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Biomedical subjects

K E Bucher

Publications and source records attributed to K E Bucher.

11 recordsLinked to original sources
PubMed1982

The quantitative assessment of topical irritancy and its application to unphysiological pH-values.

Injection of aqueous solutions of topically irritant substances intracutaneously into the skin of juvenile white mice creates a persisting oedema which can be assessed by the number of wrinkles formed upon reefing the skin at the site of injection. An algorithm is presented which transforms the number of wrinkles recorded just before as well as 2.5 h and 6 h after injection into the intensity of the oedematous reaction. The results obtained with a collective of about 10 mice per solution to be tested are reliable and reproducible; they conform to dose-response relations and hence can serve for quantifying local irritancy. The method is used to investigate the effect of pH, and a general model is developed describing the local irritancy of unphysiological pH-values.

Animals↗
PubMed1981

Kybernetics of cardio-respiratory synchrony: characterization by modulating cardiac frequency.

The work concerns the special and particularly efficient kybernetic system which synchronizes respiratory and cardiac activities in rabbits. An experimental procedure is worked out to characterize its potentialities. It consists of an artificial, elective and continuous slowing down of cardiac frequency in left-side vagotomized animals. Whenever synchrony happens to exist - and this can be provided - such slowing down will tend to throw the two rhythms out of phase. The stronger the kybernetic system, then the more it should be able to outweigh such disturbing tendencies. The correlation between the speed of cardiac slowing and the number of synchronized breaths resisting such disturbances follows a hyperbolic course. Characteristics of this hyperbola offer a useful means of quantifying the kybernetic system.

Animals↗
PubMed1981

The topically irritant substance: essentials - bio-tests - predictions.

The paper describes a method for judging the irritative potentialities of substances; proposes a scoring system with which the 'ordinary' risks of many of the abundant marketed products for washing, cleaning etc. may be predicted without biological testing; discusses pharmacodynamic and pharmacokinetic aspects of topical irritancy and points to the problems of extrapolating from animal experiments to man.

Animals↗
PubMed1979

Irritant actions of unphysiological pH values. A controlled procedure to test for topical irritancy.

The abdominal skin of juvenile white mice was used. Topical application was accomplished by intracutaneous injection. The solutions tested were thoroughly standardized. By using a special buffer system, a mixture of histidine glutamate and lysine glutamate, each pH value could be tested with the same buffer capacity. The pH values varied from pH 3 to pH 11, the solutions being always iso-osmolalic with plasma. Two criteria were used to judge the irritancy: (a) the edematous reaction for the first 6 h and (b) the macroscopic aspect after 24 h. A very special procedure enabled us to obtain objective numerical values for criterion (a). The results disclose that irritation becomes manifest at pH 4 and pH 10, becomes clear-cut with pH 3 and even more so with pH 11, and depends strongly on the buffer capacity employed. With two substances-amidosulfuric acid and (tri) sodium phosphate--it was exemplified how the procedure could be used to routinely screen for topical irritancy in an informative, inexpensive and decent manner.

Animals↗
PubMed1977

Cardio-respiratory synchronisms: synchrony with artificial circulation.

Rabbits with an artificial cerebral circulation can synchronize their respiratory rhythm with the pump stroke. There is evidence that the responsible kybernetic system is of a very elementary nature. The efficacy of the system is considerable and the experimental set-up as a whole offers itself as a model to search for drugs to increase the synchronizing potentialities.

Animals↗
PubMed1977

Quantifying drugs influence on cardio-respiratory synchronism.

The paper concerns the situation in which, for a considerable time, the onset of each respiratory cycle coincides with one and the same section of a cardiac cycle. A standardized procedure is described with which, in anesthetized rabbits, the potentiality of the biological mechanisms responsible for the phenomenon may be quantified. The procedure consists of progressively prolonging the cardiac cycles by selectively cooling the sinus node. Care is taken that during such procedure a situation is passed in which the respiratory cycles are a multiple of the cardiac cycles. The synchronizing kybernetic system, if any, must click in, then. As the prolonging of the cardiac cycles continues, the synchrony will get lost the sooner the weaker the potentialities of the kybernetic system and vice versa. Four drugs are tested as to their potential action on the kybernetic system. Nikethamide and methylphenidate tend to decrease its efficacy, allobarbital and benzoctamine tend to increase it, none of them, however, being conclusively effective.

Animals↗
PubMed1977

Cardio-respiratory synchronisms: synchrony with artificial circulation.

Rabbits with an artificial cerebral circulation can synchronize their respiratory rhythm with the pump stroke. There is evidence that the responsible kypernetic system is of a very elementary nature. The efficacy of the system is considerable and the experimental set-up as a whole offers itself as a model to search for drugs to increase the synchronizing potentialities.

Adaptation, Physiological↗