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Biomedical subjects

J Aschoff

Publications and source records attributed to J Aschoff.

At least 19 recordsLinked to original sources
PubMed1992

Estimates on the duration of sleep and wakefulness made in isolation.

Fifteen subjects who lived singly in an isolation unit without temporal cues were asked to note every day after awakening how many hours they thought they had slept, and in the evening before retiring how many hours they had been awake. These estimates of the duration of sleep and wakefulness were compared with the intervals between two signals given by the subjects by pressing a button at the time of waking up and when turning off their bedside reading lamp. The results can be summarized as follows: (a) the daily estimated durations of sleep and wakefulness were positively correlated with the actual durations in all but one subject; (b) sleep and wake times were better estimated in the presence of a light-dark cycle even if the subjects were not entrained by the zeitgeber; (c) for both episodes, there was a consistent trend from an overestimation of relatively short to an underestimation of long durations; (d) with equal durations in the two episodes, sleep was estimated to be shorter than wake time; (e) the most accurate estimates centered around 10.5 h of sleep and 13.5 h of wake time; (f) the sleep and wake times added up to 24 h in subjects who did not deliberately "compensate" for relatively long sleep estimates with a short wake estimate, with the full cycle being adjusted to 24 h.

Activity Cycles↗
PubMed1991

Activity in anticipation and in succession of a daily meal.

When exposed, in otherwise constant conditions, to a schedule with one single meal per day, rodents anticipate the time of food availability by an increase in locomotor activity while the main circadian rhythm continues to free-run with a period different from 24 h. The anticipatory activity (AA) is considered a component which is uncoupled from the light-entrainable circadian system and controlled by a food-entrainable oscillator. In this report it is shown that, in addition to AA, sometimes a burst or band of activity appears which succeeds the feeding time (SA). AA and SA seem to belong to one another, both being controlled by the same food-entrainable oscillator. The band of activity constituted by the combination of both AA and SA, though temporarily suppressed during and immediately after the meal, follows, as a whole, the rules of entrainment as known from circadian systems.

Animals↗
PubMed1990

Interdependence between locomotor activity and duration of wakefulness in humans during isolation.

Locomotor activity was recorded in 14 subjects who lived singly in an isolation unit for 16 to 88 days. Their free-running circadian rhythms had a mean period of 25.9 h, with individual means in the duration of wakefulness (alpha) ranging from 12.1 to 22.9 h. Intraindividually, the hourly means of activity were negatively correlated with alpha to such a degree that the total amount of activity per 'day' remained constant irrespective of large variations in alpha.

Circadian Rhythm↗
PubMed1990

Annual rhythm of human reproduction: I. Biology, sociology, or both?

The annual rhythm of human reproduction was analyzed on the basis of more than 3000 years of monthly birth rates covering 166 regions of the globe. The following variables were used to characterize the annual rhythm of human conception (birth minus 9 months): amplitude, phase of maximum and minimum, phase and length of the time span when rates are above the annual mean (alpha), and the steepest upward slope (delta max) of the curve fitted to the rates. The waveform of the annual rhythm is characteristic for geographical regions (e.g., unimodal or bimodal) and persists as such for many years. In most countries, the onset of alpha coincides with delta max and lies close to the spring equinox. This phase of the rhythm is the most stable over time. In many populations, the rhythm has changed in recent years, specifically in amplitude and phase. The phase of the rhythm depends on latitude, with a 6-month difference between the Northern and Southern Hemispheres. The latitudinal distribution of amplitudes is less systematic. In spite of the many social influences on timing of conceptions, we conclude that the seasonal component in human reproduction is based on biological factors.

Birth Rate↗
PubMed1990

Annual rhythm of human reproduction: II. Environmental correlations.

Annual rhythms of human conception rates (based on a worldwide selection of statistics) were correlated with photoperiod, monthly averages of daily hours of sunshine, minimum and maximum temperature, and humidity. Our results show for the first time on a global scale that photoperiod, as shown for many animals, may also influence the physiology of human reproduction. At higher latitudes, where changes in daylength are pronounced, a steep increase in human conceptions coincides with the vernal equinox. Temperature also appears to be a major influencing factor. Conception rates are above the annual mean at temperatures between 5 degrees and 20 degrees C, and temperature extremes decrease the probability of conceptions. In regions with cold winters and moderate summers, the number of conceptions correlates positively with temperature; close to the equator, where winters are more moderate than the hot summers, this correlation is negative. Regions with both hot summers and cold winters tend to have a bimodal conception rhythm. The influence of photoperiod is dominant before 1930, whereas the impact of temperature dominates in later years. With industrialization, people are increasingly shielded from both photoperiod (by indoor work) and temperature (by heating and air conditioning), which may explain the deseasonalization of the human conception rhythm. Photoperiod and temperature and the specific changes in their impact can account for several features of the annual human conception rhythm: latitude dependence, waveform, phase and amplitude, and their specific changes over time.

Climate↗
PubMed1989

[Recurrent functional ovarian cysts following laparoscopy fenestration].

The laparoscopic fenestration of functional ovarian cysts with a benign appearance is well known. After aspiration of the contents of the cyst, a window is cut in the cyst wall for an endocystic inspection. In this way, samples for cytology as well as histopathology are obtained. A laparoscopic fenestration was performed on 104 patients. During a mean follow-up time of 20 months, we found a recurrence of 8% in 91 patients. In the presence of pelvic adhesions, the functional cysts tend to reoccur. Corpus luteum cysts have a higher recurrence-rate than follicular cysts. In our study postoperative hormon-therapy recorded no protective effect.

Endometriosis↗
PubMed1989

Masking of circadian activity rhythms in canaries by light and dark.

Canaries (Serinus canaria) were kept singly in cages placed in an artificially illuminated, soundproof cabinet. Perch-hopping activity was recorded by means of a computer system. In three series of experiments, the activity rhythms of the birds were entrained to 24 hr by light-dark (LD) cycles with 4, 12, or 20 hr of light (L), respectively. The intensity of illumination was 10 lux in L and 0.25 lux in darkness (D). Under LD 4:20 and 12:12, the intensity of D was increased daily at the same zeitgeber time to 1 lux for 1 hr (L pulse) during about 8 consecutive days. This sequence was followed by 8 days without L pulses before giving another series of L pulses at a different zeitgeber time. Under LD 20:4, the intensity of L was decreased to 1 lux for 1 hr (D pulse). The activity of all birds was more or less increased by the L pulses (positive masking) and decreased by the D pulses (negative masking). The level of masking activity during the L and D pulses depended on the circadian phase at which the pulses were administered. Positive masking by L pulses was minimal about 5 hr after the beginning of D, and increased steadily thereafter. Negative masking by D pulses was maximal at the beginning and the end of L, and minimal during the middle.

Animals↗
PubMed1988

VEP, physiological and psychological circadian variations in humans.

Amplitudes and latencies of components of visual evoked potentials (VEPs) were analysed during the 24-h cycle in humans. Circadian variations of other physiological parameters (oral temperature, urine volume and urinary potassium excretion) and of psychomotor performance (grip strength, tapping rate, visual reaction time and performance on a letter cancellation test) were also assessed. Eight male volunteers (aged 20-34 years) were tested twice over a period of 30 h. Test sessions took place every 3 h (1100 hours, 1400 hours etc.). VEPs were elicited by checkerboard pattern reversals. Significant circadian variations in the VEPs were found for the latencies of the P100 and N140 components, which were longest between 2 a.m. and 5 a.m. (P100: 103 ms; N140: 138 ms) and shortest at about 5 p.m. (P100: 97 ms; N140: 130 ms). Pronounced circadian variations were also observed in physiological parameters and in psychomotor performance measures. Circadian variation of oral temperature was correlated with the 24-h profiles of most of the other variables. Time courses of VEP latencies and oral temperature were moderately negatively correlated. However, from the data presented it seems premature to conclude that there is a common pacemaker for the circadian variations of the different parameters investigated.

Adult↗
PubMed1988

Masking of circadian activity rhythms in hamsters by darkness.

Wheel-running activity was recorded in male golden hamsters (Mesocricetus auratus) kept in constant dim illumination. For periods of several weeks the lights in the cabinet were turned off daily at the same time of day, either for 1 h or 2 h. Despite these periodically recurring dark pulses, the circadian activity rhythms continued to free-run, and consequently crossed through the pulses at a more or less regular speed. During a dark pulse, the activity was usually enhanced. The amount of these masking effects varied with the phase of the circadian cycle at which the pulse occurred. The responses were maximal a few hours after the onset of spontaneous activity, and minimal during the rest-time of the animal.

Animals↗
PubMed1986

Circadian activity rhythms in squirrel monkeys: entrainment by temperature cycles.

Eight squirrel monkeys (six male, two female), kept singly in wire-mesh cages, were housed in groups of three in a climatic chamber. Locomotor activity was recorded by means of photocell systems or mobile climbing trees. For time spans of several weeks, the animals were alternately exposed to each of three different conditions: (1) constant conditions at various levels of light intensity and ambient temperature; (2) a 24-hr light-dark (LD) cycle at constant temperature; (3) a 24-hr cycle of low (about 17 degrees C) and high (32 degrees C) temperature in constant illumination (LL). In constant conditions, the free-running activity rhythms always had periods longer than 24 hr, without systematic dependencies on ambient temperature, but with a tendency to lengthen the period when the intensity of illumination was increased. All animals were entrained by a weak LD zeitgeber (10:1 lux). Exposure to cycling ambient temperature resulted in entrainment in about 45% of all tests. Usually, the entrained animals were active during the cold fraction of the cycle, but some records suggested entrainment in a warm-active mode. In addition, temperature changes exerted strong masking effects, mainly with increases of activity during the warm fraction of the cycle.

Animals↗
PubMed1986

Meal timing in humans during isolation without time cues.

In an underground isolation unit, 46 subjects lived singly without time cues under conditions of self-selected light-dark (LDs) cycles or constant illumination (LL). They all developed free-running circadian rhythms that either remained internally synchronized (i.e., with equal periods in all functions; n = 24) or became desynchronized by a sudden lengthening (n = 14) or shortening (n = 8) of the sleep-wake cycle. Six further subjects were synchronized to 24 hr by an externally controlled LD cycle. All subjects had to prepare their own meals. Signals were given by the subjects when they woke up, had a meal, and retired. Of the 52 subjects, 43 consistently had three meals per "day," and 9 had two meals, irrespective of the length of the circadian cycle and despite the fact that, due to desynchronization, wakefulness varied from over 30 hr to less than 12 hr. The intervals between meals, between wake-up time and breakfast, and between last meal and bedtime were "stretched" or "compressed" in strong proportionality to the duration of wakefulness.

Adult↗
PubMed1986

Effects of feeding cycles on circadian rhythms in squirrel monkeys.

Squirrel monkeys (Saimiri sciureus) were housed singly in cages equipped with a tree for climbing to measure locomotor activity, and with a movable food cup that could be arrested automatically. The animals were kept in continuous dim illumination (LL), twice interrupted by several weeks of entrainment by a light-dark (LD) 12:12 cycle. Apart from three control sections in which the food cups were unlocked continuously (ad libitum feeding), food was accessible for 3 hr per day only, with interfeeding intervals varying from 23 to 26 hr (periodic restricted feeding, or RF). During LD entrainment, the imposition of an RF schedule resulted in anticipatory behaviors, represented by increased tugs at the food cup and a pause in locomotor activity preceding the feeding time. In LL, the animals showed free-running circadian rhythms of locomotor and "feeding" activity that nearly always persisted when ad libitum feeding was replaced by RF. The period (tau) of the free-running rhythm was slightly modulated in relation to the varying interfeeding intervals (T), but entrainment was never achieved except in one test with an animal whose tau was very close to T. It is concluded that periodic availability of food represents an extremely weak zeitgeber, if any, for the circadian pacemaker of squirrel monkeys.

Animals↗
PubMed1986

[Surgically treated carpal tunnel syndrome--clinical and electrophysiologic follow-up].

The carpal tunnel syndrome is described as a compression of the N. medianus under the retinaculum flexorum with the causes for this syndrome being of the most varied nature. The aetiology is multifactorial with frequent alterations of the connective tissue being observed in the histological specimen, i.e. chronic inflammatory proliferations or fibrotic degenerations. Direct pressure measurements have shown that the pressure is markedly higher both at rest and extension or flexion as compared to normal healthy subjects. An exact diagnosis requires a measurable prolongation of the distal motorial latency. Surgery is the treatment of choice to ensure perfect recovery. For this purpose the retinaculum flexorum must be entirely split, and our experiments have shown that the splitting of the epineurium yields good results. The microsurgical interfascicular neurolysis, however, should be considered in special cases only. Complaints tend to disappear fairly quickly in the majority of cases, i.e. pain recedes by 90%, sensitivity disorders by more than 70% and muscle atrophy by 50%. The operation enables a measurable improvement of the distal motorial latency. The incidence of postoperative complications is relatively low, and if they do occur, then they are negligible and without any bearing on the final surgical result. Persistent residual complaints are very often due to other accompanying diseases such as cervical vertebral column syndrome, cervical ribs etc.

Carpal Tunnel Syndrome↗
PubMed1985

On the perception of time during prolonged temporal isolation.

UNLABELLED: In an underground isolation unit, 42 subjects were living singly for time spans of at least 7 days up to more than a month. Except three who were entrained to 24 h by an externally controlled light-dark cycle (LD), subjects had no time cues and developed free-running circadian rhythms either in self-selected LD-cycles or in constant illumination. Each subject had to give a signal whenever he thought that 1 h had passed. In addition, 30 subjects produced short-time intervals within the range from 10 to 120 s. RESULTS: The 1-h estimates were longer than 1 h, and had a strong positive correlation with the duration of wakefulness alpha as well as with the length of the circadian cycle. The short time estimates were equally distributed between under- and over-estimation of the required interval, and they were neither correlated with the 1-h estimates nor with alpha. It is concluded that long and short time estimates are based on different mechanisms.

Adolescent↗
PubMed1979

Circadian rhythms: influences of internal and external factors on the period measured in constant conditions.

The article reviews most of the data available on the period tau of freerunning circadian rhythms, measured in constant conditions. Emphasis is placed on the effects of light intensity and ambient temperature on tau, with references to influences of other external as well as internal factors. In the introduction, examples are given of spontaneous and induced variations in tau and its dependence on the experimental history. The discussion concentrates largely on results obtained from arthropods and vertebrates.

Age Factors↗
PubMed1979

Circadian rhythms of locomotor activity in the squirrel monkey, Saimiri sciureus, under conditions of self-controlled light-dark cycles.

Locomotor activity was recorded from three squirrel monkeys, Saimiri sciureus, housed singly in cages inside a sound-proof chamber. Each animal was exposed twice to each of three conditions; continuous dim illumination (dim LL), continuous bright illumination (bright LL), and conditions in which the animal could turn on bright light by itself (self-controlled light-dark cycle: LDs). The mean circadian period, tau, the activity time, alpha, and the amount of activity, A, were computed for each single condition. It was found that, in LL, tau, alpha and A were positively correlated with the intensity of illumination. In LDs, tau was longer and A larger than in either dim or bright LL. The lengthening of tau in squirrel monkeys by a self-controlled light-dark cycle is compared with similar findings in birds and man, and is discussed in view of the observation that the tau-characteristics of diurnal mammals deviate from those known from other diurnal species of vertebrates.

Animals↗