Papers by Raquel Minasian
Plastic Amp Reconstructive Surgery, 2015
Injury to the skin can predispose individuals to invasive infection. The standard of care for inf... more Injury to the skin can predispose individuals to invasive infection. The standard of care for infected wounds is treatment with intravenous antibiotics. However, antibiotics delivered intravenously may have poor tissue penetration and be dose limited by systemic side effects. Topical delivery of antibiotics reduces systemic complications and delivers increased drug concentrations directly to the wound. Porcine full-thickness wounds infected with Staphylococcus aureus were treated with ultrahigh concentrations (over 1000 times the minimum inhibitory concentration) of gentamicin using an incubator-like wound healing platform. The aim of the present study was to evaluate clearance of infection and reduction in inflammation following treatment. Gentamicin cytotoxicity was evaluated by in vitro assays. Application of 2000 μg/ml gentamicin decreased bacterial counts in wound tissue from 7.2 ± 0.3 log colony-forming units/g to 2.6 ± 0.6 log colony-forming units/g in 6 hours, with no reduction observed in saline controls (p < 0.005). Bacterial counts in wound fluid decreased from 5.7 ± 0.9 log colony-forming units/ml to 0.0 ± 0 log colony-forming units/ml in 1 hour, with no reduction observed in saline controls (p < 0.005). Levels of interleukin-1β were significantly reduced in gentamicin-treated wounds compared with saline controls (p < 0.005). In vitro, keratinocyte migration and proliferation were reduced at gentamicin concentrations between 100 and 1000 μg/ml. Topical delivery of ultrahigh concentrations of gentamicin rapidly decontaminates acutely infected wounds and maintains safe systemic levels. Treatment of infected wounds using the proposed methodology protects the wound and establishes a favorable baseline for subsequent treatment.
Wound Repair and Regeneration, 2016
Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wou... more Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wound healing, delay in treatment, disability, or death. Traditional approach centers on early debridement, fluid resuscitation, and adjunct intravenous antibiotics. These modalities often prove inadequate in burns, where compromised local vasculature limits the tissue penetration of systemic antibiotics. Here, we demonstrate the treatment of infected burns with topical delivery of ultrahigh concentrations of antibiotics. Standardized burns were inoculated with Staphylococcus aureus or Pseudomonas aeruginosa. After debridement, burns were treated with either gentamicin (2 mg/mL) or minocycline (1 mg/mL) at concentrations greater than 1,000 times the minimum inhibitory concentration. Amount of bacteria was quantified in tissue biopsies and wound fluid following treatment. After six days of gentamicin or minocycline treatment, S. aureus counts decreased from 4.2 to 0.31 and 0.72 log CFU/g in tissue, respectively. Similarly, P. aeruginosa counts decreased from 2.5 to 0.0 and 1.5 log CFU/g in tissue, respectively. Counts of both S. aureus and P. aeruginosa remained at a baseline of 0.0 log CFU/mL in wound fluid for both treatment groups. The findings here demonstrate that super-therapeutic concentrations of antibiotics delivered topically can rapidly reduce bacterial counts in infected full-thickness porcine burns. This treatment approach may aid wound bed preparation and accelerate time to grafting. This article is protected by copyright. All rights reserved.
Advances in Wound Care, 2014
Significance: Fibroblasts play a critical role in normal wound healing. Various extracellular mat... more Significance: Fibroblasts play a critical role in normal wound healing. Various extracellular matrix (ECM) components, including collagens, fibrin, fibronectin, proteoglycans, glycosaminoglycans, and matricellular proteins, can be considered potent protagonists of fibroblast survival, migration, and metabolism. Recent Advances: Advances in tissue culture, tissue engineering, and ex vivo models have made the examination and precise measurements of ECM components in wound healing possible. Likewise, the development of specific transgenic animal models has created the opportunity to characterize the role of various ECM molecules in healing wounds. In addition, the recent characterization of new ECM molecules, including matricellular proteins, dermatopontin, and FACIT collagens (Fibril-Associated Collagens with Interrupted Triple helices), further demonstrates our cursory knowledge of the ECM in coordinated wound healing. Critical Issues: The manipulation and augmentation of ECM components in the healing wound is emerging in patient care, as demonstrated by the use of acellular dermal matrices, tissue scaffolds, and wound dressings or topical products bearing ECM proteins such as collagen, hyaluronan (HA), or elastin. Once thought of as neutral structural proteins, these molecules are now known to directly influence many aspects of cellular wound healing. Future Directions: The role that ECM molecules, such as CCN2, osteopontin, and secreted protein, acidic and rich in cysteine, play in signaling homing of fibroblast progenitor cells to sites of injury invites future research as we continue investigating the heterotopic origin of certain populations of fibroblasts in a healing wound. Likewise, research into differently sized fragments of the same polymeric ECM molecule is warranted as we learn that fragments of molecules such as HA and tenascin-C can have opposing effects on dermal fibroblasts.
Plastic and reconstructive surgery, 2015
Injury to the skin can predispose individuals to invasive infection. The standard of care for inf... more Injury to the skin can predispose individuals to invasive infection. The standard of care for infected wounds is treatment with intravenous antibiotics. However, antibiotics delivered intravenously may have poor tissue penetration and be dose limited by systemic side effects. Topical delivery of antibiotics reduces systemic complications and delivers increased drug concentrations directly to the wound. Porcine full-thickness wounds infected with Staphylococcus aureus were treated with ultrahigh concentrations (over 1000 times the minimum inhibitory concentration) of gentamicin using an incubator-like wound healing platform. The aim of the present study was to evaluate clearance of infection and reduction in inflammation following treatment. Gentamicin cytotoxicity was evaluated by in vitro assays. Application of 2000 μg/ml gentamicin decreased bacterial counts in wound tissue from 7.2 ± 0.3 log colony-forming units/g to 2.6 ± 0.6 log colony-forming units/g in 6 hours, with no reduct...
Burns, 2016
Porcine wounds closely mimic human wounds and are often used experimentally in burn studies. Mult... more Porcine wounds closely mimic human wounds and are often used experimentally in burn studies. Multiple burn devices have been reported but they rarely described precise amount of heat transfer and the burn devices generally have low and varying heat capacity resulting in significant and varying temperature drop. The authors developed a customized aluminum burn device with cork insulation and high heat capacity. A thermistor probe was embedded in the device to accurately measure the temperature of the aluminum. The burn injury was inflicted by preheating the burn device to 100°C and pressing on the dorsum of pig skin for different time points ranging from 5 to 30s using standardized force of 10N on the device. With the knowledge of the heat capacity of the aluminum block and the temperature drop, the amount of heat transferred can be calculated. The temperature drop was 0°C, 1°C, 2°C, 3°C and 5°C for a wound-device contact time of 5, 10, 15, 20 and 30s, respectively. The depths of injury at 72h after burn were 0.46mm, 0.82mm, 1.21mm, 1.61mm and 1.91mm at 5, 10, 15, 20 and 30s respectively. 3.1mm represented a full thickness burn. The depth of the burn wounds significantly correlated with the heat transferred per cm(2) (correlation coefficient=0.96, p-value=0.03). The authors describe a simple, standardized and reproducible animal burn model using a customized burn device. The high heat capacity ensures minimal temperature drop which minimizes the variability of heat transferred with a large temperature drop. The correlation between the heat transfer and the depth of injury can facilitate standardization of burn depths in future studies.
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Papers by Raquel Minasian