Hiding from heat: The transcriptomic response of two clam species is modulated by behaviour and habitat.

Rising occurrence of extreme warming events are profoundly impacting ecosystems, altering their functioning and services with significant socio-economic consequences. Particularly susceptible to heatwaves are intertidal shellfish beds, located in estuarine areas already stressed by factors such as rainfall events, red tides, eutrophication, and pollution. In Galicia, Northwestern Spain, these beds support vital shellfisheries, featuring the native clam Ruditapes decussatus and the non-indigenous R. philippinarum. Over recent decades, these populations have experienced notable abundance shifts due to various anthropogenic impacts, including climate change. In this habitat, patches of the seagrass Zostera noltei that coexist with bare sand can act as thermal refuges for benthic organisms such as clams. To assess the impact of heatwaves on these ecosystems, a mesocosm experiment was conducted. Juveniles of both clam species in two habitat types-bare sand and sand with Z. noltei-were exposed to simulated atmospheric heatwaves during diurnal low tide for four consecutive days. Subsequent transcriptomic analysis revealed that high temperatures had a more pronounced impact on the transcriptome of R. philippinarum compared to R. decussatus. The habitat type played a crucial role in mitigating heat stress in R. philippinarum, with the presence of Z. noltei notably ameliorating the transcriptomic response. These findings have direct applications in shellfishery management, emphasizing the importance of preserving undisturbed patches of Z. noltei as thermal refuges, contributing to the mitigation of heatwave effects on shellfish populations.

Probiotic Lactobacillus Rhamnosus GG Protects Against P. Gingivalis And F. Nucleatum Gut Dysbiosis.

OBJECTIVES: This study investigated changes induced by Porphyromonas gingivalis and on gastrointestinal histology and gut microbiome in a mouse model of experimental periodontitis. The effect of probiotic Lactobacillus rhamnosus GG (LGG) in altering these changes was also investigated. METHODS: IThirty-six mice were allocated into six groups. Experimental alveolar bone loss was induced by oral inoculation with P. gingivalis and F. nucleatum. LGG was orally inoculated or orally gavaged. Gastrointestinal tissue changes were assessed using histological analysis and immunohistochemistry. Caecal microbiome was analysed by sequencing 16S rRNA genes of caecal content. RESULTS: Inoculation with P. gingivalis and F. nucleatum induced inflammation throughout gastrointestinal tract (p less than 0.05), increased expression of IL-6 in ileum (p = 0.052) and altered composition of caecal microbiome (p less than 0.05) in experimental mice compared to controls. Mice treated with LGG had reduced tissue inflammation in duodenum (p = 0.044) and lowered levels of IL-6 in ileum (p = 0.048) when compared with disease. LGG therapy influenced gut microbiome changes. CONCLUSION: P. gingivalis and F. nucleatum inoculation induced significant changes in intestinal inflammation and caecal microbiome. Oral gavage with LGG exerted a protective effect against intestinal inflammation and limited gut microbiome changes associated with P. gingivalis and F. nucleatum.

Probiotic Lactobacillus rhamnosus GG prevents alveolar bone loss in a mouse model of experimental periodontitis.

AIM: This study investigated the role of Lactobacillus rhamnosus GG (LGG) on bone loss and local and systemic inflammation in an in vivo mouse model of experimental periodontitis (PD). MATERIALS AND METHODS: Experimental PD was induced in mice by oral inoculation with Porphyromonas gingivalis and Fusobacterium nucleatum over a period of 44 days. The probiotic LGG was administered via oral inoculation or oral gavage prior to, and during disease induction. The antimicrobial activity of LGG on the inoculum was also tested. Alveolar bone levels and gingival tissue changes were assessed using in vivo microcomputed tomography and histological analysis. Serum levels of mouse homologues for IL-8 were measured using multiplex assays. RESULTS: Pre-treatment with probiotics either via oral gavage or via oral inoculation significantly reduced bone loss (p < .0001) and gingival inflammation (p < .0001) when compared with PD group. Oral gavage treatment group had significantly less tartrate-resistant acid phosphatase positive cells (p < .02) then PD group. LGG showed no antimicrobial activity against P. gingivalis and F. nucleatum. CONCLUSIONS: Lactobacillus rhamnosus GG effectively suppresses bone loss in a mouse model of induced PD irrespective of the mode of administration.

Mixed effects of caffeic acid phenethyl ester (CAPE) on joint inflammation, bone loss and gastrointestinal inflammation in a murine model of collagen antibody-induced arthritis.

OBJECTIVE: To investigate the effect of caffeic acid phenethyl ester (CAPE) on local and systemic inflammation and bone loss in collagen antibody-induced arthritis (CAIA) mice. METHODS: Four groups of mice (n = 8 per group) were allocated; control, CAPE (1 mg/kg), CAIA and CAIA + CAPE (1 mg/kg). Local inflammation and bone loss were evaluated using clinical paw scores, in vivo micro-computed tomography (micro-CT), histological assessment and tartrate-resistant acid phosphatase (TRAP) staining. Serum levels of C-reactive protein (CRP) and C-terminal telopeptide (CTX-1) were measured by ELISA. Jejunum and colon sections were evaluated histopathologically for damage and toxicity. RESULTS: Greater paw scores and percentage change in paw volume were observed in CAIA + CAPE compared to the control groups (p < 0.05). Bone volume over time remained unchanged (p = 0.94) and the number of multinucleated TRAP-positive cells was greatest in CAIA + CAPE mice (p < 0.05). CRP and CTX-1 levels did not differ between groups. CAIA + CAPE mice exhibited lower colon toxicity scores and a reduced percentage of cavitated goblet cells in the colon crypts compared with CAIA mice (p = 0.026 and p = 0.003, respectively). Histopathology in the jejunum was not altered. CONCLUSION: CAPE did not reduce paw inflammation or bone loss in CAIA mice. CAPE reduced histopathological changes in the colon of CAIA mice.

Investigation of the Cell Surface Proteome of Human Periodontal Ligament Stem Cells.

The present study examined the cell surface proteome of human periodontal ligament stem cells (PDLSC) compared to human fibroblasts. Cell surface proteins were prelabelled with CyDye before processing to extract the membrane lysates, which were separated using 2D electrophoresis. Selected differentially expressed protein "spots" were identified using Mass spectrometry. Four proteins were selected for validation: CD73, CD90, Annexin A2, and sphingosine kinase 1 previously associated with mesenchymal stem cells. Flow cytometric analysis found that CD73 and CD90 were highly expressed by human PDLSC and gingival fibroblasts but not by keratinocytes, indicating that these antigens could be used as potential markers for distinguishing between mesenchymal cells and epithelial cell populations. Annexin A2 was also found to be expressed at low copy number on the cell surface of human PDLSC and gingival fibroblasts, while human keratinocytes lacked any cell surface expression of Annexin A2. In contrast, sphingosine kinase 1 expression was detected in all the cell types examined using immunocytochemical analysis. These proteomic studies form the foundation to further define the cell surface protein expression profile of PDLSC in order to better characterise this cell population and help develop novel strategies for the purification of this stem cell population.

Evaluation of Hydroxyl Radical Diffusion and Acidified Thiourea as a Scavenger during Intracoronal Bleaching.

INTRODUCTION: The diffusion of hydroxyl radicals in intracoronal bleaching is associated with a risk of invasive cervical resorption. The use of acidified thiourea has been recommended as a scavenger of residual radicals generated during intracoronal bleaching. The aims of this study were to quantify hydroxyl radical diffusion to external root surfaces after intracoronal bleaching with commonly used materials and to evaluate the effect of using acidified thiourea with hydrogen peroxide (H2O2) on hydroxyl radical diffusion. METHODS: Eighty-two human premolars were prepared, stained, root filled, and allocated to experimental and control groups as follows: group 1: sodium perborate (SP) and water (n = 21), group 2: H2O2 (n = 21), group 3: acidified thiourea and H2O2 (n = 21), group 4: neutral thiourea and H2O2 (n = 10), control group 1: negative control (water) (n = 10), and control group 2: positive control (SP and H2O2) (n = 10). Materials were placed into the pulp chamber, sealed, and placed in 5 mmol/L terephthalic acid at 37°C for 48 hours. Hydroxyl radicals were quantified using a fluorescence microplate reader and high-performance liquid chromatography with fluorescence detection. RESULTS: The H2O2 and SP mixture resulted in the greatest hydroxyl radical diffusion and was significantly greater than SP and water (P < .05) and H2O2 (P < .05). The addition of acidified thiourea resulted in higher radical diffusion, whereas the addition of neutral thiourea resulted in lower diffusion than H2O2 alone. CONCLUSIONS: The SP and water mixture resulted in the lowest hydroxyl radical diffusion, and the H2O2 and SP mixture resulted in the greatest. Although the addition of acidified thiourea to H2O2 did not reduce radicals detected, the addition of neutral thiourea had a positive effect.

A preclinical dental trauma teaching module.

A dental trauma exercise using the anterior segment of a sheep mandible as a model has been incorporated into the undergraduate dental programme at the University of Adelaide since 2011. Students are required to replant a simulated tooth avulsion, reposition a laterally luxated tooth injury and then apply a flexible splint consisting of 40 lb fishing nylon attached with a resin-modified glass ionomer cement, GC Fuji Ortho LC. The exercise concludes with the simple removal of the splint with a spoon excavator. The acrylic mounted formalin-fixed sheep mandible is reusable, which has obvious economic and practical advantages.

The X-Linked Inhibitor of Apoptosis Protein Inhibitor Embelin Suppresses Inflammation and Bone Erosion in Collagen Antibody Induced Arthritis Mice.

OBJECTIVE: To investigate the effect of Embelin, an inhibitor of X-Linked Inhibitor of Apoptosis Protein (XIAP), on inflammation and bone erosion in a collagen antibody induced arthritis (CAIA) in mice. METHODS: Four groups of mice (n = 6 per group) were allocated: CAIA untreated mice, CAIA treated with Prednisolone (10 mg/kg/day), CAIA treated with low dose Embelin (30 mg/kg/day), and CAIA treated with high dose Embelin (50 mg/kg/day). Joint inflammation was evaluated using clinical paw score and histological assessments. Bone erosion was assessed using micro-CT, tartrate resistant acid phosphatase (TRAP) staining, and serum carboxy-terminal collagen crosslinks (CTX-1) ELISA. Immunohistochemistry was used to detect XIAP protein. TUNEL was performed to identify apoptotic cells. RESULTS: Low dose, but not high dose Embelin, suppressed inflammation as reflected by lower paw scores (P < 0.05) and lower histological scores for inflammation. Low dose Embelin reduced serum CTX-1 (P < 0.05) and demonstrated lower histological score and TRAP counting, and slightly higher bone volume as compared to CAIA untreated mice. XIAP expression was not reduced but TUNEL positive cells were more abundant in Embelin treated CAIA mice. CONCLUSION: Low dose Embelin suppressed inflammation and serum CTX-1 in CAIA mice, indicating a potential use for Embelin to treat pathological bone loss.

Parthenolide reduces empty lacunae and osteoclastic bone surface resorption induced by polyethylene particles in a murine calvarial model of peri-implant osteolysis.

The study aimed to determine the effects of parthenolide (PAR) on bone volume (BV) and bone surface resorption as assessed by live-animal microcomputed tomography (µCT) and possible osteocyte death as indicated by empty lacunae histologically in polyethylene (PE) particle-induced calvarial osteolysis in mice. Baseline µCT scans were conducted 7 days preimplantation of 2 × 10(8) PE particles/mL over the calvariae (day 0). PAR at 1 mg/kg/day was subcutaneously injected on days 0, 4, 7, and 10. At day 14, BV and surface resorption was analyzed with µCT. Calvarial tissue was processed for histomorphometric osteocyte evaluation. Serum was analyzed for type-1 carboxy-terminal collagen crosslinks (CTX-1) and osteoclast associated receptor (OSCAR) levels by ELISA. PE significantly decreased BV (p = 0.0368), increased surface bone resorption area (p = 0.0022), and increased the percentage of empty lacunae (p = 0.0043). Interestingly, PAR significantly reduced the resorption surface area (p = 0.0022) and the percentage of empty osteocyte lacunae (p = 0.0087) in the PE-calvariae, but it did not affect BV, serum CTX-1 or OSCAR levels. The ability of PAR to inhibit PE-induced surface bone erosion may better reflect the in vivo situation, where bone resorption occurs on the surface at the bone-implant interface and may also be related to the role of osteocytes in this pathology.

Inhibiting histone deacetylase 1 suppresses both inflammation and bone loss in arthritis.

OBJECTIVE: Histone deacetylase 1 (HDAC1) is highly expressed in the synovium of RA patients. Thus we aimed to investigate a novel HDAC inhibitor (HDACi), NW-21, designed to target HDAC1. The effect of NW-21 on osteoclast formation and activity, cytokine and chemokine expression in vitro and arthritis in mice was assessed. METHODS: The effects on human osteoclast formation and activity derived from human blood monocytes stimulated with receptor activator of nuclear factor κB ligand (RANKL) and M-CSF were assessed. The anti-inflammatory activity of NW-21 was assessed using human monocytes stimulated with either TNF-α or lipopolysaccharide for 24 h. mRNA expression of monocyte chemotactic protein 1 (MCP-1), TNF-α, macrophage inflammatory protein 1α (MIP-1α), IL-1 and RANTES (regulated on activation, normal T cell expressed and secreted) was assessed. The effect of NW-21 in the collagen antibody-induced arthritis model was assessed following daily oral administration at 5 mg/kg/day. The HDAC1 inhibitors NW-21 and MS-275 were compared with a broad-acting HDACi, 1179.4b. Effects on inflammation and bone were assessed using paw inflammation scoring, histology and live animal micro-CT. RESULTS: NW-21 suppressed osteoclast formation and activity as well as significantly reducing mRNA expression of MCP-1 and MIP-1α in monocytes stimulated by lipopolysaccharide or TNF-α (P < 0.05) in vitro. Only inhibitors that targeted HDAC1 (NW-21 and MS-275) reduced inflammation and bone loss in the arthritis model. CONCLUSION: The results indicate that inhibitors targeting HDAC1, such as NW-21 and MS-275, may be useful for treating RA, as such drugs can simultaneously target both inflammation and bone resorption.

Pharmacological actions of thymol and an analogue at GABAB autoreceptors.

GABAB autoreceptors inhibit release of GABA from GABAergic nerve terminals. Agonists of these receptors (e.g. baclofen) inhibit, whereas antagonists (e.g. (+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid; Sch 50911) enhance release of the transmitter. The actions of thymol (2-isopropyl-5-methylphenol) and the structurally related compound 2-tert-butyl-4-methylphenol, (4MP) on the release of [(3) H]-GABA were examined in rat neocortical slices where the GABAergic nerves had been preloaded with [(3) H]-GABA and subsequently stimulated electrically on two occasions (S1 and S2 ). Test agents, baclofen and Sch 50911 were added to the superfusion medium prior to the second period of stimulation (S2 ). Stimulation-induced overflow (SIO) of [(3) H]-GABA as a consequence of these stimulations (SIO1 and SIO2 ) were calculated and the effects of agents determined by comparing the SIO2 /SIO1 ratio in the presence of each agent with that in control tissue. Thymol potentiated the release of [(3) H]-GABA (EC50 170 µmol/L), an action reversed by baclofen (2 µmol/L). Baclofen alone had little effect on GABA release. Release of [(3) H]-GABA was inhibited by 4MP (IC50 3 µmol/L) and this effect was blocked by Sch 50911 (10 µmol/L). Alone, Sch 50911 markedly potentiated the release of GABA. These results imply that 4MP is an agonist of GABAB autoreceptors; however, further studies are needed to confirm that thymol is indeed a GABAB autoreceptor antagonist. Of interest are structural differences in these agents. Thymol has a propyl group in the ortho position relative to the phenolic hydroxyl, whereas in 4MP this is a butyl group and the methyl group moves from position 5 to 4. Whether one or both of these changes was responsible for the above actions is unknown.

Porphyromonas gingivalis peptidylarginine deiminase, a key contributor in the pathogenesis of experimental periodontal disease and experimental arthritis.

OBJECTIVES: To investigate the suggested role of Porphyromonas gingivalis peptidylarginine deiminase (PAD) in the relationship between the aetiology of periodontal disease and experimentally induced arthritis and the possible association between these two conditions. METHODS: A genetically modified PAD-deficient strain of P. gingivalis W50 was produced. The effect of this strain, compared to the wild type, in an established murine model for experimental periodontitis and experimental arthritis was assessed. Experimental periodontitis was induced following oral inoculation with the PAD-deficient and wild type strains of P. gingivalis. Experimental arthritis was induced via the collagen antibody induction process and was monitored by assessment of paw swelling and micro-CT analysis of the radio-carpal joints. Experimental periodontitis was monitored by micro CT scans of the mandible and histological assessment of the periodontal tissues around the mandibular molars. Serum levels of anti-citrullinated protein antibodies (ACPA) and P. gingivalis were assessed by ELISA. RESULTS: The development of experimental periodontitis was significantly reduced in the presence of the PAD-deficient P. gingivalis strain. When experimental arthritis was induced in the presence of the PAD-deficient strain there was less paw swelling, less erosive bone damage to the joints and reduced serum ACPA levels when compared to the wild type P. gingivalis inoculated group. CONCLUSION: This study has demonstrated that a PAD-deficient strain of P. gingivalis was associated with significantly reduced periodontal inflammation. In addition the extent of experimental arthritis was significantly reduced in animals exposed to prior induction of periodontal disease through oral inoculation of the PAD-deficient strain versus the wild type. This adds further evidence to the potential role for P. gingivalis and its PAD in the pathogenesis of periodontitis and exacerbation of arthritis. Further studies are now needed to elucidate the mechanisms which drive these processes.

Human cadaveric histomorphological and metallurgical analysis of dental implants following 12.5 years of service.

OBJECTIVES: To provide a metallurgical and histomorphological analysis of hybrid bridgework and associated dental implants which have been in a clinical load bearing situation for a period of 12.5 years. MATERIAL AND METHODS: The physical integrity of the hybrid framework was examined with stereoimaging microscopy and scanning electron microscopy for signs of wear, fatigue cracks, corrosion. Elemental spectra and maps of the surface were analysed with an EDAX Detecting Unit (AMETEK, Inc, Mahwah, NJ, USA). Similarly, the supporting titanium abutments screwed into the implants were examined for fatigue and corrosion. Bone density scans and bone trabecular patterns were obtained from radiographs. Microcomputer tomography was used to assess the bone-implant interface and bone architecture around the implants. Histological sections were stained with 1% basic fuchsin to assess osseous microdamage. RESULTS: The study demonstrated that the gold alloy framework to be in satisfactory condition with little indication of corrosion or cracking. The interface between the gold alloy and the titanium abutments likewise demonstrated no obvious corrosion cells. No radiographic evidence of any adverse loss of bone around the implants was noted. Bone mineral density was related to implant position, being higher between the implants. Scanning electron micrograph images confirmed the good bone integration with the implant threads with a high level of organisation, maturation and adaptation for the entire length of the implant. There was no evidence of any microdamage. CONCLUSIONS: The implants, abutments and hybrid framework were in remarkably good condition considering their length of service.

Periodontal-ligament-derived stem cells exhibit the capacity for long-term survival, self-renewal, and regeneration of multiple tissue types in vivo.

Primary periodontal ligament stem cells (PDLSCs) are known to possess multidifferentiation potential and exhibit an immunophenotype similar to that described for bone-marrow-derived mesenchymal stem cells. In the present study, bromo-deoxyuridine (BrdU)-labeled ovine PDLSCs implanted into immunodeficient mice survived after 8 weeks post-transplantation and exhibited the capacity to form bone/cementum-like mineralized tissue, ligament structures similar to Sharpey's fibers with an associated vasculature. To evaluate self-renewal potential, PDLSCs were recovered from harvested primary transplants 8 weeks post-transplantation that exhibit an immunophenotype and multipotential capacity comparable to primary PDLSCs. The re-derived PDLSCs isolated from primary transplants were implanted into secondary ectopic xenogeneic transplants. Histomorphological analysis demonstrated that four out of six donor re-derived PDLSC populations displayed a capacity to survive and form fibrous ligament structures and mineralized tissues associated with vasculature in vivo, although at diminished levels in comparison to primary PDLSCs. Further, the capacity for long-term survival and the potential role of PDLSCs in dental tissue regeneration were determined using an ovine preclinical periodontal defect model. Autologous ex vivo-expanded PDLSCs that were prelabeled with BrdU were seeded onto Gelfoam(®) scaffolds and then transplanted into fenestration defects surgically created in the periodontium of the second premolars. Histological assessment at 8 weeks post-implantation revealed surviving BrdU-positive PDLSCs associated with regenerated periodontium-related tissues, including cementum and bone-like structures. This is the first report to demonstrate the self-renewal capacity of PDLSCs using serial xenogeneic transplants and provides evidence of the long-term survival and tissue contribution of autologous PDLSCs in a preclinical periodontal defect model.

Regeneration of periodontal tissues using allogeneic periodontal ligament stem cells in an ovine model.

AIM: To investigate the capacity of allogeneic periodontal ligament stem cells (PDLSCs) to regenerate periodontal tissues using an ovine periodontal defect model. MATERIALS & METHODS: Surgically created zero-wall dehiscence periodontal defects created in Merino sheep were filled with 1 × 10(7) allogeneic PDLSCs attached to Gelfoam(®), Gelfoam alone or left untreated. After 4 weeks, histological analysis was performed to assess periodontal regeneration. RESULTS: Allogeneic PDLSCs were well tolerated by recipient animals. The mean area of new alveolar bone was significantly greater in the PDLSC + Gelfoam treatment group compared with the defect-alone group. The PDLSC + Gelfoam and Gelfoam-only treatment groups displayed significantly greater length of new cementum and percentage of cementum regrowth compared with the defect-alone group. New Sharpey's fibers were generally more organized and significantly thicker within the PDLSC + Gelfoam treatment group. The PDLSC + Gelfoam treatment group also showed a trend of increased Sharpey's fiber attachment length compared with the Gelfoam-only and defect-alone groups. CONCLUSION: These studies support the potential use of allogeneic PDLSC preparations as viable therapies for periodontal regeneration in the clinical setting.

Effect of PDGF-BB and beta-tricalcium phosphate (ß-TCP) on bone formation around dental implants: a pilot study in sheep.

OBJECTIVES: The aim of this investigation was to examine the effect of a combination of purified recombinant human platelet-derived growth factor (rhPDGF-BB) mixed with a synthetic beta-tricalcium phosphate (ß-TCP) on bone healing around dental implants with critical size circumferential defects. MATERIAL AND METHODS: Three critical size circumferential defects were prepared in the ilium of six sheep. Three dental implants were placed into the centre of each defect and the 3.25 mm circumferential gap was filled with (a) blood clot alone; (b) ß-TCP; (c) rhPDGF-BB (0.3 mg/ml) with ß-TCP. All the defects in each group were covered with a Bio-Gide(®) resorbable barrier membrane. The sheep were sacrificed at 2 and 4 weeks and histological and histomorphometric analyses were performed to determine the percentage of new mineralized bone formation and residual ß-TCP graft particles in the defects. RESULTS: Defects filled with rhPDGF-BB/ß-TCP showed the highest rate of bone formation after 2 and 4 weeks with limited degradation of the ß-TCP particles over 4 weeks. Defects filled with ß-TCP showed the least bone fill after 2 and 4 weeks, and faster degradation of the ß-TCP particles over 4 weeks compared with defects filled with rhPDGF-BB/ß-TCP. Percentage of new mineralized bone was comparable in defects to blood clot alone and ß-TCP after 4 weeks of healing, but there was a collapse in the defect area in defects with blood clot alone. In comparison, the space was maintained when ß-TCP was used in defects at 4 weeks. CONCLUSIONS: Defects which had ß-TCP alone showed an inhibition in bone healing at 2 and 4 weeks; however, the combination of rhPDGF-BB with ß-TCP enhanced bone regeneration in these peri-implant bone defects at the same time intervals.

Soft tissue attachment to titanium implants coated with growth factors.

BACKGROUND: Enhancing the connective tissue seal around dental implants may be an important factor in implant survival. PURPOSE: The objective of the study was to investigate the effect of implant surface modification with either platelet-derived growth factor (PDGF) or enamel matrix derivative (EMD) on connective tissue attachment to titanium implants. MATERIALS AND METHODS: Eighteen implants (Branemark® Mk III Groovy NP (3.3 mmØ × 10 mm, Nobel Biocare) were implanted subcutaneously into 12 rats. Six implants each were coated with either PDGF or EMD immediately prior to implantation and six implants were left uncoated. Implants were retrieved at 4 and 8 weeks and assessed histologically to compare the soft tissue adaptation to the implant surfaces. RESULTS: Ingrowth by soft connective tissue into the threads of all implants was noted at 4 and 8 weeks. Coating with growth factors did not alter the orientation of fibroblasts and collagen fibers. The depth of connective tissue penetration into the implant grooves was significantly greater for the implants coated with PDGF at 4 weeks. The thickness of the connective tissue in growth was significantly less for the implants coated with PDGF at 8 weeks. CONCLUSION: Coating of the implant surface with rhPDGF-BB or EMD can increase the speed and quantity of soft tissue healing around the implant surface.

Effect of coating Straumann Bone Ceramic with Emdogain on mesenchymal stromal cell hard tissue formation.

Periodontal tissue engineering requires a suitable biocompatible scaffold, cells with regenerative capacity, and instructional molecules. In this study, we investigated the capacity of Straumann Bone Ceramic coated with Straumann Emdogain, a clinical preparation of enamel matrix protein (EMP), to aid in hard tissue formation by post-natal mesenchymal stromal cells (MSCs) including bone marrow stromal cells (BMSCs) and periodontal ligament fibroblasts (PDLFs). MSCs were isolated and ex vivo-expanded from human bone marrow and periodontal ligament and, in culture, allowed to attach to Bone Ceramic in the presence or absence of Emdogain. Gene expression of bone-related proteins was investigated by real time RT-PCR for 72 h, and ectopic bone formation was assessed histologically in subcutaneous implants of Bone Ceramic containing MSCs with or without Emdogain in NOD/SCID mice. Alkaline phosphatase activity was also assessed in vitro, in the presence or absence of Emdogain. Collagen-I mRNA was up-regulated in both MSC populations over the 72-h time course with Emdogain. Expression of BMP-2 and the osteogenic transcription factor Cbfa-1 showed early stimulation in both MSC types after 24 h. In contrast, expression of BMP-4 was consistently down-regulated in both MSC types with Emdogain. Up-regulation of osteopontin and periostin mRNA was restricted to BMSCs, while higher levels of bone sialoprotein-II were observed in PDLFs with Emdogain. Furthermore, alkaline phosphatase activity levels were reduced in both BMSCs and PDLFs in the presence of Emdogain. Very little evidence was found for ectopic bone formation following subcutaneous implantation of MSCs with Emdogain-coated or -uncoated Bone Ceramic in NOD/SCID mice. The early up-regulation of several important bone-related genes suggests that Emdogain may have a significant stimulatory effect in the commitment of mesenchymal cells to osteogenic differentiation in vitro. While Emdogain inhibited AP activity and appeared not to induce ectopic bone formation, longer-term studies are required to determine whether it promotes the final stages of osteoblast formation and mineralization at gene and protein levels. While used in clinical applications, whether Emdogain and other commercial preparations of EMPs truly possess the capacity to induce the regeneration of bone or other components of the periodontium remains to be established.

Pre-existing periodontitis exacerbates experimental arthritis in a mouse model.

AIMS: Previous studies have shown a higher incidence of alveolar bone loss in patients with rheumatoid arthritis (RA) and that patients with periodontitis are at a greater risk of developing RA. The aim of this study was to develop an animal model to assess the relationship between pre-existing periodontitis and experimental arthritis (EA). METHODS: Periodontitis was first induced in mice by oral gavage with Porphyromonas gingivalis followed by EA using the collagen antibody-induced arthritis model. These animals were compared with animals with periodontitis alone, EA alone and no disease (controls). Visual changes in paw swelling were assessed to determine clinical development of EA. Alveolar bone and joint changes were assessed using micro-CT, histological analyses and immunohistochemistry. Serum levels of C-reactive protein were used to monitor systemic inflammation. RESULTS: Mice with pre-existing periodontitis developed more severe arthritis, which developed at a faster rate. Mice with periodontitis only also showed evidence of loss of bone within the radiocarpal joint. There was also evidence of alveolar bone loss in mice with EA alone. CONCLUSIONS: The results of this study indicate that pre-existing periodontitis exacerbated experimental arthritis in a mouse model.

Pharmacological actions of oximino-propofol analogues at GABA(B) autoreceptors.

1. GABA(B) autoreceptors are a subclass of GABA(B) receptors that inhibit the release of [(3) H]GABA from GABAergic nerve terminals. Baclofen is an agonist that reduces [(3)H]GABA, whilst the antagonist (+)-(S)-5,5-dimethylmorpholinyl-2-acetic acid (Sch 50911) enhances [(3)H]GABA release in electrically-stimulated rat neocortical brain slices preloaded with [(3)H]GABA. Here, the pharmacological actions of a series of compounds derived from the positive allosteric modulator, 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930), were examined on GABA(B) autoreceptors. 2. The compound, 3-(3,5-ditbutyl-4-hydroxyphenyl)-2,2-dimethyl-1-oximinopropane (compound 2), at 10 µmol/L had little effect on the stimulation-induced overflow of [(3)H]GABA when superfused alone, but when superfused in the presence of baclofen (2 µmol/L) inhibited the overflow of [(3)H]GABA. These effects were reversed by Sch 50911 (10 µmol/L). Although compounds 1-(4-chlorophenyl)-3-(4-hydroxy-3,5-diisopropylphenyl)-2-methyl-1-oximinopropane (compound 1), 1-[(3,5-ditbutyl-4-hydroxyphenyl)methyl]-1-oximinomethylcyclohexane (compound 3), 3-(3,5-ditbutyl-4-hydroxyphenyl)-1,2-diphenyl-1-oximinopropane (compound 4) and 4-(3,5-ditbutyl-4-hydroxyphenyl)-3-methyl-2-oximinobutane (compound 5) (each at 10 µmol/L) tended to reduce the stimulation-induced overflow in the presence of baclofen, an effect reversed by Sch 50911, their status as modulators is not confirmed in the present study. 3. Another derivative, 3-(3,5-ditbutyl-4-hydroxyphenyl)-1-(4-chlorophenyl)-2-methyl-1-oximinopropane (compound 6) (10 µmol/L), acted as an agonist as it inhibited the release of [(3)H]GABA by 32% (EC(50) of 3.3 µmol/L), an effect reversed by Sch 50911 (10 µmol/L). The other compounds, 1-[(3,5-ditbutyl-4-hydroxyphenyl)methyl]-1-methyl-2-oximinocyclohexane (compound 7), 4-(3,5-ditbutyl-4-hydroxyphenyl)-3,3-dimethyl-2-oximinobutane (compound 8) and 4-(4-hydroxy-3,5-diisopropylphenyl)-3,3-dimethyl-2-oximinobutane (compound 9) (each at 10 µmol/L), were inactive. 4. These findings indicate that this series of compounds show different modes of activity at GABA(B) autoreceptors.