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Journal articles on the topic 'Local feedback regulation'
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Taghvafard, Hadi, Alexander Medvedev, Anton V. Proskurnikov, and Ming Cao. "Impulsive model of endocrine regulation with a local continuous feedback." Mathematical Biosciences 310 (April 2019): 128–35. http://dx.doi.org/10.1016/j.mbs.2019.02.006.
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Takeda, S., C. Gapper, H. Kaya, E. Bell, K. Kuchitsu, and L. Dolan. "Local Positive Feedback Regulation Determines Cell Shape in Root Hair Cells." Science 319, no. 5867 (February 29, 2008): 1241–44. http://dx.doi.org/10.1126/science.1152505.
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Miao, Zhixin, and Lingling Fan. "Achieving Economic Operation and Secondary Frequency Regulation Simultaneously Through Local Feedback Control." IEEE Transactions on Power Systems 32, no. 1 (January 2017): 85–93. http://dx.doi.org/10.1109/tpwrs.2016.2544847.
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Taghvafard, Hadi, Anton V. Proskurnikov, and Ming Cao. "Local and global analysis of endocrine regulation as a non-cyclic feedback system." Automatica 91 (May 2018): 190–96. http://dx.doi.org/10.1016/j.automatica.2018.01.035.
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Walker, J. J., F. Spiga, R. Gupta, Z. Zhao, S. L. Lightman, and J. R. Terry. "Rapid intra-adrenal feedback regulation of glucocorticoid synthesis." Journal of The Royal Society Interface 12, no. 102 (January 2015): 20140875. http://dx.doi.org/10.1098/rsif.2014.0875.
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The hypothalamic–pituitary–adrenal axis is a vital neuroendocrine system that regulates the secretion of glucocorticoid hormones from the adrenal glands. This system is characterized by a dynamic ultradian hormonal oscillation, and in addition is highly responsive to stressful stimuli. We have recently shown that a primary mechanism generating this ultradian rhythm is a systems-level interaction where adrenocorticotrophin hormone (ACTH) released from the pituitary stimulates the secretion of adrenal glucocorticoids, which in turn feedback at the level of the pituitary to rapidly inhibit ACTH secretion. In this study, we combine experimental physiology and mathematical modelling to investigate intra-adrenal mechanisms regulating glucocorticoid synthesis. Our modelling results suggest that glucocorticoids can inhibit their own synthesis through a very rapid (within minutes), presumably non-genomic, intra-adrenal pathway. We present further evidence for the existence of a short time delay in this intra-adrenal inhibition, and also that at the initiation of each ACTH stimulus, this local feedback mechanism is rapidly antagonized, presumably via activation of the specific ACTH receptor (MC2R) signalling pathway. This mechanism of intra-adrenal inhibition enables the gland to rapidly release glucocorticoids while at the same time preventing uncontrolled release of glucocorticoids in response to large surges in ACTH associated with stress.
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Song, Yohan, Anping Xia, Hee Yoon Lee, Rosalie Wang, Anthony J. Ricci, and John S. Oghalai. "Activity-dependent regulation of prestin expression in mouse outer hair cells." Journal of Neurophysiology 113, no. 10 (June 2015): 3531–42. http://dx.doi.org/10.1152/jn.00869.2014.
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Prestin is a membrane protein necessary for outer hair cell (OHC) electromotility and normal hearing. Its regulatory mechanisms are unknown. Several mouse models of hearing loss demonstrate increased prestin, inspiring us to investigate how hearing loss might feedback onto OHCs. To test whether centrally mediated feedback regulates prestin, we developed a novel model of inner hair cell loss. Injection of diphtheria toxin (DT) into adult CBA mice produced significant loss of inner hair cells without affecting OHCs. Thus, DT-injected mice were deaf because they had no afferent auditory input despite OHCs continuing to receive normal auditory mechanical stimulation and having normal function. Patch-clamp experiments demonstrated no change in OHC prestin, indicating that loss of information transfer centrally did not alter prestin expression. To test whether local mechanical feedback regulates prestin, we used TectaC1509G mice, where the tectorial membrane is malformed and only some OHCs are stimulated. OHCs connected to the tectorial membrane had normal prestin levels, whereas OHCs not connected to the tectorial membrane had elevated prestin levels, supporting an activity-dependent model. To test whether the endocochlear potential was necessary for prestin regulation, we studied TectaC1509G mice at different developmental ages. OHCs not connected to the tectorial membrane had lower than normal prestin levels before the onset of the endocochlear potential and higher than normal prestin levels after the onset of the endocochlear potential. Taken together, these data indicate that OHC prestin levels are regulated through local feedback that requires mechanoelectrical transduction currents. This adaptation may serve to compensate for variations in the local mechanical environment.
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Wilde, C. J., C. V. P. Addey, L. M. Boddy, and M. Peaker. "Autocrine regulation of milk secretion by a protein in milk." Biochemical Journal 305, no. 1 (January 1, 1995): 51–58. http://dx.doi.org/10.1042/bj3050051.
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Frequency or completeness of milk removal from the lactating mammary gland regulates the rate of milk secretion by a mechanism which is local, chemical and inhibitory in nature. Screening of goat's milk proteins in rabbit mammary explant cultures identified a single whey protein of M(r) 7600 able to inhibit synthesis of milk constituents. The active whey protein, which we term FIL (Feedback inhibitor of Lactation), also decreased milk secretion temporarily when introduced into a mammary gland of lactating goats. FIL was synthesized by primary cultures of goat mammary epithelial cells, and was secreted vectorially together with other milk proteins. N-terminal amino acid sequencing indicated that it is a hitherto unknown protein. The evidence indicates that local regulation of milk secretion by milk removal is through autocrine feedback inhibition by this milk protein.
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Abelew, Thomas A., Melissa D. Miller, Timothy C. Cope, and T. Richard Nichols. "Local Loss of Proprioception Results in Disruption of Interjoint Coordination During Locomotion in the Cat." Journal of Neurophysiology 84, no. 5 (November 1, 2000): 2709–14. http://dx.doi.org/10.1152/jn.2000.84.5.2709.
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To investigate the role of localized, proprioceptive feedback in the regulation of interjoint coordination during locomotion, we substantially attenuated neural feedback from the triceps surae muscles in one hindlimb in each of four cats using the method of self-reinnervation. After allowing the recovery of motor innervation, the animals were filmed during level and ramp walking. Deficits were small or undetectable during walking on the level surface or up the ramp, behaviors that require a large range of forces in the triceps surae muscles. During walking down the ramp, when the triceps surae muscles normally undergo active lengthening, the ankle joint underwent a large yield and the coordination between ankle and knee was disrupted. The correlation of the deficit with the direction of length change and not muscle force suggested that a loss of feedback from muscle spindle receptors was primarily responsible for the deficit. These results indicate an important role for the stretch reflex and stiffness regulation during locomotion.
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Stewart, G. M., C. V. P. Addey, C. H. Knight, and C. J. Wilde. "AUTOCRINE REGULATION OF CASEIN TURNOVER IN GOAT MAMMARY EXPLANTS." Journal of Endocrinology 118, no. 1 (July 1988): R1—R3. http://dx.doi.org/10.1677/joe.0.118r001.
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ABSTRACT Local feedback control of milk protein secretion was investigated in goat mammary explants by measuring degradation of newly synthesized casein in the presence of a goat milk whey fraction. Reduced net synthesis of [3H]casein in the presence of the milk fraction was due, at least in part, to its degradation during secretion, suggesting that this process is under autocrine regulation.
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Emek, Sevcan, Vedat Evren, and Şebnem Bora. "Simulation of glucose regulating mechanism with an agent-based software engineering tool." An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 9, no. 3 (March 20, 2019): 15–20. http://dx.doi.org/10.11121/ijocta.01.2019.00685.
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This study provides a detailed explanation of a regulating mechanism of the blood glucose levels by an agent-based software engineering tool. Repast Simphony which is used in implementation of this study is an agent-based software engineering tool based on the object-oriented programming using Java language. Agent-based modeling and simulation is a computational methodology for simulating and exploring phenomena that includes a large set of active components represented by agents. The agents are main components situated in space and time of agent-based simulation environment. In this study, we present hormonal regulation of blood glucose levels by our improved agent-based control mechanism. Hormonal regulation of blood glucose levels is an important process to maintain homeostasis inside the human body. We offer a negative feedback control mechanism with agent-based modeling approach to regulate the secretion of insulin hormone which is responsible for increasing the blood glucose levels. The negative feedback control mechanism run by three main agents that interact with each other to perform their local actions in the simulation environment. The result of this study shows the local behavior of the agents in the negative feedback loop and illustrates how to balance the blood glucose levels. Finally, this study which is thought a potential implementation of agent-based modeling and simulation may contribute to the exploration of other homeostatic control systems inside the human body.
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Schubert, M. L., N. F. Edwards, and G. M. Makhlouf. "Regulation of gastric somatostatin secretion in the mouse by luminal acidity: A local feedback mechanism." Gastroenterology 94, no. 2 (February 1988): 317–22. http://dx.doi.org/10.1016/0016-5085(88)90418-0.
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Mullur, Rashmi, Yan-Yun Liu, and Gregory A. Brent. "Thyroid Hormone Regulation of Metabolism." Physiological Reviews 94, no. 2 (April 2014): 355–82. http://dx.doi.org/10.1152/physrev.00030.2013.
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Thyroid hormone (TH) is required for normal development as well as regulating metabolism in the adult. The thyroid hormone receptor (TR) isoforms, α and β, are differentially expressed in tissues and have distinct roles in TH signaling. Local activation of thyroxine (T4), to the active form, triiodothyronine (T3), by 5′-deiodinase type 2 (D2) is a key mechanism of TH regulation of metabolism. D2 is expressed in the hypothalamus, white fat, brown adipose tissue (BAT), and skeletal muscle and is required for adaptive thermogenesis. The thyroid gland is regulated by thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH). In addition to TRH/TSH regulation by TH feedback, there is central modulation by nutritional signals, such as leptin, as well as peptides regulating appetite. The nutrient status of the cell provides feedback on TH signaling pathways through epigentic modification of histones. Integration of TH signaling with the adrenergic nervous system occurs peripherally, in liver, white fat, and BAT, but also centrally, in the hypothalamus. TR regulates cholesterol and carbohydrate metabolism through direct actions on gene expression as well as cross-talk with other nuclear receptors, including peroxisome proliferator-activated receptor (PPAR), liver X receptor (LXR), and bile acid signaling pathways. TH modulates hepatic insulin sensitivity, especially important for the suppression of hepatic gluconeogenesis. The role of TH in regulating metabolic pathways has led to several new therapeutic targets for metabolic disorders. Understanding the mechanisms and interactions of the various TH signaling pathways in metabolism will improve our likelihood of identifying effective and selective targets.
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Yu, Lu, and Jinzhi Wang. "Cooperative Control for Uncertain Multiagent Systems via Distributed Output Regulation." Mathematical Problems in Engineering 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/898375.
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The distributed robust output regulation problem for multiagent systems is considered. For heterogeneous uncertain linear systems and a linear exosystem, the controlling aim is to stabilize the closed-loop system and meanwhile let the regulated outputs converge to the origin asymptotically, by the help of local interaction. The communication topology considered is directed acyclic graphs, which means directed graphs without loops. With distributed dynamic state feedback controller and output feedback controller, respectively, the solvability of the problem and the algorithm of controller design are both investigated. The solvability conditions are given in terms of linear matrix inequalities (LMIs). It is shown that, for polytopic uncertainties, the distributed controllers constructed by solving LMIs can satisfy the requirements of output regulation property.
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Glanowska, Katarzyna M., and Suzanne M. Moenter. "Endocannabinoids and prostaglandins both contribute to GnRH neuron-GABAergic afferent local feedback circuits." Journal of Neurophysiology 106, no. 6 (December 2011): 3073–81. http://dx.doi.org/10.1152/jn.00046.2011.
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Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for central control of fertility. Regulation of GnRH neurons by long-loop gonadal steroid feedback through steroid receptor-expressing afferents such as GABAergic neurons is well studied. Recently, local central feedback circuits regulating GnRH neurons were identified. GnRH neuronal depolarization induces short-term inhibition of their GABAergic afferents via a mechanism dependent on metabotropic glutamate receptor (mGluR) activation. GnRH neurons are enveloped in astrocytes, which express mGluRs. GnRH neurons also produce endocannabinoids, which can be induced by mGluR activation. We hypothesized the local GnRH-GABA circuit utilizes glia-derived and/or cannabinoid mechanisms and is altered by steroid milieu. Whole cell voltage-clamp was used to record GABAergic postsynaptic currents (PSCs) from GnRH neurons before and after action potential-like depolarizations were mimicked. In GnRH neurons from ovariectomized (OVX) mice, this depolarization reduced PSC frequency. This suppression was blocked by inhibition of prostaglandin synthesis with indomethacin, by a prostaglandin receptor antagonist, or by a specific glial metabolic poison, together suggesting the postulate that prostaglandins, potentially glia-derived, play a role in this circuit. This circuit was also inhibited by a CB1 receptor antagonist or by blockade of endocannabinoid synthesis in GnRH neurons, suggesting an endocannabinoid element, as well. In females, local circuit inhibition persisted in androgen-treated mice but not in estradiol-treated mice or young ovary-intact mice. In contrast, local circuit inhibition was present in gonad-intact males. These data suggest GnRH neurons interact with their afferent neurons using multiple mechanisms and that these local circuits can be modified by both sex and steroid feedback.
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Burt, Julia, Christian O. Alberto, Matthew P. Parsons, and Michiru Hirasawa. "Local network regulation of orexin neurons in the lateral hypothalamus." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 301, no. 3 (September 2011): R572—R580. http://dx.doi.org/10.1152/ajpregu.00674.2010.
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Obesity and inadequate sleep are among the most common causes of health problems in modern society. Thus, the discovery that orexin (hypocretin) neurons play a pivotal role in sleep/wake regulation, energy balance, and consummatory behaviors has sparked immense interest in understanding the regulatory mechanisms of these neurons. The local network consisting of neurons and astrocytes within the lateral hypothalamus and perifornical area (LH/PFA), where orexin neurons reside, shapes the output of orexin neurons and the LH/PFA. Orexin neurons not only send projections to remote brain areas but also contribute to the local network where they release multiple neurotransmitters to modulate its activity. These neurotransmitters have opposing actions, whose balance is determined by the amount released and postsynaptic receptor desensitization. Modulation and negative feedback regulation of excitatory glutamatergic inputs as well as release of astrocyte-derived factors, such as lactate and ATP, can also affect the excitability of orexin neurons. Furthermore, distinct populations of LH/PFA neurons express neurotransmitters with known electrophysiological actions on orexin neurons, such as melanin-concentrating hormone, corticotropin-releasing factor, thyrotropin-releasing hormone, neurotensin, and GABA. These LH/PFA-specific mechanisms may be important for fine tuning the firing activity of orexin neurons to maintain optimal levels of prolonged output to sustain wakefulness and stimulate consummatory behaviors. Building on these exciting findings should shed further light onto the cellular mechanisms of energy balance and sleep-wake regulation.
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Hearn, Timothy J., and Alex A. R. Webb. "Recent advances in understanding regulation of the Arabidopsis circadian clock by local cellular environment." F1000Research 9 (January 27, 2020): 51. http://dx.doi.org/10.12688/f1000research.21307.1.
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Circadian clocks have evolved to synchronise an organism’s physiology with the environmental rhythms driven by the Earth’s rotation on its axis. Over the past two decades, many of the genetic components of the Arabidopsis thaliana circadian oscillator have been identified. The interactions between these components have been formulized into mathematical models that describe the transcriptional translational feedback loops of the oscillator. More recently, focus has turned to the regulation and functions of the circadian clock. These studies have shown that the system dynamically responds to environmental signals and small molecules. We describe advances that have been made in discovering the cellular mechanisms by which signals regulate the circadian oscillator of Arabidopsis in the context of tissue-specific regulation.
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Serrano, M. Ángeles, Manuel Jurado, and Ramon Reigada. "Negative feedback self-regulation contributes to robust and high-fidelity transmembrane signal transduction." Journal of The Royal Society Interface 10, no. 88 (November 6, 2013): 20130581. http://dx.doi.org/10.1098/rsif.2013.0581.
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We present a minimal motif model for transmembrane cell signalling. The model assumes signalling events taking place in spatially distributed nanoclusters regulated by a birth/death dynamics. The combination of these spatio-temporal aspects can be modulated to provide a robust and high-fidelity response behaviour without invoking sophisticated modelling of the signalling process as a sequence of cascade reactions and fine-tuned parameters. Our results show that the fact that the distributed signalling events take place in nanoclusters with a finite lifetime regulated by local production is sufficient to obtain a robust and high-fidelity response.
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Dekel, Avishai, Kartick C. Sarkar, Fangzhou Jiang, Frederic Bournaud, Mark R. Krumholz, Daniel Ceverino, and Joel R. Primack. "The global star formation law by supernova feedback." Monthly Notices of the Royal Astronomical Society 488, no. 4 (July 15, 2019): 4753–78. http://dx.doi.org/10.1093/mnras/stz1919.
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ABSTRACT We address a simple model where the Kennicutt–Schmidt (KS) relation between the macroscopic densities of star formation rate (SFR, ρsfr) and gas (n) in galactic discs emerges from self-regulation of the SFR via supernova feedback. It arises from the physics of supernova bubbles, insensitive to the microscopic SFR recipe and not explicitly dependent on gravity. The key is that the filling factor of SFR-suppressed supernova bubbles self-regulates to a constant, f ∼ 0.5. Expressing the bubble fading radius and time in terms of n, the filling factor is $f\propto S\, n^{-s}$ with s ≃ 1.5, where S is the supernova rate density. A constant f thus refers to ρsfr ∝ n1.5, with a density-independent SFR efficiency per free-fall time ∼0.01. The self-regulation to f ∼ 0.5 and the convergence to a KS relation independent of the local SFR recipe are demonstrated in cosmological and isolated-galaxy simulations using different codes and recipes. In parallel, the spherical analysis of bubble evolution is generalized to clustered supernovae, analytically and via simulations, yielding s ≃ 1.5 ± 0.5. An analysis of photoionized bubbles about pre-supernova stars yields a range of KS slopes but the KS relation is dominated by the supernova bubbles. Superbubble blowouts may lead to an alternative self-regulation by outflows and recycling. While the model is oversimplified, its simplicity and validity in the simulations may argue that it captures the origin of the KS relation.
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Alisafaei, Farid, Doorgesh Sharma Jokhun, G. V. Shivashankar, and Vivek B. Shenoy. "Regulation of nuclear architecture, mechanics, and nucleocytoplasmic shuttling of epigenetic factors by cell geometric constraints." Proceedings of the National Academy of Sciences 116, no. 27 (June 17, 2019): 13200–13209. http://dx.doi.org/10.1073/pnas.1902035116.
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Cells sense mechanical signals from their microenvironment and transduce them to the nucleus to regulate gene expression programs. To elucidate the physical mechanisms involved in this regulation, we developed an active 3D chemomechanical model to describe the three-way feedback between the adhesions, the cytoskeleton, and the nucleus. The model shows local tensile stresses generated at the interface of the cell and the extracellular matrix regulate the properties of the nucleus, including nuclear morphology, levels of lamin A,C, and histone deacetylation, as these tensile stresses 1) are transmitted to the nucleus through cytoskeletal physical links and 2) trigger an actomyosin-dependent shuttling of epigenetic factors. We then show how cell geometric constraints affect the local tensile stresses and subsequently the three-way feedback and induce cytoskeleton-mediated alterations in the properties of the nucleus such as nuclear lamina softening, chromatin stiffening, nuclear lamina invaginations, increase in nuclear height, and shrinkage of nuclear volume. We predict a phase diagram that describes how the disruption of cytoskeletal components impacts the feedback and subsequently induce contractility-dependent alterations in the properties of the nucleus. Our simulations show that these changes in contractility levels can be also used as predictors of nucleocytoplasmic shuttling of transcription factors and the level of chromatin condensation. The predictions are experimentally validated by studying the properties of nuclei of fibroblasts on micropatterned substrates with different shapes and areas.
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Fliers, Eric, Andries Kalsbeek, and Anita Boelen. "MECHANISMS IN ENDOCRINOLOGY: Beyond the fixed setpoint of the hypothalamus–pituitary–thyroid axis." European Journal of Endocrinology 171, no. 5 (November 2014): R197—R208. http://dx.doi.org/10.1530/eje-14-0285.
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The hypothalamus–pituitary–thyroid (HPT) axis represents a classical example of an endocrine feedback loop. This review discusses dynamic changes in HPT axis setpoint regulation, identifying their molecular and cellular determinants, and speculates about their functional role. Hypothalamic thyrotropin-releasing hormone neurons were identified as key components of thyroid hormone (TH) setpoint regulation already in the 1980s, and this was followed by the demonstration of a pivotal role for the thyroid hormone receptor beta in negative feedback of TH on the hypothalamic and pituitary level. Gradually, the concept emerged of the HPT axis setpoint as a fixed entity, aiming at a particular TH serum concentration. However, TH serum concentrations appear to be variable and highly responsive to physiological and pathophysiological environmental factors, including the availability or absence of food, inflammation and clock time. During food deprivation and inflammation, TH serum concentrations decrease without a concomitant rise in serum TSH, reflecting a deviation from negative feedback regulation in the HPT axis. Surprisingly, TH action in peripheral organs in these conditions cannot be simply predicted by decreased serum TH concentrations. Instead, diverse environmental stimuli have differential effects on local TH metabolism, e.g. in liver and muscle, occurring quite independently from decreased TH serum concentrations. The net effect of these differential local changes is probably a major determinant of TH action at the tissue level. In sum, hypothalamic HPT axis setpoint regulation as well as TH metabolism at the peripheral organ level is flexible and dynamic, and may adapt the organism in an optimal way to a range of environmental challenges.
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Schnermann, Jurgen. "Juxtaglomerular cell complex in the regulation of renal salt excretion." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, no. 2 (February 1, 1998): R263—R279. http://dx.doi.org/10.1152/ajpregu.1998.274.2.r263.
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Luminal NaCl concentration at the macula densa (MD) has the two established effects of regulating glomerular arteriolar resistance and renin secretion. Tubuloglomerular feedback (TGF), the inverse relationship between MD NaCl concentration and glomerular filtration rate (GFR), stabilizes distal salt delivery and thereby NaCl excretion in response to random perturbations unrelated to changes in body salt balance. Control of vasomotor tone by TGF is exerted primarily by NaCl transport-dependent changes in local adenosine concentrations. During long-lasting perturbations of MD NaCl concentration, control of renin secretion becomes the dominant function of the MD. The potentially maladaptive effect of TGF under chronic conditions is prevented by TGF adaptations, permitting adjustments in GFR to occur. TGF adaptation is mechanistically coupled to the end point targeted by chronic deviations in MD NaCl, the rate of local and systemic angiotensin II generation. MD control of renin secretion is the result of the coordinated action of local mediators that include nitric oxide synthase (NOS) and cyclooxygenase (COX) products. Thus vascular smooth muscle cell activation during high MD transport and granular cell activation during low MD transport is achieved by different extracellular mediators. The coordinated regulation of NOS I and COX-2 expression in MD cells and of renin expression in granular cells suggests that control of juxtaglomerular regulation of gene transcription or mRNA metabolism may be another consequence of a chronic alteration in MD NaCl concentration.
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Mika, D., W. Richter, R. E. Westenbroek, W. A. Catterall, and M. Conti. "PDE4B mediates local feedback regulation of 1-adrenergic cAMP signaling in a sarcolemmal compartment of cardiac myocytes." Journal of Cell Science 127, no. 5 (January 10, 2014): 1033–42. http://dx.doi.org/10.1242/jcs.140251.
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Einer-Jensen, N., and RHF Hunter. "Counter-current transfer in reproductive biology." Reproduction 129, no. 1 (January 2005): 9–18. http://dx.doi.org/10.1530/rep.1.00278.
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Heat and substances, including gases, steroids and peptide hormones, can pass from venous blood, interstitial fluid and lymph to the arterial blood; the process is called local counter-current transfer. It has been found in various reproductive organs in many animal species and in man: from the testis to the testis and epididymis; from the ovary to the ovary, tube and tubal corner of the uterus; from the tube and uterus to the ovary; from vagina to uterus; and even between brain blood vessels. Local transfer within the ovary has also been found. Local cooling that creates temperature gradients between organs or within an organ is one aspect of the transfer. Physiologically, the transfer also facilitates local feedback regulation of organ function in a process situated between general distribution of hormones through the systemic circulation and paracrine regulation. Counter-current transfer of drugs after local application opens up new possibilities for treatment.
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Saravanan, Surat, C. Meghana, and Maithreyi Narasimha. "Local, cell-nonautonomous feedback regulation of myosin dynamics patterns transitions in cell behavior: a role for tension and geometry?" Molecular Biology of the Cell 24, no. 15 (August 2013): 2350–61. http://dx.doi.org/10.1091/mbc.e12-12-0868.
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How robust patterns of tissue dynamics emerge from heterogeneities, stochasticities, and asynchronies in cell behavior is an outstanding question in morphogenesis. A clear understanding of this requires examining the influence of the behavior of single cells on tissue patterning. Here we develop single-cell manipulation strategies to uncover the origin of patterned cell behavior in the amnioserosa during Drosophila dorsal closure. We show that the formation and dissolution of contractile, medial actomyosin networks previously shown to underlie pulsed apical constrictions in the amnioserosa are apparently asynchronous in adjacent cells. We demonstrate for the first time that mechanical stresses and Rho1 GTPase control myosin dynamics qualitatively and quantitatively, in amplitude and direction, both cell autonomously and nonautonomously. We then demonstrate that interfering with myosin-dependent contractility in single cells also influences pulsed constrictions cell nonautonomously. Our results suggest that signals and stresses can feedback regulate the amplitude and spatial propagation of pulsed constrictions through their influence on tension and geometry. We establish the relevance of these findings to native closure by showing that cell delamination represents a locally patterned and collective transition from pulsed to unpulsed constriction that also relies on the nonautonomous feedback control of myosin dynamics.
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Boyer, Laurent, Christophe Lançon, Karine Baumstarck, Nathalie Parola, Julie Berbis, and Pascal Auquier. "Evaluating the impact of a quality of life assessment with feedback to clinicians in patients with schizophrenia: randomised controlled trial." British Journal of Psychiatry 202, no. 6 (June 2013): 447–53. http://dx.doi.org/10.1192/bjp.bp.112.123463.
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BackgroundQuality of life (QoL) measurements are increasingly considered to be an important evaluation of the treatment and care provided to patients with schizophrenia. However, there is little evidence that assessing QoL improves patient outcomes in clinical practice.AimsTo investigate the impact of a QoL assessment with feedback for clinicians regarding satisfaction and other health outcomes in patients with schizophrenia.MethodWe conducted a 6-month, prospective, randomised and controlled open-label study. Patients withschizophrenia were assigned to one of three groups: standard psychiatric assessment; QoL assessment with standard psychiatric assessment; and QoL feedback with standard psychiatric assessment. The primary outcome was patient satisfaction at 6 months. The local ethics committee (Comité de Protection des Personnes Sud-Métediterranéee V, France, trial number 07 067) and the French drug and device regulation agency (Agence Française de Sécurité Sanitaire des Produits de Santé, France, trial number A01033-50) approved this study.ResultsWe randomly assigned 124 patients into groups. Quality of life feedback significantly affectedpatient satisfaction. Global satisfaction was significantly higher in the QoL feedback group (72.5% of patients had a high level of satisfaction) compared with the standard psychiatric assessment (67.5%) and QoL assessment groups (45.2%). Despite trends towards decreased severity for all clinical outcomes and increased changes to medication in the QoL feedback group at 6-month follow-up, these effects were not significant.ConclusionsQuality of life feedback positively influences patient satisfaction, which confirms the relevance of measuring QoL in clinical practice. The absence of a significant effect of QoL feedbackon clinical outcomes also suggests that clinicians did not use these data optimally. Our findings suggest a nocebo effect of QoL assessment without feedback that should be considered by researchers and clinicians.
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McClamroch, H., and D. Wang. "Linear Feedback Control of Position and Contact Force for a Nonlinear Constrained Mechanism." Journal of Dynamic Systems, Measurement, and Control 112, no. 4 (December 1, 1990): 640–45. http://dx.doi.org/10.1115/1.2896189.
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A feedback control problem for a constrained mechanism is formulated and solved. The mechanism is controlled by forces applied to the mechanism which are to be adjusted according to a linear control law, based on feedback of the positions and velocities of the mechanism and feedback of the constraint force on the mechanism. The control objective is to achieve accurate and robust local regulation of the motion of the mechanism and of the constraint force on the mechanism. Derivation of a suitable control law is significantly complicated by the nonclassical nature of the differential-algebraic model of the constrained system and by the nonlinear characteristics of the model. The control design approach involves use of a certain nonlinear transformation which leads to a set of decoupled differential-algebraic equations; classical control design methodology can be applied to these latter equations. An example of a planar mechanism is studied in some detail, for two different regulation objectives. Specific control laws are developed using the described methodology. Comparisons are made with a closed loop system, where the control law is derived without proper consideration of the constraint force. Computer simulations are presented to demonstrate the several closed-loop properties.
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Wood, Paul L. "Pharmacological evaluation of GABAergic and glutamatergic inputs to the nucleus basalis–cortical and the septal–hippocampal cholinergic projections." Canadian Journal of Physiology and Pharmacology 64, no. 3 (March 1, 1986): 325–28. http://dx.doi.org/10.1139/y86-053.
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The presence of different receptor populations within a given brain area can be effectively evaluated via the local injections of defined receptor agonists and antagonists. Using this approach, it has become evident that the nucleus basalis – cortical cholinergic pathway possesses an inhibitory GABAergic input to the nucleus basalis from the nucleus accumbens as well as a positive glutamatergic feedback from the cortex. The septal–hippocampal cholinergic pathway also possesses an inhibitory GABAergic regulation which consists of a large GABAergic interneuron population in the septum. A glutamatergic feedback from the hippocampus is also present. These regulatory inputs to cholinergic cells are not tonically active but appear to function as phasic modulators of cholinergic transmission in both pathways.
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Jonsson, Amanda, Sahika Inal, Ilke Uguz, Adam J. Williamson, Loïg Kergoat, Jonathan Rivnay, Dion Khodagholy, et al. "Bioelectronic neural pixel: Chemical stimulation and electrical sensing at the same site." Proceedings of the National Academy of Sciences 113, no. 34 (August 9, 2016): 9440–45. http://dx.doi.org/10.1073/pnas.1604231113.
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Local control of neuronal activity is central to many therapeutic strategies aiming to treat neurological disorders. Arguably, the best solution would make use of endogenous highly localized and specialized regulatory mechanisms of neuronal activity, and an ideal therapeutic technology should sense activity and deliver endogenous molecules at the same site for the most efficient feedback regulation. Here, we address this challenge with an organic electronic multifunctional device that is capable of chemical stimulation and electrical sensing at the same site, at the single-cell scale. Conducting polymer electrodes recorded epileptiform discharges induced in mouse hippocampal preparation. The inhibitory neurotransmitter, γ-aminobutyric acid (GABA), was then actively delivered through the recording electrodes via organic electronic ion pump technology. GABA delivery stopped epileptiform activity, recorded simultaneously and colocally. This multifunctional “neural pixel” creates a range of opportunities, including implantable therapeutic devices with automated feedback, where locally recorded signals regulate local release of specific therapeutic agents.
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Syarifudin, Amin, and Rakhmat Bowo Suharto. "Analysis Juridical Public Participation Formation of Regional Regulation No. 3 of 2017 on The Implementation of The Business Entertainment In Wonosobo Regency." Jurnal Daulat Hukum 2, no. 1 (March 20, 2019): 147. http://dx.doi.org/10.30659/jdh.v2i1.4268.
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To set the order and comfort in the Wonosobo regency and Goverment Wonosobo regency make Region Regulation No. 3 of 2017 on the Implementation of Enterprise Entertainment in Wonosobo. This is associated with the rise of karaoke business premises in Wonosobo. But after the regulation passes reap a lot of conflict in the community. This makes the writer interested in making. Juridical Analysis of Public Participation in Formation of Regional Regulation Number. 3 of 2017 on the Implementation of Enterprise Entertainment in Wonosobo,Method of approach used in this study is a sociological juridical methods, using the principles and legal principles in reviewing, view, and analyze problems.According to Act No. 12 of 2011 Establishment Regulation Legislation. Article 96 "The public has the right to give feedback in oral and / or written in question can be done through public hearings, working visits, socialization and / or, seminars, workshops and / or discussion.In the establishment of the Regional Regulation No. 3 Of 2017 on the Implementation of Enterprise Entertainment in Wonosobo regency public participation, not maximum.Constraints in the face is the lack of public interest in participating, goverment is valued less the aspirations of the people should be overcome by it, provide an understanding of the importance of public participation in Formation of Regional Regulation 3 Of 2017 about the entertainment business in Wonosobo, maximizing the dissemination of the regulations and the third accommodate all the aspirations of the peopleKeywords: Public Participation; Local Regulation; Entertainment.
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Hughson, Richard L. "Regulation of Blood Flow at the Onset of Exercise by Feed Forward and Feedback Mechanisms." Canadian Journal of Applied Physiology 28, no. 5 (October 1, 2003): 774–87. http://dx.doi.org/10.1139/h03-058.
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Blood flow adapts quickly after the onset of exercise to meet the metabolic demands of skeletal muscle. This review approaches the issue of how rapidly blood flow adapts and what the mechanisms for adaptation are primarily from a control theory perspective. Several recent papers have suggested that O2 transport proceeds at a rate that anticipates the metabolic demand over a very wide range of work rates. When considered from a control theory perspective, this implies involvement of feed forward control. Although there is one very important feed forward mechanism in the muscle pump that is activated with the onset of exercise, other evidence suggests that adjustment of blood flow to match the metabolic demand relies on feedback control from local dilator factors released in proportion to the metabolic demand. These distinct mechanisms with different onset times mean that blood flow adapts to the exercise demand with at least two distinct phases. The time course of the adaptation varies greatly between work rates, showing that blood flow control cannot be described by a linear control system and that the mechanisms responsible for vasodilation are dependent on work rate. Key words: oxygen uptake, kinetics, vasodilation, muscle metabolism
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BEN-JACOB, ESHEL, OFER SHOCHET, ADAM TENENBAUM, INON COHEN, ANDRAS CZIRÓK, and TAMÁS VICSEK. "COMMUNICATION, REGULATION AND CONTROL DURING COMPLEX PATTERNING OF BACTERIAL COLONIES." Fractals 02, no. 01 (March 1994): 15–44. http://dx.doi.org/10.1142/s0218348x9400003x.
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We present a study of interfacial pattern formation during growth of bacterial colonies. Growth of bacterial colony bears similarities to but presents an inherent additional level of complexity compared to non-living systems. In the former case, the building blocks themselves are living systems each with its own autonomous self-interest and internal degrees of freedom. At the same time, efficient adaptation of the colony to adverse growth conditions requires self-organization on all levels — which can be achieved only via cooperative behavior of the bacteria. To do so, the bacteria have developed sophisticated communication channels on all levels. Here we present a non-local communicating walkers model to study the effect of local bacterium-bacterium interaction and communication via chemotaxis signaling. We demonstrate how communication enables the colony to develop complex patterns in response to adverse growth conditions. Efficient response of the colony requires self-organization on all levels, which can be achieved only via cooperative behavior of the bacteria. It can be viewed as the action of an interplay between the micro-level (the individual bacterium) and the macro-level (the colony) in the determination of the emerging pattern. Some qualitative features of the complex morphologies can be accounted for by invoking ideas from pattern formation in non-living systems together with a simplified model of chemotactic "feedback."
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Zhao, Guiling, Humberto C. Joca, Mark T. Nelson, and W. Jonathan Lederer. "ATP- and voltage-dependent electro-metabolic signaling regulates blood flow in heart." Proceedings of the National Academy of Sciences 117, no. 13 (March 13, 2020): 7461–70. http://dx.doi.org/10.1073/pnas.1922095117.
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Local control of blood flow in the heart is important yet poorly understood. Here we show that ATP-sensitive K+ channels (KATP), hugely abundant in cardiac ventricular myocytes, sense the local myocyte metabolic state and communicate a negative feedback signal-correction upstream electrically. This electro-metabolic voltage signal is transmitted instantaneously to cellular elements in the neighboring microvascular network through gap junctions, where it regulates contractile pericytes and smooth muscle cells and thus blood flow. As myocyte ATP is consumed in excess of production, [ATP]i decreases to increase the openings of KATP channels, which biases the electrically active myocytes in the hyperpolarization (negative) direction. This change leads to relative hyperpolarization of the electrically connected cells that include capillary endothelial cells, pericytes, and vascular smooth muscle cells. Such hyperpolarization decreases pericyte and vascular smooth muscle [Ca2+]i levels, thereby relaxing the contractile cells to increase local blood flow and delivery of nutrients to the local cardiac myocytes and to augment ATP production by their mitochondria. Our findings demonstrate the pivotal roles of local cardiac myocyte metabolism and KATP channels and the minor role of inward rectifier K+ (Kir2.1) channels in regulating blood flow in the heart. These findings establish a conceptually new framework for understanding the hugely reliable and incredibly robust local electro-metabolic microvascular regulation of blood flow in heart.
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Zhou, Hong, Xinyan Wang, Wendy K. W. Ko, and Anderson O. L. Wong. "Evidence for a Novel Intrapituitary Autocrine/Paracrine Feedback Loop Regulating Growth Hormone Synthesis and Secretion in Grass Carp Pituitary Cells by Functional Interactions between Gonadotrophs and Somatotrophs." Endocrinology 145, no. 12 (December 1, 2004): 5548–59. http://dx.doi.org/10.1210/en.2004-0362.
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Abstract Gonadotropin (GTH) and GH released from the pituitary are known to interact at multiple levels to modulate the functions of the gonadotrophic and somatotrophic axes. However, their interactions at the pituitary level have not been fully characterized. In this study, autocrine/paracrine regulation of GH synthesis and secretion by local interactions between gonadotrophs and somatotrophs was examined using grass carp pituitary cells as a cell model. Exogenous GTH and GH induced GH release and GH mRNA expression in carp pituitary cells. Removal of endogenous GTH and GH by immunoneutralization with GTH and GH antisera, respectively, suppressed GH release, GH production, and GH mRNA levels. GH antiserum also blocked the stimulatory effects of exogenous GTH on GH release and GH mRNA levels. In reciprocal experiments, GH release and GH mRNA expression induced by exogenous GH was significantly reduced by GTH antiserum. In addition, exogenous GH was found to be inhibitory to basal GTH release and treatment with GH antiserum elevated GTH secretion at low doses but suppressed GTH production at high doses. These results suggest that local interactions between gonadotrophs and somatotrophs may form an intrapituitary feedback loop to regulate GH release and synthesis. In this model, GTH released from gonadotrophs induces GH release and GH production in neighboring somatotrophs. GH secreted maintains somatotroph sensitivity to GTH stimulation, and at the same time, inhibits basal GTH release in gonadotrophs. This feedback loop may represent a novel mechanism regulating GH release and synthesis in lower vertebrates.
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Korayem, M. H., H. Tourajizadeh, A. Zehfroosh, and A. H. Korayem. "Optimal regulation of a cable robot in presence of obstacle using optimal adaptive feedback linearization approach." Robotica 33, no. 4 (March 21, 2014): 933–52. http://dx.doi.org/10.1017/s0263574714000691.
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SUMMARYOptimal path planning of a closed loop cable robot, between two predefined points in presence of obstacles is the goal of this paper. This target is met by proposing a new method of optimal regulation for non linear systems while Dynamic Load Carrying Capacity (DLCC) of the robot is supposed as the related cost function. Feedback linearization is used to linearize the system while Linear Quadratic Regulator (LQR) is employed to optimize the DLCC of the system based on torque and error constraints. Obstacle avoidance for both the end-effector and cables is also considered by the aid of designing an adaptive local obstacle avoidance controller. As a result of linearized nature of the proposed optimal regulation and obstacle avoidance, fast calculation for real time applications is possible. Therefore, formulation of the optimal feedback linearization, together with calculating the DLCC of the robot based on the presented constraints is derived. Finally, a simulation study is performed to study the optimal dynamics and also the maximum DLCC of the cable robot in presence of obstacles. Simulation results are eventually compared with experimental tests conducted on IUST Cable Suspended Robot (ICaSbot) to verify the validity and efficiency of the proposed optimal controllers.
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Ludwig, M. "Functional role of intrahypothalamic release of oxytocin and vasopressin: consequences and controversies." American Journal of Physiology-Endocrinology and Metabolism 268, no. 4 (April 1, 1995): E537—E545. http://dx.doi.org/10.1152/ajpendo.1995.268.4.e537.
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This brief review of vasopressin (VP) and oxytocin (OT) release into the extracellular space of the supraoptic (SON) and paraventricular (PVN) nuclei focuses on recent data illustrating the significance of their intranuclear release and the potential functional consequences. With the use of in vitro techniques, it has been demonstrated that administration of exogenous OT causes local peptide release and that, in vivo, this facilitates the milk ejection reflex. These findings lead to the idea that endogenous peptides are released into the hypothalamic nuclei. Microperfusion techniques have been used to monitor the dynamics of intranuclear OT and VP release in response to distinct stimuli. It is clear that intranuclear release of OT plays a role during reproductive states (parturition and lactation) and that intranuclear release of VP and OT is involved in osmoregulation. This review discusses 1) the origin of the intranuclearly released peptides, 2) stimuli which cause release into the hypothalamic nuclei, and 3) the function of intranuclear VP and OT, e.g., regulation of local morphology, feedback mechanisms and synchronization, and the possible role in regulating autonomic function and behavior.
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Zheng, Yunhua, Jin Bai, Mulan He, and Anderson O. L. Wong. "Functional Interaction of Spexin and Adiponectin Forming a Local Feedbackin Goldfish Hepatocytes for Feeding Regulation." Journal of the Endocrine Society 5, Supplement_1 (May 1, 2021): A47. http://dx.doi.org/10.1210/jendso/bvab048.093.
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Abstract Spexin (SPX), a neuropeptide with pleiotropic functions, has been confirmed to be a novel satiety factor in fish models. Adiponectin (AdipoQ), the most abundant adipokine in circulation, is involved in lipid and glucose metabolism and its insulin-sensitizing, cardioprotective, and anti-inflammatory actions are also well-documented. However, the interaction between SPX and AdipoQ has not be reported and very little is known regarding the functions of AdipoQ in non-mammalian species. In this study, AdipoQ was cloned in goldfish and found to be widely expressed at tissue level including the liver. Sequence alignment and in silico protein modelling revealed that its a.a. sequence and 3D protein structure were highly comparable to the mammalian counterparts. Recombinant protein of goldfish AdipoQ was expressed in E. coli and IP injection of the protein purified could suppress foraging activity and food intake in goldfish. Food intake in goldfish, interestingly, could elevate plasma levels of SPX and AdipoQ with parallel rises of their transcript expression in the liver. In primary culture of goldfish hepatocytes, SPX treatment was shown to induce protein phosphorylation of MEK1/2 and ERK1/2 with a parallel rise in AdipoQ mRNA level. SPX-induced AdipoQ mRNA expression, however, was sensitive to the blockade of PLC/PKC, Ca2+/CaMK-II and MEK1/2/ERK1/2 but not cAMP/PKA cascades. In reciprocal experiments, AdipoQ treatment could induce protein phosphorylation of AMPK, Akt and P38 MAPK in goldfish hepatocytes. Meanwhile, AdipoQ was also effective in reducing SPX mRNA level and this inhibitory effect was negated by blocking the AMPK/PPAR, PI3K/Akt and P38 MAPK but not the MEK1/2/ERK1/2 or PLC/PKC pathways. Apparently, the PI3K/Akt and P38 MAPK cascades were functionally coupled with AMPK activation. These results imply that (i) AdipoQ, similar to SPX, can be induced by food intake and serve as a satiety signal in goldfish, (ii) AdipoQ expression in goldfish liver can be up-regulated by SPX via the PLC/PKC, Ca2+/CaMK-II and MEK1/2/ERK1/2 pathways, which may enhance the satiation response caused by SPX after food intake, and (iii) AdipoQ can inhibit SPX expression at hepatic level via the AMPK/PPAR, PI3K/Akt and P38 MAPK cascades, which may lead to signal termination of SPX. These findings, as a whole, suggest that AdipoQ production in goldfish liver not only can form a signal amplification step for the satiation response of SPX but also constitute a local feedback to turn off SPX signal at the hepatic level.
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Fan, Ying, Gonzalo Miguez-Macho, Esteban G. Jobbágy, Robert B. Jackson, and Carlos Otero-Casal. "Hydrologic regulation of plant rooting depth." Proceedings of the National Academy of Sciences 114, no. 40 (September 18, 2017): 10572–77. http://dx.doi.org/10.1073/pnas.1712381114.
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Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here, we present a global synthesis of 2,200 root observations of >1,000 species along biotic (life form, genus) and abiotic (precipitation, soil, drainage) gradients. Results reveal strong sensitivities of rooting depth to local soil water profiles determined by precipitation infiltration depth from the top (reflecting climate and soil), and groundwater table depth from below (reflecting topography-driven land drainage). In well-drained uplands, rooting depth follows infiltration depth; in waterlogged lowlands, roots stay shallow, avoiding oxygen stress below the water table; in between, high productivity and drought can send roots many meters down to the groundwater capillary fringe. This framework explains the contrasting rooting depths observed under the same climate for the same species but at distinct topographic positions. We assess the global significance of these hydrologic mechanisms by estimating root water-uptake depths using an inverse model, based on observed productivity and atmosphere, at 30″ (∼1-km) global grids to capture the topography critical to soil hydrology. The resulting patterns of plant rooting depth bear a strong topographic and hydrologic signature at landscape to global scales. They underscore a fundamental plant–water feedback pathway that may be critical to understanding plant-mediated global change.
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Lucy, Matthew C. "Growth hormone regulation of follicular growth." Reproduction, Fertility and Development 24, no. 1 (2012): 19. http://dx.doi.org/10.1071/rd11903.
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The somatotropic axis – consisting of growth hormone (GH), the insulin-like growth factors 1 and 2 (IGF1 and IGF2), GH binding protein (GHBP), IGF binding proteins (IGFBPs) 1 to 6, and the cell-surface receptors for GH and the IGFs – has major effects on growth, lactation and reproduction. The primary target tissues for GH are involved in growth and metabolism. The functionality of the somatotropic axis depends in part on the expression of liver GH receptor (GHR), which determines the amount of IGF1 released from the liver in response to GH. The IGF1 acts as a pleiotropic growth factor and also serves as the endocrine negative feedback signal controlling pituitary GH secretion. Growth hormone and IGF1 undergo dynamic changes throughout the life cycle, particularly when animals are either growing, early post partum or lactating. Cells within the reproductive tract can respond directly to GH but to a lesser degree than the primary target tissues. The major impact that GH has on reproduction, therefore, may be secondary to its systemic effects on metabolism (including insulin sensitivity) or secondary to the capacity for GH to control IGF1 secretion. Insulin-like growth factor 1 and IGFBP are also synthesised within the ovary and this local synthesis is a component of the collective IGF1 action on the follicle. Future studies of GH should focus on its direct effects on the follicle as well as its indirect effects mediated by shifts in nutrient metabolism, insulin sensitivity, IGF1 and IGFBP.
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Jaggar, Jonathan H., Valerie A. Porter, W. Jonathan Lederer, and Mark T. Nelson. "Calcium sparks in smooth muscle." American Journal of Physiology-Cell Physiology 278, no. 2 (February 1, 2000): C235—C256. http://dx.doi.org/10.1152/ajpcell.2000.278.2.c235.
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Local intracellular Ca2+transients, termed Ca2+ sparks, are caused by the coordinated opening of a cluster of ryanodine-sensitive Ca2+ release channels in the sarcoplasmic reticulum of smooth muscle cells. Ca2+ sparks are activated by Ca2+ entry through dihydropyridine-sensitive voltage-dependent Ca2+ channels, although the precise mechanisms of communication of Ca2+ entry to Ca2+ spark activation are not clear in smooth muscle. Ca2+ sparks act as a positive-feedback element to increase smooth muscle contractility, directly by contributing to the global cytoplasmic Ca2+ concentration ([Ca2+]) and indirectly by increasing Ca2+ entry through membrane potential depolarization, caused by activation of Ca2+ spark-activated Cl− channels. Ca2+ sparks also have a profound negative-feedback effect on contractility by decreasing Ca2+ entry through membrane potential hyperpolarization, caused by activation of large-conductance, Ca2+-sensitive K+ channels. In this review, the roles of Ca2+sparks in positive- and negative-feedback regulation of smooth muscle function are explored. We also propose that frequency and amplitude modulation of Ca2+ sparks by contractile and relaxant agents is an important mechanism to regulate smooth muscle function.
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Feng, Xiaoping, Di Lu, and Siyu Feng. "Practical Dilemma and Path Innovation of Social Governance: A Case Study of Land Expropriation in China." E3S Web of Conferences 235 (2021): 02072. http://dx.doi.org/10.1051/e3sconf/202123502072.
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In the “Internet+” era, conflicts of land requisition frequently occur. Existing research emphasizes the lack of systems but rarely considers the problems in the implementation of the system. Based on “Internet+”, this article adopts a case analysis method to discuss the governance of land requisition conflicts. This study analyzes the contradictions in the implementation of land acquisition, benefit distribution, procedures and information feedback. The dilemma of social governance stems from the “autonomous space”, “three-dimensional competition” and “independent space” of local governments. The innovation path of social governance needs to emphasize the supervision and regulation in the implementation of the system, the optimization of the system and the setting of the system and the flexible setting of the local field.
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Cheng, Gheorghe F. Y., Chi-Wai Yuen, and Wei Ge. "Evidence for the existence of a local activin–follistatin negative feedback loop in the goldfish pituitary and its regulation by activin and gonadal steroids." Journal of Endocrinology 195, no. 3 (September 25, 2007): 373–84. http://dx.doi.org/10.1677/joe-07-0265.
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Activin is an important regulator of gonadotropin expression and production in the vertebrate pituitary, and its activity is fine-tuned by its binding protein follistatin. In the present study, a full-length cDNA for follistatin was cloned in the goldfish, which shows 74% amino acid sequence identity with that of mammals. Recombinant goldfish follistatin expressed in the Chinese hamster ovary cells significantly blocked activin-induced F5-5 cell differentiation. Goldfish follistatin is expressed in a wide range of tissues including the brain, pituitary, ovary, and testis. The expression of follistatin mRNA in the pituitary is regulated by both activin and gonadal steroids in vitro. Treatment with goldfish activin B for 48 h significantly up-regulated follistatin expression in cultured pituitary cells, suggesting a closed activin–follistatin feedback loop in the pituitary. In agreement with this, both human and goldfish follistatin down-regulated the expression of follistatin itself, probably due to the neutralization of endogenous activin. Examination of FSHβ and LHβ expression in the same samples supports the role of activin and follistatin in the differential regulation of FSH and LH as demonstrated previously. Since the expression level of activin βB in the pituitary is rather stable both in vitro and in vivo, it is conceivable that follistatin may play a pivotal regulatory role in the intra-pituitary activin system. Both estradiol and testosterone up-regulated follistatin expression in vitro, suggesting a mediating role for follistatin in steroid feedback on pituitary hormones. These results provide clues to the potential physiological roles of activin–follistatin system in the regulation of gonadotropin biosynthesis in teleosts.
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Nafz, B., P. B. Persson, H. Ehmke, and H. R. Kirchheim. "A servo-control system for open- and closed-loop blood pressure regulation." American Journal of Physiology-Renal Physiology 262, no. 2 (February 1, 1992): F320—F325. http://dx.doi.org/10.1152/ajprenal.1992.262.2.f320.
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An electropneumatic servo-control system is described that can reduce and control arterial blood pressure in experimental animals. The device has been proved useful in the analysis of pressure-dependent physiological processes and allows the following two modes of operation: 1) a conventional open-loop setting that will reduce arterial pressure to a preselected set point and 2) a closed-loop mode that enables an adjustment to a dynamic pressure set point (i.e., the controlled pressure is reduced to a constant value below a reference pressure). A pneumatic servo-control mechanism was chosen to provide minimal control latency. The accuracy of the system under physiological conditions is well within +/- 1 mmHg. The device can be useful in a number of studies demanding a precise regulation of local arterial pressure, such as experiments on blood flow autoregulation, arterial baroreceptor reflexes, and all experiments involving the study of pressure-dependent excretory and incretory functions of the kidney. The closed-loop setting is useful for studying physiological feedback systems.
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Sane, Sanjay P., Robert B. Srygley, and Robert Dudley. "Antennal regulation of migratory flight in the neotropical moth Urania fulgens." Biology Letters 6, no. 3 (January 24, 2010): 406–9. http://dx.doi.org/10.1098/rsbl.2009.1073.
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Migrating insects use their sensory systems to acquire local and global cues about their surroundings. Previous research on tethered insects suggests that, in addition to vision and cephalic bristles, insects use antennal mechanosensory feedback to maintain their airspeeds. Owing to the large displacements of migratory insects and difficulties inherent in tracking single individuals, the roles of these sensory inputs have never been tested in freely migrating insects. We tracked individual uraniid moths ( Urania fulgens ) as they migrated diurnally over the Panama Canal, and measured airspeeds and orientation for individuals with either intact or amputated flagella. Consistent with prior observations that antennal input is necessary for flight control, 59 per cent of the experimental moths could not fly after flagella amputation. The remaining fraction (41%) was flight-capable and maintained its prior airspeeds despite severe reduction in antennal input. Thus, maintenance of airspeeds may not involve antennal input alone, and is probably mediated by other modalities. Moths with amputated flagella could not recover their proper migratory orientations, suggesting that antennal integrity is necessary for long-distance navigation.
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Wilde, C. J., C. V. P. Addey, F. M. Campbell, S. A. Connor, M. A. Kerr, and C. H. Knight. "Autocrine control of milk secretion by a milk protein." Proceedings of the British Society of Animal Production (1972) 1993 (March 1993): 159. http://dx.doi.org/10.1017/s0308229600024831.
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The rate of milk secretion is controlled acutely by the frequency and completeness of milk removal from the mammary gland. Numerous experiments in dairy animals have shown that this acute control is exerted locally within each gland, rather than by circulating galactopoietic hormones (Wilde & Peaker, 1990). Local regulation of milk secretion by milk removal is not related to physical distension of the gland by accumulated milk (Henderson & Peaker, 1984), but is instead the result of changes in the degree of chemical feedback inhibition exerted by a secreted milk constituent.Proteins that may act as feedback inhibitors of lactation (FIL) have been isolated from goat's milk (Addey et al, 1991a), cow's milk (Addey et al, 1991b) and human milk (Wilde, unpublished work) on the basis of their ability to inhibit synthesis of milk constituents in a rabbit tissue explant bioassay (Wilde et al, 1987a).
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Doulgeri, Zoe, and Yiannis Karayiannidis. "Force/position control self-tuned to unknown surface slopes using motion variables." Robotica 26, no. 6 (November 2008): 703–10. http://dx.doi.org/10.1017/s026357470800430x.
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SUMMARYThis work considers the problem of force/position regulation for a robotic finger in compliant contact with an unknown curved surface resulting in uncertain force and position control subspaces. The proposed controller is an adaptive control scheme of a simple structure that achieves the desired target by the on-line tuning of the position and force control actions to their corresponding actual subspaces at the desired point using motion state feedback. The local asymptotic stability of the system equilibrium point is proved and an estimate of the region of attraction is given. The controller performance is illustrated by a simulation example.
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Callewaert, G., R. G. Johnson, and M. Morad. "Regulation of the secretory response in bovine chromaffin cells." American Journal of Physiology-Cell Physiology 260, no. 4 (April 1, 1991): C851—C860. http://dx.doi.org/10.1152/ajpcell.1991.260.4.c851.
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The nicotine-induced current and the Ca2+ current were studied in cultured bovine chromaffin cells using the whole cell patch-clamp technique. The dose-response curve for the nicotinic current gave a dissociation constant of 53 microM and a Hill coefficient of 1.3. Desensitization of the nicotinic current was rapid, with time constants of 22 and 155 ms at 10 microM nicotine. At higher concentrations of nicotine, both time constants decreased somewhat, but the most prominent effect was on the ratio of the two components. Recovery from desensitization was fitted by a single exponential with a time constant of approximately 6 s. Ca2+ current and catecholamine secretion were highly sensitive to changes in extracellular H+ concentration ([H+]o), such that small increases in [H+]o markedly decreased both. The Ca2+ current measured in a chromaffin cell located within a cluster of cells, but not in a single isolated cell, was markedly suppressed when KCl or nicotine was used to induce secretion, suggesting possible local feedback of secretory agents. Among agents secreted by chromaffin cells, ATP, enkephalins, epinephrine, and protons, only protons significantly suppressed the Ca2+ current. Our findings suggest that the secretory response of chromaffin cells may be modulated by rapid desensitization of the nicotinic receptor and a secretion-dependent suppression of the Ca2+ current.
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Tepper, Sandra, Oliver Mortusewicz, Ewelina Członka, Amanda Bello, Angelika Schmidt, Julia Jeschke, Arthur Fischbach, et al. "Restriction of AID activity and somatic hypermutation by PARP-1." Nucleic Acids Research 47, no. 14 (May 25, 2019): 7418–29. http://dx.doi.org/10.1093/nar/gkz466.
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Abstract Affinity maturation of the humoral immune response depends on somatic hypermutation (SHM) of immunoglobulin (Ig) genes, which is initiated by targeted lesion introduction by activation-induced deaminase (AID), followed by error-prone DNA repair. Stringent regulation of this process is essential to prevent genetic instability, but no negative feedback control has been identified to date. Here we show that poly(ADP-ribose) polymerase-1 (PARP-1) is a key factor restricting AID activity during somatic hypermutation. Poly(ADP-ribose) (PAR) chains formed at DNA breaks trigger AID-PAR association, thus preventing excessive DNA damage induction at sites of AID action. Accordingly, AID activity and somatic hypermutation at the Ig variable region is decreased by PARP-1 activity. In addition, PARP-1 regulates DNA lesion processing by affecting strand biased A:T mutagenesis. Our study establishes a novel function of the ancestral genome maintenance factor PARP-1 as a critical local feedback regulator of both AID activity and DNA repair during Ig gene diversification.
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Xing, Jichun, Huajun Li, and Dechun Liu. "Anisotropic Vibration Tactile Model and Human Factor Analysis for a Piezoelectric Tactile Feedback Device." Micromachines 10, no. 7 (July 3, 2019): 448. http://dx.doi.org/10.3390/mi10070448.
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Tactile feedback technology has important development prospects in interactive technology. In order to enrich the tactile sense of haptic devices under simple control, a piezoelectric haptic feedback device is proposed. The piezoelectric tactile feedback device can realize tactile changes in different excitation voltage amplitudes, different excitation frequencies, and different directions through the ciliary body structure. The principle of the anisotropic vibration of the ciliary body structure was analyzed here, and a tactile model was established. The equivalent friction coefficient under full-coverage and local-coverage of the skin of the touch beam was deduced and solved. The effect of system parameters on the friction coefficient was analyzed. The results showed that in the full-coverage, the tactile effect is mainly affected by the proportion of the same directional ciliary bodies and the excitation frequency. The larger the proportion of the same direction ciliary body is, the smaller the coefficient of friction is. The larger the excitation frequency is, the greater the coefficient of friction is. In the local-coverage, the tactile effect is mainly affected by the touch position and voltage amplitude. When changing the touch pressure, it has a certain effect on the change of touch, but it is relatively weak. The experiment on the sliding friction of a cantilever touch beam and the experiment of human factor were conducted. The experimental results of the sliding friction experiment are basically consistent with the theoretical calculations. In the human factor experiment, the effects of haptic regulation are mainly affected by voltage or structure of the ciliary bodies.
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Han, Renke, Qiuye Sun, Dazhong Ma, and Bonan Huang. "Modeling Single-Phase Inverter and Its Decentralized Coordinated Control by Using Feedback Linearization." Mathematical Problems in Engineering 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/581323.
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It is a very crucial problem to make a microgrid operated reasonably and stably. Considering the nonlinear mathematics model of inverter established in this paper, the input-output feedback linearization method is used to transform the nonlinear mathematics model of inverters to a linear tracking synchronization and consensus regulation control problem. Based on the linear mathematics model and multiagent consensus algorithm, a decentralized coordinated controller is proposed to make amplitudes and angles of voltages from inverters be consensus and active and reactive power shared in the desired ratio. The proposed control is totally distributed because each inverter only requires local and one neighbor’s information with sparse communication structure based on multiagent system. The hybrid consensus algorithm is used to keep the amplitude of the output voltages following the leader and the angles of output voltage as consensus. Then the microgrid can be operated more efficiently and the circulating current between DGs can be effectively suppressed. The effectiveness of the proposed method is proved through simulation results of a typical microgrid system.
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Malpel, S., C. Mendelsohn, and W. V. Cardoso. "Regulation of retinoic acid signaling during lung morphogenesis." Development 127, no. 14 (July 15, 2000): 3057–67. http://dx.doi.org/10.1242/dev.127.14.3057.
Full textAbstract:
Little is known about how retinoic acid (RA) synthesis, utilization and metabolism are regulated in the embryonic lung and how these activities relate to lung pattern formation. Here we report that early lung bud formation and subsequent branching morphogenesis are characterized by distinct stages of RA signaling. At the onset of lung development RA signaling is ubiquitously activated in primary buds, as shown by expression of the major RA-synthesizing enzyme, RALDH-2 and activation of a RARE-lacZ transgene. Nevertheless, further airway branching appears to require downregulation of RA pathways by decreased synthesis, increased RA degradation in the epithelium via P450RAI-mediated metabolism, and inhibition of RA signaling in the mesenchyme by COUPTF-II expression. These mechanisms controlling local RA signaling may be critical for normal branching, since we show that manipulating RA levels in vitro to maintain RA signaling activated as in the initial stage, leads to an immature lung phenotype characterized by failure to form typical distal buds. We show that this phenotype likely results from RA interfering with the establishment of a distal signaling center, altering levels and distribution of Fgf10 and Bmp4, genes that are essential for distal lung formation. Furthermore, RA upregulates P450RAI expression, suggesting the presence of feedback mechanisms controlling RA availability. Our study illustrates the importance of regional mechanisms that control RA availability and utilization for correct expression of pattern regulators and normal morphogenesis during lung development.