Alpha power indexes task-related networks on large and small scales: A multimodal ECoG study in humans and a non-human primate.

Performing different tasks, such as generating motor movements or processing sensory input, requires the recruitment of specific networks of neuronal populations. Previous studies suggested that power variations in the alpha band (8-12Hz) may implement such recruitment of task-specific populations by increasing cortical excitability in task-related areas while inhibiting population-level cortical activity in task-unrelated areas (Klimesch et al., 2007; Jensen and Mazaheri, 2010). However, the precise temporal and spatial relationships between the modulatory function implemented by alpha oscillations and population-level cortical activity remained undefined. Furthermore, while several studies suggested that alpha power indexes task-related populations across large and spatially separated cortical areas, it was largely unclear whether alpha power also differentially indexes smaller networks of task-related neuronal populations. Here we addressed these questions by investigating the temporal and spatial relationships of electrocorticographic (ECoG) power modulations in the alpha band and in the broadband gamma range (70-170Hz, indexing population-level activity) during auditory and motor tasks in five human subjects and one macaque monkey. In line with previous research, our results confirm that broadband gamma power accurately tracks task-related behavior and that alpha power decreases in task-related areas. More importantly, they demonstrate that alpha power suppression lags population-level activity in auditory areas during the auditory task, but precedes it in motor areas during the motor task. This suppression of alpha power in task-related areas was accompanied by an increase in areas not related to the task. In addition, we show for the first time that these differential modulations of alpha power could be observed not only across widely distributed systems (e.g., motor vs. auditory system), but also within the auditory system. Specifically, alpha power was suppressed in the locations within the auditory system that most robustly responded to particular sound stimuli. Altogether, our results provide experimental evidence for a mechanism that preferentially recruits task-related neuronal populations by increasing cortical excitability in task-related cortical areas and decreasing cortical excitability in task-unrelated areas. This mechanism is implemented by variations in alpha power and is common to humans and the non-human primate under study. These results contribute to an increasingly refined understanding of the mechanisms underlying the selection of the specific neuronal populations required for task execution.

Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.

Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions.

The global burden of major infectious complications following prostate biopsy.

We present a systematic review providing estimates of the overall and regional burden of infectious complications following prostate biopsy. A directly standardized prevalence estimate was used because it reflects the burden of disease more explicitly. Complications included sepsis, hospitalization, bacteraemia, bacteriuria, and acute urinary retention after biopsy. There were 165 articles, comprising 162 577 patients, included in the final analysis. Our findings demonstrate that transrectal biopsy was associated with a higher burden of hospitalization (1·1% vs. 0·9%) and sepsis (0·8% vs. 0·1%) compared to transperineal biopsy, while acute urinary retention was more prevalent after transperineal than transrectal biopsy (4·2% vs. 0·9%). The differences were statistically non-significant because of large heterogeneity across countries. We also demonstrate and discuss regional variations in complication rates, with Asian studies reporting higher rates of sepsis and hospitalization.

Parametric variation of gamma frequency and power with luminance contrast: A comparative study of human MEG and monkey LFP and spike responses.

Gamma oscillations contribute significantly to the manner in which neural activity is bound into functional assemblies. The mechanisms that underlie the human gamma response, however, are poorly understood. Previous computational models of gamma rely heavily on the results of invasive recordings in animals, and it is difficult to assess whether these models hold in humans. Computational models of gamma predict specific changes in gamma spectral response with increased excitatory drive. Hence, differences and commonalities between spikes, LFPs and MEG in the spectral responses to changes in excitatory drive can lead to a refinement of existing gamma models. We compared gamma spectral responses to varying contrasts in a monkey dataset acquired previously (Roberts et al., 2013) with spectral responses to similar contrast variations in a new human MEG dataset. We found parametric frequency shifts with increasing contrast in human MEG at the single-subject and the single-trial level, analogous to those observed in the monkey. Additionally, we observed parametric modulations of spectral asymmetry, consistent across spikes, LFP and MEG. However, while gamma power scaled linearly with contrast in MEG, it saturated at high contrasts in both the LFP and spiking data. Thus, while gamma frequency changes to varying contrasts were comparable across spikes, LFP and MEG, gamma power changes were not. This indicates that gamma frequency may be a more stable parameter across scales of measurements and species than gamma power. The comparative approach undertaken here represents a fruitful path towards a better understanding of gamma oscillations in the human brain.

Safety culture and the 5 steps to safer surgery: an intervention study.

BACKGROUND: Improvements in safety culture have been postulated as one of the mechanisms underlying the association between the introduction of the World Health Organisation (WHO) Surgical Safety Checklist with perioperative briefings and debriefings, and enhanced patient outcomes. The 5 Steps to Safer Surgery (5SSS) incorporates pre-list briefings, the three steps of the WHO Surgical Safety Checklist (SSC) and post-list debriefings in one framework. We aimed to identify any changes in safety culture associated with the introduction of the 5SSS in orthopaedic operating theatres. METHODS: We assessed the safety culture in the elective orthopaedic theatres of a large UK teaching hospital before and after introduction of the 5SSS using a modified version of the Safety Attitude Questionnaire - Operating Room (SAQ-OR). Primary outcome measures were pre-post intervention changes in the six safety culture domains of the SAQ-OR. We also analysed changes in responses to two items regarding perioperative briefings. RESULTS: The SAQ-OR survey response rate was 80% (60/75) at baseline and 74% (53/72) one yr later. There were significant improvements in both the reported frequency (P<0.001) and perceived importance (P=0.018) of briefings, and in five of the six safety culture domain scores (Working Conditions, Perceptions of Management, Job Satisfaction, Safety Climate and Teamwork Climate) of the SAQ-OR (P<0.001 in all cases). Scores in the sixth domain (Stress Recognition) decreased significantly (P=0.028). CONCLUSIONS: Implementation of the 5SSS was associated with a significant improvement in the safety culture of elective orthopaedic operating theatres.

Acetylcholine contributes through muscarinic receptors to attentional modulation in V1.

Attention exerts a strong influence over neuronal processing in cortical areas. It selectively increases firing rates and affects tuning properties, including changing receptive field locations and sizes. Although these effects are well studied, their cellular mechanisms are poorly understood. To study the cellular mechanisms, we combined iontophoretic pharmacological analysis of cholinergic receptors with single cell recordings in V1 while rhesus macaque monkeys (Macaca mulatta) performed a task that demanded top-down spatial attention. Attending to the receptive field of the V1 neuron under study caused an increase in firing rates. Here we show that this attentional modulation was enhanced by low doses of acetylcholine. Furthermore, applying the muscarinic antagonist scopolamine reduced attentional modulation, whereas the nicotinic antagonist mecamylamine had no systematic effect. These results demonstrate that muscarinic cholinergic mechanisms play a central part in mediating the effects of attention in V1.

The relative reliability of actively participating and passively observing raters in a simulation-based assessment for selection to specialty training in anaesthesia.

Selection to specialty training is a high-stakes assessment demanding valuable consultant time. In one initial entry level and two higher level anaesthesia selection centres, we investigated the feasibility of using staff participating in simulation scenarios, rather than observing consultants, to rate candidate performance. We compared participant and observer scores using four different outcomes: inter-rater reliability; score distributions; correlation of candidate rankings; and percentage of candidates whose selection might be affected by substituting participants' for observers' ratings. Inter-rater reliability between observers was good (correlation coefficient 0.73-0.96) but lower between participants (correlation coefficient 0.39-0.92), particularly at higher level where participants also rated candidates more favourably than did observers. Station rank orderings were strongly correlated between the rater groups at entry level (rho 0.81, p < 0.001) but weaker at the two higher level centres (rho 0.52, p = 0.018; rho 0.58, p = 0.001). Substituting participants' for observers' ratings had less effect once scores were combined with those from other selection centre stations. Selection decisions for 0-20% of candidates could have changed, depending on the numbers of training posts available. We conclude that using participating raters is feasible at initial entry level only.

Nutritional intake and oxidative stress in chronic heart failure.

BACKGROUND AND AIMS: Patients with chronic heart failure (CHF) are known to be at risk of malnutrition, and cardiac cachexia is an adverse prognostic indicator. The aim of this study was to determine the dietary adequacy of CHF patients compared with Dietary Reference Values, to compare the nutritional intake and status of CHF patients to a healthy comparison group, and finally to determine whether nutritional intake and status depended on New York Heart Association (NYHA) functional class. METHODS AND RESULTS: Patients with CHF (n = 39) and a comparison group of 27 healthy participants, who did not have CHF, were asked to complete a four-day food diary, and energy and nutrient intakes were calculated. F(2α)-isoprostanes were measured in urine as an indicator of oxidative stress and antioxidants were measured in serum or plasma. Overall 73% of the CHF patients were consuming less than recommended energy intakes, and more than 50% of these patients were also consuming less than recommended vitamin D, selenium and zinc intakes. Nutrient intake (energy, vitamin B6, D, E, iron, folate and riboflavin) was lower in CHF patients than in the comparison group, with vitamin B6 and folate intake and antioxidant status decreasing, and isoprostane status increasing as NYHA functional class increased. CONCLUSION: The majority of CHF patients do not meet dietary reference values for energy and a range of nutrients, and nutrient intake is lower in CHF patients than in healthy individuals. Dietary inadequacy tends to be increased in those with more severe disease.

Development of workplace-based assessments of non-technical skills in anaesthesia.

Non-technical skills are recognised as crucial to good anaesthetic practice. We designed and evaluated a specialty-specific tool to assess non-technical aspects of trainee performance in theatre, based on a system previously found reliable in a recruitment setting. We compared inter-rater agreement (multir-ater kappa) for live assessments in theatre with that in a selection centre and a video-based rater training exercise. Twenty-seven trainees participated in the first in-theatre assessment round and 40 in the second. Round- 1 scores had poor inter-rater agreement (mean kappa = 0.20) and low reliability (generalisability coefficient G = 0.50). A subsequent assessor training exercise showed good inter-rater agreement, (mean kappa = 0.79) but did not improve performance of the assessment tool when used in round 2 (mean kappa = 0.14, G = 0.42). Inter-rater agreement in two selection centres (mean kappa = 0.61 and 0.69) exceeded that found in theatre. Assessment tools that perform reliably in controlled settings may not do so in the workplace.

Frontal sinus fracture management: a systematic review and meta-analysis.

A systematic review of the frontal sinus fracture management literature was undertaken to document measurable outcomes, with emphasis on complications associated with the various treatment strategies. A comprehensive electronic search was undertaken in October 2018. Randomized controlled trials (RCT), controlled clinical trials, retrospective and prospective studies describing the management of frontal sinus fractures and complications were included. Twenty-four publications were included: one reporting a prospective RCT and 23 reporting consecutive case series studies (four prospective, 19 retrospective). These included 2388 patients (84.1% male, average age 23-43 years); 50.7% of cases were due to motor vehicle accidents and 61.8% had a concomitant intracranial injury. There were six categories for anterior table reconstruction, three endoscopic surgery categories, 11 for obliteration, and six for cranialization. Forest plots demonstrating complications based on the Clavien-Dindo classification of 1 ('low') and >3 ('high') were determined for total, early, and late complications, with heterogeneous effect sizes. Fractures with a nasofrontal outflow tract (NFOT) injury without obstruction can be treated with reconstruction if displaced, or managed conservatively if undisplaced. Obliteration and cranialization should be considered when there is obstruction of the NFOT. A computed tomography scan should be performed at 6 months to evaluate re-ventilation of the sinus. Endoscopic sinus surgery is a reasonable salvage re-ventilation procedure.

Predictive validity of a selection centre testing non-technical skills for recruitment to training in anaesthesia.

BACKGROUND: Assessment centres are an accepted method of recruitment in industry and are gaining popularity within medicine. We describe the development and validation of a selection centre for recruitment to speciality training in anaesthesia based on an assessment centre model incorporating the rating of candidate's non-technical skills. METHODS: Expert consensus identified non-technical skills suitable for assessment at the point of selection. Four stations-structured interview, portfolio review, presentation, and simulation-were developed, the latter two being realistic scenarios of work-related tasks. Evaluation of the selection centre focused on applicant and assessor feedback ratings, inter-rater agreement, and internal consistency reliability coefficients. Predictive validity was sought via correlations of selection centre scores with subsequent workplace-based ratings of appointed trainees. RESULTS: Two hundred and twenty-four candidates were assessed over two consecutive annual recruitment rounds; 68 were appointed and followed up during training. Candidates and assessors demonstrated strong approval of the selection centre with more than 70% of ratings 'good' or 'excellent'. Mean inter-rater agreement coefficients ranged from 0.62 to 0.77 and internal consistency reliability of the selection centre score was high (Cronbach's α=0.88-0.91). The overall selection centre score was a good predictor of workplace performance during the first year of appointment. CONCLUSIONS: An assessment centre model based on the rating of non-technical skills can produce a reliable and valid selection tool for recruitment to speciality training in anaesthesia. Early results on predictive validity are encouraging and justify further development and evaluation.

The clinical efficacy of PSMA PET/MRI in biochemically recurrent prostate cancer compared with standard of care imaging modalities and confirmatory histopathology: results of a single-centre, prospective clinical trial.

Prospective evidence for the clinical role and efficacy of prostate specific membrane antigen (PSMA) positron emission tomography (PET)/magnetic resonance imaging (MRI) combining MRI characterization and localization of lesions with PET avidity in comparison to conventional imaging is limited. In a prospective clinical trial, we aimed to evaluate the diagnostic yield and therapeutic impact of PSMA PET/MRI in men with biochemical recurrence (BCR) following curative therapy. A single-centre, prospective clinical trial at the Princess Alexandra Hospital recruited 30 patients with BCR. Patients underwent PSMA PET/MRI and concurrent conventional CT chest, abdomen, pelvis and whole-body bone scan. Biopsy was performed when safety possible for histological correlation of identified lesions. Clinical efficacy and impact of PSMA PET findings were evaluated. 30 patients with BCR were recruited (median PSA 0.69 ng/ml). PSMA avid lesions were present in 21 patients (70%). 23 patients were previously treated with definitive surgery, 6 patients received external beam radiotherapy and 1 patient had low dose rate brachytherapy. A total of 8 of 9 lesions biopsied were positive (88.9% histological correlation). PSMA PET/MRI detected local recurrence (p = 0.005) and pelvic lesions (p = 0.06) more accurately than conventional imaging. PSMA PET/MRI may be useful in staging men with biochemical recurrence, especially when PSA is low. Our data demonstrates a high detection rate, especially for locally recurrent disease, and highlights the role of this modality when PSA is low. This modality has the potential to significantly improve prostate cancer detection and may have implications for earlier salvage treatment, avoidance of futile local therapy and change patient management to lead to improved outcomes.

Attention and contrast differently affect contextual integration in an orientation discrimination task.

Attention is often regarded as a mechanism by which attended objects become perceptually more salient, akin to increasing their contrast. We demonstrate that attention is better described as a mechanism by which task relevant information impacts on ongoing processing, while excluding task irrelevant information. We asked subjects to judge the orientation of a target relative to a reference, in a single and dual task setting. The target orientation percept was systematically influenced by the presentation of prior spatio-temporal context. We found that the sign of the context influence depended on target contrast, but its strength depended on the level of attention devoted to the task. Thus the effects of attention and contrast were fundamentally different; contrast influenced the sign of contextual interactions, while attention suppressed these interactions irrespective of their sign.

Evidence for inhibited diffraction of light propagating through nanolaminate metallodielectric material.

We report the fabrication and characterization of laterally continuous silver layers alternated with glassy amorphous polycarbonate films with the thickness of each layer much less than the wavelength. Such films exhibit physical phenomena associated with the coupled plasmon resonances. We have characterized light propagation through the resulting metal-dielectric (MD) periodic structures using collection mode Near Field Scanning Optical Microscopy (NSOM). In agreement with published theoretical models, our experiments provide evidence that diffraction can be inhibited for light propagating through metallodielectric nanolaminate.

Military intensive care part 1. A historical review.

ICU is a product of clinical developments, technological advances, social changes and history. Military ICU reflects all of these as well as deployed operational experience. Having considered how military ICU got to where it is, the next article will consider current practice.

Total temporomandibular joint replacement prostheses: a systematic review and bias-adjusted meta-analysis.

The aim of the present study was to determine which prosthesis has resulted in the best outcomes after total temporomandibular joint replacement (TMJR). A comprehensive electronic search was undertaken in September 2015. Inclusion criteria encompassed studies that described one of the three current TMJR systems and that had pre- and postoperative data on at least two of the following TMJR indications: pain, diet, function, and maximum inter-incisal opening (MIO). Sixteen papers were included in the systematic review, reporting 10 retrospective studies and six prospective studies (no randomized controlled or case-controlled trials). A total 312 patients with 505 TMJ Concepts prostheses, 728 patients with 1048 Biomet prostheses, and 125 patients with 196 Nexus prostheses were included in the analysis. There was no real difference between the various TMJR systems in terms of pain or diet scores. Function scores improved with the TMJ Concepts, but this was the only prosthesis for which data were available. Biomet prostheses appeared to have a greater increase in MIO mean gain compared to TMJ Concepts and Nexus prostheses; however this was heavily biased by one study. Without this study, there was no real difference in MIO. It is concluded that the prostheses are similar, but most data are available for the TMJ Concepts prosthesis, with results being favourable.

A novel electrode-pipette design for simultaneous recording of extracellular spikes and iontophoretic drug application in awake behaving monkeys.

We developed a novel design of an electrode-pipette combination (EPC) which allows access to brain structures in awake behaving primates without the need for guide tubes or to mechanically open the dura prior to electrode insertion. The EPC consists of an etched tungsten in glass electrode flanked by two pipettes which allow for local and highly controlled iontophoretic administration of neuroactive substances. These EPCs have excellent single cell isolation properties and are sturdy enough to penetrate the primate dura for up to 8 weeks following either a craniotomy or a dura scrape (i.e. even after substantial built up of fibrous scar tissue). We show that the EPCs can be used to selectively manipulate the cholinergic system in primate V1 during passive fixation and while animals perform an attentionally demanding task.

Summarization of Injury and Fatality Factors Involving Children and Youth in Grain Storage and Handling Incidents.

This article summarizes data gathered on 246 documented cases of children and youth under the age of 21 involved in grain storage and handling incidents in agricultural workplaces from 1964 to 2013 in the U.S. that have been entered into the Purdue Agricultural Confined Space Incident Database. The database is the result of ongoing efforts to collect and file information on documented injuries, fatalities, and entrapments in all forms of agricultural confined spaces. While the frequency of injuries and fatalities involving children and youth in agriculture has decreased in recent years, incidents related to agricultural confined spaces, especially grain storage and handling facilities, have remained largely unchanged during the same period. Approximately 21% of all documented incidents involved children and youth (age 20 and younger), and more than 77% of all documented incidents were fatal, suggesting an under-reporting of non-fatal incidents. Findings indicate that the majority of youth incidents occurred at OSHA exempt agricultural worksites. The states reporting the most incidents were Indiana, Iowa, Nebraska, Illinois, and Minnesota. Grain transport vehicles represented a significant portion of incidents involving children under the age of 16. The overwhelming majority of victims were male, and most incidents (50%) occurred in June, October, and November. Recommendations include developing intervention strategies that target OSHA exempt farms, feedlots, and seed processing facilities; preparing engineering design and best practice standards that reduce the exposure of children and youth to agricultural confined spaces; and developing gender-specific safety resources that incorporate gender-sensitive strategies to communicate safety information to the population of young males with the greatest risk of exposure to the hazards of agricultural confined spaces.

Efficacy of 100 mg of double-bolus alteplase in achieving complete perfusion in the treatment of acute myocardial infarction.

OBJECTIVES: The purpose of this study was to assess the efficacy of 150 mg of aspirin plus 100 mg of alteplase, administered as two intravenous bolus injections of 50 mg each given 30 min apart, and followed by intravenous heparin, on infarct-related coronary artery patency (Thrombolysis in Myocardial Infarction [TIMI] flow grade 3). BACKGROUND: Previous workers have shown in animals that reducing the duration of an infusion of recombinant tissue-type plasminogen activator increases the initial rate of thrombolysis, resulting in high early infarct-related coronary artery patency rates. The logical progression of this idea is bolus administration. METHODS: Consecutive patients presenting up to 6 h from the onset of symptoms were recruited for the study. Angiography was performed at 60 and 90 min after the first bolus and between 19 to 48 h after study entry. Patients were followed up for 1 month. RESULTS: At 60 min, angiography revealed infarct-related coronary artery patency of TIMI flow grade 3 in 55 (86%) of 64 patients (95% confidence interval [CI] 75% to 93%) and TIMI flow grade 2 or 3 in 58 (91%) of 64 patients (95% CI 81% to 97%). At 90 min, infarct-related artery patency of TIMI flow grade 3 was achieved in 74 (88%) of 84 patients (95% CI 79% to 94%) and TIMI flow grade 2 or 3 in 78 (93%) of 84 patients (95% CI 85% to 97%). Two patients (2.4%) had early angiographic reocclusion whereas 10 (11.9%) had late reinfarction. Bleeding episodes were mostly minor, and there was no cerebrovascular bleeding. Five patients (6.0%) died within 1 month of the acute myocardial infarction. CONCLUSIONS: In 84 patients with acute myocardial infarction, administration of 100 mg of double-bolus (2 x 50 mg) alteplase, aspirin and heparin is associated with remarkably high early infarct-related coronary artery patency rates (TIMI flow grade 3) of 86% and 88%, respectively, at 60 and 90 min.