Acute liver injury in ducklings as a result of aflatoxin poisoning

Biochemical studies of transient intermediates in relation to chemical carcinogenesis

Many chemical carcinogens must be metabolized to chemically reactive transient species before they can exert their full toxic action on mammalian cells. In general, this metabolic activation is performed by NADPH-dependent enzymes in the endoplasmic reticulum; the NADPH-cytochrome P-450 electron-transport chain is very important in this respect. Biochemical studies on the chemical reactivities of such transient intermediates require the application of various fast-reaction and free-radical techniques: the use of such techniques is illustrated by reference to the metabolism of carbon tetrachloride. CCl4 is metabolized by liver endoplasmic reticulum in the presence of NADPH to a highly reactive product, probably CCl3; this activation of CCl4 results in covalent binding of CCl3 and lipid peroxidation. The steady-state concentration of CCl3 is too low to be measured directly by e.s.r. spectroscopy but radical species can be accumulated with spin-trap techniques. The CCl3 radical can be generated by pulse radiolysis and the ensuing reactions with biologically important neighbouring species can be followed in the microsecond range by kinetic spectroscopy. The results point to the high reactivity of CCl3 and its restriction to a microenvironment within the endoplasmic reticulum. Highly reactive electrophilic radicals (e.g. CCl3) can initiate lipid peroxidation in biomembranes and this is associated with changes in polyunsaturated fatty acids and in membrane fluidity. The results are discussed in relation to carcinogen activation, to free-radical-mediated reactions in biomembranes, and to the general thesis that the production of reactive aldehydes by lipid peroxidation may act as a 'coarse control' of cell division.

Toxicity of 2-hydrazinoethanol in turkey poults

1. Toxicity of 2-hydrazinoethanol was investigated in turkey poults 2-6 weeks posthatch. 2. Significant depression of body wt was evident at concentrations of the drug as low as 10 ppm. 3. Severe anorexia closely paralleled a highly significant decrease in water intake. 4. A significant increase in the ratio of granulocytes to agranulocytes was seen in poults fed the drug at a dose of 50 ppm. 5. Under the conditions of this experiment, none of the tissues sampled exhibited pathologic changes consistent with drug injury.

Ultrastructural changes induced by chronic aflatoxicosis in chickens

Effects in chickens of a low concentration of aflatoxin in the diet were investigated. After eight weeks, heart, pancreas, and liver tissues were examined by electron microscopy. Most damage was to liver; changes were observed both in individual parenchymal cells and in tissue organization. Proliferation of bile duct epithelial cells was extensive. The pancreas showed little change and was, therefore, a good organ for observation of early and/or mild ultrastructural changes associated with aflatoxicosis. The priority of initial nuclear change over cytoplasmic change was indicated in this organ. In the myocardium, the only significant changes were in mitochondria. Mitochondria of liver and pancreas were not altered. Leukoviruses were observed in the tissues of one aflatoxin-treated bird.

Hepatic cholesterol-lipid anomalies induced by aflatoxin

A diet of 60% peanut meal (W.H.O/F.A.O/U.N.I.C.E.F) was fed either toxin free or adulterated with aflatoxin at the rate of 0.948 μg B1 and 0.630 μ G1 to ducklings for a 10-day period. The ingestion of aflatoxin increased from 14.99 in 16.70 μg per day per duckling with outward signs of repression of growth and reduced feed efficiency as measured by changes in weight. Compared with those ducklings fed a toxin-free food, aflatoxin resulted in an increase of the liver in size from 3.8 to 4.4%; total hepatic lipids of the intoxicated ducklings decreased from 23.0% to 14.0% while cholesterol remained above 22% with marked contrast in crystalline form and cellular distribution. Normal changes in triglycerides were reversed with oleic and linoleic acids increased while palmitic and stearic acids were decreased. Levels of linoleic acid were significantly higher within ducklings fed the aflatoxin diet.