Electrocatalytic oxidation of hydrazine on a carbon paste electrode modified by hybrid hexacyanoferrates of copper and cobalt films

A stable electroactive thin film of hybrid copper-cobalt hexacyanoferrate (CuCoHCF) was electrodeposited on a carbon paste electrode by cyclic voltammetry. The modified electrode exhibits good catalytic activity for the oxidation of hydrazine at a reduced overpotential with good sensitivity in the wide concentration range 0.1–12 mM hydrazine. A Tafel plot, derived from voltammograms, indicated a one-electron charge transfer process to be the rate-limiting step and the overall number of electrons involved in the catalytic oxidation of hydrazine was found to be 4. The CuCoHCF modified-electrode exhibited stable electrochemical responses in a wide pH range 2–10 and showed excellent electrocatalytic activity toward the oxidation of hydrazine in 0.1 M phosphate buffer, pH 7. The diffusion coefficient of hydrazine and rate constant for the catalytic reaction were also evaluated. Finally the proposed modified electrode exhibited several attractive features, such as simple preparation, fast response, good stability and repeatability and could be applied as an amperometric sensor for hydrazine.     

Gingival crevicular fluid collagenase-2 (MMP-8) test stick for chair-side monitoring of periodontitis

BACKGROUND: A rapid chair-side test based on the immunological detection of elevated levels of collagenase-2 (matrix metalloproteinase-8, MMP-8) in gingival crevicular fluid (GCF) was developed to identify and monitor the course and treatment of adult periodontitis. METHODS: MMP-8 was determined in GCF from periodontitis (11 patients, 90 sites), gingivitis (10 patients, 58 sites) and healthy control (8 patients, 59 sites) sites (i) by a test stick incorporating monoclonal antibodies to two epitopes on MMP-8 and (ii) by measuring MMP-8 concentration by a quantitative immunofluorometric assay. Patients with adult periodontitis were treated by scaling and root planing (SRP) and received oral hygiene instructions. GCF MMP-8 testing and clinical measurements were done before and after SRP. RESULTS: MMP-8 GCF levels and chair-side test differentiated periodontitis from gingivitis and healthy control sites. MMP-8 GCF levels > 1 mg/l and positive chair-side test identified especially severe periodontitis sites. A positive and negative test stick result, the outcome of which was rapidly detectable in 5 mins, in GCF correlated well with MMP-8 immunofluorometric assay analysis from the collected GCF samples and the severity of periodontitis. Scaling and root planing reduced the MMP-8 levels in severe periodontitis sites with positive MMP-8 test and gingival probing pocket depth (PD) > 5 mm before treatment. The test stick result and the quantitative assay were discrepant in only 18 of the 207 sites tested, thus agreement was very good (kappa = 0.81). With a threshold of 1 mg/l MMP-8 activity the chair-side test provided a sensitivity of 0.83 and specificity of 0.96 (n = 207). CONCLUSION: The MMP-8 test can be used to differentiate periodontitis from gingivitis and healthy sites as well as to monitor treatment of periodontitis. A reduction in GCF MMP-8 levels and a change in test stick result provide a means to optimize patient control during maintenance of periodontal treatment.     

Granulocyte elastase in gingival crevicular fluid: improved monitoring of the site-specific response to treatment in patients with destructive periodontitis

Abstract In 13 patients with severe destructive periodontitis. the response to periodontal therapy was estimated by granulocyte elastase level in gingival crevicular fluid (GCF). 62 sites were classified according to changes of probing depths (PD) and quantitative bone height (BH%) before and after 5–year regular maintenance treatment: (i) 17 consistently healthy sites with no changes of PD and BH%; (ii) 6 initially healthy sites with deterioration in PD and BH%; (iii) 14 diseased sites with improvement in PD and BH%; (iv) 25 diseased sites with no improvement in PD and BH%. GCF was collected by an intracrevicular washing system. The released elastase in the supernatants (EA-S) and the cell-bound elastase in the pellets (EA-P) were determined with a low molecular weight substrate specific for granulocyte elastase. The ratio of EA-S and EA-P (S/P-ratio) was used as a relative measure of elastase released by the granulocytes present. The sites classified as diseased with no improvement or initially healthy but deteriorating, had significantly higher EA-S, EA-P and S/P-ratios than the consistently healthy sites or diseased but improving sites (p < 0.01). Both EA-S and S/P-ratio showed strongly positive correlations with the current levels of gingival inflammation and periodontal destruction (p < 0.001). The present study suggests that increased elastase level is associated with disease progression, and may be used to monitor the response to longitudinal maintenance therapy.     

Contribution of individual drugs to gingival overgrowth in adult and juvenile renal transplant patients treated with multiple therapy

Abstract. Drug regimens for transplantation often consist of multiple therapeutic agents and may result in drug-induced gingival overgrowth (DIGO). The aim of this study was to investigate the contribution of individual drugs in renal transplant patients. 147 adults (19–84 years) and 60 juveniles (3–18 years) were scored for DIGO and other clinical variables. Duration of treatment, dosage of drugs per kg body weight and serum cyclosporin levels were recorded. 44% of adults and 27% of children had DIGO. All patients were receiving prednisolone. More adults than children were administered cyclosporin, the reverse was true of azathioprine ( P 0.01), Explanatory models were evaluated by stepwise ordinal polynomial logistic regression. Statistically significant explanation ( P 0.05) of DIGO was afforded by prednisolone, nifedipine and azathioprine concentrations in adults and by cyclosporin, nifedipine and azathioprine concentrations in juveniles. Prednisolone and azathioprine were inversely related to the degree of DIGO. Plaque and irregularity scores, lip coverage and mouthbreathing status showed significant additional explanation in adults, replacing nifedipine and azathioprine in the final model. Irregularity was additionally explanatory in children, but no other clinical variables. A larger proportion of the variance of DIGO was explained by the available variables in children than in adults (pseudo r ²=0.50 versus 0.25). The degree of DIGO in renal transplant patients is influenced by the dosage of a number of individual components of multiple drug therapy independently of the presence of local clinical factors.     

Periodontal tissue engineering and regeneration: Consensus Report of the Sixth European Workshop on Periodontology

Aim: To review the scientific preclinical background and clinical studies of current methods of periodontal regeneration in the treatment of infrabony defects and soft tissue deficiencies
Method: Five commissioned review papers including two systematic reviews were scrutinized by a group of experts in order to derive consensus conclusions, clinical relevance/implications and to propose future research requirements.
Results: The following five papers were assessed:
  1. Biological mediators and periodontal regeneration: a review of enamel matrix proteins at the cellular and molecular levels.
  2. Regeneration of periodontal tissues: combination of barrier membranes and grafting materials – Biological foundation and preclinical evidence.
  3. Clinical outcomes with bioactive agents alone or in combination with grafting or GTR
  4. Treatment of gingival recession with coronally advanced flap procedures. A systematic review.
  5. Soft tissue management at implant sites     

ICAM-1-expressing pocket epithelium, LFA-1-expressing T cells in gingival tissue and gingival crevicular fluid as features characterizing inflammatory cell invasion and exudation in adult periodontitis

Activated T lymphocytes constitute a major component of inflammatory cells in the early periodontal lesion, and also appear in the gingival crevicular fluid. In an attempt to clarify the relationship between the ICAM-1 (CD54) expression of pocket epithelium in gingiva and the infiltrating lymphocyte population, we carried out an analysis of CD11a⁺ (LFA-lα), CD25⁺ (IL-2Rα) and CD4⁺ (Th) cells subjacent to ICAM-1-expressing pocket epithelia and CD11a⁺ CD25⁺CD4⁺ cells in gingival crevicular fluid (GCF). GCF was collected by crevicular washing from 16 patients with periodontitis (P group) and 3 subjects with healthy gingiva (H group). Peripheral blood (PB) was collected at the same time. Mononuclear cells were isolated by Ficoll-paque gradient centrifugation from GCF and PB. Monoclonal antibodies (mAb) to CD11a, CD25, and CD4 were used for three-color flow cytometry. Gingival biopsies were obtained from 7 patients in P group and 3 subjects in H group. Serial cryostat sections (6 μm in thickness) were prepared from each biopsy, on which a double staining was performed. The number of CD11a⁺ CD25⁺ CD4⁺ cells and the fluorescence intensity of FITC conjugated anti-CD 11a were significantly higher in GCF than in PB (p≤0.001 to p≤0.01). CD11a⁺ CD25⁺CD4⁺ cells were not detected in GCF in H group. The pocket epithelia expressed CD54 in P group, but not in H group. The number of CD11a⁺, CD25⁺ and CD4⁺cells infiltrating the connective tissue subjacent to the upper, middle and lower parts of the CD54 positive pocket epithelium (n=16) was 141±26, 38±13, 144±29 (cells/0.04 mm²), respectively, whereas in the CD54 negative pocket epithelium, it was (n=5) 9±2, 3±1, 8±3. In P group, the CD11a⁺CD25⁺CD4⁺cell number in GCF correlated with CD25⁺, CD11a⁺cells in the connective tissue subjacent to the CD54⁺pocket epithelium. These results indicate that expression of ICAM-1 in pocket epithelium is relevant to the migration of CD11a, CD25, CD4 positive cells in connective tissue subjacent to the pocket epithelium into the periodontal pocket. Assessing the relationship of our findings and other adhesion molecules would offer important clues to the understanding of T cell migration in affected gingiva.     

Detection of, and anti-collagen antibody produced by, CD5-positive B cells in inflamed gingival tissues

This study was performed to investigate the frequency and distribution of CD5-positive (CD5+) B cells in inflamed gingival tissues using flow cytometric and immunohistochemical analyses. The ability of CD5+ B cells to produce anti-type I collagen antibody was also examined. CD5+ B cells expressed "low" fluorescence intensity in the peripheral blood of both healthy subjects and patients with adult periodontitis. However, in inflamed gingival tissues the intensity of this surface marker was high. The percentage of B cells bearing CD5 surface marker was statistically higher in gingiva than in peripheral blood obtained from both the patients and healthy subjects. These CD5+ B cells were observed in gingival subepithelial connective tissues from the bottom to the middle of the periodontal pocket. This area showed destruction of collagen fibers and dense cell infiltrations. Anti-collagen IgG antibody level in patients' gingival crevicular fluids (GCF) was higher than that in sera from healthy subjects, and slightly higher than in autologous sera. IgM anti-collagen antibody in GCF was lower than in autologous sera and in sera from healthy subjects. EBV-transformed CD5+ B cells produced considerably more IgM and IgG antibody to collagen than CD5- B cells. Therefore CD5+ B cells may contribute to the pathogenesis of inflamed gingival tissues.     

LYSANDA PASTE: A NEW OPTION FOR ROOT-END FILLING

This study aimed to compare the apical sealing of root-end fillings performed with Lysanda (zinc oxide-eugenol paste) with radiopacifiers (iodoform or zinc oxide) and calcium hydroxide. Root-end cavities were prepared and filled with different materials, as follows: Group I – Lysanda paste with iodoform; Group II – Lysanda paste with iodoform and calcium hydroxide; Group III – Lysanda paste with iodoform and zinc oxide; Group IV – Lysanda paste with zinc oxide; Group V – mineral trioxide aggregate (MTA). After filling, the teeth were immersed in 2% methylene blue for analysis of marginal leakage. It was observed that marginal leakage occurred in all groups. Lysanda paste with iodoform showed the lowest leakage, with no statistically significant difference compared to the other groups. All materials can be considered as good options for root-end filling.     

The Effect of Gingival Retraction Procedures on Periodontal Indices and Crevicular Fluid Cytokine Levels: A Pilot Study

PURPOSE: The purpose of this study was to examine the effects of placement of retraction cord subgingivally upon periodontal indices including plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP), and attachment level (AL), as well as gingival crevicular fluid (GCF) and TNF-alpha levels. METHODS: Ten teeth in 6 patients who were periodontally healthy were selected. These teeth had pocket depths of 3 mm or less, no evidence of significant loss of attachment, BOP, or plaque accumulation. The patients each received an oral prophylaxis. The following week, baseline measurements of periodontal indices and TNF-alpha were taken and the retraction cord was placed for 15 minutes. Following removal, the patients were dismissed. The periodontal indices measured included PI, GI, PD, BOP, and AL. In addition, the levels of TNF-alpha in GCF, were investigated. These measurements were made before gingival retraction as a baseline and on the 1st, 3rd, 7th, 14th, and 28th days post retraction. RESULTS: A repeated measures ANOVA showed that TNF-alpha levels in GCF were significantly increased at all five intervals after gingival retraction compared to the baseline. The mean TNF-alpha level peaked at Day 1 (0.90 +/- 0.62), then declined at Days 3 (0.53 +/- 0.16), 7 (0.43 +/- 0.08), 14 (0.47 +/- 0.10), and 28 (0.43 +/- 0.08) but was still elevated 54% above baseline at Day 28, p < 0.01. The GI was significantly elevated at Day 1 (0.9 +/- 0.49), p < 0.01; Day 3 (0.53 +/- 0.32); and Day 7 (0.33 +/- 0.33), p < 0.05. Unlike TNF-alpha, GI recovered to the baseline by day 14. Other periodontal parameters, PI, PD, BOP, and AL were not significantly altered by the gingival retraction procedure. CONCLUSION: This pilot study supports the previous research that gingival retraction causes an acute injury that heals clinically in 2 weeks as is indicated by the GI. It also provides the first evidence that gingival retraction results in an elevation of the proinflammatory cytokine, TNF-alpha, in GCF.     

Localization of interleukin-1 (IL-1) mRNA-expressing macrophages in human inflamed gingiva and lL-1 activity in gingival crevicular fluid

The exact cell type and site(s) involved in interleukin-1 (lL-1) production during gingival inflammation was determined by combining immunohistochemistry and in situ hybridization. IL-1 messenger RNA (mRNA)-expressing cells in human inflamed gingiva were identified as macrophages. The rate of IL-α mRNA expression in these macrophages was the same as IL-1 β mRNA expression. The rate of IL-1 mRNA expression was higher in connective tissue furthest from the pocket epithelium, although more macrophages were present at the connective tissue subjacent to the pocket epithelium. The IL-1 activity in gingival crevicular fluid (GCF) obtained from inflamed gingiva was higher than that from healthy gingiva and decreased after periodontal therapy. The IL-1 activity in GCF was almost completely abolished by the addition of anti-IL-1α antibody but not by anti-IL-1 β antibody, indicating that IL-1α is the predominant form in GCF. However, the IL-1 activity in GCF was unrelated to the number of IL-1 mRNA-exprerssing macrophages in the same gingival site where the GCF was obtained at the same time. The results suggest that macrophages in the connective tissue subjacent to the oral epithelium contribute to the production of IL-1 but those in connective tissue subjacent to the pocket epithelium play a different role in the generation of gingival inflammation.