Browsing by Author "Ribeiro, M"
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- Bioenergetic dysfunction in Huntington's disease human cybridsPublication . Ferreira, IL; Cunha-Oliveira, T; Nascimento, MV; Ribeiro, M; Proença, MT; Januário, C; Oliveira, CR; Rego, ACIn this work we studied the mitochondrial-associated metabolic pathways in Huntington's disease (HD) versus control (CTR) cybrids, a cell model in which the contribution of mitochondrial defects from patients is isolated. HD cybrids exhibited an interesting increase in ATP levels, when compared to CTR cybrids. Concomitantly, we observed increased glycolytic rate in HD cybrids, as revealed by increased lactate/pyruvate ratio, which was reverted after inhibition of glycolysis. A decrease in glucose-6-phosphate dehydrogenase activity in HD cybrids further indicated decreased rate of the pentose-phosphate pathway. ATP levels of HD cybrids were significantly decreased under glycolysis inhibition, which was accompanied by a decrease in phosphocreatine. Nevertheless, pyruvate supplementation could not recover HD cybrids' ATP or phosphocreatine levels, suggesting a dysfunction in mitochondrial use of that substrate. Oligomycin also caused a decrease in ATP levels, suggesting a partial support of ATP generation by the mitochondria. Nevertheless, mitochondrial NADH/NAD(t) levels were decreased in HD cybrids, which was correlated with a decrease in pyruvate dehydrogenase activity and protein expression, suggesting decreased tricarboxylic acid cycle (TCA) input from glycolysis. Interestingly, the activity of alpha-ketoglutarate dehydrogenase, a critical enzyme complex that links the TCA to amino acid synthesis and degradation, was increased in HD cybrids. In accordance, mitochondrial levels of glutamate were increased and alanine was decreased, whereas aspartate and glutamine levels were unchanged in HD cybrids. Conversely, malate dehydrogenase activity from total cell extracts was unchanged in HD cybrids. Our results suggest that inherent dysfunction of mitochondria from HD patients affects cellular bioenergetics in an otherwise functional nuclear background.
- Circumferential vascular strain rate to estimate vascular load in aortic stenosis: a speckle tracking echocardiography studyPublication . Teixeira, R; Monteiro, R; Baptista, R; Barbosa, A; Leite, L; Ribeiro, M; Martins, R; Cardim, N; Gonçalves, LEvaluation of vascular mechanics through two-dimensional speckle-tracking (2D-ST) echocardiography is a feasible and accurate approach for assessing vascular stiffening. Degenerative aortic stenosis (AS) is currently considered a systemic vascular disease where rigidity of arterial walls increases. To assess the circumferential ascending aorta strain rate (CAASR) in thoracic aortas of patients with AS, applying 2D-ST technology. 45 patients with indexed aortic valve areas (iAVA) ≤0.85 cm(2)/m(2) were studied. Global CAASR served to assess vascular deformation. Clinical, echocardiographic, and non-invasive hemodynamic data were collected. A follow up (955 days) was also performed. Average age of the cohort was 76. ± 10.3 years, with gender balance. Mean iAVA was 0.43 ± 0.15 cm(2)/m(2). Waveforms adequate for determining CAASR were found in 246 (91 %) of the 270 aortic segments evaluated, for a mean global CAASR of 0.74 ± 0.26 s(-1). Both intra- and inter-observer variability of global CAASR were deemed appropriate. CAASR correlated significantly with age (r = -0.49, p < 0.01), the stiffness index (r = -0.59, p < 0.01), systemic arterial compliance and total vascular resistance. There was a significant positive correlation between CAASR, body surface area (BSA), iAVA, and a negative relationship with valvulo-arterial impedance and E/e' ratio (r = -0.37, p = 0.01). The stiffness index was (β = -0.41, p < 0.01) independently associated with CAASR, in a model adjusted for age, BSA, iAVA and E/e'. Patients with a baseline CAASR ≤0.66 s(-1) had a worse long-term outcome (survival 52.4 vs. 83.3 %, Log Rank p = 0.04). CAASR is a promising echocardiographic tool for studying the vascular loading component of patients with AS.
- Evaluation of the anti-inflammatory, anti-catabolic and pro-anabolic effects of E-caryophyllene, myrcene and limonene in a cell model of osteoarthritisPublication . Rufino, AT; Ribeiro, M; Sousa, C; Judas, F; Salgueiro, L; Cavaleiro, C; Mendes, AFOsteoarthritis is a progressive joint disease and a major cause of disability for which no curative therapies are yet available. To identify compounds with potential anti-osteoarthritic properties, in this study, we screened one sesquiterpene, E-caryophyllene, and two monoterpenes, myrcene and limonene, hydrocarbon compounds for anti-inflammatory, anti-catabolic and pro-anabolic activities in human chondrocytes. At non-cytotoxic concentrations, myrcene and limonene inhibited IL-1β-induced nitric oxide production (IC50=37.3μg/ml and 85.3µg/ml, respectively), but E-caryophyllene was inactive. Myrcene, and limonene to a lesser extent, also decreased IL-1β-induced NF-κB, JNK and p38 activation and the expression of inflammatory (iNOS) and catabolic (MMP-1 and MMP-13) genes, while increasing the expression of anti-catabolic genes (TIMP-1 and -3 by myrcene and TIMP-1 by limonene). Limonene increased ERK1/2 activation by 30%, while myrcene decreased it by 26%, relative to IL-1β-treated cells. None of the compounds tested was able to increase the expression of cartilage matrix-specific genes (collagen II and aggrecan), but both compounds prevented the increased expression of the non-cartilage specific, collagen I, induced by IL-1β. These data show that myrcene has significant anti-inflammatory and anti-catabolic effects in human chondrocytes and, thus, its ability to halt or, at least, slow down cartilage destruction and osteoarthritis progression warrants further investigation.
- Hyperglycemia and Hyperinsulinemia-Like Conditions Independently Induce Inflammatory Responses in Human ChondrocytesPublication . Rufino, A; Ribeiro, M; Pinto Ferreira, J; Judas, F; Mendes, ATo elucidate the mechanisms by which type 2 Diabetes Mellitus (DM2) constitutes a risk factor for the development and progression of osteoarthritis (OA), this work determined whether high glucose and/or high insulin, the hallmarks of DM2, are capable of activating the transcription factor, Nuclear Factor-κB (NF-κB), which plays a critical role in OA by inducing the expression of pro-inflammatory and catabolic genes. For this, we analyzed NF-κB activation by measuring the nuclear levels of p65 by western blot. As readouts of NF-κB activity, Interleukin-1β, Tumor Necrosis Factor-α, and inducible nitric oxide synthase (iNOS) expression were analyzed by real time RT-PCR and western blot. Culture of the human chondrocytic cell line, C28-I2, in high glucose (30 mM) increased nuclear NF-κB p65 levels in a time-dependent manner, relative to cells cultured in medium containing 10 mM glucose (regular culture medium). High glucose-induced NF-κB activation was inhibited by co-treatment with its specific inhibitor, Bay 11-7082, 5 µM. Culture of primary human chondrocytes under high glucose for 24 h increased IL-1β and TNF-α mRNA levels by 97% (p = 0.0066) and 85% (p = 0.0045), respectively, while iNOS mRNA and protein levels and NO production increased by 61% (p = 0.0017), 148% (p = 0.0089), and 70% (p = 0.049), respectively, relative to chondrocytes maintained in 10 mM glucose. Treatment of chondrocytic cells with 100 nM insulin was also sufficient to increase nuclear NF-κB p65 levels, independently of the glucose concentration in the culture medium. This study shows that hyperglycemia and hyperinsulinemia are independently sufficient to induce inflammatory responses in human chondrocytes, namely by activating NF-κB. This can be a relevant mechanism by which DM type 2 and other conditions associated with impaired glucose and insulin homeostasis, like obesity and the metabolic syndrome, contribute to the development and progression of OA.
- Primary Bilateral Thalamic Astrocytoma Presenting With Head Tremor, Ataxia, and DementiaPublication . Machado, A; Ribeiro, M; Rodrigues, M; Ferreira, C; Almeida, R; Santana, I; Castro, L; Carpenter, S
- Quercetin in Cancer Treatment, Alone or in Combination with Conventional Therapeutics?Publication . Brito, AF; Ribeiro, M; Abrantes, AM; Pires, AS; Teixo, RJ; Tralhão, JG; Botelho, MFCancer is a problem of global importance, since the incidence is increasing worldwide and therapeutic options are generally limited. Thus, it becomes imperative to find new therapeutic targets as well as new molecules with therapeutic potential for tumors. Flavonoids are polyphenolic compounds that may be potential therapeutic agents. Several studies have shown that these compounds have a higher anticancer potential. Among the flavonoids in the human diet, quercetin is one of the most important. In the last decades, several anticancer properties of quercetin have been described, such as cell signaling, pro-apoptotic, anti-proliferative and anti-oxidant effects, growth suppression. In fact, it is now well known that quercetin has diverse biological effects, inhibiting multiple enzymes involved in cell proliferation, as well as, in signal transduction pathways. On the other hand, there are also studies reporting potential synergistic effects when combined quercetin with chemotherapeutic agents or radiotherapy. In fact, several studies which aim to explore the anticancer potential of these combined treatments have already been published, the majority with promising results. Actually it is well known that quercetin can act on the chemosensitization and radiosensitization but also as chemoprotective and radioprotective, protecting normal cells of the side effects that results from chemotherapy and radiotherapy, which obviously provides notable advantages in their use in anticancer treatment. Thus, all these data indicate that quercetin may have a key role in anticancer treatment. In this context, this review is focused on the relationship between flavonoids and cancer, with special emphasis on the role of quercetin.