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G Bauer

Publications and source records attributed to G Bauer.

At least 91 records · Page 5Linked to original sources
PubMed2001

Recent advances in the diagnosis and treatment of epilepsy.

Recent advances in the diagnosis and treatment of epilepsies are discussed with special consideration of epidemiology and classification, progress in neuroimaging, electrophysiological studies using EEG and MEG, initiation of medical and surgical treatment, the role of new antiepileptic drugs and selected aspects of genetics of idiopathic epilepsies. In addition from conclusions obtained by the review of recent developments suggestions for future work in Europe are discussed. A constructive approach from multicenter studies requires homologous definitions, documentations and standardization of procedures of trials for European multicenter studies.

Anticonvulsants↗
PubMed2001

Deep wound infection after vagus nerve stimulator implantation: treatment without removal of the device.

Effective treatment of deep wound infection without removal of a previously implanted foreign body is difficult. The Neurocybernetic Prosthesis (NCP) System (Cyberonics Inc., Webster, TX, U.S.A.), implanted for vagus nerve stimulation in patients with medically refractory epilepsy, uses coil-like electrodes placed around the left vagus nerve after exposure of the nerve in the carotid sheath. Infection within this compartment endangers the contained structures and makes removal of the system hazardous. We report the case of one patient implanted with the NCP who underwent successful open wound treatment without removal of the system. A 35-year-old man had local signs of wound infection 5 weeks after implantation of a vagus nerve stimulator. Systemic signs of infection were absent. C-reactive protein was slightly elevated, but all other laboratory values were normal. After open wound debridement and thorough rinsing with bacitracin-containing solution, the wound was packed with 3% iodoformized gauze. The NCP was left in place. Systemic antibiotic therapy with fosfomycin and cefmenoxim was started. Cultures confirmed an infection with Staphylococcus aureus. The wound was rinsed daily with 3% hydrogen peroxide solution and 5% saline until cultures were sterile and granulation tissue started to fill the wound. Delayed primary closure was performed 2 weeks later. Wound healing was accomplished without removal of the device. No signs of recurrent infection were observed during a follow-up of 1 year. Open wound treatment without removal of the implanted vagus nerve stimulator is feasible in cases of deep cervical wound infection and can be an alternative if removal of the device appears hazardous.

Adult↗
PubMed2001

Lactobacilli-mediated control of vaginal cancer through specific reactive oxygen species interaction.

Klebanoff et al. proposed that hydrogen peroxide-producing lactobacilli and peroxidase in the vagina of healthy women might be responsible for the prevention of vaginosis and also might exert an antitumor effect (1). Based on recent evidence on superoxide anion generation by transformed cells (2,3) and on the potential of myeloperoxidase for selective apoptosis induction in transformed cells (4), a model for specific reactive oxygen species interaction during lactobacilli-mediated tumor control in the vagina is presented here. We propose that peroxidase, which converts hydrogen peroxide into hypochlorous acid, is responsible for creating a microbicidal vaginal milieu by maintaining a balanced, non-toxic, steady state level of the microbicides H(2)O(2)and HOCI. In case individual superoxide anion-producing transformed cells eventually appear in the mucosa they will be driven into apoptosis by interaction of HOCI with superoxide anions which leads to the generation of hydroxyl radicals. Hence selective apoptosis induction in transformed cells represents the key element of lactobacilli-mediated antitumor defense. Since papilloma virus infected cells are resistant to this pathway of apoptosis induction, they are plausible candidates for circumvention of lactobacilli-mediated control of oncogenesis.

Apoptosis↗
PubMed2001

An alternative signaling pathway based on nitryl chloride during intercellular induction of apoptosis.

Transforming growth factor (TGF)-beta pretreated nontransformed fibroblasts induce apoptosis selectively in transformed fibroblasts. This potential control step during oncogenesis has been termed intercellular induction of apoptosis. Selectivity and efficiency of intercellular induction of apoptosis depend on transformed target cell-derived superoxide anions that drive two intercellular signaling pathways--the HOCl/hydroxyl radical and the nitric oxide (NO)/peroxynitrite pathway. Other natural antitumor systems like macrophages or cells of the granulocyte lineage seem to utilize the same signaling chemistry. Our data demonstrate the existence of an alternative signaling pathway in these systems. This pathway depends on the presence of nitrite and is still effective when the two conventional signaling pathways are blocked by superoxide dismutase (SOD). Nitrite-dependent apoptosis induction is neither blocked by SOD nor by the hydroxyl radical scavenger terephthalate, but it is inhibited by the peroxidase inhibitor aminobenzoyl hydrazide and by the hypochlorous acid (HOCl) scavenger taurine. Therefore, nitrite, that is nontoxic for our cells, seems to interact with HOCl to form the apoptosis inducer nitryl chloride. Nitryl chloride-mediated apoptosis induction might be relevant for apoptosis induction in tumor cells that release SOD and thus escape the two classical signaling pathways.

Animals↗
PubMed2001

ras oncogene expression determines sensitivity for intercellular induction of apoptosis.

Fibroblasts carrying an inducible ras oncogene acquire the transformed phenotype after oncogene induction. As a consequence, the transformed cells become sensitive to intercellular induction of apoptosis, a novel regulatory process directed by non-transformed fibroblasts against their transformed descendants. The causal relationship between oncogene expression and sensitivity to intercellular induction of apoptosis is based on extracellular superoxide anion production by oncogene-expressing cells. Superoxide anions (after dismutation to hydrogen peroxide) thereby foster HOCl synthesis and at the same time direct the selectivity of apoptosis induction through hydroxyl generation from HOCl. In parallel, ras expression enhances the sensitivity of fibroblasts for apoptosis-inducing stimuli like cycloheximide, ceramide and mitomycin C. This sensitization seems to be based on a decreased concentration of short lived endogenous apoptosis inhibitors. TGF-beta, like ras induction, decreases the concentration of endogenous apoptosis inhibitors, but does not induce the transformed phenotype. Therefore, TGF-beta treatment alone is not sufficient to render fibroblasts sensitive for intercellular induction of apoptosis, but TGF-beta treatment in parallel with ras activation enhances intercellular induction of apoptosis. Our findings demonstrate that Ras-mediated superoxide anion production determines sensitivity to intercellular induction of apoptosis, whereas the parallel decrease in endogenous apoptosis inhibitors modulates the kinetics of apoptosis induction.

Animals↗
PubMed2001

Nanofilms and nanoclusters: energy sources driving fluorophores of biochip bound labels.

Nanoclusters and nanofilms have the potential to amplify fluorescence and thus to enhance the signal of labeled biomolecules on biochip surfaces. Fluorescent molecules are bound at a certain distance to a resonant layer of a metal or a semiconductor or both, resulting in enhanced absorption and emission of the fluorophore within the electromagnetic near-field. This property makes the system highly useful for interaction studies, including those of DNA and proteins. Due to the amount of data, derived from various sequencing projects and from Proteomic interaction studies within the next years, microarrays (or biochips) will represent a central technology in every lab facilitating high-throughput screening and being easily interfaced with computer databases. However, most chips suffer from the disadvantage of insufficient signal-to-noise (background) ratio and are thus limited to molecules of medium-to-high abundance. Novel approaches are needed for identification of, e.g., low copy RNAs or regulatory proteins. Here we present a study, using novel surface enhanced chips in the standard glass-slide-formats. Applying surface-enhanced fluorescence (SEF), the chips turned out to be useful for interaction studies, such as DNA hybridization, thereby strongly enhancing the on-chip-signals. Compared to standard glass-slide-DNA chips, both the fluorescent signals as well as signal-to-noise ratio were considerably higher.

Animals↗
PubMed2001

Central and ambivalent role of hydrogen peroxide during intercellular induction of apoptosis.

TGF-beta pretreated non-transformed fibroblasts induce apoptosis selectively in transformed fibroblasts. This novel potential control step of oncogenesis has been termed intercellular induction of apoptosis. Intercellular signalling depends on target cell-derived extracellular superoxide anions that drive the efficiency of two signalling pathways. These are based on the formation of peroxynitrite through nitric oxide/superoxide anion interaction and on the generation of hypochlorous acid, followed by interaction of hypochlorous acid with superoxide anions, leading to the generation of hydroxyl radicals. This report demonstrates that exogenous hydrogen peroxide causes an overall inhibition of intercellular induction of apoptosis through blunting of the nitric oxide/peroxynitrite signalling pathway. When the HOCl/hydroxyl radical signalling pathway is studied separately (in the presence of an inhibitor of nitric oxide synthesis), exogenous hydrogen peroxide causes an enhancement of apoptosis induction. Based on the dual and adverse effects of hydrogen peroxide on intercellular induction of apoptosis, its steady state concentration seems to be one of the critical parameters that determine efficiency of apoptosis induction in transformed cells.

Apoptosis↗
PubMed2001

Selective apoptosis induction in transformed fibroblasts by B cell lines: involvement of reactive oxygen and nitrogen species.

B cell lines induce apoptosis selectively in transformed fibroblasts. Apoptosis induction is independent of direct cell contact. It seems to be based on superoxide anion production by transformed cells, subsequent spontaneous dismutation to hydrogen peroxide and utilization of the hydrogen peroxide by a peroxidase released by effector cells. The peroxidase then generates hypochlorous acid which may interact with target cell derived superoxide anions, yielding apoptosis-inducing hydroxyl radicals. In parallel, NO released by effector cells may interact with target cell derived superoxide anions and generate the apoptosis inducer peroxynitrite. Therefore, in parallel to their specific functions in humoral immunity, B cells seem to have the potential to contribute to those signalling pathways directed against transformed cells that have been recently shown to be established by TGF-beta treated fibroblasts. This intercellular signalling system seems to represent an evolutionary ancient system for the control of cells that potentially endanger the survival of multicellular organisms.

Acetylcysteine↗
PubMed2001

Chronic epilepsy with complex partial seizures is not always medically intractable--a long-term observational study.

OBJECTIVE: To study the prognosis of patients with complex partial seizures (CPS) with or without simple partial (SPS) and secondarily generalized tonic-clonic seizures (GTCS) and to analyze the factors related to the degree of medical responsiveness. MATERIAL AND METHODS: A total of 266 adult patients with CPS were included in a hospital based observational survey with a follow-up of 2 to 25 years. Clinical characteristics, seizure frequency, electroencephalography (EEG), cerebral computed tomography (CCT) and magnetic resonance imaging (MRI) findings were analyzed. Patients were categorized according to their degree of medical responsiveness into one of three groups: seizure free, improved control (>50% seizure reduction) and poor control. RESULTS: Mean age at follow-up was 44.7 years (SD 14.7, range 19-93). Mean age at seizure onset was 18.1 years (SD 14.7, median 15, range 1-79). Complete seizure control was achieved in 40%, improved seizure control in 36% and poor seizure control in 24%. Patients entered remission after a mean period of 15.7 years (SD 12.6, median 13, range 1-54) of active epilepsy. A third of all seizure-free patients were still in remission 6.1 years (SD 5.3, median 3.5, range 1-18) after discontinuation of antiepileptic drugs (AED). Patients with poor seizure control had a significantly younger age at onset (P<0.01), a higher initial seizure frequency (more than 3 per month) (P<0.01), abnormal neurological examination (P<0.01), and were more often mentally handicapped (P<0.01). Multiple logistic regression analysis revealed a high initial seizure frequency, mental handicap and an abnormal neurological examination as independent risk factors for poor seizure control. A positive family history, a history of febrile convulsions and/or psychosis, an abnormal EEG or MRI was not predictive of poor outcome. CONCLUSIONS: Not all patients with CPS were medically intractable. Seizure remission can be achieved after a long time of active epilepsy. Poor seizure control was associated with a high initial seizure frequency, mental handicap and abnormal neurological examination.

Adult↗
PubMed2001

Simplicity through complexity: immunoblot with recombinant antigens as the new gold standard in Epstein-Barr virus serology.

Immunofluorescence tests have been the gold standard in Epstein-Barr virus (EBV) serology during the past decades. Despite their high quality they cannot resolve significant problems with i) anticellular reactivity of some sera, ii) missing anti-EBNA-1 response in 5% of healthy individuals, and iii) loss of anti-EBNA-1 during immunosuppression. Immunoblots with recombinant EBV antigens (either in the Blot or the Line assay version) allow unequivocal serological diagnosis also in those cases that are problematic for immunofluorescence testing, 1) since due to the use of purified recombinant antigens, anticellular reactivities are no problem, and 2) since a combination of two late markers is tested (p72 and p18). Positive p18-IgG thereby defines those cases of past infections in which p72-IgG (anti-EBNA-1) is missing or has been lost. In nearly all cases, a single IgG test is sufficient for a definitive serological diagnosis. Whenever required, the immunoblot technique allows precise quantitation and avidity determination. The immunoblot with recombinant antigens represents the most sensitive, unequivocal and simple test system available at present, with the highest complexity of information obtained. Therefore, the immunoblot with recombinant antigens should be regarded as the new gold standard in EBV serology.

Antibodies, Viral↗
PubMed2000

Target cell-derived superoxide anions cause efficiency and selectivity of intercellular induction of apoptosis.

Transformed fibroblasts are specifically eliminated by their nontransformed neighbors through intercellular induction of apoptosis. This process depends on the number of nontransformed effector cells and on the local density of transformed target cells. Intercellular signalling is inhibited by SOD (a scavenger of superoxide anions), taurine (a scavenger of HOCl), 4-aminobenzoyl hydrazide (a mechanism-based inhibitor of peroxidase), DMSO (a hydroxyl radical scavenger), and two inhibitors of NO synthase. Therefore, selective apoptosis induction seems to be based on superoxide anion production by transformed cells, their spontaneous dismutation to hydrogen peroxide, and HOCl generation by a novel effector cell-derived peroxidase. HOCl then interacts with target cell-derived superoxide anions to yield hydroxyl radicals. Due to the short diffusion pathway of superoxide anions, hydroxyl radical generation is confined to the intimate vicinity of transformed cells. In parallel, NO derived from effector cells interacts with superoxide anions of target cells to yield the apoptosis inducer peroxynitrite. Reconstitution experiments using transformed or nontransformed cells in conjunction with myeloperoxidase, HOCl, or an NO donor demonstrated that superoxide anions generated extracellularly by transformed cells participate in intercellular signalling and at the same time determine transformed cells as selective targets for intercellular induction of apoptosis.

Animals↗
PubMed2000

Measurement of J/psi and psi(2S) polarization in pp collisions at sqrt[s] = 1.8 TeV.

We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]<P(T)<20 GeV/c and |y|<0.6. For P(T) greater than or approximately equal 12 GeV/c we do not observe significant polarization in the prompt component.

Journal Article↗
PubMed2000

Nanometer-scale resolution of strain and interdiffusion in self-assembled InAs/GaAs quantum dots

Tomographic nanometer-scale images of self-assembled InAs/GaAs quantum dots have been obtained from surface-sensitive x-ray diffraction. Based on the three-dimensional intensity mapping of selected regions in reciprocal space, the method yields the shape of the dots along with the lattice parameter distribution and the vertical interdiffusion profile on a subnanometer scale. The material composition is found to vary continuously from GaAs at the base of the dot to InAs at the top.

Journal Article↗
PubMed2000

Ictal urinary urge indicates seizure onset in the nondominant temporal lobe.

The authors describe six patients with medically refractory temporal lobe epilepsy whose seizures were characterized by an aura of ictal urinary urge. All seizures originated in the nondominant temporal lobe as evidenced from interictal spikes, ictal EEG, and MRI. Ictal SPECT, which was obtained in two patients, showed a hyperperfusion of the insular cortex, indicating a critical role of the insula for the generation of this symptom. Ictal urinary urge represents a new lateralizing sign indicating a seizure onset in the nondominant temporal lobe.

Adolescent↗
PubMed2000

Search for scalar top and scalar bottom quarks in pp collisions at square root s=1.8 TeV.

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp collisions at sqrt[s]=1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.

Journal Article↗
PubMed2000

Search for a W' boson via the decay mode W'-->munumu in 1.8 TeV pp collisions.

We report the results of a search for a W' boson produced in pp collisions at a center-of-mass energy of 1.8 TeV using a 107 pb-1 data sample recorded by the Collider Detector at Fermilab. We consider the decay channel W'-->&munumu and search for anomalous production of high transverse mass munumu lepton pairs. We observe no excess of events above background and set limits on the rate of W' boson production and decay relative to standard model W boson production and decay using a fit of the transverse mass distribution observed. If we assume standard model strength couplings of the W' boson to quark and lepton pairs, we exclude a W' boson with invariant mass less than 660 GeV/c2 at 95% confidence level.

Journal Article↗
PubMed2000

Tuning of vertical and lateral correlations in self-organized PbSe/Pb1-xEuxTe quantum dot superlattices

The tuning of lateral and vertical correlations in self-organized PbSe/Pb 1-xEu xTe quantum dot superlattices by changes in the spacer thicknesses is demonstrated and shown to be due to finite size effects in the dot-dot interactions. As a consequence, different dot arrangements such as vertically aligned dot columns or fcc stacking are obtained for a single material system without changes in growth conditions. The different dot superstructures are shown to exhibit a different scaling behavior of the lateral versus vertical dot separation, as well as a different evolution of dot sizes and shapes.

Journal Article↗