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Biomedical subjects

M Fuchs

Publications and source records attributed to M Fuchs.

At least 73 records · Page 4Linked to original sources
PubMed2001

RNA editing in higher plant plastids: oligoribonucleotide SSCP analysis allows the proof of base conversion directly at the RNA level.

Plastid RNA editing of a number of transcripts at specific sites changes genomically encoded cytidines to nucleosides, which act like uridines in RT-PCR analyses. To study plastid-editing directly at the RNA level, we established a single-strand conformational polymorphism assay for the discrimination of small RNA molecules. The electrophoretic mobility of a oligoribonucleotide resulting from a RNase T1-digested and edited plastid mRNA was shown to be identical with a control RNA molecule containing a uridine at the editing site, whereas the unedited RNA behaved like a RNA molecule containing a cytidine at the respective position.

Chromosome Mapping↗
PubMed2001

Conscientious metabolic monitoring on a patient with hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome undergoing anaesthesia.

Currently we know not more than 50 patients who show an interesting combination of increased plasma ornithine concentrations, postprandial hyperammonemia, and homocitrullinuria (HHH-syndrome). Since exact knowledge of this severe, although rare syndrome is important for any perioperative or intensive medical treatment concerning therapy and progression of the disease, we report a comprehensive study on a 32-year old woman with this rare multifaceted disorder who had to undergo general anaesthesia. For the first time amino acid status in plasma, urine, cerebrospinal fluid and especially polymorphonuclear leucocytes, which in the investigation showed to be valuable tool for evaluating amino acid metabolism in nucleated cells in HHH-syndrome, and further important pathophysiologic indicators of cellular and metabolic function have been conscientiously investigated and compared. The pathophysiological repercussions of our results as well as the recommendations for conscientious therapeutical management are discussed.

Adult↗
PubMed2001

Effects of diazepam on neutrophil (PMN) free amino acid profiles and immune functions in vitro. Metabolical and immunological consequences of L-alanyl-L-glutamine supplementation.

The objective of this study was to determine the effects of diazepam, L-alanyl-L-glutamine (ala-gln) or diazepam combined with ala-gln on polymorphonuclear leukocyte (PMN) free amino acid profiles. In a parallel study the effects on PMN immune functions were also documented for the first time. The incubation of whole blood with diazepam led to significant changes in PMN free glutamine, aspartate, glutamate, ornithine, arginine, citrulline, taurine and methionine as well as branched chain and neutral amino acid concentrations. Ala-gln caused significant increases in PMN glutamine and alanine and asparagine, aspartate, glutamate, ornithine, arginine, serine and glycine profiles. Regarding PMN immune functions, diazepam significantly decreased superoxide anion (O(2)(-)) and hydrogen peroxide production (H(2)O(2)) and myeloperoxidase activity (MPO) while ala-gln significantly increased PMN immune functions. Ala-gln supplemented to diazepam largely reversed the changes in PMN amino acid profiles and PMN immune functions brought about by diazepam. Overall, diazepam or ala-gln lead to significant changes in PMN free amino acids. Important PMN immune functions also seem to be affected. In regards to the results, there is significant relevance to the pharmacological regimens which enhance the supply of diazepam or ala-gln in whole blood suggesting that considerable changes in PMN "labile free amino acid pool" occur. These regimens often follow beneficial nutritional therapy or maleficent pharmacological stress and may be one of the determinants in cell nutrition which influence PMN function. It is partially through its effect on PMN labile free amino acid pool that ala-gln supplemented to diazepam may maintain PMN immune functions in vitro.

Journal Article↗
PubMed2001

Boundary element method volume conductor models for EEG source reconstruction.

OBJECTIVES: The boundary element method (BEM) approximates the different compartments of volume conductor models by closed triangle meshes with a limited number of nodes. The shielding effect of the weakly conducting skull layer of the human head leads to decreasing potential gradients from the inside to the outside. Thus, there may be an optimum distribution of nodes to the compartments for a given number of nodes corresponding to a fixed computational effort, resulting in improved accuracy as compared to standard uniform distributions. METHODS: Spherical and realistically shaped surfaces are approximated by 500, 1000, 2000, and 3000 nodes, each leading to BEM models with 1500-9000 nodes in total. Electrodes are placed on extended 10/20-system positions. Potential distributions of test-dipoles at 4000 random positions within the innermost compartment are calculated. Dipoles are then fitted using 192 different models to find the optimum node distribution. RESULTS: Fitted dipole positions for all BEM models are evaluated to show the dependency of the averaged and maximum localization errors on their node distributions. Dipoles close to the innermost boundary exhibit the largest localization errors, which mainly depend on the refinement of this compartment's triangle mesh. CONCLUSIONS: More than 500 nodes per compartment are needed for reliable BEM models. For a state-of-the-art model consisting of 6000 nodes overall, the best model consists of 3000, 2000, and 1000 nodes from the inside to the outside.

Brain↗
PubMed2001

Spatio-temporal current density reconstruction (stCDR) from EEG/MEG-data.

Among the different approaches to the bioelectromagnetic inverse problem, the current-density reconstruction methods (CDR) provide the most general solutions. Since the inverse problem does not have a unique solution, model assumptions have to be taken into account. Multi-channel measurements contain not only spatial, but also temporal information about the sources, so a naturally extension to existing methods leads to spatio-temporal model constraints. Spatio-temporal CDR's (stCDR) have been tested in simplified volume conductor models, assuming different spatial model constraints and a smooth temporal activation model. Comparison to existing spatial model constraints showed a significant improvement of spatial and temporal resolution of the reconstructed sources for the spatio-temporal models especial in noisy data.

Algorithms↗
PubMed2001

Methohexital affects neutrophil (PMN) dynamic free amino acid pool and immune functions in vitro.

BACKGROUND AND OBJECTIVE: The objective of this study was to determine the dose as well as the duration of exposure-dependent effects of methohexital on neutrophil [polymorphonuclear leucocyte (PMN)] free amino acid profiles and, in a parallel study, on PMN immune functions. METHODS: Whole blood samples were taken from 20 volunteers and incubated with methohexital [0 (control), 3.6, 26, 130 and 260 microg mL-1] for 10, 30, 60 or 120 min. PMN amino acid profiles were documented using advanced PMN separation and high-performance liquid chromatography procedures. Superoxide anion (O2-) and hydrogen peroxide production (H2O2), and activity of released myeloperoxidase (MPO), were determined photometrically. RESULTS: After methohexital, significant dose (> or = 26 microg mL-1) as well as duration of exposure-dependent (> or = 30 min) increases in histidine, isoleucine, leucine, valine, methionine, serine, glycine, threonine, and decreases in glutamine, glutamate, aspartate, asparagine, arginine, ornithine, citrulline, alanine and taurine were observed (P < or = 0.05). Concerning PMN immune functions, methohexital significantly decreased O2-, H2O2 formation and MPO (> or = 26 microg mL-1, > or = 30 min, P < or = 0.05). CONCLUSIONS: Altogether, there is significant relevance to the pharmacological regimens which enhance the supply of methohexital in whole blood. In regards to our results, we suggest that considerable changes in PMN 'dynamic free amino acid pool', for example induced by methohexital, may be one of the determinants in cell nutrition adversely affecting PMN metabolism. It is partially through its effect on the PMN free amino acid pool that maleficent pharmacological stress may have an unintentional influence on PMN immune functions.

Adult↗
PubMed2001

Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask.

Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.

Adult↗
PubMed2001

Biliary cholesterol hypersecretion in gallstone-susceptible mice is associated with hepatic up-regulation of the high-density lipoprotein receptor SRBI.

Enhanced hepatocellular trafficking of cholesterol to the bile canaliculus and cholesterol hypersecretion appears critical for gallstone formation. Therefore, we studied in more detail the hepatic cholesterol transport pathways in a mouse model of cholesterol gallstone disease. Biliary lipid secretion rates, plasma lipoprotein levels, hepatic expression of lipoprotein receptors, lipid regulatory enzymes, and putative cholesterol transporting proteins were analyzed in gallstone-susceptible C57L/J and gallstone-resistant AKR/J mice, which were fed a lithogenic diet. Biliary cholesterol hypersecretion in C57L mice was associated with decreased plasma high-density lipoprotein (HDL) cholesterol levels and significant hepatic induction of the HDL receptor (SRBI) and cholesteryl ester hydrolase. In response to the lithogenic diet, fatty-acid binding protein of liver (FABPL) was markedly induced in both mouse strains. Caveolin 1 was elevated only in plasma membranes of gallstone-susceptible C57L mice, which also failed to down-regulate cholesterol synthesis. These data suggest a role of the reverse cholesterol transport pathway for genetically determined gallstone susceptibility in the mouse.

Animals↗
PubMed2001

[Telemedicine in phoniatrics and pediatric audiology--possible applications, technical implementation, economic aspects].

BACKGROUND: Phoniatrics and Paedaudiology investigate and treat disorders of communication more than other medical specialties and are indicated by a distinctive interdisciplinary character. The methods of diagnosis and therapy are concentrated on a few specialists and produce a large quantity of multi-media data from daily clinical practice and research. For the cooperation between the specialists of these and neighboring branches and to reduce the costs for a second opinion these data must be available anywhere and any time using modern telecommunication and information technologies. METHODS: Following applications for a bi- or multidirectional data transmission are possible: Teleconsulting (second opinion of a far located specialist). Teleteaching (use of different data sources for education) and Teleroboting (remote control of medical equipment). Data sources can be: speaking and singing voice, sound, pictures (X-ray, CT, MR, ultrasound, voice range profile, audiogramm), video signals (stroboscopy, cinematography, intraoperative pictures) and written information (computer presentations) in all combinations. The transmission can be carried out synchronously or asynchronously, i.e. at the time for their generation or independent of this. This paper discusses the basics and the advantages and disadvantages of the available technologies and compares it for phoniatric/paedaudiologic applications in an experimental transmission. RESULTS: Use of the different technologies should be carried out depending upon the required quality, the availability and the costs considering medico-legal aspects. Relatively cheap and always available technologies are suitable for many applications in Phoniatrics and Paedaudiology. High costs for acquisition of the equipments could lowered by a common use of different medical branches. Expensive procedures with excellent communication quality are confined to special applications at the moment. CONCLUSION: Telemedicine can optimize quality and extend of the medical care and education in Phoniatrics and Paedaudiology with a simultaneous cost reduction and should increasingly be used in this branch.

Child↗
PubMed2001

[Kickboards - Cause of injury, patterns of injury and prevention].

69 patients with kickboard injuries were treated over a 5-month period. 6 patients were admitted to hospital. Fractures (48%), contusions/ lacerations (45%) and capsular/ ligamentuous injuries (27%) were the most prevalent types of injury. Injuries of the elbow, forearm, wrist and hand accounted for 54% of all cases. Ankle (23%), head (6%) and knee were other regions frequently involved. It is concluded that kickboard-driving imposes a severe risk of injuries. The typical kickboard injuries was the fracture of the wrist and the ankle sprain. Protective equipment for the injured regions is very important to prevant injury.

Adolescent↗
PubMed2001

Indirect evidence that intestinal bile salt absorption in rats and hamsters is under positive feedback control.

Bile salts are reabsorbed from the intestine by active and passive transport mechanisms with great efficacy. Conflicting data do not allow to judge for certainty whether bile salt absorption is under negative or positive feedback control. To address this issue, we analyzed bile salt absorption in vivo along the entire intestinal tract of rats and hamsters that received intraduodenal bile salt infusions for 54 h following interruption of the enterohepatic circulation. Taurocholate absorption in rats was complete, even when unphysiologically high concentrations of taurocholate were given. The combined infusion of taurocholate together with potent inhibitors of bile salt synthesis such as deoxycholate, taurodeoxycholate or taurochenodeoxycholate, failed to inhibit bile salt absorption. In the hamster, taurochenodeoxycholate and taurocholate absorption was complete and could not be inhibited when given in supraphysiological concentrations. Finally, taurocholate absorption was not impaired when deoxycholic acid was infused. These results provide indirect evidence that bile salt absorption is under positive feedback control regulated by luminal bile salt concentrations.

Animals↗
PubMed2001

Numerical aspects of spatio-temporal current density reconstruction from EEG-/MEG-data.

The determination of the sources of electric activity inside the brain from electric and magnetic measurements on the surface of the head is known to be an ill-posed problem. In this paper, a new algorithm which takes temporal a priori information modeled by the smooth activation model into account is described and compared with existing algorithms such as Tikhonov-Phillips.

Algorithms↗
PubMed2000

Higher-order glass-transition singularities in colloidal systems with attractive interactions.

The transition from a liquid to a glass in colloidal suspensions of particles interacting through a hard core plus an attractive square-well potential is studied within the mode-coupling-theory framework. When the width of the attractive potential is much shorter than the hard-core diameter, a reentrant behavior of the liquid-glass line and a glass-glass-transition line are found in the temperature-density plane of the model. For small well-width values, the glass-glass-transition line terminates in a third-order bifurcation point, i.e., in a A3 (cusp) singularity. On increasing the square-well width, the glass-glass line disappears, giving rise to a fourth-order A4 (swallow-tail) singularity at a critical well width. Close to the A3 and A4 singularities the decay of the density correlators shows stretching of huge dynamical windows, in particular logarithmic time dependence.

Journal Article↗
PubMed2000

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana.

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Arabidopsis↗
PubMed2000

[Pericardial tamponade during installation of a central venous catheter].

A case report demonstrates the complication of pericardial tamponade during the installation of a central venous catheter via the subclavian vein. To reduce the high mortality of this rare complication, quickly applicable diagnostic measures and adequate therapy of pericardiocentesis are indicated. Prompt recognition and treatment of pericardial tamponade are imperative if a disastrous outcome is to be prevented.

Adolescent↗
PubMed2000

[Similarity of monozygotic twins regarding vocal performance and acoustic markers and possible clinical significance].

Auditory similarities in voices of monozygotic twins have already been described in the literature. However, is there a clinical relevance? Thus, the present study was designed to identify parameters of vocal performance and acoustic features which are significantly more similar in monozygotic twins than in non-related persons. In our hypothesis, comparable prerequisites for an increased vocal load in a profession or in an artistic education of the voice could be due to these similarities. We compared intra-pair differences with data from a control group. Moreover, we examined the correlation of intra-pair differences with the age of the monozygotic twins. A greater difference in older twin pairs than in younger pairs could show the effect of an exogene influence. In addition to the few phoniatric studies in twins in the literature, we used current methods for acoustic analysis. We examined seven parameters of vocal performance and three acoustic features in 31 monozygotic twin pairs (median age 36 years, range 18-75 years) and compared them with 30 control group pairs, which consisted of non-related persons of the same age and sex, newly combined from the group of monozygotic twins ("statistical twins"). We found significant differences in seven of ten parameters (vocal range, highest and lowest vocal fundamental frequency, fundamental speaking frequency, maximum voice intensity, number of partials, vibrato of intensity; U-test by Mann-Whitney). No correlation of the differences of the identical twins with age was found in the examined parameters. The voices of identical twins are significantly more similar than those of non-related persons regarding the above mentioned features. Thus, the suitability of the voices of monozygotic twins for professions with a high demand on voice is comparable. Results of the group comparison correlate largely with the literature. The missing correlation with age could be due to the fact that the environmental effects were not measurable, and/or the development of the voice is more influenced by genetic effects.

Adolescent↗