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C Brunner

Publications and source records attributed to C Brunner.

At least 19 recordsLinked to original sources
PubMed2006

Seperability of four-class motor imagery data using independent components analysis.

This paper compares different ICA preprocessing algorithms on cross-validated training data as well as on unseen test data. The EEG data were recorded from 22 electrodes placed over the whole scalp during motor imagery tasks consisting of four different classes, namely the imagination of right hand, left hand, foot and tongue movements. Two sessions on different days were recorded for eight subjects. Three different independent components analysis (ICA) algorithms (Infomax, FastICA and SOBI) were studied and compared to common spatial patterns (CSP), Laplacian derivations and standard bipolar derivations, which are other well-known preprocessing methods. Among the ICA algorithms, the best performance was achieved by Infomax when using all 22 components as well as for the selected 6 components. However, the performance of Laplacian derivations was comparable with Infomax for both cross-validated and unseen data. The overall best four-class classification accuracies (between 33% and 84%) were obtained with CSP. For the cross-validated training data, CSP performed slightly better than Infomax, whereas for unseen test data, CSP yielded significantly better classification results than Infomax in one of the sessions.

Adult↗
PubMed2006

Mu rhythm (de)synchronization and EEG single-trial classification of different motor imagery tasks.

We studied the reactivity of EEG rhythms (mu rhythms) in association with the imagination of right hand, left hand, foot, and tongue movement with 60 EEG electrodes in nine able-bodied subjects. During hand motor imagery, the hand mu rhythm blocked or desynchronized in all subjects, whereas an enhancement of the hand area mu rhythm was observed during foot or tongue motor imagery in the majority of the subjects. The frequency of the most reactive components was 11.7 Hz +/- 0.4 (mean +/- SD). While the desynchronized components were broad banded and centered at 10.9 Hz +/- 0.9, the synchronized components were narrow banded and displayed higher frequencies at 12.0 Hz +/- 1.0. The discrimination between the four motor imagery tasks based on classification of single EEG trials improved when, in addition to event-related desynchronization (ERD), event-related synchronization (ERS) patterns were induced in at least one or two tasks. This implies that such EEG phenomena may be utilized in a multi-class brain-computer interface (BCI) operated simply by motor imagery.

Adult↗
PubMed2006

15 years of BCI research at Graz University of Technology: current projects.

Over the last 15 years, the Graz Brain-Computer Interface (BCI) has been developed and all components such as feature extraction and classification, mode of operation, mental strategy, and type of feedback have been investigated. Recent projects deal with the development of asynchronous BCIs, the presentation of feedback and applications for communication and control.

Animals↗
PubMed2005

Beta rebound after different types of motor imagery in man.

We investigated the behavior of short-lasting beta bursts (beta rebound, beta ERS) induced after imagination of hand, foot or tongue movement. Nine able-bodied subjects were asked to imagine one type of movement following the presentation of a visual cue stimulus. EEG was recorded from 60 closely spaced electrodes placed over frontal, central and parietal areas. Spatiotemporal ERD/ERS patterns were evaluated in form of time-frequency maps. Seven out of nine subjects displayed a significant short-lasting beta power increase (beta rebound) after termination of imagery of movement of both feet in the frequency range of 23-29Hz with a clear maximum at the vertex. In contrast, only two subjects displayed a clear beta rebound at the vertex after imagery of one of the hands, although five exhibited a significant beta rebound at the contralateral side of the head. None showed a beta rebound after tongue motor imagery. The midcentrally located beta rebound is interpreted as an electrophysiological correlate of a simultaneous "resetting" of overlapping neural networks in the foot representation areas and the SMA.

Adult↗
PubMed2005

Bruton's Tyrosine Kinase is involved in innate and adaptive immunity.

Btk is a cytoplasmic tyrosine kinase, which is mainly involved in B cell receptor signalling. Gene targeting experiments revealed that Btk is important for B cell development and function. However, Btk is not only expressed in B cells, but also in most other haematopoietic lineages except for T cells and plasma cells. Recently we found that Btk is involved in Toll-like receptor signalling. Toll-like receptors play an important role in innate immunity. They are highly expressed on mast cells, macrophages and dendritic cells, which are essential for the recognition and consequently for the elimination of microbial pathogens. Therefore Btk might play an important role for the function of immunocompetent cells of innate as well as adaptive immunity.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed2003

[Chromosomal alterations in juvenile angiofibromas].

INTRODUCTION: Despite their benign histological appearance, juvenile angiofibromas, which occur mainly in adolescent males, have a locally aggressive growth pattern. beta-catenin-mutations represent their only known genetic abnormality. MATERIAL AND METHODS: Angiofibroma tissue from seven patients was available for comparative genomic hybridization (CGH). RESULTS: In six out of the seven angiofibromas, CGH detected various abnormalities on 18 different chromosomes. Frequent chromosomal gains were observed on chromosomes 4q, 6q, and 8q. In four out of seven angiofibromas a complete loss of the chromosome Y was detected. CONCLUSIONS: CGH is a suitable method for the examination of angiofibromas for genetic alterations. Considering the sex distribution of this neoplasm, the frequent loss of chromosome Y is of particular interest.

Adolescent↗
PubMed2003

[Malignant transformation of a tubular adenoma in the paranasal sinuses?].

BACKGROUND: Whereas a tubular adenoma is a unique finding within the paranasal sinuses, intestinal adenocarcinomas are especially in patients with long-term exposure to wood dust, common tumours in this location. CASE: In a 65 year old joiner endonasal sinus surgery performed to treat suspected chronic pansinusitis brought up by chance the histological finding of a tubular adenoma. As the patient at first refused surgical revision, but magnetic resonance imaging during follow-up revealed evidence for a space occupying lesion affecting the ethmoid and sphenoid sinuses revision surgery took place one year later. Histopathological evaluation now found a papillary adenocarcinoma. Clinical follow-up and magnetic resonance imaging one year after second surgery found no evidence for tumour recurrence. CONCLUSIONS: Progression of a tubular adenoma to an adenocarcinoma like in the adenoma-carcinoma model well known for colorectal carcinomas has so far not been observed within the paranasal sinuses. But, an adenocarcinoma already present at the time of first surgery can not be ruled out completely in the presented case as histopathological evaluation may have failed to detect an adenocarcinoma in the available specimens after first surgery. Either malignant transformation of a tubular adenoma had occurred or proof of an adenocarcinoma has failed with misdiagnosis of a tubular adenoma. A tubular adenoma as well as an adenocarcinoma require complete resection and careful clinical and radiological follow-up to avoid adenocarcinoma development from a tubular adenoma or to detect an adenocarcinoma by histological evaluation of the whole specimen.

Adenocarcinoma, Papillary↗
PubMed2001

Catecholamines response of high performance wheelchair athletes at rest and during exercise with autonomic dysreflexia.

Autonomic dysreflexia presents a special situation in high-lesion spinal cord injury, however, intentionally or self-induced autonomic dysreflexia directly before or during competition to increase performance, so called 'boosting', is also being reported. In order to examine the influence of autonomic dysreflexia on plasma catecholamines, cardiocirculatory and metabolic parameters, 6 spinal cord injured wheelchair athletes with high-level lesions underwent wheelchair ergometry without (ST1) and with (ST2) autonomic dysreflexia. At the point of exhaustion significantly higher values for norepinephrine and epinephrine were observed in ST2 than in ST1. During autonomic dysreflexia a significantly higher peak performance (77.5 vs. 72.5 watt), higher peak heart rate (161 vs. 149 x min(-1)), and peak oxygen consumption (1.96 vs. 1.85 l x min(-1)), with comparable peak lactate (7.11 vs. 7.00 mmol x l(-1)) were reached on average. The blood pressure values in ST2 were partially hypertensive and higher than in ST1. In conclusion, autonomic dysreflexia, as a sympathetic spinal reflex, leads to a higher release of catecholamines during exercise. This results in higher peak performance, peak heart rate, peak oxygen consumption, and higher blood pressure values. The peak lactate, as an indicator of the anaerobic lactate metabolism, was unchanged. However, autonomic dysreflexia presents an unpredictable risk, caused predominantly by hypertensive blood pressure values, for high-lesion spinal cord injured persons at rest and more so during exercise; it is seen as a prohibited manipulation by the doping guidelines of the International Paralympic Committee.

Adult↗
PubMed2001

Aerosolised iloprost improves pulmonary haemodynamics in patients with primary pulmonary hypertension receiving continuous epoprostenol treatment.

BACKGROUND: Continuous intravenous treatment with epoprostenol significantly improves pulmonary haemodynamics and survival in patients with primary pulmonary hypertension (PPH). Its beneficial effect, however, may be blunted due to adverse effects such as catheter sepsis and systemic hypotension. Recent investigations have shown that inhaled iloprost is effective in the treatment of PPH. Based on their different pharmacokinetics, we hypothesised that the combination of intravenous epoprostenol and inhaled iloprost would be more efficacious than epoprostenol alone during acute testing in patients with PPH. METHODS: The effect of a single dose of inhaled iloprost (30 microg total over 15 minutes) on pulmonary haemodynamics was examined in eight patients with PPH (initial non-responders to nitric oxide) who had considerable adverse effects during treatment with epoprostenol. RESULTS: The combination of inhaled iloprost and intravenous epoprostenol significantly improved mean pulmonary artery pressure (MPAP), cardiac index (CI), mixed venous oxygen saturation (SvO2), and systemic arterial oxygen pressure (PaO2) compared with epoprostenol treatment alone. Mean systemic arterial pressure (MSAP) and pulmonary capillary wedge pressure (PCWP) remained unchanged. CONCLUSIONS: The pulmonary vasoreactivity shown by additional iloprost inhalation during effective epoprostenol treatment suggests that an improvement of treatment for pulmonary hypertension may be possible by combining vasoactive substances.

Administration, Inhalation↗
PubMed2001

Preferential suppression of CXCR4-specific strains of HIV-1 by antiviral therapy.

To initiate infection, HIV-1 requires a primary receptor, CD4, and a secondary receptor, principally the chemokine receptor CCR5 or CXCR4. Coreceptor usage plays a critical role in HIV-1 disease progression. HIV-1 transmitted in vivo generally uses CCR5 (R5), but later CXCR4 (X4) strains may emerge; this shift heralds CD4+ cell depletion and clinical deterioration. We asked whether antiretroviral therapy can shift HIV-1 populations back to R5 viruses after X4 strains have emerged, in part because treatment has been successful in slowing disease progression without uniformly suppressing plasma viremia. We analyzed the coreceptor usage of serial primary isolates from 15 women with advanced disease who demonstrated X4 viruses. Coreceptor usage was determined by using a HOS-CD4+ cell system, biological and molecular cloning, and sequencing the envelope gene V3 region. By constructing a mathematical model to measure the proportion of virus in a specimen using each coreceptor, we demonstrated that the predominant viral population shifted from X4 at baseline to R5 strains after treatment. Multivariate analyses showed that the shift was independent of changes in plasma HIV-1 RNA level and CD4+ cell count. Hence, combination therapy may lead to a change in phenotypic character as well as in the quantity of HIV-1. Shifts in coreceptor usage may thereby contribute to the clinical efficacy of anti-HIV drugs.

Anti-HIV Agents↗
PubMed2000

Enhanced dendritic cell maturation by TNF-alpha or cytidine-phosphate-guanosine DNA drives T cell activation in vitro and therapeutic anti-tumor immune responses in vivo.

Dendritic cells (DC) manipulated ex vivo can induce tumor immunity in experimental murine tumor models. To improve DC-based tumor vaccination, we studied whether DC maturation affects the T cell-activating potential in vitro and the induction of tumor immunity in vivo. Maturation of murine bone marrow-derived DC was induced by GM-CSF plus IL-4 alone or by further addition of TNF-alpha or a cytidine-phosphate-guanosine (CpG)-containing oligonucleotide (ODN-1826), which mimics the immunostimulatory effect of bacterial DNA. Flow cytometric analysis of costimulatory molecules and MHC class II showed that DC maturation was stimulated most by ODN-1826, whereas TNF-alpha had an intermediate effect. The extent of maturation correlated with the secretion of IL-12 and the induction of alloreactive T cell proliferation. In BALB/c mice, s.c. injection of colon carcinoma cells resulted in rapidly growing tumors. In this model, CpG-ODN-stimulated DC cocultured with irradiated tumor cells also induced prophylactic protection most effectively and were therapeutically effective when administered 3 days after tumor challenge. Thus, CpG-ODN-enhanced DC maturation may represent an efficient means to improve clinical tumor vaccination.

Adjuvants, Immunologic↗
PubMed2000

Comparative genomic hybridization reveals recurrent enhancements on chromosome 20 and in one case combined amplification sites on 15q24q26 and 20p11p12 in glioblastomas.

We examined homogenized tissue samples of biopsies from 19 astrocytomas of different grades for genetic imbalances using comparative genomic hybridization (CGH): three astrocytomas grade II, and 16 astrocytomas grade IV (glioblastoma multiforme), one of the glioblastomas representing the recurrence of a benign oligoastrocytoma. In two of three cases of astrocytoma grade II, a gain of chromosome 7 was found. The alterations in the glioblastomas were complex, and most frequently showed the characteristic gain of chromosome 7 and loss of chromosome 10. The single analyzed case of recurrence of an oligoastrocytoma was characterized by a unique CGH pattern. This tumor showed two distinct alterations: apart from an amplification on 15q24q26, we found a distinct amplification of a small region on 20p11.2p12, which has not been previously described in brain tumors. Partial or complete gains of chromosome 20 arose in six other tumors; we conclude that chromosome 20 in particular 20p11. 2p12, may harbor relevant genes for glioma progression.

Adult↗
PubMed2000

Accuracy of echocardiographic right ventricular parameters in patients with different end-stage lung diseases prior to lung transplantation.

BACKGROUND: Because there are few data available on the accuracy of 2D-echocardiography to assess right ventricular (RV) size and function in patients with far-advanced lung disease, in this prospective study, we compared various echocardiographic RV parameters with RV volumes derived from magnetic resonance imaging (MRI). METHODS: In 32 patients (18 male, 17 female) presenting for lung transplantation, we measured RV end-diastolic and end-systolic area as well as derived RV fractional area change, long-axis diameter, short-axis diameter, tricuspid valve anulus diameter (using 2D apical or sub-costal 4-chamber view), and RV end-diastolic diameter (using M-mode in the parasternal short-axis view). These values were compared with RV end-diastolic and end-systolic volumes derived by MRI, serving as the gold standard. RESULTS: Right ventricular end-diastolic area was the most accurate echocardiographic parameter of RV size (correlation to MRI: r = 0.88, p < 0.001), followed by RV end-diastolic short-axis diameter (r = 0.75, p < 0.001), long axis diameter (r = 0.66, p < 0.001), and tricuspid valve anulus diameter (r = 0.63, p < 0.001). In contrast, M-mode measurement of RV end-diastolic diameter was possible in only 24/35 (68%) patients and showed a weak correlation to MRI-derived RV end-diastolic volume (r = 0.56, p = 0.004). Right ventricular fractional area change correlated well with MRI-derived RV ejection fraction (r = 0.84, p < 0.0001). In a sub-group analysis, patients with vascular lung disease showed best agreement between both methods for RV end-diastolic area and RV fractional area change compared with patients with restrictive or obstructive lung disease. CONCLUSION: This study shows that in patients with far-advanced lung diseases, RV end-diastolic area demonstrated the best correlation with MRI-derived measurement of RV end-diastolic volume, and RV fractional area change compared favorably with MRI-derived ejection fraction. Despite reduced image quality, especially in patients with obstructive lung disease, these parameters can yield clinically valuable information.

Adult↗
PubMed2000

Repertoire dynamics of autoreactive T cells in multiple sclerosis patients and healthy subjects: epitope spreading versus clonal persistence.

Autoantigen-specific T-lymphocytes are present in patients with autoimmune disease and in normal subjects. Little is currently known about the temporal variation (dynamics) of the immune repertoire of these autoreactive T cells. We analysed the long-term variation of the immune repertoire of T cells specific for myelin basic protein (MBP) in five untreated patients with multiple sclerosis and four normal control subjects over a mean observation period of 6 years. MBP-specific CD4(+) T-cell lines were selected with purified human MBP, and their epitope specificity was mapped with overlapping synthetic peptides. Three distinct patterns of repertoire development were observed. (i) Two patients and three control subjects maintained a broad epitope response with fluctuations over time. (ii) Two patients initially showed a focused response that broadened over the course of 6 years; this finding could be described as intramolecular epitope spreading. (iii) In one patient and one control subject, a strikingly focused response, which was directed to a cluster of nested epitopes in the MBP region 83-102, persisted over time. T-cell receptor Vbeta sequence analysis allowed us to trace individual clones of MBP-specific T cells for up to 7 years in the peripheral circulation in four of the five patients and three of the four controls, suggesting that the long-term persistence of MBP-specific T-cell clones is a common feature of the T-cell repertoire not unique to multiple sclerosis. The persisting MBP-specific T-cell clones were not detectable in the blood of one of the patients by complementarity-determining region (CDR)-3 spectratyping, indicating that their frequency does not exceed 1 in 5000 T cells. The temporal characteristics of the MBP-specific T-cell repertoire described here are relevant to therapeutic strategies targeting autoantigen-specific T cells in multiple sclerosis and other autoimmune diseases.

Adult↗
PubMed2000

Arterial properties of the carotid and femoral artery in endurance-trained and paraplegic subjects.

In humans, the relationships of blood flow changes to structure, function, and shear rate of conducting arteries have not been thoroughly examined. Therefore, the purpose of this study was to investigate these parameters of the elastic-type, common carotid artery (CCA) and the muscular-type, common femoral artery (CFA) in long-term highly active and extremely inactive individuals, assuming that the impact of activity-induced blood flow changes on conduit arteries, if any, should be seen in these subjects. We examined 21 highly endurance-trained athletes (A), 10 paraplegic subjects (P), and 20 sedentary subjects (S) by means of noninvasive ultrasound. As a result, the CFA diameter and compliance were highest in A (9.7+/-0.81 mm; 1.84 +/-0.54 mm(2)/kPa) and lowest in P (5.9+/-0.7 mm; 0.54+/-0.27 mm(2)/kPa) compared with S (8.3+/-1.0 mm; 0.92+/-0.48 mm(2)/kPa) with P <0.01 among the groups. Both parameters correlated with each other (r = 0.62; P<0.01). Compared with A (378+/-84 s(-1); 37+/-15 s(-1)) and S (356+/-113 s(-1); 36+/-20 s(-1)), the peak and mean shear rates of the CFA were almost or more than doubled in P (588+/-120 s(-1); 89+/-26 s(-1)). In the CCA, only the compliance and peak shear rate showed significant differences among the groups (A: 1.28+/-0.47 mm(2)/kPa, 660+/-138 s(-1); S: 1.04+/-0.27 mm(2)/kPa, 588+/-109 s(-1); P: 0.65+/- 0.22 mm(2)/kPa, 490+/-149 s(-1); P<0.05). In conclusion, the results suggest a structural and functional adaptation in the CFA and a predominantly functional adaptation of the arterial wall properties to differences in the physical activity level and associated exercise-induced blood flow changes in the CCA. The results for humans confirm those from animal experiments. Similar shear rate values of S and P in the CFA support the hypothesis of constant shear stress regulation due to local blood flow changes in humans. On the other hand, the increased shear rate in the CFA in P indicates an at least partially nonphysiological response of the arterial wall in long-term chronic sympathectomy due to a change in local blood flow.

Adult↗
PubMed1999

Effect of plasminogen activators on human recombinant apolipoprotein(a) having the plasminogen activation cleavage site.

The serine-proteinase domain in human apolipoprotein(a) [apo(a)] and plasminogen exhibit 89% sequence identity including the catalytic triad. Cleavage of the Arg(561)-Val(562) activation site in plasminogen by either tissue- or urokinase-type plasminogen activator results in formation of the fibrinolytic enzyme plasmin. Apo(a) does not contain measurable amidolytic activity nor can it be activated by plasminogen activators. It has been suggested that the latter finding might be explained by the substitution of the plasminogen Arg-Val activation site by Ser-Ile in apo(a). To investigate if introduction of the Arg-Val activation site in apo(a) might result in sensitivity towards plasminogen activators, we expressed wild-type and Arg-Val mutant recombinant apo(a) [r-apo(a)] in human embryonic kidney and hepatocyte cell lines. Free r-apo(a) and lipoprotein-like particles [r-Lp(a)] were obtained in the culture supernatants of transfected 293 and HepG2 cells, respectively. Incubation of mutant r-apo(a)/r-Lp(a) with plasminogen activators produced neither plasmin-like activity nor cleavage at the Arg-Val activation site, even in the presence of various stimulators of plasminogen activation. Our data suggest that the high selectivity of activators for plasminogen activation requires interactions with regions in plasminogen distant from the activation disulfide loop which are not present in apo(a).

Amino Acid Sequence↗
PubMed1999

Pyrofluid inhalation in "fire-eaters": sequential findings on CT.

We report the sequential computed tomography (CT) findings in two fire-eaters after accidental inhalation of pyrofluid. The initial chest radiographic findings were ambiguous and the interpretation of the radiographs was biased by clinical history unrelated to fire eating. On CT, pneumatoceles were the major findings in both patients. The pneumatoceles resolved rapidly, leaving only minimal scarring. Our cases illustrate the sequential evolution of pneumatoceles in fire-eaters after the inhalation of pyrofluid and documents the rapidity with which the lesions regress. The rare accidental inhalation of pyrofluid in fire-eaters may produce a puzzling clinical and radiographic picture and can be confused with other lung disorders.

Adult↗