Leandro Augusto Barbosa

Bioethics and nutrition in adult patients with cancer in palliative care

Cancer constitutes a major group of chronic diseases and is the second leading cause of death in the developed countries. Palliative care proposes to offer comprehensive support to control symptoms and improve quality of life for patients and their families. Nutrition is an important tool in palliative care, helping patients with their physical, psychological, and social issues and promoting comfort and quality of life. However, in the context of palliative care, nutritional support rarely achieves its role of fully recovering and assuring nutritional status. At this point, the nutritionist must consider the individual patients needs, preferences, and eating habits, which are essential both for controlling symptoms and assuring satisfaction and comfort. The impossibility of conventionally applying established management and the development of a new perception of the patient often raise dilemmas for professional nutritionists.

21-Benzylidene Digoxin: A Proapoptotic Cardenolide of Cancer Cells That Up-Regulates Na,K-ATPase and Epithelial Tight Junctions

Cardiotonic steroids are used to treat heart failure and arrhythmia and have promising anticancer effects. The prototypic cardiotonic steroid ouabain may also be a hormone that modulates epithelial cell adhesion. Cardiotonic steroids consist of a steroid nucleus and a lactone ring, and their biological effects depend on the binding to their receptor, Na,K-ATPase, through which, they inhibit Na+ and K+ ion transport and activate of several intracellular signaling pathways. In this study, we added a styrene group to the lactone ring of the cardiotonic steroid digoxin, to obtain 21-benzylidene digoxin (21-BD), and investigated the effects of this synthetic cardiotonic steroid in different cell models. Molecular modeling indicates that 21-BD binds to its target Na,K-ATPase with low affinity, adopting a different pharmacophoric conformation when bound to its receptor than digoxin. Accordingly, 21-DB, at relatively high µM amounts inhibits the activity of Na,K-ATPase α1, but not α2 and α3 isoforms. In addition, 21-BD targets other proteins outside the Na,K-ATPase, inhibiting the multidrug exporter Pdr5p. When used on whole cells at low µM concentrations, 21-BD produces several effects, including: 1) up-regulation of Na,K-ATPase expression and activity in HeLa and RKO cancer cells, which is not found for digoxin, 2) cell specific changes in cell viability, reducing it in HeLa and RKO cancer cells, but increasing it in normal epithelial MDCK cells, which is different from the response to digoxin, and 3) changes in cell-cell interaction, altering the molecular composition of tight junctions and elevating transepithelial electrical resistance of MDCK monolayers, an effect previously found for ouabain. These results indicate that modification of the lactone ring of digoxin provides new properties to the compound, and shows that the structural change introduced could be used for the design of cardiotonic steroid with novel functions.

Ouabain-Induced Alterations of the Apical Junctional Complex Involve α1 and β1 Na,K-ATPase Downregulation and ERK1/2 Activation Independent of Caveolae in Colorectal Cancer Cells

Studies have reported that Na,K-ATPase interacts with E-cadherin to stabilize (AJs) and regulate the expression of claudins, the main proteins present in the tight junction (TJ) in epithelial cells containing caveolae. However, the role of this ATPase in the regulation of the AJ and TJ proteins in colorectal cancer cells as well as the molecular events underlying this event in a caveolae-independent system remain undefined. In the present study, we used ouabain, a classic drug known to inhibit Na,K-ATPase, and Caco-2 cells, which are a well-established human colorectal cancer model that does not exhibit caveolae. We demonstrated that ouabain treatment resulted in a reduction of the β1 Na,K-ATPase protein and cell redistribution of the AJ proteins E-cadherin and β-catenin, as well as the α1 Na,K-ATPase subunit. Furthermore, ouabain increased claudin-3 protein levels, impaired the TJ barrier function and increased cell viability and proliferation during the early stages of treatment. Additionally, the observed ouabain-induced events were dependent on the activation of ERK1/2 signaling; but in contrast to previous studies, this signaling cascade was caveolae-independent. In conclusion, our findings strongly suggest that α1 and β1 Na,K-ATPase downregulation and ERK1/2 activation induced by ouabain are interlinked events that play an important role during cell–cell adhesion loss, which is an important step during the tumor progression of colorectal carcinomas.

Design and Synthesis of New Chacones Substituted with Azide/Triazole Groups and Analysis of Their Cytotoxicity Towards HeLa Cells

A series of new chalcones substituted with azide/triazole groups were designed and synthesized, and their cytotoxic activity was evaluated in vitro against the HeLa cell line. O-Alkylation, Claisen-Schmidt condensation and Cu(I)-catalyzed cycloaddition of azides with terminal alkynes were applied in key steps. Fifteen compounds were tested against HeLa cells. Compound 8c was the most active molecule, with an IC50 value of 13.03 µM, similar to the value of cisplatin (7.37 µM).

Efficacy of methotrexate-loaded poly(ε-caprolactone) implants in Ehrlich solid tumor-bearing mice.

Abstract Context: Methotrexate (MTX) is used in the treatment of malignancies; however, its clinical application is limited by its toxic dose-related side effects. An alternative to overcome the toxicity of the MTX in healthy tissues is the design of an implantable device capable of controlling the delivery of this drug for an extended period within the tumor site. Objective: To develop methotrexate-loaded poly(ε-caprolactone) implants (MTX PCL implants) and to demonstrate their efficacy as local drug delivery systems capable of inhibiting Ehrlich solid tumor bearing mice. Materials and methods: MTX PCL implants were produced by the melt-molding technique and were characterized by FTIR, WAXS, DSC and SEM. The in vitro and in vivo release of MTX from the PCL implants was also evaluated. The efficacy of implants in inhibiting tumor cells in culture and the solid tumor in a murine model was revealed. Results and discussion: The chemical and morphological integrity of the drug was preserved into the polymeric matrix. The in vitro and in vivo release processes of the MTX from the PCL implants were modulated by diffusion. MTX diffused from the implants revealed an antiproliferative effect on tumor cells. Finally, MTX controlled and sustained released from the polymeric implants efficiently reduced 42.7% of the solid tumor in mice paw. Conclusion: These implantable devices represented a contribution to improve the efficacy and safety of chemotherapy treatments, promoting long-term local drug accumulation in the targeted site.

Effects of Iron Overload on the Activity of Na,K-ATPase and Lipid Profile of the Human Erythrocyte Membrane

Iron is an essential chemical element for human life. However, in some pathological conditions, such as hereditary hemochromatosis type 1 (HH1), iron overload induces the production of reactive oxygen species that may lead to lipid peroxidation and a change in the plasma-membrane lipid profile. In this study, we investigated whether iron overload interferes with the Na,K-ATPase activity of the plasma membrane by studying erythrocytes that were obtained from the whole blood of patients suffering from iron overload. Additionally, we treated erythrocytes of normal subjects with 0.8 mM H2O2 and 1 μM FeCl3 for 24 h. We then analyzed the lipid profile, lipid peroxidation and Na,K-ATPase activity of plasma membranes derived from these cells. Iron overload was more frequent in men (87.5%) than in women and was associated with an increase (446%) in lipid peroxidation, as indicated by the amount of the thiobarbituric acid reactive substances (TBARS) and an increase (327%) in the Na,K-ATPase activity in the plasma membrane of erythrocytes. Erythrocytes treated with 1 μM FeCl3 for 24 h showed an increase (132%) in the Na,K-ATPase activity but no change in the TBARS levels. Iron treatment also decreased the cholesterol and phospholipid content of the erythrocyte membranes and similar decreases were observed in iron overload patients. In contrast, erythrocytes treated with 0.8 mM H2O2 for 24 h showed no change in the measured parameters. These results indicate that erythrocytes from patients with iron overload exhibit higher Na,K-ATPase activity compared with normal subjects and that this effect is specifically associated with altered iron levels.

Semente de linhaça e o efeito de seus compostos sobre as células mamárias

O câncer de mama e uma doenca que afeta principalmente as mulheres e segundo as estatisticas esta vem aumentando com certa frequencia nos paises ocidentais, e isto tem preocupado a comunidade cientifica. Esta doenca esta associada a diversos fatores de risco, sendo a dieta um fator que tem demonstrado relacao com a promocao de câncer de mama. Uma alimentacao rica em substância funcional tem sido alvo de atencao, pois os fitoestrogenos tem mostrado atraves de estudos experimentais, propriedades beneficas a saude, e parece contribuir para a reducao do risco de câncer de mama. Alimentos como a semente de linhaca tem sido objeto de estudo, ja que contem substâncias consideradas como quimioprotetora e sua estrutura quimica assemelha-se ao estrogenio humano e compete com este pelo seu sitio de ligacao. De acordo com os estudos experimentais, realizados com animais e humanos, a semente de linhaca e rica em lignana e outros componentes, que apresentaram ter efeito fracamente estrogenico e antiestrogenico, mostrando exercer influencia na diminuicao do risco de câncer de mama.

Administração de antibióticos por via subcutânea: uma revisão integrativa da literatura

OBJETIVO: Caracterizar los articulos cientificos relacionados al uso de antibioticos por via subcutanea en pacientes con dificil acceso venoso en cuidados paliativos en cuanto a la tolerancia local y eficacia terapeutica. METODOS: Revision integrativa de la literatura realizada en las bases de datos LILACS, CINAHL, PUBMED, EMBASE y Biblioteca Cochrane, utilizandose como referencial teorico la Practica Basada en Evidencias. RESULTADOS: Fueron seleccionados 17 articulos con diez antibioticos diferentes, siendo la Ceftriaxona, el antibiotico mas estudiado. Se constato la eficacia terapeutica con base en los parametros farmacocineticos y clinicos. La tolerancia local estuvo asociada a la mayor dilucion de los antibioticos. Con administracion de aminoglicosideos, se observaron lesiones graves y necrosis tecidual. La baja tolerancia refuerza la restriccion de uso apenas para esa clase de antibioticos. CONCLUSION: Las previsiones de eficacia terapeutica y la buena tolerancia sugieren una posibilidad a ser considerada cuando se desea una via de administracion parenteral alternativa, sin embargo se recomienda cautela, puesto que ninguno de los estudios evaluo a pacientes en cuidados paliativos.OBJECTIVE: To characterize scientific articles related to the use of antibiotics by the subcutaneous route in patients with difficult venous access in palliative care, regarding local tolerance and therapeutic efficacy. METHODS: Integrative literature review conducted in the databases of LILACS, CINAHL, PubMED, EMBASE and the Cochrane Library, using Evidence-Based Practice as a theoretical framework. RESULTS: Seventeen articles were selected with ten different antibiotics, with ceftriaxone being the most studied antibiotic. Therapeutic efficacy was observed based on pharmacokinetic and clinical parameters. The local tolerance was associated with greater dilution of antibiotics. With administration of aminoglycosides, serious injuries and tissue necrosis were observed. A low tolerance reinforced the restriction of use only to this class of antibiotics. CONCLUSION: The predictions of therapeutic efficacy and good tolerance suggest a possibility to be considered when there is need of an alternative parenteral route of administration, but caution is advised, since none of the studies evaluated patients in palliative care.

Differences of lipid membrane modulation and oxidative stress by digoxin and 21-benzylidene digoxin

&NA; Cardiotonic steroids (CTS) are compounds which bind to the Na,K‐ATPase, leading to its inhibition and in some cases initiating signaling cascades. Long utilized as a treatment for congestive heart disease, CTS have more recently been observed to inhibit proliferation and cause apoptosis in several cancer cell lines. A synthetic derivative of the CTS digoxin, called 21‐benzylidene digoxin (21‐BD), activates the Na,K‐ATPase rather than cause its inhibition, as its parent compound does. Here, the mechanism behind the unique effects of 21‐BD are further explored. In HeLa cancer cells, low (5 &mgr;M) and high (50 &mgr;M) doses of 21‐BD activated and inhibited the Na,K‐ATPase, respectively, without altering the membrane expression of the Na,K‐ATPase. While digoxin did not affect HeLa membrane cholesterol or phospholipid content, 50 &mgr;M 21‐BD increased both lipids via a mechanism reliant on an intact cell. Afterwards, the direct action of 21‐BD was evaluated on erythrocyte membranes; however, no effect was observed. As CTS may generate reactive oxygen species (ROS) which can affect plasma membrane fluidity and therefore Na,K‐ATPase activity, several markers involved in ROS generation were analyzed such as, lipid peroxidation (TBARS), reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD). GSH content and catalase activity were unaffected by digoxin or 21‐BD. Surprisingly, TBARS and SOD activity was decreased with digoxin and with 50 &mgr;M 21‐BD. Thus, 21‐BD and digoxin altered components involved in ROS generation and inhibition in a similar fashion. This study suggests alterations to the Na,K‐ATPase and membrane lipids by 21‐BD is not reliant on ROS generation.

Could Na,K-ATPase play a role in potassium leakage from irradiated erythrocytes?

BACKGROUND In developing countries, the access to red blood cell (RBC) irradiators is restricted. Thus, it is a common practice in blood banks to stock irradiated RBC units until they expire. The aim of this work is to elucidate the involvement of Na,K-ATPase in potassium leakage from prophylactically irradiated RBCs. METHODS Whole blood was collected from healthy donors, and blood concentrates were irradiated with 25Gy of γ-radiation within 24h of collection. At days 3, 5, 7, 9, 11, 14 and 28 post-irradiation, fractions were removed and centrifuged and Na,K-ATPase activity from ghost membranes was determined. RESULTS The inhibition of Na,K-ATPase activity in RBCs reached 12.6% by day 7 of storage and up to 50% by day 14 of storage. The addition of vitamin C prevented the irradiation-induced loss of Na,K-ATPase activity. The irradiation of RBCs provoked an increase in potassium plasma levels and a decrease in sodium plasma levels. The incubation of RBCs with ouabain did not change the sodium or potassium levels in the plasma, and the addition of vitamin C only partially prevented a decrease in sodium levels caused by irradiation. CONCLUSION Because the inhibition of Na,K-ATPase by ouabain did not cause potassium accumulation in the plasma, we conclude that the irradiation-induced inhibition of the pump is not a key factor driving this effect.