ABSTRACT
Background: Online psychological interventions have emerged as a treatment alternative because they are accessible, flexible, personalized, and available to large populations. The number of Internet interventions in Latin America is limited, as are Randomized Controlled Trials (RCTs) of their effectiveness and a few studies comparing their effectiveness in multiple countries at the same time. We have developed an online intervention, Well-being Online, which will be available to the public free of charge in 7 countries: Mexico, Ecuador, Peru, Chile, Brazil, Spain, and the Netherlands. We expect a reduction in depression and anxiety symptoms and an increase in well-being of the participants. Methods: A multi-country, randomized controlled trial will be conducted. The intervention is multicomponent (Cognitive Behavioral Therapy, Behavioral Activation Therapy, Mindfulness, Acceptance and Commitment Therapy, and Positive Psychology), with 10 sessions. In each country, eligible participants will be randomized to one of three groups: Enriched Intervention (interactive web design with videos, infographics, text, audio, and forum), Text Intervention (text on the website), and Wait List (control group). Repeated measures will be obtained at 5-time points. Our primary outcomes will be anxiety symptomatology, depressive symptomatology, and mental well-being. MANOVA analysis will be used for our main analysis. Discussion: This protocol describes the design of a randomized trial to evaluate the efficacy of a web-based intervention to reduce anxiety and depression symptomatology and increase subjective well-being. The intervention will be made available in four languages (Spanish, Portuguese, Dutch, and English). Its results will contribute to the evidence of effectiveness in terms of randomized trials and Internet interventions, mainly in Latin America and Europe.
ABSTRACT
BACKGROUND: Alcohol, a widely abused drug, significantly diminishes life quality, causing chronic diseases and psychiatric issues, with severe health, societal, and economic repercussions. Previously, we demonstrated that non-voluntary alcohol consumption increases the opening of Cx43 hemichannels and Panx1 channels in astrocytes from adolescent rats. However, whether ethanol directly affects astroglial hemichannels and, if so, how this impacts the function and survival of astrocytes remains to be elucidated. RESULTS: Clinically relevant concentrations of ethanol boost the opening of Cx43 hemichannels and Panx1 channels in mouse cortical astrocytes, resulting in the release of ATP and glutamate. The activation of these large-pore channels is dependent on Toll-like receptor 4, P2X7 receptors, IL-1ß and TNF-α signaling, p38 mitogen-activated protein kinase, and inducible nitric oxide (NO) synthase. Notably, the ethanol-induced opening of Cx43 hemichannels and Panx1 channels leads to alterations in cytokine secretion, NO production, gliotransmitter release, and astrocyte reactivity, ultimately impacting survival. CONCLUSION: Our study reveals a new mechanism by which ethanol impairs astrocyte function, involving the sequential stimulation of inflammatory pathways that further increase the opening of Cx43 hemichannels and Panx1 channels. We hypothesize that targeting astroglial hemichannels could be a promising pharmacological approach to preserve astrocyte function and synaptic plasticity during the progression of various alcohol use disorders.
Subject(s)
Alcoholism , Connexin 43 , Mice , Rats , Animals , Connexin 43/metabolism , Astrocytes/metabolism , Ethanol/toxicity , Ethanol/metabolism , Alcoholism/metabolism , Cells, Cultured , Connexins/metabolism , Nerve Tissue Proteins/metabolismABSTRACT
Background Alcohol, a widely abused drug, significantly diminishes life quality, causing chronic diseases and psychiatric issues, with severe health, societal, and economic repercussions. Previously, we demonstrated that non-voluntary alcohol consumption increases the opening of Cx43 hemichannels and Panx1 channels in astrocytes from adolescent rats. However, whether ethanol directly affects astroglial hemichannels and, if so, how this impacts the function and survival of astrocytes remains to be elucidated. Results Clinically relevant concentrations of ethanol boost the opening of Cx43 hemichannels and Panx1 channels in mouse cortical astrocytes, resulting in the release of ATP and glutamate. The activation of these large-pore channels is dependent on Toll-like receptor 4, P2X7 receptors, IL-1β and TNF-α signaling, p38 mitogen-activated protein kinase, and inducible nitric oxide (NO) synthase. Notably, the ethanol-induced opening of Cx43 hemichannels and Panx1 channels leads to alterations in cytokine secretion, NO production, gliotransmitter release, and astrocyte reactivity, ultimately impacting survival. Conclusion Our study reveals a new mechanism by which ethanol impairs astrocyte function, involving the sequential stimulation of inflammatory pathways that further increase the opening of Cx43 hemichannels and Panx1 channels. We hypothesize that targeting astroglial hemichannels could be a promising pharmacological approach to preserve astrocyte function and synaptic plasticity during the progression of various alcohol use disorders.
Subject(s)
Optic Atrophy, Hereditary, Leber , Pseudotumor Cerebri , Humans , Optic Atrophy, Hereditary, Leber/complications , Optic Atrophy, Hereditary, Leber/diagnosis , Optic Atrophy, Hereditary, Leber/genetics , Pseudotumor Cerebri/complications , Pseudotumor Cerebri/diagnosis , DNA, Mitochondrial/genetics , MutationABSTRACT
Maternal inflammation during pregnancy causes later-in-life alterations of the offspring's brain structure and function. These abnormalities increase the risk of developing several psychiatric and neurological disorders, including schizophrenia, intellectual disability, bipolar disorder, autism spectrum disorder, microcephaly, and cerebral palsy. Here, we discuss how astrocytes might contribute to postnatal brain dysfunction following maternal inflammation, focusing on the signaling mediated by two families of plasma membrane channels: hemi-channels and pannexons. [Ca2+]i imbalance linked to the opening of astrocytic hemichannels and pannexons could disturb essential functions that sustain astrocytic survival and astrocyte-to-neuron support, including energy and redox homeostasis, uptake of K+ and glutamate, and the delivery of neurotrophic factors and energy-rich metabolites. Both phenomena could make neurons more susceptible to the harmful effect of prenatal inflammation and the experience of a second immune challenge during adulthood. On the other hand, maternal inflammation could cause excitotoxicity by producing the release of high amounts of gliotransmitters via astrocytic hemichannels/pannexons, eliciting further neuronal damage. Understanding how hemichannels and pannexons participate in maternal inflammation-induced brain abnormalities could be critical for developing pharmacological therapies against neurological disorders observed in the offspring.
Subject(s)
Astrocytes/metabolism , Ion Channels/metabolism , Mental Disorders , Pregnancy Complications , Prenatal Exposure Delayed Effects , Astrocytes/pathology , Biological Transport, Active , Female , Humans , Inflammation/metabolism , Inflammation/pathology , Mental Disorders/etiology , Mental Disorders/metabolism , Mental Disorders/pathology , Neurodevelopmental Disorders/etiology , Neurodevelopmental Disorders/metabolism , Neurodevelopmental Disorders/pathology , Pregnancy , Pregnancy Complications/metabolism , Pregnancy Complications/pathology , Prenatal Exposure Delayed Effects/etiology , Prenatal Exposure Delayed Effects/metabolism , Prenatal Exposure Delayed Effects/pathologyABSTRACT
Aquaculture activities in southern Chile demand floating devices to produce electricity powered by diesel generators. It has been recently proposed to replace this fuel with propane. However, little is known about the behaviour and possible environmental impacts of an accidental release of propane underwater. In this study we evaluated the impact of water temperature and salinity on the saturation and further release of propane under controlled laboratory experiments. Results showed that under extreme environmentally relevant scenarios (high and low temperature and salinity), propane saturated the water more quickly. However, while it is important to consider that saturation times can be similar (â¼2 h), the magnitudes of propane dissolved can be different. Experiments showed that cold waters (5 °C) propane is dissolved twice than warm waters (20 °C). Residence time was more affected by water temperature and almost independent of water salinity. Propane may take at least 2 days to be released from waters (around 90% of the initial amount dissolved under laboratory conditions). Additionally, we evaluated the impact on dissolved oxygen displacement and the embryotoxicity of the dissolved fraction by using Zebrafish Embryo Toxicity Assay. Results showed that dissolved oxygen was quickly removed. However, the levels of dissolved oxygen were promptly recovered in the studied systems. We also observed that propane can generate genotoxic effects (3-10% mortality), but after 2 days the system can be almost free of propane and the effects may become much lower. Comparatively with the literature, propane showed to be less toxic than diesel and it is a viable and less environmentally hazardous replacement for diesel.
Subject(s)
Propane , Zebrafish , Animals , Chile , Environment , Propane/toxicity , SalinityABSTRACT
The internalization of multi-cellular tissues is a key morphogenetic process during animal development and organ formation. A good example of this is the initial stages of vertebrate central nervous system formation whereby a transient embryonic structure called the neural plate is able to undergo collective cell rearrangements within the dorsal midline. Despite the fact that defects in neural plate midline internalization may result in a series of severe clinical conditions, such as spina bifida and anencephaly, the biochemical and biomechanical details of this process remain only partially characterized. Here we review the main cellular and molecular mechanisms underlying midline cell and tissue internalization during vertebrate neural tube formation. We discuss the contribution of collective cell mechanisms including convergence and extension, as well as apical constriction facilitating midline neural plate shaping. Furthermore, we summarize recent studies that shed light on how the interplay of signaling pathways and cell biomechanics modulate neural plate internalization. In addition, we discuss how adhesion-dependent cell-cell contact appears to be a critical component during midline cell convergence and surface cell contraction via cell-cell mechanical coupling. We envision that more detailed high-resolution quantitative data at both cell and tissue levels will be required to properly model the mechanisms of vertebrate neural plate internalization with the hope of preventing human neural tube defects.
Subject(s)
Neural Plate , Neural Tube , Vertebrates/embryology , Animals , Morphogenesis , Neural Plate/embryology , Neural Tube/embryology , NeurulationABSTRACT
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
ABSTRACT
Tissue internalisation is a key morphogenetic mechanism by which embryonic tissues generate complex internal organs and a number of studies of epithelia have outlined a general view of tissue internalisation. Here we have used quantitative live imaging and mutant analysis to determine whether similar mechanisms are responsible for internalisation in a tissue that apparently does not have a typical epithelial organisation - the zebrafish neural plate. We found that although zebrafish embryos begin neurulation without a conventional epithelium, medially located neural plate cells adopt strategies typical of epithelia in order to constrict their dorsal surface membrane during cell internalisation. Furthermore, we show that Myosin-II activity is a significant driver of this transient cell remodeling which also depends on Cdh2 (N-cadherin). Abrogation of Cdh2 results in defective Myosin-II distribution, mislocalised internalisation events and defective neural plate morphogenesis. Our work suggests Cdh2 coordinates Myosin-II dependent internalisation of the zebrafish neural plate.
Subject(s)
Cadherins/metabolism , Gene Expression Regulation , Myosin Type II/metabolism , Neural Crest/embryology , Zebrafish Proteins/metabolism , Actins/metabolism , Animals , Animals, Genetically Modified , Body Patterning , Cell Membrane/metabolism , Cell Movement , Epithelium/embryology , Gene Expression Regulation, Developmental , Green Fluorescent Proteins/metabolism , Heterocyclic Compounds, 4 or More Rings/pharmacology , Microscopy, Confocal , Morphogenesis , Myosins/metabolism , Neural Plate/embryology , Oligonucleotides/pharmacology , Prospective Studies , Zebrafish/embryologyABSTRACT
Corynebacterium pseudotuberculosis is an intracellular bacteria and the etiologic agent of caseous lymphadenitis in domestic and wildlife species. We report C. pseudotuberculosis infection in Patagonian huemul ( Hippocamelus bisulcus ) from the Cerro Castillo National Reserve, Region of Aysen, Chile. Subcutaneous abscesses in the abdominal and pectoral regions from two animals were sampled and bacteriologic isolation was performed. In both cases, we isolated a C. pseudotuberculosis strain belonging to the ovine genotype. In addition, one isolate was resistant to ciprofloxacin and streptomycin. We report that H. bisulcus is a susceptible species to this bacterium, which is transmitted by direct or indirect contact with domestic sheep ( Ovis aries ) and which represents a potential conservation threat to populations of H. bisulcus . Additional research and prevention efforts should be addressed.
Subject(s)
Corynebacterium Infections/veterinary , Corynebacterium pseudotuberculosis/isolation & purification , Deer/microbiology , Sheep/microbiology , Animals , Chile , Lymphadenitis , Sheep DiseasesABSTRACT
Using a non-experimental, transverse, co-relational design, we assess the relationship between optimism and quality of life (QoL) in adults aged between 18 and 65 years. Two questionnaires were administered: WHOQOL-BREF, which assessed QoL, and an instrument that assessed trait-state optimism. A total of 1190 subjects from various public and private high schools, institutions and commercial centers in the city of Antofagasta, Chile participated. The mean sample age was 40.0 years and 50.0% of respondents were male. There is a relationship between QoL and state optimism, with males demonstrating a higher QoL. Differences in optimism were observed only in age groups in which younger persons scored less than older persons. The results obtained indicate that there is a partial relationship between QoL and optimism, with state optimism having a significant effect on QoL.
Usando un diseño no experimental, transversal-correlacional, evaluamos la relación entre el optimismo y la calidad de vida (CV) en adultos de edades comprendidas entre 18 y 65 años. Se administraron dos cuestionarios: WHOQOL-BREF, que evaluaron la CV, y un instrumento que evalúa optimismo rasgo-estado. Participaron un total de 1190 sujetos de diversas escuelas secundarias públicas y privadas, instituciones y centros comerciales en la ciudad de Antofagasta, Chile. La edad media fue de 40.0 años y 50.0% de los encuestados eran varones. Existe una relación entre el CV y el optimismo estado, entre los varones demostrando una mayor CV. Se observaron diferencias en optimismo solo en grupos de edad en los que las personas más jóvenes puntuaron menos que las personas mayores. Los resultados obtenidos indican que existe una relación parcial de CV y optimismo, con el optimismo estado teniendo un efecto significativo en la CV.
ABSTRACT
BACKGROUND: During the initial stages zebrafish neurulation, neural plate cells undergo highly coordinated movements before they assemble into a multicellular solid neural rod. We have previously identified that the underlying mesoderm is critical to ensure such coordination and generate correct neural tube organization. However, how intertissue coordination is achieved in vivo during zebrafish neural tube morphogenesis is unknown. RESULTS: In this work, we use quantitative live imaging to study the coordinated movements of neural ectoderm and mesoderm during dorsal tissue convergence. We show the extracellular matrix components laminin and fibronectin that lie between mesoderm and neural plate act to couple the movements of neural plate and mesoderm during early stages of neurulation and to maintain the close apposition of these two tissues. CONCLUSIONS: Our study highlights the importance of the extracellular matrix proteins laminin and libronectin in coupling the movements and spatial proximity of mesoderm and neuroectoderm during the morphogenetic movements of neurulation. Developmental Dynamics 245:580-589, 2016. © 2016 Wiley Periodicals, Inc.
Subject(s)
Extracellular Matrix/physiology , Mesoderm/metabolism , Neural Plate/metabolism , Neurulation , Animals , Embryo, Nonmammalian , Fibronectins/physiology , Laminin/physiology , Morphogenesis , Neural Tube , ZebrafishABSTRACT
BACKGROUND: Intrauterine growth restriction is a condition in which the fetus has a birthweight and/or length <10th percentile for the gestational age. Intrauterine growth restriction can be associated with various causes, among which is low uteroplacental perfusion and chronic hypoxia during gestation. Often, intrauterine growth-restricted fetuses have increased oxidative stress; therefore, agents that decrease oxidative stress and increase utero, placental, and umbilical perfusion have been proposed as a beneficial therapeutic strategy. In this scenario, melatonin acts as an umbilical vasodilator and a potent antioxidant that has not been evaluated in pregnancies under chronic hypoxia that induce fetal growth restriction. However, this neurohormone has been proposed as a pharmacologic therapy for complicated pregnancies. OBJECTIVES: The aim of this study was to determine the effects of prenatal administration of melatonin during the last trimester of pregnancy on the biometry of the growth-restricted lambs because of developmental hypoxia. Further, we aimed to determine melatonin and cortisol levels and oxidative stress markers in plasma of pregnant ewes during the treatment. STUDY DESIGN: High-altitude pregnant sheep received either vehicle (n = 5; 5 mL 1.4% ethanol) or melatonin (n = 7; 10 mg/kg(-1)day(-1) in 5 mL 1.4% ethanol) daily during the last one-third of gestation. Maternal plasma levels of melatonin, cortisol, antioxidant capacity, and oxidative stress were determined along treatment. At birth, neonates were examined, weighed, and measured (biparietal diameter, abdominal diameter, and crown-rump length). RESULTS: Antenatal treatment with melatonin markedly decreased neonatal biometry and weight at birth. Additionally, melatonin treatment increased the length of gestation by 7.5% and shifted the time of delivery. Furthermore, the prenatal treatment doubled plasma levels of melatonin and cortisol and significantly improved the antioxidant capacity of the pregnant ewes. CONCLUSIONS: Our findings indicate that antenatal melatonin induces further intrauterine growth restriction but improves the maternal plasma antioxidant capacity. Additional studies should address the efficiency and safety of antenatal melatonin before clinical attempts on humans.
Subject(s)
Birth Weight/drug effects , Fetal Development/drug effects , Fetal Growth Retardation/drug therapy , Melatonin/adverse effects , Oxidative Stress/drug effects , Animals , Biomarkers/blood , Female , Fetal Growth Retardation/chemically induced , Gestational Age , Hydrocortisone/blood , Melatonin/blood , Melatonin/pharmacology , Melatonin/therapeutic use , Oxidative Stress/physiology , Pregnancy , Pregnancy Outcome , SheepABSTRACT
The development of a vertebrate neural epithelium with well-organized apico-basal polarity and a central lumen is essential for its proper function. However, how this polarity is established during embryonic development and the potential influence of surrounding signals and tissues on such organization has remained less understood. In recent years the combined superior transparency and genetics of the zebrafish embryo has allowed for in vivo visualization and quantification of the cellular and molecular dynamics that govern neural tube structure. Here, we discuss recent studies revealing how co-ordinated cell-cell interactions coupled with adjacent tissue dynamics are critical to regulate final neural tissue architecture. Furthermore, new findings show how the spatial regulation and timing of orientated cell division is key in defining precise lumen formation at the tissue midline. In addition, we compare zebrafish neurulation with that of amniotes and amphibians in an attempt to understand the conserved cellular mechanisms driving neurulation and resolve the apparent differences among animals. Zebrafish neurulation not only offers fundamental insights into early vertebrate brain development but also the opportunity to explore in vivo cell and tissue dynamics during complex three-dimensional animal morphogenesis.
Subject(s)
Embryo, Nonmammalian/embryology , Neural Tube/embryology , Neurulation/physiology , Zebrafish/embryology , AnimalsABSTRACT
BACKGROUND: Morphogenesis of the zebrafish neural tube requires the coordinated movement of many cells in both time and space. A good example of this is the movement of the cells in the zebrafish neural plate as they converge towards the dorsal midline before internalizing to form a neural keel. How these cells are regulated to ensure that they move together as a coherent tissue is unknown. Previous work in other systems has suggested that the underlying mesoderm may play a role in this process but this has not been shown directly in vivo. RESULTS: Here we analyze the roles of subjacent mesoderm in the coordination of neural cell movements during convergence of the zebrafish neural plate and neural keel formation. Live imaging demonstrates that the normal highly coordinated movements of neural plate cells are lost in the absence of underlying mesoderm and the movements of internalization and neural tube formation are severely disrupted. Despite this, neuroepithelial polarity develops in the abnormal neural primordium but the resulting tissue architecture is very disorganized. CONCLUSIONS: We show that the movements of cells in the zebrafish neural plate are highly coordinated during the convergence and internalization movements of neurulation. Our results demonstrate that the underlying mesoderm is required for these coordinated cell movements in the zebrafish neural plate in vivo.
Subject(s)
Cell Movement , Mesoderm/embryology , Neural Plate/embryology , Neural Tube/embryology , Zebrafish/embryology , Animals , Body Patterning , Nodal Signaling Ligands/metabolismABSTRACT
BACKGROUND: Morphogenesis requires developmental processes to occur both at the right time and in the right place. During neural tube formation in the zebrafish embryo, the generation of the apical specializations of the lumen must occur in the center of the neural rod after the neural cells have undergone convergence, invagination and interdigitation across the midline. How this coordination is achieved is uncertain. One possibility is that environmental signaling at the midline of the neural rod controls the schedule of apical polarization. Alternatively, polarization could be regulated by a timing mechanism and then independent morphogenetic processes ensure the cells are in the correct spatial location. RESULTS: Ectopic transplantation demonstrates the local environment of the neural midline is not required for neural cell polarization. Neural cells can self-organize into epithelial cysts in ectopic locations in the embryo and also in three-dimensional gel cultures. Heterochronic transplants demonstrate that the schedule of polarization and the specialized cell divisions characteristic of the neural rod are more strongly regulated by time than local environmental signals. The cells' schedule for polarization is set prior to gastrulation, is stable through several rounds of cell division and appears independent of the morphogenetic movements of gastrulation and neurulation. CONCLUSIONS: Time rather than local environment regulates the schedule of epithelial polarization in zebrafish neural rod.
Subject(s)
Body Patterning/physiology , Neural Stem Cells/cytology , Neural Tube/embryology , Neurogenesis/physiology , Zebrafish/embryology , Animals , Immunohistochemistry , Microscopy, ConfocalABSTRACT
By analysing the cellular and subcellular events that occur in the centre of the developing zebrafish neural rod, we have uncovered a novel mechanism of cell polarisation during lumen formation. Cells from each side of the neural rod interdigitate across the tissue midline. This is necessary for localisation of apical junctional proteins to the region where cells intersect the tissue midline. Cells assemble a mirror-symmetric microtubule cytoskeleton around the tissue midline, which is necessary for the trafficking of proteins required for normal lumen formation, such as partitioning defective 3 and Rab11a to this point. This occurs in advance and is independent of the midline cell division that has been shown to have a powerful role in lumen organisation. To our knowledge, this is the first example of the initiation of apical polarisation part way along the length of a cell, rather than at a cell extremity. Although the midline division is not necessary for apical polarisation, it confers a morphogenetic advantage by efficiently eliminating cellular processes that would otherwise bridge the developing lumen.
Subject(s)
Cell Communication , Microtubules/metabolism , Neural Tube/embryology , Neurulation , Zebrafish Proteins/metabolism , Zebrafish/embryology , Animals , Body Patterning , Carrier Proteins/genetics , Carrier Proteins/metabolism , Cell Division , Cell Movement , Cell Polarity , Embryo, Nonmammalian/cytology , Embryo, Nonmammalian/embryology , Green Fluorescent Proteins/chemistry , Luminescent Agents/chemistry , Microtubules/genetics , Mutation , Neural Tube/cytology , Nocodazole/pharmacology , Protein Transport/drug effects , Recombinant Fusion Proteins , Tubulin Modulators/pharmacology , Zebrafish/anatomy & histology , Zebrafish/genetics , Zebrafish/metabolism , Zebrafish Proteins/genetics , rab GTP-Binding Proteins/genetics , rab GTP-Binding Proteins/metabolismABSTRACT
Polystyrene grafted with a chiral zinc-complexing camphor-derived N,N-disubstituted hydroxyamide is proposed as a new type of functional polymer of high reusability for the development of sustainable organozinc-catalyzed asymmetric reactions. The main goal of this new functional polymer is the ease of the hydroxyamide-moiety preparation (cheap chiral ligand obtained straightforwardly from an enantiopure starting material coming from the chiral pool), as well as its chemical robustness when compared with other related zinc-complexing functional groups. The latter allows the polymer to be active after multiple applications, without significant loss of its catalytic activity. This fact is exemplified by the design and preparation of a polymer functionalized with a bis(hydroxyamide) proved previously as active in the homogeneous enantioselective addition of diethylzinc to aldehydes. The result is a cheap functional polymer with a very high reusability (the enantioselectivity and chemical yield are maintained practically constant after 20 applications). Additionally, a methodology for the multicycle use of these functional polymers is presented.
ABSTRACT
Cerebral blood flow (CBF) is normally controlled by myogenic and metabolic mechanisms that can be impaired in different cerebrovascular conditions. Modeling the influences of arterial blood pressure (ABP) and arterial CO(2) (PaCO(2)) on CBF is an essential step to shed light on regulatory mechanisms and extract clinically relevant parameters. Support Vector Machines (SVM) were used to model the influences of ABP and PaCO(2) on CBFV in two different conditions: baseline and during breathing of 5% CO(2) in air, in a group of 16 healthy subjects. Different model structures were considered, including innovative non-linear multivariate autoregressive (AR) models. Results showed that AR models are significantly superior to finite impulse response models and that non-linear models provide better performance for both structures. Correlation coefficients for multivariate AR non-linear models were 0.71 ± 0.11 at baseline, reaching 0.91 ± 0.06 during 5% CO(2). These results warrant further work to investigate the performance of autoregressive SVM in patients with cerebrovascular conditions.
Subject(s)
Blood Flow Velocity/physiology , Cerebrovascular Circulation/physiology , Hemodynamics/physiology , Models, Cardiovascular , Nonlinear Dynamics , Blood Pressure/physiology , Carbon Dioxide/physiology , Feedback, Physiological , Homeostasis/physiology , Humans , Inhalation/physiology , Multivariate Analysis , Rest/physiologyABSTRACT
The neural crest is induced by a combination of secreted signals. Although previous models of neural crest induction have proposed a step-wise activation of these signals, the actual spatial and temporal requirement has not been analysed. Through analysing the role of the mesoderm we show for the first time that specification of neural crest requires two temporally and chemically different steps: first, an induction at the gastrula stage dependent on signals arising from the dorsolateral mesoderm; and second, a maintenance step at the neurula stage dependent on signals from tissues adjacent to the neural crest. By performing tissue recombination experiments and using specific inhibitors of different inductive signals, we show that the first inductive step requires Wnt activation and BMP inhibition, whereas the later maintenance step requires activation of both pathways. This change in BMP necessity from BMP inhibition at gastrula to BMP activation at neurula stages is further supported by the dynamic expression of BMP4 and its antagonists, and is confirmed by direct measurements of BMP activity in the neural crest cells. The differential requirements of BMP activity allow us to propose an explanation for apparently discrepant results between chick and frog experiments. The demonstration that Wnt signals are required for neural crest induction by mesoderm solves an additional long-standing controversy. Finally, our results emphasise the importance of considering the order of exposure to signals during an inductive event.