Signal-averaged ECG in patients with antidepressant therapy.

The signal-averaged electrocardiography (SAECG) identifies patients at risk of ventricular arrhythmias and sudden cardiac death. Since the similarity has been known of the pharmacology of class I antiarrhythmics and tricyclic antidepressants, the potential proarrhythmic effects of antidepressants has become a particular problem. The influence of sodium channel blocking antidepressant drugs on the SAECG time-domain parameters was evaluated, using high-pass filters of 25 Hz and 40 Hz. SAECG was performed in 11 depressed patients with normal cardiac status before and for 4 weeks after antidepressant initiation. At the filter setting of 25 Hz, a significant worsening of all studied SAECG parameters (filtered QRS duration, low-amplitude signal duration, root mean square voltage in the first and in the last 40 ms of the filtered QRS) was found in our patient group. Using a 40 Hz high-pass filter, the results were similar. Antidepressant therapy significantly prolonged filtered QRS duration, significantly reduced root mean square voltages in the first and in the last 40 ms of the filtered QRS and non-significantly prolonged low amplitude signal duration. Amitriptyline and maprotiline induced late potentials (LP) in 2 patients at 40 Hz high pass filter setting. No patient had LP at 25-250 Hz. Our pilot study indicates that sodium channel blocking antidepressant drugs may affect SAECG variables similarly to class I antiarrhythmics. SAECG might be useful in categorizing of antidepressant agents and risk stratification of psychiatric patients.

[EPR spin trapping of reactive oxygen products of the respiratory burst of phagocytes (use of EPR spectroscopy in biology and medicine. II)]. / Spin trapping EPR stúdium reaktívnych kyslíkových produktov respiracného vzplanutia fagocytov (vyuzitie EPR-spektroskopie v biológii a v medicíne II.)

Respiratory burst during phagocytosis of human neutrophils is connected with the production of superoxide anion radical O2.-. This radical changes into further bioreactive oxygen products (especially H2O2 and .OH) which can be harmful to the organism. The principles of EPR spin trapping, the most reliable method for the study of short living free radicals, are presented. Advantages and problems of the study of O2.- and .OH by means of the 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin trap were assessed. Overproduction of O2.- (e.g. by chronic inflammation) can be treated with superoxide dismutase (SOD) or other drugs with SOD-like activity. Methods for studying such superoxide scavengers are reviewed. (Fig. 3, Tab. 2, Ref. 88.).

[Use of electron paramagnetic resonance spectroscopy spin labels in studying the properties of biological membranes]. / Vyuzitie spektroskopie EPR spinových znaciek pri stúdiu vlastností biologických membrán.

Electron paramagnetic resonance (EPR) spectroscopy of spin labels has become a widely spread method in biochemistry, molecular biology, and medicine. After a brief view on the structure and functions of biological membranes, basic principles of EPR and particularly of the spin labeling technique are presented. Applications of this technique are demonstrated on the study of various properties of biological membranes, such as phase transition of lipids, properties of different membrane parts, permeability of membranes, inner volumes of liposomes and cells, membrane potentials, lateral diffusion, lipid-protein interaction, and determination of oxygen concentration. As an example the results of a study concerning the effect of chlorpromazine and its derivatives on the dynamics and lipid-protein interaction in synaptosomes are presented.