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Biomedical subjects

M S Rosenzweig

Publications and source records attributed to M S Rosenzweig.

6 recordsLinked to original sources
PubMed1983

Two-dimensional echocardiographic detection of left ventricular wall impaction by mitral prosthesis.

Real-time two-dimensional echocardiographic (2DE) studies detected impaction of the Starr-Edwards mitral valve prosthesis with the left ventricular wall in eight patients (septum in seven, posterior wall in one). One patient with echocardiographic evidence of posterior wall impaction died; autopsy revealed grooving of the left ventricular posterior wall by the cage. Four of seven patients with ventricular septal impaction developed ventricular arrhythmias in the in-hospital postoperative period which were persistent and difficult to control in two patients, but were not fatal. None of the 22 patients without ventricular wall impaction had ventricular arrhythmias. 2DE appears to be a useful noninvasive technique in detecting left ventricular wall impaction by mitral prosthesis, a potentially lethal complication.

Adolescent↗
PubMed1982

Doppler evaluation of fetal hemodynamics.

Human umbilical hemodynamics was investigated in 27 pregnant patients with gestational ages from 29 to 43 weeks using a pulsed Doppler flowmeter. The signals were analyzed by Fast Fourier Transform using a minicomputer. Coherent averaging of the signals, along with the computation of maximum velocity, mean velocity and the first moment of Fourier spectra about the zero frequency axis were performed. Hemodynamic indices were measured utilizing a comprehensive feature characterization technique of the blood flow velocity waveform. It was observed that coherent averaging reduced spectral variance thus relatively simplifying the analyses. The Pulsatility Index based on the first moment of the Fourier spectra indicated a higher umbilical flow change during the fetal cardiac cycle, than that predicted by the peak velocity Pulsatility Index. We also observed a high Pulsatility Index in association with three cases of oligohydramnios indicating the possibility of an elevated placental circulatory impedance. Variation in the peak velocity up to 20% was also noted with fetal breathing movements. Further studies are necessary to determine the clinical relevance of these findings.

Female↗
PubMed1980

Unit cell hypothesis for Streptococcus faecalis.

The mass doubling times of exponential-phase cultures of Streptococcus faecalis were varied from 30 to 110 min by omitting glutamine from a defined growth medium and providing different concentrations of glutamate (ranging from 300 to 14 mug/ml). After Formalin fixation, cells were dried by the critical point method, and carbon-platinum replicas were prepared. The surface area and volume of cell poles seen in these replicas were estimated by a computer-assisted, three-dimensional reconstruction technique. It was found that the amount of surface area and volume of poles seen in these replicas were independent of the growth rate of culture from which the samples were taken. These observations were consistent with the unit cell model hypothesis of Donachie and Begg, in which a small number of surface sites would produce a constant amount of new cell surface regardless of the mass doubling time of the culture. However, measurements of the thickness of the cell wall taken from thin sections of the same cells showed that the cell wall increased in thickness as a function of the increase in cellular peptidoglycan content which occurs when the growth rate of this organism is slowed down by a decrease in glutamate concentration. Thus, it would seem that although the size of polar shells made by S. faecalis is invariant with growth rate, the amount of wall precursors used to construct these shells is not.

Cell Division↗
PubMedDate not supplied

Computerized evaluation of blood flow measurement indices using Doppler ultrasound.

The study involved computer-assisted analysis of Doppler blood flow signals from an in vitro experimental system utilizing a calibrated occlusive pulsatile pump, vinyl tubings of various dimensions, and human blood. The power spectra of these signals were obtained using the Fast Fourier Transform, and the peak and mean frequencies along with the first moments of the Fourier spectra around the zero-frequency axis were computed. These indices were evaluated using different flow rates and tubal dimensions. It was experimentally verified that the first moment provided a more linear measure of volume flow rate than that estimated by peak and mean velocities. Although the first moment cannot measure the absolute flow rate, it may serve as a better indicator of relative flow changes than the other two indices.

Blood Flow Velocity↗