Browsing by Author "Mendes, Filipa"
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- In vivo pretargeting based on cysteine-selective antibody modification with IEDDA bioorthogonal handles for click chemistryPublication . Ferreira, Vera F. C.; Oliveira, Bruno; D'Onofrio, Alice; Farinha, Carlos; Gano, Lurdes; Paulo, António; Bernardes, Gonçalo J. L.; Mendes, FilipaPretargeted imaging has emerged as an effective multistep strategy aiming to improve imaging contrast and reduce patient radiation exposure through decoupling of the radioactivity from the targeting vector. The inverse electron-demand Diels-Alder (IEDDA) reaction between a trans-cyclooctene (TCO)-conjugated antibody and a labeled tetrazine holds great promise for pretargeted imaging applications due to its bioorthogonality, rapid kinetics under mild conditions, and formation of stable products. Herein, we describe the use of functionalized carbonylacrylic reagents for site-specific incorporation of TCO onto a human epidermal growth factor receptor 2 (HER2) antibody (THIOMAB) containing an engineered unpaired cysteine residue, generating homogeneous conjugates. Precise labeling of THIOMAB-TCO with a fluorescent or radiolabeled tetrazine revealed the potential of the TCO-functionalized antibody for imaging the HER2 after pretargeting in a cellular context in a HER2 positive breast cancer cell line. Control studies with MDA-MD-231 cells, which do not express HER2, further confirmed the target specificity of the modified antibody. THIOMAB-TCO was also evaluated in vivo after pretargeting and subsequent administration of an 111In-labeled tetrazine. Biodistribution studies in breast cancer tumor-bearing mice showed a significant activity accumulation on HER2+ tumors, which was 2.6-fold higher than in HER2- tumors. Additionally, biodistribution studies with THIOMAB without the TCO handle also resulted in a decreased uptake of 111In-DOTA-Tz on HER2+ tumors. Altogether, these results clearly indicate the occurrence of the click reaction at the tumor site, i.e., pretargeting of SK-BR-3 HER2-expressing cells with THIOMAB-TCO and reaction through the TCO moiety present in the antibody. The combined advantages of site-selectivity and stability of TCO tagged-antibodies could allow application of biorthogonal chemistry strategies for pretargeting imaging with minimal side-reactions and background.
- Plasmatic Klotho and FGF23 levels as biomarkers of CKD-associated cardiac disease in type 2 diabetic patientsPublication . Silva, Ana; Mendes, Filipa; Carias, Eduarda; Gonçalves, Rui; Fragoso, André; Dias, Carolina; Tavares, Nelson; Café, Hugo; Santos, Nélio; Rato, Fátima; Leão Neves, Pedro; Almeida, EdgarBackground: Research over the past decade has focused on the role of Klotho as a cardio protective agent that prevents the effects of aging on the heart and reduces the burden of cardiovascular disease CVD. The role of the interaction between fibroblast growth factor 23-(FGF-23)/Klotho in Klotho-mediated actions is still under debate. The main objective was to ascertain the potential use of plasmatic Klotho and FGF23 as markers for CKD-associated cardiac disease and mortality. Methods: This was a prospective analysis conducted in an outpatient diabetic nephropathy clinic, enrolling 107 diabetic patients with stage 2⁻3 CKD. Patients were divided into three groups according to their left ventricular mass index and relative wall thickness. Results: Multinomial regression analysis demonstrated that low Klotho and higher FGF-23 levels were linked to a greater risk of concentric hypertrophy. In the generalized linear model (GLM), Klotho, FGF-23 and cardiac geometry groups were statistically significant as independent variables of cardiovascular hospitalization (p = 0.007). According to the Cox regression model, fatal cardiovascular events were associated with the following cardiac geometric classifications; eccentric hypertrophy (p = 0.050); concentric hypertrophy (p = 0.041), and serum phosphate ≥ 3.6 mg/dL (p = 0.025), FGF-23 ≥ 168 (p = 0.0149), α-klotho < 313 (p = 0.044). Conclusions: In our population, Klotho and FGF23 are associated with cardiovascular risk in the early stages of CKD.
- The upsizing of the São Tomé seed dispersal network by introduced animalsPublication . Heleno, Ruben H.; Mendes, Filipa; Coelho, Ana P.; Ramos, Jaime A.; M. Palmeirim, Jorge; Rainho, Ana; F. De Lima, RicardoBiological invasions are a major threat to global biodiversity with particularly deleterious consequences on oceanic islands. The introduction of large terrestrial animals – generally absent on islands – can disrupt important ecosystem functions, such as the dispersal of native seeds. However, while the consequences of plant invasions received much attention, the potential of introduced animals to change insular seed dispersal networks remains largely unknown. Here, we collated evidence from five sampling methods to assemble qualitative and quantitative, multi-guild seed dispersal network for the island of São Tomé (Gulf of Guinea) and explore whether native and introduced seed dispersers consistently differ in their topological roles, in their gape width and in the size of the dispersed seeds. Our network included 428 interactions between 23 dispersers (14 birds, 2 bats, 1 snake and 6 non-flying mammals) and 133 plant species. Each method (direct observations, identification of seeds in droppings and stomachs, questionnaires and literature review) was particularly informative for a small group of dispersers, thus rendering largely complementary information. Native and introduced dispersers did not differ in their topological position in either qualitative or quantitative networks (linkage level, specialization d' and species strength). However, introduced dispersers tend to have much larger gape widths and to disperse significantly larger seeds. Our results point to a general upsizing of the seed dispersal network in the island of São Tomé driven by the recent arrival of large, introduced animals. We argue that this pattern is likely common on other oceanic islands where introduced dispersers might counteract the general pattern of seed dispersal downsizing resulting from the selective extinction of larger animals.
- Tricarbonyl M(I) (M = Re, 99mTc) complexes bearing acridine fluorophores : synthesis, characterization, DNA interaction studies and nuclear targetingPublication . Esteves, Teresa; Xavier, Catarina; Gama, Sofia; Mendes, Filipa; Raposinho, Paula D.; Marques, Fernanda; Paulo, António; Pessoa, João Costa; Rino, José; Viola, Giampietro; Santos, IsabelNew pyrazolyl-diamine ligands with acridine derivatives at the 4-position of the pyrazolyl ring were synthesized and characterized (L1 and L2). Coordination towards the fac-[M(CO)3]+ (M = Re, 99mTc) led to complexes fac-[M(CO)3(κ3-L)] (L = L1: M = Re1, Tc1; L = L2: M = Re2, Tc2). The interaction of the novel pyrazolyl-diamine ligands (L1 and L2) and rhenium(I) complexes (Re1 and Re2) with calf thymus DNA (CT-DNA) was investigated by a variety of techniques, namely UV-visible , fluorescence spectroscopy and circular and linear dichroism . Compounds L1 and Re1 have moderate affinity to CT-DNA and bind to DNA by intercalation, while L2 and Re2 have a poor affinity for CT-DNA. Moreover, LD measurements showed that L1 and Re1 act as perfect intercalators . By confocal fluorescence microscopy we found that L1 and Re1 internalize and localize in the nucleus of B16F1 murine melanoma cells . The congener Tc1 complex also targets the cell nucleus exhibiting a time-dependent cellular uptake and a fast and high nuclear internalization (67.2% of activity after 30 min). Plasmid DNA studies have shown that Tc1 converts supercoiled (sc) puc19 DNA to the open circular (oc) form.