About 8-hour variation of circulating human endothelin-1

Interplay of the Circadian Clock and Endothelin System

The peptide hormone endothelin-1 and its receptors are linked to several disease states. Pharmacological inhibition of this pathway has proven beneficial in pulmonary hypertension, yet its potential in other disease states remains to be realized. This review considers an often understudied aspect of endothelin biology, circadian rhythm regulation and how understanding the intersection between endothelin signaling and the circadian clock may be leveraged to realize the potential of endothelin-based therapeutics.

Incremental Growth Lines in Mouse Molar Dentin Represent 8-hr Ultradian Rhythm

Rhythmic incremental growth lines occur in dental hard tissues of vertebrates, and dentinogenesis in rodent incisors is suggested to be controlled by the 24-hr circadian clock. Rodent incisors continue to grow throughout the animal’s life; however, similar to human teeth, rodent molars stop growing after crown formation. This similarity suggests that the mouse molar is an excellent model to understand the molecular mechanisms underlying growth of human teeth. However, not much is known about the rhythmic dentinogenesis in mouse molars. Here, we investigated the incremental growth lines in mouse molar dentin using tetracycline as the growth marker. The incremental growth lines were observed to be generated at approximately 8-hr intervals in wild-type mice housed under 12:12 hr light-dark conditions. Moreover, the 8-hr rhythmic increments persisted in the wild-type and Bmal1^−/− mice housed in constant darkness, where Bmal1^−/− mice become behaviorally arrhythmic. These results revealed that the dentinogenesis in mouse molars underlie the ultradian rhythms with around 8-hr periodicity. Further, the circadian clock does not seem to be involved in this process, providing new insight into the mechanisms involved in the tooth growth.

Target-Mediated Population Pharmacokinetic Modeling of Endothelin Receptor Antagonists

PURPOSE

Bosentan, clazosentan, and tezosentan are three small-molecule endothelin receptor antagonists (ERAs), displacing endothelin-1 (ET-1) from its binding site. A target-mediated drug disposition (TMDD) pharmacokinetic (PK) model described the non-linearity in the PK of bosentan caused by its high receptor binding affinity with time-dependent varying receptor expression or reappearance. The aim of this analysis was to investigate the presence of TMDD for clazosentan and tezosentan and to corroborate the hypothesis of a diurnal receptor synthesis.

METHODS

PK data from healthy subjects after intravenous (i.v.) administration of single ascending doses of bosentan, clazosentan, and tezosentan were analyzed. Frequent blood samples for PK measurements were collected. Population analyses, simulations, and evaluations were performed using a non-linear mixed-effects modeling approach.

RESULTS

Two-compartment TMDD models were successfully developed describing the PK of all three ERAs with different receptor-complex internalization properties. The observed multiple peaks in the concentration-time profiles were captured with cosine functions on the receptor synthesis rate mimicking a diurnal receptor expression or reappearance. The results strongly suggest that TMDD is a class effect of ERAs.

CONCLUSION

The developed TMDD PK models are a next step towards understanding the complex PK of ERAs and further support the hypothesis that TMDD is a class effect of ERAs.

Does the timing of aspirin administration influence its antiplatelet effect - review of literature on chronotherapy

This publication is a summary of the multidirectional effects of aspirin and its role in modern medicine. The history of aspirin, or acetylsalicylic acid (ASA), and its use dates back to ancient times, although the substance in its pure form has been produced and sold since 1899. Initially it was used for its antipyretic, analgesic, and anti-inflammatory effects. Over the years many other benefits associated with the administration of ASA have been revealed. The mechanism of aspirin’s action was discovered thanks to the British pharmacologist and Nobel Prize winner Sir John Vane. Understanding the effects of acetylsalicylic acid, associated with the inhibition of cyclooxygenase and proinflammatory thromboxane A2 and with increased concentration of vasoprotective, antithrombotic prostacyclin, gave rise to the era of using small “cardiac” doses of ASA in cardiovascular diseases. In addition to the well-researched antiplatelet effect, other properties of ASA have been discovered, such as the non-COX-1 dependent improvement of endothelial function or the hypotensive effect after evening administration. According to the currently available knowledge, it is possible to speak of a pleiotropic effect of ASA and its use in the prevention of cardiovascular diseases, taking into account its anti-aggregation effect, circadian rhythms, and the principles of chronotherapy.

Long-term exposure to space's microgravity alters the time structure of heart rate variability of astronauts

Background

Spaceflight alters human cardiovascular dynamics. The less negative slope of the fractal scaling of heart rate variability (HRV) of astronauts exposed long-term to microgravity reflects cardiovascular deconditioning. We here focus on specific frequency regions of HRV.

Methods

Ten healthy astronauts (8 men, 49.1 ± 4.2 years) provided five 24-hour electrocardiographic (ECG) records: before launch, 20.8 ± 2.9 (ISS01), 72.5 ± 3.9 (ISS02) and 152.8 ± 16.1 (ISS03) days after launch, and after return to Earth. HRV endpoints, determined from normal-to-normal (NN) intervals in 180-min intervals progressively displaced by 5 min, were compared in space versus Earth. They were fitted with a model including 4 major anticipated components with periods of 24 (circadian), 12 (circasemidian), 8 (circaoctohoran), and 1.5 (Basic Rest-Activity Cycle; BRAC) hours.

Findings

The 24-, 12-, and 8-hour components of HRV persisted during long-term spaceflight. The 90-min amplitude became about three times larger in space (ISS03) than on Earth, notably in a subgroup of 7 astronauts who presented with a different HRV profile before flight. The total spectral power (TF; p < 0.05) and that in the ultra-low frequency range (ULF, 0.0001–0.003 Hz; p < 0.01) increased from 154.9 ± 105.0 and 117.9 ± 57.5 msec² (before flight) to 532.7 ± 301.3 and 442.4 ± 202.9 msec² (ISS03), respectively. The power-law fractal scaling β was altered in space, changing from -1.087 ± 0.130 (before flight) to -0.977 ± 0.098 (ISS01), -0.910 ± 0.130 (ISS02), and -0.924 ± 0.095 (ISS03) (invariably p < 0.05).

Interpretation

Most HRV changes observed in space relate to a frequency window centered around one cycle in about 90 min. Since the BRAC component is amplified in space for only specific HRV endpoints, it is likely to represent a physiologic response rather than an artifact from the International Space Station (ISS) orbit. If so, it may offer a way to help adaptation to microgravity during long-duration spaceflight.

Effect of Breed on Plasma Endothelin-1 Concentration, Plasma Renin Activity, and Serum Cortisol Concentration in Healthy Dogs

BACKGROUND

There are breed differences in several blood variables in healthy dogs.

OBJECTIVE

Investigate breed variation in plasma endothelin-1 (ET-1) concentration, plasma renin activity, and serum cortisol concentration.

ANIMALS

Five-hundred and thirty-one healthy dogs of 9 breeds examined at 5 centers (2-4 breeds/center).

METHODS

Prospective observational study. Circulating concentrations of ET-1 and cortisol, and renin activity, were measured using commercially available assays. Absence of organ-related or systemic disease was ensured by thorough clinical investigations, including blood pressure measurement, echocardiography, ECG, blood and urine analysis.

RESULTS

Median ET-1 concentration was 1.29 (interquartile range [IQR], 0.97-1.82) pg/mL, median cortisol concentration 46.0 (IQR, 29.0-80.8) nmol/L, and median renin activity 0.73 (IQR, 0.48-1.10) ng/mL/h in all dogs. Overall, breed differences were found in ET-1 and cortisol concentrations, and renin activity (P < .0001 for all). Pair-wise comparisons between breeds differed in 67% of comparisons for ET-1, 22% for cortisol, and 19% for renin activity, respectively. Within centers, breed differences were found at 5/5 centers for ET-1, 4/5 centers for cortisol, and 2/5 centers for renin activity. Newfoundlands had highest median ET-1 concentration, 3 times higher than Cavalier King Charles Spaniels, Doberman Pinschers, and Dachshunds. Median renin activity was highest in Dachshunds, twice the median value in Newfoundlands and Boxers. Median cortisol concentration was highest in Finnish Lapphunds, almost 3 times higher than in Boxers.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed variation might be important to take into consideration when interpreting test results in clinical studies.

Effect of feeding behavior on circadian regulation of endothelin expression in mouse colon

AIMS

The function, regulation and gene expression of the endothelin (ET) system in the intestine is not well understood. We investigated the dependence on feeding schedule and biological clock of the regulation of ET-1 gene expression in mouse colon.

MAIN METHODS

Mice were fed freely, fasted for 48 h and re-fed after fasting.

KEY FINDINGS

Where indicated ET-1 gene expression was highest in the colon compared with other tissues examined in fasted mice. Fasting increased the level, while maintaining the rhythmicity, of ET-1 gene expression in epithelial colonic tissue. Re-feeding, however, decreased ET-1 gene expression and suppressed rhythmic oscillation, and the rhythmicity also changed for gene expression for circadian clocks, period-1 and period-2 (Per1 and Per2). Furthermore, the decrease in ET-1 gene expression induced by re-feeding was blocked by pre-treatment with hexamethonium and atropine. The daily change in ET-1 gene expression in colon, which depends on feeding schedule via the autonomic nervous system, is synchronized with peripheral circadian oscillators under conditions of free feeding and fasting but not re-feeding. The decrease in ET-1 gene expression in the proximal colon induced by re-feeding occurs via the nervous system.

SIGNIFICANCE

ET-1 plays an important physiological role, which is dependent on feeding behavior.

Endothelin-1 and psychosocial risk factors for cardiovascular disease: a systematic review

OBJECTIVES

Psychosocial factors (i.e., social environment and emotional factors) contribute to an increased risk of cardiovascular disease (CVD). Perturbation in a potent vasoconstrictive peptide endothelin (ET)-1 could be one of the mechanisms linking psychosocial factors to CVD. Our aim was to evaluate the literature on the relationship between plasma ET-1 and psychosocial risk factors for CVD.

METHODS

MEDLINE and PsycINFO databases were searched for articles on human studies published in peer-reviewed English-language journals through September 2012.

RESULTS

Of the 20 studies that met the inclusion criteria, 14 were experimental studies of acute psychological/mental challenges and 6 were observational studies of psychological and social factors. The inferences drawn from this review were as follows: a) laboratory-induced acute psychological/mental stress may result in exaggerated plasma ET-1 release in those with CVD and those at risk for CVD (positive studies: 5/10); b) chronic/episodic psychosocial factors may have a positive relationship to plasma ET-1 (positive studies: 3/5); and c) race (African American), sex (male), and individual differences in autonomic and hemodynamic responses to stress (parasympathetic withdrawal and elevated blood pressure responsiveness) may moderate the relationship between psychosocial factors and plasma ET-1.

CONCLUSIONS

This review indicates that psychosocial risk factors for CVD are associated with elevated plasma ET-1; however, the relatively small number of studies, methodological differences, and variable assessment tools preclude definitive conclusions about the strength of the association. Specific suggestions regarding the selection of psychosocial factors, optimization of acute challenge protocols, and standardization of methods and timing of the ET-1 measures are provided.

Spontaneous short-term variations of circulating endothelin-1 in pulmonary hypertension

Endothelin-1 (ET-1) is overexpressed in pulmonary arteries of pulmonary hypertension (PH) patients and contributes to the sustained vasoconstriction, remodeling process, and thrombosis of vessels that underlie development and progression of this disease. Increased circulating ET-1 correlates with markers of PH severity, and ET-1 is regarded as a potential diagnostic and prognostic biomarker in PH. Because the within-individual variability measured in PH patients and in healthy subjects contributes to determine the biomarker predictive value and must be taken into account to establish cutoff values, we determined the short-term variability of circulating ET-1 in controls and in PH patients.

Chronobiology of hemostasis and inferences for the chronotherapy of coagulation disorders and thrombosis prevention

The hemostatic system in its multiple components displays an intricate organization in time which is characterized by circadian (approximately 24-hour), circaseptan (approximately 7-day), menstrual (approximately monthly), and circannual (approximately yearly) bioperiodicities. The interaction of the rhythms of the variables participating in hemostasis determine transient risk states of thromboembolic events, including myocardial infarction and stroke, and of hemorrhage and hemorrhagic events, each with a unique timing. The circadian staging of the rhythms in vascular, cellular, and coagulation factors that favors blood coagulation and thrombosis coincides with the daily minimum in fibrinolytic activity; as a result there is elevated risk in the morning of acute myocardial infarction and stroke. Similar hemostatic rhythms may determine the epidemiology of thromboembolic and hemorrhagic events during the week, month and year. This article focuses on the large-amplitude circadian rhythms operative in the hemostatic system. Their implication for preventive and curative pharmacotherapy of hemostatic disorders is presented, with discussion of related problems.

Circulating endothelin parallels arterial blood pressure during sleep in healthy subjects

OBJECTIVE

To characterize plasma endothelin 1 (ET-1) and arterial blood pressure (ABP) time courses during the first complete non-rapid eye movement (NREM)-REM sleep cycle in healthy subjects, together with plasma renin activity (PRA) and plasma atrial natriuretic peptide (ANP).

METHODS

Heart rate (HR), intra-arterial blood pressure and sleep electroencephalographic activity were recorded continuously during the night in eight healthy 20-28-year-old males. Blood was sampled every 10 min during their first complete sleep cycle for simultaneous measurements of plasma ET-1, PRA and ANP.

RESULTS

Circulating ET-1 demonstrated significant variations during the sleep cycle (p<0.0001) that paralleled those of ABP (p<0.05) and HR (p<0.005), with a minimum during NREM sleep and a maximum during REM sleep. ET-1 time course opposed that of PRA which increases during NREM sleep and decreases during REM sleep (p<0.0005). Plasma ANP did not demonstrate systematic variation in relation with the sleep cycle.

CONCLUSION

Circulating ET-1, which parallels variations of ABP, may participate in ABP regulation during sleep in healthy subjects, in association with the renin-angiotensin system.

Chronomics for chronoastrobiology with immediate spin-offs for life quality and longevity

Effects of geomagnetic disturbance on heart rate variability (HRV), the 1/f fractal scaling in particular, are being assessed in adults living at high latitude, where magnetic storms are more frequent and more intense than at lower latitudes. The latter may constitute a signal or a proxy, and possibly a mechanism underlying both undesirable and desirable effects, depending upon circumstances yet to be elucidated. Any circadecadal stage-dependence of morbidity and/or mortality from certain conditions such as myocardial infarctions remains to be studied in both adult and pediatric populations. Further work could thus examine whether any associations of geomagnetic disturbances may account, at least in part, through effects upon the circulation, for long-term infra-annual changes, possibly anchored in the population's gene pool, observed in a number of anthropologic measurements at birth as well as in other population statistics. In order to assess the development of several chronome components of the electrocardiogram (ECG), around-the-clock ambulatory ECG were recorded from 19 infants (25 days-3 months of age), 22 children (3-9 years of age), 18 boys and girls (10-14 years of age), pubertal boys (15-20 years of age), and 10 young men (21-29 years of age). Time- and frequency-domain measures of HRV were obtained by spectral analysis, using the maximal entropy method (MEM). The frequency of detection of the circadian, circasemidian and circaoctohoran components, with periods of about 24, 12 and 8 h, respectively, was compared among the five groups for several HRV endpoints, notably 1/f fractal scaling, total spectral power within a 5-min span, and its distribution into several frequency regions. A circadian component is already detectable in a sizeable proportion of infants and children for most of the HRV indices considered. The incidence of detection of the circadian component increases with age for the spectral power in different frequency regions, notably around 10.5 s ("LF") and around 3.6 s ("HF"); it peaks around puberty for 1/f in our data; and it did not detectably change with age for the total spectral power. Similar changes with age are not observed for the circasemidian or circaoctohoran components. The latter characterizes primarily 1/f and less so the about 3.6 s power ("HF"). Several aspects of the HRV chronome may thus develop differently as a function of age. In 2000, we began a community-based study named "Longitudinal Investigation of Longevity and Aging in Hokkaido County (LILAC study)". The ambulatory blood pressure (BP) of middle-aged subjects, aged 40-74 years, was monitored 7-day/24-h, and the cardiovascular and neurobehavioral functions of elderly people above 75 years were evaluated. Our goal was the prevention of stroke and myocardial infarction and the decline in cognitive function of the elderly in a community. Of 115 elderly people recruited in a longitudinal community-based study in 2000, 72 completed yearly follow-ups in 2002. A cardiovascular score based on BP, pulse wave velocity, and 1-h ECG-based HRV endpoints served to distinguish between normal, mildly disordered, or disordered participants. A comparison of cognitive function in 2002 vs. 2000, assessed with the MMSE, HDSR, the Up & Go and Functional Reach tests, gauged any effect of social intervention. Cognitive function was maintained or improved, especially for people suffering from hypertension, tachycardia, or a decreased HRV, suggesting that cardiovascular function is a major factor affecting cognitive function.

A chronomic tree of life: ontogenetic and phylogenetic ‘memories’ of primordial cycles — keys to ethics

A scientific optimization may become possible in ethics to the extent to which any reproducible since cyclic features of spirituality and of criminality become measurable. Should either or both the 'good' or the 'bad' be found to be at least passively influenced by cyclic physical environmental factors, as is putatively the case, these aspects of behavior may eventually become actively manipulable, perhaps utilizable for human survival. Toward this goal, chronomics has already mapped time structures in religious behavior that can lead to a study of underlying geographic/geomagnetic latitude-associated mechanisms. This paper, with further but clearly insufficient data, revealing the hurdle of relative brevity of the available time series constitutes a plea for much longer and denser worldwide time series, for further endeavors in various methods of analyses, some of which are promisingly available.

Disruption of Ultradian and Circadian Rhythms of Blood Pressure in Nondipper Hypertensive Patients

Ultradian rhythms in blood pressure (BP) are known to exist, but their modification in hypertension is largely unknown. The present study was undertaken to assess the integrity of ultradian and 24-hour BP rhythms in dipper (n=100) and nondipper (n=20) hypertensive patients compared with 44 dipper normotensive individuals. Fourier analysis was used to fit ultradian (12, 8, and 6 hour) and 24-hour rhythms in BP and heart rate (HR). Mesor, amplitude, and acrophase were calculated for individual and overall rhythm curves. All subjects showed significant ultradian or 24-hour BP and HR rhythms. Systolic and diastolic BP mesor was higher in hypertensive patients compared with normotensive patients. The percentage of variability in ambulatory BP that could be explained by fitting ultradian and 24-hour rhythms was reduced in nondippers compared with normotensives or dippers. Amplitude of ultradian and 24-hour rhythms in BP increased in dippers and decreased in nondippers. Ultradian and 24-hour rhythms in HR did not differ among the 3 groups examined. Results indicate that in nondippers, blunted ultradian and 24-hour rhythm amplitude in BP was accompanied by a loss of rhythm integrity.

Chronomics: circadian and circaseptan timing of radiotherapy, drugs, calories, perhaps nutriceuticals and beyond

We suggest a putative benefit from timing nutriceuticals (substances that are both nutrients and pharmaceuticals) such as antioxidants for preventive or curative health care, based on the proven merits of timing nutrients, drugs, and other treatments, as documented, i.a., in India. The necessity of timing melatonin, a major antioxidant, is noted. A protocol to extend the scope of chronoradiotherapy awaits testing. Imaging in time by mapping rhythms and broader time structures, chronomes, for earliest diagnoses, for example detection of vascular disease risk, is recommended. The study of rhythms and broader chronomes leads to a dynamic functional genomics, guided by imaging in time of free radicals and antioxidants, amongst many other variables.

Neuropeptide chronomics in clinically healthy young adults: circaoctohoran and circadian patterns

Endothelin-1 (ET-1) undergoes an about 8-h (circaoctohoran) rather than a circadian variation in clinical health. Herein, 24 h plasma concentrations of vasoactive intestinal peptide (VIP), substance P (SP), neuropeptide Y (NpY), and cortisol used as reference, were obtained from 20 healthy young adults starting at 07:00 or 19:00 h. Like ET-1, SP and NpY undergo a circaoctohoran variation, whereas VIP is circadian rhythmic, peaking during the night, some 8 h prior to the circadian acrophase of cortisol. Maps of circadian and extra-circadian patterns may serve for screening, diagnosis and a better understanding of mechanisms underlying the etiology of various diseases.

Transdisciplinary unifying implications of circadian findings in the 1950s

Afew puzzles relating to a small fraction of my endeavors in the 1950s are summarized herein, with answers to a few questions of the Editor-in-Chief, to suggest that the rules of variability in time complement the rules of genetics as a biological variability in space. I advocate to replace truisms such as a relative constancy or homeostasis, that have served bioscience very well for very long. They were never intended, however, to lower a curtain of ignorance over everyday physiology. In raising these curtains, we unveil a range of dynamics, resolvable in the data collection and as-one-goes analysis by computers built into smaller and smaller devices, for a continued self-surveillance of the normal and for an individualized detection of the abnormal. The current medical art based on spotchecks interpreted by reference to a time-unqualified normal range can become a science of time series with tests relating to the individual in inferential statistical terms. This is already doable for the case of blood pressure, but eventually should become possible for many other variables interpreted today only based on the quicksand of clinical trials on groups. These ignore individual differences and hence the individual's needs. Chronomics (mapping time structures) with the major aim of quantifying normalcy by dynamic reference values for detecting earliest risk elevation, also yields the dividend of allowing molecular biology to focus on the normal as well as on the grossly abnormal.

Distribution and daily variations of PACAP in the chicken brain

Levels of PACAP38 were measured in different areas of the chicken brain under various lighting conditions by radioimmunoassay (RIA). Selected groups of animals were maintained under light for 14 h alternating with 10 h of darkness (LD), reversed lighting conditions (DL) and constant light (LL) or constant dark (DD). Daily variations of PACAP levels were observed in the brainstem, diencephalon, telencephalon and retina. In the brainstem and diencephalon, levels of PACAP increased during subjective nighttime, except in the DL group where levels were elevated between 15-21 h. In the telencephalon, the lowest level of PACAP was measured between 12-21 h except in the DL group where two peaks occurred at 18 and 03 h. In the retina, all 4 groups showed a similar level and pattern, with lowest levels during midday hours. No daily variation was observed in the pineal gland. According to the present observations, it is suggested that PACAP levels differ in several areas of the chicken brain under various lighting conditions and photic stimuli do not appear to be the main regulators of the circadian variations of PACAP.

Feedsidewards: intermodulation (strictly) among time structures, chronomes, in and around us, and cosmo-vasculo-neuroimmunity. About ten-yearly changes: what Galileo missed and Schwabe found

The spectrum of biological rhythms is extended far beyond circadians, circannuals, and ultradians, such as 1.5-hourly melatonin and 8-hourly endothelin-1 (ET-1) rhythms by statistics of natality, growth, morbidity, and mortality, some covering decades or centuries on millions of individuals. These reveal infradian cycles to be aligned with half-weekly rhythms in ET-1, weekly and half-yearly ones in melatonin, and even longer--about 50-, about 20-, and about 10-year cycles found in birth statistics. About daily, weekly, yearly, and ten-yearly patterns are also found in mortality from myocardial infarctions; the 10-yearly ones are also in heart rate and its variability; in steroid excretion, an aspect of resistance, for example, to bacteria; and in the genetic changes of the bacteria themselves. Automatic physiological measurements cover years and, in one case, cover a decade; the latter reveal an about 10-year (circadecennial) cycle. ECGs, covering months beat-to-beat, reveal circaseptans, gaining prominence in response to magnetic storms or after coronary artery bypass grafting. A spectrum including cycles from fractions of 1 Hz to circasemicentennians is just one element in biological time structures, chronomes. Chaos, trends, and any unresolved variability are the second to fourth elements of chronomes. Intermodulations, feedsidewards, account for rhythmically and thus predictably recurring quantitive differences and even for opposite treatment effects of the same total dose(s) of (1) immunomodulators inhibiting or stimulating DNA labeling of bone in health or speeding up versus slowing down a malignant growth and thus shortening or lengthening survival time, or (2) raising or lowering blood pressure or heart rate in the vascular aspect of the body's defense. Latitude-dependent competing photic and nonphotic solar effects upon the pineal are gauged by alternating yearly (by daylight) and half-yearly (by night) signatures of circulating melatonin at middle latitudes and by half-yearly signatures at noon near the pole. These many (including novel near 10-yearly) changes, for example, in 17-ketosteroid excretion, heart rate, heart rate variability, and myocardial infarction in us and those galactic, solar, and geophysical ones around us have their own special signatures and contribute to a cosmo-vasculo-immunity and, if that fails, to a cosmo(immuno?) pathology.

About 8- and approximately 84-h rhythms in endotheliocytes as in endothelin-1 and effect of trauma

Population densities (PD) of capillaries (C) and endotheliocytes (E) were determined in pinnal dermis of C57BL mice before and after trauma. Moving (and overall) least-squares spectra before trauma detected in EPD (versus CPD) pronounced 3.5-day (circasemiseptan) and 8-h oscillations corresponding to components of the endothelin-1 chronome in human blood plasma reported earlier. Circadians were more pronounced in CPD. After trauma, circasemiseptan oscillations appeared also in CPD; their period gradually shortened and in two weeks split into about 2.5- and about 4.5-day oscillations; and circadian components became very pronounced. The pre-traumatic chronome was not restored within three weeks following trauma.

The biological week and broader time structures (chronomes): in memory of Gunther Hildebrandt

Data illustrating the biological week and chronomes are presented in recognition of extensive work of G. Hildebrandt.