Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats

Abstract We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains ( P < 0.0001. Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.     

Further indications of the multicomponent nature of the acrosome reaction-inducing substance of human follicular fluid

Human follicular fluid (hFF), which has been treated with either unspecific proteases or dextran-coated charcoal (DCC) to remove proteins and/or steroids, cannot successfully induce the acrosome reaction (AR). After the removal of steroids, AR-inducing activity can be restored to hFF by supplementation with exogenous progesterone, but only in the presence of intact protein. Gel filtration experiments with ³H-progesterone-labelled hFF showed elution of the radioactive signal in the high molecular weight range, corresponding to bound progesterone. AR-inducing activity was seen in exactly the same fraction. Based on these results, the acrosome reaction-inducing substance (ARIS) appears to be a complex of progesterone and a progesterone-binding protein, which was shown to be identical with the plasma protein corticosteroid-binding globulin (CBG) by immunological techniques. AR induction was only observed in the presence of both CBG and progesterone, suggesting a combined effect of the two components. © 1995 wiley-Liss, Inc.     

A rare genetically determined variant of psuedocholinesterase in two German families with high plasma enzyme activity.

Activity of pseudocholinesterase (acylcholine-acyl-hydrolase) elevated up to four times has been detected in sera of members of two German families. The catalytic concentrations of the pseudocholinesterase of the afflicted members of both families (male and female) varied between 4800 U/l and 10 200 U/o (acetylthiocholine iodide substrate). The pseudocholinesterase of the propositi exhibits isoenzyme separation patterns in polyacrylamide electrophoresis as well as in electrofocussing which are different from those of pseudocholinesterase from normal persons. No differences could be seen as regards the Km of substrates or the inhibition by dibucaine, fluoride or succinyldiocholine.     

Surfactin and fengycin contribute to the protection of a Bacillus subtilis strain against grape downy mildew by both direct effect and defence stimulation

Bacillus subtilis GLB191 (hereafter GLB191) is an efficient biological control agent against the biotrophic oomycete Plasmopara viticola, the causal agent of grapevine downy mildew. In this study, we show that GLB191 supernatant is also highly active against downy mildew and that the activity results from both direct effect against the pathogen and stimulation of the plant defences (induction of defence gene expression and callose production). High-performance thin-layer chromatography analysis revealed the presence of the cyclic lipopeptides fengycin and surfactin in the supernatant. Mutants affected in the production of fengycin and/or surfactin were thus obtained and allowed us to show that both surfactin and fengycin contribute to the double activity of GLB191 supernatant against downy mildew. Altogether, this study suggests that GLB191 supernatant could be used as a new biocontrol product against grapevine downy mildew.     

Relationship between extra and intracellular sources of calcium and the contractile effect of thiopental in rat aorta

To evaluate the relationship between the vasocontractile effect of thiopental and the extra and intracellular sources of Ca2+, we analyzed both the contractile effect of the barbiturate on rat aortic rings and its ability to modify the intracellular calcium concentration in cultured rat aorta smooth muscle cells. Thiopental (10-310 microg/mL) contracted aortic rings only in the presence of extracellular Ca2+, and this effect was not blocked by verapamil or diltiazem. On the contrary, Ca2+ (0.1-3.1 mM) evoked contractions only when thiopental (100 microg/mL) was present. Although in calcium-free solution thiopental (100 microg/mL) did not contract aortic rings, it abolished the contractile effect of either phenylephrine (10(-6) M) or caffeine (10 mM). Finally, thiopental augmented the intracellular calcium concentration in cultured smooth muscle cells incubated either in the presence or absence of calcium. In conclusion, thiopental's vasocontractile effect depends on extracellular calcium influx, which is independent of L-calcium channels. The increase in intracellular Ca2+ concentration elicited by thiopental in Ca2+-free solution and its ability to block the effect of phenylephrine and caffeine suggest that this barbiturate can deplete intracellular pools of calcium. Therefore, the calcium entry pathway associated with the contractile effect of thiopental may correspond to the capacitative calcium entry model.     

One step purification of corilagin and ellagic acid from Phyllanthus urinaria using high-speed countercurrent chromatography

High-speed countercurrent chromatography (HSCCC) has been successfully applied to the preparative separation of corilagin and ellagic acid in one step from the Chinese medicinal plant Phyllanthus urinaria L. by use of direct and successive injections of a crude methanolic extract. Some aspects concerning the practical use of this technique in the described application are considered.     

Rhythmic opening and closing of vesicles during constitutive exo- and endocytosis in chromaffin cells

Constitutive exo- and endocytic events are expected to increase and diminish the cell surface area in small spontaneous steps. Indeed, cell-attached patch-clamp measurements in resting chromaffin cells revealed spontaneous upward and downward steps in the electrical capacitance of the plasma membrane. The most frequent step size indicated cell surface changes of <0.04 microm(2), corresponding to vesicles of <110 nm diameter. Often downward steps followed upward steps within seconds, and vice versa, as if vesicles transiently opened and closed their lumen to the external space. Transient openings and closings sometimes alternated rhythmically for tens of seconds. The kinase inhibitor staurosporine dramatically increased the occurrence of such rhythmic episodes by making vesicle closure incomplete and by inhibiting fission. Staurosporine also promoted transient closures of large endocytic vesicles possibly representing remnants of secretory granules. We suggest that staurosporine blocks a late step in the endocytosis of both small and large vesicles, and that endocytosis involves a reaction cascade that can act as a chemical oscillator.     

Selective Perturbation of Apical Membrane Traffic by Expression of Influenza M2, an Acid-activated Ion Channel, in Polarized Madin–Darby Canine Kidney Cells

The function of acidification along the endocytic pathway is not well understood, in part because the perturbants used to modify compartmental pH have global effects and in some cases alter cytoplasmic pH. We have used a new approach to study the effect of pH perturbation on postendocytic traffic in polarized Madin–Darby canine kidney (MDCK) cells. Influenza M2 is a small membrane protein that functions as an acid-activated ion channel and can elevate the pH of the trans-Golgi network and endosomes. We used recombinant adenoviruses to express the M2 protein of influenza virus in polarized MDCK cells stably transfected with the polymeric immunoglobulin (Ig) receptor. Using indirect immunofluorescence and immunoelectron microscopy, M2 was found to be concentrated at the apical plasma membrane and in subapical vesicles; intracellular M2 colocalized partly with internalized IgA in apical recycling endosomes as well as with the trans-Golgi network marker TGN-38. Expression of M2 slowed the rate of IgA transcytosis across polarized MDCK monolayers. The delay in transport occurred after IgA reached the apical recycling endosome, consistent with the localization of intracellular M2. Apical recycling of IgA was also slowed in the presence of M2, whereas basolateral recycling of transferrin and degradation of IgA were unaffected. By contrast, ammonium chloride affected both apical IgA and basolateral transferrin release. Together, our data suggest that M2 expression selectively perturbs acidification in compartments involved in apical delivery without disrupting other postendocytic transport steps.