Biomedical subjects
W Grabowski
Publications and source records attributed to W Grabowski.
[Organizational structure of hospitals for the poor in the Duchy of Lowicz in old Poland].
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The transmission and interpretation of emergency department radiographs.
Twenty-five radiographic studies representative of the spectrum of trauma cases that might present to an emergency department were selected from actual cases presenting at Brooke Army Medical Center (BAMC) in San Antonio, Texas. The studies were then transmitted from a local television studio via satellite back to BAMC and three other Army hospitals. A panel of 29 physicians (11 radiologists, 7 emergency physicians, and 11 others from various specialty areas) viewed the images on commercial grade television sets and attempted to make a diagnosis. The diagnostic accuracy of the radiologists (86%) was significantly better than that of the other two groups (77% each). However, given the overall expense of a teleradiology network, this difference in accuracy - especially when translated into clinically significant errors - might not justify the establishment of such a network in terms of cost-effectiveness.
Interpretation of radiographic images transmitted via satellite.
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Analysis of faeces for benzo[a]pyrene after consumption of charcoal-broiled beef by rats and humans.
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The effects of isoprenaline and a new beta-sympathomimetic amine upon spontaneous activity, diastolic depolarization and plateau height in cardiac Purkinje fibres.
1 In spontaneously active Purkinje fibres of young cows the dose-response curves of the action of isoprenaline upon different electrophysiological parameters were measured.2 The increase in slope of diastolic depolarization could roughly be described by a one-for-one binding curve with a half maximum effect near 10(-8) M and the increase in the height of the plateau level by a two-for-one binding curve with a half maximum effect near 10(-7) M (-)-isoprenaline.3 These dose-response curves were similar to those of two parameters measured under voltage clamp conditions by other authors. The increase in slope of diastolic depolarization behaved like the shift of the activation curve for the pacemaker potassium current towards positive potentials and the growth in plateau height like the increase in the slow inward current mainly carried by Ca ions. From this conformity we propose that the parameters evaluated by us from action potential records could be used for a qualitative analysis of the action of catecholamines on pacemaker potassium current and Ca influx.4 The effects of the isomers of a new drug, 1-isopropylamino-3(4'hydroxyphenoxy)-propan-2-ol (IHP), were evaluated in the same way as those of isoprenaline. The (-)-isomer was at optimal concentrations (10(-5) M) nearly half as effective as isoprenaline in increasing frequency and slope of diastolic depolarization but caused no increase in plateau height. An identical relationship, but at 5 to 10 times higher concentrations, was obtained with the (+)-isomer.5 When 10(-4) M(-)-IHP was added to a preparation equilibrated with a maximum dose of (-)-isoprenaline (10(-6) M), frequency and plateau height declined. This result together with the observation that the effects of IHP could be blocked by the specific beta-antagonist propranolol, revealed the beta-agonistic nature of the new drug. Its inefficiency in increasing the plateau height and thus the slow (Ca) inward current was explained by its relatively low potency and intrinsic activity.
Activation of the electrogenic sodium pump in guinea-pig atria by external potassium ions.
1. When cardiac preparations are rewarmed following prolonged hypothermia a transient hyperpolarization occurs in K-containing media. This hyperpolarization is correlated with the active Na efflux. It might be due to electrogenic Na pumping or to extracellular K depletion brought about by the activity of an electroneutral Na-K exchange pump. In order to distinguish between these mechanisms the effect of various extracellular K concentrations ([K](o)) on the membrane potential of guineapig atria was studied before and after hypothermia.2. The membrane potential increased with decreasing [K](o) before cooling. It reached values of -64 and -92 mV at 10.8 and 0 mM-K, respectively.3. The membrane hyperpolarized transiently after hypothermia beyong the potential observed before cooling. Maximal values of about -94 mV were obtained during rewarming in solutions containing 0.4-2.7 mM-K. The membrane potential was significantly lower (-88 mV) in K-free media. It was also diminished at [K](o) higher than 2.7 mM and was measured to be -74 mV at 10.8 mM-K.4. The hyperpolarization of the cell membrane during the first 20 min of rewarming was maximal at 2.7 mM-K and yielded 15.5 mV. The hyperpolarization amounted to 7.2 and 10 mV at 0.4 and 10.8 mM-K, respectively. No hyperpolarization occurred in K-free solutions.5. The rate of decline of the transient hyperpolarization increased with [K](o).6. Variations of membrane input resistance after changes in [K](o) were measured in rewarmed atrial trabecula. The measurements revealed an increase in membrane resistance in lower [K](o).7. It is concluded that the transient hyperpolarization of the cardiac cell membrane during rewarming is due to the activation of an electrogenic Na pump.8. The (relative) strength of the pump current at various [K](o) was derived from the observed dependence of the hyperpolarization and of the membrane input resistance on [K](o). The current is estimated to be half-maximal at about 1.5 mM-K.
The effect of repetitive stimulation at low frequencies upon the electrical and mechanical activity of single muscle fibres.
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[Crossed dislocation of a single kidney].
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