Aging and circadian disruption: causes and effects

Dynamic neuronal instability generates synaptic plasticity and behavior: Insights from Drosophila sleep

How do neurons encode the information that underlies cognition, internal states, and behavior? This review focuses on the neural circuit mechanisms underlying sleep in Drosophila and, to illustrate the power of addressing neural coding in this system, highlights a specific circuit mediating the circadian regulation of sleep quality. This circuit exhibits circadian cycling of sleep quality, which depends solely on the pattern (not the rate) of spiking. During the night, the stability of spike waveforms enhances the reliability of spike timing in these neurons to promote sleep quality. During the day, instability of the spike waveforms leads to uncertainty of spike timing, which remarkably produces synaptic plasticity to induce arousal. Investigation of the molecular and biophysical basis of these changes was greatly facilitated by its study in Drosophila, revealing direct connections between genes, molecules, spike biophysical properties, neural codes, synaptic plasticity, and behavior. Furthermore, because these patterns of neural activity change with aging, this model system holds promise for understanding the interplay between the circadian clock, aging, and sleep quality. It is proposed here that neurophysiological investigations of the Drosophila brain present an exceptional opportunity to tackle some of the most challenging questions related to neural coding.

The association between bedtime and cardiac autonomic control in community-dwelling older adults - The Yilan study, Taiwan

This study aimed to investigate the association between bedtime and cardiac autonomic function in older adults. This cross-sectional study included community-dwelling older adults aged ≥ 65 years. Self-reported bedtime was categorized as early (< 21:30), intermediate (21:30-22:30), and late (> 22:30). Cardiac autonomic function was evaluated by HRV. The lowest tertiles for each HRV parameter were defined as unhealthy indicators. A total of 3,729 individuals participated, with mean age of 76.3 ± 6.6 years. After controlling for various covariates, late bedtime was associated with a lower risk for unhealthy total power [Odds ratio (OR) = 0.74; 95% confidence interval (CI) = 0.59-0.93] and low frequency power (OR = 0.69, 95% CI = 0.55-0.87) than intermediate bedtime. In contrast, early bedtime was correlated with a higher risk of poor total power (OR = 1.23, 95% CI: 1.05-1.45) and high frequency power (OR = 1.18, 95% CI = 1.00-1.39). When further specifying sleep duration and physical disability into the regression models, the inverse association between late bedtime and unhealthy HRV remained; however, the association between early bedtime and HRV disappeared. Accordingly, we concluded that in terms of cardiac autonomic function, early bedtime in older adults is not necessarily beneficial for their health outcomes, whereas late bedtime may not be detrimental.Abbreviations: ADL: activity of daily living; BMI: body mass index; CI: confidence interval; GARS: the Groningen Activity Restriction Scale; HADS: The Hospital Anxiety and Depression Scale; HF: high frequency power; HRV: heart rate variability; LF: low frequency power; LF/HF: low frequency to high frequency ratio; OR: odds ratios; TP: total power.

The prevalence of sleep loss and sleep disorders in young and old adults

The ability to sleep declines with age. The National Sleep Foundation, USA has recommended a minimum sleep amount for all ages. Individuals who experience sleep lesser than the recommended amount could be sleep-deprived. Several factors like stress, altered circadian cycle, medical conditions, etc. cause sleep deficiency. Almost 50-60 % of elderly population suffer from sleep disorders such as sleep apnea, restless legs syndrome, REM sleep behavior disorder, etc. Chronic sleep deprivation may further lead to the development of diseases such as Alzheimer's and Parkinson's. This paper reviews the prevalence of sleep disorders and consequences of sleep loss in young and old adults.

A protective effect of morning radiotherapy on acute skin toxicity in patients with breast cancer: A prospective cohort study

The focus of this prospective cohort study was to evaluate the risk factors of severe acute skin toxicity (grade ≥2) in 100 patients with breast cancer (BC) during radiotherapy (RT).The patients were evaluated weekly during RT and 3 months after treatment. The endpoint included the occurrence of skin toxicity grade ≥2, according to Radiation Therapy Oncology Group (RTOG). Survival analysis was conducted by univariate and multivariate Cox regression analysis.In the multivariate analysis, RT in the afternoon (0-3 pm) (hazard ratios [HR] = 1.566, P = .042) was significantly associated with the early occurrence of skin toxicity, indicating a potential effect of chronotherapy related to this adverse event. In the univariate and multivariate analysis, skin phototype moderate brown (HR = 1.586, P = .042; HR = 1.706, P = .022, respectively) and dark brown or black (HR = 4.517, P < .001; HR = 5.336, P < 0.001, respectively) was significantly associated with the skin toxicity. Tangential field separation >21 cm (HR = 2.550, P = .009, HR = 2.923, P = .003), in women that were submitted to conservative surgery indicates indirectly that large breast size was also significantly associated with skin toxicity.Women with large breasts and dark brown or black skin should be followed more carefully during RT, which should be undergone in the morning, especially when submitted to conventional RT techniques, common in developing countries.

The gut microbiota and nervous system: Age-defined and age-defying

Even healthy older adults experience gastrointestinal (GI) and neurological changes. In fact, the aging process of these two systems are interrelated due the extensive, multifaceted communication network connecting them, termed the gut-brain axis. Age-related modification of the GI environment can influence the bacterial species that survive and thrive there. Additionally, the lifestyle common to older adults in the West, including sedentariness, polypharmacy, and a poor diet, can compound the effect of aging on the GI tract, gut microbiota, and nervous system. Emerging animal and human findings suggest that GI organisms play a major role in gut-brain communication, ultimately shaping neurological aging trajectories by either helping to maintain nervous system function into late life or promoting pathology. Aging and age-related behaviors help to define the gut microbiota's composition and function, but, conversely, the gut microbiota may help to determine late-life functionality and may be harnessed to limit the prevalence of steep neurological decline and diseases. Focusing primarily on clinical research, this review first defines the gut-brain axis, then details age-related GI and nervous system changes, and discusses the impact of age-related lifestyle factors on the GI and nervous systems. The remainder of this review describes cutting-edge research that positions the gut microbiota as an arbiter of age-related neurological decline.

The impact of the 24-h movement spectrum on vascular remodeling in older men and women: a review

Aging is associated with increased risk of cardiovascular and cerebrovascular events, which are preceded by early, negative remodeling of the vasculature. Low physical activity is a well-established risk factor associated with the incidence and development of disease. However, recent physical activity literature indicates the importance of considering the 24-h movement spectrum. Therefore, the purpose of this review was to examine the impact of the 24-h movement spectrum, specifically physical activity (aerobic and resistance training), sedentary behavior, and sleep, on cardiovascular and cerebrovascular outcomes in older adults, with a focus on recent evidence (<10 yr) and sex-based considerations. The review identifies that both aerobic training and being physically active (compared with sedentary) are associated with improvements in endothelial function, arterial stiffness, and cerebrovascular function. Additionally, there is evidence of sex-based differences in endothelial function: a blunted improvement in aerobic training in postmenopausal women compared with men. While minimal research has been conducted in older adults, resistance training does not appear to influence arterial stiffness. Poor sleep quantity or quality are associated with both impaired endothelial function and increased arterial stiffness. Finally, the review highlights mechanistic pathways involved in the regulation of vascular and cerebrovascular function, specifically the balance between pro- and antiatherogenic factors, which mediate the relationship between the 24-h movement spectrum and vascular outcomes. Finally, this review proposes future research directions: examining the role of duration and intensity of training, combining aerobic and resistance training, and exploration of sex-based differences in cardiovascular and cerebrovascular outcomes.

Disruptions of Circadian Rhythms and Thrombolytic Therapy During Ischemic Stroke Intervention

Several endogenous and exogenous factors interact to influence stroke occurrence, in turn contributing to discernable daily distribution patterns in the frequency and severity of cerebrovascular events. Specifically, strokes that occur during the morning tend to be more severe and are associated with elevated diastolic blood pressure, increased hospital stay, and worse outcomes, including mortality, compared to strokes that occur later in the day. Furthermore, disrupted circadian rhythms are linked to higher risk for stroke and play a role in stroke outcome. In this review, we discuss the interrelation among core clock genes and several factors contributing to ischemic outcomes, sources of disrupted circadian rhythms, the implications of disrupted circadian rhythms in foundational stroke scientific literature, followed by a review of clinical implications. In addition to highlighting the distinct daily pattern of onset, several aspects of physiology including immune response, endothelial/vascular and blood brain barrier function, and fibrinolysis are under circadian clock regulation; disrupted core clock gene expression patterns can adversely affect these physiological processes, leading to a prothrombotic state. Lastly, we discuss how the timing of ischemic onset increases morning resistance to thrombolytic therapy and the risk of hemorrhagic transformation.

Sex differences in subjective age-associated changes in sleep: a prospective elderly cohort study

Subjective age-associated changes in sleep (AACS) and sex differences in AACS have never been prospectively investigated in elderly populations. We compared the AACS every 2 years over a total of 6 years between 4,686 community-dwelling healthy men and women aged 60 years or older who participated in the Korean Longitudinal Study on Cognitive Aging and Dementia. Sleep parameters including sleep duration, latency, and efficiency, mid-sleep time, daytime dysfunction, and overall subjective sleep quality were measured using the Pittsburgh Sleep Quality Index at baseline and at each follow-up. The effects of time and sex on subjective sleep parameters were analyzed using linear mixed-effects models. During the 6 years of follow-up, we observed that overall, sleep latency increased, while daytime dysfunction and sleep quality worsened. Significant sex differences in AACS was found, with women showing shortened sleep duration, delayed mid-sleep time, and decreased sleep efficiency over 6 years. Sleep quality worsened in both groups but a more pronounced change was observed in women. Clinicians should be cautious in determining when to treat declared sleep disturbances in this population.

Is Sleep Associated with the S-Klotho Anti-Aging Protein in Sedentary Middle-Aged Adults? The FIT-AGEING Study

Sleep and Klotho have both been closely related to the ageing process, both playing a substantial role in the endocrine and immune systems and, thereby, in oxidative stress and chronic inflammation. However, there are no studies elucidating the relationship between sleep and Klotho. Therefore, this study investigated the association of sleep quantity and quality with the shed form of the α-Klotho gene (S-Klotho plasma levels) in sedentary middle-aged adults. A total of 74 volunteers (52.7% women; aged 53.7 ± 5.1) were recruited for the present study. Objective sleep quality parameters (total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE)) were determined using a wrist-worn accelerometer over seven consecutive days, and the subjective sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI; higher scores indicate worse sleep quality). The S-Klotho plasma levels were measured in the ethylenediaminetetraacetic acid plasma using a solid-phase sandwich enzyme-linked immunosorbent assay. Objective sleep parameters were associated with the S-Klotho plasma levels only after including the age, fat mass percentage, and lean mass index as covariates. A direct relationship was observed between the subjective sleep quality (inverse of PSQI scores) and the S-Klotho plasma levels in sedentary middle-aged adults. Improving sleep quantity and quality could be considered an anti-aging therapeutic approach for the prevention, slowing, and even reversal of the physiological decline and degenerative pathologies that are certainly related to the aging process.

The spleen mediates chronic sleep restriction-mediated enhancement of LPS-induced neuroinflammation, cognitive deficits, and anxiety-like behavior

Chronic sleep restriction promotes neuroinflammation and cognitive deficits in neurodegenerative and neurobehavioral diseases. The spleens of mice exposed to chronic and repeated psychological stress serve as a reservoir of inflammatory myeloid cells that are released into the blood and brain following secondary acute stress. Here, we tested whether chronic and repeated short-term sleep restriction (CRSR) would exacerbate lipopolysaccharide (LPS)-induced neuroinflammation, cognitive deficits, and anxiety-like behavior in a spleen-dependent manner. LPS was administered to aged mice 14 days after exposure to CRSR consisting of three cycles of 7 days of sleep restriction with 7-day intervals in between. CRSR increased plasma proinflammatory cytokine levels, blood-brain barrier permeability, hippocampal proinflammatory cytokine levels, and transition of microglia to the M1 phenotype 24 h after LPS treatment. This in turn led to cognitive deficits and anxiety-like behavior. Interestingly, removal of the spleen 14 days prior to CRSR abrogated the enhancement of LPS-induced increases in systemic inflammation, neuroinflammation, cognitive deficits, and anxiety-like behavior. These data indicate that the spleen was essential for CRSR-induced exacerbation of LPS-induced brain damage.

Telomeres as Therapeutic Targets in Heart Disease

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Age-associated CVDs impose a great burden on current health systems. Despite the fact that current strong evidence supports the links among aging, telomere attrition, and CVDs, there is no clear direction for the development of telomere therapeutics against CVDs.

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This review focuses on immune modulation, CHIP, pharmaceutical interventions, and gene therapy for their therapeutic roles in age-associated CVDs.

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The future goal of telomere cardiovascular therapy in young subjects is to prevent senescence and diseases, whereas in older adult subjects, the goal is restoration of cardiovascular functions. Further studies on the telomere-CHIP-atherosclerosis axis may shed insights on how to achieve these 2 different therapeutic targets.

Telomeres are double-stranded repeats of G-rich tandem DNA sequences that gradually shorten with each cell division. Aging, inflammation, and oxidative stress accelerate the process of telomere shortening. Telomerase counteracts this process by maintaining and elongating the telomere length. Patients with atherosclerotic diseases and cardiovascular risk factors (e.g., smoking, obesity, sedentary lifestyle, and hypertension) have shorter leukocyte telomere length. Following myocardial infarction, telomerase expression and activity in cardiomyocytes and endothelial cells increase significantly, implying that telomerase plays a role in regulating tissue repairs in heart diseases. Although previous studies have focused on the changes of telomeres in heart diseases and the telomere length as a marker for aging cardiovascular systems, recent studies have explored the potential of telomeres and telomerase in the treatment of cardiovascular diseases. This review discusses the significant advancements of telomere therapeutics in gene therapy, atherosclerosis, anti-inflammation, and immune modulation in patients with cardiovascular diseases.

Loss of Prune in Circadian Cells Decreases the Amplitude of the Circadian Locomotor Rhythm in Drosophila

The circadian system, which has a period of about 24 h, is import for organismal health and fitness. The molecular circadian clock consists of feedback loops involving both transcription and translation, and proper function of the circadian system also requires communication among intracellular organelles. As important hubs for signaling in the cell, mitochondria integrate a variety of signals. Mitochondrial dysfunction and disruption of circadian rhythms are observed in neurodegenerative diseases and during aging. However, how mitochondrial dysfunction influences circadian rhythm is largely unknown. Here, we report that Drosophila prune (pn), which localizes to the mitochondrial matrix, most likely affects the function of certain clock neurons.Deletion of pn in flies caused decreased expression of mitochondrial transcription factor TFAM and reductions in levels of mitochondrial DNA, which resulted in mitochondrial dysfunction. Loss of pn decreased the amplitude of circadian rhythms.In addition, we showed that depletion of mtDNA by overexpression of a mitochondrially targeted restriction enzyme mitoXhoI also decreased the robustness of circadian rhythms. Our work demonstrates that pn is important for mitochondrial function thus involved in the regulation of circadian rhythms.

The role of melatonin, a multitasking molecule, in retarding the processes of ageing

Biological ageing is generally accompanied by a gradual loss of cellular functions and physiological integrity of organ systems, the consequential enhancement of vulnerability, senescence and finally death. Mechanisms which underlie ageing are primarily attributed to an array of diverse but related factors including free radical-induced damage, dysfunction of mitochondria, disruption of circadian rhythms, inflammaging, genomic instability, telomere attrition, loss of proteostasis, deregulated sensing of nutrients, epigenetic alterations, altered intercellular communication, and decreased capacity for tissue repair. Melatonin, a prime regulator of human chronobiological and endocrine physiology, is highly reputed as an antioxidant, immunomodulatory, antiproliferative, oncostatic, and endocrine-modulatory molecule. Interestingly, several recent reports support melatonin as an anti-ageing agent whose multifaceted functions may lessen the consequences of ageing. This review depicts four categories of melatonin's protective effects on ageing-induced molecular and structural alterations. We also summarize recent findings related to the function of melatonin during ageing in various tissues and organs.

Identification of pathway-based recurrence-associated signatures in optimally debulked patients with serous ovarian cancer

Serous ovarian cancer (SOC) is the most common form of the histological subtype of epithelial ovarian cancer, with the worst clinical outcome. Despite improvements in surgery and chemotherapy, most patients with SOC experience recurrence within 12-18 months of first-line treatment. Current studies are unable to robustly predict the recurrence of SOC, and more accurate predictive models are urgently required. We have, therefore, developed a novel pathway-structured model to predict the recurrence of SOC. We trained the model on a set of 333 patients and validated it in 3 diversified validation datasets of 403 patients. Genes significantly associated with recurrence within each pathway were identified using a Cox proportional hazards model based on LASSO estimation in the training dataset. Next, a pathway-structured scoring matrix was obtained after computation of the prognostic score for each pathway by fitting to the Cox proportional hazards model. With the pathway-structure scoring matrix as an input, the pathway-based recurrent signatures were identified using the Cox proportional hazards model based on LASSO estimation and the significant pathway-based signatures were externally validated in 3 independent datasets. Meanwhile, our pathway-structured model was compared with a commonly used gene-based model. Our results revealed that our 12 pathway-based signatures successfully predicted the recurrence of SOC with high accuracy in the training dataset and in the 3 validation datasets. Moreover, our pathway-structured model was superior to the gene-based model in 4 datasets. The pathways selected in our study will provide new insights into the pathogenesis and clinical treatments of SOC.

Insomnia in the Ageing Population: Characterisation and Non-Pharmacological Treatment Strategies

Sleep problems represent a worldwide health concern among older adults, with an increasing prevalence of multimorbid conditions and a decreased quality of life. However, most elderly patients are not correctly diagnosed due to numerous confounding variables (e.g., medical and psychiatric disorders, polypharmacy, and psychosocial factors) affecting sleep and the confusion regarding the differential diagnosis in older adults between normal changes in sleep pattern as a result of ageing and sleep disorders. There are normal changes to the sleep architecture throughout the lifespan, and sleep disorders are not part of the ageing process; however, there are several sleep disorders that affect older adults. The most prevalent sleep disorder is insomnia, which is found in different forms and affects approximately 30–50% of the older adult population. The treatment strategies for sleep disorders are multivariate, with prescriptions of pharmacological treatments being the most common method among healthcare professionals; however, there is strong evidence that non-pharmacological treatments have better long-term effects. The aim of this review is to explain the difference between sleep disorders and sleep alterations as a result of ageing, to characterise insomnia in older adults, and, finally, to present the different effective non-pharmacological possibilities, accompanied by evidence, for the treatment of insomnia in older adults.

The nuclear receptor and clock gene REV-ERBα regulates cigarette smoke-induced lung inflammation

REV-ERBα is a nuclear heme receptor, transcriptional repressor and critical component of the molecular clock that drives daily rhythms of metabolism. Evidence reveals that REV-ERBα also plays an important regulatory role in clock-dependent lung physiology and inflammatory responses. We hypothesize that cigarette smoke (CS) exposure influences REV-ERBα abundance in the lungs, facilitating a pro-inflammatory phenotype. To determine the impact of REV-ERBα activation in the CS-induced inflammatory response we treated primary human small airway epithelial cells (SAECs) with CS extract (CSE) or lipopolysaccharide (LPS) in the absence or presence of pre-treatment with the REV-ERBα agonist GSK 4112. We also exposed adult C57BL/6J (WT) and Rev-erbα global KO mice to CS (10 and 30 days) and measured pro-inflammatory cytokine release. Our data reveal that pre-treatment with GSK 4112 reduced CSE/LPS induced pro-inflammatory cytokines release from both SAECs and mouse lung fibroblasts (MLFs). Furthermore, REV-ERBα KO mice show a greater inflammatory response to 10 and 30 days of CS, including increased neutrophil lung influx, pro-inflammatory cytokine (IL-6, MCP-1 and KC) release, and pro-senescence marker (p16) when compared to WT mice. These data demonstrate that REV-ERBα is a critical regulator of CS-induced lung inflammatory responses.

Young children with Down syndrome show normal development of circadian rhythms, but poor sleep efficiency: a cross-sectional study across the first 60 months of life

Objectives

To evaluate sleep consolidation and circadian activity rhythms in infants and toddlers with Down syndrome (DS) under light and socially entrained conditions within a familiar setting. Given previous human and animal data suggesting intact circadian regulation of melatonin across the day and night, it was hypothesized that behavioral indices of circadian rhythmicity would likewise be intact in the sample with DS.

Methods

A cross-sectional study of 66 infants and young children with DS, aged 5–67 months, and 43 typically developing age-matched controls. Sleep and measures of circadian robustness or timing were quantified using continuous in-home actigraphy recordings performed over seven days. Circadian robustness was quantified via time series analysis of rest-activity patterns. Phase markers of circadian timing were calculated alongside these values. Sleep efficiency was also estimated based on the actigraphy recordings.

Results

This study provided further evidence that general sleep quality is poor in infants and toddlers with DS, a population that has sleep apnea prevalence as high as 50% during the preschool years. Despite poor sleep quality, circadian rhythm and phase were preserved in children with DS and displayed similar developmental trajectories in cross-sectional comparisons with a typically developing (TD) cohort. In line with past work, lower sleep efficiency scores were quantified in the group with DS relative to TD children. Infants born with DS exhibited the worst sleep fragmentation; however, in both groups, sleep efficiency and consolidation increased across age. Three circadian phase markers showed that 35% of the recruitment sample with DS was phase-advanced to an earlier morning schedule, suggesting significant within-group variability in the timing of their daily activity rhythms.

Conclusions

Circadian rhythms of wake and sleep are robust in children born with DS. The present results suggest that sleep fragmentation and any resultant cognitive deficits are likely not confounded by corresponding deficits in circadian rhythms.

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Circadian activity rhythms are robust in young children with Down syndrome.

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Early morning activity is phase-advanced in a subgroup.

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Infants with Down syndrome show significant sleep fragmentation.

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Sleep efficiency improves with age in children with Down syndrome, but still lags the trajectory seen in typical development.

Positive association between physical activity and PER3 expression in older adults

The circadian clock regulates many physiological functions including physical activity and feeding patterns. In addition, scheduled exercise and feeding themselves can affect the circadian clock. The purpose of the present study was to investigate the relationship between physical/feeding activity and expression of clock genes in hair follicle cells in older adults. Twenty adult men (age, 68 ± 7 years, mean ± SE) were examined in this cross-sectional study. Prior to hair follicle cell collection, the participants were asked to wear a uniaxial accelerometer for one week. The timings of breakfast, lunch, and dinner were also recorded. Hair follicle cells were then collected over a 24 h period at 4 h intervals. The amplitude of PER3 expression was positively correlated with moderate and vigorous physical activity (r = 0.582, p = 0.007) and peak oxygen uptake (r = 0.481, p = 0.032), but these correlations were not observed for NR1D1 or NR1D2. No association was noted between meal times and the amplitude or the acrophase for any of these three clock genes. These findings suggest that rhythmic expression of the circadian clock gene PER3 is associated with the amount of daily physical activity and physical fitness in older adults.

Circadian Dysregulation in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder that affects over one million individuals in the US alone. PD is characterized by a plethora of motor and non-motor manifestations, resulting from a progressive degeneration of dopaminergic neurons and disbalance of several other neurotransmitters. A growing body of evidence points to significant alterations of the circadian system in PD. This is not surprising given the pivotal role that dopamine plays in circadian regulation as well as the role of circadian influences in dopamine metabolism. In this review we present basic and clinical investigations that examined the function of the circadian system in PD.

Circadian genes Per1 and Per2 increase radiosensitivity of glioma in vivo

Per1 and Per2 play a key role in regulating the circadian rhythm in mammals. We report here that although both genes were expressed with a circadian rhythm in glioma and normal brain tissue in rats, their expression profiles differed in the two types of tissue. In addition, high expression of Per1 and Per2 in glioma tissue was associated with increased sensitivity to x-irradiation. No such sensitizing effect was observed in normal tissue. Our results suggest that Per1 and Per2 expression may increase the efficacy of radiotherapy against glioma by promoting apoptosis.

Differences in toxicity and outcome associated with circadian variations between patients undergoing daytime and evening radiotherapy for prostate adenocarcinoma

This retrospective study tested the hypothesis that disease control and treatment-related toxicity in patients undergoing high-dose radiotherapy (HDRT) for prostate cancer varies in a circadian manner. Patients with localized prostate adenocarcinoma receiving HDRT (median 78 Gy) to the prostate and involved seminal vesicle(s) without elective pelvic irradiation were divided into a daytime treatment (before 5 PM) group (n = 267) and evening treatment (after 5 PM) group (n = 142). Biochemical failure (Phoenix definition), acute and late gastrointestinal (GI) and genitourinary toxicities (Common Terminology Criteria for Adverse Events version 4), biochemical failure-free survival (BFFS) and freedom from late toxicity were assessed. Analyses were performed by binary logistic regression and Cox proportional hazard regression. The median follow-up was 68 months, and 75% of patients were ≥70 years old. Evening HDRT was significantly associated with worse freedom from ≥grade 2 late GI complications (hazard ratio = 2.96; p < 0.001). The detrimental effect of evening HDRT was significant in patients older than 70 years old (p < 0.001) but not in younger patients (p = 0.63). In a subgroup of propensity score-matched cohort with T2b-T3 disease (n = 154), the 5-year BFFS was worse in the evening group than the daytime group (72% vs. 85%, hazard ratio = 1.95, p = 0.05). Our study indicates that evening HDRT may lead to more GI complications, especially in older patients, and worse BFFS in patients with T2b-T3 disease.

Human peripheral clocks: applications for studying circadian phenotypes in physiology and pathophysiology

Most light-sensitive organisms on earth have acquired an internal system of circadian clocks allowing the anticipation of light or darkness. In humans, the circadian system governs nearly all aspects of physiology and behavior. Circadian phenotypes, including chronotype, vary dramatically among individuals and over individual lifespan. Recent studies have revealed that the characteristics of human skin fibroblast clocks correlate with donor chronotype. Given the complexity of circadian phenotype assessment in humans, the opportunity to study oscillator properties by using cultured primary cells has the potential to uncover molecular details difficult to assess directly in humans. Since altered properties of the circadian oscillator have been associated with many diseases including metabolic disorders and cancer, clock characteristics assessed in additional primary cell types using similar technologies might represent an important tool for exploring the connection between chronotype and disease, and for diagnostic purposes. Here, we review implications of this approach for gathering insights into human circadian rhythms and their function in health and disease.

Wearable Monitoring of Physical Functioning and Disability Changes, Circadian Rhythms and Sleep Patterns in Nursing Home Residents

Sleep problems and disrupted circadian rhythms are common among older adults and may be associated with several health issues and physical functioning status. Wearable continuous monitoring of physical activity enables unobtrusive monitoring of circadian activity and sleep patterns. The objective of this retrospective study was to analyze whether physical functioning status (Activities of Daily Living assessment of Resident Assessment Instrument) is associated with diurnal activity rhythm and sleep patterns measured with wearable activity sensor in nursing home residents during their normal daily life. Continuous activity data were collected by the wearable sensor from 16 nursing home residents (average age of 90.7 years, seven demented subjects, one female) in their daily life over several months (12-18 months). The subjects' physical activity and sleep were quantified by several parameters from the activity data. In the cross-sectional analysis, physical functioning status was associated with the strength (RHO = 0.78, ) and the stability (RHO = 0.72, ) of the activity rhythm when the level of dementia was not controlled. In the longitudinal analysis (12-18 months), at an individual level the activity rhythm indices and activity level had the strongest correlations with changes in physical functioning but the associations were to some extent individual. In these long-term case recordings, decrease in the physical functioning was most strongly associated with decreasing levels of activity, stability, and strength of the activity rhythm, and with increasing fragmentation of rhythm and daytime passivity. Daily wearable monitoring of physical activity may hence reveal information about functioning state and health of older adults. However, since the changes in activity patterns implying changes in physical functioning status may not be consistent between the individuals, a multivariate approach is recommended for monitoring of these changes by continuous physical activity measurement.

The circadian rhythm controls telomeres and telomerase activity

Circadian clocks are fundamental machinery in organisms ranging from archaea to humans. Disruption of the circadian system is associated with premature aging in mice, but the molecular basis underlying this phenomenon is still unclear. In this study, we found that telomerase activity exhibits endogenous circadian rhythmicity in humans and mice. Human and mouse TERT mRNA expression oscillates with circadian rhythms and are under the control of CLOCK-BMAL1 heterodimers. CLOCK deficiency in mice causes loss of rhythmic telomerase activities, TERT mRNA oscillation, and shortened telomere length. Physicians with regular work schedules have circadian oscillation of telomerase activity while emergency physicians working in shifts lose the circadian rhythms of telomerase activity. These findings identify the circadian rhythm as a mechanism underlying telomere and telomerase activity control that serve as interconnections between circadian systems and aging.

Circadian arrhythmia dysregulates emotional behaviors in aged Siberian hamsters

Emotional behaviors are influenced by the circadian timing system. Circadian disruptions are associated with depressive-like symptoms in clinical and preclinical populations. Circadian rhythm robustness declines markedly with aging and may contribute to susceptibility to emotional dysregulation in aged individuals. The present experiments used a model of chronic circadian arrhythmia generated noninvasively, via a series of circadian-disruptive light treatments, to investigate interactions between circadian desynchrony and aging on depressive- and anxiety-like behaviors, and on limbic neuroinflammatory gene expression that has been linked with emotionality. We also examined whether a social manipulation (group housing) would attenuate effects of arrhythmia on emotionality. In aged (14-18 months of age) male Siberian hamsters, circadian arrhythmia increased behavioral despair and decreased social motivation, but decreased exploratory anxiety. These effects were not evident in younger (5-9 months of age) hamsters. Social housing (3-5 hamsters/cage) abolished the effects of circadian arrhythmia on emotionality. Circadian arrhythmia alone was without effect on hippocampal or cortical interleukin-1β (IL-1β) and indoleamine 2,3-dioxygenase (Ido) mRNA expression in aged hamsters, but social housing decreased hippocampal IL-1β and Ido mRNAs. The data demonstrate that circadian disruption can negatively impact affective state, and that this effect is pronounced in older individuals. Although clear associations between circadian arrhythmia and constitutive limbic proinflammatory activity were not evident, the present data suggest that social housing markedly inhibits constitutive hippocampal IL-1β and Ido activity, which may contribute to the ameliorating effects of social housing on a number of emotional behaviors.

Dicer expression exhibits a tissue-specific diurnal pattern that is lost during aging and in diabetes

Dysregulation of circadian rhythmicity is identified as a key factor in disease pathogenesis. Circadian rhythmicity is controlled at both a transcriptional and post-transcriptional level suggesting the role of microRNA (miRNA) and double-stranded RNA (dsRNA) in this process. Endonuclease Dicer controls miRNA and dsRNA processing, however the role of Dicer in circadian regulation is not known. Here we demonstrate robust diurnal oscillations of Dicer expression in central and peripheral clock control systems including suprachiasmatic nucleolus (SCN), retina, liver, and bone marrow (BM). The Dicer oscillations were either reduced or phase shifted with aging and Type 2 diabetes. The decrease and phase shift of Dicer expression was associated with a similar decrease and phase shift of miRNAs 146a and 125a-5p and with an increase in toxic Alu RNA. Restoring Dicer levels and the diurnal patterns of Dicer-controlled miRNA and RNA expression may provide new therapeutic strategies for metabolic disease and aging-associated complications.

Food for thought: understanding the multifaceted nature of orexins

Orexins are a pair of hypothalamic neuropeptides that were discovered in the late 1990s and named initially for their ability to promote feeding. Subsequent studies have revealed the importance of orexins to a variety of physiological functions, including brown fat thermogenesis, sleep/wake cycles, physical activity, and cognition. We aim to elucidate the various roles of orexins and discuss how these multiple functions are interlinked. We explain that although the unique dual roles of orexins in increasing feeding while concomitantly elevating energy expenditure appear counterproductive, they are necessary for physiological scenarios during which simultaneous stimulation of energy expenditure and feeding occur, namely diet-induced thermogenesis and arousal from hibernation. The position of orexins at the interface between sleep/wake cycles, energy homeostasis, and environmental factors has important implications in the treatment of obesity.

Phase-shifting response to light in older adults

Age-related changes in circadian rhythms may contribute to the sleep disruption observed in older adults. A reduction in responsiveness to photic stimuli in the circadian timing system has been hypothesized as a possible reason for the advanced circadian phase in older adults. This project compared phase-shifting responses to 2 h of broad-spectrum white light at moderate and high intensities in younger and older adults. Subjects included 29 healthy young (25.1 ± 4.1 years; male to female ratio: 8: 21) and 16 healthy older (66.5 ± 6.0 years; male to female ratio: 5: 11) subjects, who participated in two 4-night and 3-day laboratory stays, separated by at least 3 weeks. Subjects were randomly assigned to one of three different time-points, 8 h before (-8), 3 h before (-3) or 3 h after (+3) the core body temperature minimum (CBTmin) measured on the baseline night. For each condition, subjects were exposed in a randomized order to 2 h light pulses of two intensities (2000 lux and 8000 lux) during the two different laboratory stays. Phase shifts were analysed according to the time of melatonin midpoint on the nights before and after light exposure. Older subjects in this study showed an earlier baseline phase and lower amplitude of melatonin rhythm compared to younger subjects, but there was no evidence of age-related changes in the magnitude or direction of phase shifts of melatonin midpoint in response to 2 h of light at either 2000 lux or 8000 lux. These results indicate that the acute phase-shifting response to moderate- or high-intensity broad spectrum light is not significantly affected by age.

Chronic mild sleep restriction accentuates contextual memory impairments, and accumulations of cortical Aβ and pTau in a mouse model of Alzheimer's disease

Age-associated dysregulation of sleep can be worsened by Alzheimer's disease (AD). AD and sleep restriction both impair cognition, yet it is unknown if mild chronic sleep restriction modifies the proteopathic processes involved in AD. The goal of this work was to test the hypothesis that sleep restriction worsens memory impairments, and amyloid β-peptide (Aβ) and pTau accumulations in the brain in a mouse model of AD, with a focus on a role for circulating glucocorticoids (GC). Male 3xTgAD mice were subjected to sleep restriction (SR) for 6h/day for 6 weeks using the modified multiple platform technique, and behavioral (Morris water maze, fear conditioning, open field) and biochemical (immunoblot) outcomes were compared to mice undergoing daily cage transfers (large cage control; LCC) as well as control mice that remained in their home cage (control; CTL). At one week, both LCC and SR mice displayed significant elevations in plasma corticosterone compared to CTL (p<0.002). By four weeks, SR mice displayed a two-fold increase in circulating corticosterone levels compared to CTL. Behavioral data indicated deficits in contextual and cued memory in SR mice that were not present for LCC or CTL (p<0.04). Both Aβ and pTau levels increased in the cortex of SR mice compared to CTL and LCC; however these changes were not noted in the hippocampus. Significant positive correlations between cortical Aβ and pTau levels and circulating corticosterone indicate a potential role for GCs in mediating behavioral and biochemical changes observed after sleep restriction in a mouse model of AD.

Exposure to light at night accelerates aging and spontaneous uterine carcinogenesis in female 129/Sv mice

The effect of the constant illumination on the development of spontaneous tumors in female 129/Sv mice was investigated. Forty-six female 129/Sv mice starting from the age of 2 mo were kept under standard light/dark regimen [12 h light (70 lx):12 hr dark; LD, control group], and 46 of 129/Sv mice were kept under constant illumination (24 h a day, 2,500 lx, LL) from the age of 5 mo until to natural death. The exposure to the LL regimen significantly accelerated body weight gain, increased body temperature as well as acceleration of age-related disturbances in estrous function, followed by significant acceleration of the development of the spontaneous uterine tumors in female 129/Sv mice. Total tumor incidence as well as a total number of total or malignant tumors was similar in LL and LD group (p > 0.05). The mice from the LL groups survived less than those from the LD group (χ ( 2) = 8.5; p = 0.00351, log-rank test). According to the estimated parameters of the Cox's regression model, constant light regimen increased the relative risk of death in female mice compared with the control (LD) group (p = 0.0041). The data demonstrate in the first time that the exposure to constant illumination was followed by the acceleration of aging and spontaneous uterine tumorigenesis in female 129/Sv mice.

Sleep disturbances in Alzheimer's and Parkinson's diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most common neurodegenerative disorders and exact a burden on our society greater than cardiovascular disease and cancer combined. While cognitive and motor symptoms are used to define AD and PD, respectively, patients with both disorders exhibit sleep disturbances including insomnia, hypersomnia and excessive daytime napping. The molecular basis of perturbed sleep in AD and PD may involve damage to hypothalamic and brainstem nuclei that control sleep-wake cycles. Perturbations in neurotransmitter and hormone signaling (e.g., serotonin, norepinephrine and melatonin) and the neurotrophic factor BDNF likely contribute to the disease process. Abnormal accumulations of neurotoxic forms of amyloid β-peptide, tau and α-synuclein occur in brain regions involved in the regulation of sleep in AD and PD patients, and are sufficient to cause sleep disturbances in animal models of these neurodegenerative disorders. Disturbed regulation of sleep often occurs early in the course of AD and PD, and may contribute to the cognitive and motor symptoms. Treatments that target signaling pathways that control sleep have been shown to retard the disease process in animal models of AD and PD, suggesting a potential for such interventions in humans at risk for or in the early stages of these disorders.

Age-related changes in sleep and circadian rhythms: impact on cognitive performance and underlying neuroanatomical networks

Circadian and homeostatic sleep-wake regulatory processes interact in a fine tuned manner to modulate human cognitive performance. Dampening of the circadian alertness signal and attenuated deterioration of psychomotor vigilance in response to elevated sleep pressure with aging change this interaction pattern. As evidenced by neuroimaging studies, both homeostatic sleep pressure and circadian sleep-wake promotion impact on cognition-related cortical and arousal-promoting subcortical brain regions including the thalamus, the anterior hypothalamus, and the brainstem locus coeruleus (LC). However, how age-related changes in circadian and homeostatic processes impact on the cerebral activity subtending waking performance remains largely unexplored. Post-mortem studies point to neuronal degeneration in the SCN and age-related modifications in the arousal-promoting LC. Alongside, cortical frontal brain areas are particularly susceptible both to aging and misalignment between circadian and homeostatic processes. In this perspective, we summarize and discuss here the potential neuroanatomical networks underlying age-related changes in circadian and homeostatic modulation of waking performance, ranging from basic arousal to higher order cognitive behaviors.

Entrainment of breast (cancer) epithelial cells detects distinct circadian oscillation patterns for clock and hormone receptor genes

Most physiological and biological processes are regulated by endogenous circadian rhythms under the control of both a master clock, which acts systemically and individual cellular clocks, which act at the single cell level. The cellular clock is based on a network of core clock genes, which drive the circadian expression of non-clock genes involved in many cellular processes. Circadian deregulation of gene expression has emerged to be as important as deregulation of estrogen signaling in breast tumorigenesis. Whether there is a mutual deregulation of circadian and hormone signaling is the question that we address in this study. Here we show that, upon entrainment by serum shock, cultured human mammary epithelial cells maintain an inner circadian oscillator, with key clock genes oscillating in a circadian fashion. In the same cells, the expression of the estrogen receptor α (ER A) gene also oscillates in a circadian fashion. In contrast, ER A-positive and -negative breast cancer epithelial cells show disruption of the inner clock. Further, ER A-positive breast cancer cells do not display circadian oscillation of ER A expression. Our findings suggest that estrogen signaling could be affected not only in ER A-negative breast cancer, but also in ER A-positive breast cancer due to lack of circadian availability of ER A. Entrainment of the inner clock of breast epithelial cells, by taking into consideration the biological time component, provides a novel tool to test mechanistically whether defective circadian mechanisms can affect hormone signaling relevant to breast cancer.