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Biomedical subjects

A Bullinger

Publications and source records attributed to A Bullinger.

14 recordsLinked to original sources
PubMed2005

Modification of virtual reality combined with a mental task stimulates cortisol in volunteers.

Immersive, stereoscopic virtual reality (VR) systems provide a powerful multimedia tool for a laboratory simulation of distinct scenarios including stressful situations close to reality. Thus far, cortisol secretion as a neuroendocrine parameter of stress has not been evaluated within a VR paradigm. Ninety-four healthy subjects were subjected to a VR paradigm and a cognitive stress task. It was tested (a) if the modification of reality induced by dynamic VR as opposed to static VR can be regarded as a stressor and (b) if it can modify an additional cognitive stress response. In addition, the impact of gender on cortisol responses was assessed. A significant cortisol increase was observed only after the combined application of both conditions, but not after the dynamic VR or the cognitive stress alone. Cortisol reactivity was greater for men than for women. We conclude that dynamic VR does not affect cortisol secretion per se, but increases cortisol responses in a dual task paradigm. This provides the basis for the application of VR in neuroscientific research, which includes the assessment of hypothalamus-pituitary-adrenal axis regulation.

Adolescent↗
PubMed2003

[Treatment of acrophobia in a virtual environment].

Specific phobias are one of the most frequent mental health problems and can lead to years of personal suffering. The most effective treatment is exposure therapy. Our aim was to proof the feasibility and efficacy of virtual environments in treating acrophobia patients using a manually guided exposure therapy. Our pilot study was designed as a crossover intervention with a waiting list condition as a control group. After treatment, our results show that exposure in virtual environments is a feasible technique, can provoke anxiety, and leads to a therapeutic effect.

Adult↗
PubMed1999

Does visual sensitivity improve between 5 and 8 years? A study of automated visual field examination.

In 74 normal subjects (62 children aged 5-8 years and 12 adults), we tested the widely-held belief that visual sensitivity improves substantially during childhood. Maturation of the retino-striate pathways is generally invoked to account for age-related changes in visual sensitivity. We evaluated the extent to which attentional factors unduly emphasized the effect of age on the purely physiological mechanisms. After a specially-designed familiarization procedure, sensitivity was fully evaluated at two locations in the superior temporal field using a bracketing technique (Octopus 2000R). False-positive (FP) and false-negative (FN) catch-trials were interspersed with the sequence of stimuli. Analyses demonstrated that: (1) age affected sensitivity; and (2) the general level of attentiveness varied not only with age, but also among subjects in the same age group. We then estimated the extent to which improved visual sensitivity may reflect a concomitant evolution of vigilance. Firstly, controlled variance analyses indicated that factors for evaluating attentiveness (rate of FN responses, slope of the psychometric function at the median, and goodness of fit) were indeed much better predictors than age of the sensitivity measured. Secondly and more significantly, the grouping of subjects into homogeneous subgroups, on the basis of their attentional performance, showed that children as young as 5 years may have a visual sensitivity that is only marginally lower than that of adults.

Adult↗
PubMed1998

Automated visual field examination in children aged 5-8 years. Part I: Experimental validation of a testing procedure.

In 106 children aged 5-8 years, we determined how much training was needed to stabilize the response strategy prior to actual visual field assessment and we evaluated the reliability and acceptable duration of automated static perimetry (Octopus 2000R). A specially designed familiarization procedure was used to train the children to: (1) gaze at the center of the visual field while paying attention to light stimuli projected onto the periphery and (2) press the buzzer only when light stimuli were perceived. The subsequent examination phase consisted of 15 successive identical blocks of 27 trials (12 stimulus trials, 12 false-positive catch-trials, and three false-negative catch-trials), and was stopped before the end if signs of fatigue appeared. Age had a marked influence both on endurance (the number of blocks performed increased significantly) and on response reliability (false-positive responses decreased between 5- and 6-year-olds). The increase in false-negative responses toward the end indicates that examination is no longer reliable, and should be stopped. We concluded that most children as young as five can undergo examination by automated static perimetry. Changes regarding learning, stimulus intensity and testing procedure are suggested in order to adapt the examination to age, level of vigilance and health condition of the children.

Age Factors↗
PubMed1998

Automated visual field examination in children aged 5-8 years. Part II: Normative values.

We determined normative values for the visual sensitivity threshold in 118 children aged 5-8 years, using automated static perimetry (Octopus 2000R, program 32). In addition, 17 normal adults were tested. The children first underwent a familiarization procedure. One week later, quantitative examination was performed according to a specially designed schedule divided into three phases. For each of the 76 points tested, mean thresholds and standard deviations were calculated as a function of age. In contrast to previous studies, sensitivity difference between adults and children over the central 30 degrees of the visual field emerged only for the youngest age groups (5- and 6-year olds). Both the response rate in false-negative trials, and values of a within-subject threshold variability index, suggested that 5- and 6-year-olds' higher thresholds were inflated by non physiological factors, such as vigilance and cognitive processes. For these ages, the data reported here should therefore be considered as an approximation of the upper level of the thresholds. In contrast, our results for 7- and 8 year-old children provided reliable normative values for light sensitivity across the visual field.

Adult↗
PubMed1998

[Suicide over weekend leave--a seldom regarded risk factor].

OBJECTIVE: The study aims at differentiating qualitative and quantitative aspects of inpatient suicide on weekdays and during the weekend. METHOD: 51 consecutive suicides in a large psychiatric hospital were analysed retrospectively. RESULTS: 14 of 51 suicides occurred during weekend leave, most of them on a Saturday or Sunday. The rate of suicides in the hospital on a Saturday or Sunday is extremely low. CONCLUSION: Weekend leave from inpatient treatment must be considered as a risk factor of its own.

Adult↗
PubMed1997

[Assisted suicide after discharge from the psychiatric clinic].

Assisted suicide has become a topic often and controversally discussed in international literature. Psychiatry and mentally ill, however, have been neglected, probably because the question of competence of judgement and will are a major issue in this matter. Two cases are reported, one of a 60-year old man and a women of 87 years, who have committed suicide a few days after having been dismissed from stationary psychiatric care. The reason of admission had been a psychotic event with manifest AIDS-disease in the first, the public utterance of her wish to die with support of, the swiss "Help to Die" organization "Exit", in the latter. Ethics and means of preentive interventions in such cases are discussed.

AIDS Dementia Complex↗
PubMed1996

Feasibility of automated visual field examination in children between 5 and 8 years of age.

AIMS: To investigate how young children develop the ability to undergo a visual field evaluation using regular automated perimetry. METHODS: The study included 42 normal girls aged 5, 6, 7, and 8 years. Twelve locations in the 15 degrees eccentricity were tested in one eye, using an Octopus 2000R perimeter with a two level strategy. False positive and false negative catch trials were presented. The examination was performed three times in succession. Before the examination procedure, a specially designed programme was conducted for progressive familiarisation. RESULTS: During the familiarisation procedure, it was found that all of the 5-year-old children, seven of the 6-year-old children, and three of the 7-year-old children were unable to perform immediately, and correctly, the instructions given during the familiarisation phase; these children took from 30 seconds to 3 minutes to comply with the examiner's requests. With the exception of one 5-year-old child, all tested subjects completed the planned procedure. The mean proportion of false negative answers in catch trials was 1.6%. The mean proportion of false positive answers was 12.2%. The quadratic dependency on age suggested by the averages was not significant (F(3,116) = 0.88; p = 0.45). Detection stimulus improved with age, as shown by the fact that probability of perceiving dim stimulus increases significantly (F(3,116) = 12.68; p < 0.0001). CONCLUSION: Children did remarkably well regarding both the duration of the examination and the reliability of the answers. A preliminary familiarisation phase with a specially designed adaptation programme was found to be mandatory with children aged 7 or under. To our knowledge, this is the first time that such an investigation has been performed.

Age Factors↗
PubMed1995

[Automated static perimetry in the child: methodologic and practical problems].

PURPOSE: In a pediatric population, the use of computerized static perimetry is known as particularly difficult. The specific difficulties which may occur when testing young subjects are stability of fixation, ability to maintain concentration, resistance throughout the procedure, and reliability of the answers. It seems important to investigate and to develop appropriate strategies for the examination of children aged 8 years and younger according to their ability to undergo visual field evaluation using automated static perimetry. PATIENTS AND METHODS: Eighty normal children aged 5 to 8 years old were evaluated using an Octopus 2000R perimeter, with a one-level strategy. Adaptation of the procedure were included. RESULTS: The analysis of answers and false-positive catch-trials showed that children as young as five years old did remarkably well regarding both the duration of the examination and the reliability of answers. CONCLUSIONS: Automated static perimetry examination can provide reliable results in children as young as five years old once a familiarization procedure has been conducted and if the duration of examination does not exceed the child's capacity to remain task focused.

Child↗
PubMed1989

A device for the computer processed analysis of video frames.

This article briefly describes a system of analyzing movement sequences extracted from video images. The system uses an IBM-PC or compatible computer, equipped with a CGA screen and a mouse, and a videotape recorder and monitor. The coordinates of the points selected from the images with the mouse are stored in an ASCII-format file by a computer program. The principle behind this system is that it projects video images on a computer screen through a one-way mirror while avoiding parallax effects.

Journal Article↗
PubMed1979

[Animal experiments on the hemodynamics of prehepatic portal hypertension before and following various methods of portacaval anastomosis].

In 24 dogs (29 +/- 5,7 kg) general and intestinal hemodynamics were measured during acute prehepatic portal hypertension before and after mesentericocaval, splenorenal, and splenocaval (SCA) shunt. From the hemodynamic point of view the SCA is superior because of its complete venous decompression of the region of the spleen and cardia and a greater blood flow to the liver. Furthermore shunt flow, and consequently volume load imposed on the general circulation, is significantly smaller in SCA.

Animals↗
PubMed1977

[Method of registration and analysis of eye movements].

The aim of this article is to describe an apparatus registering eye movements, that alleviates the constraints that are usually necessary to control head movements. In a second part, the errors observed in gaze localisation by using the pupilar referential are analysed. Finally, means of increasing precision in the determination of visual fixation and facilitating the analysis of the registered images are proposed. These means comprise: (i) the use of an algorithm enabling the calculation of a correspondence grid of distortion for any one visual fixation, (ii) the use of a fixed standard dependent on the apparatus enbaling the permanent determination of the position of the head, (iii) the possibility of analysing the registered images in a semiautomatic way by means of a "writing tablet" and a computer of the PDP 8 series. Only four calibration points are necessary to determine all the useful parameters for the registering procedure and the analysis proposed.

Eye Movements↗