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- Homocysteine metabolism in children and adolescents: influence of age on plasma biomarkers and correspondent genotype interactionsPublication . Araújo, Helena Caldeira; Ramos, Ruben; Florindo, Cristina; Rivera, Isabel; Castro, Rita; Almeida, Isabel Tavares deBackground: Imbalance of homocysteine (Hcy) metabolism links with several pathologies; nevertheless, it is poorly characterized in pediatric populations. This study investigated the impact of age on plasma concentrations of Hcy and relevant biomarkers along with correspondent genotype interactions. Methods: A healthy pediatric cohort aged 9 (n = 195) and 17 (n = 128) years old (yo) was studied. Immunoassays and GC-MS-SIM-mode quantified plasma levels of Hcy and biomarkers. PCR-RFLP or quantitative-PCR assays assessed common variations in related genes. Results: Age impacted on levels of Hcy and metabolic markers: older children presented with the lowest folates and total-cobalamin (tCbl), while with the highest Hcy concentrations, whereas methylmalonic acid (MMA) and holotranscobalamin (Holo-TC) levels remained similar in 9-yo and 17-yo children. The relationships between B-vitamins and metabolic markers were also dependent on age. Only in the older children, MMA correlated with tCbl and Holo-TC, and MMA levels were markedly higher in the 17-yo subjects presenting with the lowest quartiles of Holo-TC concentrations. Lastly, age also impacted on the correlations between genotype and biomarkers. In the 17-yo group, however not in the 9-yo children, tHcy differed between MTHFR 677 genotypes, with subjects who had the MTHFR 677TT genotype displaying the highest tHcy concentrations. Conclusions: Age impacts on the Hcy metabolism dynamics in a pediatric population.
- Profiling the occurrence of biogenic amines in different types of tuna samples using an improved analytical approachPublication . Pataca, Joanna K.G.; Porto-Figueira, Priscilla; Pereira, Jorge A. M.; Caldeira, Helena; Câmara, José S.Food deterioration caused by microbial agents often involve the formation of biogenic amines (BAs), which can have harmful effects on human health. In this study a set of BAs - tryptamine, cadaverine, putrescine, spermine, histamine, tyramine, and spermidine, were simultaneously analysed to monitor their occurrence in different types of tuna samples. An improved extraction approach involving ultrasound-assisted microextraction (USAμET) followed by derivatization with dansyl chloride (DnsCl) and analysis by ultrahigh performance liquid chroma tography (UHPLC) with fluorescence detection was validated for BAs quantification. The performance of the USAμET/UHPLC-FLD was assessed by studying the limits of detection (LOD) and quantification (LOQ), linear dynamic range (LDR), precision (intra and inter-day) and matrix effect (ME). Good linearity (r2 > 0.98), LODs (from 0.98 to 8.57 mg kg− 1 ) and LOQs (3.20–25.6 mg kg− 1 ) were achieved for all BAs analysed. Recoveries ranged from 76% to 106%, with relative standard deviations (RSD) lower than 5.0%. ME was determined from 7.52 to 50% and the intra and inter-day precisions ranged from 4.7 to 11.6% and 5.5–14.2%, respectively. BAs levels varied significantly from 4.09 ± 0.8 mg kg− 1 of putrescine in olive oil canned samples to 577.9 ± 5.9 mg kg− 1 of cadaverine in natural canned samples. Tryptamine and tyramine were not detected in any of the samples analysed, while spermine and spermidine were found in 85.7% of the assayed tuna samples. Cadaverine was the most dominant BA with concentrations ranging from 54.3 ± 2.5 mg kg− 1 , in olive oil canned tuna, to 577.9 ± 5.9 mg kg− 1 , in natural canned samples, whereas putrescine had the lowest concentration (average 6.9 ± 2.5 mg kg− 1 ). The validated methodology revealed important improvements in terms of simplification of the experi mental layout, expressed in the low sample and reagent amounts, in addition to less time-consuming and labour intensive requirements that did not compromise the analytical performance.
- Vimentin diversity in health and diseasePublication . Danielsson, Frida; Peterson, McKenzie; Araújo, Helena Caldeira; Lautenschläger, Franziska; Gad, Annica Karin BrittVimentin is a protein that has been linked to a large variety of pathophysiological conditions, including cataracts, Crohn’s disease, rheumatoid arthritis, HIV and cancer. Vimentin has also been shown to regulate a wide spectrum of basic cellular functions. In cells, vimentin assembles into a network of filaments that spans the cytoplasm. It can also be found in smaller, non-filamentous forms that can localise both within cells and within the extracellular microenvironment. The vimentin structure can be altered by subunit exchange, cleavage into different sizes, re-annealing, post-translational modifications and interacting proteins. Together with the observation that different domains of vimentin might have evolved under different selection pressures that defined distinct biological functions for different parts of the protein, the many diverse variants of vimentin might be the cause of its functional diversity. A number of review articles have focussed on the biology and medical aspects of intermediate filament proteins without particular commitment to vimentin, and other reviews have focussed on intermediate filaments in an in vitro context. In contrast, the present review focusses almost exclusively on vimentin, and covers both ex vivo and in vivo data from tissue culture and from living organisms, including a summary of the many phenotypes of vimentin knockout animals. Our aim is to provide a comprehensive overview of the current understanding of the many diverse aspects of vimentin, from biochemical, mechanical, cellular, systems biology and medical perspectives.