Season's appreciations.

To follow the tradition set by the late Franz Halberg, highlights of research performed over the last year from his Minnesota Center are summarized. They illustrate the broad international cooperation enjoyed by his center and the diversity of applications of the discipline he founded. The results briefly summarized herein in the form of an annotated bibliography are a testimony that his legacy continues to live on and constitutes a tribute to his memory.

Circadian variation in multiple sclerosis of oxidative stress marker of DNA damage. A potential cancer marker?

OBJECTIVE: To investigate circadian rhythm (CR) of urinary creatinine and 8-hydroxy-2-deoxyguanosine (8-OHdG) in patients with Multiple Sclerosis (MS) and to present concentrations of this DNA damage marker, 5 years prior to mastectomy, in one MS study subject, and 2 years prior to biopsy confirmed a carcinoma (CA) of the prostate in one non-MS subject. MATERIALS AND METHODS: Eleven subjects with MS (6 women 36-52 years of age and 5 men 51-68 years) volunteered for this study, carried out at Edward Hines Jr., Medical Center. Subjects were offered a general hospital diet (2400 cal in total/24h) at 16:30h, 07:30h and 13:00h. The dark (sleep) phase of the light-dark cycle extended from 22:30h to 06:30h with brief awakening for sampling at 01:00h, and 04:00h. Urine samples were collected for consecutive 3h spans beginning at 16:00-19:00h and were analyzed for creatinine and 8-OHdG. Twelve men (including 3 with type 2 diabetes) provided 21 profiles according to the same protocol used for comparison. In addition, 10 healthy women provided 24h urine samples. Statistical analysis of data was performed using the Single-Cosinor and Population-Mean Cosinor. RESULTS: A CR was detected for creatinine in healthy men (p < 0.001) but not for MS patients. Urinary creatinine concentrations were lower in MS women than in healthy women (p = 0.015) and were lower in MS women than in men healthy or with MS (p < 0.001): Women; MS 655 +/- 76; H 1381 +/- 316; Men, MS 1830 +/- 285; H 1532 +/- 265 mg/24h vol. A CR was evident in 8-OHdG in MS (p = 0.007) and in non-MS subjects (p < 0.001) with highest values occurring at about 16:45h. The average concentrations of 8-OHdG in MS patients were similar to those in healthy subjects: Women, MS 589 +/- 125; H 794 +/- 318; Men, MS 504 +/- 156; H 591 +/- 134 picomoles/kg bw/24h vol. The 8-OHdG concentrations of a MS patient, later diagnosed with breast cancer, were found to exceed the upper 95% prediction limit in health. An increased 8-OHdG level was also noted in a non-MS subject who 2 years later received a biopsy-confirmed diagnosis of prostate CA. CONCLUSIONS: Despite the small number of subjects in this study, a statistically significant CR was documented for 8-OHdG in urine of subjects with MS. Interestingly, the increased concentrations of DNA damage marker, the 8-OHdG, 5 years prior to mastectomy and the 2 years prior to affirmative diagnosis of prostate CA, could be the most significant clinical observations of this study. Follow-up studies of a larger population of subjects would, thus, be required to ascertain the predictive validity of such challenging observation.

Circasemidian rather than circadian variation of circulating osteoprotegerin in clinical health.

Osteoprotegerin (OPG) serves as a soluble decoy receptor for RANKL to inhibit osteoclast formation and activity. Hormones such as PTH and glucocorticoids have been reported to decrease OPG concentrations, while estrogens, transforming growth factor b, related bone morphogenic factor and thrombopoietin reportedly enhance the OPG production in the osteoblastic and bone stromal cells. Since bone turnover shows a prominent circadian rhythm in laboratory animals and humans, with bone resorption increasing at night, we investigated the time structure of circulating OPG concentrations in a group of nine healthy subjects (six women and three men; in the age range of 26-49 years). Blood samples for OPG determination were collected every 4 h for 24 h on the same day, starting at 08:00 in the morning. Data were analyzed by inferential statistical procedures, including the single and population-mean cosinor. A 12-h component was found to characterize serum OPG concentrations (P = 0.038) with peak concentrations around noon and midnight. No statistically significant circadian rhythm of OPG concentrations could be found by cosinor in our study population. The mean 24-h OPG concentration was higher in women than in men (mean +/- S.E.: 3.13 +/- 0.44 vs. 1.94 +/- 0.26 pmol/l, Student t = 2.325, P = 0.053). Since PTH concentrations also exhibit a bimodal pattern along the 24-h scale, PTH may be tested as a putative determinant of the observed changes in serum concentrations of osteoprotegerin.

Circadian rhythm of maternal blood pressure and fetal growth.

This study aimed at examining any relation between the circadian variation in blood pressure (BP) in human pregnancy and fetal growth. A prospective study included 52 pregnant women monitored during the third trimester of pregnancy. There were 33 uncomplicated pregnancies with normal fetal growth (Group 1) and 19 pregnancies complicated by intrauterine growth retardation (IUGR), confirmed at birth (Group 2). Ten women (five in each group) had pregnancy-induced hypertension. All women were hospitalized and followed a similar daily routine. BP was recorded with an automatic wearable device. Measurements were obtained every 20 min for 24 +/- 1 h. BP profiles were analyzed by conventional statistical methods and by cosinor, involving the least squares fit of cosine curves with an anticipated period (24 h) to the data. BP parameters, fetal outcome, demographic and obstetric characteristics were compared between the two groups. Logistic regression and multivariate analyses were used to assess factors putatively associated with fetal outcome. The circadian amplitude of diastolic BP was found to be larger in normotensive women with IUGR. As gauged by odds ratios (OR), the circadian amplitude of diastolic BP (OR = 1.7, 95% CI: 1.1-2.8; P = 0.03) and hematocrit (OR = 1.4, 95% CI: 1.0-1.9; P = 0.04) were the only variables positively and independently associated with IUGR. In the presence of maternal hypertension, the circadian amplitude of systolic BP was negatively associated with IUGR (OR = 0.7, 95% CI: 0.5-1.0; P = 0.03). A larger circadian variation in diastolic BP, rather than a difference in the mean value of systolic or diastolic BP, was found to be statistically significantly associated with IUGR. This study adds another condition in which the circadian BP amplitude constitutes a harbinger of elevated risk, apart from an association with a shortened lifespan in the absence or presence of malignant hypertension and with an increased risk of stroke and nephropathy reported earlier.

Circadian periodicity of plasma lipid peroxides and other anti-oxidants as putative markers in gynecological malignancies.

BACKGROUND: The chronome (from chronos, time, and nomos, rule), or time structure, of lipid peroxidation and anti-oxidant defense mechanisms may relate to prevention and curative chronochemotherapeutic efficacy and management. PATIENTS AND METHODS: Newly diagnosed women with gynecological malignancies (N = 30), 30-60 years of age, and age-matched clinically healthy women (N = 35) provided blood samples every 6 hours for 24 hours under standardized conditions. Plasma malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, and serum ascorbate, urate and high-density lipoprotein cholesterol (HDL-C) concentrations were determined. RESULTS: Each variable underwent circadian variation (p < or = 0.002). Patients differed from controls by their overall chronome-adjusted mean value (MESOR) and by the circadian dynamics in the spectral element of their chronome. CONCLUSION: Chronomes of putative anti- and pro-oxidants should be mapped to explore their putative chemotherapeutic role as markers in cancer chronoprevention and management of established disease.

Blood pressure outcomes of dental patients screened chronobiologically: a seven-year follow-up.

BACKGROUND: This article is a follow-up on a 1998 article in JADA. The blood pressure, or BP, of 23 of 24 normotensive patients was monitored at 15-minute intervals for a total of nine days, in three consecutive sessions of four, two and three days, respectively, separated by a few weeks. METHODS: Twelve patients were reached by phone seven years after the prior chronobiologically interpreted monitoring to ascertain their cardiovascular status since the initial monitoring. RESULTS: Only two of the 12 patients reached in follow-up had abnormalities in all three sessions, and only these two patients reported having experienced an adverse vascular event (one a myocardial infarction, the other coronary artery bypass graft surgery). The difference in outcome between the patients with chronobiological abnormality in all three sessions vs. the pool of those with abnormality in only two, one or none of the sessions is statistically significant. CONCLUSIONS: Even a five-day (and sometimes a longer) profile, while greatly preferred to single measurements, may not suffice for a definitive diagnosis of certain patients. Retrospectively, the 864 measurements, on the average, on each person in our study could have served for a recommendation to each person. Chronobiologically interpreted BP and heart rate monitoring for a week or longer as a start detects high-risk states that may be missed by conventional casual measurements that are rarely accompanied by one-day profiles. CLINICAL IMPLICATIONS: The dentist has an important opportunity for conveying the importance of monitoring BP and heart rate for a week to detect an abnormal variability, and for implementing this monitoring. Dentists can educate patients regarding the need for screening and for interpreting the results for variability, and contribute to their overall health by referring them to their physicians when treatment is indicated.

The brain decade in debate: IV. Chronobiology

The present article is the adapted version of an electronic symposium organized by the Brazilian Society of Neuroscience and Behavior (SBNeC) which took place on June 14, 2000. The text is divided into three sections: I. The main issues, II. Chronodrugs, and III. Methods. The first section is dedicated to the perspectives of chronobiology for the next decade, with opinions about the trends of future research being emitted and discussed. The second section deals mostly with drugs acting or potentially acting on the organism's timing systems. In the third section there are considerations about relevant methodological issues concerning data analysis

Meta-analysis of sequential luteal-cycle-associated changes in human breast tissue.

We chronobiologically estimate the time relations of physiological and morphological changes in breast tissue during the luteal phase of the menstrual cycle, as a cascade led by the progesterone peak. The timing and uncertainties of maxima in epithelial mitotic frequency, breast and epithelial volume, breast surface temperature, water content, blood flow and apoptosis are given as parts of a rhythmic element in a broader time structure or chronome.

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.

Spin-offs from blood pressure and heart rate studies for health care and space research.

Evidence here cited underlies resolutions at international meetings to initiate a chronobiology project for health improvement. This project demonstrates expeditiously the feasibility and the health benefits of incorporating chronomedical considerations in the diagnosis, treatment, and prevention of one (or a few closely related) vascular (and oncological) diseases, that have high awareness and importance in the public perspective. Thereby, chronomedicine should become a mainstream basic and applied speciality leading to continual improvement in national/international health status. Reference data obtained for health care can also serve to give a better understanding of the relationship between the terrestrial biosphere and cosmoi near and far.

Chronomedical aspects of oncology and geriatrics.

Extensive laboratory evidence on the merits of cancer chronotherapy is validated by the doubling of 2-year disease-free survival rate obtained by the chronoradiotherapy of patients with very advanced perioral cancers and by the quadrupling of the 5-year survival achieved by the chronochemotherapy of patients with advanced ovarian and bladder cancer. Miniaturized monitors for marker rhythmometry of tumor and core temperature recorded over long spans should facilitate the optimization of treatment by timing, while also serving the purpose of earliest intervention. The likelihood of a cure should be increased by focusing upon the now extensively documented tumor marker rhythms that may show time structure (chronome) alterations before exceeding the physiological range (that is otherwise neglected as one of random variation), and before overt symptoms appear.

Enhanced circasemiseptan (about 3.5-day) variation in the heart rate of cancer patients?

In addition to prominent circadian and circannual components, an about half-weekly (circasemiseptan) pattern was shown earlier to characterize mitotic activity in cancer patients. A circasemiseptan variation in heart rate and circadian rhythms in heart rate and axillary temperature of cancer patients are assessed herein. These variables could be tested as putative marker rhythms for the optimization of radio- and/or chemotherapy by timing which, from a practical viewpoint, may be easier to implement along the scale of the week than that of the day.

The chronobiology of prostate-specific antigen (PSA): case report and chrono-metaanalysis.

The circadian profiles of circulating PSA of a 72-year-old man (FH) and of 11 other clinically relatively healthy men are compared. The time course of FH's PSA was also followed longitudinally with single samples for over 3 years. A transient peak in PSA exceeding the upper time-unspecified age-corrected reference limit prompted a retrospectively premature biopsy which indicated prostatitis. Watchful waiting and additional PSA determinations may be the preferred approach before biopsy, notably in the elderly, for reasons of cost and invasiveness of the procedure. The load associated with a biopsy is also evaluated by a cardiovascular response.

Chronomes render predictable the otherwise-neglected human "physiological range": position paper of the BIOCOS project. BIOsphere and the COSmos.

On June 30, 1997, the Russian Academy of Medical Sciences convened a special session at its headquarters to discuss and, at the end of this meeting, to unanimously endorse a project on "The BIOsphere and the COSmos" (BIOCOS), a follow-up on various international resolutions reviewed elsewhere [1]. BIOCOS recommends the introduction of the science of the body's time structure, chronobiology [2], into basic science and health and environmental care via national physiological and physical monitoring and educational endeavors. More specifically, BIOCOS aims at the collection and archivization for basic and applied purposes at different latitudes and longitudes of physical and physiological time structures, or chronomes [1, 3]. The first step of BIOCOS is the systematic mapping of variation in human blood pressure and heart rate from womb to tomb and the opportunistic mapping of other variables in human and other life forms. On July 1, 1997, BIOCOS was introduced at the XXXIII International Congress of the International Union for Physiological Sciences in St. Petersburg, in the context of a symposium on "Adaptation to the Environment". Thereafter, BIOCOS was presented in a course on chronobiology in Mexico City, August 27-30, 1997, in lectures at Masaryk University, Brno, Czech Republic (September 1, 1997); at a meeting on "Chronobiology with roots in the cosmos", September 2-6, 1997, in Stara Lesna, Slovakia, under the auspices of the Slovak Medical Society; at Safarik University in Kosice (September 8) and the Institute of Clinical Endocrinology in Lubochna (September 9), both in Slovakia and at the International Conference on the Pineal Gland and Cancer (October 2-5, 1997) in Blaubeuren, Germany.

Interpreting vital sign profiles for maximizing patient safety during dental visits.

Concerns about local anesthetics and dental treatment stress are still prevalent in today's medical and dental communities. The authors conducted 24-hour monitoring of heart rate and blood pressure for 23 patients undergoing two root planing procedures and a single periodontal surgical procedure. Chronobiologic analysis of circadian blood pressure and heart rate rhythms revealed that neither epinephrine vasoconstrictor in anesthetics nor increased invasiveness of the procedure resulted in statistically significant deviations from regular, individualized blood pressure rhythms. For surgical appointments, time of day had the greatest effect on cardiovascular variables, with the greatest elevations in blood pressure seen for surgery at 8 a.m. and the largest blood pressure decreases seen for surgery at 2 p.m.

Studies on circadian periodicity of urinary corticoids in carcinoma of the breast.

The circadian periodicity of urinary 17-ketogenic steroids (17-KGS), 17-ketosteroids (17-KS) and creatinine (Cr) was studied preoperatively and on the 9th postoperative day in 25 histopathologically proved breast cancer patients and in 15 healthy Indian women under tropical conditions. A statistically significant rhythm was observed in healthy participants for all three variables. Urinary corticoids were markedly elevated in breast cancer patients irrespective of the stage of the disease in comparison with healthy controls. The degree of elevation was more pronounced preoperatively in advanced stage breast cancer in comparison with other groups. After mastectomy, the values of all three variables declined markedly, approaching usual values with a circadian rhythm resembling the pattern found in clinical health.

Endothelin-1's chronome indicates diabetic and vascular disease chronorisk.

Plasma endothelin-1 was measured around the clock in 72 subjects. Cosinor methods were used to assess circadian and other recurrent variation and trends, that is, the time structure (chronome) of this peptide. Multifactorial analyses of variance and linear regressions assessed chronome alterations associated with different risk factors: diabetes, obesity, high cholesterol, high blood pressure, vascular disease, smoking, and age. The rhythm-adjusted mean (MESOR) of endothelin-1 is elevated in diabetes and vascular disease. Diabetes is also associated with a larger circadian amplitude. A circadian variation in a subgroup of low-risk subjects is modulated by components with both lower and higher frequency.

[Chronobiology in medicine and surgery]. / Cronobiología en medicina y cirugía.

Chronobiology studies predictable variations, rhythms and trends in all forms of life. Each physiologic variable or system in an organism has a time structure which is genetically anchored and capable of being expressed in the absence of external cycles. However, it is normally adjusted by geophysical changes. Chronobiology quantifies rhythms by providing measures of amplitude and timing (phase and period), and a mean more precise than the arithmetic mean. The correct measurement of biological rhythms has led to considerable advances in the understanding of their underlying mechanisms of generation and expression. The use of information on rhythms is opening new opportunities in the prevention, diagnosis and treatment of disease. Chronobiology is also effective in the improvement of the quality of life by teaching self-help to the healthy individual.