Effectiveness of a central line associated blood stream infection protocol in a pediatric population.

BACKGROUND: Central line associated bloodstream infections are a common cause of bacteremia and sepsis in pediatric patients with intestinal failure, secondary to long-term CVC use. METHODS: An IRB approved retrospective chart review was conducted on TPN-dependent patients with IF who had an identified CLABSI and presented to Children's of Alabama's emergency department (ED) and were admitted to the hospital. RESULTS: Forty-four patients were included in the study, 28 in the first 18-month period and 26 in the second, with 10 in both populations. After implementation, mean time from ED presentation to antibiotic ordered and ED admission to antibiotic administered were lower. Mean time between antibiotic administration and admission to the floor was greater, and number of infectious disease consultations was greater. Floor-ICU transfers were lower, readmissions within 30 days was similar, and mean length of stay was similar. CONCLUSION: A collaborative, multidiscipline-supported protocol for the care of patients with IF presenting to the ED enhances efficiency of antibiotic ordering/administration, as well as reduces the number of unplanned floor-ICU transfers.

Development of venous thrombi in a pediatric population of intestinal failure.

BACKGROUND/PURPOSE: Although pediatric intestinal failure (IF) is now a survivable diagnosis, children are still at risk for complications. Loss of venous access persists as a leading indication for intestinal transplantation. The goal of this study was to identify risk factors for loss of venous access in a pediatric intestinal failure population on long-term PN. METHODS: We identified all patients who were PN dependent. RESULTS: Patients that developed venous thrombosis had significantly more lines placed in the first 2 years of life compared to those who did not develop thrombosis. Multivariate regression analysis revealed that diagnosis (NEC and gastroschisis) and parental education were significant predictors of venous thrombosis. CONCLUSION: By identifying potential risk factors for thrombus development, interventions can be developed to improve the overall outcome in pediatric IF patients. TYPE OF STUDY: Diagnostic LEVEL OF EVIDENCE: III.

The percutaneous absorption of soman in a damaged skin porcine model and the evaluation of WoundStat™ as a topical decontaminant.

PURPOSE: The aim of this study was to evaluate a candidate haemostat (WoundStat™), down-selected from previous in vitro studies, for efficacy as a potential skin decontaminant against the chemical warfare agent pinacoyl methylfluorophosphonate (Soman, GD) using an in vivo pig model. MATERIALS AND METHODS: An area of approximately 3 cm2 was dermatomed from the dorsal ear skin to a nominal depth of 100 µm. A discrete droplet of 14C-GD (300 µg kg-1) was applied directly onto the surface of the damaged skin at the centre of the dosing site. Animals assigned to the treatment group were given a 2 g application of WoundStat™ 30 s after GD challenge. The decontamination efficacy of WoundStat™ against GD was measured by the direct quantification of the distribution of 14C-GD, as well as routine determination of whole blood cholinesterase and physiological measurements. RESULTS: WoundStat™ sequestered approximately 70% of the applied 14C-GD. Internal radiolabel recovery from treated animals was approximately 1% of the initially applied dose. Whole blood cholinesterase levels decreased to less than 10% of the original value by 15 min post WoundStat™ treatment and gradually decreased until the onset of apnoea or until euthanasia. All treated animals showed signs of GD intoxication that could be grouped into early (mastication, fasciculations and tremor), intermediate (miosis, salivation and nasal secretions) and late onset (lacrimation, body spasm and apnoea) effects. Two of the six WoundStat™ treated animals survived the study duration. CONCLUSIONS: The current study has shown that the use of WoundStat™ as a decontaminant on damaged pig ear skin was unable to fully protect against GD toxicity. Importantly, the findings indicate that the use of WoundStat™ in GD contaminated wounds would not exacerbate GD toxicity. These data suggest that absorbent haemostatic products may offer some limited functionality as wound decontaminants.

The percutaneous toxicokinetics of VX in a damaged skin porcine model and the evaluation of WoundStat™ as a topical decontaminant.

This study used a damaged skin, porcine model to evaluate the in vivo efficacy of WoundStat™ for the decontamination of superficial, nerve agent-contaminated wounds. Anaesthetized animals were randomly assigned to either control (n = 7), no decontamination (n = 12) or WoundStat™ (n = 12) treatment groups. Pigs were exposed to a 5× LD50 dose of neat, radiolabelled S-[2-(diisopropylamino)ethyl]-O-ethyl methyl-phosphonothioate (VX; or equivalent volume of sterile saline for the control group) via an area of superficially damaged skin on the ear. WoundStat™ was applied at 30 seconds post-exposure to assigned animals. The VX contaminant (or saline) and decontaminant remained in place for the duration of the study (up to 6 hours). Physiological parameters and signs of intoxication were recorded during the exposure period. Skin and organ samples were taken post mortem for 14 C-VX distribution analyses. Blood samples were taken periodically for toxicokinetic and whole-blood acetylcholinesterase (AChE) activity analyses. VX exposure was accompanied by a rapid decrease in AChE activity in all animals, regardless of decontamination. However, decontamination significantly improved survival rate and time and reduced the severity of signs of intoxication. In addition, the distribution of 14 C-VX in key internal organs and post mortem blood samples was significantly lower in the WoundStat™ treatment group. This study demonstrates that WoundStat™ may be a suitable medical countermeasure for increasing both survival rate and time following VX exposure. The results also suggest that AChE activity is not a useful prognostic indicator.

The percutaneous toxicokinetics of Sulphur mustard in a damaged skin porcine model and the evaluation of WoundStat™ as a topical decontaminant.

This study used a damaged skin, porcine model to evaluate the in vivo efficacy of WoundStat™ for decontamination of superficial (non-haemorrhaging), sulphur mustard-contaminated wounds. The dorsal skin of 12 female pigs was subjected to controlled physical damage and exposed to 10 µL 14 C-radiolabelled sulphur mustard (14 C-SM). Animals were randomly assigned to either a control or a treatment group. In the latter, WoundStat™ was applied 30 s post exposure and left in situ for 1 h. Skin lesion progression and decontaminant efficacy were quantified over 6 h using a range of biophysical measurements. Skin, blood and organ samples were taken post mortem for histopathological assessment, 14 C-SM distribution and toxicokinetic analyses. Application of SM to damaged skin without decontamination was rapidly followed by advanced signs of toxicity, including ulceration and decreased blood flow at the exposure site in all animals. WoundStat™ prevented ulceration and improved blood flow at the exposure site in all decontaminated animals (n = 6). Furthermore, significantly smaller quantities of 14 C-SM were detected in the blood (45% reduction), and recovered from skin (70% reduction) and skin surface swabs (99% reduction) at 6 h post-challenge. Overall, the distribution of 14 C-SM in the internal organs was similar for both groups, with the greatest concentration in the kidneys, followed by the liver and small intestine. WoundStat™ significantly reduced the amount of 14 C-SM recovered from the liver, a key organ for SM metabolism and detoxification. This study demonstrates that WoundStat™ is a suitable product for reducing the ingress and toxicity of a chemical warfare agent. Copyright © 2017 John Wiley & Sons, Ltd.

Development of haemostatic decontaminants for treatment of wounds contaminated with chemical warfare agents. 3: Evaluation of in vitro topical decontamination efficacy using damaged skin.

Previous studies have demonstrated that haemostatic products with an absorptive mechanism of action retain their clotting efficiency in the presence of toxic materials and are effective in decontaminating chemical warfare (CW) agents when applied to normal, intact skin. The purpose of this in vitro study was to assess three candidate haemostatic products for effectiveness in the decontamination of superficially damaged porcine skin exposed to the radiolabelled CW agents, soman (GD), VX and sulphur mustard (HD). Controlled physical damage (removal of the upper 100 µm skin layer) resulted in a significant enhancement of the dermal absorption of all three CW agents. Of the haemostatic products assessed, WoundStat™ was consistently the most effective, being equivalent in performance to a standard military decontaminant (fuller's earth). These data suggest that judicious application of haemostatic products to wounds contaminated with CW agents may be a viable option for the clinical management of casualties presenting with contaminated, haemorrhaging injuries. Further studies using a relevant animal model are required to confirm the potential clinical efficacy of WoundStat™ for treating wounds contaminated with CW agents. Copyright © 2017 John Wiley & Sons, Ltd.

Selection of non-steroidal anti-inflammatory drug and treatment regimen for sulfur mustard-induced cutaneous lesions.

The inflammatory process plays an important role in sulfur mustard (HD) injury and HD pathogenesis, suggesting that anti-inflammatory treatments applied as soon as possible following HD injury may reduce tissue damage and accelerate healing. This study used the HD dermal weanling swine model to investigate the efficacy of two non-steroidal anti-inflammatory drugs, capsaicin and diclofenac, when applied in combination with the steroid, clobetasol. The therapeutic regimen was also investigated with respect to initiation of treatment post-exposure, frequency and duration. Yorkshire-cross pigs were randomly assigned to experimental groups, corresponding to all combinations of treatment (capsaicin with clobetasol or diclofenac with clobetasol), onset time (1, 2 or 4 h post-exposure), treatment duration (1, 3 or 5 days) and frequency of applications (2, 3 or 4 per day). For each animal, two sites on the ventral abdomen were exposed to 400 µL of neat HD for 8 min to achieve superficial dermal (SD) lesions and two sites were exposed to 400 µL neat HD for 30 min to achieve deep dermal (DD) lesions. Each treatment regimen was tested against a SD and a DD injury. Untreated SD and DD lesion sites served as within-animal controls. Assessments, up to one week post-challenge, included digital photographs, clinical assessments (lesion size measurements and modified Draize scoring), transepidermal water loss (TEWL), reflectance colorimetry and histopathologic evaluations that included an estimate for depth of injury and wound healing parameters. Diclofenac plus clobetasol treatment resulted in significant reductions in lesion contracture and modified Draize scores, increased barrier function (decreased TEWL), and increased healing as determined by histopathology for both SD and DD injury when compared with untreated sites and sites treated with capsaicin plus clobetasol. An increased duration of treatment from 1 to 5 days was most commonly associated with decreased clinical assessment and histopathological severity scores. Therefore, a combination of diclofenac and clobetasol application, when administered for at least five days, shows promise in ameliorating HD-induced lesions.

DNA-Segment-Facilitated Dissociation of Fis and NHP6A from DNA Detected via Single-Molecule Mechanical Response.

The rate of dissociation of a DNA-protein complex is often considered to be a property of that complex, without dependence on other nearby molecules in solution. We study the kinetics of dissociation of the abundant Escherichia coli nucleoid protein Fis from DNA, using a single-molecule mechanics assay. The rate of Fis dissociation from DNA is strongly dependent on the solution concentration of DNA. The off-rate (k(off)) of Fis from DNA shows an initially linear dependence on solution DNA concentration, characterized by an exchange rate of k(ex)≈9×10(-4) (ng/µl)(-1) s(-1) for 100 mM univalent salt buffer, with a very small off-rate at zero DNA concentration. The off-rate saturates at approximately k(off,max)≈8×10(-3) s(-1) for DNA concentrations above ≈20 ng/µl. This exchange reaction depends mainly on DNA concentration with little dependence on the length of the DNA molecules in solution or on binding affinity, but this does increase with increasing salt concentration. We also show data for the yeast HMGB protein NHP6A showing a similar DNA-concentration-dependent dissociation effect, with faster rates suggesting generally weaker DNA binding by NHP6A relative to Fis. Our results are well described by a model with an intermediate partially dissociated state where the protein is susceptible to being captured by a second DNA segment, in the manner of "direct transfer" reactions studied for other DNA-binding proteins. This type of dissociation pathway may be important to protein-DNA binding kinetics in vivo where DNA concentrations are large.

Development of haemostatic decontaminants for the treatment of wounds contaminated with chemical warfare agents. 2: evaluation of in vitro topical decontamination efficacy using undamaged skin.

The risk of penetrating, traumatic injury occurring in a chemically contaminated environment cannot be discounted. Should a traumatic injury be contaminated with a chemical warfare (CW) agent, it is likely that standard haemostatic treatment options would be complicated by the need to decontaminate the wound milieu. Thus, there is a need to develop haemostatic products that can simultaneously arrest haemorrhage and decontaminate CW agents. The purpose of this study was to evaluate a number of candidate haemostats for efficacy as skin decontaminants against three CW agents (soman, VX and sulphur mustard) using an in vitro diffusion cell containing undamaged pig skin. One haemostatic product (WoundStat™) was shown to be as effective as the standard military decontaminants Fuller's earth and M291 for the decontamination of all three CW agents. The most effective haemostatic agents were powder-based and use fluid absorption as a mechanism of action to sequester CW agent (akin to the decontaminant Fuller's earth). The envisaged use of haemostatic decontaminants would be to decontaminate from within wounds and from damaged skin. Therefore, WoundStat™ should be subject to further evaluation using an in vitro model of damaged skin.

Development of haemostatic decontaminants for the treatment of wounds contaminated with chemical warfare agents. 1: evaluation of in vitro clotting efficacy in the presence of certain contaminants.

The treatment of penetrating, haemorrhaging injuries sustained within a hazardous environment may be complicated by contamination with toxic chemicals. There are currently no specific medical countermeasures for such injuries. Haemostats with an absorbent mechanism of action have the potential to simultaneously stop bleeding and decontaminate wounds. However, a primary requirement of a 'haemostatic decontaminant' is the retention of clotting function in the presence of chemical contaminants. Thus, the aim of this study was to investigate the haemostatic efficacy of seven commercially available haemostats in the presence of toxic chemicals (soman, VX, sulphur mustard, petrol, aviation fuel and motor oil). Clot viscosity was assessed ex vivo using thrombelastography following treatment of pig blood with: (i) toxic chemical; (ii) haemostat; or (iii) haemostat in combination with toxic chemical. Several contaminants (VX, petrol and GD) were found to be pro-haemostatic and none had an adverse effect on the rate with which the test products attained haemostasis. However, the total clot strength for blood treated with certain haemostats in the presence of sulphur mustard, soman and petrol was significantly decreased. Three test products failed to demonstrate haemostatic function in this ex vivo (thrombelastography) model; this was tentatively ascribed to the products achieving haemostasis through a tamponade mechanism of action, which can only be replicated using in vivo models. Overall, this study has identified a number of commercial products that may have potential as haemostatic decontaminants and warrant further investigation to establish their decontaminant efficacy.

Multi-platform compatible software for analysis of polymer bending mechanics.

Cytoskeletal polymers play a fundamental role in the responses of cells to both external and internal stresses. Quantitative knowledge of the mechanical properties of those polymers is essential for developing predictive models of cell mechanics and mechano-sensing. Linear cytoskeletal polymers, such as actin filaments and microtubules, can grow to cellular length scales at which they behave as semiflexible polymers that undergo thermally-driven shape deformations. Bending deformations are often modeled using the wormlike chain model. A quantitative metric of a polymer's resistance to bending is the persistence length, the fundamental parameter of that model. A polymer's bending persistence length is extracted from its shape as visualized using various imaging techniques. However, the analysis methodologies required for determining the persistence length are often not readily within reach of most biological researchers or educators. Motivated by that limitation, we developed user-friendly, multi-platform compatible software to determine the bending persistence length from images of surface-adsorbed or freely fluctuating polymers. Three different types of analysis are available (cosine correlation, end-to-end and bending-mode analyses), allowing for rigorous cross-checking of analysis results. The software is freely available and we provide sample data of adsorbed and fluctuating filaments and expected analysis results for educational and tutorial purposes.

A dynamic system for delivering controlled bromine and chlorine vapor exposures to weanling swine skin.

CONTEXT: Assessing the hazards of accidental exposure to toxic industrial chemical (TIC) vapors and evaluating therapeutic compounds or treatment regimens require the development of appropriate animal models. OBJECTIVE: The objective of this project was to develop an exposure system for delivering controlled vapor concentrations of TICs to the skin of anesthetized weanling pigs. Injury levels targeted for study were superficial dermal (SD) and deep dermal (DD) skin lesions as defined histopathologically. MATERIALS AND METHODS: The exposure system was capable of simultaneously delivering chlorine or bromine vapor to four, 3-cm diameter exposure cups placed over skin between the axillary and inguinal areas of the ventral abdomen. Vapor concentrations were generated by mixing saturated bromine or chlorine vapor with either dried dilution air or nitrogen. RESULTS: Bromine exposure concentrations ranged from 6.5 × 10(-4) to 1.03 g/L, and exposure durations ranged from 1 to 45 min. A 7-min skin exposure to bromine vapors at 0.59 g/L was sufficient to produce SD injuries, while a 17-min exposure produced a DD injury. Chlorine exposure concentrations ranged from 1.0 to 2.9 g/L (saturated vapor concentration) for exposures ranging from 3 to 90 min. Saturated chlorine vapor challenges for up to 30 min did not induce significant dermal injuries, whereas saturated chlorine vapor with wetted material on the skin surface for 30-60 min induced SD injuries. DD chlorine injuries could not be induced with this system. CONCLUSION: The vapor exposure system described in this study provides a means for safely regulating, quantifying and delivering TIC vapors to the skin of weanling swine as a model to evaluate therapeutic treatments.

Historical perspective on effects and treatment of sulfur mustard injuries.

Sulfur mustard (2,2'-dichlorodiethyl sulfide; SM) is a potent vesicating chemical warfare agent that poses a continuing threat to both military and civilian populations. Significant SM injuries can take several months to heal, necessitate lengthy hospitalizations, and result in long-term complications affecting the skin, eyes, and lungs. This report summarizes initial and ongoing (chronic) clinical findings from SM casualties from the Iran-Iraq War (1980-1988), with an emphasis on cutaneous injury. In addition, we describe the cutaneous manifestations and treatment of several men recently and accidentally exposed to SM in the United States. Common, chronic cutaneous problems being reported in the Iranian casualties include pruritis (the primary complaint), burning, pain, redness, desquamation, hyperpigmentation, hypopigmentation, erythematous papular rash, xerosis, multiple cherry angiomas, atrophy, dermal scarring, hypertrophy, and sensitivity to mechanical injury with recurrent blistering and ulceration. Chronic ocular problems include keratitis, photophobia, persistent tearing, sensation of foreign body, corneal thinning and ulceration, vasculitis of the cornea and conjunctiva, and limbal stem cell deficiency. Chronic pulmonary problems include decreases in lung function, bronchitis with hyper-reactive airways, bronchiolitis, bronchiectasis, stenosis of the trachea and other large airways, emphysema, pulmonary fibrosis, decreased total lung capacity, and increased incidences of lung cancer, pulmonary infections, and tuberculosis. There are currently no standardized or optimized methods of casualty management; current treatment strategy consists of symptomatic management and is designed to relieve symptoms, prevent infections, and promote healing. New strategies are needed to provide for optimal and rapid healing, with the goals of (a) returning damaged tissue to optimal appearance and normal function in the shortest period of time, and (b) ameliorating chronic effects. Further experimental research and clinical trials will be needed to prevent or mitigate the acute clinical effects of SM exposure and to reduce or eliminate the long-term manifestations.

Toxicogenomic analysis of chlorine vapor-induced porcine skin injury.

Chlorine is an industrial chemical that can cause cutaneous burns. Understanding the molecular mechanisms of tissue damage and wound healing is important for the selection and development of an effective post-exposure treatment. This study investigated the effect of cutaneous chlorine vapor exposure using a weanling swine burn model and microarray analysis. Ventral abdominal sites were exposed to a mean calculated chlorine vapor concentration of 2.9 g/L for 30 min. Skin samples were harvested at 1.5 h, 3 h, 6 h, and 24 h post-exposure and stored in RNAlater(®) until processing. Total RNA was isolated, processed, and hybridized to Affymetrix GeneChip(®) Porcine Genome Arrays. Differences in gene expression were observed with respect to sampling time. Ingenuity Pathways Analysis revealed seven common biological functions among the top ten functions of each time point, while canonical pathway analysis revealed 3 genes (IL-6, IL1A, and IL1B) were commonly shared among three significantly altered signaling pathways. The transcripts encoding all three genes were identified as common potential therapeutic targets for Phase II/III clinical trial, or FDA-approved drugs. The present study shows transcriptional profiling of cutaneous wounds induced by chlorine exposure identified potential targets for developing therapeutics against chlorine-induced skin injury.

Counting proteins bound to a single DNA molecule.

Chromosomes contain DNA covered with proteins performing functions such as architectural organization and transcriptional regulation. The ability to count the number of proteins bound to various regions of the genome is essential for understanding both architectural and regulatory functions. We present a straightforward method of counting gfp-conjugated proteins bound to an individual duplex DNA molecule by calibrating to a commercially available fluorescence standard using wide-field fluorescence microscopy. We demonstrate our method using the E. coli nucleoid-associated protein Fis.

Assembly of collagen fibril meshes using gold nanoparticles functionalized with tris(hydroxymethyl)phosphine-alanine as multivalent cross-linking agents.

We report on the use of tris(hydroxymethyl)phosphine-alanine (THPAL) functionalized gold nanoparticles as a multivalent cross-linking agent to assemble collagen fibrils into a mesh-like structure. Atomic force microscopy (AFM) was used for characterization of the structure after adsorption onto an atomically flat mica substrate, revealing a mesh-like construct in which the collagen fibrils and the gold nanoparticles interact to form interconnected nodes measuring from 100 to 500 nm. As expected, the density of the collagen mesh can be increased with a higher initial concentration of gold nanoparticles. The maximum thickness of the meshes (∼ 20 nm) obtained through cross-sectional height measurements confirms that the adsorbed structure consists of a single layer of collagen fibrils/gold nanoparticles assembled in two-dimensions. We propose that the capability of gold nanoparticles functionalized with the THPAL to bind to several collagen fibrils combined with the large persistence length of the fibrils, which was reported to be in the hundreds of nanometer range, are determinant factors for the preferential 2D growth of the mesh in solution.

An assessment of transcriptional changes in porcine skin exposed to bromine vapor.

Bromine is an industrial chemical that can cause severe cutaneous burns. This study was a preliminary investigation into the effect of cutaneous exposure to bromine vapor using a weanling swine burn model and microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.69 g L(-1) for 10 or 20 min. At 48 h postexposure, total RNA from skin samples was isolated, processed, and hybridized to Affymetrix GeneChip Porcine Genome Arrays. Expression analysis revealed that bromine vapor exposure for 10 or 20 min promoted similar transcriptional changes in the number of significantly modulated probe sets. A minimum of 83% of the probe sets was similar for both exposure times. Ingenuity pathways analysis revealed eight common biological functions among the top 10 functions of each experimental group, in which 30 genes were commonly shared among 19 significantly altered signaling pathways. Transcripts encoding heme oxygenase 1, interleukin-1ß, interleukin 2 receptor gamma chain, and plasminogen activator inhibitor-1 were identified as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study is an initial assessment of the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Temporal effects in porcine skin following bromine vapor exposure.

Bromine is an industrial chemical that causes severe cutaneous burns. When selecting or developing effective treatments for bromine burns, it is important to understand the molecular mechanisms of tissue damage and wound healing. This study investigated the effect of cutaneous bromine vapor exposure on gene expression using a weanling swine burn model by microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.51 g/L for 7 or 17 min. At 6 h, 48 h, and 7 days post-exposure, total RNA from skin samples was isolated, processed, and analyzed with Affymetrix GeneChip® Porcine Genome Arrays (N = 3 per experimental group). Differences in gene expression were observed with respect to exposure duration and sampling time. Ingenuity Pathways Analysis (IPA) revealed four common biological functions (cancer, cellular movement, cell-to-cell signaling and interaction, and tissue development) among the top ten functions of each experimental group, while canonical pathway analysis revealed 9 genes (ARG2, CCR1, HMOX1, ATF2, IL-8, TIMP1, ESR1, HSPAIL, and SELE) that were commonly shared among four significantly altered signaling pathways. Among these, the transcripts encoding HMOX1 and ESR1 were identified using IPA as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study describes the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Concentration-dependent exchange accelerates turnover of proteins bound to double-stranded DNA.

The multistep kinetics through which DNA-binding proteins bind their targets are heavily studied, but relatively little attention has been paid to proteins leaving the double helix. Using single-DNA stretching and fluorescence detection, we find that sequence-neutral DNA-binding proteins Fis, HU and NHP6A readily exchange with themselves and with each other. In experiments focused on the Escherichia coli nucleoid-associated protein Fis, only a small fraction of protein bound to DNA spontaneously dissociates into protein-free solution. However, if Fis is present in solution, we find that a concentration-dependent exchange reaction occurs which turns over the bound protein, with a rate of k(exch) = 6 × 10(4) M(-1)s(-1). The bacterial DNA-binding protein HU and the yeast HMGB protein NHP6A display the same phenomenon of protein in solution accelerating dissociation of previously bound labeled proteins as exchange occurs. Thus, solvated proteins can play a key role in facilitating removal and renewal of proteins bound to the double helix, an effect that likely plays a major role in promoting the turnover of proteins bound to DNA in vivo and, therefore, in controlling the dynamics of gene regulation.

Transcriptional changes in porcine skin at 7 days following sulfur mustard and thermal burn injury.

Severe cutaneous injuries continue to result from exposure to sulfur mustard [bis(2-chloroethyl)sulfide; HD] and thermal burns. Microarray analysis was utilized in this study to evaluate transcriptional changes in porcine skin assessing the underlying repair mechanisms of HD and thermal injury involved in wound healing. Four ventral abdominal sites on each of 4 weanling swine were exposed to 400 microL undiluted HD or a heated brass rod (70 degrees C) for 8 minutes and 45-60 seconds, respectively. At 7 days postexposure, skin samples were excised and total RNA was isolated, labeled, and hybridized to Affymetrix GeneChip (Santa Clara, CA, USA) Porcine Genome Arrays (containing 20,201 genes). Based on the gene expression patterns in HD- and thermal-exposed skin at 7 days, the transcriptional profiles do not differ greatly. HD and thermal exposures promoted similar changes in transcription, where 270 and 283 transcripts were increased with HD and thermal exposures, respectively. Both exposures promoted decreases in 317 and 414 transcripts, respectively. Of the significantly increased transcripts, at least 77% were commonly expressed in both HD- and thermal-exposed skin, whereas at least 67% of decreased transcripts were common between both exposure types. Six of the top 10 biological functions were common to HD and thermal injury in which 9 canonical pathways were shared. The present study illustrates the similarities found between HD and thermal injury with respect to transcriptional response and wound healing and identifies specific genes (CXCL2, CXCR4, FGFR2, HMOX1, IGF1, PF4, PLAU, PLAUR, S100A8, SPP1, and TNC) that may be useful as potential therapeutic targets to promote improved wound healing.