Current Alzheimer disease research highlights: evidence for novel risk factors / 中华医学杂志(英文版)

Alzheimer disease (AD) is the most common type of dementia characterized by the progressive cognitive and social decline. Clinical drug targets have heavily focused on the amyloid hypothesis, with amyloid beta (Aβ), and tau proteins as key pathophysiologic markers of AD. However, no effective treatment has been developed so far, which prompts researchers to focus on other aspects of AD beyond Aβ, and tau proteins. Additionally, there is a mounting epidemiologic evidence that various environmental factors influence the development of dementia and that dementia etiology is likely heterogenous. In the past decades, new risk factors or potential etiologies have been widely studied. Here, we review several novel epidemiologic and clinical research developments that focus on sleep, hypoxia, diet, gut microbiota, and hearing impairment and their links to AD published in recent years. At the frontiers of AD research, these findings and updates could be worthy of further attention.

Clinical Characteristics, Radiological Features and Gene Mutation in 10 Chinese Families with Spinocerebellar Ataxias / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Spinocerebellar ataxias (SCAs) are a group of neurodegenerative disorders that primarily cause the degeneration in the cerebellum, spinal cord, and brainstem. We study the clinical characteristics, radiological features and gene mutation in Chinese families with SCAs.</p><p><b>METHODS</b>In this study, we investigated 10 SCAs Chinese families with SCA1, SCA3/Machado-Joseph disease (MJD), SCA7, SCA8. There were 27 people who were genetically diagnosed as SCA, of which 21 people showed clinical symptoms, and 6 people had no clinical phenotype that we called them presymptomatic patients. In addition, 3 people with cerebellar ataxia and cataracts were diagnosed according to the Harding diagnostic criteria but failed to be recognized as SCAs on genetic testing. Clinical characteristic analyses of each type of SCAs and radiological examinations were performed.</p><p><b>RESULTS</b>We found that SCA3/MJD was the most common subtype in Han population in China, and the ratio of the pontine tegmentum and the posterior fossa area was negatively correlated with the number of cytosine-adenine-guanine (CAG) repeats; the disease duration was positively correlated with the International Cooperative Ataxia Rating Scale score; and the CAG repeats number of abnormal alleles was negatively correlated with the age of onset.</p><p><b>CONCLUSIONS</b>Collectively our study is a systematic research on SCAs in China, which may help for the clinical diagnosis and prenatal screening of this disease, and it may also aid toward better understanding of this disease.</p>

Dopamine Agonists Exert Nurr1-inducing Effect in Peripheral Blood Mononuclear Cells of Patients with Parkinson's Disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Nurr1 plays an essential role in the development, survival, and function maintenance of midbrain dopaminergic (DA) neurons, and it is a potential target for Parkinson's disease (PD). Nurr1 mRNA can be detected in peripheral blood mononuclear cells (PBMCs), but whether there is any association of altered Nurr1 expression in PBMC with the disease and DA drug treatments remains elusive. This study aimed to measure the Nurr1 mRNA level in PBMC and evaluate the effect of Nurr1 expression by DA agents in vivo and in vitro.</p><p><b>METHODS</b>The mRNA levels of Nurr1 in PBMC of four subgroups of 362 PD patients and 193 healthy controls (HCs) using real-time polymerase chain reaction were measured. The nonparametric Mann-Whitney U-test and Kruskal-Wallis test were performed to evaluate the differences between PD and HC, as well as the subgroups of PD. Multivariate linear regression analysis was used to evaluate the independent association of Nurr1 expression with Hoehn and Yahr scale, age, and drug treatments. Besides, the Nurr1 expression in cultured PBMC was measured to determine whether DA agonist pramipexole affects its mRNA level.</p><p><b>RESULTS</b>The relative Nurr1 mRNA levels in DA agonists treated subgroup were significant higher than those in recent-onset cases without any anti-PD treatments (de novo) (P < 0.001) and HC groups (P < 0.010), respectively. Furthermore, the increase in Nurr1 mRNA expression was seen in DA agonist and L-dopa group. Multivariate linear regression showed DA agonists, L-dopa, and DA agonists were independent predictors correlated with Nurr1 mRNA expression level in PBMC. In vitro, in the cultured PBMC treated with 10 μmol/L pramipexole, the Nurr1 mRNA levels were significantly increased by 99.61%, 71.75%, 73.16% in 2, 4, and 8 h, respectively (P < 0.001).</p><p><b>CONCLUSIONS</b>DA agonists can induce Nurr1 expression in PBMC, and such effect may contribute to DA agonists-mediated neuroprotection on DA neurons.</p>

Progress in Diagnosing Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like Episodes / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a progressive, multisystem affected mitochondrial disease associated with a number of disease-related defective genes. MELAS has unpredictable presentations and clinical course, and it can be commonly misdiagnosed as encephalitis, cerebral infarction, or brain neoplasms. This review aimed to update the diagnosis progress in MELAS, which may provide better understanding of the disease nature and help make the right diagnosis as well.</p><p><b>DATA SOURCES</b>The data used in this review came from published peer review articles from October 1984 to October 2014, which were obtained from PubMed. The search term is "MELAS".</p><p><b>STUDY SELECTION</b>Information selected from those reported studies is mainly based on the progress on clinical features, blood biochemistry, neuroimaging, muscle biopsy, and genetics in diagnosing MELAS.</p><p><b>RESULTS</b>MELAS has a wide heterogeneity in genetics and clinical manifestations. The relationship between mutations and phenotypes remains unclear. Advanced serial functional magnetic resonance imaging (MRI) can provide directional information on this disease. Muscle biopsy has meaningful value in diagnosing MELAS, which shows the presence of ragged red fibers and mosaic appearance of cytochrome oxidase negative fibers. Genetic studies have reported that approximately 80% of MELAS cases are caused by the mutation m.3243A>G of the mitochondrial transfer RNA (Leu (UUR)) gene (MT-TL1).</p><p><b>CONCLUSIONS</b>MELAS involves multiple systems with variable clinical symptoms and recurrent episodes. The prognosis of MELAS patients depends on timely diagnosis. Therefore, overall diagnosis of MELAS should be based on the maternal inheritance family history, clinical manifestation, and findings from serial MRI, muscle biopsy, and genetics.</p>

Association of serum uric acid levels with the progression of Parkinson's disease in Chinese patients / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Uric acid (UA) is suspected to play a neuro-protective role in Parkinson's disease (PD). This study aimed to evaluate whether the serum UA level was associated with the disease progression of PD in a relatively large population of Chinese patients.</p><p><b>METHODS</b>Serum UA levels were measured from 411 Chinese PD patients and 396 age-matched controls; following the uric acid colorimetric method, the serum creatinine (Scr) levels were also measured to reduce the bias caused by possible differences in renal excretion function. The disease progression was scored by Hoehn and Yahr (H&Y) scales and disease durations; PD group was divided into 3 subgroups according to H&Y scales. Independent-samples t test was performed to analyze the differences between PD group and control group. Multiple analysis of covariance was performed to analyze the differences between PD subgroups. Spearman rank-correlation was performed to evaluate the associations between serum UA or Scr level and disease progression.</p><p><b>RESULTS</b>PD patients were found to have significantly lower levels of serum UA than controls ((243.38 ± 78.91) vs. (282.97 ± 90.80) µmol/L, P < 0.01). As the disease progression, the serum UA levels were gradually reduced. There was a significantly inverse correlation of UA levels with H&Y scales (Rs = -0.429, P < 0.01) and disease duration (Rs = -0.284, P < 0.01) in PD patients of both females and males. No significant difference of the Scr level between PD patients and controls was found ((70.01 ± 14.70) vs. (69.84 ± 16.46) µmol/L), and the Scr level was not involved in disease progression.</p><p><b>CONCLUSION</b>Lower serum UA levels may possess a higher risk of PD, which may be a potential useful biomarker to indicate the progression of PD.</p>

ATP depletion is the major cause of MPP+ induced dopamine neuronal death and worm lethality in alpha-synuclein transgenic C. elegans / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To investigate the toxic effect of environmental neurotoxin MPP+ to C. elegans and identify the mechanisms that cause the toxicity.</p><p><b>METHODS</b>Human alpha-synuclein transgenic C. elegans was used as the animal model, the toxic effect of MPP+ to dopamine (DA) neurons and the lifespan of worms was tested. The worms were feed with OP50 to determine whether ATP increase can rescue the worm from toxicity. ATP level and aberrant protein accumulation were analyzed in the MPP+ treated worms with or without OP50 addition.</p><p><b>RESULTS</b>We found that MPP+ induced DA cell death and worm lethality, which could be prevented by OP50 treatment. OP50 exerted the protective effect by up-regulating ATP level, even though it also induced accumulation of alpha-synuclein. Despite the undefined role of protein aggregation to the cell death, our results showed that the toxicity of MPP+ was mainly caused by the ATP depletion in the alpha-synuclein transgenic C. elegans.</p><p><b>CONCLUSION</b>MPP+ could induce DA neuronal death and worm lethality in alpha-synuclein transgenic C. elegans; Compared with the aggregation of alpha-synuclein, the major cause of MPP+ toxicity appeared due to ATP depletion.</p>

Genetics and clinical features of dystonia / 上海第二医科大学学报

Dystonia is a common movement disorder characterized by abnormal gestures and involuntary movement as a result of incoordinate contraction of agonistic and antagonistic muscles.The underlying pathogenesis is very complicated and there are various clinical manifestations.The recent findings in genetics and clinical features of primary dystonia,dystonia-plus syndrome and heredodegenerative dystonia are introduced in this paper.

Epigallocatechin gallate protects dopaminergic neurons against 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity by inhibiting microglial cell activation / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe whether the dopaminergic neuroprotective effect of (-)-epigallocatechin gallate (EGCG) is associated with its inhibition of microglial cell activation in vivo.</p><p><b>METHODS</b>The effects of EGCG at different doses on dopaminergic neuronal survival were tested in a methyl-4-phenyl-pyridinium (MPP+)-induced dopaminergic neuronal injury model in the primary mesencephalic cell cultures. With unbiased stereological method, tyrosine hydroxylase-immunoreactive (TH-ir) cells were counted in the A8, A9 and A10 regions of the substantia nigra (SN) in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated C57BL/6 mice. The effect of EGCG on microglial activation in the SN was also investigated.</p><p><b>RESULTS</b>Pretreatment with EGCG (1 to 100 micromol/L) significantly attenuated MPP+-induced TH-ir cell loss by 22.2% to 80.5% in the mesencephalic cell cultures. In MPTP-treated C57BL/6 mice, EGCG at a low concentration (1 mg/kg) provided significant protection against MPTP-induced TH-ir cell loss by 50.9% in the whole nigral area and by 71.7% in the A9 region. EGCG at 5 mg/kg showed more prominent protective effect than at 1 or 10 mg/kg. EGCG pretreatment significantly inhibited microglial activation and CD11b expression induced by MPTP.</p><p><b>CONCLUSION</b>EGCG exerts potent dopaminergic neuroprotective activity by means of microglial inhibition, which shed light on the potential use of EGCG in treatment of Parkinson's disease.</p>

C. elegans as a model system for Parkinson disease / 神经科学通报·英文版

Parkinson disease (PD) is characterized by the selective loss of dopaminergic neurons in the substantia nigra. Although investigation in mammalian animal models of PD has enhanced our understanding of PD, the complexity of the mammalian nervous system and our inability to visualize DA neurons in vivo restricts the advances in elucidating the molecular mechanisms of PD. Conservation between C. elegans and mammals in genomic, biosynthetic and metabolic pathways as well as the advantages of observing DA neurons morphology in vivo and the ease of transgenic and genetic manipulation make C. elegans an excellent model organism for PD.

Novel splicing variant of the human orphan nuclear receptor Nurr1 gene / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Nurr1 is a member of the nuclear receptor superfamily of transcription factors. The objective of the present study was to identify novel splicing variants of the gene in neuronal and non-neuronal tissues and determine their functions.</p><p><b>METHODS</b>Reverse transcription-polymerase chain reaction (RT-PCR) analysis was used to screen for Nurr1 splice variants in the adult human central nervous system (CNS) and in other tissues such as lymphocytes, and liver, muscle, and kidney cells. Functional assays of the variants were performed by measuring Nurr1 response element (NuRE) transcriptional activity in vitro.</p><p><b>RESULTS</b>In this study, the authors identified a novel splicing variant of Nurr1 within exon 5, found in multiple adult human tissues, including lymphocytes, and liver, muscle, and kidney cells, but not in the brain or spinal cord. Sequencing analysis showed the variant has a 75 bp deletion between nucleotides 1402 and 1476. A functional assay of the Nurr1-c splicing variant, performed by measuring NuRE transcriptional activity in vitro, detected a 39% lower level of luciferase (LUC) activity (P < 0.05).</p><p><b>CONCLUSION</b>A novel splicing variant of Nurr1 exists in human non-neuronal tissues and functional assays suggest that the variant may act as an alternate transcription regulator.</p>