico/farmacología , Animales , Bovinos , Técnicas In Vitro , Remineralización Dental
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