Gregory L. Brown

Enhancement of wound healing by topical treatment with epidermal growth factor.

Experimental studies in animals have demonstrated that the topical application of epidermal growth factor accelerates the rate of epidermal regeneration of partial-thickness wounds and second-degree burns. We conducted a prospective, randomized, double-blind clinical trial using skin-graft-donor sites to determine whether epidermal growth factor would accelerate the rate of epidermal regeneration in humans. Paired donor sites were created in 12 patients who required skin grafting for either burns or reconstructive surgery. One donor site from each patient was treated topically with silver sulfadiazine cream, and one was treated with silver sulfadiazine cream containing epidermal growth factor (10 micrograms per milliliter). The donor sites were photographed daily, and healing was measured with the use of planimetric analysis. The donor sites treated with silver sulfadiazine containing epidermal growth factor had an accelerated rate of epidermal regeneration in all 12 patients as compared with that in the paired donor sites treated with silver sulfadiazine alone. Treatment with epidermal growth factor significantly decreased the average length of time to 25 percent and 50 percent healing by approximately one day and that to 75 percent and 100 percent healing by approximately 1.5 days (P less than 0.02). Histologic evaluation of punch-biopsy specimens taken from the centers of donor sites three days after the onset of healing supported these results. We conclude that epidermal growth factor accelerates the rate of healing of partial-thickness skin wounds. Further studies are required to determine the clinical importance of this finding.

Traumatic diaphragmatic hernia: a continuing challenge.

Traumatic diaphragmatic hernia is an uncommon but important problem in the patient with multiple injuries. Since diaphragmatic injuries are difficult to diagnose, those that are missed may present with latent symptoms of bowel obstruction and strangulation. From 1957 to 1982, we treated 41 patients with traumatic diaphragmatic hernias. In 39 patients (95%), diaphragmatic hernia followed blunt trauma. The herniation occurred on the right side in 14 patients and on the left side in 29; it was bilateral in 2. Twenty-four patients had diagnostic chest radiographs, and an additional 11 had abnormal but nondiagnostic studies. Peritoneal lavage was of little value in making the preoperative diagnosis. Twenty-three patients underwent laparotomy only, 13 required thoracotomy alone, and 5 had combined laparotomy and thoracotomy. There were 7 deaths (17%) from associated injuries. Only one missed injury was encountered; a second delayed hernia, initially treated elsewhere, was repaired 45 years after the original trauma. Traumatic diaphragmatic hernia should be suspected on the basis of an abnormal chest radiograph in the trauma victim with multiple injuries. Right-sided injuries occur more commonly than previously thought and often require dual incisions (laparotomy and thoracotomy) for diagnosis and treatment. The organization of emergency care for such patients is critical in avoiding the potential of long-term sequelae.

Effect of topical recombinant TGF-β on healing of partial thickness injuries

Peptide growth factors produced by platelets, macrophages, epidermal, and dermal cells may play key roles in regulating healing of partial-thickness skin wounds. We examined the effects of recombinant transforming growth factor beta (TGF-beta) on cultures of epidermal and dermal cells in vitro and on healing of partial-thickness injuries in vivo. Increasing concentrations of TGF-beta (0.1, 1, and 10 ng/ml) progressively inhibited serum-stimulated DNA synthesis by up to 95% in cultures of adult human keratinocytes during 48 hr of exposure to TGF-beta. In contrast, TGF-beta (10 and 100 ng/ml) in serum-free media stimulated DNA synthesis by up to 80% compared to serum-free control cultures of adult human dermal fibroblasts. To evaluate the effects of TGF-beta on healing of partial-thickness injuries in vivo, wounds (20 x 20 x 0.6 mm) were created on the dorsal thoracolumbar region of adult pigs by an electrokeratome and were treated daily for 5 days after injury with vehicle or vehicle containing 0.1 or 1 microgram/ml TGF-beta and covered with occlusive dressing. Computerized planimetry of wound photographs demonstrated that TGF-beta treatment stimulated statistically significantly increases in the area of regenerated epidermis compared to wounds treated with saline vehicle on Days 3, 4, 5, and 7 after injury probably due to TGF-beta increasing the rate of epidermal cell migration. In addition, morphometry of biopsy specimens showed that TGF-beta treatment stimulated statistically significant increases in the cross-sectional depths of regenerated dermis compared to wounds treated with saline or Silvadene vehicles on Days 5, 6, and 8 after injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of muramyl dipeptide and clindamycin in a murine abdominal abscess model

Peritonitis and subsequent local and remote complications are an important source of morbidity and mortality, which persist despite the best available treatment. Reasonable therapeutic efforts, therefore, have included stimulation of host defenses with immune adjuvants, recently typified by muramyl dipeptide (MDP). Murine abdominal abscesses were created by intraperitoneal injection of Bacteroides fragilis and autoclaved fecal suspensions, and the effects of MDP and clindamycin on these abscesses were evaluated. At 10(4) colony-forming units (CFU) per milliliter of Bacteroides fragilis, intraperitoneal clindamycin was effective in reducing both the incidence of abscess formation as well as the number of abscesses per mouse as compared with controls at doses of 5 mg/kg and 2 mg/kg (P less than 0.01). The effect was more significant when the drug was given 30 min prior than when given after injection of organisms (P less than 0.02). At 10(7) and 10(8) CFU/ml, pretreatment with MDP increased abscess formation (P less than 0.05, P less than 0.01), an effect that was obscured by clindamycin administration, which decreased number of abscesses from controls irrespective of pretreatment with MDP. Abscesses were present on the third day after injection, and MDP, paradoxically, had increased the number of abscesses by the fifth day. Clindamycin reduced abscess formation at all concentrations of bacteria and had a dose and time-dependent response. MDP increased abscess formation only at high concentrations of Bacteroides fragilis, but clindamycin abolished this effect and reduced the number of abscesses to similar levels in both the clindamycin alone and clindamycin + MDP groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Muramyl dipeptide protects decomplemented mice from surgically-induced infection

Muramyl dipeptide (MDP) is a natural product of bacterial cell-wall breakdown, which can now be produced synthetically; it is the smallest component of the mycobacterial cell wall capable of reproducing the adjuvant activities of Freunds complete adjuvant. We tested the well-documented, protective effect of MDP to increase survival in a murine model simulating surgically-induced bacteremia. The protocol involved the bacterial innoculation of control and decomplemented mice in the presence and the absence of pretreatment with MDP. Bacteremia in both the control and decomplemented groups pretreated with MDP was decreased statistically at 24 h (P less than 0.01) as compared to controls. Likewise, survival was increased significantly at 24 h (P less than 0.05), 48 h (P less than 0.001), and 72 h (P less than 0.001) using the same group comparisons. We conclude, therefore, that MDP maintains its protective effect in the absence of complement, supporting the view that the mechanism of action of MDP is complement independent.

Muramyl dipeptide and polymorphonuclear leukocyte chemotaxis in vitro

Muramyl dipeptide (MDP) is an immunostimulatory agent that has been shown repeatedly to provide protection against the effects of some forms of experimental surgical infection. The mechanisms of this protection are incompletely understood, and in order to further define them, the impact of MDP upon in vitro polymorphonuclear (PMN) leukocyte chemotaxis was examined in the presence of both normal and opsonic depleted serum. We have also evaluated the effect of MDP as a chemoattractant itself and the response of neutrophils along with MDP to a standard chemoattractant, n-formyl-L-methionyl-L-leucyl-L-phenyl-alanine (FMLP), using the agarose assay for chemotaxis. MDP has weak but significant chemotactic activity itself, with a peak effect at a concentration of 5 X 10(-8) micrograms/ml for neutrophils. These effects are enhanced by the addition of 10% serum. MDP more strongly enhances neutrophil chemotaxis to FMLP. The enhancement of chemotaxis may be a factor in the protection that MDP exerts against some experimental bacterial challenges.

Characterization of neutrophil iodination for the assessment of phagocytic and opsonic function in septic patients

To increase our understanding of the nature of surgical infection, further studies on the host defense abilities of infected patients are required. Therefore, a more thorough investigation of the iodination method for the measurement of polymorphonuclear leukocyte function and serum opsonic activity was undertaken to characterize its application in surgical infection. A significant relationship was found between the phagocytic indices derived from different standard neutrophils or sera measured on the same day. When expressed as a value of normal phagocytic indices minus abnormal phagocytic indices, this relationship was constant from day to day despite wide variations in the absolute phagocytic index values. This finding enables direct comparisons to be made between the values obtained both from the same patient and from different patients during the course of their illness by reference to daily control values. We also found that the system was sufficiently sensitive to detect, in a dose-responsive manner, the changes induced in normal neutrophil phagocytosis and serum opsonic activity by a specific bacterial challenge with either K. pneumoniae or E. coli. In addition, zymosan, which is utilized in the iodination reaction but also has immunoadjuvant properties, was found to enhance neutrophil function but depress serum opsonic activity in the face of such bacterial challenges. We conclude that the iodination technique is a credible method for the indirect measurement of polymorphonuclear phagocytosis and serum opsonic function in the face of a bacterial challenge and can be reliably employed in studies of septic patients provided these findings are taken into account.