Electron Microscopic Observations of the Hepatocytes of Sheep in Lantana Poisoning

A study was made of the fine structure of the hepatocytes of 5 sheep affected with mild to severe lantana poisoning of from 1 to 7 days duration. For comparative purposes, observations were also made of the livers of both well fed and starved normal sheep and a CCl4 poisoned sheep 24 hours after dosing. The earliest and most consistent alteration of the fine structure of the hepatocytes in lantana poisoning was a characteristic separation of the interface plasma membranes with extensive formation of microvilli without significant cytoplasmic changes. This lesion is thought to be characteristic of this type of liver injury. In more severely affected livers, bile canalicular changes were accompanied by marked nuclear and cytoplasmic changes in many hepatocytes. These latter changes however, were considered to be mainly secondary and associated with the retention and regurgitation of bile

Directly toxic effects of plant chemicals which may occur in human and animal foods

Pyrrolizidine alkaloids are among the most significant plant chemicals causing disease in animals and humans. After absorption from the gut, the compounds are converted to electrophilic pyrroles in the liver which, apart from causing damage to this organ, may escape to cause injury to extraheptic tissues such as the lungs, heart, and kidneys. A group of compounds more recently found to be associated with neurotoxicity are various polyhydroxyalkaloids which are able to interfere with polysaccharide metabolism. They are able to inhibit lysosomal monosaccharidases by virtue of their structural resemblance to the transition state of particular sugar molecules. The resulting lysosomal storage diseases have pathology identical to that of the respective congenital and heritable lysosomal storage diseases which occur in animals and humans. Consumption of cycad plants by cattle may cause a neurotoxicity characterised mainly by a posterior sensory ataxia. In recent years, cycads are considered to be a risk factor for a spectrum of progressive neuro degenerative diseases of humans in the Western Pacific region. The known toxins in the plant are the methylazoxymethanol glycosides which are hepatotoxic and carcinogenic, and the neurotoxic non‐protein amino acid β‐methylaminoalanine. A plant carcinogen which can be of great abundance in the nutritional environment is the illudine norsesquiterpene glucoside ptaquiloside which is found in bracken fern. This is the only plant carcinogen which causes natural outbreaks of bladder and/or intestinal cancer in livestock. Many legumes contain phytooestrogens, notably isoflavones. Consumption of these compounds at high levels by sheep can cause extensive lesions of the genitalia of females and castrated males. A chronic long‐term effect of excessive oestrogen intake in ewes is “masculinization” of the internal genitalia leading to reduced fertility. The presence of such compounds in the diet may be associated with reproductive disorders in man. © 1995 Wiley‐Liss, Inc. Copyrigh

Generalised Amyloidosis in Seven Cats

Seven casts of generalised amyloidosis in the cat, occurring in 100 consecutive cat autopsies, were studied pathologically. Tissues from 2 of the cats were further investigated using the electron microscope. None of the cats had suffered from a prolonged infection, but one had had chronic allergic dermatitis. In 6 of the 7 cats chronic hypervitaminosis A coexisted with generalised amyloidosis. It is suggested that chronic hypervitaminosis A, which causes prolonged stimulation of the reticulo-endothelial system, may have predisposed to the high incidence of generalised amyloidosis reported in this paper

Experimental ochratoxicosis A in pigs

SUMMARY Ochratoxin A was isolated from a culture of Aspergillus ochraceus grown on a cornmeal substrate. The mycotoxin was added to a grower ration for 14 kg young pigs at 2, 4, 8 and 16 mg/kg and fed to groups of 3 for periods ranging from 6 to 20 days. The highest dose rate group only became sick, with loss of appetite, weight loss, polydipsia, polyuria, proteinuria, glucosuria, elevation of serum creatinine, pale swollen kidneys, renal tubular degeneration and cortical fibrosis. The pigs on the 2 mg toxin/kg of diet appeared unaffected with only slight renal tubular degeneration present in one animal. Feeding diet contaminated with the intermediate doses of 4 and 8 mg toxin/kg diet lead to reduction of weight gain and/or reduced feed intake and feed conversion efficiency as well as mild renal lesions. Ochratoxin A has recently been reported on mould‐affected grain in Queensland and some local strains of A. ochraceus in culture have been shown to be able to produce levels of ochratoxin A of up to 4000 mg/kg of substrate. Rare episodes of nephrotoxicity in pigs seen at slaughter in Queensland may thus be due to prior contamination of the diet with ochratoxin A. Copyrigh