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Biomedical subjects

T Gasser

Publications and source records attributed to T Gasser.

At least 19 recordsLinked to original sources
PubMed1992

Apomorphine test for dopaminergic responsiveness in patients with previously untreated Parkinson's disease.

We prospectively examined the predictive value of the apomorphine test for the therapeutic efficacy of sustained oral levodopa treatment in 62 patients with de novo Parkinson syndrome (no additional neurological deficit) who had not previously been treated with dopaminergic medication. Patients received 2 to 5 mg of apomorphine hydrochloride subcutaneously and a subsequent trial of oral levodopa of at least 3 months' duration. In three patients, response to apomorphine could not be evaluated owing to side effects experienced during the test. In the remaining 59 patients, the best predictor of response to oral levodopa was the apomorphine-induced relative decrease in the scores on the motor examination part of the Unified Parkinson Disease Rating Scale (UPDRS). At a cutoff value of 20% improvement in UPDRS scores, the test predicted the response to levodopa correctly in 50 patients (85%). The sensitivity of the test was 90%, specificity 88%. The positive predictive value was 95%. However, seven of 19 apomorphine test-negative patients experienced a good (n = 4) or partial (n = 3) improvement with levodopa therapy. Thus, the negative predictive value was only 63%. We conclude that response to apomorphine has a high predictive value for response to sustained oral levodopa treatment in most previously untreated patients, but a negative test should not preclude an adequate trial of oral levodopa.

Adult↗
PubMed1992

Marked reduction of striatal dopamine D2 receptors as detected by 123IBZM-SPECT in a Wilson's disease patient with generalized dystonia.

[123I]iodobenzamide-single photon emission computed tomography (IBZM-SPECT) was employed to study the distribution of dopamine D2 receptors in a patient with biochemically proven Wilson's disease presenting with generalized dystonia. IBZM is a dopamine D2 receptor antagonist with high affinity and specific binding to basal ganglia detectable by SPECT. IBZM-SPECT in this patient (age, 20 years) displayed a striatum to frontal cortex ratio of 1.2 compared to 1.55 +/- 0.05 (mean +/- SD) in normal controls (n = 7; mean age, 53.3 years). In parallel with this finding, MRI with heavily T2-weighted sequences showed atrophy and low signal intensity changes of the basal ganglia. There was no improvement of dystonia after a subcutaneous injection of apomorphine. In contrast, IBZM-SPECT of a neurologically asymptomatic Wilson's disease patient (age, 21 years) displayed a striatum to frontal cortex ratio of 1.6. The MRI scan of this patient was normal. It is suggested that the observed apomorphine-unresponsive generalized dystonia in this Wilson's disease patient is related to striatal lesions proven by IBZM-SPECT and MRI.

Adult↗
PubMed1992

Hypofrontality on topographic EEG in schizophrenia. Correlations with neuropsychological and psychopathological parameters.

Topographic EEG was performed in 17 DSM-III-R schizophrenic patients and in 15 sex- and age-matched healthy controls. Eleven patients were first-onset (neuroleptic naive) schizophrenics. EEG band power was compared with psychopathology, neuropsychology and neurological soft signs. The EEG was recorded at 14 topographic locations monopolarly and movements of the eye and of the lid were monitored by two bipolar electro-oculogram (EOG) derivations, one vertical and one horizontal. A multivariate correction of EOG artefacts was performed based on regression analysis with respect to EOG channels. Schizophrenic patients showed higher mean and median power in most bands. These differences were marked in the delta band, in the fast alpha and beta bands, in particular at left frontal sites. Delta power at F7 was by far the best separating variable between schizophrenics and controls in a discriminant analysis. Significant positive correlations were found between the Brief Psychiatric Rating Scale scores "Anxiety-depression" and "Activation" and power in the fast bands and negative ones between "Anergia" and the beta bands. Positive significant correlations emerged between the total score in the Negative Symptoms Rating Scale and the amount of delta power, predominantly over the temporal region. Impairment in the Luria-Nebraska neuropsychological scores "Rhythm" and "Memory" correlated highly significantly with EEG band power. No correlations were found between neurological soft signs and EEG band power. Our results are in line with the hypothesis of a hypofrontality in schizophrenia. It is unlikely that these findings are an artefact of prior psychiatric treatment, as they were also observed in first-onset, neuroleptic naive schizophrenics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The deleterious effect of ocular artefacts on the quantitative EEG, and a remedy.

The effect of ocular artefacts on spectral EEG parameters is assessed statistically. These artefacts are caused by movements of the eyeball and/or of the lid. Further, methods for correcting ocular artefacts are presented and evaluated. This methodological study is based on data from an investigation comparing the EEG of schizophrenic patients (n = 17) with healthy controls (n = 15). Ocular artefacts are monitored by the bipolar vertical and the bipolar horizontal electro-oculogram (EOG). It is shown that the influence of ocular artefacts on the measured electrical activity in the frontal region is larger than the cerebral potentials which the EEG is ideally intended to record. The more frequent occurrence of blinks and eye movements in schizophrenic patients may lead to an artificial enhancement of slow frequency EEG power for schizophrenics and eventually "false significances". In contrast to this, we found more significant group differences when correcting for EOG artefacts than without it. This can be attributed to a very much inflated sample variability of the uncorrected EEG, due to the individually varying EOG power. We conclude that it may not be sufficient to select visually epochs for analysis that are considered artefact-free. Rather, one should monitor EOG artefacts and apply an appropriate correction.

Artifacts↗
PubMed1992

Folinic acid therapy fails to improve early Parkinson's disease: a two week placebo controlled clinical trial.

Folinic acid (15 mg bid, po) was administered in a two week, double-blind, placebocontrolled, cross over clinical trial in 5 patients with Parkinson's disease (Hoehn and Yahr stage I or II). 4 patients had not been on L-dopa treatment prior to entering this trial and one patient was on a small dose of L-dopa. No significant improvement could be detected in this pilot study by clinical evaluation and motor performance assessed by a computer assisted motor performance test.

Adult↗
PubMed1992

The autosomal dominant dystonias.

Dystonia is a term used to describe a specific set of abnormal movements that can occur as a symptom of a variety of neurologic disorders, but also as a disease entity in its own right. This review focuses on the primary dystonias and delineates the genetic contribution to these disorders. Included is a description of the well recognized forms of primary dystonias which manifest autosomal dominant inheritance, especially the "classic" type of early onset, generalized torsion dystonia, but also other clinically distinct forms such as myoclonic dystonia, paroxysmal dystonia, and DOPA-responsive dystonia. Also, a summary of the molecular genetic studies pertinent to these disorders and a discussion of the implications of recent genetic research for delineating the wide spectrum of this phenotypically and genetically heterogeneous group of diseases are forthcoming.

Alleles↗
PubMed1992

123I-iodobenzamide-SPECT predicts dopaminergic responsiveness in patients with de novo parkinsonism.

We used 123I-iodobenzamide-single photon emission computed tomography (IBZM-SPECT) in a prospective study to investigate 38 patients with parkinsonism (Hoehn and Yahr stage I to III) not previously treated with dopamimetic drugs. Thirty-four patients only showed symptoms of Parkinson's disease, and four patients showed, in addition, subtle clinical signs of progressive supranuclear palsy or multisystem atrophy. IBZM is a dopamine D2 receptor antagonist detectable by SPECT. We compared IBZM-SPECT results with clinical response to subcutaneous injections of the D1/D2 dopamine receptor agonist apomorphine (38 patients) and long-term dopamimetic therapy (31 patients). IBZM-SPECT results predicted a positive or negative response to apomorphine in 30 of 34 patients (apomorphine response in four patients was equivocal) and response to dopamimetic therapy in 27 of 31 patients. Thus, imaging of dopamine D2 receptors using readily available IBZM-SPECT seems to distinguish between L-dopa-responsive (most likely Parkinson's disease of Lewy body type) and L-dopa-unresponsive parkinsonism in patients not previously treated with dopamimetic drugs.

Adult↗
PubMed1991

Analysing curves using kernel estimators.

In this paper a novel statistical method for curve fitting is described and applied to growth data for illustration. This technique, called kernel estimation, is non-parametric and belongs to the class of smoothing methods. Therefore, it does not need an a priori functional model where individual parameters are determined from the data. Functional models can only reflect features which have been incorporated into the model. Recent progress in selecting the degree of smoothing from the data makes the new method more easy to use and more objective. It applies to the curve itself or to its derivatives.

Growth↗
PubMed1991

MICs of ciprofloxacin and trimethoprim for Escherichia coli: influence of pH, inoculum size and various body fluids.

The influence of pH, inoculum size, human urine and prostatic extract on the MICs of ciprofloxacin and trimethoprim for Escherichia coli was investigated. There was no influence by the bacterial inoculum size within wide ranges on either drug. An increase in pH had a variable influence on the MICs of trimethoprim for E. coli but lowered those of ciprofloxacin considerably. Human prostatic extract increased the trimethoprim MIC for E. coli but lowered those of ciprofloxacin as compared to Mueller Hinton broth. Human urine increased the MICs of both drugs for E. coli.

Animals↗
PubMed1991

[Neurogenetics--the challenge for neurology. Part 1. Gene mapping and gene diagnostics].

Recent advances in gene mapping have provided distinct chromosomal locations for a number of neurological disease genes. Mapping strategies include the identification of chromosomal aberrations associated with disorders and the candidate gene approach which requires correct assumptions about the primary biochemical defect. The most successful strategy, linkage analysis, relies on family studies and allows the mapping of genes without knowledge of the molecular cause of a disorder. Once the chromosomal position for a disease gene is known, indirect DNA diagnosis becomes available, providing risk estimates for individuals in affected families. Identification of the disease gene itself allows the characterization of the protein involved and direct diagnosis at DNA and protein level, thus leading to a greater understanding of the molecular pathology of neurogenetic disorders.

Chromosome Mapping↗
PubMed1991

[Neurogenetics--the challenge for neurology. 1. Neurogenetic diseases].

Progress in molecular genetics has provided insight into a number of neurogenetic disorders. The chromosomal location of the genes for Huntington's disease, Wilson's disease, myotonic dystrophy and Friedreich's ataxia are now known. In families affected by these illnesses, linkage analysis can now be employed for presymptomatic or prenatal diagnosis. The genes for Duchenne and Becker muscular dystrophy and neurofibromatosis I have been cloned and sequenced, allowing the direct analysis of the genetic defect in many cases, and thereby providing further insight into the pathophysiology. In addition, the classification of several neurogenetic diseases, such as the hereditary motor and sensory neuropathies or the spinal muscular atrophies can now be based on the chromosomal location of the affected gene(s).

Chromosome Mapping↗
PubMed1990

EEG power and coherence while male adults watch emotional video films.

Quantitative EEG analysis recorded at F3, F4, T3, T4, P3, P4 was performed for a group of healthy right-handed male adults (n = 9) viewing video films varying in their inductiveness on the affective valence dimension. Digital EOG-correction permitted the inclusion of trials with eye movements. Muscle artifacts were statistically treated by means of analysis of covariance (ANCOVA). The configuration of topographically motivated EEG parameters corresponded to the subjective valence rating of different video films. Low broad band coherences (COHs) ranked films along the subjective ratings within each hemisphere by the fronto-temporal COHs and interhemispherically by the T4-T3 COH, as did, restricted to the right hemisphere, similarity of beta 2 band power topography over time. High frequencies may be involved in the processing and low frequencies in the transmission of differential affective information, which to integrate seemed to utilize resources of both hemispheres. Alpha 2 and beta 1 COHs were sensitive to variations in an integrality/disassociation dimension with regard to the arrangement of verbal-visual affective cues. Power fluctuations at frontal leads pointed to difficulties in interpreting interhemispheric EEG asymmetries in emotion research, if information on time dynamics is discarded.

Adult↗
PubMed1990

Pubertal growth in chronic renal failure.

We evaluated the growth records of 15 boys and 14 girls who developed end-stage renal failure before or during puberty and who were regularly followed from the onset to the end of their pubertal growth spurt. Height data were smoothed by using the kernel estimation method. Mean values for age, height, and height velocity at defined points of the pubertal growth period were compared with those of normal children entering puberty both at an average and late age. The start of the pubertal growth spurt was delayed by 2.5 y in both sexes. Its duration and intensity were significantly reduced. Mean pubertal height gain was 17.3 cm in boys and 13.9 cm in girls, i.e. 58 and 48% of that observed in the late maturing control group. Mean height at the onset of the pubertal spurt in the patients was the same as that in the late maturing healthy girls and 1.0 SD below that of corresponding boys. During the pubertal growth spurt, mean height declined to -2.9 SD in boys and -2.3 SD in girls. Although skeletal maturation was increasingly retarded, we did not observe accelerated growth velocity during late puberty. Our data indicate that most patients reaching end-stage renal failure before or during puberty irreversibly lose growth potential during this period. Renal transplantation did not consistently improve pubertal growth.

Adolescent↗
PubMed1988

Effect of carbamazepine on stimulus-evoked Ca2+ fluxes in rat hippocampal slices and its interaction with A1-adenosine receptors.

In rat hippocampal slices superfused with a medium lacking Mg2+ ions, CA1 neurons generated burst discharges which were sensitive to blockade by 2-amino-5-phosphonovaleric acid (APV) and antagonized by 20-50 microM carbamazepine (CBZ). Decreases of [Ca2+]o (delta Ca), evoked by repetitive synaptic activation, were reduced in the presence of CBZ by 20-50%, associated with a reduced membrane depolarization. CBZ also abolished an APV-sensitive increase of delta Ca in the synaptic area elicited by theophylline. CBZ inhibited binding of the A1-adenosine receptor antagonist, [3H]8-cyclopentyl-1,3-dipropylxanthine [( 3H]DPCPX), in a dose-dependent manner. The displacement curve was shifted to the left in the presence of guanine nucleotide, suggesting that CBZ acts as an antagonist at A1-receptors. It is concluded that CBZ exerts its electrophysiological actions in the hippocampus at a site beyond the ligand recognition moiety.

2-Amino-5-phosphonovalerate↗