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Biomedical subjects

G Zeller

Publications and source records attributed to G Zeller.

At least 19 recordsLinked to original sources
PubMed1991

Comparative effects of dopamine and dobutamine on glucoregulation in a rat model.

The influence of dopamine as compared with dobutamine on glucose homeostasis has been assessed in thyroidectomized euthyroid rats. Both sympathomimetic agents were given intravenously over 6 h at four dosages, varying from 2 to 30 micrograms.kg-1.min-1. Immediately before the end of the infusion period, serum concentrations of glucose and insulin as well as plasma glucagon concentrations were measured. Dobutamine infusions did not exert any influence on these parameters. At a dose of 7.5 micrograms.kg-1.min-1, dopamine infusion caused a decrease in glucose concentrations, accompanied by a rise of glucagon and insulin levels. Glucose levels were significantly increased in the presence of unaltered insulin and decreasing glucagon levels at higher dopamine doses. The rise in glucose levels was reversed by 8 micrograms.kg-1.min-1 and inverted to a decrease by 12 micrograms.kg-1.min-1 of the alpha-adrenergic blocking agent phentolamine, simultaneously infused with 15 micrograms.kg-1.min-1 dopamine, while the insulin levels were increased and glucagon levels remained elevated. These findings demonstrate that dopamine acts on glucoregulation divergently, according to the dosage applied. The data suggest that dopamine rather than dobutamine treatment may disturb glucose homeostasis.

Animals↗
PubMed1991

Hepatic sulfhydryl content under adrenergic stimulation in male rats.

The influence of a series of sympathomimetic agents on the liver content of non protein bound thiol groups (NP-SH), mainly representing glutathione, has been assessed in the male rat. The rats were intravenously and/or subcutaneously infused over 6 h at different dosages either with dopamine, dobutamine, epinephrine, terbutaline, or phentolamine, or simultaneously with dopamine and phentolamine, or with epinephrine and phentolamine. Besides NP-SH, total sulfhydryl group content was measured in liver cytosol, while glucose and insulin concentrations were determined in the serum. Liver NP-SH content was significantly decreased by epinephrine. This decrease was abolished and even inverted to an increase, when appropriate doses of phentolamine were infused simultaneously. Dopamine caused a rise in NP-SH content at a dose rate of 7.5 micrograms/kg.min, while lower and higher dose rates of dopamine exerted not any influence on liver NP-SH. When phentolamine was concomitantly infused with 15 micrograms/kg.min of dopamine, NP-SH was significantly elevated. Phentolamine, when infused exclusively, increased NP-SH as well, while it was not influenced, however, by terbutaline or dobutamine at any dosage. Cytosolic total sulfhydryls were found to be unaltered across all experimental groups. When the NP-SH values are related to the corresponding serum insulin levels, a close and linear relationship becomes evident. The study demonstrates, that some sympathomimetic agents can exert a considerable influence on hepatic non protein bound thiol content. The data suggest, that the varying liver NP-SH content under adrenergic drugs is primarily related to changes in serum insulin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Differential effects of dopamine on glucoregulatory hormones in rats.

The effect of dopamine at different doses on serum concentrations of insulin, glucose and corticosterone and on plasma glucagon concentration was investigated in rats. Dopamine was given intravenously over 6 h with infusion rates of 2.5, 7.5, 15, and 60 micrograms/kg.min and in combination with phentolamine. Serum insulin concentration was unchanged at low doses of dopamine. It was significantly increased from 6.0 +/- 0.7 ng/ml to 13.7 +/- 2.3 ng/ml (P less than 0.01) when 7.5 micrograms/kg.min of dopamine were used, whereas it was significantly depressed to 3.96 +/- 0.89 and to 4.0 +/- 0.34 ng/ml (P less than 0.01), respectively, at the high doses of dopamine. This latter effect could be reversed to 6.7 +/- 1.19 ng/ml and inverted to 9.2 +/- 1.7 ng/ml (P less than 0.01) by simultaneously applied phentolamine at appropriate dosages. Serum glucose levels were markedly elevated from 154 +/- 7 to 234 +/- 42 mg/dl (P less than 0.01) by the higher doses of dopamine. A significant alteration of glucagon plasma concentrations from 18.9 +/- 2.8 to 42.3 +/- 14 pg/ml (P less than 0.01) was elicited only by 7.5 micrograms/kg.min of dopamine. The data clearly demonstrate that exogenous dopamine acts differently on glucose homeostasis according to the dosage. The study provides strong evidence that dopamine decreases insulin levels via alpha-adrenergic receptor stimulation. This effect may contribute to the deterioration of glucose homeostasis with high doses of dopamine.

Animals↗
PubMed1990

Glucoregulation under beta-adrenergic stimulation by dobutamine and terbutaline in the male rat.

The influence of the beta-adrenoreceptor stimulating agents dobutamine and terbutaline as compared to epinephrine on insulin and glucose levels has been assessed in the male rat. All agents were infused either intravenously or subcutaneously over 6 h at varying dosages. In addition, epinephrine was given concomitantly with the alpha-adrenoreceptor blocker phentolamine. The heart frequency as an estimate of the effects of the adrenergic agents beyond the glucoregulatory system was accelerated in a dose-dependent manner. Serum insulin concentrations were significantly increased by phentolamine and significantly depressed by epinephrine, while they were virtually unchanged at any dosages of dobutamine, terbutaline, or epinephrine, when simultaneously applicated with phentolamine. As for serum glucose levels, these agents, again, did not exert any influence, while glucose levels were significantly depressed under phentolamine and significantly increased under epinephrine application. The data demonstrate, that dobutamine and terbutaline at pharmacologically common dosages do not affect glucose homoeostasis. The study does not support a major effect of beta-adrenergic stimulation on the pancreatic B cell in the male rat.

Adrenergic beta-Agonists↗
PubMed1987

The prognosis of retinoblastoma in terms of globe saving treatment. A computer assisted study. Part I.

At present there is no satisfactory classification or staging system. In order to compare the Reese classification (Reese & Ellsworth, 1963), the Essen classification (Höpping, 1983) and a new classification, a method of evaluating different parameters was created to get an optimal classification of globe saving treatment. A computer score table for the Essen eye clinic was established and this table could be valuable for all clinics using modern methods of treatment.

Decision Making, Computer-Assisted↗
PubMed1986

[Indications for tocolysis. A prospective study].

In a prospectively randomised group of pregnant patients showing signs of prematurity, who had undergone long-term tocolysis between the 28th and 38th week of gestation--mainly with Fenoterol--the interval between the end of the tocolytic therapy and the delivery is noted. According to the duration of the end of tocolysis to delivery interval (TEDI) the indication for tocolysis can be retrospectively investigated. In patients where the TEDI was 72 hours or less, tocolysis is regarded as being necessary, and in patients with TEDI of longer than 72 hours, tocolysis is regarded as questionable or unnecessary. In this study in 49% of the cases tocolysis was necessary, whereby the primapara had a shorter TEDI on the average than the multipara. Both groups with short and long TEDI are compared with reference to obstetrical parameters, whereby virtually only the greater anamnestic strain of the patients with short TEDI emerged. There is not easily recognizable uniform criterion which can identify prospectively those patients whose baby is born within 72 hours after the tocolytic therapy has been discontinued. The results are discussed under the aspect of unsolved problems in the indication for tocolytic treatment.

Aspirin↗
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↗
PubMed1984

Interrelation between changes in the EEG and psychopathology under pharmacotherapy for endogenous depression. A contribution to the predictor question.

With the predictor problem in mind, we studied in-patients with endogenous depression whether relationships exist among the EEG, the therapeutic response, and the severity of psychopathology. We found that clinically defined responders and non-responders differ in respect of their average power spectra calculated for the two occipital regions. In addition, it was shown that there is a statistically significant correlation between the EEG before treatment and the severity of AMP-documented psychopathology after a 4-week treatment period. This correlation was stronger for the left occipital region than for the right.

Amitriptyline↗
PubMed1983

[Laterality of hospitalized endogenous-depression patients].

Compared to normals, groups of inpatients with unipolar and involutional depression show a higher proportion of consistent right-handers, whereas bipolar patients do not differ from normals. All patient-groups show a clearly higher proportion of persons with a "dominance" of the right thumb when habitually clasping the hands or fingers. The variables "eyedness" and "familial sinistrality" do not show significant differences between groups. When drawing geometric figures in a bimanual-coordinated fashion, all patient groups demonstrate a prevalence of simultaneous counter-clockwise drawing with both hands, whereas normals overwhelmingly prefer a discordant mode of drawing, the left hand acting counter-clockwise and the right hand clockwise. We interpret this behavior in depressives to be an expression of an interhemispheric functional relationship in which the left hemisphere is subordinated to the right hemisphere.

Adult↗
PubMed1983

[Changes in the electric organization of the brain in visual search and discrimination processes of different degrees of difficulty].

EEG activity during visual search processes with different degrees of discrimination difficulty was investigated in 13 male subjects. In accordance with the paradigm used by Neisser, 17 corresponding lists of rounded or angular letters were displayed. The task was to select the target letter Z from each list. The discrimination of the letter Z out of the lists of angular letters is the more difficult task. Spectral analysis shows a significant change in alpha-frequency structure during the more difficult search process. There is a shift of the dominant alpha-frequency from 11.5 to 10 Hz with a significant increase and concentration of power in the dominant frequency. This concentration of alpha-power around 10 Hz is more pronounced in the right occipital region than in the left. Concomitantly, there is a significant increase of power in subharmonic theta-frequencies. By consecutive principal analysis of spectral data these results were further differentiated and confirmed. The changes in the alpha- and theta-band during the more difficult search process are the expression of a complex transformation of EEG-frequency structure and patterning which cannot be interpreted by the usual concepts based on the theory of activation. Moreover, they seem to be the neurophysiological correlate of the accommodation (Piaget) of the neurodynamic processes to the altered perceptual conditions and to their effects on the internal matching process.

Adult↗