Cancer and rhythm

Relationship Between Diurnal Cortisol Profile and Sleep Quality in Patients With Hepatocellular Carcinoma

Purpose:

Hepatocellular carcinoma (HCC) is the second leading cause of cancer mortality worldwide. Sleep problems are common in HCC patients and may be attributable to disturbances in the circadian rhythm. Research into the role of circadian rhythms in sleep quality among HCC patients is lacking, however. This study investigated the relationship between the diurnal cortisol profile and sleep quality among HCC patients. We aimed to identify alterations in the diurnal cortisol profile in patients with HCC compared to healthy controls and investigate whether they were associated with poor sleep quality among HCC patients.

Methods:

Participants comprised 75 HCC patients and 33 healthy individuals. The Taiwanese version of the Pittsburgh Sleep Quality Index (PSQI-T) was administered to assess sleep quality. Saliva samples were collected on 3 consecutive days at five time points daily to measure diurnal cortisol levels.

Results:

In the HCC group, 89.3% of individuals were poor sleepers (PSQI-T > 5), whereas among healthy individuals, 30.3% were poor sleepers. While the healthy participants’ diurnal cortisol profile followed a typical pattern that peaked 30 min after waking and declined gradually throughout the day, the cortisol level in the HCC patients rebounded at bedtime. Higher cortisol levels were marginally correlated with poor sleep quality ( OR = 1.00007, p < .05).

Conclusions:

Our study suggests a potential association between disturbed circadian rhythm and poor sleep quality in HCC patients. Further investigation of the causal relationship between sleep and circadian rhythm is warranted.

Dynamics of Vagal Activity Due to Surgery and Subsequent Rehabilitation

Background

Vagal activity is critical for maintaining key body functions, including the stability of inflammatory control. Its weakening, such as in the aftermatch of a surgery, leaves the body vulnerable to diverse inflammatory conditions, including sepsis.

Methods

Vagal activity can be measured by the cardiorespiratory interaction known as respiratory sinus arrhythmia or high-frequency heart-rate variability (HRV). We examined the vagal dynamics before, during and after an orthopedic surgery. 39 patients had their HRV measured around the period of operation and during subsequent rehabilitation. Measurements were done during 24 h circadian cycles on ten specific days. For each patient, the circadian vagal activity was calculated from HRV data.

Results

Our results confirm the deteriorating effect of surgery on vagal activity. Patients with stronger pre-operative vagal activity suffer greater vagal withdrawal during the peri-operative phase, but benefit from stronger improvements during post-operative period, especially during the night. Rehabilitation seems not only to efficiently restore the vagal activity to pre-operative level, but in some cases to actually improve it.

Discussion

Our findings indicate that orthopedic rehabilitation has the potential to strengthen the vagal activity and hence boost inflammatory control. We conclude that providing a patient with a vagal reinforcement procedure prior to the surgery (“pre-habilitation”) might be a beneficial strategy against post-operative complications. The study also shows the clinical usefulness of quantifying the cardiorespiratory interactions.

Chronotherapeutics: Recognizing the Importance of Timing Factors in the Treatment of Disease and Sleep Disorders

This review describes the characteristics of a number of pathologies, which are considered from the point of view of chronobiology, that is, the way in which biological processes are expressed throughout the 24-hour day. This perspective is a relatively new way of thinking about disease and additionally about how to treat diseases. It has called attention to the importance of not only the quantity of a drug that is administered but also when it is administered. In addition, the review presents an overview of the emerging clinical strategies known as chronotherapeutics, that is, the effects of the daily scheduling of drug administration and the consequences of the activity and efficacy of therapies that are applied in this manner. This article also reviews innovative ways in which physicians are applying time-specified drug treatment (chronopharmacology) for sleep disorders. Here, we present a systematic description of chronopharmacology as well as definitions of key terms that, we believe, will be helpful for newcomers to the field. It is hoped that greater awareness of this new perspective on pharmacology will promote its adoption by researchers and clinicians.

Circadian protein BMAL1 promotes breast cancer cell invasion and metastasis by up-regulating matrix metalloproteinase9 expression

Background

Metastasis is an important factor in the poor prognosis of breast cancer. As an important core clock protein, brain and muscle arnt-like 1 (BMAL1) is closely related to tumorigenesis. However, the molecular mechanisms that mediate the role of BMAL1 in invasion and metastasis remain largely unknown. In this study, we investigated the BMAL1 may take a crucial effect in the progression of breast cancer cells.

Methods

BMAL1 and MMP9 expression was measured in breast cell lines. Transwell and scratch wound-healing assays were used to detect the movement of cells and MTT assays and clonal formation assays were used to assess cells’ proliferation. The effects of BMAL1 on the MMP9/NF-κB pathway were examined by western blotting, co-immunoprecipitation and mammalian two-hybrid.

Results

In our study, it showed that cell migration and invasion were significantly enhanced when overexpressed BMAL1. Functionally, overexpression BMAL1 significantly increased the mRNA and protein level of matrix metalloproteinase9 (MMP9) and improved the activity of MMP9. Moreover, BMAL1 activated the NF-κB signaling pathway by increasing the phosphorylation of IκB and promoted human MMP9 promoter activity by interacting with NF-kB p65, leading to increased expression of MMP9. When overexpressed BMAL1, CBP (CREB binding protein) was recruited to enhance the activity of p65 and further activate the NF-κB signaling pathway to regulate the expression of its downstream target genes, including MMP9, TNFα, uPA and IL8, and then promote the invasion and metastasis of breast cancer cells.

Conclusions

This study confirmed a new mechanism by which BMAL1 up-regulated MMP9 expression to increase breast cancer metastasis, to provide research support for the prevention and treatment of breast cancer.

Sleep Disorders are a Prevalent and Serious Comorbidity in Dry Eye

Purpose

Sleep is an essential life habit and closely associated with lifespan, diabetes, hypertension, and mental health. Sleep disorders are a prominent, but overlooked problem in patients with dry eye disease (DED), characterized by a poor sleep index, short sleep duration, long sleep latency, and poor subjective sleep. DED and sleep disorders are more prevalent in women than men. Moreover, sleep quality in DED is worse than in other eye diseases, including glaucoma, retinal diseases, cataract, and allergic and chronic conjunctivitis.

Methods

We reviewed the literature for studies investigating sleep and health, eyes and sleep, and DED and sleep, in terms of systemic and eye health, especially in women.

Results

Two studies reported that approximately half of patients with DED suffer from poor sleep. The severity of mood disorders, including anxiety and depression, is correlated strongly with sleep disorders in DED, and the symptoms and signs of DED, especially pain, also are correlated with sleep quality. Sleep disorders are documented in primary Sjögren's syndrome and an association with sleep apnea and depression is suggested. Primary Sjögren's syndrome includes arthritis and other rheumatic disease causing pain and fatigue; however, how sicca contributes to sleep disorders is not known.

Conclusions

Possible explanations for sleep disorders in DED may be depression, pain, and eye exposure at night. Reciprocal effects may be expected and consultation-liaison psychiatry is recommended for the management of sleep disorders in DED. Topical medication and lid heating also may be advantageous for sleep quality in DED.

Effect of Daily Light on c-Fos Expression in the Suprachiasmatic Nucleus under Jet Lag Conditions

Jet-lag symptoms arise from temporal misalignment between the internal circadian clock and external solar time when traveling across multiple time zones. Light is known as a strong timing cue of the circadian clock. We here examined the effect of daily light on the process of jet lag by detecting c-Fos expression in the master clock neurons in the suprachiasmatic nucleus (SCN) under 8-hr phase-advanced jet lag condition. In WT mice, c-Fos-immunoreactivity was found at 1–2 hours on the first day after light/dark (LD) phase-advance. This induction was also observed on the second and third days, although their levels were diminished day by day. In contrast, c-Fos induction in the SCN of V1a^–/–V1b^–/– mice, which show virtually no jet lag symptoms even after 8-hr phase-advance, was only detected on the first day. These results indicate that external light has affected SCN neuronal activity for 3 days after LD phase-advance in WT mice suggesting the continuous progress of activity change of SCN neurons under jet lag conditions. Noteworthy, limited c-Fos induction in V1a^–/–V1b^–/– SCN is also consistent with the rapid reentrainment of the SCN clock in mutant mice after 8-hr LD phase-advance.

Circadian locomotor output cycles kaput affects the proliferation and migration of breast cancer cells by regulating the expression of E-cadherin via IQ motif containing GTPase activating protein 1

The circadian rhythm regulates numerous physiological activities, including sleep and wakefulness, behavior, immunity and metabolism. Previous studies have demonstrated that circadian rhythm disorder is associated with the occurrence of tumors. Responsible for regulating a number of functions, the Circadian locomotor output cycles kaput (Clock) gene is one of the core regulatory genes of circadian rhythm. The Clock gene has also been implicated in the occurrence and development of tumors in previously studies. The present study evaluated the role of the Clock gene in the proliferation and migration of mouse breast cancer 4T1 cells, and investigated its possible regulatory pathways and mechanisms. It was reported that downregulation of Clock facilitated the proliferation and migration of breast cancer cells. Further investigation revealed the involvement of IQ motif containing GTPase activating protein 1 (IQGAP1) protein expression in the Clock regulatory pathway, further influencing the expression of E-cadherin, a known proprietor of tumor cell migration and invasion. To the best of our knowledge, the present study is the first to report that Clock, acting through the regulation of the scaffolding protein IQGAP1, regulates the downstream expression of E-cadherin, thereby affecting tumor cell structure and motility. These results confirmed the role of Clock in breast cancer tumor etiology and provide insight regarding the molecular avenues of its regulatory nature, which may translate beyond breast cancer into other known functions of the gene.

Impact of a combined multimodal-aerobic and multimodal intervention compared to standard aerobic treatment in breast cancer survivors with chronic cancer-related fatigue - results of a three-armed pragmatic trial in a comprehensive cohort design

BACKGROUND

Cancer-related fatigue (CRF) and insomnia are major complaints in breast cancer survivors (BC). Aerobic training (AT), the standard therapy for CRF in BC, shows only minor to moderate treatment effects. Other evidence-based treatments include cognitive behavioral therapy, e.g., sleep education/restriction (SE) and mindfulness-based therapies. We investigated the effectiveness of a 10-week multimodal program (MT) consisting of SE, psycho-education, eurythmy- and painting-therapy, administered separately or in combination with AT (CT) and compared both arms to AT alone.

METHODS

In a pragmatic comprehensive cohort study BC with chronic CRF were allocated randomly or by patient preference to (a) MT, (b) CT (MT + AT) or (c) AT alone. Primary endpoint was a composite score of the Pittsburgh Sleep Quality Index and the Cancer Fatigue Scale after 10 weeks of intervention (T1); a second endpoint was a follow-up assessment 6 months later (T2). The primary hypothesis stated superiority of CT and non-inferiority of MT vs. AT at T1. A closed testing procedure preserved the global α-level. The intention-to-treat analysis included propensity scores for the mode of allocation and for the preferred treatment, respectively.

RESULTS

Altogether 126 BC were recruited: 65 were randomized and 61 allocated by preference; 105 started the intervention. Socio-demographic parameters were generally balanced at baseline. Non-inferiority of MT to AT at T1 was confirmed (p < 0.05), yet the confirmative analysis stopped as it was not possible to confirm superiority of CT vs. AT (p = 0.119). In consecutive exploratory analyses MT and CT were superior to AT at T1 and T2 (MT) or T2 alone (CT), respectively.

CONCLUSIONS

The multimodal CRF-therapy was found to be confirmatively non-inferior to standard therapy and even yielded exploratively sustained superiority. A randomized controlled trial including a larger sample size and a longer follow-up to evaluate multimodal CRF-therapy is highly warranted.

TRIAL REGISTER

DRKS-ID: DRKS00003736 . Recruitment period June 2011 to March 2013. Date of registering 19 June 2012.

The significance of circadian rhythms and dysrhythmias in critical illness

Many physiological and cellular processes cycle with time, with the period between one peak and the next being roughly equal to 24 h. These circadian rhythms underlie 'permissive homeostasis', whereby anticipation of periods of increased energy demand or stress may enhance the function of individual cells, organ systems or whole organisms. Many physiological variables related to survival during critical illness have a circadian rhythm, including the sleep/wake cycle, haemodynamic and respiratory indices, immunity and coagulation, but their clinical significance remains underappreciated. Critically ill patients suffer from circadian dysrhythmia, manifesting overtly as sleep disturbance and delirium, but with widespread covert effects on cellular and organ function. Environmental and pharmacological strategies that ameliorate or prevent circadian dysrhythmia have demonstrated clinical benefit. Harnessing these important biological phenomena to match metabolic supply to demand and bolster cell defenses at the apposite time may be a future therapeutic strategy in the intensive care unit.

Clock genes and salt-sensitive hypertension: a new type of aldosterone-synthesizing enzyme controlled by the circadian clock and angiotensin II

With the current societal norm of shiftwork and long working hours, maintaining a stable daily life is becoming very difficult. An irregular lifestyle disrupts circadian rhythms, resulting in the malfunction of body physiology and ultimately leading to lifestyle-related diseases, including hypertension. By analyzing completely arrhythmic Cry1/Cry2 double-knockout (Cry-null) mice, we found salt-sensitive hypertension accompanied by hyperaldosteronism. On the basis of a DNA microarray analysis of the adrenal gland and subsequent biochemical analyses, we discovered that Hsd3b6/HSD3B1, a subtype of 3β-HSD, is markedly overexpressed in aldosterone-producing cells in the Cry-null adrenal cortex. In addition, we found that Hsd3b6/HSD3B1, which converts pregnenolone to progesterone, is a clock-controlled gene and might also be a key enzyme for the regulation of aldosterone biosynthesis, in addition to the previously established CYP11B2, which synthesizes aldosterone from deoxycorticosterone. Importantly, angiotensin II induces HSD3B1 via the transcription factor NGFIB in human adrenocortical H295R cells, similarly to CYP11B2. As HSD3B1 levels are abnormally high in the adrenal aldosterone-producing cells of idiopathic hyperaldosteronism (IHA), the temporal component of this system in the pathophysiology of IHA is a promising area for future research.

Effect of arousing stimuli on circulating corticosterone and the circadian rhythms of luteinizing hormone (LH) surges and locomotor activity in estradiol-treated ovariectomized (ovx+EB) Syrian hamsters

In most proestrous hamsters, novel wheel exposure phase advances activity rhythms and blocks the preovulatory LH surge, which occurs 2h earlier the next day. Because wheel immobilization does not prevent these effects we hypothesized that arousal alone blocks and phase advances the LH surge. Ovariectomized (ovx) hamsters received a jugular vein cannula and estradiol benzoate (EB) or vehicle was injected sc. The next day (Day 1), at zeitgeber time (ZT) 4-5 (ZT 12 = lights off), after obtaining a blood sample, each hamster was exposed to constant darkness (DD), and either remained in her home cage or was transferred to a new cage and exposed to a running wheel or a 2-hour arousal paradigm. Blood samples were obtained in dim red light and activity was recorded hourly until ~ZT 10-11 on Days 1 and 2. For the next 1-2 weeks, activity was monitored in DD. Plasma LH and corticosterone were assessed by RIA. Novel wheel exposure or arousal at ZT 4 greatly attenuated the Day 1 LH surge in ovx+EB hamsters, and phase advanced the Day 2 LH surge by about 2h. In proestrous hamsters, novel wheel exposure led to a prolonged (>2h) increase in corticosterone levels only when LH surges were blocked. Phase advances in activity rhythms were enhanced by estradiol and arousal. The results suggest that estradiol modulates the effectiveness of non-photic stimuli. The role of the increased activity of the hypothalamic-pituitary-adrenal axis associated with novel wheel-induced attenuation of LH surges in ovx+EB hamsters remains to be determined.

'Chronomics' in ICU: circadian aspects of immune response and therapeutic perspectives in the critically ill

Complex interrelations exist between the master central clock, located in the suprachiasmatic nuclei of the hypothalamus, and several peripheral clocks, such as those found in different immune cells of the body. Moreover, external factors that are called ‘timekeepers’, such as light/dark and sleep/wake cycles, interact with internal clocks by synchronizing their different oscillation phases. Chronobiology is the science that studies biologic rhythms exhibiting recurrent cyclic behavior. Circadian rhythms have a duration of approximately 24 h and can be assessed through chronobiologic analysis of time series of melatonin, cortisol, and temperature. Critically ill patients experience severe circadian deregulation due to not only the lack of effective timekeepers in the intensive care unit (ICU) environment but also systemic inflammation. The latter has been found in both animal and human studies to disrupt circadian rhythmicity of all measured biomarkers. The aims of this article are to describe circadian physiology during acute stress and to discuss the effects of ICU milieu upon circadian rhythms, in order to emphasize the value of considering circadian-immune disturbance as a potential tool for personalized treatment. Thus, besides neoplastic processes, critical illness could be linked to what has been referred as ‘chronomics’: timing and rhythm. In addition, different therapeutic perspectives will be presented in association with environmental approaches that could restore circadian connection and hasten physical recovery.

Circadian disruption and remedial interventions: effects and interventions for jet lag for athletic peak performance

Jet lag has potentially serious deleterious effects on performance in athletes following transmeridian travel, where time zones are crossed eastwards or westwards; as such, travel causes specific effects related to desynchronization of the athlete's internal body clock or circadian clock. Athletes are particularly sensitive to the effects of jet lag, as many intrinsic aspects of sporting performance show a circadian rhythm, and optimum competitive results require all aspects of the athlete's mind and body to be working in tandem at their peak efficiency. International competition often requires transmeridian travel, and competition timings cannot be adjusted to suit individual athletes. It is therefore in the interest of the individual athlete and team to understand the effects of jet lag and the potential adaptation strategies that can be adopted. In this review, we describe the underlying genetic and physiological mechanisms controlling the circadian clock and its inherent ability to adapt to external conditions on a daily basis. We then examine the fundamentals of the various adaptation stimuli, such as light, chronobiotics (e.g. melatonin), exercise, and diet and meal timing, with particular emphasis on their suitability as strategies for competing athletes on the international circuit. These stimuli can be artificially manipulated to produce phase shifts in the circadian rhythm to promote adaptation in the optimum direction, but care must be taken to apply them at the correct time and dose, as the effects produced on the circadian rhythm follow a phase-response curve, with pronounced shifts in direction at different times. Light is the strongest realigning stimulus and careful timing of light exposure and avoidance can promote adjustment. Chronobiotics such as melatonin can also be used to realign the circadian clock but, as well as timing and dosage issues, there are also concerns as to its legal status in different countries and with the World Anti-Doping Agency. Experimental data concerning the effects of food intake and exercise timing on jet lag is limited to date in humans, and more research is required before firm guidelines can be stated. All these stimuli can also be used in pre-flight adaptation strategies to promote adjustment in the required direction, and implementation of these is described. In addition, the effects of individual variability at the behavioural and genetic levels are also discussed, along with the current limitations in assessment of these factors, and we then put forward three case studies, as examples of practical applications of these strategies, focusing on adaptations to travel involving competition in the Rugby Sevens World Cup and the 2016 Summer Olympics in Rio de Janeiro, Brazil. Finally, we provide a list of practice points for optimal adaptation of athletes to jet lag.

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.

The Symptom Cluster of Sleep, Fatigue and Depressive Symptoms in Breast Cancer Patients: Severity of the Problem and Treatment Options

Breast cancer is the most commonly diagnosed cancer in women. Insomnia is a significant problem in breast cancer patients, affecting between 20% to 70% of newly diagnosed or recently treated cancer patients. Pain, fatigue, anxiety, and depression are also common conditions in breast cancer and often co-occur with insomnia in symptom clusters, exacerbating one another, and decreasing quality of life (QOL). There have been no clinical trials of drugs for sleep in cancer. Cognitive behavioral psychotherapies on the other hand, have shown some of the most positive results in alleviating the distressing symptoms that often accompany the breast cancer experience, but even these studies have not targeted the symptom cluster. Pharmacological as well as non-pharmacological treatments need to be explored. It might be that a combined pharmacological and behavioral treatment is most efficacious. In short, substantially more research is needed to fully understand and treat the symptom cluster of insomnia, fatigue, pain, depression and anxiety in breast cancer.

Shift work, jet lag, and female reproduction

Circadian rhythms and "clock gene" expression are involved in successful reproductive cycles, mating, and pregnancy. Alterations or disruptions of biological rhythms, as commonly occurs in shift work, jet lag, sleep deprivation, or clock gene knock out models, are linked to significant disruptions in reproductive function. These impairments include altered hormonal secretion patterns, reduced conception rates, increased miscarriage rates and an increased risk of breast cancer. Female health may be particularly susceptible to the impact of desynchronizing work schedules as perturbed hormonal rhythms can further influence the expression patterns of clock genes. Estrogen modifies clock gene expression in the uterus, ovaries, and suprachiasmatic nucleus, the site of the primary circadian clock mechanism. Further work investigating clock genes, light exposure, ovarian hormones, and reproductive function will be critical for indentifying how these factors interact to impact health and susceptibility to disease.

Circadian biology: an unexpected invitee to new time zones

Adaptation to changing light conditions is a hallmark of the circadian clock. A new study points to the critical role played by a transcriptional repressor previously implicated in cell differentiation, highlighting unappreciated links between the clock and the control of development and tumorigenesis.

Adaptation of the Herdecke Quality of Life questionnaire towards quality of life of cancer patients

Although instruments for the measurement of quality of life (QoL) do exist for cancer patients, factors like sleepiness or digestion are only marginally addressed. We intended to adapt the Herdecke Quality of Life (HLQ) towards these aspects in a multi-centre cross-sectional validation study. A group of 293 subjects [79% female, age: 55.9 +/- 13.4 years; 146 cancer patients, 28 patients with rheumatic diseases and a healthy control group (n = 119)]. Structural relations between the items were detected by factor and reliability analyses. For external validation, correlations with the hospital anxiety and depression scale (HADS), self-regulation score (SRS) and the Marburger short questionnaire on chronotypology (MQC) were performed, and test-retest reliability was calculated. Factor analysis found three sub-scales: physical abilities (PA) (Cronbach's alpha = 0.90), sleep quality (SQ) (Cronbach's alpha = 0.89) and digestive well-being (DWB) (Cronbach's alpha = 0.80). Sleep quality correlated well with HADS-anxiety (r =-0.52), PA with HADS-depression (r =-0.49). We found moderate correlations of PA and SQ with SRS, while the HLQ scales did not correlate with the MQC. Analysis of test-retest reliability resulted in values of r = 0.757 for PA, r = 0.715 for SQ and r = 0.603 for DWB. The HLQ-cancer suits to measure unique features of cancer-related QoL aspects. In future studies it has to be tested in larger samples of cancer patients.

The roles of melatonin and light in the pathophysiology and treatment of circadian rhythm sleep disorders

Normal circadian rhythms are synchronized to a regular 24 h environmental light-dark cycle, and the suprachiasmatic nucleus and the hormone melatonin have important roles in this process. Desynchronization of circadian rhythms, as occurs in chronobiological disorders, can produce severe disturbances in sleep patterns. According to the International Classification of Sleep Disorders, circadian rhythm sleep disorders (CRSDs) include delayed sleep phase syndrome, advanced sleep phase syndrome, non-24 h sleep-wake disorder, jet lag and shift-work sleep disorder. Disturbances in the circadian phase position of plasma melatonin levels have been documented in all of these disorders. There is compelling evidence to implicate endogenous melatonin as an important mediator in CRSD pathophysiology, although further research involving large numbers of patients will be required to clarify whether the disruption of melatonin secretion is a causal factor in CRSDs. In this Review, we focus on the use of exogenous melatonin and light therapy to treat the disturbed sleep-wake rhythms seen in CRSDs.

24-hour rhythms in oxidative stress during hepatocarcinogenesis in rats: effect of melatonin or alpha-ketoglutarate

To compare the effects of alpha-ketoglutarate (alpha-KG) and melatonin on 24-h rhythmicity of oxidative stress in N-nitrosodiethylamine (NDEA)-injected Wistar male rats, melatonin (5 mg/kg i.p.) or alpha-KG (2 g/kg through an intragastric tube) was given daily for 20 weeks. In blood collected at 6 time points during a 24-h period, serum activity of aspartate transaminase (AST) and alanine transaminase (ALT) and the levels of alpha-fetoprotein (alpha-FP) were measured as markers of liver function. To assess lipid peroxidation and the antioxidant status, plasma levels of thiobarbituric acid reactive substances (TBARS) and of reduced glutathione (GSH) were measured, together with the activity of erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST). NDEA augmented mesor and amplitude of rhythms in AST and ALT activity and plasma alpha-FP levels and mesor values of plasma TBARS, while decreasing mesor values of plasma GSH and erythrocyte SOD, CAT, GPx and GST. Acrophases were delayed by NDEA in all cases except for alpha-FP rhythm, which became phase-advanced. Co-administration of melatonin or alpha-KG partially counteracted the effects of NDEA. Melatonin decreased mesor of plasma TBARS and augmented mesor of SOD activity. The results indicate that melatonin and alpha-KG are effective in protecting from NDEA-induced perturbation of 24-h rhythms in oxidative stress. Melatonin augmented antioxidant defense in rats.

Space-time clustering and seasonality in diagnosing skin cancers in Wallonia (south-east Belgium)

BACKGROUND

In Westernized populations, the number of diagnosed cases of primary cutaneous cancers, particularly malignant melanomas and basal cell carcinomas (BCC), has been previously shown to fluctuate during specific periods of the year.

OBJECTIVE AND METHOD

The aim of the present 6-year study was to explore the seasonality if any in skin cancer detection in Wallonia (south-east Belgium).

RESULTS

For both malignant melanomas and BCC late spring/early summer and mid-autumn were the periods of highest diagnosis prevalence irrespective of gender. The amplitude of this bimodal evolution remained within the range of 2 standard deviations around the monthly means. Similar seasonal variations were also found in non-neoplastic controls consisting of laboratory samplings of onychomycoses and non-infectious onychodystrophies.

CONCLUSION

There is reason to believe that this timing and rhythm is unrelated to any specific cancer chronomics. Rather, the present findings suggest unspecific seasonality in diagnosing skin disorders including malignancies. A variable patient awareness of changing aspects of the skin according to seasons probably represents the major influence of the described space-time clustering of skin cancer diagnosis.

The daily timing of gene expression and physiology in mammals

Mammalian behavior and physiology undergo daily rhythms that are coordinated by an endogenous circadian timing system. This system has a hierarchical structure, in that a master pacemaker, residing in the suprachiasmatic nucleus of the ventral hypothalamus, synchronizes peripheral oscillators in virtually all body cells. While the basic molecular mechanisms generating the daily rhythms are similar in all cells, most clock outputs are cell-specific. This conclusion is based on genome-wide transcriptome profiling studies in several tissues that have revealed hundreds of rhythmically expressed genes. Cyclic gene expression in the various organs governs overt rhythms in behavior and physiology, encompassing sleep-wake cycles, metabolism, xenobiotic detoxification, and cellular proliferation. As a consequence, chronic perturbation of this temporal organization may lead to increased morbidity and reduced lifespan.

Why life oscillates--from a topographical towards a functional chronobiology

Chronobiology has identified a multitude of rhythms within our body as well as within each living cell. Some of these rhythms, such as the circadian and circannual, interact with our environment, while others run on their own, but are often coupled to the circadian or to other body rhythms. Recent evidence shows that these rhythms might be more important for our health than expected: Disturbance of the circadian rhythms by jet lag or shift work not only evokes autonomic disturbances but also increases the incidence of cancer, as shown in this issue of Cancer Causes and Control. The occurrence of rhythms in the organism obviously bears several advantages: (1) It increases organismic stability by calibrating the system's characteristics: Regulation curves in time and space are crucial for controlling physiological long-term stability. To determine its properties continuously the system varies its parameters slightly over several time scales at different frequencies-akin to what our body does, e.g. in heart-rate variability. (2) Tuning and synchronization of rhythms saves energy: It was Huygens who observed that clocks on a wall tend to synchronize their beats. It turned out later that synchronisation is a very common phenomenon observed in bodies' rhythms and can be found, for example, when we relax or sleep. At such times energy consumption is minimal, our body working most efficiently. (3) Temporal compartmentalization allows polar events to occur in the same space unit: there are polarities in the universe of our body, which cannot happen simultaneously. Systole and diastole, inspiration and expiration, work and relaxation, wakefulness and sleep, reductive and oxidative states cannot be performed efficiently at the same time and place. Temporal compartmentalization is probably the most efficient way to mediate between these polarities. Chronobiology and chronomedicine are opening a new and very exciting understanding of our bodies' regulation. The biological time and its oscillations gain more attention and importance as these interrelations are understood.

Why life oscillates--biological rhythms and health

A multitude of biological rhythms have been identified in the whole organism as well as within each living cell. Some of these rhythms reflect adaptations to our environment, while others run on their own. Recent evidence shows that these rhythms and their interaction might be more important not only for recreation but also for our health. Disturbance of the circadian rhythms by jet lag or shift work not only disturbs our metabolic balance but also increases the incidence of cancer. Rhythms in the organism obviously stabilize systemic functions: They increase organismic stability by calibrating the system's characteristics. Regulation curves in time and space are crucial for controlling physiological long-term stability. To be continuously aware of its properties an autopetic system may vary its parameters slightly over several time scales at different frequencies--akin to what our body does, e.g. in heart-rate variability.