RESUMEN
Biomimetics constitutes an attractive strategy for the development of new functional materials in a variety of fields. Nacre is a natural composite composed of 95% aragonite and 5% organic materials with a layered and hierarchical structure which has be shown to have high toughness and mechanical strength and resistance. As such, mimicking nacre's composition and structure can be the key for the development of new materials with increased mechanical properties and stability. This review focuses on recent developments achieved in the production of nacre-like nanocomposites using the layer-by-layer deposition technique. This technique was chosen due to its ability to create nanostructured layered structures with thickness controlled at the nanoscale level using a wide range of different materials. Several examples of nacre-inspired designs of multilayer nanocomposites are overviewed, and their possible applications are discussed, in particular in the biomedical field.
Asunto(s)
Nanocompuestos , Materiales Biomiméticos , Biomimética , Carbonato de Calcio , NácarRESUMEN
Autologous fat graft to the breast is a useful tool to correct defects after breast conservative treatment (BCT). Although this procedure gains popularity, little is known about the interaction between the fat graft and the prior oncological environment. Evidences of safety of this procedure in healthy breast and after post-mastectomy reconstruction exist. However, there is paucity of data among patients who underwent BCT which are hypothetically under a higher risk of local recurrence (LR). Fifty-nine patients, with prior BCT, underwent 75 autologous fat graft procedures using the Coleman's technique, between October 2005 and July 2008. Follow-up was made by clinical and radiologic examination at least once, after 6 months of the procedure. Mean age was 50 ± 8.5 years, and mean follow-up was 34.4 ± 15.3 months. Mean time from oncological surgery to the first fat grafting procedure was 76.6 ± 30.9 months. Most of patients were at initial stage 0 (11.8%), I (33.8%), or IIA (23.7%). Immediate complication was observed in three cases (4%). Only three cases of true LR (4%) associated with the procedure were observed during the follow-up. Abnormal breast images were present in 20% of the postoperative mammograms, and in 8% of the cases, biopsy was warranted. Autologous fat graft is a safe procedure to correct breast defects after BCT, with low postoperative complications. Although it was not associated with increased risk of LR in the group of patients studied, prospective trials are needed to certify that it does not interfere in patient's oncological prognosis.
Asunto(s)
Tejido Adiposo/trasplante , Neoplasias de la Mama/cirugía , Trasplante Autólogo/métodos , Adulto , Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/patología , Femenino , Estudios de Seguimiento , Humanos , Mamoplastia/métodos , Mastectomía Segmentaria , Persona de Mediana Edad , Recurrencia Local de Neoplasia/patología , Estudios Prospectivos , Trasplante Autólogo/efectos adversos , Resultado del TratamientoRESUMEN
OBJECTIVES: Besides possessing good mechanical properties, dental materials should present a good biological behavior and should not injure the involved tissues. Bond strength and biocompatibility are both highly significant properties of dentin adhesives. For that matter, these properties of four generations of adhesive systems (Multi-Purpose/Single Bond/SE Plus/Easy Bond) were evaluated. MATERIALS AND METHODS: Eighty bovine teeth had their dentin exposed (500- and 200-µm thickness). Adhesive was applied on the dentin layer of each specimen. Following that, the microshearing test was performed for all samples. A dentin barrier test was used for the cytotoxicity evaluation. Cell cultures (SV3NeoB) were collected from testing materials by means of 200- or 500-µm-thick dentin slices and placed in a cell culture perfusion chamber. Cell viability was measured 24 h post-exposition by means of a photometrical test (MTT test). RESULTS: The best bonding performance was shown by the single-step adhesive Easy Bond (21 MPa, 200 µm; 27 MPa, 500 µm) followed by Single Bond (15.6 MPa, 200 µm; 23.4 MPa, 500 µm), SE Plus (18.2 MPa, 200 µm; 20 MPa, 500 µm), and Multi-Purpose (15.2 MPa, 200 µm; 17.9 MPa, 500 µm). Regarding the cytotoxicity, Multi-Purpose slightly reduced the cell viability to 92% (200 µm)/93% (500 µm). Single Bond was reasonably cytotoxic, reducing cell viability to 71% (200 µm)/64% (500 µm). The self-etching adhesive Scotchbond SE decreased cell viability to 85% (200 µm)/71% (500 µm). Conversely, Easy Bond did not reduce cell viability in this test, regardless of the dentin thickness. CONCLUSIONS: Results showed that the one-step system had the best bond strength performance and was the least toxic to pulp cells. In multiple-step systems, a correct bonding technique must be done, and a pulp capping strategy is necessary for achieving good performance in both properties. CLINICAL RELEVANCE: The study showed a promising system (one-step self-etching), referring to it as a good alternative for specific cases, mainly due to its technical simplicity and good biological responses.
Asunto(s)
Adhesivos , Materiales Biocompatibles , Dentina , Animales , Bovinos , IncisivoRESUMEN
A prevalência de oocistos de Cryptosporidium parvum foi determinada em amostras fecais de 25 sidéticos de ambos os sexos com gastroenterite, durante o período de abril a maio de 2002 no Centro de Saúde Vila dos Comerciários em Porto Alegre, RS. Os oocistos foram detectados pela coloraçäo da safranina modificada a quente. Pelos dados observados das 25 amostras estudadas, 16 porcento (4) apresentaram resultados positivos e 84 porcento (21) foram negativas para a pesquisa de oocistos. No que se refere à ocorrência de oocistos de C. parvum, em relaçäo ao sexo, foi verificado que os maiores percentuais de infecçäo foram obtidos entre as pacientes do sexo feminino 12 porcento (3), enquanto que entre os sidéticos do sexo masculino o índice de infecçäo foi igual a 4 porcento (1).
Asunto(s)
Humanos , Masculino , Femenino , Cryptosporidium parvum , Heces , Infecciones por Protozoos/diagnóstico , Oocitos , Síndrome de Inmunodeficiencia Adquirida/complicaciones , Gastroenteritis , PrevalenciaRESUMEN
Em estudo multicêntrico em larga escal, aberto, näo comparativo, foram avaliadas 3.629 pacientes portadoras de dismenorréia primária, virgens de tratamento ou com resposta insatisfatória a analgésicos convencionais. O piroxicam foi adminsitrado durante dois ciclos menstruais consecutivos, na posologia de 40 mg (duas cápsulas), em dose única diária nos dois primeiros dias do fluxo menstrual ou no início da dor, e de 20 mg (uma cápsula) nos 3-, 4- e 5- dias, se necessário. A evoluçäo da intensidade da dor mostrou que 3.418 (94%) pacientes apresentaram dor severa ou moderada no ciclo inicial (pré-tratamento) e no 2- dia do último ciclo de tratamento, 3455 (95%) pacientes referiram dor leve ou ausente (p < 0,001). O absenteísmo foi relatado em 2.119 (58%) pacientes no pré-tratamento, e ao término do estudo (2- ciclo) apenas 97 (3%) pacientes apresentavam-se incapacitadas de realizar suas atividades diárias. No final do tratamento 3.586 (99%) pacientes referiram estar assintomáticas ou melhores em relaçäo ao início do mesmo. Segundo a avaliaçäo global do investigador, os resultados foram considerados excelentes ou bons em 3.327 (92%) pacientes. Apenas duas pacientes tiveram que interromper a medicaçäo devido a reaçöes adversas significativas. O autor conclui que, nesta avaliaçäo multicêntrica realizada em todo o país, o piroxicam foi bastante eficaz e bem tolerado no tratamento da dismenorréia primária
Asunto(s)
Adolescente , Adulto , Persona de Mediana Edad , Humanos , Femenino , Dismenorrea/tratamiento farmacológico , Piroxicam/uso terapéutico , Ensayos Clínicos como AsuntoRESUMEN
Em estudo multicêntrico, aberto, näo comparativo, foi avaliada a tolerabilidade e eficácia do piroxicam administrado a 152 pacientes com idade de 12 a 16 anos, portadoras de dismenorréia primária incapacitante há pelo menos quatro meses. O piroxicam foi administrado na posologia de 40 mg (duas cápsulas), em dose única diária, nos dois primeiros dias logo após o início da dor e 20 mg (uma cápsula) do 3§ ao 5§ dia, por dois ciclos consecutivos. Das 152 pacientes que iniciaram o estudo, 140 puderam ser avaliadas no 1§ ciclo e 136 no 2§; as pacientes excluídas da análise da eficácia o foram devido ao fato de näo preencherem os critérios de inclusäo. Ao término do 1§ dia de tratamento do 1§ ciclo, a intensidade da dor foi considerada ausente em 20% das pacientes e inferior ao habitual em 33%; já no segundo dia, 60% e 34% respectivamente, apresentaram este padräo de resposta terapêutica. Durante o 2§ ciclo de tratamento um alívio semelhante da dor foi observado. Houve uma reduçäo significativa (p <0,001) no número de dias de absenteísmo das pacientes, a partir do 1§ ciclo. A avaliaçäo clínica global mostrou no 1§ e 2§ ciclo resultados excelentes/bons em 95% e 96%, respectivamente. Piroxicam foi bem tolerado, pois apenas 9 (5,9%) pacientes relataram reaçöes adversas sendo as mesmas de intensidade leve ou moderada; 2 (1,3%) pacientes descontinuaram o tratamento devido a reaçöes adversas. A avaliaçäo global da tolerabilidade evidenciou resultados excelentes/bons em 97% das pacientes no 1§ ciclo e 99% no 2§ ciclo de tratamento. Conclue-se que nesta populaçäo de pacientes portadoras de dismenorréia primária e com idade variando de 12 a 16 anos, o piroxicam foi eficaz e bem tolerado