Growth failure after recurrent fever in young guinea pigs.

Infection causes fever and suppression of appetite, a combination of effects which threatens normal growth in infected children. We have used an animal model to study the effects on growth of recurrent simulated Gram-positive bacterial infection. After weaning, 10 guinea pig pups underwent surgery under general anaesthesia for the implantation of temperature-sensitive radiotelemeters and thereafter were assigned to receive intramuscular injections of either 50 microg/kg muramyl dipeptide (MDP), or sterile saline. During a 30-day period corresponding to their rapid growth phase, the pups were given eight injections. MDP resulted in fevers of about 1.5 degrees C on each occasion, but no significant change in body temperature occurred after saline injections. Food intake was suppressed during each febrile episode such that 24-h intake was significantly lower on days of injections of MDP, compared to days between MDP injections in the same animals, and compared to that of animals injected with saline. The rate of weight gain of the MDP-injected guinea pigs was significantly lower than that of the control group and failed even to achieve a rate similar to the saline-injected group in their more adult-like growth phase. Plasma zinc concentration was significantly lower in MDP-compared to saline-injected animals sampled 8 days after the last injection. Our results show that recurrent fever during the growth phase of young guinea pigs results in irreversible growth failure, and that reduced food intake on days when the animals were febrile was at least partly responsible for this reduced rate of growth.

Feto-maternal relationships in goats during heat and cold exposure.

Maternal and fetal body temperatures were measured in five Boer goats, of mean mass 64 +/- 8 kg, using temperature-sensitive radiotelemeters implanted intra-abdominally. Body temperatures were recorded every 5 min. Throughout the last month of gestation, fetal temperature was approximately 0.6 (o)C higher than that of the mother, in normal laboratory conditions (ambient air temperature: 21-24 (o)C). This feto-maternal temperature difference between the goat fetus and its mother is similar to that found in other mammals, including sheep. When the pregnant goats were subjected to short-term heating and cooling, the difference between maternal and fetal body temperatures changed. Thus the mean difference between fetal and maternal body temperatures decreased from 0.4 to 0.2 (o)C during 2 h of heating, while it widened from 0.3 to 0.7 (o)C during 6 h of cooling. These data support the idea that the fetus is thermally protected from excursions of body temperature during changes in the mother's thermal environment. Reports of goat stock losses and abortions during cold spells in their natural habitats may be the result of more severe and/or prolonged cold exposures that not only adversely affect fetal or maternal body temperature, but also influence other aspects of metabolism. Experimental Physiology (2001) 86.2, 199-204.

[Reproducibility of measurements of arterial pressure and heart rate during exercise test: its significance and application]. / Reproductibilité des mesures de la tension artérielle et de la fréquence cardiaque lors de l'épreuve d'effort. Intérêt et applications.

The authors report their findings from a study of the reproductibility of measurements of blood pressure and heart rate both at rest and during exercise (work on a bicycle ergometer) in 19 patients who were tested on two occasions with a mean interval of 9.8 days. A study of the correlations, of variability, and of the findings on applying Student's "t" test, have led us to the conclusion that these parameters are more reproduceable on exercise than at rest, and become increasingly reproduceable as exercise increases. These conclusions support the use of an induced hypertension test under exercise.