Neutral alpha-mannosidase in human B- and T-lymphoid cells]

The presence of neutral alpha-mannosidase activity in normal and pathological lymphoid cells has been demonstrated. The specific activities of the enzyme in different cell types were similar with the exception of B-cells from B-CLL patients when it was a little higher. The activity of acid alpha-mannosidase was also determined in these lymphoid cells. The neutral to acid alpha-mannosidase activity ratio was different in B- and T-cells: in the former neutral alpha-mannosidase activity prevailed, whereas in the latter the predominance of acid alpha-mannosidase activity was apparent. Neutral alpha-mannosidases from pathological B- and T-cells were partially purified and their properties were investigated. In both cell types the enzyme was localized in the cytosol, was very labile and could be stabilized with Mn2+ and dithiothreitol. The enzyme was activated by Co2+ and inhibited by Zn2+ and EDTA. Swainsonine inhibited the B-cell neutral alpha-mannosidase somewhat more strongly in comparison with the T-cell enzyme.     

The intercentral relations of the frontal cortex and limbic structures of the brain in dogs]

In 3 dogs with implanted electrodes, in conditioned experiments correlation of the bioelectrical processes was studied by coherence function calculation of the hippocampus, hypothalamus, amygdala and frontal cortex biopotentials. It was shown, that the level of maximum values of coherence function of bioelectrical oscillations, led from various pairs of the studied brain structures significantly differed both in magnitude and frequency at which the greatest synchronization of biopotentials was noticed. In one dog with a high degree of connection between the hippocampus and hypothalamus biopotentials oscillations, a low synchronization of the frontal cortex and amygdala oscillations was found; in two other animals with a higher level of coherence between the oscillations of the frontal cortex and amygdala biopotentials, a lower degree of connection between the oscillations led from the hippocampus and hypothalamus was revealed. Synchronization of the biopotentials of the hippocampus and frontal cortex and also of the hippocampus and amygdala biopotentials proved to be low in all experimental dogs, what additionally testifies to different role of these structures in organization of the behaviour.     

Changes in the electrical activity of the hippocampus during elaboration of an inhibitory reaction in the dog

A conditioned alimentary instrumental reflex was elaborated in three dogs with chronically implanted electrodes to a consecutive complex conditioned stimulus consisting of two equal acoustic stimuli separated by a pause. At first, the animals reacted with motor reactions during the whole action of the complex signal. Then inhibition of reaction was elaborated at first in pause and then in response to the preparatory stimulus. In the process of stabilization of inhibition, there was an increase of similarity of spectral composition of hippocampal theta-rhythm with the values obtained in the inter-signal period. Conclusion is made that the hippocampus is not a structure necessary for the elaboration of internal inhibition. The frequency of hippocampal theta-rhythm may serve as a characteristic of the property called in Pavlov's school mobility of the nervous system.     

Instrumental heterogeneous responses to 2 successive complex stimuli with a common initial stimulus in the dog

Formation and achievement of heterogenous instrumental reflexes to two consecutive complex stimuli was studied in dogs. Under the action of conditioned complex stimulus tone--Pause--tone, the dogs may be trained not to have a motor response to the first tone presentation, but perform alimentary instrumental reaction only to its repeated administration. Introducing into the experiment not only alimentary but also defensive complex stimulus stone-pause--light resulted in a change in animal's reactions in such a sequence: at first alimentary instrumental reaction was disinhibited under the action of the preparatory stimulus and during the pause, then bieffector responses appeared, further on in most of the dogs motor defensive reactions mainly took place. Trigger stimuli evoked the adequate instrumental reaction.     

Formation of antibiotic 2562 by a culture of the actinomycete, Streptomyces griseovariabilis]

An actinomycetous culture 2562 inhibiting the growth of gramnegative bacteria was isolated from a soil sample. The culture was classified as Streptomyces griseovariabilis. It was found that culture 2562 produced an antibiotic belonging to the group of novobiocin. It consists of 2 components. One of them is identical to chlorobiocin and the other is a minor component of this group. Some parameters of the antibiotic complex production by strain 2562 under submerged conditions were studied. Nutrient media providing the predominant biosynthesis of the first (main) or the second component of the antibiotic were developed.     

New species, Actinomadura fulvescens sp. nov. and Actinomadura turkmeniaca sp. nov. and their antagonistic properties

Two new species of Actinomadura isolated from soil samples of the Turkmen SSR, i.e. Actinomadura fulvescens sp. nov. and Actinomadura turkmeniaca sp. nov. are described. The first species is characterized by formation of short (1-2 turns) spiral spore chains, smooth spores, scanty white aerial mycelium, colourless or yellowish substrate mycelium on synthetic media and brownish-yellow substrate mycelium and soluble pigment of the same colour on organic media. No melanoid pigment is secreted. The type culture is designated as INA 3321. The cultures of A. fulvescens show antibiotic activity. A. turkmeniaca is characterized by formation of short straight or spiral spore chains, smooth spores, scanty white aerial mycelium, substrate mycelium and soluble pigment of pinkish-violet colour, absence of melanoid pigment. The type culture is designated as INA 3344. The strains of this species have low antibiotic activity. The study on the use of carbon sources by the representatives of 7 species (9 strains) of Actinomadura showed that the majority of the cultures (5 species, 7 strains) produced no growth on the Pridham and Gottlieb medium (ISP-9) with various carbon sources, including glucose. Possibly this medium cannot be used as the main medium for investigation of the spectrum of carbohydrate consumption in Actinomadura.     

Generalization of the experience of programmed control of the knowledge of students in normal anatomy]

Due to increasing significance of application of programmed control of knowledge in the process of teaching students the development and use of such method has been undertaken at the Department of Normal Anatomy of the Pavlov First Medical Institute since 1968 for examining students of the first and second year. The method was used in combination with a usual traditional form of examining. Rapid "selection" of students satisfactorily prepared for further talk at the examination, objectivity of the mark and determination of questions which should be paid special attention at the second half of the examination are positive sides of the method. The article presents tables with results of programmed control of knowledge in anatomy of students of the first and second years of medical and stomatological faculties for the last 3 years.     

Effect of O-methylhydroxylamine on extracellular phage cd]

Study was made of lethal and mutagenic effect of 1 M and 0,5 M O-methylhydroxylamine (OMHA) on extracellular phage Sd. The correlation between chemical changes of the genome and the degree of phage inactivation under the action of OMHA has been established within the range of studied pH (4,5-7,0) of the reaction medium. OMHA in activates the phage at the highest rate at pH 5,0, which agrees with chemical data indicating that the total rate of OMHA modification of cytidine units is maximal at this pH. Inactivation curves of OMHA-treated phage are single-hit at pH investigated, but have a small initial shoulder; at pH 5,0 and 4,5 inactivation curves consist of two exponents, the second exponent having the smallest slope, that is the phage is characterized by an increased resistance to OMHA at this section. The increased phage resistance can be explained by transforming the original product IV (cross-linked with protein) into the product II (N4-methoxy-6-methoxyamine-5,6-dihydrocytidine) which can be repaired in contrast to IV. OMHA has a high mutagenic effect on phage Sd. Under optimal conditions (at pH 4,5) the mutagen induces plaque mutants (up to 6%) among survived phages. The data obtained correlate with the fact that with decreasing pH (from 5,0 to 4,5) the ratio of the "mutagen" unit - N4-methoxycytidine (product III) to the "inactivating" one (product II) increases. The curves of mutation induction under the action of OMHA have a characteristic form with the initial linear section and the maximum or the plateau similar to mutation curves to be observed under the action of radiation and chemical agents.     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Antibiotic N',N''-dibenzyleremomycin with reduced 1,2-peptide bond

Eremomycin derivatives with benzylated amino groups of both residues of eremosamine and with (R) or (S)-2-amino-4-methylpentyl substituted for N-methyl-D-Leu, the first amino acid residue of its heptapeptide, were synthesized to study the role of the peptide bond between the first and the second amino acid residues of the heptapeptide moiety of the antibiotic in its interaction with the precursors of the bacterial cell wall peptidoglycan and exhibition of its antibacterial activity. Comparison of the antibacterial activities of N',N"-dibenzyleremomycin, de-(N-methyl-D-Leu)-N',N"-dibenzyleremomycin, and its N-(2-amino-4-methylpentyl)-derivative (1,2-deoxo-N',N"-dibenzyleremomycin) demonstrated that cleavage or replacement of the first amino acid residue by the corresponding aminoalkyl residue results in a decrease in its antibacterial activity towards both vancomycin-sensitive and vancomycin-resistant strains of microorganisms. The English version of the paper.