Biomedical subjects
Publications and source records attributed to J E Abraham.
Crossbites are a prevalent condition in children. They represent a challenge to the clinician in both diagnosis and treatment planning. Crossbites may be dental or skeletal in etiology. A thorough clinical assessment and accurate records are necessary. Treatment modalities will vary according to the specific diagnosis.
The influence of enflurane, a volatile general anesthetic, on [3H]MK-801 binding to a site in the ion channel of the N-methyl-D-aspartate (NMDA) receptor was determined in membranes from rat cerebral cortex. Enflurane disrupted glutamate stimulation of [3H]MK-801 (1 nM) binding with an IC50 of 0.4 mM. This inhibition was associated with a decrease in receptor affinity with no change in the number of [3H]MK-801 binding sites. Basal [3H]MK-801 binding measured in the absence of glutamate was not affected by enflurane. In contrast, [3H]CGS-19775 binding to the glutamate recognition site on the NMDA receptor was only weakly inhibited by enflurane (e.g., less than 20% inhibition of 5 nM [3H]CGS binding by 1.2 mM enflurane). Glycine, a positive allosteric NMDA receptor modulator, markedly attenuated the inhibition of glutamate-stimulated [3H]MK-801 binding by enflurane, with an EC50 of approximately 0.8 microM. Thus, enflurane selectively inhibits glutamate activation of the NMDA receptors, and an allosteric modulator attenuates this action. These effects could reflect anesthetic action at the glycine binding site or at another, undefined site which influences activation of the ion channel. These findings raise the possibility that inhibition of transmission at NMDA receptors contributes to the development of the anesthetic state.
Mercury levels in blood and in mouth air before and after chewing were measured in 47 persons with and 14 persons without dental amalgam restorations. Questionnaires relating to exogenous sources of mercury exposure were administered to both groups. Differences in the mouth air mercury levels before and after chewing were statistically significant in the group with amalgams, but not in the group without amalgams. Analysis of the data from the questionnaires indicated that little or no exogenous exposure to mercury occurred among the two groups. Blood mercury concentrations were positively correlated with the number and surface area of amalgam restorations and were significantly lower in the group without dental amalgams.
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