Browsing by Author "Lemos, MC"
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- Carcinoma anaplásico da tiróide: análise retrospectiva de 12 casosPublication . Martins, TD; Carrilho, F; Leitão, P; Lemos, MC; Campos, MV; Geraldes, E; Carvalheiro, MAnaplastic thyroid tumor is a rare tumor and constitutes 5 to 10% of thyroid carcinomas. Is one of the most aggressive solid tumors and the prognosis is always fatal with a mean survival of 3 to 7 months. The current therapeutics are scarce and inefficacious. A retrospective analysis was performed in 12 clinical cases of anaplastic thyroid tumor observed at the Department of Endocrinology, Diabetes and Metabolism of the University Hospital of Coimbra. We analysed data relative to sex, previous thyroid pathology, clinical signs and symptoms, date of diagnosis, treatment and outcome. In this series, the anaplastic thyroid carcinoma showed to be a highly malignant tumor with a mortality rate of 100% with a survival after the diagnosis between 15 days and 9 months.
- Genetic polymorphism of CYP2D6 influences susceptibility to papillary thyroid cancerPublication . Lemos, MC; Carrilho, F; Rodrigues, F; Coutinho, E; Gomes, L; Carvalheiro, M; Regateiro, FJOBJECTIVE: Xenobiotic-metabolizing enzymes are widely polymorphic and confer interindividual variation in the ability to detoxify carcinogens or to activate pro-carcinogens. A common polymorphism of cytochrome P450 2D6 (CYP2D6) results in lack of enzyme activity and has been associated with an altered susceptibility to several cancers. The aim of this study was to investigate the association between the CYP2D6 poor metaboliser genotype and the risk of papillary thyroid cancer (PTC). DESIGN: Retrospective case-control study. PATIENTS: One hundred and eighty-seven patients with PTC and 256 controls. MEASUREMENTS: Genotyping was performed by PCR and restriction enzyme analysis to detect the presence of the common CYP2D6*4 poor metaboliser allele. RESULTS: The frequency of individuals with the homozygous poor metaboliser genotype was lower in the patient group [1.6 vs. 5.5%, P = 0.037, OR = 0.28 (95% CI 0.09-0.93)]. The CYP2D6*4 allele frequency was also lower in the patient group [13.4 vs. 21.7%, P = 0.002, OR = 0.56 (95% CI 0.39-0.80)]. CONCLUSIONS: The results suggest that the poor metaboliser genotype is associated with a protective effect against PTC. This could be explained by a possible role of CYP2D6 on the metabolic activation of putative environmental chemical thyroid carcinogens or by linkage to another cancer-causing gene. Further research may allow the identification of metabolic risk factors and contribute towards understanding the molecular mechanisms involved in thyroid carcinogenesis.
- Genetic polymorphism of CYP2D6, GSTM1 and NAT2 and susceptibility to haematological neoplasiasPublication . Lemos, MC; Cabrita, FJ; Silva, HA; Vivan, M; Plácido, F; Regateiro, FJXenobiotic-metabolizing enzymes constitute an important line of defence against a variety of carcinogens. Many are polymorphic, constituting the basis for the wide inter-individual variation in metabolic capacity and possibly a source of variation in the susceptibility to chemical-induced carcinogenesis. The aim of this study was to determine the existence of any association between the main genetic polymorphisms of cytochrome P450 2D6 (CYP2D6), glutathione S-transferase M1 (GSTM1) and N-acetyltransferase 2 (NAT2) and an altered risk for haematological neoplasias. A total of 160 patients and 128 controls were genotyped by means of PCR-RFLP-based assays. Mutated alleles comprising CYP2D6*4, GSTM1*0, NAT2*5A, *5B, *5C, *6 and *7 were analysed along with the wild-type alleles. The results showed a higher frequency of CYP2D6 extensive metabolizers carrying two functional alleles in the leukaemia group, when compared with controls (76.6 versus 57.0%, P = 0.008). No differences were found in the case of Hodgkin and non-Hodgkin lymphomas. Analysis of the GSTM1 and NAT2 polymorphisms failed to show an association with any of the neoplasias, although a near significant increase in fast acetylators was also found in the leukaemia group (50.0 versus 35.9%, P = 0.06). The results suggest an association of extensive metabolism with an increased risk for leukaemia, possibly by an increase in the metabolic activation of chemical carcinogens or linkage to another cancer-causing gene. Opposite findings presented in other studies may reflect geographical differences in the type of environmental carcinogens to which different populations are exposed.
- Hiperosmolaridade Diabética: análise retrospectiva de 60 casosPublication . Campos, MV; Bastos, M; Martins, T; Leitão, P; Lemos, MC; Carvalheiro, M; Ruas, AAIMS AND METHODS: Our aims were to determine the frequency of diabetic hyperosmolality (DH) in our Department, its causes, therapeutic implications and evolution. A five-years retrospective study was performed in 60 patients regarding age, sex, type and duration of diabetes mellitus (DM), previous antidiabetic therapy, underlying diseases, biochemical data, precipitating factors, therapeutic management and outcome. RESULTS: The hyperosmolar coma was responsible for 90% of the metabolic comas and for 3% of the diabetic patients. The median age of the cohort was 54.6 +/- 9.4 years, being females 61.7% and males 38.3% In 40% no prior diagnosis of DM was made and in the remaining patients the previous antidiabetic therapy was unknown in 61%. Altered consciousness was found in 90%, being 28% in coma. The metabolic acidosis was detectable in 22.2%, the average glycaemia was 956 +/- 267 mg/dl and the osmolality was 349.4 +/- 34.3 mosm/l. The precipitating factors were: poor metabolic control in all patients (HbA1C 12.5 +/- 2.75%), infections in 76.6%, suspension of antidiabetic therapy in 10% and concomitant hyperglycaemic drugs in 6.6% of patients. The global mortality was 20%. CONCLUSIONS: The majority of the situations could be preventable if an attempted screening and diagnosis of DM was made and precipitating factors avoid or promptly treated.
- Kidney transplantation and diabetes: posttransplantation malignancyPublication . Bastos, M; Baptista, C; Campos, MV; Alves, R; Freitas, L; Bastos, C; Leitão, P; Lemos, MC; Mota, A; Furtado, AL; Carvalheiro, M
- Lack of association of vitamin D receptor gene polymorphisms with susceptibility to type 1 diabetes mellitus in the Portuguese populationPublication . Lemos, MC; Fagulha, A; Coutinho, E; Gomes, L; Bastos, M; Barros, L; Carrilho, F; Geraldes, E; Regateiro, FJ; Carvalheiro, MThe vitamin D receptor (VDR) gene is a candidate gene for susceptibility to autoimmune disorders. Association studies of VDR polymorphisms and risk of type 1 diabetes often produced conflicting results in different ethnic backgrounds. The aim of this study was to test for association between common VDR polymorphisms and the genetic susceptibility to type 1 diabetes in the Portuguese population. We genotyped 207 patients with type 1 diabetes and 249 controls for the FokI T>C (rs10735810), BsmI A>G (rs1544410), ApaI G>T (rs7975232), and TaqI C>T (rs731236) single nucleotide polymorphisms by polymerase chain reaction and restriction fragment length polymorphism analysis. The distribution of VDR genotype, allele, and haplotype frequencies did not differ significantly between patients and controls. These data suggest that the single nucleotide polymorphisms of the VDR gene are unlikely to contribute significantly to type 1 diabetes susceptibility in the Portuguese population.
- Nefropatia diabética: protocolo de estudo pré-transplantação renalPublication . Baptista, C; Bastos, M; Paiva, S; Martins, T; Leitão, P; Lemos, MC; Alves, R; Bastos, C; Mota, A; Carvalheiro, M; Furtado, AL; Ruas, ABetween May 1990 and October 1998, 67 diabetic patients with end-stage renal disease, on dialysis, were submitted to a standardized protocol in order to assess the coexistence and degree of other diabetic and nondiabetic complications that could affect transplantation. Some of the results were analysed. Type 2 diabetic patients had more abnormal results on the lower limbs doppler ultrasound and on the lower limbs arteriography than type 1 (p < 0.05). Type 2 diabetic patients had more cardiovascular complications so the decision to transplant should be taken on a case by case basis.
- Novel FGFR1 mutations in Kallmann syndrome and normosmic idiopathic hypogonadotropic hypogonadism: evidence for the involvement of an alternatively spliced isoformPublication . Gonçalves, C; Bastos, M; Pignatelli, D; Borges, T; Aragüés, JM; Fonseca, F; Pereira, BD; Socorro, S; Lemos, MCOBJECTIVE: To determine the prevalence of fibroblast growth factor receptor 1 (FGFR1) mutations and their predicted functional consequences in patients with idiopathic hypogonadotropic hypogonadism (IHH). DESIGN: Cross-sectional study. SETTING: Multicentric. PATIENT(S): Fifty unrelated patients with IHH (21 with Kallmann syndrome and 29 with normosmic IHH). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Patients were screened for mutations in FGFR1. The functional consequences of mutations were predicted by in silico structural and conservation analysis. RESULT(S): Heterozygous FGFR1 mutations were identified in six (12%) kindreds. These consisted of frameshift mutations (p.Pro33-Alafs*17 and p.Tyr654*) and missense mutations in the signal peptide (p.Trp4Cys), in the D1 extracellular domain (p.Ser96Cys) and in the cytoplasmic tyrosine kinase domain (p.Met719Val). A missense mutation was identified in the alternatively spliced exon 8A (p.Ala353Thr) that exclusively affects the D3 extracellular domain of FGFR1 isoform IIIb. Structure-based and sequence-based prediction methods and the absence of these variants in 200 normal controls were all consistent with a critical role for the mutations in the activity of the receptor. Oligogenic inheritance (FGFR1/CHD7/PROKR2) was found in one patient. CONCLUSION(S): Two FGFR1 isoforms, IIIb and IIIc, result from alternative splicing of exons 8A and 8B, respectively. Loss-of-function of isoform IIIc is a cause of IHH, whereas isoform IIIb is thought to be redundant. Ours is the first report of normosmic IHH associated with a mutation in the alternatively spliced exon 8A and suggests that this disorder can be caused by defects in either of the two alternatively spliced FGFR1 isoforms
- Polimorfismos do gene CYP2D6 estão associados a uma susceptibilidade para os tumores da hipófisePublication . Gomes, L; Lemos, MC; Paiva, I; Ribeiro, C; Carvalheiro, M; Regateiro, FJSeveral polymorphisms of drug-metabolizing enzymes have been implicated in the susceptibility to tumor development. The role of the CYP2D6, GSTM1 and GSTT1 genes has been extensively studied, with alleles conferring different metabolic efficiencies and tumor risk. We studied the relationship between the main polymorphisms of these genes and the susceptibility to develop pituitary tumors, by performing a case-control study comprising 235 patients and 256 controls which were genotyped by means of PCR-RFLP based assays. Frequencies of the CYP2D6*1 and of the poor metabolizer allele CYP2D6*4, were determined along with the frequencies of the GSTM1 and GSTT1 null genotypes. CYP2D6 genotype frequencies were similar in patients and controls (p=0.087). CYP2D6*1 and CYP2D6*4 allele frequencies were 83.8%, 16.2% in cases and 78.3%, 21.7% in controls, showing a significant difference between the two groups (p=0.012). There were no significant differences between the frequencies of the GSTM1 and GSTT1 null genotypes in both groups. No association was found between histological type and any of the studied polymorphisms. Our data suggest an association of the CYP2D6*1 allele and the susceptibility to pituitary adenomas, which could be due to an increased metabolism of unidentified procarcinogens or to linkage disequilibrium with another gene involved in pituitary tumorigenesis.
- PROP1 gene analysis in Portuguese patients with combined pituitary hormone deficiencyPublication . Lemos, MC; Gomes, L; Bastos, M; Leite, V; Limbert, E; Carvalho, D; Bacelar, C; Monteiro, M; Fonseca, F; Agapito, A; Castro, JJ; Regateiro, FJ; Carvalheiro, MOBJECTIVE: Mutations of the PROP1 gene lead to combined pituitary hormone deficiency (CPHD), which is characterized by a deficiency of GH, TSH, LH/FSH, PRL and, less frequently, ACTH. This study was undertaken to investigate the molecular defect in a cohort of patients with CPHD. DESIGN, PATIENTS AND MEASUREMENTS: A multicentric study involving 46 cases of CPHD (17 familial cases belonging to seven kindreds and 29 sporadic cases) selected on the basis of clinical and hormonal evidence of GH deficiency, central hypothyroidism and hypogonadotrophic hypogonadism, in the absence of an identified cause of hypopituitarism. Mutations of PROP1 were investigated by DNA sequencing. Clinical, hormonal and neuroradiological data were collected at each centre. RESULTS: PROP1 mutations were identified in all familial cases: five kindreds presented a c. 301-302delAG mutation, one kindred presented a c. 358C --> T (R120C) mutation and one presented a previously unreported initiation codon mutation, c. 2T --> C. Of the 29 sporadic cases, only two (6.9%) presented PROP1 germline mutations (c. 301-302delAG, in both). Phenotypic variability was observed among patients with the same mutations, particularly the presence and age of onset of hypocortisolism, the levels of PRL and the results of pituitary imaging. One patient presented a sellar mass that persisted into adulthood. CONCLUSIONS: This is the first report of a mutation in the initiation codon of the PROP1 gene and this further expands the spectrum of known mutations responsible for CPHD. The low mutation frequency observed in sporadic cases may be due to the involvement of other unidentified acquired or genetic causes