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Biomedical subjects

M Wagner

Publications and source records attributed to M Wagner.

At least 235 records · Page 13Linked to original sources
PubMed1999

Localisation of the cell wall-associated phosphodiesterase PhoD of Bacillus subtilis.

The localisation of phosphate-starvation-induced phosphodiesterase PhoD from Bacillus subtilis was studied by analysing processing, release and immunogold labelling of the sections. Although the processing of the pre-protein was extremely slow, the major fraction of PhoD could be detected at the surface of the cell wall. The results indicate that inefficient processing of the translocated pre-protein keeps PhoD in a cell wall-associated location. The uncleaved signal peptide might function as a membrane anchor.

Antibodies, Bacterial↗
PubMed1999

Development of a multiple primer RAPD assay as a tool for phylogenetic analysis in Listeria spp. strains isolated from milkproduct associated epidemics, sporadic cases of listeriosis and dairy environments.

A total of 82 Listeria strains comprising four species were examined by amplification with a multiple primer random amplified polymorphic DNA (RAPD) assay. It was the objective of the study to set up a procedure suitable for analysis of the relationships among strains from milkproduct-associated epidemics, strains from sporadic cases of listeriosis and field strains from dairy products and dairy environments. In a preliminary study, 205 primers, each 10 bp long, were screened for suitability as primers and 44 primers showing reliable and reproducible RAPD patterns at a defined reaction condition were selected. The 82 strains were assigned to 54 RAPD groups positioned in 13 major clusters. Strains isolated during milk product-associated epidemics were found to belong to a single cluster I. Human isolates from sporadic cases of listeriosis predominantly were assigned to four separate clusters. It was found that strains of clinical origin were mainly assigned to other clusters than strains of non-clinical origin.

Animals↗
PubMed1999

Circadian rhythm of motor restlessness and sensory symptoms in the idiopathic restless legs syndrome.

STUDY OBJECTIVES: To determine if motor restlessness in the Restless Legs Syndrome (RLS) shows a circadian rhythm with maximum at night, as previously found for subjective discomfort and periodic limb movements (PLMs), and to correlate RLS peak intensity with the core temperature cycle. DESIGN: Subjects underwent two days of normally timed wakefulness and sleep followed by a night and subsequent day of sleep deprivation. Activity was standardized through modified suggested immobilization tests (mSITs). SETTING: The study was conducted in a laboratory environment with a bedroom equipped for polysomnography during sleep and the mSITs. PATIENTS: Nine patients (mean age 59.8+/-11.3 years [range: 33-72]; 4 males, 5 females) with clinically severe idiopathic RLS. INTERVENTIONS: Patients were monitored with continuous ambulatory activity and core temperature recording. The mSITs were performed every three hours while subjects were awake. During the mSITs, subjective discomfort was measured every 15 minutes while motor restlessness was assessed through activity monitoring. MEASUREMENTS AND RESULTS: Subjective discomfort and motor restlessness increased from a trough in the morning to a maximum at night in the hours following midnight. Peak intensity was found on the falling phase of the core temperature cycle, whose circadian rhythm appeared to be within the normal range for age. CONCLUSIONS: An independent circadian factor modulates the intensity of RLS, which seems to peak on the falling phase of the core temperature cycle. Therefore, the diagnostic criteria that RLS occurs with rest and during the night have independent bases. Furthermore, RLS may be partially controlled by some process or substance whose level varies with the normal circadian rhythm.

Adult↗
PubMed1999

Expression of mitochondrial Apo2.7 molecules and caspase-3 activation in human lymphocytes treated with the ribosome-inhibiting mistletoe lectins and the cell membrane permeabilizing viscotoxins.

BACKGROUND: It is unclear whether expression of newly described mitochondrial Apo2.7 molecules (7A6 antigen) is specific for apoptosis or may also occur in necrosis. METHODS: We incubated human lymphocytes with the apoptosis-inducing mistletoe lectin (ML) I and the cell membrane-permeabilizing viscotoxins (VT), and measured cell death-associated changes by flow cytometry. RESULTS: In ML I-treated lymphocytes, Apo2.7 expression and caspase-3 activation was recognized within 24 h. In VT-treated cells, we observed an Apo2.7 expression with low fluorescence level, while active caspase-3 and DNA fragments (TUNEL) were not detected within 24 h. In these cells, caspase-3 activation was recognized 48 h later. As a major subset of ML-treated cells expressing Apo2.7 molecules did not activated caspase-3, while all caspase-3(+) cells did express Apo2.7, one may suggest that the caspase pathway is activated secondarily to mitochondrial events. CONCLUSIONS: Expression of Apo2.7 is sensitive marker of cell death but may not be specific for apoptosis alone as it can be detected also in cells treated with cell membrane-permeabilizing toxins. On the other hand, this expression may be the consequence of an induction of distinct "death signals" resulting in apoptosis later on.

Apoptosis↗
PubMed1999

Evidence for independent thalamic and cortical sources involved in the generation of the visual 40 Hz response in humans.

Multichannel EEG was recorded to study the gamma-band (30-70 Hz) activity phase-locked to visual checkerboard stimulus onset, in grand-average data of 10 subjects and in three additional individuals. Two different approaches for source analysis were applied to reveal source locations and to determine there time course of activity. Two source regions were separated: one in the depth of the brain, suggested to reflect near thalamic activity, and a second at the visual cortex. Analysis of the source activity in time demonstrated significant different frequencies of the deep at 40 Hz and the cortical source at 37 Hz. There was no consistent phase relation between these source activities. These results contradict the thesis of recurrent thalamocortical activity causing gamma-band oscillations involved in the generation of phase-locked visual checkerboard evoked potentials.

Adult↗
PubMed1999

Cardiac hypertrophy: signal transduction, transcriptional adaptation, and altered growth control.

Cardiac hypertrophy results from the enlargement of cardiac muscle and fibroblast cells. This abnormal pattern of growth can be elicited by a number of hypertrophic agents, such as cytokines and hormones that participate in normal cell-cell signaling events during development. Under conditions yet to be defined, these same signaling molecules can cause hypertrophy of the heart. Intracellular signal transduction pathways appear to be the prime means by which the hypertrophic signal is transduced in cardiomyocytes. There is no evidence that the signal transduction pathways in hypertrophic cardiomyocytes differ from those of normal cardiomyocytes. Perhaps the signal itself is aberrant, mistimed, misplaced, or occurring at non-physiological concentrations. Alternatively, as a quiescent cell, the cardiomyocyte may not be able to respond completely to a growth signal by turning on its proliferative machinery. Three avenues of research are described: (1) the study of the upregulation of the cardiac MLC-2 gene, (2) STAT proteins and activation of angiotensin II, and (3) hypertrophy as a perturbation of cell cycle controls.

Adaptation, Physiological↗
PubMed1999

Acinar-ductal-carcinoma sequence in transforming growth factor-alpha transgenic mice.

Transgenic mice overexpressing transforming growth factor-alpha (TGF-alpha) display an expansion of intrapancreatic fibroblasts and a progressive accumulation of extracellular matrix. This massive fibrosis is associated with an increase in pancreatic size and weight. In parallel, tubular complexes appear that are composed of acinar cells with a decreased height. These acinar cell lose zymogen granules and become transitional cells, which subsequently gain duct cell features. In animals older than one year dysplastic lesions develop, which originate from tubular complexes. Occasionally these dysplastic foci transform to papillary and cystic pancreatic carcinoma. These tumors are positive for the duct-specific antigen Duct-1 and carbonic anhydrase activity indicative of ductal differentiation. Tumors overexpress the epidermal growth factor (EGF)-receptor and p53, but lack K-ras mutations. These data suggest an acinar-ductal-carcinoma sequence in TGF-alpha transgenic mice.

3T3 Cells↗
PubMed1999

Induction of mitochondrial Apo2.7 molecules and generation of reactive oxygen-intermediates in cultured lymphocytes by the toxic proteins from Viscum album L.

We analysed mitochondrial alterations in human lymphocytes incubated with toxins exerting RNA and/or protein synthesis/transport inhibitory activity. We found that all toxins known to affect macromolecule synthesis, such as ricin from Ricinus communis, mistletoe lectin I (ML I) from Viscum album, cycloheximide, actinomycin D, and brefeldin A but also the thionins from Viscum album (viscotoxins; VT) generated reactive oxygen intermediates (ROI) and induced expression of newly described mitochondrial membrane proteins Apo2.7, however, with different kinetics. Apart from a rapid permeabilisation of cell membranes by the VT with swelling of mitochondria, loss of their cristae and ROI generation within 2-4 h, the majority of the cells may have received a distinct 'death signal' resulting in an induction of Apo2.7 molecules within 24 h. In contrast, protein synthesis/transport inhibition may signal for apoptosis within 24 h by decreasing distinct 'survival promotors' which remain to be characterised.

Annexin A5↗
PubMed1999

Characterisation of granulocyte stimulation by thionins from European mistletoe and from wheat.

Thionins are small basic peptides found in different plant species, which are known to exert cytotoxic properties. In addition, previous data indicated an activation of human granulocytes by thionins from European mistletoe (viscotoxins, VT). To extend these latter findings, we investigated the influence of VT and from thionins from wheat flour (purothionin) on human granulocytes by flow cytometry and tried to characterise the involved molecular structures and mechanisms. Phagocytosis was determined by incorporation of FITC-labelled Escherichia coli and respiratory burst by oxidation of dihydrorhodamine 123 to rhodamine 123. VT and purothionin significantly enhanced E. coli-stimulated phagocytosis and respiratory burst at 25 and 250 microgram/ml. Phagocytosis of damaged lymphocytes by granulocytes was detected by electron microscopy in the VT-stimulated (100 microgram/ml) but not in the control cultures. The poly-cationic structure of the intact molecule seems to be crucial, as evidenced by comparison of the burst and phagocytosis-enhancing effects induced by other poly-cationic (protamine sulphate, histone, poly-l-arginine, poly-l-lysine) and poly-anionic (poly-l-glutamic acid) peptides, while pore forming due to amphipathic properties seems to be less important. Ca2+ and Mg2+ could not inhibit VT-enhanced phagocytosis and, thus, could not inhibit binding of VT to granulocytes. In addition, verapamil at low concentrations inhibited VT activity, suggesting the involvement of Ca2+ channels for granulocyte activation by the VT. Similarly, thionins and histones in contrast to protamine sulphate induced cell death of granulocytes at 250 microgram/ml as demonstrated by an enhanced release of reactive oxygen intermediates in unstimulated granulocytes. From these data one may suggest that activity of VT is induced by strong unspecific ionic binding, probably followed by specific receptor binding, and thionins exhibit stimulatory and cytotoxic effects on immune cells, which have to be further characterised.

Antimicrobial Cationic Peptides↗
PubMed1999

Focal adhesions and assessment of cytotoxicity.

Focal adhesions are highly ordered assemblies of transmembrane receptors, extracellular matrix proteins, and a large number of cytoplasmic proteins, including structural proteins, as well as tyrosine kinases, phosphatases, and their substrates. They are now accepted as a prime component of signal transduction. Because focal adhesions also play an important role in cell morphology and migration, it can be argued that their presence is indicative of healthy cells. This has been the reason for several research groups to conclude that biomaterials sustaining focal adhesion assembly are biocompatible. In this study we demonstrate that cells under cytotoxic stress may still be able to retain their focal adhesions. Human umbilical vein endothelial cells at passage 2 were exposed to nickel and zinc ion solutions ranging from 1 to 0.01 mM for 4 and 24 h. Cells were seeded on fibronectin precoated glass slides or in tissue culture quality 96-well plates. MTT conversion with 1 and 0.5 mM nickel and zinc was strongly depressed, indicating that these concentrations are cytotoxic. Proliferative activity was also affected by these concentrations. Cells exposed to zinc typically retracted and detached from the surface, whereas cells exposed to nickel remained on the surface without signs of retraction. Nevertheless, cells exposed to nickel were impaired to reach confluency, which was determined by cadherin-5 expression. All these data indicate that nickel ions at a sufficient concentration influence cells in a cytotoxic way. Despite this apparent cytotoxicity, focal adhesion distribution as visualized by immunofluorescence staining of vinculin was not affected. With zinc the morphological changes were accompanied by apparent fusion of focal adhesions during retraction and finally dissolution. These data indicate that the mere presence of focal adhesions does not allow a reliable statement about the functional status of a cell. On the other hand, when focal adhesions are affected it is an excellent monitor of disturbed cell function.

Cell Adhesion↗
PubMed1999

Further studies on periodic limb movement disorder and restless legs syndrome in children with attention-deficit hyperactivity disorder.

Fourteen consecutive children who were newly diagnosed with attention-deficit hyperactivity disorder (ADHD) and who had never been exposed to stimulants and 10 control children without ADHD underwent polysomnographic studies to quantify Periodic Limb Movements in Sleep (PLMS) and arousals. Parents commonly gave both false-negative and false-positive reports of PLMS in their children, and a sleep study was necessary to confirm their presence or absence. The prevalence of PLMS on polysomnography was higher in the children with ADHD than in the control subjects. Nine of 14 (64%) children with ADHD had PLMS at a rate of >5 per hour of sleep compared with none of the control children (p <0.0015). Three of 14 children with ADHD (21%) had PLMS at a rate of >20 per hour of sleep. Many of the PLMS in the children with ADHD were associated with arousals. Historical sleep times were less for children with ADHD. The children with ADHD who had PLMS chronically got 43 minutes less sleep at home than the control subjects (p = 0.0091). All nine children with ADHD who had a PLMS index of >5 per hour of sleep had a long-standing clinical history of sleep onset problems (>30 minutes) and/or maintenance problems (more than two full awakenings nightly) thus meeting the criteria for Periodic Limb Movement Disorder (PLMD). None of the control children had a clinical history of sleep onset or maintenance problems. The parents of the children with ADHD were more likely to have restless legs syndrome (RLS) than the parents of the control children. Twenty-five of 28 biologic parents of the children with ADHD and all of the biologic parents of the control children were reached for interview. Eight of twenty-five parents of the children with ADHD (32%) had symptoms of RLS as opposed to none of the control parents (p = 0.011). PLMS may directly lead to symptoms of ADHD through the mechanism of sleep disruption. Alternative explanations for the association between ADHD and RLS/PLMS are that they are genetically linked, they share a common dopaminergic deficit, or both.

Arousal↗
PubMed1999

Various functions of selenols and thiols in anaerobic gram-positive, amino acids-utilizing bacteria.

Electron transfer reactions for the reduction of glycine in Eubacterium acidaminophilum involve many selenocysteine (U)- and thiol-containing proteins, as shown by biochemical and molecular analysis. These include an unusual thioredoxin system (-CXXC-), protein A (-CXXU-) and the substrate-specific protein B of glycine reductase (-UXXCXXC-). Most probably a selenoether is formed at protein B by splitting the C-N-bond after binding of the substrate. The carboxymethyl group is then transferred to the selenocysteine of protein A containing a conserved motif. The latter protein acts as a carbon and electron donor by giving rise to a protein C-bound acetyl-thioester and a mixed selenide-sulfide bond at protein A that will be reduced by the thioredoxin system. The dithiothreitol-dependent D-proline reductase of Clostridium sticklandii exhibits many similarities to protein B of glycine reductase including the motif containing selenocysteine. In both cases proprotein processing at a cysteine residue gives rise to a blocked N-terminus, most probably a pyruvoyl group. Formate dehydrogenase and some other proteins from E. acidaminophilum contain selenocysteine, e.g., a 22 kDa protein showing an extensive homology to peroxiredoxins involved in the detoxification of peroxides.

Amino Acids↗
PubMed1999

The role of higher-order motor areas in voluntary movement as revealed by high-resolution EEG and fMRI.

In the human motor cortex structural and functional differences separate motor areas related to motor output from areas essentially involved in higher-order motor control. Little is known about the function of these higher-order motor areas during simple voluntary movement. We examined a simple finger flexion movement in six healthy subjects using a novel brain-imaging approach, integrating high-resolution EEG with the individual structural and functional MRI. Electrical source reconstruction was performed in respect to the individual brain morphology from MRI. Highly converging results from EEG and fMRI were obtained for both executive and higher-order motor areas. All subjects showed activation of the primary motor area (MI) and of the frontal medial wall motor areas. Two different types of medial wall activation were observed with both methods: Four of the subjects showed an anterior type of activation, and two of the subjects a posterior type of activation. In the former, activity started in the anterior cingulate motor area (CMA) and subsequently shifted its focus to the intermediate supplementary motor area (SMA). Approximately 120 ms before the movement started, the intermediate SMA showed a drop of source strength, and simultaneously MI showed an increase of source strength. In the posterior type, activation was restricted to the posterior SMA. Further, three of the subjects investigated showed activation in the inferior parietal lobe (IPL) starting during early movement preparation. In all subjects showing activation of higher-order motor areas (anterior CMA, intermediate SMA, IPL) these areas became active before the executive motor areas (MI and posterior SMA). We suggest that the early activation of the anterior CMA and the IPL may be related to attentional functions of these areas. Further, we argue that the intermediate part of the SMA triggers the actual motor act via the release of inhibition of the primary motor area. Our results demonstrate that a noninvasive, multimodal brain imaging technique can reveal individual cortical brain activity with high temporal and spatial resolution, independent of a priori physiological assumptions.

Adult↗
PubMed1999

Spontaneous uprighting of permanent tooth germs after elimination of local eruption obstacles.

Four clinical cases are presented to demonstrate the self-correcting potential of aberrant tooth germs after the elimination of eruption obstacles (in 2 cases cysts, in 2 other cases severely infraoccluded primary teeth). In the case of the submerging deciduous teeth, the tilted adjacent teeth were orthodontically uprighted after the surgical procedure. Possible causative mechanisms are discussed.

Bicuspid↗