Browsing by Author "Pereira, M."
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- Advances in the genotyping of thrombosis genetic risk factors: clinical and laboratory implications.Publication . Cabeda, J.; Pereira, M.; Oliveira, J.; Estevinho, A.; Pereira, I.; Morais, S.; Justiça, B.; Campos, M.Since FV-Leiden polymorphism was first described in 1994, a growing number of polymorphic loci have been identified in association with increased genetic risk for thrombophilia. Often however, these risk factors have been studied in isolation of the remaining known phenotype linked polymorphisms. This fact has, at least in part, been justified by the laborious techniques traditionally used in the genotyping studies, as well as its relatively high costs. Another major problem concerning these studies has been the non-negligible incidence of dubious genotypes, resulting from the manual, labour intensive techniques applied, and their sometimes difficult to read output's. These difficulties have also hampered the widespread use of genotyping data in the clinical assessment of the genetic risk levels both in patients and their relatives, leaving some clinicians less than convinced about its clinical usefulness. Recently however, the introduction of new genetic techniques in the clinical genetics laboratory has started to change this picture. Most notably, the advent of Real-time-PCR has brought the possibility of genotyping patients and controls at a large scale, with increased specificity, automation and speed. Moreover, the use of these techniques in the clinical genetics setting has not only increased the quality of the results, but most importantly has also increased our capability of answering questions at a deeper level. Among the new questions that can now be answered without increased costs and uncertainty is the study of the association of genetic risk factors in thrombophilia. Our results show that indeed even common polymorphic loci may increase our ability to further discriminate the genetic thrombosis risk of individual patients and relatives. It must however be noted that the innovation level in the clinical genetics lab is just starting to grow. In fact we haven't even started to experience the advantages brought about by the genome program, and its massive identification of SNP's. The technology to test these is also presently being refined, and is expected to go from research to the clinical lab in the near future. Only then, can we expect to define with high certainty the combined genetic risks for such complex pathologies as the thrombophilias.
- Anemia ferropriva refratária ao ferro: Uma entidade clínica de descrição e caracterização molecular recentesPublication . Raposo, F.; Melo, T.; Costa, M.; Pereira, M.; Cleto, E.; Costa, E:; Barbot, J.A anemia por défice de ferro é um importante problema de saúde a nível mundial. Até há poucos anos atrás, considerava--se este défice como sendo de natureza exclusivamente adquirida e os erros de metabolismo eram atribuídos unicamente a patologia de sobrecarga. A descoberta da molécula de hepcidina e a descrição e caracterização molecular da anemia ferropriva refratária ao ferro veio contrariar essa anterior convicção. Os autores apresentam os casos clínicos de duas doentes, primas em segundo grau, com diagnóstico de anemia ferropriva refratária ao ferro, com o objetivo de alertar para esta etiologia, aquando do diagnóstico de uma anemia ferropriva de etiologia desconhecida e refratária a terapêutica com ferro oral e endovenoso
- Association between Polymorphisms in Antioxidant Genes and Inflammatory Bowel DiseasePublication . Costa-Pereira, C.; Durães, C.; Coelho, R.; Grácio, D.; Silva, M.; Peixoto, A.; Lago, P.; Pereira, M.; Catarino, T.; Pinho, S.; Teixeira, J.; Macedo, G.; Annese, V.; Magro, F.Inflammation is the driving force in inflammatory bowel disease (IBD) and its link to oxidative stress and carcinogenesis has long been accepted. The antioxidant system of the intestinal mucosa in IBD is compromised resulting in increased oxidative injury. This defective antioxidant system may be the result of genetic variants in antioxidant genes, which can represent susceptibility factors for IBD, namely Crohn's disease (CD) and ulcerative colitis (UC). Single nucleotide polymorphisms (SNPs) in the antioxidant genes SOD2 (rs4880) and GPX1 (rs1050450) were genotyped in a Portuguese population comprising 436 Crohn's disease and 367 ulcerative colitis patients, and 434 healthy controls. We found that the AA genotype in GPX1 is associated with ulcerative colitis (OR = 1.93, adjusted P-value = 0.037). Moreover, we found nominal significant associations between SOD2 and Crohn's disease susceptibility and disease subphenotypes but these did not withstand the correction for multiple testing. These findings indicate a possible link between disease phenotypes and antioxidant genes. These results suggest a potential role for antioxidant genes in IBD pathogenesis and should be considered in future association studies.
- Combined Pancreas-Kidney Transplantation: A New Program in Portugal, Results From the First 12 CasesPublication . Martins, L.; Henriques, A.; Dias, L.; Ventura, A.; Seca, R.; Almeida, R.; Dores, J.; Bacelar, C.; Oliveira, F.; Lhamas, A.; Amil, M.; Rua, F.; Coelho, T.; Esteves, S.; Ribeiro, A.; Pereira, R.; Sarmento, A.; Teixeira, M.; Pereira, M.Transplant Proc. 2003 May;35(3):1107-8. Combined pancreas-kidney transplantation: a new program in Portugal, results from the first 12 cases. Martins L, Henriques A, Dias L, Ventura A, Seca R, Almeida R, Dores J, Bacelar C, Oliveira F, Lhamas A, Amil M, Rua F, Coelho T, Esteves S, Ribeiro A, Pereira R, Sarmento A, Teixeira M, Pereira M. Transplantation Department, Hospital Santo António, 4050, Porto, Portugal. lasalete@clix.pt PMID: 12947877 [PubMed - indexed for MEDLINE]
- DEFINIÇÃO DE HIPERTENSÃO: O IMPACTO DO NÚMERO DE VISITAS POR MEDIÇÃO DA PRESSÃO ARTERIALPublication . Figueiredo, D.; Azevedo, A.; Pereira, M.; Barros, H.
- Eritroblastopenia transitória da infância: atitude expectante face a uma anemia gravePublication . Pereira, M.; Bergantim, R.; Costa, E.; Morais, L.; Lavrador, V.; Barbot, J.Introdução: A eritroblastopenia transitória da infância (ETI) é uma condição aguda caracterizada por anemia moderada a grave e reticulocitopenia, secundárias a uma supressão temporária da eritropoiese. A etiologia é desconhecida, embora ocorra associação com uma infecção vírica em cerca de metade dos casos. Tipicamente, apresenta um curso benigno e auto-limitado, necessitando apenas de vigilância da evolução clínica. Caso clínico: Descreve-se o caso clínico de uma menina com três anos de idade, internada por infecção respiratória alta e ETI. O seu quadro hematológico era caracterizado por anemia com hemoglobina de 7.1 g/dl e reticulocitopenia, sem alterações nas outras linhas celulares. A evolução foi favorável, com recuperação espontânea ao fim de três semanas. Conclusão: O reconhecimento desta entidade hematológica benigna, distinguindo-a de outras formas de anemia arregenerativa, pode evitar o recurso a procedimentos diagnósticos e terapêuticos desnecessários. ABSTRACT Introduction: Transient erythroblastopenia of childhood (TEC) is an acquired, acute disorder, characterized by moderate to severe anemia and reticulocytopenia, secondary to a temporary suppression of red blood cell production. The etiology of TEC remains unknown, although an association with viral infections has been proposed. It is self-resolving and careful observation is the only medical support needed in most cases. Case report: The authors describe the case of a three-year-old girl who was admitted with an upper respiratory tract infection and TEC. Initial signs were anemia, with a 7.1 g/dl hemoglobin level and reticulocytopenia, without another hematologic abnormality. Spontaneous recovery occurred after three weeks. Conclusion: A better knowledge of this benign hematologic disorder of childhood, distinguishing TEC from other causes of non-regenerative anemia, can prevent unnecessary diagnostic procedures and treatment.
- Glycans as Key Checkpoints of T Cell Activity and FunctionPublication . Pereira, M.; Alves, I.; Vicente, M.; Campar, A.; Silva, M.; Padrão, N.; Pinto, V.; Fernandes, Â.; Dias, A.; Pinho, S.The immune system is highly controlled and fine-tuned by glycosylation, through the addition of a diversity of carbohydrates structures (glycans) to virtually all immune cell receptors. Despite a relative backlog in understanding the importance of glycans in the immune system, due to its inherent complexity, remarkable findings have been highlighting the essential contributions of glycosylation in the regulation of both innate and adaptive immune responses with important implications in the pathogenesis of major diseases such as autoimmunity and cancer. Glycans are implicated in fundamental cellular and molecular processes that regulate both stimulatory and inhibitory immune pathways. Besides being actively involved in pathogen recognition through interaction with glycan-binding proteins (such as C-type lectins), glycans have been also shown to regulate key pathophysiological steps within T cell biology such as T cell development and thymocyte selection; T cell activity and signaling as well as T cell differentiation and proliferation. These effects of glycans in T cells functions highlight their importance as determinants of either self-tolerance or T cell hyper-responsiveness which ultimately might be implicated in the creation of tolerogenic pathways in cancer or loss of immunological tolerance in autoimmunity. This review discusses how specific glycans (with a focus on N-linked glycans) act as regulators of T cell biology and their implications in disease.
- Homocysteine levels in pediatric renal transplant recipients.Publication . Mota, C.; Fonseca, Isabel; Santos, M.J.; Costa, T.; Faria, M.S.; Henriques, A.C.; Sarmento, A.M.; Pereira, E.; Pereira, M.Transplant Proc. 2003 May;35(3):1093-5. Homocysteine levels in pediatric renal transplant recipients. Mota C, Fonseca I, Santos MJ, Costa T, Faria MS, Henriques AC, Sarmento AM, Pereira E, Pereira M. Department of Paediatric Nephrology, Maria Pia Children's Hospital, R. da Boavista, 827, 4050-111, Porto, Portugal. ccmotacosta@hotmail.com PMID: 12947872 [PubMed - indexed for MEDLINE
- Hyperhomocysteinemia in Renal Transplantation: Preliminary ResultsPublication . Fonseca, Isabel; Queirós, J; Santos, M.J.; Mendonça, D.; Henriques, A. C.; Sarmento, A.M.; Santos, A.C.; Guimarães, S.; Pereira, M.Cardiovascular disease (CVD) is a major cause of morbidity and mortality after renal transplantation (RT).[1] and [2] The excess risk of CVD in RT is due in part to a higher prevalence of established atherosclerotic risk factors, including hypertension, dyslipidemia, diabetes, obesity, and physical inactivity.[1] and [2] However, some renal-related risk factors like immunosuppressive medication and residual renal insufficiency also contribute to this excess CVD risk and may complicate the management of dyslipidemia and hypertension in this population.[1] and [2] Accordingly, there is a compelling need to identify and safely manage other putative CVD risk factors among RT patients. Elevated plasma homocysteine is emerging as an important risk factor for cardiovascular disease in general populations.[3] and 4 R Clarke, L Daly and K Robinson et al., N Engl J Med 324 (1991), p. 1149. View Record in Scopus | Cited By in Scopus (1372)[4] Some studies have demonstrated that hyperhomocysteinemia is present in patients with impaired renal function and is associated with CVD.[5], [6] and [7] Only a small number of studies are available on the prevalence and determinants of hyperhomocysteinemia in renal transplant recipients.[8], [9], [10], [11], [12], [13], [14] and [15] We undertook this study to 1. estimate the prevalence of hyperhomocysteinemia in renal transplant recipients; 2. examine the relationships between plasma total homocysteine (tHcy) and its metabolic determinants vitamin B6, vitamin B12, and folic acid; and 3. identify other determinants of tHcy.
- Metabolic control of T cell immune response through glycans in inflammatory bowel diseasePublication . Dias, A.; Correia, A.; Pereira, M.; Almeida, C.; Alves, I.; Pinto, V.; Catarino, T.; Mendes, N.; Leander, M.; Oliva-Teles, M.; Maia, L.; Delerue-Matos, C.; Taniguchi, N.i; Lima, Margarida; Pedroto, I.; Marcos-Pinto, Ricardo; Lago, P.; Reis, C.; Vilanova, M.; Pinho, S.Mucosal T lymphocytes from patients with ulcerative colitis (UC) were previously shown to display a deficiency in branched N-glycosylation associated with disease severity. However, whether this glycosylation pathway shapes the course of the T cell response constituting a targeted-specific mechanism in UC remains largely unknown. In this study, we demonstrated that metabolic supplementation of ex vivo mucosal T cells from patients with active UC with N-acetylglucosamine (GlcNAc) resulted in enhancement of branched N-glycosylation in the T cell receptor (TCR), leading to suppression of T cell growth, inhibition of the T helper 1 (Th1)/Th17 immune response, and controlled T cell activity. We further demonstrated that mouse models displaying a deficiency in the branched N-glycosylation pathway (MGAT5-/-, MGAT5+/-) exhibited increased susceptibility to severe forms of colitis and early-onset disease. Importantly, the treatment of these mice with GlcNAc reduced disease severity and suppressed disease progression due to a controlled T cell-mediated immune response at the intestinal mucosa. In conclusion, our human ex vivo and preclinical results demonstrate the targeted-specific immunomodulatory properties of this simple glycan, proposing a therapeutic approach for patients with UC.