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G Fischer

Publications and source records attributed to G Fischer.

At least 37 records · Page 2Linked to original sources
PubMed2004

Radio and plasma wave observations at Saturn from Cassini's approach and first orbit.

We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 +/- 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.

Journal Article↗
PubMed2004

Effects of weak 16 3/2 Hz magnetic fields on growth parameters of young sunflower and wheat seedlings.

Previous studies on effects of magnetic fields on plants focussed on the power frequencies (50-60 Hz), but in Austria and Germany electric railways are powered by a frequency of 16 2/3) Hz. In the present study, sunflower and wheat seedlings were exposed to 16 2/3 Hz sinusoidal 20 muT (rms) vertical magnetic fields. Seeds were germinated in a germination roll and grown for 12 days under continued exposure. Seven series with sunflower and six series with wheat were done over 2 years. Sunflower seedlings exposed to experimental magnetic field showed small, but significant increases in total fresh weights, shoot fresh weights, and root fresh weights, whereas dry weights and germination rates remained unaffected. Experimentally treated wheat exhibited marginally (but significantly) higher root fresh and dry weights, total fresh weights, and higher germination rates.

Electromagnetic Fields↗
PubMed2004

Ventricular surface activation time imaging from electrocardiogram mapping data.

Non-invasive imaging of cardiac electrophysiology provides a non-invasive way of obtaining information about electrical excitation. An iterative algorithm based on a general regularisation scheme for non-linear, ill-posed problems in Hilbert scales was applied to the electrocardiographic inverse problem, imaging the ventricular surface activation time (AT) map. This method was applied to electrocardiographic data from a 31-year-old healthy volunteer and a 24-year-old patient suffering from a Wolff-Parkinson-White (WPW) syndrome. The objective was to evaluate non-invasive AT imaging of an autonomous sinus rhythm and to quantify the localisation error of non-invasive AT imaging by localising the accessory pathway of the WPW syndrome and a pacing site for left ventricle pacing. The distances between the invasive and non-invasive localisation of the pacing site and the accessory pathway were 8 mm and 5 mm. The clinical case presented, shows that this non-invasive AT imaging approach may enable the reconstruction of single focal events with sufficient accuracy for potential clinical application.

Adult↗
PubMed2004

Malignant pleural and pericardial effusion in invasive breast cancer: impact of the site of the primary tumor.

BACKGROUND: Malignant effusion in invasive breast cancer, either pleural or pericardial, is associated with a poor survival rate. We investigated the role of the location of invasive breast cancer in developing malignant pleural or pericardial effusion. METHODS: Three thousand eight hundred and fifty six women with a history of invasive breast cancer between 1960 and 1994 were analyzed in a retrospective study. Two hundred and six patients (5.34%; group A) developed malignant pleural and/or pericardial fluid as the first visible clinical sign of distant metastasis. A control group of 206 patients (group B) without malignant effusions were matched in terms of clinical and pathological characteristics. The two groups were compared in respect of the location of the primary tumor. Fifty patients in group A (n = 50; 24.2%) had tumors in the inner quadrants, 83 patients (n = 83; 40.3%) in the outer quadrants, and 13 patients (n = 13; 6.3%) in a central location. No data were available for 60 patients (n = 60; 29.1%). In group B, 12 patients (n = 12; 5.9%) had tumors in the inner quadrants, 140 patients (n = 140; 68.0%) in the outer quadrants, 14 patients (n = 14; 6.8%) had centrally located tumors, while no data were available for 40 patients (n = 40; 19.4%). Invasive ductal carcinomas (IDC) located in the inner quadrants were highly significantly associated with increased pleural or pericardial effusion as the first site of distant metastasis (p <or= 0.0001; chi-square tests). CONCLUSION: IDC in the inner quadrants were associated with a 4-fold higher rate of malignant pleural or pericardial effusions. Further studies will have to determine whether tumor location is a criterion for more aggressive adjuvant therapy.

Austria↗
PubMed2004

[Erroneous X-ray dose measurements in paediatric cardiac investigations].

According to national and international rules the x-ray exposure of cardiac catheter examinations have to be measured. For a Philips Integris angiographic system used for paediatric heart catheterization we found severe errors in the indicated time of fluoroscopy and total dose area product ( DAP) both for fluoroscopy and radiography. Fluoroscopy times shorter than 6 seconds and DAPs smaller than 0.1 Gy cm (2) are ignored and not considered in the indicated total fluoroscopy time and the fluoroscopic and radiographic DAPs. This error leads to a systematic underestimation of the risk of radiation-induced cancer especially with infants and children.

Child↗
PubMed2004

[Glossary on patient safety -- a contribution to on-target-definition and to appreciate the subjects of "patient safety"].

Since the release of the report "To Err is Human" by the American Institute of Medicine (IOM) the subject "Medical Risks, Errors and Patient Safety" has gained increasing interest in literature. In Germany, neither extensive statistics nor generally significant epidemiological studies regarding common errors associated with damages caused to patients' health exist. In recent years the subject has become increasingly interesting both in specialist discussion and it the lay press; it has become evident that the different use of terms, especially those originating from the Anglo-Saxon language, can lead to misunderstandings. Hence, as one of the first steps of its action programme, the expert panel "Patient Safety" of the German Agency for Quality in Medicine has compiled a glossary of technical terms to provide adequate support to the discussion this important subject of nomenclature.

Germany↗
PubMed2004

Towards clinical bioinformatics: advancing genomic medicine with informatics methods and tools.

OBJECTIVES: To summarize the challenges facing clinical applications in the light of growing research results in genomic medicine and bioinformatics. METHODS: Analysis of the contents of the Yearbook of Medical Informatics 2004 of the International Medical Informatics Association (IMIA). RESULTS: The Yearbook of Medical Informatics 2004 includes 32 articles selected from 22 peer-reviewed scientific journals. A special section on clinical bioinformatics highlights recent developments in this field. Several guest editors review the promises and limitations of available methods and resources from biomedical informatics that are relevant to clinical medicine. Integrated data and knowledge resources are generally regarded to be central and key issues for clinical bioinformatics. Further review papers deal with public health implications of bioinformatics, knowledge management and trends in health care education. The Yearbook includes for the first time a section on the history of medical informatics, where the significant impact of the Reisensburg protocol 1973 on international health and medical informatics education is examined. CONCLUSIONS: Close collaboration between bioinformatics and medical informatics researchers can contribute to new insights in genomic medicine and contribute towards the more efficient and effective use of genomic data to advance clinical care.

Computational Biology↗
PubMed2003

Fracture properties of the human mandible.

A total of seven human mandibles were struck to breaking point under standardised conditions using a pendulum. The cortical deformation for two impact directions was measured with strain gauge strips located at eight defined sites. Fronto-median impacts led to mostly bilateral and always multiple fractures in the posterior area of the bone, especially in the collum and the condyle. The fracture threshold was between 2.5 and 3.1 kN. Lateral impact caused fractures near the impact area as direct fractures of the ipsilateral corpus. Mainly single and double fractures were observed. For lateral impact the fracture threshold was between 0.6 and 0.8 kN.

Adult↗
PubMed2003

Deformation characteristics of the human mandible in low impact experiments.

A total of 11 human mandibles were subjected to physical impacts under standardised conditions. Two impact sites and directions were tested and the impact load was varied in four steps. Two occlusional strengths were applied and the influence of simulated soft tissue covering was recorded. The deformation of the bones was measured using strain gauge strips located at eight defined sites. In a series of frontal to occipital impacts the frontal areas and the collum showed the largest length changes. Increasing impact intensities led to a proportional increase of the length changes. An increase of the occlusional strength was either protective (at the collum) or it increased the deformation (frontal area). The soft tissue covering was only partly protective. Lateral impact was characterised by a compression on the side of the impact and stretching on the other side only. The intensity and speed of deformation increased with increasing distance from the site of impact. A fixed occlusion caused an increase of compression at the site of impact and an increasing stretching in the frontal part of the bone and at the opposite collum.

Adult↗
PubMed2003

Regulation of peptide bond cis/trans isomerization by enzyme catalysis and its implication in physiological processes.

In some cases, the slow rotational movement underlying peptide bond cis/trans isomerizations is found to control the biological activity of proteins. Peptide bond cis/trans isomerases as cyclophilins, Fk506-binding proteins, parvulins, and bacterial hsp70 generally assist in the interconversion of the polypeptide substrate cis/trans isomers, and rate acceleration is the dominating mechanism of action in cells. We present evidence disputing the hypothesis that some of the molecular properties of these proteins play an auxiliary role in enzyme function.

Catalysis↗
PubMed2003

Development of a liquid chromatographic/tandem mass spectrometric assay for a new endothelin receptor antagonist, and its application to dog plasma samples generated after simultaneous i.v. and p.o. administration of the unlabeled and deuterium-labeled forms of this antagonist.

An assay was developed and applied to determine the bioavailability of a new endothelin receptor antagonist after simultaneous p.o. and i.v. administration of the drug and its stable isotope-labeled analogue. The drug, its main metabolite and the stable isotope-labeled analogues of the drug and the main metabolite were quantified in dog plasma samples using a structural analogue as internal standard. In addition to the calculation of the bioavailability, the formation of the metabolite after p.o. and i.v. administration could be followed independently. The assay covered the concentration range 0.25-1000 ng ml(-1) using sample aliquots of only 50 micro l. Plasma samples were processed after protein precipitation with on-line solid-phase extraction, narrow-bore high-performance liquid chromatography and subsequent tandem mass spectrometric detection. Detection was accomplished with ionspray in the positive ion selected reaction monitoring mode. The inter-assay precision and accuracy of the assay were in the range 4.7-14.2% and 90.3-113.3%, respectively, and the intra-assay precision and accuracy were in the range 1.4-11.5% and 88.4-112.5%, respectively. The fragmentation of the drug was investigated and showed an unexpected shift of a methyl group. Data from MS(n), medium-resolution exact mass tandem mass spectrometry and H-D exchange experiments were employed to clarify the mechanism.

Administration, Oral↗
PubMed2003

Changes in peptidyl-prolyl cis/trans isomerase activity and FK506 binding protein expression following neuroprotection by FK506 in the ischemic rat brain.

FK506 is an immunosuppressant also showing neuroprotection following cerebral ischemia. FK506 binds to intracellular proteins (FKBP) which have a wide range of functions but have in common the peptidyl-prolyl cis/trans isomerase activity. Following transient focal ischemia, we have analyzed the expression of FKBP12, 52 and 65 and the total FKBP enzyme activity. Furthermore, we have investigated the effect of FK506 on signal transduction in neurons and perfusion changes in the infarct area. After 90 min of transient middle cerebral artery occlusion in male rats the expression of FKBP12, 52 and 65 was analyzed by Western blot in FK506-treated and control animals and the peptidyl-prolyl cis/trans isomerase activity was determined. Magnetic resonance imaging was used to measure tissue perfusion, development of vasogenic edema and infarct size. To investigate the neuronal stress signal cascade, activating transcription factor 2 (ATF-2), Fas-ligand (Fas-L) and c-Jun expression and phosphorylation were analyzed by immunohistochemistry. FK506 decreased the cerebral infarct volume by 53% and reduced the cytotoxic edema. The total FKBP enzymatic activity in the infarct area was increased and blocked dose dependently by FK506. FKBP expression was selectively up-regulated by cerebral ischemia. FK506 treatment does not influence the expression patterns. c-Jun phosphorylation in neurons of the peri-infarct area and Fas-L expression was reduced by FK506 treatment whereas ATF-2 expression was preserved. Cerebral ischemic damage to the brain was reduced by FK506. It was shown for the first time that neuroprotection by FK506 also included the suppression of the cerebral peptidyl-prolyl cis/trans isomerase activity of FKBP in vivo whereas the expression levels of FKBP12, 52 and 65 following ischemia changed slightly and FK506 treatment does not suppress the expression patterns. However, changes of FKBP enzymatic activity result in suppression of the stress cell body response in the peri-infarct area as observed by suppression of c-Jun phosphorylation and Fas-L expression.

Activating Transcription Factors↗
PubMed2003

Autoimmune diseases in vitiligo: do anti-nuclear antibodies decrease thyroid volume?

An increased prevalence of autoimmune thyroiditis (AT) in vitiligo patients is well known. The aim of this study was firstly, to evaluate the clinical course of patients with both vitiligo and AT and secondly, to identify additional autoimmune disorders affecting the thyroid gland in a large cohort of vitiligo patients. We analysed a study group of 106 vitiligo patients and 38 controls. A detailed thyroid examination including sonography was performed in all study participants. In addition, the study participants were HLA typed and screened for various autoimmune disorders. AT was significantly more frequent in vitiligo patients than in controls (21%versus 3%; P < 0.01). In 12 of the 22 patients with AT, vitiligo was the initial disease preceding AT by 4-35 years. In the other 10 patients with AT, both vitiligo and AT were diagnosed within one year. There were two individuals with diabetes mellitus type 1 and a single patient with Addison's disease. Anti-nuclear antibody (ANA), anti-smooth muscle cell antibody, and parietal cell antibody levels occurred with a similar frequency in patients and controls. In all vitiligo patients with both elevated ANA levels and AT (n = 6), the atrophic but not the goitrous variant was diagnosed. These vitiligo patients with both AT and elevated ANA levels had a significantly smaller thyroid volume compared to the vitiligo patients with AT whose ANA levels were normal (6.7 +/- 4.5 ml versus 13.4 +/- 9.1 ml, respectively; P < 0.05). The same was found in the entire study group: Thyroid volume of all vitiligo patients (with or without concomitant AT) was significantly smaller in the presence of ANA (6.9 +/- 5.3 versus 10.5 +/- 5.9 ml, respectively; P < 0.05). However, this phenomenon was not observed in the control group. There was a trend for a decreased frequency of HLA-DR3 (6.7%versus 23%) in our study group, but after correction for the number of comparisons, no HLA-allele was statistically significant associated neither with vitiligo nor with multiple autoimmune diseases in our patient sample. Our findings suggest that AT is the most frequent autoimmune disease associated with vitiligo. In our patients, AT presented simultaneously or after the onset of vitiligo but not before. Elevated ANA levels were associated with the atrophic variant of AT and may affect the volume of the thyroid gland, and there was no statistically significant association with the HLA system.

Adolescent↗
PubMed2003

Experience with transcatheter closure of secundum atrial septal defects using the Amplatzer septal occluder: a single centre study in 236 consecutive patients.

AIM: To evaluate the safety and efficacy of transcatheter closure of secundum atrial septal defects (ASD) with the Amplatzer septal occluder. METHODS: 236 consecutive patients with a significant ASD (age 6 months to 46 years, median 5 years; body weight 6.5-79 kg, median 18 kg) were considered for transcatheter closure with the Amplatzer septal occluder; 18 patients with defects that were too large or with a deficient inferior margin were excluded from attempted transcatheter closure after initial transthoracic (4) or transoesophageal echocardiography (14). RESULTS: At cardiac catheterisation, devices were not implanted in 18 patients because the stretched diameter of the ASD was too large (4), the device was unstable (4), compromised the mitral valve (1), or obstructed the upper right pulmonary vein (1); eight patients with additional systemic or pulmonary vein anomalies (5) or a Qp:Qs less than 1.5 (3) were excluded after angiographic and haemodynamic assessment. Thus ASD closure was done successfully in 200 patients (procedure time 25-210 minutes, median 66 minutes; fluoroscopy time 2.5-60 minutes, median 12 minutes), among whom 22 had multiple ASDs (14) or a septal aneurysm (8). The diameter of the devices ranged between 6-34 mm. Severe procedure related complications (retroperitoneal bleeding, air embolism) occurred in two cases. At follow up (33 days to 4.3 years, median 2.3 years) complete closure was documented in 94%, with a trivial residual shunt in 12 patients. CONCLUSIONS: The Amplatzer septal occluder is very efficient and offered interventional ASD closure in 84.7% of our group of consecutive patients, with excellent intermediate results.

Adolescent↗
PubMed2003

Medical informatics and the quality of health: new approaches to support patient care - findings from the IMIA Yearbook of Medical Informatics 2003.

OBJECTIVES: The Yearbook of Medical Informatics is published annually by the International Medical Informatics Association (IMIA) and contains a selection of excellent papers on medical informatics research which have been recently published (http://www. yearbook.uni-hd.de). The 2003 Yearbook of Medical Informatics took as its theme the role of medical informatics for the quality of health care. In this paper, we will discuss challenges for health care, and the lessons learned from editing IMIA Yearbook 2003. RESULTS AND CONCLUSIONS: Modern information processing methodology and information and communication technology have strongly influenced our societies and health care. As a consequence of this, medical informatics as a discipline has taken a leading role in the further development of health care. This involves developing information systems that enhance opportunities for global access to health services and medical knowledge. Informatics methodology and technology will facilitate high quality of care in aging societies, and will decrease the possibilities of health care errors. It will also enable the dissemination of the latest medical and health information on the web to consumers and health care providers alike. The selected papers of the IMIA Yearbook 2003 present clear examples and future challenges, and they highlight how various sub-disciplines of medical informatics can contribute to this.

Delivery of Health Care↗
PubMed2003

[Strategies and targets for establishing a multicenter trial: "Identification of indoor relevant moulds"].

Quality control is universally recognised as fundamentally important in ensuring that diagnostic laboratories are performing appropriate tests at acceptable levels of competence. Therefore, the working group "Quality assurance--Fungi in Indoor Environments" which was initiated by the Public Health Service Baden-Württemberg (LGA BW) started with the external quality assurance in the diagnosis of indoor fungi in autumn 2001. Up to now we carried out the third mailing based on pure cultures. The results are reported and will be discussed. Exchanging experience on the international level is intended.

Air Pollution, Indoor↗