Acetylated lysine 56 on histone H3 drives chromatin assembly after repair and signals for the completion of repair.

DNA damage causes checkpoint activation leading to cell cycle arrest and repair, during which the chromatin structure is disrupted. The mechanisms whereby chromatin structure and cell cycle progression are restored after DNA repair are largely unknown. We show that chromatin reassembly following double-strand break (DSB) repair requires the histone chaperone Asf1 and that absence of Asf1 causes cell death, as cells are unable to recover from the DNA damage checkpoint. We find that Asf1 contributes toward chromatin assembly after DSB repair by promoting acetylation of free histone H3 on lysine 56 (K56) via the histone acetyl transferase Rtt109. Mimicking acetylation of K56 bypasses the requirement for Asf1 for chromatin reassembly and checkpoint recovery, whereas mutations that prevent K56 acetylation block chromatin reassembly after repair. These results indicate that restoration of the chromatin following DSB repair is driven by acetylated H3 K56 and that this is a signal for the completion of repair.

Calorie restriction and SIRT3 trigger global reprogramming of the mitochondrial protein acetylome.

Calorie restriction (CR) extends life span in diverse species. Mitochondria play a key role in CR adaptation; however, the molecular details remain elusive. We developed and applied a quantitative mass spectrometry method to probe the liver mitochondrial acetyl-proteome during CR versus control diet in mice that were wild-type or lacked the protein deacetylase SIRT3. Quantification of 3,285 acetylation sites-2,193 from mitochondrial proteins-rendered a comprehensive atlas of the acetyl-proteome and enabled global site-specific, relative acetyl occupancy measurements between all four experimental conditions. Bioinformatic and biochemical analyses provided additional support for the effects of specific acetylation on mitochondrial protein function. Our results (1) reveal widespread reprogramming of mitochondrial protein acetylation in response to CR and SIRT3, (2) identify three biochemically distinct classes of acetylation sites, and (3) provide evidence that SIRT3 is a prominent regulator in CR adaptation by coordinately deacetylating proteins involved in diverse pathways of metabolism and mitochondrial maintenance.

Porcine Xenograft and Epidermal Fully Synthetic Skin Substitutes in the Treatment of Partial-Thickness Burns: A Literature Review.

Background and Objectives: Porcine xenografts have been used successfully in partial thickness burn treatment for many years. Their disappearance from the market led to the search for effective and efficient alternatives. In this article, we examine the synthetic epidermal skin substitute Suprathel® as a substitute in the treatment of partial thickness burns. Materials and Methods: A systematic review following the PRISMA guidelines has been performed. Sixteen Suprathel® and 12 porcine xenograft studies could be included. Advantages and disadvantages between the treatments and the studies' primary endpoints have been investigated qualitatively and quantitatively. Results: Although Suprathel had a nearly six times larger TBSA in their studies (p < 0.001), it showed a significantly lower necessity for skin grafts (p < 0.001), and we found a significantly lower infection rate (p < 0.001) than in Porcine Xenografts. Nonetheless, no significant differences in the healing time (p = 0.67) and the number of dressing changes until complete wound healing (p = 0.139) could be found. Both products reduced pain to various degrees with the impression of a better performance of Suprathel® on a qualitative level. Porcine xenograft was not recommended for donor sites or coverage of sheet-transplanted keratinocytes, while Suprathel® was used successfully in both indications. Conclusion: The investigated parameters indicate that Suprathel® to be an effective replacement for porcine xenografts with even lower subsequent treatment rates. Suprathel® appears to be usable in an extended range of indications compared to porcine xenograft. Data heterogeneity limited conclusions from the results.

Cardiorespiratory Capacity and Strength Remain Attenuated in Children with Severe Burn Injuries at Over 3 Years Postburn.

OBJECTIVES: To compare physical capacity and body composition between children with burn injuries at approximately 4 years postburn and healthy, fit children. STUDY DESIGN: In this retrospective, case-control study, we analyzed the strength, aerobic capacity, and body composition of children with severe burn injuries (n = 40) at discharge, after completion of a 6- to 12-week rehabilitative exercise training program, and at 3-4 years postburn. Values were expressed as a relative percentage of those in age- and sex-matched children for comparison (n = 40 for discharge and postexercise; n = 40 for 3.5 years postburn). RESULTS: At discharge, lean body mass was 89% of that in children without burn injuries, and exercise rehabilitation restored this to 94% (P < .01). At 3.5 years postburn, lean body mass (94%), bone mineral content (89%), and bone mineral density (93%; each P ≤ .02) remained reduced, whereas total body fat was increased (148%, P = .01). Cardiorespiratory fitness remained lower in children with burn injuries both after exercise training (75%; P < .0001) and 3.5 years later (87%; P < .001). Peak torque (60%; P < .0001) and average power output (58%; P < .0001) were lower after discharge. Although exercise training improved these, they failed to reach levels achieved in healthy children without burns (83-84%; P < .0001) but were maintained at 85% and 82%, respectively, 3.5 years later (P < .0001). CONCLUSIONS: Although the benefits of rehabilitative exercise training on strength and cardiorespiratory capacity are maintained at almost 4 years postburn, they are not restored fully to the levels of healthy children. Although the underlying mechanism of this phenomenon remains elusive, these findings suggest that future development of continuous exercise rehabilitation interventions after discharge may further narrow the gap in relation to healthy adolescents.

Elevated histone expression promotes life span extension.

Changes to the chromatin structure accompany aging, but the molecular mechanisms underlying aging and the accompanying changes to the chromatin are unclear. Here, we report a mechanism whereby altering chromatin structure regulates life span. We show that normal aging is accompanied by a profound loss of histone proteins from the genome. Indeed, yeast lacking the histone chaperone Asf1 or acetylation of histone H3 on lysine 56 are short lived, and this appears to be at least partly due to their having decreased histone levels. Conversely, increasing the histone supply by inactivation of the histone information regulator (Hir) complex or overexpression of histones dramatically extends life span via a pathway that is distinct from previously known pathways of life span extension. This study indicates that maintenance of the fundamental chromatin structure is critical for slowing down the aging process and reveals that increasing the histone supply extends life span.

Quantification of mitochondrial acetylation dynamics highlights prominent sites of metabolic regulation.

Lysine acetylation is rapidly becoming established as a key post-translational modification for regulating mitochondrial metabolism. Nonetheless, distinguishing regulatory sites from among the thousands identified by mass spectrometry and elucidating how these modifications alter enzyme function remain primary challenges. Here, we performed multiplexed quantitative mass spectrometry to measure changes in the mouse liver mitochondrial acetylproteome in response to acute and chronic alterations in nutritional status, and integrated these data sets with our compendium of predicted Sirt3 targets. These analyses highlight a subset of mitochondrial proteins with dynamic acetylation sites, including acetyl-CoA acetyltransferase 1 (Acat1), an enzyme central to multiple metabolic pathways. We performed in vitro biochemistry and molecular modeling to demonstrate that acetylation of Acat1 decreases its activity by disrupting the binding of coenzyme A. Collectively, our data reveal an important new target of regulatory acetylation and provide a foundation for investigating the role of select mitochondrial protein acetylation sites in mediating acute and chronic metabolic transitions.

A phase 3b, open-label, single-arm, multicenter, expanded-access study of the safety and clinical outcomes of StrataGraft® treatment in adults with deep partial-thickness thermal burns.

BACKGROUND: A phase 3b, open-label, multicenter, expanded-access study (NCT04123548) evaluated safety and clinical outcomes of StrataGraft treatment in adults with deep partial-thickness thermal burns with intact dermal elements. METHODS: Adult patients with 3 % to < 50 % total body surface area burns were treated with a single application of ≤ 1:1 meshed StrataGraft and followed for 24 weeks. Primary endpoint was count and percentage of patients with treatment-emergent adverse events (TEAEs). Secondary endpoints included confirmed wound closure (WC) at Week 12, durable WC at Week 24, time to WC, scar evaluation, and wound infection-related events. RESULTS: Fifty-two patients with 96 treatment sites were enrolled. Pruritus was the most common TEAE (22 patients [42.3 %]). Twenty serious TEAEs occurred in 10 patients (19.2 %); none were related to StrataGraft. There were 4 (7.7 %) deaths (aspiration, myocardial infarction, self-injury, Gram-negative rod sepsis); none were related to StrataGraft. Confirmed WC was achieved by Week 12 in 33 patients (63.5 %; 95 % CI: 50.4-76.5 %) and 69 treatment sites (71.9 %; 95 % CI: 62.9-80.9 %). Durable WC was achieved by Week 24 in 29 patients (55.8 %; 95 % CI: 42.3-69.3 %) and 58 treatment sites (60.4 %; 95 % CI: 50.6-70.2 %). CONCLUSIONS: StrataGraft demonstrated clinical benefit. Safety data were consistent with previously reported findings.

Experience with Implementing a Beta-lactam Therapeutic Drug Monitoring Service in a Burn Intensive Care Unit: A Retrospective Chart Review.

Thermal injuries alter pharmacokinetics, complicating the prediction of standard antibiotic dose effectiveness. Therapeutic drug monitoring (TDM) has been proposed to prevent subtherapeutic dosing of antibiotic therapy, but remains scarcely studied in the burn patient population. A retrospective chart review of burn patients receiving beta-lactam TDM from 2016 to 2019 was conducted. Adult patients with thermal injury receiving cefepime, piperacillin/tazobactam, or meropenem for ≥48 hours were included. Between February 2016 and July 2017, we utilized selective TDM based on clinical judgement to guide treatment. From October 2018 until July 2019, TDM was expanded to all burn patients on beta-lactams. The primary endpoint was achievement of therapeutic concentration, and the secondary endpoints were clinical cure, culture clearance, new resistance, length of stay, and mortality. The selective (control) group included 19 patients and the universal (study) group reviewed 23 patients. In both groups, skin and lungs were the most common primary infection sources, with Pseudomonas aeruginosa as the most common species. In the universal cohort, patients were older with higher risk factors, but more frequently achieved the target drug concentration, required less days to start TDM (p < .0001), and had more frequent measurements and beta-lactam dose adjustments. Positive clinical outcome was reported in 77%, and microbial eradication in 82% of all patients. All clinical outcomes were similar between the groups. The implementation of beta-lactam TDM protocol shortened the time, increased the probability of appropriate target attainment, and individualized beta-lactam therapy in burn patients.

Clinical Practice Guideline: Early Mobilization and Rehabilitation of Critically Ill Burn Patients.

This Clinical Practice Guideline addresses early mobilization and rehabilitation (EMR) of critically ill adult burn patients in an intensive care unit (ICU) setting. We defined EMR as any systematic or protocolized intervention that could include muscle activation, active exercises in bed, active resistance exercises, active side-to-side turning, or mobilization to sitting at the bedside, standing, or walking, including mobilization using assistance with hoists or tilt tables, which was initiated within at least 14 days of injury, while the patient was still in an ICU setting. After developing relevant PICO (Population, Intervention, Comparator, Outcomes) questions, a comprehensive literature search was conducted with the help of a professional medical librarian. Available literature was reviewed and systematically evaluated. Recommendations were formulated through the consensus of a multidisciplinary committee, which included burn nurses, physicians, and rehabilitation therapists, based on the available scientific evidence. No recommendation could be formed on the use of EMR to reduce the duration of mechanical ventilation in the burn ICU, but we conditionally recommend the use of EMR to reduce ICU-acquired weakness in critically ill burn patients. No recommendation could be made regarding EMR's effects on the development of hospital-acquired pressure injuries or disruption or damage to the skin grafts and skin substitutes. We conditionally recommend the use of EMR to reduce delirium in critically ill burn patients in the ICU.

Analysis of real-world length of stay data and costs associated with use of autologous skin cell suspension for the treatment of small burns in U.S. centers.

BACKGROUND: Autologous skin cell suspension (ASCS) is a treatment for acute thermal burn injuries associated with significantly lower donor skin requirements than conventional split-thickness skin grafts (STSG). Projections using the BEACON model suggest that among patients with small burns (total body surface area [TBSA]<20 %), use of ASCS± STSG leads to a shorter length of stay (LOS) in hospital and cost savings compared with use of STSG alone. This study evaluated whether data from real-world clinical practice corroborate these findings. MATERIALS AND METHODS: Electronic medical record data were collected from January 2019 through August 2020 from 500 healthcare facilities in the United States. Adult patients receiving inpatient treatment with ASCS± STSG for small burns were identified and matched to patients receiving STSG using baseline characteristics. LOS was assumed to cost $7554/day and to account for 70 % of overall costs. Mean LOS and costs were calculated for the ASCS± STSG and STSG cohorts. RESULTS: A total of 151 ASCS± STSG and 2243 STSG cases were identified; 63.0 % of patients were male and the average age was 44.2 years. Sixty-three matches were made between cohorts. LOS was 18.5 days with ASCS± STSG and 20.6 days with STSG (difference: 2.1 days [10.2 %]). This difference led to bed cost savings of $15,587.62 per ASCS± STSG patient. Overall cost savings with ASCS± STSG were $22,268.03 per patient. CONCLUSIONS: Analysis of real-world data shows that treatment of small burn injuries with ASCS± STSG provides reduced LOS and substantial cost savings compared with STSG, supporting the validity of the BEACON model projections.

Flexible CO2 laser and submucosal gel injection for safe endoluminal resection in the intestines.

BACKGROUND: The CO(2) laser's unique wavelength of 10.6 µm has the advantage of being readily absorbed by water but historically limited it to line-of-sight procedures. Through recent technological advances, a flexible CO(2) laser fiber has been developed and holds promise for endoluminal surgery. We examined whether this laser, along with injection of a water-based gel in the submucosal space, will allow safe dissection of the intestines and enhance the potential of this tool for minimally invasive surgery. METHODS: Using an ex vivo model with porcine intestines, spot ablation was performed with the flexible CO(2) laser at different power settings until transmural perforation. Additionally, excisions of mucosal patches were performed by submucosal dissection with and without submucosal injection of a water-based gel. RESULTS: With spot ablation at 5 W, none of the specimens was perforated by 5 min, which was the maximum recorded time. The time to perforation was significantly shorter with increased laser power, and gel pretreatment protected the intestines against spot ablation, increasing the time to perforation from 6 to 37 s at 10 W and from 1 to 7 s at 15 W. During excision of mucosal patches, 56 and 83% of untreated intestines perforated at 5 and 10 W, respectively. Gel pretreatment prior to excision protected all intestines against perforation. These specimens were verified to be intact by inflation with air to over 100 mmHg. Furthermore, excision of the mucosal patch was complete in gel-pretreated specimens, whereas 22% of untreated specimens had residual islands of mucosa after excision. CONCLUSION: The flexible CO(2) laser holds promise as a precise dissection and cutting tool for endoluminal surgery of the intestines. Pretreatment with a submucosal injection of a water-based gel protects the intestines from perforation during ablation and mucosal dissection.

Length of Stay and Costs with Autologous Skin Cell Suspension Versus Split-Thickness Skin Grafts: Burn Care Data from US Centers.

INTRODUCTION: Autologous skin cell suspension (ASCS) significantly reduces donor skin requirements versus conventional split-thickness skin grafts (STSG) for thermal burn treatment. In analyses using the Burn-medical counter measure Effectiveness Assessment Cost Outcomes Nexus (BEACON) model, ASCS was associated with shorter hospital length of stay (LOS) and cost savings versus STSG. This study hypothesized that daily practice data from the USA would support these findings. METHODS: Electronic medical record data from 500 healthcare facilities (January 2019-August 2020) were used to match adult patients who received inpatient burn treatment with ASCS (± STSG) to patients treated with STSG alone on the basis of sex, age, percent total body surface area (TBSA), and comorbidities. Based on BEACON analyses, LOS was assumed to represent 70% of total costs and used as a proxy to assess the data. Mean LOS, costs, and the incremental revenue associated with inpatient capacity changes were calculated. RESULTS: A total of 151 ASCS and 2443 STSG patients were identified: 63.0% were male and average age was 44.5 years. Eight-one matches were made between cohorts. LOS was 21.7 days with ASCS and 25.0 days with STSG alone (difference 3.3 days [13.2%]). LOS was lower with ASCS than STSG in four of five TBSA intervals. The LOS difference led to hospital bed cost savings of $25,864 per ASCS patient; overall cost savings were $36,949 per patient. Similar cost savings were observed in TBSA groupings < 20% and ≥ 20%. The reduced LOS with ASCS translated into an increased capacity of 2.2 inpatients/bed annually, which increased hospital revenue by $92,283/burn unit bed annually. CONCLUSIONS: Real-world data show that ASCS (± STSG) is associated with reduced LOS and cost savings versus STSG alone across all burn sizes, supporting the validity of the BEACON analyses. ASCS use may also increase patient capacity and throughput, leading to increased hospital revenue.

Autologous skin cell suspension (ASCS) is a treatment for thermal skin burn injuries that can be used alone or in combination with split-thickness skin grafts (STSG), the conventional standard of care. Projections using the Burn-medical counter measure Effectiveness Assessment Cost Outcomes Nexus (BEACON) model indicate that ASCS leads to shorter hospital length of stay (LOS) and overall cost savings compared with STSG alone. These model findings are supported by benchmarking study data from a limited sample of US burn centers. The current study aimed to understand whether the BEACON projections are supported by daily clinical practice data from US healthcare facilities. Using electronic medical record data, we matched patients who received ASCS ± STSG from January 2019 to August 2020 to those receiving STSG alone on the basis of demographic and clinical factors. Data analysis showed that hospital LOS was shorter (3.3 days) with ASCS ± STSG than STSG alone, a difference associated with a hospital bed cost savings of $25,864 per ASCS patient. Overall cost savings, which included nursing time and other costs, were $36,949 per patient. Analysis of patients with burns comprising total body surface areas less than 20% or at least 20% showed cost savings in both groups. The reduced LOS with ASCS also translated into the ability to treat 2.2 more patients per hospital bed per year, which was projected to increase hospital earnings. These real-world findings support those of modeling analyses, indicating that use of ASCS ± STSG is associated with meaningful clinical and economic benefits compared with use of STSG alone.

Insertion of the human sodium iodide symporter to facilitate deep tissue imaging does not alter oncolytic or replication capability of a novel vaccinia virus.

INTRODUCTION: Oncolytic viruses show promise for treating cancer. However, to assess therapeutic efficacy and potential toxicity, a noninvasive imaging modality is needed. This study aimed to determine if insertion of the human sodium iodide symporter (hNIS) cDNA as a marker for non-invasive imaging of virotherapy alters the replication and oncolytic capability of a novel vaccinia virus, GLV-1h153. METHODS: GLV-1h153 was modified from parental vaccinia virus GLV-1h68 to carry hNIS via homologous recombination. GLV-1h153 was tested against human pancreatic cancer cell line PANC-1 for replication via viral plaque assays and flow cytometry. Expression and transportation of hNIS in infected cells was evaluated using Westernblot and immunofluorescence. Intracellular uptake of radioiodide was assessed using radiouptake assays. Viral cytotoxicity and tumor regression of treated PANC-1tumor xenografts in nude mice was also determined. Finally, tumor radiouptake in xenografts was assessed via positron emission tomography (PET) utilizing carrier-free 124I radiotracer. RESULTS: GLV-1h153 infected, replicated within, and killed PANC-1 cells as efficiently as GLV-1h68. GLV-1h153 provided dose-dependent levels of hNIS expression in infected cells. Immunofluorescence detected transport of the protein to the cell membrane prior to cell lysis, enhancing hNIS-specific radiouptake (P < 0.001). In vivo, GLV-1h153 was as safe and effective as GLV-1h68 in regressing pancreatic cancer xenografts (P < 0.001). Finally, intratumoral injection of GLV-1h153 facilitated imaging of virus replication in tumors via 124I-PET. CONCLUSION: Insertion of the hNIS gene does not hinder replication or oncolytic capability of GLV-1h153, rendering this novel virus a promising new candidate for the noninvasive imaging and tracking of oncolytic viral therapy.

Pseudomonal Meningoencephalitis With Ventriculitis Secondary to Bacteremia in a Burn Patient: A Novel Case.

Burn patients with large burn surface area involvement are at increased risk of infection due to the presence of large wounds, multiple surgeries, prolonged intensive care unit admission, and immunosuppression. Pseudomonas aeruginosa is the most commonly isolated organism in this population. Even with frequent infections in the burn population, meningitis and encephalitis are rare, and ventriculitis is exceptional. We report the case of a 66-year-old woman who developed P. aeruginosa bacteremia during her hospital course, causing secondary meningoencephalitis with ventriculitis. She was admitted for partial- and full-thickness burns affecting the neck, chest, abdomen, upper medial arms, and bilateral anteromedial thighs for an estimated 20% total body surface area burn. She met sepsis criteria and broad-spectrum antimicrobial coverage was initiated. Magnetic resonance imaging of the brain, performed for altered mental status, revealed meningitis and ventriculitis. Cerebrospinal fluid analysis demonstrated findings consistent with bacterial meningitis, with cultures positive for P. aeruginosa. Serial neuroimaging with computerized tomography revealed new areas of ischemia concerning for septic emboli. In the presence of altered mental status and fever of unknown origin, workup should remain broad. Even in the presence of another source, it is important to keep an open mind for the rarer intracerebral infection as it requires different management, including urgent evaluation of antibiotic selection and dosing to ensure central nervous system penetration, and neurosurgical evaluation.

A phase 3, open-label, controlled, randomized, multicenter trial evaluating the efficacy and safety of StrataGraft® construct in patients with deep partial-thickness thermal burns.

OBJECTIVE: This phase 3 study evaluated StrataGraft construct as a donor-site sparing alternative to autograft in patients with deep partial-thickness (DPT) burns. METHODS: Patients aged ≥18 years with 3-49% total body surface area (TBSA) thermal burns were enrolled. In each patient, 2 DPT areas (≤2000cm2 total) of comparable depth after excision were randomized to either cryopreserved StrataGraft or autograft. Coprimary endpoints were: the difference in percent area of StrataGraft treatment site and autograft treatment site autografted at Month 3 (M3), and the proportion of patients achieving durable wound closure of the StrataGraft site without autograft at M3. Safety assessments were performed in all patients. Efficacy and safety follow-up continued to 1 year. RESULTS: Seventy-one patients were enrolled. By M3, there was a 96% reduction in mean percent area of StrataGraft treatment sites that required autografting, compared with autograft treatment sites (4.3% vs 102.1%, respectively; P<.0001). StrataGraft treatment resulted in durable wound closure at M3 without autografting in 92% (95% CI: 85.6, 98.8; n/n 59/64) of patients for whom data were available. The most common StrataGraft-related adverse event was pruritus (15%). CONCLUSIONS: Both coprimary endpoints were achieved. StrataGraft may offer a new treatment for DPT burns to reduce the need for autografting. CLINICAL TRIAL IDENTIFIER: NCT03005106.

Results of a Multicenter Feasibility Study of an Automated Bedside Glucose Monitoring System in the Burn Intensive Care Setting.

Intensive blood glucose regimens required for tight glycemic control in critically ill burn patients carry risk of hypoglycemia and are ultimately limited by the frequency of which serum glucose measurements can be feasibly monitored. Continuous inline glucose monitoring has the potential to significantly increase the frequency of serum glucose measurement. The objective of this study was to assess the accuracy of a continuous glucose monitor with inline capability (Optiscanner) in the burn intensive care setting. A multicenter, observational study was conducted at two academic burn centers. One hundred and six paired blood samples were collected from 10 patients and measured on the Optiscanner and the Yellow Springs Instrument. Values were plotted on a Clarke Error Grid and mean absolute relative difference calculated. Treatment was guided by existing hospital protocols using separately obtained values. 97.2% of results obtained from Optiscanner were within 25% of corresponding Yellow Springs Instrument values and 100% were within 30%. Mean absolute relative difference was calculated at 9.6%. Our findings suggest that a continuous glucose monitor with inline capability provides accurate blood glucose measurements among critically ill burn patients.

American Burn Association Guidelines on the Management of Acute Pain in the Adult Burn Patient: A Review of the Literature, a Compilation of Expert Opinion, and Next Steps.

The ABA pain guidelines were developed 14 years ago and have not been revised despite evolution in the practice of burn care. A sub-committee of the American Burn Association's Committee on the Organization and Delivery of Burn Care was created to revise the adult pain guidelines. A MEDLINE search of English-language publications from 1968 to 2018 was conducted using the keywords "burn pain," "treatment," and "assessment." Selected references were also used from the greater pain literature. Studies were graded by two members of the committee using Oxford Centre for Evidence-based Medicine-Levels of Evidence. We then met as a group to determine expert consensus on a variety of topics related to treating pain in burn patients. Finally, we assessed gaps in the current knowledge and determined research questions that would aid in providing better recommendations for optimal pain management of the burn patient. The literature search produced 189 papers, 95 were found to be relevant to the assessment and treatment of burn pain. From the greater pain literature 151 references were included, totaling 246 papers being analyzed. Following this literature review, a meeting to establish expert consensus was held and 20 guidelines established in the areas of pain assessment, opioid medications, nonopioid medications, regional anesthesia, and nonpharmacologic treatments. There is increasing research on pain management modalities, but available studies are inadequate to create a true standard of care. We call for more burn specific research into modalities for burn pain control as well as research on multimodal pain control.

Management of exposed pacemaker caused by burns.

Annual implants of cardiovascular implantable devices (CIEDs) are increasing, thus increasing the risk of device exposure. This case presents CIED management issues following traumatic thermal injury. A 59-year-old female presented to intensive care with 42% total body surface area burn involving tissue over her pacemaker generator. Electrophysiologists interrogated and reprogrammed the pacer and observed the patient over 72 hours without pacing. Serratia bacteremia developed and cardiology recommended device removal. The pacemaker generator and leads were removed by cardiothoracic and burn surgery. Postoperatively, asystole required emergency transvenous pacing wire placement. During bacteremia treatment, cardiology planned to pace with an active-fixation screw-in lead with long-term plans to place a single right ventricular chamber leadless pacemaker because of the extensive burns. The patient developed fungemia and the family opted for comfort care. This case report discusses the management of a CIED exposed after a traumatic thermal burn, including device extraction.

Dominant mutants of the Saccharomyces cerevisiae ASF1 histone chaperone bypass the need for CAF-1 in transcriptional silencing by altering histone and Sir protein recruitment.

Transcriptional silencing involves the formation of specialized repressive chromatin structures. Previous studies have shown that the histone H3-H4 chaperone known as chromatin assembly factor 1 (CAF-1) contributes to transcriptional silencing in yeast, although the molecular basis for this was unknown. In this work we have identified mutations in the nonconserved C terminus of antisilencing function 1 (Asf1) that result in enhanced silencing of HMR and telomere-proximal reporters, overcoming the requirement for CAF-1 in transcriptional silencing. We show that CAF-1 mutants have a drastic reduction in DNA-bound histone H3 levels, resulting in reduced recruitment of Sir2 and Sir4 to the silent loci. C-terminal mutants of another histone H3-H4 chaperone Asf1 restore the H3 levels and Sir protein recruitment to the silent loci in CAF-1 mutants, probably as a consequence of the weakened interaction between these Asf1 mutants and histone H3. As such, these studies have identified the nature of the molecular defect in the silent chromatin structure that results from inactivation of the histone chaperone CAF-1.

Role of parathyroid hormone in the mechanosensitivity of fracture healing.

The mechanical environment at a fracture site can influence the course of healing. Intermittent parathyroid hormone (PTH) has been shown to accelerate fracture healing. Intact bone models show that mechanical loading and PTH have a synergistic beneficial effect on osteogenesis. We hypothesized that PTH and mechanical loading would have a similar synergistic effect on fracture healing. Eighty mice underwent surgical osteotomy and intramedullary nailing of the tibia. The mice were divided into four groups: one underwent daily loading, one received daily subcutaneous PTH injections (30 microg/kg/day), one received both loading and PTH, and a control group received sham loading and vehicle injection. Daily loading was applied to the ends of the tibia with an external loading device for 2 weeks. Fracture healing was assessed by microcomputed tomography, histology, and biomechanical testing. The group with both loading and PTH had increased osteoblast and osteoclast activity and was the only group with a significantly larger callus mineral density and bone volume fraction. The PTH only group had significantly more osteoid in the callus compared to the control group, indicating enhanced early osteoblast activity. This group also had a significantly higher bone mineral content and total bone volume compared to controls. The group that received loading as the only intervention had significantly greater osteoclast activity versus controls. The contribution of loading and PTH administration to the fracture healing cascade indicates a synergistic effect. This finding may be of potential clinical utility when weight bearing is utilized to stimulate lower extremity fracture healing.