[Clinical significance of stress reactivity for frequency of electric shock discharges in patients with implanted cardioverter-defibrillators]. / Klinische Bedeutung von Stressreaktivität für die Häufigkeit von Schockabgaben bei Patienten mit implantiertem Kardioverter-Defibrillator.

BACKGROUND AND OBJECTIVE: Recent research indicates that discharges of implanted cardioverter-defibrillators (ICD) are triggered by psychosocial stress. This study examined the presence of patterns of psychophysiological stress reactivity in ICD-patients. Further more potential relationship between factors of stress reactivity and the frequency of implantable cardioverter-defibrillators discharges was investigated. PATIENTS AND METHODS: In 46 consecutive patients (38 male, 8 female; age: 26-80 years) with implantable cardioverter-defibrillators the following parameters of physiological reactivity were measured in a standardised experimental stress test: Heart rate, skin conductance, muscle tension and respiratory activity. In a standardised interview anxiety sensitivity, depression, desire for control, stress load, and attitude towards the defibrillator were evaluated and quantified. The relationship between the mentioned parameters were examined with factor analysis to reveal patterns of psychophysiological reactivity. Potential relationship between psychophysiological factors and frequency of shock delivery was verified with linear regression analysis. RESULTS: Factor analysis revealed four independent psychophysiological traits. The factors were named "Play Dead Reflex", "Heart Phobia", "Negativism" and "Irritability". Linear regression model showed significant correlation between "Play Dead Reflex" and discharge frequency. CONCLUSIONS: Results confirm the presence of specific psychophysiological stress reaction patterns in ICD-patients. The stress reaction pattern "Play Dead Reflex" could be discussed as a potential risk factor in developing life-threatening tachyarrhythmias leading to an increase in defibrillator discharges in patients with ICD. This hypothesis should be considered in prospective studies and psychosomatic treatment of concerned patients.

Association of the HNK-1 epitope with 5'-nucleotidase from Torpedo marmorata (electric ray) electric organ.

5'-Nucleotidase isolated from the electric organ of the electric ray (Torpedo marmorata) has a molecular mass of 62 kDa and, on two-dimensional electrophoresis, separates into up to 13 isoforms within a pI range of 5.9-6.7. The N-terminal sequence data show a 71% identity over 17 amino acids with that previously published for the rat liver enzyme. All forms of 5'-nucleotidase are recognized by the HNK-1 monoclonal antibody. HNK-1 immunoreactivity is found at the surface of the Schwann-cell processes covering the synaptic terminals and in this respect corresponds to that of 5'-nucleotidase in the same tissue. Since a number of glycoproteins involved in cell recognition and cell adhesion carry the HNK-1 epitope, 5'-nucleotidase may play a role in cell-cell or cell-extracellular matrix interaction in addition to its activity as an enzyme.