Small-molecule CEM3 strengthens single-cell oscillators in the suprachiasmatic nucleus

A robust endogenous clock is required for proper function of many physiological processes. The suprachiasmatic nucleus (SCN) constitutes our central circadian clock and allows us to adapt to daily changes in the environment. Aging can cause a decline in the amplitude of circadian rhythms in SCN and peripheral clocks, which contributes to increased risk of several chronic diseases. Strengthening clock function would therefore be an effective strategy to improve health. A high-throughput chemical screening has identified clock-enhancing molecule 3 (CEM3) as small molecule that increases circadian rhythm amplitude in cell lines and SCN explants. It is, however, currently not known whether CEM3 acts by enhancing the amplitude of individual single-cell oscillators or by enhancing synchrony among neurons. In view of CEM3's potential, it is of evident importance to clarify the mode of action of CEM3. Here, we investigated the effects of CEM3 on single-cell PERIOD2::LUCIFERASE rhythms in mouse SCN explants. CEM3 increased the amplitude in approximately 80%-90% of the individual cells in the SCN without disrupting the phase and/or period of their rhythms. Noticeably, CEM3's effect on amplitude is independent of the cell's initial amplitude. These findings make CEM3 a potential therapeutic candidate to restore compromised amplitude in circadian rhythms and will boost the development of other molecular approaches to improve health.

Internal circadian misallignment in a mouse model of chemotherapy induced fatigue

BACKGROUND

Cancer survivors can experience long lasting fatigue resulting in a lower quality of life. How chemotherapy treatment contributes to this fatigue is poorly understood. Previously we have shown in a mouse model of cancer related fatigue that doxorubicin treatment induces fatigue-like symptoms related to disturbed circadian rhythms. However, the specific components of the circadian regulatory circuitry affected by doxorubicin treatment remained unclear. Therefore we investigated the role of the central circadian clock, the suprachiasmatic nucleus (SCN), in chemotherapy-induced fatigue.

METHODS

We measured circadian controlled behavior and multiunit neuronal activity in the SCN in freely moving mice exhibiting fatigue-like behavior after doxorubicin treatment under both light-dark (LD) and constant dark (DD) conditions. Additionally, we assessed the expression of inflammation related genes in spleen and kidney as potential inducers of CRF.

RESULTS

Doxorubicin treatment significantly reduced both the running wheel activity and time spent using the running wheel for over five weeks after treatment. In contrast to the pronounced effects on behavior and neuronal activity of doxorubicin on circadian rhythms, peripheral inflammation markers only showed minor differences, five weeks after the last treatment. Surprisingly, the circadian SCN neuronal activity under both LD and DD conditions was not affected. However, the circadian timing of neuronal activity in peri-SCN areas (the brain areas surrounding SCN) and circadian rest-activity behavior was strongly affected by doxorubicin, suggesting that the output of the SCN was altered. The reduced correlation between the SCN neuronal activity and behavioral activity after doxorubicin treatment, suggests that the information flow from the SCN to the periphery was disturbed.

CONCLUSION

Our preclinical study suggests that chemotherapy-induced fatigue disrupts the circadian rhythms in peripheral brain areas and behavior downstream from the SCN, potentially leading to fatigue like symptoms. Our data suggest that peripheral inflammation responses are less important for the maintenance of fatigue. Chronotherapy that realigns circadian rhythms could represent a non-invasive way to improve patient outcomes following chemotherapy.

One seasonal clock fits all?

Adaptation of physiology and behavior to seasonal changes in the environment are for many organisms essential for survival. Most of our knowledge about the underlying mechanisms comes from research on photoperiodic regulation of reproduction in plants, insects and mammals. However, even humans, who mostly live in environments with minimal seasonal influences, show annual rhythms in physiology (e.g., immune activity, brain function), behavior (e.g., sleep-wake cycles) and disease prevalence (e.g., infectious diseases). As seasonal variations in environmental conditions may be drastically altered due to climate change, the understanding of the mechanisms underlying seasonal adaptation of physiology and behavior becomes even more relevant. While many species have developed specific solutions for dedicated tasks of photoperiodic regulation, we find a number of common principles and mechanisms when comparing insect and mammalian systems: (1) the circadian system contributes to photoperiodic regulation; (2) similar signaling molecules (VIP and PDF) are used for transferring information from the circadian system to the neuroendocrine system controlling the photoperiodic response; (3) the hormone melatonin participates in seasonal adaptation in insects as well as mammals; and (4) changes in photoperiod affect neurotransmitter function in both animal groups. The few examples of overlap elaborated in this perspective article, as well as the discussion on relevance for humans, should be seen as encouragement to unravel the machinery of seasonal adaptation in a multitude of organisms.

Impact of ERAS in breast reconstruction with a latissimus dorsi flap, compared to conventional management

BACKGROUND

Enhanced recovery after surgery (ERAS) programs are associated with improved management, reduced hospital stays, and lower complication rates.

OBJECTIVE

To evaluate the impact of ERAS on mean length of stay (LOS) and postoperative morbidity in breast reconstruction with latissimus dorsi flap (LDF) compared with conventional recovery program.

PATIENTS AND METHOD

All patients operated by LDF between December 2014 and October 2020: those managed before April 2018, when the ERAS protocol was introduced, were included in the "no ERAS" group, and beyond in the "ERAS" group.

RESULTS

Out of 193 patients, 129 were included in the "ERAS" group and 64 in the "no ERAS" group. There was a significant difference between the two groups in LOS (4.2 ± 1.5 days in the "ERAS" group vs. 5.4 ± 1.9 days in the "no ERAS" group; p < 0.001), high-grade complications at 30 days (9.3% in the "ERAS" group vs. 25% in the "no ERAS" group; p = 0.01), reintervention rate (13.9% vs. 26.6%, respectively; p = 0.02), and 30-day rehospitalization rate (6.2% in the "ERAS" group vs. 15.6% in the "no ERAS" group; p = 0.03).

CONCLUSION

The ERAS protocol has a positive impact on breast reconstruction with LDF without generating additional adverse effects. These results support the democratization of these programs for breast reconstruction surgery.

Reduced Plasticity in Coupling Strength in the Aging SCN Clock as Revealed by Kuramoto Modeling

The mammalian circadian clock is located in the suprachiasmatic nucleus (SCN) and consists of a network of coupled neurons, which are entrained to the environmental light-dark cycle. The phase coherence of the neurons is plastic and driven by the duration of daylight. With aging, the capacity to behaviorally adapt to seasonal changes in photoperiod reduces. The mechanisms underlying photoperiodic adaptation are largely unknown, but are important to unravel for the development of novel interventions to improve the quality of life of the elderly. We analyzed the phase coherence of single-cell PERIOD2::LUCIFERASE (PER2::LUC) expression rhythms in the SCN of young and old mice entrained to either long or short photoperiod. The phase coherence was used as input to a 2-community noisy Kuramoto model to estimate the coupling strength between and within neuronal subpopulations. The model revealed a correlation between coupling strength and photoperiod-induced changes in the phase relationship among neurons, suggesting a functional link. We found that the SCN of young mice adapts in coupling strength over a large range, with weak coupling in long photoperiod (LP) and strong coupling in short photoperiod (SP). In aged mice, we also found weak coupling in LP, but a reduced capacity to reach strong coupling in SP. The inability to respond with an increase in coupling strength suggests that manipulation of photoperiod is not a suitable strategy to enhance clock function with aging. We conclude that the inability of aged mice to reach strong coupling contributes to deficits in behavioral adaptation to seasonal changes in photoperiod.

Vibrational-mechanical properties of the highly-mismatched Cd1-xBexTe semiconductor alloy: experiment and ab initio calculations

The emerging CdTe-BeTe semiconductor alloy that exhibits a dramatic mismatch in bond covalency and bond stiffness clarifying its vibrational-mechanical properties is used as a benchmark to test the limits of the percolation model (PM) worked out to explain the complex Raman spectra of the related but less contrasted Zn1-xBex-chalcogenides. The test is done by way of experiment ([Formula: see text]), combining Raman scattering with X-ray diffraction at high pressure, and ab initio calculations ([Formula: see text] ~ 0-0.5; [Formula: see text]~1). The (macroscopic) bulk modulus [Formula: see text] drops below the CdTe value on minor Be incorporation, at variance with a linear [Formula: see text] versus [Formula: see text] increase predicted ab initio, thus hinting at large anharmonic effects in the real crystal. Yet, no anomaly occurs at the (microscopic) bond scale as the regular bimodal PM-type Raman signal predicted ab initio for Be-Te in minority ([Formula: see text]~0, 0.5) is barely detected experimentally. At large Be content ([Formula: see text]~1), the same bimodal signal relaxes all the way down to inversion, an unprecedented case. However, specific pressure dependencies of the regular ([Formula: see text]~0, 0.5) and inverted ([Formula: see text]~1) Be-Te Raman doublets are in line with the predictions of the PM. Hence, the PM applies as such to Cd1-xBexTe without further refinement, albeit in a "relaxed" form. This enhances the model's validity as a generic descriptor of phonons in alloys.

[Adverse effects of licorice consumed as food: An update]

The word "licorice" refers to the plant, its root, and its aromatic extract. From a commercial point of view, Glycyrrhiza glabra is the most important species with a wide range of uses (herbal medicine, tobacco industry, cosmetics, food and pharmaceutical). Glycyrrhizin is one of the main constituents of licorice. Glycyrrhizin is hydrolyzed in the intestinal lumen by bacterial β-glucuronidases to 3β-monoglucuronyl-18β-glycyrrhetinic acid (3MGA) and 18β-glycyrrhetinic acid (GA), which are metabolized in the liver. Plasma clearance is slow due to enterohepatic cycling. 3MGA and GA can bind to mineralocorticoid receptors with very low affinity, and 3MGA induces apparent mineralocorticoid excess syndrome through dose-dependent inhibition of 11β-hydroxysteroid dehydrogenase type 2 in renal tissue. The cases of apparent mineralocorticoid excess syndrome reported in the literature are numerous and sometimes severe, even fatal, most often in cases of chronic high dose consumption. Glycyrrhizin poisonings are characterized by hypertension, fluid retention, and hypokalemia with metabolic alkalosis and increased kaliuresis. Toxicity depends on the dose, the type of product consumed, the mode of consumption (acute or chronic) and a very large inter-individual variability. The diagnosis of glycyrrhizin-induced apparent mineralocorticoid excess syndrome is based on the history, clinical examination, and biochemical analysis. Management is primarily based on symptomatic care and stopping licorice consumption.

Aging affects GABAergic function and calcium homeostasis in the mammalian central clock

Introduction

Aging impairs the function of the central circadian clock in mammals, the suprachiasmatic nucleus (SCN), leading to a reduction in the output signal. The weaker timing signal from the SCN results in a decline in rhythm strength in many physiological functions, including sleep-wake patterns. Accumulating evidence suggests that the reduced amplitude of the SCN signal is caused by a decreased synchrony among the SCN neurons. The present study was aimed to investigate the hypothesis that the excitation/inhibition (E/I) balance plays a role in synchronization within the network.

Methods

Using calcium (Ca²⁺) imaging, the polarity of Ca²⁺ transients in response to GABA stimulation in SCN slices of old mice (20-24 months) and young controls was studied.

Results

We found that the amount of GABAergic excitation was increased, and that concordantly the E/I balance was higher in SCN slices of old mice when compared to young controls. Moreover, we showed an effect of aging on the baseline intracellular Ca²⁺ concentration, with higher Ca²⁺ levels in SCN neurons of old mice, indicating an alteration in Ca²⁺ homeostasis in the aged SCN. We conclude that the change in GABAergic function, and possibly the Ca²⁺ homeostasis, in SCN neurons may contribute to the altered synchrony within the aged SCN network.

Alternative scoring methods of fusarium head blight resistance for genomic assisted breeding

Fusarium head blight (FHB) is a fungal disease of wheat (Triticum aestivum.L) that causes yield losses and produces mycotoxins which could easily exceed the limits of the EU regulations. Resistance to FHB has a complex genetic architecture and accurate evaluation in breeding programs is key to selecting resistant varieties. The Area Under the Disease Progress Curve (AUDPC) is one of the commonly metric used as a standard methodology to score FHB. Although efficient, AUDPC requires significant costs in phenotyping to cover the entire disease development pattern. Here, we show that there are more efficient alternatives to AUDPC (angle, growing degree days to reach 50% FHB severity, and FHB maximum variance) that reduce the number of field assessments required and allow for fair comparisons between unbalanced evaluations across trials. Furthermore, we found that the evaluation method that captures the maximum variance in FHB severity across plots is the most optimal approach for scoring FHB. In addition, results obtained on experimental data were validated on a simulated experiment where the disease progress curve was modeled as a sigmoid curve with known parameters and assessment protocols were fully controlled. Results show that alternative metrics tested in this study captured key components of quantitative plant resistance. Moreover, the new metrics could be a starting point for more accurate methods for measuring FHB in the field. For example, the optimal interval for FHB evaluation could be predicted using prior knowledge from historical weather data and FHB scores from previous trials. Finally, the evaluation methods presented in this study can reduce the FHB phenotyping burden in plant breeding with minimal losses on signal detection, resulting in a response variable available to use in data-driven analysis such as genome-wide association studies or genomic selection.

Single cell model for re-entrainment to a shifted light cycle

Our daily 24-h rhythm is synchronized to the external light-dark cycle resulting from the Earth's daily rotation. In the mammalian brain, the suprachiasmatic nucleus (SCN) serves as the master clock and receives light-mediated input via the retinohypothalamic tract. Abrupt changes in the timing of the light-dark cycle (e.g., due to jet lag) cause a phase shift in the circadian rhythms in the SCN. Here, we investigated the effects of a 6-h delay in the light-dark cycle on PERIOD2::LUCIFERASE expression at the single-cell level in mouse SCN organotypic explants. The ensemble pattern in phase shift response obtained from individual neurons in the anterior and central SCN revealed a bimodal distribution; specifically, neurons in the ventrolateral SCN responded with a rapid phase shift, while neurons in the dorsal SCN generally did not respond to the shift in the light-dark cycle. We also stimulated the hypothalamic tract in acute SCN slices to simulate light-mediated input to the SCN; interestingly, we found similarities between the distribution and fraction of rapid shifting neurons (in response to the delay) and neurons that were excited in response to electrical stimulation. These results suggest that a subpopulation of neurons in the ventral SCN that have an excitatory response to light input, shift their clock more readily than dorsal located neurons, and initiate the SCN's entrainment to the new light-dark cycle. Thus, we propose that light-excited neurons in the anterior and central SCN play an important role in the organism's ability to adjust to changes in the external light-dark cycle.

Induction of Fatigue by Specific Anthracycline Cancer Drugs through Disruption of the Circadian Pacemaker

Simple Summary

Cancer-related fatigue (CRF) is a devastating side effect of cancer treatment, affecting the quality of life of many patients for years after treatment. This long-term side effect often results in loss of social functioning and even job loss. The cause of CRF is unknown, and consequently, CRF is often considered a ‘psychological problem’, much to the frustration of the patients. Here, we show in an animal model that the severity of CRF depends on the working mechanism of the treatment. In addition, the data show that the CRF is probably caused by a dysfunctioning circadian clock and thus has a physiological basis, as this effect depends on the anticancer drug. Therefore, the findings may have implications for the selection of chemotherapy and thus strongly improve the quality of life of future cancer survivors.

Abstract

Cancer-related fatigue (CRF) is the most devastating long-term side effect of many cancer survivors that confounds the quality of life for months to years after treatment. However, the cause of CRF is poorly understood. As a result, cancer survivors, at best, receive psychological support. Chemotherapy has been shown to increase the risk of CRF. Here, we study therapy-induced fatigue in a non-tumor-bearing mouse model with three different topoisomerase II-poisoning cancer drugs. These drugs either induce DNA damage and/or chromatin damage. Shortly before and several weeks after treatment, running wheel activity and electroencephalographic sleep were recorded. We show that doxorubicin, combining DNA damage with chromatin damage, unlike aclarubicin or etoposide, induces sustained CRF in this model. Surprisingly, this was not related to changes in sleep. In contrast, our data indicate that the therapy-induced CRF is associated with a disrupted circadian clock. The data suggest that CRF is probably a circadian clock disorder that influences the quality of waking and that the development of CRF depends on the type of chemotherapy provided. These findings could have implications for selecting and improving chemotherapy for the treatment of cancer in order to prevent the development of CRF.

The aging brain: sleep, the circadian clock and exercise

Aging is a multifactorial process likely stemming from damage accumulation and/or a decline in maintenance and repair mechanisms in the organisms that eventually determine their lifespan. In our review, we focus on the morphological and functional alterations that the aging brain undergoes affecting sleep and the circadian clock in both human and rodent models. Although both species share mammalian features, differences have been identified on several experimental levels, which we outline in this review. Additionally, we delineate some challenges on the preferred analysis and we suggest that a uniform route is followed so that findings can be smoothly compared. We conclude by discussing potential interventions and highlight the influence of physical exercise as a beneficial lifestyle intervention, and its effect on healthy aging and longevity. We emphasize that even moderate age-matched exercise is able to ameliorate several aging characteristics as far as sleep and circadian rhythms are concerned, independent of the species studied.

A multi-level assessment of the bidirectional relationship between aging and the circadian clock

The daily temporal order of physiological processes and behavior contribute to the wellbeing of many organisms including humans. The central circadian clock, which coordinates the timing within our body, is located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Like in other parts of the brain, aging impairs the SCN function, which in turn promotes the development and progression of aging-related diseases. We here review the impact of aging on the different levels of the circadian clock machinery-from molecules to organs-with a focus on the role of the SCN. We find that the molecular clock is less effected by aging compared to other cellular components of the clock. Proper rhythmic regulation of intracellular signaling, ion channels and neuronal excitability of SCN neurons are greatly disturbed in aging. This suggests a disconnection between the molecular clock and the electrophysiology of these cells. The neuronal network of the SCN is able to compensate for some of these cellular deficits. However, it still results in a clear reduction in the amplitude of the SCN electrical rhythm, suggesting a weakening of the output timing signal. Consequently, other brain areas and organs not only show aging-related deficits in their own local clocks, but also receive a weaker systemic timing signal. The negative spiral completes with the weakening of positive feedback from the periphery to the SCN. Consequently, chronotherapeutic interventions should aim at strengthening overall synchrony in the circadian system using life-style and/or pharmacological approaches.

Electrophysiological Approaches to Studying the Suprachiasmatic Nucleus

In mammals, the part of the nervous system responsible for most circadian behavior can be localized to a bilaterally paired structure in the hypothalamus known as the suprachiasmatic nucleus (SCN). Understanding the mammalian circadian system will require a detailed multilevel analysis of neural SCN circuits ex vivo and in vivo. Many of the techniques and approaches that are used for the analysis of the circuitry driving circadian oscillations in the SCN are similar to those employed in other brain regions. There is, however, one fundamental difference that needs to be taken into consideration, that is, the physiological, cell, and molecular properties of SCN neurons vary with the time of day. In this chapter, we will consider the preparations and electrophysiological techniques that we have used to analyze the SCN circuit focusing on the acute brain slice and intact, freely moving animal.

Evaluation of the combination of endothelin receptor antagonists (ERA) and phosphodiesterase-5 inhibitors for the treatment of pulmonary arterial hypertension (PAH) in pathologic human pulmonary arteries in an ex-vivo organ bath model

PURPOSE

Medical combination therapy of pulmonary arterial hypertension (PAH) may alleviate the drawbacks of monotherapy by avoiding drug tolerance and by increasing effectiveness, as shown by the combination of ambrisentan and tadalafil (AMBITION trial). The present ex-vivo study evaluated the combination of the endothelin receptor antagonists (ERA) macitentan and bosentan with the phosphodiesterase-5 (PDE-5) inhibitor vardenafil in pulmonary arteries from patients suffering from terminal lung disease as a model of PAH.

METHODS

Segments of the pulmonary vessels were excised from resected lungs of patients requiring lung transplantation (LTX). Contraction of pulmonary arteries (PA) was elicited by consecutive dose-response curves of endothelin-1 (ET-1) followed by norepinephrine (NE) to allow inhibition by different pathways. Forces were measured isometrically in an organ bath in the presence and absence of ERA and PDE-5 inhibitors and their combination.

RESULTS

PA of 38 patients were examined between October 2016 and November 2019. Bosentan (1E-7 M) and macitentan (1E-8 M, 3E-8 M, 1E-7 M) inhibited ET-1 induced contractions, whereas vardenafil (1E-6 M, 3E-6 M, 1E-5 M) inhibited only the NE induced part of the contractions. Vardenafil enhanced bosentan-induced inhibition of vasoconstriction in a dose-dependent fashion. Combination effects exceeded single bosentan at 3E-6 M and 1E-5 M vardenafil, and they exceeded single vardenafil at the lower vardenafil concentrations. Macitentan showed a more pronounced inhibition than bosentan regardless of the lower concentrations. Accordingly, combination effects with vardenafil resembled those of macitentan alone.

CONCLUSIONS

Macitentan and bosentan were potent antagonists of vasoconstriction in PA of LTX patients. The benefit of drug combinations was demonstrated at selected concentrations only owing to a narrow therapeutic range of vardenafil in this ex-vivo model. These results suggest the utility of drug combinations other than the established pair of ambrisentan and tadalafil in PAH treatment but also make a case for a further assessment of vasodilator properties of drugs complementing ERA.

Long-term effects of an intensive prevention program (IPP) after acute myocardial infarction – the IPP Follow-up and Prevention Boost Trial

Background

The effects of an intensive prevention program (IPP) for 12 months following 3-week rehabilitation after myocardial infarction (MI) have been proven by the randomized IPP trial. The present study investigates if the effects of IPP persist one year after termination of the program and if a reintervention after &gt;24 months (“prevention boost”) is effective.

Methods

In the IPP trial patients were recruited during hospitalization for acute MI and randomly assigned to IPP versus usual care (UC) one month after discharge (after 3-week rehabilitation). IPP was coordinated by non-physician prevention assistants and included intensive group education sessions, telephone calls, telemetric and clinical control of risk factors. Primary study endpoint was the IPP Prevention Score, a sum score evaluating six major risk factors. The score ranges from 0 to 15 points, with a score of 15 points indicating best risk factor control.

In the present study the effects of IPP were investigated after 24 months – one year after termination of the program. Thereafter, patients of the IPP study arm with at least one insufficiently controlled risk factor were randomly assigned to a 2-months reintervention (“prevention boost”) vs. no reintervention.

Results

At long-term follow-up after 24 months, 129 patients of the IPP study arm were compared to 136 patients of the UC study arm. IPP was associated with a significantly better risk factor control compared to UC at 24 months (IPP Prevention Score 10.9±2.3 points in the IPP group vs. 9.4±2.3 points in the UC group, p&lt;0.01). However, in the IPP group a decrease of risk factor control was observed at the 24-months visit compared to the 12-months visit at the end of the prevention program (IPP Prevention Score 10.9±2.3 points at 24 months vs. 11.6±2.2 points at 12 months, p&lt;0.05, Figure 1).

A 2-months reintervention (“prevention boost”) was effective to improve risk factor control during long-term course: IPP Prevention Score increased from 10.5±2.1 points to 10.7±1.9 points in the reintervention group, while it decreased from 10.5±2.1 points to 9.7±2.1 points in the group without reintervention (p&lt;0.05 between the groups, Figure 1).

Conclusions

IPP was associated with a better risk factor control compared to UC during 24 months; however, a deterioration of risk factors after termination of IPP suggests that even a 12-months prevention program is not long enough. The effects of a short reintervention after &gt;24 months (“prevention boost”) indicate the need for prevention concepts that are based on repetitive personal contacts during long-term course after coronary events.

Figure 1

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Stiftung Bremer Herzen (Bremen Heart Foundation)

Brief light exposure at dawn and dusk can encode day-length in the neuronal network of the mammalian circadian pacemaker

The central circadian pacemaker in mammals, the suprachiasmatic nucleus (SCN), is important for daily as well as seasonal rhythms. The SCN encodes seasonal changes in day length by adjusting phase distribution among oscillating neurons thereby shaping the output signal used for adaptation of physiology and behavior. It is well-established that brief light exposure at the beginning and end of the day, also referred to as "skeleton" light pulses, are sufficient to evoke the seasonal behavioral phenotype. However, the effect of skeleton light exposure on SCN network reorganization remains unknown. Therefore, we exposed mice to brief morning and evening light pulses that mark the time of dawn and dusk in a short winter- or a long summer day. Single-cell PER2::LUC recordings, electrophysiological recordings of SCN activity, and measurements of GABA response polarity revealed that skeleton light-regimes affected the SCN network to the same degree as full photoperiod. These results indicate the powerful, yet potentially harmful effects of even relatively short light exposures during the evening or night for nocturnal animals.

The predictable chaos of slow earthquakes

Slow earthquakes, like regular earthquakes, result from unstable frictional slip. They produce little slip and can therefore repeat frequently. We assess their predictability using the slip history of the Cascadia subduction between 2007 and 2017, during which slow earthquakes have repeatedly ruptured multiple segments. We characterize the system dynamics using embedding theory and extreme value theory. The analysis reveals a low-dimensional (<5) nonlinear chaotic system rather than a stochastic system. We calculate properties of the underlying attractor like its correlation and instantaneous dimension, instantaneous persistence, and metric entropy. We infer that the system has a predictability horizon of the order of days weeks. For the better resolved segments, the onset of large slip events can be correctly forecasted by high values of the instantaneous dimension. Longer-term deterministic prediction seems intrinsically impossible. Regular earthquakes might similarly be predictable but with a limited predictable horizon of the order of their durations.

Females with cystic fibrosis have a larger decrease in sweat chloride in response to lumacaftor/ivacaftor compared to males

AIM

To explore which patient-related factors influence sweat test response to CFTR modulators, as well as examining the correlation between the sweat chloride response and ppFEV₁ or BMI response, using systematically collected real-life clinical data.

METHODS

160 CF patients were identified who had used lumacaftor/ivacaftor for at least six months. Of these patients, age, sweat chloride levels, ppFEV₁ weight and BMI at the start of treatment and after 6 months were collected retrospectively. Pearson and Spearman tests were performed to assess correlations.

RESULTS

Females compared to males in this group showed a larger response in sweat chloride (mean difference 10.6 mmol/l, 95% CI: 5.7-15.4) and BMI (mean difference 0.27 kg/m², 95% CI: 0.01-0.54). A modest but significant correlation was found between patient weight and sweat chloride response (Pearson R = 0.244, p = 0.001), which diminished upon correction for the other factors. The correlation between sex and sweat chloride response remained; R = 0.253, p = 0.001. Sweat chloride response did not correlate with ppFEV₁ change or BMI change at 6 months after start of therapy.

CONCLUSION

Sweat chloride response is larger in females compared to males, which also explains the negative correlation of weight with the response in sweat chloride concentration after start of lumacaftor/ivacaftor. Sweat chloride response does not correlate with the responses in ppFEV₁ and BMI. This information may help the interpretation of sweat test results acquired for the follow up and evaluation of CFTR modulating treatments, and warrants further investigation into the underlying mechanisms of sex differences in response to CFTR modulators.

Aging Affects the Capacity of Photoperiodic Adaptation Downstream from the Central Molecular Clock

Aging impairs circadian clock function, leading to disrupted sleep-wake patterns and a reduced capability to adapt to changes in environmental light conditions. This makes shift work or the changing of time zones challenging for the elderly and, importantly, is associated with the development of age-related diseases. However, it is unclear what levels of the clock machinery are affected by aging, which is relevant for the development of targeted interventions. We found that naturally aged mice of >24 months had a reduced rhythm amplitude in behavior compared with young controls (3-6 months). Moreover, the old animals had a strongly reduced ability to adapt to short photoperiods. Recording PER2::LUC protein expression in the suprachiasmatic nucleus revealed no impairment of the rhythms in PER2 protein under the 3 different photoperiods tested (LD: 8:16, 12:12, and 16:8). Thus, we observed a discrepancy between the behavioral phenotype and the molecular clock, and we conclude that the aging-related deficits emerge downstream of the core molecular clock. Since it is known that aging affects several intracellular and membrane components of the central clock cells, it is likely that an impairment of the interaction between the molecular clock and these components is contributing to the deficits in photoperiod adaptation.

P6214How to improve long-term prevention in young patients after myocardial infarction - the IPP-Y study

Background

Patients who experienced myocardial infarction (MI) at a young age are of special medical and socioeconomic interest; cardiovascular risk factor control to prevent recurrent events is crucial in this specific cohort.

Objectives

The purpose of the study was to evaluate long-term risk factor control in young MI-patients in clinical practice and investigate the effects of a modern intensive prevention program in a prospective randomized trial. In a genetic substudy it was analyzed if prevention effects were depending on individual genetic risk.

Methods

Patients who had MI at age of ≤45 years were revisited after a mean period of 5.7±4.0 years to evaluate long-term risk factor control. Furthermore a 12-months intensive prevention program in young MI-patients (IPP-Y), coordinated by non-physician prevention assistants and including personal teachings, telephone contacts, clinical and telemetric control of risk factors, was compared to usual care in a randomized trial. Primary endpoint of the randomized trial was prevention success, defined as improvement of one of the risk factors smoking, LDL cholesterol or physical inactivity without deterioration of the others. As the opposite prevention failure was defined as deterioration of one of the risk factors without improvement of the others. Genetic risk was assessed by polygenetic risk scores, based on 163 SNPs.

Results

Only a minority of the 277 young patients after MI achieved guideline-recommended risk factor targets at long-term follow-up visits: mean body mass index was 29.9±5.1 kg/m2, just 14.8% had a body mass index <25 kg/m2. More than one third (38.3%) were persistent or recurrent smokers. Mean LDL cholesterol level was 94±38 mg/dl, only 27.1% of the patients achieved LDL cholesterol levels <70 mg/dl.

However, the long-term prevention program IPP-Y led to a higher rate of the primary endpoint prevention success (IPP-Y: 49% vs. UC: 27%, p<0.05) and a lower rate of prevention failure (IPP-Y: 15% vs. UC: 38%, p<0.05) compared to usual care after 12 months (see figure). Telemetric control of risk factors as part of the prevention program was used by 71.4% of the patients.

In the genetic subanalysis prevention effects were found in both, patients with high genetic risk as well as patients with low genetic risk assessed by polygenetic risk scores (p=0.79 high vs. low genetic risk).

Effects of IPP-Y during 12 months

Conclusions

To our knowledge this is the first study on young patients with MI that demonstrates insufficient long-term risk factor control in clinical practice and significant effects of an intensive prevention program. Prevention effects were independent from individual genetic risk.

Acknowledgement/Funding

This work was supported by the Stiftung Bremer Herzen, Bremen, Germany and the Stiftung Bremer Wertpapierbörse, Bremen, Germany

P2660Definition of clinically relevant thresholds of acute kidney injury in patients with ST-elevation myocardial infarctions undergoing primary percutaneous coronary interventions

Background

Although the clinical importance of deteriorating kidney function in patients with ST-elevation-myocardial infarctions (STEMI) on overall prognosis is generally accepted, there is conflicting evidence on the importance of small changes in renal function. Aim of the present study was to calculate clincially relevant thresholds for deterioration of renal function after STEMI.

Methods

From a large registry of patients with STEMI renal function was estimated calculating the glomerular filtration rate (GFR in ml/min/1.73 m2) with the CKD-EPI-equation. To assess acute kidney injury the ratio GFR (at peak creatinine))/ GFR (at admission) was calculated for each patient (with 1 representing no change). Patients were graded by GFR-reduction and assigned to 11 groups (G1 to G11) each representing 5% intervals.

Results

Of 6583 patients admitted with STEMI between 2006–2017 3518 (53%) had no change or a change <5% during hospital stay (G1) while 161 (3%) showed a decrease in GFR of ≥50% (G11). The rest of the patients could be attributed to G2- G10 (table). There was a pronounced correlation between extent of GFR-reduction and peak creatine kinase (indicating size of STEMI, r2=0.785; G1: 1521±1684 U/l vs. G11: 2885±2943 U/l, p<0.01) as well as left-ventricular ejection fraction (LVEF) (r2=0.79; G1: 50.9±9% vs. G11: 41.4±10%, p<0.01). However, no such correlation could be detected between GFR-reduction and amount of contrast media (CM) applied (r2=0.05, G1: 141±60 ml vs. G11: 139±61 ml, p=0.5). Analysis of outcome-data (1-year-mortality and major adverse cardiovascular and cerebrovascular events (MACCE: death, stroke, re-infarction)) revealed, that beneath a threshold of 25% deterioration of renal function did not significantly impact prognosis, while higher degrees of deterioration led to a 7-fold increase in mortality and a 5-fold increase in MACCE-rates (table).

Impact of GFR-reduction on outcome Group G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 GFR-reduction (in %) 0–4 5 to 9 10 to 14 15 to 19 20 to 24 25 to 29 30 to 34 35 to 39 40 to 44 45 to 49 ≥50 Patients, n (%) 3518 (53) 881 (13) 717 (11) 492 (7) 327 (5) 196 (3) 119 (2) 88 (1) 48 (1) 36 (1) 161 (3) 1 year mortality (%) 7 4 5 8 7 15 20 22 39 43 50 1-year-MACCE (%) 12 8 8 12 10 19 27 27 49 49 52

Conclusions

These data from a large STEMI-registry show that small changes (less than 25%) in GFR did not significantly impact long-term outcome, while the impact was pronounced for all patients beyond that threshold. The degree of renal deterioration furthermore correlated with size of STEMI as well as reduction of LV-function after STEMI while no correlation to amount of contrast media could be found.

465Benefit of modern P2Y12-inhibitors on long-term prognosis in patients with ST-elevation myocardial infarction with and without advanced chronic kidney disease

Background

Current guidelines on the management of patients with ST-elevation myocardial infarction (STEMI) recommend the preferred use of the modern P2Y12-inhibitors ticagrelor or prasugrel regardless of the presence of chronic kidney disease (CKD), although patients with advanced stages of CKD were excluded from randomized trials. Aim of the present study was therefore to evaluate the potential benefit of modern P2Y12-inhibitors in patients with and without advanced renal disease at admission.

Methods

All patients admitted with STEMI between 2006–2017 from a large german heart center treated with primary percutaneous coronary intervention (PCI) entered analysis. Initial CKD was estimated with the initial glomerular filtration rate (GFR), calculated with the CKD-EPI-equation, assigning them to the groups G1-G5.

Results

Of 7227 patients with STEMI and primary PCI 2669 (37%) showed no relevant reduction in GFR at admission (≥90 ml/min/1.73 m2, G1), 2976 pts. (41%), a slight reduction (GFR 60–89 ml/min/1.73 m2, G2), 880 pts. (12%) a moderate reduction (GFR 45–59 ml/min/1.73 m2, G3a) and 702 pts. (10%) a moderate to severe reduction (GFR<45 ml/min 1.73 m2, G3b-G5). Pts. with more advanced stages of CKD were on average older (G1: 55±11 years, G2: 66±12 years, G3a: 72±12 years, G3b-G5: 75±11 years, p<0.01) and more likely to be female (G1: 19%, G2: 26%, G3a: 40%, G3b-G5: 48%, p<0.01). Prasugrel/ticagrelor were less often given instead of clopidogrel in patients with advanced CKD (G1: 70%, G2: 45%, G3a: 31%, G3b-G5: 32%, p<0.01). The use of ticagrelor/prasugrel was associated with a reduction in 1-year-MACCE (major adverse cardio- and cerebrovascular events)-rates in patients with no/low-grade-CKD (G1-G2), while no significant reduction in MACCE could be observed for patients with moderate to severe CKD (table). Furthermore, CKD was associated with an elevation in severe bleeding events within 1 year (G1: 1%, G2: 3%, G3a: 5%, G3b-G5: 6%, p<0.01).

Impact of CKD-stage on outcome CKD-stage G1 CKD-stage G2 CKD-stage G3a CKD-stage G3b-G5 1-year-MACCE-rate (%) Ticagrelor/prasugrel 4.5 11.0 27.4 47.3 Clopidogrel 9.9 15.6 26.6 50.4 Significance <0.01 <0.01 0.6 0.7

Conclusions

These data from a large STEMI-registry demonstrate, that modern P2Y12-inhibitors were less often used in patients with CKD and their benefit regarding MACCE disappeared in advanced stages of CKD while bleeding rates increased. These results underline the special role of patients with advanced stage-CKD in STEMI and the necessity of specialized randomized trials for these patients.

Design and implementation of a low temperature, inductance based high frequency alternating current susceptometer

We report on the implementation of an induction based, low temperature, high frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz and at temperatures between 2 K and 300 K. Careful balancing of the detection coils and calibration allow a sample magnetic moment resolution of 5 × 10^-10 Am² at 1 MHz. We discuss the design and characterization of the susceptometer and explain the calibration process. We also include some example measurements on the spin ice material CdEr₂S₄ and iron oxide based nanoparticles to illustrate functionality.

From clock to functional pacemaker

In mammals, the central pacemaker that coordinates 24‐hr rhythms is located in the suprachiasmatic nucleus (SCN). Individual neurons of the SCN have a molecular basis for rhythm generation and hence, they function as cell autonomous oscillators. Communication and synchronization among these neurons are crucial for obtaining a coherent rhythm at the population level, that can serve as a pace making signal for brain and body. Hence, the ability of single SCN neurons to produce circadian rhythms is equally important as the ability of these neurons to synchronize one another, to obtain a bona fide pacemaker at the SCN tissue level. In this chapter we will discuss the mechanisms underlying synchronization, and plasticity herein, which allows adaptation to changes in day length. Furthermore, we will discuss deterioration in synchronization among SCN neurons in aging, and gain in synchronization by voluntary physical activity or exercise.

Uncovering functional signature in neural systems via random matrix theory

Neural systems are organized in a modular way, serving multiple functionalities. This multiplicity requires that both positive (e.g. excitatory, phase-coherent) and negative (e.g. inhibitory, phase-opposing) interactions take place across brain modules. Unfortunately, most methods to detect modules from time series either neglect or convert to positive, any measured negative correlation. This may leave a significant part of the sign-dependent functional structure undetected. Here we present a novel method, based on random matrix theory, for the identification of sign-dependent modules in the brain. Our method filters out both local (unit-specific) noise and global (system-wide) dependencies that typically obfuscate the presence of such structure. The method is guaranteed to identify an optimally contrasted functional 'signature', i.e. a partition into modules that are positively correlated internally and negatively correlated across. The method is purely data-driven, does not use any arbitrary threshold or network projection, and outputs only statistically significant structure. In measurements of neuronal gene expression in the biological clock of mice, the method systematically uncovers two otherwise undetectable, negatively correlated modules whose relative size and mutual interaction strength are found to depend on photoperiod.

The influence of neuronal electrical activity on the mammalian central clock metabolome

INTRODUCTION

Most organisms display circadian rhythms in physiology and behaviour. In mammals, these rhythms are orchestrated by the suprachiasmatic nucleus (SCN). Recently, several metabolites have emerged as important regulators of circadian timekeeping. Metabolomics approaches have aided in identifying some key metabolites in circadian processes in peripheral tissue, but methods to routinely measure metabolites in small brain areas are currently lacking.

OBJECTIVE

The aim of the study was to establish a reliable method for metabolite quantifications in the central circadian clock and relate them to different states of neuronal excitability.

METHODS

We developed a method to collect and process small brain tissue samples (0.2 mm³), suitable for liquid chromatography-mass spectrometry. Metabolites were analysed in the SCN and one of its main hypothalamic targets, the paraventricular nucleus (PVN). Tissue samples were taken at peak (midday) and trough (midnight) of the endogenous rhythm in SCN electrical activity. Additionally, neuronal activity was altered pharmacologically.

RESULTS

We found a minor effect of day/night fluctuations in electrical activity or silencing activity during the day. In contrast, increasing electrical activity during the night significantly upregulated many metabolites in SCN and PVN.

CONCLUSION

Our method has shown to produce reliable and physiologically relevant metabolite data from small brain samples. Inducing electrical activity at night mimics the effect of a light pulses in the SCN, producing phase shifts of the circadian rhythm. The upregulation of metabolites could have a functional role in this process, since they are not solely products of physiological states, they are significant parts of cellular signalling pathways.

Chloride cotransporter KCC2 is essential for GABAergic inhibition in the SCN

One of the principal neurotransmitters of the central nervous system is GABA. In the adult brain, GABA is predominantly inhibitory, but there is growing evidence indicating that GABA can shift to excitatory action depending on environmental conditions. In the mammalian central circadian clock of the suprachiasmatic nucleus (SCN) GABAergic activity shifts from inhibition to excitation when animals are exposed to long day photoperiod. The polarity of the GABAergic response (inhibitory versus excitatory) depends on the GABA equilibrium potential determined by the intracellular Cl- concentration ([Cl-]i). Chloride homeostasis can be regulated by Cl- cotransporters like NKCC1 and KCC2 in the membrane, but the mechanisms for maintaining [Cl-]i are still under debate. This study investigates the role of KCC2 on GABA-induced Ca2+ transients in SCN neurons from mice exposed to different photoperiods. We show for the first time that blocking KCC2 with the newly developed blocker ML077 can cause a shift in the polarity of the GABAergic response. This will increase the amount of excitatory responses in SCN neurons and thus cause a shift in excitatory/inhibitory ratio. These results indicate that KCC2 is an essential component in regulating [Cl-]i and the equilibrium potential of Cl- and thereby determining the sign of the GABAergic response. Moreover, our data suggest a role for the Cl- cotransporters in the switch from inhibition to excitation observed under long day photoperiod.

Effects of an intensive long-term prevention programme after myocardial infarction - a randomized trial

BACKGROUND

Long-term risk factor control after myocardial infarction (MI) is currently inadequate and there is an unmet need for effective secondary prevention programmes.

DESIGN AND METHODS

It was the aim of the study to compare a 12-month intensive prevention programme (IPP), coordinated by prevention assistants and including education sessions, telephone visits and telemetric risk factor control, with usual care after MI. Three hundred and ten patients were randomized to IPP vs. usual care one month after hospital discharge for MI in two German heart centres. Primary study endpoint was the IPP Prevention Score (0-15 points) quantifying global risk factor control.

RESULTS

Global risk factor control was strongly improved directly after MI before the beginning of the randomized study (30% increase IPP Prevention Score). During the 12-month course of the randomized trial the IPP Prevention Score was improved by a further 14.3% in the IPP group ( p < 0.001), while it decreased by 11.8% in the usual care group ( p < 0.001). IPP significantly reduced smoking, low-density lipoprotein cholesterol, systolic blood pressure and physical inactivity compared with usual care ( p < 0.05). Step counters with online documentation were used by the majority of patients (80%). Quality of life was significantly improved by IPP ( p < 0.05). The composite endpoint of adverse clinical events was slightly lower in the IPP group during 12 months (13.8% vs. 18.9%, p = 0.25).

CONCLUSIONS

A novel intensive prevention programme after MI, coordinated by prevention assistants and using personal teachings and telemetric strategies for 12 months, was significantly superior to usual care in providing sustainable risk factor control and better quality of life.