Maxillary Sinus Of Rabbits Research Articles

Sustained co-release of ciprofloxacin and dexamethasone in rabbit maxillary sinus using polyvinyl alcohol-based hydrogel microparticle

Topical delivery to paranasal sinuses through sustained-release stents is one of the new horizons in treating chronic rhinosinusitis (CRS). This study aims to introduce and evaluate sustained co-release of encapsulated ciprofloxacin (CIP) and dexamethasone (DEX) in polyvinyl alcohol-based carriers within the maxillary sinus of rabbit animals. DEX and CIP were loaded in a tyramine-substituted polyvinyl alcohol microparticle (PVATyr MP). The mechanical stability, degradability, and sustained-release patterns of both drugs as well as cellular cytocompatibility were assessed in vitro. The PVATyr MPs were then injected into the maxillary sinus of rabbits and they were monitored weekly for 21 days. Nasal endoscopy, MRI imaging, and tissue microscopy were used to follow the changes and compared them with the control condition. Also, the concentrations of drugs were evaluated in the maxillary sinus and blood samples over the study period. Produced PVA-based MPs possessed a relatively narrow particle size distribution (CV 7.7%) with proper physical stability until 30 days of incubation. The uniform-sized PVATyr MPs and their surrounding hydrogel showed sustained-release profiles for DEX and CIP for up to 32 days in vitro. The injected drugs-loaded hydrogel showed complete clearance from the maxillary sinus of rabbits within 28 days. The concentrations of DEX and CIP in mucosal remained within the therapeutic window when measured on days 7, 14, and 21, which were well above the plasma concentrations without any pathological changes in endoscopy, MRI imaging, and histological examinations. DEX/CIP loaded PVATyr MPs provided an effective, controlled, and safe sustained-drug delivery in both in vitro and in vivo analyses at therapeutic concentrations with minimal systemic absorption, suggesting a promising treatment approach for CRS.Graphical

Glutathione and bicarbonate nanoparticles improve mucociliary transport in cystic fibrosis epithelia.

Cystic fibrosis (CF) airway disease is characterized by thick mucus and impaired mucociliary transport (MCT). Loss of functional cystic fibrosis transmembrane receptor (CFTR) leads to acidification and oxidation of airway surface mucus. Replacing bicarbonate (HCO3 -) topically fails due to rapid reabsorption and neutralization, while the scavenging antioxidant, glutathione sulfhydryl (GSH), is also rapidly degraded. The objective of this study is to investigate GSH/NaHCO3 nanoparticles as novel strategy for CF airway disease. GSH/NaHCO3 poly (lactic-co-glycolic acid) nanoparticles were tested on primary CF (F508del/F508del) epithelial cultures to evaluate dose-release curves, surface pH, toxicity, and MCT indices using micro-optical coherence tomography. In vivo tests were performed in three rabbits to assess safety and toxicity. After 1week of daily injections, histopathology, computed tomography (CT), and blood chemistries were performed and compared to three controls. Fluorescent nanoparticles were injected into a rabbit with maxillary sinusitis and explants visualized with confocal microscopy. Sustained release of GSH and HCO3 - with no cellular toxicity was observed over 2weeks. Apical surface pH gradually increased from 6.54±0.13 (baseline) to 7.07±0.10 (24h) (p<0.001) and 6.87 ± 0.05 at 14 days (p<0.001). MCT, ciliary beat frequency, and periciliary liquid were significantly increased. When injected into the maxillary sinuses of rabbits, there were no changes to histology, CT, or blood chemistries. Nanoparticles penetrated rabbit sinusitis mucus on confocal microscopy. Findings suggest that GSH/NaHCO3 - nanoparticles are a promising treatment option for viscous mucus in CF and other respiratory diseases of mucus obstruction such as chronic rhinosinusitis.

Study on osteogenesis and angiogenesis of Pluronic F-127 composite gel loaded with transforming growth factor β 3 and bone marrow mesenchymal stem cells in rabbit maxillary sinus lift

To prepare Pluronic F-127 composite gel loaded with transforming growth factor β 3 (TGF-β 3) and bone marrow mesenchymal stem cells (BMSCs) and observe its osteogenesis and angiogenesis effects in vivo and in vitro. BMSCs were isolated from the tibial and femoral bone marrow of New Zealand white rabbits and passaged, and the 3rd generation cells were used for subsequent experiments after identification of osteogenic and adipogenic induction. Pluronic F-127 powder and TGF-β 3 were dissolved in L-DMEM medium to prepare Pluronic F-127 gel, TGF-β 3+Pluronic F-127 gel, BMSCs+Pluronic F-127 gel, and TGF-β 3+BMSCs+Pluronic F-127 gel. The 3rd generation of BMSCs were cultured with L-DMEM medium (group A), osteogenic induction medium (group B), osteogenic induction medium containing Pluronic F-127 gel (group C), and osteogenic induction medium containing TGF-β 3+Pluronic F-127 gel (group D), respectively. After 14 days of culturing, alkaline phosphatase (ALP) staining and Alizarin red staining were used to observe the osteogenesis. In addition, the BMSCs were cultured with L-DMEM medium containing Pluronic F-127 gel (experimental group) and L-DMEM medium (control group) for 1, 2, 3, and 4 days, respectively. And the cell proliferation was detected by MTT assay. Ten New Zealand white rabbits were taken to prepare the maxillary sinus lift models, and Pluronic F-127 gel (group A), TGF-β 3+Pluronic F-127 gel (group B), BMSCs+Pluronic F-127 gel (group C), and TGF-β 3+BMSCs+Pluronic F-127 gel (group D) were injected into the bone defects, respectively. On the 8th week, imaging examination and HE staining were used to observe the formation of new bone, immunohistochemical staining was used to observe the expression of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2) in bone tissue, and Western blot was used to detect the relative expressions of VEGF, oncostatin M (OSM), and BMP-4 proteins in bone tissue. Osteogenic and adipogenic induction identified the isolated and cultured cells as BMSCs. In vitro staining showed that ALP activity and Alizarin red concentration in group D were significantly higher than those in other groups ( P<0.05). MTT assay showed that the absorbency ( A) value of the two groups increased gradually, and there was no significant difference between the groups at each time point ( P>0.05). In vivo experimental imaging examination showed that the bone mineral density and osteogenic continuity of group D were the best, and the proportion of new bone volume was superior to other groups ( P<0.05). HE staining showed that compared with other groups, bone trabeculae in group D were dense and arranged regularly, on which a large number of osteoblasts and osteoclasts were distributed, and a large number of new bone formation could be seen. Immunohistochemical staining showed the strong positive expressions of BMP-2 and VEGF in group D ( P<0.05); Western blot detection showed that the relative expressions of VEGF, OSM, and BMP-4 proteins in group D were significantly higher than those in other groups ( P<0.05). The BMSCs in Pluronic F-127 composite gel loaded with TGF-β 3 and BMSCs can be induced to differentiate into osteoblasts, and the composite gel has no toxic effect on cells, and has obvious osteogenesis and angiogenesis in the maxillary sinus of rabbits.

COMPARATIVE STUDY BETWEEN THE USE OF AMNIOTIC MEMBRANE AND FIBRIN GLUE FOR THE REPAIR OF PERFORATED MAXILLARY SINUS (AN EXPERIMENTAL STUDY)

Introduction: Maxillary sinus membrane perforation is the most common intraoperative complications associated with the sinus lifting procedure. There are various sutureless techniques used in repairing of perforated sinus membrane including; collagen membrane, fibrin sealants, cyanoacrylate adhesives,amniotic membrane and fibringlue. Objectives: The aim of this study was to compare between the use of amniotic membrane and fibrin glue in healing of perforated maxillary sinus in rabbits. MATERIALS AND METHOD: This study was conducted on ten adult healthy male rabbits, with an average weight between 2-3 kgs. A split mouth design was implemented. In each rabbit, the right sinus membrane window was repaired by fibrin glue (group I), while the left sinus membrane window was repaired by amniotic membrane (group II). Results: Histological results revealed that amniotic membrane enhanced faster reepithelialization of maxillary sinus membrane and bone healing where the amount of the newly formed bone observed in group II was greater than that of group I. Histomorphometric analysis showed the increase in the bone surface area mean percentage in group II in comparison to group I. Conclusion: According to the results of the present study, it was concluded that the amniotic membrane is effective in the repair of perforated sinus membrane with superior potentiality than fibrin glue especially in the early stage.

Distinct healing pattern of maxillary sinus augmentation using the vitroceramic Biosilicate®: Study in rabbits

ObjectivesTo follow healing process of augmented maxillary sinus in rabbits analyzing the histological pattern of bone tissue formation, along with the osteogenic activity and vascularization using a bioactive vitroceramic in comparison to deproteinized bovine bone associated or not with autogenous bone graft. DesignForty five male adult New Zealand rabbits, 5 months of age, mean weight of 4 Kg, underwent bilateral sinus augmentation surgeries to be divided in five groups: G – (Control) particulate autogenous bone graft (AG), BO - deproteinized bovine bone, BO+G - deproteinized bovine bone + AG, BSi –vitroceramic, and BSi + G – vitroceramic +AG. After 15, 45 and 90 days, all animals were euthanized for specimen's removal to be analyzed under light microscopy, histomorphometry, and immunohistochemistry for Runx2 and VEGF labeling. ResultsG, BO and BO+G groups healed uneventfully, allowing the formation of mature remodeling bone at day 90, regarding the association of AG with the biomaterial. On the other hand, BSi and BSi + G groups showed an important cellular reaction and granulation/fibrous tissue formation from the first to the last period of observation. Runx-2 and VEGF immunolabeling were coherent with this result. However, histomorphometry did not reveal significant differences considering new bone formation. ConclusionsReconstructed maxillary sinuses using Biosilicate® permitted satisfactory new bone formation in comparison to the deproteinized bovine bone and AG. However, the presence of granulation/fibrous tissue and inflammatory cells associated to the degrading biomaterial indicate that further studies should be careful performed considering the immunological aspect of this new biomaterial.

Sinus augmentation using rhBMP-2-loaded synthetic bone substitute with simultaneous implant placement in rabbits.

PurposeThe aim of this study was to determine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded synthetic bone substitute on implants that were simultaneously placed with sinus augmentation in rabbits.MethodsIn this study, a circular access window was prepared in the maxillary sinus of rabbits (n=5) for a bone graft around an implant (Ø 3×6 mm) that was simultaneously placed anterior to the window. Synthetic bone substitute loaded with rhBMP-2 was placed on one side of the sinus to form the experimental group, and saline-soaked synthetic bone substitute was placed on the other side of the sinus to form the control group. After 4 weeks, sections were obtained for analysis by micro-computed tomography and histology.ResultsVolumetric analysis showed that the median amount of newly formed bone was significantly greater in the BMP group than in the control group (51.6 mm3 and 46.6 mm3, respectively; P=0.019). In the histometric analysis, the osseointegration height was also significantly greater in the BMP group at the medial surface of the implant (5.2 mm and 4.3 mm, respectively; P=0.037).ConclusionsIn conclusion, an implant simultaneously placed with sinus augmentation using rhBMP-2-loaded synthetic bone substitute can be successfully osseointegrated, even when only a limited bone height is available during the early stage of healing.

The staphylococcal enterotoxin burden determines the ultrastructure of ciliated epithelia and inflammatory changes in maxillary sinus mucosa of rabbits

To investigate the ultrastructure of ciliated epithelia and inflammatory changes upon repeated exposure to staphylococcal enterotoxin A (SEA) of different concentrations in the maxillary sinus mucosa of rabbits. The rabbits were randomly divided into 2 groups (24 rabbits per group): low-dose SEA group and high-dose SEA group. The low-dose SEA group and high-dose SEA group received daily injections of 0.6 ng of SEA (2 ml) and 60 ng of SEA (2 ml) into the left maxillary sinus of rabbits for 28 days, respectively. Concurrent treatment of the right maxillary sinus with normal saline was used as control. Six rabbits chosen randomly in two groups were examined by computed tomography (CT) scans and then sacrificed to obtain the sinus mucosa from the two-side of maxillary sinuses for histological assessment on days 3, 7, 14 and 28. To characterize the inflammatory changes of the sinus mucosa examined using light microscope, hematoxylin and eosin (HE) and toluidine blue staining was performed. Scanning and transmission electron microscopy were performed to observe ultrastructure of ciliated epithelia in the maxillary sinus mucosa. SPSS 13.0 software was used to analyze the data. On days 14 and 28, CT images showed opacification of the left maxillary sinus in the high-dose SEA group. The percentage of epithelial disruption was (22.73 ± 5.72) % and (30.79 ± 4.30)% in the high-dose SEA group respectively, and were significantly greater than those in the low-dose SEA group (5.12% ± 1.98% and 5.38% ± 1.64%, q value was 10.079 and 19.132) and control group (4.08% ± 1.29% and 4.81% ± 1.62%, q value was 11.016 and 19.592, respectively, all P < 0.01). The subepithelial thickness in the high-dose SEA group was (113.34 ± 14.81)µm and (120.86 ± 12.35) µm respectively, and were significantly different from those of the low-dose SEA group [(71.08 ± 10.39)µm and (81.63 ± 9.32)µm, q value was 8.090 and 8.782] and control group [(37.45 ± 7.67)µm and (38.79 ± 7.68)µm, q value was 15.759 and 19.541, all P < 0.01]. Viewed under the electron microscope, loss of cilia was observed, a few compound cilia and cytoplasmic protrusion were found, an obvious stretching of the endoplasmic reticulum and an obvious turgescence of the mitochondria was also observed. However, in the low-dose SEA group on days 14 and 28, CT scan of the left maxillary sinus showed transparency; light microscopy observations of the maxillary sinus mucosa showed the number of eosinophils was markedly increased as compared with the high-dose SEA and control groups, the differences were significant (q value was 5.871 and 6.766 on day 14, and q value was 7.572 and 8.970 on day 28, respectively, all P < 0.05). But no significant differences were observed in epithelial disruption between the low-dose SEA and the control groups on days 14 and 28 (q value was 1.512 and 0.859 respectively, all P > 0.05); inordinate array and adhesion of cilia was observed, but cilia loss, compound cilia, cytoplasmic protrusions, mitochondrial swelling and endoplasmic reticulum stretching were not found. SEA may induce allergic inflammation of the sinus mucosa without damaging the structure of ciliated epithelia at low concentration. Whereas SEA impairs the structure of mitochondria and endoplasmic reticulum in ciliated epithelial cells at high concentration, and results in cilia loss and epithelial disruption, which may be one of the main reasons to induce acute sinusitis.

Low-Dose Recombinant Human Bone Morphogenetic Protein-2 to Enhance the Osteogenic Potential of the Schneiderian Membrane in the Early Healing Phase: In Vitro and In Vivo Studies

The objectives of this study were to confirm the osteogenic potential of the Schneiderian membrane and to elucidate the early healing pattern of low-dose recombinant human bone morphogenetic protein-2 (rhBMP-2)-coated biphasic calcium phosphate (BCP). The osteogenic potential of the Schneiderian membrane and enhancement by rhBMP-2 were evaluated by in vitro analysis. RhBMP-2-coated BCP (experimental group) and BCP soaked with saline (control group) were applied to the maxillary sinus in rabbits. After 2 weeks, micro-computed tomographic and histometric analyses were performed. Enhanced osteogenic potential was found when cells from the Schneiderian membrane were treated with rhBMP-2. Micro-computed tomographic analysis showed that the total augmented volume was significantly larger in the experimental group. Different healing patterns were observed in 3 regions, although the area of new bone did not differ significantly. Although more newly formed bone appeared, particularly along the Schneiderian membrane in the experimental group, the difference was not statistically significant. RhBMP-2 enhanced the osteogenic potential of the Schneiderian membrane in vitro. However, low-dose rhBMP-2-coated BCP failed to exert a statistically significant effect in vivo, although it appeared to be effective in sinus augmentation specifically for the volumetric increase in the early phase.

A Simple Animal Model of Staphylococcus Aureus Biofilm in Sinusitis

Previous research suggested that the biofilm of Staphylococcus aureus contributes greatly to the recalcitrant nature of chronic rhinosinusitis (CRS). However, the lack of a simple and stable animal model limited further study in this field. The aim of this study was to create a convenient animal model of S. aureus biofilms in the maxillary sinus of rabbit. New Zealand white rabbits were used as model animals and incised vertically along the median line of the nasal dorsum to expose the anterolateral wall of maxillary sinus, on which a 1.5-mm-diameter hole was drilled to enter the sinus cavity. Through the hole, a piece of gelatin sponge was inserted and then inoculated bacterial suspension into the maxillary sinus. One to 8 weeks after the surgery, the sinus mucosa were harvested and examined with scanning electron microscopy (SEM) and hematoxylin and eosin (H&E) staining. All rabbits tolerated the surgical procedures and had developed sinusitis by the time they were killed. SEM revealed that biofilms were presented in 100% of rabbits who had bacteria infected for ≥2 weeks, during which the ciliated epithelial cells were encapsulated and gradually destroyed. H&E staining revealed morphological changes of the epithelial cells and infiltration of inflammatory cells in the subepithelial layer, which showed a strong correlation with the results of SEM. This biofilm model of sinusitis avoids excessive damage to the nasal cavity and sinuses of the rabbits. It may be a desirable animal model for studying the pathogenesis and eradication strategies of bacterial biofilms in sinusitis.

Comparative study of two autogenous graft techniques using piezosurgery for sinus lifting

Maxillary sinus lifting is a technique, in which, a possible complication is sinus membrane perforation. The aim of this study was to compare two techniques using ultrasound surgery to perform autogenous graft for maxillary sinus lifting. Ten rabbits were used in the study, one of them did not undergo surgery. The other nine rabbits had their maxillary sinuses filled with autogenous bone grafts collected from the external skull diploe in particulate form on the right side, and shaved on the left side, both with ultrasonic device. Data on bone density in left and right maxillary sinus, obtained by computed tomography in transverse and longitudinal sections, recorded 90 days after the grafts, were statistically compared. There were no statistically significant differences between the two techniques that used shaved and particulate bone collected by means of ultrasonic device from rabbit skulls. Assessment of operative procedures led to the conclusion that piezoelectric ultrasound was shown to be a safe tool in the surgical approach to the maxillary sinus of rabbits, allowing sinus membrane integrity to be maintained during surgical procedures.

Retinoic Acid Improves Ciliogenesis after Surgery of the Maxillary Sinus in Rabbits

Retinoids have been shown to be important cofactors in regulating the differentiation and proliferation of ciliated epithelial cells of the respiratory tract. In particular, retinoic acid has been shown to enhance the regeneration of paranasal sinus mucosa. The objective of this study is to use scanning electron microscopy techniques to evaluate the effect of topical retinoic acid on mucosal wound healing in a rabbit model of maxillary sinus surgery. It is hypothesized that the application of topical retinoic acid will enhance ciliogenesis and improve the morphology of regenerated cilia compared with controls. Prospective multi-arm controlled animal trial. Eighteen New Zealand white rabbits underwent surgical opening of the maxillary sinuses through a midline incision. The rabbits were divided among four experimental groups: 1) mucosal stripping alone (stripped control), 2) stripping followed by topical application of an inert aqueous gel, 3) stripping followed by application of 0.01% retinoic acid in aqueous gel, and 4) no mucosal stripping and no topical treatment (nonstripped control). After 14 days, the medial wall of the maxillary sinus was harvested and examined by scanning electron microscopy at x2,000 and x5,000 magnification. The micrographs were then rated by a blinded review panel for ciliary density, orientation, and morphology. Mean scores for ciliary density, orientation, and morphology were all significantly higher for the retinoic acid treatment group compared with both the inert aqueous gel treatment group and the stripped control group (P=.004-.03 for all comparisons, Student's t test). Mean scores for the retinoic acid treatment group were numerically lower than the nonstripped control group but did not approach statistical significance for any parameter (P=.23-.31). In a rabbit model of maxillary sinus surgery, topically delivered retinoic acid enhances ciliogenesis. Qualitative assessment of ciliary density, orientation, and morphology shows improved healing in retinoic acid treated sinuses compared with both untreated control sinuses and aqueous gel treated sinuses.

Early Effect of Exogenous Na Hyaluronate on Mucociliary Clearance

An animal study is performed to determine the early effect of 1% Na hyaluronate on mucociliary clearance function. One percent of Na hyaluronate was introduced into the maxillary sinuses of rabbits by anterior antrostomy. A physiological solution of 1% NaCl was introduced into the maxillary sinuses of a control group to equalize the influence of Na for both groups. The treatment material was sprayed with an atomizer for coating the maxillary sinus lining. Technetium-99m diethylenetriamine pentaacetate dynamic scintigraphic imaging was performed to evaluate mucociliary clearance function on all rabbits 72 hours after the surgical procedure. Although the mean rate of mucociliary clearance of the Na hyaluronate group was slightly worse than the control group; there was no statistically significant difference between them. There is no early effect of exogenous 1% Na hyaluronate on mucociliary clearance function.

Histomorphometric study of the stability of newly formed bone after elevation of the floor of the maxillary sinus

We studied the remodelling process of newly formed bone and the distribution of osteoclasts in the augmented space after elevation of the floor of the maxillary sinus in rabbits. Histologically, 10 weeks after grafting, there was some newly formed lamellar bone embedded in fatty tissue. Histomorphometric analysis showed that the augmented height and augmented area decreased significantly from 2 to 6 weeks. The number of osteoclasts on newly formed bone, adjacent to the elevated sinus membrane, was significantly greater than in the augmented space at 2 and 4 weeks. We conclude that newly formed bone in the augmented space after grafting with blood clot is unstable during the early stage of bony regeneration.

Long-term outcome of augmentation of the maxillary sinus using deproteinised bone particles experimental study in rabbits

We studied the long-term outcome of deproteinised bone particles for augmentation of the maxillary sinus in rabbits. Histologically, 64 weeks after implantation, most of the newly formed bone in the augmented spaces had been absorbed. Histomorphometric analysis showed a significant reduction in the area of bone and a significant increase in the area of bone marrow. There was no substantial change in the area of deproteinised bone particles. We conclude that deproteinised bone particles do not absorb with time and that the newly formed bone in the augmented space after implantation is not stable in the long-term.

Effect of WEB 2170 BS, platelet activating factor receptor inhibitor, in the rabbit model of sinusitis.

Platelet activating factor (PAF), a potent inflammatory mediator, is a biologically active phospholipid. Recent studies have shown that PAF may play an important role in the pathogenesis of inflammation. WEB 2170 BS has been shown to be a PAF antagonist both in vitro and in vivo. Nitric oxide (NO) is present in the mammalian nasal airways and originates primarily from the paranasal sinuses. Measurement of NO is thought to be a surrogate marker of upper airway inflammation. In this study, the antiinflammatory effects of WEB 2170 BS were investigated in a rabbit model of sinusitis. To induce experimental sinusitis, we applied killed Staphylococcus aureus percutaneously to the maxillary sinus of rabbits without occlusion of the natural ostium. Either WEB 2170 BS solution or placebo was administered intraperitoneally 2 hours before sinus inoculation, and this procedure was repeated twice daily for 4 days. The outcome of the treatment was determined by the measurement of NO metabolite levels and NO synthase activity in the samples of sinus mucosa and by histopathologic evaluation of sinus mucosa. The pathological grading was determined by the number of inflammatory cells found in the sinus mucosa. The levels of NO metabolites and NO synthase activity were found to be significantly lower in the WEB 2170 BS-treated group than in the control group. Histopathologic analysis of the sinus mucosa indicated decreased inflammation in the treated group as compared to the controls. These results demonstrate that WEB 2170 BS may produce significant anti-inflammatory effects in this model of sinusitis.

Effects of beta-toxin of Staphylococcus aureus on ciliary activity of nasal epithelial cells.

To investigate the in vitro effects of staphylococcal beta-toxin on ciliary activity and the in vivo effects on sinusitis induction. The in vitro effects of staphylococcal beta-toxin on ciliary activity were investigated at different concentrations and exposure times. Experimental sinusitis was induced in rabbits with application of beta-toxin and confirmed 7 days later. Ciliated epithelial cells were taken from the maxillary sinus mucosa of 10 rabbits. Five culture dishes from each rabbit were used for the experimental group, and one culture dish from each rabbit was used for the control group. In the experimental group, ciliary beat frequency (CBF) was measured at concentrations of 0.1, 1, 2, 5 and 10 U/mL of beta-toxin using a video-computerized analysis technique, while in the control group, culture medium containing no toxin was used. CBF was measured 1, 2, 4, 6, 8, 12, 24, and 48 hours after administration of beta-toxin. To induce experimental sinusitis, 2 U/mL of beta-toxin was percutaneously applied to the maxillary sinus of 10 rabbits without occlusion of the natural ostium, while normal saline was percutaneously applied to the right-side maxillary sinus of 4 rabbits in the control group. At 7 days, mucosal membranes were taken from the inferomedial wall of the maxillary sinus for light microscopic study. CBF dropped significantly after an 8-hour incubation at 2, 5, and 10 U/mL of beta-toxin. No ciliary activity was observed after a 24-hour incubation at 2 and 5 U/mL and a 12-hour incubation at 10 U/mL of beta-toxin. Mucoid, purulent discharge was observed in the maxillary sinuses of the beta-toxin-applied group. Prominent epithelial disruption and infiltration of inflammatory cells into the epithelium and lamina propria were observed in the beta-toxin-applied group. Staphylococcal beta-toxin may reduce ciliary activity and induce sinusitis without occlusion of the natural ostium of the maxillary sinus in rabbits This study provides another animal model of sinusitis for understanding the pathogenesis of sinusitis induced by bacterial exotoxins.

Ultrastructural changes in platelet activating factor-induced epithelial damage in rabbit maxillary sinus mucosa.

Platelet activating factor (PAF), a potent chemical mediator in inflammation and allergic reaction, has been thought to induce mucociliary inhibition and epithelial damage in the airway mucosa. However, several recent papers have reported that PAF may not readily damage the airway epithelium. The aim of this study was to elucidate the pathogenesis of PAF-induced epithelial damage in terms of ultrastructural changes. Sixteen micrograms of PAF (1 mL of 16 microg/mL) was administered into the maxillary sinuses of rabbits. The rabbits were divided into 2 groups according to time intervals, and the antral mucosa was taken 1 and 3 days after administration of PAF. The tissue was processed for routine transmission electron microscopy. No epithelial degeneration was observed other than platelet aggregation, red blood cell stasis, and swelling of the endothelial cells 1 day after administration of PAF. Migration of inflammatory cells into the perivascular connective tissue, infiltration of eosinophils into the subepithelial and intraepithelial spaces, and vacuolar degeneration of the epithelial cells with focal loss of cilia were seen 3 days after administration of PAF. In conclusion, PAF induced infiltration of eosinophils into the epithelium, and resulted in epithelial degeneration that varied according to the time interval. Our findings suggest that PAF may cause epithelial damage through a series of secondary events, probably due to cytotoxicity of eosinophils infiltrating the epithelium.

Healing of osseous maxillary sinus defects using guided tissue regeneration: An experimental study in rabbits

The healing capabilities of the maxillary sinus in rabbits with and without a collagen barrier membrane after bilateral critical size defects were investigated at 4 wk after surgery. One maxillary sinus had a collagen membrane barrier positioned over the surgical site, whereas the other maxillary sinus surgical site served as a control. A histological evaluation showed that the experimental (barrier) defect had more complete osseous healing when compared with the control (nonbarrier) maxillary sinus defect. From the analysis of the Student's <i>t</i> test for paired samples and the Wilcoxonpaired signed-ranks test, the healing capabilites of the maxillary sinus with the collagen barrier membrane could be considered statistically significant. It seems that the placement of the collagen barrier membrane after maxillary sinus exposure could have a beneficial effect.

Correlation of Middle Meatal and Maxillary Sinus Cultures in Acute Maxillary Sinusitis

Cultures obtained from the middle meatus have been used frequently in the past to direct therapy in patients with acute maxillary sinusitis. However, no convincing data have been published to indicate that middle meatal cultures accurately represent the bacterial flora within the maxillary sinus. The hypothesis of this experiment is that bacteria obtained by directed middle meatal cultures qualitatively and quantitatively correlate with cultures taken by maxillary sinus puncture. Acute sinusitis was induced by injecting 10(8) colony-forming units of bacteria directly into the maxillary sinuses of rabbits in which the ostia were occluded with cotton packs. Eight animals were injected with Staphylococcus aureus, eight with Haemophilus influenzae, and eight with Streptococcus pneumoniae. The packs were removed after 3 days, and specimens were obtained from the middle meatus in the region of the maxillary sinus ostium, and from the maxillary sinus, 1 day later. The contralateral maxillary sinuses of six of the animals were injected with normal saline and served as controls. There was a 100% correlation rate between cultures of specimens obtained from the maxillary sinus and from the middle meatus in all 24 animals. In addition, the quantitative counts from the middle meatus and the maxillary sinus correlated. Control animals showed no bacterial growth from either the middle meatus or the maxillary sinus. These results show that, in an animal model of acute sinusitis, cultures of specimens from the middle meatus reflect the contents of the maxillary sinus.

Effect of platelet-activating factor on the mucocillary transport of the maxillary sinus in rabbits

Effect of platelet-activating factor on the mucocillary transport of the maxillary sinus in rabbits