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Biomedical subjects

J De Prins

Publications and source records attributed to J De Prins.

11 recordsLinked to original sources
PubMed1996

[Study of circadian rhythms of activity by actometry: preliminary results in 30 patients with metastatic colorectal cancer].

Activity circadian rhythms were measured non-invasively in 30 patients with metastatic colorectal cancer by wrist actigraphy, and compared with control data. Patients and control subjects were requested to wear the actigraph at home for 2 to 5 days. Control time-series exhibit high activity levels (150 to 350 counts/min) during daytime, followed by low activity levels (0 to 50 counts/min) during the night. In patients, the contrast between daytime activity and nocturnal sleep is noticeably less marked, and a wide inter-patient variability can be observed. This alteration of the rest-activity rhythm in the cancer group was statistically validated by autocorrelation test. Results from the cosinor and he maximal entropy spectral analysis must be interpreted more cautiously, since the prerequisites for these tests may not be fulfilled by actometric time-series. These results indicate that cancer patients may have altered rest-activity circadian rhythms. The significance and prognostic value of such alterations deserve further testing in a larger population. Actigraphy may provide a simple and innovative tool to study the circadian system in cancer patients.

Adenocarcinoma↗
PubMed1996

[The problematic cosinor].

We set off the severe deficiences of the simple cosinor method. It doesn't take error's correlation and sampling conditions into consideration. Consequently, the obtained statistical results are often misleading. This method, exclusively used by chronobiologists, should generally be avoided. References are given, containing information on adequate data processing [7, 13, 18].

Data Interpretation, Statistical↗
PubMed1993

Sightseeing around the single cosinor.

Misuses of the single cosinor analysis are numerous. We give three rules of thumb, providing guidelines as to whether results obtained from this analysis are dubious. This short note avoids mathematical development so as to be comprehensible to the nonspecialist. However, a few endnotes, give some technical comments.

Circadian Rhythm↗
PubMed1990

Computerized chronothermodynamic breast examinations under ambulatory conditions.

A new approach to the assessment of breast health was developed based upon continuous ambulatory recording of breast temperature for 24 hrs. A new data acquisition system consisting of a portable, multi-channel, microprocessor-based recorder worn on a belt was developed to record temperatures. Dramatic thermal fluctuations were noted during the recordings in response to multiple stimuli (physiological, behavioral, environmental). Specific algorithms and software programs were developed to process the thermobiologic and chronobiologic information. Data processing was fully automatic and included an examination report indicating a score and a chronothermodynamic class for each of the five areas examined on each breast. The preliminary clinical studies have concerned more than 450 patients with healthy or diseased breasts.

Ambulatory Care↗
PubMed1985

Seasonal variations in socially and legally unacceptable sexual behaviour.

The calendar dates, over the 15-year span 1966-1980, of committed rapes by eight male recidivists and offences of sexually indecent or immoral behaviour by eight other male recidivists were gathered from the files of the Préfecture de Police, Paris, France. Each offender of the first group had committed from two to six rapes, while each offender of the second had committed from two to 16 incidences of indecent behaviour. Although the reported rapes took place during several calendar years, almost all, 18 out of 22 offences, were committed by the eight rape-recidivists during the 4-month span of July-October. Single cosinor analysis of these data revealed a circannual rhythmicity (P less than 0.03) with luminal diameter being 10 August +/- 34 days (the 95% CL). The peak time of indecent sexual behaviour, exclusive of rape, against females occurred during September with secondary peaks in February and June; such offences directed against males peaked in October. 'Bootstrap' and 'Jackknife' methods confirmed seasonality within all data sets, except for the offences of indecent behaviour.

Adolescent↗
PubMed1984

Patterns of plasma melatonin with ageing and mental condition: stability of nyctohemeral rhythms and differences in seasonal variations.

Effects of ageing and mental condition on the nyctohemeral and seasonal rhythms of plasma melatonin in human subjects were investigated. Four groups of subjects were formed for a transverse study: 7 healthy young men (24 years), 6 elderly women, 6 elderly men and 6 elderly patients (2 men and 4 women) suffering from senile dementia (70-80 years). The subjects were synchronized. Blood samples were taken every 4 h during 24 h in January, March, June and October. In comparison to young men, the plasma levels of melatonin were markedly decreased (by about one half) in elderly subjects without any difference according to sex or mental condition. Nyctohemeral rhythms of the hormone were validated in all groups and at all sampling sessions. The nyctohemeral acrophases were remarkably stable (around 03.00 h) whatever the season, age or sex. A seasonal variation was found in all groups (except elderly women) with differences between young and elderly subjects: plasma melatonin levels were significantly lower in January than in June in young men, whereas in elderly subjects they were significantly lower in October than in January/March. No significant difference was observed in mesor, amplitude or acrophase of nyctohemeral and seasonal rhythms of plasma melatonin in patients with senile dementia when compared with healthy elderly subjects. The stability of the nyctohemeral peak time whatever the age group or season as opposed to the differences in the seasonal pattern of plasma melatonin according to the age groups raises the problems of both outdoor photoperiod and ageing in ruling the secretion of melatonin in man.

Adult↗
PubMed1983

[Desynchronization of the circadian rhythm of oral temperature in young human subjects with poor tolerance for night work].

15 night workers (mean age, 28 years; mean seniority 1.5 years) volunteered to measure their oral temperature (clinical thermometers 0.05 degrees C precision) 5 times/24 hrs. during a 21 day span. Time series were analyzed individually according to 3 methods. 11 of the subjects with a good tolerance had (with one exception) their prominent circadian period tau equal to 24 hrs. as well as a relatively large circadian amplitude (A from 0.19 to 0.42 degrees C). By contrast, subjects with a poor tolerance (sleep disorders, persisting fatigue, psychological troubles, etc.) had a tau value ranging from 24.9 to 25.7 hrs. associated with a relatively small rhythm amplitude (A from 0.04 to 0.13 degrees C). These results support the hypothesis that a desynchronisation of circadian rhythms help to explain why certain subjects do not tolerate shiftwork.

Adult↗
PubMedDate not supplied

Circadian rhythm of cardiac responses to vagal stimulation tests.

To evaluate the existence of a circadian rhythm in cardiac responses to vagal stimulation tests, 10 children without neurologic or cardiopulmonary disease, were studied using a standardized procedure. A trigeminal airstream stimulation test (TAS) and an ocular compression test (OCT) were subsequently performed at 4 nonequidistant hours. These 2 vagal stimulation tests were performed according to well-established, previously published techniques. Prolongation of the RR-interval during TAS and OCT was calculated and compared to the mean control RR-interval preceding the stimulation period. Prolongation of the RR-interval during the stimulation period was obtained in all instances during TAS and OCT. Chronobiologic analysis was determined by the cosinor method and bootstrap analysis. A significant circadian rhythm was found in cardiac responses to vagal stimulation for both TAS and OCT. The maximal response hour for TAS was between 9:06 p.m. and 5:18 a.m. and for OCT between 10:18 p.m. and 4:24 a.m. The mean value and 95% intervals for the cardiac responses to both vagal stimulation tests revealed, when using the bootstrap analysis, an important overlap in the hour of appearance of the maximal responses to these procedures; the bootstrap analysis of the peak of the acrophase was at 2:50 a.m. for TAS and 1:15 a.m. for OCT. Our results indicate that there is a circadian rhythm in cardiac responses to vagal stimulation tests and demonstrate a preponderance of these responses during the early morning hours.

Arousal↗
PubMedDate not supplied

Desynchronization of the oral temperature circadian rhythm and intolerance to shift work.

The present study tested the hypothesis that subjects with a good tolerance to shift work maintain the circadian period tau of their temperature rhythm equal to 24 h, while tau may differ from 24 h when subjects exhibit one or several clinical signs of intolerance. These latter are mainly: persisting sleep disturbance, persisting fatigue, changes in mood and behaviour, and digestive troubles, from gastritis to overt peptic ulcer. These symptoms were used here to classify the subjects studied. Medications, including all types of sleeping pills, are ineffective. As was the case in the present study, some subjects may tolerate shift work for 35 yr, reaching 57 yr of age without complaint, while others, after several months or many years, quite rapidly (within 6 months) develop symptoms of intolerance.

Adult↗