Aflatoxin B1 toxicosis in dairy calves pretreated with selenium-vitamin E.

Effects of a single IM injection of selenium-vitamin E (Se-E; 5 mg of Se + 68 IU of alpha-tocopherol/60 kg of body weight) as a pretreatment 14 days before an oral dose of aflatoxin B1 (1.0 mg/kg) were studied in 24 dairy calves. Treatment groups were designated as follows: group 1 = no Se-E or aflatoxin B1 (control); group 2 = Se-E supplementation only; group 3 = aflatoxin B1 dose only; and group 4 = Se-E supplementation before aflatoxin B1 dose. Clinical signs of toxicosis in aflatoxin B1-treated calves included anorexia, ataxia, rough haircoats, increased respiration rates, dyspnea, dehydration, and nasal discharge. Packed-cell volume, RBC, WBC, and hemoglobin were increased in aflatoxin-treated calves. Significant increases in serum aspartate aminotransferase (P less than 0.05) and gamma-glutamyl-transferase (P less than 0.001) activities and prothrombin times (P less than 0.001) were observed in aflatoxin-treated calves, indicating that there was hepatic involvement. Although aflatoxin exposure caused a significant decrease in body weight (P less than 0.01) and feed intake (P less than 0.001) in treatment groups 3 and 4, Se was demonstrated to interact significantly (P less than 0.001) with aflatoxin B1 for feed intake, causing an improved feed intake in treatment group 4 calves.

Effect of dietary selenium on the metabolism of aflatoxin B1 in turkeys.

To investigate the biochemical mechanism of the previously reported protective effect of dietary selenium against aflatoxin toxicity, the hepatic metabolism of aflatoxin B1 in turkey poults was examined at various dietary selenium concentrations. Diets were supplemented with 0.2, 2.0 or 4.0 ppm selenium (as sodium selenite) and 500 ng aflatoxin B1/g diet in an 18-day trial. Free and conjugated aflatoxin and metabolites were quantified using high-performance liquid chromatography. The proportion of liver aflatoxins in conjugated forms increased and the ratio of free aflatoxin B1/M1 decreased with increasing dietary selenium concentrations. These in vivo results provide evidence of selenium-induced enhancement of aflatoxin detoxification processes. In a similar experiment using 2.0 ppm selenium and 750 ng aflatoxin B1/g diet, the concentration of hepatic reduced glutathione, cytochrome P-450 and the activity of enzymes involved in the metabolism of aflatoxin B1 and glutathione were determined. Although the selenium supplement increased glutathione peroxidase activity, dietary selenium had no effect on reduced glutathione or cytochrome P-450 concentrations or on the activities of glutathione transferase E, glucuronyl transferase and cytochrome c reductase. These data indicate that the protective action of selenium is not mediated by an increase in glutathione availability for aflatoxin conjugation or by effects on the activities of these enzymes as measured in vitro.

Aflatoxin B1 and Crotalaria toxicity in turkey poults.

El proposito del presente trabajo fue averiguar si habia un efecto toxico aditivo entre aflatoxina B1 y monocrotalina (el principio activo de la Crotalaria spectabilis), y determinar si los niveles de los toxicos administrados producirian residuos detectables en tejidos. Sesenta pavos, machos, saludables de un dia de nacidos fueron asignados al azar a cuatro grupos de tratamiento. Los bajos valores en proteinas totales, albumina, alfa-globulina, Beta-globulina, peso corporal, peso del higado en el grupo que recibio la combinacion de las dos substancias, fueron asociados a un efecto toxico aditivo de la Crotalaria y aflatoxina. Residuos de aflatoxina B1 y M1 fueron encontrados en los rinones de los animales que recibieron aflatoxina; y deshidroretronecina fue detectada en higados de los pavos que recibieron semillas de Crotalaria

Acute experimentally induced aflatoxicosis in the weanling pony.

Nineteen weanling ponies and 1 adult pony were given a single oral dose of aflatoxin B1 (AFB1). Dosages were: 0, 0.5, 1, 2, 4, 5, 6, and 7.4 mg of AFB1/kg of body weight. Vital signs were monitored, and whole blood and serum collected for analysis of serum enzymes, prothrombin time, blood cell counts, and serum urea nitrogen. Ponies that died were examined for gross lesions, and tissues were collected for histopathologic examination and analysis of AFB1 and AFM1 residues. Two of the 4 ponies given the 2 mg/kg dose and all ponies given the larger dosages died within 76 hours. Clinical signs included increased rectal temperature, faster heart and respiratory rates, abdominal straining, bloody feces, and tetanic convulsions. At necropsy, ponies that died of acute aflatoxicosis showed visceral petechiae and hepatic focal lesions. Histopathologic changes included severe hepatic necrosis, vacuolation, and bile duct hyperplasia. Aflatoxins B1 and M1 were recovered from liver, kidney, skeletal muscle, and gastrointestinal contents. One other pony given the 2 mg/kg dose died 32 days after dosing, and 1 control pony died after 70 days. Continuous elevations in prothrombin time and serum aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transpeptidase levels were observed in ponies dosed at 4 mg/kg or more. Significant (P less than 0.05) elevations in these values, which peaked 2 to 3 days after dosing, were seen in ponies given the 2 mg/kg dose. This group also had significant increases over controls in PCV and hemoglobin concentration 5 days after dosing.

Modification of the effects of aflatoxin B1 and warfarin in young pigs given selenium.

Selenium may be related to the hepatic metabolism of the coumarin compounds aflatoxin B1 and warfarin. Selenium evidently increased the pharmacologic activity of warfarin, probably due to a displacement of warfarin from albumin by selenium, the close relationship among selenium, vitamin E, and sulphur-containing groups (eg, glutathione), or the antioxidant effect of selenium. A diet containing selenium in a concentration of 2.5 mg/kg of feed was protective against the toxic effects of both coumarins in pigs given 4 daily oral doses of 0.2 mg/kg of body weight. Selenium, as glutathione peroxidase, at least in part, protects the hepatic cells against the toxic effects of aflatoxin B1 and warfarin. The protection was demonstrated by alteration of clinical responses and hematologic (prothrombin times), electrophoretic, and clinical chemistry values. It also was demonstrated that selenium at 2.5 mg/kg of feed does not produce toxic effects; however, dietary selenium at a concentration of 5 mg/kg (and in the presence of both toxic agents) was toxic for young pigs within the 3-week experimental period. Warfarin was more active as an anticoagulant than aflatoxin B1.

Influence of selenium on aflatoxin B1 or crotalaria toxicity in turkey poults.

This research compared the toxic effects of aflatoxin B1 and monocrotaline, the active principle of Crotalaria spectabilis, and the additive effect between aflatoxin B1 and monocrotaline in turkey poults. It was of interest whether selenium fed at dosage levels of 0.1, 5, or 10 micrograms/g of feed would protect against the toxic effect of aflatoxin and/or monocrotaline, and whether the toxicants would result in detectable residues in poult tissues. A total of 180 healthy 1-day-old male turkey poults was assigned at random to 12 treatment groups (15 birds/group). Body and liver weight losses, and low serum concentrations in total protein (TP), albumin (A), alpha-globulin (alpha G), and beta-globulin (beta G), as well as high values in gamma-globulin (gamma G), were produced in the groups fed crotalaria. Pathologic changes were induced by monocrotaline with no protection afforded by the added selenium. Low values in TP, A, alpha G, and beta G and in body and liver weights were observed in groups given the combination of aflatoxin plus crotalaria. Gross lesions were associated with an additive toxic effect and a lack of protective effect of selenium against this combination. However, higher values in TP, A, alpha G, and beta G, and liver weights in groups fed aflatoxin B1 plus selenium indicated that selenium had a protective effect against aflatoxin toxicity. Residues of aflatoxin B1 and aflatoxin M1 were found in the kidneys of poults fed aflatoxin B1; also, dehydroretronecine (the metabolite of monocrotaline) was detected in livers of poults fed Crotalaria spectabilis seeds.

Metabolite distribution and rate of residue clearance in turkeys fed a diet containing aflatoxin B1.

The retention of aflatoxin residues in tissues of turkey poults fed a diet containing aflatoxin B1 (500 ppb) for 18 days was determined. Free and conjugated aflatoxin metabolites were quantified using high-pressure liquid chromatography. Aflatoxin residue levels were greater in liver than muscle tissues, although all levels were low (range 0.01-1.19 ng/g tissue). Free and conjugated aflatoxins B1 and M1, a metabolite of B1, were the principal tissue residues. Other metabolites investigated included aflatoxicol, which was detected in certain samples, and aflatoxin Q1 which was not detected. Conjugated aflatoxins, hydrolysed and extracted from the aqueous tissue fractions, comprised 55-91% of the total detected aflatoxin residues. All aflatoxin residues were rapidly cleared following discontinuation of the dietary aflatoxin B1 (half-life 1.4 days for total aflatoxin clearance from liver). These results provide further evidence that tissues from animals maintained on diets containing aflatoxins do not provide a major source of aflatoxins when consumed by man.

Toxicology of aflatoxin B1, warfarin, and cadmium in young pigs: performance and hematology.

Observations on the interactions of cadmium (Cd) x aflatoxin B1 (AFB1) and Cd x warfarin included several variables of animal performance and hematology. Cadmium was fed daily for 40 days (groups IV, V, VI) and a Cd-free diet was fed to groups I, II, and III. Groups II and V were treated with AFB1, and groups III and VI were treated with warfarin--each for 5 days during the 5th week of the experiment and the effects were observed for 10 days. All pigs fed the diet with added Cd had developed severe anemia by the 4th week of the experiment. The incorporation of this toxic concentration of Cd (83 micrograms/g) in the diet seemed to have blocked the liver microsomal enzyme system (cytochrome P-450), diminishing the toxic effects of 5 daily oral doses (0.2 mg/kg of body wt) of AFB1 (group V pigs), but enhancing synergistically the toxic anticoagulant effects of the same doses of warfarin in young pigs (group VI). The data presented also indicated that the feeding of toxic concentrations of Cd stimulated increased glutathione peroxidase activity, which conjugated the AFB1 epoxides with their excretion as reduced glutathione but enhanced the toxic anticoagulant effects of warfarin in young pigs.

Toxicology of aflatoxin B1, warfarin, and cadmium in young pigs: clinical chemistry and blood coagulation.

The purpose of this experiment was to compare the toxic effects of aflatoxin B1 (AFB1) and warfarin in pigs and to determine whether these have an additive effect in these pigs fed dietary Cd. Cadmium was provided daily through the diets of 2 concentrations (0 or control, and 83 micrograms/g of diet) during the 40 days of the experiment. At the start of the 5th week, AFB1 and warfarin were given in 5 daily doses (each dose 0.2 mg/kg of body weight) and the effects were determined for 10 days (starting with the 1st treatment day). Aflatoxin B1 given to the pigs fed the control diet (0 Cd) was toxic, inducing significantly increased alkaline phosphatase, sorbitol dehydrogenase, and aspartate aminotransferase activities and the prothrombin time (PT) and activated partial thromboplastin time (APTT) and significantly decreased values in serum total protein, alpha-globulin, beta-globulin, gamma-globulin, and fibrinogen. There was no effect on blood urea nitrogen. The treatment with warfarin was more effective in producing earlier and significantly longer PT and APTT. In the pigs fed the diet with the added Cd, differences in activity of alkaline phosphatase, sorbitol dehydrogenase, aspartate aminotransferase values, but not blood urea nitrogen, as well as differences in intensity and duration of response in PT and APTT occurred when pigs were dosed daily for 5 days after AFB1 or warfarin. It is concluded that dietary Cd (83 micrograms/g of diet) in young pigs has an inhibitory effect on AFB1 toxicity and an enhancing synergistic effect with warfarin.

Toxicology of aflatoxin B1, warfarin, and cadmium in young pigs: metal residues and pathology.

The effects of feeding dietary cadmium (83 micrograms/g of diet) to young pigs on the distributions of copper, iron, and zinc in urine samples and in kidney, liver, and muscle tissues was determined. The diet with added Cd resulted in renal and hepatic tissue concentrations of 42.90 +/- 10.57 micrograms/g and 7.90 +/- 2.37 micrograms/g, respectively, at the 40th day of the experiment. Iron was found to decrease at the same time, which predisposed to the anemic condition of these pigs. The feeding of dietary CD to pigs prevented extensive fatty hepatocytic infiltration and severe jaundice, but not hydropic degeneration induced by aflatoxin B1. Cadmium increased the toxicity of warfarin with severe lameness, subcutaneous hematomas in the ventral surface of the neck, and death.

Comparison of serum bilirubin levels in humans and two monogastric animal species after a single administration of sulfisoxazole.

Administration of sulfonamides during periods of hepatobiliary failure or hepatic immaturity increases the toxic potential of unconjugated or indirect bilirubin. A small but statistically significant increase of indirect, or unconjugated bilirubin was noted in dogs after oral administration of sulfisoxazole (100 mg/kg). A similar increase was not observed in swine after oral or intravenous administration of sulfisoxazole (100 mg/kg) or in humans (approximately 28 mg/kg) after oral administration or in dogs (100 mg/kg) after intravenous administration. Total and conjugated bilirubin showed small but statistically significant increases and were significantly correlated in dogs after oral and intravenous administration of sulfisoxazole (100 mg/kg) and in swine after oral administration of sulfisoxazole (100 mg/kg). There was a significant negative correlation between conjugated and indirect bilirubin, while total bilirubin increased in dogs after oral and intravenous administration of sulfisoxazole. These data illustrate a difference in species and administration route when attempting to assess the potential toxicity of bilirubin.

The toxicity of Capparis tomentosa in sheep and calves.

Five Desert sheep and three Zebu calves were poisoned with daily oral doses of the dry leaves of Capparis tomentosa and died or were killed in extremis at various times after the commencement of dosing. The important clinical signs of Capparis poisoning in sheep and calves were weakness of the hind limbs, staggering, swaying, flexion of the fetlock and phalangeal joints, pain in the sacral region, inappetence and recumbency. There was decrease in the level of total protein and calcium and an increase of glutamic oxaloacetic transaminase (GOT), ammonia, sodium and potassium in serum. The main pathological changes were vacuolation of the neurons and axons in the spinal cord, with necrosis of the centrilobular hepatocytes and renal convoluted tubules and glomeruli.

Effects of aflatoxins in young ponies.

Sixteen clinically normal, healthy ponies were randomly assigned to 4 groups and given aflatoxin B1 in doses of 0.045, 0.030, 0.015, and 0 (control) mg/kg of body weight per day for 21 days (or total doses of 0.945, 0.630, 0.315, and 0 mg/kg). The animals were allowed to recover for 3 months and then were reassigned to 4 treatment groups such that each group during the 2nd trial included a pony from each of the groups of the 1st trial. The animals in the new groups were intubated and were given aflatoxin in doses of 0.4, 0.2, 0.1, and 0 (control) mg/kg/day for 5 days ( or total doses of 2.0, 1.0, 0.5, and 0 mg/kg). Venous blood samples were drawn every other day to monitor for toxicosis; examinations were made for RBC and WBC counts, hemoglobin concentration, PCV, serum urea nitrogen, prothrombin time, and serum concentrations of aspartate aminotransferase, iditol dehydrogenase, alkaline phosphatase, albumin, gamma-glutamyl transferase, and arginase. There were no significant differences between treatment groups and controls (given no aflatoxin) in the toxicologic values examined for during the 1st trial. During the 2nd experiment, 2 of the ponies in the large-dose treatment gorup (2.0 mg/kg) demonstrated increased serum enzyme activities. These animals had been in the large-dose (0.945 mg/kg) and median-dose (0.63 mg/kg) groups during the 1st trial. Arginase, iditol dehydrogenase, and gamma-glutamyl transpeptidase activities became increased on the 4th day of treatment and continued to increase until the 6th day of the experiment (1 day after treatment was terminated). These enzymes approached control group values at 10 days after cessation of treatment. These increases were indicative of hepatocellular toxicity. It was concluded that the possibility of equine aflatoxicosis exists although ponies given high quality rations appear to be less susceptible than some other species. Prior exposure to aflatoxins may predispose to clinical toxicity on subsequent exposure, despite lack of expression of clinical signs.

Pharmacokinetics of sulfisoxazole compared in humans and two monogastric animal species.

The pharmacokinetic profile of sulfisoxazole was studied and compared in dogs, swine, and humans. The trial was conducted over a 72-hr period after intravenous administration and a 96-hr period after oral administration in dogs and swine. In humans, the trial was conducted over an 8-hr period after oral administration. A two-compartment model system was used to define the pharmacokinetic profile. The mean half-lives for the distribution phase were 4.08, 1.30, and 0.56 hr in dogs, swine, and humans, respectively. For the elimination phase, the mean half-lives were 33.74, 46.39, and 7.40 hr in dogs, swine, and humans, respectively. The mean volume of the central compartment was approximately the same in dogs and swine, 10.6 and 10.5 liters, respectively. Humans had a smaller volume of distribution, 7.7 liters. The steady-state volumes of distribution were 17.2, 30.3, and 16.2 liters in dogs, swine, and humans, respectively. Dogs and swine excreted 42.2 and 30.7%, respectively, of the intravenous dose and 29.4 and 18.3%, respectively, of the oral dose. The bioavailability was 69.8% in dogs and 100.0% in swine. The fraction of drug bound ranged from 30 to 50% in dogs, 40 to 60% in swine, and 25 to 40% in humans.

Comparative toxicity of feeding dried urban sludge and an equivalent amount of cadmium to swine.

Three rations, an 18.71% protein swine starter diet (control), a basal diet containing 83 micrograms of Cd/g of diet, or a basal diet containing 50% Chicago sewage sludge (CSS) providing 83 micrograms Cd/g of diet, were given to weanling pigs for 9 weeks. Depressed growth occurred in both groups given Cd-treated diets in comparison with growth in pigs fed the control ration. Microcytic, hypochromic anemia occurred in the group given the Cd-supplemented diet, but there were no significant differences in the hematologic values between pigs in the control and CSS-supplemented diets. Toxicosis probably resulted from combining CSS as 50% of the diet due to a deficiency of available protein or other essential nutrients or from the accumulation of hazardous chemical residues including Cd, Cu, Cr, Hg, Ni, or Zn. An increased amount of Fe in the CSS-treated ration apparently protected the pigs against the microcytic, hypochromic anemia.

Toxicity of Datura stramonium to sheep and goats.

The toxicity of daily oral administration of Datura stramonium to Desert sheep and Nubian goats was studied. The main clinical signs were disturbances in locomotion, fasciculation, hyperesthesia, rapid respiration, and reduced water intake. There were increases in the concentrations of aspartate amino-transferase and ammonia and decreases of total protein and magnesium in the serum of Datura-poisoned animals. In this study Desert sheep appeared to be more susceptible to the effects of Datura stramonium than were Nubian goats.

Minicolumn detection methods for aflatoxin in raw peanuts: collaborative study.

The Holaday-Velasco method and a modified Holaday method have been compared. The former method combines the speed and simplicity of the Holaday extraction and cleanup with the sensitivity of the minicolumn originally described by Velasco. The combination method has been approved by the AOAC and the AACC for determining aflatoxin in corn. The Holaday method was modified by substituting toluene for benzene in the solvent partition, and methylene chloride for chloroform in the minicolumn development to eliminate use of hazardous solvents. The neutral alumina in the Holaday minicolumn was changed from activity V to activity III to provide a more stable column. At aflatoxin levels in raw peanuts of 13-20 ng/g, the presence of aflatoxin was missed by the modified Holaday method in 4 analyses (3 laboratories) of 42 reported. There were no misses in this contamination range by the Holaday-Velasco method. There were no misses by either method with samples containing greater than 20 ng total aflatoxins/g. Analysis of uncontaminated raw peanuts by the modified Holaday method resulted in 2 false positives of 14 reports; the Holaday-Velasco method produced no false positive reports from 15 analyses of uncontaminated peanuts. The Holaday-Velasco method was adopted official first action for peanuts.

Plasma concentration of iditol dehydrogenase (sorbitol dehydrogenase) in ponies treated with aflatoxin B1.

Twelve clinically normal Shetland ponies were allocated to one of four treatment groups. Aflatoxin B1 was administered at the dosage level of 2 mg/kg of body weight to group A, 1 mg/kg to group B, and 0.5 mg/kg to group C; a placebo was given to group D (controls). Plasma samples were assayed at 4-hour intervals for iditol dehydrogenase (ID) (sorbitol dehydrogenase) concentrations as an indicator of hepatic damage. One of the ponies in group A died 68 hours after dosing; another pony in group A died 76 hours after dosing. All other animals survived the experiment. The means of peak ID values were as follows: group A, 1514.0 IU/l (P < 0.05); group B, 192.6 IU/L (P < 0.05); group C, 8.5 IU/L (P < 0.05); and group D (controls), 2.7 IU/L. A square root transformation analysis of the postdosing response of ID values in relation to time demonstrated that the mean of group A became significantly higher (P < 0.05) than did the mean of the control group at 5 to 6 hours. The mean of group B at 12 to 16 hours and the mean of group C at 20 to 24 hours also were significantly higher (P < 0.05) than was the mean of the control group.