The effect of an insulin load on rat mast cells]

The increase of heparin secretion by mast cells of kidney capsule and subcutaneous fat has been noted in rats after 30 min intravenous insulin administration in a dose 0.3 U/200 g (by this time the blood sugar concentration lowers by 40%). The index of mast cells saturation with heparin drops by 2.3 and 1.9 times correspondingly. After preliminary administration of protamine sulphate (2 mg/200 g that provokes in rats the status of temporary resistance to the hypoglycemic action of insulin the stimulatory effect of insulin on the function of mast cells does not occur.     

The effect of monoamine oxidase inhibition on formation, fixation and reproduction of temporary connections]

An administration of 100 to 300 mg/kg doses of iprazid to rats and mice leads in 24 hours to a considerably higher serotonin and noradrenaline content in the brain. Defensive conditioning against this background proceeds in the same way as in control animals but the retention of elaborated reflexes is sharply disturbed. A similar effect is produced by 5-oxytryptophane. An iprazid administration after conditioning does not disturb the retention and subsequent achievement of the reflex. Inclusion of S35-methionine in the total proteins of the mice brain does not change under the influence of iprazid. A conclusion has been drawn that inhibition of monoaminoxidase by iprazid does not prevent the formation and reproduction of temporary connections, but deeply disturbs their fixation. It is suggested that the revealed disturbances of fixation of temporary connections are due to the accumulation of serotonin in the brain, which suppresses the protein synthesis in the synaptosomes or that of specific proteins.     

Influence of the maternal effect on allogenic inhibition of hematopoietic stem cells]

Bone marrow cells (0,5-10(6)) of female mice of CBA or C57BL strains were injected intravenously to lethally irradiated CBA, C57BL/6, (femaleCBA X maleC57BL/6)F1 and (femaleC57BL/6 X maleCBA)F1 mice. Spleen of recipients as assayed for colony count on the 9th day after bone marrow transplantation by the method of Till and McCullouch. Stem cells of CBA mice demonstrated failure of allogenic inhibition in (CBA X C57BL/6)F1 hybrid mice and formed the same number of colonies as in the spleen of syngenic recipients. The level of allogenic inhibition of CBA stem cells transplanted to (C57BL/6 X X CBA)F1 hybrid mice was 50%. Bone marrow cells of C57BL/6 mice formed colonies in spleen of (CBA X C57BL/6)F1 mice at least in 20 times less than in syngenic combination. In the transplantation of bone marrow from C57BL/6 mice to (C57BL/6 X CBA)F1 hybrid mice the allogenic inhibition was less pronounced (77-85%) as compared with the transfer of cells to (CBA X C57BL/6)F1 hybrid mice (95%). The sex of a recipient did not influence the number of formed colonies. The different level of allogenic inhibition of parental stem cells can not be explained by the effect of linkage with sex as the female of reciprocal hybrid mice have identical structure of sex chromosomes (X(CBA)XC57BL/6). The data obtained indicate that the maternal effect affects allogenic inhibition of stem cells in parent--F1 system. It is possible that the maternal influence may be determined by cytoplasmic factors of inheritance which affect the expressivity of recessive genes Hh, controlling the inheritance of specific haematopoietic cell antigens.     

The effect of an artificial magnetic field on Salmonella infection in mice]

Experimental Salmonella infection in mice, developing simultaneously with the prolonged action of an artificial constant magnetic field with induction equal to 3 x 10(-4) T, was found to induce a pronounced decrease in nonspecific resistance in the animals. The study of Salmonella population structure revealed that the cells selected the animals subjected to the action of the artificial magnetic field had mostly a lesser number of signs of antibiotic resistance. By the end of the experiment Salmonella cultures isolated from the mice subjected to the action of the artificial magnetic field were characterized by greater virulence and resistance to the bactericidal action of blood serum. The use of sodium nucleinate under the conditions of the action of the artificial magnetic field enhanced the level of anti-infectious protection in the animals, which changed the direction of cell selection in Salmonella population towards cells with a greater number of markers of antibiotic resistance.     

The oxygen effect on transcription inhibition in yeast

No oxygen effect is found if X-ray-induced inhibition of ribosomal RNA synthesis in yeast is assessed immediately after exposure. A 20-h liquid holding period, however, leads to a differential recovery in diploid cells which is markedly greater after irradiation in nitrogen. Haploid yeast exhibits a much smaller recovery and does not show any significant difference between exposures in air or nitrogen.     

The effect of various antibiotics on the formation of typhus antibodies following immunization with typhus vaccine]

It was shown that administration in the course of one week, before or after a single use of killed or chemical typhoid vaccine of dibiomycin, biomycin, or biomycin in combination with erythromycin in comparatively high doses produced no negative effect of the production of typhus antibodies and the intensity of antitoxic immunity in albino mice. The same antibiotics failed to influence the antibody formation in guinea pigs if they produced no toxic effect on the animals; but in case of development of toxic phenomena connected with the administration of the mentioned antibiotics a strong depression of antibody production was observed in guinea pigs.     

The effect of plasmin on kallikreinogen]

The effect of purified plasmin preparation on kallikreinogen isolated from rat blood plasma was studied by chromatography on DEAE-Sephadex. Plasmin was shown to affect kallikreinogen to form an active enzyme--kallikrein. The dependence of the activation degree on the plasmin activity and incubation time was studied. Evidence was found for the absence of Hagemann factor in the reaction medium, which excludes the possibility of indirect action of plasmin on kallikreinogen through the Hagemann factor fragments formed.     

The effect of adenosine on caffeine inhibition of plant cytokinesis

Adenosine counteracts caffeine-induced cytokenesis inhibition in meristem cells of onion root tips; counteracts caffeine-induced cytokinesis inhibition in meristen cells of onion root tips; dinitrophenol (DNP) potentiates this caffeine effect. These effects suggest that caffeine could act as a negative, and some adenosine derivatives as a positive, effector on some enzyme(s) essentially involved in cytokinesis. We postulate that caffeine can block cell plate formation by inhibition of a certain ATPase activity essential for membrane fusion of Golgi vesicles. A general mechanism which could explain many of the biological effects of methyloxypurines is proposed.     

The inhibition effect of some n-alkyl dithiocarbamates on mushroom tyrosinase

Three new n-alkyl dithiocarbamate compounds, as sodium salts, C₄H₉NHCS₂Na (I), C₆H₁₃NHCS₂Na (II) and C₈H₁₇NHCS₂Na (III), were synthesized and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) from a commercial source of Agaricus bisporus in 10 mM phosphate buffer pH 6.8, at 293K using UV spectrophotometry. Caffeic acid and p-coumaric acid were used as natural substrates for the enzyme for the catecholase and cresolase reactions, respectively. Lineweaver–Burk plots showed different patterns of mixed and competitive inhibition for catecholase and cresolase reactions, respectively. These new synthetic compounds can be classified as potent inhibitors of MT due to K_i values of 0.8, 1.0 and 1.8 μM for cresolase inhibitory activity, and also 9.4, 14.5 and 28.1 μM for catecholase inhibitory activity for I, II and III, respectively. They showed a greater potency in the inhibitory effect towards the cresolase activity of MT. Both substrate and inhibitor can be bound to the enzyme with negative cooperativity between the binding sites (α>1) and this negative cooperativity increases with increasing length of the aliphatic tail in these compounds. The inhibition mechanism is presumably related to the chelating of the binuclear coppers at the active site and the different K_i values may be related to different interaction of the aliphatic chains of I, II and III with the hydrophobic pocket in the active site of the enzyme.     

The effect of spermidine on endonuclease inhibition by agarose contaminants

A simple method for the determination of molecular weight and effective size of proteins is proposed. The procedure consists in comparison of sedimentation coefficients of reversed micelles of aerosol OT in octane in the presence and in the absence of solubilized protein.     

The inhibition effect of some n-alkyl dithiocarbamates on mushroom tyrosinase

Three new n-alkyl dithiocarbamate compounds, as sodium salts, C4H9NHCS2Na (I), C6H13NHCS2Na (II) and C8H17NHCS2Na (III), were synthesized and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) from a commercial source of Agaricus bisporus in 10 mM phosphate buffer pH 6.8, at 293K using UV spectrophotometry. Caffeic acid and p-coumaric acid were used as natural substrates for the enzyme for the catecholase and cresolase reactions, respectively. Lineweaver-Burk plots showed different patterns of mixed and competitive inhibition for catecholase and cresolase reactions, respectively. These new synthetic compounds can be classified as potent inhibitors of MT due to Ki values of 0.8, 1.0 and 1.8 microM for cresolase inhibitory activity, and also 9.4, 14.5 and 28.1 microM for catecholase inhibitory activity for I, II and III, respectively. They showed a greater potency in the inhibitory effect towards the cresolase activity of MT. Both substrate and inhibitor can be bound to the enzyme with negative cooperativity between the binding sites (alpha > 1) and this negative cooperativity increases with increasing length of the aliphatic tail in these compounds. The inhibition mechanism is presumably related to the chelating of the binuclear coppers at the active site and the different Ki values may be related to different interaction of the aliphatic chains of I, II and III with the hydrophobic pocket in the active site of the enzyme.     

Intercellular adhesiveness and neuraminidase effect following release from density inhibition of cell growth

Mutual cell adhesion increases when HeLa cells growing in suspension culture are released from density inhibition of growth. Neuraminidase treatment considerably enhances the adhesiveness of density inhibited cells but produces only a small effect on cells at low density.     

Membrane differentiations of an absorptive epithelium covering embryonic trophotaeniae in a goodeid teleost

Summary The trophotaenial absorptive cells (TACs) in goodeid embryos facilitate nutrient absorption during prolonged periods of intraovarian gestation. In a study of membrane differentiations associated with solute and ligand transfer in the trophotaeniae of Xenotoca eiseni, embryos were incubated in vivo with cationized ferritin (CF) prior to freeze-cleaving. This exposure to high concentrations of an adsorptive ligand was meant to induce swelling of the endosomal compartment. Macromolecular trafficking in TACs occurs via an apical endocytic complex consisting of plasma membrane invaginations, a large population of small vesicles, uniformly thick apical tubules, and endosomes. Freeze-fracture replicas showed that the microvillar plasma membrane P-face of TACs was studded with intramembrane particles (IMPs) at a fairly high density, whereas that of the cell surface proper contained a distinctly lower density and the tubulovesicular endocytic pits contained almost no IMPs. The majority of small vesicles and apical tubules in a near surface position displayed P-fracture faces with only a few odd IMPs, indicating that membrane, shuttling between the apical plasma membrane and intracellular sorting organelles, obviously does not carry along many large-sized integral membrane proteins. The distended endosomal compartment had many P-face-associated particles primarily clustered into patches. Specializations of the lateral plasma membrane included 4–8 tight junctional strands, relatively large complements of gap junction proteins, and numerous plaques of desmosomal membrane particles. A system of lamellar cisternae underlay the lateral cell surface that was in continuity with the intraepithelial space by numerous tubular canals, giving rise to an intracellular amplification of the basolateral plasma membrane. Their outward openings appeared as tiny pits on the cytoplasmic faces of freeze-cleaved cell membrane. The density of IMPs on the P-faces of the surface plasma membrane was apparently lower than that on its invaginated lamellar complex. Hence, it is concluded that the mobility of integral membrane proteins in the plane of the membrane may be hampered in movement across the surface pores.Supported by the Deutsche Forschungsgemeinschaft (Schi 268/1-1)