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Biomedical subjects

F Halberg

Publications and source records attributed to F Halberg.

At least 55 records · Page 3Linked to original sources
PubMed2002

Is motivation influenced by geomagnetic activity?

To eventually build a scientific bridge to religion by examining whether non-photic, non-thermic solar effects may influence (religious) motivation, invaluable yearly world wide data on activities from 1950 to 1999 by Jehovah's Witnesses on behalf of their church were analyzed chronobiologically. The time structure (chronome) of these archives, insofar as it is able to be evaluated in yearly means for up to half a century, was assessed. Least squares spectra in a frequency range from one cycle in 42 to one in 2.1 years of data on the average number of hours per month spent in work for the church, available from 103 different geographic locations, as well as grand totals also including other sites, revealed a large peak at one cycle in about 21 years. The non-linear least squares fit of a model consisting of a linear trend and a cosine curve with a trial period of 21.0 years, numerically approximating that of the Hale cycle, validated the about 21.0-year component in about 70% of the data series, with the non-overlap of zero by the 95% confidence interval of the amplitude estimate. Estimates of MESOR (midline-estimating statistic of rhythm, a rhythm (or chronome) adjusted mean), amplitude and period were further regressed with geomagnetic latitude. The period estimate did not depend on geomagnetic latitude. The about 21.0-year amplitude tends to be larger at low and middle than at higher latitudes and the resolution of the about 21.0-year cycle, gauged by the width of 95% confidence intervals for the period and amplitude, is higher (the 95% confidence intervals are statistically significantly smaller) at higher than at lower latitudes. Near-matches of periods in solar activity and human motivation hint that the former may influence the latter, while the dependence on latitude constitutes evidence that geomagnetic activity may affect certain brain areas involved in motivation, just as it was earlier found that it is associated with effects on the electrocardiogram and anthropometry.

Brain↗
PubMed2002

Self-measurement and ambulatory monitoring of blood pressure: a subject's chronobiological perspective.

Population studies show the direct benefit from self-measurement for guiding the treatment of patients with severe hypertension; they also separate groups of children with a positive vs. negative family history of high blood pressure, despite the difficulty of obtaining valid readings during the rest/sleep span, which are needed for a reliable estimation of the circadian parameters. From the viewpoint of preventive maintenance, a 67-year-old woman monitored her blood pressure and heart rate around the clock for 7 days, using concomitantly an ambulatory monitor and a manual instrument. Self-measurement profiles were repeated on several occasions. The results are compared with those of a 62-year-old woman who followed the same initial 7-day protocol. The estimation of the circadian blood pressure pattern differed between the profiles obtained with an ambulatory monitor and by self-measurement. The differences, relatively small in one subject, were much larger for the other subject. Provided the results are chronobiologically analyzed and interpreted in the light of reference limits which are specific to self-measurement series as well as for gender, age and times of sampling, systematic self-measurement of blood pressure may yield a reliable assessment of the circadian variation for some, but not for all, individuals. For those who have been validated in at least one 7-day/24-h profile, occasional automatic ambulatory profiles are tentatively recommended as the main approach, with complementary systematic self-measurement when automatic instruments are scarce. For those with discrepant results, automatic monitoring is invariably recommended.

Aged↗
PubMed2002

New insights into circadian aspects of health and disease.

Early awakening and early to bed as well as good conduct, thought, diet, interpersonal dealings and physical activity have been suggested for healthy life in Ayurveda. Circadian rhythms, coordinated in part by the parietal hypothalamic-pituitary and adrenal mechanisms, have been reported in almost all variables examined thus far, including the circulation. It is possible that all metabolic functions undergo circadian rhythms. It remains to be explored whether these rhythms may be optimized by Ayurvedic practices. The onsets of myocardial ischemia, unstable angina, acute myocardial infarction, sudden cardiac death, and strokes have been reported to exhibit a circadian variation, with increased frequency in the second quarter of the day. An increased physical and mental load caused by an attempt to prepare for the day may be important in triggering acute cardiovascular events. Depending on their timing, meditation (Ayurvedic practice), n-3 fatty acids, coenzyme Q10, beta-blockers and estrogens may have beneficial effects, whereas progestins and mental load may have adverse effects on heart rate and blood pressure variability, which may be expressed by different circadian patterns. Around the clock serial recordings of blood pressure and heart rate during usual activities and lifestyles may be recorded and may be analyzed by computer-implemented curve fitting to assess the about 24-hour (circadian) variation, among other rhythmic, chaotic, and trend components of the time structure (chronome) of these variables. The new disease risk syndrome circadian hyper-amplitude-tension (CHAT), a condition characterized by an excessive circadian amplitude of blood pressure, cannot be ascertained on the basis of single casual blood pressure measurements. The International Chronome Ecological Study of Heart Rate (and blood pressure) Variability in various ethnic groups aims at collecting further evidence regarding the role of blood pressure and heart rate variability in the pathogenesis of cardiovascular events, while also examining any role played by ethnicity and lifestyle-associated factors.

Blood Pressure↗
PubMed2001

Natural environmental associations in a 50-day human electrocardiogram.

Meteorotropic associations of heart rate (HR) and HR variability (HRV) were investigated in a clinically healthy 48-year-old man in Kiev. His electrocardiogram (ECG) was determined over 50 days by fitting him with an ambulatorily wearable device; various natural physical environmental variables were also monitored. The mean inter-beat interval, the standard deviation of these intervals, the spectral power in several frequency ranges, the power ratio of the approx. 10.5-s/approx. 3.6-s spectral components and other aspects of HRV were computed over consecutive 14.4-min intervals. Together with ordinary meteorological variables, geomagnetic disturbances (GMD) and fluctuations of atmospheric pressure (FAP) in the range 0.01-0.10 Hz (10-100 s) were measured. The assessable infradian spectra (with frequencies lower than 1 cycle/28 hours) of all HRV parameters showed two major components with periods of about 3.5 and 10 days. Two environmental variables, FAP and wind speed (with which FAP is closely related), revealed both of these rhythms and showed the greatest cross-spectral coherence (0.70-0.98) with corresponding oscillations of HRV. Less specific but statistically significant product-moment correlations with major HRV indices were also found; most of these were with FAP, but correlations with air temperature, humidity, wind speed and geomagnetic disturbances were also found. Long-term ECG recording, essential in the detection of infradian rhythms, proved to be sensitive to physical environmental variables, notably meteorological ones. FAP, usually neglected since its role has not been considered in previous biometeorological studies, or some factor closely related to FAP is probably involved in synchronizing or influencing the approximately 3.5-day HR and HRV rhythms in humans.

Analysis of Variance↗
PubMed2001

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.

Animals↗
PubMed2001

The week, inherited in neonatal human twins, found also in geomagnetic pulsations in isolated Antarctica.

About 7-day (circaseptan) components, found at different levels of organization, notably in relation to growth, regeneration, repair and development, are often viewed as reflecting no more than the 7-day societal schedule, ample evidence for a built-in feature notwithstanding. Herein, we resolve circaseptans in geomagnetic pulsations recorded by a stand-alone magnetometer residing in Antarctica, far away from societal influences. Human physiological data, collected in the neonatal intensive care unit, show by intra-class correlation analysis that the nonlinearly assessed circaseptan period of heart rate, diastolic blood pressure and body weight is more similar between same-gender twins than among twin pairs, lending additional support for the endogenicity of circaseptans. Like circadians, about-weekly features in environmental variables such as geomagnetic pulsations were genetically acquired in the course of evolution.

Activity Cycles↗
PubMed2001

Geomagnetic disturbance associated with decrease in heart rate variability in a subarctic area.

BACKGROUND: Physical environmental variables, such as the natural variation in the geomagnetic field in and around the earth, influence biological processes and human health. The effect of geomagnetic disturbances on heart rate variability (HRV) in healthy students in a subarctic area is studied herein. SUBJECTS AND METHODS: Seven-day records by Holter ECG were obtained from eight clinically healthy subjects in Alta, Norway (70 N). Frequency- and time-domain measures of HRV were compared between 24-hour spans of high geomagnetic disturbance versus quiet conditions. RESULTS: A 5.9% increase in the 24-hour average of HR (P = 0.020) and a 25.2% decrease in HRV (P = 0.002) were documented on days of high geomagnetic disturbance. The decrease in spectral power was found primarily at frequencies lower than 0.04 Hz and was not statistically significant around 3.6 sec. CONCLUSIONS: The physiological mechanism involved may be other than the parasympathetic, usually identified with spectral power centered around 3.6 sec, a spectral region wherein no statistically significant differences were found.

Adult↗
PubMed2001

Alternating light-darkness-influenced human electrocardiographic magnetoreception in association with geomagnetic pulsations.

Geomagnetic variations of partly interplanetary origin, with cyclic signatures in human affairs and pathology include the incidence of various diseases, regarding which this study of healthy subjects attempted to determine an underlying mechanism by worldwide archival and physiological monitoring, notably of heart rate variability (HRV). In the past half-century, the possible health and other hazards of natural, solar variability-driven temporal variations in the earth's magnetic field have become a controversial subject in view of the inconsistent results. Some well-documented claims of associations between geomagnetic storms and myocardial infarction or stroke have been rejected by a study based on more comprehensive data analyzed by rigorous methods - covering, however, only part of a solar cycle in only part of a hemisphere. It seems possible that inter-solar cycle and geographic variability, if not geographic differences, may account for discrepancies. Herein, we examine the start of a planetary study on any influence of geomagnetic disturbances that are most pronounced in the auroral oval, on human HRV. The magnetic field variations exhibit complex spectra and include the frequency band between 0.001-10 Hz, which is regarded as ultra-low frequency by physicists. Since the 'ultra-low-frequency' range, like other endpoints used in cardiology, refers to much higher frequencies than the about-yearly changes that are here shown to play a role in environmental-organismic interactions revealed by HRV, the current designations used in cardiology are all placed in quotation marks to indicate the need for possible revision. Whether or not this suggestion has an immediate response, we have pointed to a need for the development of instrumentation and software that renders the assessment of circadian, infradian and even infra-annual (truly low frequency) modulations routinely feasible. HRV was examined on the basis of nearly continuous 7-day records by ECG between December 10, 1998, and November 2, 2000, on 19 clinically healthy subjects, 21 to 54 years of age, in Alta, Norway. A geomagnetic record was obtained from the Auroral Observatory of the University of Tromsø. First, frequency-domain measures of HRV were compared for each person in 24-hour spans of high geomagnetic disturbance versus quiet conditions. Second, cross-spectra between geomagnetic activity and HRV measures were quantified via the squared coherence spectrum using 7-day time series. A 7.5% increase in the 24-hour average of heart rate, HR (P = 0.00020) and a decrease in HRV were documented on days of high geomagnetic disturbance. The decrease in HRV was validated statistically for the 'total frequency', 'TF' endpoint (18.6% decrease, P= 0.00009). The decrease in spectral power was found primarily in the 'circaminutan frequency', 'VLF' (21.9% decrease, P< 0.000001) in conjunction with the 'minutes-to-hours' component, ultra-low-frequency, 'ULF' (15.5% decrease, P= 0.00865) and circadecasecundan 'low frequency', 'LF' (14.2% decrease, P = 0.00187) regions of the spectrum. Power-law scaling of the power spectra did not show any statistically significant difference. It is noteworthy that most of the decrease in HRV, except for the circaminutan (VLF) component, was observed only in the season in which sunshine alternated with darkness (D/L), a finding suggesting a mechanism influenced by the alternation of light and darkness. The hypothesis of a light-dark-influenced magnetoreception was also supported by cross-spectral analysis. Group-averaged coherence at frequencies coincident with the geomagnetic Pc 6 pulsations (with periods ranging from 10 minutes to 5 hours) differed with a statistical significance (P < 0.000001) among the three natural lighting conditions, the association being weaker during UL or D/D than during D/L. By contrast, no statistically significant differences were found in terms of the circadian and circasemidian frequencies in relation to the alternation of sunshine with darkness or rather circannual rhythm stage. In conclusion, evidence is provided herein that an alteration of HRV is most apparent in the circaminutan ('VLF') region, which is clinically important, because a reduction in its power is a predictor of morbidity and mortality from cardiovascular disease. The circadecasecundan ('LF') component of HRV also decreased in association with geomagnetic disturbance, which may reflect an episodic alteration of arterial pressure related to changes in geomagnetic activity. Lastly, our study suggests the existence of a light-dark-influenced magnetoreception mechanism in humans involving mainly the Pc 6 band of the magnetic field.

Adult↗
PubMed2001

Associations by signatures and coherences between the human circulation and helio- and geomagnetic activity.

Helio-geomagnetic influences on the human circulation are investigated on the basis of an 11-year-long record from a clinically healthy cardiologist, 35 years of age at the start of monitoring. He measured his blood pressure and heart rate around the clock with an ambulatory monitor programmed to inflate an arm cuff, mostly at intervals of 15-30 minutes, with only few interruptions, starting in August 1987. While monitoring is continuing, data collected up to July 1998 are analyzed herein by cosinor rhythmometry and cross-spectral coherence with matching records of solar activity, gauged by Wolf numbers (WN) and of the geomagnetic disturbance index, Kp. A direct association between heart rate (HR) and WN is found to be solar cycle stage-dependent, whereas an inverse relationship between heart rate variability (HRV) and WN is found consistently. An inverse relation is also observed between WN and the variability in systolic blood pressure (SBP), and to a lesser extent, diastolic blood pressure (DBP). Moreover, HR is cross-spectrally coherent with WN at a frequency of one cycle in about 7.33 months. The results support previously reported associations on morbidity and mortality statistics, extending their scope to human physiology monitored longitudinally.

Adult↗
PubMed2001

Infradian, notably circaseptan testable feedsidewards among chronomes of the ECG and air temperature and pressure.

To study the interactions among the natural physical environmental cycles and human infradian components of heart rate (HR) and HR variability (HRV), a healthy 49-year-old man in Kiev, who had monitored his electrocardiogram (ECG) around the clock earlier for 50 days, added at a later date with the same ambulatorily wearable device, a record of 70 days. The mean value of the R-R intervals (R-R), their standard deviation (SDNN) and other HRV endpoints, computed over consecutive 5-min intervals, served as markers of the subject's functional associations with the amplitude of fluctuations in atmospheric pressure (FAP) and the planetary Kp index of geomagnetic disturbance. About-weekly and half-weekly cycles in HRV endpoints indicate a reduction in physiological 'preparedness', here described as 'dynamics', of the subject investigated on Saturdays and Sundays and a sharp increase in 'dynamics' on Mondays. The waveform of the weekly oscillation seemed to be influenced by ambient air temperature and FAP. On Mondays, an FAP amplification or a temperature rise was accompanied by a significant decrease in R-R and SDNN, indicating an aggravation of a 'Monday effect' in physiological 'dynamics'. HRV endpoints also revealed about-5-day and about-12-day cyclic components similar to those found in FAP. The infradian pattern in a 70-day record differed from one found earlier in a 50-day record of the same subject. Changes in the natural physical environment (past as well as present), especially in air temperature and FAP, likely influence(d) if not synchronize(d) the amplitude and waveform of infradian weekly and half-weekly physiological cycles. Some of these infradians, their wobbly nature notwithstanding, may have been built into our temporal make-up by an evolutionary integration of life in the non-stationary quasi-periodic natural physical environment, which continues to contribute to variability.

Air Pressure↗
PubMed2001

Circadian and infradian rhythms in mood.

The aim of this study was to assess any variation in positive, negative and total affect recorded longitudinally; to compare the results with those from prior transverse or hybrid population studies, based on the same or a different method of mood rating; and to test for any association of mood with cardiovascular, hormonal and geophysical variables monitored concomitantly. The study approach was as follows. A clinically healthy 34-year-old man filled out the positive and negative affective scale (PANAS) questionnaire five times a day for 86 days. Systolic (S) and diastolic (D) blood pressure (BP) and heart rate (HR) were also measured automatically at 30-minute intervals with an ambulatory monitor from May 19 to June 29, 2000, while different endpoints of heart rate variability (HRV) were also determined at 5-minute intervals from beat-to-beat electrocardiogram (ECG) monitoring for 42 days between May 3 and June 14, 2000, with only short interruptions while the subject took a shower and changed ECG tapes. Saliva samples were collected at the times of mood ratings for one month for later determination of melatonin and cortisol concentrations. Intervals of 24 hours of the record of each variable displaced in increments of 24 hours were analyzed by chronobiologic serial section at a trial period of 24 hours to assess the circadian characteristics as they changed from one day to another. Estimates of the midline-estimating statistic of rhythm (MESOR) and circadian amplitude and acrophase obtained on consecutive days were correlated among variables to assess any associations. The findings were as follows. Overall, a circadian rhythm was demonstrated for all variables. A positive association was noteworthy between the circadian amplitude of negative affect and the MESOR of both SBP (r= 0.363; P= 0.029) and DBP (r= 0.389; P= 0.019), suggesting that BP is raised in the presence of large swings in negative affect. Needing further validation was a weak association between the MESOR of negative affect and the circadian amplitude of SBP (r= - 0.272; P = 0.108), suggesting a lowering of the circadian SBP amplitude in the presence of a strong negative affect. Of further interest was the lack of a statistically significant relation between positive and negative affect, not only in terms of the MESOR but also in terms of the circadian amplitude.

Adult↗
PubMed2001

Impact of circadian amplitude and chronotherapy: relevance to prevention and treatment of stroke.

The long-acting calcium antagonist nifedipine reduces the incidence of stroke in Eastern Asia, as shown by the Shanghai Trial Of Nifedipine in the Elderly (STONE) and the Systolic Hypertension in China (Syst-China) trials. Recent trials in Japan have shown that benidipine may be more efficient than the former drug in preventing strokes in the elderly. Benidipine, commonly prescribed in Japan for a definite depressor effect, reportedly without causing remarkable fluctuations in blood pressure (BP), is investigated herein from a chronobiological viewpoint. Eighteen subjects (nine women and nine men, 39 to 87 years of age) with essential hypertension (office and ambulatory systolic, S/diastolic, D BP values above 160/95 mm Hg and 130/80 mm Hg, respectively) were enrolled in this investigation. Ambulatory BP was monitored at 30-min intervals for at least 24 h (ABPM-630, Colin Medical) before and after 4 weeks of crossover treatment with nifedipine tablets (twice daily, 20 mg/d) and benidipine (once daily, 4 mg/d, in the morning). The results indicate that: 1) benidipine and nifedipine reduce 24-h daytime (10:00-20:00) and nighttime (00:00-06:00) averages of SBP and DBP (P < 0.001); 2) the circadian double amplitude of BP is decreased after treatment with benidipine (from 28.6 to 21.1 mm Hg SBP and from 19.7 to 15.2 mm Hg DBP; P< 0.05), while the day-night difference in SBP is increased after treatment with nifedipine (18.6 vs 27.9 mm Hg, P< 0.01); and 3) the increase in the day-night difference of heart rate (HR) is significant after treatment with benidipine (13.6 vs 18.8 beats per minute, bpm; P< 0.05), but not with nifedipine. We have previously evaluated the usefulness of the circadian amplitude of BP as a prognostic tool of cardiovascular outcome, and found that an excessive circadian SBP or DBP amplitude was associated with an increased risk of vascular disease. The fact that benidipine reduces the circadian BP amplitude may be one reason for the superiority of this treatment over nifedipine in preventing an adverse outcome. A reduced heart rate variability (HRV) also predicts adverse cardiovascular outcomes in patients with overt cardiovascular disease and in hypertensive subjects. The fact that benidipine increases the day-night difference in HR may be another reason for the positive effects of this treatment.

Adult↗
PubMed2001

Relationship between correlation dimension and indices of linear analysis in both respiratory movement and electroencephalogram.

OBJECTIVE: We investigate the relationships between signals from the electroencephalogram (EEG) and those from respiratory movement using the correlation dimension (D(2)). METHODS: Respiratory movement and EEG were recorded for 7.5h from 7 clinically healthy men. D(2) was calculated by applying an algorithm slightly modified from that proposed by Grassberger and Procaccia (Phys Rev Lett 50 (1983) 346). Non-linearity in respiratory movement and EEG was tested by comparing D(2) for the original data with that for surrogate data. RESULTS: A statistically significant positive correlation between D(2) of the EEG and D(2) of the respiratory movement was observed for the original data, but not for the surrogate data. CONCLUSIONS: A reduced D(2) of the EEG may be associated with an increased regularity of breathing in deep sleep (stage IV). Likewise, the increased D(2) of respiratory movement during rapid eye movement may be associated with increased complexity of the signals. Whether there is a direct coordination between brain and lungs or whether brainstem systems, including that of the cholinergic system, affect both respiration and cortex requires further investigation.

Adult↗
PubMed2001

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.

Age Factors↗