Hypoalgesic behaviors of P/Q-type voltage-gated Ca2+ channel mutant mouse, rolling mouse Nagoya.

Rolling mouse Nagoya (tg(rol)) is a spontaneously occurring P/Q-type voltage-gated Ca2+ channel (VGCC) mutant mouse. A P/Q-type VGCC with the tg(rol) mutation has lower voltage sensitivity of activation, and mice with a homozygous genotype (tg(rol)/tg(rol)) but not with a heterozygous genotype (tg(rol)/+) show impaired motor coordination of the hind limbs. To investigate the roles of P/Q-type VGCC in pain sensing mechanisms, behavioral responses of adult tg(rol) mice to thermal, mechanical and chemical nociceptive stimuli were examined by the plantar, tail-flick, von Frey and formalin tests. The latency of the withdrawal response to thermal stimuli in the plantar or tail-flick tests was significantly longer in tg(rol)/tg(rol) mice than in tg(rol)/+ and wild-type (+/+) mice, and in tg(rol)/+ mice than in +/+ mice. The withdrawal response to mechanical stimuli in the von Frey test was lower in tg(rol)/tg(rol) mice than in +/+ mice. Although the licking time during the first 5 min after the formalin injection was similar among all of the three genotypes, that during 5-60 min was significantly shorter in tg(rol)/tg(rol) mice than in tg(rol)/+ and +/+ mice, and in tg(rol)/+ mice than in +/+ mice. Artificial inflammation induced by injection of complete Freund's adjuvant (CFA) into a hind paw significantly enhanced the withdrawal response recorded in the plantar and von Frey tests regardless of the mouse genotype. The CFA-enhanced response in the tg(rol)/tg(rol) mice was similar to the response in +/+ mice without the CFA injection. These results suggest that tg(rol) mutant mice show hypoalgesic responses caused by a lower sensitivity to nociceptive thermal, mechanical and chemical stimuli. It is concluded that the P/Q-type VGCC has a pro-nociceptive role and that the tg(rol) mutant mouse may be a useful tool to investigate the role of the P/Q-type VGCC in pain sensing mechanisms.

Distribution of rabbit haemorrhagic disease virus RNA in experimentally infected rabbits.

Adult rabbits were inoculated with liver homogenate from a rabbit that died in a Japanese outbreak of rabbit haemorrhagic disease (RHD). All experimentally infected rabbits died with typical clinical, gross and histological findings of RHD. Distribution of RHD virus in tissues of the infected rabbits was studied by non-isotopic in-situ hybridization. Both viral plus- and minus-strand RNAs were detected within the cytoplasm of hepatocytes, Kupffer cells and splenic and alveolar macrophages, mainly in morphologically intact cells. Strand-specific reverse transcriptase-polymerase chain reaction also demonstrated viral minus-strand RNA as well as plus-strand RNA in the liver, lung and spleen of infected rabbits. These results suggest that viral replication occurs not only in hepatocytes but also in macrophages. The infected macrophages may contribute to viral dissemination in RHD.

Extrahepatic bile duct malformation causing intrahepatic cholangiocellular proliferation with fibrosis in broiler chickens.

Malformation of the extrahepatic biliary tracts was observed in six of 88 enlarged, firm and discoloured livers collected at a slaughterhouse. Histologically, the six livers were characterized by diffuse cholangiocellular proliferation with fibrosis, extremely similar to the condition induced by bile duct ligation. These findings suggested that some cases of cholangiohepatitis in chickens are caused by biliary malformations with bile stasis.

Ganglion cysts in a juvenile dog.

Ganglion cysts were diagnosed in a 4-month-old male Afghan Hound. Grossly, the subcutaneous ovoid cysts around the caudal right elbow joint and left ischiatic tuberosity had abundant mucinous fluid and internal folding. The lesions recurred twice around the elbow joint after surgical removal. Neither cyst communicated with the joint cavity. Histologically, the cyst wall consisted of inner myxomatous and outer immature connective tissue. Some parts of the cyst wall had various stages of myxoid metaplasia of collagen tissue leading to new cyst formation. Ultrastructural study revealed that cells in the myxoid metaplastic lesion had well-developed cytoplasmic secretory elements, including abundant rough endoplasmic reticulum, Golgi apparatus, and many smooth-walled vesicles. These ganglion cysts apparently resulted from the metaplasia of fibroblasts to secreting cells.

Lead poisoning in wild waterfowl in Japan.

We collected 430 harvested ducks (Anas sp. and Aythya sp.) from nine prefectures in Japan between 1994 and 1997. Fifteen (4%) of 363 birds harvested during and after hunting seasons had one lead pellet each in the proventriculus and gizzard. In addition, 32 (34%) of 93 swans (Cygnus sp.) and two of 14 geese (Anser sp.) found dead from various wetlands had lesions consistent with lead poisoning. One to nine swans suspected of having toxicosis from ingestion of lead shot were found dead each year. Twenty-seven (84%) of the 32 lead-exposured swans were found in Hokkaido Prefecture. We concluded that lead poisoning is still a serious threat to waterfowl in Japan and that there is considerable need for environmental improvement concerning this problem.

Neurotoxic effects of 2,5-hexanedione on normal and neurofilament-deficient quail.

The neurotoxic effects of 2,5-hexanedione (2,5-HD) were investigated using neurofilament (NF)-deficient (Quv) Japanese quail in comparison with normal Japanese quail. Both Quv and normal Japanese quail were inoculated intraperitoneally with 350 mg/kg/day 2,5-HD for 6 consecutive wk. The results of 2,5-HD exposure differed substantially between the 2 strains of Japanese quail. The 2,5-HD-exposed normal quail showed leg paralysis about 4 wk after initiation of dosing. Some treated normal quail fell into dysstasia and died of nutritional disturbances. Histologically, 2,5-HD-treated normal quail had NF-rich axonal swellings and degeneration in the distal parts of the peripheral nerves, spinal cord, and cerebellar peduncles. In contrast, 2,5-HD-injected Quv quail showed tonic convulsion, ataxia gait, severe quivering, and excitation about 2-3 days after administration. Some treated Quv birds died immediately after systemic tonic convulsion, probably because of asphyxia. Although all treated Quv quail showed neurologic signs, there were no recognizable 2,5-HD-induced lesions in the nervous system. After about 4-6 wk of dosing, 2,5-HD induced distal axonopathy in normal quail and acute neurotoxicity in Quv quail.

Distal axonopathy does not occur without neurofilament accumulation in gamma-diketone neuropathy: comparative studies of normal and neurofilament-deficient quail.

The neurotoxic effects caused by chronic exposure to 2,5-hexanedione (2,5-HD) were investigated in normal and neurofilament (NF)-deficient quail (Quv strain). These quail were given 175 mg/kg per day of 2,5-HD intraperitoneally for 24 weeks. Five of nine normal quail showed clumsy gait. They had NF-rich axonal swellings in the distal parts of the peripheral nerves, ventral and lateral funiculus of the cervical cord, and cerebellar peduncles. Axonal degeneration consisting of accumulation of mitochondria, vesicles, microtubules and dense bodies was found distal to the axonal swellings. Testicular atrophy appeared in two normal quail. In contrast, four of nine Quv quail showed systemic tonic convulsion, and died of respiratory paralysis within 6 days. No significant changes in the nervous system or testis of these four dead Quv quail. The five other Quv quail survived and did not show any neurological signs. Again, no significant changes were detected in the nervous system or testis of the surviving Quv quail. The present study revealed that distal axonal degeneration did not occur without NF accumulation. These results suggest that NF accumulation is an essential factor in the development of distal axonopathy in gamma-diketone neuropathy.

Hepatic lesions in young rabbits experimentally infected with rabbit haemorrhagic disease virus.

Twenty young rabbits (eleven 2-week-old and nine 4-week-old) were experimentally infected with rabbit haemorrhagic disease virus (RHDV) to clarify susceptibility. They were killed chronologically up to 96 hours post-inoculation (PI) and examined for lesions. All inoculated rabbits were clinically normal, but grossly minute white or grey spots were detected throughout the liver. Histologically, the lesions consisted of aggregates of lymphocytes, macrophages and heterophils, with or without acidophilic bodies and necrotic hepatocytes. Immunohistochemically, RHDV antigens were found in the degenerated hepatocytes and in macrophages. The cellular aggregates were considered to be a reaction to necrotic hepatocytes infected with RHDV. It was concluded that some hepatocytes are susceptible to RHDV in young rabbits.

Analysis of transcriptional and translational activities of Marek's disease (MD) virus genes in MD central nervous system lesions in chickens.

The expression of Marek's disease virus (MDV) gene products and transcripts was observed in tissues obtained from the central nervous system (CNS) of chickens experimentally infected with a very virulent strain (Md/5) of MDV. Many cells antigen-positive for MDV early gene products, but not for late gene products, were detected immunohistochemically in the necrotizing lymphomatous lesions. The positive signals were found only in necrotic or degenerated neoplastic lymphoblasts. Abundant transcriptional activity of MDV genes was observed in the necrotizing lymphomatous lesions for immediate-early and early genes, but not for late ones, by the reverse-transcription polymerase chain reaction. In the non-necrotizing lymphomatous lesions, as well as non-suppurative ones, there were no or very few antigen-positive lymphoblasts for early and late genes, and little transcriptional activity of MDV genes. The necrotizing lesions of the lymphoma were associated with necrotizing vasculitis in which endothelial cells exhibited up-regulation of MHC class II antigen but no viral antigens. The present results indicate that only necrotizing lymphomatous lesions revealed abundant incomplete cytolytic cycle in MDV latently infected neoplastic lymphoblasts.

Cytology of feather pulp lesions from Marek's disease (MD) virus-infected chickens and its application for diagnosis and prediction of MD.

Cytological changes of feather pulp lesions (FPL) sampled chronologically from the same specific-pathogen free chickens inoculated with Marek's disease virus serotype 1 (MDV) were examined, comparing with their histological changes. The birds having Marek's disease (MD) lymphomas or nerve lesions exhibited the characteristic lesion changes on the cytological smears of FPL; the initial non-suppurative inflammatory to the late lymphomatous FPL. The birds having neither the MD visceral lymphomas nor the nerve lesions manifested only non-suppurative inflammatory FPL on the cytological smears throughout the experimental periods. Histological evaluation of FPL sampled from the same birds confirmed as above mentioned cytological results. From these results, the cytological evaluation of FPL proved to be an effective diagnostic and prognostic tool in foreseeing MD incidence.

Bronchiolar-alveolar carcinoma in a cow.

Bronchiolar-alveolar carcinoma was observed in the lung of an 8-year-old Holstein cow. Grossly, the lung contained multiple tumour masses, which were solid, yellowish-white in colour, and firm in consistency. These tumours also occurred in the liver, pancreas, uterus and lymph nodes in the thoracic, abdominal and pelvic cavities. Histologically, the masses were composed of abundant fibrous stroma and proliferating atypical cuboidal epithelial cells, occasionally forming glandular structures. Electron microscopy revealed that the neoplastic cells had microvilli and lamellar bodies in the cytoplasm, suggesting that they originated from immature respiratory epithelial cells differentiating towards either Clara cells or type II pneumocytes.

Gizzard adenocarcinoma in an aged Humboldt penguin (Spheniscus humboldti).

Spontaneous gizzard adenocarcinoma was found in a 15-year-old male Humboldt penguin (Spheniscus humboldti). The lesser curvature of the gizzard wall was extensively and markedly thickened with a hard white tumour mass. Histopathologically, the tumour in the gizzard consisted of two structures: small to large acini lined by cuboidal or flattened cells with poor stroma in the mucosa, and undifferentiated tumour cells arranged singly or in cords with acinar structures separated by dense fibrous tissue in the muscular layer. Small white metastatic tumours of the intestine and the pancreas had a similar histological appearance to that in the muscular layer of the gizzard. From the location of tumour in the gizzard and the stainability with combined alcian blue pH 2.5-periodic acid Schiff, it was considered that this tumour might originate from the lining cells of the tip of the gizzard mucosal folds.

Central nervous system lesions induced experimentally by a very virulent strain of Marek's disease virus in Marek's disease-resistant chickens.

The histological lesions of central nervous system (CNS) in Marek's disease-resistant chickens inoculated with a very virulent Marek's disease virus strain (vvMDV), Md/5, were examined. This vvMDV induced high incidences of CNS lesions as well as visceral and peripheral nerve lesions. The principal histopatho-logical changes of CNS consisted of non-suppurative meningoencephalomyelitis and lymphomatous lesion, which were categorized into two types, non-necrotizing and necrotizing. The main changes in the former type were perivascular cuffing of lymphoid cells of variable thickness. Although diffuse lymphomatous lesions were sometimes observed, gliosis, neuronal and axonal degeneration, and satellitosis as well as demyelination in the myelinated fibre paths, were infrequent. The most significant change of the latter type was necrotizing lymphomatous and, sometimes, non-suppurative inflammatory lesions (malacia). In the malacic foci, all the cells, including infiltrating lymphoid cells, neurons and glial cells, were necrotic or degenerated. The malacic lesions were frequently accompanied by fibrinoid necrosis of blood vessels. The present results indicate that necrotizing vasculitis associated with vvMDV may lead to ischaemic damage which in turn induces necrotizing lymphomatous and sometimes, meningoencephalomyelitis lesions. In addition, it is considered that vvMDV can induce a high incidence not only of CNS lesions, but also of visceral and nerve lesions in Marek's disease-resistant chickens.

Naturally-occurring adenovirus-associated gastrointestinal lesions in Coturnix (Coturnix coturnix) quail.

Farm-reared Coturnix quail less than 3 weeks old showed depression, ruffled feathers, diarrhoea and high mortality. Histological examination revealed basophilic intranuclear inclusion bodies mainly in the digestive tract, and rarely in the liver, kidney, nasal epithelium, conjunctiva and columnar epithelial cells within the mucosa of the bursa of Fabricius. The inclusions were more numerous in the caeca than in the small intestine. Ultrastructurally, they contained many adenovirus-like particles approximately 60 nm in diameter. This is the first evidence of adenoviral inclusions in the glandular epithelium of the gizzard, conjunctiva, plical epithelium of bursa of Fabricius, and mucosal epithelium of small and large intestines in Coturnix quail.

Hantavirus infection in SCID mice.

Severe combined immunodeficiency (SCID) mice were inoculated with Hantaan virus strain 76-118 (HTN) or Seoul virus strain SR-11 (SR) of hantaviruses. Susceptibility of SCID mice was compared with those of immunocompetent adult mice, newborn mice and nude mice. SCID mice inoculated with HTN or SR died 32 to 35 days after infection. Unlike newborn mice which also died of hantavirus infection, SCID mice survived longer than newborn mice and showed typical wasting symptoms rather than nervous symptoms. Immunohistochemical staining and virus isolation indicated that both HTN and SR inoculated SCID and SR inoculated nude mice showed systemic infection, but nude mice inoculated with SR survived for longer than 8 weeks after inoculation. Passive transfer of spleen cells from immunocompetent BALB/c mice conferred protection on SCID mice within 2 weeks of HTN infection. Immune mediated pathologic mechanism was examined by transferring the spleen cells to SCID mice inoculated with HTN virus 3 weeks before the cell transfer. The recipient SCID mice showed an increase of serum BUN level coinciding with the appearance of serum antibody to HTN virus, suggesting the immune mediated pathogenicity.

Cutaneous lesions in broiler chickens spontaneously affected with Marek's disease.

A total of 91 8- to 9-week-old broiler chickens with Marek's disease (MD) skin tumours ("skin leukosis"), collected from 15 farms at the processing plants, were examined pathologically. Grossly, the skin lesions comprised various sizes and numbers of feather follicular nodules, which tended to fuse with each other as their size increased. Histologically, the lesions were classified into five types: type A was small lymphoid cell aggregates (LCA) consisting mostly of small lymphocytes with a few lymphoblasts and very rare mitotic figures; type B had large LCA consisting mainly of small lymphocytes with considerable numbers of lymphoblasts and very rare mitotic figures; type C was characterized by large coalesced LCA consisting almost equally of small lymphocytes and lymphoblasts with infrequent mitotic figures; type D exhibited very large coalesced LCA consisting mainly of lymphoblasts with some small lymphocytes and occasional mitotic figures; type E had very large coalesced LCA consisting almost completely of lymphoblasts with frequent mitotic figures. The histological MD cutaneous lesions were related to the size of gross skin nodules, the small feather follicular nodules consisted mainly of types B and C with type A, whereas large fused feather follicular nodules were composed mainly of types D and E. Nuclear inclusions were frequently found in the feather follicular epithelium in all skin nodules except for the largest fused ones. MD visceral lesions were more pronounced in birds having marked skin leukotic lesions. Feather pulp lesions (FPL) were more related to the visceral than the skin lesions; the constituent cells of FPL were compatible with those of the former lesions.

Apocrine gland tumor of the eyelid in a dog.

A 13-year-old male Shetland Sheepdog with progressive exophthalmos had a neoplastic mass in the ocular adnexa. Histologically, this neoplasm was composed of duct-forming epithelial cells with decapitation secretion. Tumor cells invaded the globe through the tunica conjunctiva and replaced the vitreous body. The cornea, iris, ciliary body, and retina were extensively destroyed. Both the epithelial and spindle-shaped myoepithelial cells showed nuclear atypia and mitotic activity in the globe. The primary tumor was diagnosed as adenocarcinoma, probably originating from apocrine sweat glands of the eyelid, and the infiltrating intraocular neoplasm was diagnosed as a malignant mixed tumor.

Unusual lesions associated with avian poxvirus infection in rosy-faced lovebirds (Agapornis roseicollis).

An epornitic of avian pox occurred in rosy-faced lovebirds (Agapomis roseicollis). The infected birds showed a variety of lesions including cutaneous, diphtheritic, systemic and oncogenic entities. Proliferative changes with cytoplasmic inclusion bodies in the cornea, bursa of Fabricius, and cranial and nasal bones which were found in the present cases have not been described previously. Electron microscopic examination of the skin, cornea, and cranial and nasal bones revealed poxvirus virions in the inclusions. Secondary infection of candidiasis was very common in cutaneous pox lesions.

Esophageal/gastric adenocarcinoma in a dog.

A nine-year-old, intact female, mixed-breed dog was presented with a history of chronic regurgitation and weight loss. Endoscopy and contrast radiography confirmed the presence of a distal esophageal mass. The dog was euthanized, and histopathological diagnosis of the mass was an esophageal/gastric adenocarcinoma.