Bactericidal effect of hydroxyl radicals generated by the sonolysis and photolysis of hydrogen peroxide for endodontic applications.

The aim of endodontic root canal treatment is the elimination of bacteria and their products from an infected tooth root canal. To effectively disinfect a root canal, an ultrasonic irrigation system, in which hydroxyl radicals (HO·) generated artificially by sonolysis of H2O2, was developed previously for endodontic applications and was demonstrated to have bactericidal efficacy against Enterococcus faecalis. To improve this system, we examined the in vitro bactericidal effects of HO· generated from H2O2, activated by simultaneous irradiation with ultrasound for sonolysis and dental LED light for photolysis with a peak wavelength of 405 nm. Regarding the LED irradiation, two methods were used: (i) 'ideal' experimental conditions (irradiation close to the glass tube), and (ii) simulated endodontic conditions (more distant irradiation of a masked glass tube). In these conditions, HO· generation from H2O2 was detected by electron spin resonance (ESR) spectroscopy, and bactericidal efficacy against E. faecalis was assessed by measuring the colony forming units (CFU)/mL. The results indicated that HO· generation by ESR measurements and the bactericidal effect on E. faecalis by viable count using CFU/mL were enhanced significantly in a time-dependent manner in both conditions. In a comparison of these conditions, bactericidal activity under 'ideal' experimental conditions was similar to that under simulated endodontic conditions. Moreover, the irradiation time for effective killing of E. faecalis through the sonolysis and photolysis of H2O2 under simulated endodontic conditions was shorter than that with sonolysis alone. These results demonstrate that H2O2 activated by ultrasound and LED light may be a safe and effective disinfection technique for endodontic root canal treatment.

Heterologous expression of the Pleurotus ostreatus MnP3 gene by the laccase gene promoter in Lentinula edodes.

Lentinula edodes (shiitake), which have a powerful ligninolytic system, is one of the most important edible mushrooms in Asia. In this study, we introduced the manganese peroxidase (MnP, EC 1.11.1.13) gene from Pleurotus ostreatus driven by L. edodes laccase 1 gene promoter into L. edodes for expression. The resulting transformant expressed the recombinant gene and showed a higher level of MnP activity than that of the wild-type strain.

Porphyromonas gingivalis infection modifies oral microcirculation and aortic vascular function in the stroke-prone spontaneously hypertensive rat (SHRSP).

The functional modulation of vascular endothelial cells associated with stroke and periodontal disease has not yet been clarified. The objective of this study is to analyze the vascular endothelial function of periodontitis and stroke animal models. We examined endothelial function and gingival blood flow in oral microcirculation in vivo and measured the isometric tension in vitro of the aorta in animal models for lifestyle-related diseases, such as periodontitis and stroke. Gingival reactive hyperemia (GRH) was measured using laser Doppler flowmetry. Wistar Kyoto rats (WKY) were used as control animals; Porphyromonas gingivalis (P. gingivalis) infected WKY (WKY + Pg) as the periodontitis model; stroke-prone spontaneously hypertensive rat (SHRSP) as the stroke model; and a final group consisting of P. gingivalis infected SHRSP (SHRSP + Pg). Furthermore, for each group, the relaxation of descending aortic ring preparations was measured using a force transducer. The GRH was estimated by maximum response (peak), time taken for the maximum response to fall to one half (T1/2), and increased total amount of blood flow (mass). The relative change in T1/2 and mass increased in SHRSP + Pg compared to WKY. However, mass significantly increased in WKY (758.59 ± 88.21 ml/min/100 g s to 1755.55 ± 226.10 ml/min/100 g s) and SHRSP (1214.87 ± 141.61 ml/min/100 g s to 2674.32 ± 675.48 ml/min/100 g s) after treatment with acetylcholine. In addition, T1/2 and mass significantly increased in WKY + Pg (624.18 ± 96.36 ml/min/100 g s to 2629.90 ± 612.01 ml/min/100 g s) and SHRSP + Pg (1116.36 ± 206.24 ml/min/100 g s to 1952.76 ± 217.39 ml/min/100 g s) after treatment with nitroglycerin. Furthermore, the endothelium-dependent relaxation of ring preparations, evoked by acetylcholine, was attenuated in SHRSP compared with WKY, but not in SHRSP + Pg. This attenuation effect in SHRSP could be prevented by superoxide dismutase pretreatment. Our results suggest altered endothelial function may occur in gingival tissue in animal models experiencing both periodontitis and stroke. Therefore, these results indicate the disruption of vascular function in oral microcirculation may be caused by the interaction between the oxidative stress induced by periodontitis and nitric oxide in periodontitis, similar to the interactions present in stroke cases.

Protective effects of (6R)-5,6,7,8-tetrahydro-l-biopterin on local ischemia/reperfusion-induced suppression of reactive hyperemia in rat gingiva.

We herein investigated the regulatory mechanism in the circulation responsible for rat gingival reactive hyperemia (RH) associated with ischemia/reperfusion (I/R). RH was analyzed using a laser Doppler flowmeter. RH and I/R were elicited by gingival compression and release with a laser Doppler probe. RH increased in a time-dependent manner when the duration of compression was between 30 s and 20 min. This increase was significantly suppressed by N (ω)-nitro-l-arginine-methyl-ester (l-NAME), 7-nitroindazole (7-NI), and 2,4-diamino-6-hydroxypyrimidine (DAHP). However, RH was markedly inhibited following 60 min of compression. This inhibition was significantly decreased by treatments with superoxide dismutase (SOD), (6R)-5,6,7,8-tetrahydro-l-biopterin (BH4), and sepiapterin. The luminescent intensity of superoxide anion (O2 (•-))-induced 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo-[1,2-a] pyrazine-3-one (MCLA) was markedly decreased by SOD and BH4, but only slightly by sepiapterin. BH4 significantly decreased O2 (•-) scavenging activity in a time-dependent manner. These results suggested that nitric oxide (NO) secreted by the nitrergic nerve played a role in regulating local circulation in rat gingiva. This NO-related regulation of local circulation was temporarily inhibited in the gingiva by the I/R treatment. The decrease observed in the production of NO, which was caused by suppression of NO synthase (NOS) activity subsequent to depletion of the NOS co-factor BH4 by O2 (•-), played a partial role in this inhibition.

Relationship among salivary antioxidant activity, cytokines, and periodontitis: the Nagasaki Island study.

AIM: Antioxidant activities and cytokine levels in human body fluids are considered to be strongly associated with periodontitis. The aim of this study was to elucidate the relationship between salivary antioxidant activities against superoxide or hydroxyl radical, cytokines, and periodontal conditions through a community-based cross-sectional study conducted in Goto city, Japan. MATERIALS AND METHODS: Saliva samples were analysed for superoxide or hydroxyl radical scavenging activities and cytokine levels from 160 participants. We demonstrated that saliva contained superoxide and hydroxyl radical scavenging activities by using electron spin resonance with a spin-trapping agent. The concentrations of eight cytokines were measured using multiplex bead assays. RESULTS: There were significant differences in salivary superoxide or hydroxyl radical scavenging activity, and the levels of Interleukin-1ß, Interleukin-6, and Interleukin-8 between periodontitis classifications. Multivariate stepwise logistic regression model showed that salivary superoxide and hydroxyl radical scavenging activities were significantly associated with the classification of periodontitis. In addition, salivary superoxide scavenging activity was found to have significant association with all periodontal parameters using multiple linear regression analysis. CONCLUSIONS: These findings suggest that the evaluation of salivary antioxidant activities, as assessed by electron spin resonance, are associated with periodontitis and various clinical variables in community-dwelling participants (ClinicalTrials.gov number NCT01742728).

Medical-grade collagen peptide in injectables provides antioxidant protection.

Medical-grade collagen peptide is used as an additive agent in pharmaceutical formulations; however, it is unknown as to whether the compound exerts antioxidant effects in vitro. In this study, we evaluated the antioxidant effects of medical-grade collagen peptide on reactive oxygen species such as hydroxyl radical, superoxide anion radical and singlet oxygen using electron spin resonance and spin trapping. We confirmed that medical-grade collagen peptide directly inhibited hydroxyl radical generated by the Fenton reaction or by ultraviolet irradiation of hydrogen peroxide, and singlet oxygen. In addition, an antioxidant effect of medical-grade collagen peptide on singlet oxygen was observed in peptide fractions 12-22. The total amount of antioxidant amino acids (Gly, Hyp, Glu, Ala, Cys, Met and His) constituted more than half of the total amino acids in these fractions. These results suggest that the observed antioxidant properties of medical-grade collagen peptide are due to the compound containing antioxidant amino acids. Medical-grade collagen peptide, which is used in pharmaceuticals, and especially in injectables, could provide useful antioxidant properties to protect the active ingredient from oxidation.

Antimicrobial photodynamic therapy suppresses dental plaque formation in healthy adults: a randomized controlled clinical trial.

BACKGROUND: Oral care is important for oral and systemic health, especially for elderly institutionalized individuals and compromised patients. However, conventional mechanical plaque control is often difficult for these patients because of the pain or the risk of aspiration. Although antimicrobial photodynamic therapy (aPDT), which is considered an alternative or adjunct to mechanical approaches, has potential application as a less stressful method of daily plaque control, no clinical application of this technique has been reported. METHODS: We investigated the inhibitory effect of a combination of toluidine blue O (TBO), and a red light-emitting diode (LED) on dental plaque formation in healthy volunteers. The optimal concentration of TBO was determined in preliminary in vitro experiments to evaluate the bactericidal effect of aPDT on Streptococcus oralis and to clarify its safety in fibroblast cells. To survey the mechanism of TBO-mediated aPDT, the quality and quantity of reactive oxygen species (ROS) generated during aPDT were also examined using electron spin resonance (ESR) spectroscopy. Subsequently, the inhibitory effect of aPDT on dental plaque formation was investigated in eleven subjects as a clinical pilot study. The right or left mandibular premolars were randomly assigned to the treatment (with aPDT) or control (without aPDT) groups. In total, aPDT was applied six times (twice per day) to the teeth in the test group over a period of four days. On the fourth day, the study concluded and the analyses were performed. RESULTS: A combination of 500 or 1000 µg/ml TBO and LED irradiation for 20 s significantly decreased the number of colony forming units of Streptococcus oralis. The cytotoxicity of aPDT was comparable to that of standard antiseptics used in the oral cavity. Hydroxyl radicals were detected by ESR analysis, but singlet oxygen was not. A randomized controlled trial demonstrated that aPDT with 1000 µg/ml TBO and red LED irradiation significantly suppressed dental plaque formation without harming teeth or the surrounding tissues. CONCLUSIONS: aPDT has the potential to be a promising novel technical modality for dental plaque control. TRIAL REGISTRATION: This trial was registered with University Hospital Medical Information Network Clinical Trials Registry (number UMIN000012504).

Bactericidal effect of hydroxyl radicals generated from a low concentration hydrogen peroxide with ultrasound in endodontic treatment.

One approach to enhance the disinfection of root canals in endodontic treatment is ultrasonic irrigation with sodium hypochlorite. Reactive oxygen species, such as hydroxyl radical, are generated by biological defense systems to kill invading bacteria. Ultrasonic irrigation with hydrogen peroxide may be a promising option to increase hydroxyl radical generation. We examined the bactericidal effects of hydroxyl radical generated from low concentration hydrogen peroxide with ultrasound in vitro. An ultrasonic tip was submerged in 0.5 or 1.0 M hydrogen peroxide in a microfuge tube. hydrogen peroxide was irradiated with the ultrasound, the tip of which was maintained centered in the tube to mimic ultrasonic irrigation. Hydroxyl radical generation was assessed by electron spin resonance spectroscopy. Subsequently, Enterococcus faecalis suspension in hydrogen peroxide was prepared and irradiated as described above. Bactericidal effects were assessed by viable counting. Electron spin resonance measurements showed that hydroxyl radical generation increased significantly in a time- and dose-dependent manner (two-way analysis of variance and Tukey's test, p<0.05). Moreover, the bactericidal effects of hydrogen peroxide against Enterococcus faecalis were enhanced by ultrasonic irradiation in a time- and dose-dependent manner. These results suggest that ultrasonic irrigation in the presence of low concentration hydrogen peroxide can serve as a disinfection strategy in endodontic treatment.

Congenital malformations caused by Akabane virus in porcine fetuses in southern Japan.

Akabane virus (AKAV) is known as a major teratogenic agent of ruminant fetuses. In this study, we investigated the relationship between porcine abnormal deliveries and AKAV by serology, pathology, and virology investigations using specimens from 16 stillborn fetuses delivered in southern Japan between 2013 and 2015. The major clinical manifestations in stillborn fetuses were hydranencephaly, arthrogryposis, spinal curvature, and both skeletal muscle and subcutaneous edema. Histologic examination of the specimens identified atrophy of skeletal muscle fibers accompanied by adipose replacement. Nonsuppurative encephalomyelitis and decreased neuronal density in the ventral horn of the spinal cord were shown in two separate fetuses, respectively. Neutralizing antibody titers to AKAV were detected in most of the tested fetuses (13/16). The AKAV sequences detected in the affected fetuses in 2013 and 2015 were highly identical and closely related to Japanese AKAV isolates which were isolated in 2013 and sorted into genogroup I of AKAV. Immunohistochemistry visualized AKAV antigens in the neuronal cells of the central nervous system of the fetuses. These findings indicate that AKAV was involved in the birth of abnormal piglets at the affected farm. The clinical manifestations and histopathological features in the stillborn fetuses were very similar to those in ruminant neonates affected by AKAV. To avoid misdiagnosis and to evaluate the precise impact of AKAV on pig reproduction, AKAV should be considered in differential diagnoses of reproductive failures in pigs.

Anti-inflammatory potential of remimazolam: A laboratory and clinical investigation.

BACKGROUND: Anesthetic agents, particularly intravenous anesthetics, may affect immune function and tumorigenic factors. We herein investigated whether the anti-inflammatory effects of anesthetic agents are attributed to their antioxidant properties. The antioxidant and anti-inflammatory effects of remimazolam, a new anesthetic, remain unclear. We hypothesized that remimazolam exerts anti-inflammatory effects due to its antioxidant properties, which may affect the postoperative inflammatory response. This retrospective clinical study examined this hypothesis using laboratory and clinical approaches. METHODS: The antioxidant effects of remimazolam and dexmedetomidine were assessed by electron spin resonance (ESR) spectroscopy, and postoperative inflammatory responses were compared in 143 patients who underwent transcatheter aortic valve replacement at Kindai University Hospital between April 2021 and December 2022. The primary endpoint was the presence or absence of the antioxidant effects of the anesthetics themselves using ESR. RESULTS: Remimazolam at clinical concentrations exerted antioxidant effects, whereas dexmedetomidine did not. Increases in C-reactive protein (CRP) levels on POD3 from preoperative values were significantly smaller in the remimazolam group than in the dexmedetomidine group (1.33 ± 1.29 vs. 2.17 ± 1.84, p = .014). CONCLUSIONS: Remimazolam exerted stronger anti-inflammatory effects than dexmedetomidine, and these effects were enhanced by its antioxidant properties, which may have affected postoperative CRP production.

Effect of Dental Local Anesthetics on Reactive Oxygen Species: An In Vitro Study.

Introduction Oxidative stress, an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, plays an important role in various dental diseases. Local anesthetics are frequently used in dentistry. The potential antioxidant activity of dental local anesthetics can contribute to dental practice. Therefore, this study aimed to investigate the ROS-scavenging activities of three commonly used dental local anesthetics, lidocaine, prilocaine, and articaine, focusing on their effects on hydroxyl radicals (HO•) and superoxide anions (O2 •-). Materials and methods The electron spin resonance (ESR) spin-trapping technique was employed to specifically measure the ROS-scavenging activities of these local anesthetics at varying concentrations. Results Lidocaine, prilocaine, and articaine exhibited concentration-dependent HO•-scavenging activities, with IC50 values of 0.029%, 0.019%, and 0.014%, respectively. Lidocaine and prilocaine showed concentration-dependent O2 •--scavenging activity, with IC50 values of 0.033% and 0.057%, respectively. However, articaine did not scavenge O2 •-. Conclusions The proactive use of dental local anesthetics may mitigate oxidative injury and inflammatory damage through direct ROS scavenging. However, further research is needed to elucidate the specific mechanisms underlying the antioxidant effects of these dental local anesthetics and their potential impact on the dental diseases associated with oxidative stress.

Effectiveness of curcumin-based antimicrobial photodynamic therapy against Staphylococcus aureus.

PURPOSE: This study investigated the effectiveness of curcumin-based antimicrobial photodynamic therapy (aPDT) against Staphylococcus aureus (S. aureus), the causative agent of ventilator-associated pneumonia. METHODS: Curcumin was added to S. aureus culture medium at concentrations of 25, 2.5, and 0.25 µM. After 60 min (20-25°C), each culture was irradiated for 1 and 3 min, and viable bacteria were counted. Curcumin (25 µM) was also added to a bacterial suspension with D-mannitol and sodium azide; microbial counts were determined after irradiation for 3 min. RESULTS: S. aureus was significantly reduced in the 1-min (P = 0.043) and 3-min (P = 0.011) irradiation groups in comparison to the 0-min irradiation group with 25 µM curcumin. No significant differences were observed between the curcumin alone group and the curcumin plus D-mannitol or sodium azide group. CONCLUSION: The findings of this study indicate that prolonged exposure (≥1 min) of S. aureus to LED in 25 µM curcumin solution induces cell wall injury. Curcumin-based aPDT as an adjunct to conventional oral care, employing existing dentistry equipment, offers a promising approach that does not rely on antimicrobial drugs or allows the emergence of resistant bacterial strains. This suggests its potential role in future strategies aimed at preventing ventilator-associated pneumonia.

Investigation of bactericidal effect of a mid-infrared free electron laser on Escherichia coli.

The rapid increase in the number of bacteria that are resistant to many commonly used antimicrobial agents and their global spread have become a major problem worldwide. In particular, for periodontal disease, which is a localized infection, there is a growing need for treatment methods that do not primarily involve antimicrobial agents, and antimicrobial photodynamic therapy (aPDT) is attracting attention. In this study, the bactericidal effects of a mid-infrared free electron laser (MIR-FEL) on E. coli were investigated as a basic study to examine the applicability of MIR-FELs, which can selectively excite molecular vibrations due to their wavelength tunability, to aPDT. The optimal irradiation wavelengths to be examined in this study were determined from the infrared spectrum of the bacteria, which was obtained using Fourier transform infrared spectroscopy. Five irradiation wavelengths (6.62, 6.88, 7.14, 8.09 and 9.26 µm) were selected from the FT-IR spectrum, and we found that the bactericidal effects at a wavelength of 6.62 µm were markedly stronger than those observed at the other wavelengths. At this wavelength corresponding to the Amide II band, the bacterial survival rate decreased significantly as the irradiation time increased. On the contrary, irradiation of a neodymium-doped yttrium aluminum garnet (Nd: YAG) laser at 1.06 µm exhibited no distinct bactericidal effect. No morphological changes were observed after MIR-FEL irradiation, suggesting that a bacterial organelle molecule may be the target of MIR-FEL irradiation, but the exact target was not identified. Furthermore, the temperature change induced in the culture medium by the laser irradiation was ± 1.5 °C at room temperature. These results suggest that the bactericidal effects of MIR-FEL are derived from photochemical reactions involving infrared photons, since E. coli is usually killed by heating it to 75 °C for 1 min or longer.

Direct assessments of the antioxidant effects of the novel collagen peptide on reactive oxygen species using electron spin resonance spectroscopy.

In the present study, we evaluated the antioxidant effects of a pepsin-treated novel collagen peptide (P-NCP) on reactive oxygen species (ROS) such as hydroxyl radical (HO(•)), superoxide anion radical (O(2)(•-)), and singlet oxygen ((1)O(2)), and the effects on cell viability after ultraviolet ray (UV) irradiation of human fibroblasts. We confirmed, using electron spin resonance, that P-NCP directly inhibited HO(•) and (1)O(2). Furthermore, addition of P-NCP to fibroblasts inhibited cell death induced by UVA (400-315 nm) irradiation in a dose-dependent manner. In addition, the antioxidant effect on (1)O(2) was observed in the peptide fractions rich in Gly, Pro, Hyp, Glu, Ala, and Arg. We found that Gly, Hyp, Glu, and Ala directly scavenged (1)O(2). These results indicated that a peptide sequence including Gly, Hyp, Glu, and Ala could play a key role in the antioxidant effects of P-NCP on (1)O(2). It was suggested that P-NCP can inhibit photo-aging related to ROS owing to its antioxidant effects.

Direct assessment of the antioxidant properties of midazolam by electron spin resonance spectroscopy.

Some antioxidant anesthetics directly inhibit lipid peroxidation mediated via the generation of reactive oxygen species (ROS). To date, the scavenging effects of midazolam on ROS have not been directly assessed. We investigated the inhibitory effect of midazolam on ROS [hydroxyl radical (HO(·)) and superoxide (O (2) (·-) )] by in vitro X-band electron spin resonance with the spin-trapping agent 5,5-dimethyl-1-pyrroline-N-oxide. Our results indicated that HO(·) and O (2) (·-) were not affected by midazolam at clinically relevant concentrations, but were directly scavenged by midazolam at high concentrations (i.e., >4.6 and >1.5 mM, respectively).

Impact on Porphyromonas gingivalis of antimicrobial photodynamic therapy with blue light and Rose Bengal in plaque-disclosing solution.

OBJECTIVES: Antimicrobial photodynamic therapy (aPDT) in periodontal pockets using lasers is difficult to perform in some cases because of the high cost of irradiation equipment and the narrow irradiation field. The purpose of the present study was to examine the effects of aPDT in combination with a plaque-disclosing solution and blue light-emitting diode (LED), which are used for composite resin polymerization. METHODS: The reactive oxygen species generated by irradiating 0.001% RB or MB with blue light were analyzed using electron spin resonance spectroscopy. Blue-light exposure was performed at 6.92, 20.76 and 124.6 J. The microorganism to be sterilized was Porphyromonas gingivalis. After aPDT, colony-forming units (CFUs) were measured to estimate cell survival. Carbonylated protein (PC) levels were used to evaluate oxidative stress. All statistical analyses were performed with Tukey's multiple comparisons test or the unpaired t-test. RESULTS: Singlet oxygen (1O2) generation was confirmed by RB+blue LED. 1O2 production was significantly greater with the blue LED irradiation of RB than that of MB (p < 0.0001). CFUs were significantly lower in the blue LED-irradiated group than in the non-LED-irradiated group (p < 0.01). The bactericidal effect increased in a time-dependent manner. aPDT increased PC levels. No morphological changes were observed in P. gingivalis. CONCLUSIONS: The present results suggest that aPDT exerts bactericidal effects against P. gingivalis by increasing oxidative stress through the generation of 1O2 in cells. Periodontal disease may be treated by aPDT using the equipment available in dental offices.

Effect of physical stimulation (gingival massage) on age-related changes in gingival microcirculation.

The decline in circulatory function with aging may be alleviated by a combination of gingival massage (physical stimulation) and mechanical cleaning. Several studies have reported the systemic effect of physical stimulation on various parts of the body, including its therapeutic effect on pain in the neck and shoulders that becomes evident with age, and improvement in blood circulation. In contrast, few studies have reported on the changes in gingival microcirculation induced by gingival massage, while no previous study has evaluated the effect of gingival microcirculation on age-related changes in the hemodynamics of the oral cavity. This study aimed to investigate how gingival massage affects age-related changes in gingival microcirculation. Male Wistar rats (7-week, 6-month and 1-year old) were prepared for a gingival massage group and a control group. Mechanical stimulation was applied on the maxillary molar gingiva for 5 seconds twice a week for 4 weeks. Subsequently, gingival reactive hyperemia was measured using a laser Doppler flowmeter. In addition, morphological analyses were also performed by hematoxylin and eosin and Indian ink staining and a vascular resin cast model. Base Flow, maximum response (Peak), and time required for the maximum response to halve (T1/2) were reduced in 1-year-old rats compared with the other age groups. In the mechanical stimulated group, T1/2 was increased in 7-week, 6-month, and 1-year-old rats, and total blood flow (Mass) was increased in 6-month and 1-year-old rats. In addition, clear blood vessel networks and loop-like revascularization were only observed in the mechanical stimulated group. Changes in age-related decline in gingival microcirculatory function and vascular construction were reported in this study, and the results suggested that gingival massage activates both the functional and morphological aspects of gingival microcirculation and may be effective for maintaining oral health.

Antimicrobial photodynamic therapy using a plaque disclosing solution on Streptococcus mutans.

OBJECTIVES: Photodynamic therapy with a bactericidal action is called antimicrobial photodynamic therapy (aPDT),which is a method of staining an object with a photosensitizing dye and then sterilizing by irradiating the dye at it's excitation wavelength. In this study, we aimed to investigate a caries pathogenic bactericidal method in a site difficult to mechanically remove, by examining aPDT effect on Streptococcus mutans (S. mutans), which is a typical caries pathogenic bacteria by applying the plaque disclosing solution as photosensitizing dye. METHODS: The absorption wavelength spectrum of irradiating plaque staining agent phloxine B (PB) was analyzed using UV-vis. Reactive oxygen species (ROS) generated by photo excitation with blue LED irradiation was measured by electron spin resonance technique. S. mutans was cultured according to a conventional method and the effect of aPDT after PB staining was evaluated by a Colony Forming Unit (CFU). In addition, protein carbonyl (PC), an oxidative stress marker, was also measured by western blotting. RESULTS: Singlet oxygen was generated by PB with blue light. As a result of aPDT treatment on S. mutans under this condition, it was recognized that CFU was suppressed dependent on irradiation intensity of blue light. In addition, the expression of PC was enhanced by aPDT. CONCLUSIONS: aPDT is demonstrated by staining S. mutans with PB and irradiating blue light used for resin polymerization and tooth bleaching to generate ROS. Therefore, plaque-disclosing solution-based aPDT against S. mutans might represent a new method for cleaning pit and fissure grooves.

Singlet oxygen generated by a new nonthermal atmospheric pressure air plasma device exerts a bactericidal effect on oral pathogens.

Oral diseases generally have certain bacteria associated with them. Non-thermal atmospheric pressure plasma (NTAP), generated at atmospheric pressure and room temperature, incorporates several molecules, including reactive oxygen species, that can inactivate various bacteria including oral pathogens. For this reason, several NTAP devices have been developed to treat oral diseases. Use of noble gases can enhance the bactericidal efficacy of NTAP, but this requires additional gas supply equipment. Therefore, a new NTAP device that employs ambient air as the working gas was developed. The device generates non-thermal atmospheric pressure air plasma. Here, the singlet oxygen (1O2) levels generated, their bactericidal effects on oral pathogens (Streptococcus mutans, Porphyromonas gingivalis, and Enterococcus faecalis), and the bacterial oxidative stress they imposed were measured. 1O2 generation in phosphatebuffered saline was assessed qualitatively using electron spin resonance (ESR) spectroscopy, and bactericidal efficacy was evaluated by counting of colony-forming units/mL. Bacterial oxidative stress was determined by measurement of hydrogen peroxide (H2O2) and superoxide dismutase (SOD) activity. ESR indicated that the level of 1O2 increased significantly and time-dependently, and was inversely correlated with distance, but the bactericidal effects were correlated only with treatment time (not distance) as H2O2 increased and SOD levels decreased, suggesting that the new device has potential applicability for treatment of oral disease.

Direct assessments of the antioxidant effects of propofol medium chain triglyceride/long chain triglyceride on the brain of stroke-prone spontaneously hypertensive rats using electron spin resonance spectroscopy.

BACKGROUND: Antioxidant anesthetics such as propofol (2,6-diisopropylphenol) directly inhibit lipid peroxidation via the generation of reactive oxygen species. Currently, there are no other studies regarding the direct effects of propofol medium chain triglyceride/long chain triglyceride (MCT/LCT) on reactive oxygen species generation or in experimental models of reactive oxygen species-induced oxidative stress in the brain. METHODS: The authors investigated the effects of propofol MCT/LCT on reactive oxygen species (hydroxyl radical or superoxide) by electron spin resonance spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide. The effects of propofol MCT/LCT on oxidative stress in the brain of Wistar-Kyoto rats or stroke-prone spontaneously hypertensive rats were investigated by using an in vivo L-band electron spin resonance system to monitor the decay rate of 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl as a nitroxyl spin probe. RESULTS: These studies provided direct evidence that propofol MCT/LCT inhibited hydroxyl radical generation, but not superoxide generation. Regarding the hydroxyl radical from the Fenton system, it is likely to be due to the scavenging effects of vehicle. Anesthesia with propofol MCT/LCT reduced the degree of the high oxidative stress in the brain of stroke-prone spontaneously hypertensive rats. CONCLUSION: The current data show that propofol, mixed with clinical reagents (propofol MCT/LCT), resulted in the down-regulation of high oxidative stress due to scavenging hydroxyl radical, as demonstrated by in vitro or in vivo electron spin resonance analysis. These results led to reduced levels of hydroxyl radical, formed by brain injury such as stroke, and may therefore provide advantages for neuroprotection during anesthesia for craniotomy, e.g., in cases of brain disease.