Bactericidal effects of a high-power, red light-emitting diode on two periodontopathic bacteria in antimicrobial photodynamic therapy in vitro

AIM

  Light-emitting diodes have been investigated as new light activators for photodynamic therapy. We investigated the bactericidal effects of high-power, red light-emitting diodes on two periodontopathic bacteria in vitro.

METHODS

  A light-emitting diode (intensity: 1100 mW/cm(2) , peak wavelength: 650 nm) was used to irradiate a bacterial solution for either 10 or 20 s. Bacterial solutions (Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans) at a concentration of 2.5 × 10(6) c.f.u./mL were mixed with an equal volume of either methylene blue or toluidine blue O (0-20 μg/mL) and added to titer plate wells. The plate wells were irradiated with red light-emitting diode light from a distance of 22 or 40 mm. The contents were diluted, and 50 μL was smeared onto blood agar plates. After 1 week of culturing, bacterial c.f.u. were counted.

RESULTS

  The light-emitting diode energy density was estimated to be approximately 4 and 8 J/cm(2) after 10 and 20 s of irradiation, respectively. Red light-emitting diode irradiation for 10 s from a distance of 22 mm, combined with methylene blue at concentrations >10 μg/mL, completely killed Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.

CONCLUSION

  High-power, red light-emitting diode irradiation with a low concentration of dye showed effective bactericidal effects against two periodontopathic bacteria.

Comparison of different tissue-derived stem cell sheets for periodontal regeneration in a canine 1-wall defect model

Cytotherapeutic approaches have been investigated to overcome the limitations of existing procedures for periodontal regeneration. In this study, cell sheet transplantation was performed using three kinds of mesenchymal tissue (periodontal ligament, alveolar periosteum, and bone marrow)-derived cells to compare the differences between cell sources in a canine severe defect model (one-wall intrabony defect). Periodontal ligament cells (PDLCs), iliac bone marrow mesenchymal stromal cells (BMMSCs), and alveolar periosteal cells (APCs) were obtained from each dog; a total of four dogs were used. Three-layered cell sheets of each cell source supported with woven polyglycolic acid were autologously transplanted to the denuded root surface. One-wall intrabony defects were filled with a mixture of β-tricalcium phosphate (β-TCP) and collagen. Eight weeks after the transplantation, periodontal regeneration was significantly observed with both newly formed cementum and well-oriented PDL fibers more in the PDLC group than in the other groups. In addition, nerve filament was observed in the regenerated PDL tissue only in the PDLC group. The amount of alveolar bone regeneration was highest in the PDLC group, although it did not reach statistical significance among the groups. These results indicate that PDLC sheets combined with β-TCP/collagen scaffold serve as a promising tool for periodontal regeneration.

Validation of human periodontal ligament-derived cells as a reliable source for cytotherapeutic use

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 settings.

Comparison of characteristics of periodontal ligament cells obtained from outgrowth and enzyme-digested culture methods

OBJECTIVE

Periodontal ligament (PDL) cells have an important role in periodontal regeneration. The unique characteristics of PDL cells, mainly outgrown cells derived from PDL tissue, have been investigated. Recently, mesenchymal stem cells have been obtained from PDL tissue using enzyme digestion. The differences in properties of those PDL cells cultured by the two methods (outgrowth and enzyme digestion) are unclear. The objective of this study was to investigate the characteristics of PDL cells obtained by these methods.

METHODS

PDL cells from extracted tooth were cultured using outgrowth and enzyme digest methods. Cell proliferation, colony-forming activity and differentiation capacity to osteoblast, adipocyte and chondrocyte were compared. Gene expressions for PDL cells, mesenchymal stem cells and fibroblasts were also investigated by reverse transcription polymerase chain reaction. Procollagen type I c-peptide (PIP) production was measured using an enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

PDL cells cultured by enzyme digest methods showed a higher proliferation rate, colony-forming activity and differentiation capacity into osteoblast, adipocyte and chondrocyte than those in PDL cells by outgrowth method. CD166, one of the mesenchymal stem cell markers, was slightly higher in enzyme-digested PDL than in outgrowth PDL, whilst gene expressions for type 1 collagen alpha 1 and type 3 collagen were higher in outgrown PDL cells. Moreover, outgrowth PDL exhibited higher PIP production than enzyme-digested PDL cells.

CONCLUSION

PDL cells obtained by outgrowth and enzyme digestion showed different characteristics. The enzyme digestion method yielded cells with higher proliferation rate and mesenchymal stem cell-like properties, whereas cells with fibroblast-like properties were collected in the outgrowth method. PDL cell properties by different culture methods may provide information for inventing new therapeutic uses of PDL cells.

Long-term natural history of acquired cystic disease of the kidney

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 m(2) 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.

A retrospective study of nine cases of Acanthamoeba keratitis

Purpose

To evaluate the clinical features of Acanthamoeba keratitis in nine patients diagnosed at Dokkyo Medical University Koshigaya Hospital, Saitama, Japan.

Methods

In nine eyes of nine patients, Acanthamoeba keratitis was diagnosed by direct light microscopy of corneal scrapings stained by the Parker ink-potassium hydroxide method between September 2006 and September 2009. Their clinical features and course were studied retrospectively. Antifungal eye drops, systemic antifungal therapy, and surgical debridement of the corneal lesions were performed in all patients.

Results

At presentation, the clinical stage was initial in six cases, transient in one case, and complete in two cases. The patients were all contact lens wearers who had washed their lens storage cases with tap water. After treatment, final visual acuity was improved in six cases, unchanged in one case, and worse in two cases. The patient with the worst final vision (hand motion) had rheumatoid arthritis and was taking oral prednisolone, which led to corneal perforation and prevented adequate debridement from being done.

Conclusion

Acanthamoeba keratitis is closely related to wearing contact lenses and washing the lens storage case with tap water. Although final visual acuity improved after treatment in most patients, insufficient surgical debridement resulted in a poor visual prognosis.

Left ventricular-right atrial communication by perforation of the atrioventricular portion of the membranous septum and severe aortic valve regurgitation caused by infective endocarditis

We report the case of acquired left ventricle (LV) to right atrial (RA) communication through an aneurysm of the atrioventricular septum caused by infectious endocarditis. A severe aortic valve regurgitation and destruction of the aortic valve was detected by echocardiography. Transesophageal echocardiography revealed a flail aortic valve with vegetation and abnormal shunt flow from the LV to RA with ruptured aneurysm of the membranous septum. An abscess cavity of the aortic ring was introduced. Because of worsening congestive heart failure, the patient underwent emergency aortic valve replacement and patch closure of the communication of the membranous septum. The patient's postoperative course was uneventful.

Association between periodontitis and anti-cardiolipin antibodies in Buerger disease

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 beta-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 >or=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.

Long-term histologic analysis of bone tissue alteration and healing following Er:YAG laser irradiation compared to electrosurgery

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.

Periodontal ligament cell sheet promotes periodontal regeneration in athymic rats

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.

Multi-center intervention study on glycohemoglobin (HbA1c) and serum, high-sensitivity CRP (hs-CRP) after local anti-infectious periodontal treatment in type 2 diabetic patients with periodontal disease

The purpose of this study was to examine whether periodontal treatment incorporating topical antibiotic therapy affects on levels of glycohemoglobin (HbA1c) and serum high-sensitivity C-reactive protein (hs-CRP) in type 2 diabetic patients with periodontal disease, and to explore the relationship between CRP and glycemic control. The whole intervention group (n=32), which underwent anti-infectious periodontal treatment, showed only transient reduction in HbA1c levels without any change in hs-CRP, while the control group (n=17) did not show any changes in HbA1c or hs-CRP. Multiple regression analysis of all subjects revealed that BMI and change in hs-CRP correlated significantly with the reduction of HbA1c at 6 months after the periodontal treatment. Based on the results of multiple regression analysis, the intervention group was subdivided into two groups: those in which hs-CRP levels decreased (CRP-D group), and those in which hs-CRP levels unchanged or increased (CRP-N group) (n=16, respectively), and re-analysis was conducted based upon these subgroups. In the CRP-D subgroup, HbA1c was significantly reduced at the end of the study, but it did not decrease in the CRP-N subgroup. The decrease of HbA1c in the CRP-D subgroup following periodontal treatment was significantly greater than that in the CRP-N subgroup. BMI of each group remained unchanged in this study at the end of the study. Thus, the results suggested that periodontal treatment with topical antibiotics improves HbA1c through reduction of CRP, which may relate to amelioration of insulin resistance, in type 2 diabetic patients with periodontal disease.

Changes in serum interleukin-6, C-reactive protein and thrombomodulin levels under periodontal ultrasonic debridement

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.