Browsing by Author "Marinho, A"
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- Differences in nevirapine biotransformation as a factor for its sex-dependent dimorphic profile of adverse drug reactions.Publication . Marinho, A; Rodrigues, P; Caixas, U; Antunes, A; Branco, T; Hargivan, S; Marques, M; Monteiro, E; Pereira, SOBJECTIVES: Nevirapine is widely used for the treatment of HIV-1 infection; however, its chronic use has been associated with severe liver and skin toxicity. Women are at increased risk for these toxic events, but the reasons for the sex-related differences are unclear. Disparities in the biotransformation of nevirapine and the generation of toxic metabolites between men and women might be the underlying cause. The present work aimed to explore sex differences in nevirapine biotransformation as a potential factor in nevirapine-induced toxicity. METHODS: All included subjects were adults who had been receiving 400 mg of nevirapine once daily for at least 1 month. Blood samples were collected and the levels of nevirapine and its phase I metabolites were quantified by HPLC. Anthropometric and clinical data, and nevirapine metabolite profiles, were assessed for sex-related differences. RESULTS: A total of 52 patients were included (63% were men). Body weight was lower in women (P = 0.028) and female sex was associated with higher alkaline phosphatase (P = 0.036) and lactate dehydrogenase (P = 0.037) levels. The plasma concentrations of nevirapine (P = 0.030) and the metabolite 3-hydroxy-nevirapine (P = 0.035), as well as the proportions of the metabolites 12-hydroxy-nevirapine (P = 0.037) and 3-hydroxy-nevirapine (P = 0.001), were higher in women, when adjusted for body weight. CONCLUSIONS: There was a sex-dependent variation in nevirapine biotransformation, particularly in the generation of the 12-hydroxy-nevirapine and 3-hydroxy-nevirapine metabolites. These data are consistent with the sex-dependent formation of toxic reactive metabolites, which may contribute to the sex-dependent dimorphic profile of nevirapine toxicity.
- Evidence for nevirapine bioactivation in man: Searching for the first step in the mechanism of nevirapine toxicity.Publication . Caixas, U; Antunes, A; Marinho, A; Godinho, A; Grilo, N; Marques, M; Oliveira, M; Branco, T; Monteiro, E; Pereira, SNevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor used against human immunodeficiency virus type-1 (HIV-1), mostly to prevent mother-to-child HIV-1 transmission in developing countries. Despite its clinical efficacy, NVP administration is associated with a variety of toxic responses that include hepatotoxicity and skin rash. Although the reasons for the adverse effects of NVP administration are still unclear, increasing evidence supports the involvement of metabolic activation to reactive electrophiles. In particular, Phase II activation of the NVP metabolite 12-hydroxy-NVP is thought to mediate NVP binding to bionucleophiles, which may be at the onset of toxicity. In the present study, we investigated the nature and specific locations of the covalent adducts produced in human serum albumin and human hemoglobin by reaction in vitro with the synthetic model electrophile 12-mesyloxy-NVP, used as a surrogate for the Phase II metabolite 12-sulfoxy-NVP. Multiple sites of modification were identified by two different mass spectrometry-based methodologies, liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and matrix-assisted laser desorption ionization tandem mass spectrometry (MALDI-TOF-TOF-MS). These two distinct methodologies, which in some instances afforded complementary information, allowed the identification of multiple adducts involving cysteine, lysine, tryptophan, histidine, serine, and the N-terminal valine of hemoglobin. Tryptophan, which is not a common site of covalent protein modification, was the NVP-modified amino acid residue detected in the two proteins and consistently identified by both LC-ESI-MS/MS and MALDI-TOF-TOF-MS. The propensity of tryptophan to react with the NVP-derived electrophile is further emphasized by the fact that human serum albumin possesses a single tryptophan residue, which suggests a remarkable selectivity that may be useful for biomonitoring purposes. Likewise, the NVP adduct with the terminal valine of hemoglobin, detected by LC-ESI-MS/MS after N-alkyl Edman degradation, appears as an easily assessed marker of NVP binding to proteins. Our results demonstrate the merits and complementarity of the two MS-based methodologies for the characterization of protein binding by NVP and suggest a series of plausible biomarkers of NVP toxicity that should be useful in the monitoring of toxicity effects in patients administered NVP.
- Not All ENT Granulomas Are Wegener's - Keep Tuberculosis in Mind.Publication . Pedro, B; Meleiro, M; Marinho, AMycobacterium tuberculosis affects the middle ear in rare cases and is a challenging diagnosis. In this case, we present a 57-year-old patient diagnosed with anti-neutrophil cytoplasmic antibody (ANCA)-negative granulomatosis with polyangiitis (GPA) following a biopsy result of nasal granulomas, who was immediately started on immunosuppressive treatment. Years later, she developed progressive hypoacusis. Magnetic resonance imaging (MRI) revealed an extensive mass in the tympanic cavity extending to the mastoid. A biopsy of the mass was positive for Mycobacterium tuberculosis. Immunosuppressants were weaned and the patient was started on anti-tuberculous therapy with resolution of the complaints and findings. Tuberculous infections are difficult to diagnose and frequently mimic other illnesses, but in our case, we believe that an indolent tuberculous process was present from the beginning and evolved under immunosuppressive therapy. LEARNING POINTS: The differential diagnosis of rhinosinus granulomatous findings includes inflammatory and infectious diseases (for example, tuberculous infections), in addition to neoplasms, cocaine abuse and trauma.A comprehensive differential diagnosis list is essential to mitigate diagnostic errors, especially in patients where auto-immune studies are negative or there is any doubt in the diagnosis.Latent tuberculosis screening should be a concern for physicians treating patients with immunosuppressive therapy, especially in endemic countries.
- Recomendações para o diagnóstico da forma tardia da doença de PompePublication . Brito-Avô, L; Alves, JD; Costa, J; Herrero Valverde, A; Santos, L; Araújo, F; Aguiar, P; Marinho, A; Oliveira, A; Gomes, DINTRODUCTION: Pompe disease is a progressive and debilitating autossomal recessive myopathy due to mutations in lysossomal acid-α-glucosidase. Its late-onset form has a heterogeneous presentation mimicking other neuromuscular diseases, leading to diagnostic challenge. OBJECTIVE: To develop consensus based recommendations for the diagnosis of late-onset Pompe Disease. MATERIAL AND METHODS: Bibliographic review and analysis of an opinion questionnaire applied to a group of specialists with expertise in the diagnosis of several myopathies and lysossomal storage disorders. Discussed in consensus meeting. RECOMMENDATIONS: Patients with a progressive limb-girdle weakness, fatigue, cramps and muscle pain should be evaluated with CK levels, electromyography, dynamic spirometry and muscle biopsy in inconclusive cases. Suspected cases and those in which muscle biopsy could not allow other diagnosis should be screened for lysossomal acid-α-glucosidase deficiency with DBS (dried blood spot). The diagnosis should be confirmed by determination of lysossomal acid-α-glucosidase activity in a second sample and lysossomal acid-α-glucosidase gene sequencing.
- Tocilizumab: is there life beyond anti-TNF blockade?Publication . Alves, JD; Marinho, A; Serra, MAnti-TNF-α therapy has become the most effective biological treatment for rheumatoid arthritis. Despite having changed the prognosis of the disease establishing new targets for treatment strategy, there are several aspects that still remain unmatched. About 30% of the patients with rheumatoid arthritis have a less than satisfactory response to anti-TNF therapy, which has led the way for the pursuit of new targets and approaches to treatment. IL-6 is one of these alternative targets and data from the more recent clinical trials involving tocilizumab (an anti-IL-6 soluble receptor antibody) suggest advantages in relation to some clinical aspects which are not addressed by anti-TNF-α treatment.