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Biomedical subjects

K Hampl

Publications and source records attributed to K Hampl.

10 recordsLinked to original sources
PubMed1999

Mechanism of antinociceptive action of clonidine in nonmyelinated nerve fibres.

Despite a large body of clinical evidence in favour of a local anesthetic effect of clonidine, the underlying mechanism has not yet been elucidated. In this study we have used the sucrose-gap method to measure the effects of clonidine on the electrophysiological properties of nonmyelinated nerve fibers in the rabbit vagus nerve. The results showed that clonidine enhanced the hyperpolarizing and reduced the depolarizing afterpotential that follow compound action potentials during electrical activity. We showed that summation of these afterpotentials shifts the membrane potential toward more negative values, thus creating a region of low safety conduction, where the local circuit currents might fail to depolarize the axonal membrane to the threshold value needed to open voltage-dependent Na(+) channels. Yohimbine did not reverse the inhibitory effects of clonidine on impulse propagation, indicating that the observed effects of clonidine relies on mechanisms not mediated by alpha(2)-adrenoceptors.

Action Potentials↗
PubMed1994

Allergic contact dermatitis from ethyl chloride and sensitization to dichlorodifluoromethane (CFC 12).

Despite the widespread use of ethyl chloride as a local anesthetic and chlorofluorocarbons as propellants in medical and cosmetic aerosols, contact allergy to these 2 gases is rare. In a 30-year-old woman, an unusual itchy dermatitis appeared at all skin sites where a medical aerosol containing ethyl chloride had been briefly applied. Subsequent re-exposure to the spray and patch tests revealed contact sensitization to ethyl chloride and dichlorodifluoromethane (CFC 12). Histologic and immunohistochemical examinations of the test reaction were consistent with a T-cell-mediated allergic reaction. The low incidence of contact allergy to ethyl chloride and chlorofluorocarbons may be due to the rapid evaporation of these volatile gases, thus preventing intense and prolonged contact with the skin and consequently contact sensitization. A modified patch test procedure using perforated plastic chambers to allow gas evaporation is necessary to test volatile agents.

Adult↗
PubMed1988

[Normal values in rhinomanometry].

Despite various methods of investigation, there are few reports as to the normal values of nasal airway resistance. A total of 56 adult subjects free of any nasal disease underwent nasal airway resistance measurement using active anterior rhinomanometry according to the guidelines of the international committee on standardization of rhinomanometry. Inspiratory and expiratory resistance was measured before and after application of a topical decongestant spray. This test was reproducible in that 46 of the subjects underwent a second study with resistance values quite close to that of the initial measurement. The upper range of the total inspiratory nasal airway resistance was 0.45 Pa s/cm3 before and 0.3 Pa s/cm3 after decongestant administration. There was no statistically significant difference between the inspiratory and expiratory resistance measurements. No correlation could be made between nasal airway resistance, age, sex, height or weight.

Adult↗
PubMed1988

[Clinical comparison of 2 modern rhinomanometers].

Two rhinomanometers (the NR 6 manufactured by Mercury, Scotland and the Rhino-Comp manufactured by Cintec, Sweden) were tested and compared in five subjects. Both instruments are suitable for clinical use and produced equal measurements of nasal airway resistance. The Rhino-Comp device is easier to handle. Technical improvements would be desirable in both machines.

Airway Resistance↗