The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons

Background

Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified.

Methods

Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils.

Results

We first identified specific non-coding variants in CTSB that drive the association with PD and are linked to changes in brain CTSB expression levels. Using iPSC-derived dopaminergic neurons we then find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1) activity, and leads to an accumulation of lysosomal content. Moreover, in cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. Similarly, in midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition or knockout potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein.

Conclusions

The results of our genetic and functional studies indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

The use of predator tags to explain reversal movement patterns in Atlantic salmon smolts (Salmo salar L.)

Acoustic telemetry has seen a rapid increase in utility and sophistication in recent years and is now used extensively to assess the behavior and survival rates of many aquatic animals, including the Atlantic salmon. As part of the salmon's complex life cycle, salmon smolts are thought to make a unidirectional migration from fresh water to the sea, which is initiated by changes in their physiology. However, some tag movement patterns do not conform with this and can be difficult to explain, particularly if the tagged fish has been eaten by a predator. This study combines the use of predator tags with machine learning techniques to understand the fate of migrating salmon smolts and thereby improve estimates for migration success. Over 3 years between 2020 and 2022, 217 salmon smolts (including wild and hatchery-reared ranched fish) were acoustically tagged and released into an embayment on the west coast of Ireland. Some tagged smolts were observed to return from the estuary back into a saline lagoon through which they had already migrated. To distinguish between the movement of a salmon smolt and that of a predator, predator tags were deployed in migrating smolts in 2021 and 2022. The addition of a temperature sensor in 2022 enabled the determination of predator type causing the returning movement. A significant number of predator tags were triggered, and the patterns of movement associated with these triggered tags were then used with two types of machine learning algorithms (hierarchical cluster analysis and random forest) to identify and validate the behavior of smolts tagged without extra sensors. Both models produced the same outputs, grouping smolts tagged with predator tags with smolts tagged without the additional sensors but showing similar movements. A mammalian predator was identified as the cause of most reversal movement, and hatchery-reared ranched smolts were found to be more likely predated upon by this predator than wild smolts within the lake and the estuary. However, overall migration success estimates were similar for both wild and hatchery-reared ranched fish. This study highlights the value of predator tags as an essential tool in the overall validation of detection data.

The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons

Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified. Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils. We find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1 ) activity, and leads to an accumulation of lysosomal content. In cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. In midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein. These results indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

Association of Rare Variants in ARSA with Parkinson's Disease

BACKGROUND

Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA remains unclear.

OBJECTIVES

To study rare ARSA variants in PD.

METHODS

To study rare ARSA variants (minor allele frequency < 0.01) in PD, we performed burden analyses in six independent cohorts with 5801 PD patients and 20,475 controls, followed by a meta-analysis.

RESULTS

We found evidence for associations between functional ARSA variants and PD in four cohorts (P ≤ 0.05 in each) and in the meta-analysis (P = 0.042). We also found an association between loss-of-function variants and PD in the United Kingdom Biobank cohort (P = 0.005) and in the meta-analysis (P = 0.049). These results should be interpreted with caution as no association survived multiple comparisons correction. Additionally, we describe two families with potential co-segregation of ARSA p.E382K and PD.

CONCLUSIONS

Rare functional and loss-of-function ARSA variants may be associated with PD. Further replications in large case-control/familial cohorts are required. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A blood-based marker of mitochondrial DNA damage in Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, and neuroprotective or disease-modifying interventions remain elusive. High-throughput markers aimed at stratifying patients on the basis of shared etiology are required to ensure the success of disease-modifying therapies in clinical trials. Mitochondrial dysfunction plays a prominent role in the pathogenesis of PD. Previously, we found brain region-specific accumulation of mitochondrial DNA (mtDNA) damage in PD neuronal culture and animal models, as well as in human PD postmortem brain tissue. To investigate mtDNA damage as a potential blood-based marker for PD, we describe herein a PCR-based assay (Mito DNADX) that allows for the accurate real-time quantification of mtDNA damage in a scalable platform. We found that mtDNA damage was increased in peripheral blood mononuclear cells derived from patients with idiopathic PD and those harboring the PD-associated leucine-rich repeat kinase 2 (LRRK2) G2019S mutation in comparison with age-matched controls. In addition, mtDNA damage was elevated in non-disease-manifesting LRRK2 mutation carriers, demonstrating that mtDNA damage can occur irrespective of a PD diagnosis. We further established that Lrrk2 G2019S knock-in mice displayed increased mtDNA damage, whereas Lrrk2 knockout mice showed fewer mtDNA lesions in the ventral midbrain, compared with wild-type control mice. Furthermore, a small-molecule kinase inhibitor of LRRK2 mitigated mtDNA damage in a rotenone PD rat midbrain neuron model and in idiopathic PD patient-derived lymphoblastoid cell lines. Quantifying mtDNA damage using the Mito DNADX assay may have utility as a candidate marker of PD and for measuring the pharmacodynamic response to LRRK2 kinase inhibitors.

Association of rare variants in ARSA with Parkinson's disease

Background

Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA , which encodes for the enzyme arylsulfatase A, remains controversial.

Objectives

To evaluate the association between rare ARSA variants and PD.

Methods

To study possible association of rare variants (minor allele frequency<0.01) in ARSA with PD, we performed burden analyses in six independent cohorts with a total of 5,801 PD patients and 20,475 controls, using optimized sequence Kernel association test (SKAT-O), followed by a meta-analysis.

Results

We found evidence for an association between functional ARSA variants and PD in four independent cohorts (P≤0.05 in each) and in the meta-analysis (P=0.042). We also found an association between loss-of-function variants and PD in the UKBB cohort (P=0.005) and in the meta-analysis (P=0.049). However, despite replicating in four independent cohorts, these results should be interpreted with caution as no association survived correction for multiple comparisons. Additionally, we describe two families with potential co-segregation of the ARSA variant p.E384K and PD.

Conclusions

Rare functional and loss-of-function ARSA variants may be associated with PD. Further replication in large case-control cohorts and in familial studies is required to confirm these associations.

Embracing Monogenic Parkinson's Disease: The MJFF Global Genetic PD Cohort

BACKGROUND

As gene-targeted therapies are increasingly being developed for Parkinson's disease (PD), identifying and characterizing carriers of specific genetic pathogenic variants is imperative. Only a small fraction of the estimated number of subjects with monogenic PD worldwide are currently represented in the literature and availability of clinical data and clinical trial-ready cohorts is limited.

OBJECTIVE

The objectives are to (1) establish an international cohort of affected and unaffected individuals with PD-linked variants; (2) provide harmonized and quality-controlled clinical characterization data for each included individual; and (3) further promote collaboration of researchers in the field of monogenic PD.

METHODS

We conducted a worldwide, systematic online survey to collect individual-level data on individuals with PD-linked variants in SNCA, LRRK2, VPS35, PRKN, PINK1, DJ-1, as well as selected pathogenic and risk variants in GBA and corresponding demographic, clinical, and genetic data. All registered cases underwent thorough quality checks, and pathogenicity scoring of the variants and genotype-phenotype relationships were analyzed.

RESULTS

We collected 3888 variant carriers for our analyses, reported by 92 centers (42 countries) worldwide. Of the included individuals, 3185 had a diagnosis of PD (ie, 1306 LRRK2, 115 SNCA, 23 VPS35, 429 PRKN, 75 PINK1, 13 DJ-1, and 1224 GBA) and 703 were unaffected (ie, 328 LRRK2, 32 SNCA, 3 VPS35, 1 PRKN, 1 PINK1, and 338 GBA). In total, we identified 269 different pathogenic variants; 1322 individuals in our cohort (34%) were indicated as not previously published.

CONCLUSIONS

Within the MJFF Global Genetic PD Study Group, we (1) established the largest international cohort of affected and unaffected individuals carrying PD-linked variants; (2) provide harmonized and quality-controlled clinical and genetic data for each included individual; (3) promote collaboration in the field of genetic PD with a view toward clinical and genetic stratification of patients for gene-targeted clinical trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

GALC variants affect galactosylceramidase enzymatic activity and risk of Parkinson’s disease

The association between glucocerebrosidase (GCase), encoded by GBA, and Parkinson’s disease highlights the role of the lysosome in Parkinson’s disease pathogenesis. Genome-wide association studies (GWAS) in Parkinson’s disease have revealed multiple associated loci, including the GALC locus on chromosome 14. GALC encodes the lysosomal enzyme galactosylceramidase (GalCase), which plays a pivotal role in the glycosphingolipid metabolism pathway. It is still unclear whether GALC is the gene driving the association in the chromosome 14 locus, and if so, by which mechanism.

We first aimed to examine whether variants in the GALC locus and across the genome are associated with GalCase activity. We performed a GWAS in two independent cohorts from a)Columbia University and b)the Parkinson’s Progression Markers Initiative study, followed by a meta-analysis with a total of 976 Parkinson’s disease patients and 478 controls with available data on GalCase activity. We further analyzed the effects of common GALC variants on expression and GalCase activity using genomic colocalization methods. Mendelian randomization was used to study whether GalCase activity may be causal in Parkinson’s disease. To study the role of rare GALC variants we analyzed sequencing data from 5,028 Parkinson’s disease patients and 5,422 controls. Additionally, we studied the functional impact of GALC knock-out on alpha-synuclein accumulation and on GCase activity in neuronal cell models and performed in silico structural analysis of common GALC variants associated with altered GalCase activity.

The top hit in Parkinson's disease GWAS in the GALC locus, rs979812, is associated with increased GalCase activity (b = 1.2; se = 0.06; p = 5.10E-95). No other variants outside the GALC locus were associated with GalCase activity. Colocalization analysis demonstrated that rs979812 was also associated with increased GalCase expression. Mendelian randomization suggested that increased GalCase activity may be causally associated with Parkinson’s disease (b = 0.025, se = 0.007, p = 0.0008). We did not find an association between rare GALC variants and Parkinson’s disease. GALC knockout using CRISPR-Cas9 did not lead to alpha-synuclein accumulation, further supporting that increased rather than reduced GalCase levels may be associated with Parkinson’s disease. The structural analysis demonstrated that the common variant p.I562T may lead to improper maturation of GalCase affecting its activity.

Our results nominate GALC as the gene associated with Parkinson’s disease in this locus and suggest that the association of variants in the GALC locus may be driven by their effect of increasing GalCase expression and activity. Whether altering GalCase activity could be considered as a therapeutic target should be further studied.

Plasma Glucosylsphingosine in GBA1 Mutation Carriers with and without Parkinson's Disease

Background

Biallelic mutations in the GBA1 gene encoding glucocerebrosidase cause Gaucher's disease, whereas heterozygous carriers are at risk for Parkinson's disease (PD). Glucosylsphingosine is a clinically meaningful biomarker of Gaucher's disease but could not be assayed previously in heterozygous GBA1 carriers.

Objective

The aim of this study was to assess plasma glucosylsphingosine levels in GBA1 N370S carriers with and without PD.

Methods

Glucosylsphingosine, glucosylceramide, and four other lipids were quantified in plasma from N370S heterozygotes with (n = 20) or without (n = 20) PD, healthy controls (n = 20), idiopathic PD (n = 20), and four N370S homozygotes (positive controls; Gaucher's/PD) using quantitative ultra‐performance liquid chromatography tandem mass spectrometry.

Results

Plasma glucosylsphingosine was significantly higher in N370S heterozygotes compared with noncarriers, independent of disease status. As expected, Gaucher's/PD cases showed increases in both glucocerebrosidase substrates, glucosylsphingosine and glucosylceramide.

Conclusions

Plasma glucosylsphingosine accumulation in N370S heterozygotes shown in this study opens up its future assessment as a clinically meaningful biomarker of GBA1‐PD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

1505 EASiE: ENT and Airway Simulation in Emergencies

Aim

A literature review of undergraduate ENT teaching found that most final year medical students and junior doctors did not feel adequately prepared for clinical practice in ENT. Other surveys found junior doctors lack confidence in recognising or initiating management in patients with blocked tracheostomies. To improve this, we ran a simulation session designed to replicate airway emergencies that junior doctors should be able to manage. The aim was to improve confidence in and knowledge of basic management of airway emergencies, including tracheostomies.

Method

Groups of 4-6 final year medical students participated in 3 scenarios: 2 tracheostomy-related and 1 partially compromised airway. The students had attended a session introducing tracheostomies and the algorithms produced by the National Tracheostomy Safety Project for tracheostomy emergencies. A semi-structured debrief followed each scenario, highlighting key learning points. The students completed a pre- and post-session questionnaire, rating confidence in several domains related to the scenarios.

Results

Of 24 participants, the percentage of students who felt confident or very confident in the following domains were compared pre- and post-simulation respectively: recognising a potential airway problem (0% vs 71%); identifying an altered airway (0% vs 75%); managing a potentially compromised surgical airway (4% vs 71%); initially managing a compromised airway (8% vs 67%); and identifying when to escalate with a potential airway problem (25% vs 96%).

Conclusions

Simulation is a valuable tool that can be used to improve both knowledge and confidence in managing potential airway problems in final year medical students. This supports findings from other studies.

1617 SOCS: Surgical On-Call Simulation

Introduction

Simulation is a well-known method of effectively teaching Medical students. The majority of the simulation scenarios are related to Medicine. Surgical simulation is a gap within the curriculum, especially Surgical on-call simulations. To improve this, we ran simulation sessions designed to replicate a General Surgery themed on-call shift that junior doctors should be able to manage. We aimed to improve confidence in clinical prioritisation and confidence in being an on-call Junior doctor, managing the most common on-call surgical tasks.

Method

Groups of 3-4 final year Medical students participated in a 2 hour-long simulated “on-call” shift, throughout the hospital. There were 8 scenarios, which ranged from prescribing to acute clinical scenarios. Students were given bleeps and were called at set times. They had to receive/give handovers and prioritise tasks according to clinical importance. A debrief following the session focussed on prioritisation and highlighted key learning points. The students completed a pre- and post-session questionnaire as assessment.

Results

The percentage of students who felt confident or very confident in the following domains were compared pre- and post-simulation respectively: confidence in clinical prioritisation (17% vs 86%); confidence in prescribing medication (0% vs 14%); confidence in escalation to seniors (33% vs 71%). 87.5% of the participants felt the session was an effective way to learn how to prioritise clinical tasks, and 100% felt this an effective way to learn about common General Surgical queries whilst on-call.

Conclusions

This project demonstrates how simulation is effective in improving confidence in prioritisation and knowledge within clinical practice, especially surgery.

1438 The Past, Present and Future Management of Complex Chyle Fistulae

Background

Chyle leak/fistula is a rare complication of oesophageal surgery, usually consequent on an unintended breach of the thoracic duct, its tributaries, or the cisterna chyli. For high volume persistent leaks further surgery has been the traditional approach, however two cases have resulted in a new management approach at this Centre.

Case Series

The first patient, a 49-year-old, developed high volume drain output post three stage oesophagectomy. His jejunostomy feeding was discontinued, total parenteral nutrition and a somatostatin analogue, were commenced. Despite these measures, the drain output remained &gt;1.5litres per day and an exploratory thoracotomy was performed. The second patient, an 81-year-old underwent a transhiatal-oesophagectomy. On postoperative day 10 he developed acute onset shortness of breath, CXR demonstrated a large left sided pleural effusion. CT thorax demonstrated multiloculated complex pleural effusions. US guided pig tail drain was placed in the largest targetable effusion. The fluid was chylous in appearance. In both cases, an interventional radiological approach, not previously performed at this centre, provided definitive management. Lymphangiography was performed via injection of 1mL of Lipoidol® every 5 minutes into the inguinal lymph nodes to identify the cisterna chyli. A guidewire was advanced via the cisterna chyli with coils and glue used to embolize the leaking tracts.

Discussion

The lessons from this experience provide an algorithm for the management of chyle leaks, that will change practice at this centre. Embolization or disruption of thoracic duct and cisterna chyli leaks will be first line therapy for complex chyle leaks, with surgery reserved for where this fails.

Effect of Urate-Elevating Inosine on Early Parkinson Disease Progression: The SURE-PD3 Randomized Clinical Trial

Importance

Urate elevation, despite associations with crystallopathic, cardiovascular, and metabolic disorders, has been pursued as a potential disease-modifying strategy for Parkinson disease (PD) based on convergent biological, epidemiological, and clinical data.

Objective

To determine whether sustained urate-elevating treatment with the urate precursor inosine slows early PD progression.

Design, Participants, and Setting

Randomized, double-blind, placebo-controlled, phase 3 trial of oral inosine treatment in early PD. A total of 587 individuals consented, and 298 with PD not yet requiring dopaminergic medication, striatal dopamine transporter deficiency, and serum urate below the population median concentration (<5.8 mg/dL) were randomized between August 2016 and December 2017 at 58 US sites, and were followed up through June 2019.

Interventions

Inosine, dosed by blinded titration to increase serum urate concentrations to 7.1-8.0 mg/dL (n = 149) or matching placebo (n = 149) for up to 2 years.

Main Outcomes and Measures

The primary outcome was rate of change in the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS; parts I-III) total score (range, 0-236; higher scores indicate greater disability; minimum clinically important difference of 6.3 points) prior to dopaminergic drug therapy initiation. Secondary outcomes included serum urate to measure target engagement, adverse events to measure safety, and 29 efficacy measures of disability, quality of life, cognition, mood, autonomic function, and striatal dopamine transporter binding as a biomarker of neuronal integrity.

Results

Based on a prespecified interim futility analysis, the study closed early, with 273 (92%) of the randomized participants (49% women; mean age, 63 years) completing the study. Clinical progression rates were not significantly different between participants randomized to inosine (MDS-UPDRS score, 11.1 [95% CI, 9.7-12.6] points per year) and placebo (MDS-UPDRS score, 9.9 [95% CI, 8.4-11.3] points per year; difference, 1.26 [95% CI, -0.59 to 3.11] points per year; P = .18). Sustained elevation of serum urate by 2.03 mg/dL (from a baseline level of 4.6 mg/dL; 44% increase) occurred in the inosine group vs a 0.01-mg/dL change in serum urate in the placebo group (difference, 2.02 mg/dL [95% CI, 1.85-2.19 mg/dL]; P<.001). There were no significant differences for secondary efficacy outcomes including dopamine transporter binding loss. Participants randomized to inosine, compared with placebo, experienced fewer serious adverse events (7.4 vs 13.1 per 100 patient-years) but more kidney stones (7.0 vs 1.4 stones per 100 patient-years).

Conclusions and Relevance

Among patients recently diagnosed as having PD, treatment with inosine, compared with placebo, did not result in a significant difference in the rate of clinical disease progression. The findings do not support the use of inosine as a treatment for early PD.

Trial Registration

ClinicalTrials.gov Identifier: NCT02642393.

LRRK2 p.M1646T is associated with glucocerebrosidase activity and with Parkinson's disease

The LRRK2 p.G2019S Parkinson's disease (PD) variant is associated with elevated glucocerebrosidase (GCase) activity in peripheral blood. We aimed to evaluate the association of other LRRK2 variants with PD and its association with GCase activity. LRRK2 and GBA were fully sequenced in 1123 PD patients and 576 controls from the Columbia and PPMI cohorts, in which GCase activity was measured in dried blood spots by liquid chromatography-tandem mass spectrometry. LRRK2 p.M1646T was associated with increased GCase activity in the Columbia University cohort (β = 1.58, p = 0.0003), and increased but not significantly in the PPMI cohort (β = 0.29, p = 0.58). p.M1646T was associated with PD (odds ratio = 1.18, 95% confidence interval = 1.09-1.28, p = 7.33E-05) in 56,306 PD patients and proxy-cases, and 1.4 million controls. Our results suggest that the p.M1646T variant is associated with risk of PD with a small effect and with increased GCase activity in peripheral blood.

Cytokines and Gaucher Biomarkers in Glucocerebrosidase Carriers with and Without Parkinson Disease

BACKGROUND

Homozygous and compound heterozygous variants in glucocerebrosidase (GBA) can cause Gaucher disease (GD), whereas heterozygous variants increase the risk of developing Parkinson's disease (PD). GD patients display altered peripheral immune proteins. However, it is unknown if these are altered in GBA carriers with PD.

OBJECTIVES

To determine whether plasma cytokines and immune biomarkers associated with GD are also altered in GBA carriers with or without PD.

METHODS

Inflammatory cytokines and established GD biomarkers, ferritin, CD162, CCL18, and chitotriosidase (28 biomarkers) were measured in GBA pathogenic variant carriers with (n = 135) and without (n = 83) PD, and non-carriers with (n = 75) and without PD (n = 77).

RESULTS

PD patients with biallelic pathogenic variants in GBA had elevated plasma levels of ferritin, CCL18, and MIP1α. These biomarkers were not elevated in heterozygous GBA carriers.

CONCLUSION

GD plasma biomarkers are not promising candidates for stratifying the risk for PD in carriers of heterozygous GBA pathogenic variants. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Association study of DNAJC13, UCHL1, HTRA2, GIGYF2, and EIF4G1 with Parkinson's disease

Rare mutations in genes originally discovered in multigenerational families have been associated with increased risk of Parkinson's disease (PD). The involvement of rare variants in DNAJC13, UCHL1, HTRA2, GIGYF2, and EIF4G1 loci has been poorly studied or has produced conflicting results across cohorts. However, they are still being often referred to as "PD genes" and used in different models. To further elucidate the role of these 5 genes in PD, we fully sequenced them using molecular inversion probes in 2408 patients with PD and 3444 controls from 3 different cohorts. A total of 788 rare variants were identified across the 5 genes and 3 cohorts. Burden analyses and optimized sequence Kernel association tests revealed no significant association between any of the genes and PD after correction for multiple comparisons. Our results do not support an association of the 5 tested genes with PD. Combined with previous studies, it is unlikely that any of these genes plays an important role in PD. Their designation as "PARK" genes should be reconsidered.

Variants in the Niemann-Pick type C gene NPC1 are not associated with Parkinson's disease

Biallelic variants in NPC1, a gene coding for a lysosomal transmembrane protein involved in cholesterol trafficking, may cause Niemann-Pick disease type C (NPC). A few cases of NPC1 variant carriers with Parkinson's disease (PD) have been reported. In addition, pathologic studies have demonstrated phosphorylated alpha-synuclein and Lewy pathology in brains of NPC patients. Therefore, we aimed to examine whether NPC1 genetic variants may be associated with PD. Full sequencing of NPC1 was performed in 2657 PD patients and 3647 controls from 3 cohorts, using targeted sequencing with molecular inversion probes. A total of 9 common variants and 126 rare variants were identified across the 3 cohorts. To examine their association with PD, regression models adjusted for age, sex, and origin were performed for common variants, and optimal sequence Kernel association test (SKAT-O) was performed for rare variants. After correction for multiple comparisons, common and rare NPC1 variants were not associated with PD. Our results do not support a link between heterozygous variants in NPC1 and PD.

Self-rated health of Middle Eastern immigrants in the US: a national study

OBJECTIVES

The aim of the study was to examine self-rated health (SRH) of Middle Eastern immigrants in the US compared with US-born non-Hispanic whites and to examine factors associated with fair/poor SRH among Middle Eastern immigrants in the US.

STUDY DESIGN

We used a cross-sectional design to analyze the National Health Interview Survey from 2001 to 2015.

METHODS

Secondary survey analysis procedures were conducted using the SAS program, with a total of 3,966 Middle Eastern and 731,285 US-born non-Hispanic whites. Descriptive statistics and regression analyses were used.

RESULTS

Middle Eastern immigrants had significantly higher rates of fair/poor SRH than US-born whites across the three survey waves. Reporting symptoms of serious psychological distress, older age (60+ years), current alcohol-drinking status, and having a family member with disability were the factors associated significantly with higher odds of reporting fair/poor SRH in Middle Eastern immigrants, whereas education was a protecting factor of fair/poor SRH.

CONCLUSIONS

This study indicates that Middle Eastern immigrants are one of the US immigrant populations that report poor health status, which reveals the need for health policy attention to reduce health disparities.

Association of Low Lysosomal Enzymes Activity With Brain Arterial Dilatation

Background and Purpose- Absent or diminished α-galactosidase A (GLA) and acid α-glucosidase (GAA) enzyme activity are core features of Fabry and Pompe disease, respectively. Patients with Fabry or Pompe disease may have dilated intracranial arteries but whether lower GLA or GAA enzyme activity relates to brain arterial dilatation in other populations is unknown. Methods- Participants included Parkinson disease patients and nonblood-related controls, whose GLA and GAA enzymatic activities were measured in dried blood spots. Independent readers measured the axial arterial diameter of the ascending portion of the cavernous internal carotid arteries and the most proximal segment of the basilar artery in T2 black voids. Linear regression models were built to investigate the relationship between brain arterial diameters and lysosomal enzymatic activities. Results- The cohort included 107 participants (mean age, 66.5±10.3; 67% men). In an adjusted linear regression model, lower GLA activity was associated with larger brain arterial diameters (B=0.50±0.23, P=0.03). The strength of association was the greatest for the basilar artery diameter (B=0.80±0.33, P=0.02). Similarly, lower GAA activity was associated with an increased basilar arterial diameter (B=0.73±0.35, P=0.04). Conclusions- Lower GLA and GAA enzymatic activities were associated with larger brain arterial diameters, particularly the basilar artery diameter. Lower lysosomal enzymatic function in patients without Fabry or Pompe disease may play a role in brain arterial dilatation.

Mental health nurses' attitudes, experience, and knowledge regarding routine physical healthcare: systematic, integrative review of studies involving 7,549 nurses working in mental health settings

Background

There has been a recent growth in research addressing mental health nurses’ routine physical healthcare knowledge and attitudes. We aimed to systematically review the empirical evidence about i) mental health nurses’ knowledge, attitudes, and experiences of physical healthcare for mental health patients, and ii) the effectiveness of any interventions to improve these aspects of their work.

Methods

Systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Multiple electronic databases were searched using comprehensive terms. Inclusion criteria: English language papers recounting empirical studies about: i) mental health nurses’ routine physical healthcare-related knowledge, skills, experience, attitudes, or training needs; and ii) the effectiveness of interventions to improve any outcome related to mental health nurses’ delivery of routine physical health care for mental health patients. Effect sizes from intervention studies were extracted or calculated where there was sufficient information. An integrative, narrative synthesis of study findings was conducted.

Results

Fifty-one papers covering studies from 41 unique samples including 7549 mental health nurses in 14 countries met inclusion criteria. Forty-two (82.4%) papers were published since 2010. Eleven were intervention studies; 40 were cross-sectional. Observational and qualitative studies were generally of good quality and establish a baseline picture of the issue. Intervention studies were prone to bias due to lack of randomisation and control groups but produced some large effect sizes for targeted education innovations. Comparisons of international data from studies using the Physical Health Attitudes Scale for Mental Health Nursing revealed differences across the world which may have implications for different models of student nurse preparation.

Conclusions

Mental health nurses’ ability and increasing enthusiasm for routine physical healthcare has been highlighted in recent years. Contemporary literature provides a base for future research which must now concentrate on determining the effectiveness of nurse preparation for providing physical health care for people with mental disorder, determining the appropriate content for such preparation, and evaluating the effectiveness both in terms of nurse and patient- related outcomes. At the same time, developments are needed which are congruent with the needs and wants of patients.

Electronic supplementary material

The online version of this article (10.1186/s12912-019-0339-x) contains supplementary material, which is available to authorized users.

SMPD1 mutations, activity, and α-synuclein accumulation in Parkinson's disease

BACKGROUND

SMPD1 (acid-sphingomyelinase) variants have been associated with Parkinson's disease in recent studies. The objective of this study was to further investigate the role of SMPD1 mutations in PD.

METHODS

SMPD1 was sequenced in 3 cohorts (Israel Ashkenazi Jewish cohort, Montreal/Montpellier, and New York), including 1592 PD patients and 975 controls. Additional data were available for 10,709 Ashkenazi Jewish controls. Acid-sphingomyelinase activity was measured by a mass spectrometry-based assay in the New York cohort. α-Synuclein levels were measured in vitro following CRISPR/Cas9-mediated knockout and siRNA knockdown of SMPD1 in HeLa and BE(2)-M17 cells. Lysosomal localization of acid-sphingomyelinase with different mutations was studied, and in silico analysis of their effect on acid-sphingomyelinase structure was performed.

RESULTS

SMPD1 mutations were associated with PD in the Ashkenazi Jewish cohort, as 1.4% of PD patients carried the p.L302P or p.fsP330 mutation, compared with 0.37% in 10,709 Ashkenazi Jewish controls (OR, 3.7; 95%CI, 1.6-8.2; P = 0.0025). In the Montreal/Montpellier cohort, the p.A487V variant was nominally associated with PD (1.5% versus 0.14%; P = 0.0065, not significant after correction for multiple comparisons). Among PD patients, reduced acid-sphingomyelinase activity was associated with a 3.5- to 5.8-year earlier onset of PD in the lowest quartile versus the highest quartile of acid-sphingomyelinase activity (P = 0.01-0.001). We further demonstrated that SMPD1 knockout and knockdown resulted in increased α-synuclein levels in HeLa and BE(2)-M17 dopaminergic cells and that the p.L302P and p.fsP330 mutations impair the traffic of acid-sphingomyelinase to the lysosome.

CONCLUSIONS

Our results support an association between SMPD1 variants, acid-sphingomyelinase activity, and PD. Furthermore, they suggest that reduced acid-sphingomyelinase activity may lead to α-synuclein accumulation. © 2019 International Parkinson and Movement Disorder Society.

Common and rare GCH1 variants are associated with Parkinson's disease

GCH1 encodes the enzyme guanosine triphospahte (GTP) cyclohydrolase 1, essential for dopamine synthesis in nigrostriatal cells, and rare mutations in GCH1 may lead to Dopa-responsive dystonia (DRD). While GCH1 is implicated in genomewide association studies in Parkinson's disease (PD), only a few studies examined the role of rare GCH1 variants in PD, with conflicting results. In the present study, GCH1 and its 5' and 3' untranslated regions were sequenced in 1113 patients with PD and 1111 controls. To examine the association of rare GCH1 variants with PD, burden analysis was performed. Three rare GCH1 variants, which were previously reported to be pathogenic in DRD, were found in five patients with PD and not in controls (sequence Kernel association test, p = 0.024). A common haplotype, tagged by rs841, was associated with a reduced risk for PD (OR = 0.71, 95% CI = 0.61-0.83, p = 1.24 × 10^-4), and with increased GCH1 expression in brain regions relevant for PD (www.gtexportal.org). Our results support a role for rare, DRD-related variants, and common GCH1 variants in the pathogenesis of PD.

Alpha galactosidase A activity in Parkinson's disease

Glucocerebrosidase (GCase, deficient in Gaucher disease) enzymatic activity measured in dried blood spots of Parkinson's Disease (PD) cases is within healthy range but reduced compared to controls. It is not known whether activities of additional lysosomal enzymes are reduced in dried blood spots in PD. To test whether reduction in lysosomal enzymatic activity in PD is specific to GCase, we measured GCase, acid sphingomyelinase (deficient in Niemann-Pick disease types A and B), alpha galactosidase A (deficient in Fabry), acid alpha-glucosidase (deficient in Pompe) and galactosylceramidase (deficient in Krabbe) enzymatic activities in dried blood spots of PD patients (n = 648) and controls (n = 317) recruited from Columbia University. Full sequencing of glucocerebrosidase (GBA) and the LRRK2 G2019S mutation was performed. Enzymatic activities were compared between PD cases and controls using t-test and regression models adjusted for age, gender, and GBA and LRRK2 G2019S mutation status. Alpha galactosidase A activity was lower in PD cases compared to controls both when only non-carriers were included (excluding all GBA and LRRK2 G2019S carriers and PD cases with age-at-onset below 40) [2.85 μmol/l/h versus 3.12 μmol/l/h, p = 0.018; after controlling for batch effect, p = 0.006 (468 PD cases and 296 controls)], and when including the entire cohort (2.89 μmol/l/h versus 3.10 μmol/l/h, p = 0.040; after controlling for batch effect, p = 0.011). Because the alpha galactosidase A gene is X-linked, we stratified the analyses by sex. Among women who were non-carriers of GBA and LRRK2 G2019S mutations (PD, n = 155; control, n = 194), alpha galactosidase A activity was lower in PD compared to controls (2.77 μmol/l/h versus 3.10 μmol/l/h, p = 0.044; after controlling for a batch effect, p = 0.001). The enzymatic activity of acid sphingomyelinase, acid alpha-glucosidase and galactosylceramidase was not significantly different between PD and controls. In non-carriers, most lysosomal enzyme activities were correlated, with the strongest association in GCase, acid alpha-glucosidase, and alpha galactosidase A (Pearson correlation coefficient between 0.382 and 0.532). In a regression model with all five enzymes among non-carriers (adjusted for sex and age), higher alpha galactosidase A activity was associated with lower odds of PD status (OR = 0.54; 95% CI:0.31-0.95; p = 0.032). When LRRK2 G2019S PD carriers (n = 37) were compared to non-carriers with PD, carriers had higher GCase, acid sphingomyelinase and alpha galactosidase A activity. We conclude that alpha galactosidase A may have a potential independent role in PD, in addition to GCase.

Estimating chronic disease rates in Canada: which population-wide denominator to use?

INTRODUCTION

Chronic disease rates are produced from the Public Health Agency of Canada's Canadian Chronic Disease Surveillance System (CCDSS) using administrative health data from provincial/territorial health ministries. Denominators for these rates are based on estimates of populations derived from health insurance files. However, these data may not be accessible to all researchers. Another source for population size estimates is the Statistics Canada census. The purpose of our study was to calculate the major differences between the CCDSS and Statistics Canada's population denominators and to identify the sources or reasons for the potential differences between these data sources.

METHODS

We compared the 2009 denominators from the CCDSS and Statistics Canada. The CCDSS denominator was adjusted for the growth components (births, deaths, emigration and immigration) from Statistics Canada's census data.

RESULTS

The unadjusted CCDSS denominator was 34 429 804, 3.2% higher than Statistics Canada's estimate of population in 2009. After the CCDSS denominator was adjusted for the growth components, the difference between the two estimates was reduced to 431 323 people, a difference of 1.3%. The CCDSS overestimates the population relative to Statistics Canada overall. The largest difference between the two estimates was from the migrant growth component, while the smallest was from the emigrant component.

CONCLUSION

By using data descriptions by data source, researchers can make decisions about which population to use in their calculations of disease frequency.

A Hermeneutic Phenomenological Examination of the Lived Experience of Incarceration for those with Autism

This study aimed to examine the lived experience of incarceration for those with autism using a hermeneutic phenomenological approach. Eight adults who were incarcerated in New South Wales, Australia, were interviewed. The lived experience of incarceration for the participants was about being in an unpredictable environment characterised by ever-changing routines and complex social situations. Participants were deprived of their ability to create predictability in their environment, and experienced confusion and distress when forced to comply with actions that were in conflict with their logic. Mental health nursing case management is recommended to address the needs of incarcerated persons with autism.

Genetic markers of Restless Legs Syndrome in Parkinson disease

INTRODUCTION

Several studies proposed that Restless Legs Syndrome (RLS) and Parkinson disease (PD) may be clinically and/or etiologically related. To examine this hypothesis, we aimed to determine whether the known RLS genetic markers may be associated with PD risk, as well as with PD subtype.

METHODS

Two case-control cohorts from Tel-Aviv and New-York, including 1133 PD patients and 867 controls were genotyped for four RLS-related SNPs in the genes MEIS1, BTBD9, PTPRD and MAP2K5/SKOR1. The association between genotype, PD risk and phenotype was tested using multivariate regression models.

RESULTS

None of the tested SNPs was significantly associated with PD risk, neither in any individual cohort nor in the combined analysis after correction for multiple comparisons. The MAP2K5/SKOR1 marker rs12593813 was associated with higher frequency of tremor in the Tel-Aviv cohort (61.0% vs. 46.5%, p = 0.001, dominant model). However, the risk allele for tremor in this gene has been associated with reduced RLS risk. Moreover, this association did not replicate in Tremor-dominant PD patients from New-York.

CONCLUSION

RLS genetic risk markers are not associated with increased PD risk or subtype in the current study. Together with previous genetic, neuropathological and epidemiologic studies, our results further strengthen the notion that RLS and PD are likely to be distinct entities.

Stellar dynamics. The fastest unbound star in our Galaxy ejected by a thermonuclear supernova

Hypervelocity stars (HVSs) travel with velocities so high that they exceed the escape velocity of the Galaxy. Several acceleration mechanisms have been discussed. Only one HVS (US 708, HVS 2) is a compact helium star. Here we present a spectroscopic and kinematic analysis of US 708. Traveling with a velocity of ~1200 kilometers per second, it is the fastest unbound star in our Galaxy. In reconstructing its trajectory, the Galactic center becomes very unlikely as an origin, which is hardly consistent with the most favored ejection mechanism for the other HVSs. Furthermore, we detected that US 708 is a fast rotator. According to our binary evolution model, it was spun-up by tidal interaction in a close binary and is likely to be the ejected donor remnant of a thermonuclear supernova.

The nurse academic in the clinical learning setting: An evolving partnership role

Student readiness for practice as a registered nurse can only be achieved through a committed and cooperative partnership between the tertiary and clinical sectors. One important role in the development and maintenance of clinical learning partnerships is that of the nurse academic. As nursing faculties continue to evolve this role it is important that positive initiatives be shared and challenges discussed. With this in mind, the role of the nurse academic in clinical practice introduced at the University of Technology, Sydney (UTS) will be presented. A nurse academic who fulfils this role at UTS is known as an Academic Liaison Person (ALP). This paper begins with a general exploration of the role of the academic in the clinical learning setting and then discusses the associated challenges. The role of the ALP at UTS and its integration with the UTS clinical model for final year students will be presented as a response to these challenges. Through this model the educational expertise of the ALP and the clinical expertise of the practitioner is brought together for the benefit of the nursing student.

The relationship between obsessive-compulsive symptoms and PARKIN genotype: The CORE-PD study

BACKGROUND

Few studies have systematically investigated the association between PARKIN genotype and psychiatric co-morbidities of Parkison's disease (PD). PARKIN-associated PD is characterized by severe nigral dopaminergic neuronal loss, a finding that may have implications for behaviors rooted in dopaminergic circuits such as obsessive-compulsive symptoms (OCS).

METHODS

The Schedule of Compulsions and Obsessions Patient Inventory (SCOPI) was administered to 104 patients with early-onset PD and 257 asymptomatic first-degree relatives. Carriers of one and two PARKIN mutations were compared with noncarriers.

RESULTS

Among patients, carriers scored lower than noncarriers in adjusted models (one-mutation: 13.9 point difference, P = 0.03; two-mutation: 24.1, P = 0.001), where lower scores indicate less OCS. Among asymptomatic relatives, a trend toward the opposite was seen: mutation carriers scored higher than noncarriers (one mutation, P = 0.05; two mutations, P = 0.13).

CONCLUSIONS

First, a significant association was found between PARKIN mutation status and obsessive-compulsive symptom level in both PD and asymptomatic patients, suggesting that OCS might represent an early non-motor dopamine-dependent feature. Second, irrespective of disease status, heterozygotes were significantly different from noncarriers, suggesting that PARKIN heterozygosity may contribute to phenotype. © 2014 International Parkinson and Movement Disorder Society.

Multiple system atrophy and amyotrophic lateral sclerosis in a family with hexanucleotide repeat expansions in C9orf72

IMPORTANCE

Here we report a family with coexistence of multiple system atrophy (MSA) and amyotrophic lateral sclerosis (ALS) with hexanucleotide repeat expansions in C9orf72.

OBSERVATIONS

A 65-year-old woman had a 2-year history of ataxia with autonomic dysfunction but without motor neuron signs. She was diagnosed as having MSA based on her clinical history and the hot cross bun sign on brain magnetic resonance imaging. Her 62-year-old brother had progressive weakness, fasciculations, hyperreflexia, and active denervation on electromyography without cerebellar ataxia. He was diagnosed as having ALS. Both patients had a greater than 1000/2 hexanucleotide expansion in C9orf72.

CONCLUSIONS AND RELEVANCE

Patients with hexanucleotide repeat expansions in C9orf72 can present with MSA as well as ALS or frontotemporal dementia. We report this family with coexisting MSA and ALS, highlighting the phenotypic variability in neurologic presentations with hexanucleotide repeat expansions in C9orf72.

Comparison of Parkinson risk in Ashkenazi Jewish patients with Gaucher disease and GBA heterozygotes

IMPORTANCE

Information on age-specific risk for Parkinson disease (PD) in patients with Gaucher disease (GD) and glucocerebrosidase (GBA) heterozygotes is important for understanding the pathophysiology of the genetic association and for counseling these populations.

OBJECTIVE

To estimate the age-specific risk for PD in Ashkenazi Jewish patients with type 1 GD and in GBA heterozygotes.

DESIGN, SETTING, AND PARTICIPANTS

The study included patients with GD from 2 tertiary centers, Shaare Zedek Medical Center, Jerusalem, Israel (n = 332) and Mount Sinai School of Medicine, New York, New York (n = 95). GBA noncarrier non-PD spouse control participants were recruited at the Center for Parkinson's Disease at Columbia University, New York (n = 77). All participants were Ashekanzi Jewish and most patients (98.1%) with GD carried at least 1 N370S mutation.

MAIN OUTCOMES AND MEASURES

The main outcome measure was a diagnosis of PD. Diagnosis was established in patients with GD on examination. We used a validated family history interview that identifies PD with a sensitivity of 95.5% and specificity of 96.2% to identify PD in family members. Kaplan-Meier survival curves were used to estimate age-specific PD risk among patients with GD (n = 427), among their parents who are obligate GBA mutation carriers (heterozygotes, n = 694), and among noncarriers (parents of non-PD, non-GD control participants, n = 154). The age-specific risk was compared among groups using the log-rank test.

RESULTS

Among those who developed PD, patients with GD had a younger age at onset than GBA heterozygotes (mean, 54.2 vs 65.2 years, respectively; P = .003). Estimated age-specific risk for PD at 60 and 80 years of age was 4.7% and 9.1% among patients with GD, 1.5% and 7.7% among heterozygotes, and 0.7% and 2.1% among noncarriers, respectively. The risk for PD was higher in patients with GD than noncarriers (P = .008, log-rank test) and in heterozygotes than noncarriers (P = .03, log-rank test), but it did not reach statistical significance between patients with GD and GBA heterozygotes (P = .07, log-rank test).

CONCLUSIONS AND RELEVANCE

Patients with GD and GBA heterozygotes have an increased age-specific risk for PD compared with control individuals, with a similar magnitude of PD risk by 80 years of age; however, the number of mutant alleles may play an important role in age at PD onset.