A Multicenter, Controlled Human Infection Study of Influenza A(H1N1)pdm09 in Healthy Adults

BACKGROUND

We evaluated the associations between baseline influenza virus-specific hemagglutination inhibition (HAI) and microneutralization (MN) titers and subsequent symptomatic influenza virus infection in a controlled human infection study.

METHODS

We inoculated unvaccinated healthy adults aged 18-49 years with an influenza A/California/04/2009/H1N1pdm-like virus (NCT04044352). We collected serial safety labs, serum for HAI and MN, and nasopharyngeal swabs for reverse-transcription polymerase chain reaction (RT-PCR) testing. Analyses used the putative seroprotective titer of ≥40 for HAI and MN. The primary clinical outcome was mild-to-moderate influenza disease (MMID), defined as ≥1 postchallenge positive qualitative RT-PCR test with a qualifying symptom/clinical finding.

RESULTS

Of 76 participants given influenza virus challenge, 54 (71.1%) experienced MMID. Clinical illness was generally very mild. MMID attack rates among participants with baseline titers ≥40 by HAI and MN were 64.9% and 67.9%, respectively, while MMID attack rates among participants with baseline titers <40 by HAI and MN were 76.9% and 78.3%, respectively. The estimated odds of developing MMID decreased by 19% (odds ratio, 0.81 [95% confidence interval, .62-1.06]; P = .126) for every 2-fold increase in baseline HAI. There were no significant adverse events.

CONCLUSIONS

We achieved a 71.1% attack rate of MMID. High baseline HAI and MN were associated with protection from illness. Clinical Trials Registration. NCT04044352.

Patient handoffs and multi-specialty trainee perspectives across an institution: informing recommendations for health systems and an expanded conceptual framework for handoffs

BACKGROUND

Safe and effective physician-to-physician patient handoffs are integral to patient safety. Unfortunately, poor handoffs continue to be a major cause of medical errors. Developing a better understanding of challenges faced by health care providers is critical to address this continued patient safety threat. This study addresses the gap in the literature exploring broad, cross-specialty trainee perspectives around handoffs and provides a set of trainee-informed recommendations for both training programs and institutions.

METHODS

Using a constructivist paradigm, the authors conducted a concurrent/embedded mixed method study to investigate trainees' experiences with patient handoffs across Stanford University Hospital, a large academic medical center. The authors designed and administered a survey instrument including Likert-style and open-ended questions to solicit information about trainee experiences from multiple specialties. The authors performed a thematic analysis of open-ended responses.

RESULTS

687/1138 (60.4%) of residents and fellows responded to the survey, representing 46 training programs and over 30 specialties. There was wide variability in handoff content and process, most notably code status not being consistently mentioned a third of the time for patients who were not full code. Supervision and feedback about handoffs were inconsistently provided. Trainees identified multiple health-systems level issues that complicated handoffs and suggested solutions to these threats. Our thematic analysis identified five important aspects of handoffs: (1) handoff elements, (2) health-systems-level factors, (3) impact of the handoff, (4) agency (duty), and (5) blame and shame.

CONCLUSIONS

Health systems, interpersonal, and intrapersonal issues affect handoff communication. The authors propose an expanded theoretical framework for effective patient handoffs and provide a set of trainee-informed recommendations for training programs and sponsoring institutions. Cultural and health-systems issues must be prioritized and addressed, as an undercurrent of blame and shame permeates the clinical environment.

Clinical endpoints to inform vaccine policy: A systematic review of outcome measures from pediatric influenza vaccine efficacy trials

INTRODUCTION

We conducted a systematic review of pediatric influenza vaccine efficacy trials to assess clinical outcome measures and whether the trials defined important public health endpoints.

MATERIAL AND METHODS

We systematically identified phase 3 or 4 influenza vaccine randomized controlled trials among children ≤18 years of age with laboratory-confirmed influenza outcomes since 1980. We recorded countries, age groups, vaccine formulations, specimen collection criteria, laboratory diagnostics, primary and secondary outcome measures, and funders, and we determined income category for study countries. We used descriptive statistics to summarize study characteristics. We analyzed the studies overall and a subset of studies conducted in at least one low- and middle-income country (LMIC).

RESULTS

From 6455 potentially relevant articles, we identified 41 eligible studies. Twenty-one studies (51%) were conducted in at least one LMIC, while the remaining studies (49%) were conducted in high-income countries only. Thirty-one studies (76%) included children younger than six years. We found 40 different primary outcome measures among the 41 eligible studies. Thirty-three studies (80%) reported standardized symptoms or findings which defined a primary outcome or triggered specimen collection. One study defined a primary outcome which captured more severe illness; however, cases were mostly due to high body temperature without other severity criteria. Of the 21 studies from at least one LMIC, 15 (71%) were published since 2010 and 17 (81%) enrolled children younger than six years. Eighteen (86%) studies from at least one LMIC reported standardized symptoms or findings which defined a primary outcome or triggered specimen collection.

CONCLUSIONS

Among pediatric influenza vaccine efficacy trials, primary outcome measures and clinical specimen collection criteria were highly variable and, with one exception, focused on capturing any influenza illness. As most LMICs do not have influenza vaccination programs, our study highlights a potential data limitation affecting policy and implementation decisions in these settings.

Mastery learning improves simulated central venous catheter insertion by emergency medicine teaching faculty

OBJECTIVES

Routine competency assessments of procedure skills, such as central venous catheter (CVC) insertion, do not occur beyond residency training. Evidence suggests variable, suboptimal attending physician procedure skills. Our study aimed to assess CVC insertion skill by academic emergency physicians, determine whether a simulation-based mastery learning (SBML) intervention improves performance and investigate for variables that predict competence.

METHODS

This is a pretest-posttest study that evaluated simulated CVC insertion by emergency medicine (EM) faculty physicians. We assessed 44 volunteer participants at a large academic medical center over a 1-month period using a published 29-item checklist. Our primary outcome was the difference in assessment score before and after a SBML intervention. A secondary analysis evaluated predictors of pretest performance.

RESULTS

A total of 44 subjects participated. Only four of 44 (9.1%) of subjects met a predefined minimum passing score on pretest. Mean assessment scores increased by 21.5% following the SBML intervention (95% confidence interval [CI] of the difference = 18.1% to 24.8%, p < 0.001). In a regression model, pretest scores increased by 10.8% (95% CI = 2.9 to 18.7%, p = 0.009) if subjects completed postgraduate training within 5 years. Frequency of CVC insertion did not predict performance, but 25 of 44 (56.8%) faculty members had no documented performance or supervision of a CVC insertion within 1 year of assessment.

CONCLUSIONS

SBML is a promising method to assess and improve CVC insertion performance by EM faculty physicians. Recent completion of postgraduate training was a significant predictor of CVC insertion performance. Our results require validation in larger cohorts of EM physicians across other academic institutions.

The operational feasibility of vaccination programs targeting influenza risk groups in the WHO African and South-East Asian Regions

BACKGROUND

Influenza vaccination is uncommon in low-resource settings. We evaluated aspects of operational feasibility of influenza vaccination programs targeting risk groups in the WHO African (AFR) and South-East Asian (SEAR) Regions.

METHODS

We estimated routine immunization and influenza vaccination campaign doses, doses per vaccinator, and cold storage requirements for one simulated country in each region using evidence-based population distribution, vaccination schedule, and vaccine volumes. Influenza vaccination targeted persons <5 years, pregnant women, persons with chronic diseases, persons ≥65 years, and healthcare workers (HCW). For the AFR country, we compared vaccine volumes to actual storage capacities.

RESULTS

Targeting HCW had a small operational impact, and subsequent findings exclude this group. During three-month influenza vaccination campaigns, monthly doses delivered in the AFR country increased from 15.0% for ≥65 years to 93.1% for <5 years and in the SEAR country from 19.6% for pregnant women to 145.0% for persons with chronic diseases. National-level cold storage capacity requirements increased in the AFR country from 4.1% for ≥65 years to 20.3% for <5 years and in the SEAR country from 3.9% for pregnant women to 28.8% for persons with chronic diseases. Subnational-level cold storage capacity requirements increased in the AFR country from 5.9% for ≥65 years to 36.8% for <5 years and the SEAR country from 17.6% for pregnant women to 56.0% for persons with chronic diseases.

CONCLUSIONS

Influenza vaccination of most risk groups will require substantial increases in doses, doses per vaccinator, and cold storage capacity in countries where infrastructure and resources are limited.

National routine adult immunisation programmes among World Health Organization Member States: an assessment of health systems to deploy COVID-19 vaccines

Introduction

As SARS-CoV-2 disproportionately affects adults, the COVID-19 pandemic vaccine response will rely on adult immunisation infrastructures.

Aim

To assess adult immunisation programmes in World Health Organization (WHO) Member States.

Methods

We evaluated country reports from 2018 on adult immunisation programmes sent to WHO and UNICEF. We described existing programmes and used multivariable regression to identify independent factors associated with having them.

Results

Of 194 WHO Member States, 120 (62%) reported having at least one adult immunisation programme. The Americas and Europe had the highest proportions of adult immunisation programmes, most commonly for hepatitis B and influenza vaccines (> 47% and > 91% of countries, respectively), while Africa and South-East Asia had the lowest proportions, with < 11% of countries reporting adult immunisation programmes for hepatitis B or influenza vaccines, and none for pneumococcal vaccines. In bivariate analyses, high or upper-middle country income, introduction of new or underused vaccines, having achieved paediatric immunisation coverage goals and meeting National Immunisation Technical Advisory Groups basic functional indicators were significantly associated (p < 0.001) with having an adult immunisation programme. In multivariable analyses, the most strongly associated factor was country income, with high- or upper-middle-income countries significantly more likely to report having an adult immunisation programme (adjusted odds ratio: 19.3; 95% confidence interval: 6.5–57.7).

Discussion

Worldwide, 38% of countries lack adult immunisation programmes. COVID-19 vaccine deployment will require national systems for vaccine storage and handling, delivery and waste management to target adult risk groups. There is a need to strengthen immunisation systems to reach adults with COVID-19 vaccines.

O5: THE CLIFF AND CONOR STUDIES NOVEL ASSESSMENT TOOLS IN COLORECTAL LIVER METASTASES (CLIFF STUDY - CHANGE IN LIVER FUNCTION AND FAT IN PRE-OPERATIVE CHEMOTHERAPY FOR COLORECTAL LIVER METASTASES, CONOR STUDY

Introduction

Hepatic resection is the only potentially curative treatment for patients with colorectal liver metastases (CLM). Patient selection is key, but there is wide variation in practice. Pre-operative chemotherapy can improve oncological outcomes, however chemotherapy-associated liver injury (CALI) may hinder liver regenerative capacity. Standard pre-operative assessments fail to accurately capture factors such as CALI and future liver remnant (FLR) function. The CLiFF and CoNoR studies utilise two novel assessment techniques, aiming to improve patient outcomes.

Method

The CLiFF study prospectively assesses two primary outcomes in 35 patients undergoing pre-operative chemotherapy for CLM: 1) change in liver function (via LiMAx test: direct assessment of hepatic functional capacity), and 2) change in liver fat (via advanced MR imaging (in-house spectroscopy and modified Dixon technique, scaled up via Perspectum LiverMultiScan)). The CoNoR study assesses potential added benefit of these novel tools in CLM resectability decision-making via sequential workstreams: a systematic review and international hepatobiliary expert interviews inform the online survey, assessing added benefit via online MDT scenarios.

Result

Preliminary CLiFF analysis suggests that CALI changes in liver fat and function are unrelated. Liver fat analysis techniques are compared and correlated with digital histological analysis. The CoNoR systematic review identifies key factors influencing CLM resectability decision-making and informs the international expert interviews, scheduled to occur during a February 2020 international hepatobiliary conference.

Conclusion

These studies are the first to assess where these novel tools might be utilised to maximal patient benefit within the Hepatobiliary MDT, and the first systematic review in CLM resectability decision-making.

Take-home message

These two linked studies evaluate the use of two novel assessment tools in the treatment of colorectal liver metastases, with the potential to improve patient selection for curative resection and patient outcomes.

PATEY PRIZE SESSION

The potential effects of deploying SARS-Cov-2 vaccines on cold storage capacity and immunization workload in countries of the WHO African Region

BACKGROUND

SARS-CoV-2 vaccines will be deployed to countries with limited immunization systems.

METHODS

We assessed the effect of deploying SARS-Cov-2 vaccines on cold storage capacity and immunization workload in a simulated WHO African Region country using region-specific data on immunization, population, healthcare workers (HCWs), cold storage capacity (quartile values for national and subnational levels), and characteristics of an approved SARS-CoV-2 vaccine. We calculated monthly increases in vaccine doses, doses per vaccinator, and cold storage volumes for four-month SARS-CoV-2 vaccination campaigns targeting risk groups compared to routine immunization baselines.

RESULTS

Administering SARS-CoV-2 vaccines to risk groups would increase total monthly doses by 27.0% for ≥ 65 years, 91.7% for chronic diseases patients, and 1.1% for HCWs. Assuming median nurse density estimates adjusted for absenteeism and proportion providing immunization services, SARS-CoV-2 vaccination campaigns would increase total monthly doses per vaccinator by 29.3% for ≥ 65 years, 99.6% for chronic diseases patients, and 1.2% for HCWs. When we applied quartiles of actual African Region country vaccine storage capacity, routine immunization vaccine volumes exceeded national-level storage capacity for at least 75% of countries, but subnational levels had sufficient storage capacity for SARS-CoV-2 vaccines for at least 75% of countries.

CONCLUSIONS

In the WHO African Region, SARS-CoV-2 vaccination campaigns would substantially increase doses per vaccinator and cold storage capacity requirements over routine immunization baselines. Pandemic vaccination campaigns would increase storage requirements of national-level stores already at their limits, but sufficient capacity exists at subnational levels. Immediate attention to strengthening immunization systems is essential to support pandemic responses.

Acute respiratory distress syndrome (ARDS) as an adverse event following immunization: Case definition & guidelines for data collection, analysis, and presentation of immunization safety data

This is a Brighton Collaboration Case Definition of the term “Acute Respiratory Distress Syndrome – ARDS” to be utilized in the evaluation of adverse events following immunization. The Case Definition was developed by a group of experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of vaccines for SARS-CoV-2 vaccines and other emerging pathogens. The case definition format of the Brighton Collaboration was followed to develop a consensus definition and defined levels of certainty, after an exhaustive review of the literature and expert consultation. The document underwent peer review by the Brighton Collaboration Network and by selected Expert Reviewers prior to submission. The comments of the reviewers were taken into consideration and edits incorporated in this final manuscript.

The operational impact of deploying SARS-CoV-2 vaccines in countries of the WHO African Region

BACKGROUND

When available, SARS-CoV-2 vaccines will be deployed to countries with limited immunization systems.

METHODS

We conducted an immunization capacity assessment of a simulated WHO African Region country using region-specific data on immunization, population, healthcare workers (HCWs), vaccine cold storage capacity (quartile values for national and subnational levels), and characteristics of influenza vaccines to represent future SARS-CoV-2 vaccines. We calculated monthly increases in vaccine doses, doses per vaccinator, and cold storage volumes for four-month SARS-CoV-2 vaccination campaigns targeting risk groups compared to routine immunization baselines.

FINDINGS

Administering SARS-CoV-2 vaccines to risk groups would increase total monthly doses by 27.0% for ≥65 years, 91.7% for chronic diseases patients, and 1.1% for HCWs. Assuming median nurse density estimates adjusted for absenteeism and proportion providing immunization services, SARS-CoV-2 vaccination campaigns would increase total monthly doses per vaccinator by 29.3% for ≥65 years, 99.6% for chronic diseases patients, and 1.2% for HCWs. When we applied quartiles of actual African Region country vaccine storage capacity, routine immunization vaccine volumes exceeded national-level storage capacity for at least 75% of countries, but subnational levels had sufficient storage capacity for SARS-CoV-2 vaccines for at least 75% of countries.

INTERPRETATION

In the WHO African Region, SARS-CoV-2 vaccination campaigns would substantially increase doses per vaccinator and cold chain capacity requirements over routine immunization baselines. Pandemic vaccination campaigns would add volume to national-level stores already at their limits, but sufficient capacity exists at subnational levels. Immediate attention to strengthening immunization systems is essential to support pandemic responses.

FUNDING

None.

The Utility of Color Doppler to Confirm Endotracheal Tube Placement: A Pilot Study

Introduction

Grayscale ultrasound (US) imaging has been used as an adjunct for confirming endotracheal tube (ETT) placement in recent years. The addition of color Doppler imaging (CDI) has been proposed to improve identification but has not been well studied. The aim of this study was to assess whether CDI improves correct localization of ETT placement.

Methods

A convenience sample of emergency and critical care physicians at various levels of training and experience participated in an online assessment. Participants viewed US video clips of patients, which included either tracheal or esophageal intubations captured in grayscale or with CDI; there were five videos of each for a total of 20 videos. Participants were asked to watch each clip and then assess the location of the ETT.

Results

Thirty-eight subjects participated in the online assessment. Levels of training included medical students (13%), emergency medicine (EM) residents (50%), EM attendings (32%), and critical care attendings (5%). The odds ratio of properly assessing tracheal placement using color relative to a grayscale imaging technique was 1.5 (p = 0.21). Regarding the correct assessment of esophageal placement, CDI had 1.4 times the odds of being correctly assessed relative to grayscale (p = 0.26). The relationship between training level and correct assessments was not significant for either tracheal or esophageal placements.

Conclusion

In this pilot study we found no significant improvement in correct identification of ETT placement using color Doppler compared to grayscale ultrasound; however, there was a trend toward improvement that might be better elucidated in a larger study.

Comparison of the Standardized Video Interview and Interview Assessments of Professionalism and Interpersonal Communication Skills in Emergency Medicine

OBJECTIVES

The Association of American Medical Colleges Standardized Video Interview (SVI) was recently added as a component of emergency medicine (EM) residency applications to provide additional information about interpersonal communication skills (ICS) and knowledge of professionalism (PROF) behaviors. Our objective was to ascertain the correlation between the SVI and residency interviewer assessments of PROF and ICS. Secondary objectives included examination of 1) inter- and intrainstitutional assessments of ICS and PROF, 2) correlation of SVI scores with rank order list (ROL) positions, and 3) the potential influence of gender on interview day assessments.

METHODS

We conducted an observational study using prospectively collected data from seven EM residency programs during 2017 and 2018 using a standardized instrument. Correlations between interview day PROF/ICS scores and the SVI were tested. A one-way analysis of variance was used to analyze the association of SVI and ROL position. Gender differences were assessed with independent-groups t-tests.

RESULTS

A total of 1,264 interview-day encounters from 773 unique applicants resulted in 4,854 interviews conducted by 151 interviewers. Both PROF and ICS demonstrated a small positive correlation with the SVI score (r = 0.16 and r = 0.17, respectively). ROL position was associated with SVI score (p < 0.001), with mean SVI scores for top-, middle-, and bottom-third applicants being 20.9, 20.5, and 19.8, respectively. No group differences with gender were identified on assessments of PROF or ICS.

CONCLUSIONS

Interview assessments of PROF and ICS have a small, positive correlation with SVI scores. These residency selection tools may be measuring related, but not redundant, applicant characteristics. We did not identify gender differences in interview assessments.

Critical care capacity in Haiti: A nationwide cross-sectional survey

OBJECTIVE

Critical illness affects health systems globally, but low- and middle-income countries (LMICs) bear a disproportionate burden. Due to a paucity of data, the capacity to care for critically ill patients in LMICs is largely unknown. Haiti has the lowest health indices in the Western Hemisphere. In this study, we report results of the first known nationwide survey of critical care capacity in Haiti.

DESIGN

Nationwide, cross-sectional survey of Haitian hospitals in 2017-2018.

SETTING

Haiti.

SUBJECTS

All Haitian health facilities with at least six hospital beds.

INTERVENTIONS

Electronic- and paper-based survey.

RESULTS

Of 51 health facilities identified, 39 (76.5%) from all ten Haitian administrative departments completed the survey, reporting 124 reported ICU beds nationally. Of facilities without an ICU, 20 (83.3%) care for critically ill patients in the emergency department. There is capacity to ventilate 62 patients nationally within ICUs and six patients outside of the ICU. One-third of facilities with ICUs report formal critical care training for their physicians. Only five facilities met criteria for a Level 1 ICU as defined by the World Federation of Societies of Intensive and Critical Care Medicine. Self-identified barriers to providing more effective critical care services include lack of physical space for critically ill patients, lack of equipment, and few formally trained physicians and nurses.

CONCLUSIONS

Despite a high demand for critical care services in Haiti, current capacity remains insufficient to meet need. A significant amount of critical care in Haiti is provided outside of the ICU, highlighting the important overlap between emergency and critical care medicine in LMICs. Many ICUs in Haiti lack basic components for critical care delivery. Streamlining critical care services through protocol development, education, and training may improve important clinical outcomes.

The Birth of a Return to work Policy for New Resident Parents in Emergency Medicine

OBJECTIVE

With the rising number of female physicians, there will be more children than ever born in residency, and the current system is inadequate to handle this increase in new resident parents. Residency is stressful and rigorous in isolation, let alone when pregnant or with a new child. Policies that ease these stressful transitions are generally either insufficient or do not exist. Therefore, we created a comprehensive return-to-work policy for resident parents and piloted its implementation. Our policy aims to: 1) establish a clear, shared understanding of the regulatory and training requirements as they pertain to parental leave; 2) facilitate a smooth transition for new parents returning to work; and 3) summarize the local and institutional resources available for both males and females during residency training.

METHOD

In Fall 2017, a task force was convened to draft a return-to-work policy for new resident parents. The task force included nine key stakeholders (i.e., residents, faculty, and administration) at our institution and was made up of three graduate medical education (GME) program directors, a vice chair of education, a designated institutional official (DIO), a chief resident, and three members of our academic department's faculty affairs committee. The task force was selected because of individual expertise in gender equity issues, mentorship of resident parents, GME, and departmental administration.

RESULTS

After development, the policy was piloted from November 2017 to June 2018. Our pilot implementation period included seven new resident parents. All of these residents received schedules that met the return-to-work scheduling terms of our return-to-work policy including no overnight shifts, no sick call, and no more than three shifts in a row. Of equal importance, throughout our pilot, the emergency department schedules at all of our clinical sites remained fully staffed and our sick call pool was unaffected.

CONCLUSION

Our return-to-work policy for new resident parents provides a comprehensive guide to training requirements and family leave policies, an overview of available resources, and a scheduling framework that makes for a smooth transition back to clinical duties.

Needs Assessment of Emergency Department Residents in Examining and Managing Patients with Ophthalmologic Complaints

Purpose Emergency medicine residents are trained to deal with a variety of emergency conditions; eye emergencies represent only a small portion of their clinical experience. This study was a targeted needs assessment of the comfort level of emergency medicine residents in diagnosing and managing patients who present with an ophthalmic chief complaint, with the goal of targeting future educational interventions.

Methods This was a cross sectional survey conducted at a large tertiary-care hospital between June 2016 and August 2016. Participants were 1st, 2nd, or 3rd year emergency medicine residents in an Accreditation Council for Graduate Medical Education (ACGME)-approved emergency medicine residency.

Results The total response rate was 67.4% (29/43). The majority of residents did not expect equivalent availability of ophthalmology consultation services post-graduation. They generally believed ophthalmology and examination skills to be important to their future career and became more comfortable with the slit lamp exam through residency, although the average level of comfort was only 6.9 on a 1 to 10 scale for 3rd year residents (standard deviation [SD] = 2.6). A majority of residents were not confident with their diagnostic, examination, or management skills when queried about specific ophthalmic conditions or presenting symptoms. They indicated a variety of reasons why their comfort with ophthalmologic patients was limited.

Conclusion There is both need and desire for increased ophthalmic skills training for emergency medicine residents. Given time constraints in residency training, possible solutions will need to be innovative and multifaceted in order to target this goal.

Optic Nerve Sheath Diameter Increase on Ascent to High Altitude: Correlation With Acute Mountain Sickness

OBJECTIVES

Elevated optic nerve sheath diameter on sonography is known to correlate with increased intracranial pressure and is observed in acute mountain sickness. This study aimed to determine whether optic nerve sheath diameter changes on ascent to high altitude are associated with acute mountain sickness incidence.

METHODS

Eighty-six healthy adults enrolled at 1240 m (4100 ft), drove to 3545 m (11,700 ft) and then hiked to and slept at 3810 m (12,500 ft). Lake Louise Questionnaire scores and optic nerve sheath diameter measurements were taken before, the evening of, and the morning after ascent.

RESULTS

The incidence of acute mountain sickness was 55.8%, with a mean Lake Louise Questionnaire score ± SD of 3.81 ± 2.5. The mean maximum optic nerve sheath diameter increased on ascent from 5.58 ± 0.79 to 6.13 ± 0.73 mm, a difference of 0.91 ± 0.55 mm (P = .09). Optic nerve sheath diameter increased at high altitude regardless of acute mountain sickness diagnosis; however, compared to baseline values, we observed a significant increase in diameter only in those with a diagnosis of acute mountain sickness (0.57 ± 0.77 versus 0.21 ± 0.76 mm; P = .04). This change from baseline, or Δ optic nerve sheath diameter, was associated with twice the odds of developing acute mountain sickness (95% confidence interval, 1.08-3.93).

CONCLUSIONS

The mean optic nerve sheath diameter increased on ascent to high altitude compared to baseline values, but not to a statistically significant degree. The magnitude of the observed Δ optic nerve sheath diameter was positively associated with acute mountain sickness diagnosis. No such significant association was found between acute mountain sickness and diameter elevation above standard cutoff values, limiting the utility of sonography as a diagnostic tool.

Development and evaluation of standardized narrative cases depicting the general surgery professionalism milestones

PURPOSE

Residency programs now are required to use educational milestones, which has led to the need for new methods of assessment. The literature suggests that narrative cases are a promising tool to track residents' progress. This study demonstrates the process for developing and evaluating narrative cases representing the five levels of the professionalism milestones.

METHOD

In 2013, the authors identified 28 behaviors in the Accreditation Council for Graduate Medical Education general surgery professionalism milestones. They modified previously published narrative cases to fit these behaviors. To evaluate the quality of these cases, the authors developed a 28-item, five-point scale instrument, which 29 interdisciplinary faculty completed. The authors compared the faculty ratings by narrative case and specialty with the authors' initial rankings of the cases by milestone level. They used t tests and analysis of variance to compare mean scores across specialties.

RESULTS

The authors developed 10 narrative cases, 2 for each of the 5 milestone levels. Each case contained at least 20 of the 28 behaviors identified in the milestones. Mean faculty ratings matched the milestone levels. Reliability was good (G coefficient = 0.86, phi coefficient = 0.85), indicating consistency in raters' ability to determine the proper milestone level for each case.

CONCLUSIONS

The authors demonstrate a process for using specialty-specific milestones to develop narrative cases that map to a spectrum of professionalism behaviors. This process can be applied to other competencies and specialties to facilitate faculty awareness of resident performance descriptors and provide a frame of reference for milestones assessment.

Parent Emotion Socialization Practices and Child Self-regulation as Predictors of Child Anxiety: The Mediating Role of Cardiac Variability

The importance of the parent-child relationship in emotional development is well supported. The parental role of facilitating a child's self-regulation may provide a more focused approach for examining the role of parenting in child anxiety. The current study hypothesized that parent emotion socialization practices would predict a child's abilities in self-regulation. Given that physiological arousal has been implicated in emotional development, this was hypothesized to mediate the relationship between parental emotion socialization and child emotion regulation to predict child anxiety. Eighty-five parent and child dyads participated in the study. Parents reporting higher degrees of unsupportive emotion socialization were more likely to have children with fewer abilities in emotion regulation. Cardiac responsiveness mediated the relationship between unsupportive emotion socialization and child emotion regulation. The model of cardiac responsiveness mediating the relationship between unsupportive emotion socialization and child emotion regulation failed to reach statistical significance in predicting child anxiety symptoms.

Prehospital Evaluation of Effusion, Pneumothorax, and Standstill (PEEPS): Point-of-care Ultrasound in Emergency Medical Services

Introduction

In the United States, there are limited studies regarding use of prehospital ultrasound (US) by emergency medical service (EMS) providers. Field diagnosis of life-threatening conditions using US could be of great utility. This study assesses the ability of EMS providers and students to accurately interpret heart and lung US images.

Methods

We tested certified emergency medical technicians (EMT-B) and paramedics (EMT-P) as well as EMT-B and EMT-P students enrolled in prehospital training programs within two California counties. Participants completed a pre-test of sonographic imaging of normal findings and three pathologic findings: pericardial effusion, pneumothorax, and cardiac standstill. A focused one-hour lecture on emergency US imaging followed. Post-tests were given to all EMS providers immediately following the lecture and to a subgroup one week later.

Results

We enrolled 57 prehospital providers (19 EMT-B students, 16 EMT-P students, 18 certified EMT-B, and 4 certified EMT-P). The mean pre-test score was 65.2%±12.7% with mean immediate post-test score of 91.1%±7.9% (95% CI [22%–30%], p<0.001). Scores significantly improved for all three pathologic findings. Nineteen subjects took the one-week post-test. Their mean score remained significantly higher: pre-test 65.8%±10.7%; immediate post-test 90.5%±7.0% (95% CI [19%–31%], p<0.001), one-week post-test 93.1%±8.3% (95% CI [21%–34%], p<0.001).

Conclusion

Using a small sample of EMS providers and students, this study shows the potential feasibility for educating prehospital providers to accurately identify images of pericardial effusion, pneumothorax, and cardiac standstill after a focused lecture.

Change in intraocular pressure during point-of-care ultrasound

INTRODUCTION

Point-of-care ocular ultrasound (US) is a valuable tool for the evaluation of traumatic ocular injuries. Conventionally, any maneuver that may increase intraocular pressure (IOP) is relatively contraindicated in the setting of globe rupture. Some authors have cautioned against the use of US in these scenarios because of a theoretical concern that an US examination may cause or exacerbate the extrusion of intraocular contents. This study set out to investigate whether ocular US affects IOP. The secondary objective was to validate the intraocular pressure measurements obtained with the Diaton® as compared with standard applanation techniques (the Tono-Pen®).

METHODS

We enrolled a convenience sample of healthy adult volunteers. We obtained the baseline IOP for each patient by using a transpalpebral tonometer. Ocular US was then performed on each subject using a high-frequency linear array transducer, and a second IOP was obtained during the US examination. A third IOP measurement was obtained following the completion of the US examination. To validate transpalpebral measurement, a subset of subjects also underwent traditional transcorneal applanation tonometry prior to the US examination as a baseline measurement. In a subset of 10 patients, we obtained baseline pre-ultrasound IOP measurements with the Diaton® and Tono-Pen®, and then compared them.

RESULTS

The study included 40 subjects. IOP values during ocular US examination were slightly greater than baseline (average +1.8mmHg, p=0.01). Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42). In a subset of 10 subjects, IOP values were not significantly different between transpalpebral and transcorneal tonometry (average +0.03mmHg, p=0.07).

CONCLUSION

In healthy volunteer subjects, point-of-care ocular US causes a small and transient increase in IOP. We also showed no difference between the Diaton® and Tono-Pen® methods of IOP measurement. Overall, the resulting change in IOP with US transducer placement is considerably less than the mean diurnal variation in healthy subjects, or pressure generated by physical examination, and is therefore unlikely to be clinically significant. However, it is important to take caution when performing ocular ultrasound, since it is unclear what the change in IOP would be in patients with ocular trauma.

The FAST and E-FAST in 2013: trauma ultrasonography: overview, practical techniques, controversies, and new frontiers

This article reviews important literature on the FAST and E-FAST examinations in adults. It also reviews key pitfalls, limitations, and controversies. A practical "how-to" guide is presented. Lastly, new frontiers are explored.

Cardiac echocardiography

Focused cardiac echocardiography has become a critical diagnostic tool for the emergency physician and critical care physician caring for patients in shock and following trauma to the chest, and those presenting with chest pain and shortness of breath,. Cardiac echocardiography allows for immediate diagnosis of pericardial effusions and cardiac tamponade, evaluation of cardiac contractility and volume status, and detection of right ventricular strain possibly seen with a significant pulmonary embolus. This article addresses how to perform cardiac echocardiography using the standard windows, how to interpret a focused goal-directed examination, and how to apply this information clinically at the bedside.

Exploring patterns in cortisol synchrony among anxious and nonanxious mother and child dyads: a preliminary study

Given that anxiety is highly familial, the current pilot study explored the association between anxiety diagnosis and diurnal cortisol rhythm in mother-child dyads with the hypothesis that a predisposition toward homogenous cortisol profiles may partially explain the familial linkage of anxiety. The role of family environment in stress response was also examined. Participants were 27 mother-child dyads. Results indicated that patterns of cortisol secretion between mother and child are synchronous. Maternal anxiety and aspects of family functioning significantly predicted child awakening cortisol pattern. Further, affective involvement and gender of the child significantly predicted mother-child diurnal cortisol secretion synchrony. These findings provide support for the degree of synchrony in patterns of physiological responsiveness between mother and child, as well as the importance of a child's affective environment in the prediction of a diagnosis of anxiety.

High-precision calibration of MRS thermometry using validated temperature standards: effects of ionic strength and protein content on the calibration

Currently, there is very limited ability to measure the temperature of the brain, but a direct technique for its estimation in vivo could improve the detection of patients at risk of temperature-related brain damage, help in the diagnosis of stroke and tumour, and provide useful information on the mechanisms of thermoregulation of the brain. In this article, new calibrations in vitro of MRS thermometry using temperature-stabilised reference phantoms are reported. The phantoms comprise two concentric glass spheres: the inner sphere contains the phantom material to be measured by MRS, and the outer sphere contains a substance with a known temperature stable to within 0.2 °C. The substances were freezing organic fixed-point compounds (diphenyl ether and ethylene carbonate, freezing at 26.3 and 35.8 °C, respectively) or temperature-controlled circulating water. The phantom temperature was continuously monitored with a fluoroptic probe calibrated at the National Physical Laboratory with traceability to the International Temperature Scale 1990 (ITS-90). The MRS temperature calibration was obtained by measuring the chemical shift of water relative to N-acetylaspartate (NAA) in a single voxel as a function of temperature using a 1.5-T Philips Intera scanner. Measurements were made for several phantom materials to assess the effect of tissue composition on the water-NAA chemical shift against temperature calibration. The phantom mixtures contained 25 mm of NAA buffered to pH 6.5 or 7.5 and several ionic salts or bovine serum albumin (BSA). Spectra were acquired from 25 to 45 °C. The correlation between frequency differences and phantom temperature was very linear with small residuals. However, the linear fitting parameters varied with ionic composition and BSA concentration. The 'apparent' temperature (calibrated using the water-NAA frequency differences) decreased by approximately 1 °C for every 100 mm increase in ionic concentration and increased proportionally to the concentration of BSA.

Developing and assessing initiatives designed to improve clinical teaching performance

To improve the teaching performance of emergency physicians, it is necessary to understand the attributes of expert teachers and the optimal methods to deliver faculty development. A working group of medical educators was formed to review the literature, summarize what is known on the topic, and provide recommendations for future research. This occurred as a track of the 2012 Academic Emergency Medicine (AEM) consensus conference "Education Research in Emergency Medicine: Opportunities, Challenges, and Strategies for Success." The group concluded that the current state of research on these topics is limited. Improvement in understanding will come through research focusing on Kirkpatrick's higher levels of evaluation (behavior and results).

Sonographic Identification of Tube Thoracostomy Study (SITTS): Confirmation of Intrathoracic Placement

INTRODUCTION

Thoracostomy tubes (TT) are commonly placed in the management of surgical, emergency, and trauma patients and chest radiographs (CXR) and computed tomography (CT) are performed to confirm placement. Ultrasound (US) has not previously been used as a means to confirm intrathoracic placement of chest tubes. This study involves a novel application of US to demonstrate chest tubes passing through the pleural line, thus confirming intrathoracic placement.

METHODS

This was an observational proof-of-concept study using a convenience sample of patients with TTs at a tertiary-care university hospital. Bedside US was performed by the primary investigator using first the low-frequency (5-1 MHz) followed by the high-frequency (10-5 MHz) transducers, in both 2-dimensional gray-scale and M-modes in a uniform manner. The TTs were identified in transverse and longitudinal views by starting at the skin entry point and scanning to where the TT passed the pleural line, entering the intrathoracic region. All US images were reviewed by US fellowship-trained emergency physicians. CXRs and CTs were used as the standard for confirmation of TT placement.

RESULTS

Seventeen patients with a total of 21 TTs were enrolled. TTs were visualized entering the intrathoracic space in 100% of cases. They were subjectively best visualized with the high-frequency (10-5 MHz) linear transducer. Sixteen TTs were evaluated using M-mode. TTs produced a distinct pattern on M-mode.

CONCLUSION

Bedside US can visualize the TT and its entrance into the thoracic cavity and it can distinguish it from the pleural line by a characteristic M-mode pattern. This is best visualized with the high-frequency (10-5 MHz) linear transducer.

D-dimer is not elevated in asymptomatic high altitude climbers after descent to 5340 m: the Mount Everest Deep Venous Thrombosis Study (Ev-DVT)

We performed this study to determine the prevalence of elevated D-dimer, a marker for deep venous thrombosis (DVT), in asymptomatic high altitude climbers. On-site personnel enrolled a convenience sample of climbers at Mt. Everest Base Camp (Nepal), elevation 5340 m (17,500 ft), during a single spring climbing season. Subjects were enrolled after descent to base camp from higher elevation. The subjects completed a questionnaire to evaluate their risk factors for DVT. We then performed a D-dimer test in asymptomatic individuals. If the D-dimer test was negative, DVT was considered ruled out. Ultrasound was available to perform lower-extremity compression ultrasounds to evaluate for DVT in case the D-dimer was positive. We enrolled 76 high altitude climbers. None had a positive D-dimer test. The absence of positive D-dimer tests suggests a low prevalence of DVT in asymptomatic high altitude climbers.

Effects of Alzheimer's disease transgenes on neurochemical expression in the mouse brain determined by ¹H MRS in vitro

Transgenic models of human disease can be used to understand pathology and to discover biomarkers of disease presence, progression and response to therapy. Here we report a study of longitudinal metabolic differences between TASTPM transgenic Alzheimer's disease (AD) mice and their wild type counterparts using (1)H magnetic resonance spectroscopy (MRS) to look for potential biomarkers for use in AD research and drug discovery. Chloroform methanol extractions were performed on the brains of mice aged between 3 and 18 months. (1)H MR spectra were recorded from the aqueous fractions. Absolute metabolite concentrations, determined from resonance integrals relative to an internal standard, were analysed by 2-way ANOVA (genotype x age). Significant effects of age alone were identified for creatine, glutamine and total choline-containing compounds. There was a marked increase in creatine in the oldest (15-18 mo) TASTPM mice. The increase in creatine was unexpected and may be caused by osmotic stress in older animals as plaque load increases. Care should be taken when using creatine as a reference metabolite during scans of these animals in vivo. A significant effect of genotype alone was identified for myo-inositol (MI), which was higher in TASTPM mice at all ages. Succinate, glycerophosphocholine and choline all showed significant effects of age and genotype. No significant effects were detected in N-acetylaspartate (NAA) levels. Increased MI could be a marker of gliosis or microglial activation in TASTPM mice, but the absence of an age dependence for MI levels means it may be a biomarker of disease, but not of disease progression. Decreased succinate is indicative of disrupted neuronal energy metabolism, an effect that has been seen in human AD.

Wear and surface analysis of 38 mm ceramic-on-metal total hip replacements under standard and severe wear testing conditions

The purpose of this study was to compare the wear of zirconia-toughened alumina (ZTA) and alumina femoral heads tested against as-cast CoCrMo alloy acetabular cups under both standard and severe wear conditions. A new severe test, which included medio-lateral displacement of the head and rim impact upon relocation, was developed. This resulted in an area of metal transfer and an area of increased wear on the superior-anterior segment of the head that were thought to be due to dislocation and rim impact respectively. While the wear of all ceramic heads was immeasurable using the gravimetric method, the wear rates for the metallic cups from each test were readily calculated. An average steady state wear rate of 0.023 ± 0.005 mm3/106 cycles was found for the cups articulating against ZTA under standard wear conditions. A similar result had previously been obtained for the wear of cups articulated against alumina heads of the same size (within the same laboratory). Under severe wear conditions an increase in the metallic cup steady state wear rate was found with the ZTA and alumina tests giving 0.623 ± 0.252 and 1.35 ± 0.154 mm3/106 cycles respectively. Wear of the ceramic heads was detected using atomic force microscopy which showed, under severe wear conditions, a decrease in polishing marks and occasional grain removal. The surfaces of the ZTA heads tested under standard conditions were virtually unchanged from the unworn samples. Friction tests showed low friction factors for all components, pre and post wear.

Tribological and surface analysis of 38mm alumina–as-cast Co–Cr–Mo total hip arthroplasties

There is currently much discussion over the use of ceramic femoral components against metal acetabular cups, for use in total hip arthroplasty. The current study investigates six hot isostatically pressed alumina femoral heads of 38 mm diameter articulating against six as-cast Co—Cr—Mo metallic acetabular cups. Standard walking-cycle simulator wear testing was carried out to 5×106 cycles using the Durham Mark II hip wear simulator, and wear was determined gravimetrically. In addition, surface topography, using a non-contacting profilometer, an atomic force microscope, and an optical microscope, was monitored throughout the wear test. The wear of the ceramic heads was found to be undetectable using the current gravimetric method; however, a change in the surface topography was seen, as grain removal on the pole was observed through atomic force microscopy analysis. A biphasic wear pattern was found for the metallic cups, with low wear rates of 1.04 ± 0.293 mm3/106 cycles (mean, ±95 per cent confidence interval) and 0.0209 ± 0.004 mm3/106 cycles (mean, ±95 per cent confidence interval) for running-in and steady state wear phases respectively. Frictional measurement revealed that the joints were tending towards full fluid-film lubrication in parts of the walking cycle. The results show that the combination of hot isostatically pressed alumina and as-cast Co—Cr—Mo is a promising alternative for total hip arthroplasties.

A confirmatory factor analysis of the Beck Anxiety Inventory in African American and European American young adults

The anxiety literature is particularly sparse as it relates to African Americans, and there are few studies to date that have examined the factor structure of anxiety assessment tools within this population. The current study investigated the original two-factor structure of the Beck Anxiety Inventory (BAI) in addition to two extant factor structures of the BAI in a non-clinical sample of African American and European American young adults. One hundred twenty one European American and 100 African American young adults completed the BAI. Results of a confirmatory factor analysis indicated that the previous factor structures of the Beck Anxiety Inventory do not provide the best fit for either the African American or the European American sample. An exploratory factor analysis revealed that an alternative, two-factor model provided the best fit for the sample, particularly for the African American sample. Implications and suggestions for future research are discussed.

The assessment of antiangiogenic and antivascular therapies in early-stage clinical trials using magnetic resonance imaging: issues and recommendations

Vascular and angiogenic processes provide an important target for novel cancer therapeutics. Dynamic contrast-enhanced magnetic resonance imaging is being used increasingly to noninvasively monitor the action of these therapeutics in early-stage clinical trials. This publication reports the outcome of a workshop that considered the methodology and design of magnetic resonance studies, recommending how this new tool might best be used.

The development of functional imaging in the diagnosis, management and understanding of childhood brain tumours

Imaging plays a fundamental role in the management of children with brain tumours. A series of new techniques, commonly grouped under the heading functional imaging, promise to give information on the properties and biological characteristics of tissues thereby adding to the structural information available from current imaging. The EPSRC funded a workshop to bring together clinicians from the UK Children's Cancer Study Group and scientific experts in the field to identify clinical problems in childhood brain tumours that may be addressed by functional imaging and to develop a clinical test bed for applying, evaluating and developing this new technology. The presentations and discussion sessions from the workshop are summarised and a review of the current 'state of the art' for this rapidly developing area provided. A key output of the workshop was agreement on a series of hypotheses which can be tested in carefully designed clinical studies.

The 100-day PSA: usefulness as surrogate end point for biochemical disease-free survival after definitive radiotherapy of prostate cancer

Overall and biochemical disease-free (bNED) survival data after definitive radiotherapy (RT) for prostate cancer (CaP) requires decades of patient follow-up. Surrogates involving dynamics of prostate-specific antigen (PSA) decline, PSA nadir and time thereto have been unrewarding. This study investigated the metric of the PSA value 100 days after RT (PSA(100)), analyzed with respect to 8-y bNED survival. A total of 214 patients with T1-3 CaP were treated with definitive RT (defined as dose >66 Gy) in our institution between 1/1/1988 and 12/31/2000. All were subject to continuous follow-up with routine PSA levels. Biochemical failure (77 patients) was defined by the ASTRO criteria (n=67) or by the date of first hormonal therapy for a rising PSA, which did not meet the ASTRO criteria (n=10). No patients were included if they received postoperative radiation, or if hormones were administered prior to bNED recurrence, if any. Patients were stratified by PSA(100) values </= or >4.0 ng/ml, and </= or <2.5 ng/ml. Median follow-up was 64.3 months: follow-up data were calculated as of time to last PSA, with data collection as of 12/31/02. Patients with PSA(100)</=4.0 ng/ml had 62% 8-y bNED survival, and those with PSA(100)>4.0 ng/ml had 20% 8-y bNED survival (P<0.001). Use of a PSA(100) cutoff of 2.5 ng/ml yielded no significant difference in 8-y bNED survival (P=0.229). Cox proportional analysis revealed that initial PSA (P=0.006), stage (P=0.001) and PSA(100)</=4.0 ng/ml (P=0.002) were significantly related to bNED survival, but that age (P=0.887), race (P=0.500), RT dose (P=0.669), Gleason sum (P=0.091), and PSA(100)</=2.5 ng/ml (P=0.128) were not. In conclusion, PSA(100) using a cutoff of 4 ng/ml is a valuable and reliable surrogate for bNED survival after definitive RT, requiring less follow-up than other metrics. Patients with less values will have only about a 1 in 3 chance of bNED failure at 8 y.

Development of vigabatrin-induced lesions in the rat brain studied by magnetic resonance imaging, histology, and immunocytochemistry

Vigabatrin, the gamma-aminobutyric acid transaminase (GABA-T)-inhibiting anticonvulsant drug, was given orally at a dose of 275 mg/kg/day to rats (n = 6) in their feed for a period of 12 weeks, during which T2-weighted magnetic resonance images (MRIs) and diffusion-weighted MRIs (DWIs) were collected at weeks 1, 3, 6, 9, and 12. Half the rats (n = 3; and half their age-matched littermate controls; n = 3) were then killed for histopathological confirmation of the observed VGB-induced cerebellar and cortical white-matter lesions. VGB was removed from the diet and additional MRIs of the remaining rats taken at weeks 14, 17, 20, and 24, at which time they (n = 3), along with remaining controls (n = 3), were also killed for histopathology. The T2-weighted MRIs acquired were used to compute T2 relaxation time maps. Statistically significant VGB-induced T2 increases were observed in the frontal and occipital cortices and in the cerebellar white matter (CWM). The cerebellar lesions were more clearly discerned by eye in the DWIs than by T2-contrast alone. During the recovery period the VGB-treatment group CWM-T2 and CWM-DWI hyperintensity greatly decreased as the reversible lesion disappeared. As expected, histological and immunocytochemical examinations demonstrated the presence of intra-myelinic edema, microvacuolation, and reactive astrocytosis in the CWM and cortex after 12 weeks VGB-treatment. In the remaining animals microvacuolation of the white matter had not completely resolved during the 12-week recovery phase. The data show that quantitative MRI T2-relaxometry can be used to detect VGB-induced CNS pathology, and also suggest that DWI is particularly sensitive to the cerebellar lesion. The reversible neurotoxicity of global GABA-elevation in experimental animals is discussed.

The Kawasaki identity and the Fluctuation Theorem

In this paper we show that the Fluctuation Theorem of Evans and Searles [D. J. Evans, D. J. Searles, Phys. Rev. E 50, 1645 (1994)] implies that the Kawasaki function exp(-Omega(t)) is unity for all time t. We confirm this relationship using experimental data obtained using optical tweezers, and show that the Kawasaki function is a valuable diagnostic tool.

Random packings of spheres and spherocylinders simulated by mechanical contraction

We introduce a simulation technique for creating dense random packings of hard particles. The technique is particularly suited to handle particles of different shapes. Dense amorphous packings of spheres have been formed, which are consistent with the existing work on random sphere packings. Packings of spherocylinders have also been simulated out to the large aspect ratio of alpha=160.0. Our method packs randomly oriented spherocylinders to densities that reproduce experimental results on anisotropic powders and colloids very well. Interestingly, the highest packing density of phi=0.70 is achieved for very short spherocylinders rather than spheres. This suggests that slightly changing the shapes of the particles forming a hard sphere glass could cause it to melt. Comparisons between the equilibrium phase diagram for hard spherocylinders and the densest possible amorphous packings have interesting implications on the crystallization of spherocylinders as a function of aspect ratio.

How hard is a colloidal "hard-sphere" interaction?

Poly-12-hydroxystearic acid (PHSA) is widely used as a coating on colloidal spheres to provide a "hard-sphere-type" interaction. These hard spheres have been widely used in fundamental studies of nucleation, crystallization, and glass formation. Most authors describe the interaction as "nearly" hard sphere. In this paper we directly measure this interaction, using layers of PHSA adsorbed onto mica sheets in a surfaces force apparatus. We find that the layers, in appropriate solvents, have no long-range interaction. When the solvent is decahydronaphthalene (decalin), the repulsion rises from zero to the maximum measurable over a distance range of 15-20 nm. The data is converted to equivalent forces between spheres of different diameters, and modeled using a hard core potential. Using zeroth-order perturbation theory and computer simulation, we demonstrate that the equation of state does not deviate from that of a perfect hard-sphere system under any relevant experimental conditions.

5-HT(2C) receptor activation by m-chlorophenylpiperazine detected in humans with fMRI

Functional brain imaging using selective drug probes offers the opportunity to investigate regional neuronal activation linked to receptor stimulation or inhibition. In a placebo-controlled, balanced order design in eight male volunteers, the 5-HT(2c) agonist, m-chlorophenylpiperazine (mCPP) increased blood oxygen level dependent (BOLD) signal in the hypothalamus, caudate, pallidum, amygdala and pyriform cortex, anterior cingulate gyrus and choroid plexus (p < 0.001 uncorrected), areas with high density of 5-HT(2c) receptors. Activation in the hypothalamus correlated significantly with the prolactin response (p < 0.05 small volume corrected). In a subsequent Go/NoGo task, mCPP enhanced activation in right lateral orbitofrontal cortex (p < 0.05 small volume corrected). These findings suggest that pharmacoMRI is a potentially powerful tool for investigating neurotransmitter function in humans.

In vivo GABA+ measurement at 1.5T using a PRESS-localized double quantum filter

A point-resolved spectroscopy (PRESS)-localized double quantum filter was implemented on a 1.5T clinical scanner for the estimation of gamma-amino butyric acid (GABA) concentrations in vivo. Several calibrations were found to be necessary for consistent results to be obtained. The apparent filter yield was approximately 38%; filter strength was sufficient to reduce the singlet metabolite peaks in vivo to below the level of the noise. Metabolite-nulled experiments were performed, which confirmed that significant overlap occurred between macromolecule signals and the GABA resonance at 3.1 ppm. Although the multiplet arm at 2.9 ppm was confirmed to be relatively free of contamination with macromolecules, some contribution from these and from peptides is likely to remain; therefore, the term GABA+ is used. GABA+ concentrations were estimated relative to creatine (Cr) at the same echo time (TE) in a group of controls, studied on two occasions. The GABA+ concentration in 35-ml regions of interest (ROIs) in the occipital lobe was found to be 1.4 +/- 0.2 mM, with scan-rescan repeatability of 38%.

A comparison of cell and tissue extraction techniques using high-resolution 1H-NMR spectroscopy

Analysis of brain metabolites by a wide range of analytical techniques is typically achieved using biochemical extraction methodologies that require either two separate samples or two separate extraction steps to prepare both aqueous and organic metabolite fractions. However there are a number of brain pathologies in which both aqueous metabolite and lipid changes occur so that a simultaneous extraction of both fractions would be valuable. The methanol-chloroform (M/C) technique enables extraction of both aqueous metabolites and lipids simultaneously. It is already well established for lipid extraction of cells and tissue but its efficiency and reproducibility for extraction of aqueous metabolites is unknown. Therefore, we compared the aqueous metabolite yield and the reproducibility of the M/C method to the commonly used perchloric acid (PCA) method, using 1H-NMR spectroscopy of adult rat brain and purified rat astrocyte culture extracts. The results indicate that M/C is a superior technique for aqueous metabolite extraction from both brain tissue and cells when compared to the PCA method. The M/C extraction technique enables the simultaneous extraction of both lipids and aqueous metabolites from a single sample using small solvent-volumes, making it well suited for NMR investigations of both tissues and cells.

Motions in binary mixtures of hard colloidal spheres: melting of the glass

Dynamic light-scattering experiments are performed on binary mixtures of hard-sphere-like colloidal suspensions with a size ratio of 0.6. The optical properties of the particles are such that the relative contrast of the two species is very sensitive to temperature, a feature that is exploited to obtain the three partial coherent intermediate scattering functions. The glass transition is identified by the onset of structural arrest, or arrest of the alpha process, on the time scale of the experiment. This is observed in a one-component suspension at a packing fraction of 0.575. The intermediate scattering functions measured on the mixtures quantify how, on introduction of the smaller spheres, the alpha process is released, i.e., how the glass melts. Increasing the fraction of smaller particles causes the alpha process to speed up but, at a given wave vector, also incurs a change to its amplitude in proportion to the change in the (partial) structure factor.