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Biomedical subjects

T Müller

Publications and source records attributed to T Müller.

At least 199 records · Page 11Linked to original sources
PubMed2000

Plasmapheresis in life-threatening verapamil intoxication.

Verapamil intoxications are life-threatening conditions with a far too often fatal outcome. In 2 patients, severe suicidal intoxication by 2.4 g and 9.6 g of verapamil orally resulted in life threatening hypotension and bradycardia with the need of heart-pacing and resuscitation. Plasmapheresis was started within less then 4 hours after intoxication and seemed to reduce the verapamil plasma concentration to less then 40%. A dramatic improvement of cardiovascular stability was already observed during plasmapheresis. In-vitro plasmapheresis was performed to verify the effectiveness of the extracorporeal detoxification. Verapamil was removed out of the blood by a clearance of 29.2 ml/min at blood flow of 200 ml/min. In conclusion, severe verapamil poisoning should be treated by early aggressive gut decontamination and an appropriate management of the haemodynamic complications. In case of lack of effectiveness for stabilisation, plasmapheresis can reduce verapamil related life threatening symptoms and bridge the time for the hepatic detoxification.

Acute Disease↗
PubMed2000

Transient classical swine fever virus infection in wild boar piglets partially protected by maternal antibodies.

An experimental study was conducted to investigate the clinical course of classical swine fever (CSF) in wild boar piglets partially protected by maternal antibodies. Five healthy wild boar piglets with a low serum titre of colostral antibodies against CSF virus were challenged with virulent CSF virus at the age of three months. Apart of reduced food intake and diarrhoea no major clinical symptoms were noticed after challenge. These signs were seen during the second and third week of infection, afterwards the piglets recovered completely. CSF virus could be re-isolated from blood samples taken on day 12 and day 19 post challenge. From blood samples taken later on and from the organ material taken at post mortem examinations no CSF virus could be isolated anymore. It can be concluded that the presence of maternal antibodies influences the clinical course of CSF in terms that the outcome is rather transient than lethal. Such wild boar could play a crucial role in the spread of CSF virus and might contribute to the maintenance of long lasting epizootics.

Animals↗
PubMed2000

Schedule-dependent antagonism of gemcitabine and cisplatin in human anaplastic thyroid cancer cell lines.

Anaplastic thyroid carcinoma (ATC) affects primarily elderly patients, with a median survival of 4-12 months after diagnosis. Presently, under clinical investigation the combination of cisplatin (CDDP) and gemcitabine (GEM) has promising activity in several of human tumor types. To develop new approaches for therapy of ATC, we evaluated the antineoplastic activity of GEM and CDDP alone (1-h and 24-h drug exposure) or in combination in the ATC cell lines SW1736, 8505C, C643, and HTh74. IC50 values were determined by the sulforhodamine B assay, activity was evaluated by the relative antitumor activity (RAA) and drug interaction assessed by isobologram analysis. GEM seemed to be active in ATC, with RAA ranging from 12-114 and CDDP only modestly active (RAA, 0.24-1.4). In four different drug schedules tested, the drug combination was additive when GEM preceded CDDP exposure (combination index, approximately 1), whereas when CDDP preceded GEM exposure the combination was significantly antagonistic (combination index, >1). In SW1736 and 8505C cells, we observed a strong S phase arrest and DNA synthesis inhibition 24 h after a 1-h exposure to an IC50 of CDDP. On the basis of molecular drug targets, cell cycle arrest points, and DNA synthesis inhibition, a model was developed to explain the interaction observed for the combination of GEM and CDDP. In conclusion, GEM shows promising cytostatic activity in ATC. Interaction of GEM and CDDP was schedule and dose dependent, favoring a regime in which GEM is followed by CDDP. Additionally, our model system suggests that DNA-synthesis inhibition and S phase arrest may be important determinants for the drug interaction between GEM and CDDP.

Antineoplastic Agents↗
PubMed2000

On a complex anastomosis of the glossopharyngeal nerve in humans.

The glossopharyngeal nerve shows anastomoses with the facial nerve and the sympathetic nervous system. One anastomosis extends from the interconnected stylopharyngeal branches, immediately after having perforated the muscle towards the base of skull. Cranially, varying targets of the ascending nerve can be discriminated: 1) The temporal bone. 2) The facial nerve. 3) The sympathetic nerve plexus of the internal carotid nerve. This complex anastomosis was now studied under the dissecting microscope in more detail. The investigation revealed a more complicated distribution pattern of the anastomotic nerve than previously assumed, i.e. the existence of a solitary ascending branch could only be proved in a minority of cases (seven of twenty individuals). In the majority, a delicate nerve plexus could be visualized (thirteen of twenty individuals). In the cases of an anastomosis with the facial nerve, the stylohyoid branch was observed to be the main target of the ascending nerve. Also, connections with the internal carotid nerve were seen. In addition, delicate endings of the branches were demonstrated ramifying in the styloid process or penetrating the temporal bone at other sites. The histological demonstration of ganglion cells within the ascending nerve or nerve plexus suggests parasympathetic and sensoric functions for this anastomosis.

Facial Nerve↗
PubMed1999

A role of the cryptic gene in the correct establishment of the left-right axis.

During vertebrate embryogenesis, a left-right axis is established. The heart, associated vessels and inner organs adopt asymmetric spatial arrangements and morphologies. Secreted growth factors of the TGF-beta family, including nodal, lefty-1 and lefty-2, play crucial roles in establishing left-right asymmetries [1] [2] [3]. In zebrafish, nodal signalling requires the presence of one-eyed pinhead (oep), a member of the EGF-CFC family of membrane-associated proteins [4]. We have generated a mutant allele of cryptic, a mouse EGF-CFC gene [5]. Homozygous cryptic mutants developed to birth, but the majority died during the first week of life because of complex cardiac malformations such as malpositioning of the great arteries, and atrial-ventricular septal defects. Moreover, laterality defects, including right isomerism of the lungs, right or left positioning of the stomach and splenic hypoplasia were observed. Nodal gene expression in the node was initiated in cryptic mutant mice, but neither nodal, lefty-2 nor Pitx2 were expressed in the left lateral plate mesoderm. The laterality defects observed in cryptic(-/-) mice resemble those of mice lacking the type IIB activin receptor or the homeobox-containing factor Pitx2 [6] [7] [8] [9], and are reminiscent of the human asplenic syndrome [10]. Our results provide genetic evidence for a role of cryptic in the signalling cascade that determines left-right asymmetry.

Alleles↗
PubMed1999

Transcranial magnetic stimulation compared with upper motor neuron signs in patients with amyotrophic lateral sclerosis.

If patients with amyotrophic lateral sclerosis (ALS) present without upper motor neuron signs (UMNS) they do not meet current ALS research criteria. To compare how sensitively degeneration of upper motor neurons is detected clinically and by transcranial magnetic stimulation, 35 patients with ALS were studied. Nineteen patients had definite UMNS, nine patients had probable UMNS, and seven patients had no UMNS. Cortex, cervical nerve roots, and lumbar plexus were stimulated with a magnetic stimulator. Compound muscle action potentials from abductor digiti minimi and from anterior tibial muscles were recorded with surface electrodes. Responses to transcranial magnetic stimulation were considered abnormal if central motor conduction time was above the 99% upper limits or if there was no response to cortical but to peripheral stimulation. In all patients with definite UMNS central motor conduction was abnormal. In patients with probable UMNS it was abnormal in 67%, and in patients without UMNS it was abnormal in 71%. Abnormality of central motor conduction was neither correlated with the duration nor with the severity of the disease. The high rate of abnormalities of central motor conduction found in patients with ALS but without definite UMNS suggests that, in these patients, the diagnosis of ALS can be made more reliably if transcranial magnetic stimulation studies are performed.

Action Potentials↗
PubMed1999

The spatio-temporal dynamics of a post-vaccination resurgence of rabies in foxes and emergency vaccination planning.

We used a simulation model to study the spatio-temporal dynamics of a potential rabies outbreak in an immunized fox population after the termination of a long-term, large-scale vaccination program with two campaigns per year one in spring and one in autumn. The 'worst-case' scenario of rabies resurgence occurs if rabies has persisted at a low prevalence despite control and has remained undetected by a customary surveillance program or if infected individuals invade to the control area. Even if the termination of a vaccination program entails such a risk of a subsequent new outbreak, prolonged vaccination of a wild host population is expensive and the declining cost-benefit ratio over time eventually makes it uneconomic. Based on the knowledge of the spatio-temporal dynamics of a potential new outbreak gained from our modelling study, we suggest "terminating but observing" to be an appropriate strategy. Simulating the decline of population immunity without revaccination, we found that a new outbreak of rabies should be detected by customary surveillance programs within two years after the termination of the control. The time until detection does not depend on whether vaccination was terminated within the fourth, fifth or sixth years of repeated biannual campaigns. But it is faster if the program was completed with an autumn campaign (because next-year dispersal then occurs after a noticeable decrease in population immunity). Finally, if a rabid fox is detected after terminating vaccination, we determine a rule for defining a circular hazard area based on the simulated spatial spread of rabies. The radius of this area should be increased with the time since the last vaccination campaign. The trade-off between the number of foxes potentially missed by the emergency treatment and the cost for the emergency measures in an enlarged hazard area was found.

Animals↗
PubMed1999

Non-Indian childhood cirrhosis.

Copper is an essential trace element for sustaining life. However, copper in excess is highly toxic and elevated copper concentrations in cells have been associated with several diseases, including non-Indian childhood cirrhosis (NICC) in man and copper toxicosis in Bedlington terriers. NICC and copper toxicosis in Bedlington terriers are phenotypic very similar to Wilson disease and Indian childhood cirrhosis. Recently, the gene underlying Wilson disease (ATP7B) as well as copper transport genes hCTR1, hCTR2 and ATOX1 have been excluded as candidates for NICC in man and copper toxicosis in Bedlington terriers. Currently, a genome wide screen is being carried out to localize the NICC gene. Isolation of the NICC gene and defining its pathophysiology will significantly expand our insight into copper metabolism in man, which, at present, is largely limited. The availability of a dog mutation with phenotypic similarities to NICC will open up new lines of research for studying the disease if it proves to be homologous to NICC but will still represent an important addition to the list of genes determining copper disease in mammals if it doesn t.

Animals↗
PubMed1999

Nigral endothelial dysfunction, homocysteine, and Parkinson's disease.

We found increased levels of atherosclerosis-inducing homocysteine in parkinsonian patients with long-term application of levodopa compared with previously untreated parkinsonian patients and controls. We conclude that antiparkinsonian treatment with levodopa promotes occurrence of vascular disease in Parkinson's disease.

Aged↗
PubMed1999

Single micro electrode dielectrophoretic tweezers for manipulation of suspended cells and particles.

Cells or particles in aqueous suspension close to a single capacitively coupled micro electrode (CCME) driven with high frequency electric fields experience dielectrophoretic forces. The effects near the CCME can be used for trapping and manipulation of single cells using externally metallised glass pipettes and might be used to develop a microscope based on force or capacitance measurements in conductive media.

Biotechnology↗
PubMed1999

Phosphorylation and free pool of beta-catenin are regulated by tyrosine kinases and tyrosine phosphatases during epithelial cell migration.

Cell migration requires precise control, which is altered or lost when tumor cells become invasive and metastatic. Although the integrity of cell-cell contacts, such as adherens junctions, is essential for the maintenance of functional epithelia, they need to be rapidly disassembled during migration. The transmembrane cell adhesion protein E-cadherin and the cytoplasmic catenins are molecular elements of these structures. Here we demonstrate that epithelial cell migration is accompanied by tyrosine phosphorylation of beta-catenin and an increase of its free cytoplasmic pool. We show further that the protein-tyrosine phosphatase LAR (leukocyte common antigen related) colocalizes with the cadherin-catenin complex in epithelial cells and associates with beta-catenin and plakoglobin. Interestingly, ectopic expression of protein-tyrosine phosphatase (PTP) LAR inhibits epithelial cell migration by preventing phosphorylation and the increase in the free pool of beta-catenin; moreover, it inhibits tumor formation in nude mice. These data support a function for PTP LAR in the regulation of epithelial cell-cell contacts at adherens junctions as well as in the control of beta-catenin signaling functions. Thus PTP-LAR appears to play an important role in the maintenance of epithelial integrity, and a loss of its regulatory function may contribute to malignant progression and metastasis.

Animals↗
PubMed1999

R- and S-salsolinol are not increased in cerebrospinal fluid of Parkinsonian patients.

Various investigators address an augmented synthesis of tetrahydroisoquinolines, such as salsolinol (SAL), or an increased N-methylation of these compounds as putative pathophysiologic mechanisms in Parkinson's disease (PD). Objectives of this study were (1) the evaluation of a putative elevation of enantiomers (R-, S-) of SAL and (2) the investigation of relations between these metabolic precursors of neurotoxic N-methylated-SAL (NMSAL) and dopamine in cerebrospinal fluid of untreated de-novo Parkinsonian patients and age- and sex-matched healthy controls. Levels of R- and S-SAL and dopamine did not significantly (R-SAL: P = 0.75, S-SAL: P = 0.69, dopamine: P = 0.46) differ and dopamine did not correlate to R-SAL and S-SAL in both groups. We conclude, that central accumulation of R-NMSAL, which is neurotoxic to dopaminergic nigrostriatal neurons, is not due to elevated synthesis of R-SAL and/or S-SAL in PD.

Adult↗
PubMed1999

Increased susceptibility to sporadic Parkinson's disease by a certain combined alpha-synuclein/apolipoprotein E genotype.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders affecting about 1% of Western populations older than age 50. The pathological hallmark of PD are Lewy bodies, that is, intracytoplasmic inclusion bodies in affected neurons of the substantia nigra. Recently, alpha-synuclein (alpha-SYN) has been identified as the main component of Lewy bodies in sporadic PD, suggesting involvement in neurodegeneration via protein accumulation. The partially overlapping pathology of PD and Alzheimer's disease, as well as striking structural similarities of alpha-SYN and apolipoprotein E, which is a major risk factor for late-onset Alzheimer's disease, prompted us to investigate the influence of different alpha-SYN and apolipoprotein E alleles for developing sporadic PD. We performed association studies in 193 German PD patients and 200 healthy control subjects matched for age, sex, and origin. A polymorphism in the promoter region of the alpha-SYN gene (NACP-Rep1) as well as of the closely linked DNA markers D4S1647 and D4S1628 revealed significant differences in the allelic distributions between PD patients and the control group. Furthermore, the Apo epsilon4 allele but not the Th1/E47 promoter polymorphism of the apolipoprotein E gene was significantly more frequent among early-onset PD patients (age at onset, <50 years) than in late-onset PD. Regarding the combination of the Apo epsilon4 allele and allele 1 of the alpha-SYN promoter polymorphism, a highly significant difference between the group of PD patients and control individuals has been found, suggesting interactions or combined actions of these proteins in the pathogenesis of sporadic PD. PD patients harboring this genotype have a 12.8-fold increased relative risk for developing PD during their lives.

Aged↗
PubMed1999

Clinical efficacy of budipine in Parkinson's disease.

The lipophilic t-butyl analog of 1-alkyl-4,4-diphenyl piperidine, budipine, possesses a polyvalent spectrum of mechanisms of action. Budipine experimentally increased the brain content of norepinephrine, serotonine, dopamine and histamine in reserpine treated rats. Budipine did not alter the receptor affinity of these neurotransmitters but antagonizes the effect of NMDA at its receptor binding site in vitro. Budipine reduced MPP+ toxicity in the nigrostriatal system of mice. This complex pharmacologic profile is not comparable to the one of convenient antiparkinsonian drugs. In clinical trials budipine reduced tremor, akinesia and rigidity. Budipine induced a relevant additional positive effect in patients with an optimal dopaminergic therapy based on levodopa and dopamine agonists, such as bromocriptine. Current available data suggest that the need for levodopa application in early stages of the disease may be postponed by budipine and that the long-term application of budipine may induce a levodopa-sparing effect.

Animals↗
PubMed1999

Dielectric single particle spectroscopy for measurement of dispersion.

Measuring the frequency-dependent behaviour of single particles or biological cells in inhomogeneous and/or rotating electric fields is a sensitive method for characterising their dielectric properties. This technique is able to detect broad dispersion in the megahertz range of homogeneous artificial Sephadex G15 spheres. Recent progress has opened up the possibility of carrying out dielectric spectroscopy in cell culture media. Dielectrophoretic and electrorotational spectra of different cells in media of varying conductivity can only be explained by the introduction of dispersive cell compartments. The cytoplasm of animal cells typically exhibits a broad dispersion around 15 MHz and there is evidence for membrane dispersion around 50 MHz.

Animals↗
PubMed1999

Detection of tolcapone in the cerebrospinal fluid of parkinsonian subjects.

The cerebral availability of the peripherally and centrally acting catechol-O-methyltransferase (COMT) inhibitor tolcapone is not known in humans. Therefore, we determined the concentration of tolcapone in cerebrospinal fluid (CSF) of 12 parkinsonian subjects 1-4 h after oral application of 200 mg of the drug. The mean concentration was 56.4+/-35.5 nmol/l (mean +/- SD). This concentration was calculated to cause 75.2+/-15% (mean +/- SD) inhibition of COMT in CSF. Thus, tolcapone efficiently inhibits COMT after crossing the blood-brain barrier in humans.

Administration, Oral↗