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Biomedical subjects

B Fischer

Publications and source records attributed to B Fischer.

At least 199 records · Page 11Linked to original sources
PubMed1995

Influence of age, treadmill running, and food restriction on plasma fibrinogen concentration and expression of gamma chain mRNA in female Sprague-Dawley rats.

Plasma fibrinogen concentration and expression of mRNA encoding the gamma-chain of fibrinogen were determined in female Sprague-Dawley rats aged 10, 21 and 30 months. Both parameters increased significantly with age in a parallel fashion. Food restriction was able to reduce the age-dependent increase of both plasma concentration and gene expression to levels below young controls. On the other hand, long-term treadmill running failed to influence the plasma fibrinogen concentration. From these results we conclude that the plasma fibrinogen concentration increases with age due to an increased fibrinogen biosynthesis.

Aging↗
PubMed1995

[Practical experience of specific catheter ablation of atrial flutter in 110 patients].

The object of this study was to assess the efficacy and risks of radiofrequency ablation of common atrial flutter and to determine the optimal site of ablation in a large population of patients. Three different methods were used to determine the site of ablation: the first was anatomical and electrophysiological whilst the two others were based essentially on anatomical landmarks for localising the critical zone of the reentry circuit. Recent studies report that radiofrequency ablation is effective in interrupting and preventing recurrences of common atrial flutter both by using anatomical and electrophysiological methods. Nevertheless, a larger series of patients was necessary to establish the efficacy and to determine the optimal site of ablation. A series of 110 consecutive patients with common atrial flutter resistant to antiarrhythmic drugs was studied. The site of ablation of the first 50 patients was determined using both anatomical landmarks and electrophysiological parameters. The anatomical zones were: zone 1, between the septal leaflet of the tricuspid valve and the orifice of the inferior vena cava; zone 2, between the septal leaflet of the tricuspid valve and the ostium of the coronary sinus, and zone 3: between the orifice of the inferior vena cava and the ostium of the coronary sinus. The electrophysiological criterion was an endocavitary auriculogramme occurring during the plateau phase preceding the F wave of the flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

[Clinical late manifestation of Ondine's syndrome with pronounced primary, especially sleep related alveolar hypoventilation].

We report on a very rare case of a primary, alveolar hypoventilation syndrome (Ondine's Curse syndrome) in a female patient who was first treated at the age of 26 years as a result of an influenza infection; however, the case history revealed a decreased performance in comparison to similar aged children from earliest childhood onwards as well as an intermittent zyanosis of the lips and distal extremities. Other diseases which could explain a global respiratory insufficiency and/or pulmonary arterial hypertension were excluded.

Adult↗
PubMed1995

[Experimental determination of equivalent percentage changes in measurement parameters of dose-response relations with the inhaled methacholine provocation test].

For the experimental determination of equivalent changes of the measurement parameters in the non-specific inhalative provocation test with metacholine, 26 persons with exogenous allergic asthma bronchiale were examined during the symptom-free interval. The inhalative provocation test was performed as dose-response relationship. Linear regressions were calculated with the data obtained. The percentage change of the measurement parameters that occurred with a quantity of 400 micrograms of aerosolised methacholine was calculated on the basis of the regression equation. These changes correspond to equivalent changes of the individual measurement parameters compared with each other. Generally, a drop in FEV1 by 20% is demanded for a positive provocation test. If this value is defined as "gold standard", the measured data allow derivation of the equivalent changes. Our studies showed that an increase of Rt by 195% (triplication), a sGaw drop by 44%, a PEF drop by 20% and a drop of MEF75, MEF50 by 30% each, compared with the original value, is equivalent to a significant change in the sense of a positive inhalative provocation test.

Adolescent↗
PubMed1995

[Equivalence of methacholine and carbachol in a nonspecific provocation test (dose-response relationship)].

Within the framework of unspecific inhalation provocation tests with pharmacological substances for the purpose of diagnosing bronchial hyperreactivity, the cholinergics methacholine and carbachol are often used besides histamine. We examined 21 patients with known bronchial hyperreactivity in the symptom-free interval using the methacholine inhalation provocation test and 15 hyperreactive patients using the carbachol inhalation provocation test with the purpose of determining the extent to which methacholine and carbachol differ from each other in respect of their effect. Standard reference values were the provocation doses PD100/0.5Rt and PD20FEV1. It was found that methacholine and carbachol exercise an equivalent effect in the inhalation provocation test. No statistically significant difference for the provocation doses PD100/0.5Rt and PD20FEB1 was seen in group comparisons.

Adolescent↗
PubMed1995

[61-year-old patient with rapidly progressive cerebellar symptoms].

The rare case of a paraneoplastic, cerebellar degeneration is reported. In addition to the valuable early diagnosis of tumor disease, this paraneoplastic occurrence can also lead to false diagnoses in regard to both the underlying disease and the staging of the tumor. In the cases of known tumor disease, the assumption of cerebral metastasis is also possible.

Autoantibodies↗
PubMed1995

Modelling the P2Y purinoceptor using rhodopsin as template.

The P2Y1 purinoceptor cloned from chick brain (Webb, T. et al (1993) FEBS Lett., 324, 219-225) is a 362 amino acid, 41 kDa protein. To locate residues tentatively involved in ligand recognition a molecular model of the P2Y purinoceptor has been constructed. The model was based on the primary sequence and structural homology with the G-protein coupled photoreceptor rhodopsin, in analogy to the method proposed by Ballesteros and Weinstein ((1995) Meth. Neurosci. 25, 366-428). Transmembrane helices were constructed from the amino acid sequence, minimized individually, and positioned in a helical bundle. The helical bundle was then minimized using the Amber forcefield in Discover (BIOSYM Technologies) to obtain the final model. Several residues that have been shown to be critical in ligand binding in other GPCRs are conserved in the P2Y1 purinoceptor. According to our model the side chains of these conserved residues are facing the internal cleft in which ligand binding likely occurs. The model also suggests four basic residues (H121 in TM3, H266 and K269 in TM6 and R299 in TM7) near the extracellular surface that might be involved in ligand binding. These basic residues might be essential in coordinating the triphosphate chain of the endogenous ligand adenosine 5'-triphosphate (ATP). Potential binding sites for agonists have been explored by docking several derivatives (including newly synthesized N6-derivatives) into the model. The N6-phenylethyl substituent is tolerated pharmacologically, and in our model this substituent occupies a region predominantly defined by aromatic residues such as F51 (TM1), Y100 (TM2) and F120 (TM3). The dimethylated analogue of ATP, N6,N6-dimethyl-adenosine 5'-triphosphate, is less well tolerated pharmacologically, and our model predicts that the attenuated activity is due to interference with hydrogen bonding capacity to Q296 (TM7).

Amino Acid Sequence↗
PubMed1995

Drugs, communities, and "harm reduction" in Germany: the new relevance of "public health" principles in local responses.

Drug policy in Germany currently is subject to dramatic changes away from the dominance of repression and hard-line prohibition. However, a crucial share of the recent initiatives (decriminalization, "low threshold" social services, needle exchanges, opiate substitution programs etc.) that define the new interaction between the public system and the drug user have not occurred through any decisive changes in the main state-policy instruments. A possible legal shift was, for example, explicitly denied in the recent decision of the German Constitutional Court on the constitutionality of the German narcotics control law. Rather, these moves are the result of pragmatic, cooperative action at the front-line of communities directly confronted with drug use and the resulting problems. This paper looks in embracing progressive, "harm reduction"-based approaches for their communities' drug problem despite predominant indifference or resistance from other political levels. An overview is given of how the different actors involved in implementing front-line drug policy--police, social services, health agencies--have changed their approach in order to pragmatically "reduce harm" to drug users and their communities. As assessment of the effects of this substantial shift in public action towards drugs is suggested through changes in indicators of drug-related harm, e.g., the prevalence of drug-related deaths, health problems, provision of social services, effects of substitution programs, and drug-related crime rates.

Community Participation↗
PubMed1994

Structural analysis of recombinant von Willebrand factor: identification of hetero- and homo-dimers.

Wild-type full-length cDNA of von Willebrand factor (vWF) was expressed in CHO cells. Recombinant vWF (rvWF) was obtained and its molecular composition investigated by two-dimensional electrophoresis. Results of first dimension electrophoresis under non-reducing conditions showed that rvWF-dimer represents a mixture of three different species. Second dimension electrophoresis under reducing conditions revealed, that these protein species represent (i) homo-dimers of either two unprocessed or two fully processed, mature vWF polypeptides, and (ii) the hetero-dimer of unprocessed and mature rvWF monomers. Compared with vWF-dimers from human plasma, which contained predominantly proteolytically degraded polypeptides, recombinant vWF-dimers were shown to consist of non-proteolyzed subunits only.

Animals↗
PubMed1994

Making a small enzyme smaller; removing the conserved loop structure of hen lysozyme.

Engineering a smaller lysozyme is a challenge for both random and site-directed mutagenesis. This paper illustrates the power of knowledge-based protein engineering in the design of a smaller lysozyme that folds correctly and has activity against bacterial cell walls. In this smaller lysozyme the conserved disulphide bridged loop is replaced by a short loop. The long loop was selected because it buries a predominantly hydrophilic surface. The short loop was discovered by searching for appropriate fragments in the protein databank. This approach is important in the design of small enzymes useful to the food industry.

Animals↗
PubMed1994

Structure-activity relationships of N6-benzyladenosine-5'-uronamides as A3-selective adenosine agonists.

Adenosine analogues modified at the 5'-position as uronamides and/or as N6-benzyl derivatives were synthesized. These derivatives were examined for affinity in radioligand binding assays at the newly discovered rat brain A3 adenosine receptor and at rat brain A1 and A2a receptors. 5'-Uronamide substituents favored A3 selectivity in the order N-methyl > N-ethyl approximately unsubstituted carboxamide > N-cyclopropyl. 5'-(N-Methylcarboxamido)-N6-benzyladenosine was 37-56-fold more selective for A3 receptors. Potency at A3 receptors was enhanced upon substitution of the benzyl substituent with nitro and other groups. 5'-N-Methyluronamides and N6-(3-substituted-benzyl)adenosines are optimal for potency and selectivity at A3 receptors. A series of 3-(halobenzyl)-5'-N-ethyluronamide derivatives showed the order of potency at A1 and A2a receptors of I approximately Br > Cl > F. At A3 receptors the 3-F derivative was weaker than the other halo derivatives. 5'-N-Methyl-N6-(3-iodobenzyl)adenosine displayed a Ki value of 1.1 nM at A3 receptors and selectivity versus A1 and A2a receptors of 50-fold. A series of methoxybenzyl derivatives showed that a 4-methoxy group best favored A3 selectivity. A 4-sulfobenzyl derivative was a specific ligand at A3 receptors of moderate potency. An aryl amino derivative was prepared as a probe for radioiodination and receptor cross-linking.

Adenosine↗
PubMed1994

Anal endosonography in healthy subjects and patients with idiopathic fecal incontinence.

PURPOSE: This study investigates the normal ultrasonographic morphology of pelvic floor striated muscle and evaluates whether there are differences between males and females and between healthy subjects and patients with idiopathic fecal incontinence. METHODS: Manometric and ultrasonographic studies of the anal canal were performed in 30 healthy volunteers and in 26 patients with idiopathic fecal incontinence. Verification of ultrasonographic findings was obtained by studying anatomic preparations. RESULTS: Ultrasonography reliably identified the internal and external anal sphincter and frequently visualized neighboring structures. In addition, it detected muscular structures that have not clearly been described previously. However, differences in external sphincter function between males and females and between healthy subjects and incontinent patients were not reflected by alterations in muscle thickness. CONCLUSIONS: Endosonography of the anal canal clearly delineates muscular structures and may even visualize structures that have been previously incompletely defined. However, it remains to be shown that differences in certain muscular functions have a morphologic correlate that can be detected by endosonography.

Adult↗
PubMed1994

Differential effects of non-target stimuli on the occurrence of express saccades in man.

The effect of competing non-target stimuli (distractors) presented together with a target for saccades was investigated with special emphasis on saccadic reaction time. Using the gap task (fixation point offset preceding target onset by 200 msec) high numbers of express saccades were obtained from four human subjects. A single non-target stimulus in the visual hemifield contralateral to the target reduced the number of express saccades. The extend of reduction increased with increasing stimulus size leading to a situation where express saccades were replaced entirely with saccades having a latency mode 30 msec later. Non-target stimuli occurring in the hemifield ipsilateral to the saccade target could also reduce the number of express saccades in favour of fast regular saccades. The effect of ipsilateral non-target stimuli depended mainly on their position in the visual field: ipsilateral non-target stimuli outside the dead zone for express saccades caused only a slight reduction of express saccades. Non-target stimuli invading the dead zone, however, suppressed express saccades almost completely, even though the saccade target appeared well outside the dead zone. The onset of a whole field of bars of one orientation (serving as distractors) simultaneously with the target (consisting of a single bar of another orientation = pop-out condition), suppressed express saccades completely. The same result, however, was obtained with only two distractor bars presented ipsilateral and contralateral within the dead zone for express saccades. Express saccades were present, however, when the whole field of distracting bars was continuously visible throughout the whole trial.

Attention↗
PubMed1994

Binding of epidermal growth factor and transforming growth factor-alpha in mammalian preimplantation embryos.

Preimplantation embryos of the pig (Days 11 to 15), cow (Days 14 to 16), sheep (Day 14) and pony (Day 16) bind epidermal growth factor (EGF) specifically. Binding was not detected in embryos of the rabbit at Day 5 or 6 or the hamster at Day 3. Transforming growth factor-alpha displaced [(125)I] EGF in pig, cow and pony embryos almost as much as unlabeled EGF. The binding affinities of EGF ranged from 12 to 233 pM in pig and cow embryos. The range of species and binding features indicate that the EGF family may play a significant role in mammalian preimplantation development.

Journal Article↗
PubMed1994

Effect of oxygen concentration in the incubator's gas phase on the development of cultured preimplantation rabbit embryos.

Development of rabbit preimplantation embryos cultured under 20, 5 or 1% oxygen was studied. Three-day-old morulae were cultured in a protein-free medium (BSM II supplemented with 5 mg PVP/ml medium) for 24 and 48 h. Embryonic development was evaluated by gross morphology and by incorporation of tritiated thymidine as an indicator of cell proliferation. The lower oxygen concentrations yielded significantly better embryo development at 24 and at 48 h than the 20% concentration. There was no significant difference in development between 5% and 1% oxygen. Addition of the radical scavanger superoxiddismutase (SOD), either alone or in combination with catalase or reduced glutathione, did not improve embryo development even in the 20% oxygen group. Our data suggest the need to reduce in vitro oxygen levels from 20% to more physiological concentrations.

Journal Article↗
PubMed1994

Immunologically active polysaccharide from Cetraria islandica.

A new alkali-soluble polysaccharide has been isolated from Iceland moss, Cetraria islandica (L.) Ach., by ethanol fractionation, ion-exchange chromatography, and gel filtration. The mean M(r) was estimated to be 18,000. Sugar and methylation analysis, partial hydrolysis, and 13C-NMR spectroscopy showed the polysaccharide to be a branched galactomannan with a backbone composed of two structural elements; (1-->6)-linked alpha-D-mannopyranosyl and alpha-D-(1-->6)-galactopyranosyl units. The polysaccharide showed pronounced immunostimulating activity in an in vitro phagocytosis assay and in the in in vivo carbon clearance assay.

Carbohydrate Sequence↗