cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.14457/cu.the.2013.2066
title: Anti-hepatotoxic substances from Thunbergia Laurifolia and Phyllanthus Amarus
DOI: 10.14457/cu.the.2000.369
title: Molecular loci and glycosylation of dehydro-histidinohydroxymerodesmosine in non-mineralized type I collagen fibrils

description: The covalent intermolecular cross-linking is essential in providing collagen matrices with physicochemical properties. Dehydro-histidinohydroxymerodesmosine is a major tetravalent collagen cross-link present in most non-mineralized tissues. Despite its abundance, this cross-link has been poorly characterized. The objectives of this study were to isolate the cross-linked peptides, determine the molecular loci and evaluate the state of glycosylation of the cross-link. The peripheral layer of the turkey leg tendon (never-mineralized collagenous tissue) was reduced with tritiated sodium borohydride, subjected to sequential enzymatic/chemical digestion and several cross-linked peptides were isolated by means of HPLC. Based on the amino-terminal sequence, amino acid composition and mass spectrometric analyses of the purified peptides, three molecular loci were identified. They are lysyl aldehyde (alpha1-9N) X lysyl aldehyde (alpha1-9N) X hydroxylysine (alpha1-930) X histidine (alpha2-935), lysyl aldehyde (alpha1-9N) X lysyl aldehyde (alpha2-6N) X hydroxylysine (alpha1-930) X histidine (alpha2-935) and lysyl aldehyde (alpha1-9N) X lysyl aldehyde (alpha2-6N) X hydroxylysine (alpha1-930) X histidine (alpha1-932). The data indicate that the aldol involved in the cross-link is derived from the amino-terminal telopeptidyl aldehydes, and that the hydroxylysine on an alpha1 chain (residue 930) and histidine from alpha2-935 is the preferred cross-linking site. The latter suggests a stereospecific packing of the type I collagen molecules in the fibril. In addition, chemical and mass spectroscopic analyses of the peptides and their acid/base hydrolysates revealed that the hydroxylysine residues (alpha1-930) that are involved in the formation of this complex cross-link were not glycosylated. These results suggest that the carbohydrate moiety on the alpha1-930 hydroxylysine may have a role in regulating the cross-link formation.
DOI: 10.14457/cu.the.2000.370
title: Collagen requirements of cell surface activation of gelatinase A by fibroblasts

description: Type I collagen is one of a few physiological substances that caninduce the activation of MMP-2, a tissue degrading enzyme involved invarious physiological and pathological phenomena. In the present study,specificity for the types and structures of collagen capable of thisinduction has been studied. MMP-2 activation was monitored by zymography.Treatment of the cell cultures by addition of collagen in solution, insteadof growing cells oil collagen gels, was developed to avoid unknown effectsof trapped serum proteins, and for ease in manipulating collagenconcentrations. Addition of recombinant, purified, or partially purifiedcollagens into the culture of normal human skin fibroblasts demonstratedthe specificity of fibrillar-type collagen for induction of MMP-2activation. Reduction of MMP-2 fibril formation by treatment of thecultures with dry monomeric or alkali-treated collagen, or afibril-inhibitory collagen peptide, abrogated the MMP-2 activation.Moreover the periodate-sensitive features of collagen, such as thecarbohydrate molecules, were required for the appropriate cellular responseto collagen, whereas the presence or absence of telopeptide made littledifference to induction of MMP-2 activation. Both mRNA and protein levelsof the prominent MMP-2 activator, MT1-MMP, were consistently correlatedwith the amount of MMP-2 activation. The importance of MT1-MMP wassupported by the relative lack of MMP-2 activation after collagenstimulation of MM1-MMP% mouse fibroblasts. The role of collagen in this process was further assessed inascorbate-treated fibroblast cultures, which secrete and deposit endogenouscollagen, and better represent ~iin vivo~i conditions. Endogenous collageninduced a similar profile of MMP-2 activation and MT1-MMP expression asexogenous collagen. Temporal resolution of transcriptional andnon-transcriptional regulation of MT1-MMP by collagen was also observed inthis culture system. The essential role of collagen for MMP-2 activation inthis system was confirmed with prolyl-4-hydroxylase inhibitors, and withfibroblasts derived from the Mov-13 mouse, in which the collagen (+,a)1 (I)gene is not expressed. Inhibition of the endogenous collagen cross-linkingby BAPN had no effect on the activation of MMP-2. Surprisingly,pC-procollagen, produced by Mov13-5 CM mouse fibroblasts transfected with adefective (+,a)(,1)(I) chain, retained the ability to induce MMP-2activation, despite their inability to form fibrils. This result suggestedthat a non-fibrillar collagen structure can induce MMP-2 activation.Furthermore, ascorbate-treated cultures of MT1-MMP -/- mouse fibroblastsshowed considerable MMP-2 activation, which appears to be due to anintracellular activation. Collectively this study confirms an importantrole of type I collagen in both MT1-MMP- dependent and - independent activation ofMMP-2, and the ability of non-fibrillar collagen structures to induce MMP-2activation in ~iin vivo~i-simulated cultures of fibroblasts.
DOI: 10.14457/cu.the.2002.572
title: Interaction of Actinobacillus actinomycetemcomitans with antigen-presenting cells (dendritic cells)

description: It becomes clear that the interaction between dendritic cells (DCs) and pathogens is a significant factor in determining the effectiveness of the immune response and the outcome of disease. Periodontitis is a chronic bacterial infection which is characterized by a destructive inflammatory process affecting periodontal tissues and bone. The immunopathogenesis of the disease involves the interaction between host defense mechanisms and Gram negative bacteria and their products such as lipopolysaccharide (LPS) in dental plaque. We therefore attempted to investigate the interaction of LPS derived from Actinobacillus actinomycetemcomitans, one of the key periodontal pathogens, with dendritic cells. Immature dendritic cells were generated from CD14+ monocytes culturing in medium supplemented with granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4. These immature DCs when stimulated with A. actinomycetemcomitans LPS in vitro for 24 h. led to cell maturation associated with the enhanced expression of co-stimulatory molecules (CD40 and CD80), a maturation marker (CD83) and human leukocyte antigen (HLA)-DR. A. actinomycetemcomitans LPS at 1,000 ng/ml induced minimally production of cytokines. Moderate amount of tumor necrosis factor-a was consistently observed, however, we could not detect any IL-12 production. In mixed leukocyte reaction, A. actinomycetemcomitans LPS treated DCs promoted T-helper 1 (Th1) response as indicated by predominant production of interferon-g but not IL-4 and IL-10 by allogeneic T cells. In conclusion, our study demonstrated that we were able to generate DCs from flow cytometrically sorted CD14+ monocytes in culture with GM-CSF and IL-4. The immature DCs became mature when stimulated with A. actinomycetemcomitans LPS and capable to drive Th1 response. However, it is too early to draw any conclusion concerning the effect of A. actinomycetemcomitans on DC induced Th response. How this Th development associated with the pathogenesis of periodontitis would require further investigation.
DOI: 10.14457/cu.the.2002.573
title: Activation of matrix metalloproteinase-2 (MMP-2) by supernatant of anaerobic bacteria cultivated from periodontal pockets

description: It has been reported that host-derived enzymes, matrix metalloproteinases (MPs), play a major role in periodontal tissue destruction. The purpose of this study was to examine the effects of bacterial supernatant from mixed gram-negative anaerobic bacteria and Porphyromonas gingivalis (P. gingivalis) cultivated from periodontal pockets nad lipopolysaccharide (LPS) of P. gingivalis on expression and activation of MMP-2 in culture of human gingival fibroblasts (HGF) and human periodontal ligament (HPDL) cells. HGF and HPDL were treated with supernatant of mixed gram-negative anaerobic bacteria of supernatant of P. gingivalis for 48 hours. RT-PCR and Western analysis were used to analyze MMP-2 expression at transcriptional and translational level, respectively. The level of MMP-2 activation was monitored by gelatin zymography. It was found that supernatant of mixed gram-negative anaerobes and supernatant of P. gingivalis could indeuce MMP-2 activation, but could not alter the mRNA and protein levels of MMP-2. The MMp-2 activation was inhibited by NF-kB inhibitor and metal chelating agents (EDTA, phenanthroline), but not by serine protease inhibitor (aprotinin, PMSF). These results indicated that HGF/HPDL could directly response to the bacterial supernatant by demonstrating the active form of MMP-2. The next experiment, HGF and HPLD were treated with LPS extracted from P. gingivalis for 48 hours. The results indicated that P. gingivalis LPS could induce MMP-2 activation in both cell types. The mechanism of MMP-2 activation induced by LPS was different from those induced by the supernatant, since the activation process was not inhibited by EDTA or phenanthroline. However, it can be partially inhibited by NF-kB inhibitor and completely blocked by serine protease inhibitor. In addition, LPS induced MMP-2 activation was inhibited by aprotinin and PMSF. These results revealed that the ability of LPS to activate MMP-2 may occur through 2 different pathways, the NF-kB dependent pathway and the serine protease-dependent pathway. In conclusion, bacterial supernatant of mixed gram-negative anaerobes and P. gingivalis, and LPS of P. gingivalis can activate MMP-2 in HGF and HPDL cells by different mechanism. It is possible that secreted bacterial products of gram-negative anaerobes and P. gingivalis play a crucial role in periodontal tissue destruction, by directly activate MMP-2 secreted from HGF and HPDL cells.
DOI: 10.14457/cu.the.2003.1292
title: The influence of silane coupling agent on hydrolytic durability of silica-contained composite resin determined by flexural properties

description: Using silanated filler in making dental resin composite results in the superior performance in both mechanical properties and durability of composite. The objectives of this study were to elucidate the effect of amount of silane coupling agent, gamma methacryloxypropyltrimethoxysilane, the heat used in silanation process and pH of silanating solution on flexural properties and hydrolytic durability of composite. Flexural properties were obtained from specimens' preparation following ISO 4049:2000 and hydrolytic durability was obtained from subjecting the specimens in Soxhlet's extractor. An organic elemental analysis, a Fourier transform infrared spectroscopy, a thermogravimetric analysis and a differential scanning colorimeter accompanied with a scanning electron microscope were utilized as the analyzing tools to understand the characteristics of the silane coupling agent on silica surface. Flexural properties of composite were fairly affected by the amount of silane providing that certain amount existed on the filler surface. Mean while, the flexural properties and hydrolytic durability were significantly depended upon the temperature used indrying the filler. Unlike, the heating effect, pH also showed the same trend as the effect of amount. The results were drawn from statistic analysis at p&lt;0.05. It was concluded that silanation of filler is a prerequisite for superior performance of composite with hydrolytic stability. The amount of silane coupling agent covering filler and pH of silanating solution are not strongly affected the flexural properties and hydrolytic durability. The application of heating less than 80 ํC in drying filler for 3 hours resulted in better flexural properties and more hydrolytic durable composite.
DOI: 10.14457/cu.the.2003.1293
title: The effect of post and cement types on vertical root fracture resistance in endodontically treated teeth

description: This in vitro study evaluated the vertical fracture resistance of human extracted maxillary central incisors in six experiment groups. Two different types of luting cement (resin and zinc phosphate cement) and three different post materials (stainless steel, carbon fiber, and casted non-precious metal post) were used. The load was applied vertically at the cross-head speed 0.5 mm/min. All groups showed vertical root fracture except root that restored with cast post and core. Carbon fiber post cemented with resin cement showed the highest mean vertical fracture load at 3,517.30 +- 354.34 N, followed by stainless steel post cemented with resin cement, 3,368.90 +- 236.91 N, and carbon fiber post cemented with zinc phophate cement, 2,830.90 +- 236.91 N, respectively. Stainless steel post cemented with zinc phosphate cement provided the lowest mean vertical fracture load (2,549.60 +- 356.19 N). Statistic analysis by 2-way ANOVA (P is less than or equal to 0.05) showed that types of cement have an influence on vertical root fracture load. On the other hands, types of post showed no effect on vertical fracture load. There is also no interaction of post types and cement types on vertical fracture load. The majority of vertical root fracture patterns occurred in labio-lingual direction. The fracture line did not extend further than level of the post tip. Furthermore, there was no root canal cement or luting cement extruded into the fracture surface in every group of samples.
DOI: 10.14457/cu.the.2004.1478
title: The effect of type I collagen and insulin-like growth factor-I on osteopontin expression in human periodontal ligament cells

description: Extracellular matrix and growth factors might be the crucial factors that regulate healing and regenerating process in human periodontal ligament (HPDL) cells. The purpose of this study was to examine the effects of type I collagen and IGF-I on OPN expression in HPDL cells. Cells were cultured on plastic or type I collagen-coated plates for 48 hours, then cell extracts were collected. RT-PCR and Western blot analysis were used to analyze OPN expression at transcriptional and translational level, respectively. It was found that OPN expression was significantly decreased when cells were cultured on collagen-coated plates and this effect could be diminished by blocking with an inhibitory antibody to [beta]1 integrin. This result indicates that the inhibitory effect on the OPN expression exerted by type I collagen is signaled through [beta]1 integrin receptor. We also found that after HPDL cells were treated with 5 ng/ml of IGF-I, OPN expression was increased in cells grown on collagen-coated plates but not in uncoated condition. This result implies that IGF-I can attenuate the inhibitory effect of type I collagen on OPN expression in HPDL cells. In the last experiment, the cells were treated with the combination of inhibitory antibody to [beta]1 integrin and IGF-I. The result showed that OPN expression was increased to the same level as in the group treated with the inhibitory antibody to [beta]1 integrin or IGF-I alone. This result suggests that the effect of IGF-I associated in counteracting the inhibitory signal from type I collagen mediated by [beta]1 integrin. In conclusion, type I collagen inhibited OPN expression in HPDL cells via [beta]1 integrin and IGF-I can attenuate this inhibitory effect. It is possible that type I collagen and IGF-I play a role in periodontal regeneration by regulating the expression of the OPN in HPDL cells.
DOI: 10.14457/cu.the.2004.1479
title: Effects of IL-17 and IFN-gamma on human gingival fibroblasts

description: Periodontitis is a bacterial infection characterized by chronic gingival inflammation, which leads to the loss of tooth-supporting tissues. Dense infiltration of activated memory T cells and high levels of their cytokines were consistently detected in periodontal lesions. Although T cells have been considered to be central to both progression and control of chronic inflammatory periodontal diseases, the definite contribution in local immunoregulation has not been fully clarified. Recent observations showed the presence of IL-17, a novel T cell cytokine, and IFN-gamma in the inflamed periodontal tissues. Therefore, in this present study we investigated the immunostimulatory role of IL-17 and IFN-gamma on human gingival fibroblasts (HGF) which were obtained from clinically healthy periodontal tissues. Various concentrations of IL-17, IFN-gamma, or the combination of these two cytokines were added to HGF cultures. The expression of CD40 and HLA-DR was assessed by flow cytometry and IL-8 production was determined by ELISA. Our results demonstrated that IFN-gamma markedly up-regulated HLA-DR and minimally up-regulated CD40 expression on HGF. IL-17 did not induce the expression of both molecules and did not enhance IFN-gamma-induced CD40 and HLA-DR expression on HGF. Unlike IFN-gamma, IL-17 induced IL-8 production from HGF. When combined, IFN-gamma synergistically enhanced IL-17-induced IL-8 production. This enhancement was detected in all HGF cell lines at a higher dose of IL-17 (500 ng/ml) whereas at lower doses (5 and 50 ng/ml), heterogeneous response was observed. The findings of heterogeneity in IL-8 production by HGF in response to the combination of IL-17 and IFN-gamma are interesting and may explain the variation in host response in disease susceptibility or disease progression in periodontitis. Clearly, further investigation into this issue is needed.
DOI: 10.14457/cu.the.2004.1480
title: Comparison of gene expression related to maxillary incisor development between the wild type and the homozygous rsey rats with maxillary supernumerary incisors

description: This study aims to investigate the developmental process of the maxillary incisor tooth in the wild type SD and in the homozygous rat small eye. Rat small eyes; rSey; is inherited a dominant mutation in Pax-6 gene. The mutation leads to impaired migration of anterior midbrain neural crest cells as well as the developmental defects of central nervous system, resulting in lack of eyes and nose, facial cleft and excess maxillary incisor-like structure in the homozygote. Histological observation of serial head sections and whole mount in situ hybridisation of the genes involved in early tooth development were carried out between E12 and E15 wild type and homozygous embryos. The supernumerary incisor-like structure was characterized by histological analysis of twenty E20 homozygous rSey fetuses. In wild type, the initiation of maxillary incisor formation is composed of the fusion of the medial and lateral primary dental placodes (M-PDP and L-PDP) at E13-14 and it develops into bud stage of incisor at E15. In the rSey homozygous fetus, the fusion of PDPs does not take place and they remain separated. Eventually, M-PDP starts invagination and proceeds incisor development. L-PDP also starts invagination, then 25% of them develop incisor-like structures while the rests are arrested at bud stage. The PDPs fusion is concomitant with the fusion of facial primodia, which is interrupted in the homozygote. Whole mount in situ hybridization showed that the genes involved in early tooth development (Fgf-8, Pitx-2, Shh, Bmp-4, Msx-1 and Pax-9) are expressed in wild type maxillary incisor at the initiation stage. This expression pattern is also seen in homozygous M-PDP and L-PDP. These results suggest that Pax-6 mutated in homozygous rSey is not associated to the incidence of supernumerary incisor-like structure via gene controlling but rather via the failure of the fusion of facial primodia to form midface in the homozygote. The failure of the fusion leaves the potentiality to develop tooth of the separated PDPs and allows them to develop incisor as well as the supernumerary incisor-like teeth.
DOI: 10.14457/cu.the.2004.1481
title: Effect of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans on the mechanism of matrix metalloproteinase-2 activation in human periodontal ligament cells

description: Periodontitis is initiated by specific groups of Gram-negative bacteria. Among them, P. gingivalis and A. actinomycetemcomitans have been strongly supported as etiological agents to induce host responses leading to destruction of periodontium. Therefore, the present study attempted to investigate the role of P. gingivalis and A. actinomycetemcomitans product on MMP-2 activation and RANKL-OPG expression in human periodontal ligament (HPDL) cells. The first part of the study was to determine the effect of P. gingivalis and A. actinomycetemcomitans supernatant on MMP-2 activation and its mechanism. Gelatin zymography, RT-PCR and Western analysis were used to detect the activation of MMP-2, expression of MT1-MMP and TIMP-2 mRNA and protein, respectively. The results showed that P. gingivalis and A. actinomycetemcomitans supernatant could activate MMP-2 in HPDL cells. Phenanthroline, an MMP inhibitor, could block the effect of supernatant from both bacteria on MMP-2 activation. In addition, A. actinomycetemcomitans supernatant induced the decreased amount of TIMP-2 protein while P. gingivalis supernatant up-regulated MT1-MMP both at mRNA and protein level. These results suggested that the MMP-2 activation by P. gingivalis and A. actinomycetemcomitans supernatant occurred via MMP-dependent pathway. The second part focuses on the effect of A. actinomycetemcomitans lipopolysaccharide (LPS) on both MMP-2 activation and the expression of RANKL and OPG. The results revealed that A. actinomycetemcomitans LPS could activate MMP-2 but in a different mechanism from the effect of A. actinomycetemcomitans supernatant, since Phenanthroline could not abolish this effect. In addition, serine protease did completely. A. actinomycetemcomitans LPS also up-regulated RANKL expression both at mRNA and protein levels while OPG mRNA level did not change. Additionally, indomethacin and serine protease inhibitor could abrogate this effect. These results suggested the activity of serine protease of A. actinomycetemcomitans LPS induced MMP-2 activation and up-regulated RANKL expression. In conclusion, the present study demonstrated the roles of P. gingivalis and A. actinomycetemcomitans virulences on periodontal tissue destruction represented here by MMP-2 activation and RANKL up-regulation.