Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is k...Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.展开更多
In clinical specialties focusing on neurological disorders,there is a need for comprehensive and integrated non-invasive,sensitive,and specific testing methods.Both Parkinson's disease and multiple system atrophy ...In clinical specialties focusing on neurological disorders,there is a need for comprehensive and integrated non-invasive,sensitive,and specific testing methods.Both Parkinson's disease and multiple system atrophy are classified asα-synucleinopathies,characterized by abnormal accumulation ofα-synuclein protein,which provides a shared pathological background for their comparative study.In addition,both Parkinson's disease and multiple system atrophy involve neuronal death,a process that may release circulating cell–free DNA(cfDNA)into the bloodstream,leading to specific alterations.This premise formed the basis for investigating cell–free DNA as a potential biomarker.Cellfree DNA has garnered attention for its potential pathological significance,yet its characteristics in the context of Parkinson's disease and multiple system atrophy are not fully understood.This study investigated the total concentration,nonapoptotic level,integrity,and cellfree DNA relative telomere length of cell-free DNA in the peripheral blood of 171 participants,comprising 76 normal controls,62 patients with Parkinson's disease,and 33 patients with multiple system atrophy.In our cohort,75.8%of patients with Parkinson's disease(stage 1–2 of Hoehn&Yahr)and 60.6%of patients with multiple system atrophy(disease duration less than 3 years)were in the early stages.The diagnostic potential of the cell-free DNA parameters was evaluated using receiver operating characteristic(ROC)analysis,and their association with disease prevalence was examined through logistic regression models,adjusting for confounders such as age,sex,body mass index,and education level.The results showed that cell-free DNA integrity was significantly elevated in both Parkinson's disease and multiple system atrophy patients compared with normal controls(P<0.001 for both groups),whereas cell-free DNA relative telomere length was markedly shorter(P=0.003 for Parkinson's disease and P=0.010 for multiple system atrophy).Receiver operating characteristic analysis indicated that both cell-free DNA integrity and cell-free DNA relative telomere length possessed good diagnostic accuracy for differentiating Parkinson's disease and multiple system atrophy from normal controls.Specifically,higher cell-free DNA integrity was associated with increased risk of Parkinson's disease(odds ratio[OR]:5.72;95%confidence interval[CI]:1.54–24.19)and multiple system atrophy(OR:10.10;95%CI:1.55–122.98).Conversely,longer cell-free DNA relative telomere length was linked to reduced risk of Parkinson's disease(OR:0.16;95%CI:0.04–0.54)and multiple system atrophy(OR:0.10;95%CI:0.01–0.57).These findings suggest that cell-free DNA integrity and cellfree DNA relative telomere length may serve as promising biomarkers for the early diagnosis of Parkinson's disease and multiple system atrophy,potentially reflecting specific underlying pathophysiological processes of these neurodegenerative disorders.展开更多
Inertial system platforms are a kind of important precision devices,which have the characteristics of difficult acquisition for state data and small sample scale.Focusing on the model optimization for data-driven faul...Inertial system platforms are a kind of important precision devices,which have the characteristics of difficult acquisition for state data and small sample scale.Focusing on the model optimization for data-driven fault state prediction and quantitative degreemeasurement,a fast small-sample supersphere one-class SVMmodelingmethod using support vectors pre-selection is systematically studied in this paper.By theorem-proving the irrelevance between themodel’s learning result and the non-support vectors(NSVs),the distribution characters of the support vectors are analyzed.On this basis,a modeling method with selected samples having specific geometry character fromthe training sets is also proposed.The method can remarkably eliminate theNSVs and improve the algorithm’s efficiency.The experimental results testify that the scale of training samples and the modeling time consumption both give a sharply decrease using the support vectors pre-selection method.The experimental results on inertial devices also show good fault prediction capability and effectiveness of quantitative anomaly measurement.展开更多
To the Editor:Accumulating evidence has shown that the preclinical stage of Alzheimer’s disease(AD)(i.e.,asymptomatic amyloidosis)lasts for decades before the onset of cognitive symptoms,providing a large window for ...To the Editor:Accumulating evidence has shown that the preclinical stage of Alzheimer’s disease(AD)(i.e.,asymptomatic amyloidosis)lasts for decades before the onset of cognitive symptoms,providing a large window for early intervention.Amyloid pathology,the earliest pathological change associated with AD,can be detected in vivo with cerebrospinal fluid(CSF)analysis or positron emission tomography(PET),and its presence is necessary for the diagnosis of preclinical AD(pre-AD).However,both PET scans and CSF analyses are expensive,hampering their use in large-scale screening.Thus,blood-based biomarkers are desirable alternatives,as they are cost-effective and not invasive.展开更多
基金supported by the National Key Research&Development Program of China,Nos.2021YFC2501205(to YC),2022YFC24069004(to JL)the STI2030-Major Project,Nos.2021ZD0201101(to YC),2022ZD0211800(to YH)+2 种基金the National Natural Science Foundation of China(Major International Joint Research Project),No.82020108013(to YH)the Sino-German Center for Research Promotion,No.M-0759(to YH)a grant from Beijing Municipal Science&Technology Commission(Beijing Brain Initiative),No.Z201100005520018(to JL)。
文摘Several promising plasma biomarker proteins,such as amyloid-β(Aβ),tau,neurofilament light chain,and glial fibrillary acidic protein,are widely used for the diagnosis of neurodegenerative diseases.However,little is known about the long-term stability of these biomarker proteins in plasma samples stored at-80°C.We aimed to explore how storage time would affect the diagnostic accuracy of these biomarkers using a large cohort.Plasma samples from 229 cognitively unimpaired individuals,encompassing healthy controls and those experiencing subjective cognitive decline,as well as 99 patients with cognitive impairment,comprising those with mild cognitive impairment and dementia,were acquired from the Sino Longitudinal Study on Cognitive Decline project.These samples were stored at-80°C for up to 6 years before being used in this study.Our results showed that plasma levels of Aβ42,Aβ40,neurofilament light chain,and glial fibrillary acidic protein were not significantly correlated with sample storage time.However,the level of total tau showed a negative correlation with sample storage time.Notably,in individuals without cognitive impairment,plasma levels of total protein and tau phosphorylated protein threonine 181(p-tau181)also showed a negative correlation with sample storage time.This was not observed in individuals with cognitive impairment.Consequently,we speculate that the diagnostic accuracy of plasma p-tau181 and the p-tau181 to total tau ratio may be influenced by sample storage time.Therefore,caution is advised when using these plasma biomarkers for the identification of neurodegenerative diseases,such as Alzheimer's disease.Furthermore,in cohort studies,it is important to consider the impact of storage time on the overall results.
基金supported by the National Key Research and Development Program of China,No.2021YFC2501205(to YC)the Science and Technology Innovation 2030 project,No.2021ZD0201101(to YC)+1 种基金the National Natural Science Foundation of China,Nos.82201409(to YL),82201401(to CH)the Xuanwu Youth Development Project,No.QNPY2021011(to CH)。
文摘In clinical specialties focusing on neurological disorders,there is a need for comprehensive and integrated non-invasive,sensitive,and specific testing methods.Both Parkinson's disease and multiple system atrophy are classified asα-synucleinopathies,characterized by abnormal accumulation ofα-synuclein protein,which provides a shared pathological background for their comparative study.In addition,both Parkinson's disease and multiple system atrophy involve neuronal death,a process that may release circulating cell–free DNA(cfDNA)into the bloodstream,leading to specific alterations.This premise formed the basis for investigating cell–free DNA as a potential biomarker.Cellfree DNA has garnered attention for its potential pathological significance,yet its characteristics in the context of Parkinson's disease and multiple system atrophy are not fully understood.This study investigated the total concentration,nonapoptotic level,integrity,and cellfree DNA relative telomere length of cell-free DNA in the peripheral blood of 171 participants,comprising 76 normal controls,62 patients with Parkinson's disease,and 33 patients with multiple system atrophy.In our cohort,75.8%of patients with Parkinson's disease(stage 1–2 of Hoehn&Yahr)and 60.6%of patients with multiple system atrophy(disease duration less than 3 years)were in the early stages.The diagnostic potential of the cell-free DNA parameters was evaluated using receiver operating characteristic(ROC)analysis,and their association with disease prevalence was examined through logistic regression models,adjusting for confounders such as age,sex,body mass index,and education level.The results showed that cell-free DNA integrity was significantly elevated in both Parkinson's disease and multiple system atrophy patients compared with normal controls(P<0.001 for both groups),whereas cell-free DNA relative telomere length was markedly shorter(P=0.003 for Parkinson's disease and P=0.010 for multiple system atrophy).Receiver operating characteristic analysis indicated that both cell-free DNA integrity and cell-free DNA relative telomere length possessed good diagnostic accuracy for differentiating Parkinson's disease and multiple system atrophy from normal controls.Specifically,higher cell-free DNA integrity was associated with increased risk of Parkinson's disease(odds ratio[OR]:5.72;95%confidence interval[CI]:1.54–24.19)and multiple system atrophy(OR:10.10;95%CI:1.55–122.98).Conversely,longer cell-free DNA relative telomere length was linked to reduced risk of Parkinson's disease(OR:0.16;95%CI:0.04–0.54)and multiple system atrophy(OR:0.10;95%CI:0.01–0.57).These findings suggest that cell-free DNA integrity and cellfree DNA relative telomere length may serve as promising biomarkers for the early diagnosis of Parkinson's disease and multiple system atrophy,potentially reflecting specific underlying pathophysiological processes of these neurodegenerative disorders.
基金the National Natural Science Foundation of China(Grant No.61403397)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant Nos.2020JM-358,2015JM6313).
文摘Inertial system platforms are a kind of important precision devices,which have the characteristics of difficult acquisition for state data and small sample scale.Focusing on the model optimization for data-driven fault state prediction and quantitative degreemeasurement,a fast small-sample supersphere one-class SVMmodelingmethod using support vectors pre-selection is systematically studied in this paper.By theorem-proving the irrelevance between themodel’s learning result and the non-support vectors(NSVs),the distribution characters of the support vectors are analyzed.On this basis,a modeling method with selected samples having specific geometry character fromthe training sets is also proposed.The method can remarkably eliminate theNSVs and improve the algorithm’s efficiency.The experimental results testify that the scale of training samples and the modeling time consumption both give a sharply decrease using the support vectors pre-selection method.The experimental results on inertial devices also show good fault prediction capability and effectiveness of quantitative anomaly measurement.
基金supported by grants from the National Natural Science Foundation of China(Nos.82020108013 and 82001773)National Key Research and Development Program of China(No.2022YFC24069004)+1 种基金Beijing Brain Initiative from Beijing Municipal Science&Technology Commission(No.Z201100005520018)STI2030-Major Projects(No.2022ZD0211800)
文摘To the Editor:Accumulating evidence has shown that the preclinical stage of Alzheimer’s disease(AD)(i.e.,asymptomatic amyloidosis)lasts for decades before the onset of cognitive symptoms,providing a large window for early intervention.Amyloid pathology,the earliest pathological change associated with AD,can be detected in vivo with cerebrospinal fluid(CSF)analysis or positron emission tomography(PET),and its presence is necessary for the diagnosis of preclinical AD(pre-AD).However,both PET scans and CSF analyses are expensive,hampering their use in large-scale screening.Thus,blood-based biomarkers are desirable alternatives,as they are cost-effective and not invasive.
