Clinicopathologic features of a systemic coronavirus-associated disease resembling feline infectious peritonitis in the domestic ferret (Mustela putorius).

From 2002 to 2007, 23 ferrets from Europe and the United States were diagnosed with systemic pyogranulomatous inflammation resembling feline infectious peritonitis (FIP). The average age at the time of diagnosis was 11 months. The disease was progressive in all cases, and average duration of clinical illness was 67 days. Common clinical findings were anorexia, weight loss, diarrhea, and large, palpable intra-abdominal masses; less frequent findings included hind limb paresis, central nervous system signs, vomiting, and dyspnea. Frequent hematologic findings were mild anemia, thrombocytopenia, and hypergammaglobulinemia. Grossly, whitish nodules were found in numerous tissues, most frequently the mesenteric adipose tissue and lymph nodes, visceral peritoneum, liver, kidneys, spleen, and lungs. One ferret had a serous abdominal effusion. Microscopically, pyogranulomatous inflammation involved especially the visceral peritoneum, mesenteric adipose tissue, liver, lungs, kidneys, lymph nodes, spleen, pancreas, adrenal glands, and/or blood vessels. Immunohistochemically, all cases were positive for coronavirus antigen using monoclonal antibody FIPV3-70. Electron microscopic examination of inflammatory lesions identified particles with coronavirus morphology in the cytoplasm of macrophages. Partial sequencing of the coronavirus spike gene obtained from frozen tissue indicates that the virus is related to ferret enteric coronavirus.

Myofasciitis in the domestic ferret.

Since late 2003, an inflammatory disease of muscle and fascia has been diagnosed in several ferrets at Northwest ZooPath, and this report describes the condition in 17 ferrets. It is a disease of young ferrets, characterized by rapid onset of clinical signs, high fever, neutrophilic leukocytosis, treatment failure, and death (or euthanasia). Gross lesions include atrophy of skeletal muscle; red and white mottling and dilatation of the esophagus; and splenomegaly. Histologically, moderate to severe suppurative to pyogranulomatous inflammation is in the skeletal muscle and the fascia at multiple sites, including esophagus, heart, limbs, body wall, head, and lumbar regions. Myeloid hyperplasia of spleen and/or bone marrow also is a prominent feature. Ultrastructural lesions include mitochondrial swelling, intracellular edema, disruption of myofibrils and Z bands. Bacterial and viral cultures, electron microscopy, immunohistochemistry, and polymerase chain reaction were negative for a variety of infectious agents. The clinical presentation and distribution of lesions suggests that polymyositis in domestic ferrets is likely a distinct entity. The etiopathogenesis if this condition is not known.

Calcium-independent, tyrosine phosphorylation-dependent effects of serum on the morphology of cultured neurohypophysial astrocytes.

Activation of adenylate cyclase induces cultured neurohypophysial astrocytes (pituicytes) to change from a protoplasmic, nonstellate form to a stellate form. Stellation is inhibited and reversed (destellation) by serum. The objective of the present studies was to examine the roles of Ca2+ and tyrosine phosphorylation in mediating these morphological changes. The effects of forskolin (to induce stellation) and serum (to inhibit and reverse stellation) were not affected by replacement of Ca2+ with Co2+ in the medium or by treatment of cultures with thapsigargin. However, genistein, a specific inhibitor of tyrosine kinase(s), significantly reduced the effect of serum on forskolin-induced stellation. Also, dephostatin, a specific inhibitor of tyrosine phosphatase, inhibited forskolin-induced stellation. In contrast, genistein did not have a dramatic effect on serum-induced destellation. The data demonstrate that morphological changes exhibited by cultured pituicytes are independent of Ca2+ but may be modulated by the activity of tyrosine kinase(s) and phosphatase(s).

Morphological plasticity of cultured astrocytes derived from the subfornical organ of the adult rat.

The morphological plasticity of astrocytes from the subfornical organ of the adult rat has been examined using an explant culture preparation. Astrocytes migrate out of the explant and form a monolayer of amorphous, non-stellate cells. This non-stellate form was maintained when cultures were incubated in a HEPES buffered salt solution (HBSS) for 50 minutes. The fraction of cells that was stellate in these cultures was significantly increased when cultures were incubated in HBSS supplemented with forskolin (5 microM; but not 1,9-dideoxyforskolin) or with nitroprusside (10-100 microM) indicating that elevation of intracellular cAMP or cGMP mediates stellation. The stellation responses induced by forskolin and by nitroprusside were blocked by inclusion of serum (0.5%) or of LY83,583 (10 microM), an inhibitor of soluble guanylate cyclase, in the incubation medium. The relevance of the data to neuroglial plasticity in the subfornical organ in vivo is discussed.

Serum uncouples elevation of cyclic adenosine monophosphate concentration from cyclic adenosine monophosphate dependent morphological changes exhibited by cultured pituicytes.

Cultured pituicytes (neurohypophysial astrocytes) are normally flat amorphous cells when incubated (90 min) in a HEPES balanced salt solution (HBSS) but become stellate when incubated in HBSS supplemented with forskolin. This stellation process is attenuated by serum (0.5% vol/vol). The experiments described here were designed to determine whether serum attenuates stellation by modulation of the intracellular cyclic adenosine monophosphate (cAMP) concentration or some other mechanism. It was observed that the effect of serum on forskolin-induced stellation was not affected by pertussis toxin (100 ng/ml) and that serum also inhibited stellation induced by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX; 100 microM). Further, serum inhibited stellation induced by the membrane permeable cAMP analog 8-bromo cAMP (150 microM). These results indicate that although an increase of intracellular cAMP concentration is necessary for pituicyte stellation, an increase of intracellular cAMP concentration may be decoupled from stellation.

Nitric oxide induces morphological changes in cultured neurohypophysial astrocytes.

Cultured pituicytes, derived from the neurohypophysis of adult rats, have previously been reported to change from a non-stellate form to a stellate form when incubated in medium containing a beta-adrenoreceptor agonist. This study was designed to determine whether the same morphological change could be induced by direct activation of adenylate cyclase or of soluble guanylate cyclase. The fraction of stellate cells was normally low (< 0.25) when the pituicytes were incubated (90 min) in a HEPES buffered salt solution (HBSS); most pituicytes had an amorphous protoplasmic appearance. The fraction of stellate cells was significantly increased when pituicytes were incubated in HBSS supplemented with isoproterenol (10 microM) or forskolin (5 microM) or with either of the nitric oxide donors nitroprusside (10-25 microM) and 3-morpholinosydnonimine (SIN-1; 10 microM). The effect of forskolin was mimicked by 8-bromo cyclic AMP, a membrane permeable analog of cyclic AMP, but not by the inactive forskolin analog 1, 9 dideoxyforskolin. The effect of nitroprusside was blocked by methylene blue, an inhibitor of soluble guanylate cyclase, and was mimicked by 8-bromo cyclic GMP, a membrane permeable analog of cyclic GMP. These results demonstrate that activation of adenylate cyclase and also of soluble guanylate cyclase can induce pituicytes to undergo morphological changes in vitro. The data suggest that the activity of both enzymes may be important in control of the plastic relationship that exists between neuronal and glial elements in the neurohypophysis in vivo.

Serum modulates cyclic AMP-dependent morphological changes in cultured neurohypophysial astrocytes.

The effects of serum on the morphological plasticity exhibited by pituicytes in explant cultures of the neurohypophysis of adult rats have been examined. Cultured pituicytes are normally nonstellate, protoplasmic, amorphous cells (< 25% are stellate with a distinct cell body and phase bright processes). After incubation (90 min) of pituicyte cultures in a HEPES buffered salt solution (HBSS) supplemented with isoproterenol or forskolin, the fraction of stellate pituicytes significantly increased. The increase in the fraction of stellate cells induced by isoproterenol was not reversed by subsequent incubation in isoproterenol-free HBSS for 90 min. In contrast, after stellation was induced in cultures by exposure to forskolin (90 min), the fraction of stellate cells was significantly reduced if these cultures were incubated in forskolin-free, serum (0.5%) supplemented HBSS for the same duration. Serum also blocked the increase in the fraction of stellate pituicytes induced by forskolin. These experiments suggest that serum components may have a significant role in controlling the plasticity of neuroglial relations in the neurohypophysis previously demonstrated in vivo.