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Association of vitamin D receptor gene polymorphisms and Parkinson's disease in Hungarians

Vitamin D receptor (VDR) gene encodes a transcription factor that influences calcium homeostasis and immunoregulation, and may play a role in neurological disorders including Parkinsons disease (PD). The investigations of the association between VDR and PD in different populations revealed various results. In a present study 100 PD patients and 109 healthy controls from the Hungarian population were genotyped for four polymorphic sites (BsmI, ApaI, FokI and TaqI) in the VDR gene. The polymorphisms were determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Our results demonstrate an association between the FokI C allele and PD; the frequency of the C allele was significantly higher in PD patients than in controls, suggesting that this polymorphism may have a role in the development of PD in these patients.

Brain Aging and Disorders of the Central Nervous System: Kynurenines and Drug Metabolism

INTRODUCTION The kynurenine pathway includes several neuroactive compounds, including kynurenic acid, picolinic acid, 3-hydroxykynurenine and quinolinic acid. The enzymatic cascade of the kynurenine pathway is tightly connected with the immune system, and may provide a link between the immune system and neurotransmission. Main Areas Covered: Alterations in this cascade are associated with neurodegenerative, neurocognitive, autoimmune and psychiatric disorders, such as Parkinsons disease, Huntingtons disease, Alzheimers disease, multiple sclerosis, amyotrophic lateral sclerosis, migraine or schizophrenia. HIGHLIGHTS This review highlights the alterations in this metabolic pathway in the physiological aging process and in different disorders. A survey is also presented of therapeutic possibilities of influencing this metabolic route, which can be achieved through the use of synthetic kynurenic acid analogues, enzyme inhibitors or even nanotechnology.

An assessment of the frequency of mutations in the GBA and VPS35 genes in Hungarian patients with sporadic Parkinson's disease.

Parkinsons disease (PD) is the second most common neurodegenerative disorder, with cases of either familial or sporadic origin. Several polymorphisms in a number of genes have been proved to have an important role in the development of PD. Particular attention has recently been paid to genes of the glucocerebrosidase (GBA) and the vacuolar protein sorting-associated protein 35 (VPS35). In this study, the three most common mutations (L444P, N370S and R120W) of the GBA gene and the D620N mutation of the VPS35 gene were examined in 124 Hungarian patients diagnosed with sporadic PD (SPD) and 122 control subjects. The frequency of the L444P mutation of the GBA gene proved to be higher in the PD patients (2.4%) than in the controls (0%), although the difference was not statistically significant. All the patients who carried the mutant allele were in the early-onset PD (EOPD) group. However, neither the R120W nor the N370S variant of the GBA gene nor D620N mutation of the VPS35 gene were detected among the PD cases or the controls. Even though these results suggest that the studied mutations are quite rare in SPD patients, the most frequent L444P mutation of the GBA gene may be associated with the development of EOPD in the Hungarian population.

Memantine and kynurenic acid: Current neuropharmacological aspects

Glutamatergic neurotransmission, of special importance in the human brain, is implicated in key brain functions such as synaptic plasticity and memory. The excessive activation of N-methyl- D-aspartate (NMDA) receptors may result in excitotoxic neuronal damage; this process has been implicated in the pathomechanism of different neurodegenerative disorders, such as Alzheimer’s disease (AD). Memantine is an uncompetitive antagonist of NMDA receptors with a favorable pharmacokinetic profile, and is therefore clinically well tolerated. Memantine is approved for the treatment of AD, but may additionally be beneficial for other dementia forms and pain conditions. Kynurenic acid (KYNA) is an endogenous antagonist of NMDA receptors which has been demonstrated under experimental conditions to be neuroprotective. The development of a well-tolerated NMDA antagonist may offer a novel therapeutic option for the treatment of neurodegenerative disease and pain syndromes. KYNA may be a valuable candidate for future drug development.

The Genetic Link between Parkinson's Disease and the Kynurenine Pathway Is Still Missing.

Background. There is substantial evidence that the kynurenine pathway (KP) plays a role in the normal physiology of the brain and is involved in the pathology of neurodegenerative disorders such as Huntingtons disease and Parkinsons disease (PD). Objective. We set out to investigate the potential roles in PD of single nucleotide polymorphisms (SNPs) from one of the key enzymes of the KP, kynurenine 3-monooxygenase (KMO). Methods. 105 unrelated, clinically definitive PD patients and 131 healthy controls were enrolled to investigate the possible effects of the different alleles of KMO. Fluorescently labeled TaqMan probes were used for allele discrimination. Results. None of the four investigated SNPs proved to be associated with PD or influenced the age at onset of the disease. Conclusions. The genetic link between the KP and PD is still missing. The investigated SNPs presumably do not appear to influence the function of KMO and probably do not contain binding sites for regulatory proteins of relevance in PD. This is the first study to assess the genetic background behind the biochemical alterations of the kynurenine pathway in PD, directing the attention to this previously unexamined field.

High‐throughput sequencing revealed a novel SETX mutation in a Hungarian patient with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the degeneration of the motor neurons. To date, 126 genes have been implicated in ALS. Therefore, the heterogenous genetic background of ALS requires comprehensive genetic investigative approaches.

Investigation of vitamin D receptor polymorphisms in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) patients manifest aberrations in the vitamin D endocrine system, with a vitamin D deficiency. Genetic investigations have identified those proteins which link vitamin D to ALS pathology: major histocompatibility complex class II molecules, toll‐like receptors, poly(ADP ribose) polymerase‐1, haeme oxygenase‐1, the reduced form of nicotinamide adenine dinucleotide phosphate and calcium‐binding proteins. Vitamin D additionally impacts ALS through cell‐signalling mechanisms: glutamate, matrix metalloproteinases, the Wnt/β‐catenin signalling pathway, mitogen‐activated protein kinase pathways, prostaglandins, reactive oxygen species and nitric oxide synthase, but its role has been only poorly investigated.

Rapid genotyping of genetically modified laboratory animals from whole blood samples without DNA preparation

A new, rapid method is described which permits the genotyping of genetically modified animals from a microlitre volume of whole blood samples via one step polymerase chain reaction amplification. The major advantage of the presented method is the exclusion of a DNA preparation step, which significantly reduces the time expenditure and work load of the genetic testing. Pilot studies indicate, that this method is efficient and applicable also on tissue biopsies and larger amount of blood providing a rapid and reliable new technique over conventional genotyping approaches.

Investigational α-synuclein aggregation inhibitors: hope for Parkinson’s disease

ABSTRACT Introduction: The therapeutic management of Parkinson’s disease (PD) is challenging and has not been fully resolved. The main challenges include motor fluctuations and levodopa-induced dyskinesia. Moreover, no disease-modifying or neuroprotective therapy is currently available. Areas covered: This review focuses on α-synuclein aggregation inhibitors and their therapeutic role in PD, with special attention to heat shock proteins, immunotherapy (active and passive), the potential of targeting the Ser129 phosphorylation site, and the antibiotic possibilities. Expert opinion: The induction of chaperones may provide beneficial strategy to target synucleinopathies, but further investigations are needed to find the best options. The promising preclinical results with immunotherapy suggest that it may be a valuable disease-modifying therapy in PD in the future. Clinical trials are currently in the initial phases, and future studies need to confirm the beneficial therapeutic effect in humans and clarify open questions as regards the exact mode of action and potential safety concerns. In case of covalent modifications, phosphorylation of α-synuclein is of outstanding importance; however, conflicting results and open questions exist which necessitate clarification. In vitro results suggest that several antibiotics may also influence α-synuclein aggregation, but these results are to be confirmed in the future.

Promising therapeutic agents for the treatment of Parkinson’s disease

ABSTRACT Introduction: The therapeutic management of Parkinson’s disease has not yet been fully resolved, with motor fluctuations and levodopa-induced dyskinesia representing special therapeutic challenges. Furthermore, no disease-modifying therapies are currently available. Areas covered: This review focuses on promising novel therapies that are at present under investigation in Phase I or Phase II trials. Special emphasis is placed on gene therapies: vectors, the utilized gene constructs and the side-effects. Moreover, the main risk factors of the gene therapy (the insertional mutagenesis, the uncontrolled overproduction of the expressed protein and the autoimmune and inflammatory responses) are described. Expert opinion: Gene therapies represent a promising field in the therapeutic palette. In order to mitigate the side-effects of this therapy, the developments focus on the vectors applied. Gene therapy appears to be promising candidate for the management of motor complications in advanced stages of Parkinson’s disease. In addition to dopamine replacement therapy, this field may also offer a solution for neurogenesis and neuroprotection.