RESUMO
A new method for the analysis and design of fiber Bragg gratings (FBGs) based on the theory of transmission lines has been developed and verified both theoretically and experimentally. The method is an extension of the coupled-mode theory and utilizes the equivalent transmission lines in order to simulate any type of grating, with an easy and direct implementation. The method provides the ability to analyze the optical devices without using full wave approaches, while also facilitating the incorporation of core materials with a complex or non-linear refractive index, non-uniform distributions of the grating's refractive index, and tilted and phase-shifted gratings. The approach also allows the design of the grating for a given reflection spectra. Numerical results of the method's application on a randomly varied inscription of the refractive index of a FBG have also been simulated and discussed. Using this method, the characteristics of an erbium-doped (ED)-FBG have been simulated and the predictions verified experimentally.
RESUMO
Cell osmoporation is a simple and straightforward procedure of creating food-grade biocapsules. This study proposes a new protocol of sequential cell osmoporation stages and evaluates its impact on the efficiency of curcumin and fisetin internalization into Saccharomyces cerevisiae cells. To the best of our knowledge, this is the first report in the literature regarding the subject. To assess how multiple osmoporation stages influence the encapsulation efficiency (% EE), encapsulated amount of curcumin (IC) and fisetin (IF) into S. cerevisiae cells and cell viability, the residual supernatant was used for the subsequent encapsulation stages and viability was assessed by the CFU method. Quantification was carried through direct extraction, using an ultrasonic bath and UV-Vis spectrophotometry. Experimental data demonstrated that the addition of a second osmoporation stage increases both the EE (% EE) and the amount of encapsulated curcumin and fisetin (IC and IF). As a result, the EE was considerably improved and the obtained microcapsules contained a higher amount of the targeted bioactive compounds in its internal structure. However, adding a third osmoporation stage proved to less beneficial to the process efficiency due to its lower yield and the significant negative impact to cell viability. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time in the literature, a protocol of serial osmoporation stages to enhance the encapsulation efficiency of hydrophobic low molecular weight molecules (curcumin and fisetin) into Saccharomyces cerevisiae cells was determined. By increasing overall efficiency, this protocol empowers the encapsulation process and creates a rational way to reduce waste for future industrial osmoporation applications.
Assuntos
Transporte Biológico/fisiologia , Curcumina/metabolismo , Flavonoides/metabolismo , Osmose/fisiologia , Saccharomyces cerevisiae/metabolismo , Cápsulas , Sobrevivência Celular , Flavonóis , Interações Hidrofóbicas e HidrofílicasRESUMO
Atrophic gastritis, intestinal metaplasia, and epithelial dysplasia of the stomach are common and are associated with an increased risk for gastric cancer. In the absence of guidelines, there is wide disparity in the management of patients with these premalignant conditions. The European Society of Gastrointestinal Endoscopy (ESGE), the European Helicobacter Study Group (EHSG), the European Society of Pathology (ESP) and the Sociedade Portuguesa de Endoscopia Digestiva (SPED) have therefore combined efforts to develop evidence-based guidelines on the management of patients with precancerous conditions and lesions of the stomach (termed MAPS). A multidisciplinary group of 63 experts from 24 countries developed these recommendations by means of repeat online voting and a meeting in June 2011 in Porto, Portugal. The recommendations emphasize the increased cancer risk in patients with gastric atrophy and metaplasia, and the need for adequate staging in the case of high grade dysplasia, and they focus on treatment and surveillance indications and methods.
Assuntos
Mucosa Gástrica/patologia , Gastrite Atrófica/patologia , Gastrite Atrófica/terapia , Lesões Pré-Cancerosas/patologia , Lesões Pré-Cancerosas/terapia , Neoplasias Gástricas/patologia , Biópsia , Medicina Baseada em Evidências , Gastrite Atrófica/diagnóstico , Gastroscopia , Infecções por Helicobacter/tratamento farmacológico , Infecções por Helicobacter/economia , Infecções por Helicobacter/microbiologia , Helicobacter pylori , Humanos , Metaplasia/patologia , Metaplasia/terapia , Pepsinogênios/sangue , Vigilância da População , Lesões Pré-Cancerosas/diagnósticoRESUMO
Composites filled with a silicate glass (CSi) and a new borate glass (CB) were developed and compared in terms of their in vitro behaviour both in acellular and cellular media. Acellular tests were carried out in SBF and the composites were characterized by SEM-EDS, XRD and ICP. Biocompatibility studies were investigated by in vitro cell culture with MG-63 osteoblast-like and human bone marrow cells. The growth of spherical calcium phosphate aggregates was observed in acellular medium on all composite surfaces indicating that these materials became potentially bioactive. The biological assessment resulted in a dissimilar behavior of the composites. The CSi demonstrated an inductive effect on the proliferation of cells. The cells showed a normal morphology and high growth rate when compared to standard culture plates. Contrarily, inhibition of cell proliferation occurred in the CB probably due to its high degradation rate, leading to high B and Mg ionic concentration in the cell culture medium.
Assuntos
Resinas Acrílicas/farmacologia , Boratos/farmacologia , Resinas Compostas/farmacologia , Vidro , Poliuretanos/farmacologia , Silicatos/farmacologia , Resinas Acrílicas/química , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/fisiologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Resinas Compostas/química , Restauração Dentária Permanente , Vidro/química , Humanos , Teste de Materiais/métodos , Metilmetacrilatos/química , Metilmetacrilatos/farmacologia , Microscopia Eletrônica de Varredura , Osteoblastos/efeitos dos fármacos , Osteoblastos/fisiologia , Poliuretanos/químicaRESUMO
Emamectin benzoate (Affirm) is a novel insecticide with potent efficacy against many specie of lepidoptera which are damaging fruits and leaves of agricultural crops. The active ingredient belongs to the naturally derived chemical group of avermectine, causing paralysis of lepidoptera larvae due to the activation of chloride channel at nerves level. Affirm is acting mainly through ingestion, due to its mode of action and fast activity, it is effective at very low rates and on all instars stages. It has been developed for the use on pomefruits, stonefruits, grapes and a broda range of vegetables crops at a rate range of 1.5 to 3 g ai/100L. The product shows translaminar activity and rapid degradation on leaf surface; therefore the active ingredient breaks down in a very short time to sublethal doses for most beneficials organisms living on the vegetation. The short rentry time, generally 24 hours for beneficials and impollinators, makes Affirm compatible for IPM programme in orchards and greenhouses. Also the residue profile is very favourable, leading to a very low maximum residue level and short preharvest interval in all edible crops.
Assuntos
Inseticidas/farmacologia , Ivermectina/análogos & derivados , Lepidópteros/efeitos dos fármacos , Animais , Produtos Agrícolas , Frutas , Inseticidas/química , Ivermectina/química , Ivermectina/farmacologia , Larva/efeitos dos fármacos , Estrutura Molecular , Verduras , VitisRESUMO
The teaching process of auscultation is complex in itself, and difficult to operate since it requires a wide spectrum of patients with the most diverse cardiopulmonary pathologies, readily available during teaching and assessment hours, for an ever-growing number of medical students. In this paper we will focus on how virtual patient technologies can promote the evolution of the current teaching methodologies, promoting better learning. The chosen methodology was: a) a review of available medical simulation technologies for auscultation teaching; b) a case study illustrating how a virtual patient simulation technology has been successfully used to teach and certify auscultation skills. Results show the positive impact and high acceptability of virtual patient simulation technologies in the teaching of auscultation to medical students.
Assuntos
Simulação de Paciente , Estudantes de Medicina , Auscultação , Humanos , TecnologiaRESUMO
Monitoring of key physiological and pharmacological parameters is an important part of a closed loop control system in critical care. Optical fiber sensors provide a versatile platform technology that can be easily incorporated into existing in-dwelling catheters or face masks. With appropriate functional coatings they can be used to monitor a range of relevant parameters and two different examples are presented: (i) respiration monitoring; (ii) drug level monitoring. Respiration monitoring involves monitoring of temperature and humidity in inhaled and exhaled breath. The optical fiber sensor consists of a fiber Bragg grating to measure temperature and a tip coating whose refractive index changes with humidity. The sensor is demonstrated to be able to track breath to breath changes when incorporated into a mask. Drug level monitoring is demonstrated in vitro using a long period grating coated with molecularly imprinted polymer nanoparticles that are sensitive to fentanyl. The sensor has a limit of detection of 50ng/ml.
Assuntos
Cuidados Críticos , Fibras Ópticas , Refratometria , Tecnologia de Fibra Óptica , Humanos , UmidadeRESUMO
The purpose of the present article was to present the series operated by a Liver Transplant Group of the interior of the State of Sao Paulo, Brazil. Sixty patients were transplanted from May 2001 to May 2007. Thirty percent of the patients had alcoholic cirrhosis. 18.3% had C virus-induced cirrhosis, 10% had C virus- and alcohol-induced cirrhosis, 6% had B virus-induced cirrhosis, 13.3% had cryptogenic cirrhosis, 8.3% autoimmune cirrhosis, 13.3% had familial amyloidotic polyneuropathy (FAP), and 13.3% had hepatocellular carcinomas. The series was divided by a chronological criterion into two periods: A (n = 42) and B (n = 18) with the latter group operated based upon the Model for End-stage Liver Disease (MELD) criterion. Sixty-nine percent were men. Age ranged from 14 to 66 years. Period A included 12% Child A: 59.2%, Child B; 24%, Child C; and 4.8%, FAP. Period B comprises 22.2% Child A: 11.1%, Child B: 33.3%, Child C: and 33.3%, FAP. MELD scores ranged from 8 to 35 for period A and from 14 to 31 for period B. Intraoperative mortality was 2/42 patients for period A and 0/18 for period B, overall postoperative mortality was 40% including for period A, 35% among Child B and C patients, and 5% among FAP and Child A patients (P < .05) and 16.6% for period B among 11.1% Child B patients and 5.5% FAP patients; 3.3% of patients required retransplantation due to hepatic artery thrombosis. Real postoperative survival was 60% during period A and 83.3% during period B, with an overall survival rate of 67% for the two periods. The present results show levels of postoperative mortality, (especially during period B), and survival rates similar to those reported by several other centers in Brazil.
Assuntos
Transplante de Fígado/fisiologia , Adolescente , Adulto , Idoso , Brasil , Hepatite Viral Humana/cirurgia , Hospitais Universitários , Humanos , Cirrose Hepática/cirurgia , Hepatopatias/classificação , Hepatopatias/cirurgia , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
INTRODUCTION: The workflow in clinical flow cytometry laboratories must constantly be reviewed to develop technical procedures that improve quality and productivity and reduce costs. Using the Beckman Coulter dry coating technology, we customized a ten-color tube with dried antibody reagents, designated the Duraclone screening tube (DST), for screening hematological malignancies. Here, we compared the applicability, clinical and numerical equivalence, and cost and time required for the technical procedures between the liquid reagents and the DST. METHODS: The DST contains CD4 + Kappa-FITC, CD8 + Lambda-PE, CD3 + CD14-ECD, CD33-PE-Cy5.5, CD20 + CD56-PE-Cy7, CD34-APC, CD19-APC-AlexaFluor700, CD10-APC-AlexaFluor750, CD5-Pacific Blue, and CD45-Krome Orange. We evaluated 20 bone marrow samples, 13 peripheral blood samples, 6 lymph node biopsy samples, 5 fine-needle aspirate samples, 5 cerebrospinal fluid samples, and 1 pleural fluid sample. RESULTS: The DST was useful for more than 60% of our samples. It was able to enumerate the majority of the populations in all types of samples with a statistically acceptable correlation with the liquid reagents. The use of the DST translated into significant time and cost savings of 15.8% and 12.3%, respectively, compared with the use of the liquid reagent. The cost was reduced by $14.36 per sample. CONCLUSIONS: The DST is an efficient solution for screening hematological malignancies with improved quality, productivity, standardization, and sustainability. These improvements could benefit patients by providing faster diagnoses using a higher quality and lower cost reagent.
Assuntos
Neoplasias Hematológicas/diagnóstico , Anticorpos/imunologia , Humanos , Imunofenotipagem , Indicadores e Reagentes/economia , Indicadores e Reagentes/normas , Fatores de TempoRESUMO
BACKGROUND: Normal B lymphoid maturation occurs in bone marrow (BM) throughout life, but immature B-cell progenitors (BCPs) are more numerous in children than in adults. To assess the normal values according to age became important as BCPs are decreased in myelodysplastic syndromes and have been considered an important diagnostic and prognostic feature in these clonal disorders. METHODS: in a multicenter retrospective study from the Brazilian Group of Flow Cytometry we analyzed the variation of BCPs in normal BM according to age and technical peculiarities of each laboratory. We analysed of 45 BM donors and 89 cases examined for elucidation of transitory reactive cytopenias presenting a normal BM immunophenotyping. BCPs were enumerated as CD19+ /CD34+ /CD45dim /CD10+ cells (panel 1) or CD19+ /CD34+ /CD45dim cells (panel 2) among the total nucleated non-erythroid cells and as percentage of CD34+ cells. RESULTS: we included 134 cases. Panel 1 was applied in 88 cases and panel 2 was used in 46. Age range: 10 months to 89 years. In a multiple regression, % BCPs/total nucleated cells was an exponential function of age. Age explained alone 49.4% of the variance, while 'panel used' explained 1.8% and 'laboratory' explained 0.7%. Age explained only 24.9% of the variance of BCPs/CD34+ cells. CONCLUSIONS: in normal individuals, BM B-cell precursors varied mainly according to age, but were also dependent on technical peculiarities of operators and equipments. Analysis by phenotype and as percentage of total nucleated cells was more accurate and less susceptible to variation than evaluating % BCPs/total CD34+ cells. © 2017 International Clinical Cytometry Society.
Assuntos
Envelhecimento , Síndromes Mielodisplásicas/diagnóstico , Células Precursoras de Linfócitos B/citologia , Células Precursoras de Linfócitos B/patologia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/patologia , Brasil , Criança , Pré-Escolar , Citometria de Fluxo , Humanos , Lactente , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/patologia , Valores de Referência , Estudos Retrospectivos , Adulto JovemRESUMO
Auscultation is currently both a powerful screening tool, providing a cheap and quick initial assessment of a patient's clinical condition, and a hard skill to master. The teaching of auscultation in Universities is today reduced to an unsuitable number of hours. Virtual patient simulators can potentially mitigate this problem, by providing an interesting high-quality alternative to teaching with real patients or patient simulators. In this paper we evaluate the pedagogical impact of using a virtual patient simulation technology in a short workshop format for medical students, training them to detect cardiac pathologies. Results showed a significant improvement (+16%) in the differentiation between normal and pathological cases, although longer duration formats seem to be needed to accurately identify specific pathologies.
Assuntos
Auscultação/métodos , Simulação de Paciente , Tecnologia/educação , Tecnologia/métodos , Interface Usuário-Computador , Adolescente , Adulto , Idoso , Doenças Cardiovasculares/diagnóstico , Criança , Pré-Escolar , Competência Clínica , Simulação por Computador , Humanos , Pessoa de Meia-Idade , Projetos Piloto , Ensino , Adulto JovemRESUMO
Thiamethoxam, mainly sold under the trademark of Actara, is a neonicotinoid widely used in covered vegetables for the control of aphids and whiteflies. In these crops, and particularly in covered tomatoes, bumble-bees are used for cross-pollination as an alternative to labour intensive manual techniques. In this study, made on tomatoes grown in separated greenhouse plots in Murcia, Southern Spain, thiamethoxam was applied through drip irrigation at a rate of 200 g ai/ha, and as a split application of the same rate, to evaluate the effects on pollinating bumble bees compared to a foliar application of a toxic standard. The results showed that the toxic foliar standard had a clear effect on the pollination of tomato flowers, declining to zero pollination two weeks after application, whereas both the single and split drip irrigation applications of Actara had no effect on pollination when compared to the control plots. The count of dead adults and larvae did not show any differences between the treatments, whereas the measurement of sugar water consumption was shown to correlate well with pollination. The consumption of sugar water declined in the toxic standard plots by 69% with respect to the control, whilst the decline in lower dose drip irrigation application was only 3%. In regard to hive weight, and number of adults and brood after destructive sampling; there were no statistical differences between the treatments but a negative effect of the foliar treatment was observed. Based on these results we can conclude that a split application of Actara applied in drip irrigation to the soil/substrate has no effect on the bumble-bees used in tomatoes for pollination.
Assuntos
Agricultura/métodos , Abelhas/crescimento & desenvolvimento , Inseticidas/efeitos adversos , Nitrocompostos/efeitos adversos , Oxazinas/efeitos adversos , Solanum lycopersicum/parasitologia , Animais , Abelhas/efeitos dos fármacos , Abelhas/fisiologia , Relação Dose-Resposta a Droga , Solanum lycopersicum/crescimento & desenvolvimento , Neonicotinoides , Pólen/fisiologia , Segurança , Estações do Ano , Tiametoxam , TiazóisRESUMO
Asian men, who consume a low fat/high fibre soya-based diet, have very much lower incidence of prostate cancer than men from North America and Europe. The soya bean is a rich source of the isoflavonic phyto-oestrogens, daidzein, genistein and equol, compounds which may be cancer-protective in Asian populations. The lignans, enterolactone and enterodiol, plant oestrogens derived from cereals and vegetables, may act in a similar manner in vegetarian men. We report here on the measurement of isoflavonoids and lignans, by gas chromatography-mass spectrometry, in prostatic fluid of men from Asia and Europe and also on the metabolism of these compounds in Western men following dietary supplementation.
Assuntos
Glycine max/metabolismo , Isoflavonas/análise , Isoflavonas/metabolismo , Lignanas/análise , Lignanas/metabolismo , Óleo de Semente do Linho/metabolismo , Próstata/metabolismo , Adulto , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
The surface reactivity of glasses belonging to the (mol%) 31SiO2-11P2O5-(58-x)CaO-xMgO series, with x ranging from 0 to 32, was studied in Kokubo's simulated body fluid (SBF). Scanning electron microscopy, inductively coupled plasma spectroscopy and Fourier transform infrared spectroscopy were used to characterise the glass surface and the SBF compositional changes. All glasses develop surface layers rich in silica and calcium phosphate. An increasing surface activity with increasing MgO/CaO ratio was observed. In a previous investigation using magic-angle spinning nuclear magnetic resonance it was found that there is an increasing abundance of Q0 species in the glass structure with increasing MgO content. The present work shows that, when immersed in SBF, Q0-rich glasses are easily leached to form a silica gel layer. It is concluded that MgO in the glass indirectly improves the early stages of mineralisation by favouring Q0 speciation. This mechanism plays an important role in glass bioactivity.
Assuntos
Vidro , Silício/química , Técnicas In Vitro , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
A glass of nominal composition (wt%) 17.25 MgO-52.75 3CaO.P2O5-30 SiO2 and a glass-ceramic obtained from it showed surface modifications when immersed in an acellular medium having a composition similar to that of human blood plasma. A (Ca, P)-rich layer, with an approximate Ca/P atomic ratio of 1.7, identified as hydroxyapatite, developed on both samples. The precipitated film on the glassy sample was weakly bonded, whereas that formed on the glass-ceramic was strongly adherent. The apatite precipitated during the in vitro tests on both samples grew as a needle-like structure with crystals about 150-200 nm long and 50-70 nm thick, as measured on specimens soaked for 1 month in the simulated body fluid (SBF). The presence of calcium and phosphate ions in the SBF contributed to the precipitation of the (Ca, P)-rich layers on both specimens.
Assuntos
Materiais Biocompatíveis/química , Cerâmica/química , Vidro/química , Compostos de Fósforo , Sítios de Ligação , Sangue/metabolismo , Compostos de Cálcio/química , Técnicas In Vitro , Óxido de Magnésio/química , Microscopia Eletrônica de Varredura , Modelos Químicos , Óxidos/química , Fósforo/química , Dióxido de Silício/química , Propriedades de SuperfícieRESUMO
The substitution of tris/HCl buffer by CO(2)/HCO(3)(-) buffer in inorganic plasma was studied. An appropriate gas mixture of CO(2)/N(2) was continuously bubbled in Kokubo's SBF solution prepared without addition of Tris/HCl. This method enables buffering the solution within the 7.3-7.4 pH interval and, at the same time, reaching a HCO(3)(-) concentration between 24 and 27 mmol dm(-3), which are the normal concentrations reported for blood plasma. Mineralisation studies on calcium phosphate ceramics using this solution showed that, in the presence of such hydrogencarbonate concentrations, the formation of a mineralisation layer on the ceramic occurs via a carbonated octacalcium phosphate, that evolves to carbonated hydroxyapatite. The results suggest that mineralisation studies in this new carbonate-containing simulated inorganic plasma mimic biomineralisation more closely than traditional SBF.
Assuntos
Bicarbonatos/química , Substitutos Sanguíneos/química , Dióxido de Carbono/química , Soluções Tampão , Cerâmica , Cinética , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de SuperfícieRESUMO
A non-bioactive glass-ceramic (GC13) that contains hydroxyapatite (Ca5(PO4)3OH), diopside (CaMg(SiO3)2) and althausite (Mg2 PO4OH) as crystalline phases has been obtained by thermal treatment of a parent bioactive glass (G13) of nominal composition (wt%) 40.0 CaO-34.5 SiO2-16.5 P2O5-8.5 MgO-0.5CaF2. To induce bioactivity, GC13 was chemically treated with 1 M HCl for different periods of time. After chemical etching the in vitro studies showed formation of an apatite-like surface layer. In this article the influence of etching time both on the surface composition of the glass-ceramic and on the growth rate of the apatite layer is studied. It is concluded that the presence of hydroxyapatite in the glass-ceramic, associated to microstructural fluctuations, can favour apatite deposition in vitro.
Assuntos
Apatitas/análise , Materiais Biocompatíveis/química , Cerâmica/química , Durapatita/química , Ácido Clorídrico/farmacologia , Materiais Biocompatíveis/farmacologia , Cálcio/análise , Cerâmica/farmacologia , Cristalização , Durapatita/farmacologia , Magnésio/análise , Teste de Materiais , Microscopia Eletrônica de Varredura , Fósforo/análise , Silício/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
The role of albumin in the mineralisation process of commercial hydroxyapatite (HAp) and synthesised biphasic (HAp-tricalcium phosphate) ceramics in a bufferless simulated inorganic plasma (HBSS) was investigated by conventional in vitro tests and static and dynamic wettability measurements. Albumin was either pre-adsorbed or solubilised in HBSS. It was found that calcium complexation by albumin plays a key role in early mineralisation kinetics, so that mineralisation is favoured when albumin is pre-adsorbed and hindered when it is dissolved in HBSS. In the biphasic ceramic this picture is complicated by the fact that albumin, in solution, seems to promote the dissolution of tricalcium phosphate, and simultaneously compete for calcium with the ceramic. It also appears that albumin has a stabilising effect of octacalcium phosphate present in deposits on commercial HAp. The same effect may be present in the case of the biphasic ceramic, at earlier mineralisation times, when octacalcium phosphate appears as a precursor of HAp. Octacalcium phosphate formation on commercial apatite is accompanied by carbonate substitution in phosphate positions.
Assuntos
Albuminas/química , Materiais Biocompatíveis/química , Cerâmica/química , Meios de Cultura/química , Meios de Cultura/metabolismo , Fosfatos/química , Albuminas/fisiologia , Fosfatos de Cálcio/química , Precipitação Química , Durapatita/química , Concentração de Íons de Hidrogênio , Cinética , Teste de Materiais , Microscopia Eletrônica de Varredura , Modelos Químicos , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de TempoRESUMO
Glasses and glass ceramics of fluorapatite-anorthite (eutectic composition) were produced and characterized in order to evaluate their potential application in biomedicine. Bio-reactivity was determined by in vitro tests by immersion of powders in simulated plasma liquids as well as by in vivo experiments by implantation in rabbits. According to the results, the investigated materials are bio-acceptable since no toxic or other harmful evidence was detected. Glass-ceramics showed remarkable inertness, whereas glasses spontaneously dissolved in SBF and after 1 week moderate formation of apatite was observed, that however ceased within a month.
Assuntos
Silicatos de Alumínio , Silicatos de Alumínio/química , Apatitas/química , Materiais Biocompatíveis/química , Cerâmica/química , Vidro , Silicatos de Alumínio/metabolismo , Animais , Apatitas/metabolismo , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , CoelhosRESUMO
A glass of nominal composition (wt%) 40.0 CaO-34.5 SiO2-16.5 P2O5-8.5 MgO-0.5 CaF2 has been obtained (G13). The glass showed in vitro bioactivity evidenced by the formation on its surface of a calcium phosphate-rich layer when soaked in a solution with ionic composition analogous to human plasma. By thermal treatments of G13, a glass-ceramic (GC13) containing apatite, diopside, althausite and akermanite as crystalline phases was developed. GC13 as-made did not show in vitro bioactivity. However, after chemical treatment of GC13 with 1 M HCl (GC13-HCl), the in vitro studies showed the formation of an apatite-like layer covering certain areas of the material surface. The influence of both chemical and morphological factors on the in vitro bioactivity has been studied.