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M Stupfel

Publications and source records attributed to M Stupfel.

At least 19 recordsLinked to original sources
PubMed1991

The occurrence and functions of ultradian rhythms.

Ultradian oscillations with periods between 5 min and 4 h have been described in cell-free extracts, single-celled eukaryotes, cultured cells and embryos. Whereas some of these potentially oscillatory systems (e.g. glycolysis) may only exhibit this type of behaviour rarely if at all in vivo, other ultradian oscillators in lower eukaryotes are rhythms and probably have timekeeping functions. Rhythms with ultradian periods of 10 min to 20 h in oxygen consumption and carbon dioxide production have also been studied in endotherm animals: these rhythms may be modified by variations of environmental parameters and by circadian and infradian synchronizers. Interspecies and interstrain differences strongly suggest that these rhythms are endogenous and have a genetic origin. We suggest that the temporal organization of biochemical and physiological processes facilitates optimization of thermodynamic maintenance of the organism within the random fluctuations of its physicochemical environment and contributes to genetic selection.

Animals↗
PubMed1990

Ultradian, circahoral and circadian structures in endothermic vertebrates and humans.

1. For more than 30 years many studies have been carried out concerning rhythms with periods approaching 24 hr (circadian rhythms). 2. The latter have been demonstrated as resulting from environmental 24 hr synchronizers (zeitgebers), but they usually persist in the absence of a 24 hr synchronization, which proves their endogenous nature. 3. Biological rhythms with periods less than 20 hr (ultradian rhythms) and particularly those approaching 1 hr (circahoral rhythms) have been determined: for motility, rest-activity, sleep phases, endocrine secretions and other physiological functions. 4. These ultradian and circahoral rhythms have been found in rodents, birds, monkeys and humans. 5. Existing at all stages of ontogeny, they have been proved to be endogenous and species and strain specific. 6. As these ultradian rhythms can be influenced by environmental factors and sometimes by circadian rhythms they are not truly periodic, so therefore cannot be computed by the usual processes of mathematical time analysis.

Activity Cycles↗
PubMed1979

[Ultradian (between 5 and 70 minutes) respiratory (VO2, VCO2) rhythms of 4 small vertebrates used in biomedical research].

Four laboratory Vertebrate species with a predominant activity, either diurnal (Coturnix coturnix japonica), nocturnal (Rattus norvegicus, Mus musculus), or equivocal (Cavia porcellus), present, in usual housing conditions (temperature 20 degrees C, hygrometry 60-70%, acoustical background 70 dB, LD12:12 lighting L = 150 lx), food and water ad libitum, ultradian respiratory (VO2, VCO2) rhythms of short periods. The frequencies of these rhythms are independent of food intake and activity variations correlated to the lighting phase and regimen (LD, LL). The period (tau) of these ultradian respiratory rhythms is in isolated animals, between 5 and 70 min., according to the species studied. Grouping of several individuals of a same species, in a ventilated chamber, modifies the statistical distribution of the periods of the ultradian rhythms, but does not change the interspecies differences.

Animals↗
PubMed1979

Lifelong variations in heart rates in SPF Sprague Dawley rats of both sexes. Statistical correlations with body weights.

In unanesthetized Sprague Dawleys, SPF, of both sexes, housed in DL12:12 (100lux), at a temperature of 18--23 degrees C and a hygrometry of 60--75%, the measurements of heart frequencies during most part of their life point out a continuous decrease with age and an always higher (40--20 c.min-1) heart rate in females than in males. Significant correlations between heart rate and body weight can account for these heart rates variations. Between the ages of 72 and 589 days, which corresponds to the growth period, a linear relationship was established between Log heart rate (y; c. min-1) and Log body weight (x; gram); for males: Log y = 0.122 Log X +Log 938 and for females: Log y = -0.166 Log X + Log 1217. After the age of 600 days, which corresponds to senescence, decreases in heart rate as well as in body weight were observed in both sexes.

Age Factors↗
PubMed1979

Action of psychoactive drugs on sex-related differences of OF1 mice; intraspecific aggressiveness and acute hypoxia survival.

The purpose of this study was to examine (1) whether there were a relationship between the sex-related differences in 51-day-old OF1 mice, regarding male aggressiveness and their sensitivity to an acute hypoxic (nitrogen) 50% lethal challenge, and (2) whether these sex-related differences could be modified by psychoactive drugs acutely injected at nonincapacitating doses. The introduction of a previously isolated male in grouped (10) mice decreased survival to the hypoxic challenge more in females than in males. The previously isolated male, which acted as an 'aggressor' with grouped mice (fights and flights in male groups, and mounts in female groups), had a higher hypoxic mortality than the mice of the groups under aggression. Psychoactive drugs were intraperitoneally injected in grouped mice before the introduction of the male aggressor. Clorazepate (5 and 25 mg/kg) abolished the sex-related difference in hypoxic survival in groups in the presence of, but not in the absence of, the previously isolated male. Conversely, hydroxyzine (5 mg/kg) and dexamphetamine (1 mg/kg) suppressed the sex-related difference only in the absence of the aggressor. The effects of these drugs appeared to be associated more with flight than with fight reactions provoked by the introduction of the male aggressor. A deep hypothermia was noted in clorazepate-treated mice at the issue of the hypoxic challenge.

Aggression↗
PubMed1978

[Aggression toward groups of male and female OF1 mice by a male congenere and survival to acute hypoxia].

In OF1 mice, a 107 day-old mouse, isolated since 51 days, acts as an "aggressor" when introduced into a group of 10 males or into a group of 10 females of the age of 51 days. This results in fights and flights in the males' group and in copulations in the females' group. In 31 experiments, each performed on a total of 40 males and 40 females, it was observed that an acute DL50 hypoxia (inhalation of nitrogen) provokes a mortality significantly (p less than 0.001) higher in the male "aggressors" (95.16%) than in the groups of 10 aggressed mice (mortality: 64.26% for the males' groups and 52.65% for the females groups). Besides, compared to control groups without male "aggressor", the introduction of the male congener significantly (p less than 0.001) increases the acute hypoxic mortality in the females' but not in the males' groups.

Acute Disease↗
PubMed1978

Hypoxia survival variations in male and female mice as functions of chronological and environmental factors.

The inhalation by mice for 20 min of 5.5% oxygen in nitrogen, performed 29 times over 40 months, causes a mortality of 49.81%. Correlation coefficients were calculated between hypoxia mortality and different parameters: environmental--lighting, temperature, hygrometry, barometric pressure, biological--sex, age, body weight; and chronological--circadian, circannual, pluriannual. Partial correlation coefficients eliminate several interrelationships and finally point out the statistical significance of transfer from dark to light (p less than 0.001), of circadian (p less than 0.05), and of circannual (p less than 0.01) hypoxic mortality variations. Moreover, a significant (p less than 0.001) sex-related difference of mortality (males: 56.94%; females : 41.14%) was observed, independently of the environmental and chronological parameters studied.

Age Factors↗
PubMed1977

[Sexual cycle period and resistance of mice to acute experimental hypoxia].

Variations of survival to an acute hypoxia (nitrogen) were studied, in 200 females, OF1, SPF mice, 72 days old, in groups of 10, at different periods of their estrus cycle, which were evidenced by vaginal smears. In mice which were in diestrus since 3-4 following days, the hypoxic survival (27.27%) was statistically less than in mice which were in estrus (58.00 %) or at the beginning of the diestrus (53.85 %).

Animals↗
PubMed1976

[Demonstration in Japanese quails of genetic differences in survival from hypoxia].

164 quails (Coturnix coturnix japonica; 94 males and 40 females), 27-55 days old and belonging to 9 families, each family being issued from a different couple of parents, were submitted to an acute nitrogen hypoxia which resulted in an overall mortality of 43.29%. The fact that a high statistically significant (p less than 0,001) heterogeneity was pointed out in these different families supports the existence of a genetic component of resistance towards hypoxia.

Animals↗
PubMed1976

Recent advances in investigations of toxicity of automotive exhaust.

The influence of auto exhaust on man's health is difficult to gauge considering the intricacy of human environmental urban stresses and particularly of other air polluting (industrial, domestic) emissions. Epidemiological surveys made in road tunnel employees and in traffic officers have not demonstrated specific effects and have often been complicated by cigarette smoking as a factor. Long-term animal experiments run mostly on small rodents give evidence of little effect of the pathological actions of dilutions such as those encountered in high polluted cities. However the acute toxicity of gasoline exhaust emission is well known and mostly due to carbon monoxide. Considering the different types of cycles and operating conditions of vehicles (gasoline and diesel), auto exhaust gases constitute no more a chemical entity than they show, a definite toxicity. A great number of substances that they contain (nitrogen oxides, aldehydes, antiknock additives, heavy metals, possible catalysts are highly toxic as shown by in vivo and in vitro (mutagenic) tests. Interactions of the components are for the moment ignored or poorly understood. Besides, the evolution of the physicochemical properties and natures of the auto exhaust emission in the gaseous biotope of man under determined conditions of ultraviolet irradiation, temperature, and hygrometry provoke the formation of secondary products such as oxidants and ozone. Several experiments show clearly that irradiation increases the toxicity of auto exhaust significantly. For these reasons, geographical, meteorological, and chronological (circadian and seasonal) factors should be taken into consideration, especially with regard to emission standards.

Air Pollution↗
PubMed1975

[Influence of recent modification of behavioral relationships of male and female OF1 mice on resistance to nitrogen or carbon monoxide hypoxia].

A decrease of resistance to hypoxia is obtained in OF1 mice, 24 hours after an hyperactivity resulting from a grouping by 13 of male or female mice previously isolated. Besides, this decrease is statistically significant in an acute nitrogen hypoxia but not in an acute carbon monoxide poisoning. In both hypoxias, in mice of same age the males are less resistant than females.

Age Factors↗
PubMed1975

Biorhythms in toxicology and pharmacology. I. Generalities, ultradian and circadian biorhythms.

According to their periods, rhythms can be classified in ultradian (period inferior to one day), circadian (period equal to one day) and infradian (period superior to one day). Different biorhythms of endogenous origin are modified mostly relatively to their amplitude by definite doses of the effects of pharmacological or toxic agents. Circadian variations of the effects of drugs, of the toxicities of gases as well as circadian modifications of the reactions to different stresses and agressions have been demonstrated amply in animals (mostly nocturnal rodents) and sometimes in man. In a general way reactions are more rapid and more marked in the active period where enzymatic reactions show a peak activity corresponding to a maximal energy output than during the rest and sleep periods.

Adrenocorticotropic Hormone↗
PubMed1975

Biorhythms in toxicology and pharmacology. II. infradian biorhythms and general discussion.

In man circaseptidian (weekly) rhythm has been established in certain employements where a delayed pulmonary allergic reaction is observed. Circatrigintan (monthly) rhythms related to the biological effects of the rotation of the moon around the earth or of the rotation of the sun around its axis have not been definitely pointed out in man. The demonstration of a circannual (seasonal) biorhythmicity of responses to drugs and toxins requires long runs of observations (5-7 years). However circannual, as well as infrannual rhythms, should not be dismissed as they are consequences of biometeorological factors the actions of which at least for temperature on toxic reactions are admitted. Besides the influences of endogenous factors such as sex and aging perturbate the endocrinological modulations of these biorhythms and complicate the scope of such a research. The cyclic action mechanism of therapeutic and toxic agents appears to be a direct impact on intrinsic enzymatic rhythms of different periods entrained by the physical, chemical and principally psychophysiological factors of man's environment.

Animals↗