Francisco Escamilla-Sevilla

Bio: Francisco Escamilla-Sevilla is an academic researcher from University of Granada. The author has contributed to research in topics: Parkinson's disease & Deep brain stimulation. The author has an hindex of 13, co-authored 27 publications receiving 955 citations.

Identification of novel risk loci, causal insights, and heritable risk for Parkinson's disease: a meta-analysis of genome-wide association studies

Abstract: Summary Background Genome-wide association studies (GWAS) in Parkinson's disease have increased the scope of biological knowledge about the disease over the past decade. We aimed to use the largest aggregate of GWAS data to identify novel risk loci and gain further insight into the causes of Parkinson's disease. Methods We did a meta-analysis of 17 datasets from Parkinson's disease GWAS available from European ancestry samples to nominate novel loci for disease risk. These datasets incorporated all available data. We then used these data to estimate heritable risk and develop predictive models of this heritability. We also used large gene expression and methylation resources to examine possible functional consequences as well as tissue, cell type, and biological pathway enrichments for the identified risk factors. Additionally, we examined shared genetic risk between Parkinson's disease and other phenotypes of interest via genetic correlations followed by Mendelian randomisation. Findings Between Oct 1, 2017, and Aug 9, 2018, we analysed 7·8 million single nucleotide polymorphisms in 37 688 cases, 18 618 UK Biobank proxy-cases (ie, individuals who do not have Parkinson's disease but have a first degree relative that does), and 1·4 million controls. We identified 90 independent genome-wide significant risk signals across 78 genomic regions, including 38 novel independent risk signals in 37 loci. These 90 variants explained 16–36% of the heritable risk of Parkinson's disease depending on prevalence. Integrating methylation and expression data within a Mendelian randomisation framework identified putatively associated genes at 70 risk signals underlying GWAS loci for follow-up functional studies. Tissue-specific expression enrichment analyses suggested Parkinson's disease loci were heavily brain-enriched, with specific neuronal cell types being implicated from single cell data. We found significant genetic correlations with brain volumes (false discovery rate-adjusted p=0·0035 for intracranial volume, p=0·024 for putamen volume), smoking status (p=0·024), and educational attainment (p=0·038). Mendelian randomisation between cognitive performance and Parkinson's disease risk showed a robust association (p=8·00 × 10−7). Interpretation These data provide the most comprehensive survey of genetic risk within Parkinson's disease to date, to the best of our knowledge, by revealing many additional Parkinson's disease risk loci, providing a biological context for these risk factors, and showing that a considerable genetic component of this disease remains unidentified. These associations derived from European ancestry datasets will need to be followed-up with more diverse data. Funding The National Institute on Aging at the National Institutes of Health (USA), The Michael J Fox Foundation, and The Parkinson's Foundation (see appendix for full list of funding sources).

Carotid body autotransplantation in Parkinson disease: a clinical and positron emission tomography study

Abstract: Background: Carotid body (CB) glomus cells are highly dopaminergic and express the glial cell line derived neurotrophic factor. The intrastriatal grafting of CB cell aggregates exerts neurotrophic actions on nigrostriatal neurons in animal models of Parkinson disease (PD). Objective: We conducted a phase I–II clinical study to assess the feasibility, long term safety, clinical and neurochemical effects of intrastriatal CB autotransplantation in patients with PD. Methods: Thirteen patients with advanced PD underwent bilateral stereotactic implantation of CB cell aggregates into the striatum. They were assessed before surgery and up to 1–3 years after surgery according to CAPIT (Core Assessment Programme for Intracerebral Transplantation) and CAPSIT-PD (Core Assessment Programme for Surgical Interventional Therapies in Parkinson’s Disease) protocols. The primary outcome measure was the change in video blinded Unified Parkinson’s Disease Rating Scale III score in the off-medication state. Seven patients had 18 F-dopa positron emission tomography scans before and 1 year after transplantation. Results: Clinical amelioration in the primary outcome measure was observed in 10 of 12 blindly analysed patients, which was maximal at 6–12 months after transplantation (5–74%). Overall, mean improvement at 6 months was 23%. In the long term (3 years), 3 of 6 patients still maintained improvement (15–48%). None of the patients developed off-period dyskinesias. The main predictive factors for motor improvement were the histological integrity of the CB and a milder disease severity. We observed a non-significant 5% increase in mean putaminal 18 F-dopa uptake but there was an inverse relationship between clinical amelioration and annual decline in putaminal 18 F-dopa uptake (r = −0.829; p = 0.042). Conclusions: CB autotransplantation may induce clinical effects in patients with advanced PD which seem partly related to the biological properties of the implanted glomus cells.

Different patterns of medication change after subthalamic or pallidal stimulation for Parkinson’s disease: target related effect or selection bias?

Abstract: Background: Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) is favoured over bilateral globus pallidus internus (Gpi) DBS for symptomatic treatment of advanced Parkinson's disease (PD) due to the possibility of reducing medication, despite lack of definitive comparative evidence. Objective: To analyse outcomes after one year of bilateral Gpi or STN DBS, with consideration of influence of selection bias on the pattern of postsurgical medication change. Methods: The first patients to undergo bilateral Gpi (n = 10) or STN (n = 10) DBS at our centre were studied. They were assessed presurgically and one year after surgery (CAPIT protocol). Results: Before surgery the Gpi DBS group had more dyskinesias and received lower doses of medication. At one year, mean reduction in UPDRS off medication score was 35% and 39% in the Gpi and STN groups, respectively (non-significant difference). Dyskinesias reduced in proportion to presurgical severity. The levodopa equivalent dose was significantly reduced only in the STN group (24%). This study high-lights the absence of significant differences between the groups in clinical scales and medication dose at one year. In the multivariate analysis of predictive factors for off-state motor improvement, the presurgical levodopa equivalent dose showed a direct relation in the STN and an inverse relation in the Gpi group. Conclusion: Differences in the patterns of medication change after Gpi and STN DBS may be partly due to a patient selection bias. Both procedures may be equally useful for different subgroups of patients with advanced PD, Gpi DBS especially for patients with lower threshold for dyskinesia.

Identification of Candidate Parkinson Disease Genes by Integrating Genome-Wide Association Study, Expression, and Epigenetic Data Sets

Abstract: Importance Substantial genome-wide association study (GWAS) work in Parkinson disease (PD) has led to the discovery of an increasing number of loci shown reliably to be associated with increased risk of disease. Improved understanding of the underlying genes and mechanisms at these loci will be key to understanding the pathogenesis of PD. Objective To investigate what genes and genomic processes underlie the risk of sporadic PD. Design and Setting This genetic association study used the bioinformatic tools Coloc and transcriptome-wide association study (TWAS) to integrate PD case-control GWAS data published in 2017 with expression data (from Braineac, the Genotype-Tissue Expression [GTEx], and CommonMind) and methylation data (derived from UK Parkinson brain samples) to uncover putative gene expression and splicing mechanisms associated with PD GWAS signals. Candidate genes were further characterized using cell-type specificity, weighted gene coexpression networks, and weighted protein-protein interaction networks. Main Outcomes and Measures It was hypothesized a priori that some genes underlying PD loci would alter PD risk through changes to expression, splicing, or methylation. Candidate genes are presented whose change in expression, splicing, or methylation are associated with risk of PD as well as the functional pathways and cell types in which these genes have an important role. Results Gene-level analysis of expression revealed 5 genes (WDR6 [OMIM 606031], CD38 [OMIM 107270], GPNMB [OMIM 604368], RAB29 [OMIM 603949], and TMEM163 [OMIM 618978]) that replicated using both Coloc and TWAS analyses in both the GTEx and Braineac expression data sets. A further 6 genes (ZRANB3 [OMIM 615655], PCGF3 [OMIM 617543], NEK1 [OMIM 604588], NUPL2 [NCBI 11097], GALC [OMIM 606890], and CTSB [OMIM 116810]) showed evidence of disease-associated splicing effects. Cell-type specificity analysis revealed that gene expression was overall more prevalent in glial cell types compared with neurons. The weighted gene coexpression performed on the GTEx data set showed that NUPL2 is a key gene in 3 modules implicated in catabolic processes associated with protein ubiquitination and in the ubiquitin-dependent protein catabolic process in the nucleus accumbens, caudate, and putamen. TMEM163 and ZRANB3 were both important in modules in the frontal cortex and caudate, respectively, indicating regulation of signaling and cell communication. Protein interactor analysis and simulations using random networks demonstrated that the candidate genes interact significantly more with known mendelian PD and parkinsonism proteins than would be expected by chance. Conclusions and Relevance Together, these results suggest that several candidate genes and pathways are associated with the findings observed in PD GWAS studies.

Cognitive effects of subthalamic nucleus stimulation in Parkinson's disease: a controlled study.

Abstract: Background: Subthalamic nucleus deep brain stimulation (STN-DBS) improves motor function in selected patients with Parkinson’s disease (PD) but can be associated with variable changes in cognitive functions. Methods: We studied 21 patients selected for STN-DBS and compared 6-month clinical and neuropsychological outcomes between those who underwent surgery (n = 9) and those who voluntarily refused it (n = 12). Results: Motor and quality of life outcomes were markedly superior in the STN-DBS group versus controls. A wide neuropsychological battery was administered, and the whole sample showed a statistically significant worsening in phonemic verbal fluency, time to perform the Trail Making Test part B, Digit Symbol score of WAIS-III and color-naming score of the Stroop Test. In comparison to controls, a trend to a slightly worse deterioration in phonemic verbal fluency was observed in the STN-DBS patients and was significantly correlated with reductions in the l-dopa-equivalent daily dose (r = 0.850, p = 0.007). Conclusion: Our study confirms the safety of STN-DBS from a cognitive standpoint; a reduction in verbal fluency at 6 months after surgery can also be related to PD progression and medication reduction.

Systematic review of levodopa dose equivalency reporting in Parkinson's disease

Abstract: Interpretation of clinical trials comparing different drug regimens for Parkinson's disease (PD) is complicated by the different dose intensities used: higher doses of levodopa and, possibly, other drugs produce better symptomatic control but more late complications. To address this problem, conversion factors have been calculated for antiparkinsonian drugs that yield a total daily levodopa equivalent dose (LED). LED estimates vary, so we undertook a systematic review of studies reporting LEDs to provide standardized formulae. Electronic database and hand searching of references identified 56 primary reports of LED estimates. Data were extracted and the mean and modal LEDs calculated. This yielded a standardized LED for each drug, providing a useful tool to express dose intensity of different antiparkinsonian drug regimens on a single scale. Using these conversion formulae to report LEDs would improve the consistency of reporting and assist the interpretation of clinical trials comparing different PD medications.

MDS Clinical Diagnostic Criteria for Parkinson's Disease (S19.001)

Abstract: Objective To present the International Parkinson and Movement Disorder Society (MDS) Clinical Diagnostic Criteria for Parkinson9s disease. Background Although several diagnostic criteria for Parkinson9s disease have been proposed, none have been officially adopted by an official Parkinson society. Moreover, the commonest-used criteria, the UK brain bank, were created more than 25 years ago. In recognition of the lack of standard criteria, the MDS initiated a task force to design new diagnostic criteria for clinical Parkinson9s disease. Methods/Results The MDS-PD Criteria are intended for use in clinical research, but may also be used to guide clinical diagnosis. The benchmark is expert clinical diagnosis; the criteria aim to systematize the diagnostic process, to make it reproducible across centers and applicable by clinicians with less expertise. Although motor abnormalities remain central, there is increasing recognition of non-motor manifestations; these are incorporated into both the current criteria and particularly into separate criteria for prodromal PD. Similar to previous criteria, the MDS-PD Criteria retain motor parkinsonism as the core disease feature, defined as bradykinesia plus rest tremor and/or rigidity. Explicit instructions for defining these cardinal features are included. After documentation of parkinsonism, determination of PD as the cause of parkinsonism relies upon three categories of diagnostic features; absolute exclusion criteria (which rule out PD), red flags (which must be counterbalanced by additional supportive criteria to allow diagnosis of PD), and supportive criteria (positive features that increase confidence of PD diagnosis). Two levels of certainty are delineated: Clinically-established PD (maximizing specificity at the expense of reduced sensitivity), and Probable PD (which balances sensitivity and specificity). Conclusion The MDS criteria retain elements proven valuable in previous criteria and omit aspects that are no longer justified, thereby encapsulating diagnosis according to current knowledge. As understanding of PD expands, criteria will need continuous revision to accommodate these advances. Disclosure: Dr. Postuma has received personal compensation for activities with Roche Diagnostics Corporation and Biotie Therapies. Dr. Berg has received research support from Michael J. Fox Foundation, the Bundesministerium fur Bildung und Forschung (BMBF), the German Parkinson Association and Novartis GmbH.

Role of WHO.

Abstract: OVERVIEW The GRA Marketing Internship Program is offered to students who are interested in gaining valuable work experience through efforts in marketing, membership, sales, and events. Interns work directly to assist the Director of Marketing and Communications on various tasks relating to upcoming GRA events. During this internship, students will work a minimum of 10 hours a week and a maximum of 20 hours a week. Students are encouraged to earn credit for their internship, however this is a paid internship. Students interested in obtaining credit for their internship must consult their academic advisor or the intern coordinator at their academic unit.

Peripheral Chemoreceptors: Function and Plasticity of the Carotid Body

Abstract: The discovery of the sensory nature of the carotid body dates back to the beginning of the 20th century. Following these seminal discoveries, research into carotid body mechanisms moved forward progressively through the 20th century, with many descriptions of the ultrastructure of the organ and stimulus-response measurements at the level of the whole organ. The later part of 20th century witnessed the first descriptions of the cellular responses and electrophysiology of isolated and cultured type I and type II cells, and there now exist a number of testable hypotheses of chemotransduction. The goal of this article is to provide a comprehensive review of current concepts on sensory transduction and transmission of the hypoxic stimulus at the carotid body with an emphasis on integrating cellular mechanisms with the whole organ responses and highlighting the gaps or discrepancies in our knowledge. It is increasingly evident that in addition to hypoxia, the carotid body responds to a wide variety of blood-borne stimuli, including reduced glucose and immune-related cytokines and we therefore also consider the evidence for a polymodal function of the carotid body and its implications. It is clear that the sensory function of the carotid body exhibits considerable plasticity in response to the chronic perturbations in environmental O2 that is associated with many physiological and pathological conditions. The mechanisms and consequences of carotid body plasticity in health and disease are discussed in the final sections of this article.

The genetic architecture of the human cerebral cortex

Abstract: The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder.