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Biomedical subjects

F Halberg

Publications and source records attributed to F Halberg.

At least 109 records · Page 6Linked to original sources
PubMed1994

[Circadian profiles of blood pressure with respect to age].

UNLABELLED: The effects of ageing on nocturnal blood pressure (BP) and the circadian rhythm of BP were studied. Ambulatory BP and heart rate (HR) were monitored at 30-minute intervals for 24 hours, in 326 normotensive volunteers aged 15-83. The following groups were monitored: young: < 40 yrs, n = 177; middle: 40 yrs < or = - < 60 years, n = 100; old: 60 yrs < or =, n = 49 Firstly, the ratio of nocturnal fall (RONF) of BP (or HR) was calculated as follows: [(average day time BP (or HR)-average night time BR (or HR)]/averaged whole day BP (or HR) x 100. Then we calculated 2 measurements: 1. The dipper (RONF of BP (or HR) > or = 10% 2. The non-dipper. (RONF of BP (or HR) < 10%. A cosine fitting technique using the least-squares method was employed to find the circadian rhythm of BP and HR. The results of the study showed that the incidence of the non-dipper on systolic BP (SBP) was higher for old subjects than for young subjects. In addition, the nocturnal BP and HR were higher for old subjects than for young subjects. The circadian amplitude of HR was lower in old subjects. The circadian midline estimating statistic of rhythm (MESOR) or SBP increased with age. The circadian acrophase of BP and HR increased with age. CONCLUSION: non-dippers of BP and HR were observed in any age groups. The frequency of BP and HR non-dipper was greater for old subjects than young subjects. This result may suggest the clinical significance of nocturnal BP and HR for the evaluation of hypertensive subjects.

Adolescent↗
PubMed1994

From circadians of the fifties to chronomes in vitro as in vivo.

In a recent review of cellular mechanisms of entrainment, an ocular circadian rhythm of Bulla was reported (1). The isolated retina of this marine mollusk is described to contain a circadian oscillator. A glance at the spontaneous impulse frequency from eyes recorded in darkness at 15 degrees C suggests lower-frequency modulations of the about 24-h rhythm and prompts the quantitative assessment of the broader time structure, the chronome, in this extensively used model of a budding neurochronophysiology. The cultured retina of mollusks is interpreted by the original authors as descriptive of similar cellular mechanisms that may underlie mammalian as well as molluscan physiology. We report here the rhythmometric analysis of the original data by Block et al. (2), taken from Figure 2 of the article by Colwell et al. (1), resolved by computer just as the microscope resolves cellular structure. The results are further compared with those obtained on data kindly provided by Stephan Michel on another retina of Bulla. The findings of multiple chronome components (beyond the circadian system) are placed into the broader context of cell biophysics and its implications for biomedicine within the scope of an international chronome endeavor.

Action Potentials↗
PubMed1994

Circadian profiles of blood pressure and heart rate of apparently healthy metropolitan Japanese.

The circadian waveform in blood pressure (BP) and heart rate (HR) was explored in metropolitan Japanese. Clinically healthy subjects (50 women and 50 men, aged 40-59 years) were selected for the study of computing a peer-group reference standard. Hypertensive subjects diagnosed by conventional criteria (systolic(S)BP/diastolic(D)BP > or = 160/90 mmHg) also volunteered for this study. Each was to provide measurements of SBP, DBP, and HR at 15 min intervals over 48 h by using an ambulatory monitor ABPM-630 (Colin Medical, Komaki, Japan). Reference limits were computed as 90% prediction limits specified by the circadian stage. Data in intervals of 30 min, displaced by 15 min, were used for the computation of these limits. Those time-qualified reference limits were reconstructed as 'three-component chronodesms' with the two harmonics (12 h and 8 h) in conjunction with the fundamental period (24 h). The coefficient of harmonics needed was determined by discrete Fourier transform (DFT). A diagnosis based on office BP readings was confirmed chronobiologically. As a result, the circadian BP profiles did not exceed the upper limit in 27/107 hypertensives for SBP and in 30/107 hypertensives for DBP. In conclusion, chronobiologic approaches improve the sensitivity and the reliability of diagnosis.

Adult↗
PubMed1994

Chronobioengineering toward a cost-effective quality health care.

The current disease-cure-oriented health care system does too little too late for too few. Engineering for concomitantly resolving the external conditions and the internal schedules, chronoengineering in the broad sense, could change this status quo into a system that recognizes environmental and organismic risk early, blows a whistle as a minimum and acts automatically, as an optimum. The chronobioengineering feature (of the broader chronoengineering for external as well as internal monitoring and decision helping) would gain new individualized information from the resolution of predictable variations that occur within the physiologic range, the chronomes, genetically anchored multifrequency rhythms and trends. Their resolution by chronobiometry provides a more precise and more accurate mean value (than the arithmetic mean) along with new dynamic endpoints for improved screening, diagnosis, prognosis, and timely and timed treatment. Trends are those with growth, development, maturation and aging, and also those with risk elevation or disease and treatment. Risk elevation may change amplitude or timing, but not necessarily the mean. The implementation of engineering for concomitantly resolving the external and internal schedules depends on telecommunications and telehygiene as well as telemedicine for (i) universal chronobiologic education (to assume self-responsibility and self-help in health care), (ii) physiologic monitoring (complemented as a sine qua non by chronobiologic data analysis and interpretation of the results) and (iii) the monitoring of pertinent environmental conditions. Thus, the number of cases of catastrophic diseases could be reduced and quality (since preventive) health care made available to all.

Adult↗
PubMed1993

Doppler flowmeter-assessed circadian rhythms in neonatal cardiac function, family history, and intrauterine growth retardation.

This study examines the circadian variation of aortic blood flow velocity, acceleration, and distance of stroke, assessed every 4 hours for 24 hours by Doppler ultrasound in 88 human newborns. Groups 1 and 2 involve neonates with a negative family history of high blood pressure or myocardial infarction monitored during the first day or between the second and tenth days postpartum, respectively; groups 3 to 6 are 2- to 10-day-old babies with a positive family history of high blood pressure (group 3) or of myocardial infarction (group 4) or with a negative family history and intrauterine growth retardation (group 5) or born prematurely (group 6). Cosinor analyses demonstrate a circadian rhythm for all variables in groups 2 and 5 (p < 0.001), with overall high values occurring around 17:40. In group 2, a circadian rhythm remains demonstrable in boys and girls considered separately, and mostly so in arbitrary subgroups of different sizes, with only slight differences in rhythm parameters among them. These results show that, with relatively small samples, reproducible circadian rhythms of cardiac function can be detected shortly after birth in neonates with a negative family history of high blood pressure or myocardial infarction.

Analysis of Variance↗
PubMed1993

Rhythms and blood pressure.

The time (chronos) structure of life (bios) is the topic of a computer-implemented science (logos), chronobiology. Chronobiologic methods for resolving physiologic time structure provide a more reliable mean, the MESOR, and other parametric dynamic measures of blood pressure variability. The amplitude is a measure of predictable extent of change and the acrophase a measure of timing of overall high values within each cycle of the rhythmic function. Such chronobiologic endpoints are often more sensitive than the mean for separating groups at different risk of developing high blood pressure. About 24-h (circadian) rhythms account for a sizeable part of predictable variability in blood pressure. Methodology to assess the characteristics of circadian blood pressure rhythms also provides time-varying reference limits for the interpretation of single measurements. Deviant blood pressures can be quantified by reference to such circadian-stage-dependent limits, derived from the automatically monitored blood pressure profiles of healthy peer groups. Excess or deficit in blood pressure can also be assessed as a hypertensive or hypotensive index integrated over 24 h. Chronobiologic monitoring has wide uses in practice as well as research, whether it is carried out by self- or automatic measurements, once the data are analyzed by appropriate computer methods that are now readily available.

Adult↗
PubMed1993

[Monotonous and wave-form changes in the myelogram of rats over a 24-hour period].

Circadian changes of the mean value of each component of rat myelogram and of the proliferative pool of bone marrow cells were obtained. These changes were imposed on a monotonous decrease in the case of subpopulations of granulocytes or on a monotonous increase in the case of subpopulations of the erythroid cells and lymphocytes (from 12.00 to 09.00 next day). This process was not influenced by the elimination of the lymphocytes from the individual myelograms. These myelogram changes appeared to be due to the circadian mature cell production rhythm and flows of the lymphocytes and of mature granulocytes between the bone marrow and the peripheral blood. These changes also suggest the antiphase monotonous correction of the erythrocytic and granulocytic precursors production during several days.

Animals↗
PubMed1993

[24-hour monitoring of blood pressure in patients with essential hypertension].

The aim of the study was to determine the efficiency of enalapril therapy during 24-hours blood pressure monitoring. A group of healthy subjects (C, n = 11), a group of patients with essential hypertension without therapy (EH, n = 9) and a group of patients with essential hypertension II (WHO) treated with enalapril (Acepril Lachema) in once a day doses (13.0 +/- 2.1 mg per kg) during at least 10 months (EH A, n = 8). In all groups of patients and healthy subjects 24-hours blood pressure measurement was provided using Accutracker II equipment. The mean values of systolic (SBP) and diastolic blood pressure (DBP) from 24-hours measurement (+/- SD) were in the group of healthy subjects C 121.38 +/- 10.49/74.79 +/- 7.88 mmHg, in the group EH 146.58 +/- 12.20/88.0 +/- 8.97 mmHg, in the group EH A 127.38 +/- 8.36/74.71 +/- 6.08 mmHg. The differences between the maximum and minimum mean blood pressure values during 24 hours (SBP/DBP) were in the group C 33/27 mmHg, EH 37/29 mmHg, EH A 29/21 mmHg. The smaller difference in SBP and DBP in EH A patients was significant in comparison to C and EH (t-test, p < 0.05). Cosinor analysis proved the results. From our results we can conclude that the Acepril therapy decreases blood pressure more during the day-hours then during night and it is preferable in connection to the risk of night hypotension with hypoxia.

Blood Pressure↗
PubMed1992

Surgical influence on murine immunity and tumor growth: relationship of body temperature and hormones with splenocytes.

Adrenalectomy predisposed the C3HeB/FeJ Mouse to tumor from a low dose of tumor cells, derived from a C3H spontaneous mammary adenocarcinoma. Sham surgery had a similar effect. In contrast, ovariectomized females, intact females, and male mice did not allow the low dose of cells to develop into a tumor. In order to better understand the role of hormones on the immune system controlling tumor growth, normal C3HeB/FeJ mice were studied for the effect of corticosterone or estradiol on splenic lymphocyte surface antigen expression. Adrenalectomy and ovariectomy caused a decrease in the percentage of all T cell subclasses and an increase in absolute numbers of immunoglobulin-bearing cells. Reconstitution of ovariectomized mice with estradiol did not significantly alter lymphocyte cell surface antigen expression. In contrast, injection of corticosterone into adrenalectomized mice brought these values to normal. Further study on normal mice placed on a 12:12-hr light:dark schedule showed that the hours after lights on (HALO) had a significant effect (analysis of variance) on body temperature, percentage of splenic B cells, T pan, T helper and T suppressor cells, and absolute numbers of T pan cells. Brain dehydroepiandrosterone sulfate correlated positively with T pan lymphocytes, but showed no significant effect on HALO. In contrast, body temperature showed a strong circadian rhythm (P less than 0.001). In addition, the presentation of estrus was circadian rhythmic (P = 0.003) with 58% of mice in estrus at 16 HALO and only 8% at 4 HALO. Multiple regression analysis revealed body temperature was strongly associated with absolute numbers of splenic T lymphocytes and their subsets, as well as percentage of B lymphocytes, Thy 1.2-, and Lyt-2-bearing cells. Similarly, HALO and estrous cycle stage were associated with percentage of T helper cells. The data showed that body temperature and hormones were associated with the cell surface antigens on lymphocytes and suggest that they affect lymphocyte function.

Adenocarcinoma↗
PubMed1991

Cognitive function in children with leukemia. Effect of radiation dose and time since irradiation.

The effect of two cranial radiation (CRTX) doses and the time since radiation therapy on cognitive functioning were studied in 35 children who completed therapy for acute lymphoblastic leukemia (ALL). The patients were grouped according to CRTX dose (2400 or 1800 cGy) and evaluated for general intelligence, academic achievement, and visual motor integration. Those who received 2400 cGy (n = 20) scored ten points below those treated with 1800 cGy (n = 15) on verbal intelligence quotient and achievement tests of reading, spelling, and arithmetic. The effect of time since radiation therapy on these measures of cognitive function was significant (P = 0.001 to 0.03); the effect of CRTX dose was not. Visual motor integration scores in both groups fell below the 33rd percentile. The effect of CRTX dose and time since radiation therapy on visual motor integration and performance intelligence quotient were not significant. Thus, the interval between treatment and the emergence of cognitive impairments may be longer after lower CRTX doses, and deficits in nonverbal areas such as visual motor integration may appear first. A larger study is needed to confirm these findings from a limited sample of long-term survivors of ALL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Time-varying limits for single blood pressures and heart rates of group-synchronized healthy women.

The circadian waveform in blood pressure (BP) and heart rate (HR) was explored in young adult women. Clinically healthy nurses, 18-25 years of age, volunteered for this study. Each was to provide measurements of systolic, mean arterial, and diasolic BP and HR at 15-min intervals over 48 h by using an ambulatory monitor ABPM-630 (Colin Medical, Komaki, Japan). The data consist of several sets of values. One set consists of a series from each of 44 student nurses, monitored in November, 1987. A second set stems from 50 nurses studied in June, 1988. Another set is composed of data from 56 nurses monitored between May and September, 1989. The nurses were all on a diurnal activity/nocturnal rest schedule. Reference limits were computed as 90% prediction limits specified by circadian stage. Data in intervals of 1 h, displaced by 30 min were used for the computation of these limits. Examination of chronodesms, i.e., time-specified limits of acceptability, revealed that the limits were very rugged. Similar features were found for all sets of data, such as peaks after arising, around noon, and in the evening. The features may perhaps be related to a physiologic response rather than representing purely random variation.

Adolescent↗
PubMed1991

Chronobiologic approach to beat-to-beat variations of cultured murine myocardial cells.

An earlier demonstration of a circadian rhythm in rat atria by others is complemented herein by observations in culture: A single murine myocardial cell and two sets of grouped cells beating in culture for several days reveal several features of an anticipated, presumably built-in spectrum of multifrequency rhythms and trends, the chronome. Circadian and about 12-h (circasemidian) components are modulated by an approximately 84-h (circasemiseptan) component, which cannot be separated from trends in view of the brevity of the series. The circumstance under which the culture is aging and in which fibroblasts proliferate is a further complication that limits the findings to a single cycle reproduced in three separate cultures. Whether it is a rhythm that repeats itself of a response to placement into culture, an approximately 3.5-d component in the beating of myocardial cells in culture is to be aligned with a very prominent similar component found in the incidence of 85,819 human myocardial infarctions.

Animals↗
PubMed1991

Circadian variation in the gastric-emptying response to eating in rats previously fed once or twice daily.

Four experiments dealt with circadian variation in the gastric emptying (GE) response to eating, among rats accustomed to eating once (1x) or twice daily (2x). In measuring GE response, a test meal [10 g accustomed diet per (kg body weight)3/4] was fed close to a scheduled eating time or after a delay of up to 24 h. GE response was the fraction of the ingested test meal emptied per hr, up to a known degree of emptying, e.g., 50-58% of the test meal. Animals accustomed to the prescribed eating patterns ate promptly and at similarly rapid rates at all times of day. GE response, as plotted against time of response, fit a 24-h cosine model. Acrophase (time of maximum GE response of the fitted model) was similar, being 1.5 and 2.1 h, respectively, after the starting time of the accustomed dark-span meal for 1x and 2x rats, while amplitude (1/2 the maximum-to-minimum difference) was 41 and 24% of the MESOR (rhythm-adjusted mean). Characteristics of the GE rhythm appeared to be unchanged among 1x rats, severely versus minimally restricted in food intake during a final 9 days.

Animals↗