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Biomedical subjects

D Adler

Publications and source records attributed to D Adler.

At least 145 records · Page 8Linked to original sources
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Time to dP/dtmax, a preload-independent index of contractility: open-chest dog study.

A mathematical model of left ventricular pressure (LVP) during isovolumic contraction in the time domain shows the following predictions: 1) td, the time from onset of contraction to dP/dtmax and (dP/dt)/P, reflect only the time-dependent aspects of contraction, and are independent of preload; 2) dP/dtmax depends on both preload and the time-dependent aspects of contraction. To test preload independence we reduced filling volume (FV) by the method of ventricular volume clamps with a remote-controlled mitral valve in 7 anesthetized open-chest dogs. A decrease in FV of 80 +/- 15% produced a 29 +/- 12% (p < 0.001) decrease in LVP, 34 +/- 13% (p < 0.001) decrease in dP/dtmax, 13 +/- 4% (p < 0.001) decrease in t-dP/dtneg, and no change in td (-3 +/- 5%, NS). The heart rate (HR) dependence on td was assessed in other 5 anesthetized open-chest dogs. HR was changed with atrial pacing (50-240 bpm). td was linearly and inversely related to HR in each dog, and at each HR: dobutamine lowered and propranolol elevated this relation when compared to control (p < .001, both). Since dP/dtmax occurs usually before the opening of the aortic valve, td is, thus, also afterload-independent. Conclusion. This study supports the theoretical predictions that td is independent of preload and that it can serve, at any given HR, as a reliable index of contractility, provided that dP/dtmax occurs before the opening of the aortic valve.

Animals↗
PubMedDate not supplied

Evaluation of time-dependent and quantitative properties of contraction from left ventricular pressure.

Several mechanical indices predicted from a model of cardiac muscle contraction are tested. In the in-vivo canine heart, dp/dtmax and t-dp/dt, the time interval from onset of contraction to dp/dtmax, were measured. The product of these parameters Ap = t-dp/dtmax was calculated. t-dp/dt was shortened when heart rate was elevated and remained constant when ventricular end diastolic volume was changed. Ap increased with augmentation of ventricular end diastolic volume. To achieve constant muscle length when heart rate is changed, analogous tension measurements (assigned as dT/dtmax, t-dT/dt and AT) of prestretched Walton Brodie strain-gauge arch had been taken instead of pressure measurements. In the experiments in which Tmax, maximal isometric tension, was not changed for various heart rates, AT was also unchanged. These results are consistent with the predictions that t-dp/dt and Ap can be used as two independent mechanical indices: 1) t-dp/dt for the evaluation of the "time-dependent properties" of contraction and 2) Ap, for the evaluation of the "quantitative properties" of contraction. The advantages of applying these two mechanical indices for use in the intact ejecting heart, instead of the well-established parameters Vmax and Po are emphasized.

Animals↗
PubMedDate not supplied

Educating for the future: a national survey of nursing deans about need and demand for nurse researchers.

If nursing doctoral programs are to meet the profession's need for research, they must produce scholars with the specific research foci and skills capable of meeting the profession's unique research demands. A national survey of deans and directors of schools of nursing was conducted to determine their opinions about the differing research foci that graduates of nursing doctoral programs should possess. A mail survey instrument was returned by 434 deans and directors of baccalaureate and higher degree programs who were queried about current and future need, contribution, and funding capability of researchers prepared with five different foci: psychosocial processes, biophysical processes, health care delivery systems and administration, education, and methodology and instrumentation. Deans recommended diverse research foci for both current and future researchers and indicated optimism about future funding for research. Although deans rated current and future professional contributions of researchers in the psychosocial domain most highly, they indicated that they believed current and future funding potential was greatest for biophysical researchers. These deans predicted that all types of nursing research endeavors will become increasingly important to the profession and the development of its theory base.

Curriculum↗
PubMedDate not supplied

S-phase fractions and DNA-ploidy of oropharyngeal squamous epithelium carcinomas compared with histologic grade, stage, response to chemotherapy and survival.

DNA-ploidy and the percentage of S-phase fractions in 55 primary oropharyngeal squamous epithelium carcinomas were measured by DNA-Flow Cytometry (FCM). The data were compared with the histologic grade, the stage and the response of the tumours to cytostatic chemotherapy. A significant correlation was found between the histologic grade and the mean percentage of S-phase fractions (p less than 0.01). No correlation could be found between the FCM measurement data and the tumour stage. Carcinomas with an amount from 4.0 to 10.4% S-phase fractions responded to chemotherapy by complete remission, and those with 10.0 to 13.3% S-phase fractions by partial remission. The group of non-responders could be subdivided into two subgroups: non-responders with low amounts of S-phase fractions (1.1-3.9%), and non-responders with very high amounts of S-phase fractions (11.6-16.6%). FCM data, histologic and clinical prognostic factors were summed up to a prognostic score. The number of score points showed a significant correlation to the length of survival in months after diagnosis of the tumour (p less than 0.00001). FCM may be used as an additional diagnostic tool for a better biological characterization of the neoplastic tissue, especially as an aid for grading, prediction of the response to chemotherapy and the length of survival.

Adult↗