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Biomedical subjects

G Ulrich

Publications and source records attributed to G Ulrich.

At least 73 records · Page 4Linked to original sources
PubMed1987

Fibronectin and collagens modulate the proliferation and morphology of astroglial cells in culture.

The proliferation and morphology of astroglia derived from neonatal rat cortex and cultured in serum-free medium on either untreated, or fibronectin-, or collagen I-, or collagen IV-treated substrates were investigated using tritiated thymidine autoradiography and immunocytochemical staining of glial fibrillary acidic protein (GFAP) and actin. Modification of culture substratum with fibronectin enhanced the rate of proliferation of astroglial cells and increased the proportion of process-bearing astroglial cells. The distribution of actin and patterns of adhesion observed were typical for motile cells. Both types of collagen decreased the proportion of astroglial cells undergoing mitosis. Many of the astroglial cells exhibited a flat morphology and displayed prominent stress fibres in the cell body and processes. The data suggest that specific interactions with the substratum modulate the proliferation and morphological behaviour of astroglial cells.

Animals↗
PubMed1987

[Functional adjuvant for stored red blood cells: ascorbate or oxalate?].

In stored blood cells the p50 and the 2,3-DPG concentration drop rapidly. To compensate the functional resultant weakness, many different additives have been proposed, in particular ascorbate, which is very unstable, and ascorbate-2-phosphate (AsP), which is a little more stable. We have studied the effect of two commercially available AsP whose impurity content was different. It was found that the more the substance was impure the more it was effective. This led as to doubt the effectiveness of ascorbate itself and to try the impurity (oxalate) with which we have obtained the results published with AsP.

Ascorbic Acid↗
PubMed1987

[Electroencephalographic foci without structural diagnostic correlates].

On account of the increasing availability of various new, computer-aided and non-invasive imaging techniques it seems advisable to reconsider the structural-diagnostic use of the EEG which is a functional-diagnostic instrument by its nature. On the level of visuo-morphologic description local and locally accentuated patterns can only be conceived as deformations of the temporo-spatial gestalt of the EEG. On the level of interpretation, i.e. in answering the question whether such patterns are indicative of a circumscribed structural lesion or not, further information is required. In addition to clinical data such information is provided by the electroencephalographic context. Typical arrangements of the EEG-context which make improbable an assumption of a structural lesion can be demonstrated for certain anterior-left as well as posterior-right localized patterns. From such regular co-incidencies, which are illustrated by paper chart examples, we conclude that these "foci" represent local manifestations of a global functional impairment. Whereas the intermittently occurring anterior-left accentuated slow wave patterns refer to an incipient global functional disintegration, the posterior-right accentuated slow wave patterns can be regarded as a reflection of a global functional deficit of maturation. A third phenomenal domain which persistently confronts us with the structural-diagnostic limitations of the EEG consists of the focal patterns in patients with epilepsy. It may be assumed that the pronounced lateral inconsistency of these focal patterns, occurring within the recording period and even more when comparing serial recordings, is dependent both on the actual (vigilance) and the relatively outlasting level of central nervous organization (maturation).

Brain Damage, Chronic↗
PubMed1987

[Psychophysiology of schizophrenic disorders of attention--concepts, findings and working hypotheses].

Starting from early clinical descriptions according to which there exists a polarity of attentional behavior in schizophrenia, we compare a number of pertinent theoretical concepts put forward up to now. Special attention is given to the question of functional hemispherical asymmetries, and here especially to a working hypothesis according to which the neuropsychological deficits in schizophrenics result from a coordination deficit of two differently lateralized attention systems. Taking into consideration certain neurophysiological (especially electro-encephalographical) findings, we discuss a model which places in opposition sensory intake behaviors and sensory rejection behaviors. Then we give a condensed presentation of relevant findings of our own. In particular, it could be shown that clinical improvement goes along with a certain change of the topographical distribution of absolute alpha-power, and that the intensity of some psychopathological symptoms correlates with the lateralization of posterior absolute alpha-power. Relationships also occurred between psychopathology on the one hand and the performance level in a visuo-motor tracking task or the eye movement behavior recorded during a picture viewing task, on the other. A concluding synopsis, comprising both empirically proven and theoretically postulated relationships, serves to formulate working hypotheses for clinical-psychophysiological correlation studies to be done in the future. In contrast to the current practice of assigning patients to the usual diagnostic subgroups, we advocate from a research-oriented point of view the grouping of those patients who show certain combinations of clinical and psychophysiological signs at a certain moment. Such a procedure holds out a prospect of solving a central problem of schizophrenia research consisting of the considerable intra- and individual variability of findings. Instead of changeable sick persons, defined systems states would be classified. Knowledge of the dynamics of such systems states could contribute to a rational therapy in the individual patient.

Attention↗
PubMed1987

Auditory evoked potentials and response to lithium prophylaxis.

Auditory evoked potentials were recorded in 28 euthymic patients with affective psychosis who had received lithium prophylaxis for at least 5 years. Binaural clicks at 4 intensities were presented in randomized order via headphones. Potentials were recorded from Cz, C3, and C4 referenced to linked mastoid electrodes. N1-P2 amplitudes, N1 and P2 latencies, and the slope of the amplitude/stimulus intensity function (ASF) were determined in each patient. The patients were divided into responders and nonresponders on the basis of whether or not they had been hospitalized for treatment of relapses during the last 5 years of lithium prophylaxis. The ASF was steeper for all leads in responders than in nonresponders. In addition, N1 latencies were shorter for all leads in responders than in nonresponders. Age played a role in the differences observed between responders and nonresponders for ASF, but not for N1 latencies.

Adult↗
PubMed1987

Visuomotor tracking performance in schizophrenia: relationship with psychopathological subtyping.

30 schizophrenic outpatients (RDC) under neuroleptic maintenance treatment completed a visuomotor tracking task with four degrees of difficulty. The mean efficiency of performance was measured in bit per second from the difference between the target signal and the tracking signal. Clinical assessment was accomplished with the BPRS, CGI, and GAS. Besides generally poorer tracking performance in schizophrenics compared with healthy volunteers the main finding was a relationship between tracking performance and psychopathological subtyping. Negative symptoms were related to a generally lowered task performance, irrespective of task difficulty. However, this effect disappeared by controlling for illness duration. On the other hand, there was a syndrome-specific interaction effect with task difficulty: Schizophrenics with positive symptoms performed poorly, especially in the most difficult task condition. Generally, there was no significant relationship between daily neuroleptic dose and tracking performance. Results are discussed with respect to a differential deficit in attention in schizophrenic subgroups.

Adult↗
PubMed1987

[A computer-assisted visuomotor tracking device for the selective observation of central nervous drug effects].

A Computer-assisted Visuomotor Tracking Device for Selective Objectivation of Central-nervous Drug Effects. In order to overcome the well-known shortcomings of current psychometry especially for the objectivation of the effects of psychotropic drugs, a computer-assisted visuomotor tracking device has been developed. The subjects task is to closely pursue a target signal which moves continuously but at variable speed on a TV-screen by directing a response signal on the screen with a small joystick. In contrast to conventionally used visuomotor tracking tasks the mean efficiency of the performance is measured exactly in bit/s from the difference between target and response signal. First applications showed: The selectivity of the procedure depends decisively on the degree of difficulty of the target signal, i.e., the velocity of the target signal. There is no substantial learning effect with re-tests at a 1-week interval. When testing over longer periods (400 s) a decrement of performance must be taken into consideration.

Adult↗
PubMed1987

[The effect of terguride on the dynamics and mean level of vigilance. A controlled electroencephalographic study with elderly subjects].

The influence of a 3-week medication period with terguride (trans-dihydro-lisuride) in a dosage of 2 X 0.2 mg/d per os upon the 10-min resting EEG of elderly, clinically normal volunteers (mean age 70 years was investigated. Eight subjects received placebo and 7 subjects received terguride under double-blind conditions. The EEG data were analysed, inter alia, by a newly-developed method of quantification which uses information on topographical relationships of the absolute alpha-powers provided by two anterior and two posterior leads. Under terguride, but not under placebo, a significant increase of subvigilant patterns was found. If one were to disregard the baseline situation, which was characterized in the present sample by a distinct restriction of the physiological dynamics of vigilance at a reduced level (dynamic rigidity), this finding would have to be interpreted as sedation. A non-physiological pre-drug situation was indicated by marked and sustained anteriorization of alpha-activity. Taking into account our additional finding that terguride, but not placebo, eliminates this non-physiological alpha-anteriorization, we interpret the increase of subvigilant patterns in the course of the recording period as a resolution of the preexisting dynamic rigidity and, consequently, as a therapeutically desirable effect.

Aged↗
PubMed1987

[The effect of nimodipine on topical distribution of absolute alpha-power in the EEG and the concurrent state of wellbeing in healthy subjects].

A double-blind cross-over comparison between the calcium antagonist nimodipine (Nimotop) and placebo with a group of 14 young, healthy volunteers showed the following: The effect of nimodipine on the EEG consists of changes in the anterior-posterior relations of absolute alpha-power which are considered to be an indicator of the vigilance level. This effect can only be demonstrated when the individual baseline (placebo-EEG) is taken into consideration. The group has been dichotomized into half-groups with higher and lower levels of vigilance. The half-group with higher levels of vigilance (n = 7) showed a decrease, the half-group with lower levels of vigilance (n = 7) showed an increase of vigilance under nimodipine. The decrease of the vigilance level was accompanied by an improvement of self-rated well-being, the increase with a deterioration. These results support earlier findings according to which nimodipine interindividually effects a stabilization of vigilance at a medium level.

Adult↗
PubMed1986

Eye movement research with schizophrenic patients and normal controls using corneal reflection-pupil center measurement.

The eye movements of 20 partially remitted outpatient schizophrenics (ICD 9), for the most part receiving neuroleptic maintenance medication, and 20 normal controls were recorded using corneal reflection-pupil center measurement. Performance was investigated on the basis of widely varied measurement parameters during a fixation task and a visual search task (list of letters). Psychopathological data were additionally recorded for the group of patients by means of self and observer ratings, current social adjustment, and neuroleptic dosage. The schizophrenic patients showed the tendency to perform more poorly than the normal controls in the eye movement parameters recorded, and there was marked variation in performance within the group of schizophrenic patients. In particular, various abnormalities in fixation performance were connected differentially with individual psychopathological syndromes and neuroleptic dosage. Connections between fixation performance and search performance were found only within the group of patients. They are interpreted as an indicator of disturbed interhemispheric coordination in schizophrenics. Based upon specific pupillary findings one concludes that the processing load imposed on the attentional system by the search task is different for various schizophrenic subgroups.

Adult↗
PubMed1986

The organization and solubility properties of intermediate filaments and microtubules of cortical astrocytes in culture.

The organization of intermediate filaments (IF) and microtubules (MT) and the solubility of intermediate filament proteins and tubulin in astrocytes which develop from cerebral hemispheres of neonatal rats in culture were examined using immunocytochemical and immunochemical approaches. Results of immunocytochemical studies demonstrated that in flat astrocytes which develop after 3 weeks of culturing in serum-supplemented medium, the IF containing vimentin and glial fibrillary acidic protein (GFAP) are concentrated around the nucleus and dispersed in an irregular fashion throughout the cytoplasm. Astrocytes which develop in serum-free hormonally-defined medium irrespective of whether they are bipolar, multipolar or flattened, have IF organized as a fibrous network of filaments distributed from the nuclear regions to the cell periphery. Under both culture conditions, vimentin and GFAP are resistant to extraction with low salt buffer containing nonionic detergent, indicating that the different cytoplasmic distribution of IF is unrelated to the solubility properties of vimentin and GFAP. Double immunolabelling experiments with polyclonal antibody to GFAP and monoclonal antibody to each alpha-tubulin or beta-tubulin reveal an extensive codistribution and parallel organization of IF and MT in all morphological types of astrocytes studied. Stabilization of MT with taxol, or depolymerization of MT with colchicine, cause dramatic changes in the distribution of IF and inhibit the extension of astrocyte processes in response to dibutyryl cyclic AMP (dBcAMP). In early stages of treatment with dBcAMP, renewal of culture medium without dBcAMP produces a rapid and permanent retraction of astrocyte processes, whereas in later stages the processes only retract partially and are then restored and maintained for several days in the absence of dBcAMP. The retraction of processes is accompanied by changes of immunocytochemical staining of IF with antibody to GFAP, which appears more intense and diffuse. However, electrophoretic and immunoblot analyses of detergent-extracted proteins from parallel cultures demonstrate that neither the amount nor the solubility of GFAP and vimentin are changed. Detergent extraction in MT stabilizing conditions shows that a substantial proportion of tubulin in astrocytes cultured in serum-containing and serum-free media is assembled into MT, most of which depolymerize on treatment with low temperature and Ca2+. Following long exposure to dBcAMP the proportion of cold/Ca2+-stable MT increases. The results suggest that the IF of astrocytes in culture are dependent on MT with respect to their cytoplasmic distribution.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkaloids↗
PubMed1986

A new quantitative approach to the assessment of stages of vigilance as defined by spatiotemporal EEG patterning.

Electroencephalographically oriented research on vigilance needs valid measures for assessing the level of vigilance between wakefulness and sleep. When studying different psychologically, psychopathologically, and pharmacologically induced states, special attention has to be paid to minor alterations of the level of vigilance which are reflected, essentially, in topographical changes of alpha-activity (Stage A). Since vigilance is a dynamic process, brief fluctuations in the range of a few seconds must also be recorded. In our opinion existing methods of quantification do not fully meet these demands. We have, therefore, developed a relatively simple procedure which can be characterized as an attempt quantitatively to reconstruct visually, i.e., spatiotemporally defined patterns of vigilance. The usefulness of this method, which also has certain limitations, has been demonstrated in psychopharmacological studies.

Alpha Rhythm↗
PubMed1985

A video analysis of the non-verbal behaviour of depressed patients before and after treatment.

Using videotaped interviews of depressive in-patients, which were recorded on day 0 and day 21 of antidepressive pharmacotherapy, the behavioural structure of the syndromal main aspects, retardation and agitation, was analysed. This analysis was done on the basis of non-verbal behaviour only. A factor analysis was carried out on the observational data. Three independent factors, constituting together the clinical picture of endogenous depression, could be defined: one factor of retardation and two different factors of agitation. The importance of such non-verbal analyses for a more differentiated diagnostic evaluation, on the one hand, and to provide more insight into the diagnostic process as such, on the other, is pointed out. Additionally it was found that syndromal complexity decreases in a characteristic manner along with clinical improvement.

Adult↗
PubMed1985

The lateralization of occipital alpha-power under resting conditions in the EEG of healthy volunteers. A state- and a trait-variable.

Using a structural analysis of lateralization of occipital alpha-power in 20 healthy volunteers under resting conditions, a clear vigilance-dependence could be shown for the great majority. In contrast the state of four subjects showed almost no dependence on vigilance. Additional findings according to which these two subgroups also differ in a characteristic manner with regard to various other aspects, especially occipital alpha-quantity and vigilance dynamics, point to a maturational dimension.

Adult↗
PubMed1985

Asymmetry of occipital alpha-rhythm under resting conditions: a neurophysiological measure of "hemisphericity".

Using the resting EEGs of 20 healthy subjects in semirecumbent position with eyes closed and left undisturbed, we studied the question whether and, if so, to what extent, lateralization of occipital alpha-rhythm depends on level of vigilance. As a simple indicator of vigilance, the relative alpha-power for each 2-sec. epoch of 02-CZ (occipital right) was calculated. Lateralization was defined as the ratio of absolute alpha-powers in 01-CZ and 02-CZ (occipital left and right). This was also calculated epoch by epoch. The results of individual analysis of data from each subject allowed categorization into 3 types. This typological differentiation obtained quantitatively could be supported by visual pattern analysis. The findings are discussed in relation to the state- vs trait-problem which constantly confronts us when we interpret experimentally obtained functional asymmetries of hemispheres.

Adult↗