Structural and spectroscopic characterization of RufO indicates a new biological role in rufomycin biosynthesis.

Rufomycins constitute a class of cyclic heptapeptides isolated from actinomycetes. They are secondary metabolites that show promising treatment against Mycobacterium tuberculosis infections by inhibiting a novel drug target. Several nonproteinogenic amino acids are integrated into rufomycins, including a conserved 3-nitro-tyrosine. RufO, a cytochrome P450 (CYP)-like enzyme, was proposed to catalyze the formation of 3-nitro-tyrosine in the presence of O2 and NO. To define its biological function, the interaction between RufO and the proposed substrate tyrosine is investigated using various spectroscopic methods that are sensitive to the structural change of a heme center. However, a low- to high-spin state transition and a dramatic increase in the redox potential that are commonly found in CYPs upon ligand binding have not been observed. Furthermore, a 1.89-Å crystal structure of RufO shows that the enzyme has flexible surface regions, a wide-open substrate access tunnel, and the heme center is largely exposed to solvent. Comparison with a closely related nitrating CYP reveals a spacious and hydrophobic distal pocket in RufO, which is incapable of stabilizing a free amino acid. Molecular docking validates the experimental data and proposes a possible substrate. Collectively, our results disfavor tyrosine as the substrate of RufO and point to the possibility that the nitration occurs during or after the assembly of the peptides. This study indicates a new function of the unique nitrating enzyme and provides insights into the biosynthesis of nonribosomal peptides.

Test-enhanced learning improves learner attendance during a laparoscopic box trainer simulation program.

BACKGROUND: Laparoscopy is the gold standard approach for many surgical procedures, but it is a complex skill to learn. Laparoscopic simulation training may help, but it is unclear how to best engage trainees in these programs. Test-enhanced learning (TEL) uses regular, well-defined assessments of performance throughout the training phase of learning. AIM: The aim of this study was to assess the effects of TEL on a laparoscopic simulation program involving a cohort of medical student volunteers. MATERIALS AND METHODS: A prospective cohort study was performed with a convenience sample of 40 medical students. Students were recruited to participate in a ten-week laparoscopic simulation program. Twenty students participated in a laparoscopic surgical program with TEL ('TEL group'), and 20 students participated in a standard laparoscopic simulation program ('control group'). RESULTS: Attendance in the TEL group was significantly higher than in the standard group (71 vs 51.5%, P = 0.03). There was no difference between groups in mean time scores. Four themes were identified in qualitative data drawn from student surveys - personal traits and motivators, training context, clear goals and feedback enabling understanding of one's own performance. CONCLUSION: Testing laparoscopic skills throughout a learning program, in conjunction with individualised feedback and tracking of learning trajectory, increases trainee attendance. Laparoscopic simulation training programs are encouraged to reflect on the pedagogic framework in which their procedural skills training operates.

Neurological Complications and Clinical Outcomes of Infective Endocarditis.

OBJECTIVES: The aim of this study is to explore the clinical features associated with neurological complications of infective endocarditis (IE) and to assess the impact of neurological complications on clinical outcomes. MATERIALS AND METHODS: The frequency of relevant clinical features was compared in a case series of IE patients with and without neurological complications admitted to a single health care system from 2015 to 2019. Variables with significant differences (p ≤ 0.05) in baseline characteristics in univariate logistic regression models were entered into multivariable models along with age to determine associations with neurological complications, unfavorable discharge outcomes (modified Rankin score ≥ 3), and in-hospital mortality. RESULTS: 260 patients with a mean age of 51 (±18) years and 103 (40%) females were included. Neurological complications occurred in 165 (63%) patients, with the most common being septic emboli (66 patients, 25%). In the regression analyses, antiplatelet usage (aOR 1.87, 95% CI [1.05-3.32]) and mitral valve vegetations (aOR 2.66, 95% CI [1.22-5.79]) were independently associated with neurological complications. Territorial infarction (aOR 4.13, 95% CI [1.89-9.06]) and encephalopathy (aOR 3.95, 95% CI [1.19-13.05]) were associated with an increased risk of unfavorable outcome, while cardiac surgery was associated with a lower risk of both unfavorable outcome (aOR 0.40, 95% CI [0.22-0.71]) and in-hospital mortality (aOR 0.18, 95% CI [0.09-0.35]). CONCLUSIONS: Neurological complications are common in IE patients and are associated with mitral valve endocarditis and antiplatelet usage. Of the neurological complications, territorial infarcts and encephalopathy are associated with unfavorable discharge outcomes.

Viability assessment and transplantation of extended criteria donor liver grafts using normothermic machine perfusion.

BACKGROUND: The scarcity of available liver grafts necessitates the use of organs from extended criteria donors, a practice associated with an increased risk of graft failure. A notable percentage of deceased donor liver allografts are rejected due to subjective criteria. Normothermic machine perfusion holds promise for introducing objective parameters into this decision-making process. The aim of this study was to compare the outcomes of standard criteria and extended criteria donor allografts after liver transplantation, following viability assessment, using normothermic machine perfusion. METHODS: Liver allografts preserved by normothermic machine perfusion before liver transplantation at the University Hospital of Münster were retrospectively analyzed. Organs were stratified according to the Eurotransplant Donor Risk Index. In total, 101 liver grafts were included in this study and divided into 2 groups: (1) standard criteria donors with a Donor Risk Index <1.8 (DRI-low) and (2) extended criteria donors with a Donor Risk Index ≥1.8 (DRI-high). RESULTS: An increased risk profile of donor livers, as assessed by the Eurotransplant Donor Risk Index, did not correlate with patient or graft survival. High-risk liver grafts were effectively transplanted into recipients with different risk levels after viability assessment by normothermic machine perfusion. However, the recipients' model for end-stage liver disease scores showed a significant association with both overall patient and graft survival. CONCLUSION: The use of normothermic machine perfusion for viability assessment allows safe transplantation of high-risk donor livers and effectively addresses the disparity between donor liver availability and transplantation demand.

Risk factors for neurological complications in left-sided infective endocarditis.

BACKGROUND AND PURPOSE: Neurological complications following infective endocarditis (IE) directly contribute to long-term morbidity. We examined the risk factors for different neurological complications of left-sided IE. METHODS: Using a database of consecutive adults admitted to a health system with left-sided IE from 2015 to 2019, the frequency of cerebral infarcts, intraparenchymal hemorrhage, cerebral microbleeds (CMB), mycotic aneurysm, and encephalopathy was determined. Variables with significant differences comparing each neurological complication (p < 0.1) were entered into regression models along with age to determine predictors. RESULTS: 211 patients with mean age 54 (±18) years, and 69 (33%) females were included. Infarcts were found in 118 (56%) patients, intraparenchymal hemorrhage was found in 17 (8%) patients, CMB were found in 58 (27%) patients, mycotic aneurysms were found in 22 (10%) patients, and encephalopathy occurred in 16 (8%) patients. In multivariable models, vegetation size ≥15 mm was associated with a higher risk of infarcts (aOR 2.26, 95% CI (1.12-4.57)), and the presence of a mycotic aneurysm was a risk factor for intraparenchymal hemorrhage (aOR 18.79, 95% CI (3.97-88.97)). Prosthetic valves (aOR 2.89, 95% CI (1.11-7.54)) and Staphylococcus aureus infection (aOR 3.50, 95% CI (1.08-11.36)) were associated with CMB. No risk factors emerged as predictors of encephalopathy. CONCLUSIONS: Large vegetation size is associated with stroke in patients with IE. Mycotic aneurysms are found at a higher frequency in young patients and are the primary cause of intraparenchymal hemorrhage. CMB may be related to prosthetic valves and Staphylococcus aureus infection.

Screening neuroimaging in neurologically asymptomatic patients with infective endocarditis.

BACKGROUND AND PURPOSE: Neurological complications from infective endocarditis (IE) are common and often present with minimal clinical symptoms. In this study, we examine whether screening neuroimaging in asymptomatic patients results in increased detection of neurological complications and leads to improved patient outcomes. METHODS: Using a database of consecutive adults with IE admitted to a single health system from 2015 to 2019, we selected patients who presented without any neurological symptoms and determined whether these patients underwent screening neuroimaging. The presence of septic emboli, territorial infarcts, intracranial hemorrhage, and mycotic aneurysms was recorded. Variables with significant differences in univariable analyses (p < .1) between those with and without screening neuroimaging were entered into regression models with age and sex to determine predictors of neurological complications and favorable discharge outcomes (modified Rankin score ≤2). RESULTS: A total of 214 patients were included in the study, of which 154 (72%) received screening neuroimaging. Septic emboli were more common in patients who underwent screening imaging (31% vs. 15%, p = 0.02). In the first multivariate analysis, screening neuroimaging was associated with septic emboli (adjusted odds ratio [aOR] = 2.44, 95% confidence interval [CI]: [1.03-5.75], p = 0.04). In the second multivariate analysis, territorial infarcts (aOR = 0.28, 95% CI: [0.11-0.73], p = .01), but not septic emboli (aOR = 0.71, 95% CI: [0.36-1.43], p = 0.34), were associated with a favorable discharge outcome. CONCLUSIONS: Screening neuroimaging leads to the detection of more septic emboli in IE, but only territorial infarcts (in contrast to septic emboli) correlate with an unfavorable discharge outcome.

Incidence of Clostridioides difficile in patients post loop ileostomy reversal in an Australian tertiary hospital: a retrospective study.

INTRODUCTION: The purpose of a loop ileostomy is to temporarily divert faeces away from a distal anastomosis, to reduce the consequences of anastomotic leak. This ultimately requires a second procedure to restore bowel continuity, which confers risk of complications including the development of Clostridioides difficile infection (CDI). It is hypothesized that patients who undergo loop ileostomy reversal are at increased risk of CDI when compared with other patients undergoing elective colorectal surgical procedures, and that these patients also experience an increased length of stay (LOS). METHODS: A retrospective cohort study was performed on all patients who underwent loop ileostomy reversal at the Gold Coast Hospital and Health Service between 1 January 2012 and 31 December 2019. RESULTS: Two hundred and twenty-eight patients were identified. Eight tested positive for CDI on faecal PCR (3.51%), a higher incidence than that in patients who underwent an elective colorectal surgical procedure during the same period (0.83%) (RR = 4.23). Additionally, median LOS for ileostomy reversal patients was significantly increased in those who also had CDI when compared with those without CDI (11 versus 4 days; P = 0.0003). CONCLUSION: The study confirmed that the incidence of CDI was higher in those who underwent ileostomy reversal when compared with an otherwise comparable hospital population (elective colorectal surgery patients). Additionally, those patients who underwent ileostomy reversal and had CDI experienced an increased LOS which translates to increased cost to the healthcare system. Further investigation into pre-operative screening and prophylactic antibiotics should be considered as a measure to mitigate this post-operative complication.

How tufted capuchin monkeys (Sapajus spp.) and humans (Homo sapiens) handle a jointed tool.

The embodied theory of tooling predicts that when using a grasped object as a tool, individuals accommodate their actions to manage the altered degrees of freedom in the body-plus-object system. We tested predictions from this theory by studying how 3 tufted capuchin monkeys (Sapajus spp.) and 6 humans (Homo sapiens) used a hoe to retrieve a token. The hoe's handle was rigid, had 2 segments with 1 planar joint, or had 3 segments with 2 (orthogonal) planar joints. When jointed, rotating the handle could render it rigid. The monkeys used more actions to retrieve the token when the handle had 1 joint than when it had no joints or 2 joints. They did not use exploratory actions frequently nor in a directed manner in any condition. Although they sometimes rotated the handle of the hoe, they did not make it rigid. In a follow-up study, we explored whether humans would rotate the handle to use a 2-jointed hoe in a conventional manner, as predicted both by the embodied theory and theories of functional fixedness in humans. Two people rotated the handle to use the hoe conventionally, but 4 people did not; instead, they used the hoe as it was presented, as did the monkeys. These results confirm some predictions but also highlight shortcomings of the embodied theory with respect to specifying the consequences of adding multiple degrees of freedom. The study of species' perceptual sensitivity to jointed object's inertial properties could help to refine the embodied theory of tooling. (PsycInfo Database Record (c) 2021 APA, all rights reserved).