Biomedical subjects

Gérard Dewasmes

Publications and source records attributed to Gérard Dewasmes.

2 recordsLinked to original sources

PubMed2006

Thermoregulatory control of feeding and sleep in premature infants.

OBJECTIVE: The aim of the present study was to test the thermoregulatory feeding control hypothesis in sleeping, premature infants. RESEARCH METHODS AND PROCEDURES: In premature infants, the energy supply from food intake is crucial for (in order of importance): organ operation, body homeothermia, and optimal growth. The Himms-Hagen model of thermoregulatory feeding control involving activation of heat production by brown adipose tissue (BAT) was formulated on the basis of work in (awake) rats. This hypothesis has also been put forward for the human neonate, which can also use BAT to produce metabolic heat. According to the model, feeding episodes occur during a transient increase in body temperature. Feeding is initiated by a dip in blood glucose concentration after sugar uptake by activated BAT. RESULTS: In 14 neonates (bottle-fed on demand), food intake always took place during an increase in skin temperature (+0.19 +/- 0.21 degrees C). Awakening occurred 18 +/- 17 minutes after the minimum skin temperature level had been reached. When feeding time was imposed, feeding was not necessarily situated during an increase in skin temperature, and the sleep duration after food intake increased significantly (+43%). This could be considered as an adaptive response to the short-term sleep deprivation and/or stress elicited by an imposed feeding rhythm. DISCUSSION: The validity of the model supports the use of on-demand feeding in neonatal care units, in accordance with the infant's physiological body temperature oscillations.

Adipose Tissue, Brown↗

PubMed2003

Liver temperature during sleep.

STUDY OBJECTIVE: The liver, like brown adipose tissue, is an important source of nonshivering thermogenesis. We tested the hypothesis that the thermal state of the liver is preserved during slow wave sleep but deteriorates during paradoxical sleep. METHODS: Twelve adult male Wistar rats were equipped with electrodes and thermistor probes--which measured cortical (Tco), interscapular brown adipose tissue (Tibat), and liver (Tl) temperatures--for thermal and sleep studies. Six rats were exposed to thermoneutral (24 degrees C) and 6 to low (9 degrees C) ambient temperature. Isolated paradoxical sleep episodes preceded and followed by more than 3 minutes of wakefulness or slow wave sleep were analyzed. The Tco, Tibat, and Tl levels were also assessed during the slow wave sleep that preceded each isolated paradoxical sleep episode. RESULTS: During slow wave sleep, the Tibat and Tl were clearly higher in rats exposed to the cold than in those exposed to the thermoneutral condition (< 1 degrees C). During paradoxical sleep, however, these 2 temperatures decreased in rats exposed to the cold condition, and the changes observed for Tco were completely inversed. CONCLUSIONS: These results support the hypothesis that the thermal state in the liver of rats deteriorates during paradoxical sleep and suggest that nonshivering thermogenesis in the liver contributes to the defense of global thermal homeostasis in the sleeping endothermic organism, especially during slow wave sleep.

Animals↗