Contrast-enhanced CT rim sign may predict vestibular schwannoma adhesion and postoperative complications.

AIM: To investigate the clinical and radiological features to predict adhesion between vestibular schwannoma (VS) and brain tissue which is a critical risk factor for postoperative infarction and residual tumour. MATERIAL AND METHODS: One hundred and seven consecutive VS surgeries were analysed. After excluding cases without contrast-enhanced (CE) computed tomography (CT), Koos grades 1 and 2, and cases with incomplete clinical data, 44 patients were finally included in the study. Enhancement of the tumour capsule on the brainstem side on CE-CT was defined as the CE-CT rim sign, which was analysed along with clinical characteristics, including tumour adhesion and postoperative complications. RESULTS: Eight patients exhibited CE-CT rim signs; 17 had tumour adhesions. Four patients had postoperative infarction at the ipsilateral middle cerebellar peduncle; 18 exhibited postoperative infarction and/or residual tumour at the middle cerebellar peduncle. The CE-CT rim sign significantly correlated with tumour adhesion, postoperative infarction, and postoperative infarction and/or residual tumour in the cerebellar peduncle. Univariate regression analysis revealed that the CE-CT rim sign significantly correlated with tumour adhesion (odds ratio [OR] 6.81, 95% confidence interval [CI] 1.18-39.25, p=0.032) and postoperative infarction and/or residual tumour at the cerebellar peduncle (OR 6.00, 95% CI 1.04-34.31, p=0.044). CONCLUSION: The CE-CT rim sign was identified in 18.2% of patients with VS and significantly correlated with tumour adhesion and postoperative complications, such as postoperative infarction and residual tumour. This study highlights the importance of the preoperative CE-CT rim sign in VS, which is predictive of tumour adhesion and postoperative complications.

Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) associated with freshwater crabs from Kagoshima, southern Japan, with review of records of the genus from East to South Asian countries.

Temnocephalids are ectosymbionts of various freshwater animals. A species tentatively identified as Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) is reported based on materials collected from the body surface of the freshwater crabs Eriocheir japonica (Brachyura: Varunidae) and Geothelphusa exigua (Potamidae) in Kagoshima, southern Japan. The temnocephalid is characterized as follows: the cirrus composed of a cone-shaped shaft and a cylindrical introvert 42-77 µm long; the introvert covered with approximately 30 vertical rows of fine sharp spines; the four seminal receptacles; and a long, curved oviduct with vaginal gland; a pair of gland cells (Haswell's cells) present anterior to the excretory ampullae. Bayesian inference trees using partial nuclear 28S rDNA (28S) and mitochondrial cytochrome c oxidase subunit I (COI) genes supported that the specimens collected from both crab species are conspecific but these also showed the geographical variations among them on both 28S and COI. The previous records of the genus Temnosewellia in East to South Asian countries are assembled and shown on the map (fig.7, this paper).

Macrophage populations show an M1-to-M2 transition in an experimental model of coronal pulp tissue engineering with mesenchymal stem cells.

AIM: To assess M1/M2 macrophage phenotypes in a coronal pulp regeneration model in rats, under the hypothesis that there are dynamic M1/M2 phenotype changes during the different stages of the pulp regeneration. METHODOLOGY: The maxillary first molars of Wistar rats were pulpotomized, and biodegradable hydrogel-made scaffolds carrying rat bone marrow mesenchymal stem cells were implanted in the pulp chamber. After 3, 7 and 14 days, samples were processed for (i) histological analysis and double immunoperoxidase staining for CD68 (a general macrophage marker) and one of either CCR7 (an M1 marker), CD163 (an M2 marker) or CD206 (an M2 marker); (ii) real-time PCR for AIF1 (an M1 marker), CD163, CD206, IL-10 and TNF-α mRNA expression; and (iii) Western blotting for the detection of CD68, CCR7 and CD206 proteins. RESULTS: Histological analysis of the implanted region revealed sparse cellular distribution at 3 days, pulp-like tissue with a thin dentine bridge-like structure at 7 days, and dentine bridge-like mineralized tissue formation and resorption of most scaffolds at 14 days. CCR7+ macrophages had the highest density at 3 days, and then significantly decreased until 14 days (P < 0.05). In contrast, M2 marker (CD163 or CD206) expressing macrophages had the lowest density at 3 days and significantly increased until 14 days (P < 0.05). AIF1 and TNF-α mRNA levels, and CD68 and CCR7 protein levels were highest at 3 days. CD163 and CD206 mRNA levels, and CD206 protein levels increased with time and showed the highest at 14 days. IL-10 mRNA was highest at 3 days, decreased at 7 days and increased at 14 days. CONCLUSIONS: Macrophages in the regenerating pulp tissue underwent a distinct transition from M1-dominant to M2-dominant, suggesting that the M1-to-M2 transition of macrophages plays an important role in creating a favourable microenvironment necessary for pulp tissue regeneration.

Crystalline structure of pulverized dental calculus induces cell death in oral epithelial cells.

BACKGROUND AND OBJECTIVE: Dental calculus is a mineralized deposit attached to the tooth surface. We have shown that cellular uptake of dental calculus triggers nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation, leading to the processing of the interleukin-1ß precursor into its mature form in mouse and human phagocytes. The activation of the NLRP3 inflammasome also induced a lytic form of programmed cell death, pyroptosis, in these cells. However, the effects of dental calculus on other cell types in periodontal tissue have not been investigated. The aim of this study was to determine whether dental calculus can induce cell death in oral epithelial cells. MATERIAL AND METHODS: HSC-2 human oral squamous carcinoma cells, HOMK107 human primary oral epithelial cells and immortalized mouse macrophages were exposed to dental calculus or 1 of its components, hydroxyapatite crystals. For inhibition assays, the cells were exposed to dental calculus in the presence or absence of cytochalasin D (endocytosis inhibitor), z-YVAD-fmk (caspase-1 inhibitor) or glyburide (NLRP3 inflammasome inhibitor). Cytotoxicity was determined by measuring lactate dehydrogenase (LDH) release and staining with propidium iodide. Tumor necrosis factor-α production was quantified by enzyme-linked immunosorbent assay. Oral epithelial barrier function was examined by permeability assay. RESULTS: Dental calculus induced cell death in HSC-2 cells, as judged by LDH release and propidium iodide staining. Dental calculus also induced LDH release from HOMK107 cells. Following heat treatment, dental calculus lost its capacity to induce tumor necrosis factor-α in mouse macrophages, but could induce LDH release in HSC-2 cells, indicating a major role of inorganic components in cell death. Hydroxyapatite crystals also induced cell death in both HSC-2 and HOMK107 cells, as judged by LDH release, indicating the capacity of crystal particles to induce cell death. Cell death induced by dental calculus was significantly inhibited by cytochalasin D, z-YVAD-fmk and glyburide, indicating NLRP3 inflammasome involvement. In permeability assays, dental calculus attenuated the barrier function of HSC-2 cell monolayers. CONCLUSION: Dental calculus induces pyroptotic cell death in human oral epithelial cells and the crystalline structure plays a major role in this process. Oral epithelial cell death induced by dental calculus might be important for the etiology of periodontitis.

Effect of lipopolysaccharide stimulation on stem cell-associated marker-expressing cells.

AIM: To examine the effect of inflammatory stimuli on the proliferation/migration of dental pulp stem cells by assessing the responses of stem cell-associated marker-expressing cells in rat incisors to lipopolysaccharide (LPS) stimulation in vivo. METHODOLOGY: The crowns of rat incisors were removed, and the coronal pulp chamber was instrumented. After haemostasis, an absorbent point soaked in LPS was inserted into the cavity, which was then sealed. At 3, 12, and 48 h after LPS application, pulp tissues were subjected to double-immunoperoxidase labelling using two of the antibodies against microtubule-associated protein 1B (MAP1B), CD146 and STRO-1. For gene expression analysis, total RNA was extracted, and mRNA expression levels of stem cell factor (SCF), stromal-derived factor 1 (SDF-1), CD146 and MAP1B were analysed with real-time polymerase chain reaction. SCF and SDF-1 protein levels were also assessed by Western blot. Statistical analysis was performed by Kruskal-Wallis nonparametric analysis of variance, followed by Mann-Whitney U-tests with Bonferroni correction. RESULTS: The density of MAP1B+ CD146+ cells and STRO-1+ CD146+ cells in LPS-stimulated pulp tissue increased significantly at 3 h and exhibited a four- to sixfold increase at 48 h as compared with the density observed in normal pulp tissue (P < 0.05). The expression of CD146 mRNA in LPS-stimulated pulp showed significant upregulation at 3 h as compared with that observed in normal pulp tissue (P < 0.05). MAP1B, SCF and SDF-1 mRNA levels also showed significant upregulation at 3 and 72 h (P < 0.05), and Western blot analysis revealed increases in SCF and SDF-1 following LPS stimulation. CONCLUSIONS: LPS-stimulated pulp tissue exhibited upregulation of stem cell differentiation/migration markers and showed increases in the number of MAP1B+ CD146+ and STRO-1+ CD146 stem-like cells.

Directional control of diffusion and swelling in megamolecular polysaccharide hydrogels.

Directional control of diffusion and swelling in megamolecular polysaccharide hydrogels is demonstrated by focusing on the anisotropic structures for water absorption. Due to the presence of a layered structure in the hydrogel, the directional control for diffusion parallel to the planar direction and swelling in the lateral direction are possible.

Usefulness of ultrasonography in the diagnosis of ischaemic fasciitis.

We present the case of a 68-year-old woman who developed a painful subcutaneous tumour in the sacral region. Histological examinations revealed a characteristic zonal pattern with a central zone of liquefactive necrosis, surrounded by proliferated atypical fibroblasts and prominent vessels, indicating ischaemic fasciitis. We demonstrate that the characteristic features of ischaemic fasciitis revealed by ultrasonography are strongly associated with those revealed by pathological findings. We thus believe that ultrasonography is a valid tool for making an accurate diagnosis of ischaemic fasciitis.

Rutin increases critical wavelength of systems containing a single UV filter and with good skin compatibility.

BACKGROUND/PURPOSE: Ultraviolet (UV) radiation is responsible for sunburns, skin cancer, photoaging, and the production of reactive oxygen species (ROS). The awareness on preventing these deleterious effects made the use of anti-UVB formulations an important part of population habits; however, despite the availability of several antioxidants capable of ROS scavenging, the pharmaceutical market lacks products associating UV filters with natural compounds of proven efficacy. Here, we investigated the effect of rutin, a flavonoid with antioxidant activity, associated with UVB filters in dermocosmetic preparations. METHODS: Formulations were assessed through its antioxidant activity, in vitro photoprotective effectiveness, photostability, and in vivo skin tolerance (hydration, transepidermal water loss, and erythema). RESULTS: Samples containing rutin were compatible with the human skin and presented a pronounced antioxidant potential, with scavenging activity values 75% higher than the ones containing only UVB filters. Although rutin could not prevent the sunscreens photodegradation post-irradiation, the bioactive compound significantly increased the formulations critical wavelengths, showing a photoprotective gain, especially in the UVA range. CONCLUSION: In conclusion, the absorption in the UVA range, coupled with ROS scavenging potential, proved the positive effect of rutin applied to anti-UVB formulations, making this bioactive compound a promising candidate for photoprotection improvement.

Pathogenesis of acute and chronic diseases caused by cyprinid herpesvirus-3.

The pathogenesis of cyprinid herpesvirus-3 (CyHV-3) was studied using different lineages of carp/koi. After exposure to the virus, infected cells were first found in the skin by histopathology and by in situ hybridization. The epidermis of the skin was most severely damaged and often sloughed off in the fish sampled on days 5 through 8, and the fish that were highly sensitive to the virus died within 8 or 10 days after infection. Serum osmolality of the infected fish, particularly just before death, was significantly lower, suggesting that the osmotic shock consequent on the damage to the skin was the direct cause of the acute deaths. On the other hand, clinical and histopathological observations indicate that the carp of a less sensitive lineage most probably died of viral encephalitis around 3 weeks after infection. For these fish, the largest number of infected cells was found in the central nervous system (CNS) sampled on day 12. A substantial amount of viral genome was found in the CNS of carp surviving more than 1 year after the infection. Thus, the CNS is probably a major target for CyHV-3, and the virus can persistently infect the CNS, presumably establishing latency.

Order, criticality, and excitations in the extended Falicov-Kimball model.

Using exact numerical techniques, we investigate the nature of excitonic (electron-hole) bound states and the development of exciton coherence in the one-dimensional half-filled extended Falicov-Kimball model. The ground-state phase diagram of the model exhibits, besides band-insulator and staggered orbital ordered phases, an excitonic insulator (EI) with power-law correlations. The criticality of the EI state shows up in the von Neumann entropy. The anomalous spectral function and condensation amplitude provide the binding energy and coherence length of the electron-hole pairs which, on their part, point towards a Coulomb interaction driven crossover from BCS-like electron-hole pairing fluctuations to tightly bound excitons. We show that while a mass imbalance between electrons and holes does not affect the location of the BCS-BEC crossover regime, it favors staggered orbital ordering to the disadvantage of the EI. Within the Bose-Einstein condensation (BEC) regime, the quasiparticle dispersion develops a flat valence-band top, in accord with the experimental finding for Ta2NiSe5.

ROCK inhibitor Y-27632 maintains the proliferation of confluent human mesenchymal stem cells.

BACKGROUND AND OBJECTIVE: The transplantation of cell sheets of mesenchymal stem cells (MSCs) is expected to be the next generation of periodontal regenerative therapy. An adequate method of multilayering MSCs has yet to be established. When cell sheets proliferate, they usually contract and detach from culture dishes and then the proliferation of cells in the contracted areas is arrested. ROCK-mediated contractile force causes cell contraction. Although multilayer formation medium (MFM) stimulated the proliferation of growth-arrested confluent MSCs, MSCs detached from the culture dish. Therefore, we investigated the effects of ROCK inhibitor Y-27632 on the proliferation and detachment of confluent MSCs, and examined the ability of cells to differentiate within the cell sheets. MATERIAL AND METHODS: Confluent MSCs were cultured in MFM containing transforming growth factor-ß1, ascorbic acid and fetal bovine serum either with or without Y-27632. Cell proliferation was examined by bromodeoxyuridine incorporation assays and total DNA measurement. Sheet contractions were examined by light microscopy and stereomicroscopy. Multilayer formations and focal adhesion assembly were observed with confocal microscopy. Characteristic of cells were examined by flow cytometric analysis. Osteoblast lineage differentiation was observed with alkaline phosphatase and alizarin red S staining. Adipocyte lineage differentiation was observed with oil red O staining. RESULTS: The addition of Y-27632 to MFM prevented the cell sheets from detaching and did not inhibit MSC growth. The cell numbers cultured with MFM/Y-27632 were significantly higher than that obtained with MFM-only on day 4. Cell sheets detached from the culture dish on day 4, and the number of bromodeoxyuridine-positive cells in the detached area decreased. Cells in the cell sheets had similar characteristics to primary MSCs, and differentiated into osteoblast and adipocyte lineages. CONCLUSION: Y-27632 both prevented the MSC sheets from detaching and maintained the multilayered proliferation of confluent MSCs by MFM, and then cells in the sheets had differentiation potency.

Triple opportunistic pulmonary cavitary disease after cord blood transplantation.

Opportunistic infectious diseases in patients are variable and depend on the host as well as the type of immunosuppression. Cord blood transplant recipients appear to be particularly vulnerable to infectious complications. Sequential or concurrent opportunistic infectious diseases can be particularly difficult to manage and have increased mortality. We present a young patient, status post cord blood transplantation for acute myelogenous leukemia, who developed a large pulmonary mass-like infection with Aspergillus, cytomegalovirus, and Mycobacterium avium complex. Radiological, surgical, and pathological features are described.

Short-term clinical of peel-off facial mask moisturizers.

OBJECTIVE: This study aimed to compare the efficacy of a peel-off facial mask based on polyvinyl alcohol (PVA) with an oil-in-water (o/w) emulsion and the effect of a soybean extract fermented by Bifidobacterium animale incorporated in those formulations (5% w/w). METHODS: The formulations were submitted to randomized clinical studies in volunteers to evaluate the measurement effects as (a) tensor by Cutometer® , (b) moisturizing by Corneometer® and transepidermal water loss (TEWL) by Tewameter® . These effects were determined in a short-term study (3 h) in a controlled-temperature room. RESULTS: The tensor effect and TEWL values indicated no significant difference between the use of facial mask and emulsion. On the other hand, the moisturizing effect of the facial mask on the stratum corneum was more significant than that of the emulsion according to Corneometer® measurements. Biometric cutaneous evaluation of peel-off facial masks (short-term study) showed that the masks promoted moisturizing effect of the stratum corneum more effectively than the oil-in-water emulsions. Thus, the facial masks were more efficient than emulsions in relation to moisturizing effects, but this efficiency is not related to the presence of fermented soybean extract. CONCLUSION: The results indicated that peel-off facial masks increase skin hydration in a process related to the occlusive effect.

Gram-positive bacteria as an antigen topically applied into gingival sulcus of immunized rat accelerates periodontal destruction.

BACKGROUND AND OBJECTIVE: Periodontitis is generally accepted to relate to gram-negative bacteria, and the host defense system influences its onset and progression. However, little is known about the relation between gram-positive bacteria and periodontitis. In this study, we topically applied gram-positive and gram-negative bacterial suspensions to the gingival sulcus in rats after immunization, and then histopathologically examined their influence on periodontal destruction. MATERIALS AND METHODS: Rats previously immunized with heat-treated and sonicated Staphylococcus aureus or Aggregatibacter actinomycetemcomitans were used as immunized groups. The non-immunized group received only sterile phosphate-buffered saline. In each animal, S. aureus or A. actinomycetemcomitans suspension was applied topically to the palatal gingival sulcus of first molars every 24 h for 10 d. Blood samples were collected and the serum level of anti-S. aureus or anti-A. actinomycetemcomitans immunoglobulin G (IgG) antibodies was determined by enzyme-linked immunosorbent assay. The first molar regions were resected and observed histopathologically. Osteoclasts were stained with tartrate-resistant acid phosphatase (TRAP). The formation of immune complexes was confirmed by immunohistological staining of C1qB. RESULTS: Serum levels of anti-S. aureus and anti-A. actinomycetemcomitans IgG antibodies in the immunized groups were significantly higher than those in the non-immunized groups were. The loss of attachment, increase in apical migration of the junctional epithelium, and decreases in alveolar bone level and number of TRAP-positive multinuclear cells in each immunized group were significantly greater than in each non-immunized group. The presence of C1qB was observed in the junctional epithelium and adjacent connective tissue in the immunized groups. CONCLUSIONS: Heat-treated and sonicated S. aureus and A. actinomycetemcomitans induced attachment loss in rats immunized with their suspensions. Our results suggest that not only gram-negative but also gram-positive bacteria are able to induce periodontal destruction.

Cutaneous vasculitis and glomerulonephritis associated with C4 deficiency.

Complete deficiency of the fourth component of complement (C4) is an extremely rare condition. However, it has been reported that partial C4 deficiency can occur in normal subjects, and is associated with several immune diseases. We report a 44-year-old woman who developed slight oedema and punctate purpura on her lower legs after a common cold. She was noted to have persistent microscopic haematuria and proteinuria, and her C4 level was undetectable. On histological examination of a skin biopsy specimen, leucocytoclastic vasculitis was seen, with granular deposition of IgG, IgM, C3 and C1q on the vessel walls in the upper dermis. A renal biopsy showed mild mesangial proliferative glomerulonephritis with slight damage to the capillary loops, and granular deposits of IgM and C4 mainly in the mesangium. The patient was systemically well and needed no medication. The C4 level remained low during the observation period, but neither genotyping nor allotyping analysis identified a C4 deficiency.

Tactic changes in dusky frillgoby Bathygobius fuscus sneaker males: effects of body size and nest availability.

Field and laboratory studies were conducted to examine the effects of nest availability and body size on changes in male mating tactics from sneaking to nest-holding in the dusky frillgoby Bathygobius fuscus. In the field, the body size of nest-holding males decreased from early to mid-breeding season, suggesting the possibility of a change in the tactics of sneaker males to nest-holding. Many sneaker males did not use vacant spawning nests even when size-matched nests were available, but they continued to reproduce as sneakers. Similarly, in aquarium experiments with available vacant nests, some sneaker males became nest-holders irrespective of their body size, but some did not. These results showed that nest availability is not a limiting factor for changes in tactics by sneaker males in this species. Because tactic-unchanged sneaker males were co-housed with larger nest-holding males in the tanks, the body size of nearby nest-holding males may have affected the decision to change tactics for sneaker males. Moreover, smaller individuals among tactic-changed males tended to spend more time until spawning, probably because they had relatively larger costs and smaller benefits of reproduction as nest-holding males compared to larger males.

The formation of immune complexes is involved in the acute phase of periodontal destruction in rats.

BACKGROUND AND OBJECTIVE: Loss of clinical attachment and alveolar bone destruction are major symptoms of periodontitis, caused by not only the destructive effect of periodontopathic bacteria but also the overactive response of the host immune system against periodontal pathogens. The details of the participation of the immune system in the onset and progression of periodontitis are unclear. In this study, we attempted to determine whether the host immune system, and in particular the formation of immune complexes, is involved in the periodontal destruction. MATERIAL AND METHODS: We applied ovalbumin or lipopolysaccharide (LPS) as antigens and their specific immunoglobulin G (IgG) antibodies purified from rat serum to rat gingival sulcus alternately. Loss of attachment, alveolar bone destruction and the numbers of inflammatory cells infiltrating the periodontal tissue and osteoclasts on the alveolar bone surface were investigated histometrically. The formation of immune complex was confirmed by immunohistological staining of complement C1qB. RESULTS: Loss of attachment and the presence of C1qB were observed histopathologically in both experimental groups. The group that had been treated with LPS and anti-LPS IgG showed greater loss of attachment. The number of inflammatory cells in the periodontal tissue was increased in both experimental groups, while osteoclasts at the alveolar bone crest were observed only in the group that had been treated with LPS and anti-LPS IgG. CONCLUSION: In the present study, we showed that the formation of immune complex appears to be involved in the acute phase of periodontal destruction and that the biological activity of antigens is also important.

Peptidoglycan and lipopolysaccharide synergistically enhance bone resorption and osteoclastogenesis.

BACKGROUND AND OBJECTIVE: Peptidoglycan (PGN) and lipopolysaccharide (LPS) are bacterial cell wall constituents that are able to induce bone resorption by stimulating Toll-like receptor (TLR) 2 and TLR4, respectively. The fragments of PGN also stimulate inflammatory responses via nucleotide-binding oligomerization domain (NOD) 1 and NOD2, although there are differences in the NOD-stimulatory activities between gram-positive and gram-negative PGNs. The TLR and NOD signaling pathways are known to engage in cross-talk to enhance the production of inflammatory cytokines. In the present study, we investigated the effects of gram-negative and gram-positive PGNs on bone resorption and osteoclastogenesis in the presence or absence of LPS. MATERIAL AND METHODS: We injected Escherichia coli PGN or Staphylococcus aureus PGN with or without LPS into mouse gingiva, and histopathologically assessed alveolar bone resorption by tartrate-resistant acid phosphatase staining. We also stimulated osteoclast precursors from mouse bone marrow macrophages with these PGNs in vitro and assessed osteoclastogenesis. The cells were also stimulated with synthetic ligands for NOD1; γ-D-glutamyl-meso-DAP NOD2; muramyl dipeptide or TLR2; Pam(3) CSK(4) with or without LPS to analyse the signaling cross-talk. RESULTS: S. aureus PGN, but not E. coli PGN, induced alveolar bone resorption, as did LPS. However, PGN from both sources significantly enhanced the bone resorption in the mice co-injected with LPS. Both types of PGNs induced osteoclastogenesis and accelerated osteoclastogenesis when the cells were co-stimulated with LPS in vitro. All synthetic ligands synergistically induced osteoclastogenesis by co-stimulation with LPS. CONCLUSION: Gram-positive or gram-negative PGN worked synergistically with LPS to induce bone resorption and osteoclastogenesis, possibly by co-ordinating the effects of TLR2, NOD1, NOD2 and TLR4 signaling.

Topical application of lipopolysaccharide into gingival sulcus promotes periodontal destruction in rats immunized with lipopolysaccharide.

BACKGROUND AND OBJECTIVE: The causes of periodontitis are bacteria and the host immune system, but the role of the immune system in the onset and progression of periodontal disease is still unclear. Our previous report showed that the formation of an immune complex in the gingival sulcus induces periodontal destruction. This study was carried out to investigate how the immune system, particularly immunization, is involved in periodontal destruction. MATERIAL AND METHODS: Animals immunized intraperitoneally with lipopolysaccharide (LPS) were used as the immunized group. The nonimmunized group received only phosphate-buffered saline. LPS was applied daily onto the palatal gingival sulcus in both groups 1 d after the booster injection. Serum levels of anti-LPS IgG were determined. Loss of attachment and the level of alveolar bone were histopathologically and histometrically investigated. RANKL-bearing cells and the expression of C1qB were immunohistologically evaluated. RESULTS: The serum levels of anti-LPS IgG were elevated in the early experimental period in the immunized group. There were significant increases in loss of attachment, level of alveolar bone and the number of RANKL-bearing cells in the immunized group. C1qB was observed in the junctional epithelium and adjacent connective tissue. The nonimmunized group showed similar findings at and after the time when the serum level of anti-LPS IgG was elevated. CONCLUSION: Topical application of LPS as an antigen induced periodontal destruction when the serum level of anti-LPS IgG was elevated in rats immunized with LPS. The presence of C1qB suggests that the formation of immune complexes is involved in this destruction.