Accommodations for disabilities in dental education: A focus on technical standards and clinical skills.

Providing disability-based accommodations is a multifaceted process that must balance the needs of dental students and their institutions. Reasonable accommodations must not compromise patient safety or cause an undue burden on the student or institution. Therefore, more creative approaches must be considered as the number of individuals and the types of learning disabilities have increased in recent years. In the clinical setting, providing accommodations also requires detailed advanced planning and collaboration to maintain program quality. However, current technical standards (TS) may serve as a barrier to entry into the health professions for people with disabilities. These individuals remain substantially underrepresented in dentistry despite bringing unique perspectives and experiences that can contribute to a diverse workforce of culturally proficient practitioners. In response, many schools have adopted a "functional" approach to TS that emphasizes a student's abilities rather than their limitations. In addition, innovative assistive technologies coupled with the application of critical pedagogy and universal design learning practices that engage people with the widest possible range of capabilities allows equitable approaches for learning and assessment while maintaining professional standards.

The Effect of Dental Flossing Instructions and Technique on Interproximal Bleeding: A randomized control trial.

Purpose Dental floss has been promoted reduce the effects from interdental microbial biofilm, however its efficacy has been questioned in the literature. The purpose of this study was to compare daily flossing instructions using an adapted horizontal vertical flossing technique (AHVFT) and routine oral hygiene on gingival inflammation as indicated by bleeding on probing (BoP).Methods This randomized single-blinded controlled clinical trial was conducted with non-smoking adults presenting with gingivitis and no other systemic diseases. Eligible participants were recruited from a dental school patient population and were randomly assigned to one of two groups. Group A (experimental group) was instructed in how to use the AHVFT once daily and Group B (control group) was asked to continue with their regular oral hygiene practices. Clinical evaluations (interproximal BoP measurements) were performed by blinded, calibrated examiners at two, four, and eight-week intervals; the percentage of sites with interproximal BoP was recorded. Descriptive and inferential statistics were used to analyze the data.Results A total of 36 eligible participants were enrolled in the study: Group A (n=18), Group B (n=18). The mean (±SD) percentage of interproximal sites with BoP was 26.3 (±4.7), 8.6 (±7.3), 7.2 (±5.2), and 7.9 (±5.8) for Group A at baseline, two weeks, four weeks, and eight weeks, respectively. The corresponding values for Group B were 25.8 (±9.9), 15.6 (±12.4), 12.3 (±12.2), and 18.0 (±13.1), respectively. The percentage of sites with BoP was significantly lower for Group A than for Group B (p=.015 at two weeks, p=.009 at four weeks, and p<.001 at eight weeks). Within each group, the percentage of sites with BoP was significantly lower when compared with baseline (p<.008). At the final visit, the percent reduction in BoP for Group A was 70% and 30% for Group B compared with baseline. Most (88.2%) of Group A participants demonstrated mastery of the AHVFT at eight weeks.Conclusion Participants who received Instruction with the daily use of the AHVFT were shown to have reductions in interproximal BoP as compared to participants who had not received instructions in the AHVFT. Positive gingival health outcomes with dental flossing may be technique sensitive.

An In Vitro Pilot Study on the Effects of Silver Diamine Fluoride on Periodontal Pathogens and Three-Dimensional Scaffolds of Human Fibroblasts and Epithelial Cells.

Objective: The aims of this study were to investigate the antibacterial and cytotoxic effects of silver diamine fluoride (SDF) on periodontal pathogens and human skin constructs, respectively. Background: SDF has been proven to have bactericidal effects on cariogenic bacteria. No studies to date evaluated the bactericidal effects of SDF on periodontal pathogens nor its effect on epithelium and fibroblasts. Methods: Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans were cultured in monospecies biofilms, exposed to increasing concentrations of SDF and inoculated on agar plates to assess viability. Human gingival fibroblasts in 2D cultures were exposed to 1 µL of 0.394% of SDF and viewed using real-time imaging. Finally, SDF was applied to human, 3D tissue scaffolds of fibroblasts and keratinocytes, and termed human skin equivalents (HSE). A clinical dose of 38% SDF was applied, and HSE were cultured for 12 hours, 1, 3, 5, and 10 days. The tissue was observed clinically and histologically with hematoxylin and eosin staining and TUNEL. Results: S. mutans and A. actinomycetemcomitans growth was completely inhibited using all dilutions of SDF, whereas P. gingivalis was still viable with 0.197% and 0.098% of SDF. Single-layer fibroblasts experienced immediate necrosis upon contact with SDF. Application of SDF to HSE showed maturation of a whitish lesion within 24 hours, followed by pigmented, crusted tissue after 3 days. Histological evaluation of treated tissues showed apoptotic cells in the epithelium and upper half of the connective tissue. Conclusion: Our data suggest that SDF has bactericidal properties against two periodontal pathogens: P. gingivalis and A. actinomycetemcomitans. SDF caused immediate necrosis of monolayer fibroblasts, but does not extend to the full extent of layered fibroblasts in HSE.

Efficacy of an Er:YAG laser in the decontamination of dental implant surfaces: An in vitro study.

BACKGROUND: Emergence of peri-implant diseases led to the development of various methods for implant surface decontamination. This study was designed to compare the efficacy of biofilm removal from implant-like titanium surfaces by an erbium-doped yttrium-aluminum-garnet (Er:YAG) laser, titanium brush, and carbon fiber curet. METHODS: Eight study subjects were recruited. A custom mouth appliance that held eight sandblasted and acid-etched titanium discs was fabricated for each subject. Subjects were asked to wear this appliance for 72 hours to allow for biofilm development. After retrieval, discs were removed and randomized to one of four treatment groups. The discs were stained with a two-component nucleic acid dye kit, and the residual biofilm was visualized under fluorescence microscopy. Quantification of residual biofilm was performed using an image analysis software and expressed as the percentage surface area. RESULTS: Fifty-nine titanium discs were randomized to the four treatment groups. The percentage of titanium disc area covered by residual biofilm was 74.0% ± 21.6%, 32.8% ± 24.0%, 11.8% ± 10.3%, and 20.1% ± 19.2% in the control, Er:YAG, titanium brush and carbon fiber curet groups, respectively (mean ± SD). The biofilm-covered area significantly decreased in each of the three treatment groups compared with control (P < 0.008). Comparisons between treatment groups did not reveal statistical significance. CONCLUSIONS: Er:YAG laser treatment is an effective method for reducing the bacterial biofilm on titanium discs. However, on a threadless titanium surface, Er:YAG laser does not exhibit a significantly greater efficacy in biofilm removal than commonly used titanium brushes or carbon fiber curets.

Design and ex vivo characterization of narrow implants with custom piezo-activated osteotomy for patients with substantial bone loss.

OBJECTIVE: Bone augmentation delays implant placement and increases risks due to additional surgeries. Implant systems compatible with reduced alveolar bone volume are required. To design, manufacture, and test a non-cylindrical dental implant system using piezotomes and custom-designed matching titanium mini-implants to address the needs of patients with missing teeth and narrow jawbone. MATERIALS AND METHODS: Tapered mini-implants with a rectangular cross-section (4.6 mm × 2.1 mm) were machined with dimensions that could accommodate narrow alveolar ridges. The performance of the implants were tested in both static and fatigue cycle 30° compression tests. Tapered, rectangular cutting tools that matched the overall trapezoidal morphology of the implant were also designed. These novel tools were engineered to be compatible with commercially available piezoelectric osteotomes. Tools were optimized using finite element analysis and were manufactured accordingly and were used by a periodontal surgery team in a pork rib bone model to monitor utility of the device and ease of use. RESULTS: The rectangular design of the implant allows for a full occlusal load due to the larger implant flexural rigidity compared to a similar diameter mini-implant with a standard cylindrical design. During 30° compression fatigue tests, the implant tested at 340 N did not fail after 5M cycles as shown in Kaplan-Meier survival curves. Finite element analysis allowed for functional optimization of the roughing and finishing tools. In the pork rib model, these tools successfully cut trapezoidal holes that matched the dimensions of the implant. CONCLUSIONS: The implant system here demonstrates the feasibility of a mini-implant system that has superior flexural rigidity and potentially circumvents the need for patient bone augmentation.

The Effect of the Bass Intrasulcular Toothbrushing Technique on the Reduction of Gingival Inflammation: A Randomized Clinical Trial.

OBJECTIVES: The primary objective of this randomized controlled clinical trial was to investigate the effect of the Bass Intrasulcular Technique (BIT) on reducing gingival inflammation at 4 and 12 weeks compared with the toothbrushing techniques commonly used. METHODS AND MATERIALS: After receiving ethical approval from the Tufts Health Sciences Institutional Review Board, 55 subjects were invited to participate in the study. Only the subjects who presented with bleeding on probing (BoP) were enrolled. The test group (BT) was instructed on how to use the BIT, and the control group (NI) received no brushing technique instructions. Clinical measurements (probing depth, plaque score, BoP) of each tooth were recorded at 4 and 12 weeks. The toothbrushes of all participants were photographed and assessed by two blinded examiners using the ImageJ software. The statistical significance between the cohorts' BoP and their plaque score results was assessed via hierarchical logistic regression. The analyses were performed using the SAS software (version 9.4; SAS Institute, Cary, NC). RESULTS: Forty-eight participants were eligible to participate and were randomly assigned to one of the two groups (N = 24). The BT group showed significantly smaller percentages of BoP than the NI group at 4 (BT = 12.4% and NI = 31.4%) and 12 (BT = 11.6% and NI = 43.8%) weeks. The difference in plaque scores at 12 weeks was statistically significant (P = .0003) between the two groups. At 12 weeks, the Mann-Whitney U Test indicated that the difference between the groups in terms of toothbrush area was statistically significant (P = .043). CONCLUSIONS: Within the limitations of this randomized controlled clinical trial, the BIT used by participants in the BT group was significantly more effective in reducing gingival inflammation as determined by BoP than the techniques used by participants who had no instructions on brushing techniques; at 12 weeks, the BT group experienced less toothbrush deformation than the control group. CLINICAL RELEVANCE: BIT should be recommended particularly to patients exhibiting BoP and periodontal diseases.

Association between time since quitting smoking and periodontitis in former smokers in the National Health and Nutrition Examination Surveys (NHANES) 2009 to 2012.

BACKGROUND: The aims of this study were to analyze the periodontal conditions among non-smokers, former smokers and current smokers in the two National Health and Nutrition Examination Surveys (NHANES) acquired between 2009 to 2012 and determine the association between time since quitting smoking and periodontal status. METHODS: Smoking status and periodontal examination data from NHANES 2009 to 2010 and 2011 to 2012 were analyzed. Respondents included in the analysis were aged ≥18 years, had undergone a complete NHANES Oral Health - Periodontal Exam with all measurements recorded as required for the periodontal classification algorithm, and had complete data from the NHANES Smoking - Cigarette Use questionnaire. Logistic regression was conducted with time since quitting as the exposure and presence of periodontitis as the outcome, and included adjustment for confounders. RESULTS: Smoking status was significantly associated with periodontal status (Chi-square; P < 0.0001). The rate of periodontitis was highest among smokers (35%), compared with former smokers (19%) and never smokers (13%). Among former smokers, after adjusting for confounders, each additional year since quitting smoking was associated with a significant reduction in the odds ratio (OR) for periodontitis by 3.9% (OR for each year 0.961, 95% confidence interval 0.948 to 0.975). CONCLUSIONS: Among former smokers, a longer time since quitting smoking was associated with a lower likelihood of periodontitis. Consequently, dental practitioners have a public health mandate to help their patients quit smoking. Future research should determine the best strategies for facilitating smoking cessation in dental patients.

The root coverage esthetic score: Intra-examiner reliability among dental students and dental faculty.

BACKGROUND: The root coverage esthetic score (RES) was published in 2009 as an esthetic scoring system to measure visible final outcomes of root coverage procedures performed on Miller I and II recession defects. The aim of this study was to evaluate the intra-examiner, intra-group, and inter-examiner reliability of the RES when used among periodontal faculty, post-graduate students in periodontology, and pre-doctoral DMD students when using the RES at Tufts University School of Dental Medicine (TUSDM). METHODS: Thirty-three participants (12 second-year DMD students, 11 periodontal residents, and 10 faculty members) were assembled to evaluate 25 baseline and 6-month post-treatment outcomes of mucogingival surgeries using the RES. Each projection was shown for 30 seconds during which the participants were asked to use the RES scoring system to evaluate the surgical outcomes. The results were then recorded on a standardized worksheet grid. To test intra-examiner reliability, seven of the 25 projections were shown twice. Intra-examiner reliability and inter-examiner reliability were assessed using intraclass correlation coefficient using a two-way mixed effect model, and stratified by education level. RESULTS: Post-graduate (PG) residents had the highest tendency to agree with each other with an interclass correlation (ICC) of 0.53 (95% confidence interval [CI] 0.36 to 0.74). DMD students had an ICC: 0.51 (95% CI: 0.33 to 0.75), and PG faculty members produced an ICC: 0.41 (95% CI: 0.24 to 0.64). There was no statistically significant difference in ICC among the three groups of participants (Kruskal-Wallis test, P = 0.2440). When the data for each RES element were then combined, the mean ICC for the total inter-rater agreement for RES was 0.48 (95% CI: 0.32 to 0.71). This corresponds to an overall moderate agreement among all participants using the RES to evaluate the 25 surgical outcomes. The intra-examiner reliability within each of the three groups was quite high. The highest mean ICC was produced by PG faculty (0.908). The mean ICCs for PG residents was 0.867, and the mean ICC for DMD students was 0.855. The Kruskal-Wallis test (P = 0.46) failed to find any statistical difference in intra-examiner reliability among the three groups of participants. CONCLUSIONS: The RES is a "moderately" reliable scoring system for mucogingival treatments in a dental school setting and can be used even by operators with different levels of periodontal experience. This scoring system can be repeated by the same examiner to obtain reliable results.

Lack of p47(phox) in Akita Diabetic Mice Is Associated with Interstitial Pneumonia, Fibrosis, and Oral Inflammation.

Excess reactive oxygen species production is central to the development of diabetic complications. The contribution of leukocyte reactive oxygen species produced by the NADPH oxidase to altered inflammatory responses associated with uncontrolled hyperglycemia is poorly understood. To get insight into the role of phagocytic superoxide in the onset of diabetic complications, we used a model of periodontitis in mice with chronic hyperglycemia and lack of leukocyte p47(phox) (Akita/Ncf1) bred from C57BL/6-Ins2(Akita)/J (Akita) and neutrophil cytosolic factor 1 knockout (Ncf1) mice. Akita/Nfc1 mice showed progressive cachexia starting at early age and increased mortality by six months. Their lungs developed infiltrative interstitial lesions that obliterated air spaces as early as 12 weeks when fungal colonization of lungs also was observed. Neutrophils of Akita/Ncf1 mice had normal degranulation and phagocytic efficiency when compared with wild-type mice. Although Akita/Ncf1 mice had increased prevalence of oral infections and more severe periodontitis compared with wild-type mice, bone loss was only marginally higher compared with Akita and Ncf1 null mice. Altogether these results indicate that lack of leukocyte superoxide production in mice with chronic hyperglycemia results in interstitial pneumonia and increased susceptibility to infections.

The role of polyunsaturated ω-3 fatty acid eicosapentaenoic acid-derived resolvin E1 (RvE1) in bone preservation.

Resolvin E1 (RvE1) is a recently discovered lipid-derived mediator that is endogenously synthesized from the polyunsaturated fatty acid eicosapentaenoic acid. RvE1 is locally generated in response to inflammation where it enhances the resolution phase of inflammation by diminishing neutrophil chemotaxis and by enhancing nonphlogistic macrophage-directed clearance of apoptotic neutrophils. RvE1 was also found to be effective in preventing and restoring bone loss in the inflammatory bone disease periodontitis. This review examines experimental evidence on RvEl's actions in bone. Current data indicate that in addition to anti-inflammatory actions, RvE1 also directly acts on bone cells and promotes bone preservation.

B cells promote obesity-associated periodontitis and oral pathogen-associated inflammation.

Individuals with T2D and PD suffer significantly from the ability of one disease to intensify the other. Disease-associated inflammation is one mechanism thought to fuel this pathogenic feed-forward loop. Several lines of evidence indicate that proinflammatory B cells promote T2D and PD; thus, B cells are top candidates for a cell type that predisposes PD in T2D. To test directly the role of B cells in T2D-associated PD, we compared outcomes from oral Porphyromonas gingivalis challenge of lean WT or B cell-null mice with outcomes from mice that were obese and insulin-resistant before challenge. Obese WT mice responded to oral P. gingivalis challenge with significant periodontal bone loss, whereas obese B cell-null mice were protected completely from PD. By contrast, lean WT and B cell-null mice suffer similar periodontal bone loss in response to oral pathogen. B cells from obese/insulin-resistant hosts also support oral osteoclastogenesis and both oral and systemic production of inflammatory cytokines, including pro-osteoclastogenic TNF-α and MIP-2, an ortholog of human IL-8. B cells furthermore impact AT inflammation in obese, P. gingivalis-infected hosts. Taken together, these data show that fundamentally different mechanisms regulate PD in lean and obese hosts, with B cells able to promote PD only if the hosts are "primed" by obesity. These results justify more intense analysis of obesity-associated changes in B cells that predispose PD in human T2D.

Resolvin E1 regulates osteoclast fusion via DC-STAMP and NFATc1.

Interactions between the immune and skeletal systems in inflammatory bone diseases are well appreciated, but the underlying molecular mechanisms that coordinate the resolution phase of inflammation and bone turnover have not been unveiled. Here we investigated the direct actions of the proresolution mediator resolvin E1 (RvE1) on bone-marrow-cell-derived osteoclasts in an in vitro murine model of osteoclast maturation and inflammatory bone resorption. Investigation of the actions of RvE1 treatment on the specific stages of osteoclast maturation revealed that RvE1 targeted late stages of osteoclast maturation to decrease osteoclast formation by 32.8%. Time-lapse vital microscopy and migration assays confirmed that membrane fusion of osteoclast precursors was inhibited. The osteoclast fusion protein DC-STAMP was specifically targeted by RvE1 receptor binding and was down-regulated by 65.4%. RvE1 did not affect the induction of the essential osteoclast transcription factor nuclear factor of activated T cells c1 (NFATc1) or its nuclear translocation; however, NFATc1 binding to the DC-STAMP promoter was significantly inhibited by 60.9% with RvE1 treatment as shown in electrophoresis mobility shift assay. Our findings suggest that proresolution mediators act directly on osteoclasts, in addition to down-regulation of inflammation, providing a novel mechanism for modulating osteoclast signaling in osteolytic inflammatory disease.

Resolvin E1 and chemokine-like receptor 1 mediate bone preservation.

The polyunsaturated ω-3 fatty acid eicosapentaenoic acid-derived resolvin E1 (RvE1) enhances resolution of inflammation, prevents bone loss, and induces bone regeneration. Although the inflammation-resolving actions of RvE1 are characterized, the molecular mechanism of its bone-protective actions are of interest. To test the hypothesis that receptor-mediated events impact bone changes, we prepared transgenic mice overexpressing the RvE1 receptor chemokine-like receptor 1 (chemR23) on leukocytes. In zymosan-initiated peritonitis, neutrophil polymorphonuclear leukocyte infiltration in response to RvE1 was limited requiring log order lower doses in chemR23tg mice. Ligature-induced alveolar bone loss was diminished in chemR23tg mice. Local RvE1 treatment of uniform craniotomy in the parietal bone significantly accelerated regeneration of the bone defect. In in vitro bone cultures, RvE1 significantly enhanced expression of osteoprotegerin (OPG) without inducing change in receptor activator of NF-κB ligand levels, whereas the osteogenic markers alkaline phosphatase, bone sialoprotein, and Runt-related transcription factor 2 remained unchanged. These results indicate that RvE1 modulates osteoclast differentiation and bone remodeling by direct actions on bone, rescuing OPG production and restoring a favorable receptor activator of NF-κB ligand/OPG ratio, in addition to known anti-inflammatory and proresolving actions.

iNOS-derived nitric oxide stimulates osteoclast activity and alveolar bone loss in ligature-induced periodontitis in rats.

BACKGROUND: Inflammatory stimuli activate inducible nitric oxide synthase (iNOS) in a variety of cell types, including osteoclasts (OC) and osteoblasts, resulting in sustained NO production. In this study, we evaluate the alveolar bone loss in rats with periodontitis under long-term iNOS inhibition, and the differentiation and activity of OC from iNOS-knockout (KO) mice in vitro. METHODS: Oral aminoguanidine (an iNOS inhibitor) or water treatment was started 2 weeks before induction of periodontitis. Rats were sacrificed 3, 7, or 14 days after ligature placement, and alveolar bone loss was evaluated. In vitro OC culture experiments were also performed to study the differentiation of freshly isolated bone marrow cells from both iNOS KO and wild-type C57BL/6 mice. OC were counted 6 days later after tartrate-resistant acid phosphatase staining (a marker of osteoclast identity), and bone resorption activity was assessed by counting the number of resorption pits on dentin disks. RESULTS: Rats with ligature showed progressive and significant alveolar bone loss compared to sham animals, and aminoguanidine treatment significantly inhibited ligature-induced bone loss at 7 and 14 days after the induction. In comparison to bone marrow cells from wild-type mice, cells from iNOS KO mice showed decreased OC growth and the resulting OC covered a smaller culture dish area and generated fewer resorption pit counts. CONCLUSION: Our results demonstrate that iNOS inhibition prevents alveolar bone loss in a rat model of ligature-induced periodontitis, thus confirming that iNOS-derived NO plays a crucial role in the pathogenesis of periodontitis, probably by stimulating OC differentiation and activity.

Local and cardiorenal effects of periodontitis in nitric oxide-deficient hypertensive rats.

OBJECTIVE: in this study we have assessed the renal and cardiac consequences of ligature-induced periodontitis in both normotensive and nitric oxide (NO)-deficient (L-NAME-treated) hypertensive rats. MATERIALS AND METHODS: oral L-NAME (or water) treatment was started two weeks prior to induction of periodontitis. Rats were sacrificed 3, 7 or 14 days after ligature placement, and alveolar bone loss was evaluated radiographically. Thiobarbituric reactive species (TBARS; a lipid peroxidation index), protein nitrotyrosine (NT; a marker of protein nitration) and myeloperoxidase activity (MPO; a neutrophil marker) were determined in the heart and kidney. RESULTS: in NO-deficient hypertensive rats, periodontitis-induced alveolar bone loss was significantly diminished. In addition, periodontitis-induced cardiac NT elevation was completely prevented by L-NAME treatment. On the other hand L-NAME treatment enhanced MPO production in both heart and kidneys of rats with periodontitis. No changes due to periodontitis were observed in cardiac or renal TBARS content. CONCLUSIONS: in addition to mediating alveolar bone loss, NO contributes to systemic effects of periodontitis in the heart and kidney.

Untreated type 1 diabetes increases sepsis-induced mortality without inducing a prelethal cytokine response.

Diabetes mellitus is the leading comorbidity in patients with sepsis, but its impact upon survival and immunoinflammatory signaling in sepsis is undetermined. We investigated the effect of untreated diabetes mellitus upon survival and immunoinflammatory responses in the acute phase (days 1-5) of murine polymicrobial sepsis using the AKITA model of type 1 diabetes. Diabetic female C57BL/6-Ins2 (AKITA) and C57BL/6 wild-type (WT) mice underwent cecal ligation and puncture (CLP), blood (20 µL) was sampled for 5 days, and survival was monitored for 28 days. By day 5, all 8 AKITA mice died compared with 10 of 28 deaths in WT mice. Blood glucose declined post-CLP in all groups (most dramatically in AKITAs by 75%). To compare the evolution of inflammatory profiles, mice were retrospectively divided based on outcome into AKITA, WT-Died, and WT-Survived (within days 1-5). Hypoglycemia developed in all groups, which resolved in WT-Survived (97 mg/dL at 96 h) but intensified in WT-Died and AKITAs (∼30 mg/dL). Dramatic increases in both proinflammatory and anti-inflammatory cytokines were observed in WT-Died (i.e., interleukin 6, 38.2 ± 17.8 ng/mL at 24 h), which contrasted with a lack of prelethal cytokine response in AKITA mice (interleukin 6, 4.3 ± 3.4 ng/mL at 24 h). A prelethal composite cytokine score was calculated on values obtained 24 h before death. This score was 3-fold lower for proinflammatory cytokines and 6-fold lower for anti-inflammatory mediators in the AKITA mice compared with the WT-Died mice but identical to the composite score in WT-Survived. These data demonstrate that untreated type I diabetes mellitus severely exacerbates sepsis mortality without inducing a prelethal release of systemic proinflammatory or anti-inflammatory cytokines.

Chronic hyperglycemia predisposes to exaggerated inflammatory response and leukocyte dysfunction in Akita mice.

The role of polymorphonuclear neutrophils (PMN) in mediating diabetic tissue damage to the periodontium was investigated in a novel model of chronic hyperglycemia, the Akita mouse. Induction of acute peritoneal inflammation in wild-type (WT) and Akita mice resulted in exaggerated IL-6 response in Akita mice (2.9-fold increase over WT values) and a markedly increased chemokine response (KC, 2.6-fold; MCP-1, 2.6-fold; and MIP-1alpha, 4.4-fold increase over WT values). Chemotaxis to both fMLP and WKYMVm was significantly reduced in isolated Akita PMN compared with WT PMN as measured in a Boyden chamber. Superoxide release in contrast was significantly increased in Akita PMN as measured with cytochrome c reduction. Bone marrow-derived Akita PMN showed partial translocation of p47phox to the cell membrane without external stimulation, suggesting premature assembly of the superoxide-producing NADPH oxidase in hyperglycemia. In vivo studies revealed that ligature-induced periodontal bone loss is significantly greater in Akita mice compared with WT. Moreover, intravital microscopy of gingival vessels showed that leukocyte rolling and attachment to the vascular endothelium is enhanced in periodontal vessels of Akita mice. These results indicate that chronic hyperglycemia predisposes to exaggerated inflammatory response and primes leukocytes for marginalization and superoxide production but not for transmigration. Thus, leukocyte defects in hyperglycemia may contribute to periodontal tissue damage by impairing the innate immune response to periodontal pathogens as well as by increasing free radical load in the gingival microvasculature.

Mice lacking inducible nitric oxide synthase demonstrate impaired killing of Porphyromonas gingivalis.

Porphyromonas gingivalis is a primary etiological agent of generalized severe periodontitis, and emerging data suggest the importance of reactive oxygen and nitrogen species in periodontal tissue damage, as well as in microbial killing. Since nitric oxide (NO) released from inducible NO synthase (iNOS) has been shown to possess immunomodulatory, cytotoxic, and antibacterial effects in experimental models, we challenged iNOS-deficient (iNOS(-/-)) mice with P. gingivalis by using a subcutaneous chamber model to study the specific contribution of NO to host defense during P. gingivalis infection. iNOS(-/-) mice inoculated with P. gingivalis developed skin lesions and chamber rejection with higher frequency and to a greater degree than similarly challenged C57BL/6 wild-type (WT) mice. Chamber fluid from iNOS(-/-) mice possessed significantly more P. gingivalis than that of WT mice. The immunoglobulin G responses to P. gingivalis in serum was similar in WT and iNOS(-/-) mice, and the inductions of tumor necrosis factor alpha, interleukin-1 beta and interleukin-6, and prostaglandin E(2) were comparable between the two mouse strains. Although no differences in total leukocyte counts in chamber fluids were observed between iNOS(-/-) and WT mice, the percentage of dead polymorphonuclear leukocytes (PMNs) was significantly greater in iNOS(-/-) mouse chamber fluids than that of WT samples. Interestingly, casein-elicited PMNs from iNOS(-/-) mice released more superoxide than did WT PMNs when stimulated with P. gingivalis. These results indicate that modulation of superoxide levels is a mechanism by which NO influences PMN function and that NO is an important element of the host defense against P. gingivalis.

In vivo imaging of proteolytic activity in atherosclerosis.

BACKGROUND: Atherosclerotic plaque rupture, the most important cause of acute cardiovascular incidents, has been strongly associated with vascular inflammation. On the basis of the hypothesis that the inflammatory response and proteolysis lead to plaque rupture, we have examined the role of cathepsin B as a model proteolytic enzyme. METHODS AND RESULTS: Using western-type diet-fed apoE and apoE/endothelial NO synthase double knockout mice as models of atherosclerosis, we show (1) that cathepsin B is upregulated in atherosclerotic lesions characterized by high degrees of inflammation compared with normal aorta or silent lesions, (2) that intravenously injectable novel cathepsin B imaging beacons are highly activated within active atherosclerotic lesions and colocalize with cathepsin B immunoreactivity, and (3) that cathepsin B activity in atherosclerotic lesions can be imaged in whole animals by using a novel near-infrared tomographic imaging system. CONCLUSIONS: These studies indicate that cathepsin B, and potentially other proteases, may serve as a biomarker for vulnerable plaques when probed with beacons. The tomographic in vivo imaging method as well as catheter-based optical sensing methods could be readily adapted to screening and potentially to the molecular profiling of a number of proteases in vulnerable plaque in vivo.