Naoaki Goto

Apoptosis in the aged dog brain.

Abstract Apoptosis similar to that seen in Alzheimer’s disease patients was found in the brain of aged dogs by the TUNEL method of detecting in situ DNA fragmentation. Apoptosis was observed in both neurons and glial cells, and was morphologically characterized by round and swollen cytoplasm and aggregated nuclear chromatin, although these changes were slight. Neurons and astrocytes in the gray matter and oligodendrocytes in the white matter were affected. The number of ApopTag-positive brain cells increased slightly with age, but was not correlated to the number of senile plaques. A good correlation between the number of ApopTag-positive cells and the dementia index was clearly found. The present study indicates that brain cell apoptosis could account for dementia in aged dogs and suggested that aged dogs may be useful as a simplified animal model for Alzheimer’s disease in man.

Histopathological studies of senile plaques and cerebral amyloidosis in cynomolgus monkeys

Senile plaques (SPs) and cerebral amyloid angiopathy (CAA), pathological hallmarks of Alzheimers disease, have not been thoroughly investigated histopathologically in nonhuman primates. To determine the onset age and histopathological characteristics of SPs and CAA, we examined the brains of 64 cynomolgus monkeys (Macaca fascicularis) from 2 to 35 years old. Mature (classical and primitive) plaques appeared in 16 out of 25 monkeys that were >20 years old. Moreover, mature plaques were observed more frequently than diffuse plaques and were located in the temporal cortex of the superior or inferior gyri and amygdala. Diffuse plaques in contrast to mature plaques did not show definite tendencies in onset age and distribution. CAA appeared in more than 22‐year‐old monkeys in 10 out of 16 animals and was frequently observed in capillaries and often found adjoining mature plaques. During immunohistochemical examination, an antiserum for amyloid β protein (Aβ) 1–40 could detect all SPs, whereas a monoclonal antibody for Aβ 8–17 could not detect any diffuse plaques and only one third of the primitive plaques. As for CAA, the polyclonal antiserum was more sensitive than the monoclonal antibody. The present study describes the histopathological features of SPs and CAA in old cynomolgus monkeys.

Production of mice from a lethal coronavirus infection in the central nervous system by adoptive transfer of virus-specific T cell clones

Abstract The protective effect of a mouse hepatitis virus type-4 (MHV-4)-specific CD8+ cytotoxic T cell clone and a CD4+ helper T cell clone was examined by the adoptive transfer into brains of mice lethally infected with MHV-4. Mice survived acute encephalitis if more than 5 × 105 cells of either type of the virus-specific T cell clones had been transfered into H-2-matched recipients by 1 day post-infection. Although the adoptive transfer of both types of the T cell clones suppressed viral growth and viral antigen-positive cells in the brains, a significant inhibition of virus replication by the cytotoxic T cell clone was detected prior to that induced by the helper T cell clone. Histologically, cell destruction was prominent in the brains of mice which received the cytotoxic T cell clone. These results demonstrate that both the CD8+ cytotoxic T cell and the CD4+ helper T cell can protect mice from a lethal MHV-4 infection in the central nervous system.

A Retrospective Study of Canine Senile Plaques and Cerebral Amyloid Angiopathy

Epidemiologic and morphologic features of canine senile plaques (SPs) and cerebral amyloid angiopathy (CAA) were examined in 69 necropsied dogs. Dogs having only SPs (diffuse plaques) frequently suffered from malignant neoplasms, and their mean age was significantly lower than that of dogs with CAA only. Morphologically, diffuse plaques showed wide distribution compared with amyloid plaques or CAA and were predominantly concentrated in the frontal cortex. We were unable to find any significant relationship between the severity of the SPs and individual age. These findings may indicate that the occurrence of canine SPs is not strictly associated with aging only and that additional factors are related to the occurrence of SPs, especially diffuse plaques.

Senile plaques in very aged cats.

Abstract Senile plaques were found in the cerebral cortices of three very aged cats (more than 18 years old). The plaques consisted of a coarse assembly of silver staining-positive materials, and was morphologically different from the well-known classical, primitive, and diffuse plaques. Congophilic amyloid angiopathy was observed in a few cortical arterioles of the oldest cat (20 years old). The senile plaques and a few cortical blood vessels were immunopositive for amyloid β-protein (Aβ). Aβ-positive materials were also sparsely distributed in the cortical neuropil but did not form senile plaques there. These findings should help to clarify the development of senile plaques and the early stage of Aβ deposition.

Isolation of the avian transforming retrovirus, AS42, carrying the v-maf oncogene and initial characterization of its gene product.

A novel avian transforming retrovirus was isolated from a chicken musculoaponeurotic fibrosarcoma. This virus (called AS42) induces tumors histopathologically indistinguishable from the original sarcoma after a long latent period when inoculated into newborn chickens. AS42 also exhibits a weak transforming activity when infected into chicken embryo fibroblasts (CEF). This virus is replication-defective and associated with a helper virus of subgroup A (called ASAV). An AS42-specific protein of about 100 kDa was immunoprecipitated from lysates of AS42-transformed CEF with antiserum directed against avian retrovirus virion proteins. Molecular analysis of the genomic structure of the AS42 virus has revealed that this 100-kDa protein represents a novel oncogene, v-maf of cellular origin, which is fused with a part of the viral gag gene (Nishizawa et al., Proc. Natl. Acad. Sci. USA 86, 7711-7715, 1989). Interestingly, some size variation was observed among the gag-maf fusion proteins found in individual clones of transformed CEF. Consistent with this observation, Southern blot analyses and nucleotide sequence determination of several independent isolates of proviral DNA indicated that this virus segregates multiple forms of deletion mutants, probably through homologous recombinations among the repetitive sequences present within the v-maf coding region.

Carboxyl end-specific monoclonal antibodies to amyloid β protein (Aβ) subtypes (Aβ40 and Aβ42(43)) differentiate Aβ in senile plaques and amyloid angiopathy in brains of aged cynomolgus monkeys

Abstract Senile plaques (SPs) and cerebral amyloid angiopathy (CAA) in the brains of five aged (20–26 years old) cynomolgus monkeys were investigated immunohistochemically using two monoclonal antibodies (anti-Aβ 40 (BA27) and anti-Aβ 42(43) (BC05)) that can differentiate the carboxyl termini of amyloid β protein (Aβ) subtypes. In four of five animals, all types of SPs (i.e. diffuse, primitive, and classical plaques; DPs, PPs, and CPs, respectively) were identified by BC05. However, BA27 did not label DPs and stained only about one third of PPs and CPs, mainly labeling granular structures and cored portions, respectively. In CAA, lesions of cortical capillaries reacted to BC05 in four of five cases, but rarely and weakly to BA27 in two of five cases. On the other hand, lesions of parenchymal and meningeal arterioles were stained by both BA27 and BC05. These staining profiles of SPs in cynomolgus monkeys correspond well to those in humans, although there are two remarkable features in cynomolgus monkeys. First, BA27 stained PPs associated with granular structures. Secondly, capillary Aβ reacted intensely to BC05 but only slightly to BA27. Despite these unique features, the results suggest that aged cynomolgus monkeys can be used to investigate the pathogenesis of Aβ deposition in SPs and CAA.

Senile Plaques and Other Senile Changes in the Brain of an Aged American Black Bear

A female American black bear (Euarctos ursus americanus) over 20 years old had shown epileptiform neurologic signs starting in March 1992 and was found dead unexpectedly 8 months later. At necropsy, pulmonary and intrabronchial hemorrhage was noted. In the brain, the leptomeninges exhibited slight thickening, and petechiae were evident in the hippocampus. Histopathologic examination of the brain revealed several senile changes: numerous senile plaques, amyloid deposition in cerebromeningeal arterioles, mineral deposition in the pallidum, and numerous corpora amylacea in the cerebellum.

Necrotizing meningoencephalitis in pug dogs in Japan

This report records necrotizing meningoencephalitis in three pug dogs. It is the first record of the disease in Japan. There were three characteristic histopathological findings, namely (1) a non-suppurative inflammatory cell infiltration of the cerebral hemispheres, including both gray and white matter, (2) meningeal and perivascular infiltrates of mononuclear cells, with a strong tendency to invade the underlying or surrounding brain parenchyma, and (3) selective cerebral cortical necrosis, often occurring without a concurrent inflammatory reaction. The three cases, which were diagnosed as pug dog encephalitis, resembled those previously reported in the United States of America, Switzerland and Italy. All affected animals were females with clinical histories of pregnancy or phantom pregnancy 2 weeks or less before the onset of the clinical signs.

Persistent Infection with Mouse Hepatitis Virus, JHM Strain in DBT Cell Culture

After inoculation with JHM strain into DBT cell monolayers, a persistently infected DBT cell culture was established without producing typical cytopathic changes after about 15th passages. By immunofluorescence virus specific antigen was demonstrated in 10 to 15% DBT cells. This persistently infected culture (JHM-CC) was resistant to superinfection with parental JHM, but such resistance was not shown against vesicular stomatitis virus. JHM-CC virus produced small plaques on DBT cell monolayers. Temperature sensitive (TS) mutant, defective interfering (DI) particle or interferon was not detected in the JHM-CC. To intracerebral inoculation with JHM-CC virus, cortisone treated ICR mice survived without showing clinical signs, however, demyelinating lesions were produced in the brain and spinal cord of them.