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Biomedical subjects

A Reinberg

Publications and source records attributed to A Reinberg.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

[Utilization of a self-contained psychometry-oriented device, for study of affective and cognitive function of a subject].

We appraised the possibility to use the Psycho-Log 24, an ambulatory, adapted to chronopsychometry device, which realizes simplified questionnaires and performance test adaptable to each subject; this device has dimensions like a pocketbook; its storage capacity is compatible with a long time use. 9 adult volunteers (8 healthy subjects and 1 depressive patient) participated to this study. All of them effected reaction times (TRS) during 3 to 31 days at the rate of at least 4 sessions/day; some of them completed mental calculations (CM), letters cancellations (BRL) and auto-estimation scales (from 1 to 9 items, also measured by a classic method). For TRS and all the subjects, the frequencies histograms calculated by hour and on a 24 h scale, showed a bimodal variation, with a major peak suggesting a circadian rhythm. 5 subjects had different time for the daily best performances of each hand (shifted from 5 to 12 h). In the healthy adults, for BRL and CM, the best performances in speed and precision are shifted and could be related to the "fatigue" auto-estimated peaks. There is a significant correlation between auto-estimations by Psycho-Log and the classic method. The coherence between the auto-estimations of the depressive subject is strong during the remission stage, and lower during the relapse stage. The used method seems an effective mean to know the temporal structure of the cognitive and affective functions of a subject, and to estimate the preserving of this structure; the method first could constitute an exploratory mean for an objective evaluation of the drugs effects and patients quality of life, secondly could be implicated in researches with diagnosis target.

Adult↗
PubMedDate not supplied

[Annual and circadian rhythms in plasma testosterone of five healthy young male Parisians (author's transl)].

Every other month, during the course of 14 months, the circadian rhythm in plasma testosterone (among others variables) of 5 healthy males (26 to 32 years) was documented. Subjects' synchronization : light-on at 07 +/- 1 hr; light-off at 23hr +/- 1.5 hr all the year long. Blood sampling 4-hourly, at fixed clock hours during 28 hrs, for radioimmunologic testosterone determinations. The cosinor method was used for statistical analyses. An annual rhythm in the testosterone 24-hr mean is detected (p less than 0.025) with a peak in October (from 16 July to 26 December, with 95% confidence limits). Annual mean (+/- 1 SE) - 759 (+/- 26)ng/100 ml. Peak-through difference = 107 ng/100 ml (from 106 to 290 with 95% confidence limits). The timing of the testosterone circadian peak, in the 24 hr-scale varies also in the course of the year. The peak is found around 08(00) in May and around 14(00) in November, this phase-shift being statistically significant (p less than 0.05). The sexual activity (daily self-recording) also has an annual rhythm with a peak in October.

Adult↗
PubMedDate not supplied

[Chronopharmacology].

Explore the source record for details and available documents.

Chronobiology Phenomena↗
PubMedDate not supplied

[Chronotherapy of tenoxicam].

A study was carried out in order to investigate the chronotherapy (dosing time dependency) of an NSAID, the tenoxicam administered in ankylosing spondylitis, rheumatoid arthritis and osteoarthritis of the hip. These variations in efficacy exist as much for pain as for stiffness and maximum efficacy is obtained with administration at 8 am or 12 pm. Since the tolerance was good, we recommend midday as an optimal once-a-day dosing time.

Adult↗
PubMedDate not supplied

Clinical chronobiology: relevance and applications to the practice of occupational medicine.

In this chapter, the topic of medical chronobiology has been presented. Emphasis has been placed on issues related to clinical and occupational medicine. Results of initial studies conducted primarily by clinical pathologists indicate that the results of several commonly ordered diagnostic tests are influenced in a significant way according to the circadian time when samplings or tests are conducted. In addition, the pharmacokinetics and pharmacodynamics of medications can vary significantly according to their administration time. Indeed, the safety as well as efficacy of certain medications or dosage forms are circadian time dependent. A new thrust in the clinic is the application of chronotherapeutics to maximize the effectiveness and safety of medications. For the occupational health practitioner, the topic of medical chronobiology offers new perspectives to better address common problems experienced in clinical occupational medicine. First, the utilization of time-qualified (for circadian rhythmicity) reference values serves to differentiate with greater precision normal from unusual test findings; for example, among those arising during the pre-employment and scheduled follow-up physical examinations. Second, it provides better insight into the basis for the biological intolerance to rotating shiftwork. Too often, employee complaints of shiftwork intolerance are met with skepticism by members of the management and/or medical staff. The phenomenon of biological intolerance to rotating shiftwork is real. It has only been during the past decade that shiftwork intolerance has been demonstrated to have a chronobiologic basis. It seems that persons who possess a weak circadian time structure, that is, rather low-amplitude bioperiodicities, are more prone to develop biological intolerance to shiftwork later in life. Those endowed with a strong (high-amplitude) time structure are least prone. Thus, although persons with a weak circadian time structure might be at an advantage in tolerating rotating shiftwork schedules while young, they appear to be at a high risk of developing intolerance to it later in life. It is hypothesized that a weak circadian time structure predisposes one to desynchronization when subjected to work schedules entailing regular disruption of the activity-rest synchronizer schedule. The mechanisms underlying this biological intolerance to shiftwork require much additional investigation.(ABSTRACT TRUNCATED AT 400 WORDS)

Chronobiology Phenomena↗
PubMedDate not supplied

Internal desynchronization of circadian rhythms and tolerance of shift work.

Fifteen male subjects including 12 shift workers (oil refinery operators) volunteered to document circadian rhythms in sleep-wake, grip strength of both hands, peak expiratory flow, heart rate, self-rated drowsiness, fatigue and attention. Each of these variables was measured 4 to 6 times/day for 2 to 3 weeks. In addition, both axillary temperature (with a shielded probe) and wrist activity were almost continuously recorded at 15 min intervals during the same time span. Individual time series were analyzed according to several statistical methods (power spectrum, cosinor, chi 2, etc.), in order to estimate the prominent circadian period tau and to evaluate both individual and subgroup differences with regard to tolerance of shift work, age, duration of shift work. The present study confirms for continuously recorded temperature and wrist activity, grip strength of both hands, heart rate and peak expiratory flow that intolerance of shift work is frequently associated with an internal desynchronization. However, this conclusion cannot be extended to circadian rhythms in self-rated drowsiness, fatigue and attention. The internal desynchronization among several circadian rhythms supports the hypothesis that these latter are driven by several oscillators, with presumable differences between right and left hemispheres as suggested by unequal values of tau in rhythms of both hand grip strength. Since an internal desynchronization can be observed in tolerant shift workers having no complaint, it is likely that symptoms of intolerance are related to the subject's sensitivity to internal desynchronization rather than to the desynchronization itself.

Adult↗
PubMedDate not supplied

Aspects of chronopharmacology and chronotherapy in children.

Pediatric studies involving chronopharmacology until now have been limited mainly to investigation of circadian patterns in children of 6 to 15 years. This means that: a. data on newborns and even on infants of one year or younger are not available, and b. other bioperiodicities, such as those of one year (infradian rhythms), have not yet been explored in older children. Biological time-related changes have been documented for phenytoin and theophylline with regard to their pharmacokinetics and for orciprenaline, ipratropium bromide, corticosteroids and anticancerous agents with regard to their effectiveness. Despite the small number of investigations performed to date, results indicate that: a. more comprehensive and precise characterization of pharmacokinetic and pharmacodynamic phenomena can be achieved by a chronopharmacological approach than the conventional one and, b. better therapeutics can be achieved using chronopharmacological facts since an appropriate timing of medicines with regard to biological rhythms is likely to enhance desired and/or reduce undesired effects.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Dosing time and sex-related differences in the pharmacokinetics of cefodizime and in the circadian cortisol rhythm.

Two g cefodizime i.v. administration at 00:00, 06:00, 12:00 and 18:00 respectively, to 8 male and 8 female, young healthy volunteers, has shown: 1. a sex-related difference in both plasma (AUC) and total cumulative excretion of the agent with larger values in females than in males; 2. a dosing time-related difference in plasma (AUC) with the largest values for Rx at 00:00 and lowest for Rx at 18:00 in both males and females; 3. a dosing time-related difference in urinary concentration of cefodizime with largest values for Rx at 06:00 and lowest for Rx at 12:00. These urinary changes were highly correlated with changes in AUC for each dosing time; 4. no dosing time-related changes were observed for plasma T1/2 as well as cumulative urinary excretion of cefodizime; 5. curve patterns of plasma cortisol had similar aspects for both control and Rx at 00:00 with no sex-related differences. Curve patterns differed from control for other dosing times (p less than 0.005 to p less than 0.001 with ANOVA tests).

Adult↗
PubMedDate not supplied

Persisting and unaltered circadian rhythms of six healthy young men with a night-work shift every 48 hrs and a 2% CO2 atmosphere during a 4-week span.

Six apparently healthy young males (20 +/- 0.5 years of age) lived in a specially designed laboratory for a 1-week span in normal air, followed by 4 weeks in a 2% CO2 atmosphere and thereafter 1 week again in normal air. Room temperature was 24 degrees C. +/- 1 degrees C.; relative hygrometry 75% +/- 5%. With respect to socio-ecologic time clues and cues, the subjects were not isolated. The subjects' social synchronization was altered only by the shift-work schedule (light-on, 07(00); light-off, 22(30) on normal days). Every other day each subject had a 3-h night task, located between 23(00) and 07(00). Once a week, during 48 hrs (Saturday and Sunday) a set of physiologic variables was documented every 4 hrs in order to study their circadian changes: oral temperature, peak expiratory flow, grip strength, arterial blood pressure, tempo, and urinary pH, volume and potassium excretion. As far as rhythms are detectable (cosinor method) the most striking result is that both rhythm acrophases and amplitudes do not show any statistically significant changes when comparing either night-work versus day-work and/or normal air versus air with 2% CO2. Both 3 hrs of night-work every other day and an unusual amount of CO2 do not alter the parameters characterizing the circadian rhythms considered. The absence of desynchronization during night-work could be related to: 1) the speed of rotation in the shift-work; 2) the short duration of night-work; and 3) the youth of the subjects.

Adult↗