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H Hinghofer-Szalkay

Publications and source records attributed to H Hinghofer-Szalkay.

70 records · Page 4Linked to original sources
PubMed1979

[The calculation of hemoglobin concentration from blood and plasma densities, measured by the mechanical oscillator technique (author's transl)].

Blood samples from patients were taken for the measurement of blood and plasma densities by the mechanical oscillator technique, and the hematocrit value and the hemoglobin content of the blood. The values for blood and plasma density permit the precise calculation of blood hemoglobin concentration and hematocrit. Thus, in addition to the calculation of total protein concentration of plasma (Holzer et al (1978) J. Clin. Chem, Clin. Biochem. 16, 391--395), measurement of the blood density yields two further relevant parameters. In total, only 3 ml of blood are needed for the measurements.

Hematocrit↗
PubMed1978

[Determination of the serum protein concentration based on the measurement of density by the mechanical oscillator technique (author's transl)].

A linear relation is well established between the density and protein concentration of the serum. The measurement of protein concentration by a new technique for the determination of the absolute density, the mechanical oscillator technique, was investigated. The method is based on the determination of the resonant frequency of a mechanical bending-type, U-shaped glass tube oscillator filled with the sample. The shift in the resonant frequency of the oscillator caused by the mass of the defined volume of the sample taking part in the vibration can be used to calculate the density or protein concentration of the sample. In spite of the low specificity of the method, the interference of substances like glucose, urea or triglycerides is small. Simplicity and rapid results of high accuracy recommend the mechanical oscillator technique for the routine laboratory.

Blood Glucose↗
PubMed1977

The continuous high-precision measurement of the density of flowing blood.

The "mechanical oscillator" technique for the measurement of the density of fluids is based on the influence of mass on the natural frequency of a mechanical oscillator. The practical application of this principle was worked out by Kratky et al. (1969) and Leopold (1970). It is demonstrated in this study that the method permits the continuous high-precision measurement of the density of flowing blood in anesthetized animals. The accuracy is 10(5) g/ml, the maximum sampling rate 20/min. As found in rabbits and cats during the control state, physiological blood density changes related to spontaneous blood pressure variations are up to 2-10(4) g/ml. The method can be combined with i.v. injections of isotonic and iso-oncotic solutions to determine cardiac output and blood volume on the basis of a "density dilution" principle. Since the density of the interstitial fluid is lower than that of blood, fluid shifts through the capillary walls can be detected. The effects of hypertonic glucose and of hyperoncotic dextran have been examined. Changes in the density of the arterial blood appear within 10 s after i.v. injection of these fluids. Similarly, density changes result from hemorrhage and reinfusion. During and after i.v. administration of vasoactive drugs (noradrenaline, angiotensin II, acetylcholine), marked transient changes in blood density are seen which obviously reflect the effects of fluid shifts through the capillary walls. During hemorrhagic hypotension we found periodic variations in the blood density synchronous with spontaneously occurring Mayer waves. The new method seems to be a promising tool for investigations physiological and pathological capillary fluid dynamics.

Acetylcholine↗
PubMed1977

[The relation between the density of blood and the arterial pressure in animal experiments and in patients during hemodialysis (author's transl)].

The density of arterial blood was measured continuously in animals and in human beings with an accuracy of 10(-5) g/ml by the application of the so-called mechanical oscillator technique. The density measuring device is inserted into an arterio-venous shunt. The continuous reading of the density of arterial blood allows to observe the effect of fluid shifts between the interstitial space and the plasma space. For example, lowering of the capillary pressure by the constriction of the precapillary resistance decreases the blood density by the inflow of interstitial fluid. Strong vasoconstriction apparently increases the capillary pressure and thus raises the blood density by the loss of plasma-ultrafiltrate. During hemodialysis the fluid loss into the dialysator tends to increase the blood density. However, the regulatory mechanisms of the circulation are able to keep the density of the blood at a constant value as long as possible. An increase of the density indicates a decrease of the blood volume. The new method thus allows a continuous control of the course of hemodialysis, and to avoid a critical decrease of the blood volume and of the blood pressure.

Animals↗
PubMed1976

Spectral analysis of spontaneous contractions of the isolated portal vein of rats.

The spontaneous contractions of segments of rat portal veins have been examined in vitro under isotonic and isometric conditions. The power density spectra of recorded time series lasting 10-60 min were calculated. The spectra usually consist of harmonic frequency components. Only during shorter periods of analysis (10 min time series) we sometimes found additional non-harmonic components. All frequency components are proportionally shifted by changes of the bath temperature according to an average Q10 of 2.0. Increase of the load decreases the frequency of the contractons. The results of the spectral analysi, indicating a preponderance of a single source of periodicity, were supported by direct evidence of a pacemaker region. By recording contractions after systematic dissections of the portal vein segment, we found that spontaneous activity is generated at the central end of the segment.

Animals↗
PubMedDate not supplied

Determination of cardiac output and of transcapillary fluid exchange by continuous recording of blood density.

We have tested the application of the continuous measurement of the density of the arterial blood for the calculation of the cardiac output and for the determination of the transcapillary fluid exchange. The density of arterial blood was continuously recorded in anesthetized dogs with a mechanical oscillator device (DMA 602 MW built by A. Paar KG, Graz). The time resolution of this device is less than 1 sec, the accuracy is 10(-6) g/ml. Simultaneously the arterial blood temperature was recorded with a thermistor probe. The intravenous injection of isotonic solutions yields temperature and density transients which are of a similar shape and proportional to the injected volume in amplitude. There is a good agreement between the cardiac output calculated from thermodilution transients and from density dilution transients. The injection of hypertonic solutions, e.g. 5% NaCl, 20% mannit or 14.4% urea, into a vein yields arterial density dilution transients which show marked differences and very characteristic features. They can be explained by the assumption of osmotic fluid shifts in the microcirculation of the lung. During the transient of a bolus of hypertonic NaCl or mannit, a transcapillary influx of about 0.170 X 10(-3) ml/sec per mosmols/l and per g wet tissue weight is generated. The effect of hypertonic urea is less by a factor of about 1/2, which is in agreement with the fact that urea diffuses rapidly into the erythrocytes. We conclude that the method of density dilution allows to record and quantify cardiac output and osmotic fluid shifts through the microcirculation of the lung of intact dogs.

Animals↗
PubMedDate not supplied

Variations of pial arteriolar diameter, arterial blood pressure and arterial blood density in the cat.

Feline pial arteriolar diameters (CVD, cerebral vessel diameter), mean arterial blood pressure and blood density were recorded continuously in order to examine the relation between rhythmic diameter variations and oscillations of blood pressure and density. Under constant arterial pressure, blood density and CVD oscillations of 2-6/min were recorded using a photometric technique. Furthermore, pressure and density variations were induced by bleeding and reinfusion of blood, to observe their influence on CVD. The latter over a period of time become synchronized to parallel variations of pressure and density during hemorrhagic hypotension. This observance was noted after an initial lag phase.

Animals↗