Chronobiological Approach Research Articles

Ambulatory Blood Pressure Monitoring and Circadian Rhythm of Blood Pressure in Diabetes Mellitus

Systolic and diastolic blood pressures display a circadian rhythmicity that can be assessed by 24-hour ambulatory blood pressure monitoring and analysed using the cosinor procedure. Altered characteristics to the circadian rhythm of blood pressure, which may result in adverse health outcomes, have been observed in both prediabetes and diabetes. We have investigated the circadian variability of blood pressure in patients with type 1 and type 2 diabetes. Chronobiologically interpreted ambulatory blood pressure monitoring uncovered not only midline estimating statistic of rhythm (MESOR)-hypertension and circadian hyper-amplitude-tension, but also circadian ecphasia (an odd timing of the daily blood pressure swing). Diastolic blood pressure acrophases were found to be phase shifted to earlier along the time axis only in patients with diabetes, but not in those with essential hypertension. Several mechanisms, from changes in nutrient-dependent signalling pathways to diabetic autonomic neuropathy, can contribute to alterations of circadian time structures in diabetic people. The chronology of blood pressure changes in animal models of diabetes and hypertension suggests that a chronobiological approach to the diagnosis of blood pressure disorders could offer advantages, but longitudinal studies in humans are needed to determine its potential relevance in hypertension associated with diabetes.

Infradian Modulation of Circadian Rhythms of Proliferative Activity of the Esophageal and Corneal Epithelium

Many-day rhythms of proliferative activity of the corneal and esophageal epithelium and serum corticosterone levels were studied in adult male Wistar rats. We detected a 4-day rhythm of proliferative activity of esophageal epithelium negatively correlating with corticosterone level. A more pronounced decrease in the number of mitoses in the esophageal and corneal epithelium was recorded every 12 days. Analysis of the rhythm of mitotic activity in different experimental series carried out over 9 months showed that the acrophase of the detected 4- and 12-day periods is shifted 1 day forward every 69-73 days. The detected infradian constituents of the circadian rhythms of epithelial proliferative activity should be taken into consideration in experimental studies and in development of chronobiological approaches to the treatment of diseases caused by disorders of the proliferative activity of the epithelium.

Re-examining "Temporal Niche"

The circadian system temporally organizes physiology and behavior throughout the 24-h day. At the core of this organization lies a network of multiple circadian oscillators located within the central nervous system as well as in virtually every peripheral organ. These oscillators define a 24-h temporal landscape of mutually interacting circadian rhythms that is known as the temporal niche of a species. This temporal niche is constituted by the collective phases of all biological rhythms emerging from this multi-oscillatory system. We review evidence showing that under different environmental conditions, this system can adopt different harmonic configurations. Thus, the classic chronobiological approach of searching for "the" circadian phase of an animal-typically by studying circadian rhythms of locomotor activity-represents a narrow look into the circadian system of an animal. We propose that the study of hormonal rhythms may lead to a more insightful assessment of a species' temporal niche.

The chronorhythmical changes of the functional activity of the kidneys in pathology

At the present moment a study of a combined action of different pathogenic factors, in particular, the effects of metal salts under the conditions of the stress action remains topical. Hence, at the present stage of the development of medicine a chronobiological approach towards developing methods of prophylaxis and correction of the consequences of influensing on the organism of different damaging factors of the environment assumes an especially topical significance. The chronostructure of rhythms of many physiological processes in man is an important criterion of diagnostics and treatment efficiency.

A new chronobiological approach to discriminate between acute and chronic depression using peripheral temperature, rest-activity, and light exposure parameters

BackgroundCircadian theories for major depressive disorder have suggested that the rhythm of the circadian pacemaker is misaligned. Stable phase relationships between internal rhythms, such as temperature and rest/activity, and the external day-night cycle, are considered to be crucial for adapting to life in the external environmental. Therefore, the relationship and possible alterations among (i) light exposure, (ii) activity rhythm, and (iii) temperature rhythm could be important factors in clinical depression. This study aimed to investigate the rhythmic alterations in depression and evaluate the ability of chronobiological parameters to discriminate between healthy subjects and depressed patients.MethodsThirty female subjects, including healthy subjects, depressed patients in the first episode, and major recurrent depression patients. Symptoms were assessed using Hamilton Depression Scale, Beck Depression Inventory and Montgomery-Äsberg Scale. Motor activity, temperature, and light values were determined for 7 days by actigraph, and circadian rhythms were calculated.ResultsDepressed groups showed a lower amplitude in the circadian rhythm of activity and light exposure, but a higher amplitude in the rhythm of peripheral temperature. The correlation between temperature and activity values was different in the day and night among the control and depressed groups. For the same level of activity, depressed patients had lowest temperature values during the day. The amplitudes of temperature and activity were the highest discriminant parameters.ConclusionsThese results indicate that the study of rhythms is useful for diagnosis and therapy for depressive mood disorders.

Diel rhythms in shallow Mediterranean rocky-reef fishes: a chronobiological approach with the help of trained volunteers

Behavioural rhythms in marine species have been mostly investigated in laboratory organisms and their expression within the animals' natural environments remains largely unknown. Here, we studied diel (i.e. 24-hours-based) and intra-diel (i.e. 12-hours-based) rhythmic variations in the abundance of seven shallow rocky-reef fish species, namelyCoris julis, Epinephelus marginatus, Sarpa salpa, Serranus cabrilla, Serranus scriba, Sparisoma cretenseandThalassoma pavo, along the rocky shores of Linosa Island (Mediterranean Sea). Data were visually collected by trained volunteers along fixed transects at 3-hourly intervals throughout six consecutive 24-hours periods. Density estimates can vary greatly between consecutive days and during 24-hours periods according not only to the major day–night changeover but also to minor intra-diel variations at the daylight hours. In the case ofT. pavo, C. julis, S. cabrillaand S. salpa waveform analyses showed midday troughs in abundance within the 24-hours period but significant variation within the hours of daylight was highlighted only forT. pavo. Although results were not conclusive at the intra-dial level, the employment of volunteers represented a valuable tool for chronobiology, suitable to improve our understanding of fish behaviour in natural systems.

Chronobiological approach in the study of daily dynamics of cerebral blood flow in teenagers with consequence of natal trauma of cervical spine

Variations of cerebral blood flow have been studied during a day with the use of rheoencephalography and Voll diagnostics in healthy teenagers and teenagers with consequences of natal trauma of cervical spine. The studies have proved that teenagers with trauma consequences had amplitude and phase desynchronosis in all REG parameters and electrical conductivity of some points of Voll meridians. The determination of the time, at which extreme REG values (acrophase and bathyphase) take place, with the aid of cosinor-analysis forms the basis for more correct scheduling of procedures during a day for teenagers with consequences of natal trauma of cervical spine.

Possibilities of group chronophysiotherapy at gall-bladder dyskinesias

The aim was to study the efficiency of group chronophysiotherapy of patients with motor defects of gall bladder living in the West-Siberian region. The analysis of the obtained results indicates that the combined physiotherapy of patients with gall-bladder dyskinesias with the use of the group chronobiological approach favors the improvement of the functional status of the biliary excretion system with normalization of indices of the contractile function of gall bladder and the increase of organism adaptability without their stress.

A chronobiological approach to addiction

Recent chronobiological studies show that drug consumption has a negative effect on circadian rhythmic expression. Circadian rhythm may even disappear in extreme cases, which suggests a lesser quality of the wake and sleep periods. Moreover, some circadian genes (Clock, Period) may be involved as biological risk factors in drug addictions. At the same time, the modification of their genetic expression has been found in patients with addiction disorders. Evening circadian typology is currently being considered as a risk factor in the onset and maintenance of drug consumption, while the morning typology appears to be a protection factor. The circadian genes are also related to psychopathologies such as mood disorders, and in the future, their implication in dual pathology should be further studied. Preventive and therapeutic approaches to addiction should take into account circadian rhythmic organization. In many cases, it may suffice to establish regular time patterns of wake–sleep, meals and daily activity with a tendency towards a morningness pattern of functioning. Other strategies, such as light therapy and melatonin administration, may be applied for long periods of time, since they have shown an excellent degree of security, and may also be a protective measure against relapse or the appearance of neuropsychiatric symptoms.Part of this work was presented at the 13th International Symposium on Substance Abuse Treatment (23–25 March, Barcelona, Spain).

Chronobiological Approaches to Alzheimers Disease

Dynamic circadian rhythms contribute to memory formation, and the hormonal and neurochemical changes that follow circadian patterns are frequently dysregulated with aging. The effect of aging on circadian rhythms is a double-edged sword; on one hand, poor sleep quality compromises neuronal structure and function in regions that support cognition, and on the other hand, perturbation of central and peripheral oscillators changes the hormonal milieu, with consequences for neuroplasticity. In the current review, recent developments surrounding the circadian regulation of memory formation are described, with reference to how mechanisms that support temporal coding might change with advancing age. The cognitive consequences of changes in sleep patterns are also discussed. New roles for the circadian clock genes period-1, period-2, and bmal1 in memory formation are discussed in the context of age-related cognitive decline. The potential for chronobiological approaches to the treatment and prevention of Alzheimer's disease merits further exploration from a pharmacotherapeutic perspective, as the timing of drug delivery could potentiate or diminish treatment efficacy.

TIME DEPENDENT THERAPY BASED ON CHRONOPHARMACOLOGY

Chronopharmacology is useful to solve problems of drug optimization, i.e. to enhance the desired efficiency or to reduce its undesired effects. In the human organism (among other animal species) the metabolic fate of a pharmacologic agent (as well as that of a nutrient) is not constant as a function of time. Thus, the chronobiologic approach of pharmacologic phenomena involves a lesser risk of errors and/or false information than the conventional homeostatic approach. This review focuses on chronopharmacotherapy of various diseases related to different human body systems, and also provides a molecular biological explanation for the influence of medications on the clock genes. Biological rhythms not only impact the pathophysiology of diseases, but the pharmacokinetics and pharmacodynamics of medications. Chronopharmacotherapy is the investigative science that elucidates the biological rhythm dependencies of medications

MRNA expression in osteoclasts: a chronobiological approach

The objective of the present study was to investigate chronobiological rhythms of H+-ATPase and carbonic anhydrase II mRNA expression in rat osteoclasts. Rat osteoclasts were obtained through anatomical dissociation technique from bones. Experimental groups included 3 h, 6 h, 12 h, 24 h and 48 h cell cultures. mRNA expression of Atp6a1 and Atp6i of H+-ATPase and carbonic anhydrase II in osteoclasts were detected via fluorescent probe q-PCR. The data were analyzed using ANOVA with SPSS 12.0. mRNA expression of H+-ATPase and carbonic anhydrase II increased when the cell culture time was prolonged, and reached a peak value at 24 h; however later cultures resulted in a significant decrease in mRNA expression. Furthermore, mRNA expression of H+-ATPase and carbonic anhydrase II in osteoclasts varied with time of culture.

Hypobaric Impact on Clinical Tolerance and 24-h Patterns in Iron Metabolism Markers and Plasma Proteins in Men

Long-distance flights can cause a number of clinical problems due to mild hypoxia resulting from cabin pressurization. Using a chronobiological approach, the aim of this work was to assess the clinical tolerance and biological impact of daytime exposure to hypobaric hypoxia on markers of iron metabolism and plasma proteins. Fourteen healthy, male volunteers, ages 23 to 39 yrs, spent 8.5 h in a hypobaric chamber (from 07:45 to 16:15 h) simulating an altitude of 8000 ft. This was followed by another 8.5-h session 4 wks later simulating conditions at an altitude of 12,000 ft. Biological variables were assayed every 2 h over two 24-h spans (control and hypoxia spans, respectively) per simulated altitude. Whereas most of the subjects tolerated the 8000 ft exposure well, eight subjects (57%) presented clear clinical signs of hypoxic intolerance at 12,000 ft. The 24-h blood iron profile showed a biphasic pattern at both altitude simulations, with a significant (∼40%) increase during hypoxia, followed by a (∼25%) decrease during the first hours of recovery. The iron circadian rhythm showed a significant phase delay during the hypoxic exposure at 8000 ft vs. reference. Mean 24-h ferritin levels decreased at both altitudes, but mainly during the nighttime after the 12,000 ft exposure in accordance with Cosinor analysis. The transferrin and total plasma proteins 24-h profiles did not show significant change. Moreover, significant differences, mainly in iron, ferritin, and transferrin, were found at 12,000 ft according to the clinical tolerance to hypoxia, and significant correlations were found between the mid-range crossing times, i.e., here half-descent times (d-T50), for ferritin and total plasma proteins and the reported level of clinical discomfort under hypoxia. This study shows that an 8.5-h exposure to mild hypoxia is able to alter very quickly the 24-h pattern of iron and ferritin. These alterations seem to depend, at least in part, on the clinical tolerance to hypoxia and may help explain the interindividual differences observed in the tolerance to hypoxia. (Author correspondence: yvan.touitou@chronobiology.fr)

Activity rhythms in the deep-sea: a chronobiological approach

Ocean waters deeper than 200 m cover 70% of the Earth's surface. Light intensity gets progressively weaker with increasing depth and internal tides or inertial currents may be the only remaining zeitgebers regulating biorhythms in deep-sea decapods. Benthopelagic coupling, exemplified by vertically moving shrimps within the water column, may also act as a source of indirect synchronisation to the day-night cycle for species living in permanently dark areas. At the same time, seasonal rhythms in growth and reproduction may be an exogenous response to spring-summer changes in upper layer productivity (via phytoplankton) or, alternatively, may be provoked by the synchronisation mediated by an endogenous controlling mechanism (via melatonin). In our review, we will focus on the behavioural rhythms of crustacean decapods inhabiting depths where the sun light is absent. Potential scenarios for future research on deep-sea decapod behaviour are suggested by new in situ observation technologies. Permanent video observatories are, to date, one of the most important tools for marine chronobiology in terms of species recognition and animals' movement tracking.

Chronomics of climatic variations of tree ring width

Variations in the average annual tree rings of 11 sequoia trees for 2189 years are studied. The power spectrum of tree ring variations, calculated by the Maximum Entropy Method (MEM), is power-law in character with the coefficient β close to −1.00, suggesting the fractal character of the considered time series. The calculations of the coefficient β in a 200-year sliding window showed that this coefficient rapidly drops to zero or very small positive values, indicating a break in the fractal structure in some intervals. We identified seven such episodes, two (the latest) of which correspond to Sporer and Maunder solar minima. The other five episodes, which occurred around 100 BC and 500, 700, 820, and 880 AD, i.e., before regular sunspot observations, may also correspond to climate changes. By combining methods aimed at identifying the specific spectral components, such as the Schwabe cycle and behavior of the 1/f dependence as a chaos characteristic, the chronobiologic (chronomics) approach can be used to study the global climatic processes—such as cycles of about 500 years—bearing on global warming.

A chronobiological approach to the treatment of obesity in children based at a sanatorium and spa facility

The objective of the study was to evaluate results of non-medicamental treatment of 167 children with obesity taking into account dynamics of annual rhythms of their clinical, hormonal, metabolic, and psychological characteristics. The period from August till November was shown to be especially favourable in terms of body weight loss, improvement of hormonal, metabolic, and psychic status. Analysis of these changes permitted to correct the proposed mode of combined therapy of obesity during the period from December till July.

Heritable circadian period length in a wild bird population.

Timing is essential, but circadian clocks, which play a crucial role in timekeeping, are almost unaddressed in evolutionary ecology. A key property of circadian clocks is their free-running period length (τ), i.e. the time taken for a full cycle under constant conditions. Under laboratory conditions, concordance of τ with the ambient light-dark cycle confers major fitness benefits, but little is known about period length and its implications in natural populations. We therefore studied natural variation of circadian traits in a songbird, the great tit (Parus major), by recording locomotor activity of 98 hand-raised, wild-derived individuals. We found, unexpectedly, that the free-running period of this diurnal species was significantly shorter than 24 h in constant dim light. We furthermore demonstrate, to our knowledge for the first time in a wild vertebrate, ample genetic variation and high heritability (h(2) = 0.86 ± 0.24), implying that period length is potentially malleable by micro-evolutionary change. The observed, short period length may be a consequence of sexual selection, as offspring from extra-pair matings had significantly shorter free-running periods than their half-siblings from within-pair matings. These findings position circadian clocks in the 'real world' and underscore the value of using chronobiological approaches in evolutionary ecology. Evolutionary ecologists study variation and its fitness consequences, but often have difficulties relating behavioural variation to physiological mechanisms. The findings presented here open the possibility that properties of internal, circadian clocks affect performance in traits that are relevant to fitness and sexual selection.

YРА therapy by a background resonance radiation in chronorehabilitation of patients with chronic cholecystitis in combination with chronic opisthorchosis

The chronobiological approach was used to improve indices of functional activity of the biliary excretion system and enhance the general efficiency of treatment at chronic cholecystitis in combination with chronic opistorhcosis. For this purpose, transverse galvanization of the eigatric area was carried out against the background of general health-improving procedures and the YРА therapy by the background resonance radiator after intake of herbal remedy (hepatosol). The treatment was carried out with allowance for the individual phase of the rhythm of activity of the biliary excretion system or with the use of a group approach with procedures prescribed in the rising (from 10:00 to 11:00) or declining (from 13:00 to 14.00) phase of the rhythm. The results obtained indicated that the chronophysiotherapy in patients chronic cholecystitis in combination with chronic opistorhcosis increase the efficiency of treatment, while the accessibility of this approach confirms its practical significance.

Do Restless Legs Syndrome (RLS) and Periodic Limb Movements of Sleep (PLMS) Play a Role in Nocturnal Hypertension and Increased Cardiovascular Risk of Renally Impaired Patients?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease. (Author correspondence: prf@unife.it)

DO RESTLESS LEGS SYNDROME (RLS) AND PERIODIC LIMB MOVEMENTS OF SLEEP (PLMS) PLAY A ROLE IN NOCTURNAL HYPERTENSION AND INCREASED CARDIOVASCULAR RISK OF RENALLY IMPAIRED PATIENTS?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease. (Author correspondence: prf@unife.it)