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Record 1301 to 1320

Chitosan nanoparticles as a novel delivery system for ammonium glycyrrhizinate
Wu, Y., W. Yang, et al. (2005), Int J Pharm 295(1-2): 235-45.
Abstract: The ammonium glycyrrhizinate-loaded chitosan nanoparticles were prepared by ionic gelation of chitosan with tripolyphosphate anions (TPP). The particle size and zeta potential of nanoparticles were determined, respectively, by dynamic light scattering (DLS) and a zeta potential analyzer. The effects, including chitosan molecular weight, chitosan concentration, ammonium glycyrrhizinate concentration and polyethylene glycol (PEG) on the physicochemical properties of the nanoparticles were studied. These nanoparticles have ammonium glycyrrhizinate loading efficiency. The encapsulation efficiency decreased with the increase of ammonium glycyrrhizinate concentration and chitosan concentration. The introduction of PEG can decrease significantly the positive charge of particle surface. These studies showed that chitosan can complex TPP to form stable cationic nanoparticles for subsequent ammonium glycyrrhizinate loading.

Chitosan oligosaccharide inhibits 203HgCl2-induced genotoxicity in mice: micronuclei occurrence and chromosomal aberration
Yoon, H. J., H. S. Park, et al. (2005), Arch Pharm Res 28(9): 1079-85.
Abstract: The purpose of this study was to investigate the safety of chitosan oligosaccharide and the effects of chitosan oligosaccharide on mercury induced genotoxicity in mice using the micronuclei and chromosome aberration. The micronuclei test was performed by microscopic examination (x1,000, stained using a May-Grunwald solution) after administering 0.01, 0.1, and 1% (10 mg/mL) chitosan oligosaccharide for 7, 60, and 180 days ad libitum in mice. Total micronuclei of 1,000 polychromatic erythrocytes were recorded for each group. There was no difference between the untreated and experimental groups. The intake periods and concentrations of chitosan oligosaccharide did not affect the occurrence of micronuclei in bone marrow cells (P>0.05). The chromosomal aberration test was performed by microscopic examination (x1,000, stained using a 4% Giemsa solution) after administering the same concentration of chitosan oligosaccharide to mice, in F1, F2, F3 generations and parents. The frequency of chromosomal aberrations was defined as [Ydr = (D+R)/total number of counted lymphocytes]. Similar to the micronuclei test, there was no difference between the untreated and treated groups. These results showed that the intake periods and concentrations of chitosan oligosaccharide did not affect chromosomal aberrations in bone marrow cells (P>0.05). To investigate the effect of chitosan oligosaccharide on mercury-induced chromosome aberration, mice in each condition were supplied with 203HgCl2 and chitosan oligosaccharide ad libitum. Chitosan oligosaccharide significantly inhibited 203HgCl2-induced chromosome aberration in mice. Based on the results of this study, it may be concluded that the chitosan oligosaccharide is a nontoxic material that could be used as a suppressor of heavy metal-induced genotoxicity.

Chitosan/beta-lactoglobulin core-shell nanoparticles as nutraceutical carriers
Chen, L. and M. Subirade (2005), Biomaterials 26(30): 6041-53.
Abstract: Chitosan (CS)/beta-lactoglobulin (betalg) core-shell nanoparticles (CS-betalg nanoparticle) were successfully prepared with the aim of developing a biocompatible carrier for the oral administration of nutraceuticals. The effects of pH and initial concentrations (C(beta)(lg)) of native and denatured betalg on the properties of the nanoparticles were investigated. Uniform nanoparticles were prepared by ionic gelation with sodium tripolyphosphate (TPP). The surface charge of the particles was positive, with a zeta potential of 20-60 mV. (beta)lg loading efficiency (LE) spanned a broad range (1-60%); and was highly sensitive to formulation pH. This adsorption can be mainly attributed to electrostatic, hydrophobic interactions and hydrogen bonding between (beta)lg and CS. Brilliant blue (BB) release experiments showed that the nanoparticles prepared with native (beta)lg had favorable properties to resist acid and pepsin degradation in simulated gastric conditions unlike those prepared with denatured (beta)lg or denatured (beta)lg crosslinked with Ca2+. When transferred to simulated intestinal conditions, the (beta)lg shells of the nanoparticles were degraded by pancreatin.

Chitosan/cellulose acetate microspheres preparation and ranitidine release in vitro
Zhou, H. Y., X. G. Chen, et al. (2005), Pharm Dev Technol 10(2): 219-25.
Abstract: New microspheres containing hydrophilic core and hydrophobic coating as a controlled-release system with no toxic reagents were proposed. Water in oil in water (W/O/W) emulsion and solvent evaporation methods were used to make chitosan/ cellulose acetate (CCA) microspheres sized 200 - 400 microm. Ranitidine hydrochloride, as a model drug, was investigated for its release properties in vitro. The loading efficiency and release rate of ranitidine were affected by chitosan concentration and molecular weight. Higher loadings were obtained at lower concentrations in the interval of 1% to 2%. With chitosan at a 2% concentration microspheres could be obtained with more spherical appearance, smaller size, and higher ranitidine loading efficiency microspheres than at other concentrations. Among the different molecular weight chitosan (47, 145, 308, 499, and 1130 KD) microspheres, the high molecular weight chitosan (1130 KD) microspheres had relatively high loading efficiency (10%). Molecular weight and concentration of chitosan as well as the size of microspheres affected the release of ranitidine. Microspheres smaller than 280 microm released the drug faster than did the bigger by about 10%. The optimal condition for the preparation of the microspheres was chitosan concentration 2%, molecular weight 1130 KD. The ranitidine release from the microspheres was 30% during 48 h in phosphate-buffer saline medium.

Chitosan: a versatile biomaterial
Yilmaz, E. (2004), Adv Exp Med Biol 553: 59-68.

Chitosan: a versatile biopolymer for orthopaedic tissue-engineering
Di Martino, A., M. Sittinger, et al. (2005), Biomaterials 26(30): 5983-90.
Abstract: Current tissue engineering strategies are focused on the restoration of pathologically altered tissue architecture by transplantation of cells in combination with supportive scaffolds and biomolecules. In recent years, considerable attention has been given to chitosan (CS)-based materials and their applications in the field of orthopedic tissue engineering. Interesting characteristics that render chitosan suitable for this purpose are a minimal foreign body reaction, an intrinsic antibacterial nature, and the ability to be molded in various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. Due to its favorable gelling properties chitosan can deliver morphogenic factors and pharmaceutical agents in a controlled fashion. Its cationic nature allows it to complex DNA molecules making it an ideal candidate for gene delivery strategies. The ability to manipulate and reconstitute tissue structure and function using this material has tremendous clinical implications and is likely to play a key role in cell and gene therapies in coming years. In this paper we will review the current applications and future directions of CS in articular cartilage, intervertebral disk and bone tissue engineering.

Chitosan-alginate as scaffolding material for cartilage tissue engineering
Li, Z. and M. Zhang (2005), J Biomed Mater Res A 75(2): 485-93.
Abstract: Tissue compatibility of chitosan-alginate scaffolds was studied in vitro in terms of cell morphology, proliferation, and functionality using HTB-94 cells. The scaffold has an interconnected 3D porous structure, and was fabricated by thermally induced phase separation followed by freeze drying. Cell proliferation on the chitosan-alginate scaffold was found to be faster than on a pure chitosan scaffold. After cell culture for 2 weeks in vitro, the cells on the chitosan scaffold gradually assumed a fibroblast-like morphology while the cells on the chitosan-alginate scaffold retained their spherical morphology throughout the period of study. SDS-PAGE electrophoresis and Western blot assays for proteins extracted from cells grown on scaffolds indicated that production of cartilage-specific collagen type II, a marker for chondrocytic phenotype, increased from week 2 to week 3 on the chitosan-alginate scaffold but decreased on the chitosan scaffold. This study suggested that chitosan-alginate scaffolds promote cell proliferation, enhance phenotype expression of HTB-94 chondrocytes, and may potentially serve as an improved alternative to chitosan scaffolds for cartilage tissue engineering.

Chitosan--as a biomaterial
Chandy, T. and C. P. Sharma (1990), Biomater Artif Cells Artif Organs 18(1): 1-24.
Abstract: Chitosan [a (1----4) 2-amino-2-deoxy-beta-D-Glucan] is a unique polysaccharide derived from chitin. Several attempts have been made to use this biopolymer in biomedical field. The use of this material in the development of hemodialysis membranes, artificial skin, drug targetting and other applications are discussed. It appears, this novel biomolecule, biodegradable, and biocompatible, find applications in substituting or regenerating the blood/tissue interfaces. This polysaccharide having structural characteristics similar to glycosaminoglycans, seems to mimic their functional behaviour.

Chitosan-based particles as controlled drug delivery systems
Prabaharan, M. and J. F. Mano (2005), Drug Deliv 12(1): 41-57.
Abstract: Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for conventional and novel drug delivery systems. This article reviews the approaches aimed to associate bioactive molecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan forms colloidal particles and entraps bioactive molecules through a number of mechanisms, including chemical crosslinking, ionic crosslinking, and ionic complexation. A possible alternative of chitosan by the chemical modification also has been useful for the association of bioactive molecules to polymer and controlling the drug release profile. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations. This review also examines the advances in the application of chitosan and its derivatives to nonviral gene delivery and gives an overview of transfection studies that use chitosan as a transfection agent. From the studies reviewed, we concluded that chitosan and its derivatives are promising materials for controlled drug and nonviral gene delivery.

Chitosan-cholesterol and chitosan-stearic acid interactions at the air-water interface
Parra-Barraza, H., M. G. Burboa, et al. (2005), Biomacromolecules 6(5): 2416-26.
Abstract: We report in this work the isotherms of cholesterol and stearic acid at the air-water interface modified by different chitosans (chitosan chloride, hydrophobic modified chitosan, and medium and high molecular weight chitosans) in the aqueous subphase. The Langmuir-Blodgett films of the complexes cholesterol-chitosan and stearic acid-chitosan are analyzed by atomic force microscopy (AFM), and a molecular simulation was performed to visualize the chitosan-lipid interactions. Strong modifications are obtained in the isotherms as a result of the chitosan interactions with cholesterol and stearic acid at the air-water interface. These modifications were dependent on the type and concentration of chitosan. Severe modifications of all phases were noticed with larger molecular areas, and the observed changes in the compressional modulus were dependent on the type of chitosan used. The complexes of chitosan-stearic acid were more flexible than the ones of chitosan-cholesterol. The AFM images demonstrated that chitosan was disaggregated by the cholesterol and stearic acid interactions producing more homogeneous surfaces in some cases. The hydrophobic chitosan showed more affinity with stearic acid, while both medium and high molecular weight chitosans produced homogeneous surfaces with cholesterol. The simulated chitosan chains interacting with cholesterol and stearic acid demonstrated the possibility of specific sites of electrostatic bonds between these molecules. Adsorption of cholesterol on the different powdered chitosans, performed by HPLC, showed that the medium and high molecular weight chitosans could retain higher proportions of cholesterol compared with the other analyzed samples.

Chitosan-DNA microparticles as mucosal delivery system: synthesis, characterization and release in vitro
Li, Y. H., M. W. Fan, et al. (2005), Chin Med J (Engl) 118(11): 936-41.
Abstract: BACKGROUND: Mucosal immunity is important to defense against dental caries. To enhance mucosal immunity, a DNA vaccine mucosal delivery system was prepared by encapsulating anticaries DNA vaccine (plasmid pGJA-P/VAX) in chitosan under optimal conditions and the characteristics of the microparticles was investigated. Furthermore, the release properties and protective action of microparticles for plasmid were studied in vitro. METHODS: Plasmid loaded chitosan microparticles were prepared by complex coacervation. Three factors, concentration of DNA, sodium sulfate, and the chitosan/DNA ratios in complexes [better expressed as N/P ratio: the number of poly nitrogen (N) per DNA phosphate (P)] influencing preparation were optimized by orthogonal test. The characteristics of microparticles were evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). DNA release rate of microparticles in similar gastro fluid (SGF) or similar intestinal fluid (SIF) at 37 degrees C was determined by ultraviolet spectrophotometry. RESULTS: High encapsulation efficiency (96.8%) was obtained with chitosan microparticles made under optimal conditions of 50 mmol/L Na2SO4, 200 microg/ml DNA and N/P ratio of 4. The size of particles was about 4 to 6 microm. The encapsulation process did not destroy the integrity of DNA. When incubated with SIL, after a release of about 10% in the first 60 minutes, no further DNA was released during the following 180 minutes. When incubated with SGL, the microparticles released a small burst (about 11%) in the first 60 minutes, and then slowly released at a constant, but different rate. CONCLUSIONS: These chitosan microparticles showed suitable characteristics in vitro for mucosal vaccination and are therefore a promising carrier system for DNA vaccine mucosal delivery.

Chitosan-reinforced alginate microspheres obtained through the emulsification/internal gelation technique
Ribeiro, A. J., C. Silva, et al. (2005), Eur J Pharm Sci 25(1): 31-40.
Abstract: Alginate microspheres prepared by emulsification/internal gelation were chosen as carriers for a model protein, hemoglobin (Hb). Reinforced chitosan-coated microspheres were obtained by an uninterrupted method, in order to simplify the coating process, minimize protein losses during production and to avoid Hb escape under acidic conditions. Microspheres recovery was evaluated as well as its morphology by determination of Hb encapsulation efficiency and microscopic observation, respectively. The formation of chitosan membrane made of it interaction with alginate was assessed by DSC (differential scanning calorimetry) and FT-IR (Fourier-transform infrared spectrometry) studies. Spherical uncoated microspheres with a mean diameter of 20 microm and encapsulation efficiency above 89% were obtained. Coated microspheres provided similar encapsulation efficiency but a higher mean diameter was obtained due to microspheres clumping during the coating step. Protein loss occurred mainly during emulsification rather than recovery. FT-IR and DSC together indicated electrostatic interactions between alginate carboxylate and chitosan ammonium groups as the main forces for complex formation. Hb release from microspheres showed a pH-dependent profile and was affected by chitosan coating. Under simulated gastric conditions, a total Hb burst release from uncoated microspheres was decreased with one-stage and two-stage chitosan coatings (68% and 28%, respectively). At pH 6.8, the Hb release from coated microspheres was fast but incomplete. These results suggest an optimization of the coating method to protect Hb under acidic conditions and to permit a complete but sustained release of Hb.

Chitosan-RGDSGGC conjugate as a scaffold material for musculoskeletal tissue engineering
Masuko, T., N. Iwasaki, et al. (2005), Biomaterials 26(26): 5339-47.
Abstract: In the present study, we have developed a novel and versatile method for the preparation of chitosan-peptide complex based on the selective reaction of chitosan with 2-iminothiolane. The new type of SH-chitosan derivative showed an excellent solubility to aqueous solution even in the alkaline conditions. This characteristic greatly facilitated further modification study of chitosan with a variety of bioactive substances. A synthetic peptide, RGDSGGC containing RGDS moiety that is known as one of the most important cell adhesive peptides, was readily coupled by disulfide bonds formation with sulfhydryl groups of SH-chitosan in the presence of dimethyl sulfoxide. Next, the effect of the introduction of RGDSGGC moiety to chitosan on cell adhesion and proliferation activity of chondrocytes and fibroblasts were evaluated. As a result, it was suggested that this polysaccharide-peptide conjugate exhibited excellent capacities for both cell adhesion and cell proliferation of chondrocytes and fibroblasts. Considering the growing importance of the biocompatible scaffolds in the recent tailored tissue engineering technique, these results indicate that the present strategy of 2-iminothiolane-based conjugation of polysaccharides with biologically active peptides will become a key and potential technology to develop desirable scaffold materials for the tissue regenerations.

Chitosan-tethered poly(acrylonitrile-co-maleic acid) hollow fiber membrane for lipase immobilization
Ye, P., Z. K. Xu, et al. (2005), Biomaterials 26(32): 6394-403.
Abstract: A protocol was used to prepare a dual-layer biomimetic membrane as support for enzyme immobilization by tethering chitosan on the surface of poly(acrylonitrile-co-maleic acid) (PANCMA) ultrafiltration hollow fiber membrane in the presence of 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxylsuccin-imide (NHS). The chemical change of the chitosan-modified PANCMA membrane surface was confirmed with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Lipase from Candida rugosa was immobilized on this dual-layer biomimetic membrane using glutaraldehyde (GA), and on the nascent PANCMA membrane using EDC/NHS as coupling agent. The properties of the immobilized enzymes were assayed and compared with those of the free one. It was found that both the activity retention of the immobilized lipase and the amount of bound protein on the dual-layer biomimetic membrane (44.5% and 66.5 mg/m2) were higher than those on the nascent PANCMA membrane (33.9% and 53.7 mg/m2). The kinetic parameters of the free and immobilized lipases, Km and Vmax, were also assayed. The Km values were similar for the immobilized lipases, while the Vmax value of the immobilized lipase on the dual-layer biomimetic membrane was higher than that on the nascent PANCMA membrane. Results indicated that the pH and thermal stabilities of lipase increased upon immobilization. The residual activity of the immobilized lipase after 10 uses was 53% on the dual-layer biomimetic membrane and 62% on the nascent PANCMA membrane.

Chlorhexidine-releasing methacrylate dental composite materials
Leung, D., D. A. Spratt, et al. (2005), Biomaterials 26(34): 7145-53.
Abstract: Light curable antibacterial, dental composite restoration materials, consisting of 80 wt% of a strontium fluoroaluminosilicate glass dispersed in methacrylate monomers have been produced. The monomers contained 40-100 wt% of a 10 wt% chlorhexidine diacetate (CHXA) in hydroxyethylmethacrylate (HEMA) solution and 60-0 wt% of a 50/50 mix of urethane dimethacrylate (UDMA) and triethyleneglycol dimethacrylate (TEGDMA). On raising HEMA content, light cure polymerisation rates decreased. Conversely, water sorption induced swelling and rates of diffusion controlled CHXA release from the set materials increased. Experimental composites with 50 and 90 wt% of the CHXA in HEMA solution in the monomer were shown, within a constant depth film fermentor (CDFF), to have slower rates of biofilm growth on their surfaces between 1 and 7 days than the commercial dental composite Z250 or fluoride-releasing dental cements, Fuji II LC and Fuji IX. When an excavated bovine dentine cylinder re-filled with Z250 was placed for 10 weeks in the CDFF, both bacteria and polymers from the artificial saliva penetrated between the material and dentine. With the 50 wt% experimental HEMA/CHXA formulation, this bacterial microleakage was substantially reduced. Polymer leakage, however, still occurred. Both polymer and bacterial microleakage were prevented with a 90 wt% HEMA/CHXA restoration in the bovine dentine due to swelling compensation for polymerisation shrinkage in combination with antibacterial release.

Chromatin organization measured by AluI restriction enzyme changes with malignancy and is regulated by the extracellular matrix and the cytoskeleton
Maniotis, A. J., K. Valyi-Nagy, et al. (2005), Am J Pathol 166(4): 1187-203.
Abstract: Given that expression of many genes changes when cells become malignant or are placed in different microenvironments, we asked whether these changes were accompanied by global reorganization of chromatin. We reasoned that sequestration or exposure of chromatin-sensitive sites to restriction enzymes could be used to detect this reorganization. We found that AluI-sensitive sites of nonmalignant cells were relatively more exposed compared to their malignant counterparts in cultured cells and human tumor samples. Changes in exposure and sequestration of AluI-sensitive sites in normal fibroblasts versus fibrosarcoma or those transfected with oncogenes, nonmalignant breast cells versus carcinomas and poorly metastatic versus highly invasive melanoma were shown to be independent of the cell cycle and may be influenced by proteins rich in disulfide bonds. Remarkably, regardless of degree of malignancy, AluI-sensitive sites became profoundly sequestered when cells were incubated with laminin, Matrigel, or a circular RGD peptide (RGD-C), but became exposed when cells were placed on collagen I or in serum-containing medium. Disruption of the actin cytoskeleton led to exposure, whereas disruption of microtubules or intermediate filaments exerted a sequestering effect. Thus, AluI-sensitive sites are more sequestered with increasing malignant behavior, but the sequestration and exposure of these sites is exquisitely sensitive to information conferred to the cell by molecules and biomechanical forces that regulate cellular and tissue architecture.

Chronic antithrombogenic biomaterials screen
Lubin, M., T. Nappholz, et al. (1986), Pacing Clin Electrophysiol 9(6 Pt 2): 1154-9.
Abstract: The widespread usage of chronic implantable sensors in cardiac device systems has been hampered by both sensor technology issues and the lack of surface passivations with chronic antithrombogenic capabilities. In this study, dummy pacing leads with six types of passivations were implanted for 17 weeks in 36 dogs to assess thrombogenic character, degree of tissue growth and encapulation, and general performance in providing optically clear windows into the blood or body tissues. Asceptic surgical procedures were used and complete blood work-up was performed every two weeks postop. Two dogs served as surgical shams to monitor system artifacts. At explant the devices fairly clearly divided themselves into two groups based on the percent of exposed surface area covered by gross macroscopic tissue accumulations. There were three passivated types in each group. Scanning electron microscopy (SEM) and energy dispersive analysis of x-rays (EDAX) techniques were used to investigate further the samples from the three passivation types that performed "better" based on percent surface area analysis. Issues that became prominent were substrate surface finish and topography, and some mineralization phenomena. Some of the evidence raises the possibility that processes that provide chronic antithrombogenic performance might also enhance mineralization or propensity toward natural breakdown processes. These questions are now being more closely addressed in follow-up studies now in progress.

Cleavage of disulfide-linked fetuin-bisphosphonate conjugates with three physiological thiols
Zhang, S., J. E. Wright, et al. (2005), Biomacromolecules 6(5): 2800-8.
Abstract: An effective therapeutic agent for treatment of bone diseases is expected to exhibit a high affinity to bone. Conjugating proteins to bisphosphonates (BPs), a class of molecules with an exceptional affinity to bone mineral hydroxyapatite (HA), is a feasible means to impart such a bone affinity. Protein-BP conjugates with cleavable linkages, which allow protein release from the mineral, are preferable over conjugates with stable linkages. To this end, 2-(3-mercaptopropylsulfanyl)-ethyl-1,1-bisphosphonic acid (thiolBP) was conjugated onto fetuin, a model protein, using N-succinimidyl-3-(2-pyridyldithio)propionate to create disulfide-linked conjugates. Although the fetuin-thiolBP conjugates were stable under aqueous conditions, the disulfide linkage was readily cleaved in the presence of the physiological thiols l-cysteine, dl-homocysteine, and l-glutathione. dl-Homocysteine exhibited the highest cleavage of the disulfide linkage among these thiols. The imparted bone affinity as a result of thiolBP conjugation, as assessed by HA binding in vitro, was eliminated upon cleavage of the disulfide linkage. The cleavage of the conjugates bound to HA was as effective as the conjugate cleavage in solution, and even more so at high concentrations of l-glutathione. In conclusion, disulfide-linked fetuin-thiolBP conjugates exhibited a high affinity to HA, which was readily lost upon cleavage with thiols found in physiological milieu.

Clinical and histologic analysis of calcium sulfate in treatment of a post-extraction defect: a case report
Sbordone, L., C. Bortolaia, et al. (2005), Implant Dent 14(1): 82-7.
Abstract: We report a case of a postextraction maxillary buccal dehiscence grafted with calcium sulfate to insert a dental implant. The clinical results were supported by histologic analysis of two specimens collected in the healed socket to better understand the biologic effects of calcium sulfate. A 42-year-old white female presented with an almost totally edentulous maxillary right arch with a wide postextraction defect in the canine region. Calcium sulfate mixed with sterile saline solution to a putty-like consistency was packed into the defect, and four dental implants were placed in the edentulous ridge. On re-entry, a dental implant and small amounts of calcium sulfate were placed in the grafted site. After 5 months, a specimen of the region implanted with calcium sulfate was retrieved for histologic evaluation. On surgical re-entry, a complete filling of the defect with mature, dense, newly formed bone occurred. Complete resorption of the grafted material and its substitution with newly formed bone tissue were confirmed by histologic analysis. All of the implants appeared to be osseointegrated successfully, and the patient was provided with a fixed implant-supported prosthesis. Calcium sulfate represents an aid in bone regeneration procedures.

Clinical and histologic evaluation of an enamel matrix protein derivative combined with a bioactive glass for the treatment of intrabony periodontal defects in humans
Sculean, A., P. Windisch, et al. (2005), Int J Periodontics Restorative Dent 25(2): 139-47.
Abstract: The present study clinically and histologically evaluated healing of human intrabony defects following treatment with a combination of enamel matrix derivative (EMD) and bioactive glass (BG) or BG alone. Six patients displaying either combined one- and two-walled (five patients) or three-walled (one patient) intrabony defects around teeth scheduled for extraction were included. A notch was placed at the most apical extent of the calculus on the root surface to serve as a reference. Six months after surgery, the teeth or roots were extracted, together with some of their surrounding soft and hard tissues, and processed for histologic evaluation; a gain of clinical attachment was found in all cases. Healing in all three defects treated with EMD + BG was mainly characterized by new cementum with inserting collagen fibers and new periodontal ligament; most graft particles were surrounded by bone-like tissue, indicating ongoing mineralization. Treatment with BG resulted in epithelial down-growth and connective tissue encapsulation of the graft material in all three specimens. Reformation of cementum and periodontal ligament was observed in one of the specimens, limited to the most apical part of the defect. Formation of bone-like tissue around the graft particles was observed in only one of the three specimens treated with BG. Direct contact between the BG particles and root surface (cementum or dentin) was not observed in any of the six specimens. BG alone has low potential to facilitate periodontal regeneration. However, EMD + BG resulted in formation of new cementum with an associated periodontal ligament, as well as enhanced mineralization around the BG particles.

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