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Biomedical subjects

U Mayr

Publications and source records attributed to U Mayr.

At least 19 recordsLinked to original sources
PubMed1992

Validation of two in vitro test systems for estrogenic activities with zearalenone, phytoestrogens and cereal extracts.

In order to establish alternatives to the frequently used uterotropic assay with mice, defined estrogen-sensitive cell lines (MCF-7 cells and LeC-9 cells) were used to determine the estrogenic activities of purified compounds of vegetable origin (myco- and phytoestrogens) and zearalenone-contaminated forage cereals (wheat, barley and oats). In MCF-7 cells, a human breast cancer cell line, the induction of an estrogen-specific exoprotein served as a parameter of estrogenic activities. LeC-9 cells represent a genetically transformed cell clone derived from mouse L-cells. Here, hormone-like activities were measured by the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene under the control of an estrogen-responsive element. Toxic effects affecting cell viability were monitored in this system by the expression of a second reporter gene (the bacterial beta-galactosidase gene controlled by the constitutive human beta-actin promoter). Relative estrogenic activities of myco- and phytoestrogens determined with both systems are concomitant, but higher as compared to the uterotropic assay with mice.

Animals↗
PubMed1991

[Simultaneous effects and aftereffects of the intensity and success aspect in coping with stresses].

Intensity and success of coping processes in achievement-related situations are very often tightly connected. Therefore, the specific empirical status of each of the two aspects is unclear. In the current study a technique is introduced which allows orthogonal variation of both components. 64 subjects were confronted with a simple perceptual-speed task in which objective success rate was held constant by a computer-based adaptive process. Graphic feedback was provided about the objective success rate in relation to one of two different success criteria. For half of the subjects the criterion was above (failure condition) and for the other half it was below (success condition) the adaptively controlled success rate. Intensity, the second between-subjects factor, was manipulated by presenting either a high or a low number of items per time unit. As an additional quasi-experimental factor, the degree of action- vs. state-orientation (Kuhl, 1983) was included. The results showed highly specific effects for both the intensity and the failure/success dimension: High intensity resulted in an increase of electrodermal activity which could be observed throughout a one hour post-stressor phase. The failure/success variation had effects mainly on subjective variables representing appraisal of controllability and produced no after-effects. Especially strong effects on subjective variables could be observed when state-oriented subjects were confronted with both failure and high intensity.

Achievement↗
PubMed1988

Alternative mechanisms for gene activation induced by poly(rI).poly(rC) and Newcastle disease virus.

After poly(rI).poly(rC) induction of FS-4 fibroblasts, both human interferon-beta (IFN-beta) mRNA and an additional induced RNA class (12S RNA) hybridize to a genomic cosmid clone containing the human IFN-beta gene as well as 35 kbp of flanking sequences. However, this coinduced 12S RNA does not originate from regions in the neighborhood of the IFN-beta gene, but hybridizes to the genomic cosmid clone via repetitive Alu-family sequences. While IFN-beta mRNA rapidly decays after reaching a maximum 2-4 h after induction, this 12S RNA is stably maintained in the fibroblast cell for more than 16 h. Contrary to IFN-beta mRNA, the level of the 12S RNA is not further elevated by superinduction conditions (cycloheximide treatment) during poly(rI).poly(rC) induction. However, subsequent to treatment with the weaker viral inducer Newcastle disease virus (NDV) both IFN-beta and the 12S RNA transcripts are induced to a higher level in the presence of cycloheximide. Cell-free translation of hybrid-selected 12S RNA leads to detection of an induced protein of 14 kDa. cDNA cloning reveals that the 12S RNA contains part of an Alu-family sequence in the 5'-untranslated region. The 12S RNA is probably not an RNA polymerase III transcript and codes for a protein of 9 kDa (as monitored by in vitro cell-free translation). This discrepancy in molecular mass can be attributed to a retarded migration of the protein in SDS/PAGE.

Amanitins↗
PubMed1987

[Differential diagnosis of spinal processes using modern diagnostic procedures].

Modern diagnostic management of diseases of the spinal cord is discussed, illustrated by some exemplary cases and reviewed by the literature. Special attention is directed to high resolution tomography, magnetic resonance imaging, analysis of the cerebrospinal fluid and electrophysiological methods. It seems conceivable that a shift from invasive methods to noninvasive procedures (e.g. magnetic resonance imaging) may occur.

Angiography↗
PubMed1987

Macroprolactinomas and functionless pituitary tumours. Immunostaining and effect of dopamine agonist therapy.

In 32 patients with macroprolactinomas or functionless pituitary macroadenomas biochemical and clinical data were correlated with PRL immunocytochemistry. Serum PRL levels revealed a positive correlation with tumour PRL content. Hyperprolactinaemia of 3000 mU/l or more was found only in patients with PRL-positive tumours. In 15 patients with borderline hyperprolactinaemia (below 3000 mU/l), 7 PRL-positive and 8 PRL-negative macroadenomas were found, and in 9 normoprolactinaemic patients 4 PRL-positive and 5 PRL-negative macroadenomas. Patients with PRL-immunostainable tumours had significantly higher median basal serum PRL (P less than or equal to 0.05) than patients with PRL-negative tumours. PRL stimulation after TRH, basal and GnRH-stimulated FSH and LH did not show significant differences between the two groups. A discriminant analysis using 6 biochemical variables was attempted to differentiate between PRL-negative and -positive tumours, which would be helpful in patients with borderline hyperprolactinaemia. Dopamine agonist therapy led to suppression of serum PRL with few exceptions in patients with PRL-positive and -negative tumours, whereas shrinkage was only observed in PRL-immunostainable tumours with high serum PRL levels (over 18,000 mU/l). All patients with PRL-negative tumours showed no change or even growth of the tumour despite dopamine agonist therapy. Our observations indicate that a pituitary macroadenoma associated with serum PRL of more than 3000 mU/l is most probably a prolactinoma (tumour immunostainable for PRL). Dopamine agonist therapy is effective in PRL suppression and tumour shrinkage in most of these patients. Macroadenomas without hormone hypersecretion or with borderline hyperprolactinaemia below 3000 mU/l may or may not contain PRL-immunostainable cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1986

Activation of the ADP/ATP carrier from mitochondria by cationic effectors.

The ADP/ATP carrier from the mitochondrial inner membrane was found to be influenced by cationic substances from the hydrophilic surroundings. Under low-ionic-strength conditions, addition of these cationic effectors fully activated the reconstituted adenine nucleotide translocator. The list of activators included divalent cations, polyamines, peptides and cationic proteins. The minimum requirement for an activator to be effective was the presence of at least two positive net charges, regardless of the size of the molecule. Cationic molecules were not activating when an intramolecular charge compensation was possible or when the two charges were too far apart from one another. The affinity of these activators varied from several hundred microM (diaminoalkanes, divalent cations) to 1 microM (cytochrome c, spermine) and even down to a few nM (polylysine). The activation by cations was fully reversible and was not due to fusion processes. It was not mediated by an interaction with the anionic substrates ADP and ATP, nor by interaction with the liposomes. The stimulation could directly and functionally be correlated to the reconstituted carrier protein. Activation was not observed in intact mitochondria, but could be demonstrated when the outer mitochondrial membrane had been removed by treatment with digitonin. These mitoplasts were stimulated by polycations similar to the ADP/ATP carrier in the reconstituted system.

Amines↗
PubMed1986

Prognostic implications of the motor symptoms of Parkinson's disease with respect to clinical, computertomographic and psychometric parameters.

Forty-four Parkinson patients (19 patients of the rigid-akinetic type, 13, of the rigid-akinetic-tremor type, and 12, of the tremor type) were included in a study in order to analyse correlations of the expression of the motor symptoms tremor, rigidity, akinesia, with other clinical parameters, computertomographic aspect of brain atrophy and psychometrically assessed cognitive parameters. Rigidity and akinesia are significantly positively correlated with the severity of motor dysability, stage of the disease, and brain atrophy, as is akinesia with a history of pharmacotoxic psychosis. Tremor is significantly negatively correlated with motor dysability, stage of the disease, and history of pharmacotoxic psychosis. Akinesia is correlated with visuomotor dysfunction (tested with Bender Gestalt Test) and rigidity with the depression score (Zung scale). The tremor type is favorable, the rigid-akinetic type unfavorable with respect to motor disability and psychosis.

Adult↗
PubMed1986

Computer-tomographical appearances of the Chiari malformations of the posterior fossa.

The computer-tomography appearances of the Chiari I-III malformations are reviewed. The study is based on a series of 35 cases of Chiari I malformation, 116 cases of Chiari II malformation, and one case of Chiari III malformation. In our experience, a reliable diagnosis of all three types of malformation is possible on computer tomography. However, nuclear magnetic resonance imaging does reveal more detail and may become more important in the diagnosis of malformations of the posterior fossa structures.

Arnold-Chiari Malformation↗
PubMed1986

Secondary cerebral amebiasis due to infection with Entamoeba histolytica. A case report with computer tomographic findings.

The clinical and serological findings and computer tomographic (CT) appearances of a case of secondary cerebral amebiasis due to Entamoeba histolytica are presented. The effect of therapy on the neurological symptoms as well as on the CT findings are described in detail. The multiple intracerebral lesions resolved almost completely and the patient survived without any neurological sequelae.

Amebiasis↗
PubMed1985

Stabilisation of human interferon beta synthesis in Escherichia coli by zinc ions.

Human interferon beta synthesized in Escherichia coli is unstable and toxic for the bacterial cell. Zinc ions are able to stabilise interferon beta in E. coli probably by inhibiting the action of cell internal proteinase(s) which affect the half-life of this foreign protein. As a result up to one order of magnitude more active IFN-beta can be detected in Zn2+-treated E. coli cells.

Cloning, Molecular↗
PubMed1985

[A new 3-dimensional imaging method in computed tomography].

A new imaging method for computerized tomography is presented and some examples are demonstrated. The method is based on the collection of all image data of a chosen block of tissue and enables the examiner to perform multiplanar reconstructions of high quality in any direction, even in oblique planes. In order to achieve a better orientation, the block of tissue can also be visualized at the same time on the reconstruction.

Aged↗
PubMed1985

Multiple intracranial metastases from a prolactin secreting pituitary tumour.

A 28 year old man presented with partial hypopituitarism and signs of a pituitary tumour. A chromophobe adenoma was partially removed by right frontal craniotomy. Seven years later complete hypopituitarism and hyperprolactinaemia were documented, at which time there was no evidence of tumour recurrence of CT scan. The patient was treated with bromocriptine but the pituitary tumour redeveloped a year later. Nine years after the original operation the first metastasis was demonstrated together with very high prolactin levels. The intracranial metastasis, and the pituitary tumour were removed at a second craniotomy following which the prolactin concentration fell. Further metastases developed subsequently and the patient died 12 years after the initial diagnosis. At autopsy multiple metastases were found in the brain, tumour cells were present in the subarachnoid space and in cerebral veins. The pituitary tumour and secondaries were shown by immunocytochemistry to contain prolactin but not ACTH or growth hormone. This appears to be the third well documented case of a metastasizing, prolactin secreting pituitary tumour.

Adenoma, Chromophobe↗
PubMed1985

The rigid spine syndrome--a myopathy of uncertain nosological position.

Four patients meeting the clinical criteria of the rigid spine syndrome are presented; they are one girl with a positive family history and three boys. Clinical and histological findings are discussed in relation to the 14 cases of rigid spine syndrome reported in the literature. The delineations of the syndrome from other benign myopathies with early contractures are discussed suggesting that the rigid spine syndrome probably does not represent a single nosological entity.

Adolescent↗
PubMed1977

Comparative studies of lactate dehydrogenases in lactic acid bacteria. Amino-acid composition of an active-site region and chemical properties of the L-lactate dehydrogenase of Lactobacillus casei, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus acidophilus.

The molecular weight, the amino acid composition and the N-terminal and C-terminal amino acids of two allosteric (Lactobacillus casei, L. curvatus) and two non-allosteric (L. plantarum, L. acidophilus) L-lactate dehydrogenases, purified to homogeneity by affinity chromatography, were determined. The amino acid composition of the only tryptic peptide unequivocally common to the fingerprints of the 4 enzymes is virtually identical with that of the arginine peptide, called Arg6 of the the substratebinding site of the L-lactate dehydrogenase dehydrogenase of several animals. However, the 'essential' cysteine residue 165 is replaced by threonine, as it is in the L-lactate dehydrogenase of lobster. In addition, the 4 bacterial peptides differ by one or two changes in single amino acid residues from each other as well as from those of animals. The data indicate that not only the animal L-lactate dehydrogenases, but also the allosteric and lactate dehydrogenases from bacterial sources may have evolved from a common gene.

Amino Acids↗
PubMed1977

Comparative studies of lactic acid dehydrogenases in lactic acid bacteria. I. Purification and kinetics of the allosteric L-lactic acid dehydrogenase from Lactobacillus casei ssp. casei and Lactobacillus curvatus.

The stability, pH-dependence and kinetic properties of the Mn2+ and FDP-activated NAD-dependent lactic acid dehydrogenases from Lactobacillus casei ssp. casei (ATCC 393) and L. curvatus (DSM 20010) were studied after the enzymes were purified to homogeneity by affinity chromatography. Both enzymes are virtually unidirectional, catalysing efficiency only the reduction of pyruvate. They are similar with respect to the effector requirement and pH-optimum. They differ, however, in their electrophoretic mobility, heat stability, pH-dependence of the Mn2+ requirement and several kinetic properties. It is suggested that most of these differences are caused by differences of the negative charges in the vicinity of the FDP-binding site or the site responsible for the interaction of the subunits of the enzymatically active oligomeres.

Allosteric Regulation↗