234 Bums(l99o)Vol. 16/No.3

ANIMAL STUDIES

Benefits of dietary structured lipids Rats with burns covering 30 per cent of the body surface received enteral nutrition through a gastrostomy containing 50Kcal of energy per day, 2 g amino acids per day and 40 per cent non- protein calories as lipid. The lipid source was either long-chain triglycerides (LCT) or medium-chain triglycerides (MCT), struc- tured lipid (SL) or a physical mix (PM) of the oils used in the structured lipid.

Burned rats receiving either SL or PM showed significantly higher daily and cumulative nitrogen balances and rectus muscle and liver fractional synthetic rates than those fed either LCT or MCT. Rats fed SL or MCI’ maintained higher serum albumin levels than rats fed either PM or LCT. Therefore protein anabolism is improved and protein catabolism is decreased when the diet contains structured lipid or a mix of structured lipids.

DeMichele S. J., Karlstad M. D., Bistrian B. R. et al. (1989) Enteral nutrition with structured lipid: effect on protein metab- olism in thermal injury. Am. ]. Clin. Nufr. 50, (6), 1295-1302.

Ented feeding liits gut bacterial translocation Guinea-pigs were given a large dose of Candida albbns intra- gastrically prior to receiving a SO per cent total body surface area burn. They were then fed a bolus liquid feed at 3 h or 12 h post- burn. At 24 h postbum these guinea-pigs and controls who were starved or only fed saline were killed and mesenteric lymph nodes and intestinal segments were collected. Blood levels of IgG, C, cortisol and albumin were also measured.

Compared with controls the animals fed at 12 h had reduced numbers of C. albiums in the mesenteric lymph nodes and in the ileum. Bolus feeding at 12 h was associated with lower cortisol levels than bolus feeding at 3 h or in controls. Serum cortisol levels correlated positively with the extent of C. albicans translocation to the lymph nodes and negatively with C, levels regardless of diet- ary treatment.

moue S., Epstein M. D., Alexander J. W. et al. (1989) Prevention of yeast translocation across the gut by a single enteral feeding after burn injury. J Parent. Entr. Nufr. 13, (6), 565-571.

Smoke inhalation and enzyme stimulation Dogs with a smoke inhalation injury showed rises in pulmonary artery pressure, pulmonary vascular resistance and shunt fraction while the dynamic compliance fell. Within 5 min of smoke expo- sure lung angiotensin-converting enzyme declined without any change in the serum content of this enzyme. The lung content of plasminogen activator had dropped by I h after injury. Plasma angiotensin levels increased within 30 min of injury without evi- dence for systemic hypertension.

Clark W. R., Molteni A., Nieman G. et al. (1989) Effect of acute smoke inhalation on angiotensin converting enzyme,

plasminogen activator and angiotensin II in the dog. Ann. C/in. Lab. sn’. 19,(6). 452456.

Hypothalamic control of temperature regulation Varying the temperature around the preoptic anterior hypothala- mus of control and burned rats modified their responses to varying ambient temperatures around their bodies. When the ambient temperature was 22°C there was a significant increase in therrno- sensitivity of the hypothalrnus for both control and burned rats compared with the thermosensitivity at 32'C. The threshold tem- perature for heat production was shifted upwards both by a lower ambient temperature and by burns. The reference temperature for heat production was also shifted to the right by burn injury which enhanced the ability of the animals to meet the stress of hyper- metabolism. There were no significant differences in thermoregu- lation of control or burned animals when the ambient temperature was 32°C.

Caldwell F. T., Graves D. B., Wallace B. H. et al. (1989) Alteration in temperature reguiation induced by bum injury in the rat. J. Bum Cure Rehabil. 10, (6) 486493.

Treatment of heat-injured nerves Raising the temperature of short segments of the sural or posterior tibia1 nerves of rats to 45°C caused a partial conduction block. This block appeared to be irreversible without specific treatment. Top- ical application of 4-aminopyridine (a potassium channel blocker) to the heat-damaged sections of the nerves studied in vitro restored the amplitude of the compound action potential to con- trol levels when treatment started within 10min of injury. The restoration of nom-tal nerve function occurred more rapidly and persisted for at least 60 min when the injury was inflicted in vivo.

Eliasson S. G. and Monafo W. W. (1989) 4aminopyridine restores conduction in heat-blocked sciatic branches. J. Bum Care &habil. 10,(6), 499-503.

LABORATORY STUDIES

Optimal conditions for in vitro growth of human keratinocytes The conditions for encouraging the maximal rate of proliferation of human keratinocytes in culture have been determined. An opti- mal rate of development followed from a primary plating density of 2 x 10' cells/an’, transfer to secondary culture B-10 days later or before confluence slowed cell growth and a growth medium containing between 1.25 and 5 per cent fetal bovine serum or 5 per cent human albumin.

deSerris S., Herzog S. R., Meyer A. A. et al. (1989) Techniques to accelerate the availability of human keratinocyte grafts. J Bum Care Rehabil. 10, (6), 469-475.