Annals of Burns and Fire Disasters - vol. XIV - n° 2 -June 2001.

INTERNATIONAL ABSTRACTS

ROLE OF WOUND HEALING MYOFIBROBLASTS ON RE-EPITHELIALIZATION OF HUMAN SKIN

Large burned surfaces heal by using two concomitant phenomena: re-epithelialization and dermal neoformation. While the role of the interaction between keratinocytes and fibroblasts has been widely studied, less is known about the relationship between healing myofibroblasts and keralinocytes, even if the two cell types co-exist during the healing process. An in vitro skin model was used to investigate the influence of myoiibroblasts on keratinocyte growth and differentiation. A histological study determined the speed and quality of epithelialization. A continuous epidermis formed in 7-10 days when the dermis presented a population of fibroblasts, while with wound healing myofibroblasts complete reepithelialization did not occur during the 10-day period that was studied. After seven more days of epidermal differentiation, histological tests showed that the epidermis was more disorganized and that the expression of basement membrane constituents reduced when wound healing myofibroblasts or no cells were added to the dermis instead of fibroblasts. It would therefore appear, on the basis of these findings, that wound healing myofibroblasts are not capable of stimulating keratinocyte growth or differentiation. When fibroblasts were treated with TGF(3 there was an increase in epidermal cell differentiation, as seen when myofibroblasts were present. This cytokine did not however alter the re-epithelialization rate but induced an increase of basement membrane matrix deposition in opposition to myofibroblasts. The different keratinocyte reactions to fibroblasts and wound healing myofibroblasts cannot therefore be explained only by TGF(J action. It is thus concluded that only a limited role is played by myofibroblasts in the re-epithelialization process and also that myofibroblasts may be more closely associated with the increase in extracellular matrix secretion.

Moulin V., Auger F.A., Garrel D., Germain L. Burns, 26: 3-12, 2001

IMPORTANCE OF NITRIC OXIDE IN THE REGULATION OF 13URN OEDEMA, PROTEINURIA AND URINE OUTPUT

In view of the uncertainty about whether nitric oxide (NO) radicals play a protective or a harmful role after a burn trauma, a study was performed in order to study the role of NO in burn-induced inflammation and its importance in regulating burn pathophysiology. The effects were investigated of the NO precursor L-arginine and of the NO-synthase inhibitor NG-nitro-L-arginine (L-NNA) on plasma extravasation in fullthickqess bums, as measured by spectrophotometric analysis of Evans blue albur rin. The effects on diuresis and proteinuria were also investigated. The results of the investigation are presented. It was found that the accumulated urine volume 90 min post-burn increased tenfold in burned animals treated with L-arginine compared with saline-treated controls (p < 0.001) and non-burned animals (p < 0.001) and that L-NNA did not have a significant effect on diuresis. Significantly more proteinuria occurred in L-arginine treated animals than in burned and non-burned controls (p < 0.001), while L-NNA had no significant effect on the leakage of protein into the urine. The activation of NO synthesis significantly reduced bum oedema and greatly increased diuresis together with proteinuria.

Lindblom L., Cassuto J., Yregdrd L., Mattson U., Tarnow P., Sinclair R. Burns, 26: 13-17, 2000

HAEMODYNAMIC AND OXYGEN TRANSPORT RESPONSES IN SURVIVORS AND NON-SURVIVORS FOLLOWING THERMAL INJURY

The aim of this study was to observe the haemodynamic and oxygen transport variables in a group of patients with major thermal injury in an attempt to detect possible differences in the response of survivors and non-survivors to the injury. Twenty-one patients admitted consecutively to an intensive burn care unit over a 16-month period were considered. The transpulmonary thermodilution technique was used for the monitoring. Six of the patients eventually died. Survivors were found to have a significantly higher cardiac index and oxygen delivery rate during the early post-burn period than non-survivors. Initial serum lactate levels were found to be significantly associated with survivals, as also the ability to clear elevated lactate. It was concluded that standard vital signs such as blood pressure and heart rate (which were not significantly different between the two groups of patients) may not be valid as outcome-related resuscitation goals, and not sufficiently sensitive to guarantee accurate fluid replacement. The response to fluid therapy may be significantly related to outcome, with survivors responding with an increase in cardiac output and oxygen delivery that is not seen in nonsurvivors. It seems that lactate levels correlate with organ failure and death, and appear to be a suitable end-point for the resuscitation of severely burned patients.

Holm C., Belcer B., Forbrand F., Worl H.H., Henckel von Donnersmarck G., Muhlbauer F. Burns, 26: 25-33, 2000

COMPARISON OF SERUM AND PLASMA LACTATE DEHYDROGENASE IN POST-BURN PATIENTS

An investigation was made into the difference in lactate dehydrogenase (LDH) activity between serum and plasma in post-bum patients. Seventy-four bum patients were considered with regard to LDH activity in the serum and plasma, using a CX-7 automatic biochemistry bioanalyser. It was found that LDH activity in plasma was significantly higher than in serum (p < 0.001) The higher LDH activity may have been caused by leakage of LDH from ruptured platelets during the process of LDH assessment. It is important to distinguish between serum and plasma LDH when considering test results as an aid to diagnosis.

Liu Z., Wang W., He C.Burns, 26: 46-8, 2000

EPIDEMIOLOGICAL STUDY OF 3341 BURN PATIENTS DURING THREE YEARS IN TEHRAN, IRAN

This study was conducted in order to identify risk and predisposing factors in 3341 burn patients treated in a burns centre in Iran in the period 1995-98. The aim was also to compare the experience acquired with that reported by other researchers and to arrive at an appropriate bum prevention programme. The mean age of the patients was 24.4 yr and the mean total body surface area burned was 30.6%, and 43.5% of the patients were aged under 15 yr. Flame was the commonest cause of burns. The mean hospital stay was 16.7 days, and the overall mortality rate was 19.6%. It is concluded that the home was the place where people were most at risk of burn injuries, that parents played the most important role in the prevention of burns in children (who formed the largest single group of patients), and that the causes of burns that were identified should be widely publicized through the news medium

Lad A.R., Alaghehbandan R., Nikui R.Burns, 26: 49-53, 2001

A NEW SYSTEM FOR THE CULTIVATION OF KERATINOCYTES ON A CELLULAR HUMAN DERMIS WITH USE OF FIBRIN GLUE AND 3T3 FEEDER CELLS

A comparison was made of the growth of human keratinocytes on human acellular dermis in four different cultures. The epidermis was completely separated and removed from the dermis after the skin samples had been soaked for one week in 0.1% trypsin at 4 °C. Forty pieces of saline-washed dermis, each measuring 1 cm 2, were randomized in 4 groups: in group A human keratinocytes that had undergone two to three cell passages were seeded onto the dermis and sprayed with a thin layer of fibrin glue and proliferative 3T3 feeder cells growing separately on the culture dish; in group B the dermis was sprayed only with fibrin glue; in group C the dermis was treated with 3T3 cells only; and in group D the dermis was not sprayed at all. The histological results of the composite grafts at two weeks were assessed as having either scanty colonies of keratinocytes, continuous stratified epithelium, or no observable keratinocyte growth. Good results were found in group A (eight out of ten demonstrated continuous stratified epithelium), which indicated that the fibrin glue facilitated the seeding efficiency of the keratinocytes on the dermis and that the vital factors released from the 3T3 feeder cells enhanced the growth and differentiation of the keratinocytes. This model represents an optimal system for the cultivation of keratinocytes on a cellular dermis.

Lam P.K., Shan E.S., Yen S.C., Lau C.H., King W.W.K.J. Burn Care Rehabil., 21: I-4, 2000

EFFICACY OF GROWTH FACTORS IN THE ACCELERATED CLOSURE OF INTERSTICES IN EXPLANTED MESHED HUMAN SKIN GRAFTS

The purpose of this study was to assess the efficacy of various cytokines and growth factors in the closure of human meshed skin graft interstices by epithelialization. The determinations were made using the athymic nude rat model. An investigation was made of the epithelialization kinetics of interleukin-4 (1L-4), macrophage colony-stimulating factor, keratinocyte growth factor-1 (KGF-1), keratinocyte growth factor-2 (KGF2), basic fibroblast growth factor (bFGF), and transforming growth factor beta-2 (TGFB2). The results obtained were compared with the epithelialization rates of grafts treated with a vehicle control. On postoperative day 3, the wounds treated with IL-4, KGF-2, bFGF, and TGFB2 showed a significantly increased rate of interstitial closure (p < 0.05). On post-operative days 5 and 7, the wounds treated with KGF-2, bFGF, and TFGB2 all showed a significantly higher rate of interstitial closure (p < 0.05). It would therefore appear that epithelialization kinetics can be accelerated by the use of several topical growth factors.

Smith P.D., Polo M., Soler P.M., McClintock J.S., Maggi S.P., Kim Y.J., Ko F., Robson M.C. J. Bum Care Rehabil., 21: 5-9, 2000

SITE-SPECIFIC IMMUNOSUPPRESSION: MECHANISMS OF CELLULAR IMMUNOSUPPRESSION THAT ARE OPERATIVE AT LOCAL AND SYSTEMIC LEVELS

A study was made of the cellular mechanisms that allow topical cyclosporine A (tCsA) to induce site-specific immunosuppression. The experiments designed succeeded in elucidating how cyclosporine A (CsA) suppressed activated immunocytes in animals subjected to local alloactivation and concomitant tCsA immune suppression. Lewis rats were given dual Lewis x Brown Norway rat skin allografts; the animals were treated with systemic CsA (sCsA) at a rate of 8 mg/kg per day for 10 days after grafting, followed by tCsA and then vehicle. CsA added to mixed lymphocyte reactions 24 h after culture initiation modelled the local prolonged local skin allograft survival. CsA inhibited both antigen-specific and nonspecific activated alloresponses of immunocytes from rats receiving allografts that underwent limited sCsA treatment only in a dose-dependent manner. In cases where tCsA had been applied, the immunocyte responses to a nonspecific antigen were highly CsA-resistant as compared with responses induced by antigen-resistant suppression. This nonspecific alloresponse was however fully suppressible with the use of high CsA doses (66 pg/ml). It can thus be concluded that alloresponding immunocytes were significantly more sensitive to CsA if they were challenged with the donor antigen and pre-exposed to limited sCsA followed by tCsA in vivo.

Patam M.A., Tran H.S., Llull R., Chrzanowski F.A., Black K.S., Hewitt C.W. J. Burn Care Rehabil., 21: 10-19, 2000

IN VIVO VISUALIZATION OF CEREBRAL MICROCIRCULATION IN SYSTEMIC THERMAL INJURY

A model is presented in order to describe the effects of systemic thermal injury in cerebral permeability with the use of an open, acute pial window technique. Sprague-Dawley rats were anaesthetized and an open pial window was constructed. The area was bathed with artificial cerebrospinal fluid with a pH adjusted to 7.4. Details of the process are provided. The model presented is the first to demonstrate changes in cerebral permeability after acute severe systemic thermal injury.

Barone C.M., Jimenez D.F., Huxley V.H., Yang X.J. Bum Care Rehabil., 21: 20-5, 2000

CONCEPTOS ACTUALES SOBRE LA PROBLEMATICA DE LA QUEMADURA DERMICA O INTERMEDIA O AB DE BENAIM (CURRENT CONCEPTS OF PROBLEMS RELATED TO DEEP DERMAL, OR INTERMEDIATE, OR BENAIM'S AB BURNS)

This article, in Spanish, describes the general problems presented by the dermal bum, and an analysis is made of the histology and functions of the various cell components of the epidermis and dermis, and of how they interact with the proteins in the extracellular matrix, collagen, and fibronectin; the action of growth factors in dermal burns is also considered. An analysis is also made of the physiopathology of this type of burn and of the healing processes and local and systemic factors involved. A presentation is made of the ideal treatment available today and of variant treatments.

Bolgiani A.N.B.Revista Argentina de Quemaduras, 14: 25-32, 1999