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HART1has referred to the potential uses of radar in geodesy and photogrammetry. The War Office has now granted permission to publish details of geodetic observations made in Italy by radar during May–June 1945. The general principle of these observations was that an aircraft, a medium bomber with an operational speed of 230 miles per hour, flew a circular arc centred upon a ground radar beacon while the distance from a second beacon was recorded at regular (1–2 sec.) intervals. The geodetic distance between the two beacons was then computed from the radius of the arc and the minimum recorded distance from the second beacon by correcting for altitude and refraction.

We have generated a series of myb transformed myeloid haematopoietic cell (MTHC-D) lines that can be induced to differentiate into macrophage-like or dendritic cells upon exposure to TNF in combination with IL-4 or interferon gamma. Substractive cDNA libraries made between parent and mature cells or between the two alternate differentiated cell types confirm the lineage relationships of these cells. The two mature cell types may represent different stages of dendritic cell maturation since the DC phenotype is rapidly converted to the macrophage phenotype by the addition of IL-4. Some clones of MTHC fail to differentiate in response to TNF and instead undergo apoptosis (MTHC-A). Subtractive cDNA libraries suggest that MTHC-A cells are more closely related to granulocytes than they are to macrophages. Engagement of TNF receptor type I is sufficient to induce differentiation, but both type I and type II receptors must be engaged to induce apoptosis. Several families of genes that are differentially expressed in ‘macrophage’ and dendritic cells have been isolated, including a large number of novel genes, some of which will be discussed.

To determine if general anaesthesia alone or in conjunction with surgery alters body protein turnover, we studied six healthy, unpremedicated females undergoing elective total abdominal hysterectomy. Changes in protein metabolism, synthesis and breakdown were estimated by an isotope dilution technique using a continuous infusion of the stable isotope tracer, L-[1–13C]leucine, before anaesthesia (4 h), during anaesthesia alone (1 h), during anaesthesia and surgery (1 h) and in the recovery period (2 h). General anaesthesia comprised thiopentone, pancuronium, enflurane (1 MAC) and oxygen-enriched air. An isotopic steady state in plasma 13C-α-ketoisocaproate (13Cα-KIC) and expired 13C-carbon dioxide were obtained during the four periods. Collections of plasma and expired air were made during the steady state periods and plasma α-KIC enrichment measured to indicate precursor pool labelling from which leucine flux (equal to protein breakdown in the post-absorptive state) and oxidation were calculated, and whole body protein synthesis was derived. Whole body protein breakdown did not change with anaesthesia, but decreased with both surgery and during the acute recovery period (P < 0.05). Protein synthesis did not change with anaesthesia and surgery, but decreased significantly after surgery (P < 0.05).

We have studied the effect of intraoperative body heat conservation and 24-h thermoneutrality on postoperative whole body protein turnover using stable isotope methodology in a group of elderly patients undergoing colorectal surgery for rectosigmoid adenocarcinoma. Two groups of eight patients were studied. One group (control, or cold) received routine intraoperative and postoperative care. All patients in the second group (warmed) were maintained at normothermia during anaesthesia and surgery; these patients were nursed after surgery in a warm room (ambient temperature 28–30°C) for a period of 24 h. General anaesthesia, surgical care and nutritional support were similar in both groups. A constant nutritional intake, based on nitrogen 0.1 g kg−1 day−1 and energy 20 kcal kg−1 day−1, was provided orally for 7 days before surgery and i.v. after operation for 4 consecutive days. Whole body protein breakdown and synthesis, as assessed by stable isotope methodology, increased significantly 2 and 4 days after surgery in both groups (P<0.01), but the increase in protein breakdown in the warmed group on day 2 was significantly less than that in the cold group (P<0.05). The increase in leucine oxidation in the warmed group on the 2nd day after surgery was not significant, and was less than the increase observed in the cold group (P<0.05). However, by the 4th day, leucine oxidation was enhanced significantly in both groups (P<0.01). The cumulative urinary nitrogen excretion over 4 days and the loss of fat-free mass, as measured by total body potassium 7 days after surgery, were significantly less in the warmed group compared with the cold group (P<0.05). Urinary excretion of adrenaline and cortisol after surgery was significantly less in the warmed group compared with the cold group (P<0.05). Thus the attenuated whole body protein breakdown and ami no acid oxidation observed in the warmed group after surgery might be explained, to some extent, by the specific hormonal suppression achieved with thermoneutrality.

We have studied the effect of intraoperative and postoperative (24 h) extradural block with local anaesthetic on whole body protein turnover (stable isotope methodology) and urinary excretion of urea nitrogen, adrenaline, noradrenaline and cortisol in a group of well nourished elderly patients undergoing colorectal surgery who received a constant nutritional intake before (7 days) and after (4 days) surgery. One group (control, n = 8) received routine anaesthetic and surgical care. Patients in the test group (extradural, n = 9) received extradural bupivacaine, and sensory block (T4-S5) was maintained during and after surgery for a period of 24 h. Whole body protein breakdown and aminoacid oxidation increased significantly after surgery in both groups (P < 0.05), but the increase in protein breakdown in the extradural group was significantly less than that in the control group. Urinary excretion of urea nitrogen, adrenaline and noradrenaline increased in the control group after surgery, whilst the increase in the extradural group was very small. In contrast, urinary excretion of cortisol increased significantly in both groups after surgery. We conclude that extradural block maintained for 24 h after surgery significantly minimized postoperative protein breakdown without compromising whole body protein synthesis.