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Biomedical subjects

W Czarnecki

Publications and source records attributed to W Czarnecki.

At least 37 records · Page 2Linked to original sources
PubMed1980

Effect of clonidine on excitability and refractoriness of normal cat myocardium.

Increased activity of sympathetic nervous system enhances cardiac susceptibility to arrhythmias. Clonidine through its central action decrease sympathetic activity to the heart. The aim of this study was to investigate whether Clonidine influences excitability and refractoriness of the heart in such a way that cardiac susceptibility to arrhythmias is reduced. The effect of Clonidine (5 microgram/kg i.v.) on diastolic threshold and refractory period was investigated in the normal cat heart in situ paced at a constant rate. Clonidine increased diastolic threshold up to 63.5 +/- 24.0% (mean +/- SE) of initial value and prolonged refractory period up to 13.2 +/- 2.4% of the control throughout 120 min of observation. These data suggest that Clonidine might be of value as an antiarrhythmic agent in patients with chronic angina in whom ventricular arrhythmias are often associated with excessive sympathetic activity.

Animals↗
PubMedDate not supplied

Metabolic and haemodynamic responses to adrenaline in normal dogs.

The metabolic and haemodynamic effects of adrenaline were investigated in 6 intact anaesthetized dogs, which were subjected to an infusion of adrenaline. The dose given was similar to the endogenous production rate of adrenaline in experimental myocardial infarction. Adrenaline infusion (0.8, 1.17 ot 1.05 micrograms . kg-1 . min-1) over two hours led to a variable rise in blood level of this amine, regardless of the rate of infusion. Dogs with high blood adrenaline (over 3.5 ng . ml-1) exhibited haemodynamic deterioration, i.e. a rise in peripheral vascular resistance together with a fall in cardiac output and external cardiac work. Dogs with low blood adrenaline showed little change in peripheral vascular resistance, a rise in cardiac output and external cardiac work. The myocardial consumption of each of the substrates lactate, pyruvate, glucose and FFA was measured, and its equivalent oxygen consumption expressed as a percentage of the total myocardial oxygen consumption. No relationship was found between myocardial utilisation of individual substrates and the type of haemodynamic response. Thus in intact dogs exposed to adrenaline excess, similar to that found in acute myocardial infarction, the different types of haemodynamic response cannot be attributed to the type of substrate utilization by the myocardium, but to different rates of clearance of adrenaline. Low clearance rates lead to high blood adrenaline levels and an unfavourable response of the cardiovascular system.

Animals↗
PubMedDate not supplied

Haemodynamic effects of inosine. A new drug for failing human heart?

Haemodynamic effects of inosine were studied in intact dogs and subsequently in patients suffering from prolonged otherwise intractable cardiogenic shock. The nucleoside significantly improve myocardial performance in patients with an extremely low cardiac index by 63 +/- 29% as well as animals with no signs of haemodynamic deterioration, increasing cardiac output by 12.2 +/- 4.3%. These results suggest that inosine may become a promising inotropic agent. Further studies though are necessary to elucidate the mechanism of inosine action.

Adult↗
PubMedDate not supplied

The dissolution kinetics of sulfamethoxazol, trimethoprim and oxytetracycline hydrochloride from multicomponent solid dispersion capsules ("Sulfoxytrim").

Release profiles and dissolution kinetics of active substance, viz. sulfamethoxazol (SMO), trimethoprim (TMP), and oxytetracycline hydrochloride (OTC) from capsulated multicomponent dispersions was studied in a flow-cell apparatus at 37 degrees C by using a dissolution medium of 0.1 mol/l HCl. The results revealed that the relative dissolution efficiency (DE) and dissolution profiles of one active ingredient were affected by the presence of the two others. Vitamin C added caused the decreased the dissolution rate constants (K) and DE--values of all the active substances studied.

Anti-Bacterial Agents↗
PubMedDate not supplied

Effect of hydrophilic substances on liberation of quinidine from starch - alginate sphere.

The effect of selected hydrophilic agents on the quinidine loading and its release from potato starch alginate spheres prepared by instilling viscous suspensions into a desolvation liquid (saturated calcium chloride: paraffin liquid: heptan 1:1:1 v/v/v) was studied. The loading of quinidine in spheres was 59.77%-46.30% and it depended on the presence of auxiliary hydrophillic agents such as polyethylene glycol 2000 (59.77%), polyoxyethylene - 20 - sorbitan monostearate (49.55%), glyceryl monostearate (49.02%), sorbitan monooleate (46.30%). The drug release from spheres was diffusion controlled in accordance with the Higuchi model. It was concluded that the release rate constants depended on the drug - carrier - hydrophilic agent composition and dissolution media.

Alginates↗
PubMedDate not supplied

Dissolution of azathioprine from tablets in forced laminar flow of liquid.

The dissolution of azathioprine from tablets was investigated in a column apparatus with forced laminar liquid flow. The experiments showed that auxiliary ingredients and hydrodynamic factors affected the diffusion coefficient and solubility of the active principle and the density and viscosity of eluates from dissolution cell. For laminar flows changes in these physico-chemical parameters are described by a dimensionless equation (Formula: see text), where Sh--Sherwood number, Sc--Schmidt number, Re--Reynolds number, (Formula: see text)--grain dispersion in disintegrated tablet mass.

Azathioprine↗
PubMedDate not supplied

Factors affecting the release of papaverine from spheres.

The effect of selected carriers and auxiliary hydrophilic agents on the papaverine loading and its release from spheres prepared by instilling viscous liquids into a 1% solution of calcium chloride in ethanol was studied. The most favourable loading of papaverine in potato starch, sodium alginate and sodium carboxymethylcellulose spheres was 97.4%, 95.7% and 91% respectively, and it depended on the presence of auxiliary hydrophilic agents such as polyethylene glycol 1500, polyethylene glycol 4000, glyceryl monostearate and sorbitan tristearate (Tween 65). The drug's release from spheres was diffusion controlled in accordance with the Higuchi model for the release of 80-95% of contents. It was concluded that the release rate constants depended on the drug-carrier-hydrophilic agent composition.

Chemistry, Pharmaceutical↗