The effect of endotoxemia on concanavalin A induced alterations in cytoplasmic free calcium in rat spleen cells as determined with Fluo-3

Microfluidic production of biopolymer microcapsules with controlled morphology

We report a microfluidic approach to generating capsules of biopolymer hydrogels. Droplets of an aqueous solution of a biopolymer were emulsified in an organic phase comprising a cross-linking agent. Polymer gelation was achieved in situ (on a microfluidic chip) by diffusion-controlled ionic cross-linking of the biopolymer, following the transfer of the cross-linking agent from the continuous phase to the droplets. Gelation was quenched by collecting particles in a large pool of cross-linking agent-free liquid. The structure of microgels (from capsules to gradient microgels to particles with a uniform structure) was controlled by varying the time of residence of droplets on the microfluidic chip and the concentration of the cross-linking agent in the continuous phase. We demonstrated the encapsulation of a controlled number of polystyrene beads in the microgel capsules. The described approach was applied to the preparation of capsules of several polysaccharides such as alginate, kappa-carrageenan, and carboxymethylcellulose.

Catecholamine responsiveness in human lymphocytes evaluated by intracellular free calcium measurements

Intracellular free calcium concentration [f(Ca2+)i] and cyclic adenosine monophosphate (cAMP) in lymphocytes and basal plasma noradrenaline (NA) were measured in nine healthy male subjects (age 22-72 years). Lymphocytes were stimulated with isoproterenol and the plant lectin concanavalin A (Con A). Con A induced a dose dependent increase in f(Ca2+)i without increasing inositol lipid turnover. The mechanism by which Con A mobilized f(Ca2+)i is not clear, but we found that the level of prostaglandin E2, a metabolite from arachidonic acid, increased after stimulation with Con A, indicating the possibility of arachidonic acid released by phospholipase A2. Isoproterenol inhibited the Con A-induced calcium mobilization in a dose dependent manner in lymphocytes stimulated with both isoproterenol and Con A. This inhibitory effect of isoproterenol is most probably mediated via cAMP. Both isoproterenol induced increase in cAMP and inhibition of calcium mobilization were significantly correlated to basal plasma NA. Taken together our data indicate that the lymphocyte response to a specific stimulus may depend not only on the strength of this stimulus, but also on the level of sympathetic nerve activity.