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Biomedical subjects

C Milhaud

Publications and source records attributed to C Milhaud.

13 recordsLinked to original sources
PubMed1996

Hormonal response to restraint in rhesus monkeys.

The purpose of this study was to characterize the hormonal responses to a restraining system in four adult male rhesus monkeys (Macaca mulatta) in preparation for a spaceflight project. After the monkeys were accustomed to food and water (Phase I), blood-volume-regulating hormones were measured during three phases: 10 days in a metabolic cage (Phase II), 16 days sitting in a restrained position in a specially designed metabolism chair (Phase III) and 10 days in metabolic cage (Phase IV). An increase of active renin (30%) and vasopressin (25%) was observed at the end of Phase III. A decrease of atrial natriuretic peptide (ANP), urodilatin, and sodium excretion occurred during the first days of Phase III. Catecholamines were unchanged. A dramatic increase (tenfold) in urinary excretion of growth hormone occurred during all of Phase III and at the beginning of Phase IV. These findings are similar to those found in man during isolation inactivity and during confinement stress.

Aldosterone↗
PubMed1993

The effects of a 5-month physical training on iliac bone morphology in monkeys.

The present study was designed to provide data on the effects on bone of 5 months of daily exercise in nonhuman primates. The subjects were five male rhesus monkeys with mature skeletons with a body mass of 8-10 kg. The exercise schedule selected to provide endurance training was a daily continuous 1-h climbing task. An iliac crest bone biopsy was performed prior to and at the end of the physical training. The histomorphometric bone study was based upon bone mass and bone cell activity measurements made on nondecalcified bone slides, using trichromic and fluorescent labelling techniques. Results showed a decrease in bone formation, resulting in reduced bone mass at the end of the 5 months. This effect is suggested to be related to the unphysiological climbing regimen imposed on these animals which are naturally used to short periods of rapid exercise. From these investigations it was concluded that even if it is well tolerated, long-term physical endurance training can induce bone loss in primates. Further investigations are needed to determine with accuracy the relationships between bone physiology and physical exercise, and particularly with regard to its type, intensity and duration.

Animals↗
PubMed1992

Bone mass and bone cellular variations after five months of physical training in rhesus monkeys: histomorphometric study.

Five Rhesus Monkeys (Macaca mulatta), a suitable nonhuman model, performed 5 months of rope-climbing exercise. Duration of the training sessions was progressively increased to reach 1 hour/day after 1 month of training and was maintained until the end of the experiment. Bone mass parameters, bone resorption, and bone formation activity were measured by histomorphometric analysis on iliac crest bone biopsies before and after the experiment. Mineral apposition rate was measured in cortices and trabecular bone after double calcein labeling. Five months of rope-climbing exercise had determined a significant decrease of bone volume with a slight decrease of the number and thickness of trabeculae. This might induce an alteration of biomechanical properties of bone. These architectural modifications were associated with a nonsignificant decrease of bone resorption activity. But the main effect of training was an important decrease of bone formation activity without change of the mineral apposition rate. Endurance exercise at low intensity has determined a decreased bone turnover with osteoblastic depression. This animal experiment points out that exercise modalities might be important in the bone response to training and should be carefully defined for preventive use in humans.

Animals↗
PubMed1990

Behavioral effects induced by beta CCE in free or restrained rhesus monkeys (Macaca mulatta).

Behavioral effects of the IV injection of beta carboline carboxylic acid ethyl ester (beta CCE) were studied in chair-restrained rhesus monkeys and in rhesus monkeys freely moving in their cages. Observations made during the administration of increasing doses of beta CCE (0.5, 1 and 2 mg/kg) evidence behaviors reflecting a state of anxiety. The similarity of results obtained under the two experimental conditions excludes a potential effect of restraint on the behavioral expression of effects induced by the administered molecule. Convulsions observed in three subjects out of twelve should call for great caution when using this molecule.

Animals↗
PubMed1990

Electroencephalographic effects of modafinil, an alpha-1-adrenergic psychostimulant, on the sleep of rhesus monkeys.

An electroencephalographic (EEG) study on the rhesus monkey, primate model of human sleep, showed the significant wakening effect of a new psychostimulant, Modafinil. The first experiment, with single administration of three increasing doses of Modafinil (3, 6, and 12 mg/kg), was to determine the efficient threshold dose; the second experiment, with repeated administration of 22.5 mg/kg during 4 days, was to determine whether continuous wakefulness could be obtained without apparent behavioral disorders. Results of the first experiment showed a wakening effect above 6 mg/kg, but 12 mg/kg induced a sharp wakening effect with a significant decrease in all sleep stages. The second experiment induced important insomnia in all subjects for 4 days and 4 nights. No behavioral disorder was observed. Modafinil has a wakening effect at the dose of 6 mg/kg in rhesus monkeys and induces quasicontinuous wakefulness for 4 total days and nights with daily administration of 22.5 mg/kg, with no behavioral disorders. Modafinil should therefore find interesting applications in sleep disorder treatments.

Animals↗
PubMed1990

Changes in electrical impedance of the vaginal medium during the menstrual cycle of female rhesus monkeys (Macaca mulatta).

Changes in electrical impedance of the vaginal medium during the menstrual cycle were recorded in female Rhesus monkeys using electrical probe and were correlated with estradiol-17 beta and progesterone plasma concentrations. A gradual decrease in impedance was observed during the follicular phase, the lowest values being observed between days 12-17 of the cycle. Impedance increased again during the first third of the luteal phase until day 21. The reversal of the impedance gradient's sign was nearly concomitant with the appearance of a detectable plasma progesterone concentration. These results support the use of vaginal impedance measurements as a help for the diagnosis of the periovulatory time in the female Rhesus monkey.

Animals↗
PubMed1990

Five months of daily standardized exercise for sedentary monkeys.

A system to physically exercise rhesus monkeys is described, based on their natural capacity to climb. It is composed of an enclosure where a motor-driven rope is continually going down. The two stage training to this task is easily performed. The total work of each run, evaluated with the weight of the animal and the distance climbed, may be very stable. It was used to provide five sedentary monkeys with daily physical training for five months.

Animals↗
PubMed1988

A new technique for iliac crest biopsy in rhesus monkeys for use in weightlessness experiments: some results of ground studies.

The similarity of major physiological functions between man and monkey make non-human primates a suitable model, especially for experiments in weightlessness. Bone tissue of rhesus monkeys can easily be analysed by histological techniques in order to appreciate the effects of hypogravity upon the skeletal system. A technique for iliac crest biopsy has been developed in a laboratory. It is to be used on rhesus monkeys used in various experimental situations, and especially after exposure to the space environment.

Animals↗
PubMedDate not supplied

French research program on the physiological problems caused by weightlessness. Use of the primate model.

The need to acquire a better knowledge of the main biological problems induced by microgravity implies--in addition to human experimentation--the use of animal models, and primates seem to be particularly well adapted to this type of research. The major areas of investigation to be considered are the phospho-calcium metabolism and the metabolism of supporting tissues, the hydroelectrolytic metabolism, the cardiovascular function, awakeness, sleep-awakeness cycles, the physiology of equilibrium and the pathophysiology of space sickness. Considering this program, the Centre d'Etudes et de Recherches de Medecine Aerospatiale, under the sponsorship of the Centre National d'Etudes Spatiales, developed both a program of research on restrained primates for the French-U.S. space cooperation (Spacelab program) and for the French-Soviet space cooperation (Bio-cosmos program), and simulation of the effects of microgravity by head-down bedrest. Its major characteristics are discussed in the study.

Adaptation, Physiological↗