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Biomedical subjects

P Schuster

Publications and source records attributed to P Schuster.

At least 109 records · Page 6Linked to original sources
PubMed1983

[Hemodynamic effects of isosorbide-5-mononitrate in coronary heart disease. A comparison of acute and chronic treatment].

The haemodynamic effect of isosorbide-5-mononitrate (ISMN) was studied in 20 patients with coronary heart disease. Three hours after the first and single dose of 50 mg ISMN, both at rest and on exercise there was a significant decrease in pulmonary artery mean pressure of 30%, while heart rate and systemic blood was an anti-anginal effect, as objectified by the angina threshold and return to normal of previously depressed S-T segments during exercise. After administration of 50 mg ISMN, three times daily for seven days, a single dose of 50 mg ISMN on the eighth day produced a fall in pulmonary artery mean pressure three hours after administration, of only 25% at rest and 20% on exercise, while the anti-anginal effect remained unchanged. Six hours after administration there were no significant changes in haemodynamic variables compared with the initial values. The reduced fall in pulmonary artery mean pressure during chronic administration is interpreted as the development of tolerance with decreased venous pooling, while the unchanged anti-anginal effect is explained by the site of action of the nitrate on the coronary arteries and on the collateral circulation with positive blood redistribution.

Adult↗
PubMed1983

Oral ISDN for the treatment of patients with acute myocardial infarction.

In a controlled randomized trial the effect of treatment with 60 mg orally administered ISDN in patients with acute myocardial infarction was studied. Besides the usual clinical investigations, hemodynamics were checked; pulmonary artery pressure and cardiac output during the first 4 days were measured. 509 patients were included in the trial. Based on other researchers' considerations about limitation of infarct size we formed a subgroup of 132 patients to be treated within 8 h after onset of symptoms. The mortality for the entire ISDN-group was not influenced compared with that for the control group. If treatment with ISDN was started within the first 8 h after onset of symptoms of acute myocardial infarction, mortality in this group was significantly lower than that in the control group. In the group of patients receiving treatment within the first 8 h we found positive effects: a fall of pulmonary artery pressure with consecutive rise of cardiac output, mainly in patients showing high left ventricular end-diastolic filling pressures. In the treated group we found a significant decrease in arrhythmias and angina pectoris. When left ventricular hemodynamics were tested before discharge from the hospital patients treated with ISDN during the first 8 h again showed favorable results. We conclude that treatment with ISDN in the early phase of acute myocardial infarction is beneficial particularly for patients with high left ventricular filling pressures.

Administration, Oral↗
PubMed1983

Hemodynamic effects of isosorbide-5-mononitrate in acute and chronic treatment of coronary heart disease.

Hemodynamic effects of isosorbide-5-mononitrate (IS-5-MN) were studied in 20 patients with coronary heart disease. Three hours after the first administration of 50 mg IS-5-MN we found a significant decrease in mean pulmonary artery pressure, while heart rate and arterial blood pressure remained unchanged. Concomitant with the hemodynamic effects we found a decrease in angina pectoris and normalization of exercise-induced ST depression. After 50 mg IS-5-MN three times daily for 1 week the repeated acute administration of a single dose of 50 mg produced a fall in mean pulmonary artery pressure at rest (-25%) and during exercise (-20%), while the antianginal effect was unchanged. Six hours after a repeated single dose we found no change in hemodynamic parameters as compared with the control levels before treatment. The decreased effect on the pulmonary artery pressure under chronic treatment is discussed as a development of tolerance with decrease of venous pooling. The unchanged antianginal effect is difficult to understand, and may be interpreted as due to an influence on the coronary vessels and collateral blood flow.

Aged↗
PubMed1982

[Long-term observation of arterial blood pressure after pacemaker implantation (author's transl)].

The behaviour of blood pressure after pacemaker implantation was investigated in 278 patients in a long-term follow-up. Prospective analysis was done in 151 patients and 127 patients were assessed retrospectively. Pacemaker implants were ventricle triggered demand systems. The observation period was between 18 and 80 months. After implantation lowering of systolic pressures can be expected. Provisional care for overcoming this stage is indicated., In the majority of patients blood pressure rises after 3 to 5 months to pre-implantation values. Drug treatment must consider these changes of blood pressure behaviour. Permanent decrease of systolic blood pressure was observed only in small number (5.8%) of pacemaker patients.

Aged↗
PubMed1982

Self-replication with errors. A model for polynucleotide replication.

A model for polynucleotide replication is presented and analyzed by means of perturbation theory. Two basic assumptions allow handling of sequences up to a chain length of v approximately 80 explicitly: point mutations are restricted to a two-digit model and individual sequences are subsumed into mutant classes. Perturbation theory is in excellent agreement with the exact results for long enough sequences (v greater than 20).

DNA Replication↗
PubMed1982

Preparing the patient for a barium enema: a comparison of nurse and patient opinions.

The purpose of this research was to explore possible differences in nurse versus patient opinions about patient education information appropriate for the barium enema procedure. Twenty-eight nurses and 30 patients participated in the study. Findings showed that nurses believed a patient should have more information than the patients believed a patient needs, and that patients wanted only minimal detailed information about events that will happen during the procedure. Rather, patients were interested in knowing the benefits and purpose of the procedure while nurses believed that this information should be provided by the physician and not the nurse. Finally, nurses were dissatisfied, in general, about their patient education information that they have given to patients in the past for a barium enema procedure.

Adolescent↗
PubMed1982

[Influence of betablocking agents with and without intrinsic sympathicomimetic activity (ISA) on local wall-motion disorders in patients with coronary heart disease].

UNLABELLED: A single blind randomized study on the effect of betablockers with (Pindolol = P, 0.4 mg i.v., n = 10) and without (Metoprolol = M, 5 mg i.v., n = 11) intrinsic sympathicomimetic activity (ISA) on local wall-motion abnormalities was performed in 21 patients with coronary heart disease in anterior wall hypokinesia. Before and 10 minutes after intravenous application of P or M strokes, volume index, cardiac index, heart rate, systolic and enddiastolic left-ventricular pressure were measured. The left-ventricular volumes were calculated biplane with the area-length method of Dodge and Sandler. Analysis of wall-motion disorders were performed by hemichord method measuring 7 hemiaxis and 1 long axis. RESULTS: Similar hemodynamic effects of both beta-blockers were found on LVEDP und LV-EDVI. Different effects were observed on heart rate and ejection fraction. With M heart rate and ejection fraction decreased, with P heart rate and ejection fraction increased significantly due to the intrinsic sympathicomimetic activity (ISA). Shortening of hypokinetic wall segments was improved by both P and M, shortening of non-hypokinetic contralateral segments, however, remained unchanged with P and decreased with M. With P shortening of chords was improved, whereas with M shortening of chords decreased. Our findings suggest that in therapy of patients with coronary heart disease differential use of beta-blocking agents with or without ISA has to be discussed.

Adrenergic beta-Antagonists↗
PubMed1982

[Runaway pacemaker caused by the defect of a Lem-Dynacor pacemaker (author's transl)].

Caused by the defect of a Lem-Dynacor pacemaker, a critical diminution of the period time till 20 ms developed. Fortunately, ventricular fibrillation did not occur because of diminution of the impulse amplitude beyond the threshold value of ventricular stimulation. Recognition of the defect with the ECG is possible if considered. It is easy to confuse with overlapping of alternating current.

Bradycardia↗
PubMed1982

[Hemodynamics of the St. Jude Medical aortic prosthesis in comparison to the Björk-Shiley and Lillehei-Kaster prostheses].

Pre- and postoperative hemodynamic data in 10 patients in whom the aortic valve was replaced by a St. Jude Medical (SJM) prosthesis are compared with those in 29 patients who received a Lillehei-Kaster tilting disk (LK) valve prosthesis and 11 patients with a Björk-Shiley tilting disk (BS) valve prosthesis. The SJM aortic prosthesis of the small size (A 21) has advantages over the LK and BS types, and it is therefore particularly suited to use in a small aorta. There are also good hemodynamic results for the larger sizes of the SJM prosthesis. As a result of the 85-degree opening angle and the favorable ratio between the inner and outer diameters of the valve (suture ring), there is only minor impedance of blood flow. The SJM aortic prosthesis thus involves a lesser degree of hemolysis than the BS and the LK. In spite of the promising hemodynamic data, however, long-term findings on the durability of the SJM prosthesis in vivo have not yet been published. It therefore seems to us justifiable, especially where the aorta is large, to continue to use BS prostheses.

Aged↗
PubMed1981

[Serial determination of carcinoembryonic antigen in the follow-up of patients with malignant tumours (author's transl)].

Carcinoembryonic antigen (CEA) was determined serially in 54 patients with malignant tumour (other than colorectal ones). Patients in remission (21), those resistant to treatment (16) and a group not receiving treatment (17) showed a good correlation between growth behaviour of the tumour and titre changes. Best correlation was in 21 patients who after treatment with cytostatic agents, hormones or radiation had objective signs of remission. Serial determination of CEA is thus of value in the control of treatment of malignant tumours other than those of the colorectum.

Adult↗
PubMed1981

Comments on "growth of a hypercycle" by King (1981).

The notion of hypercycles has been introduced (Eigen, 1971) in order to characterize a functional entity which integrates information stored in individual self-replicating elements. Commonly, these self-replicating elements compete, like polynucleotides do in test tube experiments (Spiegelman, 1971; Biebricher et al., 1981) or, like species do in nature. A single species is selected eventually together with its most frequent mutants and the less efficient competitors disappear. In order to suppress competition, specific coupling terms of second order - these are coupling terms which are proportional to the product of two population numbers or concentration - have to be introduced into the kinetic equations such a link has to extend to all members, requiring the formation of a closed catalytic cycle (Eigen and Schuster, 1979). The copying of polynucleotide sequences, like every transfer of information, can only occur with finite accuracy (Eigen et al., 1981). This physical restriction imposes a limit upon the content of information that can be transmitted. A higher content of information requires more precise replication. A more involved replication machinery, however, presupposes more information to build it. Thus, a single autocatalyst will not be able to increase its content of information over the given threshold. How does one escape from this vicious circle? Hypercycles present a solution to the problem: many information carriers coexist and may cooperate to build a more sophisticated and more precisely copying replication machinery. Optimization of growth rates has never been the goal for which hypercycles were conceived. Any first order process can proceed at a higher rate than a second order process if low enough concentrations are chosen. On the other hand, any realistic hypercycle involves both first and second order terms. At low concentrations first order terms provide for accumulation of material while at higher concentration second order terms stabilize cooperation. At which concentration level such a prevalence changes is a matter of quantitative values of rate parameters rather than of basic principle. An autocatalyst may outgrow a hypercycle under certain conditions but it can never solve the problem of integrating information.

Models, Chemical↗