380 Burns (1985) 11.380-382 Printedin Great Britain

Abstracts

CLINICAL STUDIES

Blister fluid opsonins The opsonic activity of blister fluid from burned patients was tested against Staph. aureus and Ps. aeruginosa. As blister fluid could not opsonize Pseudo- monads a series of repletion experiments indicated that this opsonic defect was not due to the presence of inhibitors but to a lack of normal serum factors. The opsoninopathy was due to local consumption of com- plement components in the burn wound. Blister fluid also depressed neutrophil chemotaxis and random migration. Thus in the region of a burn blister both cellular and humoral immunity is disturbed.

Deitch E. A., Dobke M. and Baxter C. R. (1985) Failure of local immunity. A potential cause of burn wound sepsis. Arch. Surg. 120, 78.

Serum enzyme changes Various enzyme levels were measured in 5 patients with burns covering between 20 and 60 per cent of the body surface area. Early increases in lipid peroxide levels in serum were followed by rises in the levels of glutamate oxalacetate transaminase, glutamate pyruvate trans- aminase, alkaline phosphatase and lactate dehydro- genase. It is suggested that the lipid peroxide damages the cell membranes of various organs, particularly the liver, thereby allowing the leakage of the other enzymes into the circulation.

Hiramatsu M., Izawa Y, Hagihara M. et al. (1984) Serum lipid peroxide levels of patients suffering from thermal injury. Burns 11, 111.

Selenium depletion The selenium levels in plasma and erythrocytes and the 24 h urinary excretion of the element were measured in 17 burned patients and 191 healthy control subjects. The selenium intake of the burned patients was lower than the intake of the control subjects when total parenteral nutrition or tube feedings were used as primary nutrient sources but was comparable to the control intake when burned patients consumed oral diets. Serial measurements in blood and urine at 10 day intervals post burn showed reduced plasma, and erythrocyte levels and a reduced urinary excretion of selenium. The erythrocyte glutathione peroxidase levels were also reduced. These reductions suggest a state of selenium depletion in spite of an exogenous

selenium intake which was within the range recom- mended for healthy adults. It remains to be determined whether increased selenium administration can modify these findings.

Hunt D. R., Lane H. W., Beesinger D. et al. (1984) Selenium depletion in burn patients. J. Parent. Entr. Nutr. 8, 695.

Neutrophil chemotactic activity Random mobility and chemotactic responses were measured in polymorphonuclear neutrophils isolated from 14 patients with burns covering between 22 and 75 per cent of the body surface area. In 8 of the patients who showed no evidence of systemic infection the neutrophil migratory functions fell below control values between 4 and 30 days after injury. The loss of chemotactic response to activated serum was associated with rises in immunoreactive plasma C3a and C5a.

Solomkin J. S., Nelson R. D., Chenoweth D. R. et al. (1984) Regulation of neutrophil migratory function in burn injury by complement activation products. Ann. Surg. 200, 742.

Fatty acid turnover The turnover of palmitate using r3C-labelled palmitic acid was measured in 9 patients with burns covering between 19 and 52 per cent of the body surface area. In these patients the plasma levels of glucose, insulin, glucagon, adrenaline and noradrenaline were signi- ficantly elevated compared with values in normal individuals. Plasma palmitate and free fatty acid concentrations were not different from control values, but palmitate flux and free fatty acid turnover calcu- lated therefrom were significantly elevated compared to the control rates. While palmitate turnover was significantly correlated with plasma palmitate concen- trations and with the percentage body surface area burned there was no relationship between palmitate tlux and the circulating levels of adrenaline and noradrenaline. The lipolytic effect of these catechola- mines thus needs further study.

Galster A. D., Bier M., Cryer P. E. et al. (1984) Plasma palmitate turnover in subjects with thermal injury. J. Trauma 24, 938.

ANIMAL STUDIES

Nitroblue tetrazolium and muscle damage The ability of normal muscle to reduce colourless

Abstracts 381

nitroblue tetrazolium (NBT) to blue formazin was used both experimentally and clinically to differentiate between normal, ischaemic and necrotic muscle tissue, the latter two tissues being almost unable to carry out this reduction. Degrees of tissue damage were assessed by the amounts of muscle tissue that were required to reduce a standard amount of NBT. All tissues that could react with NBT were histologically viable. Metabolically active or viable muscle libres are rich in dehydrogenase enzymes which perform the NBT re- duction. This NBT reduction technique identified non-viable tissue and clearly showed the even distribu- tion of muscle damage induced by the passage of electricity. The test may be carried out during an operation on fresh muscle biopsies.

Hunt J. L. and Heck E. L. (1984) Identification of nonviable muscle in electric burns with nitroblue tetrazolium. J. Surg. Res. 37, 369.

Burned tissue induced suppression The ability of burned tissue to induce immuno- suppression was tested in mice using the technique of dinitrofluorobenzene sensitization of ear tissue. A deep steam burn covering 20 per cent of the body surface area (BSA) was profoundly immunosuppressive, par- tial thickness skin loss burns and deep burns involving less than IO per cent BSA were not significantly immunosuppressive. Transfer into normal mice of burned skin equivalent in size to a 20 per cent BSA burn eschar induced marked immunosuppression in contrast to the lack of effect caused by smaller amounts of burned skin or larger amounts of unburned skin or normal or burned liver tissue. Mice receiving a very high temperature (300°C) dry burn were only slightly more suppressed than mice receiving the steam burn.

For reasons that are not yet understood normal immunity was preserved in burned mice which received daily applications of cerium nitrate to the wound for 7 days, whereas application of other topical agents commonly used in burn treatment did not preserve immunity.

Hansbrough J. F., Zapata-Sirvent R., Peterson V. et al. (1984) Characterization of the immunosuppres- sive effect of burned tissue in an animal model. J. Surg. Re.s. 37. 383.

New immunomodulators The effectiveness of two new immunomodulators has been studied in guinea-pigs with deep burns covering 30 per cent of the body surface area. The animals were given either saline or 0.3 mg/kg thymopentin or 0.3 mg/ kg of compound CP 46665. Neutrophils, macrophages and serum samples were obtained from the animals and tested for their ability to phagocytose and kill Ps. aeru- ginosa and the serum was tested for its ability to opsonize E. co/i. Thymopentin improved neutrophil function on post-burn days 2 and 4 and improved macrophage function on post-burn day 4. Compound CP 46665 improved both macrophage function and opsonization on post-burn day 2.

Waymack J. P., Gonce S., Miskell P. et al. (1985) Mechanisms of action of two new immunomodulators. Arch. Surg. 120. 43.

Tissue and serum amino acid levels Rats with scalds covering 25 per cent of the body surface area and receiving only 5.6 kcal per 100 g body weight per day and no nitrogen containing compounds showed mean daily nitrogen losses of -0.27-1-0.3 g. Compared with the results in normal growing rats this nitrogen catabolism significantly reduced the total free amino acid content of muscle and liver. In the scalded rats the plasma amino acid concentrations were slightly increased whereas the muscle glycine content dropped significantly. The glutamine concentrations fell slightly. There were significant increases in plasma and muscle contents of phenylalanine and branched chain amino acids. All these changes except the glycine content of muscle are comparable to the results obtained in burned patients, suggesting that this burned rat model is a suitable model for studying aspects of protein metabolism in burned patients.

Karner J., Roth E., Funovics J. et al. (1984) Effects of burns on amino acid levels in rat plasma. liver and muscle. Burns 11. 130.

Dietary fat requirements Intragastric tube feeds containing 0, 5, 15, 30 and 50 per cent of non-protein calories were given to 45 guinea-pigs with full thickness skin loss burns covering 30 per cent of the body surface area. Total energy given, protein content and composition, total volume, vitamin and mineral content were constant in all animals. By 2 weeks after burning, body carcass weight and muscle mass were greatest in the 0 and 5 per cent lipid groups and least in the 30 and 50 per cent lipid groups. Serum transferrin concentration was highest in the 5 and 15 per cent lipid group and lowest in the 30 and 50 per cent lipid groups. Total nitrogen content in muscle and cumulative nitrogen balance were best in the I5 per cent lipid group. Liver fat content was greater in the 0 and 5 per cent lipid groups than in the 15 and 30 per cent groups. Thus dietary lipid levels between 5 and 15 per cent of non-protein calories seem optimal for the nutritional support of burned guinea- pigs. Whether such inputs are optimal for burned patients remains to be determined.

Mochizuki H., Trocki 0.) Dominioni L. et al. (1984) Optimal lipid content for enteral diets following ther- mal injury. J. Parent. Entr. Nutr. 8, 638.

Healing of burn and freeze injuries The healing of high temperature (100°C) and very low temperature (- 196°C) injuries differs since burn wounds contract whereas freeze injuries do not. Myofibroblasts do not appear to be involved in this difference since they can be found uniformly distri- buted in the granulation tissue of the healing burn and in the islands of granulation tissue between residual connective tissue fibres in the healing freeze injury. The