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Biomedical subjects

W K Barnikol

Publications and source records attributed to W K Barnikol.

At least 37 records · Page 2Linked to original sources
PubMed1990

Measurement of phase I volume breath by breath in spontaneously breathing guinea pigs.

A new method to determine phase I volume in tracheotomized spontaneously breathing guinea pigs is presented. Measurements were performed in three animals weighing 567-896 g. In simultaneous tracings of tidal volume (VT) and expiratory profiles of endogenous gases (PO2 or PCO2), the phase I volume of each breath was determined graphically as the volume expired up to the end of phase I of the expirogram. The mean phase I volume of different animals ranged from 0.29 to 0.43 ml with an arithmetic dispersion between 0.014 and 0.021 ml. Spontaneous sighs sometimes with doubling of the VT caused a significant rise of phase I volume up to 50% of the normal values. The linear regression curve was calculated for corresponding VT's and phase I volumes. The VT gradient of the phase I volume as the slope of this curve ranged from 0.108 to 0.217 ml/ml VT. The results of the new procedure, which works also with humans and rabbits, are discussed in respect to improvement of the characterization of the bronchial system. Compared with the human system, the VT gradient of the guinea pig is four times greater. By not being affected by disorders in pulmonary gas exchange, the phase I volume determined as described is a new suitable quantity to specifically assess actions and reactions of the bronchial system.

Animals↗
PubMed1989

Low viscosity of densely and highly polymerized human hemoglobin in aqueous solution--the problem of stability.

The viscosity of highly and densely polymerized human hemoglobin is low enough in reasonable concentrations to serve as an effective oxygen carrying blood substitute. But polymerisation with glutardialdehyde leads to instable polymers. In contrast polymerisation with diisocyanate gives stable polymers which can be fractionated. Fractionation reduces viscosity. The viscosity of the fractionated polymers is at 5 g/dl as low as the viscosity of plasma.

Cross-Linking Reagents↗
PubMed1989

[Temperature, pH value, acid load and filtrability of normal human erythrocytes: in vitro studies--possible significance for hyperthermic hyperacidotic tumor therapy].

Normal human red blood cells, taken from healthy young men were separated from the other blood cells with the aid of a density centrifugation. The cells were titrated with acid to a defined minimal pH value and retitrated with sodium hydroxide to normal pH (7.4 +/- 0.1) two times. After each of the two acid loadings, which were done at 37 degrees C (normothermia) and 43 degrees C (hyperthermia) the so-called specific filtration time (FZsp) is determined with 5 microns Nuclepore membranes under 4% hematocrit. FZsp is a measure for the relative flow resistance of the red blood cells they have with the filtering membrane. FZsp was found to be irreversibly increased by the twofold acid load. The effect increases with decreasing pH and increasing temperature. Hydrochloric acid has a greater effect than lactic acid.

Acid-Base Equilibrium↗
PubMed1982

Dependence of visible spectrum [epsilon (lambda)] of fully oxygenated hemoglobin on concentration of hemoglobin.

Lambert-Beer's law assumes that the extinction coefficient of a dye is not influenced by its concentration. Some experiments of Barnikol (Proc. Int. Congr. Physiol. Sci. 27th Paris 1977; Respiration 36: 86-95, 1978) led to the presumption that especially at highly concentrated hemoglobin (Hb) solutions Lambert-Beer's law does not hold. To further elucidate this problem we have measured the extinction coefficient of completely oxygenated hemoglobin (epsilon HbO2) over a wide range of Hb concentrations (CHbO2). Our results prove clearly that epsilon HbO2 in visible range as well as in the Soret region depends on CHbO2. In our opinion the invalidity of Lambert-Beer's law is caused by the self-association of the Hb molecules. This concept is a powerful tool to explain the high n values (n greater than 4) which were obtained by some authors in animal blood (bird, frog, trout, earthworm). Furthermore the influence of the self-association on the physicochemical properties of concentrated solutions of human hemoglobin is discussed.

Chemical Phenomena↗
PubMed1982

[The broncholytic effect of buffers applied by inhalation. A new pharmacological concept (author's transl)].

A new method was developed by which the tone of bronchial smooth muscle can be measured breath by breath in man. Thereby state and reactions of bronchial smooth muscle can be studied. Former investigations had shown that carbonic anhydrase inhibitors have a broncholytic effect. The mechanism of action presumably is the prevention by carbonic anhydrase inhibitors of CO2 induced changes of pH within the bronchial epithelium occurring breath by breath with different partial pressures of CO2. Principally a stabilisation of pH can also be achieved by buffers. Therefore the broncholytic effect of buffers was tested and a 10% buffer solution of phosphat and Tris (THAM) buffer applied by inhalation in two healthy volunteers. In both cases a significant bronchodilation was seen, which in case of phosphate was substantially greater than in case of conventional broncholytics (e.g., fenoterol). As concerns onset and duration of the broncholytic effect, buffers are similar to conventional broncholytics. It is great advantage that buffers do not stimulate bronchial peristalsis and do not have cardiac side effects, contrary to conventional broncholytics.

Adult↗
PubMed1980

[Dependence of the anatomical dead space on the tidal volume and on the endexpiratory lung volume: dynamic behaviour and stabilization of the bronchiolar tone (author's transl)].

The anatomical dead space was measured in dependence on the tidal volume and on the endexpiratory lung volume (respiratory level). A new method, the method of dead air plateau, was employed. The dead space increases with tidal volume (4 ml/100 ml). It is not dependent on the respiratory level. This was also directly shown in breathing manoeuvres changing the respiratory level rectangularly. In such manoeuvres a stabilization process can be seen. The same results give resistance measurements (oscillatory method). Values are taken in the endinspiratory state. This corresponds to the dead space volume. The 70% time of the stabilization reaction can be estimated, it is 20 sec. Taking this time into account, it is well understood that dead space volume is dependent on the tidal volume, but not dependent on the respiratory level. This time also makes evident that the often mentioned history of lung parameters lasts approximately 20 sec. The biological significance of the stabilization is discussed.

Bronchi↗
PubMed1980

[Two new characteristic quantities for characterization of the bronchial state in vivo and of pharmacological effects. The discordant behaviour of the bronchial system (author's transl)].

The classical quantity to characterize the state of the human bronchial system is the airway resistance (Raw). We have developed a new method for measuring the anatomical dead space (VD) and we have shown that the bronchial system may be characterized by the anatomical VD as well. Both Raw and VD are taken as mean values. In systematic investigations with our new VD method we found two facts: (1) under certain conditions VD depends unequivocally on the tidal volume (VT), the socalled VT gradient, and (2) VD varies periodically (bronchial peristalsis). The same is valid for Raw. From these observations one can derive two new characteristic quantities for the human bronchial system: (1) the standard deviation of the oscillations (sigma) as a measure of the bronchial motility and (2) the VT gradient as a measure of the bronchial compliance. With the aid of the two new characteristic quantities two types of bronchial reactions are defined: the concordant and the discordant reaction. Concordant means: VD increases (Raw decreases, respectively), sigma decreases, and the absolute value of the VT gradient increases or all effects are inverted. Discordant means: deviations from the concordant behaviour. All given examples but one show a discordant reaction. The new characteristic quantities improve the possibility to discriminate bronchial reactions, e.g., on drugs. The discordant behaviour is an expression for the complexity of the bronchial system.

Airway Resistance↗
PubMed1979

[The broncholytic effect of carboanhydrase inhibitors in subjects with healthy lungs (author's transl)].

Carboanhydrase inhibitors are said to have a positive effect on respiratory insufficiency. We examined this, especially regarding the bronchial system. Actions and reactions of the human bronchial system can be followed by measurement of the anatomical dead space breath by breath. We have developed a new method which was tested by classical broncho-effective substances. Our experiments show in case of two men with healthy lungs that the three carboanhydrase inhibitors acetazolamide, methazolamide, and dichlorphenamide have a pronounced broncholytic effect. The effect is greater than that of fenoterol. In addition the bronchial peristalsis and the bronchial compliance are increased. In contrast to fenoterol carboanhydrase inhibitors have no cardiac side effect.

Acetazolamide↗
PubMed1978

[Polarographic measurements of PO2 with a 95% response time of 7-10 msec (author's transl)].

A fast PO2 tracing with 95% delay times of 15-20 msec in routine is necessary for measurement of the PO2 jumps in the expired air, particularly for the precise measurement of the so-called dead-air plateau. A Clark type PO2 electrode has been developed which has the demanded property. This electrode has four characteristic features: (1) a glasscoated Pt cathode with a tip diameter of 0.3 mm (diameter of the Pt wire = 0.1 mm); (2) a differential screwdrive for feeding the cathode 50 micrometer per turn; (3) a 0.2- to 0.3-micrometer-thin polytetrafluorethylene membrane, and (4) a special polishment of the surface of the cathode. The electrode has a 95% response time of 15-20 msec in routine when tracing PO2 changes from 150 to 750 mm Hg. About 30% of the prepared electrodes have response times of 7-10 msec. The output of the electrode in air is stable within the first 3 h (deviation smaller than 0.2%) and then decreases within 10 h approximately 1% per hour. The response times are constant for more than 48 h. The output of the electrode is linear from 0 to 760 mm Hg PO2. Within the accuracy of measurement the output is independent of PCO2.

Electrodes↗