25-Hydroxyvitamin D3 -enhanced PTPN2 positively regulates periodontal inflammation through the JAK/STAT pathway in human oral keratinocytes and a mouse model of type 2 diabetes mellitus.

BACKGROUND AND OBJECTIVE: Periodontitis is an increasingly prevalent complication of diabetes mellitus (known as diabetes mellitus-associated periodontitis), and 25-hydroxyvitamin D3 (25VD3 ) was recently found to be a critical regulator of innate immunity in this disease, but the underlying mechanisms remain poorly understood. T-cell protein tyrosine phosphatase non-receptor type 2 (PTPN2) is a potential downstream protein of the 25VD3 /vitamin D receptor pathway. The aim of this study was to investigate the regulation of PTPN2 in periodontal inflammation in diabetes mellitus-associated periodontitis. MATERIAL AND METHODS: Porphyromonas gingivalis-infected db/db mice were treated with 25VD3 . Their fasting blood glucose and body weight were monitored every other week, and the levels of alveolar bone loss and serum inflammatory cytokines (tumor necrosis factor-α, interferon-γ and interleukin-6) were determined at the time of killing. The effect of PTPN2 on human OKF6-TERT2 oral keratinocytes was examined through the knockout of PTPN2 using the CRISPR/Cas9 knockout plasmid. The expression levels of the PTPN2, vitamin D receptor and JAK1/STAT3 signaling proteins in the gingival epithelium and OKF6-TERT2 cells were determined through western blot and immunohistochemical analyses. RESULTS: After 25VD3 treatment, db/db mice exhibited alleviated serum inflammatory cytokines and alveolar bone loss, and 25VD3 -enhanced PTPN2 expression decreased the expression of the JAK1/STAT3 signaling proteins in the gingival epithelium. Analyses of human oral keratinocytes showed that 25VD3 increased the expression of PTPN2, which dephosphorylates protein substrates in the JAK1/STAT3 signaling pathway. CONCLUSION: PTPN2 contributed to a decrease in periodontal inflammation in type 2 diabetes mellitus via dephosphorylate protein substrates in the JAK1/STAT3 signaling pathway after 25VD3 treatment in human oral keratinocytes and a mouse model of type 2 diabetes mellitus. A thorough understanding of PTPN2 and its involvement in inhibiting inflammation might provide alternative therapeutic approaches for the pathogenesis and treatment of diabetes mellitus-associated periodontitis.

Biofilm removal by 6% sodium hypochlorite activated by different irrigation techniques.

AIM: To compare the removal of biofilm utilizing four irrigation techniques on a bovine root canal model. METHODOLOGY: Fifty dentine specimens (2 × 2 mm) were infected with biofilm. The samples were then adapted to previously created cavities in the bovine model. The root canals were irrigated twice with 2 mL of 6% sodium hypochlorite for 2 min (4 min total). Following initial irrigation, the different treatment modalities were introduced for 60 s (3 × 20 s intervals). The evaluated techniques were needle irrigation, Endoactivator (Dentsply Tulsa Dental, Tulsa, OK, USA), passive ultrasonic irrigation and laser-activated irrigation (photon-induced photoacoustic streaming). The controls were irrigated with distilled water and conventional needle irrigation. Subsequently, the dentine samples were separated from the model and analysed using a scanning electron microscope (SEM). Fifteen operative fields were scanned per block, and SEM pictures were captured. Two calibrated evaluators examined the images and collected data using a four-degree scale. Nonparametric tests were used to evaluate for statistical significance amongst the groups. RESULTS: The group undergoing laser-activated irrigation using photon-induced photoacoustic streaming exhibited the most favourable results in the removal of biofilm. Passive ultrasonic irrigation scores were significantly lower than both the Endoactivator and needle irrigation scores. Sonic and needle irrigation were not significantly different. The least favourable results were found in the control group. CONCLUSIONS: Laser activation of 6% sodium hypochlorite significantly improved the cleaning of biofilm-infected dentine followed by passive ultrasonic irrigation.

Experimental periodontitis induced by Porphyromonas gingivalis does not alter the onset or severity of diabetes in mice.

BACKGROUND AND OBJECTIVE: Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less evidence is available on the converse effects of periodontitis on diabetes. The objective of the study was to investigate to what degree experimental periodontitis induced by Porphyromonas gingivalis might influence the onset and severity of diabetes in different mouse models. MATERIAL AND METHODS: Twenty-eight male Tallyho/JngJ mice (type 2 diabetes), 20 male streptozotocin-induced diabetes C57BL/6J mice (type 1 diabetes) and 20 male C57BL/6J mice at 4 wks of age were evenly divided into two groups: periodontal infection and sham infection. Periodontitis was induced by Porphyromonas gingivalis W50 (P. gingivalis) oral inoculation before the development of diabetes. Sham-infected mice received vehicle as control. P. gingivalis in the oral cavity were identified by quantitative polymerase chain reaction. Fasting glucose, body weight and food intake levels were monitored and glucose tolerance tests were performed to assess glucose homeostasis for the onset and progression of diabetes. The level of alveolar bone loss and tumor necrosis factor-alpha were determined in week 20 when mice were killed. RESULTS: Mice in the infection groups developed more alveolar bone loss than those in sham-infection groups (Tallyho p = 0.021; C57-STZ p = 0.014; C57 p = 0.035). Hyperglycemic mice exhibited significantly more bone loss compared to those normal glucose mice (Tallyho vs. C57 p = 0.029; C57-STZ vs. C57 p = 0.024). The level of tumor necrosis factor-alpha was consistent with that of periodontal bone loss and hyperglycemia. There was no significant effect of mouse species on the amount of bone loss at the same level of blood glucose. No statistically significant difference or trend in glucose metabolism was found between the infection and sham-infection group. CONCLUSION: Diabetes enhanced the risk for periodontal disease induced by P. gingivalis. However, no converse impact was found between this periodontal infection and onset and severity of diabetes in both type 1 and 2 diabetes mice.

Rabbit Streptococcus pneumoniae keratitis model and topical therapy.

PURPOSE: To develop a model for experimental Streptococcus pneumoniae keratitis and to evaluate the chemotherapeutic efficacy of 12 common topical antibiotics in vivo. METHODS: Five-hundred (CFUs of log-phase S. pneumoniae were injected into the central corneal stroma of 36 eyes of 18 rabbits. After 0, 4, 8, 16, 24, and 48 hours, the in vivo growth was assayed as the CFU per cornea. Epithelial removal (to promote antibiotic entry and mimic human keratitis) was evaluated. Disc or tube dilution verification of the sensitivity or resistance of three S. pneumoniae strains was performed: a penicillin sensitive ("S"), an intermediate sensitive ("I"), and a resistant ("R") strain. Keratitis was established with S. pneumoniae "S" in 65 eyes, S. pneumoniae "I" in 107 eyes, and S. pneumoniae "R" in 78 eyes. Sixteen hours later, control corneas were harvested and the epithelium removed from treatment corneas. Every half hour saline, penicillin, gentamicin, bacitracin, ciprofloxacin, ofloxacin, erythromycin, vancomycin, ceftriaxone, cefotaxime, or chloramphenicol was applied for 5 hours. One hour later CFUs/cornea were assayed. RESULTS: After 24 hours, S. pneumoniae "S" and "I" had proliferated to 9.18+/-6.65 x 10(6) CFUs and 9.26+/-6.90 x 10(6) CFUs. Epithelial removal at 16 hours was not significant. The in vitro antibiotic sensitivity was as expected. However, in vivo, penicillin, gentamicin, or cefazolin sterilized S. pneumoniae "S." S. pneumoniae "R" responded best to fortified gentamicin with or without vancomycin; all others antibiotics were significantly less effective (P < 0.001). CONCLUSIONS: A small intracorneal S. pneumoniae inoculum in rabbit corneas grew and was maintained for 24 hours (with epithelial removal) to provide a model for testing antibiotic sensitivity in vivo. Topical penicillin is best for treating keratitis from penicillin-sensitive S. pneumoniae, whereas topical gentamicin or a combination of gentamicin and vancomycin was most effective against penicillin-resistant S. pneumoniae.

Modification of a transplantable colon tumor and immune responses in mice fed different sources of protein, fat and carbohydrate.

The effects of different sources of dietary protein, fat and carbohydrate on tumor development and on tests relating to cell-mediated immunity were investigated in male BALB/c mice after subcutaneous injection of 8 X 10(4) 1,2-dimethylhydrazine (DMH)-induced colon tumor (no. 51) cells. Results indicated that mice fed the milk protein source (especially at the low protein level) had smaller tumors, a higher spleen cell proliferative response to stimulation by phytohemagglutinin (PHA), and greater cytotoxic T-cell activity against the tumor cells than those fed the comparable diets containing protein from the other sources. Peripheral blood lymphocytes only from the milk-fed mice, regardless of tumor presence, exhibited a relatively low response to PHA stimulation, thereby suggesting a dietary effect on the migration pattern of PHA-responsive lymphocytes. The level of protein significantly affected both T-cell and natural killer cell cytotoxicity. The tumor-bearing mice fed the diet containing sucrose (table sugar) had a significantly lower spleen cell response to PHA stimulation than those fed the comparable diet containing dextrin. The level or source of fat did not significantly affect any of the parameters tested in this system.

Lack of virus transmission by the excimer laser plume.

PURPOSE: To test the possibility of pathogenic virus transmission into the operating suite during excimer laser treatment of corneal tissue. Such treatment vaporizes corneal tissue, which may put the surgeon at risk of infection from human immunodeficiency virus, hepatitis virus, or other viruses. We developed a model system to test the possibility of such virus transmission. METHODS: Pseudorabies virus is a porcine enveloped herpesvirus similar in structure and life cycle to human immunodeficiency virus and herpes simplex virus. An excimer laser was used to ablate a virus-infected tissue culture plate while an uninfected tissue culture plate was in an inverted position over the infected plate. Six hundred laser pulses were applied. Pseudorabies virus in the excimer laser plume would, potentially, contact and infect the uninfected cells. The experiment was repeated 20 times with appropriate positive and negative controls. RESULTS: None of the 20 uninfected plates was infected by the laser plume rising from ablation of infected tissue culture plates. Positive and negative controls performed as expected. CONCLUSIONS: Even under conditions designed to maximize the likelihood of virus transmission, the excimer laser ablation plume does not appear capable of transmitting this particular live enveloped virus. Excimer laser ablation of the cornea of a human immunodeficiency virus (HIV)-infected or herpesvirus-infected patient is unlikely to pose a health hazard to the surgeon.

Comparison of topical ciprofloxacin to conventional antibiotic therapy in the treatment of experimental Pseudomonas aeruginosa keratitis.

We evaluated the efficacy of topical ciprofloxacin (3.0 mg/ml) in the treatment of experimental Pseudomonas aeruginosa keratitis in 60 rabbits. We compared ciprofloxacin treatment with double drug therapy consisting of tobramycin (13.6 mg/ml) plus polymyxin B (25,000 U/ml) or carbenicillin (6 mg/L). Two strains of P. aeruginosa were used. One was a strain well characterized for use in experimental Pseudomonas keratitis (ATCC organism 27853); the second was an organism from a patient with a Pseudomonas corneal ulcer. Rabbits were treated for 16 h, after which the corneas were excised, homogenized, and plated serially for residual colony-forming units. Both organisms responded significantly better to topical off-the-shelf ciprofloxacin than to therapy with two conventional antipseudomonal fortified antibiotic drugs (p < or = 0.0001).

Retention of antimicrobial activity by human root surfaces after in situ subgingival irrigation with tetracycline HCl or chlorhexidine.

Substantivity of tetracycline HCl and chlorhexidine digluconate was assessed in extracted teeth. Fifty periodontally compromised teeth scheduled for extraction with probing depths ranging between 6 and 12 mm were root planed and then irrigated in situ with 1 of 4 solutions: tetracycline HCl at concentrations of 10 or 50 mg/ml, 0.12% chlorhexidine digluconate, or 0.9% sterile saline. Each tooth was exposed to 150 ml of the respective irrigation solution. Following extractions, the teeth were transferred to tris buffered saline and incubated at room temperature for 22 days. Incubation solutions were replaced at 24-hour intervals. Removed solutions were examined for desorbed antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Tetracycline HCl 50 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate for 12 days and greater than saline for 16 days. Tetracycline HCl 10 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate and saline for 4 days. Chlorhexidine digluconate did not exhibit any significant antimicrobial activity at any time point. Our findings demonstrate long-lasting substantivity of tetracycline HCl, but not chlorhexidine digluconate, by teeth exposed to a single episode of pocket irrigation of their periodontally-exposed roots. The amount of antimicrobial activity retained is proportional to the concentration of tetracycline HCl used for irrigation.

Antimicrobial properties of human dentin impregnated with tetracycline HCl or chlorhexidine. An in vitro study.

Substantivity of tetracycline HCl and chlorhexidine digluconate to human root dentin was assessed in vitro. 51 extracted single-rooted teeth, their crowns removed, were assigned to 1 of 4 treatments in groups of 12. A control groups included 3 roots. Each group was divided into 3 subgroups to allow evaluation of drug exposure for 1, 3 or 5 min. The roots were immersed in tetracycline HCl (10 or 50 mg/ml) or chlorhexidine digluconate (0.12 or 0.2%) solutions following root planning. Control roots were immersed in sterile saline (0.9%). Following drug immersion, the roots were transferred to tubes containing 2 ml tris buffered saline. The tubes were incubated at room temperature for 22 days. Desorption media were replaced at 24-h intervals. Removed media were examined for antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Roots immersed in tetracycline HCl 50 mg/ml released antimicrobial activity to successive desorption media for 14 days. Tetracycline HCl 10 mg/ml activity lasted 4 days. Roots subjected to chlorhexidine digluconate released antimicrobial activity for 24 h only. Within each treatment, there were no differences between the 3 exposure intervals of 1, 3 or 5 min. Our findings suggest usage of the periodontally exposed instrumented root as a depot for sustained release of tetracycline HCl, but not chlorhexidine digluconate, to the subgingival environment. The substantiveness of tetracycline HCl seems related to drug concentration rather than the exposure interval. Clinical trials are needed to confirm the clinical significance of these in vitro observations.

Efficacy of various disinfectants in killing a resistant strain of Pseudomonas aeruginosa by comparing zones of inhibition: implications for endoscopic equipment reprocessing.

OBJECTIVE: Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. METHODS: One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. RESULTS: Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I.C. Spray and Virahol had the largest mean zones of inhibition (11.33 vs 20.60 and 20.55 mm; p = 0.0001). The hypochlorite compounds Chlorox (1:10 dilution) and Dispatch had mean zones of inhibition similar to that of Cidex (11.08 and 11.25 mm vs 11.33 mm; p = not significant). The phenolic compounds OMNI II and Lysol had mean zones of inhibition smaller than that of Cidex (10.50 and 10.35 mm vs 11.33 mm; p < 0.006), and the phosphoric acid and iodine-containing IodoFive had the smallest mean zone of inhibition (9.70 vs 11.33 mm; p = 0.0001). CONCLUSIONS: The alcohol-containing disinfectants had the largest zones of inhibition against resistant P. aeruginosa. These compounds may be more effective than glutaraldehyde for endoscopic equipment reprocessing.

High-level disinfection of gastrointestinal endoscopes: are current guidelines adequate?

OBJECTIVE: For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a 6-log reduction of mycobacterial inoculum under worst case conditions. The purpose of this study was to assess the adequacy of current guidelines for high level disinfection of GI endoscopes using alkaline glutaraldehyde in simulated-use testing. METHODS: Various gastrointestinal endoscopes were contaminated with Mycobacterium chelonae in 46 experiments. Quantitative cultures were obtained from each endoscope channel separately after each step: inoculation, standardized manual cleaning, immersion in 2% glutaraldehyde (Cidex) for 10, 20, or 45 min at room temperature, 70% isopropanol rinse, and drying. RESULTS: Manual cleaning alone achieved a 4-log reduction. After 10 min of glutaraldehyde exposure, but before alcohol rinse, two of 10 experiments failed to achieve a 6-log reduction. However, after alcohol rinse, all 10 experiments achieved HLD. After 20 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. After 45 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. Thus, if the entire reprocessing protocol including manual cleaning, glutaraldehyde exposure, alcohol rinse, and drying was taken into account, the required 6-log reduction of mycobacteria was achieved with a minimum of 10 min of glutaraldehyde exposure at room temperature. CONCLUSIONS: Current guidelines for high level disinfection using glutaraldehyde are appropriate. Alcohol rinse is a valuable adjunctive step for drying and for its bactericidal effects.

Effects of dietary fat and protein on DMH-induced tumor development and immune responses.

Although in three different mouse tumor systems with corn oil as dietary fat we previously found that milk protein decreased tumor development compared with beef, the results were reversed in 1,2-dimethylhydrazine (DMH)-injected mice. The purpose of this study was to determine if the latter result was due to the protein source. BALB/c mice (n = 280) were divided into five diet groups and injected 10 times at weekly intervals with DMH (20 mg/kg wt) or saline. Four diets contained 11% protein (casein, milk, or beef) and 5% fat (corn oil or beef tallow), and the AIN-76A diet was used as a control diet. The source of fat was a significant modulator of tumor development. Corn oil markedly increased total tumor volume and the number of tumors per mouse compared with beef tallow. Its tumor-enhancing effects were evident when it was combined with milk but not with casein. In addition, significantly lower lymphoproliferation and T-cell cytotoxicity against colon tumor cell targets was associated with corn oil consumption, whereas nonfat milk as the protein source was related to normal oxidative burst capacity of phagocytes. These results demonstrate that the source of dietary fat, in addition to the protein source, has a profound effect on both tumor development and immune responsiveness in this animal tumor system.

Efficacy of high-level disinfectants for reprocessing GI endoscopes in simulated-use testing.

BACKGROUND: There has been recent public concern regarding the adequacy of current practices for flexible endoscope reprocessing. High-level disinfection is defined by the Food and Drug Administration (FDA) as a minimum of 6-log reduction of mycobacteria under a worst-case scenario. Several agents are currently approved by the FDA, but published data on their relative efficacies against mycobacteria are lacking. The objective of this study was to determine the efficacy of these agents for high-level disinfection. METHODS: In simulated-use testing, video endoscopes (5 colonoscopes and 5 duodenoscopes) were each inoculated with 9.0 x 10(7) colony-forming units of Mycobacterium chelonae. Cleaning was performed by using a standardized protocol. Each endoscope was then subjected to chemical disinfection with Cidex (2.0% glutaraldehyde) at 20 degrees C for 20 minutes, Sporox (7.5% hydrogen peroxide) at 20 degrees for 30 minutes, and Steris 20 (0.2% peracetic acid) at 50 degrees C to 56 degrees C for 12 minutes using the Steris System 1 processor. Although not FDA-approved, tests were also conducted by using 70% isopropyl alcohol at 20 degrees C for 20 minutes. These results were compared with disinfection with ethylene oxide gas. All channels were sampled for M chelonae before and after manual cleaning and after disinfection. RESULTS: Cleaning alone resulted in an average log reduction of 3. Cidex, Sporox, Steris 20, ethylene oxide gas, and isopropyl alcohol, in combination with manual cleaning, each achieved a 6-log or greater reduction of the mycobacterial inoculum. No organisms were recovered from any channel after reprocessing with ethylene oxide and Steris 20. CONCLUSIONS: Commercially available high-level disinfectants are equally efficacious for reprocessing flexible GI endoscopes when used in conjunction with cleaning and in accordance with recommended guidelines.