27 results on '"M. Chakroun"'
Search Results
2. Migration of an intrauterine device to the posterior urethra with stone formation: a case report.
- Author
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Chuanfeng Liu, Yongqiang Xia, Qingtan Pang, Zichao Zhao, and Jianfang Zhao
- Published
- 2024
- Full Text
- View/download PDF
3. An indicator of the view of time passing: the development and validation of the metacognitive knowledge of time passing scale (MKTPS) in Chinese college students.
- Author
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Xide Yu, Cheng Lu, Yaju Ma, Li Huang, and Chenyang Wu
- Subjects
TIME perspective ,EXPLORATORY factor analysis ,CONFIRMATORY factor analysis ,CHINESE-speaking students ,STATISTICAL reliability ,METACOGNITION - Abstract
How we view the passage of past time determines how we face time itself as well as our futures, which has a strong impact particularly during the highly creative and malleable college years. Chinese culture cherishes time deeply, and for centuries there has been a tradition of "educating children and youth to inspect the passage of time." However, in today's age of information and intelligence, time has shown a trend toward fragmentation. How do contemporary Chinese college students view the passage of time, and what structures or content does it contain? The answer to this question remains uncertain, necessitating further exploration. Following Flavell's theory of metacognitive knowledge (MK), we adopted a semi-structured interview method and used the results to first outline the basic structure of Chinese college students' view of time passing, identifying four major aspects: priming aftereffect, life touching, positive promotion, and negative inhibition. Then, using the initial four-dimensional structure as a starting point, we developed the Metacognitive Knowledge of Time Passing Scale (MKTPS), and carried out exploratory factor analysis and confirmatory factor analysis to test its fit. The results showed that the fourfactor scale and its 22 items had a good fit to the data. Third, the reliability and validity of the self-developed scale were tested. The results show that the internal consistency, split-half, and retest reliability of the MKTPS are good (all rs > 0.60). The construct validity of the MKTPS is also good (r
between subscales is 0.33-0.60, rbetween subscales and total scale is 0.64-0.87), the convergent validity with Zimbardo's negative past time perspective is high (r = 0.37), and the discriminant validity with Zimbardo's future time perspective is significant (r = 0.18). Regarding criterion correlation validity, the total scores of the MKTPS have a significantly higher positive correlation with those of the time management disposition (TMD) scale (r = 0.45). Future points for studying the view of time passing in adults of all ages and across cultures field and shortcomings of the current study are also discussed. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
4. Crosstalk between ubiquitin ligases and ncRNAs drives cardiovascular disease progression.
- Author
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Jia-Rui You, Zeng-Jin Wen, Jia-Wei Tian, Xiao-Bing Lv, Rong Li, Shu-Ping Li, Hui Xin, Pei-Feng Li, Yin-Feng Zhang, and Rui Zhang
- Subjects
UBIQUITIN ligases ,SMALL interfering RNA ,LINCRNA ,CARDIOVASCULAR diseases ,CIRCULAR RNA - Abstract
Cardiovascular diseases (CVDs) are multifactorial chronic diseases and have the highest rates of morbidity and mortality worldwide. The ubiquitin-proteasome system (UPS) plays a crucial role in posttranslational modification and quality control of proteins, maintaining intracellular homeostasis via degradation of misfolded, short-lived, or nonfunctional regulatory proteins. Noncoding RNAs (ncRNAs, such as microRNAs, long noncoding RNAs, circular RNAs and small interfering RNAs) serve as epigenetic factors and directly or indirectly participate in various physiological and pathological processes. NcRNAs that regulate ubiquitination or are regulated by the UPS are involved in the execution of target protein stability. The cross-linked relationship between the UPS, ncRNAs and CVDs has drawn researchers' attention. Herein, we provide an update on recent developments and perspectives on how the crosstalk of the UPS and ncRNAs affects the pathological mechanisms of CVDs, particularly myocardial ischemia/reperfusion injury, myocardial infarction, cardiomyopathy, heart failure, atherosclerosis, hypertension, and ischemic stroke. In addition, we further envision that RNA interference or ncRNA mimics or inhibitors targeting the UPS can potentially be used as therapeutic tools and strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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5. Alternative in-vivo models of mucormycosis.
- Author
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Scheler, Jakob and Binder, Ulrike
- Abstract
Mucormycosis is still regarded a rare fungal infection, but the high incidences of COVID-associated cases in India and other countries have shown its potential threat to large patient cohorts. In addition, infections by these fast-growing fungi are often fatal and cause disfigurement, badly affecting patients’ lives. In advancing our understanding of pathogenicity factors involved in this disease, to enhance the diagnostic toolset and to evaluate novel treatment regimes, animal models are indispensable. As ethical and practical considerations typically favor the use of alternative model systems, this review provides an overview of alternative animal models employed for mucormycosis and discusses advantages and limitations of the respective model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Alternative in-vivo models of mucormycosis.
- Author
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Scheler, Jakob and Binder, Ulrike
- Subjects
MUCORMYCOSIS ,MYCOSES ,GREATER wax moth ,SILKWORMS ,DROSOPHILA melanogaster ,ANIMAL models in research - Abstract
Mucormycosis is still regarded a rare fungal infection, but the high incidences of COVID-associated cases in India and other countries have shown its potential threat to large patient cohorts. In addition, infections by these fast-growing fungi are often fatal and cause disfigurement, badly affecting patients' lives. In advancing our understanding of pathogenicity factors involved in this disease, to enhance the diagnostic toolset and to evaluate novel treatment regimes, animal models are indispensable. As ethical and practical considerations typically favor the use of alternative model systems, this review provides an overview of alternative animal models employed for mucormycosis and discusses advantages and limitations of the respective model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Invasive splenic mucormycosis due to Rhizopus microsporus during chemotherapy for acute monocytic leukemia: a case report and literature review.
- Author
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Xiru Peng, Zixiu Wei, Lijuan Wang, and Juan Cheng
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MUCORMYCOSIS ,LITERATURE reviews ,ACUTE leukemia ,RHIZOPUS ,MYCOSES ,OPPORTUNISTIC infections - Abstract
Mucormycosis is a rare opportunistic fungal infection associated with high mortality that typically occurs in immunocompromised patients. It is difficult to diagnose owing to non-specific clinical manifestations, the serologic index, imaging features, and the limitations of diagnostic methods. The incidence of invasive splenic mucormycosis is extremely rare, with only a few cases documented in the literature. We report a survival case of invasive splenic mucormycosis involving the liver caused by Rhizopus microsporus in a patient during consolidation therapy for acute monocytic leukemia (AML-M5). The patient initially presented with recurrent fever and splenomegaly accompanied by multiple focal hypodensities unresponsive to empiric anti-infective treatment. Splenic mucormycosis was diagnosed by Contrast-Enhanced Ultrasonography (CEUS) and metagenomic next-generation sequencing (mNGS). However, surgical intervention carries a high risk due to the progressive involvement of the liver in invasive splenic mucormycosis. Fortunately, monotherapy with amphotericin B was effective, and the patient underwent allo-HSCT. This case aims to emphasize the importance of utilizing mNGS and CEUS for the timely diagnosis of mucormycosis to help clinicians identify splenic mucormycosis and initiate appropriate therapy as soon as possible to improve therapeutic efficacy and prognosis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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8. The metacognitive experience of time passing in Chinese college students: scale development, structure verification, and influencing factors.
- Author
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Xide Yu, Jiafan Liu, Yaohui Lin, Xianli Chen, and Cheng Lu
- Subjects
CHINESE-speaking students ,METACOGNITION ,STUDENT development ,COLLEGE students ,CONVENIENCE sampling (Statistics) ,STATISTICAL reliability - Abstract
The experience of time passing (ETP) is also the consciousness of the progress of life. ETP contributes to time regulation and life management, which basically conforms to the metacognitive theory. Also, the traditional Chinese cultural approach to time emphasizes ETP. It is an indispensable part of Chinese education and culture to strengthen one’s appreciation of time by emphasizing the passage of time. In combination with the above two points, ETP equals metacognitive experience of time passing (METP) to a certain extent. However, we currently know little about the connotations of METP. To better understand traditional Chinese time culture, and referring to the concept of metacognition and model of time experience as proposed by Western scholars, the current study combined the results of open and semistructured interviews, to explore the structure of METP in Chinese college students and developed a questionnaire with which to measure it. Using convenience sampling, 2,876 college students were recruited, the interview, and the reliability and validity tests were carried out. Five hundred and seventy-nine college students were tested a second time to investigate the correlation validity between METP and Ruminative Responses, time attitude, and meaning in life. The results led to the development of the METP Scale which contains 15 items and assesses two factors: ruminative and emotional experience of time passing. The two-factor model was well fitted, and invariable in measurements across gender, grade, and major. The internal consistency coefficients of the scale and its two factors ranged from 0.82 to 0.89, the half-point reliability between 0.76 and 0.88, and the retest reliability ranged from 0.77 to 0.78. METP Scale has good correlation validity, meanwhile, the results of regression analysis showed that symptom rumination, positive past, negative present, positive future, and searching for meaning in life significantly predict the intensity of METP. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
9. Dynamics of a model for the degradation mechanism of aggregated α-synuclein in Parkinson's disease.
- Author
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Bojie Yang, Zhuoqin Yang, and Lijie Hao
- Subjects
PARKINSON'S disease ,ALPHA-synuclein ,BIFURCATION diagrams ,NEURODEGENERATION - Abstract
Accumulation of the misfolded synaptic protein α-synuclein (αSyn*) is a hallmark of neurodegenerative disease in Parkinson's disease (PD). Recent studies suggest that the autophagy lysosome pathway (ALP) including both the Beclin1-associated and mTOR-signaling pathways is involved in the αSyn* clearance mechanism. In this study, a mathematical model is proposed for the degradation of αSyn* by ALP with the crosstalk element of mTOR. Using codimension-1 bifurcation analysis, the tri-stability of αSyn* is surveyed under three different stress signals and, in addition, consideration is given to the regulatory mechanisms for the Beclin1- and mTOR-dependent rates on αSyn* degradation using the codimension-1 and-2 bifurcation diagrams. It was found that, especially under internal and external oxidative stresses (S
1 ), the bistable switch of the aggregation of αSyn* can be transformed from an irreversible to a reversible condition through the ALP degradation pathways. Furthermore, the robustness of the tri-stable state for the stress S1 to the parameters related to mTOR-mediated ALP was probed. It was confirmed that mTOR-mediated ALP is important for maintaining the essential dynamic features of the tri-stable state. This study may provide a promising avenue for conducting further experiments and simulations of the degradation mechanism of dynamic modeling in PD. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
10. miRNA and antisense oligonucleotide-based α-synuclein targeting as disease-modifying therapeutics in Parkinson's disease.
- Author
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Suvarna, Vasanti, Deshmukh, Kajal, and Murahari, Manikanta
- Subjects
PARKINSON'S disease ,OLIGONUCLEOTIDES ,ALPHA-synuclein ,MICRORNA ,NEURODEGENERATION ,THERAPEUTICS - Abstract
α-synuclein is the synaptic protein majorly involved in neuronal dysfunction and death and it is well known for the last two decades as a hallmark of Parkinson's disease. Alpha-synuclein is involved in neurodegeneration mediated through various neurotoxic pathways, majorly including autophagy or lysosomal dysregulation, mitochondrial disruption, synaptic dysfunction, and oxidative stress. Moreover, the alpha-synuclein aggregation has been associated with the development of several neurodegenerative conditions such as various forms of Parkinson's disease. The recent discovery in oligonucleotide chemistry has developed potential alpha-synuclein targeting molecules for the treatment of neurodegenerative diseases. The present review article focuses on recent advances in the applications of oligonucleotides acting via alpha-synuclein targeting mechanisms and their implication in combating Parkinson's disease. Moreover, the article emphasizes the potential of miRNAs, and antisense oligonucleotides and the challenges associated with their use in the therapeutical management of Parkinson's disease. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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- View/download PDF
11. A minute fraction of α-synuclein in extracellular vesicles may be a major contributor to α-synuclein spreading following autophagy inhibition.
- Author
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Taha, Hash Brown, Kearney, Brian, and Bitan, Gal
- Subjects
EXTRACELLULAR vesicles ,ALPHA-synuclein ,AUTOPHAGY ,FRACTIONS - Published
- 2022
- Full Text
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12. Memory for the Future: Psychodynamic Approach to Time and Self Through the Default Network.
- Author
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Cieri, Filippo
- Subjects
PSYCHODYNAMIC psychotherapy ,TIME perception ,FUNCTIONAL magnetic resonance imaging ,COGNITIVE neuroscience ,ALZHEIMER'S disease ,SELF ,DEFAULT (Finance) - Abstract
Time exists in us, and our self exists in time. Our self is affected and shaped by time to the point that a better understanding of the former can aid the understanding of the latter. Psychoanalysis works through self and time, where the self is composed of the biopsychosocial history (the past) of the individual and able to map a trajectory for the future. The psychoanalytic relationship starts from a "measurement": an active process able to alter the system being measured—the self—continuously built over time. This manuscript, starts from the philosophical and scientific tradition of a proximity between time and self, suggesting a neural overlapping at the Default Network. A historical and scientific background will be introduced, proposing a multidisciplinary dimension that has characterized the birth of psychoanalysis (its past), influencing its present and future in the dialogue with physics and neuroscience. After a historical scientific introduction, a neural entanglement between past and future at the Default Network level will be proposed, tracing a link with the self at the level of this network. This hypothesis will be supported by studies in cognitive neurosciences and functional neuroimaging which have used the resting state functional Magnetic Resonance Imaging. The ontogenetic development of time perception will be discussed, consistent with self-development and the Default Network's function. The most common form of dementia, the Alzheimer's Disease, in which the perception of time is brutally impaired together with a loss of the self's functions will be proposed to support this idea. Finally, the potential theoretical and clinical significance for psychoanalysis and psychodynamic neurosciences, will be discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Contribution of Autophagy-Lysosomal Pathway in the Exosomal Secretion of Alpha-Synuclein and Its Impact in the Progression of Parkinson's Disease.
- Author
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Sepúlveda, Denisse, Cisternas-Olmedo, Marisol, Arcos, Javiera, Nassif, Melissa, and Vidal, René L.
- Subjects
PARKINSON'S disease ,EXOSOMES ,ALPHA-synuclein ,SECRETION ,DOPAMINERGIC neurons - Abstract
Parkinson's disease (PD) is caused by the degeneration of dopaminergic neurons due to an accumulation of intraneuronal abnormal alpha-synuclein (α-syn) protein aggregates. It has been reported that the levels of exosomal α-syn of neuronal origin in plasma correlate significantly with motor dysfunction, highlighting the exosomes containing α-syn as a potential biomarker of PD. In addition, it has been found that the selective autophagy-lysosomal pathway (ALP) contributes to the secretion of misfolded proteins involved in neurodegenerative diseases. In this review, we describe the evidence that supports the relationship between the ALP and α-syn exosomal secretion on the PD progression and its implications in the diagnosis and progression of this pathology. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
14. Testing the Effectiveness of the Health Belief Model in Predicting Preventive Behavior During the COVID-19 Pandemic: The Case of Romania and Italy.
- Author
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Karl, Johannes Alfons, Fischer, Ronald, Druică, Elena, Musso, Fabio, and Stan, Anastasia
- Subjects
HEALTH Belief Model ,COVID-19 pandemic ,HEALTH behavior ,PERCEIVED benefit ,VIRAL transmission - Abstract
We use a cultural psychology approach to examine the relevance of the Health Belief Model (HBM) for predicting a variety of behaviors that had been recommended by health officials during the initial stages of the COVID-19 lockdown for containing the spread of the virus and not overburdening the health system in Europe. Our study is grounded in the assumption that health behavior is activated based on locally relevant perceptions of threats, susceptibility and benefits in engaging in protective behavior, which requires careful attention to how these perceptions might be structured and activated. We assess the validity of the HBM in two European countries that have been relatively understudied, using simultaneous measurements during acute periods of infection in Romania and Italy. An online questionnaire provided a total of (N = 1863) valid answers from both countries. First, to understand individual difference patterns within and across populations, we fit a General Linear Model in which endorsement was predicted by behavior, country, their interaction, and a random effect for participants. Second, we assess the effect of demographics and health beliefs on prevention behaviors by fitting a multi-group path model across countries, in which each behavior was predicted by the observed health belief variables and demographics. Health beliefs showed stronger relationships with the recommended behaviors than demographics. Confirming previously reported relationships, self-efficacy, perceived severity, and perceived benefits were consistently related to the greater adoption of individual behaviors, whereas greater perceived barriers were related to lower adoption of health behaviors. However, we also point to important location specific effects that suggest that local norms shape protective behavior in highly contextualized ways. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
15. The Relationship Between CEO Duality and Business Firms' Performance: The Moderating Role of Firm Size and Corporate Social Responsibility.
- Author
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Mubeen, Riaqa, Han, Dongping, Abbas, Jaffar, Álvarez-Otero, Susana, and Sial, Muhammad Safdar
- Subjects
SOCIAL responsibility of business ,ORGANIZATIONAL performance ,BUSINESS size ,CHIEF executive officers ,BUSINESS enterprises - Abstract
This study focuses on exploring the relationship between chief executive officer (CEO) duality and firm performance. We focus on how the size and corporate social responsibility (CSR) of firms moderate this relationship. In terms of size, business organizations are of two types: small and large firms. This study uses datasets of listed Chinese business firms included in the China Stock Market and Accounting Research database. It employs a generalized method of moment's technique to explore the connection between CEO duality and the performance of Chinese business firms through double mediation effects. Our empirical analysis showed that CEO duality has a significant negative relationship with firm performance. We also explored the moderating effects of firm size (small and large) and CSR practices on the relationship between CEO duality and improved performance of Chinese firms. Large firms and CSR practices showed significant and positive moderating effects on the relationship between CEO duality and firm performance. Conversely, with CEO duality, small firms showed a negative moderating influence on firm performance. This inclusive model provides valuable insights into how the dual role of the CEO of a firm affected the performance of Chinese firms through the moderating role of CSR practices and firm size for better business performance. The study offers empirical and theoretical contributions to the corporate governance literature. This research framework might help researchers in designing robust strategies to evaluate the effects on firm performance. Researchers may gain helpful insights using this methodology. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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16. Case report: Xanthogranulomatous pyelonephritis masquerading as cystic renal cell carcinoma.
- Author
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Mohaghegh P, SM, Wong, RS, Rahimi, M, Shih, F, and Bansal, R
- Published
- 2020
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17. CNS-Derived Blood Exosomes as a Promising Source of Biomarkers: Opportunities and Challenges.
- Author
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Hornung, Simon, Dutta, Suman, and Bitan, Gal
- Subjects
EXOSOMES ,EXTRACELLULAR vesicles ,CENTRAL nervous system ,BIOLOGICAL tags ,NEURODEGENERATION - Abstract
Eukaryotic cells release different types of extracellular vesicles (EVs) including exosomes, ectosomes, and microvesicles. Exosomes are nanovesicles, 30–200 nm in diameter, that carry cell- and cell-state-specific cargo of proteins, lipids, and nucleic acids, including mRNA and miRNA. Recent studies have shown that central nervous system (CNS)-derived exosomes may carry amyloidogenic proteins and facilitate their cell-to-cell transfer, thus playing a critical role in the progression of neurodegenerative diseases, such as tauopathies and synucleinopathies. CNS-derived exosomes also have been shown to cross the blood-brain-barrier into the bloodstream and therefore have drawn substantial attention as a source of biomarkers for various neurodegenerative diseases as they can be isolated via a minimally invasive blood draw and report on the biochemical status of the CNS. However, although isolating specific brain-cell-derived exosomes from the blood is theoretically simple and the approach has great promise, practical details are of crucial importance and may compromise the reproducibility and utility of this approach, especially when different laboratories use different protocols. In this review we discuss the role of exosomes in neurodegenerative diseases, the usefulness of CNS-derived blood exosomes as a source of biomarkers for these diseases, and practical challenges associated with the methodology of CNS-derived blood exosomes and subsequent biomarker analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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18. Environmental Health Research in Africa: Important Progress and Promising Opportunities.
- Author
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Joubert, Bonnie R., Mantooth, Stacey N., and McAllister, Kimberly A.
- Subjects
INDOOR air pollution ,ENVIRONMENTAL health ,ELECTRONIC waste ,PESTICIDES ,PUBLIC health research ,ENVIRONMENTAL exposure ,AIR pollution ,FLUOROALKYL compounds - Abstract
The World Health Organization in 2016 estimated that over 20% of the global disease burden and deaths were attributed to modifiable environmental factors. However, data clearly characterizing the impact of environmental exposures and health endpoints in African populations is limited. To describe recent progress and identify important research gaps, we reviewed literature on environmental health research in African populations over the last decade, as well as research incorporating both genomic and environmental factors. We queried PubMed for peer-reviewed research articles, reviews, or books examining environmental exposures and health outcomes in human populations in Africa. Searches utilized medical subheading (MeSH) terms for environmental exposure categories listed in the March 2018 US National Report on Human Exposure to Environmental Chemicals, which includes chemicals with worldwide distributions. Our search strategy retrieved 540 relevant publications, with studies evaluating health impacts of ambient air pollution (n=105), indoor air pollution (n = 166), heavy metals (n = 130), pesticides (n = 95), dietary mold (n = 61), indoor mold (n = 9), per- and polyfluoroalkyl substances (PFASs, n = 0), electronic waste (n = 9), environmental phenols (n = 4), flame retardants (n = 8), and phthalates (n = 3), where publications could belong to more than one exposure category. Only 23 publications characterized both environmental and genomic risk factors. Cardiovascular and respiratory health endpoints impacted by air pollution were comparable to observations in other countries. Air pollution exposures unique to Africa and some other resource limited settings were dust and specific occupational exposures. Literature describing harmful health effects of metals, pesticides, and dietary mold represented a context unique to Africa. Studies of exposures to phthalates, PFASs, phenols, and flame retardants were very limited. These results underscore the need for further focus on current and emerging environmental and chemical health risks as well as better integration of genomic and environmental factors in African research studies. Environmental exposures with distinct routes of exposure, unique co-exposures and co-morbidities, combined with the extensive genomic diversity in Africa may lead to the identification of novel mechanisms underlying complex disease and promising potential for translation to global public health. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
19. Exosome Production Is Key to Neuronal Endosomal Pathway Integrity in Neurodegenerative Diseases.
- Author
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Mathews, Paul M. and Levy, Efrat
- Subjects
NEURODEGENERATION ,CENTRAL nervous system ,PROTEIN precursors ,APOLIPOPROTEIN E ,MEMBRANE lipids ,BLOOD-brain barrier - Abstract
Dysfunction of the endosomal–lysosomal system is a prominent pathogenic factor in Alzheimer's disease (AD) and other neurodevelopmental and neurodegenerative disorders. We and others have extensively characterized the neuronal endosomal pathway pathology that results from either triplication of the amyloid-β precursor protein (APP) gene in Down syndrome (DS) or from expression of the apolipoprotein E ε4 allele (APOE4), the greatest genetic risk factor for late-onset AD. More recently brain exosomes, extracellular vesicles that are generated within and released from endosomal compartments, have been shown to be altered in DS and by APOE4 expression. In this review, we discuss the emerging data arguing for an interdependence between exosome production and endosomal pathway integrity in the brain. In vitro and in vivo studies indicate that altered trafficking through the endosomal pathway or compromised cargo turnover within lysosomes can affect the production, secretion, and content of exosomes. Conversely, exosome biogenesis can affect the endosomal–lysosomal system. Indeed, we propose that efficient exosome release helps to modulate flux through the neuronal endosomal pathway by decompressing potential "traffic jams." Exosome secretion may have the added benefit of unburdening the neuron's lysosomal system by delivering endosomal–lysosomal material into the extracellular space, where other cell types may contribute to the degradation of neuronal debris. Thus, maintaining robust neuronal exosome production may prevent or mitigate endosomal and lysosomal abnormalities linked to aging and neurodegenerative diseases. While the current evidence suggests that the exosomal system in the brain can be modulated both by membrane lipid composition and the expression of key proteins that contribute to the formation and secretion of exosomes, how exosomal pathway-regulatory elements sense and respond to perturbations in the endosomal pathway is not well understood. Based upon findings from the extensively studied DS and APOE4 models, we propose that enhanced neuronal exosome secretion can be a protective response, reducing pathological disruption of the endosomal–lysosomal system in disease-vulnerable neurons. Developing therapeutic approaches that help to maintain or enhance neuronal exosome biogenesis and release may be beneficial in a range of disorders of the central nervous system. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
20. Exosome Production Is Key to Neuronal Endosomal Pathway Integrity in Neurodegenerative Diseases.
- Author
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Mathews, Paul M. and Levy, Efrat
- Subjects
NEURODEGENERATION ,CENTRAL nervous system ,PROTEIN precursors ,APOLIPOPROTEIN E ,MEMBRANE lipids ,BLOOD-brain barrier - Abstract
Dysfunction of the endosomal–lysosomal system is a prominent pathogenic factor in Alzheimer's disease (AD) and other neurodevelopmental and neurodegenerative disorders. We and others have extensively characterized the neuronal endosomal pathway pathology that results from either triplication of the amyloid-β precursor protein (APP) gene in Down syndrome (DS) or from expression of the apolipoprotein E ε4 allele (APOE4), the greatest genetic risk factor for late-onset AD. More recently brain exosomes, extracellular vesicles that are generated within and released from endosomal compartments, have been shown to be altered in DS and by APOE4 expression. In this review, we discuss the emerging data arguing for an interdependence between exosome production and endosomal pathway integrity in the brain. In vitro and in vivo studies indicate that altered trafficking through the endosomal pathway or compromised cargo turnover within lysosomes can affect the production, secretion, and content of exosomes. Conversely, exosome biogenesis can affect the endosomal–lysosomal system. Indeed, we propose that efficient exosome release helps to modulate flux through the neuronal endosomal pathway by decompressing potential "traffic jams." Exosome secretion may have the added benefit of unburdening the neuron's lysosomal system by delivering endosomal–lysosomal material into the extracellular space, where other cell types may contribute to the degradation of neuronal debris. Thus, maintaining robust neuronal exosome production may prevent or mitigate endosomal and lysosomal abnormalities linked to aging and neurodegenerative diseases. While the current evidence suggests that the exosomal system in the brain can be modulated both by membrane lipid composition and the expression of key proteins that contribute to the formation and secretion of exosomes, how exosomal pathway-regulatory elements sense and respond to perturbations in the endosomal pathway is not well understood. Based upon findings from the extensively studied DS and APOE4 models, we propose that enhanced neuronal exosome secretion can be a protective response, reducing pathological disruption of the endosomal–lysosomal system in disease-vulnerable neurons. Developing therapeutic approaches that help to maintain or enhance neuronal exosome biogenesis and release may be beneficial in a range of disorders of the central nervous system. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
21. Inhibition of nSMase2 Reduces the Transfer of Oligomeric α-Synuclein Irrespective of Hypoxia.
- Author
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Sackmann, Valerie, Sinha, Maitrayee Sardar, Sackmann, Christopher, Civitelli, Livia, Bergström, Joakim, Ansell-Schultz, Anna, and Hallbeck, Martin
- Subjects
PARKINSON'S disease ,HYPOXEMIA ,OXIDATIVE stress ,SPHINGOLIPIDS ,NEURODEGENERATION - Abstract
Recently, extracellular vesicles (EVs), such as exosomes, have been proposed to play an influential role in the cell-to-cell spread of neurodegenerative diseases, including the intercellular transmission of α-synuclein (α-syn). However, the regulation of EV biogenesis and its relation to Parkinson's disease (PD) is only partially understood. The generation of EVs through the ESCRT-independent pathway depends on the hydrolysis of sphingomyelin by neutral sphingomyelinase 2 (nSMase2) to produce ceramide, which causes the membrane of endosomal multivesicular bodies to bud inward. nSMase2 is sensitive to oxidative stress, a common process in PD brains; however, little is known about the role of sphingomyelin metabolism in the pathogenesis of PD. This is the first study to show that inhibiting nSMase2 decreases the transfer of oligomeric aggregates of α-syn between neuron-like cells. Furthermore, it reduced the accumulation and aggregation of high-molecular-weight α-syn. Hypoxia, as a model of oxidative stress, reduced the levels of nSMase2, but not its enzymatic activity, and significantly altered the lipid composition of cells without affecting EV abundance or the transfer of α-syn. These data show that altering sphingolipids can mitigate the spread of α-syn, even under hypoxic conditions, potentially suppressing PD progression. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
22. Prion-Like Mechanisms in Parkinson's Disease.
- Author
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Ma, Jiangnan, Gao, Jing, Wang, Jing, and Xie, Anmu
- Subjects
PARKINSON'S disease ,PRION diseases ,AMYOTROPHIC lateral sclerosis ,ALZHEIMER'S disease ,CENTRAL nervous system - Abstract
Formation and aggregation of misfolded proteins in the central nervous system (CNS) is a key hallmark of several age-related neurodegenerative diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). These diseases share key biophysical and biochemical characteristics with prion diseases. It is believed that PD is characterized by abnormal protein aggregation, mainly that of α-synuclein (α-syn). Of particular importance, there is growing evidence indicating that abnormal α-syn can spread to neighboring brain regions and cause aggregation of endogenous α-syn in these regions as seeds, in a "prion-like" manner. Abundant studies in vitro and in vivo have shown that α-syn goes through a templated conformational change, propagates from the original region to neighboring regions, and eventually cause neuron degeneration in the substantia nigra and striatum. The objective of this review is to summarize the mechanisms involved in the aggregation of abnormal intracellular α-syn and its subsequent cell-to-cell transmission. According to these findings, we look forward to effective therapeutic perspectives that can block the progression of neurodegenerative diseases. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
23. Increased DJ-1 and α-Synuclein in Plasma Neural-Derived Exosomes as Potential Markers for Parkinson's Disease.
- Author
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Zhao, Zhen-Hua, Chen, Zhi-Ting, Zhou, Rui-Ling, Zhang, Xu, Ye, Qin-Yong, and Wang, Yin-Zhou
- Subjects
ALPHA-synuclein ,EXOSOMES ,PARKINSON'S disease ,CEREBROSPINAL fluid ,BLOOD plasma ,BIOLOGICAL tags - Abstract
The diagnosis of PD might be in difficulty, especially in the early stages. Therefore, the identification of novel biomarkers is imperative for the diagnosis and monitoring disease progression in PD. DJ-1 and α-synuclein, are two proteins that are critically involved in the pathogenesis of PD, and they have been examined as disease biomarkers in studies. However, no study exists regarding DJ-1 in plasma neural-derived exosomes. In the present study, the levels of DJ-1 and α-synuclein in plasma neural-derived exosomes were studied together in order to investigate novel biomarkers for PD. DJ-1 and α-synuclein in plasma and plasma neural-derived exosomes of the patients with PD and controls were quantified by ELISAs. The data revealed that the levels of DJ-1 and α-synuclein in plasma neural-derived exosomes and the ratio of plasma neural-derived exosomal DJ-1 to total DJ-1 were significantly higher in patients with PD, compared with controls, while levels of the two proteins in plasma exhibited no difference between the patients with PD and controls. However, no relationship was identified between biomarkers and disease progression. In addition, significant positive correlations between DJ-1 and α-synuclein in plasma neural-derived exosomes were found in the patients with PD and in healthy individuals. We hypothesize that DJ-1 in plasma neural-derived exosomes may be used as a potential biomarker as α-synuclein in PD and they might participate in the mechanism of PD together. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
24. Disturbed Experience of Time in Depression--Evidence from Content Analysis.
- Author
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Vogel, David H. V., Krämer, Katharina, Schoofs, Theresa, Kupke, Christian, and Vogeley, Kai
- Subjects
MENTAL depression ,PHILOSOPHY of time ,CONTENT analysis ,EXPERIENCE ,TIME perception - Abstract
Disturbances in the experience of time have been a commonly reported feature of depressive disorders since the beginning of modern psychiatry and psychological research. However, qualitative research approaches to investigate the phenomenon are rarely used.We employed content analysis to investigate disturbances of time experience in Major Depressive Disorder. Our analysis from 25 participants showed that individuals with Major Depressive Disorder subjectively seem to have lost the ability to influence or change the present, resulting in an impersonal and blocked future. The present is rendered meaningless, the past unchangeably negative, and the passage of time turned into a dragging, inexorable, and viscous continuance. The overall,--possibly intersubjective-concept of time experience, remains largely intact, causing or adding to depressive mood and suffering. We elaborate on how these findings reflect previous theories on the experience of time in depression. This study might encourage future inquiries into both the phenomenal and neuroscientific foundation of time experience under psychopathological conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
25. Motor Timing and Covariation with Time Perception: Investigating the Role of Handedness.
- Author
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O'Regan, Louise, Spapé, Michiel M., and Serrien, Deborah J.
- Subjects
TIME perception ,HANDEDNESS ,COGNITION ,HUMAN behavior ,MOTOR neurons - Abstract
Time is a fundamental dimension of our behavior and enables us to guide our actions and to experience time such as predicting collisions or listening to music. In this study, we investigate the regulation and covariation of motor timing and time perception functions in left- and right-handers who are characterized by distinct brain processing mechanisms for cognitive-motor control. To this purpose, we use a combination of tasks that assess the timed responses during movements and the perception of time intervals. The results showed a positive association across left- and right-handers between movement-driven timing and perceived interval duration when adopting a preferred tempo, suggesting cross-domain coupling between both abilities when an intrinsic timescale is present. Handedness guided motor timing during externally-driven conditions that required cognitive intervention, which specifies the relevance of action expertise for the performance of timed-based motor activities. Overall, our results reveal that individual variation across domain-general and domain-specific levels of organization plays a steering role in how one predicts, perceives and experiences time, which accordingly impacts on cognition and behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
26. Passage of Time Judgments Are Not Duration Judgments: Evidence from a Study Using Experience Sampling Methodology.
- Author
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Droit-Volet, Sylvie, Wearden, John, Janssen, Steve M. J., and Ernst, Benjamin
- Subjects
TIME perception ,INDIVIDUAL differences ,JUDGMENT (Psychology) ,GERIATRIC psychology ,EVERYDAY life - Abstract
This study examined relations between passage of time judgments and duration judgments (DJs) in everyday life, in young and elderly people, with an Experience Sampling Method. The DJs were assessed by verbal estimation and interval production measures. The results showed no difference between young and elderly people in judgments of rate of passage of time, a result contrary to the conventional idea that time passes more quickly as we get older. There were also no significant relation between the judgment of passage of time and the judgments of durations. In addition, the significant predictors of individual differences in the judgment of passage of time (emotion states and focus of attention on the current activity) were not predictors of judgment of durations. In sum, passages of time judgments are not related to DJs. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
27. Subjective expansion of extended time-spans in experienced meditators.
- Author
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Wittmann, Marc, Otten, Simone, Schötz, Eva, Sarikaya, Anna, Lehnen, Hanna, Han-Gue Jo, Kohls, Niko, Schmidt, Stefan, and Meissner, Karin
- Abstract
Experienced meditators typically report that they experience time slowing down in meditation practice as well as in everyday life. Conceptually this phenomenon may be understood through functional states of mindfulness, i.e., by attention regulation, body awareness, emotion regulation, and enhanced memory. However, hardly any systematic empirical work exists regarding the experience of time in meditators. In the current cross-sectional study, we investigated whether 42 experienced mindfulness meditation practitioners (with on average 10 years of experience) showed differences in the experience of time as compared to 42 controls without any meditation experience matched for age, sex, and education. The perception of time was assessed with a battery of psychophysical tasks assessing the accuracy of prospective time judgments in duration discrimination, duration reproduction, and time estimation in the milliseconds to minutes range as well with several psychometric instruments related to subjective time such as the ZimbardoTime Perspective Inventory, the Barratt Impulsivity Scale and the Freiburg Mindfulness Inventory. In addition, subjective time judgments on the current passage of time and retrospective time ranges were assessed. While subjective judgements of time were found to be significantly different between the two groups on several scales, no differences in duration estimates in the psychophysical tasks were detected. Regarding subjective time, mindfulness meditators experienced less time pressure, more time dilation, and a general slower passage of time. Moreover, they felt that the last week and the last month passed more slowly. Overall, although no intergroup differences in psychophysical tasks were detected, the reported findings demonstrate a close association between mindfulness meditation and the subjective feeling of the passage of time captured by psychometric instruments. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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