George W. Cherry

Histomorphologic evaluation of guinea pig skin and soft tissue after controlled tissue expansion.

To evaluate the histologic changes attendant on tissue expansion in the guinea pig, self-inflating implants were placed in the dorsal subcutaneous space and the tissue response was sequentially studied at periods ranging from 1 to 18 weeks. Fixation artifacts have been minimized. The cellular response is relatively benign. The epidermis does not undergo thinning during expansion, although dermis and panniculus carnosus become significantly thinner. Atrophy of panniculus muscle is demonstrable. This study supports the hypothesis that tissue expansion results in a net gain of donor tissue.

Evidence of oxidative stress in chronic venous ulcers

Reactive oxygen species have been implicated in the impaired healing of chronic leg ulcers but little direct evidence is available. We have observed a significant (p < 0.01) elevation of the allantoin : uric acid percentage ratio, a marker of oxidative stress, in wound fluid from chronic leg ulcers (median 17, range 8–860) compared to both paired plasma (median 2, range 1–8) and acute surgical wound fluid (median 4, range 3–7). However, the allantoin : uric acid percentage ratio did not differ significantly between chronic wounds that healed and those that failed to heal. Neutrophil elastase was elevated 30‐ to 1300‐fold in chronic wound fluid compared to plasma and there was a correlation (r 2 = 0.742) between wound fluid elastase and the allantoin : uric acid percentage ratio. Total antioxidant capacity of wound fluid, as measured with a chemiluminescence assay, did not show a correlation (r 2 = 0.03) with the observed oxidative stress. These observations suggest that conditions of localized oxidative stress, possibly related to neutrophil‐associated production of reactive oxygen species, are present in chronic leg ulcers. It is possible that future therapeutic strategies aimed at reducing oxidative stress, in addition to good standard care, could improve healing rates of chronic wounds. (WOUND REP REG 2003;11:172–176)

Validation of venous leg ulcer guidelines in the United States and United Kingdom

BACKGROUND Venous leg ulcers account for 85% of all lower-extremity ulcers, with treatment costs of 3 billion dollars and loss of 2 million workdays per year. The purpose of this study was to validate the clinical efficacy and cost effectiveness of multidisciplinary guidelines for the diagnosis and treatment of venous leg ulcers. METHODS Eighty (40 retrospective, 40 prospective) patients from the United States and United Kingdom were enrolled. RESULTS United States patients were 6.5 times and United Kingdom 2 times more likely to heal if a guideline was followed (P <0.001). A significant decrease was noted in healing time for both the United States and United Kingdom (P <0.01), and the median cost decreased significantly when the guideline was followed (P <0.01). CONCLUSIONS Implementation of a guideline for diagnosis and treatment of venous leg ulcers resulted in improvement in diagnosis, decrease in healing time, and an increase in healing rates resulting in lower costs.

Electron Microscopic Evaluation of Guinea Pig Skin and Soft Tissues “Expanded” with a Self-Inflating Silicone Implant

An electron microscopic study of guinea pig skin and soft tissue after expansion by self-inflating silicone implant for periods of 7 weeks to 8 months revealed definite ultrastructural changes. In the epidermis, the cells of the malpighian layer contained larger groups of tonofilaments forming tonofibrils. Intercellular spaces in all layers of expanded epidermis were much more reduced than in normal epidermis. The basal lamina and the laminar surfaces of the basal cells demonstrated more undulation than those of the controls. The expanded dermis contained large bundles of compacted collagen fibers, as well as thin collagen fibers, active fibroblasts, and a few myofibroblasts. The subcutaneous tissue contained a paucity of adipose tissue and thickened collagen fibers in the interlobular spaces. The skeletal muscle showed larger amounts of sarcoplasm in relation to myofibrils. An increased number and size of mitochondria were found with sarcomeres abnormally arranged. The capsule around the implant was composed of active, elongated, and flattened fibroblasts and bundles of collagen fibers with variable fiber width. Intracellular collagen fibers were found in the cytoplasm of the fibroblasts. Myofibroblasts in the capsule were observed more often in early expanded tissue. Small blood vessels in the capsule showed multiplication of the basal lamina or were surrounded by a very wide, homogenous material. Inflammatory cells were not found in the capsule. Such findings are important in developing and evaluating future skin-expansion research in humans and animals.

Effects of Buddleja globosa leaf and its constituents relevant to wound healing

An aqueous extract of Buddleja globosa leaves, used traditionally in Chile for wound healing, was tested for the ability to stimulate growth of fibroblasts in vitro and for antioxidant activity in the same fibroblast cell system challenged with hydrogen peroxide. Low concentrations of the extract gave an increase in fibroblast growth which was not statistically significant but cytotoxicity was observed at concentrations greater than 50 microg/ml. The extract showed strong antioxidant effect and fractionation led to the isolation of three flavonoids and two caffeic acid derivatives, each of which was shown to contribute to the antioxidant effect at concentrations below 10 microg/ml. These activities would accelerate the healing of wounds.

Simple biochemical markers to assess chronic wounds.

We investigated the potential for the biochemical analysis of chronic wound fluid to predict healing using simple and widely available analytes in an out‐patient clinic setting. Wound fluid was collected from 12 patients attending a leg ulcer clinic and analyzed for a variety of analytes, including lactate, total protein, and albumin. Twelve weeks after collection the wound was assessed for healing (defined as complete healing or greater than 50% reduction in wound size). The median total protein (44.3 ± 8.8 g/l) and albumin (25.0 ± 2.3 g/l) concentrations in exudate collected from four healing wounds were significantly higher (p < 0.05) than in exudate from eight nonhealing wounds (median total protein 29.7 ± 7.6 g/l, median albumin 17.0 ± 4.3 g/l). No significant difference was observed for lactate. A second specimen of wound fluid was collected from four of the patients (three nonhealing and one healing). The protein analysis confirmed the pattern observed for the first collection: nonhealing wounds had total protein and albumin which remained low compared to healing wounds. No wound with an exudate albumin of less than 20 g/l healed. Both total protein and albumin are stable analytes which can be easily measured in any laboratory and may offer a simple biomarker of healing in chronic wounds.

Regional Differences in Capillary Density of the Normal Human Dermis

Quantitative study of the capillary density of normal dermis of 113 biopsy specimens taken from 20 body sites from 6 cadavers was carried out. Histologic quantification of dermal capillaries using the alkaline phosphatase method to delineate vascular endothelium and automated image analysis demonstrates statistically significantly greater capillary density in the head-face/neck region both in the papillary and reticular dermis than in the lower parts of the body. The smallest numbers of the dermal capillary density were noted in the calf and shin areas. These data support the hypothesis that random-pattern skin flaps can be safely raised longer in the face and neck than in other parts of the body.

Perfusion imaging of skin island flap blood flow by a scanning laser-Doppler technique

Conventional laser-Doppler perfusion measurements can only obtain information from a single site. Since superficial blood flow is heterogeneous, this is a serious limitation, particularly in studies of methods to improve skin flap survival. A scanning laser-Doppler instrument has been developed which provides both an image and quantitative information about perfusion of the superficial tissue. We have evaluated this instrument in a circumflex iliac artery island flap model in the pig. The validity of the model was demonstrated by fluorescein dye injection and histology. Elevation of flaps was found to increase proximal flap blood flow but to decrease it in the distal portion. In flaps subjected to arterial ischaemia (9 h) and reperfusion we found an early increase in proximal flow, which gradually extended distally over the first 40 to 60 min. 16 h later, flow had declined, compatible with reperfusion damage to the vasculature. We suggest that perfusion imaging may be a valuable technique for investigating the mechanisms and extent of reperfusion injury.

Relationship between edema and the healing rate of stasis ulcers of the leg

Abstract Leg volumes and ulcer size were measured in patients who underwent four consecutive different treatment regimens for stasis ulcers. Most ulcers enlarged on simple wound care. Any regimen which included external support led to healing, but there was no correlation between the healing rate and the amount of swelling in the leg. Our evidence suggests that both the ulcer and the edema are due to the same cause, probably venous stasis, and any therapy which does not improve venous drainage is probably doomed to failure.

LASER DOPPLER IMAGING OF SKIN MICROCIRCULATION

Laser Doppler imaging (LDI), a new technique which allows measurement of skin blood perfusion at a distance from the skin surface, was assessed methodologically in healthy volunteers. Each skin LDI value was based on virtually real-time measurements obtained from a number of discrete measuring sites. In scans made along the circumference of the lower arm, valid figures for LDI (as distinct from no output at all) were obtained in 8/8 measurements at 0 degrees inclination, and in 16/16 measurements at 7 degrees, 14 degrees, 22 degrees, 30 degrees and 38 degrees, respectively. Beyond this inclination a numerical output was obtained in only 9/16 of measurements at an inclination of 48 degrees, in 7/16 at 69 degrees, and in no more than 1/16 at 90 degrees. Values obtained at angles of inclination greater than 38 degrees fell within the relatively narrow range of values obtained at lesser angles of inclination. The findings are of interest since measuring sites of clinical importance may not be flat. Variability of measurement (coefficient of variation in per cent) was studied in the lower leg by performing LDI and conventional laser Doppler flowmetry (LDF) concomitantly. The coefficient of variation for measurements in one subject at rest was 13% for LDI vs. 19% for LDF, the corresponding interindividual coefficient of variation values being 25% vs. 28%. In response to heating, finger pulp perfusion increased by 55% as measured by LDI (p = 0.0051) and by 44% (p = 0.0756) as measured by LDF. In summary, the findings contribute to the validation of LDI for skin perfusion measurement.