Browsing by Author "Ferreira, Teresa"
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- Citric acid as a safe alternative to oxalic acid in the Gomori reticulin technique: a comparative studyPublication . Bento, Ana; Nascimento, Ana; Nobre, Sofia; Ferreira, Teresa; Borges-Ferro, Amadeu; Marques-Ramos, AnaThe use of oxalic acid is common in metallic impregnation techniques, where it serves as a reducing and bleaching agent for potassium permanganate. Given that oxalic acid is harmful to health, its replacement with another reagent is advantageous for healthcare professionals handling it in laboratory settings. Considering that citric acid can also reduce potassium permanganate, this study aimed to determine whether oxalic acid in the Gomori reticulin technique could be replaced by citric acid, a compound substantially less hazardous to health. To this end, 1%, 5%, and 10% citric acid solutions were tested on porcine liver and kidney samples, and the intensity of reticulin fiber staining, contrast, and overall morphological preservation were assessed in comparison with 1% oxalic acid. The results showed no statistically significant differences between the positive control (oxalic acid) and the citric acid protocols, with the 5% citric acid concentration proving most favorable in terms of required incubation time and the evaluated morphological parameters. It was therefore concluded that citric acid can be used as a bleaching agent for potassium permanganate in the Gomori technique, effectively replacing oxalic acid.
- Efeito da duração da impregnação em parafina do material histológico na marcação imunohistoquímicaPublication . Alexandre, Paulo; Castanheira, Lara; Ferreira, Teresa; Ferro, Amadeu BorgesA impregnação é uma importante etapa da técnica histológica que consiste em embeber o material histológico previamente fixado, desidratado e diafanizado no meio de inclusão (e.g. parafina). Sabendo que é importante analisar os efeitos da exposição dos tecidos a temperaturas superiores a 60ºC por longos períodos de tempo, de modo a evitar danos nos antigénios, tomou-se, como objetivo deste trabalho, estudar os efeitos da duração da impregnação na técnica imunohistoquímica (IHQ). Selecionaram-se 10 amostras de apêndice íleo-cecal humano fixadas em Formol a 10% Neutro Tamponado das quais se recolheram 30 fragmentos que foram submetidos a processamento histológico com recurso a parafina a 64ºC, com durações de 30, 60 e 300 minutos no processador Tissue-Tek® Xpress® 120x. A IHQ foi efetuada pelo método de polímero indireto recorrendo aos soros primários anti: CD79α; Citoqueratinas (clone MNF116); proteína S100 e Ki-67. Os resultados foram observados microscopicamente e classificados numa escala 0-100, segundo os parâmetros preservação morfológica celular, quantidade de estruturas marcadas, intensidade de marcação, fundo e marcação inespecífica. No tratamento estatístico recorreu-se ao teste não paramétrico de Kruskal-Wallis (alfa=0,05). Os casos submetidos a 30 minutos de impregnação obtiveram classificações que se caracterizam por um par média/desvio padrão de 89,58/10,45, enquanto os de 60 minutos obtiveram 90,57/9,85 e os de 300 minutos obtiveram 89,94/10,84. O teste de Kruskal-Wallis demonstrou que não existe qualquer evidência estatística de diferenças entre as durações estudadas. Este resultado contraria o publicado por outros autores que encontraram diferenças após 1 e 8 horas de impregnação. No entanto, estes autores não recorreram a recuperação antigénica otimizada na técnica de IHQ, o que pode ter condicionado os resultados obtidos. Conclui-se que, para os anticorpos analisados, não existem diferenças na qualidade da imunomarcação consoante a duração da impregnação, de 30 minutos até 5 horas.
- Trends on Aspergillus epidemiology: perspectives from a national reference laboratory surveillance programPublication . Sabino, Raquel; Gonçalves, Paulo; Martins-Melo, Aryse; Simões, Daniela; Oliveira, Mariana; Francisco, Mariana; Viegas, Carla; Carvalho, Dinah; Martins, Carlos; Ferreira, Teresa; Toscano, Cristina; Simões, Helena; Veríssimo, CristinaIdentification of Aspergillus to species level is important since sibling species may display variable susceptibilities to multiple antifungal drugs and also because correct identification contributes to improving the knowledge of epidemiological studies. Two retrospective laboratory studies were conducted on Aspergillus surveillance at the Portuguese National Mycology Reference Laboratory. The first, covering the period 2017–2018, aimed to study the molecular epidemiology of 256 Aspergillus isolates obtained from patients with respiratory, subcutaneous, or systemic infections and from environmental samples. The second, using our entire collection of clinical and environmental A. fumigatus isolates (N = 337), collected between 2012 and 2019, aimed to determine the frequency of azole-resistant A. fumigatus isolates. Aspergillus fumigatus sensu stricto was the most frequent species in both clinical and environmental samples. Overall, and considering all Aspergillus sections identified, a high frequency of cryptic species was detected, based on beta-tubulin or calmodulin sequencing (37% in clinical and 51% in environmental isolates). Regarding all Fumigati isolates recovered from 2012–2019, the frequency of cryptic species was 5.3% (18/337), with the identification of A. felis (complex), A. lentulus, A. udagawae, A. hiratsukae, and A. oerlinghauensis. To determine the frequency of azole resistance of A. fumigatus, isolates were screened for azole resistance using azole-agars, and 53 possible resistant isolates were tested by the CLSI microdilution reference method. Nine A. fumigatus sensu stricto and six Fumigati cryptic isolates showed high minimal inhibitory concentrations to itraconazole, voriconazole, and/or posaconazole. Real-time PCR to detect cyp51A mutations and sequencing of the cyp51A gene and its promoter were performed. The overall frequency of resistance to azoles in A. fumigatus sensu stricto was 3.0%. With this retrospective analysis, we were able to detect one azole-resistant G54R mutant A. fumigatus environmental isolate, collected in 2015. The TR34/L98H mutation, linked to the environmental transmission route of azole resistance, was the most frequently detected mutation (N = 4; 1.4%). Our findings underline the demand for correct identification and susceptibility testing of Aspergillus isolates.