Browsing by Author "Branco, Patrícia"
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- Cell-to-cell contact and antimicrobial peptides play a combined role in the death of Lachanchea thermotolerans during mixed-culture alcoholic fermentation with Saccharomyces cerevisiaePublication . Kemsawasd, Varongsiri; Branco, Patrícia; Almeida, Maria Gabriela; Caldeira, Jorge; Albergaria, Helena Albergaria; Arneborg, NilsThe roles of cell-to-cell contact and antimicrobial peptides in the early death of Lachanchea thermotolerans CBS2803 during anaerobic, mixed-culture fermentations with Saccharomyces cerevisiae S101 were investigated using a commercially available, double-compartment fermentation system separated by cellulose membranes with different pore sizes, i.e. 1000 kDa for mixed- and single-culture fermentations, and 1000 and 3.5-5 kDa for compartmentalized-culture fermentations. SDS-PAGE and gel filtration chromatography were used to determine an antimicrobial peptidic fraction in the fermentations. Our results showed comparable amounts of the antimicrobial peptidic fraction in the inner compartments of the mixed-culture and 1000 kDa compartmentalized-culture fermentations containing L. thermotolerans after 4 days of fermentation, but a lower death rate of L. thermotolerans in the 1000 kDa compartmentalized-culture fermentation than in the mixed-culture fermentation. Furthermore, L. thermotolerans died off even more slowly in the 3.5-5 kDa than in the 1000 kDa compartmentalized-culture fermentation, which coincided with the presence of less of the antimicrobial peptidic fraction in the inner compartment of that fermentation than of the 1000 kDa compartmentalized-culture fermentation. Taken together, these results indicate that the death of L. thermotolerans in mixed cultures with S. cerevisiae is caused by a combination of cell-to-cell contact and antimicrobial peptides.
- Dimensional stability of two impression materials after a 6-month storage periodPublication . Martins, Francisco; Branco, Patrícia; Reis, José; Barbero Navarro, Ignacio; Maurício, Paulo
- Fungal peritonitis in peritoneal dialysis patients: is previous antibiotic therapy an essential condition?Publication . Guimarães Rosa, Nuno; Silva, Sónia; Lopes, José António; Branco, Patrícia; de Almeida, Edgar; Ribeiro, Carlos; Abreu, Fernando; Barbas, José; Martins Prata, M.The aim of this study was to analyse the clinical and microbiological features of fungal peritonitis, in chronic peritoneal dialysis patients, focusing on non-traditional risk factors for this feared complication. From 2001 to 2004, five episodes of fungal peritonitis were diagnosed in five different patients, accounting for 4.5% of all peritonitis cases seen during this period. Candida spp. were the most frequent isolates. In all cases, peritoneal dialysis catheter removal and switching to haemodialysis were necessary. In these five cases of fungal peritonitis only one was preceded by antibiotic use, within the previous 3 months, the classical risk factor for fungal peritonitis. Identifying predisposing factors usually not taken into account, may lead to an early diagnosis and to a better understanding of fungal peritonitis pathogenesis.
- Homozygous C677T mutation of the 5,10-methylenetetrahydrofolate reductase gene with hyperhomocysteinaemia associated with lupus anticoagulant in a chronic peritoneal dialysis patient with cerebral venous thrombosis- Case ReportPublication . Guimaraes, Nuno; Silva, Sónia; Branco, Patrícia; Almeida, Edgar de; Canhão, Patrícia; Barbas, José; Gomes da Costa, A.; Prata, M. MartinsWe report a case of a cerebral venous thrombosis (CVT) in a chronic kidney disease patient with three CVT predisposing conditions. A 53 year-old woman on chronic peritoneal dialysis presented to the emergency department with acute headache and vertigo. The neurological examination and head CT scan performed at the emergency department were normal but, three days later, a lateral gait deviation and a horizontal nystagmus were identified. A brain MRI and MRI-venogram confirmed a left lateral sinus thrombosis. Hormonal replacement therapy (HRT), a positive lupus anticoagulante and a homozygous mutation on the methylenetetrahydrofolate reductase gene, with hyperhomocysteinaemia, were the three well-known prothrombotic conditions identified in this patient. HRT was discontinued, the patient started anticoagulation with warfarin and folic acid supplementation and was discharged, 10 days after admission, complaining of a mild vertigo. After six months of therapy the patient had vertigo improvement and maintained a positive lupus anticoagulant. The head MRI and MRI-venography showed a thrombus reduction.
- Identification of novel GAPDH-derived antimicrobial peptides secreted by Saccharomyces cerevisiae and involved in wine microbial interactionsPublication . Branco, Patrícia; Francisco, Diana; Chambon, Christophe; Hébraud, Michel; Arneborg, Nils; Almeida, Maria Gabriela; Caldeira, Jorge; Albergaria, HelenaSaccharomyces cerevisiae plays a primordial role in alcoholic fermentation and has a vast worldwide application in the production of fuel-ethanol, food and beverages. The dominance of S. cerevisiae over other microbial species during alcoholic fermentations has been traditionally ascribed to its higher ethanol tolerance. However, recent studies suggested that other phenomena, such as microbial interactions mediated by killer-like toxins, might play an important role. Here we show that S. cerevisiae secretes antimicrobial peptides (AMPs) during alcoholic fermentation that are active against a wide variety of wine-related yeasts (e.g. Dekkera bruxellensis) and bacteria (e.g. Oenococcus oeni). Mass spectrometry analyses revealed that these AMPs correspond to fragments of the S. cerevisiae glyceraldehyde 3-phosphate dehydrogenase (GAPDH) protein. The involvement of GAPDH-derived peptides in wine microbial interactions was further sustained by results obtained in mixed cultures performed with S. cerevisiae single mutants deleted in each of the GAPDH codifying genes (TDH1-3) and also with a S. cerevisiae mutant deleted in the YCA1 gene, which codifies the apoptosis-involved enzyme metacaspase. These findings are discussed in the context of wine microbial interactions, biopreservation potential and the role of GAPDH in the defence system of S. cerevisiae.