Search PubMed⌕ Search

Biomedical subjects

M Wagner

Publications and source records attributed to M Wagner.

At least 433 records · Page 24Linked to original sources
PubMed1995

Purification and characterization of threonine dehydrogenase from Clostridium sticklandii.

Threonine dehydrogenase from Clostridium sticklandii has been purified 76-fold from cells grown in a defined medium to a homogeneous preparation of 234 units.mg-1 protein. Purification was obtained by chromatography on Q-Sepharose fast flow and Reactive green 19-Agarose. The native enzyme had a molecular mass of 67 kDa and consisted of two identical subunits (33 kDa each). The optimum pH for catalytic activity was 9.0. Only L-threo-threonine, DL-beta-hydroxynorvaline and acetoin were substrates; only NAD was used as the natural electron acceptor. The apparent Km values for L-threonine and NAD were 18 mM and 0.1 mM, respectively. Zn2+, Co2+ and Cu2+ ions (0.9 mM) inhibited enzyme activity. The N-terminal amino acid sequence revealed similarities to the class of non-metal short-chain alcohol dehydrogenases, whereas the threonine dehydrogenase from Escherichia coli belongs to the class of medium chain, zinc-containing alcohol dehydrogenases.

Alcohol Oxidoreductases↗
PubMed1995

Comparison of realistically shaped boundary-element and spherical head models in source localization of early somatosensory evoked potentials.

Source localizations of early somatosensory evoked potentials and electrical potentials produced by dipoles in the region of the central sulcus were computed using realistically shaped boundary-element head models (BEM) and compared to localizations obtained using 3-shell spherical models. Realistically shaped 3-shell boundary-element-models were constructed on the basis of the individual anatomy obtained from 3D-MR-tomography in 6 subjects. Spherical head models were fitted to the actual locations of the electrodes and to the surface of the heads, respectively. Source locations calculated within the spherical head models differed by an average of 4 mm (range: 2 to 7 mm) with respect to the 3-shell BEM, taking into account the limited accuracy of this model. This mislocation was most prominently due to deeper source locations predicted using a spherical head model and caused by incorrect modelling of the geometry of the heads, although sources were located in a favourable region of the heads.

Adult↗
PubMed1995

Effect of age and disease duration on parkinsonian motor scores under levodopa therapy.

One hundred and fifty patients suffering from Parkinson's disease were analysed for the expression of the motor symptoms during optimum response to levodopa therapy (subscale III of the Unified-Parkinson's Disease Rating Scale). Patients were grouped according to age (< or = 64, 65-74, > or = 75 years). Disease duration and daily levodopa dosage were similar in the three groups. Pooled residual scores for posture and gait impairment (PGI), tremor (T), rigidity (R) and distal motor impairment (DMI; hand and foot movements) increased with age (Kruskal-Wallis ANOVA). The parkinsonian scores were significantly higher than the scores of 150 age-matched normal controls (Mann-Whitney U test). The differences between the patients' scores and the scores of the age-matched controls increased with age. In spite of a significant increase in the daily levodopa dosage with disease duration (linear regression), PGI aggravated age-dependently, and DMI age-independently with symptom duration (Spearman rank correlation). In contrast, T and R did not increase with disease duration.

Adult↗
PubMed1995

[The edge-centroid relation and overbite in Class-II.1 patients. A follow-up study].

This follow-up study evaluates lateral skull radiographs and jaw casts taken prior to treatment, at the end of treatment, and after a control period of one at a minimum of 25 orthodontically treated children, 14 males and 11 females, who had an Angle class II, 1 malocclusion and a deep overbite with the lower incisors impinging upon the palatal gingiva. The study's object of interest was the anterior-posterior relationship of the lower incisor edge to the upper incisor root centroid (i.e., the "edge-centroid relationship", Houston [7]). Its intent was to evaluate the correlation between edge-centroid relationship and an overbite relapse respectively when viewed in relation to the developments which take place in the dental and skeletal variables during the course of overbite reduction. The edge-centroid relationship was found, to present an interesting screening method in diagnosing class II, 1 cases, and, although with some reservations, the relationship is also useful in planning treatment.

Adolescent↗
PubMed1995

Menstrual cycle affects functional cerebral asymmetries.

Cerebral lateralization in females is probably modulated by the menstrual cycle such that a part of hemispheric asymmetries are diminished with an increase of the steroids estrogen and progesterone during the follicular and luteal phase and enhanced with steroid decreases during the menstrual phase. However, previous data were contradictory with regard to the hemispheric side of modulation and could not analyze which steroid is mainly responsible for cycle dependent lateralization shifts. Therefore, in the present study estrogen and progesterone changes were assessed separately and related to changes in cerebral asymmetry. Plasma levels of estrogen and progesterone were measured once during luteal and once during menstrual cycle phase while 20 females subjects performed a verbal and a figural lateralized matching task. The results showed a significant cycle phase x lateralization interaction for the right hemisphere dominated figural comparison task but not for the left hemispheric lexical condition. Although the lateralization was modulated by the menstrual cycle, a within-subject regression analysis demonstrated that the asymmetry shift was not under direct influence of estrogen or progesterone. Thus, the present study provides further empirical support for cycle dependent alterations in lateralization but makes it unlikely that this effect is directly caused by estrogen or progesterone plasma level variations.

Adult↗
PubMed1995

Cold acclimation and endurance training in guinea pigs: changes in lung, muscle and brown fat tissue.

The effects of an intermittent high intensity stimulus (running) or a chronic low intensity stimulus (cold acclimation) of oxidative metabolism on maximal oxygen uptake (VO2,max), lung O2 diffusing capacity (DLO2) and skeletal muscle as well as fat tissue mitochondrial content in growing guinea pigs are described. Young male guinea pigs were assigned to three experimental groups (n = 5): control (C), endurance trained (T; at 70% VO2max) or cold acclimated (CA; 5-7 degrees C) for six weeks. Animals were sacrificed at the end of the experimental period and tissue for morphometric analysis of the lung, muscle and interscapular fat was sampled. T and CA animals significantly increased weight specific VO2max by 23% and 29%, respectively. Despite a significant increase in absolute lung volume in T (+10%) and in weight specific lung volume in CA (+20%) neither absolute nor weight specific DLO2 was significantly affected by the experimental treatments. In trained animals the total volume of mitochondria remained unchanged in samples representative for the entire musculature but was significantly increased in M. vastus intermedius (+72%). Intramyocellular lipids increased significantly both in M. vastus intermedius (+244%) as well as in the whole body musculature (+164%). Cold acclimation increased the mitochondrial content of the interscapular fat pad by approximately 20-fold but had no effect on total mitochondrial volume in muscle. We conclude that the increase in oxygen demand resulting from exercise training or from cold acclimation could be accomodated by the existing lung diffusing capacity and did not induce a global change of oxidative capacity in skeletal muscle tissue in growing guinea pigs. Exercise training caused oxidative capacity to increase only in a locomotor muscle activated during running whereas cold acclimation greatly increased interscapular fat tissue oxidative capacity.

Acclimatization↗
PubMed1995

Tellurite specifically affects squalene epoxidase: investigations examining the mechanism of tellurium-induced neuropathy.

A peripheral neuropathy characterized by a transient demyelinating/remyelinating sequence results when young rats are fed a tellurium-containing diet. The neuropathy occurs secondary to a systemic block in cholesterol synthesis. Squalene accumulation suggested the lesion was at the level of squalene expoxidase, a microsomal monooxygenase that uses NADPH cytochrome P450 reductase to receive its necessary reducing equivalents from NADPH. We have now demonstrated directly specificity for squalene epoxidase; our in vitro studies show that squalene epoxidase is inhibited 50% in the presence of 5 microM tellurite, the presumptive in vivo active metabolite. Under these conditions, the activities of other monooxygenases, aniline hydroxylase and benzo(a)pyrene hydroxylase, were inhibited less than 5%. We also present data suggesting that tellurite inhibits squalene epoxidation by interacting with highly susceptible -SH groups present on this monooxygenase. In vivo studies of specificity were based on the compensatory response to feeding of tellurium. Following tellurium intoxication, there was up-regulation of squalene epoxidase activity both in liver (11-fold) and sciatic nerve (fivefold). This induction was a specific response, as demonstrated in liver by the lack of up-regulation following exposure to the nonspecific microsomal enzyme inducer, phenobarbital. As a control, we also measured the microsomal monooxygenase activities of aniline hydroxylase and benzo(a)pyrene hydroxylase. Although they were induced following phenobarbital exposure, activities of these monooxygenases were not affected following tellurium intoxication, providing further evidence of specificity of tellurium intoxication for squalene epoxidase.

Aniline Hydroxylase↗
PubMed1995

Reduced copper enzyme activities in blood cells of children with cystic fibrosis.

Cystic fibrosis patients are at risk for nutrient deficiencies from malabsorption related to exocrine pancreatic insufficiency. This research examined the copper homeostasis of children with cystic fibrosis. Our objective was to measure cytochrome oxidase and copper-zinc superoxide dismutase activities in mononuclear cells, neutrophils, and erythrocytes of adolescents with cystic fibrosis, as well as plasma copper and ceruloplasmin. Thirteen adolescents with pancreatic insufficiency caused by cystic fibrosis were compared with 10 age- and sex-matched control subjects. Serum copper concentrations and ceruloplasmin measurements were not significantly different between the two groups. Cytochrome oxidase activity was significantly lower in the mononuclear cells and copper-zinc superoxide dismutase activity was significantly lower in the neutrophils and erythrocytes of the cystic fibrosis group. Other measures of trace element status such as hemoglobin concentration, serum ferritin, serum zinc, glutathione peroxidase activity, and manganese superoxide dismutase activity were not different between the two groups. Reductions in the activity of two copper-dependent enzymes suggest abnormal copper homeostasis in this population.

Adolescent↗
PubMed1995

Coordinate system matching for neuromagnetic and morphological reconstruction overlay.

The overlay of functional and morphological images is an essential tool for advanced and improved functional diagnosis showing the correlation between spatial structures or lesions and functional areas. We present an improved coordinate system matching technique. The well known method of three orthogonal coils combined in one coilset for an angular-independent measure is validated for the use of first- or higher order gradiometers instead of magnetometers. The coilset localization procedure was modified with lock-in detection and current feedback for better long range sensitivity. Real measurements with the 31-channel Philips-MEG system have been carried out. A very good localization accuracy below the measuring area with deviations below 2 mm was found. For coordinate system matching, a 3-D cursor with surface images from segmented MR-data was implemented and an optimized, weighted least squares fit transformation algorithm between functional and morphological systems was developed. The resulting transformations consist of weighted shifts and best-fit rotations and lead to deviations of marker positions in the mm range, depending mainly on the spatial accuracy of the marker fixation.

Algorithms↗
PubMed1995

Sensitivity of Porphyromonas and Prevotella species in liquid media to argon laser.

The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all "black-pigmented bacteria," BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of periodontal disease. Non-black-pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for periodontal infections. Cell suspensions were irradiated with an argon laser at fluences of 20-200 J/cm2. When cultured in hemin-supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non-black-pigmented bacteria were much less sensitive to irradiation than BPB.

Argon↗
PubMed1995

Antigenic properties and immunoelectron microscopic localization of Mycobacterium fortuitum beta-lactamase.

Mycobacterium fortuitum is a fast-growing Mycobacterium species which produces a beta-lactamase involved in the intrinsic resistance of the microorganism to beta-lactam antibiotics. An anti-beta-lactamase serum against the purified enzyme was raised in rabbits. Antibody binding was specific for native beta-lactamase, and enzyme activity was partially inhibited by the serum; furthermore, cross-reactions with denatured class A beta-lactamases were observed. This serum was used as a probe in immunogold labeling for the localization of the cell-bound beta-lactamase in both the low-level producer ATCC 19542 (parental strain) and the overproducer mutant D316. By the combination of preembedding immunogold labeling and replica technique, it was shown that the beta-lactamase was uniformly distributed on the whole external cell surface, where it appeared to be associated with a Tween 80-removable capsule-like material. Compared with the parental strain, a much higher level of expression of surface enzyme was observed in strain D316. Surface labeling was more intense in the stationary phase of growth than in exponentially growing cells. The data obtained are interpreted in the context of the intrinsic resistance of M. fortuitum to beta-lactam antibiotics.

Antigens, Bacterial↗
PubMed1995

The abundance of Zoogloea ramigera in sewage treatment plants.

Zoogloea ramigera has long been considered the typical activated sludge bacterium responsible for the formation of activated sludge flocs. On the basis of the results of a comparative sequence analysis, we designed three oligonucleotide probes complementary to characteristic regions of the 16S rRNAs of Z. ramigera ATCC 19544T (T = type strain) and two misclassified strains, Z. ramigera ATCC 25935 and ATCC 19623. Dissociation temperatures were determined, and probe specificities, as well as the potential of probes for whole-cell hybridization, were evaluated by using numerous reference organisms. Several activated sludge samples were examined with these probes by using both the in situ and dot blot hybridization methods. Only the type strain probe hybridized to cells that accumulated in the typical branched gelatinous matrices, the so-called Zoogloea fingers. This probe revealed cells in most of the activated sludge samples studied. We found that relatively high levels of Z. ramigera cells (up to approximately 10% of the total number of cells) and typical morphology tended to be linked to overloading of sewage plants. The probe directed to rejected type strain Z. ramigera ATCC 19623 bound to only a few cells. Cells that reacted with the probe complementary to Z. ramigera ATCC 25935, which was originally isolated from a trickling filter, were not observed in activated sludge.

Base Sequence↗
PubMed1995

Comparative studies on vascular endothelium in vitro. 3. Effects of cytokines on the expression of E-selectin, ICAM-1 and VCAM-1 by cultured human endothelial cells obtained from different passages.

Endothelial cells (EC) are very responsive to proinflammatory cytokines, e.g. interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha), as well as to bacterial lipopolysaccharide. EC are stimulated by these substances to secrete chemotactic factors and to increase expression of cell adhesion molecules (CAM), leading to dramatically altered interactions with leukocytes, e.g. granulocytes and monocytes. In these interactions E-selectin, ICAM-1 and VCAM-1 are known to play an important role, as they are presented by the EC and interact with corresponding ligands on the white blood cell membranes. These adhesion molecules have been studied worldwide in a variety of in vitro experiments using cultured EC. Different passages and mixtures of passages have been used in these experiments, often without any regard to the comparability of the results. In this study the expression of E-selectin, ICAM-1 and VCAM-1 on cultured human umbilical vein EC (HUVEC) obtained from different passages (passages 1-6) was studied after 4, 8 and 24 h of exposure to IL-1 beta and TNF alpha. In previous studies, we have shown that IL-1 beta and TNF alpha increase the expression of E-selectin and ICAM-1 on the cytoplasmatic membranes of HUVEC and human adult EC from the saphenous vein and femoral artery in a similar fashion. Using a comparative quantitative cell enzyme immunoassay, we found that the expression of the adhesion molecules was significantly reduced with increasing passages. There was also a decreased persistence of CAM comparing different periods of stimulation between 6 and 24 h in the different passages. These data indicate that the number of passages plays an important role in the expression of adhesion molecules on EC. The results are relevant for the meaningful planning of comparative in vitro studies on EC presentation of CAM.

Cells, Cultured↗
PubMed1995

Effects of cytokines on the expression of cell adhesion molecules by cultured human omental mesothelial cells.

Cultured mesothelial cells (HOMES) are very responsive to the proinflammatory cytokines, interleukin (IL)-1 and tumor necrosis factor-alpha (TNF-alpha). E-selectin, ICAM-1 and VCAM-1 are known to play an important role, because they are presented by diverse cell types, for example endothelial cells (ECs), and interact with co-responding ligands on white blood cell membranes. In this study, the expression of ICAM-1, VCAM-1, E-selectin as well as PECAM-1 on cultured HOMES was studied over 5, 24, 48 and 72 h exposure to IL-1 beta, interferon-gamma and TNF-alpha. In previous studies we have shown that IL-1 beta and TNF-alpha increase the expression of ICAM-1, E-selectin and VCAM-1 on the cytoplasmatic membranes of HUVECs, HSVECs and HAFECs (ECs from human umbilical vein, saphenous vein and femoral artery, respectively). Using a comparative quantitative cell enzyme immunoassay, we found that expression of the adhesion molecules ICAM-1 and VCAM-1 was significantly increased on HOMES in a dose- and time-dependent manner, compared to nonstimulated cells. Thus, ICAM-1 increased dramatically after 5 h incubation with TNF-alpha. Values of about 450% of the control level were measured. VCAM-1 was similarly stimulated after 24 h incubation with the same cytokine, although its level of expression was significantly lower than that of ICAM-1. In contrast to findings in the literature, VCAM-1 was not found to be expressed constitutively. E-selectin was neither constitutively expressed nor markedly inducible on HOMES. Only weak expression was found after 24 h incubation with high-dose IL-1 beta. PECAM-1 was expressed constitutively, as became evident in antibody dilution studies. These data indicate that HOMES respond to inflammatory stimuli, in some ways in a similar fashion to vascular endothelial cells, but also show a specific pattern of antigen presentation. The results are important for a better understanding of inflammatory processes in serous cavities. The data are also relevant for the improvement of antithrombogenous surfaces of the lumina of vascular prostheses by cell seeding.

Cell Adhesion Molecules↗