Effects of Diabetes and Voluntary Exercise on IgA Concentration and Polymeric Immunoglobulin Receptor Expression in the Submandibular Gland of Rats.

Background and Objectives: Patients with diabetes are more susceptible to upper respiratory tract infections (URTIs) because they are easily infected. Salivary IgA (sali-IgA) levels play a major role in transmitting URTIs. Sali-IgA levels are determined by salivary gland IgA production and polymeric immunoglobulin receptor (poly-IgR) expression. However, it is unknown whether salivary gland IgA production and poly-IgR expression are decreased in patients with diabetes. While exercise is reported to increase or decrease the sali-IgA levels, it is unclear how exercise affects the salivary glands of patients with diabetes. This study aimed to determine the effects of diabetes and voluntary exercise on IgA production and poly-IgR expression in the salivary glands of diabetic rats. Materials and Methods: Ten spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (eight-week-old) were divided into two groups of five rats each: a non-exercise group (OLETF-C) and a voluntary wheel-running group (OLETF-E). Five Long-Evans Tokushima Otsuka (LETO) rats without diabetes were bred under the same conditions as the OLETF-C. Sixteen weeks after the study began, the submandibular glands (SGs) were collected and analyzed for IgA and poly-IgR expression levels. Results: IgA concentrations and poly-IgR expression levels in SGs were lower in OLETF-C and OLETF-E than in LETO (p < 0.05). These values did not differ between the OLETF-C and OLETF-E. Conclusions: Diabetes decreases IgA production and poly-IgR expression in the salivary glands of rats. Moreover, voluntary exercise increases sali-IgA levels but does not increase IgA production and poly-IgR expression in the salivary glands of diabetic rats. Increasing IgA production and poly-IgR expression in the salivary glands, which is reduced in diabetes, might require slightly higher-intensity exercise than voluntary exercise under the supervision of a doctor.

Phase locking of squeezed vacuum generated by a single-pass optical parametric amplifier.

In high-precision optical measurements, squeezed vacuum states are a promising resource for reducing the shot noise. To utilize a squeezed vacuum, it is important to lock the phase of the local oscillator (LO) to the squeezed light. The coherent control sideband (CCSB) scheme has been established for the precise phase locking, while the previous CCSB scheme was designed for the squeezed vacuum generated with an optical parametric oscillator (OPO). Thus the previous CCSB scheme is not applicable to squeezing by a single-pass optical parametric amplifier (OPA), which is attractive for generating broadband squeezed vacuum states. In this study, we propose a variant of CCSB scheme, which is applicable to the squeezing by single-pass OPA. In this scheme, we inject pump light and frequency-shifted signal light into an OPA crystal in the same way as the previous CCSB scheme. The parametric process in the OPA crystal generates a squeezed vacuum, amplifies the signal light, generates an idler light, and causes the pump depletion reflecting the interference of the amplified signal light and the idler light. Through the lock-in detection of the pump depletion, we can phase-lock the injected signal light to the pump light. Then, after the heterodyne detection of the signal and the idler light, we get the error signal of LO and realize the precise phase locking of LO to the squeezed quadrature. We show the feasibility of the proposed scheme by deriving the signal-to-noise ratio (SNR) of the modulated pump signal. We experimentally demonstrate the proposed scheme on pulsed squeezing by a single-pass OPA.

Quantum-enhanced stimulated Raman scattering microscopy in a high-power regime.

Quantum-enhanced stimulated Raman scattering (QESRS) microscopy is expected to realize molecular vibrational imaging with sub-shot-noise sensitivity, so that weak signals buried in the laser shot noise can be uncovered. Nevertheless, the sensitivity of previous QESRS did not exceed that of state-of-the-art stimulated Raman scattering (SOA-SRS) microscopes mainly because of the low optical power (3 mW) of amplitude squeezed light [Nature594, 201 (2021)10.1038/s41586-021-03528-w]. Here, we present QESRS based on quantum-enhanced balanced detection (QE-BD). This method allows us to operate QESRS in a high-power regime (>30 mW) that is comparable to SOA-SRS microscopes, at the expense of 3 dB sensitivity drawback due to balanced detection. We demonstrate QESRS imaging with 2.89 dB noise reduction compared with classical balanced detection scheme. The present demonstration confirms that QESRS with QE-BD can work in the high-power regime, and paves the way for breaking the sensitivity of SOA-SRS microscopes.

Hippocampal Subfield Volumes and Cognitive Function in Schizophrenia and Mood Disorders.

INTRODUCTION: The hippocampus is relevant to cognitive function in schizophrenia (SCZ) and mood disorder patients. Although not anatomically uniform, it is clearly divided into subfields. This study aimed to elucidate the relationship between hippocampal subfield volume and cognitive function in patients with SCZ, bipolar disorder (BP), and major depressive disorder (MDD). METHODS: The study included 21 patients with SCZ, 22 with BP, and 21 with MDD and 25 healthy controls (HCs). Neurocognitive function was assessed using the Brief Assessment of Cognition in Schizophrenia. We obtained hippocampal subfield volumes using FreeSurfer 6.0. We compared the volumes of the hippocampal subfield between the 4 groups and ascertained correlation between the cognitive composite score and hippocampal subfield volume in each group. RESULTS: The SCZ group had significantly lower cognitive composite score than the BP, MDD, and HC groups. In the SCZ group, the left and right hippocampus-amygdala transition area and right subiculum and right presubiculum volumes were significantly reduced compared to those in the HC group. The left presubiculum volumes in the SCZ group were significantly reduced compared to those in the MDD group. Subfield volumes did not significantly differ between the BP, MDD, and HC groups. Interestingly, in the SCZ group, volumes of the right CA1, right molecular layer of the hippocampus, and right granule cell and molecular layer of the dentate gyrus were significantly correlated with the cognitive composite score. CONCLUSION: Patients with SCZ had poorer cognitive function, which is related to their hippocampal pathology, than those with mood disorders.

Cognitive and functional deficits are associated with white matter abnormalities in two independent cohorts of patients with schizophrenia.

BACKGROUND: Significant evidence links white matter (WM) microstructural abnormalities to cognitive impairment in schizophrenia (SZ), but the relationship of these abnormalities with functional outcome remains unclear. METHODS: In two independent cohorts (C1, C2), patients with SZ were divided into two subgroups: patients with higher cognitive performance (SZ-HCP-C1, n = 25; SZ-HCP-C2, n = 24) and patients with lower cognitive performance (SZ-LCP-C1, n = 25; SZ-LCP-C2, n = 24). Healthy controls (HC) were included in both cohorts (HC-C1, n = 52; HC-C2, n = 27). We compared fractional anisotropy (FA) of the whole-brain WM skeleton between the three groups (SZ-LCP, SZ-HCP, HC) by a whole-brain exploratory approach and an atlas-defined WM regions-of-interest approach via tract-based spatial statistics. In addition, we explored whether FA values were associated with Global Assessment of Functioning (GAF) scores in the SZ groups. RESULTS: In both cohorts, mean FA values of whole-brain WM skeleton were significantly lower in the SCZ-LCP group than in the SCZ-HCP group. Whereas in C1 the FA of the frontal part of the left inferior fronto-occipital fasciculus (IFOF) was positively correlated with GAF score, in C2 the FA of the temporal part of the left IFOF was positively correlated with GAF score. CONCLUSIONS: We provide robust evidence for WM microstructural abnormalities in SZ. These abnormalities are more prominent in patients with low cognitive performance and are associated with the level of functioning.

Impact of Stellate Ganglion Block on Tissue Blood Flow/Oxygenation and Postoperative Mandibular Nerve Hypoesthesia: A Cohort Study.

PURPOSE: Although a stellate ganglion block (SGB) increases tissue blood flow in the mandibular region, the change in tissue oxygenation after SGB and therapeutic effect of SGB for postoperative mandibular nerve hypoesthesia remain to be established. The study aim was to measure the change in tissue oxygenation in the mandibular region after SGB. METHODS: To determine the variation in tissue oxygenation in the mandibular region, the tissue oxygen index (TOI; percentage of oxygenated hemoglobin in the total hemoglobin) was measured at the skin near the mental foramen bilaterally, at the primary site of unilateral SGB, achieved using 6 mL of 1% lidocaine hydrochloride, for the treatment of bilateral postoperative mandibular nerve injury. The primary outcome of this study is the temporal variation in TOI after SGB (0.5, 1, 5, 10, 15, 20, and 25 minutes after SGB), and the control group in this study is the TOI at the end of SGB injection (0 minute). All data are expressed as the mean ± standard deviation and 95% confidence interval (CI). Repeated-measures analysis of variance with Dunnett's test was used to determine parametric statistical significance. A P-value <.05 was considered statistically significant. RESULTS: Thirteen patients were enrolled in this study. On both the blocked and contralateral side, the TOI was significantly increased compared to that before SGB (ΔTOI at 15 minute after SGB, 5.87 ± 2.89%, P < .001, 95% CI: 4.122 to 7.617% in the blocked side, 1.88 ± 2.73%, P = .005, 95% CI: 1.877 to 2.725% in the contralateral side). CONCLUSIONS: Unilateral SGB using 6 mL of 1% lidocaine hydrochloride results in an increase in tissue oxygenation in the mandibular region. Based on these findings, we hypothesize that a series of SGBs may contribute to a more rapid recovery of postoperative trigeminal nerve injury.

Multiple comparison of different noninvasive brain stimulation and pharmacologic interventions in patients with methamphetamine use disorders: A network meta-analysis of randomized controlled trials.

AIM: In recent decades, the prevalence of amphetamine and methamphetamine use disorders has at least doubled in some regions/countries, with accompanying high risks of drug overdose-associated mortality. Noninvasive brain stimulation (NIBS) methods may be effective treatments. However, the comparative efficacy of the NIBS protocol for amphetamine/methamphetamine use disorder (AUD/MUD) remains unknown to date. The aim of this network meta-analysis (NMA) was to compare the efficacy and acceptability of various NIBS methods/protocols for AUD/MUD management. METHODS: A frequentist model-based NMA was conducted. We included randomized controlled trials (RCTs) that investigated the efficacy of NIBS and guideline-recommended pharmacologic treatments to reduce craving severity in patients with either AUD or MUD. RESULTS: Twenty-two RCTs including 1888 participants met the eligibility criteria. Compared with the sham/placebo group (study = 19, subjects = 891), a combination of intermittent theta burst stimulation over the left dorsolateral prefrontal cortex (DLPFC) and continuous TBS over the left ventromedial prefrontal cortex (study = 1, subjects = 19) was associated with the largest decreases in craving severity [standardized mean difference (SMD) = -1.50; 95% confidence intervals (95%CIs) = -2.70 to -0.31]. High-frequency repetitive transcranial magnetic stimulation over the left DLPFC was associated with the largest improvements in depression and quality of sleep (study = 3, subjects = 86) (SMD = -2.48; 95%CIs = -3.25 to -1.71 and SMD = -2.43; 95%CIs = -3.38 to -1.48, respectively). The drop-out rate of most investigated treatments did not significantly differ between groups. CONCLUSION: The combined TBS protocol over the prefrontal cortex was associated with the greatest improvement in craving severity. Since few studies were available for inclusion, additional large-scale randomized controlled trials are warranted.

Gingival blood flow before, during, and after clenching, measured by laser Doppler blood flowmeter: A pilot study.

INTRODUCTION: This study aimed to investigate the effects of the strong occlusal force on the hemodynamics of gingival microcirculation. METHODS: Eleven adult volunteers with healthy periodontium and normal occlusion participated in this study. Using a noncontact laser Doppler flowmeter placed at the attached gingiva and the interdental papilla of the maxillary first premolar, changes in gingival blood flow (GBF) were examined during and after clenching. RESULTS: When the strong occlusal pressure was applied on the maxillary first premolar by clenching, GBF in the attached gingiva on the buccal side decreased significantly compared with the resting GBF, with medians of 2.3 mL/min/100 g and 5.4 mL/min/100 g, respectively (P <0.05). After the release of the maximum clenching, GBF recovered immediately and transiently increased to a median of 2.4 mL/min/100 g, showing a significant difference to the resting GBF (P <0.05). In contrast, in the interdental papilla, no significant change in GBF was found by clenching. CONCLUSIONS: Ischemia of the buccal attached gingiva associated with strong clenching may be due to compression of the vascular network of the periodontal membrane. Through reactive hyperemia resulting from the release of clenching, it is possible not only that blood flow will be restored to the tissue but that the tissue itself may be damaged by the reperfusion. During active orthodontic treatment, it is suggested that occlusal management to prevent occlusal trauma is important to avoid detrimental effects on periodontal tissues.

Transmission properties of microwaves at an optical Weyl point in a three-dimensional chiral photonic crystal.

Microwave transmission measurements were performed for a three-dimensional (3D) layer-by-layer chiral photonic crystal (PhC), whose photonic band structure contains 3D singular points, Weyl points. For the frequency and wavevector in the vicinity of a Weyl point, the transmitted intensity was found to be inversely proportional to the square of the propagation length. In addition, the transmitted wave was well-collimated in the plane parallel to the PhC layers, even for point-source incidence. When a plane wave was incident on the PhC containing metal scatters, the planar wavefront was reconstructed after the transmission, indicating a cloaking effect.

Anisotropic light-matter coupling and below-threshold excitation dynamics in an organic crystal microcavity.

Organic semiconductors are promising candidates as platforms for room temperature polaritonic devices. An issue for practical implementation of organic polariton devices is the lowering of condensation threshold. Here we investigate anisotropic light-matter coupling characteristics in an organic crystal microcavity showing strong molecular orientation. Furthermore, the below-threshold excitation dynamics are investigated to clarify the spontaneous transition pathways from reservoir to polariton states. Time-resolved photoluminescence measurements reveal that photonic/excitonic hybrid transition processes coexist in the microcavity system. This finding provides valuable insights into a detailed understanding of polariton dynamics and help in the design of polaritonic devices showing a low-threshold condensed phase.

[Atypical clinical presentation of familial Mediterranean fever resembling colonic diverticulitis in an elderly patient:a case report].

A 69-year-old man had been intermittently experiencing abdominal pain from his 30s and was diagnosed with colonic diverticulitis. He further experienced right lower abdominal pain and received treatment. However, his condition did not improve, and he was referred to the National Defense Medical College Hospital. His abdominal pain episodes continued even after treatment for few weeks;subsequently, familial Mediterranean fever (FMF) was suspected based on the clinical course because of elevated inflammatory responses, although his body temperature was ≤38°C. After administrating colchicine as a diagnostic treatment, the repeated abdominal pain disappeared. Considering the other findings and genetic examination that showed the representative gene mutation of MEFV (M694I), he was diagnosed with FMF. This case indicates that high body temperature, one of the primary diagnostic criteria of FMF, is sometimes not evident in elderly patients, thereby causing potential misdiagnosis in some elderly patients with FMF.

Neurobiological effects of aerobic exercise, with a focus on patients with schizophrenia.

Schizophrenia is a severe neuropsychiatric disease that is associated with neurobiological alterations in multiple brain regions and peripheral organs. Negative symptoms and cognitive deficits are present in about half of patients and are difficult to treat, leading to an unfavorable functional outcome. To investigate the impact of aerobic exercise on various neurobiological parameters, we conducted a narrative review. Add-on aerobic exercise was shown to be effective in improving negative and general symptoms, cognition, global functioning, and quality of life in schizophrenia patients. Based on findings in healthy individuals and animal models, this qualitative review gives an overview of different lines of evidence on how aerobic exercise impacts brain structure and function and molecular mechanisms in patients with schizophrenia and how its effects could be related to clinical and functional outcomes. Structural magnetic resonance imaging studies showed a volume increase in the hippocampus and cortical regions in schizophrenia patients and healthy controls after endurance training. However, results are inconsistent and individual risk factors may influence neuroplastic processes. Animal studies indicate that alterations in epigenetic mechanisms and synaptic plasticity are possible underlying mechanisms, but that differentiation of glial cells, angiogenesis, and possibly neurogenesis may also be involved. Clinical and animal studies also revealed effects of aerobic exercise on the hypothalamus-pituitary-adrenal axis, growth factors, and immune-related mechanisms. Some findings indicate effects on neurotransmitters and the endocannabinoid system. Further research is required to clarify how individual risk factors in schizophrenia patients mediate or moderate the neurobiological effects of exercise on brain and cognition. Altogether, aerobic exercise is a promising candidate in the search for pathophysiology-based add-on interventions in schizophrenia.

Quantitative evaluation of light-matter interaction parameters in organic single-crystal microcavities.

Investigation of physics on light-matter interaction and strong coupling formation in organic microcavities is important to characterize the device structure enabling efficient room-temperature polariton condensation. In this study, we evaluate quantitatively the light-matter interaction parameters for three types of organic single-crystal microcavities and discuss the effects of microcavity structures on the strong coupling formation. We found that improvement in cavity quality factor causes a reduction in the photon damping constant, which results in an increase in the Rabi splitting energy. Moreover, when we used a metal thin film as the cavity mirror, it was revealed that the exciton damping became 30 times stronger than that in a dielectric mirror cavity. These experimental findings are very intriguing to achieve low-threshold or electrically pumped organic polariton devices.

High-gain and wide-band optical amplifications induced by a coupled excited state of organic dye molecules co-doped in polymer waveguide.

We investigated optical gain and lasing characteristics of a polymer thin film co-doped with Rhodamine 6G and 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye molecules. By the co-doping of these dyes, the optical gain coefficient and its spectral range were enhanced and widened, respectively. These results cannot be accounted for by the linear combination of the optical gain properties of single-doped films. Owing to this high-gain and wide-band optical amplification property, a distributed feedback lasing with a low threshold of 70 µJ/cm2 as well as a widely tunable wavelength range of 587-613 nm was achieved. We attribute this amplification property of the co-doped film, which cannot be achieved with the single-doped films, to the appearance of a coupled excited state between the two molecules.

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.

Effect of Ultraviolet Irradiation of the Implant Surface on Progression of Periimplantitis--A Pilot Study in Dogs.

OBJECTIVE: The objective of this study was to investigate morphologically the progression of periimplantitis around an ultraviolet (UV)-light-irradiated implant in dogs. MATERIALS AND METHODS: Pure titanium implants (3.3 mm in diameter and 8 mm long) were placed into dog jawbone bilaterally. Implants on one side were irradiated with UV light for 15 minutes using a photodevice immediately before placement (UV group), whereas those on the other side were not irradiated (non-UV group). Osseointegration was confirmed 90 days after implant placement by radiography. Experimental periimplantitis was induced by the application of dental floss over 90 days. Clinical and radiographic examination and micro-computed tomography (micro-CT) were performed after 90 and 180 days, and bone resorption was measured. The bone-implant interface in tissue sections was examined by light microscopy. RESULTS: Bone resorption around the UV-irradiated implant was less pronounced than around the non-UV-irradiated implant in the ligature-induced periimplantitis model. Tissue section images revealed no contact and partial destruction at the bone-implant interface. CONCLUSION: Within the limitations of this preliminary investigation, it is suggested that UV-light-irradiated implants suppress spontaneous progression of periimplantitis.

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.

Reduction of cortical excitability and increase of thalamic activity in a low-frequency rTMS treatment for chronic tinnitus.

Low-frequency repetitive transcranial magnetic stimulation (rTMS) has received increasing attention for the treatment of tinnitus, but its therapeutic mechanisms are unclear. We performed low-frequency rTMS treatment for a patient with chronic tinnitus and examined changes of cortical excitability and cerebral blood flow using paired-pulse TMS and single-photon emission computed tomography. After the rTMS treatment, tinnitus loudness was decreased, cortical excitability was reduced, and blood flow in the thalamus was increased. Our results suggest that low-frequency rTMS treatment reduces tinnitus loudness by an inhibitory effect on the cortical excitability and a remote activation effect on the thalamus through the corticothalamic networks.

Inhibitory effects of French pine bark extract, Pycnogenol®, on alveolar bone resorption and on the osteoclast differentiation.

Pycnogenol(®) (PYC) is a standardized bark extract from French maritime pine (Pinus pinaster Aiton). We examined the inhibitory effects of PYC on alveolar bone resorption, which is a characteristic feature of periodontitis, induced by Porphyromonas gingivalis (P. gingivalis) and osteoclast differentiation. In rat periodontitis model, rats were divided into four groups: group A served as the non-infected control, group B was infected orally with P. gingivalis ATCC 33277, group C was administered PYC in the diet (0.025%: w/w), and group D was infected with P. gingivalis and administered PYC. Administration of PYC along with P. gingivalis infection significantly reduced alveolar bone resorption. Treatment of P. gingivalis with 1 µg/ml PYC reduced the number of viable bacterial cells. Addition of PYC to epithelial cells inhibited adhesion and invasion by P. gingivalis. The effect of PYC on osteoclast formation was confirmed by tartrate-resistant acid phosphatase staining. PYC treatment significantly inhibited osteoclast formation. Addition of PYC (1-100 µg/ml) to purified osteoclasts culture induced cell apoptosis. These results suggest that PYC may prevent alveolar bone resorption through its antibacterial activity against P. gingivalis and by suppressing osteoclastogenesis. Therefore, PYC may be useful as a therapeutic and preventative agent for bone diseases such as periodontitis.