Generalized Equine Cutaneous Mastocytosis.

A newborn foal developed generalized cutaneous mastocytosis characterized by multiple elevated nodules of mast cells in skin and basophil hyperplasia in bone marrow. Skin lesions began as small aggregates of mast cells that progressively enlarged, ulcerated, and regressed spontaneously. Eosinophil infiltration, collagen necrosis, and fibroplasia were characteristic of advanced lesions. Many new lesions developed during the first month of life but numbers progressively diminished. Large numbers of mast cells were present in biopsies of lymph node, spleen and bone marrow. Discrete aggregates of mast cells were present in the bone marrow postmortem but no other significant change was seen. Mast cells contained large amounts of histamine but little serotonin. Ultrastructurally, their cytoplasmic granules were chiefly granular with few dense forms. In cell culture, mast cells from early lesions maintained mitotic activity through 14 passages. Cells obtained from older lesions were rapidly overgrown with fibroblasts. An equine herpesvirus isolated from cultures of cutaneous mast cell lesions and of spleen was not thought to be related to the disease.

Experimental toxoplasmosis in calves and pregnant cows.

Experimental Toxoplasma gondii infections were studied in pregnant cows and in calves. In tests to compare their virulence, three strains of the toxoplasmal parasite were red to cats; then fecal oocysts were collected and given per os to calves. In tests to determine their effects, virulent tachyzoites or oocysts were given to 10 calves and to 22 pregnant cows by the oral, IV, or intraamniotic routes. Clinical signs were fever and inappetence. One cow in early gestation aborted 24 days after IV administration of tachyzoites. Gross and microscopic changes were slight and nonspecific. Toxoplasmas were isolaated from brain or liver of 4 cows, placenta of 2 cows, gastric contents of 2 near-term fetuses, and blood and tissues of calves. Toxoplasmas were not isolated from control cows.

Ultrastructural studies of a visna-like syncytia-producing virus from cattle with lymphocytosis.

A virus structurally similar to viruses associated with maedi, progressive pneumonia, and visna of sheep has been isolated from buffy coat cells of cattle with chronic lymphocytosis. Electron microscope studies revealed three variants of the virion: (i) an intracytoplasmic form 98 to 116 nm in diameter when occurring in a nonlaminated form, (ii) a budding form 120 to 130 nm in diameter, and (iii) an extracellular form 80 to 130 nm in diameter and containing a 30 to 43 nm eccentrically located electron-dense core.

Correlations between gross and microscopic lesions in carcinogenic studies in mice.

Microscopic diagnoses of a number of spontaneous and induced neoplasms in mice were correlated with the gross findings of the ED01 and a number of other carcinogenic studies conducted at NCTR to determine the value of detailed histopathologic examinations in bioassay testing. The results indicated that for organs such as thymus, lung, adrenal, Harderian gland and urinary bladder 50% or more of the neoplastic lesions would be missed if at least one histological section were not examined from each organ. For organs such as the liver and mammary gland, a single tissue section did not greatly improve the ability to detect neoplastic lesions beyond that afforded by a thorough necropsy examination.

A lysosomal storage disorder in mice characterized by the accumulation of several sphingolipids.

A strain of BALB/c mice with an autosomal recessive neurologic disorder has been reported previously [1, 2]. The tissues of affected animals have been further examined and the activities of varius lysosomal hydrolases and levels of sphingolipids were compared to those in control mice. There was a substantial diminution of sphingomyelinase and glucocerebrosidase activities in liver, spleen, lung, thymus, and kidney of affected mice. There was a corresponding accumulation of sphingomyelin and glucocerebroside in these tissues. The activity of several other lysosomal hydrolases was elevated. Heterozygotes did not show any of the enzymatic alterations. The brain of affected animals showed substantial accumulation of the gangliosides GM3 and GM2.

A genetic storage disorder in BALB/C mice with a metabolic block in esterification of exogenous cholesterol.

Cholesterol metabolism has been investigated in a strain of BALB/C mice that carry an autosomal recessive mutation associated with decreased sphingomyelinase and glucocerebrosidase activity and storage of sphingomyelin and glucocerebroside as well as cholesterol in lysosomes (Pentchev, P. G., Gal, A. E., Boothe, A. D., Omodeo-Sale, F., Fouks, J., Neumeyer, B. A., Quirk, J. M., Dawson, G., and Brady, R. O. (1980) Biochim. Biophys. Acta 619, 669-679). When affected animals are placed on a diet high in cholesterol, they develop hepatomegaly associated with an extensive accumulation of unesterified cholesterol in the liver. Cultured skin fibroblasts derived from these mice also manifest a defect in cholesterol esterification although the uptake and intracellular location of exogenous cholesterol is comparable to that of controls. Microsomal fatty acyl-CoA:cholesterol acyltransferase activity was normal or elevated in extracts of tissues from the affected animals. Furthermore, the subcellular distribution and membrane orientation of acyl-CoA:cholesterol acyltransferase appeared normal in microsomal preparations isolated from affected mice. The blockage of esterification of exogenous cholesterol in the presence of normal transferase activity is suggestive of a defect in a component involved in the intracellular disposition of this sterol. The attenuation in tissue levels of sphingomyelinase and glucocerebrosidase and the accumulation of sphingolipids may reflect alterations in lysosomal function resulting from an imbalance of unesterified cholesterol in these organelles.

Comparison of olestra absorption in guinea pigs with normal and compromised gastrointestinal tracts.

Female guinea pigs (12/group) were given a single dose of [14C]olestra by gavage after consuming either 3% poligeenan in tap water (Compromised group) or just tap water (Normal group) for 5 weeks. A Sentinel group (N = 2) was given 3% poligeenan for 5 weeks. Ten sentinel animals were killed 1 day before and 10 1 day after the other animals were dosed with [14C]olestra and their gastrointestinal tracts were examined by histology. The Compromised and Normal animals were endoscoped just before dosing with [14C]olestra. Urine and feces were collected continuously and CO2 was collected for 7 days after dosing. The samples were analyzed for 14C and urine was also analyzed for [14C]sucrose. Animals (3/group) were killed 1, 3, 7, and 21 days after dosing, and tissues were collected and assayed for 14C. Tissue lipids were extracted, fractionated by high-pressure liquid chromatography, and analyzed for [14C]olestra by liquid scintillation. Animals fed poligeenan showed mucosal edema, congestion, ulceration, and fibrin deposition within the distal colon and rectum. Histology revealed inflammation, epithelial degeneration, and multifocal ulceration of the cecum, distal colon, and rectum. The gastrointestinal mucosae of nonpoligeenan fed animals were normal. No [14C]olestra was detected in liver lipids and no [14C]sucrose was found in the urine for any animal in the Normal or Compromised groups, indicating that intact olestra was not absorbed. The amount, distribution, and elimination of absorbed 14C did not differ between guinea pigs with normal and compromised gastrointestinal tracts. The poligeenan-treated animals displayed mucosal damage similar to that seen in human inflammatory bowel diseases; therefore, these results suggest that patients with inflammatory bowel conditions will not absorb olestra to any greater extent than normal healthy people.

A lysosomal storage disorder in the BALB/c mouse: bone marrow transplantation.

The morphological and biochemical consequences of transplanting affected bone marrow from donor BALB/c mice with a lysosomal storage disorder (BALB/c LSD) into normal recipient mice were studied. Bone marrow was removed from normal BALB/c and BALB/c LSD mice and transfused into normal BALB/c recipient mice four hours after the mice received 850 rads of irradiation. Tissues of the recipient mice were examined 240 days later. This study revealed that the defective cells that constituted the visceral lesions of BALB/c LSD could be transplanted to normal BALB/c mice by the use of bone marrow from affected BALB/c LSD homozygote; that the defective cells of BALB/c LSD proliferated and disseminated throughout the mononuclear phagocytic system of the recipient; that there were increases in cholesterol, sphingolipids, and cystine with decreases in sphingomyelinase and glucocerebrosidase activity in tissues of the recipients; and that the recipients survived substantially longer than BALB/c LSD homozygotes and their lifespan was compromised mainly by the secondary effects of irradiation. These lesions, although not as extensive as in homozygous BALB/c LSD, paralleled the lesions which develop in BALB/c LSD. Since the recipient mice were not compromised by the short life span (70 days) of the BALB/c LSD mice, they may be used to study the long-term chronic effects of these metabolic lesions.