Kaoru Okuizumi

Analysis of the expression level of α-synuclein mRNA using postmortem brain samples from pathologically confirmed cases of multiple system atrophy

Abstract. To determine whether multiple system atrophy (MSA) is associated with altered expression levels of the α-synuclein messenger RNA (mRNA), we performed quantitative reverse transcription polymerase chain reaction for α-synuclein mRNA using postmortem brain samples from 11 cases of MSA and 14 age-matched control subjects. The brain specimens used in this study contained both the gray matter and white matter, which were dissected from the frontal, temporal or occipital lobe. The expression levels of α-synuclein mRNA in the brain specimens of MSA cases were not different from those of the control subjects. These results suggest that the transcriptional regulation of the α-synuclein gene is unlikely to be affected in MSA brains.

No mutation in the entire coding region of the α-synuclein gene in pathologically confirmed cases of multiple system atrophy

To determine whether mutations in the coding region of the alpha-synuclein gene are relevant in cases of multiple system atrophy (MSA), detailed nucleotide sequence analysis of the alpha-synuclein gene was performed using total RNA obtained from autopsied brain specimens of 11 pathologically confirmed cases of MSA. The brain specimens used in this study contained both gray and white matter, which were dissected from the frontal, temporal or occipital lobe. No nucleotide alterations were found in the entire coding region of the alpha-synuclein gene in any of the cases. While mutations in the regulatory or intronic regions of the gene were not ruled out, our results suggest that mutations in the coding region of the alpha-synuclein gene are unlikely to contribute to the pathogenesis of MSA.

Apolipoprotein E ε4 allele and progression of cortical Lewy body pathology in Parkinson’s disease

Abstract To elucidate whether the apolipoprotein E ɛ4 allele (APOE4) affects cortical neuropathology in Parkinson’s disease (PD), we determined APOE genotypes and quantified the densities of cortical Lewy bodies (LBs), amyloid plaques and neurofibrillary tangles in 22 autopsy-proven PD cases (12 with dementia; 10 without dementia) that were not accompanied by Alzheimer’s disease. The APOE4 frequency in the demented patient group was 0.21, which was significantly higher than that in Japanese controls (P < 0.04). LB densities in demented PD patients were significantly higher than those in non-demented PD patients, despite the shorter disease duration in the former. Moreover, plaque density in the temporal cortex and LB density in the cingulate cortex were significantly higher in the group with APOE4 than in that without the allele. There was no difference in tangle density between these two groups. These results suggest that APOE4 may influence the increase in the number of cortical LBs and amyloid plaques in PD. It is possible that when PD occurs in individuals with APOE4, concomitantly evolving cortical LB pathology in a proportion of cases results in limbic (transitional) or neocortical-type LB disease.

Autosomal dominant diffuse Lewy body disease

Abstract We describe a Japanese family with parkinsonism and later-onset dementia. The proband developed parkinsonism at the age of 61 years, followed by dementia starting when she was 67. Her uncle, who was also her husband, died at the age of 78 years after 7- and 5-year histories of parkinsonism and dementia, respectively. Pathological examination of these two patients showed marked neuronal loss with Lewy bodies (LBs) in the brain stem pigmented nuclei and numerous cortical LBs and ubiquitin-positive hippocampal CA2/3 neurites were observed. The proband also had many amyloid plaques. Their two sons developed similar parkinsonism at the ages of 39 and 28 years and also suffered later-onset dementia. The apolipoprotein E genotype of the proband, her uncle and one of their sons was ɛ3/4 and that of the other son was ɛ4/4. These findings strongly suggest that this family has autosomal dominant diffuse LB disease.

mtDNA Polymorphisms in Japanese Sporadic Alzheimer’s Disease

We screened 92 Japanese patients with sporadic AD (clinically diagnosed: 72 cases; autopsy-confirmed: 20 cases) and 59 age-matched controls for mitochondrial polymorphisms previously reported to be associated with increased risk in Caucasian AD. The polymorphisms in tRNA(Gln) (nt. 4336), 16S rRNA (nt. 3196), and ND1 (nt. 3397) were not found in either in Japanese AD or age-matched controls. The frequencies of these polymorphisms in Japanese seems to be very rare if not absent, indicating that these three mutations are not likely to be genetic risk factors of Japanese AD. In the analysis of polymorphisms of 12S rRNA, however, we identified two novel mutations, an insertion of three cytosines and an A to G transition at nt. 856, which have not been described before. The insertion of three cytosines was observed in one of the 90 AD cases, but not in 59 normal controls. The A to G transition at nt. 856 was found in 2 of the 90 AD cases, but not in 59 normal controls. These results raise the possibility that the mutations in the 12S rRNA are genetic risk factors for AD in Japanese population.

Pick's disease: selective occurrence of apolipoprotein E-immunoreactive Pick bodies in the limbic system

Abstract We carried out immunohistochemical examination of apolipoprotein E (apoE) in brains from two patients with Pick’s disease. In these cases 1 and 2, the APOE genotypes were ɛ3/4 and ɛ3/3, respectively. In both cases, numerous argyrophilic globular intraneuronal inclusions, Pick bodies (PBs), were distributed widely throughout the brain, and immunohistochemically were occasionally positive for apoE. Interestingly, such apoE-immunoreactive PBs were virtually restricted to neurons in the limbic system; in the dentate gyrus, the proportion of apoE-immunoreactive PBs relative to the total number of argyrophilic PBs was 5.0% in case 1 and 2.7% in case 2, whereas in the frontal and temporal neocortices it was less than 0.1% in both cases. Diffuse cytoplasmic immunoreactivity for apoE was found in only a few limbic system neurons without PBs in both cases. In conclusion, it is considered that apoE may not be positively involved in the process of PB formation and that the preferential distribution of apoE-immunoreactive PBs in the limbic system may reflect the presence of certain regional factors associated with the synthesis or metabolism of apoE in this particular system.

Alzheimer's disease as a polygenic disease

Recent advances in molecular genetics have enabled the identification of the causative genes for early‐onset familial Alzheimers disease (AD). However, sporadic and late‐onset familial AD, the most common forms of AD, are considered to be polygenic disorders. The presence of APOE4, one of the specific alleles of the apolipoprotein E gene, has been established as a major genetic risk factor for the development of AD. Additional risk factors are under active investigation. Such new approaches are expected to establish preventive measures or treatments for AD.