Browsing by Author "Barreto, Celeste"
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- Cystic Fibrosis Newborn Screening in Portugal: PAP Value in Populations with Stringent Rules for Genetic StudiesPublication . Marcão, Ana; Barreto, Celeste; Pereira, Luísa; Vaz, Luísa; Cavaco, José; Casimiro, Ana; Félix, Miguel; Silva, Teresa; Barbosa, Telma; Freitas, Cristina; Nunes, Sidónia; Felício, Verónica; Lopes, Lurdes; Amaral, Margarida; Vilarinho, LauraNewborn screening (NBS) for cystic fibrosis (CF) has been shown to be advantageous for children with CF, and has thus been included in most NBS programs using various algorithms. With this study, we intend to establish the most appropriate algorithm for CF-NBS in the Portuguese population, to determine the incidence, and to contribute to elucidating the genetic epidemiology of CF in Portugal. This was a nationwide three-year pilot study including 255,000 newborns (NB) that were also screened for congenital hypothyroidism (CH) and 24 other metabolic disorders included in the Portuguese screening program. Most samples were collected in local health centers spread all over the country, between the 3rd and 6th days of life. The algorithm tested includes immunoreactive trypsinogen (IRT) determination, pancreatitis associated protein (PAP) as a second tier, and genetic study for cases referred to specialized clinical centers. Thirty-four CF cases were confirmed positive, thus indicating an incidence of 1:7500 NB. The p.F508del mutation was found in 79% of the alleles. According to the results presented here, CF-NBS is recommended to be included in the Portuguese NBS panel with a small adjustment regarding the PAP cut-off, which we expect to contribute to the improvement of the CF-NBS performance. According to our results, this algorithm is a valuable alternative for CF-NBS in populations with stringent rules for genetic studies.
- HGF Stimulation of Rac1 Signaling Enhances Pharmacological Correction of the Most Prevalent Cystic Fibrosis Mutant F508del-CFTRPublication . Moniz, Sónia; Sousa, Marisa; Moraes, Bruno José; Mendes, Ana Isabel; Palma, Marta; Barreto, Celeste; Fragata, José I.; Amaral, Margarida D; Matos, PauloCystic fibrosis (CF), a major life-limiting genetic disease leading to severe respiratory symptoms, is caused by mutations in CF transmembrane conductance regulator (CFTR), a chloride (Cl(-)) channel expressed at the apical membrane of epithelial cells. Absence of functional CFTR from the surface of respiratory cells reduces mucociliary clearance, promoting airways obstruction, chronic infection, and ultimately lung failure. The most frequent mutation, F508del, causes the channel to misfold, triggering its premature degradation and preventing it from reaching the cell surface. Recently, novel small-molecule correctors rescuing plasma membrane localization of F508del-CFTR underwent clinical trials but with limited success. Plausibly, this may be due to the mutant intrinsic plasma membrane (PM) instability. Herein, we show that restoration of F508del-CFTR PM localization by correctors can be dramatically improved through a novel pathway involving stimulation of signaling by the endogenous small GTPase Rac1 via hepatocyte growth factor (HGF). We first show that CFTR anchors to apical actin cytoskeleton (via Ezrin) upon activation of Rac1 signaling through PIP5K and Arp2/3. We then found that such anchoring retains pharmacologically rescued F508del-CFTR at the cell surface, boosting functional restoration by correctors up to 30% of wild-type channel levels in human airway epithelial cells. Our findings reveal that surface anchoring and retention is a major target pathway for CF pharmacotherapy, namely, to achieve maximal restoration of F508del-CFTR in patients in combination with correctors. Moreover, this approach may also translate to other disorders caused by trafficking-deficient surface proteins.
- Preliminary results of the pilot study for Cystic Fibrosis newborn screening in PortugalPublication . Marcão, Ana; Lopes, Lurdes; Carvalho, Ivone; Sousa, Carmen; Fonseca, Helena; Rocha, Hugo; Barreto, Celeste; Vilarinho, LauraThe Portuguese national program for newborn screening started in October 2013 a pilot study for cystic fibrosis. This study will be done in 80,000 Portuguese newborns and will probably last for 1 year long. An IRT/ PAP/ IRT strategy is being used, with 1st IRT and PAP measured in the first newborn screening sample, usually taken between the 3rd and 6th days of life. IRT and PAP cutoff values, in the first sample, are 65 ng/mL and 1.8 ng/mL, respectively. A failsafe procedure was adopted for IRT>100ng/mL (PAP cutoff=0.5ng/mL) and IRT>150ng/mL (immediate request of 2nd sample). Newborns which maintain an elevated IRT in the 2nd sample, usually taken in the 3rd week of life, are sent to a specialized clinical center for sweat test, clinical evaluation and genetic analysis. For the first 52,000 newborns studied, we had a 0.37% recall rate and, after IRT measurement in the 2nd sample, eleven newborns were further evaluated. In two cases, the sweat test and genetic analysis turn out to be negative. Nine patients were confirmed, of which seven were F508del homozygotes. All identified patients have at least one F508del allele, which may indicate that this mutation is more frequent in Portugal than it was previously thought. According with these preliminary results cystic fibrosis may have in Portugal a 1:5,700 approximate frequency.