Purification and identification of a human dermal extract component inhibitory to fibroblast proliferation.

It was previously shown that a citric acid buffer extract of human dermis (extract D) inhibited growth of human diploid fibroblasts in monolayer culture (Muir et al., 1997). Further fractionation has shown that the active principle is probably a proteoglycan, and that retention of its inhibitory activity is dependent on the use protease inhibitors throughout the extraction procedure. Elution of extract D from a DEAE-cellulose column produced four major peaks, each of which was subjected to SDS-PAGE as well as being tested for inhibitory activity on the growth of fibroblasts in culture. Peaks III and IV had no inhibitory effect, but peak I contained highly active material. Gels of this peak showed prominent bands of 120 kDa (corresponding to dermatan sulphate proteoglycan II, DS-PG II) and at 45 kDa (corresponding to the core protein). The latter band became more prominent when extract D which had been treated with chrondroitinase ABC was electrophoresed. Their identities were verified by Western blotting. Peak II also contained some slower-acting inhibitory material which has as yet to be identified, but contains little or no protein corresponding to the decorin core-protein. The data indicate that the intact decorin molecule, DS-PG II, is the main inhibitory principle in human skin.

Inhibition of the contraction of collagen gels by extracts from human dermis.

Extracts from the human dermis were prepared and evaluated with respect to their ability to influence fibroblasts to contract collagen gels in vitro. The extract which had the most inhibitory effect on fibroblasts to cause contraction of collagen gels was extract D. It also inhibited fibroblast growth. Inhibition of contraction was not simply related to fibroblast cell numbers and the data suggests a specific effect upon the ability of fibroblasts to cause contraction. Other extracts were without significant effect.

Growth inhibition of cultured fibroblasts by extracts from human dermis.

In incised wounds and deep partial thickness burns the resident fibroblasts in the dermis remain inactive. The fibroblasts responsible for repair at the dermal level come from the subdermal layer. The hypothesis is that the inactivity of the dermal fibroblasts is due to an inhibitory substance in the dermis. To test this hypothesis extracts were made of normal dermis and of mature scar tissue and these extracts were applied to fibroblasts growing in monolayer culture. Both extracts and cells were obtained from human tissue. It was shown that extracts, particularly the extract made with citric acid/citrate buffer, pH 3.5, caused inhibition of fibroblast growth. Present evidence suggests that the active principle may be a proteoglycan.

Effects of plane mechanical forces in wound healing in humans.

The effects of the application of external forces acting in the plane of the skin on early scars during healing were investigated. A simple apparatus was developed for this purpose. The scars were followed up for a minimum of 12 months postoperatively and all settled well.

Aggressive pilomatricoma in childhood.

Pilomatricoma (calcifying epithelioma) is a benign tumor of the hair matrix cells that presents most frequently in childhood. Most are benign and slow growing and do not recur after excision. A small number of aggressive or malignant variants have been reported that recur if not widely excised. We report on an aggressive variant occurring in a 4-year-old boy and advise caution in treating cutaneous "cysts."

The role of lymphocytes in wound healing.

In the past, lymphocytes have usually been associated with chronic inflammatory conditions and only recently have animal experiments indicated a possible role in wound healing. The present paper describes a study of lymphocytes in human wounds and scars using monoclonal antibody stains. The results suggest that T lymphocytes may play an important regulatory role in wound healing and scar formation.

On the nature of keloid and hypertrophic scars.

Clinical observations make it possible in most cases to differentiate between keloid and hypertrophic scars. This suggests that different biological factors are involved in the two groups. In clinical practice in the United Kingdom most keloid scars occur spontaneously. In black-skinned people and orientals the factors of keloid and hypertrophic scars may overlap and potentiate each other.

The treatment of deep dermal burns by abrasion.

Deep dermal burns usually heal by a combination of epithelialisation and granulation tissue formation, and may form hypertrophic scars. Sometimes, however, they heal spontaneously and early with no hypertrophy. Early tangential excision and grafting is practised by many surgeons for these burn wounds, but, because of the problems of diagnosis and therefore the risks of unnecessary surgery, we have practised a policy of abrasion of burn wounds unhealed at two weeks after injury. The wounds were over-grafted or not depending on the appearance of the remaining dermis. Healing was generally rapid. Long term results show good scar formation with few problems from scar hypertrophy or contracture.

Maxillary development in cleft palate patients with special reference to the effects of operation.

Thirty-one patients whose complete unilateral clefts of lip and palate had been repaired by early operation were followed up for 18 years. The results showed that repair of the hard palate is followed by deformity of the maxilla in a sufficient number of patients to suggest that we need to look for improved methods of repair of the hard palate.

Primary flexor tendon repair: the mechanical limitations of the modified Kessler technique.

The aim of primary suture of flexor tendons in the hand is to achieve full function as soon as possible with a one stage operation. Much interest has been aroused by this subject and more recently by the possibility of improving results by postoperative active movement of the repaired tendon. We report the results of mechanical testing of the modified Kessler suture which suggests that the peripheral stitch is an important structural component of the suture. It is not merely a 'tucking in' stitch, but is essential to prevent very early gap formation. Steel is the best material for the central or core part of the suture. Cautious active postoperative movements may be possible using the modified Kessler suture, but within a narrow range of safety and with careful supervision.

Exposure treatment of the burned patient--a computer simulation of the thermal environment and its effect on evaporation and heat loss.

The influence of the thermal environment on evaporation and heat loss from burned tissue has been studied in order to optimise conditions for treatment of severely burned patients. Diffusion resistances have been defined to describe movement of water vapour through the skin and away from the body surface. These have been evaluated from experiments on a water phantom and from data on evaporation rates from burned tissue and normal skin. Results show that the diffusion resistance for burned tissue is less than one tenth of that for normal skin, but changes substantially during the development of an eschar. Evaporation is promoted by a high skin temperature and a low relative humidity, but not by raising the ambient air temperature. Blowing warm dry air over a burn wound will enhance evaporation and reduce heat loss, encouraging the rapid formation of a dry eschar to provide a barrier against infection. Selective irradiation of burned tissue with low levels of radiant energy can be used to compensate for local heat losses, and allow the air temperature in the treatment room to be kept at a level comfortable for the patient and nursing staff.

A hypothesis of the healing of deep dermal burns and the significance for treatment.

Deep dermal burns heal by a combination of new connective tissue formation (granulation) and epithelialization. In deep dermal wounds, which are unhealed after 14 days of conservative treatment, epithelialization can be enhanced by abrasion either alone or combined with provision of a skin graft. Some 42 burn wounds in 25 patients treated by this method have healed quickly and with good results. This method represents a move away from the current trend of early tangential excision and grafting of burn wounds and raises the possibility of developing a regime with the advantages but not the disadvantages of early tangential excision and grafting.

The use of infrared radiation to reduce heat loss in burned patients: experiments with a phantom.

Heat losses from patients with severe burns place considerable demands on the body. The metabolic rate, already elevated as a result of the injury, must rise further to maintain thermal equilibrium. To compare different methods of supplying heat to burned patients, a phantom has been constructed in which a free water surface has been used to simulate burned tissue. The effect of environmental temperature, humidity and air velocity, and of radiant energy, on the evaporation rate from the water surface, and on the energy supplied to the water to maintain its temperature, have been measured. Results showed that humidity and air velocity were the main factors determining evaporation. The internal energy required to maintain the temperature of the phantoms could be reduced by use of infrared radiation. This is particularly appropriate in the clinical situation, as energy is supplied to the skin surface, where it can replace directly energy lost through evaporation. Because the effect of radiant energy on the evaporation rate was small, it may be possible to create a microclimate around a patient where air velocity can be set to give a desired rate of evaporation, and the infrared level can be adjusted for patient comfort.