A transistor pH electrode (pH-ISFET electrode) was placed in each of four human mouths and bacteria were allowed to accumulate on it for 1, 2 or 3 days. Changes of plaque pH were measured in situ after application of sucrose solution (0.1, 1 or 3%) and, then, quick pH recovery by mouth-rinses with water was estimated. Although the acidic pH after application of 0.1% sucrose was easily and quick...

Diverse enveloped viruses enter host cells through endocytosis and fuse with endosomal membranes upon encountering acidic pH. Currently, the pH dynamics in virus-carrying endosomes and the relationship between acidification and viral fusion are poorly characterized. Here, we examined the entry of avian retrovirus that requires two sequential stimuli--binding to a cognate receptor and low pH--to...

BACKGROUND AND PURPOSE Growth factors released from platelets have potent effects on fracture and wound healing. The acidic tide of wound healing, i.e. the pH within wounds and fractures, changes from acidic pH to neutral and alkaline pH as the healing process progresses. We investigated the influence of pH on lysed platelet concentrates regarding the release of growth factors. MATERIAL AND M...

The influence of adaptation to pH (from pH 5.0 to 9.0) on membrane lipid composition, verotoxin concentration, and resistance to acidic conditions in simulated gastric fluid (SGF) (pH 1.5, 37 degrees C) was determined for Escherichia coli O157:H7 (HEC, ATCC 43895), an rpoS-deficient mutant of ATCC 43895 (HEC-RM, FRIK 816-3), and nonpathogenic E. coli (NPEC, ATCC 25922). Regardless of the strain...

The pulmonary airways are continuously exposed to bacteria. As a first line of defense against infection, the airway surface liquid (ASL) contains a complex mixture of antimicrobial factors that kill inhaled and aspirated bacteria. The composition of ASL is critical for antimicrobial effectiveness. For example, in cystic fibrosis an abnormally acidic ASL inhibits antimicrobial activity. Here, w...

The formation of various types of kidney stones is strongly influenced by urinary pH. An alkaline pH favors the crystallization of calcium- and phosphate-containing stones, whereas and acidic urine pH promotes uric acid or cystine stones. The activity of many transport processes involved in calcium, citrate and phosphate handling are sensitive to changes in systemic or local pH as shown for sev...

Semliki Forest virus (SFV), an enveloped alphavirus, is a well-characterized paradigm for viruses that infect cells via endocytic uptake and low-pH-triggered fusion. The SFV spike protein is composed of a dimer of E1 and E2 transmembrane subunits, which dissociate upon exposure to low pH, liberating E2 and the fusogenic E1 subunit to undergo independent conformational changes. SFV fusion and in...

The Soret absorption band of the ferrous carbon monoxide (CO) complex of cytochrome c peroxidase exhibited a blue shift from 423.7 to 420 nm upon an increase in pH from 6.5 to 8.5. The spectral change was reversible with an isosbestic point at 422 nm. The pH dependence of this spectral change gave a sigmoidal curve fitted well to a theoretical curve of a cooperative release of two protons with ...

The cytotoxicity of some drugs is a function of extracellular pH. We show that this dependence is greatly enhanced at 43 degrees. At this temperature, we have examined the cell-killing ability of four drugs in the pH range of 6.5 to 8.5. For 1,3-bis(2-chloroethyl)-1-nitrosourea, cytotoxicity is minimum at alkaline pH and increases in monotonic fashion as the milieu becomes more acidic. There is...