Browsing by Author "Duarte, N."
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- Antifungal and multidrug resistance modulatory effects of diterpenic and phenolic compoundsPublication . Ferreira, M. J. U.; Duarte, N.; Kolaczkowski, M.; Michalak, K.
- Antiproliferative activity of ent-abietane lactones against resistant human cancer cell linesPublication . Duarte, N.; Loge, H.; Ferreira, M. J. U.
- Blood cell membrane fluidity and intracellular Ca2+ changes in antiretroviral-naïve and -treated HIV-1-infected patientsPublication . Santos, Nuno C.; Martins e Silva, J.; Freitas, Teresa; Doroana, M.; Duarte, N.; Tavares, L.; Antunes, F.; Saldanha, CarlotaWe previously showed that lymphocytes and erythrocytes of HIV-1–infected patients, prior to antiretroviral therapy, presented significant changes in intracellular calcium concentration ([Ca2+]int) and membrane fluidity. The present study evaluates the same parameters after response to highly active antiretroviral therapy (HAART). Blood samples were collected from patients prior to and after antiretroviral therapy, and from control subjects. Membrane fluidity and [Ca2+]int were assessed by fluorescence spectroscopy measurements, using three different probes: TMA-DPH and DPH for membrane fluidity, and fura-2 for Ca2+. When compared with the control group, both untreated and treated patients presented increased lymphocyte [Ca2+]int and decreased lymphocyte membrane fluidity, without significant differences between the two groups of patients. On the contrary, the therapy reversed the membrane fluidity variations observed in erythrocytes. The decreased erythrocyte [Ca2+]int of untreated patients was not reversed by HAART. AIDS patients present changes in lymphocyte (mostly noninfected) and erythrocyte properties, partially reversed by HAART, consistent with a process of facilitated propagation of the infection to new cells, stimulation of virion production, and maintenance of a reservoir of erythrocyte-bound infectious virus. These observations can be related with the action of the HIV Nef protein in the cell’s proteins and lipid composition, as well as with the recently observed cell infection by HIV-1 via endocytosis.
- Diterpenic compounds as antineoplasic agents in classical and atypical multidrug resistant cancer cellsPublication . Duarte, N.; Lage, H.; Ferreira, M. J. U.
- Effects of piceatannol derivatives in the antiproliferative activity of the anticancer-drug doxorubicine and on apoptosis induction in MDR cancer cell linesPublication . Ferreira, M. J. U.; Duarte, N.; Gyemant, N.; Varga, A.; Molnar, J.
- INFLUENCE OF THE MULTIDRUG TRANSPORTER INHIBITORS ON THE ACTIVITY OF KV1.3 VOLTAGE-GATED POTASSIUM CHANNELSPublication . Teisseyre, A.; Duarte, N.; Ferreira, M-J. U.; Michalak, K.Using the whole-cell patch-clamp technique, the influence of selected multidrug resistance modulators, both plant-derived compounds and derivatives on the activity of voltage-gated potassium channels Kv1.3 was investigated. Twelve compounds with phenolic and terpenic structures were tested: the stilbenes piceatannol (1) and its tetramethoxy (2) and tetracetoxy (3) derivatives, the flavonoids naringenin (4) and its methylated derivatives: naringenin-4',7-dimethylether (5) and naringenin-7-methylether (6), and aromadendrin (7), the coumarins esculetin (13) and scopoletin (9) and ent-abietane diterpenes, helioscopinolide B (10) and its 3 beta-acetoxy derivative (11) and helioscopinolide E (12). The studies were performed on a model system with Kv1.3 channels endogenously expressed in human T lymphocytes. Obtained data provide evidence that compounds 2, 5 and 6 applied at 30 mu M inhibited the amplitude of recorded currents to 31%, 4% and 29% of its control value, respectively. On the other hand, compounds 3, 4, 7-12 (at 30 mu M) and compound 1 (at 40 mu M) did not affect significantly the channel activity. These results indicate that some methoxy-derivatives of the tested compounds are effective inhibitors of Kv1.3 channels. Since the inhibition of Kv1.3 channels may inhibit the proliferation of prostate, breast and colon cancer cells expressing these channels, the channel inhibitors may exert an anti proliferative action. This action combined with a simultaneous modulation of the multidrug resistance may be significant for a potential application of these compounds in cancer chemotherapy.. - Polish Ministry of Research and University Education [N 301 2549 33]; Science and Technology Foundation (FCT), Portugal. - The Authors would like to express best thanks to the colleague from the Biophysics Department of Wroclaw Medical University - Dr. Andrzej Pola, for a kind help in providing blood samples for isolation of T lymphocytes. This work was supported by the Polish Ministry of Research and University Education (Ministerstwo Nauki i Szkolnictwa Wyzszego) Grant no N 301 2549 33 (A.T. and K.M.) and by the Science and Technology Foundation (FCT), Portugal (N.D. and M-J.U.F.).
- Inhibition of P-glycoprotein activity by curcubitane-type triterpenes and their interaction with doxorubicine on resistant cancer cellsPublication . Ramalhete, C.; Duarte, N.; Capucha, V; Molnar, J.; Mulhovo, S.; Rosario, V; Ferreira, M. J. U.
- Search for antimalarial compounds from Pycnanthus angolensisPublication . Ramalhete, C.; Abrantes, M.; Mil-Homens, T.; Duarte, N.; Lopes, D.; Cravo, F.; Madureira, M. C.; Ascenso, J.; Ferreira, M. J. U.
- Search for P-glycoprotein modulators and apoptosis inducers on cancer cells among ergostane and stigmastane steroidsPublication . Duarte, N.; Ramalhete, C.; Gyemant, N.; Varga, A.; Molnar, J.; Ferreira, M. J. U.
- Synergistic effects between macrocyclic cliterpenes and doxorubicine on resistant cancer cellsPublication . Duarte, N.; Jardanhazy, A.; Ramalhete, C.; Molnar, J.; Ferreira, M. J. U.