Yu-Yan Tan

Methylation of α-synuclein and leucine-rich repeat kinase 2 in leukocyte DNA of Parkinson's disease patients.

BACKGROUND Recent studies highlight the role of DNA methylation in the pathogenesis of Parkinsons disease (PD). However, there is a paucity of studies exploring the role of blood-based DNA methylation in PD. We aimed to explore identifiable epigenetic biomarkers for PD by analyzing the methylation status of α-synuclein (SNCA) and leucine-rich repeat kinase 2 (LRRK2) in leukocytes. METHODS Bisulfite Specific PCR-based Sequencing method was used for semi-quantitative detection of methylation status of CpG islands in SNCA and LRRK2 promoter regions. Bisulfite Specific Cloning-based Sequencing method was used for further quantitative examination of CpG-2 methylation of SNCA. mRNA level was also detected in leukocytes. RESULTS Semi-quantitative detection showed that the methylation status of SNCA CpG-2 differed between PD patients and normal controls, while there was no difference in CpG-1 of SNCA or in LRRK2 promoter. Further quantitative analysis by clonal assay showed that the CpG-2 of SNCA was hypomethylated in PD patients compared with the normal control (5.90% versus 7.69%, P=0.034). Moreover, among the 14 CpG sites of CpG-2, the 2nd, 4th and 9th CpG sites were significantly hypomethylated in PD patients. In subgroups of PD, the methylation level decreased in the early-onset PD patients (P=0.001). RT-PCR examination showed that SNCA mRNA was increased in PD patients compared with normal control (P=0.003). CONCLUSIONS Our results indicated that the methylation level of SNCA CpG-2, especially that of the 2nd, 4th and 9th CpG sites in leukocytes might have great potential to be a useful and informative biomarker in PD diagnosis and treatment.

Amyloid-beta1-42 induces reactive oxygen species-mediated autophagic cell death in U87 and SH-SY5Y cells.

Alzheimers disease (AD) is a neurodegenerative disorder initiated by the aggregation of amyloid-beta peptide (Abeta). Macroautophagy, which is essential for cell survival as well as the promotion of cell death, has been observed extensively in AD brains or transgenic mice overexpressing Abeta protein precursor. However, the role of macroautophagy in the pathogenesis of AD is unclear. In this study, we showed that Abeta1-42 triggered autophagic cell death in both human glioma cell line (U87 cell) and human neuroblastoma cell line (SH-SY5Y cell). Abeta1-42-induced cytotoxicity and autophagic cell death were blocked by the autophagy inhibitor 3-methyladenine (3-MA) or by small interfering RNA against the autophagy gene Beclin-1. Reactive oxygen species (ROS) accumulation was also detected in both Abeta1-42 treated cell lines and this accumulation was not affected by 3-MA. Moreover, pretreatment with the ROS scavenger N-acetylcysteine inhibited ROS accumulation and autophagic cell death induced by Abeta1-42, suggesting that Abeta1-42-induced ROS accumulation might trigger the onset of autophagy and subsequent autophagic cell death. These findings provide further insights into the mechanisms underlying Abeta-induced cytotoxicity.

Economic burden of Parkinson's disease in a developing country: A retrospective cost analysis in Shanghai, China

We investigated economic costs from patients with Parkinsons disease (PD) in Shanghai, China, which could be used as a baseline for future evaluations. Data were collected from 190 patients by interview during 1‐year period. Direct medical care costs averaged approximately Chinese yuan, renminbi (RMB) 4,305 (USD 519, or EUR 410) per year per patient, of which drugs (RMB 2,677) accounted for the major costly component. Nonmedical direct costs were much less than direct health care costs, averaging approximately RMB 3,301 (USD 398, or EUR 314). Costs due to loss of productivity averaged approximately RMB 73 (USD 8.8, or EUR 7.0) per patient per year. Taken together, the overall mean annual cost for PD in our series was approximately RMB 7,679 (USD 925, or EUR 731), and these costs accounted for around half of the mean annual income. Total cost was significantly associated with the disease severity and the frequency of outpatient visits. In addition, levodopa equivalent dose (LED) and the number of drugs being taken were also closely related with the drug cost. The results indicate that the economic burden of Chinese PD patients is heavy.

Neuroprotective effects of PACAP27 in mice model of Parkinson’s disease involved in the modulation of KATP subunits and D2 receptors in the striatum

Pituitary adenylate cyclase activating polypeptide (PACAP) exhibits a protective effect against neural injury in vitro and in vivo. However, it has not been reported whether peripheral intravenous administration of PACAP could confer benefits in animal models of Parkinsons disease (PD). Furthermore, the underlying molecular mechanisms responsible for these effects are poorly understood. In the present experiments, we determined the effects and mechanism of action of intravenously administered PACAP27 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Our results indicate that intravenous injection of PACAP27 offers neuroprotective effects in the MPTP-induced PD mouse model which may not be directly associated with the expression levels of the monoamine transporters. However, this effect may be correlated with its ability to selectively regulate not only K(ATP) subunits, but D2 receptors in the striatum. Our findings suggest that the benefit of PACAP may accompany with changes not only in dopaminergic neurotransmission, but also in cholinergic neurotransmission that are relatively associated with the K(ATP) subunits and D2 receptors in the striatum.

Curcumin inhibition of JNKs prevents dopaminergic neuronal loss in a mouse model of Parkinson's disease through suppressing mitochondria dysfunction

Curcumin,a natural polyphenol obtained from turmeric,has been implicated to be neuroprotective in a variety of neurodegenerative disorders although the mechanism remains poorly understood. The results of our recent experiments indicated that curcumin could protect dopaminergic neurons from apoptosis in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease (PD). The death of dopaminergic neurons and the loss of dopaminergic axon in the striatum were significantly suppressed by curcumin in MPTP mouse model. Further studies showed that curcumin inhibited JNKs hyperphosphorylation induced by MPTP treatment. JNKs phosphorylation can cause translocation of Bax to mitochondria and the release of cytochrome c which both ultimately contribute to mitochondria-mediated apoptosis. These pro-apoptosis effect can be diminished by curcumin. Our experiments demonstrated that curcumin can prevent nigrostriatal degeneration by inhibiting the dysfunction of mitochondrial through suppressing hyperphosphorylation of JNKs induced by MPTP. Our results suggested that JNKs/mitochondria pathway may be a novel target in the treatment of PD patients.

Analysis of genome ‐ wide association study ‐ linked loci in Parkinson's disease of Mainland China

Genome‐wide association studies (GWAS) have identified numerous single‐nucleotide polymorphisms (SNPs) that can modulate the risk of developing Parkinsons disease (PD).

Endoplasmic reticulum stress contributes to the cell death induced by UCH-L1 inhibitor

At the neuropathological level, Parkinson’s disease (PD) is characterized by the accumulation of misfolded proteins, which can trigger the unfolded protein response (UPR). UCH-L1 is a component of ubiquitin proteasome system (UPS). It is reported that the loss of its function will impair ubiquitin proteasome system and cause toxicity to cells. But its mechanism has not been illustrated. In this study, we detected the protein expression of Bip/Grp78 and the spliced form of XBP-1 to examine the activation of unfolded protein response after SK-N-SH cells being treated with LDN-57444, a UCH-L1 inhibitor which could inhibit UCH-L1 hydrolase activity. Our data showed that UCH-L1 inhibitor was able to cause cell death through the apoptosis pathway by decreasing the activity of ubiquitin proteasome system and increasing the levels of highly ubiquitinated proteins, both of which can activate unfolded protein response. There is a lot of evidence that unfolded protein response is activated as a protective response at the early stage of the stress; this protective response can switch to a pro-apoptotic response when the stress persists. In this study, we demonstrated this switch by detecting the upregulation of CHOP/Gadd153. Taken together, our data indicated that the apoptosis induced by UCH-L1 inhibitor may be triggered by the activation of endoplasmic reticulum stress (ERS). Moreover, we provide a new cell model for studying the roles of UCH-L1 in Parkinson’s disease.

Sleep disorders in Chinese patients with Parkinson's disease: validation study of a Chinese version of Parkinson's disease sleep scale

To evaluate the Chinese version of the Parkinsons disease sleep scale (PDSS) as an instrument for measuring sleep disorders in Chinese patients with Parkinsons disease (PD). The objective of the present study was to carry out a metric analysis of a Chinese version of PDSS using a cross-sectional study of 126 patients with PD who participated in the study. Usual measures for PD patients including the Pittsburgh sleep quality index (PSQI), the Epworth sleepiness scale (ESS), the Geriatric Depression Scale (GDS), and the Hamilton Anxiety Scale (HAMA) were applied by neurologists. The intra-class correlation coefficient was 0.880, and test-retest reliability for total PDSS score was 0.914. The Mean total PDSS score was 118.38+/-26.07. There was a significant correlation between the PDSS and PSQI, between the PDSS and ESS, between the PDSS and GDS, between the PDSS and HAMA, between the PDSS and the disease durations, and between the PDSS and the LDE, respectively. The Chinese version of PDSS met some basic standards required for sleep disorders measures. It could lead to better understanding the sleep disorders of PD of China in future studies.

Parkinsonism after chronic occupational exposure to glyphosate

As a broad-spectrum herbicide employed to kill weeds, glyphosate (N-(phosphonomethyl) glycine) is typically either sprayed to be absorbed through the leaves, injected into the trunk, or applied to the stump of a tree, and is also used to control vegetation around transmission towers, pipelines, water drainage channels, public squares, and streets throughout the world [1]. In China, glyphosate is popularly used as a hypotoxic weed-killer in rural areas. Every year, there are reports of acute intoxication of glyphosate due to attempted suicide or error in usage among adults and children [2]. Symptoms in such cases are frequently reported as consisting of digestive tract dysfunction, circulatory and respiratory failure, and liver and kidney damage [1,2]. Neurological involvement, in particular extrapyramidal symptoms and signs including limb rigidity and resting tremor, has only been reported following a few isolated events rather than in the setting of chronic occupational exposure [3]. Here we report a patient with parkinsonism following chronic occupational exposure to glyphosate. A previously healthy 44year-old woman presented with rigidity, slowness and resting tremor in all four limbs with no impairment of short-termmemory, after sustaining long term chemical exposure to glyphosate for 3 years as a worker in a chemical factory. The chemical plant produced a range of herbicides including: glyphosate, gibberellins, and dimethyl hydrogen phosphite; however, the patient worked exclusively in the glyphosate production division. She only wore basic protection such as gloves or a face mask for 50 h each week in the plant where glyphosate vapor was generated. She frequently felt weak. Twomonths before she came to our clinic, she had experienced severe dizziness and blurred vision. After being diagnosed by the local doctor with cervical spondylosis, the patient received treatment with DAN-SHEN (salvia) injections for one week without any improvement. Physical examination revealed a parkinsonian syndrome. There was no known family history of neurological or other relevant disorders. The patient had consumed no other medications or herbal preparations before the onset of symptoms. Resting tremor in the left and right limbs, global akinesia and rigidity were observed, but without a “cogwheel phenomenon” or postural instability. The severity of symptoms was Hoehn and Yahr stage 2 and the UPDRS total score was 14, including UPDRS-I 0, UPDRS-II 1, UPDRS-III 12, UPDRS-IV 1. There were no autonomic or eye movement abnormalities, and the rest of the neurological examination

Visual hallucinations and associated factors in Chinese patients with Parkinson’s disease: Roles of RBD and visual pathway deficit ☆

Visual hallucinations (VH) occur frequently in the natural course of Parkinson’s disease (PD) and result from side effects of antiparkinsonian agents, with the prevalence of VH varying from 8% to 40% based on previous investigations [1–3]. However, there is so far no relevant study of the prevalence and associated factors of VH in PD patients in China. In addition, there are no consensus which has been reached to explain the mechanism of VH. An integrative model suggested that VH could be considered as a dysregulation of the gating and filtering of external perception and internal image production, which was involved dysfunction of the visual pathways [4,5]. To validate the current theory for VH and explore the influence of Rapid Eye Movement Behavior Disorder (RBD) and visual pathway deficit in the pathogenetic mechanisms of VH in PD, we conducted a pilot study investigating VH and associated factors in Chinese PD patients.