Expansion of the Parkinson disease-associated SNCA-Rep1 allele upregulates human alpha-synuclein in transgenic mouse brain.

Alpha-synuclein (SNCA) gene has been implicated in the development of rare forms of familial Parkinson disease (PD). Recently, it was shown that an increase in SNCA copy numbers leads to elevated levels of wild-type SNCA-mRNA and protein and is sufficient to cause early-onset, familial PD. A critical question concerning the molecular pathogenesis of PD is what contributory role, if any, is played by the SNCA gene in sporadic PD. The expansion of SNCA-Rep1, an upstream, polymorphic microsatellite of the SNCA gene, is associated with elevated risk for sporadic PD. However, whether SNCA-Rep1 is the causal variant and the underlying mechanism with which its effect is mediated by remained elusive. We report here the effects of three distinct SNCA-Rep1 variants in the brains of 72 mice transgenic for the entire human SNCA locus. Human SNCA-mRNA and protein levels were increased 1.7- and 1.25-fold, respectively, in homozygotes for the expanded, PD risk-conferring allele compared with homozygotes for the shorter, protective allele. When adjusting for the total SNCA-protein concentration (endogenous mouse and transgenic human) expressed in each brain, the expanded risk allele contributed 2.6-fold more to the SNCA steady-state than the shorter allele. Furthermore, targeted deletion of Rep1 resulted in the lowest human SNCA-mRNA and protein concentrations in murine brain. In contrast, the Rep1 effect was not observed in blood lysates from the same mice. These results demonstrate that Rep1 regulates human SNCA expression by enhancing its transcription in the adult nervous system and suggest that homozygosity for the expanded Rep1 allele may mimic locus multiplication, thereby elevating PD risk

Leucine-rich repeat kinase-2 (LRRK2) modulates paraquat-induced inflammatory sickness and stress phenotype

Background: Leucine-rich repeat kinase 2 (LRRK2) is a common gene implicated in Parkinson's disease (PD) and is also thought to be fundamentally involved in numerous immune functions. Thus, we assessed the role of LRRK2 in the context of the effects of the environmental toxicant, paraquat, that has been implicated in PD and is known to affect inflammatory processes. Methods: Male LRRK2 knockout (KO) and transgenic mice bearing the G2019S LRRK2 mutation (aged 6-8 months) or their littermate controls were exposed to paraquat (two times per week for 3 weeks), and sickness measures, motivational scores, and total home-cage activity levels were assessed. Following sacrifice, western blot and ELISA assays were performed to

Temporal changes in the epidemiology, management, and outcome from acute respiratory distress syndrome in European intensive care units: a comparison of two large cohorts

Background: Mortality rates for patients with ARDS remain high. We assessed temporal changes in the epidemiology and management of ARDS patients requiring invasive mechanical ventilation in European ICUs. We also investigated the association between ventilatory settings and outcome in these patients. Methods: This was a post hoc analysis of two cohorts of adult ICU patients admitted between May 1–15, 2002 (SOAP study, n = 3147), and May 8–18, 2012 (ICON audit, n = 4601 admitted to ICUs in the same 24 countries as the SOAP study). ARDS was defined retrospectively using the Berlin definitions. Values of tidal volume, PEEP, plateau pressure, and FiO2 corresponding to the most abnormal value of arterial PO2 were recorded prospectively every 24 h. In both studies, patients were followed for outcome until death, hospital discharge or for 60 days. Results: The frequency of ARDS requiring mechanical ventilation during the ICU stay was similar in SOAP and ICON (327[10.4%] vs. 494[10.7%], p = 0.793). The diagnosis of ARDS was established at a median of 3 (IQ: 1–7) days after admission in SOAP and 2 (1–6) days in ICON. Within 24 h of diagnosis, ARDS was mild in 244 (29.7%), moderate in 388 (47.3%), and severe in 189 (23.0%) patients. In patients with ARDS, tidal volumes were lower in the later (ICON) than in the earlier (SOAP) cohort. Plateau and driving pressures were also lower in ICON than in SOAP. ICU (134[41.1%] vs 179[36.9%]) and hospital (151[46.2%] vs 212[44.4%]) mortality rates in patients with ARDS were similar in SOAP and ICON. High plateau pressure (> 29 cmH2O) and driving pressure (> 14 cmH2O) on the first day of mechanical ventilation but not tidal volume (> 8 ml/kg predicted body weight [PBW]) were independently associated with a higher risk of in-hospital death. Conclusion: The frequency of and outcome from ARDS remained relatively stable between 2002 and 2012. Plateau pressure > 29 cmH2O and driving pressure > 14 cmH2O on the first day of mechanical ventilation but not tidal volume > 8 ml/kg PBW were independently associated with a higher risk of death. These data highlight the continued burden of ARDS and provide hypothesis-generating data for the design of future studies

Conversations With Dr. Oleh Hornykiewicz, Founding Father of the Dopamine Era in Parkinson's: How Do You Wish to Be Remembered?

On May 26, 2020, Dr. Oleh Hornykiewicz died at the age of 93 years. His twin discoveries in the early 1960s of dopamine deficiency in the brains of subjects with Parkinson's disease and the amelioration of patients' symptoms by levodopa therapy represent milestone events in the history of medicine. These breakthroughs enabled much-needed relief for millions of patients suffering from neurological disorders every year and have given rise to the field of dopamine signaling in the regulation of complex behaviors in primates. What did Dr. Hornykiewicz, who was actively engaged in research until shortly before his 91st birthday, wish to pass on to younger scientists? What were his thoughts regarding the elusive cause of Parkinson's disease? How did he wish to be remembered? Here, the authors, one a former student and the other an admired colleague, recall messages conveyed by Dr. Hornykiewicz in public lectures; they also share the content of conversations and letters exchanged with him since 2004, as he began to reflect on his legacy. Through Dr. Hornykiewicz's own words and writings, the picture emerges of an extraordinarily committed scientist, who was exemplary in his professional integrity, who knew how to deploy a gallous sense of humor, who displayed little patience for physicians offering advice, and who kept any sense of pride over his monumental contributions private. When asked at the age of 91 years about the secrets of his long and fulfilled career in neuroscience, he identified himself as “a mad scientist.…I am someone who continuously fantasizes. I am someone who chases fantastical ideas and who keeps on dreaming…”, and as a man who was supported by the loving companionship of his wife, Christine. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Decreased α-synuclein in cerebrospinal fluid of aged individuals and subjects with Parkinson’s disease.

There is ample biochemical, pathological, and genetic evidence that the metabolism of -synuclein (-syn) plays a crucial role in the pathogenesis of Parkinson disease (PD). To examine whether quantification of -syn in cerebrospinal fluid (CSF) is potentially informative in the diagnosis of PD, we developed a specific ELISA system and measured the concentration of -syn in CSF from 33 patients with PD (diagnosed according to UK PD Society Brain Bank criteria) and 38 control subjects including 9 neurologically healthy individuals. We found that PD patients had significantly lower -syn levels in their CSF than the control groups (p < 0.0001) even after adjusting for gender and age. Age was independently associated with lower -syn levels. Logistic regression analysis showed that reduction in CSF -syn served as a significant predictor of PD beyond age and gender alone (area under ROC curve, c = 0.882). Furthermore, we observed a close inverse correlation between -syn levels in CSF and assigned Hoehn and Yahr score in this cohort of 71 living subjects (p < 0.0001), even after adjusting for age. These findings identify in the quantification of -syn from CSF a potential laboratory marker to aid the clinical diagnosis of PD

Detection of oligomeric forms of α-synuclein protein in human plasma as a potential biomarker for Parkinson’s disease

To date there is no accepted clinical diagnostic test for Parkinson's disease (PD) based on biochemical analysis of blood or cerebrospinal fluid (CSF). -Synuclein (-syn) protein has been linked to the pathogenesis of PD with the discovery of mutations in the gene encoding -syn in familial cases with early-onset PD. Lewy bodies and Lewy neurites, which constitute the main pathological features in the brains of patients with sporadic PD and dementia with Lewy bodies, are formed by the conversion of soluble monomers of -syn into insoluble aggregates. We recently reported the presence of -syn in normal human blood plasma and in postmortem CSF. Here, we investigated whether -syn can be used as a biomarker for PD. We have developed a novel ELISA method that detects only oligomeric "soluble aggregates" of -syn. Using this ELISA, we report the presence of significantly elevated (P=0.002) levels of oligomeric forms of -syn in plasma samples obtained from 34 PD patients compared with 27 controls; 52% (95% confidence intervals 0.353–0.687) of the PD patients displayed signals >0.5 OD with our ELISA assay in comparison to only 14.8% (95% confidence intervals 0.014–0.281) for the control cases. An analysis of the test’s diagnostic value revealed a specificity of 0.852 (95% confidence intervals 0.662–0.958), sensitivity of 0.529 (95% confidence intervals 0.351–0.702) and a positive predictive value of 0.818 (95% confidence intervals 0.597–0.948). These observations offer new opportunities for developing diagnostic tests for PD and related diseases and for testing therapeutic agents aimed at preventing or reversing the aggregation of -syn.

Parallelism of analyte quantification in serially diluted CSF samples.

<p>Pooled CSF and three individual CSF samples were serially diluted by a factor of two for analysis. Protein concentrations were normalized for the 1:8 dilutions. A: aSyn, B: Aβ₄₂, C: DJ-1, D: t-tau protein.</p

A First Tetraplex Assay for the Simultaneous Quantification of Total α-Synuclein, Tau, β-Amyloid₄₂ and DJ-1 in Human Cerebrospinal Fluid

<div><p>The quantification of four distinct proteins (α-synuclein, β-amyloid_1-42, DJ-1, and total tau) in cerebrospinal fluid (CSF) has been proposed as a laboratory-based platform for the diagnosis of Parkinson’s disease (PD) and Alzheimer’s disease (AD). While there is some clinical utility in measuring these markers individually, their usage in routine clinical testing remains challenging, in part due to substantial overlap of concentrations between healthy controls and diseased subjects. In contrast, measurement of different analytes in a single sample from individual patients in parallel appears to considerably improve the accuracy of AD or PD diagnosis. Here, we report the development and initial characterization of a first, electrochemiluminescence-based multiplex immunoassay for the simultaneous quantification of all four proteins (‘tetraplex’) in as little as 50 μl of CSF. In analytical performance experiments, we assessed its sensitivity, spike-recovery rate, parallelism and dilution linearity as well as the intra- and inter-assay variability. Using our in-house calibrators, we recorded a lower limit of detection for α-synuclein, β-amyloid₄₂, DJ-1, and t-tau of 1.95, 1.24, 5.63, and 4.05 pg/ml, respectively. The corresponding, linear concentration range covered >3 orders of magnitude. In diluted CSF samples (up to 1:4), spike-recovery rates ranged from a low of 55% for β-amyloid₄₂ to a high of 98% for DJ-1. Hillslopes ranged from 1.03 to 1.30, and inter-assay variability demonstrated very high reproducibility. Our newly established tetraplex assay represents a significant technical advance for fluid-based biomarker studies in neurodegenerative disorders allowing the simultaneous measurement of four pivotal makers in single CSF specimens. It provides exceptional sensitivity, accuracy and speed.</p></div

Recovery rates of spiked calibrators into individual CSF samples.

<p>Recombinant calibrators were spiked at three different concentrations into four CSF samples. Concentrations of spike solutions and endogenous protein concentrations were determined in parallel. Recovery rates were calculated taking into account both the endogenous CSF concentration and the protein concentration of the spike solutions. A: aSyn, B: Aβ₄₂, C: DJ-1, D: t-tau protein.</p

Analytical sensitivity and lower limit of detection for tetraplex assay.

<p>Analytical sensitivity and lower limit of detection for tetraplex assay.</p