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Diabetologia Mar 2020The circadian system generates endogenous rhythms of approximately 24 h, the synchronisation of which are vital for healthy bodily function. The timing of many... (Review)
Review
The circadian system generates endogenous rhythms of approximately 24 h, the synchronisation of which are vital for healthy bodily function. The timing of many physiological processes, including glucose metabolism, are coordinated by the circadian system, and circadian disruptions that desynchronise or misalign these rhythms can result in adverse health outcomes. In this review, we cover the role of the circadian system and its disruption in glucose metabolism in healthy individuals and individuals with type 2 diabetes mellitus. We begin by defining circadian rhythms and circadian disruption and then we provide an overview of circadian regulation of glucose metabolism. We next discuss the impact of circadian disruptions on glucose control and type 2 diabetes. Given the concurrent high prevalence of type 2 diabetes and circadian disruption, understanding the mechanisms underlying the impact of circadian disruption on glucose metabolism may aid in improving glycaemic control.
Topics: Animals; Blood Glucose; Carbohydrate Metabolism; Chronobiology Disorders; Circadian Rhythm; Diabetes Mellitus, Type 2; Glucose; Humans; Insulin-Secreting Cells; Risk Factors; Sleep
PubMed: 31915891
DOI: 10.1007/s00125-019-05059-6 -
Brain, Behavior, and Immunity Jul 2015Cortisol and inflammatory proteins are released into the blood in response to stressors and chronic elevations of blood cortisol and inflammatory proteins may contribute...
Cortisol and inflammatory proteins are released into the blood in response to stressors and chronic elevations of blood cortisol and inflammatory proteins may contribute to ongoing disease processes and could be useful biomarkers of disease. How chronic circadian misalignment influences cortisol and inflammatory proteins, however, is largely unknown and this was the focus of the current study. Specifically, we examined the influence of weeks of chronic circadian misalignment on cortisol, stress ratings, and pro- and anti-inflammatory proteins in humans. We also compared the effects of acute total sleep deprivation and chronic circadian misalignment on cortisol levels. Healthy, drug free females and males (N=17) aged 20-41 participated. After 3weeks of maintaining consistent sleep-wake schedules at home, six laboratory baseline days and nights, a 40-h constant routine (CR, total sleep deprivation) to examine circadian rhythms for melatonin and cortisol, participants were scheduled to a 25-day laboratory entrainment protocol that resulted in sleep and circadian disruption for eight of the participants. A second constant routine was conducted to reassess melatonin and cortisol rhythms on days 34-35. Plasma cortisol levels were also measured during sampling windows every week and trapezoidal area under the curve (AUC) was used to estimate 24-h cortisol levels. Inflammatory proteins were assessed at baseline and near the end of the entrainment protocol. Acute total sleep deprivation significantly increased cortisol levels (p<0.0001), whereas chronic circadian misalignment significantly reduced cortisol levels (p<0.05). Participants who exhibited normal circadian phase relationships with the wakefulness-sleep schedule showed little change in cortisol levels. Stress ratings increased during acute sleep deprivation (p<0.0001), whereas stress ratings remained low across weeks of study for both the misaligned and synchronized control group. Circadian misalignment significantly increased plasma tumor necrosis factor-alpha (TNF-α), interleukin 10 (IL-10) and C-reactive protein (CRP) (p<0.05). Little change was observed for the TNF-α/IL-10 ratio during circadian misalignment, whereas the TNF-α/IL-10 ratio and CRP levels decreased in the synchronized control group across weeks of circadian entrainment. The current findings demonstrate that total sleep deprivation and chronic circadian misalignment modulate cortisol levels and that chronic circadian misalignment increases plasma concentrations of pro- and anti-inflammatory proteins.
Topics: Adult; Biomarkers; C-Reactive Protein; Circadian Rhythm; Female; Humans; Hydrocortisone; Interleukin-10; Male; Melatonin; Sleep Deprivation; Stress, Physiological; Tumor Necrosis Factor-alpha; Young Adult
PubMed: 25640603
DOI: 10.1016/j.bbi.2015.01.004 -
Scoliosis and Spinal Disorders 2018The physiological sagittal spinal curvature represents a typical feature of good body posture in the sagittal plane. The cervical and the lumbar spine are curved... (Review)
Review
BACKGROUND
The physiological sagittal spinal curvature represents a typical feature of good body posture in the sagittal plane. The cervical and the lumbar spine are curved anteriorly (lordosis), while the thoracic segment is curved posteriorly (kyphosis). The pelvis is inclined anteriorly, and the lower limbs' joints remain in a neutral position. However, there are many deviations from the optimal body alignment.The aim of this paper is to present the most common types of non-structural misalignments of the body posture in the sagittal plane.
MAIN BODY OF THE ABSTRACT
The most common types of non-structural misalignments of body posture in the sagittal plane are as follows: (1) lordotic, (2) kyphotic, (3) flat-back, and (4) sway-back postures. Each one may influence both the skeletal and the muscular system leading to the functional disturbance and an increased strain of the supporting structures. Usually, the disturbances localized within the muscles are analyzed in respect to their shortening or lengthening. However, according to suggestions presented in the literature, when the muscles responsible for maintaining good body posture (the so-called stabilizers) are not being stimulated to resist against gravity for an extended period of time, e.g., during prolonged sitting, their stabilizing function is disturbed by the hypoactivity reaction resulting in muscular weakness. The deficit of the locomotor system stability triggers a compensatory mechanism-the stabilizing function is overtaken by the so-called mobilizing muscles. However, as a side effect, such compensation leads to the increased activity of mobilizers (hyperactivity) and decreased flexibility, which may finally lead to the pathological chain of reaction within the musculoskeletal system.
CONCLUSIONS
There exist four principal types of non-structural body posture misalignments in the sagittal plane: lordotic posture, kyphotic posture, flat-back posture, and sway-back posture. Each of them can disturb the physiological loading of the musculoskeletal system in a specific way, which may lead to a functional disorder.When planning postural corrective exercises, not only the analysis of muscles in respect to their shortening and lengthening but also their hypoactivity and hyperactivity should be considered.
PubMed: 29516039
DOI: 10.1186/s13013-018-0151-5 -
Proceedings of the National Academy of... Mar 2016Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the... (Randomized Controlled Trial)
Randomized Controlled Trial
Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the key features of shift workers is that their behavioral and environmental cycles are typically misaligned relative to their endogenous circadian system. However, there is little information on the impact of acute circadian misalignment on cardiovascular disease risk in humans. Here we show-by using two 8-d laboratory protocols-that short-term circadian misalignment (12-h inverted behavioral and environmental cycles for three days) adversely affects cardiovascular risk factors in healthy adults. Circadian misalignment increased 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3.0 mmHg and 1.5 mmHg, respectively. These results were primarily explained by an increase in blood pressure during sleep opportunities (SBP, +5.6 mmHg; DBP, +1.9 mmHg) and, to a lesser extent, by raised blood pressure during wake periods (SBP, +1.6 mmHg; DBP, +1.4 mmHg). Circadian misalignment decreased wake cardiac vagal modulation by 8-15%, as determined by heart rate variability analysis, and decreased 24-h urinary epinephrine excretion rate by 7%, without a significant effect on 24-h urinary norepinephrine excretion rate. Circadian misalignment increased 24-h serum interleukin-6, C-reactive protein, resistin, and tumor necrosis factor-α levels by 3-29%. We demonstrate that circadian misalignment per se increases blood pressure and inflammatory markers. Our findings may help explain why shift work increases hypertension, inflammation, and cardiovascular disease risk.
Topics: Actigraphy; Adult; Blood Pressure; C-Reactive Protein; Cardiovascular Diseases; Circadian Rhythm; Cross-Over Studies; Epinephrine; Female; Heart Rate; Humans; Hypertension; Interleukin-6; Male; Middle Aged; Polysomnography; Resistin; Risk Factors; Sleep Disorders, Circadian Rhythm; Time Factors; Tumor Necrosis Factor-alpha; Work Schedule Tolerance; Young Adult
PubMed: 26858430
DOI: 10.1073/pnas.1516953113 -
International Review of Psychiatry... Apr 2014Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep... (Review)
Review
Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep propensity. The term 'circadian misalignment' describes a variety of circumstances, such as inappropriately timed sleep and wake, misalignment of sleep/wake with feeding rhythms, or misaligned central and peripheral rhythms. The predominance of early research focused on misalignment of sleep to the biological night. However, discovery of clock genes and the presence of peripheral circadian oscillators have expanded the definitions of misalignment. Experimental studies conducted in animal models and humans have provided evidence of potential mechanisms that link misalignment to negative outcomes. These include dysregulation of feeding behaviours, changes in appetite stimulating hormones, glucose metabolism and mood. This review has two foci: (1) to describe how circadian misalignment has been defined and evaluated in laboratory and field experiments, and (2) to describe evidence linking different types of circadian misalignment to increased risk for physical (cardiovascular disease, diabetes, obesity, cancer) and psychiatric (depression, bipolar, schizophrenia, attention deficit) disorders. This review will describe the role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders.
Topics: Animals; Chronobiology Disorders; Circadian Rhythm; Humans; Mental Disorders; Risk Factors; Sleep Wake Disorders
PubMed: 24892891
DOI: 10.3109/09540261.2014.911149 -
Cold Spring Harbor Perspectives in... Apr 2013The mismatch repair (MMR) system detects non-Watson-Crick base pairs and strand misalignments arising during DNA replication and mediates their removal by catalyzing... (Review)
Review
The mismatch repair (MMR) system detects non-Watson-Crick base pairs and strand misalignments arising during DNA replication and mediates their removal by catalyzing excision of the mispair-containing tract of nascent DNA and its error-free resynthesis. In this way, MMR improves the fidelity of replication by several orders of magnitude. It also addresses mispairs and strand misalignments arising during recombination and prevents synapses between nonidentical DNA sequences. Unsurprisingly, MMR malfunction brings about genomic instability that leads to cancer in mammals. But MMR proteins have recently been implicated also in other processes of DNA metabolism, such as DNA damage signaling, antibody diversification, and repair of interstrand cross-links and oxidative DNA damage, in which their functions remain to be elucidated. This article reviews the progress in our understanding of the mechanism of replication error repair made during the past decade.
Topics: Amino Acid Sequence; Animals; Base Pair Mismatch; DNA; DNA Damage; DNA Mismatch Repair; DNA Repair; Escherichia coli; Escherichia coli Proteins; Humans; Molecular Sequence Data; MutS DNA Mismatch-Binding Protein; Protein Conformation; Recombination, Genetic; Reproducibility of Results; Sequence Homology, Amino Acid; Signal Transduction
PubMed: 23545421
DOI: 10.1101/cshperspect.a012633 -
Journal of Neuroendocrinology Jun 2022Rhythmic hormonal secretion is key for sustaining health. While a central pacemaker in the hypothalamus is the main driver of circadian periodicity, many hormones... (Review)
Review
Rhythmic hormonal secretion is key for sustaining health. While a central pacemaker in the hypothalamus is the main driver of circadian periodicity, many hormones oscillate with different frequencies and amplitudes. These rhythms carry information about healthy physiological functions, while at the same time they must be able to respond to external cues and maintain their robustness against severe perturbations. Since endocrine disruptions can lead to hormonal misalignment and disease, understanding the clinical significance of these rhythms can help support diagnosis and disease management. While the misalignment of dynamic hormone profiles can be quantitatively analysed though statistical and computational techniques, mathematical modelling can provide fundamental understanding about the mechanisms underpinning endocrine rhythms, particularly around the question of what makes them robust to some perturbations but fragile to others. In this study, I will review the key challenges of understanding hormonal rhythm misalignment from a mathematical perspective, including their causes and clinical significance. By reviewing modelling examples of coupled endocrine axes, I will address the question of how perturbations in one endocrine axis propagate to another, leading to the more complex issue of disentangling the contribution of each endocrine system to a robust dynamic environment.
Topics: Circadian Rhythm; Endocrine System; Hormones; Hypothalamus
PubMed: 35514212
DOI: 10.1111/jne.13144 -
JACC. Cardiovascular Interventions May 2020
Topics: Aortic Valve; Aortic Valve Stenosis; Coronary Vessels; Humans; Transcatheter Aortic Valve Replacement; Treatment Outcome
PubMed: 32381183
DOI: 10.1016/j.jcin.2020.03.001 -
Neuroscience and Biobehavioral Reviews Jun 2021Adapting to the changing environment is a key component of optimal decision-making. Internal-models that accurately represent and selectively update from behaviorally... (Review)
Review
Adapting to the changing environment is a key component of optimal decision-making. Internal-models that accurately represent and selectively update from behaviorally relevant/salient stimuli may facilitate adaptive behaviors. Anterior cingulate cortex (ACC) and dopaminergic systems may produce these adaptive internal-models through selective updates from behaviorally relevant stimuli. Dysfunction of ACC and dopaminergic systems could therefore produce misaligned internal-models where updates are disproportionate to the salience of the cues. An aspect of addictive-like behaviors is reduced adaptation and, ACC and dopaminergic systems typically exhibit dysfunction in drug-dependents. We argue that ACC and dopaminergic dysfunction in dependents may produce misaligned internal-models such that drug-related stimuli are misattributed with a higher salience compared to non-drug related stimuli. Hence, drug-related rewarding stimuli generate over-weighted updates to the internal-model, while negative feedback and non-drug related rewarding stimuli generate down-weighted updates. This misaligned internal-model may therefore incorrectly reinforce maladaptive drug-related behaviors. We use the proposed framework to discuss ways behavior may be made more adaptive and how the framework may be supported or falsified experimentally.
Topics: Adaptation, Physiological; Behavior, Addictive; Dopamine; Gyrus Cinguli; Humans; Reward
PubMed: 33657434
DOI: 10.1016/j.neubiorev.2021.02.039 -
Frontiers in Psychology 2023As pioneers of the Carnegie Perspective recognized, conflicts in organizations can exist even when incentives of all parties are aligned. These can often be traced to...
As pioneers of the Carnegie Perspective recognized, conflicts in organizations can exist even when incentives of all parties are aligned. These can often be traced to differences in cognitions such as beliefs and values, which are foundational components of any given culture. This paper refines the operationalization of cultural clashes by identifying differences in beliefs about causality ("which actions cause which outcomes") and morality (in the broad sense of "what is evaluated as desirable") as two fundamental sources of conflict. In our first study, we demonstrate empirically that participants recognize and distinguish between these two sources of conflict. In our second study, we test the hypotheses that while misalignments in either causal or moral codes increase observers' perceptions of relationship conflict, negative affect, likelihood of avoidance, and lower perceived likelihood of conflict resolution, the effects are stronger for misalignments in moral codes than misalignments in causal codes and strongest when both causal and moral codes are misaligned. We test these arguments using vignette-based experimental studies. Our findings support our hypotheses. This research has significant implications for the understanding of conflict dynamics within and beyond organizational contexts. By recognizing the pivotal role of cultural differences in shaping conflicts, organizations and decision-makers can better anticipate, manage, and potentially preempt such conflicts.
PubMed: 37780139
DOI: 10.3389/fpsyg.2023.1166023