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Biomedical subjects

R Müller

Publications and source records attributed to R Müller.

At least 433 records · Page 24Linked to original sources
PubMed1992

Left ventricular filling behaviour in ultra endurance and amateur athletes: a stress Doppler-echo study.

To evaluate the impact of different training levels on left ventricular (LV) filling dynamics, Doppler mitral flow was derived in 25 amateur endurance-trained athletes (amateurs) aged 31 +/- 9 years, with a personal marathon record > 200 min, and in 26 ultra endurance athletes (top athletes) aged 32 +/- 8 years, with a personal marathon record < 170 min, during bicycle exercise in supine position. In particular atrial filling fraction as the relative share of atrial contribution to LV filling was measured. During exercise (150 watt) atrial filling fraction increased significantly more in amateurs from 25% to 34% compared to top athletes from 25% to 29% (p < 0.001). Two min post exercise atrial filling fraction already reached baseline values in top athletes (25%), while it remained significantly elevated in amateurs compared to baseline values (29%, p < 0.001). Only ten min post exercise atrial filling fraction showed baseline values in amateurs (26%). Rate pressure product was not significantly different at all levels of exercise. Thus, while atrial filling fraction rose in both study groups during exercise, it returned earlier to baseline values in top athletes than in amateurs. This indicates a better cardiac adaptation to physical stress and a better diastolic performance during exercise in endurance athletes with a higher training level.

Adaptation, Physiological↗
PubMed1992

Purification and some properties of 2-halobenzoate 1,2-dioxygenase, a two-component enzyme system from Pseudomonas cepacia 2CBS.

The two components of the inducible 2-halobenzoate 1,2-dioxygenase from Pseudomonas cepacia 2CBS were purified to homogeneity. Yellow component B is a monomer (Mr, 37,500) with NADH-acceptor reductase activity. Ferricyanide, 2,6-dichlorophenol indophenol, and cytochrome c acted as electron acceptors. Component B was identified as an iron-sulfur flavoprotein containing 0.8 mol of flavin adenine dinucleotide, 1.7 mol of iron, and 1.7 mol of acid-labile sulfide per mol of enzyme. The isoelectric point was estimated to be pH 4.2. Component B was reduced by the addition of NADH. Red-brown component A (Mr, 200,000 to 220,000) is an iron-sulfur protein containing 5.8 mol of iron and 6.0 mol of acid-labile sulfide. The isoelectric point was within the range of pH 4.5 to 5.3. Component A could be reduced by dithionite or by NADH plus catalytic amounts of component B. Component A consisted of nonidentical subunits alpha (Mr, 52,000) and beta (Mr, 20,000). It contained approximately equimolar amounts of alpha and beta, and cross-linking studies suggested an alpha 3 beta 3 subunit structure of component A. The NADH- and Fe(2+)-dependent enzyme system was named 2-halobenzoate 1,2-dioxygenase, because it catalyzes the conversion of 2-fluoro-, 2-bromo-, 2-chloro-, and 2-iodobenzoate to catechol. 2-Halobenzoate 1,2-dioxygenase exhibited a very broad substrate specificity, but benzoate analogs with electron-withdrawing substituents at the ortho position were transformed preferentially.

Amino Acid Sequence↗
PubMed1992

Mouse apolipoprotein AI. cDNA-derived primary structure, gene organisation and complete nucleotide sequence.

Apolipoprotein AI, the dominant protein component of serum high density lipoprotein, is intimately involved in cholesterol homeostasis. Apo AI activates the lecithin-cholesterol acyltransferase within the HDL particle and functions as ligand for a putative HDL receptor--two properties, which render this apolipoprotein a key mediator in reversed cholesterol transport. A functional analysis of the apo AI gene demands the isolation of the mouse apo AI gene for expression as transgenes in different mutant forms in the mouse. Here we describe the isolation of a full length apo AI-specific mouse liver cDNA clone with the human cDNA (892 bp) and the derived amino-acid sequence coding a polypeptide of 264 amino-acid residues. It showed a 70.7% homology to the rat and 66% to the human apo AI sequence. With this cDNA as probe the mouse apo AI gene was isolated and its organization analysed. Four exons, three of which are coding sequences, are aligned similarly to the human gene. The gene embraces 1825 bp between the transcription start, and the poly(A)+ tail attached 62 bp downstream of the stop codon. The complete nucleotide sequence of the four exons and three introns of the mouse apo AI gene was determined and its homology compared with that of the rat and human gene. Extensive deletions and a strongly reduced homology of the three introns of the two genes are obvious.

Amino Acid Sequence↗
PubMed1992

Purification and properties of 4-halobenzoate-coenzyme A ligase from Pseudomonas sp. CBS3.

The bacterial strain Pseudomonas sp. CBS3 possesses a multi component enzyme system which converts 4-chlorobenzoate to 4-hydroxybenzoate. In the first step 4-chlorobenzoate is activated in a coenzyme A, ATP and Mg(2+)-dependent reaction to 4-chlorobenzoyl-coenzyme A. ATP is cleaved thereby into AMP and pyrophosphate. The involved 4-chlorobenzoate-coenzyme A ligase was purified to apparent homogeneity by a 6-step purification procedure. The native enzyme had an apparent molecular mass of 115000 Da and was composed of two identical polypeptide subunits of 57 kDa. The enzyme displayed an isoelectric point of 5.3. The maximal initial rate of catalysis was achieved in 100mM Tris/HCl or Tricine/NaOH buffer, pH 8.4, at 35 degrees C. Under these conditions the apparent Km values for ATP, coenzyme A and 4-chlorobenzoate were 2.4 to 3.5 mM, 0.11 to 0.19mM and 0.05 to 0.065mM, respectively. Vmax was 111.6 mumol/(min x mg protein). The N-terminal amino-acid sequence was determined. 4-Halobenzoates were preferentially converted to the corresponding thioesters. Therefore, the enzyme was named 4-halobenzoate-coenzyme A ligase.

Adenosine Triphosphate↗
PubMed1992

Analysis of temperature-sensitive functions of Fos: lack of a correlation between transformation and TRE-dependent trans-activation.

We have identified and characterized a mutant v-Fos protein (DN16G) that is temperature sensitive for transformation. This protein contains an asparagine to glycine substitution at position 156 in the basic region encompassing the DNA contact site. This point mutation also strongly decreases trans-activation in a transient expression assay, using the collagenase 12-O-tetradecanoyl phorbol 13-acetate (TPA)-responsive element (TRE) as the target element. However, the apparent correlation between trans-activation and transformation does not hold in view of the observation that under certain temperature conditions (DN16G at 39.5 degrees C and E300 at 37 degrees C) both proteins showed similarly poor transactivation properties, but dramatically differed in their transforming potential. These findings clearly suggest that the activation of transcription via TREs as analysed in this study is not a crucial mechanism in Fos-induced transformation.

Cell Transformation, Neoplastic↗
PubMed1992

[Effects of endurance training on left ventricular filling dynamics: a study using stress Doppler echocardiography].

To evaluate the impact of endurance training on left-ventricular (LV) filling dynamics Doppler mitral flow was derived in 23 amateur endurance-trained athletes (AT) aged 31 (24-39) years with a personal marathon record greater than or equal to 200 min, and in 20 ultra-endurance athletes (UEA) aged 38 (28-42) years with a personal marathon record less than 200 min during bicycle exercise in supine position. Twenty-two untrained healthy volunteers (UT) aged 27 (24-30) years served as control. In particular, atrial filling fraction (AFF) as the relative share of atrial contribution to LV filling was measured. At rest AFF was significantly higher in UT (29%) as compared to AT (25%) and UEA (25%). During exercise (150 watt) atrial fraction increased significantly more in UT (37%) as compared to AT (34%) and UEA (29%) (p less than 0.01). At this point of measurement UEA had significantly lower values for AFF than AT (p less than 0.001). Two min post exercise atrial filling fraction already reached baseline values in UEA (24%) and AT (26%), while it remained significantly elevated in UT as compared to baseline values (38%, p less than 0.001). Ten min post exercise atrial filling fraction showed still elevated values in UT (32%), but decreased under baseline values in UEA (23%). No differences in heart rate between the two athlete groups at all times of measurement were observed. Thus, while atrial filling fraction rose in all study groups during exercise, it returned earlier to baseline values in athletes than in untrained subjects. This indicates a better cardiac adaptation to physical stress and a better diastolic performance during exercise in endurance-trained athletes, being even more pronounced in ultra-endurance athletes.

Adult↗
PubMed1992

[The effect of biomaterials and other industrial materials on the growth of several aerobic bacterial species in vitro].

The article deals with interactions between bio-vitro-materials and bacteria species in vitro. The growth of S. aureus, Sc. salivarius, E. coli and Ps. aeruginosa in a salt solution with and without addition of biomaterials was examined until the day 60 in a static culture. By counting the cfu/ml and determination the relative change of germ capacity the results were compared. The data of such series obtained with working materials of similar chemical composition were collected and evaluated. We found, that Ps. aeruginosa was promoted in growth by all materials, especially those, which contained carbon. The same can be said about the last materials and E. coli. In contrast as well Ca- and P-containing as--free biomaterials reduced the numbers of germs. Changes of multiplying of S. aureus and Sc. salivarius seldom were observed. It ist apparent, that the biomaterials tested are not indifferent against a few germs, which may cause infections, but they promote the growth of a few species in vitro. This may favour an infection, if such materials should be implanted. It is proposed to test biomaterials microbiologically before clinical application. Materials with indifferent behavior or low anti-microbiological effect have to be favoured.

Bacteria, Aerobic↗
PubMed1992

Inhibition of Fos- and Ras-induced transformation by mutant Fos proteins with structural alterations in functionally different domains.

We show that transformation-defective Fos proteins lacking either a functional leucine zipper (mutants L345 and J/R510s) or the 110 amino-terminal amino acids (mutant BR800) inhibit the induction of morphological transformation by v-Fos. Both types of mutants specifically repress transformation without any significant effect on cell proliferation. In contrast, several transformation-defective Fos mutants with structural alterations in the acidic region or the right half of the adjacent basic DNA contact site do not show any inhibition of transformation. This result, taken together with the repression of transformation by the leucine zipper-deficient mutants L345 and J/R510s, indicates that the interaction of Fos with proteins other than Jun is necessary for transformation. The leucine zipper-deficient mutants also inhibit Fos-mediated activation of AP-1-dependent transcription. This suggests that their inhibitory effect on transformation may at least in part be the result of the squelching of proteins other than Jun family members that are required for Fos-mediated transactivation. All three mutants were also found to inhibit transformation by the point-mutated H-ras oncogene from EJ carcinoma cells and to trigger a partial reversion of the transformed phenotype of Ras-transformed fibroblasts. These findings support the conclusion that Ras-induced transformation involves signal transduction pathways inducing the c-fos gene.

Cell Division↗
PubMed1992

Increase of survival time in experimental hypoxia by cytidine diphosphate choline.

36 Wistar rats were kept in chronic hypoxic hypoxia of 7 vol % of oxygen in 2 experiments over a period of 6 months, other 36 served as controls. Half of the animals of each group received cytidine diphosphate choline (CDP-choline, citicoline, Somazina; CAS 987-78-0) at a dose of 100 mg/kg body weight in the liquid food. Animals in chronic hypoxia without application of CDP-choline developed pathological symptoms and began to die after 19 to 23 weeks in hypoxia. Rats that received CDP-choline developed less prominent pathological symptoms and died later or remained alive until the end of the experiment. Under conditions of extreme hypoxia CDP-choline exhibited a life-prolonging effect.

Animals↗
PubMed1991

[Disordered alpha 2-adrenoreceptor function in hemodialysis patients with renal anemia--a possible cause of increased blood pressure in relation to recombinant human erythropoietin?].

Nine patients on maintenance hemodialysis and transfusion-demanding renal anemia (group A) were treated with rHuEPO 120 IU/kg i.v. three times per week. Hemoglobin-content was raised from 7.2 +/- 0.9 to 10.4 +/- 0.8 g/dl. In all patients blood pressure rose, three patients developed arterial hypertension. Mean diastoloic blood pressure was 66 +/- 12 and 78 +/- 16 mmHg (p less than 0.001) before and after rHuEPO. Rise in blood pressure was accompanied by a significant fall in plasma-noradrenaline-levels (from 498 +/- 100 to 383 +/- 75 pg/ml; p less than 0.05) and alpha 2-adrenoceptor-density (from 574 +/- 76 to 384 +/- 49; p less than 0.05). Compared to nine patients on maintenance hemodialysis and hematocrit over 30% (group B), patients with severe renal anemia (group A before treatment) had higher densities of alpha 2-adrenoceptors (574 +/- 76 vs. 218 +/- 32; p less than 0.001) despite higher plasma-noradrenaline-levels (498 +/- 100 vs. 399 +/- 63; n.s.). We suppose a anemia-related disturbance of alpha 2-receptor-function with the result of abolished receptor down-regulation and impaired vascular reagibility to vasoconstricting stimuli. With the correction of anemia receptor-function improves, receptor down-regulation as well as vascular reagibility is re-established resulting in augmented vascular resistance and higher blood pressure.

Adult↗
PubMed1991

Identification of 4-chlorobenzoyl-coenzyme A as intermediate in the dehalogenation catalyzed by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3.

The intermediate in the reaction catalyzed by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 was identified as 4-chlorobenzoyl-CoA. One component of 4-chlorobenzoate dehalogenase worked as a a 4-chlorobenzoyl-CoA ligase catalyzing the formation of 4-chlorobenzoyl-CoA from 4-chlorobenzoate, coenzyme A and ATP. This intermediate was detected spectrophotometrically and by HPLC. 4-chlorobenzoyl-CoA was the substrate for the dehalogenase component, which catalyzed the conversion to 4-hydroxybenzoate with concomitant release of coenzyme A.

Adenosine Triphosphate↗
PubMed1991

[Pleural fibrosis as a side effect of years-long methysergide therapy].

A 58-year-old man was admitted to hospital because of exertional dyspnoea and a cardiac murmur not previously heard. For one year he was known to have left-sided fibrinous pleuritis. For 5 years he had been taking methysergide for cluster headaches. From 1950-1980 he had worked with asbestos-containing insulating material. Erythrocyte sedimentation rate was greatly increased to 117/136 mm and there was an hypochromic anaemia (Hb 10.4 g/dl). The cholestasis enzymes were elevated (gamma-GT 88 U/l; alkaline phosphatase 511 U/l). Computed tomography of the thorax demonstrated left-sided pleural thickening of up to 3 cm. Endocarditis was excluded (sterile blood culture; normal echocardiogram). There was no evidence of an infectious, immunological or malignant cause for the pleural fibrosis. One year after pleurectomy and having discontinued methysergide all biochemical tests were normal.

Biopsy↗
PubMed1991

Bead cellulose derivatives as supports for immobilization and chromatographic purification of proteins.

Characteristic data are presented for Divicell, a macroporous bead cellulose with excellent flow parameters. The preparation of Divicell derivatives and their properties are described with respect to their application as chromatographic supports. The ion exchangers Divicell DEAE and Divicell CM were manufactured in two types with different exclusion limits and an available capacity for proteins of up to 100 mg/ml gel. Divicell Blue is a bead cellulose with covalently bound Cibacron Blue F3G-A and was found to be a very suitable adsorbent for the selective separation and purification of human serum albumin. Activation of Divicell with sodium periodate, epichlorohydrin and 5-norbornene-2,3-dicarboximido carbonochloridate provided activated supports used for immobilization of ligands in organic solvents and in aqueous solutions. Coupling of amines, diamines, amino acids, carbohydrates and proteins is described. The immobilized ligands retained their biological activity as determined by their specific adsorption of proteins. Divicell alkyl derivatives were tested in hydrophobic interaction chromatography with bovine serum albumin as a model. Examples are presented of the application of Divicell derivatives to the purification of biomacromolecules such as immunoglobulins and lectins by affinity chromatography. The results were comparable to those obtained using the corresponding Sepharose-derived absorbents.

Animals↗
PubMed1991

Multiple interdependent regulatory sites in the mouse c-fos promoter determine basal level transcription: cell type-specific effects.

Although the induction of the mouse c-fos promoter by growth factors and specific signal transduction pathways has been analyzed in some detail, the mechanisms involved in the control of basal level transcription remain largely elusive. In this study, we present evidence for the existence of at least 9 different elements, located between the putative TATA box and position -610, that figure in basal level transcription and represent protein binding sites in different cell types. A major regulatory site in F9END, NIH3T3 and HeLa cells is the CRE around position -60. Other sites, including the SRE, a NF1 site around position -165, a novel site downstream of the SRE and three new sites upstream of the SRE play different cell type-specific roles. In addition, we have identified two regions upstream of the SRE, which seem to have cell type-specific negative regulatory effects. We also find that the precise function of several of these sites depends on the presence or absence of other elements, indicating some form of interaction between different regulatory sites. Finally, we present evidence, that the block of c-fos transcription in F9EC cells is due to the lack of transregulatory proteins, which are induced during retinoic acid mediated differentiation.

Animals↗
PubMed1991

Dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from pseudomonas sp. CBS3: an ATP/coenzyme A dependent reaction.

Pseudomonas sp. CBS3 was grown with 4-chlorobenzoate as sole source of carbon and energy. Freshly prepared cell-free extracts converted 4-chlorobenzoate to 4-hydroxybenzoate. After storage for 16 hours at 25 degrees C only about 50% of the initial activity was left. Treatment at 55 degrees C for 10 minutes, dialysis or desalting of the extracts by gel filtration caused a total loss of the activity of the 4-chlorobenzoate dehalogenase. The activity could be restored by the addition of ATP, coenzyme A and Mg2+. If one of these cofactors was missing, no dehalogenating activity was detectable. The amount of 4-hydroxybenzoate formed was proportional to the amount of ATP available in the test system whereas CoA served as a real coenzyme. A novel ATP/coenzyme A dependent reaction mechanism for the dehalogenation of 4-chlorobenzoate by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 is proposed.

Adenosine Triphosphate↗
PubMed1991

[The programming of cardiac pacemakers--wish and reality].

To test the extent and quality of pacemaker programming, 340 programmable pacemakers were selected out of 1,204 impulse generators removed post-mortem. Their actual program was compared with the nominal parameters when first delivered. 177 (52.1%) of the 340 pacemakers still had the same parameters as on delivery. The multiply programmable impulse generators with telemetry were more frequently programmed (61.2%) than the simple programmable ones (43.0%) or the multiply programmable ones without telemetry (43.7%). Rate was the most frequently programmed parameter, followed by impulse amplitude, sensitivity and impulse duration. Refractory time and hysteresis were only rarely changed from the initial state. Apparently, programmability was not thought to be important enough. Programming without telemetry was seemingly too complicated. The reasons for this attitude should be investigated so that the discrepancy between wishes and reality can be overcome.

Equipment Design↗
PubMed1991

[Effect of smoking on relaxation and filling behavior of the left ventricle in healthy probands. An echocardiography study].

UNLABELLED: To examine the impact of acute nicotine consumption echocardiographic examination was performed in 22 healthy subjects (nine women, 13 men, 20 to 50 cigarettes/day over a minimum of five years) without any evidence of organic heart disease (normal 2D and Doppler echo, normal ECG at rest and during exercise) aged 20 to 51 years (mean +/- SD: 37 +/- 9 years) before and after cigarette smoking (0.9 mg nicotine). Left ventricular filling parameters were derived by transmitral pulsed Doppler ultrasound with the flow profile along the mitral valve being characterized by the early diastolic (E-wave) and late diastolic (A-wave) inflow into the left ventricle. The isovolumetric relaxation period was determined by simultaneous M-mode registrations over the aortic and mitral valve. During smoking the early diastolic peak velocity decreased from 56 to 52 cm/s (p less than .01) and the early diastolic flow integral fell from 64 to 56 mm (p less than .01). The A/E ratio of the peak velocities rose from 68 to 82% (p less than .001), the A/E ratio of the flow integrals increased from 46 to 56% (p less than .001) and the atrial contribution to ventricular filling rose from 33 to 36% (p less than .001). Furthermore during cigarette smoking the isovolumetric relaxation period rose from 70 to 77 ms (p less than .001). - CONCLUSION: In healthy subjects cigarette smoking causes an increase of the atrial contribution to ventricular filling and the isovolumetric relaxation period. Thus, acute nicotine consumption significantly impairs the energy-consumpting process of early diastolic relaxation, independently of its role as a risk factor for atherosclerosis.

Adult↗