Liliana Favari

Parameters for the adsorption of thallium ions by activated charcoal and Prussian blue.

Activated charcoal and Prussian blue are effective antidotes in acute thallium (T1+) intoxication in rats. They act by trapping any metal present in or secreted into the gut by the gastro-intestinal epithelium. It was therefore of interest to determine the parameters of the Langmuir adsorption isotherms of T1+ ions for these two adsorbents. The data from equilibration experiments were analyzed by direct least-squares fitting to a hyperbola and with Langmuirs equation to give the following results: Activated charcoal: K1(-1) = 192 micrograms ml-1, K2 = 124 mg g-1 Prussian Blue: K1(-1) = 130 micrograms ml-1, K2 = 72 mg g-1. These high values provide in vitro confirmation of their in vivo antidotal efficacy and show that activated charcoal can replace Prussian blue when this latter drug is unobtainable.

Effects of leukotriene synthesis inhibition on acute liver damage induced by carbon tetrachloride.

Administration of the leukotriene synthesis inhibitors nordihydroguaiaretic acid (NDHGA, 30 mg/kg), caffeic acid (20 mg/kg) or nafazatrom (100 mg/kg) and of the phosphodiesterase inhibitor and free radical trapper dipyridamole (10 mg/kg) prevented the alterations in enzyme activity displayed by acute CCl4 administration. The effect was less evident in preventing hepatic glycogen depletion or lipid peroxidation. A synergistic protective effect between dipyridamole and NDHGA or caffeic acid was observed. In conclusion, the present results show that acute hepatic damage induced by CCl4 can be partially prevented by leukotriene synthesis inhibitors and the protection is enhanced with the simultaneous use of phosphodiesterase inhibitors.

Acute thallium intoxication: kinetic study of the relative efficacy of several antidotal treatments in rats

Rats were administered a sublethal dose of thallium (12.35 mg/kg as aqueous thallous sulfate, Tl2SO4, equivalent to 10 mg Tl+/kg per os) on day 0. Urine and feces were collected separately every day for 8 days and analyzed by atomic absorption spectroscopy. Based on information in the literature, five antidotal treatments (dithizone, activated charcoal, furosemide, Prussian Blue, and a combination of Prussian Blue and furosemide) were compared with controls for their efficacy in reducing the total thallium body load. In the control group (C, n=10) of an approcimate administered dose of 2 mg, after 8 days 411 μg (21%) had been eliminated in the urine and 641 μg (32%) in the feces, making a total of 1,052 μg (53%). In the treated groups the effects were very significant and in accord with the mode of action of the antidotes: furosemide (a diuretic) only enhanced urinary elimination; activated charcoal and Prussian Blue (unabsorbed adsorbents) only increased fecal elimination; dithizone increased only urinary elimination, whereas combined treatment with Prussian Blue and furosemide increased elimination by both routes. At the end of 8 days the control group had only eliminated 53% of the dose; this was increased to 99% by dithizone, 93% by activated charcoal, 64% by furosemide, 82% by Prussian Blue and 92% by combining furosemide and Prussian Blue. In view of the inherent toxicity of dithizone, it is suggested that treatment with a combination of Prussian Blue-furosemide or with activated charcoal should be adequate. Although the excretion data (urinary, fecal, and total) could not be fitted to any simple kinetic model, the continued fecal excretion over 8 days strongly suggests active excretion by the GI tract in accord with earlier observations. This provides the rationale for the use of adsorbents in the GI tract. Of eight rats challenged with a high dose of 20 mg/kg Tl+ and treated with Prussian Blue and furosemide, only one survived; its elimination rates were followed for 22 days, over which first-order kinetics were observed (ke=0.070 day−1) and 81% of the dose was eliminated.

Liver Histopatology, Lipidperoxidation and Somatic Indices of Fulica americana in Xochimilco (Urban) and Tecocomulco (Rural) Wetlands in the Mexico Basin

Los humedales son cuerpos de agua muy productivos y son refugio para aves migratorias; sin embargo, continuamente reciben contaminantes que ejercen danos en los organismos acuaticos. El objetivo del trabajo fue evaluar el estado de salud de Fulica americana mediante biomarcadores histopatologicos, de estres oxidativo, e indices somaticos en dos humedales de la Cuenca de Mexico, para evaluar el efecto de las condiciones del habitat en la salud de las aves. Se obtuvieron ejemplares en los humedales, Xochimilco (X) y Tecocomulco (T) en diferentes periodos de un ano. Se determino su edad, se evisceraron y pesaron, se obtuvieron porciones del higado para el analisis histologico y para la cuantificacion del nivel de lipoperoxidacion (LPO). Se analizo la calidad del agua de X y T. Se realizo la tecnica histologica de inclusion en parafina y la tincion Hematoxilina-Eosina. El mayor deterioro de la calidad del agua se observo en X. Se encontro infiltracion leucocitaria (IN) y vasocongestion (VA) en tres grados. En T se observo la mayor prevalencia de ejemplares con danos combinados, en particular en las hembras; mientras que en X se presento un mayor porcentaje de organismos con IN. La LPO mas alta se observo durante el invierno en T lo que pudiera estar relacionado con el arribo de aves migratorias y la caceria; mientras que en X la mayor LPO estuvo relacionada con la reproduccion. La mayor masa corporal eviscerada se presento en los machos de T y la menor en las hembras de X. En todas las gallaretas los indices hepatosomaticos maximos se alcanzaron en otono y los minimos en primavera. F. americana puede ser utilizada como centinela debido a que presento respuestas diferenciadas en los indices somaticos y en los biomarcadores histopatologicos y de estres oxidativo en las distintas localidades, sexo y epocas del ano.

Biological Responses of the American Coot (Fulica americana), in wetlands with contrasting environmental conditions (Basin of México)

ABSTRACT Wetland ecosystems are subject to severe impacts (physical and chemical) and to the input of various xenobiotics that provoke toxicological consequences. Waterbirds are potential sentinel species of these environments. To analyze how habitat conditions affect the health of Fulica americana, early-warning biomarkers, histopathology, somatic indices, and water quality were examined in two wetlands of the Basin of Mexico: Xochimilco, an urban wetland highly eutrophic with a mixture of pollutants, and Tecocomulco (the reference site), a rural wetland with hunting migratory birds in winter, and with some agricultural contaminants. Coots were collected over 1 year, and the birds were aged, eviscerated, and weighed. Liver samples were analyzed biochemically and histologically. Biomarkers revealed that coots displayed higher lipid peroxidation and elevated activities of gamma-glutamyl transferase and alanine aminotransferase, suggesting hepatic damage during autumn and winter. In Tecocomulco, coots during winter has the highest thiobarbituric acid reactive substances (as a measure of oxidative stress), which may be associated with the presence of predators. In Tecocomulco, the higher gonadosomatic index was detected in spring and summer, while in Xochimilco it was elevated in summer, indicating a delayed egg laying and reproduction in coots from the latter study site. In both wetlands, leukocyte infiltration, alone or combined with vasocongestion, reflected alterations in the inflammatory processes in liver throughout the annual cycle and thus potentially altered hepatic function and organism survival. In both wetlands, coots were permanent residents and chronically exposed to different stressors, suggesting damage may be irreversible with potentially adversely reproductive consequences.

Algal growth potential and oxidative stress in Ankistrodesmus falcatus exposed to waters from Xochimilco Lake system, México

The aim of this study was to assess the toxic effect of the water of Xochimilco Lake on a native microalgae species of the first trophic level, Ankistrodesmus falcatus. We evaluated oxidative stress (lipid peroxidation, and antioxidant activity of the enzymes: superoxide dismutase, catalase and glutathione peroxidase), and algal growth of A. falcatus, when exposed in bioassays to waters from three zones of Xochimilco Lake (urban, tourist, and agricultural), in four study periods; the responses were compared with those of a batch control. Water quality shows serious deterioration in the Xochimilco Lake system. Biomonitoring with biomarker responses provided information about the spatio-temporal impact of pollution on A. falcatus. Water samples of the three study zones of Xochimilco Lake induced oxidative stress in A. falcatus, and impaired its antioxidant enzymes and algal growth responses. Alteration detected in algal growth and oxidative stress of A. falcatus when exposed to waters from all sites and study periods make evident the toxic effect of the water from the Xochimilco Lake system.