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At least 19 recordsLinked to original sources
PubMed1979

Laser flow cytometric light scatter and fluorescence pulse width and pulse rise-time sizing of mammalian cells.

In laser flow cytometry, an increasingly popular technique of analytical cytology, quantitative measurements of interest include cell and nuclear diameters. Electronic circuitry for a new cell sizing technique has been developed which measured the time that signal pulses from either fluorescence or light scatter sensors exceed a preset constant fraction of the peak signal amplitude (pulse width) or the time that it takes a signal to rise between constant fractions of the peak signal amplitude on the rising side of the pulse (pulse rise-time). These pulse width or pulse rise-time measurements were related to cell or nuclear diameters and were used in combination to determine nuclear size to cell size ratios. This method of sizing was found to be independent of fluorescent or light-absorbing stain intensity, linearly related to cell or nuclear diameter, and capable of resolving small diameter differences.

Animals↗
PubMed1976

Rapid evaluation of many pulse echo system characteristics by use of a triggered pulse burst generator with exponential decay.

A pulse burst generator is utilized in which the pulses are triggered by the transmitter pulse of the ultrasound system being tested. The pulses are spaced the equivalent of every 2 mm in the body, and their amplitude decays with 0, 1.25, or 2.5 dB/cm over greater than a 50 dB dynamic range. By replacing the ultrasound transducer with the pulse generator, one can record quite easily the accuracy of depth gain compensation (DGC) and of distance measurements in A mode and B mode. If the DGC on the ultrasound unit can be turned to zero, the unit's A mode display characteristic and B mode gray scale curve can be determined rapidly and the receiver gain control or attenuator can be calibrated. Measurement of a receiver signal-to-noise ratio is possible, and more quantitative imaging should be facilitated as well.

Evaluation Studies as Topic↗
PubMed1975

Computation of aortic pulse wave velocity and aortic pulse wave velocity and aortic extensibility from pressure gradient measurements.

This study is concerned with the computation of aortic pulse wave velocity based on simultaneous recordings of the aortic pressure gradient and first-time derivative of aortic pressure. These variables were recorded by means of a double-lumen catheter introduced in the aorta of four anesthetized closed chest dogs, and connected to critically damped manometer systems. Results of aortic pulse wave velocity were then compared: (i) to the true phase velocity obtained from spectra of apparent phase velocity, and (ii) to the pulse wave velocity computed from the time shift between maximum slopes of the pressure wave. From the aortic valves to 37 cm down the aortic trunk, pulse wave velocity increased from 410-460 cm/s to approximately 600-800 cm/s. Based on the wave propagation equation presented of Bramwell and Hill (Bramwell, J.C., and Hill, A. V. 1922. Proc. R. Soc. 93, 298-306), volumetric extensibility coefficients were computed from pulse wave velocity data. Results indicated that, from the aortic valves to 37 cm down to the aorta, the mean volumetric extensibility decreased from 0.43-0.56% deltaV/cm H2O to 0.16-0.25% deltaV/cm H2O (1 cm H2O = 94.1 N/m2).

Animals↗
PubMedDate not supplied

Pulse volume recordings in outer ear canal in pulse synchronous tinnitus. A comparison between ears with Glomus tumour, serous otitis media, and normal ears.

With the aid of a volume flowmeter it is possible to record pulse synchromous volumetric changes in the outer ear canal. In 7 ears with glomus tumour in the tympanic cavity and in 5 with serous otitis media, such changes were larger than in 125 persons with a normal middle ear. By changing the ambient pressure in a pressure chamber and instructing the patients not to swallow, the drum can be pushed inward or outward. In all the cases of glomus tumour studied the pulse volumetric change was considerably affected when the drum was pushed inward or outward. In the normal patients the change was no change at all. This means that the pulse volume changes in normals are generated mainly by the vessels in the outer ear canal.

Adolescent↗
PubMed1977

Turbulence measurement by the pulse luminescence method using a nitrogen pulse laser.

In order to visualize and measure with ease the velocity distribution and diffusion of turbulent flow, the pulse luminescence method was investigated. Turbulence intensity was obtained from the turbulent diffusion patterns by Taylor's diffusion theory. Apparatus was developed for easier measurement. A nitrogen pulse laser was used for instantaneous, high-power excitation. With the use of a night vision scope a bright image was recorded by a TV camera and video tape recorder. The optimum concentration of LC-G1A luminescent particles was about 0-05% wt for the measurement. High fidelity of the particles as an indicator of the fluid velocity was confirmed. It was demonstrated that the turbulence intensity could be visualized and measured quantitatively by the pulse luminescence method.

Lasers↗
PubMed1975

The triple pulse generator: Clinical evaluation of a new multipurpose external pulse generator.

This report describes our experience with a new, versatile battery operated, multi-purpose pulse generator especially designed for the electrophysiological investigation and treatment of cardiac arrhythmias in man. The unit was constructed according to our specifications and has been clinically in 75 patients over a period of 18 months. We have found the triple pulse pacemaker safe, reliable and functioning precisely according to specifications both clinically and when repeatedly checked with a storage oscilloscope.

Arrhythmias, Cardiac↗
PubMed1977

Studies on proinsulin and problucagon biosynthesis and conversion at the subcellular level. II. Distribution of radioactive peptide hormones and hormone precursors in subcellular fractions after pulse and pulse-chase incubation of islet tissue.

Anglerfish proinsulin and insulin were selectively labeled with [(14)C]isoleucine, while proglucagon, conversion intermediate(s), and glucagon were selectively labeled with[(3)H]tryptophan. After various periods of continuous or pulse-chase incubation, islet tissue was subjected to subcellular fractionation. Fraction extracts were analyzed by gel filtration for their content of precursor, conversion intermediate(s), and product peptides. Of the seven subcellular fractions prepared after each incubation, only the microsome and secretory granule fractions yielded significant amounts of labeled insulin-related and glucagon-related peptides. After short-pulse incubations, levels of both [(14)C]proinsulin and [(3)H]proglucagon (mol wt approximately 12,000) were highest in the microsome fraction. This fraction is therefore identified as the site of synthesis. With increasing duration of continuous incubation or during chase incubation in the absence of isotopes, proinsulin, proglucagon, and conversion intermediate(s) are transported to secretory granules. Conversion of proinsulin to insulin and proglucagon to a approximately 4,900 mol wt conversion intermediate and 3,500 mol wt glucagon occurs in the secretory granules. Converting activity also was observed in the microsome fraction. The recovery of most of the incorporated radioactivity in microsome and secretory granule fractions indicates that the newly synthesized islet peptides are relegated to a membrane-bound state soon after synthesis at the RER is completed. This finding supports the concept of intracisternal sequestration and intragranular maintenance of peptides synthesized for export from the cell of origin.

Animals↗
PubMed1977

Distortion of non-invasive cardiac pulse curves. A capillary-damped pick-up and a calibration unit forapex cardiograms and other pulse curves.

A calibration unit and a capillary-damped pick-up, of funnel type, intended for apex cardiograms and other non-invasive cardiac pulse curves are presented. The physical properties of a recording system, suitable for non-invasive cardiac diagnostic techniques, are reviewed. In 4 identical recording units consisting of a funnel with and without capillary damping, connected via air transmission to a transducer, the overamplification in the underdamped systems varied between 2-4 and 4-3, and in the capillary-damped systems between 1-1 and 1-2. The capillary damping gave an approximately linear relation between phase shift and frequency in the high frequency range with a calculated delay of about 4ms. The low frequency time constant in the systems varied between 1-9 and 4-6 s, depending on the amplifier setting used, which for sine curves of frequency 0-5 and 2 Hz means an apparent prematurity for their maxima and minima varying between 53 and 1 ms, this being larger with lower frequency time constants and lower frequency curves.

Amplifiers, Electronic↗
PubMed1979

The reaction of solvated electrons with cytosine, 5-methyl cytosine and 2'-deoxycytidine in squeous solution. The reaction of the electron adduct intermediates with water, p-nitroacetophenone and oxygen. A pulse spectroscopic and pulse conductometric study.

Using conductivity detection, pulse radiolysis experiments showed that solvent protonation of the electron adducts of cytosine, 5-methyl cytosine and 2'-deoxycytidine occurs with rate constants k greater than or equal to 2 x 10(4) M-1S-1. The protonated electron adducts transfer an electron to p-nitroactetophenone (PNAP) with rate constants ranging from 3.5 x 10(9) to 5.3 x 10(9) M-1S-1. The transfer is quantitative (G = 2.7), as shown by conductometric and spectroscopic measurements. In the presence of O2 no electron transfer to O2 takes place, implying that O2 adds to the protonated electron adduct radicals. No electron transfer from the H- and OH-adducts of the cytosine derivatives, either to PNAP or to O2, takes place near neutral pH. It is suggested that the differences in the reaction behaviour of the H-adduct radicals and the protonated electron adduct radicals towards PNAP can be accounted for if different radicals are formed by H-addition and protonation of the electron adduct. The H atoms most probably add to the C-5-C-6 double bonds, whereas the electron adducts are protonated at N-3 and/or 0-2.

Acetophenones↗
PubMed1978

To pulse or not to pulse.

Pulsatile and nonpulsatile blood flow have been intensely studied for cardiopulmonary bypass (CPB), isolated organ perfusion, and myocardial preservation. Although early studies differed, later ones have shown the benefits of pulsatile flow. Kidney function, lymph flow, and oxygen consumption are increased during pulsatile perfusion. Also, nonpulsatile CPB increases total peripheral resistance and mean arterial pressure, which are related to time of perfusion. Theories to account for the superiority of pulsatile flow include: (1) "vascular shocks" causing physical displacement of tissues, which changes the boundary layer of interstitial fluid around cell membranes and enhances diffusion ;(2) increased lymph movement during pulsatile flow; and (3) pulsatile energy ensuring the patency of the vascular beds and preventing shunting. New methods to create pulsatile flow and their adaptation to the standard roller pump are discussed.

Animals↗