Influence of the growth retardant tetcyclacis on cell division and cell elongation in plants and cell cultures of sunflower, soybean, and maize.

Taking tetcyclacis, a norbornenodiazentine derivative, as an example, the influence of a growth retardant on the shoot growth of sunflower, soybean, and maize seedlings grown and treated in hydroculture was investigated. In detail, the reduction in the length of various shoot sections {epicotyl, 1st internode, leaf blade) caused by the retardant was studied. At low concentrations of the retardant (\lt10(-6) M) the shortening effects are substantially attributable to an influence on cell elongation, whereas cell division is inhibited as the concentration increases (τ10(-6) M). A comparison of the effects of tetcyclacis in cell suspension cultures of appropriate plant species showed that also in this system concentrations τ 10(-6) M inhibited cell division growth, i. e. there is comparability of plant/ cell culture regarding the retardant effect on cell division. In contrast to the intact plants, however, cell elongation appears to be of only subordinate importance for the growth of cell cultures, as it has been shown using parsley cell suspension cultures. It is discussed to what extent influencing the gibberellin or sterol biosynthesis by means of tetcyclacis provides an explanation for the concentration-dependent effect on the cell division and cell elongation processes.

Increased incidence of side effects after encainide: a newly developed antiarrhythmic drug.

In a clinical trial the efficacy of encainide, a newly developed class I antiarrhythmic agent, was compared with the well-known mexiletine. Nine patients with different underlying cardiac disease and chronic complex ventricular ectopies (documented by 24-h Holter monitoring, confirmed during the initial placebo period) entered the study. The dosage of encainide was increased from 25 to 75 mg three times daily and the antiarrhythmic effect monitored by repeated 24-h Holter registration and in some patients by treadmill exercise testing. During the clinical followup we noted a high incidence of so-called "minor side effects" (headache, dizziness, blurred vision, tremor, and nausea), which caused us to terminate the study. In all instances adverse effects emerged before ectopic activity was suppressed satisfactorily prohibiting further increment of dosage. These results indicate that encainide cannot be regarded as an antiarrhythmic drug of first choice in routine clinical application.

Quantitative distribution of locally applied lindane in human skin and subcutaneous fat in vitro. Dependence of penetration on the applied concentration, skin state, duration of action and nature and time of washing.

Commercial concentrations of radiolabelled lindane emulsion were applied to human skin specimens. Penetration of the substance into the different layers of the skin was examined quantitatively under the common conditions of therapy, but with variation of the period of action (3, 10 and 24 h), condition of skin specimens (intact, stripped), concentration of the emulsion applied (0.3 and 1%) and washing with water only or water and soap after different periods of action (3 and 10 h) and examination at different times after the washing procedure (7 and 14 h). The flux of lindane in the skin was found to be time-dependent. Generally, the concentration increased with the depth of the layer. An increased availability of lindane (in absence of the stratum corneum, and at long application period) resulted in a preferential accumulation in the epidermis and not in the subcutaneous fat. When the intact skin had been washed with soap and water 3 h after application, the concentration of lindane found in the layer below the stratum corneum 7 h later was higher than the one found when the skin had not been washed. When intact skin had been washed after a short penetration period (3 h), this resulted in an introduction of lindane by the washing process. This effect did not occur with stripped skin. Lindane could be more efficiently removed from the stratum corneum with soap and water than with water alone. A threefold increase of the lindane concentration applied resulted in a threefold increase of the concentration in all layers of intact skin specimens. In stripped skin specimens, an increase could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Q-T prolongation and torsades de pointes in a patient with subarachnoid hemorrhage.

An extreme Q-T prolongation in a patient with subarachnoid hemorrhage was observed. Multiple torsades de pointes occurred. Lidocaine, metoprolol, and atropine were not effective in controlling the arrhythmia, whereas shortening the Q-T interval by intravenous administration of orciprenaline or overdrive ventricular pacing was successful. The occurrence of T wave alternations was a sign of increased sympathetic activity.