Cumulative radiation in critically ill patients: a retrospective audit of ionising radiation exposure in an intensive care unit.

OBJECTIVE: Ionising radiation is a valuable tool in modern medicine including for patients in an intensive care unit (ICU). However, clinicians are faced with a trade-off between benefit of information received from procedure versus risks associated with radiation. As a first step to understanding the risk and benefits of radiation exposure to ICU patients, we aimed to assess the cumulative levels of ionising radiation patients receive during their ICU stay. DESIGN: Retrospective audit. SETTING: A single tertiary care ICU in South Australia. PARTICIPANTS: This audit included 526 patients admitted to the ICU at Flinders Medical Centre, Adelaide, SA, for longer than 120 hours (long stay) over a 12-month period from April 2015 to April 2016. MAIN OUTCOME MEASURES: Cumulative radiation exposure to ICU patients. RESULTS: The 526 patients audited underwent 4331 procedures totalling 5688.45 mSv of ionising radiation. The most frequent procedure was chest x-ray (82%), which contributed 1.2% to cumulative effective dose (CED). Although only 3.6% of the total procedures, abdominal and pelvic computed tomography (CT) contributed the most to CED (68%). Over 50% of patients received less than 1 mSv CED during their stay in the ICU. However, 6% received > 50 mSv and 1.3% received > 100 mSv CED. Trauma patients received significantly higher CED compared with other admission diagnoses, and CED increased with length of stay. CONCLUSION: Most ICU patients received low CED during their stay, with the majority receiving less than the recommended limit for members of the public (1 mSv). These results may educate clinicians regarding radiation exposures in ICU settings, highlighting the relatively low exposures and thus low risk to the patients.

Acute pulmonary and splenic response in an in vivo model of whole-body low-dose X-radiation exposure.

Purpose: Diagnostic radiation is an important part of patient care in the Intensive Care Unit; however, there is little data on the acute effects of exposure to these doses. We investigated pulmonary and splenic response 30 minutes, 4 hours or 24 hours after exposure to 2 mGy, 20 mGy, 200 mGy or 4 Gy whole-body X-radiation in a Sprague Dawley rat model. Materials and methods: Lung injury was assessed via respiratory mechanics, pulmonary edema, cellular, and proteinaceous fluid infiltrate and protein expression of oxidative stress markers. The radiation effect on the spleen was determined via proliferation, apoptosis and protein expression of oxidative stress markers. Results: All measurements of the lung did not differ from sham animals except for an increase in catalase after high dose exposure. Stimulated splenocyte proliferation increased after sham and low dose exposure, did not change after 200 mGy exposure and was significantly lower after 4 Gy exposure. The number of apoptotic cells increased 4 hours after 4 Gy exposure. There were fewer apoptotic cells after low dose exposure compared to sham. Both catalase and MnSOD were increased after 4 Gy exposure. Conclusion: There was no measured effect on pulmonary function while there was an impact to the spleen after low and high dose exposure.

Titanium Kirschner Wires Resist Biofilms Better Than Stainless Steel and Hydroxyapatite-coated Wires: An In Vitro Study.

AIM: External fixation surgery is frequently complicated by percutaneous pin site infection focused on the surface of the fixator pin. The primary aim of this study was to compare biofilm growth of clinically isolated pin site bacteria on Kirschner wires of different materials. MATERIALS AND METHODS: Two commonly infecting species, Staphylococcus epidermidis and Proteus mirabilis, were isolated from patients' pin sites. A stirred batch bioreactor was used to grow these bacteria as single culture and co-cultured biofilms on Kirschner wires made of three different materials: stainless steel, hydroxyapatite-coated steel and titanium alloy. RESULTS: We found that the surface density of viable cells within these biofilms was 3x higher on stainless steel and 4.5x higher on hydroxyapatite-coated wires than on the titanium wires. CONCLUSION: Our results suggest that the lower rates of clinical pin site infection seen with titanium Kirschner wires are due to, at least in part, titanium's better bacterial biofilm resistance. CLINICAL SIGNIFICANCE: Our results are consistent with clinical studies which have found that pin site infection rates are reduced by the use of titanium relative to stainless steel or hydroxyapatite-coated pins. HOW TO CITE THIS ARTICLE: McEvoy JP, Martin P, Khaleel A, et al. Titanium Kirschner Wires Resist Biofilms Better Than Stainless Steel and Hydroxyapatite-coated Wires: An In Vitro Study. Strategies Trauma Limb Reconstr 2019;14(2):57-64.

The Effect of Aquaporin 1-Inhibition on Vasculogenic Mimicry in Malignant Mesothelioma.

Malignant mesothelioma (MM) is an aggressive malignancy of the serosal membranes, with poor overall survival and quality of life. Limited targeted treatment strategies exist due to restricted knowledge of pathogenic pathways. Vasculogenic mimicry (VM) is a newly described phenomenon associated with increased aggressiveness in other malignancies, and has been characterized in MM. Normal mesothelium expresses aquaporin 1 (AQP1) and retained expression has been associated with improved survival in MM. AQP1 is expressed by normal vascular endothelium and is involved in mediating MM cell motility and proliferation. We investigated the role of AQP1 in VM, and its interaction with the pro-angiogenic factor vascular endothelial growth factor A (VEGFA), which is variably expressed in MM. Matrigel VM assays were performed using NCI-H226 and NCI-H28 MM cell lines and primary cells in hypoxia and normoxia. The synthetic blocker AqB050 and siRNA were used to inhibit AQP1, and bevacizumab was used to inhibit VEGF. Inhibition of AQP1 resulted in increased VEGFA secretion by MM cells and reduced VM in MM cell lines in hypoxia but not normoxia. No change in VM was seen in MM primary cells. Combined inhibition of AQP1 and VEGF had no effect on VM in normoxia. In a heterotopic xenograft mouse model, AqB050 treatment did not alter vessel formation. AQP1 may interact with VEGFA and play a role in VM, especially under hypoxic conditions, but the heterogeneity of MM cells may result in different dominant pathways between patients.

Vasculogenic mimicry in malignant mesothelioma: an experimental and immunohistochemical analysis.

Vasculogenic mimicry, the process in which cancer cells form angiomatoid structures independent of or in addition to host angiogenesis has been recorded in several otherwise non-endothelial malignant neoplasms. This study describes evidence of routine vascular mimicry by human mesothelioma cell lines in vitro, when the cell lines are cultured alone or co-cultured with human umbilical vascular endothelial cells, with the formation of angiomatoid tubular networks. Vasculogenic mimicry is also supported by immunohistochemical demonstration of human-specific anti-mitochondria antibody labelling of tumour-associated vasculature of human mesothelioma cells xenotransplanted into nude mice, and by evidence of vascular mimicry in some biopsy samples of human malignant mesotheliomas. These studies show mosaic interlacing of cells that co-label or label individually for immunohistochemical markers of endothelial and mesothelial differentiation. If vascular mimicry in mesothelioma can be characterised more fully, this may facilitate identification of more specific and targeted therapeutic approaches such as anti-angiogenesis in combination with chemotherapy and immunotherapy or other therapeutic approaches.

Redox reactions of the non-heme iron in photosystem II: an EPR spectroscopic study.

Photosystem II (PSII) contains a non-heme ferrous ion, located on the stromal side of the protein in close proximity to quinones A and B (Q(A) and Q(B)). We used EPR spectroscopy to examine the temperature-dependent redox reactions of the iron-quinone site, using it as a probe of potentially physiologically relevant proton-coupled electron-transfer (PCET) reactions. Complete chemical oxidation of the non-heme iron at ambient temperatures was followed by cryogenic photoreduction, producing a temperature-dependent yield of Fe(2+)Q(A) (or Fe(3+)Q(A)(-))...Chl(+)/Car(+)/Y(D)(*) charge separations. These charge separations were subsequently observed to partially recombine in the dark at cryogenic temperatures. We observed no double photochemical charge separations upon illumination at temperatures