We have recently developed a novel in vitro model using HAT-7 rat ameloblast cells to functionally study epithelial ion transport during amelogenesis. Our present aims were to identify key transporters of bicarbonate in HAT-7 cells and also to examine the effects of fluoride exposure on vectorial bicarbonate transport, cell viability, and the development of transepithelial resistance. To obtain...

In the previous paper (I), we demonstrated that when human bone powder was allowed to come into physicochemical equilibrium with bicarbonate-free buffers, it reproduced a constant ion product [Ca++13 [PO?12 over the pH range from 6.6 to 7.6. The free calcium and trivalent phosphate concentrations varied with pH and were reciprocally related to one another, but the concentration of total inorgan...

Gall bladder bile is more acid that hepatic bile and this has been attributed to bicarbonate absorption by the gall bladder epithelium. The aim of this study was to investigate in vitro the acid base changes that occur across the human gall bladder mucosa. Fresh gall bladder tissue was obtained at cholecystectomy and placed in an Ussing Chamber and perfused with Ringer-Krebs glucose bicarbonate...

Bicarbonate ion, not dissolved CO(2) gas, is shown to increase 4- to 5-fold the rate of dichlorophenol indophenol reduction by isolated maize (Zea mays) chloroplasts. Glutaraldehyde fixed chloroplasts continue to exhibit bicarbonate-dependent 2,6-dichlorophenol indophenol reduction. Bicarbonate is shown to act close to the oxygen-evolving site, i.e. prior to the electron donation site of diphen...

Using ion-exchange resins, a multiple-unit type of oral floating dosage system has been prepared to prolong gastric emptying time of dosage form. The system is composed of beads of drug-resin complex, which are loaded with bicarbonate ions and coated with a hydrophobic polymer. The system is so designed that when the beads reach the stomach, chloride ions are exchanged with bicarbonate and drug...

The growth and development of competence by group H streptococci, strain Challis, were compared in synthetic, semisynthetic, and complex media with respect to the cultural conditions required, time of onset and persistence of competence and transformation efficiency. Provided that cultural conditions were strictly controlled in the synthetic system, transformation frequencies of 1% or above wer...

echocardiography. All attending phy-sicians/cardiologists were blinded to the BNP results. To determine the diagnostic accuracy of the two assays for CHF, we performed ROC plot analysis, and areas under the curve (AUC) were calculated for both BNP assays. Comparisons between AUC were assessed according to the method of Hanley and McNeil (10). Cutoff values for the two methods were determined at...

To the Editor: In his review on acid–base disorders, Seifter (Nov. 6 issue)1 attempts to integrate the “traditional, bicarbonate-centered model” described by Davenport2 and Boron3 with Stewart’s strong-ion-difference model4: strong ion difference (in mmol per liter) = [Na+] + [K+] + [Ca2+] + [Mg2+] – [Cl−]. In unbuffered salt solutions, strong ion difference = [OH−] – [H+] and is thus a pH surr...