Search PubMed⌕ Search

Biomedical subjects

D G Greenhalgh

Publications and source records attributed to D G Greenhalgh.

At least 37 records · Page 2Linked to original sources
PubMed1995

Comparative assessment of cultured skin substitutes and native skin autograft for treatment of full-thickness burns.

OBJECTIVE: Comparison of cultured skin substitutes (CSSs) and split-thickness autograft (STAG) was performed to assess whether the requirement for autologous skin grafts may be reduced in the treatment of massive burns. SUMMARY BACKGROUND DATA: Cultured skin substitutes consisting of collagen-glycosaminoglycan substrates populated with autologous fibroblasts and keratinocytes have been demonstrated to close full-thickness skin wounds in athymic mice and to express normal skin antigens after closure of excised wounds in burn patients. METHODS: Data were collected from 17 patients between days 2 and 14 to determine incidence of exudate, incidence of regrafting, coloration, keratinization, and percentage of site covered by graft (n = 17). Outcome was evaluated on an ordinal scale (0 = worst; 10 = best) beginning at day 14, with primary analyses at 28 days (n = 10) and 1 year (n = 4) for erythema, pigmentation, epithelial blistering, surface roughness, skin suppleness, and raised scar. RESULTS: Sites treated with CSSs had increased incidence of exudate (p = 0.06) and decreased percentage of engraftment (p < 0.05) compared with STAG. Outcome parameters during the first year showed no differences in erythema, blistering, or suppleness. Pigmentation was greater, scar was less raised, but regrafting was more frequent in CSS sites than STAG. No differences in qualitative outcomes were found after 1 year, and antibodies to bovine collagen were not detected in patient sera. CONCLUSIONS: These results suggest that outcome of engrafted CSSs is not different from STAG and that increased incidence of regrafting is related to decreased percentage of initial engraftment. Increased rates of engraftment of CSSs may lead to improved outcome for closure of burn wounds, allow greater availability of materials for grafting, and reduce requirements for donor skin autograft.

Animals↗
PubMed1995

Maintenance of serum albumin levels in pediatric burn patients: a prospective, randomized trial.

A prospective, randomized trial was performed to determine whether maintaining serum albumin levels in burned pediatric patients had any effect on morbidity and mortality. Patients < 19 years of age with burns > 20% total body surface area were randomized to receive supplemental albumin to maintain levels 2.5 to 3.5 g/dL ("High Albumin") or were given albumin only if levels dropped < 1.5 g/dL ("Low Albumin") after completing burn shock resuscitation. The 36 patients in the Low Albumin group were well matched for age, burn size, depth of injury, and inhalation injury when compared with the High Albumin group (34 patients). As expected, serum albumin levels were significantly lower in the Low Albumin group when compared with the High Albumin group. No differences between groups were noted for resuscitation needs, maintenance fluid requirements, urine output, tube feedings received, days of antibiotic treatment, or ventilatory requirements. No differences in hematology, electrolytes, or nutritional laboratories were found. Finally, length of stay, complication rate, and mortality were not affected by albumin treatment. Albumin supplementation to maintain normal serum levels does not seem to be warranted in previously healthy children who suffer severe burns and who receive adequate nutrition.

Adolescent↗
PubMed1995

Topical nutrients promote engraftment and inhibit wound contraction of cultured skin substitutes in athymic mice.

Routine treatment of burns with cultured skin substitutes (CSS) has been limited by poor engraftment and by scarring. Hypothetically, topical application of essential nutrients and/or growth factors may support epithelial survival temporarily during graft vascularization. CSS, composed of human epidermal keratinocytes and dermal fibroblasts attached to collagen-glycosaminoglycan substrates, were incubated for 19 d in media optimized for keratinocytes. CSS, human xenografts, murine autografts, or no grafts were applied orthotopically to full-thickness skin wounds (2 x 2 cm) in athymic mice. Wounds were irrigated for 14 d with 1 ml/d modified cell culture medium or with saline containing epidermal growth factor, or were treated with dry dressings. After 6 weeks, treated sites were scored for percentage original wound area (mean +/- SEM) and percentage HLA-ABC-positive healed wounds [(number positive/n) x 100], and tested for significance (analysis of variance, p < 0.0001; Tukey test, p < 0.05). The data showed that CSS irrigated with nutrient medium were not statistically different in wound area (67.8 +/- 5.1%) from murine autografts (63.3 +/- 2.9%) but were statistically larger than human xenograft, no graft, or CSS treated with saline irrigation or dry dressings. HLA-ABC expression was 100% in CSS with nutrient irrigation, 86% in CSS with saline irrigation, 83% in CSS without irrigation, and 75% in xenografts with nutrient irrigation. These findings suggest that availability of essential nutrients supports keratinocyte viability during graft vascularization of CSS.

Administration, Oral↗
PubMed1994

PDGF and TGF-alpha act synergistically to improve wound healing in the genetically diabetic mouse.

Impaired wound healing results in significant morbidity for the surgical patient. The genetically diabetic (C57BL/KsJ-db/db) mouse is obese, hyperglycemic, insulin-resistant, and exhibits markedly impaired wound healing. Previous studies have demonstrated that the fibroblast mitogens, BB homodimer of platelet-derived growth factor (PDGF-BB) or basic fibroblast growth factor, plus insulin-like growth factor, act synergistically to enhance wound closure in the genetically diabetic mouse. The purpose of this study was to determine whether the keratinocyte mitogens, epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha), in combination with the fibroblast mitogen, PDGF-BB, would produce a similar synergistic enhancement in tissue repair. Full-thickness skin wounds created on the backs of diabetic mice received topical applications of vehicle (5% polyethylene glycol), PDGF-BB (10 micrograms), EGF (1 microgram), TGF-alpha (1 microgram), or the combination of PDGF (10 micrograms) and EGF (1 microgram) or TGF-alpha (1 microgram) for 5 consecutive days starting at wounding. Application of PDGF-BB or TGF-alpha alone to wounds in diabetic animals improved wound closure when compared to vehicle treatment. EGF did not affect healing and did not have any additive effects when combined with PDGF-BB. Significant improvements in wound closure were observed with the combination of PDGF-BB and TGF-alpha when compared to treatment with the individual growth factors. The PDGF-BB/TGF-alpha combination accelerated healing in the diabetic animals to a rate that was closer to that seen in nondiabetic mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The importance of intra-abdominal pressure measurements in burned children.

Four burned children suffering complications from elevated intra-abdominal pressures prompted initiation of a prospective study to determine the value of intra-abdominal pressure measurements in 30 children with large burns. Intra-abdominal pressures were measured every 4 hours during burn shock or sepsis, or daily during periods of stability. Patients were arbitrarily divided into those having one or more measurements > or = 30 mm Hg or all values < 30 mm Hg. Patients in the > or = 30 mm Hg group had significantly larger burns, higher mortality, and increased instances of sepsis. Five patients had elevated intra-abdominal pressures during burn shock, with two requiring abdominal escharotomies. Seven were at > 30 mm Hg during sepsis, with three requiring paralysis, and one each requiring placement of a peritoneal catheter or laparotomy. Significant intra-abdominal pressure elevations may occur in patients with extensive burns and are associated with a poorer prognosis. Elevation of intra-abdominal pressure should be considered in severely burned patients with oliguria, hypoventilation, or hypotension.

Abdomen↗
PubMed1994

The adequacy of limb escharotomies-fasciotomies after referral to a major burn center.

To determine the frequency of inadequate decompression and its complications, the medical records of 108 pediatric burn patients requiring escharotomies or fasciotomies were reviewed. Of 108 patients, 100 (93%) had escharotomies or fasciotomies performed at an outlying facility before transfer. Of these 100 patients, 44 (117 limbs) were inadequately decompressed and required further decompression after admission to our facility. Initial mean compartment pressures were 50.3 +/- 1.3 mm Hg, which were reduced to 16.3 +/- 0.5 mm Hg after decompression. Pulses were present in 74% of limbs requiring decompression. Twenty limbs required decompression despite noncircumferential burns. Complications of inadequate or delayed decompression included foot drop in 20 patients (35 limbs) and muscle necrosis in 13 patients (23 limbs). Four patients (seven limbs) required amputations because of progressive muscle necrosis and infection. Complications of the procedure itself were limited to bleeding in three patients. In conclusion, compartment pressures should be followed in patients with significant burns since pressures may increase over time and pulses are not predictive of ischemia. Failure to decompress extremities with elevated pressures leads to significant but preventable complications.

Burns↗
PubMed1994

Induction of keratinocyte growth factor expression is reduced and delayed during wound healing in the genetically diabetic mouse.

We have recently demonstrated induction of expression of several members of the fibroblast growth factor family during wound healing, particularly for keratinocyte growth factor, which was more than 150-fold induced within 24 h after injury. To assess whether wound-healing disorders are associated with a defect in fibroblast growth factor regulation, we have now investigated the expression of these mitogens as well as their receptors in normal and wounded skin of genetically diabetic db/db mice, which are characterized by their impaired wound healing. We demonstrate that induction of keratinocyte growth factor expression in these mice is significantly reduced and delayed compared to normal mice. Induction of acidic fibroblast growth factor (FGF) and basic FGF expression was earlier in diabetic mice than in normal mice, but by 3 d after injury expression of these mitogens had already returned to the basal levels. In contrast, elevated levels of acidic FGF and basic FGF transcripts were detected within the first 5 d in wounds from normal mice. Thus, FGFs seem to be expressed in a limited fashion in the wound tissue of db/db mice during the period when re-epithelialization and granulation tissue formation normally occur. These findings provide an explanation for the beneficial effect of exogenous FGF in the treatment of impaired wound healing in these animals and suggest that induction of KGF early in repair may be critical for the rapid re-epithelialization in normal wound healing.

Animals↗
PubMed1994

Improved ventilatory function in burn patients using volumetric diffusive respiration.

BACKGROUND: Volumetric diffusive respiration (VDR) offers theoretical advantages over conventional mechanical ventilation (CV) by using lower airway pressures, recruiting alveoli, and mobilizing secretions. STUDY DESIGN: Forty-eight thermally injured pediatric patients with failing respiratory status were changed from CV to VDR. Data were obtained just before transition for CV and after stabilization on VDR, within six hours of transition. RESULTS: Both ventilation and oxygenation were significantly improved with PaCO2 decreasing from 47 +/- 3 to 39 +/- 11 mm Hg and PaO2 increasing from 105 +/- 8 to 171 +/- 12 mm Hg after transition to VDR. Treatment with the VDR ventilator also resulted in a significant decrease in peak inspiratory pressures (PIP) from 52 +/- 2 to 38 +/- 2 cm H2O. The PaO2 to FiO2 ratio increased from 189 +/- 16 using CV, to 329 +/- 21 using VDR, suggesting an improvement in the ventilation and perfusion matching. Ventilatory efficiency, measured by the PaO2/FiO2/PIP ratio, greatly improved after transition from CV to VDR with fraction of inspired oxygen increasing from 3.9 +/- 0.4 to 10.3 +/- 1.0. Hemodynamic function (blood pressure and pulse rate) were not adversely affected by VDR. CONCLUSIONS: The VDR ventilator is more effective than conventional ventilation for maintaining optimal gas exchange at lower airway pressures in thermally injured pediatric patients.

Adolescent↗
PubMed1993

Skin anatomy and antigen expression after burn wound closure with composite grafts of cultured skin cells and biopolymers.

Closure of large skin wounds (i.e., burns, congenital giant nevus, reconstruction of traumatic injury) with split-thickness skin grafts requires extensive harvesting of autologous skin. Composite grafts consisting of collagen-glycosaminoglycan (GAG) substrates populated with cultured dermal fibroblasts and epidermal keratinocytes were tested in a pilot study on full-thickness burn wounds of three patients as an alternative to split-thickness skin. Light microscopy and transmission electron microscopy showed regeneration of epidermal and dermal tissue by 2 weeks, with degradation of the collagen-GAG implant associated with low numbers of leukocytes, and deposition of new collagen by fibroblasts. Complete basement membrane, including anchoring fibrils and anchoring plaques, is formed by 2 weeks, is mature by 3 months, and accounts for the absence of blistering of healed epidermis. All skin antigens tested (involucrin, filaggrin, laminin, collagens IV and VII, fibronectin, and chondroitin-sulfate) were expressed by 16 days after grafting. This cultured skin analogue provides an experimental alternative to split-thickness skin graft that develops histiotypic markers of skin anatomy and antigen expression after wound closure.

Adolescent↗
PubMed1993

PDGF and FGF reverse the healing impairment in protein-malnourished diabetic mice.

BACKGROUND: Growth factors have been shown to improve healing in impaired models but not after malnutrition. The effects of growth factors on altered tissue repair caused by malnutrition were examined. METHODS: Nondiabetic and diabetic mice fed a 1% protein diet received full-thickness skin wounds. Wounds were treated topically with vehicle, platelet-derived growth factor (PDGF, 10 micrograms) or basic fibroblast growth factor (bFGF, 1 microgram), for 5 days. RESULTS: Malnourished animals developed significantly impaired wound closure. PDGF or bFGF did not enhance closure in nondiabetic C57BL/KsJ-db/m mice, whether fed normal or restricted diets. The same treatment regimen was effective in reversing the delayed wound closure in their genetically diabetic C57BL/KsJ-db/db littermates. The growth factors significantly enhanced tissue repair in diabetic mice fed a 1% protein diet starting as early as day 15 and continuing until day 21. Protein-depleted diabetic wounds had significantly decreased cellularity and granulation tissue formation. These deficiencies were reversed with growth factor treatment. CONCLUSIONS: Despite the lack of effects in nondiabetic animals, growth factors improve healing in diabetic mice with restricted protein intake. The differential effects may result from different healing mechanisms: nondiabetic animals heal mainly by contraction; diabetic animals require granulation tissue formation and reepithelialization.

Animals↗
PubMed1992

Treatment of intra-abdominal infection with granulocyte colony-stimulating factor.

Polymicrobial infection is a significant cause of mortality in critically ill patients. Antibiotics and surgical intervention are useful but limited in their effectiveness for combating mixed infections. New prophylactic and therapeutic approaches are required to improve survival in critically ill patients. Neutrophils are a known primary host defense mechanism against bacterial infection. We evaluated the use of a neutrophil growth factor, recombinant human granulocyte colony-stimulating factor (G-CSF), to improve survival in a well-established sepsis model, cecal ligation and puncture (CLP). When administered beginning 4 days before CLP with injections continuing for 14 days after CLP, mice that received 10, 100, or 1000 ng of G-CSF had significantly improved survival compared with the control group. When treatment began at the time of CLP and continued for 7 days after CLP, G-CSF treatment resulted in a dose-dependent improvement in survival in groups that received 100, 500, or 1000 ng. The interaction of G-CSF and conventional antimicrobial therapy was evaluated by administration of G-CSF plus gentamicin. Mice received 100 ng of G-CSF beginning on day 1 before CLP with injections continuing for 3 days after CLP. Gentamicin-treated mice received a single 15 mg/kg injection of gentamicin at the time of CLP. Mice that received G-CSF alone or gentamicin alone had significantly improved survival compared with controls. Mice that received G-CSF plus gentamicin had improved survival compared with control mice and compared with mice that received G-CSF alone but not compared with mice that received gentamicin alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Activation of the rasHa gene in urethane-initiated papillomas induced by protocols with high and low frequencies of malignant conversion.

The number of papillomas that develop in mice initiated with a single exposure to urethane and promoted by repeated applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) is increased greater than 4-fold by pretreating the skin once with TPA 24 hr before administration of urethane. In contrast, the carcinoma incidence was increased only 2-fold by the TPA pretreatment. Individual papillomas developed from the two protocols, differing in the potential for conversion to malignancy, were compared for activation of the rasHa gene. An activated oncogene that transformed 3T3 cells was found in the DNA of four of five papillomas from urethane-initiated, TPA-promoted mice and in eight of eleven papillomas from similarly promoted mice exposed to TPA before urethane initiation. Southern analysis of DNA from tumors or 3T3 foci demonstrated that the rasHa gene was activated by an A----T transversion at the second base of codon 61 in all mutated alleles. Thus, tumors induced by the two protocols did not differ in rasHa activation.

3T3 Cells↗
PubMed1990

PDGF and FGF stimulate wound healing in the genetically diabetic mouse.

To examine the effects of recombinant growth factors in vivo, impaired wound healing was studied in genetically diabetic C57BL/KsJ-db/db mice. Large full-thickness skin wounds made on the backs of these mice exhibited significant delays in the entry of inflammatory cells into the wound, the formation of granulation tissue, and in wound closure when compared to their nondiabetic littermates. Recombinant human platelet-derived growth factor (rPDGF-BB, 1 or 10 micrograms), recombinant human basic fibroblast growth factor (rbFGF, 1 micrograms), or combinations of both were applied topically to the wounds for 5 to 14 days after wounding. Diabetic mouse wounds treated with rPDGF-BB or rbFGF had many more fibroblasts and capillaries in the wound bed at 10 and 21 days than did wounds treated with the vehicle alone. The animals treated with growth factors also had significantly greater wound closure at 21 days than those treated with the vehicle. Combinations of rPDGF-BB and rbFGF improved all parameters of healing but not to a greater extent than either growth factor alone. The effectiveness of rPDGF-BB and rbFGF suggest that recombinant growth factors may be useful in the treatment of patients with deficient wound repair.

Administration, Topical↗
PubMed1988

Do nutritional alterations contribute to adriamycin-induced impaired wound healing?

Adriamycin-impaired wound healing in mice was found to be related to the degree of weight loss which in turn was dependent on the dose given. Treated animals had an initial decrease in food consumption that correlated with initial weight loss. After approximately 7 days, food consumption returned to normal but the weight loss persisted. Both Adriamycin-treated mice and animals pair fed the amount of food consumed by drug-treated mice had wounds significantly weaker than control animals at 7 and 11 days. The Adriamycin-treated animals had 11-day wound strengths equal to or weaker than the pair fed group. By Day 14, the pair fed animals had wounds similar to those of controls but the Adriamycin-treated animals remained significantly weaker than the other groups. We feel that initially Adriamycin produces a short-term nutritional deficit that contributes to early wound healing impairment. Later, the toxicity of the drug predominates in altering wound repair.

Animals↗
PubMed1987

Is impaired wound healing caused by infection or nutritional depletion?

Since infection and malnutrition both impair wound repair, we examined the interactions of an intra-abdominal abscess and its nutritional alterations on wound healing. Mice subjected to a left paraspinal incision then underwent either cecal ligation and puncture (CLP) or sham operation (sham). Abscesses and an early decrease in food intake developed in all CLP mice, but the animals resumed normal food consumption by day 7. The CLP animals had an initial 20% weight loss; however, by day 11 they had a gradual return toward control weight. Fresh and formalin-fixed wound disruption strengths determined on days 7 through 35 revealed a significant weakness in CLP animals. To examine the role of nutritional intake, an additional set of experiments were performed with the following groups: CLP, sham, no operation (control), or sham operation with pair-feeding an amount equal to that consumed by the CLP group to reproduce only the nutritional deficit (sham/dep). At 7 and 11 days, fresh wound-disruption strengths of both CLP and sham/dep animals were significantly weaker than those of control or sham animals. A defect in formalin-fixed healing also existed for sham/dep mice at day 11. These findings suggest that short-term reduction in nutrient intake as a result of infection may be a major determinant of impaired wound healing.

Abscess↗
PubMedDate not supplied

Synergistic actions of platelet-derived growth factor and the insulin-like growth factors in vivo.

Topical application of growth factors has been shown to benefit both normal and impaired wound healing. In normal tissue repair, resident cells produce a "cocktail" of various types of growth factors that overlap in function. In vitro studies have proved that growth factor combinations can act synergistically to enhance cellular function beyond that achieved with individual growth factors. To determine whether similar combinations have a synergistic effect in vivo, we applied growth factor combinations topically to full-thickness skin wounds created in genetically diabetic mice. The C57BL/KsJ-db/db mouse is obese and has insulin-resistant diabetes, and it has been proved that this mouse has markedly impaired wound healing. Topical application of platelet-derived growth factor, insulin-like growth factor-I, or insulin-like growth factor-II enhances healing in this model. Marked synergism was found when platelet-derived growth factor and insulin-like growth factor-II were combined to produce augmentation in wound closure beyond that achieved by application of the individual growth factors. The synergistic effect allowed for improved tissue repair at doses of platelet-derived growth factor and insulin-like growth factor-II that were ineffective when applied individually. The addition of insulin-like growth factor-I or insulin to platelet-derived growth factor produced no significant synergism. Because multiple growth factors are released in the wound during the healing process, it is not surprising that their combination further enhances healing. Growth factor combinations should become an important addition to the armamentarium for the treatment of chronic, nonhealing wounds.

Journal Article↗
PubMedDate not supplied

Effects of basic fibroblast growth factor on the healing of partial-thickness donor sites. A prospective, randomized, double-blind trial.

A phase I/II clinical study was performed to evaluate the safety and potential efficacy of topical recombinant human basic fibroblast growth factor on the healing of partial-thickness skin graft donor sites in burned children. Each child served as his or her own control. In a blinded and random fashion, one donor site was sprayed with basic fibroblast growth factor (5 microg/cm(2)) on days 0 to 4 after harvest, whereas the other site was treated with vehicle. Twelve patients were entered in the study but one patient died of sepsis that was unrelated to growth factor treatment. Of the remaining 11 patients, no adverse events related to basic fibroblast growth factor occurred. Serum basic fibroblast growth factor levels were never detected and antibody levels remained unchanged. No differences in the rate of epithelialization or days until complete closure were noted (basic fibroblast growth factor = 12.9 +/- 3.9 days, placebo = 12.2 +/- 5.5 days; mean +/- standard error of the mean). No differences in pain, itching, wound fragility, erythema, scarring, or pigmentation were noted. All of the scars matured within 1 year with good to excellent results. Investigators, patients, or families could not distinguish between the two wounds. Although basic fibroblast growth factor proved safe, no enhancement of donor site healing was seen in this small study. Because the time for donor site healing limits subsequent autograft use in patients with sizeable burns, studies should focus on accelerating healing in patients with larger burns where donor site healing is delayed and reharvest is required.

Journal Article↗