The cytolytic effects of Salmonella enterica serovar Typhimurium on chicken heterophils.

Mixing of chicken heterophils and Salmonella enterica serovar Typhimurium resulted in a rapid disappearance of heterophils when examined by scanning electron microscopy and trypan blue dye exclusion test. This disappearance appeared to be caused by a rapid degranulation of heterophils.

Retroviral particles in neoplasms of Burmese pythons (Python molurus bivittatus).

Neoplastic diseases associated with retroviruses were diagnosed in four Burmese pythons (Python molurus bivattatus) from a single collection. Snake No. 1 was a 7-year-old female with recurrent undifferentiated mesenchymal round cell tumor (lymphosarcoma) of the oral cavity. At necropsy, similar neoplastic masses were evident in the uterus and ovary, and there was diffuse involvement of the spleen. Snake No. 2 was a 4.5-year-old female that was euthanatized because of complications following resection of a segmental colonic adenocarcinoma. Snake No. 3 was a 5-year-old female that was euthanatized because of a large transitional cell carcinoma of the right kidney. Snake No. 4 was a 19-year-old female that was euthanatized following recurrence of an intermandibular fibrosarcoma. Ultrastructural examination revealed few to numerous extracellular and intracellular (intravacuolar) type C-like retroviral particles in all tumors. Tumors were about 90-95 nm in diameter, with an electron-dense core and bilaminar external membrane. The relationship of the intraneoplastic viral particles to the etiology of the tumors is uncertain.

Feline vaccine-associated fibrosarcoma: an ultrastructural study of 20 tumors (1996-1999).

Twenty feline vaccine-associated sarcomas were examined by transmission electron microscopy. Tumors contained pleomorphic spindle cells, histiocytoid cells, and giant cells. Most tumors contained myofibroblasts, which had morphologic features similar to those of fibroblasts. These cells were further distinguished by subplasmalemmal dense plaques and thin cytoplasmic actin myofilaments organized as elongated bundles concentrated at irregular intervals forming characteristic dense bodies. Intracellular crystalline particulate material was found in 5 of the 20 tumors. Energy dispersive X-ray spectroscopy was used to identify the crystalline material within one tumor as aluminum-based. One tumor from a feline leukemia virus-infected cat contained budding and immature retroviral particles.

Partial characterization of retroviruses from boid snakes with inclusion body disease.

OBJECTIVE: To characterize retroviruses isolated from boid snakes with inclusion body disease (IBD). ANIMALS: 2 boa constrictors with IBD and 1 boa exposed to an affected snake. PROCEDURE: Snakes were euthanatized, and tissue specimens and blood samples were submitted for virus isolation. Tissue specimens were cultured with or without commercially available viper heart cells and examined by use of transmission electron microscopy (TEM) for evidence of viral replication. Reverse transcriptase activ ty was determined in sucrose gradient-purified virus. Western blotting was performed, using polyclonal antibodies against 1 of the isolated viruses. Specificity of the rabbit anti-virus antibody was evaluated, using an immunogold-labeling TEM technique. RESULTS: 3 viruses (RV-1, RV-2, and RV-3) were isolated. The isolates were morphologically comparable to members of the Retroviridae family. Reverse transcriptase activity was high in sucrose gradient fractions that were rich in virus. Polyclonal antibody against RV-1 reacted with proteins of similar relative mobility in RV-1 and RV-2. By use of immunogold labeling, this antibody also recognized virions of both RV-1 and RV-2. CONCLUSIONS AND CLINICAL RELEVANCE: A retrovirus was isolated from boid snakes with IBD or exposed to IBD. Western blot analysis of viral proteins indicated that viruses isolated from the different snakes were similar. Whether this virus represents the causative agent of IBD is yet to be determined. The isolation of retroviruses from boid snakes with IBD is an important step n the process of identifying the causative agent of this disease.

Microsporidial AIDS cholangiopathy due to Encephalitozoon intestinalis: case report and review.

Microsporidia are increasingly recognized as opportunistic infections in immunodeficient patients, predominantly patients with AIDS. The two microsporidia most commonly associated with disease in AIDS patients are Enterocytozoon bieneusi and Encephalitozoon intestinalis (previously known as Septata intestinalis). The most common clinical presentation of microsporidiosis in AIDS patients is diarrhea, most commonly caused by the Enterocytozoon bieneusi species. Encephalitozoon intestinalis is a recently described species that has been reported to cause disseminated human infection including cholangitis. We report a case of AIDS cholangiopathy that presented with abdominal pain and cholestatic liver tests. Ultrasound examination and ERCP revealed a picture of sclerosing cholangitis. Bile samples obtained at ERCP were negative for microsporidia; stool studies for microsporidia and cryptosporidia were also negative. No organisms were identified on routine light microscopy of the biopsy specimens from the duodenum, ampulla, and bile duct. E. intestinalis spores were demonstrated in the bile duct biopsies, by methylene blue and azure 11 staining and confirmed by electron microscopy. Albendazole therapy was successful in eradicating E. intestinalis with clinical improvement and improvement in CD4 count. However, the cholangiographic picture did not improve and repeat cholangiography revealed progressive bile duct injury. Albendazole therapy was delayed and may have been too late to prevent bile duct damage; the drug had to be approved by the US Food and Drug Administration for compassionate use. This is an unusual case of sclerosing cholangitis caused by an unusual organism and requiring biliary sphincterotomy and stent placement for progressive stricturing despite eradication of the infection.

Healthy cats are commonly colonized with "Helicobacter heilmannii" that is associated with minimal gastritis.

Gastric Helicobacter infection in healthy pet cats is not well characterized. We performed endoscopy with gastric biopsy on 15 healthy pet cats that were rigorously screened to exclude underlying or concurrent diseases that might affect Helicobacter colonization. Gastric mucosa biopsy specimens were examined by histology, culture, and PCR for the presence of Helicobacter infection and by histology for the presence of gastritis. Of 15 cats, all but 1 had gastric Helicobacter-like organisms (GHLOs) on examination by light microscopy, and in the one histologically negative cat, GHLOs were detected by PCR. Gastric inflammation was mild or was absent for all cats. No Helicobacter species were identified by culture. Analysis of the 16S rRNA sequence from Helicobacter strains from 10 cats showed that all bacteria were closely related to Helicobacter felis, although there was heterogeneity among the sequences. These results suggest that the gastric mucosa of healthy pet cats is commonly colonized with an uncultivated Helicobacter that is closely related to H. felis, is associated with little or no gastritis, and shows heterogeneity in its 16S rRNA sequence. The epithet "Helicobacter heilmannii" continues to be an appropriate working designation for these bacteria.

Epitheliocystis infection in cultured white sturgeon (Acipenser transmontanus): antigenic and ultrastructural similarities of the causative agent to the chlamydiae.

A mild to moderate branchial epitheliocystis infection was diagnosed in subyearling (11 months old, 250-300 g) white sturgeon (Acipenser transmontanus) from a private culture facility with a 4-8% mortality in the population. Infected branchial epithelial cells contained the coccoid to coccobacillary epitheliocystis organisms, which appeared as cytoplasmic inclusions composed of a fine, homogeneous, dense, basophilic, granular material. The infected cells were variably enlarged with spherical to oval profiles and were randomly distributed throughout the branchial epithelium. The cytoplasmic inclusions stained positive with Macchiavello stain but negative with Brown and Brenn, periodic acid-Schiff, and Gimenez stains. Expression of chlamydial antigen was demonstrated within the cytoplasmic inclusions using a standard peroxidase-antiperoxidase immunohistochemical technique. Three stages of coordinated intracellular development were recognized by electron microscopy. The reticulate bodies were oval to spherical and 0.4-0.8 x 0.5-1.4 microns but often exhibited a pleomorphic and convoluted appearance because of variable membrane invaginations and evaginations suggestive of uneven fission and budding. Separate host cells contained intermediate bodies that were spherical to oval and 0.2-0.4 x 0.3-0.6 microns although often observed in the process of apparent uneven division. The presence of a cap or plaque composed of hexagonally arrayed fibrillar surface projections was initially recognized in this stage. A homogeneous population of 0.3-0.4 microns oval elementary bodies were observed separately in individual host cells. This developmental stage had a single, dense, compact, eccentrically located cytoplasmic condensation that occurred opposite to the location of the cap of hexagonally arrayed fibrillar surface projections. Morphologic characteristics of the epitheliocystis organism in these white sturgeon were similar to those previously described in other teleosts and expands the species catalogue of epitheliocystis infection. Furthermore, the ultrastructural similarities to the chalmydiae and the immunohistochemical detection of chlamydial antigen provides further evidence that the epitheliocystis agent is related to members of the Chlamydiales. Although the infection was considered mild to moderate and could not be definitively attributed to the mortality in this population, the potential adverse impact of epitheliocystis infection on sturgeon culture should be considered especially in intensive fish culture operations.

Histopathology of transgenic mouse mammary tumors (a short atlas).

Mammary hyperplasias, dysplasias and tumors have been described in many strains of transgenic mice. Many of the transgenes produce characteristic disturbances of growth, development and neoplasia. The disturbances can now be classified into groups. A classification of transgenic tumors and an atlas illustrating some characteristic examples of common morphological changes in transgenic mammary tissues is provided.

Comparative pathology of mammary tumorigenesis in transgenic mice.

Mammary tumors arise in transgenic mice bearing growth factors, proto-oncogenes, oncogenes and tumor suppressor genes. The tumors arise from hyperplasias. The tumor natural history and histogenesis are oncogene specific. Interactions between oncogenes may impede or accelerate tumorigenesis.

Nonsecretory multiple myeloma in a dog: immunohistologic and ultrastructural observations.

A 12-year-old, female spayed Chihuahua was diagnosed with nonsecretory multiple myeloma on the basis of multiple osteolytic lesions, histological evidence of plasma cell infiltrate on a bone biopsy, and absence of a monoclonal protein on serum and urine electrophoresis. A 6-week course of prednisone therapy resulted in no clinical improvement and the dog was euthanized 2 weeks after presentation because of progressive neurological impairment. Bone marrow specimens were processed and stained for ultrastructural and immunohistologic evaluation. Staining with antisera to immunoglobulin (Ig) G, IgM, and IgA was negative. Tumor cells in both the pelvic and rib masses displayed prominent reactivity with an antibody specific for a canine beta 1 integrin similar to VLA-4; however, the tumor cells failed to stain with antibodies known to react predominantly with antigens on B-lymphocytes (major histocompatibility complex class II, CD45RA, and CD21) or T-lymphocytes (Thy-1). The tumor cells also failed to stain with an antibody specific for the beta-subunit (CD18) of the leukocyte integrins (D11/CD18). Ultrastructural studies performed on bone marrow specimens revealed a pleomorphic population of plasma cells with moderate amounts of rough endoplasmic reticulum, erythrophagocytosis, and lack of crystalline inclusions.

Enteritis in turkeys associated with an unusual flagellated protozoan (Cochlosoma anatis).

Outbreaks of enteritis associated with an unusual flagellated protozoan occurred in six California turkey flocks during the summer of 1992. Certain morphological and ultrastructural details of the parasite, which resembles Cochlosoma anatis, are illustrated with scanning and transmission electron micrographs. The flagellate attached to the intestinal mucosa by means of a sucker-like apparatus, and circular impressions of the sucker were created on the surface epithelium. Histological lesions were characterized by blunting and fusion of villi; cellular infiltration of the lamina propria with lymphocytes, plasma cells, histiocytes, and heterophils; and increased numbers of mitotic figures in crypt epithelium.

Experimental induction of hepatic lipidosis in cats.

The effect of long-term voluntary fasting on hematologic variables, biochemical profiles, and liver histologic findings was assessed in 15 obese cats (> 40% overweight). Clinical signs and laboratory results consistent with hepatic lipidosis were observed in 12 of 15 cats after 5 to 7 weeks of fasting, and were associated with 30 to 35% reduction of initial body weight. Histologic examination of successive liver biopsy specimens revealed that obesity was not associated with liver parenchymal lipid accumulation, but that fasting resulted in lipidosis in all 15 cats. The long-term fast was associated with an early (after 2 to 4 weeks of fasting) and significant (P < 0.05) reduction in serum urea, glucose, and albumin concentrations, and RBC mass. Fasting for 5 to 7 weeks was associated with a significant (P < 0.05) increase in hepatic-associated enzyme activities and in total and direct serum bilirubin concentrations. Significant (P < 0.05) changes in serum alkaline phosphatase developed as early as 3 weeks before the onset of hyperbilirubinemia. Except for development of hepatic lipidosis, cats appeared to tolerate the fast without other adverse effect. This study confirmed that long-term fasting may induce clinical hepatic lipidosis in obese cats. Fasting appears to induce a syndrome of hepatic lipidosis that is indistinguishable from feline idiopathic hepatic lipidosis and may be an appropriate model to study the pathophysiologic features and treatment of hepatic lipidosis.

Metastatic adenocarcinoma of a minor salivary gland in a cat.

Neoplasms derived from salivary glands are uncommon in domestic animals and descriptions of neoplasms derived from minor salivary glands are quite rare. A primary neoplasm derived from a minor salivary gland is described in a 13-year-old domestic shorthair cat. The oral neoplasm was locally invasive, and had metastasized to the regional lymph nodes and hilus of the lungs.

Isolation and partial purification of plasma membrane from porcine oocytes.

Egg plasma membrane (EPM) was isolated in comparatively large amounts from porcine slaughterhouse ovaries. Ovaries were minced, and the oocyte containing fluid was filtered to retrieve zona pellucidae-intact oocytes. The oocytes were homogenized and filtered again to remove zona pellucidae. The egg filtrate was subjected to differential centrifugation to remove membrane bound organelles and the remaining plasma membrane containing material was pelleted by ultracentrifugation. Plasma membranes were further separated from cellular material by sucrose density gradient centrifugation and were collected from portions of the gradient that correspond to the densities of plasma membrane. The purity of isolated plasma membranes was assessed by membrane marker enzyme analysis and transmission electron microscopy. Activities of the plasma membrane marker enzymes 5' nucleotidase and alkaline phosphatase increased from nondetectable levels in the egg filtrate to relatively high levels in the plasma membrane preparation. Marker enzymes for mitochondrial and lysosomal membranes fell from detectable levels in the egg filtrate to levels that were at the lower limits of the assays to detect in the final preparation. Evidence provided by binding of biotin-labeled EPM to capacitated sperm suggests that the isolated EPM retains its biological activity. The procedure presented here represents a novel method of isolating porcine egg plasma membranes for further study involving sperm-egg interaction.

Centrilobular distribution of acetaldehyde and collagen in the ethanol-fed micropig.

We established a new animal model of alcoholic liver disease in the micropig, a species that consumes ethanol voluntarily in the diet. Ten micropigs were pair-fed diets containing 40% of calories as ethanol or cornstarch with identical amounts of fat, protein and micronutrients for 12 mo. Liver histopathology in the ethanol-fed pigs included steatonecrosis in all five and interstitial and perivenous fibrosis in three. Electron microscopy showed Ito-cell transformation with perisinusoidal collagen accumulation. Acetaldehyde adducts were found by immunofluorescence in the centrilobular region and were focused in perivenous zone 3 of all ethanol-fed animals. Protein and triglyceride levels were increased, whereas vitamin A and iron levels were decreased in liver homogenates from ethanol-fed animals. Thus, in this new animal model of alcoholism, ethanol feeding produced the features of alcoholic liver disease concurrent with hepatic deficiency of selected nutrients. Histological and immunofluorescent studies provide in vivo evidence that perivenous collagen deposition is linked to ethanol metabolism and acetaldehyde production.

Ultrastructure of canine vasoformative tumors.

The transmission electron microscope was used to examine 20 spontaneous canine hemangiosarcomas or hemangiopericytomas in order to define their fine ultrastructural features, and to compare those features with descriptions of human counterpart neoplasms. From specimen to specimen the neoplasms examined showed considerable structural heterogeneity but, in composite, appeared similar to the prototype human tumors. These data suggest that the canine hemangiosarcoma and hemangiopericytoma might serve as comparative models for studies of the morphogenesis of vasoformative neoplasms.