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Biomedical subjects

B Hauer

Publications and source records attributed to B Hauer.

66 records · Page 4Linked to original sources
PubMed1995

[The T-wave shock: a new reliable method for induction of ventricular fibrillation in ICD testing].

During ICD-implantation it is necessary to induce ventricular fibrillation several times to determine the defibrillation threshold. In third generation ICDs there are several options to induce ventricular fibrillation. We want to present a new method, called T-wave-shock, which is first available in the PCD Jewel 7219 (Medtronic). The T-wave-shock is the delivery of a low-energy-shock into the vulnerable period after ventricular stimulation with a basic cycle-length. We applied the T-wave-shock in 46 consecutive ICD-recipients intraoperatively and at the pre-hospital-discharge test. The method is highly effective when applying the shock into the ascending part of the T-wave (98% of the patients were inducible), and the duration of cardial and cerebral ischemia during induction is short (between 3.1 and 3.8 s). This raises defibrillation efficacy.

Adult↗
PubMed1994

The Tn5 bleomycin resistance gene confers improved survival and growth advantage on Escherichia coli.

The bleomycin resistance gene (ble) of transposon Tn5 is known to decrease the death rate of Escherichia coli during stationary phase. Bleomycin is a DNA-damaging agent and bleomycin resistance is produced by improved DNA repair which also requires the host genes aidC and polA coding, respectively, for an alkylation-inducible gene product and DNA polymerase I. In the absence of the drug, this DNA repair system is believed to cause the slower death rate of bleomycin-resistant bacteria. In this study, the effect of ble and aidC genes on the viability of bacteria and their growth rate in chemostat competitions was studied. The results indicate, that bleomycin-resistant bacteria display greater fitness under these conditions. Another beneficial effect of transposon Tn5 had been previously attributed to the insertion sequence IS 50 R. We were not able to reproduce this result with IS 50 R, however, the complete transposon was beneficial under similar conditions. Moreover, we showed the Tn5 fitness effect to be aidC-dependent. The ble gene was discovered after the fitness effect of IS 50 R had been established; it has not previously been considered to mediate the beneficial effect of Tn5. This possibility is discussed based on the molecular mechanism of bleomycin resistance.

Bleomycin↗
PubMed1991

[Evaluation of thyroid function after myocardial infarction].

The myocardial infarction (M.I.) constitutes an exemplary acute severe affection able to modifie hormonal concentrations. The total and unbound thyroid hormones, reverse T3 (rt3), TSH, and cortisolemia were determined in 24 patients during a period of 21 days in order to compare them to different markers of severity of MI. The initial phase of the disease is characterized by low concentrations of total and free T3 and high concentrations of rT3 combined with more often than not normal total and free T4 and TSH values contrasting with an increase in cortisol levels. The abnormalities were more pronounced the day after admission and then progressively amend. There are several statistic relationship between the marker of severity of MI and thyroid hormones. In the same way total T3 is all the more decreased especially since myoglobin, CPK-MB, ST amplitude and ventricle ejection fraction are more disturbed. Severe forms of MI induces a pseudo central thyroid insufficiency with low T3, low T4 and a tendency to TSH decrease. Total T3 blood levels may usefully contribute to the elaboration of an MI severity index.

Adult↗
PubMed1985

[Beta-blockers in the acute phase of myocardial infarction. Echographic study].

The purpose of this study was to evaluate the ability of beta blocker therapy in decreasing the amount of necrosis during a first transmural myocardial infarction (as evidenced by a local and overall kinetic study using two-dimensional ultrasonography). Twenty patients were randomly placed into 2 groups. Ten patients received 15 mg of metoprolol intravenously followed by 200 mg daily of the drug orally. The results indicated that beta blockers are well tolerated clinically and hemodynamically, and that they significantly reduced the amount of necrosis (p less than 0.05 in anterior myocardial infarctions).

Clinical Trials as Topic↗
PubMed1984

Physical structure, genetic content and expression of the alkBAC operon.

We cloned sequences of the alk (alkane utilization) operon of Pseudomonas and characterized them physically and genetically. These sequences were used to construct a DNA restriction map of the alkBAC region. We physically mapped alk::Tn7 insertions and delta alkBA deletions, and we were able to show complementation or marker rescue of alk point mutations by cloned DNA sequences. Our results confirmed the existence of an operon containing structural loci encoding activities for membrane alkane hydroxylase component (alkB), soluble alkane hydroxylase component (alkA) and membrane alcohol dehydrogenase (alkC). Physical mapping of alkC::Tn7 insertions and complementation of alkC point mutations by cloned sequences from the alkBA region showed that we were previously mistaken in inferring the existence of a separate unlinked alkC cluster. Studies with an alkB-lacZ transcription fusion construct established that the operon is transcribed in the order alkBAC and is under positive regulation by alkR regulatory functions.

Alkanes↗
PubMed1984

Control of Tn7 transposition.

Our isolate of Tn7 (named Tn7S ) contains an IS1 insertion, and this IS1 can be converted into Tn9. In vitro and in vivo deletions of Tn7S and Tn7S ::Tn9 define regions of the transposon required for antibiotic resistance and transposition. Complementation of deletion mutants by cloned Tn7 fragments indicates the existence of two regions, denoted tnp7A and tnp7B , required for all transposition events. Another region, denoted tnp7C , is required for transposition from the chromosome to RP1 but not for transposition from a small IncP-1 replicon to the chromosome. The presence of Tn7S terminal sequences in an RP1 replicon reduces the transposition of a second Tn7S derivative from the chromosome by about one order of magnitude. The measured frequency of Tn7S transpositions from a small IncP-1 replicon to the chromosome depends on the particular incompatibility system used to eliminate that replicon. Genetic and physical data indicate that high frequencies of Tn7S transposition to the chromosome (greater than or equal to 40%) are triggered by the IncP-1 incompatibility reaction, thus suggesting the existence of a Tn7 mechanism for sensing the state of the carrier replicon.

Chromosomes, Bacterial↗
PubMed1984

[Echography in the surveillance of myocardial infarction during the acute phase].

An attempt is made to determine feasibility and capabilities of two-dimensional echocardiography (2DE) during acute myocardial infarction (AMI). Seventy-four consecutive patients with AMI (22 anterior, 29 inferior, 4 lateral, 5 non-transmural) underwent 2DE; in sixty cases, suitable examination was available. Regional wall motion abnormalities were studied by 2 methods, i.e. qualitative in all patients and quantitative in 32 patients. Akinesis or dyskinesis occurred in 57 cases (21/22 in anterior, 4/4 in lateral, 29/29 in inferior, 3/5 in non-transmural AMI) and was observed very early (within the first 24 hours after onset of chest pain). Intraventricular clots were observed in 8 patients (in 7 patients during anterior or lateral AMI) without peripheral embolization. In conclusion, 2DE is a suitable method for evaluation of AMI, especially in early thrombi detection and qualitative wall motion analysis. Evolution of quantitative wall excursion is still under investigation but will be highly attractive, more easily repeatable at the bedside and cheaper than nuclear angiography.

Adult↗
PubMed1982

Papaverine degradation with papaverine mutants of a Nocardia sp.

Nocardia mutants, capable of utilizing papaverine as a sole source of carbon and nitrogen, were induced with N-methyl-N'-nitro-N-nitrosoguanidine and mitomycin C. The isolated mutants were divided in four groups, depending on the accumulated papaverine metabolites: 4 = 2-(2-hydroxy-4,5-dimethoxyphenyl)ethanol; 5 = 3,4-dimethoxyphenylacetic acid; 6 = 2-hydroxy-4,5-dimethoxyphenylacetic acid; 10 = 3-(3,4-dimethoxybenzyl)-2-hydroxy-5,6-dimethoxy-1-indenone; 11 = 4-(3,4-dimethoxybenzyl)-6,7-dimethoxyisocoumarin. The degrading pathway of metabolites 5 and 6 was investigated. Studies of the cell wall and membrane fraction of the mutants and wild-type show two inducible, particle-bound proteins with the molecular mass of 29 000 and 60 000 Da involved in papaverine degradation.

Bacterial Proteins↗
PubMed1982

Tryptophan metabolism by a papaverine-degrading Nocardia sp.

Tryptophan catabolism was studied in a papaverine-degrading Nocardia sp. L-Tryptophan degradation follows the quinoline route via kynurenic acid. 5-(2-Carboxyethyl)-4,6-dihydroxypicolinic acid was isolated as a kynurenic acid metabolite. Mutants were induced with N-methyl-N'-nitro-N-nitrosoguanidine. A mutant was isolated, which accumulated 5-hydroxyanthranilic acid. There is no relationship between kynurenic acid degradation and papaverine degradation. All kynurenic acid mutants were able to use papaverine as a carbon source and all papaverine mutants could be grown at the expense of kynurenic acid.

Kinetics↗