Deep Characterisation of the sn-Isomer Lipidome Using High-Throughput Data-Independent Acquisition and Ozone-Induced Dissociation

In recent years there has been a significant interest in the development of innovative lipidomics techniques capable of resolving lipid isomers. To date, methods applied to resolving sn-isomers have resolved only a limited number of species. We report a workflow based on ozone-induced dissociation for untargeted characterisation of hundreds of sn-resolved glycerophospholipid isomers from biological extracts in under 20 min, coupled with an automated data analysis pipeline. It provides an order of magnitude increase in the number of sn-isomer pairs identified as compared to previous reports and reveals that sn-isomer populations are tightly regulated and significantly different between cell lines. The sensitivity of this method and potential for de novo molecular discovery is further demonstrated by the identification of unexpected lipids containing ultra-long monounsaturated acyl chains at the sn-1 position.

Ultrahigh-Mass Resolution Mass Spectrometry Imaging with an Orbitrap Externally Coupled to a High-Performance Data Acquisition System

Matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) is a powerful analytical tool that enables molecular sample analysis while simultaneously providing the spatial context of hundreds or even thousands of analytes. However, because of the lack of a separation step prior to ionization and the immense diversity of biomolecules, such as lipids, including numerous isobaric species, the coupling of ultrahigh mass resolution (UHR) with MSI presents one way in which this complexity can be resolved at the spectrum level. Until now, UHR MSI platforms have been restricted to Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers. Here, we demonstrate the capabilities of an Orbitrap-based UHR MSI platform to reach over 1,000,000 mass resolution in a lipid mass range (600-950 Da). Externally coupling the Orbitrap Q Exactive HF with the high-performance data acquisition system FTMS Booster X2 provided access to the unreduced data in the form of full-profile absorption-mode FT mass spectra. In addition, it allowed us to increase the time-domain transient length from 0.5 to 10 s, providing improvement in the mass resolution, signal-to-noise ratio, and mass accuracy. The resulting UHR performance generates high-quality MALDI MSI images and simplifies the identification of lipids. Collectively, these improvements resulted in a 1.5-fold increase in annotations, demonstrating the advantages of this UHR imaging platform for spatial lipidomics using MALDI-MSI.

Mass Spectrometry Imaging of Lipids Using MALDI Coupled with Plasma-Based Post-Ionization on a Trapped Ion Mobility Mass Spectrometer

Here we report the development and optimization of a mass spectrometry imaging (MSI) platform that combines an atmospheric-pressure matrix-assisted laser desorption/ionization platform with plasma postionization (AP-MALDI-PPI) and trapped ion mobility spectrometry (TIMS). We discuss optimal parameters for operating the source, characterize the behavior of a variety of lipid classes in positive- and negative-ion modes, and explore the capabilities for lipid imaging using murine brain tissue. The instrument generates high signal-to-noise for numerous lipid species, with mass spectra sharing many similarities to those obtained using laser postionization (MALDI-2). The system is especially well suited for detecting lipids such as phosphatidylethanolamine (PE), as well as numerous sphingolipid classes and glycerolipids. For the first time, the coupling of plasma-based postionization with ion mobility is presented, and we show the value of ion mobility for the resolution and identification of species within rich spectra that contain numerous isobaric/isomeric signals that are not resolved in the m/z dimension alone, including isomeric PE and demethylated phosphatidylcholine lipids produced by in-source fragmentation. The reported instrument provides a powerful and user-friendly approach for MSI of lipids.

Non-carious cervical lesions on permanent anterior teeth: a new morphological classification

BACKGROUND

Various cross-sectional forms of non-carious cervical lesions have been described but no formal morphological classification system has been developed. The aims of this study were to describe the spectrum of common morphological forms of non-carious cervical lesions observed within a large sample of extracted human permanent anterior teeth and to develop a system for classification based on morphological features.

METHODS

Over 15,000 extracted permanent anterior teeth were examined macroscopically under illumination at 2x magnification. Well-defined, descriptive categories were formed, based on observable non-carious cervical lesion features and using terminology currently reported in the literature. The lesions were then sorted into these categories.

RESULTS

Five hundred and forty-two non-carious cervical lesions were identified on 15 289 teeth extracted in the early to mid 20th century, representing a frequency of 3.5%. The main categories developed were "shallow", "concave", "wedge-shaped", "notched", and "irregular".

CONCLUSIONS

The new morphological classification system provides an alternative to presently used systems based on aetiology, and should facilitate future research on non-carious cervical lesions.

Non-carious cervical lesions: a scanning electron microscopic study

BACKGROUND

Examining non-carious cervical lesions using scanning electron microscopy (SEM) provides an opportunity to clarify their complex aetiology. This study aimed to examine the morphological forms of non-carious cervical lesions found within a sample of extracted human permanent anterior teeth using scanning electron microscopy.

METHODS

Five examples of non-carious cervical lesions from each of eight different morphologic categories were replicated and examined using scanning electron microscopy.

RESULTS

In total, 40 non-carious cervical lesions were examined at magnifications ranging from 10x to 2605x magnification. Qualitative ultrastructural features evident in the lesions were described and classified according to their appearance. A total of 13 different qualitative features were observed throughout the sample of NCCLs.

CONCLUSIONS

SEM highlighted a broad range of microscopic features of NCCLs, providing valuable insights into their complex, multifactorial aetiology.

Health outcomes. New quality measure for Medicare

OBJECTIVE

A new measurement of health care quality for Medicare beneficiaries has been implemented by the Health Care Financing Administration (HCFA). This paper describes the program, presents baseline data and highlights associated issues.

DESIGN

The Health Outcomes Survey (HOS) is a longitudinal cohort mail survey. Changes in population health status after 2 years will be evaluated on an individual plan level.

SETTING

Two-hundred and eighty-seven US Medicare managed care plans.

MAIN OUTCOMES MEASURES

Physical component and mental component summary scales derived from the SF-36.

FINDINGS

Baseline data documented lower health status in older populations, while functional limitations and disease prevalence were higher. Among different plans, mean functional levels were found to be similar, although a few plans contained populations with exceptionally low levels. These data do not support the assertion that enrolees in for-profit plans are healthier than non-profit plans.

CONCLUSIONS/IMPLICATIONS

The HOS is the first large-scale program to evaluate health outcomes among older Americans. HCFA recognizes several technical and policy issues. Technical issues include possible biased reporting for subpopulations, the validity of proxy responses and respondent burden. Policy issues concern the appropriateness of using a generic measure such as the SF-36 and how much change in health status can be attributed to quality of health care. HCFA plans to extend the HOS to beneficiaries in traditional Medicare. The HOS project is expected to encourage more efforts to maintain or improve the health status of the Medicare managed care population.

A custom confocal and two-photon digital laser scanning microscope

We describe a custom one-photon (confocal) and two-photon all-digital (photon counting) laser scanning microscope. The confocal component uses two avalanche photodiodes (APDs) as the fluorescence detector to achieve high sensitivity and to overcome the limited photon counting rate of a single APD ( approximately 5 MHz). The confocal component is approximately nine times more efficient than our commercial confocal microscope (fluorophore fluo 4). Switching from one-photon to two-photon excitation mode (Ti:sapphire laser) is accomplished by moving a single mirror beneath the objective lens. The pulse from the Ti:sapphire laser is 109 fs in duration at the specimen plane, and average power is approximately 5 mW. Two-photon excited fluorescence is detected by a fast photomultiplier tube. With a x63 1.4 NA oil-immersion objective, the resolution of the confocal system is 0.25 microm laterally and 0.52 microm axially. For the two-photon system, the corresponding values are 0.28 and 0.82 microm. The system is advantageous when excitation intensity must be limited, when fluorescence is low, or when thick, scattering specimens are being studied (with two-photon excitation).

Helping undergraduates repair faulty mental models in the student laboratory

Over half of the undergraduate students entering physiology hold a misconception concerning how breathing pattern changes when minute ventilation increases. Repair of this misconception was used as a measure to compare the impact of three student laboratory protocols on learning by 696 undergraduate students at 5 institutions. Students were tested for the presence of the misconception before and after performing a laboratory activity in which they measured the effect of exercise on tidal volume and breathing frequency. The first protocol followed a traditional written "observe and record" ("cookbook") format. In the second treatment group, a written protocol asked students to complete a prediction table before running the experiment ("predictor" protocol). Students in the third treatment group were given the written "predictor" protocol but were also required to verbalize their predictions before running the experiment ("instructor intervention" protocol). In each of the three groups, the number of students whose performance improved on the posttest was greater than the number of students who performed less well on the posttest (P < 0.001). Thus the laboratory protocols helped students correct the misconception. However, the remediation rate for students in the "instructor intervention" group was more than twice that observed for the other treatment groups (P < 0.001). The results indicate that laboratory instruction is more effective when students verbalize predictions from their mental models than when they only "discover" the outcome of the experiment.

Undergraduate students' misconceptions about respiratory physiology

Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of our misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (approximately 60%) to that seen in a previous study. Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.

How accurate are our assumptions about our students' background knowledge?

Teachers establish prerequisites that students must meet before they are permitted to enter their courses. It is expected that having these prerequisites will provide students with the knowledge and skills they will need to successfully learn the course content. Also, the material that the students are expected to have previously learned need not be included in a course. We wanted to determine how accurate instructors' understanding of their students background knowledge actually was. To do this, we wrote a set of multiple-choice questions that could be used to test students' knowledge of concepts deemed to be essential for learning respiratory physiology. Instructors then selected 10 of these questions to be used as a prerequisite knowledge test. The instructors also predicted the performance they expected from the students on each of the questions they had selected. The resulting tests were administered in the first week of each of seven courses. The results of this study demonstrate that instructors are poor judges of what beginning students know. Instructors tended to both underestimate and overestimate students' knowledge by large margins on individual questions. Although on the average they tended to underestimate students' factual knowledge, they overestimated the students' abilities to apply this knowledge. Hence, the validity of decisions that instructors make, predicated on the basis of their students having the prerequisite knowledge that they expect, is open to question.

Alertenone, a dimer of suberosenone from Alertigorgia sp

Bioassay-guided fractionation of organic extracts of the gorgonian Alertigorgia sp. has yielded the previously known suberosenone (1), a cytotoxic tricyclic sesquiterpene of the quadrone class, and alertenone (2), a dimer of suberosenone. The structure of 2 was determined by spectral analysis; the 1D TOCSY experiment was particularly useful in the structure elucidation. Comparison of the in vitro cytotoxicity of alertenone and suberosenone revealed that the dimeric alertenone was devoid of cytotoxicity below 35 microg/mL. In a hollow-fiber assay model of in vivo activity, suberosenone exhibited some growth inhibition of two of six tumor cell lines tested.

Cardioversion of paroxysmal atrial fibrillation in the emergency department

STUDY OBJECTIVE

Patients presenting to the emergency department with acute atrial fibrillation are traditionally admitted to hospital. The objective of this study was to review the success and safety of ED cardioversion and discharge of patients with acute atrial fibrillation.

METHODS

This health records survey included a cohort sample of consecutive patients presenting with acute atrial fibrillation to the ED of a university-affiliated tertiary hospital. Patients who were in unstable condition on presentation, who had a complicating cardiac diagnosis, or those with other medical or surgical conditions requiring admission were excluded from the study analysis. Patient visit information was entered into a database that included demographics and clinical presentation, investigations, ED therapy, complications, consultations, disposition, and follow up. Patient visits were then categorized into the following groups: no ED intervention, spontaneous resolution, heart rate control, attempted chemical cardioversion, or electrical cardioversion. The data were analyzed using descriptive methods.

RESULTS

Of the 289 eligible patients seen during an 18-month period, 62% (180) underwent attempted chemical cardioversion with a 50% success rate and 28% (80) had attempted electrical cardioversion with a 89% success rate. Ninety-three percent of electrical cardioversions were performed by emergency physicians. There was an overall 6% (19) complication rate, 95% of which were regarded as minor. One patient had a complication caused by a rate control medication, which necessitated hospital admission. Ninety-seven percent (280) of the patients were discharged home directly from the ED.

CONCLUSION

Cardioversion and immediate discharge of patients who present to the ED with acute atrial fibrillation appears to be both safe and effective. This management approach should be prospectively evaluated in multiple settings.

Students' misconceptions about perceived physiological responses

Students' misconceptions about scientific phenomena can arise from at least two possible sources, the students' personal experience with those phenomena and things learned in the classroom. Misconceptions have been studied in a variety of science disciplines, but little attention has been given to the faulty models that students have for physiological processes. In this study 393 undergraduates in three different research universities were asked to predict the changes in heart rate and strength of cardiac contraction and breathing frequency and depth of breathing (physiological parameters that can be directly and personally perceived) under conditions that result in predicted that heart rate would increase but that the strength of contraction would decrease or stay unchanged. Approximately one-half of the students predicted that breathing frequency would increase but depth of breathing would decrease (also erroneous). Explanations for these erroneous predictions were elicited, and the reasons offered revealed significant misconceptions about cardiac and respiratory mechanics. The persistence of such misconceptions was demonstrated in a small group of first-year medical students. A general approach to detecting and remediating misconceptions is discussed.

Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries

CONTEXT

The Ottawa Knee Rule is a previously validated clinical decision rule that was developed to allow physicians to be more selective and efficient in their use of plain radiography for patients with acute knee injuries.

OBJECTIVE

To assess the impact on clinical practice of implementing the Ottawa Knee Rule.

DESIGN

Controlled clinical trial with before-after and concurrent controls.

SETTING

Emergency departments of 2 teaching and 2 community hospitals.

PATIENTS

All 3907 consecutive eligible adults seen with acute knee injuries during two 12-month periods before and after the intervention.

INTERVENTION

During the after period in the 2 intervention hospitals, the Ottawa Knee Rule was taught to all house staff and attending physicians who were encouraged to order knee radiography according to the rule.

MAIN OUTCOME MEASURES

Referral for knee radiography, accuracy and reliability of the rule, mean time in emergency department, and mean charges.

RESULTS

There was a relative reduction of 26.4% in the proportion of patients referred for knee radiography in the intervention group (77.6% vs 57.1 %; P<.001), but a relative reduction of only 1.3% in the control group (76.9% vs 75.9%; P=.60). These changes over time were significant when the intervention and control groups were compared (P<.001). The rule was found to have a sensitivity of 1.0 (95% confidence interval [CI], 0.94-1.0) for detecting 58 knee fractures. The K coefficient for interpretation of the rule was 0.91 (95% CI, 0.82-1.0). Compared with nonfracture patients who underwent radiography during the after-intervention period, those discharged without radiography spent less time in the emergency department (85.7 minutes vs 118.8 minutes) and incurred lower estimated total medical charges for physician visits and radiography (US $80 vs US $183).

CONCLUSIONS

Implementation of the Ottawa Knee Rule led to a decrease in use of knee radiography without patient dissatisfaction or missed fractures and was associated with reduced waiting times and costs. Widespread use of the rule could lead to important health care savings without jeopardizing patient care.

Mass gathering medical care: a twenty-five year review

INTRODUCTION

The purpose of this study was to critically review the provision of medical care at mass gatherings as described in 25 years of case reports. Specifically measured was the relationship between the size of a mass gathering and the frequency of patients seeking medical aid and the effects of certain event characteristics on this relationship.

METHODS

Data were obtained through a retrospective literature review. Medline and CINHAL computerized databases were searched for English language articles using several keywords: "mass gathering", "concert", "festival", "Olympics", "crowd"; "riot", "stadium", "sports", "games", "papal", and "football". Only articles containing complete information on the number of spectators, number of patients, type, location, and duration of the mass gathering were included in the primary analysis. As available, additional information was added including the described weather patterns, number of patients transported to a hospital, and number of patients suffering a cardiac arrest. Thirty-five of the approximately 100 articles reviewed, met these criteria.

RESULTS

A Spearman Rank Correlation Coefficient was calculated for number of spectators and patients and a significant relationship was identified (p = 0.0001). Mann-Whitney U-tests indicated that papal masses (p = 0.04), rock concerts (p = 0.005), hot climatic conditions (p = 0.03), and events held in the British Commonwealth (p = 0.03) had a significantly higher frequency of patient visits. Significantly more cardiac arrests occurred at papal masses (p = 0.04) and sporting events (p = 0.0002).

CONCLUSIONS

Type of event, country, weather, and the size of the mass gathering had a significant effect on the numbers of spectators seeking medical care. A uniform classification scheme is necessary for future prospective studies of mass gatherings.

Oxygen microelectrode response to oxygen pressures up to 15 ATA

Polarographic measurements of oxygen at high pressures were made at 21-22 degrees C with open-type Wood's metal microelectrodes with tip diameter about 5 mu. Although the sensitivity of the individual electrodes ranged from 3.1 x 10(-10) to 8.8 x 10(-12) amps/mm Hg of O2, the oxygen current was always a straight line function of Po2 from 21% O2 at ambient pressure (Po2 = 160 mm Hg) to 100% O2 at 200 psig (Po2 = 11,102 mm Hg). Compression to 200 psig with 100% nitrogen produced no significant change in microelectrode current, showing that the microelectrodes are insensitive to pressure alone.

Effect of intravenous sodium bicarbonate, disodium edetate (Na2EDTA), and hyperventilation on visual and oculomotor signs in multiple sclerosis

The effects of procedures believed to produce a decrease in serum ionized calcium were tested on visual and oculomotor function in nine multiple sclerosis (MS) patients. Transient improvement in scotomas, nystagmus, and oculomotor paresis occurred with intravenous infusions of NaHCO(3) or Na(2)EDTA. Hyperventilation was also tested for its effect on nystagmus and caused marked decreases in frequency. Control experiments with saline infusions did not produce any effect. The probable mechanism and site of action for these effects is discussed. This study demonstrates that certain signs and symptoms in MS can be altered favourably by changes in the internal chemical environment and offers a new approach to the search for a symptomatic therapy in MS.