Duane L. Larson

The Hypertrophic Scar. Hexosamine Containing Components of Burn Scars

Summary A study has been made of the glucosamine, galactosamine, hyaluronic acid and chondroitin sulfate composition of hypertrophic scars, nonhypertrophic scars and normal skin. The galactosamine was consistently and significantly elevated in hypertrophic scars, indicating that the chondroitin sulfates were increased. Dermatan sulfate was found to be elevated in both hypertrophic and nonhypertrophic scars. Chondroitin-4-sulfate was found in the hypertrophic scar in significant amounts; only traces of this mucopolysaccharide were found in nonhypertrophic scar and in normal skin.

Management of Burns

An overview of the management of the acutely burned patient has been described. Adherence to the sound principles of early resuscitation, appropriate nutrition, wound management, and rehabilitation can provide hope for many of the victims of this tragic injury. Complications encountered throughout the burn illness present unique and perplexing problems for the physician, who must utilize all the clinical wisdom and facility available in the management of such complex problems.

The hypertrophic scar. Glycoprotein and collagen components of burn scars.

Summary A study of the hexose hexosamine, sialic acid, uronic acid, glycogen, and collagen fractions has been made on hypertrophic scars, nonhypertrophic scars, and normal skin. Hexose, hexosamine, sialic acid, uronic acid, and glycogen levels were significantly and consistently elevated in hypertrophic scars. These same components were slightly, but significantly, higher in the nonhypertrophic scars. Salt-soluble collagen of hypertrophic scars was significantly elevated, citrate-soluble and insoluble collagen fractions were not different in the three groups. From these data it is concluded that hypertrophic scars contain more glycoprotein and mucopolysaccharide and are more active metabolically.

Reconstruction of eyelids and eyebrows in burned patients.

The records of 283 consecutive patients treated for facial burns were reviewed. Eighteen percent of these patients had significant deformities of the eyelids or adnexal structures and underwent surgical correction. Our experience in managing these patients is presented and discussed.

Comparison of fresh, frozen and lyophilized porcine skin as xenografts on burned patients

Summary This study evaluated the differences between commercial porcine skin (fresh-frozen or frozen-irradiated and lyophilized) and the fresh porcine skin that is currently in use at our Burn Hospital. The different preparations of skin were evaluated by various clinical criteria including weight gain of the patient, relief of pain, joint movement, ease of application, development of sepsis and preparation of the granulation bed. We also did a cost accounting to compare the difference in price between commercial and fresh porcine skin. In addition, the development of anti-porcine antibodies after sequential xenograft applications were evaluated and the implications of this antibody response are discussed. From the data obtained it is felt that the commercial preparations of frozen porcine skin are a suitable alternative to fresh porcine skin for treatment of the burned patient.

Mechanisms of hypertrophic scar and contracture formation in burns

Abstract The hypertrophic scar with contracture formation begins when the integrity of the deep reticular portion of the dermis is interrupted. This wound following healing retains a bright red hue from increased vascularity. An increased number of fibroblasts and myofibroblasts move into the area and lay down collagen in an attempt to bridge the wound very much like a spider spins a web. And like a web the collagen, when allowed to come together, appears to form a tangled pattern, thereby shrinking the wound. The contracting myofibroblasts together with voluntary muscle contraction assist in this shrinkage. The fibroblasts are stimulated to produce chondroitin sulphate A, which may increase the firmness of the collagen entanglement. The hypertrophic scar and contracture formation can be markedly decreased with the use of constant pressure, splinting, and early skin grafting.

Prevention and management of contractures in patients with burns of the neck

Two hundred patients with neck burns were analyzed to determine the incidence of contractures. It was found that only 8 per cent of patients with second degree burns had contractures, all of which were mild. Both the overall incidence of cervical contractures in patients with third degree neck burns and their severity can be decreased by the use of a custom-formed isoprene splint. Splinting should begin as soon as possible after the burn and continue until scar maturation is complete.

Effect of thymosin on T-lymphocyte functions in patients with acute thermal burns.

Patients with severe thermal burns demonstrate a decreased cellular immunity. The purpose of this study was to ascertain whether thymosin enhances in vitro T-lymphocyte functions in such patients. Peripheral blood lymphocytes were obtained serially from 22 burned patients and 35 health adults. In vitro lymphocyte functions were evaluated by E-rosette formation, lymphocyte culture responses to PHA, Con A, PWM, PPD, SK-SD, mumps antigen, and tetanus toxoid, and mixed lymphocyte culture reactions. These tests were performed with and without in vitro addition of thymosin. Most of the parameters examined were significantly decreased in patients during the first 2 weeks postburn. The in vitro addition of thymosin significantly restored impaired lymphocyte responses, except in mixed lymphocyte culture reactions. These results demonstrate that thymosin enhances certain in vitro T-lymphocyte functions in burned patients. They further suggest that the administration of thymosin may restore decreased cell-mediated immunity in severely burned patients.

Permeability of blood vessels after thermal injury

Summary The permeability of the microcirculation in the canine mesentery, following heat stresses and topical application of histamine, was studied by introducing directly into the mesentric circulation albumin or dextran conjugated with fluorescein isothiocyanate, and then photographing while using an image intensifier (× 50 000). The experimental procedures were: ( a ) raising the temperature of an area of mesentery (0·33 × 0·21 inch) to 56 °C for 45 s; ( b ) infusing 10 ml of 0·9 per cent NaCl at a temperature of 55 °C into a mesenteric artery supplying the region being observed and then allowing the dogs own blood to perfuse this area; and ( c ) applying 2 ml of a 0·9 mg/ml solution of histamine in Ringers solution topically to the mesentery; the histamine was washed off the mesentery 2 min later. The infusion of fluorescein-tagged materials was performed at about 10 min after completing an experimental procedure and still or cine film was exposed at 5, 10 and 60 s after infusion of the tagged materials. The principal findings were that albumin and both the 70 000 and 150 000 MW dextrans passed from the circulating blood into the interstitial spaces primarily at bifurcations of venules when the tissue had not been exposed to heat or histamine. Following exposure to radiant heat, heated saline or histamine, venules and venous capillaries appeared to become more permeable to albumin and the two dextrans throughout their entire lengths. Venules and venous capillaries were less permeable to the 150 000 MW dextran than to albumin and the 70 000 MW dextran. No exit of tagged materials was observed from true capillaries. Based upon these and other observations in this laboratory, the cause of increased permeability appears to be a swelling of endothelial cells which we believe results from imbibition of water when the cells are subjected to heat injury or to an abnormal concentration of histamine. Since cell membranes are relatively non-distensible, a swollen endothelial cell becomes more spherical (less hexahedron-shaped) and consequently its contacting surfaces tend to pull away from adjacent surfaces of other endothelial cells. This causes spaces to open between the cells permitting leakage of relatively large molecules through walls of venules and venous capillaries.

Elastic tissue and hypertrophic scars

Abstract Because of the temporary lack of elastic fibres in scars, a histological investigation of the elastic fibres within the granulation tissue was carried out. The correlation between the type of scar developed and the presence of elastic tissue was studied in 342 granulation tissue biopsies of burned children. In the histological sections, elastic-like fibres, most of them fragmented with a degenerative appearance and a frequent giant-cell reaction, were seen at random, particularly in the patients that later developed hypertrophic scars. This response could contribute to the persistency of the chronic inflammatory process usually present in immature hypertrophic scars. On the other hand, the immunological response elicited by the injured elastic fibres could also be interfering with the normal pathway of the biosynthesis of the elastin, resulting in a failure of elastogenesis.