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Sleep Medicine Sep 2021A growing body of evidence suggests that sleep and Alzheimer's disease (AD) have a bi-directional relationship. Emerging research also suggests that orexin, a key... (Meta-Analysis)
Meta-Analysis
OBJECTIVE/BACKGROUND
A growing body of evidence suggests that sleep and Alzheimer's disease (AD) have a bi-directional relationship. Emerging research also suggests that orexin, a key neurotransmitter involved in sleep-wake regulation, may be altered in persons with AD, however results have not been consistent across prior studies. This investigation was conducted to both evaluate the aggregate literature to minimize the risk of bias and identify potential factors associated with heterogeneity across studies.
METHODS
Systematic review identified relevant investigations that compared cerebrospinal fluid orexin in persons with AD and controls. Meta-analysis (random effects model) compared effect size (Hedge's g) for orexin between AD and controls. Meta-regression was additionally performed for key variables of interest to evaluate potential causes of heterogeneity among studies.
RESULTS
17 studies were identified that met inclusion/exclusion criteria. Evidence of publication bias was not identified. Non-significant increases in orexin were observed in AD relative to controls, with moderate to large heterogeneity among studies (Hedge's g = 0.20, p = 0.136, I = 72.6%). Meta-regression demonstrated both year of publication (β = 0.055, p = 0.020) and effect size for phosphorylated tau in AD versus controls (β = 0.417, p = 0.031) were associated with differences in orexin.
CONCLUSIONS
Results do not support broad differences in orexin in AD compared to controls, however, evolving diagnostic criteria may have affected findings across studies. Future research that examines orexin in AD over the longitudinal course of the disorder and explores potential links between phosphorylated tau and orexin are indicated.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Humans; Orexins; Sleep; Sleep Wake Disorders; tau Proteins
PubMed: 34364094
DOI: 10.1016/j.sleep.2021.07.007 -
Biomolecules Jul 2021Alzheimer's disease (AD), a progressive neurodegenerative disease, affects approximately 50 million people worldwide, which warrants the search for reliable new... (Meta-Analysis)
Meta-Analysis
Alzheimer's disease (AD), a progressive neurodegenerative disease, affects approximately 50 million people worldwide, which warrants the search for reliable new biomarkers for early diagnosis of AD. Brain-derived exosomal (BDE) proteins, which are extracellular nanovesicles released by all cell lineages of the central nervous system, have been focused as biomarkers for diagnosis, screening, prognosis prediction, and monitoring in AD. This review focused on the possibility of BDE proteins as AD biomarkers. The articles published prior to 26 January 2021 were searched in PubMed, EMBASE, Web of Science, and Cochrane Library to identify all relevant studies that reported exosome biomarkers in blood samples of patients with AD. From 342 articles, 20 studies were selected for analysis. We conducted a meta-analysis of six BDE proteins and found that levels of amyloid-β42 (standardized mean difference (SMD) = 1.534, 95% confidence interval [CI]: 0.595-2.474), total-tau (SMD = 1.224, 95% CI: 0.534-1.915), tau phosphorylated at threonine 181 (SMD = 4.038, 95% CI: 2.312-5.764), and tau phosphorylated at serine 396 (SMD = 2.511, 95% CI: 0.795-4.227) were significantly different in patients with AD compared to those in control. Whereas, those of p-tyrosine-insulin receptor substrate-1 and heat shock protein 70 did not show significant differences. This review suggested that Aβ42, t-tau, p-T181-tau, and p-S396-tau could be effective in diagnosing AD as blood biomarkers, despite the limitation in the meta-analysis based on the availability of data. Therefore, certain BDE proteins could be used as effective biomarkers for AD.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Brain; Exosomes; HSP70 Heat-Shock Proteins; Humans; Insulin Receptor Substrate Proteins; Peptide Fragments; tau Proteins
PubMed: 34356604
DOI: 10.3390/biom11070980 -
Frontiers in Cardiovascular Medicine 2021Atrial fibrillation (AF) is associated with calcium (Ca) handling remodeling and increased spontaneous calcium release events (SCaEs). Nevertheless, its exact mechanism...
Atrial fibrillation (AF) is associated with calcium (Ca) handling remodeling and increased spontaneous calcium release events (SCaEs). Nevertheless, its exact mechanism remains unclear, resulting in suboptimal primary and secondary preventative strategies. We searched the PubMed database for studies that investigated the relationship between SCaEs and AF and/or its risk factors. Meta-analysis was used to examine the Ca mechanisms involved in the primary and secondary AF preventative groups. We included a total of 74 studies, out of the identified 446 publications from inception (1982) until March 31, 2020. Forty-five were primary and 29 were secondary prevention studies for AF. The main Ca release events, calcium transient (standardized mean difference (SMD) = 0.49; = 35%; confidence interval (CI) = 0.33-0.66; < 0.0001), and spark amplitude (SMD = 0.48; = 0%; CI = -0.98-1.93; = 0.054) were enhanced in the primary diseased group, while calcium transient frequency was increased in the secondary group. Calcium spark frequency was elevated in both the primary diseased and secondary AF groups. One of the key cardiac currents, the L-type calcium current (I) was significantly downregulated in primary diseased (SMD = -1.07; = 88%; CI = -1.94 to -0.20; < 0.0001) and secondary AF groups (SMD = -1.28; = 91%; CI = -2.04 to -0.52; < 0.0001). Furthermore, the sodium-calcium exchanger (I) and NCX1 protein expression were significantly enhanced in the primary diseased group, while only NCX1 protein expression was shown to increase in the secondary AF studies. The phosphorylation of the ryanodine receptor at S2808 (pRyR-S2808) was significantly elevated in both the primary and secondary groups. It was increased in the primary diseased and proarrhythmic subgroups (SMD = 0.95; = 64%; CI = 0.12-1.79; = 0.074) and secondary AF group (SMD = 0.66; = 63%; CI = 0.01-1.31; < 0.0001). Sarco/endoplasmic reticulum Ca-ATPase (SERCA) expression was elevated in the primary diseased and proarrhythmic drug subgroups but substantially reduced in the secondary paroxysmal AF subgroup. Our study identified that I is reduced in both the primary and secondary diseased groups. Furthermore, pRyR-S2808 and NCX1 protein expression are enhanced. The remodeling leads to elevated Ca functional activities, such as increased frequencies or amplitude of Ca spark and Ca transient. The main difference identified between the primary and secondary diseased groups is SERCA expression, which is elevated in the primary diseased group and substantially reduced in the secondary paroxysmal AF subgroup. We believe our study will add new evidence to AF mechanisms and treatment targets.
PubMed: 34355025
DOI: 10.3389/fcvm.2021.662914 -
Journal of Neuromuscular Diseases 2021Leigh syndrome (LS) is the most frequent paediatric clinical presentation of mitochondrial disease. The clinical phenotype of LS is highly heterogeneous. Though...
BACKGROUND
Leigh syndrome (LS) is the most frequent paediatric clinical presentation of mitochondrial disease. The clinical phenotype of LS is highly heterogeneous. Though historically the treatment for LS is largely supportive, new treatments are on the horizon. Due to the rarity of LS, large-scale interventional studies are scarce, limiting dissemination of information of therapeutic options to the wider scientific and clinical community.
OBJECTIVE
We conducted a systematic review of pharmacological therapies of LS following the guidelines for FAIR-compliant datasets.
METHODS
We searched for interventional studies within Clincialtrials.gov and European Clinical trials databases. Randomised controlled trials, observational studies, case reports and case series formed part of a wider MEDLINE search.
RESULTS
Of the 1,193 studies initially identified, 157 met our inclusion criteria, of which 104 were carried over into our final analysis. Treatments for LS included very few interventional trials using EPI-743 and cysteamine bitartrate. Wider literature searches identified case series and reports of treatments repleting glutathione stores, reduction of oxidative stress and restoration of oxidative phosphorylation.
CONCLUSIONS
Though interventional randomised controlled trials have begun for LS, the majority of evidence remains in case reports and case series for a number of treatable genes, encoding cofactors or transporter proteins of the mitochondria. Our findings will form part of the international expert-led Solve-RD efforts to assist clinicians initiating treatments in patients with treatable variants of LS.
Topics: Child; Humans; Leigh Disease; Mitochondria; Phenotype
PubMed: 34308912
DOI: 10.3233/JND-210715 -
Translational Neurodegeneration Mar 2021A lack of convenient and reliable biomarkers for diagnosis and prognosis is a common challenge for neurodegenerative diseases such as Alzheimer's disease (AD). Recent... (Meta-Analysis)
Meta-Analysis
A lack of convenient and reliable biomarkers for diagnosis and prognosis is a common challenge for neurodegenerative diseases such as Alzheimer's disease (AD). Recent advancement in ultrasensitive protein assays has allowed the quantification of tau and phosphorylated tau proteins in peripheral plasma. Here we identified 66 eligible studies reporting quantification of plasma tau and phosphorylated tau 181 (ptau181) using four ultrasensitive methods. Meta-analysis of these studies confirmed that the AD patients had significantly higher plasma tau and ptau181 levels compared with controls, and that the plasma tau and ptau181 could predict AD with high-accuracy area under curve of the Receiver Operating Characteristic. Therefore, plasma tau and plasma ptau181 can be considered as biomarkers for AD diagnosis.
Topics: Alzheimer Disease; Biomarkers; Humans; Phosphorylation; Reproducibility of Results; tau Proteins
PubMed: 33712071
DOI: 10.1186/s40035-021-00234-5 -
Frontiers in Oncology 2020Cancer is one of the main causes of human death worldwide. Recently, many studies have firmly established the causal relationship between oxidative stress and cancer...
Cancer is one of the main causes of human death worldwide. Recently, many studies have firmly established the causal relationship between oxidative stress and cancer initiation and progression. As a key protein in PI3K/Akt signaling pathway, p-AKT (phosphorylated Akt) participates in the process of oxidative stress and plays a prognostic role in various hematologic tumors and solid tumors. We conducted a comprehensive search of the PubMed, Embase and Cochrane libraries to identify studies published in the past decade involving cancer patients expressing p-AKT that reported overall survival (OS) during follow-up. In this study, 6,128 patients in total were evaluated from 29 enrolled articles, and we concluded that overexpression of p-AKT was closely related to worse OS in cancer patients with a hazard ratio (HR) of 2.33 (95% CI: 1.67-4.00). Furthermore, we conducted a subgroup analysis, and the results indicated that overexpression of p-AKT was associated with worse OS in hematological tumor (HR: 1.64, 95% CI: 1.41-1.92), and solid tumor (HR: 2.44, 95% CI: 1.61-5.26). High expression of p-AKT is related to poor prognosis of various hematologic tumors and solid tumors.
PubMed: 33363017
DOI: 10.3389/fonc.2020.588200 -
Neurobiology of Disease Feb 2021Neurodegenerative disorders such as Alzheimer's disease (AD), Lewy body diseases (LBD), and the amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD)... (Meta-Analysis)
Meta-Analysis
Neurodegenerative disorders such as Alzheimer's disease (AD), Lewy body diseases (LBD), and the amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD) spectrum are defined by the accumulation of specific misfolded protein aggregates. However, the mechanisms by which each proteinopathy leads to neurodegeneration remain elusive. We hypothesized that there is a common "pan-neurodegenerative" gene expression signature driving pathophysiology across these clinically and pathologically diverse proteinopathies. To test this hypothesis, we performed a systematic review of human CNS transcriptomics datasets from AD, LBD, and ALS-FTD patients and age-matched controls in the Gene Expression Omnibus (GEO) and ArrayExpress databases, followed by consistent processing of each dataset, meta-analysis, pathway enrichment, and overlap analyses. After applying pre-specified eligibility criteria and stringent data pre-processing, a total of 2600 samples from 26 AD, 21 LBD, and 13 ALS-FTD datasets were included in the meta-analysis. The pan-neurodegenerative gene signature is characterized by an upregulation of innate immunity, cytoskeleton, and transcription and RNA processing genes, and a downregulation of the mitochondrial electron transport chain. Pathway enrichment analyses also revealed the upregulation of neuroinflammation (including Toll-like receptor, TNF, and NFκB signaling) and phagocytosis, and the downregulation of mitochondrial oxidative phosphorylation, lysosomal acidification, and ubiquitin-proteasome pathways. Our findings suggest that neuroinflammation and a failure in both neuronal energy metabolism and protein degradation systems are consistent features underlying neurodegenerative diseases, despite differences in the extent of neuronal loss and brain regions involved.
Topics: Alzheimer Disease; Amyotrophic Lateral Sclerosis; Brain; Energy Metabolism; Frontotemporal Dementia; Humans; Inflammation; Inflammation Mediators; Lewy Body Disease; Neurodegenerative Diseases; Proteostasis; Transcriptome
PubMed: 33347974
DOI: 10.1016/j.nbd.2020.105225 -
Frontiers in Physiology 2020Endogenous circadian rhythms are biological processes generated by an internal body clock. They are self-sustaining, and they govern biochemical and physiological...
Endogenous circadian rhythms are biological processes generated by an internal body clock. They are self-sustaining, and they govern biochemical and physiological processes. However, circadian rhythms are influenced by many external stimuli to reprogram the phase in response to environmental change. Through their adaptability to environmental changes, they synchronize physiological responses to environmental challenges that occur within a sidereal day. The precision of this circadian system is assured by many post-translational modifications (PTMs) that occur on the protein components of the circadian clock mechanism. The most ancient example of circadian rhythmicity driven by phosphorylation of clock proteins was observed in cyanobacteria. The influence of phosphorylation on the circadian system is observed through different kingdoms, from plants to humans. Here, we discuss how phosphorylation modulates the mammalian circadian clock, and we give a detailed overview of the most critical discoveries in the field.
PubMed: 33324245
DOI: 10.3389/fphys.2020.612510 -
MSystems Dec 2020The spread of carbapenem- and polymyxin-resistant poses a significant threat to public health, challenging clinicians worldwide with limited therapeutic options. This... (Review)
Review
The spread of carbapenem- and polymyxin-resistant poses a significant threat to public health, challenging clinicians worldwide with limited therapeutic options. This review describes the current coding and noncoding genetic and transcriptional mechanisms mediating carbapenem and polymyxin resistance, respectively. A systematic review of all studies published in PubMed database between 2015 to October 2020 was performed. Journal articles evaluating carbapenem and polymyxin resistance mechanisms, respectively, were included. The search identified 171 journal articles for inclusion. Different New Delhi metallo-β-lactamase (NDM) carbapenemase variants had different transcriptional and affinity responses to different carbapenems. Mutations within the carbapenemase (KPC) mobile transposon, Tn, affect its promoter activity and expression levels, increasing carbapenem resistance. Insertion of IS in increased imipenemase expression 53-fold. porin downregulation (mediated by and mutations), small RNA hyperexpression, efflux upregulation (mediated by , , , , , , etc.), and mutations in - mediated clinical carbapenem resistance when coupled with β-lactamase activity in a species-specific manner but not when acting without β-lactamases. Mutations in , , , and affect phosphorylation of lipid A of the lipopolysaccharide through the ( or ) cluster, leading to polymyxin resistance; inactivation also affected capsule structure. Mobile and induced , efflux hyperexpression and porin downregulation, and Ecr transmembrane protein also conferred polymyxin resistance and heteroresistance. Carbapenem and polymyxin resistance is thus mediated by a diverse range of genetic and transcriptional mechanisms that are easily activated in an inducing environment. The molecular understanding of these emerging mechanisms can aid in developing new therapeutics for multidrug-resistant isolates.
PubMed: 33323413
DOI: 10.1128/mSystems.00783-20 -
In Vivo (Athens, Greece) 2020The insulin-like growth factor bioregulation system is implicated in cancer biology. Herein, we aim to review the evidence on the expression of the insulin-like growth... (Review)
Review
BACKGROUND/AIM
The insulin-like growth factor bioregulation system is implicated in cancer biology. Herein, we aim to review the evidence on the expression of the insulin-like growth factor 1 and 2 (IGF1 and IGF2), their receptors (IGF-Rs) and IGF-binding proteins (IGFBPs) in thyroid tissue and their possible association with benign and malignant thyroid nodular diseases.
MATERIALS AND METHODS
We systematically reviewed Pubmed and Scopus databases up to May 2020. A total of 375 articles were retrieved and analyzed.
RESULTS
Among 375 articles, 45 were included in this systematic review study. IGF1 was investigated in 31 studies, IGF2 in 1, IGF1 receptor in 15 and IGF-binding proteins in 13 articles. IGF1 expression in humans was dependent on the number and compound of benign nodules as well as the method of measurement. In differentiated thyroid carcinoma, a positive correlation between IGF1 and immunohistological stage was documented in some studies while in others only a positive trend was observed. IGF-1R and IGFBPs expression was higher in malignant rather than benign lesions. There was only a positive trend for increased IGF2 expression in malignancy, while IGFBPs were in most studies statistically increased in various cancer types compared to benign nodular disease.
CONCLUSION
The present data demonstrate that in most studies there is statistically positive expression of IGF-1 and less of IGF-2 in thyroid cancer compared to normal thyroid tissue.
Topics: Humans; Insulin-Like Growth Factor Binding Proteins; Insulin-Like Growth Factor I; Phosphorylation; Receptor, IGF Type 1; Signal Transduction; Thyroid Neoplasms
PubMed: 33144411
DOI: 10.21873/invivo.12141