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MEDICAL SCIENCES (2241 journals)            First | 1 2 3 4 5 6 7 8 | Last

Showing 601 - 800 of 3562 Journals sorted alphabetically
F&S Science : Official journal of the American Society for Reproductive Medicine     Open Access  
Facial Plastic Surgery & Aesthetic Medicine     Full-text available via subscription   (Followers: 2)
Facta Universitatis, Series : Medicine and Biology     Open Access  
Family Medicine and Community Health     Open Access   (Followers: 8)
Family Practice     Hybrid Journal   (Followers: 17)
Family Practice & Palliative Care     Open Access   (Followers: 5)
Family Practice Management     Full-text available via subscription   (Followers: 4)
Faridpur Medical College Journal     Open Access  
FEM : Revista de la Fundación Educación Médica     Open Access  
Finlay : Revista de Enfermedades no Transmisibles     Open Access  
Fisioterapia     Full-text available via subscription   (Followers: 2)
Fisioterapia & Saúde Funcional     Open Access  
Flugmedizin · Tropenmedizin · Reisemedizin - FTR     Hybrid Journal  
FMC - Formación Médica Continuada en Atención Primaria     Full-text available via subscription  
Folia Medica     Open Access  
Folia Medica Indonesiana     Open Access  
Folia Morphologica     Full-text available via subscription  
Folia Phoniatrica et Logopaedica     Full-text available via subscription   (Followers: 1)
Fontanus     Open Access  
Food Hydrocolloids for Health     Open Access  
Foodborne Pathogens and Disease     Hybrid Journal   (Followers: 11)
Foot & Ankle Specialist     Hybrid Journal   (Followers: 4)
Foot and Ankle Clinics     Full-text available via subscription   (Followers: 12)
Foot and Ankle Online Journal     Full-text available via subscription   (Followers: 6)
Forensic Science International : Mind and Law     Open Access   (Followers: 4)
Forum Medycyny Rodzinnej     Hybrid Journal  
Forum Zaburzeń Metabolicznych     Hybrid Journal  
Frontières     Full-text available via subscription   (Followers: 3)
Frontiers in Digital Health     Open Access   (Followers: 4)
Frontiers in Medical Technology     Open Access  
Frontiers in Medicine     Open Access   (Followers: 2)
Frontiers in Network Physiology     Open Access   (Followers: 2)
Frontiers in Neuroprosthetics     Open Access   (Followers: 6)
Frontiers in Synaptic Neuroscience     Open Access   (Followers: 2)
Frontiers in Tropical Diseases     Open Access  
Frontiers of Medical and Biological Engineering     Hybrid Journal  
Frontiers of Medicine     Hybrid Journal   (Followers: 2)
Fuss & Sprunggelenk     Hybrid Journal  
Future Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Future Prescriber     Hybrid Journal  
Future Science OA     Open Access  
Gaceta Médica Boliviana     Open Access  
Gaceta Médica Espirituana     Open Access  
Galen Medical Journal     Open Access  
Galician Medical Journal     Open Access   (Followers: 1)
Galle Medical Journal     Open Access  
Gefäßmedizin Scan     Hybrid Journal  
Gender and the Genome     Open Access   (Followers: 1)
Gene Expression     Full-text available via subscription   (Followers: 1)
General Reanimatology     Open Access  
Genes     Open Access   (Followers: 2)
Genome Instability & Disease     Hybrid Journal  
Geoforum     Hybrid Journal   (Followers: 25)
Gestão e Desenvolvimento     Open Access  
Ghana Medical Journal     Open Access   (Followers: 1)
GigaScience     Open Access   (Followers: 4)
Gimbernat : Revista d’Història de la Medicina i de les Ciències de la Salut     Open Access  
Glia     Hybrid Journal   (Followers: 5)
Global Advances in Health and Medicine     Open Access  
Global Bioethics     Open Access   (Followers: 5)
Global Health : Science and Practice     Open Access   (Followers: 7)
Global Health Journal     Open Access   (Followers: 2)
Global Journal of Integrated Chinese Medicine and Western Medicine     Open Access  
Global Journal of Cancer Therapy     Open Access  
Global Journal of Fertility and Research     Open Access  
Global Journal of Health Science     Open Access   (Followers: 5)
Global Journal of Infectious Diseases and Clinical Research     Open Access  
Global Journal of Medical and Clinical Case Reports     Open Access  
Global Journal of Obesity, Diabetes and Metabolic Syndrome     Open Access   (Followers: 1)
Global Journal of Perioperative Medicine     Open Access  
Global Journal of Rare Diseases     Open Access  
Global Medical & Health Communication     Open Access   (Followers: 1)
Global Reproductive Health     Open Access  
Grande Medical Journal     Open Access  
Growth Factors     Hybrid Journal   (Followers: 2)
GSTF Journal of Advances in Medical Research     Open Access  
Gümüşhane Üniversitesi Sağlık Bilimleri Dergisi     Open Access  
Hamdan Medical Journal     Open Access  
Hämostaseologie     Hybrid Journal   (Followers: 5)
Hämostaseologie     Open Access  
Hand     Hybrid Journal   (Followers: 4)
Hand Clinics     Full-text available via subscription   (Followers: 6)
Hand Therapy     Hybrid Journal   (Followers: 11)
Hard Tissue     Open Access  
Head & Face Medicine     Open Access   (Followers: 1)
Head and Neck Cancer Research     Open Access  
Head and Neck Tumors     Open Access  
Health Information : Jurnal Penelitian     Open Access  
Health Matrix : The Journal of Law-Medicine     Open Access  
Health Notions     Open Access  
Health Science Journal of Indonesia     Open Access  
Health Science Reports     Open Access   (Followers: 1)
Health Sciences and Disease     Open Access   (Followers: 1)
Health Sciences Review     Open Access  
Health Security     Hybrid Journal   (Followers: 1)
Healthcare Technology Letters     Open Access  
Hearing, Balance and Communication     Hybrid Journal   (Followers: 6)
Hearts     Open Access   (Followers: 1)
HEC Forum     Hybrid Journal   (Followers: 1)
Heighpubs Otolaryngology and Rhinology     Open Access  
Heilberufe     Hybrid Journal  
HeilberufeSCIENCE     Hybrid Journal  
Heilpflanzen     Hybrid Journal   (Followers: 3)
Helicobacter     Hybrid Journal  
HemaSphere     Open Access   (Followers: 2)
Hemoglobin     Hybrid Journal  
Hepatology, Medicine and Policy     Open Access  
HERALD of North-Western State Medical University named after I.I. Mechnikov     Open Access  
Herald of the Russian Academy of Sciences     Full-text available via subscription  
Herzschrittmachertherapie + Elektrophysiologie     Hybrid Journal  
Highland Medical Research Journal     Full-text available via subscription  
Hipertensión y Riesgo Vascular     Full-text available via subscription  
HIV Australia     Full-text available via subscription   (Followers: 3)
Homeopathy     Hybrid Journal   (Followers: 1)
Homoeopathic Links     Hybrid Journal  
Hong Kong Physiotherapy Journal     Open Access   (Followers: 14)
Horizonte Medico     Open Access  
Hormones : International Journal of Endocrinology and Metabolism     Hybrid Journal  
Hospital a Domicilio     Open Access  
Hospital Practices and Research     Open Access  
Hospital Topics     Hybrid Journal   (Followers: 1)
Hua Hin Sook Jai Klai Kangwon Journal     Open Access  
Huisarts en wetenschap     Hybrid Journal   (Followers: 4)
Human & Veterinary Medicine - International Journal of the Bioflux Society     Open Access   (Followers: 4)
Human Factors in Healthcare     Open Access  
Human Fertility     Hybrid Journal   (Followers: 4)
Humanidades Médicas     Open Access  
I.P. Pavlov Russian Medical Biological Herald     Open Access  
Iatreia     Open Access  
Ibnosina Journal of Medicine and Biomedical Sciences     Open Access  
IDCases     Open Access  
IEEE Journal of Biomedical and Health Informatics     Hybrid Journal   (Followers: 14)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal  
IEEE Journal of Translational Engineering in Health and Medicine     Open Access   (Followers: 5)
IEEE Open Journal of Engineering in Medicine and Biology     Open Access   (Followers: 1)
IEEE Transactions on Medical Robotics and Bionics     Hybrid Journal   (Followers: 3)
IEEE/ACM Transactions on Computational Biology and Bioinformatics     Hybrid Journal   (Followers: 18)
IJID Regions     Open Access   (Followers: 1)
IJS Global Health     Open Access  
IJU Case Reports     Open Access  
iLiver     Open Access   (Followers: 2)
Im OP     Hybrid Journal  
Image Analysis & Stereology     Open Access   (Followers: 1)
IMAGING     Full-text available via subscription   (Followers: 1)
Imaging in Medicine     Open Access  
Imaging Journal of Clinical and Medical Sciences     Open Access   (Followers: 1)
Imam Journal of Applied Sciences     Open Access  
Indian Journal of Ayurveda and lntegrative Medicine Klue     Open Access   (Followers: 3)
Indian Journal of Burns     Open Access   (Followers: 2)
Indian Journal of Clinical Medicine     Open Access  
Indian Journal of Community and Family Medicine     Open Access   (Followers: 2)
Indian Journal of Community Medicine     Open Access   (Followers: 1)
Indian Journal of Health Sciences and Biomedical Research KLEU     Open Access   (Followers: 2)
Indian Journal of Medical Microbiology     Open Access   (Followers: 1)
Indian Journal of Medical Research     Open Access   (Followers: 3)
Indian Journal of Medical Sciences     Open Access   (Followers: 2)
Indian Journal of Medical Specialities     Hybrid Journal  
Indian Journal of Otology     Open Access   (Followers: 1)
Indian Journal of Public Health     Open Access   (Followers: 1)
Indian Journal of Transplantation     Open Access  
Indian Spine Journal     Open Access  
Indo-Pacific Journal of Phenomenology     Open Access   (Followers: 1)
Indonesia Journal of Biomedical Science     Open Access   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Indonesian Journal for Health Sciences     Open Access   (Followers: 1)
Indonesian Journal of Medicine     Open Access  
Indonesian Journal of Tropical and Infectious Disease     Open Access  
Infant Observation: International Journal of Infant Observation and Its Applications     Hybrid Journal   (Followers: 1)
Inflammation     Hybrid Journal   (Followers: 3)
Inflammation Research     Hybrid Journal   (Followers: 4)
Info Diabetologie     Full-text available via subscription   (Followers: 1)
Infodir : Revista de Información científica para la Dirección en Salud     Open Access  
Informatics in Medicine Unlocked     Open Access  
Injury Prevention     Hybrid Journal   (Followers: 6)
InnovAiT     Hybrid Journal   (Followers: 1)
Innovare Journal of Health Science     Open Access  
Innovare Journal of Medical Science     Open Access  
Innovation in Aging     Open Access   (Followers: 1)
Inside Precision Medicine     Full-text available via subscription   (Followers: 3)
Insights in Biology and Medicine     Open Access  
Integrative and Complementary Therapies     Full-text available via subscription   (Followers: 3)
Integrative Medicine Insights     Open Access   (Followers: 1)
Integrative Medicine International     Open Access   (Followers: 1)
Integrative Medicine Research     Open Access   (Followers: 3)
Intellectual Disability Australasia     Full-text available via subscription   (Followers: 12)
Intelligence-Based Medicine     Open Access  
Intelligent Medicine     Open Access   (Followers: 1)
intensiv     Hybrid Journal   (Followers: 1)
interactive Journal of Medical Research     Open Access  
Interdisciplinary Perspectives on Infectious Diseases     Open Access  
Interdisciplinary Sciences : Computational Life Sciences     Hybrid Journal   (Followers: 2)
Internal Medicine     Open Access   (Followers: 1)
International Biomechanics     Open Access   (Followers: 1)
International Health     Hybrid Journal   (Followers: 5)
International Health Trends and Perspectives     Open Access  
International Journal for Numerical Methods in Biomedical Engineering     Hybrid Journal   (Followers: 2)
International Journal for Vitamin and Nutrition Research     Hybrid Journal   (Followers: 10)
International Journal of Academic Medicine     Open Access   (Followers: 1)
International Journal of Advance in Medical Science     Open Access  
International Journal of Advanced Medical and Health Research     Open Access  

  First | 1 2 3 4 5 6 7 8 | Last

Similar Journals
Journal Cover
Frontiers in Network Physiology
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2674-0109
Published by Frontiers Media Homepage  [96 journals]
  • The Reconstruction of Causal Networks in Physiology

    • Authors: Moritz Günther, Jan W. Kantelhardt, Ronny P. Bartsch
      Abstract: We systematically compare strengths and weaknesses of two methods that can be used to quantify causal links between time series: Granger-causality and Bivariate Phase Rectified Signal Averaging (BPRSA). While a statistical test method for Granger-causality has already been established, we show that BPRSA causality can also be probed with existing statistical tests. Our results indicate that more data or stronger interactions are required for the BPRSA method than for the Granger-causality method to detect an existing link. Furthermore, the Granger-causality method can distinguish direct causal links from indirect links as well as links that arise from a common source, while BPRSA cannot. However, in contrast to Granger-causality, BPRSA is suited for the analysis of non-stationary data. We demonstrate the practicability of the Granger-causality method by applying it to polysomnography data from sleep laboratories. An algorithm is presented, which addresses the stationarity condition of Granger-causality by splitting non-stationary data into shorter segments until they pass a stationarity test. We reconstruct causal networks of heart rate, breathing rate, and EEG amplitude from young healthy subjects, elderly healthy subjects, and subjects with obstructive sleep apnea, a condition that leads to disruption of normal respiration during sleep. These networks exhibit differences not only between different sleep stages, but also between young and elderly healthy subjects on the one hand and subjects with sleep apnea on the other hand. Among these differences are 1) weaker interactions in all groups between heart rate, breathing rate and EEG amplitude during deep sleep, compared to light and REM sleep, 2) a stronger causal link from heart rate to breathing rate but disturbances in respiratory sinus arrhythmia (breathing to heart rate coupling) in subjects with sleep apnea, 3) a stronger causal link from EEG amplitude to breathing rate during REM sleep in subjects with sleep apnea. The Granger-causality method, although initially developed for econometric purposes, can provide a quantitative, testable measure for causality in physiological networks.
      PubDate: 2022-05-03T00:00:00Z
       
  • Partial Directed Coherence and the Vector Autoregressive Modelling Myth
           and a Caveat

    • Authors: Luiz A. Baccalá, Koichi Sameshima
      Abstract: Here we dispel the lingering myth that Partial Directed Coherence is a Vector Autoregressive (VAR) Modelling dependent concept. In fact, our examples show that it is spectral factorization that lies at its heart, for which VAR modelling is a mere, albeit very efficient and convenient, device. This applies to Granger Causality estimation procedures in general and also includes instantaneous Granger effects. Care, however, must be exercised for connectivity between multivariate data generated through nonminimum phase mechanisms as it may possibly be incorrectly captured.
      PubDate: 2022-04-28T00:00:00Z
       
  • A Peri-Ictal EEG-Based Biomarker for Sudden Unexpected Death in Epilepsy
           (SUDEP) Derived From Brain Network Analysis

    • Authors: Uilki Tufa, Adam Gravitis, Katherine Zukotynski, Yotin Chinvarun, Orrin Devinsky, Richard Wennberg, Peter L. Carlen, Berj L. Bardakjian
      Abstract: Sudden unexpected death in epilepsy (SUDEP) is the leading seizure-related cause of death in epilepsy patients. There are no validated biomarkers of SUDEP risk. Here, we explored peri-ictal differences in topological brain network properties from scalp EEG recordings of SUDEP victims. Functional connectivity networks were constructed and examined as directed graphs derived from undirected delta and high frequency oscillation (HFO) EEG coherence networks in eight SUDEP and 14 non-SUDEP epileptic patients. These networks were proxies for information flow at different spatiotemporal scales, where low frequency oscillations coordinate large-scale activity driving local HFOs. The clustering coefficient and global efficiency of the network were higher in the SUDEP group pre-ictally, ictally and post-ictally (p < 0.0001 to p < 0.001), with features characteristic of small-world networks. These results suggest that cross-frequency functional connectivity network topology may be a non-invasive biomarker of SUDEP risk.
      PubDate: 2022-04-26T00:00:00Z
       
  • Why Hearing Aids Fail and How to Solve This

    • Authors: Ruedi Stoop
      Abstract: Hearing is one of the human’s foremost sensors; being able to hear again after suffering from a hearing loss is a great achievement, under all circumstances. However, in the long run, users of present-day hearing aids and cochlear implants are generally only halfway satisfied with what the commercial side offers. We demonstrate here that this is due to the failure of a full integration of these devices into the human physiological circuitry. Important parts of the hearing network that remain unestablished are the efferent connections to the cochlea, which strongly affects the faculty of listening. The latter provides the base for coping with the so-called cocktail party problem, or for a full enjoyment of multi-instrumental musical plays. While nature clearly points at how this could be remedied, to achieve this technologically will require the use of advanced high-precision electrodes and high-precision surgery, as we outline here. Corresponding efforts must be pushed forward by coordinated efforts from the side of science, as the commercial players in the field of hearing aids cannot be expected to have a substantial interest in advancements into this direction.
      PubDate: 2022-04-25T00:00:00Z
       
  • Simulating Multi-Scale Pulmonary Vascular Function by Coupling
           Computational Fluid Dynamics With an Anatomic Network Model

    • Authors: Behdad Shaarbaf Ebrahimi, Haribalan Kumar, Merryn H. Tawhai, Kelly S. Burrowes, Eric A. Hoffman, Alys R. Clark
      Abstract: The function of the pulmonary circulation is truly multi-scale, with blood transported through vessels from centimeter to micron scale. There are scale-dependent mechanisms that govern the flow in the pulmonary vascular system. However, very few computational models of pulmonary hemodynamics capture the physics of pulmonary perfusion across the spatial scales of functional importance in the lung. Here we present a multi-scale model that incorporates the 3-dimensional (3D) complexities of pulmonary blood flow in the major vessels, coupled to an anatomically-based vascular network model incorporating the multiple contributing factors to capillary perfusion, including gravity. Using the model we demonstrate how we can predict the impact of vascular remodeling and occlusion on both macro-scale functional drivers (flow distribution between lungs, and wall shear stress) and micro-scale contributors to gas exchange. The model predicts interactions between 3D and 1D models that lead to a redistribution of blood between postures, both on a macro- and a micro-scale. This allows us to estimate the effect of posture on left and right pulmonary artery wall shear stress, with predictions varying by 0.75–1.35 dyne/cm2 between postures.
      PubDate: 2022-04-25T00:00:00Z
       
  • Generalized Net Model of the Foreign Object Principle and its Network
           Physiology Interpretations

    • Authors: Krassimir Atanassov, Galya Staneva, Tania Pencheva
      Abstract: The Foreign Object Principle has been introduced in a formalized form for first time. Proven as a suitable tool for modelling of parallel processes flowing in real time, the generalized nets have been used for an interpretation of the Foreign Object Principle. It is illustrated by some examples from network physiology.
      PubDate: 2022-04-20T00:00:00Z
       
  • Pathogenic Mechanisms Underlying Cirrhotic Cardiomyopathy

    • Authors: Hongqun Liu, Henry H. Nguyen, Ki Tae Yoon, Samuel S. Lee
      Abstract: Cardiac dysfunction associated with cirrhosis in the absence of preexisting heart disease is a condition known as cirrhotic cardiomyopathy (CCM). Cardiac abnormalities consist of enlargement of cardiac chambers, attenuated systolic and diastolic contractile responses to stress stimuli, and repolarization changes. CCM may contribute to cardiovascular morbidity and mortality after liver transplantation and other major surgeries, and also to the pathogenesis of hepatorenal syndrome. The underlying mechanisms of CCM are poorly understood and as such medical therapy is an area of unmet medical need. The present review focuses on the pathogenic mechanisms responsible for development of CCM. The two major concurrent mechanistic pathways are the inflammatory phenotype due to portal hypertension, and protein/lipid synthetic/metabolic defects due to cirrhosis and liver insufficiency. The inflammatory phenotype arises from intestinal congestion due to portal hypertension, resulting in bacteria/endotoxin translocation into the systemic circulation. The cytokine storm associated with inflammation, particularly TNFα acting via NFκB depresses cardiac function. They also stimulate two evanescent gases, nitric oxide and carbon monoxide which produce cardiodepression by cGMP. Inflammation also stimulates the endocannabinoid CB-1 pathway. These systems inhibit the stimulatory beta-adrenergic contractile pathway. The liver insufficiency of cirrhosis is associated with defective synthesis or metabolism of several substances including proteins and lipids/lipoproteins. The protein defects including titin and collagen contribute to diastolic dysfunction. Other protein abnormalities such as a switch of myosin heavy chain isoforms result in systolic dysfunction. Lipid biochemical changes at the cardiac sarcolemmal plasma membrane result in increased cholesterol:phospholipid ratio and decreased membrane fluidity. Final common pathway changes involve abnormal cardiomyocyte intracellular ion kinetics, particularly calcium. In conclusion, cirrhotic cardiomyopathy is caused by two pathways of cellular and molecular dysfunction/damage due to hepatic insufficiency and portal hypertension.
      PubDate: 2022-04-19T00:00:00Z
       
  • Long-Lasting Desynchronization of Plastic Neuronal Networks by
           Double-Random Coordinated Reset Stimulation

    • Authors: Ali Khaledi-Nasab, Justus A. Kromer, Peter A. Tass
      Abstract: Hypersynchrony of neuronal activity is associated with several neurological disorders, including essential tremor and Parkinson’s disease (PD). Chronic high-frequency deep brain stimulation (HF DBS) is the standard of care for medically refractory PD. Symptoms may effectively be suppressed by HF DBS, but return shortly after cessation of stimulation. Coordinated reset (CR) stimulation is a theory-based stimulation technique that was designed to specifically counteract neuronal synchrony by desynchronization. During CR, phase-shifted stimuli are delivered to multiple neuronal subpopulations. Computational studies on CR stimulation of plastic neuronal networks revealed long-lasting desynchronization effects obtained by down-regulating abnormal synaptic connectivity. This way, networks are moved into attractors of stable desynchronized states such that stimulation-induced desynchronization persists after cessation of stimulation. Preclinical and clinical studies confirmed corresponding long-lasting therapeutic and desynchronizing effects in PD. As PD symptoms are associated with different pathological synchronous rhythms, stimulation-induced long-lasting desynchronization effects should favorably be robust to variations of the stimulation frequency. Recent computational studies suggested that this robustness can be improved by randomizing the timings of stimulus deliveries. We study the long-lasting effects of CR stimulation with randomized stimulus amplitudes and/or randomized stimulus timing in networks of leaky integrate-and-fire (LIF) neurons with spike-timing-dependent plasticity. Performing computer simulations and analytical calculations, we study long-lasting desynchronization effects of CR with and without randomization of stimulus amplitudes alone, randomization of stimulus times alone as well as the combination of both. Varying the CR stimulation frequency (with respect to the frequency of abnormal target rhythm) and the number of separately stimulated neuronal subpopulations, we reveal parameter regions and related mechanisms where the two qualitatively different randomization mechanisms improve the robustness of long-lasting desynchronization effects of CR. In particular, for clinically relevant parameter ranges double-random CR stimulation, i.e., CR stimulation with the specific combination of stimulus amplitude randomization and stimulus time randomization, may outperform regular CR stimulation with respect to long-lasting desynchronization. In addition, our results provide the first evidence that an effective reduction of the overall stimulation current by stimulus amplitude randomization may improve the frequency robustness of long-lasting therapeutic effects of brain stimulation.
      PubDate: 2022-04-19T00:00:00Z
       
  • Optical Ultrastructure of Large Mammalian Hearts Recovers Discordant
           Alternans by In Silico Data Assimilation

    • Authors: Alessandro Loppini, Julia Erhardt, Flavio H. Fenton, Simonetta Filippi, Marcel Hörning, Alessio Gizzi
      Abstract: Understanding and predicting the mechanisms promoting the onset and sustainability of cardiac arrhythmias represent a primary concern in the scientific and medical communities still today. Despite the long-lasting effort in clinical and physico-mathematical research, a critical aspect to be fully characterized and unveiled is represented by spatiotemporal alternans patterns of cardiac excitation. The identification of discordant alternans and higher-order alternating rhythms by advanced data analyses as well as their prediction by reliable mathematical models represents a major avenue of research for a broad and multidisciplinary scientific community. Current limitations concern two primary aspects: 1) robust and general-purpose feature extraction techniques and 2) in silico data assimilation within reliable and predictive mathematical models. Here, we address both aspects. At first, we extend our previous works on Fourier transformation imaging (FFI), applying the technique to whole-ventricle fluorescence optical mapping. Overall, we identify complex spatial patterns of voltage alternans and characterize higher-order rhythms by a frequency-series analysis. Then, we integrate the optical ultrastructure obtained by FFI analysis within a fine-tuned electrophysiological mathematical model of the cardiac action potential. We build up a novel data assimilation procedure demonstrating its reliability in reproducing complex alternans patterns in two-dimensional computational domains. Finally, we prove that the FFI approach applied to both experimental and simulated signals recovers the same information, thus closing the loop between the experiment, data analysis, and numerical simulations.
      PubDate: 2022-04-13T00:00:00Z
       
  • Effects of Acute Partial Sleep Deprivation and High-Intensity Interval
           Exercise on Postprandial Network Interactions

    • Authors: Zacharias Papadakis, Sergi Garcia-Retortillo, Panagiotis Koutakis
      Abstract: Introduction: High-intensity interval exercise (HIIE) is deemed effective for cardiovascular and autonomic nervous system (ANS) health-related benefits, while ANS disturbance increases the risk for cardiovascular disease (CVD). Postprandial lipemia and acute-partial sleep deprivation (APSD) are considered as CVD risk factors due to their respective changes in ANS. Exercising in the morning hours after APSD and have a high-fat breakfast afterwards may alter the interactions of the cardiovascular, autonomic regulation, and postprandial lipemic systems threatening individuals’ health. This study examined postprandial network interactions between autonomic regulation through heart rate variability (HRV) and lipemia via low-density lipoprotein (LDL) cholesterol in response to APSD and HIIE.Methods: Fifteen apparently healthy and habitually good sleepers (age 31 ± 5.2 SD yrs) completed an acute bout of an isocaloric HIIE (in form of 3:2 work-to-rest ratio at 90 and 40% of VO2 reserve) after both a reference sleep (RSX) and 3–3.5 h of acute-partial sleep deprivation (SSX) conditions. HRV time and frequency domains and LDL were evaluated in six and seven time points surrounding sleep and exercise, respectively. To identify postprandial network interactions, we constructed one correlation analysis and one physiological network for each experimental condition. To quantify the interactions within the physiological networks, we also computed the number of links (i.e., number of significant correlations).Results: We observed an irruption of negative links (i.e., negative correlations) between HRV and LDL in the SSX physiological network compared to RSX. Discussion: We recognize that a correlation analysis does not constitute a true network analysis due to the absence of analysis of a time series of the original examined physiological variables. Nonetheless, the presence of negative links in SSX reflected the impact of sleep deprivation on the autonomic regulation and lipemia and, thus, revealed the inability of HIIE to remain cardioprotective under APSD. These findings underlie the need to further investigate the effects of APSD and HIIE on the interactions among physiological systems.
      PubDate: 2022-04-13T00:00:00Z
       
  • Perspectives on Understanding Aberrant Brain Networks in Epilepsy

    • Authors: Nishant Sinha, Rasesh B. Joshi, Mani Ratnesh S. Sandhu, Theoden I. Netoff, Hitten P. Zaveri, Klaus Lehnertz
      Abstract: Epilepsy is a neurological disorder affecting approximately 70 million people worldwide. It is characterized by seizures that are complex aberrant dynamical events typically treated with drugs and surgery. Unfortunately, not all patients become seizure-free, and there is an opportunity for novel approaches to treat epilepsy using a network view of the brain. The traditional seizure focus theory presumed that seizures originated within a discrete cortical area with subsequent recruitment of adjacent cortices with seizure progression. However, a more recent view challenges this concept, suggesting that epilepsy is a network disease, and both focal and generalized seizures arise from aberrant activity in a distributed network. Changes in the anatomical configuration or widespread neural activities spanning lobes and hemispheres could make the brain more susceptible to seizures. In this perspective paper, we summarize the current state of knowledge, address several important challenges that could further improve our understanding of the human brain in epilepsy, and invite novel studies addressing these challenges.
      PubDate: 2022-04-05T00:00:00Z
       
  • Collective Activity Bursting in a Population of Excitable Units Adaptively
           Coupled to a Pool of Resources

    • Authors: Igor Franović, Sebastian Eydam, Serhiy Yanchuk, Rico Berner
      Abstract: We study the collective dynamics in a population of excitable units (neurons) adaptively interacting with a pool of resources. The resource pool is influenced by the average activity of the population, whereas the feedback from the resources to the population is comprised of components acting homogeneously or inhomogeneously on individual units of the population. Moreover, the resource pool dynamics is assumed to be slow and has an oscillatory degree of freedom. We show that the feedback loop between the population and the resources can give rise to collective activity bursting in the population. To explain the mechanisms behind this emergent phenomenon, we combine the Ott-Antonsen reduction for the collective dynamics of the population and singular perturbation theory to obtain a reduced system describing the interaction between the population mean field and the resources.
      PubDate: 2022-03-28T00:00:00Z
       
  • Emergent Diversity and Persistent Turnover in Evolving Microbial
           Cross-Feeding Networks

    • Authors: Leonhard Lücken, Sinikka T. Lennartz, Jule Froehlich, Bernd Blasius
      Abstract: A distinguishing feature of many ecological networks in the microbial realm is the diversity of substrates that could potentially serve as energy sources for microbial consumers. The microorganisms are themselves the agents of compound diversification via metabolite excretion or overflow metabolism. It has been suggested that the emerging richness of different substrates is an important condition for the immense biological diversity in microbial ecosystems. In this work, we study how complex cross-feeding networks (CFN) of microbial species may develop from a simple initial community given some elemental evolutionary mechanisms of resource-dependent speciation and extinctions using a network flow model. We report results of several numerical experiments and report an in-depth analysis of the evolutionary dynamics. We find that even in stable environments, the system is subject to persisting turnover, indicating an ongoing co-evolution. Further, we compare the impact of different parameters, such as the ratio of mineralization, as well as the metabolic versatility and variability on the evolving community structure. The results imply that high microbial and molecular diversity is an emergent property of evolution in cross-feeding networks, which affects transformation and accumulation of substrates in natural systems, such as soils and oceans, with potential relevance to biotechnological applications.
      PubDate: 2022-03-24T00:00:00Z
       
  • The Fractal Tapestry of Life: II Entailment of Fractional Oncology by
           Physiology Networks

    • Authors: Bruce J. West
      Abstract: This is an essay advocating the efficacy of using the (noninteger) fractional calculus (FC) for the modeling of complex dynamical systems, specifically those pertaining to biomedical phenomena in general and oncological phenomena in particular. Herein we describe how the integer calculus (IC) is often incapable of describing what were historically thought to be simple linear phenomena such as Newton’s law of cooling and Brownian motion. We demonstrate that even linear dynamical systems may be more accurately described by fractional rate equations (FREs) when the experimental datasets are inconsistent with models based on the IC. The Network Effect is introduced to explain how the collective dynamics of a complex network can transform a many-body noninear dynamical system modeled using the IC into a set of independent single-body fractional stochastic rate equations (FSREs). Note that this is not a mathematics paper, but rather a discussion focusing on the kinds of phenomena that have historically been approximately and improperly modeled using the IC and how a FC replacement of the model better explains the experimental results. This may be due to hidden effects that were not anticapated in the IC model, or to an effect that was acknowledged as possibly significant, but beyond the mathematical skills of the investigator to Incorporate into the original model. Whatever the reason we introduce the FRE used to describe mathematical oncology (MO) and review the quality of fit of such models to tumor growth data. The analytic results entailed in MO using ordinary diffusion as well as fractional diffusion are also briefly discussed. A connection is made between a time-dependent fractional-order derivative, technically called a distributed-order parameter, and the multifractality of time series, such that an observed multifractal time series can be modeled using a FRE with a distributed fractional-order derivative. This equivalence between multifractality and distributed fractional derivatives has not received the recognition in the applications literature we believe it warrants.
      PubDate: 2022-03-24T00:00:00Z
       
  • Body Weight Control Is a Key Element of Motor Control for Toddlers’
           Walking

    • Authors: Jennifer N. Kerkman, Coen S. Zandvoort, Andreas Daffertshofer, Nadia Dominici
      Abstract: New-borns can step when supported for about 70–80% of their own body weight. Gravity-related sensorimotor information might be an important factor in developing the ability to walk independently. We explored how body weight support alters motor control in toddlers during the first independent steps and in toddlers with about half a year of walking experience. Sixteen different typically developing children were assessed during (un)supported walking on a running treadmill. Electromyography of 18–24 bilateral leg and back muscles and vertical ground reaction forces were recorded. Strides were grouped into four levels of body weight support ranging from no (
      PubDate: 2022-03-24T00:00:00Z
       
  • A Personalized Spring Network Representation of Emphysematous Lungs From
           CT Images

    • Authors: Ziwen Yuan, Jacob Herrmann, Samhita Murthy, Kevin Peters, Sarah E. Gerard, Hadi T. Nia, Kenneth R. Lutchen, Béla Suki
      Abstract: Emphysema is a progressive disease characterized by irreversible tissue destruction and airspace enlargement, which manifest as low attenuation area (LAA) on CT images. Previous studies have shown that inflammation, protease imbalance, extracellular matrix remodeling and mechanical forces collectively influence the progression of emphysema. Elastic spring network models incorporating force-based mechanical failure have been applied to investigate the pathogenesis and progression of emphysema. However, these models were general without considering the patient-specific information on lung structure available in CT images. The aim of this work was to develop a novel approach that provides an optimal spring network representation of emphysematous lungs based on the apparent density in CT images, allowing the construction of personalized networks. The proposed method takes into account the size and curvature of LAA clusters on the CT images that correspond to a pre-stressed condition of the lung as opposed to a naïve method that excludes the effects of pre-stress. The main findings of this study are that networks constructed by the new method 1) better preserve LAA cluster sizes and their distribution than the naïve method; and 2) predict different course of emphysema progression compared to the naïve method. We conclude that our new method has the potential to predict patient-specific emphysema progression which needs verification using clinical data.
      PubDate: 2022-03-18T00:00:00Z
       
  • Towards a Data-Driven Estimation of Resilience in Networked Dynamical
           Systems: Designing a Versatile Testbed

    • Authors: Tobias Fischer, Thorsten Rings, M. Reza Rahimi Tabar, Klaus Lehnertz
      Abstract: Estimating resilience of adaptive, networked dynamical systems remains a challenge. Resilience refers to a system’s capacity “to absorb exogenous and/or endogenous disturbances and to reorganize while undergoing change so as to still retain essentially the same functioning, structure, and feedbacks.” The majority of approaches to estimate resilience requires exact knowledge of the underlying equations of motion; the few data-driven approaches so far either lack appropriate strategies to verify their suitability or remain subject of considerable debate. We develop a testbed that allows one to modify resilience of a multistable networked dynamical system in a controlled manner. The testbed also enables generation of multivariate time series of system observables to evaluate the suitability of data-driven estimators of resilience. We report first findings for such an estimator.
      PubDate: 2022-03-17T00:00:00Z
       
  • Effects of Supplemental Oxygen on Cardiovascular and Respiratory
           Interactions by Extended Partial Directed Coherence in Idiopathic
           Pulmonary Fibrosis

    • Authors: Laura M. Santiago-Fuentes, Sonia Charleston-Villalobos, Ramón González-Camarena, Andreas Voss, Mayra E. Mejía-Avila, Ivette Buendía-Roldan, Sina Reulecke, Tomás Aljama-Corrales
      Abstract: Idiopathic pulmonary fibrosis (IPF) is a chronic and restrictive disease characterized by fibrosis and inflammatory changes in lung tissue producing a reduction in diffusion capacity and leading to exertional chronic arterial hypoxemia and dyspnea. Furthermore, clinically, supplemental oxygen (SupplO2) has been prescribed to IPF patients to improve symptoms. However, the evidence about the benefits or disadvantages of oxygen supplementation is not conclusive. In addition, the impact of SupplO2 on the autonomic nervous system (ANS) regulation in respiratory diseases needs to be evaluated. In this study the interactions between cardiovascular and respiratory systems in IPF patients, during ambient air (AA) and SupplO2 breathing, are compared to those from a matched healthy group. Interactions were estimated by time series of successive beat-to-beat intervals (BBI), respiratory amplitude (RESP) at BBI onset, arterial systolic (SYS) and diastolic (DIA) blood pressures. The paper explores the Granger causality (GC) between systems in the frequency domain by the extended partial directed coherence (ePDC), considering instantaneous effects. Also, traditional linear and nonlinear markers as power in low (LF) and high frequency (HF) bands, symbolic dynamic indices as well as arterial baroreflex, were calculated. The results showed that for IPF during AA phase: 1) mean BBI and power of BBI-HF band, as well as mean respiratory frequency were significantly lower (p < 0.05) and higher (p < 0.001), respectively, indicating a strong sympathetic influence, and 2) the RESP → SYS interaction was characterized by Mayer waves and diminished RESP → BBI, i.e., decreased respiratory sinus arrhythmia. In contrast, during short-term SupplO2 phase: 1) oxygen might produce a negative influence on the systolic blood pressure variability, 2) the arterial baroreflex reduced significantly (p < 0.01) and 3) reduction of RSA reflected by RESP → BBI with simultaneous increase of Traube-Hering waves in RESP → SYS (p < 0.001), reflected increased sympathetic modulation to the vessels. The results gathered in this study may be helpful in the management of the administration of SupplO2.
      PubDate: 2022-03-15T00:00:00Z
       
  • Linear and Nonlinear Directed Connectivity Analysis of the
           Cardio-Respiratory System in Type 1 Diabetes

    • Authors: Michele Sorelli, T. Noah Hutson, Leonidas Iasemidis, Leonardo Bocchi
      Abstract: In this study, we explored the possibility of developing non-invasive biomarkers for patients with type 1 diabetes (T1D) by quantifying the directional couplings between the cardiac, vascular, and respiratory systems, treating them as interconnected nodes in a network configuration. Towards this goal, we employed a linear directional connectivity measure, the directed transfer function (DTF), estimated by a linear multivariate autoregressive modelling of ECG, respiratory and skin perfusion signals, and a nonlinear method, the dynamical Bayesian inference (DBI) analysis of bivariate phase interactions. The physiological data were recorded concurrently for a relatively short time period (5 min) from 10 healthy control subjects and 10 T1D patients. We found that, in both control and T1D subjects, breathing had greater influence on the heart and perfusion with respect to the opposite coupling direction and that, by both employed methods of analysis, the causal influence of breathing on the heart was significantly decreased (p < 0.05) in T1D patients compared to the control group. These preliminary results, although obtained from a limited number of subjects, provide a strong indication for the usefulness of a network-based multi-modal analysis for the development of biomarkers of T1D-related complications from short-duration data, as well as their potential in the exploration of the pathophysiological mechanisms that underlie this devastating and very widespread disease.
      PubDate: 2022-03-08T00:00:00Z
       
  • Spike-Timing-Dependent Plasticity Mediated by Dopamine and its Role in
           Parkinson’s Disease Pathophysiology

    • Authors: Mojtaba Madadi Asl, Abdol-Hossein Vahabie, Alireza Valizadeh, Peter A. Tass
      Abstract: Parkinson’s disease (PD) is a multi-systemic neurodegenerative brain disorder. Motor symptoms of PD are linked to the significant dopamine (DA) loss in substantia nigra pars compacta (SNc) followed by basal ganglia (BG) circuit dysfunction. Increasing experimental and computational evidence indicates that (synaptic) plasticity plays a key role in the emergence of PD-related pathological changes following DA loss. Spike-timing-dependent plasticity (STDP) mediated by DA provides a mechanistic model for synaptic plasticity to modify synaptic connections within the BG according to the neuronal activity. To shed light on how DA-mediated STDP can shape neuronal activity and synaptic connectivity in the PD condition, we reviewed experimental and computational findings addressing the modulatory effect of DA on STDP as well as other plasticity mechanisms and discussed their potential role in PD pathophysiology and related network dynamics and connectivity. In particular, reshaping of STDP profiles together with other plasticity-mediated processes following DA loss may abnormally modify synaptic connections in competing pathways of the BG. The cascade of plasticity-induced maladaptive or compensatory changes can impair the excitation-inhibition balance towards the BG output nuclei, leading to the emergence of pathological activity-connectivity patterns in PD. Pre-clinical, clinical as well as computational studies reviewed here provide an understanding of the impact of synaptic plasticity and other plasticity mechanisms on PD pathophysiology, especially PD-related network activity and connectivity, after DA loss. This review may provide further insights into the abnormal structure-function relationship within the BG contributing to the emergence of pathological states in PD. Specifically, this review is intended to provide detailed information for the development of computational network models for PD, serving as testbeds for the development and optimization of invasive and non-invasive brain stimulation techniques. Computationally derived hypotheses may accelerate the development of therapeutic stimulation techniques and potentially reduce the number of related animal experiments.
      PubDate: 2022-03-04T00:00:00Z
       
 
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