In five canine heart-lung preparations the preload dependence of dP/dt max, V max, VCE max and (dP/dt:P-EDP + C) max was related to the inotropic sensitivity of these indices. V max and (dP/dt:P-EDP + C) max are less affected by preload changes than dP/dt max and therefore should be more suitable for inotropic measurements. But even if the preload changes caused by inotropic interventions are not taken into account, V max shows the same inotropic sensitivity as dP/dt max when the contractile state is reduced and an even lower sensitivity when the contractile state is enhanced. The sensitivity of (dP/dt:P-EDP + C) max, however, is much lower over the whole range of tested inotropic states. If enddiastolic pressure is kept constant during inotropic interventions, dP/dt max is a much more sensitive inotropic index than V max. VCE max usually shows a negative correlation to the diastolic filling of the heart. In the improved inotropic state this correlation can become positive, thus making it impossible to evaluate the influence of the preload dependence on the result. None of the tested parameters shows a higher inotropic sensitivity than dP/dt max, though the preload dependence of dP/dt max is more evident. Therefore, none of these more complicated parameters has any advantage over the simple measure dP/dt max for evaluation of acute changes in contractility.

Animals↗

PubMedDate not supplied

Maximal rate of pressure rise and time parameters in the right ventricle under isovolumic conditions. Investigations in the canine heart-lung preparation.

In contrast to the left ventricle, the maximal rate of intraventricular pressure rise in the right ventricle does not occur within the isovolumic phase of the contraction. Occlusion of the pulmonary artery by inflation of a balloon during the diastole causes an isovolumic systole of the following heart beat. The canine heart-lung preparation was used to test whether dP/dtmax measured isovolumically and the peak ventricular pressure Pmax as well as the parameters derived are useful indices for the contractile state of the right ventricle. Changes only of the aortic pressure influence neither dP/dtmax, Pmax and the time values from the onset of contraction to dP/dtmax (t-dP/dtmax), nor the time to Pmax (t-Pmax). A rise in heart frequency leads to an increase in dP/dtmax and Pmax at lowered enddiastolic pressure. It does not influence the time interval t-dP/dtmax and t-Pmax. With augmented diastolic filling, dP/dtmax as well as Pmax increase, and t-dP/dtmax and t-Pmax are extended. The present study suggests that dP/dtmax and Pmax measured isovolumically provide accurate and practical measurements of right ventricular contractility, provided that changes in enddiastolic pressure and heart frequency are taken into account. The time parameters are found to be not useful.

Animals↗

PubMedDate not supplied

The maximal rate of pressure rise in the right ventricle of isolated canine hearts in isovolumic and auxotonic systole under various hemodynamic and inotropic conditions.

The influence of changes in pre- and afterload, heart frequency and inotropic state on the difference between right ventricular dP/dtmax measured isovolumically and auxotonically has been investigated in canine heart-lung preparations. Isovolumic systoles were obtained by occluding the pulmonary artery during diastole by balloon inflation. The mean difference between isovolumic and auxotonic dP/dtmax is 40 mm Hg/sec (15 to 80 mm Hg/sec) - i.e. about 10% of the value measured auxotonically. Neither hemodynamic (pre- and afterload changes) nor inotropic changes influence this difference. Heart rate increase from 140 to 200/min also has no effect. This corresponds with the unchanged time interval between pulmonary valve opening and right ventricular dP/dtmax under all these conditions. Only heart rates below 100/min seem to enhance the difference between isovolumic and auxotonic dP/dtmax. Since the difference is not altered at various inotropic states, the result of this study leads to the conclusion that the relative changes in contractility could be slightly overestimated by using the auxotonic dP/dtmax for inotropic assessment. Practically, this inexactitude is within the error range of the method. Therefore, the use of dP/dtmax measured auxotonically does not introduce a marked disadvantage related to isovolumic dP/dtmax for assessment of relative inotropic changes of the right ventricle in isolated hearts.

Animals↗

PubMedDate not supplied

Cell-cycle dependent mutation of human lymphoblasts: bromodeoxyuridine and butyl methanesulfonate.

Cells of the human lymphoblast line WI-L2 and its derivative TK-6 were synchronized by centrifugal elutriation and cell-cycle dependent mutation to 6TGR (HPRT) and OUAR (Na+, K+ ATPase) measured. Bromodeoxyuridine induced 6TGR and OUAR mutations within S phase while butylmethyl-sulfonate induced mutation displayed no cell-cycle dependence. The data indicate that centrifugal elutriation is a facile means to obtain a useful degree of synchrony for these cell lines.

Bromodeoxyuridine↗

PubMedDate not supplied

[Success rates of midfacial fracture treatment].

295 patients with midfacial fractures were treated on an inpatient basis between 1975 and 1989. 185 patients underwent a follow-up examination. Discomfort was reported by patients in 43% of the cases, whereas pathological clinical findings were observed in 39% of the patients followed up. The late sequelae, which were only slight in extent, were increasing in frequency with the severity of the injury. The use of miniplate osteosynthesis resulted in improved clinical results. Apart from early diagnosis, immediate referral to a specialized hospital and immediate therapy, more emphasis must be placed on interdisciplinary cooperation.

Adolescent↗

PubMedDate not supplied

Mutation assay in diploid human lymphoblasts: methodological aspects.

The protocol for a recently developed quantitative assay for mutation at the hgprt locus of human lymphoblasts is presented. Practical problems affecting ease of performance and reliability are discussed with the aim of making the assay available for assessment and possible use in other laboratories.

Cell Line↗