Molecular basis for substrate recognition and septum cleavage by AtlA, the major N-acetylglucosaminidase of Enterococcus faecalis.

The cleavage of septal peptidoglycan at the end of cell division facilitates the separation of the two daughter cells. The hydrolases involved in this process (called autolysins) are potentially lethal enzymes that can cause cell death; their activity, therefore, must be tightly controlled during cell growth. In Enterococcus faecalis, the N-acetylglucosaminidase AtlA plays a predominant role in cell separation. atlA mutants form long cell chains and are significantly less virulent in the zebrafish model of infection. The attenuated virulence of atlA mutants is underpinned by a limited dissemination of bacterial chains in the host organism and a more efficient uptake by phagocytes that clear the infection. AtlA has structural homologs in other important pathogens, such as Listeria monocytogenes and Salmonella typhimurium, and therefore represents an attractive model to design new inhibitors of bacterial pathogenesis. Here, we provide a 1.45 Å crystal structure of the E. faecalis AtlA catalytic domain that reveals a closed conformation of a conserved ß-hairpin and a complex network of hydrogen bonds that bring two catalytic residues to the ideal distance for an inverting mechanism. Based on the model of the AtlA-substrate complex, we identify key residues critical for substrate recognition and septum cleavage during bacterial growth. We propose that this work will provide useful information for the rational design of specific inhibitors targeting this enterococcal virulence factor and its orthologs in other pathogens.

Repertoire analysis of γδ T cells in the chicken enables functional annotation of the genomic region revealing highly variable pan-tissue TCR gamma V gene usage as well as identifying public and private repertoires.

BACKGROUND: Despite increasing interest in γδ T cells and their non-classical behaviour, most studies focus on animals with low numbers of circulating γδ T cells, such as mice and humans. Arguably, γδ T cell functions might be more prominent in chickens where these cells form a higher proportion of the circulatory T cell compartment. The TCR repertoire defines different subsets of γδ T cells, and such analysis is facilitated by well-annotated TCR loci. γδ T cells are considered at the cusp of innate and adaptive immunity but most functions have been identified in γδ low species. A deeper understanding of TCR repertoire biology in γδ high and γδ low animals is critical for defining the evolution of the function of γδ T cells. Repertoire dynamics will reveal populations that can be classified as innate-like or adaptive-like as well as those that straddle this definition. RESULTS: Here, a recent discrepancy in the structure of the chicken TCR gamma locus is resolved, demonstrating that tandem duplication events have shaped the evolution of this locus. Importantly, repertoire sequencing revealed large differences in the usage of individual TRGV genes, a pattern conserved across multiple tissues, including thymus, spleen and the gut. A single TRGV gene, TRGV3.3, with a highly diverse private CDR3 repertoire dominated every tissue in all birds. TRGV usage patterns were partly explained by the TRGV-associated recombination signal sequences. Public CDR3 clonotypes represented varying proportions of the repertoire of TCRs utilising different TRGVs, with one TRGV dominated by super-public clones present in all birds. CONCLUSIONS: The application of repertoire analysis enabled functional annotation of the TCRG locus in a species with a high circulating γδ phenotype. This revealed variable usage of TCRGV genes across multiple tissues, a pattern quite different to that found in γδ low species (human and mouse). Defining the repertoire biology of avian γδ T cells will be key to understanding the evolution and functional diversity of these enigmatic lymphocytes in an animal that is numerically more reliant on them. Practically, this will reveal novel ways in which these cells can be exploited to improve health in medical and veterinary contexts.

Radiofrequency Ablation for the Palliative Treatment of Bone Metastases: Outcomes from the Multicenter OsteoCool Tumor Ablation Post-Market Study (OPuS One Study) in 100 Patients.

PURPOSE: To evaluate the effectiveness of radiofrequency (RF) ablation as measured by change in worst pain score from baseline to 3 mo after RF ablation for the palliative treatment of painful bone metastases. MATERIALS AND METHODS: One hundred patients (mean age, 64.6 y) underwent RF ablation for metastatic bone disease and were followed up to 6 mo. Subjects' pain and quality of life were measured before RF ablation and postoperatively by using the Brief Pain Index and European Quality of Life questionnaires. Opioid agent use and device-, procedure-, and/or therapy-related adverse events (AEs) were collected. RESULTS: Eighty-seven patients were treated for tumors involving the thoracolumbar spine and 13 for tumors located in the pelvis and/or sacrum. All ablations were technically successful, and 97% were followed by cementoplasty. Mean worst pain score decreased from 8.2 ± 1.7 at baseline to 3.5 ± 3.2 at 6 mo (n = 22; P < 0.0001 for all visits). Subjects experienced significant improvement for all visits in average pain (P < .0001), pain interference (P < .0001), and quality of life (P < .003). Four AEs were reported, of which 2 resulted in hospitalization for pneumonia and respiratory failure. All 30 deaths reported during the study were attributed to the underlying malignancy and not related to the study procedure. CONCLUSIONS: Results from this study show rapid (within 3 d) and statistically significant pain improvement with sustained long-term relief through 6 mo in patients treated with RF ablation for metastatic bone disease.

Comparison of Type II Endoleak Embolizations: Embolization of Endoleak Nidus Only versus Embolization of Endoleak Nidus and Branch Vessels.

PURPOSE: To compare outcomes of type II endoleak embolization involving embolization of the endoleak nidus only vs embolization of the endoleak nidus and branch vessels in patients treated with endovascular repair of abdominal aortic aneurysms. MATERIALS AND METHODS: Twenty-nine consecutive patients (mean age, 77.9 y; range, 63-88 y) with type II endoleak who underwent embolization from 2004 to 2015 were retrospectively reviewed. Patients were divided into 2 groups: embolization of endoleak nidus only (group A) and embolization of endoleak nidus and branch vessels (group B). Mean follow-up intervals were 20.5 months ± 14.7 in group A and 24.3 months ± 18.5 in group B. Outcomes were compared between groups by Mann-Whitney U and Pearson χ2 tests. RESULTS: Mean interval from endovascular aneurysm repair to embolization was 47.6 months ± 42.9, and mean presentation time of endoleak before embolization was 23.1 months ± 25.8. Coils (n = 28) and liquid embolic agents (n = 23) were used for embolization. There were no significant differences in rates of residual endoleak (50% vs 53.8%; P = .96) or sac decrease/stabilization (62.5% vs 61.5%; P = .64). Procedure time and radiation exposure in group B (132.3 min ± 78.1; 232.4 Gy·cm2 ± 130.7) were greater than in group A (63.4 min ± 11.9; 61.5 Gy·cm2 ± 35.5; P < .01). There were no procedure-related complications. CONCLUSIONS: Embolization of the endoleak nidus and branch vessels is not superior to embolization of only the nidus in terms of occlusion of type II endoleak and change in sac size despite requiring longer procedure times and resulting in greater patient radiation exposure.

Incidence and Clinical Significance of Renal Infarct After Fenestrated Endovascular Aortic Aneurysm Repair.

OBJECTIVE: The purpose of this study is to determine the incidence and clinical significance of renal infarcts after fenestrated endovascular aortic aneurysm repair (FEVAR). MATERIALS AND METHODS: All patients who underwent FEVAR with unenhanced and contrast-enhanced CT angiography during a 4-year period were retrospectively reviewed. Two staff radiologists reviewed pre- and post-FEVAR CT examinations for the presence of renal infarcts. Pre- and postoperative serum creatinine levels were examined to determine statistical significance. The incidence of renal infarct and percentage of renal volume reduction were calculated. RESULTS: Ninety patients were included for analysis. All patients had a mild progressive increase in serum creatinine level after FEVAR. Twenty-three patients (26%) had a renal infarct identified on post-FEVAR CT, nine (39%) of which were secondary to intentional exclusion of an accessory renal artery and 14 (61%) of which were presumed to be embolic. Two patients with presumed embolic infarcts and three with exclusion of an accessory renal artery had an increase in serum creatinine level of greater than 0.3 mg/dL at 1 month after FEVAR. CONCLUSION: Although renal infarcts are common after FEVAR, the clinical relevance of these events appears to be limited, with less than one-quarter of patients with renal infarcts experiencing a decline in renal function.

Radiation dose associated with CT-guided drain placement for pediatric patients.

BACKGROUND: To date, there are limited radiation dose data on CT-guided procedures in pediatric patients. OBJECTIVE: Our goal was to quantify the radiation dose associated with pediatric CT-guided drain placement and follow-up drain evaluations in order to estimate effective dose. MATERIALS AND METHODS: We searched the electronic medical record and picture archiving and communication system (PACS) to identify all pediatric (<18 years old) CT-guided drain placements performed between January 2008 and December 2013 at our institution. We compiled patient data and radiation dose information from CT-guided drain placements as well as pre-procedural diagnostic CTs and post-procedural follow-up fluoroscopic abscess catheter injections (sinograms). Then we converted dose-length product, fluoroscopy time and number of acquisitions to effective doses using Monte Carlo simulations and age-appropriate conversion factors based on annual quality-control testing. RESULTS: Fifty-two drainages were identified with mean patient age of 11.0 years (5 weeks to 17 years). Most children had diagnoses of appendicitis (n=23) or inflammatory bowel disease (n=11). Forty-seven patients had diagnostic CTs, with a mean effective dose of 7.3 mSv (range 1.1-25.5 mSv). Drains remained in place for an average of 16.9 days (range 0-75 days), with an average of 0.9 (0-5) sinograms per patient in follow-up. The mean effective dose for all drainages and follow-up exams was 5.3 mSv (0.7-17.1) and 62% (32/52) of the children had effective doses less than 5 mSv. CONCLUSION: The majority of pediatric patients who have undergone CT-guided drain placements at our institution have received total radiation doses on par with diagnostic ranges. This information could be useful when describing the dose of radiation to parents and providers when CT-guided drain placement is necessary.

Suitability of the DRI Hydrocodone/Hydromorphone Immunoassay in the Clinical Environment at a Lower Cutoff: Validation With LC-MS/MS Analysis.

BACKGROUND: We evaluated the analytical performance of the DRI hydrocodone/hydromorphone assay by comparing semiquantitative values obtained by this assay with values obtained by a liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method. We also evaluated the possibility of lowering the cutoff of the DRI assay from 300 to 100 ng/mL. METHODS: We compared semiquantitative values obtained by the DRI assay in 97 specimens with values obtained by the LC-MS/MS method including 10 specimens containing hydrocodone and/or hydromorphone concentrations between 105.0 and 145.0 ng/mL (determined by LC-MS/MS) to determine the sensitivity at 100 ng/mL. In addition, several opioids at a concentration of 5000 ng/mL were also analyzed by the DRI assay to determine its specificity. RESULTS: We observed no false-negative result using the DRI immunoassay in 96 specimens that showed semiquantitative values at 100 ng/mL or higher. However, one specimen containing 110 ng/mL of hydrocodone was false negative with the DRI assay (semiquantitative value 88 ng/mL, below 100 ng/mL cutoff). The semiquantitative values produced by DRI showed poor correlation with values determined by the LC-MS/MS method. The sensitivity of the DRI assay at 100 ng/mL was 90%, and the assay was very specific showing minimal cross-reactivity only with oxycodone and oxymorphone. CONCLUSIONS: DRI immunoassay for hydrocodone/hydromorphone is a cost-effective method of screening urine specimens in the clinical environment at a lower cutoff of 100 ng/mL.

Assessing medical students' knowledge of IR at two American medical schools.

PURPOSE: To determine if there was a difference in the level of knowledge about interventional radiology (IR) between medical students in preclinical years of training compared with medical students in clinical years of training at two medical schools and to compare awareness of IR based on the curriculum at each school: one with required radiology education and one without such a requirement. MATERIALS AND METHODS: An anonymous survey was distributed to students at two medical schools; the survey assessed knowledge of IR, knowledge of training pathways, and preferred methods to increase exposure. Responses of the preclinical and clinical groups were compared, and responses from the clinical groups at each school were compared. RESULTS: "Poor" or "fair" knowledge of IR was reported by 84% (n = 217 of 259) of preclinical students compared with 62% of clinical students (n = 110 of 177; P < .001). IR was being considered as a career by 11% of all students (15%, n = 40 of 259 preclinical; 5%, n = 9 of 177 clinical). The main reason respondents were not considering IR was "lack of knowledge" (65%, n = 136 of 210 preclinical; 20%, n = 32 of 162 clinical). Students in the clinical group at the institution with a required radiology rotation reported significantly better knowledge of IR than clinical students from the institution without a required clerkship (P = .017). CONCLUSIONS: There are significant differences in knowledge of IR between preclinical and clinical students. Required radiology education in the clinical years does increase awareness of IR.

Survey of current status and physician opinion regarding ancillary staffing for the IR suite.

PURPOSE: To survey the status quo of ancillary staffing in predominantly hospital-based interventional radiology (IR) suites and to assess interventional radiologist attitudes toward current IR procedure room staffing availability and appropriateness. MATERIALS AND METHODS: Invitations to an online survey composed of 26 questions focused on levels of IR suite ancillary staffing as well as operators' opinions of current IR procedure room staffing were sent via email to 2,284 active Society of Interventional Radiology members. RESULTS: There were 777 survey responses. Nurse staffing count per IR room was at least one in 90% (n = 699) during regular hours and 93.6% (n = 730) during off-hours, respectively. A second technologist was frequently used during regular hours and, to a lesser extent, during on-call hours (n = 341 [43.9%] and n = 122 [15.7%]), respectively. Ten and 15% of IR respondents believe staffing support is inadequate for most interventional procedures requiring moderate sedation during normal business hours and off-hours/weekends, respectively, and 69% and 56% of IR respondents believe anesthesia support is inadequate during normal business hours and during off-hours, respectively. CONCLUSIONS: The number of technologists used per IR suite varies across practices and frequently exceeds that of earlier American College of Radiology recommendations, whereas use of IR suite nurse staffing is consistent with approximately one per suite and constant. However, there is dissatisfaction among surveyed interventional radiologists with availability and appropriateness of staffing of the IR procedure room, particularly during on-call hours and weekends, as well as with anesthesia support for emergent cases. No evidence-based guidelines for staffing the IR suite currently exist. This underscores the need for further investigation with the ultimate goal of creating such guidelines.

Bone microarchitectural alterations associated with spinal cord injury: Relation to sex hormones, metabolic factors, and loading.

CONTEXT: People living with spinal cord injury (SCI) are at high risk for bone fractures. Neural, hormonal and metabolic contributors to bone microarchitectural alterations are incompletely understood. OBJECTIVE: To determine the relationship of physical, metabolic and endocrine characteristics with bone microarchitecture, characterized using high-resolution peripheral quantitative computed tomography (HRpQCT) in SCI. DESIGN: Cross-sectional analyses of bone properties in people with SCI. PARTICIPANTS: Twenty adults with SCI and paraplegia (12) or motor incomplete quadriplegia (8). OUTCOME MEASURES: Distal tibia and radius HRpQCT parameters, including density, microstructure and strength by microfinite element anaysis (µFEA); sex hormones; metabolic and inflammatory markers. RESULTS: The mean age of the participants with SCI was 41.5 ± 10.3 years, BMI 25.7 ± 6.2 kg/m2, time since injury 10.4 ± 9.0 years. Participants with SCI had significantly lower median total (Z score - 3.3), trabecular (-2.93), and cortical vBMD (-1.87), and Failure Load by µFEA (-2.48) at the tibia than controls. However, radius vBMD, aBMD and microarchitecture were similar in participants with SCI and un-injured controls. Unexpectedly, C-Reactive Protein (CRP) was positively associated with tibial trabecular vBMD (ß = 0.77, p = 0.02), thickness (ß = 0.52, p = 0.04) and number (ß = 0.92, p = 0.02). At the radius, estradiol level was positively associated with total vBMD (ß = 0.59, p = 0.01), trabecular thickness (ß = 0.43, p = 0.04), cortical thickness (ß = 0.63, p = 0.01) and cortical porosity (ß = 0.74 p = 0.04). CONCLUSIONS: Radius vBMD and microarchitecture is preserved but tibial total, cortical and trabecular vBMD, and estimated bone strength are markedly lower and bone microarchitectural parameters substantially degraded in people with SCI. The alterations in bone microarchitecture in people with SCI are likely multifactorial, however marked degradation of bone microarchitecture in tibia but not radius suggests that unloading is an important contributor of site-specific alterations of bone microarchitecture after SCI. Fracture prevention in SCI should focus on strategies to safely increase bone loading. CLINICALTRIALS: gov registration #: (NCT03576001).

Building Radiology Equity: Themes from the 2023 RAD-AID Conference on International Radiology and Global Health.

Low- and middle-income countries are significantly impacted by the global scarcity of medical imaging services. Medical imaging is an essential component for diagnosis and guided treatment, which is needed to meet the current challenges of increasing chronic diseases and preparedness for acute-care response. We present some key themes essential for improving global health equity, which were discussed at the 2023 RAD-AID Conference on International Radiology and Global Health. They include (1) capacity building, (2) artificial intelligence, (3) community-based patient navigation, (4) organizational design for multidisciplinary global health strategy, (5) implementation science, and (6) innovation. Although not exhaustive, these themes should be considered influential as we guide and expand global health radiology programs in low- and middle-income countries in the coming years.

Radiation protection in interventional radiology: survey results of attitudes and use.

PURPOSE: To assess attitudes of interventional radiologists toward personal radiation protection and the use of radiation protection devices. MATERIALS AND METHODS: Invitations to an anonymous online survey that comprised eight questions focused on operator attitudes toward radiation protection devices were sent via e-mail to the active membership of the Society of Interventional Radiology (SIR): a total of 3,158 e-mail invitations. A single reminder e-mail was sent. RESULTS: There were 504 survey responders (16% response rate). Reported radiation safety device use included lead apron (99%), thyroid shield (94%), leaded eyeglasses (54%), ceiling-suspended leaded shield (44%), rolling leaded shields (12%), ceiling-suspended/rolling lead-equivalent apron (4%), radiation-attenuating sterile surgical gloves (1%), and sterile lead-equivalent patient-mounted drape (4%). Reasons commonly cited for not using certain devices were comfort (eyewear), ease of use (mounted shields), and lack of availability (rolling/hanging shields and patient-mounted shields). CONCLUSIONS: Interventionalists have an array of tools from which to choose for personal radiation protection; however, for a variety of reasons related to lack of availability or choice, these tools are not universally employed. Further study may be of value to clarify why comfort was cited most often as the primary barrier to the use of protective eyewear and difficulty of use was cited as the primary barrier to use of mounted shields (despite reporting that concern for radiation-induced injury to the eye is paramount). It may also be of interest to further study why certain devices with demonstrable protection effects are not readily available, such as rolling/hanging and patient-mounted shields.

Education resources in remote Australian Indigenous community dog health programs: a comparison of community and extra-community-produced resources.

Commercial dog health programs in Australian Indigenous communities are a relatively recent occurrence. Health promotion for these programs is an even more recent development, and lacks data on effective practices. This paper analyses 38 resources created by veterinary-community partnerships in Indigenous communities, to 71 resources available through local veterinary service providers. On average, community-produced resources used significantly more of the resource area as image, more imagery as communicative rather than decorative images, larger fonts and smaller segments of text and used images of people with a range of skin tones. As well as informal registers of Standard Australian English, community-produced resources used Aboriginal English and/or Creole languages in their text, while extra-community (EC)-produced resources did not. The text of EC resources had Flesh-Kincaid reading grade levels that excluded a large proportion of community recipients. Also, they did not cover some topics of importance in communities, used academic, formal and technical language, and did not depict people of a representative range of skin tones. As such, community-produced resources were more relevant to the unique situations in remote communities, while EC resources were often inappropriate and in some cases could even distance recipients by using inappropriate language, formats and imagery.

Advancing IR in Underserved Regions: Interventional Radiology Simulation Near and Far.

Simulation facilitates learning by imitating real-world systems or processes utilizing educational tools and models. Various fields, including business, aviation, and education use simulation for training. In healthcare, simulation provides trainees opportunities to develop procedural skills in a safe environment, building their understanding through hands-on interactions and experiences rather than passive didactics. Simulation is classified into low, medium, and high fidelity, based on how closely it mimics real-life experience. Its use in education is a valuable adjunct to instructional support and training with multiple potential benefits. Interventional radiology (IR) trainees can build technical and clinical proficiency prior to working directly on a patient. Simulation promotes experiential learning, constructivist learning, and student centeredness, thus giving students control over their learning and knowledge acquisition. More recently, the creative use of remote simulation has augmented traditional virtual didactic lectures, thereby further engaging international learners and enhancing remote collaboration. Despite the challenges to implementation, the addition of simulation in IR education is proving invaluable to supporting trainees and physicians in underserved regions.

Safety and efficacy of direct percutaneous endoscopic jejunostomy placement in patients with previous upper gastrointestinal resection: A retrospective cohort study.

BACKGROUND: Percutaneous jejunal enteral access can be obtained with percutaneous endoscopic gastric jejunostomy (PEGJ) and direct percutaneous endoscopic jejunostomy (DPEJ) tubes. PEGJ may not be feasible in patients with previous gastric resection (PGR) and DPEJ may be the only option. Our aim is to determine if DPEJ tubes can be placed successfully in patients with history of gastrointestinal (GI) surgery and if success rates are comparable to DPEJ or PEGJ in those without prior GI surgery. METHODS: We reviewed all tube placements performed from 2010 to present. Procedures were performed using a pediatric colonoscope. Previous upper GI surgery was defined as PGR or esophagectomy with gastric pull-up. Adverse events (AEs) were graded per American Society for Gastrointestinal Endoscopy criteria. Mild events included unplanned medical consultation or hospitalization <3 days, and moderate events included repeat endoscopy without surgical intervention. RESULTS: Successful placement rates were high regardless of GI surgical history. Patients receiving a DPEJ with a history of GI surgery were significantly less likely to experience an AE compared with those receiving DPEJ with no history and compared with PEGJ patients with or without a history. CONCLUSIONS: DPEJ placement in patients with previous upper GI surgery has very high success rate. It is associated with lower AE rates than patients receiving DPEJ without previous gastric surgery, or PEGJ regardless of previous gastric surgery. Patients with a history of upper GI surgery requiring enteral access may benefit from DPEJ over PEGJ placement considering its very high success rate and lower incidence of AEs.