Search

The acute effects of smokeless tobacco (ST) on buccal mucosal transport and barrier function were studied by means of in vivo and in vitro techniques. In humans, in vivo exposure to 0.5 g ST transiently increased the transmural electrical potential difference (PD). However, despite continued exposure, PD returned to baseline within 20 min. The mechanisms for these changes were explored by use of dog buccal mucosa mounted in Ussing chambers. Luminal exposure to a Ringer-extract of ST (EOST) increased PD and short-circuit current (Isc) and decreased electrical resistance (R), with changes reversible upon removal of EOST from the bath. Further, radioisotopic fluxes showed that the increase in Isc in EOST-exposed tissues was accompanied by increased absorption of electrolytes (Na, Cl, and other ions), and the decrease in R was accompanied by increased permeability to mannitol. Light microscopy of tissues exposed to EOST showed no morphological changes after exposure to 0.5 g of ST, but after exposure to 1.5-2.5 g of ST, dilated intercellular spaces were identified. Contact of aqueous media with ST led to the release of electrolytes and other soluble compounds into solution. To determine the effect of electrolyte release on buccal function, we exposed mucosaeluminally to a solution with ion composition and/or osmolality similar to EOST or to one with an EOST previously dialyzed against Ringer. Solutions with similar ion composition and/or osmolarity changed PD, Isc, and R in a manner similar to EOST, while dialyzed-EOST had no effect. In addition, luminal nicotine produced effects different from EOST, decreasing PD and Isc and increasing R. These results indicate that ST can acutely alter buccal transport and barrier function by creating, through electrolyte release, electrochemical and osmolar gradients across the tissue. [ABSTRACT FROM AUTHOR]

Calix[4]arenes, calix[4]resorcarenes, and anionic cyclodextrin derivatives were examined as chiral NMR solvating agents. The calix[4]arenes were prepared by attachment of amino acids through the hydroxyl groups of the phenol rings. Chloroform-, methanol-, and water-soluble derivatives were prepared and tested with a range of substrates. Chloroform-soluble chiral calix[4]resorcarenes were prepared by attachment of chiral primary and secondary amines and examined in NMR applications with a variety of substrates. Sulfated and carboxymethylated beta-cyclodextrin are effective at causing enantiomeric discrimination in the (1)H NMR spectra of organic cations. Lanthanide ions associate at the carboxymethyl groups and cause sizeable shifts and enhancements in enantiomeric discrimination in the spectra of organic cations. The enhancements caused by the lanthanide ion are large enough that much lower concentrations of the cyclodextrin can be used as compared to conventional analyses., (Copyright 2003 Wiley-Liss, Inc.)

The efficacy of sucralfate suspension in the treatment of reflux esophagitis was assessed in a multicenter, randomized, double-blind, placebo-controlled trial. Sixty-eight patients with symptomatic and endoscopic esophagitis received either sucralfate suspension (n = 31) or liquid placebo (n = 37) for eight weeks. The two groups were comparable at entry with the exception that despite randomization, a disproportionately high number of patients with esophageal ulcers were assigned to receive sucralfate. After four and eight weeks of treatment, both groups had reduced heartburn frequency and severity, but there was no difference in improvement between sucralfate and placebo (p greater than 0.05). Endoscopic results after eight weeks of sucralfate treatment revealed complete healing in 36 percent (placebo, 35 percent) and improvement in an additional 45 percent (placebo, 24 percent). Although neither of these differences was significant, the percent of patients in whom healing or improvement occurred with sucralfate (81 percent) was greater than with placebo (59 percent) (p = 0.07). These data fail to establish that eight weeks of treatment with sucralfate suspension improves symptoms or heals lesions in reflux esophagitis at a rate significantly greater than placebo. However, the unequal distribution of patients with ulcers and the trend toward endoscopic improvement indicate that a potential beneficial effect of sucralfate suspension for the treatment of reflux esophagitis cannot be excluded.