Effect of polymers used in saliva substitutes on demineralized bovine enamel and dentin.

PURPOSE: To evaluate the effects of porcine mucin- and carboxymethylcellulose-based (CMC) solutions on the inhibition of demineralization of pre-demineralized bovine enamel and dentin in vitro. Additionally the sugar substitutes sorbit or xylit were added to the various solutions. METHODS: 54 enamel and dentin samples were prepared from 14 freshly extracted permanent bovine central incisors. The samples were demineralized (pH 5.0 for enamel and pH 5.5 for dentin; 14 days) and subsequently exposed to either mucin- or CMC-based solutions combined with xylit and sorbit at pH 5.5. After in vitro exposure, the specimens were cut perpendicular to the enamel/dentin surface and the sections were ground (4000 grit) to a uniform thickness (100 microm). Mineral loss and lesion depths were evaluated from microradiographs with a dedicated software package (TMR 2.0.27.2). RESULTS: For both dental hard tissues, storage in the mucin-containing solutions resulted in significantly higher lesion depths (deltaLD), but lower mineral loss values (deltadeltaZ) compared to the CMC-containing solutions (P< 0.05; 2-way ANOVA). For the dentin specimens, significant differences in deltadeltaZ were observed between sorbit and xylit (P< 0.05; 2-way ANOVA). The mineral loss and lesion depths of the enamel specimens did not differ significantly after storage in the various solutions (P> 0.05; Bonferroni post hoc test). For the dentin specimens stored in the solution containing mucin/xylit the mineral loss was significantly decreased compared to the other mucin groups as well as to the CMC/xylit solution (P< 0.05; Bonferroni post hoc test).

Identification, synthesis and pharmacological activity of moxonidine metabolites.

The metabolism of moxonidine, 4-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-6-methoxy-2-methyl-5-pyrimidinamine, LY326869, in rats, mice, dogs, and humans has been examined. At least 17 metabolites were identified or tentatively identified in the different species by HPLC, LC/MS and LC/MS/MS. The identities of seven of the major metabolites have been verified by independent synthesis. The metabolites are generally derived from oxidation and conjugation pathways. Oxidation occurred at the imidazolidine ring as well as the methyl at the 2 position of the pyrimidine ring. All seven metabolites were examined in the spontaneously hypertensive rats (3 mg kg(-1), i.v.) for pressure and heart rate. Only one, 2-hydroxymethyl-4-chloro-5-(imidazolidin-2-ylidenimino)-6-methoxypyrimidine, exerted a short-lasting decrease in blood pressure, albeit attenuated in magnitude compared to moxonidine.