Olaf R. Hedstrom

Pathology of Campylobacter jejuni abortion in sheep.

Campylobacter jejuni was inoculated intravenously into pregnant ewes on gestation days 114 and 123 to reproduce ovine abortion. All ewes aborted 7–12 days post-inoculation. High numbers of C. jejuni were isolated from ewe tissues (caruncle, bile, cecal feces), fetal tissues, and placenta. C. jejuni colonies were identified in caruncles and placenta by light microscopy and immunoperoxidase techniques. Histologically, inoculated ewes had a severe purulent endometritis with vasculitis. Placentas from inoculated ewes and field cases showed necrosis and purulent inflammation; however, placentas from inoculated ewes had large numbers of bacterial colonies compared to few bacteria found in field cases. Histologically, only one fetus from the inoculated ewes showed lesions (purulent bronchopneumonia), whereas all fetuses from field cases had a distinct bronchopneumonia, and one fetus showed multifocal hepatic necrosis. These results suggest that C. jejuni (serotypes Penner 1 and Lior 2) is an important abortifacient organism for sheep.

Meningoencephalitis in Mink Associated with a Sarcocystis Neurona-Like Organism

5. Hsu SM, Raine L, Farger H: 1981, Use of avidin-biotin-peroxidase-complex (ABC) in immunoperoxidase techniques: a comparison between the ABC and unlabeled antibody (PAP) procedure. J Histochem Cytochem 29:577-580. 6. Neer TM, Reavis DU: 1983, Craniopharyngioma and associated central diabetes insipidus and hypothyroidism in a dog. J Am Vet Med Assoc 182:519-520. 7. Patnaik AK, Nafe LA: 1980, Intracranial teratocarcinoma in a dog. Vet Pathol 17:764-769. 8. Ribas JL, Carpenter JL, Mena H, et al.: 1991, Central system meningioma in the dog: a review of 50 cases. J Neuropathol Exp Neurol 50:373. 9. Saunders LZ, Richard CG: 1952, Craniopharyngioma in a dog with apparent adiposogenital syndrome and diabetes insipidus. Cornell Vet 42:490-495. 10. Schulman FY, Carpenter JL, Ribas JL, Brum DE: 1992, Cystic papillary meningioma in the sella turcica of a dog. J Am Vet Med Assoc 200:67-69. 11. Valentine BA, Summers BA, de Lahunta A, et al.: 1988, Suprasellar germ cell tumors in the dog: a report of five cases and review of the literature. Acta Neuropathol 76:94-100. 12. Walsh JW: 1985, Suprasellar germinomas. In: Neurosurgery, ed. Wilkins WH, Rengachary SS, pp. 921-925. McGraw-Hill, New York, NY.

Localization of cytochrome P-450 in the head and trunk kidney of rainbow trout (Salmo gairdneri)☆

Mature, untreated rainbow trout display a marked sex difference in the level and activity of the P-450-dependent mixed-function oxidase system with males demonstrating higher levels than females. This difference is accentuated in the trunk kidney, is specific for endogenous substrates such as lauric acid and sex steroids, and is correlated with greater levels of the constitutive cytochrome P-450 isozyme, LM2. Using an immunohistochemical technique, the cellular localization of P-450 LM2 and P-450 LM4b, the major beta-naphthoflavone inducible isozyme, in the head and trunk kidney of male, female, and juvenile trout has been demonstrated. Immunostaining for P-450 LM2 was observed in the cytoplasm of cells in the second portion (P2) of the proximal tubules of both male and female trout. In male fish, staining appeared to be more intense and involved most of the P2 segments in a tissue section. In female fish, P2 staining was moderate and involved fewer segments. Low staining intensity for P-450 LM4b was observed in the cytoplasm of cells both in the first portion of the proximal tubules and in P2 of male and female fish. Sexual dimorphism was not apparent. The finding of greater amounts of P-450 LM2 in males and low levels of P-450 LM4b in untreated male and female trout confirms previous biochemical studies. Localization of P-450 isozymes in the proximal tubules is consistent with findings in mammalian species. Moderate immunostaining by anti-P-450 LM4b IgG also was observed in the interrenal cells of the head kidney of male, female, and juvenile trout.

Cytochrome P450 isozyme distribution in normal and tumor-bearing hepatic tissue from rainbow trout (Salmo gairdneri)

An immunohistochemical technique was used to localize the major constitutive cytochrome P450 isozyme, P450 LM2, and the major beta-naphthoflavone-inducible isozyme, P450 LM4b, in the livers of untreated and aflatoxin B1 (AFB1)-initiated, tumor-bearing rainbow trout. In hepatic tissue sections from untreated trout, no regular anatomical pattern within the hepatic parenchymal cells could be discerned for either isozyme. Immunostaining was observed for P450 LM2 along the sinusoidal border of some of the parenchymal cells, there was moderate staining within the cytoplasm of most cells, and there were focal areas of increased staining. There was intense, uniform immunostaining for P450 LM2 within the cytoplasm of the bile duct cells, in the endothelial lining of arterioles, and along the epithelial surface of the gall bladder. Staining for P450 LM4b in livers from untreated trout was barely detectable. In liver tissue sections from AFB1-treated tumor-bearing fish, P450 LM2 appeared to be reduced and P450 LM4b was absent in the hepatocellular carcinoma nodules. An apparent increase in immunostaining for P450 LM4b was observed in nonneoplastic cells juxtaposed next to neoplastic cells as well as in areas distant to the tumors. These results may indicate that the pattern of P450 isozymes is altered in nonneoplastic cells of tumor-bearing trout livers.

CULTURE OF CELLS FROM JUVENILE WORMS OF SCHISTOSOMA MANSONI

Tissue disruption methods were developed and serum-free cell culture media formulated for the maintenance in vitro of cells from juvenile worms (day 18 after infection) of Schistosoma mansoni. Cultures maintained viability for up to 6 mo when plated on a feeder layer of irradiated rat liver cells and survived primarily as clusters of small (2.5-4 microns diameter) cells with a high nuclear-to-cytoplasmic ratio and relatively few organelles identified by electron microscopy. Cultures synthesized a protein profile similar to that of intact worms, and the cell clusters maintained a time- and concentration-dependent contractile response to serotonin. Cells synthesizing DNA were detected by precursor incorporation and flow cytometry in cultures initially and also after several weeks in vitro, although the percentage of cells synthesizing DNA decreased with time. Efforts to identify peptide growth factor-responsive tyrosine phosphorylation were negative, and the overall amount of S. mansoni phosphotyrosine-containing proteins identified by western blot with anti-phosphotyrosine monoclonal antibody was much less than that found in a peptide growth factor-responsive mouse cell line.

Effect of vitamin B12 on performance and tissue selenium content in rats fed sub-toxic levels of selenite

The effects of vitamin B12 status on growth and tissue selenium distribution were studied in Sprague-Dawley rats chronically exposed to subtoxic levels of selenite. Vitamin B12 status was monitored by urinary methylmalonic acid excretion and by liver and plasma vitamin B12 levels. Selenite absorption was unaffected by dietary level of vitamin B12. A significant (P < 0.05) interaction of vitamin B12 and selenium was found on growth of rats fed vitamin B12 deficient or control diets. In vitamin B12 depleted rats, there were significant histologic changes in the liver that were characterized by micronodules and regeneration, bile duct reduplication, mild cirrhosis, necrosis of individual hepatocytes and other minor histologic changes. There was no gross or histologic evidence of liver toxicity in rats supplemented with vitamin B12. Rats pair-fed 9 mg/kg selenium with vitamin B12 had significantly lower liver and kidney selenium levels and significantly higher blood selenium levels compared to rats fed the diet without vitamin B12. These results are consistent with the hypothesis that vitamin B12 deficiency limits selenium methylation and excretion, resulting in higher tissue selenium levels and subsequent toxicity.

Ultrastructural, protein, and lipid changes in liver associated with chlordecone treatment of mice

Pretreatment of mice with chlordecone (CD) reduced hepatic accumulation of a subsequent dose of [14C]CD without significantly changing [14C]CD biotransformation. To determine if CD-induced changes in hepatic [14C]CD accumulation were coincident with altered cell composition, we examined the effects of CD on hepatic protein and lipid content, on fatty acid profiles of liver and kidney, and on the ultrastructure of hepatocytes. SDS-polyacrylamide gel electrophoresis detected an apparent CD dose-related increase in a microsomal protein with a molecular weight of about 23 kDa. Total liver or kidney lipid contents were not altered by CD but relative amounts of several hepatic fatty acids were changed. CD caused marked hepatic mitochondrial swelling, increased amounts of endoplasmic reticulum, apparently increased numbers of peroxisome-like structures, and decreased numbers of lipid droplets in cytoplasm of hepatocytes. Numbers of lipid droplets were not decreased in perisinusoidal fat storage cells. In addition, the numbers of cytoplasmic lipoprotein vesicles were apparently increased in some hepatocytes. Overall these changes indicated an increased hepatocyte secretory activity and suggested that CD changed hepatocellular lipid transport, storage, and metabolism pathways.

Multifocal polioencephalomyelomalacia in Simmental calves with elevated tissue aluminum and decreased tissue copper and manganese

A spectrum of related malacic disorders called Simmental multifocal symmetrical encephalopathy have been reported in Simmental and Simmental crossbred cattle in Canada, Australia, and New Zealand. 3 The cause of this condition is unknown. We describe multifocal polioencephalomyelomalacia in Simmental calves reared in Oregon, USA, with morphologic lesions similar to those described in Simmental multifocal symmetrical encephalopathy. These calves also had elevated tissue concentrations of aluminum and deficient hepatic copper and manganese concentrations, which may be related to this condition. Four 7-month-old bull calves from a herd of 135 Simmental cows developed paresis, ataxia, and knuckling over of both hind limbs that progressed over a 2-month period to inability to rise. During the previous 2 years, 3 calves similarly affected died. Affected calves remained bright and alert and maintained the ability to suckle. Antibiotic therapy was not beneficial, and complete blood count and serum chemistry profiles were normal in the 3 calves evaluated. Two of the calves were presented to the Oregon State Veterinary Diagnostic Laboratory for postmortem examination. Significant lesions were limited to the central nervous system, with secondary mild symmetrical atrophy of the rear limb muscles. Grossly, oblong to circular foci of malacia of various sizes (up to 1 cm diameter) were seen throughout the gray matter of the brain. Similar gross lesions were within the gray matter of the lumbar spinal cord in 1 of the calves. Microscopically, these lesions were cavitated and were composed almost entirely of necrotic debris (Fig. 1). Scattered viable neuroglial cells were within these foci but neurons were not observed. Microgliosis, astrocytosis (including gemistocytes), active neuronal necrosis, ischemic neuronal changes, and vasculitis were not observed. Vessels were prominent within the lesions, principally because of hypertrophy of endothelial nuclei. Neurofibrillary tangles and/or extensive demyelination were not observed in multiple Bodain- and Luxol fast blue-stained histologic sections. The histopathologic changes were markedly uniform throughout the affected foci. The distribution of brain lesions was essentially identical in the 2 affected calves. The gray matter lesions of the brain involved numerous nuclei but invariably extended beyond nuclear boundaries. Individual lesions often involved more than 1 nucleus with some extension into the adjacent white

Effect of dietary fluoride on selenite toxicity in the rat

Three factorial experiments were conducted to determine if high dietary fluoride (F) would inhibit selenite toxicity in rats. Initially, three levels of selenite (0.05, 3, and 5 mg/kg diet) were matched against three levels of F (2, 75, and 150 mg/kg diet). Fluoride failed to prevent the depressive effect of selenite on 8-wk food intake and body wt gain. Selenium (Se) concentration of plasma and kidney and enzymatic activity of whole blood glutathione peroxidase (GSH-Px) were also unaffected by F. Liver Se concentration, however, was slightly (12%) but significantly (p<0.025) reduced when the highest F and Se levels were combined. Fluoride (150 mg/kg) appeared to reduce liver selenite toxicity (5 mg/kg). Therefore, further study focused on liver histology with treatments that eliminated the middle levels of selenite and F. Fluoride prevented the hepatic necrosis seen in selenite-toxic rats. Similar histological lesions were not observed for kidney or heart. Fluoride partially (26%) but significantly (p<0.025) reduced thiobarbituric-reactive substances in selenite-toxic rats, but there was no F effect on intracellular distribution of liver Se, glutathione levels in liver and kidney, or on liver xanthine oxidase activity. Overall, the protective effect of F on selenite toxicity appears to be confined to liver pathology. The exact mechanism for this effect, however, remains unclear.

Measurement of IgG Concentration in Ovine Fetal Fluids: A Useful Diagnostic Test

The Veterinary Diagnostic Laboratory at Oregon State University received 172 aborted ovine fetuses during the 1985–1987 lambing seasons; from 120 of these, body fluids were evaluated for IgG levels. Fifty-two (43%) of the fetal fluids had immunoglobulin G (IgG) levels greater than 15 mg/dl. Forty-five (87%) of the fluids with elevated IgG levels were confirmed or presumed toxoplasma or Chlamydia abortions. A mean fetal fluid IgG concentration of 111.5 ± 78 mg/dl was found for the 26 toxoplasma abortions; for the 19 Chlamydia abortions, a mean IgG concentration of 109 ± 91 mg/dl was found. Antibody titers equal to or greater than 1:40 against Toxoplasma gondii were detected in 23 fetal fluids. Fetal fluid IgG concentration less than 15 mg/dl was found to be associated with bacterial organisms (i.e., Campylobacter sp.) as the confirmed or presumed cause of abortion. These results suggest that measurement of fetal fluid IgG concentration is a useful, supportive diagnostic test in determining the cause of ovine abortion, and should be included as a routine laboratory procedure for ovine abortion diagnosis.