Abdominal computed tomography scoring systems and experienced radiologists in the radiological diagnosis of small bowel and mesenteric injury.

PURPOSE: Blunt bowel and/or mesenteric injury requiring surgery presents a diagnostic challenge. Although computed tomography (CT) imaging is standard following blunt trauma, findings can be nonspecific. Most studies have focused on the diagnostic value of CT findings in identifying significant bowel and/or mesenteric injury (sBMI). Some studies have described scoring systems to assist with diagnosis. Little attention, has been given to radiologist interpretation of CT scans. This study compared the discriminative ability of scoring systems (BIPS and RAPTOR) with radiologist interpretation in identifying sBMI. METHODS: We conducted a retrospective chart review of trauma patients with suspected sBMI. CT images were reviewed in a blinded fashion to calculate BIPS and RAPTOR scores. Sensitivity and specificity were compared between BIPS, RAPTOR, and the admission CT report with respect to identifying sBMI. RESULTS: One hundred sixty-two patients were identified, 72 (44%) underwent laparotomy and 43 (26.5%) had sBMI. Sensitivity and specificity were: BIPS 49% and 87%, AUC 0.75 (0.67-0.81), P < 0.001; RAPTOR 46% and 82%, AUC 0.72 (0.64-0.79), P < 0.001; radiologist impression 81% and 71%, AUC 0.82(0.75-0.87), P < 0.001. The discriminative ability of the radiologist impression was higher than RAPTOR (P = 0.04) but not BIPS (P = 0.13). There was not a difference between RAPTOR vs. BIPS (P = 0.55). CONCLUSION: Radiologist interpretation of the admission CT scan was discriminative of sBMI. Although surgical vigilance, including evaluation of the CT images and patient, remains fundamental to early diagnosis, the radiologist's impression of the CT scan can be used in clinical practice to simplify the approach to patients with abdominal trauma.

Donor-Acceptor Pyridinium Salts for Photo-Induced Electron-Transfer-Driven Modification of Tryptophan in Peptides, Proteins, and Proteomes Using Visible Light.

Tryptophan (Trp) plays a variety of critical functional roles in protein biochemistry; however, owing to its low natural frequency and poor nucleophilicity, the design of effective methods for both single protein bioconjugation at Trp as well as for in situ chemoproteomic profiling remains a challenge. Here, we report a method for covalent Trp modification that is suitable for both scenarios by invoking photo-induced electron transfer (PET) as a means of driving efficient reactivity. We have engineered biaryl N-carbamoyl pyridinium salts that possess a donor-acceptor relationship that enables optical triggering with visible light whilst simultaneously attenuating the probe's photo-oxidation potential in order to prevent photodegradation. This probe was assayed against a small bank of eight peptides and proteins, where it was found that micromolar concentrations of the probe and short irradiation times (10-60 min) with violet light enabled efficient reactivity toward surface exposed Trp residues. The carbamate transferring group can be used to transfer useful functional groups to proteins including affinity tags and click handles. DFT calculations and other mechanistic analyses reveal correlations between excited state lifetimes, relative fluorescence quantum yields, and chemical reactivity. Biotinylated and azide-functionalized pyridinium salts were used for Trp profiling in HEK293T lysates and in situ in HEK293T cells using 440 nm LED irradiation. Peptide-level enrichment from live cell labeling experiments identified 290 Trp modifications, with 82% selectivity for Trp modification over other π-amino acids, demonstrating the ability of this method to identify and quantify reactive Trp residues from live cells.

In for a Penny, in for a Pound: Obesity weighs heavily on both cost and outcome in trauma.

BACKGROUND: The current literature offers mixed conclusions regarding the effect of increased body mass index (BMI) on outcomes after trauma laparotomy. This study evaluated the impact of obesity on outcomes and cost for patients undergoing trauma laparotomy at a level 1 trauma center. STUDY DESIGN: Data on patients requiring trauma laparotomy in 2016 were prospectively collected and patients were stratified by BMI. Statistical analyses were used to determine variables significantly associated with patient morbidity and length of stay. RESULTS: 313 patients underwent trauma laparotomy: 225 non-obese, 69 obese, and 19 morbidly obese. Obese and morbidly obese patients had longer ICU and hospital lengths of stay (LOS), more ventilator days, larger hospital costs, and higher morbidity compared to non-obese patients. Obesity was an independent predictor for patient morbidity, ICU, and hospital LOS. CONCLUSIONS: Morbidity and length of stay increased with worsening obesity after trauma laparotomy, contributing to rising hospital costs.

Serial CT for Nonoperatively Managed Splenic Injuries.

INTRODUCTION: The role of serial computed tomography (CT) in the nonoperative management of blunt splenic injuries (NOMSIs) remains unclear. The purpose of the study was to determine the utility of serial CT of Grade 2-5 NOMSI in the modern era. METHODS: Blunt splenic injuries were identified over a 3.5-year period, ending in 6/2020. Our institutional protocol for NOMSI mandates a repeat 24-hour CT for Grade 2-5 injuries. Patients age<18, Grade 1 injuries and patients that underwent intervention prior to repeat scan were excluded. Demographics, comorbidities, timing of events (admission, CTs, splenectomy, and angiography), injury details, procedural details, total transfusion requirements, complications, length of stay, mortality, and discharge disposition were recorded. Descriptive statistics were performed. RESULTS: 219 patients with Grade 2-5 NOMSI had both an initial and 24-hour CT after exclusions. 24-hour CT identified 14 patients with new PSA(s) and 11 (5%) went to angiography within 24 hours with 9 (4%) undergoing angioembolization and 4 (2%) had splenectomy. Two hundred and four (93%) had no intervention though eventually 12 went on to angiography and 6 went for splenectomy. The 24-hour CT rarely altered management in the absence of clinical indication or prior PSA on initial CT with 5 (2%) receiving a therapeutic embolization and 2 (1%) had a nontherapeutic angiogram. No deaths were attributable to splenic injury. CONCLUSIONS: Routine 24-hour CT for NOMSI did not impact management. Clinical status and change in exam may warrant repeat CT in select cases in the setting of a plausible alternate explanation. Prompt angioembolization or splenectomy is more appropriate in clear-cut cases of failed NOMSI.

Trauma patient transport times unchanged despite trauma center proliferation: A 10-year review.

INTRODUCTION: In certain regions of the United States, there has been a dramatic proliferation of trauma centers. The goal of our study was to evaluate transport times during this period of trauma center proliferation. METHODS: Aggregated data summarizing level I trauma center admissions in Arizona between 2009 and 2018 were provided to our institution by the Arizona Department of Health Services. We evaluated patient demographics, transport times, and injury severity for both rural and urban injuries. RESULTS: Data included statistics summarizing 266,605 level I trauma admissions in the state of Arizona. The number of state-designated trauma centers during this time increased from 14 to 47, with level I centers increasing from 8 to 13. Slight decreases in mean Injury Severity Score (rural, 9.4 vs. 8.4; urban, 7.9 vs. 7.0) were observed over this period. Median transport time for cases transported from the injury scene directly to a level I center remained stable in urban areas at 0.9 hours in both 2009 and 2018. In rural areas, transport times for these cases were approximately double but also stable, with median times of 1.8 and 1.9 hours. Transport times for cases requiring interfacility transfer before admission at a level I center increased by 0.3 hours for urban injuries (5.3-5.6 hours) and 0.9 hours for rural injuries (5.6-6.5 hours). CONCLUSION: Despite the threefold increase in the number of state-designated trauma centers, transport time has not decreased in urban or rural areas. This finding highlights the need for regulatory oversight regarding the number and geographic placement of state-designated trauma centers. LEVEL OF EVIDENCE: Care management, level IV, Epidemiological, level III.

Discovery of a Functional Covalent Ligand Targeting an Intrinsically Disordered Cysteine within MYC.

MYC is a major oncogenic transcriptional driver of most human cancers that has remained intractable to direct targeting because much of MYC is intrinsically disordered. Here, we have performed a cysteine-reactive covalent ligand screen to identify compounds that could disrupt the binding of MYC to its DNA consensus sequence in vitro and also impair MYC transcriptional activity in situ in cells. We have identified a covalent ligand, EN4, that targets cysteine 171 of MYC within a predicted intrinsically disordered region of the protein. We show that EN4 directly targets MYC in cells, reduces MYC and MAX thermal stability, inhibits MYC transcriptional activity, downregulates multiple MYC transcriptional targets, and impairs tumorigenesis. We also show initial structure-activity relationships of EN4 and identify compounds that show improved potency. Overall, we identify a unique ligandable site within an intrinsically disordered region of MYC that leads to inhibition of MYC transcriptional activity.

Burden of motorcyclists without helmets in a state without a universal helmet law: a propensity score analysis.

BACKGROUND: Although helmets are associated with reduction in mortality from motorcycle collisions, many states have failed to adopt universal helmet laws for motorcyclists, in part on the grounds that prior research is limited by study design (historical controls) and confounding variables. The goal of this study was to evaluate the association of helmet use in motorcycle collisions with hospital charges and mortality in trauma patients with propensity score analysis in a state without a universal helmet law. METHODS: Motorcycle collision data from the Arizona State Trauma Registry from 2014 to 2017 were propensity score matched by regressing helmet use on patient age, sex, race/ethnicity, alcohol intoxication, illicit drug use, and comorbidities. Linear and logistic regression models were used to evaluate the impact of helmet use. RESULTS: Our sample consisted of 6849 cases, of which 3699 (54.0%) were helmeted and 3150 (46.0%) without helmets. The cohort was 88.1% male with an average age of 40.9±16.0 years. Helmeted patients were less likely to be admitted to the intensive care unit (20.3% vs. 23.7%, OR 0.82 (0.72-0.93)) and ventilated (7.8% vs. 12.0%, OR 0.62 (0.52-0.75)). Propensity-matched analyses consisted of 2541 pairs and demonstrated helmet use to be associated with an 8% decrease in hospital charges (B -0.075 (0.034)) and a 56% decrease in mortality (OR 0.44 (0.31-0.58)). DISCUSSION: In a state without mandated helmet use for all motorcyclists, the burden of the unhelmeted rider is significant with respect to lives lost and healthcare charges incurred. Although the helmet law debate with respect to civil liberties is complex and unsettled, it appears clear that helmet use is strongly associated with both survival and less economic encumbrance on the state. LEVEL OF EVIDENCE: Level III, prognostic and epidemiological.

Manumycin polyketides act as molecular glues between UBR7 and P53.

Molecular glues are an intriguing therapeutic modality that harness small molecules to induce interactions between proteins that typically do not interact. However, such molecules are rare and have been discovered fortuitously, thus limiting their potential as a general strategy for therapeutic intervention. We postulated that natural products bearing one or more electrophilic sites may be an unexplored source of new molecular glues, potentially acting through multicovalent attachment. Using chemoproteomic platforms, we show that members of the manumycin family of polyketides, which bear multiple potentially reactive sites, target C374 of the putative E3 ligase UBR7 in breast cancer cells, and engage in molecular glue interactions with the neosubstrate tumor-suppressor TP53, leading to p53 transcriptional activation and cell death. Our results reveal an anticancer mechanism of this natural product family, and highlight the potential for combining chemoproteomics and multicovalent natural products for the discovery of new molecular glues.

The health literacy of hospitalized trauma patients: We should be screening for deficiencies.

BACKGROUND: Although the impact of health literacy (HL) on trauma patient outcomes remains unclear, recent studies have demonstrated that trauma patients with deficient HL have poor understanding of their injuries, are less likely to comply with follow-up, and are relatively less satisfied with physician communication. In this study, we sought to determine if HL deficiency was associated with comprehension of discharge instructions. METHODS: In this prospective study, hospitalized trauma patients underwent evaluation of HL prior to discharge. Newest Vital Sign (NVS) instrument was used to score HL as deficient, marginal, or proficient. Three days postdischarge, patients were telephonically administered a six-point scored questionnaire regarding comprehension of discharge instructions. A general linear model was used to determine the association between HL and comprehension of discharge instructions. RESULTS: Sixty-three patients were administered both NVS and discharge instruction questionnaire. Ten (15.9%) patients scored as deficient in HL on the NVS screen, 16 (25.4%) as marginally proficient, and 37 (58.7%) as proficient. The HL proficiency significantly predicted follow-up score with increasing proficiency associated with higher scores on the discharge comprehension assessment (p < 0.001). Adjusted mean scores (± SE) for deficient, marginal, and proficient patients were 2.8 ± 0.5, 3.2 ± 0.4, and 4.7 ± 0.2. Post hoc comparisons demonstrated significant differences between proficient with marginal proficiency (p = 0.002) and deficient proficiency (p = 0.001). CONCLUSION: Performance on bedside test of HL among trauma inpatients predicted ability to comprehend instructions following hospital discharge. This study supports the value of HL screening prior to discharge. The HL-deficient patients may benefit from a transitional care program to improve comprehension of discharge instructions after leaving the hospital. LEVEL OF EVIDENCE: Therapeutic/Care Management, level III.

Harnessing the anti-cancer natural product nimbolide for targeted protein degradation.

Nimbolide, a terpenoid natural product derived from the Neem tree, impairs cancer pathogenicity; however, the direct targets and mechanisms by which nimbolide exerts its effects are poorly understood. Here, we used activity-based protein profiling (ABPP) chemoproteomic platforms to discover that nimbolide reacts with a novel functional cysteine crucial for substrate recognition in the E3 ubiquitin ligase RNF114. Nimbolide impairs breast cancer cell proliferation in-part by disrupting RNF114-substrate recognition, leading to inhibition of ubiquitination and degradation of tumor suppressors such as p21, resulting in their rapid stabilization. We further demonstrate that nimbolide can be harnessed to recruit RNF114 as an E3 ligase in targeted protein degradation applications and show that synthetically simpler scaffolds are also capable of accessing this unique reactive site. Our study highlights the use of ABPP platforms in uncovering unique druggable modalities accessed by natural products for cancer therapy and targeted protein degradation applications.

Next-generation characterization of the Cancer Cell Line Encyclopedia.

Large panels of comprehensively characterized human cancer models, including the Cancer Cell Line Encyclopedia (CCLE), have provided a rigorous framework with which to study genetic variants, candidate targets, and small-molecule and biological therapeutics and to identify new marker-driven cancer dependencies. To improve our understanding of the molecular features that contribute to cancer phenotypes, including drug responses, here we have expanded the characterizations of cancer cell lines to include genetic, RNA splicing, DNA methylation, histone H3 modification, microRNA expression and reverse-phase protein array data for 1,072 cell lines from individuals of various lineages and ethnicities. Integration of these data with functional characterizations such as drug-sensitivity, short hairpin RNA knockdown and CRISPR-Cas9 knockout data reveals potential targets for cancer drugs and associated biomarkers. Together, this dataset and an accompanying public data portal provide a resource for the acceleration of cancer research using model cancer cell lines.

Pneumomediastinum in blunt trauma: If aerodigestive injury is not seen on CT, invasive workup is not indicated.

BACKGROUND: Pneumomediastinum following blunt trauma is often observed on CT imaging, and concern for associated aerodigestive injury often prompts endoscopy and/or fluoroscopy. In recent years, adoption of multi-detector CT technology has resulted in high resolution images that may clearly identify aerodigestive injuries. The purpose of this study was to evaluate the utility of multi-detector CT in the identification of blunt aerodigestive injuries. METHODS: Over five years, patients with pneumomediastinum following blunt trauma were identified from the registry of a level 1 trauma center. All CT imaging of trauma patients during this time period was accomplished with 64-slice scanners. RESULTS: 127 patients with blunt traumatic pneumomediastinum were identified. Five airway injuries were identified, and all injuries were evident on CT imaging. No patient was found to have airway injury by endoscopy that was not evident on CT. No patient had an esophageal injury. CONCLUSION: Multi-detector CT imaging identifies aerodigestive injuries associated with pneumomediastinum following blunt trauma. The absence of a recognizable aerodigestive injury by CT effectively rules out the presence of such injury.

AAV-Mediated TAZ Gene Replacement Restores Mitochondrial and Cardioskeletal Function in Barth Syndrome.

Barth syndrome (BTHS) is a rare mitochondrial disease that affects heart and skeletal muscle and has no curative treatment. It is caused by recessive mutations in the X-linked gene TAZ, which encodes tafazzin. To develop a clinically relevant gene therapy to restore tafazzin function and treat BTHS, three different adeno-associated virus serotype 9 vectors were tested and compared to identify the optimal promoter-cytomegalovirus (CMV), desmin (Des), or a native tafazzin promoter (Taz)-for TAZ expression following intravenous administration of 1 × 1013 vector genomes/kilogram to a mouse model of BTHS as either neonates (1-2 days of age) or adults (3 months of age). At 5 months of age, evaluations of biodistribution and TAZ expression levels, mouse activity assessments, fatigue in response to exercise, muscle strength, cardiac function, mitochondrial structure, oxygen consumption, and electron transport chain complex activity assays were performed to measure the extent of improvement in treated mice. Each promoter was scored for significant improvement over untreated control mice and significant improvement compared with the other two promoters for every measurement and within each age of administration. All three of the promoters resulted in significant improvements in a majority of the assessments compared with untreated BTHS controls. When scored for overall effectiveness as a gene therapy, the Des promoter was found to provide improvement in the most assessments, followed by the CMV promoter, and finally Taz regardless of injection age. This study provides substantial support for translation of an adeno-associated virus serotype 9-mediated TAZ gene replacement strategy using a Des promoter for human BTHS patients in the clinic.

Tumor-derived IFN triggers chronic pathway agonism and sensitivity to ADAR loss.

Interferons (IFNs) are cytokines that play a critical role in limiting infectious and malignant diseases 1-4 . Emerging data suggest that the strength and duration of IFN signaling can differentially impact cancer therapies, including immune checkpoint blockade 5-7 . Here, we characterize the output of IFN signaling, specifically IFN-stimulated gene (ISG) signatures, in primary tumors from The Cancer Genome Atlas. While immune infiltration correlates with the ISG signature in some primary tumors, the existence of ISG signature-positive tumors without evident infiltration of IFN-producing immune cells suggests that cancer cells per se can be a source of IFN production. Consistent with this hypothesis, analysis of patient-derived tumor xenografts propagated in immune-deficient mice shows evidence of ISG-positive tumors that correlates with expression of human type I and III IFNs derived from the cancer cells. Mechanistic studies using cell line models from the Cancer Cell Line Encyclopedia that harbor ISG signatures demonstrate that this is a by-product of a STING-dependent pathway resulting in chronic tumor-derived IFN production. This imposes a transcriptional state on the tumor, poising it to respond to the aberrant accumulation of double-stranded RNA (dsRNA) due to increased sensor levels (MDA5, RIG-I and PKR). By interrogating our functional short-hairpin RNA screen dataset across 398 cancer cell lines, we show that this ISG transcriptional state creates a novel genetic vulnerability. ISG signature-positive cancer cells are sensitive to the loss of ADAR, a dsRNA-editing enzyme that is also an ISG. A genome-wide CRISPR genetic suppressor screen reveals that the entire type I IFN pathway and the dsRNA-activated kinase, PKR, are required for the lethality induced by ADAR depletion. Therefore, tumor-derived IFN resulting in chronic signaling creates a cellular state primed to respond to dsRNA accumulation, rendering ISG-positive tumors susceptible to ADAR loss.

Correction of copy number induced false positives in CRISPR screens.

Cell autonomous cancer dependencies are now routinely identified using CRISPR loss-of-function viability screens. However, a bias exists that makes it difficult to assess the true essentiality of genes located in amplicons, since the entire amplified region can exhibit lethal scores. These false-positive hits can either be discarded from further analysis, which in cancer models can represent a significant number of hits, or methods can be developed to rescue the true-positives within amplified regions. We propose two methods to rescue true positive hits in amplified regions by correcting for this copy number artefact. The Local Drop Out (LDO) method uses the relative lethality scores within genomic regions to assess true essentiality and does not require additional orthogonal data (e.g. copy number value). LDO is meant to be used in screens covering a dense region of the genome (e.g. a whole chromosome or the whole genome). The General Additive Model (GAM) method models the screening data as a function of the known copy number values and removes the systematic effect from the measured lethality. GAM does not require the same density as LDO, but does require prior knowledge of the copy number values. Both methods have been developed with single sample experiments in mind so that the correction can be applied even in smaller screens. Here we demonstrate the efficacy of both methods at removing the copy number effect and rescuing hits from some of the amplified regions. We estimate a 70-80% decrease of false positive hits with either method in regions of high copy number compared to no correction.

CRISPR Screens Provide a Comprehensive Assessment of Cancer Vulnerabilities but Generate False-Positive Hits for Highly Amplified Genomic Regions.

UNLABELLED: CRISPR/Cas9 has emerged as a powerful new tool to systematically probe gene function. We compared the performance of CRISPR to RNAi-based loss-of-function screens for the identification of cancer dependencies across multiple cancer cell lines. CRISPR dropout screens consistently identified more lethal genes than RNAi, implying that the identification of many cellular dependencies may require full gene inactivation. However, in two aneuploid cancer models, we found that all genes within highly amplified regions, including nonexpressed genes, scored as lethal by CRISPR, revealing an unanticipated class of false-positive hits. In addition, using a CRISPR tiling screen, we found that sgRNAs targeting essential domains generate the strongest lethality phenotypes and thus provide a strategy to rapidly define the protein domains required for cancer dependence. Collectively, these findings not only demonstrate the utility of CRISPR screens in the identification of cancer-essential genes, but also reveal the need to carefully control for false-positive results in chromosomally unstable cancer lines. SIGNIFICANCE: We show in this study that CRISPR-based screens have a significantly lower false-negative rate compared with RNAi-based screens, but have specific liabilities particularly in the interrogation of regions of genome amplification. Therefore, this study provides critical insights for applying CRISPR-based screens toward the systematic identification of new cancer targets. Cancer Discov; 6(8); 900-13. ©2016 AACR.See related commentary by Sheel and Xue, p. 824See related article by Aguirre et al., p. 914This article is highlighted in the In This Issue feature, p. 803.

Characteristics of contralateral carcinomas in patients with differentiated thyroid cancer larger than 1 cm.

PURPOSE: Traditionally, total thyroidectomy has been advocated for patients with tumors larger than 1 cm. However, according to the ATA and NCCN guidelines (2015, USA), patients with tumors up to 4 cm are now eligible for lobectomy. A rationale for adhering to total thyroidectomy might be the presence of contralateral carcinomas. The purpose of this study was to describe the characteristics of contralateral carcinomas in patients with differentiated thyroid cancer (DTC) larger than 1 cm. METHODS: A retrospective study was performed including patients from 17 centers in 5 countries. Adults diagnosed with DTC stage T1b-T3 N0-1a M0 who all underwent a total thyroidectomy were included. The primary endpoint was the presence of a contralateral carcinoma. RESULTS: A total of 1313 patients were included, of whom 426 (32 %) had a contralateral carcinoma. The contralateral carcinomas consisted of 288 (67 %) papillary thyroid carcinomas (PTC), 124 (30 %) follicular variant of a papillary thyroid carcinoma (FvPTC), 5 (1 %) follicular thyroid carcinomas (FTC), and 3 (1 %) Hürthle cell carcinomas (HTC). Ipsilateral multifocality was strongly associated with the presence of contralateral carcinomas (OR 2.62). Of all contralateral carcinomas, 82 % were ≤10 mm and of those 99 % were PTC or FvPTC. Even if the primary tumor was a FTC or HTC, the contralateral carcinoma was (Fv)PTC in 92 % of cases. CONCLUSIONS: This international multicenter study performed on patients with DTC larger than 1 cm shows that contralateral carcinomas occur in one third of patients and, independently of primary tumor subtype, predominantly consist of microPTC.

Low Dose Iron Treatments Induce a DNA Damage Response in Human Endothelial Cells within Minutes.

BACKGROUND: Spontaneous reports from patients able to report vascular sequelae in real time, and recognition that serum non transferrin bound iron may reach or exceed 10µmol/L in the blood stream after iron tablets or infusions, led us to hypothesize that conventional iron treatments may provoke acute vascular injury. This prompted us to examine whether a phenotype could be observed in normal human endothelial cells treated with low dose iron. METHODOLOGY: Confluent primary human endothelial cells (EC) were treated with filter-sterilized iron (II) citrate or fresh media for RNA sequencing and validation studies. RNA transcript profiles were evaluated using directional RNA sequencing with no pre-specification of target sequences. Alignments were counted for exons and junctions of the gene strand only, blinded to treatment types. PRINCIPAL FINDINGS: Rapid changes in RNA transcript profiles were observed in endothelial cells treated with 10µmol/L iron (II) citrate, compared to media-treated cells. Clustering for Gene Ontology (GO) performed on all differentially expressed genes revealed significant differences in biological process terms between iron and media-treated EC, whereas 10 sets of an equivalent number of randomly selected genes from the respective EC gene datasets showed no significant differences in any GO terms. After 1 hour, differentially expressed genes clustered to vesicle mediated transport, protein catabolism, and cell cycle (Benjamini p = 0.0016, 0.0024 and 0.0032 respectively), and by 6 hours, to cellular response to DNA damage stimulus most significantly through DNA repair genes FANCG, BLM, and H2AFX. Comet assays demonstrated that 10µM iron treatment elicited DNA damage within 1 hour. This was accompanied by a brisk DNA damage response pulse, as ascertained by the development of DNA damage response (DDR) foci, and p53 stabilization. SIGNIFICANCE: These data suggest that low dose iron treatments are sufficient to modify the vascular endothelium, and induce a DNA damage response.

The change in energy absorbed post removal of metalwork in a simulated paediatric long bone fracture.

PURPOSE: The surgical treatment of paediatric fractures is increasing. Open reduction and internal fixation (ORIF) with plates and screws is long established, whilst the use of elastic stable intramedullary nailing (ESIN) has become increasingly popular. This study quantifies, in terms of the energy required to produce a fracture, the biomechanical sequelae of both techniques post removal of metalwork, to provide clinicians with evidence to guide post-operative advice. METHODS: An immature bovine model was adopted to ascertain whether these techniques exposed the bone to a greater re-fracture risk following removal of the device. Bones were prepared to reflect ORIF or ESIN techniques, or prepared intact for the acquisition of control data. Each bone was tested to failure at 90 °/s, with the absorbed energy then being calculated to determine the relative difference between each technique and versus control data. Data describing peak shear stress and torque were recorded. RESULTS: Absorbed energy was reduced by 47 % in the ORIF group compared to both the control (p = 0.011) and ESIN (p = 0.018) groups. The peak shear stress and torque were also significantly different. All ORIF bones failed through drill holes, suggesting stress localisation around the defects. CONCLUSION: This study suggests that there is a significantly higher re-fracture risk following the removal of ORIF plates when compared to both ESIN and the control environment. Whilst this may reflect the intuitive view of many clinicians, this study provides a quantitative value of the reduction in strength and should help clinicians to appropriately caution patients and parents prior to surgery.