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This paper concerns the universality of the two-layer neural network with the k -rectified linear unit activation function with k = 1 , 2 , ... with a suitable norm without any restriction on the shape of the domain in the real line. This type of result is called global universality, which extends the previous result for k = 1 by the present authors. This paper covers k -sigmoidal functions as an application of the fundamental result on k -rectified linear unit functions. [ABSTRACT FROM AUTHOR]

In the present study, we investigate a universality of neural networks, which concerns a density of the set of two-layer neural networks in function spaces. There are many works that handle the convergence over compact sets. In the present paper, we consider a global convergence by introducing a norm suitably, so that our results will be uniform over any compact set. [ABSTRACT FROM AUTHOR]

Aims/Introduction To explore the relationships between periodontitis and microvascular complications as well as glycemic control in type 2 diabetes patients. Materials and Methods This multicenter, hospital-based, cross-sectional study included 620 patients with type 2 diabetes. We compared the prevalence and severity of periodontitis between patients with ≥1 microvascular complication and those without microvascular complications. We also compared the prevalence and severity of periodontitis among patients with different degrees of glycemic control. Results After adjusting for confounding factors, multiple logistic regression analysis showed that the severity of periodontitis was significantly associated with the number of microvascular complications (odds ratio 1.3, 95% confidence interval 1.1-1.6), glycated hemoglobin ≥8.0% (64 mmol/mol; odds ratio 1.6; 95% confidence interval 1.1-2.3), and older age (≥50 years; odds ratio 1.7; 95% confidence interval 1.1-2.6). However, the prevalence of periodontitis was not significantly associated with the number of microvascular complications, but was associated with male sex, high glycated hemoglobin (≥8.0% [64 mmol/mol]), older age (≥40 years), longer duration of diabetes (≥15 years) and fewer teeth (≤25). Furthermore, propensity score matching for age, sex, diabetes duration and glycated hemoglobin showed that the incidence of severe periodontitis was significantly higher among patients with microvascular complications than among those without microvascular complications ( P < 0.05). Conclusions The number of microvascular complications is a risk factor for more severe periodontitis in patients with type 2 diabetes, whereas poor glycemic control is a risk factor for increased prevalence and severity of periodontitis. [ABSTRACT FROM AUTHOR]

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2, neodymium-doped yttrium-aluminium-garnet (Nd: YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er: YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr: YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri-implant treatment, focusing on postoperative wound healing of periodontal and peri-implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports. [ABSTRACT FROM AUTHOR]

Background: Toll-like receptors (TLRs) play pivotal roles in host immune responses and have been suggested to be involved in the development of many infectious diseases. In this study, the mRNA expression levels of TLR2, TLR4, and TLR9 and their relationship with periodontopathic bacteria in periodontal tissue are examined. Furthermore, the mechanism of TLR induction by Porphyromonas gingivalis is investigated in human gingival fibroblasts (HGFs). Methods: Gingival tissue and subgingival plaque samples were collected from 19 patients with chronic periodontitis (CP) and 16 control individuals without periodontitis. Gene expression levels in the tissues and in HGFs were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The numbers of periodontopathic bacteria were determined by quantitative real-time PCR. Results: The expression levels of TLR2 and TLR9 were significantly higher in the tissues of patients with CP compared to the tissues of control individuals. The mRNA levels of TLR2 and TLR9, but not TLR4, were positively correlated with the number of P. gingivalis in subgingival plaque. P. gingivalis sonicated extract, P. gingivalis lipopolysaccharide, P. gingivalis DNA, and tumor necrosis factor-αTNF could significantly upregulate the mRNA expression of TLR2 in HGFs. Furthermore, P. gingivalis-mediated TLR2 expression was suppressed by TNF-α antibody. Conclusions: This study suggests that P. gingivalis infection induces TLR2 and TLR9 upregulation patients with CP. P. gingivalis-induced TLR2 expression in HGFs is partially dependent on TNF-α and may lead to sensitization of HGFs to bacterial components encountered in the periodontal microenvironment. [ABSTRACT FROM AUTHOR]

The article offers information on several technologies used in periodontal tissue engineering. It states that bone-graft materials, such as bioceramics, are used in periodontal surgery because the grafts increase bone and clinical attachment levels. It adds that the surgical procedure known as guided tissue regeneration is performed to restore the supporting periodontal tissues of a tooth. Furthermore, Emdogain® is used to increase the supporting areas of the root of a transplanted tooth.

Aim: Periodontal ligament (PDL) is a reliable cell source for periodontal regeneration. In this study, an optimal protocol for the extraction, expansion, and characterization of human PDL (hPDL) cells was examined for clinical trials. Materials and Methods: hPDL tissues were obtained from 41 surgically extracted teeth and digested with enzymes. Human adipose-derived stem cells (hADSCs), bone marrow-derived mesenchymal stem cells (hBMMSCs), and gingival fibroblasts (hGFs) were used for comparison. For each sample, the proliferative capacity, colony-forming ability, alkaline phosphatase activity, differentiation ability, the cell surface antigens, gene expression, and regenerative potential were examined. Results: hPDL cells were more successfully extracted with collagenase/dispase [29/30 (96.7%)] than with trypsin/EDTA [8/11 (72.7%)], and exhibited osteogenic potential both in vitro and in vivo. The proliferation of hPDL cells was rapid at a low cell density. hPDL cells frequently differentiated into cementoblastic/osteoblastic lineage (~60%). In contrast, their adipogenic and chondrogenic potentials were lower than those of hADSCs and hBMMSCs. Some genes (NCAM1, S100A4, and periostin) were preferentially expressed in hPDL cells compared with those of hBMMSCs and hGFs. Immunohistochemical studies revealed the expressions of S100A4 and periostin in hPDL tissue. Conclusion: A protocol for the successful cultivation and validation of hPDL cells is proposed for clinical setting [ABSTRACT FROM AUTHOR]

Patients with acquired cystic disease of the kidney (ACDK) were followed longitudinally over an average of 21.7 ± 5.4 years to determine the natural history of the disease; that is, how big the kidneys become, when the kidney size reaches a plateau, and when the size regresses. Twenty-seven male and 20 female patients with chronic glomerulonephritis treated at our hospital were investigated. CT scans were performed once a year and kidney volume was measured. Two different quadratic curves with a node of 5.2 years for males and 2.5 years for females after the start of hemodialysis were fitted to log-transformed kidney volume to the duration of hemodialysis using a linear mixed model. The maximum kidney volume in male patients was obtained 21.1 years after the start of hemodialysis using this model. Peak values of kidney volume were demonstrated in 19 of 26 cases during the observation period. The median peak value (interquartile range) of bilateral kidney volumes was 274 (165–849) mL/1.73 m2 occurring 19.1 ± 4.5 years after the start of dialysis. In one male patient who had undergone nephrectomy due to renal cell carcinoma and in two of the remaining 26 male patients, the maximum kidney volume of 782 (residual kidney), 1151, and 1129 mL regressed to 428, 616, and 847 mL (reduction rate: 45.3, 46.5, and 25.0%) at 20.6, 25.4, and 23.1 years after the start of hemodialysis, respectively. Kidney enlargement due to ACDK reached a plateau after 21.1 years of hemodialysis in the male patients. Partial regression of severe ACDK may occur naturally after long-term hemodialysis without renal transplantation. [ABSTRACT FROM AUTHOR]

The article examines the efficiency of the cell sheet engineering method in periodontal regeneration. It states that tissue engineering is a method that uses a combination of cells, signaling molecules and scaffolds to improve or replace biological functions. It notes that the said technique enables clinicians to transplant cell sheets with their conserved structures. It adds that the said method can be a practical alternative in future regerative medicine.

The article examines the efficiency of antimicrobial photodynamic method in treating periodontal and per-implant diseases. It states that the said method is essential in eliminating periodontal pathogens through the use of the photodynamic method, which combines the application of non-toxic chemical agent with low-level light energy. It notes that the main components of a photodynamic therapy includes visible harmless light, a nontoxic photosensitizer, and oxygen.

Aim: Anti-cardiolipin (CL) antibodies can be induced in Buerger disease (BD), an inflammatory occlusive disorder affecting peripheral blood vessels, in response to bacteria bearing homology to the TLRVYK peptide of a phospholipid-binding plasma protein β-2-glycoprotein I. TLRVYK homologies are present in Porphyromonas gingivalis (TLRIYT) and Treponema denticola (TLALYK). This study investigated the association between periodontal infection and anti-CL antibodies in BD patients. Material and Methods: Periodontal conditions were examined in 19 BD patients and 25 systemically healthy control subjects. All subjects were heavy smokers. Serum anti-CL, anti-TLRVYK, anti-TLRIYT, and anti-TLALYK antibodies were assessed using the enzyme-linked immunosorbent assay. Results: BD patients had a significantly higher prevalence of periodontitis, more severe periodontal destruction and increased titres of serum anti-CL, anti-TLRVYK, anti-TLRIYT, and anti-TLALYK antibodies compared with healthy subjects. The levels of anti-CL antibodies positively correlated with those of the three anti-peptide antibodies. Anti-CL antibody titres were significantly associated with the percentage of sites with clinical attachment level ⩾4 mm in BD patients. Conclusion: Elevated anti-CL antibody levels were associated with periodontal destruction in BD patients. Periodontopathic bacteria may serve as exogenous antigens that stimulate the anti-CL antibody production through molecular mimicry between the bacterial peptides and a host plasma protein. [ABSTRACT FROM AUTHOR]

The article focuses on the application of the laser technology in periodontics. Reducing the patient's physical and mental stress is the primary advantage of a laser when treating dental caries. Laser irradiation can also create strong ablation, hemostasis, and bactericidal effects on the human body. However, high financial cost of a laser apparatus is the primary disadvantage of such application.

Background: The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is reportedly useful for periodontal therapy. However, the potential thermal damage that Er:YAG laser irradiation can produce on bone tissue has not been fully clarified. The purpose of this study was to histologically examine the effects of the Er:YAG laser on bone tissue and subsequent wound healing compared to electrosurgery in a long-term study. Methods: Calvarial bone from 30 rats was exposed to contact and non-contact Er:YAG laser irradiation (115 mJ/pulse, 10 Hz) without water coolant, or electrode contact. The treated surfaces were analyzed by scanning electron microscopy (SEM), and the healing process was histologically observed until 12 months post-surgery. Results: Contact irradiation resulted in substantial bone ablation, whereas non-contact irradiation produced slight tissue removal. Histologic and SEM analyses of the lased surface showed no severe thermal damage, except for the production of a superficially affected layer with a microstructured surface. The layer did not inhibit new bone formation, and the ablated defect was repaired uneventfully. Although the thickness of the layer gradually decreased, it generally remained in the cortical bone through the observation period. Electrosurgery produced a large area of thermal necrosis without ablation, and the damaged area was not replaced with new bone. Conclusions: Unlike electrosurgery, Er:YAG laser irradiation without water coolant easily ablated bone tissue, and thermal alteration in the treated surface was minimal. The superficially affected layer did not interfere with the ensuing bone healing, resulting in favorable repair of the defect. [ABSTRACT FROM AUTHOR]

Aim: The primary goal of periodontal treatment is regeneration of the periodontium. Current theories suggest that the periodontal ligament (PDL) cells have the capacity to participate in restoring connective and mineralized tissues, when appropriately triggered. We evaluated whether human PDL cell sheets could reconstruct periodontal tissue. Material and Methods: To obtain the cell sheet, human PDL cells were cultured on temperature-responsive culture dishes with or without osteogenic differentiation medium. The cell sheets were transplanted on periodontal fenestration defects of immunodeficient rats. Forty rats were divided in two groups: in one group, cell sheets cultured with control medium were transplanted and in the other, cell sheets cultured with osteogenic differentiation medium were transplanted. The defects were analysed histologically and histomorphologically after healing. Results: Most of the experimental group exhibited a new cementum-like layer and new attachment of collagen fibres to the layer. Histomorphological analyses indicated significant periodontal regeneration. The control group revealed dense extracellular matrix and fibre formation, but an obvious cementum layer was not observed. Conclusions: Transplanted PDL cell sheets cultured with osteogenic differentiation medium induced periodontal regeneration containing an obvious cementum layer and Sharpey's fibres. Thus, the method could be feasible as a new therapeutic approach for periodontal regeneration. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to compare the effect of single-visit full-mouth mechanical debridement (FMD) and quadrant-wise mechanical debridement (QMD) on the levels of serum interleukin (IL)-6, C-reactive protein (CRP) and soluble thrombomodulin. Material and Methods: Thirty-six subjects with chronic periodontitis were randomly allocated to three groups: undergoing QMD, single-visit FMD with povidone iodine or with water. Serum IL-6 and soluble thrombomodulin were measured by enzyme-linked immunosorbent assay, and serum CRP was measured by the latex-enhanced nephelometric method. Results: Serum IL-6 level increased significantly immediately after debridement in all the three groups, with this increase being greatest in the full-mouth groups. However, the increase in the full-mouth groups was not significantly higher than that of quadrant-wise group. In the quadrant-wise group, serum IL-6 level decreased significantly 1 month after debridement compared with baseline. Serum-soluble thrombomodulin decreased significantly in the full-mouth groups but not in the quadrant-wise group. Changes in CRP level were not significant at baseline or after debridement in all the three groups. Conclusions: FMD increased serum IL-6 and reduced serum-soluble thrombomodulin to a greater extent than QMD, suggesting that the former technique has stronger transient effects on systemic vascular endothelial functions than the latter. [ABSTRACT FROM AUTHOR]

Renal transplantation (RTx) from marginal donors has been performed in most Japanese transplant centers because of severe donor organ shortage. RTx using marginal donors with prolonged warm ischemic time (WIT) has sometimes resulted in primary non-function (PNF). Among 53 cadaveric RTx performed at Kanazawa Medical University between October 1986 and May 2006, five cases using non-heart-beating donors resulted in PNF. In these five patients, histologic examination of one h RBx (graft biopsy one h after revascularization) revealed extensive congestion in glomerular and peritubular capillaries. Glomerular subendothelial swelling and mesangiolysis were also detected, and electron microscopic examination showed widening of the subendothelial spaces of glomerular capillaries. Such findings of endothelial damage were not detected in the other 48 cases without PNF. In contrast, no distinct abnormalities other than acute tubular necrosis were found in zero h RBx (graft biopsy before implantation) obtained from three patients with PNF. Prolonged WIT was the prominent feature of the five patients with PNF, and multiple logistic analysis showed that prolonged WIT was a significant risk factor for the development of endothelial damage on reperfusion. Paired allografts from the same donors of these five cases also ended in PNF. It is conceivable that the endothelial damage was caused by ischemia–reperfusion injury and extensive congestion followed as a result of endothelial injury. Ischemia–reperfusion injury is the leading cause of PNF in RTx using donors with prolonged WIT. Guidelines to assess the viability of marginal grafts should be established in the future to prevent transplantation of non-functioning grafts. [ABSTRACT FROM AUTHOR]

Background: The use of the erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser in periodontal therapy has been the focus of much research. Recombinant human platelet-derived growth factor-BB (rhPDGF-BB) is suggested as a potent stimulator and strong mitogen for human periodontal ligament cells. The present study tested the direct effects of Er:YAG laser irradiation, alone or with rhPDGF-BB application, on the biocompatibility of periodontally diseased roots through fibroblast attachment and proliferation.Methods: The study examined five healthy and 15 periodontally involved teeth, prepared from proximal surfaces, which were divided randomly into four groups (10 specimens each): group 1: healthy; group 2: untreated diseased; group 3: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz); and group 4: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz) plus rhPDGF-BB application (50 ng/ml). Three subgroups per group (three specimens each) were incubated for three periods (1, 3, or 7 days). The remaining specimen was used to determine surface topography. Fibroblasts were pooled on root specimens and incubated. Results were evaluated using scanning electron microscopy. Repeated cell counts were performed within a representative standard area.Results: Using paired t tests, all experimental groups (except group 2 diseased) showed statistically significant differences between 1- and 3-day and between 1- and 7-day incubation periods, but not between 3- and 7-day incubation periods. Using analysis of variance, the intergroup comparison showed significant differences favoring group 1 over groups 2 and 3 and group 4 over group 2 at the 1-day incubation period; group 1 was favored over groups 2, 3, and 4 and groups 3 and 4 were favored over group 2 at the 3- and 7-day incubation periods. Comparable effects were shown between groups 3 and 4 for all incubation periods and between groups 2 and 3 and groups 1 and 4 for the 1-day incubation.Conclusions: Er:YAG laser used alone or in combination with rhPDGF-BB application may offer a promising periodontal therapy for conditioning root surfaces, although the combined application seemed to be slightly more effective. However, testing laser use in intervals and with parameters <60 mJ/pulse and 10 Hz is required to verify the minimum threshold values necessary to obtain complete root debridement and clarify optimal conditions for fibroblast cell attachment and growth. Further studies are needed to determine ideal parameters for creating the best environment for successful periodontal treatment. [ABSTRACT FROM AUTHOR]

The article discusses the roles of cyclooxygenase-2, prostaglandin E2 and its receptors in periodontal disease. Details of prostanoid synthesis, effects of prostaglandin E2 on immune and inflammatory responses on bone metabolism and periodontal tissue regeneration are mentioned. Effects of specific cyclooxygenase-2 inhibitors on the progression of periodontal disease are provided with charts and diagrams.

The article discusses various reports published within the issue on host responses in periodontitis.

Background: Periodontal ligament (PDL) cells possess osteoblast-like properties and play key roles in periodontal regeneration. Previously, we have reported that ascorbic acid promotes the osteoblastic differentiation of PDL cells by modulating the type I collagen-integrin interaction. However, the signaling pathway activated following collagen-integrin interaction is still unclear. In this study, we examined the involvement of extracellular signal-regulated kinase (ERK)1/2 in the expression of osteoblastic marker genes such as the osteoblast-specific transcriptional factor runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and osteocalcin (OCN) in PDL cells.Methods: PDL cells were cultured on a conventional or type I collagen-coated dish in the presence or absence of ascorbic acid and examined for ALP activity and osteoblastic marker genes. For detection of ERK1/2, cells were plated on a petri (non-adhesive) dish or type I collagen-coated dish, and Western blot analysis was performed. The effect of the ERK1/2 inhibitor on osteoblastic marker gene expression was examined.Results: Ascorbic acid increased gene expression of Runx2, ALP, and OCN. A combination of ascorbic acid and type I collagen remarkably upregulated Runx2, ALP, and OCN gene expression and ALP activity. Western blot analysis revealed an increased level of ERK1/2 phosphorylation in cells plated on type I collagen. An ERK1/2 inhibitor suppressed ascorbic acid-induced ALP and OCN gene expression, whereas Runx2 was not affected in PDL cells.Conclusion: These results indicate that ERK1/2 is involved in ascorbic acid-induced osteoblastic differentiation during PDL cell attachment to type I collagen. [ABSTRACT FROM AUTHOR]

Background: Periodontal ligament (PDL) cells possess osteoblast-like properties and play key roles in periodontal regeneration. Previously, we have reported that ascorbic acid promotes the osteoblastic differentiation of PDL cells by modulating the type I collagen--integrin interaction. However, the signaling pathway activated following collagen-integrin interaction is still unclear. In this study, we examined the involvement of extracellular signal-regulated kinase (ERK)½ in the expression of osteoblastic marker genes such as the osteoblast specific transcriptional factor runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and osteocalcin (OCN) in PDL cells. Methods: PDL cells were cultured on a conventional or type I collagen-coated dish in the presence or absence of ascorbic acid and examined for ALP activity and osteoblastic marker genes. For detection of ERK½, cells were plated on a petri (non-adhesive) dish or type I collagen coated dish, and Western blot analysis was performed, The effect of the ERK½ inhibitor on osteoblastic marker gene expression was examined. Results: Ascorbic acid increased gene expression of Runx2, ALP, and OCN. A combination of ascorbic acid and type 1 collagen remarkably upregulated Runx2, ALP, and OCN gene expression and ALP activity. Western blot analysis revealed an increased level of ERK½ phosphorylagon in cells plated on type I collagen. An ERK½ inhibitor suppressed ascorbic acid induced ALP and OCN gene expression, whereas Runx2 was not affected in PDL cells. Conclusion: These results indicate that ERK½ is involved in ascorbic acid-induced osteoblastic differentiation during PDL cell attachment to type I collagen. J Periodontol 2007;78: 328-334. [ABSTRACT FROM AUTHOR]

The major non-collagenous proteins in dentin have extensive post-translational modifications (PTMs) that appear to be odontoblast-specific, so expression of recombinant dentin proteins in other cell types does not achieve the in vivo pattern of PTMs. We established cell lines from developing porcine dental papillae and used them to express recombinant dentin sialoprotein (DSP) and dentin matrix protein-1 (DMP1). Pulp cells were immortalized with pSV3-neo and clonally selected. Cell lines were characterized by reverse transcruption–polymerase chain reaction (RT–PCR) and assayed for alkaline phosphatase activity and mineralized nodule formation. One of the five cell lines (P4-2) exhibited an odontoblastic phenotype, as determined by expression of tooth-specific markers, response to cytokines, and ability to form mineralized nodules. DSP and DMP1 expression constructs were transiently transfected into various cell lines. DSP, expressed by P4-2 cells, contained chondroitin 6-sulfate, which is a defining modification of the DSP proteoglycan. DMP1 was secreted and cleaved by proteases, even in human kidney 293 cells, which normally do not express DMP1, demonstrating susceptibility to non-specific proteolysis. Both recombinant proteins enhanced P4-2 cell attachment in a dose-dependent manner. We conclude that we have immortalized porcine odontoblast-like cells which express recombinant dentin extracellular matrix components with post-translational modifications that closely resemble those produced in vivo. [ABSTRACT FROM AUTHOR]

The article discuses the roles of receptor activator of nuclear factor-kB ligand (RANKL) and osteoprotegerin in periodontology. The article details some topics of periodontal health and disease such as the immune system in the gingival tissue, diagnostic value of antibacterial antibodies in periodontitis, vaccine against periodontitis, osteoimmunology, expression and role of RANKL in some diseases. The article concludes with a note on further research in molecular mechanisms in periodontology.

Introduction: The aim of this study was to compare serum antibody responses to periodontal pathogens after single-visit full-mouth ultrasonic debridement and quadrant-wise therapy. Material and Methods: Thirty-six subjects with chronic periodontitis were randomized into three groups: quadrant-wise debridement in four visits, one-visit full-mouth debridement with water and with povidone iodine. Blood samples were collected before and immediately after treatment and 1, 3 and 6 months post-therapy. Serum antibody titres and avidity to Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Treponema denticola were determined by enzyme-linked immunosorbent assay (ELISA) and thiocyanate ELISA, respectively. Results: IgG titres to P. gingivalis significantly decreased at 1, 3 and 6 months in full-mouth debridement with water group, while significant reductions were seen only at 3 and 6 months after quadrant-wise debridement. Both full-mouth groups showed significant reduction in IgG titres to A. actinomycetemcomitans at 3 and 6 months. Significant increases in antibody avidity to P. gingivalis and A. actinomycetemcomitans were noted 3 months following full-mouth debridement with povidone. Conclusion: Both full-mouth and quadrant treatments generally resulted in a decrease in antibody titres and increase in antibody avidity. Full-mouth debridement induced an earlier reduction of IgG titre to P. gingivalis and A. actinomycetemcomitans, than quadrant-wise therapy. [ABSTRACT FROM AUTHOR]

Background: An earlier study showed that an injectable calcium phosphate cement (CPC) served as a stable scaffold for bone formation and promoted histocompatible healing of periodontal tissue in dogs. In this study, we evaluated the influence of CPC on regeneration of periodontal defects with experimental periodontitis in dogs. Methods: Experimental periodontitis was induced by placing stainless-steel mesh on the mesial side of maxillary ca nines in six adult, healthy beagle dogs. Subsequently, intrabony defects were resized so as to be standard, and CPC was injected in the experimental bone defects. Non-grafted defects on the contralateral side served as controls. Twelve weeks after surgery, the animals were sacrificed and histologic specimens were prepared. Periodontal tissue healing was evaluated histologically and histometrically. Results: Healing of periodontal tissues, in terms of bone and cementum formation, was consistently observed in the CPC-applied sites. CPC was partly replaced by new bone. New cementum and periodontal ligament dike tissue were observed between CPC and the root surface. New bone (P<0.05), new cementum (P<0.01), and new connective tissue attachment and adhesion (P<0.05) were significantly enhanced in the experimental sites. Conclusion: Calcium phosphate cement provides stable wound healing and enhanced periodontal regeneration in periodontal defects in dogs with experimental periodontitis. [ABSTRACT FROM AUTHOR]

Background: The aim of this randomized controlled clinical trial was to determine the effects of single-visit full-mouth ultrasonic debridement versus quadrant- wise therapy. Material and Methods: Thirty-six subjects with chronic periodontitis, were randomly allocated to three groups - quadrant-wise ultrasonic debridement, single- visit full-mouth ultrasonic debridement with povidone iodine and single-visit full- mouth ultrasonic debridement with water. Whole-mouth plaque, bleeding on probing (BOP), pocket depth and attachment level were recorded before treatment and 1, 3 and 6 months post-treatment. Plaque and saliva samples were collected for microbiological analysis. Results: After treatment, all groups showed significant improvement in clinical parameters. Full-mouth treatments resulted in similar improvements in full-mouth mean plaque percentage, probing pocket depth and probing attachment level as conventional therapy. When data were analysed based on pocket depth and tooth type, there was no difference between groups in probing depth reduction or attachment gains. The full-mouth groups demonstrated greater reduction in BOP% and number of pockets ? 5 mm and the total treatment time was significantly shorter. The detection frequencies of periodontal pathogens in plaque and saliva showed slight changes with no difference between groups. Conclusion: Single-visit full-mouth mechanical debridement may have limited additional benefits over quadrant-wise therapy in the treatment of periodontitis, but can be completed in a shorter time. [ABSTRACT FROM AUTHOR]

Background: Prostaglandin E2 (PGE2), which exerts its actions via EP receptors (EP1, EP2, EP3, and EP4), is a bioactive metabolite produced by cyclooxygenase (COX)-1 and/or COX-2 from arachidonic acid. In the present study, we investigated whether COX-2-derived PGE2 regulated matrix metalloproteinase (MMP)-3 production in human periodontal ligament (PDL) cells stimulated with interleukin (IL)-1α and which EP receptors were involved in PGE2 regulation of IL-1 α-induced MMP-3 production. Methods: Human PDL cells obtained from periodontally healthy subjects were stimulated with vehicle or IL-1α in the presence or absence of indomethacin (a COX-1/COX-2 inhibitor), NS-398 (a specific COX2 inhibitor), PGE2, EP receptor agonists, dibutyryl cAMP, and forskolin. PGE2 levels were assayed by enzyme-linked immunosorbent assay (ELISA). MMP-3 levels and caseinolytic activities were evaluated by ELISA and casein zymography, respectively. Results: IL-1α enhanced both MMP-3 and PGE2 production. Indomethacin and NS-398 enhanced IL-1α-induced MMP-3 production in PDL cells, to the same extent, although both the agents completely inhibited IL-1α-induced PGE2 production. Exogenous PGE2 reduced IL-1α-induced MMP-3 production in a dose-dependent manner. Butaprost, a selective EP2 agonist, and ONO-AE1-329, a selective EP4 agonist, significantly inhibited IL-1α-induced MMP-3 production, although butaprost was less potent than ONO-AE-1-329. Dibutyryl cAMP, a cAMP analog, and forskolin, an adenylate cyclase activator, significantly inhibited IL-1α-stimulated MMP-3 production in PDL cells. Conclusions: These data suggest that COX-2-dependent PGE2 downregulates IL-1α-elicited MMP-3 production by cAMP-dependent pathways via EP2/EP4 receptors in human PDL cells. cAMP-elevating agents such as EP2/EP4 receptor activators may regulate the destruction of extracellular matrix components in periodontal tissue. [ABSTRACT FROM AUTHOR]

Akizuki T, Oda S, Komaki M, Tsuchioka H, Kawakatsu N, Kikuchi A, Yamato M, Okano T, Ishikawa I. Application of periodontal ligament cell sheet for periodontal regeneration: a pilot study in beagle dogs. J Periodont Res 2005; 40: 245–251.© Blackwell Munksgaard 2005The ultimate goal of periodontal treatment is to regenerate the damaged periodontal support. Although periodontal ligament (PDL) cells are essential for periodontal regeneration, few studies have reported the transplantation of periodontal ligament cells to periodontal defects. We developed a new method to apply periodontal ligament cells as a sheet to the defect. The aim of this study was to investigate the periodontal healing after application of the periodontal ligament cell sheet in beagle dogs.Autologous periodontal ligament cells were obtained from extracted premolars of each beagle dog. Periodontal ligament cell sheets were fabricated using a temperature-responsive cell culture dish. Dehiscence defects were surgically created on the buccal surface of the mesial roots of bilateral mandibular first molars of each dog. In the experimental group (five defects), periodontal ligament cell sheet with reinforced hyaluronic acid carrier was applied to the defect. Only the hyaluronic acid carrier was applied to the contralateral side as a control (five defects). Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Healing of the periodontal defects was evaluated histologically and histometrically.No clinical signs of inflammation or recession of gingiva were observed in both experimental and control groups. In the experimental group, periodontal tissue healing with bone, periodontal ligament and cementum formation was observed in three out of five defects. In the control group, such periodontal tissue formation was not observed except in one defect. Histometric analysis revealed that the formation of new cementum in the experimental group was significantly higher than that in the control group.The periodontal ligament cell sheet has a potential to regenerate periodontal tissue and may become a novel regenerative therapy. [ABSTRACT FROM AUTHOR]

Background: Syndecans are cell surface heparan sulfate proteoglycans (PG) which can bind to and modulate the action of growth factors and extracellular matrix components (ECM). Syndecan 1 has been shown to play important roles during early tooth development and wound healing and repair. Among diverse cells and tissues that comprise the periodontium, the junctional epithelium (JE) constitutes a region of significant anatomic and clinical importance, but the nature of inductive signals and molecules involved in its formation is still unclear. Therefore, this work examines if syndecan-1 is associated with formation of JE, and the distribution of other syndecan family members in the epithelium. Methods: In situ hybridization and immunohistochemical techniques were performed using oral tissues from 4-day-old to 10-week-old mice to investigate the expression of syndecan-1, -2, -3 and -4 mRNAs and their corresponding proteins. Results: Based on in situ hybridization experiments, all syndecan mRNAs were detected in sulcular epithelium (SE), gingival epithelium (GE), and JE with varying intensity and distribution. Syndecan-1 immunostaining was localized on the cell surface while that of syndecan-2 did not show clear membrane localization. Our experiments in the developing tooth demonstrated that syndecan-1 protein followed characteristic patterns of expression during JE formation and that immunore-activity for syndecan-1 protein decreased with age when JE cells underwent terminal differentiation. Conclusion: Results of syndecan-1 mRNA and protein expression patterns suggested that this proteoglycan might be an important molecule during the formation of JE. [ABSTRACT FROM AUTHOR]

Cranial sutures are the growth centres of the skull, enabling expansion of the skull to accommodate rapid growth of the brain. Haploinsufficiency of the humanTWISTgene function causes the craniosynostosis syndrome, Saethre–Chotzen syndrome (SCS), in which premature fusion of the coronal suture is a characteristic feature. Previous studies have indicated thatTwistis expressed in the coronal suture during development, and therefore that it may play an important role in development and maintenance of the suture. TheTwist-null mouse is lethal before the onset of osteogenesis, and the heterozygote exhibits coronal suture synostosis postnatally. In this study we investigated the function of Twist in the development of the mouse coronal suture, by inhibiting Twist synthesis using morpholino antisense oligonucleotides in calvarial organ culture. Decreased Twist production resulted in a narrow sutural space and fusion of bone domains within 48 h after the addition of the morpholino oligonucleotides. Proliferation activity in the sutural cells was decreased, and the expression of osteogenic marker genes such asRunx2andFgfr2was up-regulated in the developing bone domain within 4 h. These results suggest that during establishment of the suture area, Twist is required for the regulation of sutural cell proliferation and osteoblast differentiation. [ABSTRACT FROM AUTHOR]

Background: Papillon Lefevre syndrome (PLS) is a rare autosomal recessive disorder characterized by pal mar-plantar hyperkeratosis and rapid periodontal destruction of both primary and permanent dentitions. It has been shown that the disease is caused by cathepsin C gene (CTSC) mutation leading to the deficiency of cathepsin C enzymatic activity. This study demonstrates the clinical manifestations and CTSC mutational and enzymatic activity analyses in a 5-year-old Thai male PLS patient and his parents. Methods: Peripheral blood samples were obtained for genomic DNA isolation. All exons of the CTSC gene were amplified by polymerase chain reaction (PCR) using specific primers. Mutations were identified by DNA sequencing. Verification of the mutation was performed by digestion of PCR products by restriction endonucleases. The cathepsin C enzymatic activity was determined using the synthetic substrate glycyl-L-arginine-7-amino-4-methylcoumarin. Results: The patient demonstrated classical characteristics of PLS, including hyperkeratotic skin lesions. By the age of 5, all of his primary teeth were extracted due to severe periodontal infection. The parents had no physical abnormalities. The periodontal examination revealed localized mild periodontal destruction. Sequence analysis showed a nucleotide change at position 90 from C>A (c.90C>A) which resulted in a change from cysteine residue to a premature stop codon at the amino acid position 30 in the exon 1. The HpyCH4V digestion revealed that the patient was homozygous, whereas both the father and mother were heterozygous carriers of this mutation. The cathepsin C activity was reduced in the patient's mother, and the activity in the patient was almost completely lost. Conclusions: This is the first study to demonstrate a CTSC gene mutation in a Thai family with PLS, The identified mutation is novel and potentially leads to the drastic reduction of the cathepsin C enzymatic activity. This suggests that the mutation is pathogenetic, causing the PLS. Mutational analysis in more members of the family is warranted to identify whether the mutation is inherited from a common ancestor. [ABSTRACT FROM AUTHOR]

Background: Low-level laser irradiation has been reported to enhance wound healing. Activation of gingival fibroblasts (GF) has a potential for early wound healing in periodontal treatment. The present study aimed to investigate the direct effect of low-level Er:YAG laser irradiation on gingival fibroblasts proliferation in order to clarify the laser effect on healing. Methods: Cultured human gingival fibroblasts (hGF) were exposed to low-power, pulsed Er:YAG laser irradiation with different energy densities ranging from 1.68 to 5.0 J/cm². The cultures were analyzed by means of trypan blue staining and counted under a light microscope. The effect of Er:YAG laser on hGF was also evaluated using a transmission electron microscope (TEM). Results: Cultures irradiated with Er:YAG laser presented faster cell growth when compared with untreated controls. This difference was statistically significant. Transmission electron microscopy revealed rough endoplasmic reticulum, prominent Golgi complexes, and mitochondria after laser irradiation. Conclusions: Our results showed that the low-level Er:YAG laser irradiation stimulates the proliferation of cultured gingival fibroblasts. The optimal stimulative energy density was found to be 3.37 J/cm². This result suggests that Er:YAG laser irradiation may be of therapeutic benefit for wound healing. [ABSTRACT FROM AUTHOR]

Investigates the effectiveness of the prognosis of dialysis patients with renal cell carcinoma based on the detection approach of the disease. Consideration of screening of patients without symptoms and examination of patients after the appearance of the symptoms; Comparison of two groups of patients with renal cell carcinoma; Method used to compare survival rates; Acquisition of death hazard ratio; Reduction of risk of death in groups with detection due to symptoms; Patient characteristics with best chances of survival rate from renal cell carcinoma detected by screening.

Umeda M, Miwa Z, Takeuchi Y, Ishizuka M, Huang Y, Noguchi K, Tanaka M, Takagi Y, Ishikawa I. The distribution of periodontopathic bacteria among Japanese children and their parents. J Periodont Res 2004; doi: 10.1111/j.1600-0765.2004.00754.x© Blackwell Munksgaard 2004It is not well known how periodontopathic bacteria colonize in the oral cavity during childhood. The purpose of this study was to investigate the distribution of periodontopathic bacteria in oral cavities of children and their parents and the relationship between the bacterial findings and clinical parameters.Fifty-six children (mean age: 8.3 ± 3.5, range: 1–15 years), including 15 with deciduous dentition, 26 with mixed dentition and 15 with permanent dentition, and their parents participated in this study. Whole saliva and dental plaque of the children and whole saliva of their parents were collected for detection of seven species of periodontopathic bacteria (Actinobacillus actinomycetemcomitans,Tannerella forsythensis(Bacteroides forsythus),Campylobacter rectus,Porphyromonas gingivalis,Prevotella intermedia,Prevotella nigrescensandTreponema denticola) using the polymerase chain reaction method. Clinical parameters including simplified Oral Hygiene Index and Papillary-Marginal-Attachment Index were recorded for the children and their accompanied parents.The detection frequencies ofT. forsythensis,C. rectus,P. nigrescens,T. denticola,A. actinomycetemcomitans and P. gingivalisin the oral cavities of children were 42.9%, 94.6%, 42.9%, 48.2%, 1.8% and 8.9%, respectively.T. forsythensis,P. gingivalisandT. denticolawere detected more frequently in the saliva of parents (54.8%, 54.8%, 88.1%, respectively) than in the saliva of children (25.5%, 7.3%, 41.8%, respectively). Different detection frequencies ofP. nigrescenswere found among the oral cavities of children with deciduous, mixed and permanent dentitions. In mixed dentition, females harboredT. forsythensismore frequently than males did. Children who harboredT. forsythensis,P. intermedia,P. nigrescensandT. denticolashowed high scores for oral debris measurement by simplified Oral Hygiene Index.T. forsythensis,P. intermediaandP. nigrescenswere detected more frequently in children whose parents were positive for these pathogens than in children whose parents were negative.High plaque retention seems to promote the colonization of periodontal pathogens in the oral cavities of children.T. forsythensis,P. intermediaandP. nigrescenswere detected more frequently in the oral cavities of children whose parents already harbored these bacteria. Familial transmission of these bacteria is suggested. [ABSTRACT FROM AUTHOR]

It is now beyond question that dental plaque is the main etiologic factor in the pathogenesis of periodontal diseases. However, recent advances have modified concepts regarding the etiology of these diseases. Several other aspects including genetic, host and environmental factors modulate the course of periodontal infections and this information has directed periodontal research into many basic, but complicated, mechanisms at molecular and cellular levels. The role of microorganisms in initiation and progression of periodontal infections was confirmed by numerous studies conducted over the years.

Mechanical debridement consisting of scaling and root planing is an important procedure in the treatment of periodontal diseases. By root instrumentation, toxic substances can be removed from periodontally affected root surfaces resulting in the biologic/detoxic condition of the root surface, which is favorable for periodontal tissue healing. Meticulous scaling and root planing is performed during the surgical and nonsurgical phases of periodontal treatment, as well as in the maintenance phase. Scalers can be divided into manual, power-driven, and other types.

The microbiologic etiology of periodontal disease has been confirmed by numerous studies conducted over the years. Periodontal treatment thus focuses on the thorough removal of plaque, calculus, and plaque products. Nonsurgical mechanical treatment, which includes mechanical plaque control, scaling and root planing, is the first recommended step and is an indispensable phase of periodontal therapy. One of the significant advances in periodontal research is the identification of specific pathogenic species in periodontitis.

Progress in understanding the pathogenesis of periodontal diseases has paved the way for new approaches in prevention, diagnosis, treatment, and prognosis. But ever since the old days, the control of periodontal disease has relied upon removal of bacterial deposits from the supra- and sub-gingival environment. Although specific microorganisms have been considered potential pathogens, it appears that there is no single etiologic agent for inflammatory periodontal diseases. The success of periodontal therapy depends on reduction of pathogenic bacteria present in the dental plaque associated with teeth and other ecologic niches within the oral cavity.

This article reviews the current and potential applications of laser technology in nonsurgical therapy for the treatment of periodontal diseases. Based on its various characteristics, such as ablation or vaporization, hemostasis, and sterilization effect, laser treatment may serve as an adjunct or alternative to conventional, mechanical periodontal therapy. It also deals with recent advances in nonsurgical laser therapy for periodontal disease, and will briefly describe the advantages and disadvantages of various laser types.

Ishikawa I, Aoki A, Takasaki AA. Potential applications of Erbium:YAG laser in periodontics. J Periodont Res 2004; doi: 10.1111/j.1600-0765.2004.00738.x© Blackwell Munksgaard, 2004 Since lasers were introduced for the treatment of oral diseases, there has been considerable advancement in technology. As a result, numerous laser systems are currently available for oral use. Neodymium:Yttrium–Aluminum:Garnet (Nd:YAG), carbon dioxide (CO2) laser and the semiconductor Diode lasers have already been approved by the US Food and Drug Administration for soft tissue treatment in oral cavity. The Erbium:YAG (Er:YAG) laser was approved in 1997 for hard tissue treatment in dentistry and recent studies have reported positive results. This suggests that the Er:YAG laser system is a promising apparatus, which will be able to revolutionize and improve dental practice, in particular periodontal treatment. In this mini-review, we would like to describe the positive characteristics of the Er:YAG laser which indicate its potential as a new treatment modality in periodontics. Recent findings are summarized briefly to evaluate the potential of the Er:YAG laser for clinical application in periodontics. The Er:YAG laser possesses suitable characteristics for oral soft and hard tissue ablation. Recently, it has been applied for effective elimination of granulation tissue, gingival melanin pigmentation and gingival discoloration. Contouring and cutting of bone with minimal damage and even or faster healing can also be performed with this laser. In addition, irradiation with the Er:YAG laser has a bactericidal effect with reduction of lipopolysaccharide, high ability of plaque and calculus removal, with the effect limited to a very thin layer of the surface and is effective for implant maintenance. The Er:YAG laser seems to be an effective tool for periodontal therapy, however, further clinical and basic investigations are required to confirm its clinical application. [ABSTRACT FROM AUTHOR]

Background: Periodontal ligament (PDL) cells form mineralized nodules in vitro. Ascorbic acid is known to be required in this process, although its effect on osteoblastic differentiation of PDL cells remains unclear. The purpose of this study was to determine the role of ascorbic acid on the early osteoblastic differentiation of PDL cells, with regard to alkaline phosphatase (ALP) activity, type I collagen production and integrin expression. Methods: Cultured PDL cells were stimulated at confluence with ascorbic acid in the presence or absence of type I collagen inhibitor and blocking antibodies to integrins. After stimulation, the cells and culture supernatants were examined for ALP activity, type I collagen production, and integrin expression. The ALP activity was measured using a colorimetric assay with ρ-nitrophenyl phosphate and ALP staining. Enzyme-linked immunosorbent assay (ELISA) was used to determine type I collagen production, and ELISA and flow cytometric analysis were employed for assessment of integrin expression. Results: Both ALP activity and type I collagen production were upregulated when PDL cells were cultured in the presence of ascorbic acid (200 µM). Inhibitor of the formation of collagen triple helices and blocking antibodies to α2β 1 integrin inhibited ALP activity by 50% in ascorbic acid-stimulated PDL cells. Furthermore, ascorbic acid increased the cell surface expression of α2β integrin. Conclusions: Our findings indicated that ascorbic acid increases the ALP activity of PDL cells via type I collagen production and also enhances the expression of α2β integrin, which is a major receptor of type I collagen. These results suggest that ascorbic acid promotes the osteoblastic differentiation of PDL cells by modulating type I collagen-α2β integrin interaction. [ABSTRACT FROM AUTHOR]

Nakamura T, Nitta H, Ishikawa I. Effect of low dose Actinobacillus actinomycetemcomitans lipopolysaccharide pretreatment on cytokine production by human whole blood. J Periodont Res 2004; 39; 129–135. © BlackwellMunksgaard, 2004 Periodontal disease is known to influence the systemic condition in various ways, and the bacteria and their products, such as lipopolysaccharides (LPS), may spread from periodontal lesions via the systemic circulation to affect distant organs. The level of LPS in plasma from such patients is reported to be very low, and this low level of LPS is suspected to have priming or desensitizing effect. Thus, we investigated the effects of low dose LPS pretreatment on LPS-dependent cytokine production by whole blood cells ex vivo. Blood samples obtained from seven systemically and periodontally healthy individuals were pretreated with or without 5 pg/ml Actinobacillus actinomycetemcomitans LPS, followed by further stimulation with 1 ng/ml A. actinomycetemcomitans LPS. The concentrations of interleukin-1 beta (IL-1β), IL-6, IL-10 and tumor necrosis factor-alpha (TNF-α) in the culture supernatants were then determined using enzyme-linked immunosorbent assay (ELISA). In addition, intracytoplasmic cytokine staining of whole blood cells was performed for flow cytometry. Pretreatment with 5 pg/ml A. actinomycetemcomitans LPS significantly enhanced the production of IL-1β and IL-6 from whole blood when further induced by 1 ng/ml LPS (1.72 times higher for IL-1β, 2.18 times higher for IL-6 than without pretreatment). The pretreatment did not enhance the production of either TNF-α or IL-10. Intracytoplasmic staining showed that the monocyte fraction was primarily involved in producing IL-1β and IL-6. Flow cytometric analysis revealed that pretreatment increased the number of IL-1β and IL-6 producing cells as well as mean fluorescence intensity of the stained cells. A low dose of bloodstream LPS found in periodontitis patients appears to be sufficient to prime monocytes, and may be capable of affecting the systemic responses of immune and inflammatory cells. [ABSTRACT FROM AUTHOR]

Background: Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis. Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis, although the evidence is controversial. The aim of the present study was to investigate the prevalence of periodontopathic bacteria and to clarify the microbiological features of aggressive periodontitis in Japanese patients. Methods: Subgingival plaque was collected from 50 aggressive periodontitis (AgP) patients (localized 10, generalized 40). Samples from 35 generalized chronic periodontitis (CP) patients and 18 healthy subjects were examined as controls. Plaque samples were examined using culture and polymerase chain reaction (PCR) method. Results: The prevalence of A. actinomycetemcomitans was relatively low in the localized (20%) and generalized (17.5%) AgP patients, with no significant difference observed in detection frequencies between AgP and the control groups (CP 8.6%, healthy 0%). On the other hand, Tannerella forsythensis (formerly Bacteroides forsythus), Campylobacter rectus, P. gingivalis, and Treponema denticola were frequently detected in localized as well as generalized aggressive periodontitis patients. The prevalence and proportion of P. gingivalis correlated with severity of clinical attachment loss in both localized and generalized aggressive periodontitis. Conclusions: T. forsythensis, C. rectus, P. gingivalis, and T. denticola were the predominant periodontopathic bacteria of aggressive periodontitis patients in Japan. Although A. actinomycetem- comitans was also detected in AgP patients, the prevalence of this bacterium was much lower than that or P. gingivalis. [ABSTRACT FROM AUTHOR]

Background: As periodontal tissues are constantly exposed to mechanical stress during mastication, the relationship between mechanical stimulation and biochemical phenomena has been extensively investigated. Objectives: The aim of the present study was to assess the change in the production of angiogenic regulators produced by human gingival fibroblasts (HGF) and periodontal ligament fibroblasts (HPLF), cultured on a flexible substrate, before and after application of cyclic tensile stretching. Materials and methods: Both cell types were stretched in a Flexercell Strain Unit to 7, 14 and 21% elongation, at a frequency of 12 cycles/min. Medium cultured with HGF or HPLF was examined by enzyme-linked immunosorbent assay (ELISA) for vascular endothelial growth factor (VEGF), Western blotting of pigment epithelium-derived factor (PEDF) and in vitro angiogenesis assay. The residual cells were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) for both VEGF and PEDF mRNA expression. Results: Stretching increased the VEGF mRNA level and VEGF secretion in both HGF and HPLF. The concentration of VEGF in the conditioned medium of the stretched HPLF was almost the same as that of stretched HGF. In the in vitro angiogenesis assay, the conditioned medium of HPLF after stretching showed a dramatic increase in tube formation. In contrast, stretched HGF did not show enhanced tube formation, despite the increase in VEGF secretion by stretched HGF. The mRNA levels of PEDF, an inhibitor of angiogenesis, were higher in HGF than HPLF. The protein level of PEDF in HGF was also higher than that in HPLF. Conclusion: These findings suggest that under mechanical stress HPLF promotes angiogenesis via expression of VEGF, whereas under the same conditions angiogenesis is not promoted in HGF, due to the expression of PEDF. [ABSTRACT FROM AUTHOR]

Background: Periodontal ligament fibroblasts (PDLFs) are the cells essential for periodontal regeneration. PDLFs comprise a heterogeneous cell population and consist of several cell subsets that differ in their function. It is known that PDLFs produce osteoblast-related extracellular matrix proteins and show higher alkaline phosphatase (ALP) activity compared with gingival fibroblasts (GFs), implying that PDLFs have osteogenic characteristics. The aim of the present study was to isolate the osteogenic population of PDLFs according to their expression of ALP. Methods: PDLFs and gingival fibroblasts were separated into two population, ALP-positive and ALP-negative, with an immunomagnetic method using a monoclonal antibody against human bore type ALP and magnetic beads conjugated with a secondary antibody. Expression of basic fibroblast growth factor (bFGF) receptor and transforming growth factor (TGF)-β receptor was investigated in these two populations. Osteoblast-related molecules, osteocalcin, and bone sialoprotein; ALP activity; and effect of bFGF on proliferation were also compared. Results: Effective separation was confirmed in both PDLFs and GFs by flow cytometry. The expression of FGF receptor (FGFR) and TGF-β receptor was significantly higher in ALP-positive PDLFs than in ALP-negative PDLFs. ALP-positive PDLFs also expressed higher mRNA levels of osteocalcin and bone sialoprotein compared with ALP-negative PDLFs. The mitogenic effect of bFGF on ALP-positive PDLFs was greater than that of ALP-negative PDLFs. Conclusions: These results indicate that osteoblastic and/or cementoblastic PDLF subsets could be isolated from the PDLF populations using an immunomagnetic method. Magnetic isolation of PDLFs may be a useful tool to obtain the cells which will potentially induce mineralization on the root surface. [ABSTRACT FROM AUTHOR]