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Biomedical subjects

A Reinberg

Publications and source records attributed to A Reinberg.

At least 127 records · Page 7Linked to original sources
PubMed1979

Circadian and ultradian rhythms in the feeding behaviour and nutrient intakes of oil refinery operators with shift-work every 3--4 days.

Seven healthy adult men, five shift-workers and two non-shift-workers (from 21 to 36 years; mean = 26.4) volunteered to record what and when they ate, both at work and at home, every day, during eight consecutive weeks (Oct. - Dec. 1974). 1) All the subjects maintained the timing of main-meal (lunch and supper) during all shifts. 2) The major intake of protein and lipid was concentrated on the two main meals during all shifts. 3) Only the pattern of carbohydrate intake was modified by the shift-work: e.g. night-shift is associated with nibbling behaviour. 4) However, shift-work and in particular the occurence of nibbling behaviour did not result in change either in the mean 24 h caloric intake, or in the percentage of protein calories. 5) The comparison between the constancy of the timing of major meals and the shift of the timing of circadian rhythm acrophases of the 5 shift-workers leads to conclude that meal timing had a poor synchronizing effect, if any.

Adult↗
PubMed1979

Amplitude of the oral temperature circadian rhythm and the tolerance to shift-work.

The aim of the study was to test the hypothesis of a relationship between the tolerance to shift-work and the amplitude of the oral temperature circadian rhythm. Forty eight shift-workers (Rhône-Alpes Region) volunteered for this chronophysiological investigation: a) 23 steel-industry workers (SI); shift-duration: 7 days (weekly rotation); b) 25 chemical-industry workers (CI); shift-duration 2 days. The subjects' ages were roughly similar with regard to groups (SI and CI) as well as sub-groups (good and poor tolerance of shift-work). The tolerance was evaluated conventionally, according to both the existence and intensity of 3 types of medical complaint: (1) digestive troubles: gastritis, colitis, peptic ulcer etc.; (2) persisting fatigue, unusual nerviness, etc.; (3) sleep alterations. The poor tolerance was observed mostly in subjects shift-working for 10 years or more. Regular large-scaled and retested medical Hg thermometers (1/20 Celsius precision) were used. Data were recorded 2-hourly, at fixed clock hours in order to obtain individual time series. Both conventional and cosinor statistical analysis show that, in both groups, the oral temperature circadian amplitude is larger in subjects tolerant to shift-work than in subjects that have become intolerant.

Adult↗
PubMed1978

Serum magnesium circadian rhythm in human adults with respect to age, sex and mental status.

25 subjects volunteered to document circadian changes in serum magnesium. 4 groups were formed: 7 healthy young males (24.0 years +/- 3.9), 6 elderly males (82.5 years +/- 7.5), 6 elderly females 81.2 years +/- 10.7) and 6 elderly insame subjects of both sexes (80.5 years +/- 8.6). They were socially synchronized with a diurnal activity (07.00 to 21.00 for the old subjects; 07.00 to 23.00 for the young ones) and nocturnal rest. The subjects followed a spontaneous diet. Venous blood was sampled at 4-h intervals and fixed clock hours (07.45, 11.45, 15.45, 19.45, 23.45, 03.45) during 24 h. The single cosinor method was used for the statistical analysis of the time series. A statistically significant circadian rhythm is detected in three of the groups: young males, elderly males and elderly females (no rhythm detection in elderly insane subjects). The 24-h mean is higher in elderly subjects than in the young one. The rhythm amplitude is larger in elderly males than in young ones. The acrophase (peak time) location in the 24-h scale is 10.12 h for elderly females, 11.35 h for elderly males and 16.36 h for young males.

Adult↗
PubMed1978

Circadian and circannual rhythms in plasma hormones and other variables of five healthy young human males.

Every other month (plasma) and every month (urine) circadian rhythms were documented during the course of 14 months. Annual changes were validated in the 24 h mean of: plasma FSH (annual crest time: February), LH (March), thyroxine (September), cortisol (February), renin activity (April), testosterone (October), urinary 17-hydroxycorticosteroids (March), aldosterone (March), potassium (May) as well as sexual activity (September) [self-recorded daily]. Plasma prolactin did not show an annual variation. In addition, annual changes in the circadian acrophase (crest time location in the 24 h scale) occurred for some of the documented variables: plasma thyroxine, cortisol, renin activity, testosterone, urinary aldosterone and potassium.

17-Hydroxycorticosteroids↗
PubMed1978

Is the rhythm amplitude related to the ability to phase-shift circadian rhythms of shift-workers?

The magnitude of the circadian acrophase adjustment deltaphi to a phase shift of socio-ecologic synchronizers (as in shift-work) varies from subject to subject. According to J. Aschoff, the ability to adjust rapidly to a phase-shift could be associated with having a small amplitude for certain circadian rhythms. To test this hypothesis, the correlation coefficient (r) between the mean circadian rhythm amplitude A and the acrophase shift deltaphi (measured after the first night-shift) were calculated from estimates of chronobiological time series analyses (Halberg's single cosinor method). Data were obtained from two groups of selected shift-workers (20 and 5 subjects, respectively). A negative correlation between A and deltaphi (the smaller the amplitude, the greater the delpaphi) was observed in the circadian rhythms of the following variables: oral temperature (r = .63;P less than .01), peak expiratory flow (r = . 53: P less than . 01), and urinary 17-OHCS (r = . 60; P less than . 01), but not for other variables such as : grip strength, urinary K+ and Na+. The small amplitude of certain circadian rhythms could be considered as an index of an individual's ability to phase-shift easily. However, chronobiological characteristics, other than the small circadian rhythm ampliture, remain to be identified, for both a better detection of one's ability to do shift-work and a better knowledge for practical applications.

17-Hydroxycorticosteroids↗
PubMed1977

Circadian changes of the duration of action of local anaesthetic agents.

A statistically significant circadian rhythm of the duration of local anaesthesia produced by lidocaine and betoxycaine was found in both human skin and teeth. In adult subjects with diurnal activity and nocturnal rest the longest duration was found around 15.00 (3 p.m.) with a large peak-trough difference amounting to more than 100% of the 24 h mean. Such chronopharmacologic rhythm might be related to circadian rhythms in catecholamine secretion and/or in circadian changes of cell membrane properties.

Adult↗
PubMed1977

Circadian rhythms in lung resistance and dynamic lung compliance of healthy children. Effects of two bronchodilators.

In two groups of healthy children synchronized with a diurnal activity (light-on at 07.00) and a nocturnal rest(light-off at 21.00), lug resistance (R1) and dynamic lung compliance (C1 dyn) were measured at fixed clock hours (07.30, 11.30, 16.30, 22.30). The measurements were performed before and 10 minutes after the inhalation of bronchodilators (a beta-sympathetic stimulating agent (orciprenaline, dose 2 mg) and a vagolytic agent (SCH 1000, doses 80 mug and 200 mug). A circadian rhythm is detected for R1 and C1 dyn and quantified by the cosinor method. R1 and C1 dyn acrophase (peak time in the 24-h scale) are not significantly different for both groups: they are located for R1 at 05.39 and 03.31, for C1 dyn at 09.31 and 12.51. R1 and C1 dyn circadian rhythms are not detectable both after 2 mg orciprenaline and 200 mug SCH 1000 inhalation. This chronopharmacologic effect of the bronchodilators might be considered indirect evidence of a circadian rhythm in the bronchial tone. This latter may be related to circadian changes in neurovegetative activity. A dose-effect difference of the vagolytic agent on R1 at night seems to indicate a relative nocturnal prominence of the vagal tone.

Airway Resistance↗
PubMed1977

Twenty-four-hour rhythm in the bronchial hyperreactivity to house dust in asthmatics.

Four subjects, 2 males (17 and 35 yr of age) and 2 females (24 and 47 yr of age) suffering from allergic asthma were studied for 10 days in allergen-shielded rooms and without medication. Synchronization of subjects to activity was by light on at 7 A.M. and sleep by light off at midnight. A single bronchial challenge to the threshold concentration of house dust, predetermined for each subject, was presented every other day at designated clock hours such that during a 10-day study span tests were presented at the following times: 8 A.M., 3 P.M., 7 P.M., and 11 P.M. The effect upon bronchial patency determined by FEV 1.0 15 min after house dust inhalation resulted in greatest effect at 11 P.M., while that at 8 A.M. resulted in least effect. The differences were statistically significant (p less than 0.025). Peak expiratory flow (PEF), self-measured at 3-hr intervals throughout the 10-day span, revealed practically no persistence of effect for inhalation of the house dust preparations at 8 A.M.; on the other hand, considerable persistence of effect on airway patency occurred from tests carried out at 11 P.M. The differences between the 24-hr rhythm-adjusted means (mesors) in the PEF for the (24-hr) spans following house dust inhalation at 8 A.M. and 11 P.M. were statistically significant (p less than 0.025) as well.

Adolescent↗
PubMed1976

New aspects of human chronopharmacology.

Regular and thus predictable changes in biologic susceptibility and response to a large variety of physical as well as chemical agents can now be viewed as a rather common phenomenon. Chronopharmacology involves both the investigation of drug effects as a function of biologic timing and the investigation of drug effects upon rhythm characteristics. Illustrative examples of circadian chronopharmacolgy in man are discussed, keeping in mind that the objective demonstration of chronopharmacologic facts needs the use of an appropriate methodology. Circadian changes in the effects of various chemical agents have been documented: histamine, sodium salicylate, acetylcholine, halothane, prostaglandine F, reserpine, cyproheptadine, ethanol, insulin, chlorothiazide, oxymetholone, orciprenalin and SCH 1000 (bronchodilators), indomethacin, ACTH, cortisol and various synthetic corticosteroids. (three new concepts have to be considered: a. The Chronokinetic of a Drug. This term includes both rhythmic changes in the drug vioavailability, pharmacokinetic and its excretion. b. The Chronesthesy of a Biosystem to a Drug. i.e. circadian changes in the susceptibility of any biosystem to a drug. c. The Chronergy of a Drug, taking into consideration its chronokinetic and the chronesthesies of the involved organismic biosystems. Chronopharmacology is useful to solve problems of drug optimization, i.e. to enhance the desired effeciency or to reduce its undesired effects. In the human organism (among other animal species) the metabolic fate of a pharmacologic agent (as well as that of a nutrient) is not constant as a function of time. Thus, the chronobiologic approach of pharmacologic phenomena involves a lesser risk of errors and/or false information than the conventional homeostatic approach.

Biological Availability↗
PubMed1976

A chronobiological investigation of fitness for work in women on a 220 cal 24 h protein diet.

In a group of nine healthy but obese women a set of tests were used to estimate several physiological and psycho-physiological variables: self-rating of hunger, mood and physical vigor, self-recording of grip-strength, muscular fatigue test, eye-hand skill, tempo, etc. Measurements were performed every 6-hours, at fixed times, during 24-hours, once a week, before (non-restricted spontaneous food intake) and for three weeks on a 220 cal. special protein diet (calcium caseinate: 55g, associated with potassium salts, water and vitamins). Findings relating to the metabolic and hormonal variables while on this diet have already been reported: (a) The diet does not alter the circadian acrophase (peak) of the variables and (b) two distinct metabolic steps occur: first a peak of gluconeogenesis and second, a phase when ketone bodies and fatty acids are used almost exclusively as source of fuel. The present findings show that so long as nitrogen remains in balance this restricted diet (a) does not change the grip strength and the muscular fatigue test; (b) does not alter the mood, the physical vigor etc. and (c) induces a statistically significant fall in "hunger" (self-rating method). We conclude that this low protein diet is compatible with non-strenuous work.

Adolescent↗