19 research outputs found
A unified point process probabilistic framework to assess heartbeat dynamics and autonomic cardiovascular control
No full textIn recent years, time-varying inhomogeneous point process models have been introduced for assessment of instantaneous heartbeat dynamics as well as specific cardiovascular control mechanisms and hemodynamics. Assessment of the model’s statistics is established through the Wiener-Volterra theory and a multivariate autoregressive (AR) structure. A variety of instantaneous cardiovascular metrics, such as heart rate (HR), heart rate variability (HRV), respiratory sinus arrhythmia (RSA), and baroreceptor-cardiac reflex (baroreflex) sensitivity (BRS), are derived within a parametric framework and instantaneously updated with adaptive and local maximum likelihood estimation algorithms. Inclusion of second-order non-linearities, with subsequent bispectral quantification in the frequency domain, further allows for definition of instantaneous metrics of non-linearity. We here present a comprehensive review of the devised methods as applied to experimental recordings from healthy subjects during propofol anesthesia. Collective results reveal interesting dynamic trends across the different pharmacological interventions operated within each anesthesia session, confirming the ability of the algorithm to track important changes in cardiorespiratory elicited interactions, and pointing at our mathematical approach as a promising monitoring tool for an accurate, non-invasive assessment in clinical practice. We also discuss the limitations and other alternative modeling strategies of our point process approach.United States. National Institutes of Health (Grant R01-HL084502)United States. National Institutes of Health (Grant DP1-OD003646)United States. National Institutes of Health (Grant K25-NS05758)United States. National Institutes of Health (Grant DP2-OD006454)Massachusetts General Hospital. Clinical Research Center (CRC UL1 Grant RR025758
Editorial: engineering approaches to study cardiovascular physiology: modeling, estimation, and signal processing
No full textWith cardiovascular diseases being among the main causes of death in the world, quantitative modeling, assessment and monitoring of cardiovascular dynamics, and functioning play a critical role in bringing important breakthroughs to cardiovascular care. Quantification of cardiovascular physiology and its control mechanisms from physiological recordings, by use of mathematical models and algorithms, has been proved to be of important value in understanding the causes of cardiovascular diseases and assisting the diagnostic and prognostic process. This E-Book is derived from the Frontiers in Computational Physiology and Medicine Research Topic entitled “Engineering Approaches to Study Cardiovascular Physiology: Modeling, Estimation and Signal Processing.” Its goal is to bring established experts together in order to present a sample of state-of-the-art studies in cardiovascular physiology, and to give a general idea of the very different approaches that can be adopted to answer the research challenges posed by the varied, complex nature of the cardiovascular system. This book presents 10 contributions, in the form of review and original research articles
Thalamic circuit mechanisms link sensory processing in sleep and attention
No full textThe correlation between sleep integrity and attentional performance is normally interpreted as poor sleep causing impaired attention. Here, we provide an alternative explanation for this correlation: common thalamic circuits regulate sensory processing across sleep and attention, and their disruption may lead to correlated dysfunction. Using multi-electrode recordings in mice, we find that rate and rhythmicity of thalamic reticular nucleus (TRN) neurons are predictive of their functional organization in sleep and suggestive of their participation in sensory processing across states. Surprisingly, TRN neurons associated with spindles in sleep are also associated with alpha oscillations during attention. As such, we propose that common thalamic circuit principles regulate sensory processing in a state-invariant manner and that in certain disorders, targeting these circuits may be a more viable therapeutic strategy than considering individual states in isolation
Perceptual load vs. dilution: the roles of attentional focus, stimulus category, and target predictability
No full textMany studies have shown that increasing the number of neutral stimuli in a display decreases distractor interference. This result has been interpreted within two different frameworks; a perceptual load account, based on a reduction in spare resources, and a dilution account, based on a degradation in distractor representation and/or an increase in crosstalk between the distractor and the neutral stimuli that contain visually similar features. In four experiments, we systematically manipulated the extent of attentional focus, stimulus category, and preknowledge of the target to examine how these factors would interact with the display set size to influence the degree of distractor processing. Display set size did not affect the degree of distractor processing in all situations. Increasing the number of neutral items decreased distractor processing only when a task induced a broad attentional focus that included the neutral stimuli, when the neutral stimuli were in the same category as the target and distractor, and when the preknowledge of the target was insufficient to guide attention to the target efficiently. These results suggest that the effect of neutral stimuli on the degree of distractor processing is more complex than previously assumed. They provide new insight into the competitive interactions between bottom-up and top-down processes that govern the efficiency of visual selective attention
How many neural oscillators we need on sub- and supra-second intervals processing in the primate brain: comments on Gupta (2014)-Frontiers in psychology: Perception Science
No full textPsychology, MultidisciplinaryPubMedSSCI0EDITORIAL [email protected]
Thioredoxin/Txnip: Redoxisome, As a Redox Switch for the Pathogenesis of Diseases
No full textDuring the past few decades, it has been widely recognized that reducing-oxidizing (Redox) responses occurring at the intra- and extra-cellular levels are one of most important biological phenomena and dysregulated redox responses are involved in the initiation and progression of multiple diseases. Thioredoxin 1 (Trx1) and Thioredoxin 2 (Trx2), mainly located in the cytoplasm and mitochondria, respectively, are ubiquitously expressed in variety of cells and control cellular reactive oxygen species (ROS) by reducing the disulfides into thiol groups. Thioredoxin interacting protein (Txnip/TBP-2/VDUP1) directly binds to Trx1 & Trx2 (Trx) and inhibit the reducing activity of Trx through their disulfide exchange. Recent studies have revealed that Trx1 and Txnip are involved in some critical redox-dependent signal pathways including NLRP3 inflammasome activation in a redox-dependent manner. Therefore, Trx/Txnip, a redox-sensitive signaling complex is a regulator of cellular redox status and has emerged as a key component in the link between redox-regulation and the pathogenesis of diseases. Here, we review the novel functional concept of the redox-related protein complex, named Redoxisome, consisting of Trx/Txnip, as a critical regulator for intra- and extra-cellular redox signaling, involved in the pathogenesis of various diseases such as cancer, autoimmune disease, and diabetes
Unconscious processing of negative animals and objects: role of the amygdala revealed by fMRI
No full textPrevious studies have shown that emotional stimuli can be processed through the amygdala without conscious awareness. The amygdala is also involved in processing animate and social information. However, it is unclear whether different categories of pictures (e.g., animals, objects) elicit different activity in the amygdale and other regions without conscious awareness. The objective of this study was to explore whether the factors of category, emotion and picture context modulate brain activation for unconscious processing. Pictures denoting different nonhuman animals and objects in negative and neutral emotional valences were presented using a sandwich-masking paradigm. Half of them were presented with human-related information in the contexts, and half were not. Our results showed significant interaction among category, emotion and context in the amygdala and subcortical regions. Specifically, negative animals elicited stronger activation in these regions than negative objects, especially with human contexts. In addition, there were different correlation patterns between the amygdala and cortical regions according to whether they included human context. There were limited activations in cortical category-related networks. These results suggest that the amygdala and subcortical regions dominantly process negative animals, and contextual information modulates their activities, making threatening stimuli that are most relevant to human survival preferentially processed without conscious awareness
Urea transporter physiology studied in knockout mice
No full textIn mammals, there are two types of urea transporters (UTs), UT-A and UT-B. The UT-A transporter is mainly expressed in kidney epithelial cells; while UT-B demonstrates a broader distribution in kidney, heart, brain, testis, urinary tract and other tissues. Over the past few years, multiple UT knockout mouse models have been generated enabling us to explore the physiological roles of the different UTs. In the kidney, deletion of UTA1/A3 results in polyuria and a severe urine concentrating defect, indicating that intrarenal recycling of urea plays a crucial role in the overall capacity to concentrate urine. Since UT-B has a wide distribution, multiple phenotypic abnormalities were found in UT-B null mice, such as defective urine concentration, heart block with aging, depression-like behavior and earlier male sexual maturation. This review summarizes the new insights of urea transporter functions in different organs from UT knockout mice. Finally, we take a glance at the pharmacological prospect of UTs
Therapeutic efficacy and safety of Paeoniae Radix Rubra formulae in relieving hyperbilirubinemia induced by viral hepatitis: A meta-analysis
No full textObjective: Hyperbilirubinemia is one of the most devastating pathologies induced by various liver diseases. Formulae related to Paeoniae Radix Rubra (PRR) at high doses have been applied to treat hyperbilirubinemia in traditional Chinese medicine. The aim of this systematic review and meta-analysis is to assess the efficacy and safety of formulae relevant to high-dose PRR in patients suffering from hyperbilirubinemia induced by viral hepatitis.Methods: We performed a meta-analysis of randomized-controlled clinical trials to evaluate the efficacy and safety of formulae that apply a high dose of PRR for hyperbilirubinemia. Seven databases were searched until April 2015. All studies were included according to detailed criteria and assessed for methodological quality. The outcome measurements were recorded for further analysis using the Revman 5.2.11 software. Results: Fifteen articles involving 1323 patients with hyperbilirubinemia were included. Formulae with high-dose PRR might promote the efficacy of either a combined application ([OR: 3.98, 95%CI (2.91, 5.43)]; P<0.01) or a single application ([OR: 4.00, 95%CI (1.50, 10.68)]; P<0.01) for hyperbilirubinemia. The indices of TBIL, ALT and AST significantly decreased ([MD: -75.57, 95%CI (-94.88, -56.26)], [MD: -26.54, 95%CI (-36.19, -16.88)] and ([MD: -28.94, 95%CI (-46.26, -11.61)]; P<0.01), respectively. In addition, formulae with high-dose PRR could enhance the treatment efficacy of hyperbilirubinemia triggered by hepatitis B ([OR: 2.98, 95% CI (1.75, 5.05)]; P<0.01). Furthermore, the efficacy was enhanced with an increasing dosage of PRR. Two articles reported that no side effects occurred in clinical trials, and 3 studies noted that patients presented light digestive tract symptoms.Conclusion: Formulae relevant to high-dose PRR ameliorate hyperbilirubinemia and might constitute a promising therapeutic approach. For widespread acceptance by practitioners, more rigorously designed multicenter, double-blind, randomized and large-scale controlled trials are required
