Induction of histamine release and desensitization in human leukocytes. Effect of anaphylatoxin.

Hog anaphylatoxin (AT) in concentrations from 0.5 to 5 mug/ml gives a dose-dependent histamine release from human leukocytes. Concentration of 100 mug/ml AT give the same high histamine release as 5 mug/ml. This is in contrast to the histamine release obtained with anti-IgE or allergen, which give low histamine release with high doses. The histamine release obtained with AT is completed in 20 sec and the reaction is temperature- and calcium-dependent. Treatment of cells with AT in the presence or absence of calcium makes them insensitive to another challenge with AT. Such treated cells are fully responsive, however, to challenge with anti-IgE if the pretreatment has been performed in the absence of calcium. This, together with the calcium- and temperature-dependence indicates that the AT-induced histamine release is nontoxic. Treatment of cells with AT in the presence of calcium induces, besides histamine release, decrease in sensitivity to anti-IgE, indicating that both AT and anti-IgE release histamine from the same cells. We discuss to what extent AT and cell-bound Ig share intracellular mechanisms for induction of histamine release.     

The effect of external stimuli on movement of Asterias amurensis starfish]

Studies have been made on local and total motor reactions of the starfish to stimuli of different modalities. It is suggested that differences in the pattern of papillae excitation and those in total reactions to salt, mechanical stimulation and changes in the intensity of illumination are associated with structural and functional heterogeneity of receptors and afferent pathways in the lower regular layer of the nervous plexus. The ability of segment motoneurons to change the direction of tube feet movement in absence of influences from the nervous ring was demonstrated. Possible scheme of control of pedicellar movement evoked by external stimulation is discussed.     

Hyperpolarization response of an identified neuron of Planobarius corneus mollusks to several cholinomimetic substances]

Two kinds of responses to cholinomimetics were found on the identified neuron (P-2) of Planorbarius corneus pedal ganglion using microelectrode technique. Nicotinomimetics caused depolization whereas some muscarinomimetics caused hyperpolarization of the neuron membrane. Acetylcholine usually depolarized the neuron membrane but after the blockade of nicotinic receptors with tubocurarine one can reveal a hyperpolarizing action of acetylcholine. These findings suggest that two kinds of receptors exist on the P-2 neuron membrane and these receptors differ both in pharmacological characteristics and in ionic permeability changes they control.     

Models of learning based on the plastic properties of the "placing reaction" in cats]

A possibility of functional reorganization of initial sensorimotor connections of the forepaw has been shown on seven cats. The main initial relationships between the afferent tactile input and motor output for the ulnar joint of the cat forepaw are as follows: tactile stimulation of the dorsal surface of the paw produces a flexion in the ulnar joint ("placing reaction"), and that of the ventral surface, an extension of the paw in the ulnar joint ("magnetic reflex"); simultaneous tactile stimulation of the ventral surface of the paw blocks the "placing reaction" evoked by a touch of the dorsal side. Extinction was produced of the above unconditioned connections and elaboration of a new "cross" connection consisting in that tactile stimulation of the ventral side of the paw resulted in flexion in the ulnar joint.     

Reproduction of the electrophysiologic correlates of a conditioned defense reflex following electroconvulsive activity]

Acute and chronic experiments on cats have shown the possibility of obtaining in one session conditioned EEG-responses and vegetative changes as well as conditioned motor reactions time-locked to the moment of the unconditioned pain stimulation omitted during testing. Electro-convulsive stimulation directly after elaboration prevents the appearance of conditioned motor reactions, while conditioned EEG and vegetative changes are retained after electric seizures. A conclusion has been drawn that the emotional component of conditioned reactions is not subjected to the amnestic effect of electro-convulsive action.     

Ultrastructure of the hypophysiotropic region of the hypothalamus in early ontogenesis in rats]

The results of electron microscopic studies have shown that the 16--18 days old rat embryos already have in the hypophysiotropic area some structures necessary for the realization of neuroendocrine regulations. In the arcuate nuclei, the neurosecretory cells differentiate which are capable to synthesize specific neurosecretory granules of 800--1,000 A in diameter. In the median eminence, the primary portal capillaries develop with which tanicytes and a few axon terminals make contact. One can see in the tanicytes the signs of active transport and accumulation of electron dense polymorphic material. All these phenomena are strengthen during the subsequent development. Hence, several days are before birth the neurosecretory and glial elements of the embryos show the signs of functional activity which strengthen during ontogenesis and are expressed most distinctly in the adult animals.     

Variation of mechanical and biochemical parameters of pressure-loaded rabbit hearts following chronic administration of dipyridamole]

After constricting the aorta ascendens of rabbits, the influence of chronic administration of dipyridamole (8 mg/kg i.m. on 6 out of 7 days of the week for 3 months) upon heart hypertrophy, hemodynamics and the hydroxyproline content in the right and left ventricles, the incorporation rate of 2-[14C]-glycine into the actomyosin and soluble protein of the left ventricle was studied. The dipyridamole treatment had no effect on the increase in systolic pressure, the contractility index of the aorta-stenosed animals and heart rate. In contrast, the hypertrophic development, and consequently the increase in hydroxyproline concentration and the increased incorporation rate of 2-[14C]-glycine into the soluble protein were inhibited. The possible mechanism of action of dipyridamole on the development of heart hypertrophy in the rabbit is discussed.     

Effect of arginine deficiency on the reproduction of human cytomegalovirus.

In arginine-deprived human embryonic fibroblasts the reproduction cycle of human cytomegalovirus (CMV) is incomplete. Infectious virus cannot be demonstrated in cell disintergrates, and from among the CMV antigens only the diffuse cytoplasmic antigen is detectable by immunofluorescence. The antigens localized in the cell membrane and those appearing during the complete cycle as large granules or inclusion-like bodies in the nucleus do not appear in the absence of arginine. The CMV genome persists in the arginine-deprived culture; after re-feeding with arginine-containing medium, maturation of virions soon ensues. Maturation could be prevented by inhibitors of protein synthesis, but not by DNA inhibitors, added simultaneously with completion of the medium.     

Dynamics of the human heart rate during changes of posture under various climatic conditions]

The time course of the heart rate (15-sec-periods) during active orthostasis (10 min) was investigated according to types found by Drischel et al. under different climatic conditions in 51 female and 50 male subjects. Constant types were observed in each subject in 3 repeated tests on different days at 20 degrees C and 55% R.H., the types remaining constant even at 25 and 90% R.H. The increase in environmental temperature from 15 to 30 and 45 degrees C showed a significant alteration from type A via different transitional types to type B. At 45 degrees C, an additional type was observed called superhigh type B, functionally being a precollapse type. The variation in typology includes the dynamics of the initial process of the active orthostasis as well as the deviation between the steady-state of the heart rate in erect and in supine position. The physiological mechanisms eliciting the changes in the dynamic behaviour and the correlations with the effective temperature are discussed.