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Biomedical subjects

D J Page

Publications and source records attributed to D J Page.

5 recordsLinked to original sources
PubMed1991

A study of the effect of fluoride delivered from solution and dentifrices on enamel demineralization.

An in vitro demineralization model has been developed and used to examine the effect of various fluoride treatments on early enamel demineralization. The effect of fluoride treatments on the calcium demineralization rate of enamel was studied by analyzing the amount of calcium which demineralized from teeth into solution when the teeth were exposed to weak acid solutions. Continuous (72 h total) exposure of enamel to very low levels of fluoride, 0.014 ppm, was observed to have a protective effect against demineralization, as was intermittent exposure to higher levels of fluoride delivered from solution and from dentifrices for shorter periods of time (40 min total). This work suggests that the residual salivary fluoride concentrations reported to be reached by water fluoridation (0.016 ppm) or brushing with a fluoride-containing dentifrice (0.014 ppm) give a level of fluoride in saliva which may give some protection to the dental enamel from demineralization.

Adult↗
PubMed1990

Evidence for fast and discriminatory electron transfer of proteins at modified gold electrodes.

The electrochemistry of the redox proteins, cytochrome c, cytochrome b5, plastocyanin and ferredoxin at modified gold electrodes has been examined on the basis that electron transfer takes place at electroactive sites which are microscopic in size. Using this model, it is now proposed that electrochemistry of these proteins occurs at suitably modified sites with fast rates at potentials near the standard redox potential. The microscopic model implies that redox proteins and enzymes take part in fast electron transfer at specific sites on the electrode, other sites being completely ineffective. This form of molecular recognition, i.e. the ability to discriminate between the different sites on an electrode surface, mimics homogeneous redox reactions wherein redox active proteins 'recognize' their biological partners in a very specific sense. Previously, protein electrochemistry has been interpreted via use of a macroscopic model in which the proteins are transported to the electrode surface by linear diffusion followed by quasi-reversible or irreversible electron transfer to the electrode surface. The microscopic model, which assumes that the movement of the protein occurs predominantly by radial diffusion to very small sites, would appear to explain the data more satisfactorily and be consistent with biologically important, homogeneous redox reactions which are known to be fast.

Cytochrome c Group↗