Eficacia de la suplementación con L-arginina sobre la respuesta a la quimioterapia neoadyuvante en pacientes con cáncer de mama / Efficacy of L-arginine supplementation on response to neoadjuvant chemotherapy in patients with breast cancer

Introducción El cáncer de mama ocupa el primer lugar en mortalidad por neoplasias en la mujer en México. La quimioterapia neoadyuvante ha reportado una eficacia de alrededor 70%; sin embargo, aquellas pacientes que no responden adecuadamente deben someterse a métodos coadyuvantes que afectan su calidad de vida. El óxido nítrico, brevemente, en concentraciones altas es capaz de tener efectos citotóxicos y tumoricidas, favoreciendo una respuesta adecuada al tratamiento antineoplásico. La L-arginina es precursor del óxido nítrico, por lo que la suplementación puede influir en la síntesis y, por tanto, en su concentración.ObjetivosEvaluar la eficacia de la suplementación de L-arginina sobre la respuesta al tratamiento con quimioterapia neoadyuvante.Materiales y métodosEnsayo clínico de asignación aleatoria que administró un suplemento de 30g de L-arginina en cada ciclo de quimioterapia neoadyuvante. Se determinó la concentración de nitritos antes y después de ingerir el suplemento, así como el tamaño tumoral antes de iniciar el tratamiento y una vez concluido el mismo. Se realizó una prueba chi-cuadrado para evaluar la asociación entre la suplementación y una respuesta adecuada al tratamiento; los nitritos plasmáticos fueron evaluados mediante pruebas t-student.ResultadosSe evaluaron 45 pacientes. Veintiuno tuvieron una respuesta adecuada al tratamiento oncológico; sin embargo, no se encontró una asociación significativa entre la suplementación y dicha respuesta. La concentración de nitritos plasmáticos aumentó de manera significativa (p<0,05) en el grupo que recibió el suplemento con L-arginina.Conclusiones(..) (AU)

Background Breast cancer is the first cause of mortality from malignant neoplasms among women in Mexico. Neoadjuvant chemotherapy has a reported efficacy of approximately 70%; however, patients with inadequate response must undergo additional coadjuvant methods that negatively affect their quality of life. High concentrations of nitric oxide have shown cytotoxic and tumoricidal effects, thus favoring an adequate response to antineoplastic treatment. L-arginine is a nitric oxide precursor and therefore supplementation with this substance can augment nitric oxide synthesis and consequently its plasma concentration.ObjectivesTo evaluate the efficacy of L-arginine supplementation in response to neoadjuvant chemotherapeutic treatment.Materials and methodsWe conducted a randomized clinical trial in which 30g of L-arginine was administered in each neoadjuvant chemotherapy cycle. Plasma nitrite concentrations were determined before and after supplementation, as well as tumoral size before the start of antineoplastic treatment and after its completion. A chi-square test was performed to evaluate the association between the supplementation and adequate treatment response; plasma nitrites were evaluated by performing Student's T-tests.ResultsForty-five patients were assessed, of whom 21 had an adequate response to antineoplastic treatment. No statistically significant association was found between supplementation and adequate response. Nitrite concentrations in plasma were significantly increased (p<0.05) in patients receiving the supplement than in those who receiving placebo.Conclusions(..) (AU)

Antibacterial properties of some plants used in Mexican traditional medicine for the treatment of gastrointestinal disorders.

Antibacterial properties of aqueous and methanolic extracts of 26 medicinal plants used in Mexico to treat gastrointestinal disorders were tested against eight different species of enteropathogens: two Escherichia coli species; two Shigella sonnei species; two Shigella flexneri species; and two Salmonella sp. species. The results showed that all crude extracts exhibited antibacterial activity, at least against one of the microorganisms tested, at concentrations of 8 mg/mL or lower. The extracts from Caesalpinia pulcherria, Chiranthodendron pentadactylon, Cocos nucifera, Geranium mexicanum (aerial parts and roots), Hippocratea excelsa, and Punica granatum possessed strong antibacterial activity against most of the pathogens tested. In general, methanolic extracts were more active than aqueous extracts. Their activity was higher than chloramphenicol but did not exceed that of trimethoprim. Shigella sonnei species showed the highest susceptibility to both extracts. This is the first evaluation of these plants against bacterial pathogen isolates, which cause diarrhea and dysentery in Mexican population.

[Changes in the vasoconstrictor action of noradrenaline and in its receptor-binding kinetics induced by sex hormones]. / Cambios en la acción vasoconstrictora de la noradrenalina y en su cinética de unión a receptores, inducidos por hormonas sexuales.

The role of testosterone/17 B estradiol ratios (T/E), on the vasoconstrictor effect of norepinephrine (NE), were studied in strips of carotid arteries from dogs. T/E of 0.1 (T = 1 nM/E = 10 nM) shifted the concentration/effect (C-E) curve of NE to the right. T/E of 10 (T = 10 nM/E = 1 nM) deviated it to the left. T (1 nM and 10 nM) shifted the C-E curve of NE to the right; E = 1 nM did not modify it; E = 10 nM, shifted it to the left. In microsomal fraction of carotid arteries, adrenergic receptors were characterized with 3H-NE binding, and the role of T/E ratios also studied. Under the influence of T/E ratio of 10, the agonist affinity (Ka), was increased from 100 nM-1 to 128 nM-1, the receptors density (Bmax), increased from 78.3 nM to 148 nM. E (1 nM) reduced Ka to 88 nM-1, T did not change any of these parameters. In conclusion, T/E ratios of 10, as in male, may enhance the vasoconstrictor activity of NE, increasing Ka and Bmax of adrenergic receptors.