Neurophysiological investigation of the central nervous action of the hypnotic agent etomidate in cats (author's transl)]

1. The action of etomidate (0.125-4.0 mg/kg) injected intravenously or into the right atrium (time of injection about 1 sec) was investigated in cats under different central nervous conditions. 2. In decerebrate unanaesthetized animals and in lightly anaesthetized (pentobarbitone) animals with an intact CNS etomidate (0.25-4 mg/kg i.v.) caused a decrease of the spontaneous lumbar fusimotor activity and a strong depression of the fusimotor pinnareflex. Partly a reversal of this reflex from excitation to inhibition was observed. The effects occurred within 20 sec after the injection and lasted for 5-70 min, showing a clear non-linear relationship with the injected dose. 3. In encephale isole preparations etomidate (0.125-1 mg/kg injected intra-right atrially) caused distinct changes of the spontaneous EEB (decrease of frequency, increase of amplitude, occurrence of steeper waves) and a depression of the arousal reactions in the EEB following different stimuli (acoustic stimuli and different stimuli in the area of the face and eyes). These effects occurred within 8 sec after the injection and lasted up to 40 min, dependent upon the injected dose. 4. The character and the principal similarity of the results observed in decerebrate animals and in animals with intact CNS suggest that a considerable part of the action of etomidate consists of a depression of the activity and reactivity of the brain stem reticular formation.     

Mechanism of 201Tl uptake in tumours

We have studied the mechanism of tumour uptake of ²⁰¹Tl by in vivo and in vitro studies. In a series of patients with breast cancer (n=26), lung cancer (n=56) and lymphoma (n=15), the time course of tumour uptake of ²⁰¹Tl paralleled that in the myocardium with almost identical times of peak uptake being obtained in tumours and myocardium. In a patient with hepatic metastases from colonic cancer undergoing laparotomy, ^99mTc labelled microspheres and ²⁰¹Tl were injected into the hepatic artery and biopsies of metastatic and normal liver tissue obtained. The tumour to normal liver activity ratios for ²⁰¹Tl were one tenth of those for ^99mTc microspheres. In the final part of the study, cells from a lung cancer tissue culture line were incubated for 30 min with ²⁰¹Tl with and without the addition of cardiac glycoside, which acts a sodium potassium pump blocker. The cells exposed to the cardiac glycoside showed markedly decreased uptake of ²⁰¹Tl compared to the cells not so exposed (0.6%±0.1% vs 11.8±0.7.2% of the administered dose). The mechanism of ²⁰¹Tl uptake of tumours is similar to that in the myocardium. Sodium potassium pump activity appears to be more important than tumour blood flow. ²⁰¹Tl uptake may provide a useful means of studying tumour viability.     

One-step separation of the components of Semliki Forest virus by cation exchange chromatography

Although several procedures for isolating viral proteins have been described, the simultaneous separation of all the viral macromolecules in a single step has not yet been reported. We now describe TUA (Triton X-100, urea, acetic acid, pH 4.2)-SP (Sulphopropyl)-Trisacryl cation exchange chromatography, which proved to be ideal for this purpose. Optimal conditions for chromatography were established by screening on TUA-PAGE (polyacrylamide gel electrophoresis) using a horizontal linear 0-8.5 M urea gradient followed by identification of the proteins by SDS-PAGE in the second dimension. Segregation of the constituents of Semliki Forest virus cultivated in two cell lines (chicken embryo fibroblasts and Aedes albopictus cells) was studied, considering that the proteins have identical primary sequences but diverse post-translational modifications, thereby allowing the efficacy of the procedure and its applicability to different viruses to be tested. The results show that the RNA and lipids did not bind to the cation exchange in TUA and were eluted in the flow-through fractions. The proteins were fractionated using 3 linear NaCl gradients in TUA. SDS-PAGE revealed that all the proteins could be purified by this procedure. Furthermore, a direct correlation was obtained between the distance migrated by the proteins in the TUA-PAGE and their order of elution from the TUA-cation exchange column.