Effect of calcium channel blockers on histamine liberation from isolated basophils and bronchial reactivity in patients with bronchial asthma]

An effect of verapamil and nifedipine on the cellular histamine release and non-specific reactivity of the bronchi measured with methacholine test was studied. In vitro tests were carried out in basophils isolated from 19 asthmatic patients. Reactivity of the bronchi was investigated in 5 patients. Both verapamil and nifedipine significantly inhibited histamine release from the cells in vitro in all examined concentrations (10(-7)-10(-4) M) while a single dose of these drugs administered to the asthmatic patients did not exert a significant effect on the airway constriction in vivo.     

Role of acid proteases in brown adipose tissue atrophy caused by fasting in mice

The lysosomal proteolytic capacity of mouse brown adipose tissue (BAT) and its role during fasting were evaluated. The specific activities of acid phosphatase and cathepsins B, D, H, and L were measured in BAT of mice acclimated at 33, 21, and 4 degrees C and in BAT undergoing different rates of protein loss during a 24- to 48-h fast. The specific activities of lysosomal proteases in BAT did not vary with the acclimation status of the animals. Mice acclimated at 33 degrees C showed no significant atrophy of BAT after a fast. In mice kept at 21 degrees C, protein loss from BAT was observed after a fast without change in tissue DNA content. Protein loss from BAT was partially reduced by injection of the acidotropic agent chloroquine. Furthermore, tyrosine release from BAT during fasting was also reduced by injections of chloroquine or leupeptin, a thiol-protease inhibitor. Tyrosine release from BAT was maximum within 24 h and returned to prefast values by 36 h, suggesting rapid activation followed by inhibition of the tissue proteolytic activity. However, there was no change in acid protease specific activities, suggesting that these enzymes were not limiting for protein degradation. When cold-acclimated mice were fasted at 21 degrees C, BAT protein loss was markedly enhanced and increases in cathepsin D and L activities were observed, but there was no change in cathepsin B and H and acid phosphatase specific activities. These results indicate that BAT contains an important lysosomal proteolytic pathway that is involved in the rapid reduction of the tissue thermogenic capacity during a fast.     

Studies on microplasmodia of Physarum polycephalum

Summary Fragments excised from front regions of thinspread Physarum plasmodia were used to examine a possible correlation between the periodical dynamic activity of such specimens and the spatial organization of actin fibrils. Under isotonic conditions, symmetrical contractions and relaxations of the entire fragment alternate with a period of 1–4 min, whereas under isometric conditions local contractions and relaxations occur simultaneously in different regions of the same specimen. Rapid fixation and phalloidin-staining at distinct stages of the contraction-relaxation cycle demonstrates the permanent existence of cytoplasmic actin fibrils under both isometric and isotonic conditions. During the transition from relaxation to contraction the fibrils shorten in length from 25.5 m to 21.0 m and increase in density from 1.2 fibrils/1000 m² to 2.3 fibrils/1000 m². The present results demonstrate that actin fibrils in Physarum plasmodia are not completely decomposed and reformed every contraction-relaxation cycle.Series Studies on microplasmodia of Physarum polycephalum VIII     

Target highlights in CASP13: Experimental target structures through the eyes of their authors

The functional and biological significance of selected CASP13 targets are described by the authors of the structures. The structural biologists discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP13 experiment.