Functional Effects of Adiponectin on Endothelial Progenitor Cells

Adiponectin is an adipokine whose plasma levels are inversely correlated to metabolic syndrome components. Adiponectin protects against atherosclerosis and decreases risks in myocardial infarction. Endothelial progenitor cells (EPCs) are a heterogeneous population of circulating cells involved in vascular repair and neovascularization. EPCs number is reduced in patients with cardiovascular disease. We hypothesize that the positive effects of adiponectin against atherosclerosis are explained in part by its interactions with EPCs. Cells were obtained from healthy volunteers' blood by mononuclear cell isolation and plating on collagen‐coated dishes. Three sub‐populations of EPCs were identified and characterized using flow cytometry. EPCs' expression of adiponectin receptors, AdipoR1, and AdipoR2 was evaluated by quantitative PCR. The effects of recombinant adiponectin on EPCs' susceptibility to apoptosis were assessed. Finally, expression of neutrophil elastase by EPCs and activity of this enzyme on adiponectin processing were assessed. Quantitative PCR analysis of EPCs mRNAs showed that AdipoR1 mRNA is expressed at higher levels than AdipoR2. Expression of AdipoR1 protein was confirmed by western blot. Adiponectin significantly increased survival of two sub‐populations of EPCs in conditions of serum deprivation. Such effect could not be demonstrated in the third EPCs sub‐population. We also demonstrated that EPCs, particularly one sub‐population, express neutrophil elastase. Neutrophil elastase activity was confirmed in EPCs' conditioned media. Adiponectin protects some EPCs sub‐populations against apoptosis and therefore could modulate EPCs ability to induce repair of vascular damage. Neutrophil elastase activity of EPCs could locally modulate adiponectin activity by its involvement in the generation of the globular form of adiponectin.     

Physiological and pathogenic characteristics of Nocardia brasiliensis isolated from human mycetomas

A previous analysis of the physiological properties of Nocardia brasiliensis strains isolated from soil of Tucumán proves that non-pathogenic strains have a different behaviour pattern from the pathogenic strains.In the present paper, 16 Nocardia brasiliensis strains isolated from human mycetomas were studied in the same way. The object is to determine if any of the Nocardia brasiliensis present in soil can produce human mycetomas.The macro and micromorphological, biochemical (17 tests), physiological (4 tests) and pathological characteristics were determined for each of the strains. Experimental pathogenicity was determined using albino Swiss mice by inoculation into the footpads.The strains of Nocardia brasiliensis that cause human mycetomas have the same physiological pattern and experimental pathogenicity as the virulent strains present in soil.     

Ethylene and in vitro rooting of hazelnut (Corylus avellana) cotyledons

Ethylene may be one of the many factors that play a role in rooting. However, in some studies ethylene promoted rooting, while in others it was inhibitory or had no effect. Using cotyledons of hazelnut ( Corylus avellana L. cv. Casina) observations were made of the effect of ethylene precursors on adventitious root formation. l-methionine (Met) or 1-aminocyclopropane-1-carboxylic acid (ACC) added to a standard indole-3-butyric acid (IBA)-kinetin-containing medium did not enhance rooting, while 2-chloroethylphosphonic acid (CEPA) did. The ethylene inhibitor, aminoethoxyvinylglycine (AVG), inhibited root formation, but its effect was reversed by ACC when cotyledonary segments were transferred to rhizogenic medium plus ACC at day 10. Ethylene production by cotyledons cultured on rhizogenic medium or rhizogenic medium plus CEPA was high at the beginning of rooting. Thus, the wound-induced ethylene is a key stimulatory factor in the formation of root primordia. The data support the hypothesis that ethylene plays a positive role in root formation.     

Ab initio molecular orbital study of the mispairing ability of a nucleotide base analogue, N4-aminocytosine

The intrinsic properties of N4-aminocytosine, a base analogue of cytosine, are analyzed by an ab initio molecular orbital method. Relative stabilities of four possible isomeric structures of N4-aminocytosine are shown. The more stable isomer has the smaller dipole moment, so the relative stabilities of the isomers in solutions are subject to solvent polarity. The mutagenicity of this base analogue must arise because it can behave like either cytosine or thymine. It can form a guanine-cytosine-like base pair more easily than cytosine, and an adenine-thymine-like base pair less easily than thymine.     

Effect of Drying Medium on Residual Moisture Content and Viability of Freeze-Dried Lactic Acid Bacteria

The effect of various substances on the relationship between residual moisture content and the viability of freeze-dried lactic acid bacteria has been studied. Compounds such as polymers, which display considerable ability in displacing water, showed no protective action during freeze-drying. Adonitol, on the other hand, produced the smallest change in water content at various times during drying and allowed the highest rate of survival.     

The effect of Cyanophyta upon zooplankton in a eutrophic tropical lake (Lake Valencia,Venezuela)

The effect which Cyanophyta have upon the zooplankton varies according to the form of the alga (mucilaginous colonies or filaments) and its abundance. Periodical blooms of Microcystis aeruginosa were not detrimental for the zooplankton, in spite of the fact that copepods, cladocerans and rotifers consume small colonies. High concentrations of Lyngbya limnetica and Oscillatoria limnetica in Lake Valencia, Venezuela, proved to be inhibitory for cladocerans. A total absence of cladocerans was detected when filaments increased.     

Structural studies of Fc receptors. V. Effect of phospholipase C treatment on the binding activities of the Fc receptor of macrophage or its isolated plasma membrane

The effect of phospholipase C treatment on the binding activity of the Fc receptor of guinea pig macrophage was studied to analyze the interaction of the Fc receptor with membrane phospholipids necessary for the activity. It was confirmed by subcellular fractionation that the receptor is localized on the plasma membrane. Treatment of the whole cell or isolated plasma membrane with phospholipase C of Clostridium perfringens diminished the binding of soluble IgG2-immune complex to Fc receptors on the cell or membrane. On the other hand, phospholipase C of Bacillus cereus did not affect the activity when it acted on the whole cell but it did diminish the activity when it acted on the isolated plasma membrane. Analysis of the phospholipids of untreated and treated macrophages or plasma membrane showed that phosphatidylcholine molecules, particularly those located in the membrane (not accessible to attack from the cell surface by phospholipase C of B. cereus), appear to be crucial for efficient interaction of macrophage Fc receptors with immune complex. Ligand-binding experiments with macrophages showed that the diminished binding activity was due to a decrease of the avidity for immune complex, but did not seem to be due to a decrease in the number or affinity of Fc receptors for monomeric IgG2. Taken together with the previous results which demonstrated that Fc receptors which had apparently lost the activity due to delipidation could be reconstituted with phosphatidylcholine but not with most other phospholipids, the results seem to indicate that the diminution of the binding activity to the immune complex of macrophage or its plasma membrane caused by phospholipase C treatment is due to the impairment of multivalent interaction between Fc receptor molecules on the membrane and IgG2 molecules in the immune complex, probably as a result of the loss of interaction of the head groups of phospholipids with Fc receptor molecules and the change in membrane properties resulting from the increase of diglycerides.     

The sre gene (ORF469) encodes a site-specific recombinase responsible for integration of the R4 phage genome.

The sre gene (ORF469) of the R4 phage encodes a protein similar to the resolvase-DNA invertase family proteins. Insertional gene disruption of sre prevented a lysogen from entering the lytic cycle, implying that Sre protein is a site-specific recombinase needed for excision of the R4 prophage genome (M. Matsuura, T. Noguchi, T. Aida, M. Asayama, H. Takahashi, and M. Shirai, J. Gen. Appl. Microbiol. 41:53-61, 1995). To determine whether this sre gene is also necessary for the integration reaction, we studied its function by integration plasmid analysis. When deletions, frameshifts, and site-directed mutations that caused an amino acid substitution of Ser-17 for Ala were introduced into the sre structural gene, transformation efficiency of Streptomyces parvulus 2297 with these plasmid DNAs was severely reduced. However, an adenine insertion just before the possible initiation codon of the sre gene did not significantly decrease the efficiency. These data suggest that the Sre protein is a site-specific recombinase responsible for integration of the R4 phage genome.