The classic rodent model of Parkinson’s disease (PD) is produced by unilateral lesioning of pars compacta substantia nigra (SNpc) in adult rats, producing unilateral motor deficits which can be assessed by dopamine (DA) D2 receptor (D2-R) agonist induction of measurable unilateral rotations. Bilateral SNpc lesions in adult rats produce life-threatening aphagia, adipsia, and severe motor disability resembling paralysis-a PD model that is so compromised that it is seldom used. Described in this paper is a PD rodent model in which there is bilateral 99% loss of striatal dopaminergic innervation, produced by bilateral intracerebroventricular or intracisternal 6-hydroxydopamine (6-OHDA) administration to perinatal rats. This procedure produces no lethality and does not shorten the life span, while rat pups continue to suckle through the pre-weaning period; and eat without impairment post-weaning. There is no obvious motor deficit during or after weaning, except with special testing, so that parkinsonian rats are indistin-guishable from control and thus allow for behavioral assessments to be conducted in a blinded manner. L-DOPA (L-3,4-dihydroxyphenylalanine) treatment increases DA content in striatal tissue, also evokes a rise in extraneuronal (i.e.,in vivo microdialysate) DA, and is able to evoke dyskinesias. D2-R agonists produce effects similar to those of L-DOPA. In addition, effects of both D1-and D2-R agonist effects on overt or latent receptor supersensitization are amenable to study. Elevated basal levels of reactive oxygen species (ROS), namely hydroxyl radical, occurring in dopaminergic denervated striatum are suppressed by L-DOPA treatment. Striatal serotoninergic hyperinnervation ensuing after perinatal dopaminergic denervation does not appear to interfere with assessments of the dopaminergic system by L-DOPA or D1-or D2-R agonist challenge. Partial lesioning of serotonin fibers with a selective neurotoxin either at birth or in adulthood is able to eliminate sero-toninergic hyperinnervation and restore the normal level of serotoninergic innervation. Of all the animal models of PD, that produced by perinatal 6-OHDA lesioning provides the most pronounced destruction of nigrostriatal neurons, thus representing a model of severe PD, as the neurochemical outcome resembles the status of severe PD in humans but without obvious motor deficits.

The molecular mechanism responsible for degenerative process in the nigrostriatal dopaminergic system in Parkinson’s disease (PD) remains unknown. One major advance in this field has been the discovery of several genes associated to familial PD, including alpha synuclein, parkin, LRRK2, etc., thereby providing important insight toward basic research approaches. There is an consensus in neurodegenerative research that mitochondria dysfunction, protein degradation dysfunction, aggregation of alpha synuclein to neurotoxic oligomers, oxidative and endoplasmic reticulum stress, and neuroinflammation are involved in degeneration of the neuromelanin-containing dopaminergic neurons that are lost in the disease. An update of the mechanisms relating to neurotoxins that are used to produce preclinical models of Parkinson´s disease is presented. 6-Hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and rotenone have been the most wisely used neurotoxins to delve into mechanisms involved in the loss of dopaminergic neurons containing neuromelanin. Neurotoxins generated from dopamine oxidation during neuromelanin formation are likewise reviewed, as this pathway replicates neurotoxin-induced cellular oxidative stress, inactivation of key proteins related to mitochondria and protein degradation dysfunction, and formation of neurotoxic aggregates of alpha synuclein. This survey of neurotoxin modeling—highlighting newer technologies and implicating a variety of processes and pathways related to mechanisms attending PD—is focused on research studies from 2012 to 2014.

The cyanobacterial toxin β-N-methylamino-l-alanine (BMAA) now appears to be a cause of Guamanian amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC). Its production by cyanobacteria throughout the world combined with multiple mechanisms of BMAA neurotoxicity, particularly to vulnerable subpopulations of motor neurons, has significantly increased interest in investigating exposure to this non-protein amino acid as a possible risk factor for other forms of neurodegenerative illness. We here provide a brief overview of BMAA studies and provide an introduction to this collection of scientific manuscripts in this special issue on BMAA.

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by alpha-synuclein accumulation and loss of dopaminergic neurons in the substantia nigra (SN) region of the brain. Increased levels of alpha-synuclein have been shown to result in loss of mitochondrial electron transport chain complex I activity leading to increased reactive oxygen species (ROS) production. WT alpha-synuclein was stably overexpressed in human BE(2)-M17 neuroblastoma cells resulting in increased levels of an alpha-synuclein multimer, but no increase in alpha-synuclein monomer levels. Oxygen consumption was decreased by alpha-synuclein overexpression, but ATP levels did not decrease and ROS levels did not increase. Treatment with ferrous sulfate, a ROS generator, resulted in decreased oxygen consumption in both control and alpha-synuclein overexpressing cells. However, this treatment only decreased ATP levels and increased ROS production in the cells overexpressing alpha-synuclein. Similarly, paraquat, another ROS generator, decreased ATP levels in the alpha-synuclein overexpressing cells, but not in the control cells, further demonstrating how alpha-synuclein sensitized the cells to oxidative insult. Proteomic analysis yielded molecular insights into the cellular adaptations to alpha-synuclein overexpression, such as the increased abundance of many mitochondrial proteins. Many amino acids and citric acid cycle intermediates and their ester forms were individually supplemented to the cells with l-serine, l-proline, l-aspartate, or l-glutamine decreasing ROS production in oxidatively stressed alpha-synuclein overexpressing cells, while diethyl oxaloacetate or l-valine supplementation increased ATP levels. These results suggest that dietary supplementation with individual metabolites could yield bioenergetic improvements in PD patients to delay loss of dopaminergic neurons.

Abstract Parkinson’s disease and Huntington’s disease are progressive neurodegenerative movement disorders that typically manifest in adulthood. In this study, genetic risk factors contributing to these two movement disorders were investigated in Finnish patients. Patients with early-onset or late-onset Parkinson’s disease as well as population controls were examined. The p.L444P mutation in GBA was found to contribute to the risk of Parkinson’s disease. POLG1 compound heterozygous mutations were detected in two patients with Parkinson’s disease and rare length variants in POLG1 were associated with Parkinson’s disease. Variants in SMPD1, LRRK2 or CHCHD10, previously detected in other populations, were not detected, suggesting that they are rare or even absent in the Finnish population. Patients with Huntington’s disease were investigated for HTT gene haplotypes as well as whether these haplotypes alter the stability of the elongated CAG repeat. Haplogroup A was less common in Finns than in other European populations, whereas it was significantly more common in patients with Huntington’s disease than in the general population. Certain HTT haplotypes as well as the parental gender were found to affect the repeat instability. We found that compound heterozygous mutations in POLG1 were causative of Parkinson’s disease, rare length variants in POLG1 were associated with Parkinson’s disease and GBA p.L444P was significantly more frequent in patients than in the controls, which suggests that these mutations are associated with the development of Parkinson’s disease. The low prevalence of Huntington’s disease in Finland correlates with the low frequency of the disease-associated HTT haplogroup A. Paternal inheritance combined with haplotype A1 increased the risk of repeat expansion. Movement disorders in Finland were found to share some of the same genetic risk factors found in other European populations, but some other recognized genetic variants could not be detected. / Tiivistelmä Parkinsonin tauti ja Huntingtonin tauti ovat hermostoa rappeuttavia eteneviä liikehäiriösairauksia, jotka tyypillisesti ilmenevät aikuisiällä. Tässä tutkimuksessa selvitettiin näiden kahden liikehäiriösairauden geneettisiä riskitekijöitä suomalaisilla potilailla. Tutkimme potilaita, joilla oli varhain alkava Parkinsonin tauti tai myöhään alkava Parkinsonin tauti sekä väestökontrolleja. GBA-geenin p.L444P mutaation havaittiin lisäävän Parkinsonin taudin riskiä. Kaksi Parkinsonin tautia sairastavaa potilasta oli yhdistelmäheterotsygootteja haitallisten POLG1-geenin varianttien suhteen ja harvinaiset POLG1 CAG toistojaksovariantit assosioituivat Parkinsonin tautiin. Tutkittuja variantteja SMPD1-, LRRK2- ja CHCHD10-geeneissä ei löydetty tästä aineistosta lainkaan, mikä viittaa siihen, että ne puuttuvat suomalaisesta väestöstä tai ovat harvinaisia. Huntingtonin tautia sairastavilta potilailta tutkittiin HTT-geenin haploryhmiä ja niiden vaikutusta Huntingtonin tautia aiheuttavan pidentyneen toistojakson epästabiiliuteen. Haploryhmä A oli suomalaisessa väestössä harvinainen verrattuna eurooppalaiseen väestöön ja se oli huomattavasti yleisempi Huntingtonin tautipotilailla kuin väestössä. Toistojakson epästabiiliuteen vaikuttivat tietyt HTT-geenin haplotyypit samoin kuin sen vanhemman sukupuoli, jolta pidentynyt toistojakso periytyy. POLG1 yhdistelmäheterotsygoottien katsottiin aiheuttavat Parkinsonin tautia ja harvinaisten POLG1 CAG toistojaksovarianttien todettiin assosioituvan Parkinsonin tautiin Suomessa. GBA p.L444P mutaatio merkittävästi yleisempi Parkinsonin tautipotilailla kuin kontrolleilla, mikä viittaa siihen, että se on Parkinsonin taudin riskitekijä. Huntingtonin tautiin assosioituvan haploryhmä A:n matala frekvenssi selittää taudin vähäistä esiintyvyyttä Suomessa. Paternaalinen periytyminen ja haplotyyppi A1 lisäsivät HTT-geenin toistojakson pidentymisen riskiä. Liikehäiriösairauksilla todettiin Suomessa osittain samanlaisia riskitekijöitä kuin muualla Euroopassa, mutta kaikkia tutkittuja variantteja emme havainneet.

En la presente Tesis Doctoral se describen los cambios celulares que ocurren en la retina en la enfermedad de Parkinson y su posible uso como biomarcadores tempranos de la enfermedad. Los pacientes con enfermedad de Parkinson poseen acumulaciones de alfa sinucleína fosforilada en la retina similares a las que se encuentran en el cerebro de los mismos pacientes. De hecho, la cantidad de alfa-sinucleína fosforilada en la retina correlaciona con la cantidad de alfa-sinucleína fosforilada en el cerebro, con el estadio de progresión de la enfermedad y con la severidad de los síntomas motores. Además, en la retina de enfermos de párkinson se describe una degeneración de las células ganglionares melanopsínicas de la retina, lo que podría explicar las alteraciones en los ritmos circadianos y los desórdenes del sueño que aparecen en pacientes. Finalmente, también se muestra la degeneración de las células amacrinas dopaminérgicas, que se reducen en un 45%. Este fallo en el sistema dopaminérgico de la retina provoca alteraciones morfológicas en las células amacrinas AII, sus principales postsinápticas, y podría explicar algunas alteraciones visuales descritas en la enfermedad como la disminución de la sensibilidad al contraste o de la agudeza visual. En global, los resultados muestran que la retina reproduce los procesos degenerativos que ocurren en el cerebro en la enfermedad de Parkinson y, por tanto, que es un tejido idóneo para el estudio de la enfermedad. Además, el estudio de la retina aporta información sobre el estadio de la enfermedad y puede ser empleado como un biomarcador temprano que ayude al diagnóstico y seguimiento de la misma.

Gångproblematiken hos personer med Parkinsons sjukdom är svårhanterad av både vårdtagare och vårdare och kräver mycket kunskap och förståelse. Syftet med denna litteraturstudie var att identifiera omvårdnadsåtgärder som kan underlätta gångproblematik hos personer med Parkinsons sjukdom. Tio kvantitativa studier har används i denna litteraturstudie och sökningar har gjorts i Pubmed och i CINAHL. Resultatet från dessa sökningar presenterades i fyra strategier och fynden var rehabilitering, individanpassad träning, stimuli och användandet av dagböcker. Dessa strategier kan användas som verktyg för en sjuksköterska när hon interagerar med personer med Parkinsons sjukdom. Genom en ökad insikt i hur det går att underlätta den specifika gångproblematiken kan omvårdnaden optimeras. / Gait disturbance in persons with Parkinson’s disease is difficult to manage by both caretakers and caregivers and it requires much knowledge and understanding. The aim of this literature review was to identify means to aid the gait disturbance in persons with Parkinson’s disease. Ten quantitative studies have been used in this literature review and searches were carried out in Pubmed and CINAHL. The results from these searches were presented in four strategies and the findings were rehabilitation, individual exercise schedules, cueing and the use of diaries. These strategies can be used by a nurse as tools while she is interacting with persons with Parkinson’s disease. With a greater insight on the specific gait disturbances nursing can be optimized.

Parkinson’s disease (PD) is frequently compounded by neruropsychiatric complications, increasing disability. The combined effect of motor and mental status on care-dependency in PD outpatients is not well characterized. We conducted a cross-sectional study of 1449 PD outpatients. The assessment comprised the Montgomery–Asberg Depression Rating Scale (MADRS) and the diagnostic criteria for dementia. PD severity and treatment complications were rated using Hoehn and Yahr staging and the Unified Parkinson’s Disease Rating Scale (UPDRS) IV. The acknowledged level of care-dependency was documented. Care-dependency was present in 18.3% of all patients. A total of 13.9% had dementia, 18.8% had depression, and 14.3% had both. Regression analyses revealed increasing effects of age, PD duration, and PD severity on care-dependency in all three mental-disorder subgroups with the strongest effects in patients with depression only. Depressed patients with antidepressive treatment still had significantly higher PD severity, higher MADRS and UPDRS-IV scores but were not more likely to be care-dependent than non-depressed patients. Older age, longer duration and increased severity of PD contribute to care-dependency in patients with untreated depression. Treatment of depression is associated with lower rates of care-dependency.

The neurotoxin 6-hydroxydopamine (6-OHDA), following pretreatment with the norepinephrine transport inhibitor desipramine, selectively destroys dopaminergic neurons. When given to rats, neonatal 6-OHDA (n6-OHDA) crosses the blood-brain barrier to destroy 90-99% of dopaminergic nerves in pars compacta substantia nigra (SNpc). The n6-OHDA-lesioned rat is posed as a reasonable animal model for PD: (a) the magnitude of dopaminergic neuronal destruction is expansive, (b) mapping of dopaminergic denervation has been defined, (c) effects on dopamine (DA) receptor alterations have been elucidated (d) as well as changes in receptor sensitivity status, (e) reactive sprouting of serotoninergic innervation (i.e. hyperinnervation) has been mapped, and (f) interplay between serotoninergic and dopaminergic systems is characterized. (g) A broad range of locomotor and stereotyped behaviors has been assessed and (h) large numbers of neurochemical assessments have been attained. (i) n6-OHDA-lesioned rats survive 6-OHDA lesioning and (j) the rat is behaviorally indistinguishable from controls. Dopaminergic destruction in early ontogeny rather in adulthood is a 'treatment liability' of this model, yet other animal models have liability issues of a serious nature-the initial one being use of a neurotoxin to produce the animal model of PD. The n6-OHDA-lesioned rat is proposed as a PD model for its value in associating the SNpc dopaminergic lesion with behavioral outcomes, also for replicability of dopaminergic destruction, and the accompanying neuronal adaptations and interplay between neuronal phenotypes in brain-which provide a means to better define and understand the range of deficits and neuronal adaptations that are likely to occur in human PD.

Yes / This study introduces a quantum-inspired computational paradigm to address the unresolved problem of Convolutional Neural Networks (CNNs) using the Rectified Linear Unit (ReLU) activation function (AF), i.e., the ‘dying ReLU’. This problem impacts the accuracy and the reliability in image classification tasks for critical applications, such as in healthcare. The proposed approach builds on the classical ReLU and Leaky ReLU, applying the quantum principles of entanglement and superposition at a computational level to derive two novel AFs, respectively the ‘Quantum ReLU’ (QReLU) and the ‘modified-QReLU’ (m-QReLU). The proposed AFs were validated when coupled with a CNN using seven image datasets on classification tasks involving the detection of COVID-19 and Parkinson’s Disease (PD). The out-of-sample/test classification accuracy and reliability (precision, recall and F1-score) of the CNN were compared against those of the same classifier when using nine classical AFs, including ReLU-based variations. Findings indicate higher accuracy and reliability for the CNN when using either QReLU or m-QReLU on five of the seven datasets evaluated. Whilst retaining the best classification accuracy and reliability for handwritten digits recognition on the MNIST dataset (ACC = 99%, F1-score = 99%), avoiding the ‘dying ReLU’ problem via the proposed quantum AFs improved recognition of PD-related patterns from spiral drawings with the QReLU especially, which achieved the highest classification accuracy and reliability (ACC = 92%, F1-score = 93%). Therefore, with these increased accuracy and reliability, QReLU and m-QReLU can aid critical image classification tasks, such as diagnoses of COVID-19 and PD. / The authors declare that this was the result of a HEIF 2020 University of Bradford COVID-19 response-funded project ‘Quantum ReLU-based COVID-19 Detector: A Quantum Activation Function for Deep Learning to Improve Diagnostics and Prognostics of COVID-19 from Non-ionising Medical Imaging’. However, the funding source was not involved in conducting the study and/or preparing the article.