Improving zero-training brain-computer interfaces by mixing model estimators.

OBJECTIVE: Brain-computer interfaces (BCI) based on event-related potentials (ERP) incorporate a decoder to classify recorded brain signals and subsequently select a control signal that drives a computer application. Standard supervised BCI decoders require a tedious calibration procedure prior to every session. Several unsupervised classification methods have been proposed that tune the decoder during actual use and as such omit this calibration. Each of these methods has its own strengths and weaknesses. Our aim is to improve overall accuracy of ERP-based BCIs without calibration. APPROACH: We consider two approaches for unsupervised classification of ERP signals. Learning from label proportions (LLP) was recently shown to be guaranteed to converge to a supervised decoder when enough data is available. In contrast, the formerly proposed expectation maximization (EM) based decoding for ERP-BCI does not have this guarantee. However, while this decoder has high variance due to random initialization of its parameters, it obtains a higher accuracy faster than LLP when the initialization is good. We introduce a method to optimally combine these two unsupervised decoding methods, letting one method's strengths compensate for the weaknesses of the other and vice versa. The new method is compared to the aforementioned methods in a resimulation of an experiment with a visual speller. MAIN RESULTS: Analysis of the experimental results shows that the new method exceeds the performance of the previous unsupervised classification approaches in terms of ERP classification accuracy and symbol selection accuracy during the spelling experiment. Furthermore, the method shows less dependency on random initialization of model parameters and is consequently more reliable. SIGNIFICANCE: Improving the accuracy and subsequent reliability of calibrationless BCIs makes these systems more appealing for frequent use.

[Non-cirrhotic portal hypertension presented by acute upper gastrointestinal bleeding 7 years after oxaliplatin-chemotherapy]. / Nicht zirrhotische portale Hypertension mit bedrohlicher Blutungskomplikation 7 Jahre nach Oxaliplatin-Chemotherapie.

After having received adjuvant FOLFOX treatment consisting of oxaliplatin, folinic acid and fluoruracil following hemicolectomy in colon cancer 7 years ago, the findings of non-cirrhotic portal hypertension presented by acute upper gastrointestinal bleeding in a 49-year old woman were interpreted as oxaliplatin-associated. Imaging techniques, hepatic venous pressure measurement and liver biopsy supported pre-sinusoidal damage due to NRH (nodular regenerative hyperplasia) as the underlying cause, even though histological findings were moderate. Following primary endoscopic treatment, a stable condition has thus far been achievable with standard drug therapy.

Activity increase in respiratory chain complexes by rubella virus with marginal induction of oxidative stress.

Mitochondria are important for the viral life cycle, mainly by providing the energy required for viral replication and assembly. A highly complex interaction with mitochondria is exerted by rubella virus (RV), which includes an increase in the mitochondrial membrane potential as a general marker for mitochondrial activity. We aimed in this study to provide a more comprehensive picture of the activity of mitochondrial respiratory chain complexes I to IV. Their activities were compared among three different cell lines. A strong and significant increase in the activity of mitochondrial respiratory enzyme succinate:ubiquinone oxidoreductase (complex II) and a moderate increase of ubiquinol:cytochrome c oxidoreductase (complex III) were detected in all cell lines. In contrast, the activity of mitochondrial respiratory enzyme cytochrome c oxidase (complex IV) was significantly decreased. The effects on mitochondrial functions appear to be RV specific, as they were absent in control infections with measles virus. Additionally, these alterations of the respiratory chain activity were not associated with an elevated transcription of oxidative stress proteins, and reactive oxygen species (ROS) were induced only marginally. Moreover, protein and/or mRNA levels of markers for mitochondrial biogenesis and structure were elevated, such as nuclear respiratory factors (NRFs) and mitofusin 2 (Mfn2). Together, these results establish a novel view on the regulation of mitochondrial functions by viruses.

Genetic testing and private insurance--a case of "selling one's body"?

Arguments against the possible use of genetic test results in private health and life insurance predominantly refer to the problem of certain gene carriers failing to obtain affordable insurance cover. However, some moral intuitions speaking against this practice seem to be more fundamental than mere concerns about adverse distributional effects. In their perspective, the central ethical problem is not that some people might fail to get insurance cover because of their 'bad genes', but rather that some people would manage to get insurance cover because of their 'good genes'. This paper tries to highlight the ethical background of these intuitions. Their guiding idea appears to be that, by pointing to his favourable test results, a customer might make an attempt to 'sell his body'. The rationale of this concept is developed and its applicability to the case at issue is critically investigated. The aim is to clarify an essential objection against the use of genetic information in private insurance which has not yet been openly addressed in the academic debate of the topic.

A virological survey in migrating waders and other waterfowl in one of the most important resting sites of Germany.

Wild birds are considered a potential reservoir or a carrier of viral diseases and may therefore play a role in the epidemiology of economically important or zoonotic diseases. In 2001 and 2002, a survey with special emphasis on virus isolation in migrating waders and some other birds were conducted. In one of the most important inland resting sites for migratory waterfowl, tracheal and cloacal swabs were collected from 465 waders representing 19 different species, and 165 other birds that were not captured on purpose. A total of 42 avian viruses were isolated, 34 of these were identified as paramyxoviruses (PMVs). The majority of isolates came from waders and wild ducks, and were characterized as PMV-1. In contrast, PMV-4 was found in wild ducks only, PMV-6 was mainly detected in wader species. Four avian influenza viruses (AIVs), belonging to H4 and H3 haemagglutinin subtype, were isolated from wild duck species. Furthermore, four reo-like viruses were isolated from one particular wader species for the first time. The majority of virus positive birds were <1 year old and did not show any clinical symptoms. There was no evidence for the presence of West Nile virus in these birds. These results confirm that the restricted resting sites in Western Europe must be considered as important locations for the intra- and interspecies transmission of avian viruses.

Electron-vibron coupling in high-resolution X-Ray absorption spectra of organic materials: NTCDA on Ag(111).

We report additional rich fine structures in high-resolution near-edge x-ray-absorption fine structure (NEXAFS) spectra of large organic molecules using NTCDA on Ag(111) as an example. These fine structures are completely interpreted as vibronic coupling to electronic core excitations. The coupling is mode selective; predominantly one vibronic mode couples to each excitation. The fit results suggest the occurrence of a Davydov splitting, first observed for core excitons. Morphological differences substantially influence the electron-vibron coupling, indicating a strong intermolecular interaction. Thus NEXAFS becomes a more subtle probe for organic solids.

Multicenter retrospective evaluation of capsule endoscopy in clinical routine.

BACKGROUND AND STUDY AIMS: The small bowel is anatomically difficult to examine; disease conditions are rarely located in it, but can be serious. Neither conventional radiography nor push enteroscopy has sufficient sensitivity and specificity to detect distinct lesions. Wireless capsule endoscopy can theoretically allow imaging of the entire small bowel, with only minimal discomfort for the patient. PATIENTS AND METHODS: Between November 2001 and May 2003, 191 patients received 195 capsules. Data were collected retrospectively from consecutive patients in three centers. The indications for capsule endoscopy were obscure or occult bleeding, suspected Crohn's disease, or other reasons in 151, 25, and 15 patients, respectively. The clinical outcome after 6 months was evaluated on the basis of interviews with patients or relatives. RESULTS: Visualization of the entire small bowel was adequate in 78.4 % of the examinations. The colon was not reached in 16.9 % of cases, and there were minor technical problems in 4.6 %. Relevant pathological findings were identified in 56.2 % of 151 patients with obscure bleeding or iron-deficiency anemia (64 % of whom received blood transfusions). The most common findings were angiodysplasia in 39.7 % of cases and ulcers of the small bowel in 7.3 %. In addition, individual cases of tumors and parasitic worms were detected. Seven of the 25 patients with suspected Crohn's disease (28 %) had the disease confirmed. Three of five patients with polyposis syndrome of the colon were found to have polyps in the small bowel. CONCLUSIONS: Wireless capsule endoscopy can be recommended as part of the routine work-up in patients with obscure bleeding or iron-deficiency anemia. In patients with Crohn's disease, the method may be helpful in establishing or ruling out the diagnosis.

Lipid-lowering therapy and cholesterol levels following acute myocardial infarction: a German study of 5361 patients.

BACKGROUND: Current studies on secondary prevention of cardiovascular events (CARE, LIPID, 4S) illustrate the necessity of an effective lipid-lowering therapy. An important part of secondary prevention is the prompt measurement of lipids following an infarct, to be able to start therapy as quickly as possible. AIMS: This study should show the general situation in the prescription of lipid-lowering drugs in patients with acute myocardial infarction (MI) and if there are gender differences in therapy and in the lipid parameters. The second aim was to determine the therapeutical conclusions for secondary prevention made in-hospital in patients with heart attacks. METHODS: Post-infarct lipid parameters (total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG) were examined in 5361 patients within 24 hours following an acute MI. Lipid parameters from 576 patients were measured again after 1 week. RESULTS: 80.1% of men under examination and 81.9% of the women had suffered from their first MI. Only 9% of all patients were already under lipid-lowering therapy before the MI. After the MI TC and LDL-C levels decreased significantly in a time-dependent manner. Around 50% of patients received lipid-lowering drug, or the recommendation of one, during their hospital stay. CONCLUSION: The range of TC values of the patients examined was comparable to those in the CARE and the 4S secondary prevention studies. It can therefore be assumed that the results of these studies are also applicable to Germany. Nevertheless, according to existing data, therapy with lipid-lowering drugs is currently unsatisfactory, even in secondary prevention.

[Colonoscopy and sigmoidoscopy in patients aged eighty years or older]. / Koloskopie und Sigmoidoskopie bei über achtzigjährigen Patienten.

BACKGROUND: The demographic development will lead to an increase in endoscopic examinations in elderly patients. Indications, feasibility and therapeutic consequences following detection of pathologic findings are important assessing the relevance of endoscopy in geriatric patients. METHODS: We analyzed all colonoscopies and sigmoidoscopies which were performed between January 1995 and December 2000 in patients older than 80 years. The parameters indication, sedation, colonoscopy completion rate, endoscopic findings, therapeutic consequences and complications were evaluated. RESULTS: A total of 951 endoscopies in patients older than 80 years (781 colonoscopies, 170 sigmoidoscopies; mean age 84.3 years) were performed. The most frequent indications were: abdominal pain (n = 144; 15 %), bleeding (n = 115; 12 %), constipation (n = 97; 10 %), anemia (n = 85; 9 %), and history of polyps (n = 78; 8 %). Sedation was used in 183 examinations (19 %), mostly with midazolam (n = 179). Colonoscopy was completed successfully to the coecum in 71 %. 214 examinations were unremarkable (23 %). Frequent pathologic findings were: diverticular disease (n = 396; 42 %), polyps (n = 256; 27 %), and colorectal carcinoma (n = 75; 8 %). Curative surgery was possible in 55 % and palliative surgery in 9 % of patients with colorectal carcinoma, respectively. A complication was observed in six patients (0.6 %), four bleedings following polypectomy, one perforation after dilatation of a stenotic tumor, and one transient neurologic deficit. CONCLUSIONS: Endoscopy of the lower gastrointestinal tract is feasible in geriatric patients with a low rate of complications. The low number of normal findings and the frequent diagnosis of colorectal carcinoma were remarkable. In spite of old age more than half of the patients with carcinoma could be operated curatively emphasizing the importance of endoscopic investigations in this age group.

Long term complications of inferior vena cava thrombosis.

AIM: To evaluate the long term outcome after paediatric inferior vena cava (IVC) thrombosis. METHODS: A combined retrospective and prospective study on infants and children with IVC thrombosis treated at Aachen and Maastricht University Hospitals between 1980 and 1999. RESULTS: Forty patients were enrolled, including four with preceding cardiac catheterisation, 18 with central venous saphenous lines, and an additional eight with umbilical venous catheters. Six patients died within three months of diagnosis; one patient was lost to follow up. Twelve of the remaining 33 patients had suffered from limited IVC thrombosis; during follow up (for up to nine years) none showed persisting caval obstruction (successful thrombolysis, n = 2; spontaneous recanalisation, n = 10). The remaining 21 patients presented with extensive IVC thrombosis. During follow up (for up to 18 years) complete restitution was found in only four cases (one thrombolysis, two surgery, one spontaneous recanalisation). Persisting iliac and/or caval venous obstruction occurred in 17 patients, including six with thrombolysis. Varicose veins were found in 12, and post-thrombotic syndrome in seven of these cases. According to Kaplan-Meier analysis, 30% of patients with persisting venous disease will develop post-thrombotic syndrome within 10 years of the thrombotic event. CONCLUSIONS: Infants and children with extensive IVC thrombosis are at high risk for persisting venous disease and serious long term complications. Prospective trials are urgently needed to establish effective treatment strategies and to improve long term prognosis. Central venous catheters, contributing to IVC thrombosis in the majority of cases reported here, should be inserted only if essential.

[Percutaneous transjugular thrombectomy in iliocaval thrombosis-- initial experience with a newly developed 12F balloon sheath]. / Perkutane transjuguläre Thrombektomie iliokavaler Thromben--Erster klinischer Einsatz einer neuentwickelten 12F Ballonschleuse.

PURPOSE: To evaluate the feasibility of percutaneous thrombectomy for the removal of floating iliocaval thrombi using a balloon sheath. MATERIALS AND METHODS: A newly developed balloon sheath (inner diameter: 12-F; outer diameter: 18-F) was tested in two patients with extensive iliocaval thrombosis. Mechanical thrombectomy was performed due to recurrent pulmonary embolism under therapeutic anticoagulation in antiphospholipid-antibody syndrome and, respectively, paraneoplastic thrombosis without a decrease of fresh thrombus mass in spite of pharmacological treatment. Via a transjugular access (20-F), the sheath was advanced retrogradely into the inferior vena cava. After blocking of the vessel, mechanical fragmentation was performed through the working channel coaxially, using a temporary vena cava filter as a rotating basket (max. diameter: 30 mm). Residual thrombus fragments were removed by aspiration. RESULTS: The thrombectomy balloon sheath tested allowed a complete removal of fresh thrombi after fragmentation. In addition, older clot material was obtained. Balloon occlusion prevented the central embolization of thrombus fragments. Clinical signs indicating pulmonary embolism were not seen. The fluid loss due to aspiration was negligible. CONCLUSIONS: The newly developed 12-F balloon sheath proved to be efficient for the extraction of large thrombi. Balloon occlusion safely prevented central embolization of thrombus fragments proximal to the sheath.

Feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance urography in children.

RATIONALE AND OBJECTIVES: To evaluate the feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance (MR) urography in children. METHODS: In a prospective study, 30 consecutive children, aged 3 weeks to 13.8 years, underwent MR urography. After intravenous injection of low-dose furosemide and gadopentetate dimeglumine, respiratory-gated, coronal, T1-weighted 3D-gradient-echo sequences were obtained at 1.5 T 5 to 30 minutes after contrast administration. Postprocessing of the data was performed using a maximum-intensity projection algorithm. In addition, precontrast half-Fourier rapid acquisition with relaxation enhancement MR urograms were obtained in 29 children. RESULTS: Respiratory-gated, T1-weighted MR urography was successfully performed in all children without the need for sedation. Compared with the final diagnosis, prospective analysis of MR urography images revealed the correct diagnosis in 56 of 58 pelvicaliceal systems (96%). The ureteral morphology was correctly evaluated in 59 of 64 ureters (92%). The method showed limited efficiency for evaluating nonfunctioning renal units. CONCLUSIONS: Respiratory-gated, gadolinium-enhanced T1-weighted MR urography is a feasible and effective diagnostic tool in the assessment of upper urinary tract morphology in children. It is especially useful in depicting nondilated collecting systems and ureters.

Unilateral absence of the left pulmonary artery associated with coronary-to-bronchial artery anastomosis.

Unilateral absence of the pulmonary artery and bronchial-to-coronary artery anastomosis are rarely described congenital vascular anomalies. The authors report a case of a 49-year-old female presenting with both anomalies. The presenting symptoms and pertinent diagnostic imaging are described, including conventional radiographs, angiography, computed tomography, and magnetic resonance imaging, and the therapeutic options available are discussed.

Recanalization of thrombosed dialysis access with use of a rotating mini-pigtail catheter: follow-up study.

PURPOSE: To evaluate the feasibility, efficacy, and safety of mechanical thrombectomy of occluded dialysis access with use of a rotating mini-pigtail catheter. MATERIALS AND METHODS: Thrombus was fragmented by mechanical action of the rotating pigtail tip (5-mm diameter), while the guide wire exited a sidehole at the pigtail curvature and served as a fixed rotation axis. Twenty-six procedures were performed in 22 patients (12 men, 10 women; mean age, 55.5 years). Native fistulas were treated in 15 instances, polytetrafluoroethylene (PTFE) grafts were treated in 11 instances. Average occlusion time was 20 hours +/- 13 (range, 5-46 hours), average occlusion length was 25.6 cm +/- 10.1 (range, 6-45 cm). Thrombus fragmentation was followed by balloon angioplasty of underlying stenoses. RESULTS: In all 26 procedures, the dialysis access was successfully declotted with subsequent dialysis using the access (clinical success rate, 100%). Handling of the mini-pigtail catheter was simple and rapid, regardless of whether a graft or a native fistula was treated. Average duration of the intervention was 118 minutes +/- 30. Mean primary patency was 165 days +/- 167. Primary patency rate was 82% at 30 days, 65% at 3 months, and 47% at 6 months. There was no evidence of complications due to the thrombus fragmentation procedure. CONCLUSION: The results suggest that declotting of occluded dialysis grafts and fistulas with the mini-pigtail catheter is as effective and safe as other more established percutaneous therapies. It may serve as an easy-to-handle, low-budget alternative to current thrombectomy devices.

Reduction of contrast material dose and artifacts by a saline flush using a double power injector in helical CT of the thorax.

OBJECTIVE: Our objective was to evaluate a combined method of contrast material bolus followed by saline solution flush for thoracic helical CT and statistical comparison with a uniphasic injection protocol. MATERIALS AND METHODS: Fifty patients underwent helical CT of the thorax using 60 ml of contrast material (370 mg I/ml) followed by flushing with 30 ml of physiologic saline solution. These 50 patients had been examined before using our previous protocol, 75 ml of the same contrast material without a subsequent saline solution. Mean attenuation values for both protocols were measured in the superior vena cava, the pulmonary trunk, and the ascending aorta. Image artifacts and mediastinal and hilar depiction were graded and compared. RESULTS: Mean attenuation values in the superior vena cava were considerably higher in the regimen without saline solution flush (459 H versus 352 H) and in the pulmonary trunk and the ascending aorta were almost identical for both protocols. Injection of saline solution diminished surrounding artifacts (p = 0.001). Grading results for the evaluation of mediastinal and hilar structures were not significantly different in the two protocols (p = 0.564). CONCLUSION: Injection of contrast material followed by a saline solution bolus using a double power injector when performing thoracic helical CT allows a 20% reduction of contrast material volume to 60 ml with a similar degree of enhancement. In addition, perivenous artifacts in the superior vena cava are significantly reduced.

[Catheter tract embolization after percutaneous transhepatic biliary intervention]. / Embolisation des Kathetertraktes nach perkutaner transhepatischer Gallenwegsintervention.

PURPOSE: Evaluation of the feasibility and efficacy of an embolization technique of the transhepatic tract after intervention, in order to prevent peritoneal bile leakage. PATIENTS AND METHOD: Twenty patients (mean age 62 yr) with malignant (17 cases) or benign (three cases) biliary obstruction were treated by percutaneous transhepatic biliary intervention (stent implantation in 17 cases). Mean diameter of the transhepatic tract was 3.2 +/- 0.6 mm. Tract embolization was performed 3.0 +/- 4.0 days after intervention by injecting Histoacryl-Lipiodol via a coaxial catheter-sheath system. RESULTS: Tract embolization was feasible in all cases and resulted in a continuous cast of the catheter tract. There were no signs or symptoms of peritonitis in any of the patients. One patient with stent occlusion developed a biliocutaneous fistula via the former tract after 60 days. CONCLUSION: After embolization of fresh transhepatic tracts there were no signs of leakage during follow-up of the patients. One case with biliocutaneous fistula shows that prevention of leakage is not permanent if biliary reobstruction occurs.

[Panorama ultrasound of the spinal canal with determination of the level of the conus medullaris in newborn infants and infants]. / Panorama-Ultraschall des Wirbelkanals mit Höhenlokalisation des Konus medullaris bei Neugeborenen und Säuglingen.

PURPOSE: To evaluate the utility of panoramic ultrasound in visualizing the spinal canal and the conus medullaris level in neonates and young infants. METHOD: 30 children (aged 2 days to 5 months, 2058-6660 g, 41-57 cm) underwent examination of the spinal canal. The children were examined by a single, continuous 9.0 MHz transducer movement from the cervico thoracic spine to the coccyx. A dedicated computer processor produced an extended field of view image in realtime mode. RESULTS: With panoramic ultrasound coverage of the thoracic, lumbar and sacral spinal canal on one extended image was possible. Visualization of the spinal cord, the conus medullaris level, the subarachnoid space, the cauda equina and the tip of the dural sac was easily accomplished in each child. An average of four trials was necessary to obtain an image of sufficient diagnostic quality. The conus level ranged from L1 to L3, the tip of the dural sac was localized at S1 to S3. CONCLUSIONS: Panoramic ultrasound offers nearly complete visualization of the spinal canal in children on one single extended field of view image. The conus medullaris level and the tip of the dural sac can easily be localized.

[A case-based and multi-media computer learning program on the topic of myocardial infarct, angina pectoris and mitral valve stenosis]. / Ein fallbasiertes, interaktives und multimediales Computerlernprogramm zum Thema Herzinfarkt, Angina pectoris und Mitralstenose.

BACKGROUND: Principles in the field of cognitive psychology and problem-based learning together with recent progress in multimedia technologies are providing the basis for the development of case-based and computer-assisted learning systems. With reference to the information-overload of theoretical and factual knowledge in medical education these programs can be an efficient tool to satisfy the current need for new, practical, skill-related forms of knowledge transfer. METHODS: Apple-Macintosh Computers were selected to develop interactive, multimedia patient-simulations on mitral stenosis, angina pectoris and myocardial infarction. INSTRUCTIONAL AIM AND CONTENTS: The user acquires knowledge and skills about the leading symptoms, differential diagnoses, the use and analysis of laboratory examinations and the process of diagnostic reasoning while working through the computer-simulated cases. PEDAGOGICAL DESIGN AND CONCLUSION: Important pedagogical principles associated with computer-assisted learning were employed in the program. Clinical situations can be simulated repeatedly and for every student in an authentic manner. Therefore the program can serve as a preparation for and a supplement to practical clinical education. Compared to conventional teaching media the development of instructional multimedia software requires a tremendous amount of time and resources. Thus, controlled studies are important to objectify the overall advantages such programs can have.

[Preoperative assessment of tumor aggressiveness in localized prostatic carcinoma]. / Präoperative Abschätzung der Tumoraggressivität beim lokalisierten Prostatakarzinom.

In 106 consecutive patients with localized prostate cancer digital rectal examination (DRE), preoperative prostate-specific antigen (PSA) determination and results of systematic sextant biopsies (TRUS 6Bx) of the prostate were analyzed for their value in the estimation of the aggressivity of tumors. In all patients with negative pelvic lymph nodes radical retropubic prostatectomy was performed. Tumor aggressiveness was defined as capsular penetration (pT2 versus pT3) or positive surgical margins in patients with pT3 tumors. Neither DRE nor preoperative PSA level was helpful in predicting capsular penetration or positive surgical margins. However, the number of positive core biopsies and the identification of Gleason 4 or 5 tumors within positive biopsy specimens correlated with capsular penetration and positive surgical margins. These results can be used to create a score, based on DRE, PSA, TRUS 6Bx, and Gleason 4 or 5, that might be helpful in predicting tumour aggressivity in patients with localized prostate cancer.