The objectives of the present study were to evaluate (1) the capacity of the microalga Prototheca zopfii isolated from subclinical bovine mastitis cases to form biofilms; and (2) the resistance of these isolates to sanitizing agents. Ten isolates of P. zopfii from cows with subclinical mastitis (somatic cell count>200×10(3) cells/mL), distributed in 5 dairy farms, were evaluated for their capacity to form biofilms in polystyrene microplate assays and stainless steel coupons, at 25°C and 37°C±1°C. Prototheca zopfii were isolated from milk samples via microbiological culture and analyzed by 18S rRNA gene sequencing. Biofilm formation on the coupons was observed by scanning electron microscopy. The resistance to sanitizing agents was assessed using the biofilm-forming P. zopfii isolates in stainless steel coupon assays, which were subjected to 3 sanitizers: peracetic acid, sodium hypochlorite, and iodine solution. To evaluate resistance to the sanitizers, the minimum inhibitory concentration (MIC) technique was performed using decreasing concentrations of the sanitizing agents (20, 10, 5, 2.5, 1.25, 0.625, 0.312, 0.156, 0.078, 0.039, and 0.019 g/L). After inoculating the isolates, all concentrations were evaluated at 3 distinct incubation periods (24, 48, and 72 h) to assess the effect of incubation time on the MIC. Using the polystyrene microplate assays, 1 isolate showed weak biofilm production, 5 moderate, and 4 strong, when incubated at 25°C±1. For isolates incubated at 37°C±1, 6 showed weak biofilm production and 4 moderate. All P. zopfii isolates (n=10) had the capacity to form biofilms on stainless steel coupons. The longer the incubation period of the P. zopfii isolates at different dilutions, the greater the concentrations of sanitizer needed to prevent growth of the microalgae under the tested conditions. We detected a significant effect of sanitizer and time of incubation (24, 48, and 72 h) on MIC values against P. zopfii isolates. The isolates were sensitive in vitro to peracetic acid (MIC90≥0.019 g/L), sodium hypochlorite (MIC90≥0.312 g/L), and iodine solution (MIC90≥0.625 g/L), after 24 h of incubation (where MIC90=concentration needed to inhibit 90% of isolates). Of the tested sanitizers, peracetic acid had the greatest efficiency against P. zopfii. We conclude that P. zopfii isolates are capable of biofilm production, which may contribute to their persistence in a milking and dairy environment.
Purpose: To measure the microgap between dental implants and custom abutments fabricated using different computer-aided design/computer-aided manufacture (CAD/CAM) methods before and after mechanical cycling. Materials and Methods: CAD software (Dental System, 3Shape) was used to design a custom abutment for a single-unit, screw-retained crown compatible with a 4.1-mm external hexagon dental implant. The resulting stereolithography file was sent for manufacturing using four CAD/CAM methods (n = 40): milling and sintering of zirconium dioxide (ZO group), cobalt-chromium (Co-Cr) sintered via selective laser melting (SLM group), fully sintered machined Co-Cr alloy (MM group), and machined and sintered agglutinated Co-Cr alloy powder (AM group). Prefabricated titanium abutments (TI group) were used as controls. Each abutment was placed on a dental implant measuring 4.1 × 11 mm (SA411, SIN) inserted into an aluminum block. Measurements were taken using scanning electron microscopy (SEM) (×4,000) on four regions of the implant-abutment interface (IAI) and at a relative distance of 90 degrees from each other. The specimens were mechanically aged (1 million cycles, 2 Hz, 100 N, 37°C) and the IAI width was measured again using the same approach. Data were analyzed using two-way analysis of variance, followed by the Tukey test. Results: After mechanical cycling, the best adaptation results were obtained from the TI (2.29 ± 1.13 µm), AM (3.58 ± 1.80 µm), and MM (1.89 ± 0.98 µm) groups. A significantly worse adaptation outcome was observed for the SLM (18.40 ± 20.78 µm) and ZO (10.42 ± 0.80 µm) groups. Mechanical cycling had a marked effect only on the AM specimens, which significantly increased the microgap at the IAI. Conclusion: Custom abutments fabricated using fully sintered machined Co-Cr alloy and machined and sintered agglutinated Co-Cr alloy powder demonstrated the best adaptation results at the IAI, similar to those obtained with commercial prefabricated titanium abutments after mechanical cycling. The adaptation of custom abutments made by means of SLM or milling and sintering of zirconium dioxide were worse both before and after mechanical cycling.
A Deus pelo dom da vida e por todas as oportunidades e proteção.Aos meus pais Fernando e Silvia por todas as batalhas, dedicação em minha criação, apoio em todas as fases da minha vida e amor dedicado. Por serem meus exemplos. Amo vocês para sempre.Ao meu namorado Roberto, pelo apoio e suporte nestes anos longe. Pelas sábias palavras e por ser um exemplo de pessoa e profissional. Você é o amor da minha vida! Ao meu irmão Daniel e minha avó Odette por sempre estarem presentes nos principais momentos da minha vida.A minha avó Wilma (in memorian) por ter proporcionado uma infância tão feliz e com tantas lembranças em sua casa.Aos meus bichinhos, Toy (in memoriam), por ser a principal razão na escolha da minha profissão, saudades imensas e eternas. Chico, pelas despedidas tristes e recepções calorosas nas minhas viagens semanais para Pirassununga. Lola e Milk, presentes que Pira me deu. Amo vocês! A minha amiga Mariane pela amizade e carinho por todos estes anos, companheira de tantas aventuras, de momentos difíceis e muitas risadas, mas principalmente por me transformar em uma Silva! Amo muito você! A toda a família da Mari, Tia Sandra (Sandrinha), Tio Roberto (Betão), Vó Mércia, Aline, Du, Rômulo, Bia, Yuri, Luna e Naila (in memorian), por sempre me receberem de braços abertos "nas casas" de vocês, como membro da família e cuidarem de mim. Amo vocês! A Universidade de São Paulo e a Faculdade de Zootecnia e Engenharia de Alimentos pela oportunidade de realização do Mestrado.A minha orientadora Mônica Roberta Mazalli por me aceitar como sua primeira aluna de mestrado, pela dedicação intensa e pelas palavras de amizade e carinho. Você é uma querida! Muito obrigada! Ao José Roberto Medina, marido da professora Mônica, pela ajuda com seu vasto conhecimento em nutrição animal e pelos finais de semana perdidos misturando as rações. Meus mais sinceros agradecimentos.A Professora Angélica Simone Cravo Pereira, por me abrir as portas da USP e me colocar em ótimas mãos. Obrigada também pelo meu maior presente: a Lola! Ao Professor Flávio Vieira Meirelles pela colaboração no projeto com seu conhecimento e por disponibilizar seus equipamentos e laboratório.A família de Pirassununga: Lucinéia, Simi e Professor Márcio, muito obrigada pelos momentos descontraídos e alegres com vocês.A minha amiga Nara pela companhia e risadas de muitas noites, pelas comidinhas maravilhosas e especiais sempre que tinha vontade e por cuidar de mim durante viroses e crises renais! Muitas saudades, te amo! Ao Rodrigo Barreto por toda a ajuda e por transferir seus conhecimentos com tanto bom humor. Por atender as minhas dúvidas a todos os momentos e lugares. Você se tornou um amigo querido e eu te desejo tudo de melhor e ainda mais sucesso! A Rafaella Maniriques, aluna de iniciação científica, pela contribuição neste trabalho. O experimento foi realizado no Biotério Experimental da USP em Pirassununga -SP. Na primeira fase foram utilizados 42 coelhos machos em crescimento da raça Nova Zelândia mantidos individualmente durante todo o experimento. O ens...
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