RESUMO
This work aims to contribute to the knowledge of human cementum protein 1 (CEMP1), its conformational characteristics and influence during the biomineralization process. The results revealed that hrCEMP1 expressed in Pichia pastoris is a 2.4% glycosylated, thermostable protein which possesses a molecular mass of 28,770 Da. The circular dichroism spectrum indicated a secondary structure content of 28.6% of alpha-helix, 9.9% of beta-sheet and 61.5% of random-coil forms. Biological activity assays demonstrated that hrCEMP1 nucleates and regulates hydroxyapatite crystal growth. Hereby, it is demonstrated for the first time that CEMP1 has a (C-type) lectin-like activity and specifically recognizes mannopyranoside. The information produced by this biochemical and structural characterization may contribute to understand more fully the biological functions of CEMP1.
Assuntos
Regulação Fúngica da Expressão Gênica , Lectinas/metabolismo , Pichia/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas/metabolismo , Animais , Dicroísmo Circular , Agregação Eritrocítica/efeitos dos fármacos , Glicosilação , Temperatura Alta/efeitos adversos , Humanos , Hidroxiapatitas/química , Hidroxiapatitas/metabolismo , Lectinas/química , Lectinas/genética , Lectinas/farmacologia , Manose/química , Manose/metabolismo , Microscopia Eletrônica de Varredura , Peso Molecular , Conformação Proteica , Estabilidade Proteica , Estrutura Secundária de Proteína , Proteínas/química , Proteínas/genética , Proteínas/farmacologia , Coelhos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The interest around bioactive glass-ceramics (GCs) has grown significantly over the last two decades due to their appropriate biochemical and mechanical properties. The intense research effort in this field has led to some new commercial products for biomedical applications. This review article begins with the basic concepts of GC processing and development via controlled heat treatments of monolithic pieces or sinter-crystallization of powdered glasses. We then go on to describe the processing, properties, and applications of some commercial bioactive GCs and discuss selected valuable reported researches on several promising types of bioactive GCs. The article finishes with a section on open relevant research directions for bioactive GC development.
Assuntos
Materiais Biocompatíveis/química , Cerâmica/química , Alicerces Teciduais/química , Animais , Materiais Biocompatíveis/metabolismo , Cerâmica/metabolismo , Vidro/química , Humanos , Hidroxiapatitas/química , Hidroxiapatitas/metabolismo , Teste de Materiais , Próteses e ImplantesRESUMO
This work aims to evaluate the cytocompatibility of injectable and moldable restorative biomaterials based on granules of dense or porous biphasic calcium phosphates (BCPs) with human primary mesenchymal cells, in order to validate them as tools for stem cell-induced bone regeneration. Porous hydroxyapatite (HA) and HA/beta-tricalcium phosphate (ß-TCP) (60:40) granules were obtained by the addition of wax spheres and pressing at 20 MPa, while dense materials were compacted by pressing at 100 MPa, followed by thermal treatment (1100°C), grinding, and sieving. Extracts were prepared by 24-h incubation of granules on culture media, with subsequent exposition of human primary mesenchymal cells. Three different cell viability parameters were evaluated on the same samples. Scanning electron microscopy analysis of the granules revealed distinct dense and porous surfaces. After cell exposition to extracts, no significant differences on mitochondrial activity (2,3-bis(2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) or cell density (Crystal Violet Dye Elution) were observed among groups. However, Neutral Red assay revealed that dense materials extracts induced lower levels of total viable cells to porous HA/ß-TCP (P < 0.01). Calcium ion content was also significantly lower on the extracts of dense samples. Porogenic treatments on BCP composites do not affect cytocompatibility, as measured by three different parameters, indicating that these ceramics are well suited for further studies on future bioengineering applications.
Assuntos
Materiais Biocompatíveis/metabolismo , Hidroxiapatitas/metabolismo , Células-Tronco Mesenquimais/citologia , Materiais Biocompatíveis/química , Sobrevivência Celular , Células Cultivadas , Humanos , Hidroxiapatitas/química , Células-Tronco Mesenquimais/metabolismo , Mitocôndrias/metabolismo , PorosidadeRESUMO
OBJECTIVE: The aim of this study was to assess, through near-infrared Raman spectroscopy (NIRS), the incorporation of hydroxyapatite of calcium (CHA; approximately 960 cm(1))--on the healing bone around dental implants submitted or not to low-level laser therapy (LLLT) (lambda830 nm). BACKGROUND DATA: The process of maturation of the bone is important for the success of dental implants, as it improves the fixation of the implant to the bone, allowing the wearing of a prosthesis. LLLT has been suggested as a mean of improving bone healing because of its biomodulatory capabilities. METHODS: Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with lambda830-nm laser (seven sessions at 48-h intervals, 21.5 J/cm(2) per session, 10 mW, phi approximately 0.0028 cm(2), 85 J/cm(2) treatment dose), and six acted as control. The animals were sacrificed at 15, 30, and 45 days after surgery. Specimens were routinely prepared for Raman spectroscopy. Twelve readings were taken on the bone around the implant. RESULTS: The results showed significant differences in the concentration of CHA on irradiated and control specimens at both 30 and 45 days after surgery (p < 0.001). CONCLUSION: It is concluded that LLLT does improve bone healing, and this can be safely assessed by Raman spectroscopy.
Assuntos
Implantes Dentários , Lasers , Osseointegração/efeitos da radiação , Análise Espectral Raman , Animais , Materiais Revestidos Biocompatíveis/metabolismo , Hidroxiapatitas/metabolismo , Masculino , Coelhos , Tíbia/cirurgia , TitânioRESUMO
Materials and devices intended for end-use applications as implants and medical devices must be evaluated to determine their biocompatibility potential in contact with physiological systems. The use of standard practices of biological testing provides a reasonable level of confidence concerning the response of a living organism to a given material or device, as well as guidance in selecting the proper procedures to be carried out for the screening of new or modified materials. This article presents results from cytotoxicity assays of cell culture, skin irritation, and acute toxicity by systemic and intracutaneous injections for powders, ceramic bodies, and extract liquids of hydroxyapatite (HA), calcia partially stabilized zirconia (ZO), and two types of zirconia-hydroxyapatite composites (Z4H6 and Z6H4) with potential for future use as orthopedic and dental implants. They indicate that these materials present potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity of ATCC cell cultures (CCL1 NCTC clone 929 of mouse connective tissue and CCL 81 of monkey connective tissue) and animals (rabbit and mouse) with direct or indirect patient contact, or by the injection of specific extracts prepared from the material under test. In addition, studies involving short-term intramuscular and long-term implantation assays to estimate the reaction of living tissue to the composites studied, and investigations on long-term effects that these materials can cause on the cellular metabolism, are already in progress.
Assuntos
Materiais Biocompatíveis , Ligas Dentárias/toxicidade , Reação a Corpo Estranho , Hidroxiapatitas/toxicidade , Zircônio/toxicidade , Animais , Linhagem Celular , Haplorrinos , Humanos , Hidroxiapatitas/administração & dosagem , Hidroxiapatitas/metabolismo , Teste de Materiais , Camundongos , Próteses e Implantes , Coelhos , Testes de Toxicidade , Zircônio/administração & dosagem , Zircônio/metabolismoRESUMO
Major problems with the treatment of osteomyelitis are associated with poor antibiotic distribution at the site of infection due to limited blood circulation to the skeletal tissue. Improved treatment procedures have been used in drug delivery systems that include bioceramics and natural and synthetic polymers. This work reports the development of anionic collagen:hydroxyapatite composite paste for sustained antibiotic release. Antibiotic release by the composite was characterized by two steps. In the first, 15.0+/-4.9% was released in the first 5 h (n = 53) by a normal Fick diffusion mechanism. In the second step, only 16.8+/-2.2% was released after 7 days. In conclusion, hydroxyapatite:anionic collagen composite can be an efficient support for sustained antibiotic release in the treatment of osteomyelitis because most of the antibiotic release may be associated with composite bioresorption, thus permitting antibiotic release throughout the healing process. Hydroxyapatite:anionic collagen paste showed good biocompatibility associated with bone tissue growth with material still being observed after 60 days from the time of implants.