Parkinson's disease is a type of amyloidosis featuring accumulation of amyloid fibrils of α-synuclein.

Many neurodegenerative diseases are characterized by the accumulation of abnormal protein aggregates in the brain. In Parkinson's disease (PD), α-synuclein (α-syn) forms such aggregates called Lewy bodies (LBs). Recently, it has been reported that aggregates of α-syn with a cross-ß structure are capable of propagating within the brain in a prionlike manner. However, the presence of cross-ß sheet-rich aggregates in LBs has not been experimentally demonstrated so far. Here, we examined LBs in thin sections of autopsy brains of patients with PD using microbeam X-ray diffraction (XRD) and found that some of them gave a diffraction pattern typical of a cross-ß structure. This result confirms that LBs in the brain of PD patients contain amyloid fibrils with a cross-ß structure and supports the validity of in vitro propagation experiments using artificially formed amyloid fibrils of α-syn. Notably, our finding supports the concept that PD is a type of amyloidosis, a disease featuring the accumulation of amyloid fibrils of α-syn.

[A case of adult-onset Sturge-Weber syndrome type III without intracranial calcification, presenting with transient homonymous hemianopia].

Sturge-Weber syndrome (SWS) is a rare neurocutaneous disorder. Almost all cases of SWS are diagnosed in children, but some are diagnosed in adults. We describe a case of isolated leptomeningeal angiomatosis without intracranial calcification. A 33-year-old woman was admitted because of sudden-onset right homonymous hemianopia with headache and nausea. These symptoms disappeared by the next morning. She had no history of seizure or mental retardation. No facial angioma was found on physical examination. Brain CT showed no intracranial calcification or atrophic cortex. The blood and cerebrospinal fluid analyses yielded normal results. The findings in the electroencephalogram were unremarkable. MRI with susceptibility weighting (SWI) revealed dilated transmedullary veins in the left occipital lobe. Contrast-enhanced T1-weighted imaging (CE-T1WI) illustrated abnormal leptomeningeal enhancement in the left occipitoparietal cortex and enhancement and enlargement of the choroid plexus in the left lateral ventricle. Post-gadolinium contrast-enhanced f FLAIR imaging demonstrated more extensive enhancement of the leptomeningeal lesions than did CE-T1WI. The symptoms and the findings on these images were suggestive of a diagnosis of SWS type III. Clinicians should keep in mind that some cases of SWS manifest with only minor symptoms, such as migraine. If SWS is suspected, SWI and contrast-enhanced MRI should be performed.

[A case of systemic AL amyloidosis diagnosed on muscle biopsy].

A 69-year-old man was admitted to our hospital with a 1-year history of progressive easy fatigability while walking. He presented with proximal muscle weakness dominant in the lower extremities, hoarseness, and mild dysphagia. Muscle pseudo-hypertrophy was observed in the gastrocnemius. A biopsy specimen from the left deltoid muscle revealed amyloid deposition in the blood vessels and ring-like fibers. These findings suggested amyloid myopathy. The serum and urine immunofixation electrophoresis detected κ type Bence-Jones proteins, and bone marrow examination showed an increase in atypical plasma cells; thus, we established a diagnosis of multiple myeloma. Thereafter, he experienced frequent diarrhea, and the gastrointestinal endoscopy revealed extensive amyloid deposition in the upper and lower digestive tract. We started treatment with lenalidomide and dexamethasone; however, his condition worsened, and he died of aspiration pneumonia. Amyloid myopathy indicated systemic AL amyloidosis; therefore, muscle biopsy was necessary in this case.

[An autopsy case of elderly-onset herpes simplex encephalitis with acute respiratory failure caused by brainstem lesions].

An 89-year-old man was admitted because of persistent fever and impaired consciousness. On admission, his consciousness level was E3V3M4 according to the Glasgow Coma Scale. MRI of the brain showed high intensity lesions in the bilateral cingulate gyri. In the cerebrospinal fluid, both cell counts and glucose level were in the normal ranges. He had received antibiotics and intravenous isotonic saline. On the fifth day of hospitalization, blood examination revealed elevation of anti-herpes simplex virus (HSV) immunoglobulin M antibody, and herpes simplex encephalitis (HSE) was diagnosed. Despite treatment with acyclovir, his respiratory function and consciousness level deteriorated rapidly. On the eighth day, he died of respiratory failure. At autopsy, the brain showed multiple softenings of the gray and white matter in the hippocampus, amygdala, and temporal, insular, and cingulate cortices. Some of these lesions were hemorrhagic. Microscopic examination revealed that the lesions were necrotic and associated with perivascular inflammatory cell infiltration in the limbic system, hypothalamus, brainstem tegmentum area, and medulla. Eosinophilic intranuclear inclusions were rarely found in the astrocytes in the medulla. Immunohistochemistry revealed anti-HSV-1 antibody positive neurons in the brainstem tegmentum including reticular formation and the raphe nuclei. HSV-DNA was also detected in the postmortem cerebrospinal fluid. This was a rare case of HSE in which inflammation in the brainstem proved to be the cause of lethal respiratory failure.

The secondary structural difference between Lewy body and glial cytoplasmic inclusion in autopsy brain with synchrotron FTIR micro-spectroscopy.

Lewy bodies (LBs) and glial cytoplasmic inclusions (GCIs) are specific aggregates found in Parkinson's disease (PD) and multiple system atrophy (MSA), respectively. These aggregates mainly consist of α-synuclein (α-syn) and have been reported to propagate in the brain. In animal experiments, the fibrils of α-syn propagate similarly to prions but there is still insufficient evidence to establish this finding in humans. Here, we analysed the protein structure of these aggregates in the autopsy brains of patients by synchrotron Fourier-transform infrared micro-spectroscopy (FTIRM) analysis without extracting or artificially amplifying the aggregates. As a result, we found that the content of the ß-sheet structure in LBs in patients with PD was significantly higher than that in GCIs in patients with MSA (52.6 ± 1.9% in PD vs. 38.1 ± 0.9% in MSA, P < 0.001). These structural differences may provide clues to the differences in phenotypes of PD and MSA.

Ultrasonication-based rapid amplification of α-synuclein aggregates in cerebrospinal fluid.

α-Synuclein aggregates, a key hallmark of the pathogenesis of Parkinson's disease, can be amplified by using their seeding activity, and the evaluation of the seeding activity of cerebrospinal fluid (CSF) is reportedly useful for diagnosis. However, conventional shaking-based assays are time-consuming procedures, and the clinical significance of the diversity of seeding activity among patients remains to be clarified. Previously, we reported a high-throughput ultrasonication-induced amyloid fibrillation assay. Here, we adapted this assay to amplify and detect α-synuclein aggregates from CSF, and investigated the correlation between seeding activity and clinical indicators. We confirmed that this assay could detect α-synuclein aggregates prepared in vitro and also aggregates released from cultured cells. The seeding activity of CSF correlated with the levels of α-synuclein oligomers measured by an enzyme-linked immunosorbent assay. Moreover, the seeding activity of CSF from patients with Parkinson's disease was higher than that of control patients. Notably, the lag time of patients with Parkinson's disease was significantly correlated with the MIBG heart-to-mediastinum ratio. These findings showed that our ultrasonication-based assay can rapidly amplify misfolded α-synuclein and can evaluate the seeding activity of CSF.

The localization of α-synuclein in the process of differentiation of human erythroid cells.

Although the neuronal protein α-synuclein (α-syn) is thought to play a central role in the pathogenesis of Parkinson's disease (PD), its physiological function remains unknown. It is known that α-syn is also abundantly expressed in erythrocytes. However, its role in erythrocytes is also unknown. In the present study, we investigated the localization of α-syn in human erythroblasts and erythrocytes. Protein expression of α-syn increased during terminal differentiation of erythroblasts (from day 7 to day 13), whereas its mRNA level peaked at day 11. α-syn was detected in the nucleus, and was also seen in the cytoplasm and at the plasma membrane after day 11. In erythroblasts undergoing nucleus extrusion (day 13), α-syn was detected at the periphery of the nucleus. Interestingly, we found that recombinant α-syn binds to trypsinized inside-out vesicles of erythrocytes and phosphatidylserine (PS) liposomes. The dissociation constants for binding to PS/phosphatidylcholine (PC) liposomes of N-terminally acetylated (NAc) α-syn was lower than that of non NAc α-syn. This suggests that N-terminal acetylation plays a significant functional role. The results of the present study collectively suggest that α-syn is involved in the enucleation of erythroblasts and the stabilization of erythroid membranes.

Dynamical Behavior of Human α-Synuclein Studied by Quasielastic Neutron Scattering.

α-synuclein (αSyn) is a protein consisting of 140 amino acid residues and is abundant in the presynaptic nerve terminals in the brain. Although its precise function is unknown, the filamentous aggregates (amyloid fibrils) of αSyn have been shown to be involved in the pathogenesis of Parkinson's disease, which is a progressive neurodegenerative disorder. To understand the pathogenesis mechanism of this disease, the mechanism of the amyloid fibril formation of αSyn must be elucidated. Purified αSyn from bacterial expression is monomeric but intrinsically disordered in solution and forms amyloid fibrils under various conditions. As a first step toward elucidating the mechanism of the fibril formation of αSyn, we investigated dynamical behavior of the purified αSyn in the monomeric state and the fibril state using quasielastic neutron scattering (QENS). We prepared the solution sample of 9.5 mg/ml purified αSyn, and that of 46 mg/ml αSyn in the fibril state, both at pD 7.4 in D2O. The QENS experiments on these samples were performed using the near-backscattering spectrometer, BL02 (DNA), at the Materials and Life Science Facility at the Japan Accelerator Research Complex, Japan. Analysis of the QENS spectra obtained shows that diffusive global motions are observed in the monomeric state but largely suppressed in the fibril state. However, the amplitude of the side chain motion is shown to be larger in the fibril state than in the monomeric state. This implies that significant solvent space exists within the fibrils, which is attributed to the αSyn molecules within the fibrils having a distribution of conformations. The larger amplitude of the side chain motion in the fibril state than in the monomeric state implies that the fibril state is entropically favorable.

A small-angle X-ray scattering study of alpha-synuclein from human red blood cells.

α-synuclein (α-syn) is the main component of Lewy bodies, which are neuropathological hallmarks of patients with Parkinson's disease. As it has been controversial whether human α-syn from erythrocytes exists as a tetramer under physiological conditions, we tried solving this issue by the small-angle X-ray solution scattering method. Under two different conditions (high ionic strength with a Tris buffer and low ionic strength with an ammonium acetate buffer), no evidence was found for the presence of tetramer. When comparing erythrocyte and recombinant α-syn molecules, we found no significant difference of the molecular weight and the secondary structure although the buffer conditions strongly affect the radius of gyration of the protein. The results indicate that, even though a stable tetramer may not be formed, conformation of α-syn depends much on its environment, which may be the reason for its tendency to aggregate in cells.

[A case of new-onset refractory status epilepticus (NORSE) with an autoimmune etiology].

A 23-year-old man presented tonic-clonic seizure a week after an episode of antecedent infection. Although several anticonvulsants were used, convulsive attacks were not resolved and intravenous anesthetics were used to stop status epileptics. After combination of immunotherapies (high-dose intravenous methylprednisolone, immune absorbance and intravenous immunoglobulin (IVIg) therapies), frequency of convulsive attacks decreased, however, disturbance of consciousness was not recovered. All anti-neuronal antibodies tested were negative. Indirect immunofluorescence using the serum and rat brain section revealed positive signals in cytoplasm and nucleus in hippocampal neurons, strongly suggesting that this case has an autoimmune pathogenesis. The clinical features and course of this patient are well consistent with those in new-onset refractory status epilepticus (NORSE). The result of immunohistochemical analysis supports the hypothesis that NORSE has an autoimmune pathomechanism.

Synchrotron FTIR micro-spectroscopy for structural analysis of Lewy bodies in the brain of Parkinson's disease patients.

Lewy bodies (LBs), which mainly consist of α-synuclein (α-syn), are neuropathological hallmarks of patients with Parkinson's disease (PD). The fine structure of LBs is unknown, and LBs cannot be made artificially. Nevertheless, many studies have described fibrillisation using recombinant α-syn purified from E. coli. An extremely fundamental problem is whether the structure of LBs is the same as that of recombinant amyloid fibrils. Thus, we used synchrotron Fourier transform infrared micro-spectroscopy (FTIRM) to analyse the fine structure of LBs in the brain of PD patients. Our results showed a shift in the infrared spectrum that indicates abundance of a ß-sheet-rich structure in LBs. Also, 2D infrared mapping of LBs revealed that the content of the ß-sheet structure is higher in the halo than in the core, and the core contains a large amount of proteins and lipids.

[A case of progressive ataxia and palatal tremor (PAPT) with ear clicks].

A 71-year-old man noted clicking sounds in the ear. At the age of 75, he developed progressive unsteadiness of gait and became unable to walk without assistance at the age of 76. There was no family history of neurologic illness. Neurological examination revealed truncal ataxia and 1-2 Hz rhythmic palatal tremor, which persisted during sleep. Consistently, brain magnetic resonance imaging showed mild cerebellar atrophy and increased signal intensity of bilateral inferior olivary nuclei on T2-weighted image. progressive ataxia and palatal tremor (PAPT) has recently been described as a rare sporadic neurodegenerative disease and the features of our case consistent with those of PAPT. However, for correct diagnosis of PAPT, multiple system atrophy, spinocerebellar ataxia, progressive supranuclear palsy or adult-onset Alexander's disease should be carefully ruled out.

[A case of chronic active Epstein-Barr virus infection associated with recurrent cerebellar ataxia and skin eruptions].

A 62-year-old woman presented with subacute cerebellar ataxia, lymph node swelling and skin eruption. Laboratory tests revealed elevated titers of anti-VCA-IgG antibody and anti-EADR-IgG antibody, with Epstein-Barr virus (EBV) DNA detected from the blood and CSF by PCR. Since these data were highlighted with the diagnosis of chronic active EBV infection (CAEBV) and her ataxia improved concomitantly with the remission of other infectious mononucleosis-like symptoms, we supposed her ataxia is associated with CAEBV. Five years later, at the age of 67, her ataxia relapsed concurrently with skin eruptions, whereas MRI demonstrated progression of cerebellar atrophy. After high-dose intravenous methylprednisolone treatment, the clinical symptoms resolved. Initial infection of EBV in childhood often causes autoimmune acute cerebellitis but cerebellar ataxia has rarely been described in CAEBV. Furthermore, immunohistochemical analysis revealed a reactivity of the patient's serum and CSF on rat cerebellum, suggesting an autoimmune pathomechanism for the ataxia.