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Biomedical subjects

J Newald

Publications and source records attributed to J Newald.

At least 19 recordsLinked to original sources
PubMed1991

Cardiac dysfunction after acute endotoxin administration in conscious sheep.

We evaluated cardiac function in an unanesthetized ovine model of hyperdynamic endotoxemia. The animals were instrumented for crystallographic dimension analysis of the left ventricle (LV) and measurement of LV, aortic, atrial, central venous, and pulmonary arterial pressures, and cardiac output. Seven sheep received 1.5 micrograms/kg of Escherichia coli endotoxin [lipopolysaccharide (LPS) LPS-P group] and were compared to a sham group. The sham group demonstrated no significant change in any of the variables. In the LPS-P group, the cardiac index increased (5.7 +/- 0.4 to 7.9 +/- 0.6 l.min-1.m-2) between 8 and 12 h after LPS. Concomitantly, the maximum elastance of LV end-systolic pressure-volume relations significantly decreased (2.88 +/- 0.27 mmHg/ml) compared with baseline (3.89 +/- 0.50 mmHg/ml). Other indexes of the LV contractility (maximum pressure development and ejection fraction) were also reduced. There was a simultaneous increase in the LV end-systolic and diastolic volumes. These findings confirm the hypothesis that there is a myocardial depression during LPS in the ovine model.

Animals↗
PubMed1991

Cardiac function in an ovine model of endotoxemia.

Eight awake sheep were monitored with ultrasonic crystals, positioned at the anterior and posterior left ventricular wall. A left-sided intraventricular pressure transducer and a right ventricular ejection fraction catheter were positioned in the right and left hearts, respectively. After administration of endotoxin (Escherichia coli, LPS 1.5 micrograms/kg in 30 min), the hemodynamic variables showed a triphasic course. Phase I, (0-1 hr post LPS) was characterized by an increased pulmonary artery pressure and a decreased right ventricular ejection fraction. The inability of the right ventricle to compensate for the increased preload resulted in a fall of the left ventricular preload, stroke volume, and cardiac output. Three hours after LPS administration a second drop of the cardiac output was noted (phase II). This occurred as a result of a fall in preload. Eight hours post LPS a hyperdynamic phase (phase III) was distinguished, with a high cardiac output and a low systemic vascular resistance. During this time there was evidence of probable reduced myocardial contractility.

Animals↗
PubMed1988

Control of perfusion pressure and flow in isolated heart bioassays.

Bioassays using isolated animal hearts are important tools for the investigation of cardiac behaviour, but to obtain accurate results a proper perfusion circuit has to be designed. In particular, biophysical studies of contractile and vascular behaviour require a perfusion circuit which permits the adjustment of several experimental parameters within wide ranges. It must also be able to maintain the stability of these parameters when the behaviour of the isolated organ undergoes major changes. To meet this requirement, we have developed a perfusion circuit which makes it possible to control either the perfusion pressure or the coronary flow, with a high degree of precision. There is an electronic controller which satisfies the requirements of a variety of safety and experimental requirements and guarantees a well-defined perfusion system. Computer simulation of the interaction between the perfusion circuit and the heart identified the basic elements of this time-variable, nonlinear system.

Animals↗