Circadian temperature rhythms in rabbit pups and in their does.

Circadian rhythms of mammals are generated endogenously, the master oscillator system residing in the suprachiasmatic nuclei (SCN). Previous experiments have indicated that the rabbit has a feeding entrainable circadian oscillator (FEO) which is supposed to be of greatest importance during the early infancy of the rabbit. Here we report the course of telemetrically monitored core body temperature of rabbit pups and of their does. Temperature increased from 37.6+/-0.3 degrees C on day 2 to 39.5+/-0.1 degrees C on day 28 of life. The pups showed a 24 h temperature rhythm even during their first days of life. Temperature increased 2 1/2-3 h prior to nursing for 0.4-0.8 degrees C and rose for an additional 0.4-0.6 degrees C immediately after milk ingestion. The anticipatory, but not the postprandial component persisted when nursing was skipped twice. The persistence of a rhythm in the absence of any entraining agent is crucial for its endogenous generation. In the doe, the core body temperature gradually decreased during the last 2/3 of pregnancy. During parturition it steeply rose for 1.5-1.7 degrees C and attained a plateau of 39.7+/-0.2 degrees C during lactation. The circadian rhythm persisted during the whole course of pregnancy and lactation. Thus, in the rabbit an endogenous, feeding entrainable circadian oscillator appears to operate from the first days of life. It is of functional significance in that it alerts the pup in time so that it is able to utilize the singular short presence of the doe for maximal milk intake.

Circadian thermoregulation in suckling rabbit pups.

The rabbit pup is well suited to track the age-dependent development of periodic thermoregulation during the suckling period. Since the litters are regularly nursed once per day for a total of 3 to 4 min, an exogenous, metabolic, nonphotic periodic variable is supposed to have an impact on the 24-h rhythm of body temperature. The authors monitored the course of core body temperature during the suckling period of 20 pups by means of a transmitter implanted intraperitoneally on day 3 postpartum. The 24-h mean rose from an average of 37.8+/-0.3 degrees C on day 4 of life to 39.5+/-0.2 degrees C at weaning on day 27, for 2 out of 20 pups, and day 28, for 18 out of 20 pups. In constant dim illumination, the pups exhibited a 24-h rhythm even on postnatal day 4, which consolidated around days 5 to 7. The rhythm consisted of a significant anticipatory rise of 0.4 to 0.6 degrees C above the respective 24-h mean commencing 2.5 to 3.5 h prior to nursing. Milk intake was followed by a further increase of temperature for an additional 0.3 to 0.6 degrees C. Then the temperature dropped for 1.2 to 1.5 degrees C within 1 to 3 h and returned to average 3 to 5 h later. During a 48-h fast, the rhythm continued to exist, though in a modified shape: the anticipatory component persisted almost unchanged; a further elevation of temperature, however, did not occur. Thus, the anticipatory component apparently is generated endogenously and the second surge represents an exogenous suckling-induced, thermogenic peak. When maternal nursing was advanced for 15 min/day for a total of 5 h, the temperature rhythm of the pups followed the shift of the zeitgeber in parallel. These data confirm the assumption that a circadian rhythm exists during the first postnatal days of the rabbit and that this rhythm is entrained by the 24-h nursing rhythm. The authors suggest that the biological significance of a feeding entrainable oscillator (FEO) in the rabbit might be to activate the pups prior to the periodic nursing visit of the rabbit doe. Thus, the pups are prepared to quantitatively use the one and only short nursing episode per day for maximal milk ingestion.

Patient education and emergency room visits.

Patients visit emergency rooms for urgent and non-urgent care. Because emergency room visits are more costly than visits to primary care clinics and are less likely to involve preventive care, third party payers and institutions have always tried to shift patients away from the emergency room and towards primary care clinics where appropriate. Hypothesizes that an intervention based in an adult primary care clinic might enable this, especially if it involved patients who used both the clinic and the emergency room. Surveys patients to determine why they used the emergency room and to identify barriers to using the primary care clinic instead. Based on the survey results, an intervention was developed to facilitate use of the primary care clinic. Discusses the methodology used in the survey and analyses results. Concludes that it is difficult to change patient behaviour to fit the demands of the health care system. Possibly, it would be better to change the system to fit the behaviour patterns of the patients.