Showing papers by "University of Düsseldorf published in 1995"

In vivo evidence of structural brain asymmetry in musicians

Abstract: Certain human talents, such as musical ability, have been associated with left-right differences in brain structure and function. In vivo magnetic resonance morphometry of the brain in musicians was used to measure the anatomical asymmetry of the planum temporale, a brain area containing auditory association cortex and previously shown to be a marker of structural and functional asymmetry. Musicians with perfect pitch revealed stronger leftward planum temporale asymmetry than nonmusicians or musicians without perfect pitch. The results indicate that outstanding musical ability is associated with increased leftward asymmetry of cortex subserving music-related functions.

The Ontogeny of Human Gyrification

Abstract: During development the human cortex changes from a smooth lissencephalic structure to one that is highly convoluted. Increases in the degree of cortical folding are associated with brain size only for the first part of brain growth; during the second half, differences in cortical folding match those of brain size, resulting in no change in the degree of folding. When the degree of cortical folding is studied as a function of age, a brief postnatal overshoot, an effect of brain size, is observed. The analysis suggests that the mechanical hypothesis of cortical buckling can best explain the degree of cortical folding, but that other hypotheses, like gyrogenesis, are required to explain the placement and orientation of sulci. The adult asymptote in degree of cortical folding is associated with the onset and disappearance of single subplate lamina, suggesting that subplate:cortical plate associations should be examined as causal for gyrification. Areas whose sulci differ in length between the two hemispheres have similar degrees of convolutedness, supporting interpretations that the sizes of gyri are asymmetric in the two hemispheres. The ontogenetic data support the thesis that human cortical proportions evolved when the brain enlarged in size and that the process was not one of neoteny.

Treatment of symptomatic diabetic peripheral neuropathy with the anti-oxidant alpha-lipoic acid. A 3-week multicentre randomized controlled trial (ALADIN Study).

Abstract: Anti-oxidant treatment has been shown to prevent nerve dysfunction in experimental diabetes mellitus, thus providing a rationale of potential therapeutic value for diabetic patients. The effects of the anti-oxidant alpha-lipoic acid (thioctic acid) were studied in a 3-week multicentre, randomized, double-blind placebo-controlled trial (Alpha-Lipoic Acid in Diabetic Neuropathy; ALADIN) in 328 non-insulin-dependent diabetic patients with symptomatic peripheral neuropathy who were randomly assigned to treatment with intravenous infusion of alpha-lipoic acid using three doses (1200, 600, or 100 mg ALA) or placebo (PLAC). Neuropathic symptoms (pain, burning, paraesthesiae, and numbness) were scored at baseline and at each visit (days 2-5, 8-12, and 15-19) prior to infusion. In addition, the Hamburg Pain Adjective List, a multidimensional specific pain questionnaire, and the Neuropathy Symptom and Disability Scores were assessed at baseline and day 19. According to the protocol 260 (65/63/66/66) patients completed the study. The total symptom score in the feet decreased from baseline to day 19 by -4.5 +/- 3.7 (-58.6%) points (mean +/- SD) in ALA 1200, -5.0 +/- 4.1 (-63.5%) points in ALA 600, -3.3 +/- 2.8 (-43.2%) points in ALA 100, and -2.6 +/- 3.2 (-38.4%) points in PLAC (ALA 1200 vs PLAC: p = 0.003; ALA 600 vs PLAC: p < 0.001). The response rates after 19 days, defined as an improvement in the total symptom score of at least 30%, were 70.8% in ALA 1200, 82.5% in ALA 600, 65.2% in ALA 100, and 57.6% in PLAC (ALA 600 vs PLAC; p = 0.002). The total scale of the Pain Adjective List was significantly reduced in ALA 1200 and ALA 600 as compared with PLAC after 19 days (both p < 0.01). The rates of adverse events were 32.6% in ALA 1200, 18.2% in ALA 600, 13.6% in ALA 100, and 20.7% in PLAC. These findings substantiate that intravenous treatment with alpha-lipoic acid using a dose of 600 mg/day over 3 weeks is superior to placebo in reducing symptoms of diabetic peripheral neuropathy, without causing significant adverse reactions.

Nitric oxide induces apoptosis in mouse thymocytes.

Abstract: Nitric oxide (NO) produced at high concentrations by the inducible NO synthase is an important effector molecule involved in immune regulation and defense. We have examined whether NO represents a signal for triggering apoptosis in thymocytes. Freshly isolated thymocytes were incubated with different chemical NO donors for various intervals. Apoptosis was determined by detection of DNA strand breaks with in situ nick translation. All NO donors induced thymocyte apoptosis with 30% positive thymocytes vs 10% in controls after 8 h. Apoptosis was prevented by addition of ZnSO4. Short-term pre-exposure to NO resulted in protection from apoptosis induced by glucocorticoids comparable with the protective effect of heat shock. Flow cytometry revealed that NO treatment as well as heat shock or dexamethasone incubation is accompanied by reduction in the CD4+ CD8+ thymocyte subpopulation. Apoptosis induction was accompanied by increased expression of p53, as detected by PCR analysis 2 h after NO donor addition. In vivo treatment of mice with endotoxin results in increased thymic apoptosis. Focal apoptosis was found to occur in close proximity to blood vessels 18 h after LPS treatment. Capillary endothelium and dendritic cells adjacent to apoptotic foci were found to stain strongly for inducible NO synthase expression. Furthermore, in an in vitro experiment using cocultures of thymocytes with LPS/cytokine-activated endothelial cells expressing inducible NO synthase, a significantly increased rate of thymocyte apoptosis was found, and this could be prevented completely by inhibiting NO production. Addition of dexamethasone to these cocultures did not lead to a further increase in the percentage of apoptotic thymocytes, underlining the protective effect of NO on dexamethasone-induced apoptosis.

Non-Linear Gaussian Filters Performing Edge Preserving Diffusion

Abstract: This paper presents a new diffusion method for edge preserving smoothing of images. In contrast to other methods it is not based on an anisotropic modification of the heat conductance equation, rather on a modification of the way the solution of the heat conductance equation is obtained by convolving the initial data with a Gaussian kernel. Hence the method uses simple non-linear modifications of Gaussian filters, thus avoiding iteration steps and convergence problems. A chain of three to five filters with suitable parameters provides excellent smoothing of fine image details without destroying the coarser structures. The size and contrast of the eliminated details can be selected. The choice of the parameters is not critical and the edges are not displaced when changing the scale. The filter stages can be implemented efficiently on almost any parallel hardware architecture.

Plaque Ulceration and Lumen Thrombus Are the Main Sources of Cerebral Microemboli in High-grade Internal Carotid Artery Stenosis

Abstract: Background and Purpose Previous work has shown that rates of cerebral microemboli downstream of high-grade internal carotid artery stenosis are higher in recently symptomatic compared with asymptomatic patients. In addition, microembolic rates decline after carotid endarterectomy. We conducted a prospective investigation of 40 consecutive asymptomatic or recently symptomatic patients undergoing carotid endarterectomy for 70% to 95% internal carotid artery stenosis to determine the relationship between microembolic rate and pathoanatomic features of the carotid plaque. Methods Transcranial Doppler monitoring including automated emboli detection was performed preoperatively to assess the rate of cerebral microemboli of the ipsilateral middle cerebral artery. The corresponding endarterectomy specimens were evaluated histologically with respect to the occurrence of plaque fissuring, intraplaque hemorrhage, plaque ulceration, or intraluminal thrombosis. Results There were strong associations between plaque ulc...

Isolation and Characterization of the Proton-translocating NADH:ubiquinone Oxidoreductase from Escherichia coli

Abstract: The proton-translocating NADH:ubiquinone oxidoreductase (complex I) was isolated from Escherichia coli by chromatographic steps performed in the presence of an alkylglucoside detergent at pH 6.0. The complex is obtained in a monodisperse state with a molecular mass of approximately 550000 Da and is composed of 14 subunits. The subunits were assigned to the 14 genes of the nuo operon, partly based on their N-terminal sequences and partly on their apparent molecular masses. The preparation contains one noncovalently bound FMN/molecule. At least two binuclear (N1b and N1c) and three tetra-nuclear (N2, N3 and N4) iron-sulfur clusters were detected by EPR in the preparation when reduced with NADH. Their EPR characteristics remained mostly unaltered during the isolation process. After reconstitution in phospholipid membranes, the preparation catalyses piericidin-A-sensitive electron transfer from NADH to ubiquinone-2 with Km values similar to those of complex I in cytoplasmic membranes but with only 10% of the Vmax value. The isolated complex I was cleaved into three fragments when the pH was raised from 6.0 to 7.5 and the detergent exchanged to Triton X-100. One of these fragments is a water-soluble NADH dehydrogenase fragment which is composed of three subunits bearing at least four iron-sulfur clusters (N1b, N1c, N3 and N4) that can be reduced with NADH, one of them bearing FMN. The second, amphipathic, fragment, which is presumed to connect the NADH dehydrogenase fragment with the membrane, contains four subunits and at least one EPR-detectable iron-sulfur cluster whose spectral properties are reminiscent of the eucaryotic cluster N2. The third membrane fragment is composed of seven homologues of the mitochondrially encoded subunits of the eucaryotic complex I. This subunit arrangement coincidences to some extent with the order of the genes on the nuo operon. A topological model of the E. coli complex I is proposed.

Lymphocytic Infiltration and Expression of Intercellular Adhesion Molecule-1 in Photochemically Induced Ischemia of the Rat Cortex

Abstract: The contribution of the immune system to the pathogenesis of ischemic lesions is still uncertain. We have analyzed leukocyte infiltration in photochemically induced focal ischemia of the rat parietal cortex by immunocytochemistry. Between 1 and 2 days after photothrombosis, CD5+ T cells adhered to subpial and cortical vessels and infiltrated the ischemic lesion prior to macrophages. By day 3 numerous T cells and some macrophages, whose number increased further between day 3 and day 7, had infiltrated the border zone around the lesion sparing the center. In addition, CD5-/CD8+ lymphocytes that probably represent natural killer cells were found. Intercellular adhesion molecule-1 (ICAM-1) was expressed on endothelial cells on days 1 and 2 and in the border zone on infiltrating leukocytes from day 3 to day 7. Starting on day 7, macrophages infiltrated the core of the lesion to remove debris. When the entire lesion was covered by macrophages at day 14, the number of T cells had decreased and ICAM-1 immunoreactivity was no longer found in or around the infarct. In conclusion, our study shows that ischemic lesions can lead to a local immune reaction in the CNS. Thus, blocking of lymphocyte-derived cytokines or cell adhesion molecules may provide a new approach to confining the sequelae of stroke.

Effects of tumour necrosis factor alpha (TNFα) on glucose transport and lipid metabolism of newly-differentiated human fat cells in cell culture

Abstract: Tumour necrosis factor alpha (TNFα) has been found to cause a delipidation of fat cells and a decrease of the adipose tissue mass. In the present study, we tried to elucidate some of the mechanisms responsible for this phenomenon by investigating the action of TNFα on specific pathways which are involved in lipid storage. Cultured stromal cells from human adipose tissue were induced to differentiate into adipose cells by exposure to adipogenic factors and subsequently used for studying the effects of TNFα on fat cell metabolism. Presence of 5 nmol/l TNFα for 24 h resulted in a complete loss of the stimulatory effect of insulin on 2-deoxy-glucose transport. This inhibitory action was paralleled by a decrease of GLUT4 protein and mRNA levels. The amount of cellular GLUT4 protein was reduced by 49 ± 3 % after a 24-h exposure and by 82 ± 18 % after a 72-h exposure to 5 nmol/1 TNFα. GLUT4 mRNA was almost undetectable after a 24-h incubation with 5 nmol/l TNFα In a similar time-dependent manner, TNFα dramatically reduced the lipoprotein lipase mRNA content of the cells. Furthermore, incubation of cultured human fat cells with TNFα resulted in a marked dose-dependent stimulation of lipolysis, assessed by glycerol release, by up to 400 % above controls, which became apparent after a 6-h exposure at the earliest. These data suggest that TNFα induces a catabolic state in human adipose tissue which includes a loss of the stimulatory effect of insulin on glucose transport. These multiple actions of TNFα may contribute to the loss of adipose tissue observed during cachexia in man.

Hemispheric asymmetry of transcallosal inhibition in man

Abstract: The transcallosal connecting fibres linking corresponding projection areas of the same muscles of the right and left primary motor cortex may play an important role in control of unilateral movements. It appears that they have mainly inhibitory effects. This was further evaluated by transcranial magnetic stimulation using two focal coils placed on the optimal positions, i.e. the positions with the lowest thresholds at the motor representation areas of the first dorsal interosseous muscle of the left and right sides. A conditioning stimulus was given to one hemisphere 10 ms prior to the test stimulus at the opposite hemisphere. The inhibition was evaluated as relative amplitude reduction. Eleven normal right-handed subjects and 11 normal left-handed subjects participated in this study. Handedness was evaluated by the Oldfield inventory. It was found that in right-handers the inhibition after stimulation of the "dominant" left hemisphere was more marked than after stimulation of the "non-dominant" right hemisphere. In contrast, the group of left-handed subjects showed inhomogeneous findings with either right- or left-side predominant inhibition. It is concluded that not handedness but hemispheric dominance contributes to the laterality of inhibition. The results point to a superior role of the language-dominant hemisphere in governing inter-hemispheric control of motor cortical connections, supporting the view that the "language-dominant" hemisphere is also "motor dominant".

Identification of novel HXT genes in Saccharomyces cerevisiae reveals the impact of individual hexose transporters on qlycolytic flux

Abstract: Summary In Saccharomyces cerevisiae, hexose uptake is mediated by HXT proteins which belong to a superfamily of monosaccharide facilitators. We have identified three more genes that encode hexose transporters (HXT5, 6, 7). Genes HXT6 and HXT7 are almost identical and located in tandem 3′ adjacent to HXT3 on chromosome IV. We have constructed a set of congenic strains expressing none or any one of the seven known HXT genes and followed growth and flux rates for glucose utilization. The hxt null strain does not grow on glucose, fructose or mannose, and both glucose uptake and flux rate were below the detection level. Expression of either HXT1, 2, 3, 4, 6 or 7 is basically sufficient for aerobic growth on these sugars. In most of the constructs, glucose was the preferred substrate compared to fructose or mannose. There is a considerable variation in flux and growth rates with 1% glucose, dependent on the expression of the individual HXT genes. Expression of either HXT2, 6 or 7 in the null background is sufficient for growth on 0.1% glucose, while growth of strains with only HXT1, 3 or 4 requires higher (≥1%) glucose concentrations. These results demonstrate that individual HXT proteins can function independently as hexose transporters, and that most of the metabolically relevant HXT transporters from S. cerevisiae have been identified.

Membrane Chromatography—An Integrative Concept in the Downstream Processing of Proteins

Abstract: Membrane chromatography was introduced as an integrative technology for the purification of proteins several years ago. The main feature of chromatographic separations based on membranes is the absence of pore diffusion, which is the main transport resistance in conventional column chromatography using porous particles. This is achieved by attaching the active ligands to the inner surface of the through-pores of microfiltration membranes, where mass transport takes place mainly by convective flow, thus reducing the transport limitations from pore to film diffusion. In combination with a low pressure drop across a membrane, very high volumetric flows are possible in a membrane-based purification step; thus, the time requirement of a complete chromatographic cycle is reduced. The method is characterized by fast processing at preserved or even increased resolution compared to standard chromatography on particulate materials. Since its introduction, many successful applications of membrane chromatography have been described. Additionally, theoretical analysis has been performed, which has significantly helped to understand present and visualize future applications of this technology. In this review, the fundamental theoretical considerations from the actual literature are described, and then the applications of membrane-based separation processes are presented. We have attempted to demonstrate the usefulness of this new technology in the purification of many interesting proteins.

Structure and properties of plasma-nitrided stainless steel

Abstract: A series of plasma-nitriding experiments has been conducted on AISI 304L austenitic stainless steel at temperatures ranging from 400 to 600 °C using a pulsed d.c. plasma with various pulse duration/repetition ratios in an N2H2 gas mixture. The structure and composition of the plasma-nitrided surface layer were analysed by means of X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), optical microscopy and microhardness testing. The corrosion behaviour of the S phase was also investigated. The maximum Knoop hardness after plasma nitriding is about 1400 HK 0.01 and the maximum thickness of the compound layer is 34 μm. XRD patterns show that the surface layer consists of the S phase only. The corrosion performance was tested in 0.05 M Na2SO4 solution at pH 3.3 and in neutral 3.5% NaCl solution at ambient temperature. Potentiostatic and potentiodynamic experiments yielded slightly higher passive corrosion currents for plasma-nitrided 304L. Pitting corrosion in neutral electrolytes containing chloride ions was observed only for untreated 304L. The passive layers formed on both types of samples were similar in constitution and thickness as determined from XPS sputter profiles.

Mapping of human and macaque sensorimotor areas by integrating architectonic, transmitter receptor, MRI and PET data.

Abstract: The human and macaque sensorimotor cortex was subdivided into numerous areas by a correlative analysis based on cytoarchitectonics, myeloarchitecture and the distribution of transmitter receptors. Receptor densities and laminar distribution patterns differ not only between motor and somatosensory regions, but also between different areas within these regions of the cortex. Changes in receptor distribution often match architectonically defined borders. Receptor findings provide new criteria for a more detailed mapping in the human brain which cannot be achieved by cytoarchitectonic analysis alone. Morphological data on these areas were integrated with functional data from positron emission tomography (PET) on the basis of a recently developed computerised brain atlas. The central sulcus marks the border between (1) the agranular motor cortex with a generally low density of glutamatergic, muscarinic, GABAergic and serotoninergic receptors, and (2) the granular somatosensory cortex with higher densities of these receptors. Rostral to the primary motor cortex, 2 isocortical areas are found on the mesial cortex which probably represent the functionally defined supplementary motor areas (SMA) SMA-proper (caudally) and pre-SMA (rostrally). Below SMA-proper the areas 24d (macaque) and the caudal cingulate motor area cmc (human) are located in the cingulate sulcus. Both regions correspond to the 'posterior cingulate motor areas' of recent PET studies and to the posterior part of the agranular cingulate cortex of architectonic studies. Below pre-SMA the area 24c (macaque) and the rostral cingulate motor area cmr (human) are located in the cingulate sulcus; they correspond to the 'anterior cingulate motor areas' of recent PET observations and to the anterior part of the agranular cingulate cortex of architectonic studies. Homologous sensorimotor areas can be defined in both species on the basis of common architectonic features.

Diagnostic scores for acute appendicitis. Abdominal Pain Study Group.

Abstract: But: Determiner la valeur de scores predictifs pour le diagnostic d'appendicite aigue. Type d'etude: Evaluation multicentrique prospective de donnees informatiques. Provenance: Six departements de chirurgie, Allemagne. Patients: Mille deux cent cinquante quatre patients ayant un syndrome douloureux abdominal. Methodes: Mesure de la performance diagnostique de 10 scores a l'aide d'une base de donnee de criteres standardises et comparer les resultats avec ceux deja publies dans la litterature. Principaux criteres de jugement: La capacite d'un score a repondre a un certain nombre de criteres: taux d'appendicectomie inutile inferieur ou egal a 15%, taux de perforation potentielle inferieur ou egal a 35%, taux de perforation meconnue inferieur ou egal a 15%, et taux de diagnostic d'appendicite meconnu inferieur ou egal a 5%. Resultats: Une relecture des donnees deja publiees a montre que le score d'Alvarado repondait aux quatre criteres et que ceux de Lindberg, de Fenyo et de Christian a deux criteres chacun. En les appliquant a notre base de donnees (douleur abdominale aigue, suspicion d'appendicite), aucun des scores n'a repondu aux criteres, meme en faisant varier systematiquement la valeur seuil. Il y avaient des differences significatives entre les scores. Conclusions: Les donnees publiees precedemment semblent se conformer a nos criteres standardises, mais l'application des scores a notre base de donnees aboutit a un performance mediocre pour chacun d'entre eux. Les donnees publiees semblent biaisees de facon optimiste tandis que notre evaluation donne une estimation de la pratique quotidienne dans differentes situations cliniques plus proche de la realite. D'autres etudes a grande echelle avec des criteres precis sont necessaires pour evaluer l'interet clinique de l'etablissement du diagnostic d'appendicite aigue par des scores

Nitric oxide generation during cellular metabolization of the diabetogenic N-methyl-N-nitroso-urea streptozotozin contributes to islet cell DNA damage.

Abstract: The N-methyl-N-nitroso-urea streptozotocin is an antibiotic with diabetogenic, carcinogenic and antitumor activity thought to act via alkylation of DNA and proteins. Evidence points to a release of bioactive nitric oxide (NO) from streptozotocin as an additional cytotoxic activity of this drug. Here we show by EPR spectroscopy, that NO is not generated during spontaneous decay of streptozotocin but that its metabolization in rat hepatocytes and pancreatic islet cells yields NO. This NO formation is not due to a NO synthase (NOS) activity since NO formation in hepatocytes in the presence of streptozotocin is not blocked by the NOS inhibitor NG-methyl-L-arginine. By iNOS-specific RT-PCR no positive signal for specific mRNA presence was obtained in streptozotocin-treated cells, proving that iNOS activity was not induced during cell isolation procedures and did not account for the NO release. Furthermore, early DNA-strand breaks induced either by SZ or by the NO donor nitroprusside were both significantly reduced in the presence of an intracellular NO scavenger. In contrast, DNA damage found after incubation with the purely alkylating agent methylmethanesulfonate was not inhibited by the NO trap. These results prove that intracellular formation of NO occurs during degradation of SZ within cells. This NO appears to contribute significantly to streptozotocin-induced cytotoxicity.

Large-scale plasticity of the human motor cortex.

Abstract: The adult primate brain is capable of modifying rapidly the size of cortical receptive fields or motor output modules in response to altered synaptic input. We used positron emission tomography (PET) to map the regional cerebral blood flow changes related to voluntary finger movements in patients with tumours occupying the hand area of motor cortex. All patients showed activations solely outside the tumour. Compared with the unaffected side, the activations were shifted by 9-43 mm either along the mediolateral body representation of motor cortex or into premotor or parietal somatosensory cortex. These results provide evidence that slowly developing lesions can induce large-scale reorganization that is not confined to changes within the somatotopic body representation in motor cortex.

The chloroplast genome of a chlorophylla+c-containing alga,Odontella sinensis

Abstract: The chloroplast genome of a marine centric diatom,Odontella sinensis, was cloned and sequenced. The circular genome is 119,704 bp in length (AC=Z67753;). It contains an inverted repeat sequence of 7,725 bp separating two single-copy regions of 38,908 and 65,346 bp, respectively, and 174 genes and open reading frames, of which nine are duplicated within the inverted repeat segments.

Electrochemical and thermal oxidation of TiN coatings studied by XPS

Abstract: X-ray pbotoelectron spectroscopy (XPS) has been used to investigate the electrochemical and thermal oxidation of titanium nitride (TiN) coatings prepared by physical vapour deposition (PVD) at 200°C. Electrochemical oxidation of TiN was carried out at various potentials in phthalate buffer solution (pH 5.0). Evaluation of the XPS Ti 2p and N 1s spectra showed the presence of nitride, oxynitride and oxide species in the layer formed by anodic oxidation. The electrochemical oxidation of TiN to TiO 2 proceeds through the formation of a mixed oxynitride/oxide layer, which transforms into oxide (TiO 2 ) at sufficiently positive potentials (E > 1.1 V vs. SHE). The oxidation of TiN to TiO 2 is accompanied by the formation of molecular nitrogen (N 2 ). The thickness of the oxide layer reaches ∼ 7 nm after oxidation at the highest potential (1.9 V). A complete coverage of the TiN surface by TiO 2 leads to an anodic peak in the polarization curve. On the basis of angle-resolved XPS measurements, two types of oxynitride species are identified, which are distributed differently throughout the oxidized layer. X-ray photoelectron spectroscopy depth profiles of TiN oxidized at 450°C and 600°C in an oxygen flow reveal that at the lower temperature an oxynitride layer is formed, whereas a thick TiO 2 layer appears on top of TiN at the higher temperature. The interface between the nitride and oxide phases is relatively sharp. It is suggested that the mechanism of TiN oxidation proceeds by a progressive replacement of nitrogen by oxygen. The TiN coatings can be used up to 600°C as a protective coating in an oxygen atmosphere. Valance band spectra of TiN, as well as of electrochemically and thermally oxidized TiN, are presented and discussed.