In this study, we determined the internal cellular pH response of Leuconostoc mesenteroides and Lactobacillus plantarum to the external pH created by the microorganisms themselves or by lactic or acetic acids and their salts added to the growth medium. Growth of Leuconostoc mesenteroides stopped when its internal pH reached 5.4 to 5.7, and growth of L. plantarum stopped when its internal pH rea...

Conventional electrophoretic techniques for the identification offish species are limited in the resolution and reproducibility needed for the reliable identification of fish species. This paper describes the potential of a high resolution protein separation technique, thin-layer polyacrylamide gel isoelectric focusing (IEFl, as a new means of identifying fish species. Sarcoplasmic protein patt...

Ultrathin layers of polyacrylamide gel bound to glass can be washed, air-dried, and stored for at least 1 year before rewetting in ampholyte solutions for isoelectric focusing. Short-term drying affects neither fluorescent banding of the ampholytes (not evident in conventional gels) nor resolution of complex protein mixtures while prolonged storage seems to have no deleterious effects. Layers a...

BACKGROUND Differentiation of pulmonary arterial hypertension (PAH) and pulmonary venous hypertension (PVH) often requires right heart catheterization (RHC). We sought to determine whether a combination of clinical and echocardiographic variables could predict the pulmonary diastolic to wedge (PAd-PWP) gradient and thus differentiate patients with PAH and PVH. METHODS We prospectively enrolle...

The electrical and chemical components of the electrochemical proton gradient of submitochondrial particles can be monitored simultaneously by continuously recording optical signals from the probes oxonol-VI and 9-aminoacridine. Either respiration or ATP hydrolysis causes a red shift in the absorption spectrum of oxonol-VI indicative of a membrane potential and a decrease of the fluorescence of...

Evidence is presented indicating that the carrier-mediated uptake of 3-deoxy-2-oxo-D-gluconate and D-glucuronate in Escherichia coli K12 is driven by the deltapH and deltapsi components of the protonmotive force. 1. Approximately two protons enter the cells with each sugar molecule, independent of the sugar and the strain used. 2. In respiring cells, the magnitude of the pH gradient alone, as m...

Recent classifications of the several pathophysiologic types of distal renal tubular acidosis (secretory, voltage dependent, and gradient) have been based on the response of acidification parameters to a series of provocative maneuvers in vivo and in vitro. A reduction in the difference in urine and blood CO2 tension during bicarbonate loading (U-B pCO2 gradient), a widely applied parameter, ha...

The proton gradient from the intracellular space to plasma creates an unbound drug gradient for weak acids and bases that could modulate apparent drug clearance and drug-drug interactions. Cytochrome P450 intrinsic clearance and inhibitor potency are routinely determined in vitro at the plasma pH of 7.4 rather than the intrahepatocyte pH of 7.0. We determined the impact of pH on in vitro enzyme...

Putrescine uptake and the kinetics of this uptake were studied in petals of Saintpaulia ionantha Wendl. Uptake experiments of [(3)H] or [(14)C] putrescine were done on single petals at room temperature at various pH values. The results show that putrescine uptake occurs against a concentration gradient at low external putrescine concentration (0.5-100 micromolar) and follows a concentration gra...

Existence of a proton-translocating ATPase on the tonoplast of higher plants has been further confirmed by use of two experimental systems: (a) intact isolated vacuoles from sugarcane cells and (b) vesicles prepared from the same source. Addition of MgATP to vacuoles polarized the tonoplast by 40 millivolts to a value of +20 millivolts, but a large preexisting pH gradient across the membrane re...