Influence of circadian rhythm on 41.8 degrees C whole body hyperthermia induction of haematopoietic growth factors

The immune-endocrine interaction varies with the duration of the inflammatory process in cardiac surgery patients

The present study investigated the perioperative course of cytokine release and hypothalamic-pituitary-adrenal (HPA) axis activation in relation to the duration of the inflammatory response in cardiac surgery patients. Twelve male patients scheduled for elective coronary artery bypass grafting surgery with cardiopulmonary bypass and general anaesthesia were divided into two study groups: group 1 (n=6) underwent surgery at 13.00 h+/-30 min, group 2 (n=6) at 08.30 h+/-50 min. Blood samples were collected preoperatively and up to the first postoperative day. Postoperatively, on the day of surgery, serum concentrations of the proinflammatory cytokines interleukin (IL)-6, IL-1beta and tumour necrosis factor (TNF)-alpha were not significantly different between the two groups, while blood concentrations of cortisol, adrenocorticotrophic hormone (ACTH) and beta-endorphin in group 2 patients were significantly higher than in group 1 patients. Postoperatively, on the day of surgery, ACTH and cortisol concentrations in group 1 patients were positively correlated to the blood concentrations of IL-1beta, IL-6 and TNF-alpha. By contrast, group 2 patients showed no significant relationship between cytokine release and activation of HPA axis at this time. Our results suggest that in patients undergoing cardiac surgery, the cytokine response is initiated before the HPA axis is fully activated. In the early postoperative period, cytokines appear to be involved in the activation of the HPA axis, while in the later postoperative period, high cortisol concentrations may inhibit the release of IL-6.

Inhibition and recovery of GM-CSF production in the lung after hyperthermia

The purpose of this work was to study the response that is invoked by hyperthermia in the production of Granulocyte-Macrophage colony-stimulating factor (GM-CSF) by the lung. Rats were heated regionally at chest area by a RF generator operating at 27.397 MHz for 1 h at various temperatures and then allowed to recover or repair in various periods of time after heat application. Lung tissue from these animals was then removed and cultured for the production of GM-CSF. GM-CSF was assayed by the production of colonies in the semi-solid agar cultures of bone marrow cells. Immediately after heat treatment hyperthermia had no significant effect on the production of GM-CSF by the lung. A delayed effect was observed about 3.5 h after heat treatment. This effect consisted of a temperature dependent decrease in GM-CSF production. The damage was recoverable and required 1-50 days of post heat treatment time for animals to reach normal level of GM-CSF production. The results suggest that in-vivo application of hyperthermia invokes temporary reduction in GM-CSF production by the lung, which has not been reported previously.