Mechanisms through which ammonia regulates cortical collecting duct net proton secretion.

Ammonia stimulates cortical collecting duct (CCD) net bicarbonate reabsorption by activating an apical H(+)-K(+)-ATPase through mechanisms that are independent of ammonia's known effects on intracellular pH and active sodium transport. The present studies examined whether this stimulation occurs through soluble N-ethylmaleimide-sensitive fusion attachment receptor (SNARE) protein-mediated vesicle fusion. Rabbit CCD segments were studied using in vitro microperfusion, and transepithelial bicarbonate transport was measured using microcalorimetry.

Issues for improving multiplasmid DNA vaccines for HIV-1.

Since the first reports of plasmid vaccines, there have been substantial changes made to the design of plasmid backbones, as well as to the antibiotic resistance markers chosen for clinical vectors compared with first generation vectors. These changes aid manufacturing, production and scale up and at the same time aid conceptual safety by limiting the ability of the vaccines to transfer useful genetic selection genes to other bacterial infectious agents. In contrast, there has been little change to the original promoters or polyadenlyation tracts in the last decade.

Evidence for a model of agonist-induced activation of 5-hydroxytryptamine 2A serotonin receptors that involves the disruption of a strong ionic interaction between helices 3 and 6.

5-Hydroxytryptamine 2A (5-HT2A) receptors are essential for the actions of serotonin (5-hydroxytryptamine (5-HT)) on physiological processes as diverse as vascular smooth muscle contraction, platelet aggregation, perception, and emotion. In this study, we investigated the molecular mechanism(s) by which 5-HT activates 5-HT2A receptors using a combination of approaches including site-directed mutagenesis, molecular modeling, and pharmacological analysis using the sensitive, cell-based functional assay R-SAT. Alanine-scanning mutagenesis of residues close to the intracellular end of H6 of the 5-HT2A receptor implicated glutamate Glu-318(6.

HIV-1 viral protein R compromises cellular immune function in vivo.

HIV-1 viral protein R (Vpr) is a virion-associated gene product that profoundly affects T cell proliferation, induces apoptosis and can affect cytokine production in part through interfering with NF-kappa B-mediated transcription from host cells. Collectively, these effects support that Vpr could influence immune activation in vivo. However, this effect of Vpr has not been explored previously.

Effects of ammonia on acid-base transport by the B-type intercalated cell.

Ammonia, in addition to its role as a constituent of urinary net acid excretion, stimulates cortical collecting duct (CCD) net bicarbonate reabsorption. The current study sought to begin determining the cellular transport processes through which ammonia regulates bicarbonate reabsorption by testing whether ammonia stimulates B-type intercalated cell bicarbonate secretion, bicarbonate reabsorption, or both. The effects of ammonia on single CCD intercalated cells was studied by use of measurements of intracellular pH taken from in vitro microperfused CCD segments after luminal loading of the pH-sensitive fluorescent dye BCECF.