Within-subject Measures Research Articles

A cross-sectional study to compare two blood collection methods: direct venous puncture and peripheral venous catheter

ObjectivesTo demonstrate the equivalence between blood collection methods using direct venous puncture (DVP) and a peripheral venous catheter or cannula (PVC).Design and settingA cross-sectional study of simple crossover design with...

Few juvenile auditory perceptual skills correlate with adult performance.

Measures of human mental development suggest that behavioral skills displayed during early life can predict an individual's subsequent cognitive performance. Support for this draws from longitudinal studies that reveal compelling within-subject correlations during childhood. If this idea applies across the life span, then correlations in performance should persist into adulthood. Here, we address this prediction in juvenile and adult gerbils by evaluating within-subject measures of auditory learning and perception. Animals were trained and tested as juveniles on either an amplitude modulation (AM) or a frequency modulation (FM) detection task. Measures of learning and perception obtained from juveniles were then compared to similar measures obtained when each subject was tested in adulthood on either the same task or the untrained task. For animals trained and tested on the AM detection task as juveniles and adults, there was no correlation between juvenile and adult learning metrics, or perceptual sensitivity. For animals trained and tested on FM detection as juveniles, we observed a significant relationship to their adult performance. Juveniles that performed the best on FM detection were the poorest at AM detection, and the best at FM detection, when tested as adults. Thus, across-age correlations for sensory and cognitive measures, obtained during development and in adulthood, depend heavily on the specific type of developmental experience and the outcome measure.

Variation and variability in carotid-femoral pulse wave velocity

BackgroundThere are very limited data on the day-to-day variability and virtually no data on within-subject measurement variation of carotid-femoral pulse wave velocity (c-fPWV). Therefore, we conducted this study in healthy volunteers to measure both day-to-day variability and day-to-day within-subject measurement variation. MethodsC-fPWV values were measured in ten adult volunteers resting in supine position for at least 10 min using the SphygmoCor system {AtCor Medical Pty Ltd, West Ryde (Sydney), Australia} on two consecutive days. The data were captured for ten seconds from the right carotid and then right femoral arteries. ResultsThe average c-fPWV readings and the between-subject standard deviations (SD) was 7.43 ± 1.9 m/sec for day 1 and 6.93 ± 1.36 m/sec for day 2, which are statistically insignificant with a paired t-test (p = 0.197). However, the Pearson's correlation showed a coefficient of 0.8 (p value = 0.005). There was a statistically significant difference (p = 0.01) in the within-subject c-fPWV measurement variation, calculated as the mean of the SD comparing day 1 (0.74 ± 0.09 m/sec) and day 2 (0.53 ± 0.07 m/sec). The average MAP was 93.9 ± 2.3 mmHg for day 1 and 90.5 ± 1.7 mmHg for day 2, which were not statistically different (p = 0.1). ConclusionsThe c-fPWV readings were highly reproducible between the two days and the measurement variation in the within-subject c-fPWV is significantly lower on the second day. Our study highlights that day-to-day variability and within-subject measurement variation of c-fPWV, although present is not significant enough to influence the assessment of outcome measures of interventions that alter the arterial stiffness.

Reproducibility of Activation Maps for Longitudinal Studies of Visual Function by Functional Magnetic Resonance Imaging

To test the intra- and intersubject reproducibility of brain activation patterns that underlie visually guided saccades and word recognition in normally sighted subjects and patients with macular degeneration using functional magnetic resonance imaging (fMRI). Ten normally sighted subjects and five patients with macular degeneration were asked to perform two visually guided saccade tasks and two word-recognition tasks during fMRI with behavioral monitoring. The fMRI measurements were repeated three times at intervals of at least 4 weeks between sessions. The intrasubject reproducibility of the brain activation patterns was examined in a model-independent manner by comparing the distributions of activation across the frontal, parietal, temporal, and occipital brain lobes using Intraclass Correlation Coefficients (ICCs). Intersubject reproducibility was examined by repeated-measure ANOVA. Results. Control subjects showed overall higher intrasubject reproducibility of brain activation patterns (75% ICCs > 0.5) than that of patients with macular degeneration (56% ICCs > 0.5). The intrasubject reproducibility for the patients improved when the target location was fixed, as in the word-recognition tasks (75% ICCs > 0.5), compared with the visually saccade tasks (37% ICCs > 0.5). Intersubject variability of brain activation patterns was strikingly high for both the control and patient groups. The fMRI method can serve as a reliable within-subjects measure of brain activation that has potential for measuring longitudinal changes in brain networks associated with rehabilitation training. Striking intersubject variability reflected at the level of lobes of the brain among control subjects with similar behavioral performance, suggests individual analysis is necessary when implementing longitudinal brain activation studies.

Latent Inhibition in ADHD Adults On and Off Medication

Objective: To determine the effects of stimulant medication on performance of ADHD adults on a selective attention task that assesses the processing of irrelevant stimuli. Method: ADHD patients and matched controls were given two sessions of a two-stage visual search-latent inhibition (LI) task. In stage-1, they detected the location of a unique shape presented with homogeneous distractors. In stage- 2, target detection response time was examined as a function of the stage-1 experience with the target or distractor, or both, providing a within-subject measure of LI. In Session-1, the ADHD subjects were off their customary stimulant medication. In Session-2, they were on medication. Results: Off-medicated ADHD subjects exhibited similar LI to that of controls; medicated ADHD subjects exhibited less LI than controls. Group differences in LI were mediated by RTs to the previously task-irrelevant distractor stimulus. Conclusion: The attenuated LI of the on-medication ADHD group is attributable to drug action that reduces attentional resources allocated to distractors.

Varenicline increases in vivo striatal dopamine D2/3 receptor binding: an ultra-high-resolution pinhole [123I]IBZM SPECT study in rats

Ex vivo storage phosphor imaging rat studies reported increased brain dopamine D2/3 receptor (DRD2/3) availability following treatment with varenicline, a nicotinergic drug. However, ex vivo studies can only be performed using cross-sectional designs. Small-animal imaging offers the opportunity to perform serial assessments. We evaluated whether high-resolution pinhole single photon emission computed tomography (SPECT) imaging in rats was able to reproduce previous ex vivo findings. Rats were imaged for baseline striatal DRD2/3 availability using ultra-high-resolution pinhole SPECT (U-SPECT-II) and [123I]IBZM as a radiotracer, and randomized to varenicline (n=7; 2 mg/kg) or saline (n=7). Following 2 weeks of treatment, a second scan was acquired. Significantly increased striatal DRD2/3 availability was found following varenicline treatment compared to saline (time⁎treatment effect): posttreatment difference in binding potential between groups corrected for initial baseline differences was 2.039 (P=.022), indicating a large effect size (d=1.48). Ultra-high-resolution pinhole SPECT can be used to assess varenicline-induced changes in DRD2/3 availability in small laboratory animals over time. Future small-animal studies should include imaging techniques to enable repeated within-subjects measurements and reduce the amount of animals.

The Role of Risk Aversion in Non-Conscious Decision Making

To what extent can people choose advantageously without knowing why they are making those choices? This hotly debated question has capitalized on the Iowa Gambling Task (IGT), in which people often learn to choose advantageously without appearing to know why. However, because the IGT is unconstrained in many respects, this finding remains debated and other interpretations are possible (e.g., risk aversion, ambiguity aversion, limits of working memory, or insensitivity to reward/punishment can explain the finding of the IGT). Here we devised an improved variant of the IGT in which the deck-payoff contingency switches after subjects repeatedly choose from a good deck, offering the statistical power of repeated within-subject measures based on learning the reward contingencies associated with each deck. We found that participants exhibited low confidence in their choices, as probed with post-decision wagering, despite high accuracy in selecting advantageous decks in the task, which is putative evidence for non-conscious decision making. However, such a behavioral dissociation could also be explained by risk aversion, a tendency to avoid risky decisions under uncertainty. By explicitly measuring risk aversion for each individual, we predicted subjects’ post-decision wagering using Bayesian modeling. We found that risk aversion indeed does play a role, but that it did not explain the entire effect. Moreover, independently measured risk aversion was uncorrelated with risk aversion exhibited during our version of the IGT, raising the possibility that the latter risk aversion may be non-conscious. Our findings support the idea that people can make optimal choices without being fully aware of the basis of their decision. We suggest that non-conscious decision making may be mediated by emotional feelings of risk that are based on mechanisms distinct from those that support cognitive assessment of risk.

Adaptation of the BKB-SIN Test for Use as a Pediatric Aided Outcome Measure

There is a need for objective pediatric hearing aid outcome measurement and thus a need for the evaluation of outcome measures. We explored a commercially available pediatric sentence-in-noise measure adapted for use as an aided outcome measure. The purposes of the current study were (1) to administer an adapted BKB-SIN (Bamford-Kowal-Bench Speech-in-Noise test) to adults and children who have normal hearing and children who use hearing aids and (2) to evaluate the utility of this adapted BKB-SIN as an aided, within-subjects outcome measure for amplification strategies. We used a mixed within and between groups design to evaluate speech recognition in noise for the three groups of participants. The children who use hearing aids were tested under the omnidirectional, directional, and digital noise reduction (DNR) conditions. Results from each group were compared to each other, and we compared results of each aided condition for the children who use hearing aids to evaluate the test utility as an aided outcome measure. The study sample consisted of 14 adults with normal hearing (aged 22-28 yr) and 15 children with normal hearing (aged 6-18 yr), recruited through word of mouth, and 14 children who use hearing aids (aged 9-16 yr) recruited from local audiology clinics. List pairs of the BKB-SIN test were presented at 50 dB HL as follows: four list pairs to each participant with normal hearing, four list pairs in the omnidirectional condition, and two list pairs in the directional and DNR conditions. Children who use hearing aids were fitted bilaterally with laboratory devices and completed the BKB-SIN test aided. Data were plotted as mean percent of key words correct at each signal-to-noise ratio (SNR). Further, we conducted an analysis of variance for group differences and within-groups for the three aided conditions. Adult participants outperformed children with normal hearing, who outperformed the children who use hearing aids. SNR-50 (signal-to-noise ratio at which listener can obtain a speech recognition score of 50% correct) scores demonstrated reliability of the adapted test implementation. The BKB-SIN test measured significant differences in performance for omnidirectional versus directional microphone conditions but not between omnidirectional and DNR conditions. We conclude that the adapted implementation of the BKB-SIN test can be administered reliably and feasibly. Further study is warranted to develop norms for the adapted implementation as well as to determine if an adapted implementation can be sensitive to age effects. Until such norms are developed, clinicians should refrain from comparing results from the adapted test to the test manual norms and should instead use the adapted implementation as a within-subject measure.

Evaluation of a Rotary Laser Body Scanner for Body Volume and Fat Assessment

This paper reports the evaluation tests on the reliability and validity of a 3-dimensional (3D) laser body scanner for estimation of body volume and % fat. Repeated measures of body imaging were performed for reproducibility analysis. Validity of the instrument was assessed by comparison of measures of body volume by imaging to hydrodensitometry, and body fat was compared to hydrodensitometry and dual energy X-ray absorptiometry. Reproducibility analysis showed little difference between within-subjects measurements of volume (ICC ≥ 0.99, p < 0.01). Body volume estimations by laser body scanner and hydrodensitometry were strongly related (r = 0.99, p < 0.01), and agreement was high (ICC = 0.99, p < 0.01). Measurements of % body fat also agreed strongly with each other between methods (ICC = 0.86, p < 0.01), and mean % fat estimates by body imaging did not differ from criterion methods (p > 0.05). These findings indicate that the 3D laser body scanner is a reliable and valid technique for the estimation of body volume. Furthermore, body imaging is an accurate measure of body fat, as compared to dual energy X-ray absorptiometry. This new instrument is promising as a quick, simple to use, and inexpensive method of body composition analysis.

Using within-subject multivariate pattern-classification to understand lifespan-age differences in oscillatory mechanisms of working memory selection and maintenance

Event Abstract Back to Event Using within-subject multivariate pattern-classification to understand lifespan-age differences in oscillatory mechanisms of working memory selection and maintenance Markus Werkle-Bergner1*, Julian Karch1, Myriam C. Sander1, Timo VonOertzen2 and Ulman Lindenberger1 1 Max Planck Institute for Human Development, Germany 2 University of Virginia, United States Working memory (WM) processes, related to information selection and maintenance, develop gradually during childhood and show senescent decline in late adulthood. How age-associated changes in WM processes are reflected in neuronal mechanisms related to alpha (~8-14 Hz) and theta (~4-8 Hz) oscillations is still an open question. In part, the difficulty to understand age- differences in brain oscillatory mechanisms supporting WM can be attributed to the large intra-group heterogeneity at the extreme ends of the lifespan, i.e., in children and older adults. To accommodate the large inter-individual variability and to derive age-fair measures across participants we suggest to rely on reliable within-subject measures for the effects of interest as the basis for age-group comparisons. In the present study, children, younger, and older adults performed a cued change-detection WM task, while the amount of to be maintained information was varied. Multivariate pattern classification algorithms were adapted to estimate time-varying spatial filters maximally sensitive for differences in oscillatory activity on a within-subject trial-to-trial level. Filters were trained to predict: a) the focus of attention (left vs. right) or b) the amount of maintained information. Cross-validation was applied to select the most reliable filters sensitive for the contrast of interest. The accompanying power/phase time-courses were extracted for age-group comparisons across subjects. Results suggest commonalities in spatial patterns of oscillatory activity in the presence of differences in the timing of neuronal interactions. Overall, we demonstrate that within-subject pattern classification is a promising tool to derive valid lifespan age-comparisons in light of large within-group heterogeneity. Keywords: development, memory and learning Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neural Bases of Memory and Learning Citation: Werkle-Bergner M, Karch J, Sander MC, VonOertzen T and Lindenberger U (2011). Using within-subject multivariate pattern-classification to understand lifespan-age differences in oscillatory mechanisms of working memory selection and maintenance. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00223 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Mr. Markus Werkle-Bergner, Max Planck Institute for Human Development, Berlin, Germany, werkle@mpib-berlin.mpg.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Markus Werkle-Bergner Julian Karch Myriam C Sander Timo VonOertzen Ulman Lindenberger Google Markus Werkle-Bergner Julian Karch Myriam C Sander Timo VonOertzen Ulman Lindenberger Google Scholar Markus Werkle-Bergner Julian Karch Myriam C Sander Timo VonOertzen Ulman Lindenberger PubMed Markus Werkle-Bergner Julian Karch Myriam C Sander Timo VonOertzen Ulman Lindenberger Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Optical Imaging: A New Window to the Adult Brain

Noninvasive optical imaging is an emerging method of functional neuroimaging that has major advantages that make it particularly suited to both basic and clinical neuroscience research as well as to clinical practice.2–7 It has great promise for contributing to neuropsychiatry.2 The required equipment is compact and portable, it is relatively easy to use, and the method is relatively tolerant of subject movement. Studies can be performed in almost any location including at the bedside and in natural settings. Patients who are not good candidates for more traditional functional imaging methods (e.g., functional MRI [fMRI] and positron emission tomography [PET]) often do well with optical imaging, as it does not require absolute stillness or confinement and has no associated loud noises. It is also safe to use in the presence of metal (e.g., plates, pins, pacemakers), an important consideration for some populations of interest. It has much faster time resolution than most other functional imaging techniques and can easily provide repeated within-subject measures. Other major advantages are low cost and high safety. Like surface electroencephalography (EEG), optical imaging captures activation-related changes only from the cerebral cortex. Historically, the major disadvantages of optical imaging have been its lower spatial resolution and smaller regions of coverage, areas of major improvement over the last decade. Use of optical imaging for monitoring of cerebral state in high-risk situations (e.g., neurosurgery, intensive care unit), while an important clinical application, is outside the scope of this review.8–10

Bayesian Nonparametric Regression Analysis of Data with Random Effects Covariates from Longitudinal Measurements

We consider nonparametric regression analysis in a generalized linear model (GLM) framework for data with covariates that are the subject-specific random effects of longitudinal measurements. The usual assumption that the effects of the longitudinal covariate processes are linear in the GLM may be unrealistic and if this happens it can cast doubt on the inference of observed covariate effects. Allowing the regression functions to be unknown, we propose to apply Bayesian nonparametric methods including cubic smoothing splines or P-splines for the possible nonlinearity and use an additive model in this complex setting. To improve computational efficiency, we propose the use of data-augmentation schemes. The approach allows flexible covariance structures for the random effects and within-subject measurement errors of the longitudinal processes. The posterior model space is explored through a Markov chain Monte Carlo (MCMC) sampler. The proposed methods are illustrated and compared to other approaches, the "naive" approach and the regression calibration, via simulations and by an application that investigates the relationship between obesity in adulthood and childhood growth curves.

Quantification of Rimonabant (SR 141716A) in Monkey Plasma Using HPLC with UV Detection

Using an isocratic high-performance liquid chromatography (HPLC) system and UV detection, a simple and precise analytical procedure was developed to quantify levels of the CB(1) receptor antagonist rimonabant in the plasma of rhesus monkeys. Rimonabant was extracted from plasma samples into 5% isopropanol in hexane. After separation, the isopropanol-hexane fractions were dried to residue, redissolved in mobile phase, and then injected into the HPLC. The HPLC system included an acetonitrile-phosphate buffer (62:38, v/v) mobile phase (pH 6.7), flow rate of 1.5 mL/min, C(18) column (4.6 mm i.d. x 150 mm length, 5 microm), and UV detection at 280 nm. Retention times for rimonabant and doxepin (internal standard) were 9.9 and 2.4 min, respectively. The regression of the spiked calibrator curve was linear from 60 to 4000 ng/mL (r(2) = 0.996). The lower limit of quantification was 60 ng/mL, and recovery was 83.6%. Rimonabant was stable in stock solutions and monkey plasma across a range of temperatures and concentrations. To demonstrate utility, plasma rimonabant was measured in six rhesus monkeys at 60 and 240 min after intramuscular administration of 1 mg/kg rimonabant. Rimonabant levels ranged from 175 to 1290 ng/mL. The analytical assay described here provides a simple and accurate procedure for multiple within-subject measurements of the CB(1) antagonist rimonabant.

Validation of a 3-Dimensional Laser Body Scanner for Assessment of Waist and Hip Circumference

Objectives: To evaluate the reliability and validity of a 3-dimensional laser body scanner for estimation of waist and hip circumferences and waist:hip ratio.Methods: Seventy women were evaluated for waist and hip circumference and waist∶hip ratio via laser scanner and tape measure. In a subset of 34 participants, 8 repeated measures of laser scanning were performed for reproducibility analysis. Validity of the instrument was assessed by regression and Bland-Altman comparison of measures of waist and hip circumferences and waist∶hip ratio to tape measure.Results: Reproducibility analysis showed little difference between within-subjects measurements of circumferences (intraclass correlation coefficient ≥0.992, p < 0.01). Evaluation of waist and hip circumferences measured by body scanning did not differ significantly from tape measure (p > 0.05). Bland-Altman analysis showed no bias between laser scanning and tape measure.Conclusion: These findings indicate that the 3-dimensional laser body scanner is a reliable and valid technique for the estimation of waist and hip circumferences as compared with tape measure. This instrument is promising as a quick and simple method of body circumference analysis.

Effects of a Combined Physical Activity and Dietary Change Intervention on Weight Loss in Minority Breast Cancer Survivors.

Abstract Background: Hispanic and black women with breast cancer have poorer survival and are more likely to be obese and sedentary than non-Hispanic whites. Regular physical activity, high intake of fruits and vegetables, and lean body mass may improve survival. We report the initial results of a randomized wait-list controlled pilot study to test the effects of 6 months of the community-based Curves® exercise and nutrition program on weight loss among minority BC survivors.Methods: Hispanic/black women with stage 0-IIIa breast cancer who were ≥6 months post-treatment, sedentary and had a BMI≥25kg/m2 were enrolled. Eligible participants were randomized to the Immediate Arm (IA): 6 months of the Curves® exercise and dietary change weight loss program, followed by 6 months of observation; or the Delayed Arm (DA): 6 months of a waitlist control period, followed by 6 months of the Curves® program. The intervention entailed recommending exercise 5 times/wk using the 30-minute Curves® circuit-based exercise program and attending a series of 6 weekly nutrition sessions that promoted a high-vegetable/low-fat diet. All study materials were available in Spanish and English. Participants underwent clinic visits at baseline, 3, 6, 9, and 12 months and were followed with monthly telephone calls during the intervention. Month 6 results are reported here.Results: Forty-two women enrolled in the study (IA, n=22; DA, n=20). Baseline characteristics: mean (±SD) age, 50.7 (±8.9) years; 78.6% Hispanic/21.4% black; breast cancer stage, stage 0 9.5%, stage I 42.9%, stage II 33.3%, stage III 14.2%; mean body mass index (BMI), 33.2 (±5.9) kg/m2; mean % body fat as measured by DEXA, 41.6 (±4.9) %; and mean VO2 max, 18.4 (±3.6). Six month data were collected from 39 women; 2 women were removed from the study due to medical conditions (1 recurrent disease, 1 previously undiagnosed cardiac condition) and 1 women dropped from the study due to being too busy. In the IA, the average number of exercise sessions attended over the 6 month period was 1.1(±0.8) per week (range: 0.04 to 2.9/wk), and all participants attended all 6 nutrition classes either in-person or via phone make-up sessions. After 6 months, women in the IA lost an average of 2.7 (±3.2) kg (range: loss of 9.9 kg to gain of 1.7 kg), had a decrease in percent body fat of 1.5 (±1.5)% (range: loss of 5.9% to gain of 0.2%), and a decrease in VO2max of 1.0 (±3.4) ml/kg/min (range: decrease of 8.6 ml/kg/min to increase of 2.5 ml/kg/min) (within-subject measures p&amp;lt;0.05 for change in weight and percent body fat; all between-arm measures p&amp;gt;0.05). Twelve month data collection will be completed in July 2009 and will be presented at the conference.Conclusions: This 6 month pilot physical activity and dietary change intervention resulted in decreased in body weight and percent body fat among Hispanic and black BC survivors, although this decline was not significantly different than the wait-list control group. Though adherence to the exercise intervention was less than the targeted 5 exercise sessions per week, those that did adhere lost up to 9.9 kg. Further research on barriers to participation, optimal dose, and duration are necessary for future intervention trials. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1038.

Interactive effects of ethanol and nicotine on learning, anxiety, and locomotion in C57BL/6 mice in the plus-maze discriminative avoidance task

Introduction Alcohol and nicotine both alter learning, locomotion, and anxiety, yet no study has directly examined the interactive effects of these drugs across these behaviors within subjects. Such a comparison would determine if the drugs produce independent effects on each behavior. The plus-maze discriminative avoidance task (PMDAT) allows within-subject measurement of these behaviors. Methods For training, each mouse explored the elevated plus-maze for 5 min and each time a mouse entered the aversive enclosed arm, a light and white noise were turned on. For testing, each mouse was returned to the center of the maze and, for 3 min, the time in each arm or in the center area was recorded. No cues were turned on during testing. The effects of ethanol (0.6–2.6 g/kg 15 min before training) and nicotine (0.045–0.18 mg/kg 5 min before training), alone or in combination, on behavior were examined. Results Ethanol dose-dependently decreased anxiety, increased locomotion, and decreased learning but different doses altered each behavior. Nicotine dose-dependently increased anxiety and locomotion and decreased learning but different doses altered each behavior. Nicotine (0.09 mg/kg) reversed ethanol-associated changes in learning (1.0 and 1.4 g/kg), locomotion (1.4 g/kg), and anxiety (1.4 g/kg). Conclusions The effects of nicotine or ethanol on learning occurred at different doses than those that altered anxiety or locomotion, suggesting that the drug effects on learning are independent of the effects on anxiety and locomotion. With combined administration, nicotine reduced ethanol-associated deficits in learning and changes in anxiety and locomotion.

The eye-complaint questionnaire in a visual display unit work environment: Internal consistency and test–retest reliability

The internal consistency and test–retest reliability of a 10-item eye-complaint questionnaire (ECQ) were examined within a sample of office workers. Repeated within-subjects measures were performed within a single day and over intervals of 1 and 7 d. Questionnaires were completed by 96 workers (70% female, mean age 36.4 years) who perform more than 4 h of visual display unit work each day. The internal consistency of the ECQ was high (α = 0.801). Although test–retest reliability was low within a single day (morning and afternoon) (intra-class correlation coefficient (ICC) = 0.68, 95% CI 0.38, 0.82), it was good between two morning measurements over a 1-d interval (ICC = 0.91 95% CI 0.87, 0.94) and between morning measurements with a 7-d interval (ICC = 0.87, 95% CI 0.81, 0.92). The ICC between afternoon measurements over a 1-week interval was moderate (ICC = 0.78, 95% CI 0.66, 0.85). This questionnaire is a reliable and consistent instrument for easily assessing eye complaints in office work. The timing of the measurements must be kept in consideration since measurements are confounded by exposures over the day.

Effects of ethanol and caffeine on behavior in C57BL/6 mice in the plus-maze discriminative avoidance task.

Caffeine is frequently consumed concurrent to or immediately following ethanol consumption. Identifying how caffeine and ethanol interact to modulate behavior is essential to understanding the co-use of these drugs. The plus-maze discriminative avoidance task (PMDAT) allows within-subject measurement of learning, anxiety, and locomotion. For training, each mouse was placed in the center of the plus-maze for 5 min, and each time that the mouse entered the aversive enclosed arm, a light and white noise were turned on. At testing, each mouse was returned to the center of the maze for 3 min. No cues were turned on during testing. Ethanol (1.0-1.4 g/kg) dose-dependently decreased anxiety and learning, and increased locomotion. Caffeine (5.0-40.0 mg/kg) dose-dependently increased anxiety and decreased locomotion and learning. Caffeine failed to reverse ethanol-induced learning deficits. However, 1.4 g/kg ethanol blocked the anxiogenic effect of caffeine. Although caffeine and ethanol interact to modulate behavior in the PMDAT, caffeine does not reverse ethanol-induced learning deficits. Ethanol-induced anxiolysis may contribute to alcohol consumption, while ethanol's blockade of caffeine-induced anxiogenesis may contribute to co-use.

Exhaled nitric oxide measurements: Correction equation to compare hand-held device to stationary analyzer

Exhaled nitric oxide (FE(NO)) is a reliable non-invasive marker of airway inflammation. In 2003 FE(NO) chemiluminescence analyzer (NIOX; Aerocrine AB, Solna, Sweden) was approved by U.S. Food and Drug Administration for monitoring asthma therapy. Recently, the same company developed a portable device using electrochemical sensors (NIOX-MINO; Aerocrine AB). The aim of our study was to compare NIOX-MINO FE(NO) values to those obtained by NIOX and to calculate a correction equation. Two adequate measurements obtained by NIOX and NIOX-MINO were recorded in 32 subjects (16 females, mean age 41 years). FE(NO) values measured by NIOX-MINO were systematically higher than those obtained by NIOX (47.1ppb, IC 95% 35.2-59.1 and 36.9ppb, IC 95% 25.0-49.0, respectively). There was a significant correlation (r=0.998, p<0.001) between FE(NO) measured by the two analyzers and the following conversion equation was calculated as: FE(NO(NIOX))=-1.656(SE=0.61)+0.808(SE=0.009)x FE(NO(NIOX-MINO)) DISCUSSION: FE(NO) values measured by the portable nitric oxide analyzer are reliable and strongly correlated with values obtained by the standard stationary device, with a systematic difference observed between the two instruments' values that can be described by the conversion equation we provided. This equation will help clinicians and researchers to compare data obtainable by the two analyzers.

Longitudinal MRI evaluations of human global cortical thickness over minutes to weeks

Magnetic resonance imaging (MRI) was used to evaluate within-subject variability in global mean cortical thickness over test-retest intervals of minutes-weeks in five healthy adults. Within-subject measures of global mean thickness were consistent over these intervals. Test-retest assessments of absolute thickness differences and percent thickness differences indicated variations of, respectively, < or =0.05-0.06 mm and < or =+/-1.9-2.3%. There have been few evaluations of normal within-subject variations in cortical thickness. The present results suggest that within-subject variability in global mean cortical thickness can be low over test-retest intervals of minutes-weeks, and that longitudinal scans can establish useful baseline estimates of variability from which to assess changes due to injury, disease, or other experiences.