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.     

Synthesis and properties of an organophosphorous regulator of hemoglobin oxygenation

Racemic 1-O-(epsilon-aminohexanoyl)-2,3-diphosphoglycerol (ADPG) was synthesized. The pH dependence of the 31P-NMR spectra was studied for the ADPG cyclohexylammonium salt. ADPG binding to hemoglobin and its functional activity as a regulator of human hemoglobin reversible oxygenation were assayed.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Anticoagulant activity of fucoidans from brown algae

The anticoagulant activity of polysaccharide fucoidans from 11 species of brown algae was studied. The anticoagulant activity was measured by the activated partial thromboplastin time (APTT), prothrombin time, and thrombin time. Inhibitory action of these fucoidans significantly varied from one species to another. Fucoidans from Laminaria saccharina and Fucus distichus exhibited high anticoagulant activity, while fucoidans from Cladosiphon okamuranus and Analipus japonicus were almost inactive. Other fucoidans exhibited intermediate inhibitory activity. The inhibitory effect of fucoidans on thrombin and factor Xa was investigated in the presence or in the absence of natural thrombin inhibitor, antithrombin III (AT III). In contrast to the best-studied anticoagulant, heparin, most of these fucoidans inhibited thrombin in the absence of AT III. In the presence of AT III the inhibitory effect of fucoidans considerably increased. In contrast to heparin, fucoidans weakly influenced factor Xa activity in the presence of AT III and their inhibitory effect was not observed in the absence of AT III. There was no correlation between the anticoagulant activities of this series of fucoidans and their anti-inflammatory action, studied earlier. It is suggested that these two types of fucoidan activities depend on different structural features of fucoidans. Results of this study demonstrate a possibility of preparation of fucoidans with high anti-inflammatory activity but low anticoagulant activity. Anticoagulant activity of the fucoidans did not exhibit direct dependence on the content of fucose, the other neutral sugars and sulfates; no dependence was also found between the anticoagulant activity and the structure of the backbone of their molecules.     

Effects of moderate ammonium enrichment on three submersed macrophytes under contrasting light availability

1. Increased ammonium concentrations and decreased light availability in a water column have been reported to adversely affect submersed vegetation in eutrophic waters worldwide. 2. We studied the chronic effects of moderate enrichment (NH₄–N: 0.16–0.25 mg L^?1) on the growth and carbon and nitrogen metabolism of three macrophytes (Ceratophyllum demersum, Myriophyllum spicatum and Vallisneria natans) under contrasting light availability in a 2‐month experiment. 3. The enrichment greatly increased the contents of free amino acids and nitrogen in the shoot / leaf of the macrophytes. This indicates that was the dominant N source for the macrophytes. 4. Soluble carbohydrate contents remained relatively stable in the shoot / leaf of the macrophytes irrespective of the treatments. Under ambient light, the starch contents in the shoot / leaf of C. demersum and M. spicatum increased with enrichment, whereas V. natans did not exhibit any change. The starch contents decreased in C. demersum, increased in M. spicatum and remained unchanged in V. natans after the combined treatment of enrichment and reduced light. 5. The enrichment did not affect the growth of the three macrophytes under the ambient light. However, it did suppress the growth of C. demersum and M. spicatum under the reduced light. The results indicate that a moderate enrichment was not directly toxic to the macrophytes although it might change their viability in eutrophic lakes in terms of the carbon and nitrogen metabolism.     

Immunogenic properties of neomycin conjugates with macromolecular carriers]

To obtain diagnostic antibodies to neomycin, immunogenic properties of the neomycin conjugates with macromolecular carriers were studied. Bovine serum albumin and copolymers of N-vinylpyrrolidone with crotonic acid and N-hydroxyphthalimide ether of crotonic acid were used as carriers. It was shown that immunization of mice by the conjugates in combination with Freund's adjuvant resulted in production of neomycin antibodies, the titer being 1/80 to 1/130. When the antibiotic conjugates with the copolymers of N-vinylpyrrolidone were used and not the neomycin conjugates with the carrier of the protein nature, the neomycin antibodies were produced in the absence of Freund's full adjuvant. With the use of the isolated antibodies to neomycin a method for indirect solid phase enzyme immunoassay of neomycin was developed at the minimum detectable level of 25 ng/ml.     

Special effects of a complex probiotic containing cellulolytic bacteria Cellulomonas on actively growing rabbits

It was shown that the association of probiotic bacteria of the genuses Bacillus and Cellulomonas form biolayers on the surface of beet marc particles. The positive effect of a fodder additive that contained the biolayer on the basis of a phytomatrix on the growth and development of young rabbits was shown. Feeding of animals with a mixed fodder that contained 0.1% preparation resulted in stimulation of digestion of all components of the food. Among other components of the mixed fodder, cellulose was digested most effectively. An increase in the biomass of symbiotic bacteria and enzymatic activity in the blindgut chymus was also observed. The positive nitrogen balance demonstrated an increase in the nitrogen content in animals and a decrease of its losses with excretion. The mechanism of response of the rabbit’s organism to introduction of the complex probiotic preparation into the digestive tract is discussed.     

Differences between integrin α5β1 and EGRF receptor in signal pathways controlling proliferation and apoptosis of MCF-7/Dox human breast carcinoma cells

In MCF-7/Dox human breast carcinoma cells, down-regulation of integrin α5β1 and inhibition of epidermal growth factor receptor (EGFR) markedly reduced cell proliferation. Cell cycle analysis showed that α5β1 down-regulation resulted in cycle arrest at the S-phase, followed by a significant increase in the population of apoptotic cells (subG₁ population). Inhibition of EGFR activity also caused cell cycle arrest at the S-phase but without any increase in the subG₁ population. Down-regulation of α5β1 and EGFR inhibition resulted in a significant decrease of cell content of the active (phosphorylated) forms of FAK and Erk protein kinases. The data obtained suggest that α5β1 integrin is implicated in cell growth control via inhibition of apoptotic cell death and through EGFR activation.