Ya-Yun Lee

National Yang Ming University, T’ai-pei, Taipei, Taiwan

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Publications (13)28.16 Total impact

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    ABSTRACT: Background: Areca quid chewing increases the prevalence of periodontal diseases. Areca nut extract (ANE) inhibits the phagocytic activity of human neutrophils. This in vitro study investigated the effects of ANE on complement and antibody-opsonized phagocytosis by neutrophils. Expression of complement receptors, Fc receptors and F-actin in ANE-treated neutrophils was also analyzed. Methods: The viability of ANE-treated neutrophils was determined using the propidium iodide staining method. The possible effects of ANE on the expression of complement receptors and Fc receptors were examined using an immunofluorescence staining method followed by flow cytometry and confocal laser scanning microscopy. The phagocytic activity of neutrophils against complement or immunoglobulin (IgG)-opsonized fluorescent beads was analyzed using flow cytometry. Expression of F-actin was determined using confocal laser scanning microscopy. Results: ANE significantly inhibited the production of complement receptor (CR1, CR3 and CR4) and Fc receptors (FcγRII and FcγRIII) in a concentration-dependent manner. Treatment of neutrophils with ANE significantly impaired their ability to phagocytose fluorescent beads. ANE also inhibited phagocytosis of fluorescent beads that were opsonized by complement or IgG. Moreover, expression of F-actin was inhibited after ANE treatment. Conclusions: ANE inhibited the complement and IgG-mediated neutrophil phagocytosis which may result from reduction of the expression of complement receptors, Fc receptors and F-actin formation after ANE treatment. The findings suggest that areca nut chewing may jeopardize the defensive functions of neutrophils and affect the periodontal health.
    Journal of Periodontology 12/2013; · 2.40 Impact Factor
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    ABSTRACT: Background/purpose As a pulp capping agent, mineral trioxide aggregate (MTA) is commonly applied on inflamed tissues that present with a variety of immunocompetent cells, including neutrophils. Neutrophils are a major source of matrix metalloproteinases (MMPs) that have been implicated in the process of dentinogenesis. This study aimed to investigate the impact of MTA on human neutrophils. Materials and methods Freshly purified human neutrophils were incubated with MTA or another commonly used filling material, intermediate restorative material (IRM). The viability and phagocytic activity of treated neutrophils were assessed by flow cytometry. In addition, the morphology of neutrophils was observed under scanning electron microscopy and the production of MMP-9 was analyzed by gelatin gel zymography. Results Treatment with MTA did not affect the viability, morphology, and phagocytic activity of neutrophils significantly. However, MTA increased the production of MMP-9 in neutrophils. However, IRM reduced the viability and altered cell morphology of the neutrophils. Conclusion MTA may participate in the pulpal inflammatory response by increasing MMP-9 production of neutrophils. These signals may facilitate the repair of dental pulp tissue.
    Journal of dental sciences 12/2013; 8(4):378–384. · 0.35 Impact Factor
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    ABSTRACT: The innate immune response is activated by recognition of microbial components through specific pattern recognition receptors including nucleotide-binding oligomerization domain (NOD)-like receptors. However, the regulation of NOD-1 in inflamed human dental pulp remains poorly understood. This study aimed to evaluate the expression of NOD-1 in healthy and inflamed human dental pulps. In addition, the secretion of chemokines induced by NOD-1 and the related signaling pathways were studied. Samples of human dental pulp tissues were obtained from freshly extracted wisdom teeth. The protein localization of NOD-1 in the pulp tissues was detected by immunohistochemistry. In addition, human dental pulp fibroblasts were stimulated with NOD-1 agonist γ-D-glutamylmeso-diaminopimelic acid. Production of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) was determined by an enzyme-linked immunosorbent assay. The involvement of mitogen-activated protein kinase (MAPK) signaling pathways was examined by Western blot analysis, and the association of MAPK signaling with chemokine production was determined. The results demonstrated the expression of NOD-1 in normal dental pulp, and up-regulated NOD-1 expression was observed in inflamed dental pulp. On stimulation with NOD-1 agonist, production of IL-8 and MCP-1 was induced in a dose-dependent manner. Moreover, phosphorylation of p38 MAPK and Jun N-terminal kinase (JNK) was enhanced by stimulation of NOD-1. With the treatment of p38 MAPK and JNK inhibitors, the NOD-1-induced IL-8 production was suppressed. In response to microbial invasion, the expression of NOD-1 can be regulated in a ligand-inducible manner. NOD-1 might participate in pulp inflammation through chemokine production via MAPK signaling pathways.
    Journal of endodontics 10/2011; 37(10):1370-5. · 2.95 Impact Factor
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    ABSTRACT: The purpose of this study was to examine the effects of downhill walking training on gait and thoracic kyphosis in patients with Parkinson's disease. Thirty-three patients with Parkinson's disease were randomized into an experimental group (n = 16) or a control group (n = 17). Subjects in the experimental group underwent 4-wks of downhill walking training, whereas subjects in the control group received conventional therapy for 4 wks. Gait parameters, thoracic kyphosis, and muscle strength of knee were measured at pretraining, posttraining, and at 1-mo follow-up. There were significant interaction effects between group and time of evaluation on gait parameters and thoracic kyphotic curve. There was also a significant group effect for muscle strength of knee extensors. Our results suggest that downhill walking training is beneficial for improving gait performance in patients with Parkinson's disease and may contribute to maintenance of thoracic posture in these subjects.
    American journal of physical medicine & rehabilitation / Association of Academic Physiatrists 09/2010; 89(9):706-14. · 1.56 Impact Factor
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    ABSTRACT: Areca quid chewing increases the prevalence of periodontal diseases. Areca nut extract (ANE) inhibits the defensive functions of human polymorphonuclear leukocytes (PMNs). This in vitro study investigates the effects of ANE on the production of cyclooxygenase (COX)-2 and the inflammatory mediator prostaglandin E(2) (PGE(2)) by PMNs. The possible effects of ANE on the production of COX-2 were examined using Western blotting analysis. The viability and production of PGE(2) of treated PMNs were determined using the propidium iodide staining method and the competition enzyme assay, respectively. The possible pathways involved were also examined using the COX-2 inhibitor (NS398), the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N, N, N', N'-tetraacetic acid tetrakis (acetoxymethyl ester) (BAPTA-AM), the p38 mitogen-activated protein kinase (MAPK) inhibitor (SB203580), and the extracellular signal-regulated protein kinase (ERK) inhibitor (U0126). The effects of ANE on the viability or PGE(2) production were statistically assessed using a one-way analysis of variance and Tukey multiple-comparison intervals with alpha = 0.05. ANE significantly induced the production of PGE(2) in a time- and concentration-dependent manner. This induction resulted from an increased expression of COX-2. Moreover, the application of BAPTA-AM, SB203580, and U0126 statistically significantly suppressed the induction of PGE(2). ANE induced the production of PGE(2). The activation of the intracellular calcium concentrations, p38 MAPK, and ERK may be involved in the inducing effects of ANE on PMNs. The findings suggest that areca nut chewing may induce an inflammatory response and affect the periodontal health of consumers.
    Journal of Periodontology 05/2010; 81(5):758-66. · 2.40 Impact Factor
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    ABSTRACT: In this case report, we present a maxillary first molar with six canals. A 40-year-old male patient was referred for non-surgical root canal therapy of tooth 16. Under magnification of a surgical operating microscope, a unique morphology with double canal systems in each root was identified. The morphology was characterized by a single palatal root with two canals joining in the apical third, two mesiobuccal canals, and two distobuccal canals with one orifice and two separate foramina.
    Journal of Dental Sciences. 12/2009; 4(4):198–201.
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    ABSTRACT: This study compared bacterial penetration through guided tissue regeneration (GTR) membranes impregnated with antibiotics. Three barrier membranes, expanded polytetrafluoroethylene (ePTFE) membrane, collagen membrane, and glycolide fiber composite membrane, were loaded with amoxicillin or tetracycline. The penetration of Streptococcus mutans and Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) through the GTR membranes was achieved using a device consisting of an inner tube and an outer bottle filled with culture media. The penetration of S. mutans or A. actinomycetemcomitans into the inner tubes significantly decreased with all of the antibiotic-loaded membranes compared to membranes without antibiotics. However, differences were found in the behavior of the three membranes. The antibiotic-loaded ePTFE membranes showed the best barrier effect. Moreover, the inhibitory effect of tetracycline on S. mutans was greater than that of amoxicillin for all GTR membranes. Furthermore, the inhibitory effect of tetracycline on A. actinomycetemcomitans was lower than that of amoxicillin with the glycolide fiber membrane. The results showed that penetration of S. mutans and A. actinomycetemcomitans through amoxicillin- or tetracycline-loaded ePTFE membrane, glycolide fiber membrane, and collagen membrane was delayed and/or reduced. Thus, incorporation of an antibiotic into the membrane may be of value when controlling membrane-associated infection during GTR therapy.
    Journal of Periodontology 10/2009; 80(9):1471-8. · 2.40 Impact Factor
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    ABSTRACT: The prevalence of extra distolingual (DL) roots in mandibular first molars in Chinese population is about 20%. The purpose of this study was to evaluate the difference of root length and root curvatures between distobuccal (DB) and DL roots of three-rooted mandibular first molars in a Taiwanese (Chinese) population. Of the 293 extracted mandibular first molars, DL roots were present in 29 (9.9%) teeth. Excluding teeth with fractured DB or DL roots, 21 mandibular first molars were further investigated. DB and DL root lengths were measured from the lower level of furcation at the distal surface to the root apex. The curvature of the DL root was measured on mesial-distal and buccal-lingual radiographs by Schneider's technique. The DL roots were significantly (p < 0.001) shorter than the DB roots with an average of 1.48 +/- 0.81 mm. Most DL roots had a greater curvature in a buccal-lingual orientation (36.35 degrees +/- 9.38 degrees ) than a mesial-distal orientation (9.24 degrees +/- 6.10 degrees ) and 28.57% of the curved DL roots had the curvature at the apical one third (p < 0.001). The results of this study verified the characteristics of shorter root length and severe buccal-lingual inclination of DL roots in three-rooted mandibular first molars.
    Journal of endodontics 06/2009; 35(5):643-5. · 2.95 Impact Factor
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    ABSTRACT: This study examined the relationships between gait and dynamic balance in people with early-stage Parkinson's disease (PD). We assessed 18 participants diagnosed with stage I-II idiopathic PD and 17 healthy age-matched volunteers. Temporo-spatial gait variables were analyzed using the GAITRite system and participants were asked to walk at a comfortable walking speed. Dynamic balance was assessed using the Balance Master. Movement velocity (MV), maximal excursion (ME), and directional control (DC), obtained through the limits of stability test, quantified dynamic balance. People with early stage PD exhibited significantly slower walking speed, shorter stride length, and smaller forward MV than the comparison group. In the PD group, stride length and speed significantly correlated with forward MV, forward ME, and forward DC. Thus, in people with early PD, gait speed and stride length are correlated with dynamic balance, particularly in the forward direction in standing.
    Gait & Posture 06/2008; 27(4):611-5. · 1.97 Impact Factor
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    ABSTRACT: Eugenol-containing restorative materials are commonly used for vital pulp therapy. A well-regulated host defense response is pivotal for the success of vital pulp therapy. The present study was to assess the effects of eugenol on the antimicrobial functions of polymorphonuclear leukocytes (neutrophils). Treatment with eugenol (< or = 1.25 mmol/L) for 30 minutes did not significantly affect the viability of neutrophils. However, preincubation of neutrophils with eugenol (1.25 mmol/L and 2.5 mmol/L) abolished their bactericidal activity against oral pathogens Streptococcus mutans and Actinobacillus actinomycetemcomitans. In addition, through the suppression of the extracellular release of myeloperoxidase and the intracellular production of reactive oxygen species, eugenol at sufficient concentrations impaired the activation of neutrophils by cytochalasin B and fMet-Leu-Phe (CB/fMLP). These results suggested that the antimicrobial functions of neutrophils were interfered by eugenol, and the inhibitory effects of eugenol (< or = 1.25 mmol/L) were not due to direct killing of neutrophils.
    Journal of Endodontics 03/2008; 34(2):176-80. · 2.93 Impact Factor
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    ABSTRACT: Because eugenol is a major component of root canal sealers and retrograde filling materials, its effects on periapical bone healing are therefore of concern. In this study, the effects of eugenol on the activation of nuclear factor kappa B (NF-kappaB) and the expression of cyclooxygenase-2 (COX-2) in human osteoblasts were investigated. The results showed that eugenol activated the nuclear translocation of NF-kappaB. In addition, COX-2 protein expression in osteoblasts was induced by eugenol in a dose-dependent manner. Furthermore, the eugenol-modulated COX-2 expression was inhibited by an NF-kappaB inhibitor, N-acetylcysteine. Taken together, eugenol might induce COX-2 expression through the activation of NF-kappaB in human osteoblasts. These results suggest that eugenol might be involved in periapical healing by impairing the functions of osteoblasts.
    Journal of Endodontics 11/2007; 33(10):1177-82. · 2.93 Impact Factor
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    ABSTRACT: Eugenol is commonly used as an analgesic agent during acute pulpitis and is a major component of root canal sealers. Despite the frequent applications of eugenol in the practice of dentistry, little is known about the role of eugenol under the status of inflammation. This study was aimed to investigate the influence of eugenol on human macrophages (U937) under the stimulation of lipopolysaccharide (LPS). Eugenol was shown to block the release of the bone resorbing mediators, including interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and prostaglandin E2 from LPS-stimulated macrophages. In contrast, eugenol alone did not alter the expression levels of these proinflammatory mediators in macrophages. Consistent with downregulation of bone-resorbing mediators, eugenol suppressed the messenger RNA expression of LPS-induced IL-1beta, TNF-alpha, and cyclooxygenase-2 in macrophages. The results suggest a potential anti-inflammatory effect of eugenol in the acute inflamed pulps and apical periodontitis.
    Journal of Endodontics 07/2007; 33(6):698-702. · 2.93 Impact Factor
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    ABSTRACT: A higher prevalence of periodontal diseases among areca chewers than non-areca chewers has been demonstrated. Neutrophils, representing the first line of the host defense mechanism against microbial infection, play important roles in maintaining periodontal health. This study determined the possible effects of areca nut on phagocytosis, chemotaxis, and adhesion of human neutrophils. Aqueous extracts of ripe areca nut without husk (rANE) and fresh and tender areca nut with husk (tANE) were examined for their effects on neutrophil phagocytosis using flow cytometry and confocal laser scanning microscopy. The effects of rANE and tANE on chemotaxis and adhesion of neutrophils to human aortic endothelial cells were examined using fluorescence-labeled neutrophils. Both rANE and tANE inhibited the phagocytic activity of neutrophils in a dose-dependent manner. The levels of internalized fluorescent bacteria in neutrophils decreased after ANE treatment. However, exposure of neutrophils to rANE and tANE stimulated the chemotaxis activity of neutrophils to N-formyl-Met-Leu-Phe (fMLP) and enhanced adhesion of neutrophils to human aortic endothelial cells in a dose-dependent manner. Moreover, treatment of neutrophils with rANE was more effective than incubation with tANE. Components of areca nut inhibited phagocytosis activity of neutrophils but enhanced chemotaxis and adhesion of neutrophils. Alterations in functions of neutrophils may lead to signs of clinical diseases associated with areca chewing. The components in ANEs that are responsible for these observations remain to be elucidated.
    Journal of Periodontology 05/2006; 77(4):579-85. · 2.40 Impact Factor

Publication Stats

107 Citations
28.16 Total Impact Points


  • 2007–2013
    • National Yang Ming University
      • • Institute of Oral Biology
      • • Department of Dentistry
      T’ai-pei, Taipei, Taiwan
  • 2009–2010
    • Taipei Veterans General Hospital
      • Endodontics & Periodontics Division
      T’ai-pei, Taipei, Taiwan