Intoxication of sheep with quebracho tannin extract.

This experiment was carried out to study the toxicity of quebracho tannin extract (containing 760 g of condensed tannins [CTs] per kg), with the aim of validating its use as a feed additive for improving the digestive utilization of protein-rich feeds. Four groups (Q(0), Q(1), Q(2) and Q(3)) of four sheep were dosed intra-ruminally once daily, for up to 21 days with, respectively, 0, 0.5, 1.5 or 3.0 g quebracho tannin extract/kg live-weight (LW). Feed intake, live-weight changes, plasma biochemistry, indicators of hepatic detoxification function, gross lesions and histopathology were examined. Animals in groups Q(0), Q(1) and Q(2) consumed all the offered feed. In contrast, feed intake was practically nil after 6 days of quebracho dosing in group Q(3), this being associated with a loss of 4.7+/-1.30 kg LW in 10 days (P<0.05). Sheep from groups Q(0), Q(1) and Q(2) remained healthy throughout the experiment. Ewes from group Q(3) became weak and depressed on day 5 and after 8 days of dosing remained recumbent. They were humanely killed after 10 days to avoid suffering. In general, neither gross lesions nor microscopical changes were observed in animals from groups Q(0), Q(1) and Q(2). However, Q(3) sheep showed striking lesions in the digestive tract (well-demarcated ulcers filled with necrotic material in the mucosa of the rumen and reticulum, distension of abomasum and small intestine, and dense mucous material in the caecum), and changes in plasma biochemistry. Cytochrome P-450 and glutathione concentrations were significantly reduced in Q(3) sheep (P<0.05). It is concluded that quebracho tannin extract is not toxic for ruminants, except in concentrations too high to be encountered under practical conditions.

Accuracy of the one-sample method for determination of antipyrine clearance in elderly subjects.

The purpose of this study was to evaluate the validity of the one-sample abbreviated method for determination of the pharmacokinetic parameters of antipyrine in the elderly. Antipyrine pharmacokinetics were studied in 15 elderly women (mean age 86 years). Antipyrine (1 g) was administered orally and pharmacokinetic parameters were determined by the one-sample (24 h) and multiple-sample (3, 6, 9, 12 and 24 h) methods. Mean antipyrine clearance for the one-sample study (19.72 +/- 1.51) was almost identical to that obtained with the multiple-sample approach (20.73 +/- 1.57), and the two methods were very well correlated (r = 0.989). Relative standard deviations between individual clearances values for multiple-sample vs. one-sample studies averaged 1.6%. Values of elimination half-life were likewise very similar for the abbreviated (17.41 +/- 1.21) and complete (17.99 +/- 1.09) methods, with a significant correlation (r = 0.857). Although values were underestimated by 10% in the one-sample approach, no difference in the volume of distribution with the multiple-sample study was observed. When the unbiased volume of distribution value was determined from the total elimination curve against time, the influence of biased volume of distribution resulted in a 5.1% deviation in antipyrine clearance in the one sample method. The findings indicate that antipyrine pharmacokinetic parameters can be estimated with reasonable precision and accuracy in the elderly using a simplified one-sample procedure.

Effects of aging on antipyrine clearance: predictive factors of metabolizing capacity.

The purpose of this study was to identify variables that can account for the decline of antipyrine clearance (CLAP) in elderly adults and that may help predict a reduction in metabolizing capacity. For comparison, ClAP was determined in 177 elderly (mean age 82 years) and 25 young (mean age 29 years) volunteers. Antipyrine (1 g) was administered orally and ClAP was determined by the one-sample saliva method. Mean ClAP was reduced by 38% and antipyrine half-life increased by 64% in old subjects. Multiple regression analysis of ClAP revealed an independent value for age, serum aspartate transaminase (AST), and height in the elderly. The independent variables collectively accounted for 27% of the variance explained. Age, high serum AST, use of diuretics, and no consumption of drugs known to stimulate oxidative metabolism were selected by multivariate analysis (logistic model) as independent predictors of a low metabolizing capacity. The findings indicate that factors other than age may contribute to impaired hepatic oxidative metabolism in the elderly.

Assessment of antipyrine kinetics from saliva or plasma: influence of age.

The purpose of this study was to investigate whether antipyrine estimation in saliva provides valid information on plasma antipyrine clearance (APCl) and can be useful as an index of changes in drug metabolism with age. Antipyrine kinetics was studied in 93 elderly (mean age 82 years) and 23 young (mean age 29 years) volunteers. Plasma antipyrine half-life (APt1/2) increased and plasma APCl declined with age. No significant difference between plasma- and saliva-derived parameters was found in either young or old subjects. However, the saliva/plasma ACCl ratio tended to increase with age. A highly significant correlation between saliva and plasma APCl or APt1/2 was found in young subjects. Values were less closely related in the elderly and the slope of the saliva/plasma APCl relationship was significantly different in both groups of subjects. Residual variance was higher in the regressions corresponding to the elderly. The findings in the study indicate that the relationship between saliva and plasma kinetics in young subjects becomes less reproducible with age.

Impairment of bile secretion induced by exhaustive exercise in the rat. Protective effects of S-adenosyl-L-methionine.

The effects of strenuous exercise on the mechanisms of bile formation were studied in rats. Animals (n = 8) were exercised to exhaustion in a rodent treadmill at a speed of 24 m/min and a 12% slope. Hepatic glutathione concentration was significantly reduced (-40%) and liver malondialdehyde content significantly increased (+37%) when compared to sedentary controls (n = 6). Both serum alkaline phosphatase level and bile acid concentration were significantly higher in runners (+81% and +85%). Bile flow and the biliary secretion of bile acids were significantly reduced both in basal conditions and following an i.v. taurocholate infusion (0.5 mumol/min/100 g body wt). Biliary glutathione secretion was also significantly decreased following exercise. Cholestasis was caused by an impairment of both bile acid-dependent (BADF) and bile acid-independent fraction (BAIF) of bile flow (-25% and -29% respectively). Exercise caused a delay in the peak appearance time and a reduced biliary secretion of horseradish peroxidase, suggesting alterations in the functional integrity of the cytoskeleton. To test the protective effects of S-adenosyl-L-methionine (SAMe), rats received the drug for ten days at a daily dose of 8 mg/kg i.p. SAMe administration prevented hepatic glutathione depletion due to exercise, normalizing both bile flow and bile acid as well as glutathione secretion. Our results suggest that both glutathione depletion and alterations in fluidity and composition of hepatocyte membranes could contribute to the development of exercise-induced cholestasis.

The activity of glutathione S-transferase in hepatopancreas of Procambarus clarkii: seasonal variations and the influence of environmental pollutants.

1. The glutathione S-transferase activity in hepatopancreas of the American red crayfish Procambarus clarkii after 15 days' acclimatization in tap water aquaria was measured in specimens collected monthly for a whole year, and shows seasonal variation. 2. Previous data on the environmental pollution of Lake Albufera suggest a possible correlation with the activity tested in the different seasons of the year considering the results of non-acclimatized animals.

Changes in the biliary excretion of organic anions following exhaustive exercise in rats.

The effect of exhaustive exercise on the hepatobiliary transport of organic anions was investigated in rats. Animals were run on a rodent treadmill at 24 m/min up a 12% grade (152 +/- 15 min). Exercise resulted in significant hypoglycaemia (-46%) and increased plasma levels of lactate (+12%), together with a marked reduction of glycogen concentration in the liver (-72%). When bromosulphthalein was administered i.v., its maximal biliary excretion (Tm) was significantly reduced (-30%), and plasma and liver concentrations of the dye were increased (+31% and +56%, respectively). The decrease corresponded both to the excretion of the conjugated and unconjugated dye (-30% and -33%, respectively). Cytosolic glutathione S-transferase activity in the liver was not affected by exercise, but there was a significant reduction in the hepatic concentration of glutathione (-50%). The Tm of dibromosulphthalein was also significantly reduced (-36%) and its plasma and liver concentrations increased (+67% and +33%, respectively) in exercised rats. The results suggest that, in addition to the direct effect of liver glutathione depletion, other factors must be involved in the impairment of the biliary excretion of organic anions caused by exercise.

Glutathione transferase activity in some flagellates and amoebae, and purification of the soluble glutathione transferases from Acanthamoeba.

Glutathione transferase (GST) enzymes are toxicologically important from many points of view. Nine protozoans were investigated here for their GST content. Six aerobic amoebae had very different specific GST activities, but an anaerobic amoeba and two anaerobic flagellates did not have any GST activity, suggesting that the peroxidase activity of GST is an evolutionarily important property for aerobic organisms. The soluble GST isoenzymes of Acanthamoeba culbertsoni and A. polyphaga were purified and partially characterized. The same two cationic and one anionic GST isoenzyme were found in both Acanthamoeba ssp., while A. culbertsoni had one more cationic isoenzyme. It is concluded that GST in aerobic amoebae can play an important role in detoxication.

In vitro interaction of mercury, copper (II) and cadmium with human glutathione transferase pi.

The in vitro interaction of mercury, copper (II) and cadmium with human glutathione transferase (GST) pi was studied using reduced glutathione (GSH) and 1-chloro-2,4-dinitrobenzene as substrate. Tumor specific human GST pi was isolated from the human hepatoma derived PLC/PRF/5 cell line. The inhibition of the GST pi activity was dose dependent. Kinetic studies never revealed competitive inhibition. A parabolic inhibition was found with GSH as the variable substrate. The heavy metals are spontaneously conjugated with GSH and cysteine, but interact with GST pi by direct binding to this protein. This binding could have a protective function against heavy metals.

Lethal toxicity of Lindane on a teleost fish, Anguilla anguilla from Albufera Lake (Spain): hardness and temperature effects.

This paper reports the results of toxicity tests conducted using Anguilla anguilla under three different water temperature (15, 22 and 29 degrees C) and two hardness regimes (250 and greater than 600 ppm CaCO3). The 96-h LC50 increased in the experimental medium (p less than 0.05) by an order of magnitude from 0.32 to 0.45 mg/L between 15 and 29 degrees C. However in the natural medium it is similar (p greater than 0.05) (0.54 to 0.55 mg/L) for these same temperatures. The toxicity of Lindane on eels increased when the water hardness decreased. The 24, 48, 72 and 96-h LC50 for this fish in both media is less at 15 degrees C (96-h LC50 = 0.32 and 0.55 mg/L) than at 29 degrees C (96-h LC50 = 0.45 and 0.55 mg/L). These results suggest that the toxicity of Lindane presents a negative temperature coefficient.

The effect of two sulphur-containing pesticides, fenitrothion and endosulfan, on glutathione (GSH) content and on GSH S-transferase and gamma-glutamyl transpeptidase activities in midgut gland of the American red crayfish Procambarus clarkii.

The glutathione (GSH) system of Procambarus clarkii (P.c.), the American red crayfish, is used as a marker of the effects of Fenitrothion (FT) and Endosulfan (ES), organophosphorus and organochlorinated insecticides, respectively. This system has been shown to be sensitive to different heavy metals poisoning, thus it has a double interest as marker for environmental contamination and as a potential source of xenobiotics or their metabolites to humans, since it is being fished commercially. The GSH content of the organ decreased 24 h after treatment with FT. FT promotes a 2-fold induction of GSH S-transferase (GST) activity at 6 h which is followed by a decrease of it at 24 h. The latter coincides with the decrease in GSH content. GST activity increases again over the control values at 48 h. Only the initial increase in GST activity is coupled with an increase in gamma-glutamyl transpeptidase (transpeptidase activity) (gamma-GT) activity. ES promoted a discrete increase in GSH concentration at the same time as a 2-fold increase in GST activity, again coupled with an increase in gamma-GT activity. The GST induction observed at 6 h with FT and 24 h with ES showed concentration dependency up to 1/4 of the reported LC50 of both pesticides. Higher concentrations showed no further effects on GST activity. The coupled control of the expression of GST and gamma-GT in the hepatopancreas of P.c. is discussed.

Glutathione content and GSH S-transferase activity in midgut gland of Procambarus clarkii. Sex differences, the effect of fasting, and their implications in cadmium toxicity.

1. Glutathione content and GSH S-transferase activity in the midgut gland of Procambarus clarkii (P. c.) of different sex and body weight are presented. 2. Procambarus clarkii females' GSH concentration in the midgut gland decreases to a higher extent upon fasting, compared with males. 3. Procambarus clarkii females, both in control and fasting conditions, have a slightly higher GSH S-transferase activity than males. 4. Cadmium present in water only affects GSH content and GSH S-transferase activity (after 96 hr) in midgut gland, with cadmium chloride concentrations higher than 100 micrograms/l.

Toxicity of some ricefield pesticides to the crayfish P. clarkii, under laboratory and field conditions in Lake Albufera (Spain).

Static toxicities in mature crayfish (Procambarus clarkii) were determined, for eight insecticides, two herbicides and one fungicide which were frequently used in rice cultivation at Lake Albufera in Valencia (Spain). Three concentrations of each product were used: a) The concentration that was recommended by the dealer (in mg/L of active ingredient): Carbofuran 0.40, Carbaryl 0.80, Malathion 0.80, Trichlorfon 0.40, Endosulfan 0.56, Lindane 0.56, Fenitrothion 0.40, Cyfloxylate 0.02, Molinate-Thiobencarb 1.50, Copper Sulfate 0.42, b) Half of the recommended concentration. c) Double of the recommended concentration. In all three of the concentrations tested, only Fenitrothion and Cyfloxylate caused a considerable mortality. The other ones do not actually produce any important effects on P. clarkii in our conditions. Nevertheless, insecticides are more toxic than herbicides or fungicides, as the latter show a rather low toxicity.