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O Evensen

Publications and source records attributed to O Evensen.

31 records · Page 2Linked to original sources
PubMed1994

Effect of injected yeast glucan on the activity of macrophages in Atlantic salmon, Salmo salar L., as evaluated by in vitro hydrogen peroxide production and phagocytic capacity.

A prepared polysaccharide from the cell wall of yeast, M-Glucan, has previously been demonstrated to have immunostimulatory effects in salmonids as observed by enhanced in vivo non-specific disease resistance in Atlantic salmon, Salmo salar L., and increased in vitro bactericidal activity of rainbow trout, Oncorhynchus mykiss (Walbaum), macrophages. In the present study M-Glucan was injected intraperitoneally into Atlantic salmon and the effect on core components in the non-specific part of the immune system was observed. The hydrogen peroxide (H2O2) production of isolated head kidney macrophages from glucan-injected fish was measured 3 and 6 weeks after M-Glucan treatment and was increased at both time-points upon phorbol myristate acetate-(PMA) triggering. Without PMA triggering the difference was only significant 3 weeks after glucan injection when compared to a control group injected with saline. In a phagocytic assay with macrophages and Vibrio salmonicida the initial uptake of bacteria was elevated at both 3 and 6 weeks after glucan treatment. There was no significant difference when uptake of another fish pathogenic bacteria, Renibacterium salmoninarum, was studied. Treatment of Atlantic salmon with M-Glucan also resulted in enhanced serum lysozyme activity in week 3 of the experimental period. The results indicate that M-Glucan elevates the activity of the non-specific part of the immune system and the use of M-Glucan as an immunostimulant is discussed.

Animals↗
PubMed1993

An immunohistochemical study on the cytogenetic origin of pulmonary multinucleate giant cells in porcine dermatosis vegetans.

The origin of pulmonary multinucleate giant cells (MGC) in porcine dermatosis vegetans was studied in six Norwegian Landrace pigs ages 4 (male), 5 (female), 6 (female), 10 (female), and 12 (one male, one female) weeks, using an avidin biotin peroxidase and alkaline phosphatase complex immunohistochemical method on sections of formalin- and ethanol-fixed and frozen tissue specimens. Well-characterized, commercially available antisera/monoclonal antibodies to keratin, vimentin, lysozyme, a monocytic antigen, and a myelomonocytic antigen were used. The immunoreactivity to intermediate-sized filaments in MGC was negative for keratins and positive for vimentin. In addition, a positive reaction was found in alveolar macrophages, chondrocytes, fibrocytes, alveolar lymphocytes, and granulocytes in ethanol-fixed tissue. Marked masking was observed in formalin-fixed tissue. Antilysozyme antiserum gave a positive cytoplasmic reaction in alveolar macrophages and MGC, although the reaction was variable in ethanol-fixed tissue. In trypsinized formalin-fixed tissue, a moderate and more consistent cytoplasmic reaction was observed in alveolar macrophages and MGC. Two monoclonal antibodies that identify human cells of the MMS, EMB 11 and Mac 387, were negative for EMB 11 in ethanol-fixed and frozen sections, whereas Mac 387 showed a positive and specific cytoplasmic immunoreaction in alveolar macrophages and small MGC in ethanol- and formalin-fixed tissue. Pulmonary MGC in dermatosis vegetans are derived from mesenchymal cells, and substantial evidence is provided in support of a monocyte/macrophage origin based on a positive reaction for lysozyme and a myelomonocytic antigen. The importance of adequate fixatives for immunohistochemical demonstration of cell-specific markers is clearly shown.

Animals↗
PubMed1993

The identification of equid herpesvirus 1 in paraffin-embedded tissues from aborted fetuses by polymerase chain reaction and immunohistochemistry.

Paraffin-embedded organ samples from 28 aborted fetuses and three foals, partly archival and partly sampled in 1991, were examined by polymerase chain reaction (PCR) and immunohistochemistry for the presence of DNA and antigens, respectively, specific for equine herpesvirus 1 (EHV-1). Virologic examination had been performed on 23 of the aborted fetuses. DNA fragments specific for EHV-1 were identified by PCR, and EHV-1 antigens were identified in situ by immunohistochemistry, with an agreement between the methods of 94% (kappa = 0.85). Compared with virus isolation, PCR agreement was 87% (kappa 0.69), and IH agreement was 82% (kappa = 0.47). These results showed that there was moderate to almost perfect agreement among the different methods and that PCR and immunohistochemistry are powerful tools for the identification of EHV-1 in paraffin-embedded tissues. The techniques give more rapid results than virus isolation and also detect inactivated virus, which are not identified by standard virus isolation. These techniques also make retrospective studies possible.

Abortion, Veterinary↗
PubMed1992

A study of tobacco carcinogenesis XLVIII. Carcinogenicity of N'-nitrosonornicotine in mink (Mustela vison).

During tobacco processing and smoking, nicotine and nornicotine give rise to N'-nitrosonornicotine (NNN), a highly abundant, strong carcinogen. NNN is known to exert carcinogenic activity in mice, rats and hamsters. Major target organs for NNN carcinogenicity in the rat are the esophagus and the nasal mucosa, and in the Syrian golden hamster trachea and nasal mucosa. In comparison with the rat, the mink (Mustela vison) has a markedly expanded nasal mucosa. Therefore, we explored in this study whether the mink could serve as a non-rodent model for nasal carcinogenesis using NNN as the carcinogen. Twenty random-bred mink, beginning at the age of 3 weeks, received twice weekly s.c. injections of NNN, a total dose of 11.9 mM per animal over a 38 week period. All of the 19 mink at risk developed malignant tumors of both the respiratory and the olfactory region of the nose within 3.5 years. In most animals the malignant tumors, primarily esthesioneuroepithelioma, invaded the brain. Remarkably, NNN induced no other tumors in the mink. None of the control animals developed nasal tumors nor tumors at other sites during the 3.5 years of the assay. The historical data from the farm did not reveal any spontaneous occurrence of nasal tumors in mink at any age. This study supports the concept that NNN is a proven carcinogen for multiple species of mammals and that the mink can serve as a non-rodent, non-inbred animal model for nasal carcinogenesis, especially since NNN induces only tumors in the nasal cavity in this species and not at other sites, as it does in mice, rats and hamsters.

Animals↗
PubMed1992

An ultrastructural and cytochemical study of the pulmonary lesions and multinucleate giant cells in porcine dermatosis vegetans.

The pulmonary lesions and multinucleate giant cell formations in porcine dermatosis vegetans were studied ultrastructurally and cytochemically in seven affected pigs that ranged from one to 120 days of age. At birth, no pulmonary lesions were observed. By seven days of age, there was a moderate infiltration of monocytes/macrophages in the alveoli and interstitium. These changes progressed, and by two weeks of age there was pronounced infiltration of macrophages and lymphocytes in the alveoli. Close apposition of macrophages and lymphocytes was observed, and cellular contact was demonstrated. By three to four weeks of age, small aggregates with epithelioid cells, macrophages, and lymphocytes resembling granulomas were present. In an older pig, aged four months, the inflammatory changes waned. Large macrophages, and large and small multinucleate cells shared common morphological characteristics of cytoplasm endowed with organelles, primary and secondary lysosomes, Golgi profiles, and granular endoplasmic reticulum. Cytochemically, macrophages and MGCs were positive for acid phosphatase. The present study showed that the initial pulmonary changes share morphological characteristics with a granulomatous inflammatory response, and evolve into small granulomas with macrophages, epithelioid cells and lymphocytes. Morphologically, these changes share characteristics with epithelioid cell granulomas. Macrophages and MGCs share common ultrastructural traits, and are positive for acid phosphatase. MGCs seem to evolve in the course of the granulomatous inflammatory response and are probably of monocyte/macrophage origin.

Acid Phosphatase↗
PubMed1991

A morphological study of the gross and light microscopic lesions of infectious anaemia in Atlantic salmon (Salmo salar).

Infectious anaemia in Atlantic salmon (Salmo salar) was studied by recording gross and light microscopic changes, and the development of lesions was studied in relation to haematocrit values. Gross lesions were characterised by ascites formation, congestion and enlargement of liver and spleen, congestion of the foregut and petechiae in the peritoneum. Histologically, lesions were demonstrated in the liver, being characterised by congestion in early stages (that is, haematocrit values around 25), dilatation of the sinusoids, and in later stages (haematocrit values 25 to 15) formation of blood-filled spaces bearing morphological resemblance to peliosis hepatis. At low haematocrit values (around 10), these changes comprised large areas of the liver parenchyma, that is, blood-filled areas coalesced, presenting islets of degenerate and necrotic hepatocytes. At this stage, haemorrhagic necroses were found. Spleen and kidney lesions were characterised by congestion. In the foregut, congestion and bleeding in lamina propria were observed. Liver lesions became more disseminated and severe with decreasing haematocrit values. Hypoxia due to anaemia alone cannot fully explain the development of the liver lesions.

Anemia↗
PubMed1991

Inoculation of infectious pancreatic necrosis virus serotype Sp did not cause pancreas disease in Atlantic salmon (Salmo salar L.).

Atlantic salmon were selected from a fish farm with no previous record of pancreas disease (PD) or infectious pancreatic necrosis virus (IPNV) infection. Groups of fish were inoculated with either IPNV (strain Sp) from cell culture, organ material from fish with PD or control material as phosphate-buffered saline (PBS). Virological, histological and immunohistochemical examinations were carried out throughout the experiment. None of the fish died or showed clinical symptoms of PD. Histological examination revealed no pathological changes, and immunohistochemical studies were negative. Virus was isolated only sporadically from the group inoculated with organ material, whereas it was isolated consistently from the group inoculated with virus propagated in cell culture, as well as from in-contact control fish after the first week. In a latent carrier test, changes were entirely lacking in the first mentioned group, and were only slight in the last mentioned group. The data suggest that PD is not a transmissible disease, and that IPNV isolated from a PD outbreak does not play any part in the etiology of this disease.

Animals↗
PubMed1990

Immunohistochemical identification of infectious pancreatic necrosis virus in paraffin-embedded tissues of Atlantic salmon (Salmo salar).

Infectious pancreatic necrosis virus serotype Sp was identified by immunohistochemistry in formaldehyde-fixed and paraffin-embedded tissue of Atlantic salmon (Salmo salar). The immunoreaction was present in degenerating and necrotic cells in exocrine pancreatic cells. Cross reactions were observed with rabbit antisera against serotypes Sp, Ab, and VR-299 in neutralization tests and western blotting. Immunohistochemically, only Sp antiserum produced positive immunostaining to Sp antigens, whereas antisera to serotypes Ab and VR-299 were negative.

Animals↗
PubMed1990

A sequential light microscopic study of the pulmonary lesions in porcine dermatosis vegetans.

The sequential pulmonary changes in dermatosis vegetans were studied in pigs aged one, seven, 14, 17, 21 and 28 days, and two and a half, four and 12 months. At one day old the lung tissues appeared normal. At seven days old there was a moderate infiltration of mononuclear inflammatory cells in the alveolar structures, and proliferation of type II pneumocytes was also observed. At 14 and 17 days old the alveolar structures were intensely infiltrated with mononuclear inflammatory cells. At 21 days old, loosely arranged epithelioid and multinucleate giant cell granulomas appeared, and there was a proliferation of alveolar epithelial cells. By four and 12 months old the inflammatory changes diminished, and small granulomas and moderate alveolar fibrosis were present. The initial lesions were characterised by an alveolitis, developing into loosely arranged granulomas by four months old, and persisting to the age of 12 months. These observations suggest that the interpretation of the lung changes and the disease in general should be revised.

Animals↗
PubMed1989

Myofibre changes and capsule formation in mice infected with different strains of Trichinella.

Mice were infected with 4 strains of Trichinella with the purpose of describing muscle changes (M. Gastrocnemius, diaphragma) by light and electron microscopy, paying particular attention to capsule formation in a polar bear isolate (T. no. 13). No differences in myofibre changes or capsule formation were observed between the different strains by light microscopy at 21 and 60 days post infection. Ultrastructural studies of meat samples 60 day post infection with T. no. 13 revealed active capsule formation in muscle fibres, characterized by protrusions and invaginations of the sarcolemma. Basal lamina-like material was located close to the sarcolemma and in a lattice-like pattern in the capsule matrix. T. no. 13 seems to have a migratory pattern similar to the other strains examined and induces muscle fibre changes undiscernible from those of the 3 other strains. Infected muscle cells are considered to be involved in capsule formation.

Animals↗
PubMed1988

Non-neoplastic pulmonary multinucleate giant cells. Comparative study of multinucleate giant cells in porcine dermatosis vegetans and other polykaryocytic conditions.

Pulmonary multinucleate giant cells (MGCs) in porcine dermatosis vegetans (DV) were compared with virus-induced and inflammatory-associated MGCs, with particular attention to mechanisms involved in the formation of such cells. Ultrastructurally, pigs with DV showed numerous pulmonary MGCs with transversely-sectioned interdigitating microvillous structures. Microvilli were observed closely apposed to type-II pneumocytes and with morphological characteristics of membrane bridge formation. Rabbits infected with Mycobacterium bovis exhibited multiple pulmonary granulomas with prominent MGC formation 14 days after infection. Close apposition between MGCs and small macrophages and membrane bridge formation were demonstrated ultrastructurally. Pulmonary changes in calves infected with bovine respiratory syncytial virus (BRSV) included lobular consolidation and intense infiltration of inflammatory cells into the bronchial, bronchiolar and alveolar walls. Proliferation of bronchiolo-alveolar epithelial cells was prominent, but syncytiae were only occasionally demonstrated. This study of the morphological characteristics of MGCs is related to the present knowledge of mechanisms involved in membrane fusion and allows for an interpretation of an active fusion process involved in the formation of MGCs in porcine DV.

Animals↗