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Biomedical subjects

J Beau

Publications and source records attributed to J Beau.

8 recordsLinked to original sources
PubMed1992

Activity rhythms in mice. III: Stability and plasticity of rhythm characteristics in experimental and environmental conditions.

The expression of a biological rhythm as measured by a given descriptor results from a set of components: the subject, the measuring device, and the experimental conditions. Rhythm of activity under four experimental conditions was observed in two strains of mice: BALB/c and C57BL/6. Condition 1, the optimal normal situation, was used as a reference; condition 2 was a retest of the animals used in condition 1 twelve days later; condition 3 tested animals for a period of 3 days in a food-deprivation situation; in condition 4, animals were isolated for 2 weeks prior to testing. Data analysis of rhythm of activity in the synchronic mode is based on a series of tests in the frequency and temporal domains. Analysis of condition-linked variation in the findings indicates that these parameters are only slightly affected by the four experimental conditions. The results, however, can be hierarchized according to condition and according to the kind of parameter. The temporal parameters are more sensitive than the frequency parameters, the least sensitive being the temporo-frequential measures. Isolation produces the greatest variation in parameter magnitude. The results show that rhythm of activity is fairly stable across a number of experimental conditions, a finding that could considerably simplify experimental protocols.

Animals↗
PubMed1991

Activity rhythms in inbred mice. I. Genetic analysis with recombinant inbred strains.

Rhythm of activity of inbred mice was recorded automatically by a set of actographs. This rhythm was characterized by six indices in the temporal and frequency domains. Two methods of genetic analysis were applied to these indices using parental strains BALB/c and C57BL/6, the reciprocal F1's, and the seven recombinant inbred strains (RI). Findings on the F1's show no maternal effect but indicate dominance and heterosis. The RI method successfully rejects the hypothesis of a monogenetic correlate for all measures. In line with F1 data, it demonstrates the presence of a polygenetic correlate: at least one other locus is involved in each of the six outcome parameters.

Activity Cycles↗
PubMed1990

The influence of the athymic mutation nude on the components of the circadian rhythm of activity in mice.

The mutation known as nude brings about the lack of a thymus gland in mice. This immunodeficiency akes it possible to graft normally unaccepted, human cancerous tumors onto the mouse. Consequently, this animal is frequently used as a model for evaluating anti-cancer therapies. The effect of this mutation on biological rhythms constitutes a necessary step before using this model for cancer chronotherapy research. We evaluated the circadian and ultradian components of the rest-activity cycle in the following strains of mice: C57BL/6 with homozygous nu/nu, heterozygous nu/+, thymectomised +/+, and sham-operated +/+. The amount of activity was reduced in nu/nu as compared to the other groups. Nonetheless, neither the nude mutation nor thymectomy yielded any notable change in the circadian rhythm of activity.

Activity Cycles↗
PubMed1990

The thermometer and the calorimeter, or the best choice for data acquisition in the sampling of biological rhythms.

The comparison between measurements effected by different apparati shows that a given class of instruments provides an integral set of measurements. This characteristic has a certain disadvantage: the modification of the spectral bandwidth is limited to an attenuation of 3 dB. However, it also has certain advantages. The integral measurement (or the counting measurement) makes it possible to satisfy Shannon's sampling criteria by avoiding the necessary, anti-aliasing filtering which is commonly impossible to realize on measurements of a biological nature. A second advantage is linked to the reduction of the background noise on the band.

Calorimetry↗
PubMed1988

Preaveraging or postaveraging of data measured in chronobiology: will the mean mouse please stand up?

Chronological measures are often made on several subjects, or for a period of days, or both, to define cycles of 24 hr in order to obtain a variety of information which can be submitted to statistical tests to characterize the subjects. In this paper, a simple theoretical model for two subjects is presented to examine the consequences of preaveraging. Preaveraging is defined as the summing of those temporal values which define the phenomenon in question. This type of operation is in fact the equivalent of filtering with moving averages. This model is then extended to N subjects exhibiting randomly assigned shifts. The disadvantages of preaveraging are illustrated from data drawn from experimental studies on mouse activity in three inbred strains: DBA/2, BALB/B6 and C57BL/6. Different effects of preaveraging, both voluntary and involuntary, are described. It is shown that preaveraging masks features that in fact discriminate across strains whereas postaveraging, because it does not suppress information, makes it possible to define the parameters of an "average" subject.

Animals↗
PubMed1988

[Polygenic correlates of characteristics of the rhythm of activity in mammals: study of 2 inbred C57BL/6 and BALB/cBy mouse strains].

Rhythm of activity in inbred strains of mice in synchronic LD 12:12 was shown to be characterized by six indices: amount of activity, circadian level, pulsatile activity, ratio of nocturnal/diurnal activity, and two temporal frequency descriptors. Genetic analysis of rhythm of activity was conducted on parental strains C57BL/6By and BALB/cBy via the reciprocal F1s and the seven recombinant inbred lines. No maternal effect for the reciprocal F1s was observed. The findings indicate dominance and heterosis effects for the F1s. Heterosis tends towards a better fit of rhythm to natural day/night synchrony. RI findings eliminate the hypothesis of monogenetic correlates for all six parameters investigated, and in conjunction with the F1 analysis demonstrate that each indices have polygenic correlates with at least one different locus for each of the measures of activity.

Activity Cycles↗
PubMed1986

Microcomputer-driven digital data processing of mouse actograph activity.

The system is designed to measure the ambulatory activity of each of a set of eight mice, using a group of actographs driven by an inexpensive microcomputer, thus avoiding unnecessary usage of a costly instrument over an extended period. A toric actograph was chosen since it is sensitive to ambulatory activity even at low amplitudes. In this computerized system, actograph data are recorded on audio cassettes during the experiment, and later reread by an Apple II microcomputer for storage on floppy disks. This makes it possible to perform all types of mathematical treatment at a later date. Since the experiments last for several days and the environment is kept constant, activity rhythms can be studied. The data processing takes place off-line and employs digital filtering, which is shown to be preferable for the presentation of temporal data to a simple smoothing, by a moving average. Spectral analysis is obtained through a discrete Fourier transform. Two methods of reconstitution of temporal curves from the frequency analyses are presented: an inverse Fourier transform, or summation of the Fourier series.

Animals↗