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Biomedical subjects

E Olbrich

Publications and source records attributed to E Olbrich.

At least 19 recordsLinked to original sources
PubMed2005

[Effects of distress and coping on quality of life in HIV-positive patients: results of a longitudinal study].

Preserving health-related quality of life (QOL) is an important approach with HIV-positive patients. In a longitudinal study over 3 years, with three measurements each 18 months, we examined 56 of these patients for the influence of distress and coping (assessed by interviews) on physical, cognitive-emotional, and social QOL (using the SEL questionnaire). The patients were 32.9 years old on average, with 28.3 months since diagnosis. Seventy percent were male, 82% asymptomatic, 14% with ARC, and 4% with AIDS. Forty-five percent had been infected by homosexual intercourse, 14% by heterosexual intercourse, and 41% by iv drug abuse. The patients reported significantly worse physical and cognitive-emotional QOL than healthy subjects. Those HIV-positive persons with great distress showed significantly lower QOL scores. Multiple analyses of regression showed evasive-regressive coping at the T1, T2, and T3 levels as negative predictors, vs active, problem-focused coping as a positive predictor for nearly all QOL parameters at T3. HIV-positive patients with ARC or AIDS reported more physical complaints and lower physical QOL than asymptomatic persons. Physicians should suggest psychosocial support to patients with poor QOL scores.

Adaptation, Psychological↗
PubMed2005

Analysis of oscillatory patterns in the human sleep EEG using a novel detection algorithm.

The different brain states during sleep are characterized by the occurrence of distinct oscillatory patterns such as spindles or delta waves. Using a new algorithm to detect oscillatory events in the electroencephalogram (EEG), we studied their properties and changes throughout the night. The present approach was based on the idea that the EEG may be described as a superposition of stochastically driven harmonic oscillators with damping and frequency varying in time. This idea was implemented by fitting autoregressive models to the EEG data. Oscillatory events were detected, whenever the damping of one or more frequencies was below a predefined threshold. Sleep EEG data of eight healthy young males were analyzed (four nights per subject). Oscillatory events occurred mainly in three frequency ranges, which correspond roughly to the classically defined delta (0-4.5 Hz), alpha (8-11.5 Hz) and sigma (11.5-16 Hz) bands. Their incidence showed small intra- but large inter-individual differences, in particular with respect to alpha events. The incidence and frequency of the events was characteristic for sleep stages and non-rapid eye movement (REM)-REM sleep cycles. The mean event frequency of delta and sigma (spindle) events decreased with the deepening of sleep. It was higher in the second half of the night compared with the first one for delta, alpha and sigma oscillations. The algorithm provides a general framework to detect and characterize oscillatory patterns in the EEG and similar signals.

Algorithms↗
PubMed2003

Dimensional complexity and spectral properties of the human sleep EEG. Electroencephalograms.

OBJECTIVE: The relevance of the dimensional complexity (DC) for the analysis of sleep EEG data is investigated and compared to linear measures. METHODS: We calculated DC of artifact-free 1 min segments of all-night sleep EEG recordings of 4 healthy young subjects. Non-linearity was tested by comparing with DC values of surrogate data. Linear properties of the segments were characterized by estimating the self-similarity exponent alpha based on the detrended fluctuation analysis which quantifies the persistence of the signal and by calculating spectral power in the delta, theta, alpha and sigma bands, respectively. RESULTS: We found weak nonlinear signatures in all sleep stages, but most pronounced in sleep stage 2. Strong correlations between DC and linear measures were established for the self-similarity exponent alpha and delta power, respectively. CONCLUSIONS: The dimensional complexity of the sleep EEG is influenced by both linear and nonlinear features. It cannot be directly interpreted as a nonlinear synchronization measure of brain activity, but yields valuable information when combined with the analysis of linear measures.

Adult↗
PubMed2001

Reconstruction of the parameter spaces of dynamical systems.

Parameter variations in the equations of motion of dynamical systems are identified by time series analysis. The information contained in time series data is transformed and compressed to feature vectors. The space of feature vectors is an embedding for the unobserved parameters of the system. We show that the smooth variation of d system parameters can lead to paths of feature vectors on smooth d-dimensional manifolds in feature space, provided the latter is high-dimensional enough. The number of varying parameters and the nature of their variation can thus be identified. The method is illustrated using numerically generated data and experimental data from electromotors. Complications arising from bifurcations in deterministic dynamical systems are shown to disappear for slightly noisy systems.

Journal Article↗
PubMed2000

Local estimates for entropy densities in coupled map lattices

We present a method to derive an upper bound for the entropy density of coupled map lattices with local interactions from local observations. To do this, we use an embedding technique that is a combination of time delay and spatial embedding. This embedding allows us to identify the local character of the equations of motion. Based on this method we present an approximate estimate of the entropy density by the correlation integral.

Journal Article↗
PubMed2000

Chaos or noise: difficulties of a distinction

In experiments, the dynamical behavior of systems is reflected in time series. Due to the finiteness of the observational data set, it is not possible to reconstruct the invariant measure up to an arbitrarily fine resolution and an arbitrarily high embedding dimension. These restrictions limit our ability to distinguish between signals generated by different systems, such as regular, chaotic, or stochastic ones, when analyzed from a time series point of view. We propose to classify the signal behavior, without referring to any specific model, as stochastic or deterministic on a certain scale of the resolution epsilon, according to the dependence of the (epsilon,tau) entropy, h(epsilon, tau), and the finite size Lyapunov exponent lambda(epsilon) on epsilon.

Journal Article↗
PubMed1997

Longitudinal development of distress, coping and quality of life in HIV-positive persons.

BACKGROUND: Longitudinal study on burdens, quality of life and coping strategies of HIV-positive persons to identify patterns of successful adaptation to the demands of the infection. METHODS: In a semiprospective multimodal approach, 61 HIV-positive persons in all stages of the infection attending an HIV ambulatorium were assessed by inventories (3 times) and by a half-standardized interview (baseline T1 focussing on first reactions after diagnosis, follow-up T3 1.5 years later). Subjects had a mean age of 35.3 years and 69% were male. Forty-four percent were infected via homosexual intercourse, 46% via intravenous needle sharing and 10% via heterosexual intercourse or an unknown source. RESULTS: Global, psychic and familial distress decreased significantly from the first period after the diagnosis of HIV to the third time of measurement, while somatic complaints increased. Most test persons were able to deal effectively with the demands of the infection and showed a great degree of flexibility in their use of cognitive-actional and emotional-palliative strategies; they achieved a high quality of life. In contrast, highly distressed individuals, mainly drug users, tended to cope in an evasive-regressive way and reported a low quality of life. Correlations between ineffective coping strategies and low quality of life were found to be significant. CONCLUSIONS: After an initial phase of sorrow and lack of orientation regarding their future life, most HIV-positive persons deal effectively with the demands of the HIV infection and report a good quality of life. In contrast, HIV-positive persons with a high degree of distress and an evasive-regressive coping pattern need professional support, such as psychotherapy.

Adaptation, Psychological↗
PubMed1994

[Social support by professional personnel during inpatient treatment of cancer patients. "Chronic disease and coping with illness" research project].

We examined 63 in-patients in a medical hospital with a semi-structured and video-taped interview about the professional social support they had received. Patients were quite satisfied with physicians' and nurses' support, still more than one third of them had missed appraisal support from physicians. We found evidence that older, more ill and female patients perceived more professional social support was given. With the help of a hierarchical cluster analysis it was shown that the importance of professional social support depended remarkably on individual factors as identity or partner relation.

Adaptation, Psychological↗
PubMed1993

[The quality of life of tumor patients as a multidimensional concept].

An important aim of supportive care for cancer patients (pts) is the maintenance or improvement of their life quality. Therefore it is interesting to measure pts' LQ while testing new cytotoxic drugs or palliative therapy like artificial nutrition. A short questionnaire also is helpful in order to inform physicians and psychooncologists about pts' needs for psychosocial intervention. Based on coping-research, gerontology and well-being-psychology we have developed a 69-item-questionnaire "Scales for Measuring LQ" with good test-statistics. This instrument emphasizes pts' life experiences and subjective appraisal of objective life conditions. Basic state, internalized life experiences and life orientations in a sample of 179 pts with chemo- or radiotherapy are more important for LQ than objective symptoms, subjectively perceived physical condition and mood. The surprisingly high LQ scores in cancer pts can best be explained by their reduced aspiration levels. Correlations with emotional and belonging support obtained from the partner or confidant are significant. Social support is before all related to our pts' positive life experiences (.68; .59) and to their life satisfaction (.58; .47).

Adolescent↗
PubMed1982

The effect of alinidine (St 567) on emotionally induced tachycardia in man.

Experiments were performed in a randomized double-blind cross-over study in 6 healthy volunteers to answer the question if alinidine, a new analogue of clonidine with a bradycardic effect directly on the sinus node, would have an effect on an emotionally-induced tachycardia. Alinidine 40 mg orally significantly (1%) reduced the tachycardia and the concomitant rise in diastolic blood pressure during the stress of performing a mental task. Forearm blood flow and the efficiency (total score in the mental task) remained unchanged by alinidine.

Adult↗
PubMed1982

Pregnancy rates during long-term use of copper IUDs.

990 cases of women using standard copper IUDs (Cu 7; Cu T; Multiload) up to a maximum period of 8 years have been analyzed statistically. The long-term use effectiveness was evaluated mainly by using statistical methods (life table). Pregnancy rates decreased during the whole period of observation but more evidently after 2 years of use. It is recommended that medicated IUDs, free of side effects, be exchanged only after 5 years of use, corrosive changes being not too far advanced after this period. New IUD models are less likely to be subject to corrosion and will therefore need to be replaced less frequently.

Age Factors↗
PubMed1979

[Influenza immunization, clinical results and serological tests (author's transl)].

207 patients of a geriatric department were immunized against influenza with either tween-ether-split-vaccine or subunit-vaccine in a double blind study. For 6 months the following data were daily registered: rest in bed, fever over 38,5 degrees C, rhinitis, laryngopharingitis, bronchitis, pneumonia, enteritis, medication with antibiotics or chemotherapeutics. In cases with fever over 38,5 degrees C blood tests were taken for serological examination. The immune response against influenza A was excellent in both groups, the titer was higher in the subunit group, only one patient showed influenza infection. The immune response against the type B Hongkong was not satisfactory in both groups. The clinical data showed a significant lower incidence of rhinitis, laryngopharingitis and bronchitis in the group immunized with the tween-ether-split-vaccine. This effect was more distinct within the first 3 months after the immunization than within the second 3 months.

Aged↗