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Biomedical subjects

M B Andersen

Publications and source records attributed to M B Andersen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Psychosocial influences on central and peripheral vision and reaction time during demanding tasks.

We examined perceptual deficits hypothesized in a model of stress and injury relationships. An ophthalmologic perimeter was used to measure peripheral and central vision during baseline and demanding task situations for 201 intercollegiate athletes from 10 sports. We conducted analyses of covariance with the stress measures as dependent variables and their appropriate baseline measures as covariates. Performance under demanding tasks deteriorated significantly on all the perceptual variables. Individuals with high negative life events scores experienced greater peripheral narrowing and slower central vision reaction time during stress than did those with life events scores that were low. Men with low social support had more failures to detect cues, and men with high negative life events, low social support, and low coping skills had the lowest perceptual sensitivity. Women with high negative life events and low coping skills had more failures to detect cues. We discuss the findings in terms of how stress responsivity may influence injury risk through changes in perception and attention.

Adaptation, Psychological↗
PubMed1997

Student and supervisor perceptions of the quality of supervision in athletic training education.

OBJECTIVE: To assess the perceptions of the quality of athletic training supervision via the internship route to certification and the NATA-approved/CAAHEP programs. DESIGN AND SETTING: A questionnaire was mailed to head athletic trainers or NATA/CAAHEP program directors and athletic training students in 40 programs nationwide (stratified random sample). SUBJECTS: Head athletic trainers (20), NATA-approved or CAAHEP-accredited program directors (20), and athletic training students in those educational programs (149). MEASUREMENTS: The Athletic Training Supervisory Skills Inventory (ATSSI) was adapted from the Supervisory Evaluation Form (SEF) and athletic training literature. The ATSSI was reviewed by 30 certified athletic trainers, and their feedback was incorporated into the final version of the questionnaire. The ATSSI contains 46 questions that cover six major domains of athletic training supervisor behavior. RESULTS: Overall, there were no differences in how internship route supervisors and NATA/CAAHEP program directors rated their own supervisory skills. Also, there were few differences in how students in those two types of athletic training education programs rated their supervisors. CONCLUSIONS: This exploratory study's limitations included a one-time assessment approach and a small sample of supervisors. Future studies in supervision should take a longitudinal approach and include a larger sample size.

Journal Article↗
PubMed1997

Perceived uncertainty of outcome as a contributing factor in competitive state anxiety.

The Martens, Vealey, and Burton (1990) model of competitive anxiety contains perceived uncertainty, perceived importance, and competitive trait anxiety (A-trait) as key determinants affecting a person's perception of threat and competitive state anxiety (A-state). This experiment tested perceived uncertainty of outcome and A-trait influences on A-state. Club level golfers (N = 72) were assigned to either a low uncertainty condition (LU) or a high uncertainty (HU) condition. In this experiment participants were matched and competed for 12 golf balls in a modified chipping competition. Participants also completed the Competitive State Anxiety Inventory -2 and the Match Orientation Questionnaire (a measure of perceived uncertainty) prior to, and during breaks in the competition. Players alternated in taking four rounds of eight shots from a zone marked approximately 30 metres from the hole. A series of tests did not support the manipulation of uncertainty. This was probably due to likely losers and likely winners not experiencing similar levels of A-state, as Martens et al. assume. Recoding the uncertainty data to reflect levels of confidence, and entering confidence and A-trait into multiple regression equations resulted in these two variables accounting for between 15% and 23% of the A-state variance at different stages of the competition. Recommendations for future research, and possible revisions of the model in light of the present findings are discussed.

Adolescent↗
PubMed1996

Discrimination between artefacts and contractions in pressure signals from the gastrointestinal tract by pattern recognition method.

A pattern recognition algorithm has been developed to discriminate between artefacts and contractions in interdigestive motility recorded by a pressure catheter with four channels from the human duodenum. A learning and a test set, both containing natural and induced artefacts, such as respiration and body movement, are obtained from five volunteers. The event classes were phase I, II and III contractions of the interdigestive motility complex and artefacts from respiration, cough, calibration signals and movements. Length, area, amplitude, inter-event interval, up- and downstroke, and correlation to other pressure channels and to respiration, are applied to classify the events. The sensitivity of the computer scoring increases with the number of applied features. When all the features are applied, the sensitivity of the Bayes' classifier against the visually scored contractions and artefacts is 0.96 with a specificity of 0.69.

Adult↗
PubMed1994

Rabbit sphincter of Oddi and duodenal pressure and slow-wave activity. Effects of cholecystokinin.

BACKGROUND: The presence of sphincter of Oddi (SO) slow waves has been noted in earlier studies on the effect of cholecystokinin (CCK) on the SO, but a more thorough description of changes in SO slow-wave and pressure activity induced by CCK is needed. METHODS: The SO and duodenum in anaesthetized rabbits were prepared with perfused catheters and bipolar electrodes. Increasing, successive doses of CCK (1/32 to 1/1 Ivy Dog Units (IDU)/kg) were administered intravenously every 15th min. The digitized recordings were scored on a computer in control and stimulatory CCK sequences. RESULTS: CCK had a significantly stimulatory effect on SO and duodenum when estimated as area below pressure peaks (p < 0.001), but quantitatively, this effect did not differ in the two organs (p = 0.59). CCK significantly decreased SO slow-wave frequency (p < 0.05), whereas a similar trend in duodenal slow-wave frequency failed to reach statistical significance. Most pressure peaks recorded from the SO were associated with only one slow wave ('simple peak'), but the incidence of broad, irregular peaks belonging to more than one slow wave ('complex peaks') was significantly higher in CCK sequences (p < 0.02). Spectral analysis of SO pressure and slow-wave activity confirmed the dominating one-to-one relation between SO slow-wave and pressure peaks up to 1/4 IDU/kg, but also showed the disturbance caused by the increasing number of complex peaks generated by doses of at least 1/2 IDU/kg. CONCLUSIONS: CCK increases SO and duodenal activity equally. Up to a CCK dose of 1/4 IDU/kg the SO slow-wave regulatory mechanism is undisturbed, but higher doses lead to a fall in slow-wave frequency and qualitative changes in the relation between SO pressure and slow-wave activity.

Animals↗
PubMed1992

[Unconsciousness after ingestion of nail varnish].

Two males in their twenties lost consciousness after ingestion of 50 ml gamma-butyrolactone. Bradycardia was observed and treated during the first hours and they recovered after a few hours.

4-Butyrolactone↗
PubMed1992

Comparison of structure and activities of peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus.

Initial structural and kinetic data suggested that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus were similar. Therefore they were characterized more fully. The three peroxidases were purified to RZ 2.5 and showed immunochemical identity as well as an identical M(r) of 38,000, pI about 3.5 and similar amino acid compositions. The N-termini were blocked for amino acid sequencing. The peroxidases had similar retention volumes by anion-exchange and gel-filtration chromatography. All peroxidases showed multiple peaks by Concanavalin A-Sepharose chromatography. The Concanavalin A-Sepharose profiles were different and depended furthermore on a fermentation batch. Tryptic peptide maps were very similar except for one peptide. This peptide contained an N-linked glycan composed of varying ratios of glucosamine and mannose for the three peroxidases. Rate constants and their pH dependence were the same for the three peroxidases using guaiacol or iodide as reducing substrates. We conclude that peroxidases from Coprinus cinereus, Coprinus macrorhizus and Arthromyces ramosus are most likely identical in their amino acid sequences, but deviate in glycosylation which, apparently, has no influence on the reaction rates of the enzyme. We suggest, that the Coprinus fungi express one peroxidase only in contrast to the lignin-degrading white-rot Basidiomycetes, which produce multiple peroxidase isozymes.

Amino Acid Sequence↗
PubMed1992

Computer-aided analysis of gastrointestinal pressure recordings. Comparison with manual scoring.

The aim of the present study was to compare computer-based and visual/manual scoring of pressure recordings from the gastric antrum and duodenum. The computer system was based on three separate principles of recognition: moving average, tracking base line, and threshold filters. Computer scoring resulted in the detection of more contractions than visual/manual scoring, owing to inclusion of artefacts of duration and amplitude above the selected thresholds. Owing to its unreliability, visual/manual scoring led to inclusion of some contractions of below-borderline amplitude or duration. The median difference in the frequency of contractions was, however, 0 min-1. There was close agreement on amplitudes of contractions. As the differences between visual/manual analysis and computer-aided scoring by the present system are of an unimportant magnitude and as computer-based scoring is consistent, we conclude that computer-aided analysis is preferable to visual/manual analysis.

Duodenum↗
PubMed1991

Versatile software system for analysis of gastrointestinal pressure recordings.

A software package, MotAn, has been developed for off-line analysis of gastrointestinal pressure recordings. The program has been implemented in the Modula-2 language for use on IBM personal computers. The program includes capabilities for manual or automatic detection of contractions, calculation of frequency and intercontractile intervals, area of contractions, motility index, concordance and cross-correlation analysis for detection of artifact and for propagation analysis. The program has been applied on pressure recordings from the stomach and duodenum as well as on the rectum and the urinary bladder. Besides the basic part of the program, it is possible for the experienced programmer to add new blocks of object code for development of special analysis procedures.

Computer Graphics↗
PubMed1991

Radial analysis of duodenal motility recordings in humans.

To analyze radial variations in pressure recordings from the human duodenum, we used a catheter with six radially placed side holes with identical dynamic characteristics. Twenty-one hours of fasting pressure recordings were obtained in six volunteers. Computer-based cross-correlation analysis, event detection and counting, amplitude analysis, and concordance analysis were used for comparing the signals of the individual channels. Both the cross-correlation analysis and the counting of events showed radial asymmetry of contractile activity. This asymmetry was not related to any individual channel. The maximum difference between the individual channels was constantly between diametrically opposite spaced channels. The asymmetry was most pronounced during phase-I-like and phase-II-like activity of the migrating motility complex, whereas a much higher degree of cross-correlation and concordance was shown during phase-III-like activity. The results indicate that a greater in-depth analysis of pressure recordings from the small intestine--such as identification of individual events and differentiation between contractions and artefacts--requires that the recordings as a minimum comprise two diametrically placed side holes at each measurement level.

Adolescent↗
PubMed1990

Effects of life-event stress on anxiety and peripheral narrowing.

This study examined one of the mechanisms proposed to be behind the relationship between life stress and injury. Past researchers have identified a correlation between high life stress and athletic injury for contact and noncontact sports and for male and female athletes, but they did not investigate why athletes who experienced stress from life events were more prone to injury than those whose lives were low in stressful events. The authors tested the hypothesis that recreational athletes with high life-event stress would, when placed in a stressful, dual-task laboratory situation, experience greater narrowing of peripheral vision and state anxiety than recreational athletes with low life-event stress. ANOVA and regression results offered support for peripheral vision deficits as a potential mechanism in the life stress-injury relationship and very minimal support the effect of elevated state anxiety. The great variability in peripheral vision changes for the groups with high life stress suggests that, for certain subjects, some unmeasured variable may be buffering the adverse impact of high life-event stress. The authors recommend that future researchers examine potential moderating variables, such as coping resources, and assess the relative contributions of psychosocial variables, stress history variables, and mediating mechanisms in predicting actual injuries.

Adult↗
PubMed1989

Consistency in manual scoring analysis of gastrointestinal pressure recordings.

The aim of the present study was to evaluate the consistency in visual scoring and whether this could be the basis for computer analysis using pattern recognition techniques. We studied the consistency of visual scoring of pressure tracings from the upper gastrointestinal tract with regard to pressure wave identification. The aim was to make such an identification the golden standard for computerized analysis of pressure waves. Pressure recordings containing different phases of contraction activity were evaluated by five trained observers. The inter- and intra-observer agreement was highest in periods with high contraction activity (phase III), both of which were better than 90%. In periods with low contraction activity (phases I and II) this agreement was as low as 49%. The results indicate that forming a learning set for pattern recognition should only be based on visual scoring during phase-III activity.

Adult↗
PubMed1989

Computer analysis of manometric recordings. A study of overnight rectal activity in normal children.

To read and analyze manometric tracings from selected biological systems, a computer program was produced using low cost personal computer hardware. The program contains facilities for automatic scoring of contractions, intercontractile intervals (modality) and frequency analysis. This report concerns analysis of two overnight rectal motility recordings in 11 normal teenagers. After A/D conversion of data the developed software offers a set of options i.e. automatized scoring of contraction, detection of intervals between contractions and analytical tools such as histographic presentation of data, and presentation in the time domain. The A/D conversion time and computer analysis time for an 8 hour recording was 15 and 13 minutes, respectively. The analysis of frequency distribution overnight showed for the material as a whole 63% of no activity, 33% of 0-2 contractions x min-1 and 4% of more than 2 contractions x min-1. Modality analysis showed a peak between 15 and 25 seconds. Approximately 30% of the tracings showed accumulated intervals, which were multiples of the peak. No significant correlation was found between the first and second night of observation regarding the number of contractions and maximum frequency overnight. Significant correlation was found for the number of periods with high frequency activity between the two nights (p less than 0.05). Long-term pressure activity can be analyzed using the presented computer-aided method, providing a rapid and objective measurement of classical parameters and access to more in-depth analysis. This actual study of normal overnight rectal activity showed a large inter- and intra-individual variation.

Adolescent↗
PubMed1987

Influence of sex and gender roles on high school status systems.

Past research has indicated significant sex differences in determinants of male and female high school students' status as measured by how subjects would like to have been remembered from their high school years. In order to determine if remembrance preference is sex or gender role related, 671 subjects were administered the Bem Sex-Role Inventory (BSRI) and a questionnaire asking if they most wanted to be remembered from high school as a brilliant student, leader in activities, athletic star or most popular. Using both the median split and t-ratio procedures in scoring the BSRI, 206 subjects were selected because they were sex-typed (masculine males, feminine females), cross sex-typed (masculine females, feminine males), or androgynous (scoring high on both masculine and feminine traits). To find a model of best fit, the data were subjected to a log-linear analysis. The variables included were sex, gender role, and remembrance preference. Rather than sex being the influential factor, the model of best fit was a gender role by remembrance preference interaction. If subjects were masculine, they were more likely to choose athletic star than were feminine or androgynous subjects. Most popular and leader in activities were both more likely to be chosen by feminine and androgynous subjects. All groups chose brilliant student more often than any other category. It was concluded that some previously designated sex differences may instead be differences in gender role. Further research should address the distinction between the two.

Achievement↗