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Biomedical subjects

K Redmann

Publications and source records attributed to K Redmann.

At least 19 recordsLinked to original sources
PubMed1992

Cardiodynamic effects of dopamine and dobutamine.

On 11 patients undergoing coronary surgery, at the end of the surgical intervention, the inotropic responses to 0.4 and 0.8 microgram x kg-1 x min-1 dopamine and dobutamine given via the aorto-coronary bypass directly into the coronary artery were compared. These dosages correspond to ones 10 times greater applied intravenously. The measurements were made using needle force probes which were implanted into the myocardial offstream area in the left ventricular wall. Bypass flow was measured simultaneously by an electromagnetic flow probe. There is a significant increase in coronary bypass flow induced by both rates of 0.4 and 0.8 microgram x kg-1 x min-1 dobutamine, but there was no significant effect on bypass flow induced by dopamine. Developed myocardial force is raised more by dobutamine medication than by dopamine. However, the rate of contraction increases significantly and relaxation is significantly accelerated by dopamine at both dosages. A significant increase in rate of contraction and relaxation was only induced by the higher dosage of 0.8 microgram x kg-1 x min-1 dobutamine.

Aged↗
PubMed1991

Quantitative assessment of the effects of 'inodilators' on the myocardium in patients without primary cardiac insufficiency after coronary surgery: Part I--Amrinone.

The positive inotropic and peripheral vasodilating effect of amrinone has been measured in 20 patients without manifest cardiac insufficiency during the early (8-18 h postoperative) and late (18-48 h postoperative) recovery phase after coronary surgery. On conclusion of the surgical intervention first the aortocoronary bypass flow was compared during dobutamine and amrinone administration. It increased by 88% with amrinone and by 19% with dobutamine. Then a needle force probe was implanted in the myocardium. Directly measured local myocardial force increased not significantly by 3.5% after the first and by 5.1% after the second bolus injection of 2 mg/kg amrinone. The rate of myocardial contraction increased by 18.7% and 12%. The rate of relaxation decreased by 5.3% after the first and increased by 15% after the second injection. Mean pulmonary arterial pressure fell from 18.5 to 15.5 mmHg and from 19.7 to 17 mmHg. Cardiac output increased by 23% after the first and by 20% after the second injection. Heart rate rose from 88 to 99 bpm and from 86 to 94 bpm. Total peripheral resistance fell from 1,035 to 706 dyn*s*cm-5 and from 1,036 to 819 dyn*s*cm-5. The systolic arterial pressure fell from 132 to 116 mmHg after the first injection and did not change after the second injection. Amrinone was found to be a powerful peripheral vasodilator with a mild positive inotropic action. The variations in the effects between the early and late recovery phases mainly reflect a progressive haemodynamic stabilization with a decreasing tendency toward hypotensive disregulation. Careful consideration has to be paid to a properly balanced filling of the vascular system before administering amrinone.

Adult↗
PubMed1991

Quantitative assessment of the effects of 'inodilators' on the myocardium in patients without primary cardiac insufficiency after coronary surgery: Part II--Enoximone.

Twelve patients undergoing routine coronary artery surgery received a bolus injection of 1.5 mg/kg enoximone between 8 and 18 hours and again between 18 and 48 hours after operation. No patient showed clinically manifest myocardial heart failure. The haemodynamic and cardiodynamic response to enoximone was quantified over a 30 minutes period following injection. Local myocardial developed force increased by 24 +/- 7% after the first and by 12 +/- 6% after the second injection. The rate of myocardial contraction increased by 50 +/- 14% and 15 +/- 10%, respectively, and relaxation increased by 35 +/- 14% and 22 +/- 19%. There was a decrease in total peripheral resistance of 38.8 and 42.9%, and an increase in heart rate of 11 and 15%. The mean arterial pressure showed small reductions from 73 (+/- 3.7) to 67 (+/- 2.6) mmHg for the first dose and from 83 (+/- 3.1) to 78.4 (+/- 2.8) mmHg for the second. Central venous and pulmonary artery pressures were essentially unaltered. The substantial positive inotropic effect of enoximone has been shown to match its peripheral vasodilatory activity, so that in the normovolaemic patient there is a clinically insignificant small fall in mean arterial pressure.

Aged↗
PubMed1991

[Comparison of new cardiac agents using differential therapeutic criteria].

Positive inotropism, reduction in preload, and reduction in afterload induced by any cardiacum are not exactly quantified in humans, nor are the patients classified as to their respective requirements. Also, any of these drug activities change with the patient's instantaneous cardiac and hemodynamic functional state. One reason for incomplete knowledge is a shortage of methods which allow to assess the inotropic state of the myocardium. In 17 patients, age range 56-76 years (two females, 15 male), undergoing routine coronary surgery, informed consent was obtained for implantation of a needle transducer for measurement of wall force. At the end of coronary surgery, developed myocardial force and aorto-coronary bypass flow were measured electromagnetically. After control measurements, 0.03, 0.06 and 0.1 mg/kg enoximone were injected slowly (3 min per dose) into the aorto-coronary bypass. Eight to 18 h after surgery, and again 18-48 h after surgery, the following measurements were made, first as a control, and then after 1.5 mg/kg enoximone i.v.: aortic pressure (AoP), central venous pressure (CVP) and pulmonary artery pressure (PAP), cardiac output (CO), and heart rate (HR). Peripheral vascular resistance (TPR) was calculated. Developed force and its derivatives were recorded continuously. Immediately after recovery from cardioplegia a 0.19 mg/kg dose of enoximone injected over 9 min into the aorto-coronary bypass induced an increase in bypass flow of 64 +/- 30%. Mean arterial pressure (MAP) showed a fall 5 min after enoximon injection on both occasions. The values were 73 (+/- 3.7) to 67 (+/- 2.6) mmHg, and 83 (+/- 3.1) to 78 (+/- 2.8) mmHg, respectively. The increase obtained in cardiac output (CO) 6.0 (+/- 0.4) to 7.4 (+/- 0.7) l.min-1, and 6.2 (+/- 0.7) to 8.5 (+/- 1.3) l.min-1 was significant at 5 min and remained so at 30 min on both occasions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Cell electrophoretic and absorption spectrographic investigations of the indirect effect of ultraviolet light on erythrocytes of patients with myocardial infarct and other illnesses].

In 34 patients with myocardial infarct, 14 patients with arterial circulatory bleeding disturbances and 12 dialysis patients, blood was diluted immediately after collection by using an Eagle medium (MEM) which had been irradiated by ultraviolet rays. The erythrocytes of patients with myocardial infarct and circulatory bleeding disturbances responded with a mean increase of negative net surface loading by roughly 6% related to the controls in not-irradiated medium. In the erythrocytes of dialysis patients we found no changes of this kind. After ultraviolet irradiation the uv/vis absorption spectra of the Eagle medium showed an increase of extinction depending on the dosage in the short-wave range and a decrease in the long-wave range. Apparently, these uv-induced changes in the Eagle medium secondarily cause an increase of the surface loading of erythrocytes. In patients with arterial circulatory bleeding disturbances this effect which affects the electrostatic relations particularly in the area of terminal flows could contribute to improving the stability of suspension in the blood, thus having a therapeutic importance for these patients as far as their microcirculation is concerned.

Blood Coagulation Disorders↗
PubMed1990

[Effect of ultraviolet light on the UV/VIS absorption spectrum of components of Eagle (MEM) cell culture medium].

The impact of ultraviolet light on uv/vis absorption spectra of selected individual components of the cell breeding medium according to Eagle (MEM) was investigated. The strongest alterations of light absorption were detected in L-phenylalanine, L-tyrosine and L-tryptophan. Thus, the absorption behaviour of the Eagle (MEM) medium changed post radiation may be attributed to spectrophotometric alterations of absorption in aromatic amino acids. The results are discussed with regard to the effect on the surface charge of erythrocytes.

Culture Media↗
PubMed1990

[High-frequency ventilation: side effects and dangers].

Dangers of high-frequency ventilation result from the lack of a sensitive monitoring technique. Mucosal lesions of the trachea and the bronchi as well as cooling of the patient can be prevented by adequate humidification and heating of the gas flow. It is still controversial whether HFV leads to increased mucus production or secretolysis, and whether it prevents or promotes aspiration. The influence of mobilisation or immobilisation of a pulmonary focus on its recovery is not well understood. Interferences of HFV with the autonomic nervous system and endocrine system, like an increased release of PGI2, an antidiuretic and narcotic effect, with the coagulation system and the acid-base balance are inconsistent and therefore need particular clinical observation.

Animals↗
PubMed1988

[High frequency ventilation. Study of the mechanisms of action].

Dried lungs and isolated bronchial trees dissected from large animals were submitted to high-frequency oscillation and jet-ventilation. The pattern of intrapulmonary pressure distribution and CO2 diffusion were measured through transalveolar chambers fixed to the perforated pleural surfaces and through airbags pasted on the isolated bronchial trees. Under oscillating conditions, the pressure profiles in different lung and bronchial compartments were inhomogeneous and frequency dependent; the pressure-wave amplitude was proportional to the oscillation frequency. On the other hand, the inhomogeneities found with jet-ventilation were mostly dependent on the airflow direction and position of the intratracheal cannula. Since these inhomogeneities were similar on dissected lungs as well as on isolated bronchial trees, it was concluded that they were essentially dependent on endobronchial aerodynamic effects. But the absence of the in vivo pulmonary and bronchial elastic recoil certainly modified the effects of these ventilation modes with respect to accepted clinical findings. Also results were shown to vary between individuals and within individuals, probably explaining the divergent results obtained by different authors.

Animals↗
PubMed1988

The problem created by myocardial structure in assessing function.

The clinical understanding of the dynamics of myocardial contraction is hampered by an over-simplified interpretation of the intramural pattern of force generation. This limits the anaesthetist's knowledge of the direct effects of commonly used anaesthetics. A discrimination between a negative inotropic effect and changes in pre- and afterload is usually impossible in clinical conditions. By using needle force probes, it is now possible to measure intramyocardial mesh tension in volumes as small as 3 mm3. Force mapping in 20 to 30 layers of the hearts of five normal dogs has shown that there are different patterns in the basal, middle and apical portions of the free wall of the left ventricle. An inhomogeneity is also observed when myocardial hypertrophy is produced by a 6-week period of aortic banding. However, this decreased the gradient in wall tension between the basal and the other portions of the ventricle. Inhomogeneities in wall tension increase the difficulty of assessing the contractile state of heart muscle. It may, however, be useful to compare local wall dynamics in the more isometrically-contracting basal segment with those in the middle portion which brings about most of the emptying of the ventricle. In the future, transoesophageal echocardiography may be used to measure variations in wall thickness which change the global loading conditions in the basal midwall compartments of the left ventricle.

Animals↗
PubMed1988

[High-frequency artificial respiration. II. Intratracheal high-frequency pressure changes with a rotation-valve catheter].

From the history of ventilatory support, the early studies of Auer und Meltzer only now seem to find a functional explanation. A rotating valve mounted on the tip of an endotracheal tube delivers a widespread gas bolus. The turbulent flow acts as a stirring device on the intrapulmonary gas volume. The method reduces the directional selectivity that typically limits the efficiency of jet ventilation. Systematically changing the rotational frequency between 10 and 80 Hz allows sequential stimulation, compartment by compartment, of the entire lung, which also gives rise to frequency-dependent local air-trapping that sequentially inflates different compartments. Jet ventilation and high-frequency oscillation were compared in dogs with the rotating valve tube by taking blood gas samples from 4-6 intrapulmonary veins: jet ventilation is characterized by preponderant ventilation of lung compartments opposite the lower aperture of the endotracheal tube. High-frequency oscillation induces a frequency dependent repartition of alveolar ventilation. The rotating valve tube definitely contributes to the homogenisation of alveolar ventilation in a manner that is less dependant upon segmental compliance than conventional ventilation.

Animals↗
PubMed1986

Flow cytometric estimation of transmembrane potential of macrophages--a comparison with microelectrode measurements.

Potential-dependent accumulation of the lipophilic cationic dye 3,3' dihexyloxacarbocyanine (DiOC6(3)) in macrophages has been investigated. Resulting fluorescence of cells was measured by flow cytometry. Alterations of membrane potential of macrophages were induced by ionophore treatment (valinomycin and gramicidin) in a dose-dependent (10(-5) M-10(-7) M) and time-dependent (0 min-45 min) manner. Resulting changes in relative fluorescence intensity were compared with changes of transmembrane potential measured by intracellular recordings obtained by applying glass microelectrodes. The comparative studies offer the possibility to calibrate the flow cytometric estimate of membrane potential of suspended cells. Equilibration of dye partition between cells and surrounding medium is strictly potential-dependent at dye concentrations between 5 X 10(-8) M and 10(-7) M and within an incubation interval from 10 min up to 30 min after addition of dye. Conclusions are drawn concerning the field of application of the optical method. Dynamics of electrical processes following ionophore treatment are discussed in terms of molecular mechanisms of altered ionic transport.

Animals↗
PubMed1986

[Pretherapeutic testing of sensitivity to cytostatic drugs in primary cultures of selected urologic tumors].

In 30 patients with malignant urologic tumours (scrotal tumours, renal tumours, tumours of the urinary bladder) an in vitro cultivation of the primary tumor was tried. According to the technique of Tannenberger and Bacigalupo 21 primary cell cultures could be applied. This corresponds to an accession rate of 70%. After formation of a cell lawn and addition of cytostatics of the arbitrarily selected medicaments vinblastin, bleomycin, cis-DDP, actinomycin D the reaction of the cells on the drugs was judged light-microscopically and electrophysiologically by measuring the transmembrane potential 24 hours after the application of medicaments. Thus apart from a usual oncobiogram which has as its fundament the morphology of the cells an electrooncobiogram could be established. The authors dealt with the methodology of the TMP-measurement after Redmann as a relatively new method for the pretherapeutic sensitisation test of tumours. The reactions of the cells to the cytostatics mentioned were so multifarious in the 3 groups of tumours that no conclusions of general validity could be drawn. These different modes of reaction are to be regarded as an expression of the biological individuality of human tumours. Apart from answering theoretical questionings the TMP-measurements might be used in the pretherapeutic sensitisation test of cytostatics in malignant renal tumours.

Antineoplastic Agents↗
PubMed1986

Membrane hyperpolarization following chronic exposure of FL-cells to low doses of ouabain.

The transmembrane potential (TMP) of FL-cells (monolayer cultures) in Eagle's medium with ouabain concentrations from 10(-4) to 10(-11) M was measured by means of glass microelectrodes over 96 h. High ouabain concentrations caused total depolarization of the cell membrane with subsequent cell death after 24 to 48 h. A level of 10(-7) M ouabain was tolerated by the cells over 96 h, and the TMP was decreased about 50% vs. controls in ouabain-free medium. Ouabain at concentrations from 10(-11) to 10(-8) M increases TMP by 20-40%, which decayed after 24 to 48 h. The low glycoside concentrations are assumed to cause, if only part of the glycoside receptors (Na+ pumps) is blocked, an activation of the still active pumps (turnover) and enhanced formation of transport enzymes and their incorporation into the membrane (replacement) so that the overall result is a stimulation of the cell membrane transport systems.

Cell Line↗