Nobuhiko Sunohara

Immunoelectron-microscopic demonstration of NACP/α-synuclein-epitopes on the filamentous component of Lewy bodies in Parkinson's disease and in dementia with Lewy bodies

We examined brains from Parkinsons disease and from dementia with Lewy bodies (LBs) by using antibodies to NACP/alpha-synuclein. Immunohistochemically, all of the antibodies against the amino-terminal region, NAC domain, and carboxyl-terminal region of NACP labeled not only LBs, pale bodies (PBs), and dystrophic neurites, but also fine thread-like structures in the neuronal perikarya (perikaryal threads) in the hypothalamus and brainstem nuclei. On electron microscopy, immunoreactive products were found to label the 9 to 12 nm-thick filamentous component (LB-filaments) of LBs, PBs, and perikaryal threads. The NACP-immunoreactive perikaryal threads, consisting of small bundles of LB-filaments and randomly oriented LB-filaments, presumably represent an initial stage of LB- or PB-formation. The present study indicates that the entire molecule of NACP is involved in the neuronal filament-aggregating processes of LB disorders.

Distal myopathy with rimmed vacuoles is allelic to hereditary inclusion body myopathy

Background: Distal myopathy with rimmed vacuoles (DMRV) is an autosomal-recessive disorder with preferential involvement of the tibialis anterior muscle that starts in young adulthood and spares quadriceps muscles. The disease locus has been mapped to chromosome 9p1-q1, the same region as the hereditary inclusion body myopathy (HIBM) locus. HIBM was originally described as rimmed vacuole myopathy sparing the quadriceps; therefore, the two diseases have been suspected to be allelic. Recently, HIBM was shown to be associated with the mutations in the gene encoding the bifunctional enzyme, UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE). Objective: To determine whether DMRV and HIBM are allelic. Methods: The GNE gene was sequenced in 34 patients with DMRV. The epimerase activity in lymphocytes from eight DMRV patients was also measured. Results: The authors identified 27 unrelated DMRV patients with homozygous or compound-heterozygous mutations in the GNE gene. DMRV patients had markedly decreased epimerase activity. Conclusions: DMRV is allelic to HIBM. Various mutations are associated with DMRV in Japan. The loss-of-function mutations in the GNE gene appear to cause DMRV/HIBM.

Cellular co-localization of phosphorylated tau- and NACP/α-synuclein-epitopes in Lewy bodies in sporadic Parkinson's disease and in dementia with Lewy bodies

The precursor of the non-Abeta-component of Alzheimers disease (AD) amyloid (NACP, alpha-synuclein) aggregates into insoluble filaments of Lewy bodies (LBs) in Parkinsons disease (PD) and dementia with LBs (DLB). The microtubule-associated protein tau is an integral component of filaments of neurofibrillary tangles (NFTs). NFTs are occasionally found in brains of PD and DLB; however, the presence of NFTs or tau-epitopes within LB-containing neurons is rare. Double-immunofluorescence study and peroxidase-immunohistochemical study in serial sections, performed to examine the co-localization of tau- and NACP-epitopes in the brainstem of PD and DLB, demonstrated that four different epitopes of tau including phosphorylation-dependent and independent ones were present in a minority of LBs, but more often than previously considered. A tau (tau2)-epitope was localized to filaments in the outer layers of brainstem-type LBs by immunoelectron microscopy. Therefore, we conclude that tau is incorporated into filaments in certain LBs. Extensive investigation has enabled us to classify this co-localization into four types: type 1, LBs with ring-shaped tau-immunoreactivity; type 2, LBs surrounded by NFTs; type 3, NACP- and tau-immunoreactive filamentous and granular masses; and type 4, NACP- and tau-immunoreactive dystrophic neurites. This study raises a new question whether aggregation and hyperphosphorylation of tau in PD and DLB are triggered by the collapse of intraneuronal organization of microtubules due to NACP-filament aggregation in neuronal perikarya and axons.

Ultrastructural characterization of the tau-immunoreactive tubules in the oligodendroglial perikarya and their inner loop processes in progressive supranuclear palsy

Abstract Coiled bodies and interfascicular threads are conspicuous white matter abnormalities of brains of patients with progressive supranuclear palsy (PSP). Both structures are argyrophilic and immunoreactive for the microtubule-binding protein tau. This report concerns the ultrastructural localization of interfascicular threads and their relationship to coiled bodies in five PSP patients. We showed for the first time that abnormal tubules with a 13- to 15-nm diameter and fuzzy outer contours were the common structures of coiled bodies in the oligodendroglial perikarya and of interfascicular threads. Moreover, the tubules were immunolabeled by anti-tau antibodies. The abnormal tau-positive tubules of interfascicular threads were located in the inner loop of the myelin sheath. Our study further indicated that the thread-like structures in the white matter comprised, at least in part, oligodendroglial processes, and that they were also present in gray matter. We consider that the formation of coiled bodies in the perikarya and of interfascicular threads represents a common cytoskeletal abnormality of the oligodendroglia of PSP patients. Moreover, even though the white matter alterations of PSP resemble those of corticobasal degeneration, there are certain ultrastructural differences in the abnormal oligodendroglial tubules of the two diseases.

Medial nigral dopamine neurons have rich neurotrophin support in humans.

: To assess the action of neurotrophin in human dopaminergic neurons, we studied the immunolocalization of neurotrophins or trks in human substantia nigra pars compacta (SNc). The neuromelanin-containing neurons in the SNc showed immunoreactivities for neurotrophins or trks, suggesting an autocrine/paracrine regulation. Quantitative analysis revealed that the percentage of those expressing NGF-like immunoreactivity (NGF-LI), BDNF-LI, NT3-LI, trkA-LI, trkB-LI, or trkC-LI was 66%, 74%, 85%, 66%, 71% or 86%, respectively. The percentage of cells expressing neurotrophins or trks was higher in the medial part than in the lateral part of the SNc. The preferential expression of neurotrophin-trk systems in the medial neurons may, at least partially, explain the differential susceptibility in Parkinsons disease.

Small increase in triplet repeat length of cerebellum from patients with myotonic dystrophy

Myotonic dystrophy (DM) is genetically characterized by abnormal expansion of an unstable CTG trinucleotide repeat, located in the 3′-untranslated region of mRNA encoding the family of serine-threonine protein kinases. DNA extracted from various organs of patients with DM was analyzed by the Southern blotting method. We identified differently expanded bands in DNAs from various tissues from patients with DM. In studying the length of the CTG repeat in different regions of the brain, we found a noticeably small increase in repeat length in the cerebellum compared with other tissues. While this phenomenon has been reported in other triplet repeat diseases such as Huntington disease, spinocerebellar ataxia type 1, and dentatorubral-pallidoluysian atrophy, we are the first to describe it in DM. Although the mechanism of expansion of the triplet repeat remains to be defined, the tissue-dependent somatic mosaicism suggests that its occurrence may depend on the differentiated state of each tissue.

Action‐induced rhythmic dystonia An autopsy case

We studied a patient with action-induced rhythmic dystonia that followed a stroke. Postmortem studies showed an infarct in the right posterolateral ventral part of the thalamus. Electrophysiologic analysis indicated that the eliciting factor of the involuntary movement was an impulse, promoting voluntary contraction of muscle. CSF 5-HIAA content was low, and HVA was high. Administration of 5-HTP and clonazepam abolished the involuntary movements.

Neutrophin switching in spinal motoneurons of amyotrophic lateral sclerosis.

TO clarify the roles of neurotrophins in the human spinal motoneurons, with special reference to amyotrophic lateral sclerosis (ALS), we studied the immunohistochemical localizations of neurotrophins and their receptors in spinal cords of patients with ALS and compared them with controls. In the controls, the majority of motoneurons showed BDNF-, NT3-, trkB-and trkC-like immunoreactivity (-LI) suggesting that the motoneurons receive an autocrine regulation by both BDNF and NT3. In ALS patients, about three-quarters of the motoneurons had degenerated and the remaining motoneurons showed significantly decreased BDNF-LI, increased NGF-and trkA-LI. These findings indicated neurotrophin-switching in the remaining spinal motoneurons of ALS patients from BDNF and NT3 responsive to NGF responsive.

Glabella tap sign: Is it due to a lack of R2-habituation?

In 30 patients with Parkinsons disease, 55 patients with other neurological disorders and 25 normal subjects, both upper eyelid movements and orbicularis oculi reflexes to repetitive glabella taps were simultaneously recorded using a newly devised apparatus for the measurement of eyelid movement. Upper lid movement during the blink reflex has been thought to correspond to the late component of the two components of the orbicularis oculi reflex, and failure of habituation of the late component to repetitive stimuli has been considered to be responsible for the glabella tap sign. However, the present study showed that the eyelid lowered after the early component (R1), and habituation of the late component (R2) was recognized in 31% of subjects with the glabella tap sign. This shows that there is no direct causal relationship between the glabella tap sign and lack of the habituation of the late component.

Immunohistochemical and ultrastructural characterization of ubiquitinated eosinophilic fibrillary neuronal inclusions in sporadic amyotrophic lateral sclerosis

Abstract We found eosinophilic fibrillary neuronal inclusions (EFNI) that were argyrophilic and immunoreactive for anti-ubiquitin in the cerebral cortex of a patient with sporadic amyotrophic lateral sclerosis (ALS) and mild personality changes. Both hematoxylin and eosin and Bodian’s preparations revealed the EFNI to be rod-, flame-shaped, or spherical structures existing within the swollen neuronal perinuclear region in the third, fifth, and sixth layers of the fronto-parieto-temporal cortices including the primary motor cortex. On electron microscopy, filamentous profiles aggregated and formed a single bundle or globule in the neuronal perikaryon without any limiting membrane. Most EFNI had a characteristic multiple layer arrangement. The inner core consisted of randomly oriented granule-free tubules with a fuzzy outer contour, measuring 15–20 nm in diameter. The surrounding layer was made up of granule-associated filaments, electron-dense free granules, and small vesicular profiles. Large autolysosome-like membrane-bound vesicular profiles were found scattered at the periphery. Neurofilaments were usually mingled with in the surrounding cytoplasm. Many EFNI were also found in dendrites, but only a few in axons. Both granule-free tubules and granule-associated filaments expressed ubiquitin protein epitopes. Aberrant phosphorylation of neurofilament protein and induction of αB-crystallin were shown to exist in EFNI-bearing swollen neurons. Despite having a variety of histological appearances, our observations revealed that EFNI all have common immunocytochemical and ultrastructural characteristics, and thus we assume that EFNI represent a series of cytological alterations in the motor and extra-motor cortices of ALS patients.