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- Trapped modes in a fluid with three layers topped by a rigid lidPublication . Cal, Filipe; Dias, Gonçalo A. S.; Pereira, Bruno M. M.We consider trapping of linear water waves by a submerged horizontal cylinder in a three-layer fluid topped by a rigid lid. Trapped modes correspond to time harmonic oscillations with finite energy of the fluid surrounding a submerged structure and can be found as eigenfunctions of a certain spectral boundary-value problem. Our main result is a geometric condition relating the cross sections of the submerged parts of the obstacles and the line integrals along the parts of the interfaces pierced by the obstacles and guaranteeing the existence of trapped modes: This follows from variational techniques applied to a suitable operator formulation of the problem. Several examples of structures (piercing or not the interfaces between the fluid layers) satisfying the condition and supporting trapped modes are given.
- Neurodegeneration and choroidal vascular features on OCT in the progression to advanced age-related macular degenerationPublication . Costa, Inês; Carvalho, Ana; Andrade, Helton; Pereira, Bruno; Camacho, PedroAim: To quantify and compare longitudinal thickness changes of the ganglion cell complex (GCC) and the choroid in patients with different patterns of age-related macular degeneration (AMD) progression. Methods: Retrospective cohort analysis of anonymized data from participants aged 50y or more and diagnosed with early/intermediate AMD in at least one eye (with no evidence of advanced AMD). A total of 64 participants were included from the Instituto de Retina de Lisboa (IRL) study (IPL/2022/MetAllAMD_ESTeSL) and divided into 4 groups according to the Rotterdam classification for AMD. Spectral-domain optical coherence tomography (SD-OCT) was used to assess and quantify GCC and choroid thickness at two-time points (first visit vs last visit) with a minimum interval of 3y. Results: In the GCC inner ring, a thinner thickness (P=0.001) was observed in the atrophic AMD group (51.3±21.4 µm) compared to the early AMD (84.3±11.5 µm), intermediate AMD (77.6±16.1 µm) and neovascular AMD (88.9±16.3 µm) groups. Choroidal thickness quantification showed a generalized reduction in the central circle (P=0.002) and inner ring (P=0.001). Slight reductions in retinal thickness were more accentuated in the inner ring in the atrophic AMD (-13%; P<0.01). Conclusion: The variation of the analyzed structures could be an indicator of the risk of progression with neurodegenerative (GCC) or vascular (choroid) patterns in the intermediate and atrophic AMD. The quantification of both structures can provide important information about the risk of disease progression in the early and intermediate stages but also for the evolution pattern into late stages (atrophic or neovascular).
- DNA methyltransferase expression (DNMT1, DNMT3a, and DNMT3b) as a potential biomarker in age-related macular degenerationPublication . Camacho, Pedro; Ribeiro, Edna; Pereira, Bruno; Nascimento, João; Rosa, Paulo Caldeira; Henriques, José; Barrão, Sandra; Sadio, Silvia; Quendera, Bruno; Delgadinho, Mariana; Ginete, Catarina; Neves Delgadinho, Mariana Isabel; Honrado Ginete, Ana Catarina; Silva, Carina; Brito, MiguelBackground/Objectives: Age-related macular degeneration (AMD) is a global cause of vision loss, with limited therapeutic options highlighting the need for effective biomarkers. This study aimed to characterize plasma DNA methyltransferase expression (DNMT1, DNMT3A, and DNMT3B) in AMD patients and explore divergent expression patterns across different stages of AMD. Methods: Thirty-eight AMD patients were prospectively enrolled and stratified by disease severity: eAMD, iAMD, nAMD, and aAMD. Comprehensive ophthalmological assessments included best-corrected visual acuity, digital color fundus photographs, and Spectral Domain Optical Coherence Tomography. Peripheral blood samples were collected for RNA extraction and qRT-PCR to access epigenetic effectors’ transcriptional expression, namely DNMT1, DNMT3A, and DNMT3B genes. The collected data were analyzed using IBM SPSS 29. Results: DNMT1 expression was significantly downregulated in late AMD (−0.186 ± 0.341) compared to early/intermediate AMD (0.026 ± 0.246). Within late AMD, aAMD exhibited a marked downregulation of DNMT1 (−0.375 ± 0.047) compared to nAMD (0.129 ± 0.392). DNMT3A and DNMT3B showed similar divergent expression patterns, correlating with disease stage. Conclusions: This study identified stage-specific transcriptional differences in DNMT expression, emphasizing its potential as a biomarker for AMD progression and a target for future research into personalized therapeutic strategies.