Charles H. Bridges

Kleingrass (Panicum coloratum L.) Poisoning in Sheep

Twenty-four lambs grazing pastures of Panicum coloratum developed photosensitization secondary to hepatic dysfunction. Lesions were necrosis of scattered hepatocytes, obstruction of small bile ducts and bile canaliculi by small aggregates of birefringent crystals, and accumulation of birefringent crystals in phagocytes within sinusoids. The number of crystals in livers of affected sheep varied, depending on the amount of time of exposure to toxic plants and severity of hepatic abnormalities. Crystals in the liver were soluble in acidified ethyl alcohol, acetic acid, pyridine, chloral hydrate, and methanol, but not in xylene, petroleum ether, diethyl ether, acetone, water, or cold ethyl alcohol. Crystals were not stained by oil red O. There was necrosis of epithelial cells in renal distal convoluted tubules, papillary muscles of the heart, and the adrenal cortex. Lesions of Panicum coloratum-associated disease are similar to those associated with photosensitization induced by Tribulus terrestris, Agave lecheguilla, and Nolina texana.

Neuronal Lipodystrophy. Occurrence in an Imbred Strain of Cattle

Spontaneous neuronal lipodystrophy with visceral involvement is reported in a bull of an inbred strain of cattle. The presence of neuronal inclusions similar to the multilamellar cytosomes and curvilinear bodies described in a type of late infantile amaurotic idiocy and a neurovisceral storage disease in man was demonstrated by light microscopy and confirmed by histochemistry and electron microscopy.

The effects of chronic carbaryl administration on the neuromuscular system of swine.

Abstract Two pigs from a litter of 13-week-old specific pathogen-free pigs were fed a ration containing the cholinesterase-inhibiting insecticide carbaryl (Sevin®) (1-naphthyl- N -methyl carbamate), at the rate of 150 mg/kg (live weight) daily for 72 and 83 days, respectively. Three pigs from the same litter were fed 150 mg/kg of carbaryl daily for 4 weeks and then 300 mg/kg per day, the total feeding period being 46 and 85 days, respectively. Two pigs were maintained on the basal ration as controls. The clinical syndrome of chronic intoxication was characterized by progressive myasthenia, incoordination, ataxia, intention tremor, and clonic muscular contractions terminating in paraplegia and prostration. The females in each group required a larger total dose of carbaryl to induce paralysis and death than did the males. Lesions were confined to the central nervous system and skeletal muscle. The muscular lesions consisted of three morphologically distinct forms: a discrete myodegeneration of traumatic or ischemic type, an acute hyaline and vacuolar myodegeneration healing by discontinuous regeneration, and an acute degenerative process associated with dystrophic calcification apparently centered upon mitochondria or the sarcotubular system. Moderate to severe edema of the myelinated tracts of the cerebellum, brain stem, and upper spinal cord was associated with vascular degenerative changes. The pattern was consistent with a vasogenic type of edema.

Cerebrospinal Lipodystrophy in Swine A New Disease Model in Comparative Pathology

Spontaneous lipidosis of the central nervous system of two Yorkshire swine is reported. The presence of membranous cytoplasmic neuronal inclusions similar to those reported in Tay-Sachs disease in man was confirmed by electron microscopy.

The role of lysosomes in the pathogenesis of copper-induced hepatotoxicity: Morphological studies

Copper-induced hepatotoxicity was evaluated in beige and conventional mice which were injected intraperitoneally with aqueous copper chloride (8 mg per kg body weight per day). Hepatic lesions developed more quickly and were more severe in beige mice and consisted of karyomegaly, progressive accumulation of lipofuscin within hepatocytes and Kupffer cells, acute necrosis of random hepatocytes, and aggregation of leukocytes within the sinusoids. In both groups of mice the hepatic lesion had a centrilobular distribution and closely paralleled the appearance and distribution of copper within hepatocytes. Overall, beige mice had more severe copper-mediated hepatotoxicity, suggesting that normal lysosomes have protective effects for hepatocytes by sequestering copper from other cytoplasmic constituents.

The role of lysosomes in the pathogenesis of copper-induced hepatotoxicity: II. Intracellular distribution of copper in hepatocytes

The effects of altered lysosomal function on the pathogenesis of copper-induced hepatotoxicity were studied in C57B1/6 bg/bg (beige) and C57B1/6 bg/+ (conventional) mice. Copper loading was accomplished through daily ip injections of aqueous copper chloride at a dosage rate of 8 mg/kg body weight for 1, 2, and 4 weeks. The subcellular distribution of copper in copper-treated beige mice was significantly different than that in conventional mice. Beige mice had consistently higher levels of copper in the nuclear and cytosolic fractions with lower levels in the heavy and light mitochondrial fractions. The copper levels were lowest in the microsomal fractions of both groups of copper-treated mice and remained similar throughout the 4-week experiment. Levels of total hepatic copper were similar in both groups of mice receiving parenteral copper except at Day 14, when beige mice had higher levels.

The Lesions of Hepatic Fatty Cirrhosis in Sheep

During a natural outbreak of hepatic fatty cirrhosis (HFC) in western Texas, 500 2-6-year-old Rambouillet ewe sheep were sequentially studied to determine the pattern of lesion development. All sheep developed lesions of HFC. Grossly, changes first began in the subcapsular hepatic parenchyma along the porta hepatis and spread peripherally until, in the final stages of the disease, approximately 80% of the liver was affected. Ascites, hydropericardium, and acquired hepatic vascular shunts were present in sheep with severe HFC. Light microscopic lesions initially appeared as accumulations of fine lipid droplets in the cytoplasm of periacinar hepatocytes but, with time, involved all hepatocytes of the lobule. The fat vacuoles in the periacinar hepatocytes coalesced to form larger vacuoles; and after rupture of adjacent fat-laden hepatocytes, fatty cysts appeared. Fibrosis began in the periacinar zone associated with the ruptured fatty cysts and continued until there was widespread bridging periacinar fibrosis. Islands of regenerating hepatocytes were frequently sequestered within the bands of fibrous tissue. Characteristically, the hepatic and posterior mediastinal lymph nodes, lung, and spleen contain ceroid. No lesions of hepatic encephalopathy were found in any animal. HFC is a progressive, chronic disease of sheep, and the morphology of the hepatic lesions is similar to lipotrope-deficient forms of nutritional cirrhosis. These findings are discussed in relation to similar nutritional deficiencies and toxicoses in sheep.

The developmental toxicity of an isolate from the plant Solanum dimidiatum (potato-weed) in Syrian golden hamsters.

The developmental toxicity of an ethanol extract from Solanum dimidiatum was investigated in date-bred Syrian golden hamsters. Neural tube defects were seen in three Syrian golden hamster fetuses, from one litter out of 12, at a maternal dose of 1.52 mg of plant isolate per g of body weight. Other malformations observed were syndactyly in a single fetus, from one litter out of ten, in the 0.45 mg/g dose group and gastroschisis in a single fetus, from one litter out of nine, in the 1.01 mg/g dose group. These findings suggest minimal developmental toxicity for this plant isolate.

An alternative extraction procedure for the isolation of sporidesmin from Pithomyces chartarum

Abstract An alternative bulk extraction method has been developed for the isolation of sporidesmin from ryecorn cultures of Pithomyces chartarum (Berk. & Curt.) M. B. Ellis. Based on 32 consecutive extractions, an average yield of 165.5 mg sporidesmin-benzene solvate per kg ofculture material was achieved, representing a 28-65% increase in yield over previously published results. Furthermore, the extraction process is rapid and can be conducted under normal laboratory conditions without significant loss of sporidesmin through degradation.