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PubMed1994

Defining rhythm: aspects of an anthropology of rhythm.

This paper outlines the relevance of the idea of rhythm to cultural anthropology, with specific suggestions for a medical anthropology of rhythm. By reconsidering the fluid nature of the concept of rhythm in ordinary language, the paper defines rhythm functionally in terms of a temporal order that anticipates, suspends and fulfills on the level of the visceral, physical, ecological, institutional as well as the moral. Although the paper identifies most explicitly the link between the bodily and social rhythm, it tries to suggest a cosmic background in the interaction of the social and bodily rhythms. The paper is divided into three parts: 1) the general problem of defining rhythm, 2) the concept of rhythm from its origin, and 3) the concept of rhythm in cultural theory since Durkheim. Further readings in particular reference to medical anthropology are often indicated in the notes.

Anthropology, Cultural↗

PubMed2005

Functional status in rate- versus rhythm-control strategies for atrial fibrillation: results of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) Functional Status Substudy.

OBJECTIVES: The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) functional status substudy aimed to test the hypothesis that functional status is similar in rate-control and rhythm-control strategies. BACKGROUND: Randomized studies, including the AFFIRM study, have failed to demonstrate survival benefits between rate-control and rhythm-control strategies for atrial fibrillation (AF). However, AF may cause functional capacity or cognitive impairment that might justify maintenance of sinus rhythm. METHODS: Investigators of the AFFIRM study enrolled 4,060 patients with AF who required long-term therapy and who were 65 years of age or older or who had another risk factor for stroke or death. New York Heart Association functional class (NYHA-FC) and Canadian Cardiovascular Society Angina Classification were assessed at initial and each follow-up visit. From 22 randomly chosen functional status substudy sites, 245 participants underwent 6-min walk tests and Mini-Mental State Examination (MMSE) at initial, two-month, and yearly visits. Patients were assigned randomly to rate-controlling drugs, allowing AF to persist, or rhythm-controlling antiarrhythmic drugs, to maintain sinus rhythm. RESULTS: The NYHA-FC worsened with time in both rate-control and rhythm-control groups, with no differences between groups. Presence of AF was associated with worse NYHA-FC (p < 0.0001). No differences were observed in Canadian Cardiovascular Society Angina Classification or MMSE scores. Six-minute walk distance improved over time in both study arms. On average, walk distance was 94 feet greater in the rhythm-control group (adjusted p = 0.049). CONCLUSIONS: Modest improvement in 6-min walk distance was noted in the rhythm-control arm. Presence of AF was associated with worse NYHA-FC. No difference in cognitive function was detected.

Aged↗

PubMed2002

The development of infants' circadian rest-activity rhythm and mothers' rhythm.

In order to know when and how infants obtain their circadian sleep-wake rhythm, infants' developing circadian rest-activity rhythm and mothers' circadian rhythm in the postpartum period were examined using actigraph monitoring. The subjects were 11 primipara and their infants. Actigraphic recordings for the infants and their mothers were made over 3-5 continuous days during the 3rd, 6th, 9th and 12th weeks after birth. A 24-h peak on a mean autocorrelogram of the infants' movements was detected at the 3rd week. The infants' circadian rest-activity rhythm already existed in the 3rd week. The amplitude of this 24-h peak gradually increased from the 6th to 12th week. This may be useful as an index of the development of infants' circadian rest-activity rhythm. An 11-h peak was also observed at the 3rd week. This 11-h peak was thought to be a semi-circadian rhythm. Regarding the mothers, the amplitude of the 24-h peak on the mean autocorrelogram at the 3rd week was the smallest of all other weeks, and it became larger from the 3rd to 12th week. This meant that the mothers' circadian rhythm at the 3rd week was influenced by their interrupted sleep at night to take care of their infants. The mother-infant synchronization is probably the 1st factor in the entrainment of infants' circadian sleep-wake rhythm. In this study, we also propose a novel method for compensating for missing data in autocorrelogram analysis.

Activity Cycles↗

PubMed1994

Frontal midline theta rhythm: differentiating the physiological theta rhythm from the abnormal discharge.

The theta rhythm that appears in the frontal midline was studied morphologically and clinically in EEGs performed on 788 patients and 161 normal subjects in their late teens or older. This theta rhythm was classified into 2 types. The Type 1 theta rhythm appeared in short bursts maximally in the Fz lead and spread mainly to the anterior region. It had a high frequency, low voltage and regular waveform. The Type 2 theta rhythm appeared in long runs maximally in the Fz lead and spread mainly to the posterior areas. It had a relatively low frequency, high voltage and irregular waveform. Type 1 was observed in a younger age group (mean age: 20.3 years) that was comprised of healthy subjects and one mentally retarded patient. In no case was the Type 1 theta rhythm accompanied by a paroxysmal EEG abnormality. We therefore believe that Type 1 is a physiological EEG activity (Fm theta). On the other hand, Type 2 was observed in a relatively older age group (mean age: 30.7 years) comprised of patients diagnosed as having epilepsy or intractable headaches. Five of 9 cases showed epileptic EEG abnormalities. We therefore believe that Type 2 might have clinical significance in diagnosis of epilepsy and other cerebral dysfunctions. The EEG pattern that we call the frontal mid-line theta rhythm may be either a physiological theta rhythm or an abnormal discharge. It is possible to determine whether the theta rhythm is the former or the latter, and we believe this differentiation to be clinically important.

Adolescent↗

PubMed2005

The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborn.

INTRODUCTION: The hormone melatonin regulates the sleep and this pineal hormone is synthesized in the organism from the amino acid tryptophan. It is known that breast-fed babies have better sleep patterns and a better entrained sleep/wake cycle than bottle-fed babies (adapted formula). OBJECTIVE: To compare the circadian rhythm of 6-sulfatoxymelatonin (aMT6s)--the metabolite of melatonin excreted in the urine--in urine of bottle-fed and breast-fed children, and relate it to the circadian rhythm of tryptophan in breast milk, also evaluating the possible effects on the baby's night-time rest. METHODS: 16 infants of 12 weeks of age were studied, divided into two groups depending on their exclusively natural or artificial feeding. The circadian rhythm of 6-sulfatoxymelatonin in urine was measured for the two groups of infants and for the breast-feeding mothers. In the breast milk, the circadian rhythm of the amino acid tryptophan was measured. The rest of the infants was tested by wrist actimeters for a week and the sleep parameters of the infants were measured and evaluated. RESULTS: The tryptophan in the breast milk presented a circadian rhythm with acrophase at around 03:00. This affected the 6-sulfatoxymelatonin circadian rhythm with acrophase at 06:00 in the breast-fed infants, and also promoted nocturnal sleep. Assumed sleep, actual sleep, and sleep efficiency were significantly increased in the breast fed infants with respect the formula fed infants. CONCLUSION: A temporal relationship was observed between the circadian rhythm of 6-sulfatoxymelatonin of the exclusively breast-fed babies and that of tryptophan in the mother's milk. Acting this amino acid as a zeitgeber entrainment of the biological rhythms in the breast-fed infant.

Bottle Feeding↗

PubMed1993

Chronopharmacology of psychotropic drugs: circadian rhythms in drug effects and its implications to rhythms in the brain.

The effects of many kinds of psychotropic drugs have been shown in animal studies to follow a circadian rhythm. Trials for the clinical application of this circadian rhythm have already been undertaken. Although the mechanisms underlying this phenomenon are still unclear, chronological changes in the levels of drugs in the blood and brain suggest that it is primarily due to rhythms in the brain's susceptibility to drugs. Rhythms are present in the level of intracerebral neurotransmitters, receptors and second messengers. Each of these rhythms may cause other rhythms within each system of neurotransmitters, which in turn induces a rhythm in the susceptibility to drugs.

Absorption↗

PubMedDate not supplied

New roles for the gamma rhythm: population tuning and preprocessing for the Beta rhythm.

Gamma (30-80 Hz) and beta (12-30 Hz) oscillations such as those displayed by in vitro hippocampal (CA1) slice preparations and by in vivo neocortical EEGs often occur successively, with a spontaneous transition between them. In the gamma rhythm, pyramidal cells fire together with the interneurons, while in the beta rhythm, pyramidal cells fire on a subset of cycles of the interneurons. It is shown that gamma and beta rhythms have different properties with respect to creation of cell assemblies. In the presence of heterogeneous inputs to the pyramidal cells, the gamma rhythm creates an assembly of firing pyramidal cells from cells whose drive exceeds a threshold. During the gamma to beta transition, a slow outward potassium current is activated, and as a result the cell assembly vanishes. The slow currents make each of the pyramidal cells fire with a beta rhythm, but the field potential of the network still displays a gamma rhythm. Hebbian changes of connections among the pyramidal cells give rise to a beta rhythm, and the cell assemblies are recovered with a temporal separation between cells firing in different cycles. We present experimental evidence showing that such a separation can occur in hippocampal slices.

Animals↗

PubMed1992

Seasonal variation in the human circadian rhythm: dissociation between sleep and temperature rhythm.

The circadian rhythms of sleep-wakefulness, rectal temperature, and plasma melatonin were measured in 10 healthy male subjects for five consecutive seasons. To minimize direct effects of seasonally changing environmental factors, the subjects stayed in a living facility for 4 days in each season, where ambient temperature, humidity, and social contacts were controlled, while the light intensity of the living room was substantially influenced by natural daylight. Seasonal variations were found in the timing of sleep, the mean body temperature, the phases of circadian temperature and melatonin rhythms, and the phase relation between sleep and the rectal temperature rhythm. The subjects went to bed earliest in summer, intermediate in spring and autumn, and latest in winter. A similar but more pronounced seasonality was observed in the wake-up time, which was earlier in summer than in winter. The acrophases of the rectal temperature and plasma melatonin rhythms, which were calculated by fitting a cosine curve, were located in an earlier time of day in summer than in winter. The phase-angle difference of the rectal temperature rhythm to sleep varied seasonally and was more positive in summer than in winter. These findings indicate that not only the external (to the local time) but also the internal (between circadian rhythms) phase relations of the human circadian rhythms depend on season.

Adult↗

PubMed1976

Entrainment of the adrenal rhythm to photoperiod prior to puberty: effects of early experience on the adrenal rhythm and puberty.

The purpose of this study was to determine whether exposure to a cycle of light and dark before the onset of the adrenal rhythm would be necessary in order for rats to develop a normal rhythm of peripheral corticosterone when placed in a test photoperiod at weaning age. Rats were reared in constant light (LL) until weaning age, at which time they were placed in a cycle of 14 h light, 10 h dark (14:10). Females born and reared in 14:10 had peak corticosterone values at 14.00 h on days 22 and 26, and at 18.00 h on days 32 and 36. Males did not display a clear-cut rhythm at 22 or 26 days but had peak corticosterone at 18.00 h on days 32 and 36. Males and females reared in LL until weaning had no rhythm as a group in 14:10 at 24 days of age, but had a corticosterone peak at 18.00 h on days 28 and 40. Females born and reared in LL and exposed to 14:10 for 1 day developed an adrenal rhythm regardless of the age at exposure, but only 25 day old animals showed a normal pattern for their age group. Puberty was advanced in rats exposed to a single day of 14:10 at 25 days of age, but was delayed in younger rats (22 days old), and was unaffected by light exposure in older rats (28 days of age). It can be concluded that early exposure to light-dark cycles is not required for the normal development of an adrenal rhythm in the weanling rat, and that the setting of the corticosterone rhythm to the photoperiod can occur quite rapidly. Rats at 25-26 days of age are able to respond differently to a light cycle challenge than younger rats. A photoperiodic stimulus at that time can advance the onset of puberty.

Adrenal Glands↗

PubMed2003

Rhythm-independent feature of heart rate dynamics common to atrial fibrillation and sinus rhythm in patients with paroxysmal atrial fibrillation.

OBJECTIVES: To examine if the long-range correlation in heart rate variability is a rhythm-independent characteristic common to both atrial fibrillation (AF) and sinus rhythm (SR) periods in patients with paroxysmal atrial fibrillation (PAF). METHODS: Holter electrocardiography was analyzed during sleep in 18 patients with paroxysmal atrial fibrillation during the atrial fibrillation (PAF-AF) and sinus rhythm (PAF-SR) periods, and also in 19 healthy controls with sinus rhythm (CTR-SR). The heart rate dynamics were assessed with the power-law spectral exponent (slope) of the log-log power spectrum between 0.0001 Hz and the breakpoint frequency. RESULTS: The slope showed a significant correlation between PAF-SR and PAF-AF (r = 0.614, p < 0.01). During sinus rhythm, the slope in paroxysmal atrial fibrillation with cardiovascular disease [PAF-SR (cvd+)] was steeper than that in paroxysmal atrial fibrillation without cardiovascular disease [PAF-SR (cvd-)] (p < 0.05). Although the slope was comparable between PAF-SR (cvd-) and CTR-SR, the slope in PAF-SR (cvd+) was steeper than that in CTR-SR (p < 0.05). A similar tendency was shown during atrial fibrillation. The slope in paroxysmal atrial fibrillation with cardiovascular disease [PAF-AF (cvd+)] was steeper than that in paroxysmal atrial fibrillation without cardiovascular disease [PAF-AF (cvd-)] (p < 0.05). Although the slope was comparable between PAF-AF (cvd-) and CTR-SR, the slope in PAF-AF (cvd+) tended to be steeper than that in CTR-SR. CONCLUSIONS: The long-range correlation in heart rate variability during sleep was a rhythm-independent characteristic and so may have a similar clinical value during atrial fibrillation and sinus rhythm in patients with paroxysmal atrial fibrillation.

Adult↗

PubMed1989

A circadian rhythm of aqueous flow underlies the circadian rhythm of IOP in NZW rabbits.

There is a daily rhythm of aqueous flow in New Zealand White rabbits entrained to 12 hr light:12 hr dark. The phase of the rhythm of flow is determined by the phase of the light:dark cycle, and the rhythm persists in constant dark. Therefore, in New Zealand White rabbits the rhythm of aqueous flow, like the rhythm of intraocular pressure, is circadian. The range of the circadian rhythm of flow suggests it plays a major role in producing the circadian rhythm of intraocular pressure. This animal model provides a powerful tool for studying endogenous mechanisms which regulate aqueous humor formation and intraocular pressure.

Animals↗

PubMed1999

Isolated chick sclera shows a circadian rhythm in proteoglycan synthesis perhaps associated with the rhythm in ocular elongation.

In the growing chick, ocular elongation is rhythmic, increasing during the day and decreasing at night. Because experimentally induced changes in the rate of ocular elongation are associated with changes in the rate of synthesis of scleral proteoglycans, we asked whether there is a diurnal rhythm in scleral proteoglycan synthesis, whether the rhythm is endogenous, and whether scleras from normal eyes differed from those of faster growing form-deprived eyes. To assess proteoglycan synthesis, we measured the incorporation of labeled sulfate into glycosaminoglycans using two paradigms: (1) punches of sclera were cultured for either 2 or 10 h at various times of day, and (2) punches were cultured in a perifusion system for up to 80 h, and samples of the medium were collected for analysis at 2-h intervals. Synthesis of scleral proteoglycans is higher during the day than during the night. This rhythm persists for at least three cycles in vitro with a period of approximately 24 h. There are no significant differences between rhythms in scleras from normal and form-deprived eyes. Finally, biochemical analyses show the labeled molecule to be similar to aggrecan, the cartilage proteoglycan. We conclude that the synthesis of proteoglycans by scleral chondrocytes is circadian, and we speculate that this rhythm may influence the rhythm in ocular elongation.

Animals↗

PubMed1990

Circadian rhythms in depression. Part II: Circadian rhythms in inpatients with various mental disorders.

We investigated longitudinally the circadian body temperature rhythms in 65 inpatients with various mental disorders, 38 of whom had major depressive episodes, by estimating the deep body temperature from the skin surface every 2 h for a consecutive 48-h period. To estimate the circadian rhythm, the data obtained were analyzed by the least-squares method and maximum entropy spectral analysis (MEM). Circadian rhythm disturbances in patients with depression were likely to be manifested in phase variability rather than in phase advance. The amplitude of body temperature of the depressed group was significantly less than that of the control group. A positive correlation between the mesor and the severity of the depressive symptoms was found. Moreover, the body temperature of the patients with affective disorders, both in the depressive and in the manic state, tended to fluctuate so much as not only to fit poorly to sinusoid curves, but also to reduce the periodicity of the circadian rhythm. On the basis of these findings, we conclude that the essential feature of the rhythm disturbances in affective disorders is not the phase shift but the instability of the circadian temperature rhythm.

Adult↗

PubMed2006

Temperature rhythm reentrains faster than locomotor rhythm after a light phase shift.

Mammalian endogenous circadian rhythms are entrained to the environmental light-dark (LD) cycle. Although the circadian rhythms of core body temperature (Tb) and spontaneous locomotor activity (LA) are well synchronized under stable LD conditions, it is thought that these two parameters are regulated by distinct mechanisms. The purpose of the present study was to examine the adaptability of these two rhythms to an abrupt change in the environmental light phase. Tb and LA were simultaneously recorded in individual mice kept under 12:12-h LD cycle conditions before and after an 8-h photic phase advance. The onset of LA required 8 days to reentrain to the new LD cycle, whereas 6 days were required for reentrainment of the acrophase of Tb. Resting Tb, i.e., the Tb level independent of LA, was extracted from the same data source. The resting Tb level exhibited a robust daily rhythm with a difference of 1.0 degrees C between LD phases. After the photic phase advance, the resting Tb rapidly reached a stable level within 4 days, whereas the uncorrected Tb required 6 days for reentrainment. Based on these findings, we revealed that, independent of LA, the adaptability of the Tb rhythm to a new light cycle is half as rapid as that of LA. These results therefore suggest that the circadian rhythms of Tb and LA are intrinsically regulated by different pacemaker or effector mechanisms.

Adaptation, Physiological↗

PubMed2000

Loss of 24 h rhythm and light-induced c-fos mRNA expression in the suprachiasmatic nucleus of the transgenic hypertensive TGR(mRen2)27 rat and effects on cardiovascular rhythms.

Immediate early genes, especially c-fos, are thought to play an essential role in photic entrainment of circadian rhythms. A special characteristic of the transgenic hypertensive TGR(mRen2)27 rat strain, expressing an additional mouse renin2 gene, is the inverse blood pressure rhythm in relation to those in heart rate and activity resulting in internal desynchronisation of these physiological rhythms. Assessment of c-fos mRNA expression by microdissection and RT-PCR in the suprachiasmatic nucleus showed, that in contrast to normotensive Sprague-Dawley rats the 24 h and circadian rhythm of c-fos mRNA expression in TGR(mRen2)27 rats is abolished. Moreover, light-induced c-fos expression within the nucleus could be found in the normotensive controls, but was absent in transgenic hypertensive rats. The light pulse applied during the subjective night, at CT 14, significantly phase delayed rhythms in blood pressure, heart rate and activity in the normotensive rats by about 2 h, whereas in the transgenic hypertensive animals rhythms in blood pressure and heart rate were unaffected, only activity showed a slight phase shift. In conclusion, these data suggest that the transgene in TGR leads not only to a disturbance of the cardiovascular system but also influences the light entrainment response, which is accompanied by a suppressed c-fos mRNA expression in the suprachiasmatic nucleus.

Animals↗

PubMed1999

Biological rhythm disturbance in depression: temporal coherence of ultradian sleep EEG rhythms.

BACKGROUND: Recent studies have suggested that major depressive disorders are associated with a breakdown in the organization of ultradian rhythm in sleep EEG. The present study used cross-spectral analysis of sleep EEG to confirm this finding, in a larger-scale study, evaluating the influence of gender and age on ultradian rhythms in depression. METHODS: Temporal coherence of ultradian (80-120 min) rhythms in beta, theta and delta, recorded from central and parietal sites, were compared in 120 symptomatic, unmedicated, depressed outpatients and 59 healthy normal controls. RESULTS: Few macro-architectural differences were noted between patients and controls. However, interhemispheric beta and theta coherence and intrahemispheric coherence between beta and delta rhythms were significantly lower in depressed patients. Coherence measures were lowest in women with depression and highest in men in the control group, but were not strongly influenced by age. Over 65% of depressed patients were > or = 2 standard deviations below normal on at least one coherence measure, in sharp contrast to less than 10% of patients on macro-architectural variables. CONCLUSIONS: It was concluded that dysregulation of ultradian rhythms characterizes the majority of depressed out-patients, primarily women, even when macro-architecture did not differentiate groups. The outcome of this study supports the view that the pathophysiology of depression is strongly influenced by gender. It was suggested that low temporal coherence in depression reflects a breakdown in the organization of sleep EEG rhythms within and between the two hemispheres.

Activity Cycles↗

PubMed1999

Correlation between the circadian sleep propensity rhythm and hormonal rhythms under ultra-short sleep-wake cycle.

The aim of this study was to clarify effects of hormonal and temperature rhythms on circadian fluctuations of sleep propensity. Ten healthy females underwent 24-h sleep deprivation and entered the circadian sleep propensity assessment setting under the ultra-short sleep-wake schedule. During the experiment, sleep propensity rhythm, rectal temperature, and 24-h serum hormone profiles (melatonin, cortisol and thyroid-stimulating hormone) were investigated. The circadian sleep propensity rhythms had two apparent peaks (afternoon and nocturnal peaks) and a trough (nocturnal sleep gate). The timings of the nocturnal sleep gate and the nocturnal peak were correlated exclusively with temperature and melatonin rhythms (P < 0.05), while that of the afternoon peak was significantly correlated with habitual wake time and melatonin rhythm. These results indicate that the circadian sleep propensity rhythm is influenced not only by the circadian pacemaker, but also by sleep habit.

Adult↗

PubMed1982

Circadian rhythm in urinary N-acetyl-beta-glucosaminidase (NAG) of clinically healthy subjects. Timing and phase relation to other urinary circadian rhythms.

Urinary N-acetyl-beta-glucosaminidase (NAG), a lysosomal enzyme of renal tubular origin, has been shown to be a sensitive indicator of renal tubular function. This study documents a circadian rhythm in the urinary activity of NAG, statistically validated and quantified by the cosinor method, in 19 female and 15 male human subjects. The acrophase of the circadian rhythm in urinary NAG activity occurs at 09(40) with 95% confidence limits between 08(40) and 12(08) and is similar to the timing of the circadian rhythm in urinary free cortisol. The circadian acrophase of urinary NAG activity lags in timing the circadian rhythms in urine volume, Na and K excretion, and urinary free adrenalin and noradrenalin, by about five to ten hours and the circadian rhythm in creatinine excretion by about 11 hours. These functions with their characteristic phase relations are part of the internal circadian time structure of the human organism, and may provide internal phase references, independent of the "time of day." This study also documents a sex difference in mesor of the circadian rhythms in urinary NAG activity, with female subjects having a higher mesor and amplitude than the male subjects, and in the excretion of creatinine and potassium, with male subjects having a higher mesor and amplitude than the female subjects.

Acetylglucosaminidase↗