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Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 757 records · Page 42Linked to original sources
PubMed1975

A model for the assessment of left ventricular compliance: effect of hypertrophy and infarction.

Non-linear elastic theory was applied to the problem of diastolic filling of the left ventricle, which was treated as a thick-walled sphere. The mathematical model was used to predict pressure-volume relationships for ventricles with various initial dimensions and myocardial elasticity constants. A resonable agreement was obtained with data reported in the literature. The results may provide a basis for the use of empirical compliance indices.

Animals↗
PubMed1975

A study of the electroencephalogram during surgery with deep hypothermia and circulatory arrest in infants.

Seveteen infants (2 1/2 to 28 months old) were continuously monitored by six-channel electroencephalography (EEG) during the entire surgical procedure of open-heart repair. They were subjected to surface hypothermia supplemented by cold extracorporeal circulation (ECC) down to an average esophageal temperature of 21 degrees C., to cardiac arrest of 40 minutes average (range 19 to 62 minutes), and to ECC rewarming. Survival time of the EEG was correlated to esophageal temperature at the time of arrest. EEG reappeared an average of 26 minutes (5.30 to 50) after the strat of rewarming ECC and became strictly continuous after 44 minutes. Reappearance latency was well correlated with the duration of arrest. Potential normalization was oberved in 13 infants, but true normalization was observed in only 2 infants during the 90 to 120 minute period after ECC. By judging the EEG and by comparing this series with two previous series of moderate and deeper hypothermia in older patients, we concluded that the immediate tolerance of the brain to deep hypothermia and circulatory arrest seems no different in infants and in older patients.

Body Temperature↗
PubMed1975

[Interactions between prostaglandins E2 and F2alpha and isoprenalin in the dog heart in situ].

The effects of PGE2 and PGF2alpha on the isoprenaline induced elevation of myocardial contractility were studied on hearts of anesthetized dogs. The steady state effects were determined after single or simultaneous infusion of the substances. Two indices of contractility were used for the quantification of inotropic effects. PGE2 but not PGF2alpha showed positivinotropic effects. PGE2 significantly inhibited the inotropic responses induced by isoprenaline (p less than 0,01); whereas PGF2alpha was without any effect in this direction. The results are discussed with respect of a postjunctional action of PGE2.

Animals↗
PubMed1975

Dynamic spine alloplasty (spring-loading corrective devices) after fracture and spinal cord injury.

Dynamic alloplasty in spine fractures is a method of stabilization of the fracture site of the injured spine by obtaining a steady, gradual correction of the spine in accordance with Guttman's method. Gait training may begin within 2 weeks after surgery. The method shortens the rehabilitation time of paraplegics to approximately 3 months, as compared with the conventionally treated group. Dynamic spine fitting not only enables the patient to accept his disability, take interest in vocational and social rehabilitation sooner than conventional methods, but also prevents the typical psychological and physiological complications, such as depression, neurasthenic status, urological complications and bedsores. There is no need for prolonged muscle reconditioning because the patients are immobilized only for the essential postoperative period. Following our research on "Amputations with Immediate Prosthetic Fitting," we sould like to propose the term "Immediate Functional Paraplegic Fitting" for this technique.

Adolescent↗
PubMed1975

[Computer analysis of ventricular pressure recordings: evaluation of myocardial contractility on the dog heart in situ].

The contractile indices Vmax (maximum shortening velocity of the contractile element) and ARPD (power averaged rate of power density generation) which have been shown to be unaffected by alterations in preload and afterload were computed from isovolumic left ventricular pressure data of dogs. The two indices were tested for their ability to detect changes in contractility induced by a positive inotropic drug (Isoprenalin). Whereas a good correlation was found between ARPD and Vmax (coefficient of correlation 0,895) the index ARPD was more sensitive to augmentation of myocardial contractility; also because it is simpler to obtain computationally and more appropriate for the intact heart from a theoretical point of view. ARPD should be useful especially for quantification of acute changes in myocardial contractility.

Analog-Digital Conversion↗
PubMed1975

[Variation of mechanical and biochemical parameters of pressure-loaded rabbit hearts following chronic administration of dipyridamole].

After constricting the aorta ascendens of rabbits, the influence of chronic administration of dipyridamole (8 mg/kg i.m. on 6 out of 7 days of the week for 3 months) upon heart hypertrophy, hemodynamics and the hydroxyproline content in the right and left ventricles, the incorporation rate of 2-[14C]-glycine into the actomyosin and soluble protein of the left ventricle was studied. The dipyridamole treatment had no effect on the increase in systolic pressure, the contractility index of the aorta-stenosed animals and heart rate. In contrast, the hypertrophic development, and consequently the increase in hydroxyproline concentration and the increased incorporation rate of 2-[14C]-glycine into the soluble protein were inhibited. The possible mechanism of action of dipyridamole on the development of heart hypertrophy in the rabbit is discussed.

Animals↗