Mizuno Y

Pathologic and biochemical studies of juvenile parkinsonism linked to chromosome 6q

We report the results of pathologic and biochemical studies in a patient with 6q-linked autosomal recessive juvenile parkinsonism (AR-JP). Neuronal loss and gliosis were restricted to the substantia nigra and the locus ceruleus. No Lewy bodies were found, but neurofibrillary tangles and argyrophilic astrocytes were seen in the cerebral cortex and brainstem nuclei. The later findings, which have not been reported previously in AR-JP, suggest the pathologic heterogeneity of 6q-linked AR-JP.

Mitochondrial dysfunction associated with increased oxidative stress and α-synuclein accumulation in PARK2 iPSC-derived neurons and postmortem brain tissue

BackgroundParkinson’s disease (PD) is a neurodegenerative disease characterized by selective degeneration of dopaminergic neurons in the substantia nigra (SN). The familial form of PD, PARK2, is caused by mutations in the parkin gene. parkin-knockout mouse models show some abnormalities, but they do not fully recapitulate the pathophysiology of human PARK2.ResultsHere, we generated induced pluripotent stem cells (iPSCs) from two PARK2 patients. PARK2 iPSC-derived neurons showed increased oxidative stress and enhanced activity of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. iPSC-derived neurons, but not fibroblasts or iPSCs, exhibited abnormal mitochondrial morphology and impaired mitochondrial homeostasis. Although PARK2 patients rarely exhibit Lewy body (LB) formation with an accumulation of α-synuclein, α-synuclein accumulation was observed in the postmortem brain of one of the donor patients. This accumulation was also seen in the iPSC-derived neurons in the same patient.ConclusionsThus, pathogenic changes in the brain of a PARK2 patient were recapitulated using iPSC technology. These novel findings reveal mechanistic insights into the onset of PARK2 and identify novel targets for drug screening and potential modified therapies for PD.

Milestones in PD genetics.

Over the last 25 years, genetic findings have profoundly changed our views on the etiology of Parkinsons disease. Linkage studies and positional cloning strategies have identified mutations in a number of genes that cause several monogenic autosomal‐dominant or autosomal‐recessive forms of the disorder. Although most of these Mendelian forms of Parkinsons disease are rare, whole‐genome association studies have more recently provided convincing evidence that low‐penetrance variants in at least some of these, but also in several other genes, play a direct role in the etiology of the common sporadic disease as well. In addition, rare variants with intermediate‐effect strengths in genes such as Gauchers disease–associated glucocerebrosidase A have been discovered as important risk factors. “Next‐generation” sequencing technologies are expected by some to identify many more of these variants. Thus, an increasingly complex network of genes contributing in different ways to disease risk and progression is emerging. These findings may provide the “genetic entry points” to identify molecular targets and readouts necessary to design rational disease‐modifying treatments.

Adenosine A2A receptor antagonist istradefylline reduces daily OFF time in Parkinson's disease.

We evaluated the efficacy and safety of istradefylline, a selective adenosine A2A receptor antagonist administered as adjunctive treatment to levodopa for 12 weeks in a double‐blind manner in Parkinsons disease patients with motor complications in Japan.

Thalamic tremor Case reports and implications of the tremor-generating mechanism

Article abstract-We report two patients with unilateral resting and postural tremor of the upper limb as a delayed manifestation of thalamic stroke. Neuroradiologic examination showed a lesion in the posterolateral thalamic region in both patients, but with no obvious involvement of the brainstem, the cerebellum, or the cerebellar outflow tract to the thalamic ventrolateral nucleus. NEUROLOGY 1996;46: 75-79

PARK9-linked parkinsonism in eastern Asia: mutation detection in ATP13A2 and clinical phenotype.

PARK9, a form of autosomal recessive parkinsonism, or Kufor-Rakeb syndrome (KRS), is characterized by subacute or slowly progressive, juvenile-onset, levodopa-responsive parkinsonism, pyramidal signs, dementia, and supranuclear gaze palsy.1–5 Recently, ATP13A2 was identified as the causative gene for PARK9 in Chilean and Jordanian families.4 This gene contains 29 exons encoding a lysosomal type 5 P-type ATPase. Six mutations have been reported in only five probands so far.4,5 Here, we describe a Japanese patient with KRS with a novel mutation who developed early onset parkinsonism, dementia, and other features. We also describe PET findings of PARK9 -linked parkinsonism. ### Methods. Haplotype analysis was conducted in 117 (mainly Japanese) patients with early onset (≤50, 26.8 ± 11.7 years, mean ± SD) parkinsonism. Among them, 14 patients had dementia. Patients who exhibited homozygosity on PARK9 locus by haplotype analysis underwent direct sequencing for all 29 exons (e-Methods on the Neurology ® Web site at www.neurology.org); the remaining patients underwent direct sequencing for exons 13, 16, and 26, in which mutations …

Pramipexole in patients with early Parkinson's disease (PROUD): a randomised delayed-start trial

Summary Background In models of dopaminergic neuronal loss, the dopamine agonist pramipexole has exhibited neuroprotective properties. The Pramipexole On Underlying Disease (PROUD) study was designed to identify whether early versus delayed pramipexole initiation has clinical and neuroimaging benefits in patients with Parkinsons disease (PD). Methods Between May 24, 2006, and April 22, 2009, at 98 centres, we recruited patients with PD diagnosed within 2 years and aged 30–79 years. We randomly assigned eligible patients (ratio 1:1), by a centralised, computerised randomisation schedule, to receive double-blind either placebo or pramipexole (1·5 mg a day) and followed them up for 15 months. At 9 months, or as early as 6 months if considered necessary, placebo recipients were assigned to pramipexole. In a neuroimaging substudy, striatal dopamine-transporter binding was assessed by SPECT. All patients, investigators, and independent raters were masked to study treatment. The primary endpoint was the 15-month change from baseline in total score on the unified Parkinsons disease rating scale (UPDRS). This trial is registered with ClinicalTrials.gov, number NCT00321854. Findings Of 535 patients, 261 were randomly assigned to receive pramipexole and 274 to receive placebo. At 15 months (n=411), adjusted mean change in UPDRS total score showed no significant difference between early and delayed pramipexole (−0·4 points, 95% CI −2·2 to 1·4, p=0·65). 62 patients in the early pramipexole group and 61 patients in the delayed pramipexole group were included in the neuroimaging substudy, for which the adjusted mean 15-month change in striatal 123I-FP-CIT binding was −15·1% (SE 2·1) for early and −14·6% (2·0) for delayed pramipexole (difference −0·5 percentage points, 95% CI −5·4 to 4·4, p=0·84). Overall, 180 (81%) of patients given early pramipexole and 179 (84%) patients given delayed pramipexole reported adverse events (most frequently nausea), and 22 (10%) patients in the early pramipexole group and 17 (8%) in the delayed pramipexole group had serious events, two of which (hallucinations and orthostatic hypotension) were deemed related to study drug. Interpretation By clinical and neuroimaging measures, pramipexole showed little evidence differentiating 15-month usage from usage delayed for 6–9 months. The results do not support the hypothesis that pramipexole has disease-modifying effects. Funding Boehringer Ingelheim GmbH.

Mn SOD activity and protein in a patient with chromosome 6-linked autosomal recessive parkinsonism in comparison with Parkinson's disease and control

We report Mn superoxide dismutase (SOD) protein and activity in a patient with familial autosomal recessive Lewy body-negative parkinsonism in comparison with patients with sporadic Parkinsons disease (PD) and controls. We recently proved linkage of this family with markers of chromosome 6 at 6q25.2-27, which included the Mn SOD gene. We used a novel polymorphic mutation at -9 position of the signal peptide of the Mn SOD precursor protein, which caused valine to alanine substitution. All the affected members of this family showed homozygosity for alanine, whereas nonaffected members, sporadic PD patients, and the control subjects studied showed either heterozygosity of alanine and valine or homozygosity of valine. The Mn SOD activity of this familial patient was the highest among the PD patients and the control subjects studied, and an abundant expression of Mn SOD was found in the substantia nigra. The molecular weight of Mn SOD protein by Western blotting of this patient was essentially similar to that of PD patients and the control subjects. High Mn SOD activity may constitute a genetic risk factor in this familial patient. The difference in the signal peptide sequence may affect the expression of Mn SOD within mitochondria; however, it is unlikely that loss of function type Mn SOD mutation is the cause of this familial parkinsonism. Mn SOD in sporadic PD patients was similar to that in controls.

Extended-release pramipexole in advanced Parkinson disease A randomized controlled trial

Background: In advanced Parkinson disease (PD), immediate-release pramipexole, taken 3 times daily, improves symptoms and quality of life. A once-daily extended-release formulation may be an effective and simple alternative therapy. Methods: For a multicenter randomized, double-blind, parallel trial of extended- and immediate-release pramipexole vs placebo, patients experiencing motor fluctuations while taking levodopa underwent flexible study drug titration and then maintenance at optimized dosage (0.375–4.5 mg/day). The primary endpoint was a change in the Unified Parkinsons Disease Rating Scale (UPDRS) part II+III score at 18 weeks, with further assessments at 33 weeks in a subset of patients. Adverse events were recorded throughout. Results: Among 507 patients in the 18-week analyses, UPDRS II+III scores decreased (from baseline means of 40.0–41.7) by an adjusted mean of −11.0 for extended-release pramipexole and −12.8 for immediate-release pramipexole vs −6.1 for placebo (p = 0.0001 and p < 0.0001) and off-time decreased (from baseline means of 5.8–6.0 hours/day) by an adjusted mean of −2.1 and −2.5 vs −1.4 hours/day (p = 0.0199 and p < 0.0001). Other outcomes were largely corroborative, including a significant improvement in early morning off symptoms. Among 249 pramipexole patients completing 33 weeks, UPDRS II+III and off-time findings showed ≤10.1% change from 18-week values. Both formulations were well-tolerated. Conclusions: Extended-release pramipexole significantly improved UPDRS score and off-time compared with placebo, with similar efficacy, tolerability, and safety of immediate-release pramipexole compared with placebo. Classification of evidence: This study provides Class I evidence that the extended-release form of pramipexole, taken once daily, is efficacious as an adjunct to levodopa in advanced PD. Neurology® 2011;77:767–774

Diagnostic accuracy of 123I-meta-iodobenzylguanidine myocardial scintigraphy in dementia with Lewy bodies: a multicenter study.

Background and Purpose Dementia with Lewy bodies (DLB) needs to be distinguished from Alzheimer’s disease (AD) because of important differences in patient management and outcome. Severe cardiac sympathetic degeneration occurs in DLB, but not in AD, offering a potential system for a biological diagnostic marker. The primary aim of this study was to investigate the diagnostic accuracy, in the ante-mortem differentiation of probable DLB from probable AD, of cardiac imaging with the ligand 123I-meta-iodobenzylguanidine (MIBG) which binds to the noradrenaline reuptake site, in the first multicenter study. Methods We performed a multicenter study in which we used 123I-MIBG scans to assess 133 patients with clinical diagnoses of probable (n = 61) or possible (n = 26) DLB or probable AD (n = 46) established by a consensus panel. Three readers, unaware of the clinical diagnosis, classified the images as either normal or abnormal by visual inspection. The heart-to-mediastinum ratios of 123I-MIBG uptake were also calculated using an automated region-of-interest based system. Results Using the heart-to-mediastinum ratio calculated with the automated system, the sensitivity was 68.9% and the specificity was 89.1% to differentiate probable DLB from probable AD in both early and delayed images. By visual assessment, the sensitivity and specificity were 68.9% and 87.0%, respectively. In a subpopulation of patients with mild dementia (MMSE ≥ 22, n = 47), the sensitivity and specificity were 77.4% and 93.8%, respectively, with the delayed heart-to-mediastinum ratio. Conclusions Our first multicenter study confirmed the high correlation between abnormal cardiac sympathetic activity evaluated with 123I-MIBG myocardial scintigraphy and a clinical diagnosis of probable DLB. The diagnostic accuracy is sufficiently high for this technique to be clinically useful in distinguishing DLB from AD, especially in patients with mild dementia.