bluuebunny/crossref_metadata_2025_split huggingface dataset:
Povidone iodine causes opacification of silicone intraocular lens implants
Authors: Goel Siddharth , Kolli Lajipathi R. , Desai Shrivastav P. , Kumar Ashish , Gauba Vinod , Jayamanne Gerard R. 
Published: July 2008

Abstract.Purpose:  Four cases of silicone intraocular lens (IOL) opacifications presented at a routine cataract service at a UK district general hospital. A systematic investigation was performed to identify and eliminate the causative factor.Methods:  An experiment was set up to determine the role of a chemically induced IOL injury. Silicone IOLs were exposed to the various chemical agents used during cataract surgery. One IOL was not exposed to any chemicals and was used as a control. The samples were then photographed with the same camera settings against the same background in a medical photography studio.Results:  All samples photographed using this technique were clear as the unexposed control IOL, except the IOLs that had come into contact with povidone iodine (PI). Exposure to higher concentrations of PI appears to give a greater opacification and staining – a graded effect.Conclusion:  While the toxic effects of PI on corneal endothelial health is well recognized, as far as the authors are aware no reports exists on the possible harmful effects of PI on IOLs. The results from the current study suggest that exposure of silicone IOLs to even small volumes of 5% PI can lead to IOL opacifying effects. Further studies are needed to determine the toxic effects of PI on all IOL materials. However, based on the results of our study, we strongly recommend extreme caution in the use of PI as prophylaxis against infection at the conclusion of cataract surgery and recommend great care to ensure complete wound closure.
Does exposure to dental education change the perceptions of Nigerian students to dentistry as a profession?
Authors: Sofola O. O. , Uti O. G. , Akpene O. I. 
Published: July 2008

AbstractAim:  To assess any effect of exposure to dental education and training on the perception and acceptance of dentistry by dental students at a Nigerian dental school.Participants and methods:  The study was conducted by means of an anonymous self‐administered questionnaire distributed to second‐, fifth‐ and sixth‐year dental students at the College of Medicine, University of Lagos. Participation was voluntary and 67 students agreed to participate in the study. Majority (51%) were aged between 24 and 27 years. The questionnaire contained questions on demography, preferred choice of course on admission, attempts at change of course, their present perception to dentistry and future dental practice.Result:  Over 90% of them were admitted through the Joint admission and matriculation board and 40 (60%) chose Medicine as their first course choice. Of the 40, 18 had attempted a change of course and eight were still interested in a career change (four were in the fifth year). Most of the change in attitude occurred in fourth year. Sixty (90%) intend to practice dentistry but 38 (63%) of these would like to practice outside Nigeria.Conclusion:  Exposure to dental training appears to improve students’ perception about dental practice but uncertainty about future prospects in Nigeria may lead to brain drain in the dental profession.
Injectable growth/differentiation factor‐5–recombinant human collagen composite induces endochondral ossification via Sry‐related HMG box 9 (Sox9)expression and angiogenesis in murine calvariae
Authors: Kadomatsu H. , Matsuyama T. , Yoshimoto T. , Negishi Y. , Sekiya H. , Yamamoto M. , Izumi Y. 
Published: July 2008

Background and Objective:  The types of collagens available today as biomaterials are purified from animal tissues. A major growing concern, however, is their safety, since there are risks of viral and prion contamination and of unknown and potentially zoonotic infectious diseases. The present study aimed to assess, using immunohistochemistry, the effects of recombinant human growth/differentiation factor‐5 (rhGDF‐5) combined with recombinant human collagen I (rhCI) on bone formation in murine calvariae.Material and Methods:  Composite rhGDF‐5–rhCI or rhCI alone was injected subcutaneously into murine calvariae. After 3, 7 or 14 days, tissues were examined radiologically, histologically and immunohistochemically. The production of vascular endothelial growth factor (VEGF) by primary osteoblasts, periosteal cells and connective tissue fibroblasts isolated enzymatically from neonatal murine calvariae was also assessed.Results:  A protrusion was observed on the calvariae at the site injected with rhGDF‐5/rhCI composite. Its mineral density was shown to be different from that of the existing bone by two‐dimensional microcomputed tomography. Type II collagen‐positive staining was restricted to newly formed tissues. Thus, the newly formed tissues seemed to be bone‐ and cartilage‐like tissues. A number of vessels with positively stained cells for Von Willebrand factor were detected in the newly formed tissues. The rhGDF‐5 enhanced VEGF production in cultured connective tissue fibroblasts. Sry‐related HMG box 9 (Sox9)‐positive cells were detected in the hypertrophic periosteum, and penetrated into the newly formed tissues.Conclusions:  These results suggest that rhCI seems to allow the release of rhGDF‐5 and that rhGDF‐5–rhCI composite induces endochondral ossification via Sox9 expression and angiogenesis in murine calvariae.
Areca nut extract represses migration and differentiation while activating matrix metalloproteinase‐9 of normal gingival epithelial cells
Authors: Tseng Y‐H , Chang K‐W , Liu C‐J , Lin C‐Y , Yang S‐C , Lin S‐C 
Published: July 2008

Background and Objective:  Areca (betel) chewing is associated with an increase in the incidence of periodontal diseases. Aberrations in matrix metalloproteinase (MMP) expression have been reported to be associated with periodontal disease. This study investigated the effects of areca nut extract on MMP activity and the phenotype of human gingival epithelial cells.Material and Methods:  Reverse transcription‐polymerase chain reaction, western blotting and gelatin zymography were used to assay MMPs. Cell viability, mobility and detachment assays were performed to characterize the phenotypic impact. Confocal microscopy was employed to evaluate cell aggregation and the distribution of E‐cadherin and F‐actin.Results:  Treatment of gingival epithelial cells with 10 µg/mL of areca nut extract reduced its cell viability. Treatment with 5 and 10 µg/mL of areca nut extract for 24 h activated MMP‐9 but not MMP‐2 in gingival epithelial cells. This activation could be nuclear factor‐κB dependent and was abrogated by 10 µm curcumin. Areca nut extract also reduced the migration and detachment of gingival epithelial cells. The differentiated cell–cell contact of gingival epithelial cells was markedly impaired by areca nut extract. This was accompanied by a disruption of distribution of E‐cadherin and F‐actin.Conclusion:  The areca nut extract‐mediated activation of MMP‐9 in gingival epithelial cells could signify a potential periodontal pathogenesis in areca chewers. The areca nut extract‐mediated inhibition of cell viability and migration, together with the changed aggregation in gingival epithelial cells, suggests that impairment of the re‐epithelization underlies the process and this, in turn, might exacerbate gingival inflammation.
Tetracycline release from tripolyphosphate–chitosan cross‐linked sponge: a preliminary in vitro study
Authors: Shen E‐C. , Wang C. , Fu E. , Chiang C‐Y. , Chen T‐T. , Nieh S. 
Published: July 2008

Background and Objective:  The aim of this study was to design a tripolyphosphate–chitosan cross‐linked tetracycline‐containing (TPP‐TC) sponge that slowly releases tetracycline, for future periodontal applications.Material and methods:  Chitosan sponge was made by freezing and drying 2.5% chitosan solution. Tripolyphosphate‐chitosan cross‐linked (TPP) sponge was made by immersing the chitosan sponge in tripolyphosphate solution and air drying it. Tetracycline‐containing chitosan (TC) sponge was prepared by freezing and drying a mixture of chitosan and tetracycline. TPP‐TC sponge was made by immersing the TC sponge in tripolyphosphate solution. The weight, thickness and diameter of the four chitosan sponges were recorded. Their surface microstructures were inspected using scanning electron microscopy. The amount of tetracycline released from the sponges was analyzed by spectrophotometry. Antimicrobial activities of the residual sponges were tested against Staphylococcus aureus and Escherichia coli.Results:  The topography of the scaffolds was intact after the addition of tetracycline. However, increased surface irregularities were noted. In sponges with tripolyphosphate, intensified surface folding was observed. The weight of the sponges increased after tripolyphosphate and tetracycline were added, but their thicknesses and diameters decreased after cross‐linking. Tetracycline was detected in the solution containing TPP‐TC sponges until day 11. On day 7, the tetracycline released from TC sponges was less than that released from TPP‐TC sponges. Bacterial growth was inhibited by sponges containing tetracycline. The inhibitory effect of the TPP‐TC sponges was detectable until day 11.Conclusion:  Our data showed that TPP‐TC sponge was suitable as a slow‐release device for tetracycline and that it maintained antimicrobial effects against the bacteria tested for up to 11 d.
Fractal analysis of dental radiographs to detect periodontitis‐induced trabecular changes
Authors: Updike Sophia Xiang , Nowzari Hessam 
Published: July 2008

Background and Objective:  The aim was to evaluate fractal analysis as a tool to quantitatively measure the impact of periodontal disease on surrounding bone. The diagnosis of periodontitis is based on information obtained from clinical and radiographic examinations. The current standard use of dental radiographs is visual inspection, often with no quantitative analysis. Fractal analysis can be used to examine trabecular bone patterns among periodontal patients.Material and Methods:  Patients (n = 108) from the University of Southern California School of Dentistry were classified into three groups: healthy, moderate and severe periodontitis. A region of interest was selected from periapical radiographs. Image processing was applied to correct for lighting irregularity, and the box‐counting method was used to calculate a fractal dimension. ANOVA and ANCOVA were used to measure fractal dimension differences between all groups.Results:  According to the statistical tests, significant differences in average fractal dimensions were measured between healthy and moderate periodontitis groups (p < 0.01) and between healthy and severe periodontitis groups (p < 0.001). Higher fractal dimensions were measured in healthy periodontal patients.Conclusion:  Fractal analysis evidenced significant differences between patients affected and not affected by periodontitis. The box‐counting method quantitatively describes the severity of bone disease and can be used to improve current diagnostic techniques.
Putative stem cells in regenerating human periodontium
Authors: Lin N‐H. , Menicanin D. , Mrozik K. , Gronthos S. , Bartold P. M. 
Published: July 2008

Background and Objective:  Human postnatal stem cells have been identified in periodontal ligament, with the potential to regenerate the periodontium in vivo. However, it is unclear if periodontal ligament stem cells are present in regenerating periodontal tissues. The aim of this study was to identify and localize putative stem cells in block biopsies and explant cultures of regenerating human periodontal tissues.Material and Methods:  Guided tissue regeneration was carried out on the molars of three human volunteers. After 6 wk, the teeth with the surrounding regenerating tissues and bone were surgically removed and processed for immunohistochemistry. The mesenchymal stem cell‐associated markers STRO‐1, CD146 and CD44 were used to identify putative stem cells. Cell cultures established from regenerating tissue explants were analysed by flow cytometry to assess the expression of these markers. Mineralization, calcium concentration and adipogenic potential of regenerating tissue cells were assessed and compared with periodontal ligament stem cells, bone marrow stromal stem cells and gingival fibroblasts.Results:  STRO‐1+, CD44+ and CD146+ cells were identified in the regenerating tissues. They were found mainly in the paravascular and extravascular regions. Flow cytometry revealed that cultured regenerating tissue cells expressed all three mesenchymal stem cell associated markers. The regenerating tissue cells were able to form mineral deposits and lipid‐containing adipocytes. However, the level of mineralization in these cells was lower than that of periodontal ligament stem cells and bone marrow stromal stem cells.Conclusion:  Cells with characteristics of putative mesenchymal stem cells were found in regenerating periodontal tissues, implying their involvement in periodontal regeneration.
Human periodontal ligament: a niche of neural crest stem cells
Authors: Coura G. S. , Garcez R. C. , De Aguiar C. B. N. Mendes , Alvarez‐Silva M. , Magini R. S. , Trentin A. G. 
Published: July 2008

Background and Objective:  The periodontal ligament is a specialized connective tissue, derived from dental follicle and originated from neural crest cells. Recently it has been suggested, based on animal models, that periodontal ligament could be a niche for neural crest stem cells. However, there is still little knowledge on this subject. The identification of neural crest adult stem cells has received much attention based on its potential in tissue regeneration. The objective of the present work was to verify the human periodontal ligament as a niche for neural crest stem cells.Material and Methods:  Cells from human periodontal ligament were isolated from 10 teeth of seven individuals (periodontal ligament pool group) and also from four teeth of one individual (periodontal ligament single group), after enzymatic digestion. The cells were cultured in specific inductive medium. Analyses of protein and gene expression were performed through immunocytochemistry and reverse transcription–polymerase chain reaction techniques, respectively.Results:  Mesodermal phenotypes (adipogeneic, osteogenic and myofibroblastic) were identified after culture in inductive medium. Immunocytochemistry analyses showed the presence of the nestin marker of neural stem cells and also markers of undifferentiated neural crest cells (HNK1, p75). When cultured in inductive medium that allowed neural differentiation, the cells showed markers for β‐tubulin III, neurofilament M, peripherin, microtubule‐associated protein 2 and protein zero. The results were similar between the two study groups (the periodontal ligament pool group and the periodontal ligament single group).Conclusion:  This research provides evidence that human periodontal ligament, in addition to its mesodermal derivatives, produces neural crest‐like cells. Such features suggest a recapitulation of their embryonic state. The human periodontal ligament revealed itself as a viable alternative source for possible primitive precursors to be used in stem‐cell therapies.
Insulin‐like growth factor binding protein‐5 enhances the migration and differentiation of gingival epithelial cells
Authors: Hung P.‐S. , Kao S.‐Y. , Liu C.‐J. , Tu H.‐F. , Wu C.‐H. , Lin S.‐C. 
Published: July 2008

Background and Objective:  The objective was to define the roles of insulin‐like growth factor binding protein‐5 (IGFBP‐5) in gingival epithelial cells (GEC). Human IGFBP‐5 is expressed in many cell types and has diverse biological functions. It stimulates the growth of bone cells and is associated with the impedance of gingival fibroblast apoptosis. In gingival epithelium, IGFBP‐5 is expressed in the cells of the differentiated stratum spinosum layer.Material and Methods:  Recombinant IGFBP‐5 protein treatment and knockdown of IGFBP‐5 expression using a lentivirus‐delivered short hairpin RNA was carried out in human GEC. Proliferation, apoptosis, anoikis, migration, differentiation and gene expression in GEC were analyzed and molecular images were obtained.Results:  The IGFBP‐5 had no effect on proliferation, but it slightly suppressed apoptosis and anoikis of GEC. It also induced GEC migration and upregulated the expression of involucrin, transglutaminase‐1, keratin and focal adhesion kinase. The IGFBP‐5 induced migration partly via an insulin‐like growth factor‐independent mechanism. The knockdown of IGFBP‐5 downregulated the expression of involucrin, transglutaminase‐1 and focal adhesion kinase.Conclusion:  Expression of IGFBP‐5 in GEC is associated with anti‐apoptosis, migration and differentiation of GEC. These phenotypic effects may be associated with focal adhesion kinase and are advantageous for re‐epithelization of GEC and the maintenance of gingival health.
Periodontal tissue engineering by transplantation of multilayered sheets of phenotypically modified gingival fibroblasts
Authors: Nakajima K. , Abe T. , Tanaka M. , Hara Y. 
Published: July 2008

Background and Objective:  In periodontal tissue engineering, the sourcing of most of the relevant cells is limited by poor accessibility, whereas the use of readily available gingival fibroblasts is hampered because of their inhibitory effects on bone formation. To address the latter drawback, we developed a new graft composed of fibronectin (FN) matrix‐based multilayered cell sheets of human gingival fibroblasts modified to express alkaline phosphatase (ALP). This study was undertaken to investigate the effects of this graft, called the FN‐ALP transplant, on the healing of periodontal defects in a rat model.Material and Methods:  The FN‐ALP transplants were grafted into periodontal fenestration bone defects in immunosuppressed rats. The process of periodontal healing was examined by histology, histomorphometry and immunohistochemistry. Grafted cells were tracked by immunostaining with human‐specific antibodies. Control groups included non‐transplanted empty defects and defects to which cell sheets without ALP induction had been grafted.Results:  After implantation, the FN‐ALP transplants healed alveolar bone defects by intramembranous ossification, with formation of cementum and periodontal ligament. Moreover, FN‐ALP transplants increased new bone formation, by endochondral ossification, on the mandibular cortex adjacent to the defect. Grafted fibroblasts were located near host osteoblasts and chondrocyte precursor cells early in the ossification process but were undetectable on and in newly formed bone and cartilage.Conclusion:  These results indicate that the FN‐ALP transplants support alveolar bone regeneration within the defect and augment bone formation outside the defect through the recruitment of host osteo/chondrogenic cells, suggesting their potential for periodontal tissue engineering applications.
Variability in the response of human dendritic cells stimulated with Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans
Authors: Vernal R. , Leon R. , Herrera D. , Garcia‐Sanz J. A. , Silva A. , Sanz M. 
Published: July 2008

Background and Objective:  Dendritic cells are able to prime and polarize naïve T cells towards either a T helper 1 or a T helper 2 response, depending on the antigen type and concentration, the costimulatory signals and the local cytokine millieu. In this investigation, we analyzed the response of human dendritic cells to stimulation with different concentrations of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans.Material and Methods:  Using different concentrations of P. gingivalis ATCC 33277 and A. actinomycetemcomitans ATCC 33384, we determined the expression of the maturation markers CD80 and CD86 from purified human dendritic cells by flow cytometry. We also evaluated the mRNA expression levels for the cytokines interleukin‐1β, interleukin‐2, interleukin‐5, interleukin‐6, interleukin‐10, interleukin‐12, interleukin‐13, interferon‐γ, tumor necrosis factor‐α and tumor necrosis factor‐β by quantitative real‐time reverse transcription–polymerase chain reaction.Results:  Both P. gingivalis and A. actinomycetemcomitans led to dendritic cell maturation, but the expression of CD80 was higher when the dendritic cells were stimulated with A. actinomycetemcomitans. Although both pathogens induced a T helper 1 pattern of cytokine expression, A. actinomycetemcomitans‐stimulated dendritic cells expressed interleukin‐1β, interleukin‐12, interferon‐γ, tumor necrosis factor‐α and tumor necrosis factor‐β at lower bacterial concentrations than P. gingivalis. While 106 bacteria/mL of P. gingivalis or 104 bacteria/mL of A. actinomycetemcomitans induced expression of interleukin‐12p40, the expression of other cytokines required 10 to 100‐fold higher concentrations of bacteria.Conclusion:  These results demonstrate that A. actinomycetemcomitans is a more potent immunogen than P. gingivalis because, at least in vitro, it induces stronger differentiation and activation of dendritic cells. In addition, our data also show that for a given strain, the bacterial load determines the pattern of cytokines that are expressed.
A novel selective medium for isolation of Aggregatibacter (Actinobacillus) actinomycetemcomitans
Authors: Tsuzukibashi O , Takada K , Saito M , Kimura C , Yoshikawa T , Makimura M , Hirasawa M 
Published: July 2008

Background and Objective:  Conventional selective media have been used for the selection of Aggregatibacter (Actinobacillus) actinomycetemcomitans in clinical samples. The proportion of A. actinomycetemcomitans grown on the selective media in vitro may not reflect the true counts in vivo because of the low selectivity. A novel selective medium, designated AASM, was developed for the isolation of A. actinomycetemcomitans.Material and Methods:  AASM was prepared by adding of 200 μg/mL of vancomycin and 10 U/mL of bacitracin to AAGM, which contains dextrose, sodium bicarbonate, trypticase soy, yeast extract and agar. Clinical efficacy was evaluated by the recovery, on AASM, of A. actinomycetemcomitans from subgingival samples of 44 periodontally healthy subjects and 76 patients with chronic periodontitis.Results:  All serotypes (a–f) of A. actinomycetemcomitans strains grew well, and the average growth recovery of A. actinomycetemcomitans on AASM medium was 94.4% (80.0–109.7%) of that on AAGM. The exclusive rate of other bacteria was 99.9% in clinical samples cultured on AASM. A. actinomycetemcomitans was not detected in periodontally healthy persons but was detected in 25 (32.9%) patients with chronic periodontitis. The predominant serotype was c, detected in 11 subjects.Conclusion:  The new selective medium, AASM, was highly selective for A. actinomycetemcomitans, eliminated possible false‐positive results and was useful for the isolation of A. actinomycetemcomitans from clinical samples.